Drive power control apparatus and method for vehicle

• US 6,493,626 B2
• Filed: 05/17/2001
• Issued: 12/10/2002
• Est. Priority Date: 05/19/2000
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Mitani, Shinichi, Mashiki, Zenichiro, Kubota, Hirofumi, Takagi, Isao, Tanaka, Hiroya
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Donnelly, Arthur D.
• Application Number:
  US09/858,465
• Publication Number:
  US 20010044687A1
• Time in Patent Office: 572 Days
• Field of Search: 701/103, 701/104, 701/106, 701/54, 477/34, 477/37, 477/41, 477/42, 477/43, 123/704, 123/700, 123/486
• US Class Current: 701/103
• CPC Class Codes: B60W 10/04 including control of propulsion units
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/101 Infinitely variable gearings
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60W 30/188 Controlling power parameters of the driveline, e.g. determining the required power
• CPC Class Codes: F01N 3/0842 Nitrogen oxides
• CPC Class Codes: F01N 3/0871 Regulation of absorbents or adsorbents, e.g. purging by electrically controlling the supply of combustible mixture or its constituents only F02D41/0235
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 2400/12 Engine control specially adapted for a transmission comprising a torque converter or for continuously variable transmissions
• CPC Class Codes: F02D 41/0215 in relation with elements of the transmission
• CPC Class Codes: F02D 41/3029 further comprising a homogeneous charge spark-ignited mode
• CPC Class Codes: F16H 59/74 Inputs being a function of engine parameters F16H59/14 takes precedence
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• CPC Class Codes: Y02T 10/60 Other road transportation technologies with climate change mitigation effect

Abstract

An engine output for bringing the drive power of a motor vehicle to a requested value is determined as a target output. One of the lean burn and the stoichiometric burn is selected as a combustion form that achieves a best fuel consumption performance in terms of the control of the actual engine output to the target output. That is, an output value that serves as a criterion for determining whether to switch the combustion force is determined based on the minimum fuel consumption rate during the stoichiometric-burn operation and the minimum fuel consumption rate during the lean-burn operation in which the fuel consumption involved in the rich spike control is taken into account. If the target output is less than the output value, the lean-burn operation is performed. If the target output is greater than the output value, the stoichiometric-burn operation is performed.

Claims

1. A drive power control apparatus of a vehicle, comprising:

an internal combustion engine that changes a combustion form between a lean burn operation and a stoichiometric burn operation and that performs a rich spike control of temporarily shifting an air-fuel ratio to a fuel-rich air-fuel ratio during the lean burn operation;

a continuously variable transmission connected to an output shaft of the internal combustion engine;

a Nox storage-reduction catalyst provided in an exhaust system of the internal combustion engine; and

a controller which determines a target output of the engine for bringing a drive power of the vehicle to a target value and controls a torque of the internal combustion engine and a speed ratio of the continuously variable transmission so that an actual output of the internal combustion engine reaches the target output,

wherein the controller performs;

     1) the lean burn operation when the target output is less than an output value set based on a minimum fuel consumption rate during the stoichiometric burn operation and a minimum fuel consumption rate during the lean burn operation in which a fuel consumption involved in the rich spike control is taken into account,

     2) the stoichiometric burn operation when the target output is greater than the output value and

     3) the rich spike control to reduce a NOx stored in the NOx storage-reduction catalyst.

2. A control apparatus according to claim 1, wherein the controller determines the minimum fuel consumption rate during the stoichiometric burn operation and the minimum fuel consumption rate during the lean burn operation in which the fuel consumption involved in the rich spike control is taken into account, during an operation of the vehicle, and the controller calculates the output value based on the minimum fuel consumption rate during the stoichiometric burn operation and the minimum fuel consumption rate during the lean burn operation.

3. A control apparatus according to claim 2, wherein the minimum fuel consumption rate during the lean burn operation in which the fuel consumption involved in the rich spike control is taken into account is calculated based on a minimum fuel consumption rate during the lean burn operation without the rich spike control, and an extra amount of fuel consumption involved in the rich spike control.

4. A control apparatus according to claim 1,

wherein the controller changes an execution frequency of the rich spike control in accordance with a change in a NOx storing capability of the NOx storage-reduction catalyst, and

wherein the controller controls the output value in accordance with the change in the NOx storing capability of the NOx storage-reduction catalyst.

5. A control apparatus according to claim 4, further comprising a detector that detects a temperature of the NOx storage-reduction catalyst,

wherein the controller decreases the output value with increases in the temperature of a NOx storage-reduction catalyst.

6. A control apparatus according to claim 4, further comprising an estimator that estimates a degree of deterioration of the NOx storage-reduction catalyst,

wherein the controller decreases the output value with increases in a degree of deterioration.

7. A control apparatus according to claim 1,

wherein the controller changes an execution frequency of the rich spike control in accordance with a change in a NOx storing capability of the NOx storage-reduction catalyst, and

wherein the controller controls the output value in accordance with the change in the NOx storing capability of the NOx storage-reduction catalyst, and a speed of the vehicle.

8. A drive power control method in a vehicle having an internal combustion engine that changes a combustion form between a lean burn operation and a stoichiometric burn operation that performs a rich spike control of temporarily shifting an air fuel ratio to a fuel rich air fuel ratio during a lean burn operation, and a continuously variable transmission connected to an output shaft of the internal combustion engine, the method for controlling a torque of the internal combustion engine and a speed ratio of the continuously variable transmission so that an actual output of the internal combustion engine reaches the target output, the method comprising:

determining, as the target output, an output of the engine for bringing a drive power of the vehicle to a target value;

determining an output value of the internal combustion engine for selecting the combustion form based on a minimum fuel consumption rate during a stoichiometric burn operation and a minimum fuel consumption rate during a lean burn operation in which a fuel consumption involved in the rich spike control is taken into account;

performing the lean burn operation when the target output is less than the output value, and performing the stoichiometric burn operation when the target output is greater than the output value; and

performing the rich spike control so as to reduce a NOx stored in the NOx storage-reduction catalyst provided in the exhaust system of the internal combustion engine.

9. A control method accordance to claim 8, wherein the rich spike control is performed at a predetermined frequency in accordance with a change in a NOx storing capability of the NOx storage-reduction catalyst, and

wherein the minimum fuel consumption rate during the lean-burn operation used for determining the output value is calculated taking into account an amount of fuel consumed when the rich spike control is performed at the frequency corresponding to a predetermined state of the NOx storing capability of the NOx storage-reduction catalyst.

10. A control method according to claim 9, wherein the output value is changed in accordance with the change in the NOx storing capability of the NOx storage-reduction catalyst.

11. A control method according to claim 9, wherein the output value is changed in the NOx storing capability and a speed of the vehicle.

12. A drive power controller apparatus for an internal combustion engine and a continuously variable transmission connected to the internal combustion engine, the controller apparatus comprising:

a lean burn operation of the internal combustion engine that includes a rich spike control which temporarily shifts an air-fuel ratio from a lean burn operation to a fuel-rich operation;

a stoichiometric burn operation of the internal combustion engine;

a controller that controls a torque of the internal combustion engine and a speed ratio of the continuously variable transmission so that an actual output of the internal combustion engine reaches a target output for bringing a drive power of the vehicle to a target value, wherein the controller performs;

1) the lean burn operation when the target output is less than an output value set based on a minimum fuel consumption rate during the stoichiometric burn and a minimum fuel consumption rate during the lean burn; and

2) the stoichiometric burn operation when the target output is greater than the output value.

13. A method for controlling a torque of an internal combustion engine so that an actual output of the internal combustion engine reaches a target output, the method comprising:

obtaining a target output of the internal combustion engine for bringing a drive power of the vehicle to a target value;

setting an output value of the internal combustion engine based on a minimum fuel consumption rate in a stoichiometric burn operation and a minimum fuel consumption rate in a lean burn operation that includes a rich spike control fuel consumption, the rich spike control temporarily shifting an air-fuel ratio to a fuel-rich air-fuel ratio; and

performing the lean burn operation when the target output is less than the output value, and performing the stoichiometric burn operation when the target output is greater than the output value.