JP2007247703A - Bearing and method for bearing shaft of rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing and a method for bearing a shaft of a rotor, which are adaptable for various applications for bearing the shaft of the rotor, reduce weight, and save on a space. <P>SOLUTION: This bearing 200 is provided with a pair of storage parts 206, 208 for storing a plurality of balls 210 each to bear the shaft of the rotor 204 so as to rotate for an annular supporting body 202. In each storage part, a flat section 206 (208) and a curved section 214 (218) extending in the axial direction from the flat section and curved so as to store the ball 210 are annularly formed along the peripheral direction, height of an edge of the flat section is larger than height of the stored ball, and height of an edge of the curved section is smaller than height of the stored ball. The pair of storage parts are fitted into the supporting body 202 while the curved section 214 of the storage part 206 on one side, faces the curved section 218 of the storage part 208 on the other side. The rotor 204 is arranged between a pair of flat sections while it is abutted on the ball and slides on the ball to rotate to the supporting body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing for bearing a rotating body and a bearing method for the rotating body.

  Generally, a bearing is used as a part for bearing a rotating body rotatably with respect to a support. The bearing includes, for example, an inner cylindrical portion 302 where a shaft (not shown) is inserted and fixed, as in a radial ball bearing 300 shown in a side sectional view of FIG. 12, and a radial direction of the inner cylindrical portion 302 An outer cylindrical portion 304 disposed coaxially on the outside, a large number of balls 306 interposed between the concave portions of the inner cylindrical portion 302 and the concave portions of the outer cylindrical portion 304, and a cover that rotatably covers the balls 306 Member 308. The outer cylindrical portion 304 and the inner cylindrical portion 302 are interlocked with low friction via a ball 306 fitted in the concave portion. Thus, by fixing the outer cylinder part 304, the shaft inserted and fixed in the inner cylinder part 302 can be freely rotated. In addition, this configuration can provide good sliding even when a load is applied in the radial direction and the axial direction.

  However, in the above conventional bearing mechanism, for example, when a bearing that is applied to a large-diameter shaft is manufactured, both the solid inner cylindrical portion 302 and the outer cylindrical portion 304 are increased in size, so that the weight is significantly increased. To do. In addition, the bearing mechanism of the prior art has a problem that it cannot be sufficiently adapted to space-saving and a wide variety of spatial and structural arrangements of bearings because there is little freedom to change the shape structurally. .

  The present invention has been made in view of the above-described facts, and an object of the present invention is to provide a bearing and a rotating body bearing method that can be adapted to various types of bearing applications and that achieves weight reduction and space saving.

  In order to solve the above-described problem, a bearing according to an aspect of the present invention is a bearing including a pair of annular accommodating portions that accommodate a plurality of balls in order to rotatably support a rotating body with respect to a support, Each of the pair of receiving portions includes an annular flat section, and a curved section that extends in an axial direction from the flat section and is curved to receive the ball. The flat section and the curved section Forms an annular groove in which a plurality of balls are arranged side by side in the circumferential direction, the height of the edge of the flat section is higher than the height of the accommodated ball, and the height of the edge of the curved section is accommodated The pair of accommodating portions is lower than the height of the ball, and the rotating body is fitted with a pair of flat sections with the curved section of one accommodating section facing the curved section of the other accommodating section. Arranged in contact with the ball between the rotating body , It becomes rotatable relative to the support by sliding on balls.

  Preferably, the annular groove extends over the entire circumference, and the plurality of balls are arranged with a clearance between adjacent balls for sliding freely in the circumferential direction within the annular groove. Preferably, the pair of accommodating portions are press-fitted into the support body. As a result, the assembly of the bearing of the present invention can be facilitated, and the housing portion can be prevented from falling off the support.

  When a radial force is applied to the rotating body of the bearing, the force is transmitted in the order of the peripheral end of the rotating body, the ball, the housing portion, and the support body. Since the radial force can finally be received by the support, the bearing of this aspect can easily withstand the radial load. In addition, since the pair of storage portions are arranged on the support side by side with the pair of curved portions facing each other, the rotating body can be stably supported even if the peripheral end portion is inclined. It becomes. Here, it is preferable that the curved sections of the pair of accommodating portions are in contact with each other. Thereby, since a pair of accommodating part supports each other, while reducing the size of an axial direction, it can prevent the backlash of an accommodating part. Further, the edge of the curved section is at a position lower than the height of the ball accommodated in the curved section, whereby the ball contact surface of the peripheral end portion of the rotating body extends across the pair of accommodating sections. Even with a wide flat portion, the rotating body can be slid on the ball in a stable state without hitting the edge of the curved section. In order to simplify the structure, the pair of accommodating portions may be formed and arranged so as to be mirror-symmetric with respect to each other.

  Preferably, at least one of the pair of flat sections is disposed between the rotating body and the side wall extending from the support. As a result, when a force is applied to the rotating body in the axial direction, the force is divided from the peripheral end portion of the rotating body to the flat section of the housing portion arranged in the direction of the applied force among the pair of housing portions. To the opposite side wall. As described above, since the axial force can be finally received by the side wall, the bearing of this aspect can be configured to easily withstand the axial load. Further, since the flat section is sandwiched, the bearing can be more firmly fixed to the support.

  Preferably, the curved section is formed such that the distance between the edge of the curved section and the flat section is smaller than the diameter of the ball. In this case, the ball may be pressed into the curved section. As a result, the ball can be reliably accommodated in the accommodating portion without fear of falling off, and a stable rotational motion is possible.

  In the bearing of the present invention, the rotating body (inner cylinder part that receives the shaft) is supported as in the normal radial bearing described in the section of the related art, and the mode in which the rotating body is arranged on the outer side in the radial direction of the supporting body. The present invention can be applied to any of the modes arranged on the radially inner side of the (outer cylinder). In the former aspect, the pair of storage portions are configured to be radially inward of the ball in which the bottom portion of the curved section is stored, the rotating body has a central hole, and the pair of storage portions has the curved section. The bottom part of the support body is fitted on the outer side in the radial direction of the support body in a state where it is placed on the outer peripheral wall of the support body, and the rotating body can slide on the ball with the inner peripheral wall of the central hole in contact with the ball Be placed. In the latter aspect, the support has a central hole, and the pair of storage portions is configured to be radially outward from the ball in which the bottom of the curved section is stored. The bottom part of the rotating body is fitted into the central hole of the support body in a state where it is placed on the inner peripheral wall of the central hole of the support body, and the rotating body is placed on the ball with the outer peripheral wall of the rotating body in contact with the ball. Is slidably arranged.

  As described above, the present invention can provide a bearing that can withstand axial and radial loads with a simple configuration in which a ball is housed in a housing portion having a flat section and a curved section. In the configuration of the present invention, for example, since the housing portion can be created by processing only one metal plate, the manufacture of the bearing can be extremely simplified, even if a rotating body having a large diameter is used. Significant weight reduction can be achieved.

Yet another aspect of the present invention relates to a method of bearing a rotating body rotatably with respect to a support. The method includes a pair of accommodating portions that accommodate a plurality of balls, each of the pair of accommodating portions being curved so as to accommodate an annular flat section and an axially extending portion from the flat section. An annular curved section, wherein the flat section and the curved section form an annular groove in which a plurality of balls are arranged in a circumferential direction, and the height of the edge of the flat section is accommodated. Preparing a pair of housing portions that are higher than the height of the balls and the height of the edge of the curved section is lower than the height of the housed balls, and fitting one of the pair of housing portions to the support, The rotating body is placed so as to come into contact with the ball accommodated in the fitted accommodating portion, and the curved section of the other accommodating portion of the pair of accommodating portions faces the curved section of the one accommodating portion. The other accommodating portion is fitted to the support body, whereby the rotating body is connected to the pair of accommodating portions. Are arranged in a state in which balls and in contact between the tongue segment, the rotating body is made rotatable relative to the support by sliding on balls, comprising the steps,
According to this aspect, it is possible to provide a bearing method that can flexibly correspond to an application in which a rotating body of various aspects is rotated on a support. Of course, all the advantages of the bearing according to the above-described aspect of the present invention can be enjoyed. Further, in the case where the rotating body and the support are provided in advance, in this embodiment, a part of them is used as a part of the bearing mechanism, so that weight reduction can be further promoted.

  Other objects and advantages of the present invention will be more clearly understood by referring to the preferred embodiments of the present invention described below.

  A first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the bearing 200 according to the first embodiment of the present invention rotates a ring-shaped rotating body 204 around the same axis S with respect to a disk-shaped annular support body 202 in the direction of the arrow. A pair of annular accommodating portions 206 and 208 for accommodating the ball 210 are provided for bearings as possible. Each of the pair of receiving portions 206, 208 includes an annular flat section 212, 216 and curved sections 214, 218 that extend axially from the flat section and are curved to receive the ball. The pair of housing portions 206 and 208 are fitted to the support 202 in a state where the curved section 214 of one housing portion 206 faces the curved section 218 of the other housing portion 208. In this example, the curved section 214 and the curved section 218 are in contact with each other, and the bottoms of the curved sections 214 and 218 are in contact with the bottom plane of the outer peripheral wall 203 of the support 202.

  Preferably, the pair of accommodating portions 206 and 208 are press-fitted into the support body 202. As a result, the pair of accommodating portions 206 and 208 can be reliably and easily attached to the support 202. In addition, one flat section 216 is disposed between the rotating body 204 and the side wall 207 extending from the support body, and secures the housing portion to the support body.

  Also, the top height of the contained ball 210 is higher than the height of the edges of the curved sections 214, 218. Accordingly, the peripheral end portion 209 of the rotating body 204 can contact the ball 210 without hitting the edge of the curved section. Furthermore, the height of the edge of the flat section is higher than the height of the contained ball. As a result, a part of the rotating body 204 is sandwiched between the pair of flat sections 212 and 216, so that the axial displacement of the rotating body can be prevented, and thus smooth rotation of the rotating body can be ensured. .

  FIG. 2A shows a front view of the housing portion 206 or 208 as viewed from the axial direction S, and FIG. 2B shows a perspective view of the pair of housing portions 206 and 208. As shown in FIGS. 2A and 2B, the flat section and the curved section form an annular groove 211, and the annular groove 211 extends over the entire circumference. In FIG. 2A, the curved portion 214 (218) is partially broken, and it can be seen that a plurality of balls 210 are arranged in the circumferential direction in the annular groove 211. As described above, since the balls are arranged over the entire circumference, the load resistance performance in the radial direction can be improved. Since these balls 210 slide freely in the circumferential direction in the annular groove 211, it is preferable that the balls 210 are arranged with a clearance between adjacent balls. In the present embodiment, the annular groove 211 is not formed with a seat for placing individual balls in a fixed position, and the balls 210 can move along the entire circumference. Smooth rotation is possible. Of course, a mode in which a seat for accommodating individual balls in a fixed position is formed in the annular groove 211 is also conceivable.

  The curved sections 214, 218 are formed such that the distance between the edge of the curved section and the flat sections 212, 216 is smaller than the diameter of the ball 210, and the ball 210 is press-fitted into the curved section. Is preferred. Thereby, the ball 210 can be reliably accommodated in the accommodating portion without fear of dropping off. In the illustrated example, the pair of accommodating portions 206 and 208 are formed and arranged in a mirror image symmetry, but can be formed and arranged asymmetrically in accordance with the application and use situation.

  FIG. 3 shows a bearing 250 according to the second embodiment of the present invention. In contrast to the bearing 200 shown in FIG. 1 in which the rotating body is disposed on the radially outer side of the annular support body, the bearing 250 is configured such that the rotating body 204a is disposed on the radially inner side of the annular support body 202a. 206a and 208a are arranged such that the contact portion between the ball 210 and the rotating body 204a is radially inward. That is, the support has a central hole 213, and the pair of storage portions 206a and 208a are configured such that the bottom of the curved section is radially outward from the stored ball 210. Therefore, the pair of accommodating portions 206a and 208a are fitted into the central hole 213 of the support body with the bottom of the curved section placed on the inner peripheral wall 215 of the central hole 213 of the support body. Other configurations will be apparent to those skilled in the art from the configurations shown in FIGS.

  Next, the operation of the first and second embodiments of the present invention will be described.

  When a radial force is applied to the rotating body 204 of the bearing 200 (250), the force is transmitted in the order of the peripheral end portion 209 of the rotating body 204, the ball 210, the pair of accommodating portions 206 and 208, and the support body 202. . Since this radial force can be finally received by the support 202, the bearing of this aspect can easily withstand the radial load. In addition, since the pair of curved portions 214 and 218 accommodating the ball 210 are arranged side by side in contact with each other, the rotating body can be stably supported.

  On the other hand, when a force is applied in the direction from the rotating body 204 to the side wall 207 along the axial direction S, the force is applied from the rotating body 204 to the flat section 216 of one accommodating portion arranged in the direction of the applied force. To the opposite side wall 207. Thus, axial forces can finally be received at the side wall 207. In this way, when a force acts on the rotating body in the axial direction toward the side wall 207 of the support body, the rotating body tends to move relative to the support body, so the side wall of the peripheral end 209 and the support body 202 One flat section 216 inserted between the side walls 207 is sandwiched between both side walls. For this reason, the accommodating portion is fixed and can support the rotating body 204 in a stable state via the ball 210. Therefore, the bearing of this aspect can be configured to easily withstand an axial load in at least one direction.

  Next, a procedure for assembling the bearing according to the first embodiment of the present invention will be described with reference to FIGS.

  First, one accommodating part 206 is fitted (press-fit) to the support body 202 (FIG. 4A). Next, the sprocket gear 204 (rotating body) is placed so as to be in contact with the ball 210 accommodated in the press-fit accommodating portion 206 (FIG. 4B). Next, the other accommodating portion 208 is fitted (press-fitted) into the support body 202 (FIG. 4C). Eventually, the curved sections come into contact with each other, and the sprocket gear 204 (rotating body) is arranged in contact with the ball between the flat sections of the pair of accommodating portions, and is completed (FIG. 4D). .

  As described above, the bearings 200 and 250 according to the embodiment of the present invention have a simple configuration in which the balls are accommodated in the accommodating portions 206 and 208 each having the flat section and the curved section, and are capable of handling axial and radial loads. Can withstand. In the configuration of the present invention, for example, the housing can be formed as shown in FIGS. 1 and 2 by processing only one metal (for example, iron) thin plate. Even if a rotating body having a large diameter is used, a significant reduction in weight can be achieved. Since it is possible to use a part of the rotating body and the support body where the bearing according to this embodiment is used as the rotating body and the support body, it is possible to further promote weight reduction. Furthermore, since the bearing of this embodiment also contributes to space saving, it can respond flexibly to the use which rotates the rotary body of various aspects on a support body.

  The bearings of FIGS. 1 to 3 are used for applications in which the rotating body rotates with respect to the annular support. However, if the rotating body 204 is fixed, the support 202 can be rotated with respect to this, Of course, it is needless to say that the application can be expanded to the usage form.

  Hereinafter, the Example which used the bearing and the bearing method which concern on embodiment of this invention for the electrically assisted bicycle is shown. A bearing according to an embodiment of the invention is indicated by reference numeral 70 in FIG.

  FIG. 5 shows an outline of the electrically assisted bicycle 1 to which the bearing according to the first embodiment of the present invention is applied. As shown in the figure, the main skeleton portion of the electrically assisted bicycle 1 is composed of a body frame 3 made of metal pipe, as in a normal bicycle. The body frame 3 includes a front wheel 20 and a rear wheel 22. , Handle 16 and saddle 18 are attached in a known manner.

  A drive shaft 4 is rotatably supported at the center lower portion of the vehicle body frame 3, and pedals 8L and 8R are attached to left and right ends thereof via crank rods 6L and 6R, respectively. A sprocket 2 is coaxially attached to the drive shaft 4 via a one-way clutch (99 in FIG. 7B described later) for transmitting only rotation in the R direction corresponding to the forward direction of the vehicle body. Yes. An endless rotating chain 12 is stretched between the sprocket 2 and a rear wheel power mechanism 10 provided at the center of the rear wheel 22.

  The electrically assisted bicycle 1 performs control to assist the pedaling force with an assist ratio (auxiliary power / stepping force) determined from at least the vehicle body traveling speed and the pedaling force. In this example, generation of assist power and assist control are executed by the assist power unit 11.

  An outline of the control system of the electrically assisted bicycle 1 is shown in FIG. The control system of the electric assist bicycle 1 is directly connected to one microcomputer 14 that collectively controls electronic processing of the entire bicycle, an electric motor 37 capable of PWM control, and the microcomputer 14, and its control signal And a battery 17 that is connected to the amplifier circuit 15 and supplies power to the electric motor 37.

  The microcomputer 14 receives at least a rotational speed signal for calculating a traveling speed and strain gauge signals 1 and 2 for calculating a pedaling force. Means for generating these input signals will be described later. The microcomputer 14 calculates the traveling speed and the pedaling force from these input signals, and performs electronic processing for determining the assist ratio based on a predetermined algorithm. Next, in order to instruct the electric motor 37 to generate auxiliary power corresponding to the determined assist ratio, the microcomputer 14 sequentially outputs PWM commands corresponding to the auxiliary power.

  Next, the auxiliary power unit 11 in the electric assist bicycle 1 will be described with reference to FIGS.

  The auxiliary power unit 11 shown in FIGS. 7A and 7B includes an assist gear 30 that is coaxially connected to the sprocket 2, an electric motor 37 that outputs electric power, and an assist gear from the output shaft 37a of the electric motor. And a gear mechanism 40 for transmitting electric force up to 30 through a gear. Therefore, when the electric motor 37 is rotated, the torque is provided to the assist gear 30 via the gear mechanism 40 and is immediately transmitted to the sprocket 2 fixed to the assist gear 30 and rotated by the pedaling force. Thus, the resultant force of auxiliary power and pedaling force is achieved.

  The gear mechanism 40 includes a first gear 38 interlocked with the output shaft 37 a of the electric motor 37, a second gear 42 for deceleration that meshes with the first gear 38, and the second gear 42 coaxially. And a third gear 45 that is connected and meshes with the assist gear 30.

  A so-called one-way clutch (not shown) that transmits power only in one direction is provided in the transmission path of auxiliary power from the electric motor 37 to the assist gear 30. The one-way clutch is configured and connected so as to transmit auxiliary power from the electric motor 37 to the assist gear 30 but not in the opposite direction, that is, from the assist gear 30 to the electric motor 37. When the electric motor 37 is not rotating, the rotational load of the motor is not transmitted to the assist gear 30 by the one-way clutch (not shown), and a light operation is possible.

  The sprocket 2, the assist gear 30, the electric motor 37, and the gear mechanism 40 are attached on the common base 50. The electric motor 37 and the entire gear mechanism 40 are fixed so as not to move with respect to the common base 50. Furthermore, the first gear 38 and the second gear 42 of the electric motor 37 and the gear mechanism 40 are covered with the drive housing 13. The drive housing 13 is connected to the common base 50 or formed integrally with the common base 50.

  The sprocket 2 is rotatably attached to the drive shaft 4 on the common base 50 via a one-way clutch 99. The one-way clutch 99 transmits only the forward rotation applied to the drive shaft 4 to the sprocket 2 as will be described later. The drive shaft 4 is rotatably supported in a shaft housing 52, and the shaft housing 52 is fixed to the vehicle body frame while being inserted into a shaft hole 80 formed in the vehicle body frame. The shaft housing 52 is connected to the common base 50 or is integrally formed.

  The sprocket 2 and the assist gear 30 are coaxially connected via pins 123 (in the example of FIG. 7A, three locations at intervals of 120 degrees). As a result, the electric power transmitted to the assist gear 30 is transmitted to the sprocket 2 via the pin 123. As shown in FIG. 7B, the pin 123 is attached through the assist gear 30 and the sprocket 2 in the thickness direction. In the example of FIG. 7B, the leg portion of the pin 123 is inserted and fixed in the hole portion of the assist gear 30, and the head portion of the pin 123 passes through the hole formed in the sprocket 2. The tip of the pin 123 has a diameter larger than the diameter of the hole to prevent the pin from coming off.

  Further, an elastic member 129 such as rubber is provided around the head portion and the shaft portion of the pin 123. That is, the elastic member is provided in the engagement region between the sprocket 2 and the pin 123. Thereby, the backlash etc. of the assist gear 30 and the sprocket 2 can be absorbed, and the power transmission between the assist gear 30 and the sprocket 2 can be made very smooth.

  The connecting means between the sprocket 2 and the assist gear 30 is not limited to the illustrated pins. For example, a bolt may be used, or the leg portion of the pin 123 may be integrally formed with the assist gear 30. The elastic member 129 may be provided on any power transmission path of the assist gear 30, the pin 123, and the sprocket 2. For example, it may be provided alone or additionally in the engagement region between the assist gear 30 and the pin 123.

  The assist gear 30 is rotatably attached to the common base 50 via the bearing 70 according to the embodiment of the present invention, independently of the sprocket 2. Thereby, more stable power transmission from the assist gear 30 to the sprocket 2 becomes possible.

  In the bearing 70, a pair of housing portions 71 and 72 that respectively accommodate the balls 73 and 74 are disposed on a bottom plate 77 that is a part of the common base 50, and the inner peripheral wall portion of the central bore of the assist gear 30 is disposed on the ball 73. , 74. Further, in the present bearing 70, the flat section of the housing portion 71 is disposed between the rear plate 75 that is a part of the common base 50 and the assist gear 30, and the flat section of the housing portion 72 is disposed with the assist gear 30. The cover plate 76 is connected to the assist gear 30.

  As described above, the sprocket 2, the assist gear 30, the electric motor 37, the gear mechanism 40, and the drive shaft 4 are mounted on the common base 50. Further, the control system circuit shown in FIG. By mounting the sensors inside the drive housing 13 and the one-way clutch 99, it is possible to configure one auxiliary power unit 11 that incorporates all the components necessary for electric assist. Thereby, simplification of the whole auxiliary power mechanism can be achieved, and attachment of the auxiliary power unit 11 to the vehicle body frame can be facilitated. It will be understood that the auxiliary power unit 11 can be attached to any type of body frame by appropriately processing the common base.

  The procedure for attaching the auxiliary power unit 11 to the bicycle frame will be described with reference to FIG. FIG. 8 (a) is a perspective view seen from the right side when the auxiliary power unit 11 is attached to the bicycle frame, FIG. 8 (b) is an enlarged view of the auxiliary power unit 11 shown in FIG. 8 (a), FIG. 8F shows a perspective view seen from the left side when the auxiliary power unit 11 is attached to the bicycle frame.

  First, as shown in FIG. 8C, the drive shaft 4 (covered by the shaft housing 52) of the auxiliary power unit 11 is inserted from one end of the shaft hole 80 along the direction of the arrow. Next, as shown in FIG. 8 (d), the auxiliary power unit 11 is inserted from the opposite end of the shaft hole 80 until the tips of the drive shaft 4 and the shaft housing 52 project, and attached to the projecting tip. The metal fitting 82 and the fastener 84 are attached. Further, a raised portion having bolt screw holes formed at both ends is provided in the auxiliary power unit 11, and a pair of tabs each having a bolt hole and extending in parallel are provided in the vehicle body frame. ), The raised portion may be arranged with the bolt holes aligned between the pair of tabs.

Finally, as shown in FIG. 8C, the fastening member 84 is fastened to the distal end portions of the drive shaft 4 and the shaft housing 52 to fix them, and the distal end portion of the attachment fitting 82 that is simultaneously fastened by the fastening member 84 is fixed. Bolts to the outside of the auxiliary power unit 11. Moreover, a bolt is fastened from both ends to the bolt screw hole of the raised part arrange | positioned in a pair of tab. As described above, the auxiliary power unit 11 can be securely and easily attached to the vehicle body frame.
(Treading force detection mechanism)
A pedal force detection mechanism for outputting strain gauge signals 1 and 2 input to the microcomputer 14 will be described with reference to FIGS. This pedaling force detection mechanism detects a distortion that changes due to the deformation of the one-way clutch 99 according to the pedaling force.

  As shown in FIG. 7B, the sprocket 2 is pivotally supported on the drive shaft 4 via a one-way clutch 99. The one-way clutch 99 includes a piece portion 100 and a tooth portion 112 as shown in FIG.

  In the piece part 100, three ratchet pieces 102 are arranged on the second engagement surface 110 at equal angles along the circumferential direction. The ratchet piece 102 is made of a rigid body, and is rotatable about an axis along the substantially radial direction of the second engagement surface 110. When the ratchet piece 102 is not acting on the ratchet piece 102, the piece rises so that the length direction forms a predetermined angle with respect to the second engagement surface 110 (equilibrium direction 160 in FIG. 10). The spring 104 is biased. As shown in FIG. 10, when the ratchet piece 102 is biased from the equilibrium direction 160 in the ascending direction a or the descending direction b, the piece raising spring 104 is slightly applied to the ratchet piece 102 so as to return the bias to the equilibrium direction 160. Exerts an elastic force.

  A piece bore 106 for receiving the drive shaft 4 is formed in the central portion of the piece portion 100, and the piece bore 106 also penetrates the cylindrical portion 103 protruding from the back surface 101 of the piece portion 100. . On the back surface 101, a circular groove 155 (FIG. 7B) is formed on the outer periphery of the cylindrical portion 103, and a large number of steel balls 152 are rotatably fitted in the circular groove 155. . As a result, a bearing for an axial load bearing and sliding bearing is formed on the back surface 101.

  The disc spring 124 is brought into contact with the back surface 101 of the piece portion 100 through the cylindrical portion 103 in the center hole 127. At this time, the disc spring 124 is slidably in contact with the back surface 101 via the steel ball 152, that is, the load receiving bearing, in a direction that opposes the pressure from the piece portion 100 with elasticity. On the surface of the disc spring 124, strain gauges 126 are installed at two locations facing each other with a positional relationship of 180 degrees. These strain gauges 126 are electrically connected to the microcomputer 14 via lead wires 128. More preferably, three or more strain gauges may be installed on the disc spring 124. At this time, it is preferable that the plurality of strain gauges are installed on the surface of the disc spring 124 so that each is in a rotationally symmetric position.

  The disc spring 124 is accommodated in the inner bottom portion 132 of the bowl-shaped supporter 130. The supporter 130 is formed with a support bore 133 for penetrating the drive shaft 4 and a support cylindrical part 134 protruding from the rear surface. A screw is cut on the outer peripheral surface of the support cylindrical portion 134, and the support 130 is fixed to the vehicle body by screwing the screw into the threaded inner wall of the vehicle body attachment portion 145. A bearing 138 corresponding to both axial and radial loads is engaged with the inner wall of the support cylindrical portion 134 (see FIG. 7B), and the bearing 138 is supported by a stopper inclined surface 144 formed on the drive shaft 4. Locked. Similarly, since a bearing (see FIG. 7B) is attached to the opposite side of the drive shaft 4, the drive shaft 4 is rotatable with respect to the vehicle body.

  Four first anti-rotation grooves 108 extending in the axial direction 5 are formed in the inner wall of the piece bore 106. Four second anti-rotation grooves 140 extending in the axial direction 5 so as to face the first anti-rotation groove 108 are also formed on the outer wall portion of the drive shaft 4 that is in sliding contact with the inner wall of the piece bore 106. ing. As shown in FIG. 11 (a), the first anti-rotation groove 108 and the second anti-rotation groove 140 facing the first anti-rotation groove form a cylindrical groove extending along the axial direction. Inside, a large number of steel balls 150 are accommodated so as to fill them. Thereby, the piece part 100 can move along the axial direction 5 with the minimum frictional resistance, and the relative rotation with respect to the drive shaft 4 is prevented. This is a kind of ball spline, but other types of ball splines, such as an endlessly rotating ball spline, can be applied as the slidable rotation preventing means.

  Further, as a method of attaching the piece portion 100 to the drive shaft 4, it is possible to use means other than the ball spline of FIG. For example, as shown in FIG. 11B, a projecting portion 140a extending in the axial direction is provided on the drive shaft 4, and a third anti-rotation groove 108a that accommodates the projecting portion 140a is formed in the piece portion 100. A key spline type is also applicable as a rotation prevention means. In FIG. 11B, the protrusion 140a may be provided on the piece 100 side and the third anti-rotation groove 108a may be provided on the drive shaft 4 side. Furthermore, as shown in FIG. 11 (c), a fourth anti-rotation groove 108b extending in the axial direction and a fifth anti-rotation groove 140b facing this are provided in the piece portion 100 and the drive shaft 4, respectively. A so-called key groove type in which the key plate is accommodated in a rectangular parallelepiped groove formed by the groove is also applicable as the rotation preventing means.

  A plurality of ratchet teeth 114 for engaging with the ratchet piece 102 are formed on the first engagement surface 121 of the tooth portion 112. The ratchet teeth 114 are configured by steep slopes 118 and gentler slopes 116 with respect to the first engagement surface 121, which are alternately and periodically formed along the circumferential direction of the tooth portion. .

  The tooth portion 112 is pivotally supported by the drive shaft 4 via the collar 111 so as to be slidable so that the first engagement surface 121 faces the second engagement surface 110 of the piece portion 100. At this time, the ratchet piece 102 and the ratchet teeth 112 are engaged (FIG. 10). That is, the drive shaft 4 is operatively connected to the tooth portion 112 only through the engagement portion between the ratchet piece 102 and the ratchet tooth 112. A washer 122 is fitted to the end 142 of the drive shaft 4 that has passed through the tooth bore 120 via the collar 111 so that the tooth 112 does not shift outward in the axial direction (FIG. 7B). The sprocket 2 is attached to the tooth portion 112 so as not to move via the pin 123 (FIG. 7B), and a pedal shaft 146 is attached to the tip of the drive shaft 4. Thus, the ratchet gear for connecting the drive shaft 4 and the sprocket 2 so as to transmit only the rotation by the pedal depression force in the vehicle body forward direction to the sprocket 2 is completed.

  Preferably, the offset spring 136 is interposed between the stopper inclined surface 144 of the drive shaft 4 and the back surface 101 of the piece portion 100. The offset spring 136 is configured to generate a clearance between the steel ball 152 accommodated on the back surface 101 and the disc spring 124 when the pedal depression force is equal to or less than a predetermined value (for example, substantially close to zero). 100 is biased axially.

  Next, the operation of this pedal effort detection mechanism will be described.

  When the rider applies a pedaling force to the pedals 8R and 8L (FIG. 5) and rotates the drive shaft 4 in the vehicle body forward direction, the rotational force is pivotally supported with respect to the drive shaft 4 so that it cannot rotate and can slide. Is transmitted to the frame unit 100. At this time, as shown in FIG. 10, the ratchet piece 102 is given a force Fd corresponding to the pedal depressing force from the piece portion 100, so that its tip portion comes into contact with the steep slope 118 of the ratchet teeth of the tooth portion 112. Try to transmit this force to the ratchet teeth. Since the ratchet teeth 112 are connected to the sprocket 2, the tip of the ratchet piece 102 receives a force Fp due to a load for driving from a steeper slope 118. The ratchet piece 102 to which opposite forces Fp and Fd are applied from both ends thereof rotates in the direction a and rises. At this time, the piece part 100 moves inward in the axial direction when the ratchet piece 102 rises, and pushes the disc spring 124 interposed between the piece part 100 and the supporter 130. The disc spring 124 opposes this and acts the elastic force Fr on the piece part 100. The force Fr and the force reflecting the pedal depression force that moves the piece portion 100 in the axial direction are balanced in a short time. Thus, the stress strain of the disc spring 124, the clearance between the piece portion 100 and the tooth portion 112, the angle of the ratchet piece 102 with respect to the second engagement surface 110, the position of the piece portion 100 with respect to the vehicle body frame, and the disc spring 124 are pushed in. The pressure applied is a physical quantity that reflects the pedal effort. Therefore, it is possible to estimate the pedal effort T by detecting at least one of these.

  In this example, the stress strain of the disc spring 124 is detected as an example. The microcomputer 14 adds at least the signals from the two strain gauges 126 provided on the disc spring 124 (including an average calculation). By averaging and measuring the amount of stress strain at multiple locations in this way, the output change can be increased and the noise component can be smoothed even with the same pedaling force, improving the SN ratio and further improving the pedaling force estimation accuracy. Can be made. This effect increases as the number of strain gauges increases.

  Further, when the pedal depression force is less than a predetermined value, the offset spring 136 creates a clearance between the back surface 101 of the piece 100 and the disc spring 124, so that the steel ball 152 is frequently applied to the disc spring 124. Less impact. Thereby, the noise component of the strain gauge signal can be reduced, and the stability of the pedaling force detection and the electric assist control can be improved.

  Next, the microcomputer 14 calculates an assisting auxiliary power Te to be applied based on at least the calculated pedaling force T, and calculates and outputs a control signal for instructing the electric motor 37 to be driven to rotate by the auxiliary power. To do. Preferably, the microcomputer 14 converts the rotational speed signal detected by the rotational speed sensor 220 into a vehicle speed, determines an appropriate auxiliary power Te based on both the pedaling force T and the vehicle speed, and generates the auxiliary power Te. The electric motor 37 is controlled.

The above pedal force detection mechanism has the following more excellent effects.
(1) Since the one-way clutch and the pedaling force detection mechanism are realized by one mechanism, the number of parts can be reduced, and a reduction in size, weight and cost can be achieved.
(2) The disc spring that integrates the load receiving unit and the load detection sensor is used for the part that detects the treading force, and the two functions are realized in one unit. Cost can be achieved.
(3) As shown in the above items (1) and (2), the pedal force detection mechanism has been made smaller, lighter, and simplified at a higher level. Sex has further expanded.
(4) For the reasons described in the above items (1) and (2), the load transmission loss is reduced as compared with the conventional mechanism, and an assist feeling with good control responsiveness can be realized.
(5) For the reasons shown in the above items (1) and (2), there is no unnecessary movement (until the sensor senses) the pedal compared to the conventional mechanism (using a coil spring), and the feeling when the pedal is depressed The conventional mechanism had a feeling of elasticity when depressed, whereas in the above example, it was the same as the feeling of a normal bicycle.

  It should be noted that whether one of the piece and the teeth of the one-way clutch 99 is attached to the sprocket and the other is attached to the drive shaft can be arbitrarily changed. For example, the piece portion 100 may be attached to the sprocket side, the tooth portion 112 may be slidably and non-rotatably attached to the drive shaft 4, and the disc spring 124 may be pushed by the tooth portion 112.

  Further, in the above example, the stress distortion of the disc spring is detected as a physical quantity related to the pedaling force. However, the present invention is not limited to this, and an arbitrary physical quantity that changes due to deformation according to the pedaling force of the one-way clutch 99 is detected. can do. For example, the inclination of the ratchet piece, the relative distance between the ratchet piece part and the ratchet tooth part, the position of the ratchet piece part and the ratchet tooth part with respect to the vehicle body, and the pressure for pressing the disc spring are selected as physical quantities reflecting the pedaling force. be able to.

  Furthermore, the type and shape of the elastic body arranged against the deformation of the one-way clutch 99 can be arbitrarily and suitably changed. For example, a rubber elastic body can be used in addition to the disc spring and the coil spring. Further, as a means for detecting stress strain, a strain gauge is taken as an example, but the present invention is not limited to this as long as a physical quantity related to stress strain can be detected.

  The above is the embodiment of the present invention, but the present invention is not limited to the above-described example, and can be arbitrarily modified within the scope of the gist of the present invention.

FIG. 1 is a side sectional view and a simplified front view of a bearing according to a first embodiment of the present invention. 2 is a front view of one housing portion for the bearing shown in FIG. 1 (FIG. 2A), and a perspective view in a state where a pair of housing portions for the bearing are in contact (FIG. b)). FIG. 3 is a side sectional view and a simplified front view of a bearing according to a second embodiment of the present invention. FIG. 4 is a diagram showing a procedure for assembling the bearing according to the first embodiment shown in FIGS. 1 and 2. FIG. 5 is a schematic view of an electrically assisted bicycle to which the bearing of FIG. 1 according to the first embodiment of the present invention is applied. FIG. 6 is a schematic diagram showing a control system of the electrically assisted bicycle shown in FIG. 7A and 7B are diagrams showing auxiliary power attached to the electrically assisted bicycle shown in FIG. 5, wherein FIG. 7A is a side view and FIG. 7B is a cross-sectional view. FIG. 8 is a schematic diagram for explaining a procedure for attaching the auxiliary power shown in FIG. 7 to the bicycle frame, and (a) is a perspective view seen from the right side when the auxiliary power is attached to the bicycle frame; 8B is an enlarged view of the auxiliary power shown in FIG. 8A, FIG. 8C is a perspective view before the auxiliary power is attached to the bicycle frame, and FIG. (E) is a perspective view when the auxiliary power is fixed to the bicycle frame, and (f) is a perspective view viewed from the left side when the auxiliary power is attached to the bicycle frame. FIG. FIG. 9 is an exploded perspective view of the one-way clutch shown in FIG. FIG. 10 is a diagram showing a fitting state of teeth and pieces of a one-way clutch (ratchet gear) for explaining the principle of pedaling force detection of the electrically assisted bicycle shown in FIG. FIG. 11 is a view showing an example of rotation preventing means for preventing relative rotation of the piece portion with respect to the drive shaft. FIG. FIG. It is a sectional side view of the radial ball bearing regarding a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric assist bicycle 2 Sprocket 4 Drive shaft 11 Auxiliary power 12 Chain 13 Drive housing 14 Microcomputer 15 Amplifier circuit 17 Battery 22 Drive wheel (rear wheel)
30 Assist gear 37 Electric motor 37a Output shaft of electric motor 38 First gear
40 gear mechanism 42 second gear 45 third gear 50 common base 52 shaft housing 70 bearing 80 shaft hole 99 one-way clutch 100 piece portion 102 ratchet piece 112 tooth portion 114 ratchet tooth 123 pin 124 plate disk spring 126 strain gauge 129 elasticity Member 200 Bearing (first embodiment)
202 Support body 203 Annular side part 204 Rotating body 206, 208 Housing part 207 Annular side wall 209 Circumferential end part 210 Ball 211 Annular groove 212, 216 Flat section 214, 218 Curved section 250 Bearing (second embodiment)
202a Support 206a, 208a Housing part

Claims (20)

A bearing comprising a pair of annular accommodating portions for accommodating a plurality of balls in order to rotatably support a rotating body with respect to a support,
Each of the pair of receiving portions includes an annular flat section and a curved section that extends in the axial direction from the flat section and is curved to receive the ball, the flat section and the curved section. Form an annular groove in which the plurality of balls are arranged side by side in the circumferential direction, the height of the edge of the flat section is higher than the height of the accommodated ball, and the height of the edge of the curved section is Less than the height of the contained ball,
The pair of housing portions are fitted to the support body in a state where the curved section of one housing portion faces the curved section of the other housing portion,
The rotating body is disposed in contact with the ball between a pair of flat sections, and the rotating body is rotatable with respect to the support body by sliding on the ball.   The bearing according to claim 1, wherein the annular groove extends over the entire circumference.   The bearing according to claim 2, wherein the plurality of balls are arranged with a clearance between adjacent balls so as to freely slide in the circumferential direction in the annular groove.   The bearing according to any one of claims 1 to 3, wherein the pair of housing portions are press-fitted into the support body.   The bearing according to any one of claims 1 to 4, wherein the pair of housing portions are formed and arranged so as to be mirror-image symmetrical with each other.   The bearing according to any one of claims 1 to 5, wherein the curved section of the one housing portion and the curved section of the other housing portion are in contact with each other.   The bearing according to any one of claims 1 to 6, wherein at least one of the pair of flat sections is disposed between the rotating body and a side wall extending from the support body.   The bearing according to claim 1, wherein the curved section is formed such that a distance between an edge of the curved section and the flat section is smaller than a diameter of the ball. The pair of storage portions is configured to be radially inward of the ball in which the bottom of the curved section is stored, and the rotating body has a central hole,
The pair of accommodating portions are fitted to the outer side in the radial direction of the support body with the bottom of the curved section placed on the outer peripheral wall of the support body, and the rotating body has an inner peripheral wall of the central hole. The bearing according to any one of claims 1 to 8, wherein the bearing is slidably disposed on the ball in contact with the ball. The support has a central hole, and the pair of storage portions are configured to be radially outward from the ball in which the bottom of the curved section is stored,
The pair of accommodating portions are fitted in the center hole of the support body in a state where the bottom of the curved section is placed on the inner peripheral wall of the center hole of the support body, and the rotating body is The bearing according to any one of claims 1 to 8, wherein an outer peripheral wall is slidably arranged on the ball in contact with the ball. A method of bearing a rotating body rotatably with respect to a support,
A pair of accommodating portions for accommodating a plurality of balls, each of the pair of accommodating portions, an annular flat section, and an annular shape that extends in an axial direction from the flat section and accommodates the balls The flat section and the curved section form an annular groove in which the plurality of balls are arranged side by side in a circumferential direction, and the height of the edge of the flat section is received Preparing the pair of accommodating portions higher than the height of the ball, wherein the height of the edge of the curved section is lower than the height of the accommodated ball;
One of the pair of accommodating portions is fitted to the support,
The rotating body is placed so as to come into contact with the ball accommodated in the accommodating portion fitted,
The other housing portion is fitted to the support body so that the curved section of the other housing portion of the pair of housing portions faces the curved section of the one housing portion. It is disposed in contact with the ball between the flat sections of the pair of receiving portions, and the rotating body is capable of rotating with respect to the support body by sliding on the ball. ,Method.   The method according to claim 11, wherein in the step of preparing the pair of accommodating portions, an accommodating portion in which the annular groove extends over the entire circumference is prepared.   13. The step of preparing the pair of accommodating portions, wherein the plurality of balls are arranged with a clearance between adjacent balls for sliding freely in the circumferential direction within the annular groove. the method of.   14. The step of fitting the one and the other accommodating portions to the support includes the step of press-fitting the one and the other accommodating portions into the support. 14. Method.   The pair of housing portions are formed so as to be mirror-image symmetric with each other, and the step of fitting the one and the other housing portions to the support body arranges the one and the other housing portions in a mirror image symmetry. 43. A method according to any one of claims 11 to 42, comprising a step.   The step of fitting the other housing portion to the support includes the step of bringing the curved section of the one housing portion into contact with the curved section of the other housing portion. The method according to item.   The step of fitting the one accommodating portion to the support includes a step of arranging a flat section of the one accommodating portion at a position adjacent to a side wall extending from the support, and mounting the rotating body. The placing step includes a step of arranging a flat section of the one accommodating portion between the rotating body and a side wall extending from the support body. the method of.   18. The method according to claim 11, wherein in the step of preparing the pair of accommodating portions, an accommodating portion in which an interval between an edge of the curved segment and the flat segment is smaller than a diameter of the ball is prepared. The method described. The pair of storage portions is configured to be radially inward of the ball in which the bottom of the curved section is stored, and the rotating body has a central hole,
The step of fitting the one accommodating portion into the support is performed by adjusting the diameter of the support so that the bottom of the curved section of the accommodating portion is placed on the outer peripheral wall of the support. A step of fitting outward in the direction,
The step of placing the rotating body includes the step of placing the rotating body such that an inner peripheral wall of a central hole of the rotating body is in contact with a ball housed in the one housing portion,
The step of fitting the other accommodating portion into the support is performed by adjusting the diameter of the support so that the bottom of the curved section of the accommodating portion is placed on the outer peripheral wall of the support. Fitting the outer side in the direction, and bringing the inner peripheral wall of the central hole of the rotating body into contact with the balls accommodated in the one and the other accommodating portions, thereby enabling the rotating body to slide on the balls The method according to any one of claims 11 to 18. The support has a central hole, and the pair of storage portions are configured to be radially outward from the ball in which the bottom of the curved section is stored,
The step of fitting the one accommodating portion into the support body includes supporting the one accommodating portion so that the bottom portion of the curved section of the accommodating portion is placed on the inner peripheral wall of the central hole of the supporting member. A process of fitting into the body,
The step of placing the rotating body includes a step of placing the rotating body such that an outer peripheral wall of the rotating body is in contact with a ball accommodated in the one accommodating portion,
The step of fitting the other housing portion to the support body includes supporting the other housing portion so that the bottom of the curved section of the housing portion is placed on the inner peripheral wall of the central hole of the support body. The method includes the steps of: fitting to a body; and contacting an outer peripheral wall of the rotating body with a ball accommodated in the one and the other accommodating portions, thereby enabling the rotating body to slide on the ball. The method of any one of thru | or 18.

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