JP3558709B2 - Motor with hydrodynamic bearing means - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a motor. More specifically, the present invention relates to a motor including a hydrodynamic bearing.
[0002]
[Prior art]
Heretofore, spindle motors using hydrodynamic bearings, for example, as shown in FIG. 4, are known to those skilled in the art. In a known spindle motor 1 using a hydrodynamic bearing as shown in FIG. 4, a lower end of a shaft 4 is fixed to a boss 3 of a fixed base member 2, and a radius of the boss 3 The stator 5 is fixed outwardly in the direction by appropriate means. A reduced diameter portion 6 is provided at the upper end of the shaft 4, a thrust plate 7 is fitted and fixed to the reduced diameter portion 6, and the upper surface of the thrust plate 7 is similarly fitted to the reduced diameter portion 6. The holding bush 8 holds. A cover plate 9 is disposed radially outward of the bush 8 and on the upper surface of the thrust plate 7. A sleeve member 10 is provided radially outward of the cover plate 9, and the cover plate 9 and the sleeve member 10 are fixed to each other, and these constitute a shaft holding member. Furthermore, a part of the sleeve member 10 holds the thrust plate 7 and extends therefrom below this thrust plate, this sleeve 11 bearing a radial hydrodynamic bearing means 12 formed in the middle of the shaft 4. ing. The sleeve member 10 supports the rotor magnet 13 at a position facing the stator 5 radially outward of the stator 5. Furthermore, the sleeve member 10 has a hub 14 radially outward, and the hub 14 holds a disk (not shown). Oil is interposed between the upper surface of the thrust plate 7 and the lower surface of the cover plate 9 and between the lower surface of the thrust plate 7 and the sleeve member 10 to constitute thrust hydrodynamic bearing means. Oil is interposed between the fluid dynamic bearing 10 and the hydraulic fluid bearing means.
[0003]
[Problems to be solved by the invention]
Thus, such a spinned motor rotates at an extremely high speed during operation and frequently repeats a stopped state and a rotated state, so that air often enters air. If air is mixed in the oil, the mixed air is often not discharged to the outside but remains as bubbles in the oil. When air bubbles accumulate in the oil, for example, when the temperature of the oil rises, the air bubbles expand because the temperature expansion coefficient of the air is larger than that of the oil, and the oil may jump out of the bearing portion.
[0004]
Further, in a motor provided with this kind of hydrodynamic bearing means, there has been no reservoir for holding excess oil, that is, a so-called oil reservoir. For this reason, it is necessary to strictly measure the amount of oil interposed in the bearing portion. If the amount of oil is larger than a predetermined value, there is a risk that excess oil leaks from the bearing portion to the outside. In addition, since it is not possible to retain excess oil in the bearing portion in advance in this way, if the bearing is used for a long time, the oil evaporates, but in such a case, the oil in the bearing portion decreases, This causes seizure or the like, and as a result, the life of the bearing may be shortened.
[0005]
The present invention solves the above-mentioned problems, and provides a motor having hydrodynamic bearing means capable of effectively preventing oil leakage and preventing burning due to insufficient oil supply. is there.
[0006]
A motor provided with the hydrodynamic bearing means according to the present invention includes a shaft, a thrust plate provided on the shaft, and a shaft provided so as to cover the shaft and the thrust plate and supported by the shaft and the thrust plate. A thrust plate and the shaft holding member, the thrust hydrodynamic bearing means is interposed between the thrust plate and the shaft holding member, and the radial hydrodynamic bearing means is interposed between the shaft holding member and the shaft. I have. An oil reservoir in which oil exists and an air chamber in which air exists are provided between the outer peripheral surface of the thrust plate and the shaft holding member, and the thrust plate thrusts the oil in the oil reservoir. An oil supply path for supplying the pressure fluid bearing means and an air path for allowing the air chamber to communicate with the atmosphere are provided.
[0007]
[Action]
In the motor of the present invention, the oil reservoir and the air chamber are provided between the outer peripheral surface of the thrust plate and the shaft holding member. The oil reservoir communicates with an oil supply path for supplying the oil in the reservoir to the thrust hydrodynamic bearing means. Therefore, in the thrust hydrodynamic bearing means, the oil tends to flow outward in the radial direction due to the centrifugal force generated by the rotation of the rotor. The oil is supplied to the thrust hydrodynamic bearing means through the supply path, and the shortage of oil in the thrust hydrodynamic bearing means is eliminated. In addition, since the air chamber communicates with the air path for communicating the air chamber with the atmosphere, the air collected from the oil into the air chamber is discharged to the atmosphere through the air path, and adversely affected by the air. Can be avoided. The provision of the oil reservoir and the air chamber having the function of adjusting the oil amount eliminates the need to accurately measure the amount of oil interposed in the bearing means, and the oil evaporates when the bearing is used for a long time. Thus, even if the oil in the bearing means decreases, sufficient oil for preventing seizure can be held in advance.
[0008]
【Example】
FIG. 1 shows a main part of an embodiment of the motor of the present invention. In FIG. 1, the illustrated motor includes a shaft 21 whose lower end is fixedly held to a boss (not shown) of a fixed base member. A reduced diameter portion 22 is provided at the upper end of the shaft 21. A thrust plate 23 is mounted on the reduced diameter portion 22, and the thrust plate 23 is fixed to the reduced diameter portion 22 by a bush 24, similarly to the related art. A cover plate 25 is disposed radially outward of the bush 24 and on the upper surface of the thrust plate 23. A sleeve member 26 is attached to the cover plate 25 as shown in FIG. Also in this example, the cover plate 23 and the sleeve member 26 are fixed to each other to form a shaft holding member. A part of the sleeve member 26 holds the peripheral side surface of the thrust plate 23 and extends therefrom below the thrust plate 23, and further supports a radial hydrodynamic bearing means 27 provided in the middle of the shaft 21. . The radial hydrodynamic bearing means 27 is composed of a pair of bearing grooves 28 and 29 formed in the shaft 21 at intervals in the axial direction, and may be formed on the inner peripheral surface of the sleeve member 26 instead of the shaft 21. it can. It is fixed holding the stay data by the boss portion suitable means to the radially outwardly of the base member that holds the shaft 21 (not shown). As shown in FIG. 4, the sleeve member 26 supports a rotor magnet (not shown) at a position facing the stator outside in the radial direction of the stator. Further, as shown in FIG. 4, the sleeve member 26 has a hub (not shown) on the outside in the radial direction, and a magnetic disk (not shown) is held on the hub. Thus, thrust hydrodynamic bearing means is provided between the thrust plate 23 and the cover plate 25 and the sleeve member 26 surrounding the upper surface, the side surface and the lower surface of the thrust plate 23. Between the member 26, a radial hydrodynamic bearing means is provided. In the embodiment, the thrust hydrodynamic bearing means is constituted by bearing grooves formed on the upper and lower surfaces of the thrust plate 23. The bearing groove of the thrust hydrodynamic bearing means may be formed in the cover plate 25 and / or the sleeve member 26 instead of the thrust plate 23 .
[0009]
In the motor of the embodiment, a portion of the sleeve member 26 facing the corner of the thrust plate 23 and the shaft 21 is partially cut off in a triangular shape, and the air chamber 30 ( (Which constitutes a second air chamber). The air chamber 30 may be partially cut out of the thrust plate 23 to increase the volume.
[0010]
In connection with the radial dynamic pressure fluid bearing means and the thrust dynamic pressure fluid bearing means 27, it is further configured as follows. That is, between the radially inner portion 31 of the cover plate 25 and the bush 24, the outside of the motor, that is, the atmosphere passage 31 communicating with the atmosphere is defined. On the lower surface of the radially inner portion of the cover plate 25, a taper portion 32 (constituting first sealing means) which is inclined upward at a predetermined angle (a °) toward the radially inward direction therefrom. It is provided. As a result, a space 33 is formed between the lower surface portion of the cover plate 25 in the radial direction, the upper surface of the thrust plate 23, and the bush 24. Here, the angle a is desirably 5 ° to 10 °.
[0011]
As shown in FIG. 1, the corner of the sleeve member 26 extending from the lower surface of the thrust plate 23 to the radial hydrodynamic bearing means 27 of the shaft 21 is tapered off at a predetermined angle (b °, c °). Thus, the tapered portion 34 (angle b °) following the lower thrust hydrodynamic bearing means (constituting the second sealing means) and the tapered portion 35 (angle c °) following the radial hydrodynamic bearing means 27 (Constituting third sealing means). Here, it is desirable that the angle b is an angle larger than the angle a, for example, an angle of about 45 °. The angle c is automatically specified by specifying the angle b.
[0012]
Further, a lower portion of the sleeve member 26 hanging down from the corners defining the tapered portions 34 and 35 facing the shaft 21 has a predetermined angle radially outward toward the lower side of the shaft 21. A tapered portion 37 (constituting fourth sealing means) inclined at (d °) is provided. Here, the angle d is desirably, for example, 5 ° to 10 °.
[0013]
As shown in FIG. 1, the thrust plate 23, the cover plate 25, and the thrust hydrodynamic bearing means formed between the sleeve member 26 and the shaft 21 and the sleeve member 26 of the present invention. The radial hydrodynamic bearing means 27 is filled with oil. In the embodiment, the maximum gap between the tapered portion 32 (first sealing means) and the tapered portion 37 (fourth sealing means) is set so that oil does not leak from these hydrodynamic bearing means. The gap is set so as to be larger than the gap between the sleeve member 26, which makes it difficult for oil to flow out from the tapered portions 32 and 37.
[0014]
In addition to the configuration of the thrust plate 23, the configuration is as follows. Referring to FIG. 2 together with FIG. 1, in the first embodiment, a tapered groove 38 is formed on the outer peripheral surface of the thrust plate 23 in the circumferential direction. 1 and 2, the groove 38 has the smallest depth in the left peripheral portion (substantially absent in the embodiment), and has the largest right peripheral portion in FIG. 1 and FIG. To about 1 mm). The cross section of the groove 38 may be, for example, substantially V-shaped or substantially trapezoidal. In the embodiment, the tapered groove 38 is formed so that the bottom surface thereof is slightly eccentric to the left in FIGS. 1 and 2 with respect to the circular thrust plate 23, and thus, the thrust plate 23 is formed. The configuration is such that the distance between the sleeve member 26 is the smallest in one peripheral portion, and the distance between the sleeve member 26 is the largest in the other peripheral portion of the thrust plate 23. By forming the groove 38 in the thrust plate 23, the oil existing between the outer peripheral surface of the thrust plate 23 and the inner peripheral surface of the sleeve member 26 has a smaller gap along the bottom surface of the groove 38. 1 and FIG. 2, the oil tends to move to the left, and this oil collects on the left side of the groove 38 of the thrust plate 23 as shown in FIG. The portion (located on the left side of the thrust plate 23) functions as an oil reservoir 40, while the space between the outer peripheral surface of the thrust plate 23 and the sleeve member 26 where no oil exists, that is, the right side of the groove 38 ( The portion located on the right side of the thrust plate 23) functions as an air chamber 41 in which air exists. As will be easily understood, oil is interposed in the space between the outer peripheral surface of the thrust plate 23 and the region where the groove 38 does not exist and the inner peripheral surface of the sleeve member 26, and the broken line 44 in FIG. 3 shows an oil interface in a groove 38.
[0015]
The thrust plate 23 is further provided with an air passage 42 and an oil supply passage 43. The air passage 42 linearly extends to the right in FIGS. 1 and 2 in the radial direction of the thrust plate 23, and one end opening thereof is open to the air chamber 41. The other end of the air passage 42 is branched upward and downward, and the upper opening is opened in the cavity 33 (specifically, substantially outside the tapered portion 32 and free of oil). The opening opens into the air chamber 30. Therefore, when air or bubbles are mixed in the oil, gas-liquid separation is performed in the air chambers 30 and / or 41, and only gas such as air is discharged out of the machine via the air passage 42. When gas and liquid are separated only by one of the air chambers 41 and sufficient oil can be held in the oil reservoir 40, the radial dynamic pressure fluid bearing means 27 and the thrust dynamic pressure fluid The existing air chamber 30 can be omitted.
[0016]
The oil supply path 43 extends linearly to the left in FIGS. 1 and 2 in the radial direction of the thrust plate 23, and one end opening thereof opens to the oil reservoir 40. The other end of the oil supply passage 43 is branched upward and downward, and the upper opening is formed in the upper thrust hydrodynamic bearing means (specifically, in the region inside the upper thrust bearing groove where oil exists). The lower opening is open to the lower thrust hydrodynamic bearing means (specifically, the area inside the lower thrust bearing groove where oil is present). Therefore, when the oil in the thrust hydrodynamic bearing means is reduced somewhat, the oil from the oil reservoir 40 is supplied to the thrust hydrodynamic bearing means (both upper and lower sides) through the oil supply passage 43, and the thrust dynamic pressure is reduced. Seizure or the like due to a decrease in oil in the fluid bearing means is reliably prevented. Incidentally, the oil reservoir 40, along with the air chamber 30 acts as an oil amount adjusting space for accommodating a spare oil, thus exactly the amount of oil that is interposed thrust hydrodynamic bearing means and radial hydrodynamic bearing means In addition, even if the oil evaporates when used for a long time and the oil in the bearing means decreases, sufficient oil enough to prevent seizure can be retained in advance.
[0017]
FIG. 3 shows a main part of a modified example of the motor, and the same members as those in the embodiment of FIGS. Referring to FIG. 3, a concave groove 52 having substantially the same depth is formed on the outer peripheral surface of thrust plate 23 except for a part thereof (the left portion in FIG. 3). The cross section of the groove 52 may be, for example, substantially V-shaped or substantially trapezoidal, as in the above-described example. By forming the concave groove 52, the space between the thrust plate 23 and the sleeve member 26 at one peripheral portion (the left peripheral portion in FIG. 3) is reduced, and the other peripheral portions (portions other than the one peripheral portion) are formed. In this case, the distance from the sleeve member 26 increases. Therefore, the oil interposed between the outer peripheral surface of the thrust plate 23 and the inner peripheral surface of the sleeve member 26 exists in a region other than the groove 52, and tends to gather at both ends of the groove 52. Therefore, oil collects on the left peripheral surface portion of the thrust plate 23, and this portion functions as an oil reservoir 40. On the other hand, the space between the outer peripheral surface of the thrust plate 23 and the sleeve member 26 where no oil exists, that is, the groove The middle part of 52 (the part located on the right part of the thrust plate 23) functions as an air chamber 41 in which air exists, and this air chamber 41 acts as an oil amount adjustment space. Note that a broken line 53 indicates an oil boundary surface in the groove 52.
[0018]
An air passage 42 and an oil supply passage 43 are provided in the thrust plate 23 as in the embodiment of FIGS. The air passage 42 extends linearly rightward in FIG. 3, and one end of the air passage 42 opens into the air chamber 41. The other end of the air passage 42 is branched upward and downward to open to the cavity 33 and the air chamber 30 (see FIG. 1), as in the above embodiment. The oil supply path 43 extends linearly to the left in FIG. 3, one end opening of which opens into the oil reservoir 40, and the other end of the oil supply path 43 branches upward and downward to form upper and lower sides. Thrust hydrodynamic bearing means.
[0019]
Other configurations of this modification are substantially the same as those of the embodiment shown in FIGS. 1 and 2, and as will be easily understood, in this modification, substantially the same operation and effect as those of the above embodiment are achieved. Is done.
[0020]
In the above embodiment, the present invention is applied to a fixed shaft type motor. However, the present invention can be applied to a shaft rotating type motor.
[0021]
【The invention's effect】
In the motor of the present invention, the oil reservoir 40 and the air chamber 41 are provided between the outer peripheral surface of the thrust plate 23 and the shaft holding member. The oil reservoir 40 communicates with an oil supply passage 43 for supplying the oil in the reservoir 40 to the thrust hydrodynamic bearing means. Therefore, in the thrust hydrodynamic bearing means, the oil tends to flow outward in the radial direction due to the centrifugal force generated by the rotation of the motor, but even if such a tendency occurs, the oil from the oil reservoir 40 will The oil is supplied to the thrust hydrodynamic bearing means through the oil supply passage 43, and the shortage of oil in the thrust hydrodynamic bearing means is eliminated.
Further, since the air passage 41 is communicated with the air chamber 41 to communicate the air chamber 41 with the atmosphere, the air collected in the air chamber 41 from the oil is discharged to the atmosphere through the air passage 42. Thus, the adverse effects of air can be avoided. The provision of the oil reservoir 40 and the air chamber 41 for adjusting the amount of oil eliminates the need to precisely measure the amount of oil interposed in the bearing means. It is replenished and seizure in the bearing means can be prevented.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a main part of a first embodiment of a motor according to the present invention.
FIG. 2 is a sectional view showing a thrust plate of the motor of FIG. 1 and its vicinity;
FIG. 3 is a sectional view showing a main part of a modified example of the motor of the present invention.
FIG. 4 is a sectional view showing an example of a known motor.
[Explanation of symbols]
21 shaft 23 thrust plate 25 cover plate 26 sleeve member 27 radial hydrodynamic bearing means 30 air chamber 38 concave groove 40 oil reservoir 41 air chamber 42 air path 43 oil supply path 44 oil boundary surface 52 inner surface 53 oil boundary surface

Claims (7)

A shaft, a thrust plate provided on the shaft, and a shaft holding member provided so as to cover the shaft and the thrust plate and bearing supported by the shaft and the thrust plate. Thrust plate and the shaft holding member have thrust hydrodynamic fluid bearing means interposed therebetween, and radial dynamic pressure fluid bearing means is interposed between the shaft holding member and the shaft. A motor with
An oil reservoir in which oil exists and an air chamber in which air exists are provided between an outer peripheral surface of the thrust plate and the shaft holding member, and the thrust plate has an air chamber in the oil reservoir. An oil supply path for supplying oil to the thrust hydrodynamic bearing means, and an air path for allowing the air chamber to communicate with the atmosphere are provided.
A motor provided with a hydrodynamic bearing means. The outer peripheral surface of the thrust plate has a cross section in which, except for a part thereof in the circumferential direction, the gap between the shaft holding member is the smallest at both ends and the gap between the shaft holding member is the largest at the center. A substantially V-shaped tapered groove is formed, and the tapered groove has a small space between the thrust plate and the shaft holding member and the tapered groove in the outer peripheral surface of the thrust plate. The space between the portion where the groove is not formed and the shaft holding member functions as the oil reservoir, and the space where the distance between the thrust plate and the shaft holding member is large functions as the air chamber. A motor comprising the hydrodynamic bearing means according to claim 1. A groove is formed in the outer peripheral surface of the thrust plate except for a part thereof in the circumferential direction, and in the part, a first space having a small space with the shaft holding member is defined. Defines a second space with a large space between the shaft holding member, the first space and a part of the second space function as the oil reservoir, and the remainder of the second space is the second space. A motor provided with the hydrodynamic bearing means according to claim 1, which functions as an air chamber. Thrust hydrodynamic bearing means and radial hydrodynamic bearing means A motor provided with a hydrodynamic bearing means according to any one of claims 1 to 3, wherein a second air chamber is provided between the motor and the second air chamber. The tapered portion is provided at a portion of the shaft holding member facing the corner of the shaft and the thrust plate, and the tapered portion defines the second air chamber. A motor provided with a hydrodynamic bearing means. 6. A motor provided with the hydrodynamic bearing means according to claim 4, wherein one end of the air passage opens to the air chamber, and the other end of the air passage opens to the second air chamber and the atmosphere. The thrust hydrodynamic bearing means is provided on the upper and lower sides of the thrust plate, one end of the oil supply path is open to the oil reservoir, and the other end of the oil supply path is an upper surface of the thrust plate. A motor provided with the hydrodynamic bearing means according to any one of claims 1 to 6, wherein said oil is supplied to said thrust hydrodynamic bearing means on the upper side and the lower side, said oil being opened on a lower surface.

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