Method and apparatus for control of engine compression brakes before during and after an electronically controlled gear shift

Abstract

An engine compression brake control device is disclosed. The control device is electronic and prevents activation of the engine compression brakes during operating states wherein undesirable conditions will result if the engine brakes are active. The electronic control device monitors various conditions and activates the engine brakes only if all of the following conditions are simultaneously detected: a valid gear ratio is detected; the driver has requested or enabled engine compression brake operation; the clutch pedal is out; the throttle is at a minimum engine speed position; and the electronic controller is not presently attempting to execute an electronically controlled final drive gear shift.

What is claimed is: 
     
       1. A device for controlling activation of an engine compression brake in association with a vehicle drive train including an engine, a throttle control connected to the engine, a manual/automatic transmission having a plurality of selectable gear reduction ratios, and a manual clutch situated between the engine and the transmission, said device comprising: . .means for determining a valid gear ratio corresponding to one of the gear reduction ratios of the transmission and producing a valid gear ratio signal in response thereto;.!.   means for sensing an automatic shift state of the transmission corresponding to an active shift time period and producing a shift not active signal when said automatic shift state is not active;   means for sensing a closed throttle position for the throttle control and producing a throttle closed signal in response thereto;   means for sensing engagement of said clutch and producing a clutch engaged signal in response thereto;   means for enabling engine compression brake operation and producing a brake enable signal in response thereto; and   means for activating the compression brake in response to the concurrent presence of . .said valid gear ratio signal,.!. said throttle closed signal, said clutch engaged signal, said shift not active signal and said brake enable signal.   
     
     
       2. The device of claim 1 including: means for sensing vehicle speed and producing a speed signal corresponding to vehicle speed; . .and.!.   means for sensing engine speed and producing an RPM signal corresponding to engine speed, .Iadd.and .Iaddend.   . .wherein said.!. means for determining a valid gear ratio . .compares.!. .Iadd.by comparing .Iaddend.said RPM signal with said speed signal to produce a speed ratio signal, said means for determining producing said valid gear ratio signal when said speed ratio signal is within one of a plurality of predetermined ratio ranges corresponding to the gear reduction ratios of the transmission.Iadd.;   wherein production of said shift not active signal after said automatic shift state is conditioned upon the presence of said valid gear ratio.Iaddend..   
     
     
       3. The device of claim 2 wherein said means for sensing vehicle speed and said means for sensing engine speed are magnetic sensors. 
     
     
       4. The device of claim 3 wherein said means for sensing a closed throttle, said means for enabling engine compression brake operation and said means for sensing engagement of said clutch are switches. 
     
     
       5. The device of claim 4 wherein said means for sensing an automatic shift state and said means for activating the compression brake are components of an engine control module including a microcomputer, RAM, ROM, analog I/O and digital I/O. 
     
     
       6. A method for controlling activation of an engine compression brake in association with a vehicle drive train including an engine, a throttle control connected to the engine, a manual/automatic transmission having a plurality of selectable gear reduction ratios, and a manual clutch situated between the engine and the transmission, said method comprising the steps of: . .detecting a valid gear ratio state of the transmission;.!.   detecting a non-shift state of the transmission corresponding to time periods between automatically controlled shifting transitions between two of the selectable gear reduction ratios;   detecting a closed throttle position for the throttle control;   detecting engagement of the clutch;   detecting an operator request for engine compression brake operation; and   enabling operation of the compression brakes in response to detection of said non-shift state, said closed throttle position, said engagement of the clutch. .,.!. .Iadd.and .Iaddend.said operator request. ., and said valid gear ratio.!..   
     
     
       7. A device for controlling activation of an engine compression brake in association with a vehicle drive train including an engine, a throttle control connected to the engine, a manual/automatic transmission having a plurality of manually selectable gear ratios and at least two automatically selectable gear ratios, and a manual clutch situated between the engine and the transmission, said device comprising: an electronic cruise control device for fueling the engine and automatically shifting gears of the transmission in response to an operator cruise control request, said cruise control device producing a shift not active signal when not automatically changing gear ratios of the transmission;   . .means for determining a valid gear ratio corresponding to one of the gear ratios of the transmission and producing a valid gear ratio signal in response thereto;.!.   means for sensing a substantially closed throttle position for the throttle control and producing a throttle closed signal in response thereto;   means for sensing engagement of said clutch and producing a clutch engaged signal in response thereto;   means for enabling engine compression brake operation and producing a brake enable signal in response thereto; and   electronic control circuit means for activating the compression brake in response to the concurrent presence of . .said valid gear ratio signal,.!. said throttle closed signal, said clutch engaged signal, said shift not active signal and said brake enable signal.   
     
     
       8. The device of claim 7 wherein said transmission includes an electromechanical actuator for automatically changing gear ratios and said electronic cruise control device provides a shift signal to said electromechanical actuator to shift from a low gear to a high gear ratio. 
     
     
       9. The device of claim 7 wherein said transmission includes a first and a second electromechanical actuator, wherein said electronic cruise control device provides a first signal to said first actuator to actuate a first automatically selectable gear ratio, said cruise control device also providing a second signal to said second actuator to actuate a second automatically selectable gear ratio.