JP2000073846A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge the starting state by providing a determining means for determining the output of a cylinder pressure detecting means when an internal combustion engine is operated on a zero level. SOLUTION: This device is provided with a cylinder pressure detecting means for detecting the cylinder pressure Pn of an internal combustion engine, a zero level judging means for judging the zero level of the output of the cylinder pressure detecting means, and a determining means for determining the output of the cylinder pressure detecting means when the internal combustion engine is operated on the basis of the judged zero level. Accordingly, the output of the pressure sensor can be determined from the start of the internal combustion engine. Further, the starting state of an engine 10 is determined on the basis of the output of the cylinder pressure sensor 22 and when the completion of starting where the engine 10 is perfectly exploded is determined, a generating electric motor 12 is OFF to release the assist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine, and more particularly, to determine (correct or calibrate) the output of an in-cylinder pressure sensor in an internal combustion engine having motor assist means for assisting with an electric motor. About things.

[0002]

2. Description of the Related Art It is common to arrange an in-cylinder pressure sensor in an internal combustion engine to detect the in-cylinder pressure (combustion chamber pressure) to control the engine. However, since the sensor output fluctuates due to temperature drift, the engine is actually opened. In the technique described in Japanese Patent Application Laid-Open No. 60-131837, a correction value is calculated by measuring the output of the in-cylinder pressure sensor at the intake bottom dead center and the compression top dead center during fuel cut, and the calculated correction value is used to calculate other operating conditions. It has been proposed to correct the output of the in-cylinder pressure sensor at.

[0003] The present applicant also discloses Japanese Patent Application Laid-Open No. 62-19262.
Japanese Patent Application Laid-open No. 7-212,1992 proposes that the in-cylinder pressure sensor output during fuel cut is compared with a reference value to obtain a correction coefficient, and the calculated correction coefficient corrects the in-cylinder pressure sensor output in other operating states.

[0004] Apart from the above, recently, various internal combustion engines having motor assist means for assisting with an electric motor have been proposed.
Japanese Patent Application Laid-Open No. 95812 proposes a technique of detecting an in-cylinder pressure (combustion pressure) with an in-cylinder pressure sensor in an internal combustion engine having motor assist means and controlling an assist amount so as to suppress fluctuations in combustion pressure.

[0005]

In the internal combustion engine having such a motor assist means, when the output of the in-cylinder pressure sensor is determined (corrected or calibrated), the fuel cut state is determined according to the method proposed in the above-mentioned prior art. Until this occurs, in other words, until the engine starts and the vehicle runs, and the vehicle enters the cruise state, it cannot be performed.

Accordingly, the operating state is determined from the output of the in-cylinder pressure sensor,
For example, in order to determine the starting state of the engine, it is necessary to wait until the fuel cut state occurs.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned disadvantages of the prior art, and in an internal combustion engine provided with motor assist means, the output of an in-cylinder pressure sensor can be determined from the start of the internal combustion engine. An object of the present invention is to provide an engine control device.

Further, it is an additional object of the present invention to determine the output of the in-cylinder pressure sensor from the start of the internal combustion engine, and to determine the starting state of the internal combustion engine using the determined in-cylinder pressure sensor output. It is an object of the present invention to provide a control device for an internal combustion engine which enables the above.

[0009]

According to a first aspect of the present invention, there is provided an internal combustion engine having motor assist means for assisting with an electric motor, wherein the in-cylinder pressure of the internal combustion engine is detected. Cylinder pressure detecting means,
Zero level determining means for determining a zero level of the output of the in-cylinder pressure detecting means when assisted by the motor assist means; and the cylinder when the internal combustion engine is operating based on the determined zero level. It is configured to include a determination unit that determines the output of the internal pressure detection unit.

As described above, the zero level of the in-cylinder pressure sensor is determined when assisted by the motor assist means, and the sensor output is determined when the engine is operating based on the zero level. Can be determined.

Further, in order to solve the above-mentioned additional object, in an internal combustion engine having motor assist means for assisting with an electric motor, an in-cylinder pressure detecting means for detecting an in-cylinder pressure of the internal combustion engine, and the motor assist means When assisted by the motor assist means, when the assist is provided by the motor assist means, the start of the internal combustion engine is started in response to the start request of the internal combustion engine. Starting start means for starting, in-cylinder pressure determining means for determining an output of the in-cylinder pressure detecting means when the internal combustion engine starts starting based on the determined zero level, and an output of the determined in-cylinder pressure detecting means Engine starting state determining means for determining a starting state of the internal combustion engine based on Was composed as a motor assist canceling means for canceling the assistance by the motor assist unit.

Thus, the starting state is determined based on the determined in-cylinder pressure, in other words, the starting state is determined based on the combustion state, and the motor assist is performed until the combustion is determined to be stable. The internal combustion engine can be reliably started without increasing the supplied fuel amount at the time of starting. As a result, fuel efficiency and emission performance can be improved.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram generally showing a control device for an internal combustion engine according to the present invention.

In FIG. 1, reference numeral 10 denotes an OHC in-line four-cylinder internal combustion engine (hereinafter referred to as "engine"). A generator electric motor 1 is mounted on a crankshaft (not shown) of the engine 10.
2 is coaxially fixed and rotates in synchronization with rotation of the crankshaft.

As described above, the engine 10 is configured as an engine having motor assist means for assisting with the electric generator motor 12. The engine 10 is connected to an automatic transmission (T / M) 14 via the crankshaft described above.

The automatic transmission 14 changes the engine output,
The drive wheel 18 is rotated via the drive shaft 16. The automatic transmission 14 includes a shift controller (not shown) including a microcomputer, and a shift operation is controlled by the shift controller.

A mounting element for a spark plug (not shown) arranged at a position facing each cylinder combustion chamber (not shown) in the engine 10 accommodates a sensor element utilizing a piezoelectric effect. An in-cylinder pressure sensor (in-cylinder pressure detecting means) 22 constitutes an in-cylinder pressure (pressure in the combustion chamber) P
A signal (voltage) proportional to n (n: cylinder number) is output.

Camshaft of engine 10 (not shown)
, A signal corresponding to the piston crank angle position is output, and a water temperature sensor 26 is disposed in the cooling water passage of the cylinder block to output a signal corresponding to the engine cooling water temperature TW. .

An intake pipe of the engine 10 (not shown)
An absolute pressure sensor 28 is provided downstream of a throttle valve (not shown), and an intake pressure PBA downstream of the throttle valve is provided.
The throttle valve 30 is connected to the throttle valve and outputs a signal corresponding to the throttle opening θTH.

A vehicle speed sensor 32 is provided near the drive shaft, and outputs a signal every predetermined rotation of the drive shaft.

These sensor outputs are sent to a first electronic control unit (engine ECU) 40.

The engine ECU 40 has a CPU, ROM, R
The output of the camshaft sensor 24 and the vehicle speed sensor 32 is counted in the engine ECU 40 to calculate the engine speed NE and the vehicle speed V.

In the engine ECU 40, the CPU searches a map previously stored in the ROM based on the detected engine speed NE and the intake pipe absolute pressure PBA (engine load parameter), and determines the basic fuel injection amount and the basic fuel injection amount. The ignition timing is calculated, and the basic value calculated from the engine coolant temperature TW or the like is corrected to calculate the output fuel injection amount and the output ignition timing.

The CPU opens the injector (not shown) for a time corresponding to the output fuel injection amount calculated via the output circuit and the drive circuit (both not shown), and via the igniter (not shown). Then, the air-fuel mixture is ignited by the above-described ignition plug at the crank angle corresponding to the output ignition timing in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder, and burned.

The electric motor 12 has both functions of a generator and an electric motor, and is connected to a main battery 52 via a motor drive circuit 50. The motor drive circuit 50 includes a second electronic control unit (motor ECU) 54
And its operation is controlled.

The electric motor 12 is connected to the main battery 5.
2 functions as an electric motor that is energized and driven through a motor drive circuit 50, and functions as a generator when driven by an engine output (and during regenerative braking), and generates electric power through the motor drive circuit 50. To the main battery 52.

The motor ECU 54 also has a CPU, ROM, RA
M (not shown). When the operation of the system is started (system idle), the motor ECU 54 drives the electric generator motor 12 to rotate the crankshaft. Note that the motor ECU 54 is connected to the engine ECU 40 so as to be freely bidirectionally communicable.

In this specification, the term "system" refers to a so-called hybrid vehicle having the illustrated configuration including the engine 10 and the generator motor 12, and the term "system idle" refers to the case where the engine 10 is stopped and the generator motor is stopped. This means a state in which the motor 12 is turned on (operates) to start rotating the crankshaft.

When the start of the engine 10 is completed, the motor ECU 54 turns off (stops) the generator motor 12 through the motor drive circuit 50 so as to function as a generator, as described later.

Next, the operation of this apparatus will be described with reference to the flow chart of FIG. The operation of FIG. 2 shows the operation of determining the output of the in-cylinder pressure sensor and determining the engine start state based on the output. The illustrated program is executed by the engine ECU 40.

In the following, it is determined at S10 whether or not the system is idle. If the determination is negative, the subsequent processing is skipped. If the determination is affirmative, the process proceeds to S12 to determine whether there is an engine start request. to decide.

This engine start request is made in another routine (not shown), and the D range is selected by the automatic transmission 14,
When the vehicle speed V is 0 (when the vehicle is stopped) and the detected throttle opening θTH is less than a predetermined value (a value near full closure), an engine start request is made and the bit of a predetermined flag is set to 1. In this step, the determination is made by referring to the bit of the flag.

When the result in S12 is NO, the program proceeds to S14,
The generator motor 12 is kept on (driven).

When the result in S12 is affirmative, the program proceeds to S16,
Flag F. It is determined whether the bit (initial value 0) of SAISIDO is 1 or not. In the first program loop, the determination at S16 is denied, and the routine proceeds to S18, where the injection amount Ticr at the time of starting the engine is determined, and the injection is performed via the injector described above.

Thus, the engine 10 starts cranking. At this time, the generator electric motor 12 operates as a starter motor. In addition, the injection amount T at the time of starting is
icr is a fuel injection amount that does not include the start increment.

Then, the program proceeds to S20, in which the bit of the flag is set to "1". Therefore, setting the bit of this flag to 1 is equivalent to cranking (starting) of the engine 10.
Has started. If the result in S16 is affirmative, S18 and S20 are skipped.

Then, the program proceeds to S22, in which the average value (dp / dθ) ave of the in-cylinder pressure fluctuation calculated by sampling the output of the in-cylinder pressure sensor 22 in the processing of another routine is read.

FIG. 3 is a flowchart showing the processing. The illustrated program is executed by an angle interruption every 5 degrees of the crank angle in a range from a predetermined crank angle such as 10 degrees ATDC to 30 degrees BTDC.

Before starting the description of FIG. 3, the determination of the output of the in-cylinder pressure sensor 22 will be described.

As described above, the in-cylinder pressure sensor 22 composed of a piezoelectric element has a problem of temperature drift and also a problem of manufacturing variation. In particular, there is a problem of assembly variation, that is, the in-cylinder pressure sensor 22 is housed in a washer for mounting a spark plug. From
The sensor output differs depending on the tightening torque.

FIG. 4 is a simulation data diagram of the output waveform of the in-cylinder pressure sensor 22. In the figure, the vertical axis indicates the pressure Pn [MPa], but when converting the sensor output voltage into a pressure value at an earlier stage, it is necessary to determine the ground level (zero level, so-called background level) of the sensor output. is there.

Therefore, in this embodiment, FIG.
S15 is provided after S14 of the chart to determine the zero level. That is, the ground level (zero level) of the output voltage of the in-cylinder pressure sensor 22 is determined when the motor assist means is assisting.
More specifically, in FIG. 4, point A is determined as the ground level (zero level).

The following description is based on the premise of the above.
At 0, the output Pn of the in-cylinder pressure sensor 22 is sampled at every predetermined angle θ (the above-described crank angle of 5 degrees) in the combustion stroke of each cylinder. At this time, the sampling value is determined based on the zero level determined in S15 of FIG.

Next, the process proceeds to S102, and as shown in FIG.
In-cylinder pressure fluctuation amount during the corrected predetermined angle θ (dp / dθ)
Is calculated and stored. For convenience of understanding, dθ is exaggerated.

Then, the program proceeds to S104, in which a simple average value with respect to the previously calculated fluctuation amount (dp / dθ) is calculated, and is set as the average value (dp / dθ) of the in-cylinder pressure fluctuation amount.

As described above, in the process of FIG. 3, the in-cylinder pressure fluctuation amount of each cylinder is sequentially calculated at every 5 degrees of the crank angle, and then the average value is calculated with the calculated value.

Returning to the description of the flow chart of FIG. 2, the program proceeds to S24, in which operating parameters such as the detected engine speed NE and the engine cooling water temperature TW are read.
26, a map set as appropriate is retrieved from the read operation parameters, and a complete explosion determination threshold value (dp / dθ) i
Search for ndex.

Then, the program proceeds to S28, in which it is determined whether or not the average value (dp / dθ) ave of the read in-cylinder pressure variation exceeds the retrieved complete explosion determination threshold value (dp / dθ) index. That is, the engine (internal combustion engine) startup state is determined by determining whether or not the combustion has reached a state in which the in-cylinder pressure rises at a predetermined gradient or higher (corresponding to the complete explosion determination threshold value). judge.

When the result in S28 is affirmative, it is determined that the start of the engine 10 has been completed, and the program proceeds to S30, in which the generator motor 12 is turned off (stopped) to cancel the assist, and
If the result is negative, the process proceeds to S14, where the ON operation of the generator electric motor 12 is continued, and the zero level is determined in S15.

In this embodiment, as described above, the motor assist means (the second electronic control unit (motor ECU)) that assists with the electric motor (the electric motor 12).
54, a motor drive circuit 50), an in-cylinder pressure detecting means (in-cylinder pressure sensor 22, a first electronic control unit (engine ECU 40, S22, S100) for detecting an in-cylinder pressure Pn of the internal combustion engine. ),
Zero level determination means (engine ECU 40, S1) for determining a zero level (point A) of the output of the in-cylinder pressure detection means when assisted by the motor assist means.
5) and determining means (engine ECUs 40, S22, S22) for determining the output of the in-cylinder pressure detecting means when the internal combustion engine is operating based on the determined zero level.
100).

As described above, the zero level of the in-cylinder pressure sensor is determined when assisted by the motor assist means, and the sensor output is determined when the engine is operating based on the zero level. Can be determined.

Further, an electric motor (generator electric motor 1)
2) In an internal combustion engine (engine 10) having motor assist means (second electronic control unit (motor ECU) 54, motor drive circuit 50) for assisting by (2)
In-cylinder pressure detection means (in-cylinder pressure sensor 22, first electronic control unit (engine ECU) 40, S22, S100) for detecting in-cylinder pressure Pn of the internal combustion engine; Zero level determination means (engine ECU 40, S15) for determining a zero level (point A) of the output of the internal pressure detection means, when assisted by the motor assist means, starts the internal combustion engine in response to a start request for the internal combustion engine Starting means (first electronic control unit (engine ECU)
40, S10 to S20), an in-cylinder pressure determining means (engine E) for determining an output of the in-cylinder pressure detecting means when the internal combustion engine is operating based on the determined zero level.
CU40, S22, S100), engine starting state determining means (engine ECU 40, S100) for determining the starting state of the internal combustion engine based on the output of the determined in-cylinder pressure detecting means.
22 to S28) and a motor assist canceling means (engine ECU 40, S3) for canceling the assist by the motor assisting means according to the determined starting state.
0).

As described above, the starting state of the engine 10 is determined based on the output of the in-cylinder pressure sensor 22, and according to the determined starting state, that is, when it is determined that the engine 10 has completely exploded and the starting is completed. Turns off (stops) the generator electric motor 12 to cancel the assist.

That is, the combustion state is determined, and the motor assist is performed until it is determined that the combustion state is stable.
The engine 10 can be reliably started without increasing the fuel injection amount when the engine is started. Therefore, the engine can be reliably started without increasing the supplied fuel amount when the engine is started, and as a result, the fuel consumption performance and the emission performance can be improved.

In the above description, the in-cylinder pressure sensor 22 is provided for each cylinder, but may be provided for only one of the cylinders.

Although the average value of the in-cylinder pressure fluctuation amount is calculated with respect to the in-cylinder pressure fluctuation amount of the same cylinder, the average value with the in-cylinder pressure fluctuation amount of another cylinder may be calculated. Although the simple average is used, a moving average, a weighted average, or the like may be used.

Further, the starting state may be determined by comparing the in-cylinder pressure Pn with an appropriately set threshold value.

[0059]

According to the present invention, when assisted by the motor assist means, the zero level of the in-cylinder pressure sensor is determined, and the sensor output is determined at the time of engine operation based on the zero level. The output of the in-cylinder pressure sensor can be determined from the start.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an overall control device for an internal combustion engine according to the present invention.

FIG. 2 is a flowchart showing the operation of the apparatus in FIG. 1;

FIG. 3 is a flowchart showing an operation of calculating an average value of the in-cylinder pressure fluctuation amount performed in parallel with the flowchart of FIG. 2;

FIG. 4 is a simulation data diagram of in-cylinder pressure for explaining the determination of the in-cylinder pressure in the flowchart of FIG. 3;

[Explanation of symbols]

 Reference Signs List 10 internal combustion engine (engine) 12 electric generator motor (electric motor) 22 in-cylinder pressure sensor 40 first electronic control unit (engine ECU) 50 motor drive circuit 52 second electronic control unit (motor ECU)

Continued on the front page (72) Inventor Yoshitaka Kuroda 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside of Honda R & D Co., Ltd. (72) Inventor Kenji Abe 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. F-term in Honda R & D Co., Ltd. (reference) PA12 PG04 PI16 PI29 PO17 PU01 PU23 QI04 QN03 RE01 SE04 SE05 TE02 TE03 TE10

Claims (1)

[Claims] 1. An internal combustion engine having motor assist means for assisting with an electric motor, comprising: a. In-cylinder pressure detecting means for detecting the in-cylinder pressure of the internal combustion engine; b. Zero level determination means for determining a zero level of the output of the in-cylinder pressure detection means when assisted by the motor assist means; and c. A control device for an internal combustion engine, comprising: a determination unit that determines an output of the in-cylinder pressure detection unit when the internal combustion engine is operating based on the determined zero level.