JP2006057564A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve effective for stabilizing the flow rate of fuel. <P>SOLUTION: In the fuel injection valve 10, a partition region is partitioned with the mutually opposed faces of a valve 30 and a valve seat 40 during closing the valve and consists of a first space portion to be formed outside a fuel injection hole 41b and a second space portion to be formed inside the fuel injection hole 41b in a range from its flow-in port to its portion having a constant inner diameter. The capacity shared by the first an second space portions is 0.1-0.15 mm<SP>3</SP>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection valve suitable as a fuel injection valve for an internal combustion engine, particularly an internal combustion engine using liquefied gas fuel.

As the fuel for the internal combustion engine, liquid fuel such as gasoline or liquefied gas fuel such as liquefied petroleum gas (LPG) is used.
In an internal combustion engine using liquefied gas fuel, the liquefied gas fuel is supplied to the fuel injection valve in a liquid state and is injected from the fuel injection valve in a liquid state. For this reason, the fuel injection valve of the internal combustion engine using liquefied gas fuel is required to have a higher pressure resistance than the fuel injection valve of the internal combustion engine using liquid fuel. As a fuel injection valve of an internal combustion engine using liquefied gas fuel, for example, a fuel injection valve described in Patent Document 1 is known.
In the fuel injection valve described in Patent Document 1, when the fuel injection hole is closed by the valve body, there is a space portion whose diameter is larger than that of the fuel injection hole between the valve body and the fuel injection hole. It has the structure formed.
Japanese Patent No. 3329945

From the viewpoint of suppressing the flow resistance of the fuel, it is effective to enlarge the volume of the space formed between the valve body and the fuel injection hole, but if the volume of the space is too large There is a concern that the gas-liquid two-phase state is likely to be formed by the expansion and decompression of the fuel when the valve is opened, thereby making the fuel flow rate unstable. Therefore, in this type of fuel injection valve, there is a demand for constructing a technique for stabilizing the flow rate of fuel by suitably designing the space formed between the valve body and the fuel injection hole and its peripheral portion. high.
This invention is made | formed in view of this point, and makes it a subject to provide a fuel injection valve effective in aiming at stabilization of the flow volume of a fuel.

(First invention of the present invention)
A first aspect of the present invention that solves the above problem is the fuel injection valve according to claim 1.
The fuel injection valve according to claim 1 includes at least a valve seat and a valve. The valve seat has a fuel injection hole for injecting fuel. The valve has a configuration capable of contacting the valve seat. When the valve is in contact with the valve seat and the valve is closed, the inlet of the fuel injection hole is closed, and fuel injection through the fuel injection hole is stopped. On the other hand, when the valve is released from contact with the valve seat, the inlet of the fuel injection hole is opened, and fuel injection through the fuel injection hole is started. The “fuel injection valve” of the present invention can be used as a fuel injection valve that injects various fuels including LPG, but the present invention is preferably used for a fuel injection valve that injects liquid gas fuel in a liquid state. Can do. In addition, as the “valve” of the present invention, valves having various structures may be used as long as the fuel injection can be stopped or started by contact or release of the valve with respect to the valve seat. Can do.
In the present invention, when the valve is closed, a partition region is formed that is partitioned by the opposing surfaces of the valve and the valve seat. This partition area consists of a first space part and a second space part. The first space portion is configured as a space formed outside the fuel injection hole in the partition region. A 2nd space part is comprised as a space formed from the inflow port in a division area to the site | part from which an internal diameter becomes constant (steady) in a fuel injection hole. For example, the second space portion is reduced as the corner R of the inlet of the fuel injection hole becomes smaller. The flow rate of fuel injected from the fuel injection valve and supplied to the internal combustion engine is typically measured in the fuel injection hole. In the present invention, the volume occupied by the first space portion and the second space portion (the sum of the volume of the first space portion and the volume of the second space portion) is 0.1 to 0.15 [mm ³ ]. It is comprised so that it may become. With the partition region having such a configuration, when the valve is switched from the valve closed state to the valve open state, the degree of decompression (or the degree) is increased, so that the gas-liquid two-phase state of the fuel is formed. It becomes possible to suppress.

(Second invention of the present invention)
A second invention of the present invention that solves the above problem is the fuel injection valve according to claim 2.
According to a second aspect of the present invention, in the fuel injection valve according to the first aspect, the fuel introduction path formed by the mutually facing surfaces of the valve and the valve seat when the valve is opened has an axial direction of the fuel injection hole. It is formed in a longitudinal shape in the intersecting direction, and the fuel that has flowed through the fuel introduction path flows from the outside of the fuel injection hole into the fuel injection hole. As an example, the fuel introduction path is formed in a longitudinal shape in a direction orthogonal to the axial direction of the fuel injection hole. In the present invention, the fuel injection hole has an inlet diameter equal to or less than a value obtained by adding 0.2 [mm] to the inner diameter of the fuel injection hole, and an inner peripheral surface on the inlet side of the fuel injection hole. It is formed on a protruding surface that protrudes toward the center of the shaft.
According to such a configuration, when the fuel that has passed through the fuel introduction path flows into the fuel injection hole formed in the axial direction intersecting the extending direction of the fuel introduction path in the valve open state, The introduction path can be used as a sufficient run-up section for fuel agitation. Moreover, according to this structure, it becomes possible to suppress that space volume is expanded in the inflow port of a fuel injection hole. Therefore, it is possible to suppress the formation of a gas-liquid two-phase state of the fuel when the valve is switched from the valve closed state to the valve open state, and it is stable (homogenized) in the valve open state. A ratio of gas-liquid two-phase states can be formed.

(Third invention of the present invention)
A third invention of the present invention that solves the above problem is the fuel injection valve according to claim 3.
The fuel injection valve according to claim 3 includes at least a valve seat and a valve having the same configuration as the valve seat and valve according to claim 1. Further, in the present invention, the fuel introduction path formed by the mutually facing surfaces of the valve and the valve seat when the valve is opened is formed in a longitudinal shape in a direction intersecting the axial direction of the fuel injection hole. The flowing fuel flows from the outside of the fuel injection hole into the fuel injection hole. As an example, the fuel introduction path is formed in a longitudinal shape in a direction orthogonal to the axial direction of the fuel injection hole. In the present invention, the fuel injection hole has an inlet diameter equal to or less than a value obtained by adding 0.2 [mm] to the inner diameter of the fuel injection hole, and an inner peripheral surface on the inlet side of the fuel injection hole. It is formed on a protruding surface that protrudes toward the center of the shaft.
According to such a configuration, in the valve open state, when the fuel flows through the first space portion into the fuel injection hole formed in the axial direction intersecting the extending direction of the first space portion, This first space can be used as a running section for fuel agitation. Moreover, according to this structure, it becomes possible to suppress that space volume is expanded in the inflow port of a fuel injection hole. Accordingly, it is possible to form a gas-liquid two-phase state with a stable (homogenized) ratio of the fuel in the valve open state.

When the fuel injection valve according to claim 1 is used, when the valve is switched from the valve closed state to the valve open state, the degree of decompression (or the degree) increases to form a gas-liquid two-phase state of the fuel. By suppressing this, the fuel can be accurately measured in the liquid phase as much as possible, and the flow rate of the fuel can be stabilized.
Further, if the fuel injection valve according to claim 2 is used, the fuel in the fuel injection hole can be measured by forming a gas-liquid two-phase state of a stable (homogenized) ratio of the fuel in the valve open state. Thus, the flow rate can be further stabilized.
Further, if the fuel injection valve according to claim 3 is used, it is possible to stabilize the flow rate by forming a gas-liquid two-phase state with a stable (homogenized) ratio of the fuel in the valve open state. Is done.

Hereinafter, the configuration and operation of the fuel injection valve 10 according to an embodiment of the “fuel injection valve” of the present invention will be described with reference to the drawings.
A longitudinal sectional view of the fuel injection valve 10 of the present embodiment is shown in FIG. The fuel injection valve 10 of the present embodiment is a fuel injection valve having a function of injecting LPG in a liquid state supplied from a fuel tank. The fuel injection valve 10 is roughly divided into a main body 20, a valve (valve element) 30, a valve seat 40, and a drive unit 50.
The main body 20 is a cylindrical member. The hole on the inner peripheral side of the main body 20 is used as a fuel passage 21a. The main body 20 has a fixed core portion 21 disposed on the upstream side (upper side in FIG. 1) and a support portion 22 disposed on the downstream side (lower side in FIG. 1). The fixed core portion 21 and the support portion 22 are formed of a magnetic material. The fixed core portion 21 and the support portion 22 are connected via a sleeve 23 made of a nonmagnetic material.
A filter 24 for filtering the LPG supplied to the fuel passage 21a is attached upstream of the fuel passage 21a.

The valve 30 has a valve body 31 and a valve tip 32 joined to the downstream side of the valve body 31 (the lower side in FIG. 1). The valve 30 corresponds to the “valve” in the present invention having a configuration capable of contacting the valve seat 40. 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 | bulb front-end | tip part 32 with the same material. Of the valve body 31 and the valve tip 32, at least the valve body 31 is made of a magnetic material.
The valve body 31 is a stepped cylindrical member, and the valve tip 32 is a cylindrical member having a bottom. The holes on the inner peripheral side of the valve body 31 and the valve tip 32 are used as the fuel passage 31a. In addition, a communication hole 31 b that communicates the fuel passage 31 a and the fuel passage 41 d formed by the valve seat body 41 is formed on the side wall of the valve body 31.
The valve 30 is disposed so as to be slidable in the axial direction (vertical direction in FIG. 1) with respect to the support portion 22 and the valve seat body 41.
The valve tip 32 has a contact part 32b (see FIG. 2) and an elastic body 33 on the downstream side (side facing the valve seat 40).
Details of the valve tip 32 and the elastic body 33 will be described later.

The valve seat 40 has a valve seat body 41. The valve seat body 41 is attached to the inner peripheral surface of the support portion 22 by press fitting or the like. The valve seat 40 corresponds to the “valve seat” in the present invention having the fuel injection hole 41b.
The valve seat body 41 is a cylindrical member having a bottom. A contact surface (contact surface 41a in FIG. 2) and a fuel injection hole 41b are formed at the bottom of the valve seat body 41.
The hole on the inner peripheral side of the valve seat body 41 is used as a fuel passage 41d. Further, a groove 41c is formed in the axial direction (vertical direction in FIG. 1) on the inner peripheral surface of the valve seat body 41 facing the valve tip 32. Thereby, LPG can flow out from the fuel passage 41d to the fuel injection hole 41b through the groove 41c.
Details of the valve seat body 41 will be described later.

In the present embodiment, a spring 36 that elastically biases the valve 30 in a direction toward the valve seat 40 (a direction in which the fuel injection hole 41b is closed) is provided. The spring 36 is provided between the spring adjuster 35 and the valve 30 (valve body 31).
The spring adjuster 35 is a cylindrical member, and is fixed to a predetermined position on the inner peripheral surface of the main body 20 (fixed core portion 21) by caulking or the like. By adjusting the fixing position of the spring adjuster 35 with respect to the main body 20 side, the biasing force of the spring 36 that elastically biases the valve 30 in the direction toward the valve seat 40 can be adjusted.
The hole on the inner peripheral side of the spring adjuster 35 is used as a fuel passage 35a. Thereby, LPG can be supplied to the fuel injection hole 41b through the filter 24, the fuel passages 21a, 35a, 31a, 41d and the groove 41c.
In the state where the valve 30 is in contact with the valve seat 40, a minute gap is formed between the fixed core portion 21 and the valve 30 (valve body 31).

The drive unit 50 that drives the valve 30 includes a fixed core portion 21 and a coil 51 that is disposed so as to surround the fixed core portion 21.
Here, the coil 51 is covered with the resin molded body 61 together with the majority of the main body 20. A socket 61a is formed in the resin molded body 61. The socket part 61 a is provided with a connector 62 connected to the coil 51. Thereby, the coil 51 can be connected to the power supply device via the connector 62.

  Next, the structure of the main part indicated by W of the fuel injection valve 10 in FIG. 1 will be described with reference to FIGS. 2 is an enlarged view of a portion indicated by W of the fuel injection valve 10 in FIG. 1, and shows a case where the valve 30 is in an open state, and FIG. 5 shows V V in FIG. The cross-sectional structure at the -V line is shown.

  As described above, the valve tip portion 32 is a cylindrical member having a bottom. A concave portion 32a and a contact portion 32b are provided on the valve seat 40 side of the valve tip portion 32. The contact portion 32b is provided on the radially outer side of the valve tip portion 32 with respect to the recess portion 32a. The contact part 32b is formed in an annular shape and protrudes toward the valve seat 40 side. A tip surface (end surface) 32c of the contact portion 32b on the valve seat 40 side functions as a contact surface. An elastic body 33 is attached to the recess 32a by adhesion or the like.

  The elastic body 33 is an elastic body formed of a rubber material, and the elastic body 33 is formed with an annular protrusion 33a that protrudes toward the valve seat 40 side. The protrusion 33a is configured such that a space portion (region) 33b is formed on the radially outer side and a space portion (region) 33c is formed on the radially inner side. Further, the end surface (front end surface) of the protrusion 33a on the valve seat 40 side is configured to protrude to the valve seat 40 side from the front end surface 32c of the contact portion 32b. The distance between the front end surface of the protrusion 33a and the front end surface 32c of the contact portion 32b is set to a distance that can prevent the elastic body 33 from being deformed more than necessary and prevent early deterioration of the elastic body 33.

  Further, in the present embodiment, when the fuel injection hole 41b is closed, a space (region) 33b formed by the elastic body 33, the valve tip 32 (valve 30), and the valve seat body 41 (valve seat 40). (See FIG. 4) An escape portion is provided to escape the stored LPG. This relief portion is constituted by four cutout portions 32d formed to communicate with the space portion 33b and the groove portion 41c (see FIG. 1) on the tip surface 32c of the contact portion 32b of the valve tip portion 32. . It should be noted that the shape, number, arrangement position, etc. of the notch 32d can be appropriately selected depending on the product specifications. Further, the surface roughness (surface roughness) of the tip surface (contact surface) 32c of the contact portion 32b of the valve 30 is formed to be equal to or greater than a predetermined surface roughness, and the tip surface 32c is used as a relief portion. it can. In this case, the notch 32d may not be provided.

  Next, operation | movement of the fuel injection valve 10 of this Embodiment is demonstrated, referring FIGS. 1-4. Here, regarding the configuration of the portion indicated by W of the fuel injection valve 10, FIG. 3 shows a case where the valve 30 is in the valve closing operation process, and FIG. 4 shows a case where the valve 30 is in the valve closed state. Indicated.

  When a current is supplied to the coil 51 in FIG. 1, magnetic flux flows from the coil 51 in the direction of the fixed core portion 21, the valve body 31, the support portion 22, and the coil 51, and the valve 30 (the valve body 31 and the valve tip portion 32). ) Is generated in a direction toward the fixed core portion 21. As a result, the valve 30 moves in a direction away from the valve seat 40 (upward in FIG. 1) against the elastic biasing force of the spring 36. Then, the valve 30 stops at a position where the upper surface of the valve body 31 is in contact with the lower surface of the fixed core portion 21.

  In this case, as shown in FIG. 2, a “valve open state” in which the valve 30 is separated from the valve seat 40 is formed. In this valve open state, the contact between the protrusion 33a of the elastic body 33 and the contact surface 41a of the valve seat 40 is released, thereby opening the inlet of the fuel injection hole 41b. Further, in this valve open state, a fuel introduction path 42 is formed on the opposed surface of the valve tip 32 and the elastic body 33 and the valve seat 40. The fuel introduction path 42 is elongated in a direction (left-right direction in FIG. 2) perpendicular to the axial direction (vertical direction in FIG. 2) of the fuel injection hole 41b along the space 33b and the space 33c. Extend. The fuel introduction path 42 corresponds to the “fuel introduction path” in the present invention. As a result, LPG flows from the groove portion (groove portion 41c in FIG. 1) through the fuel introduction path 42 from the outside of the fuel injection hole 41b into the fuel injection hole 41b, and LPG is injected through the fuel injection hole 41b. It will be supplied to the engine. The LPG flow rate at this time is measured in the fuel injection hole 41b.

When the current supply to the coil (coil 51 in FIG. 1) is stopped in the valve open state shown in FIG. 2, the valve 30 moves toward the valve seat 40 by the elastic biasing force of the spring (spring 36 in FIG. 1). Move in the direction (downward in FIG. 2).
As shown in FIG. 3, in the process of closing the valve 30, the tip surface of the protrusion 33 a of the elastic body 33 comes into contact with the contact surface 41 a of the valve seat body 41, thereby closing the fuel injection hole 41 b. The As a result, the inflow of LPG from the groove (groove 41c in FIG. 1) to the fuel injection hole 41b is stopped, and the injection of LPG from the fuel injection hole 41b is stopped.

In the state shown in FIG. 3, when the valve 30 moves further in the direction toward the valve seat 40 (downward in FIG. 3) by the elastic biasing force of the spring (spring 36 in FIG. 1), the elastic body 33 The protrusion 33a is compressed and deformed by the contact surface 41a of the valve seat body 41. That is, the protrusion 33a of the elastic body 33 is deformed toward the space portions 33b and 33c.
As shown in FIG. 4, when the tip surface 32c of the contact portion 32b of the valve tip portion 32 contacts the contact surface 41a of the valve seat body 41, the downward movement of the valve 30 in the drawing is stopped. To do. Thereby, in a state where the valve 30 is in contact with the valve seat 40, a “valve closed state” in which the movement is completely stopped is formed.

  In this “valve closed state” shown in FIG. 4, a partition region defined by 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 space 33c and the space from the inlet of the fuel injection hole 41b to the part where the injection hole diameter is constant (steady) (part P in FIG. 4). It is defined as the volume occupied by the portion 33d. The space portion 33c corresponds to the “first space portion” in the present invention, and the space portion 33d corresponds to the “second space portion” in the present invention.

  Thereafter, when switching from the valve closed state shown in FIG. 4 to the valve open state shown in FIG. 2, the current is supplied again to the coil 51 in FIG. 1. As a result, the distal end surface 32c of the valve distal end portion 32 moves in a direction away from the contact surface 41a of the valve seat 40 (upward in FIG. 4) against the elastic biasing force of the spring 36. In this embodiment, at this time, the protrusion 33a of the elastic body 33 once deformed in the valve closed state has a slight time delay until it returns to the shape as shown in FIG. 2 or FIG. Moves upward in the deformed state shown in FIG. Therefore, immediately after switching from the valve closed state to the valve open state, the volume of the region where LPG flows into the fuel injection hole 41b substantially matches the dead volume D / V in the valve closed state shown in FIG. It becomes.

  As a result of intensive studies on the dead volume D / V, the present inventors have found that if the dead volume D / V is too large, immediately after the valve closed state is switched to the valve open state, When the contact between the contact surface 41a of the valve seat body 41 and the valve seat body 41 is released, a gas-liquid two-phase state is formed by the expansion and decompression of the LPG, and the LPG flow rate may become unstable. Confirmed that it will be. The inventors have found that by appropriately setting the dead volume D / V, it is possible to suppress the flow resistance of the LPG and to stabilize the flow rate.

Here, based on FIG. 6, the suitable setting value of the dead volume D / V formed in the valve closed state will be described. In the present embodiment, in order to obtain a suitable set value of the dead volume D / V, the correlation between the dead volume D / V [mm ³ ] and the flow rate ratio [%], and the dead volume D / V [mm ³ ] Data was collected for correlation with flow rate variation [%], and a graph as shown in FIG. 6 was obtained.
In the present embodiment, the dead volume D / V can be varied by appropriately setting the inner diameter d1 of the fuel injection hole 41b and the clearance d2 in FIG. In the present embodiment, for example, the inner diameter d1 of the fuel injection hole 41b is set to 0.505 [mm], and the clearance d2 is made variable in the range of 0 to 0.5 [mm], whereby the dead volume D / V was made variable within a range of 0 to 0.35 [mm ³ ]. As for the flow rate variation [%], the data when the duty ratio is 10 [%] is used, and two types of LPG compositions (propane 100 [%] shown by a solid line in the figure and broken lines in the figure). Data for propane 25 [%] + butane 75 [%] shown) was obtained. Further, the “flow rate ratio”, “duty ratio”, and “flow rate variation” at this time are defined as follows.

[Flow ratio]
The “flow rate ratio” in the present embodiment is the reference state when the space volume occupied by the space portion 33c and the space portion 33d in FIG. 4 is infinite, that is, when there is no flow resistance in the space volume. The ratio of the actual flow rate to the flow rate in the reference state. That is, in FIG. 6, for example, a flow rate ratio of 85 [%] indicates that the flow rate is reduced by 15 [%] with respect to the reference state. This flow rate ratio can be derived by calculation or actual measurement.

[Duty ratio]
Further, the “duty ratio” in the present embodiment refers to the ratio of the ON time of the current supplied to the coil 51 in FIG. In this embodiment, the current ON time 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 addition, the “flow rate variation” in the present embodiment means that the variation related to the flow rate using the fuel for adjustment (fuel pressure 0.3 MPa (temperature: 21 ° C.)) that is always in the liquid phase is suppressed within ± 2 [%]. 3σ of the measured value variation (three times the standard deviation σ) when the flow rate using two types of LPG fuel is measured using the measurement fuel injection valve.
For this measurement, the fuel injection amount per pulse is calculated by measuring the fuel injection amount for a fixed number of drive pulses in a flow meter installed upstream of the measurement fuel injection valve. At this time, the drive frequency of the measurement fuel injection valve is 50 [Hz] (= period 20 [ms]), and the duty ratio is 10 [%] (ON time: 2 [ms], OFF time: 18 [ms]). The fuel pressure of LPG fuel (propane 100%) was 2 MPa (temperature: 50 ° C.), and the fuel pressure of LPG fuel (propane 25% + butane 75%) was 0.8 MPa (temperature: 30 ° C.).

In the graph shown in FIG. 6, in order to suppress the flow resistance of LPG and to stabilize the flow rate, the flow rate ratio [%] shown on the left vertical axis in the figure is stabilized and the right vertical axis in the figure is shown. It is required that the flow rate variation [%] shown be kept low. In the present embodiment, the conditions satisfying such conditions are set such that the dead volume D / V, that is, the sum of the volumes of the space portion 33c and the space portion 33d in FIG. 4 is 0.1 to 0.15 [mm ³ ]. (The “preferable range” in FIG. 6). That is, the lower limit of the dead volume D / V is defined by the flow rate ratio [%], and the upper limit of the dead volume D / V is defined by the flow rate variation [%].
With such a configuration, the flow resistance of the LPG is suppressed, and the degree of decompression (or degree) increases immediately after the valve 30 is switched from the valve closed state to the valve open state, whereby the LPG gas-liquid two-phase state. Can be suppressed. Thus, LPG can be accurately measured in the liquid phase as much as possible, and the LPG flow rate can be stabilized.

  As described above, regarding the protrusion 33a of the elastic body 33, the present embodiment describes a case where there is a slight time delay until the shape of the protrusion 33a once deformed in the valve closed state is restored. When an elastic body having a large elastic restoring force is used, the time delay can be suppressed. In such a case, the volume of the region where LPG flows into the fuel injection hole 41b immediately after switching from the valve closed state to the valve open state is not the dead volume D / V in the valve closed state shown in FIG. The protrusion 33a substantially matches the dead volume D / V in the state shown in FIG. Therefore, it is necessary to appropriately select a target region for setting the dead volume D / V according to the elastic return performance of the elastic body.

  In the present embodiment, the fuel injection hole 41b shown in FIG. 4 has a structure as shown in FIG. Here, FIG. 7 shows an enlarged view showing the configuration of the protruding surface 43 formed on the inlet side of the fuel injection hole 41b. As shown in FIG. 7, in the present embodiment, the fuel injection hole 41b has an inlet diameter D that is equal to or smaller than the value obtained by adding 0.2 [mm] to the inner diameter d1 of the fuel injection hole 41b. The inner peripheral surface on the side is formed on a protruding surface 43 that protrudes toward the axial center of the fuel injection hole. This projecting surface 43 is a projecting surface (chamfered portion) in which the nominal radius of round corners, the so-called corner R, is 0.1 [mm] or less in the space portion 33d (the region until the inner diameter becomes constant). Configured as This projecting surface 43 corresponds to the “projecting surface” in the present invention.

  According to such a configuration of the fuel injection hole 41b, the corner R of the projecting surface 43 can be suppressed as small as possible, and the fuel in the valve open state can be compared with a configuration in which the corner R is larger than 0.1 [mm]. When the LPG flows through the introduction path (the fuel introduction path 42 in FIG. 2) into the fuel injection hole formed in the axial direction intersecting with the extending direction of the fuel introduction path, the fuel introduction path is fueled. It can be used as a sufficient run-up section for stirring. In addition, as compared with the configuration in which the corner R of the projecting surface 43 is larger than 0.1 [mm], it is possible to suppress the space portion volume from being enlarged at the inflow port. Therefore, it is possible to suppress the formation of the gas-liquid two-phase state of LPG, and even when the gas-liquid two-phase state of LPG is formed, a stable (homogenized) ratio is achieved. A gas-liquid two-phase state can be formed. Thus, the LPG measurement in the fuel injection hole 41b is stabilized, and the flow rate can be further stabilized.

In the above embodiment, the space volume is increased at the inflow port by providing the projecting surface 43 with the corner R of 0.1 [mm] or less on the inflow side of the fuel injection hole 41b. Although the case where it suppresses was described, in this invention, in order to achieve the said objective, the protruding surface of the structure different from the protruding surface 43 can also be used. Here, the configuration of the protruding surface (corresponding to the “projecting surface” in the present invention) of another embodiment will be described with reference to FIGS.
The projecting surface 44 shown in FIG. 8 is configured as an elliptical corner in the space 33d (a region until the inner diameter becomes constant) instead of a round corner like the projecting surface 43 shown by a two-dot chain line in the drawing. The Further, the projecting surface 45 shown in FIG. 9 has an inclined surface (inclination angle θa of the first inclined surface, second inclined surface) of the two-step inclined structure in the space portion 33d (a region until the inner diameter becomes constant). Of the inclination angle θb). Further, the projecting surface 46 shown in FIG. 10 is configured as an inclined surface (inclination angle θc) having a one-step inclined structure formed over the space portion 33d and a region downstream thereof. These projecting surfaces 44 to 46 are projecting surfaces formed by causing the inner peripheral surface on the inlet side to project toward the axial center in the same manner as the projecting surface 43. In the present invention, the fuel injection hole only needs to have a protruding surface whose inner peripheral surface on the inlet side protrudes toward the axial center of the fuel injection hole. A configuration including 46 and having various projecting surfaces can be used.

In the present embodiment, as shown in FIG. 4, when the front end surface 32 c of the contact portion 32 b contacts the contact surface 41 a of the valve seat body 41, the elastic body 33 and the valve front end portion 32 (the valve 30 ) And the valve seat body 41 (valve seat 40), LPG in a liquid state is stored in a space (region) 33b. The liquid LPG stored in the space 33b is heated and vaporized by heat generated from the internal combustion engine. When the LPG in the liquid state stored in the space portion 33b is vaporized, the pressure in the space portion 33b increases, and the sealing effect by the elastic body 33 may be reduced.
Therefore, in the present embodiment, a configuration is used in which a notch portion 32d that communicates the space portion 33b and the groove portion 41c is formed on the distal end surface 32c of the contact portion 32b. For this reason, when the valve 30 (valve tip portion 32) contacts the valve seat 40 (valve seat body 41), the LPG stored in the space portion 33b can be released to the groove portion 41c side.
Therefore, when the fuel injection hole 41b is closed, it is possible to prevent a decrease in the sealing effect of the elastic body 33 due to an increase in pressure in the space 33b, and to prevent the outflow of LPG into the fuel injection hole 41b. it can.

  The present invention is not limited to the configuration described in the above embodiment, and various changes, additions, and deletions are possible according to the type of fuel, the specifications of the fuel injection valve, and the like.

In the above embodiment, the first constituent requirement for setting the volume of the dead volume D / V formed in the valve closed state shown in FIG. 4 in the range of 0.1 to 0.15 [mm ³ ], and the fuel injection A protrusion that makes the inlet diameter of the hole 41b equal to or less than the value obtained by adding 0.2 [mm] to the inner diameter of the fuel injection hole 41b, and the inner peripheral surface on the inlet side protrudes toward the axial center of the fuel injection hole 41b. Although the fuel injection valve 10 having the second constituent element formed on the surface is described, the present invention includes at least one of the first constituent element and the second constituent element in order to stabilize the flow rate. It is sufficient to use a fuel injection valve.

Moreover, in the said embodiment, although the elastic body 33 was provided in the valve | bulb 30, in this invention, an elastic body can also be provided in the valve seat 40. FIG. Further, the case where a rubber material is used as the elastic body 33 has been described. However, if the fuel injection valve can be closed by contacting the elastic body and the valve seat or the elastic body and the valve, elastic bodies of various materials and structures are used. be able to. For example, an elastic body made of a resin material can be used. An annular elastic body can also be used. Or the elastic body of the shape (for example, spherical shape) which can contact | abut to the upstream edge part of a fuel-injection hole can also be used.
Further, the valves and valve seats in the present invention are not limited to the valves 30 and valve seats 40 having the configurations described in the embodiments, and various configurations of valves and valve seats can be used. For example, a valve seat having a contact surface with which the elastic body contacts the valve is used, but a valve seat having a contact surface with which the elastic body contacts and a contact surface with which the valve contacts can be used.

  Moreover, although the fuel injection valve which injects liquefied petroleum gas (LPG) in a liquid state was demonstrated in the said embodiment, this invention is fuel which injects liquefied gas fuels, such as liquefied natural gas (LNG), in a liquid state. The present invention can be applied to a construction technique of an injection valve, and further, a fuel injection valve that injects various fuels other than liquefied gas fuel.

1 is a longitudinal sectional view of a fuel injection valve 10 that is an embodiment of a fuel injection valve of the present invention. It is an enlarged view of the part shown by W of the fuel injection valve 10 in FIG. 1, Comprising: The case where the valve 30 exists in a valve open state is shown. FIG. 2 is an enlarged view of a portion indicated by W of the fuel injection valve 10 in FIG. 1 and shows a case where the valve 30 is in a valve closing operation process. It is an enlarged view of the part shown by W of the fuel injection valve 10 in FIG. 1, Comprising: The case where the valve 30 exists in a valve closed state is shown. It is a figure which shows the cross-sectional structure in the VV line | wire in FIG. It is a graph which shows the correlation with dead volume D / V [mm < ³ >] and flow rate ratio [%], and the correlation with dead volume D / V [mm < ³ >] and flow volume variation [%]. It is an enlarged view which shows the structure of the protruding surface 43 formed in the inflow port side of the fuel injection hole 41b in FIG. It is an enlarged view which shows the structure of the protruding surface 44 of another embodiment. It is an enlarged view which shows the structure of the protruding surface 45 of another embodiment. It is an enlarged view which shows the structure of the protruding surface 46 of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel injection valve 20 Main body 21 Fixed core part 21a Fuel path 22 Support part 23 Sleeve 24 Filter 30 Valve (valve body)
31 Valve body 31a Fuel passage 31b Communication hole 32 Valve tip 32a Recess 32b Contact 32c Tip 32d Notch 33 Elastic body 33a Projection 33b, 33c, 33d Space 35 Spring adjuster 35a Fuel passage 36 Spring 40 Valve seat 41 Valve seat body 41a Contact surface 41b Fuel injection hole 41c Groove portion 41d Fuel passage 42 Fuel introduction passage 43, 44, 45, 46 Projecting surface 50 Drive portion 51 Coil

Claims (3)

A valve seat having a fuel injection hole and a valve capable of contacting the valve seat, and the inlet of the fuel injection hole is closed when the valve is in contact with the valve seat, The fuel injection valve is configured such that when the valve released from contact is opened, the inlet of the fuel injection hole is opened, and when the valve is closed, a partition region defined by the mutually facing surfaces of the valve and the valve seat is formed. And
The partition region includes a first space portion formed outside the fuel injection hole and a second space portion formed from the inlet to a portion having a constant inner diameter in the fuel injection hole. A fuel injection valve characterized in that the volume occupied by the space portion and the second space portion is 0.1 to 0.15 [mm ³ ]. The fuel injection valve according to claim 1,
The fuel introduction path formed by the mutually facing surfaces of the valve and the valve seat when the valve is opened is formed in a longitudinal shape in a direction intersecting the axial direction of the fuel injection hole, and the fuel flowing through the fuel introduction path is It is configured to flow from outside the fuel injection hole into the fuel injection hole,
The fuel injection hole has an inlet diameter equal to or smaller than a value obtained by adding 0.2 [mm] to the inner diameter of the fuel injection hole, and the inner peripheral surface on the inlet side faces toward the axial center of the fuel injection hole. A fuel injection valve formed on a protruding protruding surface. A valve seat having a fuel injection hole and a valve capable of contacting the valve seat, and the inlet of the fuel injection hole is closed when the valve is in contact with the valve seat, When the valve is released, the inlet of the fuel injection hole is opened, and when the valve is opened, the fuel that has flowed through the fuel introduction path formed by the opposing surfaces of the valve and the valve seat is outside the fuel injection hole. A fuel injection valve configured to flow into the fuel injection hole from
The fuel introduction path is formed in a longitudinal shape in a direction intersecting the axial direction of the fuel injection hole, and the fuel injection hole has an inlet diameter of 0.2 [ mm] or less, and the inner peripheral surface on the inlet side is formed as a protruding surface protruding toward the axial center of the fuel injection hole.

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