JP2005240707A - Grow plug power supply control device and grow plug power supply control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grow plug power supply control device and a grow plug power supply control method for rapidly raising temperature of a resistance heating heater in an intermediate temperature raising grow step. <P>SOLUTION: A grow plug power supply control device 101 comprises a post-starting grow means for stably heating a ceramic heater 2 after starting of an engine and an intermediate temperature raising grow means for controlling power supply to a grow plug 1 so that temperature of the ceramic heater 2 is raised to and kept at a target temperature after power supply control by the post-starting grow means is stopped. The intermediate temperature raising grow means has a first intermediate temperature raising means for calculating a duty ratio Dt1 of a voltage waveform to be applied to the grow plug 1 based on a target resistance value Ro according to the target temperature for the ceramic heater 2 and for PWM-controlling the power supply to the grow plug 1 with the duty ratio Dt1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a glow plug energization control device and a glow plug energization control method for controlling energization to a glow plug that assists in starting an internal combustion engine.

A glow plug generally uses a resistance heater. This glow plug is configured by attaching a resistance heating heater to a metal shell, and is used by being attached to an engine block of a diesel engine so that the tip of the resistance heating heater is located in the combustion chamber.
A glow plug energization control device is known as a device for controlling the energization of such a glow plug. In the conventional glow plug energization control device, when the key switch is turned on, the resistance of the resistance heater is increased to a temperature sufficient to start the engine (for example, 1250 ° C.). Controls energization and supplies large power to the glow plug. Such a step is generally called a pre-glow or a pre-glow step. With a glow plug capable of rapid heating, the resistance heater can be raised to the above temperature within a few seconds.

  After the resistance heating heater reaches the above temperature, the energization to the glow plug is controlled so that the temperature of the resistance heating heater is maintained at a predetermined temperature (for example, 1250 ° C.) for a predetermined time (for example, 80 seconds), Supply small power to the glow plug. Such a step is generally called afterglow or afterglow step. Before starting the engine, keep the resistance heating heater at a sufficiently high temperature so that the engine can be started at any time.After starting the engine, it promotes warming up in the combustion chamber of the engine and prevents the occurrence of diesel knock. Noise, generation of white smoke, emission of HC components can be suppressed.

  Normally, the glow plug is not energized after the afterglow step. Accordingly, the temperature of the resistance heater is gradually lowered to a low value. However, black smoke may be generated in the combustion chamber when the accelerator is suddenly applied to the engine at a high speed or a high output while the combustion chamber of the engine is cold. Also, in places with low air, such as high altitudes, combustion may worsen and white smoke may be generated in the combustion chamber. For this reason, even after the afterglow step is completed, it is necessary to raise the temperature of the resistance heater again to promote warming in the combustion chamber and to suppress the generation of black smoke and white smoke. Therefore, the glow plug is energized again to raise the temperature of the resistance heater. Such a step is generally called an intermediate temperature rise, an intermediate temperature rise glow, an intermediate temperature rise glow step, or the like. In the conventional intermediate temperature raising glow step, the duty ratio of the voltage waveform applied to the glow plug is calculated based on the voltage value applied from the battery to the glow plug, and the energization to the glow plug is PWM controlled based on this duty ratio. Thus, the temperature of the resistance heater is increased toward a predetermined target temperature (for example, 1250 ° C.). For example, the energization control is described in claim 6 of the patent document 1 and the embodiment. In Patent Document 1, this intermediate temperature raising glow step is called “temporary heating”.

Japanese Patent No. 2880172

However, in the conventional glow plug energization control device, the rise of the temperature at the initial stage of the intermediate temperature increase glow step in which the energization to the glow plug is PWM controlled by the duty ratio based on the voltage value applied from the battery to the glow plug is delayed, It takes time for the resistance heater to reach the target temperature. For this reason, as described above, even if black smoke or white smoke is generated in the combustion chamber, it cannot be immediately suppressed.
As a method for solving such a problem, there can be considered a method in which the resistance heating heater is rapidly heated by continuously energizing the glow plug for a predetermined time in the initial stage of the intermediate temperature raising glow step. However, when the process proceeds to the intermediate temperature raising glow step immediately after the after glow step is completed, the temperature of the resistance heating heater is not sufficiently lowered and is in a relatively high temperature state. When energized, the resistance heater rises far beyond the target temperature, causing problems such as disconnection of the glow plug and reduced durability that makes the glow plug resistance abnormal. .

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a glow plug control device and a glow plug energization control method capable of rapidly raising a resistance heater to a target temperature in an intermediate temperature rise glow step. To do.

  The solution is a glow plug energization control device that controls energization from a battery to a glow plug having a resistance heating heater installed in the engine when the key switch is set to the on position and the start position. After the start-up, after the start-up glow means for stable heating of the resistance heater, and after the end of energization control by the post-start-up glow means, the resistance heater is heated to a target temperature and maintained. And an intermediate temperature rise glow means for controlling energization to the glow plug, the duty ratio of the voltage waveform applied to the glow plug based on a target resistance value corresponding to the target temperature for the resistance heater. Dt1 is calculated, and a first intermediate temperature raising unit that PWM-controls the energization to the glow plug based on the duty ratio Dt1 is provided. An intermediate Atsushi Nobori glow unit, a glow plug energization control apparatus comprising a.

According to the present invention, the glow plug energization control device includes at least a post-starting glow unit and an intermediate temperature raising glow unit.
Of these, the post-start glow means is for stably heating the resistance heater after the engine is started. By such means, the resistance heating heater can be stably heated even after the engine is started, so that warming up of the engine combustion chamber is promoted, diesel knocks are prevented, noise and white smoke are generated, and HC components are discharged. Etc. can be suppressed.
On the other hand, the intermediate temperature raising glow means controls the energization to the glow plug so that the resistance heating heater is raised to the target temperature again and maintained after the end of the energization control by the glow means after starting. It is. As described above, even after the engine is started, black smoke may be generated in the combustion chamber when the accelerator is suddenly swung while the engine is cold and the engine is at a high speed or high output. is there. Also, in places with low air, such as high altitudes, combustion may worsen and white smoke may be generated in the combustion chamber. However, it is possible to suppress the generation of black smoke and white smoke by raising the temperature of the resistance heater and promoting warming in the combustion chamber by the intermediate temperature raising glow means.

However, when the energization to the glow plug is PWM controlled by the duty ratio based on the voltage value applied from the battery to the glow plug, which is a conventional method, the resistance rises because the initial temperature rise is slow as described above. It takes time for the heater to reach the target temperature. For this reason, even if black smoke or white smoke is generated in the combustion chamber, it cannot be immediately suppressed.
On the other hand, the intermediate temperature raising glow means of the present invention calculates the duty ratio Dt1 of the voltage waveform applied to the glow plug based on the target resistance value corresponding to the target temperature for the resistance heating heater, and this duty ratio Dt1. Thus, at least first intermediate temperature raising means for PWM-controlling energization to the glow plug is provided. Since the resistance value of the resistance heater is in a steady state corresponding to the temperature, that is, there is a correlation between the resistance value of the resistance heater and the temperature, the resistance value is based on the target resistance value corresponding to the target temperature. If the duty ratio Dt1 is used, the heater temperature can be raised more accurately toward the target temperature. In addition, by performing PWM control of energization with such a duty ratio Dt1, the resistance heating heater can be rapidly heated as compared with the conventional method. Therefore, even if black smoke or white smoke is generated in the combustion chamber for some reason, it can be immediately suppressed. Also, unlike continuous energization of the glow plug over a certain period of time, the resistance heating heater is prevented from excessively exceeding the target temperature even when the intermediate temperature is raised immediately after the energization control by the glow means after starting. it can. For this reason, disconnection of the glow plug can be prevented, and a decrease in the durability of the glow plug can be suppressed. For example, if the duty ratio Dt1 corresponding to each resistance value is determined in advance, the heater temperature can be controlled by a simple control mode.

  Furthermore, in the above glow plug energization control device, the intermediate temperature raising glow means is based on a voltage value applied from the battery to the glow plug following energization control by the first intermediate temperature raising means. The glow plug energization control device may include a second intermediate temperature raising unit that calculates a duty ratio Dt2 of a voltage waveform applied to the glow plug and performs PWM control of energization to the glow plug based on the duty ratio Dt2.

According to the present invention, the intermediate temperature raising glow means has the second intermediate temperature raising means in addition to the first intermediate temperature raising means described above. The second intermediate temperature raising means calculates the duty ratio Dt2 of the voltage waveform applied to the glow plug based on the voltage value applied from the battery to the glow plug following the energization control by the first intermediate temperature raising means. The energization to the glow plug is PWM controlled by the duty ratio Dt2.
The first intermediate temperature raising means described above is excellent in rapid temperature rise of the resistance heater, but the temperature variation near the target temperature may increase. On the other hand, the second intermediate temperature raising means is inferior to the rapid temperature raising of the resistance heater, but can easily maintain the heater temperature stably at the target temperature. Therefore, the energization control is first performed by the first intermediate temperature raising means, and then the energization control is performed by the second intermediate temperature raising means, thereby enabling rapid temperature rise and stabilizing the heater temperature at the target temperature. Can be maintained.

Furthermore, in the glow plug energization control device according to any one of the above, the first intermediate temperature raising means sets the current resistance value of the resistance heating heater to R, and the resistance heating heater reaches the target temperature. When the resistance value is Ro, the applied voltage to the glow plug is Vb, the error ΔR1 is given by ΔR1 = Ro−R, and the control effective voltage value Vc1 is given by Vc1 = K0 + K1 · ΔR1, the duty ratio Dt1 is A glow plug energization control device having calculation means for calculating according to Dt1 = (Vc1) ² / (Vb) ² is preferable.

According to the present invention, the first intermediate temperature raising means gives the duty ratio when the resistance value error ΔR of the resistance heater is given by ΔR1 = Ro−R and the control effective voltage value Vc1 is given by Vc1 = K0 + K1 · ΔR1. There is a calculation means for calculating Dt1 according to Dt1 = (Vc1) ² / (Vb) ² . By calculating the duty ratio Dt1 and controlling the energization of the glow plug in this way, the resistance heating heater can be raised more accurately toward the target temperature during the energization control by the first intermediate temperature raising means. K0 and K1 are coefficients.

  Another solution is a glow plug energization control method for controlling energization from a battery to a glow plug having a resistance heater installed in an engine when a key switch is set to an on position and a start position. After starting the engine, after the start-up glow step for stable heating of the resistance heater, and after the end of the start-up glow step, the resistance heater is raised to a target temperature and maintained. And an intermediate temperature rise glow step for controlling energization to the glow plug, wherein the duty ratio of the voltage waveform applied to the glow plug is based on a target resistance value corresponding to the target temperature for the resistance heater. Dt1 is calculated, and a first intermediate temperature raising step for PWM-controlling energization to the glow plug based on the duty ratio Dt1. An intermediate heating glow step with a glow plug energization control method comprising a.

According to the present invention, the glow plug energization control method includes at least a post-startup glow step and an intermediate temperature increase glow step.
Of these, in the after-start glow step, the resistance heating heater is stably heated after the engine is started. By such steps, the resistance heating heater can be stably heated even after the engine is started, so that warming up of the combustion chamber of the engine is promoted, generation of diesel knock is prevented, generation of noise and white smoke, generation of HC components, etc. Emissions can be suppressed.
On the other hand, in the intermediate temperature raising glow step, energization of the glow plug is controlled so that the resistance heating heater is raised to the target temperature again and maintained after the completion of the glow step after start-up. As described above, even after the engine is started, black smoke or white smoke may be generated in the combustion chamber. By this intermediate temperature increase glow step, the resistance heating heater is heated to promote warming in the combustion chamber. Thus, generation of black smoke and white smoke can be suppressed.

However, when the energization to the glow plug is PWM controlled by the duty ratio based on the voltage value applied from the battery to the glow plug, which is a conventional method, the resistance rises because the initial temperature rise is slow as described above. It takes time for the heater to reach the target temperature. For this reason, even if black smoke or white smoke is generated in the combustion chamber, it cannot be immediately suppressed.
On the other hand, in the intermediate temperature raising glow step of the present invention, the duty ratio Dt1 of the voltage waveform applied to the glow plug is calculated based on the target resistance value corresponding to the target temperature for the resistance heating heater, and this duty ratio Dt1. To at least a first intermediate temperature raising step for PWM control of energization to the glow plug. Since the resistance value of the resistance heating heater is in a steady state corresponding to the temperature, the heater temperature can be raised to the target temperature more accurately by using the duty ratio Dt1 based on the target resistance value corresponding to the target temperature. . In addition, by performing PWM control of energization with such a duty ratio Dt1, the resistance heating heater can be rapidly heated as compared with the conventional method. Therefore, even if black smoke or white smoke is generated in the combustion chamber for some reason, it can be immediately suppressed. Also, unlike when energizing the glow plug for a certain period of time, the resistance heating heater is prevented from rising far beyond the target temperature even when the intermediate temperature rise glow step is performed immediately after the start of the glow step after starting. it can. For this reason, disconnection of the glow plug can be prevented, and a decrease in the durability of the glow plug can be suppressed. For example, if the duty ratio Dt1 corresponding to each resistance value is determined in advance, the heater temperature can be controlled by a simple control mode.

  Further, in the glow plug energization control method described above, the intermediate temperature raising glow step may be performed based on a voltage value applied to the glow plug from the battery following the first intermediate temperature raising step. A glow plug energization control method including a second intermediate temperature raising step of calculating a duty ratio Dt2 of a voltage waveform applied to the plug and PWM controlling the energization to the glow plug based on the duty ratio Dt2.

According to the present invention, the intermediate temperature raising glow step has a second intermediate temperature raising step in addition to the first intermediate temperature raising step described above. In the second intermediate temperature raising step, following the first intermediate temperature raising step, the duty ratio Dt2 of the voltage waveform applied to the glow plug is calculated based on the voltage value applied from the battery to the glow plug, and this duty is calculated. The energization to the glow plug is PWM controlled by the ratio Dt2.
The first intermediate temperature raising step described above is excellent for rapid temperature rise of the resistance heater, but there may be a large temperature variation near the target temperature. On the other hand, the second intermediate heating step is inferior to the rapid heating of the resistance heater, but it is easy to stably maintain the heater temperature at the target temperature. Therefore, by first performing the first intermediate temperature raising step and subsequently performing the second intermediate temperature raising step, rapid temperature rise is possible and the heater temperature can be stably maintained at the target temperature.

Furthermore, in the glow plug energization control method according to any one of the above, in the first intermediate heating step, the current resistance value of the resistance heater is R, and the resistance heater is at the target temperature. When the resistance value is Ro, the applied voltage to the glow plug is Vb, the error ΔR1 is given by ΔR1 = Ro−R, and the control effective voltage value Vc1 is given by V1c = K0 + K1 · ΔR1, the duty ratio Dt1 is A glow plug energization control method having a calculation step of calculating according to Dt1 = (Vc1) ² / (Vb) ^{2 is} preferable.

According to the present invention, in the first intermediate heating step, when the resistance value error ΔR1 of the resistance heater is given by ΔR1 = Ro−R and the control effective voltage value Vc1 is given by Vc1 = K0 + K1 · ΔR1, the duty ratio A calculation step of calculating Dt1 according to Dt1 = (Vc1) ² / (Vb) ² . If the duty ratio Dt1 is calculated in this way and the energization to the glow plug is controlled, the resistance heating heater can be raised more accurately toward the target temperature during the first intermediate heating step. K0 and K1 are coefficients.

(Embodiment)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the glow plug 1 that is energized and controlled by the glow plug energization control device 101 of the present invention will be described. FIG. 1 shows a cross-sectional view of the glow plug 1. This glow plug 1 includes a cylindrical metal shell 4 and a rod-shaped ceramic heater (in the shape of the metal shell 4 protruding in the shape of the axis O in the direction of the axis O so as to protrude its own tip). In order to energize the ceramic heater 2, a resistance heating heater 2) and a metal shaft 6 inserted in the direction of the axis O inside the rear end of the metal shell 4 (upward in the drawing) are provided.

Inside the metal shell 4, the metal shaft 6 is disposed in an insulated state from the metal shell 4. A ceramic ring 31 is disposed between the outer peripheral surface of the rear end side of the metal shaft 6 and the inner peripheral surface of the metal shell 4, and a glass filling layer 32 is formed on the rear side thereof. The metal shaft 6 is provided with irregularities by knurling or the like on the outer peripheral surface that comes into contact with the glass filling layer 32 (shown by shading in the figure). Further, the rear end portion of the metal shaft 6 extends from the rear side of the metal shell 4, and the terminal metal fitting 7 is fitted into the extended portion via an insulating bush 8. The terminal fitting 7 is fixed in a conductive state to the outer peripheral surface of the metal shaft 6 by a caulking portion 9 in the circumferential direction.
Further, the glow plug 1 has a cylindrical heater holding ring 3 on the tip side thereof. The heater holding ring 3 holds the ceramic heater 2 in an interference-fitted state inside the ceramic heater 2 such that the tip 2s protrudes in the direction of the axis O. On the other hand, the heater holding ring 3 is held in a tightly fitted state inside the front end of the metal shell 4.

  The ceramic heater 2 is configured as a rod-shaped ceramic heater element in which a resistance heating element 11 is embedded in a ceramic base 13 made of an insulating ceramic. The resistance heating element 11 is embedded in the tip end portion in the axis O direction with respect to the ceramic heater 2. Further, current-carrying path portions 12 and 12 whose front ends are electrically connected to the resistance heating element 11 and whose rear ends are exposed to the rear end surface 2r of the ceramic heater 2 are embedded in the direction of the axis O. And the metal electrode extraction members 26 and 27 are electrically connected to the exposed region on the rear end face 2r of the energization path portions 12 and 12 through the metal layer. Furthermore, the electrode extraction member 26 is electrically connected to the metal shaft 6 via the lead portion 17, while the electrode extraction member 27 is electrically connected to the heater holding ring 3 via the lead portion 16. .

  A ceramic resistor unit 10 made of a conductive ceramic is embedded in the ceramic base 13 of the ceramic heater 2. The ceramic resistor unit 10 is made of a first conductive ceramic, and a first resistor part 11a disposed at the tip of the ceramic heater 2 and an axis O of the ceramic heater 2 on the rear side of the first resistor part 11a. A pair of second conductive ceramics that are made of a second conductive ceramic that has a distal end portion joined to both ends of the first resistor portion 11a and has a lower resistivity than the first conductive ceramic. It has resistor parts 11b and 11b. The first resistor portion 11a constitutes a resistance heating element, and the second resistor portions 11b and 11b constitute an energization path portion.

  The glow plug 1 is attached to a mounting hole formed in an engine block of an internal combustion engine such as a diesel engine by a screw portion 5 provided on the outer peripheral surface of the metal shell 4. A tip portion serving as a heat generating portion of the ceramic heater 2 is positioned in a vortex chamber communicating with the combustion chamber of the engine.

Next, the glow plug energization control device 101 according to the present invention will be described. FIG. 2 is a block diagram showing an electrical configuration of the glow plug energization control apparatus 101 of the present invention.
The main control unit 111 receives a stable operating voltage for signal processing via the power supply circuit 103. The power supply circuit 103 receives power from the battery BT via the key switch KSW and the terminal 101B. Therefore, when the key switch KSW is set to the on position and the start position, power is supplied to the power supply circuit 103 and the main control unit 111 operates. On the other hand, when the key switch KSW is turned OFF, power supply to the power supply circuit 103 is interrupted, and the main control unit 111 stops operating.

  The power of the battery BT is supplied to n switching elements 1051 to 105n via the terminal 101F. Each of the switching elements 1051 to 105n is configured by an FET in this embodiment, and the voltage of the battery BT is supplied to the drain of the FET. The source of each FET is connected to a plurality (n) of glow plugs GP1 to GPn via the terminals 101G1 to 101Gn. In addition, a switching signal from the main control unit 111 is input to the gate of each FET, and energization to each glow plug GP1 to GPn is turned ON / OFF. Further, the FETs constituting the switching elements 1051 to 105n are specifically composed of FETs with a current detection function (PROFET (registered trademark) manufactured by Infineon Technologies AG), from which current signals are sent to the main control unit 111. Is output.

The main control unit 111 receives a voltage applied from the battery BT to each of the glow plugs GP1 to GPn and an energization current to each of the glow plugs GP1 to GPn. The applied voltage to the glow plugs GP1 to GPn and the magnitude of the energization current to the glow plugs GP1 to GPn input to the main control unit 111 are digitized by an A / D converter (not shown).
The main control unit 111 is capable of communicating with an engine control unit 201 (Engine Control Unit: hereinafter also referred to as an ECU) configured by a microcomputer via an interface. The main control unit 111 is configured to be able to input a drive signal for the alternator 211.

Next, energization control of the glow plug 1 by the glow plug energization control device 101 will be described with reference to the flowcharts shown in FIGS.
In this energization control, the following operations are basically performed. That is, when the operator sets the key switch KSW to the ON position, the pre-glow step controlled by the pre-glow means is entered. That is, the voltage of the battery BT is directly applied to the glow plug 1, and the ceramic heater 2 is heated in a short time to reach a target temperature (for example, 1250 ° C.).
Thereafter, the process proceeds to a transition glow step controlled by the transition glow means. That is, the energization to the glow plug 1 is PWM controlled based on the voltage applied to the glow plug 1 to suppress the temperature drop of the ceramic heater 2.

If the operator sets the key switch KSW to the start position during the transition glow step, the process proceeds to the cranking glow step controlled by the cranking glow means. That is, the energization to the glow plug 1 is PWM-controlled based on the voltage applied to the glow plug 1 to suppress the temperature drop of the ceramic heater 2 and improve the engine startability.
After the engine is started, the process proceeds to a post-start glow step controlled by the post-start glow means. That is, on the basis of the voltage applied to the glow plug 1, the energization to the glow plug 1 is PWM controlled for a predetermined time (for example, 80 seconds), and the ceramic heater 2 is set to a target temperature (for example, 1250 ° C.) and maintained.

  When a signal for performing an intermediate temperature increase is input to the glow plug energization control device 101, for example, black smoke or white smoke is generated in the combustion chamber after the glow step after the start is completed, The controlled intermediate warming glow step begins. That is, based on the resistance value of the glow plug 1 (ceramic heater 2), the energization to the glow plug 1 is PWM-controlled, and the ceramic heater 2 is rapidly heated to a target temperature (for example, 1250 ° C.) (first Intermediate heating step). Subsequently, on the basis of the voltage applied to the glow plug 1, the energization to the glow plug 1 is PWM-controlled, and the ceramic heater 2 is set to a target temperature (for example, 1250 ° C.) and maintained (second intermediate temperature rise). Step).

  When the key switch KSW is turned on, the main control unit 111 is turned on. Specifically, the battery BT is driven to the main control unit 111 via the key switch KSW, the terminal 101B, and the power supply circuit 103. A voltage is applied, and the main control unit 111 starts operating in a predetermined procedure. Then, as shown in FIG. 3, first, in step S1, the program of the main control unit 111 is initialized. For example, the integrated power amount Gw to the glow plug 1 is set to Gw = 0. Further, a pre-glow flag (a flag indicating that the pre-glow step is being performed) is set. On the other hand, other flags, for example, a pre-glow end flag (a flag indicating that the pre-glow step has ended), a start signal flag (a flag indicating that the key switch KSW is at the start position), and after the start Glow in progress flag (a flag indicating that a post-starting glow step is in progress), a post-starting glow end flag (a flag indicating that the post-starting glow step has been completed), an intermediate temperature increase signal flag (intermediate temperature increase A flag indicating that a signal to be performed is input), a first intermediate temperature increase end flag (a flag indicating that the first intermediate temperature increase step is completed), and the like are each cleared.

  Next, in step S2, a voltage value Vb applied to the glow plug 1 from the battery BT and a current value flowing through the glow plug 1 through each of the switching elements 1051 to 105n are captured. Then, the current resistance value R of each ceramic heater 2 is calculated from the voltage value Vb and the current value.

  Next, in step S3, start signal input processing is performed. That is, the process proceeds to a subroutine shown in FIG. Specifically, first, in step S31, it is determined that the pre-glow step has been completed, the post-start-up glow step is not being performed, and the intermediate temperature raising glow step is not being performed. That is, it is determined whether the pre-glow end flag is set, the post-start glow flag is cleared, and the intermediate temperature raising signal flag is cleared. Here, in the case of YES, the process proceeds to step S32. In other words, if the transition glow step is being performed, the cranking glow step is being performed, or if the intermediate temperature raising glow step is not being performed after the start-up glow step, the process proceeds to step S32. On the other hand, in the case of NO, the process directly returns to the main routine. In other words, in the case of the pre-glow step, the post-start-up glow step, or the intermediate temperature rise glow step, the process directly returns to the main routine.

  If the process proceeds to step S32, a start signal is captured. Then, the process proceeds to step S33, and it is determined whether or not the input of the start signal is continuously on for 0.1 seconds, specifically, whether or not the input of the start signal is continuously on for 8 cycles. That is, it is determined whether or not the key switch KSW is at the start position. The reason why the input is continuously viewed for 0.1 sec is to eliminate the case where an erroneous start signal due to noise or the like is input. If YES, the process proceeds to step S34, and a start signal flag is set. Then, the process returns to the main routine. On the other hand, if NO, the process proceeds to step S35. In step S35, it is determined whether or not the input of the start signal is OFF for 0.1 seconds, specifically, whether or not the input of the start signal is OFF for 8 consecutive cycles. That is, it is determined whether or not the key switch KSW is not at the start position. If YES, the process proceeds to step S36 to clear the start signal flag. On the other hand, in the case of NO, the process directly returns to the main routine.

  Next, in step S4 of the main routine of FIG. 3, an intermediate temperature rise signal input process is performed. That is, the process proceeds to a subroutine shown in FIG. Specifically, first, in step S41, it is determined whether or not the post-start glow step has ended. That is, it is determined whether the after-start glow end flag is set. Here, in the case of NO, the process proceeds to step S44, and the intermediate temperature increase signal flag is cleared. Then, the process returns to the main routine. On the other hand, if YES, the process proceeds to step S42. In step S42, it is determined whether an intermediate temperature rise signal is input. Here, in the case of YES, the process proceeds to step 43, and the intermediate temperature rise signal flag is set. Then, the process returns to the main routine. On the other hand, if NO, the process proceeds to step S44 to clear the intermediate temperature increase flag. Then, the process returns to the main routine.

Next, in step S5 of the main routine in FIG. 3, the duty ratio Dh referred to during the transition glow step, the duty ratio Dk referred to during the cranking glow step, and the duty ratio Da referred to during the glow step after starting. The duty ratio Dt2 to be referred to during the second intermediate temperature raising step is calculated.
Specifically, for the transition glow step, the duty ratio Dh of the voltage waveform applied to the glow plug 1 is calculated based on the voltage value applied to the glow plug 1. For example, it may be prepared in the form of a table or function indicating the relationship between the voltage value applied to the glow plug 1 and the duty ratio Dh, and the duty ratio Dh may be determined with reference to this table.
Similarly, regarding the cranking glow step, the duty ratio Dk of the voltage waveform applied to the glow plug 1 is calculated based on the voltage value applied to the glow plug 1. For example, it may be prepared in the form of a table or function indicating the relationship between the voltage value applied to the glow plug 1 and the duty ratio Dk, and the duty ratio Dh may be determined with reference to this table. The duty ratio Dk referred to during the cranking glow step is such that the voltage value applied to the glow plug 1 during the transition glow step is the same as the voltage value applied to the glow plug 1 during the cranking glow step. Assuming that there is a value, the value is larger than the virtual duty ratio Dhh referred to in the transition glow step.

Similarly, for the post-start glow step, the duty ratio Da of the voltage waveform applied to the glow plug 1 is calculated based on the voltage value applied to the glow plug 1. For example, it may be prepared in the form of a table or function indicating the relationship between the voltage value applied to the glow plug 1 and the duty ratio Da, and the duty ratio Da may be determined with reference to this table.
Similarly, also for the second intermediate temperature raising step, the duty ratio Dt2 of the voltage waveform applied to the glow plug 1 is calculated based on the voltage value applied to the glow plug 1. For example, it may be prepared in the form of a table or function indicating the relationship between the voltage value applied to the glow plug 1 and the duty ratio Dt2, and the duty ratio Dt2 may be determined with reference to this table.

Next, in step S6, a duty ratio Dt1 referred to during the first intermediate temperature raising step is calculated. That is, the process proceeds to a subroutine shown in FIG. Here, first, in step S61, the error ΔR1 of the resistance value of the ceramic heater 2 is calculated. Specifically, the current resistance value of the ceramic heater 2 is R, the resistance value of each ceramic heater 2 stored during the glow step after startup is Ro, and an error ΔR1 of the resistance value is given by ΔR1 = Ro−R. Next, it progresses to step S62 and the control effective voltage value Vc1 is calculated. Specifically, the control effective voltage value Vc1 is given by Vc1 = K0 + K1 · ΔR1. K0 and K1 are constants, but K0 and K1> 0. Then, it progresses to step S63 and calculates duty ratio Dt1. Specifically, the duty ratio Dt1 is calculated according to Dt1 = (Vc1) ² / (Vb) ² . Vb is the voltage value (glow voltage) acquired in step S2. Then, the process returns to the main routine.

Next, in step S7 of the main routine of FIG. 3, it is determined whether or not cranking is in progress. That is, it is determined whether the start signal flag is set. Here, in the case of YES, the process proceeds to step S8. On the other hand, if NO, the process proceeds to step S9.
When the process proceeds to step S8, cranking glow processing is performed. That is, the process proceeds to a subroutine shown in FIG. Here, cranking energization is turned on in step S81. That is, the energization to the glow plug 1 is PWM controlled based on the duty ratio Dk calculated in step S5. Thereafter, the process returns to the main routine.

Next, when the process proceeds from step S7 to step S9 in the main routine of FIG. 3, it is determined whether or not the alternator is activated.
Here, in the case of YES, the process proceeds to the glow process after start in step S10. That is, the process proceeds to a subroutine shown in FIG. Here, first, in step S101, it is determined whether or not a predetermined time (for example, 80 seconds) of the after-start glow step has elapsed. Specifically, the determination is made based on whether or not the counter to be counted up in step S102 described later has reached a predetermined value. Here, in the case of NO, the process proceeds to step S102, where after-starting glow energization is turned on, and the after-starting glow flag is set. In addition, the time required for the after-start glow step is counted up as described above. The glow energization after start-up performs PWM control of energization to the glow plug 1 based on the duty ratio Da calculated in step S5, and if the temperature of the ceramic heater 2 has not yet reached the target temperature, the target temperature and If the target temperature has already been reached, this temperature is maintained.

After step S102, the process proceeds to step S103, where it is determined whether it is time to store the resistance value of the ceramic heater 2 (for example, 5 seconds after the start of the glow step after starting). Here, in the case of NO, that is, when the memory time is not yet reached or when the memory time has already passed, the process returns to the main routine as it is. On the other hand, if YES, that is, if it is the memory time, the process proceeds to step S104, and the resistance value R of each ceramic heater 2 at that time is stored in the memory as the resistance value Ro. Thereafter, the process returns to the main routine.
On the other hand, if YES in step S101, the process proceeds to step S105. Then, the glow energization after starting is turned off, the after-starting glow flag is cleared, and further, the after-starting glow end flag is set. Thereafter, the process returns to the main routine.

  Next, the case of NO in step S9 of the main routine of FIG. 3 will be described. In this case, the process proceeds to the pre-glow process in step S11. That is, the process proceeds to a subroutine shown in FIG. Here, first, in step S111, it is determined whether or not a pre-glow step is in progress. That is, it is determined whether the pre-glow flag is set. Here, in the case of YES, the process proceeds to step S112, and the electric energy (Gw1) input to the glow plug 1 during one cycle is calculated. Next, it progresses to step S113 and the integral electric energy (Gw) of the glow plug 1 is calculated. That is, the newly added power amount Gw1 is added to the previous integrated power amount Gw to obtain a new integrated power amount Gw.

Next, in step S114, it is determined whether or not the integrated power amount Gw has exceeded the target input amount corresponding to the target temperature in the pre-glow step. Here, in the case of YES, the process proceeds to step S115 and the pre-glow energization is turned off. Also, the pre-glow flag is cleared, while the pre-glow end flag is set. Thereafter, the process returns to the main routine. On the other hand, if NO in step S114, the process proceeds to step S116, and pre-glow energization is turned on. Specifically, continuous energization is performed to the glow plug 1. Thereafter, the process returns to the main routine.
If NO in step S111, the process returns to the main routine as it is.

  Next, in step S12 of the main routine of FIG. 3, a transition glow process is performed. That is, the process proceeds to a subroutine shown in FIG. Here, first, in step S121, it is determined whether or not it is during a cranking step or whether or not it is in a post-startup glow step. That is, it is determined whether the start signal flag is set or the after-start glow flag is set. Here, in the case of YES, the process proceeds to step S127, and the transition glow energization is turned off. Then, the process returns to the main routine. On the other hand, in the case of NO, the process proceeds to step S122, and it is determined whether or not a predetermined time of the transition glow step has elapsed. Specifically, it is determined whether or not a counter to be counted up in step S124 described later has reached a predetermined value. Here, in the case of YES, the process proceeds to step S126, and the transition glow energization is turned off. Then, the process returns to the main routine. On the other hand, if NO, the process proceeds to step S123 to determine whether or not the pre-glow step is completed. That is, it is determined whether the pre-glow end flag is set. Here, in the case of NO, the process proceeds to step S125, and the transition glow energization is turned off. Then, the process returns to the main routine. On the other hand, if YES in step S123, the process proceeds to step S124 to turn on the transition glow energization. In this transition glow energization, the energization to the glow plug 1 is PWM-controlled based on the duty ratio Dh calculated in step S5 to suppress the temperature drop of the ceramic heater 2. In step S124, as described above, the predetermined time of the transition glow step is counted up. Thereafter, the process returns to the main routine.

  Next, returning to the main routine of FIG. 3, the process proceeds to step S13 to determine whether or not the intermediate temperature raising glow step is in progress. That is, it is determined whether the intermediate temperature rise signal flag is set. Here, in the case of YES, the process proceeds to step S14, and the first intermediate temperature raising process is performed. That is, the process proceeds to a subroutine shown in FIG. Here, first, in step S141, it is determined whether or not a predetermined time (2 seconds in this embodiment) of the first intermediate temperature raising step has elapsed. Specifically, it is determined whether or not a counter to be counted up in step S142 described later has reached a predetermined value. Here, in the case of NO, the process proceeds to step S142, and the first intermediate temperature increase energization is turned on. In the first intermediate temperature increase energization, the ceramic heater 2 is rapidly heated by PWM control of the energization to the glow plug 1 based on the duty ratio Dt1 calculated in step S6. In step S142, as described above, the predetermined time of the first intermediate heating step is counted up. Thereafter, the process returns to the main routine. On the other hand, if YES in step S141, the process proceeds to step S143 to turn off the first intermediate temperature increase energization and set the first intermediate temperature increase end flag. Thereafter, the process returns to the main routine.

Next, the process proceeds to step S15 of the main routine of FIG. 3, and it is determined whether or not the first intermediate temperature increase process (first intermediate temperature increase step) has been completed. That is, it is determined whether the first intermediate temperature increase end flag is set. Here, in the case of YES, the process proceeds to step S16, and the second intermediate temperature raising process is performed. That is, the process proceeds to a subroutine shown in FIG. Here, in step S161, the second intermediate temperature increase energization is turned on. In the second intermediate temperature increase energization, the energization to the glow plug 1 is PWM-controlled based on the duty ratio Dt2 calculated in step S5 to maintain the ceramic heater 2 at the target temperature in the intermediate temperature increase glow step. Thereafter, the process returns to the main routine and proceeds to step S17.
If NO in step S13, the process proceeds directly to step S17. Similarly, if NO in step S15, the process proceeds to step S17.

In step S17, it is determined whether 12.5 ms has elapsed. Here, in the case of YES, the process returns to step S2. On the other hand, if NO, step S17 is repeated until this time has elapsed.
The glow plug energization control device 101 of the present invention performs the energization control described above.

(Example 1)
Next, specific examples will be described. In this embodiment, after the operator turns the key switch KSW to the on position, after a while, that is, after the ceramic heater 2 is sufficiently heated, the key switch KSW is used as the start position to start the engine. Thereafter, after a sufficient time has elapsed, that is, after the temperature of the ceramic heater 2 has sufficiently decreased, the energization control of the glow plug energization control device 101 when a signal for intermediate temperature rise is input for some reason. explain.

  FIG. 13 shows the temperature change of the glow plug 1 when the glow plug energization control device 101 of the present invention is used. In this example, the glow plug 1 was mounted in a test plug hole formed in a block made of carbon steel, and a thermocouple was brought into contact with the outer end of the ceramic heater 2 to measure the temperature of the ceramic heater 2. In this desk test, since a temperature of 400 ° C. or lower could not be measured, a temperature change at 400 ° C. or higher is shown. In addition, since all the desktop experiments were conducted in a windless state, the heater temperatures in the cranking glow step, the post-starting glow step, and the intermediate temperature raising glow step were different from those actually used in the engine. ing. That is, when actually used in the engine, the reached temperatures in the cranking glow step, the post-startup glow step, and the intermediate temperature raising glow step are the reached temperatures of the pre-glow step and the transition glow step, respectively (1250 in this embodiment). C)).

(Pre-glow step)
First, when the operator sets the key switch KSW to the on position, the pre-glow step is entered, and the ceramic heater 2 is controlled at the target temperature in the pre-glow step (1250 ° C. in this embodiment) by energization control to the glow plug 1 by the pre-glow means. (See FIG. 13).
Describing along the above-described flowchart, when the key switch KSW is set to the ON position, the process proceeds to step S1 (see FIG. 3), the glow plug energization control device 101 is initialized, the pre-glow flag is set, Other flags are cleared. Subsequently, the process proceeds to step S2. At this stage, since the glow plug 1 is not yet energized, the resistance value R is not calculated. Next, the process proceeds to a subroutine of step S3 (see FIG. 4). In step S31, since the pre-glow step is currently in progress and the pre-glow step has not ended yet (because the pre-glow end flag has been cleared), it is determined as NO. Therefore, the process returns to the main routine as it is. Next, the process proceeds to a subroutine of step S4 (see FIG. 5). In step S41, since the after-start glow step has not ended yet (since the after-start glow end flag has been cleared), it is determined as NO and the process proceeds to step S44. Then, the intermediate temperature increase signal flag is continuously cleared. Thereafter, the process returns to the main routine. Next, the process proceeds to step S5 (see FIG. 3). At this stage, since the glow plug 1 is not yet energized, the respective duty ratios Dh, Dk, Da, Dt2 are not calculated. Next, the process proceeds to a subroutine of step S6 (see FIG. 6). At this stage, since the target resistance value Ro is not yet stored, the duty ratio Dt1 is not calculated.

  Next, the process proceeds to step S7 of the main routine (see FIG. 3). In step S7, since cranking is not in progress (since the start signal flag is cleared), it is determined as NO and the process proceeds to step S9. In step S9, since the alternator is not yet activated, it is determined as NO and the process proceeds to a subroutine of step S11 (see FIG. 9). In step S111, since the pre-glow step is being performed (because the pre-glow flag is set), YES is determined, and the process proceeds to step S112. In step S112, the glow plug 1 is not yet energized at this stage, and the power amount GW1 = 0 is set. Then, the process proceeds to step S113. In step S113, since the initial value of the integrated power amount Gw is 0 and the input power amount Gw1 is also 0, Gw = 0. Subsequently, in step S114, since the integrated power Gw has not reached the target input amount, it is determined NO and the process proceeds to step S116. Then, pre-glow energization is turned on. That is, continuous energization is performed from the battery BT to the glow plug 1 in order to rapidly raise the ceramic heater 2. Thereafter, the process returns to the main routine.

  Next, the process proceeds to a subroutine of step S12 (see FIG. 10). In step S121, since it is not during cranking (the start signal flag is cleared) and it is not during the after-start glow step (because the after-start glow flag is also cleared), it is determined as NO, and the process proceeds to step S122. In step S122, since it is not a transition glow step yet and the predetermined time of the transition glow step has not elapsed, it is determined NO and the process proceeds to step S123. In step S123, since the pre-glow step is currently in progress and the pre-glow step has not ended yet (because the pre-glow end flag has been cleared), it is determined as NO and the process proceeds to step S125. Then, the transition glow energization is continuously turned off. Thereafter, the process returns to the main routine and proceeds to step S13 (see FIG. 3). Next, in step S13, since the intermediate temperature increase glow step is not yet performed (because the intermediate temperature increase signal flag is cleared), it is determined NO and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

  Next, in step S2, the voltage value Vb applied to the glow plug 1 and the current value flowing through the glow plug 1 are taken in, and the current resistance value R of the ceramic heater 2 is calculated. Subsequently, the process proceeds to step S3, but returns to the main routine through step S31 as in the previous cycle (see FIG. 4). Next, the process proceeds to step S4. Similar to the previous cycle, the process returns to the main routine through steps S41 and S44 (see FIG. 5). Next, in step S5 (see FIG. 3), the respective duty ratios Dh, Dk, Da, Dt2 are calculated based on the voltage value Vb captured in step S2. During the pre-glow step, these duty ratios are calculated. The duty ratios Dh, Dk, Da, and Dt2 are not referred to. Next, the process proceeds to a subroutine of step S6 (see FIG. 6), but the duty ratio Dt1 is not calculated as in the previous cycle.

  Next, the process proceeds to step S7 (see FIG. 3). In step S7, as in the previous cycle, since cranking is not in progress, NO is determined, and the process proceeds to step S9. Also in step S9, as in the previous cycle, since the alternator is not activated, it is determined NO and the process proceeds to a subroutine of step S11 (see FIG. 9). In step S111, as described above, since it is currently in the pre-glow step, it is determined YES and the process proceeds to step S112. In step S112, the amount of power GW1 input to the glow plug 1 during one cycle is calculated. Then, it progresses to step S113 and integrated electric energy Gw is calculated. That is, the newly input power amount Gw1 is added to the integrated power amount Gw (0 in this case) one cycle before to obtain a new integrated power amount Gw. Next, in step S114, since the integrated power amount Gw has not yet reached the target input amount, it is determined NO and the process proceeds to step S116. Then, the pre-glow energization is continuously turned on. Thereafter, the process returns to the main routine.

  Next, the process proceeds to a subroutine of step S12 (see FIG. 10), but returns to the main routine through steps S121, S122, S123, and S125 as in the previous cycle. Next, in step S13 (see FIG. 3), as in the previous cycle, since the intermediate temperature increase glow step is not being performed, NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

  Thereafter, the above cycle is repeated for a while until the integrated power amount Gw exceeds the target input amount (see step S114 in FIG. 9). If the integrated power amount Gw exceeds the target input amount, YES is determined in step S114 (see FIG. 9), the process proceeds to step S115, and the pre-glow energization is turned off. Also, the pre-glow flag is cleared, while the pre-glow end flag is set. At this time, the temperature of the ceramic heater 2 has reached the target temperature (1250 ° C.) as shown in FIG. The time required to reach this target temperature is about 3 seconds. Thereafter, the process returns to the main routine and proceeds to a subroutine of step S12 (see FIG. 10). In step S121, as in the previous cycle, neither cranking nor a post-start glow step is in effect, so it is determined as NO and the process proceeds to step S122. Even in step S122, as in the previous cycle, since the predetermined time of the transition glow step has not yet elapsed, NO is determined, and the process proceeds to step S123. In step S123, unlike the above-described cycle, since the pre-glow step has been completed (because the pre-glow end flag has been set), YES is determined, and the process proceeds to step S124.

(Transition glow step)
Next, in step S124, the transition glow energization is turned on. That is, here, the pre-glow step shifts to the transition glow step. In this transition glow step, as shown in FIG. 13, during this step, the ceramic heater 2 is maintained at the target temperature in the transition glow step (1250 ° C. in the present embodiment) to prevent temperature drop. As described above, this transition glow energization is PWM energization to the glow plug 1 based on the duty ratio Dh. Thereafter, the process returns to the main routine and proceeds to step S13 (see FIG. 3). In step S13, as in the previous cycle, since the intermediate temperature increase glow step is not being performed, NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

  Next, in step S2, the current resistance value R of the ceramic heater 2 is calculated as in the previous cycle. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 4). In step S31, the pre-glow step is completed (the pre-glow end flag is set), not the post-starting glow step (the post-starting glowing flag is cleared), and not the intermediate temperature rising glow step (intermediate) Since the temperature raising signal flag is cleared), unlike the above cycle, it is determined as YES and the process proceeds to step S32. Then, after the start signal is captured in step S32, the process proceeds to step S33. However, since the operator has not yet set the key switch KSW to the start position at this stage, there is no continuous start signal input and it is determined as NO. Then, the process proceeds to step S35. In step S35, since the input of the start signal has not been turned off for 8 consecutive cycles at this stage, it is determined as NO. Since the start signal flag is cleared in step S1, the clear state is maintained. Thereafter, the process returns to the main routine and proceeds to step S4 (see FIG. 3), but returns to the main routine through steps S41 and S44 as in the previous cycle (see FIG. 5). Next, it progresses to step S5 (refer FIG. 3), and each duty ratio Dh, Dk, Da, Dt2 is calculated. However, during this transition glow step, the duty ratios Dk, Da, Dt2 other than the duty ratio Dh related to this step are not referred to. Next, the process proceeds to a subroutine of step S6 (see FIG. 6), but the duty ratio Dt1 is not calculated as in the previous cycle.

  Next, the process proceeds to step S7 (see FIG. 3). In step S7, as in the previous cycle, since cranking is not in progress, NO is determined, and the process proceeds to step S9. Also in step S9, as in the previous cycle, since the alternator is not activated, it is determined NO and the process proceeds to a subroutine of step S11 (see FIG. 9). In step S111, since the pre-glow step has already been completed (because the pre-glow flag is cleared), unlike the above cycle, NO is determined, and the process returns to the main routine and proceeds to step S12.

  In the subroutine of step S12 (see FIG. 10), in step S121, as in the previous cycle, neither cranking nor the post-start glow step is determined, so NO is determined, and the process proceeds to step S122. In step S122, since the predetermined time of the transition glow step has not yet elapsed, NO is determined, and the process proceeds to step S123. In step S123, as in the previous cycle, since the pre-glow step has ended, it is determined YES and the process proceeds to step S124. Subsequently, the transition glow energization is turned on. Thereafter, the process returns to the main routine and proceeds to step S13 (see FIG. 3). In step S13 (see FIG. 3), as in the previous cycle, since the intermediate temperature increase glow step is not being performed, NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

Thereafter, the key switch KSW is continuously set to the start position for 0.1 seconds (see step S33 in FIG. 4) or until a predetermined time of the transition glow step has elapsed (see step S122 in FIG. 10). Repeat the above cycle.
If the predetermined time of the predetermined transition glow step has elapsed without the key switch KSW being continuously at the start position for 0.1 second, YES is determined in step S122 of the subroutine shown in FIG. 10, and the process proceeds to step S126. Then, the transition glow energization is turned off. That is, the transition glow step ends. Thereafter, the process returns to the main routine and proceeds to step S13 (see FIG. 3). In step S13 (see FIG. 3), as in the previous cycle, since the intermediate temperature increase glow step is not being performed, NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

(Cranking Glow Step)
On the other hand, before the predetermined time of the transition glow step elapses (in this embodiment, 2 seconds after the start of the transition glow step), when the key switch KSW is continuously at the start position for 0.1 seconds, In step S33 of the subroutine of step S3 (see FIG. 4), since continuous start signal input is recognized, it is determined YES. Then, the process proceeds to step S34, and the start signal flag is set. That is, here, the transition glow step shifts to the cranking glow step. That is, during the cranking period, the ceramic heater 2 is maintained at the target temperature (1250 ° C. in this embodiment) in the cranking glow step, and the energization to the glow plug 1 is PWM controlled so as to suppress the heater temperature drop. . In addition, since the desktop test which shows a result in FIG. 13 is performed in the windless state, the ultimate temperature of the ceramic heater 2 is as high as 1350 ° C.

  Next, the process proceeds to a subroutine of step S4 (see FIG. 5), but returns to the main routine through steps S41 and S44 as in the previous cycle. Next, in step S5 (see FIG. 3), the respective duty ratios Dh, Dk, Da, Dt2 are calculated. However, during this cranking glow step, the duty ratios Dh, Da, Dt2 other than the duty ratio Dk related to this step are not referred to. Next, the process proceeds to a subroutine of step S6 (see FIG. 6), but the duty ratio Dt1 is not calculated as in the previous cycle.

Next, the process proceeds to step S7 (see FIG. 3). In step S7, unlike the above-described cycle, the cranking is currently being performed and the start signal flag is set, so that it is determined YES. Then, the process proceeds to a subroutine of step S8 (see FIG. 7). In step S81, cranking energization is turned on. As described above, this cranking energization is PWM energization to the glow plug 1 based on the duty ratio Dk.
Thereafter, the process returns to the main routine and proceeds to a subroutine of step S12 (see FIG. 10). In step S121, unlike the above-described cycle, cranking is being performed (since the start signal flag is set), so it is determined YES and the process proceeds to step S127. Then, the transition glow energization is continuously turned off. Thereafter, the process returns to the main routine and proceeds to step S13 (see FIG. 3). In step S13, as in the previous cycle, since the intermediate temperature increase glow step is not being performed, NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

  Next, in step S2, the current resistance value R of the ceramic heater 2 is calculated as in the previous cycle. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 4). In step S31, since the pre-glow step is completed and neither the post-starting glow step nor the intermediate temperature raising step is performed, it is determined YES as in the previous cycle, and the process proceeds to step S32, where the start signal is captured. Next, in step S33, since continuous start signal input is recognized, it is determined YES. Then, the process proceeds to step S34, and the start signal flag is continuously set. After that, cranking ends (no continuous start signal is input) (see step S33 in FIG. 4) until the engine starts and the alternator is activated (see step S9 in FIG. 3). Repeated.

(Glow step after startup)
When the engine is started, the operator returns the key switch KSW from the start position to the on position, and therefore, in step S33 of the subroutine of step S3 (see FIG. 4), start signal input for 0.1 seconds is permitted. If not, NO is determined and YES is determined in step S35. Next, the process proceeds to step S36, and the start signal flag is cleared. That is, here, the cranking glow step shifts to the post-starting glow step. That is, the ceramic heater 2 is set to the target temperature (1250 ° C. in this embodiment) in the glow step after starting, and the energization to the glow plug 1 is PWM controlled so as to maintain this temperature. In addition, since the desktop test which shows a result in FIG. 13 is performed in the windless state, the ultimate temperature of the ceramic heater 2 is as high as about 1400 degreeC.

  Next, the process proceeds to a subroutine of step S4 (see FIG. 5). In step S41, as in the previous cycle, the post-start glow step has not yet ended, so it is determined NO, and the process returns to the main routine through step S44. Next, in step S5 (see FIG. 3), the respective duty ratios Dh, Dk, Da, Dt2 are calculated. However, during this post-start glow step, the duty ratios Dh, Dk, Dt2 other than the duty ratio Da relating to this step are not referred to. Next, the process proceeds to a subroutine of step S6 (see FIG. 6), but the duty ratio Dt1 is not calculated as in the previous cycle.

  Next, in step S7, cranking is no longer being performed and the start signal input flag has already been cleared, so it is determined NO and the process proceeds to step S9 (see FIG. 3). In step S9, unlike the above cycle, since the alternator is activated by starting the engine, it is determined YES and the process proceeds to a subroutine of step S10 (see FIG. 8). In step S101, since the predetermined time (80 seconds in this embodiment) of the glow step after start-up has not yet elapsed, NO is determined, and the process proceeds to step S102. Then, after starting, glow energization is turned on, and a post-starting glow flag is set. As described above, the glow energization after the start is performed based on the duty ratio Da so that the glow plug 1 is energized so as to reach the target temperature when the ceramic heater 2 has not yet reached the target temperature (1250 ° C.). When the PWM control is performed and the target temperature has already been reached, the energization of the glow plug 1 is PWM controlled based on the duty ratio Da so as to maintain this temperature. Thereafter, the process proceeds to step S103, and since it is not yet time to store the resistance value R of the ceramic heater 2, it is determined as NO and the process returns to the main routine.

Next, the process proceeds to a subroutine of step S12 (see FIG. 10). In step S121, since the after-start glow step is in progress (since the after-start glow flag is set), it is determined YES and the process proceeds to step S127. Then, the transition glow energization is continuously turned off. Thereafter, the process returns to the main routine and proceeds to step S13 (see FIG. 3). In step S13, as in the previous cycle, since the intermediate temperature increase glow step is not being performed, NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.
Next, in step S2, the current resistance value R of the ceramic heater 2 is calculated as in the previous cycle.

  Thereafter, until the time to memorize the resistance value R of the ceramic heater 2 (see step S103 in FIG. 8), specifically, in the present embodiment, until 5 seconds have elapsed from the start of the glow step after the start, This cycle is repeated. Then, when 5 seconds have elapsed from the start of the glow step after starting, YES is determined in step S103, and the process proceeds to step S104, where the current resistance value R of each ceramic heater 2 is stored as the resistance value Ro. Thereafter, the process returns to the main routine.

  Thereafter, the above cycle is repeated until a predetermined time of the glow step after the start has elapsed (see step S101 in FIG. 8). When the resistance value Ro is stored, the duty ratio Dt1 is calculated in step S6 (see FIG. 6). However, this duty ratio Dt1 is not referred to during this period. When a predetermined time of the glow step after the start has elapsed, YES is determined in step S101 (see FIG. 8), and the process proceeds to step S105. Then, the glow energization after starting is turned off, and the after-starting glow flag is cleared. Furthermore, a post-start glow end flag is set. Thereby, the after-start glow step ends. Therefore, as shown in FIG. 13, the temperature of the ceramic heater 2 decreases with time.

  Next, after step S10, the process proceeds to step S12 (see FIG. 3). In step S121 of the subroutine of step S12 (see FIG. 10), neither cranking is in progress (the start signal flag is cleared), and since it is not in the post-starting glow step (because the post-starting glowing flag is cleared). ), NO, and the process proceeds to step S122. In step S122, since the transition glow step is completed, it is determined YES, the process proceeds to step S126, and the transition glow energization is continuously turned off. Thereafter, the process returns to the main routine and proceeds to step S13 (see FIG. 3). In step S13, as in the previous cycle, since the intermediate temperature increase glow step is not being performed, NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

  Next, in step S2, the current resistance value R of the ceramic heater 2 is calculated as in the previous cycle. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 4). In step S31, the pre-glow step is completed, and since it is neither the post-starting glow step nor the intermediate temperature raising glow step, it is determined YES, the process proceeds to step S32, and the start signal is captured. Next, in step S33, since continuous start signal input is not recognized, it is determined as NO. Next, it is judged as YES in Step S35, and it progresses to Step S36. Then, the start signal flag is continuously cleared and the process returns to the main routine. Next, the process proceeds to a subroutine of step S4 (see FIG. 5). In step S41, unlike the above-described cycle, the post-start glow step has ended (since the post-start end flag is set), YES. The process proceeds to step S42. In step S42, since the intermediate temperature rise signal has not yet been input, it is determined as NO, the process proceeds to step S44, and the intermediate signal input flag is subsequently cleared.

  Next, in step S5 (see FIG. 3), the respective duty ratios Dh, Dk, Da, Dt2 are calculated, but these duty ratios Dh, Dk, Da, Dt2 are not referred to during this period. Next, the process proceeds to a subroutine of step S6 (see FIG. 6), and the duty ratio Dt1 is calculated. As described above, this duty ratio Dt1 is not referred to during this period. Next, the process proceeds to step S7 (see FIG. 3). In step S7, since cranking is not in progress, it is determined NO and the process proceeds to step 9. In step 9, since the alternator is activated, it is determined YES and the process proceeds to step S10. Thereafter, the above cycle is repeated until an intermediate temperature rise signal is input (see step S42 in FIG. 5).

(Intermediate temperature increase glow step (first intermediate temperature increase step))
When the intermediate temperature raising signal is input, YES is determined in step S42 of the subroutine of step S4 (see FIG. 5), and the process proceeds to step S43. Then, an intermediate temperature rise signal flag is set. That is, the intermediate temperature raising glow step starts from here. Specifically, first, the first intermediate heating step is performed for a predetermined time (2 seconds in this embodiment), and the ceramic heater 2 is directed toward the target temperature (1250 ° C. in this embodiment) in the intermediate heating step. The energization to the glow plug 1 is PWM controlled so as to rise. Subsequently, a second intermediate temperature raising step is performed, and the energization to the glow plug 1 is PWM controlled so that the ceramic heater 2 maintains this target temperature. In addition, since the desktop test which shows a result in FIG. 13 is performed in the windless state, the ultimate temperature of the ceramic heater 2 is as high as about 1400 degreeC.

  Next, returning to the main routine, the process proceeds to step S5 (see FIG. 3), and the respective duty ratios Dh, Dk, Da, Dt2 are calculated. During this first intermediate temperature raising step, these duty ratios are calculated. Dh, Dk, Da, and Dt2 are not referenced. Next, the process proceeds to a subroutine of step S6 (see FIG. 6). In step S61, since the resistance value Ro is already stored, the error ΔR1 of the resistance value is calculated from the difference from the current resistance value R of the ceramic heater 2 using this. Thereafter, the process proceeds to step S62, and the control effective voltage value Vc1 is calculated. Furthermore, it progresses to step S63 and calculates the duty ratio Dt1 referred in this 1st intermediate | middle temperature rising step. Thereafter, the process returns to the main routine. Next, it progresses to step S7 (refer FIG. 3), and since it is not in cranking, it is judged NO. Thereafter, the process proceeds to step S9, where the alternator is activated, and it is determined YES. Next, the process proceeds to a subroutine of step S10 (see FIG. 8), but returns to the main routine through steps S101 and S105 as in the previous cycle. Next, the process proceeds to a subroutine of step S12 (see FIG. 10), but returns to the main routine through steps S121, S122, and S126 as in the previous cycle.

  Next, the process proceeds to step S13 (see FIG. 3). In step S13, unlike the above cycle, since the intermediate temperature increase glow step is being performed (because the intermediate temperature increase signal flag is set), YES is determined, and the process proceeds to step S14. In the subroutine of step S14 (see FIG. 11), in step S141, since the predetermined time (2 seconds in the present embodiment) of the first intermediate heating step has not yet elapsed, it is determined NO and the process proceeds to step S142. Then, the first intermediate temperature increase energization is turned on. As described above, in the first intermediate temperature increase energization, the ceramic heater 2 is rapidly heated by PWM-controlling the energization to the glow plug 1 based on the duty ratio Dt1 calculated in step S6. Next, the process returns to the main routine and proceeds to step S15 (see FIG. 3). In step S15, since the first intermediate temperature increase step has not been completed yet (because the first intermediate temperature increase end flag is cleared), it is determined as NO and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2.

  Next, in step S2, the current resistance value R of the ceramic heater 2 is calculated as in the previous cycle. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 4). In step S31, unlike the above cycle, since the intermediate temperature increase glow step is in progress (because the intermediate temperature increase signal flag is set), it is determined as NO and the process directly returns to the main routine. Next, the process proceeds to a subroutine of step S4 (see FIG. 5), and in step S41, since the after-start glow step is completed, it is determined YES and the process proceeds to step S42. In step S42, since the intermediate temperature increase signal is still input, it is determined YES, the process proceeds to step S43, and the intermediate temperature increase signal flag is continuously set. Thereafter, the above cycle is repeated until a predetermined time of the first intermediate heating step elapses (see step S141 in FIG. 11).

(Intermediate temperature increase glow step (second intermediate temperature increase step))
If the predetermined time of the first intermediate heating step has elapsed, YES is determined in step S141 of the subroutine of step S14 (see FIG. 11), and the process proceeds to step S143. Then, the first intermediate temperature increase energization is turned off. In addition, a first intermediate temperature increase end flag is set. That is, here, the process proceeds from the first intermediate heating step to the second intermediate heating step. Thereafter, the process returns to the main routine and proceeds to step S15 (see FIG. 3). In step S15, unlike the above-described cycle, since the first intermediate temperature increase step has already been completed (since the first intermediate temperature increase end flag is set), it is determined YES and the process proceeds to step S16. In the subroutine of step S16 (see FIG. 12), the second intermediate temperature increase energization is turned on in step S161. In the second intermediate temperature increase energization, the energization to the glow plug 1 is PWM-controlled based on the duty ratio Dt2 calculated in step S5 to maintain the ceramic heater 2 at the target temperature in the intermediate temperature increase glow step. Next, the process returns to the main routine and proceeds to step S17 (see FIG. 3). Then, after 12.5 ms elapses, the process returns to step S2.

  Next, in step S2, the current resistance value R of the ceramic heater 2 is calculated as in the previous cycle. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 4), but returns to the main routine through step S31 as in the previous cycle. Next, the process proceeds to a subroutine of step S4 (see FIG. 5). In step S41, YES is determined as in the previous cycle, and the process proceeds to step S42. In step S42, since there is still an intermediate temperature increase signal input, it is determined YES, the process proceeds to step S43, and the intermediate signal input flag is continuously set. Next, returning to the main routine, in step S5 (see FIG. 3), the respective duty ratios Dh, Dk, Da, Dt2 are calculated. During this second intermediate temperature raising step, the duty ratio Dt2 relating to this step is calculated. Duty ratios Dh, Dk, Da other than are not referenced. Next, the process proceeds to a subroutine of step S6 (see FIG. 6), and the duty ratio Dt1 is calculated, but this duty ratio Dt1 is not referred to during this period.

  Next, the process proceeds to step S7 (see FIG. 3). Since cranking is not in progress, it is determined NO, and further, the process proceeds to step S9, where the alternator is activated, so it is determined YES. Next, the process proceeds to a subroutine of step S10 (see FIG. 8), but returns to the main routine through steps S101 and S105 as in the previous cycle. Next, the process proceeds to a subroutine of step S12 (see FIG. 10), but returns to the main routine through steps S121, S122, and S126 as in the previous cycle. Next, the process proceeds to step S13 (see FIG. 3). As in the previous cycle, since the intermediate temperature increase glow step is being performed (because the intermediate temperature increase signal flag is set), YES is determined, and the process proceeds to step S14. . In the subroutine of step S14 (see FIG. 11), similarly to the previous cycle, the process returns to the main routine through steps S141 and S143, and proceeds to step S15. Next, in step S15 (see FIG. 3), since the first intermediate temperature raising step has already been completed, it is determined YES and the process proceeds to step S16. In the subroutine of step S16 (see FIG. 12), the second intermediate temperature increase energization is continuously turned on in step S161. Thereafter, the above cycle is repeated until the intermediate temperature rise signal is no longer input (see step S42 in FIG. 5).

  When the intermediate temperature rise signal is not input, NO is determined in step S42 of the subroutine of step S4 (see FIG. 5), the process proceeds to step S44, and the intermediate temperature rise signal flag is cleared. Next, returning to the main routine, in step S5 (see FIG. 3), the respective duty ratios Dh, Dk, Da, Dt2 are calculated. During this period, these duty ratios Dh, Dk, Da, Dt2 are Not referenced. Next, the process proceeds to a subroutine of step S6 (see FIG. 6), and the duty ratio Dt1 is calculated, but this duty ratio Dt1 is not referred to during this period. Next, the process proceeds to step S7 (see FIG. 3). Since cranking is not in progress, it is determined NO, and further, the process proceeds to step S9, where the alternator is activated, so it is determined YES. Next, the process proceeds to a subroutine of step S10 (see FIG. 8), but returns to the main routine through steps S101 and S105 as in the previous cycle. Next, the process proceeds to a subroutine of step S12 (see FIG. 10), but returns to the main routine through steps S121, S122, and S126 as in the previous cycle. Next, the process proceeds to step S13 (see FIG. 3). In step S13, unlike the above cycle, since the intermediate temperature increase glow step has already been completed (because the intermediate temperature increase signal flag is cleared), NO is determined, and the process proceeds to step S17. Then, after 12.5 ms elapses, the process returns to step S2. Accordingly, the second intermediate temperature raising energization is not performed (see step S16 in FIG. 3 and step S161 in FIG. 12).

  Next, in step S2, the current resistance value R of the ceramic heater 2 is calculated as in the previous cycle. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 4). In step S31, unlike the previous cycle, the pre-glow step is completed (the pre-glow end flag is set), not the post-starting glow step (the post-starting glow flag is cleared), and the intermediate temperature raising glow step Since it is not in the middle (because the intermediate temperature raising signal flag is cleared), it is determined YES and the process proceeds to step S32. Then, the start signal is captured and the process proceeds to step S33. In step S33, since a continuous start signal of 0.1 sec is not input, it is determined as NO and the process proceeds to step S35. In step S35, since no start signal is continuously input for 0.1 sec, it is determined as YES and the process proceeds to step S36. Then, the start signal flag is continuously cleared, and then the process returns to the main routine. Next, the process proceeds to a subroutine of step S4 (see FIG. 5). In step S41, YES is determined as in the previous cycle, and the process proceeds to step S42. In step S42, since the intermediate temperature rise signal is no longer input in the previous cycle, it is similarly determined NO, and the process returns to the main routine via step S44. Thereafter, such a cycle is repeated. As a result, as shown in FIG. 13, the temperature of the ceramic heater 2 decreases from the target temperature over time.

If the intermediate temperature rise signal is input again thereafter, YES is determined in step S42 of the subroutine of step S4 (see FIG. 5), and the process proceeds to step S43. In step S43, the intermediate temperature increase signal flag is set, and the intermediate temperature increase glow step starts again. That is, as described above, the first intermediate temperature raising step is first performed (in this embodiment, 2 seconds), and then the second intermediate temperature raising step is performed while the intermediate temperature raising signal is input.
The glow plug energization control device 101 of the present invention controls the energization to the glow plug 1 as described above.

As described above, the glow plug energization control device 101 includes a post-start glow unit and an intermediate temperature increase glow unit.
Among these, the after-start glow means is for stably heating the ceramic heater 2 after the engine is started. By such means, the ceramic heater 2 can be stably heated even after the engine is started, so that warming up of the combustion chamber of the engine is promoted, generation of diesel knock is prevented, generation of noise and white smoke, generation of HC components, etc. Emissions can be suppressed.
On the other hand, the intermediate temperature raising glow means controls the energization to the glow plug 1 so as to raise the temperature of the ceramic heater 2 to the target temperature again and maintain it after the end of the energization control by the post-start glow means. Is. As described above, even after the engine is started, black smoke or white smoke may be generated in the combustion chamber. By this intermediate temperature raising glow means, the ceramic heater 2 is heated to promote warming in the combustion chamber. Thus, generation of black smoke and white smoke can be suppressed.

However, in the case of PWM control of energization to the glow plug with the duty ratio based on the voltage value applied from the battery to the glow plug 1 according to the conventional method, as described above, since the initial temperature rise is slow, It takes time for the ceramic heater 2 to reach the target temperature. For this reason, even if black smoke or white smoke is generated in the combustion chamber, it cannot be immediately suppressed.
On the other hand, the intermediate temperature raising glow means of the present embodiment calculates the duty ratio Dt1 of the voltage waveform applied to the glow plug 1 based on the target resistance value Ro corresponding to the target temperature for the ceramic heater 2, and this First intermediate temperature raising means for PWM-controlling energization to the glow plug 1 with the duty ratio Dt1 is provided. Since there is a correlation between the resistance value R of the ceramic heater 2 and its temperature, if the duty ratio Dt1 based on the target resistance value Ro corresponding to the target temperature is used, the heater temperature is more accurately directed to the target temperature. Can raise the temperature. In addition, by performing PWM control of energization with such a duty ratio Dt1, the ceramic heater 2 can be rapidly heated in a short time compared to the conventional method. Therefore, even if black smoke or white smoke is generated in the combustion chamber for some reason, it can be immediately suppressed.

Furthermore, in this embodiment, it has a 2nd intermediate temperature rising means other than a 1st intermediate temperature raising means. This second intermediate temperature raising means has a duty ratio Dt2 of the voltage waveform applied to the glow plug 1 based on the voltage value applied from the battery BT to the glow plug 1 following the energization control by the first intermediate temperature raising means. And the energization to the glow plug 1 is PWM controlled by the duty ratio Dt2.
The first intermediate temperature raising means is excellent in rapid temperature raising of the ceramic heater 2, but the temperature variation near the target temperature may increase. On the other hand, although the second intermediate temperature raising means is inferior to the rapid temperature raising of the ceramic heater 2, it is easy to stably maintain the heater temperature at the target temperature. Therefore, the energization control is first performed by the first intermediate temperature raising means, and then the energization control is performed by the second intermediate temperature raising means, thereby enabling rapid temperature rise and stabilizing the heater temperature at the target temperature. Can be maintained.

In the present embodiment, the first intermediate temperature raising means has a duty ratio when the resistance value error ΔR of the ceramic heater 2 is given by ΔR1 = Ro−R and the control effective voltage value Vc1 is given by Vc1 = K0 + K1 · ΔR1. There is a calculation means for calculating the ratio Dt1 according to Dt1 = (Vc1) ² / (Vb) ² . By calculating the duty ratio Dt1 and controlling the energization to the glow plug 1 in this way, the temperature of the ceramic heater 2 can be raised more accurately toward the target temperature during the energization control by the first intermediate temperature raising means.

(Example 2)
Next, another embodiment will be described. In this embodiment, after the operator sets the key switch KSW to the ON position, after a while, the key switch KSW is set to the start position and the engine is started. This is the same as the first embodiment. However, in the present embodiment, a case will be described where a signal to be subjected to an intermediate temperature increase is input for some reason shortly thereafter, that is, before the temperature of the ceramic heater 2 is sufficiently lowered. In addition, description of the same part as the said Example 1 is abbreviate | omitted or simplified.
FIG. 14 shows the temperature change of the glow plug 1 (ceramic heater 2) when the glow plug energization control device 101 is used in this embodiment. The test conditions are the same as in Example 1 above.

(Pre-glow step)
First, when the operator sets the key switch KSW to the ON position, the pre-glow step is entered, and the ceramic heater 2 rises almost linearly to the target temperature (1250 ° C.) by energization control to the glow plug 1 by the pre-glow means ( (See FIG. 14). This pre-glow step is the same as in the first embodiment.
(Transition glow step)
When the pre-glow step ends, the process proceeds to the transition glow step. This transition glow step is also the same as in the first embodiment, and during this step, the ceramic heater 2 is maintained at the target temperature (1250 ° C.) to prevent a temperature drop (see FIG. 14).
(Cranking Glow Step)
If the key switch KSW is set to the start position before the predetermined time of the transition glow step has elapsed, the transition glow step shifts to the cranking glow step. This cranking glow step is also the same as in the first embodiment. During the cranking period, the energization to the glow plug 1 is PWM controlled so that the ceramic heater 2 is maintained at the target temperature (1250 ° C.), and the temperature is controlled. Prevent sagging. In addition, since the desktop test which shows a result in FIG. 14 is also performed in the absence of wind as in Example 1, the ultimate temperature of the ceramic heater 2 is as high as 1350 ° C.

(Glow step after startup)
When the engine starts, the cranking glow step shifts to the post-starting glow step. The glow step after start-up is also the same as in the first embodiment, and the ceramic heater 2 is set to the target temperature (1250 ° C.), and the energization to the glow plug 1 is PWM controlled so as to maintain the target temperature. In addition, since the desktop test whose result is shown in FIG. 14 is also performed in the absence of wind as in Example 1, the ultimate temperature of the ceramic heater 2 is as high as about 1400 ° C.
When a predetermined time of the glow step has elapsed after the start (see step S101 in FIG. 8), as described in the first embodiment, YES is determined in step S101, and the process proceeds to step S105. Then, the glow energization is turned off after starting. Further, the after-start glow flag is cleared, while the after-start glow end flag is set. Thereby, the after-start glow step ends. Then, as shown in FIG. 14, the temperature of the ceramic heater 2 starts to decrease.

(Intermediate temperature increase glow step)
When a signal to raise the intermediate temperature for some reason is input shortly after the glow step after the start, that is, before the temperature of the ceramic heater 2 sufficiently decreases, in step S42 of the subroutine of step S4 (FIG. 5), YES is determined, and the process proceeds to step S43. Then, an intermediate temperature rise signal flag is set. That is, the intermediate temperature raising glow step starts from here. In this intermediate temperature rise, the intermediate temperature rise glow step itself is the same as in the first embodiment. That is, first, the first intermediate temperature raising step is performed for a predetermined time (2 seconds), and the energization to the glow plug 1 is PWM-controlled so that the ceramic heater 2 rises to the vicinity of the target temperature (1250 ° C.). At this time, in the present embodiment, since the energization is not performed for a predetermined time, the heater temperature does not greatly exceed the target temperature. Subsequently, a second intermediate temperature raising step is performed, and the energization to the glow plug 1 is PWM controlled so that the ceramic heater 2 maintains the target temperature (1250 ° C.). In addition, since the desktop test whose result is shown in FIG. 14 is also performed in the absence of wind as in Example 1, the ultimate temperature of the ceramic heater 2 is as high as about 1400 ° C.
Thereafter, when the intermediate temperature rise signal is not input, the second intermediate temperature rise energization is not performed as in the first embodiment. As a result, as shown in FIG. 14, the temperature of the ceramic heater 2 is set to the target temperature. It will decline with the passage of time.

As described above, the intermediate temperature raising glow means of the present embodiment calculates the duty ratio Dt1 of the voltage waveform applied to the glow plug 1 based on the target resistance value Ro corresponding to the target temperature for the ceramic heater 2, First intermediate temperature raising means for PWM-controlling energization to the glow plug 1 with the duty ratio Dt1 is provided. Since there is a correlation between the resistance value of the ceramic heater 2 and its temperature, the heater temperature can be raised to the target temperature more accurately by using the duty ratio Dt1 based on the target resistance value Ro corresponding to the target temperature. it can. In addition, by performing PWM control of energization with such a duty ratio Dt1, it is possible to raise the temperature of the ceramic heater 2 in a shorter time than in the conventional method. Therefore, even if black smoke or white smoke is generated in the combustion chamber for some reason, it can be immediately suppressed. Also, as in this embodiment, when the intermediate temperature is raised immediately after the start of the glow control, the ceramic heater 2 greatly exceeds the target temperature, unlike the case where the energization of the glow plug 1 is continued for a certain time. To prevent the temperature from rising. For this reason, disconnection of the glow plug 1 can be prevented, and a decrease in durability of the glow plug 1 can be suppressed.
Other parts similar to those of the first embodiment have the same effects.

(Deformation)
Next, modifications of the above embodiment will be described. In this variation, the target resistance value Ro used for calculating the duty ratio Dt referred to during the first intermediate temperature raising step uses a preset resistance value. Therefore, the resistance value of the ceramic heater 2 is not memorized during the glow step after starting.
If it demonstrates with a flowchart, the subroutine (refer FIG. 15) of step S10 will differ from the subroutine (refer FIG. 8) of step S10 of the said embodiment. Specifically, step S103 and step S104 in the above embodiment do not exist. For this reason, the resistance value of the ceramic heater 2 during the glow step after starting is not stored.

  Even in such a glow plug energization control device, basically the same effect as in the above embodiment can be obtained. However, the heater resistance value is memorized during the glow step after starting and the second intermediate temperature raising step is performed using the memory resistance, so that there is an advantage that the variation in the actual reached temperature with respect to the target temperature can be reduced.

  In the above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof. .

It is sectional drawing of the glow plug which concerns on embodiment and is used. It is a circuit diagram showing a glow plug energization control device concerning an embodiment. It is a flowchart which shows the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the input process of a start signal among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the input process of an intermediate temperature rising signal among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about calculation of duty ratio Dt1 referred in the 1st middle temperature rising step among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the process of a cranking glow step among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the process of the glow step after starting among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the process of a pre-glow step among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the process of a transition glow step among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the process of a 1st intermediate temperature rising step among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the process of a 2nd intermediate | middle temperature rising step among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a graph which shows about the relationship between the time after making a key into an ON position and the temperature of a glow plug regarding Example 1. FIG. It is a graph which shows about the Example 2 about the relationship between the time after making a key into an ON position, and the temperature of a glow plug. It is a flowchart shown about the process of the glow step after starting among the electricity supply control by the glow plug electricity supply control apparatus which concerns on a modification.

Explanation of symbols

1 Glow plug 2 Ceramic heater (resistance heater)
101 Glow plug energization control device 111 Main control unit KSW Key switch BT Battery

Claims (6)

A glow plug energization control device that controls energization from a battery to a glow plug having a resistance heating heater installed in an engine when a key switch is in an on position and a start position,
A post-start glow means for stable heating of the resistance heater after the engine is started;
An intermediate temperature raising glow unit for controlling energization to the glow plug so as to raise the resistance heating heater to a target temperature and maintain the temperature after the end of energization control by the post-start glow unit. ,
A duty ratio Dt1 of a voltage waveform applied to the glow plug is calculated based on a target resistance value corresponding to the target temperature for the resistance heating heater, and the energization to the glow plug is PWM controlled by the duty ratio Dt1. Intermediate temperature raising glow means having first intermediate temperature raising means,
A glow plug energization control device comprising: The glow plug energization control device according to claim 1,
The intermediate temperature raising glow means includes
Following energization control by the first intermediate temperature raising means, a duty ratio Dt2 of a voltage waveform applied to the glow plug is calculated based on a voltage value applied from the battery to the glow plug, and this duty ratio Dt2 A glow plug energization control device having second intermediate temperature raising means for PWM-controlling energization to the glow plug by The glow plug energization control device according to claim 1 or 2,
The first intermediate heating means
The current resistance value of the resistance heating heater is R, the resistance value when the resistance heating heater reaches the target temperature is Ro, the voltage applied to the glow plug is Vb, and the error ΔR1 is ΔR1 = Ro−R. A glow plug energization control device having a calculating means for calculating the duty ratio Dt1 according to Dt1 = (Vc1) ² / (Vb) ² when the effective control voltage value Vc1 is given by Vc1 = K0 + K1 · ΔR1. A glow plug energization control method for controlling energization from a battery to a glow plug having a resistance heating heater installed in an engine when a key switch is in an on position and a start position,
A post-start glow step for stable heating of the resistance heater after the engine is started;
An intermediate temperature raising glow step for controlling energization to the glow plug so as to raise the resistance heating heater to a target temperature and maintain the temperature after the end of the after-start glow step,
A duty ratio Dt1 of a voltage waveform applied to the glow plug is calculated based on a target resistance value corresponding to the target temperature for the resistance heating heater, and the energization to the glow plug is PWM controlled by the duty ratio Dt1. An intermediate warming glow step having a first intermediate warming step;
A glow plug energization control method comprising: A glow plug energization control method according to claim 4,
The intermediate temperature raising glow step includes:
Following the first intermediate temperature raising step, a duty ratio Dt2 of a voltage waveform applied to the glow plug is calculated based on a voltage value applied from the battery to the glow plug, and the glow ratio is calculated based on the duty ratio Dt2. A glow plug energization control method comprising: a second intermediate temperature raising step for PWM-controlling energization of the plug. A glow plug energization control method according to claim 4 or claim 5, wherein
The first intermediate heating step includes
The current resistance value of the resistance heating heater is R, the resistance value when the resistance heating heater reaches the target temperature is Ro, the voltage applied to the glow plug is Vb, and the error ΔR1 is ΔR1 = Ro−R. And a calculation step of calculating the duty ratio Dt1 according to Dt1 = (Vc1) ² / (Vb) ² when the control effective voltage value Vc1 is given by V1c = K0 + K1 · ΔR1.

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