JP3605511B2 - Motor with optical encoder - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor with an optical encoder which can be the ambient temperature rises obtain an accurate encoder signal.
[0002]
[Prior art]
2. Description of the Related Art For the purpose of speed control and position control, motors equipped with optical encoders are used in various applications. The optical encoder includes an encoder body that supports non-rotating components such as a light-emitting element, a light-receiving element, and a processing circuit, and an encoder that is rotatably supported by the encoder body via an encoder-side bearing and protrudes from one side wall of the motor case. A rotating shaft connected to the mounting shaft portion, and a rotating plate with a slit attached to the rotating shaft and arranged between the light emitting element and the light receiving element are provided. The optical encoder is configured such that the encoder body is attached to the side wall of the motor case via an encoder fixture having a structure that is deformed with a spring property in the axial direction of the rotating shaft but is not deformed in the circumferential direction of the rotating shaft. Attached to the motor. This encoder mounting member is deformed in response to a change in dimensions due to thermal expansion of the encoder mounting shaft portion generated by heat generation on the motor side and the rotary shaft on the encoder side, thereby preventing excessive force from being applied to the encoder side bearing. Plays a role. An encoder cover having an encoder storage chamber for completely storing an optical encoder and an encoder mounting member is mounted on a side wall of the motor case. The motor-side bearing supporting the encoder mounting shaft is mounted on the side wall of the motor case.
[0003]
[Problems to be solved by the invention]
Conventionally, a protective cover member for protecting non-rotating components has been attached to the encoder body. However, in a motor in which a shaft rotates at a high speed of, for example, 10,000 rotations or more, heat generated by a motor winding and a motor-side bearing that supports the rotating shaft is considerably large. Therefore, if this heat is transmitted to the optical encoder through the rotary shaft on the encoder side, the heat will be trapped inside the protective cover member and the temperature will rise, and the semiconductor components used in the processing circuit will malfunction and correct encoder signals will be generated. No longer available. Then, the inventor considered disposing the optical encoder from which the protective cover member was removed inside the encoder cover.
[0004]
However, even though the temperature of the semiconductor component used in the processing circuit has dropped due to the absence of the protective cover member, it has been found that a problem occurs in which an accurate encoder signal cannot be obtained after a certain period of time.
[0005]
An object of the present invention is to provide a motor with an optical encoder capable of obtaining an accurate encoder signal from the optical encoder disposed in the encoder housing chamber in the encoder cover.
[0006]
[Means for Solving the Problems]
A motor with an optical encoder to be improved by the present invention is an encoder body that supports non-rotating components including a light-emitting element and a light-receiving element, and is rotatably supported by the encoder body via an encoder-side bearing. An optical encoder including a rotary shaft connected to an encoder mounting shaft protruding from the side wall and a rotary plate with a slit mounted on the rotary shaft is used. Here, the slit of the rotary plate with a slit only needs to transmit light, and does not need to be a through hole. The encoder body of the optical encoder is attached to the side wall of the motor case via an encoder attachment having a structure that deforms with a spring property in the axial direction of the rotation shaft but does not deform in the circumferential direction of the rotation shaft. . An encoder cover having an encoder storage chamber for completely storing the optical encoder and the encoder mounting member is mounted on the side wall of the motor case. The motor-side bearing that supports the encoder mounting shaft is mounted on the side wall of the motor case. In addition, a general encoder mounting tool includes a plurality of leaf spring portions arranged at intervals in the circumferential direction of the rotation shaft.
[0007]
In the present invention, between the encoder body and the side wall portion or the inner wall surface of the encoder case, a seal for hermetically partitioning the inside of the encoder storage chamber into a space in which the rotary plate with the slit is located and a space in which the motor-side bearing is exposed. A partition member is arranged. The sealing partition member has a structure that can be deformed in the axial direction in accordance with a change in the distance between the encoder body and the side wall due to thermal expansion of the rotating shaft. Preferably, the sealing partition member is located between the encoder main body and the side wall of the motor case, on the side of the side wall with respect to the encoder mounting member, and contains oil that flows out of the motor-side bearing inside the encoder storage chamber. In order to prevent gas from adhering to the rotary plate with slits, the airtight partition is provided so as to airtightly partition the space where the rotary plate with slits is located from the space where the motor-side bearing is exposed.
[0008]
When the temperature on the motor side rises, the inventor vaporizes and diverges the lubricating oil from the bearing on the motor side, and the gas containing this oil adheres to the slitted rotary plate of the encoder to form a slit through which light is transmitted. Partial blockage has been found to be a major cause of inaccurate encoder signals. Therefore, in the present invention, the partition wall member for sealing is provided to hermetically partition the interior of the encoder storage chamber into a space in which the rotary plate with the slit is located and a space in which the motor-side bearing is exposed, so that oil contained in the motor-side bearing is contained. Gas is prevented from adhering to the rotating plate with slits, thereby preventing generation of an erroneous encoder signal.
[0009]
In addition, the sealing partition wall member is deformed in response to a change in dimensions due to thermal expansion of the encoder mounting shaft portion and the rotary shaft on the encoder side generated by heat generation on the motor side, as in the case of the encoder mounting tool, so that the temperature changes. Even if it does, the sealing effect can be secured. The shape and material of the sealing partition member are arbitrary. However, if the sealing partition member is formed of an elastic material such as rubber, the structure capable of being deformed in the axial direction in response to the dimensional change due to the thermal expansion described above can be simplified. Can be obtained.
[0010]
The sealing partition member may be fixed to at least one of the encoder body and the motor case. However, when the sealing partition member is formed of an elastic material, the sealing partition member is fixed to the encoder body, and the non-fixed side end of the sealing partition member is pressed against the surface of the side wall of the motor case. Is preferred. In this case, the sealing partition member can be mounted at a predetermined position only by performing the work of attaching the optical encoder to the existing motor case, thereby simplifying the assembling work.
[0011]
In order to form the sealing partition member from the elastic material and attach the sealing partition member to the encoder main body side, a rotary shaft is circumferentially surrounded and rotated at a portion of the encoder main body facing the side wall of the motor case. An annular mounting surface extending in the axial direction of the shaft is formed. The sealing partition member is provided with a cylindrical portion fitted to the annular mounting surface and a skirt-like cylindrical portion which spreads so as to increase in diameter as the distance from the cylindrical portion increases. This simplifies the attachment of the sealing partition member to the encoder body and simplifies the shape of the sealing partition member.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a half sectional view of a main part of a motor with an optical encoder having the optical encoder unit of the present invention. FIG. 2 is a perspective view of the optical encoder unit of the present invention. FIG. 3 is a perspective view of a sealing partition member used in the examples of FIGS. 1 and 2.
[0013]
In FIG. 1, reference numeral 1 denotes a high-speed motor that rotates at a rotation speed of 10,000 or more. A high-speed rotation bearing 9 that rotatably supports a motor-side rotating shaft 7 is attached to an end bracket 5 that forms one side wall of the motor case 3. The bearing 9 for high-speed rotation has a structure in which lubricating oil is replenished because oil lubrication (grease) is vaporized and dissipated by heat. An end of the motor-side rotating shaft 7 protruding outward from the end bracket 5 constitutes an encoder mounting shaft 7a.
[0014]
Reference numeral 11 denotes an optical encoder. The optical encoder 11 includes an encoder body 13 that supports non-rotating components including a light-emitting element, a light-receiving element, and a processing circuit, and is rotatably supported by the encoder body 13 via an encoder-side bearing 15 so that an end bracket of the motor case 3 is provided. The encoder includes a rotary shaft 17 on the encoder side connected to the encoder mounting shaft portion 7a protruding from the rotary shaft 5 and a rotary plate 19 with a slit mounted on the rotary shaft 17 on the encoder side. The rotating plate 19 with a slit has a structure in which a coating is applied to, for example, a glass plate to form a plurality of slits. The encoder main body 13 is integrally formed of an insulating resin, and has a through hole 13a at the center where the outer peripheral surface of the encoder-side bearing 15 is fitted. An annular stopper wall 13b is provided integrally with the encoder body 13 at an opening of the through hole 13a on the side of the rotary plate 19 with a slit. The encoder-side bearing 15 is inserted into the through-hole 13a until one end in the axial direction contacts the stopper wall 13b. The other end of the encoder-side bearing 15 in the axial direction is in contact with an annular plate 21 fitted in an annular recess 13c formed so as to surround an opening of the through hole 13a on the motor 1 side. The annular plate 21 is fixed to the encoder main body 13 using a plurality of screws 23.
[0015]
The rotary shaft 17 on the encoder side is provided with a rotary plate 19 having a slit fitted on the outer peripheral portion thereof and fixed thereto, and a rotary plate mounting portion 17b formed with a small-diameter through-hole 17a into which a center bolt 25 is inserted at a central portion, An inner peripheral surface of the encoder-side bearing 15 is fitted to the outer peripheral portion, and a shaft fitting portion 17d provided with a large-diameter through-hole 17c communicating with the small-diameter through-hole 17a at the center. The encoder mounting shaft portion 7a of the rotary shaft 7 of the motor 1 is fitted into the large-diameter through hole 17c. A female screw hole 7b into which the center bolt 25 is screwed is formed in the encoder mounting shaft 7a. An end 17e of the shaft fitting portion 17d of the rotary shaft 17 on the encoder side on the motor 1 side is provided with a gap between the end portion 17e of the annular plate 21 attached to the encoder main body 13 with the screw 23. It is protruding. A U-shaped cutout recess 17f is formed in the end 17e as shown in FIG. An unillustrated mounting screw screwed into a screw hole 7c formed in the encoder mounting shaft portion 7a is fitted into the notched concave portion 17f.
[0016]
An annular stepped portion 13d is formed on the outer peripheral portion of the encoder body 13 on the motor 1 side so as to surround the rotary shaft 17 on the encoder side. The annular step 13d is formed by an annular surface 13e extending in the radial and circumferential directions of the rotary shaft 17 on the encoder side and a cylindrical surface 13f extending in the axial and circumferential directions. As shown in FIGS. 2 and 3, a cylindrical portion 27a of a sealing partition member 27 integrally formed of an elastic material such as rubber is fitted to the cylindrical surface 13f and joined using an adhesive. I have. As shown in FIGS. 2 and 3, the sealing partition member 27 has a cylindrical portion 27a fitted to the cylindrical surface 13f, and a skirt-like cylindrical portion which spreads so as to increase in diameter as the distance from the cylindrical portion 27a increases. 27b. The non-fixed end of the skirt-like tubular portion 27b must be constantly pressed against a wall surrounding a through hole for fixing a bearing formed at the center of the end bracket 5 of the motor 1. . Therefore, the axial length of the skirt-like cylindrical portion 27b and the inclination angle or the spread angle and the elasticity of the rotary shaft 7 on the motor 1 side expand and contract in the axial direction due to thermal expansion, and the encoder body 13 and the end bracket 5 It is determined that the state in which the non-fixed end of the skirt-like tubular portion 27b is constantly pressed against the side surface of the end bracket 5 can be maintained even if the distance to the side surface of the end bracket 5 changes.
[0017]
The optical encoder 11 is housed inside an encoder housing chamber 30 formed inside an encoder cover 29 attached to the end bracket 5 of the motor 1. The encoder cover 29 is provided to protect the optical encoder 11 from dust and the like. The aforementioned sealing partition member 27 is disposed between the encoder main body 13 and the side surface of the end bracket 5, and exposes the space 30 a where the rotary plate 19 with the slit is located and the motor-side bearing 9 inside the encoder storage chamber 30. The space 30b is divided into an airtight space and a space 30b. When the sealing partition member 27 is provided, the gas including the oil component coming out of the motor-side bearing 9 and the dust such as the metal powder coming out of the bearing 9 stop in the space 30b, and enter the space 30a where the rotary plate 19 with the slit is located. Blocked from entering. As a result, it is possible to prevent oil and dust which may block the slits of the rotary plate 19 with slits from adhering to the rotary plate 19 with slits. As described above, the sealing partition member 27 has a structure that can be deformed in the axial direction so as to correspond to a change in the distance generated between the encoder main body 13 and the end bracket 5 due to thermal expansion. Even if 1 rotates at high speed and the temperature rises, the sealing performance does not decrease.
[0018]
The encoder main body 13 is fixed to a side surface of the end bracket 5 of the motor 1 by an encoder fixture 31 formed by processing a metal plate. As shown in FIG. 2, the encoder mounting member 31 is deformed in response to a change in dimensions due to thermal expansion or the like of the encoder mounting shaft portion 7a and the rotary shaft 17 on the encoder side generated by heat generation on the motor 1 side. In order to prevent an excessive force from being applied to the side bearings 15, three leaf spring portions 31a are arranged at intervals in the circumferential or rotational direction of the rotary shaft 17 on the encoder side. As shown in FIG. 2, the three leaf spring portions 31a... Are deformed with a spring property in the axial direction of the rotary shaft 17 on the encoder side, but in the circumferential direction or the rotational direction of the rotary shaft 17 on the encoder side. Does not deform easily. The bases of the leaf spring portions 31a are connected to an annular disk portion 31b. The disk portion 31b is fitted to an annular step portion 13d (FIG. 1) of the encoder body 13 to form an annular surface 13e (FIG. 1). ). Screw insertion holes are formed in the disk portion 31b at substantially equal intervals in the circumferential direction. Then, the screws 33 are inserted into the screw insertion holes, and the encoder fixture 31 is fixed to the encoder body 13. At the distal ends of the three leaf spring portions 31a, mounting legs 31c formed by bending in an L-shape are integrally connected. A screw insertion hole 31d is formed in the mounting portion of the mounting leg portion 31c extending in the radial direction of the rotary shaft 17 on the encoder side, and the screw insertion hole 31d extends in a circular arc shape in the circumferential direction. Then, as shown in FIG. 1, the encoder mounting member 31 is screwed to the end bracket 5 of the motor 1 using screws 35.
[0019]
In FIG. 1, reference numeral 37 denotes a lead wire for guiding the input / output of the optical encoder 11 to a motor control circuit provided in a control box 39. In this example, a cooling fan 41 is mounted outside the encoder cover 29 in the axial direction. The cooling fan 41 cools the encoder cover 29 by blowing air to the outer surface of the encoder cover 29 to prevent the temperature in the encoder storage chamber 30 from rising above an allowable temperature. Although not shown, a ventilation hole is formed in the fan case 43 of the cooling fan 41.
[0020]
In this example, since the sealing partition member 27 is fixed to the encoder main body 13, no special work is required when the optical encoder 11 is mounted on the end bracket 5 of the motor 1 using the encoder mounting tool 31. The sealing partition member 27 can be arranged at a predetermined position, and the non-fixed end of the skirt-like tubular portion 27 b of the sealing partition member 27 can be pressed against the side surface of the end bracket 5. This greatly simplifies the assembly work. It is to be noted that, unlike this example, a sealing partition member may be attached to the motor side and its non-fixed side end may be pressed against the annular surface 13e of the encoder body 13. Further, the sealing partition member may have a bellows structure that expands and contracts in the axial direction of the rotary shaft 17 on the encoder side. In the case where a sealing partition member having a bellows structure is used, the sealing partition member may be fixed to both the encoder and the end bracket of the motor.
[0021]
The sealing partition member may be provided so as to hermetically partition the interior of the encoder storage chamber 30 into a space 30a where the rotary plate 19 with the slit is located and a space 30b where the motor-side bearing 9 is exposed. As shown by a two-dot chain line, an annular sealing partition member 27 ′ may be arranged between the encoder body 13 and the inner wall surface of the encoder case 29. In this case, the outer peripheral portion of the sealing partition member 27 ′ is fixed to the inner wall surface of the encoder case 29 in advance, and when the encoder case 29 is attached to the end bracket of the motor 1, the inner peripheral portion of the sealing partition member 27 ′ is fixed. The surface may be tightly fitted to the outer peripheral portion of the encoder body 13.
[0022]
In the above example, the cooling fan 41 is provided, but the cooling fan 41 is not always necessary.
[0023]
【The invention's effect】
According to the present invention, by providing a sealing partition member to hermetically partition the interior of the encoder storage chamber into a space where the rotary plate with the slit is located and a space where the motor-side bearing is exposed, the oil component etc. Can be prevented from adhering to the rotating plate with slits, so that an erroneous encoder signal can be prevented from being output from the optical encoder. In particular, according to the present invention, when the sealing partition member is formed of an elastic material, the sealing partition member is fixed to the encoder body, and the non-fixed side end of the sealing partition member is a side wall portion of the motor case. The advantage is that the sealing partition member can be mounted in a predetermined position simply by attaching the optical encoder to the existing motor case, thus simplifying the assembly work. Is obtained.
[Brief description of the drawings]
FIG. 1 is a half sectional view of a main part of a motor with an optical encoder according to the present invention.
FIG. 2 is a perspective view of the optical encoder unit of the present invention.
FIG. 3 is a perspective view of a sealing partition member used in the examples of FIGS. 1 and 2;
[Explanation of symbols]
1 motor 3 motor case 5 end bracket (side wall)
7 Motor-side rotating shaft 7a Encoder mounting shaft 9 Motor-side bearing 11 Optical encoder 13 Encoder body 15 Encoder-side bearing 17 Encoder-side rotating shaft 19 Slit rotating plate 27 Sealing partition member 29 Encoder cover 30 Encoder storage room 31 Encoder mounting

Claims (3)

An encoder body supporting a non-rotating component including a light emitting element and a light receiving element, and rotatably supported by the encoder body via an encoder-side bearing and coupled to an encoder mounting shaft protruding from one side wall of the motor case; The encoder main body of the optical encoder including a rotating shaft and a rotating plate with a slit attached to the rotating shaft is deformed with a spring property in the axial direction of the rotating shaft, but in a circumferential direction of the rotating shaft. Attached to the side wall portion of the motor case via an encoder attachment having a structure that does not deform,
On the side wall portion of the motor case, an encoder cover having an encoder storage chamber for completely storing the optical encoder and the encoder mounting member is attached,
A motor-side bearing that supports the encoder mounting shaft portion is a motor with an optical encoder mounted on the side wall portion,
A seal between the encoder body and the side wall portion or the inner wall surface of the encoder case to hermetically partition the interior of the encoder storage chamber into a space where the rotary plate with the slit is located and a space where the motor-side bearing is exposed. Partition member is arranged ,
The sealing partition member has a structure that can be deformed in the axial direction according to a change in the distance between the encoder body and the side wall due to thermal expansion ,
The sealing partition member is formed of an elastic material,
The motor with an optical encoder, wherein the sealing partition member is fixed to the encoder main body, and a non-fixed side end is pressed against a surface of the side wall . An encoder body supporting a non-rotating component including a light emitting element and a light receiving element, and rotatably supported by the encoder body via an encoder-side bearing and coupled to an encoder mounting shaft protruding from one side wall of the motor case; The encoder body of an optical encoder including a rotating shaft and a rotating plate with a slit attached to the rotating shaft, the encoder body including a plurality of leaf spring portions arranged at intervals in a circumferential direction of the rotating shaft. Attached to the side wall portion of the motor case via an encoder attachment having a structure that deforms with spring properties in the axial direction but does not deform in the circumferential direction of the rotating shaft,
On the side wall portion of the motor case, an encoder cover having an encoder storage chamber for completely storing the optical encoder and the encoder mounting member is attached,
A motor-side bearing that supports the encoder mounting shaft portion is a motor with an optical encoder mounted on the side wall portion,
Between the encoder main body and the side wall portion, the gas containing oil which flows from the motor side bearing through the inside of the encoder accommodating chamber is located at a position closer to the side wall portion than the encoder mounting member, and the slit rotation is performed. A sealing partition member for airtightly partitioning a space where the rotary plate with the slit is located and a space where the motor-side bearing is exposed so as to prevent adhesion to the plate is arranged,
The sealing partition member has a structure formed of an elastic material and deformable in the axial direction so as to correspond to a change in a distance generated between the encoder body and the side wall portion due to thermal expansion. ,
The motor with an optical encoder, wherein the sealing partition member is fixed to the encoder main body, and a non-fixed side end is pressed against a surface of the side wall. A cylindrical surface that surrounds the rotating shaft in a circumferential direction and extends in the axial direction of the rotating shaft is formed in a portion of the encoder body that faces the side wall portion,
3. The sealing partition member according to claim 1, further comprising: a cylindrical portion fitted to the cylindrical surface; and a skirt-shaped cylindrical portion that spreads so as to increase in diameter as the distance from the cylindrical portion increases. A motor with an optical encoder as described.

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