受験番号：22IPM013

問１[0002]

Golf clubs (hereinafter, abbreviated as "clubs") have been most required to fly aball without curving (suppress curving).

Golfers not only put emphasis on suchcharacteristics of the clubs, but also have much interest in finding suited golf clubs fortheir own.

Hitherto, the clubs have been manufactured in consideration of static

characteristics such as a length of a club shaft (hereinafter, abbreviated as "shaft"),balance, weight of the club, and hardness of the shaft. Thus, golfers have no otherchoice than to select the clubs by estimating and judging values of those characteristics
based on their own past experiences or only with their filling.
[0003]
Meanwhile, the golf swing is a dynamic motion. Thus, attention has beendrawn to selection of the club in consideration of dynamic characteristics of the club,
specifically, natural frequency (more specifically, primary flexural natural frequency).
The natural frequency is influenced by flexural rigidity of the shaft, weight of the shaft,length of the shaft, weight of a club head (hereinafter, abbreviated as "head"). Outlineof the natural frequency is as follows. The shaft deflects and then reverts during adownswing. A head speed is maximum probably at a time when the shaft reverts to bestraight. Thus, by hitting the ball at this timing, a maximum flying distance by theswing is obtained (note that, a face of the head needs to be properly directed). The
natural frequency of the golf club is said to be relevant to such swings. When a naturalfrequency of a club used is relatively lower than an optimum natural frequency, the ballis hit before reaching the maximum head speed. When the natural frequency of theclub used is relatively higher, the ball is high after reaching the maximum head speed.
As a result, a flying distance is reduced, and directionality is deteriorated.

問２[0025]
As illustrated in FIG. 3, when the flange 10 of the cage 7 is held in press
contact with the side surface of the outer ring 2, frictional force to be applied to thecontact surface is generated as rotational resistance of the cage 7. When the frictional
force exceeds an elastic force of the elastic member 11, the inner ring 1 and the cage 7
are rotated relative to each other.

With this, the rollers 6 are engaged with thecylindrical surface 3 and the cam surfaces 5, and the rotation of the inner ring 1 istransmitted to the outer ring 2 through intermediation of the rollers 6. Further, when
the inner ring 1 and the cage 7 are rotated relative to each other, the elastic member 11
is elastically deformed.
[0026]
Under a state in which rotational torque is transmitted between the inner ring
1 and the outer ring 2, when the axial load to the flange 10 is removed, by elastic
restoration of the elastic member 11, the cage 7 is rotated toward the neutral position.
As a result of the rotation, the rollers 6 are disengaged from the cylindrical surface 3
and the cam surfaces 5, and the inner ring 1 is idled. Further, the elastic member 11 isinterposed between the inner ring 1 and the cage 7.

With this, the rollers 6 arerevolved together with the cage 7.
[0027]At this time, the rollers 6 are biased by the elastic pieces 9 toward the innerperiphery of the outer ring 2, and hence are prevented from moving toward the radiallyinner side of the cage 7. Thus, behavior of the rollers 6 during low speed rotation of theinner ring 1 is stabilized. With this, drag torque to be applied to the cage 7 is reduced,
and undesired engagement of the rollers 6 with the cylindrical surface 3 and the cam
surfaces 5 is prevented.
[0028]
Further, the elastic pieces 9 prevent the rollers 6 from moving in the radial
direction of the cage 7, and hence the rollers 6 do not repeatedly collide against thecylindrical surface 3 or the cam surfaces 5. As a result, vibration is scarcely generated
by the collision of the rollers 6. With this, a bi-directional roller clutch having excellent
vibration characteristics can be provided.

問３
1. An electromagnetic bearing (10), comprising:an axial member (11) having a rotary shaft (12) and a distal region expanding
outward from the rotary shaft (12);an annular magnetic iron-based member (14) including
a single coil 15, anda pair of projection portions (20 and 21),the pair of projection portions (20 and 21) having opposedsurfaces to be opposed to the axial member (11) across the distal region of the axial
member (11),theopposed

surfaces

defining

magnetic-flux

control

clearances on both end sides in an axial direction of the rotary shaft (12) of the axial
member (11),the coil (15) generating a magnetic flux path (22) across themagnetic-flux control clearances, to thereby position the axial member (11) in the axial
direction with respect to the magnetic iron-based member (14);a pair of annular permanent magnet (16 and 17)
mounted to the magnetic iron-based member (14),having opposed surfaces to be opposed to the axial member (11),defining a pair of magnetic clearances at a position radially away fromthe magnetic-flux control clearances, andgenerating bias magnetic flux paths (18 and 19) other than themagnetic flux path (22) across the pair of magnetic clearances, the magnetic flux paths(18 and 19) each being generated parallel to the magnetic flux path (22) in a region
having a length at least half of a height of each of the pair of annular permanent
magnet (16 and 17).