JP2007016686A - Fuel injection valve and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent erroneous assembling and reduce assembling man-hours when the terminal of a connector is joined to the lead of a piezo actuator. <P>SOLUTION: One end of a conductive auxiliary member 9 is joined to the core 221 of a negative pole lead 22, and the tube part 92 of the auxiliary member 9 is fitted onto the outer periphery of a coating member 212 of a positive pole lead 21 so that the core 211 of the positive lead 21 and the cylindrical part 92 of the auxiliary member 9 can be coaxially arranged at positions displaced in the axial direction of the positive pole lead 21. Two terminals 82, 83 are arranged according to this arrangement. Thus, the leads 21, 22 and the terminals 82, 83 can be joined to each other without mistaking polarities. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection valve that opens or closes a nozzle according to expansion and contraction of a piezo actuator, and a method for manufacturing the same.

  A conventional fuel injection device is configured to inject and supply high-pressure fuel stored in a common rail into a combustion chamber of each cylinder of an internal combustion engine via a fuel injection valve (hereinafter referred to as an injector). The injector includes a nozzle that opens and closes the nozzle hole with a needle and injects fuel when the valve is opened, and a piezo actuator that controls the opening and closing operation of the nozzle by controlling the pressure acting on the side of the needle opposite to the nozzle hole ( For example, see Patent Document 1).

By the way, the injector for a fuel injection device used for an internal combustion engine mounted on a vehicle is required to be miniaturized in order to improve mountability and improve fuel efficiency due to weight reduction. As one of means for realizing the above, there is one in which the shape of the injector body is changed to a top feed shape called a pencil type. In this configuration, a high-pressure fuel pipe is connected to one end (top) of the injector body in the axial direction.
JP 2002-257002 A

  However, in the case of this top feed shape, since the piezo actuator cannot be assembled from one end (top) side of the injector body, the piezo actuator is assembled from the other end side of the injector body.

  Specifically, two lead wires for power feeding are previously joined to the piezo actuator, the lead wire is first inserted into the injector body, and then the piezo actuator is inserted into the injector body. Then, by inserting the piezo actuator into the injector body, the lead wire advances in the injector body, and the tip of the lead wire comes out of the injector body.

  After the piezo actuator is assembled to the injector body, the connector terminal is joined to the lead wire of the piezo actuator. At this time, in the case of a piezo actuator, since it is necessary to connect in consideration of the electric polarity, the color and symbol of the lead wire are selected and assembled by visual inspection. Therefore, there has been a problem that erroneous assembly due to misrecognition of colors and symbols occurs, and that the number of assembling steps increases for confirmation of colors and symbols.

  The present invention has been made in view of the above points, and it is an object of the present invention to prevent erroneous assembly and reduce the number of assembly steps when a connector terminal is joined to a lead wire of a piezoelectric actuator.

  According to the first aspect of the present invention, the tip of the first power feeding means (21) and the tip of the second power feeding means (9, 22) are connected to the injector body (2) while inserting the piezo actuator (2) into the injector body (4). 4), the tip of the first power feeding means (21) is joined to the first terminal (82), and the tip of the second power feeding means (9, 22) is joined to the second terminal (83). ), The tip (211) of the first power feeding means (21) and the tip (92) of the second power feeding means (9, 22) are arranged coaxially. And

  According to this, since the tips of both power feeding means are arranged coaxially, for example, if the power feeding means on the central axis side is predetermined as the positive electrode and the power feeding means on the outer peripheral side is the negative electrode, correspondingly, By arranging a terminal to be joined to both power feeding means in a subsequent process, both the power feeding means and the terminal can be joined without wrong polarity. In addition, since it is not necessary to check the colors and symbols of both power feeding means, the number of assembling steps can be reduced.

  In the invention according to claim 2, the position of the tip (211) of the first power feeding means (21) and the position of the tip (92) of the second power feeding means (9, 22) are the first power feeding means (21) and The second power feeding means (9, 22) is shifted in the axial direction.

  According to this, in accordance with the fact that the tip position of the first power feeding means and the tip position of the second power feeding means are displaced in the axial direction, by arranging the terminals joined to both power feeding means in the subsequent process, the polarity Both feeding means and the terminal can be joined without making a mistake.

  In carrying out the invention according to the second aspect, the portion of the first terminal (82) where the tip of the first power feeding means (21) is joined and the second power feeding means (9) in the second terminal (83). , 22) the two terminals are arranged in a state in which the portion where the tip of the first power feeding means (21) and the second power feeding means (9, 22) are shifted in the axial direction.

  The invention according to claim 3 is characterized in that the outer diameter of the tip (211) of the first feeding means (21) is different from the outer diameter of the tip (92) of the second feeding means (9, 22). To do.

  According to this, corresponding to the fact that the outer diameter of the tip of the first power feeding means and the outer shape of the tip of the second power feeding means are different, by arranging the terminal of the connector to be joined to both power feeding means in the subsequent process Both power feeding means and the connector terminal can be joined without mistaken polarity.

  In carrying out the invention as set forth in claim 3, the portion where the tip of the first power feeding means (21) in the first terminal (82) is joined and the second power feeding means (9) in the second terminal (83). , 22), both terminals are arranged in a state where the portions where the tips of the two are fed are shifted in the axial direction of the first feeding means (21) and the second feeding means (9, 22).

  In a fourth aspect of the present invention, the first power feeding means is constituted by the first lead wire (21) in which the outer peripheral side of the core wire (211) is covered with the covering member (212), and the second power feeding means is the core wire. The second lead wire (22) whose outer peripheral side is covered with the covering member (222) and one end are joined to the core wire (221) of the second lead wire (22) and provided on the other end side. The cylindrical portion (92) is constituted by a conductive auxiliary member (9) attached to the outer periphery of the covering member (212) of the first lead wire (21).

  According to this, the core wire of the first lead wire and the cylindrical portion of the auxiliary member are arranged coaxially, and the invention according to claim 1 can be realized.

  In the invention according to claim 7, the insulating member (100) is disposed between the cylindrical portion (92) on the other end side of the auxiliary member (9) and the covering member (212) of the first lead wire (21). It is characterized by being.

  According to this, since not only the covering member of the first lead wire but also the insulating member is interposed between the cylindrical portion of the auxiliary member located on the outer periphery of the first lead wire and the core wire of the first lead wire, The insulation performance between the auxiliary member and the first lead wire can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each means described in a claim and this column shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described. 1 is a partial cross-sectional view of an injector for a fuel injection device according to a first embodiment of the present invention, FIG. 2 is a schematic cross-sectional view showing a schematic internal configuration of the injector of FIG. 1, and FIG. FIG. 3 (b) is a plan view of FIG. 3 (a), FIG. 4 is a perspective view showing the auxiliary member of FIG. 1 as a single unit, and FIG. 5 (a) is a diagram. FIG. 5B is a left side view of FIG. 5A. FIG. 5B is a front view showing the assembled state of the lead wire 1, auxiliary member, and terminal.

  First, the basic configuration and operation of the injector will be described with reference to FIG. The injector is for injecting high-pressure fuel stored in a common rail (not shown) into a cylinder of a diesel internal combustion engine (not shown). A piezoelectric actuator 2 that expands and contracts, and a back pressure control mechanism 3 that is driven by the piezoelectric actuator 2 and controls the back pressure of the nozzle 1 are provided.

  The nozzle 1 includes a nozzle body 12 in which an injection hole 11 is formed, a needle 13 that opens and closes the injection hole 11 in contact with and away from the valve seat of the nozzle body 12, and a spring 14 that urges the needle 13 in a valve closing direction.

  The piezo actuator 2 includes a positive lead 21 connected to a positive terminal of a power supply (not shown) and a negative lead 22 connected to a negative terminal of the power supply.

  The valve body 31 of the back pressure control mechanism 3 is driven by a piston 32 that moves following the expansion and contraction of the piezoelectric actuator 2, a disc spring 33 that biases the piston 32 toward the piezoelectric actuator 2, and a piston 32. A spherical valve element 34 is accommodated. Incidentally, in FIG. 2, the valve body 31 is illustrated as one component, but is actually divided into a plurality of parts.

  The substantially cylindrical injector body 4 is formed with a stepped columnar storage hole 41 extending in the axial direction of the injector at the center in the radial direction. The piezoelectric actuator 2 and the back pressure control mechanism 3 are formed in the storage hole 41. Is stored. Further, the nozzle 1 is held at the end of the injector body 4 by screwing the substantially cylindrical retainer 5 into the injector body 4.

  The nozzle body 12, the injector body 4 and the valve body 31 are formed with a high pressure passage 6 to which high pressure fuel is always supplied from the common rail, and the injector body 4 and the valve body 31 are connected to a fuel tank (not shown). 7 is formed.

  A high pressure chamber 15 is formed between the outer peripheral surface of the needle 13 on the nozzle hole 11 side and the inner peripheral surface of the nozzle body 12. The high pressure chamber 15 communicates with the nozzle hole 11 when the needle 13 is displaced in the valve opening direction. The high pressure chamber 15 is always supplied with high pressure fuel via the high pressure passage 6. A back pressure chamber 16 is formed on the side opposite to the injection hole of the needle 13. In the back pressure chamber 16, the above-described spring 14 is disposed.

  The valve body 31 is formed with a high-pressure seat surface 35 in a path communicating the high-pressure passage 6 in the valve body 31 and the back pressure chamber 16 of the nozzle 1, and the back of the low-pressure passage 7 in the valve body 31 and the nozzle 1. A low-pressure seat surface 36 is formed in a path communicating with the pressure chamber 16. The valve body 34 described above is disposed between the high pressure seat surface 35 and the low pressure seat surface 36.

  In the above configuration, when the piezo actuator 2 is contracted, the valve body 34 is in contact with the low pressure seat surface 36 and the back pressure chamber 16 is connected to the high pressure passage 6 as shown in FIG. Fuel pressure is introduced. The needle 13 is urged in the valve closing direction by the fuel pressure in the back pressure chamber 16 and the spring 14 to close the nozzle hole 11.

  On the other hand, when a voltage is applied to the piezo actuator 2 and the piezo actuator 2 is extended, the valve body 34 is in contact with the high pressure seat surface 35, the back pressure chamber 16 is connected to the low pressure passage 7, and the back pressure chamber 16 has a low pressure. become. The needle 13 is urged in the valve opening direction by the fuel pressure in the high-pressure chamber 15 to open the injection hole 11, and fuel is injected from the injection hole 11 into the cylinder of the internal combustion engine.

  Next, a specific configuration of the injector of this embodiment will be described. As shown in FIG. 1, a fuel inlet 42 and a male threaded portion 43 for pipe connection are formed at the end of the injector body 4 on the side opposite to the nozzle (hereinafter referred to as “top”). A high-pressure fuel pipe is connected to the top of the injector body 4 so that the high-pressure fuel is supplied from the common rail to the injector.

  As described above, the injector body 4 is formed with the cylindrical storage hole 41 extending in the axial direction of the injector at the center in the radial direction. The injector body 4 is formed with a columnar communication hole 44 that allows the storage hole 41 to communicate with the outside of the injector body 4.

  The communication hole 44 is inclined with respect to the injector axis. Specifically, the communication hole 44 is inclined so as to approach the top of the injector body 4 as it goes from the radial center side of the injector body 4 to the outside of the injector body 4.

  A stepped cylindrical guide member 8 made of resin such as nylon containing glass fiber is inserted into the communication hole 44. The guide member 8 has a hole portion 81 penetrating in the axial direction, and the two lead wires 21 and 22 of the piezoelectric actuator 2 are inserted into the hole portion 81.

  In addition, two terminals 82 and 83 made of a conductive metal are integrated with the guide member 8 by insert molding. These terminals 82 and 83 protrude from the injector outer side end face of the guide member 8. Further, an O-ring 84 is inserted into the annular groove on the outer peripheral portion of the guide member 8.

  As shown in FIG. 3, the two lead wires 21 and 22 of the piezo actuator 2 are covered with covering members 212 and 222 that are electrically insulating on the outer peripheral side of the conductive core wires 211 and 221. The positive electrode lead wire 21 is longer than the negative electrode lead wire 22, and therefore the tip position of the positive electrode lead wire 21 and the tip position of the negative electrode lead wire 22 are shifted.

  The positive electrode lead wire 21 and the negative electrode lead wire 22 are coupled by an auxiliary member 9 made of a conductive metal. As illustrated in FIG. 4, the auxiliary member 9 includes a first cylindrical portion 91 and a second cylindrical portion 92. The two cylindrical portions 91 and 92 are arranged non-coaxially and are shifted in the axial direction.

  As shown in FIG. 3, the first cylindrical portion 91 of the auxiliary member 9 is joined to the core wire 221 of the negative electrode lead wire 22 by caulking, welding, soldering, or the like. The positive lead wire 21 is inserted into the second cylindrical portion 92 of the auxiliary member 9 up to the portion of the covering member 212. Thereby, the core wire 211 of the positive electrode lead wire 21 and the second cylindrical portion 92 of the auxiliary member 9 are arranged coaxially and shifted in the axial direction of the positive electrode lead wire 21.

  Further, as shown in FIG. 5, two terminals 82 and 83 are arranged corresponding to the arrangement of the core wire 211 of the positive electrode lead wire 21 and the second cylindrical portion 92 of the auxiliary member 9. Specifically, the positive electrode terminal 82 includes a positive electrode bonding piece 821 bonded to the core wire 211 of the positive electrode lead wire 21, and the negative electrode terminal 83 is bonded to the second cylindrical portion 92 of the auxiliary member 9. 831. The positive electrode joining piece 821 and the negative electrode joining piece 831 are arranged so as to be shifted in the radial direction of the positive electrode lead wire 21 and are also arranged so as to be shifted in the axial direction of the positive electrode lead wire 21.

  The positive electrode lead wire 21 corresponds to the first power supply means of the present invention. The core wire 211 of the positive electrode lead wire 21 corresponds to the tip of the first power feeding means of the present invention. Further, the negative electrode lead wire 22 and the auxiliary member 9 constitute the second power feeding means of the present invention. The second cylindrical portion 92 of the auxiliary member 9 corresponds to the tip of the second power feeding means of the present invention. Further, the positive terminal 82 corresponds to the first terminal of the present invention. The negative terminal 83 corresponds to the second terminal of the present invention.

  Next, assembly of the piezo actuator 2 to the injector body 4 will be described.

  First, the positive electrode lead wire 21, the negative electrode lead wire 22, and the auxiliary member 9 are integrated as shown in FIG. Further, the guide member 8 in which the two terminals 82 and 83 are integrated and the O-ring 84 is mounted is inserted into the communication hole 44 of the injector body 4. At this time, the injector body 4 is not assembled except for the guide member 8.

  Next, the lead wires 21 and 22 are inserted into the storage hole 41 of the injector body 4, and subsequently the main body portion of the piezo actuator 2 is inserted into the storage hole 41.

  In the process of pushing the main body portion of the piezoelectric actuator 2 into the housing hole 41, the lead wires 21 and 22 enter the hole portion 81 of the guide member 8 and advance through the hole portion 81, and the core wire 211 of the positive electrode lead wire 21 is connected to the positive electrode terminal. The second cylindrical portion 92 of the auxiliary member 9 is similarly guided to a position facing the negative electrode bonding piece 831 of the negative electrode terminal 83.

  After the assembly of the piezo actuator 2 to the injector body 4 is completed as described above, the core wire 211 of the positive electrode lead wire 21 and the positive electrode bonding piece 821 of the positive electrode terminal 82 are bonded, and the second cylinder of the auxiliary member 9 The part 92 and the negative electrode joining piece 831 of the negative electrode terminal 83 are joined. Thereafter, a connector housing (not shown) is formed integrally with the guide member 8 by secondary molding.

  Further, the back pressure control mechanism 3 is housed in the injector body 4, and the retainer 5 is screwed into the injector body 4 to hold the nozzle 1, thereby completing the injector shown in FIG.

  According to the present embodiment, the core wire 211 of the positive electrode lead wire 21 and the second cylindrical portion 92 of the auxiliary member 9 are arranged coaxially and shifted in the axial direction of the positive electrode lead wire 21. Since the two terminals 82 and 83 are disposed, the lead wires 21 and 22 and the terminals 82 and 83 can be joined without changing the polarity. In addition, since it is not necessary to check the colors and symbols of the two lead wires 21 and 22, the number of assembling steps can be reduced.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 6A is a front view showing the configuration in the vicinity of the tip end portion of the lead wire in the injector according to the second embodiment, and FIG. 6B is a plan view of FIG. In addition, the same code | symbol is attached | subjected to the same or equivalent part as 1st Embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 6, in the present embodiment, a cylindrical insulating member 100 is disposed between the second cylindrical portion 92 of the auxiliary member 9 and the covering member 212 of the positive electrode lead wire 21. Further, the insulating member 100 extends to the position of the first cylindrical portion 91 of the auxiliary member 9.

  Accordingly, the positive lead is provided between the first cylindrical portion 91 of the auxiliary member 9 and the core wire 211 of the positive lead wire 21 and between the second cylindrical portion 92 of the auxiliary member 9 and the core wire 211 of the positive lead wire 21. Since not only the covering member 212 of the wire 21 but also the insulating member 100 is interposed, the insulating performance between the auxiliary member 9 and the positive electrode lead wire 21 can be improved.

(Other embodiments)
In the above embodiments, the tip positions of the two lead wires 21 and 22 are shifted, but the tip positions of the two lead wires 21 and 22 may be the same.

  Further, the outer diameters of the covering members 212 and 222 of the two lead wires 21 and 22 may be the same or different.

  Moreover, in each said embodiment, although the position of the core wire 211 of the positive electrode lead wire 21 and the position of the 2nd cylindrical part 92 of the auxiliary member 9 were shifted to the axial direction of the positive electrode lead wire 21, even if those positions are made the same, Good. In this case, since the outer diameter of the core wire 211 of the positive electrode lead wire 21 and the outer diameter of the second cylindrical portion 92 of the auxiliary member 9 are different, the positive electrode bonding piece 821 and the negative electrode bonding piece 831 are in the radial direction of the positive electrode lead wire 21. The positive electrode lead wire 21 is arranged without being shifted in the axial direction.

  Moreover, in each said embodiment, although the outer diameter of the core wire 211 of the positive electrode lead wire 21 and the outer diameter of the 2nd cylindrical part 92 of the auxiliary member 9 differ, those diameters may be made the same. In this case, since the position of the core wire 211 of the positive electrode lead wire 21 and the position of the second cylindrical portion 92 of the auxiliary member 9 are shifted in the axial direction of the positive electrode lead wire 21, the positive electrode bonding piece 821 and the negative electrode bonding piece 831 are The positive lead wire 21 is arranged so as to be shifted in the axial direction, and the positive lead wire 21 is arranged so as not to be shifted in the radial direction.

It is a fragmentary sectional view of the injector for fuel injection equipment concerning a 1st embodiment of the present invention. It is typical sectional drawing which shows the schematic internal structure of the injector of FIG. (A) is a front view which shows the assembly | attachment state of the lead wire of FIG. 1, and an auxiliary member, (b) is a top view of (a). It is a perspective view which shows the auxiliary member of FIG. (A) is a front view which shows the assembly | attachment state of the lead wire of FIG. 1, an auxiliary member, and a terminal, (b) is a left view of (a). (A) is a front view which shows the structure of the lead wire front-end | tip part vicinity in the injector which concerns on 2nd Embodiment, (b) is a top view of (a).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Nozzle, 2 ... Piezo actuator, 4 ... Injector body, 9 ... Auxiliary member (2nd electric power feeding means), 21 ... Positive electrode lead wire (1st electric power feeding means), 22 ... Negative electrode lead wire (2nd electric power feeding means).

Claims (10)

A piezo actuator (2) housed in a cylindrical injector body (4), which expands and contracts by charge and discharge;
A first power feeding means (21) and a second power feeding means (9, 22) for power feeding, one end of which is joined to the piezoelectric actuator (2);
A nozzle (1) that opens or closes according to expansion and contraction of the piezo actuator (2) and injects fuel when the valve is opened;
While inserting the piezo actuator (2) into the injector body (4), the tip of the first power feeding means (21) and the tip of the second power feeding means (9, 22) are arranged outside the injector body (4). Configured to take out
In the fuel injection valve, the tip of the first power feeding means (21) is joined to the first terminal (82), and the tip of the second power feeding means (9, 22) is joined to the second terminal (83). ,
A fuel injection valve characterized in that a tip (211) of the first power feeding means (21) and a tip (92) of the second power feeding means (9, 22) are arranged coaxially. The position of the tip (211) of the first power feeding means (21) and the position of the tip (92) of the second power feeding means (9, 22) are determined by the first power feeding means (21) and the second power feeding means ( 9. The fuel injection valve according to claim 1, wherein the fuel injection valve is displaced in the axial direction of 9,22). The outer diameter of the tip (211) of the first power feeding means (21) and the outer diameter of the tip (92) of the second power feeding means (9, 22) are different from each other. The fuel injection valve as described. The first power supply means includes a first lead wire (21) in which the outer peripheral side of the core wire (211) is covered with a covering member (212),
The second power feeding means is joined to the second lead wire (22) in which the outer peripheral side of the core wire (221) is covered with the covering member (222), and one end is joined to the core wire (221) of the second lead wire (22). In addition, the cylindrical portion (92) provided on the other end side is constituted by a conductive auxiliary member (9) attached to the outer periphery of the covering member (212) of the first lead wire (21). The fuel injection valve according to any one of claims 1 to 3, wherein A tube portion (91) is provided on one end side of the auxiliary member (9), and the core wire (221) of the second lead wire (22) is inserted and joined to the tube portion (91) on the one end side. The fuel injection valve according to claim 4. The cylindrical portion (91) on one end side of the auxiliary member (9) and the cylindrical portion (92) on the other end side of the auxiliary member (9) are arranged non-coaxially. The fuel injection valve described in 1. An insulating member (100) is disposed between the cylindrical portion (92) on the other end side of the auxiliary member (9) and the covering member (212) of the first lead wire (21). The fuel injection valve according to any one of claims 4 to 6. A portion of the first terminal (82) where the tip of the first feeding means (21) is joined and a portion of the second terminal (83) where the tip of the second feeding means (9, 22) is joined. The fuel injection valve according to any one of claims 1 to 7, characterized in that the first power supply means (21) and the second power supply means (9, 22) are displaced in the axial direction. A portion of the first terminal (82) where the tip of the first feeding means (21) is joined and a portion of the second terminal (83) where the tip of the second feeding means (9, 22) is joined. 9. The fuel injection valve according to claim 1, wherein the fuel injection valve is displaced in a radial direction of the first power feeding means (21). The method for manufacturing a fuel injection valve according to any one of claims 4 to 7, wherein the auxiliary member (9) is joined to a core wire (221) of the second lead wire (22), and After the cylinder part (92) on the other end side of the auxiliary member (9) is mounted on the covering member (212) of the first lead wire (21), the piezo actuator (2) is attached to the injector body (4). A method of manufacturing a fuel injection valve, wherein the fuel injection valve is inserted.

Images