JPH0128373Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pressure boosting device for maintaining the internal pressure of a seal box to which a mechanical seal is attached above a certain level.

[Conventional technology]

When a mechanical seal is used as a shaft sealing device for a pump or the like, it may be necessary to conditionally increase the pressure in the inner circumferential space of a seal box in which the mechanical seal is mounted. This is because when the pressure in the inner circumferential space of the seal box falls below a certain level, problems such as insufficient lubrication of the sliding surface of the mechanical seal occur due to the relationship with the temperature of the sealing liquid, which reduces the sealing performance and durability of the mechanical seal. This is because it has a negative impact on

For the above reasons, conventionally, as shown in FIG. 2, for example, a housing b formed with a seal box a is provided with a flushing liquid inlet hole d that communicates a pressure source (not shown) with an inner circumferential space c of the seal box. On the other hand, a floating ring e that is in close contact with the housing b side is attached to a part of the mechanical seal M in the inner circumferential space c that is on the inside of the machine, and the inner circumferential surface of the floating ring e and the rotation axis f are attached.
A slit g is provided between the outer circumferential surface of the rotary ring h and the inner circumferential surface of the shaft hole of the housing b. Alternatively, as shown in FIG. By providing a gap g between the A pressure booster is used to maintain the seal box inner circumferential space c at a high pressure above a certain level.

[Problem that the invention attempts to solve]

However, in the above-mentioned pressure booster, a stationary body (floating ring e or housing b) in which the slit g that causes pressure loss faces each other in the radial direction is used.
and a rotating body (rotating body f or rotating ring h), so when these stationary bodies and rotating bodies come into contact due to shaft runout, etc., the flow passage cross-sectional area of the gap g increases due to wear of both. Therefore, there is a risk that the pressure increase value in the inner circumferential space c of the seal box may decrease, and this poses a problem that may cause trouble in the mechanical seal M, which performs a sealing function under appropriate pressure increase conditions.

[Means for solving problems]

In view of the above-mentioned problems, the present invention was devised to provide a pressure boosting device for a seal box that ensures an appropriate pressure boost value.
While drilling a flushing liquid inlet hole that communicates the pressure source with the inner circumferential space of the seal box,
A second part is installed on the inside of the mechanical seal.
The second mechanical seal is equipped with a flushing liquid outlet hole having a small flow passage cross-sectional area that communicates the outer circumferential side and the inner circumferential side of the sealing element constituting the second mechanical seal.

[Effect]

In the above-mentioned pressure booster, from the outer circumferential side (or inner circumferential side) of the second mechanical seal toward the inner circumferential side (or outer circumferential side), in other words, from the inner circumferential space of the seal box to the inside of the second mechanical seal, The flow rate in the flushing liquid outflow hole, which flows towards the space where the flushing liquid flows, is not affected by the rotational vibration of the rotating shaft, etc., so it is possible to always obtain a reliable increase in pressure into the inner circumferential space of the seal box. .

〔Example〕

Next, one embodiment of the present invention will be explained with reference to FIG.

In the drawing, reference numeral 1 denotes a pump housing, and on the outside A side of a seal box 2 formed in the shaft hole, there is an annular stationary side sealing element 4 airtightly supported by the housing 1, and a seal box 2 formed in the shaft hole of the pump. Mechanical seal M ₁ as an original shaft sealing device consisting of an annular rotary-side sealing element 5 airtightly supported on a rotary shaft 3 in a hole.
Further, the housing 1 is provided with a flushing fluid inflow hole Fi that communicates an external pressure source (not shown) with a portion near the mechanical seal _M1 in the inner circumferential space B of the seal box 2. Reference numeral M ₂ denotes a second mechanical seal as a pressure booster mounted on the inside of the mechanical seal M ₁ as a shaft sealing device. It is elastically biased by a floating seat 8 which is a stationary side sealing element that is prevented from rotating, and a coil spring 11 that is airtightly supported on the rotating shaft 3 via an O-ring 9 and whose rear end is supported by a collar 10. The floating seat 8 has an outer periphery 8' side (inner periphery space B side of the seal box 2) and an inner periphery 8'' side (second mechanical seal). The required number of flushing fluid outflow holes Fo are equally spaced in the circumferential direction to communicate with the machine interior space C side of _M2 , and the total cross-sectional area of the flow passages is equal to the flushing fluid inflow hole Fi.
is set lower than that of .

The pressure booster with the above configuration has a flushing liquid inlet
The fluid injected from Fi into the seal box inner circumferential space B flows through the flushing liquid outflow hole Fo into the machine inner space C.
The pressure in the inner circumferential space B is increased by the flow resistance when the flushing fluid passes toward the flushing fluid, and the flow rate in the flushing fluid outflow Fo is not affected by the axial runout rotation of the rotary shaft 3, etc. Although some leakage is observed from the sliding surfaces of the floating sheet 8 and the seal ring 12, the amount is so small that its influence on the pressure increasing effect can be completely ignored.

[Effect of idea]

As is clear from the above explanation, the present invention has a flushing liquid outflow hole that causes pressure loss due to flow resistance in order to increase the pressure inside the seal box.
This is installed in a different mechanical seal installed on the inside of the machine, which is the original shaft sealing device, so that the flushing liquid outflow hole does not wear out due to shaft vibration, etc., and always maintains an appropriate pressure increase value. Therefore, it is possible to prevent troubles such as insufficient lubrication of the mechanical seal as the shaft sealing device due to a pressure drop in the seal box.

[Brief explanation of the drawing]

FIG. 1 is a half-cut sectional view showing an embodiment of the present invention;
FIGS. 2 and 3 are half-cut sectional views showing conventional structures, respectively. 1...Housing, 2...Seal box, 3
... Rotating shaft, 8 ... Floating seat, 12
... Seal ring, B ... Inner circumferential space of seal box, Fi ... Flushing liquid inlet hole, Fo ... Flushing liquid outflow hole, M ₁ ... Mechanical seal,
M ₂ ...Second mechanical seal.

Claims (1)

[Scope of utility model registration request] A flushing liquid inlet hole is bored in the housing forming the seal box to which the mechanical seal is mounted, and a flushing liquid inlet hole is provided to communicate the pressure source with the inner circumferential space of the seal box. A second mechanical seal is installed, and a flushing liquid having a flow path cross-sectional area smaller than that of the inlet hole is provided, and the outer circumferential side and the inner circumferential side of the floating sheet or other sealing element constituting the second mechanical seal are communicated with each other. A seal box pressurization device characterized by having an outflow hole.