Hydromechanical transmission electronic control system for high speed vehicles

• US 20050085979A1
• Filed: 11/04/2004
• Published: 04/21/2005
• Est. Priority Date: 07/18/2002
• Status: Active Grant

• Current Assignee: Danfoss Power Solutions Inc. (Danfoss A/S)
• Original Assignee: Sauer-Danfoss Incorporated (Danfoss A/S)
• Inventors: Maiers, Manfred, Carlson, Ryan R., Gluck, Steven H.
• Granted Patent: US 6,942,596 B2
• Time in Patent Office: Days
• US Class Current: 701/51
• CPC Class Codes: B60W 2510/0604 Throttle position
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: F16H 2037/088 Power split variators with summing differentials, with the input of the CVT connected or connectable to the input shaft
• CPC Class Codes: F16H 2059/6853 the state of the transmission units, i.e. motor or pump capacity, e.g. for controlled shifting of range gear
• CPC Class Codes: F16H 47/04 the mechanical gearing being of the type with members having orbital motion
• CPC Class Codes: F16H 59/24 dependent on the throttle opening
• CPC Class Codes: F16H 59/44 dependent on machine speed of the machine, e.g. the vehicle
• CPC Class Codes: F16H 59/54 dependent on signals from the brakes, e.g. parking brakes
• CPC Class Codes: F16H 59/68 Inputs being a function of gearing status
• CPC Class Codes: F16H 61/4043 Control of a bypass valve
• CPC Class Codes: F16H 61/42 involving adjustment of a pump or motor with adjustable output or capacity F16H61/46 takes precedence
• CPC Class Codes: F16H 61/462 for achieving a target speed ratio

Abstract

An electronic transmission control system is provided that can achieve a transmission ratio based on the operator inputs and the current vehicle operating conditions. The transmission constantly connects the engine to the load, and the transmission ratio is only varied by a change in command from the present invention. The transmission'"'"'s mechanical function is solely to vary the ratio between its input and output. In using the present invention, an operator must select an operating mode, either automatic or manual, using a two-position switch. While in the automatic mode, the present invention determines the vehicle speed by considering the position of the throttle and the operator'"'"'s use of brakes. In the manual mode, the present invention further considers the operator'"'"'s selection of a gear condition.

Claims

1. A control for a hydrostatic transmission having a swashplate and connecting an engine to a pair of wheels on a vehicle, wherein said engine has an engine speed, said wheels rotate to cause a rotation, and said vehicle is operating at varying speeds, the control comprising:

a throttle having varying positions that vary the rotation of the wheels;

a brake having varying positions that varies the rotation of the wheels;

means for sensing a position of the throttle and converting the throttle position to a commanded engine speed;

means for sensing a position of the brake;

means for sensing the speed of the vehicle;

an electronic control unit that receives the commanded engine speed, brake position, and vehicle speed and sets a swashplate position, wherein the swashplate position is determined by the commanded engine speed and brake position when the vehicle is accelerating and by the vehicle speed and brake position when the vehicle is decelerating; and

means for sensing the position of the swashplate and adjusting the position of the swashplate as determined by the electronic control unit.

2. The control of claim 1 further comprising means for sensing the speed of the engine.

5. The control of claim 1 further comprising a gear selector to select a gear ratio.

6. The control of claim 5, wherein the electronic control unit further receives the gear ratio and sets the position of the swashplate, wherein the swashplate position is determined by the commanded engine speed and brake position when the vehicle is accelerating and by the vehicle speed and brake position when the vehicle is decelerating.

3. (canceled)

4. The control of claim 3, wherein the electronic control unit reduces the set position of the swashplate.

7. A hydromechanical transmission for connecting an engine to a pair of wheels on a vehicle, the hydromechanical transmission comprising:

a hydraulic pump and a hydraulic motor connected with each other through a closed hydraulic loop on a driving shaft, the pump including a driven gear for being rotated by a driving gear mounted on a crank shaft of the engine;

said engine having an engine speed;

said wheels rotate to cause a rotation;

said vehicle is operating at varying speeds;

a swashplate having varying swashplate positions in connection with the pump;

a throttle having varying positions that vary the rotation of the wheels;

a brake having varying positions that varies the rotation of the wheels;

means for sensing the position of the throttle and converting the throttle position to a commanded engine speed;

means for sensing the position of the brake;

means for sensing the speed of the vehicle; and

an electronic control unit that receives the commanded engine speed, brake position, and vehicle speed and sets the swashplate position, wherein the swashplate position is determined by the commanded engine speed and brake position when the vehicle is accelerating and by the vehicle speed and brake position when the vehicle is decelerating; and

means for sensing the swashplate position and adjusting the swashplate position as determined by the electronic control unit.

8. The hydromechanical transmission of claim 7 further comprising means for sensing the speed of the engine.

11. The hydromechanical transmission of claim 7 further comprising a gear selector to select a gear ratio.

12. The hydromechanical transmission of claim 11, wherein the electronic control unit further receives the gear ratio and sets the position of the swashplate, wherein the swashplate position is determined by the commanded engine speed and brake position when the vehicle is accelerating and by the vehicle speed and brake position when the vehicle is decelerating.

9. (canceled)

10. The hydromechanical transmission of claim 9, wherein the electronic control unit reduces the set position of the swashplate.

13. A method of controlling a hydromechanical transmission having a swashplate that has varying swashplate positions, an operator-controlled throttle that has varying throttle positions, and an operator-controlled brake that has varying position, on a vehicle that has a varying vehicle speed, the method comprising:

sensing the position of the throttle;

converting the throttle position to a commanded engine speed by comparing the throttle position against a predicted no-load engine RPM;

sensing the speed of the vehicle;

sensing the position of the brake;

sensing the position of the swashplate;

taking the commanded engine speed, vehicle speed, and brake position to determine a vehicle situation; and

setting the swashplate position for the vehicle situation, wherein the commanded engine speed and brake position determine the swashplate position when the vehicle situation is accelerating and the vehicle speed and brake position determine the swashplate position when the vehicle situation is decelerating.

14. The method of claim 13 wherein the vehicle has an engine speed and the method further comprising the step of sensing the speed of the engine.

17. The method of claim 13, wherein an operator-controlled gear ratio also is used to determine the vehicle situation.

15. (canceled)

16. The method of claim 15 further comprising reducing the set position of the swashplate.