JPH08232657A - Mechanical seal - Google Patents

Abstract

PURPOSE: To improve sealability of a mechanical seal by setting a seal surface pressure between a carbon ring and a ceramic ring almost equal over a circumferential total unit. CONSTITUTION: In order to obtain a mechanical seal structure of a pump, the structure is formed by setting a pressure acting in a contact surface between a carbon ring 11 and a ceramic ring 15 almost equal over a circumferential total unit and by changing thickness of a seal rubber 14 on a circumference in accordance with distribution of a spring constant on the circumference of a spring 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device for a pump that pumps a fluid, and more particularly to a sealing device that prevents the fluid from entering a support portion of a pump rotating shaft.

[0002]

2. Description of the Related Art A conventional technique will be described below with reference to FIGS. However, the left direction of the drawing will be described as the front direction and the right direction will be described as the rear direction. A water pump for an internal combustion engine
As shown in FIG. 7, the housing 2 is integrally formed with a flange 2a extending outward in the radial direction and has a hollow inside, and has a convex cross-section having a small diameter portion and a large diameter portion. There is. The housing 2 is fixed to the cylinder block 3 by bolts 20 at the flange 2a. In front of the small diameter portion, the rotary shaft 6 is rotatably supported coaxially with the housing 2 via a bearing 7. The bearing 7 is formed on the peripheral surface of the rotary shaft 6 at intervals with grooves 6a and 6b, and on the inner periphery of the outer ring (non-rotating body) 7c so as to face the grooves 6a and 6b. Between the groove 7a and the groove 7a, 7b
It consists of a set of steel balls 7d and 7e. This outer ring 7
A seal plate 21 is disposed on the axial end surface of the outer ring 7c.
The lubricant 8 such as grease sealed inside is prevented from leaking to the outside. The rotary shaft 6 is smoothly rotated by the lubricating action of the lubricant 8. The rotary shaft 6 fixes the impeller 4 in the space formed by the flange 2a and the cylinder block 3 at one end, and an external drive source ( A pulley 5 for transmitting a driving force from (not shown) is provided.

The driving force transmitted through the pulley 5 rotationally drives the impeller 4 fixed to the rotary shaft 6. Due to this rotation, the engine cooling water that flows in from the cylinder block 3 side is compressed and sent out, and a cooling water path formed by the water jacket, the radiator (neither shown) in the cylinder block 3 and the cylinder head, and the water pump 1. It will circulate inside.

In addition to the above construction, a mechanical seal 9
Is fitted between the housing 2 and the impeller 4 in the rear of the small diameter portion of the housing 2 and is fixed to a protruding portion 2b formed at the rear end of the small diameter portion so as to project toward the impeller 4 side. Has been done.

That is, the mechanical seal 9 is
Impeller room A on the impeller side ₁And the support of the rotary shaft 6
Holding part side space A₂Divide into and impeller room A₁Side cooling water
By sealing the supporting part side space A₂Cooling to
Prevents ingress of water and water vapor, and moistens the lubricant in the support part.
It will work to maintain smoothness and durability.

By the way, the mechanical seal 9 has a liquid film formed by bleeding the cooling water on its sealing surface to lubricate the sealing surface. It will penetrate into the side space A ₂ . Therefore, in order to discharge the leaked cooling water to the outside, the housing 2 is provided with a water draining hole 2c and a steam draining hole 2d which communicate with the outside between the support portion of the rotary shaft 6 and the mechanical seal 9. Has been done.

Next, the overall construction of the mechanical seal will be described with reference to FIG. (However, the same numbers are attached to the corresponding parts.)

Reference numeral 10 denotes a case, which is formed as a bottomed double pipe having an inner pipe, an outer pipe, and a bottom portion, and an opening end portion of the outer pipe has an annular flange 10a extending radially outward. ing. Further, a convex portion 10b protruding outward in the axial direction is formed at a part of the open end of the inner pipe. The outer tube outer peripheral surface of the case 10 is coaxially fitted to the rotary shaft 6 so as to contact the inner peripheral surface of the housing 2 behind the small diameter portion of the housing 2, and the flange 10a of the case 10 is connected to the outer peripheral surface of the case 10. The housing 2 is fixed to a protruding portion 2b formed at the rear end of the small diameter portion. A carbon ring 11 which is slidable in the axial direction along the outer peripheral surface of the inner tube of the case 10 is annularly mounted with the concave portion 11a and the convex portion 10b formed on the inner peripheral surface thereof aligned with each other. Further, a gap is provided between the inner peripheral surface of the carbon ring 11 and the outer peripheral surface of the inner tube of the case 10 to reduce the sliding resistance of the carbon ring 11. The matching portion functions as a detent that suppresses relative rotation between the case 10 and the carbon ring 11.

In the case 10, a spring 13 interposed between spring seats 12 is provided, and a seal rubber 14 made of an elastic material having a uniform thickness is provided over the entire circumference. There is. One end of the seal rubber 14 is interposed between the bottom surface of the case 10 and the end surface of the spring seat 12 on the bottom portion side.
The other end is interposed between the end surface of the spring seat 12 on the carbon ring 11 side and the end surface of the carbon ring 11 on the bottom portion side, and adhered by vulcanization or the like. That is, the seal rubber 14 is used for the case 10
The cooling water that flows in serves as a member that prevents the cooling water from passing through the gap between the case 10 and the carbon ring 11 and entering the support portion side space A ₂ . The spring seat 12 prevents the spring 13 from abutting against the seal rubber 14.

Further, a ceramic ring 15 is adhered to the back side of the impeller 4 by vulcanization adhesion or the like via a seal rubber 16 having a uniform thickness over the entire circumference, and is in contact with the carbon ring 11. It is in. This seal rubber 16
Thus, the cooling water passing through the gap between the impeller 4 and the ceramic ring 15 is sealed.

Here, the ceramic ring 15 is brought into contact with the carbon ring 11 by adjusting the axial position of the impeller 4 with respect to the rotary shaft 6 and fixing the impeller 4 to the carbon rubber 11. An elastic force acting in the axial direction is applied, and the combined elastic force of the seal rubber 12 and the spring 13 determines the seal surface pressure at the contact surfaces of the rings 11 and 15.

If the sealing surface pressure is too low, water leakage may occur, whereas if it is too high, the carbon ring 1
When the ceramic ring 15 rotates with respect to No. 1, heat is generated due to friction on the contact surfaces of these rings, and the carbon ring 11 and the ceramic ring 15 partially wear or accelerate the friction, resulting in water. There is a risk of leakage.

Therefore, the rotation of the ceramic ring 15 with respect to the carbon ring 11 is allowed, and the impeller chamber A
_The optimum sealing surface pressure is set to seal the cooling water on the _1st side. As the mechanical seal for the water pump described above, for example, the configuration shown in Japanese Utility Model Laid-Open No. 60-147794 can be mentioned.

[0014]

Here, the spring 1 is used.
Reference numeral 3 is a coil spring, and when it is arranged between the seal rubbers 14, its axial length is cut and adjusted. Further, both ends thereof are subjected to grinding or the like to form flat surfaces perpendicular to the axis. (For example, Figure 2
This is as shown in (b). ) At this time, if both ends are vertical flat surfaces as described above,
When the spring 13 is compressed and fixed in the axial direction, the elastic force of the spring 13 is distributed differently on the circumference.

As described above, due to the synthetic elastic force of the seal rubber 14 and the spring 13, the carbon ring 1
Since the seal surface pressure at the contact surface between the first and the ceramic ring 15 is determined, if the springs 13 having different elastic forces on the circumference are arranged between the seal rubbers 14 having a uniform thickness over the entire circumference. When the ceramic ring 15 is pressed against the carbon ring 11, the synthetic elastic force causes the sealing surface pressure at the contact surfaces of these rings to be distributed differently on the circumference.

Therefore, the carbon ring 11 is supported obliquely with respect to the rotating shaft 6 by the gap between the inner peripheral surface of the carbon ring 11 and the outer peripheral surface of the inner tube of the case 10, and the contact surface rotates. It is not perpendicular to the shaft 6, and it becomes impossible for the carbon ring 11 and the ceramic ring 15 to face each other on the circumference. That is, the carbon ring 11 and the ceramic ring 15 are unevenly worn on their contact surfaces.

The seal rubber 14 receives heat generated when the carbon ring 11 rotates with respect to the ceramic ring 15 via the carbon ring 11 and the case 10, and thus swells or is thermoset. ,
The hardness will change. Due to this change in hardness, the spring constant of the seal rubber 14 in the axial direction changes, and the seal surface pressure at the contact surface changes to either low or high. As described above, if the seal surface pressure is too low, water leakage may occur, and if it is too high, the rings 11 and 15 are unevenly worn on the contact surface, and like the above, the inside of the support portion side space A ₂ There was a risk that cooling water would seep into.

Therefore, an object of the present invention is to make the pressure acting on the abutment surface substantially the same over the entire circumference, or to reduce the elastic force of the elastic body acting on the seal ring, whereby the mechanical force is reduced. This stabilizes the sealing surface pressure of the seal and prevents cooling water from entering the support portion of the rotary shaft.

[0019]

In order to solve the above-mentioned problems, the invention of claim 1 is a rotary shaft having a rotary body at one end and a drive transmission means at the other end, and the rotary shaft and the drive transmission to the rotary body. A housing supported between the holding means, a holding body fitted to the housing, a sealing means provided on the holding body so as to be slidable in the axial direction, and provided between the holding body and the sealing means. Urging means for urging the sealing means toward the rotating body, and rotation that is mounted on the rotating shaft and is rotatable and slidable with respect to the sealing means between the sealing means and the rotating body. A mechanical seal comprising a member, which seals fluid in a liquid-tight manner by bringing the sealing member and the rotating member into contact with each other,
The pressure acting on the rotating member via the sealing means is the same on the contact surface over the entire circumference. According to a second aspect of the invention, a rotary shaft having a rotary body at one end and a drive transmission means at the other end, a housing for supporting the rotary shaft between the rotary body and the drive transmission means, and a housing fitted to the housing. A holding body, sealing means slidably provided on the holding body in the axial direction, and an elastic body provided between the holding body and the sealing means for urging the sealing means toward the rotating body. The seal includes: a biasing unit configured by a spring; and a rotary member that is mounted around the rotary shaft and that is rotatable and slidable with respect to the seal unit between the seal unit and the rotary body. In the mechanical seal for sealing the fluid in a liquid-tight manner by bringing the means and the rotating member into contact with each other, the elastic body is formed of an annular thin film, and the outer end of the thin film is connected to the rotating member of the sealing means. On the side surface excluding the contact surface, The inner end of the thin film characterized by being adhered to the side surface excluding the spring support portion of the holding member.

[0020]

In the invention of claim 1, the sealing means presses the rotating member by the urging force of the urging means, and conversely,
The rotating member pushes back the sealing means by the reaction of the biasing force. That is, the seal ring is brought into contact with the rotating member by the urging action of the urging means, so that the contact surface becomes a fluid sealing surface.

Therefore, the urging force of the urging means determines the surface pressure of the seal surface, and by making the surface pressure the same over the entire circumference of the seal surface, the seal The means is kept perpendicular to the rotation axis, and the contact surface with the rotation member is surely abutted.

According to the second aspect of the invention, when the elastic member receives heat generated when the rotating member rotates with respect to the sealing means and the hardness changes, the spring constant of the elastic member changes. However, the amount of expansion and contraction of the elastic body in the axial direction based on the change in the spring constant is related to the thickness of the thin film. That is, since the film thickness is extremely thin, the amount of change in expansion and contraction of the elastic body in the axial direction due to the change in hardness is small, and the load change of the seal surface pressure at the contact surface between the seal means and the rotating member is minimized. Become.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mechanical seal for a water pump according to the present invention will be described in detail below with reference to FIGS.
However, the description of the same parts as those of the conventional device will be omitted.

In the present invention, the rotating body is the impeller 4, the drive transmitting means is the pulley 5, the holding body is the case 10, and the spring 13 and the seal rubber are the urging means for applying the urging force to the carbon ring 11 as the sealing means. 14
It consists of and. Here, the winding start and the winding end of the spring 13 disposed via the spring seat 12 between the seal rubbers 14 are set at points a as shown in FIG. 2A, for example. Spring 13 at this time
The spring constant on its circumference is distributed differently according to the spring cross-sectional area, as indicated by the broken line in FIG. 2 (c). In this case, the spring constant is highest at point a and lowest at point b.

Further, as shown in FIG.
The urging force acting on the ring 11 should be uniform over the entire circumference.
Of the seal rubber 14 for holding the spring 13
The wall thickness is used as the spring constant distribution on the circumference of the spring 13.
Accordingly, at the point a, the thickness t ₁, Thickness t at point b₂
(T₁<T₂) Is set from point a to point b
The wall thickness is gradually reduced.

As described above, the seal surface pressure at the contact surface between the carbon ring 11 as the seal ring and the ceramic ring 15 as the rotating member is equal to the seal rubber 14
It is determined by the combined elastic force of the spring 13 and the spring 13, and the contact area between the carbon ring 11 and the ceramic ring 15.

The springs 13 have different spring constants distributed on their circumferences. Depending on the distribution of the spring constants, the thickness of the seal rubber 14 is thin at a high spring constant and thick at a low spring constant. Then, by changing the elastic force of the seal rubber 14 on the circumference, the uneven distribution of the spring constant of the spring 13 is corrected, and the combined elastic force of the spring 13 and the seal rubber 14 is changed on the circumference. Has a uniform spring constant distribution at.

Therefore, even if the carbon ring 15 slides in the axial direction, its axis is always kept coaxial with the axis of the rotary shaft 6. That is, even when the ceramic ring 15 presses the carbon ring 11 and surface pressure is generated on the contact surfaces of these rings, this contact surface is supported perpendicularly to the rotary shaft 6, and the surface pressure is This means that the load is uniform over the entire circumference.

Here, FIG. 2C schematically shows the distribution of the spring constant on the circumference, and the broken line indicates the spring 1.
3 shows the spring constant, the shaded portion shows the spring constant of the seal rubber 14, and the solid line shows the combined spring constant of the spring 13 and the seal rubber 14. That is, in order to make the different spring constant distributions on the circumference of the spring 13 uniform over the entire circumference,
By changing the spring constant distribution of the seal rubber 14 on the circumference,
This indicates that the synthetic elastic force is uniform over the entire circumference.

Therefore, the mechanical seal 9 in this embodiment has the seal rubber 14 so that the combined elastic force of the spring 13 and the seal rubber is substantially the same over the entire circumference.
Since the thickness of the carbon ring 11 is changed, the carbon ring 11 and the ceramic ring 15 reliably come into contact with each other, uneven wear is eliminated at the contact surface, and the sealability of the mechanical seal 9 can be improved.

In this embodiment, the seal rubber 1
It is not necessary to change the wall thickness over the entire width direction of 4, and for example, the wall thickness may be changed only between the arrows B as shown in FIG. 5A, or as shown in FIG. On arrow C
The change in wall thickness may be changed only during the period.

Further, since the carbon ring 11 is a rigid body, the biasing force acting on the carbon ring 11 does not necessarily have to be the same over the entire circumference, and the biasing force is the same at opposing positions on the circumference. I wish I had it. For example, the wall thickness of the seal rubber 14 may be changed so that the biasing force is the same only at points a and b in FIG.

Next, the characteristic portion of the mechanical seal of the second embodiment will be described with reference to FIG. However, the same or corresponding components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 3, the seal rubber 14 which is a constituent element of the mechanical seal 9 is formed of an annular thin film, and its outer end portion is formed on the flange 10a of the case 10,
The inner ends are fixed to the end faces of the carbon ring 11 on the bottom side of the case 10 by vulcanization adhesion or the like to seal the cooling water on the impeller chamber A ₁ side. That is, the seal rubber 14 is arranged in the circumferential direction.
Inside the case 10, a spring 13 is provided.
0 and the seal rubber 14 are arranged coaxially with the rotating shaft 6 via a spring seat 12. Here, by pressing the ceramic ring 15 against the carbon ring 11 as in the first embodiment, the spring 13
Gives elasticity to.

As described above, the seal rubber 14 swells or is thermoset by receiving heat due to the rotational friction of the carbon ring 11 and the ceramic ring 15 on the seal surface, and the hardness of the seal rubber 14 changes. Therefore, the spring constant changes.

By the way, when the spring constant of the seal rubber 14 is α, the length is L, and the temperature is T, the expansion / contraction amount ΔL is
It can be represented by ΔL = αLT. That is, the amount of expansion Δ
L is due to the length at the same heat receiving temperature,
The longer it gets, the bigger it gets. Conversely, the amount of expansion and contraction ΔL
The fact that is large means that the spring constant α is small.

Based on the above relationship, when the seal rubber 14 is arranged in the circumferential direction, the expansion / contraction amount ΔL depends on the length in the radial direction and the length in the axial direction. Since the amount of expansion and contraction in the opposite direction is the same in the opposite direction,
It does not contribute to the seal surface pressure. That is, since the amount of expansion and contraction due to the axial length of the seal rubber 14 contributes to the axial movement that affects the seal surface pressure, if the axial length is shortened, the hardness of the seal rubber 14 changes. The load change in the axial direction due to can be reduced. Particularly, in this embodiment, since the seal rubber 14 is a thin film, the change in expansion and contraction in the axial direction is negligible. That is, even if the hardness changes due to heat reception and the amount of expansion and contraction in the axial direction changes, the change in the spring constant of the seal rubber 14 in the axial direction is small, and it hardly contributes to the load change of the seal surface pressure. Become.

Therefore, even when the hardness changes due to the heat received by the seal rubber 14, the change in the spring constant in the axial direction is small, so that the load of the seal surface pressure on the contact surface between the carbon ring 11 and the ceramic ring 15 is small. The change can be minimized, and the sealability of the mechanical seal 9 can be improved. Here, although it is conceivable that the carbon ring 11 is supported obliquely with respect to the rotating shaft 6 by the biasing force of the spring 13, the impeller is kept until the contact surface with the ceramic ring 15 is supported vertically. By pushing in 4 and fixing it, leakage of cooling water is prevented.

In this embodiment, the side surface of the spring seat 12 on the side of the carbon ring 11 is the seal rubber 14.
However, for example, the radial length of the spring seat 12 is extended to the axial center side as shown in FIG. 6, and only the carbon ring 11 is contacted and fixed without contacting the seal rubber 14, Only the elastic force of the spring 13 may act on the carbon ring 11. That is, the seal rubber 14 includes the case 10 and the carbon ring 1.
It suffices that it is arranged so as to seal the cooling water that passes through the gap with the inner peripheral surface of 1.

Further, the spring seats 12 do not have to be arranged at both ends of the springs 13, and may be arranged only on the carbon ring 11 side in order to uniformly apply the elastic force of the springs 12 to the seal rubber 14. .

Next, the characteristic portion of the mechanical seal of the third embodiment will be described with reference to FIG. Similar to the second embodiment, a seal rubber 14 made of an annular thin film is arranged in the circumferential direction, the outer end portion is provided on the flange 10a, and the inner end portion is provided on a side surface of the carbon ring 11 on the support portion side of the rotary shaft 6 respectively. It is fixed by vulcanization adhesion. Further, similarly to the first embodiment, the wall thickness of the seal rubber 14 is changed in the axial direction or the radial direction according to the spring constant distribution of the spring 13, and the combined spring constant of the seal rubber 14 and the spring 13 is made uniform on the circumference of the seal surface. The carbon ring 11 to the ceramic ring 1
It is sure to hit 5.

Therefore, the load change in the axial direction due to the hardness change of the seal ring 12 at the contact surface between the carbon ring 11 and the ceramic ring 15 is minimized.
Since the sealing surface pressure is the same over the entire circumference, the sealing performance of the mechanical seal 9 can be further improved.

According to the present invention, the seal surface pressure of the mechanical seal can be stabilized, and the infiltration of cooling water into the support portion of the rotary shaft can be prevented.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a structure of a spring and a seal rubber according to a first embodiment.

2A is a front view of a spring in the first embodiment, FIG. 2B is a side view of FIG. 2A, and FIG. 2C is a schematic view showing a spring constant distribution of a spring and a seal rubber.

FIG. 3 is a vertical sectional view showing the overall structure of a mechanical seal according to a second embodiment.

FIG. 4 is a vertical sectional view showing the overall structure of a mechanical seal according to a third embodiment.

5 (a) and 5 (b) are longitudinal sectional views showing another embodiment of the mechanical seal of the first embodiment.

FIG. 6 is a vertical cross-sectional view showing another embodiment of the mechanical seal of the second embodiment.

FIG. 7 is a vertical cross-sectional view showing an overall configuration of a water pump according to a conventional technique.

FIG. 8 is a vertical cross-sectional view showing an overall configuration of a mechanical seal according to a conventional technique.

[Explanation of symbols]

4 ... Impeller, 6 ... Rotating shaft, 10 ... Case, 11
..Carbon rings, 13 ... Springs, 14 ... Seal rubber, 15 ... Ceramic rings

Claims (2)

[Claims] 1. A rotary shaft having a rotary body at one end and a drive transmitting means at the other end, a housing for supporting the rotary shaft between the rotary body and the drive transmitting means, and a holding member fitted to the housing. A body, a sealing means axially slidable on the holding body, and a biasing means provided between the holding body and the sealing means for biasing the sealing means toward the rotating body, By providing a rotating member which is mounted on the rotating shaft and is rotatable and slidable with respect to the sealing means between the sealing means and the rotating body, and by bringing the sealing means and the rotating member into contact with each other. In a mechanical seal that seals fluid in a liquid-tight manner, the pressure generated by the urging means and acting on the rotating member via the sealing means is made substantially the same at the contact surface over the entire circumference. A mechanism characterized by Karushiru. 2. A rotating shaft having a rotating body at one end and a drive transmitting means at the other end, a housing supporting the rotating shaft between the rotating body and the drive transmitting means, and a holding member fitted to the housing. A body, a sealing means axially slidable on the holding body, and an elastic body and a spring provided between the holding body and the sealing means for urging the sealing means toward the rotating body. And a rotating member which is annularly mounted on the rotating shaft and which is rotatable and slidable with respect to the sealing means between the sealing means and the rotating body. In a mechanical seal for sealing a fluid liquid-tight by bringing the rotating member into contact, the elastic body is formed of an annular thin film, and an outer end of the thin film is brought into contact with the rotating member of the sealing means. On the side surface except the surface, the thin Mechanical seal, characterized in that it has adhered to the side surface excluding the spring support portion of the holding member inward end of.