JPS6029830B2 - Internal combustion engine fuel injection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention controls a servo piston having a larger diameter than a plunger by a solenoid valve, and injects high-pressure fuel generated by the plunger interlocking with the servo piston from an injection nozzle. This invention relates to an injection device for an internal combustion engine.

As a conventional fuel injection device of this type, the
5254 and Japanese Patent Publication No. 54-26651 are known, but each of these conventional fuel injection devices has the following drawbacks.

That is, the fuel injection device of Japanese Patent Publication No. 54-35254 shown in FIG. Outlet 204 of spherical movable valve 203 interlocked with
The hydraulic pressure acting on the end face 206 of the slide valve 202 is adjusted and operated by opening and closing the inlet 205. Therefore, when increasing the area of the inlet and outlet of the movable valve 203, the moving parts 201 and 202 are Since the mass increases, a more powerful solenoid 211 is required to make the moving part more powerful, and the pressure receiving area of the movable valve 203 increases, so the solenoid valve 201 must be a pressure balance type, and the fuel injection The structure of the device itself becomes complicated, the durability is 0, and the movable valve is 20.
There were problems with durability, such as the worn surface of No. 3 rotating, resulting in poor oil tightness, and the valve seat diameter changing due to wear, resulting in loss of pressure balance.

[2] Since the inlet 211 and outlet 212 of the servo piston chamber 207 are used as one control hole 208,
There is a problem in that the conical protrusion 210 formed on the servo piston 209 to control the injection pattern during the injection stroke also has an effect during the filling stroke. In the fuel injection device of Japanese Patent Publication No. 54-26651 shown in FIG. 13, when the solenoid valve 305 moves downward, the solenoid valve
5 closes the inlet port 303 of the piston chamber 304, at which time the valve 306 directly connects the outlet port 302 of the servo piston chamber 304, while the upward movement of the solenoid valve 305 Sometimes, conversely, the valve 301 opens the inlet 303 and the valve 3
06 closes the outflow port 302, so the inflow port 30 of the servo piston chamber 304 is closed by the pressure load of the solenoid valve 305 and the suction force of the solenoid 307.
3 and the size of the outlet 302, it is difficult to inject a large amount of fuel at high pressure by shortening the fuel injection time.

In view of the problems of the conventional fuel injection device as described above, the present invention opens and closes the inlet of the servo piston chamber with a conical valve controlled by a solenoid valve.
It is possible to optimally control the amount and timing of fuel injection and the rotational speed of the engine over the entire range of use of the engine, and
The object of the present invention is to provide a fuel injection device for an internal combustion engine that is simple in structure, small in size, and light in weight, which facilitates high-pressure injection of fuel.

Hereinafter, the fuel injection device for an internal combustion engine of the present invention will be explained by referring to the embodiment shown in FIGS. 1 to 11. FIG. A fuel injector Z is shown.

This fuel injection device Z has a nozzle at its tip inserted into a pump nozzle mounting hole 6 provided in a cylinder head 2 with a cylinder tab. a pump nozzle x attached by a nozzle holder 13 so as to face into the working chamber 4 formed above the piston 5 in the housing 1; a fuel supply pump 18 disposed outside the diesel engine Y; It is composed of a controller 20 that controls a solenoid valve (described in detail later) housed in the pump nozzle, and the fuel is sent into the pump nozzle via the fuel pipe 10 and the fuel supply pipe 11 by the fuel supply pump 18. A predetermined amount of fuel is injected into the working chamber 4 by controlling the solenoid valve of the pump nozzle It looks like this. The structure of this pump nozzle X will be explained in detail below.

Pump nozzle × is the nozzle valve 3 as shown in Figure 2.
2, a pump section 55 having a plunger 59 and a servo piston 60 for driving the plunger 59, and a servo piston 60 of the pump section 55.
A control unit 10 having a solenoid valve 111 that controls
5 are sequentially connected coaxially. As shown in FIGS. 2, 4, and 7, the injection nozzle section 30 includes a nozzle body 31 into which a nozzle valve 32 is slidably inserted, a short-melting nozzle stop baser 33, and an injector. The nozzle valve 32 is normally closed by a spring 36 in a nozzle spring seat insertion hole 40 which is formed by extending over the nozzle stop baser 33 and the injector cage 34. A nozzle spring seat 39 that biases in the direction is iron-mounted.

The nozzle body 31, nozzle stop baser 33, and injector cage 34 are integrally and longitudinally attached to the tip of a plunger body 58, which will be described later, by means of a nozzle mounting nut 35. In addition, nozzle stop baser 33
The end face 33a on the nozzle body 31 side is the nozzle valve 3.
By colliding with the upper end surface 32a of the nozzle valve 2, the upper limit of the lift of the nozzle valve 32 is restricted. The upper end surface of the injector cage 34 is provided with a plunger body 5, which will be described later.
A groove 41 extending in the radial direction is formed to allow the plunger chamber 67 and feed valve chamber 68 of No. 8 to communicate with each other. Furthermore, this groove 41 is connected to the vertical hole 42 of the injector cage 34 and the diagonal hole 4 of the nozzle stop baser 33.
3 and an annular groove 44 of the nozzle body 31 and an oblique hole 45 to allow the oil to pass through the oil reservoir chamber 38 formed at the tip of the nozzle body. An oil passage 46 extending from the groove 41 to the oil reservoir chamber 38 is for sending pressurized high-pressure fuel into the oil reservoir chamber 38, and hereinafter, this oil passage 46 will be referred to as high-pressure fuel 46. In addition, on the upper end surface of the injector cage 34, a diagonal hole 47 is formed outside the concave groove CI, as shown in FIG. has been done. In addition, the reference numeral 37 is a shim for adjusting the spring 36, 48, 48
4 shows a parallel pin for positioning the plunger body 58, the injector cage 34, and the nozzle stop baser 33 in the circumferential direction, and 49 indicates a hole, respectively. Pump part 5
5 is a servo having a plunger body 58 having a plunger chamber 67 for accommodating a plunger 59 and a servo piston chamber 76 for accommodating a servo piston 60, as shown in FIGS. 2 to 5 and 7. A piston body 57 and a conical valve body 56 having a conical valve chamber 84 for accommodating a conical valve 61 to be described later are fastened together with bolts 85, 85 (Fig. 5).
It is constructed by fastening and fixing it coaxially. A servo piston chamber 76 formed by penetrating the servo piston body 57 in all directions of its axis extends coaxially with a plunger chamber 67 formed by penetrating the plunger body 58 in its axial direction. A large-diameter servo piston 60 is inserted into the servo piston chamber 76, and a small-diameter plunger 59 is inserted into the plunger chamber 67 so as to be slidable in the axial direction.
The servo piston chamber 76 and the plunger chamber 67 are caused to integrally reciprocate in accordance with the pressure of fuel flowing into and out of the chamber 76 and plunger chamber 67. The fuel injection pressure is determined by the cross-sectional area ratio of the servo piston 60 and the plunger 59. Further, the servo piston chamber 76 and the plunger chamber 67 are formed eccentrically by an appropriate dimension with respect to the centers of the servo piston body 57 and the plunger 58, respectively. The conical valve body 56 has a horizontal hole 71 of an appropriate depth formed in the radial direction from one side thereof, and the fuel supply pipe 11 is formed at the outer end of the horizontal hole 71.
1 is screwed on.

This horizontal hole 71 is a passage for receiving fuel pumped from the fuel supply pump 18, and hereinafter, this horizontal hole 7
1 is referred to as a supply fuel passage 71. A conical valve chamber 84 and a servo piston chamber inlet 77 are coaxially formed in the center of the conical valve body 56 so as to extend perpendicularly to the fuel supply passage 71. This servo piston chamber inlet 77 is connected to the servo piston 6 inserted into the servo piston chamber 76 from the servo piston chamber inlet 77.
A conical valve 61 whose opening end face on the side of the supply fuel passage 71 will be described later
The valve seat 79 is for On the other hand, the conical valve chamber 84 is provided from the upper end surface of the conical valve body 56 toward the supply fuel passage 71, and within the conical valve chamber 84, the conical valve 61 can be freely moved in all directions. It is fitted with iron. The conical valve 61 is formed into a bottomed cylindrical shape with the supply fuel passage 71 side closed, and is moved up and down by controlling the back pressure in the conical valve chamber 84, and its tip is connected to the servo piston chamber 84. The servo piston acts to open and close the inlet 77 by being seated on or separated from the valve seat 79 of the inlet 77 .

This conical valve 61 has a small hole 156 formed in the side wall of its distal end so as to allow communication between the conical valve chamber 84 and the fuel supply passageway 1. This small hole 156 functions as a fuel introduction port for introducing fuel oil in the supply fuel passage 71 into the conical valve chamber 84, and hereinafter, this small hole 156 will be referred to as a fuel introduction row 56. This conical valve 61 is inserted into the conical valve chamber 84 with its fuel introduction row 56 facing in an arbitrary direction with respect to the supply fuel passage 71, and is also inserted into the conical valve chamber 84 with its fuel introduction row 56 facing in an arbitrary direction with respect to the supply fuel passage 71. It is always urged toward the conical valve seat 79 by the urging force. Further, one end of the conical valve chamber 84 is closed by the lower end surface of a short rattan-shaped solenoid valve seat 128 attached to the outer end surface thereof.

This solenoid valve seat 128 has a large diameter solenoid valve insertion hole 164 formed in the center of the outer surface thereof, and a small diameter solenoid valve insertion hole 164 and a conical valve chamber 84 formed on the conical valve chamber 84 side. The lotus is passed through the lotus through hole 155. This Rendong Roku15
5 serves as a fuel discharge port for discharging the fuel oil that has flowed into the conical valve chamber 84. Hereinafter, this lotus through hole 155 will be referred to as the fuel discharge row 55, and the solenoid valve insertion hole 164 will be referred to as the fuel discharge row 55. Valve seat 161
That's what it means. This fuel discharge row 55 has an inner diameter larger than the fuel introduction row 56 formed in the conical valve 61 by an appropriate size, and when the fuel discharge row 55 is in the open position, the fuel discharge row 55 passes through the fuel introduction row 56 and is conical. Valve chamber 84
The fuel oil flowing into the conical valve 61 is appropriately throttled to create a pressure difference before and after the conical valve 61. On the other hand, an annular groove 80 of an appropriate width is formed on the sliding surface of the conical valve 61 against the chamber wall of the conical valve chamber 84.

This annular groove 8 has a conical valve 6 as shown in FIG.
When the conical valve 61 is closed, it passes through the oil escape hole 88 formed by penetrating the conical valve chamber 84 in its closed direction, and when the conical valve 61 is opened, it is in a non-open state. The formation positions in all directions of the axis are set appropriately. One end of this oil escape hole 88 is passed through the servo piston chamber 76 via the servo piston chamber outlet 87,
The other end is connected to the external fuel tank 19 via an orifice 89 and a recess 90 formed on the lower end surface of the conical valve body 56. Hereinafter, the servo piston chamber outlet 87, the annular groove 80, the oil escape hole 88, and the concave groove 90.
A series of passages 94 consisting of this is called a hydraulic oil relief passage 94.
Further, the groove 90 corresponds to the vertical hole 92 of the servo piston body 57.
The oil is passed through the back pressure side of the servo piston 60 through the diagonal hole 93 of the plunger body 58, and leaked oil from the servo piston 60 is discharged to the fuel tank 19 side through the diagonal hole 93 and the vertical hole 92. Ru. Therefore, when the conical valve 61 is opened, the servo piston chamber outlet 87 is closed, so that the fuel introduced into the servo piston chamber 76 from the servo piston chamber inlet 77 moves the servo piston 61 due to its fuel pressure. When the conical valve 61 is closed, the servo piston chamber outlet 87 is opened, so that the servo piston 61 absorbs the fuel introduced into the plunger pump chamber 67 via the feed valve 62, which will be described later. is moved upward by the pressure of Furthermore, a feed valve chamber 68 is formed at the lower end of the plunger body 58 so as to close one end of the groove 41 of the injector cage 34 .

The feed valve chamber 68 is in communication with the plunger chamber 67 via the groove 41. The upper end of the feed valve chamber 68 is connected to the supply fuel passage 71 through an oblique hole 74 of the plunger body 58, a vertical hole 73 of the servo piston body 57, and a vertical hole 72 of the conical valve body 56.
It is said to be unlucky. A feed valve 62 having small holes 69, 69 is iron-mounted within the feed valve chamber 68, and the feed valve 62 is normally biased in the valve closing direction by the spring force of a spring 64. A series of oil passages 7 from this supply fuel passage 71 to the feed valve chamber 68 are for filling fuel into the plunger chamber 67. Hereinafter, this oil passage 70 will be referred to as a fuel filling passage. As shown in FIG. 7, the pump portion 55 is formed with an oil passage 86 that allows the fuel supply passage 71 to communicate directly with the nozzle spring seat iron insertion hole 40 of the injector cage 34.

The oil passage 86 (Fig. 7), which is composed of the diagonal hole 81 of the conical valve body 56, the vertical hole 82 of the servo piston body 57, the diagonal hole 83 of the plunger body 58, and the diagonal hole 47 of the injector cage 34, is connected to the nozzle. The opening pressure of the valve 32 is determined by the mounting load of the nozzle spring 36 and the nozzle valve 32.
This oil passage 86 serves as a passage for fuel sent into the nozzle spring seat insertion hole 40 in order to generate the back pressure determined by the sum of the back pressure load and the back pressure load. It is called a fuel passage 86. still,
Reference numeral 63 indicates a parallel pin for circumferential positioning between the conical valve body 56, the servo piston body 57, and the plunger body 58. As shown in FIGS. 2 and 3, the control section 105 includes a solenoid coil 116 whose excitation timing and excitation time are controlled by the controller 20', and a solenoid valve 11 whose opening/closing valve is driven by the attraction force of the solenoid coil 116. It is configured.

The solenoid valve 111 has four-way sliding portions 134 and 138 formed at both ends of a shield of an appropriate length (recessed grooves may be formed at both ends of the shield in all directions), and
A needle-like valve body 136 of an appropriate length is protruded from the end face of one of the four-way sliding portions 138.

This solenoid valve 111 has a short cylindrical active core 131 having a small-diameter communication hole 158 and a large-diameter solenoid valve fixing hole 163 in the axial center, which is integrally formed by press-fitting into the four-way valve part 134 on the opposite side of the valve body. While fixing, the four-way sliding portion 138 on the valve body side is inserted into the solenoid valve iron insertion hole 164 of the solenoid valve seat 128.
The valve body 136 can be seated or separated from the valve seat 161. At this time, the solenoid valve fixing hole 163 of the active core 131 and the four-way sliding portion 13 of the solenoid valve 111
As shown in FIG. 9, four lotus passages 160, 160, 160, . Between the solenoid iron insertion hole 164 and the four-sided sliding surface of the other four-sided marsh part 138 of the solenoid valve 111, there are four lotus passages 159, 159 penetrating in the vehicle direction as shown in FIG.
... is formed. Each of these transportation routes 159, 159
・・・・・・・・・,160,160・・・・・・・・・
- indicates the concave portion 157 and the static core 13 described later.
3 and an internal space 150 of the upper support 118, which will be described later, form a conical valve chamber outflow passage 165 through which the fuel discharge row 55 of the conical valve chamber 84 and the fuel return pipe 124 (FIG. 2) pass through. There is. A core guide 130 for accommodating an active core 131 is loosely fixed to the upper part of the solenoid valve seat 128 by a lower support 115.

This core guide 130 is formed into an elongated cylindrical shape with a flange, and has a large diameter core port insertion hole 162 that opens on the lower surface of the core guide 130 at the lower part of the shaft 0 part, and the core group insertion hole at the upper part. The core guide 130 has a threaded hole 164 having a diameter of 4 mm, which is continuous with the core guide 162 and opens on the upper surface of the core guide 130. A static core 133 formed in the shape of a stepped, elongated cylinder is slidably inserted into the upper part of the core iron insertion hole 162 . This static core 133 has its small light part connected to the core guide 1.
30, and a lock nut 121 is screwed onto the end protruding from the upper surface of the core guide. On the other hand, the active core 131 is slidably inserted into the lower part of the core insertion hole 162. A spring 132 is interposed between the active core 131 and the static core 133, and the solenoid valve 111 is always urged toward the valve seat 161 side of the solenoid valve seat 128 integrally with the active core 131, thereby forming a conical valve. Fuel discharge row 55 of chamber 84
is closed. The valve lift of the solenoid valve 111 is determined by the gap h between the upper surface of the active core 131 and the lower surface of the static core 133. It can be adjusted as appropriate by changing the relative position of. A solenoid valve 11 is located in a space 115a formed between the lower support 115 and the core guide 130.
A cylindrical solenoid coil 116 for opening and closing 1 by its suction force is equipped with iron.

This solenoid coil 116 is connected to the solenoid coil 1.
The center of the active core 131 in the axial direction is located above the center of the active core 131 in the axial direction so that the active core 131 can be attracted and moved upward when the active core 16 is excited. Therefore, when the solenoid coil 116 is energized, the solenoid valve 111 is pulled upward together with the active core 131 by its attractive force, and acts to open and close the outflow row 55 of the conical valve chamber 84. still,
Reference numeral 117 indicates a yoke, 120' a coupling nut for integrally coupling the core guide 130 and the lower support 115, 122 a pipe joint bolt, and 126 a connection terminal of the solenoid coil 116, respectively. Next, the operation and effect of the fuel injection device for an internal combustion engine according to the illustrated embodiment will be explained with reference to FIGS. 10 and 11 (simplified diagrams of the fuel injection device). , the fuel supply pump 18 driven by the internal combustion engine Y supplies the fuel in the fuel tank 19 to the pump nozzle Accordingly, the controller 20 controls the opening and closing of the solenoid valve 11 in the pump nozzle X as appropriate.

Note that the supply pressure of the supplied fuel is appropriately set by the pressure regulating valve 24, and the pressure pulsations thereof are absorbed by the accumulator 25. First, referring to FIG. 10, the operation of the pump nozzle x when the solenoid coil 116 is energized will be explained.
is excited when energized by the controller, and its attraction force causes the solenoid valve 11 to move upward, thereby controlling the fuel discharge row 55 of the conical valve chamber 84.

When the fuel discharge row 55 is opened, the conical valve chamber 8
At the same time, the fuel oil stored in the conical valve chamber 4 flows out to the fuel tank 19 side through the conical valve chamber fuel discharge passage 165, and at the same time, the fuel oil in the supply fuel passage 71 flows out through the fuel inlet 156.
It flows into the conical valve chamber 84 through the conical valve chamber 84 . At this time,
Since the passage area of the fuel introduction row 56 is made smaller than the passage area of the outlet 155, the conical valve 61 has a size that causes a throttle outflow effect of the fuel that creates a pressure difference before and after the conical valve 61. Due to the generation of a pressure difference between the fuel pressure in the supply fuel passage 71 and the fuel pressure in the conical valve chamber 84, the conical valve chamber 84
The servo piston chamber inlet 77 is moved upward toward the side.
to speak out loud. When the servo piston chamber inlet 77 is opened, the fuel oil in the supply fuel passage 71 flows into the servo piston chamber 76.
be introduced within. At this time, the servo piston chamber outlet 87
Since the servo piston 6 is closed by the fluid surface of the conical valve 61, the servo piston 6 is pushed downward by the fuel oil. When the servo piston 60 is pushed down, the plunger 59 is also pushed down together with the servo piston 60. When the plunger 59 is moved downward, the fuel oil in the plunger chamber 67 is pressurized, the feed valve 62 is closed by the fuel pressure, and the fuel pressure in the nozzle oil reservoir chamber 38 is suddenly increased. The nozzle valve 32 is connected, and the fuel in the plunger chamber 67 sequentially passes through the high pressure fuel passage 46 to the counterfeit ports 49, 49.
It is injected into the working chamber 4 from... When the plunger 59 descends to the lower lift limit position, the nozzle oil reservoir chamber 3
8, the pressure of the fuel oil flowing into the nozzle spring seat insertion hole 40 via the urging force of the spring 36 acting on the nozzle valve 32 and the nozzle valve urging fuel passage 86 causes the nozzle valve to close. 32 is closed and fuel injection ends. Next, referring to FIG. 11, the operation of the pump nozzle x when the solenoid coil 116 is de-energized from the energized state will be described. When the solenoid coil 116 is de-energized, the suction force on the solenoid valve 111 is released. The solenoid valve 111 is moved downward by the spring force and closes the fuel outlet 155 of the conical valve chamber 84.

When the fuel discharge row 55 is closed, the conical valve 61
The fuel pressure before and after the conical valve 61 is balanced.
is moved downward by the spring force of the spring 65 to close the servo piston chamber inlet 77. When the conical valve 61 moves downward, the annular groove 80 formed on its sliding surface fits in with the oil escape port 88, so the servo piston chamber outlet 88
7 is closed, the fuel oil in the servo piston chamber 76 flows out to the fuel tank 19 side through the fuel relief passage 94, and the oil pressure in the servo piston chamber 76 drops. Then, the hydraulic pressure in the plunger chamber 67 also decreases. For this purpose, the high-pressure fuel oil in the fuel filling passage 70 pushes open the feed valve 62 and flows into the plunger chamber 67, further moving the plunger 59 and the servo piston 60 upward, thereby filling the plunger chamber 67. By sequentially repeating the injection process shown in FIG. 10 and the filling process shown in FIG. 11, the internal combustion engine Y is continuously operated.

Further, the injection amount of the pump nozzle X is determined by the fuel filling time, that is, the return stroke length of the plunger 59 and the return speed of the servo piston 60.

This filling time is adjusted by appropriately setting the energization cutoff time of the solenoid coil 116, and the return speed of the servo piston 60 is adjusted by controlling the flow rate of the fuel oil from the servo piston chamber 76 through an orifice 89 provided in the fuel oil relief passage 94. It is adjusted by throttling the fuel appropriately. Furthermore, in this pump nozzle
7 can be made large in diameter, and since the valve seat 79 of the conical valve 61 is placed close to the servo piston chamber 76, fuel oil can be quickly introduced into the servo piston chamber 76, and the fuel can be quickly introduced into the servo piston chamber 76. It can be sprayed in a short time.

Furthermore, since a portion of the fuel oil is directly allowed to flow into the nozzle spring seat force hole 40, the mounting portion of the nozzle spring 36, which determines the opening pressure of the nozzle valve 32, can be made small and compact.

Further, since the oil flowing out from the conical valve chamber 84 is made to flow through the conical valve chamber outflow passage 165 formed at the axial center of the solenoid coil 116, the solenoid coil 116 is cooled by the oil flowing out, and the solenoid coil 116 is cooled. It is possible to prevent the suction ability from decreasing due to temperature rise, and the solenoid valve 111 can be operated more reliably.

Next, to explain the effects of the fuel injection device for an internal combustion engine of the present invention, the fuel injection device for an internal combustion engine of the present invention is a solenoid valve that is driven to open and close by a solenoid coil, and controls the back pressure of a conical valve that controls the operation of a servo piston. Since the solenoid valve is adjusted, the valve seat area of the solenoid valve can be reduced to use a solenoid with a small suction load, and the solenoid coil portion can be made smaller and lighter.

Furthermore, since the inlet of the servo piston chamber is opened and closed by a conical valve placed opposite to the inlet,
Ratio of change 4A in closing area A of servo piston chamber inlet to change in valve lift L of conical valve dA/
dL is the ratio dA/dS of the change dA in the inlet opening area A to the change dS in the stroke S of the slide valve when the slide valve 202 opens and closes the inlet 211 of the servo piston chamber as in the conventional example shown in FIG. This has the effect that the fuel oil can be introduced into the servo piston chamber more quickly, the fuel injection time can be shortened, and the fuel can be injected at a higher pressure.

In addition, since the fuel inlet of the conical valve chamber is always open and only the fuel outlet is opened and closed by the solenoid valve, only one valve seat needs to be polished for the solenoid valve and its seal. This has the effect of reducing costs by reducing the number of processing steps. Furthermore, if the fuel inlet of the conical valve chamber is formed in the conical valve itself as in the illustrated embodiment, the process for forming the inlet becomes easy and the number of processes can be reduced. This has the effect of simplifying the structure.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of an internal combustion engine having a fuel injection device according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a pump nozzle of the fuel injection device shown in FIG. Figure 4 is an enlarged view of the W part in Figure 2. Figure 5 is an enlarged view of the W part in Figure 2.
-V line sectional view of main parts, Figure 6 is a W arrow view in Figure 5, Figure 7 is a W-skin sectional view in Figure 6, Figure 8 is a skin-to-skin cross-sectional view in Figure 3, 9 is a cross-sectional view taken along the line KK in FIG. 3, FIGS. 10 and 11 are explanatory views of the operation of the pump nozzle in FIG.
1 and 13 are structural explanatory diagrams of a pump nozzle of a conventional fuel injection device. 18... Fuel supply pump, 20... Controller, 30... Injection nozzle section, 32...
・Nozzle valve, 55... pump section, 59... plunger, 60... servo piston, 61... conical valve, 76... servo piston chamber, 77... servo piston chamber inlet, 84... Conical valve chamber, 87...
...Servo piston chamber outlet, 105...Control unit, 111...Solenoid valve, 155...Conical valve chamber outlet, 156...Conical valve chamber inlet, X... ...Pump nozzle. Figure 2Figure 5Figure 3Figure 6Figure 7Figure 4Figure 8Figure 9Figure 12Figure 10Figure 13Figure 11

Claims (1)

[Claims] 1. A pump section 55 having a large-diameter servo piston 60 that is driven by a portion of the supplied fuel and a small-diameter plunger 59 that reciprocates in conjunction with the servo piston 60 to pump the fuel; and from the pump section 55. An injection nozzle section 30 having a nozzle valve 32 for injecting the high-pressure fuel oil to be sent.
a pump nozzle It is composed of a controller 20 for controlling the opening and closing of a solenoid valve 111 of the pump nozzle 76, the servo piston 60 is driven by the fuel pressure, and the fuel is injected from the injection nozzle part 30. A portion of the supplied fuel, which becomes the working oil for the servo piston 60, is transferred to the servo piston chamber 76 formed in the pump nozzle X.
A servo piston chamber inlet 77 for introducing the supplied fuel into the servo piston chamber 76 and a servo piston chamber outlet 87 for discharging the supplied fuel from the servo piston chamber 76 are provided. Conical valves 61 that open and close the inlet 77 are arranged opposite each other, and fuel oil is introduced into or discharged from the conical valve chamber 84 that accommodates the conical valve 61 to close the servo piston chamber inlet 77. Alternatively, the fuel inlet port 156 for introducing fuel oil into the conical valve chamber 84 is kept open at all times.
Further, by making the fuel outlet 155 of the conical valve chamber 84 have a larger passage area than the fuel inlet 156 and opening and closing the fuel outlet 155 with the solenoid valve 111, the fuel back pressure applied to the conical valve 61 is controlled. A fuel injection device for an internal combustion engine, characterized in that: