JP3008177U - Self-excited vibration prevention mechanism of mechanical seal - Google Patents

Abstract

(57) [Abstract] [Purpose] To absorb self-excited vibration in the torsional direction on the sealing sliding surface S of the mechanical seal 10 and prevent the generation of noise called seal squeal. A ring-shaped mass body 21 is provided on a seal ring 14 urged by a coil spring 12 via a vibration-proof elastomer member 22, and a vibration-damping / damping system 20 including the ring-shaped mass body 21 and the vibration-proof elastomer member 22 is provided. By setting the natural frequency in the frequency range of the self-excited vibration of the seal ring 14, the self-excited vibration of the seal ring 14 due to the stick-slip on the sealing sliding surface S is absorbed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a mechanical seal for sealing the circumference of a rotary shaft of various devices, which prevents self-excited vibration of the mechanical seal.

[0002]

[Prior art]

 For example, a mechanical seal used as a shaft sealing device in a water pump for circulating engine cooling water of an automobile with a radiator generally has a structure as shown in FIG. In the figure, reference numeral 1 is a water pump housing, and 2 is a rotary shaft which is inserted into a shaft hole of the housing 1 and rotates an impeller (impeller) 3. The mechanical seal 10 has a ring-shaped case 11 that is tightly fitted in the shaft hole opening of the housing 1 and has one axial end opened, and is rotatable in the case 11 by axially movable and loose fitting engagement portions 11a and 14a. A seal ring 14, which is a fixed sliding ring that is supported in a fixed state and is kept airtight from the case 11 by a bellows 13 that is axially biased by a coil spring 12 and is made of an elastomer. A mating ring 16 that is a rotary sliding ring that is held by the boss portion of the impeller 3 that is integral with the rotary shaft 2 and a cup gasket 15 and is axially opposed to the seal ring 14. There is. That is, in this mechanical seal 10, the non-rotating seal ring 14 on the housing 1 side is pressed by the urging force of the coil spring 12 against the mating ring 16 that rotates integrally with the rotating shaft 2 to make sliding contact therewith. In the sealing sliding surface S formed between 12 and 16, the liquid W to be sealed in the pump chamber on the outer peripheral side is prevented from leaking to the atmosphere A side (bearing side).

[0003]

[Problems to be solved by the device]

 A mechanical seal that seals a low-viscosity liquid such as water like the mechanical seal 10 described above has hitherto produced a jarring rubbing noise called "seal noise" on the sealing sliding surface S. Problems such as occurrence have been pointed out. Explaining this further, the lubrication state on the sealing sliding surface S changes depending on the viscosity Z of the liquid to be sealed, the rotation speed N, and the axial load P, and when the value of ZN / P is large, good lubrication is achieved by liquid lubrication. Whereas the lubrication state is obtained, when the liquid to be sealed is low clay, the value of ZN / P becomes small and the liquid film existing on the sealing sliding surface S becomes thin. Lubrication), and the squeal of the seal is likely to occur in this boundary lubrication state.

That is, when the sealing sliding surface S enters the boundary lubrication state and its friction coefficient increases, the seal ring 14 pressed against the mating ring 16 by the coil spring 12 is rotated by the mating ring 16. Due to the friction torque of the sealing sliding surface S, the coil spring 12 and the elastomer bellows 13 urging the seal ring 14 are torsionally deformed by the friction torque of the sealing sliding surface S, and the torsion restoring force due to its elasticity is accumulated. Therefore, when the predetermined torsional displacement amount is reached, the seal ring 14 is returned in the direction opposite to the rotation of the mating ring 16 by the torsional restoring force, and is again torsionally displaced in the rotational direction by the friction torque. Stick-slip motion, that is, self-excited vibration occurs.

Further, since the seal ring 14, and the coil spring 12 and the elastomer bellows 13 that elastically support the seal ring 14 constitute a kind of vibration system, the moment of inertia of the seal ring 14 is increased. Is m ₀ , and the torsion spring constant of the coil spring 12 and the elastomer bellows 13 is k ₀ , the torsion natural frequency ω ₀ of the vibration system is

[Equation 1] Given in. Therefore, for example, in the process of increasing the shaft rotational speed after starting the pump, self-excited vibration of the frequency ω ₀ causes noise such as “googoo”.

The present invention has been made under the circumstances as described above, and its technical problem is to absorb self-excited vibration in the torsional direction at the sealing sliding surface of the mechanical seal and It is to prevent squeaking.

[0007]

[Means for Solving the Problems]

 The above technical problems can be effectively solved by the present invention. That is, the self-excited vibration prevention mechanism for the mechanical seal according to the present invention comprises a non-rotating fixed slide ring mounted on the housing side and an axial direction of the fixed slide ring mounted on the rotary shaft side of the inner circumference of the housing. A rotary sliding ring that is in sliding contact with one end surface; and a spring that axially urges one of the fixed sliding ring and the rotary sliding ring toward the other sliding ring. In a mechanical seal including: an annular mass body concentrically arranged on a sliding ring biased by the spring of the fixed sliding ring and the rotary sliding ring; A vibration damping elastomer member elastically coupled to the slidable ring, and the sliding ring biased by the spring to the natural frequency of the damping system composed of the annular mass body and the vibration damping elastomer member. Is set in the frequency range of the self-excited vibration of .

[0008]

[Action]

Assuming that the moment of inertia of the annular mass is m and the spring constant of the vibration-proof elastomer member in the torsion direction is k, the natural frequency ω _{d in} the torsion direction of the damping system consisting of this annular mass and the vibration-proof elastomer member is

[Equation 2] Given in. Therefore, the natural frequency ω _d of the damping system is determined by the moment of inertia m of the annular mass and the torsional spring constant k of the anti-vibration elastomer member and the frequency range of self-excited vibration of the sliding ring urged by the spring. If this is set to, when self-excited vibration occurs on the sealed sliding surface, this vibration is transmitted and the vibration suppression system consisting of the annular mass body and the vibration-proof elastomer member resonates. Since the displacement has a dynamic damping function that occurs in the direction of canceling the self-excited vibration, the generation of noise is effectively prevented.

[0009]

【Example】

 FIG. 1 shows a preferred embodiment in which the present invention is applied to the mechanical seal 10 for a water pump of FIG. 3 described above. That is, in this embodiment, an annular mass body 21 made of a metal ring is concentric with the outer periphery of the seal ring 14 which is biased toward the mating ring 16 side by the coil spring 12 via the tip flange portion 13a of the elastomer bellows 13. The annular vibration isolating elastomer member 22 is interposed between the inner peripheral surface of the annular mass body 21 and the outer peripheral portion of the seal ring 14. The vibration-proof elastomer member 22 can be formed in an annular shape and press-fitted between the seal ring 14 and the annular mass body 21, or can be adhered by an adhesive or baking during vulcanization molding.

The moment of inertia m of the annular mass body 21 is determined by the inner diameter, outer diameter, axial thickness and material of the annular mass body 21. The torsional spring constant k of the vibration-proof elastomer member 22 is determined by the joint area between the seal ring 14 and the annular mass body 21, the wall thickness, the compression amount, the material, and the like. As a result, the torsional natural frequency ω _{d of the} vibration damping system 20 including the annular mass body 21 and the vibration damping elastomer member 22 is the seal ring 14 and the coil spring 12 that elastically supports the seal ring 14 in the case 11. And the natural frequency ω _{0 in} the torsional direction of the vibration system including the elastoma bellows 13 are set to be substantially the same.

Since the structure of the mechanical seal 10 itself is the same as that of FIG. 3 described above, the description thereof will be omitted. It goes without saying that the annular mass body 21 and the vibration-proof elastomer member 22 are provided so as not to come into contact with the housing 1, the impeller 3, or the like in the mounted state shown in the drawing.

According to this embodiment, even if self-excited vibration due to stick-slip motion of the seal ring 14 on the sealing sliding surface S of the mechanical seal 10 occurs, this self-excited vibration in the torsional direction is It is absorbed by the dynamic vibration damping action of the vibration damping system 20 including the body 21 and the vibration damping elastomer member 22. That is, as shown in FIG. 2, when the frequency ω ₀ of the stick-slip motion on the sealed sliding surface S ₁ is substantially equal to the natural frequency ω _{d of the} vibration damping system 20 in the torsional direction, the conventional one shown by a dashed line Self-excited vibration like that of the mechanical seal is suppressed, and the occurrence of "seal noise" is effectively prevented.

The present invention is not limited to the illustrated embodiment. That is, in the above-mentioned embodiment, the mechanical seal 10 is of a stationary type in which the non-rotating seal ring 14 is biased by the coil spring 12, and the annular mass body 21 and the vibration-proof elastomer member 22 are provided. Is provided on the seal ring 14, which is a fixed sliding ring, and a coil spring and a seal ring urged by the coil spring are provided on the rotary shaft side and are rotated together with the rotary shaft. In the mechanical seal, the annular mass body 21 and the vibration-proof elastomer member 22 are provided on the seal ring which is a rotary sliding ring. In this case, the vibration damping system 20 including the ring-shaped mass body 21 and the vibration-proof elastomer member 22 absorbs the self-excited vibration in the torsional direction while rotating together with the seal ring.

Further, in the above-described embodiment, the damping system 20 including the annular mass body 21 and the vibration-proof elastomer member 22 is provided on the outer peripheral side of the seal ring 14, but depending on the shape of the mechanical seal, It can also be provided on the inner circumference side or the back side.

[0015]

[Effect of device]

 According to the present invention, the self-excited vibration in the torsional direction due to the stick-slip motion generated on the sealing sliding surface of the mechanical seal is absorbed, so that the noise from the mechanical seal called "seal noise" is generated. It can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a half sectional view showing an embodiment in which a self-excited vibration preventing mechanism according to the present invention is applied to a mechanical seal for a water pump, cut along a plane passing through an axis.

FIG. 2 is an explanatory diagram showing the relationship between the amplitude and frequency of self-excited vibration of the seal ring in the above embodiment.

FIG. 3 is a half cross-sectional view showing an example of a conventional mechanical seal provided with no self-excited vibration prevention mechanism, taken along a plane passing through an axis.

[Explanation of symbols]

 1 Housing 2 Rotating Shaft 10 Mechanical Seal 12 Coil Spring 14 Seal Ring (Fixed Sliding Ring) 16 Mating Ring (Rotating Sliding Ring) 20 Vibration Suppression System 21 Annular Mass Body 22 Anti-Vibration Elastomer Member

Claims (1)

[Scope of utility model registration request] 1. A non-rotating fixed slide ring mounted on the housing side, and a rotary slide mounted on the rotary shaft side of the inner circumference of the housing and in sliding contact with one axial end surface of the fixed slide ring. A fixed seal ring and a rotary slide ring, and a spring for axially urging one of the fixed slide ring and the rotary slide ring toward the other slide ring. And an annular mass body arranged concentrically with the sliding ring biased by the spring of the rotary sliding ring, and the annular mass body and the sliding ring biased by the spring are elastically connected. A vibration damping elastomer member, and the natural frequency of the damping system consisting of the annular mass body and the vibration damping elastomer member is set to the frequency range of the self-excited vibration of the sliding ring urged by the spring. Self-excited vibration prevention mechanism of mechanical seal.