JP2008232094A - Control device for glow plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a glow plug capable of performing transmission of a control signal to a heat generating body and transmission of a detection signal of pressure in a cylinder at the time of having an integrated cylinder pressure sensor and reducing its manufacturing costs. <P>SOLUTION: In the control device for a glow plug 10 integrally having the heat generating body 12 and cylinder pressure sensor 13, the control device comprises a first control unit 2 for generating a control signal SC to control the heat generating body 12, a second control unit 20 for controlling the heat generating body 12 on the basis of the generated control signal SC and being input the detected signal from the cylinder pressure sensor 13, and transmission switching means 2a, 2b, 21, and 22 for transmitting the control signal SC from the first control unit to the second control unit and the detected signal from the second control unit to the first control unit at designated transmitting intervals SSCT and SSVT being off each other in response to a combustion cycle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for a glow plug that integrally includes an in-cylinder pressure sensor that detects an in-cylinder pressure generated in a cylinder.

  As a conventional control device for this type of glow plug, for example, a device disclosed in Patent Document 1 is known. This glow plug includes a plug main body having a heating element, and an in-cylinder pressure sensor integrally attached to the plug main body. The in-cylinder pressure sensor outputs a detection signal indicating the in-cylinder pressure generated in the cylinder to the connector. The connector incorporates an IC chip composed of a charge amplifier, an amplifier circuit, etc., and the detection signal from the in-cylinder pressure sensor is output to the IC chip and subjected to predetermined arithmetic processing in various circuits. And output to the ECU via the signal line.

  The heating element is connected to a power source via a connecting bar, and generates heat when electric power is supplied from the power source to assist ignition in the cylinder. Although not disclosed in Patent Document 1, power supply to the heating element is normally controlled by a control signal from the ECU, and this control signal is transmitted from the ECU to the heating element between the ECU and the heating element. A signal line is provided for transmitting to the. As described above, in the conventional glow plug, a signal line for transmitting and receiving a detection signal between the ECU and the in-cylinder pressure sensor and a signal line for transmitting and receiving a control signal between the ECU and the heating element are separately required. As a result, the wiring becomes complicated and the manufacturing cost increases. For the same reason, as the number of ECU terminals to which signal lines are connected increases, the installation space for the terminals increases.

  The present invention has been made to solve such a problem. In the case where the in-cylinder pressure sensor is integrally formed, the transmission of the control signal to the heating element and the transmission of the in-cylinder pressure detection signal are performed in a single manner. An object of the present invention is to provide a control device for a glow plug that can be performed via a signal line, thereby reducing the manufacturing cost.

JP 2001-241372 A

  In order to achieve the above object, the invention according to claim 1 is directed to a heating element 12 for heating the inside of the cylinder 3a of the internal combustion engine 3 and a detection signal (in the embodiment ( Hereinafter, a control device for the glow plug 10 integrally having an in-cylinder pressure sensor 13 for outputting the charge Q), which is the same in this section, and a first control unit for generating a control signal SC for controlling the heating element 12 (ECU 2), a second control unit (GCU 20) that controls the heating element 12 based on the generated control signal SC and receives a detection signal from the in-cylinder pressure sensor 13, a first control unit, and a second control A signal line 8 connected to the unit, and a control signal SC from the first control unit to the second control unit and a detection signal from the second control unit to the first control unit via the signal line 8. Are transmitted in predetermined transmission sections (control signal transmission section SSCT, voltage signal transmission section SSVT) that are shifted from each other according to the combustion cycle (first CAN transceiver 2a, first CAN controller 2b, second CAN transceiver 21, second transmission 2CAN controller 22).

  According to the glow plug control device, the signal line is connected to the first control unit and the second control unit. The first control unit generates a control signal for controlling the heating element that heats the inside of the cylinder, and transmits the control signal to the second control unit via the signal line. Based on this control signal, the second control unit controls the heating element. A detection signal, which is detected by the in-cylinder pressure sensor and represents the in-cylinder pressure generated in the cylinder, is input to the second control unit, and further transmitted from the second control unit to the first control unit via the signal line. The These control signals and detection signals are transmitted between the first control unit and the second control unit by a transmission switching means in a predetermined transmission section shifted from each other according to the combustion cycle.

  The in-cylinder pressure sensor is usually used to detect an in-cylinder pressure generated by combustion in a cylinder of the internal combustion engine. Further, the in-cylinder pressure changes in the crank angle section (hereinafter simply referred to as “section”) from the vicinity of the start of the compression stroke to the end of the expansion stroke during the combustion cycle. Is limited to the section from the start of the compression stroke to the end of the expansion stroke. For this reason, for example, such a section is set as the transmission section of the detection signal of the in-cylinder pressure sensor, and the other sections are set as the transmission section of the control signal, so that the first control unit and the second control unit are set. Thus, it is possible to transmit and receive the control signal and the detection signal without any trouble while obtaining necessary in-cylinder pressure data via a single signal line. As a result, both signals can be transmitted by a single signal line, so that the wiring can be easily performed and the manufacturing cost can be reduced. For the same reason, it is possible to reduce the size of the first control unit by reducing the number of terminals of the first control unit and reducing the installation space of the terminals.

  According to a second aspect of the present invention, in the control device for the glow plug 10 according to the first aspect, the in-cylinder pressure sensor 13 includes a piezoelectric element that outputs a charge Q corresponding to the in-cylinder pressure as a detection signal. The first control unit further includes a charge amplifier 14 having a capacitor 14b for storing the charge Q output from the internal pressure sensor 13 and outputting a signal (voltage signal SV) corresponding to the amount of the charge Q to the second control unit. The discharge timing for discharging the electric charge stored in the capacitor 14b is set, and the reset signal SR including the set discharge timing information is generated and transmitted to the second control unit via the signal line 8 for the second control. The unit controls the discharge of electric charges based on the discharge timing information included in the reset signal SR, and the transmission switching unit transmits the first control unit via the signal line 8. Between the control unit SC and the second control unit, the control signal SC, the detection signal and the reset signal SR are shifted from each other in accordance with the combustion cycle (control signal transmission section SSCT, voltage signal transmission section SSVT, reset signal transmission section). (SSRT).

  According to this configuration, the in-cylinder pressure sensor has the piezoelectric element, and an amount of electric charge corresponding to the in-cylinder pressure generated in the piezoelectric element is output as the detection signal and stored in the capacitor of the charge amplifier. The charge amplifier outputs a signal corresponding to the amount of stored charge to the second control unit, and this signal is transmitted from the second control unit to the first control unit. The first control unit sets a timing for discharging the charge stored in the capacitor, generates a reset signal including the set discharge timing information, and transmits the reset signal to the second control unit via the signal line. The second control unit controls the discharge of the electric charge stored in the capacitor based on the discharge timing information included in the reset signal. This discharge is performed to avoid a decrease in the detection accuracy of the in-cylinder pressure due to the detection signal of the in-cylinder pressure sensor drifting with respect to the actual in-cylinder pressure because the piezoelectric element has pyroelectricity. .

  According to the present invention, the reset signal including the discharge timing information is also transmitted in a predetermined transmission section shifted from each other according to the combustion cycle together with the control signal and the detection signal described above. For this reason, for example, by setting the transmission interval of the reset signal to a predetermined interval within the transmission interval of the control signal, the reset signal is added between the first control unit and the second control unit in addition to the control signal and the detection signal. Can be transmitted by a single signal line.

  According to a third aspect of the present invention, in the control device for the glow plug 10 according to the second aspect, the operation state detecting means (crank angle sensor 31) for detecting the operation state (engine speed NE) of the internal combustion engine 3 is further provided. The first control unit sets the discharge timing of the capacitor 14b according to the detected operating state of the internal combustion engine 3.

  The time interval between combustion cycles varies depending on the operating state of the internal combustion engine. According to the present invention, since the discharge timing of the capacitor is set according to the operating state of the internal combustion engine, the electric charge can be discharged at an appropriate timing according to the change in the time interval between the combustion cycles. As a result, drift of the detection signal of the in-cylinder pressure sensor can be appropriately avoided, and the detection accuracy of the in-cylinder pressure can be increased.

  According to a fourth aspect of the present invention, in the control device for the glow plug 10 according to the second or third aspect, the failure determination means (failure determination circuit 24, FIG. 7) that determines the failure of the second control unit according to the detection signal. Steps 6 to 8) are further provided.

  According to this configuration, the failure of the second control unit is determined according to the detection signal from the in-cylinder pressure sensor. Since the piezoelectric element has pyroelectricity, a failure has occurred in the second control unit that controls the heating element. For example, when the heating element is always generating heat, the piezoelectric element is heated. The detection signal of the in-cylinder pressure sensor greatly changes (drifts) immediately after the electric charge is discharged. Therefore, the failure of the second control unit can be appropriately determined according to the detection signal of the in-cylinder pressure sensor.

  According to a fifth aspect of the present invention, in the glow plug 10 control device according to any one of the first to fourth aspects, the second control unit is built in the glow plug 10.

  According to this configuration, a space around the glow plug can be secured by incorporating the second control unit in the glow plug. In addition, the distance between the second control unit and the in-cylinder pressure sensor can be shortened, and noise can be prevented from being mixed into the detection signal. As a result, the in-cylinder pressure detection accuracy can be further increased.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of a control device according to an embodiment of the present invention and an internal combustion engine (hereinafter referred to as “engine”) 3 to which the control device is applied. The engine 3 is, for example, an in-line four-cylinder diesel engine having four cylinders 3a (only one is shown), and is mounted on a vehicle (not shown). A combustion chamber 3e is formed between the piston 3b and the cylinder head 3c of each cylinder 3a.

  An intake pipe 4 and an exhaust pipe 5 are connected to the cylinder head 3c, and a fuel injection valve (hereinafter referred to as “injector”) 6 and a glow plug 10 are attached so as to face the combustion chamber 3e. The fuel injection amount and fuel injection timing of the injector 6 are controlled by an ECU 2 (first control unit) described later.

  2 and 3, the glow plug 10 includes a case 11, a heating element 12, an in-cylinder pressure sensor 13, a charge amplifier 14, a coupler 15 attached to the upper end of the case 11, and a control dedicated to the glow plug 10. A unit (hereinafter referred to as “GCU”) 20 (second control unit) is provided.

  The heating element 12 is made of, for example, a ceramic with a built-in heating wire and is formed in a rod shape. The upper half of the heating element 12 is accommodated in the case 11. The heating element 12 is connected to a battery (both not shown) via electrodes, and generates heat by the electric power supplied from the battery to heat the inside of the cylinder 3a. The supply timing and supply time of power to the heating element 12 are controlled by a heating element control signal SCH described later from the GCU 20.

  The in-cylinder pressure sensor 13 is composed of an annular piezoelectric element having a predetermined thickness, and is housed in the case 11 while being passed through the heating element 12. In general, when an external force is applied to a piezoelectric element, the magnitude of polarization changes according to the magnitude of the external force. Therefore, the in-cylinder pressure sensor 13 generates an amount of electric charge Q corresponding to the in-cylinder pressure and outputs it to the charge amplifier 14.

  The charge amplifier 14 is accommodated in the case 11 and includes an operational amplifier 14a and a capacitor 14b as shown in FIG. The operational amplifier 14a has an inverting input terminal connected to the in-cylinder pressure sensor 13 and a non-inverting input terminal connected to the ground. The capacitor 14b is connected in parallel to the inverting input terminal and the output terminal of the operational amplifier 14a. With such a configuration, the charge Q output from the in-cylinder pressure sensor 13 is stored in the capacitor 14b, and a voltage signal SV proportional to the stored charge amount is output from the operational amplifier 14a to the second CAN controller 22 described later of the GCU 20. Is done. Further, the electric charge stored in the capacitor 14b is discharged in response to a charge reset signal SRC described later from the GCU 20.

  A filter 7 is provided in the exhaust pipe 5 of the engine 3. This filter 7 reduces the amount of PM discharged into the atmosphere by collecting particulates (hereinafter referred to as “PM”) such as soot in the exhaust gas. Further, the filter 7 carries an oxidation catalyst (not shown) on its surface, and the temperature of the filter 7 is increased by the oxidation reaction of the oxidation catalyst, whereby PM is burned and the filter 7 is regenerated. The regeneration operation of the filter 7 is controlled by the ECU 2, and is performed by additionally injecting fuel into the combustion chamber 3e and causing the heating element 12 to generate heat.

  A crank angle sensor 31 is provided on the crankshaft 3d of the engine 3 (see FIG. 3). The crank angle sensor 31 (operating state detection means) outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3d rotates.

  The CRK signal is output every predetermined crank angle (for example, 1 °). The ECU 2 obtains the rotational speed NE (hereinafter referred to as “engine rotational speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3b is at a predetermined crank angle position near the TDC (top dead center) at the start of the intake stroke.

  The ECU 2 includes a CPU, a RAM, a ROM (all not shown), a first CAN transceiver 2a, a first CAN controller 2b, and the like. The detection signals from the crank angle sensor 31 and the detection signals from various sensors (not shown) are output to the CPU.

  In accordance with these detection signals, the CPU executes engine control including fuel injection control in accordance with a control program stored in the ROM. The CPU sets the supply timing and supply time of the power to the heating element 12 according to the engine speed NE when starting the engine 3 or during the regeneration of the filter 7, and sets these supply timing and supply. A pulse signal including time information is generated as a control signal SC and output to the first CAN controller 2b.

  Further, the CPU sets the timing for discharging the electric charge of the capacitor 14b based on the engine speed NE, generates a pulse signal including the set discharge timing information as the reset signal SR, and outputs it to the first CAN controller 2b. .

  Further, the CPU calculates the current crank angle CA based on the CRK signal and the TDC signal, and outputs it to the first CAN controller 2b. The crank angle CA is reset to a value of 0 when the TDC signal is generated, and is incremented every time a CRK signal output every 1 ° is generated. Therefore, the crank angle CA is 0 ° at the TDC position at the start of the intake stroke, 180 ° at the BDC position at the start of the compression stroke, 360 ° at the TDC position at the start of the expansion stroke, and 540 ° at the BDC position at the start of the exhaust stroke. (See FIG. 6).

  The first CAN transceiver 2a (transmission switching means) is for performing transmission of the control signal SC and reset signal SR and reception of the voltage signal SV with the GCU 20 via the signal line 8 by CAN communication. It is.

  The first CAN controller 2b (transmission switching means) controls signal transmission / reception by the first CAN transceiver 2a based on the crank angle CA. Specifically, as shown in FIG. 6, the first CAN controller 2b sends the reset signal SR to the first CAN transceiver 2a in the SSRT from the start to the end of the intake stroke (hereinafter referred to as “reset signal transmission section”). The reset signal SR is transmitted to the GCU 20 from the first CAN transceiver 2a via the signal line 8 (see FIG. 3). Similarly, the first CAN controller 2b outputs a control signal SC to the first CAN transceiver 2a in an interval (hereinafter referred to as “control signal transmission interval”) SSCT from the start to the end of the exhaust stroke. The first CAN transceiver 2a transmits the signal to the GCU 20 via the signal line 8 (see FIG. 3).

  In addition, the first CAN controller 2b sends a signal permitting reception of the voltage signal SV to the first CAN transceiver 2a in the SSVT from the start of the compression stroke to the end of the expansion stroke (hereinafter referred to as “voltage signal transmission interval”). In response, the first CAN transceiver 2a receives the voltage signal SV from the GCU 20 via the signal line 8, and outputs the received voltage signal SV to the first CAN controller 2b (see FIG. 3). The first CAN controller 2b outputs this voltage signal SV to the CPU. Further, the first CAN controller 2 b outputs the crank angle CA to the second CAN controller 22 described later of the GCU 20 via the second signal line 9.

  The GCU 20 is built in the coupler 15 and includes a second CAN transceiver 21, a second CAN controller 22, a heating element control circuit 23, a failure determination circuit 24, a cutoff circuit 25, a reset circuit 26, and the like as shown in FIG. ing.

  The second CAN transceiver 21 (transmission switching means) is for performing transmission / reception of the control signal SC, the reset signal SR and the voltage signal SV with the ECU 2 via the signal line 8 by CAN communication.

  The second CAN controller 22 (transmission switching means) controls transmission / reception of signals by the second CAN transceiver 21 based on the crank angle CA input from the first CAN controller 2b. Specifically, the second CAN controller 22 outputs the voltage signal SV to the second CAN transceiver 21 in the voltage signal transmission section SSVT, and the voltage signal SV is sent from the second CAN transceiver 21 to the ECU 2 via the signal line 8. Sent.

  Further, the second CAN controller 22 outputs a signal permitting reception of the reset signal SR and the control signal SC from the ECU 2 to the second CAN transceiver 21 in the reset signal transmission section SSRT and the control signal transmission section SSCT, and accordingly, The second CAN transceiver 21 receives these signals and outputs them to the second CAN controller 22. Further, the second CAN controller 22 generates a heating element control signal SCH for controlling the heating element 12 based on the information on the power supply timing and the supply time included in the input control signal SC.

  Specifically, by searching a map (not shown) based on the fall timing and fall period of the control signal SC as shown in FIG. 6, the supply timing and supply time of the power to the heating element 12 are determined. Set. Then, a pulse signal having a duty ratio corresponding to the set supply timing and supply time is generated as the heating element control signal SCH and output to the heating element control circuit 23.

  The heating element control circuit 23 is composed of, for example, an npn-junction bipolar transistor, and its collector, emitter, and base are connected to a battery (not shown), the heating element 12, and the second CAN controller 22 via a cutoff circuit 25, respectively. It is connected to the. The heating element control circuit 23 is turned on / off in response to the heating element control signal SCH from the second CAN controller 22. Thereby, supply and stop of electric power to the heating element 12 are controlled, and the temperature of the heating element 12 is controlled according to the duty ratio of the heating element control signal SCH.

  The failure determination circuit 24 (failure determination means) receives the crank angle CA from the second CAN controller 22 and the voltage signal SV from the charge amplifier 14. The failure determination circuit 24 uses the voltage signal SV to generate the heating element 12. The failure of the heating element control system including the heating element control circuit 23 of the GCU 20 that controls the control is determined.

  FIG. 7 is a flowchart showing a failure determination process of the heating element control system. This process is executed in synchronization with the generation of the CRK signal. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the heat generation control of the heating element 12 is being performed. When this determination result is YES, this processing is ended as it is.

  On the other hand, when the determination result in step 1 is NO, it is determined whether or not the crank angle CA is equal to a first predetermined angle CAREF1 (for example, 180 °) near the start of the compression stroke (step 2). When the determination result is YES, the voltage value of the voltage signal SV at that time is set as the first voltage value V1 (step 3), and then this process is terminated. On the other hand, when the determination result in step 2 is NO, it is determined whether or not the crank angle CA is equal to a second predetermined angle CAREF2 (for example, 540 °) near the end of the expansion stroke (step 4). If the determination result is NO, the present process is terminated, while if YES, the voltage value of the voltage signal SV at that time is set as the second voltage value V2 (step 5).

  Next, the ratio (V1 / V2) between the first voltage value V1 and the second voltage value V2 set as described above is set to a first predetermined value VREFL (for example, 0.9) and a second predetermined value VREFH (for example, It is determined whether or not it is within the predetermined range defined in 1.1) (step 6). When the determination result is YES, assuming that the heating element control system including the heating element control circuit 23 of the GCU 20 is normal, the failure flag F_CHNG is set to “0” (step 7), and then this process is terminated.

  On the other hand, when the determination result of step 6 is NO and the V1 / V2 value is out of the above predetermined range, power is always supplied to the heating element 12, and the ON failure such that the heating element 12 generates heat. Is generated in the heating element control system, the failure flag F_CHNG is set to “1” to indicate this (step 8), and this process is terminated. Since the piezoelectric element has pyroelectricity, when the heating element control system is in an ON failure, the heating element 12 always generates heat, and the piezoelectric element is heated, so that the voltage signal SV drifts greatly. Since the in-cylinder pressure is substantially the same at the start of the compression stroke and at the end of the expansion stroke, the first voltage value V1 at the first predetermined angle CAREF1 is obtained if the heating element control system is not on-failed. The second voltage value V2 at the second predetermined angle CAREF2 is substantially the same. Therefore, when the ratio between the detected first voltage value V1 and the second voltage value V2 is out of the predetermined range, it can be appropriately determined that the heating element control system has an ON failure. Further, the failure determination circuit 24 outputs a failure signal SF to the cutoff circuit 25 when the heating element control system has an ON failure.

  The shut-off circuit 25 is configured by, for example, a normally closed relay, and is connected between the collector of the heating element control circuit 23 and the battery. When the failure signal SF is input from the failure determination circuit 24, the interruption circuit 25 generates heat. By opening the body control circuit 23, the supply of electric power to the heating element 12 is stopped.

  Further, the second CAN controller 22 generates a charge reset signal SRC for controlling the discharge timing of the capacitor 14b based on the discharge timing information included in the reset signal SR received from the ECU 2.

  Specifically, the discharge timing of the capacitor 14b is set to the searched timing during the intake stroke by searching a map (not shown) based on the falling timing of the reset signal SR as shown in FIG. To do. Then, a charge reset signal SRC corresponding to the set discharge timing is generated and output to the reset circuit 26.

  The reset circuit 26 is composed of, for example, an npn-junction bipolar transistor. As shown in FIG. 4, the collector, the emitter, and the base are connected to the capacitor 14b, the ground, and the second CAN controller 22, respectively. When the charge reset signal SRC from the second CAN controller 22 is input, the reset circuit 26 makes the collector-emitter conductive. Thereby, the electric charge stored in the capacitor 14b is discharged. This discharge avoids a decrease in the detection accuracy of the in-cylinder pressure due to the drift of the voltage signal SV of the in-cylinder pressure sensor 13 with respect to the actual in-cylinder pressure because the piezoelectric element of the in-cylinder pressure sensor 13 has pyroelectricity. Is to be done.

  As described above, according to the present embodiment, as shown in FIG. 6, the reset signal SR is transmitted from the ECU 2 to the GCU 20 via the signal line 8 in the reset signal transmission section SSRT corresponding to the intake stroke. Subsequently, the voltage signal SV is transmitted from the GCU 20 to the ECU 2 via the signal line 8 in the voltage signal transmission section SSVT corresponding to the section from the start of the compression stroke to the end of the expansion stroke. Further subsequently, the control signal SC is transmitted from the ECU 2 to the GCU 20 via the signal line 8 in the control signal transmission section SSCT corresponding to the exhaust stroke.

  Therefore, transmission / reception of the reset signal SR, the voltage signal SV, and the control signal SC can be performed between the ECU 2 and the GCU 20 through the single signal line 8 without any trouble, thereby reducing the manufacturing cost. Can do. For the same reason, the number of terminals of the ECU 2 can be reduced, and the ECU 2 can be downsized.

  In addition, since the voltage signal transmission section SSVT is set in a section from the start of the compression stroke to the end of the expansion stroke, the in-cylinder pressure can be detected without any trouble while obtaining necessary in-cylinder pressure data. .

  Furthermore, since the discharge timing of the capacitor 14b is set according to the engine speed NE, the electric charge can be discharged at an appropriate timing according to the change in the time interval between the combustion cycles, and the drift of the voltage signal SV can be appropriately avoided. In addition, the detection accuracy of the in-cylinder pressure can be increased.

  Further, since the GCU 20 is built in the coupler 15, a space around the glow plug 10 can be secured. Further, since the distance between the in-cylinder pressure sensor 13 and the GCU 20 can be shortened and noise can be prevented from being mixed into the voltage signal SV, the in-cylinder pressure detection accuracy can be further increased.

  Further, the failure determination process of FIG. 7 can appropriately determine the ON failure of the heating element control system including the heating element control circuit 23 of the GCU 20 according to the voltage signal SV from the in-cylinder pressure sensor 13. Further, when it is determined that the heating element control system has an ON failure, the power supply to the heating element 12 is stopped by the cutoff circuit 25, so that the engine 3 can be prevented from being overheated, thereby improving the exhaust gas characteristics. be able to.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, the control signal transmission section SSCT is set to the exhaust stroke. However, the present invention is not limited to this, and any section other than the voltage signal transmission section SSVT can be set. The same applies to the reset signal transmission section SSRT. Further, when the number of signals transmitted and received between the ECU 2 and the GCU 20 increases, the transmission section other than the voltage signal transmission section SSVT is subdivided, so that a single signal line 8 is passed between the ECU 2 and the GCU 20. Can transmit and receive signals. Furthermore, although the GCU 20 is built in the glow plug 10 in the embodiment, it may be provided outside the glow plug 10. In the embodiment, the heating element control circuit 23 is configured by a transistor, but is not limited thereto, and may be configured by, for example, a relay.

  Furthermore, the present invention is not limited to the engine of the embodiment mounted on a vehicle, but can be applied to an engine for a marine propulsion device such as an outboard motor in which a crankshaft is arranged vertically. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

It is a figure which shows schematic structure of the internal combustion engine to which the control apparatus of this invention is applied. It is an enlarged view of a glow plug. It is a block diagram which shows a control apparatus roughly. It is a circuit diagram of a charge amplifier. FIG. 4 is a block diagram schematically showing the GCU of FIG. 3. It is a figure which shows an example of the transmission area of a reset signal, a voltage signal, and a control signal. It is a flowchart which shows the failure determination process of the heat generating body control system of GCU.

Explanation of symbols

2 ECU (first control unit)
2a First CAN transceiver (transmission switching means)
2b First CAN controller (transmission switching means)
3 Engine 3a Cylinder 8 Signal line 10 Glow plug 12 Heating element 13 In-cylinder pressure sensor 14b Capacitor 20 GCU (second control unit)
21 2nd CAN transceiver (transmission switching means)
22 Second CAN controller (transmission switching means)
24 Failure determination circuit (failure determination means)
31 Crank angle sensor (operating state detection means)
Q charge (detection signal)
SC control signal SV voltage signal (signal according to the amount of charge)
SR reset signal SSCT control signal transmission section (predetermined transmission section)
SSVT Voltage signal transmission section (predetermined transmission section)
SSRT reset signal transmission section (predetermined transmission section)
NE engine speed (operating condition of internal combustion engine)

Claims (5)

A glow plug control device integrally having a heating element for heating the inside of a cylinder of an internal combustion engine and an in-cylinder pressure sensor for outputting a detection signal representing an in-cylinder pressure generated in the cylinder,
A first control unit that generates a control signal for controlling the heating element;
A second control unit that controls the heating element based on the generated control signal and receives the detection signal from the in-cylinder pressure sensor;
A signal line connected to the first control unit and the second control unit;
The control signal from the first control unit to the second control unit and the detection signal from the second control unit to the first control unit are shifted from each other according to the combustion cycle via the signal line. Transmission switching means for transmitting in a predetermined transmission section;
A control device for a glow plug, comprising: The in-cylinder pressure sensor has a piezoelectric element that outputs an amount of charge corresponding to the in-cylinder pressure as the detection signal,
A capacitor that stores the charge output from the in-cylinder pressure sensor, and further includes a charge amplifier that outputs a signal corresponding to the amount of the charge to the second control unit;
The first control unit sets a discharge timing for discharging the electric charge stored in the capacitor, generates a reset signal including the set discharge timing information, and the second control unit via the signal line To
The second control unit controls the discharge of the charge based on the discharge timing information included in the reset signal,
The transmission switching means is configured such that the control signal, the detection signal, and the reset signal are deviated from each other according to a combustion cycle between the first control unit and the second control unit via the signal line. The glow plug control device according to claim 1, wherein the transmission is performed in a transmission section. An operation state detecting means for detecting an operation state of the internal combustion engine;
The glow plug control device according to claim 2, wherein the first control unit sets the discharge timing of the capacitor in accordance with the detected operating state of the internal combustion engine.   4. The glow plug control device according to claim 2, further comprising a failure determination unit that determines a failure of the second control unit according to the detection signal. 5.   5. The glow plug control device according to claim 1, wherein the second control unit is built in the glow plug. 6.

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