JPS632701Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a mechanical seal as a shaft sealing device, and more specifically, to a high-speed mechanical seal used under high-speed operating conditions, the present invention aims to reduce leakage of sealing fluid and wear of seal sliding materials. The purpose is to achieve stable sealing performance.

Conventionally, a mechanical seal as shown in FIG. 1 has been known, and its configuration is as follows.
That is, 1 is a rotating shaft supported in a shaft hole 3 of a housing 2, a part of which is shown, and includes a rotating side component attached to the rotating shaft 1 side and a stationary side component attached to the housing 2 side. The mechanical seal is constructed by: Reference numeral 4 denotes a rotary-side sealing element that is fitted onto the rotary shaft 1, and the annular stepped portion 7 of the rotary shaft 1 is tightened by tightening a nut 6 through a sleeve 5 having an appropriate length in the axial direction.
is hermetically fitted. Reference numeral 8 denotes a fixed side sealing element which forms a sealing sliding surface 9 at an end face opposite to the rotating side sealing element 4, and is fitted into the housing 2 via a retainer 10. Reference numeral 11 denotes a coil spring that elastically biases the stationary side sealing element 8 toward the rotating side sealing element 4 side via the retainer 10, and this elastic bias applies an appropriate surface pressure to the sealing sliding surface 9. will now be granted. 12
and 13 are O-rings for airtightness.

The mechanical seal having the above structure seals the fluid a sealed on the left side in the figure with the sealing sliding surface 9, and the fitting of the rotating side sealing element 4 to the rotating shaft 1 is perpendicular and concentric. The rotary shaft 1 is finished with high precision in terms of angle, parallelism, etc., and a similarly high precision rotary-side sealing element 4 is fitted into the rotary shaft 1.

However, when this type of mechanical seal that tightens the rotating side sealing element 4 against the rotating shaft 1 is installed and used in equipment that rotates at high speed, the mechanical seal itself has high rigidity and absorbs little vibration energy, so the rotating shaft Use near the critical speed (1) or large vibrations when passing through the critical speed may cause failure of the sliding surface 9, resulting in abnormalities such as leakage of the sealing fluid a or damage to the sealing elements 4 and 8, resulting in poor sealing performance. It had the disadvantage that the value was significantly reduced.

In view of the above points, the present invention provides a high-speed mechanical seal that prevents leakage of the sealing fluid and damage to the sealing element (sliding material) that occur at critical speeds of the rotating shaft, and has extremely good sealing performance. The purpose is to

Therefore, the basic structure of the present invention is to provide a gap or an elastic material between the rotating shaft and the rotating side sealing element to absorb vibration energy during the rotation.

Hereinafter, one embodiment of the present invention will be described with reference to FIG.
A rotary-side sealing element 4 having a substantially rectangular cross section is externally fitted onto the annular step 7 of the rotor. The rotary side sealing element 4 is prevented from being pulled out from the rotary shaft 1 by tightening the nut 6 against the end of the rotary shaft 1 through a sleeve 5 having an appropriate length.
The tightening is performed between the rotating side sealing element 4 and the annular step 7.
It is stopped at a position where a slight gap 14 in the thrust direction is formed between the end walls, and when the assembly is completed, it is pressed by the fixed side sealing element 8 and comes into contact with the end wall of the annular step 7. When fluid pressure is applied, the rotation side sealing element 4 is connected to the sleeve 5 due to the difference in pressure receiving area.
It moves toward the fixed side sealing element 8 until it comes into contact with , and as a result, a gap 14 is formed again. Further, the inner diameter of the rotary-side sealing element 4 is slightly larger than the outer circumference of the bottom wall (outer circumferential surface having a small diameter) of the annular step 7, and a slight radial gap 15 is formed in the middle. . Reference numeral 16 denotes a dowel pin fixed to the end wall of the annular stepped portion 7, which engages with the recess 17 on the back surface of the rotary side sealing element 4 to prevent relative rotation between the rotary side sealing element 4 and the rotating shaft 1. is configured. 8
is a stationary side sealing element which forms a sealing sliding surface 9 at an end face opposite to the rotating side sealing element 4, and is fitted into the housing 2 via a retainer 10. Reference numeral 11 denotes a coil spring that elastically urges the stationary sealing element 8 toward the rotating sealing element 4 via the retainer 10, and applies appropriate surface pressure to the sealing sliding surface 9 by its elasticity. I come to do it. 12 and 13 are O-rings for maintaining airtightness.

The high-speed mechanical seal having the above structure is intended to seal the fluid a sealed on the left side in the figure. During operation (rotation), the fluid a presses the rotation-side sealing element 4 from the back side and The oil flows into the gaps 14 and 15 in both the thrust direction and the radial direction, forming an oil film (having a substantially annular shape). Therefore, according to the high-speed mechanical seal,
It is possible to absorb and reduce vibrations generated in the rotating shaft 1 and propagated to the sealing sliding surface 9, and it is possible to stabilize the sealing sliding. It should be noted that both the clearances 14 in the thrust direction and the radial direction,
The design value of 15 varies somewhat depending on the equipment and conditions of use, but is preferably about 0.03 to 0.3 mm.

Next, referring to FIG. 3, another embodiment of the present invention will be explained with respect to only the parts that are different from the first embodiment (FIG. 2). Gap 1 formed between elements 4
4 and 15 are further formed with annular grooves, and a radial spring 18 and a thrust spring 19 are interposed as elastic members in the grooves. The springs 18 and 19 work together with the fluid oil film formed in the gaps 14 and 15 to absorb and reduce vibrations. In this embodiment as well, means for preventing appropriate relative rotation between the rotating shaft 1 and the rotating sealing element 4 is provided.

The present invention has the above-mentioned configuration, and as rotating equipment becomes larger and faster, it is used near critical speeds and vibrations of the rotating shaft when passing through critical speeds are becoming increasingly severe. Since the vibration is reduced by the oil film formed between the rotating shaft and the rotating side sealing element, stable sealing performance can be obtained even under high-speed conditions. Furthermore, according to the present invention, vibration can be reduced simply by regulating the amount of tightening of the rotary-side sealing element, so assembly is very simple.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention.
The figure is a half-cut sectional view showing a conventional mechanical seal, and FIGS. 2 and 3 are half-cut sectional views showing different embodiments of the high-speed mechanical seal of the present invention. DESCRIPTION OF SYMBOLS 1... Rotating shaft, 2... Housing, 3... Shaft hole, 4... Rotating side sealing element, 5... Sleeve, 6
... Nut, 7 ... Annular step, 8 ... Fixed side sealing element, 9 ... Sealing sliding surface, 10 ... Sleeve, 1
1... Coil spring, 12, 13... O-ring, 14, 15... Gap, 16... Knock pin,
17... recess, 18, 19... spring.

Claims (1)

[Scope of utility model registration request] A rotating side sealing element that is externally engaged with the annular step of the rotating shaft, and a stationary side sealing element that is fitted onto the housing side with or without a retainer and is elastically biased in the direction of the rotating side sealing element. In a high-speed mechanical seal that forms a fluid seal at a sealing sliding surface facing the rotating shaft, the inner diameter of the rotating-side sealing element is formed to be slightly larger than the outer diameter of the rotating shaft, and the inner diameter of the rotating-side sealing element is formed to be slightly larger than the outer diameter of the rotating shaft. A radial gap is provided between the rotational shaft and the rotational sealing element, and when fluid pressure is applied, the rotational sealing element moves toward the stationary sealing element due to the difference in pressurized area, thereby creating a space between the rotational shaft and the rotational sealing element. A high-speed mechanical seal characterized by a gap formed in the thrust direction.