Control strategy for a hybrid powertrain for an automotive vehicle

• US 6,364,807 B1
• Filed: 06/30/2000
• Issued: 04/02/2002
• Est. Priority Date: 06/30/2000
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Gibson, Alexander O., Koneda, Philip Thomas, Megli, Thomas William
• Primary Examiner(s): ESTREMSKY, SHERRY LYNN
• Application Number:
  US09/607,829
• Time in Patent Office: 641 Days
• Field of Search: 477/5, 180/65.2, 123/179.3
• US Class Current: 477/5
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/946 Characterized by control of driveline clutch

Abstract

A control strategy for a hybrid powertrain for an automotive vehicle comprising an internal combustion engine, a geared transmission mechanism for transmitting driving torque to the vehicle traction wheels, and an electric motor arranged in parallel with respect to the internal combustion engine at the torque input side of the transmission. A friction clutch connects and disconnects the engine from the torque flow path as transitions are made between an electric motor driving mode and an engine driving mode. A mechanical damper is located on the torque input side of the clutch. A transition from the electric motor drive mode to the internal combustion engine drive mode is achieved by controlling the engagement of the clutch using a closed loop clutch pressure modulation strategy and controlling the fuel supply to the engine to effect an engine drive mode without triggering undesirable inertia torque fluctuations in the powertrain.

Claims

1. A control strategy and method for controlling a pressure-operated engine clutch in a throttle-controlled, hybrid powertrain for an automotive vehicle, the clutch being located at the torque input side of a multiple-ratio power transmission mechanism, the powertrain including a throttle-controlled internal combustion engine and a mechanical spring damper located in a torque flow path between the engine and the clutch, the torque output side of the transmission being connected drivably to traction wheels for the vehicle, and an electric motor in the torque flow path between the damper and the torque input side of the transmission, the strategy and method comprising the steps of:

launching the vehicle from a standing start by disengaging the clutch and energizing the electric motor while the clutch is disengaged;

controlling the motor using a motor torque control wherein electric power supplied to the motor is a function of throttle position, the throttle position being an indication of commanded torque;

commanding a transition from a motor power mode to an engine power mode during a transition time interval;

partially energizing the clutch at the beginning of the transition time interval;

modulating the pressure applied to the clutch to effect slipping of the clutch during the transition time interval, the clutch pressure being a function of the difference between clutch speed and engine starting speed whereby the motor is in a speed control mode;

applying full clutch pressure to the clutch when engine starting speed is approximately equal to motor speed; and

activating engine fueling.

2. The strategy and method set forth in claim 1 including the steps of monitoring commanded engine torque based on throttle position and monitoring motor torque as engine torque increases, and effecting torque delivery through the driveline using throttle control and terminating speed control as the vehicle is powered using engine power solely.

3. The control strategy and method set forth in claim 2 wherein the engine starting speed is greater than powertrain resonant speed of the powertrain system defined by the mass of engine rotary members, the mass of the motor rotary members and the spring damper characteristic of the mechanical spring damper.

4. The control strategy and method set forth in claim 1 wherein the engine starting speed is greater than powertrain resonant speed of the powertrain system defined by the mass of engine rotary members, the mass of the motor rotary members and the spring damper characteristic of the mechanical spring damper.

5. A control strategy and method for controlling a pressure-operated engine clutch in a throttle-controlled, hybrid powertrain for an automotive vehicle, the clutch being located at the torque input side of a multiple-ratio power transmission mechanism, the powertrain including a throttle controlled internal combustion engine and a mechanical spring damper located in a torque flow path between the engine and the clutch, throttle position being an indicator of commanded powertrain torque, the torque output side of the transmission being connected to traction wheels for the vehicle, and an electric motor in the torque flow path between the damper and the torque input side of the transmission, the strategy and method comprising the steps of:

starting the engine using the electric motor as a starter motor when the vehicle is stationary prior to launch of the vehicle using engine power solely;

the step of starting the engine comprising partially engaging the clutch when the vehicle is stationary;

modulating pressure of the clutch using closed-loop feedback motor speed control whereby pressure of the clutch is proportional to the difference between commanded engine starting speed and actual clutch speed as the clutch slips thereby attenuating inertial torque disturbances;

engaging the clutch fully when the clutch speed is approximately equal to engine starting speed; and

effecting fueling of the engine after the clutch is fully engaged.