Operating method for a hybrid car

• US 5,785,138 A
• Filed: 07/28/1997
• Issued: 07/28/1998
• Est. Priority Date: 05/15/1992
• Status: Expired due to Term

• Current Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Original Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Inventors: Yoshida, Masato
• Primary Examiner(s): Johnson, Brian L.
• Assistant Examiner(s): LERNER, AVRAHAM H
• Application Number:
  US08/901,259
• Time in Patent Office: 365 Days
• Field of Search: 180/65.1, 180/65.2, 180/65.3, 180/65.4, 60/300, 60/302, 60/303, 290/16, 290/17, 290/45, 290/50
• US Class Current: 180/65.245
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/425 Temperature
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/445 Temperature
• CPC Class Codes: B60L 2250/28 Accelerator pedal thresholds
• CPC Class Codes: B60L 2270/12 of exhaust
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• 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 10/26 for electrical energy, e.g. batteries or capacitors
• 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 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 2510/068 Engine exhaust temperature
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/0622 Air-fuel ratio
• CPC Class Codes: B60W 2720/10 Longitudinal speed
• CPC Class Codes: B60W 2720/106 : Longitudinal acceleration
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A method and apparatus for operating a hybrid car which includes an electric motor for driving the car, and an internal combustion engine for power generation. At least first and second vehicle operating parameters, such as accelerator pedal depression depth and actual vehicle velocity, are detected. Based on these vehicle operating parameters, a controller controls the electric motor. From these vehicle operating parameters, a vehicle operating state is determined. The charge state of a battery, which supplies electric power to the electric motor, is also detected. Based on the charge state and the vehicle operating state, a target engine operating state is set for the internal combustion engine. The target engine operating states are determined so that low fuel consumption is ensured. The controller then controls the internal combustion engine to achieve the target engine operating state.

Claims

1. A method for operating a hybrid car, comprising:

providing an electric motor to drive driving wheels of said hybrid car;

providing a battery to supply electrical power to said electric motor;

providing a generator to charge said battery, said generator being provided independently from said electric motor;

providing an internal combustion engine to drive said generator, said internal combustion engine driving said generator without providing output torque to said motor;

sensing, with at least first and second sensors, at least an actual vehicle velocity and a depression degree of an accelerator pedal;

establishing a predetermined target vehicle velocity based on said sensed depression degree;

controlling said electric motor based on said sensed actual vehicle velocity and said established predetermined target vehicle velocity;

determining a charge state of said battery;

setting a target engine operating state in accordance with at least said charge state; and

controlling said internal combustion engine to achieve said target engine operating state.

2. The method of claim 1, wherein said setting step sets said target engine operating state as one of at least first and second predetermined engine operating states, and at least one of said first and second predetermined engine operating states reduces fuel consumption of said internal combustion engine.

3. The method of claim 1, wherein

said sensing step senses the accelerator depression degree as a first vehicle operating parameter, and said actual vehicle velocity as a second vehicle operating parameter;

and

said controlling step includes the steps of;

computing said target vehicle velocity based on said accelerator pedal depression depth,

setting a target acceleration based on said target vehicle velocity and said actual vehicle velocity,

determining a required motor output based on said target acceleration and said actual vehicle velocity, and

computing a drive current to output to said electric motor based on said required motor output.

4. The method of claim 1, wherein said controlling step gradually varies an operating state of said internal combustion engine to achieve said target engine operating state.

5. The method of claim 1, further comprising the step of:

determining a vehicle operating state; and

wherein

said setting step sets said target engine operating state in accordance with said charge state and said vehicle operating state.

6. The method of claim 5, wherein

said charge state determining step determines whether the battery is in one of sufficiently charged state and an insufficiently charged state;

said vehicle operating state determining step determines said vehicle operating state as one of a low-speed, low-load state, medium-speed, medium/high-load state, or a high-speed state based on said first and second vehicle operating parameters; and

said setting step includes the steps of,

setting said target engine operating state to an off state such that said internal combustion engine stops operating when said charge state determining step determines said sufficiently charged state,

setting said target engine operating state to a low-speed, low-load state when said charge state determining step determines said insufficiently charged state and said vehicle operating state determining step determines said low-speed, low-low state,

setting said target engine operating state to a medium-speed, medium-load state when said charge state determining step determines said insufficiently charged state and said vehicle operating state determining step determines said medium-speed, medium/high state, and

setting said target engine operating state to a high-speed, high-load state when said charge state determining step determines said insufficiently charged state and said vehicle operating state determining step determines said high-speed state.

7. The method of claim 6, wherein said internal combustion engine controlling step controls said internal combustion engine to operate at an engine speed of 2,000 rpm and a mean effective pressure of 6 to 7 kgf/cm² in the low-speed, low-load state, at the engine speed of 3,000 rpm and the mean effective pressure of 8.5 kgm/cm² in the medium-speed, medium/high-load state, and at the engine speed of 4,000 rpm and the means effective pressure of 9 to 10 kgf/cm² in the high-speed state.

8. The method of claim 5, wherein

said charge state determining step determines whether the battery is in one of a sufficiently charged state and an insufficiently charged state;

said vehicle operating state determining step determines said vehicle operating state as one of a low/medium-load state or a high-load state based on said first and second vehicle operating parameters;

said setting step includes the steps of,

setting said target engine operating state to a standby state when said charge state determining step determines said sufficiently charged state,

setting said target engine operating state to a medium-speed, medium-load state when said charge state determining step determines said insufficiently charged state and said vehicle operating state determining step determines said low/medium-load state, and

setting said target engine operating state to a high-speed, high-load state when said charge state determining step determines said insufficiently charged state and said vehicle operating state determining step determines said high-load state.

9. The method of claim 8, wherein said internal combustion engine controlling step controls said internal combustion engine according to said standby state by adjusting a throttle valve of said internal combustion engine to a low opening, according to said medium-speed, medium-load state by adjusting said throttle valve of said internal combustion engine to a medium opening, and according to said high-speed, high-load state by adjusting said throttle valve of said internal combustion engine to a fully-open state.

10. The method of claim 8, wherein said internal combustion engine controlling step operates said internal combustion engine at an engine speed of 1,000 rpm and a mean effective pressure of 2 kgf/cm² in said standby state, at the engine speed of 3,000 rpm and the mean effective pressure of 8 kgf/cm² in said medium speed, medium-load state, and at the engine speed of 4,000 rpm and the mean effective pressure of 9 kgf/cm² in said high-speed, high-load state.

11. The method of claim 8, wherein said internal combustion engine controlling step controls said internal combustion engine such that lean combustion is made in the standby state, and combustion is made with a stoichiometric air-fuel ratio when in the medium-speed, medium-load state or the high-speed, high-load state.

12. The method of claim 8, wherein said internal combustion engine controlling step controls said internal combustion engine such that operation of said internal combustion engine in said standby state is started immediately after a starter key of said hybrid car is turned on to start said hybrid car running.

13. The method of claim 1, wherein

said charge state determining step determines whether the battery is in one of a sufficiently charged state and an insufficiently charged state;

said setting step includes the steps of,

(a) setting said target engine operating state to an idle state when said charge state determining determines said sufficiently charged state,

(b) setting said target engine operating state to a high-output state when said charge state determining determines said insufficiently charged state; and

said internal combustion engine controlling step adjusts said internal combustion engine to idle when step (a) sets said idle state, and adjusts said internal combustion engine to high output when said step (b) sets said high-output state.

14. The method of claim 13, wherein said internal combustion engine controlling step adjusts a throttle valve of said internal combustion engine to a near fully-closed position when said idle state is set, and adjusts said throttle valve to a fully-open position when said high-output state is set.

15. The method of claim 1, wherein

said charge state determining step determines whether the battery is in one of a sufficiently charged state and an insufficiently charged state;

said setting step includes the steps of,

(a) setting said target engine operating state to a low state when said charge state determining step determines said sufficiently charged state,

(b) setting said target engine operating state to a high state when said charge state determining step determines said insufficiently charged state; and

said internal combustion engine controlling step controls said internal combustion engine such that a throttle valve thereof is set to a first predetermined opening and a air-fuel ratio thereof is set for lean combustion when step (a) sets said low state, and controls said internal combustion engine such that said throttle valve is set to a second predetermined opening and said air-fuel ratio is set to stoichiometric value when said step (b) sets said high state, and said first predetermined opening is less than said second predetermined opening.

16. The method of claim 1, wherein said setting step sets a target engine speed and a target mean effective pressure as said target engine operating state.

17. The method of claim 16, further comprising:

setting a target throttle value opening based on said target engine speed and said target mean effective pressure; and

wherein

said controlling step controls said internal combustion engine based on said target throttle valve opening.

18. A method for operating a hybrid car, said hybrid car including an electric motor for driving said hybrid car, a battery for supplying electric power to said electric motor, a generator for charging said battery, an internal combustion engine operatively isolated from said electric motor and used to drive said generator, and an exhaust gas purifier with a catalyst for purifying exhaust gas from said internal combustion engine, the method comprising:

(a) sensing, with at least first and second sensors, at least first and second vehicle operating parameters, at least one of said at least first and second sensors detecting a parameter other than a depression degree of an accelerator pedal and a depression of a brake pedal;

(b) controlling said electric motor based on output at least said first and second vehicle operating parameters;

(c) determining a charge state of said battery;

(d) setting a target engine operating state in accordance with at least said charge state;

(e) controlling said internal combustion engine to achieve said target engine operating state;

(f) sensing a temperature of said catalyst;

(g) determining whether said catalyst is in one of a sufficiently heated state and an insufficiently heated state based on output of said step (f); and

wherein

said step (d) sets said target engine operating state to an off state such that said step (e) prohibits said internal combustion engine from operating when said step (g) determines said insufficiently heated state.

19. A system for operating a hybrid car, comprising:

an electric motor which drives driving wheels of said hybrid car;

a battery which supplies electrical power to said electric motor;

a generator which charges said battery, said generator being provided independently from said electric motor;

an internal combustion engine which drives said generator, said internal combustion engine driving said generator without providing output torque to said motor;

at least first and second sensors for sensing at least an actual vehicle velocity and a depression degree of an accelerator pedal;

a target vehicle velocity determining unit which establishes a predetermined target vehicle velocity based on said sensed depression degree;

a battery charge sensor for sensing a charge of said battery; and

control means for controlling said electric motor based on said sensed actual vehicle velocity and said established predetermined target vehicle velocity, for determining a charge state of said battery, for setting a target engine operating state in accordance with at least said charge state, and for controlling said internal combustion engine to achieve said target engine operating state.

20. The system of claim 19, wherein said control means sets said target engine operating state as one of at least first and second predetermined operating states, and at least one of said first and second predetermined engine operating states reduces fuel consumption of said internal combustion engine.

21. The system of claim 19, wherein

said first sensor senses the accelerator depression degree as a first vehicle operating parameter;

said second sensor senses said actual vehicle velocity as a second vehicle operating parameter; and

said control means controls said electric motor by (1) computing a target vehicle velocity based on said accelerator depression degree, (2) setting a target acceleration based on said target vehicle velocity and said actual vehicle velocity, (3) determining a required motor output based on said target acceleration and said actual vehicle velocity, and (4) computing a drive current to output to said electric motor based on said required motor output.

22. The system of claim 19, wherein

said control means determines a vehicle operating state;

and

said control means sets said target engine operating state in accordance with said charge state and said vehicle operating state.

23. The system of claim 22, wherein

said control means determines whether the battery is in one of a sufficiently charged state and an insufficiently charged state based on output of said battery charge sensor;

said control means determines said vehicle operating state as one of a low-speed, low-load state;

medium-speed, medium/high-load state;

or a high-speed state based on said first and second vehicle operating parameters; and

said control means sets said target engine operating state to an off state such that said internal combustion engine stops operating when said battery is in said sufficiently charged state, sets said target engine operating state to a low-speed, low-load state when said battery is in said insufficiently charged state and said vehicle operating state is said low-speed, low-load state, sets said target engine operating state to a medium-speed, medium-load state when said battery is in said insufficiently charged state and said vehicle operating state is said medium-speed, medium/high state, and sets said target engine operating state to a high-speed, high-load state when said battery is in said insufficiently charged state and said vehicle operating state is said high-speed state.

24. The system of claim 23, wherein said control means controls said internal combustion engine to operate at an engine speed of 2,000 rpm and a mean effective pressure of 6 to 7 kgf/cm² in the low-speed, low-load state, at the engine speed of 3,000 rpm and the mean effective pressure of 8.5 kgf/cm² in the medium-speed, medium/high-load state, and at the engine speed of 4,000 rpm and the means effective pressure of 9 to 10 kgf/cm² in the high-speed state.

25. The system of claim 22, wherein

said control means determines whether the battery is in one of a sufficiently charged state and an insufficiently charged state based on output from said battery charge sensor;

said control means determines said vehicle operating state as one of a low/medium-load state or a high-load state based on said first and second vehicle operating parameters;

said control means sets said target engine operating state to a standby state when said battery is in said sufficiently charged state, sets said target engine operating state to a medium-speed, medium-load state when said battery is in said insufficiently charged state and said vehicle operating state is said low/medium-load state, and setting said target engine operating state to a high-speed, high-load state when said battery is in said insufficiently charged state and said vehicle operating state is said high-load state.

26. The system of claim 25, wherein said control means controls said internal combustion engine according to said standby state by adjusting a throttle valve of said internal combustion engine to a low opening, according to said medium-speed, medium-load state by adjusting said throttle valve of said internal combustion engine to a medium opening, and according to said high-speed, high-load state by adjusting said throttle valve of said internal combustion engine to a fully-open state.

27. The system of claim 25, wherein said control means operates said internal combustion engine at an engine speed of 1,000 rpm and a mean effective pressure of 2 kgf/cm² in said standby state, at the engine speed of 3,000 rpm and the mean effective pressure of 8 kgf/cm² in said medium-speed, medium-load state, and at the engine speed of 4,000 and the mean effective pressure of 9 kgf/cm² in said high-speed, high-load state.

28. The system of claim 25, wherein said control means controls said internal combustion engine such that lean combustion is made in the standby state, and combustion is made with a stoichiometric air-fuel ratio when in the medium-speed, medium-load state or the high-speed, high-load state.

29. The system of claim 25, wherein said control means controls said internal combustion engine such that operation of said internal combustion engine in said standby state is started immediately after a starter key of said hybrid car is turned on to start said hybrid car running.

30. The system of claim 19, wherein said control means gradually varies an operating state of said internal combustion engine to achieve said target engine operating state.

31. The system of claim 19, wherein

said control means determines whether the battery is in one of a sufficiently charged state and an insufficiently charged state based on output of said battery charge sensor;

said control means sets said target engine operating state to an idle state when said battery is in said sufficiently charged state, sets said target engine operating state to a high-output state when said battery is in said insufficiently charged state; and

said control means adjusts said internal combustion engine to idle when said idle state is set, and adjusts said internal combustion engine to high output when said high-output state is set.

32. The system of claim 31, wherein said control means adjusts a throttle valve of said internal combustion engine to a near fully-closed position when said idle state is set, and adjusts said throttle valve to a fully-open position when said high-output state is set.

33. The system of claim 19, wherein

said control means determines whether the battery is in one of a sufficiently charged state and an insufficiently charged state based on output of said battery charge sensor;

said control means sets said target engine operating state to a low state when said battery is in said sufficiently charged state, sets said target engine operating state to a high state when said battery is in said insufficiently charged state; and

said control means controls said internal combustion engine such that a throttle valve thereof is set to a first predetermined opening and a air-fuel ratio thereof is set for lean combustion when said low state is set, and controls said internal combustion engine such that said throttle valve is set to a second predetermined opening and said air-fuel ratio is set to stoichiometric value when said high state is set, and said first predetermined opening is less than said second predetermined opening.

34. The system of claim 19, wherein said control means sets a target engine speed and a target mean effective pressure as said target engine operating state.

35. The system of claim 34, wherein said control means sets a target throttle value opening based on said target engine speed and said target mean effective pressure, and controls said internal combustion engine based on said target throttle value opening.

36. A system for operating a hybrid car, said hybrid car including an electric motor for driving said hybrid car, a battery for supplying electric power to said electric motor, a generator for charging said battery, an internal combustion engine operatively isolated from said electric motor and used to drive said generator, and an exhaust gas purifier with a catalyst for purifying exhaust gas from said internal combustion engine, the system comprising:

at least first and second sensors for sensing first and second vehicle operating parameters, respectively, at least one of said at least first and second sensors detecting a parameter other than a depression degree of an accelerator pedal and a depression of a brake pedal;

a battery charge sensor for sensing a charge of said battery; and

control means for controlling said electric motor based on at least said first and second vehicle operating parameters, for determining a charge state of said battery, for setting a target engine operating state in accordance with at least said charge state, and for controlling said internal combustion engine to achieve said target engine operating state;

a temperature sensor for sensing a temperature of said catalyst; and

wherein

said control means determines whether said catalyst is in one of a sufficiently heated state and an insufficiently heated state based on output of said temperature sensor; and

wherein

said control means sets said target engine operating state to an off state such that said control means prohibits said internal combustion engine from operating when said insufficiently heated state is determined.

37. A method for operating a hybrid car comprising:

providing an electric motor to drive driving wheels of said hybrid car;

providing a battery to supply electrical power to said electric motor;

providing a generator to charge said battery, said generator being provided independently from said electric motor;

providing an internal combustion engine to drive said generator, said internal combustion engine driving said generator without providing output torque to said motor;

sensing, with a first sensor, an actual vehicle velocity;

sensing, with a second sensor, a depression degree of an accelerator pedal to establish a predetermined target vehicle velocity;

controlling said electric motor based on said sensed actual vehicle velocity and said established predetermined target vehicle velocity;

determining a charge state of said battery;

setting a target engine operating state in accordance with at least said charge state; and

controlling said internal combustion engine to achieve said target engine operating state.