JPH02176157A - Pressure intensifying fuel injection device - Google Patents

Abstract

PURPOSE:To reduce vibration and noise generated at the time of combustion by providing a change-over valve with throttle parts for opening an operating oil feed passage at the small opening area by displacement of the change-over valve from the first position to the second position. CONSTITUTION:On the periphery of a land 21b, there are provided plural cutout parts 50, which intercommunicates a large diameter hole 22c with a large diameter hole 22b across a small diameter hole 22f by displacement of a spool valve 21, and thus serves as throttle parts for opening an operating oil feed passage at the small opening area. When the valve 21 is displaced further to the right until the left end side peripheral surface 21b coincides with the small diameter hole 22f, the operating oil feed passage once opened at the small opening is closed again. The operating oil feed passage is thus once opened at the small opening area by displacement of the valve 21 from the first position to the second position, then closed, and further opened to the full, so that pilot injection can be positively performed prior to main injection, and thus vibration and noise generated at the time of combustion can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pressure increase type fuel injection device equipped with a pressure increase mechanism for injecting fuel at high pressure.

(Prior Art) Conventionally, such a pressure increase type fuel injection device is disclosed in, for example, Japanese Patent Laid-Open No. 154854/1983. That is, this conventional technology includes a nozzle section, a pressure increasing mechanism that increases the pressure of fuel supplied into a fuel supply chamber and sends it to the nozzle section, and a hydraulic oil that supplies hydraulic oil to a pressure receiving surface of the pressure increasing mechanism. A switching valve is provided that is displaceable between a first position that closes the supply passage and a second position that fully opens the supply passage, and an electromagnetic valve that seals the switching valve ψ, and the switching valve is in the second position. When the displacement occurs, the pressure in the fuel supply chamber is increased by the pressure increasing mechanism, and the fuel is injected at high pressure. On the other hand, in fuel injection devices used in diesel engines, in order to reduce vibration and noise generated during combustion, a small amount of fuel is injected into the combustion chamber when the piston enters the compression period and the fuel can be ignited. Various techniques have been proposed in which a large amount of fuel is injected into the combustion chamber at once (main injection) after the pilot injection.

(Problem to be Solved by the Invention) However, in the conventional technology equipped with the above-mentioned pressure increase mechanism, the switching valve can only close and fully open the hydraulic oil supply path, and the switching valve is in the first position of OQ. When the pressure increasing mechanism is displaced from the position to the second position, a large amount of hydraulic oil acts on the pressure receiving surface of the pressure increasing mechanism, causing the pressure increasing mechanism to displace through its entire stroke.
The pressure of the fuel in the fuel supply chamber is increased by the pressure increase mechanism,
Since fuel for personnel is injected all at once at high pressure, the pilot injection cannot be performed. Therefore, vibrations and noise generated during combustion become large.

The present invention has been made by focusing on these conventional problems, and is a pressurized fuel type fuel that can perform pilot injection with a simple configuration, thereby reducing vibration and noise generated during combustion. The purpose is to provide an injection device.

(Means for Solving the Problems) In order to achieve the above object, the pressure boosting fuel injection device according to the present invention includes a nozzle portion and an increaser that increases the pressure of the fuel supplied into the fuel supply chamber and feeds the fuel under pressure to the nozzle portion. a switching block that is displaceable between a first position that closes a hydraulic oil supply passage for supplying actuation '/111 to a pressure receiving surface of the pressure mechanism and a second position that fully opens the supply passage; P, wherein when the switching valve is displaced to the second position, the pressure in the fuel supply chamber is increased by the pressure increasing mechanism and the fuel is injected at high pressure. The switching valve is provided with a throttle portion that opens the hydraulic oil supply passage by a small opening area during displacement from the first position to the second position.

(Function) In the above-mentioned pressure boosting type fuel injection device, the throttle portion operates (4) while the Zino exchange valve is displaced from the first position to the second position.
1 When the supply channel is opened with a small opening area, a small amount of hydraulic oil acts on the pressure receiving surface of the pressure increase mechanism, slowly displacing the pressure increase mechanism, thereby increasing the pressure of the fuel in the fuel supply chamber and sending it to the nozzle. A pilot injection is performed by injecting a small amount of fuel. After this pilot injection, when the switching valve moves to the second position and the hydraulic oil supply path is fully opened, a large amount of hydraulic oil acts on the pressure receiving surface of the pressure booster piston, rapidly displacing the pressure increase mechanism, and this causes the fuel The remaining fuel in the supply chamber is pressurized and sent to the nozzle section, and a large amount of fuel is injected at once to perform main injection.

(Example) Hereinafter, each embodiment of this research will be described based on the accompanying drawings.

Note that in each embodiment, the same parts are given the same reference numerals and redundant explanations will be omitted.

FIG. 1 is a longitudinal cross-sectional view showing a pressure boosting type fuel injection device according to a first embodiment of the present invention. A metering section 3 that measures the fuel pumped from the device into the fuel supply chamber 2 to the required amount for each injection, and an increaser that increases the pressure of the fuel supplied into the fuel supply chamber 2 and pumps it to the nozzle section A. This is a pressure increasing unit injector in which a control section B including a pressure mechanism 4 is integrally constructed. Each pressure boosting unit injector 1 is installed in each cylinder head of a diesel engine, respectively.

As shown in FIG. 1, the nozzle portion Δ is composed of a nozzle body 5 having a nozzle hole (not shown) at the tip, a spacer 6, and a nozzle holder body 7, which are integrally fastened with a retaining nut 8. ing.

The nozzle body 5 includes a central hole 5b that communicates with a nozzle hole (not shown) and has a fuel inflow chamber 5a formed in the center, and a fuel inflow chamber 5.
A passage 5C communicating with a is formed. Central hole 5b
In the figure, the side valve 9 is fitted so as to be slidable between the closed position shown in the figure and the opened position displaced above the closed position. Each of the four valves 9 is formed with a pressure receiving surface 9b that receives the pressure of the fuel being pumped into the fuel inflow chamber 5a.

The spacer 6 has a shaft portion 9a protruding from the end of the needle valve 9.
A through hole 6a through which the nozzle body 5 passes, and a passage 6b communicating with the passage 5c of the nozzle body 5 are formed.

The nozzle holder main body 7 has a spring chamber 7a for accommodating a nozzle spring 11 that biases the needle valve 9 toward the valve closing position via a movable spring seat 1O, and a passage 6b of the base 6 communicates with the spring chamber 7a. A passage 7b is formed.

The control section B includes a first main body section 13 to which an inlet connector 12 is screwed, to which fuel at a constant pressure is fed under pressure from the fuel supply device (not shown) through a pipe (not shown), and a pressure increasing mechanism 4. Cylinder bore 1 into which piston 14 is slidably fitted
5a and the third main body part 17 are fastened together with a bolt 18, and the fourth main body part 20 to which the solenoid valve 19 is attached is attached to the left end surface of the first main body part 13 by a bolt (not shown). It is concluded and consists of. Then, the third main body part 17 and the nozzle holder main body 7 are connected with the retaining nut 16.
By tightening them, a pressure-increasing unit injector 1 in which the control ff11B and the nozzle part A are integrated is configured. Note that each joint surface of the main body portion 13°, 15, 17, and 20 is oil-tightly sealed.

A spool valve (switching valve) 21 is provided in the first main body portion 13 . When the spool valve 21 is in the first position shown in FIG.
The fuel F) supply path for supplying fuel under pressure to the input boat 1-13b into the fuel supply chamber 2 is opened, and the fuel under pressure to be conveyed to the input boat 1-13b is transferred to the pressure receiving surface (increase) of the pressure boosting piston 14. The hydraulic oil supply path for supplying hydraulic oil to the pressure receiving surface (14a) of the pressure machine groove 4 is closed, and when it is displaced rightward from the first position to the second position, the fuel supply path is closed and i;
Fully open the hydraulic oil supply path.

The spool valve 21 is slidably fitted into a shaft hole 22 that passes through the first main body portion 13 in the lateral direction.

The shaft hole 22 has a large diameter hole 22a opened in the left end surface of the first body part 13 and a hydraulic oil chamber 15b formed in the upper part of the pressure booster piston 14 through an outlet boat 13c. A large-diameter hole 22b that communicates with a fuel tank (not shown) on the low-pressure side through the shown passage and piping, and an inlet boat 13b.
A large diameter hole 22c communicating with the fuel passage 13d, a large diameter hole 22d communicating with the fuel passage 13d, and a screw hole 22e opening on the left end surface of the first main body part 13 are formed. A spring receiver member 23 is screwed into the screw hole 22e, and a spring 24 is inserted into the spring receiver member 23 to force the spool valve 21 toward the first position.
is interposed. The screw hole 22e and the spring receiver are connected to the member 23.
The joint surfaces are oil-tightly sealed. And the fuel passage of the spool valve 21! 3d communicates with the fuel supply chamber 2 via a fuel passage 15c of the second body part 15, a check valve 25 provided in the third body part 17, and a fuel passage 17a.

The spool valve 21 has a land 21a of the same diameter that is slidably fitted into a small diameter hole 22f of the shaft hole 22.

21b, 21c, and small diameter portions 21d, 21e, 21f are formed. When the spool valve 21 is in the first position, the land 21b separates from the small diameter hole 22f between the large diameter holes 22c and 22d (see FIG. 1), thereby causing the land 21b to separate from the large diameter hole 22c. 22d, while the land 21b closes the small diameter hole 22f between the large diameter holes 22c and 22b.
, thereby closing the hydraulic oil supply path from the large diameter hole 22c to the large diameter hole 22b. Further, when the spool valve 21 is displaced to the second position 011, the land 21
b closes the small diameter hole 22f between the large diameter holes 22c and 22d and closes the fuel supply path, and the land 21b separates from the small diameter hole 22f between the large diameter holes 22c and 22b (see FIG. 3). d)), thereby fully opening the hydraulic oil supply path. Furthermore, the land 21b
A small diameter hole 2 between the large diameter holes 22c and 22b is formed on the outer periphery of the spool valve 21 while the spool valve 21 is displaced from the first position to the second position.
A third hole straddles 2f and communicates both large diameter holes 22c and 22b.
(see FIG. 3(b)), thereby opening the hydraulic oil supply path with a small opening area (a plurality of notches 50 are provided as throttle portions), and the spool valve 21 opens as shown in FIG. 3(b).
When the land 21b is further displaced to the right and the left end side outer circumferential surface 21b' of the land 21b matches the small diameter hole 22f, the hydraulic oil supply path that was once opened by a small opening is closed again. .

The pilot oil pressure controlled by the solenoid valve 19 is the fourth
When acting on the end of the small diameter portion 21d that is slidably fitted into the fitting hole 20a of the main body portion 20, the spool valve 21
is adapted to be displaced rightward from the first position to the second position.

The casing 30 of the electromagnetic valve 19 is fixed to a passage forming member 32 that is press-fitted onto the inner circumference of a mounting ring 31 . By inserting the abutment plate 33 deep into the mounting hole 20b of the fourth main body part 20 and screwing the male threaded part of the mounting ring 3 into the female threaded part of the mounting hole 20b, the solenoid valve 19 is attached to the fourth main body part 20. It is attached to the section 20. When the solenoid valve 19 is off, as shown in FIG. 1, the armature 34 is separated from the solenoid coil 35 by the (; At this time, the third main body part 17, the fourth main body part 20, the abutment handle 33, and each passage +3e in the passage forming member 32.

mj entry robot 1 via 20b, 33a and 32a
Large diameter hole 32b in passage forming member 32 communicating with 3b
and each passage 3 in the passage forming member 32 and the abutting plate 33.
The land 3G of the valve stem 36 communicates with the large diameter hole 32d which communicates with the pilot hydraulic chamber 38 via 2c and 33b.
n, thereby allowing the pilot hydraulic chamber 38
Fuel is not supplied from the inlet boat 13b, and the pilot oil pressure is 11? It is configured not to act on the end portion of the small diameter portion 21d. Also, when the solenoid valve 19 is on, the second
As shown in the figure, the armature 34 is attracted to the electromagnetic coil 35 against the biasing force of the spring 37, and the valve stem 36 is displaced to the right. At this time, the large diameter hole 32b in the passage forming member 32
and 32d communicate with each other, whereby the pilot hydraulic chamber 3
8, and the pilot oil pressure is applied to the small diameter part 21d.
It is designed to act on the end of the

In this manner, while the solenoid valve 19 is off, the supply of fuel 1-1 from the fuel supply device to the pilot hydraulic chamber 38 is stopped, and the pressure of fuel t1 is maintained at the end Ifμ of the small diameter portion 21d. does not act as pilot 40 pressure, and as a result, the spool valve 21 is biased by the spring member 24 and held at the first position. When the solenoid valve 19 is turned on, fuel is supplied into the pilot hydraulic chamber 38 and the small diameter section A pilot oil pressure acts on the end of the spool valve 21d, thereby causing the spool valve 21 to move rightward from the first position to the second position.

The pressure increase mechanism 4 includes a pressure increase screw I/N 14 having a large pressure receiving portion 14a, and a plunger 41 slidably fitted into a press-fit hole 40 formed in the third main body portion 17. . When fuel from the fuel supply device is supplied as hydraulic oil into the hydraulic oil chamber 15b, the pressure intensifier groove 4 lowers the pressure intensifier piston I4 from the -up position to the lowered position shown in FIG. push down the plunger 41, thereby filling the insertion hole 4.
The fuel previously supplied into the fuel supply chamber 2 formed at the lower end of the plunger 41 is compressed by being pressed by the lower end surface of the plunger 41, and the pressure is increased. The fuel in the fuel supply chamber 2 whose pressure is increased by lowering the plunger 41 in this way is
While the horizontal passage 41a' of the T-shaped passage 41a provided at the tip of the plunger 41 so as to communicate with the fuel supply chamber 2 communicates with the large diameter hole 40a of the insertion hole 40, the passage 41
a and the passageway of the third main body portion 17 via the large diameter hole 40 a +
7b. The passage 17b communicates with the passage 7b in the nozzle holder 7, and carries the increased pressure of the fuel';
A passage 7b and the passages 6b and 5c together form a pressure passage for feeding the fuel into the inflow chamber 5a.

The insertion hole 40 is provided with a large diameter hole 40b that communicates with a fuel tank (not shown) on the low pressure side via one passage 17c and a pipe (not shown).

Further, the connecting portion between the passages 17b and 7b communicates with the fuel tank, which is the low pressure side, via the passage +7d, the discharge [117e], and a pipe (not shown).

Furthermore, the spring chamber 7a marked 111j in the nozzle holder 7 is
The side valve 9 is communicated with the fuel tank via a passage 7c that communicates with the passage 17d so that the side valve 9 is not hydraulically locked and quickly rises.

The operation of the first embodiment having the above configuration will be explained below.

When the solenoid valve 19 is off, as shown in FIG. The communication between the large diameter hole 32t) and 32d is cut off by the land 36a of the valve stem 36. by this,
The supply of fuel from the fuel supply device to the pilot hydraulic chamber 38 is stopped, and the pilot hydraulic pressure does not act on the end of the small diameter portion 21d of the spool valve 21, and the spool valve 21 is biased by the spring member 24. is held in the first position.

While the spool valve 21 is in the first position, the land 21b closes the small diameter hole 22f between the large diameter holes 22c and 22b of the shaft hole 22 (see FIGS. 1 and 3(a)), thereby The hydraulic oil supply path from the large diameter hole 22c to the large diameter hole 22b is closed, and fuel from the fuel supply device is not supplied to the hydraulic oil chamber 15b located above the pressure boosting piston I4. On the other hand, while the spool valve 21 is in the first position, the land 21b is in the large diameter hole 2.
2c and 22d (see FIG. 1), thereby opening a fuel supply path from the large diameter hole 22c to the large diameter hole 22d, and the fuel from the fuel supply device flows into the fuel supply path. , fuel passages 13d, +5c, check valve 25, and fuel passage 17a. When fuel is supplied into the fuel supply chamber 2, the hydraulic oil chamber 15
b communicates with the fuel tank, which is the low-pressure side, via the outlet port 13c, the large-diameter hole 22b, and passages and piping (not shown), so that the pressure booster piston 14° and the plunger 41 in the lowered position shown in FIG. is returned to the 2-up position by fuel pressure.

? When the Ilt magnetic valve 19 is turned on, as shown in FIG.
The armature 34 is attracted to the electromagnetic coil 35 and the valve stem 36
is displaced to the right, the large diameter holes 32b and 32d in the passage forming member 32 communicate with each other, and the pilot? 111 pressure is small diameter part 21
d, thereby causing the spool valve 21 to
displacement to the right from the position to the second position.

When the spool valve 21 is displaced rightward from the first position to the second position, first, the outer peripheral surface of the right end side of the land 21b fits into the small diameter hole 22f between the large diameter holes 22c and 22d. The fuel supply path is then closed, thereby completing the metering of the fuel supplied into the fuel supply chamber 2. At this time, land 21b
is in the position shown in Fig. 3(a), and its outer peripheral surface is the large diameter hole 22.
c and 221), and closes the hydraulic oil supply path.

When the spool valve 21 is further displaced to the right from the position shown in FIG. 3(a) and reaches the position shown in FIG. Both large diameter holes 22c straddle the small diameter hole 22f.

22b, whereby the hydraulic oil supply path is connected to the fourth
It opens with a small opening area as shown by the curve Ap representing the opening area in the figure. At this time, the fuel pumped from the fuel supply device is transferred to the hydraulic oil supply path with a small opening area, that is, the notch 50.
The pressure increasing piston 14 receives the hydraulic oil and slowly descends while pushing down the plunger 41. Due to this descent, the fuel in the fuel supply chamber 2 is compressed and increased in pressure, and a small amount of the increased pressure is transferred to the T-shaped passage 41a and the large diameter hole 40.
a, and further passages 17b, 7b.

The fuel inflow chamber 5a passes through the pressure feeding passage consisting of 6b and 5c.
pumped inside. When the fuel pressure in the fuel inlet chamber 5a reaches the valve opening pressure, the needle valve 9 rises from the closed position shown in FIG. 1, thereby opening the injection hole and injecting a small amount of fuel at high pressure. This injection is the injection shown by the injection rate curve 1p in FIG.

When the spool valve 21 is further displaced to the right from the position shown in FIG. 3(b) and reaches the position shown in FIG. 3(c), the land 21b
The left end side outer circumferential surface 21b' matches the small diameter hole 22f, and the hydraulic oil supply path, which was opened with a small opening area, is closed again (section Ao in FIG. 4). This allows the hydraulic oil to flow into the hydraulic oil chamber 15.
The pressure boosting piston 14 and the plunger 41 are temporarily stopped at a position on the way down, and the pressure feeding of fuel into the fuel inflow chamber 5a is stopped. As a result, when the fuel pressure in the fuel inflow chamber 5a decreases to below the valve opening pressure, the needle valve 9 descends from the valve opening position to the valve opening position and the pilot injection ends (see A in FIG. 5).

Department).

When the spool valve 21 is further displaced to the right from the position shown in FIG. 3 (C) and reaches the position (second position) shown in FIG.
The hydraulic oil supply path, which was previously closed, is fully opened (section Am in FIG. 4). As a result, a large amount of hydraulic oil is supplied into the hydraulic oil chamber 15b through the fully opened hydraulic oil supply path.
The pressure boosting piston 14, which has received the hydraulic oil, rapidly descends to the lowered position shown in FIG. 1 while pushing down the plunger 41.

This lowering compresses and increases the pressure in the fuel supply chamber 2, and a large amount of the increased pressure is fed into the fuel inflow chamber 5a, causing the fuel pressure in the fuel inflow chamber 58 to reach the valve opening pressure. When the injection hole is reached, the needle valve 9 rises again from the closed position shown in FIG. 1 to open the injection hole, and a large amount of fuel is injected at once at high pressure. This injection is the main injection shown by the injection rate curve Im in FIG.

In this way, according to the first embodiment, the spool valve 21
During the displacement from the first position to the second position, the hydraulic oil supply passage is first opened with a small opening area, then the hydraulic oil supply passage is scooped out, and then the supply passage is fully opened. , pilot injection can be reliably performed before main injection.

Further, in the first embodiment, the spool valve 21 is the solenoid valve 1.
9, the spool valve 21 is configured to be displaced from the first position to the second position when the pilot oil pressure controlled by the solenoid valve 19 acts on the end of the spool valve 21. It is made. And spool valve 2
1 is in the first position and the fuel supply passage is open, the pressure of the fuel passing through the supply passage acts on each opposing side surface of the lands 21b and 21G of the spool valve 21, but the lands 21b and 21c have the same diameter, so the forces pushing the spool valve 21 left and right are balanced. Therefore, since the pilot oil pressure for displacing the spool valve 21 from the first position to the second position may be small, the solenoid valve 19 that controls this small pilot oil pressure can be configured in a small size.
9 is attached to the control section B and the nozzle section.
The pressure boosting unit injector, which has a physical structure of h11, can be made smaller and the power consumption can be reduced.

Next, a second embodiment of the present invention will be described.

The pressure increase type fuel injection device 1 according to the second embodiment differs from that of the first embodiment only in the portion indicated by the symbol C in FIG. 6.

That is, in the pressure increase type fuel injection device l of the second embodiment, while the spool valve 21 is displaced from the first position to the second position, the hydraulic fluid supply path is opened as a constriction portion with a small opening area. Instead of the notch 50, a stepped portion 60 is provided between the land 21b and the small diameter portion 21e of the spool valve 21.

Therefore, in this second embodiment, when the spool valve 21 is displaced rightward from the first position to the second position, the land 21b
When it leaves the small diameter hole 22f between the large diameter holes 22c and 22d, both large diameter holes 22c pass through the annular space between the small diameter hole 22f and the stepped portion 6o.

22b communicates with each other, thereby connecting the hydraulic oil supply path to the seventh
It opens with a small opening area as shown by the curve Ap representing the opening area in the figure. At this time, the fuel fed under pressure from the fuel supply device is squeezed through the hydraulic oil supply path with a small opening area, that is, the annular space between the small diameter hole 22f and the stepped portion 60, and is stored as hydraulic oil in the hydraulic oil chamber 15b. Therefore, similarly to the first embodiment, the pressure increasing screw 14 that receives the hydraulic oil slowly descends while pushing down the plunger 41 to increase the pressure of the fuel in the fuel supply chamber 2, and this increase occurs. A small amount of pressurized fuel is forced into the fuel inflow chamber 5a, and the small amount of fuel is injected at high pressure (pilot injection is performed).At this time,
Since the hydraulic oil supply path is open with a small opening area, the pressure booster piston 14 and the plunger 41 slowly descend to force the fuel from the fuel supply chamber 2 into the fuel inflow chamber 5a. Since the amount is small, the injection causes the fuel pressure in the fuel inflow chamber 5a to drop below the valve opening pressure.

This ends the pilot injection.

When the spool valve 21 is further displaced to the right and the stepped portion 60 is separated from the small diameter hole 22f between the large diameter holes 22c and 22d, it is moved through the annular space between the small diameter hole 22f and the small diameter r+++ 21e. Both large diameter holes 22c, 221) communicate with each other, n
The hydraulic oil supply path iJ is fully opened without being closed once (section Am in FIG. 7). As a result, a large amount of fuel is injected at once at high pressure (main injection is performed), similarly to the first embodiment.

In each of the above embodiments, the pressure boosting fuel injection device l is configured as a pressure boosting unit injector in which the nozzle section A and the control section B are integrated, but the present invention is not limited to this. Part B may be separate.

(Effects of the Invention) As described in detail above, the pressure boosting fuel injection device according to the present invention includes a nozzle section, a pressure boosting mechanism that increases the pressure of the fuel supplied into the fuel supply chamber, and pressure-feeds it to the nozzle section. , a switching valve movable between a first position that closes a hydraulic oil supply passage for supplying hydraulic oil to the pressure receiving surface of the pressure increasing mechanism and a second position that fully opens the supply passage; When the switching valve is displaced to the second position, in the pressure boosting type fuel injection device in which the pressure of fuel in the fuel supply chamber is increased by the pressure increasing mechanism and injected at high pressure, the switching valve is moved from the first position to the second position. The switching valve is provided with a constriction part that opens the hydraulic oil supply passage with a small opening area while the switching valve is displaced from the first position to the second position. When the passage is opened with a small opening area, a small amount of hydraulic oil acts on the pressure receiving surface of the pressure increase mechanism, slowly displacing the pressure increase mechanism, thereby increasing the pressure of the fuel in the fuel supply chamber and pumping it to the nozzle part. , a small amount of fuel is injected and a pilot injection is performed,
After this pilot injection, when the switching valve moves to the second position and the hydraulic oil supply path is fully opened, a large amount of hydraulic oil acts on the pressure-receiving surface of the pressure booster groove, rapidly displacing the pressure booster mechanism, and this causes the fuel The remaining fuel in the supply chamber is pressurized and sent to the nozzle section, and a large amount of fuel is injected at once to perform main injection.

Therefore, pilot injection can be performed with a simple configuration, thereby making it possible to reduce vibrations and noise generated during combustion, and increase the output of the machine W1.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention. FIG. 1 is a vertical cross-sectional view showing a pressure boosting fuel injection device when the solenoid valve is off, and FIG. 2 is a diagram when the solenoid valve is turned off. A cross-sectional view when it is on, Figures 3 (a) to (d) are action explanatory diagrams, Figure ff14 is a graph showing the relationship between the spool valve stroke and the opening area of the hydraulic oil supply path, and Figure 5 is the cam angle. FIG. 6 is a longitudinal cross-sectional view showing the main parts of the pressure boost type fuel II injection device according to the second embodiment of the present invention, and FIG. 7 is a graph showing the spool valve stroke and the hydraulic oil supply path. 1 is a graph showing the relationship between the area and the area. Fig. 3 A... Nozzle part, ■... Pressure boost type fuel injection device, 2.
... Fuel supply chamber, 4... Pressure increasing mechanism, 14a... Pressure receiving surface of pressure increasing piston (pressure receiving surface of pressure increasing machine +15't), 21
... Spool valve (switching valve), 50... Notch part (throttle part), 60... Step part (throttle part).

Claims (1)

[Claims] 1. a nozzle section, a pressure increasing mechanism that increases the pressure of fuel supplied into the fuel supply chamber and pressure-feeds it to the nozzle section, and a first valve that closes a hydraulic oil supply path for supplying hydraulic oil to a pressure receiving surface of the pressure increasing mechanism.
and a switching valve that is displaceable between a position and a second position that fully opens the supply passage, and when the switching valve is displaced to the second position, the pressure of the fuel in the fuel supply chamber is increased by a pressure increasing mechanism. In the pressure increase type fuel injection device that injects at high pressure, the switching valve is provided with a constriction portion that opens the hydraulic oil supply passage with a small opening area while the switching valve is displaced from the first position to the second position. A pressure increase type fuel injection device characterized by: