JPH0687782U - mechanical seal - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent one-sided contact on the seal surface due to frictional heat generated during operation, and maintain a good seal function. [Structure] A cylindrical deformation member 6 having a coefficient of thermal expansion smaller than that of the ring support member 2 is fitted to the outer periphery of a front end portion of a ring support member 2 that holds a seal ring 1. Alternatively, the front end portion of the ring supporting member 2 is formed with the thermal deformation suppressing member 6 having a thermal expansion coefficient smaller than that of the other portion of the ring supporting member 2 to hold the seal ring 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a means for preventing partial contact due to thermal deformation due to frictional heat generated on the sealing surface of a mechanical seal during operation.

[0002]

[Prior art]

 FIG. 4 shows a conventional mechanical seal. The seal ring 1 is held by the front end portion (right side in the figure) of a tubular ring support member 2. The mating ring 3 is fixed to the rotating shaft 4. The ring supporting member 2 is fitted in the housing 9 so as to be movable in the axial direction, and the seal ring 1 is pressed against the mating ring 3 via the ring supporting member 2 by a spring (not shown). The seal end surface of the non-rotating seal ring 1 and the seal receiving surface of the mating ring 3 that rotates rotate in contact with each other to seal fluid leakage. An annular groove 1c is formed on the seal end surface of the seal ring 1, and fluid supply holes 1h, 2h and 9h communicating with the annular groove 1c are bored. High pressure water is supplied to the fluid supply hole 1h, 2h by a pump or the like not shown. It is sent to the annular groove 1c through 2h and 9h, and a water film is formed between the seal surfaces to reduce frictional resistance loss.

[0003]

[Problems to be solved by the device]

 The conventional mechanical seal is as described above, but frictional heat is generated due to sliding contact between the seal end surface of the seal ring 1 and the seal receiving surface of the mating ring 3 during operation, and as shown in FIG. 3 (B). The temperature of the seal ring 1 rises, and due to thermal expansion, the diameter of the seal ring 1 portion expands to be larger than the diameter of the left portion of the ring supporting member 2 in the figure. As shown in FIG. 3 (B), since the seal end surface also inclines, the inner seal end surface 1i comes into contact with the seal receiving surface of the mating ring 3 and the outer seal end surface 1o separates, and the high pressure water supplied to the annular groove 1c Will easily flow out from the outer seal end face 1o, a water film will not be formed on the inner seal end face 1i, friction will increase and heat generation will increase, and the above tendency will become stronger and eventually burn out. There is a problem It was.

The present invention has been made to solve the above problems, and it is possible to obtain a mechanical seal which prevents uneven contact due to inclination of the seal surface due to thermal deformation during operation, and thus does not increase frictional heat generation. With the goal.

[0005]

[Means for Solving the Problems]

 In the mechanical seal according to the present invention, a thermal deformation suppressing material having a coefficient of thermal expansion smaller than that of the ring strut is fitted around the front end of the ring strut, or the front end of the ring strut is It is formed by a thermal deformation suppressing material having a coefficient of thermal expansion smaller than the coefficient of thermal expansion of the other part of the ring supporting member.

[0006]

[Action]

 In this invention, the thermal deformation suppressing member fitted to the outer periphery of the front end portion of the ring support member of the mechanical seal or the thermal deformation suppressing member forming the front end portion of the ring support member has a smaller coefficient of thermal expansion than the ring support member, so Even if the temperature of the seal ring rises due to the frictional heat of the seal end face, the expansion is small for the temperature rise because it is suppressed by the thermal deformation suppression material, and the ring support does not rise so much because it is far from the friction heat source. The degree of expansion is the same as that of the rear part, and the angle of the seal end face of the seal ring does not change. That is, there is no uneven contact of the sealing surface, and a good sliding contact state of the sealing surface is maintained.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a seal ring, 2 is a ring supporting member for supporting the seal ring 1, 3 is a mating ring with which the seal end face of the seal ring 1 is in contact, 4 is a rotary shaft on which the mating ring 3 is fitted, and 6 is A heat deformation suppressing member fitted to the outer periphery of the front end portion of the ring supporting member 2, and 9 is a casing of a pump or the like to which the mechanical seal is applied. As the seal ring 1, in addition to various metals, calcined carbon, tungsten carbide, silicon carbide, or a combination thereof is used. The front end face (right side in the drawing) of the seal ring 1 is formed as a seal end face so as to obtain an appropriate seal surface pressure, and an annular groove 1c is formed in the radial center portion of the seal end face. The ring support member 2 is formed in a tubular shape so that the portion from the central portion to the rear portion (on the left side in the figure) is axially movably fitted to the inner peripheral surface of a through hole through which the rotary shaft 4 of the housing 9 penetrates. An O-ring is inserted between the inner peripheral surface of the housing 9 and the housing 9 so as to seal the leakage of fluid. The front portion of the ring support member 2 is formed to have a large diameter so as to hold the seal ring 1, and a concave portion for turning the front end face to accommodate the seal ring 1 is formed. A spring (not shown) is provided between the ring support member 2 and the housing 9 so as to push the ring support member 2 to the right in the figure and press the seal ring 1 against the mating ring 3 with an appropriate pressure. Has been. The housing 9, the ring support member 2 and the seal ring 1 are provided with fluid supply holes 9h, 2h and 1h which communicate with the annular groove 1c. High pressure fluid supply means such as a high pressure water pump (not shown) is provided so as to communicate with the fluid supply hole 9h. The annular groove 1c is called a pressure dam.

As shown in FIG. 1, the front portion (right side in the figure) of the ring support member 2 has a large diameter so as to accommodate the seal ring 1, and the thermal deformation suppressing material is provided on the outer peripheral surface of the large diameter portion. 6 is fitted and provided by means such as cold fitting. The thermal deformation suppressing member 6 is made of a material having a small linear expansion coefficient, for example, a low expansion alloy Invar or the like. When the heat deformation suppressing member 6 is fitted to the ring supporting member 2 by a means such as cooling fitting, when the angle of the seal end face of the seal ring 1 changes and the outer diameter side protrudes from the inner diameter side, It suffices to perform a ping process so that the end face of the seal is flat.

As shown in FIG. 1, the mating ring 3 is fitted on the rotary shaft 4 and further fixed to the rotary shaft 4 by a sleeve 8. The end surface on the left side of the mating ring 3 in the drawing is finished by lapping as a smooth flat surface as a seal receiving surface that is in sliding contact with the seal end surface of the seal ring 1.

Next, the operation of the embodiment shown in FIG. 1 will be described. When the rotating shaft 4 rotates, the mating ring 3 that is fixedly rotates together with the rotating shaft 4. The seal ring 1 fitted to the ring support member 2 which does not rotate is propelled by a spring (not shown) so that the seal end surface of the seal ring 1 is pressed against the seal receiving surface of the mating ring 3. The pressing force is the sum or difference of the force of a spring (not shown) and the axial force acting on the ring support member 2 due to the fluid pressure difference between the inside and the outside of the mechanical seal. By thus pressing the seal ring 1 and the mating ring 3 via the ring supporting member 2, the leakage of fluid from the sliding contact surface between the seal ring 1 and the mating ring 3 is sealed.

In the embodiment shown in FIG. 1, an annular groove 1c is formed in the radial center of the seal end surface of the seal ring 1, and through the fluid supply holes 1h, 2h and 9h communicating with this annular groove 1c. Since high-pressure water is supplied from a pump (not shown), when the high-pressure water flows from the annular groove 1c between the outer seal end surface 1o and the inner seal end surface 1i and the seal receiving surface of the mating ring 3, it flows out. A water film is formed between the seal surfaces, and the frictional resistance loss between the seal surfaces is reduced by the same lubricating action as the oil film of lubricating oil.

In FIG. 1, if the seal receiving surface of the mating ring 3 and the seal end surface of the seal ring 1 are in sliding contact with each other, no matter how good the fluid film is formed between the sealing surfaces as described above, the inside of the fluid film There is shear resistance, and if this is considered as a kind of frictional resistance, frictional heat is generated on the seal surface during operation. Due to this frictional heat, the temperature of the seal ring 1 and the front end portion of the ring supporting member 2 holding the seal ring 1 rises. However, since the rear part of the ring support member 2 (on the left side in the figure) is away from the heat source of frictional heat generation, the temperature does not rise much. Therefore, as shown in FIG. 3B, the front portion (right side in the figure) of the ring supporting member 2 expands more than the rear portion (left side in the drawing) of the ring supporting member 2 and the diameter becomes large. The angle of the seal end surface of the seal ring 1 changes, and the inner seal end surface 1i tends to protrude from the outer seal end surface 1o. In the conventional mechanical seal, as shown in FIG. 3B, as described above, the high pressure water supplied to the annular groove 1c easily flows out from the outer seal end face 1o, and A water film was not formed on the seal end surface 1i, friction increased and heat generation increased, and the above inclination became stronger and finally burned.

However, in the embodiment shown in FIG. 1, since the thermal deformation suppressing member 6 is fitted to the outer periphery of the front end portion of the ring support member 2, even if the temperature of the front end portion rises, the thermal expansion coefficient is small. The diameter of the deformation suppressing member 6 does not change so much, and even if the front ends of the seal ring 1 and the ring supporting member 2 try to expand, the diameter is suppressed by the thermal deformation suppressing member 6 as shown in FIG. 3 (A). The diameter of the rear part of the ring supporting member 2 which is not so high as that of the front end part is almost the same as the expansion of the diameter of the rear part of the ring supporting member 2, so that the deformation of the front end parts of the seal ring 1 and the ring supporting member 2 is prevented. It is small, and the change in the angle of the seal end surface of the seal ring 1 is small. Therefore, a good fluid film is maintained between the outer seal end surface 1o and the inner seal end surface 1i and the seal receiving surface of the mating ring 3, and the seal function is maintained without causing burnout due to a small friction resistance loss. To be done.

The thickness and width of the thermal deformation suppressing member 6 are as described above under the conditions of expected temperature change and temperature gradient that occur in the seal ring 1 and the ring support member 2 which are known experimentally. Is determined so that the force of expansion of the front ends of the seal ring 1 and the ring supporting member 2 and the restraining force of the thermal deformation suppressing member 6 are balanced so that the seal end surface of the seal ring 1 does not change in angle. do it.

Next, the embodiment shown in FIG. 2 will be described. In FIG. 2, the thermal deformation suppressing member 6 is directly fitted on the outer peripheral surface of the seal ring 1, and the thermal deformation suppressing member 6 for gripping the seal ring 1 is attached to the front end portion of the ring supporting member 2 for assembly. It has been done. Other configurations are the same as those in FIG. The operation of the embodiment shown in FIG. 2 is the same as that described with reference to FIG. 1, and since the thermal expansion coefficient of the thermal deformation suppressing member 6 is small, the temperature of the seal ring 1 is changed by the frictional heat generated between the seal faces. Since the thermal deformation suppressing member 6 suppresses the deformation even when it rises and expands, as shown in FIG. 3 (A), the angle change of the seal end face of the seal ring 1 is small, and the outer seal end face 1o also has the inner seal. A good fluid film is also formed between the end surface 1i of the ring and the seal receiving surface of the mating ring 3, and the sealing function is maintained without causing burnout due to a small frictional resistance loss.

In the above embodiment, the thermal deformation suppressing material 6 is made of a material having a small expansion coefficient, such as low expansion alloy Invar, but the front surface of the thermal deformation suppressing material 6 or the ring supporting member 2 is made of martens. By using a material having a relatively small expansion coefficient such as site-based stainless steel, and using a material having a relatively large expansion coefficient such as a copper alloy from the central portion to the rear portion of the ring supporting member 2, similar to the above description, The sealing end face of the seal ring 1 is prevented from changing in angle due to thermal deformation, and the sealing function is maintained well. Further, due to the heat of friction between the sealing surfaces, the temperature of the seal receiving surface of the mating ring 3, that is, the portion on the left side of the mating ring 3 in FIG. Therefore, the dimensions of the thermal deformation suppressing member 6 can be determined by positively considering that the seal end surface of the seal ring 1 changes in angle so as to compensate for the change in angle.

In the embodiment shown in FIGS. 1 and 2, the annular groove 1c is formed on the seal end surface of the seal ring 1 and the high pressure fluid is supplied to form the fluid film between the seal surfaces. Even with a mechanical seal that does not have the annular groove 1c, the change in angle of the sealing surface is prevented by providing the thermal deformation suppressing material 6, and uneven contact of the sealing surface is avoided, so that friction heat generation does not increase and seizure etc. The occurrence of damage is prevented.

[0018]

[Effect of device]

 As described above, according to the present invention, the thermal deformation suppressing member fitted to the front end portion of the ring support member suppresses thermal expansion of the seal ring and the front end portion of the ring support member due to frictional heat generation. Therefore, the angle change of the seal surface is prevented, the seal surface is not unevenly contacted, friction heat is not increased, and damage such as seizure is prevented.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a mechanical seal according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a mechanical seal according to another embodiment of the present invention.

FIG. 3A is a view showing deformation of a seal ring and a ring support member of a mechanical seal according to an embodiment of the present invention;
(B) is a diagram showing a deformation of a seal ring and a ring support member of a conventional mechanical seal.

FIG. 4 is a vertical sectional view of a conventional mechanical seal.

[Explanation of symbols]

1: seal ring, 1c: annular groove, 1o: outer seal end surface, 1i: inner seal end surface, 2: ring support member,
3: mating ring, 4: rotating shaft, 6: thermal deformation suppressing material, 1
h, 2h, 9h: Fluid supply holes.

Claims (4)

[Scope of utility model registration request] 1. A mechanical seal for sealing fluid leakage by pressing a seal ring fixedly supported on the front end of a tubular ring support member against a mating ring, wherein the ring is provided on the outer periphery of the front end of the ring support member. A mechanical seal characterized in that a thermal deformation suppressing material having a thermal expansion coefficient smaller than that of a supporting material is fitted. 2. A mechanical seal for sealing a fluid leak by pressing a seal ring fixedly supported on a front end of a tubular ring support member against a mating ring, wherein the front end of the ring support member is a ring support member. A mechanical seal formed by using a thermal deformation suppressing material having a thermal expansion coefficient smaller than that of the other parts of the material. 3. A mechanical seal for sealing a fluid leak by pressing a seal ring fixedly supported on a front end portion of a tubular ring support member against a mating ring, wherein an annular groove is formed on a seal end surface of the seal ring. A high-pressure fluid supply means is provided for supplying a high-pressure fluid through a fluid supply hole that is formed and communicates with the annular groove, and has a coefficient of thermal expansion smaller than the coefficient of thermal expansion of the ring support on the outer periphery of the front end of the ring support. A mechanical seal that is fitted with a thermal deformation suppression material. 4. A mechanical seal for sealing a fluid leak by pressing a seal ring fixedly supported on a front end portion of a tubular ring support member against a mating ring, wherein an annular groove is formed on a seal end surface of the seal ring. A high-pressure fluid supply means is provided for supplying a high-pressure fluid through a fluid supply hole which is formed and communicates with the annular groove, and the front end portion of the ring support member has a thermal expansion coefficient smaller than that of other portions of the ring support member. A mechanical seal characterized by being formed with a thermal deformation suppressing material having an expansion coefficient.