Vehicle engine control device

• US 20040002808A1
• Filed: 11/20/2002
• Published: 01/01/2004
• Est. Priority Date: 06/26/2002
• 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 6,751,544 B2
• Time in Patent Office: Days
• US Class Current: 701/107
• 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 31/009 for maximum speed control

Abstract

Escape running performance at the time of the occurrence of an abnormality in an electronic throttle control system is improved. At the time of the occurrence of a severe abnormality, an abnormality storage element is operated, and an electric supply load relay of a throttle valve driving motor is de-energized to return a throttle valve to the default, and further, an alarm display is actuated, and an upper limit engine rotational speed is suppressed by control of a fuel injection valve, and escape running is carried out. As a suppression rotational speed, a lower limit threshold at a stop, a rotational speed substantially in proportion to the output of an accelerator position sensor, a rotational speed substantially in inverse proportion to the output of a throttle position sensor, or a default threshold rotational speed is selected, and multiple escape running can be carried out.

Claims

1. A vehicle engine control device comprising a transmission in which at least a forward position, a reverse position, a neutral position, and a parking position can be selected by an operation of a selector lever, wherein

the control device includes a microprocessor, is constructed to receive electric supply from an on-vehicle battery through a power source switch, and includes engine rotational speed detection means for detecting a rotational speed of an engine, fuel injection means for supplying a fuel to the engine, a pair of accelerator position sensors for detecting a depression degree of an accelerator pedal, a pair of throttle position sensors for detecting a throttle valve opening degree of an intake throttle valve of the engine, a driving motor for carrying out an opening and closing control of the intake throttle valve in accordance with outputs of the pair of accelerator position sensors and the pair of throttle position sensors, a motor power source switching element for controlling electric supply to the driving motor, a default position return mechanism for returning the throttle valve opening degree to a default position for escape driving when the motor power source switching element breaks electric supply, and drive control means for the driving motor, and further includes abnormality detection means, an abnormality storage element, lower limit rotation threshold setting means, automatic shift escape running means, and selective shift escape running means,

the abnormality detection means is means for always monitoring operations of a sensor system, a control system, and an actuator system relating to control of the intake throttle valve, detecting whether the intake throttle valve can be controlled, and generating a severe abnormality detection output when the intake throttle valve can not be controlled,

when the abnormality detection means generates the severe abnormality detection output, the abnormality storage element stores this, breaks the motor power source switching element to stop electric supply to the driving motor, and is constructed such that its storage state is reset in at least one of closing and breaking of the power source switch,

the lower limit rotation threshold setting means is means for setting a lower limit rotational speed at which the engine can continue to rotate,

the automatic shift escape running means is means for controlling an engine rotational speed by the fuel injection control means in such a way that when electric supply to the driving motor is stopped, the engine rotational speed detected by the rotational speed detection means of the engine becomes a rotational speed less than a predetermined limiting rotational speed, and becomes a rotational speed greater than a minimum engine rotational speed set by the lower limit rotation threshold setting means, and

the selective shift escape running means is means for controlling the engine rotational speed by the fuel injection control means in such a way that when there is an accelerator position sensor regarded as being normal after electric supply to the driving motor is stopped and the transmission is once selected to be put in the parking position, the engine rotational speed detected by the engine rotational speed detection means becomes a rotational speed less than a variable threshold rotational speed of a value substantially in proportion to the depression degree of the accelerator pedal set by variable threshold rotation setting means, and becomes a rotational speed greater than a minimum engine rotational speed set by the lower limit rotation threshold setting means.

2. The vehicle engine control device according to claim 1, wherein the automatic shift escape running means includes calculation threshold setting means and default rotation threshold setting means as setting means for setting the predetermined limiting rotational speed,

although there is no accelerator position sensor regarded as being normal, when a throttle position sensor regarded as being normal exists, the calculation threshold setting means is means for setting an upper limit rotational speed of a value substantially in inverse proportion to an output of the throttle position sensor generating a predetermined output corresponding to a throttle valve opening degree of a throttle valve in which an opening and closing operation is stopped and a present position is unspecified, and

the default rotational speed setting means is means for setting an upper limit rotational speed higher than the lower limit rotational speed when there is no throttle position sensor regarded as being a non-defective unit.

3. The vehicle engine control device according to claim 1, further comprising driving intention confirmation means, wherein the driving intention confirmation means is means for judging that there is a driving intention in a case where after the abnormality storage element carries out an abnormality storage operation, brakes to a vehicle are released and the accelerator pedal is depressed, and judging that there is a stop intention in at least one of a case where the brakes to the vehicle are actuated and a case where the accelerator pedal is returned, and when a judgment of the stop intention is made, the engine rotational speed is controlled by the fuel injection control means so that the engine rotational speed becomes substantially equal to the engine rotational speed set by the lower limit rotation threshold setting means.

4. The vehicle engine control device according to claim 1, further comprising rising rate suppression means, wherein the rising rate suppression means is means for suppressing a sudden rise of an objective engine rotational speed in at least one of a case where the lower limit rotational speed is changed over to one of the predetermined limiting rotation speed and the variable threshold rotational speed, and a case where the default rotational speed is changed over to the calculation threshold rotational speed.

5. The vehicle engine control device according to claim 1, further comprising a first alarm display and first discrimination operation control means, wherein the first alarm display operates when the abnormality storage element stores a severe abnormality state, the discrimination operation control means is means for carrying out a discrimination operation to drive the first alarm display to flash when there is no accelerator position sensor regarded as being a non-defective unit, and an alarm display is carried out to indicate that escape running does not depend on depression of the accelerator pedal and a driving speed of the vehicle must be adjusted by an operation of the brake pedal.

6. The vehicle engine control device according to claim 3, wherein at least one of an accelerator switch and accelerator return detection means is provided, as means for detecting depression of the accelerator pedal, for the driving intention confirmation means.

7. The vehicle engine control device according to claim 6, wherein the accelerator return detection means is means for detecting that outputs of both the pair of accelerator position sensors regarded as being non-defective units are at predetermined return positions.

8. The vehicle engine control device according to claim 3, wherein a brake release switch and transmission selection position confirmation means are provided for the driving intention confirmation means, the brake release switch is means linked with at least one control operation of a main braking operation by a foot brake pedal and a sub-braking operation by a side brake for holding a vehicle stop, it is judged by an operation of the brake release switch that there is a driving intention, and the transmission selection position confirmation means is means for enabling, when a specified position of the forward position is selected after occurrence of an abnormality and after the parking position is once selected, at least one of the default rotation threshold setting means and the calculation threshold rotation setting means even in a state where the brake release switch is in a state of a braking operation.

9. The vehicle engine control device according to claim 1, wherein

the abnormality detection means includes at least one of runaway monitor means of the microprocessor, error signal output means of a driving motor system, both abnormality detection means of the pair of accelerator position sensors, and abnormality deviation detection means,

the runaway monitor means of the microprocessor is abnormality detection means of the control system, constituted by a watch dog timer circuit to which a watch dog signal as a pulse train generated by the microprocessor is inputted, and which generates a reset output for restarting the microprocessor when a pulse width of the watch dog signal exceeds a predetermined value,

the error signal output means of the driving motor system is abnormality detection means of the actuator system, constructed to detect at least one of a disconnection and a short circuit for the driving motor and its feeding circuit, and to generate a first error signal output,

the both abnormality detection means is abnormality detection means of the sensor system, constructed to generate a second error signal output when the pair of accelerator position sensors are abnormal,

the abnormality deviation detection means is abnormality detection means of all of the sensor system, the control system and the actuator system, which is constructed to compare an objective throttle valve opening degree corresponding to a detection output of one of the pair of accelerator position sensors with an actual throttle valve opening degree detected by the throttle position sensor, and to generate a third error signal output when comparison inconsistence is excessively large, and

the abnormality detection means generates the severe abnormality detection output by a logical sum of at least part of the reset output, the first error signal output, the second error signal output, and the third error signal output.

10. The vehicle engine control device according to claim 9, wherein dynamic abnormality detection means is provided as the abnormality detection means, the dynamic abnormality detection means is means for detecting that both the pair of throttle position sensors have become abnormal when the transmission selects one of the forward position and the reverse position, and a severe abnormality is released by selecting the parking position in the transmission after the abnormality occurs.

11. The vehicle engine control device according to claim 9, wherein default return abnormality detection means is provided as the abnormality detection means, the default return abnormality detection means is abnormality detection means of the actuator system, is constructed to detect that in a state where electric supply to the driving motor is switched off by the motor power source switching element, detection outputs of the pair of throttle position sensors are differed from a predetermined value corresponding to a default return position, and to generate a fourth error signal output.

12. A vehicle engine control device comprising a transmission in which at least a forward position, a reverse position, a neutral position, and a parking position can be selected by an operation of a selector lever, wherein

the control device includes a microprocessor, is constructed so as to receive electric supply from an on-vehicle battery through a power supply switch, and includes engine rotational speed detection means for detecting a rotational speed of an engine, fuel injection means for supplying a fuel to the engine, a pair of accelerator position sensors for detecting a depression degree of an accelerator pedal, a pair of throttle position sensors for detecting a throttle valve opening degree of the engine, and drive control means for controlling a driving motor which carries out an opening and closing control of an intake throttle valve in accordance with outputs of the pair of accelerator position sensors and the pair of throttle position sensors, and further includes first non-defective sensor detection means, second non-defective sensor detection means, and escape running means,

the first non-defective sensor detection means includes first relative abnormality detection means for generating a relative error output when outputs of the pair of accelerator position sensors are mutually compared and a comparison deviation is excessive, and first individual abnormality detection means for detecting existence of a disconnection and a short circuit for each of the pair of accelerator position sensors and generating an individual error output when an abnormality exists, and is means for making a non-defective judgment in such a manner that when both of the pair of accelerator position sensors are not in at least one state of the disconnection and the short circuit, and a relative abnormality does not occur, both the accelerator position sensors are regarded as being non-defective units, and even if the relative abnormality occurs, when one of the accelerator position sensors is in the one state of the disconnection and the short circuit, the other accelerator position sensor is regarded as being a non-defective unit,

the second non-defective sensor detection means includes second relative abnormality detection means for outputting a relative error output when outputs of the pair of throttle position sensors are mutually compared and a comparison deviation is excessive, and second individual abnormality detection means for detecting existence of a disconnection and a short circuit of each of the pair of throttle position sensors and generating an individual error output when an abnormality exists, and is made means for making a non-defective judgment of the throttle position sensors in such a manner that when both of the pair of throttle position sensors are not in a state of the disconnection and the short circuit, and a relative abnormality does not occur, both the throttle position sensors are regarded as being non-defective units, and even if the relative abnormality occurs, when one of the throttle position sensors is in the state of the disconnection and the short circuit, the other throttle position sensor is regarded as being a non-defective unit, and

the escape running means is means for carrying out escape driving by the drive control means and the fuel injection control means in response to at least one abnormality of a slightest abnormality due to at least one of a single abnormality of the pair of accelerator position sensors and a single abnormality of the pair of throttle position sensors, a slight abnormality due to both abnormality of the pair of throttle position sensors, and a severe abnormality due to both abnormality of the pair of accelerator position sensors.

13. The vehicle engine control device according to claim 12, further comprising an accelerator switch and third non-defective sensor detection means, wherein

the accelerator switch is a switch for detecting that the accelerator pedal is not depressed, and

the third non-defective sensor detection means is means for judging an accelerator position sensor generating a predetermined detection output to be a non-defective unit and selecting it in a case where the relative abnormality of the pair of accelerator position sensors is detected by the first relative abnormality detection means, it is judged by the first individual abnormality detection means that no accelerator position sensor suffers from the disconnection and the short circuit abnormality, and the accelerator switch detects return of the accelerator pedal.

14. The vehicle engine control device according to claim 12, further comprising throttle valve opening degree estimation means and fourth non-defective sensor detection means, wherein

the throttle valve opening degree estimation means is means for estimating a throttle valve opening degree on the basis of the engine rotational speed detected by the engine rotational speed detection sensor, an air supply amount detected by an air supply amount detection sensor, and a characteristic map including the engine rotational speed, the air supply amount, and the throttle valve opening degree, and

the fourth non-defective sensor detection means is means for judging a throttle position sensor having substantially the same detection output as the throttle valve opening degree estimated by the throttle valve opening degree estimation means to be a non-defective unit and selecting it when the relative abnormality of the pair of throttle position sensors is detected by the second relative abnormality detection means and when it is judged by the second individual abnormality detection means that no throttle position sensor suffers from the disconnection and the short circuit abnormality.

15. The vehicle engine control device according to claim 12, further comprising a default position return mechanism and fifth non-defective sensor detection means, wherein

the default position return mechanism is a mechanism for automatically returning the throttle valve opening degree to a predetermined opening degree suitable for escape running when a power source of the driving motor of the throttle valve is switched off, and

the fifth non-defective sensor detection means is means for judging a throttle position sensor having a detection output almost equal to a throttle valve opening degree corresponding to a predetermined default return position to be a non-defective unit and selecting it in a state where the relative abnormality of the pair of throttle position sensors is detected by the second relative abnormality detection means, it is judged by the second individual abnormality means that no throttle position sensor suffers from the disconnection and the short circuit abnormality, and a power source of the driving motor is switched off by the motor power source switching element.

16. The vehicle engine control device according to claim 12, wherein a slightest abnormality driving mode is provided in the escape running means, the slightest abnormality driving mode is a driving mode for a slightest abnormality in at least one of a single abnormality of the pair of accelerator position sensors and a single abnormality of the pair of throttle position sensors, in which a severe abnormality is not detected and an opening and closing control of the throttle valve can be carried out by the driving motor,

the control device includes upper limit rotation threshold setting means and first throttle escape control means in relation to the slightest abnormality driving mode,

the upper limit rotation threshold setting means is means for setting a predetermined engine rotational speed lower than an allowable maximum rotational speed of the engine, close to a rotational speed at which the engine can generate maximum output torque, and not higher than a predetermined rotational speed,

the first throttle escape mode control means is means for drive-controlling the driving motor so that an objective throttle valve opening degree corresponding to an output of an accelerator position sensor regarded as being a non-defective unit substantially coincides with an output of a throttle position sensor regarded as being a non-defective unit, and

in the slightest abnormality driving mode, limitations are put so that the engine rotational speed becomes a predetermined value or lower by the fuel injection control means and the upper threshold setting means, and escape running is carried out by the drive control means within a throttle valve opening degree range substantially equal to that at a normal driving time.

17. The vehicle engine control device according to claim 12, wherein a slight abnormality driving mode is provided in the escape running means, the slight abnormality driving mode is a driving mode for a slight abnormality in a case where although both the pair of accelerator position sensors are abnormal, a severe abnormality is not detected, at least one of the pair of accelerator position sensors is normal, and an opening and closing control of the throttle valve can be carried out by the driving motor,

the control device further includes upper limit rotation threshold setting means and second throttle escape control means in relation to the slight abnormality driving mode,

the upper limit rotation threshold setting means is means for setting a predetermined engine rotational speed lower than an allowable maximum rotational speed of the engine, close to a rotational speed at which the engine can generate maximum output torque, and not higher than a predetermined rotational speed,

the second throttle escape running control means is means for drive-controlling the driving motor so that at least one control of a control for making a detected engine rotational speed substantially coincident with an objective engine rotational speed corresponding to an output of an accelerator position sensor regarded as being a non-defective unit, and a control for making a detected vehicle speed substantially coincident with an objective vehicle speed corresponding to an output of an accelerator position sensor regarded as being a non-defective unit, and

in the slight abnormality driving mode, although limitations are put so that the engine rotational speed becomes a predetermined value or lower by the fuel injection control means and the upper threshold setting means, escape running is carried out by the drive control means within a throttle valve opening degree range substantially equal to that at a normal driving time.

18. The vehicle engine control device according to claim 17, wherein escape mode selection means is provided for the slight escape driving mode,

the escape mode selection means is means for enabling the slight escape driving at at least one of a time when a selection position of the transmission is selected to the parking position after occurrence of the slight abnormality, and a time when an escape mode selection switch is manually closed,

in a case where a constant speed mode selection switch is provided, selection of the objective engine rotational speed and the objective vehicle speed is enabled by an operation of the constant speed mode selection switch, and

in a case where the constant speed mode selection switch is not provided, only the objective engine rotational speed is made effective.

19. The vehicle engine control device according to claim 17, wherein smooth shift correction means is provided for the slight escape driving mode, and the smooth shift correction means corrects one of the objective engine rotational speed and the objective vehicle speed so that an objective value is not suddenly changed but is gently changed.

20. The vehicle engine control device according to claim 16, further comprising a second alarm display and second discrimination operation control means, the second alarm display operates at least one of a single abnormality of the pair of accelerator position sensors and a single abnormality of the pair of throttle position sensors though a severe abnormality does not occur, the second discrimination operation control means is means for carrying out a discrimination operation to drive the second alarm display to flash when there is no throttle position sensor regarded as being a non-defective unit, and an alarm and display is given to a driver by discriminating through the second alarm display whether escaping running presently carried out is escape running by the first throttle escape mode control means or escape running by the second throttle escape control means.

21. A vehicle engine control device using a microprocessor and controlling a driving motor for carrying out an opening and closing control of an intake throttle valve of an engine in accordance with outputs of a pair of accelerator position sensors for detecting a depression degree of an accelerator pedal and outputs of a pair of throttle position sensors for detecting a throttle valve opening degree, the control device including engine rotational speed detection means for detecting a rotational speed of the engine and fuel injection control means for the engine, and further including abnormality detection means, escape running means, and rest cylinder control means, wherein

the abnormality detection means is means for always monitoring operations of a sensor system, a control system, and an actuator system relating to control of the throttle valve, discriminating between a severe abnormality in which control of the throttle valve is impossible, and a slight abnormality in which control of the throttle valve is possible, and detecting it,

the escape running means includes at least one of severe abnormality escape running means for controlling the rotational speed of the engine by stopping the control of the throttle valve and by the fuel injection control means, and slight abnormality escape running means for suppressing the rotational speed of the engine by the fuel injection control means while carrying out the control of the throttle valve, and

the rest cylinder control means is speed control means for increasing or decreasing the number of rest cylinders in which fuel injection is stopped, in accordance with a magnitude of a relative speed deviation between an objective engine rotational speed and an engine rotational speed detected by the engine rotational speed detection means, to obtain the engine rotational speed substantially equal to the objective engine rotational speed.

22. The vehicle engine control device according to claim 21, wherein auxiliary control means is provided for the rest cylinder control means, and the auxiliary control means is means for carrying out at least one of increase and decrease of an injection fuel and increase and decrease of an ignition advance before the number of effective cylinders is increased and decreased by the rest cylinder control means, and carrying out increase and decrease of the number of effective cylinders when the increase and decrease control exceeds an allowable limitation.

23. The vehicle engine control device according to claim 21, further comprising upper limit rotation threshold setting means and fuel cut means, the upper rotation threshold setting means is means for setting an upper limit rotational speed to immediately stop all cylinders irrespective of a magnitude of the relative speed deviation and existence of an allowance in the number of rest cylinders, and the fuel cut means is means for stopping fuel injection to all cylinders to stop the engine when the rotational speed of the engine exceeds the engine rotational speed set by the upper limit rotation threshold setting means.

24. The vehicle engine control device according to claim 21, further comprising driving intention confirmation means, lower limit rotation threshold setting means, and lower limit rotational speed correction means, wherein

the driving intention confirmation means is means for judging whether a driver has an intention to carry out escape running, on the basis of at least one of a select position of a transmission, existence of a braking operation to a vehicle, and existence of an operation of an accelerator pedal,

the lower limit rotation threshold setting means is means for setting a minimum engine rotational speed at which rotation can be continued,

when the drive intention confirmation means makes a judgment of existence of a stop intention, the lower limit rotational speed correction means is means for increasing or decreasing the engine rotational speed set by the lower limit rotation threshold setting means in accordance with environmental conditions including cooling water temperature of the engine and a working state of an air conditioner, and

when the lower limit rotation threshold setting means is applied, at least one of the rest cylinder control means and the auxiliary control means carries out an injection control of fuel so that an actual engine rotational speed becomes almost equal to the lower limit rotational speed set by the lower limit rotation threshold setting means.