JP2003074573A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor reducing the manufacturing cost by keeping smooth sliding movement between the bearing and the bearing housing of a motor and preventing defects of the bearing and reducing the manufacturing cost by reducing the machining mandays, the assembling mandays, the number of parts. SOLUTION: In a motor provided with a stator 9 formed of lamitated cores, a rotor 8 formed of lamitated cores, a rotary shaft 1 on which the rotor 8 is firmly fitted to the outer periphery thereof, the bearing housings 3, 10 attached to both ends of the stator 9 by projecting the front end and the rear end of the rotary shaft 1, and the bearings 2 internally fitted into the bearing housings 3, 10 respectively so as to rotatably support the rotary shaft 1, the bearing housing 3 is provided with one recession 3b formed in the vicinity of the center of the inner diametral face of the housing and a support part 3a installed to support the rotary shaft 1 at both sides of the recession 3b. In this way, the bearing 2 slides smoothly and inconveniences such as seizure of the bearing 2 or the like brought by an excessive load applied on the bearing 2 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor using a ball bearing used for driving a main shaft of a machine tool, for example.

[0002]

2. Description of the Related Art Conventionally, an electric motor using a ball bearing used for driving a main shaft of a machine tool is shown in FIG. FIG. 3 shows an electric motor used for driving a spindle of a machine tool, etc. (a) is a side sectional view of an electric motor common to the prior art and the present invention, (b) is a bearing housing part showing the first prior art FIG. 3 is an enlarged side sectional view of a bearing part. 1 is a rotary shaft, 2 is a bearing, 3 and 10 are bearing housings, 4 is a preload spring, 8 is a rotor, 9 is a stator, 11 is a stator winding, 1
2 is a fan for forced cooling, 13 is a motor housing, 14
Is a cooling hole. The electric motor is provided with a stator 9 formed of a laminated iron core around which a stator winding 11 is wound, a rotor 8 formed of the laminated iron core and a magnetic gap, and the rotor 8 fixed to the outer periphery. Of the rotating shaft 1, the load-side bearing housing 10 and the anti-load-side bearing housing 3 attached to both ends of the stator 9 with the front end and the rear end of the rotary shaft 1 protruding, respectively. The motor housing 13 is provided on the outer circumference with a space and seals the rear end portion of the stator 9. Further, the electric motor has cooling holes 14 formed along the axial direction of the stator 9.
Then, a method for cooling the entire electric motor is provided by providing a forced cooling fan 12 arranged at the rear end of the rotary shaft 1. Further, the rotating shaft 1 is rotatably supported by bearings 2 which are fitted in bearing housings 3 and 10, respectively.
The load that the rotary shaft 1 temporarily attached to the tip of the rotary shaft (not shown)
In order to absorb the axial displacement due to the reaction force in the axial direction caused by such as or the thermal stress generated by the temperature rise of the rotating shaft itself,
The bearing 2 on the anti-load side has a structure in which a pre-load spring 4 is axially sandwiched between the bearing 2 and the bearing housing 3, and a constant pre-load is applied to both the load-side and anti-load-side bearings 2.

[0003]

However, the conventional technique has the following problems. 4 is an enlarged side sectional view of the bearing housing portion and the bearing portion showing the defective state of the first conventional technique, and FIG. 5 is an enlarged view of the bearing housing portion and the bearing of the second conventional technique. In the above electric motor, for example, as shown in FIG. 4, the inner surface of the bearing housing 3 on the sliding side has poor machining accuracy, and the inner surface has an inclination θ, or the outer ring of the bearing 2 and the housing housing 3 are inclined. When the clearance between the bearing 2 and the bearing 2 is small, the bearing 2 does not slide smoothly, so that the axial displacement of the rotary shaft 1 cannot be absorbed, and an excessive load is applied to the bearing 2, which may cause a failure such as burning of the bearing 2. . The above-mentioned problem tends to be more remarkable as the electric motor rotates at a higher speed. In order to prevent the above-mentioned problems, measures such as reducing the inclination of the bearing housing 3 and properly adjusting the clearance between the bearing housing 3 and the outer ring of the bearing 2 are taken.
Processing accuracy of unit is required. Therefore, the entire inner surface of the bearing housing 3 that slides on the bearing 2 is polished,
As shown in FIG. 5, in order to prevent the bearing 2 from tilting with respect to the bearing housing 3, a wide collar 5 whose inner and outer circumferences are entirely polished is fixed to the outer ring of the bearing 2, and the gap between the collar 5 and the bearing housing 2 is fixed. I was taking measures such as sliding it in. However, with these methods, there is a problem that the number of machining steps increases, the number of assembly steps and the number of parts increase, and the manufacturing cost increases. The present invention has been made to solve the above problems, and maintains smooth sliding between the bearing of the electric motor and the bearing housing, and prevents the bearing from malfunctioning.
It is an object of the present invention to provide an electric motor that reduces manufacturing costs by reducing the number of machining steps, the number of assembly steps, and the number of parts.

[0004]

In order to solve the above problems, the present invention according to claim 1 provides a stator comprising a laminated iron core around which a stator winding is wound, and the stator and a magnetic gap. A rotor made of laminated iron core, a rotary shaft having the rotor fixed to the outer periphery, and a bearing housing attached to both ends of the stator with the front end and the rear end of the rotary shaft protruding. A bearing housing fitted in the bearing housing so as to rotatably support the rotary shaft, wherein at least one bearing housing is provided near the center of the inner diameter surface of the housing. A concave portion and support portions that support the rotary shaft are provided on both sides of the concave portion. According to a second aspect of the present invention, in the electric motor according to the first aspect, O-rings are attached to both ends of the recess, and a solid lubricant is sealed between the O-rings.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged side sectional view of a bearing housing portion and a bearing portion showing a first embodiment of the present invention. The same components as those of the prior art will be designated by the same reference numerals and the description thereof will be omitted, and only different points will be described. In the figure, 3a is a support part, 3
b is a recess. The present invention is different from the prior art in the following points. The bearing housing 3 has one recess 3b provided near the center of the inner diameter surface of the housing, that is, the surface (sliding surface) of the bearing 2 facing the outer ring, and the rotating shaft 1 is supported on both sides of the recess 3b. It is provided with the provided support part 3a. As described above, in the first embodiment of the present invention, the concave portion 3b is provided in the central portion of the bearing housing 3, which is the inner diameter surface of the bearing housing 3, and the bearing 2 is supported by the support portions 3a on both axial sides of the concave portion 3b. Therefore, the machining range requiring precision is only the support portion 3a, the machining area of the sliding surface is small, the machining is easy, and high machining accuracy can be obtained. As a result, even if the force that the outer ring of the bearing 2 tries to move in the axial direction acts, with respect to the inner surface of the bearing housing 3,
The bearing 2 slides smoothly, and the axial displacement of the rotary shaft 1 can be absorbed by the preload spring 4, so that an excessive load is not applied to the bearing 2 to cause problems such as burnout of the bearing 2. Further, as compared with the second conventional technique, an additional component for preventing the bearing inclination is not required, and the number of assembling steps, the number of machining steps, and the number of parts can be reduced.

FIG. 2 is an enlarged side sectional view of a bearing housing portion and a bearing portion showing a second embodiment of the present invention. The difference between the second embodiment and the first embodiment is that the O-rings 6 are attached to both ends of the recess 3b and the solid lubricant 7 is enclosed between the O-rings 6. Since the solid lubricant 7 is enclosed in the recess 3b of the bearing housing 3, the outer ring of the bearing 2 and the bearing housing 3 can be more smoothly and smoothly maintained for a long period of time. It is extremely large.

[0007]

As described above, the present invention has the following effects. (1) In the first embodiment, a recess is provided in the center of the bearing, which is the inner diameter surface of the bearing housing, and the bearings are supported by the support portions on both axial sides of the recess. The processing range is only the support portion, the machining area of the sliding surface is small, the processing is easy, and high processing accuracy can be obtained. As a result, even if a force acts to move the outer ring of the bearing in the axial direction, the bearing slides smoothly against the inner diameter surface of the bearing housing, and the axial displacement of the rotating shaft can be absorbed by the preload spring. Therefore, an excessive load is not applied to the bearing to cause a failure such as burning of the bearing. (2) In the second embodiment, the solid lubricant 7 is filled in the recess 3b of the bearing housing, so that the sliding between the outer ring of the bearing and the bearing housing can be maintained more smoothly and for a long time. It is possible, and the effect can be made extremely large.

[Brief description of drawings]

FIG. 1 is an enlarged side sectional view of a bearing housing portion and a bearing portion showing a first embodiment of the present invention.

FIG. 2 is an enlarged side sectional view of a bearing housing portion and a bearing portion showing a second embodiment of the present invention.

FIG. 3 is a side sectional view of an electric motor used for driving a spindle of a machine tool or the like, in which (a) is a side sectional view of the electric motor common to the prior art and the present invention, and (b) is a bearing housing showing the first prior art. FIG. 3 is an enlarged side sectional view of a bearing portion and a bearing portion.

FIG. 4 is an enlarged side sectional view of a bearing housing portion and a bearing portion showing a defective state of the first conventional technique.

FIG. 5 is an enlarged side sectional view of a bearing housing portion and a bearing portion showing a second conventional technique.

[Explanation of symbols]

1 rotation axis 2 bearings 3, 10 bearing housing 3a support part 3b recess 4 Preload spring 5 colors 6 O-ring 7 Solid lubricant 8 rotor 9 stator 11 Stator winding 12 Forced cooling fan 13 Motor housing 14 Cooling holes

Claims (2)

[Claims] [Claim 1] A stator composed of a laminated iron core wound with a stator winding, a rotor composed of a laminated iron core provided through a magnetic gap with the stator, and the rotor fixed to the outer periphery. A rotary shaft, a bearing housing attached to both ends of the stator by projecting a front end and a rear end of the rotary shaft, and an internal fitting to the bearing housing # so as to rotatably support the rotary shaft. In the electric motor having the above described bearing, the bearing housing has at least one recessed portion provided in the vicinity of the center of the inner diameter surface of the housing, and support portions that support the rotary shaft on both sides of the recessed portion. An electric motor characterized by being provided. 2. The electric motor according to claim 1, wherein O-rings are attached to both ends of the recess, and a solid lubricant is enclosed between the O-rings.