JP2009019778A - Temperature control system of heating element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature control system capable of reducing costs and suppressing temperature error of a heating element. <P>SOLUTION: ECU (electric control unit) 40 opens and closes a power supply passage from a battery 21 to a glow plug 20 by GDU (glow plug driving unit) 30. More concretely, ECU 40 opens and closes GDU 30 by an opening/closing control signal. Here, a temperature of the glow plug 20 is controlled by duty of the opening/closing control signal. In temperature control of the glow plug 20, GDU 30 superposes battery voltage (plug driving voltage) input through a harness 22 to a diagnostic signal. Further, ECU 40 outputs the opening/closing signal of the duty according to the plug driving voltage superposed to the diagnostic signal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a temperature control system for controlling power supplied to a heating element in order to control the temperature of the heating element provided in a combustion chamber of an internal combustion engine.

  Conventionally, a temperature control system for controlling the temperature of a glow plug as a heating element provided in a combustion chamber of a diesel engine to a target temperature is well known. In this type of temperature control system, the power supplied to the glow plug is controlled by intermittently energizing the glow plug from the battery, thereby controlling the temperature of the plug (for example, refer to Patent Document 1). In this case, the power supplied to the glow plug (the temperature of the glow plug) is set by the energization amount to the glow plug and the voltage of the power supply path from the battery to the glow plug.

Therefore, in this type of temperature control system, the glow plug temperature error (glow plug target caused by a change in battery voltage) is controlled by controlling the energization amount to the glow plug in consideration of the voltage of the power supply path. Some have been proposed that suppress the difference between the actual temperature and the temperature. For example, an electronic control device (hereinafter referred to as “ECU”) that controls each part of an engine system mainly composed of a diesel engine acquires a battery voltage (ECU power supply voltage) supplied as power to the ECU, Some control the amount of current supplied to the glow plug based on this. In addition, there are some which have dedicated hardware for acquiring the voltage of the power supply path to the glow plug and controlling the energization amount to the plug based on the voltage.
JP 2006-132869 A

  However, in the temperature control system that controls the energization amount to the glow plug based on the power supply voltage of the ECU, a temperature error of the glow plug occurs when the power supply voltage of the ECU and the voltage of the power supply path are different. In particular, it is conceivable that the power consumption of the glow plug is considerably larger than the power consumption of the ECU. In this case, if the electrical resistance of the glow plug or the cable constituting the power supply path changes due to aging, the voltage change of the power supply path increases, so the voltage of the power supply path is estimated from the power supply voltage of the ECU. It is not easy to do. That is, there is a possibility that the temperature error of the glow plug may increase due to the electrical resistance of the cable changing with aging. Moreover, in a temperature control system provided with dedicated hardware, there is a concern about an increase in cost due to an increase in the number of parts.

  The present invention has been made in order to solve the above-described problems, and has as its main object to provide a temperature control system that can reduce the temperature error of the heating element at low cost.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  According to the first aspect of the present invention, the heating element provided in the combustion chamber of the internal combustion engine generates heat according to the supplied power, the power supply for supplying power to the heating element, and the power supply path from the power supply to the heating element. A heating element driving device that interrupts energization to the heating element through the same power supply path, and a control device that interrupts energization to the heating element by the heating element driving device to control the power supplied to the heating element. Prepare. According to this configuration, the power supply to the heating element is intermittently controlled by the control of the control device, the power supplied to the heating element is controlled, and consequently the temperature of the heating element is controlled.

  Further, the control device acquires the voltage of the power supply path to the heating element, and controls the heating element driving device based on the acquired voltage. That is, the energization amount to the heating element is increased or decreased based on the voltage of the power supply path to the heating element. Thereby, the power supplied to the heating element can be accurately controlled to the power corresponding to the target temperature, and the temperature error of the heating element can be suppressed. Further, since it is not necessary to provide the heating element driving device with dedicated hardware for controlling the amount of power supplied to the heating element based on the voltage of the power supply path to the heating element, the number of parts is reduced and the cost is reduced. be able to.

  In a second aspect of the present invention, the heating element driving device has an output circuit that outputs an electrical signal to the control device. The output circuit superimposes the voltage of the power supply path on the electric signal, and the control device controls the heating element driving device based on the voltage of the power supply path superimposed on the electric signal by the output circuit. When there is an electrical signal transmitted from the heating element driving device to the control device in this way, new hardware (for example, to the heating element) is created by superimposing the voltage of the power supply path on the existing electrical signal. The temperature error of the heating element can be suppressed without adding a cable for transmitting the voltage of the power supply path from the heating element driving device to the control device and a connector for connecting the cable.

  For example, as a method of superimposing the voltage of the power supply path to the heating element on the electric signal, when the electric signal indicates a bit string, the signal level at the time of the high level of the electric signal indicates the voltage of the power supply path. (Claim 3). Specifically, when the heating element driving device includes a determination circuit that determines whether there is an abnormality in the device and the output circuit includes a bit indicating the presence / absence (determination result) of the abnormality in the bit string, The signal level when the signal is at a high level may indicate the voltage of the power supply path (claim 4).

  In this case, it is considered that the determination result is more normal than abnormal. Therefore, when the voltage of the power supply path is superimposed on the electric signal indicating the determination result, the corresponding bit of the bit string is set to the high level when the determination result indicates normality, and the determination result indicates an abnormality. In this case, it is desirable to set the corresponding bit of the bit string to a low level. Thereby, the period when the voltage of the power supply path to the heating element is superimposed on the electric signal can be lengthened.

  Further, it is desirable that a bit string whose signal level at the high level indicates the voltage of the same power supply path includes a bit that always indicates the high level. Thereby, the voltage of the power supply path from the electric signal to the heating element can be reliably acquired in the control device.

  As an output circuit that outputs a bit string whose signal level at the high level indicates the voltage of the same power supply path, the following circuit can be considered. That is, a signal line for transmitting an electric signal is connected to the power supply path, and the output circuit has a switching element that opens and closes the connection between the signal line and the ground. Then, the bit of the bit string is set to a high level by opening the connection between the signal line and the ground by the switching element, and the bit of the bit string is set to the low level by closing the signal line and the ground by the switching element. 7).

  In the invention according to claim 8, when the control device acquires the voltage of the power supply path each time, if the voltage of the power supply path to the heating element is not superimposed on the electric signal, it is acquired last time. Let the voltage of the power supply path be the voltage of the current power supply path. Thus, by complementing the voltage of the power supply path to the heating element, even if the voltage of the power supply path is not superimposed on the electrical signal, it is based on the complemented voltage of the power supply path. The temperature of the heating element can be controlled.

  In the invention according to claim 9, the power source is a secondary battery. Since the output voltage of the secondary battery varies greatly depending on the discharge amount or the charge amount, it is considered that the effect of the present invention is great.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the present embodiment, the present invention is embodied as an engine system mainly composed of a diesel engine, and the detailed configuration thereof will be described below. First, the overall configuration of the engine system according to the present embodiment will be described with reference to FIG.

  The intake passage 11 of the diesel engine 10 shown in FIG. 1 communicates with a combustion chamber 15 defined by a cylinder block 13 and a piston 14 by opening an intake valve 12. In the combustion chamber 15, a tip end portion of the fuel injection valve 16 protrudes so that fuel can be injected into the combustion chamber 15. When the fuel injected into the combustion chamber 15 by the fuel injection valve 16 is compressed in the combustion chamber 15, the fuel self-ignites to generate energy. This energy is taken out as rotational energy of the output shaft (crankshaft) 17 of the diesel engine 10 via the piston 14. On the other hand, the gas used for combustion is discharged into the exhaust passage 19 by opening the exhaust valve 18.

  Further, the tip of a glow plug 20 as a heat generating means is disposed in the combustion chamber 15 so as to protrude. A glow plug drive unit (hereinafter referred to as “GDU”) 30 is connected to the glow plug 20 via a harness 23, and a battery 21 is connected to the GDU 30 via a harness 22. The GDU 30 intermittently energizes the glow plug 20. The power supply path includes harnesses 22 and 23.

  A crank angle sensor 24 for detecting the rotation angle of the crankshaft 17 is provided in the vicinity of the crankshaft 17, and a water temperature sensor 25 for detecting the temperature of the cooling water of the diesel engine 10 is provided in the cylinder block 13. . The fuel injection valve 16, the crank angle sensor 24, the water temperature sensor 25, and the GDU 30 are connected to the ECU 40.

  The ECU 40 is connected to the battery 21 via the harness 26 and receives power supply from the battery 21. The ECU 40 is an electronic control unit mainly composed of a well-known microcomputer equipped with a CPU, a memory, etc., the memory stores various programs and parameters, and the CPU executes a program stored in the memory to execute a diesel engine. 10 parts are controlled.

  Next, the configuration of the GDU 30 will be described with reference to FIG. In FIG. 2, the configuration other than the GDU 30 is indicated by a one-dot chain line. The GDU 30 includes an amplification circuit 31 that inverts and amplifies the energization control signal, a switch unit 32 that opens and closes a power supply path from the battery 21 to the glow plug 20, and an abnormality detection unit 33 that determines whether there is an abnormality in the switch unit. I have.

  Specifically, the amplifier circuit 31 is connected to the input terminal T1 to which the energization control signal of the ECU 40 is input, and the control electrode of the power transistor TR1 constituting the switch unit 32 is connected to the amplifier circuit 31. The power transistor TR1 is provided between the power supply terminal T2 and the plug connection terminal T3. Here, the power supply terminal T2 is a terminal for connecting the battery 21 via the harness 22, and the plug connection terminal T3 is a terminal for connecting the glow plug 20 via the harness 23. Thus, when a low-level energization control signal is input, the power transistor TR1 is turned on so that the glow plug 20 is energized. On the other hand, when a high-level energization control signal is input, the power transistor TR1 is turned off, whereby the energization to the glow plug 20 is stopped.

  The abnormality detection unit 33 acquires various types of information such as the voltage at the plug connection terminal T3 and the current flowing through the power transistor TR1 from the switch unit 32, and determines whether there is an abnormality in the switch unit 32 and the glow plug 20 based on the information. The determination result is output to the output terminal T4 as a diagnosis signal. The abnormality detection unit 33 is supplied with power from the battery 21 via the harness 26 and the power supply terminal T5.

  Here, the diagnosis signal will be described in detail. The signal is an asynchronous signal including a start bit, a plurality of information bits, and a stop bit as shown in FIG. FIG. 3 illustrates a 24-bit diagnostic signal.

  The start bit is a bit that always indicates a low level and indicates the start of transmission of an information bit. The plurality of information bits respectively correspond to determination results relating to a plurality of determination items. A high-level information bit indicates that the determination result of the corresponding determination item is normal, and a low-level information bit indicates that the determination result of the corresponding determination item is abnormal. On the other hand, the stop bit is a bit that always indicates a high level, and is continuously transmitted from the end of transmission of the information bit until the next start bit is transmitted.

  According to the engine system, the duty control of the temperature of the glow plug 20 is performed in order to improve the ignitability of fuel when the diesel engine 10 is cold-started. That is, the ECU 40 outputs an energization control signal with a duty corresponding to the target temperature of the glow plug 20, and the GDU 30 intermittently energizes the glow plug 20 according to the energization control signal. As a result, the energization amount to the glow plug 20 is controlled, the power supplied to the glow plug 20 is controlled, and consequently the temperature of the glow plug 20 is controlled.

  However, in reality, the power supplied to the glow plug 20 changes according to the voltage of the power supply path from the battery 21 to the glow plug 20. Therefore, in this embodiment, the ECU 40 controls the duty of the energization control signal based on a voltage (hereinafter referred to as “plug drive voltage”) applied to the power supply terminal T2 of the GDU 30 via the harness 22. .

  By the way, as such control, a plug drive voltage is estimated from a battery voltage (hereinafter referred to as “power supply voltage of the ECU 40”) applied to the ECU 40 via the harness 26 of the ECU 40, and based on the estimated plug drive voltage. It is conceivable to control the duty of the energization control signal. However, in this control, a temperature error of the glow plug 20 occurs when the estimated plug drive voltage and the actual plug drive voltage are different. In particular, it is conceivable that the power consumption of the glow plug 20 is considerably larger than the power consumption of the ECU 40. In this case, if the electrical resistance of the glow plug 20 or the harness 22 changes with the passage of time, the change in the plug drive voltage becomes large. Therefore, it is not easy to estimate the plug drive voltage from the power supply voltage of the ECU 40. As a result, the temperature error of the glow plug 20 may increase due to changes in the electrical resistance of the glow plug 20 and the harness 22 over time.

  Therefore, in the present embodiment, the ECU 40 controls the duty of the energization control signal based on the voltage of the power supply path to the glow plug 20. Thereby, the temperature error of the glow plug 20 resulting from the change of the electrical resistance of the glow plug 20 or the harness 22 can be suppressed.

  Further, the GDU 30 superimposes the plug drive voltage on the existing electrical signal (diag signal), and the ECU 40 controls the duty of the energization control signal based on the plug drive voltage superimposed on the electrical signal. Thereby, it is not necessary to add new hardware (for example, a harness for transmitting the plug drive voltage from the GDU 30 to the ECU 40 or a connector for connecting the harness).

  Specifically, as shown in FIG. 4, the abnormality detection unit 33 of the GDU 30 includes a determination circuit 34 that outputs a determination signal indicating whether or not there is an abnormality in the switch unit 32, and a transistor TR2 that is turned on or off according to the determination signal. And an output circuit 35 mainly composed of In this output circuit 35, a signal line 36 for transmitting a diagnostic signal is connected to a power supply path to the glow plug 20 via a power supply terminal T2 (see FIG. 2), and between the signal line 36 and the ground. A transistor TR2 is provided. According to the output circuit 35, when the transistor TR2 is in the off state (high level), the signal level indicates the plug drive voltage, and when the transistor TR2 is in the on state, the signal level is higher than that at the high level. Also shows a low voltage.

  Next, a process for calculating the duty of the energization control signal (hereinafter referred to as “duty calculation process”) will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of the duty calculation program. This program is executed by the ECU 40 at a predetermined cycle (every predetermined crank angle or at a predetermined time cycle).

  First, in step S10, the ECU 40 determines whether or not the signal level of the energization control signal is equal to or less than the first threshold value TH1. When the ECU 40 determines that the signal level of the energization control signal is equal to or less than the first threshold value TH1, the ECU 40 proceeds to the subsequent step S11 and determines that the signal level of the energization control signal is greater than the first threshold value TH1. Then, the current duty calculation process is terminated.

  In step S11, the ECU 40 samples the diagnosis signal. That is, the ECU 40 stores the voltage of the diagnostic signal at that time as a sample value in a memory or the like.

  In step S12, the ECU 40 determines whether or not the sample value of the diagnosis signal is greater than or equal to the second threshold value TH2. When the ECU 40 determines that the sample value of the diagnosis signal is greater than or equal to the second threshold TH2, the ECU 40 determines that the bit value of the bit string indicated by the diagnosis signal is “1” (see step S13). On the other hand, when the ECU 40 determines that the sample value of the diagnosis signal is smaller than the second threshold value TH2, the ECU 40 determines that the bit value of the bit string indicated by the diagnosis signal is “0” (see step S14).

  In step S15, the ECU 40 determines whether or not the sample value of the diagnosis signal is greater than or equal to the third threshold value TH3. When the ECU 40 determines that the sample value of the diagnosis signal is greater than or equal to the third threshold value TH3, the ECU 40 uses the sample value of the diagnosis signal as an estimated value of the current plug drive voltage (hereinafter referred to as “estimated plug drive voltage”) VG (i ) (See step S16). On the other hand, when the ECU 40 determines that the sample value of the diagnosis signal is smaller than the third threshold value TH3, the ECU 40 sets the previous estimated plug drive voltage VG (i-1) as the current estimated plug drive voltage VG (i) (step). (See S17). The first threshold value to the third threshold value may be the same value or different values.

  In step S18, the ECU 40 calculates the base value of the duty of the energization control signal. Specifically, the ECU 40 calculates a duty for setting the temperature of the glow plug 20 to the target temperature on the assumption that the battery voltage indicates the reference value (for example, “12 V”). In subsequent step S19, the ECU 40 calculates a correction amount related to the duty of the energization control signal based on the estimated plug drive voltage VG (i). In the subsequent step S20, the ECU 40 calculates the final value of the duty of the energization control signal by correcting the base value of the duty of the energization control signal based on the correction amount calculated in step S18.

  Next, the operation of the engine system will be described based on the timing chart of FIG. 6, (a) is an energization control signal, (b) is a plug drive voltage, (c) is a diagnosis signal, (d) is a sample value of the diagnosis signal, (e) is a bit value of a bit string indicated by the diagnosis signal, (F) shows the estimated plug drive voltage, and (g) shows the correction coefficient related to the duty of the energization control signal. Here, the correction coefficient indicates “1” when the estimated plug drive voltage indicates the reference value VB of the battery 21, and when the estimated plug drive voltage is smaller than the reference value VB of the battery 21 If the estimated plug drive voltage is larger than the reference value VB of the battery 21, the correction amount indicates a value smaller than "1" corresponding to the difference. It is. The ECU 40 calculates the final value of the duty of the signal by multiplying the correction coefficient by the base value of the duty of the energization control signal.

  In FIG. 6A, a graph indicated by a broken line indicates an energization control signal when the duty is a base value, and a graph indicated by a solid line indicates that the duty is a final value (the base value is corrected based on the plug drive voltage). The energization control signal in the case of Further, in FIG. 6, it is assumed that the duty base value of the energization control signal is constant (the target temperature of the glow plug 20 is constant), and that the information bits of the diagnosis signal all indicate 0. Yes. Further, it is assumed that the plug drive voltage gradually decreases after timing t3. However, the plug drive voltage is assumed to be equal to or higher than the second threshold value TH2 and the third threshold value TH3 even after the timing t3.

  At timing t1, the plug drive voltage indicates the battery voltage reference value VB (see FIG. 6B), and the diagnosis signal indicates the high level (plug drive voltage) (see FIG. 6C). Therefore, the sample value of the diagnosis signal indicates the reference value VB of the battery voltage (see FIG. 6D). As a result, the bit value of the bit string indicated by the diagnosis signal is determined to be “1” (see FIG. 6E), and the estimated plug drive voltage is set to the battery voltage reference value VB (see FIG. 6F). In this case, since the difference between the estimated plug drive voltage and the battery voltage reference value VB is 0, the correction coefficient related to the duty of the energization control signal is 1 (see FIG. 6G).

  At timings t2 to t4, the diagnosis signal (start bit and information bit) indicates a low level. Therefore, the sample value of the diagnosis signal is smaller than the second threshold value TH2 and the third threshold value TH3 regardless of the plug drive voltage. As a result, the bit value of the bit string indicated by the diagnosis signal is determined to be “0”, and the estimated plug drive voltage is complemented by the estimated plug drive voltage at timing t1.

  After timing t5, the diagnosis signal indicates a high level, and the plug drive voltage is lower than the battery voltage reference value VB. Therefore, the sample value of the diagnosis signal is smaller than the battery voltage reference value VB. As a result, the correction coefficient relating to the duty of the energization control signal shows a value larger than 1, and the base value of the duty of the energization control signal is corrected based on the correction coefficient (see FIG. 6A).

  According to the embodiment described in detail above, the following excellent effects can be obtained.

  Based on the voltage of the power supply path to the glow plug 20, the energization of the plug 20 is interrupted. Here, the power supplied to the glow plug 20 is set according to the energization amount to the plug 20 and the voltage of the power supply path to the plug 20. Further, it is conceivable that the power consumption of the glow plug 20 is considerably larger than the power consumption of the ECU 40. In this case, when the electrical resistance of the glow plug 20 or the harness 22 changes with aging, the change in the plug drive voltage becomes large. In contrast, as described above, the power supply to the glow plug 20 is intermittently energized based on the voltage of the power supply path to the glow plug 20, so that the power supplied to the glow plug 20 is accurately controlled to the power corresponding to the target temperature. As a result, the temperature error of the plug 20 can be suppressed. In addition, since the ECU 40 controls the temperature of the glow plug 20 as described above, it is not necessary to provide dedicated hardware for controlling the switch unit 32 of the GDU 30 based on the voltage of the power supply path to the glow plug 20. Thereby, the number of parts can be reduced and the cost can be reduced.

  In addition, since the voltage of the power supply path to the glow plug 20 is superimposed on the diagnosis signal, a new hardware (for example, a cable for transmitting the voltage of the power supply path to the glow plug 20 from the GDU 30 to the ECU 40 and its A temperature error of the glow plug 20 can be suppressed without adding a connector for connecting a cable.

  In addition, when the switch unit 32 or the glow plug 20 is normal, the information bit of the diagnosis signal is set to a high level, and the switch unit 32 or the glow plug 20 is normal. The information bit of the diagnosis signal is set to low level. Here, it is considered that the judgment results of the switch unit 32 and the glow plug 20 are more normal than normal. Therefore, by assigning the determination results of the switch unit 32 and the glow plug 20 to the information bits of the diagnosis signal as described above, the period during which the voltage of the power supply path to the glow plug 20 is superimposed on the electrical signal can be extended. .

  In addition, a stop bit that always indicates a high level is included in the diagnosis signal. Thereby, the voltage of the power supply path to the glow plug 20 can be reliably acquired from the signal level corresponding to the stop bit of the diagnosis signal.

  Further, when the voltage of the power supply path to the glow plug 20 is not superimposed on the diagnosis signal (when the diagnosis signal is at low level), the voltage of the power supply path acquired previously (sample when the diagnosis signal is at high level) Value) is the voltage of the current power supply path. Thus, by complementing the voltage of the power supply path to the glow plug 20, even if the voltage of the power supply path is not superimposed on the electrical signal, it is based on the complemented voltage of the power supply path. Thus, the temperature of the glow plug 20 can be controlled.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be implemented as follows, for example.

  In the above embodiment, the voltage of the power supply path to the glow plug 20 is superimposed on the diagnosis signal in the GDU 30, and the voltage of the power supply path is acquired via the signal line 36 in the ECU 40. However, the voltage of the power supply path to the glow plug 20 may be acquired by any path as long as it is acquired via a signal line or a power line connected to the power supply path. For example, as illustrated in FIG. 7, a dedicated cable 50 that connects the power supply path to the glow plug 20 and the ECU 40 may be provided, and the voltage of the power supply path may be acquired via the cable 50.

  Moreover, in the said embodiment, when the switch part 32 or the glow plug 20 has shown that it is normal, the corresponding information bit of a diagnostic signal is made into a high level, and the switch part 32 or the glow plug 20 is normal. , The corresponding information bit of the diagnosis signal is set to the low level. However, when the switch unit 32 or the glow plug 20 is normal, the corresponding information bit of the diagnosis signal is set to a low level to indicate that the switch unit 32 or the glow plug 20 is normal. In addition, the information bit corresponding to the diagnosis signal may be set to the high level.

  In the above-described embodiment, the stop bit that always indicates the high level is included in the diagnosis signal (electric signal indicating the bit string), but the bit string that always indicates the high level may not be included. Further, the bit that always indicates a high level is not limited to a stop bit, and may be included in, for example, an information bit.

  In the above embodiment, the final value is calculated by correcting the base value of the duty of the energization control signal based on the voltage of the power supply path of the glow plug 20. However, the final value of the duty of the energization control signal may be directly calculated from the voltage of the power supply path of the glow plug 20.

  The internal combustion engine is not limited to a compression ignition type internal combustion engine such as a diesel engine. That is, even in a spark ignition type internal combustion engine such as a gasoline engine, when a heating element is provided in the combustion chamber in order to compensate for a decrease in the ignitability of the fuel at the start in a low temperature state, the present invention is applied to the temperature control. It is effective to apply The power source is not limited to a battery, and may be a generator or a fuel cell, for example.

The figure for demonstrating the engine system of this embodiment. The figure for demonstrating this embodiment GDU. The figure for demonstrating a diagnosis signal. The figure for demonstrating the abnormality detection part of GDU. The flowchart which shows the flow of a duty calculation program. The timing chart for demonstrating the action | operation of this embodiment. The figure for demonstrating other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Diesel engine (internal combustion engine), 11 ... Intake passage, 12 ... Intake valve, 14 ... Piston, 15 ... Combustion chamber, 16 ... Fuel injection valve, 17 ... Crankshaft, 18 ... Exhaust valve, 19 ... Exhaust passage, 20 ... Glow plug (heating element), 21 ... Battery (power source, secondary battery), 22 ... Harness (power supply path), 23 ... Harness (power supply path), 24 ... Crank angle sensor, 25 ... Water temperature sensor, 30 ... GDU (heating element driving device), 31... Switch unit, 32 .. abnormality detecting unit, 37... Judgment circuit, 38 .. output circuit, 40 .. ECU (control device), 39.

Claims (9)

A heating element that is provided in the combustion chamber of the internal combustion engine and generates heat according to the supplied power, a power source that supplies power to the heating element, and a power supply path from the power source to the heating element that passes through the power supply path A temperature control system comprising: a heating element driving device for intermittently energizing the heating element; and a control device for intermittently energizing the heating element by the heating element driving device so as to control power supplied to the heating element. In
The said control apparatus acquires the voltage of the said electric power supply path | route, and controls the said heat generating body drive device based on the acquired voltage, The temperature control system of the heat generating body characterized by the above-mentioned. In the temperature control system, wherein the heating element driving device has an output circuit that outputs an electrical signal to the control device,
The output circuit superimposes the voltage of the power supply path on the electrical signal,
2. The temperature control system for a heating element according to claim 1, wherein the control device controls the heating element driving device based on a voltage of the power supply path superimposed on the electrical signal by the output circuit.   3. The temperature control system for a heating element according to claim 2, wherein the output circuit outputs a bit string in which a signal level at a high level indicates a voltage of the power supply path as an electric signal on which the voltage of the power supply path is superimposed. . The heating element driving device further includes a determination circuit for determining presence or absence of abnormality in the device,
4. The heating element temperature control system according to claim 3, wherein the output circuit includes a bit indicating whether or not there is an abnormality in the heating element driving device determined by the determination circuit in the bit string. 5.   The output circuit sets the corresponding bit of the bit string to a high level when the determination result by the determination circuit indicates normal, and the corresponding bit of the bit string when the determination result by the determination circuit indicates abnormality The temperature control system for a heating element according to claim 4, wherein the temperature is set to a low level.   The temperature control system for a heating element according to any one of claims 3 to 5, wherein the output circuit includes a bit that always indicates a high level in the bit string. A signal line for transmitting the electrical signal is connected to the power supply path;
The output circuit includes a switching element that opens and closes a connection between the signal line and the ground, and opens a connection between the signal line and the ground by the switching element so that a bit of the bit string is set to a high level. The temperature control system for a heating element according to any one of claims 3 to 6, wherein a bit of the bit string is set to a low level by closing the signal line and the ground by an element.   When acquiring the voltage of the power supply path every time, when the voltage of the power supply path is not superimposed on the electrical signal, the control device obtains the voltage of the power supply path acquired last time. The temperature control system for a heating element according to any one of claims 2 to 8, wherein the temperature is a voltage of the power supply path.   The temperature control system for a heating element according to any one of claims 1 to 9, wherein the power source is a secondary battery.

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