JP3977620B2 - Fuel injection valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection valve used in an engine fuel injection device.
[0002]
[Prior art]
For example, in a common rail fuel injection device for a diesel engine, a two-way solenoid valve (or a three-way solenoid valve) is generally used as a fuel injection valve. In this case, the high pressure fuel is introduced into the pressure control chamber provided on the back surface of the valve body, and the high pressure fuel (hydraulic pressure) in the pressure control chamber is leaked to the low pressure side for each injection, thereby realizing the valve opening operation of the valve body. (For example, JP-A-10-18934). Therefore, a high-pressure fuel leak occurs at every injection. In addition, high-pressure fuel leaks also in the valve body sliding portion.
[0003]
On the other hand, in recent years, liquefied gases such as DME (dimethyl ether) and LPG (liquefied petroleum gas) with additives for improving cetane number have been considered as alternative fuels for diesel oil, taking into account the vaporization, ignition and combustion properties of fuel, and emissions. The use of fuel has been studied (in the following description, the term LPG refers to a substance added with a cetane number improver unless otherwise indicated). When liquefied gas fuel is used, the amount of fuel leaked from the fuel injector tends to increase particularly, and a device for collecting the fuel leaked from the fuel injector is required. For example, as disclosed in Japanese Patent Application Laid-Open No. 11-22590, there are a purge tank for recovering vaporized liquefied gas fuel, and a compression pump for compressing and liquefying liquefied gas fuel (gas) in the purge tank. Necessary. For this reason, there arises a problem of increasing the cost as a fuel injection device.
[0004]
Therefore, in order to prevent fuel leakage, it is conceivable to employ a so-called direct-acting fuel injection valve in which the valve element is directly moved by an electromagnetic solenoid (actuator). The configuration is shown in FIG.
[0005]
In FIG. 5, a valve body 101 has an elongated shape extending in the vertical direction in the figure, and an armature 102 is fixed to the upper end of the valve body 101 by means such as laser welding. The casing 104 and the valve body 105 are provided with holes 104a and 105a, and the valve body 101 is accommodated in the holes 104a and 105a. A stator 106 is provided opposite to the armature 102. When the armature 102 is attracted to the stator 106 when the coil 107 is energized, the valve body 101 opens from the valve closing position shown in the figure against the biasing force of the spring 108. Move to valve position. Thereby, the injection hole 109 is opened, and high-pressure fuel supplied from a common rail or the like is injected. In the configuration of FIG. 5 described above, no fuel leak occurs, so that a fuel recovery device (purge tank, compression pump, etc.) for the leaked fuel is not necessary, and cost increase can be suppressed.
[0006]
[Problems to be solved by the invention]
In an engine mounted on a vehicle, for example, the fuel injection valve is replaced every approximately 100,000 km. In this case, in order to reduce the cost, it is conceivable to remove the fastening nut 110 of the fuel injection valve 100 and replace only the nozzle portion 103 at the tip of the injection valve. However, the armature 102 is fixed to the valve body 101, and the diameter of the armature 102 is usually larger than the diameter of the hole 104a. This is to obtain sufficient electromagnetic performance. Therefore, when replacing the nozzle portion 103, not only the removal nut 110 is removed but also the electromagnetic solenoid portion 111 must be disassembled. As a result, maintenance is poor and improvement is desired.
[0007]
The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a fuel injection valve capable of realizing a structure with good maintainability in an actuator direct acting fuel injection valve. It is to be.
[0008]
[Means for Solving the Problems]
The fuel injection valve according to claim 1, wherein the armature is attracted by the stator when the coil is energized, and the valve member integrated with the armature moves accordingly to open the injection hole, so-called actuator direct acting fuel injection valve It has a configuration. Further, in this configuration, in particular, the valve member is divided into a rod portion and a valve body portion, and these are connected by a connecting member. In this configuration, when the armature is attracted to the stator when the coil is energized, the valve body part moves together with the movement of the rod part, and the nozzle hole is opened and closed. Moreover, the rod part is accommodated in the first casing member and the valve element part is accommodated in the second casing member in a connected state of the rod part, the valve body part, and the connecting member.
[0009]
According to the above configuration, if the first and second casing members are disassembled and the connecting member is further detached, only the valve body portion excluding the rod portion can be removed. Therefore, when it is going to replace | exchange a valve body part after long-term use of a fuel injection valve, the workability | operativity improves. As a result, a structure with good maintainability can be realized in the actuator direct acting fuel injection valve.
[0010]
When the valve member is constituted by the two members including the rod portion and the valve body portion as described above, the valve lift amount (air gap amount between the armature and the stator) varies due to variations in processing accuracy of the respective members. It is possible. Therefore, in the invention of claim 1, Ru Tei is interposed a shim member for spacing adjustment between the rod portion and the valve body portion. Further, the connecting member is constituted by a fixture having a telescopic function. In this case, since the connecting member has an expansion / contraction function, even if the thickness of the shim member is changed, it can be appropriately handled.
[0011]
In the first aspect of the invention, as described in the second aspect , the rod portion and the valve body portion have a flange portion protruding outward at the connecting portion, and the connecting member includes the rod portion and the valve portion. It consists of a pair of engaging parts engaged with the collar part of a body part, and the expansion-contraction part provided between these pair of engaging parts. In this case, in particular, as described in claim 3 , the expansion / contraction part of the connecting member is preferably provided with a slit so as to be expandable / contractable in the axial direction of the valve member. According to the structure of Claims 2 and 3, a structure suitable as a connecting member (fixing tool) can be realized.
[0012]
In the invention according to claim 4 , the opposing surfaces of the connecting portions of the rod portion and the valve body portion each form a flat surface, and a flat plate-shaped shim member is interposed between the flat surfaces. In this case, even if the center axis of the rod part and the valve body part is slightly deviated due to a processing error or the like, the rod part and the valve body part can be connected while allowing the deviation.
[0013]
In the invention according to claim 5 , the rod portion and the valve body portion are each provided with a recess at the center of the opposing surface of the connecting portion, and a spherical shim member is interposed between the recesses. In this case, even if the connecting portion of the rod portion and the valve body portion is slightly inclined due to a processing error or the like, the rod portion and the valve body portion can be connected while allowing the inclination.
[0014]
The fuel injection valve of the present invention can be suitably embodied particularly as a fuel injection valve for liquefied gas fuel (Claim 6 ). That is, a fuel injection valve that injects liquefied gas fuel is desired to have a configuration in which leakage of the gas fuel is minimized. In the present invention, since the actuator direct-acting fuel injection valve configuration is adopted, a fuel injection valve with less fuel leakage can be realized.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the present invention is embodied in a fuel injection valve for injecting fuel into a vehicle diesel engine using liquefied gas such as DME or LPG as fuel. High-pressure fuel stored in the common rail is supplied to the fuel injection valve, and liquefied gas fuel is injected and supplied to the engine combustion chamber as the fuel injection valve opens. In particular, as the fuel injection valve, a so-called direct-acting fuel injection valve in which the valve body is directly moved by an electromagnetic solenoid (actuator) is employed.
[0016]
FIG. 1 is a drawing showing a cross-sectional structure of a fuel injection valve and a configuration around the fuel injection valve. In FIG. 1, liquefied gas fuel (DME or LPG) stored in a fuel tank 10 is discharged by a low-pressure pump (not shown), compressed to a high pressure by a high-pressure pump 11, and then supplied to a common rail 12. In the common rail 12, high-pressure fuel corresponding to the injection pressure (for example, about 30 MPa) is accumulated. Fuel injection valves 30 corresponding to the number of engine cylinders are connected to the common rail 12, and these fuel injection valves 30 are driven according to a drive signal from the ECU 20.
[0017]
Hereinafter, the configuration of the fuel injection valve 30 will be described in detail. The casing 31 and the valve body 32 constitute a first casing member and a second casing member, respectively, which are integrated by tightening a retaining nut 33. The casing 31 and the valve body 32 are provided with coaxial holes 31a and 32a. The holes 31a and 32a accommodate a rod (rod portion) 34 and a valve body (valve body portion) 35 constituting a valve member. Yes. The rod 34 has a sliding portion 34a in contact with the inner wall of the hole 31a, and the valve body 35 has a sliding portion 35a in contact with the inner wall of the hole 32a. The rod 34 and the valve body 35 slide in the vertical direction in the figure. It is free. A gap adjusting shim (shim member) 36 is interposed between the rod 34 and the valve body 35, and in this state, these members are connected by a fixture 37 as a connecting member. Here, the valve member configuration including the rod 34, the valve body 35, the shim 36, and the fixture 37 is a characteristic part of the present embodiment, and details thereof will be described later.
[0018]
A plurality of injection holes 32 b are provided at the distal end of the valve body 32, and the injection hole 32 b is closed when the distal end of the valve body 35 comes into contact with the valve body 32, and the distal end of the valve body 35 is separated from the valve body 32. By doing so, the nozzle hole 32b is opened.
[0019]
On the other hand, as a configuration of the electromagnetic solenoid portion, an armature 39 is fixed to the upper end of the rod 34 in the figure, and a first stator 40 is provided so as to face the armature 39. A second stator 42 is assembled to the first stator 40 via an insertion member 41 made of a nonmagnetic material such as SUS304, and these members are integrated in an oil-tight manner by means such as laser welding. A coil 43 is disposed on the outer periphery of the first stator 40. A spring 44 is accommodated in the first stator 40, and a valve member composed of the rod 34 and the valve body 35 is biased toward the valve closing side (the lower side in the figure) by the spring 44.
[0020]
A plate 45 is disposed between the second stator 42 and the casing 31, and the cap housing 46 is assembled to the casing 31 in this state. The plate 45 also has a function as a valve body stopper, and the lift amount of the rod 34 (valve body 35) is regulated by the upper surface of the sliding portion 34a of the rod 34 coming into contact with the plate 45.
[0021]
A suction port member 48 is assembled to the casing 31 so as to sandwich the gasket 47, and high-pressure fuel from the common rail 12 is introduced into the holes 31 a and 32 a through the suction port member 48. A bar filter 49 for preventing entry of foreign matter is press-fitted and fixed to the suction port member 48.
[0022]
Further, the hole 31 a communicates with the armature chamber 51 through the communication path 50. Therefore, high-pressure fuel acts on the rod 34 and the valve body 35 at any location, and fuel leakage such as fuel leaking from the high-pressure location to the low-pressure location at the sliding portion can be eliminated.
[0023]
In the fuel injection valve 30 configured as described above, when the coil 43 is not energized, the urging force of the spring 44 holds the valve member (the rod 34 and the valve body 35) in the valve closing position. At this time, the injection hole 32b is closed and fuel injection by the fuel injection valve 30 is stopped. When the coil 43 is energized, the armature 39 is attracted to the first stator 40, and the valve member (rod 34 and valve body 35) moves to the valve opening side (upper side in the figure) against the urging force of the spring 44. . Thereby, the nozzle hole 32b is opened, and fuel injection is performed.
[0024]
Next, the characteristic configuration of the valve member will be described in detail. FIG. 2A is an enlarged cross-sectional view showing a connecting portion between the rod 34 and the valve body 35, and FIG. 2B is a perspective view showing the configuration of the fixture 37.
[0025]
As shown in FIG. 2A, the lower end surface of the rod 34 and the upper end surface of the valve body 35 are both flat surfaces, and a flat plate-like shim 36 is interposed therebetween. The rod 34 and the valve body 35 are respectively formed with flanges 34b and 35b protruding outward, and a fixture 37 is assembled so as to engage with the flanges 34b and 35b. That is, the fixture 37 has a pair of upper and lower engaging portions 37a.
[0026]
As shown in FIG. 2B, the fixture 37 is made of a metal material such as steel, and has a planar C shape with a part of the cylinder removed. The fixture 37 can be attached from the outside at the connecting portion of the rod 34, the valve body 35 and the shim 36, and can be removed. The fixture 37 is formed with a plurality of slits (expandable portions) 37b so that the length in the axial direction is variable.
[0027]
Here, as described above, the fixture 37 is provided with an expansion / contraction function by the slit 37b. The reason will be described below.
The fuel injection valve 30 is generally replaced every predetermined travel distance of the vehicle (for example, approximately every 100,000 km travel), and considering the cost, only the nozzle portion (the valve body 32 and the valve body 35) is replaced. . At this time, in the above-described configuration in which the valve member is divided into the rod 34 and the valve body 35, the dimensional variation of each member including the rod 34 and the valve body 35 occurs, and this causes the valve lift amount (armature after replacement of the parts). -It is conceivable that the air gap between the stators) fluctuates. Therefore, it is necessary to adjust the distance by changing the thickness of the shim 36, and the fixture 37 is provided with an expansion / contraction function so that the thickness change of the shim 36 can be dealt with.
[0028]
More specifically, in FIG. 3, in which the connecting portion of the rod 34 and the valve body 35 is disassembled, the distance between the lower end surface of the casing 31 and the lower end surface of the rod 34 is L1, and the upper end surface of the valve body 32 and the valve body 35 are When the distance from the upper end surface is L2, the distance L1 is measured in a state where the rod 34 is in contact with the plate 45 (see FIG. 1). Further, the distance L2 is measured in a state where the tip of the valve body 35 is in contact with the seat portion of the valve body 32 with respect to the valve body 32 and the valve body 35 after replacement (new). Then, a necessary thickness as the shim 36 is determined from the distances L1 and L2.
[0029]
When replacing the nozzle portion (the valve body 32 and the valve body 35), the retaining nut 33 is unfastened and the valve body 32 is removed. Further, the fixture 37 is removed and the valve element 35 is removed from the rod 34. Thereby, the removal of the used nozzle portion (the valve body 32 and the valve body 35) is completed. And after measuring distance L1, L2 of FIG. 3 as mentioned above, the shim 36 corresponding to it is prepared, and a new nozzle part (the valve body 32 and the valve body 35) is further assembled | attached. Assembly may be performed in the reverse order of removal.
[0030]
According to the embodiment described in detail above, the following effects can be obtained.
When the valve body portion is to be replaced after long-term use of the fuel injection valve 30, the workability is improved. As a result, in the actuator direct acting fuel injection valve 30, a configuration with good maintainability can be realized.
[0031]
Since the shim 36 is interposed between the rod 34 and the valve body 35 and is further connected by a fixture 37 having an expansion / contraction function, even if the thickness of the shim 36 is changed, it can be appropriately handled.
[0032]
Since the rod 34, the valve body 35, and the shim 36 are in contact with each other on a flat surface and connected, even if the central axes of the rod 34 and the valve body 35 are slightly displaced due to processing errors or the like, the deviation is allowed (absorbed). However, the rod 34 and the valve body 35 can be connected.
[0033]
Since the fuel injection valve 30 has a direct-acting fuel injection valve configuration, a configuration with little fuel leakage can be realized, and can be suitably embodied as a fuel injection valve for liquefied gas fuel.
[0034]
In addition to the above, the present invention can be embodied in the following forms.
In the above embodiment, the rod 34 and the valve body 35 are connected using the flat plate-shaped shim 36, but this configuration is changed. FIG. 4 is an enlarged cross-sectional view showing a connecting portion between the rod 34 and the valve body 35. In the configuration shown in FIG. 4, the lower end surface of the rod 34 and the upper end surface of the valve element 35 both have a conical shape with a recessed central portion, and a spherical ball 61 as a shim member is interposed therebetween. Here, by changing the size (diameter) of the ball 61, the valve lift amount (air gap amount between the armature and the stator) is adjusted. In this case, even if the connecting portion of the rod 34 and the valve body 35 is slightly inclined due to a processing error or the like, the rod 34 and the valve body 35 can be connected while allowing the inclination.
[0035]
In the above embodiment, the present invention is embodied in a fuel injection valve that injects liquefied gas fuel such as DME or LPG. However, the present invention may be embodied in a fuel injection valve that injects other fuel. That is, it is embodied in a fuel injection valve that injects light oil or gasoline. In such a case as well, a configuration with good maintainability can be realized.
[Brief description of the drawings]
FIG. 1 is a view showing a cross-sectional structure of a fuel injection valve and a configuration around it.
FIG. 2 is a cross-sectional view showing a connecting portion of a rod and a valve body, and a perspective view showing a fixture.
FIG. 3 is an exploded cross-sectional view showing a connecting portion of a rod and a valve body.
FIG. 4 is a cross-sectional view showing a connecting portion of a rod and a valve body.
FIG. 5 is a sectional view showing a fuel injection valve in the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 30 ... Fuel injection valve, 31 ... Casing, 32 ... Valve body, 32b ... Injection hole, 34 ... Rod, 35 ... Valve body, 36 ... Shim, 37 ... Fixture, 39 ... Armature, 40 ... 1st stator, 43 ... Coil, 61 ... ball.

Claims (6)

In the fuel injection valve in which the armature is attracted to the stator when the coil is energized, and the valve member integrated with the armature moves accordingly to open the injection hole.
The valve member is composed of a rod portion for fixing the armature, and a valve body portion that is provided separately and coaxially with the rod portion and opens and closes the injection hole as the rod portion moves, and is detachable. Connecting the rod portion and the valve body portion with a connecting member, and housing the rod portion in the first casing member and the valve body portion in the second casing member in the connected state ,
The connecting member is constituted by a fixture having an expansion / contraction function, a shim member for adjusting a gap is sandwiched between the rod portion and the valve body portion, and the connecting member is assembled in that state. valve. 2. The fuel injection valve according to claim 1, wherein the rod portion and the valve body portion have a flange portion protruding outward at a connection portion thereof, and the connecting member is a flange portion of the rod portion and the valve body portion. The fuel injection valve which consists of a pair of engaging part engaged with 1 and the expansion-contraction part provided between these pair of engaging parts . 3. The fuel injection valve according to claim 2, wherein the expansion / contraction part of the connecting member is provided with a slit so as to be expandable / contractable in the axial direction of the valve member . The fuel injection valve according to any one of claims 1 to 3, wherein the rod portion and the valve body portion each have a flat surface facing the connecting portion, and a flat shim member interposed between the flat surfaces . The fuel injection valve according to any one of claims 1 to 3 , wherein the rod portion and the valve body portion are each provided with a recess in the center of the opposing surface of the connecting portion, and a spherical shim member is interposed between the recesses . The fuel injection valve according to any one of claims 1 to 5 , wherein liquefied gas fuel is introduced and the liquefied gas fuel is injected from the injection hole in accordance with the valve opening operation .

Images