JP5475219B2 - Glow plug energization control device - Google Patents

Description

  The present invention relates to a glow plug energization control device that controls 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 glow plug is controlled so that the temperature of the resistance heating heater rises toward a target temperature (for example, 1000 ° C.) sufficient to start the engine. Controls energization to supply high 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 this target temperature within a few seconds. Next, after the temperature of the resistance heating heater reaches the target temperature, the glow plug is energized so that the temperature of the resistance heating heater maintains the target temperature (for example, 900 ° C.) for a predetermined period (for example, 180 seconds). Is controlled to supply relatively small power to the glow plug. Such a step is generally called afterglow or afterglow step. Before starting the engine, the resistance heater is maintained at a sufficiently high temperature so that the engine can be started at any time.After starting the engine, warming up of the combustion chamber of the engine is promoted and generation of diesel knock is suppressed. It is possible to prevent noise, generation of white smoke, emission of HC components, and the like.
For example, Patent Literature 1 and Patent Literature 2 may be cited as literatures related to such a technique.

Further, immediately after the transition from the pre-glow step to the after-glow step, the phenomenon that the temperature of the resistance heater once falls below the second target temperature to be maintained, or the key switch is moved to the start position during the after-glow step. In this case, when engine cranking is started, there is also a phenomenon that the temperature of the resistance heater falls below the second target temperature to be maintained.
In order to cope with these, the pre-glow step, transition glow step, cranking glow step and post-start-up glow step are included, and the power to be supplied to the glow plug during the cranking glow step is made larger than before. The technique of Patent Document 3 that controls the above is also known.

Japanese Patent Laid-Open No. 56-129763 JP 60-67775 A Japanese Patent Laid-Open No. 2004-232907

  However, under a low temperature environment, even if the engine is started by cranking, misfire may occur in some cylinders, the rotational speed may not be stable, and so-called rough idle in which large vibrations occur in the engine may continue for a long time. If this state continues, in addition to causing discomfort to the driver and the like due to vibration and noise, problems such as discharge of unburned gas also occur.

On the other hand, in order to reduce such a phenomenon, after the cranking is finished (the period of the glow step after starting), the temperature of the resistance heater of the glow plug is kept high, and ignition is supported to suppress misfire. However, if the temperature of the resistance heater is kept high, the durability of the resistance heater is reduced.
The present invention has been made in view of such a problem, and it is possible to reduce a period in which the rotational speed is unstable after the engine is started, and further, glow plug energization considering the durability of the glow plug (resistance heater). It is an object to provide a control device and a glow plug energization control method.

The solution is a glow plug energization control device for controlling energization from a battery to a resistance heating heater of a glow plug installed in the engine during a period before and after starting the engine, after the engine cranking is started. And a post-start glow means for energizing the glow plug based on start information indicating that the engine has started. The post-start glow means includes a stability evaluation means for evaluating the rotational stability of the engine, When it is evaluated that rotational stability equal to or higher than the level is obtained, the resistance heating heater is set to a predetermined first.
When the low temperature start glow means that controls energization with the control pattern after start, and when the resistance heating heater is energized and controlled by the low temperature start glow means when it is evaluated that the predetermined level of rotational stability is not obtained The temperature of the resistance heater becomes higher than the second
High temperature post-start glow means for controlling energization with a post-start control pattern, and the stability evaluation means uses the rotational speed information relating to the rotational speed of the engine at each time point acquired from outside by communication, and The rotational speed stability evaluating means for evaluating rotational stability, the rotational speed stability evaluating means using the rotational speed information, a moving standard deviation calculating means for calculating a moving standard deviation of the rotational speed, and the moving standard deviation Is a glow plug energization control device including determination means for determining that the predetermined level of rotational stability is not obtained when the value is greater than a predetermined value .

In the glow plug energization control device of the present invention, after starting the engine, the post-start glow means energizes the resistance heater of the glow plug to heat it. As a result, the rotational stability of the engine immediately after starting can be improved, and the generation of noise and white smoke, the emission of HC components, etc. can be suppressed.
Specifically, when the rotational stability of the engine has reached a predetermined level, the after-start glow means is a low temperature start-up glow means that performs energization control according to the first after-start control pattern, and the resistance of the glow plug Set the heater to a relatively low temperature. Since the engine rotation stability has reached a certain level, in addition to assisting ignition, knock noise, white smoke, and emission of HC components can be suppressed without increasing the temperature of the resistance heater of the glow plug. Because it is possible. Further, since the period during which the resistance heater of the glow plug is maintained at a high temperature is shortened, the durability of the glow plug (resistance heater) is improved, and the glow plug can be used for a longer period of time. . Also, unnecessary power (energy) consumption can be suppressed.

  On the other hand, when the rotational stability of the engine does not reach a predetermined level (in the case of rough idling), the second post-starting control pattern is used in the glow means after high temperature start, compared to the case using the glow means after low temperature start, Increase the temperature of the resistance heater. As a result, even when the engine is started, such as when starting at low temperatures, the rotational stability level tends to be low (prone to rough idling) even if the engine starts. Even when it takes time to stabilize, the rotational stability of the engine can be improved early by increasing the temperature of the resistance heater and assisting ignition. Thereby, unpleasant vibration and noise of the engine can be converged at an early stage, and the discharge of unburned gas can be suppressed.

The start information may be information that can be used to determine that the engine has started. For example, information that the engine speed has exceeded a predetermined speed, information on whether or not the alternator is generating power, information on whether or not the generated voltage, generated power, etc. have exceeded a predetermined value, the driver Information indicating that the key switch has been turned from start to on. A combination of these can also be used as start information for determining engine start.
Further, the start timing of the post-start glow means may be determined based on the start information after the start of cranking. Specifically, after i) starting the engine and before the end of cranking, ii) after starting the engine and at the end of cranking (when the driver turns the key switch on, etc.) Iii) After the engine starts, after cranking ends (when the cranking instruction is stopped, such as when the driver turns the key switch back on), etc. Timing is mentioned.

  In addition, as a method for evaluating the rotational stability of the engine, any method that can evaluate the rotational stability of the engine in real time can be employed. For example, using the rotation speed information about the engine rotation speed at each time point, the difference between the current engine rotation speed and the previous engine rotation speed (rotation speed difference value) at each time point is calculated. If this difference value falls below a predetermined value over a certain period, it is determined that the engine speed is stable. If the difference value may exceed a predetermined value, the engine speed is not stable. There is a method to judge. Further, for example, using the moving standard deviation value of the engine speed at each time point, and when the moving standard deviation value is below a predetermined value, it is determined that the engine speed is stable, and the predetermined value is set to If it exceeds, a method of determining that the engine speed is not stable can be cited. The moving standard deviation value refers to a standard deviation value calculated for a group of rotational speeds obtained by accumulating the engine rotational speed at each time point a predetermined number of times (for example, 50 times).

The rotational speed information is information related to the rotational speed of the engine, and includes the rotational speed of the engine at each time point determined by the ECU or the like from the output of the rotational speed sensor, the crank angle sensor, or the like. Moreover, the moving average value of the rotation speed obtained by accumulating the rotation speed of the engine at each time point for a predetermined number of times is also mentioned. As for the rotational speed information, the rotational speed information transmitted from the ECU or the like is preferably received by the glow plug energization control device through communication. In addition, the output of the crank angle sensor or the like may be directly and periodically taken into the glow plug energization control device to determine the rotational speed.
In addition, regarding the evaluation of the rotational stability of the engine, the magnitude of vibration that occurs when the rotational stability of the engine is low (such as when some cylinders misfire), the specific frequency components included in the vibration, etc. A method of detecting and evaluating can also be adopted.

  Further, the glow means after the high temperature start is a means for controlling the temperature of the resistance heating heater of the glow plug by the second post start control pattern in which the temperature of the glow plug is set higher than in the case of the glow means after the low temperature start in the first start control pattern. Any means may be used as long as it is an energization control so that the electric power supplied to the resistance heater is increased. For example, specifically, when the duty ratio control (PWM control) is performed for the electric power supplied to the resistance heater, the glow plug has a duty ratio Da2 that is larger than the duty ratio Da1 when the low temperature start glow means is used. There is a means for PWM control of the energization to the.

In the glow plug energization control device of the present invention, the rotation speed stability evaluation means for evaluating the rotation stability of the engine using the rotation speed information relating to the rotation speed of the engine is used as the stability evaluation means. If the rotational speed information related to the rotational speed of the engine is used to evaluate the rotational stability, the rotational stability can be evaluated directly, so that it can be evaluated reliably and accurately.
Moreover, in the glow plug energization control device of the present invention, the rotational speed information is obtained from outside by communication. In many cases, an ECU or the like obtains information indicating the number of revolutions of the engine at each time point from the output of a revolution number sensor, a crank angle sensor, or the like. Therefore, if information already obtained by the ECU or the like is obtained as communication speed information from the ECU or the like as described above, it can be easily obtained. Further, the processing by the glow plug energization control device is easy.
The rotational speed information acquired from the outside includes the engine rotational speed at each time point and a moving average value of the rotational speed obtained by accumulating the engine rotational speed at each time point a predetermined number of times.

  In the glow plug energization control device of the present invention, the moving standard deviation calculating means calculates the moving standard deviation of the rotational speed using the rotational speed information. When the moving standard deviation of the rotational speed is large, it indicates that the rotational speed value at each time point varies with time, that is, the rotational stability of the engine is low. Therefore, by using this moving standard deviation, it is possible to appropriately evaluate whether or not the rotational stability has reached a predetermined level in the determination means.

Although the rotational stability can be evaluated using the difference value of the rotational speed (difference between the current rotational speed and the previous rotational speed), the difference value is Since there is a tendency to change drastically with time (up and down), it is difficult to properly evaluate the rotational stability.
On the other hand, the moving standard deviation is calculated by using a large number (for example, 50) of past rotational speeds, so that the moving standard deviation does not change suddenly when the rotational speed temporarily changes. On the other hand, when the misfire of each cylinder decreases and the engine rotation becomes stable, the moving standard deviation shows a tendency to gradually decrease, so that it is more suitable as an index for evaluating the rotation stability.

  In calculating the moving standard deviation, the number of rotation speed information to be used depends on the frequency of the rotation speed information received from the outside by the glow plug energization control device, but a period of about 0.3 seconds to 5.0 seconds. It is good to make it the number which can reflect the rotation speed information over. For example, when the rotation speed information is obtained every 10 msec, the moving standard deviation may be calculated using the rotation speed information of 30 to 500 pieces (0.3 seconds to 5.0 seconds). If it is too short, the moving standard deviation value may not be stable. On the other hand, if the length is too long, the change in the rotational speed is not easily reflected, and appropriate control is difficult to perform.

  In addition, after starting the cranking, before and after starting the engine, the engine speed changes suddenly from a very low speed due to cranking to a value of, for example, several hundred rpm. For this reason, there is a possibility that a useful value cannot be obtained even if the movement standard deviation is calculated. Therefore, the rotational speed information obtained within a predetermined period (for example, several seconds) after the engine has started, such as when the rotational speed of the engine exceeds a predetermined value (for example, several hundred rpm) is used to calculate the moving standard deviation. It is preferable to perform a process that is not used.

Further, in the above glow plug energization control device, the low temperature start glow means has a temperature of the resistance heating heater as a first temperature.
A glow plug energization control device that controls energization of the resistance heater so as to reach and maintain the target temperature is preferable.

  In the glow plug energization control device of the present invention, when the stability evaluation means evaluates that the rotational stability of a predetermined level or more is obtained and the resistance heating heater is energized and controlled by the glow means after the low temperature start, the resistance heating The energization to the glow plug is controlled so that the temperature of the heater becomes the first target temperature and is maintained. This effectively promotes warm air in the combustion chamber of the engine, prevents generation of diesel knock, and suppresses generation of noise and white smoke, emission of HC components, and the like.

  Further, in the above glow plug energization control device, the low temperature start glow means calculates a duty ratio Da1 of a voltage waveform applied to the glow plug based on a resistance value of the resistance heater, and this duty A glow plug energization control device that PWM-controls the energization of the resistance heater according to the ratio Da1.

In the glow plug energization control device of the present invention, the glow means after the low temperature start calculates the duty ratio Da1 of the voltage waveform applied to the glow plug based on the resistance value of the resistance heating heater, thereby energizing the glow plug. PWM control is performed. The PWM control has an advantage that the input power to the glow plug can be easily adjusted by the duty ratio. Here, during the control period by the glow means after the cold start, the temperature of the resistance heating heater may decrease due to external factors such as combustion spray and swirl, so that the resistance heating heater is stably heated in anticipation of this. There is a need. On the other hand, the resistance value of the resistance heating heater during the control period by the glow means after the cold start is in a steady state corresponding to the temperature, that is, there is a correlation between the resistance value of the resistance heating heater and the temperature. If the duty ratio Da1 calculated based on the resistance value is used, the heater temperature can be more accurately set as the first target temperature and can be stably maintained.
If the duty ratio Da1 corresponding to each resistance value is determined in advance, the heater temperature can be controlled by a simple control mode.

  Furthermore, in the glow plug energization control device according to any one of the preceding two paragraphs, the glow means after the high temperature start has a temperature of the resistance heater that becomes a second target temperature higher than the first target temperature, In order to maintain this, a glow plug energization control device that controls energization of the resistance heater is preferably used.

  In the glow plug energization control device of the present invention, when the stability evaluation means evaluates that the rotational stability of a predetermined level or more is not obtained and the resistance heating heater is energized and controlled by the glow means after the high temperature start, the resistance heating The energization of the glow plug is controlled so that the heater temperature becomes a second target temperature higher than the first target temperature and is maintained. Thus, even after the engine is started, the temperature of the resistance heating heater is set to the second target temperature that is higher, and is maintained. Thus, even in a state where the rotational stability of the engine is low, the warming of the engine combustion chamber is surely promoted. By assisting ignition, misfire can be suppressed, generation of diesel knock can be prevented, generation of noise and white smoke, emission of HC components, and the like can be suppressed.

  Further, in the above glow plug energization control device, the high temperature post-start glow means calculates a duty ratio Da2 of a voltage waveform applied to the glow plug based on the resistance value of the resistance heater, and this duty A glow plug energization control device that PWM-controls energization of the resistance heater according to the ratio Da2.

In the glow plug energization control device of the present invention, the glow means after the high temperature start calculates the duty ratio Da2 of the voltage waveform applied to the glow plug based on the resistance value of the resistance heater, thereby energizing the glow plug. PWM control is performed. The PWM control has an advantage that the input power to the glow plug can be easily adjusted by the duty ratio. The resistance value of the resistance heating heater during the control period by the glow means after the high temperature start is in a steady state corresponding to the temperature, that is, there is a correlation between the resistance value of the resistance heating heater and the temperature. If the duty ratio Da2 calculated based on the resistance value is used, the heater temperature can be more accurately set as the second target temperature and can be stably maintained.
If the duty ratio Da2 corresponding to each resistance value is determined in advance, the heater temperature can be controlled by a simple control mode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a glow plug energization control system 100 including a glow plug energization control apparatus 101 of the present invention will be described with reference to FIG. The glow plug energization control system 100 includes a glow plug energization control device 101, a battery BT, a key switch KSW, an engine control unit 201 (hereinafter also referred to as ECU), and an alternator 211. .

  Among these, the glow plug energization control device 101 indicated by a broken line in FIG. 1 includes a main control unit 111, n switching elements 1051 to 105 n, a power supply circuit 103, and interface circuits 104 and 106. Among these, the main control unit 111 includes a microcomputer (not shown) including a CPU, ROM, RAM, and an A / D converter. The power supply circuit 103 also receives power from the battery BT via the key switch KSW and the terminal 101B, and supplies a stable operating voltage for signal processing to the main control unit 111. Specifically, when the driver sets the key switch KSW to the on position and the start position, power is supplied from the battery BT to the main control unit 111 through the power supply circuit 103, and the main control unit 111 operates. On the other hand, when the key switch KSW is set to the OFF position, the power supply to the power supply circuit 103 and the main control unit 111 is interrupted, and the main control unit 111 stops its operation.

Moreover, each switching element 1051-105n is a switching element containing power MOSFET in this embodiment. Specifically, each of the switching elements 1051 to 105n is a FET with a current detection function (PROFET (registered trademark) manufactured by Infineon Technologies AG) that can output the magnitude of the current flowing between its drain-source as a current signal. . Current signals are output from the switching elements 1051 to 105n to the main control unit 111, respectively. Specifically, the switching elements 1051 to 105n are supplied with power from the battery BT via the battery terminal 101F to the drain of the FET. The source of each FET is connected to n glow plugs GP1 to GPn via the glow terminals 101G1 to 101Gn, respectively. In addition, a switching signal from the main control unit 111 is input to the gate of each FET among the switching elements 1051 to 105n. Therefore, switching control of the current flowing between the drain and source by the switching signal from the main control unit 111, and hence ON / OFF control of energization to each of the glow plugs GP1 to GPn is possible.

Further, the voltage of the glow terminals 101G1 to 101Gn, and hence the applied voltages V1 to Vn to the glow plugs GP1 to GPn, are input to the main control unit 111, respectively. Therefore, the main control unit 111 can know the voltages V1 to Vn applied to the glow plugs GP1 to GPn and the magnitudes of the currents I1 to In flowing through the glow plugs GP1 to GPn. That is, it is possible to know the magnitude of the electric power supplied to each of the glow plugs GP1 to GPn.
The applied voltages V1 to Vn applied to the glow plugs GP1 to GPn and the magnitudes of the energizing currents I1 to In flowing through the glow plugs GP1 to GPn input to the main control unit 111 are digitized by an A / D converter (not shown). A microcomputer (not shown) in the main control unit 111 performs processing according to a processing program to be described later.

Further, in the glow plug energization control device 101, the main control unit 111 can know whether or not the driver has set the key switch KSW to the start position through the interface circuit 104.
Further, the main control unit 111 can communicate with an external ECU 201 via the interface circuit 106, and periodically transmits data on the engine speed N (not shown) separately acquired by the ECU 201 from the ECU 201. Is receiving. The main control unit 111 is configured to be able to receive the drive signal of the alternator 211 via the interface circuit 106.

  Next, the structure of the glow plug GP (GP1 to GPn) that is energized and controlled by the glow plug energization control device 100 will be described. FIG. 2 is a partially broken sectional view of the glow plug GP. FIG. 3 is an explanatory view showing a state where the glow plug GP is installed in the engine block EB of the diesel engine. The glow plug GP includes a sheathed heater 2 configured as a resistance heating heater and a cylindrical metal shell 3 disposed on the outside thereof. As shown in FIG. 3, the sheathed heater 2 is arranged inside a sheathed tube 11 whose tip is closed, and a plurality of, in this embodiment, two resistance wire coils, that is, on the tip side (right side in the drawing). The heating coil 21 and the control coil 23 connected in series at the rear end thereof are enclosed together with magnesia powder 27 as an insulating material. As shown in FIG. 2, in the sheath tube 11, the main body portion 11 a that houses the heating coil 21 and the control coil 23 has a distal end side (downward in FIG. 2) protruding from the metal shell 3. As shown in FIG. 3, the heat generating coil 21 is electrically connected to the sheath tube 11 at the tip, but the outer periphery of the heat generating coil 21 and the control coil 23 and the inner peripheral surface of the sheath tube 11 are interposed by the magnesia powder 27. It is in the state insulated by. Moreover, the base end side (upward in FIG. 2) of the sheath tube 11 is a large-diameter portion 11b having a diameter larger than that of the main body portion 11a.

  The heating coil 21 has, for example, an electric specific resistance R20 at 20 ° C. of 80 μΩ · cm to 200 μΩ · cm and an electric specific resistance at 1000 ° C. of R1000 of R1000 / R20 of 0.8 to 3 The material, specifically, Fe—Cr alloy or Ni—Cr alloy is used. On the other hand, the control coil 23 has a ratio R1000 / R20 of 6 to 20 when the electrical specific resistance R20 at 20 ° C. is 5 μΩ · cm to 20 μΩ · cm and the electrical specific resistance at 1000 ° C. is R1000. It is made of a material, specifically, Ni, Co—Fe alloy, Co—Ni—Fe alloy or the like.

  As shown in FIG. 3, a rod-shaped energizing terminal shaft 13 is inserted into the sheath tube 11 from the base end side (left side in FIG. 3), and its tip is welded to the rear end of the control coil 23. Etc. are connected. On the other hand, as shown in FIG. 2, a male screw portion 13 a is formed at the rear end portion of the energizing terminal shaft 13. The metal shell 3 has a cylindrical shape having a through hole 4 penetrating in the axial direction, and the distal end side of the sheath tube 11 protrudes from the tip 3b of the metal shell 3 by a predetermined length in the through hole 4. Thus, the sheathed heater 2 is inserted and fixed. Further, on the outer peripheral surface of the metal shell 3, a hexagonal cross-section tool engaging portion 9 is formed for engaging a tool such as a torque wrench when the glow plug GP is attached to the diesel engine (engine block EB). A mounting screw portion 7 for mounting is formed on the tip side (downward in the figure).

  The through hole 4 of the metal shell 3 includes a relatively small diameter small diameter portion 4a located on the distal end opening end 3b side from which the sheath tube 11 protrudes, and a large diameter portion 4b following the base end side (upward in FIG. 2). And a counterbore 4c reaching the base end 3a of the metal shell 3. Among these, the large diameter part 11b of the sheath tube 11 is press-fitted and fixed to the small diameter part 4a. On the other hand, a rubber O-ring 15 inserted through the energizing terminal shaft 13 and a ring-shaped insulating bush 16 (for example, nylon) are fitted into the counterbore 4c of the through-hole 4. Further, on the base end side (upward in the drawing), a pressing ring 17 for preventing the insulation bush 16 from falling off is attached to the energizing terminal shaft 13. The holding ring 17 is reduced in diameter by caulking and fixed to the energizing terminal shaft 13. Further, in this glow plug GP, in order to increase the coupling force with the pressing ring 17, a portion of the energizing terminal shaft 13 located inside the pressing ring 17 is a knurled portion 13b whose surface is knurled. Yes. In the energizing terminal shaft 13, a nut 19 for fixing the terminal of the energizing cable to the energizing terminal shaft 13 is screwed into the base end side (upward in the drawing) from the knurled portion 13 b.

  As shown in FIG. 3, the glow plug GP is mounted in a plug hole HP provided in the engine block EB of the diesel engine by a mounting screw portion 7 of the metal shell 3. Thereby, the part at the front end side of the main body part 11a of the sheath tube 11 is arranged in a form protruding in the engine combustion chamber CR by a certain length. For example, in the present embodiment shown in FIG. 3, in the sheathed heater 2, the entire heating coil 21 and the control coil 23 are disposed in the engine combustion chamber CR.

Next, energization control of the glow plug GP by the glow plug energization control system 100 (glow plug energization control device 101) will be described with reference to the flowcharts shown in FIGS. 4 to 13 and the graphs of FIG.
The glow plug energization control device 101 performs the following energization control. That is, when the driver (operator) turns the key switch KSW from the off position to the on position, the main control unit from the battery BT via the key switch KSW, the power supply terminal 101B, and the power supply circuit 103 as described above. A driving voltage is applied to 111. Thereby, the main control unit 111 starts to operate in a predetermined procedure, and the energization control described below is performed for each of the glow plugs GP1 to GPn according to a program stored in advance.

That is, first, a pre-glow step controlled by the pre-glow means is executed. That is, the voltage of the battery BT is directly applied to the glow plug GP to raise the temperature of the sheathed heater 2 in a short time to the pre-glow target temperature (for example, TG = 1000 ° C.). Thereafter, the process proceeds to a transition glow step controlled by the transition glow means. That is, the energization to the glow plug GP is PWM-controlled based on the applied voltage V1 of the glow plug GP and the like, and the drop in the temperature TG of the sheathed heater 2 is suppressed. When the operator sets the key switch KSW to the start position during this transition glow step, the engine starts cranking and shifts to the cranking glow step controlled by the cranking glow means. That is, the energization to the glow plug GP is PWM-controlled based on the applied voltage V1 of the glow plug GP during cranking, etc., and the drop in the temperature TG of the sheathed heater 2 during this period is suppressed, and the engine startability is improved. Improve. Further, after the engine is started, the process proceeds to a post-start glow step controlled by the post-start glow means. Specifically, the rotational stability of the engine after starting is evaluated, and when the rotational stability has reached a certain level, a low temperature starting glow step is executed by the low temperature starting glow means, and a predetermined time ( For example, for 180 seconds, the temperature TG of the sheathed heater 2 is maintained at the first target temperature (eg, TG = 900 ° C.) after starting. On the other hand, if the rotational stability has not reached a certain level, a glow step after the high temperature start is executed by the glow means after the high temperature start, and the temperature TG of the sheathed heater 2 is started until the rotational stability reaches a certain level. Then, a second target temperature after start (for example, TG = 1000 ° C.) that is higher than the first target temperature is set, and this is maintained, misfire is prevented, and engine rotation is stabilized early.
In this embodiment, the first target temperature after start corresponds to the first target temperature of the present invention, and the second target temperature after start corresponds to the second target temperature of the present invention.

  The details of the energization control will be described below. As shown in FIG. 4, when the driver sets the key switch KSW to the ON position, 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 GP 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, 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 has been set to the start position), a post-start glow flag (in the post-start glow step) And a start flag (a flag indicating that the engine has started) are each cleared.

  Next, in step S2, as shown in FIG. 1, voltage values V1 to Vn applied to the glow plug GP through the glow terminals 101G1 to 101Gn and current values passed to the glow plugs GP through the switching elements 1051 to 105n. I1 to In are taken into the main control unit 111, respectively. Then, current resistance values R1 to Rn of each sheathed heater 2 are calculated from these voltage values V1 to Vn and current values I1 to In, respectively.

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

  In step S32, a start signal indicating that the key switch KSW has been set to the start position is taken in through the interface circuit 104. 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. The reason for being continuous for 0.1 sec is to eliminate erroneous input of the start signal due to noise or the like. 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, that is, if the input of the start signal is not on continuously for 0.1 sec (when the key switch KSW is not at the start position), the process proceeds to step S35. In step S35, it is determined whether or not the start signal input is continuously off for 0.1 sec, specifically, whether or not the start signal input is off for 8 consecutive periods. That is, it is determined whether or not the key switch KSW is not at the start position. If YES, that is, if the start signal input is OFF for 0.1 seconds continuously (when the key switch KSW is not in the start position, that is, in the ON position), the start signal flag is cleared in step S36. Return to the main routine. On the other hand, if NO, that is, if the start signal input is not OFF continuously for 0.1 sec, the process directly returns to the main routine.

Next, in step S4 of the main routine of FIG. 4, a duty ratio Dh in PWM control during the transition glow step and a duty ratio Dk in PWM control during the cranking glow step are calculated. Specifically, for the transition glow step, the duty ratio Dh of the pulse waveform applied to the glow plug GP is calculated based on the voltage values V1 to Vn applied to the glow plug GP. Similarly, regarding the cranking glow step, the duty ratio Dk of the pulse waveform applied to the glow plug GP is calculated based on the voltage value V1 applied to the glow plug GP and the like.
Each time step S4 is executed, these may be calculated using a calculation formula. For example, a table showing the relationship between the voltage value V1 applied to the glow plug GP and the duty ratio Dh or Dk. And the duty ratios Dh and Dk may be determined with reference to the above.

The duty ratios Dk and Dh are such that the voltage value applied to the glow plug GP during the transition glow step is the same as the voltage value applied to the glow plug GP during the cranking glow step. Assuming that, the calculation formula or table is adjusted so as to be larger than the duty ratio Dh calculated in the transition glow step.
Thereby, it can suppress that the temperature of the sheathed heater 2 falls after transfering from a transition glow step to a cranking glow step.

Next, in step S5, the duty ratio Da1 in the PWM control during the low temperature start glow step in the post start start glow step is calculated. That is, the process proceeds to a subroutine shown in FIG. Here, first, in step S51, an error ΔR1 from the target value of the resistance value of the sheathed heater 2 is calculated. Specifically, when the current resistance value of the sheathed heater 2 is R, and the resistance value when the sheathed heater 2 reaches the first target temperature (for example, TG = 900 ° C.) after starting is Rt1, the error of the resistance value ΔR1 is calculated by ΔR = Rt1-R. Next, it progresses to step S52 and the control effective voltage value Vc is calculated. Specifically, the control effective voltage value Vc is calculated using an equation of Vc = K ₀ + K ₁ ΔR1 + K ₂ ∫ΔR1dt. K ₀ , K ₁ , K ₂ are constants, and K ₀ , K ₁ , K ₂ > 0. Subsequently, the process proceeds to step S53, and the duty ratio Da1 is calculated. Specifically, the duty ratio Da1, calculated according Da1 = Vc ² / Vb ^2. Note that Vb is the voltage values V1 to Vn of each glow plug GP captured in step S2. Then return to the main routine.

Next, in step S6, the duty ratio Da2 in the PWM control during the high temperature start glow step in the post start start glow step is calculated. That is, the process proceeds to a subroutine shown in FIG. Here, first, in step S61, an error ΔR2 from the target value of the resistance value of the sheathed heater 2 is calculated. Specifically, the current resistance value of the sheathed heater 2 is R, and the resistance value when the sheathed heater 2 reaches a second post-starting second target temperature (eg, TG = 1000 ° C.) higher than the first target temperature after starting is Rt2. Then, the resistance value error ΔR2 is calculated by ΔR = Rt2-R. Next, it progresses to step S62 and the control effective voltage value Vd is calculated. Specifically, the control effective voltage value Vd is calculated using an equation of Vd = K ₃ + K ₄ ΔR2 + K ₅ ∫ΔR2dt. K ₃ , K ₄ , and K ₅ are constants, and K ₃ , K ₄ , and K ₅ > 0. Then, it progresses to step S63 and calculates duty ratio Da2. Specifically, the duty ratio Da2, calculated according Da2 = Vd ² / Vb ^2. Then return to the main routine.

  Next, in step S7, a moving standard deviation σa of the engine speed N is calculated. Specifically, the subroutine shown in FIG. 8 is executed. First, in step S71, information on the engine speed N is acquired from the ECU 201 through the interface circuit 106. In this embodiment, the data of the current rotational speed N obtained by the ECU and the output of a crank angle sensor (not shown) that outputs a signal corresponding to the rotational speed N of the engine is received from this ECU. In step S72, it is determined whether or not a start flag indicating that the engine has started is set. If YES, that is, if the engine is started, the timer is started in step S73, and then the process proceeds to step S74. On the other hand, if NO, that is, if the engine has not yet been started, step S73 is skipped and the process proceeds to step S74.

In step S74, it is determined whether 2 seconds or more have elapsed since the timer started. If YES, that is, if 2 seconds or more have elapsed since the engine was started, the process proceeds to step S75, the data of the current engine speed N received from the ECU 201 is stored, and then the process proceeds to step S76. On the other hand, if NO, that is, if the predetermined time has not elapsed since the engine start, step S75 is skipped and the process proceeds to step S76.
Before and after starting the engine, the rotational speed N increases rapidly from a very low speed cranking to several hundred rpm. Immediately after starting, the rotational speed N itself is not stable. For this reason, if the standard deviation σa of the rotational speed N is calculated for the period including the period before and after the engine start, it is predicted that it will be an extremely large value. Therefore, immediately after the engine is started, more specifically, even if the rotation speed data is received from the ECU 201 until an appropriate period of about 2 seconds elapses after YES is determined in step S92 described later. It is because it is preferable not to use.

In step S76, it is determined whether or not 50 pieces of stored rotational speed N data have been accumulated. If YES here, that is, if 50 rotation speed data are accumulated, the process proceeds to step S77, and the moving standard deviation σa is calculated. In step S78, the oldest rotation speed data (acquired for 50 times in the past) is deleted from the stored 50 rotation speed data. This is because new rotational speed data is stored next time. Thereafter, the process returns to the main routine.
On the other hand, if NO is determined in step S76, that is, if the stored rotational speed data is less than 50 (including the case where the storage is not performed), steps S77 and S78 are skipped, Return to the main routine.

The moving standard deviation σa in step S76 is calculated as follows. Of the rotation speed N data stored in step S75, the current (latest) rotation speed data is N0, the previous rotation speed data acquired once (1 time in the past) is N1, and the rotation speed data acquired 49 times in the past. Is N49 and the moving average value is DA, the moving standard deviation σa is obtained by the following equation (1).
σa = √ [{(N0−DA) ² + (N1−DA) ² +... + (N49−DA) ² } / 50] (1)
The moving average value DA is given by the following formula (2).
DA = (N0 + N1 + N2 + ... + N49) / 50 (2)

  Next, in step S8, it is determined whether or not cranking is currently in progress. That is, it is determined whether or not the start signal flag is set. If YES, that is, if cranking is in progress (when the start signal input flag is set), the process proceeds to a subroutine for cranking glow processing in step S9. On the other hand, if NO, the process proceeds to step SB.

  In step S9, the cranking glow process shown in FIG. 9 is performed. First, in step S91, cranking energization is turned on. Specifically, the energization to the glow plug GP is PWM controlled with the duty ratio Dk calculated in step S4. In step S92, it is determined whether or not the engine has been started. Specifically, when the engine is started, the rotational speed N increases to several hundreds rpm, so that the rotational speed data obtained from the ECU 201 is a value equal to or higher than a predetermined threshold value (for example, Nth = 800 rpm). If it is determined that the engine has been started, it is determined that the engine has started. If YES (engine started), a start flag indicating that the engine has started is set in step S93, and the process returns to the main routine. If NO (NO in step S92), the process skips step S93 and returns to the main routine.

  On the other hand, if NO is determined in step S8 and the process proceeds to step SB, it is determined whether or not the alternator 211 is in operation. Specifically, the output of the alternator 211 is acquired through the interface circuit 106. If YES, that is, if the engine is started and the alternator 211 is in operation, the process proceeds to a glow step after starting. Specifically, first, the process proceeds to step SC, and it is determined whether or not the moving standard deviation σa has been calculated. In the moving speed standard deviation calculation subroutine of the rotational speed in step S7, as already explained, the moving standard deviation σa is calculated unless 2 seconds have passed since the engine started and if 50 speed data are not stored. Not. Therefore, when the moving standard deviation σa is calculated, it is considered that a certain amount of time has elapsed from the start of the engine and the engine rotational stability can be evaluated.

Therefore, in the case of YES at this step SC, the routine proceeds to step SD, where it is determined whether or not the moving standard deviation σa of the rotational speed N is larger than a predetermined threshold σth. If σa> σth (YES), the process proceeds to step SE to execute a glow processing subroutine after the high temperature start (see FIG. 10). This is because the moving standard deviation σa of the rotational speed N is still large, so the rotational stability of the engine is low, and it is considered that the engine is in a rough idle state due to misfiring in some cylinders.
On the other hand, if NO in step SD (σa ≦ σth), the process proceeds to step SF, and a low temperature start-up glow processing subroutine is executed (see FIG. 11). This is because the moving standard deviation σa of the rotational speed N is smaller than the threshold value σth, so that the rotational stability of the engine is high, and it is considered that each cylinder is properly ignited.

  In the glow processing subroutine after high temperature start in step SE shown in FIG. 10, first, in step SE1, whether or not the glow energization time after high temperature startup by this subroutine has passed a predetermined high temperature maintenance time (for example, 180 seconds). Determine whether. Here, if NO, that is, if the predetermined high temperature maintenance time has not yet elapsed since the start of glow energization after the high temperature start, the process proceeds to step SE2. In step SE2, glow energization after high temperature start is turned on, and a post-start glow flag is set. The glow energization after the high temperature start is performed by PWM control of the energization to the glow plug GP with the duty ratio Da2 calculated in step S6, and the temperature of the sheathed heater 2 is set as the second target temperature (eg TG = 1000 ° C.) after the start. maintain. Thereafter, the process returns to the main routine. As a result, if the rotational stability is low after engine startup (YES in step SD), or if only a short time (2.6 seconds or less) has elapsed after engine startup, this glow after high temperature startup Since the sheathed heater 2 is maintained at a relatively high temperature (for example, TG = 1000 ° C.) by energization, the sheathed heater is used even when misfiring occurs in some cylinders of the engine due to a low temperature environment and the engine becomes rough idle. Misfire is suppressed by the ignition assistance by 2 (glow plug GP). Therefore, the rotational speed N becomes stable at an early stage, and vibration, noise, and discharge of unburned gas due to the unstable rotational speed N can be suppressed. Since the value of the moving standard deviation σa calculated in step S7 becomes early as the rotational speed N becomes stable, after step NO determines NO, that is, σa ≦ σth, this step SE This subroutine is not executed, and the glow processing subroutine after the low temperature start in step SF is executed.

  On the other hand, if YES in step SE1, that is, if the high temperature maintenance time has elapsed, the process proceeds to step SE3, the glow energization after high temperature start is turned off, the post-start glow flag is cleared, and the process returns to the main routine. If the value of the moving standard deviation σa does not decrease so much even after the high temperature maintenance time has elapsed (σa ≦ σth is not satisfied), the glow generated by maintaining the sheathed heater 2 at a high temperature (eg, TG = 1000 ° C.). This is because the conduction to the sheathed heater 2 is cut off in an appropriate period in consideration of the decrease in the life of the plug GP.

  Further, in the glow processing subroutine after low temperature start in step SF shown in FIG. 11, first, in step SF1, the time during which the start glow step is executed in steps SE and SF is a predetermined post-start glow time (for example, 180 seconds). ) Or not. If NO, that is, if a predetermined post-start-up glow time has not yet elapsed since the start of energization in step SE or step SF, the process proceeds to step SF2. In this step SF2, glow energization after low temperature start is turned on, and a post-start glow flag is set. In the glow energization after the low temperature start, the energization to the glow plug GP is PWM-controlled with the duty ratio Da1 calculated in step S5, and the temperature of the sheathed heater 2 is set to the first target after the start lower than the second target temperature after the start. This is maintained as a temperature (eg TG = 900 ° C.). Thereafter, the process returns to the main routine. As a result, even when the rotational stability is high after the engine is started, the sheathed heater 2 is maintained at a certain temperature (for example, TG = 900 ° C.) by glow energization after the low temperature start. By preventing misfire in the cylinder and assisting combustion, the rotational speed N can be further stabilized and exhaust gas can be purified.

  On the other hand, if YES in step SF1, that is, if a predetermined post-startup glow time has elapsed since the start of energization in step SE or step SF, the process proceeds to step SF3 to turn off the glow energization after the low temperature start and start Clear the rear glow flag and return to the main routine. Since a predetermined post-start glow time has elapsed after the engine is started, it is considered that ignition assistance, combustion assistance, etc. by the glow plug GP are no longer necessary. On the other hand, in consideration of a decrease in the life of the glow plug GP and power consumption caused by maintaining the sheathed heater 2 at a high temperature (eg, TG = 900 ° C.), the conduction to the sheathed heater 2 is interrupted in an appropriate period. is there.

  By the way, if NO in step SB, that is, if the alternator 211 has not yet been activated, the process proceeds to a pre-glow processing subroutine of step SG (see FIG. 12). Here, first, in step SG1, it is determined whether or not a pre-glow step is in progress, specifically, whether or not a pre-glow flag is set. Here, in the case of YES, the process proceeds to step SG2, and using the current values I1 to In and voltage values V1 to Vn acquired in step S2, one cycle from the previous calculation in step SG2 to the current calculation is performed. The amount of power (Gw1) input to the glow plug GP during the minute period is calculated. Next, it progresses to step SG3 and the integrated electric energy (Gw) of the glow plug GP is calculated. That is, the newly integrated power amount Gw1 is added to the previous integrated power amount Gw to obtain a new integrated power amount Gw.

Next, in step SG4, it is determined whether or not the integrated power amount Gw has exceeded the target input amount of power corresponding to the pre-glow target temperature (for example, TG = 1000 ° C.). Here, if NO, that is, if the integrated power amount Gw does not exceed the target input amount, the process proceeds to step SG6, where pre-glow energization is turned on. Specifically, continuous energization is performed to the glow plug GP. Thereafter, the process returns to the main routine. On the other hand, if YES in step SG4, that is, if the integrated power amount Gw exceeds the target input amount, the process proceeds to step SG5, where 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.
If NO in step SG1, that is, if it is determined that the pre-glow step is not being performed (when the pre-glow flag is not set), the process directly returns to the main routine.

  In step SA of the main routine, a transition glow processing subroutine shown in FIG. 13 is executed. Here, first, in step SA1, it is determined whether or not a cranking step is being performed or whether or not a post-starting glow step is being performed. Specifically, it is determined whether the start signal flag is set or whether the post-start glow flag is set. Here, when YES, that is, when cranking is in progress (when the start signal flag is set), or when after the start glow step (when the post-start glow flag is set) In step SA7, the transition glow energization is turned off, and the process returns to the main routine.

  On the other hand, if NO in step SA1, that is, if cranking is not in progress (the start signal flag is cleared) and the engine is not glowing after starting (the glowing flag after starting is also cleared), step Proceed to SA2. In step SA2, it is determined whether or not a transition glow time (a predetermined time since the transition glow step is started) has elapsed. If YES, that is, if the transition glow time has elapsed, the transition glow energization is turned off in step SA6, and the process returns to the main routine. On the other hand, if NO in step SA2, that is, if the transition glow time has not elapsed, the process proceeds to step SA3 to determine whether or not the pre-glow step is completed. Specifically, it is determined whether or not the pre-glow end flag is set. If NO, that is, if the pre-glow step has not ended (if the pre-glow end flag has been cleared), the process proceeds to step SA5 to turn off the transition glow energization and then return to the main routine. On the other hand, when the pre-glow step is completed (when the pre-glow end flag is set) in step SA3, the process proceeds to step SA4 to turn on transition glow energization and return to the main routine. In this transition glow energization, the energization to the glow plug GP is PWM-controlled based on the duty ratio Dh calculated in step S4 to suppress the temperature drop of the sheathed heater 2 immediately after the pre-glow step.

After executing step SA, the process proceeds to step SH to determine whether or not the time for one cycle (12.5 ms) has elapsed. If YES, that is, if 12.5 ms has elapsed, the process returns to step S2. On the other hand, if NO, that is, if 12.5 ms has not elapsed, step SH is repeated until it has elapsed.
The glow plug energization control device 101 of the present embodiment performs energization control of the glow plug GP (GP1 to GPn) as described above.

  In the glow plug energization control device 101 and its energization control of the present embodiment, a microcomputer (not shown) included in the main control unit 111 at the stage of executing each step respectively includes a post-starting glow means and a low-temperature starting glow control. It corresponds to each means of a means, a high temperature after-start glow means, a stability evaluation means, a rotational speed stability evaluation means, a moving standard deviation calculation means, and a judgment means. Specifically, steps S7, SD, SE, and SF correspond to the glow means after start, step SE corresponds to the glow means after high temperature start, and step SF corresponds to the glow means after cold start. Steps S7 and SD correspond to stability evaluation means and rotation speed stability evaluation means, step S7 corresponds to moving standard deviation calculation means, and step SD corresponds to determination means.

(Example)
Next, specific examples will be described. In this embodiment, in a low temperature environment (for example, in an environment of −20 ° C., −40 ° C., etc.), after the key switch KSW is turned on, after a while, the sheathed heater 2 is sufficiently heated, The energization control of the glow plug energization control system 100 (glow plug energization control device 101) when the switch KSW is set to the start position will be described. In the graph shown in FIG. 14, (a) is a temporal change in the temperature TG of the sheathed heater 2 of the glow plug GP, (b) a temporal change in the engine speed N, and (c) is a moving standard deviation σa of the engine speed N. The time change of is shown. Also, in each graph, the solid line indicates the case where the glow plug energization control device 101 of the present embodiment is used, while the broken line indicates that after the low temperature start without using the high temperature start glow step in the post start start glow step. A comparative example using only the glow step will be described.
In the following, an example is shown in which the glow plug GP is attached to an actual engine (displacement: 2.5 L, number of cylinders: 4 cylinders), and measurement is performed under an environment temperature of −20 ° C.

First, when the operator sets the key switch KSW to the ON position, the glow plug energization control device 101 is activated. First, in the pre-glow step from time t0 to t1, the sheathed heater 2 rises almost linearly to the pre-glow target temperature (TG = 1000 ° C. in this embodiment) by continuous energization control to the glow plug GP (FIG. 14 (FIG. 14 ( a)).
The description will be made along the above-described flowcharts (FIGS. 4 to 13). When the key switch KSW is turned on, the glow plug energization control device 101 is activated, step S1 is executed, and various flags, initial values, and the like are initialized. Subsequently, the process proceeds to step S2. At this stage, since the glow plug GP is not yet energized, the resistance value R1 such as the current value I1 is not calculated. Next, the process proceeds to a subroutine of step S3 (see FIG. 5). However, since NO is determined in step S31, the process directly returns to the main routine.

Next, the process proceeds to step S4, and the duty ratios Dh and Dk captured in step S2 are calculated. Further, the duty ratios Da1 and Da2 are calculated in the subroutines of steps S5 and S6. However, at this time, since the resistance value R1 and the like cannot be obtained in step S2, appropriate duty ratios Da1 and Da2 cannot be obtained.
Further, the process proceeds to step S7 (see FIG. 8), but in all of steps S72, S74, and S76, it is determined No, and the process returns to the main routine. Subsequently, the process proceeds to step S8, but since cranking is not being performed (because the start signal input flag is not set), it is determined NO and the process proceeds to step SB.

  Since the alternator 211 is not activated at this time, it is determined as NO in Step SB, and the process proceeds to a subroutine of Step SG (see FIG. 9). In step SG1, since the pre-glow flag is set, YES is determined and the process proceeds to step SG2. In step SG2, a power amount Gw1 is calculated. At this stage, since the glow plug GP is not yet energized, the power amount GW1 = 0. Then, the process proceeds to Step SG3. Since the integrated power amount Gw has an initial value of 0, Gw = 0 is set in step SG3. In step SG4, since the integrated power Gw has not reached the target input amount, it is determined as NO, and the process proceeds to step SG6. In step SG6, pre-glow energization is turned on. That is, after time t = t0, the switching element 1051 and the like are continuously turned on, and continuous energization is performed from the battery BT to the glow plug GP1 and the like. Thereafter, the process returns to the main routine.

  Thereafter, the process proceeds to a subroutine of step SA (see FIG. 13). Here, NO is determined in any of steps SA1, SA2, and SA3, and the process proceeds to step SA5. In step SA5, the transition glow energization is turned off (leaves off). Thereafter, the process returns to the main routine, proceeds to step SH, and returns to step S2 after 12.5 ms has elapsed.

  Next, in step S2, the voltage value V1 applied to the glow plug GP and the current value I1 flowing therethrough are taken in, and the current resistance value R1 of the sheathed heater 2 is calculated. Subsequently, the process proceeds to step S3, and similarly to the above, the process returns to the main routine through step S31. Next, duty ratios Dh and Dk are calculated in step S4. However, these are not used because they are in the pre-glow step. Next, the process proceeds to a subroutine of steps S5 and S6, and duty ratios Da1 and Da2 are calculated. However, these are not used because they are in the pre-glow step. Next, the process proceeds to step S7. In the same manner as described above, it is determined No in steps S72, S74, and S76, and the process returns to the main routine. Subsequently, the process proceeds to step S8, where NO is determined, and the process proceeds to step SB.

  Since the alternator is not activated even at this time, NO is determined in step SB, and the process proceeds to a subroutine of step SG (see FIG. 12). In step SG1, as described above, since the pre-glow step is in progress, it is determined YES and the process proceeds to step SG2. In step SG2, the amount of power GW1 input to the glow plug GP during one cycle is calculated using the voltage value V1 and the like acquired in step S2, the current value I1, and the like. Subsequently, in step SG3, the newly input power amount Gw1 is added to the previous integrated power amount Gw (here, 0) to obtain a new integrated power amount Gw. Next, in step SG4, since the integrated power amount Gw has not yet reached the target input amount, it is determined NO and the process proceeds to step SG6. In step SG6, 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 SA (see FIG. 13). In any of steps SA1, SA2 and SA3, NO is determined, and the process proceeds to step SA5. Subsequently, the transition glow energization is turned off. Thereafter, the process returns to the main routine, and after 12.5 ms has elapsed in step SH, the process returns to step S2.

  Thereafter, the above-described processing is repeated until the integrated power amount Gw becomes equal to or greater than the target input amount (until YES is determined in step SG4). If the integrated power amount Gw is equal to or greater than the target input amount, YES is determined in step SG4, so the process proceeds to step SG5 and the pre-glow energization is turned off. Also, the pre-glow flag is cleared and the pre-glow end flag is set. At this time, the temperature TG of the sheathed heater 2 has reached the pre-glow target temperature (TG = 1000 ° C.) as shown in FIG. Thereafter, the process returns to the main routine and proceeds to a subroutine of step SA (see FIG. 13). In steps SA1 and SA2, NO is determined as in the previous cycle. On the other hand, since the pre-glow end flag is set, unlike the previous time, YES is determined in step SA3 and the process proceeds to step SA4.

  In step SA4, the transition glow energization is turned on. Thereby, at time t1, the pre-glow step shifts to the transition glow step. In this transition glow step, as shown in FIG. 14A, during this step, the temperature TG of the sheathed heater 2 is maintained at 1000 ° C. to prevent temperature drop. As described above, this transition glow energization PWM-controls the energization of the glow plug GP based on the duty ratio Dh. Thereafter, the process returns to the main routine, proceeds to step S13, and after 12.5 ms has elapsed, returns to step S2.

Next, in step S2, the voltage value V1 and the like, the current value I1 and the like are taken in, and the resistance value R1 and the like of the glow plug GP are calculated. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 5). In step S31, since the pre-glow end flag is set and the post-start glow flag is cleared, it is determined YES and the process proceeds to step S32. Further, after the start signal is captured in step S32, the process proceeds to step S33. If the operator has not yet set the key switch KSW to the start position at this stage, there is no continuous start signal input. Is NO and the process proceeds to step S35. In this step S35, since the start signal input is turned off continuously for 8 periods, it is determined as YES. In step S36, the state signal flag is cleared.
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 to calculate the duty ratios Dh and Dk. Next, the process proceeds to a subroutine of steps S5 and S6, and duty ratios Da1 and Da2 are calculated. However, the duty ratios Dk, Da1, Da2 calculated here are not used. Further, even in the subroutine of step S7, the moving standard deviation σa of the engine speed is not calculated.

  Next, the process proceeds to step S8. Since cranking is not being performed at this time, it is determined as NO and the process proceeds to step SB. In step SB, since the alternator is not activated, it is determined as NO and the process proceeds to a subroutine of step SG (see FIG. 12). In step SG1, since the pre-glow flag has already been cleared, it is determined NO, unlike the previous time, and the routine returns directly to the main routine and proceeds to the subroutine of step SA (see FIG. 13). In steps SA1 and SA2, NO is determined as in the previous case, and the process proceeds to step SA3. In step SA3, since the pre-glow step has been completed, it is determined YES, the process proceeds to step SA4, and the transition glow energization is continuously turned on. Thereafter, the process returns to the main routine, and returns to step S2 via step SH.

  Thereafter, the driver sets the key switch KSW to the start position, so that a start signal is input for 0.1 second or longer, and the above processing is repeated until YES is determined in step S33 (see FIG. 5). Or, in step SA2, YES, that is, the above process is repeated until a predetermined transition glow time has elapsed (see FIG. 13). After the pre-glow, the driver was waiting for the key switch KSW to be the start position. However, if there is no operation by the driver after waiting for a certain period of time, the process proceeds to step SA6 and the transition glow energization is performed. Turn off. That is, the transition glow step ends. This is because it is considered that the driver has lost the intention to instruct the engine. Thereafter, the process returns to the main routine, and returns to step S2 via step SH.

On the other hand, if the key switch KSW is continuously set to the start position for 0.1 seconds before the transition glow time has elapsed, YES is determined in step S33, and the process proceeds to step S34 where the start signal flag is set. The Thereby, in the present embodiment, the transition glow step shifts to the cranking glow step at time t2 (see FIG. 14). In the subsequent cranking glow step, since a large current flows through the starting motor for cranking, the voltage of the battery BT (such as the voltage V1 applied to the glow plug GP) decreases, but the temperature TG (TG of the sheathed heater 2) (= 1000 ° C.), the energization to the glow plug GP is PWM-controlled with a larger duty ratio Dk than in the transition glow step. As a result, as shown in FIG. 14A, the drop in the temperature TG of the sheathed heater 2 does not occur although the sheathed heater 2 is cooled by the voltage drop of the battery BT due to cranking or the operation of the piston. Instead, the temperature TG is maintained.
At the same time, when the key switch KSW is set to the start position, the engine is cranked by a starter (not shown).

Next, in step S4, the duty ratios Dh and Dk are calculated. Next, the process proceeds to a subroutine of steps S5 and S6 (see FIGS. 6 and 7), and duty ratios Da1 and Da2 are calculated. However, the duty ratios Da1 and Da2 are not used. Further, even in the subroutine of step S7, the moving standard deviation σa of the engine speed is not calculated.
Next, in step S8, unlike the previous time, since the start signal flag is set at this stage, it is determined that cranking is in progress (YES), and the process proceeds to a subroutine of step S9 (see FIG. 9). Thus, cranking energization is turned on at time t2 (see FIG. 14). In this cranking step, the glow plug GP is PWM-controlled based on the duty ratio Dk. Thereafter, it is determined in step S92 whether or not the engine has been started. If the engine has not been started, the process returns to the main routine and proceeds to a subroutine of step SA (see FIG. 13). In step SA1, unlike the previous time, since the start signal flag is set, it is determined YES and the process proceeds to step SA7. In step SA7, the transition glow energization is continuously turned off, the process returns to the main routine, and returns to step S2 via step SH.

In step S2 again, the voltage value V1 and the like, the current value I1 and the like are taken in, and the resistance value R1 of the glow plug GP is calculated. Subsequently, the process proceeds to a subroutine of step S3 (see FIG. 5). In step S31, “YES” is determined, and the process proceeds to steps S32 and S33. In step S33, since the start signal is continuously input for 0.1 second or more, it is determined as YES, and the process proceeds to step S34, and the start signal flag is continuously set.
Thereafter, the above-described steps are repeated until the engine is started and the alternator is activated, and the driver returns the key switch KSW to the ON position to stop the cranking.

  On the other hand, when the engine is started and the rotational speed N rises above the threshold value Nth as shown in FIG. 14B, it is determined that the engine is started in step S92 of step S9 (see FIG. 9). A start flag is set (step S93). Further, the driver returns the key switch KSW from the start position to the on position. As a result, NO is determined in step S33, YES is determined in step S35, and the start signal flag is cleared in step S36 (see FIG. 5). Thereafter, the duty ratios Dh, Dk, Da1, Da2 are calculated in steps S4, S5, S6. Of these, only the duty ratio Da2 is used as described below.

  Next, the process proceeds to step S7 (see FIG. 8). Among these, since the start flag is set, if YES is determined in the step S72, the timer is started (step S73). However, since not much time has elapsed since the engine was started, steps S74 and S76 are both determined as NO, and the moving standard deviation σa of the engine speed N has not yet been calculated. Thereafter, NO is determined in step S8, YES is determined in step SB, and the process proceeds to step SC. As described above, since the moving standard deviation σa is not calculated in step S7, NO is determined in this step SC, and the process proceeds to a subroutine of step SE (see FIG. 10).

  Among these, in step SE1, it is determined whether or not a predetermined high temperature maintenance time has elapsed as described above. At this time, it is determined as NO, the process proceeds to step SE2, glow energization after high temperature start is turned on, and a post-start glow flag is set. As a result, at time t3, the cranking glow step shifts to the post-starting glow step. More specifically, the process proceeds to a glow step after a high temperature start. In the glow step after the high temperature start, the energization to the glow plug GP is PWM controlled with the duty ratio Da2, and the temperature TG of the sheathed heater 2 is set to the first target temperature after the start of the glow step after the low temperature start described later (in this embodiment). This is maintained as a second target temperature (TG = 1000 ° C. in the present embodiment) after starting that is higher than TG = 900 ° C.). As a result, as shown in FIG. 14A, the temperature TG of the sheath heater 2 maintains the same temperature as that of the cranking glow step (before time t3).

  Thereafter, in the subroutine of step SA (see FIG. 13), YES is determined in step SA1, and the transition glow energization is continuously turned off in step SA7. Further, the process returns to step S2 via step SH.

  Thereafter, the same steps as described above are repeated, and after the engine is started (time t3), 2 seconds have elapsed (YES in step S74), and 50 data of the rotational speed N are accumulated (YES in step S76). When the time elapses, the moving standard deviation σa of the engine speed N is calculated in step S77. Then, YES is determined in step SC, and it is determined in step SD whether or not the moving standard deviation σa is larger than a predetermined threshold value σth. If YES (σa> σth), the process proceeds to step SE to maintain the glow step after the high temperature start. That is, the temperature TG of the sheath heater 2 is maintained at the second target temperature after starting (TG = 1000 ° C. in this embodiment).

On the other hand, if NO (σa ≦ σth) is determined in step SD, the process proceeds to step SF, and at time t4, the process is switched to the low temperature start glow step.
In step SF shown in FIG. 11, not only the low temperature start glow step (step SF) but also the high temperature start glow step (step SE) and the post start start glow step in step SF1 It is determined whether or not a glow time (for example, 3 minutes) has elapsed after starting. At the time point (NO) when it has not yet elapsed, the glow energization after the cold start is turned on in step SF2. Further, the glowing flag after starting is set (the set is maintained).

In the glow step after the low temperature start, the energization to the glow plug GP is PWM controlled with the duty ratio Da1, and the temperature TG of the sheathed heater 2 is set to the second target temperature (in this embodiment, after the start of the glow step after the high temperature start). This is maintained as a first target temperature (TG = 900 ° C. in this embodiment) after starting that is lower than TG = 1000 ° C.). As a result, as shown in FIG. 14A, the temperature TG of the sheathed heater 2 is maintained at a temperature lower than that after the high temperature start glow step (before time t4) after time t4.
It is preferable to keep the temperature TG of the sheathed heater 2 high (for example, TG = 1000 ° C.) for assisting ignition of the engine. However, if the sheathed heater 2 is kept at a high temperature for a long time, the life of the heater 2 (glow plug GP) is reduced. This is also not preferable in that power consumption by the heater 2 increases. Therefore, in the present embodiment, when the moving standard deviation σa of the engine speed N is σa ≦ σth, the rotational stability of the engine is also improved, and the ignition of the engine can be achieved without setting the heater 2 at a very high temperature. On the other hand, the temperature TG of the heater 2 is relatively lowered in consideration of the life of the heater 2 and power consumption.

Thereafter, YES is determined in step SA1 in a subroutine of step SA (see FIG. 13), and the transition glow energization is continuously turned off in step SA7. Further, the process returns to step S2 via step SH.
Thereafter, the same steps as described above are repeated, and the temperature TG of the sheath heater 2 is maintained at the first target temperature (TG = 900 ° C. in this embodiment) after starting.

  Thereafter, if it is determined in step SF1 (see FIG. 11) that the processing after the start-up glow step has passed a predetermined post-start-up glow time (for example, 3 minutes) (YES), after low temperature start in step SF3 The glow energization is turned off (time t = t5), and the after-start glow flag is cleared. Then, in the subroutine of step SA (see FIG. 13), NO is determined in any of steps SA1, SA2, and SA3, and transition glow energization is turned off (maintains off) in step SA5. Thereby, the energization to the sheathed heater 2 is terminated without passing through the low temperature start-up glow step (processing by step SF).

  In step SE1 (see FIG. 10), it is determined in step SE1 (see FIG. 10) that the process by the glow step after the high temperature start has passed a predetermined high temperature maintenance time (for example, 3 minutes) without determining NO (σa ≦ σth) in step SD. If YES (YES), the glow energization after high temperature start is turned off in step SE3, and the post-start glow flag is cleared. Then, in the subroutine of step SA (see FIG. 13), NO is determined in any of steps SA1, SA2, and SA3, and transition glow energization is turned off (maintains off) in step SA5. Thereby, the energization to the sheathed heater 2 is terminated without passing through the low temperature start-up glow step (processing by step SF).

The engine often does not stabilize its rotation immediately after starting (see FIG. 14B). It is thought that misfire occurs in some cylinders.
In particular, misfiring is likely to occur in a low temperature environment, the unstable state of the rotation speed N (rough idle state) continues for a long time, and unpleasant vibration and noise and unburned gas are likely to be discharged.
Specifically, for example, as in the comparative example indicated by a broken line in FIG. 14A, after the cranking slow step is completed (after time t3), the low temperature start glow step is not performed without passing through the high temperature start glow step. The temperature TG of the sheathed heater 2 is set to the first target temperature (for example, TG = 900 ° C.) after starting. Then, as shown by a broken line in FIG. 14B, the rough idle state continues for a long time and does not easily fall within the idling speed Ni. Since the temperature TG of the sheathed heater 2 is relatively lowered, misfire is likely to occur, the temperature of the engine (engine block) itself does not rise, and the rough idle state is considered to have continued.
This can also be seen from the fact that the moving standard deviation σa of the engine speed N calculated in step S7, indicated by a broken line in FIG. Conversely, it can also be seen that the moving standard deviation σa is appropriate as an index for evaluating the rotational stability of the engine.

On the other hand, in the present embodiment including the glow step after the high temperature start, the temperature TG of the heater 2 is kept high as indicated by the solid line in FIG. 14A even after the engine is started (after time t3). (In this example, TG = 1000 ° C.). For this reason, as shown in FIG. 14B, the engine speed N is unstable immediately after the start (after time t3), but the engine speed N is stabilized earlier than in the comparative example (broken line). It has become.
This is because the temperature TG of the heater 2 was kept at a relatively high temperature (TG = 1000 ° C.), so that the ignition assistance in each cylinder was reliably performed and misfire could be suppressed, so that the rotational speed N was stabilized early. .

As described above, the glow plug energization control device 101 according to the present embodiment includes the pre-glow means, the transition glow means, the cranking glow means, and the start-up consisting of the glow means after the high temperature start and the glow means after the low temperature start. A rear glow means.
Among these, the pre-glow means controls energization to the glow plug GP so as to rapidly raise the temperature TG of the sheathed heater 2 when the key switch KSW is set to the on position. Specifically, continuous energization is performed.

  On the other hand, the transition glow means, following the energization control by the pre-glow means, the duty ratio of the voltage waveform applied to the glow plug GP based on the voltage value V1 and the like applied from the battery BT to the glow plug GP and the current value I1 and the like. Dh is calculated, and the energization to the glow plug GP is PWM controlled by the duty ratio Dh. By this means, after the energization control by the pre-glow means, the energization to the glow plug GP is controlled in anticipation of a decrease in the temperature TG due to the heat drawn from the sheathed heater 2 to the surroundings. Moreover, the PWM control has an advantage that the input power to the glow plug GP can be easily adjusted by the duty ratio Dh. Accordingly, it is possible to prevent the temperature TG of the sheathed heater 2 from dropping and improve the engine startability.

  The cranking glow means is based on the voltage value V1 applied from the battery BT to the low plug GP during the period when the key switch KSW is at the start position and the engine is cranked during the energization control by the transition glow means. Thus, the duty ratio Dk of the voltage waveform applied to the glow plug GP is calculated. Further, this means is a duty ratio calculated by the transition glow means when it is assumed that the voltage value of the battery BT in the control period by the transition glow means is the same as the voltage value of the battery BT in the control period by this means. The energization to the glow plug GP is PWM-controlled with a larger duty ratio Dk. As a result, the energization of the glow plug GP can be controlled in anticipation of the voltage decrease of the battery BT that occurs during the cranking period and the temperature decrease due to cooling of the sheathed heater 2 due to fuel injection or the like. Moreover, the PWM control has an advantage that the input power to the glow plug GP can be easily adjusted by the duty ratio Dk. Therefore, even during the cranking period, it is possible to prevent the temperature TG of the sheathed heater 2 from dropping and improve the engine startability.

Among the after-start glow means, the after-start low-temperature glow means is the case where the after-high temperature start glow means described below is not executed after the engine is started, and the moving standard deviation σa of the rotational speed N is equal to or less than the threshold value σth. It is executed when the rotational speed N has become stable. This low temperature start-up glow means supplies electric power smaller than the electric power supplied to the glow plug GP by the pre-glow means to the glow plug GP, so that the sheathed heater 2 is set to a first target temperature after a relatively low start to achieve stable heating. As a result, the temperature TG of the sheathed heater 2 is maintained at a certain level even after the engine is started, so that warming up of the combustion chamber of the engine is promoted, and misfires and diesel knocks are prevented. Generation of smoke, emission of HC components, etc. can be suppressed.
On the other hand, among the post-start glow means, the high temperature post-start glow means has a period during which the moving standard deviation σa of the engine speed N is not calculated after the engine starts, and the moving standard deviation σa is greater than a predetermined threshold σth. Is also executed, that is, when the rotational speed is not stable. This high temperature start-up glow means supplies electric power to the glow plug GP and maintains the sheathed heater 2 at a relatively high second target temperature (for example, TG = 1000 ° C.) after start-up. This especially promotes warm air in the combustion chamber of the engine, suppresses the occurrence of misfire and diesel knock, and suppresses noise and noise, unburned gas emissions, white smoke generation, HC component emissions, etc. The engine speed can be stabilized at an early stage.

In the above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the glow plug energization control system 100 shown in the embodiment, the driver (operator) operates the key switch KSW to the on position or the start position. However, in response to an instruction (button instruction or the like) from the driver (operator), the driver starts the plug low step in the same manner as when the key switch is turned on, and at an appropriate time after the transition to the transition glow step, The present invention can also be applied to an automatic start method such as a button start method that shifts to a cranking glow step, as in the case where the driver sets the key switch to the start position.

In the embodiment, the moving standard deviation σa of the engine speed N is used to evaluate the engine rotational stability, but a difference value of the engine speed N can also be used. For example, there is a method of determining that a predetermined rotational stability is obtained when the difference value is continuously smaller than a certain threshold value.
In the above-described embodiment, since the moving standard deviation σa cannot be obtained for a while after the engine is started, NO is determined in step SC and the glow means after the high temperature start in step SE is always executed. . However, after the engine is started, the glow means after the high-temperature start is executed after it is determined that the rotation stability is low by an index for evaluating the rotational stability of the engine (moving standard deviation σa or difference value of the rotational speed N). You may make it do.

Further, in the above-described embodiment, in the transition glow step (time t1 to t2), the cranking glow step (time t2 to t3), and the glow step after high temperature start (time t3 to t4), the temperature TG of the heater 2 is any Although it was made to become the same 1000 degreeC, it cannot be overemphasized that these may not be the same. Accordingly, for example, the temperature TG of the heater 2 in the glow step after high temperature start (time t3 to t4) can be made higher than the cranking glow step (time t2 to t3).
On the other hand, in the glow step after the low temperature start (time t4 to t5), the example in which the temperature TG of the heater 2 is maintained at 900 ° C. lower than the glow step after the high temperature start (time t3 to t4) is shown. However, the value of the second target temperature after starting the heater 2 in the glow step after the high temperature start (time t3 to t4) in consideration of the durability of the heater 2 (glow plug GP), the effect of ignition assistance, etc. An appropriate value among the smaller values may be selected as the first target temperature after starting.

It is a circuit diagram showing a glow plug energization control system including a glow plug energization control device according to an embodiment. It is a fragmentary sectional view of the glow plug used in an embodiment. It is explanatory drawing which shows the state which attached the glow plug to the engine. It is a flowchart which shows the main routine flow of the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart which shows the subroutine of a start signal input process among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart which shows the duty ratio Da1 calculation subroutine in the glow after a cold start among the energization control by the glow plug energization control apparatus which concerns on embodiment. It is a flowchart which shows the duty ratio Da2 calculation subroutine in the glow after a high temperature start among the energization control by the glow plug energization control apparatus which concerns on embodiment. It is a flowchart which shows the movement standard deviation calculation subroutine of rotation speed among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart which shows a cranking glow process subroutine among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart which shows the glow process subroutine after high temperature start among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart which shows the glow process subroutine after a low temperature start among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart which shows the pre-glow process subroutine among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. It is a flowchart shown about the transition glow process subroutine among the electricity supply control by the glow plug electricity supply control apparatus which concerns on embodiment. (A) is a graph showing the time variation of the moving standard deviation σa of the engine speed N, and (c) is the engine speed N of the sheathed heater temperature TG. .

Explanation of symbols

GP, GP1, GPn Glow plug 2 Seed heater (resistance heater)
3 metal shell 11 sheath tube 21 heating coil 23 control coil 100 glow plug energization control system 101 glow plug energization control device 104, 106 interface circuit 1051, 105n switching element 111 main control unit 201 ECU
211 Alternator KSW Key switch BT Battery V1, Vn Voltage value I1, In (applied to the glow plug) Current value N (flowed through the glow plug) N (Engine) speed (speed information)
Nth threshold value Ni idling speed σa standard deviation of engine speed TG temperature of sheathed heater

Claims (5)

A glow plug energization control device that controls energization from a battery to a resistance heating heater of a glow plug installed in the engine during a period before and after starting the engine,
After starting the cranking of the engine, on the basis of start information indicating that the engine has started, having a post-start glow means for energizing the glow plug;
The after-start glow means is
A stability evaluation means for evaluating the rotational stability of the engine;
A low temperature start glow means for controlling energization of the resistance heater in a predetermined first start control pattern when it is evaluated that rotational stability of a predetermined level or more is obtained;
When it is evaluated that the predetermined level of rotational stability has not been obtained, the resistance heating heater is heated at a higher temperature than when the resistance heating heater is energized and controlled by the glow means after the low temperature starting. Including a high-temperature start-up glow means for controlling energization with a post-control pattern ,
The stability evaluation means is
A rotation speed stability evaluation means for evaluating the rotation stability of the engine using the rotation speed information regarding the rotation speed of the engine at each time point acquired by communication from the outside,
The rotational speed stability evaluation means is:
A moving standard deviation calculating means for calculating a moving standard deviation of the rotational speed using the rotational speed information,
A glow plug energization control device comprising: a determination unit configured to determine that the predetermined level of rotational stability is not obtained when the movement standard deviation is greater than a predetermined value . The glow plug energization control device according to claim 1 ,
The glow plug energization control device that controls energization of the resistance heating heater so that the temperature of the resistance heating heater becomes a first target temperature and maintains the temperature after the cold start glow means. A glow plug energization control device according to claim 2 ,
The low temperature start glow means calculates a duty ratio Da1 of a voltage waveform applied to the glow plug based on the resistance value of the resistance heating heater, and PWM is used to energize the resistance heating heater based on the duty ratio Da1. Glow plug energization control device to control. A glow plug energization control device according to claim 2 or claim 3 , wherein
The glow means after the high-temperature start-up is a glow plug energization that controls energization of the resistance heater so that the temperature of the resistance heater becomes a second target temperature higher than the first target temperature. Control device. A glow plug energization control device according to claim 4 ,
The glow means after high temperature start calculates a duty ratio Da2 of a voltage waveform applied to the glow plug based on the resistance value of the resistance heating heater, and the duty ratio Da2 applies PWM to the resistance heating heater. Glow plug energization control device to control.