JP5091919B2 - Glow plug energization control device - Google Patents

Description

  The present invention relates to an energization control device for controlling power supplied from a power supply device to a glow plug.

  A glow plug having a heating heater is generally used for preheating or improving combustion of a diesel engine.

  Conventionally, as a control device for controlling the heat generation of the glow plug, an energization signal output means for outputting a signal for determining whether the glow plug can be energized from a power supply (battery), and when the signal is input to the gate A device including an FET that forms an energization path from a battery to a glow plug is known. The operation of the control device will be described in detail. When the key switch is turned on, the energization signal output is performed so that the temperature of the heater is increased toward the first target temperature sufficient to start the engine. When the means outputs a signal permitting energization, the FET forms the energization path, and power is supplied from the battery to the glow plug. Then, after the temperature of the heater of the glow plug reaches the first target temperature, the glow plug is supplied to the glow plug so that the temperature of the heater is maintained at the second target temperature for a predetermined time (for example, 180 seconds). Control energization. More specifically, the energization signal output means outputs a rectangular wave signal (PWM signal) in which the width (time) of the signal allowing energization in one cycle, that is, the duty ratio is changed, so that an energization path is formed by the FET. Increase or decrease the time (ON time) As a result, the amount of power supplied to the glow plug is controlled (PWM control), and consequently, the temperature of the heater is controlled so as to become the second target temperature.

By the way, when the duty ratio is V _{T which} is a voltage (target voltage) necessary for raising the glow plug to the target temperature or maintaining it, the output voltage of the power supply device is V. Generally, it is obtained from (V _T / V) ² (see, for example, Patent Document 1).

JP 2004-232503 A

However, in view of the waveform (energization waveform) of the voltage applied to the glow plug, the PWM signal and the delay in switching the ON state where the FET energization path is formed and the OFF state where the path is disconnected are Compared to this, there is a delay in the start timing and end timing of the waveform, and more time is required for rising and falling (that is, the rising and falling slopes are more gradual). There are things to do. For this reason, an energized waveform is rectangular and an ideal case where no delay such as a rise occurs is assumed (V _T / V) ^2. Depending on the duty ratio determined by ² , the heating heater (glow plug) is used. On the other hand, the actually supplied effective voltage may be shifted from the target voltage. As a result, there is a concern that proper temperature control of the glow plug becomes difficult. In addition, there is a concern that the intended combustion improvement effect cannot be obtained due to the influence.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately control the temperature of the glow plug by complementing the difference between the effective voltage supplied to the glow plug and the target voltage. An object of the present invention is to provide an energization control device that can be used.

  Hereinafter, each configuration suitable for solving the above-described object will be described in terms of items. In addition, the effect specific to the corresponding structure is added as needed.

Configuration 1. The energization control device for the glow plug of this configuration includes energization signal output means for outputting a PWM signal for determining whether or not energization to the glow plug is possible from the power supply device,
Switching means for switching energization / non-energization to the glow plug based on the PWM signal;
A glow plug energization control device that PWM-controls the power supplied from the power supply device to the glow plug using a duty ratio,
The output voltage of the power supply device and is V, when the target voltage to be supplied to the glow plug was V _T,
The duty ratio is a predetermined correction value α,
(V _T / V) ² + α
Determined by
The predetermined correction value α is
An integral value of the square of the voltage of the energization waveform in a time Tondelay from the start of the rise of the PWM signal to the start of the energization waveform indicating the voltage supplied to the glow plug;
An integral value of the square of the voltage V ₂ of the energization waveform at a time TonSR from the start of the energization waveform to the completion of the rise;
An integral value of the square of the voltage V ₃ of the energization waveform in the time from the completion of the rise of the energization waveform to the start of the fall of the PWM signal;
An integral value of the square of the voltage V ₄ of the energization waveform at a time Toffdelay from the fall start of the PWM signal to the fall start of the energization waveform;
An integral value of the square of the voltage V ₅ of the energized waveform at a time ToffSR from the start of falling of the energized waveform to the completion of falling;
The value is determined based on the calculated effective voltage obtained by dividing the value obtained by dividing by the period of the PWM signal and then by the 1/2 power.

  According to the above configuration 1, the calculated effective voltage is different from the effective voltage assuming a rectangular energization waveform in the related art, and the delay of the rise start time and fall end time of the energization waveform and the time required for the rise and fall are determined. Derived taking into account. Therefore, the correction value α is determined based on the calculated effective voltage (for example, based on the difference between the calculated effective voltage and the effective voltage assuming a conventional rectangular energization waveform), and the correction value α is added. By using the duty ratio, the deviation of the effective voltage with respect to the target voltage due to the delay of the rising start timing and the falling end timing can be compensated. As a result, the temperature of the glow plug can be accurately controlled according to the actual situation.

  By the way, in recent years, the glow plug energization control device is required to have high functionality and high performance. Specifically, it is equipped with a highly functional OBD (On Board Diagnosis) function or performs separate energization control for each glow plug provided in a plurality of cylinders. In order to respond to these, it is conceivable to shift the installed microcomputer to a high-performance microcomputer or increase the processing capacity of the power supply control device by increasing the number of components. However, a high-performance microcomputer is obtained and expensive, and increasing the number of parts has a negative aspect such as increasing the size of the apparatus and increasing the cause of failure.

  From such a situation, an effective energization control method is required while simplifying the processing. Therefore, the energization control device for the glow plug of this configuration includes the following configurations as the second and third configurations.

  Configuration 2. In the glow plug energization control device of this configuration, in the configuration 1, the correction value α is determined based on the calculated effective voltage obtained by setting the time TonSR and the time ToffSR to be equal to each other. To do.

  As described above, the temperature of the glow plug can be accurately controlled by the configuration 1 of the present invention. In simplifying the processing, it is desirable that the accuracy hardly decreases with respect to the reduction in the number of processing steps by the simplification. In calculating the correction value α from this point of view, according to the configuration 2, the effective voltage is calculated on the basis that the time TonSR required for the energization waveform to rise is equal to the time ToffSR required for the fall. A correction value α is determined. Therefore, it is possible to simplify the expression representing the calculated effective voltage, and further simplify the expression for determining the correction value α. As a result, in energization control of the glow plug, which requires control in units of several μs, it is possible to more reliably prevent a situation such as processing delay and to stably control the temperature of the glow plug. The configuration that further promotes this viewpoint is the configuration 3 described below.

Configuration 3. The energization control device for the glow plug of this configuration includes energization signal output means for outputting a PWM signal for determining whether or not energization to the glow plug is possible from the power supply device,
Switching means for switching energization / non-energization to the glow plug based on the PWM signal;
A glow plug energization control device that PWM-controls the power supplied from the power supply device to the glow plug using a duty ratio,
The output voltage of the power supply device is V, the target voltage to be supplied to the glow plug is V _T , the period of the PWM signal is T, and
The time Tondelay from the start of rising of the PWM signal to the start of rising of the energization waveform indicating the voltage supplied to the glow plug, the time TonSR from the start of rising of the energization waveform to the completion of rising, and the start of falling of the PWM signal When the time Toffdelay until the falling start of the energized waveform and the time ToffSR from the start of falling of the energized waveform to the completion of falling are set to the same time TS,
The duty ratio is determined according to an equation of (V _T / V) ² + (TS / 3T).

  As described above, it is assumed that the time required for rising and the time required for falling are substantially equal. Similarly, the time (delay time) Tondelay from the start of the rise of the PWM signal to the start of the rise of the energization signal, and the time (delay time) Toffdelay from the start of the fall of the PWM signal to the start of the fall of the energization signal As for, both are almost equal. These times Tondelay, TonSR, Toffdelay, ToffSR are usually several μs to several tens μs. For this reason, even if the correction value α is determined by setting these as equal times, there is almost no difference in the correction value α as compared with the case where the value of each time is individually set.

  Therefore, according to the configuration 3, “TS / 3T” that can be derived when the time Tondelay, the time TonSR, the time Toffdelay, and the time ToffSR are set to the same time TS is set as the correction value α, and the duty ratio Is corrected. Therefore, the control process can be further simplified, and the heat generation of the glow plug can be controlled more stably.

  Note that “TS / 3T” as the correction value α is a time TS in which the time Tondelay, the time TonSR, the time Toffdelay, and the time ToffSR are equal to each other, and the rising part and the falling part of the energization waveform are time. Can be derived by assuming that it is a linear function.

  Also, any one of the times Tondelay, TonSR, Toffdelay, and ToffSR may be exceptionally several hundred μs. However, in light of this exception, the combustion improvement effect obtained when the processing man-hours are increased and the accuracy of energization control is improved, and these are made equal to each other to simplify the processing. For example, a plurality of cylinders (glow plugs) When compared with the effect of improving combustion when separate energization control is performed, the latter is more preferable. Based on such a background, the technical value of Configuration 3 is found.

  Configuration 4. The glow plug energization control device according to the present configuration is configured so that, in any one of the configurations 1 to 3, the duty ratio is used to maintain the glow plug temperature at a predetermined target temperature after the internal combustion engine is started. It is characterized by controlling energization to the glow plug.

  As described above, the time required for rising and falling affects the effective voltage, but the influence is particularly large when maintaining the temperature of the glow plug as compared to when the temperature of the glow plug is rapidly increased. It will be a thing. This is because when the temperature of the glow plug is maintained, the voltage applied to the glow plug is relatively small, in other words, the duty ratio is small, so that the rising portion and the falling portion occupy the energization waveform. This is because the ratio becomes relatively large.

  In this regard, according to the configuration 4, when the temperature of the glow plug is maintained at a predetermined target temperature after the internal combustion engine is started, the glow plug is energized using the duty ratio to which the correction value α is added. Be controlled. Therefore, in the case where the deviation of the effective voltage with respect to the target voltage tends to be relatively large, the influence due to the deviation can be effectively reduced.

Note that “when the temperature of the glow plug is maintained at a predetermined target temperature” can be exemplified when the value of (V _T / V) ² is 65% or less. The above configuration 1 and the like are more effective as the value of (V _T / V) ² is smaller. Therefore, it is more significant to use the duty ratio when (V _T / V) ² is 60% or less, and when (V _T / V) ² is 50% or less, the duty ratio is It is even more significant to use.

(A) is the partially broken front view of the glow plug of this embodiment, (b) is the elements on larger scale of the glow plug front-end | tip part. It is a block diagram for showing the composition of an energization control device. (A) is a reference diagram showing the shape of an ideal energization waveform when the duty ratio is T1 / T, and (b) is an energization waveform from the FET when the duty ratio is T1 / T. It is a reference figure which shows a shape. It is a graph which shows the relationship between a voltage deviation rate and an output voltage.

  Hereinafter, an embodiment will be described with reference to the drawings. First, the structure of the glow plug 1 that is energized and controlled by the glow plug energization control device 30 of the present invention will be described. Fig.1 (a) is a partially broken front view which shows an example of the glow plug which comprises a sheath heater, FIG.1 (b) is sectional drawing of a glow plug front-end | tip part.

  As shown in FIGS. 1A and 1B, the glow plug 1 includes a cylindrical metal shell 2 and a sheath heater 3 attached to the metal shell 2.

  The metal shell 2 has a shaft hole 4 penetrating in the direction of the axis CL1, and the outer peripheral surface thereof has a hexagonal cross section for engaging a screw portion 5 for attachment to a diesel engine and a tool such as a torque wrench. The tool engaging portion 6 is formed.

  The sheath heater 3 is configured by integrating a tube 7 and a middle shaft 8 in the direction of the axis CL1.

  The tube 7 is a cylindrical tube whose front end portion is mainly composed of iron (Fe) or nickel (Ni), and the rear end of the tube 7 is sealed with an annular rubber 17 between the center shaft 8. ing.

  In addition, inside the tube 7, a heating coil 9 joined to the tip of the tube 7 and a control coil 10 connected in series to the rear end of the heating coil 9 are insulated powder such as magnesium oxide (MgO) powder. 11 is enclosed. However, although the heat generating coil 9 is electrically connected to the tube 7 at its tip, the outer peripheral surface of the heat generating coil 9 and the control coil 10 and the inner peripheral surface of the tube 7 are insulated from each other by the intervening insulating powder 11. It has become.

  The heating coil 9 is constituted by a resistance heating wire made of, for example, an Fe-chromium (Cr) -aluminum (Al) alloy. On the other hand, the control coil 10 is a resistor whose main component is a material having a temperature coefficient of electrical resistivity greater than that of the material of the heat generating coil 9, for example, Co or Ni represented by a cobalt (Co) -Ni-Fe alloy. It is composed of heating lines. Thereby, the control coil 10 increases the electric resistance value by receiving its own heat generation and heat generation from the heat generation coil 9, and controls the power supply amount to the heat generation coil 9. Therefore, relatively large electric power is supplied to the heating coil 9 in the initial stage of energization, and the temperature of the heating coil 9 rises rapidly. Then, the control coil 10 is heated by the heat generation, the electric resistance value increases, and the power supply to the heat generating coil 9 decreases. As a result, the temperature rise characteristic of the sheath heater 3 becomes a form in which the temperature is saturated after the temperature is rapidly raised in the initial stage of energization, and thereafter the power supply is suppressed by the action of the control coil 10. That is, the presence of the control coil 10 makes it possible to prevent the temperature of the heat generating coil 9 from excessively rising (overshoot) while improving the rapid temperature rise.

  In addition, the tube 7 is formed with a small-diameter portion 7a that accommodates the heating coil 9 and the like at the distal end thereof by swaging or the like, and a large-diameter portion 7b having a larger diameter than the small-diameter portion 7a on the rear end side Is formed. The large diameter portion 7 b is press-fitted and joined to the small diameter portion 4 a formed in the shaft hole 4 of the metal shell 2, so that the tube 7 is held in a state of protruding from the tip of the metal shell 2.

  The middle shaft 8 is inserted at its tip into the tube 7, is electrically connected to the rear end of the control coil 10, and is inserted through the shaft hole 4 of the metal shell 2. The rear end of the middle shaft 8 protrudes from the rear end of the metal shell 2. At the rear end of the metal shell 2, the rubber-made O-ring 12, the resin-made insulating bush 13, and the insulating bush 13 are removed. A pressing ring 14 for preventing and a nut 15 for connecting a current-carrying cable are fitted into the middle shaft 8 in this order from the tip side.

  Next, the energization control device 30 for the glow plug, which is a feature of the present invention, will be described.

  As shown in FIG. 2, the energization control device 30 includes an energization signal output unit 31, a switching unit 32, and an ECU 34 having a CPU.

  The ECU 34 is a so-called microcomputer, and in the present embodiment, one made by Renesas (R8C tiny series, 8 bits, 48 pins) is used. The processing capacity of the microcomputer is not necessarily proportional to the number of bits or the number of pins, but in addition to the above, the processing capacity is not so high, but an inexpensive microcomputer (for example, 740 series, 8 bits, 32 pins) is used. Also good. The present invention is relatively effective in an energization control apparatus using such a microcomputer, and an energization control apparatus with a small resource margin such as performing energization control separately for each of a plurality of cylinders (glow plugs).

  For the switching means 32, an FET 321 which is a semiconductor switch is used. An FET driver 322 for driving the FET 321 is also used. Specifically, the source of the FET 321 is connected to a power supply device (battery) 35 having a predetermined output voltage (for example, 12 V), and the drain is connected to the glow plug 1. The FET 321 is connected to the ECU 34 so that the PWM signal from the energization signal output means 31 is input to the gate of the FET 321 via the FET driver 322 configured by a transistor and a plurality of predetermined resistors (both not shown). The Further, the FET 321 is a P-channel one.

  The energization signal output means 31 is controlled by the ECU 34 and outputs a rectangular PWM signal indicating the timing of energizing the glow plug 1 from a power supply (battery) 35 having a predetermined output voltage (for example, 12 V). And output to the switching means 32. The operation of the energization signal output unit 31 will be described in detail. The energization signal output unit 31 outputs a High signal as a PWM signal to the switching unit 32 when energizing the glow plug 1 from the power supply device 35. Then, a predetermined drive voltage is applied to the FET 321, an energization path between the source and the drain is formed, and energization to the glow plug 1 is started. On the other hand, when the energization from the power supply device 35 to the glow plug 1 is stopped, that is, deenergized, the energization signal output means 31 outputs a Low signal as a PWM signal to the switching means 32. Then, no drive voltage is applied to the FET 321, the energization path between the source and drain is closed, and the energization to the glow plug 1 is stopped. Thus, the output signal of the energization signal output means 31 and the state of the switching means 32 (either energization or non-energization) have a one-to-one correspondence, and the state of the switching means 32 from the energization signal output means 31 is uniquely defined. It is possible to judge automatically. In the temperature control of the sheath heater 3, so-called PWM (Pulse-Width-Modulation) control is performed in which the energization amount to the glow plug 1 is controlled by changing the width of the High signal in one cycle. It has become. Further, the duty ratio in PWM control (the length of the High signal in one cycle of the PWM signal) is set by the ECU 34 based on a method described in detail later.

  Incidentally, it takes some time to form and close the energization path of the FET 321 and the energization path of the transistor of the FET driver 322. Therefore, even if a rectangular PWM signal is output, the energization waveform indicating the voltage output from the FET 321 to the glow plug 1 has a trapezoidal shape. In addition, the start timing of the energization waveform rises or falls with a slight delay compared to the start timing of the rise or fall of the PWM signal.

Therefore, in the present embodiment, the ECU 34 is set in advance as the time required for the rise and fall of the energization waveform and the delay time from the rise (fall) of the PWM signal to the rise (fall) of the energization waveform. time and TS, and supplies the required voltage to the glow plug 1 (target voltage) and V _T, the output voltage of the power supply device 35 is V, when one cycle of the PWM signal is T, the following (1) Based on the equation, the duty ratio D is calculated. Then, the ECU 34 performs PWM control based on the calculated duty ratio D. In the present embodiment, the time TS is set based on the performance of the transistors included in the FET 321 and the FET driver 322.

D = (V _T / V) ² + (TS / 3T) (1)
For V, a voltage output from the FET 321 to the glow plug 1 may be used instead of the output voltage of the power supply device 35.

Here, the equation (1) is an equation calculated based on the following idea. When T1 is a time when the PWM signal becomes High, the duty ratio is T1 / T. When PWM control is performed by this, ideally a rectangular energization waveform as shown in FIG. Simultaneously with the output of the PWM signal, it is output from the FET 321 to the glow plug 1, and the effective voltage becomes V · (T1 / T) ^1/2 . However, actually, as described above, there is a delay in the rise of the energization waveform. Accordingly, the energization waveform from the FET 321 to the glow plug 1 rises with a delay of time Tondelay from the time when the PWM signal is output, as shown in FIG. While the PWM signal rises instantaneously, time TonSR is required from the start of the rise of the energization waveform to the completion of the rise. Further, there is a delay of time Toffdelay from the start of falling of the PWM signal to the start of falling of the energized waveform, and time ToffSR is required from the start of falling of the energized waveform to the completion of falling.

Here, in general, the effective voltage of the energization waveform is obtained as follows. In other words, a value (calculated effective voltage) S obtained by integrating the square of the voltage of the energization waveform in one period with time is divided by the period T of the PWM signal, and the divided value is obtained by multiplying by 1/2. It is done. According to this calculation method, first, the calculated effective voltage S of the energization waveform is set to _VL when the energization waveform is Low, von is an expression indicating the voltage at the rising of the energization waveform, and when the energization waveform is High. the voltage and V _H, the equation indicating the voltage at the time of the fall and _{voff, V 1 = V 6 =} V L in the present _{invention, V 2 = von, V 3} = V 4 = V H, V 5 = voff And can be expressed by the following equation (2). (V ₆ represents the voltage of the energization waveform in the time from the completion of the fall of the energization waveform to the start of the rise of the next energization waveform. The voltage V _H and the output voltage V of the power supply device are substantially equal. )

In the present embodiment, the voltage value V _L when the energization waveform is Low is 0 (V). Further, the expression von can be approximated to a linear expression of time t shown by the expression (3), and the voff can be approximated to an expression (4).

Therefore, by substituting V _L = 0, the above expressions (3), and (4) into the above expression (2), S is expressed by the following expression (5).

  And the effective voltage Veff is represented by following Formula (6) by using the said Formula (5).

Therefore, when the duty ratio is T1 / T [= (V _T / V) ² ], the effective voltage is as follows compared with the effective voltage V · (T1 / T) ^1/2 of the ideal waveform. It turns out that it falls only by Tcomp represented by Formula (7).

Therefore, in order to make the effective voltage equal to the target voltage, it is conceivable to calculate the duty ratio based on (T1 + Tcomp) / T obtained by adding Tcomp to T1. Here, since T1 / T = (V _T / V) ² , the equation for calculating this duty ratio is expressed by (V _T / V) ² + Tcomp / T, and Tcomp / T is obtained. Further, assuming that the time Tondelay, the time TonSR, the time Toffdelay, and the time ToffSR are equal to each other (the value is “TS”), Tcomp = TS / 3, and the above equation (1) is obtained. Can do.

  As described above in detail, according to the present embodiment, unlike the conventional effective voltage assuming a rectangular energization waveform, it is required for the delay of the rise start time and fall end time of the energization waveform, and for the rise and fall. The duty ratio D is corrected based on the calculated effective voltage taking time into account. For this reason, it is possible to compensate for the delay in the rise start time and the fall end time, and the deviation of the effective voltage with respect to the target voltage due to the time required for the rise and fall, and the temperature of the glow plug 1 is accurately adjusted according to the actual situation. It can be controlled well.

  Further, since the relatively simplified expression “TS / 3T” is used as the correction value α, the duty ratio can be calculated more easily. Therefore, in energization control of the glow plug 1 that requires control in units of several μs, it is possible to more reliably prevent a situation such as processing delay and to control the temperature of the glow plug 1 more stably. it can.

  Further, as described above, since the equation for calculating the duty ratio is simple, the processing capability required for the ECU 34 may be relatively low. For this reason, the ECU 34 having a relatively low processing capability can be used, and an increase in manufacturing cost of the energization control device 30 can be prevented.

Next, when the equation for determining the duty ratio is set to (V _T / V) ² (corresponding to the prior art), the equation for determining the duty ratio is (V _T / V) ² + ( when set to TS / 3T) de (corresponding to the invention), while variously changing the output voltage V of the power supply, with respect to the target voltage V _T, the ratio of the difference between the target voltage V _T and the effective voltage (the voltage The deviation rate was measured. FIG. 4 shows the relationship between the output voltage V of the power supply device and the voltage deviation rate. In the figure, graph 1 represents the result when the equation for determining the duty ratio is set to (V _T / V) ² , and graph 2 represents the equation for determining the duty ratio ( The result is shown when V _T / V) ² + (TS / 3T) is set. The target voltage was 4.3 Vrms.

As shown in FIG. 4, when the equation for determining the duty ratio is (V _T / V) ² , it has been found that the voltage deviation rate increases as the output voltage of the power supply device increases. . This is because when the output voltage increases, the ratio of the rising and falling parts in the energization waveform becomes relatively large, so the adverse effect of a decrease in effective voltage due to rising and falling delays is noticeable. It is thought that this is because it has been.

On the other hand, when the equation for determining the duty ratio is set to (V _T / V) ² + (TS / 3T), the voltage deviation rate does not increase even if the output voltage increases. It became clear that the effective voltage can be made substantially equal to the target voltage. This is because the ratio of the rising portion and the like in the energization waveform becomes relatively large as the output voltage increases, but the rise or fall delay is caused by adding (TS / 3T) as the correction value α. This is thought to be due to the suppression of adverse effects due to the above.

As described above, by setting the equation for determining the duty ratio to (V _T / V) ² + (TS / 3T), it is possible to more reliably prevent the effective voltage from deviating from the target voltage, It can be said that the heat generation control of the glow plug can be performed more accurately.

  In addition, it is not limited to the description content of the said embodiment, For example, you may implement as follows. Of course, other application examples and modification examples not illustrated below are also possible.

(A) In the above embodiment, the duty ratio is (V _T / V) ² + (TS / 3T), but this duty ratio uses the von and voff as a first-order approximation, and the time Tondelay , Time TonSR, time Toffdelay, and time ToffSR are derived with the same time TS. Therefore, in the above-described duty ratio derivation process, the von and voff equations may be changed to other equations, or the time Tondelay and the time TonSR may be set to different values.

(B) Although the value of TS in the above embodiment is constant regardless of the magnitude of the target voltage V _T , the value of TS may be changed as appropriate according to the target voltage V _T. Good. Therefore, for example, when the target voltage V _T [value of (V _T / V) ² ] is relatively large and the influence of rising or falling delay is relatively small, TS is set to a small value, If the target voltage V _T [value of (V _T / V) ² ] is relatively small and the influence of the rise or fall delay is relatively large, TS may be set to a large value.

(C) In the above embodiment, (V _T / V) regardless of the value of ^2, although the fact that the correction of the duty ratio by the correction value alpha, a relatively large value of (V _T / V) ² ( For example, in the case of exceeding 0.6), the duty ratio may be determined based on the formula of (V _T / V) ² without using the correction value α (that is, TS = 0). .

  (D) In the above embodiment, the energization control device 30 is configured to control the energization of the glow plug 1 (metal glow plug) having the heat generating coil 9, but the control target by the energization control device 30 is It is not limited to this. For example, the dimension of each member, the composition of the coil, and the like can be appropriately changed to those that can be easily controlled by the energization control device 30. Further, the glow plug is not limited to the metal glow plug. Accordingly, the energization control device 30 may be configured to control energization of the ceramic glow plug having the ceramic heater.

  (E) In the above embodiment, the energization control device 30 has been described as being intended for one cylinder (single cylinder engine) that controls energization to one glow plug 1. This is to briefly explain the gist of the present invention, and the control target of the energization control device 30 is not limited to this. Rather, the energization control device 30 of the present invention is significant when controlling energization to a plurality of glow plugs mounted on a multi-cylinder engine. That is, the energization control for each glow plug may be different (for example, the rise and fall timings of the PWM signal are different for each glow plug). In such a case, the resources of the microcomputer are insufficient. It tends to be. At this time, particularly in the second and third configurations of the present invention, sufficient resources of the microcomputer can be secured, and a plurality of glow plugs can be controlled separately.

  DESCRIPTION OF SYMBOLS 1 ... Glow plug, 30 ... Energization control apparatus, 31 ... Energization signal output means, 32 ... Switching means, 35 ... Power supply device.

Claims (4)

Energization signal output means for outputting a PWM signal for determining whether or not the glow plug can be energized from the power supply device;
Switching means for switching energization / non-energization to the glow plug based on the PWM signal;
A glow plug energization control device that PWM-controls the power supplied from the power supply device to the glow plug using a duty ratio,
The output voltage of the power supply device and is V, when the target voltage to be supplied to the glow plug was V _T,
The duty ratio is a predetermined correction value α,
(V _T / V) ² + α
Determined by
The predetermined correction value α is
An integral value of the square of the voltage of the energization waveform in a time Tondelay from the start of the rise of the PWM signal to the start of the energization waveform indicating the voltage supplied to the glow plug;
An integral value of the square of the voltage V ₂ of the energization waveform at a time TonSR from the start of the energization waveform to the completion of the rise;
An integral value of the square of the voltage V ₃ of the energization waveform in the time from the completion of the rise of the energization waveform to the start of the fall of the PWM signal;
An integral value of the square of the voltage V ₄ of the energization waveform at a time Toffdelay from the fall start of the PWM signal to the fall start of the energization waveform;
An integral value of the square of the voltage V ₅ of the energized waveform at a time ToffSR from the start of falling of the energized waveform to the completion of falling;
The glow plug energization control device is determined based on a calculated effective voltage obtained by dividing a value obtained by dividing the value by a period of the PWM signal and then by a power of 1/2.   2. The glow plug energization control device according to claim 1, wherein the correction value α is determined based on the calculated effective voltage obtained by setting the time TonSR and the time ToffSR to be equal to each other. Energization signal output means for outputting a PWM signal for determining whether or not the glow plug can be energized from the power supply device;
Switching means for switching energization / non-energization to the glow plug based on the PWM signal;
A glow plug energization control device that PWM-controls the power supplied from the power supply device to the glow plug using a duty ratio,
The output voltage of the power supply device is V, the target voltage to be supplied to the glow plug is V _T , the period of the PWM signal is T, and
The time Tondelay from the start of rising of the PWM signal to the start of rising of the energization waveform indicating the voltage supplied to the glow plug, the time TonSR from the start of rising of the energization waveform to the completion of rising, and the start of falling of the PWM signal When the time Toffdelay until the falling start of the energized waveform and the time ToffSR from the start of falling of the energized waveform to the completion of falling are set to the same time TS,
The glow plug energization control device, wherein the duty ratio is determined in accordance with an equation of (V _T / V) ² + (TS / 3T).   4. The energization to the glow plug is controlled using the duty ratio when the temperature of the glow plug is maintained at a predetermined target temperature after the internal combustion engine is started. An energization control device for a glow plug according to item 1.

Images