JP2015129441A - fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a discharge valve drivable with small energy.SOLUTION: By a displacement transmission mechanism 5, a moving direction of a first piston 53 with extension of a piezoelectric element laminate 4 is made opposite to a moving direction of a second piston 54, and a discharge valve 32 is driven in a direction separating from a housing chamber side seat surface 311 with extension of the piezoelectric element laminate 4 which is caused by charging of electric charge. The discharge valve 32 can be therefore arranged in the housing chamber 13. Accordingly, there is no necessity of arranging a rod part, which is part of means for transmitting extension and contraction of the piezoelectric element laminate 4 to the discharge valve 32, in a discharge passage 315 as in a conventional fuel injection valve, and the discharge passage 315 can be reduced in cross section area. As a result, the pressure receiving area of the discharge valve 32 can be reduced and the discharge valve 32 can be driven with small energy.

Description

  The present invention relates to a fuel injection valve for injecting fuel into a combustion chamber of an internal combustion engine.

  Conventionally, as this type of fuel injection valve, for example, there is one described in Patent Document 1. The fuel injection valve described in Patent Document 1 includes a nozzle needle that opens and closes an injection hole, and the nozzle needle is biased toward the valve closing direction by the fuel pressure in the control chamber. The pressure of the control chamber is controlled by a discharge valve driven by the piezo element stack, thereby controlling the on / off valve operation of the nozzle needle.

  More specifically, the discharge valve opens and closes a discharge passage for discharging high pressure fuel in the control chamber to the low pressure portion. Further, a rod portion which is a part of means for transmitting the expansion and contraction of the piezoelectric element laminate to the discharge valve is disposed in the discharge passage. In addition, a seat surface with which the discharge valve contacts and separates is formed around one end side of the discharge passage. When the nozzle needle closes the nozzle hole, the discharge valve is pressed against the seat surface by a high fuel pressure.

JP 2002-322958 A

  However, in the conventional fuel injection valve, since the rod portion is disposed in the discharge passage, the cross-sectional area of the discharge passage is increased, and consequently the pressure receiving area of the discharge valve is increased. Therefore, the force that presses the discharge valve against the seat surface increases, and when starting fuel injection, a large amount of energy is required to drive the discharge valve.

  An object of this invention is to make it possible to drive a discharge valve with small energy in view of the above points.

  In order to achieve the above object, according to the first aspect of the present invention, the piezoelectric element laminate (4) disposed in the low-pressure storage chamber (13) and extending and contracting due to charge / discharge of electric charge, and the fuel storage chamber disposed in the storage chamber. Nozzle body having an oil-tight chamber (57) filled with a gas and a transmission means (5) for transmitting the expansion and contraction of the piezoelectric element laminate, and an injection hole (211) for injecting high-pressure fuel into the combustion chamber of the internal combustion engine (21), a nozzle needle (22) that reciprocates in the nozzle body and opens and closes the nozzle hole on one end side, and the other end side of the nozzle needle is slidably inserted, and the fuel pressure toward the valve closing is inserted into the nozzle needle Nozzle cylinder (24) having a control chamber (26) that acts, a storage chamber side seat surface (311) exposed in the storage chamber, a control chamber side seat surface (312) exposed in the control chamber, and fuel in the control chamber Discharge to be discharged into the containment chamber An intermediate body (31) having a passage (315) and a high-pressure supply passage (314) for supplying high-pressure fuel to the control chamber; and a reciprocating displacement disposed in the control chamber and coming into and out of contact with the control chamber side seat surface A control plate (33) that opens and closes the high-pressure supply passage, and a discharge valve (32) that is disposed in the storage chamber and is driven by the transmission means to open and close the discharge passage by contacting and separating from the storage chamber side seat surface. The transmission means is driven by the piezo element stack, and operates by receiving a first piston (53) that raises the pressure of the oil tight chamber as the piezo element stack is extended by charge charging, and the pressure of the oil tight chamber. A second piston (54) for driving the discharge valve, and the movement direction of the first piston and the movement direction of the second piston are opposite, and the discharge valve is accommodated as the piezo element stack extends. From the room side seat surface Characterized in that it is configured to be driven in the direction to be.

  According to this, since the discharge valve is driven in a direction away from the storage chamber side sheet surface as the piezo element stack is extended by charging of the charge, the discharge valve can be arranged in the storage chamber.

  Therefore, it is not necessary to dispose the rod portion, which is part of the means for transmitting the expansion and contraction of the piezoelectric element laminate to the discharge valve as in the conventional case, in the discharge passage, and the cross-sectional area of the discharge passage can be reduced.

  As a result, the pressure receiving area of the discharge valve can be reduced, and the discharge valve can be driven with small energy.

  According to the fifth aspect of the present invention, the piezoelectric element laminate (4) disposed in the low-pressure storage chamber (13) and expanding and contracting due to charge / discharge, and an injection for injecting high-pressure fuel into the combustion chamber of the internal combustion engine. A nozzle body (21) having a hole (211), a nozzle needle (22) that reciprocates in the nozzle body and opens and closes the injection hole on one end side, and the other end side of the nozzle needle are slidably inserted. A nozzle cylinder (24) having a control chamber (26) for applying fuel pressure in a valve closing direction, a storage chamber side seat surface (311) exposed to the storage chamber, and a control chamber side seat surface (312) exposed to the control chamber. ), An intermediate body (31) having a discharge passage (315) for discharging fuel from the control chamber to the storage chamber, and a high pressure supply passage (314) for supplying high pressure fuel to the control chamber, and a reciprocating displacement disposed in the control chamber. And A control plate (33) that opens and closes the high-pressure supply passage by making contact with and separating from the room-side sheet surface, and is disposed in the accommodation room, and is discharged by making contact with and separating from the accommodation room-side sheet surface as the piezoelectric element laminate expands and contracts. A discharge valve (32) that opens and closes the passage, and is configured to be driven to a position where the discharge valve abuts on the seat surface of the storage chamber when the piezoelectric element stack is extended by charge charging. It is characterized by.

  According to this, since the discharge valve is driven to a position where it comes into contact with the storage chamber side sheet surface as the piezoelectric element laminate is extended by charging the charge, the discharge valve can be arranged in the storage chamber.

  Therefore, it is not necessary to dispose the rod portion, which is part of the means for transmitting the expansion and contraction of the piezoelectric element laminate to the discharge valve as in the conventional case, in the discharge passage, and the cross-sectional area of the discharge passage can be reduced.

  As a result, the pressure receiving area of the discharge valve can be reduced, and the discharge valve can be driven with small energy.

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

It is sectional drawing which shows the structure of the fuel injection valve which concerns on 1st Embodiment of this invention. It is an expanded sectional view of the principal part of the fuel injection valve of FIG. It is sectional drawing which shows the other operating state of the fuel injection valve which concerns on 1st Embodiment of this invention. It is an expanded sectional view of the principal part of the fuel injection valve of FIG. It is sectional drawing which shows the structure of the principal part of the fuel injection valve which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the structure of the principal part of the fuel injection valve which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows the structure of the fuel injection valve which concerns on 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described.

  The fuel injection valve of this embodiment injects high-pressure fuel supplied from a common rail (not shown) into a combustion chamber of a compression ignition type internal combustion engine (hereinafter referred to as an internal combustion engine, not shown).

  As shown in FIGS. 1 to 4, the fuel injection valve includes an injector body 1, a nozzle 2, a control valve mechanism 3, a piezoelectric element laminate 4, a displacement transmission mechanism 5, and a retaining nut 6 as main components. Yes.

  A substantially bottomed cylindrical injector body 1 includes a high-pressure fuel passage 11 through which high-pressure fuel supplied from a common rail flows, a low-pressure fuel passage 12 that is connected to a fuel tank (not shown) and is always at a low pressure, and a piezoelectric element laminate. 4 and the displacement transmission mechanism 5 are formed.

  The nozzle 2 includes a substantially bottomed cylindrical nozzle body 21, a substantially cylindrical nozzle needle 22 that is slidably inserted into the nozzle body 21, a nozzle spring 23 that biases the nozzle needle 22 in a valve-closing direction, and a nozzle cylinder 24. It has.

  The nozzle body 21 is formed with a nozzle hole 211 through which high-pressure fuel is injected into the combustion chamber of the internal combustion engine, and the nozzle hole 21 is brought into contact with and separated from the nozzle body 21 by the tip (ie, the nozzle hole side end) of the nozzle needle 21. Can be opened and closed.

  A fuel reservoir chamber 25 in which high pressure fuel is always supplied from the common rail is formed in the nozzle body 21, and the high pressure fuel from the common rail flows toward the injection hole 211 through the fuel reservoir chamber 25.

  The cylindrical nozzle cylinder 24 is pressed against an intermediate body 31 (to be described later) by a nozzle spring 23, and the rear end portion (that is, the end portion on the side of the injection hole) of the nozzle needle 22 is slidably inserted into the nozzle cylinder 24. Yes.

  A control chamber 26 in which the internal fuel pressure is switched between a high pressure and a low pressure is formed in the nozzle cylinder 24. The nozzle needle 22 is urged in the valve closing direction by the fuel pressure in the control chamber 26 and is urged in the valve opening direction by the fuel pressure in the fuel reservoir chamber 25.

  The control valve mechanism 3 that controls the pressure in the control chamber 26 includes an intermediate body 31, a discharge valve 32, a control plate 33, and a plate spring 34.

  The disc-shaped intermediate body 31 is sandwiched between the injector body 1 and the nozzle body 21. In addition, the intermediate body 31 is pinched | interposed between the injector body 1 and the nozzle body 21, and the injector body 1 and the retaining nut 6 are screwed together, and the components of the fuel injection valve are integrated.

  The storage chamber side seat surface 311 on the injector body 1 side in the intermediate body 31 is exposed in the storage chamber 13. The control chamber side seat surface 312 on the nozzle body 21 side of the intermediate body 31 is exposed to the fuel reservoir chamber 25 and the control chamber 26.

  Further, the intermediate body 31 has a high pressure fuel passage 313 for communicating the high pressure fuel passage 11 of the injector body 1 and the fuel reservoir chamber 25 in the nozzle body 21, and a high pressure supply passage 314 for communicating the high pressure fuel passage 313 and the control chamber 26. And a discharge passage 315 that allows the storage chamber 13 and the control chamber 26 to communicate with each other.

  The nozzle cylinder 24 is pressed against the control chamber side sheet surface 312 by the nozzle spring 23.

  In the control chamber 26, a disc-shaped control plate 33 and a plate spring 34 that urges the control plate 33 toward the intermediate body 31 are disposed.

  In the nozzle cylinder 24, a stopper surface 241 is formed on the inner wall surface that defines the control chamber 26. The control plate 33 is configured to reciprocate between the stopper surface 241 and the control chamber side sheet surface 312.

  When the control plate 33 is in contact with the stopper surface 241, the control chamber 26 is separated into two spaces by the control plate 33. Specifically, it is separated into an intermediate body side control chamber 26a which is a space on the intermediate body 31 side, and a needle side control chamber 26b which is a space on the nozzle needle 2 side. Hereinafter, the control chamber 26, the intermediate body side control chamber 26a, and the needle side control chamber 26b are properly used as necessary.

  A communication hole 331 penetrating in the axial direction of the control plate 33 is formed in the central portion of the control plate 33 in the radial direction.

  When the control plate 33 abuts against the control chamber side seat surface 312, the high pressure supply passage 314 is closed, and the communication between the high pressure fuel passage 313 and the control chamber 26 is blocked. Further, when the control plate 33 is in contact with the control chamber side sheet surface 312, the communication hole 331 and the discharge passage 315 are in communication.

  The discharge valve 32 is disposed in the storage chamber 13 and is configured to open and close between the storage chamber 13 and the discharge passage 315 while being in contact with and away from the storage chamber side sheet surface 311.

  The piezo element laminate 4 is configured by laminating a large number of piezo elements, and is expanded and contracted by charge and discharge.

  The displacement transmission mechanism 5 as a transmission means includes a first cylinder 51, a second cylinder 52, a first piston 53, a second piston 54, a piezo spring 55, and a piston spring 56. In addition, the 1st cylinder 51 and the 2nd cylinder 52 comprise the cylinder of this invention.

  A cylindrical first cylinder hole 511 is formed in the cylindrical first cylinder 51.

  Of the space of the first cylinder hole 511, the space between the second cylinder 52 and the first piston 53 and on the outer peripheral side of the second piston 54 is an oil-tight chamber 57 filled with fuel.

  A second cylinder hole 521 that is a columnar space having a smaller diameter than the first cylinder hole 511 is formed in the cylindrical second cylinder 52.

  The first cylinder 51 is biased toward the second cylinder 52 by the piezo spring 55, and the end surface of the first cylinder 51 is pressed against the end surface of the second cylinder 52.

  The bottomed cylindrical first piston 53 is urged toward the piezo element stack 4 by a piezo spring 55 disposed between the first piston 53 and the first cylinder 51. As a result, a preload is applied to the piezoelectric element multilayer body 4, and the first piston 53 operates integrally with the piezoelectric element multilayer body 4 as the piezoelectric element multilayer body 4 expands and contracts. The first piston 53 is slidably inserted into the first cylinder hole 511.

  A first piston hole 531 having a cylindrical space is formed in the first piston 53. The first piston hole 531 has an opening on the oil-tight chamber 57 side.

  A part of the first piston hole 531 is a sliding part where the second piston 54 slides, and the remaining part of the first piston hole 531 is a spring chamber 532 in which a piston spring 56 is disposed. The spring chamber 532 is communicated with the storage chamber 13 through a communication hole 533 formed in the first piston 53. Further, the first piston end surface 534 on the opening side of the first piston 53 is exposed to the oil tight chamber 57.

  The stepped columnar second piston 54 has a smaller diameter than the first piston 53, and includes a second piston large diameter portion 541 that is slidably inserted into the first piston hole 531, and a second piston large diameter portion 541. And a second piston small-diameter portion 542 slidably inserted into the second cylinder hole 521.

  A second piston step surface 543 that is a boundary between the second piston large diameter portion 541 and the second piston small diameter portion 542 is exposed to the oil tight chamber 57.

  The distal end side of the second piston small diameter portion 542 protrudes from the second cylinder hole 521 and is located in the storage chamber 13. A discharge valve 32 is attached to the tip of the second piston small diameter portion 542.

  The second piston 54 is biased toward the storage chamber side seat surface 311 by a piston spring 56.

  Next, the operation of the fuel injection valve will be described. First, when the piezoelectric element laminate 4 is charged when the needle valve is closed as shown in FIGS. 1 and 2, that is, when the discharge valve 32 is in contact with the storage chamber side seat surface 311, The laminated body 4 extends. Accordingly, the first piston 53 is driven in a direction away from the piezo element stack 4, and the pressure in the oil-tight chamber 57 is increased by the first piston 53.

  Further, the pressure in the oil tight chamber 57 that has been increased in pressure acts on the second piston step surface 543, and the second piston 54 and the discharge valve 32 are driven toward the piezoelectric element laminate 4 side. As described above, in the fuel injection valve of the present embodiment, the movement direction of the first piston 53 and the movement direction of the second piston 54 accompanying the extension of the piezoelectric element stack 4 are reversed, and the extension of the piezoelectric element stack 4 is extended. Accordingly, the discharge valve 32 is driven in a direction away from the storage chamber side seat surface 311.

  When the discharge valve 32 is moved away from the storage chamber side seat surface 311 and the discharge passage 315 is opened by the movement of the discharge valve 32, the fuel in the discharge passage 315 flows into the storage chamber 13 and the discharge passage 315 and the intermediate body side. The pressure in the control chamber 26a decreases. Thereby, the control plate 33 is moved to the intermediate body 31 side by the pressure of the needle side control chamber 26b, rather than the force that the control plate 33 is urged toward the nozzle needle 2 side by the pressure of the intermediate body side control chamber 26a. Since the force urged toward becomes larger, the control plate 33 moves toward the intermediate body 31 side.

  As shown in FIGS. 3 and 4, the control plate 33 comes into contact with the control chamber side seat surface 312, the high pressure supply passage 314 is closed by the control plate 33, and the communication between the high pressure fuel passage 11 and the control chamber 26 is performed. Is cut off. Further, the fuel in the control chamber 26 flows out into the storage chamber 13 through the communication hole 331 and the discharge passage 315, and the pressure in the control chamber 26 is reduced. As a result, the force for urging the nozzle needle 22 in the valve closing direction is reduced, so that the nozzle needle 22 moves in the valve opening direction and fuel is injected from the injection hole 211.

  At this time, the amount of change in the length of the piezoelectric element laminate 4 is expanded by the pressure receiving area ratio between the first piston end surface 534 and the second piston step surface 543 and transmitted to the second piston 54 and the discharge valve 32.

  On the other hand, when the charge of the piezoelectric element laminate 4 is discharged in the needle open state shown in FIGS. 3 and 4, that is, when the discharge valve 32 is separated from the storage chamber side seat surface 311, the piezoelectric element laminate is discharged. 4 contracts. Accordingly, the first piston 53 urged by the piezo spring 55 follows the piezo element laminate 4 and moves toward the piezo element laminate 4 so that the pressure in the oil-tight chamber 57 decreases.

  Therefore, the second piston 54 and the discharge valve 32 move toward the intermediate body 31 by the urging force of the piston spring 56. As described above, in the fuel injection valve of the present embodiment, the movement direction of the first piston 53 and the movement direction of the second piston 54 due to the contraction of the piezo element stack 4 are reversed.

  When the discharge valve 32 comes into contact with the storage chamber side seat surface 311 and the discharge passage 315 is closed by the movement of the discharge valve 32, the outflow of fuel in the discharge passage 315 stops, and the discharge passage 315 and the control chamber 26 have the same pressure. become. Thereby, the control plate 33 is moved to the nozzle needle 2 side by the pressure of the discharge passage 315 and the high pressure supply passage 314 rather than the force that the control plate 33 is urged toward the intermediate body 31 side by the pressure of the control chamber 26. Since the force urged toward the head increases, the control plate 33 moves toward the nozzle needle 2 side.

  Then, the control plate 33 contacts the stopper surface 241, and the high-pressure fuel that has flowed into the intermediate body-side control chamber 26 a from the high-pressure supply passage 314 flows into the needle-side control chamber 26 b through the communication hole 331.

  Thus, when high pressure fuel flows into the needle side control chamber 26b, the nozzle needle 2 moves in the valve closing direction, the injection hole 211 is closed, and fuel injection is completed.

  In the present embodiment, the displacement transmission mechanism 5 causes the movement direction of the first piston 53 and the movement direction of the second piston 54 to be opposite to each other when the piezo element stack 4 is extended, so that the piezo element stack by charge charging is performed. Since the discharge valve 32 is driven in a direction away from the storage chamber side seat surface 311 as the body 4 extends, the discharge valve 32 can be disposed in the storage chamber 13.

  Accordingly, there is no need to dispose the rod portion, which is part of the means for transmitting the expansion and contraction of the piezoelectric element laminate 4 to the discharge valve 32 as in the conventional case, in the discharge passage 315, and the cross-sectional area of the discharge passage 315 is reduced. Can do.

  As a result, the pressure receiving area of the discharge valve 32 can be reduced, and the discharge valve 32 can be driven with small energy.

(Second Embodiment)
A second embodiment of the present invention will be described. In this embodiment, the configuration of the displacement transmission mechanism 5 is partly changed, and the other parts are the same as those in the first embodiment. Therefore, only the parts different from the first embodiment will be described.

  As shown in FIG. 5, the second piston 54 has a second piston large-diameter portion 541 that is slidably inserted into the first cylinder hole 511. A second piston hole 544 into which the first piston 53 is slidably inserted is formed inside the second piston large diameter portion 541. The second piston hole 544 has an opening on the piezoelectric element laminate 4 side.

  Of the second piston hole 544, a space between the bottom inner wall surface of the second piston large diameter portion 541 and the first piston end surface 534 is a first oil-tight chamber 571 filled with fuel. Of the space in the first cylinder hole 511, the space between the second cylinder 52 and the second piston step surface 543 is a second oil-tight chamber 572 filled with fuel.

  The first oil-tight chamber 571 and the second oil-tight chamber 572 are communicated with each other through an oil-tight chamber communication hole 545 formed in the second piston 54. Note that the first oil-tight chamber 571 and the second oil-tight chamber 572 constitute the oil-tight chamber of the present invention.

  In the configuration described above, when the piezoelectric element laminate 4 is charged when the needle valve is closed as shown in FIG. 5, that is, when the discharge valve 32 is in contact with the storage chamber side seat surface 311, the piezoelectric element laminate 4 is charged. The body 4 extends. Accordingly, the first piston 53 is driven in a direction away from the piezo element stack 4, and the pressure in the first oil-tight chamber 571 and the second oil-tight chamber 572 is increased by the first piston 53.

  Further, the pressure in the second oil tight chamber 572 that has been increased in pressure acts on the second piston step surface 543, and the second piston 54 and the discharge valve 32 are driven toward the piezoelectric element laminate 4 side. That is, the direction of movement of the first piston 53 and the direction of movement of the second piston 54 associated with the extension of the piezoelectric element stack 4 are reversed, and the discharge valve 32 is disposed on the storage chamber side seat surface as the piezoelectric element stack 4 extends. Driven away from 311.

  The movement of the discharge valve 32 causes the discharge valve 32 to move away from the storage chamber side seat surface 311 and the discharge passage 315 is opened.

  On the other hand, when the charge of the piezoelectric element laminate 4 is discharged in the needle open state, that is, when the discharge valve 32 is away from the storage chamber side seat surface 311, the piezoelectric element laminate 4 contracts. Accordingly, the first piston 53 urged by the piezo spring 55 follows the piezo element laminate 4 and moves toward the piezo element laminate 4, and the first oil-tight chamber 571 and the second oil-tight chamber 572 are moved. The pressure drops.

  Therefore, the second piston 54 and the discharge valve 32 move toward the intermediate body 31 by the urging force of the piston spring 56. As described above, in the fuel injection valve of the present embodiment, the movement direction of the first piston 53 and the movement direction of the second piston 54 due to the contraction of the piezo element stack 4 are reversed.

  Then, by the movement of the discharge valve 32, the discharge valve 32 comes into contact with the storage chamber side sheet surface 311 and the discharge passage 315 is closed.

  According to this embodiment, the same effect as that of the first embodiment can be obtained.

(Third embodiment)
A third embodiment of the present invention will be described. In this embodiment, the configuration of the displacement transmission mechanism 5 is partly changed, and the other parts are the same as those in the first embodiment. Therefore, only the parts different from the first embodiment will be described.

  As shown in FIG. 6, in the first cylinder 51, a first cylinder hole 511 and a second piston large-diameter portion 541 in a cylindrical space into which the first piston 53 is slidably inserted are slidably inserted. A third cylinder hole 512 in a cylindrical space to be formed, and a second oil-tight chamber 572 filled with fuel that is located on the second cylinder 52 side with respect to the third cylinder hole 512 are formed.

  The first cylinder hole 511 has an opening on the piezoelectric element laminate 4 side. In the first cylinder hole 511, a space between the bottom inner wall surface of the first cylinder 51 and the first piston end surface 534 is a first oil-tight chamber 571 filled with fuel.

  The first oil-tight chamber 571 and the second oil-tight chamber 572 are communicated with each other through an oil-tight chamber communication hole 513 formed in the first cylinder 51. Note that the first oil-tight chamber 571 and the second oil-tight chamber 572 constitute the oil-tight chamber of the present invention.

  The third cylinder hole 512 has an opening on the second cylinder 52 side. A part of the third cylinder hole 512 is a sliding part in which the second piston large diameter part 541 slides, and the remaining part of the first piston hole 531 is in the spring chamber 514 in which the piston spring 56 is disposed. It has become. The spring chamber 514 communicates with the storage chamber 13 through a communication hole 515 formed in the first cylinder 51.

  The second piston 54 includes a protrusion 546 that extends from the end surface of the second piston large-diameter portion 541 toward the bottom of the spring chamber 514. When the protrusion 546 contacts the bottom of the spring chamber 514, the lift amount of the second piston 54 is defined.

  In the above configuration, when the piezoelectric element laminate 4 is charged when the needle valve is closed as shown in FIG. 6, that is, when the discharge valve 32 is in contact with the storage chamber side seat surface 311, the piezoelectric element laminate 4 is charged. The body 4 extends. Accordingly, the first piston 53 is driven in a direction away from the piezo element stack 4, and the pressure in the first oil-tight chamber 571 and the second oil-tight chamber 572 is increased by the first piston 53.

  Further, the pressure in the second oil tight chamber 572 that has been increased in pressure acts on the second piston step surface 543, and the second piston 54 and the discharge valve 32 are driven toward the piezoelectric element laminate 4 side. That is, the direction of movement of the first piston 53 and the direction of movement of the second piston 54 associated with the extension of the piezoelectric element stack 4 are reversed, and the discharge valve 32 is disposed on the storage chamber side seat surface as the piezoelectric element stack 4 extends. Driven away from 311.

  The movement of the discharge valve 32 causes the discharge valve 32 to move away from the storage chamber side seat surface 311 and the discharge passage 315 is opened.

  On the other hand, when the charge of the piezoelectric element laminate 4 is discharged in the needle open state, that is, when the discharge valve 32 is away from the storage chamber side seat surface 311, the piezoelectric element laminate 4 contracts. Accordingly, the first piston 53 urged by the piezo spring 55 follows the piezo element laminate 4 and moves toward the piezo element laminate 4, and the first oil-tight chamber 571 and the second oil-tight chamber 572 are moved. The pressure drops.

  Therefore, the second piston 54 and the discharge valve 32 move toward the intermediate body 31 by the urging force of the piston spring 56. As described above, in the fuel injection valve of the present embodiment, the movement direction of the first piston 53 and the movement direction of the second piston 54 due to the contraction of the piezo element stack 4 are reversed.

  Then, by the movement of the discharge valve 32, the discharge valve 32 comes into contact with the storage chamber side sheet surface 311 and the discharge passage 315 is closed.

  According to this embodiment, the same effect as that of the first embodiment can be obtained.

  Further, since the protrusion 546 abuts against the bottom of the spring chamber 514, the lift amount of the second piston 54 is defined, so the time from when the discharge valve 32 closes the discharge passage 315 to when the discharge passage 315 is opened. That is, the variation in the valve closing response time can be reduced.

  Furthermore, since the first piston 53 does not include the first piston hole 531 (see FIG. 2), the processing is easy.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. In this embodiment, the configuration of the displacement transmission mechanism 5 is partly changed, and the other parts are the same as those in the first embodiment. Therefore, only the parts different from the first embodiment will be described.

  As shown in FIG. 7, the first piston 53 and the second piston large diameter portion 541 of the second piston 54 are slidably inserted into the first cylinder hole 511 of the first cylinder 51. An oil-tight chamber 57 is formed between the first piston 53 and the second piston large-diameter portion 541, and a piston spring 56 is disposed in the oil-tight chamber 57.

  Of the space of the first cylinder hole 511, the space closer to the second cylinder 52 than the second piston large diameter portion 541 is communicated with the storage chamber 13 through a communication hole 516 formed in the first cylinder 51.

  In the second cylinder 52, a second cylinder through-hole 522 that is a cylindrical space having a diameter larger than that of the second piston small-diameter portion 542 is formed. The distal end side of the second piston small diameter portion 542 is located in the second cylinder through hole 522, and the discharge valve 32 is attached to the distal end portion of the second piston small diameter portion 542.

  In the above configuration, in the present embodiment, the needle valve closed state shown in FIG. 7, that is, the state where the discharge valve 32 is in contact with the storage chamber side seat surface 311 is held in a state where the piezoelectric element laminate 4 is extended. .

  And if the electric charge of the piezoelectric element laminated body 4 is discharged from this state, the piezoelectric element laminated body 4 will shrink | contract. Accordingly, the first piston 53 urged by the piezo spring 55 follows the piezo element laminate 4 and moves toward the piezo element laminate 4 so that the pressure in the oil-tight chamber 57 decreases.

  Due to the pressure drop in the oil tight chamber 57, the second piston 54 and the discharge valve 32 move toward the piezoelectric element laminate 4 side, the discharge valve 32 moves away from the storage chamber side seat surface 311 and the discharge passage 315 is opened.

  When the discharge passage 315 is opened, the fuel in the discharge passage 315 flows out into the storage chamber 13 through the communication hole 516 and the second cylinder through hole 522, the nozzle needle 2 moves in the valve opening direction, and the injection hole 211 Is opened and fuel is injected.

  On the other hand, when the piezo element laminate 4 is charged in the needle open state, that is, when the discharge valve 32 is away from the storage chamber side seat surface 311, the piezo element laminate 4 expands. Accordingly, the first piston 53 is driven in a direction away from the piezo element stack 4, and the pressure in the oil-tight chamber 57 is increased by the first piston 53.

  The increased pressure in the oil tight chamber 57 acts on the second piston large diameter portion 541, the second piston 54 and the discharge valve 32 move toward the intermediate body 31, and the discharge valve 32 moves to the storage chamber side seat surface. 311 is contacted.

  When the discharge passage 315 is closed, the outflow of fuel in the discharge passage 315 stops, the nozzle needle 2 moves in the valve closing direction, the nozzle hole 211 is closed, and fuel injection ends.

  According to the present embodiment, the discharge valve 32 is driven to a position where the discharge valve 32 comes into contact with the storage chamber side sheet surface 311 as the piezoelectric element stack 4 is extended by charging of the electric charge. be able to.

  Accordingly, there is no need to dispose the rod portion, which is part of the means for transmitting the expansion and contraction of the piezoelectric element laminate 4 to the discharge valve 32 as in the conventional case, in the discharge passage 315, and the cross-sectional area of the discharge passage 315 is reduced. Can do.

  As a result, the pressure receiving area of the discharge valve 32 can be reduced, and the discharge valve 32 can be driven with small energy.

  In this embodiment, the displacement transmission mechanism 5 may be eliminated, and the discharge valve 32 may be directly driven by the piezoelectric element laminate 4.

(Other embodiments)
In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably.

  Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible.

  In each of the above-described embodiments, it is needless to say that elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Yes.

  Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case.

  Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the component, etc., the shape, unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to the positional relationship or the like.

4 Piezoelectric stack 5 Displacement transmission mechanism (transmission means)
DESCRIPTION OF SYMBOLS 13 Accommodating chamber 21 Nozzle body 22 Nozzle needle 24 Nozzle cylinder 26 Control chamber 31 Intermediate body 32 Discharge valve 33 Control plate 53 1st piston 54 2nd piston 57 Oiltight chamber 211 Injection hole 311 Accommodating chamber side seat surface 312 Control chamber side seat surface 314 High pressure supply passage 315 Discharge passage

Claims (6)

A piezoelectric element laminate (4) disposed in the low-pressure storage chamber (13) and extending and contracting by charge and discharge;
A transmission means (5) disposed in the storage chamber and having an oil-tight chamber (57) filled with fuel to transmit expansion and contraction of the piezoelectric element laminate;
A nozzle body (21) having an injection hole (211) for injecting high pressure fuel into the combustion chamber of the internal combustion engine;
A nozzle needle (22) that reciprocates in the nozzle body and opens and closes the nozzle hole at one end;
A nozzle cylinder (24) having a control chamber (26) in which the other end side of the nozzle needle is slidably inserted and a fuel pressure is applied to the nozzle needle in a valve closing direction;
A storage chamber side sheet surface (311) exposed in the storage chamber, a control chamber side sheet surface (312) exposed in the control chamber, a discharge passage (315) for discharging fuel from the control chamber to the storage chamber, and An intermediate body (31) having a high pressure supply passage (314) for supplying high pressure fuel to the control chamber;
A control plate (33) disposed in the control chamber, reciprocally displaced, and opening and closing the high-pressure supply passage by contacting and separating from the control chamber side seat surface;
A discharge valve (32) disposed in the storage chamber and driven by the transmission means to open and close the discharge passage by contacting and separating from the storage chamber side seat surface;
The transmission means is driven by the piezo element stack, and a first piston (53) that raises the pressure of the oil tight chamber as the piezo element stack is extended by charge charging, and a pressure of the oil tight chamber. A second piston (54) that receives and operates to drive the discharge valve, and further, the moving direction of the first piston and the moving direction of the second piston are opposite to each other, and the piezoelectric element laminate body The fuel injection valve is configured so that the discharge valve is driven in a direction away from the storage chamber side seat surface as the length of the fuel cell extends. The second piston includes a second piston large diameter portion (541) having a smaller diameter than the first piston, a second piston small diameter portion (542) having a smaller diameter than the second piston large diameter portion, and the second piston. A second piston step surface (543) formed at a boundary portion between the large diameter portion and the second piston small diameter portion and receiving the pressure of the oil tight chamber;
The first piston includes a first piston hole (531) into which the second piston large diameter portion is slidably inserted.
The transmission means includes a first cylinder hole (511) into which the first piston is slidably inserted, and a second cylinder hole (521) into which the second piston small diameter portion is slidably inserted. The fuel injection valve according to claim 1, further comprising a cylinder (51, 52). The second piston includes a second piston large-diameter portion (541), a second piston small-diameter portion (542) having a smaller diameter than the second piston large-diameter portion, the second piston large-diameter portion, and the second piston. A second piston step surface (543) that is formed at the boundary with the small diameter portion and receives the pressure of the oil tight chamber, and is formed inside the second piston large diameter portion and the first piston is slidably inserted. A second piston hole (544),
The transmission means includes a first cylinder hole (511) into which the second piston large diameter portion is slidably inserted, and a second cylinder hole (521) into which the second piston small diameter portion is slidably inserted. Comprising a cylinder (51, 52) formed with
The oil tight chamber includes a first oil tight chamber (571) that is a part of the second piston hole, and a second oil tight chamber (572) that is a part of the first cylinder hole,
2. The fuel injection valve according to claim 1, wherein the second piston includes an oil tight chamber communication hole (545) for communicating the first oil tight chamber with the second oil tight chamber. The second piston includes a second piston large-diameter portion (541), a second piston small-diameter portion (542) having a smaller diameter than the second piston large-diameter portion, the second piston large-diameter portion, and the second piston. A second piston step surface (543) that is formed at the boundary with the small diameter portion and receives the pressure of the oil tight chamber,
The transmission means includes a first cylinder hole (511) into which the first piston is slidably inserted, a second cylinder hole (521) into which the second piston small diameter portion is slidably inserted, and the first cylinder hole (521). A cylinder (51, 52) having a third cylinder hole (512) into which a two-piston large-diameter portion is slidably inserted;
The oil tight chamber is formed between the first oil tight chamber (571) which is a part of the first cylinder hole, the second cylinder hole and the third cylinder hole and on the outer peripheral side of the second piston. A second oil-tight chamber (572) from which the second piston step surface is exposed,
2. The fuel injection valve according to claim 1, wherein the cylinder includes an oil-tight chamber communication hole (513) that allows the first oil-tight chamber and the second oil-tight chamber to communicate with each other. A piezoelectric element laminate (4) disposed in the low-pressure storage chamber (13) and extending and contracting by charge and discharge;
A nozzle body (21) having an injection hole (211) for injecting high pressure fuel into the combustion chamber of the internal combustion engine;
A nozzle needle (22) that reciprocates in the nozzle body and opens and closes the nozzle hole at one end;
A nozzle cylinder (24) having a control chamber (26) in which the other end side of the nozzle needle is slidably inserted and a fuel pressure is applied to the nozzle needle in a valve closing direction;
A storage chamber side sheet surface (311) exposed in the storage chamber, a control chamber side sheet surface (312) exposed in the control chamber, a discharge passage (315) for discharging fuel from the control chamber to the storage chamber, and An intermediate body (31) having a high pressure supply passage (314) for supplying high pressure fuel to the control chamber;
A control plate (33) disposed in the control chamber, reciprocally displaced, and opening and closing the high-pressure supply passage by contacting and separating from the control chamber side seat surface;
A discharge valve (32) that is disposed in the storage chamber and opens and closes the discharge passage by coming into contact with and separating from the storage chamber side sheet surface as the piezoelectric element laminate expands and contracts.
A fuel injection valve configured to be driven to a position where the discharge valve abuts against the storage chamber side seat surface when the piezoelectric element laminate is extended by charging of electric charge.   6. A transmission means (5) disposed in the storage chamber and having an oil-tight chamber (57) filled with fuel and transmitting expansion and contraction of the piezoelectric element laminate to the discharge valve. The fuel injection valve described in 1.

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