JP4572554B2 - motor - Google Patents

Description

  The present invention relates to an electric motor, in particular, a color wheel rotating motor.

  In a DLP (Digital Light Processing) type single-plate projector, light in any one of the RGB frequency bands is sequentially extracted from light emitted from a light source by a rotating color wheel, and irradiated to one digital micromirror device. Then, the reflected light from the digital micromirror device is guided to a predetermined screen, and an image is displayed. In such a projector, a motor for rotating a color wheel is used. In a conventional color wheel rotating motor, a rotating part to which a color wheel is attached is rotatably supported by a ball bearing.

  In Patent Document 1, in the motor for rotating the color wheel, the outer peripheral surface of the cylindrical portion of the hub is formed in a two-stage shape so that vibration transmitted from the ball bearing to the hub is not easily transmitted to the wheel hub to which the color wheel is fixed. Thus, a technique for reducing noise during motor driving is disclosed.

  In Patent Document 2, an oil-impregnated felt washer is provided in the recess of the outer diameter portion of the oil-impregnated bearing, and an oil recovery groove is formed in the outer diameter portion of the oil-impregnated bearing on the opening side of the insulator holding the oil-impregnated bearing. A technique for realizing a longer life of the bearing device by configuring a path for circulating the oil overflowing from the bearing is disclosed.

JP 2002-58225 A JP-A-5-344675

  By the way, in the projector, the inside of the housing in which each component is arranged becomes high temperature due to the heat generated by the light source. In recent years, the output of the light source tends to increase in order to improve the image quality of the projector. Depending on the design, the temperature inside the housing may be 85 ° C. or higher. In conventional color wheel rotation motors, ball bearings (ball bearings) are used as described above, so that noise becomes significant due to changes in the viscosity of grease filled in the ball bearings in a high temperature environment. There is.

  The present invention has been made in view of the above problems, and has as its main object to reduce noise during driving of a color wheel rotating motor. Another object of the present invention is to provide a method for extending the life of a motor having a sleeve formed of a porous material.

The invention according to claim 1 is an electric motor, which is formed of a rotating part having a shaft having one end fixed to a predetermined portion, and a porous material impregnated with lubricating oil, and the shaft a fixed portion having a sleeve which the other end of is inserted, and a driving mechanism to rotate with respect to the fixed part of the rotary unit about the central axis of the shaft, the inner peripheral surface of the sleeve, a circular A notched portion recessed in an annular shape, a slidable contact portion positioned on the one end side of the notched portion, and a slidable contact portion positioned on the other end side of the notched portion, and the fixing portion being the sleeve Is inserted into the bottom of the substantially cylindrical sleeve holding portion, the inner peripheral surface of the sleeve holding portion is a recess formed outward in the circumferential direction, and is held in the recess, and Position that overlaps the sliding contact part located on one end side in the axial direction Provided, anda oil-containing member in which the lubricating oil is impregnated in between the outer surface and the inner peripheral surface of the sleeve holding portion opposed to the sleeve, the oil from the outer peripheral surface of the sleeve A constant gap greater than the oozing width is formed, and the constant gap is located on the one end side from the concave portion of the sleeve holding portion.

According to a second aspect of the invention, a motor according to claim 1, having the larger diameter of the oil scattering preventing portion from said end surface abuts against the end face of one end side of said sleeve, said sleeve holding portion a position corresponding to one end surface of the sleeve in the inner peripheral surface of, and forming a small inclined face accordance inner diameter toward the said one end side, between the outer peripheral end face of the oil scattering preventing portion and the inclined surface A minute gap smaller than the fixed gap is formed.

  A third aspect of the present invention is the motor according to the first or second aspect, wherein the constant gap is 0.1 mm or more.

A fourth aspect of the present invention is the motor according to any one of the first to third aspects, wherein the constant gap includes an opening-side inner peripheral surface of the sleeve holding portion at an upper end of the recess, and an outer periphery of the sleeve. It is formed between the surfaces.

  According to the first aspect of the present invention, it is possible to prevent the lubricating oil of the motor having a sleeve formed of a porous material from being depleted, reduce the noise during driving of the motor, and extend the service life. In particular, it is possible to extend the life under a high temperature environment. Moreover, the fixed gap between the outer peripheral surface of the sleeve and the inner peripheral surface of the sleeve holding portion facing each other can prevent the lubricant from adhering to unnecessary portions outside the sleeve holding portion.

  In the invention according to claim 2, splashing of the lubricating oil from the sleeve and the sleeve holding portion can be prevented.

  In the inventions of claims 3 and 4, leakage of the lubricating oil can be further suppressed.

  FIG. 1 is a diagram showing a schematic configuration of a projector 8 that displays an image on a predetermined screen. The projector 8 reflects a light transmitted through the color wheel 811, a color wheel assembly 81 in which a disk-shaped color wheel 811 is attached to a rotating part of a motor described later, a light source 82 that emits light toward the color wheel 811, and the color wheel 811. A digital micromirror device (hereinafter referred to as “DMD”) 83 and a projection optical system 84 that projects light from DMD 83 onto a predetermined screen are provided.

  The color wheel 811 is a filter that transmits light in the R (red), G (green), and B (blue) frequency bands in three regions divided by 120 degrees in the circumferential direction, for example. Rotate to. The DMD 83 is provided with a plurality of fine reflection mirrors that can be changed in posture in two dimensions. Any of RGB light from the color wheel 811 is guided to each reflection mirror of the DMD 83 via the condenser lens 85, and differs from the projection optical system 84 or the projection optical system 84 depending on the posture of each reflection mirror. Only the light reflected toward the predetermined position and incident on the projection optical system 84 is projected onto the screen. At this time, the DMD 83 is controlled in synchronization with the rotation angle of the color wheel 811 according to a signal input from the outside, and the posture of each reflection mirror is changed at high speed. As a result, the projector 8 switches images (R image, G image, and B image) at high speed in accordance with the input signal, and a color moving image is displayed on the screen.

  FIG. 2 is a longitudinal sectional view showing the configuration of the motor 1 of the color wheel assembly 81. The motor 1 is formed of a rotating part 2 having a shaft 21 with one end fixed, and a porous material (for example, a porous sintered body) impregnated with lubricating oil and the other end of the shaft 21 (free A fixing portion 3 having a sleeve 31 into which the end) is inserted.

  The rotating part 2 has a substantially disc-shaped hub 22 with a shaft 21 fixed at the center, and the fixed part 3 side around the fixed end of the shaft 21 has a substantially cylindrical shape centered on the central axis J1 of the shaft 21. A boss portion 221 that protrudes from the center is formed. An annular color wheel mounting portion 222 to which the above-described color wheel 811 is attached via, for example, a predetermined mounting member is formed on the outer peripheral portion of the hub 22, and the outer peripheral portion of the color wheel mounting portion 222 is An annular yoke 23 protruding to the free end side (lower side in FIG. 2) of the shaft 21 is attached. An annular field magnet 24 magnetized with multiple poles is fixed to the inner peripheral surface of the yoke 23.

  The fixed portion 3 has a bottomed substantially cylindrical sleeve holding portion 32 into which the sleeve 31 is inserted. The sleeve holding portion 32 is inserted into a through hole formed in the base plate 33 extending in a direction perpendicular to the central axis J1. To be fixed. Around the sleeve holding portion 32, an armature 34 in which a plurality of salient poles provided on the annular core are wound is provided to face the central axis J <b> 1 of the field magnet 24. The field magnet 24 and the armature 34 constitute a drive mechanism of the motor 1, and the current supplied by a current supply circuit (not shown) connected to the armature 34 is controlled, so that the rotating unit 2 is connected to the shaft 21. A torque (rotational force) that rotates with respect to the fixed portion 3 about the center axis J1 is generated.

  The bottom portion of the sleeve holding portion 32 is a substantially hook-shaped cap portion 321 (that is, the sleeve holding portion 32 is configured by fixing the cap portion 321 to a substantially cylindrical member by mechanical fastening such as adhesion or caulking. .), A thrust plate 351 is provided on a surface facing upward at the center in the cap portion 321 so as to be in contact with the spherical lower end surface of the shaft 21. On the outer peripheral surface of the lower portion of the shaft 21, an annular groove 211 is formed by being annularly cut. Further, an annular retaining member 352 made of, for example, resin is provided between the cap portion 321 and the sleeve 31, and the retaining member 352 is fitted in the annular groove 211 in a non-contact state, whereby the shaft 21. Is configured to prevent the sleeve 31 from coming off the sleeve 31. Since the retaining member 352 is elastically deformed, the shaft 21 can be easily inserted into the retaining member 352 from the spherical lower end surface.

  On the fixed end side of the shaft 21, an annular oil scattering prevention portion 353 is attached which has an end surface which is in contact with the upper end surface of the sleeve 31 and whose end surface is larger than the upper end surface. The lubricating oil impregnated in the sleeve 31 is prevented from scattering from the upper surface side of the sleeve 31.

  An annular auxiliary magnet 36 that is magnetized so that both magnetic poles are arranged in the direction of the central axis J1 is provided on the outer periphery of the annular projecting portion 323 on the upper end surface of the sleeve holding portion 32. In addition, an annular magnetic body 25 is provided at a position facing the auxiliary magnet 36 with respect to the direction of the central axis J1 in the rotating unit 2. A magnetic attraction force is generated between the auxiliary magnet 36 and the magnetic body 25, and a force in the direction of inserting the shaft 21 into the sleeve 31 acts between the rotating portion 2 and the fixed portion 3. Here, since the auxiliary magnet 36 is positioned only by being arranged along the outer periphery of the annular projecting portion 323, even when the auxiliary magnet 36 is a minute member when the motor 1 is reduced in size, it is easy. Can be arranged. Note that both the auxiliary magnet 36 and the magnetic body 25 do not necessarily have an annular shape. For example, only the magnetic body 25 has an annular shape, and a plurality of auxiliary magnets 36 are disposed on the outer periphery of the annular projecting portion 323. Also good.

  Further, the inner peripheral surface 322 of the sleeve holding portion 32 is formed with a concave portion 324 that is an annular groove centered on the central axis J1, and the concave portion 324 is provided with an annular oil retaining member 37 impregnated with lubricating oil. It is done. The inner peripheral surface of the oil-containing member 37 is in contact with the outer peripheral surface of the sleeve 31, and the lubricating oil that has oozed out of the oil-containing member 37 is supplied to the sleeve 31. That is, the oil retaining member 37 serves as an oil replenishing mechanism that replenishes the lubricating oil impregnated in the sleeve 31.

  Here, when the concave portion 324 is formed in the sleeve holding portion 32, the sleeve holding portion 32 (more precisely, a substantially cylindrical member excluding the cap portion 321) is made to coincide with the center axis J1 and a predetermined rotation axis. In this state, the processing machine is chucked and rotated, and a tool is inserted into the sleeve holding portion 32 to perform processing. Therefore, the concave portion 324 that is an annular groove centered on the central axis J1 can be easily formed by cutting.

  A plurality of grooves 311 extending in the direction of the central axis J1 are formed on the outer peripheral surface of the sleeve 31. The plurality of grooves 311 serve as a breathing passage for smoothly discharging the air in the sleeve 31 to the outside when the shaft 21 is inserted into the sleeve 31 in the manufacture of the motor 1. (That is, without being pushed back by the air remaining inside).

  On the inner peripheral surface of the sleeve 31, a notch 312 is formed on the lower side of the recess 324 with respect to the central axis J1 direction. Sliding contact portions 51 and 52 that are in contact with the outer peripheral surface of the shaft 21 and the inner peripheral surface of the sleeve 31 are provided above and below the notch 312 along the central axis J1. The sliding contact portion 51 is made longer than the sliding contact portion 52 in the direction of the central axis J1 (that is, the axial length L1 of the sliding contact portion 51 shown in FIG. 2 is longer than the axial length L2 of the sliding contact portion 52).

  When the motor 1 of FIG. 2 is driven, the shaft 21 is supported by the sleeve 31 in the radial direction that is perpendicular to the central axis J1 through the lubricating oil at the sliding contact portions 51 and 52. At this time, in the motor 1, since the center of gravity of the rotating portion 2 is located above the shaft 21, the load in the radial direction is concentrated on the sliding contact portion 51 having a long axial length. (That is, the oil retaining member 37 and the sliding contact portion 51 are substantially at the same position in the direction of the central axis J1), the lubricating oil from the oil retaining member 37 is efficiently supplied to the sliding contact portion 51, The shaft 21 is stably supported in the radial direction. Further, as described above, the tip of the shaft 21 is supported in the center axis J1 direction in a constant state without being separated from the thrust plate 351 by the magnetic attraction force generated between the auxiliary magnet 36 and the magnetic body 25 ( In other words, the thrust wheel is supported), and stable rotation of the color wheel 811 is realized.

  FIG. 3 is a partially enlarged cross-sectional view showing an enlarged configuration in the vicinity of the sleeve 31, the sleeve holding portion 32, and the oil-containing member 37 of FIG. On the inner peripheral surface 322 of the sleeve holding portion 32, a constant gap 41 is formed with the outer peripheral surface of the sleeve 31 above the recess 324 (on the opening side of the sleeve holding portion 32) with respect to the central axis J1 direction. The constant gap 41 is equal to or larger than the oozing width of the lubricating oil during rotation when the shaft 21 (and the central axis J1) is in a horizontal state (that is, in a horizontal state) when the motor 1 is mounted. The gap is preferably 0.1 mm or more. The constant gap 41 prevents the lubricating oil that has oozed out of the oil-containing member 37 from being transmitted from the sleeve 31 and the sleeve holding portion 32 and leaking from the upper surface side of the sleeve 31.

  In addition, an inclined surface having an inner diameter that decreases toward the upper end side of the sleeve holding portion 32 is formed in a bowl shape at the upper end portion of the sleeve holding portion 32 that faces the outer peripheral surface of the oil scattering prevention portion 353. A minute gap 42 smaller than the constant gap 41 is formed between the inclined surface formed at the upper end portion of the sleeve holding portion 32 and the outer peripheral end face of the oil scattering prevention portion 353, so that the lubricating oil causes the sleeve holding portion 32 to move. Even when it is likely to leak to the outside, the lubricating oil is held in the sleeve holding portion 32 by the sealing structure (which can be regarded as one form of the labyrinth structure) constituted by the minute gaps 42.

  As described above, by using the motor 1 having the sleeve 31 impregnated with the lubricating oil as the motor for rotating the color wheel, it is possible to reduce the noise that has conventionally been caused by the ball of the ball bearing. Is done. Further, the sleeve 31 is inserted into the bottomed substantially cylindrical sleeve holding portion 32, and the concave portion 324 formed on the inner peripheral surface 322 of the sleeve holding portion 32 is provided with an oil-impregnated member 37 impregnated with lubricating oil, A sufficient amount of lubricating oil is secured in the sleeve holding portion 32 by the oil retaining member 37. Further, a constant gap 41 is formed on the outer peripheral surface of the sleeve 31 that faces the opening-side inner peripheral surface 322 of the sleeve holding portion 32 at the upper end of the concave portion 324, so that the lubricating oil that has oozed out from the oil-containing member 37 is removed from the sleeve 31 and It is prevented from leaking from the upper surface side of the sleeve 31 transmitted from the sleeve holding portion 32. In addition, a seal structure that prevents the lubricating oil from leaking is formed by forming a minute gap 42 between the inclined surface formed at the upper end portion of the sleeve holding portion 32 and the outer peripheral end surface of the oil scattering prevention portion 353. The lubricant is secured in the sleeve holding portion 32 while preventing the lubricant from adhering to unnecessary portions. As a result, it is possible to prevent the lubricating oil from being depleted even in a high temperature environment and to extend the life of the motor 1.

  Note that motors having sleeves (so-called oil-impregnated plain bearings) formed of a porous material impregnated with lubricating oil tend to have a short life due to exhaustion of the lubricating oil when used in a high temperature environment. For example, in a high temperature environment, it is difficult to satisfy a life generally required for a color wheel rotation motor (for example, MTTF (Mean Time to Failure) is 20,000 hours or more). On the other hand, the motor 1 according to the present embodiment has a sleeve formed of a porous material, but has a higher temperature environment than a motor of the same type that does not have a sealing structure or a lubrication mechanism. It has been confirmed that the service life of the color wheel is doubled or more, and can be used as a motor for rotating the color wheel.

  Further, by using the motor 1 as a motor for rotating the color wheel in the projector 8 described above, it is possible to suppress the generation of noise when driving the projector 8 that requires high reliability.

  Note that three or more sliding contact portions may be provided between the shaft 21 and the sleeve 31 along the central axis J1, and in this case, the oil-containing member 37 rotates among the three or more sliding contact portions. By being provided on the outer side of the portion 2 closest to the center of gravity, it is possible to efficiently supply the lubricating oil to a necessary portion and to support the shaft 21 stably in the radial direction.

  The oil-impregnated member 37 is not necessarily provided in the vicinity of the end portion on the free end side of the shaft 21 with respect to the direction of the central axis J1, and is provided closer to the free end side of the shaft 21 than the center of the sleeve 31. Compared with the case where it is provided in, it is realized that leakage of the lubricating oil is suppressed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In the above embodiment, the sleeve holding portion 32 is formed by fixing the cap portion 321 to a substantially cylindrical member. However, the sleeve holding portion may be integrally formed as a bottomed substantially cylindrical member. .

  Further, the concave portion 324 does not necessarily have to be an annular groove depending on the manufacturing method of the sleeve holding portion, and the oil retaining member 37 may also be partially provided around the sleeve 31. Furthermore, the recess 324 may be provided with an oil-impregnated member formed of, for example, felt or a porous sintered body as the oil-impregnated member.

  Instead of the oil draining oil scattering prevention portion 353 that contacts the upper end surface of the sleeve 31, an oil-impregnated scattering preventing member such as an annular oil retaining member may be provided. As a material for the oil-impregnated scattering prevention member, a material whose holding force by the capillary action of the lubricating oil is smaller than the holding force of the sleeve is selected. By doing so, the lubricating oil that has oozed out to the end face of the sleeve 31 is once held by the scattering prevention member, but after the motor operation is stopped, the lubricating oil is transferred from the scattering prevention member to the inside of the sleeve 31 as the pressure inside the sleeve decreases. It is pulled back by capillary action. As a result, not only the lubricating oil is scattered but also its evaporation is prevented, and the life can be improved.

  In the motor 1, the magnetic body 25 may be a magnet (that is, a magnetic body having magnetism), the auxiliary magnet 36 may be a magnetic body that is not a magnet, and both the magnetic body 25 and the auxiliary magnet 36 are magnets. Thus, the force in the direction of inserting the shaft 21 into the sleeve 31 may act between the rotating portion 2 and the fixed portion 3. Further, the hub 22 may be formed of a magnetic material, and a magnetic attractive force may be generated between the auxiliary magnet 36 and a portion of the hub 22 that faces the auxiliary magnet 36 in the direction of the central axis J1.

  In the above embodiment, the motor 1 is a so-called outer rotor type in which the field magnet 24 is positioned outside the armature 34, but the field magnet 24 is positioned closer to the central axis J <b> 1 than the armature 34. The so-called inner rotor type may be used.

  The motor 1 may be used for a display device other than a projector in which a screen is separately installed. For example, the motor 1 may be used for a rear projection TV device. In this case, light from the DMD is projected onto a screen that is a screen of the TV apparatus. Furthermore, the motor 1 can be used for purposes other than the display device, and may be used for a disk drive device, for example.

It is a figure which shows schematic structure of a projector. It is a longitudinal cross-sectional view which shows the structure of a motor. FIG. 3 is a partially enlarged cross-sectional view showing an enlarged configuration in the vicinity of a sleeve 31, a sleeve holding portion 32, and an oil-containing member 37 in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 2 Rotating part 3 Fixed part 8 Projector 21 Shaft 24 Field magnet 25 Magnetic body 31 Sleeve 32 Sleeve holding part 34 Armature 36 Auxiliary magnet 37 Oil-impregnated member 41 Constant gap 42 Minute gap 51, 52 Sliding part 81 Color wheel Assembly 82 Light source 83 Digital micromirror device (DMD)
84 Projection optical system 322 Inner peripheral surface 323 Annular protrusion 324 Concavity 353 Oil scattering prevention part 811 Color wheel J1 Central axis

Claims (4)

An electric motor,
A rotating part having a shaft fixed at one end to a predetermined part;
A fixing part formed of a porous material impregnated with lubricating oil and having a sleeve into which the other end of the shaft is inserted;
A drive mechanism for rotating the rotating part relative to the fixed part about the central axis of the shaft;
With
On the inner peripheral surface of the sleeve, there is provided a notch portion that is recessed in an annular shape, a sliding contact portion that is located on the one end side of the notch portion, and a sliding contact portion that is located on the other end side of the notch portion. And
The fixing part is
A bottomed substantially cylindrical sleeve holding portion into which the sleeve is inserted;
On the inner peripheral surface of the sleeve holding portion, a recess formed outward in the circumferential direction;
An oil-impregnated member that is held in the recess and is provided at a position overlapping the sliding contact portion located on the one end side in the axial direction and impregnated with the lubricating oil;
Have
A constant gap is formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the sleeve holding portion opposed to the sleeve, and the constant gap is greater than the oil oozing width from the outer peripheral surface of the sleeve. It is located in the said one end side from the said recessed part of a part, The motor characterized by the above-mentioned. The motor according to claim 1,
It has the large-diameter oil scattering preventing portion from said end surface abuts against the end face of one end side of the sleeve,
A position corresponding to one end surface of the sleeve in the inner peripheral surface of the sleeve holding portion, to form a small inclined face accordance inner diameter toward the said one end side, the outer peripheral end surface of the oil scattering preventing portion and the inclined surface A small gap smaller than the predetermined gap is formed between the motor and the motor. The motor according to claim 1 or 2,
The constant gap is 0.1 mm or more. The motor according to any one of claims 1 to 3,
The motor is characterized in that the constant gap is formed between the inner peripheral surface of the sleeve holding portion at the upper end of the recess and the outer peripheral surface of the sleeve.

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