JPS63134851A - Accumulator fuel injection device for diesel engine - Google Patents

Abstract

PURPOSE:To make the wide use of a fuel injection device possible independently of the size of an engine or the like by assembling both an injection time determining mechanism and an injection time adjusting spark advance device in the fuel injection device. CONSTITUTION:A pressure relief valve 19 for determining injection time and a spark advance valve 20 for adjusting injection time are connected in order to the valve closing pressure accumulating chamber 85 of a fuel injector 29 through a fuel injection pump 26 and a cutoff valve 25. A pressure relief valve 19 is composed so that passages 59 for a pressure relief valve body 57 may communicate with the introducing port 24 of a valve box 56 with timing control made on a crankshaft. A spark advance valve 20 is composed so that the passages 59 may be plurally provided along the rotational direction of the valve body 57, and moreover the passage 62 for spark advance of a spark advance valve body 61 may selectively communicate with the plural passages 59. In addition to that, the spark advance valve body 61 is energized by a spark regress energizing means 65 to the side of spark regress, and by fuel pressure in a spark advance pressure chamber 63 communicating with pressure regulating device 12 to the side of spark advance.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a pressure accumulation type fuel injection device for a diesel engine, and in particular, the advance angle device can be simplified, and the advance angle device can be incorporated into the fuel supply device. In addition to increasing versatility, the mechanism of the advance angle device is simplified to improve reliability, and it also reduces the occurrence of operational noise, errors in injection timing, and insufficient injection amount the next time due to pressure relief for fuel injection. The present invention relates to a pressure accumulation type fuel injection device for a diesel engine that can prevent the above problems and also simplify the mechanism for returning the injector, fuel injection pump, pump double-acting pressure accumulation chamber, etc. to the initial state.

The present invention, as shown in FIG. death,
A pressure accumulation type fuel injection device for a diesel engine, in which a fuel injection pump 26 is connected to a pressure accumulation chamber 27 for double-acting pump via a cutoff valve, and a pressure regulation device 12 is configured to increase fuel supply pressure in accordance with the rotational speed of the engine. It was invented on the premise that Here, the pressure accumulation type fuel injector 29 refers to the first
As illustrated in FIG. 1, after the fuel is injected into the injection fuel pressure accumulation chamber 86 through the valve-closing pressurizing fuel chamber 85 and the check valve 95, the internal pressure of the valve-closing pressurizing fuel chamber 85 is reduced, and the injector When the internal pressure of the valve-closing pressurizing fuel chamber 85 of No. 29 falls below a predetermined value, the internal pressure of the injected fuel accumulating chamber 86 overcomes the valve-closing force of the valve-closing spring 91 and the internal pressure of the valve-closing pressurizing fuel chamber 85, and the injection valve 88 This is an injector in which the valve is opened and the fuel in the injected fuel pressure accumulation chamber 86 is injected from the injection hole 87. The valve closing pressurization fuel chamber 85 is normally communicated with the pump chamber 82 of the fuel injection pump 26 .

<Prior art> Conventionally, the internal pressure of this valve closing pressurizing fuel chamber 85 is equal to that of the pump chamber 8.
After the check valve 95 is opened from 2 to pressurize the fuel into the injection fuel pressure storage chamber 86, the pressure is reduced by raising the plunger 81. As shown in FIG. 14, the plunger 81 is raised directly by the fuel injection cam 30 of the drive device 5 linked to the crankshaft (shown in FIG. 2), or by the cam follower 31, push rod 32, or rocker arm. 33 etc. Further, the cam follower 31 is eccentrically supported by an eccentric shaft 106 for advance angle which is rotatably supported by a wall portion 105 of the engine, and the eccentric shaft 106 is moved toward an advance angle or a retard angle depending on the rotational speed of the engine. By rotating the cam follower 31 toward the side, the contact position between the cam follower 31 and the fuel injection cam 3o is changed, thereby adjusting the fuel injection timing.

<Prior Invention> In the conventional pressure accumulation type fuel injection device for a diesel engine configured as described above, the plunger 81 does not rise to top dead center during partial load, resulting in operational noise and difficulty in determining injection timing with high precision. The problem was that it was difficult to do so.

Therefore, in order to solve such problems, the inventor of the present invention, prior to the present invention, installed a fuel tank 1 of a diesel engine with a pressure regulating device 12 and a metering device 14, as shown in FIG.
, a pressure accumulation type fuel injection device for a diesel engine, which is connected to a pressure accumulation type fuel injector 29 via a cutoff valve 25 and a fuel injection pump 26, and is connected to a pressure accumulation chamber 27 for reciprocating pump operation to the fuel injection pump 26 via a cutoff valve. invented.

According to this prior invention, the fuel accumulated in the pump reciprocating pressure accumulation chamber 27 during the downward stroke of the plunger 81 is transferred to the pump chamber 81 during the upward stroke of the plunger 81.
Since the plunger 81 is press-fitted into 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 this drive value W5
The problem is that the structure, shape and dimensions of the parts are different depending on the size of the engine, and it lacks versatility. Another problem is that the advance angle device is built into the drive device 5, and its versatility is also poor.

Therefore, prior to the present invention, as shown in FIG. 1, the present inventor invented an accumulator fuel injection system for a diesel engine having the configuration of the prior invention described above, which was improved as follows.

That is, the pressure regulating device 12 is configured to increase the fuel supply pressure in accordance with the rotational speed of the engine, and the fuel injection pump 26 and the cutoff valve 25 are connected to the fuel chamber 85 for pressurizing the valve of the fuel injector 29.
The pressure relief valve 19 for determining the injection timing and the advance valve 20 for adjusting the injection timing are connected in sequence through the pressure relief valve 19 and the pressure relief valve 5 to the inlet 24 of the valve box 56
The advance valve 20 is configured to connect the pressure relief valve body passage 59 of No. 7 to the crankshaft C in timing communication, and the advance valve 20 connects the pressure relief valve body passage 59 along the rotational direction of the pressure relief valve body 57. A plurality of advance valve bodies 61 are provided, and the advance passages 62 of the advance valve bodies 61 are selectively communicated with the advance valve bodies 61 through the advance valve body passages 59 . The pressure receiving chamber 63 is configured to be biased toward the retard side and biased toward the advance side by the fuel pressure in the advance pressure receiving chamber 63.
invented an accumulator fuel injection system for diesel engines that communicates with

According to this improved prior invention, after fuel is pressurized into the injector 29, the injection valve 88 is opened by opening the pressure relief valve 19 and reducing the internal pressure of the pressure accumulation chamber 85 for valve closing pressurization. Ru. Therefore, the injection timing is determined with high precision by the timing when the injection timing determining 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.

In addition, since the position of the advance valve body 61 is determined depending on the internal pressure of the advance pressure receiving chamber 63, which increases the fuel supply pressure according to the rotational speed of the engine by the pressure regulator 12, the injection timing can be adjusted. The mechanism of the advance angle device can be simplified. Further, since the pressure relief valve 19 and the advance valve 20 are incorporated into the fuel supply system, it can be used for general purposes regardless of the engine size.

<Problems to be Solved by the Invention> However, according to the above-mentioned improved prior invention, since fuel is released from the valve-closing pressurizing fuel chamber 85 during fuel injection, the pump chamber 82 and the pump return valve communicating with the valve-closing pressurizing fuel chamber 85 are The fuel in the dynamic pressure accumulator 27 becomes less than the initial state, and the plunger 81 cannot return to the top dead center during the upward stroke of the plunger 81 (as a result, damage occurs between each component of the drive device 5 or between the drive device 5 and the plunger 81 There is a gap between the fuel and the fuel, which causes operational noise.The next time fuel is injected into the injector 29, less fuel is injected than the metered amount.
It was also found that problems such as insufficient injection amount occurred.

The present invention has been made in consideration of the above circumstances, and it is possible to simplify the mechanism of the advance angle device, increase the versatility of the fuel injection device by equipping it with an advance device, and The mechanism of the advance device that adjusts the timing has been simplified to improve reliability, and the injector, fuel injection pump, pump return pressure accumulator, etc. can be returned to the initial state reliably after fuel injection. It is an object of the present invention to provide a pressure accumulation type fuel injection device for a diesel engine which can simplify a mechanism for returning to the state.

Means for Solving the Problems> In the present invention, the following technical measures are taken in order to achieve the above object in a pressure accumulation type fuel injection device for a diesel engine having the above-mentioned prerequisite configuration.

That is, as shown in FIG.
The pressure relief valve 19 for determining the injection timing and the advance valve 20 for adjusting the injection timing are connected in order through the pressure relief valve 19 for determining the injection timing. The injection timing adjustment advance valve 20 is configured to communicate with the pressure relief valve body passage 59 in a timed manner.
A plurality of valve bodies for pressure relief are provided along the rotational direction of the valve body for pressure relief, and an advance valve body passage 62 is configured to be selectively communicated across the plurality of valve body passages 59 for pressure relief. The body 61 is biased toward the retard side by the retard biasing means 65 and biased toward the advance side by the fuel pressure in the advance pressure chamber 63, and the advance pressure chamber 63 is biased toward the advance side by the fuel pressure in the advance pressure chamber 63. A pressure relief valve body passage 59 is connected to the pressure device 12 and the pressure relief valve body 57 is connected to the pressure relief device 12 .
An initial pressure supply passage 23 is formed independent of the initial pressure supply passage 23, and the starting end of the initial pressure supply passage 23 is communicated with the advance pressure receiving chamber 63, and the terminal end thereof is connected to the introduction port 24 of the injection timing determining pressure relief valve 19. It is configured to enable timed communication.

<Operation of the Invention> According to the pressure accumulation type injection device for a diesel engine of the present invention, the 3Ul determining body valve passage 59 at the time of injection of the pressure relief valve 19 for determining the injection timing selected by the advance valve 20 is connected to the crankshaft C.
When the fuel chamber 85 for valve closing pressurization is communicated with the inlet port 24 of the valve box 56 at the same time, the fuel in the valve closing pressurizing fuel chamber 85 is released to the outside from the pressure relief valve 19, the internal pressure of the valve closing pressurizing chamber 85 is reduced, and the fuel is injected. The valve 88 is opened and fuel is injected from the injection hole 87. This injection timing is adjusted depending on which pressure release valve body passage 59 the advance 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 depends on the position of the advance valve body 61 where the retardation biasing means 65 and the fuel pressure in the advance pressure receiving chamber 63 are balanced. determined by Since the advance pressure receiving chamber 63 receives fuel from the pressure regulator 12 that is configured to increase the fuel supply pressure in accordance with the rotational speed of the engine, the position of the advance valve body 61 is adjusted according to the rotational speed of the engine. It will be moved to the advance angle side in accordance with the speed.

Further, after the fuel injection is completed, the valve closing pressurization fuel chamber 85, the fuel injection pump 26, and the pump reciprocating pressure accumulation chamber 27 are connected to the pressure regulating device 12 via the initial pressure supply path 23 and the advance pressure receiving chamber 63. Since the valve-closing pressurization fuel chamber 85, the fuel injection pump 26, and the pump double-acting pressure accumulation chamber 27 are refilled with the fuel that escaped during injection from the pressure regulator 12, their internal pressures are reliably returned to their initial states. It will be.

<Example> Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, this diesel engine fuel system measures the amount of fuel in a fuel tank 1 according to the load conditions of the engine using a metering supply device 2, and controls the timing control compound valve device 3 to determine when the fuel is supplied. The fuel is supplied to the unit injector 4 at a predetermined timing via the determining valve 1, and after being pressurized into the accumulating fuel injector 29 by driving the fuel injection pump 26 with the drive device 5, the fuel is injected by the timing control compound valve device 3. Time! The fuel in the fuel chamber 85 for valve closing pressurization of the pressure accumulation type fuel injector 29 is released to the pressure relief fuel breathing chamber 21 by the pressure relief valve 19 for setting IIl and the advance valve 20 for adjusting 'M at the time of injection to the fuel chamber 85 for valve closing pressurization of the pressure accumulation type fuel injector 29. This reduces the internal pressure of the injection valve 88.
The valve is opened to inject fuel from the injection fuel accumulation chamber 86 through the injection hole 87, and at a predetermined timing after the injection ends,
The fuel in the depressurized fuel breathing chamber 21 is discharged back to the unit injector 4 via the depressurized fuel return passage 22, and the fuel reduced by the depressurization is returned to the unit injector 4. The unit injector 4 is returned to its initial state by communicating the initial pressure supply path 23 with the unit injector 4.

As shown in FIG. 2, the III quantity supply device 2 includes a transfer pump 10, a pressure regulating device 12 (FIG. 4), a metering device 14, and a pressure pump 16, which are built into a thick cylindrical casing 6. A fuel pipe (not shown) and an inlet joint 8 (fourth
) and the inlet passage 9' (Fig. 4), and the pressure of the fuel discharged from the transfer pump 10 is adjusted by the pressure regulator 12 to correspond to (for example, directly proportional to) the rotational speed of the engine. The metering device 14 measures the fuel whose pressure has been adjusted according to the load condition of the engine, and adjusts the pressure.
The metered fuel is configured to be pressure-fed to the timing control compound valve device 3 by a pressure-feeding pump 16.

The transfer pump 10 has a pump chamber 34 formed at the front end of the casing 6, and inside this pump chamber 34,
As shown in FIG. 3, an inner rotor 35 fixed to the main shaft 7 passing through the casing 6 and an outer rotor 36 eccentrically meshed with the inner rotor 35 are inserted, and fuel is supplied from the inlet passage 9 through the suction port 37° to both sides. It is sucked in between the rotors 35 and 36 and discharged from the discharge port 38 into the discharge passage 11.

As shown in FIG. 4, the pressure regulating device 12 includes a pressure regulating plug 3 that is branch-connected to the discharge passage 11 and screwed onto the casing 6.
9, a pressure regulating valve body 40 slidably fitted therein, and a valve closing spring 41 biasing the pressure regulating valve body 40 to the valve closing position. A pressure regulating valve hole 42 is opened in the peripheral wall of the pressure regulating plug 39, and this pressure regulating valve hole 42 communicates with the inlet passage 9. The discharge pressure of the transfer pump 10 changes quadratically in response to the rotational speed of the engine, and in response to this discharge pressure, the pressure regulating valve body 40 is biased in the valve opening direction against the valve closing spring 41. be done. In this pressure regulating device 12, by appropriately setting the opening area of the pressure regulating valve hole 42 with respect to the amount of displacement of the pressure regulating valve body 40 from the valve closing position, the pressure regulating device 12 is connected to the inlet passage 9 in response to the rotational speed of the engine. The internal pressure of the discharge passage 11 is increased or decreased in exact proportion to the rotational speed of the engine. However, the correspondence between the internal pressure of the discharge passage 11 controlled by the pressure regulator 12 and the rotational speed of the engine is not limited to being directly proportional; for example, the higher the speed, the more the discharge passage 11
The rate of increase in the internal pressure of the discharge passage 11 may be configured to decrease, or conversely, the rate of increase in the internal pressure of the discharge passage 11 may be configured to increase as the speed increases. In addition, for the three pressure regulating plugs mentioned above,
A drain vibe joint 43 for connecting a drain vibe (not shown) for discharging leaked fuel from between this and the pressure regulating valve body 42 is connected.

As shown in FIG. 2, the metering device 14 includes a 31-piston 44 fitted into the front half of the main shaft 7 so as to be movable forward and backward. This metering piston 44 is moved by the governor spring 4 by the thrust of the flyway toy 5 in accordance with the rotational speed of the engine.
6 in the direction of fuel reduction (in this case, forward). A metering valve hole 47 that communicates with the discharge passage 11 is opened in the inner circumferential surface of the main shaft 7, and a metering valve body passage 48 is recessed in the circumferential surface of the 1ift piston 44 over its entire circumference. ing. By moving the IT]ffi piston 44 forward and backward in response to the rotational speed of the engine, the connection area between the metering valve hole 47 and the metering valve body passage 48 is changed to correspond to the rotational speed of the engine. The flow rate is adjusted accordingly, and the fuel is introduced to the pressure pump 16 through the main shaft 7 and the outlet passage 49 formed in the casing 6.

The pressure of the governor spring 46 is controlled by the speed setting lever 50.
It is now possible to change settings by operating the tS.

As shown in FIGS. 2 and 5, the pressure pump 16 includes a plunger 53 that is driven via a swing arm 52 by a drive cam 51 formed on the circumferential surface of the main shaft 7, and a plunger 53 that moves forward and backward as the plunger 53 moves back and forth. A pump chamber 54 whose volume changes. Further, the pressure pump 16 is configured so that the stroke of the plunger 53 can be changed and set by a torque characteristic setting device 55 to obtain pump characteristics corresponding to various torque characteristics suitable for the application of the engine.

In order to achieve miniaturization and compactness, the timing control compound valve device 3 is incorporated into the metering supply device 2 as shown in FIG. 2 and FIGS. 6 to 8. This timing control composite valve device 3 essentially consists of supply timing determining valves 1 that can be provided independently, as shown in FIG.
8, a pressure relief valve 19 for setting injection timing, an advance valve 20 for adjusting injection timing, and a pressure relief fuel breathing chamber 21 are integrally combined in order to achieve miniaturization and compactness.

That is, as shown in FIGS. 2 and 6 to 8, there is a supply timing determining valve 18 that determines the timing of pumping fuel to each unit injector 4, and a timing determination valve 18 that determines the timing for pumping fuel to each unit injector 4. Pressure relief valve 1 for UI setting
9 is a common valve box 56 consisting of the rear half of the casing 6;
A common valve body 57 formed from the rear half of the main shaft 7 is provided. A pressure feeding passage 17 led out from the pressure pump 16 of the 31RN supply device 2 is opened at the rear end of the inner circumferential surface of the casing 6, and a passage 24 leading in and out to each unit injector 4 (distribution passage) 24 is opened slightly in front of it. The openings are equally spaced in the direction. A communication groove 58a of the supply timing determining valve body passage 58 is recessed in the part of the main shaft 7 facing the pressure feeding passage 17 over the entire circumference. The supply timing determining groove portion 58b is extended in the axial direction along the circumferential surface up to a portion of the outer circumferential surface of the main shaft 7 facing the locus l. Then, the main shaft 7 rotates in conjunction with a crankshaft (not shown), and the supply timing determining groove portion 58b communicates with the inlet/outlet passage 24 by overlapping inside and outside, so that the supply timing determining groove portion 58b communicates with the inlet/outlet passage 24 from the pressure feeding passage 17 via the valve body passage 58 for determining the supply timing. Pressure-regulated and metered fuel is forced into the inlet/outlet passage 24. In addition, a supply timing determining groove portion 58 is provided in a portion of the outer peripheral surface of the main shaft 7 facing the passage locus l of the inlet/outlet passage 24.
At a predetermined timing after time a, the pressure relief valve body passage 59 of the pressure relief valve 19 communicating with the inlet/outlet passage 24 is opened.

The rear half of the main shaft 7, which is the common valve body 57 of the supply timing determining valve 18 and the pressure relief valve 19 for setting the injection timing, also serves as a valve box for the advance valve 20 for adjusting the injection timing. That is,
A cylindrical advance valve chamber 60 is formed concentrically within the rear half of the main shaft 7, and an advance valve body 6 is formed in this advance valve chamber 60.
1 is housed so that it can move forward and backward in the axial direction of the main shaft 7. The valve body 57 includes three pressure relief valve body passages 59 whose opening positions on the inner peripheral surface are different in the rotational direction and the axial direction of the main shaft 7.
is formed so as to pass through its peripheral wall, and the advancing valve body 61
One of the three pressure relief valve body passages 59 is provided on the circumferential surface of the
An advance valve body passage 62 is formed that communicates with one or two adjacent valves. The advancing valve element 1ffl passage 62 is constituted by a circumferential groove recessed over the entire circumference of the advancing valve element 61. The advance valve chamber 60 is divided into an advance pressure receiving chamber 63 and a retard biasing chamber 64 by an advance valve body 61 . and,
The advance pressure receiving chamber 63 is communicated with the discharge passage II whose pressure is regulated by the pressure regulator 12, the retard biasing chamber 64 is communicated with the inlet passage 9 maintained at approximately constant pressure, and the retard biasing chamber 64 accommodates a retard biasing means 65 for biasing the advance valve body 61 in the retard direction.
1 can be controlled with high precision depending on the pressure regulation characteristics with respect to the rotational speed of the engine.

Here, the advance valve body 61 is moved in the axial direction to selectively communicate with the pressure relief valve body passage 59, but the advance angle valve body 61 is moved in the axial direction to selectively communicate with the pressure relief valve body passage 59. It is also possible to configure the valve body 61 to rotate around the axis and selectively communicate with the pressure relief valve body passage 59.

The depressurizing fuel breathing chamber 21 is formed inside the advance valve body 61 in order to achieve miniaturization and compactness. That is, a stepped cylindrical cavity 66 is formed inside the advance valve body 61.
This cavity 66 is formed into a depressurizing fuel breathing chamber 21 and a discharge biasing chamber 6 by a piston 67 slidably fitted inside the cavity 66.
It is divided into 8. The retardation biasing chamber 68 communicates with the inlet passage 9 via the retardation biasing chamber 64, and accommodates a retrieval biasing means 69 therein. The pressure relief fuel breathing chamber 21 is communicated with the advance valve body passage 62 through a breathing passage 70 . When the inlet/outlet passage 24 communicates with the pressure relief fuel breathing chamber 21 via the pressure relief valve body passage 59, the advance valve body passage 62, and the breathing passage 70, the piston 67 is moved by the fuel pressure on the side of the inlet/outlet passage 24. The fuel is pushed into the discharge biasing chamber 68 side, and the fuel is pressurized into the depressurized fuel breathing chamber 21. As a result, the internal pressure of the valve-closing pressurizing fuel chamber 85 of the pressure accumulation type fuel injector 29 communicating with the inlet/outlet passage 24 is reduced, and the injection valve 87 is opened to inject fuel.

A depressurizing fuel return passage 22 is formed in a portion of the peripheral wall of the main shaft 7 facing the passage path l of the inlet/outlet passage 24, and communicates with the inlet/outlet passage 24 at a predetermined timing after the pressure relief valve body passage 59. There is. Then, the depressurized fuel breathing chamber 21 is communicated with the inlet/outlet passage 24 via the breathing passage 70 , the advance valve body passage 62 , and the depressurized fuel return passage 22 , so that the discharge biasing means 69 pushes the piston 67 . The fuel that has been pushed back to the depressurized fuel breathing chamber 21 side and pressurized into the depressurized fuel breathing chamber 21 is discharged back to the injector 4 through the inlet/outlet passage 24.

Further, an initial pressure supply path 23 is recessed in a portion of the peripheral wall of the main shaft 7 facing the passage path i of the inlet/outlet passage 24, and communicates with the inlet/outlet passage 24 at a predetermined timing after the depressurization fuel return passage 22. There is. This initial pressure supply path 23 is connected to the pressure regulating device 1
It communicates with a discharge passage 11 whose pressure is regulated by 2.

As shown in FIGS. 1 and 11, the unit injector 4 includes a compound cutoff valve 25 connected to the inlet/outlet passage 3, a fuel injection pump 26, a pressure accumulation chamber 27 for double-action pump operation, and a pressure accumulation chamber 28 for double-operation cutoff valve. and a pressure accumulator fuel injector 29, the fuel injection pump 26 is built into the body 83 of the injector 29, and the compound cutoff valve 25 is further built into the plunger 81 of the fuel injection pump 26.

That is, the fuel injection pump 26 has a plunger 81 fitted on one side of the body 83 in parallel with the injection pipe 84 and movable up and down, and a pump chamber 82 partitioned by the body 84 and the plunger 81. The plunger 81 is formed into a hollow cylindrical shape with both ends closed, and its internal space constitutes the valve chamber 71 of the composite shutoff valve 25. A spool 72 is slidably inserted into this valve chamber 71.
As a result, the valve chamber 71 is divided into a pressure accumulation chamber 27 for pump return movement on the bottom dead center side of the movement stroke of the spool 72, and a biasing chamber 73 for shutoff valve return movement on the top dead center side.

This biasing chamber 73 for shutoff valve double operation is the pressure accumulator chamber 28 for double operation of the shutoff valve.
is communicated with. An internal inlet/outlet passage 74 communicating with the inlet/outlet passage 24 is opened at the intermediate height of the peripheral wall of the plunger 81, a pump communication passage 75 communicating with the pump chamber 82 is opened at the lower part thereof, and a shutoff valve is connected at the upper part thereof. Dynamic pressure storage chamber 28
and i! in the biasing chamber 73 for shutoff valve return operation. ! A tread pressure communication path 76 is opened. A hollow hole 77 is formed in the spool 72 and extends upward from the lower end surface of the spool 72.
The peripheral wall has a communication hole 78 extending from the middle height to the peripheral surface and always communicating with the internal inlet/outlet passage 74, and a communication hole 78 extending from the lower part to the peripheral surface when the spool 72 is located below the top dead center. a pump valve hole 79 that communicates with the pump communication passage 75; and a pressure accumulation valve that extends from its upper end to the circumferential surface and communicates with the pressure accumulation communication passage 76 when the spool 72 is located at the top dead center and the bottom dead center. A hole 80 is formed.

The pressure accumulation type fuel injector 29 includes an injection pipe 8'4 fitted in the other side of the body 83, and a fuel chamber 85 for valve closing pressurization and a first pressure accumulation chamber 96 in the lower half of the injection pipe 84. are formed in a series from top to bottom, and one or more (here, two) injection holes 87 are formed at the lower end of the injection pipe 84. The injection valve 8 that cuts off the connection between the first pressure accumulation chamber 96 and the injection hole 87 near the injection hole 87 is composed of a needle valve, and the upper end of the valve shaft 89 is formed in the upper half of the injection pipe 84. Closed valve spring chamber 9
Let it rush to 0. A valve-closing spring 91 that biases the injection valve 88 to close is housed in the valve-closing spring chamber 90.
An adjustment nut 92 for adjusting the biasing force of the injection pipe 84 is covered by a cover nut 93 screwed onto the upper end of the injection pipe 84 in an oil-tight manner. The internal space 94 of the cover nut 93 communicates with the valve-closing spring chamber 91, and together with this, the pressure accumulation chamber 28 for double operation of the shutoff valve.
It consists of Valve closing pressurization fuel chamber 85 and first pressure accumulation chamber 9
6 and is separated by a check valve 95. This check valve 95 includes a valve seat 100 formed by enlarging the diameter of a portion of the valve shaft 89, an annular valve body 101 that comes into contact with and separates from the plate surface of the valve seat 100, and a valve closing spring 102 that biases the valve to close the valve seat 100. Consisting of Further, a second pressure accumulation chamber 97 having an annular shape and partitioned by the intermediate height portion of the injection pipe 84 and the body 83 is provided, and this second M pressure chamber 97 is located on the opposite side from the fuel injection pump 26. It is connected to the first pressure accumulation chamber 96 by a second pressure accumulation chamber check valve 98 and a second pressure accumulation chamber pressure setting valve 99 arranged inside the body 83.
Together with the pressure accumulation chamber, an injected fuel pressure accumulation chamber 86 is configured. Note that the first pressure accumulation chamber 96 is formed to have a relatively small volume, and the second pressure accumulation chamber 97 is formed to have a relatively large volume.

In addition, the above discharge ill! ! all can be shut off by an emergency stop solenoid valve 13 immediately in front of the metering device 12, and the outlet passage 49 can be shut off by a manual stop valve 15.

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

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. In addition, the internal pressures of the shutoff valve double-acting pressure accumulating chamber 28, the pump double-acting pressure accumulating chamber 27, the shutoff valve double-acting biasing chamber 73, and the pump chamber 82 are controlled by pressure regulating bags! The reference pressure is regulated by 12. Here, time a in FIGS. 13(1) to 13(6) [hereinafter simply referred to as time a]. The same applies to the other points in FIG. 13(1) to FIG. 13(6)] to point b, the supply timing determining groove 58a of the supply timing determining valve 18 and the inlet/outlet passage 24 are communicated, and the yI amount/adjustment is performed. The pressurized fuel Vin is press-fitted into the unit injector 4.

This fuel Vin is first pressurized into the pump double-acting pressure storage chamber 27 as shown in FIG. 12(2), and the spool 72 is pushed up from the bottom dead center to an intermediate height. When the plunger 81 is lowered by the drive device 5 from the subsequent point C, the internal pressures of the pump chamber 82, the pump double-action pressure storage chamber 27, the shutoff valve double-action biasing chamber 73, and the cutoff valve double-action pressure storage chamber 28 gradually increase. As shown in FIG. 12 (3), the pump chamber 8
2, when an amount of fuel equal to the maximum injection lVmax is pressurized into the pump reciprocating pressure storage chamber 27, that is, the amount of fuel pushed out from the pump chamber 82 by the remaining stroke of the plunger 81 becomes equal to the pressurized fuel Vin. When this occurs, the spool 72 is raised to the top dead center. During the downward stroke of the plunger 81 from time C to time d when the spool 72 reaches the top dead center, the check valve 95 of the fuel injector 29 is closed and no fuel is pressurized into the fuel injector 29. This is called an invalid stroke. When the spool 72 reaches the top dead center, the internal pressure of the pump chamber 82 reaches the opening pressure of the check valve 95, and the pump communication passage 75 and the pump valve hole 7
9 is cut off. Further, the pressure accumulation valve hole 80 is connected to the pressure accumulation communication passage 7.
6, and the internal pressure of the pressure accumulation chamber 27 for double action of the pump is corrected so as to be equal to the internal pressure of the pressure storage chamber 28 for double action of the shutoff valve and the biasing chamber 73 for double action of the cutoff valve. And after this point d,
As the plunger 81 descends and the internal pressure of the pump chamber 82 further increases, fuel Vin is pressurized into the injection fuel pressure accumulation chamber 86. The fuel pressurized into the injected fuel pressure accumulator 86 is exclusively pressurized into the first pressure accumulator 98 until the time e when its pressure reaches the internal pressure of the second M pressure chamber 97, and the fuel is pressurized into the second pressure accumulator 97.
When the internal pressure exceeds the internal pressure, the second M pressure chamber check valve 98 is opened and the second M pressure chamber 97 is also pressurized. When the internal pressure of the second pressure accumulation chamber 97 exceeds the set pressure of the pressure accumulation setting valve 99, the pressure accumulation setting valve 99
is opened, and check valve 98 is closed. Figure 12 (4)
As shown in FIG. 1, at one point in time when the plunger 81 reaches the bottom dead center, the fuel pressure stops rising, the check valve 95 is closed, and the fuel Vin is accumulated at high pressure in the injection fuel pressure accumulation chamber 86. Then, at a predetermined point g thereafter, the inlet/outlet passage 24 is connected to the pressure relief valve body passage 59, the advance valve body passage 62, and the breathing passage 7.
0 to the depressurized fuel breathing chamber 21, and the inlet/outlet passage 2
The internal pressure of No. 4 begins to decrease. The timing for starting this pressure reduction is set by the pressure relief valve passage 59 communicating with the advance valve body passage 62 communicating with the inlet/outlet passage 24, so if the engine rotational speed is high, (It will be faster than the mental timing, and if the engine speed is slow, it will be slower than the standard timing.)

- That is, as the engine rotation speed increases, the internal pressure of the advance pressure receiving chamber 63 increases in direct proportion to the engine rotation speed.
The advance valve body 61 is moved in the advance direction, and the pressure relief valve body passage 59 on the rotationally upper side of the main shaft 7 and the advance valve body passage 62 communicate with each other, so that the pressure relief valve body in the center The entrance/exit passage 24 is opened earlier than when the passage 59 and the advance valve body passage 62 communicate with each other.
is communicated with the advance valve body passage 62 via the pressure relief valve body passage 59, so that the injection timing can be advanced.

Furthermore, when the engine speed becomes low, the pressure relief valve passage 59 and the advance angle valve passage 62 on the rotationally downstream side of the main shaft 7 are
By communicating with each other, the entrance/exit passage 2 is opened later than when the center pressure relief valve body passage 59 and the advance valve body passage 62 communicate with each other.
4 is communicated with the advance valve body passage 62 via the pressure relief valve body passage 59, so that the injection timing is delayed. At intermediate speeds, the central pressure relief valve passage 59 and the advance angle valve passage 6
2 connects, I5! The inlet/outlet passage 24 is communicated with the advance valve element passage 62 via the pressure relief valve element passage 59 at a standard timing, and pressure relief for injection is performed at a standard timing. The advance valve body passage 62 not only selectively communicates with each pressure relief valve body passage 59 (but also communicates with the center and the most advanced pressure relief valve body in the transient region of the corresponding rotational speed region). 2 of the passage 59 or the center and lowest pressure relief valve body 1jIl passage 59
It can communicate with the main pressure relief valve body passage 59 at the same time, and the rising characteristics of pressure relief change depending on the proportion of the connection area with the side pressure relief valve body passage 59. In this way,
Since the position of the advance valve body 61 can be controlled easily and highly accurately depending on the pressure regulation characteristics of the pressure regulator 12 with respect to the engine rotational speed, the advance timing can be easily and precisely controlled.

From the time h when the spool 72 gradually descends from the top dead center and the communication between the pump valve hole 79 and the pump communication passage 75 is restored, the internal pressure of the fuel chamber 85 for valve closing pressurization decreases rapidly, and the predetermined valve opening pressure is reached. From time point i, when the internal pressure of the fuel chamber 85 for valve closing pressurization has dropped to the point i, the differential pressure acting on the check valve 95 overcomes the biasing force of the valve closing spring 91, and the injection valve 88 is opened.

As mentioned above, when the spool 72 reaches the top dead center,
Since the pressure accumulation valve hole 80 and the pressure accumulation communication passage 76 are communicated with each other, the internal pressure of the pump double-action pressure storage chamber 27 is increased due to leakage of fuel from the pump chamber 82 to the pump double-stroke pressure storage chamber 27 when fuel is pressurized into the injector 29. is corrected, and the timing at which the pump communication passage 75 and the pump valve hole 79 communicate with each other during pressure relief is prevented from being delayed. This prevents an error (delay) in injection timing from occurring due to this communication delay.

Here, the pump communication passage 75 is composed of a small diameter pump communication passage 75a and a large diameter pump communication passage 75b arranged vertically, and when the spool 72 starts to descend from the bottom dead center, the small diameter pump communication passage 75a first connects to the pump valve hole 79. 1ffiL, the decrease in the internal pressure of the pressure accumulation chamber 86 for closing the valve is suppressed relatively slowly, the valve opening mechanism of the injection valve 88 is limited to a small amount, and the fuel injection ■ is suppressed to a small amount, and the injected fuel pressure is accumulated by fuel injection. The reduction in the internal pressure of the chamber 86 is suppressed to a small level. Then, when the spool 72 further descends and reaches, for example, time j corresponding to the ignition time at the rated rotational speed, the large diameter pump communication passage 75
b communicates with the pump valve hole 79, the internal pressure of the pressurizing fuel chamber 85 is reduced to 2a, and the injection valve 88 is suddenly widened (opened, and a large amount of fuel is vigorously injected at high pressure). In this way, by suppressing the amount of fuel injected before ignition to a small amount, it is possible to reduce the explosion noise at the time of ignition and prevent operational noise.In addition, a large amount of fuel is injected at high pressure after ignition. By doing so, it is possible to obtain the maximum thermal efficiency that is allowed in order to reduce operational noise.Also, since the injection pressure is injection twist f: + the internal pressure of the pressure accumulation chamber 86 is high pressure,
A predetermined amount of fuel Vin can be completely injected in a short time. After the internal pressure of the injected fuel accumulator 86 becomes equal to or lower than the set pressure of the second pressure accumulator setting valve 99, this pressure accumulator setting valve 99 is closed, and the internal pressure of the second M pressure chamber 97 is reduced to the set pressure. held above pressure. On the other hand, the volume of the injected fuel pressure accumulation chamber 86 communicating with the injection hole 87 is substantially equal to that of the first M pressure chamber 96.
Even if a small amount of fuel is injected, the internal pressure of the first pressure accumulating chamber 96 is greatly reduced, and in a short time, this internal pressure is reduced to a predetermined valve closing pressure, and the injection valve 88 is closed. (1 point in time). Therefore, the injection time can be significantly shortened, which is advantageous in increasing the speed of the engine. At a predetermined time m after the fuel injection ends, the cam lift of the fuel injection cam 30 of the drive device 5 begins to decrease, and the pump chamber 8
2, the plunger 81 is pressed against the rocker arm 33 of the drive device 5 and rises.

As the plunger 81 rises, the volume of the pump chamber 82 is expanded, and the internal pressure of the pump chamber 82 and the pressure accumulation chamber 27 for double action of the pump is reduced, so the spool 72 is lowered by the pressure of the biasing chamber 73 for double action of the shutoff valve. until an amount of fuel equal to the maximum injection IJ Vmax is pressurized from the pump reciprocating pressure accumulator 27 to the pump chamber 82.
Fuel is forced into the pump chamber 82 from there.

By the way, during the pressure relief period after time g, fuel is released from the pump double-acting pressure accumulation chamber 27 to the pressure relief fuel breathing chamber 21 side, so if the spool 72 is lowered to the bottom dead center, the timing control port The amount of fuel injected from the composite valve device 3 into the unit injector 4 side becomes smaller than the initial state, and when the pressure-regulated fuel is then pressurized into the unit injector 4, the spool 72 moves to the unit injector 4 side.
The engine only rises to a position lower than the height that it should rise to in response to this, resulting in operational noise and errors in injection timing control, as well as inconveniences such as an insufficient amount of fuel to be injected next time.

Therefore, at time point n when the spool 72 descends to the vicinity of the bottom dead center, the depressurized fuel breathing chamber 21 is communicated with the inlet/outlet passage 24 via the breathing passage 70 and the depressurized fuel return passage 22, and the discharge urging means 69 As a result, the fuel that had been forced into the depressurizing fuel breathing chamber 21 for depressurization is discharged back into the inlet/outlet passage 24, and is further discharged into the pump reciprocating pressure accumulating chamber 27 and the pump chamber 82. By spitting out the fuel sucked out in this way back to the unit injector 4, occurrence of fuel shortage during the next injection is prevented. However, since the pressure of the fuel contained in the depressurized fuel breathing chamber 21 is higher than the initial pressure,
The internal pressure becomes higher than the initial state, and the spool 72 is moved slightly from the vicinity of the bottom dead center toward the top dead center. Therefore, in order to return from this state to the initial state, finally at a predetermined time point 0, the initial pressure supply path 23 is communicated with the inlet/outlet passage 24, and the shutoff valve double-acting pressure accumulator 28, the pump double-acting pressure accumulator 27, and the shutoff valve The internal pressure of the double-acting biasing chamber 73 and the pump chamber 82 is returned to the standard pressure regulated by the pressure regulating bag Wl 2,
The spool 72 is returned to the bottom dead center.

By the way, the internal pressures of the shutoff valve double-acting pressure accumulator 28 and the shutoff valve double-actuate biasing chamber 73 are increased due to fuel leak from the second pressure accumulator 97, or due to leakage to the pump double-acting pressure accumulator 27 when the pressure is released. It is possible that the pressure is reduced. If the internal pressure of the shutoff valve double-acting pressure accumulation chamber 28 and the shutoff valve double-acting energizing chamber 73 increases, next time! When the JiI quantity supply bag supply device 2 material is press-fitted, the internal pressure of the pressure accumulation chamber 2B for shutoff valve double action prevents the spool 72 from rising, and the pressure accumulation volume of the pressure accumulation chamber 27 for pump double action is narrowed. As a result, after fuel is pressurized into the injector 29, when the plunger 81 rises, the amount of fuel pressurized into the pump chamber 82 from the pump reciprocating pressure accumulation chamber 27 is insufficient, and the plunger 81 cannot rise to the top dead center (
As a result, driving noise will be generated. Moreover, if the internal pressure of the shutoff valve double-acting pressure accumulation chamber 28 and the shutoff valve double-acting biasing chamber 73 is reduced, fuel will be pressurized from the metering supply device 2 next time.
When the plunger 81 is lowered, the timing at which the pump communication passage 75 and the pump valve hole 79 are shut off is delayed, resulting in a decrease in the amount of fuel injection.

Here, when the spool 72 is returned to the bottom dead center, the pressure accumulation valve hole 80 communicates with the pressure accumulation communication passage 76 again, and the internal pressures of the pressure accumulation chamber 28 for shutoff valve return operation and the biasing chamber 73 for cutoff valve return operation are set to the reference pressure (
Since the internal pressure is corrected to the initial pressure, it is possible to prevent the occurrence of operational noise due to an increase in these internal pressures and the occurrence of an error (reduction) in the injection amount due to a decrease in pressure.

Here, the injected fuel breathing chamber 21 is provided to prevent the depressurized fuel from being discharged to the outside, but the provision of the injected fuel breathing chamber 21 is not essential to the present invention, and it is possible to omit it. Pressure regulating device 12 simply via advance pressure receiving chamber 63
The initial pressure supply path 23 communicated with the inlet/outlet passage 2 of the valve box 56
4, the pressure regulator 12 is connected to the advance pressure receiving chamber 63, the initial pressure supply passage 23, the inlet/outlet passage 24, and the cutoff valve 25 to the pump reciprocating pressure accumulation chamber 27 and the pump chamber 82. It is also possible to replenish fuel to the valve-closing pressure accumulating chamber 85 and return it to its initial state.

<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 advance device includes a valve body of a pressure relief valve for determining injection timing, which has a pressure relief passage for determining injection timing; An advance valve body having an advance valve body passage, a retard biasing means for biasing the advance valve disc in a retard direction, and an advance valve disc for biasing the advance valve disc in an advance direction. Since the angle pressure receiving chamber and the angle pressure receiving chamber are configured as one valve, the configuration of the angle advance device can be simplified. Further, since the fuel injection device has a built-in mechanism for determining the injection timing and an advance device for adjusting the injection timing, it can be used for general purposes regardless of engine size or the like.

Furthermore, since the operating principle and structure of the advance angle device are simple,
High reliability with no failures. In addition, fuel equivalent to the amount of fuel that is lost due to pressure relief during injection is replenished from the pressure regulator via the initial pressure supply path, and the fuel injector, fuel injection pump, and pump return pressure accumulator are reliably returned to their initial states. This ensures that the plunger rises to the top dead center, prevents gaps from forming between the parts of the drive device for driving the fuel injection pump, or between the drive device and the plunger, and prevents the parts of the drive device from being connected to each other or between them. It is possible to prevent operation noise caused by the impact between the drive device and the plunger, and errors in injection timing control caused by vibrations of parts of the drive device, and also to prevent insufficient injection amount during the next fuel injection. In addition, the mechanism for returning the fuel injector, the fuel injection pump, and the pump reciprocating pressure accumulation chamber to the initial state is simply a timing control system that communicates with the advance valve body from the advance pressure receiving chamber to the pressure release valve body passage. It is only necessary to form an initial pressure supply path, making it simple.

[Brief explanation of the drawing]

FIG. 1 is an equivalent circuit diagram showing the overall configuration of a pressure accumulation type fuel injection device for a diesel engine according to an embodiment of the present invention, and FIG.
Figure 3 is a longitudinal sectional side view of the fuel metering supply device and timing control compound valve device, Figure 3 is a vertical sectional front view of the transfer pump, Figure 4 is a vertical sectional front view of the pressure regulating device, and Figure 5 is the pressure pump. FIG. 6 is a longitudinal sectional front view of the pump, FIG. 6 is a longitudinal sectional side view of its timing control compound valve device, and FIG. 7 is an exploded view showing the arrangement of each valve body passage, depressurization fuel return passage, and initial pressure supply passage according to the timing chart. Figure 11 is a longitudinal sectional view of the unit injector, Figure 12 (1) to Figure 12 (4)
13(1) to 13(6) show the operation timing of each part of the unit injector, pressure changes, and timing control complex valve device. Timing diagrams showing the relationship between operation timings and FIG. 14 are configuration diagrams of a conventional fuel injection device and an advance angle device. 1... Fuel tank, 12... Pressure regulator, 14...
Metering device (metering supply device), 19... Pressure relief valve for determining injection timing, 20... Advance angle valve for adjusting M during injection, 21...
Pressure release fuel breathing chamber, 23... Initial pressure supply path, 24...
Inlet/outlet passage (inlet), 25...Compound shutoff valve (shutoff valve)
, 26...Fuel injection pump, 27...Pressure accumulation chamber for pump double action, 29...Pressure accumulation type fuel injector, 5G...Valve box, 57...Valve body for construction method, 59...Pressure Extraction valve body passage,
61... Valve element for advance angle, 62... Valve element passage for advance angle (passage for advance angle), 63... Pressure receiving chamber for advance angle, 65... Retard angle biasing means, 85...・Pressure accumulation chamber for pressurizing valve closing, C...Crankshaft. Patent applicant: Kubota Iron Works Co., Ltd.
' Figure 3 Figure 4 Figure 5 Figure 6 Figure 10 Figure 12 (1) Gong Figure 12 (2) □-1) Arrow Figure 14

Claims (1)

[Claims] 1. The fuel tank 1 of a diesel engine is connected to a pressure regulator 12.
, through the metering device 14, the cutoff valve 25, and the fuel injection pump 26, are connected to the pressure accumulation type fuel injector 29, and the fuel injection pump 26 is communicated with the pressure accumulation chamber 27 for pump return action via the cutoff valve, and the pressure is adjusted. The device 12 is a pressure accumulation type fuel injection device for a diesel engine configured to increase the fuel supply pressure in accordance with the rotational speed of the engine. Pressure relief valve 1 for determining injection timing via 25
9 and the injection timing adjustment advance valve 20 are connected in this order, and the pressure relief valve 19 is connected to the pressure relief valve body 5 to the inlet 24 of the valve box 56.
The advance valve 20 is configured to connect the pressure relief valve body passage 59 of No. 7 to the crankshaft C in timing communication, and the advance valve 20 connects the pressure relief valve body passage 59 along the rotational direction of the pressure relief valve body 57. A plurality of advance valve bodies 61 are provided, and the advance passages 62 of the advance valve bodies 61 are selectively communicated with the advance valve bodies 61 through the advance valve body passages 59 . The pressure receiving chamber 63 is configured to be biased toward the retard side and biased toward the advance side by the fuel pressure in the advance pressure receiving chamber 63.
an initial pressure supply path 23 independent from the pressure relief valve body passage 58 is formed in the pressure relief valve body 57, and a starting end of the initial pressure supply path 23 is communicated with the advance pressure receiving chamber 63; , a pressure accumulation type fuel injection device for a diesel engine, characterized in that the terminal end thereof is configured to be able to communicate with the introduction port 24 of the pressure relief valve 19 for determining injection timing.