JP4274953B2 - Resin piston for vehicle actuator and manufacturing method thereof - Google Patents

Description

  The present invention relates to a resin piston used for an actuator such as a master cylinder or a slave cylinder, which is used to operate a brake or a clutch of a vehicle, and a manufacturing method thereof, and in particular, has a recess on one end central axis of a shaft portion. In addition, the present invention relates to a resin piston having a flange portion at one end thereof and a manufacturing method thereof.

  Conventionally, in a tandem hydraulic master cylinder, a primary piston and a secondary piston, a cup-shaped cup that movably accommodates a guide pin protruding from the front end of the primary piston and a guide pin attached to the rear end of the secondary piston. It is connected with the retainer. The secondary piston has a guide pin escape recess on one end central axis of the shaft portion, and a flange portion on which the retainer is mounted at one end.

This piston is formed by injecting molten resin into a cavity formed by a plurality of molds having a molding surface corresponding to the outer peripheral shape of the piston. The mold is a mold that forms the outer shape of the piston. And a core for forming a recess formed at the piston end, and a gate for injecting molten resin into the core is formed, from which the molten resin is injected into the cavity to form a piston. (For example, refer to Patent Document 1).
JP 2002-137256 A

  However, in the above case, when molten resin is injected from the gate into the cavity, the molten resin directly projects into the back of the cavity, and the molten resin is filled and solidified from the back, so the resin flow is uneven. As a result, jetting occurs, the dimensions of the molded piston are not stable, and voids and shrinkage may occur.

  Therefore, the present invention can sequentially fill the molten resin from the one end side having the cavity gate to the other end side in an orderly manner, prevents the occurrence of jetting, has high dimensional accuracy, and is free from voids and shrinkage. It aims at providing the good resin piston which is not, and also aims at providing the manufacturing method.

In order to achieve the above object, according to a first aspect of the present invention , a large-diameter shaft portion is continuously formed behind a small-diameter shaft portion, and a first flange portion to which a first cup seal is fitted is provided on the large-diameter shaft portion. A second flange portion that fits the second cup seal at the front end is on the rear end side of the intermediate portion, and a third flange portion that supports the retainer on a guide rib that is provided around one end surface on the piston rear portion side is on the rear end. is formed, said end surface resin piston actuator for a vehicle recesses on the central axis is formed, to injecting a molten resin in the central axis direction of a plurality of gates provided in a portion forming the end face Ruki It is characterized by injection molding with Cavity.

In the second invention, the one end face of the third flange portion, and a gate mark is characterized by the formation of the gate relief recess for preventing the projected from the one end surface.

In the third aspect of the invention, a large-diameter shaft portion is continuously formed behind the small-diameter shaft portion, and a first flange portion to which a first cup seal is fitted is provided at the tip of the large-diameter shaft portion. A second flange portion for fitting the seal is formed on the rear end side of the intermediate portion, and a third flange portion for supporting the retainer on a guide rib provided around one end surface on the piston rear side is formed on the rear end. In the resin piston manufacturing method for a vehicle actuator in which a concave portion is formed on the central axis, the plurality of gates provided in a portion for molding one end face of the third flange portion of the cavity formed by a plurality of molds the central axis direction to the molten resin is characterized in that molded out morphism in the cavity.

In the fourth aspect of the invention, a large-diameter shaft portion is continuously formed behind the small-diameter shaft portion, and a first flange portion to which a first cup seal is fitted is provided at the tip of the large-diameter shaft portion. A second flange portion for fitting the seal is formed on the rear end side of the intermediate portion, and a third flange portion for supporting the retainer on a guide rib provided around one end surface on the piston rear side is formed on the rear end. In the resin piston manufacturing method for a vehicle actuator in which a concave portion is formed on the central axis, the plurality of gates provided in a portion for molding one end face of the third flange portion of the cavity formed by a plurality of molds while leaving shot an axial direction to the molten resin into the cavity, and the molten resin is characterized in that molding is filled into the cavity while colliding with the cavity inner face of the gate near.

According to a fifth aspect of the invention, the cavity inner surface that collides with the molten resin is a portion that forms the other end surface of the third flange portion of the cavity.

  According to the first invention described above, it is possible to prevent the occurrence of jetting at the time of molding, and it is possible to obtain a good resin piston having high dimensional accuracy and free from voids and shrinkage.

  According to the second invention, the gate mark does not protrude from the end face of the flange portion, and the member to be mounted on the end face can be satisfactorily attached without being obstructed by the gate mark.

  According to the third invention, the molten resin can be filled in order from the one end side provided with the gate of the cavity to the other end side in order, the occurrence of jetting is prevented, the dimensional accuracy is high, and voids and A good resin piston without shrinkage can be obtained.

  According to the fourth and fifth inventions, the molten resin injected from the gate is introduced into the cavity while colliding with the portion forming the other end face of the flange portion of the cavity and the inner surface of the cavity near the gate. Since it is filled in order from one end side with the other gate toward the other end side, jetting can be prevented, dimensional accuracy is high, and a good resin piston without voids or shrinkage Can be obtained.

  Hereinafter, an embodiment in which the present invention is applied to a piston of a conventional hydraulic master cylinder will be described in detail with reference to the drawings.

  The resin piston 1 has a small-diameter shaft portion 1a formed at the tip, and a large-diameter shaft portion 1b formed continuously behind the small-diameter shaft portion 1a. The large-diameter shaft portion 1b is formed with a first flange portion 2 at the front end, a second flange portion 3 at the rear end side of the intermediate portion, and a third flange portion 4 at the rear end. The portion 3 is formed to have a diameter substantially equal to the inner diameter of the cylinder hole 5, and the third flange portion 4 is formed to have a smaller diameter. The large-diameter shaft portion 1b between the first flange portion 2 and the second flange portion 3 is formed with a plurality of ribs 6 in the axial direction, and the rear end portion of the large-diameter shaft portion 1b has a recess 7 on the central axis. Is formed. A taper portion 2a that gradually decreases in diameter toward the rear side of the piston is formed at the rear portion of the first flange portion 2, and a taper portion 3a that gradually decreases in diameter toward the front portion of the piston at the front portion of the second flange portion 3 respectively. Is formed.

  The front portion of the third flange portion 4 is formed with a tapered portion 4a having a gradually decreasing diameter toward the piston front portion side, and a guide rib 4c is provided on the inner peripheral side of the end surface 4b on the piston rear portion side. Yes. The one end face 4b is provided with three gate relief recesses 4d at equal intervals in the circumferential direction. The depth of each recess 4d is formed so that the three gate marks 8 generated when the molten resin is injected into the cavity at the time of piston molding do not protrude from the one end face 4b of the third flange portion 4.

  The resin piston 1 as described above is integrally molded by a molding die 10 as shown in FIG. 3 using a synthetic resin as a material. The mold 10 includes a tip-side split mold 11 that forms from the piston tip to the large-diameter portion of the first flange portion 2, and a rear end of the taper portion 4 a of the third flange portion 4 from the taper portion 2 a of the first flange portion 2. The middle upper side split mold 12 that forms the upper part in FIG. 3, the middle lower side split mold 13 that forms the lower part from the tip of the tapered part 2a to the rear end of the tapered part 4a of the third flange part 4, and the third flange The rear end side split mold 14 that forms from the portion 4 to the piston rear end portion and the core 15 that forms the recess 7, and the five split molds 11, 12, 13, 14 formed in this way, A cavity 16 for piston molding is formed in the interior where the core 15 is abutted.

  The cavities 16 formed in this way are provided with gates 18 through which molten resin is injected via sprues 17 in the three gate relief recess 4d molded portions of the rear end side split mold 14, respectively. Molten resin is injected from 18 and filled into the entire cavity 16. At this time, the molten resin is filled into the cavity 16 while colliding with the forming surface 12a that forms the other end surface 4e of the third flange portion 4 of the cavity 16. As a result, the molten resin is quickly filled in order from the one end provided with the gate 18 of the cavity 16 toward the other end, so that no jetting occurs, and the molded product does not occur. There is no risk of voids or shrinkage.

The molten resin filled in the cavity 16 in this way has a small-diameter shaft portion 1a, a large-diameter shaft portion 1b, first to third flange portions 2, 3, 4, ribs 6, and a concave portion 7 integrally. As shown in FIG. 4, the piston 1 becomes a high piston 1, and three gate marks 8 are formed in the gate escape recess 4 d on the one end surface 4 b of the third flange portion 4. It is applied as a secondary piston of a conventional hydraulic master cylinder 20.

  The hydraulic master cylinder 20 includes a primary piston 22 and the secondary piston 1 inside a cylinder hole 5 formed in a cylinder body 21, and a first hydraulic chamber 23 is provided between the pistons 22, 1. In a two-system tandem type in which a second hydraulic chamber 24 is defined between the bottom of the hole 5 and the secondary piston 1, hydraulic fluid is supplied from each hydraulic chamber 23, 24 to a wheel cylinder (not shown).

  A primary boss 25 and a secondary boss 26 project from the upper portion of the cylinder body 21, and a reservoir 27 that stores hydraulic fluid in the liquid storage chamber 27 a is integrally attached via the boss portions 25 and 26. Yes. The reservoir 27 has a first boss portion 28 and a second boss portion 29 projecting from the lower surface thereof, and the boss portions 28 and 29 are respectively fitted to the primary boss 25 and the secondary boss 26, and further between them. Reservoir 27 is integrally connected to the upper part of cylinder body 21 by screwing screws onto both overlapping attachment pieces 30, 31.

  The primary piston 22 has a flange portion 32 that is substantially equal to the inner diameter of the cylinder hole 5 on the outer peripheral front end side of the body portion. A cup seal 33 is fitted on the piston front end side surface of the flange portion 32, and the rear end of the body portion Is formed with a receiving hole 22a for a push rod. The primary piston 22 is restricted by the closing member 34 from moving backward.

  In the secondary piston 1, a cup seal 35 is fitted on the piston front side surface of the first flange portion 2 described above, and between the piston rear end side surface of the second flange portion 3 and the piston front end side surface of the third flange portion 4. A cup seal 36 is fitted. The primary piston 22 and the secondary piston 1 are connected by a guide pin 37 protruding from the tip of the primary piston 22 and a cup-shaped retainer 38 that is attached to the rear end of the secondary piston 1 and movably accommodates the guide pin 37. Has been.

  The retainer 38 is configured such that the inner peripheral surface of the opening side is supported by the guide rib 4c of the third flange 4, and the flange portion 38a formed at the opening end is attached to the one end surface 4b of the third flange portion 4 of the secondary piston 1. Installed. At this time, each gate mark 8 formed on the one end face 4b of the third flange portion 4 is disposed in the gate escape recess 4d and does not protrude from the one end face 4b of the third flange portion 4. 38 can be attached well.

  A first replenishing fluid chamber 39 is defined between the cup seal 33 provided on the primary piston 22, the closing member 34, and the cylinder hole 5, and the rear end of the cup seal 33 of the primary piston 22 and the secondary piston 1. The first hydraulic chamber 23 is defined between the side cup seal 36 and the cup seal 36. Further, a second replenishing liquid chamber 40 is defined between the cup seals 35 and 36 of the secondary piston 1 and the cylinder hole 5, and the cup seal 35 on the tip side of the secondary piston 1 and the bottom of the cylinder hole 5 are defined. In the meantime, the second hydraulic chamber 24 is defined. A first return spring 41 is provided in the first hydraulic pressure chamber 23, and a second return spring 42 is provided in the second hydraulic pressure chamber 24 in a contracted manner. 1 is biased toward the cylinder hole opening side. The cylinder hole 5 has, on its upper peripheral wall, a first supply port 43 communicating with the first replenishing liquid chamber 39 and the inside of the first boss portion 28 of the reservoir 27, a first hydraulic pressure chamber, and a first boss portion of the reservoir 27. 28, a second relief port 44 that communicates with the interior of the interior 28, a second supply port 45 that communicates with the interior of the second boss portion 29 of the second replenishment fluid chamber 40 and the reservoir 27, and a second relief port 44 that communicates with the second fluid pressure chamber and the reservoir 27. The 2nd relief port 46 connected to the inside of 2 boss | hub part 29 is penetrated and formed.

  When the primary piston 22 and the secondary piston 1 are not in operation, the primary piston 22 and the secondary piston 1 are disposed at the positions shown in FIG. 4 by the elastic force of the return springs 41 and 42, and the first hydraulic pressure chamber 23 is connected to the first supply port 43. The second hydraulic pressure chamber 24 communicates with the liquid storage chamber 27a of the reservoir 27 via the second replenishing liquid chamber 40 and the second supply port 45, respectively. .

  When the push rod pushes the primary piston 22 during operation, the primary piston 22 advances the cylinder hole 5 toward the bottom while compressing the first return spring 41 in the first hydraulic pressure chamber 23, and the cup seal of the primary piston 22. After 33 passes through the first relief port 44, the communication between the first hydraulic pressure chamber 23 and the liquid storage chamber 27a of the reservoir 27 is blocked, thereby generating a hydraulic pressure in the first hydraulic pressure chamber 23. The hydraulic fluid boosted in the first hydraulic chamber 23 is supplied to one brake system via the discharge port of the cylinder body 21. On the other hand, simultaneously with the advancement of the primary piston 22, the secondary piston 1 starts to advance toward the bottom of the cylinder hole, and after the cup seal 35 of the secondary piston 1 passes through the second relief port 46, the second hydraulic pressure chamber 24. As a result, the fluid pressure is generated in the second fluid pressure chamber 24. The hydraulic fluid boosted in the second hydraulic pressure chamber 24 is supplied to the other brake system via the discharge port of the cylinder body 21. When the braking is released, the primary piston 22 and the secondary piston 1 are returned to their initial positions by the return springs 41 and 42.

  The present invention is not limited to the resin piston used for the conventional type master cylinder as in the above-described embodiment, but can also be applied to the resin piston used for the center valve type master cylinder, The present invention can also be applied to resin pistons used in master cylinders and slave cylinders for clutches.

The perspective view of the resin piston which shows the 1st form example of this invention Same side view Illustration of resin piston molding Cross section of the main part of a hydraulic master cylinder equipped with a resin piston

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Resin piston, 1a ... Small diameter shaft part, 1b ... Large diameter shaft part, 2 ... 1st flange part, 3 ... 2nd flange part, 4 ... 3rd flange part, 2a, 3a, 4a ... Tapered part, 4b ... One end face, 4c ... guide rib, 4d ... gate relief recess, 4e ... other end face, 5 ... cylinder hole, 6 ... rib, 7 ... recess, 8 ... gate mark, 10 ... molding die, 11 ... tip side split die, 12 ... Middle upper side split type, 12a ... forming surface, 13 ... middle lower side side split type, 14 ... rear end side split type, 15 ... core, 16 ... cavity, 17 ... sprue, 18 ... gate, 20 ... hydraulic master cylinder , 21 ... Cylinder body, 22 ... Primary piston, 23 ... First hydraulic chamber, 24 ... Second hydraulic chamber, 27 ... Reservoir, 33, 35, 36 ... Cup seal

Claims (5)

A large-diameter shaft portion is continuously formed behind the small-diameter shaft portion, and a first flange portion to which a first cup seal is fitted is fitted to the distal end of the large-diameter shaft portion, and a second cup seal is fitted to the distal end. A second flange portion is formed on the rear end side of the intermediate portion, and a third flange portion that supports the retainer is formed on the guide rib that is provided around one end surface on the piston rear portion side, and a recess is formed on the central axis of the one end surface. vehicle, characterized in that but a resin piston actuator for a vehicle is formed, and the central axis direction to the molten resin from a plurality of gates provided in a portion forming the end face by injection molding at an injection to Ruki Yabiti Actuator resin piston. Wherein on the one end face of the third flange portion, a vehicle resin piston actuator according to claim 1, wherein the gate mark forming a gate escaping recess for preventing the projected from the one end surface. A large-diameter shaft portion is continuously formed behind the small-diameter shaft portion, and a first flange portion to which a first cup seal is fitted is fitted to the distal end of the large-diameter shaft portion, and a second cup seal is fitted to the distal end. A second flange portion is formed on the rear end side of the intermediate portion, and a third flange portion that supports the retainer is formed on the guide rib that is provided around one end surface on the piston rear portion side, and a recess is formed on the central axis of the one end surface. In the resin piston manufacturing method for an actuator for a vehicle in which is formed , melting is performed in the direction of the central axis from a plurality of gates provided in a portion for molding one end face of the third flange portion of a cavity formed by a plurality of molding dies. resin piston manufacturing method for a vehicle actuator, which comprises molding a resin out morphism in the cavity. A large-diameter shaft portion is continuously formed behind the small-diameter shaft portion, and a first flange portion to which a first cup seal is fitted is fitted to the distal end of the large-diameter shaft portion, and a second cup seal is fitted to the distal end. A second flange portion is formed on the rear end side of the intermediate portion, and a third flange portion that supports the retainer is formed on the guide rib that is provided around one end surface on the piston rear portion side, and a recess is formed on the central axis of the one end surface. In the resin piston manufacturing method for an actuator for a vehicle in which is formed , melting is performed in the direction of the central axis from a plurality of gates provided in a portion for molding one end face of the third flange portion of a cavity formed by a plurality of molding dies. while leaving morphism resin in the cavity, the resin of a vehicle actuator, characterized in that the molten resin is molded by filling the cavity while colliding with the cavity inner face of the gate near the piston Manufacturing method. 5. The resin piston manufacturing method for a vehicle actuator according to claim 4, wherein an inner surface of the cavity with which the molten resin collides is a portion forming the other end surface of the third flange portion of the cavity.

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