JPH07145763A - Solenoid valve for fuel injection device regulation - Google Patents

Abstract

PURPOSE:To provide a solenoid valve for fuel injection device regulation capable of freely setting formation of a fuel passage, and being assembled easily. CONSTITUTION:An electromagnetic spill valve 32 is provided with a fuel passage 34 communicating a pressure chamber flow passage 30 inside a fuel injection pump with a low pressure chamber flow passage 36, a spool 54 for shutting this passage by being inserted in the fuel passage 34 and bringing a taper-shaped seat face 80 in tight contact with the valve seat part 78 inside the fuel passage 34, and a stopper 56 slidably inserted into the axial part 54a of the spool 54 projected from the fuel passage 34. Consequently, an armature 58 provided on the top end of the axial part 54a and sucked upward by an electromagnet 62, and a first spring 66 for energizing the armature 58 downward from the electromagnet 62 side, and a second spring 68 provided between the armature 58 and the stopper 56, and having larger energizing force than that of the first spring 66 are provided. By this constitution, handling of the injection passage 34 becomes free, and assembling is also simplified.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metering solenoid valve for a fuel injection device, and more particularly to a metering solenoid valve for connecting and disconnecting a high pressure chamber and a low pressure chamber in the fuel injection device.

[0002]

2. Description of the Related Art Conventionally, as a solenoid valve for metering of this kind, a high pressure chamber for supplying pressurized fuel to a fuel injection valve, which is used in a distributed fuel injection pump of a diesel engine, is provided from the outside. There is an electromagnetic spill valve that opens and closes the low pressure chamber in response to a control signal. This electromagnetic spill valve is a fuel passage that connects the high-pressure chamber and the low-pressure chamber, and moves in the fuel passage, and the seat surface formed at the end is brought into close contact with the valve seat portion in the fuel passage to close the valve. The valve body to shut off this passage, the valve opening spring that urges the valve body in the valve opening direction, and the valve body is closed by suctioning the valve body against the urging force of the valve opening spring. And an electromagnet that causes the movement. Then, when the fuel injection is started, the valve is closed to shut off the high pressure chamber and the low pressure chamber, so that the fuel in the high pressure chamber can be injected from the fuel injection valve. On the other hand, when the fuel injection amount reaches a predetermined value, the valve is opened and the high pressure chamber and the low pressure chamber are communicated with each other, whereby the fuel in the high pressure chamber is released to the low pressure chamber and the fuel injection is stopped.

Therefore, with respect to this type of solenoid valve for metering, the stroke of the valve body when the valve is closed is set small in order to ensure responsiveness at the start of fuel injection, while the valve body when the valve is opened. The strokes are required to be set large in order to improve the fuel injection cutoff, and the contradictory characteristics are required.

Therefore, conventionally, as a solenoid valve for metering of this kind, as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-262059, at the tip of the valve body when the electromagnet is not excited (when the valve is open). It has been proposed that a restricting member that abuts and restricts the valve opening amount of the valve element is biased by a spring in the valve closing direction of the valve element.

In the conventional metering solenoid valve thus constructed, when the pressure in the high pressure chamber is high, that is, when the valve is opened during fuel injection, a large pressure in the high pressure chamber and the low pressure chamber is generated. Since the force in the valve opening direction is applied to the valve body due to the difference, the restricting member in contact with the valve body moves in the valve opening direction against the biasing force of the spring. Therefore, the valve opening amount of the valve body becomes large, and the fuel injection can be quickly ended.
On the other hand, when the pressure in the high pressure chamber is small, that is, before the fuel injection is started, the biasing force of the spring provided in the regulating member is greater than the force applied to the valve body due to the pressure difference between the high pressure chamber and the low pressure chamber. The valve opening amount of the valve body is regulated to a predetermined value, and the responsiveness at the time of closing the valve at the start of fuel injection is ensured.

[0006]

However, in the above-described conventional metering solenoid valve, the valve opening spring and the regulating member spring are provided at both ends of the valve body, respectively. One of the springs must be provided in the fuel passage or at a position that complicates the shape of the fuel passage, which restricts the handling of the fuel passage and has a problem that the assemblability is poor. .

The present invention has been made in view of the above problems, and provides a solenoid valve for metering a fuel injection device in which the shape of the fuel passage can be freely set and which can be easily assembled. With the goal.

[0008]

SUMMARY OF THE INVENTION That is, the present invention, which has been made to achieve the above object, provides a fuel passage for connecting a high pressure chamber and a low pressure chamber in a fuel injection device, and a fuel passage provided in the fuel passage. A valve body which has a tapered seat surface, and closes the fuel passage by bringing the seat surface into close contact with a valve seat portion provided in the fuel passage; A shaft portion that extends in a direction in which the valve body closes and protrudes from the fuel passage, an armature provided at an end portion of the shaft portion opposite to the valve body, and the shaft portion of the armature are opposite to each other. And an electromagnet for attracting the armature to close the valve body by being excited, and a first urging means for urging the armature from the electromagnet side in a direction in which the valve body opens. Means and between the fuel passage and the armature. Comprises a second biasing means for biasing said armature to the magnet side, and in normal the first
The seat surface of the valve element is arranged within a predetermined proximity range to the valve seat portion of the fuel passage by the urging force of the urging means and the urging force of the second urging means. The gist is a solenoid valve for metering the fuel injection device.

[0009]

In the metering solenoid valve of the fuel injection device of the present invention configured as described above, the valve body having the tapered seat surface is the high pressure chamber and the low pressure chamber in the fuel injection device. Is provided in a fuel passage communicating with the fuel passage, and the seat surface closes to a valve seat portion provided in the fuel passage to shut off the fuel passage. That is, this state is the valve closed state. A shaft extends from the end of the valve body in the direction in which the valve closes, and an armature is provided at the end of the shaft protruding from the fuel passage.

On the other hand, on the side opposite to the armature shaft,
An electromagnet is provided to attract the armature and close the valve body. The armature is urged from the electromagnet side in the valve opening direction by the first urging means, and the armature is closed by the second urging means provided between the armature and the fuel passage. It is biased in the valve direction.

In the metering solenoid valve of the present invention, the armature is normally operated when the electromagnet is not excited and the pressure difference between the high pressure chamber and the low pressure chamber is small.
The seat surface of the valve element is arranged at a predetermined initial position by a balance between the urging force of the first urging means and the urging force of the second urging means, and the seat surface of the valve element is predetermined with respect to the valve seat portion of the fuel passage. It is located within close range.

When the electromagnet is excited in this state,
Since the armature is attracted to the electromagnet side from the above-mentioned initial position against the urging force of the first urging means, the seat surface of the valve body quickly comes into close contact with the valve seat portion of the fuel passage and Close the valve. On the other hand, when the excitation of the electromagnet is stopped in such a valve closed state, the armature moves in the valve opening direction by the urging force of the first urging means, and the seat surface of the valve body and the valve seat portion of the fuel passage are separated from each other. Separate. At this time, if the pressure difference between the high pressure chamber and the low pressure chamber is large, a large fluid pressure is applied to the seat surface of the valve body, so that the valve body is urged in the valve opening direction. Therefore,
In this case, the resultant force of the urging force of the first urging means and the fluid pressure applied to the seat surface of the valve body exceeds the urging force of the second urging means, so that the armature is located above the initial position. Further, by moving in the valve opening direction, the distance between the seat surface of the valve body and the valve seat portion of the fuel passage increases.

Then, when the pressure in the high-pressure chamber decreases thereafter, the armature returns to the above-mentioned initial position, so that the seat surface of the valve body is again arranged within a predetermined proximity range from the valve seat portion. Thus, according to the metering solenoid valve of the fuel injection device of the present invention, when the fuel injection device starts fuel injection, that is, when the valve is closed when the pressure difference between the high pressure chamber and the low pressure chamber is small. The high pressure chamber and the low pressure chamber can be quickly shut off to ensure the responsiveness of the fuel injection start. On the other hand, when the fuel injection device finishes the fuel injection, that is, when the pressure difference between the high pressure chamber and the low pressure chamber is large, the valve opening amount of the valve body becomes larger and the fuel in the high pressure chamber is quickly released. It is possible to escape to the low pressure chamber and end fuel injection quickly.

Further, in particular, in the metering solenoid valve of the present invention, both the first urging means and the second urging means are not provided at both ends of the valve body, but both are provided outside one of the fuel passages. Since it is provided, the shape of the fuel passage can be freely set.

Further, according to the solenoid valve for metering of the present invention, it is possible to prevent the volume of the fuel passage from being unnecessarily increased, so that the mounting space of the fuel injection device to which the solenoid valve is attached can be kept small. become able to. On the other hand, in the metering solenoid valve of the present invention, since the respective constituent members are arranged only on the one outer side as viewed from the fuel passage, the assemblability thereof is extremely good.

Further, in the metering solenoid valve of the present invention, since no constituent member is present on the side opposite to the armature of the electromagnet, a signal for exciting the electromagnet can be easily provided. You will be able to.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a configuration diagram showing a configuration when a metering solenoid valve to which the present invention is applied is used as an electromagnetic spill valve of a distribution type fuel injection pump.

As shown in FIG. 1, the distributed fuel injection pump of this embodiment is connected to a drive shaft 4 rotatably arranged in a pump casing 2 and a known coupling to the drive shaft 4. Cam plate 6 and
A roller ring 10 that supports a plurality of rollers 8 that come into contact with the cam surface formed on the outer peripheral surface of the cam plate 6, and a plunger 14 that is connected to the cam plate 6 and is slidably inserted into the cylinder 12. And are equipped with.

When the drive shaft 4 rotates, the cam surface of the cam plate 6 moves up and down the roller 8 of the roller ring 10. Therefore, the cam plate 6 periodically moves forward and backward as the drive shaft 4 rotates (see FIG. 1).
In the left-right direction), the plunger 14 moves forward or backward together with the cam plate 6.

The plunger 14 moves forward (see FIG. 1).
To the right), the pressure chamber 1 formed at its tip
The fuel in 6 is compressed and pressurized and supplied to the injection valve 22 through the distribution port 18 and the distribution flow path 20. Further, the plunger 14 introduces the fuel in the low pressure chamber 24 provided in the pump casing 2 into the pressure chamber 16 through the suction flow passage 26 and the suction groove 28 when retracted (to the left in FIG. 1). To do.

On the other hand, a pressure chamber flow passage 30 extends upward in FIG. 1 from the pressure chamber 16 pressurized by the plunger 14, and the pressure chamber flow passage 30 is mounted on the top surface of the pump casing 2. And an electromagnetic spill valve (hereinafter, simply referred to as an electromagnetic valve) 32. The pressure chamber flow passage 30 is connected to the low pressure chamber flow passage 36 via a fuel passage 34 provided in the electromagnetic valve 32.
Communicates with the low pressure chamber 24.

Further, as shown in FIG. 1, the drive shaft 4 is provided with a signal rotor 38 having a plurality of tooth profiles, and a pickup for detecting passage of the tooth profile is provided in the vicinity of the signal rotor 38. 40 are installed. In the present embodiment, the electronic control unit 42 provided outside the distribution type fuel injection pump performs cylinder discrimination and engine speed detection based on the detection signal from the pickup 40, and various sensors not shown. The accelerator opening degree, engine cooling water temperature, etc. are detected based on the detection signal from. Further, the electronic control unit 42
Based on these detection results, the optimum fuel injection timing and injection amount are determined, a control signal is output to the drive circuit 44, and the opening / closing control of the solenoid valve 32 is performed via this drive circuit 44.

Here, the internal structure of the solenoid valve 32 will be described in detail with reference to FIG. In the following explanation,
The lower side means the pump casing 2 side, and the upper side means the side opposite to the pump casing 2. As shown in FIG. 2, the solenoid valve 32 of the present embodiment is provided with the pressure chamber flow channel 30 described above.
And a low-pressure chamber flow path 36 are connected at both ends to a fuel passage 34, a tubular valve housing 52 that houses the valve body 50, and a valve body 5
A spool 54 as a valve body that is inserted into a fuel passage 34 passing through the center position of 0 and slides in the vertical direction to connect and disconnect the fuel passage 34, and a shaft of the spool 54 protruding upward from the valve body 50. A ring-shaped stopper 56 slidably inserted into the portion 54a, a plate-shaped armature 58 provided at the tip of the shaft portion 54a, and an opening of the valve housing 52 on the side opposite to the pump casing 2 are provided. A bottomed cylindrical cap housing 60 that closes, an electromagnet 62 that is provided on the bottom surface of the cap housing 60, that is, an upper part of the valve housing 52, and that attracts the armature 58 at the time of excitation, and is installed in the valve housing 52, and also the cap housing. The ring member 64 inserted between the open end of the valve body 60 and the valve body 50, and the armature 58 from the electromagnet 62 side. Biases, the first spring 66 as first urging means, the armature 58 and the stopper 5
6 and a second spring 68 as a second urging means.

Here, as shown in FIG. 2, the valve housing 52 is screwed to the pump casing 2 by a screw 52a formed on the outer periphery thereof. On the other hand, the electromagnet 62 is formed by winding the coil 72 around the magnetic core 70, inserting the coil 72 into the cap housing 60, and injecting the resin 74 into the outer periphery thereof. Further, the opening of the valve housing 52 is sealed by an O-ring 76 provided on the outer periphery of the cap housing 60 near the lower portion.

The spool 54 has a shaft portion 5 provided with an armature 58 from the lower end portion 54b in the fuel passage 34.
The second stage 54 has three kinds of outer diameters that gradually decrease toward 4a, and the outer diameter decreases by one stage from the lower end portion 54b.
A tapered seat surface 80 that is in close contact with a valve seat portion 78 that is circumferentially provided in the fuel passage 34 is formed at a portion up to c. The outer shape of the second step 54c is set to be larger than the inner diameter of the stopper 56 inserted in the shaft portion 54a.

The urging force of the second spring 68 is set to be larger than the urging force of the first spring 66. In addition, the space in which the armature 58 is provided and the spool 54
The lower portion 82 has the same pressure as that of the low pressure chamber 24 due to a communication passage (not shown). Next, the solenoid valve 3 configured in this way
The operation No. 2 will be described with reference to FIG. Note that FIG. 3 schematically shows the operation of the solenoid valve 32.

First, when the electromagnet 62 is in a non-excited state and the pressures in the pressure chamber 16 and the pressure chamber passage 30 are substantially the same as the pressures in the low pressure chamber passage 36 and the low pressure chamber 24,
The initial state shown in FIGS. 2 and 3A is obtained. That is, in this initial state, the armature 58 is
The spring 66 urges the valve body 50 side, and the second spring 68 urges the stopper 56 to the electromagnet 62 side while the stopper 56 is in contact with the valve body 50. Here, as described above, the urging force of the second spring 68 is larger than the urging force of the first spring 66, and the outer diameter of the second step 54c of the spool 54 is the stopper 56.
Since it is larger than the inner diameter of the spool 54, the spool 54 stops when the step between the second step 54c and the shaft 54a is located at the upper end surface of the valve body 50. And at this time,
The distance between the valve seat 78 in the fuel passage 34 and the seat surface 80 of the spool 54 is L1 as shown in FIG. 3 (A).

Then, when the lift of the plunger 14 (movement to the right in FIG. 1) is started in the distribution type fuel injection pump and a predetermined time elapses, the electronic control unit 42 outputs a control signal to the drive circuit 44. The drive circuit 44 energizes the coil 72 of the electromagnet 62 (the "ON" point in FIG. 3).

Then, the armature 58 is attracted to the side of the electromagnet 62 by the electromagnetic attraction force of the electromagnet 62.
As shown in (B), the spool 54 has its seat surface 8
0 stops at a position close to the valve seat portion 78 in the fuel passage 34. That is, the separation distance between the valve seat portion 78 and the seat surface 80 becomes zero.

As a result, the fuel passage 34 is cut off, so that the pressure chamber flow passage 30 and the low pressure chamber flow passage 36 are cut off, and thereafter the fuel in the pressure chamber 15 is removed as the plunger 14 is lifted. It is compressed and pressurized, and fuel injection is started from the injection valve 22 through the distribution flow path 20.

After that, when the fuel injection amount reaches a predetermined value,
The drive circuit 44 stops energizing the electromagnet 62 in response to a command from the electronic control unit 42 (“OFF” in FIG. 3).
Point). Then, the spool 54 moves to the valve body 50 side, that is, in the valve opening direction by the urging force of the first spring 66. At this time, the spool 54 is further urged in the valve opening direction. That is, at this time, the fuel passage 3
The high pressure fuel from the pressure chamber 16 flows between the valve seat portion 78 of No. 4 and the seat surface 80 of the spool 54, so that the fluid pressure urges the spool 54 in the valve opening direction. .

The resultant force of the urging force of the fluid pressure and the urging force of the first spring 66 is the second spring 68.
3C, the spool 54 descends to a position where the step between the second step 54c and the shaft 54a is lower than the upper end surface of the valve body 50, as shown in FIG. 3C. To do. Therefore, at this time, the separation distance between the valve seat portion 78 in the fuel passage 34 and the seat surface 80 of the spool 54 becomes L2, which is larger than L1, as shown in FIG. 3C.

As a result, the fuel passage 34 opens greatly and the fuel pressure in the pressure chamber 16 drops sharply.
The fuel injection from the engine stops immediately. Then, when the pressure in the pressure chamber 16 decreases and the biasing force due to the fluid pressure decreases in this way, the spool 54 moves upward due to the biasing force of the second spring 68, and returns to the initial state described above. Therefore, when the valve is closed next time, the electromagnet 62 needs to attract the spool 54 by L1.
Fast responsiveness is secured.

As described above, according to the solenoid valve 32 of this embodiment, when the distribution type fuel injection pump starts fuel injection, that is, when the lift of the plunger 14 is started and the pressure of the pressure chamber 16 is still small. The spool 54 is pushed up to the position where the seat surface 80 is close to the valve seat portion 78 by the action of the second spring 68 and the stopper 56, so that the responsiveness of the fuel injection start can be secured. it can.

On the other hand, when the distribution type fuel injection pump finishes fuel injection, that is, when the fuel injection amount reaches a predetermined value, the pressure chamber 1
When the pressure of 6 is still high, the spool 54 is pushed down to a position where the distance between the seat surface 80 and the valve seat 78 becomes larger, so that the fuel in the pressure chamber 16 quickly escapes to the low pressure chamber 24. Thus, the fuel injection can be ended quickly.

In particular, the solenoid valve 32 of the present embodiment is configured without being arranged in the fuel passage 34 except for the spool 54. Therefore, according to the solenoid valve 32 of this embodiment, the shape of the fuel passage 34 can be freely set. Further, since the volume of the fuel passage 34 can be prevented from being increased more than necessary, the mounting space in the pump casing 2 can be kept small.

In the solenoid valve 32 of this embodiment, the first spring 66, the second spring 68 and the stopper 56 are arranged only on the side of the valve body 50 opposite to the pump casing 2. The assemblability becomes extremely good. Further, in the solenoid valve 32 of this embodiment, the electromagnet 62 is provided above the armature 58, so that the electromagnet 62 from the drive circuit 44 is provided.
Wiring to is extremely easy.

In the above embodiment, the solenoid valve 32 is used for the distribution type fuel injection pump, but it may be used for a so-called unit injector in which the fuel injection pump and the injection valve are integrated. .

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a distributed fuel injection pump according to an embodiment.

FIG. 2 is a configuration diagram showing an electromagnetic spill valve attached to a distribution type fuel injection pump.

FIG. 3 is an explanatory diagram illustrating the operation of the electromagnetic spill valve.

[Explanation of symbols]

2 ... Pump casing 16 ... Pressure chamber 24 ... Low pressure chamber 30 ... Pressure chamber flow passage 32 ... Electromagnetic valve 34 ... Fuel passage 36 ... Low pressure chamber flow passage 50 ... Valve body 5
2 ... Valve housing 54 ... Spool 54a ... Shaft portion 56 ... Stopper 58 ... Armature 62 ... Electromagnet 66 ... First spring 68 ... Second spring 78 ... Valve seat portion 80 ... Seat surface

Claims (1)

[Claims] 1. A fuel passage, which connects a high pressure chamber and a low pressure chamber in a fuel injection device, and a seat surface provided in the fuel passage and formed in a tapered shape. A valve body that closes the fuel passage by closely contacting a valve seat portion provided in the passage; and a shaft portion that extends from the end portion of the valve body in a direction in which the valve body closes and that protrudes from the fuel passage. An armature provided at an end portion of the shaft portion opposite to the valve body, and an armature provided at an end portion of the armature opposite to the shaft portion, and being excited to attract the armature, the valve body An electromagnet for closing the valve, a first urging means for urging the armature from the electromagnet side in a direction in which the valve body opens, and the armature provided between the fuel passage and the armature. Second urging means for urging the magnet side, In a normal state, the seat surface of the valve body is within a predetermined proximity range to the valve seat portion of the fuel passage by the urging force of the first urging means and the urging force of the second urging means. A solenoid valve for metering a fuel injection device, characterized in that