JP4032730B2 - Sealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used in, for example, transmissions of various internal combustion engines, industrial robots, and the like, and is provided in a gap between an outer peripheral surface of a shaft member penetrating the housing and the inner peripheral surface of the housing, and the housing is interposed through the gap. The present invention relates to a sealing device that prevents a sealing liquid inside from flowing out.
[0002]
[Prior art]
In various internal combustion engine transmissions, power steering devices, and the like, there is a portion where a shaft member penetrating the housing is provided to rotate relative to the housing. In general, an oil seal (sealing device) is provided at such a portion in order to prevent the hydraulic oil in the housing from flowing out through a gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the housing. Provided.
[0003]
FIG. 4 is a cross-sectional configuration diagram illustrating an example of a conventionally known sealing device of this type.
[0004]
As shown in the figure, the sealing device 101 is provided around the inner peripheral surface 102 a of the housing 102 or the outer peripheral surface 103 a of the rotating shaft 103 in the gap between the housing 102 and the shaft member (rotating shaft) 103. It has a ring shape. The sealing device 101 includes a main lip 111 that is in sliding contact with the outer peripheral surface of the rotary shaft 103 in the sealed liquid side space (inner space) S1 of the housing 102 filled with the liquid to be sealed (hydraulic oil), and the outer space S2 side of the housing 102. And a dust strip 116 that is in sliding contact with the outer peripheral surface of the rotating shaft 103. The main lip 104 mainly has a function of preventing hydraulic oil from leaking from the internal space S1 to the external space S2. The dust lip 116 mainly has a function of preventing entry of dust and the like from the external space S2 into the internal space S1. The annular metal spring 115 biases the main lip 111 toward the outer peripheral surface of the rotating shaft 103. The metal reinforcing ring 114 embedded in the main body of the sealing device 101 has a function of stably holding the shape of the sealing device 101. Further, the pump groove 135 carved on the surface of the main lip 111 has a function of pushing back the hydraulic oil leaked from the internal space S1 to the external space S2 to the internal space S1 side (pump action) when the rotary shaft 103b rotates. Have
[0005]
[Problems to be solved by the invention]
By the way, in the sealing device 101 as described above, for example, when employed in a system in which the rotation operation of the shaft member (or housing) is switched at high speed in the forward and reverse directions as shown in FIG. However, there is a concern that a sufficient pumping action cannot be exhibited, and that the shape of the sealing device 101 itself cannot be stably maintained because the shaft member and the housing perform such a transient operation. It was.
[0006]
Also, when used in an environment where there is a large amount of wear powder generated from mechanical elements (for example, gears) inside the housing, a large amount of wear powder bites into the sliding contact portion between the main lip and the rotating shaft, There was also a concern that the sealing performance would be reduced.
[0007]
The present invention has been made in view of such circumstances, and the object of the present invention is to be provided in the gap between the outer peripheral surface of the shaft member penetrating the housing or the like and the inner peripheral surface of the housing. It is an object of the present invention to provide a sealing device that can reliably prevent the sealing liquid in the housing from flowing out to the outside through a gap over a long period of time.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is fixed to one member of a housing and a shaft that are coaxially provided and rotate relative to each other, and a predetermined liquid to be sealed is accommodated in an annular gap between the housing and the shaft. has been an inner space side, a sealing device for sealing along an external space side in the axial direction of the shaft, the housing and shaft, while changing the rotational direction of the relative forward and reverse, speed positive On the other hand, in a sealing device that is used under a usage environment in which each rotating operation up to 3000 rpm is repeated, a first sealing member having a main lip that is in sliding contact with the other member of the housing and the shaft And a screw part for pushing the liquid to be sealed back to the inner space side in both the forward and reverse rotation directions, the first seal member, and the inside of the main lip And a second sealing member provided with a sub lip of said between side against the other member in sliding contact with the flat sealing surface of the annular, wherein the threaded portion of the shaft from the tip of the main lip A plurality of screw protrusions formed to be inclined in different directions along the axial direction, and each angle of the plurality of screw protrusions inclined in the different direction with respect to the axis of the shaft is 20 to 40 degrees; And the interval between the plurality of screw protrusions is 0.5 to 0.9 mm, and the apex angle of the plurality of screw protrusions is 110 to 130 °.
[0009]
According to this configuration, even when the housing and the shaft rotate relatively in either forward or reverse directions, the liquid to be sealed leaked to the sliding surface of the main lip is efficiently pushed back into the internal space. Become.
[0010]
Furthermore, since the sub lip effectively prevents foreign matter from getting into the main lip, it is sufficient even in a usage environment where the rotational direction of the relative rotation of the housing and the shaft is changed transiently. Secure sealing function.
[0012]
According to this configuration, by adopting the protrusion shape as the structure of the screw portion, not only the sliding contact area is reduced, but also the screw portion is inclined along the axial direction of the shaft from the tip of the main lip. By having the screw shape formed in the direction, when the rotation direction of the relative rotation of the housing and the shaft is changed to both the forward rotation direction and the reverse rotation direction, the stress concentration on a specific part of the structure is small. Thus, the deformation of the screw protrusion is also reduced. The sealing performance and the durability performance are improved at the same time, and a high sealing performance is ensured over a long period of time.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0014]
FIG. 1 is a schematic sectional view of a sealing device 1 according to an embodiment of the present invention.
[0015]
In the figure, reference numeral 1 denotes the whole sealing device, which is fixed to the housing 2 and seals the annular gap between the rotary shaft 3.
[0016]
The sealing device 1 includes a first seal member 10 that includes a main lip 11 and a second seal member 20 that is disposed in the internal space S <b> 1 rather than the first seal member 10.
[0017]
The first seal member 10 is a so-called spring-loaded outer peripheral rubber-type oil seal, and is an annular member having a substantially U-shaped cross section that opens into the sealed liquid side space S1. The first seal member includes an outer cylinder portion 12 fitted to the inner periphery of the housing 2 and a main lip 11 that is in sliding contact with the rotating shaft 3 on the inner periphery side, and includes a rubber-like elastic body 13 and rubber-like elasticity. The metal ring 14 is embedded in the body 13.
[0018]
The metal ring 14 has an L-shaped cross section composed of a cylindrical portion 14 a and an inward flange portion 14 b extending inward from the atmospheric end of the cylindrical portion 14 a, and the cylindrical portion 14 a is a rubber-like shape of the outer cylindrical portion 12. The base end portion 11a of the main lip 11 is provided at the inner end of the inward flange portion 14b.
[0019]
A spring member 15 is attached to the outer periphery of the lip tip portion 11b of the main lip 11 to increase the tightening force.
[0020]
Further, a dust lip 16 extending to the external space S2 is provided at the base end portion 11a of the main lip 11 to prevent dust from entering from the external space S2. Further, a plurality of screw projections 31 and 32 are provided in parallel on the sliding surface 11c of the outer space S2 of the main lip 11 in order to improve sealing performance. These screw protrusions 31 and 32 are used to push the liquid to be sealed (hydraulic oil) back toward the liquid to be sealed side space (internal space) S1 in both the forward and reverse rotation directions of the rotating shaft 3 with respect to the housing 2. The screw part is configured.
[0021]
The second seal member 20 includes a metal ring 21 and a sub-lip 22 made of a rubber-like elastic body that is integrally provided on the inner diameter of the metal ring 21 and that is slidably sealed to the rotary shaft 3.
[0022]
An annular sealing region 7 is formed between the main lip 11 and the sub lip 22. In some cases, the annular sealing region 7 is filled with grease as desired, and the slidability and sealing performance of each lip may be improved.
[0023]
The metal ring 21 forms a cylindrical portion 21a that is fitted to the inner periphery of the outer cylindrical portion 12 of the first seal member, and a flange portion that extends radially inward from the inner space S1 side edge of the cylindrical portion 21a. 21b. The sub lip 22 is inclined to the sealed liquid side space S1 in order to prevent the sludge in the sealed liquid from biting and maintain the sealing performance of the main lip 11, and suppresses the penetration of the sealed liquid into the annular sealed region. . In the present embodiment, the main lip has a threaded portion, and if a slash or the like bites into the threaded portion, the effect of pushing back the sealing fluid is reduced due to damage to the threaded portion or the like. In particular, in the case of a protruding screw, the contact area with respect to the shaft is small, but the influence on sludge is also large, so a sub lip is necessary. Incidentally, even in the case of a groove-shaped screw, it is conceivable that sludge accumulates in the groove and the screw effect is reduced. In addition, in the fitting part α between the cylindrical portion 21a (outer peripheral surface) and the outer cylindrical portion 12 (inner peripheral surface), a part of the cylindrical portion 21a has a convex shape and a part of the outer cylindrical portion 12 has a concave shape. By forming, both members 21a, 12 are fitted to each other. Therefore, even when an external force is applied to the sub lip 22 in the direction β in which the sub lip 22 is separated from the main lip, the sub lip 22 does not fall out of the main lip due to the function of the fitting structure.
[0024]
FIG. 2 is an enlarged plan view showing the screw protrusions 31 and 32 provided on the sliding surface 11 c of the main lip 11.
[0025]
As shown in FIG. 2, the plurality of screw protrusions 31 and 32 formed on the sliding surface 11c are arranged in parallel with a predetermined interval width (L1, L2). Here, the screw protrusion 31 has a predetermined angle θ1 with respect to the axis γ of the rotation shaft 3 (relative to the axial direction), and the screw protrusion 32 has a predetermined angle θ2 with respect to the axis γ of the rotation shaft 3, and each has a different direction (this In the embodiment, each is inclined in a direction substantially symmetrical with respect to the axis γ.
[0026]
FIG. 3 shows a III-III cross section of the screw projection 31 shown in FIG.
[0027]
As shown in FIG. 3, the screw protrusion 31 (the same applies to the screw protrusion 32) has a substantially isosceles triangular cross-sectional shape.
[0028]
In addition, when the rotating shaft 3 changes the forward and reverse rotational directions transiently with respect to the housing 2 and the rotational operation is repeated, the angles θ1 and θ2 are both 20 to 40 ° (more preferably about 30 °). By setting both the interval widths L1 and L2 to 0.5 to 0.9 mm and the apex angle θ3 of the screw protrusion 31 to 110 ° to 130 ° (more preferably about 120 °), the highest shape stability is achieved. It has been confirmed by the inventor that the property and the sealing property can be secured.
[0029]
As described above, according to the sealing device 1 according to the present embodiment, the housing 2 and the rotating shaft 3 leak to the sliding surface 11c of the main lip 11 regardless of whether the housing 2 and the rotating shaft 3 rotate in the forward or reverse direction. The hydraulic oil (sealing target liquid) is efficiently pushed back (pumped) into the internal space.
[0030]
Further, by adopting a protruding shape (see FIG. 3) as the threaded portion on the sliding surface 11c, the sliding contact area (as the entire main lip 11) is reduced, and the durability is improved. Further, since the screw portion has a screw shape formed in an oblique direction along the axial direction of the rotary shaft 3 from the tip 11b of the main lip 11, the rotation direction of the relative rotation of the housing 2 and the rotary shaft 3 is changed. In this case, the stress concentration on a specific part of the structure is reduced, and the deformation of the screw protrusions 31 and 32 is also reduced. Accordingly, the sealing performance and the durability performance are improved at the same time, and the robustness against various disturbances is improved, so that a high sealing performance is ensured for a long time.
[0031]
Further, even when an external force (for example, a reaction force of the outer tube portion 12 against the metal ring 21) is applied to the sub lip 22 in a direction (β) away from the main lip 11, the fitting structure α works. The second seal member 20 does not fall out of the first seal member 10. Therefore, a sufficient sealing function is ensured even in a usage environment in which the rotation direction of the relative rotation of the housing 2 and the rotating shaft 3 is changed transiently.
[0032]
Note that the sealing device 1 according to the present embodiment is employed in a mechanism in which the rotating shaft 3 performs a rotating operation in the fixed housing 2, but the housing is arranged with respect to the fixed shaft member. Also for a mechanism that performs a rotating operation, an effect equivalent to or equivalent to that of the present embodiment can be achieved by applying a structure substantially similar to that of the sealing device 1.
[0033]
Further, the sealing device 1 according to the present embodiment is fixed to the inner peripheral surface of the housing 2 and is in sliding contact with the outer peripheral surface of the rotary shaft 3, but is fixed to the outer peripheral surface of the rotary shaft 3, Even if a configuration in which the inner surface of the housing 2 is slidably contacted is adopted, an effect equivalent to or equivalent to the present embodiment can be obtained.
[0034]
In addition, as a structure of a screw part, it can replace with the screw protrusions 31 and 32 which consist of protrusion shape, and can also employ | adopt a screw groove. However, in order to ensure higher sealing performance and durability performance with respect to the transient relative rotational operation, the embodiment described above is effective in that the contact area with the outer peripheral surface of the rotating shaft 3 can be effectively reduced. It is more preferable to adopt the protrusion shape (screw protrusions 31 and 32) as shown in FIG.
[0035]
【The invention's effect】
As described above, according to the present invention, the liquid to be sealed leaked to the sliding surface of the main lip is efficiently put into the internal space, even when the housing and the shaft rotate in either the forward or reverse direction. It will be pushed back. Therefore, high sealing performance can be ensured even in a use environment where the rotational direction of such relative rotation is repeatedly changed.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional configuration diagram of a sealing device according to an embodiment of the present invention.
FIG. 2 is an enlarged plan view showing a screw protrusion of the main lip according to the embodiment;
3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a schematic configuration diagram of a conventional sealing device.
FIG. 5 is a time chart showing an example of a movement pattern of a shaft member capable of forward and reverse rotation .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sealing device 2 Housing 3 Rotating shaft 7 Annular sealing area 10 First seal member 11 Main lip 12 Outer cylinder part 14 Metal ring 14a Cylindrical part 14b Inward flange part 16 Dustrip 20 Second seal member 21 Metal ring 21a Cylindrical part 21b Flange 22 Sub lip 31, 32 Screw projection

Claims (1)

It is fixed to one member of a housing and a shaft that are coaxially provided and relatively rotate,
A sealing device that seals the inner space side in which a predetermined liquid to be sealed is accommodated in the annular gap between the housing and the shaft from the outer space side along the axial direction of the shaft,
The housing and the shaft is relatively while changing the forward and reverse rotation direction, the sealing device used in a used environment such as repeated rotation operation speed reaches the maximum in the forward and reverse respectively to 3000 rpm,
A first seal member having a main lip that is in sliding contact with the other member of the housing and shaft;
A screw part for pushing the liquid to be sealed back to the inner space side in both forward and reverse rotation directions;
Is fitted to the first sealing member, and a second sealing member provided with a sub lip for sliding contact with a flat sealing surface of the annular against the other member in the inner space side of the main lip,
Have
The screw portion has a plurality of screw protrusions formed to be inclined in different directions along the axial direction of the shaft from the tip of the main lip,
Respective angles of the plurality of screw projections inclined in different directions with respect to the axis of the shaft are 20 to 40 °,
An interval between the plurality of screw protrusions is 0.5 to 0.9 mm;
The apex angle of the plurality of screw protrusions is 110 to 130 °.

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