JPH0649801U - Accumulator piston - Google Patents

Abstract

(57) [Summary] [Purpose] High dimensional accuracy is achieved only by molding, high dimensional stability is maintained after molding, and it is possible to reduce costs by omitting cutting after molding, and it is lightweight. Provide an accumulator piston that can respond instantly to instantaneous changes in hydraulic pressure. [Structure] The accumulator 1 includes a cylinder 4 and a piston 5 that is slidably disposed inside the cylinder 4 and includes a cylinder portion 12 and a partition portion 13. The piston 5 is integrally formed of polyphenylene sulfide resin. A mounting strip 23 is integrally formed on the outer periphery of the cylindrical portion 12, and a seal lip 14 made of a thermoplastic elastomer is integrally formed on the outer periphery of the mounting strip 23 during one step of molding the cylindrical portion 12. Alternatively, the mounting groove may be formed on the outer circumference of the piston by the molding, and the O-ring may be fitted in the mounting groove.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an accumulator provided in a hydraulic circuit and used for absorbing pulsation and impact pressure and accumulating hydraulic energy, and particularly to the structure of a piston.

[0002]

[Prior art]

 As shown in FIG. 4, a piston 31 of a conventional accumulator provided in a hydraulic circuit of an automatic transmission of an automobile has a cylindrical tube portion 12 in which only the positive pressure side is expanded in a tapered shape, a positive pressure side and a back pressure side. The partitioning part 13 for partitioning is formed integrally by aluminum die casting.

A caulking portion 36 is cut on the peripheral portion of the partition portion 13 on the positive pressure side, and a spring supporting member 15 made of a steel disk is fixed to the positive pressure side by caulking the caulking portion 36. ing. A spring fixing portion 17 is curvedly formed on the inner peripheral edge of the spring supporting member 15, and a positive pressure side spring 16 is fixed to the spring fixing portion 17 at one end thereof. Further, a mounting groove 34 is cut on the outer periphery of each end portion on the positive pressure side and the back pressure side of the cylindrical portion 12, and a rubber O-ring 35 is fitted in the mounting groove 34.

[0004]

[Problems to be solved by the device]

 However, in order to manufacture the piston 31 and the like, the accumulator requires die cutting of the rough material and then cutting the end surface of the rough material and the mounting groove 34, which is time-consuming and time-consuming. The equipment cost and processing cost were too expensive. Further, the piston 31 is required to be further lightened in order to immediately respond to an instantaneous change in hydraulic pressure.

Therefore, recently, a lightweight piston has been developed which is injection molded from glass fiber reinforced nylon 66 resin. However, nylon 66 swells indefinitely due to moisture in the raw material and air (water swelling property), so the dimensional accuracy is insufficient with injection molding, and it is necessary to cut the mounting groove etc. after injection molding. there were. Moreover, the piston after cutting further swells due to the moisture in the air and the oil in the oil of the accumulator, so that the dimensional change occurs, and especially the diameter of the mounting groove becomes large. Therefore, even if the O-ring is fitted in the mounting groove, the tightening margin for the cylinder becomes too large, which is inappropriate. Therefore, it was necessary to fit a seal ring made of special synthetic resin with a notch into this mounting groove, and this seal ring was expensive.

The object of the present invention is to solve the above-mentioned problems, to have high dimensional accuracy only by molding, to maintain high dimensional stability after molding, and thus to reduce the cost by omitting the cutting process after molding. The aim is to provide a piston for an accumulator that can respond to instantaneous changes in hydraulic pressure due to its light weight.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the piston of the accumulator according to the first aspect has a structure formed by molding polyphenylene sulfide resin (PPS). This PPS has heat resistance, oil resistance, low shrinkage, and a linear expansion coefficient similar to that of a cylinder, but does not have water swellability. Further, PPS is appropriately reinforced by a well-known FRP (fiber reinforced resin) method such as mixing glass fibers in an amount of about 30 to 50% or mixing glass fibers and an inorganic filler in an amount of about 20 to 30%. I don't mind. Injection molding is the most common molding method.

[0008] Here, a seal portion that seals between the cylinder and the cylinder can be integrally formed on the outer periphery of the cylinder portion of the piston when the piston is molded. The "seal portion" may be integrally formed of the same material as the piston, or may be integrally formed of the piston and a different color material of two colors. As the shape of the seal portion, a lip shape, a wavy shape, an O-ring shape and the like can be exemplified.

Further, a mounting portion may be formed on the outer periphery of the cylindrical portion of the piston when the piston is molded, and a sealing member that seals between the mounting portion and the cylinder may be fitted. Examples of the shape of the “seal member” include a lip shape, a wavy shape, an O-ring shape, and the like. As the "mounting part", a groove, a line or the like fitted with the seal member can be exemplified. The piston of the accumulator according to claim 2 is one of these examples, and is configured such that an attachment groove formed by the molding is provided on the outer periphery of the piston, and an O-ring is fitted in the attachment groove. Is.

[0010]

[Action]

 The PPS of the accumulator piston according to claim 1 has a low shrinkage property and a linear expansion coefficient similar to that of the cylinder, and does not have a water swelling property, and therefore has high dimensional accuracy only by molding. However, high dimensional stability can be maintained after molding, and the cutting process after molding can be omitted to reduce costs. In addition, this piston is lighter in weight than the conventional one made of aluminum, and can respond instantly to changes in hydraulic pressure.

According to the piston of the accumulator of the second aspect, in addition to the above action, the mounting groove formed on the outer periphery of the piston by the molding has a high dimensional accuracy only by the molding, and after the molding, Since high dimensional stability is maintained, an inexpensive O-ring can be fitted and used even if it is not the special seal ring described above, and the sealability can be satisfied.

[0012]

【Example】

 An embodiment in which the present invention is embodied as an accumulator provided in a hydraulic circuit for reducing shift shock of an automatic transmission of a vehicle will be described with reference to FIG. The accumulator 1 of this embodiment is provided with a cylinder 4 formed in two stages of a large diameter portion 2 in the upper stage and a small diameter portion 3 in the lower stage, and a piston 5 slidably arranged in the cylinder 4. .

The cylinder 4 is sealed by a lid 6. The lid 6 is provided with a positive pressure side passage 7 opening into the cylinder 4, and the oil 10 from the shift valve 8 and the clutch 9 flows into the positive pressure side passage 7. At the lower end of the large-diameter portion 2 and the lower end of the small-diameter portion 3, a back pressure side passage 11 is opened to allow the oil 10 in the cylinder 4 to escape when the piston 5 slides to the back pressure side.

The piston 2 has a substantially cylindrical tubular portion 12 in which only the positive pressure side (upper part in FIG. 1) spreads in a tapered shape and the back pressure side (lower part in FIG. 1) has a uniform diameter, and the positive pressure side and the back pressure side. The partitioning part 13 for partitioning the space between and is formed integrally with PPS. Mounting ridges 23 are integrally formed on the outer circumferences of the upper end on the positive pressure side and the lower end on the back pressure side of the tubular portion 12, and a seal lip 14 made of a thermoplastic elastomer is formed on the outer circumference of the mounting ridge 23 when the tubular portion 12 is formed. It is integrally molded in one step. The seal lip 14 at the upper end on the positive pressure side slidably abuts on the inner wall of the large diameter portion 2 of the cylinder 4, and the seal lip 14 at the lower end on the back pressure side slidably abuts on the inner wall of the small diameter portion 3. Is designed to be sealed.

On the positive pressure side of the partition portion 13, there are arranged a spring support member 15 which is insert-molded when the piston 5 is molded and whose peripheral edge is fixed, and a positive pressure side spring 16 whose one end is supported by the spring support member 15. It is set up. The spring support member 15 is made of a steel disk, and is provided with a spring fixing portion 17 which temporarily raises the inner peripheral edge thereof in a curved shape and winds and fixes the lower end of the positive pressure side spring 16 on the inner peripheral edge. The upper end of the positive pressure side spring 16 contacts the inner wall of the lid body 6, and the positive pressure side spring 16 urges the piston 5 to the back pressure side. Further, a back pressure side spring 18 is arranged on the back pressure side of the partition portion 13, and the back pressure side spring 18 urges the piston 5 to the positive pressure side.

In the hydraulic circuit between the shift valve 8 and the accumulator 1, an orifice 19 for preventing an unnecessary amount of oil 10 from flowing to the clutch 9 side, and an oil supplied when the clutch 9 side is released. A check valve 20 is provided to allow the 10 to escape quickly.

Next, the operation of the accumulator 1 configured as described above will be described for the case where the shift valve 8 is operated during gear shifting of the vehicle and the hydraulic pressure supplied to the clutch 9 is momentarily increased. In this embodiment, the accumulator 1 is provided in the middle of the hydraulic circuit from the shift valve 8 to the clutch 9. Therefore, once the hydraulic pressure increase oil 10 is supplied to the positive pressure side of the accumulator 1 through the positive pressure side passage 7. Part of it flows in and slides piston 5 to the back pressure side. Since the piston 5 is made of PPS and is light in weight, it is possible to quickly respond to an instantaneous change in hydraulic pressure. Further, the same hydraulic pressure as that on the positive pressure side of the accumulator 1 acts on the clutch 9, and the positive pressure side spring 16, the back pressure side spring 18 and the hydraulic pressure acting on the positive pressure side of the accumulator 1 balance the accumulator 1 and the like. Smoothly changes the hydraulic pressure on the positive pressure side. That is, the oil pressure on the clutch 9 side is smoothly changed / supplied, the clutch 9 is gently engaged, and a variable speed shock is not generated in the vehicle body.

As described above, in the accumulator 1 of this embodiment, the spring support member 15 is insert-molded on the positive pressure side of the partition 13 in one step of molding the piston 5, so that the conventional spring support member is mounted. This eliminates the need for a piston cutting process and a caulking mounting process, and at the same time, the seal lip 14 is integrally molded, so the conventional piston cutting process for mounting the seal lip and the seal lip fitting process As a result, the number of manufacturing processes can be reduced and manufacturing equipment can be omitted. Further, since the piston 5 is made of PPS and is lighter in weight than the conventional one made of aluminum, it is possible to quickly respond to a momentary change in hydraulic pressure. Moreover, since PPS has a low shrinkage property and a linear expansion coefficient similar to that of the cylinder 4, and does not have a water swelling property, the piston 5 has high dimensional accuracy only by molding, and is high after molding. The dimensional stability can be maintained, and the cost can be reduced by omitting the cutting process after molding.

The present invention is not limited to the configuration of the above-described embodiment, and may be embodied by being arbitrarily modified within the scope not departing from the spirit of the invention as follows. (1) The seal lip 14 may have, for example, a ridge 21 having a triangular wave cross section as shown in FIG. 2, or may have a semicircular ridge 22 as shown in FIG. (2) The mounting strip 23 may be integrally formed on the outer periphery of the piston 5 when the piston 5 is molded, and the seal lip 14 formed separately from the mounting strip 23 may be fitted to the mounting strip 23 later. Also in this case, the cutting process of the piston 5 is not necessary, and the cutting equipment can be omitted.

[0020]

[Effect of device]

 As described in detail above, the piston of the accumulator according to claim 1 has high dimensional accuracy only by molding, and maintains high dimensional stability after molding, so that cutting process after molding is omitted and cost is reduced. It has the excellent effect of being able to reduce the pressure and being able to quickly respond to instantaneous changes in hydraulic pressure due to weight reduction.

According to the piston of the accumulator described in claim 2, in addition to the above effects, an inexpensive O-ring can be fitted and used even if it is not the above-mentioned special seal ring, and the sealability is improved. Can be satisfied.

[Brief description of drawings]

FIG. 1 is a sectional view of an accumulator according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another example of the seal lip.

FIG. 3 is a sectional view showing another example of the seal lip.

FIG. 4 is a cross-sectional view of a main part of a conventional accumulator.

[Explanation of symbols]

 1 Accumulator 4 Cylinder 5 Piston

Claims (2)

[Scope of utility model registration request] 1. A piston of an accumulator formed of polyphenylene sulfide resin. 2. A piston for an accumulator according to claim 1, wherein an attachment groove formed by the molding is provided on an outer circumference of the piston, and an O-ring is fitted in the attachment groove.