JPH0747607Y2 - Reciprocating actuator seal structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a reciprocating actuator seal structure capable of preventing the oil from leaking out and preventing the dust seal from coming off.

(Prior Art) In the conventional reciprocating actuator shown in FIG. 7, a piston (not shown) in which a piston rod 2 is provided in a cylinder tube 1 is slidably installed.

In addition, in the seal structure, a cap member 3 fitted to one end of the cylinder tube 1 is provided with a wiper seal 4, a U ring 5 as a seal member, and a bearing member 6 in this order from the outside in the axial direction.

The wiper seal 4 and the U ring 5 are brought into contact with the piston rod 2, and the bearing member 6 slidably supports the piston rod 2.

On the inner circumference of the wiper seal 4, a dust lip portion 4a is integrally formed on the outer side in the axial direction, and an oil lip portion 4b is integrally formed on the inner side in the axial direction. Further, a metal ring 4c is provided on the outer circumference and is integrally joined to the wiper seal 4.

The wiper seal 4 as described above is the cap member 3
It is press-fitted into an annular seal groove 7 formed on the outer end of the piston via a metal ring 4c, and the tips of the dust lip and oil lip both lip portions 4a, 4b are brought into contact with the piston rod 2.

An oil reservoir 8 is defined between the piston rod 2 and the lip portions 4a, 4b, and a space 9 is defined between the inside of the wiper seal 4 and the outside of the U ring 5. There is. Further, a drill hole 4d is formed at the base of the oil lip portion 4b, and the oil reservoir chamber 8 and the cavity 9 are communicated with each other through the drill hole 4d.

Then, when the piston rod 2 moves upward in the drawing, the piston rod 2 passing through the contact surface of the U ring 5 and having a slight oil film passes through the contact surface of the oil lip portion 4b of the wiper seal 4. The oil film of the piston rod 2 passing through the contact surface of the oil lip portion 4b is scraped off by the tip of the oil lip portion 4b.

In this way, when the piston rod 2 repeats the reciprocating motion, the oil scraped off by the oil lip portion 4b is stored in the void portion 9, and as soon as the oil starts to accumulate in the void portion 9, the drill hole 4d is immediately removed. It flows out to the oil reservoir chamber 8 via. Then, the oil that has flowed out to the oil reservoir 8 leaks to the outside of the wiper seal 4 as the piston rod 2 reciprocates.

Further, the oil that begins to accumulate in the void 9 is immediately discharged to the oil reservoir chamber 8 because the pressure is accumulated due to the filling of the void 9 with the oil, and the action of this pressure causes the wiper seal 4 to move.
This is to prevent the escape.

(Problems to be solved by the present invention) In the conventional reciprocating actuator seal structure as described above, the wiper seal 4 is provided with a drill hole 4d in the oil lip portion 4b, and a gap is provided through the drill hole 4d. The section 9 and the oil reservoir 8 were always in communication.

As described above, since the void 9 and the oil reservoir chamber 8 are always communicated with each other, when oil starts to accumulate in the void 9, even a small amount of oil will immediately leak to the outside of the wiper seal 4. There was a problem of being lost.

There is also a problem that once the oil starts to leak to the outside, it continuously leaks.

The purpose of this invention is that even if oil starts to accumulate in the gap, it does not immediately leak to the outside, it takes time to leak, and the wiper seal does not come out due to the pressure inside the gap. A seal structure for a dynamic actuator is provided.

(Means for Solving the Problem) In order to achieve the above object, the present invention provides a seal mounting portion at the outer end of a cap member slidably inserted with a piston rod, and a dust lip in order from the outside in the axial direction. Part and an oil lip part are fitted to the mounting part, and a main seal is mounted on the inner side in the axial direction of the wiper seal, and between the dust lip part and the oil lip part of the wiper seal. While defining the oil reservoir, in a seal structure in which a gap is defined between axially opposing portions of the wiper seal and the main seal, when a predetermined pressure is applied to the oil lip of the wiper seal in the gap. It is configured with a blind part that opens.

(Operation of the Invention) With the above-described configuration, it is possible to store oil in the void and store the oil in the void until a predetermined pressure is reached.

Further, once the blind portion opens and the oil in the void leaks, the pressure in the void decreases, and the oil is prevented from leaking again until the oil is accumulated again in the void and a predetermined pressure is collected.

(Effect of the present invention) According to the seal structure of the reciprocating actuator of the present invention, the oil can be stored in the cavity and stored in the cavity until a predetermined pressure is retained. You can delay the time when it leaks.

Therefore, even if the oil starts to collect in the gap, the oil does not immediately leak to the outside, and the time until it leaks can be extended as compared with the conventional case.

Also, once the blind part opens and the oil in the gap leaks to the outside, the pressure in the gap decreases and the oil is prevented from leaking out until the oil accumulates in the gap again and a predetermined pressure is collected. To do.

Therefore, even if the oil leaks to the outside, it does not continuously leak.

Furthermore, since the gap does not exceed a predetermined pressure and is not covered with pressure, the wiper seal does not come out.

(Embodiment of the present invention) In the first embodiment of the present invention shown in FIGS. 1-3, a drill hole 10 is formed at the base of the oil lip portion 4b of the wiper seal 4, and one end of the drill hole 10 is formed. A blind portion 11 for closing this is provided, and other configurations are the same as those of the conventional one.

The drill hole 10 shown in FIGS. 1 and 2 has its opening facing the void portion 9, and the opposite side to the opening is
The blind portion 11 is opposed to the oil sump chamber 8, and the blind portion 11 blocks communication between the void 9 and the oil sump chamber 8.

Then, the piston rod 2 repeatedly reciprocates,
When the oil scraped off by the oil lip portion 4b of the wiper seal 4 fills the void portion 9, the void portion 9 is in a state in which pressure is successively applied.

In such a state, a force for pushing the wiper seal 4 outward acts, but at this time, the gap 9 is formed so that the wiper seal 4 is not pushed outward.
When a predetermined pressure is applied to the blind portion 11, the blind portion 11 is broken by the action of this pressure.

Now, when the pressure is successively applied to the void portion 9 and the inside pressure of the void portion 9 reaches the above-mentioned predetermined pressure, the blind portion 11 is broken, and a gap 11a is formed in the blind portion 11 as shown in FIG. It And
The void portion 9 communicates with the oil reservoir chamber 8 through the gap 11a.

As described above, when the void portion 9 communicates with the oil reservoir chamber 8, the oil accumulated in the void portion 9 leaks to the outside via the gap 11a → the oil reservoir chamber 8. In addition, once the oil leaks, the pressure in the void 9 decreases, and the opening is closed by the elastic force of the blind portion 11 which is an elastic material. Then, the communication between the gap 9 and the oil reservoir 8 is blocked, and the oil is prevented from leaking out until the oil is accumulated again in the gap 9 and a predetermined pressure is accumulated.

With the above configuration, according to the first embodiment,
The oil scraped off by the oil lip portion 4b of the wiper seal 4 is stored in the space 9 and can be stored until the space 9 has a predetermined pressure.

As mentioned above, oil can be stored in the void,
This time can delay the time when the oil leaks to the outside.

Therefore, even if the oil starts to collect in the gap, the oil does not immediately leak to the outside, and the time until it leaks can be extended as compared with the conventional case.

Also, once the blind portion breaks open and the oil in the void leaks to the outside, the pressure in the void drops, and the oil leaks are prevented from leaking again until the oil accumulates in the void 9 and a predetermined pressure is collected. To be done.

Therefore, even if the oil starts to leak to the outside, it does not continuously leak.

Furthermore, since the pressure does not exceed the predetermined pressure and remains in the gap, the wiper seal does not come out.

The second embodiment shown in FIGS. 4 to 6 corresponds to the first embodiment shown in FIG.
The blind portion 11 of the drill hole 10 provided in the embodiment is constituted by the blind portion 12 shown in FIGS.

The blind portion 12 shown in FIGS. 4 and 5 has slits a, b and c which are continuous in a U shape cut into one side of the oil lip portion 4b. The lip portion 4a is penetrated from the void portion 9 side to the oil reservoir chamber 8 side.

Further, one side connecting the inner ends of the slits b and c is defined as a non-cutting portion 13. The non-cutting portion 13 normally holds the blind portion 12 in the illustrated state.

Then, the piston rod 2 repeatedly reciprocates,
When the void 9 is filled with oil and the inside of the void 9 reaches a predetermined pressure, the blind portion 12 is pressed by the action of this pressure. The blind portion 12 bends with the non-cutting portion 13 as a fixed end, and the end of the blind portion 12 near the slit a bends toward the oil reservoir 8 side.

As described above, when the tip end of the blind portion 12 is bent toward the oil reservoir 8 side, the tip end of the blind portion 12 is opened and a gap 12a is formed between the opposed portions, as shown in FIG.

Then, the oil accumulated in the void 9 flows out to the oil reservoir chamber 8 through the gap 12a, and the pressure in the void 9 decreases, so that the blind portion 12 which is an elastic member is restored by its elasticity. Return to the state of.

After all, according to the second embodiment as well, the oil does not immediately leak to the outside, and the time until it leaks can be extended as compared with the conventional case.

Moreover, even if oil starts to leak, it does not continuously leak.

Furthermore, since the pressure does not exceed the predetermined pressure and remains in the gap, the wiper seal does not come out.

[Brief description of drawings]

FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 is a sectional view of an essential part, FIG. 2 is a front view of an essential part taken along the line II-II of FIG. 1, and FIG. Is a sectional view of a main part showing a state in which a blind part is opened, FIGS. 4 to 6 show a second embodiment, FIG. 4 is a perspective view of the main part, and FIG. 5 is a VV cross section of FIG. FIG. 6 is a perspective view of a main part showing a state in which the blind part of FIG. 5 is opened, and FIG. 7 is a sectional view showing a conventional example. 2 ... Piston rod, 3 ... Cap member, 4 ... Wiper seal, 4a ... Dustrip part, 4b ... Oil lip part, 7 ... Seal groove, 8 ... Oil reservoir, 9 ... Void part , 11, 12 …… Blind part.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A seal mounting portion is provided on an outer end of a cap member slidably inserted through a piston rod, and a wiper seal having a dust lip portion and an oil lip portion is sequentially fitted from the outer side in the axial direction. While wearing the main seal on the inner side of the wiper seal in the axial direction, partitioning the oil reservoir between the dust lip part and the oil lip part of the wiper seal, the axial direction of the wiper seal and the main seal A seal structure for a reciprocating actuator, comprising a seal structure in which a gap is defined between opposed parts, and a blind portion that opens when a predetermined pressure is applied to the oil lip of the wiper seal is provided.