CN212455506U

CN212455506U - Encoder with magnetic fluid seal

Info

Publication number: CN212455506U
Application number: CN202021239920.6U
Authority: CN
Inventors: 朱书雅; 石忠东; 薛颖奇; 付江寒; 仲婷婷; 孟凯; 杨佳明
Original assignee: Beijing Jingdiao Group Co Ltd
Current assignee: Beijing Jingdiao Group Co Ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2021-02-02
Anticipated expiration: 2030-06-30

Abstract

The utility model relates to an encoder with magnetic fluid seal, which comprises a shell, a body bracket, a rotating shaft sleeve, a bearing, a light emitting diode, a code wheel, a sensing chip and a printed circuit board, wherein the shell is fixedly connected with the body bracket; the printed circuit board, the sensing chip, the code disc and the light emitting diode are sequentially arranged from front to back, the printed circuit board is fixed at the front end of the body bracket, the sensing chip is welded on the printed circuit board, the code disc is fixed on the rotating shaft sleeve, and the light emitting diode is arranged on the body bracket; a magnetic fluid sealing device is arranged at the central opening at the front end of the shell and consists of an annular magnet and a magnetic fluid, and the magnetic fluid isolates the interior of the shell from the external environment under the action of magnetic field force of the annular magnet and surface tension of the liquid. The utility model discloses can effectively avoid the frictional heating and the wearing and tearing condition to produce, guarantee measuring result's accuracy, sealed effectual, use cost is low.

Description

Encoder with magnetic fluid seal

Technical Field

The utility model belongs to the technical field of measure, in particular to encoder with magnetic current body seal.

Background

Encoders are widely used as precision measuring devices in the fields of machine tools, semiconductor devices, industrial automation, wind power, and the like. The encoder has high requirements on working environment, especially an optical encoder, if dirt or dust enters the encoder, the signal quality of the encoder is influenced, and even the encoder is stopped due to equipment failure, so that the production is influenced or great property loss is caused. Therefore, the sealing performance of the encoder is an important index for evaluating the performance of the encoder.

Currently, most of the mainstream encoders adopt rubber sealing rings for radial or axial sealing. Because the sealing mode is contact sealing, the sealing ring and the contact part have friction, and when the device runs at high speed or for a long time, the heat generated by the friction can influence the accuracy of the precision measurement result of the encoder to a certain extent; and the sealing device can be worn after long-time operation, oil stains are easy to leak, dust is easy to soak, and the sealing effect is poor. Therefore, in the application field of the grating ruler, a sealing mode combining rubber sealing and positive pressure air blowing sealing appears, and although the sealing mode can ensure a better sealing effect, the positive pressure air blowing sealing needs high-cleanliness compressed air, so that the cost is higher, and the application is limited.

Disclosure of Invention

An object of the utility model is to overcome prior art not enough, provide an adopt the sealed encoder of magnetic current body, can effectively avoid the frictional heating and the wearing and tearing condition to produce, effectively guarantee measuring result's accuracy, improve sealed effect, reduce use cost.

In order to solve the technical problem, the utility model discloses a realize through following technical scheme: an encoder with magnetic fluid seal comprises a shell, a body bracket, a rotating shaft sleeve, a bearing, a light emitting diode, a code disc, a sensing chip and a printed circuit board, wherein the shell is fixedly connected with the body bracket; the printed circuit board, the sensing chip, the code disc and the light emitting diode are sequentially arranged from front to back, the printed circuit board is fixed at the front end of the body bracket, the sensing chip is welded on the printed circuit board, the code disc is fixed on the rotating shaft sleeve, and the light emitting diode is arranged on the body bracket; a magnetic fluid sealing device is arranged at the central opening at the front end of the shell and consists of an annular magnet and a magnetic fluid, and the magnetic fluid isolates the interior of the shell from the external environment under the action of magnetic field force of the annular magnet and surface tension of the liquid.

According to the encoder with the magnetic fluid seal, the annular magnet is magnetized along the radial direction, the annular magnet is fixed at the central opening at the front end of the shell, and the magnetic fluid is filled between the annular magnet and the rotating shaft sleeve.

According to the encoder with the magnetic fluid seal, the annular magnet is magnetized in the axial direction, the magnetic fluid seal device further comprises the magnetizers, the magnetizers are arranged at the front end and the rear end of the annular magnet and fixed at the central opening at the front end of the shell, and the magnetic fluid is respectively filled between the magnetizers and the rotating shaft sleeve.

One or more magnetic fluid sealing devices are arranged on the encoder, and form single-pole sealing or multi-stage sealing respectively; and during multi-stage sealing, the front end face of the shell is of a multi-layer structure, and the magnetic fluid sealing devices are respectively and correspondingly arranged at the central openings of the front end faces of all layers.

Compared with the prior art, the beneficial effects of the utility model reside in that: the utility model discloses a magnetic current body seal structure, rotating part and static part are not direct contact, not only can effectively avoid the sealed frictional heating phenomenon who brings of contact, guarantee the measuring accuracy, but also can effectively avoid wearing and tearing to the influence in life-span, it is sealed effectual to with low costs, the suitability is strong, the range of application is wide.

Drawings

Fig. 1 is a schematic view of the internal structure of the present invention.

Fig. 2 is a schematic view of a single-pole sealing structure of embodiment 1 of the present invention.

Fig. 3 is a schematic view of the multi-stage sealing structure of embodiment 1 of the present invention.

Fig. 4 is a schematic view of the single-pole sealing structure of embodiment 2 of the present invention.

Fig. 5 is a schematic view of the multi-stage sealing structure of embodiment 2 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Example 1.

As shown in fig. 1, the utility model discloses an encoder with magnetic fluid seal comprises casing 1, body support 2, pivot cover 3, bearing 4, emitting diode 5, code wheel 6, sensing chip 7, printed circuit board 8, ring magnet 9 and magnetic fluid 10.

The shell 1 is fixedly connected with the body bracket 2, the rotating shaft sleeve 3 is supported in the body bracket through a bearing 4 and extends out of a central opening at the front end of the shell 1, and the rotating shaft sleeve 3 and the measured rotating shaft can rotate together when being installed. Printed circuit board 8, sensing chip 7, code wheel 6 and emitting diode 5 arrange from the front to back in proper order, printed circuit board 8 is fixed in the front end of body support 2, sensing chip 7 welds on printed circuit board 8, code wheel 6 is fixed in on the pivot cover 3 and rotates along with pivot cover 3, emitting diode 5 sets up on body support 2, the light that emitting diode 5 sent is modulated the back through code wheel 6, shine on sensing chip 7, sensing chip 7 converts the optical information of perception into electrical signal, through resolving to electrical signal, can obtain the positional information of being surveyed the pivot.

The annular magnet 9 is fixed at the central opening of the front end of the shell 1, and the magnetic fluid 10 is filled between the annular magnet 9 and the rotating shaft sleeve 3. The magnetic fluid 10 consists of magnetic particles, a surfactant and a solvent, and the magnetic fluid particles are in a stable dispersion state in the solvent without applying a magnetic field and cannot be condensed or deposited per se; when a magnetic field is applied, the magnetic particles are aligned along the direction of the magnetic field.

Referring to fig. 1 and 2, the ring magnet is magnetized in the radial direction, the magnetic field lines 11 are generated by the ring magnet 9, and the ring magnet 9, the magnetic fluid 10 and the rotating shaft sleeve 3 form a magnetic circuit. The magnetic fluid 10 is limited in the gap between the annular magnet 9 and the rotating shaft sleeve 3 under the combined action of the magnetic field force and the liquid surface tension and cannot be thrown out along with the increase of the rotating speed. Thereby keep apart encoder inside and external environment, and can bear the inside and outside pressure differential of certain intensity to play sealed effect, make code wheel 6, sensing chip 7 avoid the interference of outside greasy dirt and dust.

In the embodiment, the withstand voltage value of the magnetic fluid seal can be adjusted by controlling the magnetizing strength of the annular magnet 9, the magnet width, the gap between the annular magnet 9 and the rotating shaft sleeve 3, the viscosity of the magnetic fluid 10 and the like, so that different sealing effects can be obtained. In addition, the pressure resistance value of the magnetic fluid seal can also be increased by increasing the sealing stage number. Fig. 1 and 2 show a single-pole sealing structure of the present embodiment, fig. 3 shows a multi-stage sealing structure of the present embodiment, taking a two-stage sealing structure as an example, a front end surface of the casing 1 is a double-layer structure, and each layer is correspondingly provided with a group of ring magnets 9 and a magnetic fluid 10 to respectively form two groups of sealing structures.

In the embodiment, the shell 1 is not in contact with the rotating shaft sleeve 3, so that the magnetic fluid 10 part can not generate a large amount of heat and magnetic current when the rotating shaft sleeve 3 rotates at a high speed, and the sealing performance of the magnetic fluid 10 is hardly influenced by the rotating speed of the rotating shaft sleeve 3. In addition, the magnetic particles in the magnetic fluid 10 are distributed in a chain manner along the magnetic field line 11 in the magnetic field formed by the magnet 9, so that a good heat conductivity coefficient is provided between the shell 1 and the rotating shaft sleeve 3, the overall temperature of the encoder tends to be consistent, and the problems of structural deformation and the like caused by temperature difference are avoided. In addition, the radial magnetizing mode of the embodiment enables the magnetic fluid sealing part to occupy a smaller axial space of the encoder, thereby being beneficial to the miniaturization design of the encoder.

Example 2.

As shown in fig. 4, the present embodiment is different from embodiment 1 in that the ring magnet 9 is magnetized in the axial direction, and the front end and the rear end of the ring magnet 9 are fixedly connected with the magnetizer 12 respectively and fixed between two layers of end faces of the casing 1; and a magnetic fluid 10 is filled between the magnetizer 12 and the rotating shaft sleeve 3. The annular magnet 9, the magnetizer 12, the magnetic fluid 10 and the rotating shaft sleeve 3 jointly form a magnetic circuit 11, and the magnetic fluid 10 forms two circles of magnetic fluid sealing rings under the combined action of magnetic field force and liquid surface tension to isolate the external environment from the internal working space, so that the sealing effect is achieved, and the coded disc 6 and the sensing chip 7 are prevented from being interfered by external oil stains and dust.

In the embodiment, the withstand voltage value of the magnetic fluid seal can be adjusted by controlling the magnetizing strength of the ring magnet 9, the magnet width, the gap between the magnetizer 12 and the rotating shaft sleeve 3, the viscosity of the magnetic fluid 10 and the like, so as to obtain different sealing effects. In order to obtain a better sealing effect, the withstand voltage of the magnetic fluid seal can also be increased by increasing the number of sealing stages, as shown in fig. 5, taking two-stage magnetic fluid seal as an example, four magnetic fluid sealing rings can be formed to bear higher external pressure, and if the number of sealing stages is continuously increased, the internal space can achieve the effect of vacuum sealing.

In the embodiment, the leakage flux is less, and the magnetic field between the magnetizer 12 and the rotating shaft sleeve 3 is stronger. In addition, two magnetic fluid sealing rings can exist in the primary sealing, and compared with the embodiment 1, the magnetic fluid sealing ring can bear larger internal and external pressure difference under the same sealing level.

Although the present invention has been described in detail, the present invention is not limited thereto, and those skilled in the art can make various modifications according to the principle of the present invention. Therefore, modifications made in accordance with the principles of the present invention should be understood to fall within the scope of the present invention.

Claims

1. An encoder with magnetic fluid seal is characterized by comprising a shell, a body bracket, a rotating shaft sleeve, a bearing, a light emitting diode, a code disc, a sensing chip, a printed circuit board and a magnetic fluid seal device, wherein the shell is fixedly connected with the body bracket; the printed circuit board, the sensing chip, the code disc and the light emitting diode are sequentially arranged from front to back, the printed circuit board is fixed at the front end of the body bracket, the sensing chip is welded on the printed circuit board, the code disc is fixed on the rotating shaft sleeve, and the light emitting diode is arranged on the body bracket; a magnetic fluid sealing device is arranged at the central opening at the front end of the shell and consists of an annular magnet and a magnetic fluid, and the magnetic fluid isolates the interior of the shell from the external environment under the action of magnetic field force of the annular magnet and surface tension of the liquid.

2. The encoder with the magnetic fluid seal according to claim 1, wherein the ring magnet is magnetized in a radial direction, the ring magnet is fixed at a central opening at the front end of the shell, and the magnetic fluid is filled between the ring magnet and the rotating shaft sleeve.

3. The encoder as claimed in claim 1, wherein the ring magnet is magnetized in an axial direction, the magnetic fluid sealing device further comprises magnetizers disposed at front and rear ends of the ring magnet and fixed at the central opening of the front end of the housing, and the magnetic fluid is respectively filled between the magnetizers and the rotating shaft sleeve.

4. An encoder with magnetic fluid seal according to claim 1 or 2 or 3, wherein the magnetic fluid seal device is one or more, respectively forming a single-pole seal or a multi-stage seal; and during multi-stage sealing, the front end face of the shell is of a multi-layer structure, and the magnetic fluid sealing devices are respectively and correspondingly arranged at the central openings of the front end faces of all layers.