System for automatically controlling vehicle speed to desired cruise speed whose control function is inhibited when system for controlling a vehicular traction operates and method therefor

• US 4,951,208 A
• Filed: 10/24/1988
• Issued: 08/21/1990
• Est. Priority Date: 10/26/1987
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Etoh, Yoshiyuki
• Primary Examiner(s): Black, Thomas G.
• Application Number:
  US07/261,154
• Time in Patent Office: 666 Days
• Field of Search: 364/426.01, 364/426.02, 364/426.03, 364/426.04, 364/424.01, 180/197, 180/170, 180/176, 123/361, 123/352, 324/160, 324/161
• US Class Current: 701/97
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00

Abstract

A system and method for automatically controlling a vehicle speed to a desired cruise speed are disclosed in which an opening angle of a first throttle valve is adjusted so that the vehicle speed coincides with a target vehicle speed at which the vehicle cruises. The cruise control for the vehicle speed through the first throttle valve is inhibited when an occurrence of a slip on a drive wheel is detected and a traction control by means of a traction controlling system such that a driving force of the vehicle is reduced through a second throttle valve disposed in series with the first throttle valve in an engine intake air passage is executed so that an effective traction control can be achieved without interference of both systems when the vehicle enters on a road surface having a very low friction coefficient.

Claims

1. A system for a vehicle, comprising:

(a) first means for detecting a vehicle speed;

(b) second means through which the current vehicle speed is set as a cruise speed at which a vehicle driver desires to cruise;

(c) third means responsive to the set of the cruise speed through the second means for outputting a speed control command so that the vehicle speed coincides with the set cruise speed;

(d) fourth means for adjusting a driving force of the vehicle through a first engine driving force adjusting mechanism according to the speed command from the third means;

(e) fifth means for detecting whether a slip on a drive wheel of the vehicle occurs;

(f) sixth means for outputting a speed reduction command when the occurrence of slip is detected by the fifth means;

(g) seventh means for reducing the driving force through a second engine driving force adjusting mechanism according to the speed reduction command derived from the sixth means; and

(h) eighth means for inhibiting the output of the speed control command to the fourth means when the occurrence of the slip is detected by the fifth means.

2. A system as set forth in claim 1, wherein said first engine driving force adjusting mechanism comprises a first throttle valve installed in an intake air passage of a vehicular engine, and wherein the opening angle of said first throttle valve is variable.

3. A system as set forth in claim 1, wherein said second engine driving force adjusting mechanism comprises a second throttle valve installed in an intake air passage of a vehicular engine, and wherein the opening angle of said second throttle valve is variable.

4. A system as set forth in claim 1, wherein said first engine driving the force adjusting mechanism comprises a first throttle valve installed in an intake air passage of a vehicular engine, and said second engine driving force adjusting mechanism comprises a second throttle valve installed in an intake air passage of said vehicular engine in series with said first throttle valve, and wherein the opening angles of said first and second throttle valves are variable.

5. A system for a vehicle, comprising:

(a) first means for detecting a speed of a vehicular drive wheel;

(b) second means through which the current drive wheel speed is set as a cruise speed at which a vehicle driver desires to cruise;

(c) third means, including a first actuator, responsive to the set of the cruise speed through the second means for receiving the drive wheel speed information from the first means and for outputting a first actuation command to the first actuator so that the drive wheel speed coincides with the set cruise speed, the first actuator actuating a first vehicle driving force adjusting mechanism;

(d) fourth means for detecting a variable determining the vehicle driving force from the first driving force adjusting mechanism;

(e) fifth means for detecting a vehicle body speed;

(f) sixth means, including a second actuator, for receiving the drive wheel speed information from the first means, the variable information from the fourth means, and the vehicle body speed information from the fifth means, and for outputting a second actuation command to the second actuator so as to reduce the driving force when a difference between the drive wheel speed and vehicle body speed exceeds a predetermined value, the second actuator actuating a second vehicular driving force adjusting mechanism, the sixth means outputting an interrupt signal to the third means so as to cancel the output of the first actuation command signal to the third means when outputting the second actuation signal.

6. A system as set forth in claim 5, wherein the sixth means calculates a difference between the drive wheel speed and vehicle body speed, compares the difference with the predetermined value so as to detect the occurrence of a slip on the drive wheel, and calculates a variable determining the reduction of speed through the second driving force adjusting mechanism on the basis of the speed difference, a difference between the current speed difference and a previous speed difference one control period before.

7. A system as set forth in claim 6, wherein the sixth means calculates the variable θ

₂ in the following equation;

space="preserve" listing-type="equation">θ

.sub.2 =90°

-(G.sub.p ×

delta V+G.sub.D ×

delta.sup.2 V), in

the equation G_p denotes a proportional gain, G_D denotes a differential gain, delta V denotes the speed difference, and delta² V is expressed as delta V-delta VOLD, and delta VOLD denotes delta V one control period before.

8. A system as set forth in claim 7, wherein the variable of the second driving force adjusting mechanism is set to 90°

when no occurrence of slip is detected by the sixth means.

10. A system as set forth in claim 6, wherein the output of the first actuation command signal from the third means to the first actuator is carried out after a predetermined delay upon the detection of the difference of speed below the predetermined value after the sixth means outputs the second actuation command to the second actuator so as to reduce the drive force.

11. A system as set forth in claim 10, wherein the predetermined delay is 10 seconds.

12. A system as set forth in claim 5, wherein the predetermined value is 5 Km/h.

13. A system as set forth in claim 5, wherein the third and sixth means are constituted by a single microcomputer except the first and second actuators.

9. A system as set forth in claim 9, wherein the first and second driving force adjusting mechanisms are first and second throttle valves installed in an intake air passage of a vehicular engine, opening angles of both throttle valves being the variables.

14. A method for controlling a driving force of a vehicle, comprising the steps of:

(a) detecting a vehicle speed;

(b) providing switch means through which the current vehicle speed is set as a cruise speed at which a vehicle driver desires to cruise and setting the cruise speed through the switch means;

(c) outputting a speed control command when the cruise speed is set through the switch means in the step (b) so that the vehicle speed coincides with the set cruise speed;

(d) adjusting a driving force of the vehicle through a first engine driving force adjusting mechanism according to the speed control command outputted in the step (c);

(e) detecting occurrence of a slip on a drive wheel of the vehicle;

(g) outputting a speed reduction command when the occurrence of the slip is detected in the step (e);

(g) reducing the driving force through a second engine driving force adjusting mechanism according to the speed reduction command outputted in the step (f); and

(h) inhibiting the output of the speed control command in the step (d) when the occurrence of the slip is detected in the step (e).

15. A method as set forth in claim 14, wherein said step of adjusting a driving force of the vehicle through said first engine driving force adjusting mechanism comprises adjusting the angle of a first throttle valve installed in an intake air passage of a vehicular engine.

16. A method as set forth in claim 14, wherein said step of adjusting a driving force of the vehicle through said second engine driving force adjusting mechanism comprises adjusting the angle of a second throttle valve installed in an intake air passage of a vehicular engine.

17. A method as set forth in claim 14, wherein said step of adjusting a driving force of the vehicle through said first engine driving force adjusting mechanism comprises adjusting the angle of a first throttle valve installed in an intake air passage of a vehicular engine, and said step of adjusting a driving force through said second engine driving force adjusting mechanism comprises adjusting the angle of a second throttle valve installed in an intake air passage of said vehicular engine in series with said first valve.