JPS58176498A - Outside flow and balance type mechanical seal for pump - Google Patents

Abstract

PURPOSE:To prevent increase of abrasions of sealing surfaces for both of fixed and rotating rings by a method wherein an interval is constituted between an O-ring and the inner surface of a groove wall opposing to a casing for the setting peripheral groove of the O-ring to attenuate a spring pressure against the sealing surface of the rotating ring. CONSTITUTION:A pump shaft 3 is provided with the rotating ring 9 integrally, rotating in contact with the fixed ring 8 while the first O-ring 13 and the second O-ring 14, contacting with the outer periphery of the pump shaft 3, are fitted into the grooves 11, 12 respectively provided on the inner surface of a tubular body 10. The first setting peripheral groove 11 forms the interval 15 for introducing pressurized water 21 of the casing 1 in-between the wall part 11a of inside end and the first O-ring 13. When the pressure of the pressurized water in a space 15 is increased by some reason, it acts into a direction to resist the pressure of a spring 16, therefore, the rotating resistance of the shaft will never be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an upflow type/balanced mechanical seal for a pump, in which pump pressure liquid is guided to the outer periphery of a fixed ring provided with the sealing surface facing the casing, and a rotary seal that rotates together with the pump shaft is used. In an external wave type mechanical seal in which a ring is brought into contact with the sealing surface of a stationary ring from the casing side for sealing, a spring-loaded rotating ring that loosely fits on the pump shaft and applies the contact pressure is extended toward the casing side. P, J A first fitting circumferential groove and a second fitting circumferential groove are provided in tandem in the axial direction from the casing side on the inner periphery of the mounting cylinder, and a 70th ring contacting the outer periphery of the pump shaft is provided between each groove. The 20th ring is fitted into the 70th ring and the inner surface of the groove wall facing the casing of the first fitting circumferential groove, and an interval is formed between the 70th ring and the inner surface of the groove wall facing the casing of the first fitting circumferential groove, and the pressure that enters the interval is formed. The spring pressure against the sealing surface of the rotary ring is reduced by applying hydraulic pressure to the inner surface of the groove wall,
As the compression pressure of the pump increases, the pressure of the seals in contact with the fixed ring and the spring elasticity increases, and the increase in seal pressure resistance causes wear of the seal surfaces of both rings or increases in operating resistance. The purpose is to prevent this from occurring.

A part of the pressure fluid compressed by the pump is guided to the outer periphery of a fixed ring with its sealing surface facing the casing, and the rotating ring, which rotates with the pump shaft, is brought into contact with the sealing surface of the fixed ring from the casing side. In addition, in an external temperature type/balance type mechanical seal in which the elasticity of a spring acting on the rotating ring is balanced with the pump internal pressure, it is necessary to allow fine axial movement of the rotating ring cylindrical portion. An O-ring is fitted between the inner periphery of the cylindrical part and the circumference of the pump shaft to seal the pressure fluid compressed by the pump, and to enable fine movement of the cylindrical part by spring pressure. The recent trend is to create a structure. Fig. 7 shows an example of this, in which the cylindrical portion C and the rotating ring b tend to vibrate slightly in the axial direction as shown by the arrows, with the O-ring d as the fulcrum, and the pump discharge pressure When there is pulsation in P and S, the pressure of the leaking liquid also pulsates, and the elasticity of spring f causes a subtle change in the surface contact pressure of rotating ring b that is in contact with fixed ring a, producing the above-mentioned microvibration. ,
This causes liquid to leak to the outside. The present invention prevents the above-mentioned micro-vibration of the rotating ring, etc., and reduces the elasticity of the spring, that is, the contact pressure of the rotating ring against the stationary ring, using hydraulic fluid pressure.

An embodiment of the present invention will be described with reference to FIGS. 2-3.

In the figure, / is a casing through which a pump shaft 3 is inserted to rotate a rotor t fixed to the insertion part, and a rising mechanical seal chamber 2 is formed by bulging outward at the center of the side surface through which the pump shaft 3 is inserted. Then, the housing S is attached to the casing lP-B so as to cover the seal chamber 2, and the outer end of the pump shaft 3 is rotatably supported by the bearing B.

On the outside inner surface of mechanical seal chamber 2, there is a pump and Attach the support ring 7 with an inner diameter that allows the shaft 3 to pass through it a little loosely. A fixing ring r is provided on the inner surface or is integrally formed.

Further, a rotary ring 9 that contacts and rotates with respect to the fixed ring r is integrally provided on the pump shaft 3, or a mounted cylinder 10 is slightly fitted into the cylinder, and a casing/ Viewed from the direction of the inner first fitting circumferential groove // and the outer second fitting circumferential groove //! are arranged in the axial direction, and between them //, /, ! A first O-ring/3 and a twentieth ring/41' which are in contact with the outer periphery of the pump shaft 3 are respectively fitted into the pump shaft 3. Those O-rings /3, /4' are 70 mm in diameter of the pump shaft 3.
Use one that is at least twice as thick.

P, 7 The first fitting circumferential groove l/ is for forming an interval /j between the inner end wall part //a and the first O-ring /3 to allow the pressurized water, 2/ of the casing l to enter. Make the groove width a little larger.

The interval IS may be approximately 0.3 to 0.0 mm. /l is a spring that is connected between the rotor t and the cylinder 10 and presses the rotating ring 9 against the fixed ring, thereby generating a sealing pressure, and is designed to adjust the sealing pressure and the specified pressure of the pressure water 21. It should be a balanced type.

In the balance type mechanical seal illustrated above, the pressure of the pressure liquid 2/ is the plane (I), (1), (Ill) of FIG.
However, in the present invention, the pressure water 21 entering the interval /j causes the wall part /
It also occurs between the outer surface (■) (described above) and the inner surface (■) of /a. Therefore, the water pressure in the interval / also acts on the surface (V) of the first O-ring 13, but since the first O-ring 13 corresponds to a circular cross section, the pressure is hardly dispersed on the surface (V). The 10th ring/3 has little to do with the pressure balance, and the sealing pressure of the rotary ring 9 against the stationary ring is kept in an appropriate balance by the pressure balance of each of the surfaces (I) to (M). In this way, excessive rotational resistance pressure is not generated on the sealing surfaces of both rings r and 9.

However, if the pressure on the discharge side of the casing//a rises abnormally for some reason, and the pressure of the pressure water 15 also rises, the pressure acting on the inner surface (N') of the wall//a will increase. acts in a direction that counteracts the pressure of the spring 2/6, so the sealing pressure is rather reduced in proportion to the pressure of the pressure water 2/2, and the rotational resistance is not increased.

P, 9 The present invention has the configuration illustrated above, and the inner periphery of the cylindrical portion 10 of the rotary ring 9 has two first
Since the O-ring 13 and the 20th ring lψ are fitted, by making sure that the fitting interval between both O-rings 13 and /'l is as sufficient as possible in the axial direction, the relationship between the cylindrical portion 10 and the rotating ring 9 in FIG. This device is capable of preventing the micro-vibrations described above, and even if there is pulsation in the compressed hydraulic pressure of the pump, it causes uneven compression of the spring 12 partially, and the micro-vibrations cause the rotation ring 9 to move against the fixed ring. The pressure water 2/ is effectively prevented from leaking to the outside from between both rings r and 90 by partially making the surface contact pressure uneven. In addition, the inner surface of the wall portion //a closest to the casing l of the first fitting circumferential groove // which is provided in the closest relationship to the inner space of the casing l on the inner circumference of the cylindrical portion 10 is fitted into the groove l/. P, 10 When the pressure water 21 that enters the gap 15 provided in front of the 70th ring/3 is applied, and the pump pressure increases abnormally, the pressure water 2/ is released by the spring/ Since the pressure of No. 4 is applied in the direction of reducing or canceling it, the rotational resistance pressure of the sealing surfaces of the rotating ring 9 and fixed ring g increases due to the abnormal pressure of the pump, and in the most extreme case, the pump becomes unable to operate. It has the effect of preventing

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional side view of the central part showing the configuration of a conventional riser type mechanical seal, Fig. 2.3 shows an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional side view of the main part, and Fig. 3 is a vertical cross-sectional side view of the main part. The figure is an enlarged side view of the same part. l→casing, λ→outer flow mechanical seal chamber 3→pump shaft, 7→support ring, g→→fixed ring, p, // 9→rotating ring, 10→cylindrical portion, //→first fitting circumference groove,/
/a-wall, 12-second fitting circumferential groove, 13->10th ring, /≠->20th ring, /j->interval, 16->spring, 21
→Pressure water OC Figure 3

Claims (1)

[Claims] Pressure fluid of the pump is guided to the outer periphery of a fixed ring provided with a sealing surface facing the casing, and a rotating ring that rotates together with the pump shaft is brought into contact with the sealing surface of the fixed ring from the casing side for sealing. In an external wave type mechanical seal, a first fitting circumferential groove and a second fitting circumferential groove are formed on the inner periphery of the mounting cylinder extending toward the casing side of a rotating ring fitted with a spring that loosely fits on the pump shaft and applies the above-mentioned contact pressure. A first O-ring and a twentieth ring contacting the outer periphery of the pump shaft are respectively fitted into the six grooves, and a first O-ring and a first fitting groove are provided in tandem in the axial direction from the casing side. P, 2 A gap is formed between the circumferential groove and the inner surface of the groove wall facing the casing, and the pressure liquid entering the gap is applied to the inner surface of the groove wall to cause the pressure of the pressure liquid to enter the gap. A rising/balanced mechanical seal for the pump shaft, which is characterized by reduced splash pressure on the sealing surface.