JPS5824681Y2 - Oil-free sealing device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a reciprocating oil-free sealing device suitable for sealing air cylinders and the like.

Conventionally, air cylinder seals have a U seal (first
(Figure), It is uneconomical.

The processing cost for two grooves 2 is required, making the entire device expensive.

In addition, if the seal is not properly lubricated, the seal will run out of oil and the life of the seal will be shortened.

3 is the inner surface of the cylinder, and 4 is a reciprocating piston fitted inside the cylinder.

In the X-ring 5 shown in Fig. 2, the annular protrusions 6, 6 with a V-shaped cross section that open toward the cylinder inner surface 3 facing the groove 2 are all curved when viewed from the cross section of Fig. 2, so this is due to the structure of the mold. The mating surface is a curved part, which requires high precision in mold manufacturing and is difficult to measure.

Moreover, since there is a mold mating surface in the sealing part, there is variation in sealing performance especially at low pressures.

Since the contact area of the sliding portion with the inner surface of the cylinder is larger than that of the U-packet, the sliding resistance and its variation are also large.

Furthermore, since the protrusions 6, 6, which function as lips, have a large wall thickness and therefore have a small tensioning margin, it is necessary to improve the dimensional accuracy of the groove 20.

Since the pocket area of the grease reservoir 7 formed between both protrusions 6 and the cylinder inner surface 3 is small, the amount of grease is limited, and there is a drawback that oil runs out easily and the service life is shortened.

Since the O-ring 8 shown in FIG. 3 does not have a grease reservoir, it requires oiling and has a large sliding resistance.

Since the sliding resistance varies greatly depending on the crushing amount, it is necessary to improve the dimensional accuracy of the groove 2 in order to always obtain stable sliding resistance.

It also has a short lifespan. This invention is based on the above U packing, X ring, O
The purpose is to provide a long-life, oil-free seal with low sliding resistance that compensates for the drawbacks of each ring, and examples thereof are shown in FIG. 4 and subsequent figures.

Figure 4 is for internal and external use, Figure 5 is for external use, and Figure 6 is for inner tank use.The solid line shows the cross-sectional shape of the oil-free seal according to the present invention in the free state, and is an annular groove with a rectangular cross section, 3 is the inner surface of the cylinder, 10 is the shaft, and O is the shaft center line. For convenience of drawing, this shaft center line O is drawn near the groove 2, but in reality it is further away. Specifically, when the groove width dimension L1 is 7 mm, the groove bottom diameter dls and the cylinder inner diameter Dl are, for example, d.
, ~ When 30 fights D1 = 40 fights, dl = 90 fights I) 1
=100mm.

The oil-free seal 11 shown in FIG. 4 has a pair of annular rings that open from the center of the seal body 12 and have a V-shaped cross section with respect to the cylinder inner surface 3 facing the seal mounting groove 2 and abut against each other to form a grease reservoir. The lip portion 13 has a cross section L2 that gradually decreases toward the tip, and the tip has an annular projection having a small arcuate cross section that comes into contact with the cylinder inner surface 3 and exerts a sealing effect. 18, and a cylindrical portion 15 having a diameter approximately equal to that of the mounting groove shoulder 14, and an annular side end surface 16 parallel to the side wall 2a of the groove 2.
A part of the stopper formed by the above is provided adjacent to the annular protrusion 18, and further below the seal body 12 is elastically pressed against both side walls 2a of the groove bottom when installed in the annular groove 2, as shown in FIG. 4a. L is provided with a seal stable bottom part 131,
・Ru.

The length L3 of the cylindrical portion 15 is such that when the piston 4 reciprocates in the direction of arrow A-A with respect to the cylinder inner surface 3 in the mounted state shown in FIG. ), and the radius of curvature R of the cross section of the annular projection 18 in its free state is determined to be small enough to allow the projection 18 to perform a flexible sealing action. .

In the case of the above specific example in which the groove width dimension L1 is 7 mm, the cylindrical portion 15
The length L3 is 0.2 to 0.5 mm1, preferably 0.3
The height L4 of the annular projection 18 is approximately 0.1 to 0.5 mm, preferably 0.2 mm, and the height L4 is approximately 0.2 to 0.5 am, preferably approximately 0.3 mm.

As shown in Fig. 4a, an oil-free seal 11 according to the present invention is installed in the groove 2.
, and seal the stable bottom part 131 on both side walls 2a of the groove bottom.
are pressed against each other to prevent the seal body 12 from moving in the axial direction,
When grease is sealed in the grease reservoir 17 and the piston 4 is reciprocated in the direction of the arrow with respect to the inner surface of the cylinder 3 while leaving a gap between the annular end surfaces 16 of the lip portion 13 and the groove side wall 2a. For example, when the piston 4 moves in the direction of arrow A, the right cylindrical portion 15 is approximately flush with the groove shoulder 14, so the annular projection 18 is prevented from engaging with the gap 19,
The annular protrusion 18 is supported from behind by the thick lip portion 13 and comes into pressure contact with the cylinder inner surface 3, and since its radius of curvature R is an arcuate cross section that is sufficiently small, it acts as a dual-acting, non-directional lip seal. .

The grease in the grease reservoir 17 is automatically supplied to the sliding surface between the annular projection 18 and the cylinder inner surface 3 due to its inertia.

Of course, the annular protrusion on the left also acts as a dual-function lip seal.

When the piston 4 moves in the direction of arrow A, the cylindrical portion on the left side prevents the annular projection on the left side from being bitten.

The seal structure of the seals shown in FIGS. 5 and 6 is the same.

However, a pair of annular protrusions 22 are integrally provided on the bottom surface 21 of the seal stable bottom portion 231 in FIG. 5 to improve sealing performance.

Of course, the bottom surface 21 can also be tapered as shown in 21', or can be provided with a number of annular protrusions with serrated cross-sections.

Reference numeral 23 in FIG. 6 is an annular protrusion that functions similarly to the protrusion 22 in FIG.

The effects of this invention are as follows.

(1) Since the annular projection 18, which is a sealing portion, has a small circular arc shape, sliding resistance is low and the life is long.

That is, since the contact area with the contact surface is smaller than that of the X-ring and O-ring, which have a large circular arc shape, the sliding resistance is small.

In addition, the wear resistance of the seal portion is improved compared to an edge-shaped seal portion, resulting in a longer life, and since there is no catching on the sliding surface, stick-slip is less likely to occur.

(2) The presence of the cylindrical portion 15 can prevent the arcuate protrusion 18 from being caught in the gap 19 between the groove shoulder portion 14 and the sliding surface even under high pressure.

(3) Since the annular protrusion 18 is provided adjacent to the end surface of the groove side wall, the grease reservoir 17 can be larger than the X-ring, and can be used for a long period of time without replenishing grease.

(4) Compared to the XIJ ring, it can have a more flexible lip structure, so there is no need to increase the precision of groove processing.

(5) Since there is no mold mating surface on the sealing surface, the sealing performance is stable, especially at low pressures.

(6) Since the product size can be made compact, the packaging has no directionality and can be made compatible with the U packaging.

(7) In the present invention, since the seal main body 12 installed in the annular groove 2 with a rectangular cross section is provided with the seal stable bottom portions 131, 131 that elastically press against the both side walls 2a of the groove bottom when installed, When the piston 4 reciprocates in the left and right (arrows A, A) direction, the seal body 12 can be prevented from moving in the axial direction, and when stopped, the annular side end surfaces 16 and side walls of the pair of annular lips 13 A small gap can be accurately maintained between the pistons 2a, and when the piston 4 reciprocates left and right, the annular protrusion 18 effectively exhibits a sealing function in either direction.

That is, as shown in Fig. 4a, the piston 4 is on the left (in the direction of arrow A).
When moving, the lip portion 13 receives a clockwise moment due to frictional force and curves, and the pressure contact force of the annular protrusion 18 portion tends to decrease, but since the annular side end surface 16 immediately comes into contact with the groove side wall 2a, The end surface 16 functions as a stopper, the lip portion 13 no longer curves and rotates clockwise, and the pressure of the annular protrusion 18 against the cylinder inner surface 3 hardly decreases.

In short, when the piston 4 moves to the left as shown in Fig. 4a, the sealing performance at the annular protrusion 18 portion tends to loosen, but the end face 16 abuts against the groove side wall 2a, which can reduce the sealing performance. This has the advantage of being able to prevent

Moreover, this effect is similarly exerted on the left lip portion 13 (FIG. 4), so that a dual-effect seal is obtained that exhibits an equal sealing function on the left and right sides.

The shape of the annular groove 2 can also be a simple rectangular cross section, and the processing cost of the groove can be reduced.

(8) When the seal is attached, the cylindrical part 15 is made to have a diameter that is approximately the same as the groove shoulder part 14, so even when the end face 16 abuts against the groove side wall 2a, the seal material on the outer peripheral edge of the end face 16 is in the groove. There is no risk of overhanging the shoulder portion 14, the shape of the cylindrical portion 15 is maintained, and the function of preventing the annular protrusion 1B from getting caught in the gap 19 is advantageously maintained for a long period of time.

The inventor of this application used a pneumatic cylinder and set the experimental conditions (
1) Cylinder size: Nominal 80〆, (2) Air pressure: 5
kg/crrL2, (3) Sliding speed: 0.14 m/
Bee, (4) R of circular annular projection: 0.3 mm,
(5) Number of listening stickers: 2, (6) Pressure medium: dry air.The results showed that (1) the sliding resistance was approximately 0.1 kg, which was extremely small (U packing (approximately 1 to 1.5 kg if three are used); (2) Even if the mileage reaches 600b, there is almost no wear on the sealing surface, so it is thought that it can be used even at 2 to 3 times the mileage. (If you use 3 U packskins, the average is 100~
(200IaIL and 400b at the highest) and has an extremely long life (3) Furthermore, no stick-slip phenomenon was observed during this period.

As described above, the superiority of the oil-free seal of the present invention has been demonstrated.

The oil-free seal of the present invention can be used not only for gases but also for liquids.

[Brief explanation of the drawing]

Figures 1 to 3 are vertical cross-sectional partial views showing a conventional seal structure, Figures 4 to 6 are drawings showing the cross-sectional shape of the oil-free seal according to the present invention in a free state, and Figure 4a is a partial longitudinal cross-sectional view showing a conventional seal structure. FIG. 5 is a partial cross-sectional view showing the installed state of the oil-free seal of FIG. 4; 2... Annular groove, 2a... Side wall, 3... Cylinder inner surface, 4... Piston, 12... Seal body, 13...
... Lip portion, 15... Cylindrical portion, 16... Annular side end surface, 17... Grease reservoir, 18... Arc-shaped annular projection, 19... Gap.

Claims (1)

[Scope of utility model registration request] It has at least a pair of annular lip parts that open from the center of the seal body toward the sliding surface and has a V-shaped cross section, forms a grease reservoir between the lip parts and the sliding surface, and is installed in an annular groove with a rectangular cross section. In the annular unfed seal for reciprocating motion, the seal body is provided with a stable seal bottom that elastically presses against both side walls of the groove bottom when installed, and the tip of each lip comes into contact with the sliding surface to achieve a sealing effect. An annular projection with a small arc-shaped cross section is provided on the side wall of the seal mounting groove of the lip portion, and the annular projection comes into contact with the groove side wall during reciprocating movement, thereby causing the annular projection to contact the shoulder of the ridge groove. A part of the stopper that prevents it from being caught in the gap between the sliding surface and the sliding surface is provided adjacent to the annular protrusion so as to separate a small gap from the groove side wall when the stopper is stopped, and a part of the stopper is attached with a seal. A supply oil seal device characterized in that it is formed of an annular end face parallel to the side wall of the ridge and a cylindrical portion having a diameter approximately equal to the shoulder of the ridge.