JP3190289B2 - accumulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a synthetic resin product, and more particularly to a synthetic resin product such as an accumulator formed of a synthetic resin.

[0002]

2. Description of the Related Art There is a conventional accumulator, particularly an accumulator piston, which is formed of aluminum. The technique disclosed in Japanese Patent Publication No. 6-88346 is disclosed as a technique for injection molding by changing the material to synthetic resin. Can be mentioned.

The technique disclosed in the above publication is a method of forming an accumulator piston by mixing glass fiber into a synthetic resin having a linear expansion coefficient within a predetermined range. An introduction groove for introducing the synthetic resin is provided on the front side or the back side, so that the flow of the glass fiber in the pressure receiving portion is substantially in one horizontal direction.

As a result, the flow of the glass fibers in the pressure receiving portion becomes unidirectional, the linear expansion coefficient of the pressure receiving portion becomes smaller than the linear expansion coefficient of aluminum, and the dimensional accuracy of the pressure receiving portion can be improved.

[0005]

Since the conventional synthetic resin product is configured as described above, when a spring pressure is applied to the pressure receiving portion from both sides and used, the outside of the pressure receiving portion outside the piston is used. Becomes a small-diameter coil spring, the load per unit area increases, the pressure-receiving part in the piston becomes a large-diameter coil spring, and a large stress is applied between the two, causing a reduction in dimensional accuracy.
Further, depending on the thickness of the pressure receiving portion, there is a possibility that the pressure receiving portion is deformed or broken due to the stress applied between both of the pressure receiving portions.

Further, since there is no detent such as undercut on the inner wall of the piston or the like, even if the annular plate or the like is brought into contact with the pressure receiving portion, the position of the spring is changed by the annular plate and the elastic coefficient can be changed accordingly. There is.

However, when the undercut detent is formed on the inner wall of the piston by cutting, if the inner wall is undercut, the relationship between the insertion position of the cutting tool and the cutting position is closer to the processing position than the insertion position. And the cost of the cutting process increases from the depth position.

As a method of forming an undercut on the inner wall of the piston, if the undercut is about 0.3 to 0.7 mm, it is possible to cope with forced undercutting.
However, since the mold is forcibly pulled out, the durability of the mold is shortened, and as a result, the cost is increased.

Accordingly, an object of the present invention is to provide an accumulator that eliminates the possibility that the elastic coefficient of the spring changes and reduces the load on the pressure receiving portion of the piston.

[0010]

According to a first aspect of the present invention, there is provided an accumulator having a substantially cylindrical accumulator piston inserted into a cylinder space formed by a case forming a cylinder and a cover sealing an opening of the case. In an accumulator which is displaced by pressure applied to both sides thereof, the accumulator piston has an undercut divided into a plurality of sections by forming a plurality of slits in a circumferential direction of an inner wall surface of the cylinder, and the undercut and the slit Formed in a concentric position, and a cylindrical projection that comes into contact with the cover to determine an initial position, and a pressure receiving portion in which a base of the cylindrical projection is aligned with a formation end of the undercut, The outer diameter side is
-Secured with a snap ring between the cut and the pressure receiving part
And an annular plate which is arranged between the forming end of the undercut and the pressure receiving portion, the inner diameter side of the annular plate
The end is fixed by expanding the pressure receiving part and the cap.
And a spring disposed between the bar .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an accumulator according to an embodiment of the present invention will be described.

FIG. 1 is a sectional view of a molding die for molding an accumulator piston according to a first embodiment of the present invention. FIG.
FIG. 3 is an explanatory view of an order in which a molding die for forming the accumulator piston according to the first embodiment of the present invention is drawn out, and FIG. 2 is an explanatory view of drawing out a slit forming die or the like for forming the accumulator piston, FIG. 3 is an explanatory diagram for drawing out an undercut mold for molding the accumulator piston. FIG. 4 is a plan view of the product as viewed from the upper surface (the right side in FIG. 1) of the accumulator piston according to the first embodiment of the present invention.

In the figure, a slide core 1 and a slide core 2 are molding dies for molding the periphery of an accumulator piston 20, and a fixed inner diameter core 3 is for molding the inside of the accumulator piston 20. The support plate 4 guides the slit forming die 11, and the mounting plate 5 mounts the support plate 4, various molds and the like. These function as known injection molding dies.

Further, in the present embodiment, the slit forming die 11 forms an inner wall of the accumulator piston 20 by:
It is slidable in parallel with the central axis of the accumulator piston 20 at a position divided into three equal parts of the circumference.
The slit forming die 11 forms a concave groove 22 of the accumulator piston 20 shown in FIG. Also, the inner cylinder core 13
Is concentric with the central axis of the accumulator piston 20 and is slidable in parallel with the central axis. The end portion of the inner cylindrical core 13 has a protruding portion 13a that protrudes a portion that is in sliding contact with an inner peripheral surface of the slit forming die 11 and an inner peripheral surface of the undercut forming die 12 described later, and has durability. It has a structure. In the present embodiment, the sliding portion at the end of the inner cylindrical core 13 is protruded to form the protruding portion 13a, but this has a structure in which the sliding portion has durability. This is not necessarily required when the present invention is implemented. The protruding portion 13a at the end of the inner cylindrical core 13 forms an annular groove 23 of the accumulator piston 20 shown in FIG.

The center core 14, which is concentric with the center axis of the inner core 13 and is slidable in parallel with the center axis, is slidable on the inner periphery of the inner core 13. . The center core 14 forms, together with the inner cylindrical core 13, a columnar projection 21 formed concentrically with the undercut. Further, the inner cylindrical core 13 releases the restriction on the inner peripheral surface of the undercut mold 12 described later, and allows the undercut mold 12 to move in the central axis direction.

In the present embodiment, the undercut forming die 12 is located at a position on the inner wall of the accumulator piston 20 which is divided into three equal parts of the circumference sandwiched between the slit forming dies 11, and the center of the accumulator piston 20. When the regulation of the inner peripheral surface of the undercut mold 12 is free to slide in parallel with the axis, the undercut mold 12 moves in the central axis direction. The undercut mold 12 is
Undercut 2 on inner wall of accumulator piston 20
The undercut forming die 12 formed with the undercut 24 is provided with an elastic force so as to move in the central axis direction of the undercut forming die 12 when the inner cylindrical core 13 is pulled out. The displacement distance is a distance at which the undercut mold 12 can slide freely in parallel with the central axis of the accumulator piston 20 without interfering with the undercut 24.

The accumulator piston 20 is formed as follows by the mold having the above-described configuration.

First, the slide core 1 and the slide core 2 for molding the periphery of the accumulator piston 20 and the fixed inner diameter core 3 for molding the inside of the accumulator piston 20 are set. The slit mold 11 and the undercut mold 12 are inserted up to predetermined positions, and the inner cylindrical core 13 and the center core 14 are inserted inside them. With the insertion of the inner cylinder core 13, the state changes from the state of being curved by the elastic force of the undercut mold 12 to the set state. In this state, the setting of the mold is completed.

Here, a molten synthetic resin for molding the accumulator piston 20 is injected and cooled in that state.
After cooling, as shown in FIG. 2, the slit forming die 11, the inner cylindrical core 13, and the center core 14 are connected to the accumulator piston 2.
Samples are taken out in parallel with the central axis of 0. At this time, the order of extracting the slit forming die 11, the inner cylindrical core 13, and the center core 14 may be the order of the slit forming die 11, the inner cylindrical core 13, and the center core 14, or the inner shape after extracting the slit forming die 11. The cylindrical core 13 and the center core 14 may be simultaneously extracted, or the slit mold 1
1. The inner cylindrical core 13 and the center core 14 may be simultaneously extracted. Usually, the slit mold 1
1. Pull out the inner cylindrical core 13 and the center core 14 in this order.

When the removal of the inner cylinder core 13 is completed, as shown in FIG. 3, the undercut molding die 12 is removed from the inner cylinder core 13 which has been restrained so far, so that the direction of the central axis of the undercut molding die 12 is reduced. The mold is released by its own elastic force, displaced, and moves to a position where it does not interfere with the formed undercut 24. In this state, the undercut forming die 12 is pulled out in parallel with the central axis of the accumulator piston 20, and the slide core 1 and the slide core 2 for forming the periphery of the accumulator piston 20, and the fixed die for forming the inside of the accumulator piston 20. The inner diameter core 3 is also released.

In the present embodiment, the molding of the accumulator piston 20 has been described. However, the present invention can be applied to any embodiment that forms an undercut on the inner peripheral surface.

As described above, the accumulator according to the present embodiment includes an outer die including the slide core 1, the slide core 2, the fixed inner diameter core 3 and the like, which form the outer shape of the product including the accumulator piston 20, and the outer die of the outer die. Located inside,
Undercut 2 divided into multiple parts in the circumferential direction of the inner wall of the cylinder
Mold 4 for forming an undercut 4 and a slit 2 for dividing the undercut 24 on the inner wall surface of the cylinder into a plurality of pieces.
2, a projecting portion 21 of the product is formed concentrically with the undercut forming die 12, and the base of the projecting portion 21 is made to coincide with the undercut forming end portion. Annular concave groove 2 that cuts into the product
3, the slit forming die 11 is pulled out after the injection molding, the inner cylindrical core 13 is drawn out, and the diameter of the undercut forming die 12 is reduced and then drawn out. .

Accordingly, when the undercut 24 is formed in the circumferential direction of the inner wall surface of the cylinder and the spring or the washer is fixed by the snap ring, or when the projections having different diameters are engaged with the undercut 24 to be removed. In the case of the stopper, the undercut 24 and the slit 22 of the inner wall surface of the cylinder can be easily formed, so that the inner wall and the like can be prevented from moving by the undercut 24, that is, the fixing means can be formed, thereby fixing the positions of the annular plate and the spring. it can. Naturally, the elastic coefficient does not change due to the difference in the mounting position.

Also, the inner cylindrical core 13 forming the annular concave groove 23 that cuts into the product is set at the molding position of the undercut mold 12 against the elastic force of the undercut mold 12. The inner surface of the undercut mold 12 and the tip of the inner core 13 are in sliding contact with each other each time the mold is set and released, and the wear of the tip of the inner core 13 affects the quality of the molded product. Become. However, the inner cylindrical core 13 having the annular concave groove 23 formed in advance into the product means that the protruding portion 13a is provided at the end of the inner cylindrical core 13, so that the quality of the product is affected. Molding can be continued without
The life of the mold can be extended.

In the above-described embodiment, the slit mold 11 and the inner cylindrical core 13 are configured independently of each other. However, when the present invention is implemented, both can be formed integrally.

The synthetic resin product comprising the accumulator piston 20 according to the present embodiment includes an outer mold comprising a slide core 1, a slide core 2, a fixed inner core 3 and the like which form the outer shape of the accumulator piston 20; An undercut mold 12 is formed inside the outer die and forms an undercut 24 divided into a plurality in the circumferential direction of the inner wall surface of the cylinder, and a slit 22 is formed to divide the undercut 24 of the inner wall surface of the cylinder into a plurality. Using the slit mold 11, pull out the slit mold 11 after injection molding,
Thereafter, the undercut mold 12 is formed by reducing the diameter and pulling it out.

Accordingly, when the undercut 24 is formed in the circumferential direction of the inner wall surface of the cylinder and the spring or the washer is fixed by the snap ring, or when the projections having different diameters are engaged with the undercut 24 to be removed. In the case of the stopper, the undercut 24 and the slit 22 of the inner wall surface of the cylinder can be easily formed, so that the inner wall and the like can be prevented from moving by the undercut 24, that is, the fixing means can be formed, thereby fixing the positions of the annular plate and the spring. it can. Naturally, the elastic coefficient does not change due to the difference in the mounting position.

The accumulator piston 20 thus formed is used as follows.

FIG. 5 is a sectional view of an accumulator using the accumulator piston according to the first embodiment of the present invention.

The case 40 forming the accumulator cylinder comprises a housing and the like disposed in a circuit used as a supplementary note of the hydraulic circuit. The cover 50 is a member that seals the opening of the cylinder of the case 40. The accumulator piston 20 is inserted into the cylinder space of the case 40. An O-ring groove 25 and an O-ring groove 26 are formed on the outer periphery of the accumulator piston 20, and an O-ring 27 and an O-ring 28 are mounted therein. Therefore, the space 44 formed by the case 40 and the pressure receiving portion 29 of the accumulator piston 20 communicates with the port 42 by the O-ring 27 and the O-ring 28.
And a space 45 communicating with the port 43 and formed by the case 40 and the side of the accumulator piston 20.
The space 44 is urged by a coil spring 61 in a direction to increase the volume.

The space 46 formed by the cover 50 and the pressure receiving portion 29 of the accumulator piston 20 is provided by the coil spring 64 which applies elastic force between the cover 50 and the pressure receiving portion 29 in the direction in which the volume is increased. I have. The coil spring 64 is integrally fixed by expanding the inner diameter side of a washer-shaped annular plate 62 formed by stamping a plate material on the inner diameter side. And the outer diameter of the annular plate 62 is
, One surface of the annular plate 62 is in surface contact with the surface of the pressure receiving portion 29 on the cover 50 side. However, annular groove 2
About 3 will be bridged.

The outer diameter of the annular plate 62 is held in a state where one surface of the annular plate 62 is in surface contact with the surface of the pressure receiving portion 29 on the cover 50 side by a snap ring 63 disposed inside the molded undercut 24. You. The snap ring 63 disposed inside the undercut 24 eliminates rattling of the annular plate 62 and can be firmly integrated. As a result, the snap ring 63 does not move in the surface direction of the pressure receiving portion 29, and the elastic coefficient does not change. Further, since the annular plate 62 equalizes the elastic force applied to the surface of the pressure receiving portion 29, a large elastic force is not locally applied.

Since the pressure receiving portion 29 is provided with elastic force from both sides as in the prior art, the cover 50 side of the pressure receiving portion 29 becomes a small-diameter coil spring 64 because of the configuration described above. The surface of the pressure receiving portion on the opposite side becomes a large-diameter coil spring 61, so that a large stress is not locally applied to a part of the pressure receiving portion 29, and the dimensional accuracy of the pressure receiving portion 29 of the accumulator piston 20 is reduced. There is no. Further, there is no possibility that the pressure receiving portion 29 is deformed or broken due to the stress applied between both of the pressure receiving portions 29.

The accumulator according to the embodiment of the present invention includes a case 40 forming a cylinder and its case 4.
A cylindrical accumulator piston 20 inserted into a cylinder space formed by a cover 50 that seals the opening
However, in the accumulator which is displaced by the pressure difference applied to both sides thereof, the accumulator piston 20
An undercut 24 formed by dividing the inner wall surface of the cylinder into a plurality in the circumferential direction; a cylindrical projection 21 formed concentrically with the undercut 24 and in contact with the cover 50 to determine an initial position; A pressure receiving portion 29 in which a base for forming the columnar projecting portion 21 is aligned with an end for forming the undercut 24;
An annular plate 62 is provided between the end of the undercut 24 and the pressure receiving portion 29, and a coil spring 64 is provided between the annular plate 62 and the cover 50.

Therefore, when an elastic force is applied to the pressure receiving portion 29 from both sides and used, the cover 50 side of the pressure receiving portion 29 of the accumulator piston 20 becomes a small-diameter coil spring 64, and the weight per unit area increases.
Pressure receiving portion 2 of case 40 side of accumulator piston 20
Even if the coil spring 9 is a large-diameter coil spring, the undercut 24 is formed in the circumferential direction of the inner wall surface of the cylinder and is fixed via the annular plate 62. The weight distribution of the coil spring 64 can be reduced, and the dimensional accuracy does not decrease due to local stress between the two. Further, even if the thickness of the pressure receiving portion 29 is reduced, the weight of the elastic force applied to the pressure receiving portion 29 per unit area is reduced, and the possibility of deformation or breakage due to stress can be eliminated.

Since the undercut 24 and the slit 22 on the inner wall surface of the cylinder can be easily formed, the inner wall and the like can be prevented from moving by the undercut 24, that is, the fixing means can be formed. The position can be fixed, and naturally the elastic coefficient does not change due to the difference in the mounting position.

Since the undercut 24 can be formed on the inner wall or the like of the accumulator piston 20, the annular plate 62 is brought into surface contact with the pressure receiving portion 29, and the position of the coil spring 64 can be fixed by the annular plate 62, and the elastic coefficient can be changed. There is no sex.

Further, the cylindrical projection 21 of the accumulator piston 20 can restrict the movement of the accumulator piston 20 by contacting the surface of the cover 50, and the contact position between the projection 21 and the cover 50, that is, the projection The surface 21 can be used as a reference surface. Therefore, since the limit of the movement of the accumulator piston 20 can be set by the projection 21, the neutral position of the accumulator piston 20 can be easily set.

In the present embodiment, the annular plate 6
2, the coil spring 64 is fixed, so that accurate and stable operation can be expected.

In the present embodiment, the annular plate 6
2, the coil spring 64 on the cover 50 side is fixed, but the coil spring 61 can also be used.

[0041]

As described above, according to the accumulator of the first aspect, the accumulator piston has an undercut formed by dividing the cylindrical inner wall surface into a plurality in the circumferential direction.
A cylindrical projection formed concentrically with the undercut and abutting against the cover to determine an initial position, and a pressure receiving portion in which a base forming the columnar projection matches the formation end of the undercut. And an annular plate disposed between the end of the undercut and the pressure receiving portion, and a spring disposed between the annular plate and the cover.

Therefore, the undercut is formed in the circumferential direction of the inner wall surface of the cylinder, and the small-diameter coil spring is fixed via the annular plate. Therefore, the weight distribution of the small-diameter coil spring can be reduced, and the local portion between the two can be reduced. The pressure receiving portion does not lower the dimensional accuracy due to the mechanical stress. Further, the possibility of deformation or breakage due to stress can be eliminated. And, since undercuts and slits on the inner wall surface of the cylinder can be easily formed, detents by the undercuts on the inner wall and the like, that is, fixing means can be configured,
Thereby, the positions of the annular plate and the coil spring can be fixed, and the elastic coefficient does not change due to the difference in the mounting position. Furthermore, the movement of the projecting portion of the accumulator piston can be restricted by contacting the surface of the cover, and the surface of the projecting portion can be used as a reference surface.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding die for molding an accumulator piston according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing that a slit forming die for forming an accumulator piston according to the first embodiment of the present invention has been pulled out.

FIG. 3 is an explanatory diagram for drawing out an undercut mold or the like for molding the accumulator piston according to the first embodiment of the present invention.

FIG. 4 is a plan view of an accumulator piston according to the first embodiment of the present invention.

FIG. 5 is a sectional view of an accumulator using an accumulator piston according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Slit molding die 12 Undercut molding die 13 Inner cylinder core 20 Accumulator piston 21 Projection part 22 Slit 23 Depression groove 24 Undercut 29 Pressure receiving part 40 Case 50 Cover 62 Ring plate 64 Coil spring

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-209201 (JP, A) JP-A-2-278001 (JP, A) JP-A 8-109901 (JP, A) JP-A 8- 72105 (JP, A) JP-A-3-20101 (JP, A) JP-A-6-82404 (JP, U) JP-A-6-49801 (JP, U) JP-A-62-158234 (JP, U) WO 93/23229 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F15B 1/24

Claims (1)

(57) [Claims] An accumulator in which a substantially cylindrical accumulator piston inserted into a cylinder space formed by a case forming a cylinder and a cover sealing an opening of the case is displaced by a pressure applied to both sides thereof. The accumulator piston is formed into a plurality of slits in the circumferential direction of the inner wall surface of the cylinder and formed into a plurality of divided undercuts, and is formed at a concentric position with the undercuts and the slits, and abuts on the cover. A columnar protrusion for determining the initial position, a pressure receiving portion in which the base for forming the columnar protrusion is aligned with the formation end of the undercut, and a plurality of undercuts on the outer diameter side and the pressure reception. Between departments
In fixed with a snap ring, and an annular plate which is arranged between the forming end of the undercut and the pressure receiving portion, the end portion by expanding the inner diameter side of the annular plate
An accumulator, comprising: a spring fixed and disposed between the pressure receiving portion and the cover .