DESCRIPTION

Field of the invention

The invention relates to a plunger pump / plunger motor comprising a motor casing having a first cylindrical chamber and a plunger movable in this chamber with a drive shaft attached to a first plunger side, so that the plunger surface on the first side is smaller than on an opposite second side, a first and a second hole being provided in the motor casing at such a location that in any position of the plunger one hole is available on either side of the plunger, and which plunger pump / plunger motor comprises a valve including a valve casing having a second cylindrical chamber and a control valve movable in this chamber, which valve can establish a communication between a connecting hole for a delivery pipe and the second hole.

In case of a plunger motor the drive shaft drives for example a mechanism that converts a translating movement into a rotating movement, and in case of a plunger pump the drive shaft drives for example a piston that provides the pumping action.

State of the art

A plunger pump / plunger motor of this type is generally known. In the known plunger pump / plunger motor the valve has a separate power supply for the purpose of moving the control valve.

Summary of the invention

It is an object of the invention to provide a plunger pump / plunger motor of the type defined in the opening paragraph, which is simpler than the known plunger pump / plunger motor. To this end the plunger pump / plunger motor according to the invention is characterized in that the valve casing has a first further hole and a second further hole at such a location that in any position of the control valve one further hole is available on either side of the control valve, while furthermore the motor casing has a third and a fourth hole, where the third hole communicates with the first further hole in the valve casing and the fourth hole communicates with the second further hole in the valve casing, which third and fourth holes can alternately be brought into communication with the connecting hole for the delivery pipe by the plunger. The operation of the valve in the plunger pump / plunger motor according to the invention does not require external power supply, but this valve is fed by the same delivery pipe as the one for feeding the plunger motor, so that a simple construction is obtained.

The plunger pump / plunger motor according to the invention is pre-eminently suitable for circulating boiling liquids. Boiling liquids are often circulated by means of rotating pumps (centrifugal and side channel or a combination thereof) which are coupled to an electric drive motor. Owing to the injurious effect of the liquid to be circulated on humans and the environment, the coupling between pump and motor is to be leak-proof. These are usually costly and wear- sensitive solutions which have dismal efficiency. Alternatively, so- called pumper drums are utilized, which are called montejus in process technology. For circulating the liquid, compressed gas or flash gas is then used in lieu of compressed air. A disadvantage of this solution is that many fittings are needed, that the solution is energetically poor and that delivery is effected periodically.

The plunger pump / plunger motor according to the invention provides a cost effective solution for circulating boiling liquids with:

1. minimum energy consumption

2. minimum NPSH value; and

3. possibility of being maintenance free.

Condition 1 is satisfied by making use of a flash gas fed expander motor, condition 2 is satisfied by minimizing the flow losses in the pump and condition 3 is satisfied by striving for a minimum number of component parts (hence also the low cost price) which move with little friction.

An embodiment of the plunger pump / plunger motor according to the invention is characterized in that the third and the fourth hole are alternately brought into communication with the environment or with a connecting hole for a delivery pipe by the plunger, so that no further provisions need to be made for this.

Preferably, the motor casing further has a fifth and a sixth hole which communicate with the environment or with the connecting hole for the delivery pipe and the plunger can alternately establish a communication between the third and the fourth hole and the fifth and the sixth hole. Furthermore, the plunger pump / plunger motor is preferably constructed such that the control valve can establish a communication between the second hole and the environment or the connecting hole for the delivery pipe.

The valve casing preferably has a third further hole which communicates with the environment or with the connecting hole for the delivery pipe and the control valve can establish a communication between the second hole and the third further hole.

An embodiment of the plunger pump / plunger motor according to the invention in which this embodiment is arranged as a plunger pump is characterized in that the drive shaft is connected to a further plunger which is movable in a third cylindrical chamber which is located in a pump casing in which a suction hole / delivery hole is present.

Preferably, the control valve can alternately be brought into communication with a connecting hole for a suction pipe and the connecting hole for the delivery pipe.

A further embodiment of the plunger pump / plunger motor according to the invention is characterized in that the valve casing is provided with a fourth further hole which communicates with the suction hole /delivery hole, as well as a fifth further hole which communicates with the connecting hole for a suction pipe.

A still further embodiment of the plunger pump / plunger motor according to the invention is characterized in that the third further hole communicates with the connecting hole for a delivery pipe.

A compact and simple construction of the plunger pump / plunger motor according to the invention is characterized in that the motor casing and valve casing are constituted by a single block which accommodates the first and the second cylindrical chamber, and which block is provided with at least a single connecting hole to which the delivery pipe can be connected, as well as channels which connect the holes and further holes to each other and to the at least one connecting hole.

A further compact and simple construction of the plunger pump / plunger motor according to the invention is characterized in that the block also constitutes the pump casing and is provided with two further connecting holes to which the suction pipe and the delivery pipe can be connected.

An even simpler construction of the plunger pump / plunger motor according to the invention is characterized in that the plunger and the further plunger are attached to each other. Brief description of the drawings.

The invention will be elucidated more fully hereinbelow based on examples of embodiment of the plunger pump / plunger motor according to the invention while reference is made to the appended drawing figures, in which:

Fig. 1 shows a first embodiment of the plunger pump / plunger motor according to the invention arranged as a plunger pump at the end of the suction stroke;

Fig. 2 shows the situation shown in Fig. 1 with a switched-over control valve;

Fig. 3 shows the plunger pump / plunger motor at the end of the delivery stroke;

Fig. 4 shows the situation shown in Fig. 3 with switched-over control valve; and

Fig. 5 shows a second embodiment of the plunger pump / plunger motor according to the invention arranged as a plunger motor.

Detailed description of the drawings

Figs. 1 to 4 show a first embodiment of the plunger pump / plunger motor according to the invention arranged as a plunger pump shown in different stages of the pumping proces. The plunger pump / plunger motor comprises a motor casing 1A which accommodates a first cylindrical chamber 7 and a plunger 2 movable in this chamber. To a first side A of the plunger 2 is attached a drive shaft 19, as a result of which the plunger surface on this first side A is smaller than on an opposite, second side B.

The motor casing 1A is provided with a first hole and a second hole Oi and 0 ₂ at such a location that in any position of the plunger 2 one hole is available on either side of the plunger.

The plunger pump / plunger motor further comprises a valve which has a valve casing IB wich accommodates a second cylindrical chamber 7B and a control valve 3 movable in this chamber. This control valve can provide that a connecting hole 6 for a delivery pipe communicates with the second hole 0 ₂ .

The valve casing IB is provided with a first further hole and a second further hole Fi and F ₂ . These further holes are located at such a spot that in any position of the control valve 3 one further hole is available on either side of the control valve. The motor casing 1A is further provided with a third and a fourth hole 0 ₃ and O4. The third hole 0 ₃ communicates with the first further hole Fi in the valve casing, and the fourth hole 0 ₄ communicates with the second further hole F ₂ in the valve casing. The third and fourth holes O3 and 0 ₄ can alternately be brought into communication with the connection 6 for the delivery pipe by the plunger 2.

The connection 6 for the delivery pipe is in permanent communication with the first hole 0 _\ . The third and fourth holes 0 ₃ and 0 ₄ can alternately be brought into communication with a connecting hole 5 for the delivery pipe by the plunger 2.

The motor casing 1 A is further provided with a fifth and a sixth hole O5 and 0 ₆ which communicate with the connecting hole 5 for the delivery pipe. The third and the fourth hole O3 and 0 ₄ can alternately be brought into communication with the fifth and sixth hole O5 and 0 ₆ respectively by the plunger 2. The control valve 3 can establish a communication between the second hole 0 ₂ and the connecting hole 5 for the delivery pipe.

The valve casing IB is provided with a third further hole F3 which communicates with the connecting hole 5 for the delivery pipe. The drive shaft 19 is connected to a further plunger 2a which is movable in a third cylindrical chamber 8 which is accommodated in a pump casing 1C in which a suction/delivery hole 9 is present.

The control valve 3 can alternately establish a communication between the suction hole /delivery hole 9 and a connecting hole 4 for a suction pipe and a connecting hole 5 for a delivery pipe. The valve casing IB is provided with a fourth further hole F ₄ which communicates with the suction hole / delivery hole 9, as well as a fifth further hole F5 which communicates with the connecting hole 4 for the suction pipe. The third further hole F3 communicates with the connecting hole 5 for the delivery pipe.

The motor casing 1A, the valve casing IB and the pump casing 1C are constituted by a single block 1 in which the first, the second and the third cylindrical chambers 7, 7B and 8 are located. This block 1 is provided with three connecting holes 4, 5 and 6 to which the suction pipe, the delivery pipe and the pressure pipe can be connected. In the block 1 are provided channels 12, 13, 16 and 17 which connect the holes Oi, 0 ₂ , O3, 0 ₄ , O5 and 0 ₆ and further holes Fi, F ₂ , F3 and F ₄ to each other and to the three connecting holes. The plunger 2 and the further plunger 2a constitute a whole.

The plunger pump / plunger motor comprises no more than two moving parts, that is to say, the plunger 2 with attached to it the further plunger 2a, and the control valve 3. The plunger 2 with the further plunger 2a attached to it is constituted by two parts, on the left there is the pumping part 2a and 2b and on the right there is the motor part 2c and 2d. The plunger and the control valve are coupled hydraulically, thus complex mechanisms and mechanisms subject to wear are absent.

The ratio of pump diameter to motor diameter determines the lift of the pump and/or the number of strokes, thus the pump flow rate. The higher the difference in pressure over the motor with equal pump lift, the higher the pump flow rate.

The feed of the motor takes place through the connecting hole 6 by means of a medium that has a higher pressure than the pump pressure. This may be liquid, gas or a biphase mixture.

Hereinbelow the operation of the plunger pump / plunger motor will be further elucidated with reference to the Figs. 1 to 4. In Fig. 1 the position of the control valve 3 and plunger 2 is shown substantially at the end of the suction stroke at the moment where the control valve 3 is going to be changed over and the slot 2b in plunger 2 starts to open the channel 12 so that a connection is created between channel 12 and channel 13 so that the pressure on the left hand side of the control valve 3 will decrease rapidly to the pump delivery pressure prevailing in the connecting hole 5 for the delivery pipe.

A little later the high pressure that prevails in the cylindrical chamber 7 (this chamber forms a hydropneumatic compression spring) comes through channel 16 to the right hand side of the control valve 3 and will switch the latter over in a rapid manner. Fig. 2 shows the situation in switched-over position.

Even before the motor side of the plunger 2 has reached its end position, there is already the higher pressure in channel 16 and the plunger will commence the delivery stroke. In the left hand position there is a constant higher pressure on the motor part of the plunger 2 through slot 3d in the control valve and the plunger 2 will push away the liquid in the cylindrical chamber 8 (this is the pump chamber) through the connecting hole 5 for the delivery pipe. By the end of the delivery stroke, see Fig. 3, the plunger 2 is decelerated because the plunger is to push away the liquid in chamber 11 through a narrow channel 10. If the plunger 2 passes the third hole 0 ₃ of channel 12, high-pressure medium will flow through the connecting hole 6 in the cylindrical chamber 7 (the compression spring) to the left hand side of the control valve 3. On the right hand side of the control valve 3 the pressure can be lowered through channel 15, slot 2d, channel 17 to the connection 5 for the delivery pipe.

The control valve 3 changes over (cf. Fig. 4) and will discharge the motor of the pressure by opening up the channel 16 through slot 3c and channel 13 to the connecting hole 5 for the delivery pipe where the pump delivery pressure prevails. The pressure in the cylindrical chamber 7 (compression spring) will now push the plunger 2 to the right and thus draw liquid into the cylindrical chamber 8 (pump chamber) through the connecting hole 4.

Disc 3 a functions as a change-over cock so as to have the liquid flow correctly during the suction stroke and delivery stroke. The discs 3b are used for balancing of pressure. For equalizing the chambers around these discs, the valve has a bore 3e.

Fig. 5 shows a second embodiment of the plunger pump / plunger motor according to the invention, arranged as a plunger motor this time. All parts similar to those of the first embodiment or having a similar function to those of the first embodiment are referred to by like reference numerals. Tn this embodiment the pump section is lacking and the drive shaft 19 extends to beyond the block 1. This drive shaft is driven by the plunger 2 and can in its turn drive a shaft for example via a slotted link mechanism. Furthermore, the third and fourth holes O3 and 0 ₄ can alternately be brought into communication with the environment 18 in lieu of with a connecting hole for a delivery pipe

Albeit the invention has been described in the foregoing with reference to the drawings, it should be observed that the invention is not by any manner or means restricted to the embodiment shown in the drawings. The invention also extends to all embodiments deviating from the embodiment shown in the drawings within the spirit and scope defined by the claims.