JP6547660B2 - Fuel injection valve - Google Patents

Description

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

  Conventionally, as a fuel injection valve of this type, 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 the injection hole, and the nozzle needle is biased in the closing direction by the fuel pressure of the control chamber. Then, by discharging the fuel in the control chamber to the low pressure portion, the nozzle needle is operated in the valve opening direction to start fuel injection, and the high pressure fuel is flowed into the control chamber to operate the nozzle needle in the valve closing direction. And end fuel injection.

  In addition, by installing two solenoid valves that open and close the path that discharges the fuel in the control chamber to the low pressure part and operating the solenoid valves independently, the discharge speed of the fuel flowing out from the control chamber can be two stages. I'm trying to switch. Thus, the valve opening speed of the nozzle needle is switched to switch the injection rate characteristic at the initial stage of injection.

US Patent Application Publication No. 2013/0233941

  However, the conventional fuel injection valve has a problem that the size of the fuel injection valve is increased because two solenoid valves are used to switch the discharge speed of the fuel flowing out of the control chamber in two steps.

  SUMMARY OF THE INVENTION In view of the above-described points, the present invention has an object to miniaturize a fuel injection valve that switches the discharge speed of fuel flowing out of a control chamber in two steps.

  In order to achieve the above object, according to the invention as set forth in claim 1, a nozzle body (21) having injection holes (211) for injecting high pressure fuel into a combustion chamber of an internal combustion engine, and reciprocating injection within the nozzle body A nozzle needle (22) for opening and closing the hole, a control chamber (26, 912) for applying fuel pressure in the valve closing direction to the nozzle needle, and a discharge passage (315) for discharging the fuel in the control chamber to the low pressure portion (12) , A high pressure supply passage (322) for supplying high pressure fuel to the control chamber, a first valve body (33) for opening and closing between the control chamber and the discharge passage, and opening and closing between the control chamber and the high pressure supply passage A second valve body (36), a piezoelectric actuator (4) that expands and contracts due to charge and discharge of electric charge, and drives the first valve body and the second valve body; And the first drive voltage And a drive voltage application device (7) for switching to a second drive voltage having a high voltage, and when the drive voltage is not applied to the piezo actuator, the first valve body closes between the control chamber and the discharge passage. When the first drive voltage is applied to the actuator, only the first valve body of the first and second valve bodies is driven to open the space between the control chamber and the discharge passage, and the piezoelectric actuator is When the drive voltage is applied, the first valve body is driven to open the space between the control chamber and the discharge passage, and the second valve body is driven to open the space between the control chamber and the high pressure supply passage.

  According to this, since the discharge speed of the fuel flowing out of the control chamber can be switched in two steps by one piezo actuator, the fuel injection valve can be miniaturized.

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

It is a sectional view showing a fuel injection valve concerning a 1st embodiment of the present invention. It is an expanded sectional view of an important section of a fuel injection valve concerning a 1st embodiment. It is an expanded sectional view of an important section showing other operation states of a fuel injection valve concerning a 1st embodiment. It is a time chart which is provided to the operation explanation of the fuel injection valve concerning a 1st embodiment. It is sectional drawing which shows the principal part of the fuel injection valve which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the principal part of the fuel injection valve which concerns on 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to the items described in the preceding embodiments may be denoted by the same reference numerals, and the description thereof may be omitted. In addition, in each embodiment, when only a part of the components is described, the components described in the preceding embodiments can be applied to other parts of the components.

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

  In the fuel injection valve of the present embodiment shown in FIGS. 1 to 3, high pressure fuel supplied from a common rail (not shown) is used as a combustion chamber of a compression ignition type internal combustion engine (hereinafter referred to as internal combustion engine; not shown). It is something to inject.

  The fuel injection valve includes an injector body 1, a nozzle 2, a control valve mechanism 3, a piezo actuator 4, a displacement transfer mechanism 5, a retaining nut 6, and a drive voltage application device 7 as main components.

  The substantially cylindrical injector body 1 is formed with a high pressure fuel passage 11 through which high pressure fuel supplied from the common rail flows, and a storage chamber 12 in which the piezoelectric actuator 4 and the displacement transmission mechanism 5 are stored. The storage chamber 12 is connected to a fuel tank (not shown) and is always at low pressure. In addition, the storage chamber 12 corresponds to the low pressure part of this invention.

  The nozzle 2 has a substantially bottomed cylindrical nozzle body 21, a substantially cylindrical nozzle needle 22 slidably inserted in the nozzle body 21, a nozzle spring 23 for urging the nozzle needle 22 in a valve closing direction, and a cylindrical shape. A needle cylinder 24 is provided.

  The nozzle body 21 is provided with an injection hole 211 for ejecting high pressure fuel to a combustion chamber of an internal combustion engine, and the tip end portion (that is, the injection hole side end) of the nozzle needle 22 contacts and separates from the nozzle body 21. Is to be opened and closed.

  A fuel reservoir chamber 25 is formed in the nozzle body 21 as a high pressure portion to which high pressure fuel is constantly supplied from the common rail, and high pressure fuel from the common rail flows toward the injection hole 211 via the fuel reservoir chamber 25. ing.

  The needle cylinder 24 is pressed by a nozzle spring 23 against a second intermediate body 32 described later, and the rear end (that is, the end on the non-injection hole side) of the nozzle needle 22 is inserted into the needle cylinder 24.

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

  The control valve mechanism 3 for controlling the pressure in the control chamber 26 includes a first intermediate body 31, a second intermediate body 32, a first valve body 33, a first valve body spring 34, a first rod 35, a second valve body 36, A second valve body spring 37 and a second rod 38 are provided.

  Then, by sandwiching the first intermediate body 31 and the second intermediate body 32 between the injector body 1 and the nozzle 2 and screwing the injector body 1 and the retaining nut 6, the components of the fuel injection valve can be obtained. It is integrated.

  The first intermediate body 31 and the second intermediate body 32 are stacked, the first intermediate body 31 abuts on the injector body 1, and the second intermediate body 32 abuts on the nozzle body 21.

  The first intermediate body 31 and the second intermediate body 32 are formed with high pressure fuel passages 311 and 321 for communicating the high pressure fuel passage 11 of the injector body 1 with the fuel reservoir 25 in the nozzle body 21.

  A first valve chamber 312 is formed in the first intermediate body 31 and extends from the end face of the second intermediate body 32 toward the storage chamber 12. The first valve body 33 and the first valve body spring 34 are disposed in the first valve chamber 312.

  At the bottom of the first valve chamber 312, a tapered low-pressure seat surface 313 to which the first valve body 33 contacts and separates is formed. The first valve body 33 is biased toward the low pressure seat surface 313 by the first valve spring 34.

  A first rod insertion hole 314 is formed in the first intermediate body 31. The first rod insertion hole 314 is open at one end on the end of the low pressure seat surface 313 on the storage chamber 12 side to connect the first valve chamber 312 and the storage chamber 12. ing. The first rod 35 is slidably inserted into the first rod insertion hole 314.

  The first intermediate body 31 is formed with a discharge passage 315 which is open at one end to the low pressure seat surface 313 and which causes the first valve chamber 312 and the storage chamber 12 to communicate with each other. Then, the first valve body 33 is brought into contact with and separated from the low pressure seat surface 313, whereby the space between the discharge passage 315 and the first valve chamber 312 is opened and closed.

  In the second intermediate body 32, a high pressure supply passage 322 is formed, which connects the high pressure fuel passage 321 and the control chamber 26 and supplies high pressure fuel to the control chamber 26.

  The second intermediate body 32 is formed with a second rod insertion hole 323 communicating the first valve chamber 312 with the control chamber 26. The second rod 38 is slidably inserted into the second rod insertion hole 323. A rod through hole 381 and a rod groove 382 are formed in the second rod 38, and the first valve chamber 312 and the control chamber 26 are always in communication via the rod through hole 381 and the rod groove 382. The rod through hole 381 and the rod groove 382 constitute a communication passage of the present invention.

  In the second intermediate body 32, a flat high-pressure sheet surface 324 is formed around the opening on the control chamber 26 side in the high-pressure supply passage 322.

  The second valve body 36 and the second valve body spring 37 are disposed in the control chamber 26. Then, the disc-like second valve body 36 comes into contact with and separates from the high pressure seat surface 324, so that the space between the high pressure supply passage 322 and the control chamber 26 is opened and closed. The second valve spring 37 biases the second valve body 36 toward the high pressure seat surface 324.

  An orifice 361 penetrating in the axial direction of the second valve body 36 is formed at a radial center of the second valve body 36. When the second valve body 36 is in contact with the high pressure seat surface 324, the orifice 361 and the rod through hole 381 communicate with each other.

  The piezo actuator 4 is configured of a cylindrical piezo element laminate that is formed by laminating a large number of piezo elements and expanding and contracting by charge and discharge of electric charge. Then, the piezo actuator 4, the first valve body 33 and the second valve body 36 are arranged in series, and the first valve body 33 and the second valve body 36 are driven as the piezoelectric actuator 4 expands and contracts. ing.

  The drive voltage application device 7 switches the drive voltage applied to the piezo actuator 4 to a first drive voltage and a second drive voltage higher than the first drive voltage.

  The length in the stacking direction of the piezoelectric actuator 4 is shortest when no drive voltage is applied, and is longer when the second drive voltage is applied than when the first drive voltage is applied. Become.

  The displacement transfer mechanism 5 includes a piston cylinder 51 and two pistons 52 and 53 slidably inserted in the piston cylinder 51. A fluid chamber 54 filled with fuel is formed between the two pistons 52 and 53.

  The first piston 52 is directly driven by the piezo actuator 4. When the piezoelectric actuator 4 is expanded, the pressure of the liquid chamber 54 is increased by the first piston 52.

  The second piston 53 is smaller in diameter than the first piston 52 and operates by receiving the pressure of the liquid chamber 54, and the displacement of the second piston 53 is transmitted to the first valve body 33 via the first rod 35. It is supposed to be.

  When the piezoelectric actuator 4 is extended, the piezoelectric valve 4 is driven to move the first valve body 33 away from the low pressure seat surface 313. At this time, the change in length of the piezoelectric actuator 4 is expanded by the pressure receiving area ratio of the first piston 52 and the second piston 53 and transmitted to the first valve body 33.

  Next, the operation of the fuel injection valve will be described based on FIGS. 1 to 4. In FIG. 4, the solid line indicates the characteristic when the first drive voltage is applied to the piezo actuator 4, and the dashed-dotted line indicates the characteristic when the second drive voltage is applied to the piezo actuator 4.

  First, when the first drive voltage is applied from the drive voltage application device 7 to the piezo actuator 4 to charge the piezo actuator 4 when the needle is in the valve closed state (that is, the injection hole 211 is closed), piezo The actuator 4 is extended to be in the state shown in FIG.

  That is, the piezoelectric actuator 4 is extended to drive the first piston 52, and the pressure of the liquid chamber 54 is increased by the first piston 52. The second piston 53 is driven toward the first valve body 33 by the increased pressure of the liquid chamber 54.

  Further, the displacement of the second piston 53 is transmitted to the first valve body 33 via the first rod 35, so that the first valve body 33 resists the biasing force of the first valve body spring 34, and the low pressure sheet It is driven away from the surface 313.

  Then, due to the movement of the first valve body 33, the first valve body 33 is separated from the low pressure seat surface 313, and the space between the discharge passage 315 and the first valve chamber 312 is opened. In other words, since the first valve chamber 312 and the control chamber 26 are always in communication via the orifice 361 of the second valve body 36, the rod through hole 381 and the rod groove 382, the low pressure of the first valve body 33 By leaving the seat surface 313, the space between the discharge passage 315 and the control chamber 26 is opened.

  Further, the first valve body 33 is stopped when it abuts on the second rod 38, and the state in which the second valve body 36 abuts on the high pressure seat surface 324 is maintained, and the high pressure supply passage 322 and the control chamber 26 Remains closed during the In other words, when the first drive voltage is applied, only the first valve body 33 of the first valve body 33 and the second valve body 36 is driven along with the extension of the piezoelectric actuator 4.

  Therefore, the fuel in the control chamber 26 flows out to the low pressure storage chamber 12 through the orifice 361 of the second valve body 36, the rod through hole 381, the rod groove 382, the first valve chamber 312 and the discharge passage 315.

  As a result, the pressure in the control chamber 26 decreases and the force for urging the nozzle needle 22 in the valve closing direction decreases, so the nozzle needle 22 moves in the valve opening direction, and fuel is injected from the injection hole 211 into the combustion chamber of the internal combustion engine. Is injected.

  Next, when the first drive voltage is applied to the piezo actuator 4 and the needle valve is opened (that is, the injection hole 211 is opened), the application of the drive voltage from the drive voltage application device 7 to the piezo actuator 4 is stopped Then, when the electric charge of the piezoelectric actuator 4 is discharged, the piezoelectric actuator 4 contracts and the pressure of the liquid chamber 54 decreases, so the first valve body 33, the first rod 35, and the second piston 53 become the first valve. The body spring 34 pushes back.

  By the movement of the first valve body 33, the first valve body 33 abuts on the low pressure seat surface 313 and the space between the discharge passage 315 and the first valve chamber 312 is closed. In other words, when the first valve body 33 abuts on the low pressure seat surface 313, the space between the discharge passage 315 and the control chamber 26 is closed.

  Here, at a time before the space between the discharge passage 315 and the first valve chamber 312 is closed, a pressure difference is generated before and after the orifice 361 of the second valve body 36, and the pressure in the control chamber 26 is the first It is higher than the pressure of the valve chamber 312.

  Then, when the space between the discharge passage 315 and the first valve chamber 312 is closed as described above, the fuel in the control chamber 26 flows to the first valve chamber 312 through the orifice 361 and the rod through hole 381, and The pressure difference between the valve chamber 312 and the control chamber 26 is reduced.

  Since the reduction of the pressure difference in the control chamber 26 reduces the force for urging the second valve body 36 toward the high pressure seat surface 324, the second valve body 36 is driven by the pressure of the high pressure fuel in the high pressure supply passage 322. , Is driven away from the high pressure sheet surface 324.

  Then, by the movement of the second valve body 36, the second valve body 36 is separated from the high pressure seat surface 324 and the space between the high pressure supply passage 322 and the control chamber 26 is opened. Fuel flows in. As a result, the pressure in the control chamber 26 increases and the force to urge the nozzle needle 22 in the valve closing direction increases, so the nozzle needle 22 moves in the valve closing direction, the injection hole 211 is closed, and the fuel injection ends. Do.

  Next, when the second drive voltage is applied from the drive voltage application device 7 to the piezo actuator 4 and the piezo actuator 4 is charged while the needle is in the valve closed state, the piezo actuator 4 is expanded, as shown in FIG. It will be in the state shown.

  That is, the length of the piezoelectric actuator 4 when the second drive voltage is applied is longer than when the first drive voltage is applied. Therefore, the amount of movement (that is, the amount of lift) of the first valve body 33 when the second drive voltage is applied to the piezo actuator 4 is the first valve body when the first drive voltage is applied to the piezo actuator 4 It becomes larger than the movement amount of 33 (see FIG. 4).

  Thus, with the expansion of the piezoelectric actuator 4, the first valve body 33 is first driven in the direction away from the low pressure seat surface 313, and then the second valve body 36 via the first valve body 33 and the second rod 38. Is driven away from the high pressure sheet surface 324 to open the space between the high pressure supply passage 322 and the control chamber 26.

  Therefore, the fuel in the control chamber 26 flows out to the low pressure storage chamber 12 through the orifice 361 of the second valve body 36, the rod through hole 381, the rod groove 382, the first valve chamber 312 and the discharge passage 315. The high pressure fuel flows from the high pressure supply passage 322 into the control chamber 26.

  Then, since the amount of fuel outflow from the control chamber 26 is set to be larger than the amount of inflow of high pressure fuel into the control chamber 26, the pressure in the control chamber 26 is lowered and the nozzle needle 22 is opened. The fuel is moved and injected from the injection hole 211 into the combustion chamber of the internal combustion engine.

  Next, when the second drive voltage is applied to the piezo actuator 4 and the needle valve is open, the application of the drive voltage from the drive voltage application device 7 to the piezo actuator 4 is stopped to discharge the charge of the piezo actuator 4 The second valve body 36, the second rod 38, the first valve body 33, the first rod 35, and the second piston 53 are the first valve, because the piezoelectric actuator 4 contracts and the pressure in the liquid chamber 54 decreases. The valve body spring 34 and the second valve body spring 37 push back.

  By the movement of the second valve body 36, the second valve body 36 abuts on the high pressure seat surface 324 and the space between the high pressure supply passage 322 and the control chamber 26 is closed (that is, the state of FIG. 2).

  Hereinafter, when the first drive voltage is applied to the piezo actuator 4 and the needle is in the valve open state, the operation is the same as when the application of the drive voltage to the piezo actuator 4 is stopped, and fuel injection ends .

  Here, when the first drive voltage is applied to the piezo actuator 4, the fuel in the control chamber 26 only flows out to the storage chamber 12. On the other hand, when the second drive voltage is applied to the piezo actuator 4, the fuel of the control chamber 26 flows out to the storage chamber 12, and the high pressure fuel flows from the high pressure supply passage 322 into the control chamber 26.

  Therefore, when the first drive voltage is applied to the piezo actuator 4, the fuel flow rate out of the control chamber 26 is higher than when the second drive voltage is applied to the piezo actuator 4. That is, the discharge speed of the fuel flowing out of the control chamber 26 can be switched in two steps by one piezoelectric actuator 4, and in turn, the lift speed of the nozzle needle 22 (that is, the valve opening speed) is switched in two steps. be able to.

  Then, as shown in FIG. 4, when the first drive voltage is applied to the piezo actuator 4, the pressure drop in the control chamber 26 is faster than when the second drive voltage is applied to the piezo actuator 4. Since the lift speed of the nozzle needle 22 is high, the injection rate at the initial stage of injection rapidly increases.

  As described above, according to the present embodiment, since the discharge speed of the fuel flowing out of the control chamber 26 can be switched in two steps by one piezo actuator 4, the fuel injection valve can be miniaturized. Can.

Second Embodiment
The second embodiment will be described with reference to FIG. In the present embodiment, the description of the same or equivalent parts as in the first embodiment will be omitted or simplified.

  As shown in FIG. 5, an intermediate chamber 81 communicating with the control chamber 26 via the second rod insertion hole 323 is formed in the second intermediate body 32.

  A third intermediate body 82 is sandwiched between the first intermediate body 31 and the second intermediate body 32. The third intermediate body 82 is formed with an intermediate pin insertion hole 821 that allows the intermediate chamber 81 and the first valve chamber 312 to communicate with each other. Further, in the third intermediate body 82, a high pressure fuel passage 822 is formed, which connects the high pressure fuel passage 311 of the first intermediate body 31 and the high pressure fuel passage 321 of the second intermediate body 32 with each other.

  In the first valve chamber 312, the intermediate chamber 81 and the intermediate pin insertion hole 821, an intermediate pin 83 is disposed as a displacement transmitting member for transmitting the displacement of the first valve body 33 to the second valve body 36 when the piezoelectric actuator 4 is extended. It is done. The intermediate pin 83 includes a flange portion 831 located in the intermediate chamber 81, and a pin portion 832 slidably inserted into the intermediate pin insertion hole 821 and having a leading end entering the first valve chamber 312. . Further, in the intermediate pin 83, an intermediate pin through hole 833 and an intermediate pin groove 834 are formed as a communication passage that causes the intermediate chamber 81 and the first valve chamber 312 to communicate with each other.

  In the intermediate chamber 81, an intermediate spring 84 is disposed which biases the intermediate pin 83 toward the first valve body 33 with a predetermined set load. More specifically, the intermediate spring 84 biases the intermediate pin 83 in a direction in which the first valve body 33 closes between the first valve chamber 312 and the discharge passage 315.

  Next, the operation of the fuel injection valve will be described. Hereinafter, a force for driving the first valve body 33 via the displacement transfer mechanism 5 when the first drive voltage is applied to the piezoelectric actuator 4 will be referred to as a first drive force. Further, when a second drive voltage is applied to the piezo actuator 4, a force for driving the first valve body 33 via the displacement transfer mechanism 5 is hereinafter referred to as a second drive force.

  First, when the first drive voltage is applied from the drive voltage application device 7 to the piezo actuator 4 in the needle closed state, the first valve body 33 is driven against the biasing force of the first valve body spring 34 Thus, the space between the discharge passage 315 and the first valve chamber 312 is opened.

  When the first valve body 33 abuts on the intermediate pin 83, the intermediate spring 84 opposes the driving force of the piezo actuator 4. Here, the sum of the biasing force of the first valve body spring 34 and the set load of the intermediate spring 84 when the first valve body 33 abuts against the intermediate pin 83 is larger than the first driving force, and the second It is set smaller than the driving force. Therefore, when the first valve body 33 abuts on the intermediate pin 83, the first valve body 33 reliably stops, and the state in which the second valve body 36 abuts on the high pressure seat surface 324 is reliably maintained.

  Thus, when the first valve body 33 is in contact with the intermediate pin 83, the fuel in the control chamber 26 is the orifice 361 of the second valve body 36, the rod through hole 381, the intermediate pin through hole 833, and the intermediate pin groove The fluid flows into the low pressure storage chamber 12 via the first valve chamber 312 and the discharge passage 315.

  As a result, the pressure in the control chamber 26 decreases and the force for urging the nozzle needle 22 in the valve closing direction decreases, so the nozzle needle 22 moves in the valve opening direction, and fuel is injected from the injection hole 211 into the combustion chamber of the internal combustion engine. Is injected.

  Next, when the first drive voltage is applied to the piezo actuator 4 and the needle valve is open, the application of the drive voltage from the drive voltage application device 7 to the piezo actuator 4 is stopped to discharge the charge of the piezo actuator 4 The first valve body 33 is pushed back by the first valve body spring 34.

  By the movement of the first valve body 33, the first valve body 33 abuts on the low pressure seat surface 313 and the space between the discharge passage 315 and the first valve chamber 312 is closed. Thereafter, the fuel injection is finished by operating in the same manner as in the first embodiment.

  Next, when the second drive voltage is applied from the drive voltage application device 7 to the piezo actuator 4 in the needle closed state, the first valve body 33 resists the biasing force of the first valve body spring 34. By being driven, the space between the discharge passage 315 and the first valve chamber 312 is opened.

  As described above, the sum of the biasing force of the first valve body spring 34 and the set load of the intermediate spring 84 when the first valve body 33 abuts against the intermediate pin 83 is set smaller than the second driving force. ing.

  Therefore, after the first valve body 33 abuts on the intermediate pin 83, the first valve body 33 and the intermediate pin 83 are driven against the first valve body spring 34 and the intermediate spring 84. Then, when the intermediate pin 83 abuts on the second rod 38, the second valve body 36 is driven away from the high pressure seat surface 324 via the second rod 38, and the high pressure supply passage 322 and the control chamber 26 An interval is opened.

  As a result, the fuel in the control chamber 26 flows out to the low pressure storage chamber 12 through the orifice 361 of the second valve body 36 and the high pressure fuel flows from the high pressure supply passage 322 into the control chamber 26.

  Then, since the amount of fuel outflow from the control chamber 26 is set to be larger than the amount of inflow of high pressure fuel into the control chamber 26, the pressure in the control chamber 26 is lowered and the nozzle needle 22 is opened. The fuel is moved and injected from the injection hole 211 into the combustion chamber of the internal combustion engine.

  Next, when the second drive voltage is applied to the piezo actuator 4 and the needle valve is open, the application of the drive voltage from the drive voltage application device 7 to the piezo actuator 4 is stopped to discharge the charge of the piezo actuator 4 The first valve body 33 is pushed back by the first valve body spring 34, the intermediate pin 83 is pushed back by the intermediate spring 84, and the second rod 38 and the second valve body 36 are pushed back by the second valve body spring 37.

  By the movement of the second valve body 36, the second valve body 36 abuts on the high pressure seat surface 324 and the space between the second valve body 36 and the high pressure supply passage 322 is closed. Thereafter, the fuel injection is finished by operating in the same manner as in the first embodiment.

  According to this embodiment, the same effect as that of the first embodiment can be obtained. Further, since the intermediate spring 84 is provided, when the first drive voltage is applied to the piezoelectric actuator 4, the state in which the second valve body 36 abuts on the high pressure sheet surface 324 can be reliably maintained.

Third Embodiment
The third embodiment will be described with reference to FIG. In the present embodiment, the description of the same or equivalent parts as in the first embodiment will be omitted or simplified.

  As shown in FIG. 6, a third intermediate body 91 is sandwiched between the nozzle body 21 and the second intermediate body 32. In the third intermediate body 91, an intermediate body control room 912 communicating with the control room 26 via an intermediate body through hole 911 is formed. The intermediate body control chamber 912 is supplied with high pressure fuel via the high pressure supply passage 322. The control room 26 and the intermediate body control room 912 constitute a control room of the present invention.

  The second valve body 36 and the second valve body spring 37 are disposed in the intermediate body control chamber 912. Then, the second valve body 36 is brought into contact with and separated from the high pressure seat surface 324, whereby the space between the high pressure supply passage 322 and the intermediate body control chamber 912 is opened and closed. Further, when the second valve body 36 is in contact with the high pressure seat surface 324, the orifice 361 and the rod through hole 381 communicate with each other.

  The second valve spring 37 is held between the second valve body 36 and the third intermediate body 91 to bias the second valve body 36 toward the high pressure seat surface 324.

  Next, the operation of the fuel injection valve will be described. First, when the first drive voltage is applied from the drive voltage application device 7 to the piezo actuator 4 in the needle closed state, the first valve body 33 is driven against the biasing force of the first valve body spring 34 Thus, the space between the discharge passage 315 and the first valve chamber 312 is opened. In other words, the first valve chamber 312 and the control chamber 26 are always in communication via the intermediate body through hole 911, the intermediate body control chamber 912, the orifice 361 of the second valve body 36, the rod through hole 381 and the rod groove 382. Therefore, when the first valve body 33 separates from the low pressure seat surface 313, the space between the discharge passage 315 and the control chamber 26 is opened.

  Further, the first valve body 33 is stopped when it abuts on the second rod 38, and the state in which the second valve body 36 abuts on the high pressure seat surface 324 is maintained, and the high pressure supply passage 322 and the intermediate body control chamber It remains closed between 912 and 912.

  Therefore, the fuel in the control chamber 26 includes the intermediate body through hole 911, the intermediate body control chamber 912, the orifice 361 of the second valve body 36, the rod through hole 381, the rod groove 382, the first valve chamber 312, and the discharge passage 315. It flows out into the low pressure storage chamber 12 via the low pressure storage chamber 12.

  As a result, the pressure in the control chamber 26 decreases and the force for urging the nozzle needle 22 in the valve closing direction decreases, so the nozzle needle 22 moves in the valve opening direction, and fuel is injected from the injection hole 211 into the combustion chamber of the internal combustion engine. Is injected.

  Next, when the first drive voltage is applied to the piezo actuator 4 and the needle valve is open, the application of the drive voltage from the drive voltage application device 7 to the piezo actuator 4 is stopped to discharge the charge of the piezo actuator 4 The first valve body 33 is pushed back by the first valve body spring 34.

  By the movement of the first valve body 33, the first valve body 33 abuts on the low pressure seat surface 313 and the space between the discharge passage 315 and the first valve chamber 312 is closed.

  Here, at a time before the space between the discharge passage 315 and the first valve chamber 312 is closed, a pressure difference is generated before and after the orifice 361 of the second valve body 36, and the control chamber 26 and the intermediate body control chamber The pressure of 912 is higher than the pressure of the first valve chamber 312.

  Then, as described above, when the space between the discharge passage 315 and the first valve chamber 312 is closed, the fuel in the control chamber 26 and the intermediate body control chamber 912 flows through the orifice 361 and the rod through hole 381. The pressure in the control chamber 26 and the intermediate body control chamber 912 is reduced.

  Since the force of urging the second valve body 36 toward the high pressure seat surface 324 is reduced by the pressure drop of the intermediate body control chamber 912, the second valve body 36 is controlled by the pressure of the high pressure fuel in the high pressure supply passage 322. , Is driven away from the high pressure sheet surface 324.

  Then, by the movement of the second valve body 36, the second valve body 36 is separated from the high pressure seat surface 324 and the space between the second valve body 36 and the high pressure supply passage 322 is opened. To flow. As a result, the pressure in the control chamber 26 and the intermediate body control chamber 912 increases, and the force to urge the nozzle needle 22 in the valve closing direction increases, so the nozzle needle 22 moves in the valve closing direction and the injection hole 211 closes. And the fuel injection ends.

  Next, when the second drive voltage is applied from the drive voltage application device 7 to the piezo actuator 4 in the needle closed state, the first valve body 33 is first driven to move away from the low pressure sheet surface 313 and thereafter The second valve body 36 is driven to move away from the high pressure seat surface 324 via the first valve body 33 and the second rod 38, so that the space between the high pressure supply passage 322 and the intermediate body control chamber 912 is opened.

  Therefore, the fuel in the control chamber 26 includes the intermediate body through hole 911, the intermediate body control chamber 912, the orifice 361 of the second valve body 36, the rod through hole 381, the rod groove 382, the first valve chamber 312, and the discharge passage 315. While flowing out into the low pressure storage chamber 12, the high pressure fuel flows from the high pressure supply passage 322 into the control chamber 26 via the intermediate body control chamber 912.

  Then, since the amount of fuel outflow from the control chamber 26 is set to be larger than the amount of inflow of high pressure fuel into the control chamber 26, the pressure in the control chamber 26 is lowered and the nozzle needle 22 is opened. The fuel is moved and injected from the injection hole 211 into the combustion chamber of the internal combustion engine.

  Next, when the second drive voltage is applied to the piezo actuator 4 and the needle valve is open, the application of the drive voltage from the drive voltage application device 7 to the piezo actuator 4 is stopped to discharge the charge of the piezo actuator 4 The second valve body 36, the second rod 38, the first valve body 33, the first rod 35, and the second piston 53 are the first valve, because the piezoelectric actuator 4 contracts and the pressure in the liquid chamber 54 decreases. The valve body spring 34 and the second valve body spring 37 push back.

  By the movement of the second valve body 36, the second valve body 36 abuts on the high pressure seat surface 324 and the space between the second valve body 36 and the high pressure supply passage 322 is closed. Hereinafter, when the first drive voltage is applied to the piezo actuator 4 and the needle is in the valve open state, the operation is the same as when the application of the drive voltage to the piezo actuator 4 is stopped, and fuel injection ends .

  According to this embodiment, the same effect as that of the first embodiment can be obtained. Further, since the second valve body spring 37 is sandwiched between the second valve body 36 and the third intermediate body 91, the second valve body 36 is not applied with the biasing force of the second valve body spring 37 to the nozzle needle 22. The second valve body spring 37 has a high degree of freedom in design.

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

  Moreover, said each embodiment is not mutually irrelevant and can be combined suitably, unless the combination is clearly impossible.

  Further, in each of the above-described embodiments, it is needless to say that the elements constituting the embodiment are not necessarily essential except when clearly indicated as being essential and when it is considered to be obviously essential in principle. Yes.

  Further, in the above embodiments, when numerical values such as the number, numerical value, amount, range, etc. of constituent elements of the embodiment are mentioned, it is clearly indicated that they are particularly essential and clearly limited to a specific number in principle. It is not limited to the specific number except when it is done.

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

DESCRIPTION OF SYMBOLS 4 piezo actuator 7 drive voltage application device 22 nozzle needle 26 control chamber 33 1st valve body 36 2nd valve body 315 discharge passage 322 high pressure supply passage 912 middle body control chamber

Claims (3)

A nozzle body (21) having injection holes (211) for injecting high pressure fuel into a combustion chamber of an internal combustion engine;
A nozzle needle (22) that reciprocates within the nozzle body to open and close the injection hole;
A control chamber (26, 912) for applying fuel pressure in a valve closing direction to the nozzle needle;
A discharge passage (315) for discharging the fuel in the control chamber to the low pressure portion (12);
A high pressure supply passage (322) for supplying high pressure fuel to the control chamber;
A first valve body (33) for opening and closing between the control chamber and the discharge passage;
A second valve body (36) for opening and closing between the control chamber and the high pressure supply passage;
A piezoelectric actuator (4) that expands and contracts due to charge and discharge of electric charge and drives the first valve body and the second valve body;
And a drive voltage application device (7) for switching the drive voltage applied to the piezoelectric actuator to a first drive voltage and a second drive voltage higher than the first drive voltage.
When the drive voltage is not applied to the piezo actuator, the first valve body closes the space between the control chamber and the discharge passage.
When the first drive voltage is applied to the piezo actuator, only the first valve body is driven among the first valve body and the second valve body, and the space between the control chamber and the discharge passage is opened. He
When the second drive voltage is applied to the piezoelectric actuator, the first valve body is driven to open the space between the control chamber and the discharge passage, and the second valve body is driven to perform the control. A fuel injection valve opened between a chamber and the high pressure supply passage. A first valve chamber (312) in communication with the discharge passage and in communication with the control chamber via communication passages (381, 382, 833, 834),
The first valve body is disposed in the first valve chamber,
The second valve body is disposed in the control chamber,
The piezoelectric actuator, the first valve body and the second valve body are arranged in series;
Of the first valve body and the second valve body, only the first valve body is driven with the extension of the piezoelectric actuator when the first drive voltage is applied,
The fuel injection valve according to claim 1, wherein the second valve body is driven through the first valve body in accordance with the extension of the piezoelectric actuator when the second drive voltage is applied. A displacement transmitting member (83) for transmitting the displacement of the first valve body to the second valve body when the piezoelectric actuator 4 is expanded;
The intermediate spring (84) according to claim 2, further comprising: an intermediate spring (84) biasing the displacement transmitting member with a predetermined set load and closing the first valve body between the first valve chamber and the discharge passage. Fuel injection valve.

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