JP2006161611A - Fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection valve capable of preventing change of lift quantity even in the case wherein a valve body or the like is influenced by surrounding temperature due to the heat, in regard to a fuel injection valve structured to drive a valve member of an outer opening valve structure with a driving member to be extended/shrunken by electrifying. <P>SOLUTION: The fuel injection valve 10 is provided with the valve body 12 (nozzle bodies 25 and 26 or the like in detail) having a valve seat 13, a needle 16 to be inserted inside/outside the nozzle body in the axial direction and to be seated on and separated from the valve seat 13, and a piezoelectric vibrator 17 to be extended and shrunken by electrifying. The fuel injection valve 10 is opened by extending the piezoelectric vibrator 17 to separate the needle 16 outside from the seat. Stopper members 71 and 76 are provided to abut on the valve body 12 to regulate lift quantity of the needle 16 separating from the valve seat 13. Abutment parts of the stopper members 71 and 76 on the valve body 12 are set at positions for moving the stopper members 71 and 76 toward the valve seat side with the valve body 12 when the valve body 12 is swollen (a second stage difference part 12a and a lower end part 72a). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection valve, and is suitably applied to a fuel injection valve that drives a valve member by a driving member such as a piezoelectric element that expands and contracts when energized.

  As a fuel injection device, for example, a fuel injection valve that directly or indirectly injects fuel into a combustion chamber of an internal combustion engine is known. The fuel supplied from the fuel injection valve is mixed with air in the intake pipe or the combustion chamber to form a combustible mixture in the combustion chamber. The combustible air-fuel mixture in the combustion chamber is compressed by piston motion, and then ignited and combusted by an ignition device, and is used as power for the internal combustion engine.

  This type of fuel injection valve includes a valve body and a valve portion having a needle as a valve member that can be seated on and separated from the valve seat of the valve body, and the fuel injection amount is such that the needle is separated from the valve seat. It is measured by the open valve period and the lift amount of the needle. In recent years, there has been a demand for speeding up the responsiveness of the valve portion so that a large injection amount can be obtained in a short time for low fuel consumption and high output.

  As means for speeding up the responsiveness of the valve portion, there is a technique of driving the needle with a driving member that expands and contracts by energization such as a piezoelectric element (see Patent Documents 1 and 2). The drive member lifts and retracts the needle directly by extending and contracting, causing the needle to separate and seat from the valve seat.

  In addition, as a driving member, a piezoelectric element is used in Patent Document 1 and a giant magnetostrictive element is used in Patent Document 2, and in general, both have a temperature characteristic in which the driving member generates heat and thermally expands when energized and magnetic fields are applied. Further, these valve portions have a so-called outer valve opening structure in which the needle can be inserted into and out of the valve body.

In Patent Document 2, a slight gap is provided between the drive member that directly drives the needle and the needle to reduce the influence of temperature characteristics due to thermal expansion.
JP 2002-539370 A Japanese Patent Laid-Open No. 7-227091

  In the prior art according to the above-mentioned patent document, it is possible to suppress the influence of the temperature characteristics caused by the driving member such as the piezoelectric element on the fuel injection valve to the extent that the oil tightness of the valve portion is maintained. However, the lift amount of the fuel injection valve actually mounted on the internal combustion engine may change due to the influence of the ambient temperature due to the heat received from the internal combustion engine. In some cases, there is a problem that it is difficult to accurately measure the injection amount by changing the lift amount.

  For example, when fuel is directly injected into the combustion chamber by means of a fuel injection valve, the fuel injection valve is generally arranged such that the tip side of the valve body faces the combustion chamber. On the other hand, an internal working member such as a needle is immersed in a fuel having a relatively small temperature change. For this reason, a temperature difference may occur between the needle side and the valve body side, that is, the inside and outside of the fuel injection valve, due to the influence of the ambient temperature such as the combustion temperature. In some cases, if the temperature difference between the valve body and the internal working member such as the needle increases, the lift amount changes due to the difference in thermal expansion, and the fuel injection amount changes. There is a demand for valves.

  The present invention has been made in consideration of such circumstances, and its purpose is to drive a valve member having an outer valve opening structure with a drive member that expands and contracts by energization or the like. An object of the present invention is to provide a fuel injection valve that can prevent a change in lift amount even when it is affected by the ambient temperature.

  In order to achieve the above object, the present invention comprises the following technical means.

That is, according to the first to eleventh aspects of the present invention, a valve body having a valve seat, a valve member that can be inserted in the axial direction inside and outside the valve body, and seated on and away from the valve seat; A fuel injection valve that is opened by separating the valve member to the outside by extension of the drive member,
A stopper member that regulates the lift amount of the valve member that contacts the valve body side and separates from the valve seat is provided, and the stopper member and the valve body are provided with a stopper member together with the valve body when the valve body is expanded. It is characterized by a position that moves to the valve seat side.

  According to this, the stopper member that regulates the lift amount of the valve member that contacts the valve body side and separates from the valve seat is provided, and the contact portion between the stopper member and the valve body is formed at the valve body when the valve body is expanded. At the same time, since the stopper member is moved to the valve seat side, it is possible to alleviate or prevent a lift change due to a difference in thermal expansion between the valve body side and the valve member side due to the influence of combustion or the like in the combustion chamber. Even when the stopper member that is in contact with a predetermined position of the valve body that moves to the valve seat side during thermal expansion of the valve body is affected by ambient temperature due to heat received by the fuel injection valve, for example, The lift amount can be maintained at a predetermined value.

  Therefore, even if the tip end side of the valve body or the like is influenced by the ambient temperature due to heat reception, it is possible to prevent the lift amount from changing.

  The contact portion between the stopper member and the valve body may be provided inside the valve body, for example, on the side where the valve seat is located, or on the end surface portion of the valve body on the side opposite to the valve seat.

  In the invention according to claim 2, the stopper member includes an urging member that urges the valve member in the seating direction, and a first stopper and a second stopper that sandwich the urging member to form a predetermined interval. It is characterized by having.

  According to this, the stopper member includes the urging member that urges the valve member in the seating direction, and the first stopper and the second stopper that sandwich the urging member to form a predetermined interval. The axial position of the entire stopper member can be changed so as to reduce or prevent the difference in thermal expansion between the valve member and the valve member. As a result, it is possible to cause the stopper member to follow a change in the valve seat position while maintaining a predetermined interval formed by the first stopper and the second stopper that constitute the stopper member.

  Therefore, even if the tip side of the valve body or the like is affected by the ambient temperature, the lift amount of the valve member can be prevented from changing.

  According to a third aspect of the present invention, the first stopper and the second stopper are formed so that a valve member can be inserted therein, and penetrate at least one of the first stopper and the second stopper inward and outward. A communication hole is provided.

  In a fuel injection valve having a so-called outer valve opening structure that opens when the valve member is separated from the outside, the internal operation members such as the valve member and the stopper member are immersed in the fuel, so that the lift amount is regulated. The stopper member is also immersed in the fuel. Therefore, at the time of so-called valve opening and holding so that the lift amount of the valve member is maximized, there is no predetermined interval between the first stopper and the second stopper constituting the stopper member, so the internal fuel passage toward the valve seat side There is a risk of fuel clogging.

  On the other hand, in the invention according to claim 3, since the communication hole penetrating inward and outward is provided in at least one of the first stopper and the second stopper, the first stopper and the second stopper during the valve opening period. Even if there is a case in which the predetermined interval is lost, fuel can be prevented from being blocked toward the valve seat.

According to a fourth aspect of the present invention, the contact portion is formed on the lower stopper portion side that extends to either the valve seat side of the first stopper and the second stopper disposed on the valve seat side. And
The lower-side stopper portion has a large-diameter shaft portion that is slidable on the inner periphery of the valve body, and the contact portion extends toward the valve seat side of the large-diameter shaft portion. On the other hand, it is arranged so that a predetermined radial gap is provided.

  According to this, any one of the first stopper and the second stopper disposed on the valve seat side as a portion for providing the contact portion between the stopper member and the valve body for relaxing or preventing the lift change. Since it is provided on the side of the lower stopper portion extending to the seat side, it is easy to follow the change in the axial position of the valve seat.

  Further, in the lower stopper portion and the valve body, the lower stopper portion is housed in the inner periphery of the valve body, and slides between the large diameter shaft portion of the lower stopper portion and the inner periphery, that is, the upper portion of the inner periphery. Because it is configured to be movable, even when the stopper member has a relatively long axis, it can be prevented from falling down when moving in the axial direction, and the restriction of the lift amount by the stopper member is smooth and stable. Yes.

  In addition, since a predetermined radial clearance is formed with respect to the inner periphery on the contact portion side extending from the large diameter shaft portion to the valve seat side, the valve body and the stopper member are provided with a valve. A fuel passage for cooling the heat received from the body is formed by a predetermined radial gap.

  Therefore, even if the tip end side of the valve body or the like is affected by the ambient temperature due to heat reception, it is possible to prevent a change in the lift amount of the valve member.

  Further, the invention according to claim 5 is characterized in that the lower stopper portion is provided with a fuel communication hole for communicating the predetermined gap in the radial direction with the inside.

  Thus, when the stopper member is disposed inside the valve body, the lower stopper portion provides a fuel passage for cooling the heat received from the valve body by the fuel communication hole that communicates the predetermined radial direction gap side with the inside. It can be formed effectively.

  In the invention according to claim 6, a support portion for supporting the urging member is extended on the counter valve seat side of the lower side stopper portion, and the support portion is disposed so as to face the valve body. It is characterized by being.

  According to this, the support portion that supports the urging member is extended on the counter valve seat side of the lower stopper portion, and the support portion is disposed so as to face the valve body without coming into contact therewith. ing. As a result, even if the tip of the valve body may be affected by ambient temperature due to heat reception, for example, the lift amount is regulated while following the change in the valve seat position due to thermal expansion of the valve body as a whole. It is possible to prevent the function of the stopper member to be restricted.

  The invention according to claim 7 has a locking member for locking the other to the valve member with respect to one, and the predetermined interval is determined by the thickness of the locking member. Yes.

  Thereby, the predetermined space | interval between a 1st stopper and a 2nd stopper, ie, the lift amount, can be managed with the thickness of the locking member locked to a valve member. Therefore, as a method of assembling a fuel injection valve having a stopper member that relieves or prevents a lift change due to a difference in thermal expansion between the valve body side and the valve member side, the amount of lift can be adjusted by assembling and adjusting the amount of lift. Variations in the lift amount of the fuel injection valve can be suppressed.

  Further, the invention according to claim 8 is characterized in that the valve member has an engaging step that allows the locking member to be locked to the valve member from the outside.

  According to this, it is preferable that the valve member has a engagement direction step which enables the locking member to be locked from the outside with respect to the valve member. As a result, while measuring the predetermined interval, that is, the lift amount, the lift amount can be adjusted by simply inserting and attaching the locking member to the valve member from the outside without disassembling the valve member and the stopper member from the valve body. .

  In the invention according to claim 9, the stopper member has a smaller thermal expansion coefficient than the valve body.

  According to this, it is preferable that a stopper member consists of a material with a small thermal expansion coefficient compared with a valve body. As a result, in the heat change on the internal combustion engine side, for example, the heat change from the low temperature state to the high temperature state, the influence on the lift change due to the difference in thermal expansion between the valve body side and the valve member side is also suppressed by the material of the stopper member itself. Can be achieved.

  In the invention according to claim 10, the stopper member can always contact and follow the valve body.

  According to the eleventh aspect of the present invention, a back pressure chamber is provided between the drive member and the valve member to convert the expansion / contraction operation of the drive member into a hydraulic operation and to perform the lift operation of the valve member by the hydraulic operation. It is characterized by being.

  In general, in a transmission method that converts a mechanical operation into a hydraulic fluid operation, the pressure in the back pressure chamber may fluctuate due to the impact of the fluid due to the relatively quick expansion and contraction of the drive member. On the other hand, in the invention according to the eleventh aspect, since the stopper member for restricting the lift amount of the valve member is provided, even if the back pressure chamber pressure may fluctuate due to the relatively quick expansion / contraction operation of the driving member, the stopper member Can prevent the lift amount from changing.

  Hereinafter, the fuel injection device according to the present invention is applied to an apparatus that injects and supplies fuel to a gasoline engine, and a specific embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view showing a schematic configuration of the fuel injection valve of the present embodiment. FIG. 2 is an enlarged partial cross-sectional view of the main part in FIG. 3A and 3B are views showing the locking member in FIG. 2, in which FIG. 3A is a plan view of the first locking member, and FIG. 3B is a plan view of the second locking member. FIG. 4 is a schematic diagram for explaining a lift amount due to a difference in thermal expansion between the valve body side and the valve member side in FIG. FIG. 5 is a schematic cross-sectional view showing an example of a mounted state in which the fuel injection valve of FIG. 1 is mounted on an internal combustion engine.

  The fuel injection device is used in an internal combustion engine, particularly a gasoline engine, and injects fuel into each cylinder of, for example, a multi-cylinder (for example, four-cylinder) gasoline engine (hereinafter referred to as an engine). As shown in FIG. 5, engine 100 includes a cylinder block (not shown), a cylinder head 102, a piston (not shown), an inner peripheral wall of the cylinder block, a piston, and a ceiling inner wall of cylinder head 102. This is a well-known internal combustion engine including a combustion chamber 106 that is defined. The volume of the combustion chamber 106 increases or decreases as the piston reciprocates. The cylinder head 102 includes an intake port (not shown) that is connected to an intake pipe (not shown) and guides intake and intake air, and an exhaust port (not shown) that is connected to an exhaust pipe (not shown) and discharges exhaust gas. Yes. Here, FIG. 5 shows only one of the four cylinders in the drawing, and FIG. 1 shows a fuel injection valve provided in the cylinder shown in FIG.

  The fuel injection device includes a fuel injection valve 2 that injects fuel. As long as the fuel injection valve 2 is mounted on the engine 100, the fuel injection valve 2 is not limited to a cylinder head or the like attached to the cylinder as shown in FIG. It may be attached.

  The fuel injection valve 2 is supplied with fuel pressurized by a fuel pump (not shown) via a fuel distribution pipe (not shown). The fuel injection valve 2 has a substantially cylindrical shape as shown in FIG. 1, receives fuel from one end, and injects fuel from the other end. The fuel injection valve 2 includes a nozzle body 12, a casing 14, a filter body 15, a needle 16 as a valve member, a piezoelectric vibrator 17 as a drive member, a main piston 18, and stopper members 71 and 76. . An inner hole is formed in the fuel inlet portion on one end side of the fuel injection valve 2 and communicates with an internal fuel passage for supplying fuel into the fuel injection valve 2. A filter 24 is attached to the inner hole to remove foreign matter. When the engine 100 is a direct injection engine, the fuel injection valve 2 directly supplies fuel to the combustion chamber 106 of the cylinder. In this case, in order to set the pressure of the fuel supplied to the combustion chamber 106 to about 2 MPa or more, a predetermined low pressure (for example, 0.2 MPa) fuel sucked up from the fuel tank by the fuel pump is further supplied by a high pressure pump (not shown). Pressurized, and this pressurized predetermined high-pressure fuel (for example, a fuel having a predetermined pressure in the range of 2 to 13 MPa) is supplied to the fuel injection valve 2 via the fuel distribution pipe. The fuel discharged from the fuel pump and the fuel discharged after being further pressurized from the high-pressure pump are each adjusted to a predetermined pressure by a pressure regulator as a fuel pressure adjusting device (not shown).

  Note that the fuel supplied to the fuel injection valve 2 is guided from a fuel tank that is disposed relatively far from a heat source such as a cylinder having the combustion chamber 106, so that the temperature change is relatively small.

  The nozzle body 25 and the casing 14 are fastened by a retaining nut 21 and a knock pin 22 with a packing 26 as an intermediate member interposed therebetween. The nozzle body 25 and the packing 26 jointly constitute the valve body 12. The casing 14 and the filter body 15 are fastened by a retaining nut 11. Fuel passages 23 and 33 pass through the nozzle body 25, the packing 26, the casing 14 and the filter body 15. The pressurized fuel supplied from the common rail flows into the inlet portion of the fuel passage 23 provided in the filter body 15. A filter 24 that removes foreign matters in the fuel is disposed in a portion of the fuel passage 23 formed by the filter body 15. The valve body described in the claims is not limited to the valve body 12 including the nozzle body 25 and the packing 26, and may be configured of the nozzle body 25.

  The nozzle body 25 has a conical surface 13 as an inner peripheral surface that expands in the fuel flow direction. A needle 16 can be separated from and seated on the conical surface 13. Here, the conical surface 13 constitutes a valve seat on which the needle 16 can be separated and seated. Specifically, the contact portion 31 of the needle 16 is separated from and seated on the valve seat 13. The needle 16 is formed in a substantially axial shape, and can reciprocate in the axial direction in the valve body 12 (specifically, the nozzle body 25 and the packing 26). Here, the valve seat 13 and the contact portion 31 constitute a seat portion that functions as an oil-tight function for the valve portion to stop fuel injection.

  In the nozzle body 25 and the packing 26, as shown in FIGS. 1 and 2, stopper members 71 and 76 are arranged so as to always abut against a part of the nozzle body 25 (specifically, the second step portion 12a). ing. As shown in FIG. 2, the stopper members 71 and 76 include a first spring 36, a first stopper 71, and a second stopper 76 as urging members. The first spring 36 urges the needle 16 in the seating direction. The first stopper 71 and the second stopper 76 are disposed so as to sandwich the first spring 36 therebetween, and are configured to form a predetermined gap (hereinafter referred to as an air gap) Ga. Accordingly, the stopper member 71 regulates the lift amount of the needle 16 based on the air gap Ga.

  A first back pressure chamber 35 that accommodates stopper members 71 and 76 is formed inside the nozzle body 25 and the packing 26. Pressurized fuel supplied from the common rail flows into the first back pressure chamber 35 via the fuel passages 23 and 33. Specifically, the packing 26 has a stepped inner periphery at the lower end, and a first back pressure chamber 35 is formed inside by contacting the upper end 12 c of the nozzle body 25. The upper end portion 12c is formed with a stepped inner periphery toward the valve seat 13 side, and has a first step portion 12b and a second step portion 12a. The second step portion 12a and a lower end portion 72a described later constitute an abutting portion described in the claims.

  The 1st stopper 71 and the 2nd stopper 76 consist of a substantially cylindrical body, and the needle 16 is formed in the inside so that insertion is possible. As shown in FIG. 2, the first stopper 71 has a lower-side stopper portion 72, a first support portion 73, and an upper-side stopper portion 74 from the valve seat 13 side upward in FIG. 2. Yes. The lower side stopper 72 is housed and held on the inner periphery 12h of the nozzle body 25, and is always in contact with the second stepped portion 12a. The 1st support part 73 is formed larger than the outer diameter of the 1st spring 26, and is supporting the 1st spring 36 so that expansion-contraction is possible. The upper-side stopper portion 75 is formed in a substantially cylindrical shape, and guides the first spring 36 on the outer peripheral side so as to be extendable and contractible. In addition, it is preferable that the 1st support part 73 is arrange | positioned so that the valve body 25 (specifically 1st level | step-difference part 12b) may be opposed to an axial direction.

  In the present embodiment, the second stopper 71 (specifically, the upper stopper portion 74) is provided with communication holes (hereinafter referred to as first communication holes) 75a and 75b penetrating inward and outward. As a result, even if the needle 16 is fully lifted and the air gap Ga disappears, the fuel flow toward the valve seat 13 via the fuel passages 23 and 33 and the first back pressure chamber 35 is blocked. Can be prevented.

  Furthermore, in the present embodiment, the lower-side stopper 72 has a large-diameter shaft portion 72b that can slide on the inner periphery 12h. The lower end portion 72a extends toward the valve seat 13 of the large diameter shaft portion 72b, and the lower end portion 72a side is formed so as to have a predetermined radial clearance with respect to the inner periphery 12h.

  Furthermore, in the present embodiment, as shown in FIG. 2, the lower stopper 72 is provided with second communication holes 75c and 75d as fuel communication holes that communicate the gap in the predetermined radial direction with the inside.

  The second stopper 76 has a main body as a second support portion that supports the first spring 36, and a locking member 77 that locks the needle 16. Note that the second stopper 76 may be either one in which the main body and the locking member 77 are integrated by assembly, or one in which the main body and the locking member 77 are integrally formed. In the following description of the present embodiment, it is assumed that the second stopper 76 is formed as a separate member on the main body and the locking member 77 and is integrated by assembling them. By forming the locking member 77 as a separate member in the second stopper 76, the air gap Ga can be determined based on the thickness of the locking member 77 in the assembly step of adjusting the air gap Ga.

  In the present embodiment, as shown in FIG. 3, the locking member 77 is constituted by a first locking member 77a and a second locking member 77b. The first locking member 77a and the second locking member 77b are formed in a substantially horseshoe-shaped C-ring shape. As shown in FIG. 2, the first locking member 77 a and the second locking member 77 b are formed so that a C-ring-shaped opening can be inserted into the radial step 34 of the needle 16. Thereby, the first locking member 77 a and the second locking member 77 b can be inserted into the radial step 34 from the outside in the radial direction and locked to the needle 16. At this time, while measuring the air gap Ga or the lift amount of the needle 16, the locking member 77 (specifically, the first and second locking members in detail) without disassembling the needle 16 and the stopper members 71 and 76 from the nozzle body 25. 77a, 77b) can be adjusted by assembling the lift amount only by inserting and assembling the needle 16 from the outside. Therefore, it is possible to improve the assembling performance in the assembling process for adjusting the air gap Ga.

  In addition, when forming the locking member 77 as a separate member in the 1st locking member 77a and the 2nd locking member 77b, it is preferable to comprise as follows. One of the first locking member 77a and the second locking member 77b (the first locking member 77a in this embodiment) holds the biasing force of the first spring 35 and is fixed to the needle 16. Strength securing section. The other is a spacer for adjusting the lift amount. Thereby, in the assembly method of selecting and adjusting the air gap Ga according to the thickness of the locking member 77, the first locking member 77a is used without waste in the fuel injection valve 10 manufactured in the manufacturing process. Since only the second locking member 77b needs to be replaced as a thickness selection, the yield is reduced and the productivity can be improved.

  On the downstream side of the valve seat 13, as shown in FIG. The needle 16 (specifically, the contact portion 31) is seated on and off from the valve seat, whereby fuel is injected and stopped from the fuel injection valve 2. Specifically, when the needle 16 is lifted in the direction A in FIG. 1, the needle 16 is separated from the valve seat 13, the internal fuel passage is opened to the outside, and fuel is injected. On the other hand, when the needle 16 moves in the direction B in FIG. 1, the needle 16 is seated on the valve seat 13, and the space between the downstream side of the valve seat 13 and the internal fuel passage is closed to inject fuel. Stop. In the following description of the present embodiment, the direction A is called the valve opening direction, and the direction B is called the valve closing direction. The fuel injection amount of the fuel injection valve 10 is measured by the lift amount of the needle 16 and the valve opening period. When the needle 16 is seated on the valve seat 13, fuel injection is stopped, and when the needle 16 is separated from the valve seat 13, fuel is injected.

  In the present embodiment, a so-called injection hole for injecting fuel is not provided on the downstream side of the valve seat 13, but the injection hole is provided on the downstream side of the valve seat 13, that is, on the tip side of the fuel injection valve 10. You may make it provide.

  The casing 14 has a fixed portion 45 and a main cylinder portion 46. The fixed portion 45 accommodates the piezoelectric vibrator 17 so as to be extendable and contractible in a direction parallel to the central axis (not shown) of the needle 16. The counter valve seat side end portion 17 b of the piezoelectric vibrator 17 is joined to a fixed packing 47 fixed to the fixed portion 45. Accordingly, the piezoelectric vibrator 17 can expand and contract in accordance with the driving energy supplied through the power supply line 44, and the valve seat side end portion 17 a can be advanced and retracted into the main cylinder portion 46. The main cylinder portion 46 accommodates the main piston 18 formed in a columnar shape so as to be capable of reciprocating in the central axis direction. The outer diameter of the main piston 18 is set larger than the outer diameter of the enlarged diameter portion 30 of the needle 16. The central axis of the main piston 18 extends parallel to the central axis (not shown) of the needle 16. A space between the outer peripheral wall of the main cylinder 46 and the inner peripheral wall of the main piston 18 slidably contactable with the main cylinder 46 is sealed by an O-ring 48. The counter valve seat side end 18b of the main piston 18 is in contact with the end face of the valve seat side end 17a of the piezoelectric vibrator 17 at its end face. Thereby, the main piston 18 can reciprocate in the main cylinder portion 46 as the piezoelectric vibrator 17 expands and contracts.

  The main cylinder portion 46 is a valve seat side portion of the inner peripheral wall thereof and forms a second back pressure chamber 50 where the valve seat side end portion (anti-piezoelectric vibrator side end portion) 18a of the main piston 18 faces. The counter valve seat side end (main piston side end) of the second back pressure chamber 50 is formed larger in diameter than the first back pressure chamber 35, and the valve seat side end of the second back pressure chamber 50 is the first end. It is formed with a smaller diameter than the one back pressure chamber 35. As a result, the main piston 18 does not come into contact with the needle 16. The second back pressure chamber 50 communicates at its valve seat side end with the counter valve seat side end of the first back pressure chamber 35, and fuel flows from the first back pressure chamber 35. The main piston 18 receives the fuel pressure in the second back pressure chamber 50 in the valve closing direction B. The first back pressure chamber 35 and the second back pressure chamber 50 jointly constitute the back pressure chamber described in the claims. The second back pressure chamber 50 is provided with a second spring (not shown) made of a disc spring. The second spring 51 urges the main piston 18 in the valve closing direction B.

  Next, the operation of the fuel injection valve 10 of the present embodiment having the above-described configuration will be described. When the vehicle engine key is set to the IG position and an ignition switch (not shown) is turned on, the fuel pump is driven, and the fuel is sucked into the fuel tank by the fuel pump. The sucked fuel is regulated by a pressure regulator, and a predetermined low pressure fuel is supplied to the high pressure pump. The predetermined low pressure fuel is pressurized by the high pressure pump, and the pressurized fuel is supplied to the fuel distribution pipe. The fuel supplied to the fuel distribution pipe is regulated to a predetermined high-pressure fuel by a pressure regulator and supplied to the fuel injection valve 10 from each distribution port in the fuel distribution pipe.

  When fuel is injected from the fuel injection valve 2, driving energy is supplied to the piezoelectric vibrator 17, and the piezoelectric vibrator 17 expands and presses the main piston 18 in the valve opening direction A against the urging force of the second spring. The piston 18 is in a state where the volume of the second back pressure chamber 50 is minimized. At this time, when the fuel pressure in the first back pressure chamber 50 reaches a predetermined pressure or becomes equal to the fuel pressure in the second fuel chamber 35, the needle 16 receives the fuel pressure in the first back pressure chamber 50, and the first spring. The needle 16 is lifted in the valve opening direction against the urging force of 36. When the needle 16 starts to lift in the valve opening direction, the needle 16 moves away from the valve seat 13, so that fuel injection is started.

  On the other hand, when the fuel injection is stopped, the driving energy supplied to the piezoelectric vibrator 17 is released and the piezoelectric vibrator 17 is contracted. When the piezoelectric vibrator 17 contracts, the main piston 18 moves in the valve closing direction B by the biasing force of the second spring. As a result, the main piston 18 decreases the fuel pressure in the second back pressure chamber 50 and further decreases the fuel pressure in the first back pressure chamber 35 communicating with the second back pressure chamber 50. Since the needle 16 is urged in the valve closing direction by the urging force of the first spring 36, the needle 16 is closed in the valve closing direction B, that is, the direction in which the valve seat 13 is seated when the fuel pressure in the second back pressure chamber 50 decreases. Reduce the lift. When the needle 16 is seated on the valve seat 13, the downstream side of the valve seat 13 and the internal fuel passage are closed, so that fuel injection is completed. By adjusting the energization period to the piezoelectric vibrator 17, the injection period of the fuel (fuel spray) injected from the fuel injection valve 10, that is, the fuel injection amount is adjusted.

  Here, as shown in FIG. 5, the fuel injection valve 10 of the present embodiment is arranged such that the tip end side of the valve body 12 and the like is directed to the combustion chamber 106. As shown in FIG. 5, in the fuel injection valve 10, a part of the valve body 12 is accommodated in a stepped communication hole of the cylinder head 102 via a gasket 103 as a seal member. The nozzle body 25 and the tip end side of the packing 26 constituting the valve body 12 on the middle and lower side may be exposed to the flame and combustion gas generated in the combustion chamber 106. The nozzle body 25, the packing 26, and the like may be heated to about 100 to 150 ° C. The cylinder head 102 is cooled and kept at about 80 ° C. (in some cases 60 to 100 ° C.) by the effect of a water cooling type cooling device such as a water jacket on the engine 100 side. In a wide range of operating states such as a cold state such as a driving state where the vehicle stops idling from traveling in a high load state, there is a possibility of changing from outside air temperature to 100 ° C.

  Therefore, in the structure of directly driving the needle by expansion and contraction of the piezoelectric vibrator 17 as in the conventional fuel injection valve, when a thermal change from the low temperature state to the high favor state due to combustion occurs, for example, on the engine side, The lift amount may change in a decreasing direction, and the fuel injection amount may change. Specifically, the valve body 12 such as the nozzle body 25 and the packing 26 thermally expands due to high temperature, and extends downward in FIG. When the valve body 12 side extends downward, the valve body 12 itself (specifically, the valve seat 13) also moves downward, so that the initial lift position of the valve seat 13, that is, the needle 16, also moves downward. As a result, the lift amount is reduced, so that the fuel injection amount may change (specifically, decrease) by the reduction amount of the lift amount.

  In contrast, the fuel injection valve 2 of the present embodiment includes a stopper member 71 that defines the lift amount of the needle 16, and includes the stopper member 71 (specifically, the lower side stopper portion 72) and the valve body 12 (specifically, the nozzle body). The second step portion 12a of the nozzle body 25 is relatively close to the valve seat 13 side. Specifically, the lower end portion 72a on the stopper member 71 side is always brought into contact with the second stepped portion 12a on the valve seat 13 side inside the valve body 12 so as to follow.

  By adopting such a configuration, the stopper members 71 and 76 that define the lift amount of the needle 16 are used for the valve due to thermal expansion of the valve body 12 (in the schematic diagram of FIG. 4, for example, the valve body 12 expands by a dimension L). The change in the lift amount due to the difference in thermal expansion between the valve body 12 side and the needle 16 side can be mitigated or prevented by following the change in the axial position of the seat 13. Specifically, as shown in FIG. 4, even when the valve body 12 is expanded by the dimension L, the stopper members 71 and 76 and the internal working member on the needle 16 side are immersed in fuel having a relatively small temperature change. Therefore, the distance between the support portion 73 of the first stopper 72 and the first step portion 12b of the nozzle body 25 in the axial direction is only reduced. As a result, since the stopper members 71 and 76 as a whole move following the change in the axial position of the valve seat 13, the air gap Ga1 before expansion of the dimension L and the air gap Ga2 after expansion are maintained at substantially the same size. it can. Therefore, even if the ambient temperature is affected by the heat received on the valve body 12 side due to a heat change on the engine 100 side or the like, it is possible to prevent the lift amount of the needle 16 from changing.

  Next, functions and effects of the present embodiment will be described. (1) In the present embodiment, the stopper members 71 and 76 that define the lift amount of the needle 16 are provided, and the stopper members 71 and 76 (specifically, the lower side stopper portion 72 is provided). ) And the valve body 12 (specifically, the nozzle body 25 and the packing 26), the lower end portion 72 a on the stopper members 71, 76 side is a second portion located on the valve seat 13 side inside the valve body 12. It is comprised so that it may contact | abut on the level | step-difference part 12a. Thereby, the said contact part can be made into the position which moves the stopper members 71 and 76 to the valve seat 13 side with the valve body 12 at the time of the thermal expansion of the valve body 12. Therefore, since the contact portion is set to a position where the stopper member 71 is moved to the valve seat 13 side together with the valve body 12 when the valve body 12 is thermally expanded, the valve body 12 side due to the influence of combustion in the combustion chamber 106 or the like. And the change in lift due to the difference in thermal expansion between the needle 16 and the needle 16 can be reduced or prevented. Ambient temperature due to heat received by the fuel injection valve 10, for example, by the stopper members 71 and 76 that are in contact with a predetermined position (second step portion 12 a) of the valve body 12 that moves toward the valve seat 13 when the valve body 12 is thermally expanded. Even in the case of being affected by this, the lift amount of the needle 16 can be maintained at a predetermined value (in this embodiment, the air gap corresponding to the full lift amount is a predetermined value of Ga1 = Ga2).

  Therefore, even if the tip end side such as the valve body 12 is affected by the ambient temperature due to heat reception, it is possible to prevent the lift amount from changing.

  (2) More specifically, as the stopper members 71 and 76 that define the lift amount, a first spring 36 that urges the needle 16 in the seating direction, and an air gap Ga is formed by sandwiching the first spring 36. Since the first stopper 71 and the second stopper 76 are provided, the axial positions of the stopper members 71 and 76 as a whole are changed so as to reduce or prevent the difference in thermal expansion between the valve body 12 side and the needle 16 side. As a result, it is possible to cause the stopper members 71 and 76 to follow the change in the position of the valve seat 13 while maintaining the air gap Ga formed by the first stopper 71 and the second stopper 76 as the whole stopper members 71 and 76. It is. Therefore, even if the tip side of the valve body 12 or the like may be affected by the ambient temperature, it is possible to prevent the lift amount of the needle 16 from changing.

  (3) In the present embodiment, it is preferable that the second stopper 71 (specifically, the upper side stopper portion 74) is provided with first communication holes 75a and 75b penetrating inward and outward.

  In the fuel injection valve 10 having a so-called outer valve opening structure that opens when the needle 16 is separated from the outside, the internal operation member such as the needle 16 is immersed in the fuel, so that the lift amount of the needle 16 is regulated. The stop member to be immersed is also immersed in the fuel. Therefore, at the time of so-called valve opening and holding so that the lift amount of the needle 16 is maximized (full lift), the air gap Ga is lost, so that the fuel in the internal fuel passage toward the valve seat 13 may be blocked. is there.

  On the other hand, in the present embodiment, since the first communication holes 75a and 75b are provided to communicate the inside and outside of the stopper members 71 and 76, the needle 16 may be fully lifted to eliminate the air gap Ga. Even so, it is possible to prevent the fuel flow toward the valve seat 13 from passing through the fuel passages 23 and 33 and the first back pressure chamber 35.

  (4) Furthermore, in this embodiment, the lower-side stopper 72 has a large-diameter shaft portion 72b that can slide on the inner periphery 12h. It is preferable that the lower end portion 72a extends toward the valve seat 13 of the large diameter shaft portion 72b, and the lower end portion 72a side is formed so as to provide a predetermined radial clearance with respect to the inner periphery 12h. .

  According to this, it arrange | positions in the valve seat 13 side among the 1st stopper 71 and the 2nd stopper 76 as a site | part which provides the contact part of the stopper members 71 and 76 and the valve body 12 for relaxing or preventing a lift change. Since the first stopper 71 is provided on the lower stopper portion 72 side extending to the valve seat 13 side of the first stopper 71, it is easy to follow the change in the axial position of the valve seat 13 .

  Further, in the lower stopper portion 72 and the valve body 12, the lower stopper portion 72 is accommodated in the inner periphery of the valve body 12, and the large diameter shaft portion 72b of the lower stopper portion 72 and the upper portion of the inner periphery 12h. It is slidable on the side. Thus, even when the stopper members 71 and 76 are relatively long shafts, the stopper members 71 and 76 can be prevented from falling during movement in the axial direction, and the restriction of the lift amount by the stopper members 71 and 76 is smoothly and stably performed. Yes.

  Further, the contact portion side extending from the large-diameter shaft portion 72b to the valve seat 13 side is formed with a predetermined radial clearance with respect to the inner periphery 12h, so that the valve body 12 and the lower-side stopper portion are formed. A fuel passage that cools the heat received from the valve body 12 is formed by a predetermined radial gap.

  Therefore, even if the tip end side of the valve body 12 or the like is affected by the ambient temperature due to heat reception, the change in the lift amount of the needle can be reliably prevented.

  (5) Furthermore, in the present embodiment, it is preferable that the lower stopper 72 is provided with second communication holes 75c and 75d that allow the predetermined radial clearance to communicate with the inside. Thus, when the stopper members 71 and 76 are disposed inside the valve body 12, the lower stopper portion 72 allows the fuel to flow between the predetermined radial direction gap side and the inside through the second communication holes 75c and 75d. The fuel passage for cooling the heat received from the valve body 12 can be effectively formed by the second communication holes 75c and 75d.

  (6) Furthermore, in the present embodiment, a support portion 73 that supports the first spring 36 is extended on the counter valve seat side of the lower side stopper portion 72, and the support portion 73 is connected to the valve body 12 ( In detail, it arrange | positions so as to oppose the 1st level | step difference part 12b), without contacting. Thus, even if the tip end side of the valve body 12 or the like is affected by the ambient temperature due to heat reception, the stopper members 71 and 76 as a whole follow the change in the position of the valve seat 13 due to the thermal expansion of the valve body 12. The function of the stopper members 71 and 76 for regulating the lift amount can be prevented from being restricted.

  (7) Furthermore, the second stopper 76 has a locking member 77 that locks the needle 16, and the air gap Ga is controlled by the thickness of the locking member 77 in the assembly step of adjusting the air gap Ga. decide. Thereby, the air gap Ga, that is, the lift amount can be managed by the thickness of the locking member 77. Therefore, as a method of assembling the fuel injection valve 10 having the stopper members 71 and 76 that relieve or prevent the lift change due to the difference in thermal expansion between the valve body 12 side and the needle 16 side, the lift amount is assembled and adjusted. The variation in the lift amount of the individual fuel injection valves 10 to be produced is suppressed.

  (8) In this embodiment, the locking member 77 is composed of the first locking member 77a and the second locking member 77b, and the first locking member 77a and the second locking member 77b are the needles 16. It is preferable that it is formed so as to be insertable into the radial step 34. Accordingly, the first locking member 77a and the second locking member 77b can be inserted into the needle 16 from the outside in the radial direction and locked to the needle 16. At this time, while measuring the air gap Ga or the lift amount of the needle 16, the locking member 77 (specifically, the first and second locking members in detail) without disassembling the needle 16 and the stopper members 71 and 76 from the nozzle body 25. 77a, 77b) can be adjusted by assembling the lift amount only by inserting and assembling the needle 16 from the outside. Therefore, it is possible to improve the assembling performance in the assembling process for adjusting the air gap Ga.

  (9) Furthermore, in this embodiment, one of the first locking member 77a and the second locking member 77b (the first locking member 77a in this embodiment) holds the biasing force of the first spring 35. A structural strength securing portion for fixing to the needle 16 is used. The other is a spacer for adjusting the lift amount. Thereby, in the assembly method of selecting and adjusting the air gap Ga according to the thickness of the locking member 77, the first locking member 77a is used without waste in the fuel injection valve 10 manufactured in the manufacturing process. Since only the second locking member 77b needs to be replaced as a thickness selection, the yield is reduced and the productivity can be improved.

  (10) The stopper members 71 and 76 are preferably made of a material having a smaller thermal expansion coefficient than the valve body 12. Thereby, in the heat change on the engine side, for example, the heat change from the low temperature state to the high temperature state, the lift change due to the difference in thermal expansion between the valve body 12 side and the needle 16 side is also caused by the material of the stopper members 71 and 76 itself. Can be suppressed.

  (11) In the present embodiment, the back pressure between the piezoelectric vibrator 17 and the needle 16 is such that the expansion / contraction operation of the piezoelectric vibrator 17 is converted into a hydraulic operation and the needle 16 is lifted by the hydraulic operation. A chamber 50 is provided.

  In general, in a transmission method that converts a mechanical operation into a fluid operation using hydraulic pressure, the fuel pressure in the back pressure chamber 50 may fluctuate due to a fluid impact caused by a relatively quick expansion and contraction operation of the piezoelectric vibrator 17.

  In contrast, in the present embodiment, since the stopper members 71 and 76 for regulating the lift amount of the needle 16 are provided, the fuel pressure in the back pressure chamber 50 may fluctuate due to the relatively quick expansion and contraction of the piezoelectric vibrator 17. However, the lift amount can be prevented from changing by the stopper members 71 and 76.

(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

  In the second embodiment, in the stopper members 71 and 76 described in the first embodiment, as shown in FIG. 7, the stopper member 171 is not held on the inner periphery 12 i, and is in contact with the valve body 112. Is the first step 112b. FIG. 6 is a cross-sectional view showing a schematic configuration of the fuel injection valve of the present embodiment. FIG. 7 is an enlarged partial cross-sectional view of the main part in FIG. FIG. 8 is a schematic diagram for explaining the lift amount due to the difference in thermal expansion between the valve body side and the valve member side in FIG.

  As shown in FIG. 7, the stopper members 171 and 76 have a first stopper 171, a second stopper 76, and a first spring 36. The first stopper 171 includes an upper stopper portion 174 and a support portion 173. As shown in FIG. 7, the support portion 173 is configured to always contact and follow the first stepped portion 112b.

  Even with such a configuration, substantially the same effect as that of the first embodiment can be obtained. Specifically, as shown in the schematic diagram of FIG. 8, when the valve body 12 is thermally expanded by the dimension L, the air gap Ga1 before the expansion of the dimension L and the air gap Ga3 after the expansion are almost the same size, so that it does not matter. The lift change can be suppressed to a small extent.

(Other embodiments)
In the embodiment described above, the valve body is not limited to the valve body 12 including the nozzle body 25 and the packing 26, and may be configured of the nozzle body 25.

It is sectional drawing which shows schematic structure of the fuel injection valve of the 1st Embodiment of this invention. It is the fragmentary sectional view which expanded the principal part in FIG. FIG. 3A is a plan view of the first locking member, and FIG. 3B is a plan view of the second locking member. It is a schematic diagram explaining the lift amount in the thermal expansion difference of the valve body side and valve member side in FIG. FIG. 2 is a schematic cross-sectional view showing an example of a mounted state in which the fuel injection valve of FIG. 1 is mounted on an internal combustion engine. It is sectional drawing which shows schematic structure of the fuel injection valve of 2nd Embodiment. It is the fragmentary sectional view which expanded the principal part in FIG. It is a schematic diagram explaining the lift amount in the thermal expansion difference of the valve body side and valve member side in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel injection valve 12 Valve body 12a 2nd level | step difference part (contact part)
13 Valve seat 16 Needle (Valve member)
17 Piezoelectric vibrator (drive member)
18 Main piston 25 Nozzle body 26 Packing (intermediate member)
34 radial step 35 first back pressure chamber 36 first spring (biasing member)
50 First back pressure chamber 71 First stopper member (stopper member)
72 Lower side stopper part 72a Lower end part 72b Large diameter shaft part 73 Support part 74 Upper side stopper part 75a, 75b First communication hole (communication hole)
75c, 75d Second communication hole (fuel communication hole)
76 Second stopper member (stopper member)
77 Locking members 77a, 77b First locking member, Second locking member 100 Engine (internal combustion engine)
102 Cylinder head 103 Gasket 106 Combustion chamber

Claims (11)

A valve body having a valve seat;
A valve member that is insertable in an axial direction inside and outside the valve body, and that is seated and separated from the valve seat;
A drive member that expands and contracts when energized,
In the fuel injection valve that opens by separating the valve member to the outside by extension of the drive member,
A stopper member that contacts the valve body side and regulates a lift amount of the valve member that is separated from the valve seat;
The fuel injection valve according to claim 1, wherein a contact portion between the stopper member and the valve body is a position where the stopper member is moved to the valve seat side together with the valve body when the valve body is expanded. The stopper member is
A biasing member that biases the valve member in a seating direction;
2. The fuel injection valve according to claim 1, further comprising a first stopper and a second stopper that sandwich the biasing member to form a predetermined interval. The first stopper and the second stopper are formed so that the valve member can be inserted therein,
The fuel injection valve according to claim 1 or 2, wherein a communication hole penetrating inward and outward is provided in at least one of the first stopper and the second stopper. The abutting portion is formed on a lower stopper portion that extends to the valve seat side of either the first stopper or the second stopper and is disposed on the valve seat side,
The lower-side stopper portion has a large-diameter shaft portion that can slide on the inner periphery of the valve body,
4. The abutting portion extends toward the valve seat side of the large-diameter shaft portion, and is arranged so that a predetermined radial clearance is provided with respect to the inner periphery. The fuel injection valve described in 1. 5. The fuel injection valve according to claim 4, wherein the lower-side stopper portion is provided with a fuel communication hole that communicates the predetermined radial direction gap side with the inside. On the counter valve seat side of the lower side stopper portion, a support portion for supporting the urging member is extended,
6. The fuel injection valve according to claim 4, wherein the support portion is disposed so as to face the valve body. 2. The device according to claim 1, further comprising: a locking member that locks the other to the valve member, wherein the predetermined interval is determined by a thickness of the locking member. The fuel injection valve according to claim 6. 8. The fuel injection valve according to claim 7, wherein the valve member has an engaging step that allows the locking member to be locked to the valve member from the outside. The fuel injection valve according to any one of claims 1 to 8, wherein the stopper member has a smaller coefficient of thermal expansion than the valve body. The fuel injection valve according to any one of claims 1 to 9, wherein the stopper member always abuts and follows the valve body. A back pressure chamber is provided between the drive member and the valve member, which converts an expansion / contraction operation of the drive member into a hydraulic operation and causes the valve member to perform a lift operation by the hydraulic operation. The fuel injection valve according to any one of claims 1 to 10.

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