WO1997004980B1

WO1997004980B1 - Engine speed retardation on transmission upshift

Info

Publication number: WO1997004980B1
Application number: PCT/US1996/012267
Authority: WO
Filing date: 1996-07-25
Publication date: 1997-03-06

Abstract

An improved engine control provides rapid decrease in the output speed of the engine when an upshift of the transmission is being actuated. The system selectively actuates a speed retardation system to decrease the engine output speed to match a desired engine output speed at the next highest gear ratio. In one embodiment, an engine control (38) actuates engine braking to achieve this rapid speed reduction. In other embodiments, an additional load may be placed on the engine (22), such as the actuation of a fan (42). An operator is preferably provided with a shift intent switch (36) that provides an indication to the engine control (38) that an upshift will be actuated. The engine control (38) waits for an indication that the transmission (28) has been moved to neutral. Once this indication is received, the speed retardation system (40) is actuated to rapidly reduce the engine output speed toward a desired value. Most preferably, this feature is incorporated into an engine control system adapted to synchronize the engine output speed to that desired at the next gear ratio, both when the transmission (28) is being upshifted or downshifted. The engine control system allows an operator to achieve a transmission shift without complicated clutching of the transmission.

Claims

AMENDED CLAIMS

[received by the International Bureau on 4 February 1997 (04.02.97);

original claims 7 and 18 cancelled; original claims 1-3, 8-12, 14, 17 and 20 amended;

remaining claims unchanged (5 pages)]

1. A method of operating a vehicle drive including an engine having an output shaft, a transmission connected to be driven by said engine output shaft, an engine control for controlling the output speed of said engine output shaft, a manually operable shift intent switch and a speed retardation system that is controlled by said engine control for rapidly reducing the speed of said engine output shaft, comprising the steps of:

(A) determining that an upshift of said transmission is desirable;

(B) generating an upshift intent signal, using said shift intent switch, that is indicative of a desire to make an upshift of said transmission;

(C) predicting a desired engine speed corresponding to the desired upshift, using said engine control;

(D) actuating said engine speed retardation system when an upshift is being performed to thereby rapidly decrease the output speed of said engine output shaft.

2. A method as recited in Claim 1, wherein said transmission provides a neutral signal to said engine control when said transmission has been moved to neutral, and step (D) is performed only after said neutral signal is received by said engine control.

3. A method as recited in Claim 1, wherein step (C) is performed by predicting a desired engine speed at the next highest speed ratio to achieve a smooth transition to said next highest speed ratio, and wherein said engine control controls actuation of said speed retardation system, and at least one other engine variable to rapidly achieve said desired engine speed.

4. A method as recited in Claim 3, wherein said other variable includes controlling the amount of fuel being delivered to said engine to achieve said desired engine speed.

5. A method as recited in Claim 4, wherein said speed retardation system is an engine braking system for reducing the speed of said engine output shaft.

6. A method as recited in Claim 4, wherein said speed retardation system includes actuating an additional load on said engine.

8. A method as recited in Claim 1 , further comprising the steps of monitoring vehicle conditions, using said engine control and predicting when a transmission upshift is likely.

9. A method of operating a vehicle including an engine having an output shaft, a multi-speed manually operable transmission connected to said output shaft to be driven by said output shaft, a speed retardation system to rapidly decrease the output speed of said engine output shaft, an engine control selectively operable to actuate said speed retardation system, and a manually manipulatable operator shift intent switch, comprising the steps of:

(A) generating an upshift intent signal, using said operator shift intent switch, to indicate that an upshift of said transmission is desirable;

(B) predicting a desired engine speed at the next highest gear, using said engine control responsive to said upshift signal based upon a sensed transmission output speed and the speed ratio at the next highest gear;

(C) generating a neutral signal that is indicative of said transmission being moved out of an engaged gear position into a neutral position;

(D) actuating said engine speed retardation system, using said engine control responsive to said neutral signal, to rapidly decrease said engine output speed to thereby cause said engine output speed to approach said desired engine speed predicted in step (B).

10. A method as recited in Claim 9, further comprising the step of controlling said engine speed by varying the fuel delivered to said engine, using said engine control.

11. A method as recited in Claim 10, further comprising the steps of monitoring actual engine speed, comparing said actual engine speed to said desired engine speed from step (B), and deactivating said speed retardation system as said actual and desired engine speeds approach each other, using said engine control.

12. A vehicle drive comprising:

an engine having an output shaft;

a multi-speed transmission having an input connected to said engine output shaft, and an output for driving a vehicle;

an engine speed retardation system to be selectively actuated to reduce the output speed of said engine output shaft;

a manually operable shift intent switch that is operable to generate an upshift signal indicative that an upshift of said transmission is desired; and

an engine control that is operable to predict a desired engine speed corresponding to a desired transmission upshift responsive to said upshift signal, said engine control further being operable to actuate said speed retardation system upon initiation of an upshift to reduce the speed of said engine output shaft.

13. A vehicle drive as recited in Claim 12, wherein said speed retardation system is the application of an additional load on said engine.

14. A vehicle drive as recited in Claim 12, wherein said engine control is further operable to synchronize said engine speed with said desired engine speed at a next expected gear ratio during a transmission upshift.

15. A vehicle drive as recited in Claim 13, wherein said additional load is an engine braking system that absorbs power from said engine.

16. A vehicle drive as recited in Claim 13, wherein said additional load is the actuation of a fan.

17. A vehicle drive as recited in Claim 12, wherein said engine control will only actuate said speed retardation system after receiving a neutral signal indicating that said transmission has been moved to a neutral position.

19. A vehicle drive as recited in Claim 12, wherein said engine control is operable to predict when an upshift is to be expected, based upon sensed vehicle conditions.

20. A vehicle drive as recited in Claim 12, wherein said engine control is further operable to synchronize said engine speed with said desired engine speed at the next expected speed ratio during a transmission upshift.