JPH068819U - Magnetic bearing - Google Patents

Abstract

(57) [Summary] [Purpose] An object of the present invention is to provide a magnetic bearing capable of obtaining both a sufficient bearing effect and a sufficient damping effect. A magnetic bearing 121 of the present invention has a shaft member 81 and a support member 85 which are arranged so as to be rotatable relative to each other via an oil film damper 111, and the shaft member 81 and the support member 85 respectively have the same polarities. It is characterized in that it is provided with magnets 105 and 107 provided so as to face each other in the radial direction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention relates to magnetic bearings.

[0002]

[Prior art]

 Japanese Patent Publication No. 3-500319 discloses a mechanical supercharger as shown in FIG. The impeller shaft 203 of the mechanical supercharger 201 is supported by a casing 209 via a bearing 205 and an oil film damper 207.

[0003]

[Problems to be solved by the device]

 The oil film 207 is expected to have a damping effect of absorbing vibration on the rotation side including the bearing 205 and a bearing effect of rotatably supporting the bearing 205. However, in order to enhance the bearing effect, it is desirable to make the oil film thinner in order to reduce runout, but if the oil film is made thinner, the damping effect will decrease and the impeller 211 will be damaged or seizure of the bearing 205 due to excessive vibration will occur. May occur and it is difficult to achieve both the bearing effect and the damping effect.

Therefore, an object of the present invention is to provide a magnetic bearing that can obtain both a sufficient bearing effect and a sufficient damping effect.

[0005]

[Means for Solving the Problems]

 The magnetic bearing according to the present invention includes a shaft member and a supporting member that are arranged so as to be rotatable relative to each other via an oil film damper, and the shaft member and the supporting member have the same poles facing each other in the axial direction and the radial direction. It is characterized by including a magnet provided with.

[0006]

[Action]

 Between the support member and the shaft member, magnets having the same poles facing each other in the axial direction and the radial direction are provided, and the rotating side including the shaft member is supported in a floating state by the repulsive magnetic force. Therefore, the rotating side can rotate about the free axis that passes through the center of gravity instead of the fixed axis that is fixed, and thus rotational vibration is greatly reduced. In this way, since a large bearing effect is obtained by the magnetic force, it is not necessary to expect a bearing effect for the oil film damper. Therefore, the oil film damper can sufficiently thicken the oil film to obtain a large damping effect.

[0007]

【Example】

 The first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 shows a mechanical supercharger in which this embodiment is used. The left and right directions are the left and right directions in these drawings, and members and the like without reference numerals are not shown.

As shown in FIG. 1, the mechanical supercharger 1 includes a belt type continuously variable transmission 3, a speed increasing unit 5, and a centrifugal air compressor type supercharger 7. The machine 3 is provided with a drive pulley 9, a driven pulley 11 and a belt 13 connecting them.

The drive pulley 9 includes a fixed flange 17 which is integral with the hollow shaft 15 and a movable flange 19 which is connected to the hollow shaft 15 so as to be movable in the axial direction. The hollow shaft 15 is supported on a support shaft 25 via bare rings 21 and 23, and the support shaft 25 is fixed to a casing 31 of the speed increasing unit 5 by a bolt 27 and a nut 29. The belt 13 is mounted between the flanges 17 and 19, and the movable flange 19 is pressed toward the fixed flange 17 side by the disc spring 35 arranged between the movable flange 19 and the retainer 33 fixed to the hollow shaft 15. Tension is applied to the belt 13. The fixing flange 17 is provided with a screw hole 37 for fixing the transmission pulley of the belt transmission mechanism, and the drive pulley 9 is rotationally driven by the crankshaft of the engine via this belt transmission mechanism.

The driven pulley 11 includes a hollow shaft 43 and a cam member 45, which are press-fitted into the input shaft 39 of the speed increasing unit 5 and locked by a nut 41, a fixed flange 47 integrated with the hollow shaft 43, and a cam member 45. And a movable flange 49 that is connected to the hollow shaft 43 via the shaft so as to be movable in the axial direction. The hollow shaft 43 is supported on the outer periphery of the boss portion 53 of the casing 31, and the input shaft 39 is supported on the inner periphery of the boss portion 53 via bearings 55 and 57. A belt 13 is mounted between the flanges 47 and 49 to connect the driven pulley 11 to the drive pulley 9. A seal 59 is arranged between the boss portion 53 and the input shaft 39.

Cam surfaces 61, 61 are respectively formed between the cam member 45 and the movable flange 49, and a fly weight 63 is arranged between them to form a centrifugal cam 65. When the drive pulley 9 rotates, the centrifugal force of the fly weight 63 is applied to the cam surfaces 61 and 61, and the generated cam thrust force presses the movable flange 49 toward the fixed flange 47 side.

When the rotational speed of the driven pulley 11 increases as the engine rotational speed increases, the above-described cam thrust force increases the pulley pitch diameter R ₂ of the driven pulley 11, and the belt tension resists the force of the disc spring 35. As a result, the pulley pitch diameter R ₁ of the drive pulley 9 becomes smaller, and the speed increasing ratio of the belt type continuously variable transmission 3 decreases. When the engine speed decreases, the cam thrust force decreases and the disc spring 35 force increases the pulley pitch diameter R _{1 and} decreases R ₂ to increase the speed increasing ratio. In this way, the rotational speed of the driven pulley 11 is kept substantially constant within the normal rotational speed range of the engine.

The speed increasing unit 5 is a planetary gear type speed increasing mechanism, the internal gear 67 is integrally formed at the right end of the input shaft 39, and the pinion gear 69 is attached to the pinion shaft 73 via a bearing 71. It is supported. The pinion shaft 73 is supported by the flange portion 75 of the casing 31, and is provided with fall-off prevention means 77 composed of screws and balls. This flange 75 is made of aluminum. As shown in the enlarged view of FIG. 2, the sun gear 79 is joined to the left end of the shaft member 81 via a stainless steel disk 83.

The driving force of the engine inputted to the speed increasing unit 5 via the belt type continuously variable transmission 3 is increased in speed from the internal gear 67 via the pinion gear 69 and the sun gear 79 to rotate the shaft member 81.

As shown in FIG. 2, the shaft member 81 is provided with flanges 87 and 89 which penetrate the cylindrical support member 85 and face both left and right ends of the support member 85. Thrust washers 91, 91 are arranged between the collars 87, 89 and the support member 85.

The impeller 93 of the supercharger 7 is joined to the right end portion of the shaft member 81, and forms the rotating body 95 together with the sun gear 79. The impeller 93 is integrally formed of ceramics. The compressor housing 97 is fixed to the casing 31 via a connecting member 101 engaged with a circumferential groove 99 of the casing 31 and a bolt 103. The impeller 93 is rotationally driven by the speed increasing unit 5 via the shaft member 81, and the supercharger 7 supplies pressurized intake air to the engine.

As shown in FIG. 2, the shaft member 81 and the support member 85 are permanent magnets 105 and 107 whose left and right ends are magnetized to have N and S poles, respectively. These magnetic fluxes are blocked by the non-magnetic flange portion 75, the disk 83, and the impeller 93 to prevent leakage to the surroundings, and the repulsive force between the opposing magnetic poles is kept high. A magnetic fluid is filled between the right flange 89 of the shaft member 81 and the flange portion 75 to form a seal 109.

An oil film damper 111 is formed between the shaft member 81 and the support member 85. Oil is supplied into the casing 31 through an oil pump, a filter for removing iron powder, and an oil plug 113. As shown in FIG. 2, this oil is supplied to the oil film damper 111 via the nozzle 115 communicating with the oil plug 113 and the oil passages 117 and 119. This oil forms the oil film damper 111 and is supplied to the speed increasing section 5 and the like through the gap between the left flange 87 and the support member 85.

Due to the repulsive force between the magnetic poles of the shaft member 81 and the support member 85, the rotating body 95 is supported in a floating state via the oil film damper 111. At this time, the rotating body 95 rotates about an axis passing through its center of gravity, and the vibration is significantly reduced. Further, the thrust force is received by the repulsion of the magnetic force between the flanges 87 and 89 of the shaft member 81 and the end of the support member 85. The large thrust force is received by the thrust washers 91, 91.

Thus, the magnetic bearing 121 is configured.

As described above, since the bearing effect is sufficiently obtained by the magnetic force, it is not necessary to give the oil film damper 111 a large bearing effect. Therefore, the oil film is thickened as much as necessary to obtain a large damping effect to sufficiently absorb the vibration of the rotating body 95 and to greatly improve the durability of the magnetic bearing 121.

In this way, it is possible to achieve both a large bearing effect and a large damping effect, the vibration and damage of the impeller 93 are prevented, the performance of the supercharger 7 is stabilized, and the durability is improved.

The magnet may be an electromagnet instead of the permanent magnet as in the above embodiment. FIG. 3 shows a second embodiment constructed by using an electromagnet. Only the differences from the first embodiment will be described below. The members having the same functions as those in the first embodiment are designated by the same reference numerals.

The shaft member 81 penetrates the support member 123. An electromagnetic coil 125 is arranged on the outer periphery of the support member 123 to form an electromagnet 127. Similar to the shaft member 81, the electromagnet 127 is excited so that the left side in FIG. 3 is the N pole and the right side is the S pole, and supports the rotating body 95 in the radial direction and the thrust direction. The electromagnet 127 is supported by the flange portion 75. An oil film is formed between the shaft member 81 and the support member 123, and an oil film damper 129 having a large damping effect is formed to absorb the vibration of the rotating body 95. Oil from the oil pump is supplied to the oil film damper 129 via the nozzle 115 and the oil passages 117 and 131. In this way, the magnetic bearing 133 is configured, and a large bearing effect is obtained due to the repulsion of the magnetic force. Therefore, the oil film of the oil film damper 129 can be thickened to obtain a sufficient damping effect.

In this embodiment, the magnetic force of the electromagnet 127 can be adjusted so that the vibration of the rotating body 95 is minimized according to the change in the rotation speed.

In this invention, in addition to directly magnetizing the shaft member and the support member, for example, a ring-shaped permanent magnet may be embedded in the shaft member and the support member so that the same poles face each other.

[0027]

[Effect of device]

 In the magnetic bearing of the present invention, the support member and the shaft member are provided with magnets having the same poles facing each other, and the shaft member side is floatingly supported so that the oil film of the oil film damper can be thickened by obtaining a sufficient bearing effect. Therefore, both a large bearing effect and a large damping effect can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a mechanical supercharger using a first embodiment.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a cross-sectional view of essential parts of a second embodiment.

FIG. 4 is a sectional view of a conventional example.

[Explanation of symbols]

 81 Shaft member 85, 123 Support member 105, 107 Permanent magnet (magnet) 111, 129 Oil film damper 121, 133 Magnetic bearing 127 Electromagnet (magnet)

Claims (1)

[Scope of utility model registration request] 1. A shaft member and a support member arranged so as to be rotatable relative to each other via an oil film damper, and the shaft member and the support member are provided with the same poles facing each other in the axial direction and the radial direction. And a magnetic bearing.