JP4842293B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve.

  Conventionally, as a fuel injection valve, for example, in an internal combustion engine in which fuel is directly injected into a cylinder, a needle as a “valve member” that opens and closes an injection hole, a pressure control chamber that adjusts an oil pressure for driving the needle, A piston as a "hydraulic pressure transmission member" that transmits the displacement of the actuator via hydraulic pressure and increases or decreases the pressure in the pressure control chamber is provided. The needle is lifted by the pressure change in the pressure control chamber, and high pressure fuel is cylindered from the nozzle hole. Some of them are injected into the inside (see Patent Document 1). In this type of fuel injection valve, a first fuel chamber and a second fuel chamber communicating with the pressure control chamber are formed at both shaft end portions of the piston, respectively. It is connected to a low-pressure fuel passage for returning excess fuel such as fuel to the fuel tank.

  In the apparatus disclosed in Patent Document 1 as a kind of such fuel injection valve, the second fuel chamber is connected to a high-pressure fuel passage that supplies fuel corresponding to the fuel injection pressure to the nozzle hole of the fuel injection valve. Yes. In this technique, the pressure control chamber is increased from the fuel injection pressure by the displacement of the actuator, and the injection and injection stop are performed based on the operating principle of lifting the needle in the valve opening direction. The differential pressure between the first fuel chamber and the second fuel chamber is reduced. This action of reducing the differential pressure makes it possible to suppress fuel leakage from the pressure control chamber and the first fuel chamber to the second fuel chamber.

In addition, in the device disclosed in Patent Document 2 as another kind of fuel injection valve, both the shaft end portions of the piston, that is, the shaft end portions on the first fuel chamber side and the second fuel chamber side, in the outer sliding portion. An annular groove is provided. In this technique, fuel that enters the clearance between the piston and the sliding hole that holds the piston slidably (hereinafter referred to as sliding clearance) is held in the annular groove, and the annular groove An oil film is formed between the sliding portion on the outer periphery of the piston and the sliding hole by the fuel inside. By such an oil film forming action, the sliding resistance that becomes a cause of wear is suppressed, and the sliding characteristics can be guaranteed.
JP 2006-214317 A JP 2004-225626 A

  By combining the devices disclosed in Patent Documents 1 and 2, it should be possible to achieve both fuel leakage suppression from the first fuel chamber to the second fuel chamber and guarantee of sliding characteristics. However, as a result of diligent research conducted by the present inventors, it has been found that there is a concern that, if an attempt is made to suppress the fuel leakage, there is a concern that the sliding resistance is increased and the sliding characteristics cannot be guaranteed. It was. The reason will be described below.

  In the device disclosed in Patent Document 1, when the fuel injection valve is injected, an acting force that increases the first fuel chamber from the fuel injection pressure at the shaft end opposite to the shaft end on the first fuel chamber side, that is, an actuator. A large force that presses and drives the piston in the axial direction is applied by the extension force and the fuel injection pressure in the second fuel chamber. At this time, the piston has a sliding clearance with respect to the sliding hole. By introducing high pressure fuel corresponding to the fuel injection pressure into the second fuel chamber, the piston is placed between the first fuel chamber and the second fuel chamber. Since the differential pressure is made small, fuel leakage during that period is suppressed.

  However, when the above large force acts on the piston, it tilts with respect to the sliding hole in the range of the sliding clearance, and as a result, it slides at the portion of the tilted axial end of the piston that is pressed against the sliding hole. The dynamic friction force may increase. Even if a plurality of annular grooves are provided in the sliding portion on the outer periphery of the shaft end portion of such a piston according to the device disclosed in Patent Document 2, the tip end side of the sliding portion of the shaft end portion The sliding section between the annular grooves or the sliding section between the annular grooves may cause oil film breakage. In this case, if the sliding portion of the piston and the sliding hole move relative to each other, the fuel is not always guided to the sliding section, so that it is difficult to form an oil film and the sliding characteristics are impaired.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a fuel injection valve that achieves both fuel leakage suppression from the first fuel chamber to the second fuel chamber and guarantee of sliding characteristics. It is to provide.

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

That is, according to the first to fifth aspects of the present invention, the valve member that opens and closes the nozzle hole, the pressure control chamber that applies the pressure in the valve opening direction to the shaft end of the valve member on the side opposite to the nozzle hole, and the nozzle hole A fuel injection valve for injecting fuel by increasing the pressure of the pressure control chamber from the fuel pressure of the high pressure fuel passage,
An actuator that generates displacement by energization, a piston that transmits the displacement of the actuator via hydraulic pressure, and increases or decreases the pressure in the pressure control chamber, and the shaft end of the actuator, the piston, and at least the valve member on the side opposite to the injection hole A housing for housing,
The piston is slidably supported on the inner periphery of the housing, and one axial end of both axial ends of the piston is formed by one axial end and the inner periphery of the housing. A first fuel chamber communicating with the control chamber is provided, and the other axial end portion cooperates with the actuator, and a second fuel chamber formed by the other axial end portion and the inner periphery of the housing is provided. ,
At least a specific axial end portion of both axial end portions is a groove portion formed at a plurality of locations in the circumferential direction of the sliding portion and is inclined in the axial direction in the sliding portion sliding on the inner periphery. A groove portion that extends in the inclined direction and communicates with a specific fuel chamber that is in contact with the end portion in the specific axial direction of the first fuel chamber and the second fuel chamber, and adjacent groove portions extending in the inclined direction are spaced apart in the circumferential direction. while being spaced overlaps each other in the axial direction, the inner periphery of the housing, the sliding portion of the piston slidably supports, and defining the first fuel chamber, and a second fuel chamber slides The piston that has a moving hole and cooperates with the actuator is a large-diameter shaft portion that is supported by the sliding hole, and a small-diameter shaft portion that is smaller in diameter than the large-diameter shaft portion and that is integrally linked to the actuator. The small diameter shaft portion is configured to be able to contact the large diameter shaft portion and Large-diameter shaft portion, characterized in that the groove in the sliding portion at both axial ends are formed.

In this invention, the piston slides on the inner periphery of the housing in order to increase or decrease the pressure in the pressure control chamber in response to the displacement of the actuator.
The sliding portion supported so as to be slidable on the inner periphery at the axial end portion of the piston has a groove portion that inclines in the axial direction and extends in the inclined direction, and communicates with a specific fuel chamber in contact with the axial end portion. However, it is set as the structure (henceforth 1st structure) provided in the multiple places of the circumferential direction. With such a configuration, the fuel for forming the oil film is always supplied from the fuel chamber in contact with the end portion in the axial direction to the grooves provided at a plurality of locations in the circumferential direction. Therefore, regardless of the sliding state of the piston, the groove for forming the oil film is supplied to the groove formed in the sliding portion at the axial end of the piston without interruption, and is always held. The

Moreover, in addition to the first configuration, the adjacent groove portions are arranged at intervals in the circumferential direction in the sliding portion and overlap each other in the axial direction (hereinafter, second configuration). Therefore, the fuel that is always held in the adjacent groove portions as described above can be guided from both the axial direction and the circumferential direction to the sliding section sandwiched between the groove portions during the sliding movement of the piston. .
Further, the small-diameter shaft portion can be brought into contact with the large-diameter shaft portion, and such a large-diameter shaft portion has a configuration in which a groove portion is provided in the sliding portion at both axial end portions so that the small-diameter shaft portion is As a result, the sliding part at both ends in the axial direction of the large-diameter shaft part is inclined in the range of the sliding clearance with the sliding hole. Even if the sliding portion at the end of the direction is pressed against the sliding hole, the sliding frictional force is suppressed by the groove, and as a result, the sliding characteristics can be easily guaranteed.

  According to the first aspect of the present invention configured as described above, it is possible to obtain a fuel injection valve that achieves both the suppression of fuel leakage from the first fuel chamber to the second fuel chamber and the guarantee of sliding characteristics in the piston.

  The invention according to claim 2 is characterized in that, among the plurality of groove portions, a specific group of groove portions are integrally connected and constitute a spiral groove.

  According to such a configuration, a specific group of groove portions are integrally formed into a spiral groove. Therefore, the extension range extending in the inclination direction of the groove portion, in other words, the circumferential range in which the groove portion is formed is limited, and the fuel injection valve having excellent productivity compared with the case where a plurality of such groove portions are formed. Obtainable.

  Further, the invention according to claim 3 is characterized in that all of the plurality of grooves are integrally connected.

  According to such a configuration, all of the plurality of groove portions are formed in a spiral spiral groove. Therefore, it is possible to reliably provide a fuel injection valve having excellent productivity.

  According to a fourth aspect of the present invention, it is preferable that the sliding portion is provided with an annular groove that is annular and communicates with the groove portion at the opposite end of the groove portion from the specific fuel chamber.

In this invention, while the groove portions are provided at a plurality of locations in the circumferential direction, the adjacent groove portions are arranged at intervals in the circumferential direction and overlap each other in the axial direction. By the fuel pressure, the pressure is substantially equalized over the entire circumferential direction of the axial end portion of the piston, and by this pressure equalizing action, it is possible to perform the aligning function with respect to the inner circumference of the piston.

  Moreover, in addition to the above configuration, an annular groove communicating with the groove portion is provided at the opposite end of the groove portion from the fuel chamber. Therefore, the groove portion and the annular groove can effectively perform the alignment function with respect to the inner circumference of the piston by the annular groove into which the fuel in the fuel chamber is always introduced through the groove portion.

The invention according to claim 5 is characterized in that the actuator is a piezoelectric actuator.

The case of applying to the apparatus according to claim 5 , wherein the member that generates the displacement is an actuator that generates a large force for driving and has a relatively excellent response, such as a piezo actuator using a piezo element. Even if it exists, the apparatus (fuel injection valve) which balances effectively the fuel leakage suppression from a 1st fuel chamber to a 2nd fuel chamber and the guarantee of a sliding characteristic in a piston can be obtained.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the component corresponding in each embodiment.

(First embodiment)
1 and 2 show a fuel injection valve according to the present embodiment. The fuel injection valve 1 of the present invention directly injects fuel into a cylinder of, for example, a diesel engine or an in-cylinder injection spark ignition internal combustion engine, and is distributed and supplied from a common rail as a pressure accumulating container common to each cylinder (not shown). High pressure fuel is injected. Note that the fuel injection valve according to the present embodiment can also be used for fuel injection other than in the cylinder, for example, into the intake port.

  As shown in FIG. 1, the fuel injection valve 1 is provided at a housing 2, an actuator 3 as a component of the fuel injection valve housed in the housing 2, a piston 10, and both axial ends 11 of the piston 10. A piston chamber 32 as a “first fuel chamber”, an intermediate chamber 31 as a “second fuel chamber”, a needle 50 as a “valve member” for opening and closing the injection hole 25, and a pressure control chamber 35 are provided.

  A substantially cylindrical sack portion 24 is formed at the distal end portion of the housing 1, and a plurality of injection holes 25 communicating with the sack portion 24 and penetrating the outer wall of the housing 1 are formed. Specifically, a plurality of injection holes 25 through which the sac portion 24 on the distal end side of the second inner periphery 22 and the outer wall of the housing pass are formed in the distal end portion.

  The second inner periphery 22 accommodates the needle 50 so as to be movable in the axial direction, and toward the upstream side of the fuel, the sac portion 24, the valve seat portion 23, the accommodation hole 22a, the guide hole 22b, and the sliding surface 22c. Is formed. The valve seat portion 23 is formed on, for example, a conical inner wall surface having an annular shape from the lower end of the accommodation hole 22a toward the inside, and the seat portion 51 of the needle 50 is seated and separated. The accommodation hole 22a is formed with a fuel gap (hereinafter referred to as a high pressure fuel gap passage) 42 through which high pressure fuel flows between the inner peripheral surface and the outer peripheral surface of the needle 50, and is equivalent to the fuel injection pressure (hereinafter referred to as the fuel injection pressure). A high pressure fuel passage 41 to which high pressure fuel (simply referred to as common rail pressure) is supplied is connected. The guide hole 22b enables the needle 50 to slide, and supports the guide portion 50c of the needle 50 so as to be slidable from the outside. The sliding surface 22c slidably supports the large-diameter base portion 50d of the needle 50, and forms a back pressure chamber 34 and a pressure control chamber 35 at both shaft end portions of the needle 50, respectively.

  The needle 50 includes a distal end portion 50a, a shaft portion 50b, a guide portion 50c, and a large diameter base portion 50d. The distal end portion 50a is formed in a substantially conical shape, and has a seat portion 51 that is seated on and separated from the valve seat portion 23. The seat portion 51 is seated on and separated from the valve seat portion 23, whereby the nozzle hole 25 is formed. Distribute and shut off the fuel to and from. The shaft portion 50b is substantially rod-shaped, and a high-pressure fuel gap 42 is formed between the shaft hole 50a and the high-pressure fuel passage together with the gap passage formed by separating the tip portion 50a and the valve seat portion 23. To do. The guide portion 50c is connected to the opposite end of the tip portion 50a in the shaft portion 50b, and is supported from the outside so as to be slidable in the guide hole 22b.

  The large-diameter base 50d is slidably disposed in the sliding hole 22c, and a back pressure chamber 34 and a pressure control chamber 35 are disposed at both shaft ends of the needle 50, respectively. The diameter of the large-diameter base portion 50d is formed to be larger than the tip portion 50a and the guide portion 50c on the tip side from the large-diameter base portion 50d, and the diameter of the guide portion 50b is formed to be larger than that of the tip portion 50a. However, the diameter of the guide portion 50b may be the same as that of the tip portion 50a.

  A needle spring 69 is provided in the back pressure chamber 34 at the shaft end of the needle 50 on the back pressure chamber 34 side, and the needle spring 69 biases the needle 50 in the valve closing direction.

  The first inner periphery 21 of the housing 2 accommodates the actuator 3, the spring 4, the piston 10, the intermediate chamber 31, and the piston chamber 32. The housing hole 21a, the guide hole 21b, and the piston chamber 32 are arranged toward the fuel downstream side. A sliding hole 21c is formed.

  In the housing hole 21a, the actuator 3 and the spring 4 are housed in an airtight manner, and an actuator chamber 5 is formed. The guide hole 21b is formed between both the accommodation hole 21a and the sliding hole 21c so as to be connected to both, and supports the small-diameter shaft portion 10b of the piston 10 from the outside in a movable manner.

  The sliding hole 21c slidably supports the large-diameter shaft portion 50a of the piston 50, and forms an intermediate chamber 31 and a piston chamber 32 at both shaft ends of the large-diameter shaft portion 50a of the piston 50, respectively. Is.

  The actuator 3 is, for example, a piezo actuator, and is formed by alternately stacking piezoelectric ceramic layers such as PZT and electrode layers. Lead wires are connected to the electrode layers, and the actuator 3 expands and contracts in the stacking direction (the axial direction in the figure) by charging and discharging with a drive circuit (not shown). In the actuator chamber 5, a spring 4 that urges the small-diameter shaft portion 10b of the piston 10 toward the actuator 3 is disposed.

  The back pressure chamber 34 and the pressure control chamber 35 are separated by a large-diameter base 50d of the needle 50. The back pressure chamber 34 is connected to the high pressure fuel passage 41 and is always in communication with the high pressure fuel passage 41, and the pressure control chamber 35. Is connected to the pressure-increasing fuel passage 43 and always communicates with the piston chamber 32 through the pressure-increasing fuel passage 43.

  The intermediate chamber 31 and the piston chamber 32 are separated by the large-diameter shaft portion 10 a of the piston 10, and the intermediate chamber 31 is connected to the high pressure fuel passage 41 and is always in communication with the high pressure fuel passage 41. The piston chamber 32 is connected to the pressure-increasing fuel passage 43 and is connected to the high-pressure fuel passage 41 through a check valve 60. The check valve 60 restricts fuel flow from the piston chamber 32 to the high-pressure fuel passage 41. The check valve 60 has a spherical valve body in the check valve chamber 33 that is always in communication with the piston chamber 32. When the internal pressure is higher than the pressure in the high-pressure fuel passage 41, that is, in a state where the pressure is increased, the communication between the piston chamber 32 and the high-pressure fuel passage 41 is stopped.

  The pressure in the pressure control chamber 35 acts as a pressing force that acts on the needle 50 in the valve opening direction. When the actuator 3 is extended by applying a voltage when the actuator 3 is energized, the piston 10 moves downward in the axial direction in the figure. In the piston chamber 32, the fuel volume in the piston chamber 32 is reduced (decreased) by the downward movement of the piston 10 in the axial direction in the drawing. Such a piston 50 increases the fuel pressure in the piston chamber 32, the pressure-increasing fuel passage 43, and the pressure control chamber 35 while closing the check valve 60 in the piston chamber 32.

  An acting force (hereinafter referred to as a first valve opening direction force) due to the fuel pressure in the pressure control chamber 35 and a fuel pressure in the high pressure fuel gap passage 42 act on the needle 50 in the valve opening direction of the needle 50. The valve opening direction acting force based on the sum of the acting forces (hereinafter referred to as the second valve opening direction force), the action force due to the fuel pressure in the back pressure chamber 34 (hereinafter referred to as the first valve closing direction force), and the action by the needle spring 69. A valve closing direction acting force based on the sum of forces (hereinafter referred to as second valve closing direction force) acts.

  When the actuator 3 is energized, the fuel pressure in the pressure control chamber 35 is increased from the common rail pressure by such a pressure increasing action, the first valve opening direction force is increased, and the valve opening direction acting force becomes the valve closing direction acting force. When it becomes larger, the needle 50 is pushed upward in the axial direction in the drawing (hereinafter referred to as “lifting”), and the seat portion 51 of the needle 50 is separated from the valve seat portion 23. When the seat portion 51 is separated from the valve seat portion 23, the high-pressure fuel passage 41 communicates with the injection hole 25 and fuel injection is started from the injection hole 25.

  On the other hand, when the energization of the actuator 3 is stopped, the actuator 3 contracts and the piston 10 is returned upward in the axial direction in the drawing by the action of the spring 4. Such movement of the piston 10 increases the fuel volume of the piston chamber 32. As a result, the fuel pressure in the piston chamber 32 and the pressure control chamber 35 decreases, but due to the action of the check valve 60 installed in the piston chamber 32, the fuel pressure in the piston chamber 32 and the pressure control chamber 35 is high. It does not drop below the common rail pressure in the fuel passage 41.

  When the first valve opening direction force decreases and the valve opening direction acting force becomes smaller than the valve closing direction acting force when the actuator 3 is deenergized, the seat portion 51 is seated from the valve seat portion 23, and from the injection hole 25. Fuel injection is stopped.

  The basic configuration of the fuel injection valve 1 has been described above. Hereinafter, a characteristic configuration of the fuel injection valve 1 will be described.

(Characteristic configuration)
As shown in FIGS. 1 and 2, the large-diameter shaft portion 10 a of the piston 10 includes an axial end portion 11 and a body portion 14 that integrally connects the axial end portions 11. The end 11 and the main body 14 each have a sliding end 12 and a sliding main body 15 that slide with respect to the sliding hole 21c. The sliding end portion 12 and the sliding main body portion 15 correspond to the sliding portion described in the claims.

  As shown in FIG. 2, the sliding end portion 12 and the sliding main body portion 15 are arranged with a predetermined gap (hereinafter referred to as sliding clearance) δ with respect to the sliding hole 21c. Since the fuel pressure in the piston chamber 32 is maintained at a fuel pressure equal to or higher than the common rail pressure in the intermediate chamber 31, the fuel entering the sliding clearance δ flows from the axial end 11 on the piston chamber 32 side, and the intermediate chamber It flows out to the 31 side.

  As shown in FIG. 2, the sliding end portion 12 of the axial end portion 11 is provided with a groove portion 13 a inclined in the axial direction, and a plurality of groove portions 13 a are provided along the circumferential direction of the sliding end portion 12. It is arranged at the place. The groove portion 13 a extends in the inclined direction of the inclined groove portion 13 a (hereinafter simply referred to as “extending direction”), and the opening portion in the extending direction of the groove portion 13 a is in the fuel chambers 31 and 32 in contact with the axial end portion 11. Communicate.

  Here, the first inner periphery 21 and the second inner periphery 22 correspond to the inner periphery described in the claims.

  In the embodiment of the present invention, the piston 10 slides on the first inner periphery 21 of the housing 2 in order to increase or decrease the pressure in the pressure control chamber 35 in response to the displacement of the actuator 3. The sliding end portion 12 slidably supported by the first inner periphery 21, that is, the sliding hole 21 c at the axial end portion 10, is inclined in the axial direction and extends in the inclined direction. A groove portion 13a communicating with the fuel chambers 31 and 32 in contact with the end portion 11 is provided and provided at a plurality of locations in the circumferential direction (hereinafter referred to as a first configuration).

  With such a configuration, fuel for forming an oil film is always supplied from the fuel chambers 31 and 32 to the grooves 13a provided at a plurality of locations in the circumferential direction. Therefore, no matter what the sliding state of the piston 10 (for example, the sliding state by quick piston movement), the fuel for forming the oil film is formed in the groove portion 13a formed in the sliding end portion 12 of the piston 10. It is supplied without interruption and is always maintained.

Further, the adjacent groove portions 13a in the circumferential direction are arranged at intervals in the circumferential direction, and there are portions L (hereinafter referred to as wrap portions) L that overlap each other in the axial direction. In other words, in the present embodiment, in addition to the first configuration, the adjacent groove portions 13a are arranged at intervals in the circumferential direction at the sliding end portion 12 and are also mutually overlapped in the axial direction. Since it is configured to overlap with L (hereinafter referred to as the second configuration), the fuel that is always held in the adjacent groove portions 13a as described above is divided into sliding sections that are sandwiched between the groove portions 13a during the sliding movement of the piston 10. It can be derived from both the axial direction and the circumferential direction.

  With the first and second configurations described above, in the piston 10, fuel leakage from the piston chamber 32 to the intermediate chamber 31 with respect to the sliding hole 21c is suppressed, and between the sliding portions 12 and 15 of the piston 10 and the sliding hole 21c. It is possible to obtain a fuel injection valve that achieves both the sliding characteristic guarantee at the same time.

  In addition, the inventor verified that the sliding characteristics were not impaired by the experiment shown in FIG. FIG. 3B shows a test apparatus for evaluating the sliding characteristics. The sliding frictional force shown in the characteristic diagram of FIG. 3A is obtained by using the pseudo piston 110 and the pseudo housing 102 simulating the piston 10 and the housing 2. P (hereinafter simply referred to as “sliding force”) P and load load (hereinafter referred to as load) F were measured. Lubricating oil corresponding to fuel was applied to the sliding portion of the pseudo piston 110 and the inner periphery of the pseudo housing 102, and the pseudo piston 110 was inserted into the pseudo housing 102. In the piston 10, a load F is applied in a direction perpendicular to the axial direction with respect to the small diameter end portion 10b, and a measuring instrument that measures the sliding force P in the figure with the load value F when the load F is changed as a parameter is used. The sliding force P corresponding to the load value F is measured. According to this, as shown by the characteristic of the solid line in FIG. 3A, the apparatus according to the embodiment of the present invention has any sliding condition (the load F is a parameter) as compared with the apparatus according to the prior art. The sliding force P of the piston 10 can be reduced, and the target (desired sliding characteristics can be guaranteed).

According to the first and second configurations, the following effects can be obtained. In other words, while the groove portions 13a are provided at a plurality of locations in the circumferential direction, the adjacent groove portions 13a are arranged at intervals in the circumferential direction and overlap each other in the axial direction. In other words, any of the groove portions 13a is arranged over the entire circumference in the circumferential direction. Therefore, the fuel pressure of the fuel held in the groove portion 13a substantially equalizes the pressure around the entire circumferential direction of the axial end portion 11 of the large-diameter shaft portion 10a of the piston 10, and as a result, the pressure-sliding action of the piston 10 occurs. It is possible to fulfill the alignment function for the moving hole 21c.

  Although the first and second configurations can perform the alignment function for the sliding hole 21c of the piston 10, it is preferable to further have the following configuration. That is, the sliding end portion 12 is provided with an annular groove (hereinafter referred to as a pressure equalizing groove) 13b that is annularly adjacent to the groove portion 13a in the axial direction. Specifically, as shown in FIG. 2, the groove 13a has an opening opposite to the opening connected to the pressure equalizing groove 13b, and the groove 13a is always in communication with the pressure equalizing groove 13b. According to this, the groove 13a and the pressure equalizing groove 13b are effective in aligning the sliding hole 21c of the piston 10 with the pressure equalizing groove 13b in which the fuel in the fuel chambers 31 and 32 is always introduced through the groove 13a. Can be fulfilled.

  In the present embodiment described above, the groove portion 13a is provided in both the axial end portions 11 of the large diameter shaft portion 10a of the piston 10, but the both axial end portions 11 of the large diameter shaft portion 10a are provided. A configuration may be adopted in which the groove portion 13a is provided limited to the end portion 11 in the specific axial direction.

  For example, the same effect can be obtained even when the groove 13a is provided only in the axial end 11 on the piston chamber 32 side. In this case, in addition to the configuration in which the small-diameter shaft portion 10b and the large-diameter shaft portion 10a are integrally formed in the piston 10 described above, the small-diameter shaft portion 10b is slidably supported by the support hole 21b. And Such a large-diameter shaft portion 10a has an axial end portion 11 on the piston chamber 32 side that may be pressed against the sliding hole 21c even if the piston 10 is inclined within the range of the sliding clearance δ. The groove portion 13a is surely provided. Therefore, by providing the groove 13a only at the specific axial end of the both axial ends 11, the fuel injection valve that achieves both the above-described fuel leakage suppression and sliding characteristic guarantee while improving productivity. Can be provided.

  In the present embodiment described above, the actuator 3 is a piezo actuator. According to this, as a member for generating displacement, a fuel mainly composed of the fuel injection valve 1 is an actuator having a large driving force and relatively excellent response, such as a piezo actuator using a piezo element. It is used for an injection device (hereinafter simply referred to as “device”). Even when applied to such a device, a device that effectively achieves both fuel leakage suppression between the fuel chambers 31 and 32 and guarantee of sliding characteristics in the piston 10 can be obtained.

(Second Embodiment)
A second embodiment is shown in FIG. The second embodiment is a modification of the first embodiment. In the second embodiment, an example is shown in which a plurality of groove portions are formed in a spiral groove 113a that integrally connects them.

  As shown in FIG. 4, the spiral groove 113 a in the sliding end portion 12 is configured to integrally connect all of the plurality of groove portions described in the first embodiment and to have a spiral shape.

  Even if it is such a structure, the effect similar to 1st Embodiment can be acquired.

  In addition, according to such a configuration, since all of the plurality of groove portions are formed in the spiral spiral groove 113a, the plurality of groove portions are individually formed at any location in the circumferential direction. There is no need to do. Therefore, it is possible to reliably provide a fuel injection valve having excellent productivity.

(Third embodiment)
A third embodiment is shown in FIG. The third embodiment is a modification of the third embodiment. In 3rd Embodiment, an example which makes the groove part of a specific group the spiral groove | channels 213a and 313a which connect integrally among several groove parts is shown.

  As shown in FIG. 5, the spiral grooves 213a and 313a divide the plurality of groove portions into a specific first group groove portion and a specific second group groove portion, and correspond to the first group groove portions, The spiral groove 213a is integrated with the groove portion, and the spiral groove 313a is integrated with the groove portion corresponding to the groove portion of the second group.

  Even if it is such a structure, the effect similar to 1st Embodiment can be acquired.

  Furthermore, in a specific group of groove portions, the extending range extending in the inclination direction of the groove portions, in other words, the circumferential range in which the groove portions are formed is limited, which is superior to a forming method in which a plurality of such groove portions are formed. A fuel injection valve having high productivity can be obtained.

  Further, since the plurality of groove portions are not all connected integrally, it is easy to enlarge the total opening area of the opening portions of the spiral grooves 213a and 313a communicating with the fuel chambers 31 and 32. . For example, even when the cross-sectional areas of the openings of the spiral grooves 213a and 313a are kept small, the necessary opening area can be ensured by the total opening area of the openings of the spiral grooves 213a and 313a.

  In FIG. 5, the openings of the spiral grooves 213a and 313a are semicircular and triangular (V-shaped) for convenience of explanation, but they are semicircular, triangular or rectangular. It may be either. Moreover, it is good also considering the shape of each opening part of the spiral grooves 213a and 313a as the same shape.

  In the present embodiment described above, a plurality of groove portions are divided into any specific group and attached to each specific group to form a spiral groove. However, any one of the specific groups is formed as a spiral groove. It is good also as a structure formed in.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, this invention is limited to this embodiment and is not interpreted and can be applied to various embodiment in the range which does not deviate from the summary.

  (1) In the present embodiment described above, the piston 10 is configured such that the small diameter shaft portion 10b and the large diameter shaft portion 10a are integrally formed. However, the present invention is not limited to this, and the small-diameter shaft portion and the large-diameter shaft portion may be separated, and the small-diameter shaft portion may be configured to contact the large-diameter shaft portion. In this case, it is set as the structure which provides the said groove part 13a in both the axial direction both ends of the large diameter shaft part of a piston.

  According to such a configuration, the small-diameter shaft portion abuts at any position of the large-diameter shaft portion, and as a result, the sliding end portions of both ends in the axial direction of the large-diameter shaft portion slide between the sliding holes. Even if there is an inclination in the range of the dynamic clearance δ and both sliding end portions are pressed against the sliding hole, the sliding force F is suppressed by the groove portion 13a, so that the sliding characteristics can be easily guaranteed. It becomes like this.

  (2) In the present embodiment described above, the shape of the opening of the groove 13a is semicircular or triangular (V-shaped), but any opening shape such as semicircular, triangular, or rectangular may be used. There may be.

  (3) In the present embodiment described above, the groove portion 13 a and the pressure equalizing groove 13 b are provided in the sliding end portion 12, but the groove portion 13 a may be provided in the sliding end portion 12.

It is sectional drawing which shows the fuel injection valve by 1st Embodiment of this invention. It is an enlarged view which shows the characteristic structure of the piston in FIG. FIG. 3 is a diagram in which the sliding frictional force on the inner periphery of the piston and the housing in FIG. 1 is simulated, FIG. 3A is a characteristic diagram showing the sliding frictional force with respect to a load load, and FIG. It is a schematic diagram explaining the measurement conditions which measured the load load and sliding frictional force in (a). It is an enlarged view which shows the piston concerning the fuel injection valve by 2nd Embodiment. It is an enlarged view which shows the piston concerning the fuel injection valve by 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Housing 21 1st inner periphery (inner periphery)
21a accommodation hole 21b support hole 21c sliding hole 22 2nd inner periphery (inner periphery)
22a Housing hole 22b Guide hole 22c Sliding surface 23 Valve seat part 24 Suck part 25 Injection hole 3 Piezo actuator (actuator)
4 Spring 5 Actuator chamber 10 Piston 10a Large diameter shaft portion 10b Small diameter shaft portion 11 Axial end portion 12 Sliding end portion 13a Inclined groove portion (groove portion)
13b Pressure equalizing groove (annular groove)
14 Body 15 Sliding Body 31 Intermediate Chamber (Second Fuel Chamber)
32 Piston chamber (first fuel chamber)
33 Check valve chamber 34 Back pressure chamber 35 Pressure control chamber 41 High pressure fuel passage 42 High pressure fuel gap passage 43 Pressure increase fuel passage 50 Needle (valve member)
50a Tip 51 Seat 50b Shaft 50c Guide 50d Large diameter base 60 Check valve 69 Needle spring

Claims (5)

A valve member for opening and closing the nozzle hole;
A pressure control chamber that applies a pressure in the valve opening direction to the shaft end of the valve member on the side opposite to the injection hole;
A high-pressure fuel passage for supplying fuel injected from the nozzle hole to the nozzle hole,
A fuel injection valve for injecting fuel by increasing the pressure in the pressure control chamber above the fuel pressure in the high-pressure fuel passage;
An actuator that generates displacement when energized;
A piston that transmits the displacement of the actuator via hydraulic pressure and increases or decreases the pressure in the pressure control chamber;
A housing that accommodates the actuator, the piston, and at least the shaft end portion of the valve member on the side opposite to the injection hole;
Have
The piston is slidably supported on the inner periphery of the housing,
One axial end of the two axial ends of the piston is formed by the one axial end and the inner periphery of the housing, and a first fuel chamber communicating with the pressure control chamber is provided. A second fuel chamber formed by the other axial end portion and the inner periphery of the housing is provided, wherein the other axial end portion cooperates with the actuator.
At least the specific axial direction end of the both axial ends is a sliding portion that slides on the inner periphery,
Grooves formed at a plurality of locations in the circumferential direction of the sliding portion, and are inclined in the axial direction and extend in the inclined direction, and the specific axial end of the first fuel chamber and the second fuel chamber A groove communicating with the specific fuel chamber in contact with the section,
Adjacent grooves extending in the inclined direction are arranged at intervals in the circumferential direction and overlap each other in the axial direction ,
An inner periphery of the housing has a sliding hole that slidably supports the sliding portion of the piston and divides the first fuel chamber and the second fuel chamber, and cooperates with the actuator. The piston includes a large-diameter shaft portion supported by the sliding hole, and a small-diameter shaft portion having a smaller diameter than the large-diameter shaft portion, and a small-diameter shaft portion that is integrally linked to the actuator,
The small-diameter shaft portion is configured to be able to contact the large-diameter shaft portion,
The fuel injection valve according to claim 1, wherein the large-diameter shaft portion is formed with the groove portion in the sliding portion at both axial end portions .   2. The fuel injection valve according to claim 1, wherein among the plurality of groove portions, a specific group of groove portions are integrally connected to each other to form a spiral groove.   The fuel injection valve according to claim 1 or 2, wherein all of the plurality of grooves are integrally connected. The sliding portion is
4. The annular groove having an annular shape and communicating with the groove portion is provided at an end opposite to the specific fuel chamber in the groove portion. 5. Fuel injection valve. The fuel injection valve according to any one of claims 1 to 4, wherein the actuator is a piezo actuator .

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