Engine speed retardation on transmission upshift

• US 5,830,104 A
• Filed: 05/16/1997
• Issued: 11/03/1998
• Est. Priority Date: 07/27/1995
• Status: Expired due to Term

• Current Assignee: Meritor Transmission Corporation (Meritor, Inc. (Nevada))
• Original Assignee: Meritor Heavy Vehicle Systems, LLC (Meritor, Inc. (Nevada))
• Inventors: Bacon, Edward M., Weisman, Steve M., Desautels, Thomas
• Primary Examiner(s): Marmor, Charles A.
• Assistant Examiner(s): Estremsky, Sherry Lynn
• Application Number:
  US08/857,409
• Time in Patent Office: 536 Days
• Field of Search: 477/107, 477/109, 477/111, 477/122, 477/124
• US Class Current: 477/109
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/11 Stepped gearings
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 30/19 Improvement of gear change, e.g. by synchronisation or smoothing gear shift
• CPC Class Codes: F16H 2306/48 Synchronising of new gear
• CPC Class Codes: F16H 61/0403 Synchronisation before shifting
• CPC Class Codes: F16H 61/682 with interruption of drive
• CPC Class Codes: F16H 63/502 for smoothing gear shifts

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 actuates engine braking to achieve this rapid speed reduction. In other embodiments, an additional load may be placed on the engine, such as the actuation of a fan. An operator is preferably provided with a shift intent switch that provides an indication to the engine control that an upshift will be actuated. The engine control waits for an indication that the transmission has been moved to neutral. Once this indication is received, the speed retardation system 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 is being upshifted or downshifted. The engine control system allows an operator to achieve a transmission shift without complicated clutching of the transmission.

Claims

1. A method of operating a vehicle drive of a vehicle having an engine including an engine output shaft, a transmission that includes a plurality of gear members and that is connected to the engine output shaft by a clutch, an engine control for controlling the output speed of the engine output shaft, a manual shift lever that permits an operator to selectively and manually engage the gear members and a speed retardation system for rapidly reducing the speed of the engine output shaft, comprising the steps of:

A) monitoring the operation of the vehicle with the engine control to thereby predict when a transmission upshift is likely;

B) manually initiating a transmission shift by manually moving the shift lever to disengage a currently engaged gear member without disengaging the clutch;

C) determining whether the transmission shift of step (B) is an upshift; and

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

2. The method of claim 1, further comprising the step of generating a neutral signal indicating that the transmission has been moved to neutral, and wherein step (D) is performed only after the neutral signal is received by the engine control.

3. The method of claim 1, wherein step (A) includes the substep of predicting a desired engine speed at a next highest speed ratio to achieve a smooth transition to the next highest speed ratio, and wherein step (D) includes the step of controlling at least one engine variable, using the engine control, to rapidly achieve the desired engine speed.

4. The method of claim 3, wherein step (D) includes controlling the amount of fuel being delivered to the engine to achieve the desired engine speed.

5. The method of claim 4, wherein the speed retardation system is an engine braking system and step (D) is performed by using the engine braking system to reduce the output speed of the engine output shaft.

6. The method of claim 4, wherein step (D) includes actuating an additional load on said engine.

7. The method of claim 1, wherein an operator is provided with a shift intent switch that is manipulable by an operator to generate an upshift signal when an upshift is desired and wherein step (A) is performed by determining when an upshift signal is generated.

8. The method of claim 1, wherein step (A) includes monitoring vehicle conditions using the engine control.

9. A method of operating a vehicle having an engine including an output shaft, a multi-speed transmission that includes a plurality of gear members and that is connected to be driven by the engine output shaft, a speed retardation system to rapidly decrease the output speed of the engine output shaft, an engine control selectively operable to activate the speed retardation system, a shift lever that permits an operator to selectively and manually engage the gear members and an operator shift intent switch to allow an operator to provide an upshift signal to the engine control, comprising the steps of:

A) manually manipulating the operator shift intent switch to thereby indicate that a transmission upshift is being actuated;

B) sensing an indication of an upshift from the operator switch;

C) predicting a desired engine speed at the next highest gear based upon a sensed transmission output speed and the speed ratio at the next highest gear;

D) manually initiating an upshift of the transmission using the shift lever to manually disengage a currently engaged gear member;

E) providing a signal from the transmission to the engine control once the transmission has been manually moved out of an engaged gear position to a neutral position; and

F) actuating the speed retardation system to rapidly decrease the engine output speed toward the desired engine speed.

10. The method of claim 9, further comprising controlling the engine speed by varying the fuel delivered to the engine, using the engine control.

11. The method of claim 10, wherein step (F) includes using the engine control to perform the substeps of monitoring actual engine speed and comparing the actual engine speed to the desired engine speed and deactivating the speed retardation system as the actual and desired engine speeds approach each other.

12. A vehicle drive, comprising:

an engine having an output shaft;

a multi-speed transmission having an input and an output for driving a vehicle and a plurality of selectively engagable gear members;

a clutch connecting said engine output shaft to said transmission input shaft;

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

a shift lever for manually shifting said gear members into and out of engaged positions; and

an engine control that senses when an upshift in said multi-speed transmission is being actuated and responsively actuates said speed retardation system upon manual initiation of an upshift by manually moving said shift lever to reduce the speed of said engine output shaft.

13. The vehicle drive of claim 12, wherein said speed retardation system includes an additional load that is adapted to be placed on said engine.

14. The vehicle drive of claim 13, wherein said additional load is an engine braking system that absorbs power from said engine.

15. The vehicle drive of claim 13, wherein said additional load is a fan adapted to be driven by said engine.

16. The vehicle drive of claim 12, wherein said transmission includes a sensor that determines when said transmission has been moved to a neutral position and responsively provides a neutral signal to said engine control which begins actuation of said speed retardation system responsive to said neutral signal.

17. The vehicle drive of claim 12, further comprising an operator shift intent switch to provide an upshift signal and wherein said engine control actuates said speed retardation system responsive to said upshift signal.

18. The vehicle drive of claim 12, wherein said engine control is operable to sense vehicle conditions and responsively predict when an upshift is to be expected.

19. The vehicle drive of claim 12, wherein said engine control is operable to predict a desired engine speed at a next expected gear ratio.

20. The vehicle drive of claim 19, wherein said engine control is further operable to synchronize the engine speed with said desired engine speed at the next expected gear ratio during a transmission speed shift.