JPH10184930A - Rotary shaft seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exercise sufficient sealing performance in any rotational directions by providing a helical groove of both right and left winding directions in the contact surface side of a seal lip part with a rotary shaft in a rotary shaft seal provided with a seal element having a seal lip part surface contacted with the outer peripheral surface of the rotary shaft. SOLUTION: A rotary shaft seal 1 fitted between a housing 2 and a rotary shaft 3 and slide-contacted with the outer peripheral surface 3a of the rotary shaft 3 includes a first seal element 4 held by a first holding metal fitting 6 and a second seal element 5 held between a second holding metal fitting 7 and the first seal element 4. Helical grooves 52 and 53 are formed in the rotary shaft contact surface 51a of a seal lip part 51 surface-contacted by a specified width with the outer peripheral surface of the rotary shaft 3 formed in the second seal element 5 in both right and left winding directions. Thus, even if the rotary shaft 3 is rotated in any directions, a pumping action occurs in a returning/sending direction and sufficient sealing performance is provided for the rotations of both left and right directions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating shaft seal, and more particularly, to a rotating shaft rotating direction in which the rotating direction of the rotating shaft is bidirectional or unidirectional, but the rotating direction is unknown at the time of manufacturing the rotating shaft seal. The present invention relates to a rotary shaft seal suitable for a case where there is no direction.

[0002]

2. Description of the Related Art Conventionally, as a rotary shaft seal provided between a housing and a rotary shaft, there is a rotary shaft seal provided with a seal element having a seal lip portion in surface contact with the outer peripheral surface of the rotary shaft. In compressors and the like, the rotary shaft seal is used to prevent fluid leakage from the rotary shaft, and as a seal element of the rotary shaft seal, it has excellent wear resistance, heat resistance, chemical resistance, and the like. For example, a seal element made of a synthetic resin is used. However, since the sealing element made of a synthetic resin has high rigidity, if the contact surface of the sealing lip portion with the rotating shaft is smooth, sufficient sealing performance cannot be obtained.

Accordingly, a rotary shaft seal has been developed in which a groove is provided on a contact surface of the seal lip portion with the rotary shaft. For example, sealing is performed by using a pumping action in which a rotating flow is generated along a spiral groove when the rotating shaft is rotated. That is, when the rotation direction of the rotation shaft is one direction,
As shown in FIG. 4, a spiral groove 52 is formed on the contact surface of the seal element 5 with the rotating shaft in a direction in which the pumping action is generated toward the fluid storage chamber. Thereby, when the rotating shaft rotates, the fluid is pushed back to the fluid storage chamber side, so that the sealing performance is improved.

However, when the rotating shaft rotates in both directions, a seal lip portion provided with a spiral groove as described above is manufactured. When the rotating shaft is rotated to one direction, the pumping action causes the fluid to flow. Working in the direction of pushing back to the storage chamber side, it can be effectively sealed, but when the rotating shaft is rotated to the other side, the pumping action works on the opposite side to the above-mentioned working direction, so the fluid will be pushed out to the low pressure side, It will promote fluid leakage.

Therefore, when the rotating shaft rotates in both directions, the rotating shaft seal shown in FIG. 5 is used. That is, a structure in which a plurality of concentric annular grooves 54 are provided on the contact surface of the seal element 5 with the rotating shaft has been developed. However, in the case of the concentric annular groove 54, since the pumping action as described above does not occur, the sealing performance is reduced as compared with the case where the spiral groove 52 is provided, and it is difficult to obtain a sufficient sealing performance.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a rotary shaft seal which can obtain a sufficient sealing performance in any rotational direction without depending on the rotational direction of the rotary shaft. .

[0007]

According to the present invention, there is provided a rotary shaft seal provided with a seal element provided between a rotary shaft and a housing and having a seal lip portion in surface contact with the outer peripheral surface of the rotary shaft. A shaft seal, wherein a right-handed and left-handed spiral groove is provided on the contact surface side of the seal lip portion with the rotating shaft.

The seal lip portion is not particularly limited as long as spiral grooves in both right-handed and left-handed directions are provided on the contact surface side with the rotating shaft, and the right-handed groove and the left-handed groove form a spiral groove. The shape and number may be different, but in general, in the case of a two-way rotating shaft seal, the same sealing performance is required for both rotations, and the direction of rotation is unknown when manufacturing the rotating shaft seal. In such a case, it is required that the spiral grooves in both directions have the same sealing performance. It is preferable because it disappears.

Further, when spiral grooves are provided in both the right-handed and left-handed directions, the pumping action is performed in a direction of returning to the fluid storage chamber side (hereinafter referred to as a returning direction) and a direction of sending to the low pressure side (feeding direction). It acts on both, but the action in the return direction works more strongly, and a sealing effect can be obtained. However, by providing the contact surface pressure of the seal lip portion on the outer peripheral surface of the rotating shaft such that the contact surface pressure is higher on the low pressure side than on the fluid storage chamber side, the action in the return direction is more likely to work, and further effective sealing performance Is preferred because

Means for increasing the contact surface pressure of the seal lip portion on the outer peripheral surface of the rotary shaft on the low pressure side from the fluid storage chamber side include a curved portion of the seal element caused by the surface contact of the seal lip portion of the seal element. Can be used to reduce the radius of curvature, or to reduce the width between the spiral grooves from the fluid storage chamber side toward the low pressure side.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail. FIG. 1 is a view showing one embodiment of a rotary shaft seal of the present invention. Referring to the drawings, the rotating shaft seal 1 is fitted between a housing 2 such as a case and the rotating shaft 3 and slidably contacts an outer peripheral surface 3a of the rotating shaft 3 to remove the fluid in the fluid storage chamber R. Seal.

The rotary shaft seal 1 is attached to a first holding member 6, a first seal element 4 made of a rubber elastic body held by the first holding member 6, and a low pressure side L of the first holding member 6. And a second seal element 5 made of a synthetic resin held between the second hold metal 7 and the first seal element 4.

The seal lip 41 of the first seal element 4 has a substantially rectangular cross section, and its tip is inclined at a predetermined angle in the inner diameter direction and the fluid storage chamber R direction. In addition, a sharp inner peripheral ridge 41a is formed to protrude in the inner diameter direction and contact the outer peripheral surface of the rotating shaft in a substantially line contact state.

Before the rotary shaft is inserted, the second seal element 5 has an annular flat plate shape, and its inner peripheral edge is a free edge and lies on a plane orthogonal to the axis.
Then, as shown in FIG. 1, when inserted into the rotating shaft, the inner peripheral side of the second seal element 5 is curved toward the fluid storage chamber R side, fitted, and brought into surface contact with the outer peripheral surface of the rotating shaft with a predetermined width. Thus, the seal lip 51 is formed. As shown in FIG. 2, a flat second seal element 5 in a free state is provided on the rotating shaft contact surface 51 a of the seal lip portion 51.
Spiral grooves 52 and 53 are formed in both the right-handed direction and the left-handed direction.

The rotating shaft seal 1 thus configured is
When the rotating shaft 3 is stationary, the fluid is sealed by the seal lip portion 41 of the first seal element 4, and when the rotating shaft 3 is rotating, the fluid is sealed by the seal lip of the second seal element 5. Sealed by the part 51.

When the rotary shaft 3 is rotating, the seal has spiral grooves 52, 53 formed in both right-handed and left-handed directions as shown in FIG. Also when rotating in the direction, the pumping action occurs in both the return direction and the feed direction, and the pumping action in the return direction works more strongly. Therefore, sufficient sealing performance can be obtained for rotation of the rotating shaft 3 in both directions.

In such a rotary shaft seal, the spiral groove formed in the seal lip portion is not particularly limited as long as the spiral groove in both right and left directions is provided on the contact surface side with the rotary shaft. , Pitch and number of spiral grooves, number of windings,
The depth and the like can be determined as appropriate, and the right-handed spiral groove and the left-handed spiral groove may be formed differently.

However, from the viewpoint of effectively generating the pumping action, the number of turns is preferably three or more, and the number of grooves may be a plurality of right-handed and left-handed. If each of the grooves is formed one by one, processing becomes easy.

In the case of a right-handed spiral groove and a left-handed spiral groove, if the required sealing performance is different depending on the rotation direction of the rotating shaft, it is better to make the shape of the spiral groove different. The same sealing performance is required for both rotations, and if the rotation direction is unknown at the time of manufacturing the rotating shaft seal, it is required to have the same sealing performance for rotation in both directions, It is preferable that the spiral grooves have the same shape except for the winding direction, because there is no restriction on the rotating direction of the rotating shaft.

In the case where the rotary shaft seal has two or more seal elements that are in surface contact with the outer peripheral surface of the rotary shaft, for example, a right-handed winding is performed on at least one of the plurality of seal elements that are in surface contact. It is sufficient that spiral grooves in both directions, left and right, are formed, and can be appropriately determined according to the sealing performance required for the rotary shaft seal.

[0021]

Embodiment 1 A specific embodiment will be described below. In this embodiment, a rotary shaft seal having the structure shown in FIGS. FIG. 1 is a sectional view showing a rotary shaft seal according to the present embodiment, and FIG. 2 is a plan view showing a state before the inner peripheral edge of the seal element is curved. More specifically, according to the drawings, the rotating shaft seal 1 is fitted between a hole 2 of a housing such as a compressor case and the rotating shaft 3 and slidably contacts an outer peripheral surface 3 a of the rotating shaft 3. The fluid in the storage chamber R is sealed.

The rotary shaft seal 1 is attached to a first holding member 6, a first sealing element 4 made of a rubber elastic body held by the first holding member 6, and a low pressure side L of the first holding member 6. And a second seal element 5 made of a synthetic resin held between the second hold metal 7 and the first seal element 4.

The first seal element 4 has a seal lip portion 41 that slides substantially in line contact with the outer peripheral surface 3a of the rotating shaft 3;
Outer peripheral contact piece 42 abutting on inner peripheral surface 2a of housing 2
And a connecting piece 43 for connecting the outer peripheral contact piece 42 to the seal lip 41. The inner flange 61 of the first holding member 6 on the fluid storage chamber R side is embedded in the connecting piece 43. Is done.

The seal lip 41 has a substantially U-shaped cross section.
A sharp inner circumferential ridge 41a is formed at the front end portion, which is inclined at a predetermined angle in the direction, and protrudes in the inner diameter direction and comes into substantially linear contact with the outer peripheral surface of the rotating shaft.

The outer peripheral contact piece 42 extends along the outer peripheral surface of the first holding member 6, and the inner peripheral surface is fixed to the outer peripheral surface of the first holding member 6. Are provided on the outer peripheral surface of the outer peripheral contact piece 42. The outer peripheral surface of the outer peripheral contact piece 42 is
Close to a.

Before the rotary shaft 3 is inserted, the second seal element 5 is in the shape of an annular flat plate, and its inner peripheral edge is a free edge and lies on a plane perpendicular to the axis. Then, as shown in FIG.
The inner peripheral edge side of the seal element 5 is curved toward the fluid storage chamber R side, fitted, and brought into contact with the outer peripheral surface 3a of the rotating shaft 3 with a predetermined width to form the seal lip portion 51.

The second seal element 5 is securely held and held between the connecting piece 43 of the first seal element 4 and the inner flange 71 of the second holding member 7, and the seal lip 51
Comes into surface contact with the outer peripheral surface 3 a of the rotating shaft 3. As shown in FIG. 2, spiral grooves 52, 53 centering on the axis of the flat plate-like seal element 5 in the free state are formed on the rotating shaft contact surface 51 a of the seal lip 51 in the right-handed direction and the left-handed direction. Are formed in both directions.

In FIG. 1, reference numeral 8 denotes a retaining ring fixed to the inner surface 2a of the housing 2, which prevents the rotary shaft seal 1 from coming off.

In such a rotary shaft seal, with regard to the pumping ability which greatly affects the sealing performance, the rotary shaft seal of FIG. Using a device shown in FIG. 3 configured to store oil in the low-pressure side L of FIG. 1 using a seal, a test was performed under the measurement conditions shown in Table 1, and the amount of oil leakage was measured. A so-called pumping ability test was performed using the leakage amount as the oil feeding ability (pumping ability) of the rotary shaft seal.

[0030]

[Table 1]

As a sample, the groove shape formed in the seal lip portion 51 which is in surface contact with the outer peripheral surface 3a of the rotating shaft 3 is as follows.
Three rotary shaft seals of the present invention (FIG. 2) formed with right-handed and left-handed bidirectional spiral grooves 52 and 53, and a conventional rotary shaft seal formed with a plurality of concentric annular grooves 54 for comparison (FIG. 2). Table 2 shows the results of the above-mentioned tests performed using two of the above 5).

[0032]

[Table 2]

From the results shown in Table 2, the rotary shaft seal having the seal lip portion 51 formed with the bidirectional spiral grooves 52 and 53 of the present invention is obtained regardless of whether the rotary shaft rotates clockwise or counterclockwise. It can be seen that pumping ability is higher than that of the rotating shaft seal having the seal lip portion 51 in which the concentric plural annular grooves 54 are formed. Therefore, since the pumping ability greatly affects the sealing performance,
The rotating shaft seal of the present invention is compared with the conventional rotating shaft seal,
It can be seen that the sealing performance is improved in any rotation direction of the rotating shaft.

[0034]

According to the rotating shaft seal of the present invention as described above, a sealing effect can be obtained without depending on the rotating direction of the rotating shaft. This has an excellent effect that the sealing performance can be improved and a rotating shaft seal that can cope with both rotations in both directions can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a rotary shaft seal of the present invention.

FIG. 2 is a plan view showing a state before the inner peripheral edge of a seal element in which a groove is spirally formed in both directions is curved.

FIG. 3 is a sectional view showing a pumping ability test device for a rotary shaft seal.

FIG. 4 is a plan view showing a state before the inner peripheral edge of the seal element is curved when a conventional groove is formed in a spiral shape in one direction.

FIG. 5 is a plan view showing a state before the inner peripheral edge of another seal element is curved when a conventional groove is formed concentrically.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rotary shaft seal 2 housing 3 rotary shaft 4 first seal element 5 second seal element 51 seal lip portion 52, 53 spiral groove 54 multiple concentric annular grooves 6 first holding fitting 7 second holding fitting 8 retaining ring

Claims (2)

[Claims] 1. A rotary shaft seal provided with a seal element provided between a rotary shaft and a housing and having a seal lip portion in surface contact with an outer peripheral surface of the rotary shaft, wherein rotation of the seal lip portion is performed. A rotary shaft seal, wherein a right-handed and left-handed spiral groove is provided on a contact surface side with a shaft. 2. A spiral groove in both right-handed and left-handed directions,
2. The rotary shaft seal according to claim 1, wherein the spiral grooves have the same shape except in the winding direction.