阅读说明：本技术 甩油环和电动机 (Oil slinger and motor ) 是由 向井康仁 于 2019-06-05 设计创作，主要内容包括：本发明提供甩油环和电动机,该甩油环用于降低伴随着电动机的旋转而产生的噪声,该电动机具备该甩油环。固定于电动机的旋转轴的甩油环具有：设于电动机的端面的多个螺纹孔和将螺纹孔各自的一部分切掉而成的切口。甩油环的螺纹孔的深度比现有技术所涉及的甩油环的螺纹孔的深度短了与切口的深度相当的距离,因此,由螺纹孔形成的气柱的固有频率变大。因而,在使用了甩油环的情况下,能够将旋转时噪声较大的转速变换到更高的转速。(The invention provides an oil slinger and a motor, wherein the oil slinger is used for reducing noise generated along with rotation of the motor, and the motor is provided with the oil slinger. An oil slinger fixed to a rotating shaft of a motor includes: the motor includes a plurality of screw holes provided in an end surface of the motor and cutouts formed by cutting out portions of the respective screw holes. The depth of the threaded hole of the slinger is shorter than the depth of the threaded hole of the slinger according to the prior art by a distance corresponding to the depth of the notch, and therefore, the natural frequency of the air column formed by the threaded hole is increased. Therefore, when the oil slinger is used, the rotational speed at which noise is large during rotation can be converted to a higher rotational speed.)

1. An oil slinger mounted to one or both of a portion of the rotating shaft located on a forward side of the axis relative to the front bearing and a portion of the rotating shaft located on a rearward side of the rear bearing relative to the axis, in a motor including a stator, a rotor having a rotating shaft rotatable about an axis relative to the stator, and a forward bearing and a rearward bearing for rotatably supporting the rotating shaft,

the oil slinger has a plurality of threaded holes and cutouts formed by cutting out a part of each of the threaded holes.

2. The oil slinger of claim 1,

the cutout is formed to cut out each of the screw holes from an open end thereof by a recess shorter than a depth of the screw hole.

3. The oil slinger according to claim 1 or 2 characterized in that,

the cutout is formed as a slit in which a part of a side portion of the screw hole is cut out along a longitudinal direction of the screw hole.

4. The oil slinger of claim 3,

the slit is formed so as not to open to the outer side surface of the oil slinger.

5. An oil slinger mounted to one or both of a portion of the rotating shaft located on a forward side of the axis relative to the front bearing and a portion of the rotating shaft located on a rearward side of the rear bearing relative to the axis, in a motor including a stator, a rotor having a rotating shaft rotatable about an axis relative to the stator, and a forward bearing and a rearward bearing for rotatably supporting the rotating shaft,

the oil slinger has a plurality of threaded holes and a spacer formed on the downstream side of the threaded holes in the rotation direction of the rotating shaft.

6. The oil slinger according to any one of claims 1 to 5 characterized in that,

the plurality of screw holes are provided on an end surface on a side axially opposite to a side facing the inside of the motor.

7. An electric motor, characterized in that,

the motor includes the oil slinger of any one of claims 1-6.

Technical Field

The present invention relates to an oil slinger having a structure for reducing noise generated during rotation, and a motor having the oil slinger.

Background

In many cases, a motor (rotating electrical machine) for rotating a spindle of a machine tool or the like is provided with a member called an oil slinger having a plurality of screw holes, and balance weights such as headless set screws are screwed into some of the screw holes to enable balance adjustment during rotation. Therefore, when the motor (oil slinger) rotates at a high speed, noise is generated because of the presence of the screw hole to which the balance weight is not screwed.

As a conventional technique for reducing such noise, there is known a technique in which a cover is provided to cover an end surface of a spindle (see, for example, japanese patent laid-open No. 2000-132465), and a countersunk screw as a balance weight is screwed into a screw hole to make the surface on which the screw hole is formed substantially flat (see, for example, japanese patent laid-open No. 2008-132579).

Disclosure of Invention

Problems to be solved by the invention

A structure is desired that can effectively reduce noise generated along with rotation of the motor without performing work such as attachment of a cover, screwing of a countersunk screw, or the like.

Means for solving the problems

An aspect of the present disclosure is directed to an oil slinger for a motor including a stator, a rotor having a rotating shaft rotatable about an axis with respect to the stator, and a front bearing and a rear bearing for rotatably supporting the rotating shaft, the oil slinger being attached to one or both of a portion of the rotating shaft located on a front side with respect to the axis with respect to the front bearing and a portion of the rotating shaft located on a rear side with respect to the axis with respect to the rear bearing, the oil slinger including a plurality of screw holes and cutouts formed by cutting out portions of the screw holes.

According to the above aspect, the cutout may be a recess formed by cutting out each of the screw holes from an opening end of the screw hole by a distance shorter than a depth of the screw hole.

According to the above aspect, the cutout may be a slit formed by cutting out a part of a side portion of the screw hole along a longitudinal direction of the screw hole.

According to the above aspect, the slit may not be formed so as to open to the outer side surface of the oil slinger.

Another aspect of the present disclosure is an oil slinger for a motor including a stator, a rotor having a rotating shaft rotatable about an axis with respect to the stator, and a front bearing and a rear bearing for rotatably supporting the rotating shaft, the oil slinger being attached to one or both of a portion of the rotating shaft located on a front side with respect to the axis with respect to the front bearing and a portion of the rotating shaft located on a rear side with respect to the axis with respect to the rear bearing, the oil slinger having a plurality of threaded holes and spacers formed on a downstream side with respect to the threaded holes in a rotational direction of the rotating shaft.

According to the above aspect, the plurality of screw holes may be provided in an end surface on a side axially opposite to a side facing the inside of the motor.

Still another aspect of the present disclosure is a motor including the oil slinger according to the above aspect of the present disclosure.

ADVANTAGEOUS EFFECTS OF INVENTION

The invention can effectively reduce the noise generated along with the rotation of the motor.

Drawings

The objects, features and advantages of the present invention will become more apparent from the following description of the embodiments with reference to the accompanying drawings. In the drawings of the present invention,

fig. 1 is a diagram showing a schematic configuration of a motor according to a preferred embodiment of the present invention.

Fig. 2 is a view showing embodiment 1 of an oil slinger provided in the motor of fig. 1.

Fig. 3 is a diagram showing a configuration example of an oil slinger according to the related art.

Fig. 4 is a diagram for explaining a noise reduction effect by the oil slinger of fig. 2.

Fig. 5 is a graph for explaining the noise reduction effect by the oil slinger of fig. 2.

Fig. 6 is a diagram showing another example of the configuration of the oil slinger according to embodiment 1.

Fig. 7 is a view showing another configuration example of the oil slinger according to the embodiment of fig. 1.

Fig. 8 is a view showing embodiment 2 of an oil slinger provided in the motor of fig. 1.

Fig. 9 is a partially enlarged view showing a conventional oil slinger.

Fig. 10 is a partially enlarged view of the oil slinger of fig. 8.

Fig. 11 is a diagram for explaining an example in which the spacer reduces the inflow amount of air into the screw hole.

Fig. 12 is a graph for explaining the noise reduction effect by the oil slinger of fig. 8.

Fig. 13 is a diagram showing another example of the configuration of the oil slinger according to embodiment 2.

Detailed Description

Fig. 1 is an axial cross-sectional view showing a schematic structure of an electric motor (rotating electrical machine) 10 according to a preferred embodiment of the present invention. The motor 10 includes: a rotary shaft (shaft) 18 supported by a 1 st bearing (front bearing) 12 and a 2 nd bearing (rear bearing) 14 so as to be rotatable about an axis 16; a rotor (rotor)20 fitted to the outer peripheral surface of the rotating shaft 18 and rotating integrally with the rotating shaft 18; and a stator 22 having a substantially cylindrical shape and extending along the axis 16 in a manner surrounding the rotor 20.

The front bearing 12 is disposed near the front end 18a of the rotary shaft 18, and is supported by a front housing 26 fixed to the front end surface 24a of the stator core 24 by screwing or the like. The front housing 26 extends from the front end surface 24a of the stator core 24 toward the front end 18a of the rotary shaft 18, and supports (the outer ring of) a part of the rotary shaft 18 and (the front bearing 12). Further, a front cover 28 having a substantially annular shape is attached to the front housing 26. The front end 18a of the rotary shaft 18 protrudes from the front housing 26 and the front cover 28, and the rotary shaft 18 functions as an output shaft directly or indirectly coupled to a spindle of a machine tool such as a lathe or a machining center. In the present specification, for convenience, the output shaft side (left side in fig. 1) is referred to as "front", and the opposite side (right side in fig. 1) is referred to as "rear".

The rear bearing 14 is disposed in the vicinity of a rear end 18b of the rotary shaft 18 on the opposite side to the front end 18a of the rotary shaft 18. A rear housing 30 is fixed to the rear end surface 24b of the stator core 24 by screwing or the like, a support ring 32 is fixed to the rear housing 30 by screwing or the like, and the support ring 32 supports (the outer ring of) the rear bearing 14. The rear end 18b of the rotary shaft 18 protruding from the rear case 30 protrudes from a rear cover 34 attached to the rear case 30. An encoder 36 for detecting the rotational position, rotational speed, and the like of the rotary shaft 18 is attached to the rear end 18b of the rotary shaft 18.

The stator 22 includes a stator core 24 formed of a plurality of stacked electromagnetic steel plates, and a winding 38 wound around a projection (not shown) formed on an inner peripheral surface of the stator core 24. The winding 38 is fixed to the stator core 24 with resin or the like. The winding wire 38 extends along the rotation axis 16 so as to protrude from both ends of the stator core 24, and is connected to a lead wire (not shown) drawn from the terminal box 40. The wire 38 generates a rotating magnetic field by the current supplied through the lead wire, and the rotor 20 rotates integrally with the rotating shaft 18 by the generated rotating magnetic field.

In the present specification, "radially outer" refers to a direction away from the rotation axis 16 in cross section, and "radially inner" refers to a direction toward the rotation axis 16 in cross section. Also, "axial direction" or "axial direction" means a direction parallel to the rotation axis 16.

The motor 10 has at least one (two in the example of the figure) oil slinger that rotates integrally with the rotating shaft 18, and can perform balance adjustment during rotation. More specifically, an oil slinger (labyrinth) 44 is fixed by interference fit or the like to a portion of the rotary shaft 18 located on the front side of the front bearing 12 on the axis 16 (in the vicinity of the front cover 28 in the illustrated example), and the oil slinger 44 is formed with a plurality of screw holes 42 extending in the axial direction, so that foreign matter is prevented from entering the motor, and a balance weight (not shown) such as a headless setscrew is screwed into at least one of the screw holes 42, whereby balance adjustment during rotation is possible. Similarly, an oil slinger 48 is fixed by interference fit or the like to a portion of the rotary shaft 18 on the rear side of the rear bearing 14 on the axis 16 (the vicinity of the rear cover 34 in the illustrated example), and the oil slinger 48 is formed with a plurality of screw holes 46 extending in the axial direction, thereby preventing foreign matter from entering the inside of the rear cover 34, and a balance weight (not illustrated) such as a headless setscrew is screwed into some of the screw holes 46, whereby balance adjustment during rotation is enabled.

In the illustrated example, oil slingers are provided on both the front side and the rear side of the rotating shaft 18, but may be provided only on either side. Since the oil slinger 44 and the oil slinger 48 can have the same basic structure and function, only the oil slinger 48 on the rear side will be described below.

(embodiment 1)

Fig. 2 is a perspective view showing a configuration example of an oil slinger 48 according to embodiment 1, and fig. 3 is a perspective view showing a configuration example of a prior art oil slinger 49 as a comparative example. The oil slinger 48 has a plurality of screw holes 46 to which balance weights for balance adjustment are attachable and detachable, and notches 52 in which a part of each of the screw holes 46 (female threads) is cut out, and here, the screw holes 46 and the notches 52 are formed in an end surface 50 on the side axially opposite to the side facing the inside of the motor 10. More specifically, the notch 52 is formed as a recess in which each screw hole 46 is cut away from its open end (here, the end face 50) by a certain distance (shorter than the screw hole depth), and in the illustrated example, the notch 52 is an annular groove. However, the recess is not limited to this, and may be a recess in which a counterbore having a larger diameter and a shorter axial length than the screw hole 46 is formed concentrically with each screw hole 46. With such a cutout, the length of the air column formed by the threaded hole 46 is shorter than the length of the air column formed by the threaded hole 47 of fig. 3, as will be described below.

Fig. 4 is a diagram for explaining a noise reduction action by the oil slinger 48 shown in fig. 2. Here, the threaded hole 47 (see fig. 3) of the slinger 49 and the threaded hole 46 of the slinger 48 of the conventional product shown in fig. 3 are compared.

Since the inflow and outflow of air are generated by the rotation of the motor in each screw hole formed in the slinger, each screw hole functions as a kind of closed tube during the rotation. At this time, the natural frequency f of the closed tube (air column) is represented by the following expression (1) where the sound velocity is V and the length of the air column is L (n is 1, 2, 3.). As is clear from expression (1), the smaller the length L of the gas column, the larger the natural frequency f becomes.

f_2n-1＝(2n－1)/4L·V (1)

Here, the depth of the screw hole 46 (the length of the air column) of the slinger 48 according to embodiment 1 is shorter than the depth of the screw hole 47 (the length of the air column) of the slinger 49 according to the related art by a distance corresponding to the depth d of the groove 52, and therefore, the natural frequency becomes large. Therefore, when the slinger 48 is used, the rotational speed at which noise is large (extremely large) during rotation can be converted to a higher rotational speed than when the slinger 49 is used.

Fig. 5 is a graph for explaining the noise reduction effect when the oil slinger 48 shown in fig. 2 is attached to the motor 10. In fig. 5, the horizontal axis represents a dimensionless number proportional to the rotation speed of the motor, and the vertical axis represents a dimensionless number proportional to the magnitude of the sound generated with the rotation of the motor. In addition, the magnitude of the sound was measured at a fixed position separated from the oil slinger by a certain distance. As another (preferable) comparative example, a measurement result using the slinger 49 of fig. 3 is shown as a graph 58, and a measurement result using the slinger 48 of fig. 2 is shown as a graph 54, and a measurement result using the slinger 49 of fig. 3 is shown as a graph 56, and a measurement result using the slinger (which corresponds to a slinger having substantially no screw hole 47) having all the screw holes 47 of the slinger 49 of fig. 3 filled with headless setscrews or the like is shown as a graph 58.

As is clear from fig. 5, when the slinger 49 is used, the sound level becomes extremely large (graph 56) when the rotation speed is about 170, whereas when the slinger 48 is used, the sound level is considered to become extremely large in the region where the rotation speed exceeds 200 because the natural frequency is higher than the natural frequency when the slinger 49 is used as described above. Therefore, if the rotation speed of the motor is in the practical range (200 or less), the noise level can be greatly reduced compared to the conventional product by using the oil slinger 48, and the noise level can be very close to the ideal product (graph 58).

In fig. 4, it is also considered that the screw hole can be simply shortened, considering that noise can be reduced by making the air column shorter. However, in this case, in order to prevent the headless setscrew or the like from protruding largely from the end surface of the oil slinger, it is necessary to shorten the length of the headless setscrew or the like (that is, to lighten the headless setscrew), and therefore, it is difficult to obtain the original function as the balance adjustment, which is not preferable. In the embodiment 1, the depth of the screw hole from the end face is not changed by providing the notch in the end face, but the depth (the length of the air column) that affects the noise level is shortened, whereby the headless setscrew having the same length as the conventional setscrew can be used, and noise can be prevented.

Fig. 6 is a diagram showing a configuration example of an oil slinger 48a as a modification of embodiment 1. The oil slinger 48a has a plurality of screw holes 46a to which balance weights for balance adjustment are attachable and detachable, and notches 52a formed by cutting out a part of each of the screw holes 46a (female threads), and here, the screw holes 46a and the notches 52a are formed on an end surface 50a on the side axially opposite to the side facing the inside of the motor 10. The cutout 52a is formed as a slit in which a part of the side portion of the screw hole 46a is cut out along the longitudinal direction of the screw hole 46 a. In this case, since each screw hole 46a does not have a cylindrical shape, the air column itself as shown in fig. 4 is not formed even when the motor rotates. Therefore, even when the oil slinger 48a is used, the noise during rotation can be significantly reduced as compared with the conventional one.

Fig. 7 is a diagram showing a configuration example of an oil slinger 48b as another modification of embodiment 1. The oil slinger 48b has a plurality of screw holes 46b to which balance weights for balance adjustment are attachable and detachable, and notches 52b formed by cutting out a part of each of the screw holes 46b (female threads), and here, the screw holes 46b and the notches 52b are formed on an end surface 50b on the side axially opposite to the side facing the inside of the motor 10. The notch 52b is formed as a slit in which a part of the side portion of the screw hole 46b is cut out along the longitudinal direction of the screw hole 46b, similarly to the notch 52a, but the notch 52b is formed so as not to open on the outer side surface of the slinger 48b, with respect to the notch 52a opening on the outer side surface of the slinger 48 a. Therefore, when the slinger 48b is used, in addition to the noise reduction effect due to the absence of the formation of the air column as in the slinger 48a, the air flow around the outer surface of the slinger 48b during rotation is not disturbed as compared with the air flow around the outer surface when the slinger 48a is used, and therefore, a higher noise reduction effect can be expected.

In both of fig. 6 and 7, the slit (slit) is formed over the entire length of each screw hole, but even when the slit (slit) is formed over a part in the longitudinal direction thereof, the length of the air column can be actually shortened as compared with the conventional product, and therefore, a certain noise reduction effect can be obtained. The "longitudinal direction" (of the threaded hole) in the present disclosure is not limited to a direction strictly parallel to the axial direction of the threaded hole, and includes, for example, a direction forming an angle of 10 ° or less, 20 ° or less, or 30 ° or less with respect to the axial direction. The slit is not limited to a straight line, and may be, for example, a curved line or a spiral.

(embodiment 2)

Fig. 8 is a perspective view showing a configuration example of an oil slinger 48c according to embodiment 2. The oil slinger 48c has a plurality of screw holes 46c to which balance weights for balance adjustment are detachably attached, and a spacer 60 formed on the downstream side of the screw holes 46c in the rotational direction of the rotary shaft 18, wherein the screw holes 46c and the spacer 60 are formed on an end surface 50c on the opposite side to the side facing the inside of the motor 10 in the axial direction, and the spacer 60 is formed on the downstream side of the screw holes 46c on the end surface 50 c. In the illustrated example, the spacer 60 is configured as a star-shaped protrusion formed on both sides of the screw hole 46c in the rotational direction, but is not limited thereto.

Fig. 9 to 11 are diagrams for explaining the operation and effect of the spacer 60. As shown in fig. 9, which is a comparative example, in the oil slinger 49 (see fig. 3) according to the related art, when the motor rotates, an air flow (indicated by an arrow 64) in a direction substantially opposite to the rotation direction 62 is generated in the vicinity of the screw hole 47, and a certain amount of air flows into and out of the screw hole 47, which causes noise.

In contrast, in the oil slinger 48c according to embodiment 2, as shown in fig. 10, the spacer 60 provided on the end surface 50c on the downstream side of the threaded hole 46c in the rotational direction 62 deflects the air flow (indicated by the arrow 66) in the direction substantially opposite to the rotational direction 62 (more specifically, as shown in fig. 11, discharges the air in the direction away from the end surface 50 c), so that the inflow and outflow of the air into and out of the threaded hole 46 can be made smaller than those of the conventional product shown in fig. 9. As a result, noise during rotation can be suppressed.

Fig. 12 is a graph for explaining a noise reduction effect when the oil slinger 48c shown in fig. 8 is attached to the motor 10. In fig. 12, the horizontal axis represents a dimensionless number proportional to the rotation speed of the motor, and the vertical axis represents a dimensionless number proportional to the magnitude of the sound generated with the rotation of the motor. In addition, the magnitude of the sound was measured at a fixed position separated from the oil slinger by a certain distance. As another (preferable) comparative example, a measurement result using the slinger 49 of fig. 3 (which corresponds to a slinger substantially without the screw hole 47) in which all the screw holes 47 of the slinger 49 of fig. 3 are filled with headless setscrews or the like is shown as a graph 58.

As is clear from fig. 12, when the slinger 49 is used, the magnitude of the sound becomes extremely large at a rotation speed of about 170 (graph 56), and when the slinger 48c is used, the magnitude of the sound also tends to become extremely large at a rotation speed of about 170. However, since the inflow and outflow of air into and out of the screw hole 46c are greatly reduced by the spacer 60 as described above, the noise level can be greatly reduced in embodiment 2 as compared with the conventional product, and the noise level can be very close to the ideal product (pattern 58).

In the measurement of fig. 12, the height h (see fig. 11) of the spacer 60 was set to 0.5 mm. However, this is merely an example, and the number of rotations and the noise level can be appropriately changed to 1mm or less, 2mm or less, 3mm or less, and the like.

Fig. 13 is a diagram showing a configuration example of an oil slinger 48d as a modification of embodiment 2. The oil slinger 48d has a plurality of screw holes 46d to which balance weights for balance adjustment are detachably attached, and a spacer 70 formed on the downstream side of the screw holes 46d in the rotational direction of the rotary shaft 18, wherein the screw holes 46d and the spacer 70 are formed on an end surface 50d on the side axially opposite to the side facing the inside of the motor 10, and the spacer 70 is formed on the downstream side of the screw holes 46d on the end surface 50 d. In the illustrated example, the spacer 70 is configured as a protrusion extending radially from the center of rotation in the middle of the adjacent screw hole 46d on the end surface 50d, but is not limited thereto. Similarly to the case where the slinger 48c of fig. 8 is used, the inflow and outflow of air into and out of the screw hole 46d can be reduced to a large extent by the spacer 70 even in the case where the slinger 48d of fig. 13 is used, and therefore, the noise level can be reduced to a large extent as compared with the conventional product.

In any of the above embodiments, 12 screw holes are formed at equal intervals of 30 ° in the circumferential direction around the axis 16 in the end surface of the oil slinger, but the present disclosure is not limited thereto. For example, 4 screw holes may be formed at equal intervals of 90 ° in the circumferential direction in the end surface of the oil slinger, 6 screw holes may be formed at equal intervals of 60 ° in the circumferential direction, and 8 screw holes may be formed at equal intervals of 45 ° in the circumferential direction. Further, the intervals of the plurality of screw holes may not be equal, but in consideration of balance and eccentricity caused by rotation of the main shaft, it is preferable that the screw holes of the same size are formed at equal intervals in the circumferential direction on a circle concentric with the rotation center. Also, the threaded hole does not normally penetrate the slinger (the depth of the threaded hole is shorter than the axial length of the slinger). The screw hole may be provided on a surface (for example, an outer surface) other than the end surface of the slinger.

In addition, the notch and the spacer in the above-described embodiment are preferably formed so as not to impair the rotational symmetry of the oil slinger. This is because, when the oil slinger itself is not rotationally symmetrical, it is very difficult to adjust the rotational balance by inserting a headless setscrew or the like into the threaded hole.

By applying the oil slinger according to the present disclosure to a motor (rotating electrical machine), noise generated with rotation of the motor can be greatly reduced even if a cover for preventing noise is not used and a screw hole is not closed for a purpose other than balance adjustment. Further, the oil slinger according to the above embodiment can be relatively easily manufactured only by modifying the mold, and there is no significant difference in cost from the conventional product. Further, when the motor including the oil slinger according to the present disclosure is applied to a machine tool in which a main shaft is normally rotated at a high speed, such as an NC lathe or a machining center, a working environment with less noise can be realized.

According to the present disclosure, the amount of sound generated when the motor rotates due to the presence of the screw hole can be reduced significantly as compared to conventional products.