WO2019168543A1

WO2019168543A1 - Hydraulic chain tensioner with band check valve

Info

Publication number: WO2019168543A1
Application number: PCT/US2018/020630
Authority: WO
Inventors: Toru Shinoyama
Original assignee: Borgwarner Inc.
Priority date: 2018-03-02
Filing date: 2018-03-02
Publication date: 2019-09-06

Abstract

A hydraulic chain tensioner assembly including an inner sleeve, configured to be received within a piston cavity formed in a piston that slides relative to a piston bore in a housing of a hydraulic chain tensioner to engage a chain, wherein the inner sleeve comprises an inner sleeve diameter and an outer sleeve diameter; an inner sleeve cavity defined by the inner sleeve diameter; a valve section located at one end of the inner sleeve having one or more fluid openings configured to communicate fluid between the inner sleeve cavity and the piston cavity; and a check valve comprising a band valve member releasably covering the fluid opening(s) such that the band valve member selectively permits fluid flow through the fluid opening(s).

Description

HYDRAULIC CHAIN TENSIONER WITH BAND CHECK VALVE

TECHNICAL FIELD

The present application relates to hydraulic chain tensioners and, more particularly, hydraulic chain tensioners with check valves.

BACKGROUND

Internal combustion engines (ICEs) use endless loops such as a chain or a belt to communicate rotational energy from a crankshaft to one or more camshafts and precisely control the angular position of the camshafts relative to the crankshaft. ICEs using chains that loop around a crankshaft sprocket and one or more camshaft sprockets can be maintained at a proper tension using a hydraulic chain tensioner. Hydraulic chain tensioners use a piston that engages the timing chain to apply a certain amount of force to create an optimum amount of tension on the chain. However, the amount of force needed to create an optimum amount of tension on the chain varies depending on a variety of factors. For instance, variables such as temperature, engine speed, and the age of the chain each can lay a role that affects how much force should be ap lied to the chain

Apart from regulating the amount of force applied to the chain, hydraulic chain tensioners may also have side effects of tensioner operation. For example, the hydraulic chain tensioner may generate noise, vibration, and harshness (NVH). For example, when the ICE is operational, a fluid supply can deliver pressurized engine oil to a piston of the hydraulic chain tensioner. However, when the ICE is turned off pressurized engine oil may leak out of the hydraulic chain tensioner leaving a pocket of air next to the piston where the engine oil once existed. Then, when the ICE begins operating again, the pocket of air may not provide as effective reduction in NVH when compared to the engine oil the air replaced. It would be helpful to prevent the leakage of fluid from the hydraulic chain tensioner yet still efficiently regulate fluid flow to the piston. SUMMARY

In one implementation, a hydraulic chain tensioner assembly includes an inner sleeve configured to be received within a piston cavity formed in a piston that slides relative to a piston bore in a housing of a hydraulic chain tensioner to engage a chain, wherein the inner sleeve comprises an inner sleeve diameter and an outer sleeve diameter; an inner sleeve cavity defined by the inner sleeve diameter; a valve section located at one end of the inner sleeve having one or more fluid openings configured to communicate fluid between the inner sleeve cavity and the piston cavity; and a check valve comprising a band valve member releasably covering the fluid opening(s) such that the band valve member selectively permits fluid flow through the fluid opening(s).

In another implementation, a hydraulic chain tensioner assembly includes an inner sleeve, configured to be received within a piston cavity formed in a piston that slides relative to a piston bore in a housing of a hydraulic chain tensioner to engage a chain, wherein the inner sleeve comprises an inner sleeve diameter and an outer sleeve diameter; an inner sleeve cavity defined by the inner sleeve diameter; a valve section of the inner sleeve located at one end of the inner sleeve includes an inner surface having a smaller diameter than the inner sleeve diameter and an outer surface having a smaller diameter than the outer sleeve diameter wherein the valve section includes one or more fluid openings that are configured to communicate fluid between the inner surface and the outer surface; and a check valve comprising a band valve member that is annularly shaped to cover the fluid opening(s) such that the band valve member releasably contacts an upper annular valve seat and a lower annular valve seat that are axially-spaced and located on the outer surface of the valve section, wherein the band valve member selectively permits fluid flow through the fluid opening(s).

In yet another implementation, a hydraulic chain tensioner assembly includes a housing having a piston bore and one or more fluid passages communicating fluid from a fluid source; a piston, received within the piston bore, having a closed end and an open end collectively defining a piston cavity; an inner sleeve, having an inner sleeve cavity, located concentrically and radially inward relative to the piston including one or more fluid openings that communicate fluid from the inner sleeve cavity to the piston cavity; and a check valve including a band valve member positioned to selectively permit fluid flow through one or more fluid openings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a cross-sectional view depicting an implementation of a hydraulic chain tensioner assembly;

Figure 2 is a cross-sectional view depicting a portion of an implementation of a hydraulic chain tensioner assembly;

Figure 3 is another cross-sectional view depicting a portion of an implementation of a hydraulic chain tensioner assembly;

Figure 4 is a perspective view depicting a cross-sectional portion of an implementation of a hydraulic chain tensioner assembly; and

Figure 5 is a plan view depicting a cross-sectional portion of an implementation of a hydraulic chain tensioner assembly.

DETAILED DESCRIPTION

A hydraulic chain tensioner assembly includes a piston that slides along an axis within a piston bore relative to a tensioner housing to engage and add tension to a timing chain on an internal combustion engine (ICE) in response to the application of fluidic pressure. The piston is open on one end and closed on another end forming a piston cavity. The closed end can be oriented so that it is closer to the ground relative to the open end so that the piston cavity can act as a fluid reservoir holding fluid within the cavity. The piston cavity can receive an inner sleeve that regulates the flow of fluid between a low-pressure portion and a high-pressure portion of the hydraulic chain tensioner. The inner sleeve can include an open end and a closed end; the closed end can have one or more fluid openings or apertures that selectively permit fluid to pass between the low- pressure portion and the high-pressure portion through a check valve. The check valve uses a band valve member to regulate the flow of fluid between the inner sleeve (low-pressure portion) and the piston cavity (high-pressure portion). In one implementation, the inner sleeve can include a valve portion having an inner diameter and an outer diameter that is reduced relative to an inner sleeve diameter and an outer sleeve diameter, respectively. One or more fluid openings communicate fluid between the inner sleeve and the piston cavity. One or more band valve members can releasably cover the opening(s) to selectively permit fluid to flow through the fluid openings. The valve portion can be annularly shaped such that the band valve member is also annularly-shaped and can slide axially over an outer surface of the valve portion to control flow through the fluid opening(s). The piston cavity can extend substantially the entire length of the piston bore when the piston is fully retracted within the piston bore. The piston cavity can fill with fluid such as engine oil, and maintain a high level of fluid even after ICE shutdown.

As the piston slides toward the chain along an axis concentric with the bore and away from the housing, fluid from the low-pressure portion can flow past the band valve member(s) of the check valve through the fluid opening(s) into the high-pressure portion of the tensioner. The band valve member(s) can also prevent fluid flow from the high-pressure portion to the low-pressure portion. In response to force exerted on the piston toward the housing, the band valve member(s) can prevent fluid from flowing into the low-pressure portion from the high-pressure portion. The band valve member(s) can conform to and abut the outer surface of the inner sleeve to form a fluid-tight seal that prevents fluid from flowing past the band valve member(s) from the piston cavity into the inner sleeve cavity. The band valve member can be shaped as a flat plane on which a straight line drawn between two points on that plane would wholly lie. Or the band valve member shape could be a curved plane that conforms to the outer surface of the valve portion. The band valve member shaped as a curved plane could be formed in the shape of an annular sleeve that slides over an outside surface of the valve portion/inner sleeve so that the annular sleeve closely conforms to the outside surface. In the past, hydraulic chain tensioners have used ball valves to regulate flow between low-pressure and high-pressure portions of hydraulic chain tensioners. However, ball valve assemblies include a plurality of parts and it would be helpful to reduce the quality of those parts. For example, a ball valve can include a separate ball valve spring that biases a ball against a valve seat closing the valve. In contrast, a check valve using the band valve member lacks such a spring and can decrease the quantity of elements in the check valve. In addition, the flow rate of fluid from the low-pressure portion to the high-pressure portion of a hydraulic chain tensioner is greater through check valves using band valve members than through check valves using ball valves, which increases check valve efficiency.

Turning to Figures 1-3 an implementation of a hydraulic chain tensioner assembly 10 is shown. The tensioner 10 includes a housing 12 in which a piston bore 14 is formed for receiving a piston 16. The housing 12 also includes a fluid pathway 18 that communicates fluid from a fluid suppl (not shown) to the piston bore 14. The piston 16 can be defined by an outer piston diameter 20 and an inner piston diameter 22. At one end, the piston includes a closed end 24 and, at an end distal to the closed end 24, the piston is open 26 forming a piston cavity 28. When installed on an internal combustion engine (ICE), the closed end 24 of the piston 16 is located below the open end 26 of the piston 16 such that the piston cavity 28 can form a fluid reservoir for the tensioner 10 and the opening of the piston bore 14 is facing downward. The outer piston diameter 20 is sized so that an outer surface of the piston 16 closely conforms to a surface of the piston bore 14 and prevents the escape of fluid from the piston cavity 28 and/or fluid supply between the piston 16 and the piston bore 14 into the atmosphere.

The tensioner assembly 10 in this implementation includes a ratcheting feature 30 that permits extension of the piston 16 away from the housing 12 but prevents compression of the piston 16 into the housing 12 in response to force from a timing chain (not shown). The outside surface of the piston 16 can include a plurality of annular grooves 32 that encircle the outside surface. A ratchet clip 34 can slide over the outside surface of the piston 16 and fit into one of the annular grooves 32. The ratchet clip 34 can be annular ly shaped to conform to the shape of the annular grooves 32 and when the ratchet clip 34 engages one of the annular grooves 32, the ratchet clip 34 resist axial movement relative to the piston 16. However, the ratchet clip 34 can he expanded radially outwardly from a groove to slide axially with respect to the piston 16 and engage a different annular groove. A ratchet recess 36 formed in the piston bore 14 can facilitate axial movement of the ratchet clip 34. The ratchet recess 36 can be formed as an elongated groove in the surface of the piston bore 14 that includes a ratchet recess diameter 38 that is larger than the piston bore 14. An extension shoulder 40 and a recess shoulder 42 can each engage the ratchet clip 34 and permit/restrict axial movement of the piston 16. As the piston 16 moves away from the housing 12 sliding axially relative to the piston bore 14 along axis (x) and toward the timing chain the extension shoulder 40 forces the ratchet clip 34 to expand radially outwardly out of engagement with an annular groove 32 and moves the ratchet clip 34 axially with respect to the outer surface of the piston 16 so that the ratchet clip 34 engages a different annular groove 32. In response to force against the piston 16 directing the piston 16 toward the housing 12, the ratchet clip 34 engages the recess shoulder 42 which compresses the clip 34 radially inwardly toward the piston surface and into one of the grooves 32 preventing the movement of the piston 16 inwardly along axis (x) toward the housing 12.

The piston cavity 28 receives a biasing element 44 and an inner sleeve 46. The inner sleeve 46 has an inner sleeve diameter 48 and an outer sleeve diameter 50 such that the inner sleeve diameter 48 defines an inner sleeve cavity 52. A valve portion 54 of the inner sleeve 46 includes one or more fluid openings 56 that define a fluid pathway between the inner sleeve cavity 32 and the piston bore 14. In some implementations, the valve portion 54 can have an inner surface 58 and an outer surface 60 having diameter values that are smaller than the inner sleeve diameter 48 and the outer sleeve diameter 50, respectively. The valve portion 54 can include a check valve 62 using a band valve member 64 that regulates the flow of fluid through the fluid openings 56. In this implementation the band valve member 64 is an annularlyshaped band that slides over an outer surface 60 of the valve portion 54. The annularly^¬ shaped band can include an upper valve surface 66 and a lower valve surface 68 that engage the outer surface 60 of the valve portion 54 at an upper valve seat 70 and a lower valve seat 72, respectively. A check valve retainer 74 can fix the band valve member 64 relative to the outer surface 60 of the valve portion 54. The check valve retainer 74 can press radially inwardly against the band valve member 64 at an axial location along the valve portion 54 that is concentric with the lower valve surface 68. The valve portion 54 in this implementation includes four fluid openings 56 that communicate fluid between the inner sleeve cavity 52 and the piston cavity 28. In some implementations, the outer surface 60 of the valve portion 54 can also include an engagement feature, in addition or instead of the check valve retainer 74, that prevents axial and/or rotational movement of the band valve member 64 relative to the surface 60. This will be discussed in more detail below. The biasing element 44, such as a coil spring, is placed in the piston cavity 28 such that it abuts the closed end 24 of the piston 16. The inner sleeve 46 can be inserted into the piston cavity 28 and a combined assembly including the piston 16, the biasing element 44, and the inner sleeve 46 may be slid into the piston bore 14 of the hydraulic chain tensioner assembly 10.

Figures 2-3 depict the valve portion 54 of the inner sleeve 46 in more detail. Figure 2 shows the check valve 62 in a forward flow condition in which fluid is flowing from the inner sleeve cavity 52 to the piston cavity 28 through the fluid openings 56 and past the band valve member 64. Fluid can flow through the fluid openings 56 from the inner sleeve cavity 52 to the piston cavity 28 in between the upper valve surface 66 and upper valve seat 70. Fluid can also flow from the inner sleeve cavity 52 to the piston cavity 28 in between the lower valve surface 68 and the lower valve seat 72. Figure 3 show's the check valve 62 in a closed condition. The band valve member 64 seals the fluid openings 56 at both the upper valve seat 70 and the lower valve seat 72 preventing fluid flow from the piston cavity 28 to the inner sleeve cavity 52.

n

l Figures 4-5 depict cross-sections of another implementation of a valve portion 54 of an inner sleeve 46 having a band valve member 64’ fit over the outer surface 60’ of the valve portion 54 In the implementation shown in Figures 4-5, the outer surface 60’ of the valve portion 54 includes an engagement feature 76 that mechanically links with the band valve member 64' to prevent axial and/or rotational movement of the band valve member 64' relative to the valve portion 54. The outer surface 60' of the valve portions 54 can include a radially-outwardly extending protuberance 78 and the band valve member 64' can include a corresponding engagement slot 80 that is shaped to receive the protuberance 78 through the slot 80 The slot 80 can engage the protuberance 78 and prevent the band valve member 64' from axial or rotational movement relative to the valve portion 54 and inner sleeve 46.

The rate of fluid flow from the inner sleeve cavity to the piston cavity through the fluid openings at different pressures has been measured and compared to fluid flow rates of past hydraulic chain tensioners. For example, Table 1 below depicts results of testing involving hydraulic chain tensioners and, more particularly, the rate of fluid flow through a check valve in a tensioner using a band valve member relative to fluid flow through a check valve in a tensioner using a bail valve. At all fluid pressure level values, a check valve using the band valve member provided a higher flow rate of fluid relative to a check valve using the ball valve.

Table 1

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 d iffer e nt interp re tation

Claims

What is claimed is:

1. A hydraulic chain tensioner assembly comprising:

an inner sleeve, configured to be received within a piston cavity formed in a piston that slides relative to a piston bore in a housing of a hydraulic chain tensioner to engage a chain, wherein the inner sleeve comprises an inner sleeve diameter and an outer sleeve diameter;

an inner sleeve cavity defined by the inner sleeve diameter;

a valve section located at one end of the inner sleeve having one or more fluid openings configured to communicate fluid between the inner sleeve cavity and the piston cavity; and

a check valve comprising a band valve member releasably covering the fluid opening(s) such that the band valve member selectively permits fluid flow through the fluid opening(s).

2. The hydraulic chain tensioner assembly recited in claim 1, wherein the piston includes a closed end and an open end, whereby the closed end faces downward creating a fluid reservoir in the piston cavity.

3. The hydraulic chain tensioner assembly recited in claim 1, wherein the inner sleeve includes an open end, and a closed end comprising a plurality of fluid openings that communicate fluid between the inner sleeve cavity and the piston cavity through the check valve

4. The hydraulic chain tensioner assembly recited in claim 1, wherein the band valve member is annularly shaped and closely conforms to an annularlyshaped outer surface of the valve section.

5. The hydraulic chain tensioner assembly recited in claim 1, further comprising an engagement feature carried at least partially by an outer surface of the valve section that prevents the axial or rotational movement of the valve member.

6. The hydraulic chain tensioner assembly recited in claim 1, further comprising a check valve retainer that secures a portion of the valve member to an outer surface of the valve section.

7. A hydraulic chain tensioner assembly, comprising:

an inner sleeve cavity defined by the inner sleeve diameter;

a valve section of the inner sleeve located at one end of the inner sleeve includes an inner surface having a smaller diameter than the inner sleeve diameter and an outer surface having a smaller diameter than the outer sleeve diameter, wherein the valve section includes that one or more fluid openings are configured to communicate fluid between the inner surface and the outer surface; and

a check valve comprising a band valve member that is annularly shaped to cover the fluid opening(s) such that the band valve member re!easably contacts an upper annular valve seat and a lower annular valve seat that are axially- spaced and located on the outer surface of the valve section, wherein the band valve member selectively permits fluid flow through the fluid opening(s).

8. The hydraulic chain tensioner assembly recited in claim 7, wdierein the piston includes a closed end and an open end, whereby the closed end faces downward creating a fluid reservoir in the piston cavity.

9. The hydraulic chain tensioner assembly recited in claim 7, wherein the band valve member is annularly shaped and closely conforms to an annularlyshaped outer surface of the valve section.

10. The hydraulic chain tensioner assembly recited in claim 7, further comprising an engagement feature carried at least partially by the outer surface of the valve section that prevents the axial or rotational movement of the valve member.

11. The hydraulic chain tensioner assembly recited in claim 7, further comprising a check valve retainer that secures a portion of the valve member to an outer surface of the valve section.

12. A hydraulic chain tensioner assembly, comprising:

a housing that includes a piston bore and one or more fluid passages communicating fluid from a fluid source!

a piston, received within the piston bore, having a closed end and an open end collectively defining a piston cavity!

an inner sleeve, having an inner sleeve cavity, located concentrically and radially inward relative to the piston including one or more fluid openings that communicate fluid from the inner sleeve cavity to the piston cavity ! and

a check valve including a band valve member positioned to selectively permit fluid flow through one or more fluid openings.

13. The hydraulic chain tensioner assembly recited in claim 12, wherein the piston includes a closed end and an open end, whereby the closed end faces downward creating a fluid reservoir in the piston cavity.

14. The hydraulic chain tensioner assembly⁷ recited in claim 12, wherein the band valve member is annuiar!y shaped and closely conforms to an annularlyshaped outer surface of the valve section.

15. The hydraulic chain tensioner assembly recited in claim 12, further comprising an engagement feature at least partially carried by⁷ the outer surface of the valve section that prevents the axial or rotational movement of the valve member.

16. The hydraulic chain tensioner assembly recited in claim 12, further comprising a check valve retainer that secures a portion of the valve member to an outer surface of the valve section.