Clutch balance dam with cooling flow valve

Abstract

A clutch assembly includes a shaft, a backplate secured to the shaft, a plurality of clutch plates, a hydraulic piston, and a balance dam. The hydraulic piston is sealed to the shaft and is axially slidable on the shaft to clamp the plurality of clutch plates closed against the backplate to close the clutch assembly. The balance dam is secured to the shaft and is axially disposed between the backplate and the hydraulic piston. The balance dam has a cooling flow orifice and a cooling flow valve for regulating a flow of cooling oil through the cooling flow orifice. In some example embodiments, the cooling flow valve is a reed valve having a displaceable steel plate that is secured to the balance dam and is preloaded against the balance dam to cover the cooling flow orifice.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Non-Provisional Application No. 16 / 952,676, filed November 19, 2020, the entire disclosure of which is incorporated by reference herein. TECHNICAL FIELD

[0003] The present disclosure relates generally to clutch balance dams, and more particularly to clutch balance dams with cooling flow valves. BACKGROUND

[0004] Hydraulically operated clutch pistons with check valves are known. One example is shown and described in U.S. Patent No. 6,705,447 to Gorman et al., entitled PISTON FOR HYDRAULICALLY-OPERATED CLUTCH, which is hereby incorporated by reference as if fully set forth herein. SUMMARY

[0005] Example embodiments broadly include a clutch assembly including a shaft, a backplate fixed to the shaft, a plurality of clutch plates, a hydraulic piston, and a balance dam. The hydraulic piston is sealed to the shaft and is axially slidable on the shaft to clamp the plurality of clutch plates closed against the backplate. The balance dam is fixed to the shaft and is axially disposed between the backplate and the hydraulic piston. The balance dam has a cooling flow orifice and a cooling flow valve for regulating cooling oil flow through the cooling flow orifice. In some example embodiments, the cooling flow valve is a reed valve having a displaceable steel plate fixed to the balance dam and preloaded against the balance dam to cover the cooling flow orifice.

[0006] In some example embodiments, the displaceable steel plate includes a bonding seal or a sealing coating on an end that covers the cooling flow orifice. In example embodiments, the displaceable steel plate is flat and the thickness of the bonding seal or the sealing coating provides the preloading of the displaceable steel plate against the balance dam. In some example embodiments, the displaceable steel plate is fixed to the balance dam by a rivet. In example embodiments, the rivet is offset in a circumferential direction from the cooling flow orifice.

[0007] In some example embodiments, the hydraulic piston and the balance dam are sealed together to form a first portion of the balance chamber. In an example embodiment, a cooling flow valve is preloaded against the balance dam by a force such that the cooling flow valve seals the cooling flow orifice when the fluid pressure in the balance chamber is approximately 0.3 bar. In some example embodiments, both the hydraulic piston and the balance dam are sealed to a shaft, and this shaft forms a second portion of the balance chamber. In some example embodiments, the shaft has radial channels for introducing fluid into the balance chamber. In an example embodiment, the shaft includes an axial channel hydraulically connected to the radial channels.

[0008] In some example embodiments, the cooling flow valve is arranged to prevent coolant flow from the balance chamber when the shaft is stationary, and to allow coolant flow from the balance chamber when the shaft rotates. In one example embodiment, as the shaft rotates, the cooling flow valve is displaced away from the balance dam by dynamic pressure in the balance chamber, thereby allowing coolant flow to leave the balance chamber. In another example embodiment, as the hydraulic piston moves toward the balance dam, the cooling flow valve is displaced away from the balance dam by hydraulic pressure in the balance chamber, thereby allowing coolant flow to leave the balance chamber.

[0009] In some example embodiments, the clutch assembly includes a clutch disc carrier axially disposed between a back plate and a counterbalance dam, fixed to the back plate, and including an orifice for allowing radially flowing cooling oil to cool a plurality of clutch discs. In some example embodiments, the clutch assembly includes a resilient element axially disposed between a hydraulic piston and a counterbalance dam, thereby forcing the hydraulic piston away from the counterbalance dam. In some example embodiments, the resilient element includes a plurality of helical springs. In some example embodiments, the plurality of helical springs are arranged around a circumference radially arranged outside the cooling flow orifice.

[0010] In some example embodiments, the clutch assembly has a sealing plate. The sealing plate and a hydraulic spring are sealed together to form a first portion of the pressure chamber. In another example embodiment, both the sealing plate and the hydraulic spring are sealed to a shaft, which forms a second portion of the pressure chamber. Attached Figure Description

[0011] Figure 1 A cross-sectional view of a clutch assembly according to an example aspect of this disclosure is illustrated.

[0012] Figure 2 The diagram illustrates the use of Figure 1 Front view of the balance dam of the clutch assembly.

[0013] Figure 3 The diagram shows Figure 2 The diagram is shown as a front view of a balance dam without a cooling flow valve. Detailed Implementation

[0014] Embodiments of this disclosure are described herein. It should be understood that similar reference numerals appearing in different views of the accompanying drawings identify the same or functionally similar structural elements. Furthermore, it should be understood that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The drawings are not necessarily to scale; some features may be enlarged or minimized to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the various embodiments in various ways. As will be understood by those skilled in the art, various features illustrated and described with reference to any of the accompanying drawings may be combined with features illustrated in one or more other drawings to produce embodiments not explicitly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications. However, for a particular application or implementation, various combinations and modifications of features consistent with the teachings of this disclosure may be desired.

[0015] The terminology used herein is for descriptive purposes only and is not intended to limit the scope of this disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Although any method, apparatus, or material similar to or equivalent to those described herein may be used in the practice or testing of this disclosure, the following example methods, apparatus, and materials will now be described.

[0016] Reference Figures 1 to 3 Please describe it as follows. Figure 1 A cross-sectional view of a clutch assembly 100 according to an exemplary aspect of this disclosure is illustrated. Figure 2 The diagram illustrates the use of Figure 1 Front view of the balance dam 102 of the clutch assembly. Figure 3 The diagram shows Figure 2 Rear view of the balancing dam.

[0017] The clutch assembly 100 includes a shaft 102, a backplate 104, clutch plates 106, a hydraulic piston 108, and a balance dam 110. The backplate is secured to the shaft by, for example, rivets 112. The hydraulic piston is sealed to the shaft by a seal 114 and is axially slidable on the shaft to clamp the plurality of clutch plates closed against the backplate. The balance dam is secured to the shaft by, for example, rivets 116 and is disposed axially between the backplate and the hydraulic piston. The balance dam includes a cooling flow orifice 118 and a cooling flow valve 120 for regulating the flow of cooling oil through the cooling flow orifice, as described below. The cooling flow valve is disposed on the side of the balance dam facing the backplate.

[0018] The cooling flow valve 120 is a reed valve having a displaceable steel plate that is secured to the balance dam and preloaded against the balance dam to cover the cooling flow orifice. The displaceable steel plate includes a bonding seal or seal coating 122 on the end that covers the cooling flow orifice. In the illustrated embodiment, the displaceable steel plate is flat and the thickness of the bonding seal or seal coating provides the preloading of the displaceable steel plate against the balance dam. That is, the steel plate is not formed prior to assembly to the balance dam, but once the plate is pressed tightly against the balance dam, the bonding seal or seal coating displaces the end of the steel plate away from the balance dam by the thickness of the bonding seal or seal coating to preload the steel plate against the balance dam. The displaceable steel plate is secured to the balance dam by, for example, rivets 124 installed in rivet holes 126. As can be seen in FIGS. 1 and 2, the rivets are offset from the cooling flow orifice in a circumferential direction 128. Figure 2 and Figure 3 As can be seen in FIGS. 1 and 2, the rivets are offset from the cooling flow orifice in a circumferential direction 128.

[0019] The hydraulic piston 108 and the balance dam 110 are sealed together at a bonding seal 130 to form a first portion of a balance chamber 132. The cooling flow valve is preloaded against the balance dam by a force that causes the cooling flow valve to seal the cooling flow orifice at a fluid pressure in the balance chamber of about 0.3 bar. In other words, the preloading force is about the same as the force from a pressure of about 0.3 bar acting on the area of the cooling flow orifice. Thus, for a 1 mm diameter orifice size, the preloading force of the cooling flow valve will be about:

[0020]

[0021] Hydraulic piston 108 and balance dam 110 are sealed to shaft 102 at rivet 116 and seal 114, respectively, and the shaft forms part of balance chamber 132. Shaft 102 includes radial passage 134 for introducing fluid into balance chamber and axial passage 136 hydraulically connected to radial passage and sealed by press-fit ball 138. Passage 136 connects to flow passage in housing (not shown) for introducing cooling flow into balance chamber to hydraulically balance piston 108 and provide cooling flow for clutch disc 106 as described in more detail below. By hydraulically balancing the piston, it is meant that both balance chamber 132 and pressure chamber 140, located on opposite sides of piston 108, are filled with oil, so that any dynamic pressure effects from rotation of piston, balance dam, shaft, etc., are compensated, thereby improving piston controllability during clutch engagement events.

[0022] The cooling flow valve is arranged to prevent coolant from flowing out of the balance chamber when the shaft is stationary, and to allow coolant flow (shown by arrow 142) from the balance chamber when the shaft rotates. That is, the cooling flow valve remains closed and fluid in the balance chamber is held in place as long as the pressure of the cooling flow from passage 134 is about 0.3 bar or less. However, once the shaft (and piston, balance chamber, etc.) rotates, dynamic pressure is added to the static pressure of the cooling flow, causing the pressure to increase above 0.3 bar and opening the valve to allow cooling flow to the clutch disc 106. In other words, the cooling flow valve is displaced away from the balance dam by the dynamic pressure in the balance chamber when the shaft rotates, thereby allowing cooling flow to leave the balance chamber.

[0023] Additionally, for example, during clutch engagement, when the hydraulic piston moves toward the balance dam, the cooling flow valve can be displaced away from the balance dam by the hydraulic pressure in the balance chamber, thereby allowing cooling flow to leave the balance chamber. That is, when the piston moves toward the clutch disc to close the clutch, the volume of the balance chamber decreases, thereby increasing the pressure of the oil in the balance chamber, and the resulting pressure increase exceeds the rated pressure of 0.3 bar to open the cooling flow valve. It should be noted that although the pressure of 0.3 bar is used as an example, other static pressures of the oil in the balance chamber 132 are possible, and similar results will be produced if the cooling flow valve is designed accordingly.

[0024] The clutch assembly 100 also includes a clutch disc carrier 144, which is axially disposed between a back plate and a balance dam and secured to the back plate by rivets 146. The carrier 144 includes an orifice 148 for allowing a radial flow of cooling oil, indicated by arrows 150 and 152, to cool the plurality of clutch discs.

[0025] The clutch assembly 100 includes a resilient element 154 axially disposed between a hydraulic piston and a balance dam, thereby forcing the hydraulic piston away from the balance dam. In the illustrated example embodiment, the resilient element 154 includes a helical spring 156 arranged around a circumference radially arranged outside a cooling flow orifice. Although a helical spring is shown, other resilient elements are possible. For example, element 154 may include a Bavarian washer or a rubber disc.

[0026] Clutch assembly 100 includes a sealing plate 158. The sealing plate and hydraulic spring 108 are sealed together at a seal 160 to form part of a pressure chamber 132. Increasing the hydraulic pressure in the pressure chamber causes a piston to move toward a clutch disc 106, thereby pressing a back plate 104 against the clutch disc to engage (or disengage) the clutch. Shaft 102 includes a passage (not shown) in fluid communication with the pressure chamber 132, which regulates the pressure in the pressure chamber. Both the sealing plate and the hydraulic piston are sealed to the shaft at seals 162 and 114, respectively, and the shaft forms part of the pressure chamber.

[0027] While exemplary embodiments have been described above, it is not intended that these embodiments describe all possible forms covered by the claims. The language used in the application is descriptive rather than restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure. As previously described, features of various embodiments may be combined to form other embodiments that may not be explicitly described or illustrated in this disclosure. Although various embodiments may have been described as providing an advantage or superiority over other embodiments or prior art implementations with respect to one or more desired characteristics, those skilled in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, merchantability, appearance, packaging, size, suitability, weight, manufacturability, ease of assembly, etc. Therefore, any embodiment described as being less desirable with respect to one or more characteristics than other embodiments or prior art implementations is not outside the scope of this disclosure and may be desirable for a particular application.

[0028] List of reference numerals

[0029] 100 Clutch Assembly

[0030] 102 shafts

[0031] 104 backplate

[0032] 106 clutch disc

[0033] 108 hydraulic piston

[0034] 110 Balance Dam

[0035] 112 Rivet (Backplate to Shaft)

[0036] 114 Seals (Shaft to Hydraulic Piston)

[0037] 116 Rivet (Balance Dam to Shaft)

[0038] 118 Cooling flow orifice

[0039] 120 Cooling Flow Valve

[0040] 122 Combination seal or sealing coating

[0041] 124 rivets (from flow valve to balance dam)

[0042] 126 rivet holes

[0043] 128 circumferential direction

[0044] 130 Combined Seal (Balance Dam to Hydraulic Piston)

[0045] 132 balance chamber

[0046] 134 radial channels

[0047] 136-axis channel

[0048] 138-point ball

[0049] 140 pressure chambers

[0050] 142 Cooling Flow Arrow

[0051] 144 Clutch Plate Bearing

[0052] 146 rivets (from load-bearing component to back plate)

[0053] 148-hole (load-bearing component)

[0054] 150 Cooling Flow Arrow

[0055] 152 Cooling Flow Arrow

[0056] 154 elastic element

[0057] 156 coil spring

[0058] 158 sealing plate

[0059] 160 Seal (Hydraulic Piston to Sealing Plate)

[0060] 162 Seal (Shaft to Sealing Plate)

Claims

1. A clutch assembly comprising: a shaft; a backplate fixed to the shaft; a plurality of clutch plates; a hydraulic piston sealed to the shaft and axially slidable thereon to clamp the plurality of clutch plates closed against the backplate to shut the clutch assembly; and a balance dam: the balance dam is fixed to the shaft; the balance dam is disposed axially between the backplate and the hydraulic piston; and the balance dam comprises: a cooling flow orifice; and a cooling flow valve for regulating the flow of cooling oil through the cooling flow orifice. The cooling flow valve is a reed valve comprising a displaceable steel plate fixed to the balance dam and preloaded against the balance dam to cover the cooling flow orifice. The displaceable steel plate comprises a bonding seal or a sealing coating on an end covering the cooling flow orifice.

2. The clutch assembly of claim 1, wherein, The displaceable steel plate is flat and the thickness of the bonding seal or the sealing coating provides the preloading of the displaceable steel plate against the balance dam.

3. The clutch assembly of claim 2, wherein, The displaceable steel plate is fixed to the balance dam by a rivet.

4. The clutch assembly of claim 3, wherein, The rivet is offset in a circumferential direction from the cooling flow orifice.

5. The clutch assembly of claim 2, wherein, The hydraulic piston and the balance dam are sealed together to form a first portion of a balance chamber.

6. The clutch assembly of claim 5, wherein, The cooling flow valve is preloaded against the balance dam by a force that causes the cooling flow valve to seal the cooling flow orifice at a fluid pressure of 0.3 bar in the balance chamber.

7. The clutch assembly of claim 1, wherein, Both the hydraulic piston and the balance dam are sealed to the shaft, and the shaft forms a second portion of the balance chamber.

8. The clutch assembly of claim 7, wherein, The shaft comprises a radial passage for introducing fluid into the balance chamber.

9. The clutch assembly of claim 7, wherein, The shaft comprises an axial passage hydraulically connected to the radial passage.

10. The clutch assembly of claim 9, wherein, 12. The clutch assembly of claim 7, wherein:

11. The clutch assembly of claim 10, wherein, the cooling flow valve is arranged to prevent outward flow of cooling oil from the balance chamber when the shaft is stationary; and the cooling flow valve is arranged to allow outward flow of cooling oil flow from the balance chamber when the shaft is rotating. Upon rotation of the shaft, the cooling flow valve is displaced away from the balance dam by a dynamic pressure in the balance chamber, thereby allowing a cooling flow to exit the balance chamber. Upon displacement of the hydraulic piston towards the balance dam, the cooling flow valve is displaced away from the balance dam by a hydraulic pressure in the balance chamber, thereby allowing a cooling flow to exit the balance chamber.

13. The clutch assembly of claim 12, wherein, 15. The clutch assembly of claim 1 further comprising a clutch plate carrier:

14. The clutch assembly of claim 12, wherein, the clutch plate carrier is disposed axially between the backplate and the balance dam; the clutch plate carrier is fixed to the backplate; and the clutch plate carrier comprises an orifice for allowing a radially flowing cooling oil flow to cool the plurality of clutch plates.

16. The clutch assembly of claim 1 further comprising a resilient element disposed axially between the hydraulic piston and the balance dam, thereby forcing the hydraulic piston away from the balance dam. The resilient element comprises a plurality of coil springs. ​ 17. The clutch assembly of claim 16, wherein, ​ 18. The clutch assembly of claim 17, wherein, The plurality of coil springs are arranged around a circumference radially disposed outside the cooling flow orifice.

19. The clutch assembly of claim 1 further comprising a seal plate, wherein, The seal plate and the hydraulic piston are sealed together to form a first portion of a pressure chamber.

20. The clutch assembly of claim 19, wherein, Both the seal plate and the hydraulic piston are sealed to the shaft, and the shaft forms a second portion of the pressure chamber.

Images