Transmission Park Control System

• US 20190120376A1
• Filed: 10/20/2017
• Published: 04/25/2019
• Est. Priority Date: 10/20/2017
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Gittins, Scott Joseph, Malnar, Matthew Scott, Lynch, Allison, Waldock, Lisa, McDonnell, Alexander Phillip
• Granted Patent: US 10,344,858 B2
• Time in Patent Office: Days
• CPC Class Codes: F16H 2061/0253 Details of electro hydraulic valves, e.g. lands, ports, spools or springs
• CPC Class Codes: F16H 2200/0069 the gear ratios comprising ten forward speeds
• CPC Class Codes: F16H 2200/2012 with four sets of orbital gears
• CPC Class Codes: F16H 2200/2046 with six engaging means
• CPC Class Codes: F16H 3/66 composed of a number of gear trains without drive passing from one train to another
• CPC Class Codes: F16H 61/0031 using auxiliary pumps, e.g. pump driven by a different power source than the engine
• CPC Class Codes: F16H 63/3425 characterised by pawls or wheels
• CPC Class Codes: F16H 63/3483 with hydraulic actuating means
• CPC Class Codes: F16H 63/48 Signals to a parking brake or parking lock; Control of parking locks or brakes being part of the transmission
• CPC Class Codes: F16K 11/0704 comprising locking elements
• CPC Class Codes: F16K 15/00 Check valves valves specially adapted for inflatable balls A63B41/00
• CPC Class Codes: F16K 31/1221 one side of the piston being spring-loaded

Abstract

A park valve includes a slidable end-cap. Under normal circumstances, the end-cap is held in a nominal position by a spring, such as a Belleville spring. The park valve performs a multi-plexing function in which an out-of-park circuit is connected to line pressure when the valve is in an out-of-park position and is vented when the valve is in a park position. In an intermediate position, a hydraulic lock condition may potentially occur. When engaging park, the hydraulic lock condition is prevented by the slidable end-cap.

Claims

1. A valve comprising:

a bore;

a spool slidably supported within the bore; and

an end-cap held in a neutral position with respect to the bore by a spring, wherein the end-cap, spool, and bore define a first chamber and the spring deforms in response to fluid pressure in the first chamber such that the end-cap slides with respect to the bore from the neutral position.

2. The valve of claim 1 wherein the end-cap, spool, and bore define a second chamber and the spring deforms in response to fluid pressure in the second chamber such that the end-cap slides with respect to the bore from the neutral position.

3. The valve of claim 1 wherein

the spool and the bore define a third chamber that is selectively fluidly connected to the first chamber via a check valve;

the bore defines a first port fluidly connecting the third chamber to a pressure source whenever the spool is in a first position;

the bore defines a second port venting the third chamber whenever the spool is in a second position; and

the first and second ports are both closed when the spool is in an intermediate position between the first and second positions.

4. The valve of claim 3 wherein the sliding of the end-cap with respect to the bore permits the spool to move from the intermediate position toward the first position without changing a volume of the first chamber thereby opening the second port.

5. The valve of claim 4 wherein the spool and the bore define a fourth chamber continuously fluidly connected to the pressure source and wherein pressure in the fourth chamber biases the spool toward the second position.

6. The valve of claim 5 wherein pressure in the first chamber biases the spool toward the first position.

7. The valve of claim 6 wherein the spool is mechanically linked to a park mechanism such that the park mechanism is engaged whenever the spool is in the first position and disengaged whenever the spool is in the second position.

8. The valve of claim 1 wherein the spring is a Belleville spring.

9. A park system comprising:

a spool supported to slide within a bore and mechanically linked to a parking pawl; and

an end-cap held in a neutral position with respect to the bore by a spring, wherein the end-cap, spool, and bore define a first chamber and the spring deforms in response to pressure in the first chamber such that the end-cap slides with respect to the bore from the neutral position.

10. The park system of claim 9 further comprising a first check valve alternately fluidly connecting the first chamber to a first clutch apply circuit and an out-of-park circuit based on relative pressure between the first clutch apply circuit and the out-of-park circuit.

11. The park system of claim 10 wherein:

the spool and the bore define a second chamber continuously fluidly connected to the out-of-park circuit;

the bore defines a first port fluidly connecting the second chamber to a pressure source whenever the spool is in an out-of-park position;

the bore defines a second port venting the second chamber whenever the spool is in a park position; and

the first and second ports are both closed when the spool is in an intermediate position between the out-of-park and park positions.

12. The park system of claim 11 wherein the sliding of the end-cap with respect to the bore permits the spool to move from the intermediate position toward the park position without changing a volume of the first chamber thereby opening the second port.

13. The park system of claim 12 wherein the spool and the bore define a third chamber continuously fluidly connected to the pressure source and wherein pressure in the third chamber biases the spool toward the park position.

14. The park system of claim 13 wherein:

the end-cap, spool, and bore define a fourth chamber; and

the spring deforms in response to fluid pressure in the fourth chamber such that the end-cap slides with respect to the bore from the neutral position permitting the spool to move from the intermediate position toward the park position without changing a volume of the fourth chamber thereby opening the second port.

15. The park system of claim 14 further comprising a second check valve alternately fluidly connecting the fourth chamber to a second clutch apply circuit and the out-of-park circuit based on relative pressure between the second clutch apply circuit and the out-of-park circuit.

16. The park system of claim 9 wherein the spring is a Belleville spring.

17. A method of operating a valve wherein a bore, a spool, and an end-cap define a first chamber and the spool and the bore define a second chamber fluidly connected to the first chamber, the method comprising:

sliding the spool into a first position which closes all ports to the second chamber except a first port fluidly connecting it to the first chamber;

applying force to the spool pressurizing fluid in the first and second chambers; and

deflecting a spring to permit the end-cap to slide with respect to the bore and thereby permitting further movement of the spool into a second position which opens a second port venting the second chamber.

18. The method of claim 17 further comprising:

sliding the spool into a third position wherein a parking mechanism linked to the spool is engaged; and

returning the end-cap to a neutral position.