JPH0739825B2 - Accumulation fuel injection device for diesel engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-accumulation type fuel injection device for a diesel engine, and more particularly, it is possible to simplify the advance angle device and to incorporate the advance angle device into the fuel supply device. In addition to increasing versatility, the mechanism of the advancement device is simplified to improve reliability, and further, operation noise due to depressurization for fuel injection, error in injection timing, and occurrence of shortage of next injection amount are prevented. The present invention relates to a pressure-accumulation fuel injection device for a diesel engine, which can be prevented and can simplify a mechanism for returning an injector, a fuel injection pump, a pump return pressure accumulation chamber, and the like to an initial state.

<Prerequisite Configuration> The present invention, for example, as shown in FIG. 1 (present invention) or FIG. 15 (prior art), uses a fuel tank 1 with a pressure adjusting device 12, a metering device 14, a shutoff valve 25, and a fuel injection pump. The fuel injection pump 26 is connected to the pressure-accumulation type fuel injector 29 via the 26, and the shutoff valve is connected to the fuel injection pump 26.
Insert the pump return pressure accumulator chamber 27 through 25, and
Was invented on the premise of a pressure-accumulation type fuel injection device of a diesel engine configured to increase the fuel supply pressure in accordance with the rotation speed of the engine. Here, as shown in FIG. 11, the pressure accumulation type fuel injector 29 means that the fuel is injected through the valve closing pressurization fuel chamber 85 and the check valve 95.
, The internal pressure of the valve closing pressurizing fuel chamber 85 is reduced, and when the internal pressure of the valve closing pressurizing fuel chamber 85 of the injector 29 falls below a predetermined value, the internal pressure of the injected fuel pressure accumulating chamber 86 becomes equal to that of the valve closing spring 91. This is an injector in which the valve closing biasing force and the internal pressure of the valve closing pressurizing fuel chamber 85 are overcome to open the injection valve 88 and the fuel in the injected fuel pressure accumulating chamber 86 is injected from the injection hole 87. The valve closing pressurizing fuel chamber 85 is normally communicated with the pump chamber 82 of the fuel injection pump 26.

<Prior Art> Conventionally, the internal pressure of the valve closing pressurizing fuel chamber 85 is reduced by opening the check valve 95 from the pump chamber 82 to press the fuel into the injected fuel pressure accumulating chamber 86 and then raising the plunger 81. To be done.
As shown in FIG. 14, the plunger 81 is lifted directly by the fuel injection cam 30 of the drive device 5 which is interlocked with the crankshaft C (shown in FIG. 2) or by the cam follower.
It is restricted via 31, push rod 32, rocker arm 33 and the like. Further, the cam follower 31 includes an eccentric shaft 106 for advancing that is rotatably supported by a wall portion 105 of the engine.
Is eccentrically supported by the eccentric shaft corresponding to the engine speed.
The contact position between the cam follower 31 and the fuel injection cam 30 is changed by rotating 106 to the advance side or the retard side, and the fuel injection timing is adjusted.

<Prior invention> In the conventional pressure-accumulation fuel injection device for a diesel engine configured as described above, as a result of the plunger 81 not rising to the top dead center at the time of partial load, operating noise occurs and the injection timing is determined with high accuracy. There was a problem that it would be difficult to do.

Then, in order to solve such a problem, the present inventor, prior to the present invention, as shown in FIG. 16, sets the fuel tank 1 of the diesel engine to the pressure adjusting device 12, the adjusting device 14,
A pressure-accumulation fuel injection device for a diesel engine, which is connected to a pressure accumulation type fuel injector 29 through a cutoff valve 25 and a fuel injection pump 26, and communicates with a fuel injection pump 26 through a cutoff valve 25 and a pump return pressure accumulation chamber 27. Invented

According to this prior invention, the fuel accumulated in the pump reciprocating pressure accumulator chamber 27 during the downward stroke of the plunger 81 is pressed into the pump chamber 82 during the ascending stroke of the plunger 81, and the plunger 81 is constantly returned to the top dead center. The above problem is solved.

However, the injection timing is determined by the drive device 5 that drives the fuel injection pump 26, and the drive device 5 has different configurations, shapes and sizes of parts, and the like depending on the size of the engine and the like. There is a problem that it is scarce. Further, since the advance device is incorporated in the drive device 5, the versatility thereof is poor.

Therefore, prior to the present invention, the present inventor has improved the following in a pressure accumulation type fuel injection device for a diesel engine having the configuration of the above-described prior invention as a second prior invention as shown in FIG. Invented something.

That is, the pressure adjusting device 12 is configured to increase the fuel supply pressure in accordance with the engine speed, and the fuel injection pump 26 is provided in the valve closing pressurizing fuel chamber 85 of the fuel injector 29.
And, the injection timing setting pressure relief valve 19 and the injection timing adjustment advance valve 20 are connected in sequence via the shutoff valve 25, and the pressure relief valve 19 depressurizes the pressure relief valve body 57 to the inlet 24 of the valve box 56. The valve valve passage 59 for communication is made to communicate, and the valve body 57 for pressure release is time-interlocked with the crankshaft C of the engine, and the advance valve 20 connects the valve body passage 59 for pressure release to the valve body 57 for pressure release. A plurality of advancing valve bodies 61 are provided along the rotation direction, and the advancing passages 62 of the advancing valve bodies 61 are selectively communicable with the plurality of advancing valve body passages 59. The angle biasing means 65 biases the retard angle side, and the fuel pressure of the advance angle pressure receiving chamber 63 biases the advance angle side to the advance angle side. The invention has invented a pressure-accumulation fuel injection device for a diesel engine that is in communication.

According to this improved prior invention, after the fuel is press-fitted into the injector 29, the pressure relief valve 19 is opened to reduce the internal pressure of the valve-closing pressurization fuel chamber 85, so that the injection valve 88 is opened. It Therefore, the injection timing is accurately determined by the timing at which the pressure relief valve body passage 59 of the pressure relief valve 19 selected by the advance valve 20 communicates with the inlet 24 of the valve box 56. Also, the advance valve body 61
Since the position of is determined depending on the internal pressure of the advance pressure receiving chamber 63 in which the fuel supply pressure can be increased by the pressure adjusting device 12 in accordance with the engine speed, the mechanism of the advance device for adjusting the injection timing is simplified. Can be converted. Furthermore, since the pressure release valve 19 and the advance valve 20 are incorporated in the fuel supply device, they can be generalized regardless of the size of the engine or the like.

<Problems to be Solved by the Invention> However, according to the improved prior invention described above, since the fuel is escaped from the valve closing pressurizing fuel chamber 85 at the time of fuel injection, the pump chamber 82 and the pump recovery chamber communicating with the fuel chamber 85 are connected. Dynamic accumulator
The fuel in 27 is lower than in the initial state, and the plunger 81
The plunger 81 cannot return to the top dead center during the ascending stroke, and as a result, a gap is created between the components of the drive device 5 or between the drive device 5 and the plunger 81 to generate operating noise. It was found that when the fuel was injected into 29, the injection amount was smaller than the adjusted amount, and there were problems such as insufficient injection amount.

The present invention has been made in consideration of the above circumstances, and can simplify the mechanism of the advance angle device and increase the versatility of the fuel injection device with the advance angle device. The mechanism of the advance device for adjusting the timing is simplified to improve reliability, and further, after the fuel injection, the injector, fuel injection pump, pump return pressure accumulating chamber, etc. can be surely returned to the initial state. An object of the present invention is to provide a pressure-accumulation fuel injection device for a diesel engine in which a mechanism for returning to a state can be simplified.

<Means for Solving the Problems> In the present invention, in order to achieve the above object in the pressure-accumulation type fuel injection device for a diesel engine having the above-described prerequisite structure, for example, as shown in FIG. 1 to FIG. The following technical measures will be taken.

That is, the injection timing setting pressure relief valve is inserted into the valve closing pressurization fuel chamber 85 of the fuel injector 29 via the fuel injection pump 26 and the shutoff valve 25.
19 and the injection timing adjusting advance valve 20 are sequentially connected, and the pressure release valve 19 has the pressure relief valve body passage 59 formed in the pressure relief valve body 57 in the inlet 24 formed in the valve box 56, The pressure relief valve body 57 is configured to be communicated intermittently, and the pressure relief valve body 57 is timed in conjunction with the crankshaft C. The advance valve 20 has a plurality of advancement relief valve body passages 62. 59, the plurality of pressure relief valve body passages 59 are formed so as to be displaced from each other in the rotational direction and the axial direction of the pressure relief valve body 57, and the advance valve body passage 62 is formed. The advancing valve body 61 is formed by running in the circumferential direction on the circumferential surface of the advancing valve body 61, and the advancing valve body 61 is formed in the depressurizing valve body 57 along the axial direction thereof. The valve body 61 is slidably fitted in the valve 60, and the advance valve body 61 is urged to the retard side by the retard urging means 65, and is also urged to the advance side by the fuel pressure in the advance pressure receiving chamber 63. The pressure receiving chamber 63 for advancing is connected to the pressure adjusting device 12. Then, the initial pressure supply passage 23 independent of the pressure relief valve body passage 59 is formed in the pressure relief valve body 57, and the starting end portion of the initial pressure supply passage 23 is communicated with the advance pressure receiving chamber 63. The end portion is configured to be intermittently timed and communicable with the introduction port 24 of the injection timing setting pressure relief valve 19.

<Operation of the Invention> According to the pressure-accumulation injection device for a diesel engine of the present invention, the injection timing setting pressure relief valve selected by the advance valve 20.
The valve body passage 59 for depressurizing 19 is timed to the crankshaft C, and the valve box 56
When it communicates with the inlet 24, the fuel in the valve closing pressurizing fuel chamber 85 is released to the outside from the pressure release valve 19, the internal pressure of the valve closing pressurizing fuel chamber 85 is reduced, and the injection valve 88 is opened to perform injection. Fuel is injected from the hole 87. The injection timing is adjusted depending on which pressure relief valve body passage 59 the advancement valve body passage 62 of the advance valve 20 communicates with. Which pressure release valve body passage 59 the advance valve body passage 62 communicates with is determined by the position of the advance valve body 61 in which the retard biasing means 65 and the fuel pressure in the advance receiving chamber 63 are balanced. Determined by The advance pressure receiving chamber 63 has a pressure adjusting device 12 configured to increase the fuel supply pressure in accordance with the rotation speed of the engine.
Since the fuel is received from, the position of the advance valve body 61 is moved to the advance side according to the rotation speed of the engine. Further, after the fuel injection is completed, the valve closing pressurization fuel chamber 85,
Since the fuel injection pump 26 and the pump return pressure accumulation chamber 27 are communicated with the pressure regulator 12 via the initial pressure supply passage 23 and the advance pressure receiving chamber 63, the valve closing pressurization fuel chamber 85, the fuel injection pump 26
Further, the fuel that has escaped at the time of injection is replenished to the pump return pressure accumulating chamber 27 from the pressure adjusting device 12, and the internal pressure of these is surely returned to the initial state.

<Examples> Examples of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the fuel system of this diesel engine measures the fuel in the fuel tank 1 by the metering and supplying device 2 in accordance with the load condition of the engine, and supplies the timing control composite valve device 3 with the timing. The fuel is supplied to the unit injector 4 at a predetermined timing via the decision valve 18, and the fuel injection pump
26 is driven by the drive unit 5 to accumulate pressure
After press-fitting into 29, the injection timing setting depressurizing valve 19 and the injection timing adjusting advance valve 20 of the timing control combined valve device 3 depressurize the fuel in the valve closing pressurizing fuel chamber 85 of the pressure accumulating fuel injector 29. The fuel is released into the breathing chamber 21 to reduce the internal pressure of the fuel chamber 85 for pressurizing the valve, and thereby the injection valve 88 is opened to inject the fuel pressure accumulation chamber 86.
Fuel is injected from the injection hole 87 through the injection hole 87, and the fuel in the depressurized fuel breathing chamber 21 is discharged back to the unit injector 4 through the depressurized fuel return passage 22 at a predetermined timing after the end of the injection to be depressurized. The reduced fuel is returned to the unit injector 4, and thereafter, the initial pressure supply passage 23 of the timing control combined valve device 3 is communicated with the unit injector 4 to return the unit injector 4 to the initial state.

As shown in FIG. 2, the metering and feeding device 2 is a transfer pump incorporated in a thick-walled cylindrical casing 6.
10, pressure regulator 12 (Fig. 4), metering device 14 and pressure pump
16, the fuel pump 1 pumps out fuel from the fuel tank 1 through a fuel pipe (not shown), an inlet joint 8 (FIG. 4) and an inlet passage 9 (FIG. 4), and transfers the fuel discharged from the transfer pump 10. The pressure is increased or decreased by the pressure adjusting device 12 in accordance with the engine speed (for example, in direct proportion), and the pressure-adjusted fuel is adjusted by the amount adjusting device 14 in accordance with the load condition of the engine, and the pressure is adjusted. The metered fuel is pumped by the pump 16 to the timing control combined valve device 3.

The transfer pump 10 has a pump chamber 34 formed at the front end portion of the casing 6, and in the pump chamber 34, as shown in FIG. 3, an inner rotor 35 fixed to the main shaft 7 penetrating the casing 6 and The eccentrically meshed outer rotor 36 is inserted into this, and the fuel is sucked from the inlet passage 9 through the suction port 37 into the space between the rotors 35 and 36, and then discharged from the discharge port 38 to the discharge passage 11 (Fig. 4). It is designed to discharge.

As shown in FIG. 4, the pressure adjusting device 12 is connected to the discharge passage 11 in a branched manner, and has a pressure adjusting plug 39 screwed to the casing 6,
A pressure regulating valve body 40 slidably fitted therein is provided, and a valve closing spring 41 for urging the pressure regulating valve body 40 to a valve closing position. A pressure regulating valve hole 42 is opened in the peripheral wall of the pressure regulating plug 39, and the pressure regulating valve hole 42 is communicated with the inlet passage 9. The discharge pressure of the transfer pump 10 corresponds to the engine speed 2
It changes in a quadratic function, and in response to this discharge pressure, the pressure regulating valve body 40 is urged against the valve closing spring 41 in the valve opening direction. This pressure regulator
In 12, by appropriately setting the opening area of the pressure regulating valve hole 42 with respect to the displacement amount of the pressure regulating valve body 40 from the closed position, the fuel escaped from the pressure regulating device 12 to the inlet passage 9 in correspondence with the rotation speed of the engine. By adjusting the amount, the internal pressure of the discharge passage 11 is accurately increased or decreased in direct proportion to the rotation speed of the engine. However, the correspondence relationship between the internal pressure of the discharge passage 11 controlled by the pressure regulator 12 and the rotation speed of the engine is not limited to the direct proportion, and for example, the increase rate of the internal pressure of the discharge passage 11 decreases as the speed increases. Alternatively, the increasing rate of the internal pressure of the discharge passage 11 may increase as the speed increases. A drain pipe joint 43 for connecting a drain pipe (not shown) for discharging fuel leaked from between the pressure regulating plug 39 and the pressure regulating valve body 40 is connected to the pressure regulating plug 39.

As shown in FIG. 2, the metering device 14 includes a metering piston 44 which is fitted in the front half of the main shaft 7 so as to be able to move forward and backward. The metering piston 44 is driven in the fuel reducing direction (here, forward) against the pressure of the governor spring 46 by the thrust of the flyweight 45 corresponding to the rotation speed of the engine. A metering valve hole 47 communicating with the discharge passage 11 is opened in the inner peripheral surface of the main shaft 7, and the metering piston hole 47 is opposed to the metering valve hole 47.
A metering valve body passage 48 is provided on the peripheral surface of the groove 44 along the entire circumference thereof. Then, as the metering piston 44 moves back and forth according to the engine speed, the connection area between the metering valve hole 47 and the metering valve body passage 48 is changed so as to correspond to the engine speed. The flow rate is adjusted and the spindle 7
Further, the fuel is guided to the pressure feed pump 16 through the outlet passage 49 formed in the casing 6. The pressure of the governor spring 46 can be changed and set by swinging the speed setting lever 50.

As shown in FIGS. 2 and 5, the pressure pump 16 has a swing arm formed by a drive cam 51 formed on the peripheral surface of the main shaft 7.
A plunger 53 driven via 52 and a pump chamber 54 whose volume changes as the plunger 53 moves forward and backward are provided. Further, the pressure pump 16 is configured to obtain pump characteristics corresponding to various torque characteristics suitable for engine applications by changing and setting the stroke of the plunger 53 by the torque characteristic setting device 55.

The timing control combined valve device 3 is incorporated in the casing 6 of the metering and feeding device 2 as shown in FIGS. 2 and 6 to 8 in order to achieve downsizing and compactness. The timing control combined valve device 3 essentially comprises a supply timing determination valve 18, an injection timing setting pressure relief valve 19, and an injection timing adjustment valve that can be provided independently as shown in FIG. The square valve 20 and the depressurized fuel breathing chamber 21 are integrally combined for downsizing and size reduction.

That is, as shown in FIG. 2 and FIGS. 6 to 8, the supply timing determination valve 18 that determines the timing at which the fuel is pressure-fed to each unit injector 4 and the injection timing setting depressurization valve 19 are the latter half of the casing 6. A common valve box 56 made up of parts and a common valve body 57 made up of the latter half of the main shaft 7 are provided. At the rear end portion of the inner peripheral surface of the casing 6, a pressure feeding passage 17 led out from the pressure feeding pump 16 of the metering supply device 2 is opened, and a passage (distributing passage = pressurization valve) to / from each unit injector 4 is opened slightly forward thereof.
19 inlets) 24 are opened at equal intervals in the circumferential direction. A communication groove portion 58a of a valve body passage 58 for determining the supply timing is recessed in the portion of the main shaft 7 facing the pressure feeding passage 17 over the entire circumference, and a passage locus of the passage 24 from one position in the circumferential direction of the communication groove portion 58a. The supply timing determining groove portion 58b is continuously extended in the axial direction along the peripheral surface up to the outer peripheral surface portion of the main shaft 7 opposed to l. Then, the main shaft 7 rotates in conjunction with a crank shaft (not shown), and the supply timing determining groove portion 58b communicates with the inlet / outlet passage 24 by overlapping inward and outward so that the supply timing determining groove portion 58b communicates from the pressure feeding passage 17 via the supply timing determining valve body passage 58. The pressure-controlled / metered fuel is press-fitted into the inlet / outlet passage 24. In addition, in the portion of the outer peripheral surface of the main shaft 7 facing the passage locus 1 of the passage 24,
The pressure release valve body passage 59 of the injection timing setting pressure release valve 19 which is communicated with the inlet / outlet passage 24 is opened at a predetermined timing after the supply timing determination groove 58b.

The latter half of the main shaft 7, which is the common valve body 57 of the supply timing determination valve 18 and the injection timing setting pressure relief valve 19, further serves as a valve box of the injection timing adjusting advance valve 20. That is, a cylindrical advancing valve chamber 60 is formed concentrically in the latter half of the main shaft 7, and an advancing valve body 61 advances and retreats in the axial direction of the main shaft 7 in the advancing valve chamber 60. It is stored as much as possible. In the valve body 57, three pressure relief valve body passages 59 whose opening positions on the inner peripheral surface are different from each other in the rotation direction and the axial direction of the main shaft 7 are formed so as to penetrate the peripheral wall thereof, and are used for advancing. An advancing valve body passage 62 is formed on the circumferential surface of the valve body 61 so as to communicate with one of the three depressurizing valve body passages 59 or two adjacent ones. The advance valve body passage 62 is formed of a circumferential groove that is recessed over the entire circumference of the advance valve body 61. The advance valve chamber 60 is divided by the advance valve body 61 into an advance pressure receiving chamber 63 and a retard urging chamber 64.
Then, the advancing pressure receiving chamber 63 is communicated with the discharge passage 11 whose pressure is regulated by the pressure regulating device 12, the retard urging chamber 64 is communicated with the inlet passage 9 which is kept at a substantially constant pressure, and Inside the biasing chamber 64, a retard urging means 65 for urging the advance valve body 61 in the retard direction is housed, and as will be described later, the position of the advance valve body 61 is set to the rotation of the engine. It is configured so that it can be controlled with high accuracy depending on the pressure regulation characteristic with respect to speed.

Here, the advance valve element 61 is moved in the axial direction and selectively communicates with the depressurizing valve element passage 59, but the advance valve element 61 corresponds to the rotational speed of the engine. The valve body 61 may be configured to rotate about the axis and selectively communicate with the pressure relief valve body passage 59.

The depressurized fuel breathing chamber 21 is formed inside the advance valve body 61 for downsizing and compactification. That is, a stepped cylindrical cavity 66 is formed inside the advance valve body 61.
66 is divided into a pressure-release fuel breathing chamber 21 and a discharge return urging chamber 68 by a piston 67 slidably fitted inside these. The discharge return urging chamber 68 communicates with the inlet passage 9 via the retard angle urging chamber 64, and the discharge return urging means 69 is housed therein. The depressurized fuel breathing chamber 21 is connected to the advance valve body passage 62 by the breathing passage 70. First, the fuel injection pump
When the plunger 81 of 26 is driven to be discharged by the fuel injection cam of the drive device 5, the fuel in the pump chamber 82 is pressurized, and passes through the valve closing pressurizing fuel chamber 85 and the check valve 95, and then the injected fuel pressure accumulating chamber. Pressed into 86.

Then, the plunger 81 is held at the discharge end position by the fuel injection cam for a certain period of time (between time points fm in FIG. 13). In this state, the check valve 95 is closed, but the valve closing pressurizing fuel chamber 85 / pump is closed. The chamber 82 and the passage 24 are maintained at a high pressure.

In this high pressure holding state, when the inlet / outlet passage 24 communicates with the depressurized fuel breathing chamber 21 through the pressure relief valve body passage 59, the advance valve body passage 62 and the breathing passage 70, the high pressure fuel on the inlet / outlet passage 24 side is communicated. The pressure causes the piston 67 to be pushed into the discharge return urging chamber 68 side, and the fuel is pressed into the depressurized fuel breathing chamber 21. As a result, the internal pressure of the valve closing pressurizing fuel chamber 85 of the pressure accumulating fuel injector 29 communicating with the inlet / outlet passage 24 is reduced, and the injection valve 88 is opened to inject fuel. At this time, the pressure in the depressurized fuel breathing chamber 21 rises by the amount of the injected fuel.

A pressure release fuel return passage 22 communicating with the inlet / outlet passage 24 is formed at a predetermined timing after the pressure release valve body passage 59 at a portion of the peripheral wall of the main shaft 7 facing the passage locus 1 of the inlet / outlet passage 24. There is. First, after the fuel injection is completed, when the plunger 81 of the fuel injection pump 26 is actuated to the suction side, the internal pressure of the pump chamber 82 is reduced and the inlet / outlet passage 24 is also reduced in pressure.

Next, in the low pressure state of the pump chamber 82 and the inlet / outlet passage 24, the pressure-removed fuel breathing chamber 21 whose pressure has been increased is passed through the breathing passage 70, the advance valve body passage 62, and the pressure-release fuel return passage 22. By being communicated with the inlet / outlet passage 24, the discharge return urging means 69 pushes the piston 67 back to the pressure-release fuel breathing chamber 21 side, and the fuel press-fitted into the pressure-release fuel breathing chamber 21 flows through the inlet / outlet passage 24 in the low pressure state. After that, it is discharged back to the unit injector 4.

Further, an initial pressure supply passage 23, which communicates with the inlet / outlet passage 24 at a predetermined timing after the depressurized fuel return passage 22, is provided in the peripheral wall portion of the main shaft 7 facing the passage locus 1 of the inlet / outlet passage 24. There is. The initial pressure supply passage 23 communicates with the discharge passage 11 whose pressure is regulated by the pressure regulating device 12.

As shown in FIGS. 1 and 11, the unit injector 4 includes a compound shutoff valve 25 connected to the inlet / outlet passage 24, a fuel injection pump 26, a pump return pressure accumulator chamber 27, and a shutoff valve return accumulator chamber 28. And a pressure-accumulation type fuel injector 29, the fuel injection pump 26 is built in the body 83 of the injector 29, and the composite cutoff valve 25
Is further built into the plunger 81 of the fuel injection pump 26.

That is, the fuel injection pump 26 has the injection pipe 84 on one side of the body 83.
Plunger 81 fitted in parallel to and vertically movable
And a pump chamber 82 partitioned by a body 83 and a plunger 81. The plunger 81 is formed in the shape of a hollow cylinder whose both ends are closed, and the internal space thereof is the valve chamber 71 of the composite shutoff valve 25.
Are configured. A spool 72 is slidably inserted in the valve chamber 71, and the spool 72 causes the valve chamber 71 to
Accumulation chamber for pump return 27 on the bottom dead center side of the moving stroke of 72
And the shut-off valve return biasing chamber 73 on the top dead center side. The shut-off valve return bias chamber 73 is a shut-off valve return accumulator chamber 28.
Is in communication with. An inner inlet / outlet passage 74 communicating with the inlet / outlet passage 24 is opened at an intermediate height portion of the peripheral wall of the plunger 81, a pump communicating passage 75 communicating with the pump chamber 82 is opened at a lower portion thereof, and a shutoff valve recovery passage is provided at an upper portion thereof. A pressure accumulation communication passage 76 communicating with the dynamic pressure accumulation chamber 28 and the shutoff valve return urging chamber 73 is opened. The spool 72 is formed with a hollow hole 77 extending upward from the lower end surface thereof, and the peripheral wall of the spool 72 is a communication hole extending from the intermediate height thereof to the peripheral surface and constantly communicating with the internal inlet / outlet passage 74.
78, a pump valve hole 79 extending from its lower portion to the peripheral surface and communicating with the pump communication passage 75 when the spool 72 is located below the top dead center, and extending from the upper end portion to the peripheral surface, Accumulation passage when spool 72 is located at top dead center and bottom dead center
An accumulator valve hole 80 communicating with 76 is formed.

The pressure-accumulation fuel injector 29 includes an injection pipe 84 fitted inside the other side of the body 83, and a valve closing pressurizing fuel chamber 85 and a first pressure accumulation chamber 96 are vertically arranged in a lower half portion of the injection pipe 84. Injection pipe formed in series
One or more (two in this case) injection holes 87 are formed at the lower end of 84. The injection valve 88 that closes the connection between the first pressure accumulating chamber 96 and the injection hole 87 in the vicinity of the injection hole 87 is a needle valve, and the upper end of the valve shaft 89 is formed in the upper half of the injection pipe 84. The valve closing spring chamber 90 is made to plunge. Valve closing spring chamber 90
A valve-closing spring 91 for urging the injection valve 88 to be closed is housed in the valve. An adjusting nut 92 for adjusting the urging force of the valve-closing spring 91 is screwed to the upper end of the injection pipe 84 in an oil-tight manner. Covered by cover nut 93. The inner space 94 of the cover nut 93 is a valve closing spring chamber.
It communicates with 90, and together with this, constitutes a pressure accumulation chamber 28 for shut-off valve return. The valve closing pressurization fuel chamber 85 and the first pressure accumulation chamber 96 are partitioned by a check valve 95. The check valve 95 includes a valve seat 100 formed by enlarging a part of a valve shaft 89, an annular valve body 101 that comes in contact with and separates from a temporary surface of the valve seat 101, and a valve closing spring 102 that urges and closes the valve.
Consists of. Around the middle height of the injection pipe 84, an annular second pressure accumulation chamber 97 partitioned by this and the body 83 is provided. This second pressure accumulation chamber 97 is located on the opposite side of the fuel injection pump 26. The second pressure accumulation chamber check valve 98 and the second pressure accumulation chamber pressure accumulation setting valve 99 arranged inside the body 83 are connected to the first pressure accumulation chamber 96, and together with the first pressure accumulation chamber 96 form the injected fuel pressure accumulation chamber 86. ing. The first pressure accumulating chamber 96 has a relatively small volume,
The second pressure accumulation chamber 97 has a relatively large volume.

The discharge passage 11 is configured so that it can be shut off by an emergency stop solenoid valve 13 immediately before the metering device 14, and
The outlet passage 49 can be closed by the manual stop valve 15.

Next, the operation of this fuel system will be described.

As shown in Fig. 12 (1), in the initial state, the plunger
81 is located at the top dead center, and the spool 72 is located at the bottom dead center. Further, the internal pressures of the shutoff valve return pressure accumulation chamber 28, the pump return pressure accumulation chamber 27, the shutoff valve return biasing chamber 73, and the pump chamber 82 are reference pressures adjusted by the pressure adjusting device 12. Here, time point a in FIGS. 13 (1) to 13 (6) [hereinafter, simply referred to as time point a]. 13 (1) to 13 (6) is the same as the above), the supply timing determining groove portion 58b of the supply timing determining valve 18 and the inlet / outlet passage 24 are communicated with each other from time b to time b. The pressurized fuel Vin is press-fitted into the unit injector 4. First, this fuel Vin is shown in Fig. 12 (2).
As shown in FIG. 7, the spool 72 is pressed into the pump return pressure accumulating chamber 27, and the spool 72 is pushed up from the bottom dead center to the intermediate height. When the plunger 81 is lowered by the drive device 5 from the time point c after this, the internal pressures of the pump chamber 82, the pump return pressure accumulation chamber 27, the shutoff valve return biasing chamber 73, and the shutoff valve return pressure accumulation chamber 28 gradually increase. Ascend, and as shown in FIG. 12 (3), the pump chamber 82
When the amount of fuel equal to the maximum injection amount Vmax is injected into the pump return pressure accumulating chamber 27 from, that is, the amount of fuel pushed out from the pump chamber 82 in the remaining stroke of the plunger 81 becomes equal to the injected fuel Vin. When spool 72
Is raised to top dead center. Since the check valve 95 of the fuel injector 29 is closed during the downward stroke of the plunger 81 from the time point c to the time point d when the spool 72 reaches the top dead center, the fuel is not injected into the fuel injector 29. Called invalid stroke. When the spool 72 reaches the top dead center, the internal pressure of the pump chamber 82 reaches the valve opening pressure of the check valve 95 and the pump communication passage
75 and the pump valve hole 79 are shut off. Further, the pressure accumulation valve hole 80 is communicated with the pressure accumulation communication passage 76, and the internal pressure of the pump return pressure accumulation chamber 27 is corrected so as to match the internal pressures of the shutoff valve return accumulation chamber 28 and the shutoff valve return biasing chamber 73. . After this time point d, the fuel Vin is injected into the injected fuel pressure accumulating chamber 86 as the plunger 81 descends and the internal pressure of the pump chamber 82 further increases. The fuel injected into the injected fuel pressure accumulating chamber 86 is exclusively pressed into the first pressure accumulating chamber 96 until the pressure e reaches the internal pressure of the second pressure accumulating chamber 97, and the pressure exceeds the internal pressure of the second pressure accumulating chamber 97. Then, the check valve 98 for the second pressure accumulating chamber is opened and pressed into the second pressure accumulating chamber 97. Plunger 81 as shown in Fig. 12 (4)
At time f when the bottom dead center is reached, the fuel pressure stops increasing, the check valve 95 is closed, and the fuel Vin is injected into the injected fuel pressure accumulating chamber 86.
Is stored at high pressure. Then, at a predetermined time point g thereafter, the inlet / outlet passage 24 has the pressure relief valve body passage 59 and the advance valve body passage 62.
And the depressurized fuel breathing chamber 21 through the breathing passage 70,
The internal pressure of the access passage 24 starts to be reduced. The timing for starting the pressure reduction is set by the pressure relief valve body passage 59 communicating with the advance valve body passage 62 communicating with the inlet / outlet passage 24, and therefore is standard when the engine speed is high. It becomes faster than the normal timing, and becomes slower than the standard timing when the engine speed is slow.

That is, when the engine speed increases, the internal pressure of the advance pressure receiving chamber 63 increases in direct proportion to the engine speed, the advance valve body 61 moves in the advance direction, and the main shaft 7 is rotated at the best rotation side. The pressure relief valve body passage 59 and the advance valve body passage 62 communicate with each other, so that the center pressure relief valve body passage 59 and the advance valve body passage 62 are provided.
The inlet / outlet passage 24 is faster than the valve passage for pressure release
It is communicated with the advance valve body passage 62 via 59, so that the injection timing can be advanced. Further, when the engine speed decreases, the pressure relief valve body passage 59 on the rotation lower side of the main shaft 7 and the advance valve body passage 62 communicate with each other, thereby advancing to the center pressure relief valve body passage 59. The inlet / outlet passage 24 is communicated with the advance valve body passage 62 via the pressure release valve body passage 59 later than the case where the angle valve passage 62 is communicated, and the injection timing is delayed. At an intermediate speed, the central pressure relief valve body passage 59 and the advance valve body passage 62 communicate with each other, and the exit passage 24 is opened at a standard timing.
Is communicated with the advance valve body passage 62 through the pressure relief valve body passage 59, and the pressure relief for injection is performed at standard timing.
The advance valve body passage 62 not only selectively communicates with the respective pressure relief valve body passages 59, but also in the transitional region corresponding to the pressure relief valve body passages 59, the center and the uppermost pressure relief valve body passages. 59 or two pressure release valve body passages 59 in the center and the lowermost pressure release valve body passage 59 can be communicated at the same time. Depending on the ratio of the connection area with both pressure release valve body passages 59, the rise characteristics of the pressure release Is changing. In this manner, the position of the advance valve body 61 can be easily and highly accurately controlled depending on the pressure adjusting characteristic of the pressure adjusting device 12 with respect to the engine rotation speed, so that the advance angle can be easily and accurately controlled. become.

The spool 72 gradually descends from the top dead center and the pump valve hole 79
From the time point h when the communication between the pump communication passage 75 and the pump communication passage 75 is restored, the internal pressure of the valve closing pressurization fuel chamber 85 sharply decreases and the internal pressure of the valve closing pressurization fuel chamber 85 drops to a predetermined valve opening pressure from the time point i. Check valve
The differential pressure acting on 95 overcomes the urging force of the valve closing spring 91 to open the injection valve 88.

As described above, when the spool 72 reaches the top dead center, the pressure accumulation valve hole 80 and the pressure accumulation communication passage 76 communicate with each other, so that the injector 29
When the fuel is injected into the
The rise in the internal pressure of the pump return pressure accumulator chamber 27 caused by the leak fuel to the pump is corrected, and the timing at which the pump communication passage 75 and the pump valve hole 79 communicate with each other at the time of depressurization is prevented from being delayed. Then, the occurrence of an injection timing error (delay) due to this communication delay is prevented.

Here, the pump communication passage 75 is composed of a small-diameter pump communication passage 75a and a large-diameter pump communication passage 75b which are vertically arranged, and the spool 72
Starts to descend from the top dead center and the small-diameter pump communication passage 75a communicates with the pump valve hole 79 first, so that the decrease in the internal pressure of the valve closing pressurization fuel chamber 85 is suppressed relatively slowly, and the valve opening amount of the injection valve 88 is reduced. Is suppressed to a small amount and the amount of fuel injection is suppressed to a small amount, and the reduction of the internal pressure of the injected fuel pressure accumulating chamber 86 due to the fuel injection is suppressed to be small. Then, when the spool 72 further descends and reaches, for example, a time point j corresponding to the ignition time point at the rated rotation speed, the large diameter pump communication passage 75b communicates with the pump valve hole 79, and the valve closing pressurization fuel chamber is suddenly opened. The internal pressure of 85 is reduced, the injection valve 88 is suddenly and largely opened, and a large amount of fuel is vigorously injected at high pressure. In this way, by suppressing the fuel injection amount before ignition to a small amount, it is possible to reduce the explosion sound at the time of ignition and prevent operating noise. Further, by injecting a large amount of fuel at a high pressure after ignition, it is possible to obtain the maximum thermal efficiency as long as it is allowed to reduce the operating noise. Further, since the injection pressure is a high pressure inside the injected fuel pressure accumulating chamber 86, it is possible to inject a predetermined amount of fuel Vin in a short time. Then, after the time point k when the internal pressure of the injected fuel pressure accumulating chamber 86 becomes equal to or lower than the setting pressure of the pressure accumulating setting valve 99 for the second pressure accumulating chamber, the pressure accumulating setting valve 99 is closed and the internal pressure of the second pressure accumulating chamber 97 is set to that value. Hold on to pressure. On the other hand, the volume of the injected fuel pressure accumulating chamber 86 communicating with the injection hole 87 is substantially reduced to that of the first pressure accumulating chamber 96, and even if a small amount of fuel is injected, the internal pressure of the first pressure accumulating chamber 96 is reduced. Then, the internal pressure is reduced to a predetermined valve closing pressure in a short time, and the injection valve 88 is closed (at a time point 1). Therefore, the injection time can be greatly shortened, which is advantageous in increasing the engine speed. After the fuel injection is finished,
At a predetermined time point m, the cam lift of the fuel injection cam 30 of the drive unit 5 starts to decrease, and the internal pressure of the pump chamber 82 causes the plunger 81 to rise while being pressed against the rocker arm 33 of the drive unit 5. As the plunger 81 rises, the volume of the pump chamber 82 increases, and the internal pressures of the pump chamber 82 and the pump return pressure accumulating chamber 27 are reduced, so that the spool 72 is lowered by the pressure of the shutoff valve return urging chamber 73. Then, the fuel is pushed into the pump chamber 82 from the pump return pressure accumulation chamber 27 until the amount of fuel equal to the maximum injection amount Vmax is injected from the pump return pressure accumulation chamber 27 into the pump chamber 82.

By the way, during the depressurization period after the time point g, fuel escapes from the pump return pressure accumulating chamber 27 to the depressurized fuel breathing chamber 21 side. Therefore, if the spool 72 is lowered to the bottom dead center as it is, the timing control composite is performed. The amount of fuel filled from the valve device 3 to the unit injector 4 side becomes smaller than in the initial state, and when the pressure-adjusted / metered fuel is next pressed into the unit injector 4, the spool 72 corresponds to the press-fitted amount. As a result, the vehicle only rises to a position lower than the height to be raised, which causes operational noise and injection timing control errors, and also causes a shortage of the next fuel injection amount.

Therefore, at time n when the spool 72 descends to the vicinity of the bottom dead center, the pressure-release fuel breathing chamber 21 has the breathing passage 70 and the pressure-release fuel returning passage.
The discharge return urging means 69 is communicated with the entrance / exit passage 24 via 22.
The fuel that has been pushed into the depressurized fuel breathing chamber 21 for depressurization is discharged back into the inlet / outlet passage 24, and further discharged into the pump return pressure accumulating chamber 27 and the pump chamber 82. By discharging the fuel thus sucked back to the unit injector 4, a fuel shortage at the next injection is prevented. However, since the fuel contained in the depressurized fuel breathing chamber 21 is higher than the initial pressure, the internal pressure of the pump return pressure accumulating chamber 27 and the pump chamber 82 becomes higher than the initial state, and the spool 72 is lowered. It is moved to the top dead center side from the vicinity of the dead center. Therefore, in order to return from this state to the initial state, the initial pressure supply passage 23 is finally communicated with the inlet / outlet passage 24 at the predetermined time point o, and the shut-off valve return pressure accumulation chamber 28,
The internal pressures of the pump return pressure accumulation chamber 27, the shutoff valve return biasing chamber 73, and the pump chamber 82 are returned to the reference pressure adjusted by the pressure adjusting device 12, and the spool 72 is returned to the bottom dead center.

By the way, the internal pressures of the shut-off valve return accumulator chamber 28 and the shut-off valve return energizing chamber 73 are increased due to fuel leakage from the second accumulator chamber 97, or due to leaks to the pump return accumulator chamber 27 during depressurization. It may be decompressed. If the internal pressures of the shutoff valve return pressure accumulating chamber 28 and the shutoff valve return biasing chamber 73 increase, the spool is driven by the internal pressure of the shutoff valve returning pressure accumulating chamber 28 when fuel is injected from the metering supply device 2 next time. The rise of 72 is hindered, and the pressure accumulation volume of the pump return pressure accumulation chamber 27 is narrowed. As a result, after the fuel is press-fitted into the injector 29, when the plunger 81 rises, the pump return pressure accumulating chamber 27 to the pump chamber 82
Since the amount of fuel injected into the cylinder is insufficient, the plunger 81 cannot rise to the top dead center, resulting in operating noise. Further, if the internal pressures of the shutoff valve return accumulator chamber 28 and the shutoff valve return biasing chamber 73 are reduced, fuel is injected from the metering supply device 2 next time, and when the plunger 81 is lowered, the pump communication passage 75 and The timing at which the pump valve hole 79 is shut off is delayed, and the fuel injection amount is reduced.

Here, when the spool 72 is returned to the bottom dead center,
80 again communicates with the pressure accumulation communication passage 76, and the pressure accumulation chamber 28 for shut-off valve return movement
Since the internal pressure of the shut-off valve return urging chamber 73 is corrected to the reference pressure (initial pressure), the generation of operating noise due to the increase of these internal pressures and the occurrence of the injection amount error (decrease) due to the pressure reduction are prevented. It will be done.

Although the injection fuel breathing chamber 21 is provided here so as not to release the depressurized fuel to the outside, the injection fuel breathing chamber 21
It is not essential to the present invention to provide the initial pressure supply passage 23, which is communicated with the pressure adjusting device 12 via the advance pressure receiving chamber 63, to the inlet / outlet passage 24 of the valve box 56 without the provision thereof. Even if it is just timed communication, from the pressure regulating device 12 to the advance pressure receiving chamber 63,
A pump return pressure accumulator chamber 27, a pump chamber 82, and a valve closing pressurization accumulator chamber 85 through the initial pressure supply passage 23, the inlet / outlet passage 24, and the shutoff valve 25.
It is possible to restore the initial state by refueling the.

<Effects of the Invention> As described above, according to the pressure-accumulation type fuel injection device for a diesel engine according to the present invention, the advancement device has the valve element of the injection timing determination pressure relief valve having the injection timing determination pressure relief passage, An advance valve body having an advance valve body passage, a retard urging means for urging the advance valve body in the retard direction, and an advance mechanism for urging the advance valve body toward the advance side. Since it is configured as one valve together with the angle pressure receiving chamber, the configuration of the advance device can be simplified. Moreover, since the mechanism for determining the injection timing and the advance device for adjusting the injection timing are incorporated in the fuel injection device, the fuel injection device can be generalized regardless of the size of the engine or the like. Further, since the operation principle and the configuration of the advance angle device are simple, the failure is less likely to occur and the reliability is high. Further, fuel commensurate with the fuel to be released for pressure relief at the time of injection is replenished from the pressure regulator to the inlet of the injection timing setting pressure relief valve through the advance pressure receiving chamber and the initial pressure supply passage, and the fuel injector, Since the fuel injection pump and the pump return pressure accumulating chamber are reliably returned to the initial state, the plunger is surely raised to the top dead center, and between the parts of the drive device for driving the fuel injection pump or between the drive device and the plunger. It is possible to prevent the occurrence of gaps in the engine, to prevent operating noise due to impact between drive parts or between the drive and the plunger, and to prevent error in injection timing control due to vibration of drive device parts. It is possible to prevent insufficient injection amount during injection. In addition, the mechanism for returning the fuel injector, the fuel injection pump, and the pump return pressure accumulating chamber to the initial state is simply connected to the advancing valve body from the advancing pressure receiving chamber to the depressurizing valve passage. It is simple because it only needs to form the initial pressure supply path.

[Brief description of drawings]

FIG. 1 is an equivalent circuit diagram showing an entire configuration of a pressure-accumulation type fuel injection device for a diesel engine according to an embodiment of the present invention.
FIG. 3 is a vertical sectional side view of the fuel metering supply device and the timing control combined valve device, FIG. 3 is a vertical sectional front view of the transfer pump, FIG. 4 is a vertical sectional front view of the pressure regulating device, and FIG. FIG. 6 is a vertical sectional front view of the timing control combined valve device, FIG. 7 is a vertical sectional front view of the timing control combined valve device, FIG. 8 is a perspective view of the common valve body thereof, and FIG. The figure is a partial cutaway perspective view of the valve for adjusting the advance angle,
FIG. 10 shows each valve body passage formed on the peripheral surface of the common valve body,
Fig. 11 is a development view showing the arrangement of the depressurized fuel return passage and the initial pressure supply passage. Fig. 11 is a vertical sectional view of the unit injector.
12 (1) to 12 (4) are schematic diagrams showing the operation of the pump return pressure accumulating chamber in sequence, and FIGS. 13 (1) to 13 (6) are schematic diagrams of respective portions of the unit injector. Timing diagrams showing the relationship between the operation timing, the pressure change and the operation timing of the timing control combined valve device, FIG. 14 is a configuration diagram of a conventional fuel injection device and an advance angle device, and FIG. 15 is a pressure accumulation type of a conventional diesel engine FIG. 16 is an equivalent circuit diagram showing the entire configuration of the fuel injection device, FIG. 16 is an equivalent circuit diagram of the pressure accumulation type fuel injection device according to the prior invention, and FIG. 17 is an equivalent circuit diagram of the pressure accumulation type fuel injection device according to the second prior invention. is there. 1 ... Fuel tank, 12 ... Pressure adjusting device, 14 ... Metering device (metering supply device), 19 ... Injection timing determination pressure relief valve, 20 ...
… Advance valve for adjusting injection timing, 21 …… Depressurized fuel breathing chamber, 23…
… Initial pressure supply passage, 24 …… Inlet / outlet passage (inlet), 25 …… Composite shut-off valve (shut-off valve), 26 …… Fuel injection pump, 27 …… Pump return accumulator, 29 …… Accumulator fuel injection Vessel, 56 …… Valve box, 57 …… Pressure release valve body, 59 …… Pressure release valve body passageway, 60 ……
Advance valve chamber, 61 ... Advance valve body, 62 ... Advance valve passage (advance passage), 63 ... Advance pressure receiving chamber, 65 ... Delay biasing means, 85 ...... Accumulation chamber for valve closing pressurization, C ...... Crankshaft.

Claims (1)

[Claims] 1. A pressure-accumulation fuel injector for a fuel tank (1) of a diesel engine via a pressure regulator (12), a metering device (14), a shutoff valve (25), and a fuel injection pump (26). (2
9), the fuel injection pump (26) communicates with the pump return pressure accumulator chamber (27) through the cutoff valve (25), and the pressure regulator (12) corresponds to the engine speed. In a pressure-accumulation fuel injection device for a diesel engine configured to increase the supply pressure, a fuel injection pump (26) and a shutoff valve (25) are provided in a fuel chamber (85) for pressurizing a valve of a fuel injector (29). The injection timing setting pressure relief valve (19) and the injection timing adjustment advance valve (20) were connected in this order, and the pressure relief valve (19) was connected to the inlet (2) formed in the valve box (56).
4), the pressure relief valve body passage (5) formed in the pressure relief valve body (57).
9) is configured to be communicated intermittently, and the valve element (57) for pressure release is time-interlocked with the crankshaft (C), and the advance valve (20) is a valve passage ( 62) is selectively connected to a plurality of pressure relief valve body passageways (59), and each of the plurality of pressure relief valve body passageways (59) is connected to the rotation direction of the pressure relief valve body (57) and The advance valve body passage (62) is formed so as to run in the circumferential direction on the circumferential surface of the advance valve body (61), and the advance valve body (61) is The valve body (57) for depressurization is slidably fitted into the valve chamber (60) for advancing formed along the axial direction of the valve body (57) for retarding the valve body (61) for advancing. The biasing means (65) biases the retarding side and the fuel pressure of the advancing chamber (63) biases the advancing side, and the advancing chamber (63) is adjusted as described above. Communicate with the pressure device (12), and from the pressure relief valve body passage (59) to the pressure relief valve body (57). An upright initial pressure supply passage (23) is formed, a starting end portion of the initial pressure supply passage (23) is communicated with the advance angle pressure receiving chamber (63), and an end portion thereof is connected to the injection timing setting pressure relief valve ( A pressure-accumulation fuel injection device for a diesel engine, which is configured so that it can intermittently communicate with the introduction port (24) of 19).