Parking Brake System

Patent metadata

Field	Value
Publication number	US-2018119816-A1
Application number	US-201715840743-A
Country	US
Kind code	A1
Filing date	Dec 13, 2017
Priority date	Jul 24, 2015
Publication date	May 3, 2018
Grant date	—

Abstract

A parking brake system for a motor vehicle transmission is provided. The parking, brake system includes a brake cylinder having a brake piston movable between braking and locking positions, a piston lock provided to lock the brake piston in the locking position, a piston valve configured to activate the brake cylinder using a fluid, and a locking valve configured to activate the piston lock using a fluid. The piston valve can be connected, in a fluid-conducting manner on the downstream side facing away from the brake cylinder, to a supply pressure system, and the locking valve, on the side facing away from and downstream of the piston lock, can be connected in a fluid-conducting manner to the supply pressure system, such that the locking valve is arranged downstream of and parallel to the piston valve relative to the supply pressure system.

First claim

What is claimed is:

1 . A parking brake system for a motor vehicle transmission, comprising:
a piston lock; a brake cylinder having a brake piston movable between a braking position and a locking position; a piston valve in fluid communication with a supply pressure system on a side of piston valve opposite a side in fluid communication with the brake cylinder, the piston valve being configured to control fluid flow from the supply pressure system to the brake cylinder move the brake piston between the braking and locking positions; and a locking valve in fluid communication with the supply pressure system on a side of locking valve opposite a side in fluid communication with piston lock, the locking valve being configured to control fluid flow from the supply pressure system to actuate the piston lock such that the piston lock locks the brake piston in the locking position, wherein the locking valve and the piston valve are arranged in parallel relative to the supply pressure system.

2 . The parking brake system as claimed in claim 1 , wherein
the piston valve is a directional valve having at least three valve connectors and at least two control positions, and the locking valve is a directional valve having at least three valve connectors and at least two control positions.

3 . The parking brake system as claimed in claim 2 , wherein
the piston valve and the locking valve each have at least one control pressure connector.

4 . The parking brake system as claimed in claim 1 , further comprising:
a shut-off valve arranged between the locking valve and the piston lock, wherein
the shut-off valve is configured to prevent flow from the piston lock) to the locking valve ( 4 ), and
the shut-off valve is configured to permit flow from the locking valve to the piston lock until a pressure between the locking valve and the shut-off valve is equal to or greater than a locking pressure threshold value.

5 . The parking brake system as claimed in claim 4 , further comprising:
a throttling valve arranged between the shut-off valve and the piston lock, wherein
the throttling valve is configured to throttle flow from a fluid line between the shut-off valve and the piston lock to a tank return line.

6 . The parking brake system as claimed in claim 1 , wherein
at least one of the at least one control connector of the piston valve is configured to be in fluid communication with at least one of the at least one control connector of the locking valve.

7 . The parking brake system as claimed in claim 1 , wherein
at least one of the at least one control connectors of at least one the locking valve and the piston valve is configured to be in fluid communication with a start-up pressure connector of a start-up element of the motor vehicle transmission.

8 . The parking brake system as claimed in claim 7 , wherein
at least one of the at least one control connectors of at least one of the locking valve and the piston valve is configured to be in fluid communication with at least one shifting pressure connector of at least one shifting device of the motor vehicle transmission.

9 . The parking brake system as claimed in claim 8 , wherein
the locking valve is configured to be loaded with a locking valve spring actuating force by a locking valve prestress spring to move the locking valve into a first control position, one of the at least one of the control connectors of the locking valve is one of the control connectors in fluid communication with a start-up pressure connector, the locking valve is configured to be loaded via the one of the at least one of the control connectors of the locking valve with a locking valve control pressure from the start-up pressure connector, such that a pressure actuating force resulting from the locking valve control pressure from the start-up pressure connector acts in the same direction as the locking valve spring actuating force, and the locking valve is configured to be loaded with a second locking valve control pressure via another one of the at least one of the control connectors of the locking valve in fluid communication with the shifting pressure connector, such that a pressure actuating force resulting from the second locking valve control pressure from the shifting pressure connector acts in the opposite direction to the locking valve spring actuating force.

10 . The parking brake system as claimed in claim 7 , wherein
the piston valve is configured to be loaded with a piston valve spring actuating force by a piston valve prestress spring to move the piston valve into a first piston valve control position.

11 . The parking brake system as claimed in claim 10 , wherein
one of the at least one of the control connectors of the piston valve is one of the control connectors in fluid communication with a start-up pressure connector, and the piston valve is configured to be loaded with a first piston valve control pressure via the one of the at least one of the control connectors of the piston valve from the start-up pressure connector, such that a pressure actuating force resulting from the first piston valve control pressure acts in the opposite direction to the piston valve spring actuating force.

12 . The parking brake system as claimed in claim 11 , wherein
the piston valve is configured to be loaded with a second piston valve control pressure via another one of the at least one of the control connectors of the piston valve in fluid communication with the shifting pressure connector, such that a pressure actuating force resulting from the second piston valve control pressure from the shifting pressure connector acts in the opposite direction to the piston valve spring actuating force.

13 . A motor vehicle automatic transmission, comprising:
a parking brake system having
a piston lock;
a brake cylinder having a brake piston movable between a braking position and a locking position;
a piston valve in fluid communication with a supply pressure system on a side of piston valve opposite a side in fluid communication with the brake cylinder, the piston valve being configured to control fluid flow from the supply pressure system to the brake cylinder move the brake piston between the braking and locking positions; and
a locking valve in fluid communication with the supply pressure system on a side of locking valve opposite a side in fluid communication with piston lock, the locking valve being configured to control fluid flow from the supply pressure system to actuate the piston lock such that the piston lock locks the brake piston in the locking position,
wherein the locking valve and the piston valve are arranged in parallel relative to the supply pressure system.

14 . A motor vehicle, comprising:
a transmission having a parking brake system, the parking brake system having
a piston lock;
a brake cylinder having a brake piston movable between a braking position and a locking position;
a piston valve in fluid communication with a supply pressure system on a side of piston valve opposite a side in fluid communication with the brake cylinder, the piston valve being configured to control fluid flow from the supply pressure system to the brake cylinder move the brake piston between the braking and locking positions; and
a locking valve in fluid communication with the supply pressure system on a side of locking valve opposite a side in fluid communication with piston lock, the locking valve being configured to control fluid flow from the supply pressure system to actuate the piston lock such that the piston lock locks the brake piston in the locking positi

Assignees

• Bayerische Motoren Werke Ag

Inventors

• Gollmer Roland
• Liebert Sebastian
• Hoppe Andreas

Classifications

• F16H2312/02

  Driving off · CPC title

• F16H63/48

  Signals to a parking brake {or parking lock; Control of parking locks or brakes being part of the transmission} · CPC title

• F16H61/0206

  Layout of electro-hydraulic control circuits, e.g. arrangement of valves · CPC title

• F16H63/3433

  Details of latch mechanisms, e.g. for keeping pawls out of engagement · CPC title

• F16H63/3483 Primary

  with hydraulic actuating means · CPC title