JPH0130693Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a mechanical seal that achieves improved assemblability and increased slip torque.

(Prior art) With respect to the rotating shaft 20 shown in FIG.
A mechanical seal with a sleeve having a structure in which the rotary shaft 20 can be simultaneously rotated and fitted onto the outside in a liquid-tight manner has advantages such as being able to prevent corrosion and abrasion of the rotating shaft 20 and making it extremely easy to replace the seal parts.

In this type of mechanical seal, for example, in order to facilitate installation into a pump, a rotary sealing ring 22, an annular packing 23, a reinforcing fitting 24, and a spring 2 are attached to the sleeve 21.
We try to deliver the product as a set with 5 grade seal parts assembled.

By the way, by pushing the rotary sealing ring 22, annular packing 23, reinforcing metal fitting 24, etc. to the left in the drawing against the spring force from the illustrated position where the spring 25 is in a free length state, the pump etc. Although it is assembled, the annular packing 23 is tightly fastened to the sleeve 21 in order to function as a secondary packing. Therefore, the frictional force is large, and the sleeve 21 cannot be assembled unless a lubricant is applied to the outer circumferential surface of the sleeve 21.

(Problem to be solved by the invention) Turbine oil, grease, etc. are used as general lubricants. As shown by characteristic A in FIG. 5, the amount of turbine oil applied tends to decrease over time, although the pressing load immediately after the annular packing 23 is set on the sleeve 21 is small. Therefore, the adhesive force between the inner periphery of the annular packing 23 and the outer periphery of the sleeve 21 gradually increases, which tends to significantly increase the pushing load. Therefore, if several days have passed after installation due to storage or transportation, for example, the pushing load will not decrease even if the turbine oil is reapplied, making assembly work difficult.
There is a risk that the inner circumferential portion of the sleeve 3 may be peeled off and the sealing performance against the sleeve 21 may be deteriorated.

On the other hand, with grease, unlike turbine oil, the applied amount does not decrease over time, so as shown by characteristic B in FIG. 5, the pushing load does not increase over time.

However, as shown by characteristic B in FIG. 6, the slip torque is small. Therefore, the annular packing 2
3 and the sleeve 21, which may reduce the sealing performance therebetween.

The slip torque increases by using turbine oil as a lubricant, as shown by characteristic A in FIG. Cannot be used above.

The present invention was developed in view of these conventional circumstances, and is a mechanical seal that has a small push-in load, improves ease of assembly, and also secures a large slip torque to improve sealing performance. The purpose is to provide.

(Means for Solving the Problems) The mechanical seal according to the present invention has an annular groove formed in the sleeve, and a spring that presses the rotary sealing ring fitted onto the sleeve against the fixed sealing ring and has a free length. In this state, an annular packing interposed between the rotary sealing ring and the spring is configured to correspond to the groove.

(Function) In the present invention, when the spring is in its free length state, the annular packing corresponds to the groove of the sleeve, and the sleeve is not tightened by the inner periphery of the annular packing. Therefore, even if the sleeve is left in the set state for a long period of time, by applying lubricant to the outer periphery of the sleeve immediately before assembly, assembly can be performed with a small pushing load. For this purpose, a lubricant whose slip torque increases over time can be used.

(Embodiment) Fig. 1 is a half-cut sectional view showing a set state of an embodiment of the mechanical seal of the present invention.
A sleeve 2 having one end formed thereon is rotatably and fluid-tightly fitted onto the outside. That is, the sleeve 2 is externally fitted onto the rotating shaft 1 via a coupling member such as a key or a set screw (not shown) so as to be rotatable at the same time.
An O-ring 3 fitted in an annular groove 2B formed on the inner periphery of one end is brought into pressure contact with the outer periphery of the rotating shaft, thereby ensuring sealing between the two 1 and 2 and making them liquid-tight.

Reference numeral 4 denotes a rotary sealing ring 5 which is a rubber annular packing having a substantially L-shaped cross section, and both 4 and 5 are integrally connected in a fluid-tight manner in a state adjacent to each other in the axial direction by an annular reinforcing metal fitting 6. The outer diameter of the axially extending portion 5A of the annular packing 5 is set by a reinforcing metal fitting 6.

Reference numeral 7 denotes a spring, which is interposed between the one end flange 2A of the sleeve 2 and the annular reinforcing metal fitting 6. When the spring 7 is in the free length state shown in the figure, the axially extending portion 5A of the annular packing 5
However, the annular groove 8 formed on the outer periphery of the sleeve 2
corresponds to

As shown in an enlarged view in FIG. 2, the concave groove 8 has a rising surface 8A substantially perpendicular to the axis of the rotating shaft 1 on the front end side, that is, on the rotary sealing ring 4 side, and a rear surface 8A on the rear end side. It has a slope 8B that slopes gently upward.

The angle of inclination α of the inclined surface 8B is preferably in the range of 5° to 20°, and is set to 10° in this embodiment.
The inner peripheral surface 5B of the annular packing 5 has a gap 9 with respect to the groove bottom 8C of the groove 8.

After seal parts such as the rotary seal ring 4, annular packing 5, spring 7 and reinforcing metal fittings 6 are set on the sleeve 2 as described above, it is assembled into, for example, a pump casing 10 as shown in FIG. That is, in the state of FIG. 1 in which the spring 7 is in its free length state, the rotary sealing ring 4 is brought into contact with the stationary sealing ring 11 on the side of the pump casing 10, and then, against the spring force of the spring 7, the rotary sealing ring 4 is further moved as shown in FIG. By pushing the sleeve 2 in as shown, the rotating seal ring 4, annular packing 5, and reinforcing metal fitting 6 are axially moved to the left in the drawing, and the sealing surface 4A of the rotating sealing ring 4 and the sealing surface 11A of the fixed sealing ring 11 are sealed. Along with
By tightening the sleeve 2 with the annular packing 5, a fluid-tight state is achieved.

In the set state shown in FIG. 1, the annular packing 5 corresponds to the annular groove 8 of the sleeve 2 with a gap 9, and the annular packing 5 is not tightened to the sleeve 2. Moreover, when assembled in the state shown in FIG. 3, since an inclined surface 8B that gently slopes upward from the rear is formed in the direction in which the annular packing 5 moves, that is, on the rear end side of the annular groove 8, the first Even if the sleeve 2 is left in the set state shown in the figure for a long period of time, by applying lubricant to the outer peripheral surface of the sleeve 2, the annular packing 5 will move smoothly using the inclined surface 8B as a guide.
As shown by characteristic C in FIG. 5, it can be easily assembled with a small pushing load.

Even if turbine oil is used as a lubricant applied during assembly, assembly can be performed with a small push-in load as described above, and as shown in characteristic A in Figure 6, turbine oil has a tendency to reduce slip torque over time. Since the slip torque increases, a large slip torque can be secured during pump operation.

Further, in the above embodiment, since the distal end side of the annular groove 8 is formed as a rising surface 8A that is substantially perpendicular to the axis of the rotating shaft 1, the axis of the sleeve 2 can be rotated clockwise in the set state shown in FIG. Even in the vertical position rotated by 90 degrees, the inner circumference of the annular seal 5 interferes with the rising surface 8A, so the seal parts, that is, the rotary seal ring 4, the annular seal 5, the reinforcing ring 6, and the spring 7, may fall off. is prevented.

(Effects of the invention) As explained above, according to the invention, when the spring that presses the rotary sealing ring fitted onto the sleeve against the fixed sealing ring is in the free length state, the annular shape formed on the sleeve Since the annular packing is configured to correspond to the groove, the annular packing does not tighten the sleeve in the set state.

Therefore, even if the sleeve is left in the set state for a long period of time, by applying lubricant to the outer circumferential surface of the sleeve immediately before assembling, it becomes possible to assemble with a small push-in load, improving the ease of assembling.

Moreover, by applying a lubricant such as turbine oil, which increases the slip torque over time, to the sleeve, the slip torque during operation increases and excellent sealing performance can be ensured.

[Brief explanation of the drawing]

Fig. 1 is a half-cut sectional view showing an installed state of an embodiment of the mechanical seal of the present invention, Fig. 2 is an enlarged sectional view showing an annular groove, and Fig. 3 is a half-cut sectional view showing an embodiment of the assembled state. 4 is a conventional half-cut sectional view, FIG. 5 is a graph showing the relationship between changes in pushing load and the number of days that have passed since setting, and FIG. 6 is a graph showing the relationship between changes in slip torque and number of days that have passed since setting. It is a graph showing a relationship. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2... Sleeve, 4... Rotating sealing ring, 8... Annular groove, 11... Fixed sealing ring.

Claims (1)

[Scope of utility model registration request] In a mechanical seal in which a sleeve is rotatably and fluid-tightly fitted onto a rotating shaft, an annular groove is formed in the sleeve, and a rotary sealing ring fitted onto the sleeve is pressed against a fixed sealing ring. 1. A mechanical seal characterized in that when the spring is in a free length state, an annular packing interposed between the rotary sealing ring and the spring corresponds to the groove.