JP2000045857A - Engine cylinder pressure detector - Google Patents

Abstract

(57) [Problem] To provide an in-cylinder pressure detection device capable of detecting the in-cylinder pressure of an engine with high accuracy. A time constant of an integrating means for integrating a sensor signal corresponding to a pressure in a cylinder of an engine generated from a sensor element is changed in accordance with an engine parameter. The gain of the amplifying means for amplifying the sensor signal corresponding to the pressure in the cylinder of the engine generated from the sensor element is changed according to the engine parameter. An in-cylinder pressure detecting device that integrates the sensor signal by supplying a sensor signal corresponding to the pressure in the cylinder of the engine generated from the sensor element portion to the reactance element, during the intake stroke of the engine or near the start of the intake stroke. At this point, the reactance element is short-circuited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-cylinder pressure detecting device for detecting a pressure in a cylinder of an 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 the engine. The in-cylinder pressure sensor usually includes a ring-shaped piezoelectric element as shown in, for example, JP-A-8-50072.
The piezoelectric element is sandwiched between the ignition plug mounting seat surface of the cylinder head and the ignition plug washer, and the ignition plug is screwed and fixed to the cylinder head to be crimped and fixed.

An in-cylinder pressure sensor generates a signal indicating an in-cylinder pressure, and the signal is supplied to an engine control circuit and used as one parameter indicating an engine operating state for engine control such as a fuel injection amount and an ignition timing.

[0004]

However, the signal level generated by the piezoelectric element used in the in-cylinder pressure sensor not only changes in the in-cylinder pressure but also changes in the engine operating state such as engine load and engine temperature. Therefore, there is a problem that it is difficult to detect the in-cylinder pressure with high accuracy. More specifically, since the pyroelectric phenomenon or sensor output characteristics change with the temperature change of the piezoelectric element, especially after starting the engine, the characteristics of the in-cylinder pressure sensor change according to the engine temperature or engine load, so high accuracy It was difficult to detect the in-cylinder pressure.

An object of the present invention is to provide an in-cylinder pressure detecting device capable of detecting the in-cylinder pressure of an engine with high accuracy.

[0006]

According to the present invention, there is provided an in-cylinder pressure detecting device comprising: a sensor element for generating a sensor signal corresponding to a pressure in a cylinder of an engine; and an integrated signal obtained by integrating the sensor signal. Integrating means for outputting an internal pressure detection signal, operating state detecting means for detecting an engine parameter different from the pressure in the cylinder of the engine, and changing the time constant of the integrating means according to the engine parameter detected by the operating state detecting means And control means for causing the control unit to perform the control.

With this configuration, according to the present invention, the time constant of the integrating means for integrating the sensor signal corresponding to the pressure in the cylinder of the engine generated from the sensor element is changed in accordance with the engine parameter. The influence on the sensor element portion due to a change in the engine operation state such as the load and the engine temperature can be eliminated, and thus the in-cylinder pressure can be detected with high accuracy.

Further, the in-cylinder pressure detecting device of the present invention comprises a sensor element for generating a sensor signal corresponding to the pressure in the cylinder of the engine, and an amplified signal obtained by amplifying the sensor signal as an in-cylinder pressure detection signal. Amplifying means for outputting, operating state detecting means for detecting an engine parameter different from the pressure in the cylinder of the engine, and control means for changing a gain of the amplifying means in accordance with the engine parameter detected by the operating state detecting means. It is characterized by having.

With this configuration, according to the present invention, the gain of the amplifying means for amplifying the sensor signal according to the pressure in the cylinder of the engine generated from the sensor element portion is changed in accordance with the engine parameter. The influence on the sensor element portion due to a change in the engine operating state such as the engine temperature and the like can be eliminated, the detection sensitivity can be made appropriate, and the in-cylinder pressure can be detected with high accuracy.

Further, the in-cylinder pressure detecting device of the present invention is obtained by integrating a sensor signal by supplying a sensor signal to a reactance element and a sensor element for generating a sensor signal corresponding to the pressure in the cylinder of the engine. Integrating means for outputting the obtained integral signal as an in-cylinder pressure detection signal, and control means for short-circuiting the reactance element during or near the start of the intake stroke of the engine. TDC indicating the dead point arrival time
A timer for starting the time measurement in response to the signal, a means for setting a reset start time according to the engine speed of the engine and an intake pipe pressure downstream of the throttle valve, and a timer for setting the reset start time set by the timer. Means for short-circuiting the reactance element when the operation is completed.

With this configuration, according to the present invention, there is provided an in-cylinder pressure detecting device for integrating a sensor signal by supplying a sensor signal corresponding to a pressure in an engine cylinder generated from a sensor element portion to a reactance element. In response to the TDC signal indicating the time when the top dead center of the engine piston has been reached, the timer measures the engine rotation speed of the engine and the reset start time according to the pressure in the intake pipe downstream of the throttle valve. However, since the reactance element is short-circuited during or near the start of the intake stroke of the engine, the electric charge accumulated in the reactance element is discharged, and a stable in-cylinder pressure detection signal can be obtained. Therefore, the in-cylinder pressure can be detected with high accuracy.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an engine control device to which an in-cylinder pressure device according to the present invention is applied. Cylinder pressure sensor 1 ₁ to 1 ₄ for use in the engine control device,
It is provided for each cylinder of an internal combustion engine having a plurality of cylinders (four cylinders in this embodiment). Cylinder pressure sensor ₁ 1
Since 1 ₄ each structure is the same, and specifically shows the cylinder pressure sensor 1 ₁ in Figure 1. Cylinder pressure sensor ₁ 1
1 ₄ each having a sensor element 2 made of a piezoelectric element, and an amplifier section 3 for amplifying the voltage generated from the sensor element 2.

As shown in FIG. 2, a spark plug 7 is screwed and fixed in a screw hole 6 of each cylinder head 5 of the engine body, and a spark plug mounting seat surface 8 of the cylinder head 5 and its spark plug washer portion. 7a, the sensor element 2 of the in-cylinder pressure sensor 1 is sandwiched together with the washer 9 and fixed by crimping. The amplifying unit 3 connected to the output of the sensor element unit 2 includes an integrating circuit 11 for integrating a voltage signal (sensor signal) generated by the sensor element unit 2 and an integrating circuit 1
And a non-inverting amplifier circuit 12 for voltage-amplifying the signal output from 1 and outputting the amplified signal as an in-cylinder pressure detection signal. The integration circuit 11 includes a differential amplifier 13, resistors 14, 15 and a capacitor 16. The resistor 14 is an input resistor that supplies the output voltage from the sensor element unit 2 to the inverting input terminal of the differential amplifier 13. The resistor 15 and the capacitor 16 are connected in parallel between the inverting input terminal and the output terminal of the differential amplifier 13. It is connected to the. The non-inverting input terminal of the differential amplifier 13 is grounded. The resistance of the resistor 15 is variable, and the capacitance of the capacitor 16 is variable. The resistance value of the resistor 15 and the capacitance of the capacitor 16 determine the time constant τ of the integration circuit 11 and are initially set to a predetermined value. However, a control circuit (control means) 20 for engine control is used.
It is controlled in response to a command from

The non-inverting amplifier circuit 12 includes a differential amplifier 21 and resistors 22 to 24. The resistor 22 is connected between the output terminal of the differential amplifier 13 which is the output of the integrating circuit 11 and the non-inverting input terminal of the differential amplifier 21.
Is connected between the inverting input terminal of the differential amplifier 21 and the ground, and the resistor 24 is connected between the inverting input terminal and the output terminal of the differential amplifier 21. This non-inverting amplifier circuit 12
The output terminal of the differential amplifier 21 which is the output of
It is connected to the.

The control circuit 20 has a CPU as shown in FIG.
31, ROM 32, RAM 33, A / D converter 34,
Actuator 35, control signal generator 36,
At least a counter 37 is provided,
Connected to each other. A / D converter 34 has multiple
Are connected, and the driving circuit 35 has the injector 4
3. An actuator such as an ignition device 44 is connected. Figure
Although omitted, the injector 43 and the ignition device 4
Reference numeral 4 is provided for each cylinder. Connect to A / D converter 34
The sensor as the operating state detecting means is
In addition to the in-cylinder pressure sensor, throttle valves for internal combustion engines
(Not shown) Pressure P in the intake pipe downstream of _BDepending on the
Intake pipe internal pressure sensor 41 that generates pressure,
Temperature T_WSuch as the cooling water temperature sensor 42 for detecting
There is a gin parameter sensor. The A / D converter 34 is
For example, each time the link shaft rotates once,
Convert the analog output voltage to a digital value in a predetermined order
Outputs for each sensor and updates its digital value repeatedly
You. The control signal generation circuit 36 responds to a command from the CPU 31.
The resistance value of the resistor 15 and the capacitance of the capacitor 16
Generate a control signal to control the quantity. Counter 37
A signal synchronized with the rotation of the crankshaft from the rank angle sensor 38
Ruth is supplied. The counter 37 is a crank angle sensor 3
8 is the time interval of the clock pulse
The engine speed Ne is measured by counting the number of occurrences.
Generate a signal. The crank angle sensor 38 detects the crank angle.
Each air position together with a reference position signal indicating a point in time at a predetermined angular position.
A TDC signal indicating the top dead center of the cylinder piston is also generated,
These are supplied to the CPU 31.

The CPU 31 of the control circuit 20 includes a ROM 32
Operates in accordance with a program stored in advance in the A / D converter, reads the output values of the plurality of sensors via the A / D converter 34, stores them in the RAM 33, and according to the output values of the sensors, such as the injector 43 and the ignition device 44. A signal for driving the actuator is generated and supplied to the drive circuit 35.

As shown in FIG. 4, the CPU 31 of the control circuit 20 reads the engine speed Ne from the counter 37 every predetermined cycle (for example, a cycle in which the crankshaft rotates once) (step S1). The time constant τ of the integration circuit 11 corresponding to the number Ne is selected and set from a first time constant data map stored in the ROM 32 in advance (step S2). The relationship between the engine speed Ne and the time constant τ is shown in FIG.
As shown in (2), the time constant τ is set smaller as the engine speed Ne increases. This is because the higher the engine speed Ne, the shorter the control cycle using the in-cylinder pressure, but the change in the in-cylinder pressure in one cycle is also steep, so that the amplifier output responsiveness of the in-cylinder pressure sensor is required. First
The time constant τ set using the time constant data map is set to indicate the resistance value of the resistor 15 and the capacitance of the capacitor 16. After execution of step S2, the CPU 31
A time constant control command is issued to the control signal generation circuit 36 so as to control the time constant to the set time constant τ (step S3).

The control signal generating circuit 36 generates a control signal for the resistor 15 and the capacitor 16 in response to a time constant control command from the CPU 31 and sets the resistance value of the resistor 15 and the capacity of the capacitor 16 to a set time constant τ. It is changed so that it becomes. The integrating circuit 11 integrates the voltage signal from the sensor element unit 2 with a time constant τ, and the integrated voltage signal is amplified by the non-inverting amplifier circuit 12 and supplied to the control circuit 20 as an in-cylinder pressure detection signal indicating the in-cylinder pressure. You. Therefore, the in-cylinder pressure detection signal indicating the in-cylinder pressure supplied to the control circuit 20 has a value adapted to the operating state such as the engine load.

In the above-described embodiment, it is possible to control the same time constant at the same time for all cylinders. However, if the above-described steps S1 to S3 are executed at a timing synchronized with the TDC signal for each cylinder, In addition, time constant control can be performed for each cylinder. Further, when the engine is started, the cooling water temperature Tw measured by the cooling water temperature sensor 42 during the period until the warm-up of the engine is completed when the engine is started.
, The time constant τ by the resistor 15 and the capacitor 16 is controlled. In this case, as shown in FIG. 6, the CPU 31 reads the cooling water temperature Tw from the A / D converter 34 at a predetermined cycle (constant time) (step S11), and obtains the current value Tw.
variation ΔT = Tw _n -Tw _n-1 of _n and the previous value Tw _n-1 it is determined whether or not a predetermined value or more T1 (step S1
2). If .DELTA.T.gtoreq.T1, the time constant .tau. Of the integrating circuit 11 corresponding to the difference .DELTA.T is selected and set from the second time constant data map stored in the ROM 32 in advance (step S13).
As shown in FIG. 7, the relationship between the amount of change ΔT in cooling water temperature per unit time and the time constant τ is such that the larger the amount of change ΔT is, the smaller the time constant τ is set. This is because it is necessary to set the time constant to some extent (about 300 msec) to obtain a stable output characteristic because the change in the engine temperature is large and the sensor output characteristic changes when the engine is started. This is because when the change becomes smaller, it is necessary to accurately and quickly detect the in-cylinder pressure.
Also, as shown in FIG. 8, the output characteristic of the sensor element portion 2 changes greatly as the temperature change amount increases. In addition,
The output characteristics in FIG. 8 are under the condition that the sensor input pressure is constant. The time constant τ set using the second time constant data map is set to indicate the resistance value of the resistor 15 and the capacitance of the capacitor 16. CPU31
Issues a time constant control command to the control signal generation circuit 36 after the execution of step S13 so as to control the control signal generation circuit 36 to the set time constant τ (step S14).

The control signal generating circuit 36 generates a control signal for the resistor 15 and the capacitor 16 in response to a time constant control command from the CPU 31, and sets the resistance value of the resistor 15 and the capacitance of the capacitor 16 to a set time constant τ. It is changed so that it becomes. The integrating circuit 11 integrates the voltage signal from the sensor element unit 2 with a time constant τ, and the integrated voltage signal is amplified by the non-inverting amplifier circuit 12 and supplied to the control circuit 20 as an in-cylinder pressure detection signal indicating the in-cylinder pressure. You. Therefore, the in-cylinder pressure detection signal indicating the in-cylinder pressure supplied to the control circuit 20 has a value adapted to the engine temperature.

FIG. 9 further shows an engine control device to which the in-cylinder pressure sensor according to the present invention is applied. In the integrating circuit 11 of the amplifying unit 3 of the in-cylinder pressure sensor 1 ₁ used for the engine control device, the resistance 15 and the capacitor 16 in the case of FIG. 1 had become variably, in the case of FIG. 9 The resistance value of the resistor 15 and the capacitance of the capacitor 16 are both fixed. On the other hand, in the non-inverting amplifier circuit 12, a resistor 24 connected between the inverting input terminal and the output terminal of the differential amplifier 21 has a variable resistance value. The resistance value of the resistor 24 determines the gain of the non-inverting amplifier circuit 12 and is a value which is set in advance in advance, but is controlled according to a control signal from the control circuit 20 for engine control. That is, the control output of the control signal generation circuit 36 in the control circuit 20 of FIG. 3 is supplied to the resistor 24 instead of the resistor 15 and the capacitor 16. Other configurations are the same as those of the device of FIG. 1, and the internal configuration of the control circuit 20 is also as shown in FIG.

As shown in FIG. 10, the CPU 31 of the control circuit 20 reads the engine speed Ne from the counter 37 every predetermined cycle (for example, a cycle in which the crankshaft rotates once) (step S21), and reads the intake pipe pressure. the P _B a / D
The temperature is read from the converter 34 (step S22), and the cooling water temperature Tw is read from the A / D converter 34 (step S23). The gain G corresponding to the read engine speed Ne, intake pipe pressure P _B and cooling water temperature Tw is stored in a ROM.
32 is selected and set from the gain data map stored in advance (step S24). In this gain data map, in the case of the engine speed Ne, as shown in FIG.
Gain G decreases with increasing engine speed Ne, when the intake pipe pressure P _B, as shown in FIG. 12, the gain G is decreased as the intake pipe pressure P _B is increased, that is, changes in atmospheric pressure side, In the case of the cooling water temperature Tw, as shown in FIG. 13, the gain G is determined to decrease as the cooling water temperature Tw increases. The gain G set in the gain data map is set to indicate the resistance value of the resistor 24. After executing step S24, the CPU 31 issues a gain control command to the control signal generation circuit 36 so as to control the gain G set (step S25). Compensating for the change in the output characteristic of the in-cylinder pressure sensor according to the change in the engine temperature and the change in the output characteristic of the in-cylinder pressure sensor according to the engine cooling water temperature Tw caused by the increase in the intake pipe pressure P _B. Can be.

The control signal generation circuit 36 generates a control signal for the resistor 24 in response to a gain control command from the CPU 31, and varies the resistance value of the resistor 24 so that the gain G is set. A non-inverting amplifier circuit 12 to which a voltage obtained by integrating a voltage signal generated by the sensor element unit 2 is supplied from an integrating circuit 11
Then, the supply voltage signal is amplified by a gain G and supplied to the control circuit 20 as an in-cylinder pressure detection signal indicating the in-cylinder pressure.
Therefore, the in-cylinder pressure detection signal indicating the in-cylinder pressure supplied to the control circuit 20 has a value adapted to the operating state of the engine.

In the above-described embodiment, it is possible to control the same gain at the same time for all cylinders. However, if steps S21 to S25 are executed at the timing synchronized with the TDC signal for each cylinder, Gain control can be performed for each cylinder. FIG. 14 also shows an engine control device to which the in-cylinder pressure sensor according to the present invention is applied. In-cylinder pressure sensor 1 used in this engine control device
_In the integrating circuit 11 of the amplifying unit 3, the resistor 15 and the capacitor 16 can be changed in the case of FIG. 1, but the resistance value of the resistor 15 and the capacitance of the capacitor 16 are changed in the case of FIG. Both are fixed. Capacitor 16
A switch 17 is connected between both ends of the switch. This switch 17 discharges the electric charge stored in the capacitor 16 to determine the reference level of the in-cylinder pressure, and is normally in an off state.
ON / OFF control in response to a control signal from That is, the control output of the control signal generation circuit 36 in the control circuit 20 of FIG. 3 is supplied to the control terminal of the switch 17 instead of the resistor 15 and the capacitor 16. Other configurations are the same as those of the device of FIG. 1, and the internal configuration of the control circuit 20 is also as shown in FIG.

Each time the TDC signal is generated, the CPU 31 of the control circuit 20 starts a reset operation for turning on the switch 17 as shown in FIG. That is, first, the engine speed Ne is read from the counter 37 (step S31), and the intake pipe pressure P _B is read from the A / D converter 34 (step S32). The reset start time RT corresponding to these read engine rotational speed Ne and the intake pipe pressure P _B is selected and set from the previously stored reset data map in ROM 32 (step S3
3). In this reset data map, in the case of the engine speed Ne, as shown in FIG. 16, the reset start time RT becomes earlier as the engine speed Ne increases,
In the case of the intake pipe pressure P _B , as shown in FIG. 17, the reset start time RT is set to be earlier as the intake pipe pressure P _B increases, that is, changes to the atmospheric pressure side. This corresponds to the intake pipe pressure P _B and the engine speed Ne.
By changing the reset start timing according to the suction start timing changing as the intake air flow rate changes,
The in-cylinder pressure can be accurately integrated. The reset start time RT is a time from generation of a TDC signal for each cylinder to start of reset. After the reset start time is set, cylinder determination is performed (step S34),
It is determined whether or not the reset start time RT has elapsed since the generation of the TDC signal this time (step S35). The cylinder discrimination is performed by counting the number of TDC signals generated after the generation of the reference position signal. The cylinder obtained by the cylinder discrimination is defined as m. The determination of the elapse of the reset start time RT is performed by causing a timer to start measuring time each time a TDC signal is generated, and detecting that the measured time of the timer has reached the reset start time RT. The lapse of the reset start time RT is immediately before the start of the intake stroke or during the intake stroke in the cylinder m.

When the reset start time RT has elapsed, the CPU 31 issues an ON command to the control signal generating circuit 36 to turn on the switch 17 corresponding to the cylinder m (step S3).
6). The control signal generation circuit 36 generates a control signal for the switch 17 in response to an ON command from the CPU 31, and turns on the switch 17 corresponding to the cylinder m for a predetermined period. When the switch 17 is turned on, both ends of the capacitor 16 are short-circuited, and the electric charge accumulated in the capacitor 16 is discharged. Therefore, the output voltage level of the integration circuit 11 becomes the output voltage level of the sensor element section 2, and this voltage level becomes the reference level Pzero for detecting the in-cylinder pressure in the next compression stroke and the explosion stroke of the cylinder m. As shown in FIG. 18, the voltage P indicating the in-cylinder pressure supplied to the control circuit 20 is reset every time an ON command is generated, and then changes from a reference level Pzero determined according to the output voltage of the sensor element unit 2. You do it. The difference voltage between the voltage P and the reference level Pzero is detected as a voltage indicating the in-cylinder pressure.

In the above-described embodiment, the integration circuit using a capacitor is shown. However, the present invention is not limited to this, and an integration circuit using another reactance element such as a coil may be used. good.

[0028]

As described above, according to the present invention, the time constant of the integrating means for integrating the sensor signal according to the pressure in the cylinder of the engine generated from the sensor element is changed according to the engine parameters. In addition, it is possible to remove the influence on the sensor element portion due to a change in the engine operation state such as the engine load and the engine temperature, and thus it is possible to detect the in-cylinder pressure with high accuracy.

Further, according to the present invention, the gain of the amplifying means for amplifying the sensor signal corresponding to the pressure in the cylinder of the engine generated from the sensor element portion is changed in accordance with the engine parameter. The influence on the sensor element portion due to a change in the engine operating state such as temperature can be eliminated, and the detection sensitivity can be made appropriate, whereby the in-cylinder pressure can be detected with high accuracy.

Further, according to the present invention, there is provided an in-cylinder pressure detecting apparatus for integrating a sensor signal by supplying a sensor signal corresponding to a pressure in an engine cylinder generated from a sensor element portion to a reactance element. In response to the TDC signal indicating the top dead center of the piston, the timer measures the engine rotation speed of the engine and the reset start time according to the pressure in the intake pipe downstream of the throttle valve. Since the reactance element is reliably short-circuited during or near the start of the engine during the suction stroke of the engine during or near the start of the suction stroke, the electric charge accumulated in the reactance element is discharged and stable. An in-cylinder pressure detection signal can be obtained. Therefore, the in-cylinder pressure can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

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

FIG. 3 is a block diagram showing a configuration of a control circuit of the device shown in FIG.

FIG. 4 is a flowchart illustrating an operation of a CPU in a control circuit.

FIG. 5 is a diagram showing a relationship between an engine speed and a time constant.

FIG. 6 is a flowchart illustrating an operation of a CPU in the control circuit.

FIG. 7 is a diagram showing a relationship between a cooling water temperature and a time constant.

FIG. 8 is a characteristic showing an output change corresponding to a temperature change amount of the sensor element unit.

FIG. 9 is a block diagram showing an embodiment of the present invention.

FIG. 10 is a flowchart showing the operation of the CPU in the control circuit.

FIG. 11 is a diagram showing a relationship between an engine speed and a gain.

FIG. 12 is a diagram showing a relationship between an intake pipe pressure and a gain.

FIG. 13 is a diagram showing a relationship between a cooling water temperature and a gain.

FIG. 14 is a block diagram showing an embodiment of the present invention.

FIG. 15 is a flowchart illustrating an operation of a CPU in the control circuit.

FIG. 16 is a diagram showing a relationship between an engine speed and a reset start time.

FIG. 17 is a diagram showing a relationship between an intake pipe pressure and a reset start time.

FIG. 18 is a diagram showing a voltage level indicating an in-cylinder pressure supplied to a control circuit.

[Explanation of Signs of Main Parts]

 DESCRIPTION OF SYMBOLS 1 In-cylinder pressure sensor 2 Sensor element part 3 Amplification part 5 Cylinder head 6 Screw hole 7 Spark plug 7a Spark plug washer part 8 Spark plug mounting seat surface 11 Integration circuit 12 Non-inverting amplification circuit 20 Control circuit 31 CPU 34 A / D converter 36 Control signal generation circuit

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kenji Nakano 1-4-1 Chuo, Wako-shi, Saitama Pref. Wako Research Institute, Honda R & D Co., Ltd. (72) Hironao Fukuchi 1-chome, Chuo, Wako-shi, Saitama No.4-1 Inside Wako Laboratory, Honda R & D Co., Ltd. (72) Inventor Kazunori Sawamura 1-4-1, Chuo, Wako, Saitama Prefecture Inside Wako Lab., Honda R & D Co., Ltd. (72) Hideyuki Oki, Saitama 1-4-1, Chuo, Wako City, Wako Research Laboratory, Honda R & D Co., Ltd. (72) Inventor Hiroaki Kato 1-4-1, Chuo, Wako City, Saitama Prefecture, Wako Laboratory, Honda R & D Co., Ltd. (72) Inventor Kenji Abe 1-4-1 Chuo, Wako-shi, Saitama Pref. Wako Laboratory, Honda R & D Co., Ltd. (72) Inventor Takahiro Suzuki Mizuho, Nagoya-shi, Aichi 14-18 Takatsuji-cho, Ward-ku (72) Koji Okazaki 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi (72) Inventor Takeo Mizui 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi F-term (reference) 2F055 AA23 BB20 CC01 DD20 EE23 GG32 GG36 GG44 3G019 AA05 CA02 GA01 GA02 GA05 GA08 GA11 GA15 3G084 AA03 BA00 DA04 EA02 EA07 EB08 EB24 EC02 EC03 FA11 FA20 FA21 FA33 FA38 FA39

Claims (3)

[Claims] A sensor element for generating a sensor signal corresponding to a pressure in a cylinder of the engine; an integrating means for outputting an integrated signal obtained by integrating the sensor signal as a cylinder pressure detection signal; Operating state detecting means for detecting an engine parameter different from the pressure in the cylinder, and control means for changing a time constant of the integrating means in accordance with the engine parameter detected by the operating state detecting means. An in-cylinder pressure detection device characterized by the above-mentioned. 2. A sensor element for generating a sensor signal according to the pressure in a cylinder of an engine; an amplifying means for outputting an amplified signal obtained by amplifying the sensor signal as an in-cylinder pressure detection signal; Operating state detecting means for detecting an engine parameter different from the pressure in the cylinder, and control means for changing a gain of the amplifying means in accordance with the engine parameter detected by the operating state detecting means. Characteristic in-cylinder pressure detector. 3. A sensor element for generating a sensor signal corresponding to the pressure in a cylinder of an engine, and an integrated signal obtained by integrating the sensor signal by supplying the sensor signal to a reactance element. An in-cylinder pressure detection device comprising: an integration unit that outputs a detection signal; and a control unit that short-circuits the reactance element during a suction stroke of the engine or at a time near the start of the suction stroke. A timer for starting time measurement in response to a TDC signal indicating a time point at which the engine piston reaches the top dead center; and a means for setting a reset start time according to an engine speed of the engine and an intake pipe pressure downstream of a throttle valve. Means for short-circuiting the reactance element when the timer has finished measuring the set reset start time. Cylinder pressure detection device, characterized in that.