Main pump to auxiliary pump hand-off strategy for maintaining hydraulic pressure in hybrid transmission
View Patent ↗A method and system of providing hydraulic pressure during a transition from gas-powered engine operation to electric motor operation in a hybrid electric vehicle. During the transition, main pressure arising from operation of a gas-powered engine with a main pump is matched with auxiliary pressure arising from operation of a battery-powered electric motor with an auxiliary pump. After matching the main and auxiliary pressures, the auxiliary pressure is boosted to an operational pressure in response to a triggering event.
1. A method of providing hydraulic pressure during a transition from gas-powered engine operation to electric motor operation in a hybrid electric vehicle, the method comprising:
operating a gas-powered engine with a main pump and a battery-powered electric motor with an auxiliary pump by substantially matching, for a period of time until a triggering event occurs, a main pressure arising from operation of the main pump and an auxiliary pressure arising from operation of the auxiliary pump before the transition from gas-powered engine operation to electric motor operation has completed; and
boosting the auxiliary pressure to an operational pressure in response to the triggering event.
2. The method of claim 1 , further comprising monitoring a speed of the auxiliary pump while the main pressure and auxiliary pressure are matched.
3. The method of claim 2 , wherein monitoring a speed of the auxiliary pump further comprises monitoring a filtered speed of the auxiliary pump.
4. The method of claim 3 , wherein the triggering event is when the filtered speed of the auxiliary pump is within a predetermined range of a desired speed.
5. The method of claim 4 , further comprising keeping the main pressure constant while the auxiliary pressure is boosted to the operational pressure.
6. The method of claim 5 , further comprising decreasing the main pressure once the auxiliary pressure is at the operational pressure.
7. The method of claim 1 , wherein the triggering event is when a speed of the gas-powered engine falls below a predetermined low-speed threshold.
8. The method of claim 1 , wherein the triggering event comprises whichever of a first and second triggering event occurs first.
9. The method of claim 8 , wherein the first triggering event is when a filtered speed of the auxiliary pump is within a predetermined range of a desired speed.
10. The method of claim 8 , wherein the second triggering event is when a speed of the gas-powered engine falls below a predetermined low-speed threshold.
11. An auxiliary pump system in a hybrid electric vehicle, the system comprising:
an auxiliary pump with an associated electric motor, the auxiliary pump being configured to maintain hydraulic pressurization in the hybrid electric vehicle's transmission system during a transition from operation of the hybrid electric vehicle's gas-powered engine with associated main pump to the hybrid electric vehicle's electric motor with associated auxiliary pump; and
a processor configured to control the operation of the auxiliary pump and the gas-powered engine during a transition between vehicle operation in a gas-powered engine mode and vehicle operation in an electric motor mode, said processor control comprising:
substantially matching, for a period of time until a triggering event occurs, a main pressure arising from operation of the main pump and an auxiliary pressure arising from operation of the auxiliary pump before the transition from gas-powered engine operation to electric motor operation has completed; and
boosting the auxiliary pressure to an operational pressure in response to the triggering event.
12. The auxiliary pump system of claim 11 , wherein the processor is further configured to monitor a speed of the auxiliary pump while the main pressure and auxiliary pressure are matched.
13. The auxiliary pump system of claim 12 , wherein the processor is further configured to monitor a filtered speed of the auxiliary pump.
14. The auxiliary pump system of claim 13 , wherein the triggering event is when the filtered speed of the auxiliary pump is within a predetermined range of a desired speed.
15. The auxiliary pump system of claim 14 , wherein the processor is further configured to keep the main pressure constant while the auxiliary pressure is boosted to the operational pressure.
16. The auxiliary pump system of claim 15 , wherein the processor is further configured to decrease the main pressure once the auxiliary pressure is at the operational pressure.
17. The auxiliary pump system of claim 11 , wherein the triggering event is when a speed of the gas-powered engine falls below a predetermined low-speed threshold.
18. The auxiliary pump system of claim 11 , wherein the triggering event comprises whichever of a first and second triggering event occurs first.
19. The auxiliary pump system of claim 18 , wherein the first triggering event is when a filtered speed of the auxiliary pump is within a predetermined range of a desired speed.
20. The auxiliary pump system of claim 18 , wherein the second triggering event is when a speed of the gas-powered engine falls below a predetermined low-speed threshold.