Air-cooled electric motor

Abstract

The air-cooled electric motor according to the present disclosure has: an electric motor body in which a through-hole is provided in the rotary shaft; a supply part that supplies a fluid to the through-hole; a cylindrical member that surrounds the supply part; and a cooling fan that is provided opposite the electric motor body with respect to the cylindrical member. The cylindrical member is provided with a plurality of passages through which cooling air flows toward the cooling fan. The plurality of passages surround the supply part, are positioned isolated from the supply part, and are disposed at intervals with each other so as to form a window part capable of visually checking the supply part from the outside. A wall part is disposed between the supply part and the cooling fan side so as to prevent suction of gas around the supply part by the cooling fan. The plurality of passage parts are in communication with each other so that cooling air flowing through the plurality of isolated passage parts joins on the cooling fan side of the wall part. The wall part is provided with at least one ventilation hole that is in communication with the supply part.

Description

Air-cooled Electric Motor

[0001] The present disclosure relates to an air-cooled electric motor.

[0002] An air cooling method is commonly used for cooling an electric motor main body. As one type of air cooling method, in a case where a supply unit that supplies fluid to a through hole provided in a rotating shaft is provided, there is an air cooling method that includes a cylindrical distance block surrounding the supply unit, and allows cooling air to flow through a plurality of ventilation paths provided in the distance block toward a cooling fan provided on a side opposite to the electric motor main body (for example, Patent Document 1). A window is formed in the distance block so that the supply unit can be visually observed from the outside. Further, the plurality of ventilation paths provided in the distance block surround the supply unit, are located at positions spaced apart from the supply unit, and are arranged at intervals from each other.

[0003] Japanese Unexamined Patent Application Publication No. 2004-088850

[0004] There is a minute gap between the internal space of the distance block with a window and the ventilation path. Therefore, depending on the ventilation condition of the cooling fan, air flows through the minute gap, which may cause a whistling noise. Since the ventilation performance of the cooling fan changes depending on the used voltage, power supply frequency, or variations in the performance of the cooling fan itself, it is difficult to reduce the whistling noise according to the ventilation condition. A mechanism capable of reducing whistling noise generated by an electric motor is desired in machines equipped with the electric motor, manufacturing sites of the machines, and usage sites of the machines.

[0005] The air-cooled electric motor according to the present disclosure solves the above problem by providing a ventilation hole in a wall on the cooling fan side of the internal space of the distance block with a window, adjusting the ventilation performance of the cooling fan, and reducing the air volume passing through the minute gap on the electric motor side.

[0006] Furthermore, one aspect of the present disclosure is an air-cooled electric motor comprising: an electric motor body having a through hole in the rotating shaft; a supply unit for supplying fluid to the through hole; a cylindrical member surrounding the supply unit; and a cooling fan provided on the side of the cylindrical member opposite to the electric motor body, wherein the cylindrical member is provided with a plurality of passages for circulating cooling air toward the cooling fan, the plurality of passages are spaced apart from each other so as to surround the supply unit and be isolated from the supply unit, and form a window so as to allow the supply unit to be viewed from the outside, a wall is provided between the supply unit and the cooling fan so as to prevent the cooling fan from drawing in air around the supply unit, the plurality of passages are connected so as to converge on the cooling fan side of the wall so as to allow the cooling air that has circulated through the isolated plurality of passages to converge, and at least one ventilation hole communicating with the supply unit is provided in the wall.

[0007] This is a schematic external view of an air-cooled electric motor according to a first embodiment of the present disclosure. This is a schematic cross-sectional view of an air-cooled electric motor according to a first embodiment of the present disclosure. This is an enlarged cross-sectional view of the joint between the electric motor body and the cylindrical member. This is a schematic diagram illustrating a structure in which the ventilable area of ​​a ventilation hole is adjusted with a sliding lid. This is a schematic diagram illustrating a structure in which the ventilable area of ​​a ventilation hole is adjusted with a rotatable lid. This is a schematic diagram illustrating a structure in which the ventilable area of ​​a ventilation hole is adjusted with a removable lid. This is a schematic diagram illustrating a structure in which the ventilable area of ​​a ventilation hole is adjusted with a blocking member.

[0008] Embodiments of this disclosure will be described below with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplication of these components may be omitted.

[0009] In this application, "based on XX" means "based on at least XX," and includes cases where it is based on another element in addition to XX. Furthermore, "based on XX" is not limited to cases where XX is used directly, but also includes cases where it is based on something that has been calculated or processed. "XX" is any element (for example, any information).

[0010] [First Embodiment] Figure 1 is an external view showing the main parts of an air-cooled electric motor 100 according to the first embodiment. The electric motor body 1 shown in Figure 1 includes a rotating shaft 2 provided with a through hole 10 (not shown). A rotary coupling 3 is attached to the rear side of the electric motor body 1 (upper side in Figure 1), forming a supply unit that supplies fluid (liquid or gas, mist, etc.) to the through hole 10 provided in the rotating shaft 2. A hose 11 is connected to the rotary coupling 3, and fluid is supplied to the rotary coupling 3 through this hose (fluid supply pipe) 11. The fluid supplied from the rotary coupling 3 to the through hole 10 is blown onto the machining area of ​​the workpiece through a spindle or tool (not shown) with a through hole attached to the end of the rotating shaft (lower side in Figure 1). This fluid serves to cool, lubricate, and discharge chips from the machining area.

[0011] The space surrounding the rotary coupling 3 is enclosed by a cylindrical member 20 that is detachably attached to the rear end of the motor body 1. This cylindrical member 20 is also called a distance block. The cylindrical member 20 is provided with a window 5, which is used for maintenance of the rotary coupling 3 and for attaching and detaching the hose 11, as well as for draining any fluid that leaks out in the event of a malfunction of the rotary coupling 3, preventing the leaked fluid from entering the inside of the motor body 1. A cooling fan 4 is attached to the side of the cylindrical member 20 opposite to the motor body 1.

[0012] Figure 2 is a cross-sectional view showing the main parts of the air-cooled electric motor 100 according to the first embodiment. Note that the rotary coupling 3 is omitted in Figure 2. Several cooling air passages 13 are provided at appropriate locations on the electric motor body 1 to dissipate the heat generated by the electric motor itself. The cooling air passages 13 open outwards at appropriate locations on the front of the electric motor body 1 to allow outside air to be taken in (intake). In addition, the cylindrical member 20 is provided with a plurality of passage sections 41, which connect the cooling fan 4 to the cooling air passages 13 provided on the electric motor body 1. The passage sections 41 are provided on the outer wall of the cylindrical member 20 and are isolated from the rotary coupling 3. Also, in order to provide the window section 5, it is desirable that the passage sections 41 be spaced apart. As a result, as shown by the line arrows in Figure 2, the flow of cooling air is maintained from the cooling air passages 13 of the electric motor body 1 → passage sections 41 of the cylindrical member 20 → cooling fan 4.

[0013] A wall portion 45 is provided on the side of the cylindrical member 20 to which the cooling fan 4 is attached. The wall portion 45 divides the space around the rotary joint 3, which is surrounded by the cylindrical member 20, from the space on the cooling fan 4 side. That is, the wall portion 45 is positioned between the rotary joint 3 and the cooling fan 4 so as to obstruct the intake of air around the rotary joint 3 by the cooling fan 4. The wall portion 45, the outer wall of the cylindrical member 20, and the cooling fan 4 form an internal space, in which the cooling air that has flowed through multiple isolated passage portions 41 converges. By forming this internal space, the intake of cooling air from the passage portions 41 is facilitated.

[0014] The wall portion 45 of the cylindrical member 20 is provided with at least one ventilation hole 47. The ventilation hole 47 is provided to draw in air from the space surrounded by the cylindrical member 20 to which the rotary joint 3 is attached. By providing this ventilation hole 47, when the cooling fan 4 rotates, a flow of cooling air is created from the passage portion 41 of the cylindrical member 20, and air is also drawn in from the ventilation hole 47. The area of ​​the ventilation hole 47 should be large enough to create an airflow in the space around the rotary joint 3 by the air drawn in from the ventilation hole 47.

[0015] The role of the ventilation holes 47 will be explained using Figure 3. Figure 3 is an enlarged cross-sectional view of the area within the dotted line frame in Figure 2. The cylindrical member 20 is fixed to the motor body 1, for example, with bolts. At this time, due to issues such as the precision of the member, a gap 61 may be created between the motor body 1 and the cylindrical member 20. When this gap 61 is present, when cooling air flows from the cooling air passage 13 of the motor body 1 to the passage portion 41 of the cylindrical member 20, a gas flow 63 is simultaneously generated from the gap 61. This is the cause of the whistling noise. The applicant has discovered that this whistling noise can be reduced by providing ventilation holes 47 in the wall portion 45 of the cylindrical member 20. There are no particular restrictions on where the ventilation holes 47 are located on the wall portion 45. However, it is more effective to place them at the position where the intake performance is highest due to the cooling fan 4. For example, if the cooling fan 4 is composed of a single centrifugal fan, it is known that the intake performance is higher the closer the ventilation holes are to the center of the centrifugal fan. In such cases, the ventilation holes 47 should be provided near the center of the fan. In other cases as well, the ventilation holes 47 should be provided in an appropriate location considering the structure of the cooling fan 4. The appropriate area of ​​the ventilation holes 47 will vary depending on the ventilation performance of the cooling fan 4. Furthermore, if the area of ​​the ventilation holes 47 is made too large, the flow of cooling air in the passage section 41 will be obstructed, and the cooling performance of the motor body 1 will decrease. For this reason, it is advisable to conduct experiments in advance to confirm the appropriate size of the ventilation holes 47, taking into account the balance between the decrease in the cooling performance of the motor body 1 and the reduction of whistling noise.

[0016] The air-cooled electric motor 100 according to this embodiment, having the above configuration, can be easily made quieter by adjusting the size of the ventilation holes 47 according to the ventilation performance of the cooling fan 4. Since these ventilation holes 47 are provided in the wall portion 45 of the cylindrical member 20 on the cooling fan 4 side, they can be adjusted as needed simply by removing the fan, and since there is no need to remove the cylindrical member 20 and the hose 11, maintainability is also ensured.

[0017] [Second Embodiment] Below, an air-cooled electric motor 100 according to the second embodiment of the present disclosure will be described with reference to Figures 4 to 7. The air-cooled electric motor 100 according to this embodiment is equipped with means for adjusting the area of ​​the ventilation holes 47.

[0018] Figure 4 is a schematic diagram showing an enlarged view of the vicinity of a ventilation hole 47 provided in the wall portion 45 of a cylindrical member 20. The upper part of Figure 4 is a view taken from a direction approximately perpendicular to the surface of the wall portion 45. The lower part is a cross-sectional view taken from a direction approximately horizontal to the surface of the wall portion 45. In the example of Figure 4, a sliding lid 51 is provided near the ventilation hole 47 as a means of adjusting the hole area. The lid 51 is supported so as to be slidable in the direction of the arrow in the figure by a rail member 53 fixed to the wall portion 45 with adhesive or the like. The lid 51 may also be provided with a knob 55 for gripping with a finger or tool when sliding the lid 51. By providing such a structure as an adjustment means, the hole area of ​​the ventilation hole 47 that can be used for ventilation can be adjusted by sliding the lid 51.

[0019] Figure 5 is another schematic diagram showing an enlarged view of the vicinity of the ventilation hole 47 provided in the wall portion 45 of the cylindrical member 20. The upper part of Figure 5 is a view taken from a direction approximately perpendicular to the surface of the wall portion 45. The lower part is a cross-sectional view taken from a direction approximately horizontal to the surface of the wall portion 45. In the example of Figure 5, a rotatable cover 51 is provided near the ventilation hole 47 as a means of adjusting the hole area. The cover 51 is pinned to the wall portion 45 by a pinning member 57 so as to be rotatable in the direction of the arrow in the figure. By providing such a structure as an adjustment means, the area of ​​the ventilation hole 47 that can be used for ventilation can be adjusted by rotating the cover 51.

[0020] Figure 6 is another schematic diagram showing an enlarged view of the vicinity of the ventilation hole 47 provided in the wall portion 45 of the cylindrical member 20. The upper part of Figure 6 is a view from a direction approximately perpendicular to the surface of the wall portion 45. The lower part is a schematic diagram of a lid 51 that is attached to the wall portion 45. In the example of Figure 6, a removable lid 51 is provided near the ventilation hole 47 as a means of adjusting the hole area. The lid 51 has a hole portion 71 and a screw hole 73. The lid 51 can be attached, for example, by screwing it into the screw hole 75 provided in the wall portion 45. Multiple lids 51 with holes 71 of different sizes are prepared in advance. By providing such a structure as an adjustment means, the hole area of ​​the ventilation hole 47 that can be used for ventilation purposes can be adjusted by changing the multiple lids 51.

[0021] Figure 7 is another schematic diagram showing an enlarged view of the vicinity of the ventilation holes 47 provided in the wall portion 45 of the cylindrical member 20. Figure 7 is a view from a direction approximately perpendicular to the surface of the wall portion 45. In the example of Figure 7, multiple ventilation holes 47 with different hole areas are provided in advance in the wall portion 45. Closing members 77, such as rubber stoppers or lids, are prepared so that each ventilation hole 47 can be individually closed. By providing such a structure as an adjustment means, the area of ​​the ventilation holes 47 that can be used for ventilation can be adjusted by closing each ventilation hole 47 with the closing member 77 as needed. Note that each ventilation hole 47 does not need to have a different hole area; they may have the same hole area. In this case, the area of ​​the ventilation holes 47 that can be used for ventilation can be adjusted by the number of ventilation holes 47 that are closed with the closing members 77. In this way, it becomes unnecessary to prepare closing members 77 of different sizes.

[0022] The air-cooled electric motor 100 according to this embodiment, having the above configuration, allows for easy adjustment of the area of ​​the ventilation holes 47 that can be used for ventilation according to the ventilation performance of the cooling fan 4. Therefore, adjustments can be made at any time to balance the reduction in cooling performance of the electric motor body 1 with the reduction in whistling noise.

[0023] While embodiments of this disclosure have been described in detail above, this disclosure is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the spirit of the invention or from the idea and intent of this disclosure derived from the claims and their equivalents. For example, the order of operations and processes in the embodiments described above are shown as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0024] The following are additional notes regarding embodiments of the present disclosure. (Addendum 1) An air-cooled electric motor (100) according to one aspect of the present disclosure includes an electric motor body (1) having a through hole in the rotating shaft, a supply unit (3) that supplies fluid to the through hole (10), a cylindrical member (20) surrounding the supply unit (3), and a cooling fan (4) provided on the side of the cylindrical member (20) opposite to the electric motor body (1), wherein the cylindrical member (20) is provided with a plurality of passages (41) that allow cooling air to flow toward the cooling fan (4), and the plurality of passages (41) are positioned to surround the supply unit (3) and to be isolated from the supply unit (3). In addition, the supply unit (3) is positioned at a distance from each other to form a window (5) that allows the supply unit (3) to be viewed from the outside, and a wall (45) is positioned between the supply unit (3) and the cooling fan (4) side so as to obstruct the intake of air around the supply unit (3) by the cooling fan (4), and the multiple passages (41) are connected so that the cooling air that has flowed through the multiple isolated passages (41) converges on the cooling fan (4) side of the wall (45), and at least one ventilation hole (47) that communicates with the supply unit (3) is provided in the wall (45).

[0025] (Note 2) An air-cooled electric motor (100) according to another aspect of the present disclosure is provided with means for adjusting the total area available for ventilation of the ventilation holes (47) provided in the wall portion (45) on the cooling fan (4) side of the supply unit (3). (Note 3) The adjusting means provided in an air-cooled electric motor (100) according to another aspect of the present disclosure is a cover (51) that can adjust the degree to which it blocks the ventilation holes (47).

[0026] (Note 4) The adjusting means provided in the air-cooled electric motor (100) according to another aspect of the present disclosure is a cover (51) that is placed over the vicinity of the ventilation holes (47) having a plurality of different holes (71), and the total area of ​​the ventilation holes (47) that can be used for ventilation is adjusted by changing the cover (51). (Note 5) The air-cooled electric motor (100) according to another aspect of the present disclosure has a plurality of ventilation holes (47), and the adjusting means is a blocking member (77) that closes the ventilation holes (47), and the total area of ​​the ventilation holes (47) that can be used for ventilation is adjusted by selecting which ventilation holes (47) to close.

[0027] 1. Electric motor body 2. Rotating shaft 3. Rotary coupling 4. Cooling fan 5. Window section 10. Through hole 11. Hose 13. Cooling air passage 20. Cylindrical member 41. Passage section 45. Wall section 47. Ventilation hole 51. Cover 77. Closure member

Claims

1. An air-cooled electric motor comprising: an electric motor body having a through hole in the rotating shaft; a supply unit for supplying fluid to the through hole; a cylindrical member surrounding the supply unit; and a cooling fan provided on the side of the cylindrical member opposite to the electric motor body, wherein the cylindrical member is provided with a plurality of passages for circulating cooling air toward the cooling fan, the plurality of passages are spaced apart from each other so as to surround the supply unit and be isolated from the supply unit, and form a window so as to allow the supply unit to be viewed from the outside, a wall is provided between the supply unit and the cooling fan so as to prevent the cooling fan from drawing in air around the supply unit, the plurality of passages are connected so as to converge on the cooling fan side of the wall so as to allow the cooling air that has circulated through the isolated plurality of passages to converge, and at least one ventilation hole communicating with the supply unit is provided in the wall.

2. The air-cooled electric motor according to claim 1, further comprising means for adjusting the total area usable for ventilation purposes of the ventilation holes provided in the wall portion on the cooling fan side of the supply unit.

3. The air-cooled electric motor according to claim 2, wherein the means for adjustment is a lid that can adjust the degree to which it blocks the ventilation holes.

4. The air-cooled electric motor according to claim 2, wherein the means for adjustment is a cover placed over the vicinity of the ventilation hole having a plurality of different holes, and the total area of ​​the ventilation hole that can be used for ventilation is adjusted by replacing the cover.

5. The air-cooled electric motor according to claim 2, wherein there are multiple ventilation holes, and the adjusting means is a blocking member that closes the ventilation holes, and by selecting which ventilation holes to close, the total area of ​​the ventilation holes that can be used for ventilation is adjusted.

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