Sealing mechanism with metal seal ring

Abstract

A sealing mechanism (1) that seals an annular gap (4) between a housing (2) and a rotation shaft (3) comprises a metal sealing (10). A first shaft sliding surface (15), a labyrinth seal forming surface (16), and a second shaft sliding surface (17) are formed on a circular inner peripheral surface (11) of the sealing (10). The first and second shaft sliding surfaces (15, 17) are matte surfaces having a prescribed surface roughness. A labyrinth seal is formed between the labyrinth seal forming surface (16) and a circular outer peripheral surface (3a) of the rotation shaft (3). Making the first and second shaft sliding surfaces (15, 17) matte surfaces makes it possible to reduce the frictional resistance with the rotation shaft (3) and to suppress wear and heat generation in the first and second shaft sliding surfaces (15, 17). Furthermore, a sealing mechanism capable of preventing oil leakage in both axial directions can be obtained.

Description

[Technical field]

[0001] The present invention relates to a sealing mechanism for sealing an annular gap between a relatively rotatable shaft and a housing. [Background technology]

[0002] Rubber products such as oil seals and packings are widely used as this type of sealing mechanism. The rubber oil seal is attached to the housing side in the annular gap between the housing and the rotating shaft. The seal lip of the oil seal is brought into contact with the outer circumferential surface of the rotating shaft to seal the annular gap and prevent lubricating oil from leaking out of the housing through the annular gap. The contact force of the lip tip against the outer circumferential surface of the rotating shaft is controlled by the pressure of the rubber oil seal body and the spring pressure of a spring arranged inside the oil seal.

[0003] Such a sealing mechanism having a rubber oil seal has the following problems to be solved. (1) Since the rubber seal lip is in contact with the outer peripheral surface of the metal rotating shaft, if the seal lip wears or deteriorates, proper contact cannot be formed, causing oil leakage. (2) To prevent oil leakage, there is a method to increase the tension (tension) applied to the oil seal in the circumferential direction. However, it is difficult to estimate the amount of heat and wear of the oil seal caused by the contact force with the metal (rotating shaft), and therefore it is also difficult to set the tension to an appropriate value. (3) When the oil seal comes into contact with the metal (rotating shaft), frictional resistance occurs, generating heat at the contact point. This heat affects the product characteristics. (4) Because the oil seal comes into contact with the metal (rotating shaft), scratches can occur on the metal, resulting in secondary oil leakage. (5) Conventional oil seals require metal rings and springs, making it difficult to manufacture products that are particularly small and lightweight. (6) The oil seal's oil leakage prevention part (lip part) can only prevent oil leakage in one direction, and is not designed as a basic structure to prevent oil leakage in both directions.

[0004] Here, a sealing device with a seal lip is proposed in Patent Document 1. In the sealing device described in this document, in order to reduce the frictional force caused by the sliding of the rubber seal lip and suppress wear, fine irregularities are imparted to the sliding surface of the seal lip, and grease of a predetermined viscosity is supplied to the sliding surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2012 / 127895 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional sealing mechanisms equipped with rubber lip seals, problems remain such as wear and heat generation on the sliding surface of the lip seal, and the resulting deterioration of sealing performance. In addition, since the contact state of the lip seal with the rotating shaft is formed by spring force, it is not easy to form an appropriate contact state (sealing state). Furthermore, since the wear and heat generation state of the lip seal vary depending on the contact state, it is not easy to maintain an appropriate contact state (sealing state).

[0007] In view of the above, an object of the present invention is to provide a sealing mechanism capable of eliminating the drawbacks of a sealing mechanism equipped with a rubber oil seal. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a sealing mechanism for sealing an annular gap between a relatively rotatable shaft and a housing, comprising: It is equipped with a metal seal ring, The seal ring has an inner peripheral surface formed with a first shaft sliding surface, a labyrinth seal forming surface, and a second shaft sliding surface along an axial direction, the first and second shaft sliding surfaces are surfaces on which the outer peripheral surface of the shaft slides, and matte surfaces are formed over the entire circumferential direction of the first and second shaft sliding surfaces; The labyrinth seal forming surface, located between the first and second shaft sliding surfaces, is characterized in that an annular recess and an annular protrusion are formed which form a labyrinth seal between themselves and the outer peripheral surface of the shaft.

[0009] In the sealing mechanism of the present invention, the shaft sliding surfaces (first and second shaft sliding surfaces) are formed on the inner peripheral surface of the metal seal ring, and the shaft sliding surfaces are matte-finished with a predetermined surface roughness. By matting the shaft sliding surfaces, the frictional resistance between the shaft sliding surfaces and the shaft can be reduced, and wear and heat generation of the shaft sliding surfaces can be suppressed. Also, unlike a rubber oil seal, there is no need to incorporate a metal ring or spring member inside to bring the lip seal into contact with the outer peripheral surface of the shaft, making it easy to reduce the size and weight.

[0010] In addition, in the sealing mechanism of the present invention, the matte-finished shaft sliding surfaces become tiny oil pools when viewed microscopically, and therefore also function as oil leakage prevention sections. A labyrinth seal is formed between the labyrinth seal forming surface located between the shaft sliding surfaces and the outer peripheral surface of the shaft. The labyrinth seal and the oil leakage prevention function of the matte-finished shaft sliding surfaces on both sides prevent oil leakage in both axial directions.

[0011] Here, the sealing mechanism of the present invention further includes a mounting ring attached to the seal ring and positioned between the seal ring and the housing, and the mounting ring is preferably made of an elastically deformable or expandable material. The elastic deformation or expansion of the mounting ring can absorb errors such as dimensional errors, assembly errors, and alignment errors of the shaft, housing, and seal ring. Also, the effects of clearance changes and misalignment between the seal ring and shaft during rotation can be mitigated.

[0012] The matte surface formed on the shaft sliding surface can have a surface roughness of about 3 μm to 15 μm in maximum height Ry. In this case, the gap dimension between the shaft sliding surface of the metal seal ring and the outer circumferential surface of the shaft can be set to 5 μm to 15 μm. Effect of the Invention

[0013] In the sealing mechanism of the present invention, the shaft sliding surfaces (first and second shaft sliding surfaces) formed on the inner peripheral surface of the metal seal ring are matte-finished, and a labyrinth seal is arranged between the shaft sliding surfaces, which makes it possible to suppress wear and heat generation on the shaft sliding surfaces and also to prevent oil leakage in both axial directions. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic half-sectional view showing an example of a sealing mechanism to which the present invention is applied. [Diagram 2] FIG. 2 is an explanatory diagram showing a main part of the sealing mechanism in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of a sealing mechanism to which the present invention is applied will be described with reference to the drawings. As shown in Figs. 1 and 2, a sealing mechanism 1 according to the embodiment is a mechanism for sealing an annular gap 4 formed between a housing 2 and a rotating shaft 3. The sealing mechanism 1 includes a metal seal ring 10 and a rubber or resin mounting ring 20 in an annular shape that is coaxially attached to the outer periphery of the seal ring 10. The mounting ring 20 is disposed between the seal ring 10 and the housing 2. The seal ring 10 is attached to the housing 2 via the mounting ring 20. For the seal ring 10, for example, an SS material (general structural rolled steel material), an SC material (machine structural carbon steel), an SCr material (chromium steel), an SCM material (chromium molybdenum steel), an SNC material (nickel chromium steel), an SNCM material (nickel chromium molybdenum steel), or other steel material is used.

[0016] The seal ring 10 is a ring with a rectangular cross section, and includes a circular inner circumferential surface 11, a circular outer circumferential surface 12, an annular inner end face 13 facing the inside of the annular gap 4, and an annular outer end face 14 on the opposite side. On the circular inner circumferential surface 11, a first shaft sliding surface 15, a labyrinth seal forming surface 16, and a second shaft sliding surface 17 are formed in this order from the inner end face 13 side toward the outer end face 14 along the direction of the axis 1a.

[0017] The first shaft sliding surface 15 and the second shaft sliding surface 17 are circular inner peripheral surfaces on which the circular outer peripheral surface 3a of the rotating shaft 3 can slide. The first shaft sliding surface 15 is a circular inner peripheral surface of a constant width from the inner end face 13 toward the axis 1a, and the second shaft sliding surface 17 is a circular inner peripheral surface of a constant width from the outer end face 14 toward the axis 1a. The first and second shaft sliding surfaces 15, 17 are matte surfaces with a predetermined surface roughness.

[0018] The labyrinth seal forming surface 16 between the first and second shaft sliding surfaces 15 and 17 is formed with two annular recesses 18a and 18b and an annular protrusion 19 located between these annular recesses 18a and 18b. The annular recesses 18a and 18b are rectangular recesses with a constant width and a constant depth, and open to the inner periphery (rotating shaft side). The annular protrusion 19 formed between these annular recesses 18a and 18b is a rectangular protrusion with a constant width and a constant height, and a predetermined gap is formed between the inner periphery of the annular protrusion 19 and the circular outer periphery 3a of the rotating shaft 3. A labyrinth seal is formed between these annular recesses 18a and 18b and the annular protrusion 19 and the circular outer periphery 3a of the rotating shaft 3. The configuration of the labyrinth seal forming surface 16, i.e., the number, width, and height (depth) of the annular recesses and annular protrusions, are not limited to those in the embodiment.

[0019] The circular inner peripheral surface 11 of the seal ring 10 and the circular outer peripheral surface 3a of the rotating shaft 3 are subjected to surface treatments such as nitriding, induction hardening, carburizing, and coating to increase the surface hardness. The circular inner peripheral surface 11 of the seal ring 10 is subjected to matte finish processing after the surface treatment to increase the surface hardness. The matte finish is formed by, for example, shot blasting. Here, depending on the rotation conditions, the outer peripheral surface portion of the circular outer peripheral surface 3a of the rotating shaft 3 facing the seal ring 10 is also matte finished. The matte finish formed on the first and second shaft sliding surfaces 15 and 17 of the seal ring 10 can be a surface with a surface roughness of approximately 3 μm to 15 μm in maximum height Ry. In this case, the gap dimension between the first and second shaft sliding surfaces 15 and 17 and the circular outer peripheral surface 3a of the rotating shaft 3 can be 5 μm to 15 μm.

[0020] Next, the metal seal ring 10 configured as described above is attached to the housing 2 via a mounting ring 20. The mounting ring 20 is a component made of a rubber material or a resin material, and is elastically deformable or expandable. The mounting ring 20 has a cylindrical portion 21 of a constant thickness and an annular end portion 22 of a constant thickness that bends at a right angle from one end of the cylindrical portion 21 and extends radially inward. The cylindrical portion 21 is sandwiched radially between the circular inner peripheral surface 2a of the housing 2 and the circular outer peripheral surface 12 of the seal ring 10, and the annular end portion 22 is sandwiched axially between the circular inner peripheral end surface 2b of the housing 2 and the inner end surface 13 of the seal ring 10.

[0021] The housing 2, the rotating shaft 3, and the seal ring 10 are subject to errors such as dimensional errors, assembly errors, and alignment errors. Furthermore, when the rotating shaft 3 rotates, the gap between the seal ring 10 and the rotating shaft 3 may vary, and the rotating shaft 3 may become misaligned. When the metal seal ring 10 is attached to the circular inner peripheral surface 2a of the housing 2 via a rubber or resin mounting ring 20, the elastic deformation or expansion and contraction of the mounting ring 20 absorbs the errors and reduces the effects of the gap size variations, misalignment, and the like.

[0022] According to the sealing mechanism 1 equipped with the metal seal ring 10 of this embodiment, the problems of the conventional sealing mechanism equipped with a rubber oil seal can be solved, as will be described below.

[0023] (1) Since the rubber oil seal is in contact with the outer surface of the metal rotating shaft, oil leakage will occur if the rubber oil seal wears or deteriorates. In contrast, in the sealing mechanism 1 of this embodiment, the first and second shaft sliding surfaces 15, 17 of the metal seal ring 10, which has been subjected to a high-hardness surface treatment, are matte-finished to prevent wear of these first and second shaft sliding surfaces 15, 17. The matte-finished surface forms tiny oil pools when viewed microscopically, and therefore has the function of preventing oil leakage. Due to the familiarity of the contact between the metals, deterioration does not occur as occurs with rubber oil seals.

[0024] (2) To prevent oil leakage, there is a method to increase the tension (tension) applied to the oil seal in the circumferential direction. However, it is difficult to estimate the amount of heat and wear of the oil seal caused by the contact force with the metal (rotating shaft), and therefore it is also difficult to set the tension to an appropriate value. In contrast, the sealing mechanism 1 of this embodiment does not require control based on a tension force (tension force) in the circumferential direction as in an oil seal, which has the advantage that it is easier to estimate the amount of heat generation and wear.

[0025] (3) When the oil seal comes into contact with the metal (rotating shaft), frictional resistance occurs, generating heat at the contact point, which in turn affects the product characteristics. In contrast, in the sealing mechanism 1 of this example, the first and second shaft sliding surfaces 15, 17 of the metal seal ring 10 are matte-finished, thereby reducing frictional resistance between the first and second shaft sliding surfaces 15, 17 and the rotating shaft 3, allowing for smoother movement and suppressing heat generation in the sliding parts.

[0026] (4) Because the oil seal comes into contact with the metal (rotating shaft), scratches are formed on the metal, which results in secondary oil leakage. The tip of the oil seal lip comes into line contact with the rotating shaft, causing scratches. In contrast, in the sealing mechanism 1 of this example, when the metal seal ring 10 is assembled, lubricating oil is supplied (grease is applied) between the metal seal ring 10 and the circular outer peripheral surface 3a of the rotating shaft 3, thereby preventing the occurrence of "initial wear" and "scratches" due to the fitting of the metal parts together. Furthermore, the first and second shaft sliding surfaces 15, 17 of the metal seal ring 10 are matte surfaces and come into point contact with the circular outer peripheral surface 3a of the rotating shaft 3, thereby suppressing the occurrence of scratches due to sliding.

[0027] (5) Conventional oil seals require a mold to manufacture the rubber part, and it is not easy to change the size. In particular, since the oil seal contains a metal ring and spring parts, it is not easy to make it smaller, and it is difficult to manufacture products that are small and lightweight. In contrast, the sealing mechanism 1 of this embodiment uses a metal seal ring 10. The metal seal ring 10 has no parts built in, so it is less subject to size restrictions. Therefore, it is more advantageous for miniaturization than a rubber seal ring.

[0028] (6) The oil seal's oil leakage prevention part (lip part) can only prevent oil leakage in one direction, and is not designed as a basic structure to prevent oil leakage in both directions. In contrast, in the sealing mechanism 1 of this example, the first and second shaft sliding surfaces 15, 17, which have a matte finish, are in point contact with the circular outer peripheral surface 3a of the rotating shaft 3, and the oil leakage prevention function is non-directional, so oil leakage in both axial directions can be prevented.

Claims

1. A sealing mechanism for sealing an annular gap between a relatively rotatable shaft and a housing, comprising: It is equipped with a metal seal ring, a first shaft sliding surface, a labyrinth seal forming surface, and a second shaft sliding surface are formed on an inner peripheral surface of the seal ring along an axial direction; the first and second shaft sliding surfaces are surfaces on which the outer peripheral surface of the shaft slides, and matte surfaces are formed over the entire circumferential direction of the first and second shaft sliding surfaces; a labyrinth seal forming surface located between the first and second shaft sliding surfaces, the labyrinth seal forming surface having an annular recess and an annular protrusion that form a labyrinth seal between the labyrinth seal forming surface and an outer peripheral surface of the shaft.

2. In claim 1, further comprising: a mounting ring attached to the seal ring and positioned between the seal ring and the housing; The mounting ring is a sealing mechanism formed from an elastically deformable or stretchable material.

3. In claim 2, The mounting ring is a sealing mechanism which is a rubber ring or a resin ring having a portion which is sandwiched between the seal ring and the housing in the radial direction and a portion which is sandwiched between the seal ring and the housing in the axial direction.

4. In claim 1, The matte surface has a surface roughness of about 3 μm to 15 μm in maximum height Ry.

5. In claim 3, The gap dimension between the first and second shaft sliding surfaces and the outer circumferential surface of the shaft is A sealing mechanism that is between 5 μm and 15 μm.

6. In claim 1, further comprising: a mounting ring attached to the seal ring and positioned between the seal ring and the housing; The mounting ring is It is made of an elastically deformable or stretchable rubber material or resin material, a portion sandwiched between the seal ring and the housing in a radial direction and a portion sandwiched between the seal ring and the housing in an axial direction, The matte surface has a surface roughness of 3 μm to 15 μm in maximum height Ry, A sealing mechanism in which a gap dimension between the first and second shaft sliding surfaces and the outer circumferential surface of the shaft is 5 μm to 15 μm.

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