JP5350761B2 - Heater energization control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater energization control apparatus capable of performing correction with high accuracy to a difference in individual properties of heating resistors of a heater in which energization is controlled by a resistance value control method. <P>SOLUTION: A pre-correction resistance value necessary for calculating a target resistance value of a heating resistor applied as a control target when performing the PI control of heat-retention energization (S73) to the heating resistor in which a resistance value is changed according to a temperature change with a positive correlation is acquired when an engine is stopped (S41:NO). Thus, the acquired corrected resistance value is not affected by disturbance which is generated accompanied by the drive of the engine, and the temperature of the heating resistor can be kept at a target temperature with high accuracy by controlling the energization to the heating resistor by using the target resistance value calculated (S71) on the basis of the corrected resistance value and water temperature information. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a heater energization control device that controls energization of a heater having a heating resistor that generates heat when energized.

  Conventionally, a heater having a heating resistor that generates heat by energization is used in an automobile, for example, for engine start assistance and stable driving, or for heating a vehicle interior. As the heat generating resistor, those having a positive correlation in which the resistance value increases as the temperature of the heating resistor increases are widely used. When energizing such a heating resistor, in the initial stage of energization, the temperature of the heating resistor is low, so the resistance value is small and a relatively large current flows. If the resistance value increases as the temperature of the heating resistor increases, the current flowing through the heating resistor also decreases. Therefore, in recent years, there has been developed a device in which the resistance value of the heating resistor is further reduced and the temperature can be increased rapidly so that a larger current flows.

  As a control method for energizing a heater having such a heating resistor, a constant power control method and a resistance value control method are known. In the constant power control method, the supplied electric power is obtained from the voltage applied to the heating resistor and the flowing current, and the heater is energized so that the integrated electric energy obtained by integrating the electric power becomes a predetermined electric energy. Control method. According to the constant power control method, the heating resistor generates heat according to the amount of electric power input. Therefore, when a predetermined amount of power is input, the temperature of the heating resistor can be set to a predetermined temperature. Easy to manage temperature. This is because the heat generation amount (that is, temperature) of the heating resistor largely depends on the material of the material constituting the heating resistor, and it is industrially easy to make the material of the heating resistor uniform. The constant power control method is particularly suitable for preventing an excessive temperature rise in the initial stage of energization of the heating resistor, but the heating resistor has a temperature influence from the outside, for example, when the heating resistor is cooled by a disturbance. If received, it is difficult to maintain that temperature.

  On the other hand, the resistance value control method utilizes the fact that the temperature of the heating resistor and the resistance value have a positive correlation as described above, and the target value corresponding to the temperature at which the resistance value of the heating resistor becomes the temperature increase target. This is a method for controlling energization to the heating resistor so as to approach the resistance value. According to the resistance value control method, there is an advantage that the temperature of the heating resistor can be easily kept constant even if the heating resistor is affected by a temperature change due to disturbance. However, even if the resistance value of the heating resistor is the same as the material constituting the heating resistor, a characteristic difference may occur due to a slight change in the cross-sectional area or density of the heating resistor due to product tolerances. For this reason, even if the heating resistors have the same product number, differences (variations) due to differences in individual characteristics occur in the correlation between temperature and resistance value.

  Thus, for example, a glow plug energization control device used in a diesel engine performs glow plug energization control with a constant power control system at the time of engine start with little fluctuation in disturbance, and targets the temperature of a heating resistor (resistance heating heater). The temperature is raised to And after temperature rising, it switches to a resistance value control system, and the energization control of a glow plug is performed by maintaining the target temperature of a heating resistor (for example, refer patent document 1).

By the way, if the correlation between the temperature and the resistance value in the heating resistor is corrected for each heating resistor, the correlation between the temperature and the resistance value should be constant regardless of the difference in individual characteristics. Can do. That is, even if the resistance value control method is used, it is easy to raise the temperature of the heating resistor to the target temperature. In order to correct this, a constant power control method is used, power is applied so that the temperature of the heating resistor becomes a predetermined temperature, and the resistance value of the heating resistor at that time is measured. Furthermore, in order to make the conditions for temperature changes due to disturbances the same, information on environmental temperature such as water temperature and outside air temperature is acquired. And it is good to correct | amend the characteristic of the present heating resistor so that it may correspond with the correlation of the resistance value and temperature of the heating resistor which were measured beforehand at the same environmental temperature. As described above, since the temperature of the glow plug is raised by the constant power control method when the engine is started, if the correction condition is acquired during the temperature increase and the correction value is calculated from the acquired condition, the correction value Can be used for resistance value control after temperature rise.
JP 2004-44580 A

  However, when starting (cranking) of the engine itself is started during the temperature rise, the heat generating resistor of the glow plug may be partially cooled by swirl or injected fuel generated in the combustion chamber. In such a case, the resistance value of the heating resistor changes, but the environmental temperature information may not change, and the current heating resistor has the resistance value of the heating resistor measured during temperature rise. There is a possibility that the accuracy may not be obtained even if correction is performed on the above characteristics.

  The present invention has been made to solve the above-described problems, and is a heater that can accurately correct differences in the individual characteristics of the heating resistors of the heater that controls energization by a resistance value control method. An object is to provide an energization control device.

  The heater energization control device according to the present invention is a heater having a heating resistor that generates heat when energized and changes its own resistance value with a positive correlation according to its own temperature change. Is a heater energization control device that controls energization of the heating resistor by a resistance value control system that controls energization so that the value matches the target resistance value, and the drive of the internal combustion engine to which the heater is attached is stopped Sometimes, the first acquisition means for energizing the heating resistor to acquire the first resistance value of the heating resistor and the environment in which the heater is used when acquiring the first resistance value Environmental information acquisition means for acquiring environmental temperature information, calculation means for calculating the target resistance value based on the first resistance value and the environmental temperature information, and when the internal combustion engine is driven , To match the target resistance value calculated by said calculating means, and a current supply control means for controlling the energization of the heating resistor.

  According to the present invention, since the acquisition of the first resistance value used for calculating the target resistance value is performed when the driving of the internal combustion engine is stopped, the influence of the disturbance that may be caused when the heating resistor drives the internal combustion engine. By receiving (for example, cooling of the heating resistor by swirl or fuel injection, etc.), the temperature of the heating resistor, and hence the resistance value, does not change temporarily. Therefore, the accuracy of the acquired first resistance value is high, and the heating resistor is energized so as to coincide with the target resistance value calculated based on the first resistance value and the environmental temperature information. Control for maintaining the temperature of the resistor at the target temperature can be accurately performed.

  In addition, the heater energization control device according to the present invention may include determination means for determining whether or not the heater attached to the internal combustion engine has been replaced. Then, when it is determined by the determination means that the heater has been replaced, and the driving of the internal combustion engine is stopped, the first acquisition means acquires the first resistance value of the heating resistor. May be. In order to acquire the first resistance value, the heating resistor must be energized, and the energization is performed when the internal combustion engine is stopped. Will be accompanied by consumption. Therefore, as in the present invention, if the first resistance value is acquired only when the heater is replaced, energy consumption can be suppressed.

  In the heater energization control device according to the present invention, when the determination means determines that the heater has been replaced, the internal combustion engine is driven for the first time, and then the drive of the internal combustion engine is stopped. The first acquisition unit may acquire the first resistance value of the heating resistor. That is, the first resistance value is acquired after the first stop of the internal combustion engine after the heater replacement, so that the first time after the heater replacement is the first among the timings not affected by the disturbance as described above. A resistance value can be obtained.

  In the heater energization control device according to the present invention, after the determination unit determines that the heater has been replaced, before the first energization control of the heating resistor by the energization control unit is started. By now, it is preferable to provide setting means for setting an initial value for the first resistance value. When the internal combustion engine is driven for the first time after replacing the heater, the first resistance value corresponding to the new heating resistor is not acquired, but by setting the initial value to the first resistance value, the first resistance value is obtained. Energization of the heating resistor controlled using the target resistance value calculated based on one resistance value can be performed within a safe range in which excessive temperature rise is prevented. That is, the initial value is desirably a resistance value that limits energization to the heating resistors and can prevent overheating regardless of the characteristics of the individual heating resistors. The initial value is set to the first resistance value before energization control to the heating resistor is started for the first time after replacing the heater, that is, energization control (resistance value control) using the target resistance value is performed. It only needs to be completed before. Therefore, after the heater replacement, the initial value may be set when the internal combustion engine is not driven (for example, immediately after replacement), or when the heater is used for the first time (for example, when the engine key is turned on). Alternatively, the initial value may be set during the temperature rise toward the target temperature of the heating resistor. Further, an initial value may be set in advance at the time of the first shipment after the manufacture of the internal combustion engine.

  In addition, the heater energization control device according to the present invention includes a second acquisition means for energizing the heating resistor to acquire a second resistance value of the heating resistor, and the heating resistor based on the second resistance value. Deterioration detecting means for detecting the deterioration of the ink may be provided. When the deterioration detection unit detects the deterioration of the heating resistor, the first acquisition unit acquires the first resistance value every time the driving of the internal combustion engine is stopped, and the calculation unit The target resistance value may be calculated. After the deterioration of the heating resistor is detected, if the first resistance value is obtained and the target resistance value is calculated every time the driving of the internal combustion engine is stopped, the heating resistance is determined according to the degree of deterioration of the heating resistor. Even if the resistance value of the body fluctuates, the energization control of the heating resistor can be performed using a precise target resistance value that follows the resistance value.

  Further, in the heater energization control device according to the present invention, the constant power control in which the energization of the heating resistor by the first acquisition unit is a predetermined power amount that is an integrated power amount of power supplied to the heating resistor. It is good to do by the method. The integrated electric energy is an electric energy obtained by integrating the electric power calculated from the voltage applied to the heating resistor and the flowing current. Therefore, even if the resistance value varies due to differences in the characteristics of the heating resistor, under the same conditions (when there are no disturbances and the same conditions such as a constant ambient temperature obtained from the water temperature, etc.) A heat generation amount corresponding to the integrated power amount input to the heating resistor is obtained. That is, if the integrated electric energy supplied with respect to each heating resistor is the same, the temperature of each heating resistor is also the same. Therefore, in order to calculate the target resistance value by deriving the relationship between the temperature and the resistance value of each heating resistor, it is preferable to adopt a constant power control method for energizing the heating resistors.

  The heater may form a heat generating part of a glow plug used by being attached to the internal combustion engine.

  Hereinafter, an embodiment of a heater energization control device embodying the present invention will be described with reference to the drawings. In the present embodiment, as an example of a heater, a glow plug 20 used for assisting startup of a diesel engine (hereinafter also simply referred to as “engine”) 1 of an automobile and improving driving stability is given. A glow control unit (GCU) 30 that controls energization of the power supply will be described as an example of an energization control device.

  First, a schematic configuration of a system that controls energization of the glow plug 20 by the GCU 30 will be described with reference to FIG. FIG. 1 is a diagram illustrating an electrical configuration of a system that controls energization of the glow plug 20 by the GCU 30.

  In FIG. 1, only one glow plug 20 that is energized and controlled by the GCU 30 is shown. However, an actual internal combustion engine is provided with a plurality of cylinders. There are as many as there are. The energization control by the GCU 30 is performed independently for each glow plug, but the control method is the same. Therefore, in the description of the present embodiment, the energization control performed by the GCU 30 for any one glow plug 20 will be described below.

  A GCU 30 shown in FIG. 1 is a device for controlling energization of a glow plug 20 used for assisting start-up and improving driving stability of an automobile engine 1 as an example of an internal combustion engine. To be driven. The GCU 30 includes a microcomputer 31 having a known CPU 32, ROM 33, and RAM 34, and controls energization to the glow plug 20 according to various programs executed by the CPU 32.

  The microcomputer 31 has, as drive modes, a normal mode that is driven by an operation clock having a high oscillation frequency and a power saving mode that is driven by an operation clock having an oscillation frequency lower than that of the normal mode. The microcomputer 31 is shifted to the power saving mode when the driving of the engine 1 is stopped (the engine key 6 is OFF). In the power saving mode, the microcomputer 31 stops execution of various programs and waits for input of an interrupt signal. When an interrupt signal is input, the microcomputer 31 returns to the normal mode and executes various programs. Generally, initialization (for example, so-called initialization processing such as clearing of internal registers and RAM, resetting of ports and drivers, setting of addresses of processing programs at the time of interrupts, setting of various initial values such as flags and counters) is performed when the CPU 32 starts up. Done. In the microcomputer 31 according to the present embodiment, by mounting such a power saving mode, the CPU 32 can perform a quick drive (execution of a program, etc.) by omitting initialization when shifting to the normal mode.

  In the present embodiment, the microcomputer 31 has a built-in interrupt timer 36, and a signal periodically generated from the interrupt timer 36 (every 60 seconds in the present embodiment) is used as an interrupt signal. Is input. Further, the microcomputer 31 is configured to receive a signal (voltage) that reports whether the engine key 6 is ON or OFF, and this signal also functions as an interrupt signal in the power saving mode.

The GCU 30 is provided with a switch 37. The energization control to the glow plug 20 by the GCU 30 is performed by PWM control, and the switch 37 switches ON / OFF the energization to the heat generating resistor 21 of the glow plug 20 in accordance with an instruction from the microcomputer 31.
In the present embodiment, in order to calculate the resistance value of the heating resistor 21, this switch 37 is configured by connecting a FET (PROFET (registered trademark) manufactured by Infineon Technologies AG) having a current detection function via an NPN transistor. It is configured to drive. Of course, the switch 37 may be an FET having no current detection function. In such a case, for example, the current may be detected by calculating the current flowing through the shunt resistor connected in series with the heating resistor 21. Alternatively, when the energization is OFF in PWM control, a current is passed through a current detection resistor connected in parallel with the switch 37, and the resistance value of the heating resistor 21 is directly calculated based on the obtained partial pressure. A known method may be used.

  The GCU 30 is connected to an electronic control unit (ECU) 10 of the automobile by communication using CAN. A measured value of a water temperature sensor 5 that measures the coolant temperature of the engine 1 is input to the ECU 10, and the GCU 30 acquires a water temperature measurement result (water temperature information) from the ECU 10 via the CAN. In the present embodiment, the measurement result (water temperature information) of the water temperature sensor 5 obtained through the ECU 10 is used as the environmental temperature information described later, but the water temperature information can be obtained directly from the water temperature sensor 5. You may do it. Further, the environmental temperature information is not limited to the water temperature information. For example, the temperature information indicating a change according to the driving state of the engine, such as the exhaust gas temperature, the oil temperature, the outside air temperature in the vicinity of the engine 1, and the temperature of the engine 1 itself. May be used. The ECU 10 also receives a signal for reporting the ON / OFF state of the engine key 6 described above.

  Next, the glow plug 20 includes, for example, a heater 22 using a heating coil formed using a Fe—Cr alloy or a Ni—Cr alloy as a heating resistor 21 as a heating portion, and is attached to the engine 1. It is held by a mounting bracket 25 in which a screw is formed. The heating resistor 21 has a positive correlation in which the resistance value increases as the temperature of the heating resistor 21 increases (in other words, the resistance temperature coefficient has a positive value). As a glow plug, a type in which a heater formed by embedding a heat generation pattern formed using a high melting point material such as tungsten or molybdenum in a base made of an insulating ceramic and firing is used as a heat generation portion can also be used. . It is only necessary that the relationship between the temperature of the heating resistor and the resistance value has a positive correlation. Since the glow plug is known, detailed description thereof is omitted.

  One end of the heating resistor 21 is grounded via the mounting bracket 25 and the engine 1, and the other end is connected to the battery 4 via the switch 37 described above. That is, energization of the heating resistor 21 is performed by applying the voltage of the battery 4 by PWM control. Further, the other end side of the heating resistor 21 is connected to the microcomputer 31 via voltage dividing resistors 38 and 39 (resistance values R1 and R2 respectively). With this connection, a voltage Ve obtained by dividing the voltage Vg applied to the heating resistor 21 from the battery 4 is input to the microcomputer 31. In the microcomputer 31, the voltage Vg applied to the glow plug 20 can be obtained by Vg = {(R1 + R2) / R2} × Ve. Since the current Ig flowing through the heating resistor 21 is obtained from the switch 37 with a current detection function as described above, the microcomputer 31 sets the resistance value Rg of the heating resistor 21 to Rg = Vg / Ig. Can be obtained. Strictly speaking, the resistance value Rg of the heating resistor 21 includes the wiring resistance inside the glow plug 20 and on the energization path to the glow plug 20 (for example, an energization cable). In the following description, the resistance value Rg of the heating resistor 21 will be described.

  In the system configured to control the energization of the glow plug 20 by the GCU 30 configured as described above, the calibration of the correlation between the temperature and the resistance value of the heating resistor 21 is performed when the energization control of the glow plug 20 is performed. (Correction) is performed. Here, the principle of calibration will be briefly described.

  When not affected by a disturbance or the like, when a constant voltage is applied to the heating resistor, a current flows through the heating resistor to generate heat. Since the resistance value increases as the temperature of the heating resistor rises, the current flowing through the heating resistor gradually decreases. Therefore, if the applied voltage is constant, the electric power supplied to the heating resistor gradually decreases as the temperature rises. In other words, a curve is obtained in which the power decreases with the passage of time after the start of power supply to the heating resistor.

  Since the temperature of the heating resistor is low and the resistance value is small at the beginning of power supply, a relatively large current flows. As the temperature of the heating resistor increases, the resistance value increases and the flowing current is gradually suppressed. The temperature rise of the heating resistor often becomes non-uniform throughout the entire length, and the increase of the resistance value is not stable during the transition period of the temperature rise, but the resistance value becomes substantially constant when the temperature distribution approaches the equilibrium state. The temperature of the heating resistor is saturated.

  By the way, the resistance value of each heating resistor varies depending on various factors, and the relationship between the temperature and the resistance value is affected by the variation even if they have the same product number. However, the relationship between the integrated amount of input power and the amount of generated heat depends on the material of the heating resistor, and the variation is relatively small. Therefore, the reference heating resistor is energized, the temperature rise is saturated at the control target temperature (target temperature), and the integrated amount (integrated power amount) of input power up to that point is obtained. If this integrated power amount is input to a heating resistor to be calibrated (separate body), the temperature of the heating resistor as a target can be set as the target temperature. Therefore, the resistance value of the heating resistor to be calibrated at this time is obtained as the pre-correction resistance value corresponding to the target resistance value. If the PI control is performed so that the resistance value of the heating resistor to be calibrated becomes the target resistance value, the temperature of the heating resistor can be maintained at the target temperature.

  However, as described above, the resistance value of the heating resistor to be calibrated includes the wiring resistance inside the glow plug and on the energization path to the glow plug, and these resistance values also depend on the environment surrounding the glow plug. It changes according to the change of temperature. Here, according to the inventors, the relationship between the resistance value at the start of energization of the heating resistor and the resistance value at any timing during the temperature rise, and the resistance value when the temperature is saturated is It is known that there is a certain correlation (see Japanese Patent Application No. 2008-142459 for details). Therefore, in this embodiment, water temperature information is obtained as environmental temperature information, and when performing calibration, the pre-correction resistance value of the target heating resistor is acquired, and the water temperature information at that time is also acquired. ing. Then, when performing heat insulation energization (described later) by PI control using the target resistance value, water temperature information at that time is acquired, and a correction table or a correction arithmetic expression determined in advance based on the above correlation is applied. By doing so, the target resistance value is calculated by correcting the resistance value before correction to the water temperature, and energization control of the glow plug is performed. As described above, since the calibration is performed while the resistance value of the heating resistor includes the wiring resistance in the glow plug and on the energization path to the glow plug, the target resistance value with high accuracy can be calculated. Can do it.

  In the GCU 30, the above-described calibration of the glow plug 20 is performed on the newly installed glow plug 20 when it is detected that the glow plug 20 has been replaced (removed from the engine 1). ing. Then, the pre-correction resistance value obtained by calibration is applied to the glow plug 20 every time the engine 1 is driven (every time the glow plug 20 is used). In other words, the calibration for the glow plug 20 is not performed every time the engine 1 is driven. Therefore, in this embodiment, not only the energization control to the glow plug 20 is performed according to the energization control program described later, but also the replacement confirmation of the glow plug 20 (detection of whether or not the glow plug 20 has been replaced) is performed. Yes.

  By the way, the replacement of the glow plug 20 is performed when the engine 1 is stopped. However, when the engine 1 is stopped, the microcomputer 31 of the GCU 30 shifts to the power saving mode described above in order to suppress the consumption of the battery 4. In the power saving mode, execution of various programs including the energization control program is stopped. Therefore, in the present embodiment, the microcomputer 31 is shifted (returned) from the power saving mode to the normal mode with the input of an interrupt signal periodically issued from the interrupt timer 36 described above. Then, the energization control program is executed in the normal mode, and the exchange confirmation of the glow plug 20 is performed in the energization control program.

  Hereinafter, a specific example of the energization control performed by the GCU 30 on the glow plug 20 will be described according to the flowchart of the energization control program shown in FIGS. FIG. 2 is a flowchart of the main routine of the energization control program executed in the GCU 30. FIG. 3 is a flowchart of energization processing called from the main routine of the energization control program. FIG. 4 is a flowchart showing processing when an exchange check interrupt is performed. Each step of the flowchart is abbreviated as “S”.

  First, before describing energization control, various variables and flags used in the energization control program will be described. The following flags and variables are stored in an area secured in the RAM 34, but their values are retained unless the CPU 32 is initialized regardless of the drive mode of the microcomputer 31.

  The “check flag” is a flag that is set when the replacement confirmation (replacement check) of the glow plug 20 is performed. Specifically, a check flag is set when an interrupt signal is issued from the interrupt timer 36. In the energization control program, when it is confirmed that the check flag is established, a series of processes for confirming replacement of the glow plug 20 is performed.

  The “initial flag” indicates that execution of a specific processing portion (S45 to S55 described later) in the series of processes repeatedly executed when the engine key 6 is ON in the energization control program. This flag is used for determining the condition because it is executed only for the first time. The initial flag is established when the engine key 6 is turned on and a specific processing portion is executed, and is not established when the engine key 6 is turned off.

  The “exchange flag” is a flag that is set when it is detected that the glow plug 20 has been exchanged in a series of processing for confirming the exchange of the glow plug 20. In the energization control program, conditioning (establishment of a correction flag described later) is performed so that calibration for the glow plug 20 is performed when the replacement flag is established.

  The “correction flag” is a flag used for determination when performing calibration. As described above, the calibration is performed when it is detected that the glow plug 20 has been replaced. However, the calibration is also performed when the pre-correction resistance value obtained by calibration is in a clear state (that is, 0). Is called. Although the resistance value before correction is stored in the RAM 34, for example, when a situation occurs in which the RAM 34 is cleared, for example, when the battery 4 is replaced or at the first shipment, a new resistance value before correction is obtained by performing calibration. The correction flag is established.

  The “pre-correction resistance value” is a resistance value acquired by calibration, and the resistance value (target resistance value) of the heating resistor 21 corresponding to the temperature (target temperature) that is the target for maintaining (warming) the heating resistor 21 (target temperature). ) Is the resistance value of the heating resistor 21 that is the basis for the calculation. In the initial state (when the RAM 34 is cleared and the value is 0, such as at the first shipment or when the battery 4 is replaced), a predetermined initial value is set. The resistance value before correction corresponds to the “first resistance value” in the present invention.

  The “target resistance value” is obtained by correcting the resistance value before correction based on environmental temperature information (for example, water temperature information), and is used as a control target for maintaining the temperature of the heating resistor 21 at the target temperature. The resistance value of the heating resistor 21.

[Operation during normal operation]
Next, details of energization control for the glow plug 20 will be described. First, energization control performed on the glow plug 20 during normal operation (a state where calibration has already been performed and a resistance value before correction has been acquired) will be described. In this state, the check flag, the initial flag, the replacement flag, and the correction flag are all 0.

  As described above, the microcomputer 31 is shifted to the power saving mode in a state where the driving of the engine 1 is stopped (a state where the engine key 6 is OFF), and waiting for input of an interrupt signal. A case where an interrupt signal from the interrupt timer 36 is input in this power saving mode will be described later.

  As shown in FIG. 1, when the driver operates the engine key 6 to be turned ON, an interrupt signal for reporting the ON state is input to the microcomputer 31. Then, the operation clock of the microcomputer 31 is switched to one having a high transmission frequency in the normal mode, and the transition from the power saving mode to the normal mode is performed. With the transition to the normal mode, execution of the energization control program shown in FIG. 2 is started, and various settings necessary for performing energization control of the glow plug 20 in the normal mode are performed (S11). Further, an interrupt prohibition process is performed (S13), and thereafter, interrupt signals input to the microcomputer 31 are ignored.

  Next, the check flag is referred to. However, since the replacement check of the glow plug 20 is not performed in the normal operation, the check flag is not established (S15: NO), and the process proceeds to S31, and the energization processing subroutine of FIG. Called. As shown in FIG. 3, in the energization process, it is confirmed from the port voltage of the microcomputer 31 connected to the engine key 6 whether the engine key is ON (S41). As described above, the engine key 6 is operated to be ON (S41: YES), and the process proceeds to S43. Note that while the engine key 6 is ON (S41: YES), S43 to S75 are repeatedly executed to control the energization state (rapid temperature rise energization and heat insulation energization described later) of the glow plug 20. It will be different.

  When the first energization process is executed after returning to the normal mode, the initial flag is also set to 0 in the initial state (S43: NO). Since the initial flag is a flag for performing S45 to S55 only once after returning to the normal mode, 1 is stored in the initial flag in S45 so that the process can skip to S43 and proceed to S61. (S45).

  In S47, the resistance value before correction is read (reference value) (S47). As described above, the resistance value before correction is acquired when calibration is performed, and is stored in the RAM 34. If the pre-correction resistance value is not 0 (S49: NO), it means that calibration has already been performed (here, it is assumed that the pre-correction resistance value has already been acquired), and then the replacement flag. Is referred to (S51). Since the exchange flag is set when it is detected that the glow plug 20 has been exchanged (described later), it is not established here (S51: NO), and the process proceeds to S61.

  In S61 to S75, energization processing for the glow plug 20 is performed. Before energization of the heating resistor 21 is started and before the temperature of the heating resistor 21 reaches the temperature increase target temperature (S61: NO), energization (rapid increase) for quickly increasing the temperature of the heating resistor 21 is performed. (Warm energization) is performed (S63). The temperature increase target temperature is slightly lower than the temperature (target temperature) of the heating resistor 21 corresponding to the target resistance value, and heat is generated by slight energization after switching from constant power control to resistance value control. The temperature is set as a temperature increase target set so that the temperature of the resistor 21 can reach the target temperature.

  In this rapid temperature increase energization, the curve indicating the relationship between the electric power input to the heating resistor 21 and the elapsed time is matched with a curve that is a preliminarily created reference, so that the characteristics of the heating resistor 21 are obtained. Regardless, the temperature is raised rapidly (for example, 2 seconds) to the target temperature. Specifically, the value of electric power to be applied at each time point corresponding to the elapsed time from the start of energization is obtained using a predetermined relational expression or table of a curve as a reference. The voltage to be applied to the heating resistor 21 is obtained from the relationship between the magnitude of the current flowing through the heating resistor 21 and the power value to be applied at that time, and the voltage to be applied to the heating resistor 21 is determined by PWM control. Control. As a result, electric power that draws the same curve as the reference curve is input, and the heating resistor 21 generates heat according to the integrated amount of electric power that has been input up to each point in the temperature raising process. Therefore, if the input of power along the reference curve is completed, the heating resistor 21 reaches the temperature increase target temperature in the same time as the reference curve.

  Thereafter, the process returns to S41, and the process of S63 is repeated until the rapid temperature increase energization is completed, and the rapid temperature increase energization to the heating resistor 21 is continued (S41: YES, S43: YES, S61: NO, S63). Since the initial flag is established in S45, the process proceeds to S61 in the second and subsequent S43 (S43: YES).

  In this way, the electric power supplied to the heating resistor 21 is adjusted in the transition period of the rapid temperature increase energization, and the temperature of the heating resistor 21 reaches the temperature increase target temperature. In the present embodiment, the end timing of the rapid temperature increase energization is set when one of the following two conditions is satisfied. One is a case where the elapsed time from the start of rapid heating energization to the heating resistor 21 has reached a predetermined time (for example, 3.3 seconds). In this case, the temperature of the heating resistor 21 is increased. The target temperature has been reached. The other is a case where the resistance value Rg of the heating resistor 21 becomes a predetermined resistance value (for example, 780 mΩ). When the temperature of the heating resistor 21 is already high to some extent at the time when the power supply to the heating resistor 21 is started (for example, when re-energization is performed without being sufficiently cooled after the previous energization stop) When the resistance value Rg of the heating resistor 21 reaches a predetermined resistance value, the power supply is stopped, so that an excessive temperature rise of the heating resistor 21 can be prevented.

  If it is determined that any of the above conditions is satisfied and the rapid temperature increase energization has been completed while S41 to S63 are repeated and the rapid temperature increase energization is continued (S61: YES), it is based on PWM control. The power supply to the heating resistor 21 is stopped (S65). Here, in the present embodiment, heat insulation energization (so-called afterglow energization) is performed after rapid temperature increase energization, and the temperature of the heating resistor 21 is maintained at a target temperature corresponding to the target resistance value, thereby starting the engine 1. The drive stability afterwards is improved. This heat insulation energization is also determined to end when a predetermined time (for example, 180 seconds) elapses. Therefore, time keeping by a timer (not shown) is started together with the start of heat insulation energization, and before the predetermined time has elapsed (S67: NO), water temperature information is acquired from the water temperature sensor 5 via the ECU 10 for heat insulation energization (S69). ). Based on this water temperature information, the above-described water temperature correction is performed on the pre-correction resistance value stored in the RAM 34 to obtain a target resistance value (S71). Then, the heating resistor 21 is heated and energized by PI control that changes the duty ratio according to the difference between the resistance value Rg and the target resistance value so that the resistance value Rg of the heating resistor 21 approaches the target resistance value. (S73). Thereafter, the process returns to S41, and the process of S73 is repeated until the heat insulation energization is completed, and the heat insulation energization to the heating resistor 21 is continued (S41: YES, S43: YES, S61: YES, S67: NO, S73). In S71, the CPU 32 that performs water temperature correction (application of a predetermined correction table or correction calculation formula) to the resistance value before correction and obtains the target resistance value corresponds to the “calculation means” in the present invention. In S73, the CPU 32 that controls the heat conduction to the heating resistor 21 by the PI control corresponds to the “energization control means” in the present invention.

  When it is determined that the predetermined time (180 seconds) has elapsed while the heat insulation energization is continued while S41 to S73 are repeated and the heat insulation energization is completed (S67: YES), the power to the heating resistor 21 is reduced. The charging is stopped (S75). Thereafter, as long as the engine key 6 is ON, power is not supplied to the glow plug 20 (S41: YES, S43: YES, S61: YES, S67: YES).

  When the driver operates the engine key 6 and the drive of the engine 1 is stopped (S41: NO), the initial flag is reset so that the processing of S45 to S55 is performed at the next drive of the engine 1. (S77). Here, when the engine key 6 is operated to be OFF and the rapid temperature increase energization or heat insulation energization is being performed on the glow plug 20 (S79: YES), the energization is stopped (S79: YES) If not (S79: NO), the process proceeds to S83. In S83, the correction flag is referred to, but since the calibration has already been performed in the normal operation, the correction flag is not established (S83: NO), and the process directly returns to the main routine.

  As shown in FIG. 2, when the energization process of S31 is completed, an interrupt is permitted (S33), and an interrupt signal input to the microcomputer 31 is received again. After various settings necessary for shifting to the power saving mode are performed (S35), the operation clock of the microcomputer 31 is switched to one having a low transmission frequency in the power saving mode, and the transition from the normal mode to the power saving mode is performed. Is done. The operation of the energization control program is stopped.

[Operation when confirming replacement]
Next, a series of operations when confirmation of replacement of the glow plug 20 is performed will be described. The replacement confirmation of the glow plug 20 attached to the engine 1 is periodically performed when the engine 1 is not driven, that is, when the microcomputer 31 is in the power saving mode. In this embodiment, the replacement of the glow plug 20 is confirmed every 60 seconds, and this time interval (the time required for replacing the glow plug 20) is a new glow plug after the old glow plug 20 is removed from the engine 1. It is set to a time shorter than the time taken until 20 is attached. That is, when the glow plug 20 is replaced, the above time interval is set so that the replacement of the glow plug 20 is always performed once while the glow plug 20 is removed from the engine 1. Yes.

  When the microcomputer 31 is in the power saving mode, when the interrupt signal generated at the above time interval (every 60 seconds) is input from the interrupt timer 36 to the CPU 32, the interrupt signal is accepted and the microcomputer 31 receives the interrupt signal. The computer 31 shifts to the normal mode. When an interrupt signal is input from the interrupt timer 36, the exchange check interrupt processing program shown in FIG. 4 is executed and a check flag is established (S5). Therefore, when the energization control program shown in FIG. 2 is executed, the establishment of the check flag is confirmed in S15 (S15: YES), and a series of processing (S17 to S23) for confirming replacement of the glow plug 20 is performed. Is done.

  First, the heating resistor 21 is energized for a short time (for example, 25 msec), and the resistance value Rg of the heating resistor 21 is calculated (acquired) from the voltage Vg applied at that time and the flowing current Ig. (S17). Then, after resetting the check flag (S19), it is compared whether or not the resistance value Rg of the heating resistor 21 is greater than a predetermined threshold value (exchange determination value). When the glow plug 20 is removed from the engine 1, the heating resistor 21 does not exist, so that the current Ig does not flow, and the energization resistance to the heating resistor 21 becomes very large. Therefore, if the resistance value Rg of the heating resistor 21 is larger than the replacement determination value, it is determined that the glow plug 20 has been removed, that is, the glow plug 20 has been replaced (S21: YES), and the replacement flag is set. It is established (S23). However, if the resistance value Rg is equal to or less than the replacement determination value (S21: NO), it is determined that the glow plug 20 has not been replaced. Thereafter, the processing after S33 described above is performed to shift to the power saving mode. As described above, the replacement confirmation of the glow plug 20 is periodically performed in the power saving mode, and the replacement flag is established when it is detected that the replacement has been performed. In S21, the CPU 32 for determining whether or not the glow plug 20 has been replaced corresponds to the “determination means” in the present invention. Further, the CPU 32 that acquires the resistance value Rg of the heating resistor 21 in S17 corresponds to the “second acquisition means” in the present invention, and the resistance value Rg acquired at that time is the “second resistance in the present invention”. Corresponds to “value”.

[Operation during calibration]
Next, the operation at the time of performing calibration for the heating resistor 21 of the glow plug 20 will be described. As described above, the calibration of the glow plug 20 is performed when it is detected that the glow plug 20 has been replaced (when the replacement flag is established), or when the pre-correction resistance value is in the clear state (the value is 0). For example, this is performed when the engine 1 is not driven in order to avoid the influence of disturbance such as swirl or cooling by fuel. Further, in the calibration, the heating resistor 21 is heated to the same level as the temperature that is heated when the engine 1 is started. Therefore, when replacement of the glow plug 20 is detected in the power saving mode of the microcomputer 31, the engine 1 is driven next time and then stopped (that is, when the battery 4 is expected to be charged). In addition, calibration is performed.

  Therefore, when the engine key 6 is operated to be turned on and the engine 1 is driven, the normal energization control of the glow plug 20 is performed as shown in FIG. 3 after returning to the normal mode (S41 to S41). S75). Similarly to the above, when the processes of S41 to S75 are performed for the first time after the engine key 6 is turned on, the initial flag is 0 (S43: NO), so S45 to S55 are executed. At this time, if the replacement flag is established (S51: YES) or the pre-correction resistance value is in a clear state (S49: YES), the correction flag is established and the replacement flag is reset (S53). ). Since the resistance value before correction stored in the RAM 34 at this time is that of the heating resistor 21 of the glow plug 20 before replacement, an initial value is set as the resistance value before correction (S55). The energization process for the glow plug 20 described above is performed (S61 to S75). It should be noted that the initial value set as the pre-correction resistance value is an excess value for any heating resistor even if the resistance value of another heating resistor with different characteristics is controlled using the target resistance value calculated from the initial value. It is predetermined so as not to raise the temperature. The CPU 32 that sets an initial value for the correction resistance value corresponds to the “setting means” in the present invention.

  As described above, the engine key 6 is turned on for the first time and the engine 1 is driven after the replacement of the glow plug 20 or after the pre-correction resistance value is cleared (for example, when the vehicle is shipped for the first time or when the battery 4 is replaced). In this case, energization control of the glow plug 20 is performed as usual. When the engine key 6 is turned off (S41: NO), since the correction flag is established this time, the process proceeds to S85 in S83 and calibration is performed (S83: YES).

  As described above, in the calibration, the heating resistor 21 is supplied with an integrated amount of electric power (integrated electric energy) that can obtain the target temperature, and the temperature rise of the heating resistor 21 is saturated, and the temperature is the target temperature. The resistance value Rg when stabilized at is acquired as the resistance value before correction. In the present embodiment, it is considered that the temperature rise of the heating resistor 21 is saturated with the passage of time (for example, 60 seconds) from the start of calibration. Therefore, when calibration is started, a timer (not shown) is started and until the time required for saturation elapses (S85: NO), the final integrated power amount becomes the integrated power amount for the heating resistor 21. In such a manner, correction energization is performed in which constant power is applied per hour (S87). Then, it returns to S41 and continues correction | amendment electricity supply.

  When S41: NO, S83: YES, S85: NO, and S87 are repeated, if 60 seconds (time when the temperature rise of the heating resistor 21 can be regarded as saturated) have elapsed after the start of the correction energization (S85: YES), Proceed to S89. Since the temperature of the heating resistor 21 has reached the target temperature, the resistance value Rg of the heating resistor 21 at that time is obtained and stored in the RAM 34 as a resistance value before correction (S89). Furthermore, the water temperature information of the water temperature sensor 5 is acquired from the ECU 10, and stored in the RAM 34 together with the pre-correction resistance value (S91). Then, the correction flag is reset assuming that the calibration is completed (S93), the energization of the heating resistor 21 is stopped, the correction energization is terminated (S95), and the process returns to the main routine of FIG. Note that the CPU 32 that acquires the pre-correction resistance value in S89 after performing the correction energization in S87 and supplying the heating resistor 21 with an integrated amount of electric power (integrated electric energy) for obtaining the target temperature. Corresponds to “first acquisition means” in FIG. In S91, the CPU 32 that acquires the water temperature information of the water temperature sensor 5 via the ECU 10 corresponds to the “temperature acquisition means” in the present invention.

  Returning to the main routine shown in FIG. 2, the interrupt is permitted in the above-described processing of S33, and after making various settings in S35, the shift to the power saving mode is performed. The operation of the energization control program is stopped. When the engine key 6 is turned ON while calibration is being performed (while the above-described correction energization is being performed), rapid temperature increase energization and heat insulation energization are performed. Become. However, since the calibration has not been completed, the pre-correction resistance value is not acquired, the initial value is set as the pre-correction resistance value, and the energization control of the glow plug 20 is performed. Therefore, after that, when the engine key 6 is turned off, calibration is performed again.

  Needless to say, the present invention is not limited to the above embodiment, and various modifications are possible. For example, the deterioration of the heating resistor 21 may be detected as in the first modification of the energization control program shown in FIG. The first modification of the energization control program of FIG. 5 is obtained by adding an additional process for detecting deterioration of the heating resistor 21 between S23 and S33 in the energization control program of FIG. Moreover, what added the additional process performed when deterioration is detected between S55 and S61 in the electricity supply process of FIG. 3 is shown in FIG. 6 as a modification of an electricity supply process.

  In the first modification, the deterioration of the heating resistor 21 is detected by looking at the change in the energization resistance to the heating resistor 21. The resistance value of the heating resistor 21 increases, for example, at room temperature as the deterioration state progresses. However, the resistance value does not increase with the progress of the deterioration state, but rapidly increases when the deterioration state progresses to some extent. It is known that the resistance value is increased. Therefore, as shown in FIG. 5, the deterioration detection of the heating resistor 21 is performed when the resistance value Rg of the heating resistor 21 obtained in S17 is higher than a predetermined deterioration determination value. It is determined that deterioration has occurred (S25: YES), a deterioration flag (a flag indicating the determination result of deterioration) is established (S27), and the process proceeds to S33. If the resistance value Rg is equal to or less than the deterioration determination value (S25: NO), the process proceeds to S33 as it is. However, as described above, if the resistance value Rg of the heating resistor 21 is greater than the replacement determination value, it is determined in S21 that the glow plug 20 has been replaced. Although the deterioration detection of the heat generating resistor 21 is performed after confirming the replacement of the glow plug 20, in S25, the deterioration detection condition is that the resistance value Rg is equal to or less than the replacement determination value. After detecting the presence or absence of deterioration in S25 and S27, the process proceeds to S33. Note that the CPU 32 that determines that the heating resistor 21 has deteriorated in S25 corresponds to the “deterioration detecting means” in the present invention.

  In the energization process of FIG. 6 that is executed when the engine key 6 is turned on, the state of the deterioration flag is confirmed following the processes of S45 to S55 that are executed only for the first time when the engine key 6 is turned on. (S57). If the deterioration flag is not established, the process proceeds to S61 as it is (S57: NO). If the deterioration flag is established (S57: YES), the correction flag is established, the deterioration flag is reset, and the process proceeds to S61. (S59). As a result, as in the case where the exchange flag described above is established, when the engine key 6 is turned on and then turned off (S41: NO), calibration is performed (S83: YES). ). Note that the deterioration detection of the heating resistor 21 is performed every time the glow plug 20 is confirmed to be replaced while the engine key 6 is OFF and the microcomputer 31 is in the power saving mode. Therefore, after the heating resistor 21 is in a deteriorated state and the resistance value is greater than the deterioration determination value, unless the heating resistor 21 is replaced with a non-degraded one by replacing the glow plug 20, each time the deterioration is detected, It will be determined that it is in a deteriorated state. Therefore, calibration is performed every time the engine 1 is driven and stopped, and the target resistance value is calculated each time, so that the latest target resistance value corresponding to the deterioration state is maintained.

  However, immediately after the engine 1 is stopped, the temperature of the heating resistor 21 is high and the resistance value Rg is high. Therefore, the water temperature information may be acquired from the ECU 10, and the resistance value Rg may be corrected based on the water temperature, and then compared with the deterioration determination value. Alternatively, even when the temperature of the cooling water is in a predetermined water temperature (for example, 25 ° C.) or a water temperature range (for example, 0 ° C. to 25 ° C.), the resistance value Rg and the deterioration determination value are compared to perform the deterioration determination. Good. Alternatively, the deterioration determination may not be performed until it is determined that a predetermined time has elapsed after the engine 1 is stopped and the water temperature has dropped below the predetermined temperature.

  Further, as in the second modification of the energization control program shown in FIG. 7, the resistance value Rg of the heating resistor 21 obtained in S17 when confirming the replacement of the glow plug 20 is stored in the RAM 34 (S29), It may be stored. Thereby, the resistance value Rg of the heating resistor 21 obtained at the time of the previous replacement confirmation and the resistance value Rg of the heating resistor 21 obtained at the time of the current replacement confirmation can be compared. Furthermore, the comparison result can be used for confirmation of replacement of the glow plug 20. For example, using the fact that the resistance value Rg of the heating resistor 21 is increased as the heating resistor 21 is deteriorated, the current replacement confirmation is more than the resistance value Rg of the heating resistor 21 obtained at the previous replacement confirmation. When the resistance value Rg of the heating resistor 21 obtained at this time is low, it can be detected that the glow plug 20 has been replaced. And if it is this detection method, it can determine with having replaced | exchanged irrespective of the detection by regular electricity supply. Then, the replacement confirmation interval (interval at which the interrupt timer 36 outputs an interrupt signal) can be lengthened and the frequency of replacement confirmation can be lowered, so that the consumption of the battery 4 can be reduced. As in the first modification, the resistance value Rg of the heating resistor 21 changes depending on the temperature of the heating resistor 21 at the time of acquisition. Therefore, the replacement determination is performed after correcting the resistance value Rg with the water temperature. Alternatively, as described above, the resistance value Rg may be acquired and the replacement determination may be performed only when the water temperature is within a predetermined water temperature or water temperature range. Alternatively, the replacement determination may not be performed until it is considered that the predetermined time has elapsed after the engine 1 is stopped and the water temperature has dropped below the predetermined temperature. In addition, although a detailed description is omitted, if the heating resistor has a resistance value that gradually changes as the heater deteriorates, the deterioration flag is changed and the deterioration determination value is changed, and the calibration is performed again. Needless to say, it can be done. It is essential in the present invention that the calibration is performed when the engine is stopped, and the means for detecting the replacement of the heater is not limited in any way.

  In the present embodiment, in S87, the saturation of the temperature rise at the time of calibration is determined over time, but the resistance value Rg of the heating resistor 21 is continuously acquired during the correction energization, and the resistance When the fluctuation of the value Rg becomes smaller than a predetermined value, it may be determined that the value is saturated.

It is a figure which shows the electrical constitution of the system which performs electricity supply control to the glow plug 20 by GCU30. It is a flowchart of the main routine of the electricity supply control program performed in GCU30. It is a flowchart of the electricity supply process called from the main routine of an electricity supply control program. It is a flowchart which shows the process at the time of exchange check interruption. It is a flowchart of the electricity supply control program of a 1st modification. It is a flowchart of the electricity supply process of a 1st modification. It is a flowchart of the electricity supply control program of a 2nd modification.

Explanation of symbols

1 Engine 20 Glow Plug 21 Heating Resistor 22 Heater 30 GCU
31 Microcomputer 32 CPU

Claims (7)

For a heater having a heating resistor that generates heat when energized and its resistance value changes with a positive correlation according to its own temperature change, energization is performed so that the resistance value of the heating resistor matches the target resistance value. A heater energization control device for controlling energization to the heating resistor by a resistance value control method for controlling,
First acquisition means for energizing the heating resistor to acquire a first resistance value of the heating resistor when driving of the internal combustion engine to which the heater is attached is stopped;
Environmental information acquisition means for acquiring environmental temperature information according to the environment in which the heater is used when acquiring the first resistance value;
Calculation means for calculating the target resistance value based on the information on the first resistance value and the environmental temperature;
Energization control means for controlling energization of the heating resistor so as to coincide with the target resistance value calculated by the calculation means when the internal combustion engine is driven. apparatus. Determining means for determining whether or not the heater attached to the internal combustion engine has been replaced;
The first acquisition means acquires the first resistance value of the heating resistor when it is determined by the determination means that the heater has been replaced, and the driving of the internal combustion engine is stopped. The energization control device for a heater according to claim 1, wherein the heater is energized.   The first acquisition means is configured such that when the internal combustion engine is driven for the first time after the determination means determines that the heater has been replaced, and then the drive of the internal combustion engine is stopped, The heater energization control apparatus according to claim 2, wherein the first resistance value is acquired.   After the determination means determines that the heater has been replaced, an initial value is set to the first resistance value before the first energization control of the heating resistor is started by the energization control means. The heater energization control device according to claim 3, further comprising a setting unit configured to perform the setting. A second acquisition means for energizing the heating resistor and acquiring a second resistance value of the heating resistor;
Deterioration detecting means for detecting deterioration of the heating resistor based on the second resistance value,
When deterioration of the heating resistor is detected by the deterioration detection unit, the first acquisition unit acquires the first resistance value every time the driving of the internal combustion engine is stopped, and the calculation unit sets the target The heater energization control apparatus according to claim 1, wherein a resistance value is calculated.   The energization of the heating resistor by the first acquisition unit is performed by a constant power control method in which an integrated power amount of power input to the heating resistor is a predetermined power amount. The heater energization control device according to any one of claims 5 to 6.   The heater energization control device according to any one of claims 1 to 6, wherein the heater forms a heat generating part of a glow plug used by being attached to the internal combustion engine.

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