CN-121986227-A - Hydraulic piston design

Abstract

A system for engaging a clutch plate pack using a hydraulic piston has been developed. The system may be used with an automatic transmission or other portion of a vehicle's driveline. The system includes a piston, a clutch plate pack, and a housing containing the piston and the clutch plate pack. To engage and disengage the piston with the clutch plate pack, the system is configured to fill and empty the hydraulic chamber of the hydraulic side of the piston such that hydraulic fluid moves the piston toward and away from the clutch plate pack. The piston includes one or more shims or spacer columns that form a flow gap. The piston is also configured to position the seal on the piston closer to the hydraulic side.

Inventors

• Inout Manta
• EVAN MEREDITH

Assignees

• 艾里逊变速箱公司

Dates

Publication Date

20260505

Application Date

20240812

Priority Date

20230822

Claims (20)

1. 1.A system, comprising: A clutch assembly includes The clutch plate set is provided with a plurality of clutch plates, A housing defining a cylinder bore, A piston slidably disposed in the cylinder bore, Wherein the piston is configured to actuate the clutch plate pack, Wherein the piston has a head, and Wherein the head has one or more shims extending from the head.
2. 2. The system of claim 1, further comprising: A housing defining a flow passage leading to the cylinder bore; Wherein the flow passage is configured to deliver hydraulic fluid, and Wherein the head of the piston is configured to reduce a flow restriction of the hydraulic fluid from the flow passage.
3. 3. The system of claim 2, wherein the gasket defines one or more gaps in which the hydraulic fluid flows.
4. 4. A system according to claim 3, wherein: the head comprises an inner head and an outer head; The inner head being disposed radially inward relative to the outer head, and The shim is positioned on the inner head.
5. 5. The system of claim 2, wherein: the flow passage has an opening to the cylinder bore; the flow channel having a channel wall, and The gasket is aligned with the channel wall of the flow channel to reduce flow restriction of the hydraulic fluid.
6. 6. The system of claim 2, wherein: the piston having an engaged position at which the piston engages the clutch plate pack; The piston having a disengaged position in which the piston is disengaged from the clutch plate pack; The cylinder bore having a cylinder bore bottom wall, and The gasket is configured to contact the cylinder bore bottom wall when in the separated position.
7. 7. The system of claim 6, further comprising: a spring configured to bias the piston to the disengaged position.
8. 8. The system of claim 1, wherein: the clutch assembly has a clutch side and a hydraulic side positioned opposite the clutch side; The head defines a groove configured to receive a seal to seal the cylinder bore; The head being configured to recess the seal toward the hydraulic side, and The seal includes a gasket.
9. 9. The system of claim 1, wherein: The head comprises an inner head and an outer head, and The inner head is disposed radially inward relative to the outer head.
10. 10. The system of claim 9, further comprising: Wherein the inner head defines an inner groove; An inner gasket received within the inner groove; Wherein the inner gasket is configured to seal the cylinder bore; Wherein the outer head defines an outer groove; an outer gasket is received within the outer groove; Wherein the outer gasket is configured to seal the cylinder bore, and Wherein the head of the piston is configured to recess the inner and outer washers further into a cylinder bore.
11. 11. The system of claim 10, wherein: The head defining a channel, and The channel is defined between the inner head and the outer head.
12. 12. The system of claim 1, wherein: the piston having an engagement member extending opposite the head, and The engagement member is configured to engage the clutch plate set.
13. 13. The system of claim 12, wherein: the engagement member having an inner ridge and an outer ridge; the inner ridge being positioned radially inward relative to the outer ridge, and The engagement member defines a cavity between the inner ridge and the outer ridge.
14. 14. The system of claim 1, wherein: the housing defining a flow passage leading to the cylinder bore; the piston having an engaged position at which the piston engages the clutch plate pack; The piston having a disengaged position in which the piston is disengaged from the clutch plate pack; the head comprises an inner head and an outer head; the inner head is disposed radially inward relative to the outer head; The head defines a channel; the channel is defined between the inner head and the outer head; the shims define one or more gaps in which the hydraulic fluid flows; the cylinder bore having a bore bottom wall; The gasket being configured to contact the cylinder bore bottom wall when in the separated position; The flow passage is configured to supply hydraulic fluid to and discharge hydraulic fluid from the cylinder bore; the cylinder bore bottom wall facing the head of the piston; The spacer extending from the inner head to form a spacer post; the inner head portion and the outer head portion each have a surface facing the cylinder bore bottom wall, the surfaces being flush with each other, and The gasket extends from the surface of the inner head portion farther toward the cylinder hole bottom wall than the surface of the outer head portion.
15. 15. The system of claim 14, wherein: The channel having a floor and walls extending from opposite sides of the floor; the walls of the channels along shims at the inner head are aligned with the channel walls of the flow channels; the cylinder bore bottom wall defining an opening of the flow passage to the cylinder bore, and The flow passage has a passage wall at an opening in the cylinder bore bottom wall.
16. 16. A system, comprising: A clutch assembly includes A housing defining a cylinder bore; the clutch plate set is provided with a plurality of clutch plates, A piston configured to actuate the clutch plate set, wherein the piston has a head, wherein the head comprises an inner head and an outer head, wherein the piston has an engaged position at which the piston engages the clutch plate set, wherein the piston has a disengaged position at which the piston is disengaged from the clutch plate set; a spring configured to bias the piston to the disengaged position; Wherein the head of the piston is configured to recess the inner and outer washers further into the cylinder bore; Wherein the inner head defines an inner groove; An inner washer is received in the inner groove; Wherein the inner gasket is configured to seal the cylinder bore; Wherein the outer head defines an outer groove; an outer washer is received in the outer groove, and Wherein the outer gasket is configured to seal the cylinder bore.
17. 17. The system of claim 16, wherein the head defines a channel defined between the inner head and the outer head.
18. 18. The system of claim 17, wherein: The channel has a bottom plate, and The inner and outer washers have surfaces that are aligned with the floor of the channel in a planar manner.
19. 19. The system of claim 16, wherein: the housing defining a flow passage leading to the cylinder bore; The flow passage configured to deliver hydraulic fluid, and The head of the piston is configured to reduce a flow restriction of the hydraulic fluid from the flow passage.
20. 20. The system of claim 19, wherein: The head having one or more shims extending from the head, and The shims define one or more gaps in which the hydraulic fluid flows.

Description

Hydraulic piston design Background Hydraulic pistons are used in a variety of applications. For example, hydraulic pistons are commonly used to actuate clutch plates in a transmission of a vehicle. Hydraulic pistons in a transmission need to engage and disengage clutch plates in a consistent and timely manner. Otherwise, poor performance or even damage may result. Accordingly, improvements are needed in this field. Disclosure of Invention A unique hydraulic piston design has been developed that actuates the clutch plates in a quick and consistent manner and addresses other issues. During the transition between the engaged and disengaged states of the clutch plates in the clutch plate pack, some piston designs have been found to operate unevenly and/or slowly. For example, to simplify the sealing of the piston, a newer or intermediate piston design has been developed. During development, such intermediate piston designs were found to engage and disengage the clutch plate pack too slowly and/or in an unreliable manner compared to the old designs. Inconsistent and slow operation of the pistons can affect the performance quality of the vehicle, for example, often resulting in poor gear shifting performance and/or poor clutch performance. After analyzing the performance between the earlier and intermediate piston designs, it was unexpectedly found that the oil return performance of the hydraulic fluid (e.g., oil) in the newer intermediate design was worse than in the older piston design. To actuate or push the piston to engage clutch plates of a clutch plate pack, pressurized hydraulic fluid is supplied to the piston within a cylinder bore of a transmission (or other device) through one or more hydraulic fluid passages. Typically, but not always, the piston is biased by one or more return springs to disengage from the clutch plate pack. Pressurized hydraulic fluid is required to overcome such spring force to compress and clamp the piston against the clutch pack in this engaged or applied position. To disengage the piston from the clutch plate pack, hydraulic fluid is discharged through the same hydraulic fluid passage that supplies hydraulic fluid, and a return spring pushes the piston back into the piston cylinder bore, into a disengaged state, or to a disengaged position (i.e., an installed position). In studying the intermediate piston design, it was found that the piston exhibited a generally flat surface or area at the opening of the hydraulic fluid passage. Essentially, the piston mainly covers the opening to restrict the flow of hydraulic fluid in the cylinder bore when being introduced and discharged. In other words, the intermediate piston design was found to reduce the effective area or volume of the cylinder bore. A housing or drum hub of the clutch assembly in the transmission defines a cylinder bore in which a piston is slidably disposed. In one form, the piston is annular and the cylinder bore is likewise annular. To enhance the flow of hydraulic fluid within the cylinder bore of the piston, the piston includes one or more shims or spacer columns that form one or more flow gaps along the head of the piston. The gasket separates the piston head from the closed end of the cylinder bore where the opening of the hydraulic fluid passage supplies hydraulic fluid to the cylinder bore. During piston contraction, hydraulic fluid can flow in the flow gap between the shims. When the piston is in the disengaged or installed position, any hydraulic fluid in the cylinder bore is at a relatively lower pressure than when the piston is in the engaged or applied position. When the piston is disengaged from the clutch pack, the return spring compresses the piston's shim against the surface of the closed end of the piston cylinder bore. The flow gap between the shims allows the hydraulic fluid to flow freely back into the hydraulic fluid passage. In one form, the gasket is positioned to generally prevent blocking the opening of the hydraulic fluid passage. The shims are generally aligned with the corresponding walls of the hydraulic fluid passages. By positioning the shims in this manner, hydraulic fluid can flow into and out of the piston cylinder bores in an unobstructed manner to promote a generally laminar flow of hydraulic fluid. In one version, the shims and corresponding flow gaps are located radially inward of the piston head. It should be appreciated that this configuration of the piston promotes free flow of hydraulic fluid, which in turn promotes rapid and consistent actuation of the clutch pack, regardless of temperature or other environmental conditions. The piston also includes an inner sealing ring or gasket and an outer sealing ring or gasket that slidingly seals against the wall of the cylinder bore. The seals are designed to reduce hydraulic leakage around the piston when the hydraulic fluid is pressurized. The piston is configured such that the sealing ring is recessed as far as possible within the