JP3261087B2 - Engine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for controlling an internal combustion engine according to an in-cylinder pressure detection signal of the engine.

[0002]

2. Description of the Related Art It is known to use an in-cylinder pressure sensor for detecting a combustion pressure in a cylinder of an engine, that is, an in-cylinder pressure, in order to grasp an operating state of an internal combustion engine. The in-cylinder pressure sensor usually includes a ring-shaped piezoelectric element as shown in, for example, JP-A-8-50072, and the piezoelectric element includes a spark plug mounting seat surface of a cylinder head and a spark plug washer portion. And the spark plug is screwed into the cylinder head and fixed by pressure.

[0003] The in-cylinder pressure sensor generates an in-cylinder pressure detection signal corresponding to the in-cylinder pressure, and the signal is repeatedly read by an engine control circuit which is an arithmetic means. For the engine control.

[0004]

In order to accurately detect a change in the in-cylinder pressure and perform appropriate engine control, it is better to increase the number of reading samples, so that the crankshaft rotates, for example, once. Then, sampling of the output signal of the in-cylinder pressure sensor is performed. However, since the engine control circuit performs an operation for engine control in accordance with the in-cylinder pressure detection signal read at each sampling, when the engine speed increases to a high speed range, the read operation is performed as compared to when the engine speed is low. The operation period of the engine control circuit for one cylinder pressure detection signal becomes shorter,
A large load is applied to the engine control circuit. Therefore, in the engine control circuit, an expensive CPU, A /
There is a problem that a circuit element such as a D converter must be used.

Accordingly, an object of the present invention is to provide an engine control apparatus which does not need to use an expensive circuit element having a high processing speed in the arithmetic means even if the sampling cycle for reading the in-cylinder pressure detection signal is shortened due to an increase in the engine speed. It is to provide.

[0006]

[0007]

The engine control apparatus of the present invention SUMMARY OF THE INVENTION comprises a cylinder pressure detection means for generating a cylinder pressure detection signal corresponding to the pressure in the cylinder of a four-cycle internal combustion engine, detecting an engine speed of the internal combustion engine Means for detecting engine speed, means for comparing the engine speed detected by the engine speed detector with a predetermined speed, and means for generating a crank pulse each time the crankshaft of the internal combustion engine rotates by a predetermined angle. An operation of reading the in-cylinder pressure detection signal in synchronism with the crank pulse and calculating and outputting a control value of the internal combustion engine during the entire stroke of the internal combustion engine when the detected engine speed is equal to or lower than the predetermined speed. Means, means for controlling the internal combustion engine in accordance with the control value output from the arithmetic means, and intake stroke and exhaust stroke of the engine Means for learning and calculating and storing a learned value by learning a control value by an arithmetic means in the internal combustion engine when the detected engine speed is higher than a predetermined engine speed. In the expansion stroke, a cylinder pressure detection signal is read in synchronization with a crank pulse to calculate and output a control value, and a learning value is output as a control value in an intake stroke and an exhaust stroke of the internal combustion engine.

With this configuration, in the high engine speed region where the engine speed is higher than the predetermined speed, the in-cylinder pressure detection signal is not read in synchronization with the crank pulse during the intake stroke and the exhaust stroke, and the engine speed is set to the predetermined value. Since the engine control is performed using the value obtained as the learning value in the low engine speed range of the engine speed or less as the control value, the calculation processing load based on the in-cylinder pressure detection signal read per unit time is reduced.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an engine control device according to the present invention. In this engine control device, an intake pipe internal pressure sensor 3 (in-cylinder pressure detecting means) is provided downstream of a throttle valve 2 of an intake pipe 1 of a four-cycle internal combustion engine. The intake pipe pressure sensor 3 detects the pressure P in the intake pipe.
Detect _B.

An injector 4 is provided near the intake port of each cylinder (four cylinders in this embodiment) of the engine body 7. The injector 4 is driven by an ECU (engine control unit) 5 and injects fuel for the driven time. Note that only one cylinder is shown in FIG. Each cylinder of the engine body 7 is provided with an in-cylinder pressure sensor 6 for detecting the pressure in the cylinder. As shown in FIG. 2, each in-cylinder pressure sensor 6 for each cylinder includes a sensor element section 6a composed of a piezoelectric element and an amplification section that integrates (or averages) and amplifies the voltage generated from the sensor element section 6a. 6b.

As shown in FIG. 2, a spark plug 13 is screwed and fixed in a screw hole 12 of each cylinder head 11 of the engine body. Washer 13
The sensor element portion 6a of the in-cylinder pressure sensor 6 is sandwiched together with the washer 15 and fixed by pressure. ECU
5 is a CPU 31, ROM 32, RA
M33, A / D converter 34, actuator drive circuit 3
5 and counters 36 and 37, which are connected to each other by a common bus. A plurality of sensors are connected to the A / D converter 34, and an actuator such as an ignition device 41 is connected to the drive circuit 35 in addition to the injector 4. Although omitted in the figure, the injector 4 and the ignition device 41 are provided for each cylinder. A
As a sensor as operating state detecting means connected to the / D converter 34, in addition to the intake pipe internal pressure sensor 3 and the in-cylinder pressure sensor 6, a cooling water temperature sensor for detecting a cooling water temperature T _W of the internal combustion engine 42. There is an engine parameter sensor such as a throttle opening sensor (not shown) for detecting the opening of the throttle valve 2. Each time the crankshaft 8 rotates once, the A / D converter 34 converts the analog output voltage of each sensor into a digital value in a predetermined order, outputs the digital value for each sensor, and repeatedly updates the digital value. The counters 36 and 37 are supplied with crank pulses synchronized with each rotation of the crankshaft 8 from the crank angle sensor 38. The counter 36 and the crank angle sensor 38 together constitute an engine speed detecting means.
8 is measured by counting the number of clock pulse occurrences to determine the engine speed N
Generate a signal indicating e. The crank angle sensor 38 further generates a reference position signal indicating the time when the rotation angle of the crankshaft 8 is at a predetermined angular position and a TDC signal indicating the time of the top dead center of the piston of each cylinder. It is supplied to the CPU 31. The reference position signal is supplied to a counter 37, and the counter 37 is reset according to the reference position signal and counts pulses output from the crank angle sensor 38, and the counted value indicates the crank angle θ.

A CPU 31 of the ECU 5 operates in accordance with a program stored in a ROM 32 in advance, reads output values of a plurality of sensors via an A / D converter 34, and
Control values for driving the actuators such as the injector 4 and the ignition device 41, which are the engine control means, are stored in the AM 33 and calculated in accordance with the output values of the sensors. An example in which the engine control operation for calculating the control value is executed based on the in-cylinder pressure Pi obtained from the output signal of the in-cylinder pressure sensor 6 will be described below.

The CPU 31 repeatedly performs an engine control operation based on the in-cylinder pressure Pi in synchronization with a crank pulse. Although the engine control operation is performed for each cylinder, the same engine control operation is performed for any of the cylinders. Therefore, the engine control operation for one cylinder will be described here. In the engine control operation, the CPU 31 first reads the engine speed Ne from the counter 36 in synchronization with the crank pulse as shown in FIG.
1) It is determined whether or not the engine speed Ne is 3000 rpm or less (step S2). Ne ≦ 3000rpm
Then, the in-cylinder pressure Pi detected by the in-cylinder pressure sensor 6
Is read from the A / D converter 34 (step S3). N
If e> 3000 rpm, the engine speed Ne is 600
It is determined whether it is 0 rpm or less (step S4).
If Ne ≦ 6000 rpm, it is determined whether the reading of the in-cylinder pressure Pi was stopped last time (step S5). If the reading of the in-cylinder pressure Pi was stopped last time, the process proceeds to step S3, where the in-cylinder pressure Pi is read from the A / D converter 34, and if the reading of the in-cylinder pressure Pi was performed last time, this operation ends as it is. If Ne> 6000 rpm, it is determined whether the reading of the in-cylinder pressure Pi has been stopped twice consecutively (step S6). If the reading of the in-cylinder pressure Pi is stopped twice consecutively, the routine proceeds to step S3, where the in-cylinder pressure Pi is set to A / D
If the reading from the converter 34 has not been stopped twice and the reading of the in-cylinder pressure Pi has not been stopped two times, the operation ends.

After execution of step S3, the control value of the engine is calculated by using the read in-cylinder pressure Pi to calculate the control value (step S7). This control value is, for example,
This is a fuel injection time for injecting fuel by the injector 4, and a basic injection time is set from the intake pipe pressure P _B and the engine speed Ne, and the basic injection time is set to the cylinder pressure Pi.
And the fuel injection time is calculated. Step S
The control value calculated in step 7 is transmitted from the CPU 31 to the drive circuit 3 at an appropriate timing (for example, a timing at which fuel is injected).
5 and the drive circuit 35 drives an actuator such as the injector 4. The engine control is performed by repeating the above operation.

By executing the engine control operation in this manner, if the engine speed Ne is Ne ≦ 3000 rpm, the in-cylinder pressure Pi every time the crankshaft rotates once.
If 3000 rpm <Ne ≦ 6000 rpm, the cylinder pressure Pi is read every time the crankshaft rotates twice, and if Ne> 6000 rpm, the cylinder pressure Pi is read every time the crankshaft rotates three times. That is, the reading operation of the in-cylinder pressure Pi is thinned out as the engine speed increases and the engine speed becomes higher. Therefore, even if the engine speed rises above 3000 rpm, the calculation operation time of the engine control by the CPU 31 for one in-cylinder pressure Pi may be slightly longer than the time when the crankshaft rotates once, and the engine speed becomes 6000.
If the pressure rises above rpm, C for one cylinder pressure Pi
The calculation operation time of the engine control of the PU 31 may be slightly longer than the time that the crankshaft rotates twice.

In this embodiment, the crank pulse is always generated each time the crankshaft rotates once. However, if the engine speed Ne is Ne ≦ 3000 rpm, the crank pulse is generated every time the crankshaft rotates once. Generate a pulse and if 3000rpm <Ne ≦ 6000rpm,
A crank pulse is generated every time the crankshaft rotates twice, and if Ne> 6000 rpm, a crank pulse is generated every time the crankshaft rotates three times, and the in-cylinder pressure Pi is synchronized with the crank pulse. You may make it read.

In the embodiment shown in FIG.
Reference numeral 31 configures a comparison unit by executing step S2, configures a reading unit by performing steps S3 to S6, and configures a unit that controls the engine by performing step S7. FIG.
5 shows another engine control operation performed by the engine control system. In this engine control operation, the CP of the ECU 5
The U31 first reads the crank angle θ output from the counter 37 (step S11), takes in the engine speed Ne from the counter 36 (step S12),
When the engine speed Ne is equal to a predetermined speed N1 (for example, 3
000 rpm) is determined (step S13). If Ne ≦ N1, the engine is not in the high rotation state, and the in-cylinder pressure input process is performed in all the strokes (the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke). To A / D converter 3
4 (step S14), the control value of the engine is calculated by using the read in-cylinder pressure Pi to calculate the control value (step S15). This control value calculation operation is the same as in step S7 described above. Step S1
The control value calculated in step 5 is transmitted to the CPU 31 at appropriate timing.
Is supplied to the drive circuit 35, and the drive circuit 35 drives an actuator such as the injector 4 to control the engine.

After execution of step S15, the crank angle θ
Is within a predetermined angle range θ _{0 to} θ ₁ (step S16). Since the predetermined angle range theta ₀ through? ₁ corresponds to the intake stroke and the exhaust stroke of the cylinder, theta ₀
<A is satisfied theta <theta _1, the average value AVE is calculated the average value AVE of the control value in the current crank angle theta
Is written into the RAM 33 in correspondence with the current crank angle θ (step S17). The average value AVE is, for example, an average value of the control values at the same crank angle for five cycles.

In the above step S13, Ne> N
If it is 1, since the engine is in a high rotation state, the in-cylinder pressure is read during the compression stroke and the expansion stroke of all the strokes, so that the crank angle θ is an angle within a predetermined angle range θ _{0 to} θ ₁ . It is determined whether or not this is the case (step S18). θ ₀ <θ
If <θ ₁ is not satisfied, the compression stroke and the expansion stroke are performed, so the in-cylinder pressure P detected by the in-cylinder pressure sensor 6
i is read from the A / D converter 34 (step S1).
9) Using the read in-cylinder pressure Pi, the control value of the engine is calculated by calculating the control value (step S).
20). Steps S19 and S20 correspond to step S1.
4 and S15. In step S18, θ
₀ <theta <a is satisfied theta ₁ reads the average value AVE from RAM33 corresponding to the current crank angle theta (step S21). The read average value AVE is used as a control value of the current crank angle θ.

The control value calculated in step S15 or the control value read out in step S21 is supplied from the CPU 31 to the drive circuit 35 at an appropriate timing, and the drive circuit 35 drives an actuator such as the injector 4 or the like. By performing the in-cylinder pressure reading operation in this manner, if the engine speed Ne is Ne ≦ N1, every time the crankshaft rotates once in the entire stroke of the internal combustion engine (the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke). To the cylinder pressure Pi
Is read, and a control value is obtained by an arithmetic operation. In the intake stroke and the exhaust stroke, an average value AVE of the calculated control values is taken and stored in the RAM 33 in correspondence with the current crank angle θ.

If the engine rotation speed Ne is in a high rotation range where Ne> N1, the cylinder pressure Pi is read each time the crankshaft rotates once during the compression stroke and the expansion stroke of the internal combustion engine, and a control value is obtained by an arithmetic operation. Can be Since the reading of the in-cylinder pressure Pi is stopped during the intake stroke and the exhaust stroke, the calculation operation for obtaining the control value is not performed. In the intake stroke and the exhaust stroke, the average value AVE corresponding to the current crank angle θ is read from the RAM 33 and used as it is as the control value of the current crank angle θ.

In the embodiment of FIG. 5, the CPU
31 constitutes the comparing means by executing step S13, and constitutes the calculating means by executing steps S14, S15 and S18 to S21, and step S16
By executing S17 and S17, a learning value is calculated and stored.

[0023]

[0024]

As described above , according to the present invention, a crank generated every time the crankshaft rotates by a predetermined angle in the entire stroke of a four-cycle internal combustion engine when the detected engine speed is equal to or lower than a predetermined speed. The in-cylinder pressure detection signal is read in synchronization with the pulse, a learning value of the engine control value in the intake stroke and the exhaust stroke of the internal combustion engine is calculated and stored, and, on the other hand, the detected engine speed is larger than a predetermined speed. Sometimes, in the compression stroke and the expansion stroke of the internal combustion engine, the in-cylinder pressure detection signal is read in synchronization with the crank pulse, and the learned value is used in the intake stroke and the exhaust stroke of the internal combustion engine. in this way,
In the high engine speed range where the engine speed is higher than the predetermined speed, the in-cylinder pressure detection signal is not read in synchronization with the crank pulse during the intake stroke and the exhaust stroke, and the engine speed is lower than the predetermined speed. Since the value obtained as the learning value in the range is used, the calculation processing load based on the in-cylinder pressure detection signal read per unit time is reduced. Therefore, even if the sampling cycle of reading the in-cylinder pressure detection signal is shortened due to an increase in the engine speed, it is possible to avoid using expensive circuit elements having a high processing speed in the engine control circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an engine control device to which an embodiment of the present invention is applied.

FIG. 2 is a view showing an in-cylinder pressure sensor.

FIG. 3 is a block diagram showing a specific configuration of an ECU.

FIG. 4 is a flowchart showing an in-cylinder pressure reading operation.

FIG. 5 is a flowchart showing another in-cylinder pressure reading operation.

[Explanation of Signs of Main Parts]

 Reference Signs List 1 intake pipe 2 throttle valve 3 intake pipe internal pressure sensor 4 injector 5 ECU 6 cylinder internal pressure sensor 7 engine body 8 crankshaft 38 crank angle sensor 42 cooling water temperature sensor

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroaki Kato 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Hideyuki Oki 1-4-1 Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. (72) Inventor Yuichi Shimazaki 1-4-1, Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Kenji Abe 1-4-1, Chuo, Wako-shi, Saitama Pref. Inside Honda R & D Co., Ltd. (72) Inventor Shunichi Tsuzuki 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside Honda R & D Co., Ltd. (56) References JP-A-3-290043 (JP, A) JP JP-A-62-203036 (JP, A) JP-A-62-32263 (JP, A) JP-A-8-326572 (JP, A) JP-A-60-3462 (JP, A) JP-A 9-133042 (JP, A) , A) (58) Survey The field (Int.Cl. ^7, DB name) F02D 45/00 G01L 23/18

Claims (2)

(57) [Claims] 1. An in-cylinder pressure detecting means for generating an in-cylinder pressure detection signal according to a pressure in a cylinder of a four-cycle internal combustion engine; an engine speed detecting means for detecting an engine speed of the internal combustion engine; Comparing means for comparing the engine speed detected by the number detecting means with a predetermined speed; means for generating a crank pulse each time the crankshaft of the internal combustion engine rotates by a predetermined angle; and Calculating means for reading the in-cylinder pressure detection signal in synchronism with the crank pulse and calculating and outputting a control value of the internal combustion engine during the entire stroke of the internal combustion engine when the rotation speed is equal to or less than the predetermined rotational speed; Means for controlling the internal combustion engine according to the control value output from the engine, and an intake stroke and an exhaust stroke of the internal combustion engine Means for learning and calculating and storing a learned value by learning a control value by the arithmetic means in the internal combustion engine, wherein the arithmetic means is configured to execute the internal combustion when the detected engine speed is higher than the predetermined engine speed. In the compression stroke and the expansion stroke of the engine, the in-cylinder pressure detection signal is read in synchronization with the crank pulse, the control value is calculated and output, and the learning value is controlled in the intake stroke and the exhaust stroke of the internal combustion engine. An engine control device characterized by outputting as a value. Wherein said learning value engine control apparatus according to claim 1, characterized in that the average value of the control value in the intake stroke and an exhaust stroke of the internal combustion engine.