GB2227529A

GB2227529A - Rotary structure

Info

Publication number: GB2227529A
Application number: GB9001215A
Authority: GB
Inventors: Tsutomu Nakanishi
Original assignee: CSU Ltd; C S U Ltd
Current assignee: CSU Ltd; C S U Ltd
Priority date: 1986-01-28
Filing date: 1990-01-19
Publication date: 1990-08-01
Anticipated expiration: 2007-01-21
Also published as: GB9001215D0; GB2227529B

Description

ROTARY STRUCTURE A swindle unit used for a miniature motor or miniature rotor has been conventionally formed as shown in Fig. 22.

That is to say, a pair of radial ball bearings 21 and 22 are arranged in the upper and lower parts of the outer periphery of a shaft 20, a cylindrical spacer 23 is arranged between the outer races 21a and 22a of these radial ball bearings 21 and 22 to position the radial ball bearings 21 and 22 with each other, these are fixed with the hole H of a bearing using 24, suc rotor 25 as a tuley, disc cr turntable is fixed to the end of the shaft 20 and the shaft 20 side is rotated.

The rotary mechanism of such roller as a conventional tae guide roller has been formed also substantially the same.

oever, in the above mentioned formation, in order to prevent dust or the like from entering the radial ball bearings 21 and 22 and reducing the performance, a so-called double sealing structure wherein sealing members S are arranged on both sides of balls 21c or 22c provided within each of the radial ball bearings 21 and 22 is used in the rotary mechanism.

There have been defects that the radial ball bearings 21 and 22 have many component parts, are complicated to assemble and are high in the cost.

There has been also a defect that the clearances (in four places) of the radial ball bearings 21 and 22 swing the shaft 20 in the rotation.

This invention is suggested to solve the above mentioned defects and has it as an object to provide a rotary structure wherein the formation of radial ball bearing parts is slmFlified, manufacturing and assembling works are =aae easy and the cost is reduced.

Another obec of the Present invention is to provide a rotary structure wherein the inner race and shaft are made integral so as to be small and light, to make the bal diameter larger than before and to improve the rigidity.

Purtee-, another object of the present invention is to provide a rotary structure wherein, by finely adjusting the position of the outer race in assembling, the clearance can be easily adjusted and the precision can be improved.

Brief Description of the Drawings: Fig. 1 is a schematic vertically sectioned view of the first embodiment of the present invention.

Fig. 2 is of the second embodiment of the present invention.

Fig. 3 is of the third embodiment of the present invention.

Fig. 4 is of the fourth embodiment of the present invention.

Fig. 5 is of the fifth embodiment of the present invention.

Fig. 6 is of the sixth embodiment of the present invention.

Fig. 7 is of the seventh embodiment of the present invention.

Fig. 8 is of the eighth embodiment of the present invention.

Fig. 9 is of the ninth embodiment of the present invention.

Fig. 10 is of the tenth embodiment of the present invention.

Fig. 11 is of the eleventh embodiment of the present invention.

wigs. 12(1) to (4) are exr,;natory vews showing the twelfth embodiment of the present invention as being assembled.

Fig. 13(a) is of the thirteenth embodiment of the present invention and Fig. 13(b) is an explanatory plan view showing balls as held at intervals by a sleeve.

Fig. 14(a) is of the fourteenth embodiment of the present invention and Fig. 14(b) is an explanatory plan view showing balls as held at intervals by a retainer.

Fig. 15 is of the fifteenth embodiment of the present invention.

Fig. 16(a) is an explanatory plan view showing balls as incorporated in a retainer and provided around a shaft and Fig. 16(b) is a sectioned view on line A-d in Fig. 16(a).

Figs. 17 and 18 show respectively other modes of a retainer.

Figs. 19(1) and (2) are explanatory views showing the fifteenth embodiment as being assembled.

Fig. 20 is of the sixteenth embodiment of the present invention.

Figs. 21(1) to (3) are explanatory views showing the sixteenth embodiment as being assembled.

Fig. 22 is of a prior art example.

In Fig. 1 showing the first embodiment of the present invention, grooves la of a semicircular crosssection for receiving balls 2 are formed as separated from each other respectively in the upper part and lower part on the outer periphery of a columnar shaft 1 by cutting or grinding over the entire periphery and a proper number of balls 2 are rotatably received in each of these grooves la. The respective balls 2 are rotatabby borne by substantially cylindrical outer races 3 provided around the outer periphery of the shaft 1.

That is to say, a concave spherical ball receiving surface 3a of a radius of curvature somewhat larger than of the groove la is formed at the inner end of the outer race 3 and the balls 2 are provided between thiC ball receiving surface 3a and the groove 1a, The outer perpheral surface ib Ol the shaft 1 and the inner peripheral surface 3a of the outer race 3 opposed thereto are in no contact with each other to form a dust preventing clearance g and a cylindrical sleeve 5 is provided between the pair of outer races 3 sepa- rated from each other.This sleeve 5 is to prevent the balls 2 from dropping in assembling, is fixed to the inner peripheral surface of a bearing housing 4, has the respective outer ends Positioned near the bay 2 and is in no contact with the outer races 3, balls 2 and shaft 1. By the way, in some case, the sleeve 5 may be attached to the shaft 1 side. The respective outer races 3 are also fixed to the inner peripheral surface of the bearing housing 4.

In case this assembly is to be used for a miniature motor or miniature rotor, a pulley 7 may be provided in the lower part of the shaft and such rotor 6 as a pulley, disc, turntable or drum may be provided in the upper part of the shaft 1 to form a rotary structure.

In assembling, first of all, the sleeve 5 is fixed as by pressing in substantially in the middle of the hole of the bearing housing 4 and the shaft 1 is inserted into the sleeve 5. Then a proper number of balls 2 on the upper or lower side are Dut into the corresponding ball 2 receiving groove la and grease or oil is poured into that part. Then, the outer race 3 to be positioned on the opening side of the hole is put into the hole of the bearing housing 4 from the opening to press the balls 2 with the ball receiving surface 3a and is fixed in a proper position on the inner peripheral surface of the bearing housing 4.

Then, the balls 2 and outer race 3 on the other side may be put in in the same manner and, as required, the upper rotor 6 and lower pulley 7 may be fixed to the respective ends of the shaft 1.

By the way, in the above mentioned assembling step, before the upper rotor 6 and lower pulley 7 are fixed, the rotating precision of the bearing housing 4 can be confirmed and, by finely adjusting the position of the outer race 3, the clearance from the balls 2 can be easily adjusted and a favorable rotation performance can be obtained.

By the way, the inner peripheral surface 3b of the outer race 3 is so close to the outer peripheral surface 1b of the shaft 1 that, by the dust preventing clearance g of this fine gap, the entry of dust or the like into the ball part can be prevented bo be minimum.

Fig. 2 is of the second embodiment of the present invention. This embodiment is different from the first embodiment in respect that the shaft 1 is made the fixed side and the bearing housing 4 is formed of a cylindrical member and is made rotatable so as to be able to be used, for example, as a tape guide roller.

By the way, flanges 6A and 7A are provided respectively in the upper part and lower part of the shaft 1. The other formations are the same as in the first embodiment, therefore, the same members shall be represented by the same reference numerals and no detailed erclana- tion shall be made.

Fig. 3 shows the third embodiment of the present invention. This embodiment has features in respect that the outer race 3 is not fixed but is made slidable on the inner peripheral surface of the bearing housing 4 and is fixed by an outer race presser 8 provided outside the outer race 3 and fixed to the inner peripheral surface of the bearing housing 4 and, in such case, both or either one of the upper and lower outer race pressers 8 is made of such elastic member as of rubber so as to give a pre-pressure to the outer race 3 in contact with the balls 2 and to prevent a backlash from being caused by the abrasion of the ball rolling surface.

The other formations are the same as in the first and second embodiments.

Fig. 4 shows the fourth embodiment of the present invention. In this embodiment, such resilient member as a spring 9 is provided as contracted between the outer race 3 and outer race presser 8 so as to give a pre-pressure to the outer race 3.

Fig. 5 shows the fifth embodiment of the present invention. In this embodiment, either one of the outer race dressers is made of an outer race at dust ing screw 8A structure, a screw part 4a to be screwed with that screw part is formed on the inner peripheral surface of the bearing housing 4 so that the position of the outer race 3 may be adjusted by the outer race adjusting screw 8A for adjusting the clearance to adjust the clearance between the balls 2 and outer race 3. By the way, the other outer race presser 8 is to be fixed to the bearing housing 4.

Fig. 6 shows the sixth embodiment of the present invention. In the first to fifth embodiments, two ball parts are provided but, in the subsequent embodiments, one ball Fart is shown to be provided only one one side.

That is to say, a groove 1a is formed in a part on the outer periphery of the columnar shaft 1 and the balls 2 are held by this groove la and a ball receiving surface 3a of the outer race 3 fized to the inner peripheral surface of the bearing housing 4.

By the way, a short cylindrical sleeve 5 to be fixed to the inner peripheral surface of the bearing housing 4 is provided near the balls 2 and the ball receiving surface 3a of the outer race 3. A dust preventing clearance g is formed between the inner peripheral surfaces of the outer race 3 and sleeve 5 and the outer peripheral surface of the shaft 1.

In assembling, the sleeve 5 is fixed within the bearing housing 4, then the shaft 1 is inserted into the sleeve 5 and a proper number of the balls 2 are put in from the other opening side and are positioned within the groove la. In such case, the balls 2 are prevented by the sleeve 5 from dropping. Then, the outer race 3 may be put into the bearing housing 4 and may be fixed in a proper position. By the way, as required, the other part of the shaft 1 may be borne by an ordinary radial ball bearing, plane bearing or pivot bearing.

Fig. 7 shows the seventh embodiment of the present invention. This embodiment is different from the sixth embodiment in respect that a sleeve 4' extending toward the shaft 1 is integrally formed on the inner peripheral surface of the end part of the bearing housing 4. The other formations are the same.

Fig. 8 shows the eighth embodiment of the present invention. in this embodiment, the outer race 3 in the sixth embodiment is loosely fitted within the bearing housing 4 and is fixed by the outer race presser 8 made of an elastic member and arranged outside the outer race 3 so as to give a pre-pressure by the elasticity of the outer race presser 8 and to prevent a backlash from being caused by the abrasion of the ball rolling surface. The other formations are the same as in the sixth embodiment.

Fig. 9 shows the ninth embodiment of the present invention. This embodiment is different from the eighth embodiment in respect that the outer end of the outer race 3 loosely fitted within the bearing housing 4 and the inner end of the outer race presser 8 to be fixed within the bearing housing 4 are separated from each other and such resilient member 9 as a spring is provided as contracted between them so as to give a pre-pressure to the outer race 3. It is needless to say that, in such case, the outer race presser 8 is not specifically required to be of an elastic member.

Fig. 1G is of the tenth embodiment of the present invention. In this embodiment, the outer race adjusting acrew 8s is provided outside the outer race 3 and on the inner peripheral surface of the bearing housing 4 so as to make it possible to adjust the clearance..

Fig. 11 shows the eleventh embodiment of the present invention. In the case that the ball receiving concave spherical part 3a shown in the above described respective drawings is to be formed in the outer race 3, if the outer race 3 is ground by using an existing grinding machine, generally the outer race 3 will be displaced by the grinding resistance and will not be able to be ground as expected.

Therefore, in this embodiment, the outer race 3 is somewhat extended at the lower end so as to be easy to grind. That is to say, the length to the broken line a is of the ball receiving part 3a of the outer race 3 of the above described respective embodiments. This ball receiving surface 3a is of a concave spherical surface partly cut off, whereas, in this embodiment, the ball receiving surface 3a is further extended at the lower end so as to be of a shape rather close to a concave spherical surface.

In such case, the outer race 3 is to be fitted around the balls 2 provided on the outer periphery of the groove 1a of the shaft 1 by applying a small force in assembling and is extended at the lower end so as not to obstruct the incorporation.

It is needless to say that, in case the incorporation is obstructed, the obstrcig part may be cut off and removed and the ball receiving surface 3a of the above described respective embodiments may be made.

This embodiment can be applied to the first to tenth embodiments and the later described embodiments.

3y the way, it is preferable that, in case the contact points E and D of the ball 2 respectively with the shaft 1 and outer race 3 are on the straight line passing through the center of the ball 2, the ball 2 will not contact with the shaft 1 in the part C between them and will contact with the shaft 1 and outer race 3 respectively at one point.

Fig. 12 shows the twelfth embodiment of the present invention. In this embodiment, the distance between the pair of grooves 1a formed on the outer periphery of the shaft 1 is short and the sleeve for preventing the balls from dropping is not required so that the assembling parts may be decreased and the assemblability may be improved.

That is to say, in assembling, as shown in Fig. 12(1), first the shaft 1 is inserted into a hollow part provided with one outer race 3 at one end of the bearing housing 4 and is arranged in a proper position.

Then, in the illustrated state, a proper number of the balls 2 are inserted from the lower side. in this case, a ball receiving jig 6' is used to prevent the balls 2 from dropping. The balls 2 will be supported by the rolling surfaces of the groove la and the ball receiving surface 3a of the outer race. By the way, the outer race 3 is to be fixed in a position of favorably holding the balls 2. Then, as shown in Fig. 20(2), the above mentioned assembly is turned upside down and a proper number of balls 2' are intered be'wee^. the bearing housing 4 and shaft 1 from the upper side.

Then, as shown in Fig. 12(3), the other outer race 3' is inserted into the bearing housing 4 and, as shown in Fig. 12(4), the balls 2' are supported by the ball receiving surface 3a' of this outer race 3' and the groove 1a' and the outer race 3' is fixed in a proper position so that a light, thin and short spindle unit may be assembled. That is to say, in the spindle unit of this invention, the distance between the grooves la and la' is short, no sleeve is required, the weight is reduced, the balls 2 and 2' are held directly by the shaft 1 and the outer races 3 and 3' provided on the outer periphery of the shaft 1 and therefore the type is thin.

By the way, in using, the inner peripheral surfaces 3b and 3b' of the outer races 3 and 3' are so close to the outer periphery 1b of the shaft 1 that the entry of dust or the like into the ball parts can be prevented by the dust preventing clearance g of this fine gap to be minimum. See Fig. 12(4). It is needless to say that this embodiment may be used not only as a spindle unit but also as a roller.

Figs. 13(a) to (d) show the thirteenth embodiment of the present invention. In the rotary structure in each cf the above described embodiments, the sals 2 are held by the groove la of a semicircular crosssection formed on the outer periphery of the shaft 1 and the ball receiving surface 3a of the outer race 3 provided within the bearing housing 4, the dust preventing clearance g is formed between the inner peripheral surface 3b of the outer race 3 and the outer peripheral surface ib of the shaft 1 and the sleeve 5 is provided within the bearing housing 4 to prevent the balls 2 from dropping in assembling so that the cost may be reduced, the number of component parts may be decreased, the shape may be simplified, the assembly may be made easy, the size may be made small, the weight may be made light and the performance may be practically sufficient.

However, in the rotary structure of the above mentioned formation, the balls 2 arranged around the shaft 1 are generally intended to be full balls and, in such case, there are problems that, above the medium speed rotation, the balls will collide with one another to make a noise and mechanical loss.

Therefore, in this thirteenth embodiment, the noise generation and mechanical loss are reduced.

That is to say, this embodiment is characterized in that a means of holding the balls at proper intervals with each other is provided so that the bails may be separated from each other and may not collide with each other, the noise generation and mechanical loss may be controlled to be minimum and the sleeve 5 is made to have a function as of a retainer.

This sleeve 5 can be formed of such resin as, for example, Delulin, has a function as of a retainer holding the balls 2, has a required number of semicircular grooves 5a having a play larger than the ball 2 formed to correspond to the number of tne balls at proper intervals and has the balls 2 received in the respective grooves 5a and held at proper intervals as separated from each other.

In assembling, first of all, the sleeve 5 is fixed as by pressing substantially in the middle within the bearing housing 4 and the shaft 1 is inserted into the sleeve 5. Then, a proper number of the balls 2 on the upper or lower side are put into the corresponding grooves 5a and are received by the ball receiving groove la of the shaft 1 and grease or oil is poured into that part. Then, the outer race 3 to be positioned on the opening side is put into the bearing housing 4 from the opening to press the balls 2 with the ball receiving surface 3a and is fixed in a proper position on the inner peripheral surface of the bearing housing 4.The bais 2 any outer race 3 on the other side may be put in in the same manner and, in the case of using the rotary structure as a roller, the upper and lower flanges 6A and 7A may be fixed to the respective ends of the shaft 1.

By the way, in the above mentioned assembling step, before the upper and lower flanges 6A and 7A are fixed, the rotation precision of the bearing housing 4 can be confirmed and, by finely adjusting the position of the outer race 3, the clearance from the balls 2 can be easily adjusted and a favorable rotation performance can be obtained. The inner peripheral surface 3b of the outer race 3 is so close to the outer peripheral surface ib of the shaft 1 that, by the dust preventing clearance g of this fine gap, the entry of dust or the like into the ball part can be prevented to be minimum.

By the way, in the above, the sleeve 5 is fixed to the inner peripheral surface of the bearing housing 4 with a bonding agent or by pressing in but may be fixed to the outer peripheral surface of the shaft and separated from the housing 4 to obtain the same function.

By the way, in this embodiment, the sleeve is made to have the function of a retainer, no retainer is separately formed and therefore the cost is that much lower.

wigs. 't(a) d (b) show the fourteenth em.bcdi- ment of the present invention. This embodiment is different from the above described embodiment in respect that a means of holding the balls at proper intervals with each other is formed of a retainer 2A separately from the sleeve 5.

Therefore, the sleeve 5 is merely cylindrical and is provided on the inner peripheral surface of the bearing housing 4 and in no contact with the respective members. By the way, this sleeve 5 is to prevent the balls 2 held by the ring-shaped retainer 2A in assembling from dropping. A retainer 2A escaping part 3c is formed in the outer race 3. The other formations are the same as in the thirteenth embodiment.

In assembling, first of all, a proper number of the balls 2 are put as arranged at intervals into the retainer 2 for example, within a jig (not iliust- rated). Ihis jig is made to have a magnetic force or attraction so that the balls 2 put in may not drop while being assembled.

On the other hand, the sleeve 5 is fixed as by pressing substantially in the middle within the bearing housing 4 and the shaft 1 is inserted into the sleeve 5. Then, some of the balls held at intervals by the retainer 2A on the upper or lower side are partly received in the groove la and grease or oii is poured into that part. Then, the outer race 3 to be positioned on that side is put into the bearing housing 4 from the opening so as to receive and press the bails 2 on the ball receiving surface 3a and is fixed in a proper position on the inner peripheral surface of the bearing housing 4. Then, the balls 2 and outer race 3 on the other side may be put in in the same manner.

Fig. 15 shows the fifteenth embodiment of the present invention. In this embodiment, the sleeve 5 for preventing the balls 2 from dropping in the above described fourteenth embodiment is not required and the assembling is made that much easier.

In this case, the retainer 2A is ring-shaped as shown particularly in Figs. 16(a) and (b) and is made of such resilient member as of a resin or mental.

The balls 2 are held through ball receiving parts provided at proper intervals and, in this case, consisting of holes of a diameter substantially equal to or somewhat smaller than the ball diameter. That is to say, in this retainer 2A, each ball 2 is forcibly put into the hole having such clearance from the ball 2 as prevents the ball 2 from being let out. The other formation of the retainer 2A may be such ordinary one as is shown in Fig. 17 or such as is shown in Fig. 18 wherein te retainer 2 ring is made of C resi;ise member having a cut A made in a part so as to be easily variable in the inside diameter.

In assembling, as shown in Fig. 19(1), the retainer 2A in which the balls 2 are incorporated in advance is pushed onto the outer periphery of the shaft 1. In this case, the retainer 2A will be pushed to expand somewhat outward by the shaft 1 and the balls 2 in contact with the shaft 1. That is to say, the retainer 2A is of a diameter naturally larger than of the shaft 1 but will be pushed to expand somewhat outward in the diameter against the resiliency caused by the material in the case of fitting the balls 2 to the outer periphery of the shaft 1. As shown in Fig.

19(2), when the retainer 2A is pushed on and the balls 2 reach the groove la, the retainer 2A will contract tha much and the balls 2 will be resgectivel itted without dropping. Then, this assembly is inserted into the bearing housing 4 and the outer race 3 is inserted from outside so that such rotary structure as a spindle unit may be assembled without using any sleeve.

In using, the inner peripheral surface 3b of the outer race 3 is so close to the outer peripheral surface ib of the shaft 1 that the entry of dust or the like into the bail part can be prevented by the dust preventin~ ceararce g cf this fine gap so as to be minimum. See Fig. 15.

Fig. 20 shows the sixteenth embodiment of the present invention. This embodiment is characterized in that the distance between the pair of grooves la formed on the outer periphery of the shaft 1 is short and a retainer 2A' is provided with two steps of the balls 2 corresponding to the pair of grooves 1. The basic material and formation of the retainer 2A' are the same as in the above described embodiments.

In assembling, as shown in Fig. 21(1), first of all, the balls 2 incorporated in the retainer 24' are fitted to the outer periphery of the shaft 1 and are pushed toward the ball receiving parts la as indicated by the arrow.

Then, as shown in Fig. 21(2), when the balls 2 located on the lower side in t drawing first reach the groove la on the upper side, The balls 2 wil fit into the groove la due to the resiliency of the retainer 2A'. At this time, the ball part on the upper side will remain pushed to expand outward.

Then, when the balls are further pushed on, as shown in Fig. 21(3), the bails in the two upper and lower steps will respectively fit into the grooves la so as to be fitted to the outer periphery of the shaft 1.

S in the above, according tc the present invention, without using a radial ball bearing, a ball receiving groove of a semicircular cross-section is formed on a shaft, balls are held by the ball rolling surfaces of this groove and the ball receiving surface of an outer race provided on the inner peripheral surface of a bearing housing, no expensive radial ball bearing of a double sealing structure is required and the cost can be that much reduced.

The minimum component parts around the shaft may be the balls, outer race, sleeve provided as required and bearing housing and the component parts are decreased in the number to be fewer than before and are simple in the shapes, easy to make, low in the cost and easy to assemble.

The balls are partly contained in the ball receiving groove on the shaft, therefore the type can be made small and the number of the component parts is so small that the weight can be reduced.

In case the contour is the same as in the past, the ball diameter can be made that much larger and therefore the rigidity can be improved.

In the conventional radial ball bearing, in order to make the clearance between the inner race and outer race have a width, the dimensions of the outside diameter of the inner race and the inside diameter of the outer race had to be measured so as to be combined by keeping a proper clearance with respect to the diameter of the balls but, in the present invention, such complicacy is unnecessary, if the position of incorporating the outer race is displaced, the diameter of the balls can be made somewhat larger and, in this respect, too, the rigidity can be improved.

Further, in assembling, by finely adjusting the position of the outer race, the clearance can be freely and easily adjusted.

Claims

1. A rotary structure characterized by comprizing a columnar shaft having a groove of a semicircular crosssection for partly receiving balls on the outer periphery, an outer race provided on the outer periphery of said shaft, having a ball receiving concave spherical surface formed to be in contact with said bails and holding the balls together with said groove and a bearing housing having said outer race fixed on the inner peripheral surface.

2. A rotatable shaft and bearing device comprising a shaft having an annular peripheral groove of substantially semicircular cross-section. an annular bearing race surrounding said shaft and having an inner surface having a concave curved profile. .:lda 3 plurality of balls engaging said groove and said inner surface to provide a rotary bearing for the shaft

3. A rotary structure substantially as herein described with reference to any of Figures 1 - 21 of the accompanying drawings.

Amendments to the claims have been filed as follows 1. A rotary structure comprising, a housing having a through-hole, a columnar shaft extending through the through-hole and having at least one circumferential groove, of semi-circular cross-section, formed in the periphery thereof, an outer ball race having a concave, ball-receiving surface for locating a plurality of balls in the groove with a predetermined pressure, and a retainer for holding the balls apart from each other in the groove, wherein the retainer comprises a tube which fits around the shaft and is made of a resilient material, the tube being formed with spaced, circumferentially disposed holes, each locating a respective ball.

2. A rotary structure as claimed in claim 1, including a pair of said grooves formed in a surface of the shaft, a respective plurality of balls disposed in each groove, a pair of said outer ball-races for locating the balls of each plurality in a respective groove, and wherein the retainer holds the balls of each plurality apart from each other in the respective groove.

3. A rotary structure as claimed in claim 2, wherein the retainer is a common retainer for holding the balls of each said plurality apart from each other in the respective groove.

4. A rotary structure unit as claimed in any one of claims 1 to 3, wherein the tube has a slit along its length.

5. A rotary structure substantially as hereinbefore described with reference to the accompanying drawings.