JP2003194052A - Bearing structure for flywheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing structure for a flywheel at a low cost and compacted construction nevertheless capable of stable service for a long period of time even in an environment with a large temperature difference and sustaining satisfactorily a shock given when a satellite is launched off. <P>SOLUTION: The bearing structure for the flywheel is embodied on a constant preload system in which a left 10 and a right ball bearing 11 are arranged back to back and is formed in an outer ring rotation type such that a rotary shaft 12 is supported on a housing 13 rotatably. A left 14 and a right initially coned disc spring 15 as preload giving members are installed between the inner rings 10a and 11a of the respective ball bearings 10 and 11 and the rotary shaft 12 where spring seats 16 are interposed in between, in such an arrangement that the spring constant of the left disc spring 14 is lower than that of the right disc spring 15. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing structure for a flywheel, and more particularly, to a rotary shaft inside a housing by a constant-pressure preload system in which a pair of ball bearings are arranged back to back. The present invention relates to a flywheel bearing structure rotatably supported on a flywheel. 2. Description of the Related Art As a conventional flywheel bearing structure, a fixed-position preload structure as shown in FIG. Has been adopted. The reason is that an ordinary constant-pressure preload-type bearing structure cannot respond to the impact at the time of launching the satellite for the following reasons. For example, in a constant pressure preload type bearing structure using a ball bearing, if a reaction force greater than the preload value acts, the preload of the opposite (fixed side) bearing is released. For this reason, designers usually design avoiding applications in which an external force equal to or greater than the preload value acts in the anti-preload direction. In addition, in a constant pressure preload type bearing structure using an uncular ball bearing, not only does the preload of the opposite (fixed side) bearing escape due to the reaction force,
In some cases, the ball got on the corner of the raceway or the ball fell off the raceway. As an attempt to solve the above-mentioned problem, as shown in FIG. 7, Japanese Patent Laid-Open No. 5-180220 discloses that a larger thrust force in a counter thrust direction than a cylinder 42 for applying a preload to a bearing 41 is applied to a spindle. In this case, a constant-pressure preload-type bearing device 40 that stops the movement of the preload-adjusting slide body 43 in the case where the pressure is applied is described. The slide body 43 is movably supported by an annular sleeve 44 and is driven by the cylinder 42. Slide body 43
Is stopped by the frictional contact of the thin portion 46 with the slide body 43 due to the fluid pressure in the pressurizing chamber 45 formed in the annular sleeve 44, whereby the movement of each bearing 41 is stopped. The annular sleeve 44 is fitted on the inner surface of the housing 47. Further, as shown in FIG.
Japanese Patent Application Laid-Open No. 17739 discloses a bearing device 50 that switches from a constant-pressure preload type to a fixed-position preload type when a reaction force equal to or more than a preload value acts. First and second ball bearings 51,
Outer rings 51 a and 52 a of 52 are attached to a support 53. A holder 54 is attached to the outer ring 51 a of the first ball bearing 51, and the support 53 and the holder 54
A pressurizing member 55 is provided between the two. In the bearing device 50, the pressurizing member 5
The urging force of No. 5 is applied to the first ball bearing 51 via the holder 54 and to the second ball bearing 52 via the support 53, and a constant pressure preload state is set. When a load is applied in the axial direction, the holder 54 is moved in the axial direction against the urging force of the pressurizing member 55, and the positioning member (not shown) provided on the holder 54 comes into contact with the support 53. Is done. Thereby, the first and second ball bearings 51 and 52 are
The pre-load state is established via the holder 54. Further, as shown in FIG.
Japanese Patent Publication No. 87964 discloses a motor support bearing structure in which ball bearings 61 and 62 supporting the rotating shaft 60 have improved durability. Each of the ball bearings 61 and 62 rotatably supports the rotating shaft 60 on the motor housing 63. Disc springs 64, 65 are provided between the outer rings 61a, 62a of the ball bearings 61, 62 and the motor housing 63, and the disc springs 64, 65 connect the outer rings 61a, 62a to the rotating shaft. 60 is biased toward the center in the axial direction. However, among the above-mentioned conventional bearing devices, the bearing device 40 shown in FIG. 7 has a structure in which when a force in the anti-thrust direction larger than that of the cylinder 42 is applied to the spindle, the slide device is not slid. Stopping the movement of body 43
This is performed by bringing the thin portion 46 into frictional contact with the slide body 43. For this reason, there has been a problem that the movement of each bearing 41 cannot be reliably stopped. Further, in the bearing device 50 shown in FIG. 8, when a reaction force exceeding the preload value acts, the preload of the opposite (fixed) bearing 52 is released, and the preload function does not work. Was. Further, in the motor-supporting bearing structure shown in FIG. 9, the rotary shaft 60 can be smoothly rotated with respect to an axial load from any direction.
In the present bearing structure in which the arrangement of 1, 62 is face-to-face and drives a large inertial load, in order to obtain impact resistance to a shocking moment load at the time of launching a satellite,
There is a problem that it is unavoidable to increase the size as a whole, and it is not suitable for space equipment that requires compactness. Further, the flywheel is required to operate stably in space for a long period of time, and the cleanness is required to be much higher than that of various devices on the ground.
In the case of a fixed-position preload structure, this flywheel spindle measures the bearing difference width in a state where the cleanliness of each part is increased by precision cleaning, and applies an appropriate preload based on the measurement. The spacer is adjusted. Therefore, there is a problem that after the adjustment processing of the spacer, it is necessary to perform precision cleaning again in order to increase the cleanliness, which causes a high cost. The present invention provides a flywheel which is low-cost and compact, can operate stably for a long time even in a large temperature difference, and can sufficiently withstand the impact of launching a satellite. It is intended to provide a bearing structure for a vehicle. An object of the present invention is to solve the above-mentioned problem by providing a rotating shaft in a housing by a constant-pressure preloading method in which a pair of ball bearings are arranged back to back at a predetermined interval in the axial direction. An outer ring rotation type flywheel bearing structure rotatably supported, wherein a pair of preload applying members for urging the ball bearings along an axial direction is interposed between an inner ring of each ball bearing and a housing. The present invention can be achieved by a flywheel bearing structure in which one of the preloading members has a smaller spring force in the axial direction than the other preloading member. In the above-described flywheel bearing structure, for example, when a force along the axial direction acts in one direction of the housing, the ball bearing in one direction receives the force, and the received force is reduced in one direction. Is transmitted to the rotating shaft via the preload applying material on the side. At this time, the housing does not move in one direction along the axial direction. For example, when a force along the axial direction acts on the other side of the housing, the ball bearing on the other side receives the force and the preload applying material on the other side receives the force. Then, the preload applying material in the other direction contracts in response to the received force, and accordingly, the housing also moves in the other direction. At this time, the outer ring of the one-way side ball bearing also moves in the other direction, but following the movement of the outer ring, the preload applying material in one direction expands, and the inner ring of the one-way side ball bearing also moves in the other direction. Press to the side. Therefore, the ball bearing on one side does not disassemble. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a flywheel bearing structure according to the present invention will be described below in detail with reference to FIG. FIG. 1 is a cross-sectional view showing a flywheel bearing structure of the present embodiment. As shown in FIG. 1, the flywheel bearing structure of the present embodiment includes a pair of left and right ball bearings 1 in FIG. 1.
This is an outer ring rotating type bearing structure of a constant pressure preload type in which 0 and 11 are arranged back to back, and a rotating shaft 12 is rotatably supported on a housing 13. Further, between the inner rings 10 a and 11 a of the ball bearings 10 and 11 and the rotary shaft 12, disc springs 14 and 15 as a preload applying material are provided via a spring seat 16. That is, the respective disc springs 14 and 15 apply a preload to the inner rings 10a and 11a of the ball bearings 10 and 11 via the spring seat 16 toward the inside of the rotary shaft 12 in the axial direction. The ball bearings 10 and 11 include these disc springs 14 and 1
The differential pressure of 5 acts as a preload. The disc spring 14 on the left side in FIG. 1 (hereinafter referred to as the left disc spring 14) is set to have a lower spring constant than the disc spring 15 on the right side in FIG. 1 (hereinafter referred to as the right disc spring 15). Disc spring 15
The spring seat 16 is in a more contracted state and in contact with the rotating shaft 12. The spring seat 16 of the left disc spring 14 is the rotating shaft 1
2, the axial position of the rotary shaft 12 is stabilized. Even if the spring constant of the left disc spring 14 and the right disc spring 15 is the same, the same operation and effect can be obtained as long as the amount of deflection of the left disc spring 14 in the axial direction is suppressed by the spring seat 16. The amount of deflection of the left disc spring 14 is set to an amount that can sufficiently follow the amount of movement of the housing 13 when a rightward force is applied in FIG. The operation of the flywheel bearing structure according to this embodiment will be described. For example, when a leftward force in FIG. 1 acts on the housing 13, the left ball bearing 10 (hereinafter, referred to as a left ball bearing 10) in FIG. Rotating shaft 1 via spring seat 16
2 is transmitted. At this time, the housing 13 does not move leftward in FIG. For example, when a rightward force acts on the housing 13 in FIG. 1, the ball bearing 11 on the right side in FIG.
(Hereinafter referred to as right ball bearing 11) receives a force, and right disc spring 15 receives a force. Then, the right disc spring 15 contracts in accordance with the received force, and accordingly, the housing 13 also moves to the right in FIG. At this time, the outer ring 10b of the left ball bearing 10 also moves to the right in FIG. 1, but the left disc spring 14 extends following the movement of the outer ring 10b, and the inner ring 10a of the left ball bearing 10 moves to the right in FIG. Push. Therefore, the left ball bearing 10 will not be disassembled. The left and right disc springs 14 and 15 may be replaced by slit disc springs, wave washers or coil springs. Also, the left and right disc springs 14 and 15 need not necessarily have different spring constants, and it is sufficient that the left and right disc springs have different spring forces. That is, for example, it is possible to adjust the biasing force of the left and right disc springs by making the spring constants of the left and right disc springs the same and changing the bending allowance. Next, a flywheel bearing structure according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a sectional view showing a second embodiment of the flywheel bearing structure of the present invention. As shown in FIG. 2, in the flywheel bearing structure of the present embodiment, the left disc spring 20 is configured to be in close contact, and determines the axial position of the rotating shaft 12. Note that other configurations and operations are described in the first embodiment.
The description is omitted because it is similar to the embodiment. Next, a third embodiment of the bearing structure for a flywheel according to the present invention will be described with reference to FIG. FIG. 3 is a sectional view showing a third embodiment of the flywheel bearing structure of the present invention. As shown in FIG. 3, in the flywheel bearing structure of the present embodiment, the left and right ball bearings 10, 11
However, the configuration is such that a pair of ball bearings 10c and 11c are combined in parallel. The left and right ball bearings 10, 1
A spacer (not shown) may be interposed between the pair of ball bearings 10c and 11c that constitutes 1. The other configuration and operation are the same as those in the second embodiment, and thus the description thereof is omitted. Next, a fourth embodiment of the flywheel bearing structure of the present invention will be described with reference to FIG. FIG. 4 is a sectional view showing a fourth embodiment of the flywheel bearing structure of the present invention. As shown in FIG. 4, in the flywheel bearing structure of the present embodiment, the left and right disc springs 15 and 20 are provided.
Are arranged on the housing 13 side (axially inside the rotary shaft 12) from the left and right ball bearings 10 and 11 for back-to-back alignment. For other configurations and operations,
The description is omitted because it is the same as that of the second embodiment. Next, a fifth embodiment of the bearing structure for a flywheel according to the present invention will be described with reference to FIG. FIG. 5 is a sectional view showing a fifth embodiment of the flywheel bearing structure of the present invention. As shown in FIG. 5, in the flywheel bearing structure of the present embodiment, the left disc spring 30 is provided between the pair of left and right spring seats 16 and 31 in FIG. . Note that other configurations and operations are the same as those of the above-described fourth embodiment, and a description thereof will not be repeated. As described above, according to the flywheel bearing structures of the above embodiments, the left and right ball bearings 10,
This is a constant-pressure preload type in which 11 are arranged back to back, and has an outer ring rotating type bearing structure in which a rotating shaft 12 is rotatably supported by a housing 13. In addition, the inner ring 1 of each ball bearing 10, 11
Left and right disc springs 14, 15, 20, 30 as preload applying members are provided between the spring shafts 0, 11 a and the rotating shaft 12 via spring seats 16, 31.
4, 20, and 30 are set so that the spring force in the axial direction is smaller than that of the right disc spring 15. Therefore, while being inexpensive and compact, it can operate stably for a long time even with a large temperature difference, and can sufficiently withstand the impact of launching a satellite. That is, with the back-to-back structure, compactness can be achieved, high moment rigidity can be obtained, and long life can be achieved by using the constant pressure preload type. By the way, flywheels used in outer space use two types of usage, namely, an energy storage or gyro that constantly rotates, and a reaction wheel that uses a reaction force caused by starting and stopping. Controls satellite attitude. Therefore, smooth rotation is required from the stopped state to the high-speed rotation region, and high spindle rigidity is required to increase the natural frequency. Therefore,
By applying the flywheel bearing structure of each of the above embodiments, low cost, compactness, long life, stable operation, and high impact resistance can be realized. As described above, according to the flywheel bearing structure of the present invention, a pair of preloads for biasing the ball bearings in the axial direction between the inner ring of each ball bearing and the housing. An application material is interposed, and one of the preload application materials is set to have a smaller axial spring force than the other preload application material. Therefore, while being inexpensive and compact, it can operate stably for a long time even in a large temperature difference, and can sufficiently withstand the impact of launching a satellite.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a first embodiment of a flywheel bearing structure of the present invention. FIG. 2 is a sectional view showing a second embodiment of the flywheel bearing structure of the present invention. FIG. 3 is a sectional view showing a third embodiment of the flywheel bearing structure of the present invention. FIG. 4 is a sectional view showing a fourth embodiment of the flywheel bearing structure of the present invention. FIG. 5 is a sectional view showing a fifth embodiment of the flywheel bearing structure of the present invention. FIG. 6 is a sectional view showing a conventional fixed-position preload type flywheel bearing structure. FIG. 7 is a cross-sectional view showing a conventional constant-pressure preload-type bearing device. FIG. 8 is a sectional view showing a conventional bearing device. FIG. 9 is a sectional view showing a conventional motor support bearing structure. [Description of Signs] 10 Left ball bearing 10a Inner ring 10b Outer ring 11 Right ball bearing 11a Inner ring 11b Outer ring 12 Rotating shaft 13 Housing 14 Left disc spring 15 Right disc spring 16 Spring seat

Claims (1)

Claims: 1. An outer ring rotary type in which a pair of ball bearings are rotatably supported in a housing by a constant pressure preload type in which a pair of ball bearings are arranged back to back at predetermined intervals in an axial direction. In a flywheel bearing structure, a pair of preload applying materials for urging the ball bearings along an axial direction is interposed between an inner ring of each ball bearing and a housing, and among the preload applying materials, A bearing structure for a flywheel, wherein one preload applying material has a smaller axial spring force than the other preload applying material.