JP2007270872A - Accumulator and diaphragm for accumulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an accumulator with nobel structure, stably deforming a diaphragm on its center axis in fluctuation in working pressure, and to provide a diaphragm for an accumulator. <P>SOLUTION: A plurality of rib groups 56 are disposed on an inner peripheral face of an inner annular elastic member layer 36 of the diaphragm 12 so that the groups are spaced from each other at predetermined intervals in the meridian direction. Each rib group 56 is constituted of a plurality of streaks of annular ribs 54 which are concentrically extended around an apex as their center. Rigidity of the annular ribs 54 of the rib group 56 gets larger, according to the position of the rib group 56 from the apex toward outer peripheral side in the meridian direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an accumulator which is employed in, for example, a hydraulic circuit in an automobile or an industrial machine and used as a pressure accumulating unit for a medium such as hydraulic oil and a diaphragm constituting the accumulator.

  Conventionally, in hydraulic circuits in automobiles and industrial machines, accumulators have been used for the purpose of accumulating hydraulic fluid or absorbing pulsation. Such an accumulator, for example, as described in Patent Document 1 (Japanese Patent Laid-Open No. 08-014202), accommodates and arranges a diaphragm inside a hollow housing, and divides the inner space of the hollow housing into a fluid-tight manner by the diaphragm. The structure is In addition, one fluid tight region in the housing is a sealed gas chamber, while the other fluid tight region is a liquid chamber connected to a hydraulic line or the like. Then, by backing up the pressure of the liquid chamber connected to the hydraulic pipeline with the gas pressure of the gas chamber via the diaphragm, the hydraulic pressure in the hydraulic pipeline is accumulated or the pulsation is absorbed. It has become.

  By the way, the diaphragm in such an accumulator is required to have a high degree of impermeability to the gas sealed in the gas chamber and the medium (liquid such as hydraulic fluid) guided to the liquid chamber, and the diaphragm does not reach the liquid chamber. Sufficient deformation performance and durability are required for repeated deformation according to the pressure fluctuation.

  Therefore, as such a diaphragm, in order to realize impermeability to gas and medium and good deformability, as shown in the above-mentioned Patent Document 1, an inner rubber layer and an outer rubber layer are sandwiched between resin layers. Has a hemispherical shell shape under the condition that no external force is applied. Such a diaphragm is accommodated inside the hollow housing, and by holding the peripheral edge of the opening firmly to the inner peripheral surface of the hollow housing, the inner space of the hollow housing is made convex in the liquid chamber side. The structure is divided into two fluids.

  However, since such a diaphragm has a hemispherical shell shape having a resin layer, due to the rigidity of the resin layer, valley-like bending extending in the meridian direction occurs at a plurality of locations on the circumference during elastic deformation. There is a problem that durability is easily lowered due to such bending. Therefore, as described in Patent Document 1, by integrally forming a plurality of annular ribs extending concentrically around the apex on the inner surface of the diaphragm, the rigidity in the circumferential direction is improved and the meridian direction is increased. It is designed to avoid the trough-like bending that extends.

  However, even if valley-like bending extending in the meridian direction can be avoided, it is inevitable that the diaphragm is elastically deformed in a direction inclined with respect to the central axis. That is, it is desirable that the hemispherical diaphragm is elastically deformed while maintaining rotational symmetry with respect to the central axis, thereby exhibiting stable elastic deformation characteristics and good durability. In reality, however, the deformation center axis of the diaphragm is inclined from the geometric center axis due to variations in the wall thickness of the resin layer and the inner and outer rubber layers, etc., resulting in distorted deformation that does not dent in an oblique direction. There is a case.

  When such a distorted deformation occurs, the deformed part at one place on the circumference easily reaches the peripheral edge of the opening of the diaphragm fixed to the housing, and large bending and stress concentration occur there. Durability may be reduced. Moreover, if the deformation mode of the diaphragm is different between individual products, there is a problem that it becomes difficult to ensure the reliability of the product and the stability of the performance.

  In order to cope with such a problem, the present applicant previously described in Patent Document 2 (Japanese Patent Laid-Open No. 2005-315297) a plurality of annular ribs extending in the circumferential direction formed on the inner peripheral surface of the diaphragm. A structure has been proposed in which the rigidity is gradually (stepwise or gradually) increased from the portion toward the outer peripheral side in the meridian direction.

  In the diaphragm having such a structure, the ease of elastic deformation is changed in the meridian direction due to the difference in rigidity of the plurality of annular ribs, and as a result of the deformation progressing gradually toward the outer peripheral side from the easily deformable central portion, The elastic deformation on the central axis of the diaphragm is promoted, and the dent in the direction inclined with respect to the central axis of the diaphragm is suppressed.

  However, as a result of further studies by the inventor, for example, depending on the size of the diaphragm, required characteristics, etc., a sufficient rigidity difference in the meridian direction with respect to the annular rib formed on the inner peripheral surface of the diaphragm is set. It turns out that there are cases where it is difficult. Especially in the case of small diaphragms, thin diaphragms, etc., if the annular rib is enlarged to increase the rigidity of the annular rib, smooth deformation is inhibited, and on the contrary, a bending line extending in the circumferential direction is generated, resulting in stress. Concentration can be a problem. Therefore, even in the invention described in the prior application (Patent Document 2), there is still room for improvement regarding the realization of the stability of the deformation mode of the diaphragm.

Japanese Patent Laid-Open No. 08-014202 JP 2005-315297 A

  Here, the present invention has been made in the background as described above, and the problem to be solved is that the deformation of the diaphragm when the working pressure fluctuates is stably expressed on the central axis. It is to provide an accumulator having a novel structure, and to provide a diaphragm for an accumulator.

  Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible. Further, aspects or technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or an invention that can be understood by those skilled in the art from those descriptions. It should be understood that it is recognized based on thought.

  A feature of the present invention is that a diaphragm having a hemispherical shell shape is formed in a state where an inner elastic material layer and an outer elastic material layer are integrally formed with a resin layer interposed therebetween and no external force is applied. In the accumulator in which the opening peripheral edge of the diaphragm is fixedly held on the inner peripheral surface of the hollow housing and the inner space of the hollow housing is divided into two fluid-tightly, the inner peripheral surface of the inner elastic material layer in the diaphragm In addition, a plurality of rib groups composed of a plurality of annular ribs extending concentrically around the apex are provided at a predetermined distance from each other in the meridian direction. The reason is that the rib is formed with great rigidity.

  In such an accumulator having a structure according to the present invention, when a pressure such as hydraulic fluid is applied from the outside to the accumulator, the pressure is applied to the outer peripheral surface (convex surface) of the hemispherical diaphragm. The diaphragm is elastically deformed by being pushed from the outer peripheral surface until it reaches an equilibrium state with the gas pressure sealed on the inner peripheral surface (concave surface) side.

  At that time, in such a diaphragm, since the outer peripheral edge portion is fixedly held, the deformation starts to be recessed from the center where the deformation rigidity is small, but the central axis of the recess in the deformation form is the center of the diaphragm. When tilted obliquely from the axis (that is, when the center point of the dent deviates from the apex of the diaphragm), the outer peripheral edge of the dent is located on the rib group, and the outer periphery beyond the rib group. It straddles the part located in the non-formed part on the side. When the dent further advances, the portion located in the non-formed portion of the rib group in the outer peripheral edge of the dent reaches the formed portion of the rib group composed of the annular rib having higher rigidity located further on the outer peripheral side thereof. . As a result, at the position where the formation portion of the rib group composed of the annular rib having the higher rigidity is reached, the deformation rigidity is greatly changed, so that the progress of the outer peripheral edge of the dent to the outer peripheral side is suppressed. Thus, the advancement of the outer peripheral edge of the dent is preferentially advanced at other positions that are more easily deformed.

  As a result, the recess is aligned at the position where the entire circumference of the outer peripheral edge reaches the formation portion of the rib group composed of the annular rib having higher rigidity, so that the center axis of the recess becomes the center axis of the diaphragm. It will be matched.

  Therefore, in the accumulator having the structure according to the present invention, by providing a plurality of rib groups at a predetermined distance in the meridian direction in the diaphragm, a large difference is provided in the rigidity difference between the respective annular ribs constituting each rib group. Even if it is not, the deformation rigidity at the time of the progress of the recess toward the outer peripheral side can be greatly changed at the position where the outer peripheral edge of the recess starts to be applied to each rib group. Therefore, when the deformation of the diaphragm proceeds, at least in the stage where the outer peripheral edge of the recess starts to be applied to each rib group, the inner peripheral edge of the recess is once aligned with the circumferential line on the central axis of the diaphragm. This can effectively prevent a large deviation of the recess relative to the central axis of the diaphragm.

  In the present invention, the specific shape and size of the annular ribs constituting each rib group are not particularly limited. For example, as a method for varying the rigidity of the annular rib, for example, changing the cross-sectional area by varying the height or width of the annular rib is preferably employed. Further, as the annular rib, any of a trapezoidal shape, a triangular shape, a mountain shape, or the like can be adopted as the cross-sectional shape, and a V-shape or a U-shape can be adopted as the shape between the annular ribs.

  Then, when showing a preferable example of the present invention, the protruding height of the annular rib of the rib group positioned on the outer peripheral side in the meridian direction is higher than the annular rib of the rib group positioned on the inner peripheral side in the meridian direction. A configuration in which the rigidity is increased by increasing the width can be adopted.

  Moreover, as a preferable aspect of the present invention, a configuration in which each of the plurality of annular ribs constituting the same rib group has the same cross-sectional shape may be employed.

  In the present invention, it is not essential that a plurality of annular ribs constituting the same rib group have the same cross-sectional shape and size in one rib group. In one rib group, an annular rib having a gradually increasing cross-sectional area may be formed step by step toward the outer peripheral side in the meridian direction.

  In the accumulator having the structure according to the present invention, the distance between the plurality of rib groups adjacent to each other in the meridian direction is larger than the width dimension of one annular rib and smaller than the width dimension of the rib group. The configuration is preferably adopted.

  If the distance between the rib groups is too small, the outer peripheral edge of the recess in the diaphragm does not sufficiently exhibit the change in rigidity when reaching the rib group as described above, and the outer peripheral edge of the recess is aligned there. This is because the effect is hardly exhibited effectively. On the other hand, if the distance between the rib groups is too large, the number of the annular ribs becomes too small, and the effect of the annular ribs, that is, the effect of preventing the valley-like bending deformation extending in the meridian direction as described above is sufficiently exhibited. This is because it may be difficult.

  Further, in the accumulator having the structure according to the present invention, a configuration in which the thickness of the diaphragm is constant as a whole in a portion where the rib group is not formed is preferably employed.

  This makes it possible to more advantageously set the deformation rigidity difference between the portion where the rib group is formed and the portion where the rib group is not formed. However, in the present invention, for example, the thickness dimension of the portion where the rib group is not formed is gradually increased from the apex of the diaphragm toward the outer peripheral side in the meridian direction, and the deformation rigidity in the base portion is also increased toward the outer peripheral side. It is also possible to set a large value.

  The thickness of the diaphragm is appropriately set according to the size and shape of the diaphragm, required characteristics, and the like. Therefore, the protrusion height dimension of the annular rib relative to the wall thickness dimension of the base part of the diaphragm (the part where the rib group is not formed) depends on the viewpoint of preventing buckling of the resin layer and the distortion generated in the inner and outer elastic material layers. From the viewpoint of suppressing the size, the protrusion height of the annular rib is set in the range of 0.2 t to 0.7 t with respect to the thickness dimension: t of the base portion including the resin layer and the inner and outer elastic material layers. It is desirable.

  Furthermore, the present invention provides an inner elastic material in an accumulator diaphragm in which an inner elastic material layer and an outer elastic material layer are integrally formed with a resin layer interposed therebetween and has a hemispherical shell shape in a state where no external force is exerted. A plurality of rib groups each including a plurality of annular ribs extending concentrically around the apex are provided on the inner peripheral surface of the layer at a predetermined distance in the meridian direction, and the ribs are positioned on the outer peripheral side in the meridian direction from the apex. The group also features an accumulator diaphragm in which the annular ribs are formed with greater rigidity.

  Moreover, in this diaphragm for accumulators, all the various arbitrary additional structures suitably employ | adopted in the diaphragm which concerns on the above-mentioned this invention can be applied as needed.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described. First, FIG. 1 shows a pressure accumulator 10 as an embodiment according to the accumulator of the present invention. The pressure accumulator 10 houses a pressure accumulator diaphragm 12 as an embodiment of the accumulator diaphragm of the present invention inside a shell 14 as a hollow housing, and an opening peripheral edge of the diaphragm 12 is an inner peripheral surface of the shell 14. The housing space 16 as the internal space of the shell 14 is fluid-divided into two parts by adhering to and holding. In the following description, the vertical direction refers to the vertical direction in FIG. 1 unless otherwise specified.

  More specifically, the shell 14 includes a first instrument member 18 and a second instrument member 20. Each of the first and second vessel members 18 and 20 has a rotationally symmetric shape centered on the apex of a substantially semicircular cross section, has a so-called hemispherical shell shape, and is made of a metal material, a resin material, or the like. It is formed using a hard material.

  A supply hole 22 is provided at the apex portion of the first vessel member 18, and a sealing member 24 described later is fitted into the supply hole 22.

  A through hole 26 is formed through the apex portion of the second instrument member 20 having a larger volume than the first instrument member 18. The inner peripheral surface and the outer peripheral surface of the second vessel member 20 around the through hole 26 and extending over a region having a predetermined size having an annular shape are substantially flat. The end surface of the cylindrical connection fitting 28 is superimposed on the outer peripheral surface around the through hole 26 and fixed by welding or the like. A screw portion 30 is provided on the outer peripheral surface of the connection fitting 28. The through hole 26 and the inner hole of the connection fitting 28 cooperate to constitute a port for connecting the inside of the second instrument member 20 to a hydraulic pipe line (not shown).

  Furthermore, the inner peripheral surface in the vicinity of the opening of the second container member 20 is provided with a fitting groove 32 extending in the circumferential direction with a predetermined length (in this embodiment, the entire circumference).

  The opening end portions of the first instrument member 18 and the second instrument member 20 are overlapped with each other, and are fixed in close contact by welding, adhesion, or the like, so that an outer spherical shell 14 is formed, A substantially spherical accommodation space 16 is provided therein. The accumulator diaphragm 12 accommodates the pressure accumulator diaphragm 12.

  As shown in FIG. 2, the pressure accumulator diaphragm 12 has a hemispherical shell shape as a whole in a state where no external force is exerted. The pressure accumulator diaphragm 12 has a three-layer structure in which an inner elastic material layer 36 and an outer elastic material layer 38 are integrally provided with a resin layer 34 interposed therebetween.

  The resin layer 34 has a substantially hemispherical shell shape, and is formed using a resin material having characteristics such as flexibility and prevention or suppression of gas permeation. Specifically, for example, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyvinylidene fluoride, polyvinylidene chloride, or a composite material thereof is employed. The resin layer 34 may be overlaid with a reinforcing material made of woven fabric or nonwoven fabric, if necessary. The resin layer 34 is indicated by a solid line in the drawing because the thickness dimension thereof is extremely smaller than the thickness dimension of the inner elastic material layer 36 and the outer elastic material layer 38.

  Each of the inner elastic material layer 36 and the outer elastic material layer 38 has a substantially hemispherical shell shape and is made of a rubber elastic film that can be elastically deformed. For such a rubber elastic film, for example, butyl rubber, nitrile rubber, hydrin rubber, or a composite material thereof is employed. The outer peripheral surface of the inner elastic material layer 36 is vulcanized and bonded to the inner peripheral surface of the resin layer 34, and the inner peripheral surface of the outer elastic material layer 38 is vulcanized and bonded to the outer peripheral surface of the resin layer 34. The pressure accumulator diaphragm 12 is configured by sandwiching the resin layer 34 between the inner elastic material layer 36 and the outer elastic material layer 38. That is, the pressure accumulator diaphragm 12 is formed as an integrally vulcanized molded product of the inner and outer elastic material layers 36 and 38 including the resin layer 34.

  Further, a fitting protrusion 40 is integrally formed on the inner peripheral surface near the opening of the inner elastic material layer 36 and protrudes radially inward. The fitting protrusion 40 has a constant semi-circular cross section and extends in the circumferential direction with a predetermined length (in this embodiment, the entire circumference).

  Further, at the apex portion of the pressure accumulator diaphragm 12, a substantially truncated frusto-conical central protrusion 42 formed integrally with the inner and outer elastic material layers 36 and 38 is projected inward in the radial direction. In addition, a fitting recess 44 that opens to the outer peripheral surface of the outer elastic material layer 38 is formed in the central portion of the central protrusion 42. The bottom of the fitting recess 44 is positioned in the outer elastic material layer 38 radially outward from the resin layer 34 sandwiched between the inner and outer elastic material layers 36 and 38. The peripheral wall portion of the fitting recess 44 is provided with one or more ridges or ridges extending in the circumferential direction. A poppet 46 is disposed in the fitting recess 44.

  The poppet 46 has a substantially truncated truncated cone shape and is formed using a hard material such as a resin material or a metal material. In the present embodiment, the outer peripheral surface of the poppet 46 has a shape corresponding to the peripheral wall portion of the fitting recess 44, and the inner elastic material layer 36 and the outer elastic material layer 38 provided with the resin layer 34 are integrally vulcanized. In this case, after the fitting recess 44 is formed, the poppet 46 is fitted into the fitting recess 44, and the outer peripheral surface of the poppet 46 and the peripheral wall portion (surface) of the fitting recess 44 are engaged with each other by the concave and convex portions. As a result, the poppet 46 is fixedly supported by the apex portion of the pressure accumulator diaphragm 12. In short, the rigidity of the apex portion is increased by disposing the poppet 46 made of a hard material at the apex portion of the pressure accumulator diaphragm 12. Further, the end surface on the large diameter side of the poppet 46 is flat and is flush with the outer peripheral surface of the peripheral edge portion of the fitting recess 44 of the outer elastic material layer 38. The poppet 46 can be fixed by vulcanizing and bonding to the fitting recess 44 when the inner and outer elastic material layers 36 and 38 and the resin layer 34 are integrally vulcanized.

  The pressure accumulator diaphragm 12 is fitted from the opening of the second instrument member 20, and the central axis passing through the apex of the accumulator diaphragm 12 is positioned substantially on the same line as the central axis passing through the apex of the second instrument member 20. I'm hurt.

  Further, in the meridian direction from the apex of the pressure accumulator diaphragm 12 or the second instrument member 20 toward the outer peripheral side, the fitting groove 32 of the second instrument member 20 is more than the fitting protrusion 40 of the inner elastic material layer 36. It is located outside. An engagement ring 48 as a fixing means is attached to the fitting groove 32 and the fitting projection 40.

  The engagement ring 48 has a large-diameter ring shape, is formed using a thin metal material, and has elasticity. Further, the engaging ring 48 has an axially upper portion positioned radially outwardly with a stepped portion extending radially in the axially intermediate portion, and an axially lower portion positioned radially inward. As a whole, it extends continuously in the circumferential direction with a curved or bent cross section. In the state where no external force is applied to the engagement ring 48, the outer diameter of the upper part in the axial direction is made larger than the diameter of the fitting groove 32 of the second instrument member 20, and the outer diameter of the lower part in the axial direction is The diameter dimension is made larger than the inner diameter dimension of the fitting protrusion 40 of the inner elastic material layer 36.

  The fitting protrusion 40 of the inner elastic material layer 36 is elastically deformed and fitted into a groove-like portion formed by cooperation of the step portion of the engagement ring 48 and the lower portion in the axial direction. The upper part of the ring 48 in the axial direction is elastically deformed and fitted into the fitting groove 32 of the second instrument member 20, and the fitting projection 40 is based on the elasticity of the engagement ring 48 and the fitting projection 40. The outer peripheral surface of the outer elastic material layer 38 on the outer peripheral side is superimposed and fixed in close contact with the inner peripheral surface of the second container member 20. Thereby, the opening peripheral part of the diaphragm 12 for pressure accumulators is adheringly hold | maintained at the internal peripheral surface of the 2nd container member 20. FIG.

  Furthermore, as described above, the opening end of the first instrument member 18 and the opening end of the second instrument member 20 are overlapped in the axial direction (up and down in FIG. 1) and fixed by welding or the like. As a result, the accommodation space 16 is provided inside the shell 14 including the first and second container members 18 and 20, and the opening peripheral edge of the pressure accumulator diaphragm 12 is formed on the inner peripheral surface of the accommodation space 16. The holding space 16 is bisected in a fluid-tight manner by being firmly held.

  A part of the wall portion is formed by the inner elastic material layer 36 of the pressure accumulator diaphragm 12 on one side (the upper side in FIG. 1) of the pressure accumulator diaphragm 12 in the accommodation space 16. A gas chamber 50 is formed. The gas chamber 50 is filled with a gas such as nitrogen gas from the supply hole 22 of the first vessel member 18, and a sealing member 24 such as a rivet is supplied through a seal member such as a weld or an O-ring. Since the gas chamber 50 is filled with a gas having a predetermined pressure, the gas chamber 50 is fluid-tightly sealed. Based on the pressure in the gas chamber 50, the outer peripheral surface of the outer elastic material layer 38 of the pressure accumulator diaphragm 12 is superimposed on the inner peripheral surface of the second container member 20 and passes through the apex of the pressure accumulator diaphragm 12. The central axis is positioned collinearly with the central axis passing through the apex of the second instrument member 20, and the large-diameter side end surface of the poppet 46 of the pressure accumulator diaphragm 12 and the through hole 26 of the second instrument member 20 The inner peripheral surfaces are overlapped with each other.

  Further, on the other side of the second container member 20 (lower side in FIG. 1) sandwiching the pressure accumulator diaphragm 12 in the accommodation space 16, a part of the wall portion is an outer elastic material layer 38 of the pressure accumulator diaphragm 12. Is formed (see FIGS. 4 and 5). No hydraulic oil or the like, which will be described later, is placed in the liquid chamber 52, and the outer elastic material layer 38 of the accumulator diaphragm 12 is substantially spaced from the inner peripheral surface of the second device member 20 based on the pressure in the gas chamber 50. In a state where the liquid chambers 52 are superposed without being overlaid (the state shown in FIG. 1), the liquid chamber 52 has almost no volume. The gas chamber 50 and the liquid chamber 52 are fluid-tightly blocked by the resin layer 34 of the pressure accumulator diaphragm 12.

  In this case, the inner peripheral surface of the inner elastic material layer 36 of the pressure accumulator diaphragm 12 between the central protrusion 42 and the fitting protrusion 40 is a rib composed of a plurality of annular ribs 54 extending concentrically around the apex. A plurality of groups 56 are provided at a predetermined distance from each other in the meridian direction. In the present embodiment, three rib groups 56 are provided, and the apex of the pressure accumulator diaphragm 12, that is, from the inner peripheral side to the outer peripheral side in the meridian direction around the central axis of the poppet 46 arranged at the apex. A first rib group 56a, a second rib group 56b, and a third rib group 56c are formed toward the peripheral edge of the opening.

  Each rib group 56 includes three annular ribs 54, 54, 54. The annular rib 54 is integrally formed with the inner elastic material layer 36 of the pressure accumulator diaphragm 12, and is continuously provided in the meridian direction in each rib group 56. Further, the three annular ribs 54, 54, 54 in each rib group 56 have the same cross-sectional shape and size. Further, each of the annular ribs 54a of the first rib group 56a, each of the annular ribs 54b of the second rib group 56b, and each of the annular ribs 54c of the third rib group 56c are all the inner circumference of the inner elastic material layer 36. The trapezoidal cross section has a width dimension that decreases toward the inside of the pressure accumulator diaphragm 12 protruding from the base end portion in contact with the surface, and extends continuously in the circumferential direction of the pressure accumulator diaphragm 12. In short, the three annular ribs 54 constituting each rib group 56, that is, a total of nine annular ribs 54, have the same cross-sectional shape not only in each rib group 56 but also in different rib groups 56a, 56b, and 56c. Yes.

  In particular, in the meridian direction from the apex of the pressure accumulator diaphragm 12, the protruding height h1 of the annular rib 54a of the first rib group 56a positioned on the inner peripheral side is positioned on the outer peripheral side of the first rib group 56a. The projection height of the annular rib 54b of the second rib group 56b is smaller than the projection height h2 and the projection height h2 of the annular rib 54b of the second rib group 56b is the second rib group. The protrusion height of the annular rib 54c of the third rib group 56c located on the outer peripheral side of 56b is made smaller than h3. Specifically, for example, the protrusion height: h1 of the annular rib 54a of the first rib group 56a is set to h1 = 0.3t with respect to the wall thickness dimension: t of the pressure accumulator diaphragm 12. Projection height h2 of the annular rib 54b of the second rib group 56b is set to h2 = 0.5t, and projection height h3 of the annular rib 54c of the third rib group 56c is h3 = 0.7t. It is said that.

  As is clear from this, in the present embodiment, the protruding height of each annular rib 54 is made smaller than the thickness dimension t of the pressure accumulator diaphragm 12. The thickness t of the pressure accumulator diaphragm 12 is the thickness of the diaphragm 12 where the fitting protrusion 40, the central protrusion 42, and the first to third rib groups 56a, 56b, and 56c are not provided. The dimension refers to a dimension, and in the present embodiment, it is generally constant as a whole.

  The width dimension w1 of the annular rib 54a of the first rib group 56a is smaller than the width dimension w2 of the annular rib 54b of the second rib group 56b, and the second rib group 56b. The width dimension w2 of the annular rib 54b is smaller than the width dimension w3 of the annular rib 54c of the third rib group 56c.

  That is, as compared with the annular rib 54 of the rib group 56 located on the inner circumferential side in the meridian direction, the annular rib 54 of the rib group 56 located on the outer circumferential side in the meridian direction has a protruding height and a width dimension. It has been enlarged. As a result, as the rib group 56 located on the outer peripheral side in the meridian direction from the apex of the pressure accumulator diaphragm 12, the annular rib 54 is formed with greater rigidity.

  Further, the central protrusion 42, the first rib group 56a, the first rib group 56a, the second rib group 56b, the second rib group 56b, the third rib group 56c, the third rib group 56c, and the fitting. The landing protrusions 40 are positioned at a predetermined distance in the meridian direction. In particular, the distance between the first rib group 56a and the second rib group 56b adjacent to each other in the meridian direction and the distance between the second rib group 56b and the third rib group 56c are the same. In addition to the above, the distance l is larger than the width dimension w3 of one of the largest annular ribs 54c in the plurality of annular ribs 54, and the smallest first in the plurality of rib groups It is made smaller than the width dimension of the rib group 56a. Further, the distance between the rib groups 56 adjacent to each other in the meridian direction is a separation distance between the first rib group 56a and the central protrusion 42 or a separation distance between the third rib group 56c and the fitting protrusion 40. It is smaller than

  In the pressure accumulator 10 including the pressure accumulator diaphragm 12 having the above-described structure, the screw portion 30 of the connection fitting 28 fixed to the second device member 20 is not shown in a hydraulic pipe such as an automobile or industrial machine. The fluid chamber 52 is connected to the hydraulic pipe line via the connection fitting 28 by being screwed and fixed to the road. For example, lubricating oil such as mission oil or brake oil or hydraulic equipment is operated to transmit power. A medium such as hydraulic oil for performing the above is introduced into the liquid chamber 52 through the inner hole of the connection fitting 28 and the through hole 26 of the second container member 20. When the pressure of the liquid chamber 52 becomes larger than the pressure of the gas chamber 50 due to the medium introduced into the liquid chamber 52 from the through hole 26, the accumulator diaphragm 12 is changed based on the pressure difference between the gas chamber 50 and the liquid chamber 52. The medium is stored in a pressurized state in the liquid chamber 52 based on the elastic deformation so as to swell toward the gas chamber 50 and the compression of the gas chamber 50. Further, the pulsation of the medium can be absorbed by utilizing the elastic deformation action of the pressure accumulator diaphragm 12 based on the pressure difference between the gas chamber 50 and the liquid chamber 52.

  Here, the pressure accumulator diaphragm 12 has a structure in which the resin layer 34 is sandwiched between the inner elastic material layer 36 and the outer elastic material layer 38, so that the gas enclosed in the gas chamber 50 and the liquid chamber 52 are contained. A high degree of impermeability can be achieved for the guided medium and sufficient deformation performance is obtained for repeated deformations in response to pressure fluctuations exerted on the liquid chamber 52.

  Meanwhile, as shown in FIG. 6, in the pressure accumulator 60 including the pressure accumulator diaphragm 62 having a conventional structure in which the inner elastic material layer 36 and the outer elastic material layer 38 are integrally formed with the resin layer 34 interposed therebetween. The problem that distortion occurs in the elastic deformation of the pressure accumulator diaphragm 62 is inherent. In order to clarify the location of this problem, a pressure accumulator 60 having a pressure accumulator diaphragm 62 having a conventional structure will be described below, but a member having substantially the same structure as the pressure accumulator 10 according to the present embodiment. And about a site | part, the same code | symbol as this embodiment is attached | subjected in a figure, and those detailed description is abbreviate | omitted.

  That is, on the inner peripheral surface between the central protrusion 42 and the fitting protrusion 40 of the inner elastic material layer 36 in the conventional pressure accumulator diaphragm 62, a plurality of annular rings extending concentrically around the apex of the diaphragm 62. Ribs 64 are integrally formed. The annular rib 64 has a trapezoidal cross section in which the width dimension decreases toward the inside of the pressure accumulator diaphragm 12 protruding from the base end portion in contact with the inner peripheral surface of the inner elastic material layer 36, and is continuous in the circumferential direction of the pressure accumulator diaphragm 12. It extends. The plurality of annular ribs 64 have substantially the same shape and size, and the plurality of annular ribs 64 are continuously provided without separating the annular ribs 64 adjacent to each other in the meridian direction.

  In the pressure accumulator diaphragm 62 having such a conventional structure, the circumferential rib 64 is increased in rigidity in the circumferential direction, and due to the rigidity of the resin layer 34 having a hemispherical shell shape, the meridian is formed at a plurality of locations on the circumference at the time of elastic deformation. The valley-like bending extending in the direction is suppressed.

  However, as shown in FIGS. 7 to 9, as the inflow amount of the liquid chamber 52 into the medium is increased, a dent is generated at one part on the circumference of the diaphragm 62, and the dent part is formed in the diaphragm 62. In some cases, the elastic deformation is greatly caused in the direction inclined with respect to the central axis. When such a distorted deformation occurs, there is a problem that a large bending and stress concentration occur in the deformed portion, resulting in a decrease in durability. One of the causes of such a problem is that the shape and size of each annular rib 64 are substantially the same, and the rigidity of the portion of the diaphragm 62 provided with the annular rib 64 is substantially constant in the meridian direction. Therefore, once the recessed portion is elastically deformed in a direction inclined with respect to the central axis of the diaphragm 62, it becomes difficult to deform so that the central axis of the recessed portion coincides with the central axis of the diaphragm 62. It is assumed that

  Therefore, in the pressure accumulator 10 according to the present embodiment, a plurality of rib groups 56 each including a plurality of annular ribs 54 extending concentrically around the apex of the diaphragm 12 are provided at a predetermined distance from each other in the meridian direction. At the same time, the annular rib 54 is formed with greater rigidity in the rib group 56 located on the outer peripheral side in the meridian direction from the apex.

  That is, when the pressure of the medium is exerted on the liquid chamber 52 of the accumulator 10 from the outside and the pressure is applied to the outer peripheral surface of the outer elastic material layer 38 of the diaphragm 12, the diaphragm 12 is moved to the inner elastic material. It is elastically deformed by being pushed in from the outer peripheral surface until it reaches an equilibrium state with the pressure of the gas chamber 50 sealed on the inner peripheral surface side of the layer 36.

  At that time, in the diaphragm 12, since the outer peripheral edge portion is fixedly held, the deformation starts so as to be recessed from the center having a small deformation rigidity. As shown in FIG. 4, when the central axis of the diaphragm 12 is inclined obliquely (that is, when the central point of the dent deviates from the apex of the diaphragm 12), the outer peripheral edge of the dent becomes the first rib. A portion located on the group 56a and a non-formed portion on the outer peripheral side beyond the first rib group 56a, that is, a portion located in a portion between the first rib group 56a and the second rib group 56b. Try to straddle. When the dent further advances, a portion of the outer peripheral edge of the dent located at the non-formed portion of the first rib group 56a is further formed of the annular rib 54b having a higher rigidity located on the outer peripheral side thereof. The formation portion of the rib group 56b is reached. As a result, at the position where the second rib group 56b formed of the annular rib 54b having a higher rigidity is reached, the deformation rigidity is greatly changed, so that the outer peripheral edge of the recess is further to the outer peripheral side. The progression of the outer peripheral edge of the recess is preferentially advanced at other positions where the progression of the depression is suppressed and the deformation is easier than that.

  As a result, the dent is aligned at a position where the entire circumference of the outer peripheral edge reaches the formation portion of the second rib group 56b composed of the annular rib 54b having higher rigidity, and as shown in FIG. As shown, the center axis of the recess is made to coincide with the center axis of the diaphragm 12.

  In addition, when a larger medium pressure is applied to the liquid chamber 52 from the outside, the central axis of the recess becomes the diaphragm when the diaphragm 12 is elastically deformed so as to be pushed further toward the gas chamber 50 from the outer peripheral surface. The third rib group 56c having a larger rigidity than the second rib group 56b is provided at a predetermined distance on the outer peripheral side of the second rib group 56b. Thus, the central axis of the dent is made to coincide with the central axis of the diaphragm 12 in the same manner as in the deformation mode due to the difference in rigidity between the first rib group 56a and the second rib group 56b.

  Therefore, in the pressure accumulator 10 having the structure according to the present invention, the plurality of rib groups 56 are provided in the diaphragm 12 at a predetermined distance in the meridian direction, so that the rigidity of the respective annular ribs 54 constituting each rib group 56 itself is increased. Even if a large difference is not provided, the deformation rigidity when the recess advances toward the outer peripheral side can be greatly changed at the position where the outer peripheral edge of the recess starts to be applied to each rib group 56. Therefore, as the deformation of the diaphragm 12 proceeds, at least in the stage where the outer peripheral edge of the recess starts to be applied to each rib group 56, the inner peripheral edge of the recess is once aligned with the circumferential line on the central axis of the diaphragm 12. Thus, a large deviation with respect to the central axis of the concave diaphragm 12 can be effectively prevented. As a result, excessive bending and stress concentration in the deformed portion of the diaphragm 12 can be suppressed, and the durability performance can be advantageously improved.

  The embodiment of the present invention has been described in detail above, but this is merely an example, and the present invention is not limited to a specific description in the embodiment, and is based on the knowledge of those skilled in the art. The present invention can be implemented with various changes, modifications, improvements, and the like. Further, it goes without saying that such embodiments are all included in the scope of the present invention without departing from the gist of the present invention.

  For example, the shape, size, structure, number, arrangement, and the like of the annular rib 54 and the rib group 56 according to the embodiment are not limited to those illustrated. Specifically, depending on the standard of the pressure accumulator 10, the required deformation characteristics of the diaphragm 12, the manufacturability, etc., the shape and size of the annular ribs in each rib group are different, or the number of annular ribs is set. It is also possible to increase or decrease, increase or decrease the number of rib groups, or change the distance between rib groups adjacent to each other in the meridian direction.

The longitudinal cross-sectional view of the pressure accumulator as one Embodiment of this invention. The longitudinal cross-sectional view which expands and shows the diaphragm for pressure accumulators used for the same accumulator. The longitudinal cross-sectional view which expands and shows the principal part of the diaphragm for same pressure accumulators. The longitudinal cross-sectional view which shows one action | operation form of the same accumulator. The longitudinal cross-sectional view which shows one action | operation form different from the form of FIG. 4 of the same accumulator. The longitudinal cross-sectional view of the accumulator of conventional structure. The longitudinal cross-sectional view which shows one action | operation form of the pressure accumulator of the conventional structure. The longitudinal cross-sectional view which shows one action | operation form different from the form of FIG. 7 of the pressure accumulator of the conventional structure. The longitudinal cross-sectional view which shows one operation form different from the form of FIG. 7, 8 of the pressure accumulator of the conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Accumulator, 12 ... Diaphragm for accumulator, 14 ... Shell, 34 ... Resin layer, 36 ... Inner elastic material layer, 38 ... Outer elastic material layer, 54a ... Annular rib, 54b ... Annular rib, 54c ... Annular rib, 56a ... 1st rib group, 56b ... 2nd rib group, 56c ... 3rd rib group

Claims (6)

An inner elastic material layer and an outer elastic material layer are integrally formed with a resin layer interposed therebetween, and a diaphragm having a hemispherical shell shape in a state where no external force is exerted is accommodated in a hollow housing, and the diaphragm An accumulator in which the peripheral edge of the opening is fixedly held on the inner peripheral surface of the hollow housing and the internal space of the hollow housing is divided into two fluid-tightly.
On the inner peripheral surface of the inner elastic material layer in the diaphragm, a plurality of rib groups composed of a plurality of annular ribs extending concentrically around the apex are provided at a predetermined distance in the meridian direction, and the meridian direction from the apex The accumulator is characterized in that the annular rib is formed with greater rigidity in the rib group located on the outer peripheral side.   Compared with the annular rib of the rib group located on the inner circumferential side in the meridian direction, the annular rib of the rib group located on the outer circumferential side in the meridian direction has a higher rigidity by increasing the protruding height. The accumulator according to claim 1, which is enlarged.   The accumulator according to claim 1 or 2, wherein in each of the one rib group, the plurality of annular ribs constituting the same group have the same cross-sectional shape.   The distance between the plurality of rib groups adjacent to each other in the meridian direction is larger than the width dimension of one of the annular ribs and smaller than the width dimension of the rib group. The accumulator according to one item.   The accumulator according to any one of claims 1 to 4, wherein a thickness of the diaphragm is constant as a whole in a portion where the rib group is not formed. In the diaphragm for an accumulator having an inner elastic material layer and an outer elastic material layer formed integrally with a resin layer interposed therebetween and having a hemispherical shell shape under the condition that no external force is exerted,
Provided on the inner peripheral surface of the inner elastic material layer are a plurality of rib groups consisting of a plurality of annular ribs extending concentrically around the apex at a predetermined distance from each other in the meridian direction, and on the outer peripheral side in the meridian direction from the apex. The diaphragm for an accumulator is characterized in that the annular rib is formed with greater rigidity in the rib group located in the position.

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