JPH0755012A - Shaft sealing device for electric motor - Google Patents

Abstract

PURPOSE:To provide a shaft sealing device in which sealing function can be fulfilled over a wide range from a nonrotating state through a low-speed rotating state up to a high-speed rotating state as the shaft sealing device of an electric motor. CONSTITUTION:A shaft sealing device is constituted in such a way that a stationary rim 32 is provided to the end part of a stator housing 14, and a rotating rim 34 is provided to the shaft end region 20a of an output shaft 20 so as to form a labyrinth between both rims, and also a sealing member 38 having a tongue-shaped part is provided to the rotating rim 34 so as to be integrally rotatable with the rotating rim 34, so that shaft sealing can be performed by an oil seal effect up to a prescribed rotating speed. At a rotating speed exceeding the prescribed rotating speed, sealing function by a labyrinth is fulfilled, and also a speed region in which both the sealing functions are doubly affected is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal device for waterproofing and dustproofing an electric motor used as a drive motor for machine tools and the like, and more particularly to a shaft sealing device which is uniform over a wide rotation range from a low speed range to a high speed range. The present invention relates to a shaft sealing device that exhibits a shaft sealing function and protects the inside of the motor body from the outside.

[0002]

2. Description of the Related Art It is well known to provide a shaft sealing device in a rotating machine having a rotating shaft, especially in a motor.
A shaft seal device is installed in the shaft end area of the output shaft to prevent foreign matter such as dust from outside the machine and liquids such as machining fluid and lubricating oil at the machine tool site, etc., from entering the narrow area inside the motor body and inside the bearing. It is well known to prevent deterioration of the motor function.

As a shaft sealing device for a conventional motor, particularly, an electric motor, the motor is 5,000 r.p.m. p. In the case of a motor that rotates in a relatively low speed range up to about m, a seal holding portion is provided in the stator housing immediately outside the rotary bearing, and the seal holding portion is made of acrylic rubber, nitrile rubber, fluororubber, or the like. A structure in which an oil seal, which is made by sintering and fixing a rubber material on a metal frame, is press-fitted and the oil seal is kept in contact with the surface of the rotary output shaft to prevent foreign matter and contamination source liquid from entering from the outside. Was taken.

On the other hand, when the motor rotates in a so-called high-speed rotation range, a pair of rotating and non-rotating metal is respectively provided on the output shaft carrying the motor rotor in the central portion and the position immediately adjacent to the rotary bearing of the stator housing. The block-shaped body is attached or integrally formed, and a well-known labyrinth consisting of a labyrinth-shaped gap is formed by both block-shaped bodies, and foreign matter and contamination source liquid intrude from the outside while the motor is rotating, in a non-contact state. Was taken in the labyrinth region.

[0005]

However, when the former shaft seal device using an oil seal is applied to a high-speed rotation motor, the oil seal is heated by frictional heat at the lip portion where the oil seal contacts the rotary output shaft. The sealing characteristics will deteriorate over time, and the sealing function will deteriorate due to wear.
The durability is extremely low, and there is a problem of lack of practicality.

On the other hand, in the latter shaft sealing device using the labyrinth, since the pair of block-shaped bodies are provided in a non-contact type, the intruding object passing through the labyrinth can be prevented at a high speed and the shaft sealing function can be improved. On the other hand, it has the drawback that it does not have a sealing function when the motor is stationary or when the motor rotates in the low speed rotation range. Therefore, an object of the present invention is to provide a shaft sealing device for an electric motor capable of reliably generating a sealing function in a wide rotation range from a low speed rotation range to a high speed rotation range. is there.

[0007]

In view of the above-mentioned object, the present invention forms a contact type sealing means in the low speed range of a motor and a non-contact type sealing means in the high speed range of the motor. A single sealing means is provided which exerts a uniform sealing function over the stationary and low-to-high speed rotation range of the motor, and is provided in the shaft end region of the rotation output shaft.

That is, according to the present invention, in the shaft sealing device provided between the stator housing of the electric motor and the shaft end region of the rotary output shaft, the rotary rim provided in the shaft end region of the output shaft and the rotary rim. A labyrinth forming means formed of a stationary rim provided at an end of the stator housing facing the rim, and a shaft end of the output shaft formed between the rotating rim and the stationary rim of the labyrinth forming means. An annular seal chamber disposed on the circumference of the region, a base portion housed in the annular seal chamber and integrally fixed to the rotating rim or the output shaft, and the stationary rim are contacted from a stationary speed to a predetermined speed. To seal the inside of the stator housing and tongue-shaped seal portion centrifugally separated from the stationary rim in a high speed region exceeding the predetermined speed. Electric motor shaft seal device is provided configured Te.

[0009]

According to the above construction, in the low speed region of the motor, the tongue-shaped seal portion of the seal means comes into contact with the stationary rim of the labyrinth forming means in the low speed region so that the tongue-shaped seal portion from the outside of the motor into the inside of the motor. Blocks and seals communication, and in the high speed region, the tongue of the sealing means is separated due to centrifugal action and wears,
While preventing heat generation, the labyrinth formed by the rotating rim and the stationary rim can prevent foreign matter and contamination source liquid from entering the motor from outside the machine.

In the above structure, the weight means for accelerating the function of separating from the stationary rim by the centrifugal action when the rotary output shaft reaches the desired speed range is disposed on the tongue portion of the sealing means, It may be configured to adjust the separating action of the tongue.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the embodiments shown in the accompanying drawings. FIG. 1 is a partial sectional view showing a shaft sealing function of an electric motor provided with a shaft sealing device according to the present invention in a low speed rotation state, and FIG. 2 is a part showing a shaft sealing function of the electric motor in a high speed rotation state. Sectional view, Figure 3
1 is an enlarged view of portion A of FIG. 1, FIG. 4 is an enlarged view of portion B of FIG. 2, and FIGS. 5A and 5B show another embodiment of the shaft sealing device according to the present invention. FIG. 6 is a graph showing the characteristics of the shaft sealing device for an electric motor according to the present invention.

Referring to FIGS. 1 and 2, an electric motor 1
0 is a cross-sectional view of a front half portion of the electric motor 10. The electric motor 10 has a cylindrical stator housing 14 that houses a stator winding 12, and a bearing holding portion at an end of the stator housing 14. An output shaft 20 having a rotor 18 at its center is rotatably provided via a rotary bearing 16 (a front bearing in a pair of front and rear) seated and held by 14a.

According to the present invention, the shaft sealing device 30 is provided on the outer side of the bearing holding portion 14a in the end region of the stator housing 14 and on the shaft end region 20a of the output shaft opposed thereto.

Here, the coaxial sealing device 30 has a stationary rim 32 which is substantially integrally formed in the region of the bearing holding portion 14a of the stator housing 14 which is a stationary element, and the stationary rim 32 is a disc portion. 32a and a tubular portion 32b,
The tubular portion 32b is provided to be opposed to the outer peripheral surface of the shaft end region 20a of the output shaft 20 via an annular micro gap, and to be partially opposed to a rotary rim described below via an annular micro gap.

On the other hand, the shaft end region 20a of the output shaft 20 is provided with a substantially integrally formed rotary rim 34. The rotary rim 34 includes a radial disc portion 34a and an outer peripheral region of the radial disc portion 34a. An annular portion 34b projecting in the axial direction, the outer peripheral surface of the annular portion 34b being between the inner peripheral surface of the tip of the stator housing 14 and the portion of the stationary rim 32 facing the disc portion 32a. Each of them is opposed to each other through an annular micro void. That is, the stationary annular rim 32 and the rotating rim 34 described above form the labyrinth of the above four annular microgaps, and when the rotational speed of the output shaft 20 of the electric motor 10 reaches a high speed, the stator housing 14 is fed from the outside of the motor body. It shuts out dust and water entering the inside of the bearing and the rotary bearing 16 and water and oil that may be intruded from the surrounding motor use environment, and performs both a dustproof and waterproof function.

The stationary rim 32 of the shaft sealing device 30 described above is also used.
And the inner chamber 36 surrounded by the rotating rim 34,
A seal member 38 made of a synthetic rubber material similar to a conventionally known oil seal element is fixedly attached. This seal member 3
8 has an annular base portion 38a and a tongue portion 38b, is fixed to the annular portion 34b of the rotary rim 34 by the base portion 38a, and is provided so as to be rotatable integrally with the rotary rim 34. The tongue portion 38b is The base 38a is hung from the one end of the stationary rim 32 toward the outer peripheral surface of the tubular portion 32b of the stationary rim 32 in a cantilever manner so as to be in contact with the outer peripheral surface. Here, as shown in FIG. 1, the tongue-like portion 38b of the seal member 38 elastically contacts the outer peripheral surface of the tubular portion 32b of the stationary rim 32 when the electric motor 10 rotates at a low speed, and the inside of the inner chamber 36. Isolates and seals the outside and inside of the motor.

Then, as shown in FIG. 2, the electric motor 1
When the output shaft 20 of 0 reaches a high speed region exceeding a predetermined rotation speed, a centrifugal force proportional to the material density of the seal member 38 acts on the tongue portion 38b of the seal member 38 that rotates integrally, Therefore, the tongue portion 38b extends in the circumferential direction,
As a result, the radius of the tongue portion 38b with respect to the motor rotation axis is expanded. As a result, the tubular portion 32 of the stationary rim 32 that the tongue portion 38b of the seal member 38 was in contact with during rotation at low speed.
Separate from b. Therefore, the tongue portion 38b of the seal member is
Is maintained in a non-contact state with the stationary rim 32 during high-speed rotation, so that there is no fear of heat generation or wear.

As described above, while the electric motor 10 is rotating in the high speed rotation range, the sealing action of the seal member 38 is lost, but the above-mentioned four minute portions formed by the stationary rim 32 and the rotating rim 34 are formed. In the labyrinth consisting of the annular gap, a sufficient sealing function is exhibited by high-speed rotation, and dust, water, oil, etc. are prevented from entering from the outside of the motor machine into the inside of the motor machine.

3 and 4 respectively show enlarged states of the sealing action of the seal member 38 of the shaft sealing device 30 in the contact type in the low speed rotation range of the motor. In this way, the seal member 38 comes into contact with the tubular portion 32b of the stationary rim 32 to contact the inner chamber 3
Since the outside of the body of the electric motor 10 is reliably shut off by the inside of the body of the electric motor 10 at 6, the shaft is naturally sealed even when the rotation of the motor is stopped, and dustproofing and waterproofing are performed.

Further, in FIG. 4, the tongue portion 38b of the seal member 38 is separated from the stationary rim 32 to maintain the non-contact state in the high speed rotation range, while the labyrinth shaft seal is achieved therebetween. I understand what is done.

FIG. 5 shows another embodiment of the shaft sealing device 30 according to the present invention. This embodiment is described with reference to FIGS.
Is different from the embodiment of FIG.
A mass body 40 made of a metal or an appropriate resin material is embedded in the tongue-shaped portion 38b of the tongue-shaped portion 3b so as to positively adjust and change the material density of the seal member 38, and the tongue-shaped portion 3 during high-speed rotation
The centrifugal force effect acting on 8b is adjusted so that the boundary area between the contact type shaft seal and the non-contact type shaft seal in the low speed rotation and the high speed rotation of the electric motor 10 is considered in consideration of the speed range of the practical motor. This is so that it can be adjusted to an appropriate speed point.

In this case, the mass of the mass body 40 itself is experimentally obtained in advance in correspondence with the switching speed from the contact type shaft seal to the non-contact type shaft seal, and the seal member 38 is synthesized. At the stage of molding with a rubber material, it is embedded and sealed in the seal member 38. Then, as shown in FIG. 5, in the molding process, if the tongue-shaped portion 38b of the seal member is previously distributed and arranged at equal intervals on the circumference, centrifugal force acts evenly on the circumference, It is possible to cause the separating action of the tongue portion 38b of the seal member 38 in the set rotation speed range.

In FIG. 6, the horizontal axis represents the number of revolutions of the electric motor 10 per unit time, and the vertical axis represents the centrifugal force. The seal member 38 of the shaft sealing device 30 according to the change in the number of revolutions is the stationary rim 32. It is a curve showing the situation of separating from the side. In FIG. 6, a point P at points P, Q, and R on the curve is the rotation speed at which the labyrinth formed by the stationary rim 32 and the rotating rim 34 starts the shaft sealing function, and the sealing member 38 at the rotation speed. The acting centrifugal force is at a relatively low level, and the tongue portion 38b still exhibits the contact type sealing function.

Further, at the point Q, the tongue-shaped portion 38b of the seal member 38 of the shaft sealing device 30 starts to separate from the tubular portion 32b of the stationary rim 32 due to the gradual increase of the centrifugal force accompanying the gradual increase of the rotation speed, and , Indicates the point where the contact sealing function is lost. Further, the point R indicates a limit allowable peripheral speed point at which the sealing function can be maintained when the seal member 38 of the shaft sealing device 30 is not separated from the tubular portion 32b of the stationary rim 32.

In the present invention, the rotational speed position Q at which the seal member 38 deviates from the contact state with the stationary rim 32 is between the start speed point P of the labyrinth sealing and the allowable peripheral speed point R of the seal member 38. Electric motor 10 by setting
Is used in a wide speed range from a stationary state to a high speed rotation range, the contact type sealing by the seal member 38 of the shaft sealing device 30 and the non-contact type sealing by the labyrinth are sequentially operated, and the motor machine body It is possible to achieve dustproofness and waterproofing inside the motor body to the outside. As apparent from FIG. 6, since the shaft sealing function by the contact-type sealing and the non-contact type sealing acts redundantly between the points P and Q, there is no interruption time of the sealing function, Therefore, a highly reliable shaft seal device can be constructed.

In the embodiment shown in FIG. 5, the rotational speed position of the point Q can be adjusted appropriately in consideration of the practical rotational speed of the motor. Although the shaft sealing device provided on the front side of the electric motor 10 is shown in the drawing, it goes without saying that a similar shaft sealing device is also provided on the rear end side.

[0027]

As is apparent from the above description, the shaft sealing device for an electric motor according to the present invention, when the electric motor is used as a drive motor for a machine tool, rotates from a stationary state of zero rotation speed to a high speed rotation. Since the oil seal type contact type sealing action and the labyrinth type non-contact type sealing action function sequentially and redundantly throughout the machining process, the electric motor is highly reliable in waterproof and dustproof performance. Can be exerted under sex.

Therefore, the life of the electric motor can be extended, and the application of each electric motor can be expanded.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view illustrating a shaft sealing function of an electric motor including a shaft sealing device according to the present invention in a low speed rotation state.

FIG. 2 is a partial cross-sectional view illustrating a shaft sealing function of the electric motor in a high speed rotation state.

FIG. 3 is an enlarged view of a portion A of FIG.

FIG. 4 is an enlarged view of portion B in FIG.

FIG. 5A is a partial cross-sectional view showing another embodiment of the shaft sealing device according to the present invention. (B) is the arrow C- of (a)
It is sectional drawing by C.

FIG. 6 is a graph showing the characteristics of the shaft sealing device for an electric motor according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Electric motor 12 ... Stator 14 ... Stator housing 16 ... Rotating bearing 20 ... Output shaft 30 ... Shaft sealing device 32 ... Stationary rim 34 ... Rotating rim 36 ... Inner chamber 38 ... Seal member 40 ... Mass body

Claims (1)

[Claims] 1. A shaft sealing device provided between a stator housing of an electric motor and a shaft end region of a rotary output shaft, wherein a rotary rim provided in the shaft end region of the output shaft and the stator facing the rotary rim. A labyrinth means formed by a stationary rim provided at an end of the housing, and a labyrinth means formed between the rotating rim and the stationary rim, and arranged on a circumference of a shaft end region of the output shaft. An annular seal chamber that is housed in the annular seal chamber and is integrally fixed to the rotating rim or the output shaft and the stationary rim from a stationary speed to a predetermined speed to seal the inside of the stator housing. And a sealing means having a tongue-shaped seal portion that is centrifugally separated from the stationary rim in a high speed range exceeding the predetermined speed. A shaft sealing device for a dynamic motor.