JP5956532B2 - In-cylinder pressure detector - Google Patents

Description

  The present invention relates to an in-cylinder pressure detecting device that detects an in-cylinder pressure that is a pressure in a combustion chamber of an internal combustion engine. Relates to the device.

  Patent Document 1 includes a pressure detection element attached to an ignition plug or a fuel injection valve of an internal combustion engine, and an amplification circuit (charge amplifier) that amplifies a voltage change of the pressure detection element and outputs a pressure detection signal. A combustion pressure sensor is shown. In this combustion pressure sensor, the pressure detection element is fixed to the outside of the combustion chamber integrally with the fuel injection valve by, for example, a nut to which the fuel injection valve is attached, and the amplification circuit is integrated with the sensor fixing portion to which the pressure detection element is fixed. Provided.

  Patent Document 2 discloses an in-cylinder pressure detecting device in which a pressure detecting element is attached to the tip of a fuel injection valve that injects fuel into a combustion chamber, and the in-cylinder pressure is detected using the pressure detecting element.

Japanese Patent No. 4407004 International Publication WO2012 / 115036

  The combustion pressure sensor disclosed in Patent Document 1 requires room for improvement in terms of workability at the time of mounting because the sensor fixing portion needs to be sandwiched and fixed at the same time when the fuel injection valve is fixed. .

  Further, as shown in Patent Document 2, when the pressure detection element is disposed at the tip of the portion of the fuel injection valve that is inserted into the combustion chamber, the pressure detection element and the amplification circuit are disposed close to each other. It has been desired to realize the above with good workability.

  The present invention has been made paying attention to the above-mentioned points. A pressure detection element is attached to the tip of the fuel injection device (fuel injection valve) to detect the in-cylinder pressure, and to influence the drive signal of the fuel injection device. An object of the present invention is to provide an in-cylinder pressure detecting device that can reduce and improve workability when mounted on an internal combustion engine.

In order to achieve the above object, a first aspect of the present invention is directed to a pressure detection element (2) attached to a tip of a fuel injection device (1) for injecting fuel into a combustion chamber of an internal combustion engine, and the pressure detection element. And an amplifying circuit unit (11) including an amplifying circuit for amplifying a signal output from the output and outputting a pressure detection signal, and in the in-cylinder pressure detecting device for detecting the pressure in the combustion chamber, the pressure detecting element (2) And an in-cylinder pressure detecting unit (101) including the amplifying circuit unit (11) and a connecting member (12) for connecting the pressure detecting element and the amplifying circuit unit to the fuel injection device (1). Accordingly, constitute cylinder pressure detection unit with a fuel injection device (100), equipped with the cylinder pressure detecting unit with the fuel injection system to the internal combustion engine, the cylinder pressure detection unit (101), prior to A cylindrical sensor fixing member (13) having a pressure detection element (2) fixed at the tip thereof, the amplification circuit unit (11), and a connection member (12 for connecting the pressure detection element and the amplification circuit unit) ), And the sensor fixing member (13) is fitted into the front end (4) of the fuel injection device .

According to this configuration, the in-cylinder pressure detection unit with the in-cylinder pressure detection unit is configured by integrating the in-cylinder pressure detection unit including the pressure detection element, the amplification circuit unit, and the connecting member that connects them with the fuel injection device. Since the fuel injection device with the in-cylinder pressure detection unit is attached to the internal combustion engine, the influence of the drive signal of the fuel injection device is reduced by bringing the pressure detection element and the amplification circuit unit close to each other, and the in-cylinder pressure detection unit It becomes possible to mount the internal combustion engine by the same operation as that of the fuel injection device that is not mounted, and the workability can be improved. Furthermore, the cylinder fixing pressure sensor unit is configured by previously assembling the sensor fixing member, the amplification circuit unit, and the connecting member for connecting them, and the cylindrical sensor fixing member to which the pressure detecting element of the cylinder pressure detecting unit is fixed. Since the fuel injection device with the in-cylinder pressure detection unit is configured by being fitted to the tip of the fuel injection device, workability when the in-cylinder pressure detection unit is integrated with the fuel injection device can be improved.

Invention according to claim 2, in-cylinder pressure detection device according to claim 1, wherein the amplifier circuit unit (11), the fuel injection device from the control unit (60) for controlling the fuel injection device (1) The drive signal line for supplying a drive signal to the connector (51) is connected to the connector (51), and the connector (51) is a connection line between the amplifier circuit unit (11) and the control unit (60). The connection terminals (31 to 33) are included.

  According to this configuration, the connection terminal of the connection line between the amplifier circuit unit and the control unit is included in the connector to which the drive signal line of the fuel injection device is connected, so that the power supply to the amplifier circuit unit and the pressure are supplied. Transmission of the detection signal and transmission of the fuel injection device drive signal can be performed through a single connector, facilitating assembly work and miniaturization of the fuel injection device including the amplifier circuit unit. be able to.

The invention according to claim 3, in-cylinder pressure detection device according to claim 1, wherein the fuel injection device, the drive signal line is connected for supplying a drive signal from the control unit for controlling the fuel injection device (60) A main body connector portion (51a) having connection terminals (21 to 23) to be connected, and the in-cylinder pressure detection unit (101) is connected to a detection signal line for supplying the pressure detection signal to the control unit. A sub-connector portion (51b) having connection terminals (31 to 33) is provided, and the sub-connector portion (51b) is configured separately from the main body connector portion (51a).

  According to this configuration, the detection signal line through which the pressure detection signal is transmitted is separated from the drive signal line through which a relatively large current flows, and the influence of the drive signal on the in-cylinder pressure detection signal can be reduced.

According to a fourth aspect of the present invention, in the in-cylinder pressure detecting device according to any one of the first to third aspects, the amplification circuit unit (11) includes a drive circuit (24) for the fuel injection device. It is fixed to the outside of the metal casing (3) in a state covered with a molding material (10, 11a) or in a state accommodated in a metal case.

  According to this configuration, the amplifying circuit unit is fixed to the outside of the metal casing containing the drive circuit of the fuel injection device in a state covered with the molding material or accommodated in the metal case. It is easy to handle in an integrated state, and the effects of waterproofing, heat insulation, and insulation of the amplifier circuit can be obtained with certainty.

According to a fifth aspect of the present invention, in the in-cylinder pressure detecting device according to any one of the first to fourth aspects, the amplifier circuit unit (11) includes the amplifier circuit unit (11) and the pressure detection signal. A failure detection circuit (47) for diagnosing the connection state with the control unit (60) for supplying the control unit (60) is provided.
According to this configuration, the connection state between the amplifier circuit unit and the control unit that supplies the pressure detection signal can be diagnosed by the control unit by the failure detection circuit.

According to a sixth aspect of the present invention, in the in-cylinder pressure detecting device according to any one of the first to fifth aspects, the amplifier circuit unit (11) is a sensitivity adjustment circuit for performing sensitivity adjustment of the amplifier circuit. (46).

  According to this configuration, it is possible to perform sensitivity adjustment in a state where the pressure detection element and the amplifier circuit are combined before the in-cylinder pressure detection device is mounted on the engine. A pressure detection signal can be obtained by amplifying the output voltage of the pressure detection element while integrating it with an amplifier circuit, but it has been confirmed that the detection sensitivity varies due to variations in characteristics of the pressure detection element and the amplifier circuit. Therefore, by adjusting the gain of the amplification circuit in a state where the pressure detection element and the amplification circuit are combined, it is possible to eliminate the influence of variations in the characteristics of the pressure detection element and the amplification circuit and perform accurate pressure detection. .

A seventh aspect of the present invention is the in-cylinder pressure detecting device according to any one of the first to sixth aspects, wherein the amplifier circuit unit (11) is a noise superimposed on a power line (53) for supplying power. And / or a power supply noise filter (49) for removing noise superimposed on the pressure detection signal.
According to this configuration, it is possible to reliably prevent noise from being mixed into the pressure detection signal via the power line or directly.

The invention described in claim 8 is characterized in that, in the in-cylinder pressure detecting device according to any one of claims 1 to 7 , the amplification circuit unit (11) is configured on a flexible printed circuit board. To do.
According to this configuration, since the amplifier circuit unit is configured on the flexible printed wiring board, the amplifier circuit can be reduced in size and can be easily attached to the fuel injection device.

It is a perspective view which shows the fuel-injection apparatus with a cylinder pressure detection unit concerning the 1st Embodiment of this invention. It is a side view of the fuel-injection apparatus with a cylinder pressure detection unit shown in FIG. It is a figure for demonstrating the structure of the connection member shown in FIG. It is sectional drawing which shows the structure of the front-end | tip part vicinity of the fuel-injection apparatus with a cylinder pressure detection unit. It is a block diagram which shows the structure of the amplifier circuit unit shown in FIG. It is a figure for demonstrating the circuit for failure detection. It is a figure for demonstrating the connection of the drive solenoid of a fuel-injection apparatus, and an electronic control unit. It is a perspective view which shows the modification of the structure shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1A is a perspective view showing a fuel injection device with an in-cylinder pressure detection unit according to an embodiment of the present invention, and FIG. 1B is a diagram of the fuel injection device shown in FIG. It is a perspective view which shows a part changing a viewpoint. 2 (a) is a side view of the fuel injection device shown in FIG. 1 (a), and FIG. 2 (b) shows the fuel injection device shown in FIG. 2 (a) covered with a synthetic resin mold. FIG. FIG.1 and FIG.2 (a) has shown the state without a synthetic resin mold for description.

  The fuel injection device 100 with the in-cylinder pressure detection unit is configured by mounting the in-cylinder pressure detection unit 101 on the fuel injection device 1. In the present embodiment, the in-cylinder pressure of the internal combustion engine is detected by mounting the fuel injection device 100 with the in-cylinder pressure detection unit configured by integrating the in-cylinder pressure detection unit 101 to the fuel injection device 1 to the internal combustion engine.

  The fuel injection device 1 is a device that injects fuel into a combustion chamber of an internal combustion engine. Inside the valve body, which is a well-known component, a solenoid (drive circuit) that drives the valve body, a spring that biases the valve body, and the like The fuel is injected from the injection port 5 at the tip. The fuel injection device 1 includes a metal large-diameter portion casing 3 in which a solenoid is incorporated, and a metal small-diameter portion casing 4 provided with an injection port 5 at the tip.

  The in-cylinder pressure detection unit 101 connects the pressure detection element 2, the cylindrical sensor fixing member 13 with the pressure detection element 2 fixed to the tip, the amplification circuit unit 11, and the pressure detection element 2 and the amplification circuit unit 11. The in-cylinder pressure detection unit 101 is made to be fuel by inserting the sensor fixing member 13 into the distal end side (injection port 5 side) of the small diameter casing 4 of the fuel injection device 1. Mounted on the injection device 1. Therefore, the pressure detection element 2 is attached to the tip of the fuel injection device 1 (a position surrounding the injection port 5) and is connected to the amplifier circuit unit 11 by the connection member 12. The amplification circuit unit 11 is disposed at a position slightly away from the large diameter casing 3 of the fuel injection device 1, and the synthetic resin mold 10 is interposed between the amplification circuit unit 11 and the large diameter casing 3. (See FIG. 2 (b)).

  3A and 3B are diagrams for explaining the structure of the connecting member 12, in which FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along the line AA in FIG. The connecting member 12 has a structure known as a flexible wiring board configured by covering the copper wire 17 with the polyimide covering members 14 and 15 via the adhesive 16 (epoxy resin), and is disconnected. And can be bent easily. The connection member 12 is connected to the pressure detection element 2 in the vicinity of the distal end portion (the portion indicated by RIN in FIG. 3A) passes through the inside of the metal sensor fixing member 13 as shown in FIG. Between the vicinity part RIN and the amplifier circuit unit 11, it arrange | positions so that the outer peripheral surface of the large diameter part casing 3 of the fuel injection apparatus 1 may be followed. However, the connection portion vicinity portion 12 a with the amplifier circuit unit 11 is separated from the outer peripheral surface of the large diameter portion casing 3.

  The amplifier circuit unit 11 is shown in FIGS. 1 and 2 as being accommodated in a transparent case, but this is shown for the sake of explanation, and is actually mounted on a flexible printed circuit board. The parts are arranged and electrically connected, and the whole is covered with the synthetic resin mold 11a. Therefore, in the following description, it is called “synthetic resin mold 11a”.

  Connector pins 31 to 33 are fixed to the amplifying circuit unit 11, and the connector pins 31 to 33 are connector pins to which drive signal lines for supplying drive signals to the solenoid (drive circuit) of the fuel injection device 1 are connected. A part of connector part 51 is constituted with 21-23. A connector member that can be fitted to the connector pins 21 to 23 and 31 to 33 of the connector 51 is connected from an electronic control unit (hereinafter referred to as “ECU”) 60 (see FIGS. 5 and 7) that controls the fuel injection device 1. The connecting wire and each of the connector pins 21 to 23 and 31 to 33 are connected by being fixed to the tip of the wire and fitting the connector member.

  The amplifier circuit unit 11 and the connection member 12 are covered with a synthetic resin mold 10 and fixed to the fuel injection device 1 as shown in FIG. In the ranges RM1 and RM2 shown in FIG. 2B, the entire periphery of the fuel injection device 1 is covered with the synthetic resin mold 10, and in the range RM3, the vicinity of the amplifier circuit unit 11 and the connection member 12 is covered. Further, as shown in FIG. 2C, the connector pins 51 to 23 and 31 to 33 are exposed, and a connector member (not shown) fixed to the distal end portion of the connection line can be fitted. It is configured. FIG.2 (c) is the figure which looked at the connector part 51 from the direction shown by the arrow B of FIG.2 (b).

  FIG. 5 is a block diagram showing the configuration of the amplifier circuit unit 11. The amplifier circuit unit 11 includes a capacitor 41, a low-pass filter 42, a charge amplifier 43, a high-pass filter 44, an amplifier circuit 45, a sensitivity adjustment circuit 46, and a failure detection circuit. 47, a reference voltage circuit 48, a power supply noise filter 49, an AC grounding capacitor 50, and connector pins 31 to 33 constituting the connector unit 51. The connector pin 31 is connected to the ground of the ECU 60 via the ground connection line 61, the DC power supply voltage (for example, 5V) is supplied to the connector pin 32 via the power supply connection line 62, and the connector pin 33 is connected to the signal connection line (detection). Signal line) 63 is connected to the AD converter of ECU 60. The power line 53 connected to the connector pin 32 is connected to the reference voltage circuit 48 via the power noise filter 49.

  The capacitor 41 cuts the DC component of the input detection signal from the pressure detection element 2 through the connection member 12, and only the AC component of the input detection signal is input to the low-pass filter 42. The low pass filter 42 attenuates unnecessary high frequency components. The charge amplifier 43 converts the input signal indicating the pressure change rate into a pressure signal indicating the pressure value by amplifying the input signal while integrating the input signal. The high pass filter 44 attenuates unnecessary low frequency components. The amplifier circuit 45 amplifies the output signal of the high pass filter 44.

  The sensitivity adjustment circuit 46 is composed of, for example, a combination of a plurality of resistance elements, and the output signal level of the amplification circuit 45 when the pressure detection element 2 is connected and a test pressure is applied to the pressure detection element 2 is predetermined. This is a circuit for adjusting the gain of the amplifier circuit 45 so as to be at the level. Specifically, the resistance value as a whole is adjusted by cutting a wiring connecting a plurality of resistance elements mounted in advance, and gain adjustment is performed. This gain adjustment is performed before the amplification circuit unit 11 is covered with the synthetic resin mold 11a.

  The reference voltage circuit 48 generates a reference voltage VREF from the power supply voltage VS1 supplied from the ECU 60 and supplies the reference voltage VREF to the charge amplifier 43, the high-pass filter 44, and the amplifier circuit 45. The reference voltage VREF is a voltage for offsetting the DC voltage (raising 0V to 1V). The power supply noise filter 49 is a low-pass filter that removes noise mixed through the power supply connection line 62.

  The ground line 52 of the amplifier circuit unit 11 is connected to the ground of the ECU 60 via the connector portion 51 and the ground connection line 61, but is connected to the casing of the fuel injection device 1 via the AC grounding capacitor 50. However, it is not connected to the casing of the fuel injection device 1 in terms of direct current. As a result, the disconnection of the ground connection line 61 can be detected by the ECU 60 as described below. Note that the housing of the fuel injection device 1 is electrically connected to the cylinder head of the internal combustion engine.

  The failure detection circuit 47 is configured by connecting a pull-up resistor RPU to the power supply line LS as shown in FIG. The ECU 60 is provided with a pull-down resistor RPD connected to the ground. The power connection line 62 or the signal connection line 63 is disconnected or grounded (short-circuited with the ground) or the ground connection line 61 according to the input DC voltage VIN. The disconnection is configured to be detectable. That is, when the connection line 62 or 63 is disconnected or a ground fault occurs, the input DC voltage VIN becomes “0”, and when the ground connection line 61 is disconnected, the input DC voltage VIN becomes higher than the normal voltage VNL. Therefore, when the input DC voltage VIN is higher than the normal voltage VNL by a predetermined voltage or higher, it can be determined that the ground connection line 61 is disconnected.

  FIG. 7 is a diagram for explaining the connection between the drive solenoid 24 of the fuel injection device 1 and the ECU 60. Both ends of the solenoid 24 are connected to the ECU 60 via the connector pins 22 and 23 of the connector portion 51. The connector pin 21 is grounded to the housing in the fuel injection device 1.

  As described above, in the present embodiment, the in-cylinder pressure detection unit 101 is integrated with the fuel injection device 1 by integrating the in-cylinder pressure detection unit 101 including the pressure detection element 2, the amplifier circuit unit 11, and the connection member 12 connecting them. The fuel injection device 100 with a cylinder is configured, and the fuel injection device 100 with the in-cylinder pressure detection unit is mounted on the internal combustion engine, so that the fuel injection device 1 is driven by bringing the pressure detection element 2 and the amplification circuit unit 11 close to each other. In addition to reducing the influence of the signal, it can be mounted on the internal combustion engine by the same operation as that of the fuel injection device in which the in-cylinder pressure detection unit 101 is not mounted, and the workability at the time of mounting can be improved.

  Further, the in-cylinder pressure detection unit 101 is configured by assembling in advance the cylindrical sensor fixing member 13 to which the pressure detection element 2 is fixed, the amplification circuit unit 11, and the connection member 12 that connects the pressure detection element 2 and the amplification circuit unit 11. The in-cylinder pressure detection unit 101 is configured to fit the cylindrical sensor fixing member 13 into the tip of the fuel injection device 1, whereby the fuel injection device 100 with the in-cylinder pressure detection unit is configured. As a result, it is possible to improve workability when integrating the fuel injection device 1 with the fuel injection device 1.

  Further, since the amplification circuit unit 11 is covered with the synthetic resin mold 11a, it is possible to prevent the circuit element from being damaged by heat when the synthetic resin mold 10 is covered and fixed next time. The amplification circuit unit 11 is covered and fixed by the synthetic resin mold 10 on the outside of the metallic large-diameter casing 3 in which the drive circuit (solenoid 24) of the fuel injection device 1 is built, so that it is integrated with the fuel injection device. In this state, the amplifier circuit unit 11 can be easily handled, and the waterproof, heat-insulating, and insulating effects of the amplifier circuit unit 11 can be reliably obtained.

  Connector pins 31 to 33 to which connection lines between the amplifier circuit unit 11 and the control unit 60 are connected are included in the connector portion 51 to which the drive signal line of the fuel injection device 1 is connected, and connector pins 31 to 33 are included. Since the connector pins 21 to 23 are integrally formed as the connector portion 51, the power supply to the amplifier circuit unit 11, the transmission of the pressure detection signal, and the transmission of the fuel injection device drive signal are transmitted through one connector portion. Thus, the assembly work can be facilitated and the fuel injection device 100 with the in-cylinder pressure detection unit can be downsized.

  The failure detection circuit 47 of the amplifier circuit unit 11 has a pull-up resistor RPU, and the ground connection line 61 is not connected to the casing of the fuel injection device 1 in terms of direct current. Since the ECU 60 is connected to the ground via the ECU 60, not only the disconnection or ground fault of the connection lines 62 and 63 but also the disconnection of the ground connection line 61 can be detected by the ECU 60.

  Further, before the cylinder pressure detection unit 101 as a combination of the pressure detection element 2 and the amplification circuit unit 11 is mounted on the engine, sensitivity adjustment is performed in a state where the pressure detection element 2, the charge amplifier 43 and the amplification circuit 45 are combined. Is possible. A pressure detection signal can be obtained by integrating and amplifying the output signal of the pressure detection element 2 by the charge amplifier 43, but it has been confirmed that the detection sensitivity varies due to variations in characteristics of the pressure detection element 2, the charge amplifier 43, and the like. . Therefore, by adjusting the gain of the amplification circuit 45 in a state where the pressure detection element 2 is combined with the charge amplifier 43 and the amplification circuit 45, the influence of the characteristic variation of the pressure detection element 2 and the characteristics of the charge amplifier 43 and the amplification circuit 45 are obtained. It is possible to perform accurate pressure detection by eliminating both the effects of variation.

  In addition, the amplifier circuit unit 11 includes the power supply noise filter 49 for removing noise superimposed on the power supply line that supplies power, and thus reliably prevents noise from being mixed into the pressure detection signal via the power supply line. Can do.

  Further, since the amplifier circuit unit 11 is configured on the flexible printed wiring board, the amplifier circuit unit 11 can be reduced in size and can be easily attached to the fuel injection device 1.

[Modification]
In the above-described embodiment, the amplifier circuit unit 11 is disposed in the vicinity of the connector pins 21 to 23 of the fuel injection device 1, and is integrated with the connector pins 31 to 33 of the amplifier circuit unit 11 to constitute the connector unit 51. However, as shown in FIG. 8, the amplifier circuit unit 11 is disposed at a position away from the main body connector portion 51 a including the connector pins 21 to 23 of the fuel injection device 1, and the connector pins 31 to 33 of the amplifier circuit unit 11 are used. Another 3-pin sub-connector portion 51b may be configured.

  By configuring the connector part 51b separately from the connector part 51a in this way, the connection line 63 for transmitting the pressure detection signal is separated from the drive signal line through which a relatively large current flows, and the drive of the fuel injection device 1 is performed. The influence of the signal on the pressure detection signal can be reduced.

  The synthetic resin molds 10 and 11a may be replaced with ceramic molds, and the large-diameter casing 3 in a state where the amplifier circuit unit 11 is housed in a metal case different from the large-diameter casing 3 of the fuel injection device 1. You may make it fix to the outer side.

  Instead of the power supply noise filter 49, a signal noise filter (low-pass filter) for removing a noise component may be provided between the failure detection circuit 47 and the connector pin 33. Also, the power supply noise filter 49 and the signal noise filter may be provided. May be provided together.

In addition, the sensitivity adjustment circuit 46 of the amplifier circuit unit 11 is configured by a combination of a plurality of resistance elements. However, the present invention is not limited to this. For example, gain adjustment may be performed by writing gain adjustment data in a nonvolatile memory. Good.
The amplifier circuit unit 11 may be configured on a glass epoxy resin substrate, and the connection member 12 may be connected to the glass epoxy resin substrate.

DESCRIPTION OF SYMBOLS 1 Fuel injection apparatus 2 Pressure detection element 10 Synthetic resin mold 11 Amplification circuit unit 11a Synthetic resin mold 21-23 Connector pin 31-33 Connector pin 46 Sensitivity adjustment circuit 47 Fault detection circuit 49 Power supply noise filter 51 Connector part 60 Electronic control unit 100 Fuel Injection Device with In-Cylinder Pressure Detection Unit 101 In-Cylinder Pressure Detection Unit

Claims (8)

An amplifying circuit including a pressure detecting element mounted at a tip of a fuel injection device for injecting fuel into a combustion chamber of an internal combustion engine, and an amplifying circuit for amplifying a signal output from the pressure detecting element and outputting a pressure detecting signal An in-cylinder pressure detecting device for detecting a pressure in the combustion chamber,
A fuel with an in-cylinder pressure detecting unit is integrated with the fuel injection device by integrating the in-cylinder pressure detecting unit including the pressure detecting element, the amplifying circuit unit, and a connecting member for connecting the pressure detecting element and the amplifying circuit unit. Constituting an injection device, mounting the fuel injection device with in-cylinder pressure detection unit on the internal combustion engine ,
The in-cylinder pressure detection unit includes in advance a cylindrical sensor fixing member in which the pressure detection element is fixed to a distal end portion, the amplification circuit unit, and a connection member that connects the pressure detection element and the amplification circuit unit. An in-cylinder pressure detecting device configured by assembling, wherein the sensor fixing member is fitted into a tip portion of the fuel injection device. The amplifier circuit unit is disposed in the vicinity of a connector to which a drive signal line for supplying a drive signal to the fuel injector from a control unit that controls the fuel injector is connected, and the connector includes the amplifier circuit unit and the amplifier circuit unit. The in-cylinder pressure detecting device according to claim 1, wherein the in-cylinder pressure detecting device is configured to include a connection terminal of a connection line between the control unit and the control unit. The fuel injection device includes a main body connector portion including a connection terminal to which a drive signal line that supplies a drive signal from a control unit that controls the fuel injection device is connected.
The in-cylinder pressure detection unit includes a subconnector portion having a connection terminal to which a detection signal line for supplying the pressure detection signal to the control unit is connected, and the subconnector portion is separate from the main body connector portion. The in-cylinder pressure detecting device according to claim 1, wherein the in-cylinder pressure detecting device is configured as follows. The amplification circuit unit is fixed to the outside of a metal casing containing a drive circuit of the fuel injection device in a state of being covered with a molding material or being accommodated in a metal case. cylinder pressure detection device according to any one of 3. The amplification circuit unit includes a failure detection circuit for diagnosing the connection state between the amplification circuit unit and the control unit that supplies the pressure detection signal by the control unit. The in-cylinder pressure detection device according to any one of 4 . The in-cylinder pressure detecting device according to any one of claims 1 to 5 , wherein the amplifier circuit unit includes a sensitivity adjustment circuit for adjusting a gain of the amplifier circuit. The amplifier circuit unit includes any one of claims 1 to 6, characterized in that it comprises a noise filter for removing noise superimposed on the noise and / or the pressure detection signal superimposed on the power supply line for supplying a power supply The in-cylinder pressure detecting device according to item. The in-cylinder pressure detection device according to any one of claims 1 to 7 , wherein the amplification circuit unit is configured on a flexible printed wiring board.

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