JP2000087821A - Injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize sharp cut and improve operational characteristics in an injection valve. SOLUTION: A needle 33 opening/closing an injection hole 31 is slidably retained in a cylinder 321. Back pressure to operate the needle 33 is generated by introducing high pressure from an in-orifice 39 and a hydraulic valve 4 relieving the high pressure of a first back pressure control chamber 38 is arranged in the first back pressure control chamber 38 so as to increase/decrease the back pressure. The hydraulic pressure of the hydraulic valve 4 is changed over by a solenoid valve 5. Hereby, the opening areas of the in-orifice 39 and hydraulic valve 4 can be increased regardless of the magnitude of the solenoid valve 5 and operational characteristics can be improved. The operating speed of the needle 33 is increased and sharp cup can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structural improvement for controlling the opening and closing of an injection valve.

[0002]

2. Description of the Related Art FIG. 4 shows a cross section of an injection valve used in a common rail type fuel injection system or the like. The injection valve 6 is provided with a nozzle portion 62 at the tip end of a rod-shaped housing 61, and injects a high-pressure fluid from an injection hole 621. A high-pressure passage 611 through which a high-pressure fluid flows is formed in the housing 61, and the tip thereof communicates with the injection hole 621. A needle 623 for opening and closing the injection hole 621 is slidably held in a cylinder 622 formed in the housing 61.
The seating on the valve seat 624 at the immediately upstream portion and the lift are switched.

[0003] Above the needle 623, a cylinder 622 is provided.
A back pressure control chamber 625 defined by a wall surface is formed, into which high pressure fuel is introduced as a control pressure from a high pressure passage 611 through an in orifice 626 to move the needle 623 downward, that is, in the valve closing direction with the force of the spring 627. Energizing back pressure is generated. The back pressure control chamber 625 is connected to a low pressure out passage 613 communicating with the drain passage 612, and relieves the high pressure in the back pressure control chamber 625. On the other hand, the tip surface 623a of the needle 623 and the step surface 623
b serves as a pressure receiving surface for high-pressure fuel, and the needle 623 is urged upward, that is, in the valve opening direction.

[0004] The valve opening and closing of the needle 623 is switched by controlling the high pressure relief of the back pressure control chamber 625 by the solenoid valve 63 which is a control pressure switching means to increase or decrease the pressure in the back pressure control chamber 625. Done. That is, when the solenoid valve 63 is “open”, the pressure in the back pressure control chamber 625 is relieved by the out passage 613, and at this time, the needle 623 assumes that the urging force in the valve opening direction is dominant. When the solenoid valve 63 is “closed”, the pressure in the back pressure control chamber 625 becomes high, and the urging force in the valve closing direction becomes dominant and the seat is seated.

[0005] US Patent No. 5,682,858 discloses a fuel injection valve in which a relief valve communicating with a sliding portion of a needle is provided to reduce oil hammer when the needle is opened and closed. In this fuel injection valve, a three-way valve is used as an electromagnetic valve, and when the back pressure of the needle is reduced and opened by operating the electromagnetic valve, the spool valve that restrains the relief valve is operated at the same time. Does not open the valve.

[0006]

Since the solenoid valve drives the valve body by means of a solenoid, the urging force of the control oil pressure applied to the valve body of the solenoid valve cannot be too strong to ensure stable and good operation. . Therefore, there is a limit in increasing the opening area of the solenoid valve. Therefore, the opening area of the in-orifice cannot be increased. For this reason, the rate of increase and decrease of the pressure in the back pressure control chamber was not sufficient, and good operating characteristics could not be obtained. That is, it takes a long time for the needle to be seated, and the sharp cut cannot be performed.

[0007] The present invention has been made in view of the above circumstances,
An object of the present invention is to provide an injection valve having good operating characteristics.

[0008]

According to the present invention, the back pressure of the needle generated in the back pressure control chamber is increased or decreased by controlling the high pressure relief of the back pressure control chamber to the low pressure outlet passage. A valve body for switching between communication and shutoff between the back pressure control chamber and the outlet passage, and an auxiliary back pressure control chamber for introducing control pressure through an auxiliary throttle to generate back pressure of the valve body. And a solenoid valve for controlling the relief of the high-pressure auxiliary outlet passage in the auxiliary back pressure control chamber.

Since the pressure in the back pressure control chamber is increased or decreased by a hydraulic control valve operated by an electromagnetic valve, the opening area on the low pressure side of the back pressure control chamber can be increased. Therefore, the opening area of the throttle for introducing the control pressure into the back pressure control chamber can be increased according to the opening area on the low pressure side. Therefore, the speed of increasing and decreasing the pressure in the back pressure control chamber can be increased, and as a result, the operating speed of the needle also increases, and the operating characteristics are improved. Therefore, a sharp cut can be realized.

In addition, since the operating speed of the needle does not indirectly depend on the increasing or decreasing speed of the pressure of the auxiliary back pressure control chamber for operating the valve element of the hydraulic operating valve, the increasing or decreasing speed of this pressure is defined. The opening area of the auxiliary throttle and the opening area of the solenoid valve may be relatively small. Therefore, a stable and favorable operation of the solenoid valve can be ensured, and the solenoid valve suffices to have low power consumption and a small shape.

In the invention described in claim 2, the hydraulic valve is configured so that the valve element linearly moves on the substantially same axis as the needle, and the solenoid valve is disposed substantially on the axis.

As described above, since the solenoid valve may be small, it is possible to reduce the size of the injection valve by adopting such a configuration.

According to the third aspect of the present invention, the valve body has a tip end projecting into the back pressure control chamber and facing an upstream end of the auxiliary outlet passage, and a high back pressure is applied to the valve body. The valve will be closed.

This makes it possible to prevent the back pressure control chamber and the auxiliary back pressure control chamber from communicating with the low pressure section via the sliding portion of the valve body when the pressure is high.

[0015]

FIG. 2 shows a configuration of a common rail type fuel injection system for a diesel engine to which the injection valve of the present invention is applied. The engine (not shown) is provided with a plurality of injection valves 11 corresponding to the combustion chamber of each cylinder. These injection valves 11 are connected to a common rail 13 common to the cylinders through a high-pressure fuel line 12, and high-pressure fuel as a high-pressure fluid is supplied from the common rail 13.
The injection valve 11 opens for a required time at a required time according to a command from an electronic control unit (ECU) 19 for controlling the entire system, and directly injects the high-pressure fuel stored in the common rail 13 into the combustion chamber. . Common rail 13
The fuel in the fuel tank 16 is pressurized and supplied by the high pressure pump 14 driven by the engine.

The pressure in the common rail 13 is detected by a pressure sensor 18 provided on the common rail 13,
The CU 19 adjusts the opening of the metering valve 15 upstream of the high-pressure pump 14 according to the shortage of the internal pressure of the common rail 13 and controls the internal pressure of the common rail 13 to a predetermined pressure value of 20 to 160 MPa. I have.

The fuel supplied from the common rail 13 to the injection valve 11 is used not only for injection into the combustion chamber but also as control oil for the injection valve 11, and from the injection valve 11 via a low-pressure drain line 17. The fuel is returned to the fuel tank 16.

FIG. 1 shows a cross section of the injection valve 11. Injection valve 1
Reference numeral 1 denotes a rod-shaped housing 2, which is provided with a nozzle 3, a hydraulic valve 4, and a solenoid valve 5 from below.

The housing 2 is provided at the upper end of the housing 2 with a high-pressure port 21 connected to the high-pressure fuel line 12 (FIG. 2) and a drain port 22 connected to the drain line 17 (FIG. 2). Also, inside the housing 2, the high-pressure fuel line 12
A high-pressure passage 23 communicating with the nozzle portion 3 is formed, and communicates with an injection hole 31 constituting the nozzle portion 3. In the high-pressure passage 23, high-pressure fuel from the common rail 13 (FIG. 2) flows, and is supplied for injection, and is supplied to the hydraulic valve 4 and the solenoid valve 5 as control oil as described later. A drain passage 24 communicating with the drain port 22 is formed inside the housing 2, so that low-pressure fuel flowing back to the drain line 17 flows from each part of the hydraulic valve 4 and the solenoid valve 5. ing.

The nozzle 3 will be described. The injection hole 31 is formed at a lower end of the housing 2 and faces a combustion chamber (not shown). Above the injection hole 31, a vertical hole 32 is formed along the axis C at approximately one third of the lower side of the housing 2. The upper half of the vertical hole 32 is a cylinder 321 in which the needle 33 is slidably held.
The needle 33 is a rod-like body with a step, and a large-diameter piston 3
32 comes into sliding contact with the cylinder 321, and the small-diameter nozzle needle 331 below the piston portion 332 is
Is housed in the lower half 321. Nozzle needle 33
The distal end of the valve body 3311 has a conical distal end surface 33 a, and a peripheral portion of the high pressure passage 23 immediately upstream of the injection hole 31 is seated as a valve seat 34.

When the needle 33 is closed, a control oil pressure acts on an annular portion above the abutting portion with the valve seat 34 except for the pointed portion, and the control oil pressure acts on the distal end surface 33a of the valve body portion 3311. The hydraulic pressure acts on the entire distal end surface 33a. The control oil pressure acting on the distal end surface 33a urges the needle 33 upward, that is, in the valve opening direction.

In the vertical hole 32, an enlarged diameter portion is formed at the step position of the needle 33, and the wall surface of the vertical hole 32 and the needle 33 are formed.
An annular oil reservoir 35 is formed between the peripheral wall surfaces. The oil reservoir 35 is always supplied with high-pressure fuel from the common rail 13, and when the needle 33 is opened, an annular gap between the wall surface of the vertical hole 32 and the peripheral wall surface of the nozzle needle 331,
The fuel is injected from the injection hole 31 through a gap between the distal end surface 33a of the valve body 3311 and the valve seat 34.

In the oil reservoir 35, high-pressure fuel acts on the downward step surface 33b of the needle 33 to urge the needle 33 upward, that is, in the valve opening direction.

The space defined by the wall surface of the cylinder 321 above the needle 33 is a spring chamber 37 for storing a spring 36. The spring 36 is disposed on the outer periphery of a spring guide 333 formed by a thin shaft-like projection of the needle 33, and urges the needle 33 downward, that is, in the valve closing direction.

The spring chamber 37 communicates with a first back pressure control chamber 38 as a back pressure control chamber via a communication passage 381, and
Fuel pressure as control oil pressure is introduced into the back pressure control chamber 38 from the high pressure passage 23 via an in-orifice 39 which is throttled. This fuel pressure acts on the upper end surface of the needle 33 to generate a back pressure that urges the needle 33 downward, that is, in the valve closing direction.

On the bottom wall surface of the first back pressure control chamber 38, a first out passage 2 which is an exit passage which is an upstream portion of the drain passage 24 is provided.
5 has an opening at the position of the axis C.

The hydraulically actuated valve 4 and the solenoid valve 5 constitute a control pressure increasing / decreasing means, and control the high pressure relief of the first back pressure control chamber 38 to the first out passage 25 so as to control the first back pressure. By increasing or decreasing the control pressure in the chamber 38, the urging force in the valve closing direction and the urging force in the valve opening direction are reversed to open and close the needle 33.

The hydraulic valve 4 is connected to the first back pressure control chamber 38 and the first
A cylinder 41 that opens and closes to the upper wall surface of the first back pressure control chamber 38 is formed in the housing 2 so as to switch between communication and blocking between the out passage 25. The cylinder 41 is formed along the axis C, and the cylinder 41 has a rod-shaped valve body 4.
2 is slidably held. The valve body 42 has a tip 42
1 projects into the first back pressure control chamber 38 and faces the upstream end of the first out passage 25. The diameter of the valve body 42 is set to be larger than the opening diameter of the upstream end of the first out passage 25. The valve body 42 has a distal end surface 42 a formed in a conical shape, and a peripheral portion of the upstream end of the out passage 25 is seated as a valve seat 43, and can shut off between the first back pressure control chamber 38 and the out passage 25. It has become.

When the valve body 42 is closed, the control oil pressure acts on the annular portion except for the pointed portion, and when the valve is opened, the control oil pressure acts on the entire end surface 42a. The control oil pressure acting on the distal end surface 42a is applied to the valve body 42.
In the upward direction, that is, in the valve opening direction.

A deep recess 422 is formed in the upper end surface of the valve body 42, and a spring 44 is housed in the recess 422. The spring 44 is interposed between the upper wall surface of the cylinder 41 and the bottom surface of the recess 422 in a compressed state, and urges the valve body 42 downward, that is, in the valve closing direction.

A space defined by the wall surface of the cylinder 41 above the valve body 42 is a second back pressure control chamber 45 serving as an auxiliary back pressure control chamber. A control oil pressure is introduced from the high pressure passage 23 through an orifice 46 serving as an auxiliary throttle, and the control oil pressure acts on the upper end surface of the valve element 42, and together with the spring 44, the valve element 4
2 is urged downward, that is, in the valve closing direction.

A communication passage 47 communicating with the second back pressure control chamber 45 along the axis C is formed in the housing 2. The solenoid valve 5 is provided between the communication passage 47 and the second out passage 26 which is an auxiliary outlet passage leading to the drain passage 24, and an upper end 471 of the communication passage 47 serves as an inlet of the solenoid valve 5. . The solenoid valve 5 controls the high-pressure relief of the second back pressure control chamber 45 to the second out passage 26. The communication passage 47 has a T-shaped branch formed in the middle thereof, and the control oil pressure is introduced from the orifice 46 into the second back pressure control chamber 45 through the branch.

The structure of the solenoid valve 5 is a general one, and the axis C
The armature 51 has a stepped rod-shaped armature 51 displaced along the axis and a valve body 52 displaced integrally therewith.
The upper end 471 is opened and closed. When the valve body 52 is lifted, the second back pressure control chamber 45 is closed by the communication passage 47 and the annular gap 5 formed on the outer periphery of the distal end of the armature 51.
3. The high pressure in the second back pressure control chamber 45 is relieved by communicating with the drain passage 24 via the second out passage 26.

A spring 55 disposed in a spring chamber 54 is provided above the armature 51 to urge the armature 51 downward, that is, in a valve closing direction.
2 is normally closed. A solenoid 56 is disposed on the outer periphery of the base of the armature 51, and when electricity is supplied to the solenoid 56, the armature 51 is suction-driven upward to lift the valve body 52.

That is, the solenoid valve 5 is connected to the second out passage 2
6, the control pressure in the second back pressure control chamber 45 is increased or decreased by controlling the high-pressure relief of the second back pressure control chamber 45 so that the urging force of the valve body 42 in the valve closing direction and the valve opening direction The biasing force is reversed to open and close the valve body 42.

Since the hydraulic valve 4 is operated by increasing or decreasing the control oil pressure as described above, there is no shortage of urging force to the valve element 42, such as a solenoid of an electromagnetic valve. Therefore, the diameter of the valve body 42 of the hydraulically operated valve 4 and the diameter of the first out passage 25 are made sufficiently large so that the opening area of the hydraulically operated valve 4 is made larger than the opening area of the solenoid valve 5. Is set to "open", the pressure reduction speed of the first back pressure control chamber 38 is increased. The opening area of the in-orifice 39 is also set to be sufficiently large according to the opening area of the hydraulically operated valve 4, and the first area when the hydraulically operated valve 4 is "closed".
The pressure increase speed of the back pressure control chamber 38 is increased.

The pressure reduction width of the second back pressure control chamber 45 required for the valve body 42 of the hydraulic valve 4 to start the lift is sufficiently large like the pressure reduction width of the first back pressure control chamber 38. No need. This is because the hydraulically actuated valve 4 is for increasing and decreasing the pressure of the first back pressure control chamber 38, and it is not necessary to consider prevention of erroneous injection unlike the needle 33. Therefore, the hydraulic valve 4
Can be operated with good responsiveness to the opening operation of the solenoid valve 5.

The operation of the injection valve 11 together with the operation of the entire common rail fuel injection system will be described. The ECU 19 outputs an energization command and an energization stop command to the solenoid valve 5 of the injection valve 11 at a predetermined timing, and fuel is injected from the injection hole 31 toward the combustion chamber during approximately this time.

FIG. 3 shows the change with time of each part of the injection valve 11.
FIG. 3A shows the current flowing through the solenoid valve 5, FIG. 3B shows the opening area of the solenoid valve 5, and FIG. 3C shows the second back pressure control chamber 45.
FIG. 3 (d) shows the opening area of the hydraulic valve 4, FIG.
3 (e) shows the pressure in the first back pressure control chamber 38, and FIG. 3 (f) shows the lift of the needle 33. In the figure, for comparison, FIG.
In the operation of the injection valve 6 having a structure in which the back pressure of the needle 623 is increased or decreased only by the solenoid valve 63 shown in FIG. 3, the current of the solenoid valve 63 is shown in the latter half of FIG. 3 (b), the pressure of the back pressure control chamber 625 is shown in the latter half of FIG. 3 (e), and the lift of the needle 623 is shown in the latter half of FIG. 3 (f). The injection valve 11 of the present invention
The solenoid valve 5 and the solenoid valve 63 and the nozzle part 3 and the nozzle part 62 of the injection valve 6 of the comparative example have basically the same specifications.

First, when the solenoid valves 5 and 63 are energized (FIG. 3A), the solenoid valves 5 and 63 are opened (FIG. 3B). There is virtually no difference in this operation.

In the conventional example, when the solenoid valve 63 is opened, the back pressure control chamber 625 and the out passage 64 communicate with each other, and the pressure in the back pressure control chamber 625 is changed according to the opening area of the solenoid valve 63. (E) in FIG. When the pressure reduction width of the back pressure control chamber 625 reaches a pressure reduction width necessary for the lift of the needle 623, the needle 623 starts lifting ((f) in FIG. 3), and fuel injection from the injection hole 621 starts. Is done.

On the other hand, in the present invention, when the solenoid valve 5 is opened, the second back pressure control chamber 45 communicates with the out passage 26, and the second back pressure control chamber 45 has the same hydraulic pressure as the high pressure passage 23 until then. The high pressure in the second back pressure control chamber 45 is relieved, and the pressure in the second back pressure control chamber 45 decreases ((c) in FIG. 3).

The valve body 42 of the hydraulically operated valve 4 has a distal end surface 42a.
The pressure of the first back pressure control chamber 38 is acting on the above annular portion, and when the valve body 42 is closed, the pressure of the first back pressure control chamber 38 is equal to the oil pressure of the high pressure passage 23.

When the pressure in the second back pressure control chamber 45 for urging the valve element 42 downwards decreases to a certain level, the force for urging the valve element 42 upward becomes dominant, and the valve element 42 is lifted. Then, the hydraulically operated valve 4 is opened (FIG. 3 (d)). Since the volume of the second back pressure control chamber 45 can be made relatively small, the decompression speed is high, and the hydraulic valve 4 is opened at a high timing.
Becomes

As a result, the first back pressure control chamber 38 and the first out passage 25 communicate with each other to relieve the high pressure in the first back pressure control chamber 38, and the pressure in the first back pressure control chamber 38 decreases (FIG. 9). 3
(E)). Although the pressure in the first back pressure control chamber 38, that is, the pressure acting on the distal end surface 42a of the valve body 42, decreases,
Since the pressure receiving surface expands from the annular portion of the distal end surface 42a to the whole, the valve body 42 maintains the lift state. In the present invention, since the opening area of the hydraulic valve 4 can be increased, the pressure in the first back pressure control chamber 38 decreases at a high speed. And the pressure reduction width of the first back pressure control chamber 38 corresponds to the needle 3
When the decompression width required for lifting the needle 3 is reached, the needle 3
3 starts the lift (FIG. 3 (f)), and the injection of fuel from the injection hole 31 is started. Since the pressure reduction width required for the needle 33 to lift is basically the same as the conventional example,
When the lift of the needle 33 is started, the hydraulic valve 4 is opened.
Later, it is done at a quick timing.

Thus, after the solenoid valve 5 is energized, the needle 33 starts lifting at a quick timing. Thus, according to the present invention, the needle lift response time (t1) for energizing the solenoid valve can be made shorter than the needle lift response time (t1 ') for energizing the solenoid valve in the conventional example.
Demonstrate excellent operation response.

Next, the operation when the valve is closed will be described. Solenoid valve 5,
When the power supply to the solenoid 63 is turned off (FIG. 3A), the solenoid valves 5 and 6 are turned off.
3 is "closed" (FIG. 3 (b)). At this time, there is substantially no difference in operation response between the present invention and the conventional example.

In the conventional example, the solenoid valve 63 is closed.
As a result, the back pressure control chamber 625 and the out passage 64
Is shut off again, and the pressure in the back pressure control chamber
3 (e) in FIG. 3, the needle 623 descends and sits on the valve seat 624 ((f) in FIG. 3), and the injection of fuel from the injection hole 621 stops. I do.

On the other hand, in the present invention, the second back pressure control chamber 45 and the second out passage 26 are shut off when the solenoid valve 5 is closed. On the other hand, the second back pressure control chamber 45
High-pressure fuel flows from the high-pressure passage 23 through the orifice 46, the pressure in the second back-pressure control chamber 45, which has been lower than that in the high-pressure passage 23, rises (FIG. 3).
(C)).

When the pressure in the second back pressure control chamber 45 rises to the above-mentioned level, the force for urging the valve element 42 downward becomes dominant, and the valve element 42 starts lowering, and the hydraulically actuated valve The opening area of No. 4 is reduced (FIG. 3 (d)). On the other hand, since high-pressure fuel flows into the first back pressure control chamber 38 from the high-pressure passage 23 via the in-orifice 39, the first
The pressure in the back pressure control chamber 38 increases ((e) in FIG. 3). Then, when the urging force for pushing down the needle 33 becomes more dominant than the urging force for pushing up the needle 33, the needle 33 starts to descend. Thereafter, the needle 33 is seated on the valve seat 34 ((f) in FIG. 3), and the injection of fuel from the injection hole 31 is stopped.

In the present invention, since the opening area of the in-orifice 39 can be increased, a sufficiently high pressure is introduced from the high-pressure passage 23, the pressure in the first back pressure control chamber 38 rises at a high speed, and the needle 33 moves quickly. At the same time, it descends at a high speed.

As described above, according to the present invention, the time (t3 ') from when the needle 33 is lifted to the seated state is shorter than the time (t3) from when the needle 623 is seated from the lifted state in the conventional example. And sharp cut can be realized. As a result, the needle sitting response time (t2) for turning off the solenoid valve can be shorter than the needle sitting response time (t2 ') for turning on the solenoid valve in the conventional example.

As described above, according to the present invention, excellent operation characteristics are exhibited. In addition, the solenoid valve 5 suffices to have low power consumption and a small shape.

Further, since the needle 33 and the valve body 42 are moved linearly along the axis C, and the small electromagnetic valve 5 is arranged on the axis C, the injection valve 11 can be made slimmer.

The valve element 42 has a tip 421 protruding into the first back pressure control chamber 38, and is opposed to the upstream end of the first out passage 25. Because the back pressure is applied to close the valve, the first
The back pressure control chamber 38 and the second back pressure control chamber 45 are prevented from communicating with the drain passage 24 which is a low pressure part via a clearance (sliding part) between the valve body 42 and the cylinder 41 when the pressure is high. Can be.

The configuration of the injection valve of the present invention is not limited to the above-described embodiment, and is arbitrary as long as it does not contradict the gist of the present invention. For example, depending on the required specifications of the injection valve, it is not necessary to adopt a configuration for achieving the slimness of the injection valve 11, and for example, the hydraulically operated valve and the solenoid valve may be arranged off-axis. When the pressure is high, the first back pressure control chamber 38 and the second back pressure control chamber 45 communicate with the drain passage 2 via the clearance between the valve body 42 and the cylinder 41.
For example, the valve body of the hydraulically operated valve has a distal end projecting into the back pressure control chamber and facing the upstream end of the outlet passage. The valve may be closed when the pressure is low.

Although this embodiment has been described as applied to a common rail fuel injection system, the present invention can be applied to other uses.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of an injection valve of the present invention.

FIG. 2 is a configuration diagram of a common rail type fuel injection system to which the injection valve of the present invention is applied.

FIG. 3 is a time chart showing the operation of the injection valve of the present invention in comparison with a conventional example.

FIG. 4 is a sectional view showing an example of a conventional injection valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Injection valve 2 Housing 23 High-pressure passage 24 Drain passage 25 1st out passage (outlet passage) 26 2nd out passage (auxiliary exit passage) 3 Nozzle part 31 Injection hole 321 Cylinder 33 Needle 38 First back pressure control chamber (Back pressure) Control room) 39 In-orifice (throttle) 4 Hydraulic valve (control pressure increasing / decreasing means) 42 Valve body 45 Second back pressure control chamber (auxiliary back pressure control chamber) 46 Orifice (auxiliary throttle) 5 Solenoid valve (control pressure increasing / decreasing means) ) C axis

Claims (3)

[Claims] 1. A needle which is slidably held in a cylinder and opens and closes an injection hole through which a high-pressure fluid is injected, and a back pressure control chamber for introducing a high control pressure through a throttle to generate a back pressure of the needle. And a low-pressure outlet passage connected to the back pressure control chamber and relieving the high pressure in the back pressure control chamber, and controlling the high-pressure relief to the outlet passage to increase or decrease the control pressure in the back pressure control chamber to move the needle. In the injection valve having a control pressure increasing / decreasing means for opening and closing, the control pressure increasing / decreasing means includes a valve body for switching between communication and shutoff between the back pressure control chamber and the outlet passage, and a control pressure via an auxiliary throttle. A hydraulically actuated valve having an auxiliary back pressure control chamber for generating a back pressure of the valve element, a low pressure auxiliary outlet passage connected to the auxiliary back pressure control chamber and relief of the high pressure of the auxiliary back pressure control chamber, High pressure lily to auxiliary outlet passage And a solenoid valve for controlling the valve. 2. The injection valve according to claim 1, wherein the hydraulically operated valve has a structure in which the valve body linearly moves on substantially the same axis as the needle, and the solenoid valve is disposed substantially on the axis. Injection valve. 3. The injection valve according to claim 1, wherein the valve body has a distal end projecting into the back pressure control chamber and facing an upstream end of the auxiliary outlet passage. An injection valve configured to be closed by application of the back pressure.