JP2005042628A - Method for controlling diesel engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling a diesel engine accurately measuring temperature of an exoergic resistance coil and surely controlling the exoergic resistance coil based on the measured value. <P>SOLUTION: A glow plug 1 including a sheathed heater 2 provided in a combustion chamber of the diesel engine and generating heat by current carry, and a glow plug current carry control device 30 controlling current carry to the exoergic resistance coil 5 of the sheathed heater 2 are used. In the glow plug 1, temperature sensing points 10c of thermocouples 10a, 10b capable of outputting temperature of the exoergic resistance coil 5 as output signal are positioned inside of the exoergic resistance coil 5 of the glow plug 1. The glow plug current carry control device 30 executes the feedback control of output signal of the thermocouples 10a, 10b for current carry to the exoergic resistance coil 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a diesel engine control method.

  Conventionally, the diesel engine control method of patent document 1 is known. This diesel engine control method uses a glow plug that is provided in a combustion chamber of a diesel engine and has a heater section that generates heat when energized, and a glow plug control means that controls energization of the heater section, and generates heat by heating the heater section. Based on the resistance value of the resistance coil, energization to the heating resistance coil is controlled by the glow plug control means. Specifically, when the key switch is turned on, the glow plug control means applies a large current to the heating resistor coil for a certain period of time, and the target temperature (for example, 1000) sufficient for the heater unit to start the diesel engine. ° C). This period is called the pre-glow period. Once the target temperature is reached, the glow plug control means measures the resistance value of the heating resistor coil, compares the resistance value with the target resistance value corresponding to the target temperature, and controls the temperature of the heater section. That is, when the resistance value of the heating resistor coil is larger than the target resistance value, the glow plug control means turns off the energization to the heating resistor coil, and when the resistance value of the heating resistor coil is smaller than the target resistance value, Turn on the power.

  However, in the conventional diesel engine control method, the relationship between the resistance value and the temperature is not stable during the pre-glow period, so the temperature of the heating resistor coil cannot be estimated from the resistance value of the heating resistor coil. Also, after the pre-glow period, the temperature can be estimated by measuring the resistance value of the heating resistor coil, but it is difficult to accurately control the temperature of the heating resistor coil because the temperature is not directly measured. It is. This is presumably because the temperature fluctuation range of the heating resistor coil is widened because there is a time lag between the resistance value and the temperature of the heating resistor coil. Here, if the temperature of the heating resistor coil is too higher than the target temperature, the heat resistance temperature of the heating resistor coil is reached, and there is a problem that the durability of the glow plug decreases due to problems such as disconnection. Also, if the temperature of the heating resistor coil is too lower than the target temperature, it will be difficult to start the engine before starting the engine, and it will cause diesel knock, noise, white smoke, HC component, etc. after starting the engine. Will occur.

  For this reason, a glow plug in which a thermocouple as a temperature sensing element is embedded in the diesel engine control method described in Patent Document 2 has been proposed. In this glow plug, as shown in FIG. 11, a heater portion 81 is brazed to a metal outer cylinder 80 so that a tip end portion 81a is exposed to the outside. The outer cylinder 80 is brazed to a housing (not shown). The heater unit 81 includes a substantially U-shaped ceramic heating element (an energizing heating element) 82 and a ceramic base 83 that covers the energizing heating element 82. Further, a groove 84 is formed in the outer periphery of the ceramic substrate 83 along the axial direction (vertical direction in the figure), and a thermocouple 87 in which the leading ends of the lead wires 85 and 86 are welded is covered with cement 88 in the groove 84. It has been buried. According to this diesel engine control method, since the temperature is directly measured by the thermocouple 87, it is possible to measure the temperature of the energization heating element 82 even during the pre-glow period, and between the resistance value and the temperature of the energization heating element 82. This time lag can be eliminated.

JP 61-46470 A JP 2001-336468 A

  However, in the diesel engine control method described in Patent Document 2, the temperature sensing element is arranged in the vicinity of the surface of the heater unit for detecting the ionic current. When a glow plug is attached to the combustion chamber of a diesel engine, the temperature sensing element may be cooled by the swirl depending on the direction in which the glow plug is installed, and the measured temperature differs between the energization heating element and the temperature sensing element. It is not always possible to accurately measure body temperature.

  The present invention has been made in view of the above-described conventional situation, and is a diesel engine control method capable of accurately measuring the temperature of a heating resistor coil and reliably controlling the heating resistor coil based on the measured value. Providing is an issue to be solved.

The diesel engine control method of the present invention includes a heater part that generates heat when energized, a glow plug that is attached in such a manner that the tip of the heater part protrudes into a combustion chamber of the diesel engine, and controls energization of the heater part. In a diesel engine control method for controlling the diesel engine using a glow plug control means,
The glow plug has a heating resistor coil that heats the heater unit by energization, and a temperature sensing point of a temperature sensing element capable of outputting the temperature of the heater unit by the heating resistor coil as an output signal is located inside the heating resistor coil. Is located in
The glow plug control means feedback-controls the output signal of the temperature sensing element to energize the heating resistor coil.

  In the diesel engine control method of the present invention, a glow plug in which the temperature sensing point of the temperature sensing element is located inside the heating resistance coil is used, and the energization to the heating resistance coil is feedback controlled by the output signal of the temperature sensing element. In this glow plug, since the temperature sensing point of the temperature sensing element is located inside the heating resistance coil, there is no directionality, and when it is installed in the combustion chamber of a diesel engine, the measured temperature does not vary depending on the installation direction. . Further, since the temperature sensitive element is hardly cooled by swirl, the temperature of the heating resistor coil can be accurately measured. Further, the temperature of the heating resistor coil can be accurately measured not only after the pre-glow period but also during the pre-glow period. Therefore, in the diesel engine control method using this glow plug, it is possible to perform control based on the accurate temperature of the heating resistor coil.

  Therefore, according to the diesel engine control method of the present invention, the temperature of the heating resistor coil can be accurately measured, and the heating resistor coil can be reliably controlled based on the measured value. Thereby, in the diesel engine control method of the present invention, the durability of the glow plug is improved, the engine can be easily started, and the generation of diesel knock, noise, white smoke, HC components, etc. can be reduced. it can.

  The glow plug control means energizes the heating resistor coil based on an output signal of the temperature sensing element in a pre-glow period in which the temperature of the heating resistor coil is set to a predetermined temperature and a cranking period in which the starter is driven. It is preferable to perform on / off control. In the pre-glow period, it is desirable that the heating resistance coil has a temperature sufficient to start the diesel engine in as short a time as possible. Further, during the cranking period, the temperature of the heating resistor coil suddenly decreases due to the swirl, so that it is necessary to quickly increase the temperature of the heating resistor coil. For these reasons, it is desirable to control on and off as much current as possible to the heating resistor coil based on the output signal of the temperature sensing element during the pre-glow period and the cranking period. As a result, the engine can be easily started.

  Further, it is preferable that the glow plug control means performs duty ratio control of energization to the heating resistor coil based on an output signal of the temperature sensing element during an after glow period after starting the diesel engine. Even after the diesel engine is started, combustion remains unstable for a while. For this reason, in the afterglow period, it is desirable to maintain the temperature of the heating resistance coil at a certain level by controlling the duty ratio of the energization to the heating resistance coil. Specifically, the predetermined temperature is selected from the range of 500 ° C to 900 ° C. Below 500 ° C., the effect of reducing diesel knock, noise, white smoke, generation of HC components, etc. is low, and when it exceeds 900 ° C., the burden on the glow plug is large and the durability tends to decrease.

  In the diesel engine control method of the present invention, it is preferable that the diesel engine control method further comprises a notification means for notifying the possibility of cranking based on the output signal of the temperature sensing element. Thereby, a driver | operator can know the timing which makes a key switch a start position.

  The diesel engine control method of the present invention may further include a fuel injection device control means for controlling the fuel injection device based on an output signal of the temperature sensing element. In the diesel engine control method of the present invention, the output signal of the temperature sensing element can be used as the input signal of the fuel injection device control means by measuring the temperature of the combustion chamber after the engine has rotated.

  In the diesel engine control method of the present embodiment, the glow plug 1 shown in FIG. 1 is used. The glow plug 1 includes a sheathed heater 2 and a metal shell 3 disposed so as to fit the rear end side thereof. As shown in FIG. 2, the sheathed heater 2 has a heating resistance coil 5 and a control coil 6 enclosed with a magnesia powder 7 as an insulating material inside the sheathed tube 4 whose tip 4 a is closed. However, the heating resistor coil 5 may be used alone without necessarily using the heating resistor coil 5 and the control coil 6. The heating resistor coil 5 and the control coil 6 are connected in series by welding, and the tip 5a of the heating resistor coil 5 is connected to the tip 4a of the sheath tube 4 by welding. Further, the rear end 6b of the control coil 6 is connected by welding to the distal end 8a of the second middle shaft 8 that supplies current to the heating resistor coil 5 and the control coil 6. Therefore, although the tip 5a of the heating resistor coil 5 is electrically connected to the sheath tube 4, the heating resistor coil 5 and the control coil 6 other than the tip 5a and the sheath tube 4 are insulated by the intervention of the magnesia powder 7. ing. That is, the current supplied via the second middle shaft 8 flows through the control coil 6, the heating resistor coil 5, and the sheath tube 4. On the other hand, an insulating outer tube 9 passes through the second middle shaft 8, and the distal end 9 a of the insulating outer tube 9 is disposed near the distal end 4 a of the sheath tube 4 and at the highest heat generating portion of the heating resistor coil 5. More specifically, the distal end 9 a of the insulating outer tube 9 is disposed within 5 mm from the distal end 4 a of the sheath tube 4. Thermocouples 10a and 10b as temperature sensitive elements are housed in the insulating outer tube 9 together with the insulating material 11, and the temperature sensitive point 10c of the thermocouples 10a and 10b is fixed to the tip 9a of the insulating outer tube 9 by welding. .

  Here, the heating resistance coil 5 has an electric specific resistance R20 at 20 ° C. of 80 μΩ · cm to 200 μΩ · cm, an electric specific resistance at 1000 ° C. of R1000, and R1000 / R20 of 0.8 to 3 or less. These materials, specifically, Fe—Cr alloy or Ni—Cr alloy are used. On the other hand, the control coil 6 is made of, for example, a material having an electric specific resistance R20 at 20 ° C. of 5 μΩ · cm to 20 μΩ · cm, an electric specific resistance at 1000 ° C. of R1000, and R1000 / R20 of 6 to 20 Specifically, it is made of Ni, Co—Fe alloy, Co—Ni—Fe alloy or the like.

  As shown in FIG. 1, a hexagonal cross-section tool engagement portion for engaging a tool such as a torque wrench on the outer peripheral surface on the rear end 3b side of the metal shell 3 when the glow plug 1 is attached to a diesel engine. 3e is formed, and a screw portion 3c for attachment is formed following the tool engaging portion 3e. The metal shell 3 has a through hole 3d, and the rear end 4b of the sheath tube 4 is fixed from the front end 3a side by press fitting, brazing, or the like. A seal 12 is provided in the through hole 3 d of the metal shell 3 adjacent to the rear end 4 b of the sheath tube 4. Further, the second middle shaft 8 protrudes from the rear end 4b of the sheath tube 4 through the seal 12, and the rear end 8b of the second middle shaft 8 is in the through hole 3d on the rear end 3b side of the metal shell 3. And the tip 13a of the first middle shaft 13 are connected by brazing. The first middle shaft 13 has a through hole 13d, and the insulating outer tube 9 protruding from the second middle shaft 8 is fixed in the through hole 13d of the first middle shaft 13 with its rear end positioned.

  As shown in FIG. 3, the rear end 13b of the first intermediate shaft 13 protrudes from the rear end 3b of the metal shell 3, and a threaded portion 13c is formed on the outer periphery of the rear end 13b. An insulating bush 14 is provided between the first middle shaft 13 and the rear end 3b of the metal shell 3, and the insulating bush 14 is fixed by a round nut 15 that is screwed into the screw portion 13c from the rear end side. Thereby, the first middle shaft 13 and the second middle shaft 8 are fixed in the through hole 3d of the metal shell 3, and the insulation between the first middle shaft 13, the second middle shaft 8 and the metal shell 3 is also ensured. Therefore, the current supplied from the first middle shaft 13 flows through the second middle shaft 8, the control coil 6, the heating resistor coil 5, the sheath tube 4, and the metal shell 3. Further, from the rear end 9b of the insulating outer tube 9, thermocouples 10a and 10b pass through the through hole 13d and project outside the first middle shaft 13. The thermocouples 10a and 10b are covered with a covering material 17 made of resin, and the through hole 13d is closed with a sealing material 16 made of resin at the rear end 13b.

  Next, an electric circuit used in the diesel engine control method of the present embodiment will be described. FIG. 4 is a block diagram showing an electrical configuration centering on the glow plug energization control device 30 as the glow plug control means. The glow plug energization control device 30 includes a main control unit 31, a power supply circuit 32, and switching elements SW1 to SWn. The main control unit 31 includes a microcomputer and an interface circuit (not shown). The power supply circuit 32 is a circuit that generates a stable DC voltage. The switching elements SW1 to SWn are elements that switch a large current, such as an FET.

  When the key switch KSW is set to the ON position or the START position, power is supplied from the positive terminal of the battery BT to the power supply circuit 32, and a stable DC voltage is supplied to the main control unit 31 by the power supply circuit 32. Therefore, when the key switch KSW is set to the ON position or the START position, the main control unit 31 starts its operation, and when the key switch KSW is set to the OFF position, the main control unit 31 stops its operation. Here, the key switch KSW has a structure in which the battery BT and the power supply circuit 32 are connected both in the ON position and in the START position. When the key switch KSW is set to the START position, a START signal is input to the main control unit 31. The START signal is input to the microcomputer in the main control unit 31 via an interface circuit including a voltage conversion circuit and a waveform shaping circuit. In the following description, description of the interface circuit for input / output signals to the main control unit 31 is omitted.

  The positive terminal of the battery BT is connected to the drains of the n switching elements SW1 to SWn. The sources of the switching elements SW1 to SWn are connected to n glow plugs GP1 to GPn. The glow plug 1 shown in FIG. 1 is used as each of the glow plugs GP1 to GPn. The gates of the switching elements SW1 to SWn are connected to the main control unit 31, and energization from the battery BT to the glow plugs GP1 to GPn is turned on / off by an output signal from the main control unit 31 to the gate. Accordingly, the main controller 31 can turn on / off the energization of the heating resistor coil 5 by turning on / off the output signal to the gate at a predetermined timing, and can be turned on / off based on a predetermined duty ratio. For example, the duty ratio control (PWM control) can be applied to the heating resistor coil 5. Further, the thermocouples of the respective glow plugs GP <b> 1 to GPn are connected to the main control unit 31, whereby the temperature of the heating resistor coil 5 is input to the main control unit 31. Further, the main control unit 31 and the glow lamp L are connected, and the glow lamp L is turned on or off according to an output signal from the main control unit 31.

  The main control unit 31 is connected to an engine control unit (hereinafter abbreviated as ECU) having a microcomputer, and can communicate in both directions. Further, the main controller 31 and the alternator 34 are connected, and a drive signal for the alternator 34 is input to the main controller 31.

  Next, an outline of a diesel engine control method for controlling the glow plugs GP1 to GPn by the glow plug energization control device 30 will be described with reference to FIG. When the key switch KSW is turned from the OFF position to the ON position, control by the glow plug energization control device 30 is started and the pre-glow period starts. During the pre-glow period, the glow plug energization control device 30 turns on the glow lamp L and energizes the glow plug 1 from the battery BT, and the temperature of the heating resistor coil 5 is a target temperature (a temperature sufficient to start the engine). For example, 1000 ° C.) in a short time. When the temperature of the heating resistor coil 5 reaches the target temperature, the glow plug energization control device 30 turns off the glow lamp L so that the driver can know the timing for setting the key switch KSW to the START position. Thereafter, the glow plug energization control device 30 maintains the temperature of the heating resistor coil 5 at the target temperature. When the key switch KSW is set to the START position during the pre-glow period, the cranking period starts when the starter starts. Further, when the key switch KSW is left for a predetermined time without being set to the START position (key-on leaving), the energization to the glow plug 1 is stopped. During the cranking period, the glow plug energization control device 30 suppresses the temperature drop of the heating resistor coil 5 and improves the startability of the engine. When the engine starts, the cranking period shifts to the afterglow period. During the afterglow period, the glow plug energization control device 30 performs PWM control of energization to the glow plug 1 to maintain the temperature of the heating resistor coil 5 at a predetermined temperature (for example, 900 ° C.). Then, after a predetermined time (for example, 180 seconds) has elapsed, the energization of the glow plug 1 is stopped.

  Next, a diesel engine control method for controlling the glow plugs GP1 to GPn by the glow plug energization control device 30 will be described with reference to the flowcharts shown in FIGS. When the key switch KSW is turned from the OFF position to the ON position, power is supplied from the battery BT to the power supply circuit 32, and a stable DC voltage is supplied to the main control unit 31 by the power supply circuit 32. Thereby, execution of the main program shown in FIG. 6 is started.

  When the execution of the main program is started, step S1 is first executed. In step S1, after starting a timer for measuring a cycle (12.5 ms) in which the main program is executed, start signal input processing is performed, and a start signal input processing subroutine shown in FIG. 7 is executed. In step S101 of the start signal input processing subroutine, it is determined whether it is a pre-glow period or a cranking period. If it is the pre-glow period or the cranking period (YES), the process proceeds to step S102. If it is not the pre-glow period or the cranking period (NO), that is, if it is an after-glow period, the process returns to the main program. Therefore, the start signal input processing subroutine is performed only in the pre-glow period or the cranking period, and is not performed in the after-glow period. In the pre-glow period, it is necessary to monitor the START signal of the key switch KSW for shifting to the cranking period, and in the cranking period, it is necessary to monitor the START signal of the key switch KSW for shifting to the after-glow period. Because.

  In step S102, the START signal of the key switch KSW is input, and it is checked whether the START signal is continuously ON for 0.1 seconds. Specifically, as will be described later, since the main program is executed every 12.5 msec, it is checked whether or not the START signal is ON for 8 consecutive periods. If the START signal is ON continuously for 0.1 second (YES), the process proceeds to step S104. If the START signal is not ON continuously for 0.1 seconds (NO), the process proceeds to step S103. In step S103, it is checked whether or not the START signal is continuously OFF for 0.1 seconds. Also in this case, it is checked whether the START signal is OFF for 8 consecutive periods. If the START signal is OFF for 0.1 seconds continuously (YES), the process proceeds to step S105. If the START signal is not OFF continuously for 0.1 second (NO), the process returns to the main program. In step S104, it stores that the key switch KSW is in the START position, and returns to the main program. In step S105, it is stored that the key switch KSW is not in the START position, and the process returns to the main program. However, the history of the state of the key switch KSW such as when the key switch KSW is once turned off after being set to the START position is also stored. Here, when the START signal is continuously ON or OFF for 0.1 seconds, the key switch KSW is assumed to be in the START position or not in the START position. This is to avoid it.

  Next, in step S2 of FIG. 6, the temperatures of the glow plugs GP1 to GPn are input. Specifically, the signals of the thermocouples 10a and 10b of the glow plug 1 are A / D converted and input and stored. Then, the process proceeds to step S3.

  In step S3, it is checked whether or not it is a cranking period. If it is the cranking period (YES), the process proceeds to step S6, and if not the cranking period (NO), the process proceeds to step S4. In step S4, it is checked whether or not it is an afterglow period. If it is the afterglow period (YES), the process proceeds to step S7. If it is not the afterglow period (NO), that is, if it is the pre-glow period, the process proceeds to step S5. Here, whether the pre-glow period, the cranking period, or the after-glow period is determined is determined based on the history of the state of the key switch KSW, and is stored using, for example, a flag.

  In step S5, a pre-glow process is performed, and a pre-glow process subroutine shown in FIG. 8 is executed. In step S501 of the pre-glow processing subroutine, it is checked whether or not the temperature of the heating resistor coil 5 of the glow plug 1 has reached the target temperature (1000 ° C.) even once. If the target temperature has been reached (YES), the process proceeds to step S510. If the target temperature has not been reached (NO), the process proceeds to step S502. Note that the fact that the target temperature has been reached is stored by the target temperature reaching process in step S505 described later.

  In step S502, the current temperature is compared with the target temperature. If the current temperature is equal to or higher than the target temperature (YES), the process proceeds to step S503. If the current temperature is lower than the target temperature (NO), the process proceeds to step S506. Here, the current temperature is the temperature stored in step S2. In step S503, the glow lamp L is turned off, the driver is informed that the temperature of the heating resistor coil 5 is sufficient to start the engine, and the process proceeds to step S504. Accordingly, the driver can know the timing for starting the engine by setting the key switch KSW to the START position. In step S504, the pre-glow energization is turned off, and the process proceeds to step S505. Here, turning off the pre-glow energization specifically means turning off the energization from the battery BT to the glow plugs GP1 to GPn by turning off the output signal from the main control unit 31 to the gates of the switching elements SW1 to SWn. It is to be. In step S505, it is stored that the target temperature has been reached, a timer for measuring the heat retention time is started, and the process returns to the main program.

  In step S506, the glow lamp L is turned on to inform the driver that the temperature of the heating resistor coil 5 is not yet sufficient to start the engine, and the process proceeds to step S507. In step S507, the pre-glow energization is turned on and the process returns to the main program. Here, turning on the pre-glow energization specifically means energizing directly from the battery BT to the glow plugs GP1 to GPn by turning on the output signal from the main control unit 31 to the gates of the switching elements SW1 to SWn. It is.

  In step S510, it is checked whether or not the heat retention time has elapsed. The heat retention time is 30 seconds after the temperature of the heating resistor coil 5 of the glow plug 1 reaches the target temperature for the first time, and when the heat retention time has elapsed, it is determined that the key-on is left. Note that the measurement of the heat retention time is based on the timer started in step S505 described above. When the heat retention time has elapsed (YES), the process proceeds to step S514, and when the heat retention time has not elapsed (NO), the process proceeds to step S511. In step S511, the current temperature is compared with the target temperature. If the current temperature is equal to or higher than the target temperature (YES), the process proceeds to step S512. If the current temperature is lower than the target temperature (NO), the process proceeds to step S513. Here, the current temperature is the temperature stored in step S2. In step S512, the heat insulation energization is turned off and the process returns to the main program. Here, turning off the heat insulation energization specifically turns off the energization from the battery BT to the glow plugs GP1 to GPn by turning off the output signal from the main control unit 31 to the gates of the switching elements SW1 to SWn. It is to be. In step S513, the heat insulation energization is turned on and the process returns to the main program. Here, turning on the heat insulation energization specifically means energizing directly from the battery BT to the glow plugs GP1 to GPn by turning on the output signal from the main control unit 31 to the gates of the switching elements SW1 to SWn. It is. In the present embodiment, the pre-glow energization and the heat insulation energization are both direct energization from the battery BT to the glow plugs GP1 to GPn, but the heat insulation energization can also be performed by PWM control.

  Further, in step S514, the heat insulation energization is turned off, and the process proceeds to step S515. In step S515, the fact that the heat retention time has elapsed is stored (key-on leaving), and the process returns to the main program.

  Further, in step S6 of FIG. 6, a cranking process is performed, and a cranking process subroutine shown in FIG. 9 is executed. In step S61 of the cranking process subroutine, the current temperature is compared with the target temperature (1000 ° C.). If the current temperature is equal to or higher than the target temperature (YES), the process proceeds to step S62. If the current temperature is lower than the target temperature (NO), the process proceeds to step S63. Here, the current temperature is the temperature stored in step S2. In step S62, the cranking energization is turned off and the process returns to the main program. In step S63, the cranking energization is turned on and the process returns to the main program. Here, to turn on / off the cranking energization, specifically, by turning on / off the output signal from the main control unit 31 to the gates of the switching elements SW1 to SWn, the glow plugs GP1 to GP1 are connected to the battery BT. The energization to GPn is directly turned ON / OFF, which is the same as the ON / OFF of pre-glow energization and heat insulation energization. In addition, cranking energization can also be based on PWM control. Furthermore, in this embodiment, the target temperature for pre-glow energization and heat insulation energization and the target temperature for cranking energization are both 1000 ° C., but they may be set to different temperatures.

  Further, in step S7 of FIG. 6, afterglow processing is performed, and an afterglow processing subroutine shown in FIG. 10 is executed. In step S71 of the after glow processing subroutine, after glow start processing is performed only once at the beginning of the after glow period. In the afterglow start process, a timer for measuring afterglow time (180 seconds) is started, pre-glow energization, heat insulation energization and cranking energization are turned off, and the glow lamp L is turned off. The afterglow start process of step S71 is executed only once at the beginning of the afterglow period, and is not executed thereafter (algorithm is omitted). After execution of step S71, step S72 is executed.

  In step S72, it is checked whether the engine stall is in progress. When the alternator 34 is not activated (YES), it is determined that the engine is stalled, and the process proceeds to step S73. If the alternator 34 is being activated (NO), it is determined that the engine is not being stalled, and the process proceeds to step S74. In step S73, the afterglow energization is turned off and the process returns to the main program. In step S74, it is checked whether or not the afterglow time has elapsed. If 180 seconds have elapsed since the start of the afterglow period (YES), it is determined that the afterglow time has elapsed, and the process proceeds to step S75. If 180 seconds have not elapsed since the start of the afterglow period (NO), it is determined that the afterglow time has not elapsed, and the process proceeds to step S76. The afterglow time is measured by the timer started in step S71. In step S75, the fact that the afterglow time has elapsed is stored, and the process proceeds to step S73.

  In step S76, the current temperature is compared with the target temperature (900 ° C.). If the current temperature is equal to or higher than the target temperature (YES), the process proceeds to step S77. If the current temperature is lower than the target temperature (NO), the process proceeds to step S78. Here, the current temperature is the temperature stored in step S2. In step S77, the afterglow energization is turned off and the process returns to the main program. In step S78, afterglow energization is turned on and the process returns to the main program. Here, afterglow energization is based on PWM control.

  Further, in step S8 of FIG. 6, it is checked whether or not key-on is left. If the heat retention time has elapsed (YES), it is determined that the key-on is left, and the process proceeds to step S11. If the heat retention time has not elapsed (NO), it is determined that the key-on is not left, and the process proceeds to step S9. Note that the storage of the state in which the heat retention time has elapsed is performed in step S515 in the pre-glow processing subroutine.

  In step S9, it is checked whether or not the afterglow time has elapsed. If the afterglow time has elapsed (YES), the process proceeds to step S12. If the afterglow time has not elapsed (NO), the process proceeds to step S10. Note that the storage of the state in which the afterglow time has elapsed is performed in step S75 of the afterglow processing subroutine.

  In step S10, it is checked whether 12.5 ms has elapsed. If 12.5 ms has elapsed (YES), the process returns to step S1. If 12.5 ms has not elapsed (NO), step S10 is repeated until it has elapsed. This 12.5 ms is the time from the start of execution of step S1, and a timer for measuring this time is started in step S1. As a result, the main program is executed every 12.5 msec.

  In step S11, the main control unit 31 completely turns off the energization of the glow plugs GP1 to GPn, lights up the glow lamp L, and ends the main program. After the main program is terminated, a program (not shown) is activated, and information indicating that the key-on state is left is transmitted to the ECU 33. In this state, the main program is not executed again unless the key switch KSW is once set to the OFF position and then turned to the ON position.

  In step S12, the main control unit 31 completely turns off the energization of the glow plugs GP1 to GPn and ends the main program. In this case, a series of controls are normally performed, and the engine is rotating normally. Then, after finishing the main program, a program (not shown) is started. This program transmits the temperature of the glow plugs GP1 to GPn to the ECU 33 in response to a request from a program for controlling energization of the fuel injection device existing in the ECU 33.

  In the diesel engine control method of the present embodiment, the glow plug 1 in which the temperature sensitive points 10c of the thermocouples 10a and 10b are located inside the heating resistor coil 5 is used, and the heating resistors 10a and 10b output signals to the heating resistor coil 5. The feedback of the energization is controlled. The glow plug 1 has a directivity because the temperature sensitive point 10c of the thermocouples 10a and 10b is located inside the heating resistor coil 5, and is measured according to the mounting direction when it is mounted in the combustion chamber of a diesel engine. The temperature is not different. Further, since the thermocouples 10a and 10b are rarely cooled by the swirl, the temperature of the heating resistor coil 5 can be accurately measured. Further, the temperature of the heating resistor coil 5 can be accurately measured not only after the pre-glow period but also during the pre-glow period. Therefore, in the diesel engine control method using the glow plug 1, accurate control based on the temperature of the heating resistor coil 5 is possible.

  In the diesel engine control method, during the pre-glow period, the heating resistor coil 5 is required to have a temperature sufficient to start the diesel engine in as short a time as possible. Further, during the cranking period, the temperature of the heating resistor coil 5 rapidly decreases due to swirling, and therefore, it is required to quickly raise the temperature of the heating resistor coil 5 and stabilize it. In this diesel engine control method, during the pre-glow period and the cranking period, on / off control of a large current to the heating resistor coil 5 is performed based on the output signals of the thermocouples 10a and 10b, so that the above requirement can be satisfied. The engine can be easily started.

  Further, in the diesel engine control method, the unstable combustion state usually continues for a while even after the diesel engine is started. In this diesel engine control method, during the afterglow period after starting the diesel engine, the energization to the heating resistor coil 5 is PWM controlled to keep the temperature of the heating resistor coil 5 constant. Smoke, generation of HC components, etc. can be reduced.

  Therefore, according to the diesel engine control method of this embodiment, the temperature of the heating resistor coil 5 can be accurately measured, and the heating resistor coil 5 can be reliably controlled based on the measured value. Thereby, in the diesel engine control method of the present invention, the durability of the glow plug 1 can be improved, the engine can be easily started, and the generation of diesel knock, noise, white smoke, HC components, etc. can be reduced. Can do.

  In addition, since the diesel engine control method includes the glow lamp L that notifies the possibility of cranking based on the output signals of the thermocouples 10a and 10b, the driver knows when the key switch KSW is set to the START position. be able to.

  Further, in this diesel engine control method, the output signals of the thermocouples 10a and 10b can be used as the input signals of the fuel injection device control means after the engine has rotated.

  The present invention is applicable to a diesel engine control method using a glow plug.

1 is a cross-sectional view of a glow plug according to an embodiment. It is a partial expanded sectional view of a glow plug concerning an embodiment. It is a partial expanded sectional view of a glow plug concerning an embodiment. 1 is a block diagram illustrating an electrical configuration according to an embodiment. It is a graph which concerns on embodiment and shows the relationship between time and the temperature of a glow plug. 4 is a flowchart of a main program according to the embodiment. 7 is a flowchart of a start signal input processing subroutine program according to the embodiment. 6 is a flowchart of a pre-glow processing subroutine program according to the embodiment. 10 is a flowchart of a cranking process subroutine program according to the embodiment. 10 is a flowchart of an afterglow processing subroutine program according to the embodiment. It is a partial expanded sectional view of the conventional glow plug.

Explanation of symbols

1 ... Glow plug 2 ... Heater (seeds heater)
30. Glow plug control means (glow plug energization control device)
10a, 10b ... temperature sensitive element (thermocouple)
10c ... temperature sensing point 5 ... heating resistance coil L ... notification means (glow lamp)

Claims (5)

A glow plug that is provided with a heater portion that generates heat when energized, is attached in a form that projects the tip of the heater portion into a combustion chamber of a diesel engine, and a glow plug control means that controls energization to the heater portion, In a diesel engine control method for controlling a diesel engine,
The glow plug has a heating resistor coil that heats the heater unit by energization, and a temperature sensing point of a temperature sensing element capable of outputting the temperature of the heater unit by the heating resistor coil as an output signal is located inside the heating resistor coil. Is located in
The diesel engine control method, wherein the glow plug control means feedback-controls the output signal of the temperature sensing element to energize the heating resistor coil.   The glow plug control means energizes the heating resistor coil based on an output signal of the temperature sensing element in a pre-glow period in which the temperature of the heating resistor coil is set to a predetermined temperature and a cranking period in which the starter is driven. 2. The diesel engine control method according to claim 1, wherein on / off control is performed.   3. The glow plug control means performs duty ratio control of energization to the heating resistor coil based on an output signal of the temperature sensing element during an after glow period after starting the diesel engine. Diesel engine control method.   The diesel engine control method according to any one of claims 1 to 3, further comprising notification means for notifying that cranking is possible based on an output signal of the temperature sensing element.   The diesel engine control method according to any one of claims 1 to 4, further comprising fuel injection device control means for controlling the fuel injection device based on an output signal of the temperature sensing element.

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