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Title:
RECIPROCATING COMPRESSOR
Document Type and Number:
WIPO Patent Application WO/2019/058221
Kind Code:
A1
Abstract:
A reciprocating compressor (1 ) comprises a cylinder (2), a piston (3), an intake duct (4), defining an intake space (4A), a discharge duct (6) defining a discharge space (6A), an intake valve (8) disposed in the intake duct (4), a discharge valve (9) disposed in the discharge duct (6); for each discharge valve (9) and intake valve (8), the reciprocating compressor comprises a blocking unit (100) configured to block the respective intake valve (8) or discharge valve (9) at its operating position; for each intake valve (8) and discharge valve (9), the reciprocating compressor comprises a dead space including a corresponding under valve space (1 1 ); each blocking unit (100) includes an abutment surface (100A), designed to butt against the respective intake valve (8) or discharge valve (9) in an insertion direction (I), a blocking member (100B), removably inserted in the respective intake duct (4) or discharge duct (6), abutting against the respective intake valve (8) or discharge valve (9) to prevent it from moving in an extraction direction (E).

Inventors:
GARDELLI, Paolo (Via Omero 3, Parma, 40123, IT)
CASTAGNETTI, Max (Strada Barilla 17, Montecchio Emilia, 42027, IT)
BARBANTI, Giovanni (Via Podgora 1, Casalecchio Di Reno, 40033, IT)
FARETRA, Marco (Via Conte Guido Rangoni 26, Longiano, 47020, IT)
Application Number:
IB2018/056996
Publication Date:
March 28, 2019
Filing Date:
September 13, 2018
Export Citation:
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Assignee:
FORNOVO GAS S.R.L. (Via Ponticelli 5-7, Traversetolo, 43029, IT)
International Classes:
F04B49/16; F04B39/10; F04B39/12; F04B39/14
Foreign References:
DE301556C
US2075099A1937-03-30
GB257848A1926-09-09
US3354790A1967-11-28
Attorney, Agent or Firm:
CONTI, Marco (Via di Corticella 87, Bologna, 40128, IT)
Download PDF:
Claims:
CLAIMS

1 . A reciprocating compressor (1 ), comprising:

- a cylinder (2) defining an internal space (2A);

- a piston (3) slidable inside the internal space (2A) of the cylinder (2);

- an intake duct (4), defining an intake space (4A) and having a first end and a second end which is open to the internal space (2A) of the cylinder

(2) to define an intake port (5);

- a discharge duct (6), defining a discharge space (6A) and having a first end and a second end which is open to the internal space (2A) of the cylinder (2) to define a discharge port (7);

- an intake valve (8) disposed in the intake duct (4) and spaced from the intake port (5);

- a discharge valve (9) disposed in the discharge duct (6) and spaced from the discharge port (7);

- for each discharge valve (9) and intake valve (8), a blocking unit (100) configured to block the respective intake valve (8) or discharge valve (9) at its operating position;

- a dead space, including for each intake valve (8) and discharge valve (9), a corresponding under valve space (1 1 ), formed by a stretch of the intake space (4A) or discharge space (6A), delimited by the intake valve (8) or discharge valve (9) and by the intake port (5) or discharge port (7), respectively,

characterized in that each blocking unit (100) includes:

- an abutment surface (100A), designed to butt against the respective intake valve (8) or discharge valve (9) in an insertion direction (I), oriented from the first to the second end of the respective intake duct (4) or discharge duct (6);

- a blocking member (100B), removably inserted in the respective intake duct (4) or discharge duct (6), abutting against the respective intake valve (8) or discharge valve (9) to prevent it from moving in an extraction direction (E) oriented from the second to the first end of the respective intake duct (4) or discharge duct (6).

2. The compressor (1 ) according to claim 1 , wherein each intake duct (4) and discharge duct (6) comprises a first stretch (601 ) and a second stretch (602), the first stretch (601 ) having a flow cross section which is greater than the flow cross section of the second stretch (602), to define a shoulder.

3. The compressor (1 ) according to claim 2, wherein each blocking unit (100) includes an abutment bush (100A'), removably interposed between the shoulder and the respective intake valve (8) or discharge valve (9), to define the abutment surface (100A).

4. The compressor (1 ) according to claim 3, wherein the abutment bush (100A') of the blocking unit (100) of the intake valve (8) has a first axial extension (hi ), and the abutment bush (100A') of the blocking unit (100) of the discharge valve (9) has a second axial extension (h2), different from the first axial extension (hi ).

5. The compressor (1 ) according to any one of the preceding claims, comprising, for each intake valve (8) and discharge valve (9), an adjustment bush (12), removably interposed between the respective intake valve (8) or discharge valve (9) and the blocking member (100B).

6. The compressor (1 ) according to any one of the preceding claims, wherein, each intake valve (8) and discharge valve (9) comprises:

- an underside surface (10A), in contact with the abutment surface (100A) of the respective blocking unit (100);

- a top surface (10B), opposite to the underside surface and in contact with the blocking member (100B) of the respective blocking unit (100).

7. The compressor (1 ) according to any one of the preceding claims, wherein each intake duct (4) and discharge duct (6) has a smooth inside surface and wherein each intake valve (8) and discharge valve (9) has a lateral surface (10C) which is geometrically shaped to slide freely along the respective intake duct (4) or discharge duct (6).

8. The compressor (1 ) according to any one of the preceding claims, wherein, for each blocking unit (100), the blocking member (100B) comprises:

- a first end (100B'), removably connected to the first end (60A) of the respective intake duct (4) or discharge duct (6);

- a second end (100B"), abutting against the respective intake valve (8) or discharge valve (9).

9. The compressor (1 ) according to claim 8, wherein the blocking member (100B) has an extension along a longitudinal axis (X) and includes, at its first end (100B'), a connecting flange (102B), which extends radially relative to the longitudinal axis (X).

10. The compressor (1 ) according to claim 9, wherein the connecting flange (102B) is removably fixed to the respective intake duct (4) or discharge duct (6), externally of an inside surface of the intake duct (4) or discharge duct (6) itself.

1 1 . The compressor (1 ) according to any one of the preceding claims, comprising:

- a crosshead (13)

- an additional intake duct (4'), defining an additional intake space (4Α') and having a first end and a second end which is open to the internal space (2A) of the cylinder (2) to define an additional intake port (5');

- an additional discharge duct (6'), defining an additional discharge space (6Α') and having a first end and a second end which is open to the internal space (2A) of the cylinder (2) to define an additional discharge port (7'); - an additional intake valve (8') disposed in the additional intake duct (4') and spaced from the additional intake port (5');

- an additional discharge valve (9') disposed in the additional discharge duct (6') and spaced from the additional discharge port (7');

and configured to compress a fluid both by the sliding of the piston (3) in a going direction (A) from the additional intake port (5') to the intake port (5), and by the sliding of the piston (3) in a return direction (R) from the intake port (5) to the additional intake port (5').

12. A method for making a reciprocating compressor (1 ) including at least one valve (10), comprising the following steps:

- providing a cylinder (2) defining an internal space (2A);

- providing a duct (F1 ), defining a sweeping space (60C) and having a first end and a second end which is open to the internal space (2A) of the cylinder (2) to define an access port (70);

- providing a valve (10) disposed in the duct (60) and spaced from the access port (70);

- determining dead space including an under valve space (1 1 ), formed by a stretch of the sweeping space (60C), the stretch being delimited by the valve (10) and the access port (70);

- deriving a valve (10) distance as a function of the under valve space (1 1 ), being the distance by which the valve (10) is spaced from the access port (70) along a longitudinal axis (X) of maximum extension of the duct (60);

- defining (F2) an abutment surface (100A), which is perpendicular to the longitudinal axis (X) of the duct (60), at the valve (10) distance from the access port (70) and against which the valve (10) comes into abutment in an insertion direction (I) oriented from the first end (60A) to the second end (60B) of the duct (60);

- inserting (F3) the valve (10) into the duct (60) until it comes into abutment with the abutment surface (100A);

- blocking (F4) the valve (10) by means of a blocking member (100B) which abuts against the valve (10) to prevent it from moving in an extraction direction (E) oriented from the second end (60B) to the first end (60A) of the duct (60).

13. The method according to claim 12, comprising a step of reaming the duct (60) and creating a first stretch (601 ) of the duct (60) and a second stretch (602) of the duct (60), the first duct stretch (601 ) having a flow cross section which is larger than the flow cross section of the second duct stretch (602), to define a shoulder.

14. The method according to claim 13, wherein the step of defining (F2) the abutment surface (100A) comprises inserting (F2') an abutment bush (100A') into the duct (60) until its first circular crown comes into abutment with the shoulder and wherein a second circular crown of the abutment bush (100A') defines the abutment surface (100A).

15. The method according to any one of claims 12 to 14, wherein the step of blocking (F4) the valve (10) comprises a step of inserting the blocking member (100B) into the duct (60) until its second end comes into contact with the valve (10).

16. The method according to any one of claims 12 to 15, wherein the step of blocking (F4) the valve (10) comprises a step of connecting (F4') the first end of the blocking member (100B) to the duct (60).

17. The method according to any one of claims 12 to 16, comprising the following steps:

- providing one or more additional ducts (60) forming a plurality of ducts, each defining a respective sweeping space (60C) and having a first end and a second end which is open to the internal space (2A) of the cylinder (2) to define a respective access port (70);

- providing one or more additional valves (10) forming a plurality of valves, each disposed in the respective duct (60) and spaced from the respective access port (70);

- calculating the dead space including, for each valve (10), the respective under valve space (1 1 ), formed by a stretch of the sweeping space (60C), of the respective duct (60), which is delimited by the respective valve (10) and by the respective access port (70);

- deriving the valve distance, as a function of the respective under valve space (1 1 ), being the distance of each valve (10) from the access port (70) of the respective duct (60) along the longitudinal axis (X);

- defining the respective abutment surface (100A) of the valve (10) at the respective valve distance from the respective access port (70); - inserting each valve (10) into the respective duct (60) until it comes into abutment against the respective abutment surface (100A);

- blocking each valve (10) by means of the respective blocking member (100B).

Description:
DESCRIPTION

RECIPROCATING COMPRESSOR

Technical field

This invention relates to a reciprocating compressor. This disclosure is applicable in the energy industry, in particular in the field of industry which addresses the design and production of fluid machinery. Specifically, a reciprocating compressor is a machine which transfers energy to a fluid which uses that energy for any of several different purposes: for example, but not limited to, conveying the fluid from the site where it is extracted to a site where it is processed or used.

Background art

Typically, a reciprocating compressor is a machine with at least one component that moves with reciprocating motion relative to the other components. In particular, a reciprocating compressor is characterized by a piston that moves with reciprocating motion inside a cylinder.

When sizing a reciprocating compressor, several different parameters are taken into account. In particular, the parameter which most influences the design of a reciprocating compressor is the flow range, which is substantially correlated with cylinder size, piston stroke, compressor motor rotation speed and compressor thermodynamic efficiency.

The variability of the operating parameters, and of flow in particular, has thus led to the sizing of a different type of reciprocating compressor for every specific application required. This has considerably reduced the possibility of standardizing reciprocating compressor sizes, with the result that manufacturers of reciprocating compressors are faced with greater economic and logistic burdens.

The need to standardize reciprocating compressor size while maintaining a wide flow range is usually obtained by modifying some of the compression parameters: dead space, for example. Generally speaking, a reciprocating compressor is produced whose maximum flow is reduced by increasing the percentage of dead space in the reciprocating compressor. Dead space refers to the volume of gas which, after compression, remains trapped in the cylinder or under the intake and discharge valves.

Reducing the flow by increasing the dead space, however, leads to reduced efficiency of the reciprocating compressor. Reduced efficiency translates as higher operating costs of the compressor.

In some prior art solutions, the cylinder head is movable along the axis of the cylinder in such a way as to modify the distance between the piston and the cylinder head. In a solution of this type, however, the problem remains of not providing effective control of the dead space specified in the design. This translates as a reduction in efficiency which might not justify the reduction in the production cost.

Other solutions, on the other hand, involve modifying the part of the dead space which remains under the intake and discharge valves in the respective intake and discharge ducts. In the rest of this description, this part of the dead space is referred to as "under valve space".

In particular, documents US5141413A, DE301556C and US5564906A disclose three solutions which allow modifying the dead space of the compressor by modifying the under valve space.

Document US5141413A describes a solution in which a reciprocating compressor has an intake valve whose position is adjustable along the axis of the cylinder. In particular, the valve is threadedly engaged with a rod. Thus, by turning the rod, the position of the intake valve can be adjusted along the cylinder axis. The result is that the valve can be progressively moved towards or away from the compressor piston, thereby allowing the volume compressed by the piston to be reduced. Document US5564906A describes a solution for adapting the position of the intake valve along the axis of the cylinder by coupling the valve to a threaded rod, as in document US5141413A. In this case, however, the threaded rod is operated through apertures made in the compressor, which allow moving a bolt attached to the threaded rod.

However, neither US5564906A nor US5141413A solve the problem of having a wide flow range because they are more suitable for minor adjustments which can be carried out even when the compressor is in service. Also, they are not solutions which allow adjustments to be made during the construction of the compressor. Moreover, they do not allow the dead space to be distributed optimally between the plurality of compressor valves, that is to say, in such a way as to minimize the reduction in the efficiency of the reciprocating compressor. In short, the above solutions do not allow producing a compressor whose size can be very easily adapted and adjusted to work on a wide flow range without overly reducing compression efficiency.

Disclosure of the invention

The aim of this disclosure is to provide a reciprocating compressor to overcome the above mentioned disadvantages of the prior art.

More specifically, the aim of this disclosure is to provide a reciprocating compressor which can be adjusted at the assembly stage for a wide flow range in a particularly easy and cost effective manner.

A further aim of this invention is to propose a reciprocating compressor whose thermodynamic efficiency is the highest obtainable for a given dead space.

This aim is fully achieved by the reciprocating compressor of this disclosure as characterized in the appended claims.

In an embodiment, the reciprocating compressor comprises a cylinder defining an internal space therein. In an embodiment, the reciprocating compressor comprises a piston. In an embodiment, the piston is slidable within the internal space in the cylinder.

In an embodiment, the reciprocating compressor comprises an intake duct defining an intake space. In an embodiment, the intake duct comprises a first end and a second end. In an embodiment, the second end opens into the internal space in the cylinder to define an intake port.

In an embodiment, the reciprocating compressor comprises a discharge duct defining a discharge space. In an embodiment, the discharge duct comprises a first end and a second end. In an embodiment, the second end opens into the internal space in the cylinder to define a discharge port. In an embodiment, the reciprocating compressor comprises an intake valve. In an embodiment, the intake valve is located in the intake duct. In an embodiment, the intake valve is spaced from the intake port.

In an embodiment, the reciprocating compressor comprises a discharge valve. In an embodiment, the intake valve is located in the discharge duct. In an embodiment, the discharge valve is spaced from the discharge port. In an embodiment, the reciprocating compressor comprises a blocking unit for each intake or discharge valve. In an embodiment, each blocking unit is configured to block the respective intake or discharge valve at its operating position. By "operating position" is meant the position of a discharge or intake valve upon completion of compressor assembly operations. This operating position is defined at the design stage and is modified during the working life of the compressor only within a very small tolerance range.

In an embodiment, the compressor comprises a dead space. By "dead space" is meant the part of the fluid which, after compression, remains trapped in the cylinder and subsequently expands. On account of lost compression work, this dead space causes a reduction in the thermodynamic efficiency of, hence also a reduction in the flow effectively processed by, the reciprocating compressor.

Precisely for this reason, the dead space is sometimes used as an adjustment method for reciprocating compressors.

In an embodiment, the dead space includes, for each intake and discharge valve, a corresponding under valve space. In an embodiment, the under valve spacer is made up of a stretch of the intake or discharge space. In an embodiment, the stretch of intake or discharge space is delimited by the intake or discharge valve and the intake or discharge port.

In particular, in an embodiment, each blocking unit comprises an abutment surface. By "abutment surface" is meant a surface designed to come into contact with an element which moves along a direction perpendicular to the abutment surface to prevent the element from moving beyond the abutment surface.

In an embodiment, the abutment surface is designed to butt against the respective intake or discharge valve in an insertion direction. In an embodiment, the insertion direction is oriented from the first to the second end of the respective intake or discharge duct.

In an embodiment, the blocking unit comprises a blocking member. In an embodiment, the blocking member is removably inserted in the respective intake or discharge duct. In an embodiment, the blocking member abuts against the respective intake or discharge valve to prevent it from moving in an extraction direction. In an embodiment, the extraction direction is oriented from the second to the first end of the respective intake or discharge duct.

The term "abuts" is used to mean the action by which the blocking member applies pressure on the valve to prevent the valve from moving in a direction opposite to that of the pressure applied by the blocking member.

This configuration allows varying the position of the intake and discharge valves along the duct by varying the position of abutment surface and the features of the blocking member. Varying the position in this way causes the respective under valve space of each intake or discharge valve to be varied accordingly. Lastly, varying the under valve space allows achieving the aim of this disclosure, that is to say, adapting the reciprocating compressor to a wide flow range at an assembly stage, while keeping the size and design of the compressor unchanged.

In an embodiment, each intake and discharge duct comprises a first stretch and a second stretch. In an embodiment, the first stretch has a flow cross section which is greater than the flow cross section of the second stretch. In an embodiment, the difference between the flow cross section of the first stretch and that of the second stretch defines a shoulder. By "flow cross section of a duct" we mean the surface perpendicular to an axis of maximum extension of the duct and delimited by an inside perimeter of an inside surface of the duct itself. The term "shoulder" on the other hand, is used to mean a surface perpendicular to the axis of maximum extension of a duct and delimited by the inside perimeter of an inside surface of a first stretch of a duct and by the inside perimeter of an inside surface of a second stretch of a duct.

In an embodiment, each blocking unit comprises an abutment bush. In an embodiment, the abutment bush is removably interposed between the shoulder and the respective intake or discharge valve to define the abutment surface. In other words, the abutment bush comprises two circular crowns. A first circular crown is in contact with the respective shoulder of the intake or discharge duct. A second circular crown is in contact with the respective intake or discharge valve. In an embodiment, each intake or discharge valve abuts against the respective abutment bush.

In one embodiment, the shoulder defines the abutment surface.

In an embodiment, the abutment bush of the blocking unit of the intake valve has a first axial extension. In an embodiment, the abutment bush of the blocking unit of the discharge valve has a second axial extension. In an embodiment, the second axial extension is different from the first axial extension.

In an embodiment, the compressor comprises an adjustment bush for each intake and discharge valve. In an embodiment, each adjustment bush is removably interposed between the respective intake or discharge valve and the blocking member. In an embodiment, each adjustment bush is removably interposed between the respective intake or discharge valve and the abutment bush. In an embodiment, the adjustment bush, at the operating position, defines the abutment surface and acts as an extension of the abutment bush. In an embodiment, the adjustment bush abuts against the abutment bush which in turn abuts against the respective shoulder of the intake or discharge duct. In an embodiment, the adjustment bush abuts directly against the respective shoulder of the intake or discharge duct. In this embodiment, the adjustment bush coincides with the abutment bush.

In an embodiment, the intake and discharge valves each have an underside surface. By "underside surface" is meant the sum of all the surfaces perpendicular to the axis of maximum extension of the cylinder and on the same side of the valve. In an embodiment, the underside surface is in contact with the abutment surface of the respective blocking unit. In an embodiment, the underside surface of each of the intake and discharge valves is in contact with the abutment bush. In an embodiment, the underside surface of each of the intake and discharge valves is in contact with the adjustment bush. In an embodiment, the underside surface of each of the intake and discharge valves is in contact with the shoulder of the respective intake or discharge duct.

In an embodiment, the intake and discharge valves each have a top surface, opposite to the underside surface. By "top surface" is meant the sum of all the surfaces perpendicular to the axis of maximum extension of the cylinder and on the side opposite to the underside surface. In an embodiment, each top surface is in contact with the blocking member of the respective blocking unit. In an embodiment, each top surface is in contact with the adjustment bush of the respective blocking unit.

In an embodiment, the intake and discharge valves each have a lateral surface which connects the underside surface to the top surface.

In an embodiment, the intake and discharge ducts each have a smooth inside surface.

In an embodiment, the intake and discharge ducts each comprises a first end, further from the respective intake or discharge port, and a second end, closer to the respective intake or discharge port. In an embodiment, the intake and discharge ducts each comprises a plurality of fastening holes, disposed on the first end of the respective discharge or intake duct and configured to be coupled to connecting elements such as, for example but not limited to, bolts, nails, through screws, tap screws or rivets. In an embodiment, the intake and discharge ducts each have a fastening thread on its outside surface. In an embodiment, the intake and discharge ducts each have a third stretch with a flow cross section which is smaller than the first and second stretches in which the fastening thread is formed. In an embodiment, the fastening thread is on the inside surface of each of the intake and discharge ducts.

In an embodiment, the lateral surface of the intake and discharge valves are each geometrically shaped to allow the respective intake or discharge valve to slide freely along the respective intake or discharge duct. By "geometrically shaped to slide" we mean the absence of any profile on the lateral surface preventing the intake or discharge valve from being inserted into the respective duct before placing the blocking member. In other words, on the one hand the maximum diameter of each intake or discharge valve must be smaller than the minimum diameter of the first stretch of the respective duct, to allow the valve to be inserted, and on the other, the maximum diameter of each intake or discharge valve must be greater than the minimum diameter of the second stretch of the respective duct, to allow the valve to stop being inserted.

In an embodiment, the blocking member of each blocking unit comprises a first end. In an embodiment, the first end is removably connected to the first end of the respective intake or discharge duct. In an embodiment, the first end is connected to the first end of the respective intake or discharge duct by a connecting thread. In an embodiment, the first end is connected to the first end of the respective intake or discharge duct by connecting elements such as, for example but not limited to, bolts, nails, through screws, tap screws or rivets. In an embodiment, the first end is connected to the inside surface of the respective first end of the intake or discharge duct.

In an embodiment, the first end is connected to the outside surface of the respective first end of the intake or discharge duct.

In an embodiment, the blocking member of each blocking unit comprises a second end. In an embodiment, the second end abuts against the respective intake or discharge valve. In an embodiment, the second end abuts against the adjustment bush of the respective intake or discharge valve.

In an embodiment, each blocking member has an extension along a longitudinal axis. In an embodiment, the blocking member includes a connecting flange at its first end. In an embodiment, the connecting flange extends radially relative to the longitudinal axis of the blocking member. In an embodiment, the connecting flange comprises a plurality of fastening holes configured to be coupled to connecting elements such as, for example but not limited to, bolts, nails, through screws, tap screws or rivets. In an embodiment, the connecting flange comprises the connecting thread. In an embodiment, the connecting thread is on the inside surface of the blocking member. In an embodiment, the connecting thread is on the outside surface of the blocking member.

In an embodiment, the connecting flange is removably fastened to the respective intake or discharge duct. In an embodiment, the connecting flange is removably fastened to the respective intake or discharge duct externally of the inside surface of the intake or discharge duct.

In an embodiment, the connecting flange is removably fastened to the respective intake or discharge duct on the inside surface of the intake or discharge duct. In an embodiment, the connecting flange is removably fastened to the first end of the respective intake or discharge duct. In an embodiment, the first end of each intake or discharge duct comprises a fastening flange. In an embodiment, the fastening flange comprises a plurality of fastening holes configured to be coupled to connecting elements such as, for example but not limited to, bolts, nails, through screws, tap screws or rivets. In an embodiment, the first end of the duct comprises the plurality of fastening holes configured to be coupled to the connecting elements. In an embodiment, the first end of each intake or discharge duct comprises a fastening thread. In an embodiment, the fastening thread is located on the inside surface of the respective intake or discharge duct. In an embodiment, the fastening thread is located on the outside surface of the respective intake or discharge duct.

In an embodiment, the compressor comprises a crosshead. In an embodiment, the compressor comprises an additional intake duct, defining an additional intake space and having a first end and a second end which is open to the internal space of the cylinder to define an additional intake port.

In an embodiment, the compressor comprises an additional discharge duct, defining an additional discharge space and having a first end and a second end which is open to the internal space of the cylinder to define an additional discharge port.

In an embodiment, the compressor comprises an additional intake valve disposed in the additional intake duct and spaced from the additional intake port.

In an embodiment, the compressor comprises an additional discharge valve disposed in the additional discharge duct and spaced from the additional discharge port.

In an embodiment, the compressor is configured to compress a fluid both by the sliding of the piston in a going direction oriented from the additional intake port to the intake port, and by the sliding of the piston in a return direction oriented from the intake port to the additional intake port. In this embodiment, for the same piston diameter and stroke, the flow processable by the compressor increases. This technology is commonly known as double-acting compressor. In an embodiment, therefore, the compressor is a double-acting compressor.

This disclosure also provides a method for assembling a valve in a reciprocating compressor.

In one embodiment, the method comprises a step of providing a cylinder defining an internal space.

Below is a description of a reciprocating compressor. The compressor has an intake duct and a discharge duct having one or more of the features described above.

In the following description of the method, reference is generically made to a duct in which a valve is positioned, meaning that:

i) that duct is the intake duct and the valve is the intake valve; or

ii) that duct is the discharge duct and the valve is the discharge valve. Furthermore, the method according to the disclosure can be applied both to the intake valve and to the discharge valve.

In the following description of the method, reference is generically made to a sweeping space which can be accessed through an access port, meaning that:

i) the sweeping space is the intake space and the access port is the intake port; or

ii) the sweeping space is the discharge space and the access port is the discharge port.

In an embodiment, the method comprises a step of providing a duct defining a sweeping space and having a first end and a second end which is open to the internal space of the cylinder to define an access port.

In an embodiment, the method comprises a step of providing a valve disposed in the duct and spaced from the access port.

In an embodiment, the method comprises a step of calculating a dead space. The calculation of the dead space takes into account the technical specifications which the buyer of a compressor requires of the manufacturer of the compressor. The dead space is sized mainly as a function of the flow specified by the buyer. In an embodiment, calculating the dead space comprises a step of calculating the under valve space formed by a stretch of the sweeping space, which is delimited by the respective valve and access port.

The under valve space depends on a trend of a flow cross section along a longitudinal axis of the duct and on the distance of the valve from the access port.

In an embodiment, the method comprises a step of deriving a valve distance as a function of the under valve space, the valve distance being the distance by which the valve is spaced from the access port along the longitudinal axis of the valve.

In an embodiment, the method comprises a step of defining an abutment surface. In an embodiment, the method comprises a step of defining an abutment surface perpendicular to the longitudinal axis of the duct. In an embodiment, the abutment surface is defined at the valve distance from the access port.

In an embodiment, the abutment surface butts against the valve in an insertion direction oriented from the first to the second end of the duct. In an embodiment, the method comprises a step of inserting the valve into the duct until it comes into abutment with the abutment surface.

In an embodiment, the method comprises a step of blocking the valve by means of a blocking member which abuts against the valve to prevent it from moving in an extraction direction oriented from the second end to the first end of the duct.

The step of defining the abutment surface and the step of blocking which, in one embodiment, are carried out after the components of the reciprocating compressor have been made, allow adapting the compressor to different flow rates without changing the initial design of the compressor. In effect, changing the position of the abutment surface has a direct effect on the flow processable by the reciprocating compressor. In one embodiment, the method comprises a step of reaming the duct. A duct whose internal diameter is constant is worked by machine tools to create a stretch of duct whose internal diameter is greater than the original internal diameter of the duct.

The term "reaming" is used to denote any machining process by which material is removed from an inside surface of a duct to increase the internal diameter of a specific stretch of the duct.

In an embodiment, the method comprises a step of casting the duct.

In an embodiment, the method comprises a step of creating a first stretch of the duct and a second stretch of the duct.

In an embodiment, this step of generating is the result of reaming the duct obtained from a step of casting. In an embodiment, this step of generating is the result of the step of casting.

In an embodiment, the method comprises a step of generating the first stretch of the duct with a flow cross section which is greater than the flow cross section of the second stretch of the duct.

In an embodiment, this step of generating defines a shoulder.

In an embodiment, the step of defining the abutment surface is a step of inserting an abutment bush into the duct. In an embodiment, the step of defining the abutment surface terminates when a first circular crown of the abutment bush comes into abutment against the shoulder of the duct. In an embodiment, when the first circular crown butts against the shoulder, a second circular crown of the abutment bush defines the abutment surface. In an embodiment, the step of defining the abutment surface coincides with the step of creating the shoulder of the duct. In effect, in such a case, knowing the valve distance during the step of reaming or the step of casting means that the valve distance can be made to coincide with the distance of the shoulder from the access port. In such an embodiment, it is not necessary to place any abutment bush because the shoulder defines the abutment surface.

In an embodiment, the step of blocking the valve comprises a step of inserting the blocking member into the duct. The step of inserting the blocking member ends when a second end of the blocking member comes into abutment against the valve.

In an embodiment, the step of blocking the valve comprises a step of inserting the blocking member into the duct. In an embodiment, the step of blocking the valve comprises a step of connecting the blocking member to the duct at a first end of the blocking member.

In an embodiment, the method comprises a step of providing one or more additional ducts forming a plurality of ducts, each defining a respective sweeping space and having a first end and a second end which is open to the internal space of the cylinder to define a respective access port.

In an embodiment, the method comprises a step of providing one or more additional valves forming a plurality of valves, each disposed in the respective duct and spaced from the respective access port.

In an embodiment, the method comprises a step of calculating the dead space. In this embodiment, the dead space includes, for each valve, the respective under valve space, formed by a stretch of the sweeping space, of the respective duct, which is delimited by the respective valve and the respective access port.

In an embodiment, the method comprises a step of deriving a valve distance as a function of the respective under valve space, the valve distance being the distance by which each valve is spaced from the access port of the respective duct.

In an embodiment, the method comprises a step of defining the respective abutment surface of the valve at the respective valve distance from the respective intake port.

In an embodiment, the method comprises a step of inserting each valve into the respective duct until it comes into abutment with the respective abutment surface.

In an embodiment, the method comprises a step of blocking each valve. In an embodiment, the method comprises a step of blocking each valve using the respective blocking member.

In an embodiment, the valve distance of each valve of the plurality of valves is different from the valve distance of the other valves of the plurality of valves.

This allows the dead space of the compressor to be optimally distributed, thus reducing the negative effects of increasing the dead space, mainly affecting the thermodynamic efficiency.

In an embodiment, the step of calculating the under valve space of each valve, hence the optimum distribution of the dead space, is carried out using a simulation algorithm which simulates the fluid dynamic behaviour of a fluid compressible by the reciprocating compressor. Brief description of the drawings

These and other features will become more apparent from the following detailed description of a preferred, non-limiting embodiment, with reference to the accompanying drawings, in which:

- Figure 1 illustrates a reciprocating compressor in cross section;

- Figure 1 A shows a detail of the compressor of Figure 1 ;

- Figure 2 is a functional diagram of a double acting reciprocating compressor;

- Figures 3, 3A, 4, 4A illustrate embodiments of an intake or discharge valve of the compressor of Figure 1 ;

- Figures 5A, 5B, 5C, 5D, 5E illustrate embodiments of an intake or discharge valve of the compressor of Figure 1 ;

- Figures 6A, 6B, 6C, 6D illustrate the steps of a method for assembling a valve in a reciprocating compressor.

Detailed description of preferred embodiments of the invention

With reference to the accompanying drawings, the numeral 1 denotes a reciprocating compressor. A reciprocating compressor 1 is a motor-driven machine configured to compress a fluid and comprising at least one element which moves with reciprocating motion.

In an embodiment, the compressor 1 comprises a cylinder 2. In an embodiment, the cylinder 2 comprises an internal space 2A delimited by a head, a bottom and a side wall.

In an embodiment, the compressor 1 comprises a piston 3. The piston 3 comprises a plurality of gaskets which prevent gas leaks through the gaps between the cylinder 2 and the piston 3. In an embodiment in which the compressor 1 is a single acting compressor, the piston 3 is connected directly to a connecting rod of a slider-crank mechanism connected to a drive shaft.

In an embodiment in which the compressor 1 is a double acting compressor, the piston 3 is connected to a crosshead 13 in turn connected to the connecting rod of a slider-crank mechanism connected to the drive shaft.

In an embodiment, the compressor 1 comprises an intake duct 4. In an embodiment, the intake duct 4 is made up of a cylinder 2 with variable flow cross section, communicating with an intake chamber 400. In an embodiment, the intake duct 4 communicates with intake fittings without passing by way of the intake chamber 400. In an embodiment, the intake duct 4 comprises an intake space 4A.

The intake duct 4 has an inside surface and an outside surface. The inside surface of the intake duct 4 is the surface that faces the intake space 4A of the intake duct 4. The outside surface is the surface opposite the inside surface. In an embodiment, the second end of the intake duct 4 opens onto the cylinder 2 defining an intake port 5. The intake port 5 is the contact surface between the intake space 4A and the internal space 2A of the cylinder 2.

In an embodiment, the compressor 1 comprises a discharge duct 6. In an embodiment, the discharge duct 6 is made up of a cylinder 2 with variable flow cross section, communicating with a discharge chamber 600. In an embodiment, the discharge duct 6 communicates with discharge fittings without passing by way of the discharge chamber 600. In an embodiment, the discharge duct 6 comprises a discharge space 6A.

The discharge duct 6 has an inside surface and an outside surface. The inside surface of the discharge duct 6 is the surface that faces the discharge space 6A of the discharge duct 6. The outside surface is the surface opposite the inside surface. In an embodiment, the second end of the discharge duct 6 opens onto the cylinder 2 defining a discharge port 7. The discharge port 7 is the contact surface between the discharge space 6A and the internal space 2A of the cylinder 2.

In an embodiment, the compressor 1 comprises an intake valve 8. In an embodiment, the intake valve 8 is a pressure-regulated plate valve. In other words, when the pressure gradient between a gas downstream of the intake valve 8 and a gas upstream of the intake valve 8 exceeds a certain value, the intake valve 8 is automatically opened, allowing gas into the internal space 2A of the cylinder 2. In an embodiment, the pressure is regulated through an elastic element.

In an embodiment, the compressor 1 comprises a discharge valve 9. In an embodiment, the discharge valve 9 is a pressure-regulated plate valve. In other words, when the pressure gradient between a gas downstream of the discharge valve 9 and a gas upstream of the discharge valve 9 exceeds a certain value, the discharge valve 9 is automatically opened, allowing gas out of the internal space 2A of the cylinder 2. In an embodiment, the pressure is regulated through an elastic element.

Apart from the specific constructional differences between the intake valve 8 and the discharge valve 9, which are not an object of this disclosure, the discharge valve 9 and the intake valve 8 are reflections of each other in terms of assembly and certain geometrical aspects. For this reason, some of the features of the intake valve 8 and of the discharge valve 9 are described with reference to a generic "valve 10", meaning by that the intake valve 8 or the discharge valve 9 without distinction. We may observe that what has just been stated for the intake valve 8 and the discharge valve 9 also applies to the intake duct 4 and the discharge duct 6. For this reason, some of the features of the intake duct 4 and of the discharge duct 6 are described with reference to a generic "duct 60", meaning by that the intake duct 4 or the discharge duct 6 without distinction. With regard also to the intake space 4A and the discharge space 6A, both of these are hereinafter in this specification denoted without distinction by the term "sweeping space 60C". Some of the features of the intake port 5 and of the discharge port 7 are described with reference to a generic "access port 70", meaning by that the intake port 5 or the discharge port 7 without distinction.

In an embodiment, each duct 60 comprises a first end 60A. In an embodiment, each duct 60 comprises a second end 60B.

In an embodiment, the sweeping space 60C is the internal space 2A inside the respective duct 60 included between the first end 60A and the second end 60B of the duct.

The valve 10 has an underside surface 10A and a top surface 10B. The underside surface 10A comprises an underside stop surface 10A'. The underside surface 10B comprises a top stop surface 10B'. In an embodiment, the underside stop surface 10A' and the top stop surface 10B' are not subjected to the pressure of the gas.

The valve 10 comprises a lateral surface 10C. In an embodiment, the lateral surface 10C is parallel to the inside surface of the duct 60. In an embodiment, the lateral surface 10C is inclined to the inside surface of the duct 60.

In an embodiment, the compressor 1 comprises a blocking unit 100 for each valve 10. In an embodiment, the function of the blocking unit 100 is to block the respective valve 10 at its operating position. This operating position may vary along the longitudinal axis X of the duct 60.

In an embodiment, the compressor 1 comprises a dead space. The dead space is the sum of the volumes of gas which remains trapped in the compressor 1 after a compression stage.

In an embodiment, each valve 10, when it is at its operating position in the sweeping space 60C of the respective duct 60, has an "under valve space 1 1 ". The under valve space 1 1 is a part of the dead space of the compressor 1 .

The under valve space 1 1 is the part of the sweeping space 60C of the duct 60 between the respective valve 10 and the respective access port 70.

In an embodiment, each blocking unit 100 comprises an abutment surface 100A. In an embodiment, the abutment surface 100A is configured to come into contact with the underside stop surface 10A' of each valve 10. In an embodiment, an inner perimeter of the abutment surface 100A must intercept the underside stop surface 10A' of each valve 10. In an embodiment, the abutment surface 100A is perpendicular to the longitudinal axis X of the respective duct 60. In an embodiment, the abutment surface 100A is inclined to the longitudinal axis X of the duct 60 at an angle of less than ninety degrees. The abutment surface 100A allows stopping the valve 10 from sliding in an insertion direction I oriented from the first to the second end of the respective duct 60.

In an embodiment, each blocking unit 100 comprises a blocking member 100B. In an embodiment, each blocking member 100B is configured to come into contact with the top stop surface 10B' of the respective valve 10. In an embodiment, each blocking member 100B is configured to apply pressure on the top stop surface 10B' of the respective valve 10. In an embodiment, each blocking member 100B is a cylindrical body which is geometrically shaped to slide inside the respective duct 60. In an embodiment, each blocking member 100B is a cylindrical body which is geometrically shaped to be connected to the respective duct 60.

In an embodiment, each blocking member 100B comprises a first end 100B'. In an embodiment, each blocking member 100B comprises a second end 100B".

In an embodiment, the first end 100B' of each blocking member 100B is configured to come into contact with the top stop surface 10B' of the respective valve 10. In an embodiment, the second end 100B" of each blocking member 100B is configured to be connected to the respective duct 60. The blocking member 100B is configured to prevent the respective valve 10 from moving in an extraction direction E oriented from the second end 60B to the first end 60A of the respective duct 60.

In an embodiment, each duct 60 comprises a first stretch 601 . In an embodiment, each duct 60 comprises a second stretch 602. The first stretch 601 and the second stretch 602 of the duct 60 are each characterized by a flow cross section. In an embodiment, the flow cross section of the first stretch 601 of the duct is greater than the flow cross section of the second stretch 602 of the duct.

The difference between the flow cross section of the first stretch 601 of the duct and the flow cross section of the second stretch 602 of the duct defines a shoulder. By shoulder is meant a surface that is not parallel to a direction of insertion of the valve 10. In an embodiment, the non- parallelism between each shoulder and the direction of insertion ensures that the respective valve 10 butts against the shoulder of the respective duct 60.

In an embodiment, the flow cross section of the first stretch 601 of the duct is greater than the top surface 10B of the respective valve 10 so as to allow inserting the valve 10. In an embodiment, the flow cross section of the second stretch 602 of the duct must be smaller than the underside surface 10A of the respective valve 10. This allows stopping the respective valve 10 when it has been inserted as far as its operating position.

In an embodiment, each blocking unit 100 comprises an abutment bush 100A'. In an embodiment, the abutment bush 100A' is a cylindrical element which is geometrically shaped to slide inside the respective duct 60 until it butts against the shoulder of the respective duct 60. In an embodiment, each abutment bush 100A' is removably interposed between the shoulder of the respective duct 60 and the respective valve 10. In an embodiment, each abutment bush 100A' has a first circular crown and a second circular crown. In an embodiment, the first circular crown of each adjustment bush 100A' is configured to butt against the shoulder of the respective duct 60. In an embodiment, the second circular crown of each adjustment bush 100A' is configured to come into abutment against the respective valve 10, to define the abutment surface 100A.

In an embodiment, the abutment bush 100A' of one valve 10 of the reciprocating compressor 1 has, along the longitudinal axis X, a longitudinal extension h which is different from the longitudinal extension h of the abutment bush 100A' of another valve 10 of the reciprocating compressor 1 . In an embodiment, the under valve space 1 1 of one valve 10 of the reciprocating compressor 1 is different from the under valve space 1 1 of another valve 10 of the reciprocating compressor 1 .

In an embodiment, each blocking unit 100 comprises an adjustment bush 12. In an embodiment, each adjustment bush 12 comprises a first circular crown and a second circular crown. In an embodiment, the adjustment bush 12 is interposed between the blocking member 100B of the respective blocking unit 100 and the respective valve 10. In this embodiment, the first circular crown of each adjustment bush 12 butts against the top stop surface 10B' of the respective valve 10. In this embodiment, the second circular crown of each adjustment bush 12 comes into abutment against the second end 100B" of the blocking member. Since the total length of each duct 60 is fixed, the abutment surface 100A of the respective blocking unit 100 must be adapted as a function of the adjustment bush 12.

In an embodiment, the adjustment bush 12 is interposed between the shoulder of the respective duct 60 and the respective valve 10. In this embodiment, the adjustment bush 12 coincides with the abutment bush 100A'.

In an embodiment, the adjustment bush 12 is interposed between the shoulder of the respective duct 60 and the abutment bush 100A'.

In an embodiment, the adjustment bush 12 is interposed between the abutment bush 100A' of the respective blocking unit 100 and the respective valve 10. In this embodiment, the first circular crown of each adjustment bush 12 butts against the abutment bush 100A' of the respective blocking unit 100. In this embodiment, the second circular crown of each adjustment bush 12 comes into abutment against the underside stop surface 10A' of the respective valve 10. Since the total length of each duct 60 is fixed, the blocking member 100B of the respective blocking unit 100 must be adapted as a function of the adjustment bush 12.

In an embodiment, the inside surface of the duct 60 is smooth. In an embodiment, the inside surface of the duct 60 is completely smooth. In an embodiment, the inside surface of the duct 60 comprises a fastening thread 603.

In an embodiment, the outside surface of the duct 60 is smooth. In an embodiment, the fastening thread 603 is located on the outside surface of the duct 60.

In an embodiment, the duct 60 comprises a fastening flange on its first end 60A. In an embodiment, the fastening flange extends radially relative to the longitudinal axis X of the duct 60. In an embodiment, the fastening flange comprises a plurality of fastening holes 604 configured to be coupled to connecting elements such as, for example but not limited to, screws and bolts. In an embodiment, the first end 60A of the duct comprises a plurality of fastening holes 604 configured to be coupled to the connecting elements.

In an embodiment, the first end of each blocking member 100B comprises a plurality of connecting holes 101 B configured to be coupled to connecting elements such as, for example but not limited to, screws and bolts. In an embodiment, the plurality of fastening holes 604 and the plurality of connecting holes 101 B are configured to receive the same connecting element, so as to join together the blocking member 100B and the respective duct 60.

In an embodiment, the first end of each blocking member 100B comprises a connecting thread 103B. In an embodiment, the connecting thread 103B is on the inside surface of the respective blocking member 100B. In an embodiment, the connecting thread 103B is on the outside surface of the respective blocking member 100B. In an embodiment, each blocking member 100B comprises a connecting flange 102B. In an embodiment, the connecting flange 102B is on the first end 100B' of the respective blocking member 100B. In an embodiment, the connecting thread 103B is on the outside surface of the connecting flange 102B of the respective blocking member 100B.

In an embodiment, the connecting thread 103B and the fastening thread 603 are configured to be coupled to each other, thus joining the blocking member 100B to the respective duct 60.

In an embodiment, each blocking member 100B comprises a plurality of components which, in the operating configuration, butt against each other to define the longitudinal extension h of each blocking member 100B. In this embodiment, each blocking member 100B comprises at least a first component 104B configured to butt against the top stop surface 10B' of the valve 10 and a second component 105B configured to be joined to the respective duct 60.

In this embodiment, the first end of each blocking member 100B is on the second component 105B. In this embodiment, the second end of each blocking member 100B is on the first component 104B.

In an embodiment, each connecting flange 102B is on the second component 105B' of the respective blocking member 100B.

In an embodiment, the second component 105B of each blocking member 100B comprises a ring gasket, interposed between the second component

105B of each blocking member 100B and the inside surface of the respective duct 60.

In an embodiment, the second component 105B of each blocking member 100B is a plug which prevents the fluid in the respective duct 60 from escaping.

In this embodiment, each blocking member 100B comprises side passages 106B. In an embodiment, each duct 60 comprises side openings 60D. That way, during intake or discharge, the fluid flows into the intake chamber 400 or out of the discharge chamber 600 through the side openings 60D of the respective duct 60 and through the side passages 106B of the respective blocking member 100B.

In an embodiment, the compressor 1 comprises a crosshead 13. In an embodiment, the compressor 1 comprises an additional intake duct 4', defining an additional intake space 4A' and having a first end and a second end which is open to the internal space 2A of the cylinder 2 to define an additional intake port 5'.

In an embodiment, the additional intake port 5' is in contact with the same intake chamber 400 as the intake port 5.

In an embodiment, the compressor 1 comprises an additional discharge duct 6', defining an additional discharge space 6A' and having a first end and a second end which is open to the internal space 2A of the cylinder 2 to define an additional discharge port 7'.

In an embodiment, the compressor 1 comprises an additional intake valve 8' disposed in the additional intake duct 4' and spaced from the additional intake port 5'.

In an embodiment, the compressor 1 comprises an additional discharge valve 9' disposed in the additional discharge duct 6' and spaced from the additional discharge port 7'.

In an embodiment, the compressor 1 is configured to compress a fluid both by the sliding of the piston 3 in a going direction A oriented from the additional intake port 5' to the intake port 5, and by the sliding of the piston

3 in a return direction R from the intake port 5 to the additional intake port

5'. In this embodiment, for the same diameter and stroke of the piston 3, the flow processable by the compressor 1 increases.

The features described above in connection with the intake valve 8 or discharge valve 9, the intake duct 4 or discharge duct 6, the intake space

4A or discharge space 6A and the intake port 5 or discharge port 7, with reference to the terms valve 10, duct 60, sweeping space 60C and access port 70 apply without distinction also to the additional intake valve 8' or additional discharge valve 9', to the additional intake duct 4' or additional discharge duct 6', to the additional intake space 4A' or additional discharge space 6A' and to the additional intake port 5' or additional discharge port 7'.

Below is a description of a method for making a reciprocating compressor 1 . The compressor has an intake duct 4 and a discharge duct 6 having one or more of the features described above.

In the following description of the method, reference is generically made to a duct 60 in which a valve 10 is positioned, meaning that:

i) that duct 60 is the intake duct 4 and the valve 10 is the intake valve 8; or ii) that duct 60 is the discharge duct 6 and the valve 10 is the discharge valve 9.

Furthermore, the method according to the disclosure can be applied both to the intake valve 8 and to the discharge valve 9.

In the following description of the method, reference is generically made to a sweeping space 60C which can be accessed through an access port 70, meaning that:

i) the sweeping space 60C is the intake space 4A and the access port 70 is the intake port 5; or

ii) the sweeping space 60C is the discharge space 6A and the access port 70 is the discharge port 7.

In an embodiment, the method comprises a step of providing a cylinder 2 defining an internal space 2A.

In an embodiment, the method comprises a step F1 of providing a duct defining a sweeping space 60C and having a first end 60A and a second end 60B which is open to the internal space 2A of the cylinder 2 to define an access port 70. In an embodiment, a gas flows out of or into the duct 60 from an intake chamber 400 or from a discharge chamber 600 as a function of the type of duct 60. In an embodiment, the gas flows out of or into the duct 60 through side openings 60D. In an embodiment, the gas flows out of or into the duct 60 through the first end 60A of the duct 60. In an embodiment, the method comprises a step of providing a valve 10 disposed in the duct 60 and spaced from the access port 70. In an embodiment, the valve 10 opens when the difference between the pressure upstream and the pressure downstream of the valve 10 exceeds a threshold value. The valve 10 opens because this pressure difference exceeds the value of the force applied by a spring on a plate of the valve 10. Under the action of the pressure, the plate rises and allows the fluid to flow through.

In an embodiment, the method comprises a step of calculating a dead space. The calculation of the dead space takes into account the technical specifications which the buyer of a compressor 1 requires of the manufacturer of the compressor 1 The dead space is sized mainly as a function of the flow specified by the buyer.

In an embodiment, calculating the dead space comprises a step of calculating the under valve space 1 1 formed by a stretch of the sweeping space 60C, which is delimited by the valve 10 and the access port 70. The under valve space 1 1 depends on a trend of a flow cross section along a longitudinal axis X of the duct 60 and on the distance of the valve 10 from the access port 70.

In an embodiment, the method comprises a step of deriving a valve distance of the valve 10 as a function of the under valve space 1 1 , the valve distance being the distance by which the valve 10 is spaced from the access port 70 along the longitudinal axis X of the valve.

In an embodiment, the method comprises a step F2 of providing (or defining) an abutment surface 100A. In an embodiment, the method comprises a step F2 of defining an abutment surface 100A perpendicular to the longitudinal axis X of the duct 60. In an embodiment, the abutment surface 100A is defined at the valve distance of the valve 10 from the access port 70. In an embodiment, the abutment surface 100A butts against the valve 10 in an insertion direction I oriented from the first end to the second end 60B of the duct 60.

In an embodiment, the abutment surface 100A is defined at an initial stage in the production of the compressor 1 . This initial stage in the production of the compressor 1 comprises operations such as casting, machine processes, stock removal processes, laser processes and any other processes used in the prior art to make changes to a mechanical part. In an embodiment, defining the abutment surface 100A at an initial production stage is accomplished by reaming the duct 60. In this embodiment of the method, the duct 60 is reamed to create at least a first stretch 601 and a second stretch 602 characterized by different inside diameters, hence different flow cross sections. The term "reaming" is used to mean any machining process by which material is removed from an inside surface of the duct 60 to increase the internal diameter of a specific stretch of the duct 60. The difference between the flow cross sections of the two stretches of the duct 60 defines a shoulder. In one embodiment, the shoulder defines the abutment surface 100A.

In another embodiment, the step of defining the abutment surface 100A at an initial stage of production is accomplished by casting. In this embodiment, a casting mould is designed in such a way that the first and second stretches 601 and 602 of the duct 60 are formed directly in the mould. In this embodiment, the shoulder is preformed on the duct 60 and only fine machining processes are necessary to obtain dimensional tolerances to design specifications. In one embodiment, the shoulder defines the abutment surface 100A.

In another embodiment, the step of defining the abutment surface 100A is accomplished by assembling the compressor 1 . In this embodiment, the duct 60 comprises the shoulder, created according to one of the two embodiments described above.

In an embodiment, the step F2 of defining the abutment surface 100A is a step F2' of inserting an abutment bush 100A' into the duct 60. The abutment bush 100A' is inserted into the duct 60 in the insertion direction I until it comes into abutment against the shoulder of the duct 60. In an embodiment, a first circular crown of the abutment bush 100A' comes into abutment against the shoulder during the step F2' of inserting the abutment bush 100A'.

In this embodiment, a second circular crown of the abutment bush 100A' defines the abutment surface 100A.

In an embodiment, the method comprises a step F3 of inserting the valve 10 into the duct 60. The valve 10 slides in the insertion direction I until it butts against the abutment surface 100A. The valve 10 slides in the insertion direction I until its underside stop surface 10A' butts against the abutment surface 100A. In an embodiment, the valve 10 is inserted into the duct 60 by translating along the longitudinal axis X and rotating about the longitudinal axis X. This rototranslation facilitates insertion into the duct 60.

In an embodiment, the method comprises a step F4 of blocking the valve 10 by means of a blocking member 100B. In the step of blocking, the blocking member 100B abuts against the valve 10 to prevent it from moving in an extraction direction E oriented from the second end 60B to the first end 60A of the duct 60.

In an embodiment, the step F4 of blocking the valve 10 comprises a step of inserting the blocking member 100B into the duct 60. The step of inserting ends when a second end 100B" of the blocking member 100B comes into abutment against the valve 10.

In one embodiment, where the blocking member 100B is a single element, the step of inserting the blocking member 100B into the duct 60 comprises a single step of inserting.

In another embodiment, where the blocking member 100B comprises a plurality of elements, the step of inserting the blocking member 100B into the duct 60 comprises a plurality of steps of inserting, one for each element of the plurality of elements making up the blocking member 100B. In an embodiment, a first element 104B of the blocking member 100B comes into contact with the valve 10.

In an embodiment, the method comprises a step F4' of connecting the blocking member 100B to the duct 60. In an embodiment, the method comprises a step F4' of connecting the first end 100B' of the blocking member to the duct 60. In an embodiment the step F4' of connecting connects the first end 100B' of the blocking member to the first end 60A. of the duct.

In an embodiment, the step F4' of connecting the blocking member 100B comprises a step F4" of bolting by which a connecting flange 102B of the blocking member 100B is connected to a fastening flange of the duct 60. In an embodiment, the step F4' of connecting the blocking member 100B comprises a step F4" of bolting by which a connecting flange 102B of the blocking member 100B is connected to the first end 60A of the duct 60. In an embodiment, where the blocking member 100B comprises a second element 105B, the step of connecting joins the connecting flange 102B, located on the second element 105B, to the first end 60A of the duct 60. In an embodiment, where the blocking member 100B has side passages 106B and the duct 60 has side openings 60D, the second element 105B prevents the fluid from flowing into the first end 60A of the duct.

In an embodiment, the step F4' of connecting the blocking member 100B comprises a step of screwing by which a connecting thread 103B of the blocking member 100B is connected to a fastening thread 603 of the duct 60. In an embodiment, the step of screwing connects an outside surface of the duct 60. In an embodiment, the step of screwing connects an inside surface of the duct 60. In an embodiment, where the duct 60 comprises a third stretch whose flow cross section is different from those of the first and second stretches, the step of screwing connects the inside surface of the duct 60 at the third stretch.

This specification is also intended to cover a method for in-service adjustment of a reciprocating compressor 1 . This need, which may arise when external conditions change, may be satisfied by minor maintenance operations, and not massive operations, on the compressor 1 .

In one embodiment, the method comprises a step of adjusting.

In an embodiment, the step of adjusting comprises a step of disassembling and extracting the blocking member 100B. In an embodiment, the step of adjusting comprises a step of extracting the valve 10. In an embodiment, the step of adjusting comprises a step of extracting the abutment bush 100A'.

In an embodiment, the step of adjusting comprises a step of extracting the adjustment bush 12. In an embodiment, the step of adjusting comprises a step of adapting or replacing the blocking member 1 00B as a function of the longitudinal extension h of the adjustment bush 12. In an embodiment, the step of adapting is a step of inserting an additional element added to the plurality of elements making up the blocking member 100B so as to modify the total longitudinal extension h of the blocking member 100B. In an embodiment, the step of adapting is a step of inserting an additional element between the first element 105A and the second element 105B. In an embodiment, the step of adapting comprises a step of replacing the abutment bush 100A' as a function of the longitudinal extension h of the adjustment bush 12.

In an embodiment, the step of inserting the adjustment bush 12 is a step of inserting it between the shoulder of the duct 60 and the abutment bush 100A'.

In an embodiment, the step of inserting the adjustment bush 12 is a step of inserting it between the shoulder of the duct 60 and the valve 10.

In an embodiment, the step of inserting the adjustment bush 12 is a step of inserting it between the abutment bush 100A' and the valve 10.

In an embodiment, the step of inserting the adjustment bush 12 is a step of inserting it between the valve 10 and the blocking member 100B.

In an embodiment, the step of adjusting comprises a step of progressively reinserting adapted components. By "adapted components" is meant the abutment bush 100A' and the blocking member 100B whose longitudinal extensions have been adapted as a function of the longitudinal extension h of the adjustment bush 12.

In an embodiment, the method comprises a step of providing one or more additional ducts forming a plurality of ducts 60, each defining a respective sweeping space 60C and having a first end and a second end which is open to the internal space 2A of the cylinder 2 to define a respective access port 70.

In an embodiment, the method comprises a step of providing one or more additional valves forming a plurality of valves 10, each disposed in the respective duct 60 and spaced from the respective access port 70.

In an embodiment, the method comprises a step of calculating the dead space. In this embodiment, the dead space includes, for each valve 10, the respective under valve space 1 1 , formed by a stretch of the sweeping space 60C, of the respective duct 60, which is delimited by the respective valve 10 and by the respective access port 70.

In an embodiment, the method comprises a step of deriving the valve distance of the valve 10, as a function of the respective under valve space 1 1 , the valve distance being the distance of each valve 10 from the access port 70 of the respective duct 60 along the longitudinal axis X.

In an embodiment, the method comprises a step of defining the respective abutment surface 100A of the valve 10 at the respective valve distance from the respective access port 70.

In an embodiment, the method comprises a step of inserting each valve 10 into the respective duct 60 until it comes into abutment with the respective abutment surface 100A. In an embodiment, each abutment surface 100A butts against the valve 10 in an insertion direction I.

In an embodiment, the method comprises a step of blocking each valve 10. In an embodiment, the method comprises a step of blocking each valve 10 using the respective blocking member 100B. In an embodiment, each blocking member 100B abuts against the respective valve 10 to prevent it from moving in the extraction direction E.

In an embodiment, the step of calculating the valve distance for each valve 10 of the plurality of valves is carried out by running an algorithm on a fluid dynamic simulator.

In an embodiment, the step of calculating the valve distance for each valve 10 of the plurality of valves comprises a step of experimental determination.

The step of experimental determination comprises a plurality of experimental tests whereby a thermodynamic efficiency is determined for a given distribution of the dead space. At the end of each test, the distribution of the dead space is modified and the next test is carried out. At the end of a certain number of tests, the thermodynamic efficiency function is interpolated with respect to the distribution of the dead space, hence the extent of each valve distance.

Lastly, determining the function maximum makes it possible to determine the optimum configuration of the valves to minimize the negative effects on the thermodynamic efficiency.