JPH0988756A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce electric power consumption by restraining temperature rise of a solenoid and to improve durability of the solenoid by branching and supplying a part of high pressure fuel supplied to an injection device from a high pressure fuel source at the time of energizing the solenoid to drive a valve member of a directional control valve. SOLUTION: When a solenoid 76 is energized by a control device 126 in an intermediate region of an engine, for example, at the time of low speed and an intermediate and high load, a valve member 74 is made to rise to a position to make contact with a lower surface of a solenoid core 112, and a communicating passage 90 communicated through to a fuel supply passage 88 is communicated through to a pressure chamber 58 through a supply oil passage 92, etc. Thereafter, when high pressure fuel is supplied to the fuel supply passage 88, a piston 64 is pressed down, and a needle valve is energized in the closing direction. Additionally, at this time, high pressure fuel regulated in quantity through an orifice 94 flows to a branch oil passage 98, passes a low pressure chamber 108 from a valve spring chamber 96 and flows to a passage for cooling through a slit of an armature 118, and accordingly, the solenoid 76 is effectively cooled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid injection device, and more particularly to a fluid injection device suitable for use in a fuel injection device of a diesel engine.

[0002]

2. Description of the Related Art In a fuel injection device for a direct injection type diesel engine, a first injection hole having a small total injection hole cross-sectional area that operates when the engine operates at a low speed and a relatively large injection hole that operates when the engine operates at a high speed. A first needle valve for controlling opening / closing of the first nozzle hole and a second needle valve for controlling opening / closing of the second nozzle hole in a nozzle body having a second nozzle hole having a nozzle hole cross-sectional area. A device accommodating substantially parallel to each other is German Patent Publication DE 4115478A1 (publishing date: 1
(November 21, 991).

[0003] The fuel injection device disclosed in the above-mentioned German Patent Publication (hereinafter, referred to as a proposed fuel injection device in some cases) uses a first injection hole having a small total injection hole cross-sectional area during low speed operation of the engine. Fuel can be injected at a high injection pressure, and at the time of high-speed operation of the engine, fuel can be injected at a high injection pressure from the second injection hole having a large total injection hole cross-sectional area. There is an advantage that engine performance can be improved, such as stable combustion, reduction of idle noise, improvement of smoke performance and improvement of fuel efficiency.

The above proposed fuel injection system includes a first needle valve for opening and closing the first low speed injection hole and a second needle valve for opening and closing the second high speed injection hole according to the operating state of the engine. A switching valve device is provided as means for selectively actuating one of the needle valves and hydraulically locking the other in an inoperative state by utilizing the pressure of the high-pressure fuel. A solenoid that operates as an electromagnetic actuator for driving the valve member.

During operation of the engine, the solenoid of the switching valve device generates heat when energized, and therefore needs to be cooled. However, in the above proposed fuel injection device, in order to prevent the seizure of the idle needle valve, the return fuel that has become hot due to cooling of the needle valve is provided in the solenoid housing containing the solenoid. Although it is configured to be cooled by flowing in the leak-off passage, the solenoid is not sufficiently cooled because the temperature of the return fuel is high. Therefore, the continuous operation of the engine may cause the temperature of the solenoid to rise considerably, and the higher the temperature, the more the electric resistance increases. Therefore, the calorific value further increases and the power consumption increases. There is a drawback that is damaged.

[0006]

SUMMARY OF THE INVENTION The present invention was devised in view of the above circumstances and comprises a first needle valve and a second needle valve that selectively operate according to the operating state of the engine, and should be operated as described above. A fuel injection device that uses a solenoid as an actuator that drives a valve member of a switching valve device that locks or locks a needle valve to be inactivated by hydraulic pressure of high-pressure fuel while selecting a needle valve, When the solenoid is energized, a part of the relatively high temperature high pressure fuel supplied from the high pressure fuel source to the injector is branched and positively cooled as a cooling medium to suppress the temperature rise of the solenoid. The main purpose is to reduce power consumption and improve the durability of the solenoid.

[0007]

To achieve the above object, the present invention provides a nozzle body having a first nozzle hole and a second nozzle hole, which communicate with a common fuel reservoir, at a tip portion facing the combustion chamber of an engine. And a fuel supply passage provided in the nozzle body and a nozzle holder connected to the nozzle body for guiding fuel from a high-pressure fuel source to the fuel reservoir, and slidable in the nozzle body facing the fuel reservoir. A first needle valve and a second needle valve, which are opened and closed to respectively open and close the first injection hole and the second injection hole.
A needle valve, a first pressure spring and a second pressure spring that are housed in the nozzle holder and elastically bias the first needle valve and the second needle valve in the closing direction, respectively, and are formed in the nozzle holder. Further, the first pressure chamber and the second pressure chamber are slidably accommodated respectively, and fuel is supplied to the first pressure chamber and the second pressure chamber from the fuel supply passage. A first piston and a second piston for urging the two-needle valve in the closing direction in cooperation with the first pressure spring and the second pressure spring, respectively;
A valve member that communicates the fuel supply passage and the first pressure chamber at the first position and communicates the fuel supply passage and the second pressure chamber at the second position. A solenoid for displacing the solenoid valve from the first position to the second position, and a switching valve having a return spring for holding the valve member at the first position when the solenoid is deenergized. A fuel injection device is provided which is provided with a branch oil passage for guiding fuel from the fuel supply passage to the cooling passage of the solenoid when in the second position.

In the present invention, the first needle valve and the second needle valve are disposed substantially parallel to each other in the nozzle body, and the first and second pistons are the first needle valve and the second needle valve.
The first needle valve and the first needle valve are arranged substantially coaxially with the needle valve.
The first pressure spring is arranged at an axially intermediate portion of the piston, the second pressure spring is arranged at an axially intermediate portion of the second needle valve and the second piston, and the first pressure spring is arranged at the first and second pistons. It is preferable that the valve member of the switching valve is arranged at a portion opposite to the first and second pressure springs substantially parallel to each piston. Further, it is preferable that a branch oil passage in the switching valve is connected to an oil passage in the switching valve that communicates the fuel supply passage with the second pressure chamber via a metering orifice. Further, it is preferable that the first injection hole is composed of a injection hole group having a small total injection hole cross-sectional area, and the second injection hole is formed of an injection hole group having a large total injection hole cross-sectional area.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments in which the present invention is applied to a fuel injection device for a direct injection type diesel engine will be specifically described with reference to the accompanying drawings. Prior to the explanation
FIG. 1 is a vertical cross-sectional view of the upper half portion of the fuel injection valve generally indicated by reference numeral 10, and FIG. 2 is a vertical cross-sectional view of the lower half portion of the same cross section of the fuel injection valve. Therefore, by adding FIG. 1 to the upper part of FIG. 2, one fuel injection valve is completed.
Similarly, FIG. 3 is a vertical cross-sectional view of an upper half portion along different cut surfaces (surfaces in a direction perpendicular to the cut surfaces of FIGS. 1 and 2) of the fuel injection valve, and FIG. 4 is different. It is a longitudinal cross-sectional view of the lower half along the cut surface. In the figure, reference numeral 10 generally indicates a fuel injection valve, and the injection valve 10 is a nozzle body 12
And a distance piece 14 and a nozzle holder 16, and the nozzle body 12 and the nozzle holder 16 are
The distance piece 14 is sandwiched in the middle, and is tightened by a retaining nut 18 to be integrally connected.

The nozzle body 12 is provided with a first injection hole 20 for injecting fuel and a second injection hole 22 at one end portion facing the combustion chamber of each cylinder of an engine (not shown). The first injection hole 20 and the second injection hole 22 are respectively provided in plurality (two or more, usually 4 to 7), and the total injection hole cross-sectional area of the first injection hole 20 is the second injection hole. It is formed smaller than the total cross-sectional area of 22 injection holes.

Further, in the nozzle body 12, a first needle valve 24 for opening and closing the first injection hole 20 and a second injection hole 22.
And a second needle valve 26 that opens and closes the first needle valve 24 and the second needle valve 26 are substantially parallel to each other, and the first needle valve 24 and the second needle valve 26 face a common fuel reservoir 28 formed in the nozzle body 12. 24 '
And 26 ', respectively. The fuel reservoir 28 communicates with cylindrical fuel passages 30 and 32 formed around the outer peripheries of the first and second needle valves 24 and 26, respectively. It communicates with the first injection holes 20 and 22, respectively, via valve seat portions 34 and 36 which cooperate with the conical valve surface. Inside the nozzle holder 16, cylindrical first spring chambers 40 and 42 are provided coaxially with the first and second needle valves 24 and 26, respectively.

A first pressure spring 46 is accommodated in the first spring chamber 40 via upper and lower spring retainers 44a and 44b, and the first pressure spring 46 causes the first needle valve 24 to move to the valve seat portion 34. It presses elastically against it. On the other hand, the second spring chamber 42 is composed of a small-diameter upper spring chamber 42a and a large-diameter lower spring chamber 42b which are coaxially formed. The upper spring chamber 42a includes upper and lower spring retainers 48a and 4a.
The first-stage pressure spring 50 is contracted via 8b, and the second needle valve is provided via the first-stage pressure spring 50 and a retainer rod 48c that extends downward from the lower spring retainer 48b at all times. 26 is elastically pressed against the cooperating valve seat portion 36. Also,
Inside the lower spring chamber 42b, a second-stage pressure spring 54 is contracted via upper and lower spring retainers 52a and 52b. The second stage of the pressure spring 54, the second needle valve 26, as shown in FIGS. 2 and 4, was increased to overcome the pressure spring 50 of the first stage only lift 1 ₁ of the first stage activated later, allowing the lift 1 ₂ of the second stage of Dohariben 26. The first
The stepped pressure spring 50 and the second stepped pressure spring 54 constitute a second pressure spring that controls the lift of the second needle valve 26.

As best shown in the upper half sectional view of FIG. 1, in the nozzle holder 16, coaxial with the first needle valve 24 and the first spring chamber 40, and the second needle valve 26.
First and second pressure chambers 56 and 58 are arranged coaxially with the second and second springs 42, respectively.
6 and 58 are formed in a cylinder element 60. A first piston 62 is slidably fitted in the first pressure chamber 56, and a second piston 64 is fitted in the second pressure chamber 58.
Are slidably fitted. The first piston 62 and the second piston 64 have the first and second needle valves 2 respectively.
Push rods 62 'and 6 in line with 4 and 26
4'is made integrally or separately and is fixed to each piston by press fitting or screwing. The push rods 62 'and 64' have their lower end surfaces at the upper end surface of the lower spring retainer 44b in the first spring chamber and the lower spring retainer 48 in the second spring chamber, respectively.
It abuts on the upper end surface of b.

In the nozzle holder 16, a switching valve generally designated by the numeral 66 is arranged above the cylinder element 60. The switching valve 66 includes a lower valve housing 70a fitted in a valve insertion hole 68 in the nozzle holder 16 and an upper valve housing 70b fixed to the upper end of the valve insertion hole 68 by screwing. A cylindrical valve housing 70, a valve member 74 formed of a spool valve slidably fitted in a valve cylinder 72 of the valve housing 70, and a solenoid 76 as an electromagnetic actuator for driving the valve member 74 are provided. It has the above-mentioned valve member 7
4 has an axis parallel to the axes of the first needle valve 24 and the second needle valve 26.

The first pressure chamber 56 and the second pressure chamber 5 are provided between the valve housing 70 and the cylinder element 60.
A plate 82 having passages 78 and 80 respectively communicating with the upper end of 8 is provided, and in the valve housing 70, one end communicates with the passage 78 and the other end has an inner peripheral surface of a lower portion of the valve cylinder 72. There is provided a first oil passage 84 which is open to the above, and a second oil passage 86 whose one end communicates with the passage 80 and whose other end is opened to an upper portion of the valve cylinder 72. Further, in the valve housing 70, a supply oil passage 92 that is always in communication with a communication passage 90 that intersects a fuel supply passage 88 formed in the nozzle holder 16 and one end of the second oil passage 86 via an orifice 94. A branch oil passage 98 is provided which communicates with the valve cylinder and has the other end opened to a valve spring chamber 96 provided in an upward extension of the valve cylinder 72.

In the valve spring chamber 96, the valve member 7
4 through the spring receiving flange or the spring retainer 100 protruding from the outer periphery of the valve 4, the valve member 74 is always in the rest position shown in FIG. 1 (the spring receiving flange 100 is in contact with the shoulder portion 102 of the valve housing. The return spring 104 that is elastically pressed against the position (in which the position is) is housed. On the other hand, the valve member 74 has an annular groove 106 on the outer peripheral surface that selectively communicates the supply passage 92 with either one of the first oil passage 84 and the second oil passage 86 by its vertical displacement.
A drain oil passage 110 is provided to connect the other of the first oil passage 84 and the second oil passage 68 to the low pressure chamber 108 via the valve spring chamber 96.

The low pressure chamber 108 is provided at the center of a solenoid core 112 that cooperates with the solenoid 76, and the valve member 7 is provided.
4 is communicated with a cooling passage 114 provided coaxially therewith, and the cooling passage 114 is communicated with an appropriate low-pressure fuel source such as a leak-off passage of a fuel injection pump (not shown). In addition, the valve member 74 is inserted into the low pressure chamber 108 by the bolt 116.
A disk-shaped armature 118 fixed to the upper end of the is housed. As best shown in the plan view of FIG. 7, the armature 118 includes a plurality (six in the case shown) of radially extending slits 120.
20 is a passage for guiding the fuel from the low pressure chamber 108 to the cooling passage 114.

The fuel supply passage 88 has one end connected to a high-pressure fuel source such as a fuel injection pump (not shown), and the other end connected to the first and second needle valves as well shown in FIG. Two
Common fuel reservoir 2 facing 4 and 26 or surrounding both needle valves
Connect to 8. Further, the solenoid 76 is, as schematically shown only in FIG. 1, an output signal Ne of the rotation speed sensor 122 for detecting the rotation speed of the engine and an accelerator opening for detecting the accelerator pedal depression amount indicating the load of the engine. It is controlled by a control unit or controller 126 which receives the output signal Ac of the frequency sensor 124 and produces a drive output. The control unit or control device 1
26 has a built-in control map shown in FIG. 8 (a torque diagram in which the horizontal axis represents the engine speed Ne and the vertical axis represents the output torque Tq). In the operating region A and the low speed / low load region A ′, the solenoid 76 is de-energized, and the intermediate region B (that is, low speed / medium / high load, medium speed / low, medium / high load, and high speed / low load). At the time), the solenoid 76 is energized.

In the above fuel injection system, the cross-sectional view of the main part of FIG. 5 shows a state where the engine is operating in the operating region A or A'in the map of FIG. 8 and the solenoid 76 is deenergized. At this time, the valve member 74 of the switching valve 66 is held at the illustrated lowered position by the return spring 104. Due to the downward displacement of the valve member 74, the fuel supply passage 88
A communication passage 90 communicating with the oil supply passage 92 and the annular groove 10.
6, and communicates with the first pressure chamber 56 via the first oil passage 84 and the passage 78. Therefore, when high-pressure fuel is supplied to the fuel supply passage 88 from a high-pressure fuel source such as a fuel injection pump, the first piston 62 is pressed downward, and the push rod 62 is moved to the first position.
The lower spring retainer 44b in the spring chamber 40 is pressed downward and cooperates with the first pressure spring 46 to bring the first needle valve 24 into pressure contact with the valve seat portion 34.
Therefore, the high-pressure fuel supplied from the high-pressure fuel source to the fuel reservoir 28 through the fuel supply passage 88 is the step portion 24 ′ of the first needle valve 24.
Even if the needle valve is pressed in the opening direction, that is, upward, by acting on, the needle valve is not opened.

On the other hand, the second pressure chamber 58 has a passage 80, a second
The high pressure fuel does not act on the second piston 64 because it communicates with the low pressure fuel source through the oil passage 86, the oil discharge passage 110 in the valve member 74, the valve spring chamber 96, the low pressure chamber 108 and the cooling passage 114. . Therefore, when the high-pressure fuel is supplied from the high-pressure fuel source to the fuel reservoir 28 through the fuel supply passage 88, the pressure of the high-pressure fuel acting on the second needle valve 26 causes the first
Been overcome two of the pressure spring 50 of the first stage of the spring constituting the pressure spring, the second needle valve 26 is made the initial injection only open lift 1 _1, then In conjunction to the increase in fuel supply pressure The second-stage pressure spring 54 is overcome and the second needle valve 26 is lifted.
₂ is opened further and injection is performed.

By injecting fuel from the second injection holes 22 having a large total injection hole cross-sectional area as described above, the initial combustion is suppressed, especially in the low load operation region A'including the idle operation, so that the combustion is performed. The operation noise mainly including the noise is effectively reduced, and in the high rotation and high load operation region A, the initial combustion is suppressed and the gentle combustion is performed to change the combustion pressure, increase the maximum combustion pressure and the temperature. Is suppressed and the generation of NO _X is effectively suppressed. At this time, the solenoid 76 is deenergized,
Of course, it does not need to be actively cooled because it does not generate heat.

Next, when the engine is operating in region B of FIG. 8, the solenoid 76 is energized by the control unit or controller 126. When the solenoid 76 is energized, as shown in FIG. 6, the armature 1
18 is sucked and the valve member 74 moves up to a position where it abuts the lower surface of the solenoid core 112. Due to the upward displacement of the valve member 74, the communication passage 90 communicating with the fuel supply passage 88 is
Supply oil passage 92, annular groove 106, second oil passage 86, passage 80
Since it is communicated with the second pressure chamber 58 via the second pressure chamber 58, when the high pressure fuel is supplied from the high pressure fuel source to the fuel supply passage 88,
The piston 64 is pressed down and urges the second needle valve 26 in the closing direction in cooperation with the first stage pressure spring 50 via the push rod 64 'and the rod 48c of the lower spring retainer 48b. Therefore, even if high-pressure fuel is supplied to the fuel reservoir 28, the second needle valve 26 will not open.

As described above, since the fuel supply passage 88 and the second oil passage 86 communicate with each other, the high-pressure fuel metered through the orifice 94 flows into the branch oil passage 98, and the valve spring chamber 96 to the low-pressure chamber. The gas flows through the slit 120 of the armature 118 to the cooling passage 114, and further to the low pressure fuel source. It is not the fuel after cooling the idle needle valve as in the previously proposed fuel injection device, but the relatively low temperature sufficient amount of high pressure fuel metered by the orifice 94 from the fuel supply passage 88. , Solenoid 76
Is positively cooled, the solenoid 76 that is energized and generates heat is effectively cooled, and an increase in electric resistance is prevented. Therefore, an increase in power consumption is suppressed, and its durability and reliability are improved. improves.

On the other hand, the upward displacement of the valve member 74 causes the first
The pressure chamber 56 communicates with the oil discharge passage 110 via the passage 78 and the first oil passage 84, and further includes the valve spring chamber 96 and the low pressure chamber 1.
08 to communicate with the cooling passage 114. The fuel pressure reduced by the orifice 94 is applied to the valve spring chamber 9
6 acts on the first piston 62 in the first pressure chamber 56 via the oil discharge passage 110 and the first oil passage 84. However, since the fuel pressure is sufficiently low, the high pressure fuel is supplied to the fuel sump 28. As a result, the first pressure spring 46 is overcome to open the first needle valve 24, and fuel is injected at a sufficient injection pressure from the first injection hole 20 having a small total injection hole cross-sectional area. As a result, good combustion is ensured, sufficient engine performance is exhibited, and exhaust gas performance is improved and operating noise is reduced.

According to the fuel injection device of the present invention, the needle valve which is inactive among the first and second needle valves 24 and 26 is switched in order to lock the inoperative state by the fuel pressure. Since the amount of fuel oil supplied from the valve 66 to the first or second pressure chamber 56 or 58 is small, and the amount of fuel oil existing in the passage 30 or 32 around the needle valve which is at rest is also small, There is no deterioration in disconnection at the end of injection, and there is no risk of problems due to back leakage.

Further, compared with the previously proposed fuel injection device, the fuel supply passage 88 and the cooling passage / fuel discharge passage 1 provided in the nozzle body 12 and the nozzle holder 16 are provided.
A cylinder element 66 having a small number of fourteen and a short passage length, and further including components such as a valve housing 70 and a valve member 74 of the switching valve 66, an armature 118, and first and second pressure chambers 56 and 58 is a nozzle. Since the holder 16 can be easily assembled, it can be manufactured at a significantly low cost. Further, the first and second needle valves 24 and 26 are arranged substantially parallel to each other and each needle valve 24
And 26, coaxially with the first and second pressure spring chambers 40 and 42, and in parallel with the axes of the first and second needle valves 24 and 26, the switching valve 66.
Since the valve insertion hole 68 for accommodating the nozzle, and thus the valve member 74, is provided, the nozzle body and the nozzle holder 16 can be easily drilled, and the manufacturing cost can be further reduced.

In the above embodiment, the second needle valve 26 that opens and closes the second injection hole 22 is lifted in two stages by the first and second stage pressure springs 50 and 54. Similar to the first needle valve 24, it can be changed to a normal needle valve whose lift is controlled by a single pressure spring.

[0028]

As described above, in the fuel injection device according to the present invention, the nozzle body having the first injection hole and the second injection hole communicating with the common fuel reservoir is provided at the tip end portion facing the combustion chamber of the engine. And a fuel supply passage provided in the nozzle body and a nozzle holder connected to the nozzle body for guiding fuel from a high-pressure fuel source to the fuel reservoir, and slidable in the nozzle body facing the fuel reservoir. And a first needle valve and a second needle valve, which are opened and closed respectively to open and close the first injection hole and the second injection hole,
A first pressure spring and a second pressure spring that are housed in the nozzle holder and elastically bias the first needle valve and the second needle valve in the closing direction, respectively, and a first pressure formed in the nozzle holder. Are slidably housed in the chamber and the second pressure chamber, respectively, and fuel is supplied to the first pressure chamber and the second pressure chamber from the fuel supply passage, whereby the first needle valve and the second needle valve are opened. A first piston and a second piston that cooperate with the first pressure spring and the second pressure spring to urge them in the closing direction, respectively, and a first piston thereof.
The fuel supply passage communicates with the first pressure chamber at the position, and the fuel supply passage communicates with the second pressure at the second position.
A valve member that communicates with the pressure chamber, a solenoid that is biased to displace the valve member from the first position to the second position, and a return that holds the valve member at the first position when the solenoid is deenergized. A switching valve having a spring, the switching valve being provided with a branch oil passage for guiding fuel from the fuel supply passage to the cooling passage of the solenoid when the valve member is in the second position. The solenoid as an actuator for driving the switching valve is positively cooled by the fuel of a relatively low temperature introduced from the branch oil passage when energized, so that the power consumption of the solenoid is small, and It has the advantage of excellent durability and reliability.

Further, the branch oil passage in the switching valve is connected to the oil passage in the switching valve which connects the fuel supply passage and the second pressure chamber via the metering orifice. There is an advantage that the solenoid can be cooled surely and effectively by ensuring a sufficient controlled flow rate of the cooling fuel. Further, the first needle valve and the second needle valve are arranged substantially parallel to each other in the nozzle body, and the first and second pistons are substantially coaxial with the first needle valve and the second needle valve. And the first pressure spring is disposed at an axially intermediate portion of the first needle valve and the first piston, and the second pressure spring is disposed at an axially intermediate portion of the second needle valve and the second piston. And the first
With the configuration in which the valve member of the switching valve is arranged substantially parallel to each piston on the portion of the second piston opposite to the first and second pressure springs, a large number of holes are formed in the nozzle body and nozzle holder. There is an advantage that processing and assembling work of the switching valve can be facilitated and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an upper half portion of a fuel injection device according to the present invention.

2 is a cross-sectional view showing a lower half portion of the fuel injection device shown in FIG.

FIG. 3 is a cross-sectional view of an upper half portion in different cross sections of the fuel injection device shown in FIG.

4 is a sectional view of a lower half portion of the fuel injection device shown in FIG.

5 is a sectional view of relevant parts showing a state when a solenoid 76 of the fuel injection device shown in FIG. 1 is deenergized.

FIG. 6 is a cross-sectional view of essential parts showing a state where a solenoid of the fuel injection device shown in FIG. 1 is energized.

7 is a plan view showing an extracted armature 118 in FIG. 1. FIG.

8 is a diagram showing an example of a solenoid control map built in a control unit or control device 126 in FIG.

[Explanation of symbols]

10 ... Fuel injection valve, 12 ... Nozzle body, 14 ... Distance piece, 16 ... Nozzle holder, 18 ... Retaining nut, 20 ... First injection hole, 22 ... Second injection hole, 24 ... First needle valve, 26 ... Second needle valve, 28 ... Fuel reservoir, 40 ... First spring chamber, 42 ... Second spring chamber, 46 ... First pressure spring, 50 ... First stage pressure spring, 54 ... Second stage pressure spring, 56 ... Second 1 pressure chamber, 58 ... 2nd pressure chamber, 62 ... 1st piston, 64 ...
2nd piston, 62 '... push rod, 64' ... push rod, 66 ... switching valve, 70 ... valve housing, 74
... Valve member, 76 ... Solenoid, 84 ... First oil passage, 86 ...
Second oil passage, 88 ... Fuel supply passage, 90 ... Communication passage, 92
Supply oil passage, 94 Orifice, 98 Branch oil passage, 10
4 ... Return spring, 106 ... Annular groove, 110 ... Oil discharge passage, 112 ... Solenoid core, 114 ... Cooling passage, 118 ... Armature, 126 ... Control unit or control device.

Claims (4)

[Claims] 1. A nozzle body having a first injection hole and a second injection hole, which communicate with a common fuel reservoir, at a tip portion of the engine facing the combustion chamber, the nozzle body, and a nozzle holder connected to the nozzle body. A fuel supply passage provided in the nozzle body for guiding fuel from a high-pressure fuel source to the fuel reservoir; and a fuel supply passage slidably accommodated in the nozzle body facing the fuel reservoir and including the first injection hole and the second injection hole. First needle valve and second needle that open and close respectively
A needle valve, a first pressure spring and a second pressure spring that are housed in the nozzle holder and elastically bias the first needle valve and the second needle valve in the closing direction, respectively, and are formed in the nozzle holder. Further, the first pressure chamber and the second pressure chamber are slidably accommodated respectively, and fuel is supplied to the first pressure chamber and the second pressure chamber from the fuel supply passage. A first piston and a second piston for urging the two-needle valve in the closing direction in cooperation with the first pressure spring and the second pressure spring, respectively;
A valve member that communicates the fuel supply passage and the first pressure chamber at the first position and communicates the fuel supply passage and the second pressure chamber at the second position. A solenoid for displacing the first position to the second position, and a switching valve having a return spring for holding the valve member at the first position when the solenoid is deenergized. A fuel injection device, characterized in that a branch oil passage is provided for guiding fuel from the fuel supply passage to the cooling passage of the solenoid when in the second position. 2. The first nozzle hole is composed of a nozzle hole group having a small total nozzle hole cross-sectional area, and the second nozzle hole is composed of a nozzle hole group having a large total nozzle hole cross-sectional area. The fuel injection device according to claim 1. 3. A branch oil passage in the switching valve is connected to an oil passage in the switching valve that connects the fuel supply passage and the second pressure chamber via a metering orifice. The fuel injection device according to claim 1, which is characterized in that. 4. The first needle valve and the second needle valve are arranged substantially parallel to each other in a nozzle body, and the first and second pistons are arranged with respect to the first needle valve and the second needle valve. The first pressure spring is disposed substantially coaxially, the first needle valve and the first piston are axially intermediate in the axial direction, and the second needle valve and the second piston are axially intermediate in the second axial direction.
The pressure spring is arranged, and the valve member of the switching valve is arranged at a portion of the first and second pistons opposite to the first and second pressure springs substantially parallel to the pistons. The fuel injection device according to claim 1 or 2, which is characterized in that.