JP5349195B2 - Glow plug energization control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glow plug power distribution control device suppressing the total amount of current in starting without impairing quick heating performance of a low-rated glow plug. <P>SOLUTION: In this glow plug power distribution control device 1, a DCU (Drive Control Unit) transmits a drive signal to each semiconductor switching element while shifting by (1/n)T<SB>SI</SB>, and an ECU (Electronic Control Unit) includes an initial power distribution processing means S120 performing initial power distribution processing for suppressing the total current in the initial stage of power distribution, and an initial power distribution processing necessity determination means S110 determining the necessity of the initial power distribution processing. The initial power distribution processing means S110 is provided with a temporary duty power distribution means S130 performing power distribution to the glow plug at temporary duty being proportional to (1/n)T<SB>SI</SB>, a duty increase necessity determination means S140 determining the necessity of an increase in the temporary duty Td, and a duty gradually increasing means S150 gradually increasing the temporary duty Td. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a glow plug energization control device that controls energization to a glow plug provided for each cylinder of a diesel combustion engine, and in particular, has a heating element that has a small initial resistance and a resistance value that increases with energization, The present invention relates to a glow plug energization control device that controls energization while suppressing the total amount of current at the time of starting a plurality of low-rated glow plugs that are driven at a rated voltage lower than the rated voltage of the power supply voltage.

  2. Description of the Related Art Conventionally, in a diesel combustion engine, a method of assisting ignition by heating fuel injected into an engine combustion chamber by a glow plug provided for each cylinder for improving startability has been widely practiced. In recent years, in order to improve engine combustion stability and combustion exhaust purification performance, in addition to improving ignitability at engine startup, continuous energization is performed to energize the glow plug after engine startup. .

In a conventional glow plug energization control device, a semiconductor switching element, a drive control unit that controls opening and closing of the semiconductor switching element in accordance with a drive signal from the electronic control device, and a glow plug flows between the semiconductor switching element and the glow plug. The shunt resistor is provided to detect the plug current, and a current detection circuit that detects a current flowing through the glow plug by measuring a voltage drop across the shunt resistor.
When a gate voltage is applied between the gate and source of the semiconductor switching element from the drive control unit in accordance with a drive signal from the ECU, the drain and source of the semiconductor switching element are brought into conduction, and the glow plug is energized.
In the drive control unit, according to the drive signal from the electronic control unit, a plurality of drive signals are transmitted with a predetermined interval shifted, and the heat generation amount of the glow plug is adjusted by changing the duty ratio of the energization cycle to each glow plug. Pulse width modulation (PWM) control is performed.

On the other hand, a low-rated glow having a heating element with a rating lower than the drive voltage (for example, 12 V) (for example, a rating of 7 V for a ceramic glow plug, a rating of 4.7 V for a metal glow plug, etc.) in order to achieve rapid temperature rise and constant energization. A plug is used.
In the conventional glow plug energization control device, immediately after energization, the power supply voltage higher than the glow plug rating is energized with a 100% duty ratio or a relatively large duty ratio, so that the temperature can be raised in a short period of time. It is said.
However, immediately after the start of energization, the resistance value of the heating element is as low as about 0.1 to 0.5Ω, and a large current of about 50 A to 100 A flows as an inrush current.
The resistance value of the heating element rises with the temperature rise of the heating element due to energization, and when the heating temperature is stabilized, the resistance value rises to about several Ω and becomes a low current of about several A to 20A.
Thereafter, PWM control is performed so that the duty ratio of the energization pulse is adjusted with the rated voltage of the heating element to obtain a necessary heat generation amount.

  In Patent Document 1, as a glow plug control device, a plurality of switch means (FET) for switching energization and non-energization of a glow plug to a power supply line for supplying power from a battery to the plurality of glow plugs, and a plurality of switch means off A control device capable of timing control to be in a state is disclosed (see Patent Document 1 FIGS. 1 and 3).

However, when energization is continuously performed on a plurality of loads and inrush currents overlap, the total amount of current flowing through a power source such as a battery becomes extremely large (see Patent Document 1, FIGS. 4 and 5).
For this reason, it is necessary to increase the capacity of the glow relay that protects the glow plug by shutting off the energization to the drive control device in the event of an emergency such as occurrence of overcurrent, short circuit of the semiconductor switching element, or reverse connection of the power source. The physique becomes large and the mountability becomes difficult, which may increase the manufacturing cost.
Also, if the total current at start-up increases, the load on the battery will increase, causing a temporary drop in the battery voltage, and the immediate warming of the glow plug expected by using a low-rated glow plug may not be exhibited. is there.
In particular, when starting at a very low temperature, the internal resistance may increase and the battery capacity may decrease. In such a case, when the inrush currents to the plurality of glow plugs are superimposed and the total current amount is increased, the battery voltage is further lowered, and there is a possibility that a sufficient amount of heat generated by the grooving lugs is not ensured, resulting in misfire.

  Therefore, in view of such circumstances, the present invention, in a glow plug energization control device that controls energization to a plurality of glow plugs provided in a diesel combustion engine, without impairing the quick warming of the low rated glow plug as much as possible. An object of the present invention is to provide a glow plug energization control device capable of suppressing the total current amount at the start.

In the first invention, an electronic control device for controlling operation of the engine by using a plurality of glow plugs provided for each cylinder of a diesel combustion engine as a load and interposing a semiconductor switching element between the power source and each glow plug. A glow plug energization control for controlling energization of the glow plug by providing a drive control unit for generating a drive voltage for opening and closing each semiconductor switching element according to a drive signal transmitted according to the operating status of the engine from In the device
The drive control unit transmits the drive voltage to each semiconductor switching element while shifting the drive cycle of the drive signal by a predetermined interval divided by the number of glow plugs. Initial energization processing means for performing initial energization processing for suppressing the total current, and initial energization processing necessity determination means for determining whether or not the initial energization processing is necessary. Temporary duty energization means for energizing the glow plug with a duty time proportional to the period obtained by dividing the drive period by the number of glow plugs as a temporary duty, and duty increase availability determination means for determining whether the temporary duty can be increased And duty gradually increasing means for gradually increasing the provisional duty (claim 1).

In the second invention, the initial energization processing means sets a processing variable i that changes in accordance with the progress of the processing, and for the number n of the glow plugs, the driving cycle of the driving signal is _TSI , when a Td of the provisional duty time determined by _{Td = i / n · T SI} ( claim 2).

In a third invention, a plug current detecting means for detecting a plug current flowing through the glow plug is provided between the power source and the glow plug,
The initial energization process necessity determination means determines whether or not the initial energization process is necessary by comparing the plug current and the plug current threshold.

  In the fourth invention, the duty increase possibility determination means determines whether the provisional duty can be increased by comparing the plug current detected by the plug current detection means with a plug current threshold.

  In a fifth aspect of the invention, the initial energization processing means includes plug current threshold gradually decreasing means for gradually decreasing the plug current threshold by the processing variable i.

In the sixth invention, when the plug current threshold gradual reduction means sets the plug current threshold I _(i) for the processing variable i to be the maximum inrush current per plug I _MAX , I _(i) = 1 / (I + 1) · I _MAX is calculated (claim 6).

  In the seventh invention, the initial energization process necessity determination means includes an elapsed time measurement means for measuring an elapsed time from the start of the initial energization process, and an initial value is obtained by comparing the elapsed time with an elapsed time threshold. Whether energization processing is necessary or not is determined (claim 7).

  In the eighth invention, the duty increase possibility determination means determines whether or not the provisional duty can be increased by comparing the elapsed time with an elapsed time threshold.

  In a ninth aspect of the invention, the initial energization processing means includes elapsed time threshold gradually increasing means for gradually increasing the elapsed time threshold by the processing variable i.

In the tenth invention, the elapsed time threshold gradually increasing means calculates the elapsed time threshold t _(i) for the processing variable i by t _(i) = 0.5 · i (claim 10).

According to the present invention, since the energization to the plurality of glow plugs is driven by the temporary duty while being shifted by the predetermined interval by the initial energization processing means, the plug plug current flowing through each glow plug is superimposed at the initial energization. In other words, the total amount of current flowing through the power source is suppressed to an inrush current of about one glow plug. In addition, when the duty increase enable / disable determining unit determines that the duty can be increased, the duty can be gradually increased by the duty gradually increasing unit, so that the increase in the total current amount can be suppressed promptly. The temperature of the glow plug can be raised to a desired temperature.
Further, when the initial energization process necessity determination means determines that the initial energization process is unnecessary, the process immediately proceeds to the normal energization process.

The circuit diagram which shows the outline | summary of the glow plug electricity supply control apparatus in embodiment of this invention. The flowchart which shows the electricity supply control method of the glow plug electricity supply control apparatus in embodiment of this invention. The specific example of the initial electricity supply process necessity determination process of the glow plug electricity supply control apparatus in the 1st Embodiment of this invention is shown, (a) is a flowchart at the time of using engine water temperature as a criterion, (b) is plug current. The flowchart in the case of using as a criterion. The specific example of the initial electricity supply process of the glow plug electricity supply control apparatus in embodiment of this invention is shown, (a) is a flowchart, (b) is the duty time with respect to the process variable i at the time of applying this invention to a 4-cylinder engine. A table showing Td and determination threshold value I (i). The other specific example of the initial stage energization process of the glow plug energization control apparatus in embodiment of this invention is shown, (a) is a flowchart, (b) is with respect to the process variable i at the time of applying this invention to a 4-cylinder engine. A table showing duty time Td and determination threshold value t (i). The time chart which shows the operation | movement of the initial stage energization process of the glow plug energization control apparatus in embodiment of this invention. The characteristic view which shows the effect with respect to total current suppression of this invention with a comparative example. (A) is a characteristic view which shows the effect with respect to the battery voltage fall suppression of this invention with a comparative example, (b) is a characteristic diagram which shows the effect with respect to the battery capacity fall of this invention with a comparative example. The characteristic view which shows the effect of the other Example of this invention. The characteristic view which shows the effect with respect to the temperature increase rate of this invention with a comparative example.

As an embodiment of the present invention, a glow plug 50 (GL ₁ , GL ₂ , GL ₃ , GL ₄ ) provided for each cylinder of a diesel combustion engine (not shown) is used as a load, and a power source 10 such as a battery and the glow plug 50 are connected. Glow plug energization control for controlling energization and shut-off of the glow plug 50 by controlling opening and closing of semiconductor switching elements T ₁ , T ₂ , T ₃ , T ₄ such as MOSFETs and IGBTs interposed as switching means. An outline of the apparatus 1 will be described with reference to FIG.
In this embodiment, a four-cylinder engine will be described as an example of a diesel combustion engine provided with four glow plugs 50, but the present invention is not limited to this embodiment.

  The glow plug energization control device 1 energizes the glow plug 50 in accordance with a drive signal SI from the ECU 30 according to the operation status of the engine, and an electronic control unit (ECU) 30 that controls the operation of the diesel combustion engine. And a glow plug control unit (GCU) 40 to be controlled.

GCU40 includes a drive control unit (DCU) 41, a self-diagnostic unit (DIU) 42, a semiconductor switching element _{T 1, T 2, T 3} , T 4, the self-diagnosis information detecting section _{S 1,} S 2, _{S 3} It is constituted by the _{S 4.}
The DCU 41 uses the drive signals G ₁ , G ₂ , G ₃ , and G ₄ that open and close the semiconductor switching elements T ₁ , T ₂ , T ₃ , and T ₄ according to the drive signal SI, and sets the pulse period T _SI of the drive signal SI. Pulses that are transmitted while being shifted by a predetermined period divided by the number of loads (in this embodiment, ¼ T _SI ), and changing the duty ratio of the energization cycle to each glow plug 50 to adjust the heat generation amount of the glow plug Width modulation (PWM) control is performed. In the present embodiment, the drive signals SI, G ₁ , G ₂ , G ₃ , and G ₄ are shown with the high output level on and the low output off. It can be changed as appropriate.
Self-diagnosis information detecting section _{S 1, S 2, S 3} , S 4 _, the plug current _I GL1 flowing through the glow plugs _{50, I GL2, I GL3,} I GL4 and the semiconductor switching elements _{T 1,} T 2, _{T 3} , Self-diagnosis information D ₁ , D ₂ , D ₃ , D ₄ indicating the state of the glow plug 50 such as the output potential of T ₄ is detected.
The DIU 42 diagnoses the state of the glow plug drive system according to the self-diagnosis information D ₁ , D ₂ , D ₃ , D ₄ and transmits a self-diagnosis signal DI to the ECU 30.

The voltage of the power supply 10 is adjusted to a control voltage + B (for example, 5V) and a drive voltage BATT (for example, 12V) by a power supply adjustment circuit (not shown).
The control voltage + B is supplied to the ECU 30 and the GCU 40 via the fuse 201 and the main relay (MRY) 20, and the drive voltage BATT is supplied to the GCU 40 via the fuse 211 and the glow relay (GRY) 21. .

When the main switch 11 is closed, the main relay MRY20 is closed and the control voltage + B is supplied to the ECU 30 and the GCU 30.
At the same time, the glow relay GRY21 is closed and the drive voltage BATT is supplied to the GCU 30.
The ECU 30 includes an engine water temperature Tw, a crank angle CA, a rotational speed Ne, a throttle opening detected by an operating condition detecting means such as a water temperature sensor, a crank angle sensor, a rotation speed sensor, a throttle sensor, and a glow plug temperature sensor (not shown). Information indicating the operation state of the engine such as SL and glow plug temperature Tg is input, and a drive signal SI in which a duty ratio is calculated to adjust the heat generation amount of the glow plug 50 to a desired value is transmitted.
At this time, in the glow plug energization control device 1 of the present invention, according to the energization control method described later, the temperature and initial resistance of the glow plug 50 are low, and in the initial energization in which a large inrush current flows, a plurality of glow plugs 50 are used. In order to prevent a large inrush current from overlapping with each other, the drive signal SI whose duty ratio is adjusted by the initial energization process is set to suppress the total current flowing through the power supply 10.
Alternatively, the drive signal SI may be adjusted by feeding back the detection results of the plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 flowing through each glow plug 50 to the ECU 30.
Further, when the DIU 42 sends a self-diagnosis signal DI indicating the occurrence of any abnormality such as overcurrent detection, switching element short circuit, or disconnection to the ECU 30, the glow relay GRY21 is opened and the power supply to the GCU 40 is cut off. The glow plug 50 and the semiconductor switching elements T ₁ , T ₂ , T ₃ , T ₄ are protected.

The energization control method of the glow plug energization control device 1 in the embodiment of the present invention will be described with reference to FIG.
When main relay MRY is closed and energization control to glow plug 50 is started in step S100, first, the necessity of initial energization processing is determined by the initial energization processing necessity determination means in step S110. A specific initial energization processing necessity determination method will be described later.
If it is determined in step S110 that the initial energization process is necessary, the process proceeds to Yes, and the initial energization process is started by the initial energization processing means in steps S120 to S170. At this time, i = 1 is set for the process variable i that changes depending on the progress of the process.
When it is determined that the initial energization process is unnecessary, such as at the time of restart, the process proceeds to No, and the normal rated duty energization process after step S200 is performed.
In step S120, initial energization processing is started, and energization of the glow plug 50 is started in the provisional duty energization means in step S130 by the provisional duty time Td.
Provisional duty time Td, to the period _{T SI} of the drive signal SI, when the number of the glow plug 50 is _n, the value n of the i of _{T SI} is set _{(Td ← i / nT SI)} .
For example, in this embodiment, is provided a glow plug 50 is present 4, at the initial energization start, since it is i = 1, n = 4, the provisional duty time Td = 1 / _{4T SI,} i.e., the provisional 25% Energization of the glow plug 50 is started at the duty ratio.
In the duty increasing / decreasing determining means in step S140, it is determined whether or not the duty ratio may be increased. A more specific duty increase availability determination processing method will be described later.
If it is determined in step S140 that the duty ratio cannot be increased, the process proceeds to No, and energization while maintaining the provisional duty ratio in step S130 is repeated.
If it is determined in step S140 that the duty ratio can be increased, the process proceeds to Yes, and the process of increasing the process variable i to i + 1 to increase the duty ratio stepwise by the duty gradually increasing means in step S150. Is made.
It is determined whether or not the initial energization process can be ended by the initial energization process end possibility determination process in step S160.
If it is determined in step S160 that the initial energization end is impossible, the process proceeds to No, and the duty time Td determined by the process variable i increased by the duty ratio gradual increase process in step S150. Is energized.
Specifically, for example, if the process variables i is increased to 2, the duty time _{Td = 2 / 4T SI = 1} / 2T SI, i.e., so that the energization duty ratio of 50% is performed.
Steps S130 to S160 are repeated until it is determined by the initial energization end possibility determination process of step S160 that the initial energization process can be completed, and whenever it is determined in step S140 that the duty can be increased, A process of increasing the process variable i is performed by the duty gradual increase process of step S150, and energization is performed while the provisional duty time Td is increased stepwise in step 130.
If it is determined by the initial energization process end possibility determination process in step S160 that the initial energization process can be ended, the process proceeds to Yes, and the initial energization process is ended in S170. More specific initial energization end possibility determination processing will be described later.
When the initial energization process is completed, a normal energization process is performed in accordance with the drive signal SI transmitted from the ECU 20 in accordance with the engine operating status by the rated duty energization process in step S200.
In the rated duty energization process, the ECU 30 detects the engine water temperature Tw, the crank angle CA, and the rotation speed detected by the operating condition detection means such as a water temperature sensor, a crank angle sensor, a rotation speed sensor, a throttle sensor, and a glow plug temperature sensor (not shown). A duty ratio of the drive signal SI is set on the basis of information indicating the operation state of the engine such as Ne, throttle opening SL, glow plug temperature Tg, and the like, and a plurality of currents that control energization to each glow plug 50 are controlled according to the drive signal SI. Drive signals G ₁ , G ₂ , G ₃ , G ₄ are transmitted and energization is performed with the duty ratio adjusted by the rated voltage (for example, 7 v) of the glow plug 50. In the rated duty energization process, the transmission intervals of the plurality of drive signals G ₁ , G ₂ , G ₃ , G ₄ are maintained at 1 / n of the cycle T _SI of the drive signal SI.
The rated duty energization process of S200 is repeated until it is determined in the energization end determination process of step S210 that energization of the glow plug 50 is unnecessary.
If the main switch 11 is opened and the energization end determination process in step S210 determines that energization of the glow plug 50 is unnecessary, the process proceeds to Yes, and energization of the glow plug 50 is terminated in S220.

With reference to FIG. 3, some specific examples of the initial energization process necessity determination process will be described.
In the embodiment shown in FIG. 3A, it is determined whether or not the initial energization process is necessary based on the engine water temperature Tw detected by a water temperature sensor provided as an operation state detecting means for detecting the operation state of the engine.
As shown in FIG. 3A, when the initial energization process necessity determination process is started in step S110, the engine water temperature Tw is detected in the operation state detection process in step S111, and the initial energization process necessity determination in step S112. In the means, the engine water temperature Tw is compared with the threshold value T _0, and when the engine water temperature Tw is lower than the threshold value T ₀ (for example, 25 ° C.), it is determined that the engine is starting, and the process proceeds to Yes. The initial energization process of step S120 is performed.
In step S112, when the engine coolant temperature Tw is higher than the threshold value T ₀ is determined to be a time of re-energized, the process proceeds to No, the initial energization process required the determination in step S114 is performed, the rated duty energization process of step S200 is performed.

As shown in FIG. 3B, the plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 that flow through the glow plug 50 when determining whether or not the initial energization process is necessary may be used as a reference.
The plug currents I _GL1 , I _GL2 , I _GL3 , I _GL4 are self-diagnostic information detection units S ₁ provided as current detection means between the switch means T ₁ , T ₂ , T ₃ , T ₄ and the glow plug 50. , S ₂ , S ₃ , S ₄ .
Specifically, a shunt resistor (for example, a resistor of several tens of mΩ to several hundred mΩ) whose resistance value is accurately adjusted is provided, and measurement is performed by detecting a voltage drop across the shunt resistor, or current detection is performed. A sensor can be provided or measured by other known current detection methods.
The plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 may be used as abnormality detection in the drive system as the self-diagnosis information D ₁ , D ₂ , D ₃ , and D ₄ .
Further, the reading of the plug currents I _GL1 , I _GL2 , I _GL3 , I _GL4 is performed when a predetermined time (for example, one half of the duty time Td) elapses from the rise of the drive signals G ₁ , G ₂ , G ₃ , G _4. It is desirable to do it.
If in step S110a initial energization process necessity determination is initiated, to detect the plug current _{I GL1, I GL2, I GL3} , I GL4 by the plug current detecting means in step S111a, the initial energization process necessity determination process in step S112a Is compared with the plug currents I _GL1 , I _GL2 , I _GL3 , I _GL4 and a threshold value I ₀ (for example, 50 A), and when the plug currents I _{GL 1} , I _{GL 2} , I _GL3 , I _GL4 are higher than the threshold value I ₀ , It is determined that the temperature of the plug is low and the engine is in a starting state, the process proceeds to Yes, the initial energization process necessity determination in step S113a is performed, and the initial energization process in step S120 is performed.
In step S112a, when the plug current _{I GL1, I GL2, I GL3} , I GL4 is lower than the threshold, higher temperature of the glow plug 50, is determined to be a time of re-energized, the process proceeds to No, the initial energization process in step S114a An unnecessary determination is made, and the rated duty energization process of step S200 is performed.

A specific example of the initial energization processing method will be described with reference to FIG.
In the present embodiment, measured plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 are used to determine whether or not the provisional duty can be increased.
In step S120a, initial energization processing is started. At this time, the processing variable i = 1 is set. Also, counting of the elapsed time t from the start of energization is started.
In the provisional duty energization process in step S130a, energization to the glow plug 50 is started by the provisional duty time Td.
Provisional duty time Td at this time, with respect to the period _{T SI} of the drive signal SI, when the number of the glow plug 50 is _n, the value n of the i of _{T SI} is set (Td ← i / _{nT SI} ).
For example, in the present embodiment, four glow plugs 50 are provided, and at the start of initial energization, i = 1 and n = 4. Therefore, the duty time Td = 1 / 4T _SI , that is, the drive cycle T _SI Energization of the glow plug 50 is started with a temporary duty ratio of 25%.
Next, in the plug current measurement process of step S131a, plug currents IGL1 _(t) , _{IGL2 (t)} , _{IGL3 (t)} , IGL that flow through each glow plug 50 when t (sec) has elapsed since the start of the initial energization process. _{GL4 (t)} is measured.
The duty increase determination processing in step S140a, whether may increase the duty ratio plug current _{I GL1 (t), I GL2} (t), I GL3 (t), I GL4 (t) and process variables Judgment is made by comparison with the plug current threshold I _(i) for _i .
At this time, the plug current threshold I _(i) is a value defined by I _(i) = 1 / (i + 1) · I _MAX with respect to the maximum inrush current I _MAX (for example, 100 A) flowing per 501 glow plugs. Is calculated and selected.
If it is determined in step S140a that the duty ratio cannot be increased, the process proceeds to No, and energization while maintaining the temporary duty ratio in step S130a is repeated.
If it is determined in step S140a that the duty ratio can be increased, the process proceeds to Yes, and processing for increasing the process variable i to i + 1 is performed by the duty gradually increasing process in step S150a in order to increase the duty ratio. .
It is determined whether or not the initial energization process can be ended by the initial energization process end possibility determination process in step S160a.
If it is determined in step S160 that the initial energization end is impossible, the process proceeds to No, and the duty time Td determined by the processing variable i increased by the duty ratio gradual increase process in step S150a. Energization is performed.
Specifically, as shown in FIG. 4B, in the present embodiment, for the processing variable i = 1, 2, 3, 4, the duty time Td is 25% T _SI , 50% T _SI. , 75% T _SI , 100% T _SI are sequentially set, and plug current threshold I _(i) is sequentially set to 50 A, 33 A, 25 A, and 20 A.
As described above, as the process variable i increases, the duty time Td of the energization pulse to the glow plug 50 is increased stepwise, and the plug current threshold I _(i) for determining whether the duty ratio can be increased is the process variable i. Is gradually decreased by the plug current threshold gradual decrease means as it is sequentially increased.
A constant duty time Td is maintained until the plug current threshold I _(i) is reduced below the predetermined plug current threshold I _(i) , and when the plug current threshold I _(i) is decreased below the predetermined plug current threshold I _(i) , the duty time Td is increased stepwise. In addition, the plug currents _{IGL1 (t)} , _{IGL2 (t)} , _{IGL3 (t)} , and _{IGL4 (t)} are reduced.
In the initial energization end possibility determination process in step S160a, the plug currents IGL1 _(t) , _{IGL2 (t)} , _{IGL3 (t)} , and _{IGL4 (t)} are the end determination threshold _values I _E (20A in this embodiment). It is determined that the initial energization process can be ended depending on whether or not the following is true.
Plug current _{I GL1 (t), I GL2} (t), I GL3 (t), until _{I GL4 (t)} is completed determination threshold I _{E hereinafter,} the process of step S130a~S160a is repeated, in step S140a Every time it is determined that the duty can be increased, the process variable i is increased by the duty gradual increase process of step S150a, and the provisional duty time Td of step 130a is gradually increased.
If it is determined by the initial energization process end possibility determination process in step S160a that the initial energization process can be completed, the process proceeds to Yes, and the initial energization process is terminated in S170a.
In this way, as the plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 are decreased, the duty ratio is gradually increased by the duty gradual increase process for gradually increasing the duty ratio, thereby reducing the large rating of the inrush current. When a plurality of glow plugs 50 are energized, the temperature can be raised to a predetermined temperature relatively quickly while suppressing a rapid increase in the total current.
Further, since the duty time Td is increased stepwise in accordance with changes in the actual plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 , it is possible to deal with individual states of the glow plug 50.
When the drop speeds of the plug currents _IGL1 , _IGL2 , _IGL3 , and _IGL4 are fast, it is possible to shift to the rated duty energization earlier, and the drop of the plug currents _IGL1 , _IGL2 , _IGL3 , and _IGL4 . When the speed is low, the gradually increasing speed of the provisional duty time is also slowed, so that the glow plug 50 can be heated while always suppressing the total current amount.

A specific example of another initial energization processing method will be described with reference to FIG.
In the above embodiment, the energization duty time Td of the glow plug 50 is increased based on changes in the actual plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 , but in this embodiment, the actual plug current is detected. Without reducing the plug current from the elapsed time t measured by the elapsed time measuring means for measuring the elapsed time from the start of the initial energization process, and the duty time Td is increased stepwise as the elapsed time t increases. As a result, the temperature of the glow plug 50 can be quickly raised while suppressing the total amount of current.
In step S120b, initial energization processing is started. At this time, the processing variable i is set to 1, and counting of the elapsed time t from the start of energization is started.
In the provisional duty energization process in step S130b, energization to the glow plug 50 is started by the provisional duty time Td.
Provisional duty time Td at this time, with respect to the period _{T SI} of the drive signal SI, when the number of the glow plug 50 is _n, the value n of the i of _{T SI} is set (Td ← i / _{nT SI} ).
In the duty increase / decrease determination process in step S140b, it is determined whether or not the duty ratio may be increased by comparing the elapsed time t with the elapsed time threshold t _(i) for the process variable i.
At this time, as the elapsed time threshold t _(i) , a value calculated by t _(i) = 0.5 · i is selected as the elapsed time threshold gradual increase means for the processing variable i.
If it is determined in step S140b that the duty ratio cannot be increased, the process proceeds to No, and energization while maintaining the provisional duty ratio in step S130b is repeated.
If it is determined in step S140b that the duty ratio can be increased, the process proceeds to Yes, and processing for increasing the process variable i to i + 1 is performed by the duty gradually increasing process in step S150b to increase the duty ratio. .
In the initial energization processing end determination process in step S160b, the elapsed time t and the initial energization processing end time comparison with t _E, whether it may terminate the initial energization process is determined.
If it is determined in step S160b that the initial energization end is impossible, the process proceeds to No and energization is performed by the duty time Td determined by the process variable increased by the duty ratio gradual increase process in step S150b. Is done.
Specifically, as shown in the figure (b), in the present embodiment, the processing variable i = 1, 2, 3, 4, the duty time _{Td, 25% T SI, 50} % TS I 75% T _SI and 100% T _S I are sequentially set, and the elapsed time threshold t _(i) is sequentially set to 0.5 sec, 1.0 sec, 1.5 sec, and 2.0 sec. The
In this way, the duty time Td of the energization pulse to the glow plug 50 is increased stepwise as the processing variable i increases, and the elapsed time threshold t _(i) for determining whether the duty ratio can be increased is also stepwise. Therefore, the constant duty time Td is maintained until the predetermined elapsed time threshold value t _(i) elapses, and when the predetermined elapsed time threshold value t _(i) elapses, the duty time Td increases stepwise. Is done.
In the initial energization end possibility determination process in step S160b, the initial energization process can be ended depending on whether or not the elapsed time threshold t (i) is equal to or greater than the end determination threshold t _E (2.0 sec in this embodiment). It is determined that there is.
Until the elapsed time threshold t (i) becomes equal to or greater than the end determination threshold t _E (2.0 sec in the present embodiment), the processing of steps S130b to S160b is repeated, and it is determined in step S140b that the duty can be increased. Every time, the process variable i is increased by the duty gradual increase process of step S150b, and the provisional duty time Td of step 130b is gradually increased.
In this way, the plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 are regarded as decreasing with the passage of the energization time t, and the duty is gradually increased by the duty gradual increase process that increases the duty ratio stepwise. By increasing the ratio, it is possible to raise the temperature to a predetermined temperature relatively quickly while suppressing a rapid increase in the total current when a plurality of low-rated glow plugs 50 having a large inrush current are energized.
In the present embodiment, there is no need to measure the plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 with respect to the initial energization process, and there is an advantage that the calculation load of the ECU 30 can be reduced and the configuration can be simplified.

With reference to FIG. 6, the operation | movement in the initial stage process of the glow plug electricity supply control apparatus of this invention is demonstrated.
In the initial energization process, as shown in the figure (a), the ECU 30 sends a DCU 41 a 25% duty period (indicated as 25% dty in the figure) with a driving time of 25% of the pulse period, and a driving time. 50% duty period (denoted as 50% dty in the figure) with 75% of the pulse period, 75% duty period (denoted as 75% dty in the figure) with the driving time as 75% of the pulse period, and driving time Is a 100% duty period (indicated as 100% dty in the figure), and a drive signal SI that gradually increases the duty ratio is transmitted.
In DCU41 by receiving a driving signal transmitted from the ECU 30, as shown in the figure (b) ~ (e), the same waveform as the drive signal SI, the glow while shifting by one cycle of 4 min drive cycle _{T SI} Drive signals G ₁ , G ₂ , G ₃ , G ₄ are transmitted to switch means T ₁ , T ₂ , T ₃ , T ₄ for controlling energization to the plug 50.
As a result, the plug currents I _GL1 , I _GL2 , I _GL3 , and I _GL4 flowing through the glow plugs 50 are driven signals G ₁ , G ₂ , G ₃ , G, as shown in FIGS. ₄ is a pulse current synchronized with ON / OFF of ₄ .

The effect of the present invention will be described with reference to FIG. If as a comparative example 1, it was carried out by one cycle of 4 min staggered 100% duty energization of conventional glow plug electrification control apparatus, such as those used by the drive pulse period T _SI energization start timing for each glow plug Indicates the battery current.
An inrush current of about 80 A at the maximum flows through each glow plug 50.
However, if the glow plug energization control device 1 of the present invention is used, the drive signals G ₁ , G ₂ , G ₃ , and G ₄ for driving the glow plugs by the above-described initial energization process have a low duty ratio (for example, 25%). In addition, since each glow plug 50 is driven by being shifted by a predetermined interval (1/4 T _SI ), the plug currents I _GL1 , I _GL2 , I _GL2 , I _GL3 , I _GL4 flowing through each glow plug 50 are As shown in a circle A in the figure, they do not overlap each other. Therefore, the total current amount is suppressed to the same level as the inrush current for one glow plug. Further, when the plug currents I _GL1 , I _GL2 , I _GL2 , I _GL3 , and I _GL4 flowing through the glow plugs 50 with energization decrease, the duty ratio is gradually increased, and the plug currents I _GL1 , I _GL2 , I _GL2 , Although a part of I _GL3 and I _GL4 is superimposed, the total current amount does not exceed the inrush current for one glow plug.
On the other hand, in the case of the conventional glow plug energization device shown as the comparative example 1, even if energization to the glow plug is started while shifting by a quarter cycle, the energization to the next glow plug is not performed until the inrush current is not reduced. Therefore, a large current of 200 A to 400 A flows as the total amount of current flowing through the battery. For this reason, the glow relay GRY21 must have a large capacity.
In addition, in the case of the conventional glow plug energization device, since the total current amount at the time of starting is extremely large, it becomes difficult to detect overcurrent, or the difference from the case where the current of several A is controlled in the rated duty energization is large. There is a risk that current cannot be measured accurately over a wide current width.
According to the present invention, since the total current amount at the start is low and the difference from the overcurrent is clear, the overcurrent detection is facilitated, and the difference between the total current amount at the start and the total current amount at the rated duty energization is also achieved. Since it becomes smaller, more accurate current detection is possible.

With reference to FIG. 8, the effect with respect to the fall of the battery voltage of this invention is demonstrated. As illustrated in FIG. 1A as Example 1, in the glow plug energization control device of the present invention, since the total inrush current at the time of starting is suppressed, the drop in battery voltage is small.
On the other hand, as shown as Comparative Example 1 in FIG. 5A, in the conventional glow plug energization control device, since the total inrush current at the start is extremely large, a large drop in the battery voltage is recognized. Further, when the battery capacity is reduced, such as at an extremely low temperature, the glow plug energization control device of the present invention has a small difference from the normal battery capacity as shown in Example 1 in FIG.
On the other hand, when the battery capacity is reduced, such as at extremely low temperatures, the conventional glow plug energization control device increases the burden on the battery, and as shown in Comparative Example 1 in FIG. The difference becomes larger.
When the power supply capacity is not sufficient, in conventional glow plug energization control devices that place a heavy burden on the battery, the temperature rise rate becomes slow due to a sudden drop in the battery voltage, and the expected speed by using a low rated glow plug. There is a risk that the warmth will be lost.
Therefore, according to the present invention, the initial energization process is performed at the time of starting, so that the speed at which the temperature of the glow plug rises is slowed, but the burden on the battery is reduced. On the other hand, it can be expected that the temperature of the glow plug can be raised faster than the conventional glow plug energization control device.

With reference to FIG. 9, another embodiment of the present invention will be described. In the above embodiment, the provisional duty Td and so 25% → 50% → 75% → 100%, by gradually increasing from 1 / n · _{T SI} is inversely proportional to the number n of glow plugs 50, reliably Although the total amount of current is suppressed, when the battery capacity of the power source 10 has a margin or when the capacity of the glow relay GRY21 is large, as shown in the second embodiment, 50% → 75% → 100 % And the duty ratio may be gradually increased, or as shown in the third embodiment, the initial energization control may be performed such that the duty ratio is gradually increased from 50% to 100%.
By adopting such control, it is possible to take advantage of the rapid temperature rise that is an advantage of the low-rated glow plug while suppressing the sudden decrease in battery voltage by suppressing the total amount of current flowing through the battery to some extent.

With reference to FIG. 10, the effect on the glow plug temperature rise characteristic of the glow plug energization control device of the present invention will be described. This figure shows the temperature rise characteristics of the glow plug with the temperature of the glow plug as the vertical axis and the elapsed time from the start of energization as the horizontal axis.
Comparative Example 1 shows the temperature rise characteristic of one glow plug when energized with 100% duty at the start, as is generally done in conventional glow plug energization control devices. FIG. 5 shows the temperature rise characteristics when energization is simultaneously started with four glow plugs at 100% duty and a sudden drop in battery voltage is caused.
Example 1 is a temperature rise characteristic when the duty ratio is gradually increased from 25% → 50% → 75% → 100% at the time of starting for four glow plugs by using the glow plug energization control device of the present invention. Example 2 shows a temperature rise characteristic when the duty ratio is gradually increased from 50% → 75% → 100% at the time of start for four glow plugs using the glow plug energization control device of the present invention. Example 3 shows a temperature rise characteristic when the duty ratio is gradually increased from 50% to 100% at the time of start for four glow plugs using the glow plug energization control device of the present invention.

DESCRIPTION OF SYMBOLS 1 Glow plug energization control apparatus 10 Power supply 20, 21 Relay 201, 211 Fuse 30 Electronic control unit (ECU)
40 Glow plug energization control unit (GCU)
41 Drive control unit (DCU)
42 Self-diagnosis device (DIU)
50 Glow plug (load)
+ B Control voltage BATT Drive voltage T ₁ , T ₂ , T ₃ , T ₄ Semiconductor switching element (switch means)
SI, G ₁ , G ₂ , G ₃ , G ₄ drive signals S ₁ , S ₂ , S ₃ , S ₄ current detection means DI self-diagnostic signals D ₁ , D ₂ , D ₃ , D ₄ self-diagnosis information I _GL1 , I _GL2 , I _GL3 , I _GL4 Plug current I _(i) Plug current threshold i Process variable t Elapsed time t _(i) Elapsed time threshold S100 Energization control start S110 Initial energization process necessity determination process S120 Initial energization process S130 Provisional duty energization Process S140 Duty increase enable / disable determination process S150 Duty gradually increasing energization process S160 Initial energization process end enable / disable determination process S170 Initial energization process end S200 Rated duty energization process S210 Energization end determination process S220 Energization end

JP 2008-31979 A

Claims (10)

The operation status of the engine from an electronic control unit that controls the operation of the engine by interposing a semiconductor switching element between the power source and each glow plug with a plurality of glow plugs provided for each cylinder of the diesel combustion engine as a load In a glow plug energization control device for controlling energization to the glow plug by providing a drive control unit for generating a drive voltage for opening and closing each semiconductor switching element according to a drive signal transmitted according to
The drive control unit transmits the drive voltage to each semiconductor switching element while shifting the drive cycle of the drive signal by a predetermined interval divided by the number of glow plugs,
The electronic control device is
Initial energization processing means for performing initial energization processing for suppressing the total current at the initial energization;
An initial energization process necessity determination means for determining whether or not the initial energization process is necessary,
The initial energization processing means is
Provisional duty energization means for energizing the glow plug with a duty time proportional to a period obtained by dividing the drive period of the drive signal by the number of glow plugs as a provisional duty;
Duty increase availability determination means for determining whether the provisional duty can be increased;
A glow plug energization control device comprising duty gradually increasing means for gradually increasing the provisional duty. The initial energization processing means sets a process variable i that changes according to the progress of the process, and for the number n of the glow plugs, the drive cycle of the drive signal is _TSI , and the provisional duty time is Td When
The glow plug energization control apparatus according to claim 1, determined by _{Td = i / n · T SI} . A plug current detecting means for detecting a plug current flowing through the glow plug is provided between the power source and the glow plug,
The glow plug energization control device according to claim 1 or 2, wherein the initial energization processing necessity determination means determines whether or not the initial energization processing is necessary by comparing the plug current and a plug current threshold. 4. The glow plug energization control device according to claim 3, wherein the duty increase possibility determination means determines whether the provisional duty can be increased by comparing the plug current detected by the plug current detection means with a plug current threshold. The glow plug energization control device according to claim 3 or 4, wherein the initial energization processing means includes plug current threshold gradually decreasing means for gradually decreasing the plug current threshold by the processing variable i. When the plug current threshold gradually decreasing means sets the plug current threshold I _(i) for the processing variable i to be the maximum inrush current per plug, I _MAX ,
6. The glow plug energization control device according to claim 5, wherein the glow plug energization control device is calculated by I _(i) = 1 / (i + 1) · I _MAX . The initial energization process necessity determination means comprises an elapsed time measuring means for measuring an elapsed time from the start of the initial energization process,
The glow plug energization control device according to any one of claims 1 to 6, wherein the necessity determination of the initial energization processing is performed by comparing the elapsed time with an elapsed time threshold.   The glow plug energization control device according to claim 7, wherein the duty increase enable / disable determining unit determines whether the provisional duty can be increased by comparing the elapsed time with an elapsed time threshold.   The glow plug energization control device according to claim 7 or 8, wherein the initial energization processing means includes elapsed time threshold gradually increasing means for gradually increasing the elapsed time threshold by the processing variable i. The elapsed time threshold gradual increase means sets an elapsed time threshold t _(i) for the process variable i,
The glow plug energization control device according to claim 9, which is calculated by t _(i) = 0.5 · i.

Images