JPS63184018A - Control apparatus of heat ray type suction air flowmeter - Google Patents

Abstract

PURPOSE:To perform highly accurate detection without deteriorating a hot wire, by applying a high voltage current according to the calculated value based on the detection of an operation state and burning off the adhesion substance to the hot wire. CONSTITUTION:An engine control apparatus 20 reads suction air amount Qa(i) by an air flow sensor 2 after initial setting and adds the suction air amount Qa(i-1) of the previous time held in RAM 22 thereto to store the same as new suction air amount Qa(i). It is detected whether this suction air amount Qa(i) reaches predetermined burn-off condition forming suction air amount Qsurn and, corresponding to this, said air amount Qa(i) is stored in the practice number Ca of the integrated burn-off times in RAM. When an engine 1 is stopped, a predetermined high voltage current is allowed to flow to the hot wire of the sensor 2 for the time corresponding to the number of times Ca in RAM 22 to certainly burn off an adhesion substance without allowing an excessive current to flow. The past number of times Ca are stored and, corresponding to the increase thereof, the air amount of a burn-off practice condition is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control device for a hot wire intake air flowmeter that measures the amount of intake air using a hot wire output provided in the intake passage of an engine. .

[Prior Art] In a conventional burn-off system in which a high-voltage current is passed through a hot wire immediately after the engine is stopped to burn off dust, etc. attached to the hot wire, when the operating state satisfies a predetermined condition, e.g. Burn-off was performed only when the engine stopped for a certain amount of time, ie, a fixed amount. An example of this is JP-A-59-201935.

[Problems to be Solved by the Invention] In these conventional examples, in order to completely remove dust, burn-off had to be performed for a longer time than necessary, impairing the durability of the hot wire.

On the other hand, there were also cases where the burn-off time was insufficient and sufficient incineration ability could not be demonstrated.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above-mentioned problems, and as a means for solving the problems, this embodiment has the configuration shown in FIG. Equipped with

That is, an operating state detecting means for detecting the operating state, a calculating means for calculating the amount of applied electric power to be applied to the hot wire according to the detected state of the operating state detecting means, and a high voltage current applied to the hot wire according to the value calculated by the calculating means. and a burn-off means for applying a voltage and burning off deposits on the hot wire.

[Function] With the above configuration, dust can be removed from the hot wire under optimal conditions, and the amount of intake air can be detected with high accuracy without causing deterioration of the hot wire.

[Example] Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

[First Embodiment] FIG. 2 is a block diagram of an embodiment according to the present invention.
is the engine, 2 is the hot wire airflow meter,
3 is an injector, 4 is a fuel tank, 5 is a fuel pump, 6 is an ignition coil, 7 is a power distributor, 8 is a spark plug, 9 is an air-fuel ratio sensor,
10 is a catalyst, 11 is a silencer, 12 is a fuel sensor, 13 is a water temperature sensor, and 20 is an engine control device. The engine control device 20 includes a ROM that stores various initial values as well as control procedures shown in FIG. 3, which will be described later.
21 and a RAM 22 that temporarily holds processing progress data, etc.
is included.

The engine control of this embodiment having the above configuration will be explained below with reference to the flowchart of FIG.

First, in step S1, the engine control device initializes each data in the RAM 22 as initial processing only at the beginning. That is, the cumulative number i of the intake air amount Qa, the number CI of burn-off executions! Each j that holds the number of times information of l is set to “1”.
", and the previous intake air amount Qa (0) and the previous number of burn-off executions Ca (0) are initialized to "0". Then, the process proceeds to step S2, and the air flow meter 2 using a hot wire is used to The air amount Qa(i) is read out.In the subsequent step S3, the read intake air amount Qa(i
) and the previously read intake air amount Qa(i-1) stored in the RAM 22 to determine the new intake air amount Q.
It is stored in the RAM 22 as a(i).

Then, in step S3, it is determined whether the intake air amount Q a (i) accumulated in step S2 has reached a predetermined intake air amount, that is, whether (ct a(i)/Q aurn) > K. However, Qaurn is the amount of air that satisfies the burn-off condition, and K is a constant.

According to the inventor's research, this is, for example, W at 2000'rpm.
This is because it has been found that burn-off becomes necessary after approximately 4 hours of continuous operation under the operating conditions of , O, and T. More dirt adheres to the hot wire. Therefore, if this becomes too small for the cumulative air volume (■戟1さ"y<,Kiyoshiqq鈷S 1,011 raook), it becomes necessary to perform burn-off.

Note that when calculating the memory capacity required to store the cumulative air amount Qa(i) at this time, the air amount at idle is 1.
Approximately 2.5 g/sec is detected every m5 ec, so the minimum value of the air amount is 0.0025 g. Therefore, if LSB is 0.001g, then at 600 kg (6
0X 10') 10.001g, 60xl
O'<232 (=4 bytes), and the RAM 22 only needs to have a memory capacity of 4 bytes.

In this way, when there is a cumulative amount of intake air that requires burn-off, the process proceeds from step S4 to step S5, and f (
(Qa(i), / Qaurn), Ca(j-1))
is calculated and stored in the cumulative number of burn-off executions Cn(j) in the RAM 22. Here, the amount of burn-off is integrated as a number of times, but when performing burn-off, the burn-off time for each time is determined, and even if burn-off is performed repeatedly for the number of times, the current applied to the hot wire during burn-off will not be affected. It may be applied continuously for a number of times. Here, the cumulative number of burn-off executions up to the previous run C
Cumulative number of burn-off executions C until a(j-1) times of running standby
The reason why a (j-1) is included as a condition in the calculation formula is
This is because deterioration due to burn-off was taken into account.

Then, the process advances to step S6, and the cumulative air amount Qa(i) accumulated in step S3 this time is stored in the RAM in preparation for the next measurement.
In order to make the previous cumulative air amount Qa (i-1) in 22, (i
In step S8 of the 0th order (=i+1), it is checked whether the engine is stopped or not. If the engine is not stopped, the process returns to step S2 and the next intake air amount integration process is executed. Note that this integration of the amount of intake air need not be performed constantly, but may be performed at predetermined intervals.

Note that in step S4, (Q a(t)/Q Burn
)>K, there is no need to burn off yet, and the process returns to step S6.

In this way, the amount of burn-off is accumulated in preparation for burn-off.

When the engine stops here, the process moves from step S7 to step S8, where a predetermined high-voltage current is passed through the hot wire of the air flow sensor 2 for a time corresponding to the burn-off number C B (J) stored in the RAM 22 Note. To incinerate a kimono surely and without passing an extra current. When the burn-off at the optimum value is completed in this way, the process advances from step S8 to step S9, where the cumulative number of burn-off executions Ca(J-1) up to the previous run is added to the current cumulative number of burn-off executions Ca(j). Then, it is stored in the RAM 22 as a new cumulative number of burn-off executions CB(j).

Then, in step SIO, the newly stored cumulative number of burnoff executions Ca(l) is calculated as the previous cumulative number of burnoff executions CB('j-1
), and then perform the calculation of j=j+1 so that
11, the read intake air amount Qa (i-
1) to "O" to prepare for the next engine start.

As explained above, according to this embodiment, the intake air amount Qa during engine operation is integrated, and the number of burn-offs or the burn-off time is changed depending on the degree of the integrated value ΣQa, and the optimum value is selected. Appropriate burn-off can be performed on dirty wires.

Also, remember the number of burn-offs performed in the past,
As the number of burn-offs increases, the amount of air required to perform burn-off is reduced, thereby preventing accumulation of dirt and appropriately responding to a decrease in the incineration capacity of the hot wire.

[Second Embodiment] Note that the present invention is not limited to the above-described embodiments, and the hot wire contamination is determined based on the F/B correction amount during air-fuel ratio F/B control, and the degree of contamination (the size of the correction amount) is determined. By determining the number of burn-offs and the burn-off time, it is possible to perform an appropriate burn-off in response to contamination of the hot wire.

That is, in an engine control system that performs air-fuel ratio F/B control based on the detection signal No. 9 of the air-fuel ratio sensor 9 disposed in the exhaust pipe of the engine under a predetermined operating condition, for example, during idling, the F/B Contamination of the hot wire may be determined based on the B correction amount.

The functional block diagram when configured in this way is shown in Figure 4.
The control flowchart is shown in FIG.

As shown in the figure, the basic injection amount calculation means 201 reads the intake air amount Qa and the engine rotation speed N from the airflow sensor 2 (step 552), and based on these values, the basic injection amount T
p is calculated (step 553), and this is corrected by a predetermined correction amount based on the air-fuel ratio sensor 9 using the corrected injection amount calculating means 202 to calculate the corrected injection amount Ti (step 562).
, the injection valve driving means 203 controls the amount of fuel injection from the injector 3 based on this calculated value Ti (step 5).
63).

On the other hand, the comparison means 204 always compares whether or not the F/B condition is satisfied, and when the F/B condition is satisfied (for example, when the condition in step S54 is satisfied, for example, the cooling water temperature is 60° C. or higher). reads the air-fuel ratio V from the air-fuel ratio sensor 9 (step 555), and compares whether it is rich or not (step 5).
56).

Here, if it is 8, the positive amount calculation means 205 calculates the correction amount C0 corresponding to the result, step S57. Step 558), the corrected injection amount calculating means 202 calculates the corrected injection amount Ti considering the correction amount according to this result (
Step 562).

However, the burn-off condition determining means 206 constantly monitors and determines whether or not the burn-off amount calculation conditions are met based on the intake air amount Qa from the air flow sensor 2 and the engine rotation speed N. When the conditions are satisfied, for example in the case of idling operation, the burn-off number (time) calculating means 207 calculates the correction amount CIO (step 560), and also calculates the burn-off amount CB (step 561). Then, the burn-off execution means 208 executes the burn-off according to the integrated value of the burn-off amount Ca calculated by the burn-off number (time) calculation means 207 when performing burn-off such as stopping the engine (step 565).

With the configuration and control described above, the same effects as in the first embodiment can be obtained.

[Third Embodiment] Furthermore, in the case of a car using a gasoline engine, the control described above is changed to monitor the amount of gasoline in the fuel tank 4 with the fuel sensor 12, and to detect when the amount of gasoline consumed reaches a predetermined amount. Detect and.

The burn-off amount may be calculated from this value. This is because the dirt on the hot wire is approximately proportional to the intake air amount (passing air amount) of the engine, and also approximately proportional to the gasoline consumption amount.

In other words, in a gasoline engine, the amount of intake air is approximately 1
Since it is a constant value of 3 to 15 gr/sec, the amount of gasoline consumed is proportional to the amount of air passing through the hot wire,
This is because it is considered to be proportional to the degree of contamination of the hot wire.

The functional block diagram when configured in this way is shown in Figure 6.
The control flowchart is shown in FIG.

Here, each of the configurations 301 to 305 for controlling the injection valve drive is approximately the same configuration as in the second embodiment. The flow rate detection circuit 301 constantly monitors the detection output from the air flow sensor 2. ．． Karasu 1's palm belt (grim belt) Qa is detected and output to the basic injection amount calculation circuit 302. Basic injection amount calculation circuit 302
reads the intake air amount Qa from the flow rate detection circuit 301 and the engine rotation speed N via the power distributor 7, calculates the basic injection amount "rp" from these two values, and outputs this to the corrected injection amount calculation circuit 303. On the other hand, the correction amount calculation circuit 305
is the engine water temperature from the water temperature sensor 13 and 0 (not shown).
A correction injection amount calculation circuit that calculates a correction amount of fuel injection amount from the detected 02 value from two sensors.

303. For this reason, the correction injection amount calculation circuit 30
3 is the basic injection amount “r” from the basic injection amount calculation circuit 302.
p is corrected based on the fuel injection amount correction amount from the correction amount calculation circuit 305 to calculate the corrected injection amount Ti, and the injection valve drive circuit 304 controls the fuel injection from the injector 3 based on this calculated value Ti. Control quantity.

On the other hand, the burn-off control means 306 to 310 of this embodiment perform integration and control of the burn-off amount separately from these controls. The details of this control will be explained below with reference to FIG.

After the engine is started and the power is turned on, the gasoline consumption calculation circuit 306 reads the fuel level from the fuel sensor 12 and outputs it to the burn-off condition inversion circuit 307 as the gasoline consumption. The burn-off condition inversion circuit 307 monitors the state of the engine key in step S70, and monitors whether the engine has been started.

If the engine is started, the process advances to step S71, where the fuel level at the time of engine startup is read from the gasoline consumption calculation circuit 306, and the fuel level in the built-in non-volatile memory is read.
Mini rear store. Then, in step S72, the difference ΔF from the storage amount in the FE area in the non-volatile memory that stores the amount of gasoline in the fuel tank 4 when the engine was previously stopped.
In step S73, it is checked whether the amount of gasoline is increasing with ΔF≦Fs. If it has increased, it means that gasoline was refueled while the engine was stopped, and in step S73 the increased amount is added to the gasoline level FM at the time of the previous burn-off stored in the non-volatile memory, and in step S75. move on. If there is no increase, there is no refueling during the stop, and the process directly advances to step s75. Then, the process waits for the engine key to be turned off, and when the engine key is turned off, the process advances to step S76 and waits for the engine stop determination circuit 30B to determine that the engine has completely stopped. When the engine is stopped, the process proceeds from step S76 to step S77, and the burn-off condition determination circuit 307 reads the gasoline level FM from the gasoline consumption calculation circuit 306 again. Next step 3
At step 78, the calculation [FM]-[FE] is performed to obtain the gasoline consumption amount ΔF.

Then, in step S79, it is checked whether the gasoline consumption amount ΔF exceeds the threshold value F8 necessary for executing burn-off,
If it does not exceed the limit, burn-off is not necessary and step S8
In step 3, the previously read FM value is stored in the FM area of the memory. Then, in step S84, the power is turned off and the process ends.

On the other hand, if the burn-off conditions are satisfied in step S79, the process advances to step S80, and the burn-off execution circuit 309
calculates the number of times (or time) N in which burn-off should be performed by multiplying the gasoline consumption amount ΔF by a predetermined coefficient K. Then, one burn-off time n is set in the timer 310,
Burnoff is performed N times every n seconds (or once for N seconds). Then, in step 582, the value of F is stored in the FM area, and the process advances to step S83.

Here, FM, Fell (gasoline) amount level at previous burn-off + refueling amount FE; Fell level Fs at engine stop; Refueling judgment value K; Constant.

FB: Burn-off execution Fell consumption amount.

As explained above, during hot wire burn-off, it is possible to eliminate dust from the hot wire under optimal conditions, and the amount of intake air can be detected with high accuracy without causing deterioration of the hot wire.

In addition, the present invention can also be applied to the following examples.

■During continuous operation for long periods of time, there is no chance of burn-off, so the characteristics of the hot wire deteriorate. For this reason,
If the amount of gasoline consumed is also determined while the vehicle is running, it is possible to predict the dirtiness of the hot wire, and it is also possible to correct deviations in characteristics of the hot wire based on this amount of consumption.

■When refueling with gasoline, etc. without stopping the engine, the consumption amount may become a negative value. In this case, burn-off may be performed unconditionally.

■Fuel level becomes inaccurate when the car is tilted. Therefore, more accurate burn-off control can be achieved by providing a tilt sensor and correcting the fuel level based on the detected tilt.

[Effects of the Invention] As explained above, according to the present invention, deposits on the hot wire can be removed under optimal conditions, and the amount of intake air can be detected with high accuracy without causing unnecessary deterioration of the hot wire. It is possible to provide a control device for a hot wire type intake air flowmeter that can be used.

4. Brief explanation of the drawings FIG. 1 is a functional block diagram of an embodiment according to the present invention, FIG. 2 is a configuration diagram of an embodiment according to the present invention, FIG. 3 is a burn-off control flowchart of this embodiment, 5 is a burn-off control flowchart of another embodiment, FIG. 6 is a functional block diagram of still another embodiment of the present invention, and FIG. 7 is a functional block diagram of another embodiment of the present invention. It is a burn-off control flowchart of yet another example.

In the diagram, 1...engine, 2...air flow meter, 3...
...Injector, 4...Fuel tank, 5...
・Fuel pump, 6...Ignition coil,
7... Power distributor, 8... Spark plug, 9... Air-fuel ratio sensor, 10... Catalyst, 11... Silencer, 12
...Fuel meter, 13...Water temperature sensor, 20
...Engine control device, 21...ROM, 22...
- It is RAM.

Claims (3)

[Claims] (1) In a control device for a hot wire intake air flowmeter that measures the amount of intake air using a hot wire output arranged in the intake passage of an engine, there is provided an operating state detection means for detecting an operating state; Calculation means for calculating the amount of applied power to be applied to the hot wire according to the detection state;
A control device for a hot-wire intake air flow meter, comprising burning means for applying a high voltage current to the hot wire in accordance with a value calculated by the calculating means and burning off deposits on the hot wire. (2) Claim 1, wherein the burning means burns off the deposits on the hot wire immediately after the engine is stopped.
A control device for a hot-wire intake air flow meter as described in . (3) A control device for a hot-wire type intake air flowmeter according to claim 1 or 2, wherein the calculation means calculates the amount of power applied that is proportional to the cumulative amount of intake air.