JP2000018123A - Auxiliary circuit unit of fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary circuit unit of a fuel pump that prevents various kinds of malfunction when it is disposed around the pump. SOLUTION: An auxiliary unit is disposed in the vicinity of a fuel pump and accommodates a circuit substrate for controlling to drive the fuel pump within a case 7. A substrate 5 is disposed within the case which is filled with resin. A through hole 5a for resin insertion is formed in a predetermined position of the circuit substrate. A connection terminal connected to the substrate through the case is formed by piercing through a grommet interposed between the case 7 and the terminal. Associated parts mounted on the circuit substrate 5 are arranged at positions where either high or low stress is expected to be applied in accordance with the importance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary circuit unit provided near a fuel pump and containing a circuit board for controlling the driving of the fuel pump in a case.

[0002]

2. Description of the Related Art In recent years, an electronic operation control has been used in an internal combustion engine as a power source of a vehicle or the like for the purpose of improving engine performance such as fuel efficiency and reduction of exhaust gas.

That is, for example, the above-described object is achieved by finely and appropriately controlling the timing of supplying fuel into the combustion chamber of the engine and the amount of supplied fuel in accordance with external conditions and required conditions. Like that.

[0004] Such a control system is realized by using an electronic fuel injection pump.

The actuator mounted on such a fuel injection pump basically includes: 1) an injection amount adjusting section (governor actuator);
There is an injection timing adjustment unit (timer / actuator)
Conventional injection pump systems include an injection pump-governor or a timer-control unit (ECU).

Further, the ECU stores control software for controlling the operation of each unit, and also includes an actuator position detection circuit and an actuator drive circuit necessary for feedback control for reflecting the operation result on a control schedule. .

[0007]

However, problems due to control errors caused by the transmission of signals for driving sensors and actuators cannot be neglected because of the need for high engine speed and the need for more sophisticated and delicate control. I was

That is, the respective circuit groups for driving the sensor and the actuator are electrically connected to each other via a cable, but the electrical characteristics of these cables are not uniform.

This is because the length of the cable varies depending on the environment and the model in which the fuel pump is used.
This is because the impedance cannot be specified.

Further, for example, particularly in a so-called rack sensor for detecting a position by an oscillation signal, signal transmission becomes inaccurate due to impedance such as inductance and resistance of the sensor cable itself, A control error occurs.

Therefore, it has been proposed to dispose the oscillating portion and the drive circuit of such a position detection sensor in a location near the sensor, that is, in a location near the fuel pump where the sensor is located (for example, JP-A-59-160040
No.).

That is, it is intended to eliminate such a control error by arranging a sensor driving circuit or the like very close to the governor or the timer actuator.

However, actually, at a location near the sensor, that is, at a location near the fuel pump where the sensor is disposed,
It is difficult to dispose these circuits because the location where the fuel pump is located is also the location near the engine, because of poor environmental conditions such as temperature and vibration.

In particular, the connection terminals of the circuit components mounted on the circuit board may be broken due to mechanical resonance,
There is a disadvantage that the reliability of signal transmission is reduced.

Accordingly, an object of the present invention is to provide an auxiliary circuit unit of a fuel pump in which various disadvantages are reduced in order to realize such an arrangement in the vicinity.

[0016]

According to a first aspect of the present invention, there is provided an auxiliary circuit unit provided near a fuel pump and accommodating a circuit board for controlling driving of the fuel pump in a case. A circuit is provided in the case, the resin is sealed in the case by filling the resin, and an auxiliary circuit of a fuel pump having a through hole for inserting a resin at a predetermined position of the circuit board. Unit.

As described above, when the resin is filled, there are two types of resin: the resin that goes around the substrate and reaches the rear side of the substrate and the resin that passes through the through hole and reaches the rear side of the substrate. Since these two paths maintain the balance of resin encapsulation, the substrate is prevented from laterally displacing the case.

Accordingly, for example, the reference position of the sensor installed on the substrate can be maintained, so that the sensor performance can be sufficiently exhibited.

In particular, in the case where a through hole is provided in the vicinity of the sensor installed on such a substrate, the resin filling property on the back side near the sensor is improved.
This lateral displacement prevention effect is more directly promoted.

According to a second aspect of the present invention, there is provided an accessory circuit unit provided near a fuel pump and accommodating a circuit board for controlling driving of the fuel pump in the case. A resin pump is enclosed, and a connection terminal connected to the substrate through the case is provided as an accessory circuit unit of the fuel pump in which a grommet interposed in the case is inserted and provided.

As described above, since the connection terminal is inserted into the case using the grommet, the mounting hole for the grommet provided in the case is closed, so that when the resin is filled, the case is removed from the mounting hole through the mounting hole. Resin can be prevented from leaking.

In particular, when the grommet is extended in the direction of the connection terminal, most of the connection terminal located in the resin can be covered with the grommet, so that the portion of the connection terminal exposed to the resin is reduced. External force applied directly to the connection terminal from the resin can be reduced.

That is, since such an external force can be absorbed and reduced by the grommet, the thermal stress applied to the joint portion between the connection terminal and the substrate at the time of hardening of the resin after filling the resin and during normal use is reduced, and the electric force is reduced. Connection reliability can be improved.

Further, for the same reason, the impact resistance can be improved.

According to a third aspect of the present invention, there is provided an auxiliary circuit unit provided in the vicinity of a fuel pump and containing a circuit board for controlling the driving of the fuel pump in a case, the circuit board being mounted on the circuit board. The related component is an auxiliary circuit unit of the fuel pump configured to be disposed at a place where a predicted stress state is low or at a place where the stress state is high, depending on its importance.

As described above, when an important functional component is arranged at a low stress location on the substrate, the influence of the stress applied to the important functional component is reduced as much as possible, and the important functional component can be protected. The normal operation of the parts can be ensured.

In particular, it is possible to prevent malfunctions due to stress of functional components having severe use conditions, for example, custom ICs and sensors, and to improve the reliability of the entire device.

Further, since the failure starts from a minor fault that can be diagnosed, safety can be improved. That is, even if a large stress is generated, the lightly functional component starts to be broken, so that it is possible to take measures before a serious failure occurs.

As described above, according to the accessory circuit unit of the present invention, sufficient reliability can be ensured even under poor environmental conditions such as temperature and vibration.

[0030]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a fuel pump according to an embodiment of the present invention; FIG.

In this embodiment, although the fuel pump is not shown, the fuel pump is an electronic fuel injection pump for supplying fuel to an internal combustion engine of a vehicle or the like. The auxiliary circuit unit of the fuel pump according to the present embodiment is arranged near the fuel injection pump.

As shown in FIGS. 1 to 4, the accessory circuit unit 1 of this embodiment accommodates at least a circuit board 5 constituting an actuator drive circuit of an injection pump and a circuit for sensor control in a case 7. It is composed.

That is, a flat circuit board 5 having a shape similar to the shape of the opening of the case 7 and having a slightly small planar shape is placed in the case 7 formed in a predetermined shape with the upper opening.
Is stored.

Sensors and various circuit components are mounted on the circuit board 5 of the accessory circuit unit 1, and connectors for electrically connecting to external devices are also provided. The case 7 is sealed with resin.

In this embodiment, the circuit board 5 housed in the case 7 is filled with resin,
The board 5 and the circuit components mounted on the board 5 are strengthened and fixed, the circuit components and the connection between the components and the board 5 are protected, and the impact resistance is improved.

A predetermined diameter of the circuit board 5 is provided with a through hole 5a having a predetermined diameter. By filling the resin in the through-hole 5a, a so-called wedge function after filling the resin is achieved, and a slight displacement of the substrate 5 with respect to the case 7 can be prevented. Further, since the resin is filled from the through-hole 5a due to the presence of the through-hole 5a, the resin filling property is improved.

That is, this resin encapsulation is performed by temporarily assembling the substrate 5 on which circuit components have been mounted in advance in the case 7, filling the resin in a flowing state, and curing the resin after a lapse of a predetermined time.

When the resin is filled, the resin in the flowing state is also filled from the case opening side and goes around the back surface of the substrate 5 through the periphery of the substrate 5. In the case of the conventional example that does not exist, the amount of the resin wrap around the entire periphery of the substrate 5 is not uniform due to the planar shape of the substrate 5 itself or a gap generated between the planar shape of the substrate 5 and the planar shape of the case 7. And the substrate 5
Was slightly shifted laterally with respect to case 7. If the reference position of the sensor mounted on the board that detects the operating position is slightly shifted due to the lateral shift of the board 5, an error that cannot be specified from the beginning is included, and as a result, the detection accuracy is reduced. Since the error of (1) increases and the sensor performance deteriorates, it is necessary to perform a sensor calibration process and the like and a correction process of the detection result.

Conventionally, the substrate 5
If the filling pressure of the resin is increased in order to improve the filling degree of the resin in the gap with the case 7 on the lower side, this tendency may be promoted.

As described above, in this embodiment, since the through holes 5a for preventing the lateral displacement of the substrate 5 are provided at predetermined positions of the substrate 5, such a situation can be avoided beforehand.

Further, since the lateral displacement of the substrate 5 can be sufficiently prevented, the reference position of the sensor installed on the substrate 5 can be maintained, and the sensor performance can be sufficiently exhibited.

In particular, when such a through-hole 5a is provided in the vicinity of a sensor installed on a substrate,
Since the resin filling property on the back side near the sensor is improved, the effect of preventing the lateral displacement is more directly promoted.

Further, since the resin filling property on the back side of the substrate 5 is improved in this manner, the workability in resin filling can also be improved.

Next, in this example, the lead pin 11 which penetrates through the case 7 and passes through the resin portion and is connected to the substrate 5 is provided, and the grommet 9 for the lead pin 11 is provided. In addition to preventing the resin from leaking out of the case at the time of filling the filled resin, the lead pin 11 at the time of curing the resin after filling the resin and during normal use is used.
The thermal stress applied to the joint with the substrate 5 is reduced.

This grommet 9 is shown in FIGS.
As shown in (1) and (2), for example, a flexible material having sufficient electrical insulation and excellent heat resistance, such as synthetic rubber, is provided in the case 7. The grommet 9 is formed in a shape corresponding to the opening shape of the grommet mounting hole 7a, and the grommet 9 has a mounting hole 9d for a lead pin.
Is provided.

That is, the grommet 9 has the same cross-sectional shape as the fitting portion 9 a formed in an oval shape slightly larger than the oval grommet mounting hole 7 a provided in the case 7. An elliptical flange 9b having a predetermined width and a protective part 9c formed substantially in the shape of an ellipse substantially similar to the fitting part 9a, and a mounting hole 9d for a lead pin is provided in a substantially central part thereof. Is provided.

The protection part 9c of the grommet 9 is
The tip of the grommet 9 is set so as to extend to a position near the substrate 5 provided in the case, and a relatively small gap or a gap between the two is eliminated between the tip of the grommet 9 and the substrate 5. .

Therefore, using the grommet 9 made of this flexible material, the lead pin 11 is inserted into the case,
Since the grommet mounting hole 7a provided in the case 7 is closed, the resin can be prevented from leaking from the grommet mounting hole 7a to the outside of the case when the resin is filled, and the manufacturability can be improved. .

That is, the grommet 9 is pressed into the grommet mounting hole 7a from the inside of the case, and the fitting portion 9a of the grommet 9 is tightly fitted to the grommet mounting hole 7a to prevent a gap from being formed between them. Further, since the collar portion 9b covers the joint portion between the two, the collar portion 9b can be sufficiently closed, and the resin can be prevented from leaking out of the case.

Further, since the grommet 9 covers most of the lead pin 11 located in the resin in the longitudinal direction, the exposed portion of the lead pin 11 to the resin is reduced, and external force applied directly to the lead pin 11 from the resin is reduced. Can be reduced.

That is, such an external force can be absorbed and relieved by the grommet 9 made of a flexible material, so that the resin can be hardened after the resin is filled, and the lead pin 11 can be bonded to the board 5 during normal use. The applied thermal stress is reduced, and the electrical connection reliability can be improved.

For the same reason, the impact resistance can be improved.

Next, in this example, the arrangement of the electric components mounted on the circuit board 5 on the circuit board is determined according to the importance of each component, and the reliability as a whole is sufficiently high. They are trying to be safe and secure.

That is, a custom IC or an important part which becomes a serious failure when damaged is a part of the substrate 5 where the stress is the smallest in the stress distribution of the substrate 5 obtained by the thermal stress analysis (see FIG. 7). The parts with relatively light functions are arranged in other places.

In particular, it is possible to diagnose a failure from the outside,
In addition, components having relatively light functions are arranged in places other than the places where low stress occurs on the substrate.

This is because, as shown in FIG. 7, the stress applied to the substrate 5 is large at the peripheral portion of the substrate 5 (portion without hatching in FIG. 7), and near the center portion (portion with hatching having a small width in FIG. 7). Then, it can be understood from the simulation results that the stress is reduced. In FIG. 7, from the hatched portion with a narrow width to the portion without hatching, from the one with the smaller hatching width to the one with the larger hatching, and finally to the one without the hatching,
This shows that the applied stress increases.

Therefore, important functional components such as an external connector, a custom IC, and a sensor are arranged in a place on the substrate where a low stress occurs, and other components than these components are placed outside the low stress place. Has been placed.

Therefore, since important functional components are arranged at low stress locations on the substrate, each important functional component can be protected, and the normal operation of the component can be ensured. . In particular, for components having severe use conditions as functional components, for example, custom ICs and sensors, malfunctions due to stress applied thereto can be prevented, and the reliability of the entire device can be improved.

In addition, when a large stress occurs, it starts to break from a light functional component, that is, the fault starts from a small fault that can be diagnosed.
As a result, it is possible to improve security.

[0060]

As described above, the invention described in claim 1 of the present application is an auxiliary circuit unit provided near a fuel pump and accommodating a circuit board for controlling the driving of the fuel pump in a case. In the fuel pump, a board is disposed in the case, and resin is sealed in the case by filling the resin, and a through hole for inserting a resin is provided at a predetermined position of the circuit board. It is an attached circuit unit.

As described above, at the time of filling the resin, there are two types of resin: the resin that goes around the substrate and reaches the rear side of the substrate and the resin that passes through the through hole and reaches the rear side of the substrate. Since these two paths maintain the balance of resin encapsulation, the substrate is prevented from laterally displacing the case.

Accordingly, for example, the reference position of the sensor installed on the substrate can be maintained, so that the sensor performance can be sufficiently exhibited.

In particular, when a through hole is provided in the vicinity of the sensor installed on such a substrate, the resin filling property on the back side near the sensor is improved.
This lateral displacement prevention effect is more directly promoted.

According to a second aspect of the present invention, in an accessory circuit unit which is provided near a fuel pump and houses a circuit board for controlling the driving of the fuel pump in the case, the case is filled with resin in the case. A resin pump is enclosed, and a connection terminal connected to the substrate through the case is provided as an accessory circuit unit of the fuel pump in which a grommet interposed in the case is inserted and provided.

As described above, since the mounting terminal for the grommet provided in the case is closed while the connection terminal is inserted into the case using the grommet, when filling the resin, the mounting hole for the grommet is removed from the case. Resin can be prevented from leaking.

In particular, when the grommet is extended in the direction of the connection terminal, most of the connection terminal located in the resin can be covered with the grommet, so that the exposed portion of the connection terminal to the resin is reduced. External force applied directly to the connection terminal from the resin can be reduced. Further, for the same reason, the impact resistance can be improved.

According to a third aspect of the present invention, there is provided an auxiliary circuit unit provided near a fuel pump and accommodating a circuit board for controlling the driving of the fuel pump in a case, wherein the circuit board is mounted on the circuit board. The related component is an auxiliary circuit unit of the fuel pump configured to be disposed at a place where a predicted stress state is low or at a place where the stress state is high, depending on its importance.

As described above, when an important functional component is arranged at a low stress location on the substrate, the influence of the stress applied thereto is reduced as much as possible, and the important functional component can be protected. The normal operation of the parts can be ensured.

In particular, it is possible to prevent malfunctions due to stress of components having severe use conditions as functional parts, for example, custom ICs and sensors, and improve the reliability of the entire device.

Further, when a large stress occurs, it starts to break from a lightly functional component and starts from a small fault that can be diagnosed, so that it is possible to cope with the fault before it becomes a serious fault. Safety can be improved.

As described above, according to the accessory circuit unit of the present invention, sufficient reliability can be ensured even under poor environmental conditions such as temperature and vibration.

[Brief description of the drawings]

FIG. 1 is a front view of an auxiliary circuit unit of a fuel pump according to an embodiment of the present invention.

FIG. 2 is a plan view of the attached circuit unit of the specific example.

FIG. 3 is a longitudinal sectional view of the accessory circuit unit of the present example.

FIG. 4 is a plan view of the accessory circuit unit of the present embodiment before resin filling.

FIG. 5 is a plan view showing an arrangement of grommets according to the accessory circuit unit of the present embodiment.

FIG. 6 relates to the grommet of the accessory circuit unit of the present embodiment,
(1) is a schematic perspective view, and (2) is a partially broken perspective view.

FIG. 7 is an explanatory diagram showing a result of a stress simulation on a circuit board according to the accessory circuit unit of the present example.

[Description of Signs] 1 Attached circuit unit 5 Circuit board 5a Penetration hole of circuit board 7 Case 7a Grommet mounting hole of case 9 Grommet 9a Grommet fitting portion 9b Grommet flange 9c Grommet protection portion 9d For grommet lead pin Mounting hole 11 Lead pin A Resin

Continued on the front page F term (reference) 3G066 AA07 AB02 AD12 BA17 BA23 BA46 BA47 BA54 CA00 CD17 CE29 CE30 DC04 3G301 HA02 JA02 JA08 JA09 JA21 JA32 LB14 PB04Z

Claims (3)

[Claims] 1. An accessory circuit unit provided in the vicinity of a fuel pump and containing a circuit board for controlling the driving of the fuel pump in a case, wherein the board is arranged in the case, and the case is filled by resin. A resin pump is provided, and a through hole for inserting a resin is provided at a predetermined position of the circuit board. 2. An auxiliary circuit unit provided in the vicinity of a fuel pump and containing a circuit board for controlling driving of the fuel pump in a case, wherein the resin is filled in the case by filling the resin. A connection terminal for a fuel pump, wherein a connection terminal connected to the substrate through the case is provided by inserting a grommet interposed in the case. 3. An accessory circuit unit provided in the vicinity of a fuel pump and housing a circuit board for controlling the driving of the fuel pump in a case, wherein the related components mounted on the circuit board are of importance. The auxiliary circuit unit of the fuel pump, wherein the auxiliary circuit unit is disposed at a place where a predicted stress state is low or at a place where the stress state is high on the substrate.