Hybrid Vehicle Powertrain with a Multiple-Ratio Power Transmission Mechanism

• US 20070270277A1
• Filed: 08/06/2007
• Published: 11/22/2007
• Est. Priority Date: 09/10/2003
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Colvin, Dan, Kraska, Marvin, Ortmann, Walt, Fozo, Bob, Encelewski, Michael
• Granted Patent: US 7,331,899 B2
• Time in Patent Office: Days
• US Class Current: 477/5
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/0657 Engine torque
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/16 Ratio selector position
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: F16H 2306/42 Changing the input torque to the transmission
• CPC Class Codes: F16H 61/0437 by using electrical signals F16H61/0403 and F16H61/061 take precedence
• CPC Class Codes: F16H 61/686 with orbital gears
• CPC Class Codes: F16H 63/502 : for smoothing gear shifts
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility

Abstract

A control method and system for a hybrid vehicle powertrain with an electric motor in a power flow path between an internal combustion engine and a multiple-ratio geared transmission. Motor torque, which is added to engine torque to obtain an effective transmission input torque, is modulated to achieve smooth power-on upshifts and coasting downshifts.

Claims

1. A method for controlling engagement and release of pressure actuated torque establishing friction elements during a coasting downshift of a multiple-ratio transmission in a hybrid electric vehicle powertrain having an engine, an electric motor and a battery, the motor being disposed in a power flow path between the engine and a power input element of the transmission as driving power is delivered to a transmission power output member, and an electronic controller responsive to powertrain operating variables for controlling actuating pressure for the friction elements by releasing actuating pressure for an off-going friction element in synchronism with increasing actuating pressure for an oncoming friction element during a coasting downshift event, the method comprising the steps of:

commanding a torque level for the motor before a start of the coasting downshift, the torque level command being based on a desired negative regenerative braking torque;

commanding an initial high pressure for a pressure actuator for the oncoming friction element to fill the actuator quickly;

commanding a pressure for a pressure actuator for the off-going friction element to a level that is a function of transmission input torque;

ramping down the pressure of the pressure actuator for the off-going friction element during a coasting downshift start mode prior to an inertia phase of the coasting downshift;

controlling pressure of the actuator for the oncoming friction element using closed loop control during the inertia phase; and

ramping up electric motor torque from a current negative regenerative torque level, the desired negative torque level being a calibrated level for each coasting downshift.

2. The method set forth in claim 1 wherein the step of ramping electric motor torque includes the step of continuing the electric motor ramping during the coasting downshift until a time at which a desired transmission input torque is reached and clipping the electric motor torque at that value;

and

detecting an end of the inertia mode when the coasting downshift is near completion.

3. The method set forth in claim 1 wherein the step of commanding a high pressure of the pressure actuator for the oncoming friction element occurs prior to the inertia phase of the coasting downshift.

4. The method set forth in claim 1 wherein the step of ramping down the pressure of the pressure actuator of the off-going friction element continues until slipping of the oncoming friction element is detected.

5. The method set forth in claim 1 wherein the step of ramping down the pressure of the pressure actuator of the off-going friction element continues until torque capacity of the oncoming friction element is detected.

6. The method set forth in claim 1 including the step of ramping down a commanded motor torque beginning at a time when a predetermined percentage of coasting downshift completion is detected.

7. The method set forth in claim 6 wherein the ramping down of commanded motor torque occurs at a rate that is a function of percentage of coasting downshift completion.

8. The method set forth in claim 1 wherein the commanded high pressure for the pressure actuator for the oncoming friction element occurs during a fill time that is pre-calibrated.

9. The method set forth in claim 1 wherein the commanded pressure for the pressure actuator for the off-going friction element at the start of a coasting downshift is at a value that is sufficient to engage the off-going friction element with a capacity slightly in excess of the capacity of the off-going friction element.

10. The method set forth in claim 1 including the step of increasing to a high level a command for pressure for the actuator for the oncoming friction element at the completion of the coasting downshift.

11. The method set forth in claim 1 including the step of establishing a minimum pressure clip for the pressure for the actuator for the oncoming clutch during closed loop control in the inertia phase.

12. The method set forth in claim 1 including the step of reducing to zero the pressure of the actuator for the off-going friction element at the beginning of a coasting downshift to increase its rate of response as the pressure of the actuator for the oncoming friction element is boosted instantaneously prior to closed loop control.

13. A method for controlling engagement and release of pressure actuated torque establishing friction elements during a ratio change of a multiple-ratio transmission in a hybrid electric vehicle powertrain having an engine, an electric motor and a battery, the battery being electrically coupled to the motor, the motor being disposed in a power flow path between the engine and a power input element of the transmission as driving power is delivered to a transmission power output member, and an electronic controller responsive to power operating variables for controlling actuating pressure for the friction elements by releasing actuating pressure for an off-going friction element in synchronism with increasing actuating pressure for an oncoming friction element during a ratio change, the method comprising the steps of:

commanding a torque level for the motor before the start of a shift;

commanding an initial high pressure for a pressure actuator for the oncoming friction element to fill the actuator quickly; and

changing motor torque during a ratio change whereby the effective torque at the transmission power input member is modulated to effect a reduction in torque fluctuations at the power output member;

the torque at the transmission power input member being the algebraic sum of engine torque and motor torque.

14. A control system for controlling ratio changes in a multiple-ratio transmission in a hybrid electric vehicle powertrain, the transmission having selectively-engageable, pressure-actuated torque establishing friction elements for effecting powertrain upshifts;

the powertrain having an engine, an electric motor and a battery, the motor being disposed in a power flow path between the engine and a power input member of the transmission as driving power is delivered to a power output member;

the control system comprising an electronic controller responsive to powertrain operating variables for controlling actuating pressure for the friction elements;

the control system controller being configured to control actuating pressure for the friction elements by releasing actuating pressure for an off-going friction element in synchronism with increasing actuating pressure for an oncoming friction element during a power-on upshift;

the motor being disposed in series relationship with respect to the engine and the transmission; and

the control system including means for increasing motor torque during a torque phase and reducing motor torque during an inertia phase of a power-on upshift of the transmission.

15. A control system for controlling ratio changes in a multiple-ratio transmission of a hybrid electric vehicle powertrain, the transmission having selectively-engageable, pressure-actuated torque establishing friction elements for effecting coasting downshifts;

the powertrain having an engine, an electric motor and a battery, the motor being disposed in a power flow path between the engine and a power input member of the transmission as driving power is delivered to a power output member;

the control system comprising a controller responsive to powertrain operating variables for controlling actuating pressure for the friction elements;

the control system controller being configured to control actuating pressure for the friction elements during a coasting downshift in response to friction element slip speed changes as motor torque is increased during an inertia phase of a coasting downshift.