Control apparatus and method for vehicle having an idle stop function

• US 20030045988A1
• Filed: 08/27/2002
• Published: 03/06/2003
• Est. Priority Date: 08/31/2001
• Status: Active Grant

• Current Assignee: Aisin AW Company Limited (Aisin Corp.)
• Original Assignee: Aisin AW Company Limited (Aisin Corp.)
• Inventors: Suzuki, Takehiko, Kubo, Takayuki, Inuzuka, Takeshi, Wakuta, Satoru
• Granted Patent: US 6,556,910 B2
• Time in Patent Office: Days
• US Class Current: 701/54
• CPC Class Codes: B60K 6/485 Motor-assist type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: F02N 11/0818 Conditions for starting or stopping the engine or for deactivating the idle-start-stop mode
• CPC Class Codes: F02N 11/0822 related to action of the driver
• CPC Class Codes: F02N 11/084 State of vehicle accessories, e.g. air condition or power steering
• CPC Class Codes: F02N 11/0848 with means for detecting successful engine start, e.g. to stop starter actuation
• CPC Class Codes: F02N 2300/2011 Control involving a delay; Control involving a waiting period before engine stop or engine start
• CPC Class Codes: F16H 2061/0078 Linear control, e.g. PID, state feedback or Kalman
• CPC Class Codes: F16H 2061/0087 Adaptive control, e.g. the control parameters adapted by learning
• CPC Class Codes: F16H 2061/062 for controlling filling of clutches or brake servos, e.g. fill time, fill level or pressure during filling
• CPC Class Codes: F16H 2200/0047 the gear ratios comprising five forward speeds
• CPC Class Codes: F16H 2200/201 with three sets of orbital gears
• CPC Class Codes: F16H 2306/36 Filling the dead volume of actuators
• CPC Class Codes: F16H 2312/00 Driving activities
• CPC Class Codes: F16H 3/666 with compound planetary gear units, e.g. two intermeshing orbital gears F16H3/663 takes precedence
• CPC Class Codes: F16H 61/0031 using auxiliary pumps, e.g. pump driven by a different power source than the engine
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y10S 903/945 : Characterized by control of gearing, e.g. control of transmission ratio

Abstract

A control apparatus for a vehicle which executes an automatic stop control of an engine on the basis of a stop condition, and executes a restart control of the engine on the basis of a start condition. The vehicle includes an engagement element which freely interrupts and establishes power transmission between an output of the engine and a drive wheel, a hydraulic servo which freely operates an engagement state of the engagement element and a control unit which executes a feedback control for bringing a hydraulic pressure of the hydraulic servo into a state immediately before the frictional engagement element is engaged, on the basis of the engagement state of the engagement element wherein the control unit starts the feedback control after the hydraulic pressure of the hydraulic servo is controlled to a predetermined hydraulic pressure when the restart control of the engine is executed.

Claims

1. A control apparatus for a vehicle which executes an automatic stop control of an engine on the basis of a stop condition, and executes a restart control of the engine on the basis of a start condition, comprising:

an engagement element which freely interrupts and establishes power transmission between an output of the engine and a drive wheel;

a hydraulic servo which freely operates an engagement state of the engagement element; and

a control unit which executes a low pressure control for bringing a hydraulic pressure of the hydraulic servo into a state immediately before the engagement element is engaged at a time when the restart control of the engine is executed while the vehicle is being stopped and the automatic stop control of the engine is being executed.

2. The control apparatus as claimed in claim 1, further comprising:

an automatic transmission which is interposed between an input shaft to which an output of the engine is input and the drive wheel, has a transmission unit which can execute a changeover of a transmission path using a fluid transmission device and a plurality of engagement elements, and changes speed of rotation of the input shaft on the basis of engagement and disengagement of the plurality of engagement elements so as to output the rotation of the input shaft to the drive wheel, wherein the engagement element is an input clutch which is engaged with at least a forward first speed stage out of the plurality of engagement elements so as to transmit the rotation of the input shaft.

3. The control apparatus as claimed in claim 1, wherein the low pressure control is a fixed pressure control for controlling the hydraulic pressure of the hydraulic servo to a fixed target pressure.

4. The control apparatus as claimed in claim 3, wherein the control unit executes a feedback control for bringing a hydraulic pressure of the hydraulic servo into a state immediately before the engagement element is engaged on the basis of the engagement state of the engagement element, and starts the feedback control after the hydraulic pressure of the hydraulic servo is controlled to the fixed target pressure when the restart control of the engine is executed.

5. The control apparatus as claimed in claim 4, wherein the control unit stores the hydraulic pressure when the feedback control is executed, and executes learning so that the control unit can execute the low pressure control on the basis of the stored hydraulic pressure.

6. The control apparatus as claimed in claim 4, further comprising a detecting unit which detects a difference in rotation number between a rotation number of the engine and a rotation number of the input shaft, wherein the control unit detects an engagement state of the engagement element on the basis of a detection result of the detecting unit, and executes the feedback control.

7. The control apparatus as claimed in claim 6, wherein the control unit executes the feedback control on the basis of a rate of change in the rotation number difference which is detected by the detecting unit.

8. The control apparatus as claimed in claim 6, wherein the control unit executes the feedback control so that the rotation number difference detected by the detecting unit becomes equal to a target rotation number difference.

9. The control apparatus as claimed in claim 6, wherein the control unit increases the hydraulic pressure of the hydraulic servo in stages in the case that a change rate of the rotation number difference which is detected by the detecting unit is equal to or less than a predetermined threshold value, and decreases the hydraulic pressure of the hydraulic servo by one stage in the case that the change rate of the rotation number difference which is detected by the detecting unit is equal to or more than a predetermined threshold value, and stores a hydraulic pressure that is one stage below the hydraulic pressure of the hydraulic servo in the case that the change rate of the rotation number difference is equal to or more than the predetermined threshold value.

10. The control apparatus as claimed in claim 5, wherein the control unit executes a learning control such that the low pressure control is executed next time on the basis of a hydraulic pressure that is finally stored out of hydraulic pressures that are stored during the execution of the feedback control.

11. The control apparatus as claimed in claim 1, comprising:

a judging unit which judges a condition for starting the engine; and

a starting unit which starts the engine on the basis of a judgement of the judging unit, wherein the judging unit judges the condition for starting the engine other than a start request, and operates the control unit.

12. The control apparatus as claimed in claim 11, wherein the control unit immediately starts the low pressure control on the basis of a judgment of the judging unit.

13. The control apparatus as claimed in claim 11, wherein the starting unit starts the engine a predetermined time after a judgement of the judging unit.

14. The control apparatus as claimed in claim 11, wherein the judging unit judges the condition for starting the engine, other than the start request, on the basis of one of a reduction in a remaining amount of a battery and a start of an air conditioner.

15. The control apparatus as claimed in claim 11, further comprising:

a detecting unit which detects the start request, wherein the control unit continues the low pressure control until the start request is detected by the detecting unit.

16. The control apparatus as claimed in claim 15, wherein the detecting unit detects the start request on the basis of one of an operation state of a brake pedal and a throttle opening degree.

17. The control apparatus as claimed in claim 1, wherein the engagement element has a plurality of friction plates, the hydraulic servo has a piston which freely presses the plurality of friction plates on the basis of the hydraulic pressure, and the control unit controls the hydraulic pressure so as to close up a gap interposed between the plurality of friction plates and the piston.

18. The control apparatus as claimed in claim 1, comprising:

a pump which freely supplies the hydraulic pressure to the hydraulic servo, wherein the control unit drives and controls the pump on the basis of one of the automatic stop control of the engine and the restart control of the engine during the automatic stop control of the engine.

19. The control apparatus as claimed in claim 18, wherein the engagement element is in an engaged state during the automatic stop control of the engine.

20. The control apparatus as claimed in claim 4, further comprising:

a detecting unit which detects the start request, wherein the control unit cancels the feedback control on the basis of detection of the detecting unit, and increases the hydraulic pressure of the hydraulic servo so as to engage the engagement element.

21. The control apparatus as claimed in claim 4, wherein the control unit sets a start hydraulic pressure for the feedback control to the fixed hydraulic pressure.

22. The control apparatus as claimed in claim 6, further comprising an engine state detecting unit which detects a state of the engine, wherein the control unit starts the feedback control when the engine state detecting unit detects that the start of the engine by an engine starting unit is completed.

23. The control apparatus as claimed in claim 6, further comprising an engine state detecting unit which detects a state of the engine, wherein the control unit starts the feedback control when the engine state detecting unit detects that a rotation number of the engine is equal to or more than a predetermined rotation number.

24. The control apparatus as claimed in claim 4, comprising:

a first pump which is driven according to the engine and freely supplies the hydraulic pressure of the hydraulic servo;

a second pump which freely supplies the hydraulic pressure of the hydraulic servo, wherein the control unit drives and controls the second pump during the automatic stop control of the engine on the basis of one of the automatic stop control of the engine and the restart control of the engine, and the hydraulic pressure of the hydraulic servo is constantly supplied by one of the first pump and the second pump.

25. The control apparatus as claimed in claim 24, wherein the first pump is a mechanical oil pump and the second pump is an electrically driven oil pump.

26. A method of executing an automatic stop control of an engine on the basis of a stop condition, executing a restart control of the engine on the basis of a start condition and controlling an engagement element which freely interrupts and establishes power transmission between an output of the engine and a drive wheel and a hydraulic servo which freely operates an engagement state of the engagement element, comprising:

bringing a hydraulic pressure of the hydraulic servo into a state immediately before the engagement element is engaged, with a low pressure control, at a time when the restart control of the engine is executed while the vehicle is being stopped and the automatic stop control of the engine is being executed.

27. The method of claim 26, wherein the hydraulic pressure of the hydraulic servo is controlled to a fixed target pressure with a fixed pressure control.

28. The method of claim 27, comprising:

bringing a hydraulic pressure of the hydraulic servo into a state immediately before the engagement element is engaged, on the basis of the engagement state of the engagement element; and

starting a feedback control after the hydraulic pressure of the hydraulic servo is controlled to the fixed target pressure when the restart control of the engine is executed.

29. The method of claim 28, comprising:

storing the hydraulic pressure when the feedback control is executed; and

learning so that the low pressure control can be executed on the basis of the stored hydraulic pressure.

30. The method of claim 28, comprising:

detecting a difference in rotation number between a rotation number of the engine and a rotation number of an input shaft;

detecting an engagement state of the engagement element on the basis of a detection result; and

executing the feedback control based on a detected engagement state.

31. The method of claim 30, wherein the feedback control is executed on the basis of a rate of change in the rotation number difference.

32. The method of claim 30, wherein the feedback control is executed so that the rotation number difference becomes equal to a target rotation number difference.

33. The method of claim 30, comprising:

increasing the hydraulic pressure of the hydraulic servo in stages in the case that a change rate of the rotation number difference is equal to or less than a predetermined threshold value;

decreasing the hydraulic pressure of the hydraulic servo by one stage in the case that the change rate of the rotation number difference which is detected by the detecting unit is equal to or more than a predetermined threshold value; and

storing a hydraulic pressure that is one stage below the hydraulic pressure of the hydraulic servo in the case that the change rate of the rotation number difference is equal to or more than the predetermined threshold value.

34. The method of claim 29, wherein a learning control is executed such that the low pressure control is executed next time on the basis of a hydraulic pressure that is finally stored out of hydraulic pressures that are stored during the execution of the feedback control.

35. The method of claim 26, comprising:

judging a condition for starting the engine other than a start request; and

starting the engine on the basis of a judgment.

36. The method of claim 35, wherein the low pressure control is immediately started on the basis of the judgment.

37. The method of claim 35, wherein the engine is started at a predetermined time after a judgment.

38. The method of claim 35, wherein the condition for starting the engine is judged based on one of a reduction in a remaining amount of a battery and a start of an air conditioner.

39. The method of claim 35, wherein the low pressure control is continued until the start request is detected by the start request detecting unit.

40. The method of claim 39, wherein the start request is detected on the basis of one of an operation state of a brake pedal and a throttle opening degree.

41. The method of claim 26, wherein the engagement element has a plurality of friction plates, the hydraulic servo has a piston which freely presses the plurality of friction plates on the basis of the hydraulic pressure, comprising:

controlling the hydraulic pressure so as to close up a gap interposed between the plurality of friction plates and the piston.

42. The method of claim 26, comprising:

supplying the hydraulic pressure freely with a pump to the hydraulic servo;

driving and controlling the pump on the basis of one of the automatic stop control of the engine and the restart control of the engine during the automatic stop control of the engine.

43. The method of claim 42, wherein the engagement element is in an engaged state during the automatic stop control of the engine.

44. The method of claim 28, comprising:

detecting the start request;

canceling the feedback control when the start request is detected; and

increasing the hydraulic pressure of the hydraulic servo so as to engage the engagement element.

45. The method of claim 28, wherein a start hydraulic pressure for the feedback control is set to the predetermined hydraulic pressure.

46. The method of claim 30, wherein the feedback control is started when the start of the engine by an engine starting unit is completed.

47. The method of claim 30, wherein the feedback control is started when a rotation number of the engine is equal to or more than a predetermined rotation number.

48. The method of claim 30, wherein a first pump is driven according to the engine and freely supplies the hydraulic pressure of the hydraulic servo and a second pump a freely supplies the hydraulic pressure of the hydraulic servo, comprising:

driving and controlling the second pump during the automatic stop control of the engine on the basis of one of the automatic stop control of the engine and the restart control of the engine, wherein the hydraulic pressure of the hydraulic servo is constantly supplied by one of the first pump and the second pump.