JP2006105260A - Spring member, piezo driving device, and piezo type injector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spring member with a wide load range and a hardly wearing abutting part by modifying a spring member shape applying an initial load to a piezo element in a piezo driving device used in a piezo type injector. <P>SOLUTION: The spring member 31 comprises an annular plate spring, and since a radial cross sectional shape of a plate face is substantially V-shaped, spring force is larger than a disc spring which can be installed in the same space. In the piezo driving device of the piezo type injector, wear can be prevented since there is no relative displacement between abutting parts of a V-shaped middle part 313 of the spring member 31, and a first piston and a plate member when a preset spring of combining two spring members 31 is arranged between the first piston displaced integrally with a piezo stack, and the plate member arranged in a lower end of a vertical hole. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezo drive device used for a piezo injector or the like, and more particularly to a shape of a spring member used for applying an initial load to a piezo element in the piezo drive device or for another load loading mechanism.

  In a fuel injection device such as a diesel engine, a piezo-type injector provided with a piezo drive device is known, and high fuel injection control is expected because of its good response. The piezo drive device usually has a piezo element that generates a displacement by energization and a piston member for transmitting the displacement of the piezo element, and increases or decreases the pressure in the hydraulic chamber as the piston member reciprocates. ing. Combustion injection can be controlled by driving the nozzle needle by the pressure in the hydraulic chamber or via a hydraulic control valve.

As a prior art, there is Patent Document 1, which discloses an injector actuator in which a piston is arranged on one end side of a piezo element, and the piston is operated by the piezo element to change the oil pressure in a cylinder chamber defined by the piston. .
Japanese Patent Publication No. 7-94812

  FIG. 9A is a diagram illustrating an example of a piezo drive device. The displacement of the piezo stack (piezo element) 101 is transferred via a hydraulic transmission device including a first piston 102, a second piston 103, and an oil-tight chamber 104. It is configured to communicate. In this configuration, when the piezo stack 101 is extended by energization, the first piston 102 is displaced integrally, and the pressure in the oil tight chamber 104 is increased. Accordingly, when the second piston 103 opens a hydraulic control valve (not shown), the back pressure of the nozzle needle is reduced, the nozzle needle is lifted, and combustion is injected.

  Here, when the piezo stack 101 is used, a compression force is generally applied for the purpose of preventing breakage. For example, in the piezo drive device shown in FIG. 9A, a disc spring 105 is installed between the first piston 102 and the plate member 106 disposed below the first piston 102 to apply a predetermined initial load to the piezo stack 101. ing. That is, as shown in FIG. 9B, the conventional disc spring 105 is formed between a movable member (first piston 102 in FIG. 9A) and a fixed member (plate member 106 in FIG. 9A). And is used in such a manner that both members are loaded. However, the load is relatively small, and there is a risk that the load cannot be sufficiently met when the required spring force is large. Further, when one of the members is a movable member, there is a problem in that relative sliding occurs at the contact portion between the disc spring 105 and both members due to the displacement, and wears.

  As shown in FIG. 10, a configuration in which a plurality of disc springs are arranged in series is also known, but the spring force is small, and wear of the contact portion is inevitable.

  On the other hand, Patent Document 1 proposes to use a hollow cylindrical spring for biasing the piezoelectric element instead of the biased load acting on the piezoelectric element by a compression spring such as a disc spring. is doing. This hollow cylindrical spring is a metal cylinder that is provided with spring elasticity by forming a spiral slit in the middle of the cylinder wall, and is inserted around the piezoelectric element. The element is supported.

  However, in the configuration of Patent Document 1, the shape of the hollow cylindrical spring for energizing the piezoelectric element is complicated, and in order to obtain desired spring characteristics, it is necessary to form many slits in the cylindrical wall with high accuracy, and it takes time to manufacture. And costly. In addition, there is a problem that the size of the piezo element in the expansion / contraction direction (the axial direction of the injector) is increased, and a large mounting space is required.

  Therefore, in view of these problems, the present invention has reviewed the shape of a spring that applies a load to a member such as a piezo element, and obtains a spring member that has a large load range that can be applied and that has a simple configuration and a small mounting space. 1 purpose. A second object is to suppress the occurrence of wear at the contact portion between the spring member and the adjacent member with the displacement of the movable member. By using such a spring member, it is intended to realize a piezo drive device and a piezo injector that are small in size and easy to manufacture, and have both high performance and high reliability.

  A first aspect of the present invention is a spring member used in a load loading mechanism, wherein one end side is supported by a movable member and the other end side is supported by a fixed member, and a predetermined load is loaded through the movable member. This spring member is composed of an annular leaf spring, and the inner ring portion and the outer ring portion are warped in the same direction, and an intermediate ring projecting in a direction opposite to the warp direction between the inner ring portion and the outer ring portion. The shape has a part.

  In the above configuration, when a load is applied to the spring member, the half on the inner peripheral side tends to spread outward while the half on the outer peripheral side tends to shrink inward. For this reason, unlike the conventional disc spring, it cannot be freely deformed, and a large repulsive force is generated. Therefore, the spring force can be increased without increasing the size of the spring. This spring force can be adjusted by the plate thickness, and a desired spring force according to the demand can be realized. Further, since forces in opposite directions are applied from the inner peripheral side and the outer peripheral side, relative displacement does not occur between the intermediate annular portion and the member in contact with the intermediate annular portion, and wear can be prevented. Thus, it is possible to obtain a spring member that has a simple configuration, has a large load range applied to the member, and is less likely to be worn. The spring member can be easily formed by pressing and has a small size in the expansion / contraction direction, and can be mounted in a small space.

  Specifically, the annular leaf spring serving as the spring member can be configured such that the radial cross-sectional shape of the plate surface is substantially V-shaped. By making it substantially V-shaped, it is possible to easily realize a spring shape in which the inner annular portion and the outer annular portion warp in the same direction and the intermediate annular portion projects in the opposite direction, and the above-described effects can be obtained.

  As in the invention of claim 3, the annular leaf spring constituting the spring member can be easily formed by press-molding one annular flat plate.

  As in the invention of claim 4, in the annular leaf spring, if the plate thickness of the intermediate annular portion is larger than the plate thickness of the inner annular portion and the outer annular portion, the spring force can be increased, and the inner and outer circumferences can be increased. Since the portion is thin, the manufacturing process can be made relatively easy. Furthermore, by increasing the plate thickness of the intermediate annular portion where stress during loading is concentrated, the maximum stress is reduced and the stress distribution is made uniform and the reliability is improved.

As in the invention of claim 5, when the maximum plate thickness of the annular leaf spring is Tmax, the inner diameter is Din, and the outer diameter is Dout, the following formula (1)
Tmax ≦ (Dout−Din) / 4 (1)
If the configuration satisfies the above, it is possible to facilitate processing by making the plate thickness shorter than the length of the flat portion at the time of bending.

  As in the sixth aspect of the present invention, the spring member may be a composite spring in which a plurality of annular leaf springs are combined. In this case, at least two of the plurality of annular leaf springs may be arranged so that the inner circumferential annular portion and the outer circumferential annular portion are in contact with each other.

  For example, when two annular leaf springs are disposed between the movable member and the fixed member so that the inner peripheral annular portion and the outer peripheral annular portion are in contact with each other, the two members and the spring member are intermediate annular portions. Therefore, no relative displacement occurs, and no wear occurs between the two members.

  According to a seventh aspect of the present invention, there is provided a piezo drive device using the spring member according to any one of the first to sixth aspects, wherein the annular member is interposed between a movable member and a fixed member that are displaced following the piezo element. A leaf spring is provided, and a preload is applied to the piezo element by the annular leaf spring.

  As described above, by using the spring member having a small mounting space and a large load range for the piezo drive device, a desired initial load can be applied to the piezo element with a simple configuration, and the occurrence of wear can be suppressed. Therefore, it is possible to realize a piezoelectric drive device that is small and easy to manufacture, and that has high performance and high reliability. In addition, since a load is applied via the movable member, it is possible to suppress an uneven load from being applied to the piezo element. By using the fixed member as a height adjustment member when the spring member is assembled, setting of an initial load, etc. Becomes easier.

  The invention of claim 8 is a piezo-type injector using the piezo drive device according to claim 7, comprising a control valve driven by the piezo drive device and a control chamber for applying pressure in the valve closing direction to the nozzle needle. The fuel injection is controlled by increasing or decreasing the pressure in the control chamber by opening and closing the control chamber and the low pressure passage with a control valve.

  By using the high-performance and high-reliability piezoelectric drive device of the present invention for the drive unit, fuel injection of the injector can be performed with good controllability. Furthermore, the overall length of the piezo injector (piezo element stacking direction) can be reduced, and the mounting property on the vehicle is improved.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are views showing the configuration of the spring member 31 in the first embodiment, and FIG. 4 is a view showing the configuration of a piezo injector using the piezo drive device 1 incorporating the spring member 31 as a drive unit. Here, it demonstrates as an example applied to the common rail type fuel injection device of a diesel engine. Piezo-type injectors are provided corresponding to each cylinder of the engine (only one of them is shown in FIG. 4), and is supplied with fuel (light oil here) from a common rail (not shown). In the common rail, fuel pumped by a high-pressure supply pump (not shown) is stored at a predetermined high pressure corresponding to the injection pressure.

  First, the overall configuration of the piezoelectric injector will be described with reference to FIG. In the drawing, the piezo injector has a nozzle body H4 disposed at the lower end of a housing H1 in which the piezo drive device 1 is accommodated via valve bodies H2 and H3, and is oil-tightly fixed by a retainer H5. A high-pressure fuel passage 62 is formed in the housing H1 in the vertical direction, and communicates with an external common rail (not shown) via a fuel introduction pipe 63 protruding from the upper side. A fuel outlet pipe 65 communicating with the low pressure fuel passage 64 protrudes from the upper portion of the housing H1, and the fuel flowing out from the fuel outlet pipe 65 is returned to the fuel tank (not shown).

  The housing H1 is substantially cylindrical, and houses the piezo drive device 1 in a vertical hole 61 that is eccentric with respect to the central axis. The vertical hole 61 is provided in parallel to the side of the high-pressure fuel passage 62, and the low-pressure fuel passage 64 extends further downward via a gap between the vertical hole 61 and the piezo drive device 1. The piezo drive device 1 transmits the driving force of the piezo stack 2 that is a piezo element by a hydraulic transmission device including first and second pistons 41 and 43 and an oil-tight chamber 42 and is driven to the control valve 5 having a three-way valve structure. It is supposed to be.

  When the valve body 51 selectively closes the high pressure passage 52 or the low pressure passage 54, the control valve 5 allows the back pressure chamber 46 of the nozzle needle 45 to be connected to the high pressure passage 52 or the low pressure passage 54 via a communication passage (not shown). The back pressure of the nozzle needle 45 is increased or decreased by selectively communicating. The high pressure passage 52 communicates with the high pressure fuel passage 62 and the low pressure passage 54 communicates with the low pressure fuel passage 64. A spring 53 is disposed below the valve body 51 to urge the valve body 51 upward.

  The valve body 51 is at an upper end position that closes the low-pressure passage 54 in a state where the piezo drive device 1 is not operated, and the high-pressure passage 52 is opened and high-pressure fuel flows into the back pressure chamber 46. At this time, the nozzle needle 45 is in the lower end position by the pressure of the back pressure chamber 46, and fuel injection is not performed. When the piezo drive device 1 is actuated to push the valve body 51 down to the lower end position, the communication between the back pressure chamber 46 and the high pressure passage 52 is cut off, and the low pressure passage 54 is opened. Then, the pressure in the back pressure chamber 46 decreases, the nozzle needle 45 rises, and fuel is injected from the nozzle hole 47.

  The piezo stack 2 as a piezo element has a known configuration in which piezoelectric ceramic layers such as PZT and electrode layers are alternately stacked, and is housed in the cylindrical casing 11 with the stacking direction (vertical direction in the figure) as the expansion / contraction direction. Electrode lead rods 2 a and 2 b are connected to the piezo stack 2, and are charged and discharged by a drive circuit (not shown) via a connector 12 mounted above the cylindrical casing 11. In the casing 11, a rod 13 that moves up and down integrally with the lower end surface of the piezo stack 2 is accommodated. ing.

  The lower end edge of the bellows 15 is welded and fixed to the outer periphery of the disk-shaped member 14 constituting the bottom surface of the casing 11, and the upper surface of the disk-shaped member 14 is in contact with the lower end surface of the rod 13. Thereby, the disk-shaped member 14 can transmit the displacement of the piezo stack 2 to the first piston 41 located below the casing 11. The bellows 15 expands and contracts in the vertical direction following the displacement of the piezo stack 2 and enables the disc-like member 14 to be displaced. A preload in the compression direction is applied to the piezo stack 2 together with a preset spring 3 described later.

  The first piston 41 as a movable member constituting the hydraulic transmission device is slidably provided in the lower end portion of the vertical hole 61 so as to slide up and down following the displacement of the piezo stack 2. . The first piston 41 has a cylindrical shape with an upper end closed, and a second piston 43 is slidably provided in the cylindrical portion. The lower half portion of the small diameter of the second piston 43 protrudes downward from the cylindrical portion of the first piston 41, and the pin-shaped tip portion is in contact with the valve body 51 of the control valve 5. A space surrounded by the upper inner wall surface of the first piston 41 and the upper end surface of the second piston 43 is filled with fuel as hydraulic oil to form an oil tight chamber 42.

  The oil-tight chamber 42 converts the displacement of the first piston 41 into hydraulic pressure and transmits it to the second piston 43. Since piezoelectric ceramics such as PZT are different from metals in the amount of thermal deformation, it is preferable to use a displacement transmission device using hydraulic pressure in this way as a means for mixing both. Thereby, the amount of thermal deformation which differs between members can be absorbed and good transmission performance can be maintained. Moreover, when it is set as the structure which accommodates the 2nd piston 43 in the 1st piston 41 like this embodiment, the axial direction length of the piezo drive device 1 can be shortened.

  A check valve 44 is provided between the first piston 41 and the disc-like member 14 by providing a ball valve in a passage communicating between the oil-tight chamber 42 and the vertical hole 61. The check valve 44 allows only hydraulic oil to flow in the direction of the oil-tight chamber 42 and replenishes the oil-tight chamber 42 from the low-pressure fuel passage 64 when the pressure of the oil-tight chamber 42 decreases due to a fuel leak or the like. The lower end surface of the disk-shaped member 14 is formed into a concave curved surface shape, and the upper end surface of the check valve 44 constituting member that is in contact therewith is formed into a convex curved surface shape. In this way, automatic alignment is possible by making contact with the uneven curved surface.

  As shown in FIG. 5A, in the lower end portion of the vertical hole 61, a plate member 16 serving as a fixing member is placed on the upper surface of the valve body H2, and between this plate member 16 and the lower end surface of the first piston 41. Further, a preset spring 3 is disposed. The plate member 16 and the preset spring 3 are ring-shaped and are arranged on the outer periphery of the lower half of the small diameter of the second piston. As shown in FIG. 5B, in the present embodiment, the preset spring 3 is composed of a composite spring in which two spring members 31 are stacked in the vertical direction. The shape of the spring member 31 is a characteristic part of the present invention and will be described in detail below.

  1A is a perspective view showing the overall configuration of the spring member 31, and FIG. 1B is a perspective view showing the cross-sectional shape thereof. As shown in the drawing, the spring member 31 is formed of an annular leaf spring. The surface has a shape in which an intermediate portion in the radial direction is recessed in a substantially V shape downward in the drawing. Specifically, as shown in FIG. 2, an inner peripheral annular portion (hereinafter referred to as an inner peripheral portion) 311 and an outer peripheral annular portion (hereinafter referred to as an outer peripheral portion) 312 are warped in a substantially bow shape in the same direction (upward in the drawing) An annular portion (hereinafter referred to as an intermediate portion) 313 projects in a direction opposite to the warping direction of the inner and outer peripheral portions 311 and 312 (downward in the drawing).

  In FIG. 2, when a load F acts on the spring member 31, the spring member 31 tends to spread outward from the inner peripheral portion 311 to the intermediate portion 313, while trying to shrink inward from the outer peripheral portion 312 to the intermediate portion 313. . For this reason, the deformation of the spring member 31 is not free like a conventional disc spring, and a large repulsive force is generated. Therefore, a spring having a large spring force can be obtained as compared with a disc spring that can be installed in the same space.

  The spring member 31 having such a shape can be obtained, for example, by press-molding an annular flat plate made of spring steel. The spring force can be adjusted by changing the plate thickness. For example, the spring force is reduced by reducing the plate thickness. Therefore, a spring member that can be arbitrarily adjusted from a small spring force to a large spring force and has a large load load range can be realized.

Here, as shown in FIG. 3, when the maximum leaf thickness is Tmax, the inner diameter is Din, and the outer diameter is Dout, the annular leaf spring constituting the spring member 31 is expressed by the following formula (1).
Tmax ≦ (Dout−Din) / 4 (1)
It is better to have a shape that satisfies With this configuration, the plate thickness is shorter than the length of the flat portion at the time of bending, so that processing into a substantially V shape can be facilitated.

  At this time, as shown in FIG. 3, the intermediate portion 313 may be thicker than other portions, and the inner peripheral portion 311 or the outer peripheral portion 312 side may be thinned. With this configuration, even when the plate thickness is increased in order to increase the spring force, the inner peripheral portion 311 and the outer peripheral portion 312 are thin, so that molding is facilitated. Furthermore, by increasing the plate thickness of the intermediate annular portion where stress during loading is concentrated, the maximum stress is reduced and the stress distribution is made uniform and the reliability is improved.

  When a plurality of such spring members 31 are combined to form the preset spring 3, the inner peripheral portion 311 and the inner peripheral portion 311 and the outer peripheral portion 312 and the outer peripheral portion 312 are in contact with each other as shown in FIG. In this state, it is incorporated into the piezo drive device 1 shown in FIG. At this time, the intermediate portion 313 of the upper spring member 31 contacts the first piston 41 that is a movable member, and the intermediate portion 313 of the lower spring member 31 contacts the plate member 16 that is a fixed member. As described above, when the preset spring 3 is positioned at the lower end of the piezo drive device 1, it is easy to assemble, and the set load can be easily adjusted by using the plate member 16 as a height adjusting member.

  As a result, an upward load is applied to the lower end surface of the first piston 41 that is a movable member, and the first piston 41 is pressed against the disk-shaped member 14 so as to be integrally displaceable. Furthermore, it acts on the piezo stack 2 via the disk-shaped member 14 and the rod 13, and becomes a compressive force of the piezo stack 2. Therefore, these urging forces may be set so that the sum of the compression force of the preset spring 3 and the compression force applied by the bellows 15 becomes a predetermined preload required for the piezo stack 2. Further, the biasing force of the preset spring 3 increases the contact pressure between the members that transmit the displacement, and suppresses a loss when the displacement of the piezo stack 2 is transmitted to the first piston 41 to a minimum.

  Next, the operation of the piezoelectric injector having the above configuration will be described. In a state where the piezo stack 2 of the piezo drive device 1 is contracted in a discharged state, the valve body 51 of the control valve 5 is urged upward by a spring 53 to close the low pressure passage 54 and communicate with the high pressure passage 52. Due to the pressure in the pressure chamber 46, the nozzle needle 5 is in the lower end position for closing the nozzle hole.

  From this state, when the piezo stack 2 is energized and extended, the disk-shaped member 14 that is displaced integrally with the piezo stack 2 pushes down the first piston 41. When the first piston 41 descends while compressing the preset spring 3, the hydraulic oil (light oil here) in the oil-tight chamber 42 is compressed accordingly. When the pressure of the hydraulic oil lowers the second piston 43 and pushes down the valve body 51 of the control valve 5, the low pressure passage 54 is opened and the high pressure passage 52 is closed. As a result, when the pressure in the back pressure chamber 46 communicating with the low pressure passage 54 decreases and the nozzle needle 45 is lifted, fuel is injected from the nozzle hole 47.

  Thereafter, when the piezo stack 2 is contracted by electric discharge, the first piston 41 is moved upward by the urging force of the preset spring 3, the pressure of the oil tight chamber 42 is lowered, and the pressing force of the valve body 51 is released. Then, the valve body 51 again moves upward to close the low pressure passage 54, the pressure in the back pressure chamber 46 communicating with the high pressure passage 52 rises again, the nozzle needle 5 is lowered, and the injection is finished.

  In the present embodiment, the piezo drive device 1 includes the preset spring 3 that applies a preload to the piezo stack 2 by the annular spring member 31 whose center of the plate surface is recessed into a substantially V-shape, so that it can be installed in the same space. The spring force is larger than that of a conventional disc spring, and a necessary load can be easily applied to the piezo stack 2. The shape of the spring member 31 is equivalent to a structure in which conventional disc springs are arranged in parallel, and the annular half on the inner peripheral portion 311 side and the annular half on the outer peripheral portion 313 are respectively equivalent to conventional disc springs. Therefore, the load of one spring member is reduced and the structure is strong against drooping.

  Further, the two spring members 31 are combined to form a vertically and horizontally symmetrical structure, and the inner peripheral portions 311 and the outer peripheral portions 312 are in contact with each other, and the intermediate portion 313 is in contact with the first piston 41 and the plate member 16. Therefore, even if the spring member 31 expands and contracts due to the displacement of the first piston 41 which is a movable member, no relative slip occurs at the contact portion. Therefore, the occurrence of wear can be prevented.

  By using such a spring member 31, the piezo drive device 1 capable of transmitting the expansion and contraction of the piezo stack 2 quickly and efficiently is obtained. Further, since the hydraulic transmission device has a compact configuration, a small, high-performance and highly reliable piezo drive device 1 can be realized, and the injection controllability of the piezo injector can be improved.

  In the above embodiment, the application example of the piezo injector to the piezo drive device 1 has been shown. However, the spring member 31 of the present invention is supported by the movable member 71 at one end side and the fixed member 72 at the other end side as shown in FIG. Any load loading mechanism that applies an initial load to a predetermined member (not shown) via the movable member 71 can be used. Even in such a load-loading mechanism, the spring member 31 achieves desired spring characteristics with a small installation space (can be arbitrarily adjusted from a small spring force to a large spring force), and even if the movable member 71 is displaced, the intermediate portion 312 Since the relative sliding does not occur at the contact portion between the movable member 72 and the movable member 72, the same effect that the occurrence of wear can be suppressed can be obtained.

  Further, as shown in FIG. 7, a composite spring in which a plurality of spring members 31 are combined may be disposed between the movable member 71 and the fixed member 72. Also in this case, by disposing the inner peripheral portions 311 and the outer peripheral portions 313 of the plurality of spring members 31 in contact with each other, the displacement is large and the spring force is small to large in a relatively small installation space. It can be a composite spring. Further, since the movable member 71 and the fixed member 72 are brought into contact with the intermediate portion 312, it is possible to prevent the occurrence of wear by eliminating relative slip at the contact portion.

  Further, as shown in FIG. 8, the spring member 31 may be divided into two parts, that is, an inner peripheral side half 31a and an outer peripheral side half 31b. That is, the inner peripheral half 31a and the outer peripheral half 31b are formed of annular leaf springs having different outer diameters, and the plate surfaces are inclined in opposite directions. By dividing the inner half 31a and the outer half 31b in this way, the spring force is slightly smaller than the non-divided shape, but it is more than the shape of the spring member 31 by press molding a single flat plate. Manufacturing becomes easy. Therefore, it is advantageous when it is desired to easily obtain a desired effect, and can be arbitrarily adjusted from a small spring force to a small spring force in a small space, and a composite spring having a large displacement can be obtained.

  As described above, the spring member of the present invention can be suitably used as a spring member for a piezo drive device or other load loading mechanism. In the above embodiment, only the spring member having a substantially V-shaped cross section in the radial direction of the plate surface is shown. However, the present invention is not limited to this, and the inner peripheral portion and the outer peripheral portion are warped in the same direction, and the intermediate portion is stretched in the opposite direction. The same effect can be obtained as long as the shape is obtained.

  The configuration of the piezo drive device and the piezo injector to which the spring member of the present invention is applied is not limited to that shown in the above embodiment. For example, in the above-described embodiment, the displacement transmission device of the piezo drive device is configured such that the second piston is accommodated in the first piston. However, if there is room in the space, the first piston and the second piston are connected. They may be arranged side by side in the axial direction. Moreover, it is good also as a structure which enlarges and transmits the displacement of a 1st piston by making the pressure receiving area of a 1st piston larger than a 2nd piston. Furthermore, although the said embodiment was taken as the example applied to the injector which drives the control valve of a three-way valve structure, a control valve may be made into a two-way valve structure, or the back pressure control mechanism of a nozzle needle may differ.

It is a figure which shows the 1st Embodiment of this invention, (a) is a perspective view which shows the whole structure of a spring member, (b) is a perspective view which shows the radial direction cross section of a spring member. It is radial direction sectional drawing of the spring member of 1st Embodiment. It is sectional drawing which shows the spring member shape in the 2nd Embodiment of this invention. It is sectional drawing which shows the whole structure of the piezo-type injector incorporating the piezo drive device of this invention. FIG. 5A is an enlarged sectional view of FIG. 4A, and FIG. 5B is a radial sectional view of a preset spring using the spring member of the present invention. It is sectional drawing which shows the structural example of the load load mechanism using the spring member of this invention. It is sectional drawing which shows the other structural example of the load load mechanism using the spring member of this invention. It is sectional drawing which shows the further another structural example of the load load mechanism using the spring member of this invention. (A) is the fragmentary sectional view which shows the principal part structure of the conventional piezo drive device, (b) is the B figure expanded sectional view of FIG. It is a partial expanded sectional view which shows the principal part structure of the conventional piezo drive device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric drive device 11 Casing 12 Connector 13 Rod 14 Disc-shaped member 15 Bellows 2 Piezo stack 3 Preset spring 31 Spring member 311 Inner ring part 312 Outer ring part 313 Middle ring part 41 First piston 42 Oiltight chamber 43 Second piston 44 Check valve 45 Nozzle needle 46 Back pressure chamber 47 Injection hole 5 Control valve 51 Valve body 52 High pressure passage 53 Spring 54 Low pressure passage 61 Vertical hole 62 High pressure fuel passage 64 Low pressure fuel passage

Claims (8)

  One end side is supported by a movable member and the other end side is supported by a fixed member. The load member is a spring member for a load mechanism that applies a predetermined load via the movable member, and is composed of an annular leaf spring. The circumferential annular portion and the outer circumferential annular portion are warped in the same direction, and a shape having an intermediate annular portion protruding in a direction opposite to the warping direction is provided between the inner circumferential annular portion and the outer circumferential annular portion. Spring member.   The spring member according to claim 1, wherein the annular leaf spring has a substantially V-shaped cross section in the radial direction of the plate surface.   The spring member according to claim 1 or 2, wherein the annular leaf spring constituting the spring member is formed by press-molding a single annular flat plate.   4. The spring member according to claim 1, wherein in the annular leaf spring, the plate thickness of the intermediate annular portion is larger than the plate thicknesses of the inner circumferential annular portion and the outer circumferential annular portion. When the maximum plate thickness of the annular leaf spring is Tmax, the inner diameter is Din, and the outer diameter is Dout, the following formula (1)
Tmax ≦ (Dout−Din) / 4 (1)
The spring member according to any one of claims 1 to 4, wherein:   The spring member is composed of a composite spring in which a plurality of the annular leaf springs are combined, and at least two of the plurality of annular leaf springs are such that the inner circumferential annular portion and the outer circumferential annular portion abut against each other. The spring member according to claim 1, wherein the spring member is arranged. A piezo drive device using the spring member according to any one of claims 1 to 6,
The annular leaf spring is provided between a movable member and a fixed member that are displaced following the piezo element,
A piezo drive device, wherein a preload is applied to the piezo element by the annular leaf spring. A piezo drive device according to claim 7, a control valve driven by the piezo drive device, and a control chamber for applying a pressure in a valve closing direction to a nozzle needle, wherein the control chamber and the low-pressure passage are controlled by the control chamber. A piezo-type injector characterized in that fuel injection is controlled by increasing or decreasing the pressure in the control chamber by opening and closing with a valve.

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