JPH0237528B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a hot wire flow sensor, and particularly to a sensor that uses a Wheatstone bridge to detect the flow velocity or flow rate of air, liquid, etc. Recently, comprehensive control of engines using microcomputers is being carried out for the purpose of improving engine control functions. On the other hand, the control functions required for the engine vary depending on the vehicle type and purpose, and therefore, in an engine control system using a microcomputer, the software that operates the engine control device is versatile depending on the vehicle type and purpose. That is, a device that allows various control functions to be modified, changed, and added is required from the viewpoint of cost or improved controllability. Conventionally, the amount of air taken into an internal combustion engine has been determined by indirectly detecting the intake manifold pressure or by directly detecting the air flow rate to determine the total amount during the intake stroke. The former method has the drawbacks of poor accuracy because it is an indirect method, is affected by engine differences and deterioration, and has poor responsiveness, while the latter method has high accuracy (reading value ±1%) and - Requires a flow rate sensor with a wide range (1:50), which has the disadvantage of high cost. It is desirable to use a so-called hot-wire flow rate sensor as the flow rate sensor because it enables cost reduction, and its nonlinear output characteristics equalizes relative errors and allows a wide dynamic range. FIG. 1 shows the overall configuration of an engine system equipped with this hot wire flow rate sensor. In the figure, intake air passes through an air cleaner 2, a throttle chamber 4, an intake pipe 6, and is supplied to a cylinder 8. The gas burned in the cylinder 8 passes through the exhaust pipe 10 from the cylinder 8 and is discharged into the atmosphere. The throttle chamber 4 is provided with an injector 12 for injecting fuel, and the fuel injected from the injector 12 is exposed in the air passage of the throttle chamber 4 and mixed with intake air. A mixture is formed, and this mixture is supplied to the combustion chamber of the cylinder 8 through the intake pipe 6 when the intake valve 20 is opened. A throttle valve 14 is located near the outlet of the injector 12.
16 are provided. The throttle valve 14 is configured to be in mechanical communication with the accelerator pedal and is driven by the driver. On the other hand, the throttle valve 16 is arranged so as to be driven by the diaphragm 18, and is fully closed when the air flow rate is small.As the air flow rate increases, the negative pressure on the diaphragm 18 increases, so that the throttle valve 16 It begins to open and suppresses the increase in inhalation resistance. An air passage 22 is provided upstream of the throttle valves 14 and 16 of the throttle chamber 4.
2 is detachably provided with a hot wire flow meter 24, which will be described later, and extracts an electrical signal that changes in accordance with the air flow rate determined from the relationship between the air flow rate and the amount of heat transferred from the heating element. Since the hot-wire flowmeter 24 is installed in the air passage 22, it is protected from high-temperature gas generated when the cylinder 8 backfires, and is also protected from being contaminated by dust in the intake air. . The outlet of this air passage 22 is opened near the narrowest part of the bench lily, and the inlet thereof is opened on the upstream side of the bench lily. Although not shown in FIG. 3, the throttle valves 14 and 16 are provided with throttle angle sensors that detect the opening degrees of the throttle valves 14 and 16.
A detection signal from this throttle angle sensor is taken in from a throttle angle sensor 116 shown in FIG. 6, which will be described later, and is input to a multiplexer 120 of the first analog-to-digital converter. Fuel supplied to the injector 12 is supplied from a fuel tank 30 to a fuel pressure regulator 38 via a fuel pump 32, a fuel damper 34, and a filter 36. On the other hand, pressurized fuel is supplied from the fuel pressure regulator 38 to the injector 12 via a pipe 40.
From the fuel pressure regulator 38 to the fuel tank 3 so that the difference between the pressure in the intake pipe 6 where fuel is injected from the fuel tank 3 and the fuel pressure to the injector 12 is always constant.
Fuel is returned to zero via a return pipe 42. The air-fuel mixture taken in from the intake valve 20 is transferred to the piston 5
0 and is combusted by the spark from the ignition plug 52, and this combustion is converted into kinetic energy. The cylinder 8 is cooled by cooling water 54,
The temperature of this cooling water is measured by a water temperature sensor 56, and this measured value is used as the engine temperature. A high voltage is supplied to the ignition plug 52 from an ignition coil 58 in accordance with the ignition timing. Further, the crankshaft (not shown) is provided with a crank angle sensor that outputs a reference angle signal and a position signal at every reference crank angle and every fixed angle (for example, 0.5 angle) according to the rotation of the engine. The output of this crank angle sensor, water temperature sensor 56
The output 56A and the electrical signal from the heating element 24 are input to a control circuit 64 consisting of a microcomputer, etc., and are processed by the control circuit 64, and the injector 12 and the ignition coil 58 are driven by the output of this control circuit 64. Ru. In the engine system controlled based on the above configuration, the throttle chamber 4 is provided with a bypass 26 that straddles the throttle valve 16 and communicates with the intake pipe 6, and this bypass 26 has a bypass valve that is controlled to open and close. 62 are provided. A control input from the control circuit 64 is supplied to the driving section of the bypass valve 62, so that opening and closing of the bypass valve 62 is controlled. This bypass valve 62 faces the bypass 26 provided by bypassing the throttle valve 16, and is controlled to open and close by pulsed current. This bypass valve 62 changes the cross-sectional area of the bypass 26 by the lift amount of the valve, and this lift amount is controlled by driving a drive system by the output of the control circuit 64. That is, in the control circuit 64, an opening/closing cycle signal is generated to control the drive system, and the drive system uses this opening/closing cycle signal to send a control signal to the bypass valve 62 for adjusting the lift amount of the bypass valve 62.
This is applied to the second drive unit. As shown in FIG. 2, the hot wire flowmeter 24 has a cylindrical air guide member 2201 with a hot wire resistor 2204 and a hot wire resistor 2205 inside the cylinder, as shown in FIG. They are arranged parallel to each other. The upper row is the hot wire resistor 2204
The lower part is the temperature compensation resistor 2205. This air guiding member 2201 is for rectifying the turbulent flow of air that has entered the bypass passage 22, and inside the cylinder, the air inlet is curved to form a bench lily so that the air flow is rectified. ing. This air guide member 2201 is not required when the hot wire flowmeter is installed in the bypass passage.
This is especially necessary when it is installed within the throttle chamber 4. Further, the hot wire resistor 2204 and the temperature compensating resistor 2205 are wire-wound resistors in which the resistor is wound around a bobbin 2206, which is an insulating support, as shown in FIG. Further, the air guide member 2201 is connected to the support member 22
02, the support member 2202 is supported by the mounting flange 220 of the driver module 2203.
It is fixed at 7. Although the support member 2202 is formed in a cylindrical shape in FIG. 2, it does not necessarily have to be cylindrical. Inside this support member 2202 is a hot wire resistor 2204 and a temperature compensation resistor 2205.
A lead wire 2207 is provided to be connected to. An electronic circuit is connected to this lead wire 2207, and the electronic circuit is connected to the driver module 2203.
It's decorated. driver module 220
3 has a mounting flange 2208 to which a support member 2202 is fixed, and a housing 2209 that protects the electronic circuit. This housing 220
A connector 2210 for connecting to an external control device is provided on the side surface of 9. The amount of engine intake air measured by such a hot wire flow meter is not constant, but has small pulsations as shown in Figure 4, and the output signal from the flow sensor is nonlinear with respect to the intake air flow. have a relationship,
It is necessary to calculate the amount of air in the intake stroke from the responsive output signal in the form of integrating the air flow rate, and this integration requires complex arithmetic processing. That is,
The hot wire output voltage v is given by the mass flow rate q _A. Then, formula (1) further becomes v ² = C ₁ + C ₂ √ _A ……(2). Now, if the hot wire output voltage v is v=v ₀ when the rotational speed N=0 and the mass flow rate q _A =0, equation (2) becomes v ² ₀ =C ₁ . . . (3). Therefore, from equations (2) and (3), v ² = v ² ₀ + C ₂ √ _A ……(4) q _A = 1/C ₂ ² (v ₂ −v ² ₀ ) ² ……( 5) and the instantaneous mass flow rate q _A can be obtained from equation (5). Therefore, the average amount of air during one intake stroke
Q _A becomes as follows. Also, the fuel injection amount Q _F per intake stroke is
If N is the rotational speed and K is a constant, then Q _F = KQ _A /N... (7) Therefore, by finding Q _A , the fuel injection amount Q _A per rotation is determined by the rotational speed. This is the reason. Therefore, in order to capture this average air amount Q _A with a microcomputer, the intake air amount is pulsating as mentioned above, and the intake air amount must be sampled from the value of the hot wire output voltage corresponding to the intake air amount. In order to calculate the above
Calculations such as equation (5) must be performed, and the microcomputer is required to perform not only fuel injection control (hereinafter referred to as EGI), but also point nine advance angle control (hereinafter referred to as IGN), and idle speed control (hereinafter referred to as IGN). This is possible when the rotational speed is several _tens of revolutions, but it is possible if the rotational speed is several tens of revolutions. As the level increases, all you can do is calculate the amount of intake air. Therefore, the engine speed is divided into three modes, and the input of the output signal of the hot wire drive circuit of the engine speed in each mode to the microcomputer is synchronized with the crank rotation angle determined by each mode. It has been considered to prevent other controls of the microcomputer from becoming impossible due to fluctuations in the rotational speed and to perform fuel injection control reliably by taking in the time corresponding to the crank rotation angle.
However, when the load is low, hot wire flow sensors can measure the true amount of air, even taking into account the responsiveness of the hot wire, but as the load increases, the pulsation of the engine increases, making it difficult to measure the true air flow rate. It becomes impossible to measure the amount of air in the air. This is because the pulsation of the intake air due to the opening of the throttle valve as well as the opening of the intake and exhaust valves of the engine affects the mounting position of the flow rate sensor. Whether this pulsation occurs or not depends on the load, that is, the pressure inside the intake pipe. The pressure inside the intake pipe that causes pulsations that make it impossible to measure the true intake air amount with this flow rate sensor is (-)100
mHg. This intake pipe pressure and intake air amount Q _A
FIG. 5 shows the relationship between the intake pipe internal pressure and the throttle opening. That is, the horizontal axis shows the intake pipe internal pressure (load), and the vertical axis shows the intake air amount Q _A and the throttle opening. In the figure, the engine speed is now 100r.
A shows the relationship between the intake pipe internal pressure and the intake air amount Q _A when expressed as pm. The relationship between this intake pipe internal pressure and the intake air flow rate Q _A has linearity.
Similarly, B shows the relationship between the intake pipe pressure and the intake air flow rate Q _A when the engine speed is 5000 rpm. This 5000 rpm line B also has linearity. Curve C shows the relationship between the throttle opening and intake pipe pressure when the engine speed is 1000r.pm, and when the engine speed is 5000r.p.m.
Curve D shows the relationship between the throttle opening and the intake pipe pressure at m. Intake air flow rate in the diagram
When Q _A is almost 0, the pressure inside the intake pipe is (-)
500 mHg, and at this time the throttle opening is "0", that is, the throttle is in an idling state. Lines A and B, which show the characteristics of this hot wire flow sensor, are cut off at a pressure in the intake pipe of (-) 100 mHg because the pulsation is large at pressures above (-) 100 mHg, and the true intake air flow rate Q This is because _A cannot be measured. On the other hand, the throttle opening is
As shown by curves C and D, the characteristics of the throttle sensor are exhibited even after (-) 100 mHg, since it is completely unrelated to the pressure inside the intake pipe. Therefore, the true intake air flow rate Q _A cannot be measured with a hot wire flow rate sensor in a region where the pressure inside the intake pipe is (-) 100 mHg or more. The detected value from the sensor was corrected by software to determine the fuel amount as the intake air flow rate Q _A. Therefore, due to the pulsation, the engine may brake when the fuel amount is low when it should be accelerating, or the engine may accelerate when the fuel amount is increased even though it is decelerating (i.e., the accelerator is released). The drawback was that the engine speed could not be controlled sufficiently. Therefore, in order to determine the area where pulsation occurs in the airflow caused by the engine, we use the throttle opening and engine rotational speed, which are not affected by pulsations, to calculate the intake air flow rate, which is determined in advance from the relationship between the throttle opening and the intake pipe pressure, as the engine rotational speed. By controlling the fuel amount using the compensated intake air flow rate expressed in relation to the throttle opening, air pulsation is generated by the engine.
A method has been considered to perform optimal engine fuel control even in a region where the true intake air flow rate cannot be measured using a hot-wire type flow sensor. However, as mentioned above, conventional hot wire flowmeters have the disadvantage of not being able to obtain an appropriate air flow rate because they use a wire-wound resistor in which a resistor is wound around a bobbin that is an insulating support. There is. In other words, as is well known, the principle of a hot wire flowmeter is that when a resistor heated to a constant temperature by passing an electric current is placed in a fluid flow path, the amount of heat taken from the resistor changes depending on the flow rate of the liquid. In order to replenish the amount of heat taken away according to the change and maintain the resistor at a constant temperature, the current is controlled, and this current is converted into voltage and used as the fluid flow rate. In conventional hot wire flowmeters, when there is a sudden increase in flow rate, the temperature of the resistor drops rapidly and the current increases rapidly to maintain it at a constant temperature. Ceramics is used as the material for the insulating support, and as it has low thermal conductivity, the amount of heat transferred from the high temperature resistor is small, and it takes time for the temperature of the insulating support, which has dropped due to a sudden increase in flow rate, to reach equilibrium with the resistor. During this time, the above-mentioned current continues to increase and does not reach equilibrium, resulting in a problem that the response becomes extremely slow. An object of the present invention is to provide a hot wire flowmeter that is responsive to sudden changes in air volume (flow rate). The present invention provides linear resistance against sudden changes in air volume by winding a linear resistor in a coil around a rod-shaped or tubular support made of metal with high thermal conductivity and coated with an insulating film. It increases the amount of heat conduction from the body to the tubular support to quickly balance the temperature of the linear resistor and the tubular support, converges the current flowing through the linear resistor to an equilibrium value, and improves responsiveness. be. Examples of the present invention will be described below. FIG. 6 shows the entirety of a hot wire resistor 2220 of a hot wire flowmeter showing one embodiment of the present invention. In the figure, an insulating film 2222 is formed on the outer peripheral surface of a tubular metal support 2221. A linear resistor 2223 is wound in a coil shape on this insulating film 2222.
A protective film 2224 is applied on top of 223. Further, an electrode 2225 is provided at one end of the tubular metal support 2221. Hot wire resistor 2220 configured in this way
The metal support 2221 is a stainless steel tube with an outer diameter of 0.2φ, an inner diameter of 0.1φ, and a length of 5 mm, and a heat-resistant ceramic coating is provided as the insulating coating 2222 by coating and baking or plasma spraying. ing. Further, as the protective film 2224,
The glass material is coated and baked. Insulating film 222
The thickness of 2224 is 50 μm, and the thickness of protective film 2224 is
It is 15 μm. A characteristic diagram when this embodiment is used in a hot wire flowmeter is shown in FIG. That is, in the figure, A is a platinum wire with a wire diameter of 70 μφ and a length of 50 mm in the bare wire state.
The characteristics of a single linear hot wire resistor with a point-supported structure are shown, B is the present example, and C is an alumina pipe (outer diameter
A platinum iridium wire (0.2φ, length 2.5mm) is inserted as a lead wire into the inner diameter of the alumina pipe using platinum paste, and the platinum wire is wrapped around it using a bobbin fixed by baking. This figure shows the characteristics of a ceramic bobbin type hot wire resistor with a rolled glass film formed thereon. In the figure, A has a transient response time constant of 5 msec as a flow rate change, and C, which is a conventional bobbin type, has a time constant of 45 msec. In contrast, in this embodiment, the time is approximately 18 msec. Although A is the most excellent, it is actually impossible to use due to its backup fire, earthquake resistance, and mechanical strength. In addition, the conventional bobbin type C
In this case, the difference in time constant between heating and cooling becomes large, making it impossible to accurately grasp the pulsating flow. Further, the temperature distribution state of the relationship between the length and thickness of the bobbin of the hot wire resistor is shown in FIGS. 8a and 8b. FIG. 8a shows a case where the bobbin length is small and relatively thick, and the temperature distribution at this time is high at the center. On the other hand, FIG. 8b shows the case where the bobbin length is large and the thickness is small, and both FIGS. 8a and 8b show the case where the length of the linear resistors is the same, and the ratio of concentration in the center is low. Therefore, the larger the ratio l/d of thickness to length, the better. FIG. 9 is an explanatory diagram of the ignition device of FIG. 1,
A pulsed current is supplied to power transistor 72 via amplifier 68, and this current turns transistor 72 on. As a result, a primary coil current flows from the battery 66 to the ignition coil 68. The fall of this pulse current turns the transistor 74 into a cut-off state, and generates a high voltage in the secondary coil of the ignition coil 58. This high voltage is distributed via the power distributor 70 to each of the spark plugs 52 in each cylinder of the engine in synchronization with the engine rotation. Figure 10 shows exhaust gas recirculation (hereinafter referred to as EGR)
To illustrate the system, a constant negative pressure from a negative pressure source 80 is applied to a control valve 86 via a pressure control valve 84. The pressure control valve 84 is applied to the transistor 90 and controls the ratio of the constant negative pressure of the negative pressure source to the atmosphere 88 according to the ON duty ratio of the repetitive pulse, and controls the state of application of the negative pressure to the control valve 86. Therefore, the negative pressure applied to the control valve 86 is determined by the ON duty ratio of the transistor 90. The controlled negative pressure of the constant pressure valve 84 controls the amount of EGR flowing from the exhaust valve 10 to the intake pipe 6. FIG. 11 is an overall configuration diagram of the control system.
CPU 102 and read-only memory 104
(hereinafter referred to as ROM), random access memory 106 (hereinafter referred to as RAM), and input/output circuit 1
It consists of 08. The above CPU 102 is
Using various programs stored in the ROM 104, input data from the input/output circuit 108 is operated, and the operation results are returned to the input/output circuit 108 again. The intermediate storage required for these operations is RAM.
106 is used. CPU102, ROM104,
Various types of data are exchanged between the RAM 106 and the input/output circuit 108 via a bus line 110 consisting of a data bus, a control bus, and an address bus. The input/output circuit 108 includes a first analog-to-digital converter (hereinafter referred to as ADC1) and a second analog-to-digital converter (hereinafter referred to as ADC1).
analog to digital converter (hereinafter referred to as
ADC2) and angle signal processing circuits 126 and 1
It has an input means with a discrete input/output circuit (hereinafter referred to as DIO) for inputting and outputting bit information. ADC1 has a battery voltage detection sensor 132
(hereinafter referred to as VBS) and cooling water temperature sensor 56 (hereinafter referred to as VBS)
(hereinafter referred to as TWS) and atmospheric temperature sensor 122 (hereinafter referred to as TAS)
), the adjustment voltage generator 114 (hereinafter referred to as VRS), and the throttle angle sensor 116 (hereinafter referred to as θTHS)
The outputs of the λ sensor 118 (hereinafter referred to as λS) are applied to a multiplexer 120 (hereinafter referred to as MPX), and the MPX 120 selects one of them and converts it into an analog-to-digital conversion circuit 122 (hereinafter referred to as λS). (hereinafter referred to as ADC). ADC1
The digital value that is the output of 22 is stored in register 124.
(hereinafter referred to as REG). In addition, the flow rate sensor 24 (hereinafter referred to as AFS)
The signal is input to the ADC 2, converted into a digital signal via an analog-to-digital conversion circuit 128 (hereinafter referred to as ADC), and set in a register 130 (hereinafter referred to as REG). The angle sensor 146 (hereinafter referred to as ANGS) outputs a signal indicating a reference crank angle, for example, 180 degrees crank angle (hereinafter referred to as REF), and a signal indicating a minute angle, for example, 1 degree crank angle (hereinafter referred to as POS). The signal is applied to the angle signal processing circuit 126, where the waveform is shaped. DIO has an idle switch 148 (hereinafter
IDIE-SW) and top gear switch 1
50 (hereinafter referred to as TOP-SW) and a starter switch 152 (hereinafter referred to as START-SW) are input. Next, the pulse output circuit and control target based on the calculation results of the CPU will be explained. The injector control circuit (denoted as INJC) is a circuit that converts the digital value of the calculation result into a pulse output. Therefore, a pulse with a pulse width corresponding to the fuel injection amount is
It is generated by INJC 134 and applied to injector 12 via AND gate 136. The ignition pulse generation circuit 138 (hereinafter referred to as IGNC) has a register (hereinafter referred to as ADV) for setting the ignition timing and a register (hereinafter referred to as DWL) for setting the primary current energization start time of the ignition coil.
These data are set by the CPU. A pulse is generated based on the set data and is applied via AND gate 140 to amplifier 68, detailed in FIG. The opening rate of the bypass valve 62 is determined by the control circuit (hereinafter referred to as
ISCC) 142 via an AND gate 144.
ISCC142 is a register that sets the pulse width.
Register to set ISCD and repeat pulse period
Has ISCP. The EGR amount control pulse generation circuit 180 (hereinafter referred to as EGRC) that controls the transistor 90 that controls the EGR control valve 86 shown in FIG. 4 has a register that sets a value representing the duty of the pulse.
It has EGRD and a register EGRP for setting a value representing the pulse repetition period. This EGRC
The output pulse of is applied to transistor 90 via AND gate 156. Further, the 1-bit input/output signal is controlled by the circuit DIO. The input signal is IDLE-SW signal,
There is a TOP-SW signal and a START-SW signal. Further, the output signal includes a pulse output signal for driving the fuel pump. This DIO is provided with a register DDR for determining whether a terminal is used as an input terminal or an output terminal, and a register DOUT for latching output data. The register 160 is a register (hereinafter referred to as a register) that holds instructions for commanding various states inside the input/output circuit 108.
For example, by setting an instruction in this register, the AND gate 136,
140, 144, and 156 are all turned on or turned off. MOD like this
By setting the instruction in register 160,
You can control the stop and start of INJC, IGNC, and ISCC output. FIG. 12 is a diagram showing the basic configuration of a program system for the control circuit shown in FIG. 11. In the figure, an initial processing program 202,
The interrupt processing program 206, macro processing program 228, and task dispatcher 208 are management programs for managing task groups.
The initial processing program 202 is a program for performing preprocessing for operating the microcomputer, for example, clearing the memory contents of the RAM 106 or
It performs processing to set initial values of registers of 08, and to take in input information such as cooling water temperature Tw, battery voltage, etc. for preprocessing necessary for engine control. Also,
The interrupt processing program 206 accepts various interrupts, analyzes the cause of the interrupt, and issues an activation request to the task dispatcher 208 to activate a necessary task among the task groups 210 to 226.
As described later, interrupt factors include AD that occurs after AD conversion of input information such as power supply voltage and cooling water temperature.
Conversion interrupt (ADC), initial interrupt (INTL) that occurs in synchronization with engine rotation, interval interrupt (INTV) that occurs at set fixed time intervals, for example every 10ms, and even engine stop status. Detects and generates an engine stall interrupt (ENST)
etc. Each task in the task groups 210 to 226 is assigned a task number representing a priority order, and each task belongs to one of task levels 0 to 2. That is, tasks 0 to 2 belong to task level 0, tasks 3 to 5 belong to task level 1, and tasks 6 to 8 belong to task level 2. The task dispatcher 208 receives activation requests for the various interrupts, and allocates CPU occupation time based on the priorities assigned to the various tasks corresponding to these activation requests. Here, task priority control by the task dispatcher 208 is based on the following method. (1) Abort a low-priority task and transfer execution rights to a high-priority task only between task levels. It is assumed here that level 0 has the highest priority. (2)
If there is a task currently being executed or suspended within the same task level, this task has the highest priority and no other tasks can operate until this task is completed. (3) If there are activation requests for multiple tasks within the same task level, the smaller the task number, the higher the priority. Task Day Patschiya 2
The processing contents of step 08 will be described later, but in the present invention, a soft timer is provided in the RAM for each task in order to perform the above-mentioned priority control, and a control block for managing tasks in each task level is set in the RAM. There is. Each time the execution of each task is completed, the macro processing program 228 reports the completion of the execution of the task to the task dispatcher 208. Next, the processing contents of the task dispatcher 208 will be explained based on FIGS. 13 to 19.
FIG. 13 shows a task control block provided in the RAM managed by the task dispatcher 208. The number of task control blocks equal to the number of task levels is provided, and in this embodiment, three task control blocks are provided at task levels 0 to 2. Eight bits are assigned to each control block, of which the 0th to 2nd bits (Q ₀ to Q ₂ ) are activation bits that display the activation request task, and the 7th bit (R) is the activation bit that indicates the activation request task. The execution bit indicates whether any task is currently being executed or suspended. The activation bits Q ₀ to Q ₂ are arranged in descending order of execution priority within each task level. For example, the activation bit corresponding to task 4 in FIG. 12 is arranged at task level 1.
Q is ₀ . If there is a request to start a task, a flag is set in one of the start bits, and the task dispatcher 208 searches for the issued start request in order from the start bits corresponding to higher-level tasks and selects the start bits. It resets the flag corresponding to the activated activation request, sets flag 1 in the execution bit, and performs processing to activate the corresponding task. FIG. 14 shows a start address table provided in RAM 106 managed by task dispatcher 208. Start address SA0 to SA
8 is the task group 210 to 226 shown in FIG.
The start addresses corresponding to each task 0 to 8 are shown. 16 bits are allocated to each start address information, and these start address information are used by the task dispatcher 208 to start the corresponding task for which a start request has been made, as will be described later. Next, FIGS. 15 and 16 show the processing flow of the task dispatcher. In FIG. 14, when task dispatcher processing is started in step 300, it is determined in step 302 whether or not execution of a task belonging to task level 1 is being suspended. That is, if the execution bit is set to 1, it means that the macro processing program 228 has not yet issued a task completion report to the task dispatcher 208.
Indicates a state in which a task that was currently being executed is interrupted due to an interrupt with a higher priority level. Therefore, if flag 1 is set in the execution bit, the process jumps to step 314 and resumes the suspended task. On the other hand, if flag 1 is not set in the execution bit, that is, if the execution display flag is reset, the process moves to step 304, and it is determined whether there is a task waiting to be activated at level l. That is, the activation bits of level l are searched in the order of the execution priority of the corresponding task, that is, in the order of Q ₀ , Q ₁ , and Q ₂ . If flag 1 is not set in the activation bit belonging to task level 1, the process moves to step 306, and the task level is updated. That is, the task level l is incremented by +1 to l+1. When the task level is updated in step 306, the process moves to step 308, where it is determined whether all task levels have been checked. If all levels have not been checked, i.e. l=2, step
Returning to 302, the process is performed in the same manner as above. If all task levels have been checked in step 308, the process moves to step 310, where the interrupt is canceled. That is, since interrupts are prohibited during the processing period from step 302 to step 308, the interrupt is canceled at this step. Then, in the next step 312, the next interrupt is generated. Next, in step 304, if there is a task waiting to be activated at task level 1, that is, if the flag 1 is set in the activation bit belonging to task level 1, the process moves to step 400. In the loop of steps 500 and 502, which activation bit of task level l is set as flag 1 is searched in the order of the corresponding high priority execution level, that is, in the order of Q ₀ , Q ₁ , and Q ₂ . Once the relevant activation bit has been determined, the process moves to step 404, where the flagged activation bit is reset and a flag 1 is set to the execution bit (hereinafter referred to as the R bit) of l of the relevant task level. Furthermore, in step 406, the starting task number is determined, and in step 408, the task number shown in FIG. 14 is determined.
The start address information of the corresponding startup task is retrieved from the start address table provided in the RAM. Next, in step 410, a determination is made as to whether or not to execute the corresponding startup task. Here, if the extracted start address information is a specific value, for example 0, it is determined that the corresponding task does not need to be executed. This determination step is necessary to selectively provide the function of only a specific task to each vehicle type among the group of tasks that perform engine control. If it is determined in step 410 that the execution of the relevant task has been stopped, the process moves to step 414, where the R bit of the relevant task level 1 is reset. Then, the process returns to step 302 and it is determined whether the task level l is suspended. Since there may be cases in which a plurality of activation bits are flagged during the same task level, the R bit is reset in step 414 and then the process proceeds to step 302. On the other hand, if the execution of the relevant task is not stopped in step 410, that is, if it is to be executed, the process moves to step 412, jumps to the relevant task, and executes the task. Next, FIG. 17 is a diagram showing the processing flow of the macro processing program 228. This program consists of steps 562 and 564 to find the finished task. In steps 562 and 564, the task level is searched starting from 0 to find the completed task level. As a result, the process advances to step 568, where the execution (RUN) flag in the 7th bit of the task control block of the completed task is reset. This means that the task has completed execution. Then, the process returns to the task dispatcher 208 again and the next task to be executed is determined. Next, the execution and interruption of tasks when task priority control is performed by the task dispatcher 208 will be explained with reference to FIG. Here, m in the activation request N _no represents the task level, and n represents the priority order within the task level m. Assuming that the CPU is currently executing the management program OS, if startup request N ₂₁ occurs while this management program OS is running, the task corresponding to startup request N ₂₁ , that is, task 6, will be executed at time T ₁ . Begins. Here, while task 6 is being executed, a request to start a task with a higher execution priority is made at time T ₂ .
If N ₀₁ occurs, execution moves to the management program OS, and after performing the predetermined processing described above, the time is
At _T3 , execution of the task corresponding to startup request _N01 , ie, task 0, is started. If a startup request N ₁₁ is received at time T ₄ during the execution of task 0, execution will once again be transferred to the management program OS and predetermined processing will be performed, and then task 0, which was suspended at time T ₅ , will be executed again. execution is resumed. When the execution of task 0 ends at time T ₀ , the execution is transferred again to the management program OS, where the macro processing program 228 reports the completion of execution of task 0 to the task dispatcher 208, and at time T ₇ it waits for startup again. Execution of task 3 corresponding to activation request _N11 that was previously executed is started. Execution time T ₃ of this task 3
When a startup request _N12 of the same task level 1 with a lower priority is received, the execution of task 3 is temporarily interrupted and the execution is transferred to the management program OS, after which the predetermined processing is performed, and the task is restarted at time _T9 . 3 is resumed. When the execution of task 3 is completed at time T ₁₀ , the execution of the CPU is transferred to the management program OS, and the macro processing program 228 reports the completion of execution of task 3 to the task dispatcher 208, and then at time T ₁₁ , the execution of task 3 is transferred to a higher priority level. The execution of task 4 corresponding to the low startup request N ₁₂ is started, and when the execution of task 4 is completed at time T ₁₂ , the execution is transferred to the management program OS and the predetermined processing is performed, which has been suspended until now. Execution of task 6 corresponding to activation request N ₂₁ is resumed from time T ₁₃ . Priority control of tasks is performed in the manner described above. FIG. 13 shows state transitions in task priority control. The Idle state is a state where the task is waiting to be started, and no start request has been issued to the task yet. The next time a startup request is issued, a flag is set on the startup bit of the task control block, indicating that startup is necessary. The time it takes to move from the Idle state to the Queue state is determined by the level of each task. Furthermore
They are executed even in the Queue state, and the order is determined by priority. The task enters the execution state at the task dispatcher 20 in the management program OS.
This is after the activation bit flag of the task control block is reset in step 8 and the R bit (seventh bit) is set. This will start executing the task. This state is the RUN state. When the execution is completed, the R bit flag of the task control block is cleared, and the completion report is ended. This ends the RUN state and returns to the Idle state, waiting for the next startup request. However, if an interrupt IRQ occurs during execution of a task, that is, during RUN, the task must suspend execution. As a result, the contents of the CPU are saved and execution is interrupted.
This state is the Ready state. Next, when this task is ready to be executed again, the saved contents are returned to the CPU from the save area and execution is resumed. In other words, it returns from the Ready state to the RUN state again. In this way, each level program repeats the four states shown in FIG. Although FIG. 18 shows a typical flow, there is a possibility that the start bit of the task control block will be flagged in the Ready state. This is the case, for example, when the timing of the next activation request for the task comes while the activation is being suspended. At this time R
The bit flag is given priority and the suspended task is terminated first. As a result, the R bit flag disappears, and the startup bit flag causes the device to enter the Queue state without passing through the Idle state. In this way, tasks 0 to 8 are each in one of the states shown in FIG. Next, FIG. 20 shows a specific embodiment of the program system shown in FIG. 12. In the figure, the management program OS is the initial processing program 202,
It consists of an interrupt processing program 206, a task dispatcher 208, and a macro processing program 228. The interrupt processing program 206 includes various interrupt processing programs, and the initial interrupt processing (hereinafter referred to as INTL interrupt processing) 602 uses an initial interrupt signal that is generated in synchronization with engine rotation to interrupt half of the number of engine cylinders per engine rotation. That is, if it is a 4-cylinder engine, the initial interrupt will occur twice. By this initial interrupt, the fuel injection time calculated by the EGI task 612 is set in the EGI register of the input/output interface circuit 108. There are two types of AD conversion interrupt processing 6041
One is the AD converter 1 interrupt (hereinafter abbreviated as ADC1) and the AD converter 2 interrupt (hereinafter abbreviated as ADC2). The AD converter 1 has an accuracy of 8 bits and is used for inputting power supply voltage, cooling water temperature, intake air temperature, usage adjustment, etc., and starts conversion at the same time as specifying the input point to the multiplexer 120. Generates ADC1 interrupt after completion. Note that this interrupt is used only before cranking. or
The AD converter 128 is used to input the air flow rate and generates an ADC2 interrupt after the conversion is completed. Note that this interrupt is also used only before cranking. Next, the interval interrupt processing program (below
It is referred to as INTV interrupt processing program. ) 606, the INTV interrupt signal is generated at intervals of, for example, 10 ms, set in the INTV register, and is used as a basic signal for time monitoring of tasks to be started at regular intervals. This interrupt signal updates the soft timer and activates the mask that has reached the specified period. Furthermore, an engine stall interrupt processing program (hereinafter referred to as the ENST interrupt processing program) 608 detects the engine stop state, and when an INTL interrupt signal is detected, it starts counting and waits for the next INTL interrupt signal within a predetermined period of time, for example, one second. An ENST interrupt occurs when it cannot be detected. and
Even if ENST interrupt occurs 3 times, e.g. 3 seconds have elapsed
If the INTL interrupt signal cannot be detected, it is determined that an engine stall has occurred, and the ignition coil is energized and the fuel pump is stopped. After these processes, the process waits until the starter switch 152 is turned on.
Table 1 shows an overview of the processing for the above interrupt factors.

【table】

[Table] The initial processing program 202 and macro processing program 228 perform the processing as described above. The task groups activated by the various interrupts mentioned above are as follows. Tasks belonging to task level 0 include an air amount processing task (hereinafter referred to as AS task), a fuel injection control task (hereinafter referred to as EGI task), and a start monitor task (hereinafter referred to as MONIT task). Tasks belonging to task level 1 include an AD1 input task (hereinafter referred to as ADIN1 task) and a time coefficient processing task (hereinafter referred to as AFSIA task). Furthermore, the tasks belonging to task level 2 are the idle rotation control task (hereinafter referred to as ISC task), the correction calculation task (hereinafter referred to as HOSEI task), and the start preprocessing task (hereinafter referred to as ISTRT).
There are tasks (written as tasks). Table 2 shows the assignment of each task level and the function of the task.

【table】

[Table] As is clear from Table 2, the activation cycle of each task activated by various interrupts is determined in advance, and this information is stored in the ROM 104. Next, INTL interrupt processing, which shows the signal processing method of the hot wire flow rate sensor, will be explained. The signal from the hot wire flow rate sensor is taken in by an INTL interrupt, and the take-in timing is divided into three modes depending on the engine speed and differs in each mode. That is, as shown in FIG. 15, in mode 0, the rotation speed N is N<1600 rpm,
In mode 1, the rotation speed N is 1600rpm≦N≦
3200rpm, mode 2, rotation speed N is 3200rpm<N
This is for a 4-cylinder engine. Therefore, a crank rotation angle of 180 degrees corresponds to one intake stroke. In this example, mode 0 is shown for N=1600 rpm, mode 1 is shown for N=3200 rpm, and mode 2 is shown for N=6400 rpm. Therefore, mode 1 rotates twice as much as mode 0 in the same amount of time, and mode 2 rotates four times as much as mode 0 and twice as much as mode 1. is shown in FIG. The signal processing method of this hot wire flow sensor is as follows:
Set to perform sampling. In other words, in mode 0, sampling is performed every time corresponding to a crank rotation angle of 18 degrees, and in mode 1
In this case, since the rotational speed N is doubled, the acquisition timing is every time corresponding to a crank rotation angle of 36 degrees, and in mode 2, the rotational speed N is four times as much as in mode 0. Therefore, sampling is performed at intervals corresponding to a crank rotation angle of 72°. Therefore, for each mode,
When converted to the crank rotation angle in one intake stroke, it is the same as data captured at the same crank rotation angle as the data captured in mode 0. By changing the data acquisition timing depending on the engine speed in this way, the data processing time is not affected by fluctuations in the engine speed. The INTL interrupt processing flow for signal acquisition of such a hot wire flow rate sensor is shown in FIG. In the figure, first, in step 801,
Determine whether INTL is an interrupt. In the case of an INTL interrupt, it is determined in step 802 whether the analog counter is 0 (zero). If the analog counter is 0 (zero), the A/D converter is activated in step 803 to start taking in the air amount v. v
When the intake of the air amount v starts, in step 804, a timer is set for the next intake of the air amount v based on the engine rotation speed and the engine rotation speed mode. When the timer time is set in step 804, EGIREG, IGNREG, etc. are set in step 805, and then in step 806, interrupt prohibition is canceled only for INTLIRQ, and the INTL interrupt processing program ends. In step 802, if the analog counter is not zero, the process moves to step 805. Further, if it is determined in step 801 that it is not an INTL interrupt, it is determined in step 807 whether or not it is a timer interrupt for Q _A. In the case of a timer interrupt, it is determined in step 808 whether or not a timer interrupt prohibition flag is set. Ends if the prohibition flag is set. Also, if the prohibition flag is not set, the step
At 809, take in v and set the analog counter to +1. Next, in step 810,
Whether or not the import of v has been completed (whether or not the number of imports indicated by the analog counter has completed the specified number of imports)
Determine. When the import of v is completed, step 811
At step 812, the timer is stopped and the analog counter is reset at step 812. Further, if it is determined in step 810 that the capture has not been completed, v is activated in step 813. Next, in step 814, v ² is calculated and stored in RAM. Further, if it is determined in step 807 that it is not a timer interrupt, it is determined in step 815 whether or not it is an ADC interrupt. ADC at step 815
If it is an interrupt, in step 816,
Determine whether IST=1 or not, and if IST=1,
In step 817, v is captured. This v is used to detect pushing. Also, if it is not an AD interrupt in step 815, step
If IST=1 in 816, both
The process moves to INTV interrupt processing 606 in FIG. Next, Fig. 20 shows air amount signal processing (AC) 6
The ten tasks will be explained. The air amount signal processing task is activated in step 901, as shown in FIG. When the task is launched,
In step 902, a capture prohibition flag for v is set. Next, in step 903, (v ² ) ² is calculated and stored in RAM. Next step 904
At this point, the capture prohibition flag is reset. After resetting the capture prohibition flag, in step 905, the values (V ² ) ² stored in the RAM are integrated and averaged. After integrating and averaging, in step 906, the intake air flow rate Q _A is calculated from the hot wire flow rate sensor. After calculating the intake air flow rate Q _A in step 906, the engine rotation speed is taken in step 907, and the throttle sensor opening degree is taken in step 908. When the engine speed and the throttle opening are input from the throttle sensor, in step 909 the load is calculated from the engine speed and the throttle opening. After performing this load calculation, it is determined in step 910 whether the operating engine condition is in the compensation region, and if it is determined to be in the compensation region, in step 911,
In step 909, compensation Q _A is calculated from the engine speed and throttle opening used for load calculation. This compensation Q _A is formed in the form of a map as shown in FIG. 24 and is stored in the ROM. In the map shown in FIG. 24, the horizontal axis represents the throttle opening, the vertical axis represents the engine speed, and the intersection between the throttle opening and the engine speed is the compensation Q _A. This control map has been determined in advance through experiments. In this way, the steps
If it is determined in step 910 that it is in the compensation region, compensation Q _A is used for fuel amount control in step 911, and the process moves to step 912. Further, if it is determined in step 910 that it is not in the compensation area, it is determined in step 912 whether or not the engine is in an accelerating state. If it is determined in step 912 that the fuel is in an accelerated state, accelerated injection is performed in step 913, and then the process moves to macro processing 228 in FIG. The INTV interrupt processing will be explained below based on FIGS. 25 to 28. Figure 20 shows RAM1
It is a soft timer table provided in 06,
This soft timer table is provided with as many timer blocks as the number of different activation cycles activated by various interrupts. Here, the timer block refers to a storage area to which time information regarding the activation cycle of tasks stored in the ROM 104 is transferred. It is stored at the left end in the same figure.
TMB means the starting address of the soft timer table in RAM 106. Each timer block in this soft timer table has a
From the ROM 104, time information regarding the activation cycle, that is, when an INTV interrupt is performed every 10 ms, for example, a value that is an integer multiple of the INTV interrupt is transferred and stored. Next, FIG. 26 shows the processing flow of INTV interrupt processing 606. In the same figure, when the program is started at step 626, RAM10 is started at step 628.
The soft timer table provided at 6 is initialized. That is, the content i of the index register is set to 0 and the remaining time _T1 stored in the timer block at address TMB+0 of the soft timer table is checked. Here in this case T ₁
= T ₀ . Next, in step 630, repeat the above steps.
It is determined whether the soft timer checked in 628 is stopped. That is, if the remaining time T ₁ stored in the soft timer table is T ₁ = 0, it is determined that the soft timer is stopped, and the corresponding task to be started by the soft timer is stopped. It is determined that this is the case, and the process jumps to step 640, where the soft timer table is updated. Meanwhile, the remaining time T ₁ in the soft timer table
If T ₁ ≠0, the process moves to step 632 and the remaining time of the timer block is updated.
That is, the remaining time _T1 is decremented by -1. Next, in step 634, it is determined whether the soft timer in the timer table has reached its activation period. That is, if the remaining time T ₁ is T ₁ =0, it is determined that the activation period has been reached, and in that case, the process moves to step 636. Also, if it is determined that the soft timer has not reached its activation cycle, the step
640, and the soft timer table is updated. If the soft timer table has reached its activation period, the remaining time _T1 of the soft timer table is initialized at step 636. That is,
The time information of the activation cycle of the relevant task is transferred from the ROM 104 to the RAM 106. and step
After initializing the remaining time _T1 of the soft timer table in step 636, the activation requirements for the task corresponding to the soft timer table are performed in step 638. Next, in step 640, the soft timer table is updated. In other words, the contents of the index register are increased by +1.
Increment. Further, in step 642, it is determined whether all soft timer tables have been checked. That is, as shown in FIG. 20, since only N+1 soft timer tables are provided in this embodiment, the content i of the index register is
= N+1, it is determined that all soft timer tables have been checked, and the process proceeds to step 644.
The INTV interrupt processing program 606 ends.
On the other hand, if it is determined in step 642 that all soft timer tables have not been checked, the process returns to step 630 and the same processing as described above is performed. As described above, a request to start the corresponding task is issued in response to various interrupts, and the corresponding task is executed based on the request, but it is possible that all of the task groups listed in Table 2 are always executed. Instead, time information regarding the activation cycle of the task group provided in the ROM 104 is selected based on the engine operating information, and is transferred and stored in the soft timer table of the RAM 106. If the activation cycle of a given task is, for example, 20ms, the task will be activated at each interval, but if the task needs to be activated continuously depending on the operating conditions, then the task will be activated at all times. The soft timer table corresponding to that task is updated and initialized. Next, the manner in which the task group is started and stopped by various interrupts according to engine operating conditions will be explained with reference to a time chart shown in FIG. 22. Starter switch 1
When the power is turned on by operating step 52,
The CPU operates and 1 is set in the software flag IST and software flag EM. The software flag IST is a flag that indicates that the engine is in a state before starting.
EM is a flag to disable ENST interrupts. These two flags are used to determine whether the engine is in a pre-starting state, in a starting state, or in a post-starting state. Now, when the power is turned on by operating the starter switch 152, the task ADIN1 is activated first, and input information such as cooling water temperature, battery voltage, etc. necessary for starting the engine is inputted via the multiplexer 120 to AD conversion by various sensors. The data is input into the device 122, and the task is
The HOSEI task correction is activated and correction calculations are performed based on the input information. Also, the task ADIN1
As a result, the task ISTRT is activated every time data from various sensors are input to the AD converter 122 once, and the fuel injection amount required during engine startup is calculated. The above three tasks, namely task ADIN1,
Tasks HOSEI and ISTRT are started by the initial processing program 202. When the starter switch 152 turns ON, the task ADIN1 and
Three tasks, task MONIT and task ADIN2, are activated. That is, these tasks need to be executed only while the starter switch 152 is in the ON state (during cranking of the engine). During this period, from ROM104
Time information of a predetermined activation cycle is transferred and stored in a soft timer table corresponding to each of the tasks provided in the RAM 106. During this period, the remaining time _T1 of the activation cycle in the soft timer table is initialized and the activation cycle is repeatedly set. Task MONIT is a task to calculate the fuel injection amount when starting the engine, and is unnecessary after the engine starts. Therefore, after the task has been executed a predetermined number of times, the soft timer will stop starting, and when the task ends, The issued stop signal activates a group of tasks other than those mentioned above that are required after the engine is started. To stop a task using a soft timer, a signal indicating that the task has ended is used to store 0 in the corresponding soft timer table of the task at the time when the task is determined to have ended. The task is stopped by clearing the contents. Therefore, since the configuration is such that tasks can be easily activated and stopped using a soft timer, it is possible to efficiently and reliably manage a plurality of tasks having different activation cycles. Next, the IRQ generation circuit is shown in FIG. A register 735, a counter 736, a comparator 737, and a flip-flop 738 are an INTV IRQ generation circuit, and the INTV IRQ generation period is set in the register 735, for example, 10 [ms] in this embodiment.
In response, a clock pulse is set to counter 736, and when the count value matches register 735, flip-flop 738 is set. In this set state, the counter 736 is cleared and counting is restarted. Therefore, INTV IRQ is generated at regular intervals (10 msec). Register 741, counter 742, and comparator 74
3. Flip-flop 744 is an ENST IRQ generation circuit that detects engine stoppage. The register 741, counter 742, and comparator 743 are the same as those described above, and the count value is
Generates ENST IRQ when the value of is reached. However, while the engine is rotating, the counter 742 is cleared by the REF pulse generated by the crank angle sensor at every fixed crank angle, so the count value of the counter 742 does not reach the value of the register 741.
ENST IRQ will not occur. INTV occurred on flip-flop 738
ENST generated on IRQ or flip-flop 744
IRQ and IRQ generated by ADC1 and ADC2 are flip-flops 740, 746, and 76, respectively.
It is set to 4,768. Furthermore, signals for generating or inhibiting IRQ are set in flip-flops 737, 745, 762, and 766. Flip-flop 737, 745, 762, 766
If “H” is set in the AND gate 74
8,750,770,772 becomes active and IRQ
When , an IRQ is generated immediately from the OR gate. Therefore, flip-flops 737, 745, 76
Depending on whether "H" or "L" is input to each of 2,766, generation of IRQ can be inhibited or inhibited. Furthermore, when an IRQ occurs, the contents of flip-flops 740, 746, 764, and 768 are loaded into the CPU, so that the cause of the IRQ can be determined. When the CPU starts executing a program according to the IRQ, the IRQ signal needs to be cleared, so the flip-flop 7 related to the IRQ that started execution
Clear one of 40,746,764,768. Therefore, according to this embodiment, the thermal inertia can be reduced, and since the bobbin material has high thermal conductivity, the temperature distribution on the surface of the resistor can be made uniform. Further, according to this embodiment, even if there is a fluctuation in the flow rate, it is possible to detect it with good response. According to the present invention, by using a metal with high thermal conductivity for the support of the linear resistor, the temperature of the linear resistor and the tubular support can be quickly balanced against sudden changes in the amount of air. As a result, the responsiveness of flow rate measurement is improved.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing the control device for the entire engine system, Fig. 2 is a perspective view of a conventional hot wire flowmeter,
Fig. 3 is a cross-sectional view of Fig. 2, Fig. 4 is an output characteristic diagram of the hot wire output voltage V with respect to the crankshaft rotation angle, Fig. 5 is the intake pipe internal pressure and intake air flow rate Q _A ,
Figure 6 is a cross-sectional configuration diagram of a hot wire resistor showing an embodiment of the present invention, Figure 7 is a comparative characteristic diagram between the embodiment shown in Figure 6 and a conventional example, Figure 8 a , b is a diagram showing the temperature distribution state with respect to the shape of the illustrated embodiment in FIG. 6, FIG. 9 is an explanatory diagram of the ignition device in FIG. 1, FIG. Figure 11 is an overall configuration diagram of an engine control system, Figure 12 is a diagram showing the basic configuration of a program system for an engine control method according to the present invention, and Figure 13 is a diagram showing a task control system provided in RAM managed by a task dispatcher. FIG. 14 is a diagram showing the start address table of task groups activated by various interrupts. FIGS. 15 and 16 are diagrams showing the processing flow of the task dispatcher. FIG. 17 is a diagram showing the macro Diagram showing the processing flow of the processing program, No. 18
Figure 19 shows an example of task priority control, Figure 19 shows the state transition of tasks in the task priority control, Figure 20 shows the specific flow in Figure 12, and Figure 21. 22 is a diagram showing the hot wire output voltage acquisition timing, FIG. 22 is an INTL processing flowchart of intake air flow rate showing an embodiment of the present invention, and FIG. 23 is a compensation Q _A map diagram of compensation Q _A shown in FIG. 22. Figure 24 is a flowchart of the air amount signal processing task, Figure 25 is a diagram showing the soft timer table provided in the RAM, Figure 26 is a diagram showing the processing flow of the INTV interrupt processing program, and Figure 25 is a diagram showing the processing flow of the INTV interrupt processing program.
FIG. 7 is a timing chart showing how various tasks are started and stopped depending on the operating state of the engine, and FIG. 28 is an interrupt IRQ generation circuit. 24... Hot wire flowmeter, 2220... Hot wire resistor, 2221... Metal support, 2222... Insulating film, 2223... Linear resistor, 2224... Protective film, 2225... Electrode.

Claims (1)

[Claims] 1. A Wheatstone bridge is constructed by a hot wire heated by an electric current, a temperature compensation resistor, and two resistors, and a control current is applied so that the unbalanced voltage of the Wheatstone bridge is always zero. In a hot wire type flow sensor that controls the temperature of the hot wire at a constant temperature by flowing the hot wire, and detects a control current as an air flow rate to keep the temperature change of the hot wire constant due to changes in the air flow rate in the tube, the hot wire is made of a metal with high thermal conductivity. A hot wire flow rate sensor characterized in that it is formed by winding a wire resistor in a coil around a rod-shaped or tubular support coated with an insulating film. 2 In the invention described in claim 1,
The hot wire flow sensor is characterized in that the insulating film is made of an inorganic material such as ceramic or glass.