Switching-valve arrangement for a shifting system of an automatic transmission

• US 20060234826A1
• Filed: 04/05/2006
• Published: 10/19/2006
• Est. Priority Date: 04/07/2005
• Status: Active Grant

• Current Assignee: Getrag Ford Transmissions GmbH
• Original Assignee: Martin Leibbrandt Reinhard Moehlmann
• Inventors: Leibbrandt, Martin, Moehlmann, Reinhard
• Granted Patent: US 7,410,438 B2
• Time in Patent Office: Days
• US Class Current: 476/10
• CPC Class Codes: F16H 2061/0253 Details of electro hydraulic valves, e.g. lands, ports, spools or springs
• CPC Class Codes: F16H 2061/1204 for malfunction caused by simultaneous engagement of different ratios resulting in transmission lock state or tie-up condition
• CPC Class Codes: F16H 2061/1236 using fail priority valves
• CPC Class Codes: F16H 61/12 Detecting malfunction or potential malfunction, e.g. fail safe in control of hydrostatic gearing F16H61/4192; Circumventing or fixing failures
• CPC Class Codes: F16H 61/30 Hydraulic or pneumatic motors or related fluid control means therefor
• CPC Class Codes: F16H 61/688 with two inputs, e.g. selection of one of two torque-flow paths by clutches
• CPC Class Codes: F16H 63/3023 the final output mechanisms comprising elements moved by fluid pressure band brake actuating mechanisms F16H63/3003

Abstract

The invention relates to a switching-valve arrangement for a shifting system of an automatic transmission having a first actuator for engaging and releasing gears, at least a second actuator for engaging and releasing gears, a first activatable switching valve, a second activatable switching valve, a first signal element, and a second signal element. By means of the signal elements and switching valves the first and second actuators can be pressurized. In case of failure of one of the signal elements one of the actuators can always be pressurized and even in case of erroneous operation of the first and second signal elements only one of the actuators can be pressurized at the same time.

Claims

1. A switching-valve arrangement for a shifting system of an automatic transmission having

a first actuator for engaging and releasing gears,

at least a second actuator for engaging and releasing gears,

a first activatable switching valve,

a second activatable switching valve,

a first signal element, and

a second signal element, wherein

by means of the first activatable switching valve, in a first position, the first actuator can be set to a pressureless state and, in a second position, the first actuator can be subjected to pressure, a first switching force being provided by the first signal element for switching the valve from the first position into the second position and for retaining it in the second position, and

by means of the second activatable switching valve, in a first position, the second actuator can be set to a pressureless state and, in a second position, the second actuator can be subjected to pressure, a second switching force being provided by the second signal element for switching the valve from the first position into the second position and for retaining it in the second position, wherein

in case of failure of one of the signal elements one of the actuators can always be pressurized and even in case of erroneous operation of the first and second signal elements only one of the actuators can be pressurized at the same time.

2. The switching valve arrangement as claimed in claim 1, wherein the pressurizable actuator is provided for switching into at least one starting gear.

3. The switching valve arrangement of claim 1, wherein a coupling is provided between the first switching valve and the second switching valve, said coupling transmitting at least a part of the first switching force to the second switching valve, the resulting force acting on the second switching valve being insufficient to retain the second switching valve in its second position or to force it into its second position.

4. The switching-valve arrangement as claimed in claim 3, wherein the respective second position of the first and second switching valves is spring-loaded.

5. The switching-valve arrangement as claimed in claim 3, wherein the first switching force is greater than the second switching force, preferably approximately twice the magnitude.

6. The switching-valve arrangement as claimed in claim 3, wherein the coupling is mechanical.

7. The switching-valve arrangement as claimed in claim 3, wherein the coupling comprises a spring that, in a rest position, forces the switching valves into their respective first position.

8. The switching-valve arrangement as claimed in claim 3, wherein the coupling between the first and second switching valves prevents in a form-fitting manner that the first and second switching valves can simultaneously assume a second position.

9. The switching-valve arrangement as claimed in claim 3, wherein the first and the second signal elements are electromagnetic signal elements.

10. The switching-valve arrangement as claimed in claim 3, wherein the first and the second signal elements are pressure valves.

11. The switching-valve arrangement as claimed in claim 10, wherein the signal pressure of the signal element of the first switching valve equals the signal pressure of the signal element of the second switching valve.

12. The switching-valve arrangement as claimed in claim 10, wherein an effective surface area of a piston pressurized with the signal pressure of the first switching valve is greater than an effective surface area of a piston pressurized with the signal pressure of the second switching valve.

13. The switching-valve arrangement as claimed in claim 12, wherein the effective surface area of the piston of the first switching valve is approximately double the size of the effective surface area of the piston of the second switching valve.

14. The switching-valve arrangement as claimed in claim 1, wherein at least one of the switching valves is designed as a 3/2-way switching valve.