Control apparatus for an automatic transmission of a vehicle and control method thereof

• US 6,029,107 A
• Filed: 03/03/1997
• Issued: 02/22/2000
• Est. Priority Date: 03/01/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sato, Kazuhiko
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US08/807,991
• Time in Patent Office: 1,086 Days
• Field of Search: 701/65, 701/51, 701/58, 701/60, 701/61, 477/46, 477/97, 477/120, 477/901
• US Class Current: 701/58
• CPC Class Codes: F16H 2059/142 of driving resistance calculated from weight, slope, or the like
• CPC Class Codes: F16H 59/36 Inputs being a function of speed
• CPC Class Codes: F16H 59/40 Output shaft speed
• CPC Class Codes: F16H 59/42 Input shaft speed
• CPC Class Codes: F16H 59/44 dependent on machine speed of the machine, e.g. the vehicle
• CPC Class Codes: F16H 59/66 Road conditions, e.g. slope, slippery
• CPC Class Codes: F16H 61/66259 using electrical or electronical sensing or control means
• CPC Class Codes: Y10S 477/901 Control signal is slope

Abstract

A gear ratio of the automatic transmission is controlled by changing a speed ratio between an input-side rotating member to which the driving force from an engine is transmitted and an output-side rotating member through which the driving force is transmitted to driven wheels. The control apparatus has a vehicle speed detecting part for detecting the speed of the vehicle; a a road gradient estimating part for estimating the gradient of road; a gradient determining part for determining whether or not the road gradient estimated by a road gradient estimating part is beyond a predetermined threshold value; a vehicle speed determining part for determining a target vehicle speed based on the vehicle speed detected by the vehicle speed detecting part, when it is determined by the gradient determining part that the road gradient is beyond the predetermined threshold value; and a control part for controlling the gear ratio so that the vehicle speed can match up to the target vehicle speed determined by the vehicle speed determining part, when it is determined by the gradient determining part that the road gradient is beyond the predetermined threshold value.

Claims

1. A control apparatus for an automatic transmission of a vehicle, in which a gear ratio of the automatic transmission is controlled by changing a speed ratio between an input-side rotating member to which the driving force from an engine is transmitted and an output-side rotating member through which the driving force is transmitted to driven wheels, comprising:

a vehicle speed detecting part for detecting the speed of the vehicle,

road gradient estimating part for estimating a gradient of a road on which the vehicle is running,

a road gradient determining part for determining if the road gradient estimated by a road gradient estimating part is beyond a predetermined threshold value,

a vehicle speed determining part for determining a target vehicle speed based on vehicle speed detected by said vehicle speed detecting part, when it is determined by said gradient determining part that the road gradient is beyond the predetermined threshold value, and

a control part for controlling the gear ratio so that the vehicle speed substantially matches the target vehicle speed determined by said vehicle speed determining part, when it is determined by said gradient determining part that the road gradient is beyond the predetermined threshold value,

wherein said road gradient estimating part further comprises;

a vehicle driving-torque calculating part for calculating the vehicle driving-torque to drive the driven wheels, output from the output-side rotating member,

a running resistance calculating part for obtaining a running resistance torque based on the vehicle speed detected by said vehicle speed detecting part,

an acceleration torque calculating part for obtaining acceleration of the vehicle, and calculating acceleration torque based on the obtained acceleration, and

a gradient calculating part for obtaining a gradient torque, and calculating the road gradient based on the gradient torque obtained by subtracting the running resistance torque calculated by said running resistance calculating part and the acceleration torque calculated by said acceleration torque calculating part from the vehicle driving torque calculated by said vehicle driving-torque calculating part.

2. A control apparatus for an automatic transmission of a vehicle according to claim 1, wherein said vehicle speed determining part determines, as a target speed, a value obtained by multiplying the vehicle speed detected by said vehicle speed detecting part when said gradient determining part determines that the road gradient is beyond the predetermined threshold value by a coefficient corresponding to the vehicle speed.

3. A control apparatus for an automatic transmission of a vehicle according to claim 1, wherein said vehicle speed determining part determines, as a target speed, a value obtained by multiplying the vehicle speed detected by said vehicle speed detecting part when said gradient determining part determines that the road gradient is beyond the predetermined threshold value by a coefficient corresponding to the road gradient estimated by said a road gradient estimating part.

4. A control apparatus for an automatic transmission of a vehicle according to claim 1, wherein said vehicle speed determining part determines, as a target speed. a value obtained by multiplying the vehicle speed detected by said vehicle speed detecting part when said gradient determining part determines that the road gradient is beyond the predetermined threshold value by a coefficient corresponding to the vehicle speed and a coefficient corresponding to the road gradient estimated by said road gradient estimating part.

5. A control apparatus for an automatic transmission of a vehicle according to claim 1, wherein said acceleration torque calculating part is configured and arranged to obtain the acceleration by time-differentiating the vehicle speed detected by said vehicle speed detecting part.

6. A control apparatus for an automatic transmission of a vehicle according to claim 1, wherein the driving force output from the engine is input to the input-side rotating member through a torque converter, wherein said vehicle driving torque calculating part comprises:

an engine speed detector for detecting engine revolutions per minute;

an input rpm detector for detecting rpm of the input-side rotating member;

an output rpm detector for detecting rpm of the output-side rotating member;

a gear ratio calculator for calculating the ratio of the rpm of input-side rotating member to the rpm of the output-side rotating member;

a slip ratio calculator for obtaining the slip ratio by calculating the ratio of the rpm of input-side rotating member to the engine speed;

a torque ratio calculator for obtaining the torque ratio corresponding to the calculated slip ratio by using a map which represents a relationship between a predetermined slip ratio of the torque converter and a torque ratio of a pump torque and a turbine torque;

a pump capacity coefficient calculator for obtaining a coefficient of pump capacity corresponding to the calculated slip ratio by using a map which represents a relationship between the predetermined slip ratio of the torque converter and the pump capacity coefficient, and wherein a driving force for vehicle wheels is calculated on the basis of the engine speed, the gear ratio, the torque ratio and the pump capacity coefficient.

7. A control method of an automatic transmission of a vehicle, in which a gear ratio of the automatic transmission is controlled by changing a speed ratio between an input-side rotating member to which the driving force from an engine is transmitted and an output-side rotating member through which the driving force is transmitted to driven wheels, comprising the steps of:

detecting speed of the vehicle, and a vehicle driving torque for driving driven wheels, output from the output-side rotating member;

obtaining a gradient torque by subtracting acceleration torque and running resistance torque obtained on the basis of the detected vehicle speed from the detected vehicle driving torque, and estimating a gradient of the road on which the vehicle is running on the basis of the gradient torque;

determining if the estimated road gradient is beyond a predetermined threshold value,

determining a target vehicle speed on the basis of the vehicle speed when it is determined that the estimated road gradient is beyond the predetermined threshold value, and

controlling the gear ratio so that the vehicle speed substantially matches the target vehicle speed determined when the estimated road gradient is beyond the predetermined threshold value.

8. A control apparatus for an automatic transmission of a vehicle, in which the gear ratio of a non-step transmission installed in the vehicle is controlled according to a running state of the vehicle, comprising:

a storing means for storing corresponding data in which a target gear ratio of the non-step transmission is uniquely identified by a road gradient;

a gradient estimating means for estimating the road gradient on which the vehicle is running by using the running state of the vehicle; and

a determining means for determining that the vehicle is running on a slope when the estimated road gradient is within a predetermined range;

wherein a target gear ratio of the non-step transmission corresponding to the estimated road gradient due to the corresponding data stored in said storing means is used to control the gear ratio when said determining means determines that the vehicle is running on a slope.

9. A control apparatus for an automatic transmission of a vehicle according to claim 8, further comprising detecting means for calculating acceleration torque of the vehicle and running resistance torque thereof by vehicle weight and a vehicle speed detected during a run.

10. A control apparatus for an automatic transmission of a vehicle according to claim 8, further comprising detecting means for calculating a torque of an output shaft of the non-step transmission by using the gear ratio, the opening of the accelerator and the engine speed detected during a run.

11. A control method for an automatic transmission of a vehicle, in which the gear ratio of a non-step transmission installed in the vehicle is controlled according to a running state of the vehicle, comprising the steps of:

detecting acceleration torque, running resistance torque and an output shaft torque of the non-step transmission;

estimating a gradient of the road which the vehicle is running by using the running state of the vehicle detected at said detecting step;

determining that the vehicle is running on a slope when the estimated road gradient is within a predetermined range; and

controlling the gear ratio of the non-step transmission so that the gear ratio of the non-step transmission substantially matches a target gear ratio corresponding to the estimated road gradient due to the corresponding data by which the target gear ratio is uniquely identified by the road gradient, when said determining step determines that the vehicle is running on a slope.

12. A control apparatus for an automatic transmission of a vehicle, in which the gear ratio of a non-step transmission installed in the vehicle is controlled according to a predetermined gear schedule using a running state of the vehicle, comprising:

apparatus for detecting acceleration torque, running resistance torque and a torque of an output shaft of the non-step transmission as the running state of the vehicle;

apparatus for storing corresponding data in which an amount of correction of a target gear ratio of the non-step transmission is uniquely identified by a road gradient;

apparatus for estimating the gradient of the road on which the vehicle is running by using the running state; and

apparatus for correcting the gear ratio of the non-step transmission defined according to the predetermined gear schedule by using a correction value for the non-step transmission corresponding to the road gradient estimated due to the stored corresponding data,

wherein the gear ratio of the non-step transmission is controlled so that the gear ratio substantially matches a corrected target gear ratio when the vehicle is determined to be running on a slope.

13. A control apparatus for an automatic transmission of a vehicle according to claim 12, wherein said detecting apparatus calculates the acceleration torque and the running resistance torque by using vehicle weight and vehicle speed detected during a run.

14. A control apparatus for an automatic transmission of a vehicle according to claim 12, wherein said detecting apparatus calculates a torque of an output shaft of the non-step transmission by using the gear ratio of the non-step transmission, an accelerator opening and engine speed, detected during a run.

15. A control method for an automatic transmission of a vehicle, in which the gear ratio of a non-step transmission installed in the vehicle is controlled according to a predetermined gear schedule using a running state of the vehicle, comprising the steps of:

detecting acceleration torque, running resistance torque and a torque of an output shaft of the non-step transmission as the running state;

estimating a gradient of the road on which the vehicle is running by using the running state;

correcting the gear ratio of the non-step transmission defined according to the predetermined gear schedule with a correction value for the non-step transmission corresponding to the road gradient estimated due to corresponding stored data, and

controlling the gear ratio of the non-step transmission so that the gear ratio of the non-step transmission substantially matches the corrected target gear ratio when the vehicle is determined to be running on a slope.