JPH08251903A - Stepping motor with lead screw - Google Patents

Abstract

PURPOSE: To obtain a high performance, small-sized stepping motor with lead screw by providing the motor shaft with preload function. CONSTITUTION: The stepping motor with lead screw comprises a fully threaded lead screw 1 having a hole of smaller diameter than the minor diameter of screw at one end, and a shaft 2 being fitted in the hole slidingly in the thrust direction. A spring 6 is inserted into the shaft insertion hole of the lead screw before inserting the shaft 2 and then the motor shaft is integrated thus providing the motor shaft with preload function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor with a lead screw used for a lens driving device used for a video camera, a floppy disk head driving device, and various OA equipment driving devices.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for downsizing, high performance, and low price of stepping motors used for downsizing, high performance, and low price of devices.

A conventional stepping motor with a lead screw will be described below with reference to the drawings.

FIG. 10 is a sectional view of a conventional stepping motor with a lead screw, FIG. 11 is a view showing a state of a shaft fitting portion of a motor shaft of the stepping motor with a lead screw, and FIG. 12 is a view showing a structure of the motor shaft. , Fig. 13
FIG. 4 is a diagram showing a state of a tip end portion of a lead screw.

In each of the drawings, 21 is a lead screw having a spherical end on one end and a hole having a diameter smaller than the root diameter of the lead screw at the other end, 22 is a shaft, 3 is a frame, and bearing 4 is Fitted and fixed. Two
Reference numeral 6 is a leaf spring that applies a preload. The leaf spring 26 abuts a spherical portion on one end of the shaft 22, and the other end of the shaft rotatably supports a motor shaft constituted by press-fitting and fixing the shaft on one end of the lead screw 21 on one side. There is. Further, the motor is centered together with the resin-made pivot bearing 8 fixed to the mounting plate 7 and the bearing 4. Reference numerals 9a and 9b denote rotor magnets, which are press-fitted by a rotor magnet rotation-preventing press-fitting portion 10 symmetrically provided on the outer diameter of the shaft 22 in the same circumferential direction as the rotor magnets and fixed by adhesion or the like to rotate integrally with the shaft 22. The motor shaft. The rotor magnets 9a, 9b are arranged in order from the shaft rear end leaf spring side 9a, 9a, 9b so as not to damage the sliding portion between the bearing 4 and the shaft 22.
It is press-fitted and fixed in the order of 9b.

[0006]

In such a conventional structure, a leaf spring is required to preload the shaft. However, with the downsizing of motors, it is difficult to obtain sufficient preload with a leaf spring having a conventional configuration, and a metal leaf spring (generally SU
Since the S material) slides on the metal shaft, noise and wear occur. Also, since the rotor magnet rotation prevention press-fitting part of the shaft is on the same circumferential direction as each rotor magnet, when press-fitting the rotor magnet from the same direction on the shaft rear end spring side, the press-fit span to the rotor magnet fixing position on the bearing side is long. There was a problem that the rotor magnet was chipped and the press-fit strength deteriorated. Further, there is a problem that the loss due to frictional force is large because the contact area between the tip portion of the lead screw and the pivot bearing is large.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a small-sized, high-performance stepping motor with a lead screw.

[0008]

The present invention provides various means for solving the above problems. The first means interposes a spring component in a hole having a diameter smaller than the root diameter of the lead screw and inserts a shaft to form a motor shaft. In this case, at least the sliding portion of the hole of the lead screw with respect to the shaft may be made of resin having good slidability. Further, with the above structure, it is possible to receive the spherical surface portion of the shaft rear end by the flat surface portion made of resin.

The second means is to dispose the rotor magnet rotation-preventing press-fitting portion of the shaft for each rotor magnet with a phase shift.

The third means is to make the tip of the lead screw into a conical structure having a spherical tip.

[0011]

According to the present invention, with the above-described structure, the first means can obtain an appropriate preload by the spring component built in the motor shaft without using the leaf spring in the miniaturization of the motor, and the shaft rear end can be obtained. It is possible to reduce the noise at the contact portion between the spring and the spring, and to reduce the noise and downsize the motor.

The second means is to dispose the rotor magnet rotation-preventing press-fitting portions symmetrically provided on the outer diameter portion of the shaft with the phases shifted for each magnet. Since each two rotor magnets have a rotor magnet rotation-stop press-fitting part whose phase is shifted, the press-fitting span of the rotor magnets can be shortened, so that a sufficient pressure input can be secured and a high-performance motor is provided. To do.

The third means provides a highly accurate motor which can reduce the frictional force between the lead screw and the resin-made pivot bearing and has a small shaft loss.

[0014]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a stepping motor with a lead screw according to a first embodiment of the present invention, and FIGS. 2 and 3 are views showing a shaft fitting portion of a motor shaft in FIG. 1, FIG. 4 and FIG. FIG. 5 is a diagram illustrating a rotation stopping mechanism of the motor shaft. In each figure, 1 is a lead screw, which has a hole having a diameter smaller than the root diameter of the lead screw.
As shown in FIG. 4, the hole has a concave portion 15 of a shaft rotation preventing mechanism that holds the convex portion 14 of the shaft 2 in the radial direction in the axial direction from the screw end on the hole side, and slides in the thrust direction between the hole and the hole. It has a spring 6 between it and the shaft 2, which is held so that it is possible. One end of the shaft 2 on one side of the motor side is spherical, and is made of resin attached to the bearing 4 fixed to the frame 3 and attached to the mounting plate 7 by being pressed and urged by the flat surface receiving portion 11 of the resin material. The pivot bearing 8 centers the motor shaft and supports the shaft 2 rotatably in the axial direction. Rotor magnets 9a and 9b are press-fitted and adhesively fixed so as to rotate integrally with the shaft 2. Further, as shown in FIG. 3, at least the lead screw 1
By using the resin material 12 in the sliding portion of the hole of the shaft 2 and the shaft 2, it is possible to reduce shaft loss, noise and wear when sliding in the thrust direction.

Further, as shown in FIG. 5, the shaft detent mechanism may have a structure in which a pin 17 is inserted into a recess 16 provided in the shaft 2 through a pin insertion hole of a lead screw so as to be slidable in a thrust direction. .

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 6 is a sectional view of a motor shaft according to a second embodiment of the present invention, and FIGS. 7 (a) and 7 (b) are respectively FIG.
It is sectional drawing of the A and B part. As shown in FIGS. 6 and 7, parts having the same configurations as those of the conventional example shown in FIG.

The outer diameter portion of the shaft 2 is provided with rotor magnet rotation preventing press-fitting portions 13a and 13b which are out of phase for every two rotor magnets symmetrically arranged.
When press-fitting the rotor magnet 9a from the side opposite to the lead screw into the rotor magnet rotation-preventing press-fitting portion 13a, 2
Since the two rotor magnet rotation stopper press-fitting portions 13a and 13b are out of phase, the press-fitting span is short and stress applied to the same portion of the rotor magnet inner diameter portion is small, so that the rotor magnet is not chipped and a sufficient pressure input is secured. be able to. Also, as shown in FIG. 8, the motor shaft has two
The shaft may have a one-piece structure having a lead screw portion instead of the one-piece structure.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to the drawings.

FIG. 9 is a view showing the state of the tip end portion of the lead screw of the stepping motor with lead screw in the third embodiment of the present invention. In FIG. 9, other configurations are the same as those of the conventional example of FIG. 10, and therefore, the same numbers are given and the description thereof is omitted.

Reference numeral 31 denotes a lead screw, which has a conical structure in which the tip end in the direction of the resin-made pivot bearing 8 has a spherical shape at the tip end, so that the contact area between the lead screw and the resin-made pivot bearing 8 is small and the frictional force is reduced. Provide a high-precision motor with little axis loss.

[0023]

As described above, according to the present invention, the motor shaft is combined with a preload function, each rotor magnet has a rotor magnet rotation preventing press-fitting portion, and the resin pivot bearing and the motor shaft slide. By reducing the dynamic loss, the motor can be downsized, and it is possible to provide a high-performance, long-life, low-noise stepping motor with a lead screw, which has a great effect.

[Brief description of drawings]

FIG. 1 is a sectional view of a stepping motor with a lead screw according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state of a shaft fitting portion of a motor shaft of the stepping motor with the lead screw.

FIG. 3 is a diagram showing a state of a shaft fitting portion of another motor shaft in the stepping motor with the lead screw.

FIG. 4 is a view for explaining a rotation preventing mechanism of a motor shaft in the stepping motor with the lead screw.

FIG. 5 is a view for explaining a rotation stopping mechanism for another motor shaft in the stepping motor with the lead screw.

FIG. 6 is a diagram showing a configuration of a motor shaft of a stepping motor with a lead screw according to a second embodiment.

FIG. 7 is a sectional view showing a rotor magnet press-fitting portion of the motor shaft of FIG. 6 in the second embodiment.

FIG. 8 is a structural diagram of another motor shaft in the second embodiment of the present invention.

FIG. 9 is a diagram showing a state of a tip end portion of a lead screw of a stepping motor with a lead screw according to a third embodiment of the present invention.

FIG. 10 is a sectional view of a conventional stepping motor with a lead screw.

FIG. 11 is a diagram showing a state of a shaft fitting portion of a motor shaft of the stepping motor with the lead screw.

FIG. 12 is a diagram showing a configuration of a motor shaft of the stepping motor with the lead screw.

FIG. 13 is a view showing a state of a lead screw tip portion of the stepping motor with the lead screw.

[Explanation of symbols]

1, 21, 31 Lead screw 2, 22 Shaft 3 Frame 4 Bearing 6 Spring 7 Mounting plate 8 Pivot bearing 9a, 9b Rotor magnet 10, 13a, 13b Rotor magnet rotation stop press-fitting part 11 Flat receiving part 12 Resin material 14 Convex part 15 , 16 recesses 17 pins 26 leaf springs

Claims (5)

[Claims] 1. A fully screw-shaped lead screw having a hole having a diameter smaller than a root diameter of the lead screw at one end on one side, and a shaft fitted in the hole and held slidably in a thrust direction, A stepping motor with a lead screw, wherein a preload is applied to a motor shaft through a spring at a fitting portion between the lead screw and the shaft. 2. A stepping motor with a lead screw according to claim 1, wherein at least the shaft sliding portion of the shaft insertion hole of the lead screw has a sliding member made of resin. 3. A full-screw type lead screw having a hole having a diameter smaller than the root diameter of the lead screw at one end on one side, and a screw screw fitted to the hole and symmetrically applied to an outer diameter constituting a motor shaft. A shaft having two rotor magnet detent press-fitting portions, and two rotor magnets fixed to the two rotor magnet detent press-fitting portions of the shaft, respectively. A stepping motor with a lead screw characterized by shifting the phase of the press-fitting part. 4. The stepping motor with lead screw according to claim 3, wherein the motor shaft is not a two-body structure but a one-body structure shaft having a lead screw portion. 5. A lead screw, a mounting plate, and a resin-made pivot bearing mounted on the mounting plate, wherein the tip end portion of the lead screw in the pivot bearing direction has a conical structure with a spherical tip shape. Stepping motor with lead screw.