JP5754408B2 - Fuel injection device - Google Patents

Description

  The present invention relates to a fuel injection device that supplies high-pressure fuel to an internal combustion engine.

  A conventional fuel injection device includes a fuel filter that filters fuel. In the fuel filter described in Patent Document 1, the fuel flow rate at each part in the fuel filter is made uniform so that dust is uniformly trapped over the entire area of the filter filter paper, so that the long life of the fuel filter is achieved. We are trying to make it.

JP 2009-197686 A

  However, in the conventional fuel filter, since all dust is finally trapped by the filter paper, the life of the fuel filter is determined by the maximum dust collection capacity of the filter paper.

  In view of the above points, an object of the present invention is to further extend the life of a fuel filter.

  In order to achieve the above object, according to the first aspect of the present invention, in the fuel injection device, the fuel filtered by the fuel filter (3) is pressurized by the pump (4) and supplied to the internal combustion engine (1). The fuel filter includes a first filter (34) made of non-woven fabric, a filter holder (35) in which a fuel inflow hole (351b) is formed below to accommodate the first filter, an upstream side of the first filter and the first filter. A second filter (36) disposed below one filter, the second filter having a compression coil spring (361) whose upper end surrounds the fuel inflow hole and is in close contact with the filter holder, and a lower end of the compression coil spring And a bottom plate (9) 362 that closes the side, and the fuel is configured to flow between the windings of the compression coil spring from the outer periphery side of the compression coil spring and flow into the inner periphery side of the compression coil spring. Features .

  According to this, due to the flow resistance when the fuel passes between the windings of the compression coil spring, a differential pressure is generated between the inner peripheral side and the outer peripheral side of the compression coil spring, and the compression coil spring is caused by the differential pressure. Since the gap between the windings of the compression coil spring shrinks, the dust having a particle size larger than the gap between the windings is captured on the outer peripheral surface of the compression coil spring.

  When the pump is stopped by stopping the internal combustion engine, no differential pressure is generated between the inner peripheral side and the outer peripheral side of the compression coil spring, and the compression coil spring extends to the natural length. The dust trapped on the surface is separated from the compression coil spring, and the dust settles by its own weight and accumulates in the lower space of the fuel filter.

  Therefore, the large particle size dust captured by the second filter is stored in the lower space of the fuel filter, and the first filter captures only the small particle size dust that could not be captured by the second filter. Therefore, the life of the first filter is extended. Moreover, since the maximum dust collection capacity of the fuel filter as a whole is larger than the maximum dust collection capacity of the first filter alone, the life of the fuel filter can be extended.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure which shows the structure of the fuel-injection apparatus which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the state in the internal combustion engine operation | movement in the fuel filter of FIG. It is sectional drawing which shows the state at the time of the internal combustion engine stop in the fuel filter of FIG. It is sectional drawing which shows the structure of the fuel filter in the fuel-injection apparatus which concerns on 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. As shown in FIG. 1, a fuel injection device that supplies fuel to an internal combustion engine 1 (more specifically, a diesel engine) includes a fuel tank 2 that stores fuel and a fuel filter that filters fuel pumped from the fuel tank 2. 3, a supply pump 4 that pressurizes the fuel filtered by the fuel filter 3, a common rail 5 that stores the fuel that has been pressurized by the supply pump 4, and a high-pressure fuel supplied from the common rail 5 Electronic control for controlling the operation of the injector 6 injected into the combustion chamber, the return path 7 for returning the fuel in the common rail 5 to the fuel filter 3, the return path on-off valve 8 for opening and closing the return path 7, the return path on-off valve 8 and the like A device 9 is provided.

  The supply pump 4 is a feed pump 41 that pumps fuel from the fuel tank 2, a high-pressure pump 42 that pressurizes and supplies the fuel supplied from the feed pump 41 to the common rail 5, and a fuel flow rate that is supplied from the feed pump 41 to the high-pressure pump 42. The intake metering valve 43 and the like are provided.

  The feed pump 41 and the high pressure pump 42 are driven by the internal combustion engine 1. The intake metering valve 43 is a linear solenoid type electromagnetic valve configured such that the valve opening can be continuously changed according to the applied current, and is controlled by the electronic control unit 9.

  The electronic control unit 9 includes a microcomputer including a CPU, ROM, EEPROM, RAM, and the like (not shown), and performs arithmetic processing according to a program stored in the microcomputer.

  The electronic control unit 9 calculates the target discharge amount of the high-pressure pump 42 so that the actual rail pressure in the common rail 5 follows the target rail pressure corresponding to the injection pressure, and performs the intake metering so that the target discharge amount becomes the target discharge amount. The opening degree of the valve 43 is controlled.

  Further, the electronic control unit 9 drives the injector 6 by determining an optimal injection timing, injection amount, etc. according to the operating state of the internal combustion engine 1 based on various input signals. Furthermore, the electronic control unit 9 drives the return path opening / closing valve 8 based on various input signals.

  As shown in FIGS. 2 and 3, the fuel filter 3 has a cylindrical shape and is installed so that the axial direction becomes the direction of gravity when in use. The fuel filter 3 is mounted on the vehicle body.

  The fuel filter 3 includes a case 31 that forms a cylindrical space inside. A fuel inlet pipe 32 into which fuel from the fuel tank 2 flows and a fuel outlet pipe 33 from which fuel flows out toward the feed pump 41 are provided at the upper part of the case 31. The fuel inlet pipe 32 may be provided, for example, in the lower part of the case 31.

  Inside the case 31, a first filter 34 made of a non-woven fabric that collects dust mixed in the fuel, a filter holder 35 that accommodates the first filter 34, and a first filter that collects dust mixed in the fuel. Two filters 36 are arranged.

  The filter holder 35 includes a disc-shaped holder plate 351 that divides the internal space of the case 31 into two vertically and a bottomed cylindrical holder cup 352 disposed above the holder plate 351. The first filter 34 is accommodated in the space formed by the holder plate 351 and the holder cup 352.

  On the outer peripheral side of the holder plate 351, a plurality of fuel passage holes 351a that allow the fuel to pass through the upper space and the lower space of the case 31 are formed. A fuel inflow hole 351b through which fuel flows into the space in which the first filter 34 is accommodated is formed at the center in the radial direction of the holder plate 351.

  The holder cup 352 has an open end that surrounds the fuel inflow hole 351b and is joined to the holder plate 351, and a fuel outlet pipe 33 is connected to the bottom.

  The second filter 36 is disposed in the lower space of the case 31. More specifically, the second filter 36 is disposed on the upstream side of the first filter 34 and below the first filter 34.

  The second filter 36 includes a compression coil spring 361 and a bottom plate 362 that closes the lower end side of the compression coil spring 361. The upper end side of the compression coil spring 361 is joined in close contact with the holder plate 351 so as to surround the fuel inflow hole 351b. The fuel passes between the windings of the compression coil spring 361.

  Next, the operation of this embodiment will be described. The arrows in FIGS. 2 and 3 indicate the flow of fuel.

  First, during operation of the internal combustion engine 1, fuel is pumped from the fuel tank 2 by the feed pump 41. The fuel pumped up from the fuel tank 2 flows into the fuel filter 3 from the fuel inlet pipe 32.

  The fuel that has flowed into the fuel filter 3 passes between the windings of the compression coil spring 361 from the outer peripheral side of the compression coil spring 361 in the second filter 36 and flows into the inner peripheral side of the compression coil spring 361.

  At this time, as shown in FIG. 2, due to the flow resistance when the fuel passes between the windings of the compression coil spring 361, a differential pressure is generated between the inner peripheral side and the outer peripheral side of the compression coil spring 361, The compression coil spring 361 contracts due to the differential pressure, and the gap between the windings of the compression coil spring 361 becomes small. Therefore, dust having a particle size larger than the gap between the windings is included in the dust contained in the fuel. Captured by the surface.

  The fuel that has flowed into the inner peripheral side of the compression coil spring 361 flows into the space in which the first filter 34 is accommodated via the fuel inflow hole 351b of the holder plate 351, and the particle size that could not be captured by the second filter 36. Small dust is captured by the first filter 34.

  The fuel that has passed through the first filter 34 flows out from the fuel outlet pipe 33 toward the feed pump 41.

  When the internal combustion engine 1 is stopped, the feed pump 41 is also stopped, so that no differential pressure is generated between the inner peripheral side and the outer peripheral side of the compression coil spring 361. Therefore, as shown in FIG. The spring 361 extends to the natural length.

  When the compression coil spring 361 extends, the compression coil spring 361 vibrates in the vertical direction, whereby the dust captured on the outer peripheral surface of the compression coil spring 361 is separated from the compression coil spring 361, and the dust is caused by its own weight. It sinks and accumulates in the lower part of the case 31.

  It should be noted that the thickness of the bottom plate 362 of the second filter 36 is varied depending on the part, and the center of gravity of the bottom plate 362 is eccentric with respect to the axis of the compression coil spring 361 so that the compression coil spring 361 is expanded when the compression coil spring 361 extends. 361 also vibrates in the horizontal direction, and dust separation is promoted.

  Further, when the internal combustion engine 1 is stopped, the electronic control unit 9 opens the return path opening / closing valve 8. By opening the return path opening / closing valve 8, the fuel in the common rail 5 is returned to the fuel filter 3 via the return path 7, and the fuel passes through the first filter 34 and passes through the inner periphery of the compression coil spring 361. Flows into the side. Further, the fuel that has flowed into the inner peripheral side of the compression coil spring 361 passes between the windings of the compression coil spring 361 and flows into the outer peripheral side of the compression coil spring 361.

  The separation of dust trapped on the outer peripheral surface of the compression coil spring 361 is promoted by the flow of fuel passing between the windings of the compression coil spring 361. Further, the flow of fuel from the inner peripheral side of the compression coil spring 361 toward the outer peripheral side suppresses the inflow of dust to the inner peripheral side of the compression coil spring 361 during the dust settling process.

  According to this embodiment, dust having a large particle size captured by the second filter 36 is stored in the lower part of the fuel filter 3, and the first filter 34 has a small particle size that could not be captured by the second filter 36. Since only dust is captured, the life of the first filter 34 is extended.

  Moreover, since the maximum dust collection capacity of the fuel filter as a whole is larger than the maximum dust collection capacity of the first filter alone, the life of the fuel filter 3 can be extended.

  Incidentally, when the gap between the windings of the compression coil spring 361 when the compression coil spring 361 contracts due to the differential pressure is set to 13 μm, about 30% of the dust in the fuel is captured by the second filter 36 and about 70%. % Was captured by the first filter 34.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, the configuration of the fuel filter 3 is changed, and the other parts are the same as those in the first embodiment. Therefore, only different parts will be described.

  As shown in FIG. 4, the bottom plate 362 of the second filter 36 is formed with an opening 362 a that communicates the inner peripheral side of the compression coil spring 361 and the outside of the compression coil spring 361. The opening 362a is opened and closed by a flap 37. Further, the flap 37 is urged by a flap spring 38 in a direction to close the opening 362a.

  The flap spring 38 is a torsion spring having arm portions at both ends, and one arm portion is joined to the bottom plate 362 and the other arm portion is joined to the flap 37.

  Next, the operation of this embodiment will be described. During the operation of the internal combustion engine 1 (see FIG. 1), the flap 37 is biased by the flap spring 38 and the opening 362a is closed. Therefore, as in the first embodiment, the compression coil spring 361 contracts due to the differential pressure generated between the inner peripheral side and the outer peripheral side of the compression coil spring 361, and the dust contained in the fuel is larger than the gap between the windings. Dust having a large particle diameter is trapped on the outer peripheral surface of the compression coil spring 361.

  When the internal combustion engine 1 is stopped, the feed pump 41 (see FIG. 1) is also stopped, so that no differential pressure is generated between the inner peripheral side and the outer peripheral side of the compression coil spring 361. Accordingly, as in the first embodiment, the compression coil spring 361 extends to a natural length, and the compression coil spring 361 vibrates in the vertical direction, so that dust captured on the outer peripheral surface of the compression coil spring 361 is compressed coil spring. 361.

  Further, when the internal combustion engine 1 is stopped, as in the first embodiment, the electronic control unit 9 (see FIG. 1) opens the return path on-off valve 8 (see FIG. 1). The separation of dust trapped on the outer peripheral surface of the compression coil spring 361 is promoted by the flow of fuel passing between the windings of the compression coil spring 361 accompanying the opening operation of the return path opening / closing valve 8.

  Further, the opening operation of the return path opening / closing valve 8 causes the fuel in the common rail 5 (see FIG. 1) to be returned to the fuel filter 3 via the return path 7 (see FIG. 1), and the inner circumference of the compression coil spring 361 Side pressure rises. Then, as shown in FIG. 4, the flap 37 opens the opening 362 a against the urging force of the flap spring 38 due to the differential pressure between the inner peripheral side of the compression coil spring 361 and the outside of the compression coil spring 361. Operates in the opening direction. As a result, the dust accumulated on the upper surfaces of the bottom plate 362 and the flap 37 is discharged from the opening 362a, and the dust settles by its own weight and accumulates in the lower portion of the case 31.

  By the way, when the internal combustion engine 1 is stopped, dust flowing into the inner peripheral side of the compression coil spring 361 and dust separated from the first filter 34 may accumulate on the upper surface of the bottom plate 362. When the force applied to the compression coil spring 361 due to the weight of the accumulated dust becomes larger than the force due to the differential pressure during operation of the internal combustion engine 1, the compression coil spring 361 expands and the gap between the windings becomes large. The dust having a particle size that should be captured by the compression coil spring 361 cannot be captured.

  Here, in the present embodiment, when the internal combustion engine 1 is stopped, the flap 37 opens the opening 362a, and dust accumulated on the bottom plate 362 and the upper surface of the flap 37 is discharged from the opening 362a. Problems due to the weight of accumulated dust can be avoided.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Fuel filter 4 Pump 34 1st filter 35 Filter holder 36 2nd filter 361 Compression coil spring 362 Bottom plate 351b Fuel inflow hole

Claims (3)

In the fuel injection device for supplying the fuel filtered by the fuel filter (3) to the internal combustion engine (1) by increasing the pressure by the pump (4),
The fuel filter includes a first filter (34) made of a non-woven fabric, a filter holder (35) in which a fuel inflow hole (351b) is formed below to accommodate the first filter, and an upstream side of the first filter. And a second filter (36) disposed below the first filter,
The second filter includes a compression coil spring (361) whose upper end surrounds the fuel inflow hole and is in close contact with the filter holder, and a bottom plate (362) that closes the lower end of the compression coil spring. A fuel injection device configured to pass between windings of the compression coil spring from the outer peripheral side of the compression coil spring and flow into the inner peripheral side of the compression coil spring. A common rail (5) for storing fuel that has been pressurized by the pump;
A return path (7) for returning the fuel in the common rail to the inner peripheral side of the compression coil spring;
The fuel injection device according to claim 1, further comprising a return path on-off valve (8) that opens the return path when the internal combustion engine is stopped. An opening (362a) that is formed in the bottom plate and communicates the inner peripheral side of the compression coil spring and the outside of the compression coil spring;
A flap (37) for opening and closing the opening;
The fuel injection device according to claim 2, further comprising a flap spring (38) for urging the flap in a direction in which the flap closes the opening.

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