JP4529971B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve that controls the opening / closing operation of a nozzle by a piezo actuator.

  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. The fuel injection valve includes a nozzle that opens and closes an injection 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 injection hole. (For example, refer to Patent Document 1).

By the way, a fuel injection valve 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. By inserting the piezo actuator into the injector body, the lead wire advances through the injector body, and the tip of the lead wire comes out of the injector body.

  Here, a connector for electrical connection is arranged on the side surface of the injector body. For this reason, when assembling the piezo actuator to the injector body, the two lead wires for power feeding proceed in the insertion direction of the piezo actuator, and then proceed to the lead wire take-out portion on the side surface of the injector body. That is, the lead wire is forced to change in angle from the insertion direction of the piezoelectric actuator to the lead wire extraction direction.

  The change in angle can be achieved without difficulty by taking advantage of the flexibility of the lead wire, but the lead wire needs to be advanced without bending until reaching the angle change position. In other words, the lead wires are required to have contradictory characteristics, but it has been difficult to achieve both.

  The present invention has been made in view of the above points, and it is an object of the present invention to allow a lead wire to be bent without bending when the piezoelectric actuator is assembled to an injector body, and thereafter the lead wire to be easily bent.

  The present invention is configured to take out the lead wires (21, 22) joined to the piezoelectric actuator (2) to the outside of the injector body (4) while inserting the piezoelectric actuator (2) into the injector body (4). The fuel injection valve includes a holding member (9) that is fixed to the piezo actuator (2) and prevents the lead wires (21, 22) from bending, and the holding member (9) is a longitudinal portion of the lead wires (21, 22). It is configured to be extendable and contractible in the direction.

  In this way, the lead wires (21, 22) can be advanced without bending by assembling the piezo actuator (2) to the injector body (4) with the holding member (9) extended. Then, when the piezo actuator (2) is further pushed into the injector body (4) after the tip of the holding member (9) abuts the injector body (4), for example, the holding member (9) is shortened and the lead wire In (21, 22), the length of the portion exposed from the holding member (9) is increased, and the exposed portion of the lead wire (21, 22) can be easily bent.

  In this case, if the holding member (9) is composed of a plurality of parts relatively movable in the longitudinal direction of the lead wires (21, 22), the extendable holding member (9) can be easily obtained. Can do.

  In this case, if the lead member (21, 22) is provided with two lead wire through holes (921, 922, 931, 932) in the movement holding member (92, 93), two lead wires are provided. (21, 22) can be positioned according to the polarity, so when the piezo actuator (2) is assembled to the injector body (4), each lead wire (21, 22) is guided to a predetermined take-out position. can do.

  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. FIG. 1 is a cross-sectional view of the main part showing the assembly process of the fuel injection valve according to the first embodiment of the present invention, FIG. 2 is a cross-sectional view showing the piezo actuator and the holding member of FIG. 1, and FIG. It is typical sectional drawing which shows the whole structure of a valve.

  First, the basic configuration and operation of the fuel injection valve will be described with reference to FIG. The fuel injection valve injects high-pressure fuel stored in a common rail (not shown) into a cylinder of a diesel internal combustion engine (not shown). A piezo actuator 2 that expands and contracts by electric discharge and a back pressure control mechanism 3 that is driven by the piezo actuator 2 to control 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. 3, the valve body 31 is illustrated as one component, but is actually divided into a plurality of parts.

  The substantially cylindrical injector body 4 has a first storage hole 41 extending in the axial direction of the fuel injection valve, and the piezoelectric actuator 2 and the back pressure control mechanism 3 are stored in the first storage hole 41. 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 fuel injection valve of the present embodiment will be described. As shown in FIG. 1, a male thread portion 42 for pipe connection is formed at the end (hereinafter referred to as the top) of the injector body 4 on the side opposite to the nozzle. 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 fuel injection valve.

  As described above, the injector body 4 is formed with the first cylindrical storage hole 41 extending in the axial direction of the fuel injection valve. In the injector body 4, a cylindrical second storage hole 43 having a diameter smaller than that of the first storage hole 41 is formed on the back side of the first storage hole 41 and coaxial with the first storage hole 41.

  Further, a columnar communication hole 44 that allows the second storage hole 43 to communicate with the outside of the injector body 4 is formed. The communication hole 44 is inclined with respect to the fuel injection valve 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 guide member 8 that guides the two lead wires 21 and 22 of the piezo actuator 2 to a predetermined take-out position is inserted into the communication hole 44. The guide member 8 has a first guide hole 81 and a second guide hole 82 penetrating from one end to the other end thereof, and is formed in a cylindrical shape with a heat-resistant, lightweight, and insulating resin.

  As shown in FIG. 2, the piezo actuator 2 is provided with a holding member 9 that prevents the two lead wires 21 and 22 from being bent. The holding member 9 includes a fixed holding member 91 fixed to the piezoelectric actuator 2 and a movable holding member 92 that can move relative to the fixed holding member 91.

  The fixed holding member 91 is made of resin or metal and has a cylindrical shape. The fixed holding member 91 is fixed by press-fitting one end thereof to the outer peripheral side of the piezo actuator 2.

  The movable holding member 92 has two lead wire through-holes 921 and 922 that penetrate from one end to the other end thereof, and is formed in a cylindrical shape with a resin that has high heat resistance, is lightweight, and has insulating properties.

  The lead wires 21 and 22 pass through the inside of the fixed holding member 91, further penetrate the lead wire through holes 921 and 922 of the moving holding member 92, and the leading ends of the lead wires 21 and 22 are exposed from the moving holding member 92. Yes.

  The movable holding member 92 is slidably inserted into the fixed holding member 91, and the holding member 9 expands and contracts in the longitudinal direction of the lead wires 21 and 22 by the relative movement of the movable holding member 92 and the fixed holding member 91. To do.

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

  First, as shown in FIG. 1, the guide member 8 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, in a state where the holding member 9 is extended (the state shown in FIG. 2), the lead wires 21 and 22 and the holding member 9 are inserted into the first housing hole 41 of the injector body 4, and then the main body portion of the piezoelectric actuator 2 is moved. The first insertion hole 41 is inserted so as to be pushed.

  In the process of pushing the main body portion of the piezo actuator 2 into the first housing hole 41, the holding member 9 extends until the tip of the movable holding member 92 contacts the end of the guide member 8 (see FIG. 1A). Since the lead wires 21 and 22 are almost entirely held by the holding member 9, the lead wires 21 and 22 can advance through the first storage hole 41 and the second storage hole 43 without being bent. it can.

  When the piezo actuator 2 is further pushed into the injector body 4 after the tip of the movement holding member 92 abuts against the end of the guide member 8, the movement holding member 92 is moved and held as shown in FIGS. 1 (b) and 1 (c). The member 92 enters the inside of the fixed holding member 91 and the holding member 9 is shortened, and the length of the portion exposed from the moving holding member 92 in the lead wires 21 and 22 is increased. Since the exposed portions of the lead wires 21 and 22 can be easily bent, the lead wires 21 and 22 enter the guide holes 81 and 82 of the guide member 8 and then bend in the direction of the guide holes 81 and 82. The inside of the holes 81 and 82 can be advanced.

  In the state where the two lead wires 21 and 22 are positioned according to the polarity, the piezo actuator 2 is pushed into the first storage hole 41, for example, so that the positive lead 21 is guided to the first guide hole 81, and the negative lead The wire 22 can be guided to the second guide hole 82.

  As shown in FIG. 1C, in a state where the piezo actuator 2 is pushed all the way into the first storage hole 41, the O-ring 21 attached to the piezo actuator 2 is in close contact with the second storage hole 43, and the first The space between the storage hole 41 and the second storage hole 43 is sealed.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 4 is a cross-sectional view showing a piezo actuator and a holding member in a fuel injection valve according to a second embodiment of the present invention. In the present embodiment, the configuration of the holding member 9 is different from that of the first embodiment. 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. 4, the fixed holding member 91 is formed with a flange portion 911 extending from the cylindrical portion toward the radially inward side at the end portion on the moving holding member 92 side. The movable holding member 92 is formed with a flange portion 923 extending from the cylindrical portion toward the radially outer side at the end portion on the fixed holding member 91 side. Then, the engagement between the flange portions 911 and 923 regulates the maximum protrusion amount of the movable holding member 92 and consequently the maximum length of the holding member 9.

(Third embodiment)
A third embodiment of the present invention will be described. FIG. 5 is a sectional view showing a piezoelectric actuator and a holding member in a fuel injection valve according to a third embodiment of the present invention. In the present embodiment, the configuration of the holding member 9 is different from that of the first embodiment. 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. 5, the holding member 9 includes a fixed holding member 91 fixed to the piezo actuator 2 and two movable holding members 92 and 93 that can move relative to the fixed holding member 91. .

  The first movement holding member 92 is formed in a cylindrical shape with resin or metal. The first moving holding member 92 is slidably inserted into the fixed holding member 91.

  The second movement holding member 93 has two lead wire through-holes 931 and 932 penetrating from one end to the other end thereof, and is formed in a cylindrical shape with a heat-resistant, lightweight, and insulating resin. The second movement holding member 93 is slidably inserted into the first movement holding member 92.

  The lead wires 21 and 22 pass through the inside of the fixed holding member 91 and the first moving holding member 92, and further pass through the lead wire through holes 931 and 932 of the second moving holding member 93, thereby leading the leading ends of the lead wires 21 and 22. Is exposed from the second movement holding member 93.

  Then, the movement holding member 92 and the fixed holding member 91 move relatively, and the second movement holding member 93 and the first movement holding member 92 move relatively, so that the holding member 9 becomes the lead wire 21, 22 expands and contracts in the longitudinal direction.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. FIG. 6 is a sectional view showing a piezoelectric actuator and a holding member in a fuel injection valve according to a fourth embodiment of the present invention. In the present embodiment, the configuration of the holding member 9 is different from that of the first embodiment. 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, the fixed holding member 91 has two lead wire through holes 912 and 913 that penetrate from one end to the other end thereof, and is formed in a columnar shape. The fixed holding member 91 is fixed by press-fitting one end thereof to the inner peripheral side of the piezoelectric actuator 2. The movable holding member 92 is formed in a bottomed cylindrical shape, and two lead wire through holes 921 and 922 are formed at the bottom thereof.

  The lead wires 21 and 22 pass through the lead wire through holes 912 and 913 of the fixed holding member 91 and further pass through the lead wire through holes 921 and 922 of the moving holding member 92 so that the tips of the lead wires 21 and 22 move and hold. The member 92 is exposed.

  The fixed holding member 91 is slidably inserted into the movable holding member 92, and the movable holding member 92 and the fixed holding member 91 move relative to each other, whereby the holding member 9 expands and contracts in the longitudinal direction of the lead wires 21 and 22. To do.

(Fifth embodiment)
A fifth embodiment of the present invention will be described. FIG. 7 is a perspective view showing a holding member in a fuel injection valve according to a fifth embodiment of the present invention. In the present embodiment, the configuration of the holding member 9 is different from that of the first embodiment. 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. 7, the movable holding member 92 has a disk-shaped plate portion 924 and two shafts 925 extending in parallel from the plate portion 924 toward the fixed holding member 91 side. Lead wire through holes 921 and 922 are formed.

  The fixed holding member 91 has two lead wire through holes 912 and 913 that penetrate from one end to the other end thereof, and is formed in a columnar shape. One end of the fixed holding member 91 is fixed by being press-fitted into the inner peripheral side of the piezoelectric actuator 2 (see FIG. 1). Further, two grooves 914 that slidably hold the shaft 925 of the movable holding member 92 are formed on the outer peripheral portion of the fixed holding member 91. The groove 914 corresponds to the sliding holding portion of the present invention. The groove 914 may be a hole.

  The lead wires 21 and 22 pass through the lead wire through holes 912 and 913 of the fixed holding member 91 and further pass through the lead wire through holes 921 and 922 of the moving holding member 92 so that the tips of the lead wires 21 and 22 move and hold. The member 92 is exposed.

  The shaft 925 of the movable holding member 92 is slidably inserted into the groove 914 of the fixed holding member 91, and the holding member 9 is moved relative to the lead wire 21, 22 expands and contracts in the longitudinal direction.

(Sixth embodiment)
A sixth embodiment of the present invention will be described. FIG. 8 is a perspective view showing a holding member in a fuel injection valve according to a sixth embodiment of the present invention.

  In the fifth embodiment, two shafts 925 are provided in the movable holding member 92 and two grooves 914 are provided in the fixed holding member 91. However, as shown in FIG. 8, one shaft 925 of the movable holding member 92 is provided. In addition, the number of the grooves 914 of the fixed holding member 91 may be one.

It is sectional drawing of the principal part which shows the assembly | attachment process of the fuel injection valve which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the piezoelectric actuator and holding member of FIG. It is typical sectional drawing which shows the whole structure of the fuel injection valve of FIG. It is sectional drawing which shows the piezoelectric actuator and holding member in the fuel injection valve which concern on 2nd Embodiment of this invention. It is sectional drawing which shows the piezoelectric actuator and holding member in the fuel injection valve which concern on 3rd Embodiment of this invention. It is sectional drawing which shows the piezoelectric actuator and holding member in the fuel injection valve which concern on 4th Embodiment of this invention. It is a perspective view which shows the holding member in the fuel injection valve which concerns on 5th Embodiment of this invention. It is a perspective view which shows the holding member in the fuel injection valve which concerns on 6th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Nozzle, 2 ... Piezo actuator, 4 ... Injector body, 9 ... Holding member, 21, 22 ... Lead wire.

Claims (7)

A piezo actuator (2) housed in a cylindrical injector body (4), which expands and contracts by charge and discharge;
Two lead wires (21, 22) for 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;
In the fuel injection valve configured to take out the other end of the lead wires (21, 22) to the outside of the injector body (4) while inserting the piezoelectric actuator (2) into the injector body (4),
A holding member (9) fixed to the piezoelectric actuator (2) to prevent the lead wires (21, 22) from being bent;
The fuel injection valve according to claim 1, wherein the holding member (9) is configured to be extendable and contractible in a longitudinal direction of the lead wires (21, 22). The fuel injection valve according to claim 1, wherein the holding member (9) is composed of a plurality of parts relatively movable in the longitudinal direction of the lead wires (21, 22). The holding member (9) includes a fixed holding member (91) fixed to the piezoelectric actuator (2), and a movable holding member (92, 93) movable relative to the fixed holding member (91). The fuel injection valve according to claim 2, comprising: The fixed holding member (91) is formed in a cylindrical shape, and is configured such that the movable holding member (92, 93) enters the inside of the fixed holding member (91) as the holding member (9) contracts. The fuel injection valve according to claim 3, wherein the fuel injection valve is provided. The moving holding member (92) is formed in a cylindrical shape, and is configured such that the fixed holding member (91) enters the inside of the moving holding member as the holding member (9) contracts. The fuel injection valve according to claim 3. The movable holding member (92) includes a shaft (925) extending in the longitudinal direction of the lead wires (21, 22),
The fuel injection valve according to claim 3, wherein the fixed holding member (91) includes a sliding holding portion (914) that holds the shaft (925) slidably. The movement holding member (92, 93) has two lead wire through holes (921, 922, 931, 932) through which the lead wires (21, 22) pass, respectively. The fuel injection valve according to any one of the above.

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