受験番号：22IPM022

問１[0002]
The most required property of a golf club (herein after referred to as “club”) is that apath of the ball hit by the club does not curve (or hardly curves). Although it isimportant to pursue such property of the club, a golfer also has great interest in finding
a club that matches to him or her. Conventionally, the club is produced by taking static
characteristics such as the length of the club shaft (herein after referred to as “shaft”),
balance, the weight of the club and hardness of the shaft, into account, and the golfer
has to select the club by judging or guessing these characteristic values based on his or
her past experience, or completely based on his or her intuition.
[0003]On the other hand, golf swing is dynamic behavior, so that attention has been drawn toselection of the club taking a dynamic characteristic, i.e. the natural frequency (whichmeans the primary natural frequency of bending vibration) of the club into account.
The natural frequency is a value controlled by the bending rigidity of the shaft, theweight of the shaft, the length of the shaft, and the weight of the club head (herein afterreferred to as “head”), as outlined below. Namely, during a down swing, the shaft isbent and restores its shape. It is considered that the head speed reaches the maximal
speed when the shaft restores its shape and becomes straight. Accordingly, by hitting
the ball at this moment, the maximum flying distance by the swing can be obtained(provided that the face of the head is directed toward a proper direction). It is said thatthe natural frequency of the golf club has relation to such swing behavior. If thenatural frequency of the club is smaller than the most preferable frequency, the clubreaches the hitting point before the maximal head speed is obtained. On the otherhand, if the natural frequency of the club is larger than the most preferable frequency,
the ball will be hit after the head speed reached the maximal speed, resulting in
reduction of the flying distance and deterioration of controllability of the flying
direction.
問2[0025]As shown in Fig. 3, when the flange 10 of the holder 7 is held in pressing contact withthe side face of the outer ring 2, a friction force acting on the contact surface becomes arotational resistance of the holder 7. When the friction force exceeds an elastic force of

the elastic body 11, the inner ring 1 and the holder 7 are relatively rotated, and theroller 6 engages the cylindrical surface 3 and the cam surface 5, whereby the rotation of
the inner ring 1 is transmitted to the outer ring 2 via the roller 6. Also, the elastic body
11 is elastically deformed by the relative rotation of the inner ring 1 and the holder 7.
[0026]In the state where a rotary torque is transmitted between the inner ring 1 and the outerring 2, when a load of an axial force with respect to the flange 10 is released, the holder
7 is rotated toward a neutral position by elastic restoration of the elastic body 11. By
this rotation of the holder 7, the engagement of the roller 6 with the cylindrical surface
3 and the cam surface 5 is released, and the inner ring 1 is idly rotated. Further, since
the elastic body 11 is provided between the inner ring 1 and the holder 7, the roller 6
revolves together with the holder 7.
[0027]At this time, the roller 6 is biased toward the inner circumference of the outer ring 2 by
the elastic piece 9, and prevented from moving in a radially inner direction of the holder
7. Therefore, behavior of the roller 6 during a low-speed rotation of the inner ring 1 isstabilized, and a dragging torque applied to the holder 7 is small. Also, the roller 6 isprevented from being mistakenly engaged with the cylindrical surface 3 and the camsurface 5.
[0028]
Further, the roller 6 is prevented by the elastic piece 9 from moving in the radial
direction of the holder 7, so that the roller 6 does not repeatedly collide with thecylindrical surface 3 and the cam surface 5, and vibration due to the collision of theroller 6 is hardly generated. Thus, a two-way roller clutch having excellent vibration
properties can be obtained.
問3
An electromagnetic bearing (10) for an axial force member (11) comprising a rotation
axis (12) and a distal region outwardly extending from the rotation axis (12), theelectromagnetic bearing (10) comprising:an annular magnetic iron member (14) comprising a single coil (15) and a pair ofextrusions (20, 21), the magnetic iron member (14) striding the distal region of the axialforce member (11), the pair of extrusions (20, 21) having opposite surfaces facing theaxial force member (11), the opposite surfaces defining a magnetic flux control gap on
the respective opposite sides in the axial direction of the axial force member (11), andthe coil (15) generating an electromagnetic control magnetic flux route (22) through themagnetic flux control gap, whereby the axial force member (11) is positioned withrespect to the magnetic iron member (14) in the axial direction; anda pair of annular permanent magnets (16, 17) attached to the magnetic iron member(14) and having opposite surfaces facing the axial force member (11), the pair ofpermanent magnets (16, 17) defining a pair of magnetic gaps at a position radiallyspaced from the magnetic flux control gap, and the pair of permanent magnets (16, 17)
generating bias flux routes (18, 19) through the pair of magnetic gaps, each of the bias
flux routes (18, 19) being parallel to the electromagnetic control magnetic flux route (22),and more than a half of the length of each bias flux route differs from theelectromagnetic control magnetic flux route (22).