JP2012072822A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sliding load from increasing due to a negative pressure generated by screw pumping action of a spiral concave and convex portion 15c, and to prevent muddy water and dust from entering from the side of an atmosphere B.SOLUTION: This sealing device includes a first seal 1 whose outer diameter part 12 is closely fitted and fixed to a housing 3, having a seal lip 15 whose inner diameter edge 15a near the front end facing the side of a machine inside A is brought slidably into close contact with a rotor 4 having an approximately horizontal axis O, and a second seal 2 which is located outside the seal lip 15 and mounted on the first seal 1, having an external lip 22 which is brought slidably into close contact with the rotor 41. On the inner peripheral face of the seal lip 15, the spiral concave and convex portion 15c is formed which generates the screw pumping action toward the side of the machine inside A when the rotor 4 rotates in a fixed direction. On the axially outside and outer-diameter side of a sliding part S of the seal lip 15, a ventilation passage E is formed to allow a space D between the first seal 1 and the second seal 2 to communicate with the side of the atmosphere B.

Description

  INDUSTRIAL APPLICABILITY The present invention is used as a sealing means for rotating parts in automobiles and industrial machines, and particularly in harsh conditions that are exposed to external muddy water and dust, such as undercarriages such as agricultural machinery and civil engineering / construction machinery. The present invention relates to a sealing device suitable for use.

  2. Description of the Related Art Conventionally, some sealing devices that seal the outer periphery of a rotating body having a substantially horizontal axis with a sealing lip include a dust strip for preventing intrusion of muddy water or the like from the atmosphere. FIG. 3 shows a typical prior art of this type of sealing device, and includes an outer diameter portion 101 tightly fitted and fixed to an inner peripheral surface of a substantially horizontal shaft hole of a housing (not shown), and an inner periphery thereof. A seal lip 102 extending from the inside of the machine A to the in-machine A side, and a dust lip 103 positioned on the atmosphere B side of the seal lip 102 and provided on the inner periphery of the outer diameter portion 101 and extending to the atmosphere B side. The oil slidable in close contact with the outer peripheral surface of a substantially horizontal rotator (not shown) inserted through the shaft hole seals the oil in the machine, and the dust lip 103 is connected to the outer periphery of the rotator. By being slidably in close contact with the surface, muddy water and dust are prevented from entering from the atmosphere.

  In this type of sealing device, in order to enhance the sealing function against oil or the like in the machine A, the surrounding fluid is applied to the inclined surface (conical surface) 102b on the atmosphere B side of the inner diameter edge 102a of the seal lip 102 by the rotation of the rotating body. A spiral protrusion or spiral groove 102c that generates a pumping force to be pushed out toward the machine A side is formed. Further, in the case of those used under harsh conditions exposed to muddy water or the like, a plurality of dust strips 103 are provided as shown in the example to prevent muddy water and dust from entering as much as possible.

  However, the pumping by the spiral unevenness (spiral ridge or spiral groove) 102 c formed on the seal lip 102 acts to discharge the air existing in the space C between the seal lip 102 and the dust lip 103 to the in-machine A side. Therefore, the space C becomes a negative pressure under the condition that the pumping force is increased due to an increase in rotational force or the like. In this case, the negative pressure in the space C (due to the pressure difference between the space C and the atmosphere B) causes the dust strip 103 to be attracted to the outer peripheral surface of the rotating body, increasing the sliding load, and increasing heat generation and wear. There was a risk of coming.

  Therefore, in order to prevent the space C from becoming negative pressure due to the screw pump action of the spiral unevenness 102 c formed on the seal lip 102, a plurality of protrusions 103 a are provided on the inner peripheral surface of the dust lip 103, or the following As described in Patent Document 1, it is known to form a gap between the dust lip and the outer peripheral surface of the rotating body by providing a notch on the inner peripheral surface of the dust lip. However, in this case, there is a concern that muddy water and dust from the atmosphere B side may easily enter the in-machine A side through between the dust lip 103 and the outer peripheral surface of the rotating body.

JP 2003-336746 A

  The present invention has been made in view of the above points, and its technical problem is to prevent an increase in sliding load due to the negative pressure due to the screw pump action of the spiral irregularities formed on the seal lip. At the same time, it is to prevent the infiltration of muddy water and dust on the atmosphere side.

  As a means for effectively solving the technical problem described above, the sealing device according to the invention of claim 1 seals the outer periphery of a rotating body whose axis is substantially horizontal, and the outer diameter portion is the rotation. A first seal having a seal lip that is tightly fitted and fixed to a housing on the outer periphery of the body and in which an inner diameter edge near the tip facing the inside of the machine is slidably brought into close contact with the rotating body; and is positioned outside the seal lip. A second seal having an outer lip attached to the outer diameter portion of the first seal and slidably in contact with the rotating body. The rotating body rotates in a certain direction on the inner peripheral surface of the seal lip. As a result, a spiral concavity and convexity that forms a screw pump action is formed toward the inside of the machine, and the space between the first seal and the second seal is opened to the atmosphere on the outer side in the axial direction and outside the sliding portion of the seal lip. Ventilation passage communicating with the side is formed The is intended.

  In the above-described configuration, the first seal seals the fluid to be sealed in the machine by the seal lip being slidably in contact with the rotating body, and the spiral unevenness formed on the inner peripheral surface of the seal lip. The rotary body rotates in a certain direction to produce a screw pump action toward the inside of the machine to enhance the sealing function of the seal lip. The second seal is in close contact with the external lip so that it can slide on the rotary body. By doing so, the first seal is prevented from being directly exposed to atmospheric muddy water and dust. Further, the air passage prevents the space between the first seal and the second seal from becoming negative pressure due to the screw pump action of the spiral irregularities. Since the air passage is provided on the outer side in the axial direction and on the outer diameter side from the sliding portion of the seal lip, muddy water and dust entering from the atmosphere through the air passage to the sliding portion of the seal lip. Is difficult to reach.

  According to a second aspect of the present invention, there is provided the sealing device according to the first aspect, wherein the ventilation path is provided below the axis. If it does in this way, the muddy water and dust which penetrate | invaded from the ventilation path will become difficult to reach the sliding part of the seal lip of the first seal.

  A sealing device according to a third aspect of the present invention is the sealing device according to the first aspect, wherein a number of air passages are provided at appropriate intervals in the circumferential direction, and the air passage and the first seal are provided on the first seal or the second seal. An annular dust receiver is provided so as to project between the seal lip of the seal and the tip having a relatively large diameter. In this way, even if muddy water or dust in the atmosphere enters the air passage and falls above the axis of the substantially horizontal rotating body, the muddy water or dust is captured by the dust receiver and moves in the circumferential direction. It flows down and returns to the atmosphere from the air passage located below the axis of the rotating body. For this reason, the muddy water and dust that have entered from the air passage are more difficult to reach the sliding portion of the seal lip of the first seal.

  According to the sealing device of the first or second aspect of the invention, the space between the seal lip of the first seal and the external lip of the second seal becomes negative pressure by the screw pump action of the spiral irregularities, and the sliding load increases. In addition to preventing muddy water and dust from entering the sliding part of the seal lip, it ensures an excellent sealing function even under harsh conditions exposed to external muddy water and dust. be able to.

It is sectional drawing of the mounting state which cut | disconnects and shows preferable embodiment of the sealing device which concerns on this invention by the plane which passes along the axial center O. FIG. It is the figure which looked at the sealing device of FIG. 1 from the atmosphere B side. FIG. 6 is a half cross-sectional view of a mounting state in which an example of a sealing device according to the prior art is shown cut by a plane passing through an axis O.

  Hereinafter, preferred embodiments of a sealing device according to the present invention will be described with reference to the drawings. First, FIG. 1 is a cross-sectional view of a mounting state in which an embodiment of a sealing device according to the present invention is cut along a plane passing through its axis O.

  The sealing device shown in FIG. 1 is tightly fitted and fixed to a seal mounting portion 32 having an outer diameter portion enlarged in the shaft hole 31 of the non-rotating housing 3, and the inner diameter edge in the vicinity of the tip facing the inner side is the above-mentioned. A first seal 1 having a seal lip that is slidably in contact with a rotating shaft 4 inserted in the inner periphery of the shaft hole 31, and an outer diameter portion of the first seal 1 located outside the seal lip. It consists of a second seal 2 with an external lip attached and slidably in contact with the rotary shaft 4. The rotating shaft 4 corresponds to the rotating body described in claim 1.

  Among these, the first seal 1 is integrally formed with a metal reinforcing ring 11 with a synthetic resin material having rubber or rubber elasticity, and has a substantially cylindrical outer diameter base portion 12 and an in-machine A side. A radial direction portion 13 extending from the end portion toward the inner diameter side, a conical cylindrical portion 14 that gradually decreases in diameter from the inner diameter end of the radial direction portion 13 toward the atmosphere B, and an inner diameter end of the conical cylindrical portion 14. A seal lip 15 and a dust strip 16 on the atmosphere B side thereof are provided.

  Specifically, the reinforcing ring 11 in the first seal 1 is manufactured by stamping press molding of a metal plate or the like, and the outer diameter cylindrical portion 11a and the radial direction extending from the end on the machine A side to the inner diameter side. The portion 11b and a conical cylindrical portion 11c having a gradually decreasing diameter from the inner diameter end of the radial direction portion 11b toward the atmosphere B side.

  The outer diameter base portion 12 in the first seal 1 corresponds to the outer diameter portion described in claim 1, and the portion formed on the outer peripheral side of the outer diameter cylindrical portion 11 a of the reinforcing ring 11 is the housing 3. This is a fixed seal portion 12a that is press-fitted into the inner peripheral surface of the seal mounting portion 32, and in the press-fitted state to the seal mounting portion 32, is appropriately compressed in the radial direction, thereby obtaining a fixing force to the housing 3. The airtightness between the housing 3 and the housing 3 is maintained.

  The seal lip 15 in the first seal 1 is formed in a conical cylindrical shape extending from the inner diameter end of the conical cylindrical portion 14 toward the in-machine A side and having a small diameter at the tip. An inner peripheral edge 15a that is slidably in contact with the outer peripheral surface of the rotating shaft 4 with an appropriate margin is formed on the inner periphery of the seal lip 15 in the vicinity of the tip. A large number of spiral protrusions 15c are formed on the conical inner peripheral surface 15b on the atmosphere B side of the inner diameter edge 15a. The spiral protrusion 15c corresponds to the spiral irregularities described in claim 1.

  Each of the spiral protrusions 15c is inclined toward the inner diameter edge 15a toward the rotation direction of the rotating shaft 4, that is, extends at a predetermined inclination angle with respect to the inner diameter edge 15a, and extends so as to form a part of the spiral. Yes. For this reason, when the rotating shaft 4 rotates in a certain direction, the sealing portion which tries to leak the sliding portion S between the inner diameter edge 15a of the seal lip 15 and the outer peripheral surface of the rotating shaft 4 from the in-machine A side to the atmosphere B side. A screw pump action that pushes the target oils and fats back to the in-machine A side is caused.

  A garter spring 17 is attached to the seal lip 15 on the outer peripheral side of the inner diameter edge 15a. The garter spring 17 is formed by connecting a metal coil spring in an annular shape, and compensates for the tight force of the seal lip 15 against the outer peripheral surface of the rotating shaft 4.

  The dust lip 16 in the first seal 1 is formed in a conical cylinder shape that extends from the inner diameter end of the conical cylindrical portion 14 toward the atmosphere B and has a small diameter at the tip. 4 is close to the outer peripheral surface with a small gap or lightly contacted.

  The second seal 2 is formed integrally with a metal reinforcing ring 21 with rubber or a synthetic resin material having rubber-like elasticity, and includes an external lip 22 and a dust receiver 23, and the inner diameter of the second seal 2 is that of the rotary shaft 4. It is larger than the outer diameter.

  Specifically, the reinforcing ring 21 in the second seal 2 is manufactured by stamping press molding or the like of a metal plate, and extends in the radial direction from the outer diameter cylindrical portion 21a and the end on the atmosphere B side to the inner diameter side. It consists of the part 21b. The outer diameter cylindrical portion 21a of the reinforcing ring 21 is press-fitted into the inner peripheral surface of the inner peripheral side portion 12b of the outer diameter cylindrical portion 11a of the reinforcing ring 11 in the outer diameter base portion 12 of the first seal 1. The second seal 2 is fixedly attached to the outer diameter portion of the first seal 1.

  Of the outer diameter base portion 12 in the first seal 1, a plurality of grooves 12 c extending in the axial direction are formed in the inner peripheral side portion 12 b of the outer diameter cylindrical portion 11 a of the reinforcing ring 11. For this reason, between the outer diameter cylindrical part 21a of the reinforcement ring 21 of the second seal 2 press-fitted into the inner peripheral side part 12b of the outer diameter base part 12, the first seal 1 and the second seal are formed by the groove 12c. An air passage E is formed which communicates the space D between the two in the axial direction outside the sliding portion S of the seal lip 15 of the first seal 1 and the outer diameter side of the seal lip 15 and the dust lip 16 with the atmosphere B side. Has been.

  FIG. 2 is a view seen from the atmosphere B side in FIG. As shown in FIG. 2, the air passages E are formed at equal intervals in the circumferential direction (for example, 45 ° intervals). Among these, the ventilation path indicated by reference sign Et opens in the space D between the first seal 1 and the second seal 2 at the top position (position almost directly above the axis), and is indicated by reference sign Eb. The ventilation path opened to the space D at the bottom position (position almost directly below the axis).

  The outer lip 22 of the second seal 2 has a conical cylindrical shape in which the base portion is vulcanized and bonded to the vicinity of the inner diameter end of the radial portion 21b of the reinforcing ring 21 and gradually increases in diameter toward the atmosphere B side. The tip end portion of the rotary shaft 4 is formed integrally with the rotary shaft 4 or is slidably brought into close contact with a flange 41 that is closely fitted and fixed to the outer peripheral surface of the rotary shaft 4. It has become. The flange 41 corresponds to the rotating body described in claim 1.

  The dust receiver 23 in the second seal 2 is located between the air passage E and the seal lip 15 and the dust lip 16 of the first seal 1, and the root portion thereof is the second of the radial portions 21 b in the reinforcing ring 21. It is formed in a conical cylinder shape that is vulcanized and bonded to the surface facing the one seal 1 side, extends from there to the outer peripheral side of the conical cylinder portion 14 in the first seal 1, and gradually increases in diameter. The tip of the dust receiver 23 protrudes toward the first seal 1 from the tip of the outer diameter cylindrical portion 21a of the reinforcing ring 21.

  In the sealing device configured as described above, the outer diameter base 12 of the first seal 1 is press-fitted into the inner peripheral surface of the seal mounting portion 32 of the housing 3, and the seal lip 15 is the outer peripheral surface of the rotary shaft 4. Is sealed so that oils and fats to be sealed in the machine A do not flow out to the atmosphere B side, and the spiral protrusion formed on the inner peripheral surface of the seal lip 15 is sealed. 15c increases the sealing function of the seal lip 15 by generating a screw pump action toward the in-machine A side when the rotating shaft 4 rotates in a certain direction. Further, the dust lip 16 in the first seal 1 prevents muddy water or dust that has entered the space D between the first seal 1 and the second seal 2 from intervening in the sliding portion S of the seal lip 15 and the rotary shaft 4. It is to prevent.

  The second seal 2 prevents the inflow of muddy water and dust from the atmosphere A to the first seal 1 side by the outer lip 22 being slidably in contact with a flange 41 that rotates integrally with the rotary shaft 4. It is. In particular, muddy water and dust that try to pass through the sliding part of the outer lip 22 and the flange 41 to the inner diameter side are easily passed through because they are shaken off to the outer diameter side by the swinging action (centrifugal force) accompanying the rotation of the flange 41. I can't.

  Here, the pumping by the spiral ridge 15c formed on the seal lip 15 acts to discharge the air existing in the space C between the seal lip 15 and the dust lip 16 to the in-machine A side. As described above, the air in the space D between the first seal 1 and the second seal 2 flows into the space C through the minute gap between the dust strip 16 and the rotating shaft 4. Further, the swing-off action at the sliding portion between the external lip 22 and the flange 41 acts to discharge the air in the space D between the first seal 1 and the second seal 2 to the atmosphere B. However, since the space D communicates with the atmosphere B side through the ventilation path E, the space D does not become negative pressure. Therefore, the sliding load of the seal lip 15 with respect to the outer peripheral surface of the rotating shaft 4, The sliding load of the external lip 22 relative to the flange 41 does not increase due to negative pressure.

  In addition, since the air passage E communicates the space D between the first seal 1 and the second seal 2 with the atmosphere B side, muddy water and dust may enter the space D from the air passage E to some extent. Inevitable. However, since the air passage E is provided outside the sliding portion S of the seal lip 15 of the first seal 1 in the axial direction and on the outer diameter side, muddy water entering from the atmosphere B side through the air passage E is provided. The dust does not easily reach the sliding portion S of the seal lip 15.

  Specifically, for example, muddy water or the like that has flowed in through the air passage E located above the axis O (for example, the air passage Et at the top position) is reinforced in the second seal 2 as indicated by reference numeral W1 in FIG. It falls from the tip of the outer diameter cylindrical portion 21a of the ring 21 and is captured by a conical cylindrical dust receiver 23 existing on the lower side (inner peripheral side), and it travels down the small diameter side of the outer peripheral surface in the circumferential direction. As shown by reference numeral W2 in FIG. 1, the tip of the dust receiver 23 that is obliquely downward and below the axis O is on the inner peripheral side portion 12b of the outer diameter base portion 12 of the first seal 1. It falls and returns to the atmosphere B side through the air passage E (for example, the air passage Eb at the bottom position) formed there.

  Further, if a part of the muddy water or the like that has flowed in through the ventilation path Et located above the axis O is indicated by reference numeral W3 in FIG. 1, the outer peripheral surface of the conical cylindrical portion 14 in the first seal 1 Even if the muddy water flows into the gas, the muddy water is prevented from entering the sliding portion S side of the seal lip 15 by the dust lip 16, travels down the outer circumference in the circumferential direction, and vents below the axis O. It returns to the atmosphere B side through the path E (for example, the ventilation path Eb at the bottom position).

  Further, muddy water or the like that has entered from the air passage E opened below the shaft center O does not flow to the sliding portion S side of the seal lip 15 located above the air passage E, but from the air passage Eb or the like at the bottom position. Returned to the atmosphere B side.

  Therefore, even if muddy water and dust enter the space D from the air passage E, the muddy water and dust do not easily reach the sliding portion S of the seal lip 15 of the first seal 1, so that the wear of the seal lip 15 is effective. It is possible to maintain an excellent sealing function against in-machine oil.

  In the illustrated embodiment, the outer lip 22 of the second seal 2 is formed in a conical cylinder shape having a large diameter at the tip, and is in close contact with the flange 41, but the tip has a small diameter. It is good also as a structure formed so that it may form in a conical cylinder shape and the outer peripheral surface of the rotating shaft 4 is slidably contacted.

1 First seal 12 Outer diameter base (outer diameter part)
12c Groove 15 Seal lip 15c Spiral protrusion (spiral unevenness)
16 Dustrip 2 Second seal 22 External lip 23 Dust receiver 3 Housing 4 Rotating shaft (Rotating body)
41 Flange (Rotating body)
A Airplane B Air C, D Space E Ventilation path S Sliding part

Claims (3)

  The shaft center seals the outer periphery of a rotating body that is substantially horizontal, the outer diameter portion is tightly fitted and fixed to the outer housing of the rotating body, and the inner diameter edge in the vicinity of the tip facing the inside of the machine is attached to the rotating body. A first seal having a seal lip that is slidably in contact, and an external lip that is located outside the seal lip and is attached to the outer diameter portion of the first seal and is slidably in contact with the rotating body A spiral concavo-convex structure is formed on the inner peripheral surface of the seal lip, and a screw pumping action is generated on the inner peripheral surface of the seal lip toward the inside of the machine by rotating in a certain direction. A sealing device, characterized in that a ventilation path is formed on the outer side in the axial direction and on the outer diameter side to communicate the space between the first seal and the second seal with the atmosphere side.   The sealing device according to claim 1, wherein the ventilation path is provided below the axis.   A large number of air passages are provided at appropriate intervals in the circumferential direction, the first seal or the second seal is located between the air passage and the seal lip of the first seal, and the tip has a relatively large diameter. The sealing device according to claim 1, wherein an annular dust receiver is protruded.

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