JPH0240561Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a braking device that brakes the rotational movement of a shaft inserted into a cylinder. Regarding a braking device that applies braking to the rotation of a shaft by applying a coating, a stable braking force can be obtained by forming knurled grooves in a direction perpendicular to the rotational direction of the shaft on the outer periphery of the shaft. It is designed to reduce the machining accuracy required for the cylinder and shaft.

1 to 3 show a conventional braking device for raising and lowering a pickup arm of a record player. In Figures 1 to 3, 1 is a cylinder integrally formed on a resin substrate (not shown), 2 is a cylinder fixed to the inside of the cylinder 1 with screws 3, and 4 is a cylinder. 2 is a shaft rotatably inserted into the center hole; 5 is a retaining ring fitted to the tip of the shaft 4; 6 is a drive plate fastened to the rear end of the shaft 4 with a nut 7; 8 is a cylinder 2; and a drive plate 6, and an R washer 9 for positioning the shaft 4 in the direction of arrow A is suspended between the drive plate 6 and a pin 10 provided on the base plate,
A spring with a small biasing force that constantly biases the drive plate 6 to rotate in the direction of arrow C; 11 is a lever for lifting and lowering the pick-up arm swaged at the tip of the drive plate 6;
12 is an electromagnet attached to the substrate; 13 is its iron core; 14 is a coil spring that always urges the iron core 13 in the direction of arrow D; the coil spring has a larger urging force than the coil spring 9; 15 is between the cylinder 2 and the shaft 4; viscous fluid such as viscous oil applied to The pick-up arm is arranged so as to be rotatable in a direction perpendicular to the plane of the paper in FIG. 1, and its lower surface is placed on the lever 11.

In the above configuration, when not playing, the urging force of the coil spring 14 pushes out the iron core 13 in the direction of arrow D, and the lever 11 is rotated in the direction of arrow B at its tip, so that the pick-up arm above it is in the raised position. be.

During performance, current flows through the electromagnet 12, causing the iron core 13 to
resists the biasing force of the coil spring 14 and moves toward arrow E.
being sucked into the direction. Therefore, the lever 11 and the drive plate 6 are rotated in the direction of arrow C by the biasing force of the coil spring 9. At this time, the viscous fluid 15 applied between the cylinder 2 and the shaft 4 exerts a braking force on the rotation of the shaft 4, so that the lever 11 rotates slowly. Therefore, the pick-up arm placed on the lever 11 is also gently lowered onto the record disc.

However, when the cylindrical shaft 4 is inserted into the cylindrical cylinder 2 and the viscous fluid 15 is applied between them, the viscous fluid 15 is controlled by the size of the gap between the cylinder 2 and the shaft 4. There is a problem that the power varies greatly. According to experiments,
It has been confirmed that the control force changes greatly between the first rotation after applying the viscous fluid 15 to the entire outer circumference of the shaft 4 and the second and subsequent rotations. In other words, from the second time onwards, it will rotate with less than half the force of the first time. Similarly, when the brake is rotated again after being left for a while, the braking force changes greatly between the first and second and subsequent rotations. This is because the viscous fluid 15 adheres almost uniformly to the entire outer circumference of the shaft the first time, so the initial friction is very large, and from the second time onwards, the viscous fluid 15 is unevenly distributed to some extent on the outer circumference of the shaft 4, causing friction. This is thought to be because the force becomes smaller.

To solve this problem, the inner diameter of the cylinder 2 and the outer diameter of the shaft 4 must be finished with high precision, and the gap between them must be made extremely small. However, in this case, it becomes difficult to manufacture the cylinder 2 and the shaft 4, leading to an increase in costs. Further, there is a problem in that it is susceptible to variations in viscosity, and when the viscosity of the viscous fluid 15 changes due to changes in temperature, etc., the braking force also changes significantly.

The present invention provides a braking device that solves these conventional problems with a simple configuration.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5.

In FIGS. 4 and 5, parts having the same functions as those in FIGS. 1 to 3 are denoted by the same reference numerals, and explanations thereof will be omitted. A knurled groove 16a is formed on the outer periphery of the cylinder 16 in a direction perpendicular to the direction of rotation.
is formed.

In this way, the viscous fluid 15 enters each of the knurled grooves 16a, and the viscous fluid 15 adheres to substantially the entire outer circumference of the shaft 16. Moreover, since the amount of the viscous fluid 15 that has entered each groove 16a flowing into the adjacent grooves 16a is extremely small, no matter how many times the shaft 16 is rotated, the viscous fluid 15 is hardly unevenly distributed. Therefore, a constant frictional force is always obtained, and uniform braking force can be applied. Further, even if the finishing accuracy of the shaft 2 and cylinder 3 is not made too high, a more stable rotational speed can be obtained than in the conventional system. Therefore, the cost required for manufacturing the cylinder 2 and shaft 4 is also low. Furthermore, since the amount of viscous fluid applied between the cylinder 2 and the shaft 4 increases, it is less susceptible to variations in the viscosity of the viscous fluid, and in this respect as well, stable braking force can be obtained.

Incidentally, in the above embodiment, the explanation has been given of the application to raising and lowering the pick-up arm, but it goes without saying that the invention can also be applied to other things. Further, the knurled groove 16a does not necessarily correspond to the shaft 16.
It is not necessary to provide the entire length in the axial direction, but it may be provided in a part of the axial direction.

As described above, the present invention forms a knurled groove in a direction perpendicular to the rotational direction of the shaft on the outer periphery of a shaft that is rotatably inserted into the center hole of a cylinder, and allows viscous fluid to flow between the cylinder and the shaft. Since it is designed to be applied, uneven distribution of the viscous fluid can be prevented by allowing the viscous fluid to enter each knurled groove one by one, and a uniform braking force can always be applied. Also, there is no need to finish the cylinder or shaft with particularly high precision.
There is no increase in cost either. Furthermore, since a large amount of viscous fluid can be applied between the cylinder and the shaft, an excellent effect can be obtained in that the braking force is not affected much even if the viscosity of the viscous fluid itself varies.

[Brief explanation of the drawing]

Figures 1 and 2 are a sectional view and a side view of a conventional braking device, Figure 3 is a sectional view of its main parts, and Figures 4 and 5 are a sectional view and its essential parts of an embodiment of the present invention. FIG. 1... Cylindrical body, 2... Cylinder, 6... Drive plate, 7... Nut, 9, 14... Coil spring, 11... Lever, 12... Electromagnet, 13...
Iron core, 15... Viscous fluid, 16... Shaft, 1
6a...Knurled groove.

Claims (1)

[Scope of utility model registration request] A shaft is rotatably inserted into the center hole of the cylinder, and a viscous fluid is applied between the cylinder and the shaft to brake the rotation of the shaft. A braking device characterized in that a knurled groove is formed in a direction perpendicular to the direction of the braking device.