JPH1182125A - Electric load driving device and fuel injection valve driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric load driving device that can improve flexibility of design and manufacturing efficiency without needing to provide a radiating member at a driving element for making a current flow to electric load. SOLUTION: All fuel injection valves are simultaneously opened by making an exciting current flow every rotation of an engine simultaneously to four parallel- connected exciting coils L1-L4 respectively provided at the fuel injection valves for every cylinder. A simultaneous injection type engine control electronic control unit(ECU) 1 openes all fuel injection valves simultaneously by making an exciting current flow every rotation of an engine simultaneously to four parallel-connected exciting coils L1-L4 respectively provided at the fuel injection valves for every cylinder. This ECU 1 is provided with four transistors Tr1-Tr4 connected in parallel with one another and series-connected to an exciting coil group composed of the parallel-connected exciting coils L1-L4. The respective transistors Tr1-Tr4 are switched in regular order and turned on every rotation of the engine to make the exciting current flow to the exciting coils L1-L4. As a result, power consumption of the respective transistors Tr1-Tr4 is remarkably reduced, so that there is no need to fit a radiating member such as a radiating fin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric load driving device for supplying a current to an electric load and a fuel injection valve driving device for driving a fuel injection valve for injecting fuel into an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, a simultaneous injection system has been known as one of the fuel injection systems for an automobile engine, for example. This simultaneous injection method is also referred to as a simultaneous injection method, and is performed at every rotation of the engine (that is, when the crankshaft of the engine is 36 times).
This is a method in which fuel injection is started once for every cylinder at a predetermined crank angle once each time the cylinder rotates 0 °.

In an electronic control unit for injecting fuel into an engine by such a simultaneous injection system, as shown in FIG. 6, a plurality of fuel injection valves for injecting fuel into the engine are connected to one driving transistor. The valve 21 is simultaneously driven to open the valve. FIG. 6 shows the case of a four-cylinder engine.

More specifically, in this type of electronic control device, a plurality (four) of excitation coils La, Lb, and L4 are provided in a fuel injection valve of each cylinder and connected in parallel with each other.
One driving transistor 21 is connected in series to the excitation coil group composed of Lc and Ld. And
CPU (microcomputer) that controls the engine
23 supplies a base current to the driving transistor 21 via the output circuit 25 every time the crankshaft of the engine makes one revolution, and operates the driving transistor 21 for an energizing time according to the operating state of the engine ( By turning it on, the current is simultaneously supplied to the exciting coils La to Ld for the above-mentioned energizing time, whereby the fuel injection valves of the respective cylinders are simultaneously opened and fuel is injected into the engine.

[0005]

Here, as shown in FIG. 6, if the current is applied to the exciting coils La to Ld by one driving transistor 21, the power consumption of the driving transistor 21 is naturally increased. Under the worst conditions, the junction temperature of the driving transistor 21 exceeds its maximum rating (generally, 150 ° C.).

For this reason, in the conventional device, a heat radiating member such as a heat radiating fin is attached to the driving transistor 21 so that the junction temperature of the driving transistor 21 does not exceed the maximum rating. However, the provision of heat-radiating members such as heat-radiating fins restricts the layout of components in the device and the external materials of the device (materials of the printed circuit board and the case) and lowers the component mounting density. . Moreover, in general, it is difficult to automatically mount a heat-radiating member such as a heat-radiating fin, so that the number of assembling steps of the device increases.

[0007] Such a problem applies not only to a device for driving a fuel injection valve but also to a device for energizing another electric load such as an electric motor or a lamp. The present invention has been made in view of such a problem, and does not require a special heat-dissipating member to be provided for a drive element that passes a current to an electric load, and can improve design flexibility and manufacturing efficiency. It is a first object to provide a fuel injection valve driving device capable of improving design flexibility and manufacturing efficiency similarly to the electric load driving device. And

[0008]

Means for Solving the Problems and Effects of the Invention In order to achieve the first object, in the electric load drive device according to the first aspect of the present invention, a plurality of drives connected in parallel to each other are provided. The element is connected in series to the electric load, and the energization control means gives a command to any of the plurality of drive elements to operate the drive element, thereby energizing the electric load. . In particular, the energization control means is configured to sequentially switch the driving element to be operated among the plurality of driving elements.

That is, in the electric load driving device of the present invention,
A current is caused to flow to the electric load by sequentially switching and operating each of the plurality of driving elements. For this reason, the power consumption of each driving element is significantly reduced as compared with the configuration in which the current flows through the electric load by only one driving element (the driving transistor 21 in FIG. 6) as in the conventional device. There is no need to attach a heat dissipating member such as a heat dissipating fin. As a result, it is possible to widen the selection range of the component layout in the apparatus and the outer material of the apparatus. In addition, the number of components that cannot be automatically mounted, such as heat dissipating members, can be reduced. Therefore, according to the electric load driving device of the present invention, the flexibility of the device design and the manufacturing efficiency can be improved.

In the case where the power supply control means intermittently supplies power to the electric load, the power supply control means includes:
The energization control means may be configured to sequentially switch the drive element to be operated among the plurality of drive elements each time the electric load is energized. Further, when the energization control means continuously energizes the electric load, the energization control means, during the energization period to the electric load,
What is necessary is just to comprise so that the drive element operated among the said several drive elements may be switched sequentially.

[0011] In the electric load drive device according to the third aspect, the energization control means may include:
When sequentially switching the driving elements to be operated among the plurality of driving elements, it is more certain to provide an overlap period in which the driving element already operated and the driving element to be operated next operate simultaneously. That is, according to the electric load driving device of the fourth aspect, a state occurs in which the driving element that is already operating and the driving element that is operated next are simultaneously operated for the predetermined overlap time, and the electric load is reduced. Can be reliably conducted.

[0012] On the other hand, in the electric load driving device according to the first to fourth aspects, various semiconductor elements such as a transistor and a thyristor can be considered as the driving element. The use of a transistor as an element is advantageous in that the transistor can be easily operated (turned on) and the device can be easily designed. As the transistor, a bipolar transistor or a MOS transistor can be used.

Next, a fuel injection valve driving apparatus according to a sixth aspect of the present invention for achieving the second object is provided with a plurality of fuel injection valves for injecting fuel into an internal combustion engine. A current is caused to flow simultaneously through a plurality of excitation coils provided and connected in parallel with each other, whereby the plurality of fuel injection valves are simultaneously opened to inject fuel into the internal combustion engine.

[0014] In the fuel injection valve driving device of the present invention, the exciting coil group consisting of the plurality of exciting coils connected in parallel is connected in series with each other and connected in parallel with each other. A plurality of drive elements that operate in accordance with a command from the controller to simultaneously supply current to the plurality of exciting coils, energizing time determining means for determining an energizing time of the exciting coils according to an operating state of the internal combustion engine, and a crank of the internal combustion engine. Each time the shaft rotates by a predetermined angle, a command is given to any one of the plurality of drive elements, and the drive elements are operated for the determined energization time, thereby simultaneously performing the energization to the plurality of excitation coils. Means are provided.

In particular, the injection control means is configured to sequentially switch the drive element to be operated this time among the plurality of drive elements each time the crankshaft of the internal combustion engine rotates by the predetermined angle. That is, in the fuel injection valve driving device according to the present invention, similarly to the above-described electric load driving device according to claims 1 to 5, a plurality of fuel elements are operated by sequentially switching each of the plurality of driving elements. The current is caused to flow simultaneously to the excitation coil of the injection valve.

For this reason, the power consumption of each drive element is significantly reduced as compared with the conventional apparatus in which the current flows through the exciting coil by only one drive element (the drive transistor 21 in FIG. 6). In addition, it is not necessary to attach a radiation member such as a radiation fin to the drive element. as a result,
As in the case of the electric load driving device according to the first to fifth aspects, flexibility in device design and manufacturing efficiency can be improved.

In the fuel injector driving apparatus of the present invention, the energizing time τ determined by the energizing time determining means is
If the time required for the crankshaft of the internal combustion engine to rotate by the predetermined angle is shorter than tC, the exciting current is intermittently applied to the plurality of excitation coils every time the crankshaft rotates by the predetermined angle. . If the energization time τ is longer than the time tC, the drive element that has already been operated and the drive element that is to be operated next overlap by the time of “τ−tC” and operate simultaneously. Is generated, and as a result, an exciting current is continuously supplied to the plurality of exciting coils.

According to a sixth aspect of the present invention, in the fuel injector drive device, when the energization time τ determined by the energization time determination means is equal to the time tC required for the crankshaft of the internal combustion engine to rotate by the predetermined angle. In this case, an exciting current should be supplied to the exciting coil of the fuel injection valve.

However, in this case, every time the crankshaft rotates by the predetermined angle, the operation of the drive element that is already operating and the start of the operation of the next drive element are simultaneously performed. Therefore, there is a possibility that the power supply to the exciting coil may be momentarily interrupted at the switching timing.

Therefore, in order to solve this problem, in the fuel injection valve driving device according to claim 7, the rotation time detecting means detects the time tC required for the crankshaft of the internal combustion engine to rotate by the predetermined angle. I do. Then, a value obtained by dividing the energization time τ determined by the energization time determination means by the time tC detected by the rotation time detection means (that is, the ratio of the energization time τ to the time tC required for the crankshaft to rotate by the predetermined angle). When (= τ / t C)) is equal to or greater than the predetermined value N, the resetting means resets the energization time τ to a time longer than the time t C detected by the rotation time detecting means.

According to the fuel injection valve driving apparatus of the seventh aspect, by setting the predetermined value N to 1, the energization time τ determined by the energization time determination means can be calculated as:
When the time required for the crankshaft of the internal combustion engine to rotate by the predetermined angle is equal to the time tC, the injection control means operates each drive element for the energization time reset to a time longer than the time tC. As a result, a state is provided in which the driving element that is already operating and the driving element that is operated next overlap and operate simultaneously, and continuous energization to a plurality of excitation coils can be reliably performed. Become like

The predetermined value N is desirably set to 1, but may be set to a value smaller than 1 and can be regarded as substantially 1, such as 0.9. That is, if the predetermined value N is set to, for example, 0.9, even when the ratio (τ / tC) is 0.9, the energizing coil is continuously energized and the fuel for the internal combustion engine is supplied. This is because the injection amount becomes relatively large, but usually, in this type of device, the energization time τ is set short thereafter by air-fuel ratio feedback control or the like, so that there is no major problem.

On the other hand, in the fuel injection valve driving device according to the sixth and seventh aspects, as the driving element, various semiconductor elements such as a transistor and a thyristor can be considered. The use of a transistor as an element is advantageous in that the transistor can be easily operated and the design of the device is easy. As the transistor, a bipolar transistor or a MOS transistor can be used.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. It is needless to say that the present invention is not limited to the embodiments described below, and can take various forms as long as it belongs to the technical scope of the present invention.

FIG. 1 shows an electronic control unit (hereinafter referred to as EC) of an embodiment for controlling a four-cylinder engine mounted on an automobile.
FIG. 2 is a configuration diagram illustrating a configuration of U (referred to as U). Note that the ECU 1 of the present embodiment controls fuel injection, ignition timing, and the like for the engine. Here, a description will be mainly given of a portion related to fuel injection control. Further, the ECU 1 of the present embodiment is configured to inject fuel by the above-described simultaneous injection method.

As shown in FIG. 1, in the present embodiment, each excitation coil L of four electromagnetic fuel injection valves (hereinafter referred to as injectors) provided for each cylinder of the engine is provided.
One ends of L1, L2, L3 and L4 are commonly connected to a battery voltage VB (normally 12 V) outside the ECU 1.

The ends of the two exciting coils L1 and L4 opposite to the battery voltage VB of the two exciting coils L1 and L2 are opposite to the battery voltage VB of the other two exciting coils L3 and L4. Are connected to the ECU 1 via two connector terminals J1 and J2, respectively.

Then, the two connector terminals J1, J
2 are connected to each other inside the ECU 1. Therefore, the ends of the four exciting coils L1 to L4 opposite to the battery voltage VB are commonly connected inside the ECU 1. Next, the ECU 1 controls the four excitation coils L1 to L1.
A plurality of NPN transistors (hereinafter simply referred to as transistors) Tr1, Tr2, Tr3 and Tr4 having collectors connected in common to a connection point P of the connector terminals J1 and J2 are provided as a plurality of drive elements which simultaneously supply current to L4. The emitters of the transistors Tr1 to Tr4 are commonly connected to a ground potential (0 V).

That is, in the ECU 1 of the present embodiment, the four transistors Tr1 to Tr4 connected in parallel to each other.
Are connected in series to an excitation coil group consisting of four excitation coils L1 to L4 also connected in parallel. Then, if any one of the four transistors Tr1 to Tr4 is turned on, an exciting current flows to the four exciting coils L1 to L4 at the same time through the turned on transistors, and as a result, all the injectors are simultaneously opened. Speak
Fuel is simultaneously injected into all cylinders of the engine.

Further, as shown in FIG. 1, the ECU 1 detects a pressure in the intake pipe (intake pipe pressure) of the engine 3 by outputting a pulse signal every time the crankshaft of the engine rotates by a predetermined angle. Signals from various sensors for controlling the engine, such as an intake pipe pressure sensor 5, a water temperature sensor 7 for detecting a cooling water temperature of the engine, and an air-fuel ratio sensor 9 for detecting an air-fuel ratio of the engine, are input, and these signals are input. An input circuit 11 for waveform shaping or digital conversion and output, and a fuel injection amount and an ignition timing (ignition timing) for the engine are calculated based on a signal from the input circuit 11, and an injector, an igniter, and the like are calculated based on the calculation result. Single-chip microcomputer (hereinafter referred to as CPU) 13 that outputs a drive signal for driving
And an output circuit 15 for turning on the transistors Tr1 to Tr4 in accordance with injector driving signals S1, S2, S3 and S4 output from the CPU 13.

The output circuit 15 turns on the transistor Tr1 by amplifying the drive signal S1 and supplying it as a base current to the base of the transistor Tr1 while the drive signal S1 from the CPU 13 is at the high level.
Further, while the drive signal S2 from the CPU 13 is at a high level, the drive signal S2 is amplified and supplied as a base current to the base of the transistor Tr2 to turn on the transistor Tr2. Similarly, while the drive signal S3 from the CPU 13 is at a high level, the output circuit 15 amplifies the drive signal S3 and supplies it as a base current to the base of the transistor Tr3, thereby turning on the transistor Tr3. While the drive signal S4 from the CPU 13 is at the high level, the transistor Tr4 is turned on by amplifying the drive signal S4 and supplying it as a base current to the base of the transistor Tr4.

The ECU 1 also has the connector terminal J
1, a resistor 17 having one end connected to a connection point P of J2;
One end is connected to the ground potential (0 V), and the other end is connected to a resistor 17.
Of the capacitor 1 connected to the end opposite to the connection point P
9, a flyback voltage absorbing circuit is provided.

Next, the processing executed by the CPU 13 to control the fuel injection to the engine will be described with reference to the flowcharts shown in FIGS. First, FIG. 2 is a flowchart illustrating an injection amount control process for determining a fuel injection amount.

The CPU 13 starts operating when an ignition switch (not shown) of the vehicle is turned on and power is supplied to the ECU 1. And the CPU 13
Executes an initialization process (not shown) for initializing the internal RAM, registers, and the like immediately after the operation is started,
Thereafter, the injection amount control process of FIG. 2 is repeatedly executed at predetermined time intervals. The CPU 13 executes a detection process (not shown) in parallel with the injection amount control process in FIG.
Based on a signal from the input circuit 11, an actual operating state of the engine such as an engine speed, an intake pipe pressure, a cooling water temperature, and an air-fuel ratio is detected.

As shown in FIG. 2, when the CPU 13 starts execution of the injection amount control process, first, in step (hereinafter simply referred to as "S") 100, the latest engine detected by execution of the above detection process is executed. Reads rotation speed, intake pipe pressure, cooling water temperature, air-fuel ratio, etc.

Then, in the subsequent S110, the above S100
Based on the engine speed and intake pipe pressure read in
A basic injection pulse width TP, which is a basic energization time (an energization time before correction) of the excitation coils L1 to L4, is calculated. Next, S
At 120, a water temperature correction coefficient K1 for correcting the basic injection pulse width TP according to the cooling water temperature is calculated based on the engine cooling water temperature read at S100. Then, in S130, based on the air-fuel ratio of the engine read in S100, an air-fuel ratio correction coefficient K2 for correcting the basic injection pulse width TP according to the air-fuel ratio is calculated.
Further, in subsequent S140, another correction coefficient K3 is calculated.

Then, in the next S150, the above S110
The basic injection pulse width TP calculated in the above is added to the above S120-S
By multiplying each of the correction coefficients K1, K2, and K3 calculated by each of the 140, the injection pulse width τ (= the final energization time (corrected energization time) of the exciting coils L1 to L4) is obtained.
TP × K1 × K2 × K3), and then the injection amount control process is temporarily terminated. Note that the injection pulse width τ is the valve opening time of the injector and corresponds to the fuel injection time.

Next, FIG. 3 is a flowchart showing a drive signal output process for outputting the injector drive signals S1 to S4 to the output circuit 15. The drive signal output process is started each time the crankshaft of the engine rotates 180 ° (every 180 ° CA) and at each ignition timing of each cylinder. Further, the four-cylinder engine of the present embodiment is a general one, and as shown in the uppermost row of FIGS. 4 and 5, every 180 ° CA and in the first cylinder # 1
→ 3rd cylinder # 3 → 4th cylinder # 4 → 2nd cylinder # 2
Ignition takes place.

As shown in FIG. 3, when the CPU 13 starts the execution of the drive signal output processing, first, in S200, the 360 ° CA time tC (that is, the 360 ° CA time t C) is obtained from the latest engine speed detected by the execution of the above-described detection processing. , The time required for the crankshaft of the engine to rotate 360 °, ie, the time required for one rotation of the engine).

Next, in S210, the value of a counter n for specifying the transistor to be turned on this time among the four transistors Tr1 to Tr4 is incremented by one.
In subsequent S220, the counter n after the increment is performed.
Is determined to be 8 or more. If the value of the counter n is not 8 or more, the process proceeds to S240 as it is. If the value of the counter n is 8 or more, the value of the counter n is returned to 0 in S230, and then the process proceeds to S240.

The value of the counter n is initialized to 7 by the above-described initialization processing. Therefore, CPU1
When the drive signal output process is started for the first time and the drive signal output process is executed for the first time, the value of the counter n is set to 0 by the processes of S210 to S230.

Here, in S240, the injection pulse width τ calculated on the basis of the operating state of the engine in S150 of the injection amount control processing (FIG. 2) is 360 ° calculated in S200.
The value divided by the CA time tC (that is, the 360 ° CA time t)
The ratio of the injection pulse width τ to C (= τ / tC) is
It is determined whether or not the value is equal to or more than a predetermined value N (1 in this embodiment). If the ratio (τ / tC) is not equal to or more than 1, the process directly proceeds to S260, but the ratio (τ / tC)
If C) is 1 or more, in S250, the injection pulse width τ
Is obtained by multiplying the 360 ° CA time tC by 1.1 (= 1.1
× tC), and then proceeds to S260.

In S260, it is determined whether or not the value of the counter n is 0. If not, in S270, whether or not the value of the counter n is 2 is determined. Then, if the value of the counter n is not 2, it is determined whether or not the value of the counter n is 4 in subsequent S280.
In subsequent S290, it is determined whether or not the value of the counter n is 6.

If it is determined in step S290 that the value of the counter n is not 6, that is, if the value of the counter n is not 0, 2, 4, or 6, the output of the drive signal is not changed. The process ends once. On the other hand, if a positive determination is made in any of the above S260 to S290, that is, if the value of the counter n is one of 0, 2, 4, and 6, the process proceeds to S300.

In step S300, the drive signals S1 to S4 are sent to the output circuit 15 so that the transistor corresponding to the value of the counter n among the four transistors Tr1 to Tr4 is turned on for the duration of the ejection pulse width τ. Is output at a high level. Specifically, when the value of the counter n is 0, the driving signal S1 is output at a high level for the duration of the ejection pulse width τ to turn on the transistor Tr1, and when the value of the counter n is 2, The drive signal S2 is output at a high level for the duration of the ejection pulse width τ to turn on the transistor Tr2. When the value of the counter n is 4, the drive signal S3 is output at a high level for the duration of the ejection pulse width τ to turn on the transistor Tr3. When the value of the counter n is 6, the drive signal S4 is output. Is output at a high level only for the duration of the injection pulse width τ, and the transistor T
Turn on r4.

However, in this S300, the drive signals S1 to S1
Only the process of changing any one of S4 from low level to high level is performed, and the drive signals S1 to
The process of returning S4 to the low level after the elapse of the injection pulse width τ is performed by another timer process.

After the process of S300 is completed, the drive signal output process is temporarily terminated. Next, the operation of the drive signal output process (FIG. 3) will be described with reference to FIGS. FIG. 4 shows the injection pulse width τ
FIG. 5 is a time chart showing the operation at the time of energization of less than 100% shorter than 360 ° CA time tC, and FIG. 5 is a time chart showing the operation at 100% energization where the injection pulse width τ is longer than 360 ° CA time tC. It is. 4 and FIG. 5 show that the drive signal output processing of FIG. 3 is performed in the first state after the CPU 13 starts the operation in response to the turning on of the ignition switch.
The operation when the counter n is set to 0 by the processing of S210 to S230 in FIG. 3 at the time of the first execution at the ignition timing of the cylinder # 1, that is, at the first ignition timing of the first cylinder # 1 Is shown.

First, in the drive signal output processing, the temperature is set to 180 ° C.
A, and for each ignition timing of each cylinder, a counter n
Is incremented (S210), and when the value of the counter n after the increment reaches 8, the value is reset to 0 (S220: YES,
S230).

Therefore, for example, if the value of the counter n is set to 0 at the first cylinder # 1 ignition timing shown on the leftmost side in FIGS.
Becomes 1 at the next ignition timing of the third cylinder # 3, becomes 2 at the next ignition timing of the fourth cylinder # 4, and becomes 3 at the next ignition timing of the second cylinder # 2. In this case, each time the ignition timing of the first cylinder # 1 arrives twice, that is, every time four times the 360 ° CA time tC (= 4 × tC), between 0 and 7. It will change repeatedly.

In the drive signal output processing, when the value of the counter n becomes 0, 2, 4, or 6 (S2
60 to S290: YES), four transistors Tr1
Of the drive signals S1 to S4, one of the drive signals S1 to S4 is output to the output circuit 15 at a high level so that the transistor corresponding to the value of the counter n among the transistors Tr4 to Tr4 is turned on for the duration of the ejection pulse width τ. S300).

In the drive signal output process, the value (τ / tC) obtained by dividing the injection pulse width τ calculated based on the operating state of the engine in S150 of the injection amount control process (FIG. 2) by the 360 ° CA time tC. Is not one or more (S24
0: NO), the injection pulse width τ calculated in S150 is used as it is, and conversely, if the above value (τ / tC) is 1 or more (S240: YES), the injection pulse width τ is set to 3
Value obtained by multiplying 60 ° CA time tC by 1.1 (1.1 × tC)
To be used again (S250).

Therefore, the injection pulse width τ calculated in S150 of the injection amount control process is shorter than the 360 ° CA time tC, and the value (τ / tC) obtained by dividing the injection pulse width τ by the 360 ° CA time tC is: If it is not equal to or greater than 1, the counter n is set at the ignition timing of the first cylinder # 1 shown on the leftmost side of FIG.
Are set to 0, the CPU 13 outputs drive signals S1 to S4 to the output circuit 15 as shown in FIG.

That is, as shown in FIG. 4, first, a high-level drive signal S1 is output to the output circuit 15 for the time of the injection pulse width τ from the ignition timing of the leftmost first cylinder # 1. Then, the transistor Tr1 is turned on for the duration of the ejection pulse width τ, and the output voltage VO, which is the voltage at the connection point P between the connector terminals J1 and J2, becomes
r1 drops to the collector-emitter saturation voltage VCE (typically about 0.3 V), so that all the exciting coils L
An exciting current flows through 1 to L4 via the transistor Tr1, and all injectors are simultaneously opened to inject fuel into all cylinders of the engine at the same time.

Thereafter, when the 360 ° CA time tC has elapsed and the ignition timing of the fourth cylinder # 4 has come, in this case, the value of the counter n becomes 2, and the injection pulse width from this point onward The high-level drive signal S2 is output to the output circuit 15 for the time τ. Then, the transistor Tr2 is turned on for the duration of the ejection pulse width τ, and the exciting current flows through all the exciting coils L1 to L4 via the transistor Tr2, as in the case where the transistor Tr1 is turned on. Will open at the same time.

Further, after that, when the 360 ° CA time tC has elapsed and the ignition timing of the first cylinder # 1 has come, in this case, the value of the counter n becomes 4, so that the injection pulse The high-level drive signal S3 is output to the output circuit 15 for the time of the width τ. Then, the transistor Tr3 is turned on for the duration of the ejection pulse width τ,
An exciting current flows through all the exciting coils L1 to L4 via the transistor Tr3, whereby all the injectors are simultaneously opened.

Further, after that, the 360 ° CA time tC
Has elapsed and the ignition timing of the fourth cylinder # 4 has been reached,
In this case, since the value of the counter n becomes 6, the high-level drive signal S4 is output to the output circuit 15 for the duration of the ejection pulse width τ from that time. Then, the transistor Tr4 is turned on for the duration of the ejection pulse width τ, and an exciting current flows through all the exciting coils L1 to L4 via the transistor Tr4, whereby all the injectors are simultaneously opened.

Next, when the ignition timing of the first cylinder # 1 comes, in this case, the value of the counter n is returned to 0, and thereafter, the above-described operation is repeated. In this way, the injection pulse width τ calculated based on the operating state of the engine is shorter than the 360 ° CA time tC, and the value (τ / τ) obtained by dividing the injection pulse width τ by the 360 ° CA time tC.
If tC) is not 1 or more, the driving signal output
For each 360 ° CA executed four times, four transistors T
Any one of r1 to Tr4 is turned on for the duration of the injection pulse width τ, and the intermittent simultaneous energization to all the excitation coils L1 to L4 is performed. Each time the energization is performed, one of the four transistors Tr1 to Tr4 is turned on. The transistors that are turned on this time are sequentially switched.

On the other hand, when the value (τ / tC) obtained by dividing the injection pulse width τ calculated in S150 of the injection amount control process by the 360 ° CA time tC is 1 or more, the leftmost position in FIG. Counter n at the ignition timing of the first cylinder # 1 shown in FIG.
Are set to 0, the CPU 13 outputs drive signals S1 to S4 to the output circuit 15 as shown in FIG.

That is, basically, similarly to the operation shown in FIG. 4, every 360 ° CA at which the drive signal output process is executed twice, the four transistors Tr1 to Tr4 are sequentially switched so that the ejection pulse width τ However, in this case, the injection pulse width τ is 1.1 times the 360 ° CA time tC (1.1.
1 × tC), as shown in FIG. 5, as shown in FIG. 5, the time between the already-turned-on transistor and the next-turned-on transistor is t0 (= 0) corresponding to 10% of the 360 ° CA time tC. .1 × t C), resulting in a state where they are simultaneously turned on.

Therefore, in this case, the connector terminal J1
, J2, the output voltage VO remains at the collector-emitter saturation voltage VCE (about 0.3 V) of the transistors Tr1 to Tr4, and continues to the four exciting coils L1 to L4. As a result, an exciting current flows.

In the ECU 1 of this embodiment, the drive signal output processing of FIG. 3 corresponds to the power supply control means. Also,
3 is output from the CPU 13 by the execution of the drive signal output process of FIG.
Drive signals S1 to S4 supplied to the bases of r1 to Tr4
Corresponds to a command for operating the transistors Tr1 to Tr4 as driving elements. On the other hand, in the ECU 1 of the present embodiment, the injection amount control process (S100 to S100) of FIG.
150) corresponds to the energization time determination means, and corresponds to S210 in FIG.
To S230, S260 to S300, and the above-described timer processing correspond to the injection control means. Then, S in FIG.
200 corresponds to the rotation time detecting means, and S240 and S250 in FIG. 3 correspond to the resetting means.

As described in detail above, the ECU of this embodiment
1, four transistors Tr connected in parallel with each other
1 to Tr4 are connected in series to an excitation coil group consisting of four excitation coils L1 to L4, and by turning on one of the four transistors Tr1 to Tr4,
An exciting current is supplied to the exciting coils L1 to L4, and the transistors to be turned on among the four transistors Tr1 to Tr4 are sequentially switched.

More specifically, when the excitation coils L1 to L4 are intermittently energized as shown in FIG. 4, the transistors to be turned on among the four transistors Tr1 to Tr4 are sequentially switched every time the energization is performed. When the energizing coils L1 to L5 are continuously energized as shown in FIG. 5, the four transistors Tr1 to T5 are operated during the energizing period.
The transistors to be turned on in r4 are sequentially switched.

Therefore, as in the conventional device shown in FIG.
Compared to a configuration in which a current flows through the exciting coil by only one driving transistor 21, the transistor Tr1
The power consumption of the transistors Tr1 to Tr4 is remarkably reduced, so that it is not necessary to attach a heat radiation member such as a radiation fin to the transistors Tr1 to Tr4.

First, a junction temperature Tj [° C.] of a transistor is generally obtained by the following equation (1), and its maximum rating is 150 [° C.].
It is. In the equation (1), IC is a current flowing through the transistor (collector-emitter current) [A], VCE is a collector-emitter saturation voltage [V] of the transistor, and Rth is a transistor's current. Thermal resistance [° C./W], D is the drive duty ratio of the transistor, and Ta is the ambient temperature of the transistor [° C.].

[0066]

Tj = IC × VCE × Rth × D + Ta −1 Equation (1) Here, the exciting coil L is formed by only one transistor.
When current is continuously supplied to 1 to L4 as shown in FIG. 5, the drive duty ratio D of the transistor is 1 (= 100%).
Therefore, in equation (1), IC = 6 [A], VCE
= 0.3 [V], Rth = 63 [° C./W], Ta = 80
If the temperature is [° C.], the junction temperature Tj of the transistor is about 192 [° C.], which exceeds the maximum rating of 150 [° C.]. Therefore, in this case, a heat radiation member such as a heat radiation fin is attached to the transistor, and the junction temperature T
It is necessary to keep j below the maximum rating.

On the other hand, in the ECU 1 of the present embodiment, even when the excitation coils L1 to L4 are continuously energized, the drive duty ratio D of each of the four transistors Tr1 to Tr4 is as shown in FIG. About 1/4 (= 2
5%), the junction temperature Tj of each of the transistors Tr1 to Tr4 is about 107 ° C. under the same conditions as above.
It becomes below the maximum rating without attaching a heat radiation member.

As described above, according to the ECU 1 of the present embodiment, there is no need to attach a radiation member such as a radiation fin to the transistors Tr1 to Tr4.
It is possible to widen the selection range of the component layout in the inside and the outer material of the ECU 1 (the material of the printed circuit board and the case) and to reduce the number of components that cannot be automatically mounted. Therefore, flexibility in device design and manufacturing efficiency can be improved. In addition, E of the present embodiment
In the CU1, as shown in FIG. 5, four exciting coils L1.
In the case where the exciting current is continuously supplied to L4, the overlap time t0 (=) in which the already-turned-on transistor and the next-turned-on transistor overlap and are simultaneously turned on.
0.1.times.tC), the continuous energization of the exciting coils L1 to L4 can be reliably performed.

Incidentally, in the ECU 1 of the present embodiment, S200, S240,
Even if S250 and S250 are deleted, the same effects as those described above can be obtained. That is, S2 of the drive signal output process
Even if 00, S240, and S250 are deleted, every 360 ° CA at which the drive signal output process is executed twice, one of the four transistors Tr1 to Tr4 determines whether or not S150 of the injection amount control process (FIG. 2). Are sequentially switched and turned on only for the time of the injection pulse width τ calculated in. Therefore, the injection pulse width τ calculated in S150 is 360 ° CA
If the time is shorter than the time tC, similar to the operation shown in FIG.
Intermittent energization to all the excitation coils L1 to L4 is performed, and the injection pulse width τ calculated in S150 is 360
If the CA time is longer than the time tC, the transistor that has already been turned on and the transistor that will be turned on next become “τ−tC
Is turned on at the same time for the time of "", and continuous energization to all the exciting coils L1 to K4 is performed similarly to the operation shown in FIG.

However, if S200, S240, and S250 of the drive signal output processing are performed as in the ECU 1 of the present embodiment, the following points are advantageous. That is, when S200, S240, and S250 in the drive signal output process are deleted and the injection pulse width τ calculated in S150 in the injection amount control process is equal to the 360 ° CA time tC, the excitation coil L1 is originally used. ~ L4, the exciting current should be passed continuously. In this case, 360 °
Since the transistor that is already on is turned off and the next transistor is turned on at the same time for each CA, the excitation coil L1
To L4 may be momentarily interrupted.

On the other hand, if the steps S200, S240, and S250 are performed as in the ECU 1 of the present embodiment, the injection pulse width τ calculated in step S150 of the injection amount control processing is reduced by 360 ° CA time. The value divided by tC (τ /
When tc) is 1 or more, the injection pulse width τ is 360
Is reset to a value (1.1 × tC) obtained by multiplying the CA time tC by 1.1 (1.1 × tC). Therefore, when the injection pulse width τ calculated in S150 is equal to the 360 ° CA time tC, it is already turned on. Time t0 when the transistor that is turned on and the transistor that is turned on next overlap and turn on at the same time
(= 0.1.times.tC) is assuredly provided. As a result, continuous energization to the exciting coils L1 to L4 can be reliably performed.

In the present embodiment, the predetermined value N determined in S240 of the drive signal output process is set to 1, but the predetermined value N is set to a value smaller than 1 and can be regarded as substantially 1. May be set. That is, if the predetermined value N is set to, for example, 0.9, the injection pulse width τ calculated in S150 is divided by the 360 ° CA time tC (τ / tC).
) Is 0.9, the energizing coils L1 to L4 are continuously energized, and the fuel injection amount to the engine becomes large. However, in the ECU 1 of this embodiment and this type of device, Since the injection pulse width τ is corrected according to the air-fuel ratio of the engine or the like, if the fuel injection amount becomes excessive, the injection pulse width τ will be set to a short time soon.
This is because it does not become a major obstacle.

On the other hand, the ECU 1 of the above-described embodiment injects fuel by the simultaneous injection method (simultaneous injection method). However, the present invention collects cylinders having adjacent suction strokes into groups, and performs two engine rotations. The same applies to a so-called group injection method in which fuel injection is performed independently for each group in synchronization with the suction stroke of each group.

Further, in the ECU 1 of the above-described embodiment, a driving element for supplying a current to the exciting coils L1 to L4 is
Although an NPN transistor was used, the driving element was P
NP transistor, N-channel or P-channel M
An OS transistor may be used, or another semiconductor element such as a thyristor that can be turned on / off in response to an external command may be used instead of such a transistor. However, using a transistor as a driving element is advantageous in that it can be easily operated (turned on).

On the other hand, the ECU 1 of the above embodiment uses the exciting coils L1 to L4 of the injectors as electric loads, but the electric load driving device of the present invention is not limited to the exciting coils L1 to L4 of the injectors. The present invention can be similarly applied to a device that supplies electricity to another electric load, such as an electric motor or a lamp.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a configuration of an electronic control unit (ECU) according to an embodiment.

FIG. 2 is a flowchart illustrating an injection amount control process executed by the electronic control device of the embodiment.

FIG. 3 is a flowchart illustrating a drive signal output process executed by the electronic control device of the embodiment.

FIG. 4 is a time chart showing an operation when current is supplied to the exciting coil at less than 100%.

FIG. 5 is a time chart showing an operation at the time of 100% energization of an exciting coil.

FIG. 6 is an explanatory diagram illustrating a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electronic control device (ECU) 3 ... Rotation sensor 5
... intake pipe pressure sensor 7 ... water temperature sensor 9 ... air-fuel ratio sensor 11 ... input circuit 13 ... single chip microcomputer (CPU)
15 Output circuit L1 to L4 Excitation coil Tr1 to Tr4 Transistor

Claims (8)

[Claims] 1. A plurality of drive elements connected in series to an electric load and connected in parallel with each other, each of which operates according to an external command to flow a current to the electric load; An electric load driving device, comprising: an energization control unit that energizes the electric load by giving the command to any one of the driving elements to operate the driving element. An electric load driving device, characterized by being configured to sequentially switch the driving element to be operated among the plurality of driving elements. 2. The electric load driving device according to claim 1, wherein the energization control means intermittently energizes the electric load and each time energizing the electric load, An electric load driving device characterized by being configured to sequentially switch driving elements to be operated among driving elements. 3. The electric load driving device according to claim 1, wherein the energization control unit continuously energizes the electric load and, during the energization period, among the plurality of driving elements. An electric load driving device, wherein the driving elements to be operated are sequentially switched. 4. The electric load driving device according to claim 3, wherein the energization control unit is configured to sequentially switch a driving element to be operated among the plurality of driving elements, and An electric load driving device is configured to provide an overlapping period in which the driving element to be operated at the same time operates. 5. The electric load driving device according to claim 1, wherein the driving element is a transistor. 6. A plurality of fuel injection valves for injecting fuel into an internal combustion engine, each of which is provided with a plurality of fuel injection valves which are connected in parallel with each other, and which simultaneously supply current to a plurality of excitation coils, thereby simultaneously opening the plurality of fuel injection valves. A fuel injection valve driving device, which is connected in series to an excitation coil group including a plurality of excitation coils connected in parallel and connected to each other in parallel, and operates in accordance with an external command. A plurality of drive elements that simultaneously supply current to the plurality of excitation coils; an energization time determination unit that determines an energization time of the excitation coil according to an operation state of the internal combustion engine; Each time the motor rotates by an angle, the command is given to any one of the plurality of drive elements to operate the drive elements for the determined energizing time, whereby the plurality of excitation coils Injection control means for performing simultaneous energization, and the injection control means is configured to sequentially switch a drive element to be operated this time among the plurality of drive elements each time the crankshaft rotates by the predetermined angle. A fuel injector drive. 7. The fuel injection valve driving device according to claim 6, wherein a rotation time detecting means for detecting a time required for the crankshaft to rotate by the predetermined angle, and an energization determined by the energization time determining means. Resetting means for resetting the energization time to a time longer than the time detected by the rotation time detecting means, when a value obtained by dividing the time by the time detected by the rotation time detecting means is equal to or more than a predetermined value; A fuel injection valve driving device, comprising: 8. The fuel injection valve driving device according to claim 6, wherein the driving element is a transistor.