JPH11122862A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely suppress the harmful axial direction movement of a shaft which is caused by a thrust force, by a method wherein one end of the shaft is supported in a radial direction and a thrust direction by a bearing provided in a casing. SOLUTION: A sintered oil-impregnated bearing 8 which supports the right end (one end) of a shaft 1 rotatably is attached to the right side of the casing main part 3A of a stepping motor to support the right end of the shaft 1 in both a radial direction and a thrust direction. A moving unit 21 is screwed on the lead screw 1A of the shaft 1 to move the moving unit 21 in accordance with the rotation of the shaft 1. As the right end is supported in the radial direction and the thrust direction with a high precision by the oil-impregnated bearing 8, the bottom part of the bearing is pressed against the right end head part 1B of the shaft 1 to restrict the right directional position securely. With this constitution, even if a thrust force is applied to the shaft, a harmful displacement in the axial direction can be securely suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor suitable for use when a thrust force acts on a shaft extending outside a casing.

[0002]

2. Description of the Related Art Conventionally, various types of small motors have been used as driving sources for various electric components such as timers, valve opening / closing devices, and louver opening / closing devices for air conditioners. FIG. 4 shows a small-sized stepping motor 10 connected to a driving member that converts the rotational motion of a shaft into a reciprocating motion among conventional motors of this type. This stepping motor 10 has a rotor magnet 12
Is driven to rotate and its rotational force is output to the outside via the shaft 13. The casing 14 has a composite structure of a stator cup 14A and plates 14B and 14C coupled to both left and right ends thereof. ing. here,
The plate 13B located on the right side in the drawing includes a shaft 13
A radial bearing 15 for rotatably supporting the right end of the shaft 13 is attached thereto. A plate spring 16 which presses against a left end of the shaft 13 in the drawing is attached to a plate 14C located on the left in the drawing.
Is attached. The leaf spring 16 regulates the position of the shaft 13 to the left.

The conventional motor 10 is mounted on a driving member 20 for converting the rotational movement of the shaft 13 of the motor 10 into the movement of the moving body 21 in the left-right direction. That is, the motor 10 has its plate 14B
Are attached to the left side of the bracket 22 of the drive member 20 in the figure. And on the right end side of the shaft 13,
A lead screw 13 </ b> A screwed with a female screw formed in the insertion portion of the moving body 21 is formed, and the moving body 21 moves in the left and right direction in accordance with the rotation of the shaft 13. A resin bearing 23 is attached to the right side of the bracket 22 in the drawing, and one end of the shaft 13 is supported by the resin bearing 23 via a steel ball 24. The rigid ball 24 and the resin bearing 23 regulate the rightward position of the shaft 13.

[0004]

By the way, in such a conventional motor 10, when the shaft 13 rotates, the moving body 2 is moved through the lead screw 13A.
1 moves in the horizontal direction in the drawing, the shaft 1 is driven by a component force of a reaction force generated in a direction orthogonal to the mutual thread of the moving body 21 and the lead screw 13A during driving.
A thrust force acts on 3. However, since the conventional motor 10 uses a simple leaf spring 16 as a member for regulating the position of the shaft 13 in the left direction, when the shaft 13 is subjected to an axial external force, the leaf spring 16 Is distorted, and the displacement cannot be reliably suppressed. As a result, the shaft 13 is displaced in the axial direction when the movement of the moving body 21 is adjusted, so that there is a problem that the position of the moving body 21 cannot be accurately controlled.

Therefore, in addition to the leaf spring 16, a flange is formed at the base end of the lead screw 13A of the shaft 13, and a radial bearing 15 and a separate thrust bearing are incorporated into the plate 14B. It is conceivable that the above-mentioned flange portion formed on the shaft 13 is axially supported in the thrust direction.
As a result, the size of the device itself increases, and the number of parts increases, resulting in a problem that the production cost increases.

SUMMARY OF THE INVENTION The present invention has been made to effectively solve the problems of the conventional motor described above, and aims at reducing the size and weight of the motor and preventing harmful movement of the shaft in the axial direction due to the thrust force. It is an object of the present invention to provide a motor that can be reliably suppressed.

[0007]

According to the present invention, there is provided a motor according to the present invention, wherein a shaft rotatably supported inside a casing and having one end extending outside the casing is fixed in the casing. In the motor rotated by the excited excitation coil, the other end of the shaft is
The bearing provided in the casing is supported in both the radial direction and the thrust direction, and the invention according to claim 2 is characterized in that the bearing is a sintered oil-impregnated bearing. It is assumed that.

In the motor according to the first or second aspect, the other end of the shaft is supported by the bearing provided on the casing in both the radial direction and the thrust direction. Even when a thrust force is applied, the bearing can prevent harmful axial displacement of the shaft. In particular, when a sintered oil-impregnated bearing is used as the bearing according to the second aspect of the present invention, the bearing can be easily manufactured with extremely high accuracy. Accurate movement adjustment of the member becomes possible. In addition, since the oil-impregnated bearing is a single-structure oil-impregnated bearing, the size and weight of the motor can be reduced.

[0009]

1 to 3 show an embodiment in which a motor according to the present invention is applied to a small stepping motor. In FIG. 1, reference numeral 1 denotes a shaft to which a rotor magnet 2 is attached, and a lead screw 1A is formed at a left end (one end) in the figure. Further, the rotor magnet 2 is magnetized so as to be alternately different in polarity along the circumferential direction. further,
Reference numeral 3 denotes a casing, and the casing 3 has a configuration in which a mounting plate 3B is coupled to a left opening of a casing main body 3A. Inside the casing 3, two exciting coils 4 and a field plate 5
Is incorporated. A stator pole forming a magnetic pole is formed on the field plate 5, and the magnetic pole faces the outer peripheral surface of the rotor magnet 2 with a predetermined air gap. Reference numeral 6 denotes the exciting coil 4
Connection terminal.

A radial bearing 7 for rotatably supporting the shaft 1 is mounted on the mounting plate 3B, and an oil-impregnated bearing is used as the bearing 7. A sintered oil-impregnated bearing 8 that rotatably supports the right end (the other end) of the shaft 1 is attached to the right side of the casing body 3A in the drawing. The right end is supported in both the radial direction and the thrust direction. Here, the oil-impregnated bearing 8 is a bearing in which a sintered body of powder metal is impregnated with lubricating oil, and has a predetermined mechanical strength and sufficient lubricity as it is. Note that reference numeral 9
Is a positioning buffer washer formed of, for example, a synthetic resin such as nylon (trade name) and interposed between the radial bearing 7 and the rotor magnet 2.

FIGS. 2 and 3 show the shape of the oil-impregnated bearing 8. The oil-impregnated bearing 8 has a cylindrical portion 8A fitted into the opening 3A-1 of the casing body 3A of FIG.
And a bottom portion 8B located inside the right end of the cylindrical portion 8A;
An outer flange 8C is formed integrally with the outer periphery of the left end of the cylindrical portion 8A. The right end of the shaft 1 is rotatably fitted inside the cylindrical portion 8A, and the substantially semicircular right end 1B of the shaft 1 is fitted on the inner surface of the bottom 8B.
Abuts. The motor having the above configuration is, for example, the conventional motor 1 shown in FIG.
Similarly to the case 0, the moving body 21 is attached to the bracket 22 of the driving member 20 for adjusting the movement of the moving body 21 in the left-right direction via the attaching plate 3B. In this case, the tip of the shaft 1 may be pivotally supported on the bracket 22 by the steel ball 24 and the resin bearing 23, similarly to the shaft 13 of FIG.

Next, the operation of the motor having the above configuration will be described. In this motor as well, the moving body 21 can be moved in accordance with the rotation of the shaft 1 by screwing the moving body 21 to the lead screw 1A of the shaft 1 as shown in FIG. At this time, the right end in the figure of the shaft 1 is supported with high accuracy in the radial direction and the thrust direction by the oil-impregnated bearing 8, and the bottom 8B of the shaft 1 contacts the right end head 1B of the shaft 1 and The position of the shaft 1 in the right direction in FIG. 1 is surely regulated.

For this reason, for example, even when a thrust force in the right direction in the figure acts on the shaft 1 due to the movement resistance of the moving body 21, the displacement can be reliably suppressed. Further, the thrust force acting in the left direction in the drawing is supported by the resin bearing 23 on the driving member 20 side. However, even when the thrust bearing is not provided on the driving member 20 side, the positioning buffer is not provided. Excessive movement is prevented by the washer 9. As a result, even when a thrust force acts on the shaft 1 during the movement adjustment of the moving body 21, no harmful axial displacement of the shaft 1 occurs. In addition, since the oil-impregnated bearing 8 can be easily manufactured with extremely high accuracy, accurate movement adjustment of the moving body 21 can be performed as described above. Moreover,
Since the oil-impregnated bearing 8 is a single-structure oil-impregnated bearing,
It is also possible to reduce the size and weight of the motor.

A biasing means such as a spring may be provided inside or outside the casing 3, and the shaft 1 may be biased rightward in FIG. 1 by the biasing means. In this case, the occurrence of displacement of the shaft 1 in the axial direction can be further suppressed. Further, the shaft 1 is provided with such a biasing means, and a conical hole is formed in the inner surface of the bottom portion 8B of the oil-impregnated bearing 8, and the right end head 1B of the shaft 1 is pressed into the hole so that the shaft 1 is pressed. Automatic alignment can also be performed.

Instead of providing such an urging means, a load may be applied to the shaft 1 to the right in FIG. 1 in the form of use of the motor. , It may be configured to be exerted by the washer 9. Further, in the above embodiment, as the most preferable form, the sintered oil-impregnated bearing 8
Although only the case where the right end head 1B of the shaft 1 is supported in both the radial direction and the thrust direction has been described, the present invention is not limited to this. For example, instead of the sintered oil-impregnated bearing 8, a synthetic resin It is also possible to use bearings.

[0016]

As described above, claim 1 or claim 2
According to the invention described in (1), the other end of the shaft, one end of which extends outside the casing, is supported by a bearing, preferably a sintered oil-impregnated bearing, in both the radial direction and the thrust direction. Even when the thrust force acts on the shaft while reducing the weight, harmful displacement of the shaft in the axial direction can be surely suppressed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the oil-impregnated bearing of FIG.

FIG. 3 is a view taken in the direction of the arrow III in FIG. 2;

FIG. 4 is a longitudinal sectional view illustrating an example of a conventional motor.

[Description of Signs] 1 shaft 1A lead screw 1B right end head 2 rotor magnet 3 casing 4 excitation coil 5 field plate 6 connection terminal 7 radial bearing 8 sintered oil-impregnated bearing (bearing)

Claims (2)

[Claims] 1. A motor, wherein a shaft rotatably supported inside a casing and having one end extending outside the casing is rotatably driven by an exciting coil fixed in the casing. The other end of the motor is supported in both the radial direction and the thrust direction by a bearing provided in the casing. 2. The motor according to claim 1, wherein the bearing is a sintered oil-impregnated bearing.