Engine control system

• US 20030100975A1
• Filed: 04/23/2002
• Published: 05/29/2003
• Est. Priority Date: 11/28/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Hashimoto, Kohji, Nakamoto, Katsuya
• Granted Patent: US 6,799,110 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: F02D 11/107 Safety-related aspects
• 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 31/009 for maximum speed control
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809

Abstract

Evacuation operation performance is improved when any abnormality occurs in an electronic throttle control system.

When any serious abnormality occurs, a first abnormality storage element (133) operates, a load relay for a power supply circuit (104a) of a throttle valve open/close controlling motor (103) is de-energized to operate a first alarm and display (109a). Thus a first device carries out the evacuation operation by a fuel cut control.

When any slight abnormality occurs, a second abnormality storing element (136) comes to actuate thereby a second alarm and display (109b) being operated. Thus a second device carries out the evacuation operation using together a throttle valve opening control by the motor 103 and the fuel cut control.

Claims

1. An engine control system comprised of:

motor drive control means that is power fed via a power supply switch from a vehicle-mounted battery and controls an open/close driving motor of a throttle valve for an intake of the engine in response to an output from an accelerator position sensor for detecting a degree of a depression of an accelerator pedal and an output from a throttle position sensor for detecting a throttle valve opening;

fuel injection control means for the engine; and

engine speed or vehicle speed detecting means; and

includes a microprocessor (CPU);

said engine control system comprising multi-stage abnormality detecting means, multi-stage evacuation operation means, and evacuation operation mode selection means;

wherein said abnormality detecting means is multi-stage abnormality detecting means that regularly monitors operations of sensor system, control system and actuator system relating to a throttle valve control, and identifies and detects slight abnormality and serious abnormality depending on whether or not at least control of said actuator is possible;

said evacuation operation means is multi-stage evacuation operation means that responds to any abnormality result detected by said multi-stage abnormality detecting means, and comprises at least slight abnormality evacuation operation means and serious abnormality evacuation operation means; and

said evacuation operation mode selection means is means for selecting one of said multi-stage evacuation operation means so that shift from a normal operation when said slight abnormality or serious abnormality is not generated, to a side of getting worse in abnormality degree toward the slight abnormality evacuation operation or the serious abnormality evacuation operation may be possible, while shift to a return side in the abnormality degree may be impossible without interrupting said power supply switch.

2. The engine control system according to claim 1, further comprising smooth shift compensation means:

wherein

said smooth shift compensation means suppresses a sharp rise in the engine speed after the shift as compared with the engine speed in operation mode before the shift, at the time of shifting the operation mode toward said normal operation, slight abnormality evacuation operation and serious abnormality evacuation operation.

3. The engine control system according to claim 1, further comprising first or second throttle control means, first or second upper limit engine speed threshold setting means, first or second upper limit engine speed threshold computing means, fuel cut control means, first evacuation operation means as one of said serious abnormality evacuation operation means, and second evacuation operation means as one of said slight abnormality evacuation operation means:

wherein

said first throttle control means is drive control means that is applied when both of said accelerator position sensor and throttle position sensor are normal, and controls open and close of an air supply throttle valve by means of said driving motor so that an output detected by the normal throttle position sensor may be in a relation of substantially proportional to an output detected by the normal accelerator position sensor;

said second throttle control means is drive control means that is applied when said accelerator position sensor is normal while said throttle position sensor is abnormal, and controls the open and close of the air supply throttle valve by means of said driving motor so that an engine speed or vehicle speed detected by said engine speed or vehicle speed detecting means may be in a relation of substantially proportional to the output detected by the normal accelerator position sensor;

said first upper limit engine speed threshold setting means is setting means that selects and sets a predetermined engine speed not higher than a permissible maximum engine speed under the normal operation;

said second upper limit engine speed threshold setting means is setting means that selects and sets a predetermined engine speed not higher than the engine speed set by said first upper limit engine speed threshold setting means;

said first upper limit engine speed threshold computing means is computing means that is applied when said accelerator position sensor is normal, and computes a target upper limit engine speed so that the engine speed may be an engine speed substantially proportional to the output detected by the normal accelerator position sensor and also an engine speed not higher than that set by said first upper limit engine speed threshold setting means;

said second upper limit engine speed threshold computing means is computing means that is applied when said accelerator position sensor is abnormal and the throttle position sensor is normal, and computes the target upper limit engine speed so that the engine speed may be an engine speed substantially in inverse proportion to the output detected by the normal throttle position sensor and also an engine speed not higher than that set by said first upper limit engine speed threshold setting means;

said fuel cut control means is fuel injection control means that suppresses the fuel injection so that the engine speed detected by said engine speed detecting means may be not higher than the engine speed to be the target;

said first evacuation operation means is means that conducts the evacuation operation for controlling the engine speed by said fuel cut control means so that the engine speed computed by said first or second upper limit engine speed threshold computing means, or second upper limit engine speed threshold setting means may be the upper limit target engine speed; and

said second evacuation operation means is means that controls the engine speed by said fuel cut control means so that the engine speed set by said first upper limit engine speed threshold setting means may be the upper limit target engine speed, and carries out the evacuation operation at a variable engine speed by said first or second throttle control means.

4. The engine control system according to claim 3, further comprising switching means for switching the power supply, a default mechanism, first and second abnormality storage elements, first and second alarm displays, and a power supply detection circuit:

wherein

said switching means is make-and-break means that makes and breaks a feed circuit to and from an open/close driving motor of said throttle valve;

said default mechanism is an initial position return mechanism that returns a throttle valve opening to a predetermined position when said power supply of the motor is interrupted by said switching means;

said first abnormality storage element is arranged so as to store the occurrence of serious abnormality upon occurring the same, interrupt the feed circuit to the motor by said switching means, and at the same time determine an application of said first evacuation operation means to operate said first abnormality alarm display;

said second abnormality storage element is arranged so as to store the occurrence of slight abnormality upon occurring the same, determine the application of said second evacuation operation means, when said first abnormality storage element does not store the occurrence of abnormality, to operate said second abnormality alarm display;

said power supply detection circuit is arranged so as to generate a detection signal upon turning off or on of the power supply switch that conducts the operation and stop of the engine, and reset said first and second abnormality storage element; and

even if the occurrence of abnormality is caused by any temporary noise malfunction, the abnormal state is not reset until the engine is stopped or started again.

5. The engine control system according to claim 3, wherein

said microprocessor is comprised of a main CPU and a sub CPU that are capable of communicating with each other;

said drive control means, fuel injection control means and abnormality detecting means for detecting the serious abnormality or slight abnormality are arbitrarily shared between said main CPU and sub CPU, and at least a part of said abnormality detecting means and drive control means are shared by the respectively different CPUs; and

said accelerator position sensor and throttle position sensor employs a pair of accelerator position sensors and a pair of throttle position sensors respectively so as to be inputted in a distributed manner to said each CPU, and said each CPU, in the case that the detection signal inputted from respective sensors is required at the other CPU, connects in a duplicate manner said sensor output as the input signal of each CPU, or transmits the output to a CPU on the required side.

6. The engine control system according to claim 5, further comprising runaway monitoring means for monitoring the main CPU, runaway monitoring means for monitoring the sub CPU, actuator system error signal output means, both accelerator position sensor abnormality detecting means, and overall control abnormality detecting means:

wherein

said runaway monitoring means for monitoring the main CPU is control abnormality detecting means for detecting said main CPU constituted by a watchdog timer circuit that generates a first reset output for starting again the main CPU when a watchdog signal, being a pulse train generated by said main CPU is inputted, and a pulse width of said watchdog signal exceeds a predetermined value;

said runaway monitoring means for monitoring the sub CPU is the control abnormality detecting means for monitoring the sub CPU that is arranged by said main CPU so as to generate a second reset output for starting again the sub CPU, when the watchdog signal being a pulse train generated by said sub CPU is inputted and the pulse width of said watchdog signal exceeds a predetermined value;

said actuator system error signal output means is detecting means for detecting an actuator system abnormality that is arranged so as to detect a disconnection or a short circuit on said driving motor and the feed circuit thereof to generate an error signal output;

said both accelerator position sensor abnormality detecting means is detecting means for detecting the sensor system abnormality and is arranged so as to generate the error signal output when both of said pair of accelerator position sensors are abnormal;

said synthetic control abnormality detecting means is detecting means for detecting an overall abnormality in the sensor system, the control system and the actuator system and is arranged so as to generate a synthetic error signal output, when the output detected by one of said pair of accelerator position sensors is relatively compared with that from one of said pair of throttle position sensors and it is found by the comparison that a disagreement is excessively large; and

said serious abnormality detecting means is constituted of a logical OR of said first and second reset outputs and said various error signal outputs.

7. The engine control system according to claim 6:

wherein

function of the system is shared such that said drive control means for the driving motor is implemented at either one of said main CPU or sub CPU, and said synthetic control abnormality detecting means is implemented mainly by the other CPU;

said synthetic control abnormality detecting means is dividedly comprised of first half control abnormality detecting means and second half control abnormality detecting means;

said first half control abnormality detecting means is arranged so as to compare whether or not first and second target throttle valve openings calculated at said main CPU and sub CPU based on each sensor output from said pair of accelerator position sensors, are substantially are coincident, and generate a first half error signal output when it is found by the comparison that a disagreement is large;

said second half control abnormality detecting means is arranged so as to compare and determine whether or not a compensation target value assuming a response delay of the throttle valve opening with respect to a target value of the target throttle valve opening on the side of actually controlling said driving motor and an output value from said first or second throttle position sensor are substantially coincident, and generate a second half error signal output when it is determined by the comparison that a disagreement is large; and

said synthetic error signal output is constituted of a logical OR of said first half error signal output and second half signal output.

8. The engine control system according to claim 6, further comprising first and second relative abnormality detecting means, first and second individual abnormality detecting means or/and both throttle position sensor abnormality detecting means each serving as the slight abnormality detecting means, and further comprising fist and second non-defective sensor detecting means:

wherein

said first relative abnormality detecting means is detecting means for mutually comparing the outputs from said pair of accelerator position sensors and generating an error output when a comparative deviation is excessively large;

said second relative abnormality detecting means is detecting means for mutually comparing the outputs from said pair of throttle position sensors, and generating an error output when the comparative deviation is excessively large;

said first individual abnormality detecting means is detecting means for detecting whether or not there is any disconnection or short circuit in each of said pair of accelerator position sensors, and generating an error output when there is any abnormality;

said second individual abnormality detecting means is detecting means for detecting whether or not there is any disconnection or short circuit in each of said pair of throttle position sensors, and generating an error output when there is any abnormality;

said both throttle position sensor abnormality detecting means is detecting means for generating a both error output when both of said pair of throttle position sensors are abnormal;

said slight abnormality detecting means is constituted of a logical OR of said various error outputs or/and both error output;

said first non-defective sensor detecting means is detecting means that, when any relative abnormality is detected by said first relative abnormality detecting means and any disconnection and short circuit abnormality is detected at either one of the accelerator position sensors by said first individual abnormality detecting means, judges the other accelerator position sensor non-defective and selects it;

said second non-defective sensor detecting means is detecting means that, when any relative abnormality is detected by said second relative abnormality detecting means and any disconnection and short circuit abnormality is detected at either one of the throttle position sensors by said second individual abnormality detecting means, determines the other throttle position sensor is non-defective and selects it; and

said non-defective sensor detected by said first and second non-defective sensor detecting means carries out the evacuation operation by said first or second evacuation operation means.

9. The engine control system according to claim 8, further comprising an accelerator switch that performs ON operation when the accelerator pedal is not depressed, and third non-defective sensor detecting means:

wherein

said third non-defective sensor detecting means is detecting means that, when any relative abnormality of a pair of accelerator position sensors is detected by said first relative abnormality detecting means, neither of the accelerator position sensors is determined abnormal due to disconnection or short circuit by said first individual abnormality detecting means, and besides said accelerator switch is under the ON state, determines the accelerator position sensor generating a predetermined detection output is non-defective and selects it, to serve as non-defective sensor detecting means for the accelerator position sensor that is added to said first non-defective sensor detecting means.

10. The engine control system according to claim 8, further comprising throttle valve opening estimate means for calculating a throttle valve opening as a function of engine speed and intake amount, and fourth non-defective detecting means:

wherein

said fourth non-defective sensor detecting means is detecting means that, when any relative abnormality of a pair of the throttle position sensors is detected by said second relative abnormality detecting means and neither of the throttle position sensors is determined abnormal due to disconnection and short circuit by said second individual abnormality detecting means, determines that the throttle position sensor having substantially equivalent detection output to the throttle valve opening estimated by said throttle valve opening estimate means is non-defective, and selects it, to serve as non-defective sensor detecting means for the throttle position sensor that is added to said second non-defective sensor detecting means.

11. The engine control system according to claim 8, further comprising a slightest abnormality operation mode provided in said second evacuation operation means:

wherein

said slightest abnormality operation mode is an operation mode available in the case that although any serious abnormality is not detected, one of a pair of accelerator position sensors or/and one of a pair of throttle position sensors is abnormal; and

engine speed is regulated by said fuel cut control means so that the engine speed set by said first upper limit engine speed threshold setting means may be the upper limit target engine speed, and the evacuation operation at the variable engine speed using the accelerator pedal is performed by said first throttle control means.

12. The engine control system according to claim 8, further comprising a slight abnormality operation mode provided in said second evacuation operation means:

wherein

said slight abnormality operation mode is an operation mode available in the case that any serious abnormality is not detected, at least one of a pair of accelerator position sensors is regarded as being normal, but both of a pair of throttle position sensors are abnormal; and

engine speed is regulated by said fuel cut control means so that the engine speed set by said first upper limit engine speed threshold setting means may be the upper limit target engine speed, and the evacuation operation at the variable engine speed using the accelerator pedal is performed by said second throttle control means.

13. The engine control system according to claim 12, further comprising accelerator return detecting means and idle engine speed threshold setting means both serving as the slight abnormality operation mode provided in said second evacuation operation means:

wherein

said accelerator return detecting means is means for determining that the accelerator pedal is returned when the output detected from said accelerator switch operating so long as the accelerator pedal is not depressed or from a pair of the accelerator position sensors is in the proximity of a predetermined value;

said idle engine speed threshold setting means is means for selecting and setting the target engine speed to the idle engine speed; and

when said accelerator return detecting means detects the return of the accelerator pedal, irrespective of the output from said accelerator position sensor, the throttle valve opening is controlled so that the engine speed detected by said engine speed or vehicle speed detecting means may be a predetermined engine speed set by said idle engine speed threshold setting means.

14. The engine control system according to claim 8, further comprising:

a serious abnormality operation mode provided in said first evacuation operation means;

said serious abnormality operation mode being an operation mode available in the case that at least one of said pair of accelerator position sensors is normal although any serious abnormality is detected;

accelerator return detecting means and idle engine speed threshold setting means;

said accelerator return detecting means being means for determining that the accelerator pedal is returned when an output detected from said accelerator switch operating during the accelerator pedal not being depressed or a pair of accelerator position sensors is in the proximity of a predetermined value;

said idle engine speed threshold setting means being means for setting the target engine speed to the idle engine speed; and

wherein said serious abnormality operation mode controls the engine speed by said fuel cut control means so that the engine speed computed by said first upper limit engine speed threshold computing means may be the target engine speed, and when said accelerator return detecting means detects the return of the accelerator pedal, irrespective of the output from said accelerator position sensor, controls the engine speed by said fuel cut control means so that the engine speed detected by the engine speed detecting means may be a predetermined engine speed set by said idle engine speed threshold setting means, thereby eventually performing the evacuation operation at the variable engine speed using the accelerator pedal.

15. The engine control system according to claim 8, further comprising a most-serious abnormality operation mode provided in said first evacuation operation means:

wherein

said most-serious abnormality operation mode is an operation mode available in the case that the serious abnormality is detected, and moreover both of said pair of accelerator position sensors are abnormal; and

said fuel cut control means performs a fuel injection control so that the target engine speed may be the threshold value computed by said second upper limit engine speed threshold computing means and, when there is no throttle position sensor regarded as non-defective, conducts a fuel injection control by the fuel cut control means so that the target engine speed may be not higher than a predetermined engine speed set by said second upper limit engine speed threshold setting means, thereby eventually performing the evacuation operation by operating the brake pedal with different strength.

16. The engine control system according to claim 15, further comprising a side brake operation detecting switch, idle engine speed threshold setting means and climb rate suppression means each serving as the most-serious abnormality operation mode provided in said first evacuation operation means:

wherein

said side brake operation detecting switch is means for detecting the operation of sub braking means that is added to main braking means operated by said brake pedal;

said idle engine speed threshold setting means is means for setting the target engine speed when said side brake operation detecting switch is operated, to the idle engine speed and controlling the engine speed by said fuel cut control means; and

said climb rate suppression means is means for suppressing the rate of climb of the target engine speed from the engine speed set by said idle engine speed threshold setting means to that set by said second upper limit engine speed threshold computing means or second upper limit threshold setting means when said side brake is released and the operation detecting means is not operated, and by which the engine speed is controlled so as not to rise sharply upon releasing the side brake.

17. The engine control system according to claim 15, further comprising a third alarm and display:

wherein

said third alarm and display alarming and displaying that the evacuation operation is performed by operating the brake pedal with different strength in the most-serious abnormality operation mode within said first evacuation operation means.

18. The engine control system according to claim 15:

wherein

in the most-serious abnormality operation mode in said first evacuation operation means, the non-defective determination of the throttle position sensor and the suppression control of the engine speed due to the fuel cut is performed on the side of the CPU including at least an engine drive control function such as ignition control, fuel injection control or the like, and the evacuation operation can be performed at one of the CPUs irrespective of whether the other CPU is defective or non-defective.