JPS628423Y2 - - Google Patents

Description

[Detailed description of the invention] As a device for facilitating movement while receiving force, a device as shown in the example in Fig. 1 that holds a rolling ball freely in rotation is generally used. The force p ₁ given and received by the object 3 is transmitted to the object 3. In this case, each of the small balls 2 transmits force at three points: one point a on the surface of the rolling ball 1, and the side b and bottom c of the small ball receiver 7. The total force exerted on the ball 2 due to the three-point contact is therefore more than twice the force received from the rolling ball 1, and the resistance of the ball 2 to rotation or sliding increases accordingly. In addition, in order to ensure smooth rotation of the rolling ball 1, it is appropriate to set a gap of 3 μm or more to about 1/1000 of the diameter at each contact point, but in three-point contact, the ball contacts the rolling ball. The directional gap will be larger than in the case of two-point contact, and the position of the rolling ball will be correspondingly inaccurate.

The object of the present invention is to provide a device for holding a rolling ball that can freely rotate when subjected to an improved force such that the three-point contact of the small ball is changed to a two-point contact.

The details of this invention will be explained below with reference to the drawings showing one embodiment.

As shown in FIG. 2, in order to transmit the force p ₁ received by the rolling ball 1 to the object 3 with little loss, to ensure the accurate position of the rolling ball, and to not increase the size of the device more than necessary, The radius of the rolling ball r ₁
Rolling three or more n small balls 2 with a radius r ₂ that is less than 1/2 of the radius, the position of the force p ₁ received by the balls and the approximate ball 1
They are arranged in an annular shape at centrally symmetrical positions and held in a small ball receiver 4 having an annular concave surface fixed to the object 3 or fixed in position so as to freely rotate in a circle. The direction of the force _p1 that the rolling ball 1 receives is within the solid angle formed by the n small balls 2 with the center of the rolling ball, and the concave surface of the small ball receiver 4 is centered in the direction of the center of the rolling ball 1. It has an arc-shaped cross section with a radius r ₃ larger than r ₂ and smaller than r ₁ +2r ₂ , and is configured in an annular shape, and has n small spheres 2.
Roll and sandwich it between ball 1. Each small ball 2 rolls between a point d on the surface of the ball 1 and a point d on the concave surface of the ball receiver 4.
They make contact at point e and transfer force, but since the radius r ₃ of the cross-sectional arc of the concave surface is smaller than r ₁ + 2r ₂ , movement is limited to the circle, and regardless of the increase or decrease of force, the rolling ball will not move in the circle. The change in position relative to the ring will be extremely small. Separators 5 are provided to arrange the small spheres at substantially equal positions within the ring. Further, even when the rolling ball is not subjected to any force, a retainer 6 is provided to maintain the arrangement of each part of the device to prevent large changes in the position of the rolling ball.

According to the device for holding a rolling ball that is free to rotate according to the present invention, when the rolling ball 1 receives a force from a direction within a certain solid angle and attempts to rotate the rolling ball in a free direction at a specified position. When the small balls 2 interposed between themselves and the object 3 transfer force, the sliding and rolling resistance can be made extremely small by making two-point contact with each small ball, and the gap can also be made small, so that the rolling ball 1 with respect to the object 3 can be made extremely small. It is possible to precisely define the position of the rolling ball, and smooth movement and efficient force transmission by the rolling ball can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a conventionally used holding device for rolling balls that is free to rotate, and FIG. 2 is a cross-sectional view of the holding device for holding rolling balls that is free to rotate when subjected to a force according to the present invention. 1...Rolling ball, 2...Small balls (n pieces), 3...
Object, 4...Small ball receiver, 5...Separator, 6...
...Retainer, 7...Small ball receiver.

Claims (1)

[Scope of utility model registration request] In a device that applies force to a freely rotating rolling ball with radius r ₁ and transmits the force to an object that restricts only the position of the rolling ball, three small balls with radius r ₂ less than (1/2) r ₁ are used. In order to hold the small ball by arranging the above n pieces in a circular ring at the position where the rolling ball receives force and the center of the ball, a circle with radius r ₃ larger than r ₂ and smaller than r ₁ +2r ₂ is created. A circular concave surface with an arcuate cross section is provided, and each of the n small balls always rolls on one side of the surface of the ball.
It is configured so that contact is made for force transmission at only two points, a point and one point on the concave surface of the ring, ensuring free rotation of the rolling ball regardless of the increase or decrease in the force transmitted and received by the rolling ball. A holding device that allows a rolling ball to rotate freely and receives a force that allows it to be held in an accurate position.