Pressure-responsive displacement changer for vehicular drive system having a variable displacement pump

• US 3,874,470 A
• Filed: 05/31/1973
• Issued: 04/01/1975
• Est. Priority Date: 05/31/1973
• Status: Expired due to Term

• Current Assignee: Clarence Kirk Greene
• Original Assignee: Clarence Kirk Greene
• Inventors: Greene, Clarence Kirk
• Primary Examiner(s): Schonberg, David
• Assistant Examiner(s): Siemens, Terrance L.
• Application Number:
  US05/365,493
• Time in Patent Office: 670 Days
• Field of Search: 180/14K,14A,14D,53R,44F,44M,22,53CD,66R
• US Class Current: 180/14.3
• CPC Class Codes: B62D 53/0871 with stabilising means, e.g. to prevent jack-knifing, pitching, rolling, buck jumping stabilising in general B62D37/00; tractors B62D49/08
• CPC Class Codes: B62D 59/04 driven from propulsion unit on trailer
• CPC Class Codes: F16H 61/472 for achieving a target output torque

Abstract

A drive system for vehicle means, e.g., a truck-trailer combination, having primary and secondary driving elements and a power plant, includes a torque divider having an input shaft driven by the power plant, a first output which drives the primary driving element mechanically and a second output including a variable displacement pump having displacement changing means and interconnected to a hydraulic motor which drives the secondary driving element, and means for reducing the pump displacement upon a rise in the hydraulic pressure in the interconnecting duct which is normally at the lower pressure, i.e., the normal return duct. Automatic displacement change is effected by a movable wall exposed to the pressure in the said duct; this wall may be a single-action piston, or may be opposed by the pressure in the other duct, so that the wall moves in response to the difference in hydraulic pressures in the two interconnecting ducts.

Claims

1. In a self-propelled vehicle means having a power plant, a primary driving element situated on one transverse axis and a secondary driving element situated on another transverse axis, a drive system which includes:

a. a torque divider having an input drivenly coupled to said power plant, a first output coupled to the said primary driving element, and a second output coupled to a pump, a hydraulic motor coupled drivingly to the secondary driving element, and interconnecting supply and return ducts between the pump and the motor for driving the motor from the pump, and b. means sensitive to the pressure within the return duct for increasing the pressure within said duct upon a rise in the pressure therein.

2. The drive means according to claim 1 wherein said means sensitive to the pressure is exposed opposedly to the pressures resulting from the separate pressures in the said supply and return ducts, whereby said means acts to increase the pressure in said return duct in response to an increase in the pressure in the return duct with reference to the pressure in the supply duct.

3. The drive system according to claim 1 wherein said vehicle means is a truck-trailer combination, said primary driving element includes at least one wheel of the truck and said secondary driving element includes at least one wheel of a trailer, said hydraulic motor being mounted on the trailer.

4. The drive system according to claim 1 wherein said means sensitIve to the pressure includes a chamber containing a movable piston which is connected by an auxiliary duct to the return duct, wherein said pump has a variable displacement and includes a displacement-changing member, and the said piston is connected to said displacement-changing member to reduce the pump displacement upon a rise in the pressure within said return duct.

5. In combination with the drive system according to claim 1 wherein said pump has a variable displacement and said means sensitive to the pressure in the return duct is connected to vary the pump displacement, means operable from the vehicle means for locking the pump displacement into a selected position, said last-mentioned means being constructed and arranged to be rendered inoperative to permit the first-mentioned means to control the pump displacement.

6. In a self-propelled vehicle means having a power plant, a primary driving element situated on one transverse axis and a secondary driving element situated on another transverse axis, a drive system which includes:

a. a differential torque divider having an input drivenly coupled to said power plant, a first output coupled to the said primary driving element, and a second output coupled to a pump, a hydraulic motor coupled drivingly to the secondary driving element, and interconnecting supply and return ducts between the pump and the motor for driving the motor from the pump, and b. means sensitive to the pressure in the return duct for increasing the pressure within said duct.

7. In a self-propelled vehicle means having a power plant, a primary driving element situated on one transverse axis and a secondary driving element situated on another transverse axis, a drive system which includes:

a. a differential torque divider having an input shaft drivenly coupled to said power plant, a first output mechanically coupled to the primary driving element, a positive and variable displacement pump mechanically and drivenly coupled to a second output and having a movable displacement-varying member, a hydraulic motor coupled drivingly to the secondary driving element, and interconnecting supply and return ducts between the pump and the motor for driving the motor from the pump, and b. means for varying the pump displacement including a movable, pressure-responsive wall connected to said displacement-varying member, walls enclosing a chamber to which said movable wall is exposed, and auxiliary duct means interconnecting said chamber to one of said interconnecting ducts.

8. The combination according to claim 7 wherein said vehicle means is a truck-trailer combination, said primary driving element includes at least one wheel of the truck and the secondary driving element includes at least one wheel of the trailer, said hydraulic motor being mounted on the trailer.

9. The drive system according to claim 8 wherein said chamber is a cylinder and the movable wall is a piston, wherein a. said piston is connected to the pump displacement-varying member so as to reduce the pump displacement as the piston moves to expand the space within the cylinder, and b. said auxiliary duct means is interconnected between the said cylinder space and the return duct, which return duct is normally at a lower pressure than the supply duct when the vehicle is moving forwardly under power.

10. The drive system according to claim 9 which includes resilient means for urging the piston in a direction to increase the pump displacement.

11. The drive system according to claim 7 wherein a. said chamber includes at least one cylinder and the movable wall includes a piston means having opposed faces, said movable wall being connected to the pump displacement-varying member so as to reduce the pump displacement when the wall moves in one direction, and b. said auxiliary duct means includes first and second, separate auxiliary ducts interconnecting parts of the cylinder on opposite sides of the piston means with the supply and return ducts so that the pressure within the return duct, which is normally at a lower pressure than the supply duct when the vehicle means is moving forwardly under power tends to reduce the pump displacement.

12. The drive system according to claim 11 which includes resilient means for urging the piston means in a direction opposite to said direction which increased the pump displacement.

13. The drive system according to claim 7 which includes stop means for limiting the extent of movement of the movable wall to a distance less than that which would reduce the pump displacement to zero.

14. The drive system according to claim 7 which includes means operable from the vehicle for varying the displacement of the pump, said means being connected to the displacement-varying member of the pump.

15. The drive system according to claim 7 wherein said said vehicle means is a truck-trailer combination, said primary driving element includes at least one wheel of the truck and the secondary driving element includes at least one wheel of the trailer, said drive system including a. means operable manually from the vehicle operator'"'"''"'"'s compartment for varying the pump displacement from low to maximum, and b. stop means for limiting the extent of movement of the movable wall to a distance less than that which would reduce the pump displacement to zero.

16. In the drive system according to claim 7, flow-restrictive means interposed in said auxiliary duct means for causing said movable wall to move slowly upon a change in pressure in said interconnecting duct.