JPS61185647A - Intake pressure detecting device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent the operation performance and emission of an engine from becoming worse by providing a control means which performs a control action to change a change-over means from the side of an intake pipe to the side of the atmospheric pressure in the case where a fuel injection has been stopped and a brake has been pedaled. CONSTITUTION:A change-over means M2 supplies intake pressure and the atmospheric pressure with the mutual change-over of them to a pressure detecting means M1. When a detecting means for fuel supplying state M3 has detected a fuel supply to be stopped, and a detecting means for brake pedaling state M4 has also detected a brake to be pedaled, a control means M5 performs a control action to change the change-over means M2 from the side of an intake pipe to the side of the atmospheric pressure. Thus the operation performance and emission of an engine can be prevented from becoming worse.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake pressure detection device for an internal combustion engine, and more particularly to a device that detects intake pressure and atmospheric pressure using only one existing sensor.

[Prior art 1] Electronic fuel injection devices, particularly speed density type fuel injection control that calculates a basic fuel injection amount based on detection data of intake pipe pressure and engine speed of an internal combustion engine, e.g. The intake pipe pressure is detected by the intake pipe pressure sensor, and the engine rotation speed is detected by the engine rotation sensor, and the basic fuel injection amount is determined from the intake pipe pressure and the engine rotation speed.

However, this method does not directly detect the amount of intake air and instead uses the intake pipe pressure as data for air-fuel ratio control, making it difficult to unambiguously determine the conversion from intake pipe pressure to intake air amount. Therefore, it is difficult to calculate the optimum basic fuel injection amount depending on the engine operating state. This can be seen by considering the relationship between the intake pipe pressure and the intake air m using the following fluid model.
2g (PI - P2 ＞/γ. Here, A is the cross-sectional area of the pipe, m is the cross-sectional area ratio of the throttle to the pipe, α is the flow coefficient (the properties and velocity of the fluid, and γ is the Specific gravity, and Pl is the pressure inside the pipe upstream of the constriction part,
P2 is the pressure inside the pipe on the downstream side of the throttle portion. Therefore, from this equation, it is clear that the flow rate Q is not uniquely determined only by the value of P2, which corresponds to the intake pipe pressure,
For this reason, it is difficult to calculate a preferable basic fuel injection amount if the intake pipe pressure is simply used as input data by converting it into the intake air amount.

For these reasons, when controlling fuel injection using the speed density method, a third detection means, that is, atmospheric pressure detection means, is required to detect the value of Pl corresponding to atmospheric pressure and correct the fuel injection amount. I'll go.

FIG. 6 shows atmospheric pressure fluctuations and fuel correction amounts in a pressure detection type fuel injection device. As shown in the figure, the lower the atmospheric pressure and the lower the intake pipe internal pressure, the larger the correction amount.

Conventionally, there is a method of performing correction based on atmospheric pressure, for example, by separately providing a first detection means, that is, an intake pipe pressure sensor, and a second detection means, that is, an atmospheric pressure sensor. However, this method uses two pressure sensors, which increases the weight and
There were problems with deterioration of reliability and increase in cost.

As a means to solve this problem, JP-A-58-6
As seen in Publication No. 5950, a single pressure sensor installed in the intake pipe captures intake pipe pressure and atmospheric pressure information under different conditions, and the normally captured intake pipe pressure is corrected using the atmospheric pressure information. There is a method in which the engine is controlled using the pressure and engine rotation speed as parameters. In this method, as a condition for importing atmospheric pressure information, the pressure immediately after the engine's electronic control unit is initialized by turning on the power and when the throttle is almost fully opened is regarded as atmospheric pressure, and the popular pressure information is imported. Atmospheric pressure information could only be captured during a limited period of operation with the engine opening 4 and the throttle fully open.

In contrast, the publication date of Nippon Denso Technical Report is July 1, 1984.
As seen in reference number 36-036 on the 5th, a pressure switching valve is installed between the intake pipe and the pressure sensor, and the pressure switching valve is normally switched to the intake pipe side, and a certain delay time is set after the start of fuel cut. After that, there is a method in which the pressure switching valve is switched to the atmospheric side for a predetermined period of time, and during that time, atmospheric pressure is detected and atmospheric pressure correction is performed.

[Problems to be Solved by the Invention] By the way, in a system in which the pressure switching valve is switched to the atmospheric pressure side only during a fuel cut, the fuel cut may occur if the vehicle is re-accelerated during a fuel cut or during a slow gear change. If this happens, the switching valve will be switched from the atmosphere side to the intake pipe side when fuel injection starts, and the intake pressure that should be used will not be detected in time for the fuel injection control calculation when fuel injection starts, and the engine will not be able to detect the intake pressure in time for the fuel injection control calculation. There was a problem in that it became difficult to supply the amount of fuel, resulting in deterioration of drivability or emissions.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems and detect atmospheric pressure and intake pressure in a timely manner and more accurately.

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention employs the following configuration. That is, as shown in FIG. 1, pressure detection means M1 detects the pressure inside the intake pipe and the atmospheric pressure as data for calculating and correcting the amount of fuel supplied to the cylinders of the internal combustion engine EG of the vehicle; a switching means M2 for switching between and atmospheric pressure and supplying the same to the pressure detecting means M1; a fuel supply state detecting means M3 for detecting whether or not the fuel supply to the cylinder is stopped; a brake depression detecting means M4; The detection means M3 detects that the fuel injection is stopped, and the brake depression detection means M4
If it is detected that the brake is depressed by
An internal combustion engine characterized by comprising: a control means M5 for switching the switching means M2 to the atmospheric pressure side by 1.7J, and in other conditions, switching the switching means M2 to the intake pressure side. Its gist is an intake pressure detection device.

Here, the fuel supply state detection means M3 is means for detecting whether or not the fuel supply to the internal combustion engine EG is stopped. For example, this can be done by checking the fuel injection stop flag of the fuel injection control device or by determining the fuel injection stop conditions by yourself.

The brake depression detection means M4 is a means for detecting whether the brake is depressed or not.

For example, it can be detected by attaching a switch to the brake pedal.

[Function] That is, the intake pressure detection device of the present invention detects whether or not the fuel supply to the internal combustion engine FG is stopped using the fuel supply state detection means M3, and also detects whether or not the brake is depressed. When the detection is performed by the depression detection means M4 and the control means M5 uses the results of the fuel supply state detection means M3 and the brake depression detection means M4, and the result is that the fuel supply is stopped and the brake is being depressed. , the switching means M2 is controlled to switch from the intake pipe ■ side to the atmosphere side, and in other cases, it is controlled to switch from the atmosphere side to the intake pipe I side, so that only one pressure detection means M1 can be used to control the depression of the brake. After the release of , the detection of the intake pressure can be made possible by the time the accelerator pedal is depressed, at which time the detection of the intake pressure becomes necessary.

[Example] Next, an example of the present invention will be described with reference to FIGS. 2 to 8.

FIG. 2 shows a schematic configuration diagram of an internal combustion engine and its control system to which this embodiment is applied. 1 is a cylinder of a 6-cylinder internal combustion engine,
Reference numeral 2 denotes a pressure sensor for detecting the intake air pressure or atmospheric pressure in the intake pipe 3 connected to the cylinder 1, and is necessarily constituted by a semiconductor pressure sensor. 4 is an electromagnetically actuated fuel injection valve installed near each cylinder intake port of the intake pipe 3; 5 is an ignition coil forming part of an igniter; and 6 is a distributor connected to the ignition coil 5.

The rotor of this theme repeater 6 is 1/1/2 of the engine rotation.
The rotation sensor 7 is driven to rotate at a rotation speed of 2, and a rotation sensor 7 that outputs a signal indicating the engine rotation speed, fuel injection timing, and a cylinder discrimination signal is disposed inside. 9 is a throttle valve to the throttle valve 1, 10 is a throttle valve 9 opening, a throttle valve 1 to position sensor that detects the degree, 11 is a thermistor-type water temperature sensor that detects the engine cooling water temperature, and 12 is a sensor that detects the intake air temperature. The intake air temperature sensor 13 is an air-fuel ratio sensor provided in the exhaust manifold 14. This air-fuel ratio sensor] 3 detects the air-fuel ratio from the oxygen concentration in the exhaust gas soot, and sends a signal indicating this air-fuel ratio, for example, about 1 holt when the air-fuel ratio is close to the stoichiometric air-fuel ratio, and 0.1 when it is lean. small l
Outputs a voltage signal of -.

A solenoid valve 15 is provided between the pressure sensor 2 and the intake pipe 3. The electromagnetic valve has a three-way valve structure that functions to switch the pressure communicating with the pressure sensor to the intake pipe 3 side or the atmosphere side in response to a control signal from the control circuit 8. A brake depression detection device 16 detects whether the brake is depressed or not.

The brake depression detection device outputs a signal when the brake is depressed.

Reference numeral 8 denotes an electronic control circuit which controls the fuel injection amount of the internal combustion engine according to its operating state and controls the air-fuel ratio, and is constituted by a microcomputer. The control circuit 8 takes in detection signals from the pressure sensor 2, the rotation sensor 7, the throttle position sensor 10, the water temperature sensor 11, the intake temperature sensor 12, the air-fuel ratio sensor 13, and the brake pedal device 16, and uses these detection data. Based on this, the fuel injection amount is determined and the opening time of the fuel injection valve 4 is controlled to perform air-fuel ratio control.

FIG. 3 shows a block diagram of the control circuit 8 and each engine sensor, and 100 is an MPU (microprocessor unit) that executes arithmetic processing according to a predetermined program.
1 is an interrupt control unit that outputs an interrupt signal to the MPUI○O; 102 is a counter unit that counts the rotation angle signal from the rotation sensor 7 and calculates the engine rotation speed; 103
104 is an A/D that inputs the detection signal (analog signal) from the pressure sensor 2 and converts it into a digital signal.
Required in the conversion section. 105 is a ROM which is a read-only memory in which map data used for programs and calculations is stored in advance, and 106 is a RAM which is a readable and writable non-volatile memory and retains its stored contents even after the key switch is turned off. Reference numeral 107 denotes an output counter section for outputting an ignition timing control signal including a register, which takes in ignition timing data calculated by the MPU 100 and outputs an ignition timing control signal according to the crank angle. 108 is an output counter section for outputting a fuel injection amount (time) control signal including a register, which inputs fuel injection amount data sent from the MPU 100 and controls the opening time of the fuel injection valve 4 based on this data. Determine the duty ratio of the control pulse signal to
Outputs an injection amount control signal. The input port 120 receives a fully open throttle signal from the throttle position sensor 10 and receives a brake depression signal from the brake depression detection device 16 . The signal is used as data for atmospheric pressure correction in fuel injection amount calculation performed by the MPU 100. Note that the control signal output from the output counter section 107 or 108 is applied to the ignition coil 5 or the fuel injection valve 4 of each cylinder via the power amplifier 109, 110, respectively. The output port 121 outputs an energization signal from the MPU 100 that switches the solenoid valve 15 from the intake pipe 3 side to the atmosphere side. The energization signal is applied to the solenoid valve 15 via the power amplifier 22. Further, in the control circuit 8, an MPU 100, an interrupt control section 101, an input counter section 102, a digital input port 103, an A/D converter 1
04, ROM105, RAM106, output counter section 1
07.108, input port 120, and output port 121 are each connected to common bus 111, and necessary data transfer is performed according to instructions from MPU 100.

The rotation sensor 7 includes three sensors 71, 72, and 73,
The first rotation angle sensor 71 is operated at the timing shown in FIG.・−
As shown in (A>), the angle signal A is output at a predetermined angle 0 position from the crank angle O0 only once every revolution of the distributor 6, that is, every two revolutions of the crankshaft (720 degree angle). The second rotation angle sensor 72 generates an angle signal B once every two rotations of the crankshaft at a position a predetermined angle before 0 from the crank angle 3600.

The third rotation angle sensor 73 generates a number of angle signals equal to the number of cylinders at equal intervals for each rotation of the crankshaft. For example, in the case of a 6-cylinder engine, 6 angle signals are generated every 600 degrees from the crank angle 0°. Generate signal C.

The interrupt control unit 101 inputs these angle signals from the rotation sensor 7 and receives the angle signal C from the third rotation angle sensor 73.
A signal obtained by dividing the frequency of
Output to U100.

The output of this interrupt signal causes the MPU 100 to execute an arithmetic processing routine for ignition timing control. Roughly speaking, the interrupt control unit 101 divides the frequency of the angle signal C of the third rotation angle sensor 73 into six, and divides the signal obtained by dividing the frequency of the angle signal C of the third rotation angle sensor 73 into the angle signal A of the first rotation angle sensor 71 and the angle signal A of the second rotation angle sensor 72. An interrupt command signal E is generated every 360 degrees starting from the sixth point after the angle signal B is sent, that is, from the crank angle 300'.
Output to MPtJloo as . This interrupt command signal E issues an interrupt command to the MPU 100 to calculate the fuel injection amount.

Next, the operation of the intake pressure detection device of this embodiment will be explained with reference to FIGS. 5 to 8.

FIG. 5 shows a control flowchart for taking in atmospheric pressure during the main routine of the control circuit 8. This control routine is activated periodically along with other engine control programs. When this control routine is started, first in step 201, the engine speed is set to a predetermined value (for example, 1800 rpm).
pm) or more is determined, and if so, the process moves to step 202. This step 201
Low rotation speed just before injection return (e.g. 1800rl)
If this routine is performed with less than As shown in the logic diagram in Figure 7, the condition for cut 1 is when the throttle is closed and the engine speed is higher than a predetermined speed.This fuel cut effectively applies engine braking. During this time, calculation of the fuel injection amount is not necessary.If it is determined in step 202 that fuel is being cut, the process moves to step 203.In step 203, it is determined whether or not the brake is being depressed. If the brake is depressed, the process moves to step 204.Step 2
In 04, the time Ta (for example, 10 (m
s)) has elapsed and the time has elapsed (e.g. 400 (ms))
) is determined. If more than Ta has elapsed and less than Tb has elapsed since the brake pedal was depressed, the process moves to step 205.

In step 205, the electromagnetic valve 15 is turned on. The solenoid valve 15 is energized or turned on in step 205.
If it does, it will switch to the atmospheric side. Step 20
In step 5, after the electromagnetic valve 15 is energized "on", this control routine is temporarily terminated. If it is determined in step 201 that the engine speed is less than a predetermined value (for example, 1800 ppm>), the process moves to step 208, and after a reset start, the process moves to step 209, where the energization of the solenoid valve is turned off and the process ends. If it is determined in step 202 that the fuel is not being cut, the process moves to step 208, and step 20
After executing step 8, step 209 is executed and the process ends once. If it is determined in step 203 that the brake is not being depressed, the process moves to step 208, and after executing step 208, the process moves to step 209, and then ends once. In step 204, Ta (for example, 10
(ms)) or if more than Tb (for example, 400 (ms)) has elapsed,
At step 204, it is determined that it is rNOJ, and the process moves to step 206.

In step 206, the elapsed time after depressing the brake is Tb.
(For example, 400 (mS)) or more, it is determined whether or not. If the elapsed time is Tb or more, it is determined that rYEsJ, and the process moves to step 207. In step 207, the pressure is read from the pressure sensor 2 and the process is temporarily terminated. Step 207
The atmospheric pressure read in is used as atmospheric pressure correction data for calculating the fuel injection amount based on the graph shown in FIG. 6, which shows the relationship between atmospheric pressure and fuel correction ratio. If it is determined in step 206 that rNO1 has elapsed, that is, if less than the time Tb has elapsed since the brake pedal was depressed, the process moves to step 209, and after performing this operation, this routine is once terminated.

In the series of operations of this control, steps 201 and 202
．． After the condition of 203 is satisfied, T from pressing the brake.
a (for example, 10 (ms)), then close the solenoid valve 15 to the intake pipe 3.
switch from the side to the atmosphere side. Here, Ta (for example, 10 (
ms)) The reason why the solenoid valve 15 is switched after the lapse of time is to avoid malfunction due to electrical noise or the like. Time progresses roughly and -1 (for example, 400 (ms)) from the time of pressing the brake.
), read the atmospheric pressure using the pressure scanner 2. Here T
The reason why the atmospheric pressure is read after 400 (mS) elapses is to prevent malfunctions due to hunting of the solenoid valve 15, response of the pressure sensor 2, and delay due to the filter circuit for processing intake pulsation. . Reading of atmospheric pressure continues periodically as long as the conditions of steps 201 to 203 are satisfied, and when any of the conditions of steps 201 to 203 are no longer satisfied, the solenoid valve 15 is switched to the intake pipe 3 side. It will end once. Also, when the brake pedal is released at 6ff when reading the atmospheric pressure starts, the solenoid valve 15 is switched to the intake pipe 3 side and the process is temporarily terminated.

After switching the solenoid valve 15 to the intake pipe 3 side, fuel injection begins! ) Accurate intake pressure can be used for 1m calculation.

Next, the timing P t -1- of the main control shown in FIG. 8 will be explained.

In FIG. 8, time t1 is the engine speed or a predetermined value (for example, 18
00 rpm) or more. Time t2 is the time when the fuel cut state is entered from during fuel injection. Time t
3 is the point in time when the brake is depressed. Time t4 is the time when 51-8 hours have elapsed since the brake pedal was depressed. At this point, the condition of step 204 is satisfied and step 2
05, the energization of the solenoid valve 15 is turned on.

The solenoid valve 15 is switched from the intake pipe 3 side to the atmosphere side. When the solenoid valve 15 is switched to the atmospheric side in the above manner, atmospheric pressure is introduced into the pressure sensor 2. The pressure sensor 2 is t4
After a short delay, atmospheric pressure is detected. At time t5, time Tb has elapsed since the brake pedal was depressed. At this point, the condition in step 204 becomes rNOJ, and the process moves to step 206. In step 206, since the conditions are satisfied, rYESJ is determined, and the process moves to step 207, where the atmospheric pressure is read. After ↑5, the atmospheric pressure continues to be periodically read as long as the engine speed is above a predetermined value (for example, 1800 rpm), the fuel is being cut, and the brake pedal continues to be depressed. Time t6 is the time when the brake pedal is released while the solenoid valve 15 is switched to the atmosphere side.

At this point, the determination in step 203 is rNOJ, and the process moves to re-step 208, and after the reset and start operations, the process moves to step 209. In step 209, the energization of the solenoid valve 15 is turned off, and the solenoid valve 15 is switched from the atmosphere side to the intake pipe 3 side. The solenoid valve 15 is switched to the intake pipe 3 side, and the pressure sensor 2 enters the intake pressure detection state a little later than t6. This state is shown by a dotted line.

Time t7 indicates the time when the accelerator is depressed at which it is necessary to read the intake pressure after the brake depression is released at t6. t6
The time from 17 to 17 is the time required to switch the foot from the brake pedal to the accelerator pedal. In normal operation, it is 150 to 200 (ms). The dotted pressure curve indicates a state in which the intake pressure can be detected within the time it takes to switch the foot.

As described above, according to this embodiment, the atmospheric pressure required for calculating the fuel injection amount is detected when the fuel injection is stopped and when the brake is depressed, which does not require normal intake pressure detection. When it becomes necessary to calculate the fuel injection amount, the intake pressure can be detected immediately before it becomes necessary, so the accurate intake pressure necessary for calculating the fuel injection amount can be obtained at the beginning of normal operation. detection has been completed, and fuel injection amount calculation can be performed without any problem. In addition, by delaying the time Ta (for example, 10 (ms)) from the time the brake is depressed to switching the solenoid valve 15, and by delaying the time from reading the atmospheric pressure by Tb (for example, 400 (ms)), the solenoid valve 15 can be operated without malfunction. 15, it becomes possible to read accurate atmospheric pressure.

Furthermore, the engine speed determined in step 201 is less than the predetermined value.
By adding a conditional determination for the case where the engine speed exceeds 1800 rpm to this control routine, it is possible to prevent a stall during racing.

Further, in this embodiment, a method for correcting a deviation in the base air-fuel ratio has been described, but the present invention can also be used for correcting the amount of recirculation at high altitudes when an exhaust gas recirculation device is used.

[Effects of the Invention] As described above in detail with reference to the embodiments, the intake pressure detection device for an internal combustion engine of the present invention uses intake pressure as data for calculating and correcting the amount of fuel supplied to the cylinders of the internal combustion engine EG of a vehicle. Pressure detection means for detecting pressure inside the pipe and atmospheric pressure; Switching means for switching between intake pressure and atmospheric pressure and supplying the same to the pressure detection means; Fuel supply state detection means for detecting whether or not fuel supply to the cylinder is stopped. and a brake depression detection means; when the fuel supply state detection means detects that the fuel injection is stopped and the brake depression detection means detects that the brake depression state is detected, the switching means is set to atmospheric pressure. and control means for performing control for switching the switching means to the intake pressure side in any other state.

Therefore, the intake pressure and atmospheric pressure necessary for internal combustion engine operation can be detected with only one pressure sensor, and the control of the switching valve that switches between the intake pressure and atmospheric pressure applied to the pressure sensor can be controlled even when the fuel supply is stopped. By performing control to switch from the intake pipe side to the popular side only while the brake is depressed, the required intake pipe pressure can be accurately detected even at the beginning of the transition from the fuel supply stop state to the fuel supply state. This is an extremely excellent intake pressure detection device for internal combustion engines that can accurately perform pressure control using values.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram of an embodiment, FIG. 3 is a block diagram of its control system, and FIG. 4 is a timing chart of the angle signal output from the rotation sensor.
Fig. 5 is a flowchart of the solenoid valve switching control routine, Fig. 6 is a graph of the relationship between atmospheric pressure and combustion 1 correction ratio of the pressure detection type fuel injection device, Fig. 7 is a logic diagram of fuel cut, and Fig. 8 shows a timing chart of the solenoid valve switching control routine.・ Ml...Pressure detection means M2...Switching means M3...Fuel supply state detection means M4...Brake depression detection means M5...Control means EG...Internal combustion engine ■...Intake pipe 2 ... Pressure sensor 3 ... Intake pipe 8 ... Control circuit 15 ... Solenoid valve

Claims (1)

[Scope of Claims] Pressure detection means for detecting pressure in an intake pipe and atmospheric pressure as data for calculating and correcting the amount of fuel supplied to the cylinders of an internal combustion engine of a vehicle; and switching between the intake pressure and the atmospheric pressure. a switching means for supplying the fuel to the pressure detection means; a fuel supply state detection means for detecting whether or not the fuel supply to the cylinder is stopped; a brake depression detection means; and a switching means for detecting whether the fuel supply to the cylinder is stopped. When the brake depression state is detected and the brake depression state is detected by the brake depression detection means, the switching means is switched to the atmospheric pressure side, and in any other state, the switching means is controlled to be switched to the intake pressure side. An intake pressure detection device for an internal combustion engine, comprising: a control means;