JP6063326B2 - Oil seal - Google Patents

Description

  The present invention relates to an oil seal. More specifically, the present invention relates to the structure of the seal surface of the oil seal.

  In the conventional general oil seal, the tip of the seal lip is composed of two surfaces, a sealed fluid side (oil side) slope (finished surface) and an unsealed fluid side (atmosphere side) slope (seal surface). A sharp edge (a lip tip with a small angle) is formed between the two slopes. Therefore, in the initial stage of use of the oil seal, the contact width (sliding width) between the seal surface of the seal lip and the shaft that is the sliding counterpart is small (narrow). The angle of the sealed fluid side slope (the slope angle of the slope with respect to the central axis, hereinafter the same) θ1 is conventionally known to be 40 to 50 degrees, and the angle θ2 of the non-sealed fluid side slope is the same. Conventionally, a value of 20 to 30 degrees is known (see FIGS. 5 and 6).

  In such a structure of the lip tip and the seal surface of the oil seal, when foreign matter generated inside the device is caught in the contact surface to the shaft of the main seal lip, the sealed fluid side and the non-sealed fluid side are formed on the contact surface. There is a risk that oil leakage may occur due to the formation of a gap to be connected.

  Therefore, as shown in FIGS. 5 and 6, the seal surface angle θ3 of the lip tip 101a of the main seal lip 101 is set to 5 ° to 15 ° smaller than the inclination angle θ1 of the finished surface, and the axial direction of the main seal lip 101 is set. The contact width is increased. With this configuration, even if foreign matter is caught in the seal surface 101b, the foreign matter is difficult to reach the non-sealed fluid side 102, and a gap is formed to communicate the sealed fluid side 103 and the non-sealed fluid side 102. It is also done to suppress this.

JP-A-7-301339

  However, if the seal surface angle θ3 of the lip tip 101a of the main seal lip 101 is reduced, the contact width is expanded, the contact pressure of the lip tip 101a of the main seal lip 101 is weakened, and the sealing performance in the initial sealing state is reduced. There is a problem that it cannot be obtained. That is, it is difficult to achieve a high level of both the sealing performance when a foreign object is caught by securing the contact width of the lip tip 101a and the sealing performance in the initial sealed state by securing the contact pressure.

  It is an object of the present invention to provide an oil seal that can achieve a high level of both the sealing performance when a foreign object is caught by securing the contact width of the lip tip and the sealing performance in the initial sealed state by securing the contact pressure. Objective.

In order to achieve this object, the oil seal according to claim 1 is characterized in that the seal surface of the main seal lip is arranged in order from the tip of the lip to the non-sealing fluid side, the first inclined surface of the seal surface angle γ, and the seal surface angle. a second slope of alpha, is constituted and a third slope of the sealing surface angle beta, the sealing surface angle alpha, gamma, a relationship between beta is α <γ ≦ β, at least a first slope The second slope is in contact with the shaft.

  In the oil seal according to claim 2, a trough between the first slope and the second slope is not in contact with the shaft.

  Furthermore, the oil seal according to claim 3 has a relationship that the seal surface angle γ is 10 to 25 degrees and the seal surface angle α is (γ−2) degrees ≧ α ≧ (γ−8) degrees.

The oil seal of claim 1 wherein each sealing surface angle of the first to third inclined surface constituting the sealing surface of the main seal lip alpha, gamma, relationships beta are the α <γ ≦ β, at least a Since the first slope and the second slope are brought into contact with the shaft, the configuration of the contact surface with the shaft is two steps of the first slope having the seal surface angle γ and the second slope having the seal surface angle α. It becomes composition. For this reason, the contact width of the seal surface with the shaft is widened. For example, even if a foreign matter is generated inside the device and the foreign matter is caught in the first slope on the sealed side, the clearance that allows the sealed side and the non-sealed side to communicate with each other Is less likely to occur, and the sealing performance against foreign matter can be improved. In addition, the setting of the seal surface angle γ of the first slope hardly affects the increase or decrease in the contact width with respect to the shaft of the seal surface, and the degree of freedom in setting the seal surface angle γ can be improved. Therefore, the seal surface angle γ can be increased to reduce the lip tip angle, and the contact pressure to the shaft of the lip tip can be increased to improve the sealing performance in the initial sealing state. Thus, both the increase in contact pressure and the increase in contact width, which are in a trade-off relationship, can be achieved at a high level.

  In the oil seal according to claim 2, since the trough between the first slope and the second slope is not in contact with the shaft, the contact surface with the shaft of the main seal lip is the first surface. It becomes a double structure of 1 slope and 2nd slope. Therefore, the pressure distribution on the contact surface is configured such that the contact pressure at the non-contact portion (the valley between the first slope and the second slope) is small, and the contact pressure increases as the distance from the non-contact portion increases. For example, as shown in FIG. 4, both at the lip tip (first slope tip) 1 b and at the peak portion (second slope tip) 9 between the second slope 5 and the third slope 6. The contact pressure becomes highest, and the contact pressure becomes 0 in the non-contact portion near the valley portion 8 between the first slope and the second slope. Therefore, when the shaft rotates, the air in the non-contact portion space is exhausted to both sides (sealing side and non-sealing side) of the main seal lip, the non-contact portion space becomes negative pressure, The slope of 2 is pulled to the space side of the non-contact part. Therefore, the contact pressure between the first slope and the second slope is increased, and the sealing performance at the initial stage of sealing can be further improved.

  In addition, since the contact surface of the main seal lip with the shaft is doubled between the first slope and the second slope, the contact width at the tip of the lip (contact width of the first slope) is reduced, and the contact pressure is reduced. The contact pressure at the tip of the lip can be further increased by concentrating. Therefore, the sealing performance in the initial sealing state can be further improved.

  In addition, since the contact surface of the main seal lip with the shaft is doubled between the first and second slopes, even if a foreign object is caught in one of the slopes, the other slope It is in contact with the shaft, and it is difficult for a gap to communicate between both sides (sealed side and non-sealed side) of the main seal lip, and oil leakage can be further prevented.

  Further, since the contact surface of the main seal lip with the shaft is doubled between the first inclined surface and the second inclined surface, even if the foreign object passes through one of the inclined surfaces, the foreign object is removed from the non-contact portion. Can be received and held in space. For this reason, it is possible to prevent foreign matter from entering the other slope, and also from this point, it is possible to prevent the occurrence of a gap that communicates both sides (sealed side and non-sealed side) of the main seal lip, thereby preventing oil leakage. This can be further prevented.

  Further, as in the oil seal according to claim 3, it is preferable that the seal surface angle γ is 10 to 25 degrees and the seal surface angle α is (γ−2) degrees ≧ α ≧ (γ−8) degrees. In this case, it is possible to prevent oil leakage due to foreign matter biting by securing the contact width and to ensure a high level of sealing performance in the initial sealed state by securing the contact pressure.

It is sectional drawing which shows an example of embodiment of the oil seal of this invention. It is a figure for demonstrating the shape of the lip front end and seal surface of the oil seal. FIG. 3 is an enlarged view of a lip tip portion showing a mounting state of the oil seal on the shaft. It is a figure which shows the pressure distribution of the contact part in the state which mounted | wore with the same oil seal. It is sectional drawing of the conventional oil seal. It is a figure for demonstrating the shape of the lip front end and seal surface of the oil seal. It is a figure which shows the result of the test and FEM analysis which were performed in order to investigate the sealing performance of the oil seal of this invention.

  Hereinafter, the configuration of the present invention will be described in detail based on embodiments shown in the drawings.

  1 to 3 show an example of an embodiment of the oil seal of the present invention. The oil seal includes a first inclined surface 4 having a seal surface angle γ in which the seal surface 1a of the main seal lip 1 is disposed in order from the lip tip 1b to the non-sealed fluid side 3, and a second inclined surface having a seal surface angle α. 5 and a third inclined surface 6 having a seal surface angle β, the relationship between the seal surface angles is α <γ ≦ β, and at least the first inclined surface 4 and the second inclined surface 5 are on the shaft 7. I try to contact them.

  The first to third slopes 4 to 6 of this embodiment are shown in detail in FIG. Since the relationship between the seal surface angle γ of the first inclined surface 4 and the seal surface angle α of the second inclined surface 5 is α <γ, the valley portion 8 is between the first inclined surface 4 and the second inclined surface 5. It becomes. In the present embodiment, since the relationship between the seal surface angle α of the second inclined surface 5 and the seal surface angle β of the third inclined surface 6 is γ <β, the second inclined surface 5 and the third inclined surface 6 It becomes mountain part 9 between.

  In the present embodiment, the valley portion 8 between the first inclined surface 4 and the second inclined surface 5 is not in contact with the shaft 7.

  Here, it is preferable that the seal surface angle γ is 10 to 25 degrees and the seal surface angle α is preferably (γ−2) degrees ≧ α ≧ (γ−8) degrees. It is possible to ensure a high level of both the prevention of oil leakage due to foreign matter biting by securing and the sealing performance in the initial sealed state by securing the contact pressure. Further, it is more preferable that the seal surface angle γ is 15 to 25 degrees, and the seal surface angle α is (γ−2) degrees ≧ α ≧ (γ−8) degrees. It is easy to secure the pressure, and the sealing performance in the initial sealed state can be improved. However, the values of the seal surface angles α and γ are not limited to these.

  The ratio of the axial length of the shaft 7 between the first slope 4 and the second slope 5 is set to, for example, 2: 8 to 8: 2. By setting it in this range, when the oil seal is attached to the shaft 7, the second inclined surface 5 can be reliably brought into contact with the shaft 7. However, the ratio of the axial length of the shaft 7 between the first slope 4 and the second slope 5 is not limited to this, and can be changed as appropriate as long as the second slope 5 can be brought into contact with the shaft 7. .

  When the size of the oil seal is a shaft diameter of φ132 mm, the sum of the axial length of the shaft 7 of the first slope 4 and the axial length of the shaft 7 of the second slope 5 is, for example, 0.2 to Although it is preferable to set it as 0.5 mm, it is not restricted to this.

  When the oil seal is attached to the shaft 7, at least the first inclined surface 4 and the second inclined surface 5 come into contact with the shaft 7, and sealing is performed. The third slope 6 may contact the shaft 7 or may not contact. The seal surface angle β of the third slope 6 is an angle at which the main seal lip 1 is established, and is not particularly limited as long as γ ≦ β. The seal surface angle β is, for example, 20 degrees ≦ β ≦ 35 degrees. Further, the axial length of the shaft 7 of the third inclined surface 6 is not particularly limited as long as the main seal lip 1 is formed. Further, since the valley portion 8 between the first inclined surface 4 and the second inclined surface 5 is not in contact with the shaft 7, a space 10 is formed between the valley portion 8 and the shaft 7.

  When the oil seal is attached to the shaft 7, the left side in FIG. 1 is the sealed side (sealed fluid side 2), and the right side is the non-sealed side (unsealed fluid side 3).

  The relationship of the seal surface angles of the first to third inclined surfaces 4 to 6 constituting the seal surface 1a of the main seal lip 1 is α <γ ≦ β, and the relationship to the shaft 7 which is a sliding counterpart member In the mounted state, at least the first slope 4 and the second slope 5 are brought into contact with the shaft 7, so that the configuration of the contact surface with the shaft 7 is the first slope 4 and the seal surface with the seal surface angle γ. A two-stage configuration with the second inclined surface 5 having an angle α is obtained. For this reason, the contact width of the seal surface 1a with the shaft 7 is widened. For example, even if foreign matter is generated inside the device and foreign matter is caught in the first slope 4 on the sealed side, the sealed fluid side 2 and the non-sealed fluid It is difficult for a gap to communicate with the side 3 to be generated, and the sealing performance against foreign matter can be improved.

  In addition, the setting of the seal surface angle γ of the first inclined surface 4 is less likely to affect the increase or decrease in the contact width of the seal surface 1a to the shaft 7, and the degree of freedom in setting the seal surface angle γ can be improved. Therefore, the seal surface angle γ can be increased to reduce the lip tip angle, and the contact pressure of the lip tip 1b to the shaft 7 can be increased to improve the sealing performance in the initial sealing state.

  Thus, both the increase in contact pressure and the increase in contact width, which are in a trade-off relationship, can be achieved at a high level.

  Further, since the space 10 is formed between the valley portion 8 between the first inclined surface 4 and the second inclined surface 5 and the shaft 7, the contact surface of the main seal lip 1 with the shaft 7 is the first surface. A double structure is formed between the slope 4 and the second slope 5. Therefore, the pressure distribution of the seal surface 1a is such that the contact pressure is small in the non-contact portion (the valley portion 8 between the first inclined surface 4 and the second inclined surface 5), and the contact pressure increases as the distance from the non-contact portion increases. For example, as shown in FIG. 4, in the non-contact portion near the valley portion 8 between the first inclined surface 4 and the second inclined surface 5, the contact pressure becomes 0 and the lip tip 1b (first inclined surface) 4) and the peak 9 (the tip of the second slope 5) have the highest contact pressure. Therefore, when the shaft 7 rotates, the air in the space 10 is discharged to both sides (the sealed fluid side 2 and the non-sealed fluid side 3) of the main seal lip 1, and the space 10 becomes negative pressure, and the first slope 4 The second slope 5 is pulled toward the space 10 side. Therefore, the contact pressure between the first inclined surface 4 and the second inclined surface 5 increases, and the sealing performance at the initial stage of sealing can be further improved.

  Further, since the contact surface of the main seal lip 1 with the shaft 7 is interrupted between the first inclined surface 4 and the second inclined surface 5, the contact width of the lip tip 1b (the first inclined surface 4) Contact width) can be reduced, and the contact pressure can be concentrated to further increase the contact pressure of the lip tip 1b. Therefore, the sealing performance in the initial sealing state can be further improved.

  In addition, since the contact surface of the main seal lip 1 with the shaft 7 is doubled so as to be interrupted between the first inclined surface 4 and the second inclined surface 5, a foreign object is caught in one of the inclined surfaces. However, the other inclined surface is in contact with the shaft 7, and it is difficult for a gap to communicate between both sides of the main seal lip 1 (sealed fluid side 2 and non-sealed fluid side 3) to further prevent oil leakage. be able to.

  In addition, since the contact surface of the main seal lip 1 with the shaft 7 has a double structure in which the first inclined surface 4 and the second inclined surface 5 are interrupted, even if foreign matter passes through one of the inclined surfaces. The foreign matter can be received and held in the space 10. Therefore, it is possible to prevent foreign matter from entering the other slope, and also from this point, it is possible to prevent the occurrence of a gap communicating between both sides of the main seal lip 1 and further prevent oil leakage.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the above description, in the mounted state on the shaft 7, the valley portion 8 between the first inclined surface 4 and the second inclined surface 5 is not in contact with the shaft 7. You may make it contact. Also in this case, both the increase of the contact pressure and the increase of the contact width, which are in a trade-off relationship, can be achieved at a high level, and both the sealing performance at the time of foreign object pinching and the initial sealing state can be improved.

(Test 1)
In determining the angles of γ, α, and β, first, γ was set to 20 degrees, which is a lip angle of a general oil seal, and seals with different angles of α were formed, and a sealing test was performed. Note that β is set to 25 degrees because it is better if it is larger than γ.

  Test conditions: Rotation speed of shaft 7: It was operated at 150 rpm for 240 hours. The results are shown in Table 1. Symbol O: No oil leakage, Symbol x: Oil leakage due to foreign matter biting. The axial length of the oil seal at the time of the test is as follows. The axial length of the first slope 4 is 0.2 mm, the axial length of the second slope 5 is 0.3 mm, and the first slope 4 The sum of the axial length and the axial length of the second inclined surface 5 is 0.2 to 0.5 mm in actual size of the oil seal. In addition, the ratio of “the axial length of the first inclined surface 4: the axial length of the second inclined surface 5” is preferably substantially equal, but may be 2: 8 to 8: 2. If it is out of the above range, one of the slopes does not come into contact, and there is a possibility that the sealing performance cannot be secured.

(Test 2)
Next, oil seals with different γ angles were formed, and a sealing test was performed. Here, α is (γ−5) degrees from the above test results, and β is 25 degrees as in the above test.

  Test conditions: Rotation speed of shaft 7: It was operated at 150 rpm for 240 hours. The results are shown in Table 2. Symbol ◯: No oil leakage, symbol Δ: slight oil bleeding, symbol X: oil leakage due to foreign matter biting.

(Test 3)
Based on the above test results, FEM analysis was performed. The result is shown in FIG. Symbol ○: No oil leakage (test result), Symbol △: Slight oil bleeding (test result), Symbol ×: Oil leakage due to foreign object biting (test result), Symbol ◇: No oil leakage (FEM analysis result) □: There is oil leakage (FEM analysis result). In this analysis, in the above test results, the same oil pressure distribution as in the oil seal where no oil leak occurred was regarded as no oil leak, and the same oil pressure distribution as that in the oil seal where oil leak occurred occurred. Then.

  From the above test and FEM analysis results, if γ is 10 ° to 25 ° and α is (γ−2) degree ≧ α ≧ (γ−8) degree, oil leakage due to foreign object biting did not occur. From the test results, if γ is 15 ° to 25 ° and α is (γ-2) degree ≧ α ≧ (γ-8) degree, good sealing can be achieved without slight oil bleeding. I understood.

  Further, it was found that when γ is less than 10 degrees, oil leakage occurs due to foreign object biting. This is considered to be because if γ becomes too small, the contact pressure of the seal lip tip 1b cannot be secured. For this reason, γ is at least 10 degrees or more, more preferably 15 degrees or more.

  When γ is larger than 25 degrees, the second inclined surface 5 with the seal surface angle α does not contact the shaft 7 or even if it is in contact with the shaft 7, it is very weak. It was found that sex cannot be secured.

  If the angle difference between α and γ is greater than 8 degrees, oil leakage due to foreign object biting occurs. This is because the first slope 4 and the second slope 5 intersect when the first slope 4 with the seal face angle γ and the second slope 5 with the seal face angle α are fitted to the shaft 7. The valley portion 8 that is not in contact with the portion becomes large, and the first inclined surface 4 and the second inclined surface 5 do not sufficiently contact the shaft 7, so the contact area of the lip is small, and when the foreign matter is caught, the sealing fluid This is because a gap connecting the side 2 and the non-sealed fluid is formed, causing oil leakage.

  When the angle difference between α and γ is less than 2 degrees, when the first slope 4 and the second slope 5 are fitted to the shaft 7, the first slope 4 and the second slope 5 are It was found that the intersecting portion (the valley portion 8) did not become non-contact. Therefore, α is preferably such that the angle difference between α and γ is 2 degrees or more.

  From the above, it is preferable that the seal surface angle γ is 10 to 25 degrees and the seal surface angle α is (γ−2) degrees ≧ α ≧ (γ−8) degrees, and more preferably, the seal surface angle γ is It was found that the seal surface angle α was (γ−2) degrees ≧ α ≧ (γ−8) degrees at 15 to 25 degrees.

DESCRIPTION OF SYMBOLS 1 Main seal lip 1a Seal surface of main seal lip 1 1b Lip tip 3 Non-sealing fluid side 4 First inclined surface with seal surface angle γ 5 Second inclined surface with seal surface angle α 6 Third inclined surface with seal surface angle β 7 axis 8 Valley between first slope and second slope

Claims (3)

The seal surface of the main seal lip is arranged in order from the tip of the lip to the non-sealing fluid side, a first slope with a seal surface angle γ, a second slope with a seal surface angle α, and a third slope with a seal surface angle β. is constituted by a slope, the respective sealing surface angle alpha, gamma, a relationship between beta is α <γ ≦ β, and wherein at least the first inclined surface second slope into contact with the shaft Oil seal.   The oil seal according to claim 1, wherein a trough between the first slope and the second slope is not in contact with the shaft.   3. The oil seal according to claim 1, wherein the seal surface angle γ is 10 to 25 degrees and the seal surface angle α is (γ−2) degrees ≧ α ≧ (γ−8) degrees. .