Strategy to control a clutch to connect an engine to a powertrain of a hybrid electric vehicle

• US 6,853,892 B2
• Filed: 09/09/2002
• Issued: 02/08/2005
• Est. Priority Date: 09/09/2002
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Cikanek, Susan Rebecca, Baraszu, Robert Charles
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US10/065,008
• Publication Number:
  US 20040045750A1
• Time in Patent Office: 883 Days
• Field of Search: 701/22, 701/1, 180/65.2, 743/35, 746/61, 477/5, 477/6, 477/79, 475/5, 192/12.R, 192/30.R, 192/40, 192/48.7
• US Class Current: 701/22
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 2050/0052 Filtering, filters
• CPC Class Codes: B60W 2510/0216 Clutch engagement rate
• CPC Class Codes: B60W 2510/0225 Clutch actuator position
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: F02N 11/04 the motors being associated with current generators
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y10S 903/919 Stepped shift
• CPC Class Codes: Y10S 903/946 Characterized by control of driveline clutch

Abstract

This invention is a control system for a clutch for connecting an engine to the powertrain of an HEV. The system includes a controller programmed to determine a filtered speed error of the engine and a starter/motor and to determine an engine run command. Monitoring devices operatively connected to the engine and the starter/motor are connected to output data representing the engine and starter/motor speeds to the controller. The controller is programmed to generate a clutch position command, dependent on the data, to a servo-actuator connected to the clutch. The invention, further, provides methods for controlling such a clutch including the steps of determining an engine run command, determining a filtered speed error of the engine and a starter/motor and generating a clutch position command.

Claims

1. A method to control a clutch to connect an engine to a powertrain of a hybrid electric vehicle (HEV), comprising the steps of:

determining an engine run command;

determining a filtered speed error of the engine and a starter/motor; and

generating a clutch position command.

2. The method of claim 1, wherein the HEV is a parallel HEV.

3. The method of claim 1, wherein the step of determining an engine run command comprises the steps of:

determining whether the clutch is engaged;

determining whether the engine is at least spinning at a predetermined idle speed;

commanding a fuel request to the engine when the clutch is engaged and the engine is spinning at least at the predetermined idle speed.

4. The method of claim 3 wherein the predetermined idle speed is 750 RPM.

5. The method of claim 1, wherein the step of determining a filtered speed error comprises the steps of:

determining a speed error;

determining a scaled speed error; and

inputting the scaled speed error to a digital lowpass filter.

6. The method of claim 5, wherein determining speed error comprises the steps of:

sensing starter/motor speed and engine speed; and

determining the difference of the starter/alternator speed and the engine speed.

7. The method of claim 5, wherein the step of determining scaled speed error comprises the steps of:

determining a speed gain; and

multiplying the speed gain and the speed error.

8. The method of claim 5, wherein the step of determining filtered speed error comprises the steps of:

multiplying the scaled speed error by a predetermined time constant (TC) and a current determination time step (K);

multiplying (1−

TC) by the filtered speed error and (k−

1); and

summing the step multiplying the scaled speed error by TC and a current determination time step (K) and the step of multiplying (1−

TC) by the filtered speed error and (k−

1).

9. The method of claim 8, wherein the predetermined time constant is 0.03.

10. The method of claim 1, wherein the step of generating a clutch position command comprises the steps of:

sensing actual clutch position, whether an accelerator is applied, and whether a mechanical braking device is applied;

inputting actual clutch position to a vehicle system controller;

determining whether engine speed is greater than a predetermined idle speed;

commanding engagement of the clutch when the braking device is applied and the engine speed is greater than a predetermined idle speed; and

commanding engagement of the clutch when both the braking device and the accelerator are applied and the engine speed is greater than a predetermined idle speed.

11. The method of claim 10, wherein the predetermined idle speed is 750 RPM.