Patent EA-003849-B1 (EA)
Title: Method and engine speed control system for improved shifting
Inventor: MEYER DUANE FREDERICK
IPC: B60W10/113
Filed: 2000-11-25
Abstract: 1. Method for improved shifting in a vehicle having a governor controlled engine (10) which drives a power shift transmission (12), the power shift transmission (12) having a gear box (18) which is operated by a set of pressure operated clutches (20) which are controlled by a corresponding set of solenoid operated shift control valves (22) which are controlled by an electronic vehicle control unit (VCU) in response to the shift command signals generated by an operator controlled shift control lever mechanism (24), the engine (10) being controlled by an electronic engine control unit (ECU) which receives a speed command signal (SC) from the VCU, wherein comprising: momentarily modifying a magnitude of the speed command signal (SC) during a shift of the power shift transmission (12); and during said shift, abruptly modifying the magnitude of the speed command signal (SC) from a first magnitude to a second magnitude then gradually returning the speed command signal (SC) back to said first magnitude upon completion of said shift. 2. The method of claim 1, wherein: the solenoid operated shift control valves (22) operate to vary pressures applied to the pressure operated clutches (20); and the magnitude of the speed command signal (SC) is momentarily modified in coordination with the variations of said clutch pressure. 3. The method according claim 1 or 2, wherein: during an upshift of the power shift transmission (12) the magnitude of the speed command signal (SC) is reduced. 4. The method of claim 3, wherein: the magnitude of the speed command signal (SC) is momentarily reduced during said upshift. 5. The method of claim 3 or 4, wherein: during said upshift, the magnitude of the speed command signal (SC) is abruptly reduced and then gradually increased back to the first magnitude prior to said upshift. 6. The method according one of the claims 1 to 5, wherein: during a downshift of the power shift transmission (12), the magnitude of the speed command signal (SC) is increased. 7. The method of claim 6, wherein: the magnitude of the speed command signal (SC) is momentarily increased during said downshift. 8. The method of claim 6 or 7, wherein: during said downshift, the magnitude of the speed command signal (SC) is abruptly increased and then gradually decreased back to the first magnitude prior to said downshift. 9. The method according one of the claims 1 to 8, wherein: the speed command signal (SC) is modified to a value which produces a modified engine speed corresponding to a change in a gear ratio resulting from the shift. 10. The method of claim 9, wherein: during an upshift, the speed command signal (SC) is reduced to a value which produces alower engine speed corresponding to a change in a gear ratioresulting from the upshift. 11. The method of claim 9 or 10, wherein: during a downshift, the speed command signal (SC) is increased to a value which produces a higher engine speed corresponding to a change in a gear ratioresulting from the downshift. 12. A control system for a vehicle having a governor controlled engine (10) which drives a power shift transmission (12), the power shift transmission (12) having a gear box which is operated by a set of pressure operated clutches (20) which are controlled by a corresponding set of solenoid operated shift control valves (22) which are controlled by an electronic vehicle control unit (VCU) in response to the shift command signals generated by an operator controlled shift control lever mechanism (24), the engine (10) being controlled by an electronic engine control unit (ECU) which receives a speed command signal (SC) from the VCU, comprising: a speed command modifier for momentarily modifying a magnitude of the speed command signal (SC) during a shift of the power shift transmission(12), and during said shift, the speed command modifier abruptly modifies the magnitude of the speed command signal (SC) from a first magnitude to a second magnitude, and then gradually returns the magnitude of the speed command signal (SC) back to the first magnitude upon completion of said shift. 13. The control system of claim 12, wherein: the solenoid operated shift control valves (22) operate to vary pressures applied to the pressure operated clutches (20); and the magnitude of the speed command signal (SC) is momentarily modified in coordination with the variations of said clutch pressure. 14. The control system according claim 12 or 13, wherein: the speed command modifier comprises means for modifying the magnitude of the speed command signal (SC) according the method of one of the claims 3 to 11.