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Title:
CHECK VALVE ASSEMBLY FOR HYDRAULIC TENSIONERS
Document Type and Number:
WIPO Patent Application WO/2019/168495
Kind Code:
A1
Abstract:
A conduit plug for a hydraulic chain tensioner includes a plug passageway configured to communicate fluid from a primary fluid cavity to a secondary fluid cavity; an outer surface located radially outwardly from the plug passageway shaped to conform to a surface of a conduit plug bore formed in a housing of the hydraulic chain tensioner; an open end defined by the plug passageway; and a closed end that at least partially defines the plug passageway and is also configured to form an outwardly facing surface of the hydraulic chain tensioner and prevent the release of fluid from the conduit plug bore to the atmosphere. The conduit plug can also function as a valve seat for a check valve.

Inventors:
CARUGATI, Massimo (Via Don Cernuschi 16/A, Vimercate, (MB), IT)
Application Number:
US2018/019850
Publication Date:
September 06, 2019
Filing Date:
February 27, 2018
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
BORGWARNER INC. (3850 Hamlin Road, Auburn Hills, MI, 48326, US)
International Classes:
F16H7/08; F01L1/02; F02B67/06
Foreign References:
KR20020032377A2002-05-03
KR20160014642A2016-02-11
US20060089221A12006-04-27
US20030166428A12003-09-04
JP2012211645A2012-11-01
Attorney, Agent or Firm:
CICOTTE, Colin (Reising Ethington P.C, 755 West Big Beaver Road Suite 185, Troy MI, 48084, US)
Download PDF:
Claims:
What is claimed is:

1. A conduit plug for a hydraulic chain tensioner, comprising:

a plug passageway configured to communicate fluid from a primary fluid cavity to a secondary fluid cavity;

an outer surface located radially outwardly from the plug passageway and shaped to conform to a surface of a conduit plug bore formed in a housing of the hydraulic chain tensioner;

an open end defined by the plug passageway; and

a closed end that at least partially defines the plug passageway and is also configured to form an outwardly- facing surface of the hydraulic chain tensioner and prevent the release of fluid from the conduit plug bore to the atmosphere.

2. The conduit plug recited in claim 1, wherein the plug passageway further comprises one or more apertures located along an axial length of the plug passageway that extend from an inner surface of the plug passageway to an outer surface of the plug passageway.

3. The conduit plug recited in claim 1, further comprising a first flange extending radiallyoutwardly from one axial location along the plug passageway and a second flange extending radiallyoutwardly from another axial location along the plug passageway. 4. The conduit plug recited in claim 3, wherein the first flange and the second flange each includes a portion of the outer surface that conforms to a surface of the conduit plug bore.

5. The conduit plug recited in claim 1, further comprising an annular groove formed proximate the open end of the conduit plug in between the open end and the outer surface.

6. The conduit plug recited in claim 6, wherein the open end defines a fluid passage in fluid communication with a primary check valve that includes a plate releasably biased into abutting a valve seat of the conduit plug located in between the open end and the annular groove.

7. The conduit plug recited in claim 6, wherein the plate moves away from the valve seat in response to fluidic pressure exerted on the annular groove thereby permitting the flow of fluid into the plug passageway.

8. The conduit plug recited in claim 1, wherein the conduit plug includes a valve seat adjacent the open end that supports a primary check valve within the conduit plug bore.

9. A hydraulic chain tensioner, comprising:

a housing that includes one or more attachment points for connecting with an internal combustion engine, a piston bore, and a conduit plug bore;

a primary piston, including a primary cavity, that engages a primary spring;

a secondary piston received within the primary cavity of the primary piston that engages the primary spring and a secondary spring;

an inner sleeve having a closed end and an outer surface that is concentric with at least a portion of the secondary piston;

a conduit plug, received by the conduit plug bore, including an open end, a closed end, and a plug passageway configured to communicate fluid from a primary fluid cavity to a secondary fluid cavity through a primary check valve.

10. The hydraulic chain tensioner recited in claim 9, wherein the plug passageway further comprises one or more apertures located along an axial length of the plug passageway that extend from an inner surface of the plug passageway to an outer surface of the plug passageway.

11. The hydraulic chain tensioner recited in claim 9, wherein the conduit plug further comprises a first flange extending radiallyoutwardly from one axial location along the plug passageway and a second flange extending radially¬ outwardly from another axial location along the plug passageway.

12. The hydraulic chain tensioner recited in claim 11, wherein the first flange and the second flange each includes a radial outer surface that conforms to a surface of the conduit plug bore.

13. The hydraulic chain tensioner recited in claim 9, wherein the conduit plug further comprises an annular groove formed proximate the open end of the conduit plug in between the open end and an outer surface of the conduit plug.

14. The hydraulic chain tensioner recited in claim 9, wherein the open end defines a fluid passage in fluid communication with the primary check valve that includes a plate releasably biased into abutting a valve seat of the conduit plug located in between the open end and the annular groove.

15. The hydraulic chain tensioner recited in claim 14, wherein the plate moves away from the valve seat in response to fluidic pressure exerted on the annular groove thereby permitting the flow of fluid into the plug passageway.

16. The hydraulic chain tensioner recited in claim 9, wherein the conduit plug includes a valve seat adjacent the open end that supports the primary check valve within the conduit plug bore.

17. The hydraulic chain tensioner recited in claim 9, further comprising the primary check valve.

18. The hydraulic chain tensioner recited in claim 17, wherein the primary check valve further comprises a two-way check valve.

19. The hydraulic chain tensioner recited in claim 9, further comprising a secondary check valve. 20. The hydraulic chain tensioner recited in claim 9, further comprising a pressure relief valve.

Description:
CHECK VALVE ASSEMBLY FOR HYDRAULIC TENSIONERS

TECHNICAL FIELD

The present application relates to chain tensioners and, more particularly, to variable -force hydraulic chain tensioners.

BACKGROUND

Generally speaking, internal combustion engines (ICEs) use an endless loop to drive and control the rotation of a camshaft in relation to the rotation of a crankshaft. The endless loop, such as a timing chain, can vary in length according to a number of variables, such as temperature, rotational speed, and age. As a result, tensioners are used to maintain tension on the endless loop regardless of length. The tensioners include a piston, slidably received within a bore of a tensioner housing, that presses against the timing chain. The piston can be moved toward the endless loop by pressurized fluid from a fluid source. Fluid from the fluid source can flow through a check valve to a primary portion. As pressure in the fluid portion builds, the check valve may prevent the fluid from flowing back to the fluid source. Instead, fluid can escape from the tensioner and enter the atmosphere outside of the tensioner housing. A variable force tensioner is an enhancement of a traditional hydraulic tensioner and includes two pistons and two pressurized chambers. It would be helpful to include additional fluid passageways within the tensioner housing to feed fluid to both pressurized chambers and capture the escaping fluid. However, the creation of additional fluid passageways within the tensioner housing can add complexity to the chain tensioner.

SUMMARY

In one embodiment, a conduit plug for a hydraulic chain tensioner includes a plug passageway configured to communicate fluid from a primary fluid cavity to a secondary fluid cavity; an outer surface located radially outwardly from the plug passageway shaped to conform to a surface of a conduit plug bore formed in a housing of the hydraulic chain tensioner; an open end defined by the plug passageway; and a closed end that at least partially defines the plug passageway and is also configured to form an outwardly- facing surface of the hydraulic tensioner and prevent the release of fluid from the conduit plug bore to the atmosphere. In another embodiment, a hydraulic chain tensioner, comprises a housing that includes one or more attachment points for connecting with an internal combustion engine, an axial piston bore, a conduit plug bore, and one or more fluid passages fluidly communicating with the conduit plug bore; a primary piston, including a primary cavity, that engages a primary spring; a secondary piston received within the primary cavity of the primary piston that engages the primary spring and a secondary spring; an inner sleeve having a closed end and an outer surface that is concentric with at least a portion of the secondary piston; a piston check valve selectively permitting flow of fluid through an aperture in the closed end of the inner sleeve between a supply chamber and the axial piston bore; and a conduit plug including one or more fluid passages or apertures, configured to be received by the conduit plug bore, in fluid communication with the axial piston bore and the supply chamber.

In another embodiment, a hydraulic chain tensioner includes a housing that includes one or more attachment points for connecting with an internal combustion engine, a piston bore, and a conduit plug bore; a primary piston, including a primary cavity, that engages a primary spring; a secondary piston received within the primary cavity of the primary piston that engages the primary spring and a secondary spring; an inner sleeve having a closed end and an outer surface that is concentric with at least a portion of the secondary piston; a conduit plug, received by the conduit plug bore, including an open end, a closed end, and a plug passageway configured to communicate fluid from a primary fluid cavity to a secondary fluid cavity through a primary check valve. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a profile view depicting an implementation of a valve timing system of an internal combustion engine that uses a hydraulic tensioner;

Figure 2 is a cross-sectional profile view depicting an implementation of a hydraulic tensioner and a perspective view of an implementation of a conduit plug removed from the hydraulic tensioner;

Figure 3 is a cross-sectional perspective view depicting an implementation of a hydraulic tensioner;

Figure 4 is a perspective view of a cross-section of another implementation of a hydraulic tensioner; and

Figure 5 is another perspective view of a cross-section of another implementation of a hydraulic tensioner.

DETAILED DESCRIPTION

A hydraulic chain tensioner includes a high-pressure primary portion and a low-pressure secondary portion that fluidly communicate with each other through a conduit plug. Fluid can flow between the primary portion and the secondary portion through the conduit plug. The conduit plug is received by a conduit plug bore in the housing of the hydraulic chain tensioner. The conduit plug can be closed on one end and includes one or more fluid passages that permit fluid flow through a primary check valve to the primary portion. Fluid can eventually flow back from the primary portion to the conduit plug through passage holes formed in a check valve disk thereby returning to the secondary portion through the conduit plug. Fluid can also flow from the secondary portion through a secondary check valve and return to the primary portion.

In the past, fluid from the primary portion of the hydraulic chain tensioner could be released outside of the housing of the tensioner and into an engine atmosphere. The flow of fluid from a fluid source through the hydraulic chain tensioner to the atmosphere outside of the housing can increase consumption of fluid by the tensioner. In contrast, the hydraulic chain tensioner described here prevents the release of fluid outside of the housing and instead recycles fluid from the primary portion and communicates it to the secondary portion through passage holes in a check valve and the conduit plug.

Combining the conduit plug with the housing of the hydraulic chain tensioner can increase the ease with which fluid is recirculated within the hydraulic chain tensioner. A conduit plug bore can be a recess formed in the housing that opens to an exterior surface of the hydraulic chain tensioner and is shaped to closely conform to the outer surface(s) of the conduit plug. The conduit plug can be inserted into the conduit plug bore thereby creating seal that prevents fluid from escaping from the housing yet also serving as a fluid conduit inside of the housing. The conduit plug prevents the release of fluid outside of the housing but can communicate fluid between the primary portion and the secondary portion. The conduit plug can split or deviate fluid flow from the secondary portion so that fluid can be supplied or made available to both the primary portion and the secondary portion.

Turning to FIG. 1, an implementation of a valve timing system 10 of an internal combustion engine is shown. The ICE in this implementation includes two camshafts 12 and a crankshaft 14. Each of the camshafts 12 includes a camshaft sprocket 16 fixedly attached to a distal end and the crankshaft includes a crankshaft sprocket 18 fixedly attached to a distal end of the crankshaft. The camshaft sprockets 16 and crankshaft sprocket 18 each includes a plurality of radially- outwardly facing teeth 20 along an external surface. An endless loop 22, such as a timing chain or belt, can engage the radially- outwardly facing teeth 20 of the camshaft sprockets 16 and the crankshaft sprocket 18 communicating rotational force from the crankshaft sprocket 18 to the camshaft sprockets 16. The ICE uses a hydraulic tensioner assembly that includes a tensioning shoe 26 and a hydraulic tensioner 24 that tensions the endless loop 22 through the tensioning shoe 26. The tensioning shoe 26 can attach to the ICE at a pivot 28 and rotate about the pivot 28 to engage the endless loop 22 at an outer surface of the tensioning shoe 26. A piston 30 of the hydraulic tensioner 24 can engage an inner surface 34 of the tensioning shoe 26 and apply force to the tensioning shoe 26 toward the endless loop 22. One or more chain guides 36 can be attached to the ICE and help control motion of the endless loop 22. The chain guide(s) 36 can include one or more walls that extend outwardly from the ICE to control motion of the endless loop 22.

An implementation of the hydraulic tensioner 24 is shown in more detail in FIGS 2-5. The hydraulic chain tensioner 24 includes a housing 38 having an axially-extending piston bore 40, a conduit plug bore 42, and a pressure relief bore 44. A primary fluid cavity 46 communicates fluid from the piston bore 40 to the conduit plug bore 42 and a secondary fluid cavity 48 communicates fluid from the conduit plug bore 42 to the piston bore 40 thereby creating a pathway for recirculating fluid within the housing 38 of the hydraulic chain tensioner 24. A primary check valve 52 selectively permits the flow of fluid between the piston bore 40 included in the primary portion and a conduit plug 54 included in the secondary portion. Recirculated fluid flowing from the conduit plug 54 to the piston bore 40 can be regulated by a secondary check valve 56. In this implementation, a pressure relief valve 58 is in fluid communication with the piston bore 40 via the primary fluid cavity 42 permitting fluid exceeding a particular fluid pressure in the primary portion to escape to the secondary portion. However, other implementations of hydraulic chain tensioners may be implemented without a pressure relief valve.

The piston bore 40 receives a piston assembly 60 that axially slides within the piston bore 40. The piston assembly 60 includes a primary piston 62, a secondary piston 64, and an inner sleeve 66 that each move axially relative to each other. The primary piston 62, secondary piston 64, and the inner sleeve 66 exist in the primary portion of the hydraulic chain tensioner 24. Each of the primary piston 62, the secondary piston 64, and the inner sleeve 66 can include an open end and a closed end. The primary piston 62 defines a primary cavity 68 extending axially along the length of the primary piston 62 so that the primary cavity 68 includes an open end and a closed end. The closed end of the primary piston 62 can include a vent 69 that fluidly communicates between the primary cavity 68 and the atmosphere. The primary cavity 68 receives the secondary piston 64, the inner sleeve 66, a primary spring 70, and a secondary spring 72. The primary spring 70 has a higher spring rate (k) relative to the secondary spring 72 and can be positioned in the primary cavity 68 so that it abuts the closed end of the primary cavity 68. The inner sleeve 66 can be closed on one end and include an opening on another end creating an inner sleeve cavity 74 that receives the secondary piston 64 and permits the secondary piston 64 to slide axially within the inner sleeve cavity 74. The secondary piston 64 can be open on one end and closed at another end forming a secondary piston cavity 76 that receives the secondary spring 72. A vent 71 can be located in the closed end of the secondary piston 64 and fluidly communicate between the primary cavity 68 and the secondary piston cavity 76. The secondary spring 72 can abut the closed end of the secondary piston 64 and the closed end of the inner sleeve 66 when the inner sleeve cavity 74 receives the secondary piston 64 such that an outer surface 78 of the secondary piston 64 closely conforms to a surface of the inner sleeve cavity 74. The primary piston 62, the secondary piston 64, the inner sleeve 66, the primary spring 70, and the secondary spring 72 can be axially compressed within the piston bore 40. An aperture 80 in the closed end of the inner sleeve 66 permits fluid to pass between the primary portion and secondary portion of the hydraulic tensioner 10; the fluid flow is selectively controlled via the secondary check valve 56.

The conduit plug 54 that communicates fluid between the primary fluid cavity 46 and the secondary fluid cavity 48 through the secondary check valve 56 is received by the conduit plug bore 42 formed in the housing 38 of the hydraulic tensioner 24. In this implementation, the conduit plug bore 42 and the conduit plug 54 each have a generally annular shape. However, it should be appreciated that the conduit plug 54 and the conduit plug bore 42 can be implemented in a variety of different shapes. The conduit plug 54 includes a plug passageway 82 that communicates fluid from location to another location. The plug passageway 82 can include one or more apertures 84 located along an axial length that extend from an inner surface of the plug passageway 82 to an outer surface of the plug passageway 84. The plug passageway 84 can include an open end 86 as well as a closed end 88. The primary fluid cavity 46 is in fluid communication with the conduit plug bore 42 and the open end 86 of the plug passageway 82. A first flange 90 extends radially- outwardly from one location along the plug passageway 82 and second flange 92 extends radiallyoutwardly from another location along the plug passageway 82. The first flange 90 and the second flange 92 each includes a radial outer surface 94 that, when the conduit plug 54 is inserted in the conduit plug bore 42, closely conforms to the inner surface of the conduit plug bore 42 and inhibit fluid from passing between the radial outer surface 94 and a surface of the conduit plug bore 42. In some implementations, such is shown in FIGS. 2-3, the housing 38 can also include a primary check valve bore 53 having a different diameter than the conduit plug bore 42 that is formed between the primary fluid cavity 46 and the conduit plug bore 42. The primary check valve bore 53 can receive the primary check valve 52 that fluidly communicates between the primary fluid cavity 46 and the conduit plug 52 such that a surface of the valve 52 abuts a shoulder of the bore 53 and a shoulder of the conduit plug 52. However, in other implementations, the primary check valve 52 is received within the conduit plug bore 42.

After insertion into the housing 38, the conduit plug 54 secures the primary check valve 52 within the conduit plug bore 42 and prevents axial movement of the valve 52. The primary check valve 52 can be positioned in the conduit plug bore 42 such that it abuts a shoulder in the conduit plug bore 42 and a flow path of the primary check valve 52 is aligned with the primary fluid cavity 46. This is shown in more detail in FIGS. 4-5. The primary check valve 52 can include a base 55 having an annular flange 57 and a biasing member 59 that releasably biases a plate 61 into engagement with the plug passageway 82 of the conduit plug 54. In this implementation, the plate 61 is a cupped disk but other shapes are possible. The biasing member 59 can create axial force against the annular flange 57 and the plate 61 that urges the plate 61 into contact with the conduit plug 54.

A portion of the conduit plug 54 is shaped to create a valve seat 63 for the primary check valve 52. The first flange 90 located closest to the open end 86 of the conduit plug 54 includes the valve seat 63 that forms a fluid resistant seal when the plate 61 is biased against the first flange 90. The valve seat 63 can define a fluid passage through the primary check valve 52. An annular groove 65 can be recessed into a side of the first flange 90 in between the plug passageway 82 and the radial outer surface 94. When fluid enters the conduit plug bore 42 from the primary fluid cavity 46, the fluid passes through the primary check valve 52 along a fluid path between the primary fluid cavity 46 and the conduit plug bore 42 past the annular flange 57. As fluid pressure within the conduit plug bore 42 builds, hydraulic force an be exerted on the plate 61 against the force of the biasing member 59 with respect to the annular groove 65. The plate 61 can then move away from the plug passageway 82 permitting fluid to flow into the plug passageway 82 and the secondary fluid cavity 48. As pressure reduces, the biasing member 59 can return the plate 61 to a position against the valve seat 63 thereby preventing fluid flow from the primary fluid cavity 46 to the secondary fluid cavity 48.

The primary check valve 52 in this implementation can be referred to as a two-way valve such that it can controllably permit the bidirectional flow of fluid through the plate 61. In this implementation, a plurality of metered flow orifices 67 can be created that pass through the plate 61. The metered flow orifices 67 can be cut into the plate at a defined quantity and diameter the combination of which can be specified based on a desired rate of fluid flow through the plate 61 per unit volume while the plate 61 is biased against the valve seat 63 of the first flange 90. The orifices 67 can permit a controlled/defined state of fluid flow through the plate 61. It should also be appreciated that the primary check valve 52 and the secondary check valve 56 can optionally be implemented as one-way valves that selectively permit the flow of fluid in one direction. One-way check valves can be implemented in a variety of ways, such as by using a ball that is displacably seated against a valve seat with a biasing member, such as a spring. Sufficient fluid flow against the ball can displace the ball relative to the valve seat allowing fluid to pass through the fluid passage. The secondary check valve 56 can be implemented in a way that is the same or similar to the primary check valve 52.

The primary check valve 52 and the secondary check valve 56 shown in FIGS. 2-5 can regulate a two-way flow of fluid. In that implementation, fluid from the secondary fluid cavity 48 can flow to the piston bore 40 through the secondary check valve 56 and fluid can also flow between an outer surface 98 of the secondary piston 64 and a surface of the inner sleeve cavity 100 as well as between an outer surface 102 of the inner sleeve 66 and a surface of the primary cavity 104 to the primary fluid cavity 46. From the primary fluid cavity 46, the fluid can flow through the primary check valve 52 to the conduit plug 54 and return to the secondary fluid cavity 48. Alternatively, fluid can flow from the piston bore 40 to the secondary fluid cavity 48 through the primary check valve 56 via the metered flow orifices 67. And fluid can also flow from the conduit plug 54 to the primary fluid cavity 46 through the primary check valve 52 via the metered flow orifices 67. The two-way flow permitted by the piston check valve 56 and the recirculation check valve 52 can provide a dampening effect when the primary piston 62, the secondary piston 64, or both move(s) axially relative to the housing 38.

The primary fluid cavity 46 and the secondary fluid cavity 48 can, at least partially, be formed by boring linear passageways that are orthogonal to each other into the housing 38. The conduit plug bore 42 can be formed in the housing 38 by an annularlyshaped cutting tool that cuts an annularlyshaped recess into the housing 38. Or in another implementation, the primary fluid cavity 46, the secondary fluid cavity 48, and the conduit plug bore 42 can be formed in the housing 38 during a casting process that inherently creates a housing shape. The primary fluid cavity 46 can fluidly connect the piston bore 40 with the conduit plug bore 42. The primary check valve 52 can be positioned at one end of the primary fluid cavity 46 in between the primary fluid cavity 46 and the conduit plug 54 and can regulate the flow of fluid between the primary fluid cavity 46 in the primary portion and the conduit plug 54 in the secondary portion. The primary piston 62 includes an annular seal 96 that encircles an outer surface of the primary piston 62 to inhibit the flow of fluid from the piston bore 40 in between the outer surface of the primary piston 62 and the piston bore 40. However, fluid in the piston bore 40 may flow between an outer surface of the secondary piston 64 and a surface of the inner sleeve cavity 74 as well as between an outer surface of the inner sleeve 102 and a surface 104 of the primary cavity 68 to the primary fluid cavity 46. When fluid flows from the primary fluid cavity 46 to the conduit plug 54 through the primary check valve 52, it can pass through the open end 86 of the plug passageway 82 and out the aperture(s) 84 into the space between the first flange 90 and the second flange 92. The fluid can then flow to the secondary fluid cavity 48. The conduit plug 54 and the secondary fluid cavity 48 exist in a secondary portion that also communicates with a fluid source (not shown) supplying fluid to the secondary fluid cavity 48. The secondary fluid cavity 48 can receive fluid from the fluid source along with fluid from the primary fluid cavity 46 via the conduit plug 54 and (optionally) a pressure relief valve.

In the implementations shown in FIGS. 2-3, the primary fluid cavity 46 fluidly connects the piston bore 40 to the secondary fluid cavity 48 through a pressure check valve 110 in addition to the conduit plug 52. The pressure conduit 108 is in fluid communication with the piston bore 40 and the primary fluid cavity 46 such that the conduit 108 can receive fluid and if a sufficient pressure exists in the piston bore 40/primary fluid cavity 46, the pressure check valve 110 can open and release fluid into the secondary fluid conduit 48. After the pressure in the high-pressure section has reduced, the pressure check valve 110 can close and prevent the flow of fluid to the secondary fluid conduit 48. The implementations shown FIGS. 4-5 omit the pressure check valve and pressure relief bore.

It is to be understood that the foregoing is a description of one or more embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

As used in this specification and claims, the terms " e.g. ,"“for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open- ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.