KR20060053179A - Fuel injection valve - Google Patents

Abstract

assignment

It provides a fuel injection valve effective for stabilizing the flow rate of the fuel.

Resolution

In the fuel injection valve 10, in the valve closed state, a partition region is formed by opposing surfaces of the valve 30 and the valve seat 40 that face each other. The partition area consists of a 1st space part and a 2nd space part. The first space is formed outside the fuel injection hole 41b. The second space is formed between the inlet of the fuel injection hole 41b and the portion where the inner diameter of the fuel inlet 41b is constant in the fuel injection hole 41b. The sum total of the volumes of the 1st space part and the 2nd space part is set in the range of [0.1 [kV] <= total volume <= 0.15 [kV]].

Description

FUEL INJECTION VALVE

1 is a longitudinal sectional view of a fuel injection valve 10 which is one embodiment of a fuel injection valve of the present invention.

FIG. 2 is an enlarged view of a portion indicated by (W) of the fuel injection valve 10 in FIG. 1 in the valve open state.

3 is an enlarged view of the portion indicated by (W) of the fuel injection valve 10 in FIG. 1 in the process of shifting from the valve open state to the valve closed state.

4 is an enlarged view of a portion indicated by (W) of the fuel injection valve 10 in FIG. 1 in the valve closed state.

FIG. 5 is a cross-sectional view of the V-V line of FIG. 2.

Fig. 6 is a graph showing the relationship between the dead volume D / V [k], the flow rate ratio [%] and the flow rate deviation [%].

7 is an enlarged view of the inlet side of the fuel injection hole 41b of FIG. 4.

8 is an enlarged view showing the protruding surface 44 of another embodiment.

9 is an enlarged view showing the protruding surface 45 of another embodiment.

10 is an enlarged view showing the protruding surface 46 of another embodiment.

Explanation of symbols on the main parts of the drawings

10: fuel injection valve

20: main body

21: fixed core part

21a: fuel passage

22: support

23: sleeve

24: filter

30: valve (valve body)

31: valve body

31a: fuel passage

31b: communication hole

32: valve tip

32a: concave

32b: abutment

32c: cross section

32d: notch

33: elastomer

33a: protrusion

33b, 33c, 33d: space part

35: spring adjester

35a: fuel passage

36: spring

40: valve seat

41: valve seat body

41a: abutment

41b: fuel injection hole

41c: groove

41d: fuel passage

42: fuel introduction path

43, 44, 45, 46: projection surface

50: drive unit

51: coil

The present invention relates to a fuel injection valve which is preferred as a fuel injection valve of an internal combustion engine, especially an internal combustion engine using liquefied gas fuel.

As a fuel of an internal combustion engine, liquid fuel, such as gasoline, and liquefied gas fuel, such as liquefied petroleum gas (LPG), are used.

In an internal combustion engine using liquefied gas fuel, liquefied gas fuel is supplied to the fuel injection valve in a liquid state and injected from the fuel injection valve in a liquid state. For this reason, the fuel injection valve of the internal combustion engine which uses liquefied gas fuel requires high internal pressure compared with the fuel injection valve of the internal combustion engine which uses liquid fuel. A fuel injection valve of an internal combustion engine using liquefied gas fuel is described, for example, in Japanese Patent No. 3329945.

In the fuel injection valve described in Japanese Patent No. 3329945, when the fuel injection hole is closed by the valve body, a space portion larger in diameter than the fuel injection hole is formed between the valve body and the fuel injection hole.

When the fuel injection hole is closed by the valve body, the larger the volume of the space portion formed between the valve body and the fuel injection hole is effective to suppress the flow resistance of the fuel.

On the other hand, if the volume of this space portion is too large, when the fuel injection hole is opened, the liquid fuel expands and the pressure drops. When the pressure of the liquid fuel decreases, the liquid fuel tends to vaporize, and a gas-liquid two-phase condition tends to occur. And when the gas-liquid two-phase state arises, there exists a possibility that the supply flow volume of liquid fuel may become unstable.

This invention is made | formed in view of such a point, and an object of this invention is to provide the fuel injection valve effective for stabilizing a fuel flow rate.

(1st invention)

1st invention corresponds to the invention of Claim 1.

The present invention includes at least a valve seat and a valve. A fuel injection hole for injecting fuel is formed in the valve seat. The valve can contact the valve seat. When the valve contacts the valve seat, the inlet of the fuel injection hole is closed, and the injection of fuel through the fuel injection hole is stopped. On the other hand, when the contact between the valve and the valve seat is released, the inlet of the fuel injection hole is opened to start the injection of fuel through the fuel injection hole.

The "fuel injection valve" of the present invention can be used as a fuel injection valve for injecting various fuels including LPG, but can be suitably used as a fuel injection valve for injecting liquefied gas fuel in a liquid state.

The "valve" and "valve seat" of the present invention can stop the injection of fuel by bringing the valve and the valve seat into contact with each other, and also start the injection of fuel by release of the contact between the valve and the valve seat. If it is a configuration. As a method of making a valve and a valve seat contact, the method of making an elastic body and a contact surface contact.

In the present invention, in the valve closing state, a partition region is formed by opposing surfaces of the valve and the valve seat that face each other. This partition area consists of a 1st space part and a 2nd space part. The first space portion is formed outside the fuel injection hole. The second space portion is formed between the inlet of the fuel injection hole and the portion where the inner diameter of the fuel injection hole is constant (normal) in the fuel injection hole. This second space portion is reduced, for example, as the corner R of the inlet of the fuel injection hole becomes smaller. In addition, the flow rate of the fuel injected from the fuel injection valve is typically measured in the fuel injection hole. And in this invention, the sum of the volume of these 1st space part and the 2nd space part is set so that it may become in the range of [0.1 [kV] <= total volume <= 0.15 [kV]].

By configuring the partition area in this manner, the degree of decompression (or range) of the fuel due to the expansion of the fuel when the valve is switched from the valve closed state to the valve open state, that is, when the inlet of the fuel injection hole is opened from the closed state. Can be suppressed. Therefore, formation of the gas-liquid two-phase state of fuel can be suppressed, and the flow volume of the fuel injected from a fuel injection valve can be stabilized. It is also possible to suppress the flow rate resistance of the fuel.

(2nd invention)

2nd invention corresponds to the invention of Claim 2.

According to the first aspect of the present invention, fuel flows into the inlet of the fuel injection hole from the outer circumference by opposing surfaces of the valve and the valve seat that face each other in a direction crossing the axial direction of the fuel injection hole in the valve open state. A fuel inlet path is formed. In addition, in this invention, the diameter D of the inflow port of a fuel injection hole is set to the value which added 0.2 [mm] to the internal diameter d1 of a fuel injection hole [D <= (d1 + 0.2 [mm])]. Further, the inner circumferential surface on the inlet side of the fuel injection hole is formed as a projection surface protruding toward the axial center of the fuel injection hole.

With such a configuration, when the fuel flows into the fuel injection hole from the outer circumference through the fuel inflow passage in the valve open state, the fuel inflow passage acts as the fuel interval. As a result, the fuel is sufficiently stirred. In addition, it becomes possible to suppress the expansion of the volume of the space portion on the inlet side of the fuel injection hole.

Therefore, when switching from the valve closed state to the valve open state, it becomes possible to suppress that the gas-liquid two-phase state is formed. In addition, since a stable (homogeneous) gas-liquid two-phase state can be formed in the valve opening state, the flow rate of the fuel injected from the fuel injection valve can be stabilized more. In addition, the flow resistance of the fuel can be suppressed.

(Third invention)

3rd invention corresponds to the invention of Claim 3.

The present invention includes at least a valve seat and a valve. A fuel injection hole for injecting fuel is formed in the valve seat. The valve can contact the valve seat. Moreover, the elastic body which has an annular protrusion part is formed in one of a valve and a valve seat, and the contact surface is formed in the other. The protrusion of the elastic body can abut on the abutting surface. When the projection of the elastic body abuts on the contact surface, the inlet of the fuel injection hole is closed, and the injection of fuel through the fuel injection hole is stopped. On the other hand, when the contact between the protrusion of the elastic body and the contact surface is released, the inlet of the fuel injection hole is opened to start the injection of fuel through the fuel injection hole.

The "fuel injection valve" of the present invention can be used as a fuel injection valve for injecting various fuels, including LPG, but can be suitably used as a fuel injection valve for injecting liquefied gas fuel in a liquid state.

Moreover, in this invention, after the protrusion part of an elastic body abuts on the contact surface, it is comprised so that a valve may abut on a valve seat. In this way, the opening and closing of the inlet of the fuel injection hole is performed by the contact between the protrusion of the elastic body and the contact surface or the release of the contact, so that the sealing property is improved. And since the valve | bulb is comprised so that the valve seat may contact | abut with the valve seat after the protrusion part of an elastic body abuts on the contact surface, the deformation amount of an elastic body is restrict | limited. This prevents premature deterioration of the elastic body.

The "elastic projection" and "butting surface" of the present invention can stop the injection of fuel by the contact of the elastic projection with the contact surface, and the contact of the elastic projection with the contact surface What is necessary is just a structure which can start injection of fuel by being canceled.

The contact surface with the elastic body may be formed on either the valve or the valve seat. In addition, the shape and arrangement position of the contact surface with the elastic body can be appropriately selected. In addition, the contact structure of the valve and the valve seat can be appropriately selected.

In the present invention, the partition region is formed by the contact surface with the elastic body in the valve closing state. This partition area | region consists of a 1st space part and a 2nd space part similarly to 1st invention. And it is set so that the sum of the volumes of a 1st space part and a 2nd space part may be in the range of [0.1 [kV] <= sum of volumes ≤ 0.15 [kV]].

By configuring the partition area in this manner, the same effects as in the first invention can be obtained.

(Fourth invention)

4th invention corresponds to the invention of Claim 4.

In the third invention, in the valve opening state, the inlet of the fuel injection hole is formed from the outer circumference by the opposing surfaces of the valve, the valve seat, and the elastic body facing each other in the direction crossing the axial direction of the fuel injection hole. There is a fuel inlet path through which fuel flows. In addition, as in the second invention, the diameter D of the inlet of the fuel injection hole is set to the value obtained by adding 0.2 [mm] to the inner diameter d1 of the fuel injection hole, while [D≤ (d1 + 0.2 [mm]) ], The inner circumferential surface on the inlet side of the fuel injection hole is formed as a projection surface protruding toward the axial center of the fuel injection hole.

(5th invention)

5th invention is the fuel injection valve of Claim 5.

The present invention has at least a valve seat and a valve having the same configuration as the first invention. Further, in the present invention, the fuel inflow path in which fuel flows into the inlet of the fuel injection hole from the outer circumference by the opposing surfaces of the valve and the valve seat facing each other in the direction crossing with the axial direction of the fuel injection hole in the valve open state. Is formed. In addition, in this invention, the diameter D of the inflow port of a fuel injection hole is set to the value which added 0.2 [mm] to the internal diameter d1 of a fuel injection hole [D <= (d1 + 0.2 [mm])]. The inner circumferential surface on the inlet side of the fuel injection hole is formed as a projection surface protruding toward the axial center of the fuel injection hole.

With such a configuration, when the fuel flows into the fuel injection hole from the outer circumference through the fuel inflow passage in the valve open state, the fuel inflow passage acts as a galloping section of the fuel. As a result, the fuel is sufficiently stirred. In addition, it becomes possible to suppress the expansion of the volume of the space portion on the inlet side of the fuel injection hole.

Therefore, when switching from the valve closed state to the valve open state, it becomes possible to suppress that the gas-liquid two-phase state is formed. Further, in the valve open state, a stable (homogeneous) gas-liquid two-phase state can be formed, and the flow rate of the fuel can be more stabilized.

(6th invention)

6th invention is the fuel injection valve of Claim 6.

This invention is equipped with the valve seat, the valve | bulb, an elastic body, and the contact surface of the structure similar to 3rd invention. Further, in the present invention, the fuel injection hole is formed from the outer circumference by the opposing surfaces of the valve, the valve seat, and the elastic body that face each other in the direction crossing with the axial direction of the fuel injection hole in the valve open state. There is a fuel inlet path through which fuel enters the inlet. In addition, in this invention, the diameter D of the inflow port of a fuel injection hole is set to the value which added 0.2 [mm] to the internal diameter d1 of a fuel injection hole [D <= (d1 + 0.2 [mm])]. The inner circumferential surface on the inlet side of the fuel injection hole is formed as a projection surface protruding toward the axial center of the fuel injection hole.

In addition, when the contact surface formed in the valve or the valve seat functions as an opposing surface of the valve or the valve seat, the fuel inflow path is brought into contact with the valve and the elastic body, or the valve seat and the elastic body. It is formed by the contact surface. This invention also includes a structure in this way.

Therefore, when switching from the valve closed state to the valve open state, it becomes possible to suppress that the gas-liquid two-phase state is formed. In addition, a stable (homogeneous) gas-liquid two-phase state can be formed in the valve open state, and the flow rate of the fuel can be stabilized more.

The configuration and operation of the fuel injection valve 10 of one embodiment of the present invention will be described below with reference to the drawings.

The longitudinal cross-sectional view of the fuel injection valve 10 of this embodiment is shown in FIG. The fuel injection valve 10 of this embodiment is a fuel injection valve for injecting a liquid LPG in a liquid state supplied from a fuel tank. This fuel injection valve 10 has a main body 20, a valve (valve body 30), a valve seat 40, and a drive unit 50.

The main body 20 is formed in a cylindrical shape. The hole on the inner circumferential side of the main body 20 is used as the fuel passage 21a. The main body 20 has a fixed core portion 21 disposed on an upstream side (upper side in FIG. 1) and a support portion 22 disposed on a downstream side (lower side in FIG. 1). The fixed core part 21 and the support part 22 are formed of the magnetic material. The fixed core portion 21 and the support portion 22 are connected via a sleeve 23 formed of a nonmagnetic material.

Moreover, the filter 24 for filtering the LPG supplied to the fuel passage 21a is provided in the upstream of the fuel passage 21a.

The valve 30 has a valve body 31 and a valve tip portion 32 joined to a downstream side (lower side in FIG. 1) of the valve body 31. The valve 30 can abut the valve seat 40. This valve 30 corresponds to the "valve which can contact the valve seat" of this invention. The valve body 31 and the valve tip portion 32 are formed of different materials. Of course, you may integrally form the valve body 31 and the valve tip part 32 from the same material. Moreover, at least the valve body 31 is formed of the magnetic material among the valve body 31 and the valve tip part 32.

The valve body 31 is formed in a tubular shape having a step. The valve tip portion 32 is formed in a tubular shape having a bottom. The hole on the inner circumferential side of the valve body 31 and the valve tip portion 32 is used as the fuel passage 31a. Moreover, the communication hole 31b which communicates with the fuel passage 41a formed by the fuel passage 31a and the valve seat body 41 is formed in the side wall of the valve body 31. As shown in FIG.

The valve 30 is freely formed in the axial direction (up and down direction in FIG. 1) with respect to the support part 22 and the valve seat 40 (valve seat body 41).

The valve tip portion 32 has abutting portion 32b and an elastic body 33 on the downstream side (a side facing the abutting surface 41a of the valve seat 40) (see FIG. 2).

In addition, the detail of the valve tip part 32 and the elastic body 33 is mentioned later.

The valve seat 40 has a valve seat body 41. The valve seat body 41 is attached to the inner circumferential surface of the support part 22 by press fitting or the like. The valve seat 40 has a fuel injection hole 41b. This valve seat 40 corresponds to the "valve seat" of this invention.

The valve seat body 41 is formed in a cylindrical shape having a bottom. In the bottom part of the valve seat body 41, the contact surface (contact surface 41a in FIG. 2) and the fuel injection hole 41b are formed. The inflow port of the fuel injection hole 41b is formed in the contact surface 41a.

The hole on the inner circumferential side of the valve seat body 41 is used as the fuel passage 41d. Moreover, the groove part 41c is formed in the axial direction (up-down direction of FIG. 1) in the inner peripheral surface which opposes the valve tip part 32 of the valve seat body 41. As shown in FIG. Thereby, LPG can flow out into the fuel injection hole 41b through the groove part 41c in the fuel passage 41d.

In addition, the detail of the valve seat body 41 is mentioned later.

In this embodiment, a spring 36 for generating an elastic force to move the valve 30 in the direction toward the valve seat 40 (the direction of closing the inlet of the fuel injection hole 41b) is formed. . This spring 36 is formed between the spring adjuster 35 and the valve 30 (valve body 31).

The spring adjuster 35 is formed in a cylindrical shape. The spring adjuster 35 is fixed to a predetermined position of the inner circumferential surface of the main body 20 (fixed core portion 21) by caulking or the like. By adjusting the fixed position of the spring adjuster 35, the elastic force of the spring 36 for moving the valve 30 in the direction toward the valve seat 40 can be adjusted.

The hole on the inner circumferential side of the spring adjuster 35 is used as the fuel passage 35a. As a result, the LPG is supplied to the fuel injection hole 41b through the filter 24, the fuel passages 21a, 35a, 31a, 41d, and the groove portion 41c.

Further, when the valve 30 is in contact with the contact surface 41a of the valve seat 40, a minute gap is formed between the fixed core portion 21 and the valve 30 (valve body 31). The main body 20, the valve 30, and the valve seat 40 are disposed.

The drive part 50 which drives the valve 30 is comprised by the fixed core part 21 and the coil 51 arrange | positioned so that the fixed core part 21 may be wound.

Here, the coil 51 is coat | covered with the resin molding 61 with the majority of the main body 20. As shown in FIG. The socket portion 61a is formed in the resin molded body 61. The connector 62 which is connected to the coil 51 is formed in the socket part 61a. As a result, the coil 51 can be connected to the external power supply device via the connector 62.

Next, the structure of the principal part shown by (W) of the fuel injection valve 10 in FIG. 1 is demonstrated using FIG. 2 and FIG. Here, in FIG. 2, the part shown by (W) of the fuel injection valve 10 in FIG. 1, when the valve 30 is in an open position (position where the valve body 31 abuts the main body 20) is shown. An enlarged view is shown. 5, the cross section of the V-V line | wire in FIG. 2 is shown. And as shown in FIG. 2, the state in which the valve 30 exists in a closed position is called "valve closed state."

As described above, the valve tip portion 32 is formed in a cylindrical shape having a bottom. The recessed part 32a and the contact part 32b are formed in the contact surface 41a side of the valve seat body 41 of this valve tip part 32. As shown in FIG. The recessed part 32a is notched in a columnar shape. The contact part 32b is formed in the radial direction outer side of the valve tip part 32 rather than the recessed part 32a. The contact portion 32b is formed in an annular shape and protrudes toward the valve seat 40 side. The front end surface (end surface, 32c) of the contact part 32b of the contact surface 41a side of the valve seat body 41 acts as a contact surface. The elastic body 33 is attached to the recessed part 32a by an adhesive agent.

The elastic body 33 is formed of the rubber material. The elastic body 33 has a cylindrical base and an annular protrusion 33a protruding from the base toward the valve seat 40 side. This projection part 33a is comprised so that the space part (region 33b) may be formed in radial direction outer side, and the space part (region 33c) is formed in radial direction inner side. Moreover, as for the projection part 33a, the end surface (front end surface) of the contact surface 41a side of the valve seat body 41 contacts the valve seat body 41 rather than the front end surface 32c of the contact part 32b. It is comprised so that it may protrude to the surface 41a side. The distance between the distal end face of the protruding portion 33a and the distal end face 32c of the abutting portion 32b is set to a distance that can prevent deformation of the elastic body 33 more than necessary and prevent premature deterioration of the elastic body 33. do.

In addition, in this embodiment, when the fuel injection hole 41b is closed, the elastic body 33, the valve tip 32 (valve 30), and the valve seat body 41 (valve seat 40) are used. The discharge part which discharge | releases LPG stored in the space part (region 33b) (refer FIG. 4) to be formed is formed. This discharge portion is provided to the four notches 32d formed so as to communicate the space portion 33b and the groove portion 41c (see FIG. 1) with the front end surface 32c of the abutting portion 32b of the valve tip portion 32. It is composed by. In addition, the shape, number, arrangement | positioning position, etc. of this notch part 32d can be selected suitably according to the prescription | regulation of a product. Alternatively, by setting the surface roughness (surface roughness) of the front end surface (butt surface, 32c) of the contact portion 32b of the valve 30 to a predetermined surface roughness or higher, the front end surface 32c can be used as the discharge portion. Can be. In this case, the notch part 32d may not be necessary. And there may be no discharge part.

Next, the operation of the fuel injection valve 10 of this embodiment will be described with reference to FIGS. 1 to 4. Here, in FIG. 3, the process of moving the valve 30 from the open position to the closed position (the position where the front end surface 32c of the contact portion 32b abuts on the contact surface 41a of the valve seat body 41) is shown. The enlarged view of the part shown by (W) of the fuel injection valve 10 of is shown. 4 shows an enlarged view of the portion indicated by (W) of the fuel injection valve 10 when the valve 30 is in the closed position.

When a current is supplied to the coil 51 in FIG. 1, magnetic flux flows from the coil 51 in the directions of the fixed core portion 21, the valve body 31, the support portion 22, and the coil 51, and the valve 30. ) The force which moves the (valve body 31 and the valve front-end | tip part 32) toward the fixed core part 21 generate | occur | produces. As a result, the valve 30 overcomes the spring force of the spring 36 and moves in a direction away from the valve seat 40 (upward in FIG. 1). And the valve 30 stops in the position (open position) in which the upper end surface of the valve body 31 contact | connected the lower end surface of the fixed core part 21. As shown in FIG. That is, the valve 30 stops moving in the opening direction when the valve 30 reaches the open position.

As shown in FIG. 2, the state in which the valve 30 abuts on the fixed core part 21 and stops is called "a valve opening state."

In the valve open state, the contact between the protrusion 33a of the elastic body 33 and the contact surface 41a of the valve seat body 41 is released. As a result, the inlet port of the fuel injection hole 41b is opened.

In the valve open state, the valve front end portion 32 (valve 30) and the contact surface 41a (valve seat 40) of the elastic body 33 and the valve seat body 41 face each other. The fuel inflow path 42 is formed by the surface. This fuel inflow path 42 is along the space portion 33b and the space portion 33c in a direction (right and left direction in FIG. 2) orthogonal to the axial direction (up and down direction in FIG. 2) of the fuel injection hole 41b. It is extended. LPG flows into the fuel injection hole 41b from the outer periphery via this fuel inflow path 42. This fuel inflow path 42 corresponds to the "fuel inflow path" of this invention.

As a result, in the valve-opened state, the LPG passes from the groove portion (groove 41c in FIG. 1) through the fuel inflow path 42 and from the inlet of the fuel injection hole 41b to the interior of the fuel injection hole 41b. Inflow. And it injects from the fuel injection hole 41b, and is supplied to an internal combustion engine (engine). The flow rate of LPG at this time is measured in the fuel injection hole 41b.

In the valve open state shown in FIG. 2, when the current supply to the coil (coil 51 in FIG. 1) is stopped, the valve 30 is valve seated by the elastic force of the spring (spring 36 in FIG. 1). It moves in the direction toward 40 (down direction of FIG. 2).

And in the process of moving the valve 30 from an open position to a closed position, as shown in FIG. 3, the front end surface of the projection part 33a of the elastic body 33 will contact the contact surface 41a of the valve seat body 41. As shown in FIG. Touches. As a result, the inlet port of the fuel injection hole 41b is closed. Therefore, the inflow of LPG from the groove portion (groove 41c in FIG. 1) into the fuel injection hole 41b stops, and the injection of LPG in the fuel injection hole 41b stops.

In addition, in the state shown in FIG. 3, the valve 30 moves further toward the valve seat 40 (downward direction of FIG. 3) by the elastic force of the spring (spring 36 of FIG. 1). At this time, since the protrusion part 33a of the elastic body 33 is compressed by the contact surface 41a of the valve seat body 41, it deform | transforms. That is, the protrusion part 33a of the elastic body 33 is deformed in the direction of the space part 33b and 33c.

And as shown in FIG. 4, when the front end surface 32c of the contact part 32b of the valve front part 32 contacts the contact surface 41a of the valve seat body 41 (closed position), a valve ( 30) movement stops. That is, the valve 30 stops moving in the closing direction because the valve 30 reaches the closed position. As shown in FIG. 4, the state in which the valve 30 is in contact with the valve seat 40 is called "valve closed state."

In the "valve closed state" shown in FIG. 4, the partitioned area is formed by the elastic body 33, the protrusion 33a of the elastic body 33, the contact surface 41a of the valve seat body 41, and the fuel injection hole 41b. Is formed. The volume of this partition area, so-called "dead volume D / V", is the sum of the volumes occupied by the space portion 33c and the space portion 33d. The space portion 33c is a space portion outside the fuel injection hole 41b in the section region. The space portion 33d is the space portion 33d from the inlet of the fuel injection hole 41b to the portion (part P in FIG. 4) in which the diameter of the injection hole becomes constant (normal) in the section region. This space portion 33c corresponds to the "first space portion" of the present invention, and the space portion 33d corresponds to the "second space portion" of the present invention.

Then, when switching from the valve closed state shown in FIG. 4 to the valve open state shown in FIG. 2, and opening the inflow port of the fuel injection hole 41b, a current is supplied again to the coil 51 of FIG.

As a result, the valve 30 overcomes the elastic force of the spring 36 and moves in a direction away from the valve seat 40. That is, the front end surface 32c of the valve front end part 32 moves to the direction (upward direction of FIG. 4) away from the contact surface 41a of the valve seat body 41. As shown in FIG.

At this time, the shape of the protrusion part 33a of the elastic body 33 deformed in the valve closing state returns to the shape shown in FIG. 2 or 3 according to the movement of the valve 30. Here, when the shape of the protrusion part 33a of the elastic body 33 returns to the normal shape as shown in FIG. 2 or FIG. 3 from the deformed shape as shown in FIG. 4, the time may be delayed slightly. many. In this case, the valve 30 moves to the opening direction at the moment as it is deformed as shown in FIG. Therefore, immediately after changing from the valve closing state to the valve opening state, the volume of the region in which the LPG flows in the groove portion 41c is almost equal to the dead volume D / V in the valve closing state shown in FIG. 4. In this case, the point where the contact between the front end surface 32a of the contact portion 32b and the contact surface 41a of the valve seat body 41 is released is such that the inlet port of the fuel injection hole 41b is opened. It is time.

MEANS TO SOLVE THE PROBLEM The present inventors confirmed the following as a result of various examination about the influence by this dead volume D / V. If dead volume D / V exists, LPG expands immediately after the inlet of fuel injection hole 41b is opened, and the pressure of LPG falls. Here, when the dead volume D / V is too large, there is a fear that the LPG vaporizes and the gas-liquid two-phase state is formed by the drop in pressure due to the expansion of the LPG immediately after the inlet of the fuel injection hole 41b is opened. have. When the gas-liquid two-phase state is formed, the flow rate of the fuel injected from the fuel injection valve becomes unstable. On the other hand, in order to suppress the flow resistance of LPG, it is preferable that the dead volume D / V is larger.

(Add this part)

Therefore, the present inventors found that by setting this dead volume D / V preferably, it is possible to suppress the flow resistance while trying to stabilize the flow rate of LPG.

Here, in order to obtain the preferable setting value of the dead volume D / V formed in the valve closed state, the data of the flow rate ratio [%] with respect to the dead volume D / V [k], and the flow volume with respect to the dead volume D / V [k] Data of [%] was acquired. And using the acquired data, the graph as shown in FIG. 6 was created.

In this embodiment, the dead volume D / V can be changed by appropriately setting the inner diameter d1 or clearance d2 of the fuel injection hole 41b in FIG. The clearance d2 is a fuel injection hole 41b of the elastic body 33 in a state where the front end surface 32c of the valve tip portion 32 and the contact surface 41a of the valve seat body 41 abut. It is the distance between the point covering the inlet of and the contact surface 41a.

In this embodiment, the dead volume D / V is set from 0 to 0.5 by setting the inner diameter d1 of the fuel injection hole 41b to 0.505 [mm] and changing the clearance d2 to a range of 0 to 0.5 [mm]. The range was changed to O.35 [mm]. In addition, the data of the flow rate deviation [%] are related to two types of LPG (LPG of propane 100 [%] shown in solid line in the figure and propane 25 [%] + 75 [%] LPG in dashed line in the figure). It obtained by setting the duty ratio of the electric current supplied to the coil 51 to 10 [%], and changing the dead volume D / V.

The "flow rate ratio", "duty ratio", and "flow rate" at this time are defined as follows.

[Flow rate ratio]

In this embodiment, the "flow rate ratio" is the flow rate of the space portion occupied by the space portion 33c and the space portion 33d when the volume of the space portion occupied by the space portion 33c and the space portion 33d in FIG. When there is no resistance), the ratio of the actual flow rate to the flow rate (reference flow rate) at the reference state is shown. For example, in FIG. 6, the flow rate ratio 85 [%] indicates that the flow rate is reduced by 15 [%] with respect to the reference flow rate. This flow rate ratio can be acquired by calculation and actual measurement.

[Duty ratio]

In this embodiment, the "duty ratio" represents the ratio of the ON time to the [ON time + OFF time] of the drive pulse supplied to the coil 51 of FIG. In this embodiment, the ON time of the current is set to 2 [ms], the OFF time is set to 18 [ms], and the duty ratio is set to 10 [%].

[Flow rate variation]

In this embodiment, the "flow rate variation" is a fuel injection valve for measurement in which the variation of the flow rate when the adjustment fuel (fuel pressure 0.3 MPa (temperature 21 ° C)) in the always liquid state is suppressed within ± 2 [%]. By using, the deviation 3σ (three times the standard deviation σ) of the measured value when the flow rate was measured using the two types of LPG fuel described above is represented.

In addition, the flow volume was measured as follows. The flowmeter was provided upstream of the measurement fuel injection valve, the predetermined number of drive pulses were supplied to the measurement fuel injection valve, and the fuel injection amount per one drive pulse was calculated by measuring the fuel injection amount with a flowmeter. At this time, the frequency of the drive pulse is set to 50 [Hz] (= period 20 [ms]), and the duty ratio of the drive pulse is set to 10 [%] (ON time: 2 [ms], OFF time: 18 [ms]). It was. Moreover, the fuel pressure of LPG fuel (propane 100%) was set to 2 MPa (temperature: 50 degreeC), and the LPG fuel (25% propane 75% butane) fuel pressure was set to 0.8 MPa (temperature: 30 degreeC).

In the graph shown in FIG. 6, in order to suppress the flow resistance of LPG, it is preferable that dead volume D / V is large and flow rate ratio [%] is stable. In addition, in order to stabilize the flow volume of LPG, it is preferable to make dead volume D / V small and to suppress flow rate variation [%] low. For this reason, the lower limit of the range of the dead volume D / V for stabilizing the flow rate of the LPG while suppressing the flow resistance of the LPG is set based on the graph of the flow rate ratio [%], and the upper limit of the flow rate [%]. It is appropriate to set based on the graph.

In this embodiment, the flow volume resistance of the LPG can be suppressed, and the dead volume D / V capable of stabilizing the flow rate of the LPG, that is, the sum of the volumes of the space portion 33c and the space portion 33d of FIG. 4. Is set in the range of 0.1 to 0.15 [kV] (the "preferred range" in FIG. 6).

By configuring in this way, the flow resistance of LPG can be suppressed. In addition, the degree of decompression (or range) due to expansion immediately after the inlet of the fuel injection hole 41b is opened becomes large, and it becomes possible to suppress the formation of the gas-liquid two-phase state of LPG. Thereby, LPG measurement in a fuel injection hole can be performed in a liquid state, and the flow volume of LPG can be stabilized.

In addition, in the above, the case where time was delayed until the shape of the protrusion part 33a returned from a deformed shape to a normal shape was demonstrated. When using the elastic body with a large elastic return force, this delay is described. The time to become shorter. In this case, the contact between the front end surface 32c of the contact portion 32b and the contact surface 41a of the valve seat body 41 is released when the inlet of the fuel injection hole 41b is opened. After that, the contact between the protrusion 33a of the elastic body 33 and the contact surface 41a of the valve seat body 41 is released. For this reason, the volume of the area | region which LPG flows in in the groove part 41c immediately after switching from the valve closing state to the valve opening state is the front end surface 32c of the contact part 32b and valve seat body which are shown in FIG. Rather than the dead volume D / V when the abutting surface 41a of the 41 abuts, the protrusion 33a shown in FIG. 3 does not deform (or abuts a little deformation in contact with the abutting surface 41a). It is almost the same as dead volume D / V. Therefore, according to the elastic return characteristic of the elastic body 33, it is necessary to select suitably the area | region which calculates dead volume D / V.

In addition, in this Example, the fuel injection hole 41b shown in FIG. 4 has a shape as shown in FIG. 7 shows an enlarged view of the inlet side of the fuel injection hole 41b. As shown in FIG. 7, in this embodiment, the diameter D of the inlet port of the fuel injection hole 41b is equal to or less than the value obtained by adding 0.2 [mm] to the inner diameter d1 of the fuel injection hole 41b. It is set [D≤ (d1 + 0.2 [mm])]. Further, the inner circumferential surface on the inlet side of the fuel injection hole 41b protrudes toward the axis center of the fuel injection hole 41b in the space portion 33d (the area from the inlet to the constant diameter d1). It is formed by the projection shape surface 43 to be. In FIG. 7, the protruding surface 43 is formed as a one-corner (chamfer) having a radius of 0.1 [mm] or less, so-called corner R. In FIG. This projection shape surface 43 corresponds to the "protrusion shape surface" of this invention.

In the valve open state, LPG flows into the fuel injection hole 41b formed in the axial direction which cross | intersects the arrangement direction of a fuel inflow path through a fuel inflow path (fuel inflow path 42 of FIG. 2). By setting the radius of the corner R of the protruding surface 43 on the inlet side of the fuel injection hole 41b to 0.1 [mm] or less, the radius of the fuel inflow path is larger than the case where the radius of the corner R is larger than 0.1 [mm]. The length can be made longer. As a result, the fuel inflow path acts as the tank section of the LPG, and a sufficient fuel stirring effect is obtained. Moreover, it becomes possible to suppress that the volume of the space part 33d on the inlet side of the fuel injection hole 41b becomes larger than the case where the radius of the corner R of the projection surface 43 is larger than 0.1 [mm]. Thereby, it becomes possible to suppress formation of the gas-liquid two-phase state of LPG. Moreover, even when the gas-liquid two-phase state of LPG is formed, a stable (homogeneous) gas-liquid two-phase state is formed. Therefore, the metering of LPG in the fuel injection hole 41b is stable, and it becomes possible to further stabilize the flow rate.

In the above embodiment, the corner R (one corner) having a radius of 0.1 [mm] or less is formed on the inlet side of the fuel injection hole 41b, so that the volume of the space section on the inlet port side is secured. Although the reduction was made, the same effect can be obtained also by using projection surface other than the corner R. Here, with reference to FIGS. 8-10, the projection shape surface (corresponding to the "protrusion shape surface" of this invention) is demonstrated.

The projection surface 44 shown in FIG. 8 has the same circle corner as the projection surface 43 represented by the dashed-dotted line in the figure in the space portion 33d (the area until the inner diameter d1 becomes constant). Rather, it is formed as an elliptical corner. In addition, the projection surface 45 shown in FIG. 9 has two inclination surfaces (the inclination angle of the inclination surface of the first stage) in the space portion 33d (the area until the inner diameter d1 becomes constant). θa) and the inclination angle θb of the inclined surface of the second stage. In addition, the number of steps of the inclined surface which forms a projection shape may be three or more steps. Moreover, the projection surface 46 shown in FIG. 10 is formed as one end inclined surface (inclined angle (theta) c) over the space part 33d and its downstream area | region. All of these protruding surfaces 44 to 46 are formed by protruding the inner circumferential surface on the inlet side toward the axial center, similarly to the protruding surface 43.

The inner circumferential surface on the inlet side of the fuel injection hole may have a projection surface projecting toward the axial center of the fuel injection hole, and include various projection shapes including the projection surfaces 43 to 46 of the above embodiment. A configuration having a face can be used.

In addition, in this embodiment, as shown in FIG. 4, when the front end surface 32c of the contact part 32b contacts the contact surface 41a of the valve seat body 41, the elastic body 33 is carried out. LPG in a liquid state is stored in the space portion (region 33b) formed by the valve tip portion 32 (valve 30) and the valve seat body 41 (valve seat 40). LPG in the liquid state stored in this space part 33b vaporizes when heated by the heat which generate | occur | produces from an internal combustion engine. When LPG in the liquid state stored in the space part 33b vaporizes, there exists a possibility that the pressure in the space part 33b may raise and the sealing effect by the elastic body 33 will fall.

Therefore, in this embodiment, the notch part 32d which communicates the space part 33b and the groove part 41c is formed in the front end surface 32c of the contact part 32b. For this reason, when the valve 30 (valve tip part 32) contacts the valve seat 40 (valve seat body 41), LPG stored in the space part 33b is moved toward the groove part 41c. Can be released.

Therefore, when the fuel injection hole 41b is closed, the fall of the sealing effect of the elastic body 33 by the pressure rise in the space part 33b can be prevented, and the outflow of LPG to the fuel injection hole 41b is prevented. can do.

The present invention is not limited to the configuration described in the above embodiments, but various modifications, additions, and deletions are possible depending on the type of fuel, the regulation of the fuel injection valve, and the like.

In the above embodiment, the first configuration requirement for setting the volume of the dead volume D / V immediately before the fuel injection hole 41b is opened in the range of 0.1 to 0.15 [mm], and the inlet of the fuel injection hole 41b. The diameter D is equal to or less than the value obtained by adding 0.2 [mm] to the inner diameter d1 of the fuel injection hole 41b, and the inner circumferential surface of the inlet side of the fuel injection hole 41b is the axis center of the fuel injection hole 41b. Although the fuel injection valve 10 provided with the 2nd structural requirements formed in the processus | protrusion surface which protrudes toward the surface was demonstrated, what is necessary is just to provide at least one of the 1st structural requirements and the 2nd structural requirements in order to stabilize flow volume. .

In addition, although the elastic body 33 was formed in the valve 30 in the said Example, an elastic body can also be formed in the valve seat 40. FIG. In addition, although the case where the rubber material is used as the elastic body 33 has been described, as long as the fuel injection hole can be closed by contacting the elastic body with the valve seat or the elastic body with the valve, elastic bodies of various materials or structures can be used. Can be. For example, an elastic body formed of a resin material may be used. In addition, an annular elastic body may be used. Or you may use the elastic body of the shape (for example, spherical shape) which can contact the upstream edge part of a fuel injection hole.

In addition, as a valve and a valve seat in this invention, it is not limited to the valve 30 and the valve seat 40 of the structure demonstrated by the Example, The valve and valve seat of various structures can be used. For example, although the valve seat which has the contact surface which abuts an elastic body and a valve was used, the valve seat which has the contact surface which abuts an elastic body and the contact surface which a valve contacts can be used. It is also possible to lose the elastic body.

Further, in the above embodiment, a fuel injection valve for injecting liquefied petroleum gas (LPG) in the liquid state has been described, but the technique described in the present specification is for injecting liquefied gas fuel such as liquefied natural gas (LNG) into the liquid state. It is applicable when constructing a fuel injection valve and further, a fuel injection valve for injecting various fuels other than liquefied gas fuel.

By using the fuel injection valve of the 1st-6th invention, the flow volume of the fuel injected from a fuel injection valve can be stabilized.

Claims (6)

A valve seat having a fuel injection hole, and a valve capable of contacting the valve seat, and a valve in which the inlet of the fuel injection hole is closed in a valve closed state where the valve and the valve seat contact each other, and the contact between the valve and the valve seat is released. A fuel injection valve in which an inlet of a fuel injection hole is opened in an open state, and a partition region is formed by opposing surfaces of the valve and the valve seat facing each other in a valve closed state, The partition region is composed of a first space portion formed outside the fuel injection hole, and a second space portion formed between the inlet of the fuel injection hole and the portion where the inner diameter of the fuel injection hole is constant within the fuel injection hole, The sum total of the volume of a 1st space part and a 2nd space part is set to the range of [0.1 [kV] <= volume of a sum <0.15 [kV]], The fuel injection valve characterized by the above-mentioned. The method of claim 1, In the valve open state, a fuel inflow path in which fuel flows from the outer circumference to the inlet of the fuel injection hole is formed by the opposing opposing surfaces of the valve and the valve seat in a direction crossing with the axial direction of the fuel injection hole. , The diameter of the inlet of the fuel injection hole is set to be equal to or less than 0.2 [mm] plus the inner diameter of the fuel injection hole, and the inner circumferential surface of the inlet side of the fuel injection hole protrudes toward the axis center of the fuel injection hole. A fuel injection valve, characterized in that formed in the plane. A valve seat having a fuel injection hole, a valve capable of contacting the valve seat, an elastic body formed on one side of the valve and the valve seat, an elastic body having an annular protrusion, and formed on the other side of the valve and the valve seat, and a protrusion of the elastic body. The valve is configured to contact the valve seat after the protrusion of the elastic body abuts against the abutting face, and the inlet of the fuel injection hole is closed in a valve closed state where the abutment face of the elastic body abuts. A fuel injection valve which is closed and the inlet of the fuel injection hole is opened in the valve-open state in which the contact with the protrusion of the elastic body and the abutment surface is released, and the partition region is formed by the contact surface with the elastic body in the valve closed state. The partition area is composed of a first space portion formed outside the fuel injection hole, a second space portion formed between the inlet of the fuel injection hole in the fuel injection hole and a portion where the inner diameter of the fuel injection hole is constant, A fuel injection valve, characterized in that the sum of the volumes of the first space portion and the second space portion is set in a range of [0.1 [mm] ≤ volume of the sum ≤ 0.15 [mm]]. The method of claim 3, wherein In the valve open state, a fuel inflow path is formed in which fuel flows from the outer circumference to the inlet of the fuel injection hole by the opposing opposing surfaces of the valve, the valve seat, and the elastic body in the direction crossing with the axial direction of the fuel injection hole. Become, The diameter of the inlet of the fuel injection hole is set to be equal to or less than 0.2 [mm] plus the inner diameter of the fuel injection hole, and the inner circumferential surface of the inlet side of the fuel injection hole protrudes toward the axis center of the fuel injection hole. A fuel injection valve, characterized in that formed in the plane. A valve seat having a fuel injection hole and a valve capable of contacting the valve seat, the inlet of the fuel injection hole is closed in a valve closed state where the valve and the valve seat contact, and the contact between the valve and the valve seat is released. In the valve open state, the inlet of the fuel injection hole is opened, and in the valve open state, the fuel injection hole is opened from the outer circumference by the opposing surfaces of the valve and the valve seat facing each other in the direction crossing with the axial direction of the fuel injection hole. A fuel injection valve is formed to form a fuel inlet for the fuel flowing into the inlet, The diameter of the inlet of the fuel injection hole is set to be equal to or less than 0.2 [mm] plus the inner diameter of the fuel injection hole, and the inner circumferential surface of the inlet side of the fuel injection hole protrudes toward the axis center of the fuel injection hole. A fuel injection valve, characterized in that formed in the plane. A valve seat having a fuel injection hole, a valve capable of coming into contact with the valve seat, an elastic body formed on one side of the valve and the valve seat, having an annular protrusion, and formed on the other side of the valve and the valve seat, and a protrusion of the elastic body. And a contact surface capable of contacting the valve, and the valve is configured to contact the valve seat after the protrusion of the elastic body contacts the contact surface, and the inlet port of the fuel injection hole in the valve closed state where the contact surface of the elastic body contacts the contact surface. Is closed, the inlet of the fuel injection hole is opened in the valve-opening state in which the abutment of the elastic body and the abutment surface are released, and the valve and the valve in a direction crossing the axial direction of the fuel injection hole in the valve-opening state. Fuel is injected from the outer circumference to the inlet of the fuel injection hole by the opposing opposing surfaces of the seat and the contact surface with the elastic body. A fuel injection valve in which an inflow path for inflow is formed, The diameter of the inlet of the fuel injection hole is set to be equal to or less than 0.2 [mm] plus the inner diameter of the fuel injection hole, and the inner circumferential surface of the inlet side of the fuel injection hole protrudes toward the axis center of the fuel injection hole. A fuel injection valve, characterized in that formed in the plane.

Images