JPS63181635A - Molded plastic housing for small size electric motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to small electric motors of the type used in axial air impeller devices commonly found in computers, copiers, and the like. In particular, the present invention relates to an improved molded plastic housing with at least one radial end wall and an axial extension that serves as a mount for an annular stator, as well as a housing for a central shaft and its bearing.

This central axis is operatively associated with the annular rotor of the motor, which is disposed diametrically outwardly of the stator and centrally of the stator, and is capable of biasing the rotor metal of the permanent magnet type.

BACKGROUND OF THE INVENTION In a construction with an air impeller in which a small electric motor is associated, a rotor with permanent magnet elements is arranged diametrically outwardly of the rotor and is rotatably driven by the rotor to move around the device. A molded plastic air impeller may be provided to flow the air axially.

In motor and housing constructions of the type described above, it is common practice to provide a metal insert within the axial plastic housing extension to accommodate and retain the bearing that supports the entire central motor shaft. Although generally satisfactory, such structures lack economy, ease of assembly, and convenience. This is particularly disadvantageous for small, high capacity motor and air impeller systems where every penny saved is highly desirable.

PROBLEM SOLVED BY THE INVENTION It is an overall object of the present invention that an elongated body integrally extending axially from a radial end wall of the housing acts as a stator mount and a pivoting element for the shaft; It is an object of the present invention to provide an improved molded plastic housing in which the bearing is seated and directly retained within the extension of the housing, so that a reliable yet resilient bearing seat can be provided very economically. Another object is to provide an improved molded plastic housing of the type described above which effectively aligns and maintains the bearings, significantly facilitates assembly, and improves the degree of damping of vibration and noise transmission. It is to be.

To achieve the above object, the present invention includes an annular stator and a rotor disposed diametrically inwardly and outwardly, and an annular stator in the rotor that is operatively associated with and rotates with the rotor. A molded plastic housing for a compact electric motor is provided having a diametrically disposed central axis.

The housing includes at least one radially extending end wall, a centrally positioned, integrally molded stator housing, and a tubular housing portion for pivotally supporting a shaft extending radially from the end wall. ing. The radially extending tubular housing portion has intermediate axially spaced ends. 1st and 2nd
A bearing is provided at one of each end to rotatably retain the shaft. The flexibility of each end portion is increased by at least three axially extending thinned regions spaced apart along the circumference of the shaft. The length of this thinned region is approximately equal to the length of the associated bearing within the end. In the case of the bearing, the end portion 1ci of the extending tubular portion is joined with low interference at least in the thin region. Since the inner diameter of the tubular extension is made slightly smaller at least in the thin region, interference between the bearing and the tubular extension housing is reduced in the thin region. In this way, the bearing
Even if there is a slight difference in tolerance between the outer diameter of the bearing and the inner diameter of the end, the axial alignment can be maintained efficiently.

The thinned area and reduced diameter at the end of the elongate tubular housing section provides the necessary flexibility to receive the bearing in a low interference condition, while maintaining the structural integrity of the elongate tubular housing section. Since the stability can be maintained, an effective attachment body for the annular stator can be obtained. That is, the stator can be mounted on and around the tubular elongate housing portion and securely held in place. If desired, positioning of the stator's axial circumference could be facilitated by providing small axial ribs extending outwardly from the tubular portion (o> elongated housing portion).

Reducing the diameter of the end of the tubular elongated housing section
This can be achieved by providing the thinner region with a small flat section extending along the inner diameter of the tubular elongate housing section. The outer diameter surface of the bearing engages this flat surface, so that the bearing is held elastically and securely, and the bearing can be easily aligned in the axial direction. The tubular elongate housing portion can also be formed with a small shoulder to position the bearings axially and relative to the shaft in which they are fully receivable.

EXAMPLES Below, preferred embodiments of the present invention will be described. 1st
Referring to Figures 1-3, the illustrated motor-air impeller unit includes a generally rectangular housing shown generally at 1°, an air impeller having a plurality of air blades 12, 12 (five shown in the figures); and a rotor 14. This rotor 14 comprises a cup-shaped member to which an annular permanent magnet rotor 16 is attached, which cup-shaped member is connected to a second cup-shaped member 1 to which an axial air movable vane 12.12'i is attached.
8 and is fixed in the driving state. In Figure 2, axis 2
0 is attached to the inside or center of the cup-shaped member and extends downward in a cantilevered manner. The shaft 20 is a first
and second bearing, or front and rear bearing 22.24
It is pivoted on.

These bearings 22,24 are axially spaced apart within a housing section generally indicated at 26 and extend axially from a radial housing section 28 in FIG. The radial housing part 28 is fixed to the rectangular outer housing part by spoke-like elements 30.30. The motor and fan are thus held in place within the shroud. This shroud has a cylindrical shape as shown in FIGS. 1 and 4.

The radial housing portion 28, as shown, has a generally cup-like shape and has a printed circuit board 34 disposed therein. Further, the motor stator 36 is connected to the tubular housing portion 26.
attached above and around it. For this reason, the tubular housing portion 26 must have the necessary structural rigidity to support the stator 36, and also provide a resilient yet secure housing for receiving and directly holding bearings 22,24. must be provided.

As shown in FIGS. 3 and 4, the tubular housing part 2
6 is formed integrally with the radial housing part 28, is centrally positioned within the housing part 28, and extends axially therefrom. The tubular housing portion 26 has an intermediate portion 38 and opposite end portions 40,40 which serve to receive and retain the bearings 22,24.

According to the invention, each end 40.40 has its flexibility increased by at least three axially extending thinned regions spaced along the inner periphery of the shaft. It is. As shown in the figure, such a diameter-reduced thin region is 4
4 slots) as shown in Figures 4 and 5.
It is desirable to have 2.42'i. These slots 4
2.42 is open radially outward as shown and axially open at the end as shown in FIGS. 3 and 4. As shown in the figure, the thickness of the tubular housing portion 26 is approximately 1/2 or more of the thickness of the slot 42, 42. According to the invention, the extent of the thinning of the tubular elongate housing portion is at least the same as the thickness of the elongated housing portion.

The axial dimensions of the slots can vary, but are preferably less than or equal to b of the circumference of the tubular elongate housing portion, and each approximately 14 mm of the circumference of the tubular elongate housing portion, as shown. (4 slots extending over)
It is desirable to provide 42.42i. The dimensional relationships described above, and the use of a molded plastic housing made of polybutylene terephthalate, provide the bearings 22, 24 with the desired degree of elasticity and secure retention. Bearings 22, 24 include conventional rolling bearings, sleeve bearings, and the like.

Molded shoulder portion 44.4 within tubular elongated housing portion 26
4' (r) makes it easy to accurately position the bearings 22 and 24 in the axial direction. , the degree of alignment of the bearing can be improved.As shown in FIG. In particular, the inner diameter surface 46 of the tubular elongated housing portion 26 is slightly diametrically constricted at the regions or slots 42, 42'.For this purpose, as shown in FIG. Part 4.8
, 48 are provided. Alternatively, of course, a reduction in diameter is also possible by providing a region of somewhat larger diameter in the middle of the slot 42,42. In either case, the bearing 22 shown in FIG.
8.48 and an interference fit, and the opposite or rear bearing 24 is similarly mounted in axial alignment with these flats. At the rear of the shaft 20, a snap ring 50 engages the rear bearing 24 and secures it in a convenient position, and a disc bearing 52 at the front of the shaft engages the rear bearing 24.
2 and the central hub portion 54 of the cap-like member, thus securing the bearing 22 in a convenient position relative to its seat portions 44-, 44.

A stator 36 is mounted on and along the circumference of the tubular housing portion 26 and is mounted on the walls and slots of the intermediate portion 38).
42, by making the wall between 4.2 considerably thicker,
The necessary strength and rigidity of the tubular elongated housing section is achieved.

Furthermore, the structural integrity of the tubular housing part 26 with respect to the radial housing part 28 is ensured by the considerable thickness of the fin-shaped components 56.56, which fin-shaped components 56. (i
radial housing part 28 between l-slots 42,42
is connected to.

As shown in Drawing 9, slots) 4.2 and 42 are the first
In the embodiment disclosed in Figures 5 to 5, the alignment is along the axis (I5). In the optional embodiment of FIGS. 6-8, the slots 42a, 42a are generally similar to the slots 42, 42 described above, but the tubular housing portion 26.
The front part of a has slots 42a, 4- in its rear part.
2α in the direction of rotation of the axis. The tubular housing portion 26α is provided with radially extending ribs. This rib extends axially at 62 and can be used to mount the stator around its axial circumference during assembly. In FIG. 8, the flat portions 48a and 48α are adapted to be interfering with the bearing installed in the tubular housing, as in FIG. 5, and in FIGS. 7 and 8, the shoulder portion 44 .44, shoulder part 44
(L + 44 a is provided.

From the above discussion, it appears that molded plastic housings can utilize plastic materials such as polybutylene terephthalate to provide the robustness, stiffness, strength, etc. necessary for the construction of air impellers for small motors of the type described above. .

Such plastics are relatively resistant to attack by chemicals, water, oil, etc., and are also excellent electrical insulators. This is an important point in constructing a small air impeller unit. Plastics also provide significant vibration and noise transmission damping and can be manufactured using economical molding methods. The bearing of the present invention is resiliently and firmly held in alignment and direct engagement with the tubular housing portion, resulting in a relatively simple assembly process.

Moreover, the bearings effectively align and maintain alignment while providing the structural integrity necessary to mount the annular stator. In this way, it is possible to assemble a small motor efficiently, to have excellent operational efficiency, and to construct it extremely economically.

[Brief explanation of the drawing]

FIG. 1 is an elevational view of an electric motor driven axial air impeller embodying the improved motor housing of the present invention; FIG.
FIG. 3 is a schematic enlarged vertical cross-sectional view of the motor, impeller, and housing shown here as a whole; FIG. FIG. 4 is a perspective view of the improved housing of the present invention showing the axially extending portion of the housing in which the stator is mounted and the shaft is supported; FIG. 5 is a perspective view of the housing with the bearing installed therein; FIG. 6 is a generally enlarged perspective view of a further embodiment of the improved housing of the present invention; FIG. 7 is a generally enlarged end view of the axially extending portion of the housing of FIG. and FIG. 8 is an end view of the housing portion of FIGS. 6 and 7. (Explanation of main symbols) 10...Housing 12 Mountain blade 14...Rotor 18 River force sprue-shaped member 20' shaft 22
, 24... Bearing 26 - Tubular axially extending housing part 28... Radially extending housing part 3 6... Stator 38... Middle part 40... Both ends 42... Slot 48... Flat support Department
50... Snap ring 52... Disc spring
54...Central knob part 56...Fin-shaped component FIG, 5 48a FIG, 7 □Excitement□

Claims (14)

[Claims] (1) An annular stator and rotor arranged in a radially inner and outer positional relationship, and operably related to and rotatable with the annular rotor arranged diametrically within the stator. a molded plastic housing for a small electric motor having at least one radially extending end wall and a centrally positioned integrally molded stator fixture; a tubular housing portion for pivotally supporting the shaft; the tubular housing portion extends axially from the end wall, and further has opposite ends spaced apart from each other in the axial direction at an intermediate position; first and second bearings capable of being received and retained, each end having at least three reduced diameter thinned regions spaced apart along the circumference of the shaft and extending in the axial direction; increasing the flexibility of the associated bearing over at least substantially its entire length, each said bearing and its associated end having a close fit, at least in said reduced diameter region;
and a molded plastic housing, wherein the annular stator is mounted on and along the circumference of the tubular elongated housing portion. (2) said rotor is in the form of an annular permanent magnet with an operably associated air impeller disposed diametrically outward and rotatably driven by said rotor; A molded plastic housing for a small electric motor as claimed in claim 1. (3) Increase the flexibility of the bearing-receiving end by forming the reduced-diameter thin region into an axially extending slot that opens radially outward and also opens the axially outer end of each end. A molded plastic housing for a small electric motor as claimed in claim 1. (4) Each end of the elongated tubular housing portion is formed with slots spaced equidistantly along the axial circumference and having axially extending open ends. Molded plastic housings for small electric motors as described in Scope No. 3. (5) the intermediate section of the tubular elongate housing section extends annularly without interruption, with axial ends of the slots reaching each axial end, increasing the structural integrity of the intermediate section; A molded plastic housing for a small motor as set forth in claim 3. (6) An axially elongated slot at one end of the tubular elongate housing portion is axially aligned with a corresponding axially elongated slot at the other end. Molded plastic housing for small electric motors. (7) an axially elongated slot at one end is displaced along an axial circumference and is axially misaligned with a corresponding slot at the other end of the axially elongated housing portion; A molded plastic housing for a small electric motor as claimed in claim 3. (8) an axially extending rib is formed along at least a portion of the tubular axially extending portion of the housing and extends radially outwardly, and further engages the stator and connects the stator to the housing portion; A molded plastic housing for a small electric motor according to claim 3, characterized in that it is positioned along the axial circumference relative to the housing. 9. A molded plastic housing for a small electric motor as set forth in claim 3, wherein the thickness of each slot is at least 1/2 of the thickness of the tubular axially extending housing portion. (10) The molded plastic housing for a small electric motor according to claim 9, wherein the thickness of each slot is approximately 1/2 or more of the thickness of the axially extending housing portion. (11) The molded plastic housing according to claim 3, wherein the axial circumferential dimension of each of the slots is one-third or less of the circumference of the tubular elongated housing portion. 12. The compact device of claim 11, further comprising four slots, each slot extending approximately one quarter of the circumference of the tubular elongated housing portion. Molded plastic housing for electric motors. (13) The reduced diameter of the thin region is arranged in the middle of the slot on the inner diameter surface of the tubular elongated housing part, and the number is the same as the number of the slots so that the thin region can be engaged with the outer diameter surface of the bearing. A molded plastic housing for a small electric motor according to claim 3, characterized in that it is provided by a flat part. (14) the plastic of the housing assembly is polybutylene terephthalate, and the rotor is in the form of an annular permanent magnet, and the air impeller is also made of the polybutylene terephthalate and is operatively associated with the rotor. 4. A molded plastic housing for a small electric motor as claimed in claim 3, characterized in that it is arranged diametrically outwardly of the rotor so that it can be rotated by the rotor.