METHOD AND APPARATUS TO CONTROL OPERATION OF A HYDRAULIC PUMP FOR AN ELECTRO-MECHANICAL TRANSMISSION

• US 20090112423A1
• Filed: 10/13/2008
• Published: 04/30/2009
• Est. Priority Date: 10/29/2007
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG, Daimler AG (Mercedes-Benz Group AG), Chrysler Group LLC (Stellantis NV)
• Original Assignee: BMW AG (Bayerische Motoren Werke AG), GM Global Technology Operations Incorporated (General Motors Company), Daimler AG (Mercedes-Benz Group AG), Chrysler LLC (Stellantis NV)
• Inventors: FOSTER, MICHAEL D., NAQVI, ALI K., TRYON, ERIC S., SAH, JY-JEN F.
• Granted Patent: US 8,170,762 B2
• Time in Patent Office: Days
• US Class Current: 701/60
• CPC Class Codes: F16H 2037/102 the input or output shaft of the transmission is connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/104 Power split variators with one end of the CVT connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/106 with switching means to provide two variator modes or ranges
• CPC Class Codes: F16H 2312/14 Going to, or coming from standby operation, e.g. for engine start-stop operation at traffic lights
• CPC Class Codes: F16H 3/727 with at least two dynamo electric machines for creating an electric power path inside the gearing, e.g. using generator and motor for a variable power torque path special adapted for a hybrid electric vehicle B60K6/20
• CPC Class Codes: F16H 61/0031 using auxiliary pumps, e.g. pump driven by a different power source than the engine

Abstract

A method for controlling a hydraulic flow within a powertrain comprising an electromechanical transmission mechanically-operatively coupled to an engine adapted to selectively transmit power to an output, wherein the transmission utilizes a hydraulic control system serving a number of hydraulic oil consuming functions includes monitoring minimum hydraulic pressure requirements for each of the functions, determining a requested hydraulic pressure based upon the monitoring minimum hydraulic pressure requirements and physical limits of the hydraulic control system including a maximum pressure, determining a desired flow utilizing a hydraulic control system flow model based upon the requested hydraulic pressure, and utilizing the desired flow to control an auxiliary hydraulic pump.

Claims

1. Method for controlling a hydraulic flow within a powertrain comprising an electromechanical transmission mechanically-operatively coupled to an engine adapted to selectively transmit power to an output, wherein said transmission utilizes a hydraulic control system serving a number of hydraulic oil consuming functions, said method comprising:

monitoring minimum hydraulic pressure requirements for each of said functions;

determining a requested hydraulic pressure based upon said monitoring minimum hydraulic pressure requirements and physical limits of said hydraulic control system including a maximum pressure;

determining a desired flow utilizing a hydraulic control system flow model based upon said requested hydraulic pressure; and

utilizing said desired flow to control an auxiliary hydraulic pump.

2. The method of claim 1, wherein determining said requested hydraulic pressure based upon said monitoring minimum hydraulic pressure requirements and said physical limits of said hydraulic control system comprises:

selecting a desired hydraulic pressure from a maximum of said minimum hydraulic pressure requirements; and

utilizing said desired hydraulic pressure as said requested hydraulic pressure unless said desired hydraulic pressure is outside said physical limits.

3. The method of claim 1, further comprising:

monitoring a speed of said engine;

determining a main hydraulic flow of a directly driven main hydraulic pump based upon said speed of said engine;

predicting said main hydraulic flow decreasing below said desired flow by more than a transition threshold; and

commanding an auxiliary hydraulic pump primer based upon said predicting.

4. The method of claim 3, wherein predicting said main hydraulic flow falling below said desired flow by more than said transition threshold is based upon a pending engine stop event.

5. The method of claim 4, wherein commanding an auxiliary hydraulic pump primer is initiated a calibrated lead time before initiation of said pending stop engine event.

6. The method of claim 4,

wherein said transmission is further mechanically-operatively coupled to an electric machine, and

wherein said pending engine stop event is part of a hybrid control strategy.

7. The method of claim 4,

wherein said transmission is further mechanically-operatively coupled to a plurality of electric machines, and

wherein said pending engine stop event is part of a hybrid control strategy.

8. The method of claim 3,

wherein said powertrain is in a motor vehicle, and

wherein said predicting said main hydraulic flow falling below said desired flow by more than said transition threshold is based upon a road sensing device monitoring conditions in front of the vehicle.

9. The method of claim 3, wherein said predicting said main hydraulic flow falling below said desired flow by more than said transition threshold is based upon data from a 3D map device.

10. The method of claim 1, further comprising:

monitoring a speed of said engine; and

determining a main hydraulic flow of a directly driven main hydraulic pump based upon said speed of said engine;

wherein said utilizing said desired flow to control said auxiliary hydraulic pump comprises, when said main hydraulic flow decreases below said desired flow by more than a transition threshold, commanding said desired flow from said auxiliary hydraulic pump.

11. The method of claim 10, wherein commanding said desired flow from said auxiliary hydraulic pump includes when said main hydraulic flow increases more than a second transition threshold above said desired flow, commanding said auxiliary hydraulic pump to stop.

12. The method of claim 1, wherein monitoring said minimum hydraulic pressure requirements comprises:

monitoring operation of hydraulically actuated clutches within said transmission;

monitoring operation of an active electric machine cooling circuit;

monitoring requirements of a base cooling electric machine cooling circuit; and

monitoring requirements of a lubrication circuit.

13. The method of claim 1, further comprising monitoring an auxiliary hydraulic pump availability, wherein said utilizing said desired flow to control said auxiliary hydraulic pump includes modulating said control based upon said auxiliary hydraulic pump availability.

14. Method for controlling a powertrain comprising an electromechanical transmission mechanically-operatively coupled to an internal combustion engine and first and second electric machines adapted to selectively transmit mechanical power to an output, said method comprising:

monitoring commands to said engine to transition between an engine stopped state and an engine running state;

modeling a desired flow within a hydraulic control system based upon pressure requirements of said transmission and known flow behavior within said hydraulic control system; and

selectively controlling operation an auxiliary hydraulic pump based upon said desired flow during said transitioning of said engine between said engine stopped state and said engine running state.

15. The method of claim 14, wherein said selectively controlling operation said auxiliary hydraulic pump based upon said desired flow comprises bringing said auxiliary hydraulic pump to a speed to produce said desired flow in anticipation of said transitioning of said engine.

16. Apparatus for controlling a hydraulic flow within a powertrain comprising an electromechanical transmission mechanically-operatively coupled to an engine adapted to selectively transmit power to an output, wherein said transmission utilizes a hydraulic control system serving a number of hydraulic oil consuming functions, said apparatus comprising:

an auxiliary hydraulic pump in fluid communication with said hydraulic control system;

an auxiliary flow determination module, including logic to

monitor a requested pressure determined based upon minimum pressure requirements of said hydraulic oil consuming functions and physical limits of said hydraulic control system, and

determine a desired flow based upon said requested pressure and known behavior of said hydraulic control system; and

an auxiliary pump controller in signal communication with said auxiliary flow determination module and issuing command signals to said auxiliary hydraulic pump, including logic to

monitor said desired flow,

monitor a main flow from a main hydraulic pump, and

issue commands to said auxiliary hydraulic pump based upon said desired flow and said main flow.

17. The apparatus or claim 16, wherein said auxiliary pump controller further includes logic to:

monitor an estimated maximum hydraulic flow that said auxiliary hydraulic pump is capable of providing; and

monitor an auxiliary pump availability;

wherein said logic to issue commands to said auxiliary hydraulic pump is further based upon said estimated maximum hydraulic flow and said auxiliary pump availability.

18. The apparatus of claim 16, wherein said auxiliary pump controller further includes logic to monitor an auxiliary pump primer signal including instructions to command said auxiliary hydraulic pump to an operational speed based upon a pending engine stop event.

19. The apparatus of claim 16,

wherein said auxiliary pump controller further includes logic to determine if said main flow is below said desired flow by more than a transition threshold, and

wherein said logic to issue commands to said auxiliary hydraulic pump is based upon said determination.