Torque control method and apparatus for internal combustion engine and motor vehicles employing the same

• US 5,496,227 A
• Filed: 10/07/1994
• Issued: 03/05/1996
• Est. Priority Date: 04/18/1990
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shiraishi, Takashi, Tokuda, Hiroatsu, Kimura, Hiroshi, Ozaki, Naoyuki, Minowa, Toshimichi, Ibamoto, Masahiko, Ishii, Junichi, Ohyama, Yoshishige
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US08/319,719
• Time in Patent Office: 515 Days
• Field of Search: 477/62, 477/110
• US Class Current: 477/62
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 2510/0628 Inlet air flow rate
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: B60W 30/18 Propelling the vehicle
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: F16H 2061/0012 Transmission control for optimising power output of driveline
• CPC Class Codes: F16H 2061/0015 Transmission control for optimising fuel consumptions
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/14 Control of torque converter lock-up clutches

Abstract

Torque control method and apparatus for an internal combustion engine of a motor vehicle. A value of a desired drive shaft torque for the motor vehicle is determined on the basis of at least an accelerator pedal stroke for thereby controlling a drive shaft torque of the motor vehicle so as to assume the desired drive shaft torque value by controlling a gear ratio of a transmission gear coupling an output shaft of the engine to at least a drive shaft of the motor vehicle on the basis of the value of the desired drive shaft torque as determined. A gear ratio of the transmission gear and a flow rate of intake air fed to the engine are determined through different procedures in dependence on whether or not a torque transfer mechanism coupling the output shaft of the engine to an input shaft of the transmission gear is in a lock-up state in which the output shaft and the input shaft are coupled directly without slip. The drive shaft torque of the motor vehicle is so controlled that it assumes the desired drive shaft torque by controlling the transmission gear and engine intake air flow rate such that the determined gear ratio and the determined intake air flow rate can be realized.

Claims

1. A torque control method for an internal combustion engine of a motor vehicle, wherein a value of a desired drive shaft torque for said motor vehicle is determined on the basis of at least an accelerator pedal stroke for thereby controlling a drive shaft torque of said motor vehicle so as to assume said desired drive shaft torque by controlling a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle on the basis of the value of said desired drive shaft torque as determined,

said method comprising the step of:

changing over procedures from one to other for determining a gear ratio of said transmission gear and a flow rate of intake air fed to said internal combustion engine in dependence on whether or not a torque transfer mechanism coupling the output shaft of said internal combustion engine to an input shaft of said transmission gear is in a lock-up state in which said output shaft and said input shaft are coupled directly without slip.

2. A torque control method for an internal combustion engine of a motor vehicle, wherein a value of a desired drive shaft torque for said motor vehicle is determined on the basis of at least an accelerator pedal stroke for thereby controlling a drive shaft torque of said motor vehicle so as to assume said desired drive shaft torque by controlling a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle on the basis of the value of said desired drive shaft torque as determined,

said method comprising the step of:

(a) determining a gear ratio of said transmission gear and a flow rate of intake air fed to said internal combustion engine through different procedures in dependence on whether or not a torque transfer mechanism coupling the output shaft of said internal combustion engine to an input shaft of said transmission gear is in a lock-up state in which said output shaft and said input shaft are coupled directly without slip; and

(b) controlling said drive shaft torque of said motor vehicle so that it assumes said desired drive shaft torque by controlling said transmission gear and engine intake air flow rate such that said determined gear ratio and said determined intake air flow rate can be realized.

3. A torque control method for an internal combustion engine according to claim 2,

wherein said step (a) includes:

a sub-step (a-1) of determining at least one gear ratio at which said determined desired drive shaft torque can be realized at a detected value of vehicle speed of said motor vehicle; and

a sub-step (a-2) of selecting one of the gear ratios as determined at which an optimal fuel cost can be achieved.

4. A torque control method for an internal combustion engine according to claim 3,

wherein in said sub-step (a-2), a map prescribing relations at least among values corresponding to the desired drive shaft torques, the gear ratios of said transmission gear and the flow rates of the intake air fed to said engine is searched on the basis of said determined desired drive shaft torque to thereby select from said gear ratios a gear ratio at which said optimal fuel cost can be achieved.

5. A torque control method for an internal combustion engine according to claim 4,

wherein said step (a) includes a sub-step in which a map prescribing relations at least between values corresponding to the desired drive shaft torques and the intake air flow rates is searched on the basis of the gear ratio selected in said sub-step (a-2) to thereby determine the intake air flow rate for said engine.

6. A torque control method for an internal combustion engine according to claim 2,

wherein when said torque transfer mechanism is in the lock-up state, said step (a) includes the sub-steps of:

(a-1) determining engine rotation numbers for every gear ratio of said transmission gear on the basis of a detected value of said vehicle speed and the gear ratios which said transmission gear has;

(a-2) determining engine torques for every gear ratio of said transmission gear on the basis of said determined desired drive shaft torque and the gear ratios which said transmission gear has;

(a-3) determining at least one gear ratio on the basis of the engine rotation numbers determined for every gear ratio of said transmission gear and the engine torque; and

(a-4) selecting a gear ratio from those determined in said sub-step (a-3) at which an optimal fuel cost can be realized.

7. A torque control method for an internal combustion engine according to claim 6,

wherein said step (a) further includes:

a sub-step (a-5) in which a map prescribing relations existing among the engine rotation numbers, the engine torques and the intake air flow rates is searched on the basis of the gear ratio selected in said sub-step (a-4) to thereby determine the intake air flow rate.

8. A torque control method for an internal combustion engine according to claim 2,

wherein unless said torque transfer mechanism is in the lock-up state, said step (a) includes the sub-steps of:

(a-1) determining output shaft rotation numbers of said torque transfer mechanism for every gear ratio of said transmission gear on the basis of a detected value of said vehicle speed and the gear ratios which said transmission gear has;

(a-2) determining output shaft torques of said torque transfer mechanism for every gear ratio of said transmission gear on the basis of said determined desired drive shaft torque and the gear ratios which said transmission gear has;

(a-3) determining engine rotation numbers and engine torques for every gear ratio of said transmission gear on the basis of said determined output shaft torque, said output shaft rotation number of said torque transfer mechanism and torque transfer characteristics of said torque transfer mechanism;

(a-4) determining at least one gear ratio on the basis of the engine rotation number and said engine torque as determined; and

(a-5) selecting a gear ratio from those determined in said sub-step (a-4) at which an optimal fuel cost can be realized.

9. A torque control method for an internal combustion engine according to claim 8,

wherein said step (a) further includes:

a sub-step (a-6) in which a map prescribing relations existing among the engine rotation numbers, the engine torques and the intake air flow rates is searched on the basis of the gear ratio selected in said sub-step (a-5) to thereby determine the intake air flow rate.

10. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine;

(c) determining a value corresponding to an actual drive shaft torque of said motor vehicle;

(d) correcting at least either one of said gear ratio or said intake air flow rate obtained in said step (b) with a deviation of the value determined in said step (c) from said determined desired drive shaft torque; and

(e) controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as corrected can be realized.

11. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

(c) controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said step (b) includes a sub-step in which when a current manual shift range of said transmission gear includes a plurality of gear ratios belonging thereto, a gear ratio which allows an optimal fuel cost to be realized is selected from said plurality of gear ratios.

12. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

(c) controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said step (b) includes a sub-step in which when a current manual shift range of said transmission gear includes only one gear ratio, said one gear ratio is selected and fixed, and only the intake air flow rate is controlled on the basis of said determined value of the desired drive shaft torque or said accelerator pedal stroke.

13. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of a torque converter having an input shaft coupled to an output shaft of said engine and a flow rate of intake air fed to said engine; and

(c) controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said step (b) includes a sub-step (b-1) in which when said transmission gear is being manipulated for speed change, the intake air flow rate is controlled on the basis of ratio between a detected value of the output shaft rotation number of said transmission gear and the output shaft rotation number of said torque converter.

14. A torque control method for an internal combustion engine according to claim 13,

wherein in said sub-step (b-1), the output shaft rotation number of said torque converter is determined on the basis of a detected value of the output shaft rotation number of said transmission gear and a detected value of an input shaft rotation number of said torque converter.

15. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of a torque converter having an input shaft coupled to an output shaft of said engine and a flow rate of intake air fed to said engine; and

(c) controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said step (b) includes the sub-steps of;

(b-1) determining whether or not speed change operation is being performed on said transmission gear on the basis of a ratio between a detected value of the output shaft rotation number of said transmission gear and the output shaft rotation number of said torque converter; and

(b-2) controlling the intake air flow rate by using a ratio between the detected value of the output shaft rotation number of said transmission gear and the output shaft rotation number said torque converter, when it is determined in said sub-step (b-1) that speed change is being carried out.

16. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least a detected value of accelerator pedal stroke outputted from an accelerator pedal stroke sensor;

(b) determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

(c) controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said step (a) includes a sub-step (a-1) in which when said accelerator pedal stroke sensor is abnormal, the desired drive shaft torque is determined on the basis of a detection signal outputted from detecting means capable of outputting a detection signal equivalent to that of said accelerator pedal stroke sensor.

17. A torque control method for an internal combustion engine according to claim 16,

wherein an acceleration switch outputting said detection signal by detecting whether said accelerator pedal stroke is zero or not is employed as said detecting means.

18. A torque control method for an internal combustion engine according to claim 17,

wherein in said sub-step (a-1), an opening degree of a throttle valve is set to zero when said acceleration switch indicates the accelerator pedal stroke of zero, and if otherwise, the opening degree of said throttle valve is set at a predetermined angle greater than zero degree with said transmission gear being set to a predetermined gear ratio.

19. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

(c) controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said step (b) includes the sub-steps of;

(b-1) selecting the gear ratio at which an optimal fuel cost can be achieved on the basis of at least said determined desired drive shaft torque; and

(b-2) when an absolute value of difference between a fuel consumption at the current gear ratio and a fuel consumption at the gear ratio selected in said sub-step (b-1) exceeds a predetermined value, the current gear ratio is changed over to the gear ratio selected in said sub-step (b-1).

20. A torque control method for an internal combustion engine according to claim 19,

wherein said step (b) includes a sub-step (b-3) in which a current gear ratio is maintained as it is when an absolute value of difference between the fuel consumption at the current gear ratio and the fuel consumption at the gear ratio selected in said sub-step (b-1) is smaller than a predetermined value.

21. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a flow rate of intake air fed to said engine;

(c) selecting a gear ratio allowing an optimal fuel cost to be realized on the basis of at least said desired drive shaft torque as determined, when a transmission gear coupling an output shaft of said engine to a drive shaft of said motor vehicle is shifted upward;

(d) selecting a gear ratio by searching a map prescribing relations among the accelerator pedal strokes, the vehicle speeds or the engine rotation numbers and the gear ratios on the basis of the accelerator pedal stroke and said vehicle speed or said engine rotation number, when said transmission gear is being shifted downward; and

(e) controlling the drive shaft torque of said motor vehicle so that it assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate such that the gear ratio selected in said step (c) or (d) and the intake air flow rate determined in said step (b) can be realized.

22. A torque control method for an internal combustion engine of a motor vehicle, comprising the steps of:

(a) determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

(b) determining on the basis of the determined value of said desired drive shaft torque a flow rate of intake air fed to said engine;

(c) selecting a gear ratio allowing an optimal fuel cost to be realized at least on the basis of said desired drive shaft torque as determined; and

(d) controlling the drive shaft torque of said motor vehicle so that it assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that the gear ratio selected in said step (c) or (d) and the intake air flow rate determined in said step (b) can be realized;

wherein said gear ratio is selected with at least said accelerator pedal stroke as a parameter, when said transmission gear is being shifted downward, while in upward shifting of said transmission gear, said gear ratio is selected at least with the opening degree of the throttle valve being used as a parameter.

23. A torque control apparatus for an internal combustion engine of a motor vehicle, in which a value of a desired drive shaft torque for said motor vehicle is determined on the basis of at least an accelerator pedal stroke for thereby controlling a drive shaft torque of said motor vehicle so as to assume said desired drive shaft torque by controlling a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle on the basis of the value of said desired drive shaft torque as determined,

said apparatus comprising:

decision means for deciding whether or not a torque transfer mechanism coupling an output shaft of said engine and an input shaft of said transmission gear is in a lock-up state in which said input shaft and said output shaft are directly coupled without slip;

first arithmetic means responsive to the decision that said torque transfer mechanism is in said lock-up state, to thereby arithmetically determine a gear ratio of said transmission gear and a flow rate of intake air fed to said engine on the basis of a value of said desired drive shaft torque as determined through a first procedure;

second arithmetic means responsive to the decision that said torque transfer mechanism is not in said lock-up state, to thereby arithmetically determine a gear ratio of said transmission gear and a flow rate of intake air fed to said engine on the basis of a value of said desired drive shaft torque as determined through a second procedure which differs from said first procedure; and

control means for controlling said drive shaft torque of said motor vehicle so that it assumes the value of said desired drive shaft torque by controlling said transmission gear and said engine intake air flow rate such that said gear ratio and said intake air flow rate as determined can be realized.

24. A torque control apparatus for an internal combustion engine according to claim 23,

wherein each of said first and second arithmetic means includes:

means for determining at least one gear ratio at which said determined desired drive shaft torque and a detected value of vehicle speed of said motor vehicle can be realized; and

selecting means for selecting one gear ratio from said determined gear ratios at which an optimal fuel cost can be achieved.

25. A torque control apparatus for an internal combustion engine according to claim 24,

wherein said selecting means includes:

a map prescribing relations at least among values corresponding to the desired drive shaft torques, the gear ratios of said transmission gear and the flow rates of the intake air fed to said engine; and

map search means for searching said map on the basis of said determined desired drive shaft torque to thereby select from said gear ratios a gear ratio at which said optimal fuel cost can be achieved.

26. A torque control apparatus for an internal combustion engine according to claim 25,

each of said first and second arithmetic means includes:

a map prescribing relations at least between values corresponding to the desired drive shaft torques and the intake air flow rates; and

means for searching said map on the basis of the gear ratio selected by said selecting means to thereby determine the intake air flow rate for said engine.

27. A torque control apparatus for an internal combustion engine according to claim 23,

said first arithmetic means includes:

engine rotation number determining means for determining engine rotation numbers for every gear ratio of said transmission gear on the basis of a detected value of said vehicle speed and the gear ratios which said transmission gear has;

engine torque determining means for determining engine torques for every gear ratio of said transmission gear on the basis of said determined desired drive shaft torque and the gear ratios which said transmission gear has;

gear ratio determining means for determining at least one gear ratio on the basis of the engine rotation numbers determined for every gear ratio of said transmission gear and said engine torques; and

gear ratio selecting means for selecting from those determined by said gear ratio determining means a gear ratio at which an optimal fuel cost can be achieved.

28. A torque control apparatus for an internal combustion engine according to claim 27,

wherein said first arithmetic means further includes:

a map prescribing relations existing among the engine rotation numbers, the engine torques and the intake air flow rates; and

intake air flow rate determining means for searching said map on the basis of the gear ratio selected by said gear ratio selecting means and allowing the optimal fuel cost to be achieved, to thereby determine the intake air flow rate.

29. A torque control apparatus for an internal combustion engine according to claim 23,

said second arithmetic means includes:

output shaft rotation number determining means for determining output shaft rotation numbers of said torque transfer mechanism for every gear ratio of said transmission gear on the basis of a detected value of said vehicle speed and the gear ratios which said transmission gear has;

output shaft torque determining means for determining output shaft torques of said torque transfer mechanism for every gear ratio of said transmission gear on the basis of said determined desired drive shaft torque and the gear ratios which said transmission gear has;

engine rotation number/engine torque determining means for determining engine rotation numbers and engine torques for every gear ratio of said transmission gear on the basis of said determined output shaft torque and said output shaft rotation number of said torque transfer mechanism and torque transfer characteristics of said torque transfer mechanism;

gear ratio determining means for determining at least one gear ratio on the basis of the engine rotation number and said engine torque as determined; and

selecting means for selecting from those determined by said gear ratio determining means a gear ratio at which an optimal fuel cost can be realized.

30. A torque control apparatus for an internal combustion engine according to claim 29,

wherein said second arithmetic means further includes:

a map prescribing relations existing among the engine rotation numbers, the engine torques and the intake air flow rates; and

intake air flow rate determining means for searching said map on the basis of the gear ratio selected by said gear ratio selecting means to thereby determine the intake air flow rate.

31. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

means for determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine and at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine;

means for determining a value corresponding to an actual drive shaft torque of said motor vehicle;

means for correcting at least either one of said gear ratio or said intake air flow rate with a deviation of said determined value of the actual drive shaft torque from said determined desired drive shaft torque; and

means for controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as corrected can be realized.

32. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

desired drive shaft torque determining means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

gear ratio/intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

drive shaft torque control means for controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said gear ratio/intake air flow rate determining means includes gear ratio selecting means for selecting a gear ratio which allows an optimal fuel cost to be realized from said plurality of gear ratios when a current manual shift range of said transmission gear includes a plurality of gear ratios belonging thereto.

33. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

gear ratio/intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine and at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

means for controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said gear ratio/intake air flow rate determining means includes;

control means for controlling only the intake air flow rate on the basis of said determined value of the desired drive shaft torque or said accelerator pedal stroke when a current manual shift range of said transmission gear includes only one gear ratio, while said one gear ratio is set fixedly.

34. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

gear ratio/intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of a torque converter having an input shaft coupled to an output shaft of said engine and a flow rate of intake air fed to said engine; and

control means for controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said gear ratio/intake air flow rate determining means includes means for controlling said intake air flow rate on the basis of ratio between a detected value of the output shaft rotation number of said transmission gear and the output shaft rotation number of said torque converter, when said transmission gear is being manipulated for speed change.

35. A torque control apparatus for an internal combustion engine according to claim 34,

wherein said gear ratio/intake air flow rate determining means includes means for determining the output shaft rotation number of said torque converter on the basis of a detected value of the output shaft rotation number of said transmission gear and a detected value of an input shaft rotation number of said torque converter.

36. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

gear ratio/intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of a torque converter having an input shaft to an output shaft of said engine and a flow rate of intake air fed to said engine; and

control means for controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said gear ratio/intake air flow rate determining means includes;

means for determining whether or not speed change operation is being performed on said transmission gear on the basis of a ratio between a detected value of the output shaft rotation number of said transmission gear and the output shaft rotation number of said torque converter; and

means for controlling the intake air flow rate by using a ratio between the detected value of the output shaft rotation number of said transmission gear and the output shaft rotation number said torque converter when it is determined that speed change is being carried out.

37. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

desired drive shaft torque determining means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least a detected value of accelerator pedal stroke outputted from an accelerator pedal stroke sensor;

gear ratio/intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

control means for controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said desired drive shaft torque determining means includes means for determining said desired drive shaft torque on the basis of a detection signal outputted from detecting means capable of outputting a detection signal equivalent to that of said accelerator pedal stroke sensor, when said accelerator pedal stroke sensor is abnormal.

38. A torque control apparatus for an internal combustion engine according to claim 37,

wherein said desired drive shaft torque determining means includes an acceleration switch which outputs said detection signal by detecting whether said accelerator pedal stroke is zero or not.

39. A torque control apparatus for an internal combustion engine according to claim 37,

wherein said desired drive shaft torque determining means includes:

means for setting an opening degree of a throttle valve to zero when said acceleration switch indicates the accelerator pedal stroke of zero; and

means for setting the opening degree of said throttle valve to a predetermined angle greater than zero degree while setting said transmission gear to a predetermined gear ratio.

40. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

gear ratio/intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a gear ratio of a transmission gear coupling an output shaft of said engine to at least a drive shaft of said motor vehicle and a flow rate of intake air fed to said engine; and

means for controlling the drive shaft torque of said motor vehicle so that said drive shaft torque assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that said gear ratio and intake air flow rate as determined can be realized;

wherein said gear ratio/intake air flow rate determining means includes;

gear ratio selecting means for selecting the gear ratio at which an optimal fuel cost can be achieved on the basis of at least said determined desired drive shaft torque;

means for determining an absolute value of difference between a fuel consumption at the current gear ratio and a fuel consumption at the gear ratio selected by said gear ratio selecting means; and

means for changing over the current gear ratio to the gear ratio selected by said gear ratio selecting means when said absolute value is not smaller than a predetermined value.

41. A torque control apparatus for an internal combustion engine according to claim 40,

wherein said gear ratio/intake air flow rate determining means includes means for maintaining a current gear ratio as it is, when the absolute value of difference between the fuel consumption at the current gear ratio and the fuel consumption at the gear ratio selected by said gear ratio selecting means is smaller than a predetermined value.

42. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a flow rate of intake air fed to said engine;

first selecting means for selecting a gear ratio allowing an optimal fuel cost to be realized on the basis of at least said desired drive shaft torque as determined, when a transmission gear coupling an output shaft of said engine to a drive shaft of said motor vehicle is shifted upward;

second selecting means for selecting a gear ratio by searching a map prescribing relations among the accelerator pedal strokes, the vehicle speeds or the engine rotation numbers and the gear ratios on the basis of the accelerator pedal stroke and said vehicle speed or said engine rotation number, when said transmission gear is being shifted downwardly; and

means for controlling the drive shaft torque of said motor vehicle so that it assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that the gear ratio selected by said first or second selecting means and the intake air flow rate determined by said intake air flow rate determining means can be realized.

43. A torque control apparatus for an internal combustion engine of a motor vehicle, comprising:

means for determining a value of a desired drive shaft torque of said motor vehicle on the basis of at least an accelerator pedal stroke;

intake air flow rate determining means for determining on the basis of the determined value of said desired drive shaft torque a flow rate of intake air fed to said engine;

gear ratio selecting means for selecting a gear ratio allowing an optimal fuel cost to be realized on the basis of at least said desired drive shaft torque as determined; and

means for controlling the drive shaft torque of said motor vehicle so that it assumes said desired drive shaft torque by controlling said transmission gear and said intake air flow rate so that the gear ratio selected by said gear ratio selecting means and the intake air flow rate determined by said intake air flow rate determining means can be realized;

wherein said gear ratio selecting means includes;

means for selecting said gear ratio with at least said accelerator pedal stroke as a parameter, when said transmission gear is shifted downward; and

means for selecting said gear ratio at least with the opening degree of the throttle valve being used as a parameter, when said transmission gear is shifted upward.