JPH0248711Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a piston seal structure for a compressor, and particularly to an improvement in the piston seal structure for a compressor that can contribute to improving the durability of the compressor.

[Conventional technology]

A compressor slides a piston inside a cylinder to discharge pressurized air to the outside, such as a tank. Conventionally, a piston ring is inserted into the piston body to ensure airtightness inside the cylinder. It is said that

The outer circumferential surface of the piston ring is brought into sliding contact with the inner wall surface of the cylinder to ensure sealing within the cylinder and to repeatedly discharge desired air pressure to the outside.

[Problem that the invention attempts to solve]

However, the piston ring installed in the piston generally has an abutment formed therein, and the existence of the abutment reduces the airtightness, that is, the sealing performance, within the cylinder, and the discharge amount of pressurized air, that is, the volumetric efficiency, deteriorates. There is a disadvantage. In order to prevent a significant drop in volumetric efficiency, a plurality of piston rings must be mounted on the piston, which inconveniently increases the number of parts and assembly steps.

Therefore, in view of the above-mentioned circumstances, the present invention improves the sealing performance at the sliding contact surface between the cylinder inner wall surface and the piston side, and maintains this improved sealing performance to improve the durability performance of the compressor. The purpose of this invention is to provide a new piston seal structure for a compressor.

[Means for solving problems]

In order to achieve the above purpose, the configuration of the present invention is as follows:
An endless tube having a dogleg-shaped cross section and a base and an upright portion is attached to the outer periphery of the tip of the piston body, which is disposed at the tip of the connecting rod inserted into the cylinder and is slidably housed in the cylinder. In addition to installing a piston seal, an O-ring is placed on the inner circumferential side of the piston seal, and the O-ring is pressed against the piston seal at the tip of the piston body, and the elastic force of the O-ring causes the piston seal to move in the axial direction. This feature is characterized by a fixing member press-fitted therein.

〔Example〕

Hereinafter, the present invention will be explained based on the illustrated embodiments.

FIG. 1 shows a compressor according to an embodiment of the present invention, in which a piston 1 is slidably housed in a cylinder 2 and is attached to the tip of a connecting rod 3. They are pin-coupled by a piston pin 4.
The rear end of the connecting rod 3 is
It is pivotally connected to a pin 5a implanted in one end of the crank 5. Further, the tip of a drive shaft 6 is connected to the center of the crank 5, and a gear 7 is connected to an intermediate portion of the drive shaft 6. and again,
A pinion gear 9 fixed to an output shaft 8a of a drive motor 8 meshes with the gear 7.

Therefore, by energizing the drive motor 8, the piston 1 slides in the direction shown by arrow X in the figure, and the pressure inside the cylinder 2 is discharged to the outside via the valve 2a.

Note that atmospheric air is sucked into the cylinder 2 through a check valve 1a provided in the piston 1.

As shown in FIG. 2, the piston 1 is pin-coupled to the connecting rod 3 by a piston pin 4 inserted through the intermediate body of the piston body 10, and the tip of the piston body 10 A piston seal 11 is provided on the outer periphery.
The piston seal 11 is formed in an annular shape with no joints or joints, that is, endless, and is attached to a notch 12 formed in an annular shape at the tip of the piston body 10. In addition,
The piston seal 11 is made of a material that has excellent wear resistance, low friction, heat resistance, and seizure resistance under oil-free conditions, such as polytetrafluoroethylene reinforced with carbon fiber or polytetrafluoroethylene reinforced with aromatic polyester. It is composed of fluoroethylene.

Further, the piston seal 11 is formed to have a dogleg shape in cross section, and an O-ring 13 is abutted on the inner peripheral side thereof. That is, the base 11a of the piston seal 11 is connected to the notch 12 of the piston body 10 by the O-ring 13.
The rising portion 11b of the piston seal 11 is energized by the O-ring 13 in a backed-up state so that its tip abuts against the inner wall surface of the cylinder 2. That is, the rising portion 11b of the piston seal 11 has its tip expanded toward the outer diameter side to form a so-called lip seal portion.

Note that the O-ring 1 fixing the piston seal 11 to the tip notch 12 of the piston body 10
3 is fixed with a resilient force by a fixing member 14 that is press-fitted into a notch 12 at the tip end of the piston body 10.

Therefore, when the piston 1 enters into the cylinder 2, the tip of the piston seal 11 comes into close contact with the inner wall surface of the cylinder 2, and high sealing performance is achieved. , and the inner wall surface of the cylinder 2 to allow gas to pass therebetween, thereby providing appropriate sliding properties.

Here, in the piston seal structure according to the present invention, the effect of interposing the O-ring 13 between the piston seal 11 and the fixing member 14 will be briefly explained.

That is, the piston seal 11 is connected to the piston body 10.
If the O-ring 13 is omitted and the fixing member 14 is press-fitted and fixed directly after being attached to the annular notch 12 at the tip of the piston seal, if the fixing force is excessive, the base 11a of the piston seal 11 may be compressed and deformed. This causes a significant expansion action in the outer diameter direction of the rising portion 11b, which increases the friction and impairs the slidability, and the piston seal 11
The fixing force may cause cracks in the base 11a, etc. of the piston seal 11, and there is a risk that the piston seal 11 may break or the sealing performance may be impaired.

Furthermore, if the fixing force is too small, the piston seal 11 will not be fixed within the annular notch 12, resulting in so-called looseness, resulting in a reduction in the compression stroke and occurrence of leakage from the inner diameter side of the piston seal 11. This has the disadvantage of reducing the volumetric effect.

Therefore, if an O-ring is inserted as in the present invention, when fixing the base of the piston seal within the annular notch at the tip of the piston body,
The fixing force is neither excessive nor insufficient, and there is no fear of cracking the piston seal.
Furthermore, there is no fear of rattling, and effective fixing can be performed.

Also, there is an O inside the rising part of the piston seal.
Since the ring is brought into contact and backed up, even if the outer periphery of the tip of the rising part is worn due to sliding contact with the inner wall of the cylinder, the inner wall of the cylinder and the outer periphery of the tip of the rising part are There are no gaps between the two, and there is no fear of leaks.

Furthermore, the piston seal only needs to be formed to a size that can be fixed within the notch, and there is an advantage that the dimensions of the piston seal itself can be easily controlled.

[Effect of idea]

According to the present invention, there are the following effects.

The piston seal provided on the outer periphery of the tip of the piston body is endless and has a dogleg-shaped cross section, so there is no gap in the piston seal itself, and moreover, during the penetration stroke, the tip of the rising part touches the inner wall of the cylinder. On the other hand, during the withdrawal stroke, the rising part bends toward the piston body and forms a gap between the piston seal and the inner wall of the cylinder, allowing gas to pass through. can.

The fixing member provided at the tip of the piston body can fix the O-ring disposed on the inner peripheral side of the piston seal with elastic force.

Since an O-ring is inserted on the inner circumference of the piston seal, the base of the piston seal can be fixed within the annular notch at the tip of the piston body, and the fixing force is neither too large nor too small. Therefore, effective fixing can be performed without worrying about the piston seal cracking or rattling.

Since the O-ring is in contact with the inside of the rising part of the piston seal and is backed up, even if the outer periphery of the tip of the rising part is worn due to sliding contact with the inner wall of the cylinder, the cylinder There is no gap between the inner wall of the tube and the outer periphery of the tip of the rising portion, and there is no fear of leakage.

It is sufficient that the piston seal is formed to a size that allows it to be fixed within the notch, and the dimensions of the piston seal itself can be easily controlled.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a compressor according to an embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view. 1... Piston, 2... Cylinder, 3... Connecting rod, 4... Piston pin, 10...
... Piston body, 11 ... Piston seal, 11
a...Base, 11b...Rising portion, 12...Annular notch, 13...O ring, 14...Fixing member.

Claims (1)

[Claims for Utility Model Registration] (1) A base and a An endless piston seal having a dogleg-shaped cross section with a rising portion is installed, and an O-ring is placed on the inner circumference of the piston seal, and the O-ring is pressed against the piston seal at the tip of the piston body. A piston seal structure for a compressor, characterized in that a fixing member is press-fitted to prevent the piston seal from moving in the axial direction due to elastic force. (2) The piston seal structure for a compressor according to claim 1, wherein the piston seal is made of polytetrafluoroethylene reinforced with carbon fiber. (3) The piston seal structure for a compressor according to claim 1, wherein the piston seal is made of polytetrafluoroethylene reinforced with aromatic polyester.