JP3769792B2 - Capacitor device used for in-vehicle electronic control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a capacitor device for a fuel injection control for use in a fuel injection control system of a vehicle-mounted diesel engine, suitably employed in the system to be particularly used in combination of two capacitors between a pilot injection and a main injection vehicle The present invention relates to the implementation of a capacitor device structure used in an electronic control device .
[0002]
[Prior art]
As is well known in the fuel injection control system of a vehicle-mounted diesel engine, a voltage higher than the output voltage of the vehicle-mounted battery is stored in advance in a capacitor in order to inject ultra-high pressure fuel from an injector that is a fuel injection valve. I have to. Then, when the injector is driven, that is, when energization of the solenoid valve is started, the voltage stored in the capacitor is discharged at once, thereby obtaining a stable valve opening response of the injector.
[0003]
In recent years, in such on-vehicle diesel engines, so-called pilot injection, in which a minute amount of fuel is injected just before the main injection in each cylinder, has been attempted to improve fuel consumption, reduce exhaust gas, and reduce noise. A fuel injection control system has also been proposed and put into practical use. In this case, the two capacitors for pilot injection and main injection are used together as the fuel injection control capacitor.
[0004]
FIG. 3 and FIG. 4 show the configuration of an electronic control device that is generally employed as a fuel injection control system for realizing such pilot injection in a vehicle-mounted diesel engine, and a driver built in the control device.
[0005]
First, as shown in FIG. 3, the electronic control unit calculates the fuel injection amount, the injection timing, and the like based on the buffers 1 and 2 for capturing signals input through various sensors and switches, and the captured signals. The microcomputer 3 includes a driver 4 that drives an actuator based on the calculated contents, that is, an injector in this case, and a power supply circuit 5 that supplies power to the microcomputer 3 and the driver 4 based on the battery voltage. It has a configuration that can be.
[0006]
In addition, although illustration is omitted here, as the sensors and switches,
A sensor for detecting the rotational speed of the engine or fuel injection pump.
・ Sensor for cylinder discrimination of the engine.
・ Sensor for detecting intake pressure of the engine.
・ A sensor for detecting the intake air temperature of the engine.
・ Sensor for detecting the coolant temperature of the engine.
A sensor for detecting the accelerator operation amount of the vehicle.
-Switches that indicate whether the engine has been started and various operating conditions.
And so on.
[0007]
Further, as shown in FIG. 3, the microcomputer 3 includes a CPU (Central Processing Unit), a ROM mainly used as a program memory, a RAM used as a data memory, and an analog signal digitally. It is built with an A / D converter for conversion. Basically,
(1) While taking in the detection signals from the various sensors and the state of the switch into the RAM directly or via the A / D converter, according to the control program stored in the ROM, the fuel injection amount, the injection timing, etc. Is calculated.
(2) A signal for controlling the driving of the actuator (injector) is output to the driver 4 according to the calculation result.
The process is executed.
[0008]
On the other hand, the driver 4 that drives the injector under the control of the microcomputer 3 has the configuration shown in FIG.
Hereinafter, the configuration as the driver 4 and the function of each unit will be sequentially described with reference to FIG.
[0009]
As shown in FIG. 4, the driver 4 is provided with two capacitors, a charge capacitor 41 for pilot injection and a charge capacitor 42 for main injection, and these capacitors 41 and 42 are charged. The electric charge is discharged through the injector driving electromagnetic valve 6 based on the control signal from the microcomputer 3. The control signal applied from the microcomputer 3 to the driver 4 is as follows:
-For example, a charge pulse CP alternating at a frequency of 25 KHz,
-Solenoid valve energization pulse DP having a timing and pulse width corresponding to pilot injection and main injection,
A control signal PS for controlling the separation circuit 47 for the pilot injection charge capacitor 41, and a control signal MS for controlling the separation circuit 48 for the main injection charge capacitor 42,
There is. The application mode of these control signals is as shown in FIG.
[0010]
In the driver 4, the gate circuit 43 is a circuit that applies the charge pulse CP to the charge circuit 44 on condition that the solenoid valve energization pulse DP is not applied. This is a circuit for charging the charge capacitors 41 and 42 for pilot injection and main injection based on a charge pulse CP.
[0011]
Incidentally, in the charge circuit 44, the primary side transistor 443 of the charge transformer 445 is turned on / off in synchronization with the on / off of the transistor 441 based on the charge pulse CP. From the next side, the DC voltage rectified by the diodes 446a and 446b is output as the charging voltage for the capacitors 41 and 42. Note that the circuit 444 is a protection circuit of the transistor 443.
[0012]
In the charge circuit 44, voltage dividing circuits 447 and 448 connected to the charge capacitors 41 and 42 for pilot injection and main injection, respectively, are for detecting the charge voltage by the capacitors 41 and 42. Circuit. The divided outputs of the circuits 447 and 448, that is, the charge voltages by the capacitors 41 and 42 are compared with the determination voltages in the comparators 451 and 452 of the charge completion determination circuit 45, respectively. Then, when both of the charge voltages of the capacitors 41 and 42 reach the determination voltage (for example, 110 V) indicating the completion of the charge, this is applied from the AND gate 453 of the charge completion determination circuit 45 to the transistor 442 of the charge circuit 44. The logic H level signal to be turned on is applied, and the above-described charging operation by the charging circuit 44 is prohibited.
[0013]
In the driver 4, the energization control circuit 46 is a circuit for controlling energization to the electromagnetic valve 6 based on the electromagnetic valve energization pulse DP applied from the microcomputer 3, and the disconnection circuits 47 and 48 are the same as the microcomputer. 3 is a circuit for controlling the separation timing of the charge capacitors 41 and 42 for pilot injection and main injection from the solenoid valve 6 based on the control signals PS and MS applied from 3.
[0014]
The constant current circuit 49 is also a circuit for supplying a constant current to the electromagnetic valve 6 while the pulse DP is applied based on the electromagnetic valve energization pulse DP applied from the microcomputer 3.
[0015]
FIG. 5 shows a driving mode of the injector driving solenoid valve 6 by such a driver 4. Next, referring to FIG. 5 together, the fuel injection control mode including pilot injection by the system will be further described. To do.
[0016]
In the driver 4, on the basis of the charge pulse CP shown in FIG. 5 (a), the charge capacitors 41 for pilot injection and main injection are used in the manner shown in FIGS. 5 (c) and 5 (d). 42 is charged.
[0017]
Now, assuming that these charge voltages have reached the determination voltage set in the charge completion determination circuit 45, the charge completion determination circuit 45 starts from the transistor of the charge circuit 44 in the manner shown in FIG. A charge completion determination signal is output to 442. While the charge completion determination signal is being output, the charge circuit 44 is prohibited from charging.
[0018]
After that, the solenoid valve energization pulse DP is applied in the manner shown in FIG. 5 (g), and the control signals PS and MS are applied in the manner shown in FIGS. 5 (e) and (f). By
(1) First, the electric charge charged in the charge capacitor 41 for pilot injection is discharged at once through the electromagnetic valve 6 and is indicated as “P” in the time region corresponding to the control signal PS in FIG. For example, a large current of about 8 A (amperes) flows through the electromagnetic valve 6. Thereby, the valve opening responsiveness as an injector is also ensured suitably. Further, after the capacitor 41 is discharged, as indicated by “H” in the same time region corresponding to the control signal PS in FIG. 5H, for example, about 3 A required for holding the valve open of the injector. Constant current is supplied through the constant current circuit 49.
(2) Next, the electric charge charged in the charge capacitor 42 for main injection is discharged at once through the electromagnetic valve 6 and is indicated as “P” in the time region corresponding to the control signal MS in FIG. For example, a large current of about 8 A flows through the electromagnetic valve 6. Thereby, the valve opening responsiveness as an injector is also ensured suitably. Further, after the capacitor 42 is discharged, as indicated by “H” in the same time region corresponding to the control signal MS in FIG. A constant current of about 3 A is supplied through the constant current circuit 49.
In this manner, the injector control for the pilot injection and the main injection, that is, the fuel injection control is realized.
[0019]
In this case, it takes about 3 ms (milliseconds) for each of the charge capacitors 41 and 42 for pilot injection and main injection to be charged to a predetermined voltage such as 110V. The time from the end of pilot injection to the start of main injection is as short as about 1 ms.
[0020]
For this reason, in such a fuel injection control system, it is indispensable to separately provide the two charge capacitors 41 and 42 for pilot injection and main injection.
[0021]
[Problems to be solved by the invention]
In each of the charge capacitors 41 and 42 for pilot injection and main injection, the high voltage of about 110V is repeatedly charged and discharged when the fuel injection control is repeatedly executed.
[0022]
For this reason, the capacitors 41 and 42 are required to have a relatively high withstand voltage and excellent frequency characteristics and temperature characteristics. As a capacitor that can satisfy such conditions, there is a film capacitor.
[0023]
On the other hand, the capacitance required for these capacitors 41 and 42 is obtained as follows.
That is, in order to obtain the peak current of about 8A at the start of energization of the solenoid valve 6 through the discharge of the charges charged in the capacitors 41 and 42, the charge energy thereof is, for example, about 60 mJ (millijoule). Energy is required. At this time, if the voltage is increased to about 110 V as described above,
E = (1/2) CV ^ 2 ("^" represents power)
60 = (1/2) C × 110 ^ 2
From this, it can be seen that a capacitance of 10 μF is required as the capacitance C.
[0024]
As described above, as the charge capacitors 41 and 42 for the pilot injection and the main injection, a large-capacity film capacitor having a withstand voltage of 110 V or more and a capacitance of 10 μF is usually used.
[0025]
FIG. 6 shows a general structure of a capacitor device in which a film capacitor satisfying such specifications is mounted as the charge capacitor 41 or 42, and a mounting mode of the device on a printed board.
[0026]
6A is a front view when the capacitor device is mounted on the printed circuit board PWB, and FIG. 6B is a side view of the capacitor device. FIG. FIG. 3 is a bottom view showing a bottom structure of the capacitor device.
[0027]
As shown in FIGS. 6 (a) to 6 (c), such a capacitor device is usually appropriate in a state where the capacitor (film capacitor) 41 or 42 is inserted into a package PK made of resin or metal. The structure is sealed and fixed with a filler.
[0028]
Due to the above-described capacity of the capacitor (film capacitor) 41 or 42, the size of the package PK is also a considerably large size of about 16 mm long × 44 mm wide × 28 mm high.
[0029]
Further, from the capacitor (film capacitor) 41 or 42, lead wires Ra and Rb for wiring made of steel wires are usually drawn out. When mounting the capacitor device on the printed circuit board PWB, FIG. ) And (b), these leads Ra and Rb are fixed to the wiring pattern of the printed circuit board PWB by solder HP.
[0030]
However, when such capacitor devices are used as the charge capacitors 41 and 42 for pilot injection and main injection that are employed in the fuel injection control system of the above-described on-vehicle diesel engine,
(A) In general, an electronic component used in an on-vehicle electronic control device is required to withstand a vibration frequency of, for example, 11.7 Hz to 100 Hz and an acceleration of 4.4 G as its vibration resistance specification. According to the above-described package size of the capacitor device, it is difficult to satisfy such vibration resistance specifications unless some reinforcement is applied.
(B) In the capacitor device, as described above, the two leads Ra and Rb of the capacitor 41 or 42 are mounted on the printed circuit board PWB by being soldered to the wiring pattern of the printed circuit board PWB. Since the capacitor 41 or 42 itself is large in size, the arrangement pitch of the leads Ra and Rb naturally increases. For this reason, when exposed to a large change in ambient temperature such as a cooling / heating cycle, the stress caused by the difference in thermal expansion coefficient between the printed circuit board PWB and the capacitor device body is applied to the soldered portion. It will be added intensively and the solder HP will be easily cracked. When the crack is generated in the solder HP, the capacitor 41 or 42 is also electrically opened, and the valve opening response described above cannot be obtained when the injector is driven.
And so on.
[0031]
The present invention has been made in view of such circumstances, and as an apparatus on which the charge capacitors for pilot injection and main injection are mounted, an electronic component used for an on-vehicle electronic control apparatus without any reinforcement or the like An object of the present invention is to provide a capacitor device used in an on-vehicle electronic control device that can satisfy the vibration resistance specification.
[0032]
In addition, the present invention is a device on which the charge capacitors for the pilot injection and the main injection are mounted, and the electric reliability can be suitably maintained even with respect to environmental changes such as a thermal cycle . An object of the present invention is to provide a capacitor device used in an electronic control device .
[0033]
[Means for Solving the Problems]
In order to achieve these objects, the present invention focuses on the fact that two capacitors for pilot injection and main injection are essential in the fuel injection control system having the pilot injection function described above. As a structure,
A pilot-injection capacitor (first capacitor) and a main-injection capacitor (second capacitor) are arranged in parallel to face each other, and four leads drawn from the first and second capacitors It is hermetically fixed in one package so as to form a square shape, and is soldered and fixed to the printed circuit board by the four leads of the first and second capacitors.
The structure is as follows.
[0034]
According to such a structure as the capacitor device, the vibration resistance is greatly improved by the amount of soldering and fixing to the printed circuit board by the above four leads, and there is no need for reinforcement or the like. Vibration resistance specifications and the like as electronic components used in the electronic control device are easily cleared.
[0035]
In the capacitor device having such a structure, as in the invention according to claim 2,
The package includes spacer means for forming a mounting gap between the bottom surface from which the leads of the first and second capacitors are led out and the printed circuit board surface.
If the above structure is also adopted, the stress caused by the difference in thermal expansion coefficient between the printed circuit board and the capacitor device body in the above-described cooling cycle etc. is also suitably absorbed by the formed mounting gap or the spacer means itself. Will come to be. Therefore, in this case, the occurrence of the solder crack or the like is also preferably suppressed, and the electrical reliability as the capacitor device is preferably maintained.
[0036]
Further, in the structure of the invention according to claim 2, and according to the invention according to claim 3,
The leads of the first and second capacitors are made of highly flexible conductor wires.
By adopting such a configuration together, the stress is absorbed by the lead itself, and the probability of occurrence of solder cracks and the like is further reduced. Examples of such highly flexible conductor wires include copper wires.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of a capacitor device according to the present invention.
Similarly to the capacitor device illustrated in FIG. 6, the capacitor device of this embodiment is also provided as a charge capacitor for pilot injection and main injection in the driver (FIG. 4) of the fuel injection control system having a pilot injection function. This is a package of two capacitors to be obtained.
[0038]
Hereinafter, based on FIG. 1, the structure of the capacitor | condenser apparatus concerning the embodiment is explained in full detail.
Also in FIG. 1, FIG. 1 (a) is a front view when this capacitor device is mounted on a printed circuit board PWB, and FIG. 1 (b) is also a side view thereof, and FIG. ) Is a bottom view showing a bottom structure of the capacitor device.
[0039]
Now, in this embodiment, in the fuel injection control system having the pilot injection function, as mentioned above, it is noted that the two capacitors for pilot injection and main injection are essential, and these two capacitors are used. Are hermetically fixed to one package.
[0040]
That is, in the capacitor device according to the embodiment shown in FIGS. 1A to 1C, the capacitors 41 and 42 arranged in the package PK are respectively in the driver 4 (FIG. 4), A capacitor charged with high voltages for pilot injection and main injection. Each of these capacitors 41 and 42 is a large-capacity film capacitor satisfying the above-mentioned specifications such as a withstand voltage of 110 V or more and a capacitance of 10 μF, and these are sealed and fixed by the filler FL in the package PK. Yes.
[0041]
For this reason, when mounted on the printed circuit board PWB, as shown in FIGS. 1A and 1B, the four leads R1a, R1b, R2a, and R2b of the capacitors 41 and 42 are mounted on the printed circuit board PWB. It will be fixed by soldering, and its vibration resistance will be greatly improved.
[0042]
In the capacitor device according to the embodiment, when the package PK is mounted on the printed circuit board PWB, a gap is formed between the bottom surface from which the leads of the capacitors 41 and 42 are led out and the surface of the printed circuit board PWB. A spacer SP is formed.
[0043]
For this reason, even if stress is generated due to the difference in thermal expansion coefficient between the printed circuit board PWB and the capacitor device body in the above-described cooling cycle or the like, the stress is caused by the mounting gap formed by the spacer SP or the spacer SP itself. Is preferably absorbed. That is, the occurrence of cracks or the like in the solder HP is suitably suppressed.
[0044]
Incidentally, in this regard, when a cooling / heating cycle test was attempted on a prototype of the capacitor device, the number of cycles until cracking occurred in the solder HP was approximately that of the structure illustrated in FIG. It was confirmed that the improvement was twice.
[0045]
In this trial manufacture, PBT (polybutylene terephthalate) resin was used as the material of the package PK, and epoxy resin was used as the filler FL. The leads R1a, R1b, R2a, and R2b of the capacitors 41 and 42 are pitch-adjusted with a jig or the like before the filler FL is cured.
[0046]
Further, in this trial production, as the leads R1a, R1b, R2a, and R2b of the capacitors 41 and 42, copper wires that are highly flexible conductor wires are used in place of the steel wires. In this case, the stress is absorbed by each of the leads.
[0047]
The size of the package PK is 33.5 mm long × 33 mm wide × 31 mm high (of which 1.5 mm is the height of the spacer SP), but only by mounting such a capacitor device without any reinforcement. It has been confirmed by experiments that the vibration-resistant specifications required for electronic components used in the on-vehicle electronic control device are easily cleared.
[0048]
As described above, according to the capacitor device according to this embodiment,
(A) The pilot-injection capacitor 41 and the main-injection capacitor 42 are hermetically fixed to one package PK and fixed to the printed circuit board PWB by the four leads of the capacitors 41 and 42. As a result, the vibration resistance is greatly improved.
(B) By providing the package PK with a spacer SP that forms a mounting gap between the bottom surface from which the leads of the capacitors 41 and 42 are led out and the surface of the printed circuit board PWB, the capacitor device body and the printed circuit board PWB are provided. The stress resulting from the difference in the thermal expansion coefficient from the above is also suitably absorbed. For this reason, the occurrence of solder cracks and the like is suitably suppressed, and the electrical reliability as the capacitor device is also suitably maintained.
(C) By using a highly flexible conductor wire such as a copper wire as the leads of the capacitors 41 and 42, the probability of occurrence of the solder cracks is further reduced.
Many excellent effects can be achieved.
[0049]
In the capacitor device according to the embodiment, as shown in FIG. 1, the spacers SP are arranged at the bottom four corners of the package PK. In addition, as shown in FIG. 2, a structure in which the spacers SP are disposed on the entire bottom side of the package PK can be appropriately employed.
[0050]
That is, the spacer SP may be anything as long as it can form a mounting gap between the bottom surface from which the leads of the capacitors 41 and 42 of the package PK are led out and the surface of the printed circuit board PWB. .
[0051]
Further, as the material of the package PK and the filler FL, any material that is not limited to the above-described PBT resin or epoxy resin can be adopted.
Furthermore, it goes without saying that any suitable conductor wire, not limited to the copper wire, can be used as each lead of the capacitors 41 and 42 as long as it is a highly flexible conductor wire.
[Brief description of the drawings]
FIG. 1 is a three-side view showing an embodiment of a capacitor device used in an on-vehicle electronic control device according to the present invention.
FIG. 2 is a trihedral view showing another embodiment of the capacitor device.
FIG. 3 is a block diagram showing a configuration of a fuel injection control system as an object of the invention.
FIG. 4 is a circuit diagram showing a driver configuration of the fuel injection control system.
FIG. 5 is a time chart showing an example of injection control by the fuel injection control system.
FIG. 6 is a three-side view showing an example of a capacitor device used in the system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 ... Buffer, 3 ... Microcomputer, 4 ... Driver, 5 ... Power supply circuit, 6 ... Solenoid valve (injector drive solenoid valve), 41 ... Pilot injection charge capacitor, 42 ... Main injection charge capacitor, 43 ... Gate circuit 44 ... Charge circuit 45 ... Charge completion determination circuit 46 ... Energization control circuit 47 ... Pilot injection charge capacitor separation circuit 48 ... Main injection charge capacitor separation circuit 49 ... Constant current circuit PWB ... Print Substrate, PK ... package, SP ... spacer, FL ... filler, Ra, Rb, R1a, R1b, R2a, R2b ... capacitor lead, HP ... solder.

Claims (3)

A capacitor device used in a fuel injection control system having a pilot injection function,
A first capacitor charged with a high voltage for pilot injection and a second capacitor charged with a high voltage for main injection are arranged opposite to each other in parallel, and are drawn from the first and second capacitors. In- vehicle electronics characterized in that four leads are hermetically fixed in one package so as to form a square shape, and are soldered and fixed to a printed circuit board by the four leads of the first and second capacitors. Capacitor device used for control devices . In the capacitor device used for the on- vehicle electronic control device according to claim 1,
The package is used for automotive electronic control apparatus characterized by comprising a spacer means to form a mounting gap between the first and second bottom and the printed circuit board surface which capacitor leads are derived capacitor device to be. In the capacitor device used for the on- vehicle electronic control device according to claim 2,
The lead of said 1st and 2nd capacitor | condenser consists of a highly flexible conductor wire. The capacitor | condenser apparatus used for the vehicle-mounted electronic control apparatus characterized by the above -mentioned .

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