JP3804164B2 - Linear motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a linear motor using a flexure bearing as a support mechanism for supporting a mover in a non-contact manner with respect to a stator.
[0002]
[Prior art]
In a linear motor, a flexure bearing using the spring property of a leaf spring member may be used as a support mechanism that supports the mover in a non-contact manner with respect to the stator. A linear motor employing a flexure bearing is incorporated as a driving device for a piston of a direct acting compressor, for example, and a non-contact piston support mechanism supports the operating piston in a non-contact state with respect to the cylinder. It is intended to prevent gas deterioration and sealing wear caused by sliding contact between the cylinder and the cylinder, and to prevent deterioration of the compressor performance. One of the formats is described in a publication “Mitsubishi Electric Technical Report, Vol. 67, No. 8, 1993”.
[0003]
Furekushi catcher Bearings is a portion in which a slit is formed extending spirally to the outer peripheral edge from the center side to the leaf spring member is a spring body, fixed to the stator and the outer peripheral edge portion in the housing of the compressor, the center The part is fixed to the shaft part (movable element) of the working piston to support the working piston. When the working piston is supported, the spring body is flexible in the orthogonal direction and highly rigid in the parallel direction. The piston is supported in a stable state, and the movement (stroke) of the working piston in the orthogonal direction is allowed.
[0004]
[Problems to be solved by the invention]
By the way, in order to raise the rigidity as a bearing, the flexure bearing usually adopts a configuration of a laminated flexure bearing group in which a plurality of flexure bearings are laminated. When a plurality of flexure bearings are fixed to the outer peripheral edge and the central portion and assembled into a laminated form, the flexure bearings are conventionally separate and can rotate relatively. These phases are likely to be uneven, and stress is generated by a fixing force acting during assembly, and a large stress is applied only to some flexure bearings, which may cause premature breakage.
[0005]
Accordingly, an object of the present invention is to provide a linear motor having a laminated flexure bearing group as a support device for a mover, in which the individual flexure bearings constituting the laminated flexure bearing group are securely assembled in phase. It is to improve durability as a bearing.
[0006]
[Means for Solving the Problems]
The present invention includes a housing and a shaft which is fixed to the movable element of the linear motor, laminated flexure bearing groups central portion outer peripheral portion is fixed to the stator is fixed to the shaft with a stator of the linear motor And a linear motor having
The laminated flexure bearing group is a disc-shaped outer peripheral portion having a central portion having a fixed central hole that is inserted and fixed to the shaft at the center and a plurality of fixed outer peripheral holes that are inserted and fixed to the stator. A plurality of flexure bearings that are between the central portion and the outer peripheral edge portion and spirally extend from the central portion to the outer peripheral edge portion and are laminated in the axial direction, and a plurality of the flexure bearings. It is characterized by comprising a fixing member that fixes the kushisha bearings in advance at the same phase so that they cannot rotate relative to each other .
[0007]
In the linear motor according to the present invention, the flexure bearing has a plurality of central through holes around the fixed central hole in the central portion and a plurality of outer edge through holes in the outer peripheral edge, The fixing member may be constituted by a plurality of fastening bolts that are inserted through the respective central portion through holes and the respective outer edge portion through holes to fix the plurality of flexure bearings .
[0008]
[Operation and effect of the invention]
In Furekushi catcher Bearings of the linear motor according to the present invention, since the pre-individual flexure bearings each other in built before the stage of the linear motor is non-rotatably secured in the same phase by the fixing member, when built The phase is not shifted by the pressing force or rotational force of the bolts and nuts, and there is no possibility of stress acting on some flexure bearings during assembly. For this reason, the problem that some flexure bearings are damaged early can be solved.
[0009]
Further, in the case where the linear motor of the present invention is configured as a piston driving device for a compressor, a non-contact state between the piston and the cylinder can be ensured for a long time.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. FIG. 1 shows a linear motor employed in a drive unit for a direct acting compressor. The compressor 10 is connected to the expander 20 by a connecting pipe, and constitutes a split type Stirling refrigerator together with the expander 20.
[0011]
The compressor 10 is a two-cylinder-facing type, and a housing 10a constituting the compressor 10 is positioned between the pair of left and right storage chambers 11a and 11b and the storage chambers 11a and 11b. , 11b, and a cylinder motor 11b communicating with each of the chambers 11a, 11b. A linear motor 10b is accommodated in each of the accommodating chambers 11a, 11b.
[0012]
The linear motor 10 a includes a yoke 12 and a magnet 13 as a stator, in which includes a bobbin 14 and coil 15 as the movable element, the yoke 12 accommodating chamber 11a, is fixed by being fitted into the 11b Yes. The magnet 13 is fixed to the inner peripheral side of the outer cylindrical portion 12 a of the yoke 12. The bobbin 14 is provided integrally with the operating piston 16, and a coil 15 is wound around the outer periphery of the bobbin 14.
[0013]
The operating piston 16 includes a shaft portion 16a, a piston portion 16b protruding from the tip of the shaft portion 16a, and a cylindrical flange portion 16c extending from the intermediate portion of the shaft portion 16a to the outer peripheral side and the piston portion 16b side. The bobbin 14 is integrally formed at the tip of the portion 16c.
The working piston 16 is inserted into the inner hole 12c of the inner cylindrical portion 12b of the yoke 12, the end of the shaft portion 16a protrudes from the inner cylindrical portion 12b, and the flange portion 16c is fitted to the outer periphery of the inner cylindrical portion 12b. In addition, the piston portion 16b is fitted into the cylinder portion 11c for a predetermined length. Operating piston 16, at one end and the other end of the shaft portion 16a in this state is supported by the outer tubular section 12a of the yoke 12 via the laminated Furekushi catcher Bearings group 17.
[0014]
Laminated Furekushi catcher Bearings group 17, together are fixed to the yoke 12 at the outer peripheral portion, middle and is fixed to the shaft portion 16a of the actuation piston 16 at a fixed central hole, in this state, as described below Further, the center side can be displaced in the orthogonal direction, and the working piston 16 is supported so as to be movable in the axial direction with respect to the yoke 12. Thus, laminated Furekushi catcher Bearings group 17, outer and magnet with which the coil 15 is positioned to face the magnet 13 at the outer peripheral side of the inner tubular portion 12b of the yoke 12, coil 15 and the inner tube portion 12b A predetermined gap is ensured between the inner circumference of 13.
[0015]
The piston portion 16b of the working piston 16 forms a compression chamber R1 in the cylinder portion 11c with the piston portions 16b facing each other, and each piston portion 16b and the cylinder portion 11c are in a non-contact state and are not in contact with each other. A seal is employed to prevent wear of the piston portion 16b and the cylinder portion 11c.
In the linear motor 10b generates a thrust by energizing the alternating current to the coil 15 in the magnetic circuit formed by the yoke 12 and the magnet 13, and drives the operating piston 16 by the thrust, the Furekushi catcher Bearings 17 is moved forward and backward in the axial direction. Thereby, when the linear motor 10 b is driven, the gas in the compression chamber R 1 in the cylinder portion 11 c is compressed, and the compressed gas is sent to the expander 20 through the connecting pipe 18.
[0016]
The expander 20 is formed by integrating a linear motor 20b, which is a driving device, with a housing 20a. The housing 20a includes a storage chamber 21a and a cylinder portion 21b, and an operation piston 22 is interposed in the storage chamber 21a via a compression spring 21c. Is contained. The operating piston 22 includes a shaft portion 22a, a piston portion 22b protruding from the tip of the shaft portion 22a, and a flange portion 22c extending from the outer peripheral side to the tip side at the rear end portion of the shaft portion 22a. A regenerator 23 is included at the tip. In the working piston 22, the piston 22a is inserted into the cylinder 21b in a state where the flange 22c is accommodated in the accommodating chamber 21a, and the regenerator 23 protrudes from the tip of the housing 20a.
[0017]
The linear motor 20 b includes a yoke 24, a magnet 25, a bobbin 26, and a coil 27. The yoke 24 is formed integrally with the housing 20a, and includes an outer cylindrical portion 24a and an inner cylindrical portion 24b positioned concentrically therewith, and a magnet 25 is fixed to the outer peripheral side of the inner cylindrical portion 24b. Yes. The bobbin 26 is integrally provided at the tip of the flange portion 22 c of the working piston 22, and a coil 27 is wound around the outer periphery of the bobbin 26. The coil 27 is located between the outer cylindrical portion 24a of the yoke 24 and the magnet 25 in a state in which the working piston 22 is accommodated in the accommodating chamber 21a, and holds a slight gap between the both 24a and 25. Opposite.
[0018]
The linear motor 20b drives the operating piston 22 to move forward and backward, detects the position of each operating piston of the compressor 10 and the expander 20 with a sensor, and drives based on this detection signal to drive each operating piston. By controlling the advance and retreat of the Stirling refrigerator, the optimum operating state of the Stirling refrigerator can be secured.
The regenerator 23 temporarily stores cold heat in the process where the low-temperature gas in the expansion chamber R2 flows out to the compression chamber R1, and conversely pre-cools this high-temperature gas in the process where high-temperature gas flows from the compression chamber R1. Then, the infrared element or the like attached to the tip of the expander 20 is cooled with the low temperature gas in the expansion chamber R2.
[0019]
Thus, the laminated flexure bearing group 17 that supports the piston portion 16b side of the operating piston 16 has a disc shape in which the disc-like plate spring members 171 are used as individual flexure bearings and the plate spring members 171 are laminated. Is. The individual elements constituting the laminated flexure bearing group 17 have the following shapes.
The leaf spring member 171 is formed with a fixed center hole 171a at the center, and two kinds of through holes 171b1 and 171b2 are alternately formed at the outer peripheral edge portion, and the center portion and the outer peripheral edge portion around the fixed central hole are formed. Three slits 171c extending in a spiral shape from the inner center to the outer periphery are formed in the ring-shaped portion between them. The through hole 171b1 is for fixing the laminated flexure bearing group 17, and the through hole 171b2 through which the fixing member of the present invention is inserted is for fixing the laminated flexure bearing group 17 to the outer cylindrical portion 12a of the yoke 12. This corresponds to the fixed outer peripheral hole of the present invention . A predetermined number of through holes 171d are formed around the fixed center hole 171a. The fixing member of the present invention is also inserted through these through holes 171d . An inner circumferential spacer 172 and an outer circumferential spacer 173 are interposed in the center portion and the outer peripheral edge portion of the leaf spring member 171, respectively. As shown in FIG. 6, the inner circumferential spacer 172 interposed in the center has a through hole 172a that matches the fixed central hole 171a and a through hole 172b that matches the through hole 171d. Has through holes corresponding to the through holes 171b1 and 171b2. Inner circumferential side pressing plates 174 are disposed at both outer positions of the central portion 17a of the laminated flexure bearing group 17 (the central laminated portion of the leaf spring member). One of the inner peripheral side presser plates 174 has a through hole 174b slightly larger than the fixed center hole 171a and a screw hole corresponding to the through hole 171d of the leaf spring member 171, and the other inner peripheral side presser plate 174 has the through hole. It has a through hole that corresponds to 171d and a through hole 174a that matches the fixed center hole 171a. Similarly, outer circumferential side pressing plates 175 are disposed at both outer positions of the outer peripheral edge portion 17 b of the laminated flexure bearing 17. One of the outer peripheral side pressing plates 175 has a through hole that matches the through hole 171b2 of the leaf spring member 171 and a screw hole corresponding to the through hole 171b1, and the other outer peripheral side pressing plate 175 matches the through holes 171b1 and 171b2. It has a through hole.
[0020]
Laminated flexure bearing group 17 is aligned phase slits 171c of the leaf spring member 171, a binding bolt 176 outer peripheral portion 17b (the outer peripheral edge portion laminated portion of the plate spring member) constituting the fixing member of the present invention, through A through hole 172b coinciding with the hole 171d is fixed by a coupling bolt 178 constituting the coupling member of the present invention . The coupling bolt 176 passes through the through holes 171b1 and the spacers 173 alternately from the outer periphery side pressing plate 175 of the first tightening, and is fastened to the screw hole of the outer tightening side pressing plate 175 of the rear tightening. The fastening bolt 177 is inserted into the through hole 171b2 in a state of being fixed by the coupling bolt 176 (FIG. 2), and is fixed to the outer cylindrical portion 12a of the yoke 12.
[0021]
In addition, the coupling bolt 178 corresponding to the fixing member of the present invention for fixing the through hole 174b of the laminated flexure bearing group 17 is connected to the through hole 171d and the spacer 172 from the inner periphery side pressing plate 174 of the tightening of the through hole 174b . The through holes are alternately passed through, and are fastened to the screw holes of the rear tightening inner circumferential side presser plate 174. Thereby, it will be in the state by which each flexure bearing was made immovable (FIG. 4). At the time of incorporation into the linear motor, the shaft portion 16a is inserted through the fixed center hole 171a. As shown in FIG. 2, the laminated flexure bearing group 17 through which the shaft portion 16a is inserted has its axial position restricted by a flanged contact shoulder portion 16a1 of the shaft portion 16a. That is, the through-hole 174b of the rear tightening inner peripheral side presser plate 174 is fitted to the outer periphery of the contact shoulder 16a1, and the central portion of the leaf spring member 171 adjacent to the rear tightener inner peripheral side presser plate 174 is the contact shoulder. It contacts the part 16a1. A projecting portion 16a2 having a fixing screw portion 16a3 protrudes from the abutting shoulder portion 16a1, and the laminated flexure bearing group 17 corresponds to the corresponding shoulder portion by the pressing force of a nut 179 fastened to the fixing screw portion 16a3. 16a1 is pressed.
[0022]
By the way, the spacer 180 which comprises the piston part 16b is interposed between the press plate 174 and the nut 179 on the opposite side of the back tightening inner periphery side press plate 174. The spacer 180 includes a cylindrical head portion serving as the piston portion 16b and a shaft portion that is integral with the head portion and has a fitting hole, and the protruding portion 16a2 is inserted into the fitting hole of the shaft portion. The fixing screw portion 16a3 of the protruding portion 16a2 protrudes into the cavity in the head, and the nut 179 is fastened.
[0023]
9 and 10 show a laminated flexure bearing group 19 in a linear motor as a comparative example. In this laminated flexure bearing group 19, an outer peripheral edge portion 19b and a central portion 19a are common to each other. It is only fixed to the bolt 191 and the shaft portion 16a by the pressing force of the nut 192.
In such a configuration, when the bolt 191 and the nut 192 are fixed, the spacer, the presser plate, and the flexure bearing are relatively easy to move with each other, the position fixed by the presser plate is shifted, and the phase of each flexure bearing is shifted. It doesn't match and is prone to early breakage.
[0024]
However, in the laminated Furekushi catcher Bearings group 17 of the linear motor according to the present invention, before the outer circumferential edge portion 17b is fixed to the yoke 12, the outer peripheral portion 17b is joined by bolts 176, and a center portion 17a Are coupled by a coupling bolt 174. Accordingly, the spacers 172 and 173, the presser plates 175 and 174, and the flexure bearings are kept stationary. Be pressed while turning the fastening bolt 177 and nut 179 laminated Furekushi catcher Bearings group 17 in this state, the phase shift and the spacer of flexure bearings, positional deviation of the pressing plate is none. For this reason, it is possible to reliably avoid a phenomenon in which a load is evenly applied to each flexure bearing and the load is biased to a part of the flexure bearings and is damaged early.
[0025]
The laminated flexure bearing group 17 of the above embodiment is assembled separately from the linear motor. A jig is prepared for this purpose. The jig has a shaft portion having the same diameter as the shaft portion 16 a of the linear motor and an outer cylindrical portion 12 a of the yoke 12. The outer tubular section of the jig may only set a protrusion corresponding to the position of the coupling bolt 176. The rear fastening presser plate 174 is fitted to the contact shoulder portion of the jig shaft portion, and the outer peripheral side presser plate 175 is fitted to the protrusion. Subsequently, the jig shaft portion is fitted in the order of the leaf spring member 171 and the inner circumferential spacer 172, and the outer circumferential spacer 173 is fitted to the protrusion. Thereafter, they are fitted in the same order, but at this time, the phases of the leaf spring members 171 are made the same. When the last presser plates 174 and 175 have been fitted, the central portion 174b is fixed with the connecting bolt 178, and the laminated flexure bearing group 17 before fixing the outer peripheral edge portion 174a is removed from the jig to remove the outer peripheral edge. The part 174a is fixed with the connecting bolt 176. Thus, the laminated flexure bearing group 17 of the present invention is manufactured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a linear motor according to an example of the present invention.
FIG. 2 is an enlarged cross-sectional view of a laminated flexure bearing group that supports a mover of the linear motor.
FIG. 3 is a front view of the same laminated flexure bearing group.
FIG. 4 is a cross-sectional view showing a laminated flexure bearing group before being incorporated into the linear motor.
FIG. 5 is a front view showing one element of the same laminated flexure bearing group.
FIG. 6 is a front view of a spacer interposed in the central portion of the same laminated flexure bearing group.
FIG. 7 is a cross-sectional view showing another example of the same laminated flexure bearing group.
FIG. 8 is a cross-sectional view showing still another example of the same laminated flexure bearing group.
FIG. 9 is a cross-sectional view of a comparative example of a laminated flexure bearing group.
FIG. 10 is a front view of a laminated flexure bearing group according to a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Compressor, 10a ... Housing, 10b ... Linear motor, 11a, 11b ... Accommodating chamber, 11c ... Cylinder part, 12 ... Yoke (stator), 12a ... Outer cylinder part, 12b ... Inner cylinder part, 12c ... Inner hole , 12d ... projecting portion, 13 ... magnet, 14 ... bobbin, 15 ... coil, 16 ... working piston (movable element), 16a ... shaft portion, 16a1 ... contact shoulder portion, 16a3 ... contact shoulder portion, 16b ... piston portion , 16c ... flange portion, 17 ... laminated flexure bearing, 17a ... central portion, 17b ... outer peripheral edge portion, 18 ... connecting pipe, 20 ... expansion machine, 20a ... housing, 20b ... linear motor, 21a ... accommodation chamber, 21b ... Cylinder part, 21c ... compression spring, 22 ... working piston, 22a ... shaft part, 22b ... piston part, 22c ... flange part, 23 ... regenerator, 24 ... yoke, 24 ... outer cylinder part, 24b ... inner cylinder part, 25 ... magnet, 26 ... bobbin, 27 ... coil, compression chamber R1, R2 ... expansion chamber, 171 ... leaf spring member, 171c ... slit, 172 ... inner circumferential side spacer, 173 ... outer periphery side spacer, 174 ... inner periphery side pressing plate, 175 ... outer periphery side pressing plate, 176 ... coupling bolt, 177 ... fastening bolt, 178 ... coupling bolt.

Claims (2)

Having a housing with a stator of a linear motor, a shaft fixed to the movable element of the linear motor, a laminated flexure bearing groups central portion outer peripheral portion is fixed to the stator is fixed to the shaft, the A linear motor,
The laminated flexure bearing group has a disk-like central portion having a fixed center hole that is inserted and fixed to the shaft in the center , an outer peripheral portion having a fixed outer peripheral hole that is inserted and fixed to the stator , and A plurality of flexure bearings that are disposed between the central portion and the outer peripheral edge portion and have a plurality of slits spirally extending from the central portion to the outer peripheral edge portion, and stacked in the axial direction; and a plurality of the flexures A linear motor comprising a fixing member that fixes bearings in advance in the same phase so that they cannot be rotated relative to each other . The flexure bearing has a plurality of central through holes around the fixed central hole in the central portion, and a plurality of outer edge through holes in the outer peripheral edge, and the fixing member has each central through hole. The linear motor according to claim 1, further comprising a plurality of fastening bolts that are inserted through the outer edge portion through holes and fix the plurality of flexure bearings .

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