JP2004339946A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve manufacturable simply and compactly at a low cost by effectively heating fuel and forming a heater connector integrally with a coil connector in the fuel injection valve incorporating a heater. <P>SOLUTION: This fuel injection valve 1 comprises an injection nozzle part 41 in which an injection hole 31 for injecting the fuel supplied from a fuel passage 88 is opened and closed by a valve needle 40 and an electromagnetic drive part 60 driving the valve needle 40 by energizing a coil 61. A fuel sump 87 is formed in the enlarged diameter part of a body case 33 on the upstream side of the fuel passage 88, and the heater 70 is disposed so as to surround the outer periphery of the valve needle 40. Since the heater 70 and a heater terminal connected to the heater are immersed in the fuel liquid, the heat of the heater can be efficiently transmitted to the fuel and the temperature rise of the heater terminal 15 can be suppressed. As a result, the connector 13 can be formed integrally with the coil terminal 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel injection valve for injecting fuel into an internal combustion engine, and more particularly, to a heater structure for atomizing fuel.
[0002]
[Prior art]
In recent years, regulations on exhaust gas from vehicles have been tightened, and reducing harmful components contained in exhaust gas has become a major issue. As a countermeasure, it has been known that it is effective to atomize the fuel spray injected from the injection hole of the fuel injection valve. Injecting heated fuel, the fuel is decompressed and boiled, and the fuel spray is atomized. A valve has been proposed (for example, Patent Document 1). In particular, during a cold start, the injected fuel is hard to atomize, and harmful components in the exhaust gas, for example, components such as HC and PM, are likely to increase. It is effective in reducing components.
[0003]
[Patent Document 1]
JP-A-2002-295332
In the fuel injection valve 100 disclosed in Patent Document 1, as shown in FIG. 8, a valve member 120 for opening and closing the injection hole 110, a coil 140 for driving the valve member 120, and a heater for heating the fuel 150. A terminal 131 for supplying a current to the coil 140 is embedded in the connector 130, and a terminal 152 for supplying a current to the electrode 151 of the heater 150 is electrically connected to a terminal (not shown) of the connector 170 by a wire 153. ing.
[0005]
[Problems to be solved by the invention]
Here, power is supplied to the coil 140 and the heater 150 from separate connectors 130 and 170 for the following reason. That is, although the heater 150 is accommodated in the metal case member 160 so as not to be wet, the temperature of the case member 160 and the terminal 152 becomes high due to the heat generated by the heater 150. For this reason, it is difficult to accommodate the terminal 152 in the connector 130 made of resin, and the electric wire 153 is taken out from the cylindrical portion 161 provided on the lid of the case member 160 and connected to the external connector 170. I was
[0006]
However, in the above configuration, the heat generated by the heater 150 is transmitted to the outside, and cannot be said to be effectively used for heating the fuel. The fact that the heater connector 170 and the coil connector 130 are separate components not only complicates the electrical wiring when the engine is mounted, but also increases the physical size and the manufacturing cost of the fuel injection valve. Was.
[0007]
An object of the present invention is to effectively transmit the heat generated by the heater to the fuel, suppress the heat transfer to the outside, and effectively heat the fuel. The present invention provides an injection valve that has a simple configuration, is compact, and can suppress the manufacturing cost.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, the fuel injection valve has an injection hole for injecting the fuel supplied from the fuel passage, and an injection nozzle portion whose opening and closing can be switched by a valve needle. An electromagnetic drive unit for generating an electromagnetic attraction force to drive the valve needle, and a heating unit for heating the fuel flowing through the fuel passage.
The injection nozzle portion has a case member in which the valve needle is housed, and introduces fuel into a gap between the case member and the outer peripheral surface of the valve needle to form a fuel pool that becomes a part of the fuel passage. Make up. The heating means is disposed in a state where the heating means is immersed in the fuel in the fuel pool.
[0009]
According to the above configuration, since the heating means is disposed in contact with the fuel liquid in the fuel reservoir, the heat of the heating means can be easily transmitted to the fuel. Therefore, it is possible to effectively heat the fuel supplied to the injection holes, and to promote atomization of the fuel during the cold start. Further, since the fuel liquid is interposed, heat transfer to other members is suppressed, and the degree of freedom in design is improved. Therefore, for example, the heater connector and the coil connector can be integrated to make the configuration compact, and the manufacturing cost can be suppressed.
[0010]
In the fuel injection valve according to the second aspect, the diameter of a part of the case member accommodating the valve needle is enlarged, and a gap between the enlarged diameter portion and the outer peripheral surface of the valve needle is used as the fuel reservoir. Further, the heating means is arranged so as to surround the outer periphery of the valve needle, and the space on the inner peripheral surface side and the space on the outer peripheral surface side of the heating means communicate with each other.
[0011]
Specifically, by providing an enlarged diameter portion around the valve needle, disposing the heating means, and filling the fuel, the heating means can be easily immersed in the fuel reservoir. At this time, by allowing the space on the inner peripheral surface side and the space on the outer peripheral surface side of the heating means to communicate with each other, fuel can flow through both spaces, and the fuel can be efficiently heated.
[0012]
According to a third aspect of the present invention, in the fuel injection valve, a base end portion of the terminal connected to the heating means is disposed so as to be immersed in the fuel in the fuel reservoir.
[0013]
According to the configuration, by bringing the base end of the terminal into contact with the fuel liquid, it is possible to suppress a rise in the temperature of the one end. Therefore, it is possible to suppress the temperature of the other end of the terminal from becoming high due to the heat conduction from the one end, so that, for example, the heater connector can be integrally formed with the coil connector.
[0014]
According to a fourth aspect of the present invention, the fuel injection valve includes a heat absorbing means for absorbing heat from the terminal between a base end and a distal end of the terminal connected to the heating means.
[0015]
According to the above configuration, heat conduction from the base end is further suppressed by the heat absorbing means, so that the effect of suppressing a rise in temperature at the distal end of the terminal can be enhanced.
[0016]
According to a fifth aspect of the present invention, there is provided a fuel injection valve provided with an integrated connector for accommodating a distal end of a terminal connected to the heating means and a distal end of a terminal for energizing a coil of the electromagnetic drive unit.
[0017]
According to the above configuration, the power supply unit for the heating unit and the power supply unit for the electromagnetic drive unit can be integrated into one connector. Therefore, the configuration is simplified, the size can be reduced, and the manufacturing cost can be reduced. .
[0018]
A fuel injection valve according to a sixth aspect of the present invention is configured such that a terminal connected to the heating means is divided into two members, a base end side and the distal end side. And, the member on the base end side is provided in a valve sub-assembly for housing the valve needle, and the member on the distal end side is provided in a coil assembly for housing the coil, and the coil assembly and the valve sub-assembly are assembled. Thereby, the two members constituting the terminal are electrically connected.
[0019]
When the terminal for energizing the heating unit and the terminal for energizing the coil are integrated into an integrated connector, the terminal for energizing the heating unit is divided into two, and one of the terminals for the coil is connected to the terminal for the coil. The terminal can be resin-molded in advance to form a connector. By assembling this as a coil assembly with the valve subassembly, the fuel injection valve can be easily manufactured, and the two members can be connected to form the terminal.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
(1st Embodiment)
FIG. 1 shows a fuel injection valve structure according to a first embodiment of the present invention. In FIG. 1, a fuel injection valve 1 includes a body pipe 10, a housing 20, a nozzle body 30, a body case 33 as a case member, a valve needle 40 as a valve member, and an injection nozzle that opens and closes an injection hole 31 to inject fuel. It comprises a part 41, an electromagnetic drive part 60 for driving the valve needle 40, a heater 70 as heating means, and the like.
[0021]
The body pipe 10 is inserted and fixed in the upper end opening of the housing 20 in which the base end (the upper end in the figure) of the valve needle 40 is accommodated. The body pipe 10 has a substantially cylindrical shape, and accommodates a fixed iron core 53 and a core 52 inside the cylinder from above in the figure. The fixed iron core 53 has a cylindrical shape, and houses therein a spring 51 and an adjusting pipe 54 for adjusting the urging force thereof. The core 52 located opposite to the lower surface of the fixed core 53 is formed of a magnetic material, and the core 52 and the fixed core 53 can abut. The core 52 has a cylindrical shape with two stages of large and small diameters, and the lower end of the small diameter is fixed to the base end of the valve needle 40 by laser welding or the like, and can be moved up and down integrally.
[0022]
The body pipe 10 includes a magnetic part and a non-magnetic part, and is formed of, for example, a composite magnetic material. The body pipe 10 is integrally formed in the order of the first magnetic part 10a, the non-magnetic part 10b as a magnetic resistance part, and the second magnetic part 10c from the lower injection nozzle part 41 side. The first magnetic part 10a and the second magnetic part 10c are magnetized, and the non-magnetic part 10c is made non-magnetic by heating a part of the body pipe 10. The non-magnetic portion 10b prevents the magnetic flux from short-circuiting between the first magnetic portion 10a and the second magnetic portion 10c.
[0023]
The spring 51 has one end (upper end in the drawing) abutting on the adjusting pipe 54 and the other end (lower end in the drawing) abutting on the step of the core 52, and is held therebetween. The spring 51 urges the valve needle 40 in the direction of the injection hole 31, that is, in the valve closing direction, and the load of the spring 51 can be changed by adjusting the amount of press-fit of the adjusting pipe 54.
[0024]
The inside of the cylinder of the adjusting pipe 54 and the inside of the cylinder of the fixed core 53 and the core 52 are a fuel passage 81 and a fuel passage 82 through which fuel can flow, respectively. The fuel passage 81 is connected to a fuel introduction pipe 21 fixed to an upper end of the body pipe 10. Further, a fuel passage hole 84 through which fuel passing through the fuel passages 81 and 82 can flow is formed through the lower end side wall of the core 52. Therefore, fuel introduced from the fuel introduction pipe 21 through the filter 22 is supplied to the fuel passage 83 in the housing 20 through the fuel passages 81 and 82 and the fuel circulation hole 84.
[0025]
The injection nozzle portion 41 includes the nozzle body 30 housed in the lower half of the body case 33 having a large and small two-stage diameter, the valve needle 40 and the like. The body case 33 is fixed to the lower end of the housing 20 by laser welding or the like, and the tip of the valve needle 40 (the lower end in the figure) is located inside the nozzle body 30. An injection hole 31 is formed to penetrate a tip portion (a lower end portion in the figure) of the nozzle body 30, and a valve seat portion 32 is provided on an inner peripheral portion of the nozzle body 30 on the inlet side of the injection hole 31. The valve needle 40 has an abutting portion 42 that can be seated on the valve seat portion 32. When the contact portion 42 is seated on the valve seat portion 32 and the injection hole 31 is closed, the fuel injection is shut off.
[0026]
The electromagnetic drive device 60 is disposed on the outer peripheral side of the body pipe 10 so as to surround the fixed iron core 53. The electromagnetic drive device 60 includes a coil assembly 11, a yoke 12 made of a magnetic material constituting a magnetic circuit, a fixed iron core 53 in the body pipe 10, a core 52, and the like. The coil assembly 11 includes a coil 61 and a bobbin 62 around which the coil 61 is wound. When the coil 61 is energized, an electromagnetic attractive force is generated in the fixed iron core 53, and the valve needle 40 is attracted together with the core 52 upward in FIG. 1.
[0027]
A connector 13 is formed on the outer periphery of the coil assembly 11 by resin molding. A coil terminal 14 electrically connected to the coil 61 and a heater terminal 15 electrically connected to the heater 70 are embedded in the connector 13. The coil terminal 14 and the heater terminal 15 are connected to an engine control device (not shown), and a predetermined current value output from the engine control device according to the operating condition of the engine is applied to the coil terminal 14 and the heater terminal 15.
[0028]
The heater 70 has a cylindrical shape and is disposed in the upper half of the body case 33 as an enlarged diameter portion so as to surround the outer periphery of the valve needle 40. A concave portion (not shown) is provided at the upper end of the heater 70, and a heater fixing jig 71 is fitted in the concave portion. The heater fixing jig 71 is fixed in the lower end opening of the housing 20 by laser welding or the like. The space in the upper half part of the body case 33 is a fuel reservoir 87, which communicates with a fuel passage 88 in the nozzle body 30 by a passage 89 formed in a stepped portion of the body case 33. The fuel reservoir 87 is divided into an inner peripheral surface side and an outer peripheral surface side by installing the heater 70, and a fuel passage 86 formed between the inner peripheral surface of the heater 70 and the outer peripheral surface of the valve needle 40 is not shown. A passage or a passage 89 communicates with the fuel reservoir 87 on the outer peripheral side. The upper end side of the fuel passage 86 communicates with a fuel passage 85 in the heater fixing jig 71.
[0029]
The heater 70 is formed of, for example, a ceramic heater, and has a known structure in which a heating resistor is sintered with ceramic and integrally formed into a cylindrical shape. Since the heater 70 made of ceramic or the like and the surrounding members such as the housing 20 made of metal have different linear expansion coefficients, a difference in thermal expansion occurs when the heater 70 generates heat, and the heater 70 has cracks and wobble. There is concern about the occurrence. Therefore, the heater 70 is biased and fixed downward in the figure by a dish-shaped spring 73 via a pedestal 72. By doing so, even if a difference in thermal expansion occurs between the heater 70 and the surrounding member made of metal due to the heat generated by the heater 70, the spring 73 can absorb and absorb the expansion and contraction of the spring 73.
[0030]
The heater terminal 15 is fixed to the heater 70 by welding or the like. The base end of the heater terminal 15 is located in the fuel reservoir 87, and the tip end extends into the connector 13 through a through hole 74 opened in the metal housing 20 and is taken out. The through hole 74 is sealed, for example, with a hermetic seal 75 using insulating glass. The hermetic seal 75 seals the inside and outside of the housing 20 and insulates the housing 20 from the heater terminal 15. In addition, the metal housing 20 functions as a heat absorbing means, and suppresses a temperature rise at the distal end side of the heater terminal 15 due to heat conduction from the base end side.
[0031]
Next, a procedure for assembling the fuel injection valve 1 of the present embodiment will be described. First, the valve subassembly A shown in FIG. 2 is manufactured. The valve subassembly A fixes the body pipe 10 that houses the core 52, the fixed iron core 53, and the like at the upper end side of the housing 20, and the body case 33 that houses the needle valve 40, the heater 70, the nozzle body 30, and the like at the lower end side. It is constituted by. Next, as shown in FIG. 3, after assembling the coil assembly 11 constituting the electromagnetic drive device 60 from above in the figure, the yoke 12 is fixed so as to cover the outer peripheral portion of the coil assembly 11, and the valve assembly B and I do. Thereafter, the connector 13 is molded by resin molding so as to cover the outer periphery of the coil assembly 11, and the fuel injection valve 1 of FIG. 1 is completed. The detailed configuration of each assembly is as described above and will not be described.
[0032]
In the above configuration, when a current is applied to the coil terminal 14, an electromagnetic attractive force is generated in the fixed iron core 53, and the core 52 and the valve needle 40 connected to the core 52 are attracted upward in FIG. The valve is opened. The fuel passing through the fuel passages 81, 82, 84 is formed between the fuel passage 83 of the housing 20, the fuel passage 85 formed on the inner periphery of the pedestal 72, and the inner peripheral surface of the heater 70 and the valve needle 40. Through a fuel passage 86 or from a fuel passage communicating the inner peripheral surface side and the outer peripheral surface side of the heater 70 (not shown), a fuel reservoir 87 formed by the body case 33 and the outer peripheral surface of the heater 70, a passage 89, The fuel is guided to the fuel passage 88 inside the nozzle body 30. The fuel in the fuel passage 88 is injected from the injection hole 31 through a fuel passage formed between the valve seat portion 32 and the contact portion 42 as the valve needle 40 moves upward.
[0033]
Here, when a current is applied to the heater terminal 15 during a cold start or the like, the heater 70 generates heat, and the fuel in the fuel passage 86 and the fuel reservoir 87 is heated. Therefore, since the heated fuel can be injected from the injection holes 31, atomization is promoted and harmful components contained in the exhaust gas can be reduced.
[0034]
Moreover, since the heater 70 is immersed in the fuel liquid flowing through the fuel reservoir 87 and the fuel passage 86, it is possible to efficiently heat the fuel while suppressing heat radiation to the outside. Furthermore, the heater terminal 15 has its base end immersed in the fuel liquid in the fuel reservoir 87 and is unlikely to rise in temperature. Further, since the inside of the housing 20 serving as a heat absorbing portion is provided, the tip end is unlikely to become hot. . Therefore, it can be accommodated in the connector 13 integrated with the coil terminal 14.
[0035]
Since the coil terminal 14 electrically connected to the coil 61 and the heater terminal 15 electrically connected to the heater 70 are integrated into one connector 13, only one connector is connected to the fuel injection valve. And electrical wiring can be simplified. In addition, in the conventional configuration shown in FIG. 8, since the connectors at two locations are combined into one, the physical size of the fuel injection valve becomes compact, and the manufacturing cost can be reduced.
[0036]
(2nd Embodiment)
FIG. 4 shows a second embodiment. Since the basic structure of the fuel injection valve 1 is the same as that of the first embodiment, the description will focus on the differences. The fuel injection valve 1 of the first embodiment is integrated with a resin mold after assembling the valve sub-assembly A and the coil assembly 11, but the fuel injection valve 1 of this embodiment shown in FIG. By dividing the heater terminal 15 into two members 15A and 15B and forming the connector 13 in advance, the valve subassembly A 'and the coil assembly 11' can be disassembled.
[0037]
FIG. 5 shows the structure of the valve subassembly A ′. The valve subassembly A ′ includes a needle valve 40, a heater 70, a nozzle body 30, a body case 33, a body pipe 10, and the like. The male pin 15A as a base end side member of the heater terminal 15 is electrically connected to the heater 70, and is taken out of the injection valve through a through hole 74 opened in the housing 20. The through hole 74 is sealed with a hermetic seal 75 or the like. The procedure for assembling the valve subassembly A 'is the same as in the first embodiment described above.
[0038]
FIG. 6 shows the structure and assembling procedure of the coil assembly 11 '. First, as shown in FIG. 6A, the coil 61 is wound around the bobbin 62, and the coil terminal 14 fixed to the bobbin 62 and the coil 61 are electrically connected. In the next step, as shown in FIG. 6B, a female pin 15B as a distal end side member of the heater terminal 15 is fixed to a fixing portion 63 extending from the lower end of the bobbin 62 by heat welding or the like. Then, as shown in FIG. 6C, the outer periphery of the coil 61, the bobbin 62, the coil terminal 14, and the female pin 15B to be the heater terminal 15 is covered with a resin mold to form the connector 13, and the coil assembly 11 'is formed. Complete.
[0039]
FIG. 7 shows the structure of a female pin 15B as a distal end side member of the heater terminal 15. The female pin 15B serving as the heater terminal 15 includes a female pin 16 for connecting to an male pin 15A as a base end side member of the heater terminal 15 provided in the valve subassembly A ', and a fixing part for fixing to the bobbin 62. 17 are formed.
[0040]
The valve subassembly A 'and the coil assembly 11' manufactured as described above are connected to the valve subassembly A 'shown in FIG. 5 from the side opposite to the injection hole 31 (upper side in the figure), as shown in FIG. It is integrated by assembling the coil assembly 11 '. The heater 70 is electrically connected by connecting the male pin 15A on the base end side of the heater terminal 15 and the female pin 15B on the distal end side.
[0041]
According to the configuration of the present embodiment, the same effect as in the first embodiment can be obtained. Further, the heater terminal 15 is divided into a male pin 15A on the base end side and a female pin 15B on the distal end side, each of which is accommodated in the valve subassembly A 'and the coil assembly 11'. 'Can be formed with a connector 13. Then, by assembling the valve sub-assembly A 'and the coil assembly 11' and connecting the male pin 15A and the female pin 15B, the heater terminal 15 can be easily formed, and the power supply unit can be completed. Can be. In this embodiment, at the time of disposal, the coil subassembly 11 'mainly composed of a resin part and the valve subassembly A' mainly composed of metal can be easily disassembled, and the recyclability is improved.
[0042]
As described above, according to the present invention, in a fuel injection valve having a built-in heater, heating of fuel can be effectively performed, and furthermore, a configuration is achieved by integrating a heater connector and a coil connector. A simple, compact, and low-cost fuel injection valve can be provided.
[Brief description of the drawings]
FIG. 1 is an overall sectional view of a fuel injection valve according to a first embodiment of the present invention.
FIG. 2 is a diagram for explaining a procedure for assembling the fuel injection valve according to the first embodiment, and is a cross-sectional view of a valve subassembly of the fuel injection valve.
FIG. 3 is a view for explaining an assembling procedure of the fuel injection valve according to the first embodiment, and is a cross-sectional view of a valve assembly of the fuel injection valve.
FIG. 4 is an overall sectional view of a fuel injection valve according to a second embodiment of the present invention.
FIG. 5 is a view for explaining a procedure of assembling the fuel injection valve according to the second embodiment, and is a cross-sectional view of a valve subassembly of the fuel injection valve.
FIGS. 6A to 6C are cross-sectional views illustrating a procedure of assembling the coil assembly according to the second embodiment.
FIG. 7 is an enlarged sectional view showing a female pin configuration serving as a heater terminal in the fuel injection valve of the second embodiment.
FIG. 8 is an overall sectional view of a conventional fuel injection valve.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel injection valve 10 Body pipe 13 Connector 14 Coil terminal 15 Heater terminal 15A Male pin (base end member)
15B female pin (tip member)
20 Housing (heat absorbing means)
30 Nozzle body 31 Injection hole 33 Body case (case member)
40 Valve needle 41 Injection nozzle part 51 Spring 52 Core 53 Fixed iron core 60 Electromagnetic drive 61 Coil 70 Heater (heating means)
74 Through-holes 81, 82, 83, 85, 86, 88 Fuel passage 87 Fuel pool

Claims (6)

An injection nozzle for forming an injection hole for injecting fuel supplied from the fuel passage, wherein the opening and closing of the injection hole can be switched by a valve needle;
An electromagnetic drive unit that drives the valve needle by generating an electromagnetic attraction force by energizing the coil;
In a fuel injection valve including a heating unit that heats fuel flowing through the fuel passage,
Fuel is introduced into a gap between the case member accommodating the valve needle and the outer peripheral surface of the valve needle to form a fuel reservoir that becomes a part of the fuel passage, and the heating means is immersed in the fuel in the fuel reservoir. A fuel injection valve, wherein the fuel injection valve is disposed in a state where the fuel injection valve is disposed. The diameter of a part of the case member in which the valve needle is accommodated is increased, and a gap between the enlarged diameter portion and the outer peripheral surface of the valve needle is formed as the fuel reservoir. The fuel injection valve according to claim 1, wherein the fuel injection valve is disposed so as to surround the heating means, and the space on the inner peripheral surface side and the space on the outer peripheral surface side of the heating means communicate with each other. 3. The fuel injection valve according to claim 1, wherein a base end of the terminal connected to the heating means is disposed in a state of being immersed in the fuel in the fuel reservoir. 4. The fuel injection valve according to claim 1, wherein a heat absorbing means for absorbing heat from the terminal is provided between a base end and a front end of the terminal connected to the heating means. The fuel injection valve according to any one of claims 1 to 4, wherein an integrated connector is provided for accommodating a distal end of a terminal connected to the heating means and a distal end of a terminal for energizing a coil of the electromagnetic drive unit. A terminal connected to the heating means is divided into two members, a base end side and a distal end side, and the base end side member is connected to a valve sub-assembly accommodating the valve needle by the distal end portion. 6. The fuel injection valve according to claim 5, wherein a member on the side is provided in a coil assembly accommodating the coil, and the two members constituting the terminal are electrically connected by assembling the coil assembly and the valve subassembly. .

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