JPH0352999Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic fuel injection device that electronically controls the opening degree of a throttle valve in accordance with the depression angle of an accelerator pedal.

[Conventional technology]

As this type of electronic fuel injection device, one shown in FIG. 4 has been proposed. i.e. accelerator pedal 1
7 is detected by the pedal position detector 1 as an accelerator pedal signal. On the other hand, the valve opening degree of the throttle valve 9 is detected by the valve position detector 2 as a throttle valve signal. The accelerator pedal signal and throttle valve signal detected by these position detectors 1 and 2 are input to the control circuit 10, and the actuator 11 is driven according to the amount of deviation between these two signals. Control circuit 1 by controlling the valve opening
Both input signals of 0 are made equal, that is, the valve opening degree of the throttle valve 9 corresponds to the depression angle of the accelerator pedal 17.
In this manner, this device controls the opening degree of the throttle valve using a servo mechanism.

In such a device, the actuator 11 may fail for some reason, or the throttle valve 9 may malfunction, making it impossible to control the opening of the throttle valve 9 in response to the accelerator pedal signal. be. If the throttle valve 9 remains in the fully open position due to such a failure, the vehicle speed will increase, which is dangerous if the vehicle is running, and the engine rotational speed will increase if the vehicle is stopped. will rise and there is a danger that the engine will be destroyed.

Therefore, an electronic fuel injection system has been proposed that is equipped with a fail-safe device to prevent such a dangerous situation. FIG. 3 shows a conventional structure of such a fail-safe device. In the figure, an accelerator pedal signal V _a from a pedal position detector 1 and a throttle valve signal V b from a valve position detector 2 _.
is supplied to the differential amplifier 3, and these two signals V _a ,
Deviations in V _b are detected. If the gain for each input of the differential amplifier 3 is R ₂ /R ₁ , then the differential amplifier 3
The output V ₁ of is R ₂ /R ₁ (V _b −V _a ). This deviation signal V ₁ is full-wave rectified by a full-wave rectifier circuit 4, and an absolute value signal V ₂ of the deviation signal V ₁ is obtained.

The absolute value signal V ₂ of this deviation is the set value by comparator 5.
It is compared with _VR , and if it is higher than _VR , the output of comparator 5 becomes low level L and is detected. When the comparator 5 detects that the deviation absolute value signal V ₂ is greater than or equal to the set value _VR , and this detection state continues for a set time _{TR or} longer, the set time detection circuit 6 detects this.
For example, the output of the comparator 5 is input to the counter CT and each clear terminal CL of the D-type flip-flop FF. A clock signal is input from the clock oscillator CL to the clock terminal CL of the counter CT.
A high level H is applied to the data terminal D of the D-type flip-flop FF, and a counter signal is applied to the clock terminal CL.
The set count value output of CT is supplied.

While the output of comparator 5 is at H level, counter CT,
The flip-flop FF is in a clear state,
The Q output of the flip-flop FF outputs a low level. However, when the deviation becomes larger than the absolute value _VR , the counter CT is cleared and starts counting the clocks of the clock oscillator CK, and the flip-flop FF is also cleared. Therefore, when the counter CT counts the clock to the set value, a high level H is set in the flip-flop FF by the output of the counter CT, and the high level H is set in the flip-flop FF.
The Q output of becomes high level, and the time during which the absolute value of deviation V ₂ is greater than or equal to the set value V _R is greater than or equal to the set time T _R , which means that this electronic fuel injection device has become abnormal. Detected.

The abnormality detection output from the set time detection circuit 6 is input to the stop circuit 7, and fuel injection is stopped.
In other words, when the output of the flip-flop FF becomes high level, the output makes the transistor Q conductive, and the relay inserted in series with the transistor Q becomes conductive.
RL ₁ operates and its junction SW ₁ is turned off. A main relay RL ₂ is connected between the terminal T connected to the battery of the vehicle and ground via a contact SW ₁ , and the contact SW ₂ of this relay RL ₂ is connected to the terminal T and the operating power source of the control circuit 8 of the fuel injection device. inserted between the terminals. Therefore, when an abnormality is detected in the time detection circuit 6, relay RL ₁ operates, and its relay contact SW ₁ interrupts the operating circuit of relay RL ₂ , causing the relay contact to close.
SW ₂ is turned off, the control circuit 8 becomes inoperable, and fuel injection is stopped. The stop circuit 7 may stop the ignition of the engine instead of stopping the fuel injection based on the abnormality detection output.

In the normal state, the opening and closing of the throttle valve 9 is controlled by the device shown in FIG.

In this way, conventional fail-safe circuits detect when the deviation between the accelerator pedal signal and the throttle valve signal exceeds a set value, and the time that the difference continues to exceed the set value exceeds the set time. The detection output is configured to stop fuel injection or engine ignition.

[Problem that the invention attempts to solve]

In such a conventional configuration, when the battery voltage is reduced, sufficient drive current is no longer supplied to the actuator 11, making it impossible to open and close the throttle valve 9 in accordance with the depression angle of the accelerator pedal 17. . Therefore, the amount of deviation between the accelerator pedal signal from the pedal position detector 1 and the throttle valve signal from the valve position detector 2 may exceed the set value _VR given to the comparator 5. When this state continues for a set time T _R or more, the set time detection circuit 6 generates an abnormality detection output, drives the stop circuit 7, and stops fuel injection or engine ignition.

Such a decrease in battery voltage occurs, for example, when starting the vehicle in cold weather or due to the life of the battery. Under such conditions, when the accelerator pedal 17 is depressed beyond a certain level, the throttle valve 9 detects the pedal position detector of the accelerator pedal 17. 1 becomes impossible to follow, and a deviation amount exceeding the set value occurs.
Therefore, the fuel injection device control circuit 8 becomes inoperable, stopping fuel injection or ignition of the engine, making it impossible to drive the vehicle.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic fuel injection device that prevents fuel injection or engine ignition from being stopped even when a sufficient drive current is not supplied to the actuator.

[Means for solving problems]

This invention was created to solve the above problems.
A pedal position detector detects the depression angle of the accelerator pedal as an accelerator pedal signal, a valve position detector detects the valve opening of the throttle valve as a throttle valve signal, and each of the signals is input to a control circuit, An actuator is driven by the output of the control circuit, and the actuator controls the opening degree of the throttle valve to a value corresponding to the depression angle, and the deviation amount between the accelerator pedal signal and the throttle valve signal is set to a set value. In addition, a detection means for detecting that the temperature exceeds a set value continues for a set time or more, and a stop means for stopping fuel injection or engine ignition based on the output of the detection means are provided, and the actuator is locked. is detected by the detection means to drive the stop means, the electronic fuel injection device comprising a current detection means for detecting a drive current of the actuator, and a maximum load of the actuator when the throttle valve is driven. a comparator that compares the output from the current detection means with a current value for obtaining the required torque or a set value corresponding to a current value of ±α; When it is determined that the amount of deviation is equal to or less than the set value corresponding to the value, the stopping means is made inoperable even if the deviation amount is equal to or greater than the set value and is longer than the set time.

[Effect]

In the above configuration, when the drive current of the actuator is larger than the current value for obtaining the necessary torque at maximum load when driving the throttle valve or the set value corresponding to the current value of ±α, the comparator determines this and detects this. When the means detects that the deviation amount is greater than a set value and continues for more than a set time, the fuel injection or engine ignition that drives the stop means is stopped.

On the other hand, when the drive current of the actuator is smaller than the current value for obtaining the necessary torque at the maximum load or the set value corresponding to the current value of ±α, the comparator determines this state and the deviation amount is greater than or equal to the set value. and the stopping means is made inoperative even if it continues for a set time or longer. Therefore, in such a state, fuel injection or engine ignition is not stopped regardless of the amount of deviation.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, the same parts as in FIG. 3 are denoted by the same reference numerals. The actuator 11 is provided with a throttle valve driving motor M driven by the driving transistor 13 of the control circuit 10, and the driving current flowing through the motor M is converted into a voltage by the resistor _R3 of the current detection circuit 14. Convert and detect. This detection voltage is applied to the negative phase input of the comparator 15. Further, a reference set value V _R ' is applied to the positive phase input. The set value V _R ′ corresponds to a current value or a predetermined current value of ±α to obtain the necessary torque for the maximum load when the actuator 11 is operating the throttle valve, that is, the load when the throttle valve is fully open. set to the value. Furthermore, the control circuit 10
detects the voltage of resistor R ₃ and activates actuator 11.
An overcurrent protection circuit 12 is provided to protect the overcurrent flowing through the motor _M when the motor M is mechanically locked. ) or more torque is generated in the motor M, and the value is set to such a value that failure will not occur even if the motor M and the driving transistor 13 are continuously supplied with current. The outputs of the comparators 5 and 15 are input to the OR circuit 16, and the output is sent to the counter CT in the set time detection circuit 6.
and is input to the clear terminal CL of flip-flop FF. Note that the reference value V _R ′ corresponding to the predetermined current value set in the comparator 15 is smaller than the reference value V _R ″ corresponding to the set current value I _R set in the overcurrent protection circuit 12.

In this configuration, when the battery voltage is normal, a sufficient drive current can flow through the motor M, so the actuator 11 controls the throttle valve 9 in accordance with the accelerator pedal signal from the pedal position detector 1. , this can be fully opened. Therefore, the amount of deviation between the accelerator pedal signal and the throttle valve signal at this time becomes zero, and the output of the comparator 5 becomes H level and is sent to the counter CT and the flip-flop through the OR circuit 16.
Since the signal is input to the clear terminal CL of the FF, the set time detection circuit 6 does not operate. Also, actuator 1
1 is mechanically locked, an overcurrent flows through the motor M, so the resistor _R3 detects this and activates the overcurrent protection circuit 12, changing the current of the motor M to the current set by the circuit 12. Limit to the value I _R. At this time, as described above, the reference value V _R ′ set in the comparator 15 is smaller than the reference value V _R ″ corresponding to the motor current value I _R limited by the overcurrent protection circuit 12. , the comparator 15 outputs L. Furthermore, a deviation occurs between the accelerator pedal signal and the throttle valve signal, and this deviation amount is outputted by the comparator 5.
When the value reaches or exceeds the set value V _R set in , the output becomes L level, clearing of the counter CT and flip-flop FF is canceled via the OR circuit 16, and the set time detection circuit 6 is activated. When the circuit 6 continues to operate for a set time T _R or more, it outputs a detection signal to the stop circuit 7, turns on the transistor Q, and disables the control circuit 8, thereby stopping fuel injection or engine ignition. urge

On the other hand, when the battery voltage is low, sufficient drive current cannot flow through the motor M, and the torque of the motor M generated at this time is greater than the opening of the throttle valve 9 at the load amount corresponding to the torque. Throttle valve 9 cannot be opened.
In such a state, when the accelerator pedal 17 is depressed in an attempt to open the throttle valve 9 beyond the opening degree, a deviation occurs between the accelerator pedal signal and the throttle valve signal, and when the amount of deviation exceeds the set value _VR , the comparison is made. The output of the device 5 becomes L level. However, the current detection circuit 14 monitors the drive current of the motor M, and the voltage corresponding to the drive current obtained from the resistor R ₃ is compared with the set value V _R ' by the comparator 15. As mentioned above, this set value V _R ' is a current value or a current value of ±α to obtain the necessary torque for the maximum load when the actuator 11 is operating the throttle valve, and is set by the overcurrent protection circuit 12. A value corresponding to a current value slightly smaller than the current value I _R is set. Therefore, when the battery voltage is low, a current corresponding to the torque at maximum load cannot flow, so the output of the comparator 15 remains at the H level, and the output of the OR circuit 16 remains at the H level. Therefore, both the counter CT and the flip-flop FF are reset, and the set time detection circuit 6 becomes inactive. Furthermore, since the current of the motor M is less than the set value I _R set in the overcurrent protection circuit 12, the circuit 12 is also inoperative. Therefore, even if the deviation amount exceeds the set value V _R in such a state and continues for more than the set time T _R , the stop circuit 7 will not be driven and fuel injection or engine ignition will not be stopped, so the vehicle cannot continue to run. can.

That is, when a deviation occurs and the current of the motor M is larger than the current value corresponding to the set value V _R ' of the current detection circuit 14, it is determined that the actuator 11 is mechanically locked, and the overcurrent protection circuit is activated. 1
When the current value is smaller than the current value I _R set at 2, it is determined that the actuator 11 is not mechanically locked but that the battery power supply voltage is decreasing.

When the battery voltage is low, the throttle valve is opened as much as possible without stopping fuel injection or engine ignition even if the accelerator pedal signal and throttle signal continue to differ by more than the set value. I'm trying to do that.

It is possible that the actuator 11 may mechanically lock when the battery voltage is low, but the battery voltage decreases in this way when starting the engine in cold weather, and even if the battery voltage were to lock, the engine would not start. As soon as the engine is started, the battery voltage returns to normal and the stop circuit 7 is activated, so there is no problem in terms of safety.

〔effect〕

As described above, according to the present invention, the drive current of the actuator is adjusted to the current value or ±α to obtain the torque at the maximum load when driving the throttle valve.
When the setting value is smaller than the corresponding setting value,
Since the stopping means is made inoperative regardless of the amount of deviation, the vehicle can be driven safely.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are a block diagram and a circuit diagram respectively showing an embodiment of the fail-safe device according to the present invention;
FIG. 3 is a block diagram showing a conventional fail-safe device, and FIG. 4 is a block diagram showing the present invention and a conventional fuel injection device. 1... Pedal position detector, 2... Valve position detector, 3... Differential amplifier, 5, 15... Comparator,
6...Setting time detection circuit, 7...Stop circuit, 9...
... Throttle valve, 10... Control circuit, 11...
...actuator, 12...overcurrent protection circuit, 1
4...Current detection circuit, 16...OR circuit, M...
Throttle valve drive motor.

Claims (1)

[Claims for Utility Model Registration] The depression angle of the accelerator pedal is detected as an accelerator pedal signal by a pedal position detector, the valve opening of the throttle valve is detected as a throttle valve signal by a valve position detector, and each of the above-mentioned signals are input into a control circuit, and the output of the control circuit drives an actuator, and the actuator controls the opening degree of the throttle valve to a value corresponding to the depression angle. The actuator is provided with a detection means for detecting that the amount of deviation from the signal is greater than a set value and continues for more than a set time, and a stop means for stopping fuel injection or engine ignition based on the output of the detection means. The electronic fuel injection device is configured such that the detecting means detects a locked state of the throttle valve and drives the stopping means, the electronic fuel injection device comprising: a current detecting means for detecting a drive current of the actuator; a comparator that compares the output from the current detection means with a current value for obtaining the required torque at the maximum load or a set value corresponding to a current value of ±α, and the comparator compares the drive current of the actuator with a set value corresponding to a current value of ±α. is characterized in that when it is determined that the amount of deviation is equal to or less than a set value corresponding to the current value, the stopping means is made inoperable even if the deviation amount is equal to or greater than the set value and is longer than the set time. electronic fuel injection system.