Motor with brake

Abstract

Provided is a motor comprising a sealing structure which can also be arranged in a narrow space while exhibiting a constant sealing function. The motor comprises: a rotatable shaft to which a friction plate is attached; a brake unit that brakes the rotation of the shaft by friction with the friction plate; and a sealing part that suppresses the movement of dust from the brake unit. The sealing part includes: a first sealing member having a first fixed part fixed to the shaft, and a first tapered part which is inclined to the radial outer side and the friction plate side from the first fixed part and extends in a tapered shape; and a second sealing member having a second fixed part fixed to a stationary part of the motor, and a second tapered part which is inclined to the radial inner side and the friction plate side from the second fixed part and extends in a tapered shape, the second sealing member constituting a labyrinth structure in cooperation with the first sealing member.

Description

Motor with brake

[0001] The present disclosure relates to a motor having a brake.

[0002] 2. Description of the Related Art As a motor for driving a rotary shaft of a robot, machine tool, or the like, a motor having a clutch-type brake and an encoder inside, with a rotary disk of the encoder connected to the rotary shaft, is known.

[0003] In brakes with friction plates, such as clutch-type brakes, wear particles are generated during operation, so a technology has been proposed in which a seal structure is provided between the brake and the encoder to prevent the wear particles from causing the encoder to malfunction. Known seal structures include non-contact dust lips and contact oil seals.

[0004] Japanese Utility Model Application Publication No. 63-024966 Japanese Patent Application Publication No. 2021-097430 Japanese Patent Application Publication No. 2021-118622 Japanese Utility Model Application Publication No. 05-057444 Japanese Patent Application Publication No. 2007-198505 Japanese Patent Application Publication No. 2004-080968

[0005] In a structure in which a non-contact dust lip is placed on the shaft, a gap of at least 0.25 mm must be secured between the dust lip and the shaft, which raises the risk of wear debris entering the encoder.On the other hand, if a contact oil seal is used, the wear debris and grease on the oil seal itself can cause the encoder to malfunction, so the use of a contact oil seal is also inappropriate.

[0006] To address this issue, it is conceivable to provide a labyrinth structure between the brake and encoder, but a relatively simple labyrinth structure would not provide the desired sealing effect, and a labyrinth with many bends and a complex structure would require sufficient space between the motor housing and shaft. Therefore, a motor with a sealing structure that can be installed in a small space while still providing a certain level of sealing function is desired.

[0007] One aspect of the present disclosure is a motor including a rotatable shaft having a friction plate attached thereto, a brake unit that brakes rotation of the shaft by friction with the friction plate, and a seal unit that suppresses the movement of dust from the brake unit, wherein the seal unit includes a first seal member having a first fixed portion fixed to the shaft and a first tapered portion that extends radially outward from the first fixed portion and tapered toward the friction plate, and a second seal member that has a second fixed portion fixed to a stationary portion of the motor and a second tapered portion that extends radially inward from the second fixed portion and tapered toward the friction plate, and that cooperates with the first seal member to form a labyrinth structure.

[0008] Fig. 2 is an axial cross-sectional view of a main part of a motor according to an embodiment; Fig. 3 is an axial cross-sectional view of a seal portion according to a first embodiment; Fig. 4 is a perspective view of the seal portion of Fig. 2; Fig. 5 is an axial cross-sectional view schematically showing the seal portion of Fig. 2; Fig. 6 is an axial cross-sectional view schematically showing a seal portion according to a second embodiment; and Fig. 7 is an axial cross-sectional view schematically showing a seal portion according to a third embodiment.

[0009] 1 is an axial cross-sectional view showing the schematic configuration of a main part of a motor 10 according to a preferred embodiment. The motor 10 is an electric motor, particularly a servo motor, used in machines such as robots, machine tools, injection molding machines, presses, printing machines, semiconductor manufacturing machines, and mounters. The motor 10 has a stator (not shown) and a rotor 12 configured to be rotatable relative to the stator. The rotor 12 has a shaft 16 that is rotatable about an axis 14.

[0010] The motor 10 has a detection unit (encoder in this example) 18 that detects the rotational angular position of the shaft 16, and a brake unit 20 that brakes the rotation of the shaft 16. The encoder 18 in the illustrated example is an optical encoder, and has a rotary code plate 22 that is configured to rotate integrally with the shaft 16, and an optical element 24 such as a photosensor fixedly disposed on a substrate 26 or the like so as to face the rotary code plate 22.

[0011] The brake unit 20 is, for example, an electromagnetic clutch brake, and includes a brake core 30 having a coil 28, an armature 32 configured to move axially relative to the brake core 30 by turning on / off the current to the coil 28, and a side plate 34 disposed opposite the armature 32. Meanwhile, a friction plate (clutch plate) 38 is attached to the shaft 16 via a key 36, and the friction plate 38 is disposed between the armature 32 and the side plate 34. By pressing the armature 32 against the friction plate 38 while the shaft 16 is rotating, the shaft 16 slows down or stops due to friction between the friction plate 38 and the armature 32 or the side plate 34.

[0012] The substrate 26 may be fixed to the brake core 30 by an appropriate connecting member 40, but is not limited to this. The rotor 12, encoder 18, and brake unit 20 can be housed in a casing 42 of an appropriate shape and size. The encoder 18 and brake unit 20 may have the same configuration and function as conventional ones, so detailed description thereof will be omitted hereafter.

[0013] In the motor 10, the brake unit 20 and the encoder 18 are disposed close to each other, and therefore a seal unit 44 is provided close to the brake unit 20 (more specifically, between the brake unit 20 and the encoder 18) to prevent problems such as wear powder generated by friction of the clutch plate 38 moving to the encoder 18 side (rotary code plate 22) and preventing normal detection by the optical element 24. Specific examples of the seal unit 44 will be described below.

[0014] 2 and 3 are an axial cross-sectional view and a perspective view, respectively, showing a first embodiment of the seal portion 44, and Fig. 4 is an enlarged view schematically showing the seal portion 44. The seal portion 44 has a first seal member 46 fixed to the shaft 16 and a second seal member 50 fixed to a stationary portion of the motor 10 (here, an inner surface 48 of the brake core 30), and the first seal member 46 and the second seal member 50 cooperate to form a labyrinth structure.

[0015] The first seal member 46 has a substantially annular first fixed portion 52 fixed to the outer surface of the shaft 16 by interference fitting, press fitting, or the like, and a first tapered portion 54 extending from the first fixed portion 52 in a tapered manner, inclined radially outward and toward the friction plate 38 (the opposite side of the encoder 18) (for example, inclined at an angle of 30 to 60 degrees with respect to the axis 14). On the other hand, the second seal member 50 has a substantially annular second fixed portion 56 fixed to a stationary portion of the motor 10 (here, the inner surface 48 of the brake core 30) that does not rotate with the shaft 16 by press fitting, or the like, and a second tapered portion 58 extending from the second fixed portion 56 in a tapered manner, inclined radially inward and toward the friction plate 38 (the opposite side of the encoder 18) (for example, inclined at an angle of 30 to 60 degrees with respect to the axis 14). However, the second tapered portion 58 is not parallel to the first tapered portion 54, but forms an angle of 90 degrees with respect to each other, for example, in an axial cross section.

[0016] The second seal member 50 further has a third tapered portion 60 that extends radially inward from the second tapered portion 58 and generally parallel to the first tapered portion 54, and the third tapered portion 60 cooperates with the first tapered portion 54 to form a narrow gap. In other words, the first seal member 46 and the second seal member 50 cooperate to form a labyrinth structure that makes it difficult for dust and the like to enter the encoder side.

[0017] The first fixed portion 52 and the first tapered portion 54 of the first seal member 46 cooperate to form a space 68 that tapers toward the encoder 18 (the rotary code plate 22 thereof) in an axial cross section, and this space 68 functions as a first accumulation location for collecting and accumulating dust such as wear powder from the friction plate 38, which advances in the direction of the arrow 66. Furthermore, the second fixed portion 56 and the second tapered portion 58 of the second seal member 50 cooperate to form a space 70 that tapers toward the encoder 18 (the rotary code plate 22 thereof) in an axial cross section, and this space 70 functions as a second accumulation location for collecting and accumulating dust that advances in the direction of the arrow 66 and that could not be collected in the first accumulation location 68.

[0018] In the first embodiment, the surface 55 of the first tapered portion 54 and the surface 59 of the third tapered portion 60, which faces and is generally parallel to the surface 55, cooperate to form a narrow passage, and further, the tip end face 64 of the third tapered portion 60 faces the inclined surface 62 of the third seal member 23 fixed to the shaft 16 to form the narrow passage. More specifically, the inclined surface 62 of the third seal member 23 is generally parallel to the tip end face 64 of the third tapered portion 60, and cooperates with the tip end face 64 to form a labyrinth structure. This greatly reduces the possibility that dust and the like that could not be captured even in the second accumulation location 70 will adversely affect the encoder 18.

[0019] The first seal member 46 and the second seal member 50 can be produced, for example, by sheet metal processing, more specifically, by drawing a sheet metal having a thickness of about 1 mm.

[0020] The third seal member 23 can be made by, for example, cutting out a metal material, more specifically, by cutting out aluminum. The third seal member 23 may be formed as a part of the rotary code plate 22, essentially integral with the brake-side surface of the rotary code 2, or may be a part that is fixed to the rotary code plate 22 by press-fitting or the like, and functions as an adapter for fixing the rotary code plate 22 to the shaft 16.

[0021] 5 is an enlarged view showing a seal portion 44a according to a second embodiment. In the second embodiment, only the parts that are different from the first embodiment will be described, and parts that are the same as those in the first embodiment will be given the same reference numerals and will not be described in detail.

[0022] Similar to the first embodiment, the third tapered portion 60 of the second seal member 50 cooperates with the third seal member 23a fixed to the shaft 16 to form a narrow passage, but in the second embodiment, a surface 61 of the third tapered portion 60 opposite to the surface 59 (FIG. 4) facing the first tapered portion 54 cooperates with an inclined surface 63 of the third seal member 23a to form the narrow passage. More specifically, the inclined surface 63 of the third seal member 23a is generally parallel to the surface 61 of the third tapered portion 60 and cooperates with the surface 61 to form a labyrinth structure.

[0023] The inclined surface 63 of the third seal member 23a is spaced apart from the surface of the shaft 16 and is inclined in the opposite direction to that in the first embodiment (inclined so as to move away from the shaft 16 in the axial direction toward the clutch plate 38 (FIG. 1)). As a result, in the second embodiment, the third seal member 23a cooperates with the side surface of the shaft 16 to form a third accumulation location 71, further reducing the possibility that wear debris and the like will adversely affect the optical element 24 of the encoder and the like.

[0024] 6 is an enlarged view showing a seal portion 44b according to a third embodiment. In the third embodiment, only the parts that are different from the first embodiment will be described, and parts that are the same as those in the first embodiment will be given the same reference numerals and will not be described in detail.

[0025] The third embodiment differs from the first embodiment in that the second seal member 50b does not have a third tapered portion like the second seal member 50 in the first embodiment, but other parts may be similar. However, in the third embodiment, the first seal member 46 and the second seal member 50b cooperate to form a labyrinth structure, and the third embodiment also has a first accumulation location 68 and a second accumulation location 70 that can collect wear debris and the like, so that wear debris and the like can be efficiently prevented from entering the encoder side.

[0026] Furthermore, the first seal member 46 may have a dust retaining portion 72 containing a gel-like substance, an adhesive substance, a magnetic substance, or the like in a portion defining the first accumulation location 68 so that dust, etc. once collected in the first accumulation location 68, does not escape from the first accumulation location 68. Similarly, the second seal member 50 may have a dust retaining portion 74 containing a gel-like substance, an adhesive substance, a magnetic substance, or the like in a portion defining the second accumulation location 70 so that dust, etc. once collected in the second accumulation location 70, does not escape from the second accumulation location 70. It should be noted that the dust retaining portions 72 and 74 can of course be applied to the first and second embodiments.

[0027] According to the present disclosure, a simple labyrinth structure is formed by first and second seal members having tapered portions that are inclined in different directions, thereby providing a motor with a seal portion that can be placed in a narrow space while preventing leakage of dust and other particles generated from the friction plates, thereby enabling the entire motor to be configured compactly.

[0028] Furthermore, when a motor with a brake (e.g., a servo motor) is applied to a robot, the servo motor changes direction depending on the robot's operation, and the direction of dust movement changes accordingly. However, according to the present disclosure, the movement of dust can be efficiently restricted even in such cases.

[0029] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0030] The following additional notes are provided regarding the above-described embodiment and modifications.

[0031] (Supplementary Note 1) A motor including a rotatable shaft having a friction plate attached thereto, a brake unit that brakes rotation of the shaft by friction with the friction plate, and a seal unit that suppresses movement of dust from the brake unit, wherein the seal unit includes a first seal member having a first fixed portion fixed to the shaft and a first tapered portion that extends tapered and inclined radially outward from the first fixed portion toward the friction plate, and a second seal member that has a second fixed portion fixed to a stationary portion of the motor and a second tapered portion that extends tapered and inclined radially inward from the second fixed portion toward the friction plate, and that cooperates with the first seal member to form a labyrinth structure.

[0032] (Supplementary Note 2) The motor according to Supplementary Note 1, wherein the second seal member further includes a third tapered portion located radially inward from the second tapered portion and facing the first tapered portion, the third tapered portion cooperating with the first tapered portion to form a labyrinth structure.

[0033] (Supplementary Note 3) The motor according to Supplementary Note 2, further comprising a third seal member fixed to the shaft, facing a tip end surface of the third tapered portion or a surface of the third tapered portion opposite to the surface facing the first tapered portion, and cooperating with the third tapered portion to form a labyrinth structure.

[0034] (Supplementary Note 4) The motor according to any one of Supplementary Notes 1 to 3, further comprising a detection unit that detects rotation of the shaft, and the seal unit is disposed between the brake unit and the detection unit.

[0035] (Supplementary Note 5) The motor according to Supplementary Note 3, wherein the third seal member is a part of a rotary code plate of a detector that detects rotation of the shaft, or an adapter for attaching the rotary code plate to the shaft.

[0036] (Supplementary Note 6) The motor according to any one of Supplementary Notes 1 to 3, wherein the first seal member and the second seal member are sheet metal parts.

[0037] (Supplementary Note 7) The motor according to any one of Supplementary Notes 1 to 3, wherein at least one of the first seal member and the second seal member defines a deposit location capable of collecting dust from the friction plate.

[0038] (Supplementary Note 8) The motor according to Supplementary Note 3, wherein the third seal member cooperates with a side surface of the shaft to define a collection area capable of collecting dust from the friction plate.

[0039] (Supplementary Note 9) The motor according to Supplementary Note 7 or 8, wherein the accumulation location has a dust holding portion containing a gel-like material, a sticky material, or a magnetic material.

[0040] REFERENCE SIGNS LIST 10 Motor 12 Rotor 16 Shaft 18 Encoder 20 Brake section 22, 22a, 22b Rotary code plate 23, 23a Third seal member 24 Optical element 26 Substrate 28 Coil 30 Brake core 32 Armature 34 Side plate 36 Key 38 Friction plate 42 Casing 44, 44a, 44b Seal section 46 First seal member 50 Second seal member 52 First fixing section 54 First tapered section 56 Second fixing section 58 Second tapered section 60 Third tapered section 62, 63 Inclined surface 68 First depositing location 70 Second depositing location 71 Third depositing location 72, 74 Dust holding section

Claims

1. A motor comprising a rotatable shaft to which a friction plate is attached, a brake portion that brakes the rotation of the shaft by friction with the friction plate, and a seal portion that suppresses the movement of dust from the brake portion, wherein the seal portion includes a first seal member having a first fixing portion fixed to the shaft and a first tapered portion that extends in a tapered shape inclined radially outward and toward the friction plate side from the first fixing portion, and a second seal member having a second fixing portion fixed to a stationary portion of the motor and a second tapered portion that extends in a tapered shape inclined radially inward and toward the friction plate side from the second fixing portion, and that cooperates with the first seal member to form a labyrinth structure.

2. The motor according to claim 1, wherein the second seal member further has a third tapered portion that faces radially inward from the second tapered portion and faces the first tapered portion, and that cooperates with the first tapered portion to form a labyrinth structure.

3. The motor according to claim 2, further comprising a third seal member that is fixed to the shaft and faces the tip surface of the third tapered portion or the surface of the third tapered portion on the side opposite to the surface facing the first tapered portion, and that cooperates with the third tapered portion to form a labyrinth structure.

4. The motor according to any one of claims 1 to 3, having a detection portion that detects the rotation of the shaft, and wherein the seal portion is disposed between the brake portion and the detection portion.

5. The motor according to claim 3, wherein the third seal member is a part of a rotary code plate of a detection portion that detects the rotation of the shaft, or an adapter for attaching the rotary code plate to the shaft.

6. The motor according to any one of claims 1 to 3, wherein the first seal member and the second seal member are sheet metal parts.

7. The motor according to any one of claims 1 to 3, wherein at least one of the first seal member and the second seal member defines a deposition location capable of collecting dust from the friction plate.

8. The motor according to claim 3, wherein the third seal member cooperates with the side surface of the shaft to define a deposition location capable of collecting dust from the friction plate.

9. The motor according to claim 7 or 8, wherein the deposition location has a dust holding portion containing a gel substance, an adhesive substance, or a magnetic substance.

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