Apparatus and method for controlling creep torque in a power train of a motor vehicle

• US 6,113,515 A
• Filed: 04/30/1998
• Issued: 09/05/2000
• Est. Priority Date: 04/30/1997
• Status: Expired due to Term

• Current Assignee: Schaeffler Technologies AG & Co.KG (INA-Holding Schaeffler GmbH & Co. KG)
• Original Assignee: Luk Getriebe-Systeme GmbH (INA-Holding Schaeffler GmbH & Co. KG)
• Inventors: Amendt, Oliver, Jager, Thomas, Salecker, Michael
• Primary Examiner(s): Marmor, Charles A
• Assistant Examiner(s): Parekh, Ankur
• Application Number:
  US09/070,050
• Time in Patent Office: 859 Days
• Field of Search: 477/72, 477/74, 477/76, 477/171, 477/174-177, 192/3.55-3.57, 192/3.58, 192/3.61-3.63, 192/82 T
• US Class Current: 477/72
• CPC Class Codes: B60W 2510/0291 Clutch temperature
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/023 Clutch engagement rate
• CPC Class Codes: B60W 2710/027 Clutch torque
• CPC Class Codes: B60W 2710/065 Idle condition
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: B60W 30/18063 Creeping
• CPC Class Codes: F16D 2500/30405 Estimated clutch temperature
• CPC Class Codes: F16D 2500/50215 Brake pedal
• CPC Class Codes: F16D 2500/5106 Overheat protection
• CPC Class Codes: F16D 2500/7044 Output shaft torque
• CPC Class Codes: F16D 48/064 Control of electrically or electromagnetically actuated clutches F16D48/062, F16D48/068 take precedence

Abstract

The power train of a motor vehicle has an automated clutch and a control unit which causes one or more actuators to change the rate of torque transmission by the clutch from the engine to the transmission of the power train in response to appropriate signals from various sensors. When the transmission is shifted into gear while the engine is idling, while the brake or brakes are not applied and while the gas pedal is not depressed, the setting of the clutch is such that the transmission causes the motor vehicle to carry out a crawling movement as a result of a change of the rate of torque transmission by the clutch from the idling engine to the transmission from a first value (e.g., zero) to a second value as a function of the monitored temperature of the clutch.

Claims

1. A power train for use in motor vehicles having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

an energy consuming prime mover having inoperative and operative conditions including an idling condition;

means for supplying energy to said prime mover, said energy suplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated variable-temperature torque transmitting system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, including means for monitoring the temperature of said system, said control unit being arranged to transmit to said at least one actuator signals which initiate and effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value as a function of the monitored temperature of said system.

2. The power train of claim 1, wherein said torque transmitting system comprises at least one of (a) at least one clutch and (b) a hydrokinetic torque converter.

3. The power train of claim 1, wherein said temperature monitoring means comprises at least one first sensor and said signal transmitting means further comprises at least one of (a) a plurality of additional sensors and (b) a plurality of circuits.

4. The power train of claim 3, wherein one of said circuits includes a control circuit for said prime mover.

5. The power train of claim 4, wherein said one circuit forms part of said energy supplying means.

6. The power train of claim 1, wherein said at least one second value of said amount of torque transmission is a maximum value.

7. The power train of claim 1, wherein the motor vehicle is arranged to be driven at a plurality of speeds and said prime mover is arranged to transmit a variable torque, said change of amount of torque transmission from said at least one first value being further a function of at least one of:

the speed of the motor vehicle, the magnitude of torque being transmitted by said prime mover, a preselectable value, and at least one vehicle parameter other than speed.

8. The power train of claim 1, wherein said at least one first value of the amount of torque transmission by said system is at least close to zero.

9. The power train of claim 1, wherein said system has engaged and disengaged conditions and an engagement point at which the transmission of torque begins, said at least one first value of the amount of torque transmission by said system corresponding to an amount at said engagement point.

10. The power train of claim 1, wherein said at least one first value of the amount of torque transmission by said system corresponds to a value of torque transmission prior to initiation of said crawling movement of the motor vehicle by way of the power train.

11. The power train of claim 1, wherein said system is arranged to change the amount of torque transmission from said at least one first value to a plurality of second values including a maximum value in accordance with the equation

12. The power train of claim 1, wherein said system is arranged to change the amount of torque transmission from said at least one first value to a plurality of second values including a maximum value, the temperature of said system being variable within a range of temperatures and said system being arranged to vary said amount of torque transmission within said range of temperatures as at least one function of said temperature in accordance with the equation

13. The power train of claim 12, wherein said at least one function is a linear function.

14. The power train of claim 12, wherein said at least one function is one of non-linear functions including exponential, square and stepped functions.

15. The power train of claim 12, wherein said system is arranged to reduce the second value of said amount of torque transmission in response to a drop of monitored temperature of said system.

16. The power train of claim 12, wherein said system is arranged to reduce the second value of said amount of torque transmission in response to an increase of monitored temperature of said system.

17. The power train of claim 1, wherein said system is arranged to change said amount of torque transmission from said at least one first value to a plurality of second values and the temperature of said system is variable within a range of temperatures including at least one threshold value which divides said range of temperatures into a plurality of narrower ranges, said second values within at least one of said narrower ranges being independent of the monitored temperature of said system.

18. The power train of claim 17, wherein said narrower ranges include a first range and a second range, said first range including including a maximum value and at least one second value within said first range being independent of the monitored temperature of said system.

19. The power train of claim 18, wherein said narrower ranges further include a third range, the second values within said second range being a function of the monitored temperature of said system and the second values within said third range being independent of the monitored temperature of said system.

20. The power train of claim 19, wherein the second values within said third range are at least close to zero.

21. The power train of claim 20, wherein said first range of temperatures is lower than at least one of said second and third ranges.

22. The power train of claim 18, wherein said first range of temperatures is lower than said second range.

23. The power train of claim 18, wherein the amount of torque transmission by said system is arranged to decrease within said second range of temperatures as a function of changes of the monitored temperature.

24. The power train of claim 18, wherein said system is arranged to vary the amount of torque transmission within said first range as a linear function of the monitored temperature of said system.

25. The power train of claim 18, wherein said system is arranged to vary the amount of torque transmission within said first range as a non-linear function of the monitored temperature of said system, said non-linear function being one of a plurality of functions including exponential, square and stepped functions.

26. The power train of claim 1, wherein said means for monitoring the temperature of said system includes at least one sensor.

27. The power train of claim 1, wherein said means for monitoring the temperature of said system includes means for indirectly monitoring said temperature.

28. The power train of claim 27, wherein said system includes an engageable and disengageable friction clutch having rotary driving and driven components which are in frictional sliding engagement with each other in each of a plurality of partially engaged conditions of the clutch with attendant generation of heat, said control unit including means for calculating the temperature of said system on the basis of the quantity of generated heat.

29. The power train of claim 28, wherein said clutch has a thermal capacity which influences the calculation of the temperature of said system.

30. The power train of claim 28, wherein said driving components include at least one flywheel which receives torque from said prime mover.

31. The power train of claim 1, wherein the vehicle is a multi-speed vehicle and the amount of torque transmission by said system is further a function of at least one of a plurality of parameters including the speed of the motor vehicle, the torque of said prime mover while the vehicle is in motion, the idling torque of said prime mover, a difference between the torques being transmitted by said prime mover, the RPM of a rotary component of the prime mover while the vehicle in in motion, the RPM of a rotary component of the prime mover while the prime mover is idling, the RPM of a rotary component of said transmission, the difference between the RPMs of the components of said prime mover and said transmission, and time.

32. The power train of claim 1, wherein said system comprises an engageable and disengageable friction clutch and said amount of torque transmission is dependent upon the extent of engagement of said clutch by said at least one actuator, said amount of torque transmission being arranged to increase in response to increasing engagement and to decrease in response to decreasing engagement of said clutch, at least one of said increase and decrease being arranged to vary as a function of time at least within a portion of the duration of said at least one of said increase and said decrease.

33. The power train of claim 1, wherein said system comprises an engageable and disengageable friction clutch and said amount of torque transmission is dependent upon the extent of engagement of said clutch by said at least one actuator, said amount of torque transmission being arranged to increase in response to increasing engagement and decrease in response to decreasing engagement of said clutch, at least one of said increase and said decrease being arranged to vary within at least two intervals of time in accordance with at least two different functions of time.

34. The power train of claim 33, wherein said amount of torque transmission is arranged to increase from a value at least close to zero to a preselected value within one of said intervals and to depart from said preselected value within another of said intervals.

35. The power train of claim 33, wherein said amount of torque transmission is arranged to decrease from a first predetermined value to a second predetermined value within one of said intervals of time and from said second predetermined value at least close to zero within another of said intervals.

36. The power train of claim 1, wherein the motor vehicle is a multi-speed vehicle and said system comprises an engageable and disengageable friction clutch, said amount of torque transmission being dependent upon the extent of engagement of said clutch by said at least one actuator, said amount of torque transmission being arranged to increase in response to increasing engagement and to decrease in response to decreasing engagement of said clutch, the extent of at least one of said increase and decrease being arranged to vary within at least two intervals of time as a function of at least one of a plurality of parameters including the speed of the motor vehicle, the torque of the prime mover in the idling condition, the RPM of a rotary component of the prime mover in an operative condition other than idling, the RPM of a rotary component of the prime mover during idling, and time.

37. The power train of claim 36, wherein said extent increases in response to an increase of the RPM of said rotary component of said prime mover during idling in accordance with one of linear and non-linear functions of at least one of said plurality of parameters, said nonlinear functions including exponential, square and stepped functions.

38. The power train of claim 36, wherein said extent of at least one of said increase and said decrease increases as a function of the RPM of a rotary component of the prime mover during idling in such a way that the extent increases at a lower rate in response to increasing RPM of said rotary component of the prime mover during idling.

39. The power train of claim 1, wherein said motor vehicle is a multi-speed vehicle and said system comprises an engageable and disengageable friction clutch, said amount of torque transmission being dependent upon the extent of engagement of said clutch by said at least one actuator and said amount of torque transmission being arranged to increase in response to increasing engagement and decrease in response to decreasing engagement of said clutch, the rate of at least one of said increase and said decrease being a function of at least one of a plurality of parameters including the speed of the motor vehicle, the torque of the prime mover in the idling condition, the RPM of a rotary component of the prime mover in an operative condition other than idling, the RPM of a rotary component of the prime mover during idling, and time.

40. The power train of claim 39, wherein said rate of at least one of said increase and said decrease increases as a function of the RPM of a rotary component of the prime mover during idling in such a way that the rate increases at a lower rate in response to increasing RPM of said rotary component of the prime mover during idling.

41. The power train of claim 39, wherein said rate increases in response to an increase of the RPM of said rotary component of said prime mover during idling in accordance with one of linear and non-linear functions of at least one of said plurality of parameters, said nonlinear functions including exponential, square and stepped functions.

42. The power train of claim 39, wherein the rate of at least one of said increase and said decrease increases as a function of variations of said RPM of a component of said prime mover during idling so that the rate of said increase rises in response to a rise of said RPM of a component of said prime mover during idling.

43. The power train of claim 42, wherein said rate of said increase rises as one of linear and non-linear functions of at least one of said plurality of parameters, said non-linear functions including exponential, square and stepped functions.

44. The power train of claim 39, wherein said rate of said increase is regulated to raise the rate of rise of crawling torque as a function of the difference between the actual idling RPM of a component of said prime mover and the idling RPM of such component while the prime mover is heated.

45. The power train of claim 44, wherein said rate of increase is regulated to raise the rate of rise of crawling torque at a lower rate in response to increasing difference between said actual idling RPM and the idling RPM while the prime mover is heated.

46. The power train of claim 45, wherein said raise at said lower rate is effected in accordance with one of linear and non-linear functions of at least one of said plurality of parameters, said non-linear functions including exponential, square and stepped functions.

47. The power train of claim 45, wherein said rate of rise of crawling torque is inversely proportional to said difference between said actual RPM and the idling RPM while the prime mover is heated.

48. A power train for use in a variable-speed motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

an energy consuming prime mover arranged to transmit torques of different magnitudes and having inoperative and operative conditions including an idling condition;

means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated variable-temperature torque transmitting system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit including means for monitoring the temperature of said system, means for monitoring a first parameter including the speed of the motor vehicle, means for monitoring the magnitude of the torque being transmitted by said prime mover, and means for monitoring at least one further parameter of the motor vehicle, said control unit being arranged to transmit to said at least one actuator signals which initiate and effect a crawling movement of the motor vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value as a function of at least one of (a) at least one of said monitored parameters, (b) said monitored magnitude of torque being transmitted by said prime mover, and (c) a preselectable value, said amount of torque transmission by said system including a maximum amount which is a function of the monitored temperature of said system.

49. A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

an energy consuming variable-RPM prime mover having inoperative and operative conditions including an idling condition;

means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated torque transmitting system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the motor vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value, said signal transmitting means including means for monitoring the RPM of said prime mover at least while the motor vehicle is crawling and said control unit being arranged to increase said amount of transmission while the RPM of said prime mover is above a predetermined threshold value.

50. A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

an energy consuming variable-RPM prime mover having inoperative and operative conditions including an idling condition;

means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated torque transmitting system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value, said signal transmitting means comprising means for monitoring the RPM of said amount of torque transmission while the motor vehicle is crawling and said control unit being arranged to increase said at least one first value while the RPM of said prime mover is above a first threshold value and to at least slightly reduce the rate of torque transmission when the RPM of said prime mover decreases below a second threshold value.

51. The power train of claim 50, wherein the RPM of said prime mover in said idling condition of said prime mover exceeds said first threshold value by a predetermined amount.

52. The power train of claim 51, wherein said first threshold value exceeds said second threshold value.

53. The power train of claim 50, wherein said control unit is arranged to increase the amount of torque transmission by said system in response to a change of the RPM of said prime mover from said second threshold value to a third threshold value.

54. The power train of claim 53, wherein the RPM of said prime mover in said idling condition of the prime mover exceeds said third threshold value by a predetermined amount and said third threshold value exceeds said second threshold value.

55. The power train of claim 53, wherein said third threshold value at least approximates said first threshold value.

56. A power train for use in a motor vehicle, said power train comprising:

an energy consuming prime mover having inoperative and operative conditions including an idling condition;

means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated torque transmitting system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value within a predetermined period of time, wherein said second value corresponds to an amount of torque transmission at which the motor vehicle begins to carry out said crawling movement.

57. A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

an energy consuming prime mover having inoperative and operative conditions;

means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated torque transmission system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake, in the inoperative condition of said energy supplying means and while said prime mover is idling to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value at which the motor vehicle proceeds to carry out said crawling movement until the application of said at least one brake which entails a reduction of said at least one second value as a function of time, said control unit being further arranged to set said amount at a predetermined third value in response to a termination of the application of said at least one brake prior to a reduction of said amount all the way to zero.

58. A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

an energy consuming prime mover having inoperative and operative conditions;

means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated torque transmitting system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle, by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake and in the inoperative condition of said energy supplying means to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value at which the motor vehicle proceeds to carry out said crawling movement until the application of said at least one brake which entails a reduction of said amount of torque transmission from said at least one second value as a function of time, said control unit being further arranged to set said amount back to said second value in response to a termination of the application of said at least one brake prior to a reduction of said amount of torque transmission to zero.

59. A power train for use in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, said power train comprising:

an energy consuming prime mover having inoperative and operative conditions;

means for supplying energy to said prime mover, said energy supplying means having idle and operative conditions;

a transmission shiftable into and from a plurality of gears;

an automated torque transmitting system connected with at least one of said prime mover and said transmission; and

means for operating said system, including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from said control unit, and means for transmitting signals to said control unit, said control unit being arranged to transmit to said at least one actuator signals which effect a crawling movement of the vehicle by way of said power train when said transmission is in gear, said prime mover assumes said operative condition in the non-applied condition of said at least one brake and in the inoperative condition of said energy supplying means to thus induce said system to change, in response to shifting of said transmission into gear, the amount of torque transmission from at least one first value to at least one second value at which the motor vehicle proceeds to carry out said crawling movement until the application of said at least one brake which entails a reduction of said at least one second value toward zero, said control unit being further arranged to change said amount to a maximum permissible third value in response to a termination of the application of said at least one brake prior to reduction of said at least one second value all the way to zero.

60. The power train of claim 59, wherein said third value exceeds said at least one second value.

61. A method of operating a power train in a motor vehicle having at least one brake arranged to assume applied and non-applied conditions, the power train comprising an energy consuming prime mover having inoperative and operative conditions including an idling condition, means for supplying energy to the prime mover, said energy supplying means having idle and operative conditions, a transmission shiftable into and from a plurality of gears, an automated variable-temperature torque transitting system connected with at least one of said prime mover and said transmission, and means for operating said system including a signal receiving, processing and transmitting control unit, at least one actuator arranged to select the amount of torque transmission by said system in response to signals from the control unit, and means for transmitting signals to the control unit including means for monitoring the temperature of said system, comprising the steps of:

shifting the transmission in gear;

causing the prime mover to assume the operative condition;

maintaining the at least one brake in the non-applied condition;

causing the energy supplying means to assume the inoperative condition; and

as a result of shifting the transmission in gear, causing the control unit to transmit to the at least one actuator signals which effect a crawling movement of the motor vehicle by way of the power train to thus induce said system to change the amount of torque transmission from at least one first value to at least one second value as a function of monitored temperature of said system.