JPS61104144A - Control device for engine - Google Patents

Abstract

PURPOSE:To enable only a normal air flow rate signal to be used, by a method wherein, in a heat type air flow rate measuring device, when noise component is mixed in a signal for starting of energizing to a temperature sensitive element, an output signal due to the noise signal is eliminated. CONSTITUTION:A temperature sensitive element 12 and an auxiliary temperature sensitive element 13 are located to the interior of an intake air pipe 11 through which intake air is fed to an engine. A series circuit containing each of the elements 12 and 13 forms one branch of a bridge circuit. A heating power is fed through a transistor 17 to a connection between the elements 12 and 13 serving as the input terminal of the bridge circuit. The output terminal part of the bridge circuit, i.e., a connection point between the element 12 and a resistor 14 and a connection point between resistors 15 and 16 are connected to a comparator 18 to compare voltages, fed to the two output terminal parts, with each other. An air temperature measured by the element 13 is set such that an output signal from the comparator 18 rises under a state in that the temperature of the element 12 is increased to a specified temperature state. The output signal resets a flip flop circuit 19 for control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention provides, for example, an engine with an air-fuel ratio of 111
The present invention relates to an engine control device equipped with a means for measuring the flow rate of air flowing into an intake pipe so as to be effectively used as a sensor mechanism for detecting the operating state of the engine in a case where the engine is operated under the following conditions.

[Background Art] When electronically controlling the air-fuel ratio of an engine, the operating state of the engine is constantly monitored and a signal corresponding to the operating state is detected, and based on this detection signal, for example, the fuel injection amount and ignition for the engine are controlled. It calculates the timing, etc., and executes fuel injection amount control and ignition timing control based on the calculation results.

As means for monitoring the operating state of the engine, there are engine rotational speed detection sensors, engine cold water flow detection sensors, throttle opening sensors, etc.; As related,
Air flow measuring devices exist that measure and detect intake air flow.

As a means for measuring the amount of intake air, a thermal air flow rate measuring device that utilizes the heat dissipation effect of airflow is known, for example, as disclosed in Japanese Patent Laid-Open No. 55-104538. In other words, a temperature-sensing element made of a resistor whose resistance value changes depending on temperature is set in the intake pipe, and a heating current is supplied to this temperature-sensing element to measure its temperature change state. , so that the temperature of the temperature sensing element is controlled to a specified temperature state.
The heating current is feedback-controlled. Therefore, the amount of air flowing into the intake pipe can be measured from the state of this heating current.

However, in a configuration in which the temperature sensing element is heated to a constant temperature state by an analog-controlled current, the temperature is about 2 times higher than the air flow rate, which changes by a factor of 100. It only changes by a factor of two, and its measurement sensitivity is extremely low.

Therefore, in order to use this air flow sensor for controlling an internal combustion engine, it is necessary to provide an offset processing means for the detection signal amplification circuit, and the control circuit for this purpose tends to become complicated.

Furthermore, when configuring an engine control device using a microcomputer, it is necessary to convert analog output signals from sensors into digital signals, and in this case, high-precision A/D conversion must be performed. No. That is, a high-resolution A/D converter and an extremely high-precision reference voltage power source for this A/D converter are required.

[Problem to be Solved by the Invention 1] This invention has been made in view of the above-mentioned points, and it is possible to set the measurement detection sensitivity of the amount of intake air taken into the engine to a sufficiently good state. .

At the same time, it is possible to obtain a detection signal in the state that best matches the operating state of the engine.
The present invention aims to provide an engine control device that does not require a circuit system such as a D converter.

Further, in the engine control device according to the present invention,
Even if an air flow measuring device outputs an incorrect measurement signal corresponding to a noise signal, the measurement signal output corresponding to this noise signal can be effectively eliminated,
The purpose is to ensure that engine control is executed stably and with high precision.

[Means for Solving the Problems] That is, the engine control device according to the present invention heats the temperature sensing element set in the intake pipe by the energization start signal generated at a specified period. A current is set to be supplied, and the supply time width of this heating current is set in accordance with the temperature rise state of the temperature sensing element, so that the measured value of the air flow rate is expressed as a measurement signal by the time width of the heating current. to be done.

In this case, if a noise signal is mixed into the energization start signal, heating and
The current is set, assuming a delay time width from the rise of the energization start signal to the rise of the pulse-like measurement signal, and then set the current to rise at a time other than the above delay time width from among the measurement output signals. The output signal is excluded, and only the output signal generated in response to the energization start signal is read into the engine control unit as the air flow measurement signal.

[Operation] In the engine control device configured as described above, the amount of intake air supplied to the engine is expressed as a time width signal that can be digitally processed. and can be effectively used in microcomputers. In addition, even if a noise signal is mixed in during this air flow measurement, the signal component generated in response to this noise signal is removed from the measurement output signal, and the microcomputer returns a normal measurement signal. This means that stable engine control can be carried out effectively.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows its configuration, and a temperature sensing element 12 is set inside an intake pipe 11 that supplies intake air to an engine (not shown).

The temperature sensing element 12 is constituted by a resistance element, such as a platinum wire, which has a temperature characteristic whose resistance value is set to change depending on the temperature. An auxiliary temperature sensing element 13 having a similar configuration to the temperature sensing element 12 is set, and a resistance value corresponding to the temperature of the air flowing through the temperature sensing element 11 is set.

A fixed resistance 14 is connected in series to such a temperature sensing element 12, and a series circuit of fixed resistances 15 and 16 is connected to the auxiliary temperature sensing element 13. . This temperature sensing element 12 and auxiliary temperature sensing element 13
Each of the series circuits is one branch of the bridge circuit, and the connection point between the temperature sensing element 12 and the auxiliary temperature sensing element 13, which is the input end of this bridge circuit, is connected to the switching element and the auxiliary temperature sensing element 13. The heating power is set to be supplied through the transistor 17.

The output terminal portion of the bridge circuit, specifically the connection point between the temperature sensing element 12 and the resistor 14, and the connection point between the resistors 15 and 16, is supplied to a comparator 18 to calculate the voltage at both output terminal portions. I'm trying to compare. Then, when the temperature of the temperature sensing element 12 rises to a specified temperature state with respect to the air temperature measured by the auxiliary temperature sensing element 13,
The output signal from the comparator 18 is set to rise.

The output signal from the comparator 18 controls the reset of the flip-flop circuit 19. This flip-flop circuit 19 is connected to the engine ll1ljll unit 20.
Although the details are not shown, this energization start signal is supplied to the control unit 20, for example, in response to a signal synchronized with the rotation of the engine.

generated accordingly. A pulse signal having a set pulse time width corresponding to the setting and resetting operations of the flip-flop circuit 19 is coupled to the engine control unit 20 via the output circuit 21, and is coupled to the engine control unit 20 via the output circuit 21. When the flip-flop circuit 19 is in the set state, the transistor 17 is set to conductive state, and the temperature sensing element 12 is supplied to the base circuit of the temperature sensing element 12.
Heating power is set to be supplied to the bridge circuit including the

In this case, the voltage of the heating power taken out through the transistor 11 is supplied to a differential amplifier 23 together with a reference voltage signal generated by a reference voltage power supply 22, and the base of the transistor 11 is controlled by the differential amplifier 23. The control is performed so that the voltage of the heating power supplied to the bridge circuit is set as a reference.

FIG. 2 explains the basic operation of the air flow rate measuring device configured as described above, and the engine control unit 20 periodically sends the energization start signal as shown in FIG. generated. This signal sets and controls the flip-flop circuit 19 so that its output signal rises as shown in Fig. starts to rise in the state shown in Figure (B).

When the heating power is increased in this way, the temperature of the GI element 12 rises at a rate corresponding to the air flow rate as shown in Figure (C), until the temperature reaches a specified temperature state. When the voltage rises, an output signal from the comparator 18 is generated as shown in FIG. and,
The flip-flop circuit 19 is reset by the output signal from the comparator 18, the heating power is cut off, the temperature of the temperature sensing element 12 is lowered, and the temperature sensor 12 waits for the next heating cycle.

In an air flow measuring device that operates in this manner, if a noise component is mixed into the energization start signal, for example, as shown in FIG. 3(A), the energization start signals Tin1, Tin2, ..., when a noise signal n is mixed in, the flip-flop circuit 19 is set and controlled by this noise signal @n, the heating power for the temperature sensing element 12 is also increased, and the output corresponding to this noise signal n is A signal will also be generated. That is, the output quantity T o shown in FIG. 3(B) corresponds to the normal energization start signals Tin1, Tin2, . . .
utl, Tout2,... are generated,
A signal Tn is generated even in response to a noise component n. In this case, the output signal obtained from the output circuit 21 shown in FIG. From the signals shown in , the rising edge is delayed by time Td1, Td2, . . . , respectively. This delay time falls within a specified time Td that takes into account the ambient temperature, individual differences in the constituent circuit elements, etc., and the signal received by the engine control unit 20 within this delay time is determined to be a regular air flow rate measurement signal. be considered.

Next, the flow of signal processing in the engine control unit 20 to which signals from the output circuit 21 are supplied will be explained. FIG. 4 shows the state of the generation control of the energization start signal. First, when an interrupt is generated by the signal N corresponding to the rotation of the engine, the energization start signal Tin is output in step 101. Then, in response to the generation of the energization start signal 7in, the event counter C is cleared in step 102 to count and measure the elapsed time since the signal Tin was generated.

In this way, the energization start signal is generated, and the output circuit 21
When the measurement output signal starts to be generated, an interrupt occurs due to the generation of this output signal, and in step 201 shown in FIG. Set value T1
Compare with.

Here, the set value T1 is set corresponding to the delay time width Td, and is the lower limit value of the allowable rise range of the output signal generated based on the normal energization start signal Tin, Similarly, the upper limit value is set at Ta2.

That is, in step 201 above, rC>TmIJ
.

If it is determined, this indicates that the output signal 70Ut is generated later than the lower limit value, and the process proceeds to the next step 202 in response to such a determination result. In this step 202, it is determined that rC<Tm2J, and when the determination result of this step 202 is rYesJ, it is determined that the signal TOtlt captured at that time is a signal generated within the set time range. It is something that

In the next step 203, it is determined whether this signal TOtlt is the first signal after the event counter was cleared. If a noise signal occurs in a very short time range after the energization start signal is generated, an output corresponding to the noise signal is generated between T-1 and Tm2 above. An output signal from circuit 21 is now supplied to control unit 20 . However, if it is determined in step 203 that this is the first Tout after the energization start signal is generated, it is determined that this signal TOUT is indeed a regular air flow measurement signal, and therefore in the next step 204. The pulse time width of the captured signal "rout" is measured. Then, in step 205, the measured air flow rate signal TOI
The air flow rate is calculated in accordance with Jt, and the calculated air flow rate data is used, for example, to calculate fuel injection time width, ignition timing, and the like.

Furthermore, if the determination result in steps 201, 202, and 203 is rNOJ, the signal at that time is eliminated as corresponding to a noise signal.

Here, the delay time Td is several to several tens of microseconds, and the T1 and T12 are set corresponding to this time Td. In this case, the lower limit value T1 is the energization start signal T
It may be set to the state immediately after the signal Tin is generated, but if a noise signal is generated immediately before the energization start signal, the state in which TOut rises immediately after the signal Tin is generated may also be set. be. Therefore, this T1 needs to be set so that it is used to exclude the output signal corresponding to the noise signal generated immediately before the energization start signal from the input signal to the engine control unit 20.

-Although not specifically explained in the above embodiment, when a noise signal is generated, in a measurement signal generated by a regular energization start signal following this noise signal, the temperature sensing element 12 Since it is operated to generate heat, there is a possibility that the pulse width of the output pulse-like signal is smaller than that in a normal case. Therefore, when the generation of the output signal Tout due to a noise signal is detected,
Control is required to correct or even delete subsequent regular measurement signals.

[Effects of the Invention] As described above, according to the present invention, even if a noise component is mixed into the energization start signal that is the measurement command signal when measuring air flow rate, it is possible to deal with this noise signal. The output signal generated by the engine control unit is reliably rejected during the input operation to the engine control unit, and it is ensured that only normal air flow measurement signals are used for calculations such as fuel injection amount. Become.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram for explaining an engine control device according to an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining the measurement operation in the air flow rate measuring means of the control device, and FIG. A signal waveform diagram illustrating a state when a noise signal is present in the air flow rate measuring means, and FIGS. 4 and 5 are flowcharts each illustrating a state in which the air flow rate measurement signal is taken into the control unit. 12... Temperature sensing element, 13... Auxiliary temperature sensing element, 17.
... Transistor (heating power switching) 18... Comparator, 19... Flip-flop circuit, 20... Engine control unit. Applicant's agent, patent attorney Takehiko Suzue, as shown in Figure 1 Figure 2 Figure 3 Figure 4 Figure

Claims (1)

[Claims] an engine control unit that performs electronic control of the engine; a temperature sensing element having temperature resistance characteristics set in an intake pipe that supplies intake air to the engine; and a period specified by the engine control unit. means for generating an energization start signal at the energization start signal; means for controlling the rise of the heating power supplied to the temperature sensing element in response to the energization start signal generated from the means; Means for controlling and interrupting the heating power when the temperature of the air has risen to a specified temperature state, and generating a measurement output signal corresponding to the supply time width of the heating power to the temperature sensing element to control the engine. means for setting the supply to the unit; means for setting a delay time width necessary for a normal output signal to be generated from the rise of the energization start signal; and means for setting the rise of the measurement output signal to the set delay time. and means for determining whether or not the delay time is within the delay time range, and the determining means excludes the output signal generated outside the delay time range from the measured output signal supplied to the engine control unit. Characteristic engine control device.