Parallel hybrid vehicle employing parallel hybrid system, using both internal combustion engine and electric motor generator for propulsion

• US 6,441,506 B2
• Filed: 01/23/2001
• Issued: 08/27/2002
• Est. Priority Date: 03/07/2000
• Status: Expired due to Term

• Current Assignee: Jatco Limited (Nissan Motor Co., Ltd.)
• Original Assignee: Jatco Transtechnology Limited
• Inventors: Nakashima, Kenji
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US09/766,836
• Publication Number:
  US 20010020789A1
• Time in Patent Office: 581 Days
• Field of Search: 290/17, 290/40.R, 290/41, 290/40.C, 318/139, 180/65.2, 123/179.1
• US Class Current: 290/40.00C
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/383 One-way clutches or freewheel devices
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/54 Transmission for changing ratio
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• 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 2050/001 Proportional integral [PI] controller
• CPC Class Codes: B60W 2050/0011 Proportional Integral Differential [PID] controller
• CPC Class Codes: B60W 2050/0022 Gains, weighting coefficients or weighting functions
• CPC Class Codes: B60W 2050/0042 Transfer function lag; delays
• CPC Class Codes: B60W 2050/0052 Filtering, filters
• CPC Class Codes: B60W 2510/0614 Position of fuel or air injector
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/0652 Speed change rate
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/065 : Idle condition
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/909 : Gearing
• CPC Class Codes: Y10S 903/91 : Orbital, e.g. planetary gears
• CPC Class Codes: Y10S 903/913 : One way
• CPC Class Codes: Y10S 903/914 : Actuated, e.g. engaged or disengaged by electrical, hydraulic or mechanical means
• CPC Class Codes: Y10S 903/917 : with transmission for changing gear ratio
• CPC Class Codes: Y10S 903/945 : Characterized by control of gearing, e.g. control of transmission ratio
• CPC Class Codes: Y10S 903/946 : Characterized by control of driveline clutch

Abstract

In a parallel hybrid vehicle employing a parallel hybrid system, using both an internal combustion engine and an electric motor generator for propulsion, a desired motor/generator torque is map-retrieved based on both the engine speed and throttle opening from a predetermined characteristic map in a fashion of feedforward processing. The signal indicative of the desired motor/generator torque is subjected to a low-pass filter that passes signals included in a frequency band lower than an oscillation frequency of powertrain torsional vibrations to remove the powertrain vibration frequency components. The map is preprogrammed so that the desired motor/generator torque is set at zero in a specified speed range lower than an engine idle speed. In another specified speed range from the engine idle speed to a predetermined direct-coupling engine speed that permits the motor/generator to be directly coupled with the engine, a gain of the desired motor/generator torque is set to increase with an increase in the engine speed. In a specified speed range above the predetermined direct-coupling engine speed, the motor/generator is coupled directly with the engine, so that the motor/generator torque output produced from the motor/generator is substantially identical to the engine torque output.

Claims

1. A parallel hybrid vehicle employing a parallel hybrid system, using both an internal combustion engine and an electric motor generator for propulsion, said parallel hybrid vehicle comprising:

a torque composition mechanism which combines a torque output produced by the engine and a torque output produced by the motor generator to generate a combined torque, and which is connected via a transmission in a powertrain to drive wheels to output the combined torque via the transmission to the drive wheels;

a direct-coupling clutch which directly couples the engine with the motor generator;

an engine-speed sensor which detects engine speed of the engine;

a throttle opening sensor which detects a throttle opening of a throttle valve;

a controller being connected electrically to the motor generator and the direct-coupling clutch for controlling the torque output produced by the motor generator and engagement and disengagement of the direct-coupling clutch, said controller allowing the direct-coupling clutch to operate in a disengaged state and allowing the engine speed to be maintained at a predetermined value during starting of the vehicle;

said controller comprising;

(a) a desired motor/generator torque setting section which sets a desired motor/generator torque on the basis of both the engine speed and the throttle opening from a predetermined characteristic map to generate a signal indicative of the desired motor/generator torque, and

(b) a response-characteristic compensation section which attenuates high-input-frequency components and passes low-input-frequency components, out of the signal indicative of the desired motor/generator torque set through the desired motor/generator torque setting section, to generate a compensated signal; and

said controller controlling the torque output of the motor generator on the basis of a signal value of the compensated signal generated by the response-characteristic compensation section.

2. The parallel hybrid vehicle as claimed in claim 1, wherein the response-characteristic compensation section comprises either of a low-pass filter that passes signals at a frequency below a predetermined cut-off frequency and attenuates signals with a frequency above the predetermined cut-off frequency, and an integrator that produces a low gain at the high-input-frequency components and produces a high gain at the low-input-frequency components.

3. The parallel hybrid vehicle as claimed in claim 1, wherein the predetermined characteristic map is preprogrammed so that the torque output produced from the engine is greater than the desired motor/generator torque in a specified engine speed range below a predetermined engine speed which is set at a value substantially corresponding to an idle speed of the engine.

4. The parallel hybrid vehicle as claimed in claim 1, wherein the predetermined characteristic map is preprogrammed so that the desired motor/generator torque reaches a value substantially corresponding to the torque output produced from the engine in a specified engine speed range which is set at engine speeds that permit the motor generator to be directly coupled with the engine via the direct-coupling clutch after the starting of the vehicle.

5. The parallel hybrid vehicle as claimed in claim 1, wherein the predetermined characteristic map is preprogrammed so that, at a specified throttle opening of the throttle valve, the desired motor/generator torque is set to be greater with an increase in the engine speed and a rate of increase in the desired motor/generator torque is smaller with the increase in the engine speed.

6. The parallel hybrid vehicle as claimed in claim 2, wherein the predetermined characteristic map is preprogrammed so that the torque output produced from the engine is greater than the desired motor/generator torque in a specified engine speed range below a predetermined engine speed which is set at a value substantially corresponding to an idle speed of the engine.

7. The parallel hybrid vehicle as claimed in claim 2, wherein the predetermined characteristic map is preprogrammed so that the desired motor/generator torque reaches a value substantially corresponding to the torque output produced from the engine in a specified engine speed range which is set at engine speeds that permit the motor generator to be directly coupled with the engine via the direct-coupling clutch after the starting of the vehicle.

8. The parallel hybrid vehicle as claimed in claim 2, wherein the predetermined characteristic map is preprogrammed so that, at a specified throttle opening of the throttle valve, the desired motor/generator torque is set to be greater with an increase in the engine speed and a rate of increase in the desired motor/generator torque is smaller with the increase in the engine speed.

9. The parallel hybrid vehicle as claimed in claim 2, wherein, when the response-characteristic compensation section comprises the low-pass filter, the controller comprises a low-pass filter setting section which sets a frequency characteristic of the low-pass filter, the low-pass filter setting section being responsive to a reduction ratio of the transmission so as to set the frequency characteristic of the low-pass filter at a higher level with a decrease in the reduction ratio.

10. The parallel hybrid vehicle as claimed in claim 2, wherein, the transmission comprises an engine-braking clutch which enables a back driving torque input from a road surface to the drive wheels to be transmitted to the torque composition mechanism via the engine-braking clutch engaged, and when the response-characteristic compensation section comprises the low-pass filter, the controller comprises a low-pass filter setting section which sets a frequency characteristic of the low-pass filter, the low-pass filter setting section being responsive to a transition between an engaged state of the engine-braking clutch and a disengaged state of the engine-braking clutch so as to set the frequency characteristic of the low-pass filter at a higher level in presence of a transition from the engaged state of the engine-braking clutch to the disengaged state and to set the frequency characteristic of the low-pass filter at a lower level in presence of a transition from the disengaged state of the engine-braking clutch to the engaged state.

11. The parallel hybrid vehicle as claimed in claim 2, wherein, when the response-characteristic compensation section comprises the low-pass filter, the controller comprises a low-pass filter setting section which sets a frequency characteristic of the low-pass filter, the low-pass filter setting section being responsive to a transition between an engaged state of the direct-coupling clutch and a disengaged state of the direct-coupling clutch so as to set the frequency characteristic of the low-pass filter at a higher level in presence of a transition from the engaged state of the direct-coupling clutch to the disengaged state, and to set the frequency characteristic of the low-pass filter at a lower level in presence of a transition from the disengaged state of the direct-coupling clutch to the engaged state.

12. The parallel hybrid vehicle as claimed in claim 1, wherein the desired motor/generator torque setting section calculates a time mean of input information data indicative of the engine speed detected by the engine speed sensor, for setting the desired motor/generator torque based on the time mean of input information data indicative of the engine speed.

13. The parallel hybrid vehicle as claimed in claim 1, wherein the desired motor/generator torque setting section calculates a time mean of input information data indicative of the throttle opening detected by the throttle opening sensor, for setting the desired motor/generator torque based on the time mean of input information data indicative of the throttle opening.

14. The parallel hybrid vehicle as claimed in claim 1, wherein the desired motor/generator torque setting section calculates a time mean of the desired motor/generator torque to produce a signal indicative of the time mean of the desired motor/generator torque, and produces a compensated motor/generator torque command by passing the signal indicative of the time mean of the desired motor/generator torque through the response-characteristic compensation section, and the controller controls the torque output of the motor generator in response to the compensated motor/generator torque command.

15. A parallel hybrid vehicle employing a parallel hybrid system, using both an internal combustion engine and an electric motor generator for propulsion, said parallel hybrid vehicle comprising:

a torque composition means including a differential system for combining a torque output produced by the engine and a torque output produced by the motor generator to generate a combined torque, said torque composition means connected via a transmission in a powertrain to drive wheels for outputting the combined torque via the transmission to the drive wheels;

a direct-coupling clutch which directly couples the engine with the motor generator;

an engine-speed sensor means for detecting engine speed of the engine;

a throttle opening sensor means for detecting a throttle opening of a throttle valve;

a torque control means connected electrically to the motor generator and the direct-coupling clutch for controlling the torque output produced by the motor generator and engagement and disengagement of the direct-coupling clutch, said torque control means allowing the direct-coupling clutch to operate in a disengaged state and allowing the engine speed to be maintained at a predetermined value and allowing the direct-coupling clutch to engage at a timing when the engine speed synchronizes a rotational speed of the motor generator during starting of the vehicle;

said torque control means comprising;

(a) a desired motor/generator torque setting means for setting a desired motor/generator torque on the basis of both the engine speed and the throttle opening from a predetermined characteristic map to generate a signal indicative of the desired motor/generator torque, and

(b) a response-characteristic compensating means for attenuating high-input-frequency components and for passing low-input-frequency components, out of the signal indicative of the desired motor/generator torque set through the desired motor/generator torque setting means, to generate a compensated signal; and

said torque control means controlling the torque output of the motor generator on the basis of a signal value of the compensated signal generated by the response-characteristic compensating means.

16. The parallel hybrid vehicle as claimed in claim 15, wherein, the response-characteristic compensating means comprises the low-pass filter, and the controller comprises a low-pass filter setting section which sets a frequency characteristic of the low-pass filter, the low-pass filter setting section being responsive to a reduction ratio of the transmission so as to set the frequency characteristic of the low-pass filter at a higher level with a decrease in the reduction ratio.

17. The parallel hybrid vehicle as claimed in claim 15, wherein, the transmission comprises an engine-braking clutch which enables a back driving torque input from a road surface to the drive wheels to be transmitted to the torque composition mechanism via the engine-braking clutch engaged, and when the response-characteristic compensating means comprises the low-pass filter, the controller comprises a low-pass filter setting section which sets a frequency characteristic of the low-pass filter, the low-pass filter setting section being responsive to a transition between an engaged state of the engine-braking clutch and a disengaged state of the engine-braking clutch so as to set the frequency characteristic of the low-pass filter at a higher level in presence of a transition from the engaged state of the engine-braking clutch to the disengaged state and to set the frequency characteristic of the low-pass filter at a lower level in presence of a transition from the disengaged state of the engine-braking clutch to the engaged state.

18. An electronic control method for a parallel hybrid vehicle employing a parallel hybrid system, using both an internal combustion engine and an electric motor generator for propulsion and including a direct-coupling clutch directly coupling the engine with the motor generator, and an engine-braking clutch incorporated in a transmission in a powertrain, the electronic control method comprising:

detecting a throttle opening of a throttle valve;

calculating an average throttle opening as a time mean of the throttle opening;

detecting engine speed of the engine;

calculating an average engine speed as a time mean of the engine speed;

retrieving a desired motor/generator torque of the motor generator on the basis of the average throttle opening and the average engine speed from a predetermined characteristic map to produce a signal indicative of the desired motor/generator torque;

calculating an average desired motor/generator torque as a time mean of the desired motor/generator torque;

detecting a reduction ratio of the transmission in the powertrain;

detecting input information regarding which state the direct-coupling clutch is in;

detecting input information regarding which state the engine-braking clutch is in;

selecting a response-characteristic-compensator frequency characteristic responsively to the reduction ratio of the transmission, the input information regarding which state the direct-coupling clutch is in, and the input information regarding which state the engine-braking clutch is in;

making a response-characteristic compensating process of the selected response-characteristic-compensator frequency characteristic to the signal indicative of the average desired motor/generator torque to generate a compensated motor/generator torque command; and

controlling the motor generator in response to the compensated motor/generator torque command.

19. The method as claimed in claim 18, wherein the response-characteristic-compensator frequency characteristic is set at a higher level with a decrease in the reduction ratio of the transmission.

20. The method as claimed in claim 18, wherein the response-characteristic-compensator frequency characteristic is set at a higher level in presence of a transition from an engaged state of the engine-braking clutch to a disengaged state and set at a lower level in presence of a transition from the disengaged state of the engine-braking clutch to the engaged state, and wherein the response-characteristic-compensator frequency characteristic is set at a higher level in presence of a transition from an engaged state of the direct-coupling clutch to a disengaged state and set at a lower level in presence of a transition from the disengaged state of the direct-coupling clutch to the engaged state.