Throttle control for internal combustion engine having failure detection function

• US 6,199,535 B1
• Filed: 05/10/2000
• Issued: 03/13/2001
• Est. Priority Date: 05/13/1999
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Hara, Mitsuo
• Primary Examiner(s): Kwon, John
• Application Number:
  US09/568,137
• Time in Patent Office: 307 Days
• Field of Search: 123/396, 123/399, 477/206
• US Class Current: 123/396
• CPC Class Codes: F02D 11/107 Safety-related aspects
• CPC Class Codes: F02D 2009/0277 Fail-safe mechanisms, e.g. with limp-home feature, to close throttle if actuator fails, or if control cable sticks or breaks
• CPC Class Codes: F02D 2011/102 at least one throttle being moved only by an electric actuator
• CPC Class Codes: F02D 2041/227 Limping Home, i.e. taking specific engine control measures at abnormal conditions
• CPC Class Codes: F02D 2200/0404 Throttle position
• CPC Class Codes: F02D 2200/602 Pedal position
• CPC Class Codes: F02D 2400/08 Redundant elements, e.g. two sensors for measuring the same parameter
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123

Abstract

A throttle valve for an engine is disabled to be driven by an actuator by limiting a target throttle angle upper limit of a target throttle angle, when a failure is detected by an electronic control unit. Then, the target throttle angle is returned to a value used at a normal time at a restoration timing of a restoration of the system to a normal state or while the opening speed of a throttle valve at a restoration is being restrained. Thus, an abrupt opening operation of the throttle valve in response to the depression carried out by the driver on an accelerator pedal. Further, the throttle valve is driven in a limp-home operation mode by controlling the reduced number of operating cylinders of the engine. The reduced number of operating cylinders is increased or the operations of all cylinders are halted, when the engine speed rises above a predetermined value.

Claims

1. A throttle control apparatus for an internal combustion engine comprising:

an accelerator position sensor for detecting an accelerator position according to a depression position of an accelerator pedal;

a throttle angle sensor for detecting an actual opening of a throttle valve as an actual throttle angle;

control variable calculation means for calculating a control variable for making the actual throttle angle detected by the throttle angle sensor match a target throttle angle on the basis of a deviation between the actual throttle angle and the target throttle angle which is a target opening of the throttle valve set in accordance with the accelerator position detected by the accelerator position sensor;

throttle control means for controlling the actual throttle angle by driving an actuator in accordance with the control variable calculated by the control variable calculation means;

failure detection means for detecting a failure in a throttle control;

fail-safe means for restraining an upper limit of the target throttle angle to be smaller than a predetermined value in the event of at least a failure detected in the throttle control apparatus; and

restoration control means for restoring the target throttle angle restrained by the fail-safe means to a value used in a normal time when the throttle control means is restored to a normal state.

2. A throttle control apparatus as in claim 1, wherein:

the restoration control means restores the upper limit of the target throttle angle to a value used at a normal time when the target throttle angle becomes smaller than at least one of (a) the predetermined throttle angle and (b) the actual throttle angle.

3. A throttle control apparatus as in claim 1, wherein:

the restoration control means gradually increases an upper limit of the target throttle angle.

4. A throttle control apparatus as in claim 1, wherein:

the restoration control means limits an opening speed of the throttle valve only during a period in which the target throttle angle is greater than the actual throttle angle after the restoration control is started.

5. A throttle control apparatus as in claim 1, wherein:

the restoration control means limits an opening speed of the throttle valve only during a predetermined period after the restoration control is started.

6. A throttle control apparatus as in claim 1, wherein:

the restoration control means gradually relieves a limitation on an opening speed of the throttle valve.

7. A throttle control apparatus as in claim 1 further comprising:

reduced cylinder count control means for executing reduced cylinder count control by setting a reduced cylinder count indicating the number of operating cylinders of the internal combustion engine after processing carried out by the fail-safe means; and

reduced cylinder count limitation means for setting a lower limit of the reduced cylinder count set by the reduced cylinder count control means in order to limit the number of operating cylinders.

8. A throttle control apparatus as in claim 7, further comprising:

brake detection means for detecting a state of a depression of a brake pedal,

wherein the reduced cylinder count control means sets the reduced cylinder count in accordance with the state of a depression of the brake pedal detected by the brake detection means and the accelerator position detected by the accelerator position sensor.

9. A throttle control apparatus as in claim 7, further comprising:

an engine speed sensor for detecting an engine speed of the internal combustion engine,

wherein the reduced cylinder count limitation control means increases the lower limit of the reduced cylinder count or halts operations of all cylinders when the engine speed detected by the engine speed sensor becomes greater than a predetermined engine speed.

10. A throttle control apparatus as in claim 9, wherein:

the reduced cylinder count limitation control means sets the predetermined engine speed in accordance with at least one of (a) the brake state detected by the brake detection means, (b) the accelerator position detected by the accelerator position sensor and (c) the actual throttle angle detected by the throttle angle sensor.

11. A throttle control apparatus as in claim 10, wherein:

the reduced cylinder count limitation control means sets the predetermined engine speed at a fixed engine speed when a failure is detected in any component used in setting the predetermined engine speed.

12. A throttle control apparatus as in claim 7, wherein:

the reduced cylinder count limitation control means sets the lower limit of the reduced cylinder count in accordance with at least one of (a) the accelerator position detected by the accelerator position sensor and (b) the actual throttle angle detected by the throttle angle sensor.

13. A throttle control apparatus as in claim 7, wherein:

the reduced cylinder count limitation control means sets at least one of (a) a limit of the lower limit of the reduced cylinder count at a predetermined value and (b) the reduced cylinder count at a fixed value without regard to;

(i) a reduced cylinder count set by the reduced cylinder count control means and (ii) the reduced cylinder count limitation means when a braking operation is detected by brake detection means.

14. A throttle control apparatus for an internal combustion engine comprising:

an accelerator position sensor for detecting an accelerator position of an accelerator pedal;

a throttle angle sensor for detecting an actual opening of a throttle valve as an actual throttle angle;

control variable calculation means for calculating a control variable for making the actual throttle angle detected by the throttle angle sensor match a target throttle angle on the basis of a deviation between the actual throttle angle and the target throttle angle which is a target opening of the throttle valve set in accordance with the accelerator position detected by the accelerator position sensor;

throttle control means for controlling the actual throttle angle by driving an actuator in accordance with the control variable calculated by the control variable calculation means;

failure detection means for detecting a failure in a throttle control;

fail-safe means for restraining an upper limit of the target throttle angle to a value smaller than a predetermined value in the event of at least a failure detected in the throttle control;

reduced cylinder count control means for executing reduced cylinder count control by setting a reduced cylinder count indicating the number of operating cylinders of the internal combustion engine after processing carried out by the fail-safe means; and

reduced cylinder count limitation means for setting a lower limit of the reduced cylinder count set by the reduced cylinder count control means in order to limit the number of operating cylinders.

15. A throttle control apparatus as in claim 14, further comprising:

brake detection means for detecting a state of a depression of a brake pedal,

wherein the reduced cylinder count control means sets the reduced cylinder count in accordance with the state of a depression of the brake pedal detected by the brake detection means and the accelerator position detected by the accelerator position sensor.

16. A throttle control apparatus as in claim 14, further comprising:

an engine speed sensor for detecting an engine speed of the internal combustion engine,

wherein the reduced cylinder count limitation control means increases the lower limit of the reduced cylinder count or halts operations of all cylinders when the engine speed detected by the engine speed sensor becomes greater than a predetermined engine speed.

17. A throttle control apparatus as in claim 16, wherein:

the reduced cylinder count limitation control means sets the predetermined engine speed in accordance with at least one of;

(a) a brake state detected by brake detection means, (b) the accelerator position detected by the accelerator position sensor and (c) the actual throttle angle detected by the throttle angle sensor.

18. A throttle control apparatus as in claim 17, wherein:

the reduced cylinder count limitation control means sets the predetermined engine speed at a fixed engine speed when a failure is detected in any component used in setting the predetermined engine speed.

19. A throttle control apparatus as in claim 14 wherein:

the reduced cylinder count limitation control means sets the lower limit of the reduced cylinder count in accordance with atleast one of;

(a) the accelerator position detected by the accelerator position sensor and (b) the actual throttle angle detected by the throttle angle sensor.

20. A throttle control apparatus as in claim 14, wherein:

the reduced cylinder count limitation control means sets at least one of;

(a) a limit of the lower limit of the reduced cylinder count at a predetermined value and (b) the reduced cylinder count at a fixed value without regard to;

(i) a reduced cylinder count set by the reduced cylinder count control means and (ii) the reduced cylinder count limitation means when a braking operation is detected by brake detection means.