JPH04117151A - micro motor - Google Patents

Abstract

PURPOSE:To suppress vibration and to produce a stabilized output by mounting two frictional members on a motor shaft, housing a slip mechanism comprising a spring, the frictional members, and the like, in a motor housing thereby shortening the axial length of the motor shaft at the output end thereof. CONSTITUTION:Frictional members 57, 58 comprise D-cut members, which can advance and retract in the axial direction of a motor shaft 10, and rotate together with the motor shaft 10. A slip mechanism is constituted of a slip ring 59, E-rings 55, 56 and the frictional members 57, 58. A motor gear 60 serves as a member for positioning the motor shaft 10 in the thrust direction. Rotation of a rotor 51 is transmitted through frictional force, to be produced between one frictional member 57 and the rotor 51 and the frictional force produced between the other frictional member 58 and the rotor 51, to the motor shaft 10. Since the slip mechanism can be housed in a motor housing 1, axial length of the motor shaft 10 can be shortened at the output end thereof resulting in suppression of vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a micromotor suitable for use, for example, in driving an autofocus lens (hereinafter referred to as AF lens) of a camera.

[Conventional technology]

Conventionally, this type of micromotor has been constructed as a coreless motor as shown in FIGS. 2 and 3. To explain this based on the same figure, in the same figure, what is indicated by reference numeral 1 is a motor housing serving as a yoke that has a shaft insertion hole 2 in the center of its bottom surface, and is formed entirely of a cylindrical housing with a bottom. There is. A bracket 3 holds a brush 5 connected to the motor cord 4, and is mounted inside the opening of the motor housing 1.

Reference numeral 6 denotes a cylindrical holder extending in the axial direction of the shaft insertion hole 2, and is housed in the motor housing l. This holder 6 is formed integrally with the motor housing 1. Reference numeral 7 denotes a stator made of magget, which is fixed to the outer peripheral surface of the holder 6 and housed within the motor housing 1. Reference numerals 8 and 9 denote two bearings arranged in parallel with a gap in the axial direction, and are fixed to the inner circumferential surface of each opening of the holder 7. Reference numeral 10 denotes a motor shaft exposed inside and outside of the motor housing 1, which is connected to both the bearings 8.
9, and is inserted through the holder 6. A first E-IJ song 1 and a second E-ring 12 as a retaining ring are attached at intervals in the axial direction to the insertion end of the motor shaft 10 that is exposed outside the motor housing 1. has been done. Reference numeral 13 denotes a cylindrical rotor with a bottom, which is fixed to the insertion end facing into the motor shaft 10, and has a coil holder having a cylindrical part 14 for attaching a commutator, which protrudes in the center opposite to the stator 7. It consists of a ring 15 and a coil ring 16 held by the coil holding ring 15 and formed by winding a special coil in a cylindrical shape in multiple layers and extending around the stator 7. It is housed within the housing l.

Reference numerals 17 to 19 denote first to third D-cut washers as friction members arranged in parallel at intervals in the axial direction, and are provided on the outer circumferential surface of the motor shaft 10 so as to be movable forward and backward. 2
Reference numeral 0 denotes a motor gear that meshes with a transmission gear (not shown) of the reduction mechanism, and is provided on the outer peripheral surface of the motor shaft 10 so as to be movable forward and backward, and is connected to the three D-cut washers 17 to 19.
Of these, it is interposed between the second D-cut washer 18 and the third D-cut washer 19. A spring 21 presses the motor gear 20 against the second E-ring 12, and a spring 21 presses the motor gear 20 against the second E-ring 12.
The bullet is loaded between the cut washer 18 and the cut washer 18.

22 is a commutator with which the brush 5 slides, and the cylindrical portion 1
It is attached to 4.

In the micromotor configured in this manner, when the motor shaft 10 rotates by energizing the motor cord 4, this rotational force is transferred to the motor gear 20 and the second D-cut washer 18, and to the motor gear 20 and the third D-cut washer. The friction force generated between the motor gear 20
can be transmitted to.

Next, a case in which a conventional micromotor is implemented in an AF lens driving device of a camera will be described using FIG. 4.

In the same figure, the one indicated by numeral 31 indicates the motor driving force A.
This is a speed reduction mechanism that transmits transmission to the F lens (not shown), and is comprised of five transmission gears 32 to 36, and is interposed between the motor gear 20 and the coupling 37. Note that 38 is an encoder section consisting of a porous disk 39 and a photo ink clubter 40. If there is no output from the encoder section 38 for a certain period of time, the power to the motor is cut off.

By the way, in this type of AF lens drive device, a slip machine is used that transmits rotational force to the motor gear 20 by frictional force generated between the motor gear 20 and the second D-cut washer 18 and between the third D-cut washer 19 and the motor gear 20. Micromotors with IIA are used for the following reasons. In other words, the micromotor driven at the rated torque is on the AF lens side.

close proximity of the lens extension by a motor (not shown).

When a sudden stop occurs at the oo end, the rated torque +α is applied to the reduction mechanism interposed between the stopper (not shown) and the motor gear 20.
This is because the above-mentioned impact force acts and it is necessary to alleviate this impact force. In particular, in the case of a micromotor that obtains a large amount of power by rotating at a high speed, the inertia energy of the motor rotor generated when the motor rotor suddenly stops is extremely large, so the slip mechanism A described above is unnecessary. In this case, the slip mechanism A includes the E-rings 11, 12. D power.

It is composed of toilet seats 17 to 19 and a spring 21.

[Problem to be solved by the invention]

However, in the conventional micromotor, the E-rings 11, 12 . D cant washer 17
19 and the spring 21 are arranged at the output end of the motor shaft 10 (the insertion end exposed outside the motor housing 1 of both insertion ends of the motor shaft 10 through which the holder 6 is inserted). There is a problem in that the axial length of the output end of the motor shaft 10 becomes large, and when the motor is driven, it tends to run out and vibrate, making it impossible to obtain a stable output. Furthermore, due to the recent demand for downsizing of equipment, there is often no room for the motor shaft 10 to protrude out of the motor housing 1 for a long time, and therefore the number of turns of the spring 21 is limited. As a result, there is a problem in that the spring 21 has a low spring constant and cannot obtain a stable compressive force, resulting in variations in slip torque. Furthermore, setting the slip mechanism A consisting of the spring 21 and the like at the output end of the motor shaft 11 means that the spring and the like are usually installed after the motor is assembled, and when this is installed, thrust is applied to the parts inside the motor housing 1. There was a problem in that the motor component parts were damaged due to the impact force acting in the direction.

The present invention was made in view of the above circumstances, and it is possible to obtain a stable output, and also to prevent variations in the torque of the SJ knob and damage to the motor component parts when installing the spring cap. It provides micro motors.

[Means to solve the problem]

A micromotor according to the present invention includes a bottomed cylindrical rotor held at an insertion end facing into a motor housing, and a motor shaft is provided with two friction members arranged inside and outside of this rotor. Among the friction members, at least the friction member in the rotor is constituted by a friction member that can move back and forth in the axial direction, and this friction member is biased by a spring in a direction to press the rotor against another friction member. .

[For production]

In the present invention, when the rotor rotates, this rotational force is applied to the motor shaft by the friction force generated between one of the two friction members in the motor housing and the rotor, and between the other friction member and the rotor. can be transmitted.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be explained in detail by the Example shown in the figure.

FIG. 1 is a sectional view showing a micromotor according to the present invention.
In this figure, the same members as in FIGS. 2 to 4 are designated by the same reference numerals, and detailed explanations will be omitted. In the figure, a rotor indicated by the reference numeral 51 is a cylindrical rotor with a bottom, which is held at the insertion end facing into the motor housing 1 among the two insertion ends of the motor shaft 10, and the stator is held in the center of the rotor. A coil holding ring 53 having a cylindrical part 52 for attaching a commutator protrudes on the side opposite to the coil holding ring 53, and a special coil held by this coil holding ring 53 is formed by winding it in a cylindrical shape in multiple layers. The coil ring 54 extends around the stator 7 and is disposed outside the stator 7. Reference numerals 55 and 56 are two E-rings serving as retaining rings, which are disposed inside and outside the rotor 51, and are arranged in parallel on the motor shaft 10 with a space therebetween.

57 and 58 are two friction members arranged inside and outside the rotor 51, and are located between the E-rings 55 and 56,
It is provided on the motor shaft 10. Both friction members 57 and 58 are formed by cut members that can move forward and backward in the axial direction of the motor shaft 10, and are configured to rotate together with the motor shaft 10 when the motor is driven. One of the friction members 57 and 58 serves also as the bearing 9.

A spring 59 biases the rotor 51 in a direction to press the friction member 58, and is disposed around the motor shaft IO in the cylindrical body 6, and is attached to the E ring 55.
and the friction member 57. This spring 59. The E-rings 55 and 56 and the friction members 5758 constitute a slip mechanism B having the same function as the slip mechanism A. A motor gear 6o meshes with a transmission gear (not shown) of the reduction mechanism, and is fixed to the outer peripheral surface of the motor shaft 10. This motor gear 60 also serves as a thrust direction positioning member for the motor shaft 10. 61 is a first spring receiver interposed between the spring 59 and the E-ring 55, and 62 is a second spring receiver interposed between the spring 59 and the friction member 57.

In the micromotor configured in this way, when the rotor 51 rotates, this rotational force is transferred to one of the friction members 57.
and rotor 51, and the other friction member 58 and rotor 51
The frictional force generated therebetween can be transmitted to the motor shaft 10.

Therefore, in this embodiment, since the slip mechanism B can be housed in the motor housing 1, the axial length of the output end of the motor shaft 10 can be shortened, which reduces runout when the motor is driven.

The generation of vibration can be prevented.

Furthermore, in this embodiment, the fact that the slip mechanism B can be housed in the motor housing 1 makes it possible to effectively utilize the punt space in the holder 6, making it possible to use the spring 59 with a sufficient number of turns as a spring. The spring constant is low and stable compressive force can be obtained.

Furthermore, in this embodiment, the fact that the slip mechanism B can be housed in the motor housing 1 means that a spring or the like can be incorporated into the motor shaft 10 when the motor Mi is standing, so that the thrust direction acting on the parts in the motor housing 1 can be adjusted. Impact force can be alleviated.

In this embodiment, a case is shown in which both the friction members 5758 are movable in the axial direction of the motor shaft 10, but the present invention is not limited to this. If the structure is such that it can move forward and backward, the same effects as in the embodiment can be achieved.

Further, in this embodiment, an example in which the present invention is applied to a precision device such as a camera is shown, but the present invention is not limited to this, and it goes without saying that it can be applied to other electronic devices.

〔Effect of the invention〕

As explained above, according to the present invention, the motor shaft is provided with a bottomed cylindrical rotor held at the insertion end facing into the motor housing, and two friction members arranged inside and outside the rotor. Of these two friction members, at least the friction member in the rotor is constituted by a friction member that can move back and forth in the axial direction, and this friction member is biased by a spring in a direction to press the rotor against the other friction member. Therefore, when the rotor rotates, this rotational force can be transmitted to the motor shaft by the friction force generated between one friction member and the rotor and between the other friction member and the rotor.

Therefore, since the slip mechanism consisting of a spring, friction member, etc. can be housed in the motor housing, the axial length of the output end of the motor shaft can be shortened, and the occurrence of runout and vibration when the motor is driven can be prevented. stable output can be obtained. In addition, being able to house the slip mechanism inside the motor housing means that the dead space inside the cylinder can be used effectively, allowing the use of springs with a sufficient number of turns, resulting in low spring constants and stable compression. It is possible to obtain sufficient force and prevent variations in slip torque from occurring. Furthermore, the fact that the slip mechanism can be housed inside the motor housing means that springs and the like can be incorporated into the motor shaft when assembling the motor, making it possible to reduce the impact force in the thrust direction that acts on parts, etc. inside the motor housing. It is also possible to prevent damage to motor components during assembly.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating a micromotor according to the present invention.
2 and 3 are a cross-sectional view and a perspective view showing a conventional micromotor, and FIG. 4 is a cross-sectional view showing an example of the use of a conventional micromotor. 1...Motor housing, 2...Shaft insertion hole, 6...Holding body, 5...Plan, 7...
Stator, IO...Motor shaft, 22...
Commutator, 51...Rotor, 52...Cylindrical part, 5
3... Coil holding ring, 54... Carp/L, TW
, 55. 56...E ring, 57.58...
Friction member, 59...spring.

Claims (1)

[Scope of Claims] A motor housing having a shaft insertion hole; a cylindrical body housed within the motor housing and extending in the axial direction of the shaft insertion hole; a motor shaft rotatably supported on the axis of the stator and inserted into the cylindrical body; and an insertion end facing into the motor housing among both insertion ends of the motor shaft. a bottomed cylindrical rotor held at an end and disposed outside the stator, and two friction members arranged inside and outside the rotor are provided on the motor shaft, and both friction members At least the friction member in the rotor is configured by a friction member that can move forward and backward in the axial direction, and the friction member is biased by a spring in a direction that presses the rotor against another friction member. micro motor.