Piston, gear-change selector and gearshift

Patent metadata

Field	Value
Publication number	US-11905979-B2
Application number	US-202217813436-A
Country	US
Kind code	B2
Filing date	Jul 19, 2022
Priority date	Jul 19, 2021
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

A piston, in particular for a gear-change selector, including a piston body with a piston skirt and with a piston end face which can be pressurised with a working fluid. The piston includes a first sealing portion and a second sealing portion. The piston body and the first sealing portion have mutually complementary geometries so that they form a first vent channel. The first vent channel is arranged in a hydraulic series circuit with the second sealing portion. The second sealing portion prevents venting up to a first pressure and allows this above the first pressure. The invention furthermore concerns a gear-change selector and a gearshift for a vehicle.

First claim

The invention claimed is:

1. A piston for a gear-change selector, comprising:
a piston body with a piston skirt and with a piston end face which can be pressurised with a working fluid,
wherein the piston comprises a first sealing portion and a second sealing portion, wherein the piston body and the first sealing portion have mutually complementary geometries so that they form a first vent channel,
wherein the first vent channel is arranged in a hydraulic series circuit with the second sealing portion, and
wherein the second sealing portion is configured to prevent venting up to a first pressure and allows venting above the first pressure.

2. The piston according to claim 1 , wherein the piston end face has a depression in which a rubber-elastic sealing element is arranged, wherein the first sealing portion is part of the sealing element, wherein the piston body and the sealing element have mutually complementary geometries so that they form the first vent channel with a first free cross-sectional area, and in a pressure-relieved state, between mutually opposing surfaces of the depression and the first sealing portion, form a second vent channel with a second free cross-sectional area, wherein the first vent channel and the second vent channel are hydraulically connected in parallel, and furthermore wherein the depression and the sealing element are configured such that, as the temperature of the sealing element rises, its modulus of elasticity falls, and a pressurisation of the sealing element by the working fluid leads to a temperature- and pressure-dependent elastic deformation of the sealing element, and by means of the elastic deformation, to a reduction in the free cross-sectional area of the second vent channel.

3. The piston according to claim 2 , wherein the piston body and the sealing element are configured such that the temperature- and pressure-dependent elastic deformation of the sealing element reduces the free cross-sectional area of the second vent channel more greatly than the free cross-sectional area of the first vent channel.

4. The piston according to claim 2 , wherein the first vent channel and the second vent channel are arranged in a hydraulic series circuit with the second sealing portion, wherein the second sealing portion seals a vent opening in the piston body against the first and second vent channels up to a first pressure and opens this above the first pressure.

5. The piston according to claim 4 , wherein the depression has an outer region on the side of the piston end face, in which the rubber-elastic sealing element is arranged, and an inner region comprising the vent opening, wherein the second sealing portion in the form of a sealing lip is arranged between the inner region and the outer region.

6. The piston according to claim 4 , wherein the depression has a vent groove in its wall, which, together with the first sealing portion, forms the second vent channel, wherein the vent groove extends in the direction of the inner region from the piston end face to behind the outer region, and is configured and dimensioned such that the second vent channel is not closed by the sealing element at a first pressure and/or at a first temperature, and the temperature- and pressure-dependently elastically deformed sealing element increasingly closes the free cross-sectional area of the second vent channel as the pressure rises and/or the temperature rises, until the second vent channel is substantially completely closed above a second pressure and/or above a second temperature.

7. The piston according to claim 6 , wherein the vent groove has a height (h) which is smaller in the radial direction than a width (b) in the circumferential direction.

8. The piston according to claim 5 , wherein the depression has a vent notch in its wall, which, together with the first sealing portion, forms the first vent channel, wherein the vent notch extends in the direction of the inner region from the piston end face to behind the outer region, and is configured and dimensioned such that the vent notch is not closed by the sealing element even under a temperature- and pressure-dependent elastic deformation of the sealing element.

9. The piston according to claim 8 , wherein the vent notch has a height (h) which is greater in the radial direction than a width (b) in the circumferential direction.

10. The piston according to claim 2 , wherein the second vent channel has a smaller maximal distance from the sealing element than the first vent channel.

11. The piston according to claim 2 , wherein the depression is an end-face ring groove extending in the axial direction.

12. The piston according to claim 1 , wherein the piston has a piston seal, wherein the piston seal comprises a radial circumferential groove in the piston skirt, and wherein a self-sealing piston groove ring with a sealing lip is arranged in the circumferential groove.

13. The piston according to claim 1 , wherein the piston is a double-action piston.

14. A gear-change Gear change selector for a gearshift, wherein the gear-change selector comprises several pistons according to claim 1 , wherein the gear-change selector is a gear-change selector module which can be mounted on a transmission.

15. A gearshift comprising a gear-change selector according to claim 14 .

16. The piston according to claim 3 , wherein the first vent channel and the second vent channel are arranged in a hydraulic series circuit with the second sealing portion, wherein the second sealing portion seals a vent opening in the piston body against the first and second vent channels up to a first pressure and opens this above the first pressure.

17. The piston according to claim 5 , wherein the depression has a vent groove in its wall, which, together with the first sealing portion, forms the second vent channel, wherein the vent groove extends in the direction of the inner region from the piston end face to behind the outer region, and is configured and dimensioned such that the second vent channel is not closed by the sealing element at a first pressure and/or at a first temperature, and the temperature- and pressure-dependently elastically deformed sealing element increasingly closes the free cross-sectional area of the second vent channel as the pressure rises and/or the temperature rises, until the second vent channel is substantially completely closed above a second pressure and/or above a second temperature.

18. The piston according to claim 5 , wherein the depression has a vent notch in its wall, which, together with the first sealing portion, forms the first vent channel, wherein the vent notch extends in the direction of the inner region from the piston end face to behind the outer region, and is configured and dimensioned such that the vent notch is not closed by the sealing element even under a temperature- and pressure-dependent elastic deformation of the sealing element.

19. The piston according to claim 3 , wherein the second vent channel has a smaller maximal distance from the sealing element than the first vent channel.

20. The piston according to claim 3 , wherein the depression is an end-face ring groove extending in the axial direction.

Assignees

• Fte Automotive Gmbh

Inventors

• Schorn Andreas
• Berger Ralph
• Marks Paul
• Landgraf Alexander

Classifications

• F15B15/14 Primary

  of the straight-cylinder type · CPC title

• F16H61/30

  Hydraulic {or pneumatic} motors {or related fluid control means} therefor · CPC title

• F16H63/3023 Primary

  the final output mechanisms comprising elements moved by fluid pressure (band brake actuating mechanisms F16H63/3003) · CPC title

• F16H2061/004

  Venting trapped air from hydraulic systems · CPC title

• F16H2061/308

  Modular hydraulic shift units, i.e. preassembled actuator units for select and shift movements adapted for being mounted on transmission casing · CPC title