Patent Description:
Industrial robots and machine tools, such as those having a pair of arms rotatably coupled to each other, include a motor unit provided at a coupling portion (joint) between the arms so as to drive the arms. The motor unit includes a motor and a speed reducer coupled to the motor. A motor torque generated as the motor rotates is decelerated by the speed reducer and output to the arms.

Such industrial robots may be placed in an environment exposed to water when installed or used outdoors. In such cases, water penetration into the speed reducer accelerates corrosion inside the speed reducer. Therefore, water is prevented from penetrating into the speed reducer. For example, a waterproof cover may be installed on the outside of the speed reducer (see, for example, <CIT>).

<CIT> discloses a waterproof structure for electric motors and speed reducers, comprising a sealed casing and a protective cover to prevent water ingress. It describes a construction that aims to enhance the durability of motors and reducers in environments exposed to moisture. <CIT> outlines a system that utilizes sealing elements between the motor or reducer and their enclosures, focusing on mitigating the risks associated with water damage. These sealing techniques aim to ensure the operational integrity of the encapsulated components.

<CIT> introduces a transmission casing designed for critical environments, such as the food industry, where cleanliness and minimal contamination risks are paramount. The innovation lies in the configuration of the casing, where fastening elements are located inside rather than on the exterior, to avoid accumulation of dirt and facilitate easier cleaning. This design choice enhances the suitability of the transmission casing for use in sensitive applications by reducing potential contamination points and simplifying maintenance procedures.

However, a conventional waterproof cover is fixed to the speed reducer positioned inside of it with, for example, a fixing bolt tightened from the outside of the cover. In this way, when the cover is fixed from the outside, a fastener such as a fixing bolt is needed that penetrates the cover in the thickness direction. The cover thus has a through hole formed therein. Therefore, water may penetrate through the through hole into the inside of the cover, making it difficult to accomplish complete waterproofness. Therefore, quality issues remained and there was room for improvement.

According to the invention, the above problems of the prior art are overcome by a waterproof structure, as specified in independent claim <NUM>. Further improvements and variations are described in the subsequent dependent claims.

The present invention provides a waterproof structure and a rotation device capable of improving the waterproof performance.

A waterproof structure according to the invention comprises the features as defined by the independent claim <NUM>.

With this configuration, the cover can be fixed by the fixing unit from the inner peripheral side of the cover to the case housing the speed reducer. In other words, the waterproof structure according to the invention has no fixing unit on the outer peripheral side of the cover, and thus is not configured such that a fixing unit such as a fixing bolt extends through the cover to fix the cover to the case. Therefore, there is no need to provide a through hole extending through the cover, and it is possible to prevent water from entering to the speed reducer side through the through hole. Accordingly, the waterproof structure can have an improved waterproof performance. This configuration allows the cover to be integrated with the speed reducer inside without being penetrated by bolts or the like, thereby establishing waterproof quality through internal fixing.

The fixing unit may be provided on at least one of the cover or the case.

The fixing unit may fix the cover to the case in the axial direction of the electric motor.

The fixing unit may include a fastening member inserted through the holding member and tightened into the case. The holding member may be configured to clamp the protruding portion together with the case as the fastening member is tightened in the axial direction.

The speed reducer may have a flange portion protruding radially outward from an outer peripheral surface of the speed reducer. The flange portion may be located between the case and the holding member in the axial direction. The flange portion may have a through hole extending in the axial direction. The fastening member may be inserted through the through hole of the flange portion interposed between the holding member and the case and may be tightened into the case.

The holding member may be integrally fixed to an outer peripheral surface of the case in a radial direction.

The holding member may be integrally fixed to an outer peripheral surface of the speed reducer.

The holding member may be an annular plate extending over an entire circumference around a motor shaft of the electric motor.

Water stop members may be provided on both sides of the cover in the axial direction, and the water stop members may be configured to stop water between the cover and an outer peripheral surface of the case.

The fixing unit may include a fastening member inserted through the holding member and tightened into the case. The holding member may be an annular plate extending over an entire circumference around a motor shaft of the electric motor, and the holding member may be configured to clamp the protruding portion of the cover together with the case as the fastening member is tightened in the axial direction. Water stop members may be provided on both sides of the cover in the axial direction, and the water stop members may be configured to stop water between the cover and an outer peripheral surface of the case.

This configuration simplifies the fixing unit. The waterproof structure can be easily assembled by, for example, providing the fixing unit beforehand on at least one of the cover or the case. In the waterproof structure for a speed reducer according to this preferred aspect, the holding member can be used to fix the cover to the case so as to prevent the cover from moving in the axial direction. In the waterproof structure for a speed reducer according to this preferred aspect, the holding member is fixed as the fastening member is tightened. The fixed holding member can clamp the protruding portion together with the case, and thus the cover can be fixed to the case so as to prevent the protruding portion from moving in the axial direction. In this preferred aspect, the cover can be easily fixed to the case only by tightening the fastening member, improving the work efficiency in assembling the waterproof structure. In the waterproof structure for a speed reducer according to this preferred aspect, for example, the cover, the speed reducer, and the case can be fixed simultaneously by inserting the fastening member through a through hole in the speed reducer and tightening the fastening member into the case. Therefore, the time and labor required for assembling the waterproof structure can be reduced, resulting in an improved work efficiency. In the waterproof structure for a speed reducer according to this preferred aspect, one holding member can hold the cover against the case with a balanced and uniform force over the entire circumference. Therefore, it is possible to prevent the cover from being displaced in the axial direction and prevent the water-stopping performance from being degraded. In the waterproof structure for a speed reducer according to this preferred aspect, it is possible to ensure the water-stopping performance between the cover and the case at positions on the cover on both sides of the fixing unit in the axial direction.

A rotation device according to the invention comprises: a device body; a rotating body having a working head; an electric motor provided in the device body, the electric motor being configured to produce a driving force to rotate the rotating body; and the waterproof structure for a speed reducer as described above.

With this configuration, the waterproof structure can be installed on the rotation device having the rotating body configured to be rotated by the rotational driving force transmitted from the electric motor and the speed reducer.

The waterproof structure and the rotation device described above can improve the waterproof performance.

The embodiments of the present invention will be hereinafter described with reference to the drawings. In the following embodiments and modifications, like elements will be denoted by the same reference signs and redundant descriptions will be partly omitted.

<FIG> is a side view showing an industrial robot <NUM> including a speed reducer <NUM> in a driving unit, and the speed reducer <NUM> is configured to be installed on a motor with a speed reducer. The industrial robot <NUM> (rotation device) according to the present embodiment is an industrial robot used, for example, for feeding, shipping, transporting, and assembling parts of precision equipment and the like. The industrial robot <NUM> has a pedestal <NUM> (device body), a first arm <NUM> (rotating body), a second arm <NUM> (rotating body), a working head <NUM>, and an end-effector <NUM>.

The first arm <NUM>, which is rotatable around an axis O1, is coupled with the pedestal <NUM>. The second arm <NUM>, which is rotatable around an axis parallel to the axis O1, is coupled with the first arm <NUM>. The working head <NUM> is provided at the distal end of the second arm <NUM> and coupled with the end-effector <NUM>. The pedestal <NUM> contains an electric motor <NUM> such as a servomotor, and the speed reducer <NUM> for reducing the speed of the rotations of the electric motor <NUM>. The first arm <NUM> can be rotated by the driving force from the motor <NUM>. As shown in <FIG>, an input shaft <NUM> (described later) of the speed reducer <NUM> is coupled with the rotating shaft (a motor shaft <NUM>) of the electric motor <NUM>. An output-side case <NUM> of the speed reducer <NUM> is coupled with the first arm <NUM>. When the driving force from the electric motor <NUM> is transmitted to the first arm <NUM> through the speed reducer <NUM>, the first arm <NUM> rotates within a horizontal plane around the axis O1.

As shown in <FIG>, the speed reducer <NUM> is provided in the above-described industrial robot <NUM> at a coupling portion (joint) of the first arm <NUM> rotatably coupled to the pedestal <NUM>. The speed reducer <NUM> decelerates at a predetermined reduction ratio a motor torque inputted thereto from the electric motor <NUM> serving as a drive source and outputs the decelerated torque to the output-side case <NUM>. In other words, the speed reducer <NUM> is configured to change the number of rotations at a predetermined ratio and transmit a resulting driving force between the drive source and a movable part such as an arm.

In the following description of the embodiments, the direction along the axis O1 of the electric motor <NUM> of the speed reducer <NUM> is hereunder simply referred to as the axial direction, and a direction orthogonal to the axis O1 as viewed in the axial direction is referred to as a radial direction, and a circumferential direction about the axis O1 is simply referred to as a circumferential direction. Furthermore, with respect to the axial direction, the term "the axially inner side" may refer to the inwardly facing side of an object, and the term "the axially outer side" may refer to the opposite side of the object. With respect to the axial direction, the term "input side X1" refers to the side of the speed reducer <NUM> connected to the drive source, and the term "output side X2" refers to the side of the speed reducer <NUM> connected to the mechanical part such as an arm receiving the output from the speed reducer <NUM>.

As shown in <FIG>, the speed reducer <NUM> includes a reduction unit (not shown) having planetary gears or the like between the motor shaft <NUM> of the electric motor <NUM> and the first arm <NUM>. In the following description, portions of the speed reducer <NUM> are referred to as follows. With respect to the direction of the axis O1 (the axial direction) extending through the central axis of the motor shaft <NUM>, the side on the electric motor <NUM> is the input side X1 (the right side in the drawing), and the side opposite thereto is the output side X2 (the left side in the drawing). As viewed from the direction of the axis O1, a direction toward the outer peripheral side of the speed reducer <NUM> in a radial direction orthogonal to the axis O1 is referred to as a radially outward direction, and a direction toward the axis O1 in a radial direction orthogonal to the axis O1 is referred to as a radially inward direction.

Next, the waterproof structure <NUM> for the speed reducer <NUM> according to the present embodiment will be described in detail with reference to <FIG> and <FIG>. <FIG> is a sectional view of a driving unit including the electric motor <NUM> and the speed reducer <NUM>. <FIG> is an enlarged view of the region F1 of <FIG>. In the waterproof structure <NUM>, the entirety of the speed reducer <NUM> is covered in a liquid-tight manner to improve waterproof performance.

As shown in <FIG>, the waterproof structure <NUM> includes: the speed reducer <NUM> configured to decelerate the rotational driving force from the electric motor <NUM> and transmits the decelerated rotational driving force to a rotationally driven portion (such as the first arm <NUM> shown in <FIG>); a case (a motor flange <NUM> described later) that houses the motor shaft <NUM> of the electric motor <NUM> and the speed reducer <NUM>; and a cover <NUM> that externally covers the speed reducer <NUM> in a liquid-tight manner.

The electric motor <NUM> includes the motor shaft <NUM>, a motor body <NUM>, a motor case <NUM> (a case) retaining the motor body <NUM>, and a motor flange <NUM> fixed to one end 22a of the motor case <NUM> positioned on the output side X2. The motor shaft <NUM> is located at the center of the motor body <NUM> and extends in the axial direction. The distal end portion of the motor shaft <NUM> positioned on the output side X2 projects into the speed reducer <NUM> via the input shaft <NUM>. The electric motor <NUM> is mounted to the speed reducer <NUM> via the motor flange <NUM>. The electric motor <NUM> may be selected from various motors that drive on electricity, such as what is called brushed motors and brushless motors.

The motor case <NUM> has a tubular shape and houses the motor body <NUM>. The motor case <NUM> has a case fixing portion <NUM> positioned on the inner peripheral surface of the end portion of the motor case <NUM> on the output side X2. The case fixing portion <NUM> extends over the entire circumference and protrudes inward in the radial direction. The case fixing portion <NUM> is fixed to an input-side end surface 23b of the motor flange <NUM> with second fixing bolts <NUM>. The second fixing bolts <NUM> are inserted through the case fixing portion <NUM> from the input side X1 and tightened into the input-side end surface 23b of the motor flange <NUM>.

The motor flange <NUM> has an annular shape. The central portion of the motor flange <NUM> rotatably supports the motor shaft <NUM>. The motor flange <NUM> is fixed to the one end 22a of the tubular motor case <NUM> with the second fixing bolts <NUM>. The cover <NUM> is fitted on and fixed to the outer peripheral side of the motor flange <NUM>.

The motor flange <NUM> is integrally formed of a flange plate <NUM> and a flange tube <NUM> located on the output side X2 of the flange plate <NUM>. The flange plate <NUM> allows the motor shaft <NUM> and the input shaft <NUM> to be inserted therein. Furthermore, the flange plate <NUM> has a central opening portion <NUM> that rotatably supports the input shaft <NUM> via an annular seal member <NUM>. As shown in <FIG>, the outer peripheral surface 23a of the motor flange <NUM> has a first stepped surface 23d facing the output side X2. The outer peripheral surface 23a has a reduced diameter on the output side X2 of the first stepped surface 23d.

As shown in <FIG>, the flange tube <NUM> extends from the periphery of the flange plate <NUM> toward the output side X2. As shown in <FIG>, the output-side end surface 23c of the flange tube <NUM>, which is located on the output side X2, is at a position where it contacts with the input-side peripheral edge 10b of the speed reducer <NUM> to support the speed reducer <NUM>. The output-side end surface 23c of the flange tube <NUM> has internally threaded portions 23f to which first fixing bolts <NUM> (described later) are screwed. The internally threaded portions 23f are arranged at intervals in the circumferential direction of the flange tube <NUM>.

The distal end portion (the output-side end surface 23c) of the flange tube <NUM> contacts with the input-side peripheral edge 10b of the speed reducer <NUM> to support the speed reducer <NUM>. Furthermore, the flange tube <NUM> has a locking portion 26a positioned on the periphery of the output-side end surface 23c of the flange tube <NUM>. The locking portion 26a protrudes toward the output side X2. The locking portion 26a supports flange portions <NUM> (described later) of the speed reducer <NUM> at the outer peripheral side.

In the outer peripheral surface 23a of the motor flange <NUM>, there are provided a pair of first water stop members <NUM> having an annular shape and configured to stop water between the outer peripheral surface 23a and the inner peripheral surface 5a of the cover <NUM> on the input side X1. The first water stop members <NUM> are arranged at an interval in the axial direction. The first water stop members <NUM> are, for example, O-rings. The first water stop members <NUM> also serve to stop water between the input-side end surface 23b of the motor flange <NUM> and the end surface (the one end 22a) of the motor case <NUM> on the output side X2.

As shown in <FIG>, the speed reducer <NUM> includes a reduction unit (not shown) consisting of a multi-stage planetary mechanism, for example, that decelerates the rotational driving force of the electric motor <NUM> from the input stage side to the output stage side and transmits the decelerated rotational driving force to the rotationally driven portion. The speed reducer <NUM> will not be described in detail for the present embodiment.

The speed reducer <NUM> is fixed to an output-side end surface 23c of the motor flange <NUM> of the electric motor <NUM> with fixing bolts (not shown).

In this embodiment, the output-side case <NUM> provided on the output side X2 of the speed reducer <NUM> is connected to the first arm <NUM>. Thus, the rotational driving force of the electric motor <NUM> is transmitted to the input shaft <NUM>, the rotational driving force decelerated by the speed reducer <NUM> is transmitted to the output-side case <NUM> and then to the first arm <NUM> that is fixed to the output-side case <NUM>. In the first arm <NUM>, the decelerated rotational driving force can be taken out as an output.

In the outer peripheral surface 13a of the output-side case <NUM>, there is provided a second water stop member <NUM> having an annular shape and configured to stop water between the outer peripheral surface 13a and the inner peripheral surface 5a of the cover <NUM> on the output side X2. The second water stop member <NUM> is, for example, an X-ring.

The speed reducer <NUM> has flange portions <NUM> protruding radially outward from the outer peripheral surface 10a of the speed reducer <NUM> on the input side X1. The flange portions <NUM> is located between the motor flange <NUM> and the holding plate <NUM> (described later) in the axial direction. The flange portions <NUM> are arranged at intervals in the circumferential direction on the outer peripheral surface 10a of the speed reducer <NUM>. Each of the flange portions <NUM> has a through hole 14a extending in the axial direction (see <FIG>). The first fixing bolt (fastening member) <NUM> (described later) is inserted through the through hole 14a. The flange portion <NUM> has such a circumferential length that at least one through hole 14a (described later) can extend through the flange portion <NUM> in the axial direction.

As shown in <FIG>, the input-side end 14b of each of the flange portions <NUM>, which is located on the input side X1, is fixed so as to be in contact with the output-side end surface 23c of the flange tube <NUM> of the motor flange <NUM>. The output-side end surface 14c of each of the flange portions <NUM>, which is located on the output side X2, is fixed by the first fixing bolt <NUM> so as to be in contact with the holding plate <NUM> (described later).

As shown in <FIG>, the cover <NUM> has a cylindrical shape and externally covers and houses the speed reducer <NUM> and the motor shaft <NUM> in a liquid-tight manner. The cover <NUM> is made of, for example, a stainless steel or the like. On the radially inner side of the inner peripheral surface 5a of the cover <NUM>, there are provided the holding plate <NUM> (holding member) and the first fixing bolts <NUM> serving as a fixing unit for fixing the cover <NUM> to the motor flange <NUM>. The cover <NUM> has a protruding portion <NUM> (fixing unit) protruding radially inward and extending over at least a part of the circumference of the inner peripheral surface 5a.

As shown in <FIG>, the protruding portion <NUM> includes an input-side protruding portion 51A located on the input side X1 and an output-side protruding portion 51B located on the output side X2. The input-side protruding portion 51A is located on the outer peripheral side of the motor flange <NUM> when the cover <NUM> is fixed to the motor flange <NUM>. The output-side protruding portion 51B is located on the outer peripheral side of the flange portions <NUM> of the speed reducer <NUM> when the cover <NUM> is fixed to the motor flange <NUM>. The output-side protruding portion 51B is located between the motor flange <NUM> and the holding plate <NUM> in the axial direction. The input-side protruding portion 51A has a first stepped surface 51a which faces the input side X1. The first stepped surface 51a is in contact with the first stepped surface 23d formed on the outer peripheral surface 23a of the motor flange <NUM>.

The holding plate <NUM> clamps the protruding portion <NUM> together with the motor flange <NUM> in the axial direction of the electric motor <NUM>. The holding plate <NUM> is an annular plate extending over the entire circumference, and the front and back surfaces thereof face in the axial direction. The holding plate <NUM> is fixed in the axial direction toward the motor flange <NUM> by tightening the first fixing bolts <NUM> from the output side X2. The holding plate <NUM> has bolt holes (not shown) arranged at predetermined intervals along the circumferential direction. The bolt holes are located at the positions corresponding to the through holes 14a in the flange portions <NUM>.

The first fixing bolts <NUM> are inserted through the through holes 14a in the flange portions <NUM> interposed between the holding plate <NUM> and the motor flange <NUM>, and are tightened and fixed to the internally threaded portions 23f formed in the output-side end surface 23c of the motor flange <NUM>. In other words, the first fixing bolts <NUM> fix the cover <NUM> to the motor flange <NUM> in the axial direction.

The first water stop members <NUM> stop water between the inner peripheral surface 5a of the input-side end portion 5b of the cover <NUM> and the outer peripheral surface 23a of the motor flange <NUM>. The second water stop member <NUM> stops water between the inner peripheral surface 5a of the output-side end portion 5c of the cover <NUM> and the outer peripheral surface 13a of the output-side case <NUM>.

Next, the process of assembling the waterproof structure <NUM> is described based on <FIG> and <FIG>. The first step is as follows. After the speed reducer <NUM> is fixed to the motor flange <NUM> of the electric motor <NUM>, and the output-side case <NUM> is detached from the speed reducer <NUM>, the cover <NUM> is fitted onto the outer peripheral side of the speed reducer <NUM> and the motor flange <NUM> from the output side X2. At this time, the first stepped surface 51a of the input-side protruding portion 51A contacts with the first stepped surface 23d formed on the outer peripheral surface 23a of the motor flange <NUM>. Thus, the cover <NUM> is prevented from moving to the input side X1 along the axial direction. In other words, the cover <NUM> is fixed in the position in which the first stepped surface 51a and the first stepped surface 23d are in contact with each other.

Next, the holding plate <NUM> is advanced from the output side X2 into the gap S between the outer peripheral surface 10a of the speed reducer <NUM> and the inner peripheral surface 5a of the cover <NUM>, and the holding plate <NUM> is placed so that it contacts with the output-side end surfaces 14c of the flange portions <NUM>. Subsequently, the first fixing bolts <NUM> are advanced into the gap S from the output side X2, inserted through the through holes (not shown) in the holding plate <NUM> and the through holes 14a in the flange portions <NUM>, and tightened to the internally threaded portions 23f of the motor flange <NUM> for fastening. By tightening the first fixing bolts <NUM>, the holding plate <NUM> is fixed to the motor flange <NUM> together with the flange portions <NUM> (the speed reducer <NUM>). Thus, the protruding portion <NUM> of the cover <NUM> is clamped and fixed in the axial direction between the holding plate <NUM> and the motor flange <NUM>. In other words, the cover <NUM> is prevented from moving in the axial direction. The output-side case <NUM> with the second water stop member <NUM> is then fixed to the output side X2 of the speed reducer <NUM>. Thus, the assembling of the waterproof structure <NUM> is completed.

As described above, the waterproof structure <NUM> for the speed reducer <NUM> according to the embodiment includes: the speed reducer <NUM> configured to decelerate the rotational driving force from the electric motor <NUM> and transmits the decelerated rotational driving force to a rotationally driven portion; the motor flange <NUM> that houses the motor shaft <NUM> of the electric motor <NUM> and the speed reducer <NUM>; and a cover <NUM> that externally covers the speed reducer <NUM> in a liquid-tight manner. The fixing unit (the holding plate <NUM>, the protruding portion <NUM>, and the first fixing bolts <NUM>) for fixing the cover <NUM> to the motor flange <NUM> is provided on the inner peripheral side of the cover <NUM>. Therefore, in the waterproof structure <NUM> for the speed reducer <NUM> according to the embodiment, the cover <NUM> can be fixed by the fixing unit on the inner peripheral side of the cover <NUM> to the motor flange <NUM> that houses the speed reducer <NUM>. Therefore, there is no need to provide a fixing structure on the outer peripheral side of the cover <NUM>, and no fixing unit such as fixing bolts extends through the cover <NUM> for fixing to the motor flange <NUM>. Therefore, there is no need to provide through holes extending through the cover <NUM>. Accordingly, water does not enter through the through holes to the speed reducer <NUM> side, thus the waterproof structure <NUM> has an improved waterproof performance. This configuration allows the cover <NUM> to be integrated with the speed reducer <NUM> inside without being penetrated by bolts or the like, thereby establishing waterproof quality through internal fixing.

In the waterproof structure <NUM> for the speed reducer <NUM> according to the embodiment, the fixing unit is provided on at least one of the cover <NUM> or the motor flange <NUM>. This allows for a simple configuration of the fixing unit. In addition, the waterproof structure <NUM> can be easily assembled by, for example, providing the fixing unit beforehand on at least one of the cover <NUM> or the motor flange <NUM>.

Furthermore, in the waterproof structure <NUM> for the speed reducer <NUM> according to the embodiment, the fixing unit fixes the cover <NUM> to the motor flange <NUM> in the axial direction. Thus, the cover <NUM> can be fixed to the motor flange <NUM> so as to be prevented from moving in the axial direction.

In the waterproof structure <NUM> for the speed reducer according to the embodiment, the fixing unit includes: a protruding portion <NUM> protruding radially inward from the inner peripheral surface 5a of the cover <NUM>; and a holding plate <NUM> that clamps the protruding portion <NUM> together with the motor flange <NUM> in the axial direction of the electric motor <NUM>. Thus, with the holding plate <NUM>, the cover <NUM> can be fixed to the motor flange <NUM> so as to be prevented from moving in the axial direction.

Furthermore, in the waterproof structure <NUM> for the speed reducer according to the embodiment, the fixing unit includes the first fixing bolts <NUM> inserted through the holding plate <NUM> and tightened into the motor flange <NUM>. The first fixing bolts <NUM> are tightened in the axial direction, such that the holding plate <NUM> clamps the protruding portion <NUM> of the cover <NUM> together with the motor flange <NUM>. Therefore, the holding plate <NUM> can be fixed by tightening the first fixing bolts <NUM>. The fixed holding plate <NUM> can clamp the protruding portion <NUM> together with the motor flange <NUM>, and thus the cover <NUM> can be fixed to the motor flange <NUM> so as to prevent the protruding portion <NUM> from moving in the axial direction. Therefore, in this embodiment, the cover <NUM> can be easily fixed to the motor flange <NUM> only by tightening the first fixing bolts <NUM>, improving the work efficiency in assembling the waterproof structure <NUM>.

In the waterproof structure <NUM> for the speed reducer according to the embodiment, the speed reducer <NUM> includes the flange portions <NUM> located between the motor flange <NUM> and the holding plate <NUM> in the axial direction and protruding radially outward from the outer peripheral surface 10a of the speed reducer <NUM>. Each of the flange portions <NUM> has a through hole 14a extending in the axial direction. The first fixing bolts <NUM> are inserted through the through holes 14a in the flange portions <NUM> interposed between the holding plate <NUM> and the motor flange <NUM>, and are tightened into the motor flange <NUM>. With this configuration, the first fixing bolts <NUM> are inserted through the through holes 14a in the flange portions <NUM> of the speed reducer <NUM> and are tightened into the motor flange <NUM>, making it possible to fix the cover <NUM>, the speed reducer <NUM>, and the motor flange <NUM> simultaneously. Therefore, the time and labor required for assembling the waterproof structure <NUM> can be reduced, resulting in an improved work efficiency.

In the waterproof structure <NUM> for the speed reducer according to the embodiment, the holding plate <NUM> is an annular plate that extends over the entire circumference around the motor shaft of the electric motor <NUM>. This configuration makes it possible that one holding plate <NUM> holds the cover <NUM> against the motor flange <NUM> with a balanced and uniform force over the entire circumference. Therefore, it is possible to prevent the cover <NUM> from being displaced in the axial direction and prevent the water-stopping performance from being degraded.

The waterproof structure <NUM> for the speed reducer according to the embodiment includes the water stop members <NUM>, <NUM> provided on both sides of the cover <NUM> in the axial direction and configured to stop water between the cover <NUM> and the outer peripheral surface 23a of the motor flange <NUM> and between the cover <NUM> and the outer peripheral surface 13a of the output-side case <NUM>. This configuration ensures the water-stopping performance between the cover <NUM> and the motor flange <NUM> and between the cover <NUM> and the output-side case <NUM> at positions on the cover <NUM> on both sides of the fixing unit in the axial direction.

In addition, the rotation device according to the embodiment includes: the pedestal <NUM>; the second arm <NUM> having the working head <NUM>; the electric motor <NUM> provided in the pedestal <NUM> and configured to provide a driving force to rotate the first arm <NUM>, the speed reducer <NUM> configured to decelerate the rotational driving force of the electric motor <NUM> and transmit the decelerated rotational driving force to the rotationally driven portion; the motor flange <NUM> that houses the speed reducer <NUM>; and the cover <NUM> that externally covers the speed reducer <NUM> in a liquid-tight manner. The fixing unit for fixing the cover <NUM> to the motor flange <NUM> is provided on the inner peripheral side of the cover <NUM>. Therefore, the waterproof structure <NUM> for the speed reducer <NUM> can be installed on the rotation device having the first arm <NUM> as the rotating body configured to be rotated by the rotational driving force transmitted from the electric motor <NUM> and the speed reducer <NUM>.

The present invention is not limited to the above-described embodiments, and the embodiments can be modified in a variety of designs.

For example, in the above embodiment, the fixing unit including the holding plate <NUM> (holding member) and the first fixing bolts <NUM> are provided on the motor flange <NUM> (case) via the flange portions <NUM> of the speed reducer <NUM> on the radially inner side of the cover <NUM>, but this configuration is not limitative. For example, the fixing unit may be provided on the cover <NUM>. Thus, the fixing unit is provided on at least one of the cover <NUM> or the case.

The holding member is not necessarily annular in the circumferential direction and plate-shaped like the holding plate <NUM> in the embodiment. For example, the holding member is not necessarily integrated over the entire circumference, but may be constituted by a plurality of parts arranged in the circumferential direction. The holding member may be integrally fixed to the outer peripheral surface 10a of the speed reducer <NUM>. In other words, the holding member may be integrally provided on the output-side end surfaces 14c on the output side X2 of the flange portions <NUM> of the speed reducer <NUM> according to the embodiment, or the flange portions <NUM> may be configured to serve as a holding member.

Furthermore, it is also possible that the holding member is integrally fixed to the outer peripheral surface of the case. For example, the holding member may be fixed to the output-side end surface 23c of the motor flange <NUM>.

A modification of the fixing unit may include: for example, a protruding portion protruding radially inward from the inner peripheral surface 5a of the cover <NUM> and having through holes that extend through the protruding portion in the axial direction of the electric motor <NUM>; and fastening members constituted by fixing bolts inserted through the through holes and tightened into the case. Thus, the protruding portion and the fastening members constituting the fixing unit are provided on the cover <NUM> side. In this case, the protruding portion of the cover <NUM> can be fixed directly to the case.

In the embodiment, the first fixing bolts <NUM> are used as the fastening members, but the fastening members are not limited to bolts, but may be screws or any other fixing members.

Claim 1:
A waterproof structure (<NUM>) comprising:
an electric motor (<NUM>);
a speed reducer (<NUM>) for decelerating a rotational driving force of the electric motor (<NUM>) and transmitting the decelerated rotational driving force to a rotationally driven portion (<NUM>);
a case (<NUM>, <NUM>) housing the speed reducer (<NUM>);
a cover (<NUM>) externally covering the speed reducer (<NUM>) in a liquid-tight manner; and
a fixing unit (<NUM>, <NUM>, <NUM>) provided on an inner peripheral side of the cover (<NUM>) to fix the cover (<NUM>) to the case (<NUM>),
characterized in that
the fixing unit (<NUM>, <NUM>, <NUM>) includes:
a protruding portion (<NUM>) protruding radially inward from an inner peripheral surface (5a) of the cover (<NUM>); and
a holding member (<NUM>) clamping the protruding portion (<NUM>) together with the case (<NUM>) in an axial direction of the electric motor (<NUM>).