JPH0217923B2 - - Google Patents

Abstract

PURPOSE:To freely adjust the load of rotary torque by utilizing a friction force generated electromagnetically between a permanent magnet and solenoid. CONSTITUTION:An iron core 5 is attracted by a permanent magnet 2 and is moved toward the surface of a bearing 3 under the condition that the power is not applied to a coil 7. Therefore, it is necessary for rotating a load shaft 1 to supply a larger rotating force to dominate a friction force due to a contact pressure generated between the end surface of iron core 5 and the end surface of bearing 3. A friction force increases by exciting the solenoid coil so that the magnetic flux in the same direction as that generated by the magnet 2 is generated and a larger rotating force is required for dominating such friction force. On the contrary, a friction force is reduced by exciting the solenoid coil so that the magnetic flux which cancels that generated by the magnet 2 is generated and finally the condition where friction is zero can be formed.

Description

Detailed Description of the Invention (Technical Field) The present invention utilizes a rotary load variable solenoid that can variably adjust the rotary load, more specifically, a permanent magnet and a solenoid coil, and uses a rotary load variable solenoid that can variably adjust the rotary load. The present invention relates to a variable rotational load solenoid that can freely adjust rotational load torque using applied frictional force or the like.

(Background of the Invention) Appropriate loads and brakes are often required in rotating mechanisms such as precision machines, office machines, and consumer appliances.

For example, the tape can be fed more smoothly by applying an appropriate brake or load to the reel on the supply side using a magnetic tape feeding mechanism or the like.

In addition, this load is not uniform, and if it is possible to reduce the load at the beginning of the supply and increase it as it approaches the end of the supply, it is possible to always feed under the optimum condition and to minimize the power of the motor that supplies the power. can do. The same can be said about automatic film advance and automatic rewind in cameras, which have recently become commonplace.

However, in reality, there is no simple device that can perform such an operation, so a load is created using a friction force generated using a spring. Such a load is constant and cannot be changed from moment to moment. Another problem is that over a long period of time, the state of friction changes and the load changes.

In large tape recorders and the like, a configuration is used in which motors are arranged on the supply side and the take-up side, each motor is alternately loaded, and the degree of the load is controlled. However, such a configuration is large-scale and either increases the size of the entire device or can only be used for devices that are inherently large.

(Object of the Invention) An object of the present invention is to provide a small-sized variable rotational load solenoid that can arbitrarily adjust the rotational load.

(Structure of the Invention) To achieve the above object, a variable rotational load solenoid according to the present invention includes first and second magnetic bearings, and a cylinder magnetized in the axial direction and provided on the outer periphery of the first bearing. a permanent magnet, a non-magnetic load shaft rotatably supported by the first and second bearings, and a magnetic material integrally provided with the load shaft and rotatable between the bearings. a solenoid coil consisting of a bobbin and a coil wound around the bobbin provided on the outer periphery of the iron core, the first bearing, the permanent magnet and the second bearing; the first bearing; permanent magnet,
It consists of a second bearing and a yoke that covers the outer periphery of the solenoid coil, and the torque required to rotate the load shaft can be adjusted by adjusting the contact pressure between the iron core and the bearing using the current flowing through the coil. It is configured.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings and the like.

FIG. 1 is a diagram showing an embodiment of a variable rotational load solenoid according to the present invention, and is partially cut away along a plane including the central axis.

FIG. 2 is a partially cutaway view of the embodiment taken along a plane perpendicular to the axis.

This embodiment is designed with the idea of automating the assembly in mind, and allows assembly based on the inner diameter of the bobbin 8 of the solenoid coil. A cylindrical permanent magnet 2 is fitted and integrated into the first bearing 3 made of a magnetic material. This cylindrical permanent magnet 2 is magnetized in the axial direction.

This assembly of the bearing 3 and the permanent magnet is fitted into the inner diameter of the bobbin 8 and supported.

The coil wound on bobbin 8 is connected to bobbin terminal 8.
a and other terminals (not shown), and an operating current is supplied from the outside.

A deep counterbore hole is provided on the right side in the figure of the second bearing 4 made of a magnetic material, and a disk-shaped spacer 6 made of a non-magnetic material and having a through hole in the center is fitted into this hole. This assembly of the second bearing 4 and the spacer 6 is fitted into the inner diameter of the bobbin 8 from the other side of the bobbin. Note that the spacer 6 is used for adjusting the magnetic circuit resistance, etc.

A cylindrical magnetic core 5 is integrally provided on the non-magnetic load shaft 1 . The outer diameter of this iron core 5 is smaller than the deep counterbore of the second bearing 4 and smaller than the minimum inner diameter of the bobbin 8 (see FIG. 2). The load shaft 1 is connected to the first and second bearings 3,
When supported within the bobbin 4, the iron core 5 is rotatable in the space within the bobbin 8 together with the shaft.

The axial movement of the iron core 5 is caused by the spacer 6 and the first
It is limited by the surface of the bearing 3, which only ensures the clearance necessary for rotation.

The yoke body 9 is a cylindrical container made of magnetic material,
The inner diameter of the yoke main body 9 is adapted to the flange of the bobbin 8 and is fitted from the first bearing side, and a yoke lid 10 is fitted from the second bearing 4 side to form a yoke.

This yoke covers the outer circumferences of the first bearing 3, the permanent magnet 2, the second bearing 4, and the solenoid coil, forming a part of a magnetic circuit.

Note that if the gear 11 is fixed to the load shaft 1, the force for rotating the load shaft 1 can be transmitted via the gear 11.

In the device having the above configuration, even when the coil 7 is not energized, the iron core 5 is attracted by the permanent magnet 2 and the first
is attracted to the surface of the bearing 3. Therefore, in order to rotate the load shaft 1, it is necessary to supply a rotational force that overcomes the frictional force caused by the contact pressure between the end face of the iron core 5 and the end face of the first bearing 3.

If the solenoid coil is excited to generate a magnetic flux in the same direction as the magnetic flux generated by the permanent magnet 2,
The frictional force will increase and a greater rotational force will be required to overcome the friction.

Contrary to the above, if the solenoid coil is excited to generate magnetic flux in a direction that cancels out the magnetic flux generated by the permanent magnet 2, the frictional force will gradually decrease, and eventually a state of zero friction can be achieved.

FIG. 3 is a graph for explaining the operating characteristics of the variable load solenoid.

The vertical axis shows the torque (gram force/cm) required to rotate the load shaft on a logarithmic scale, and the horizontal axis shows the voltage supplied to the solenoid coil. The curve shows the operating characteristics of the example.

Approximately 11 g/cm of torque is required to rotate the load shaft without energizing the solenoid coil, which generates a voltage in the forward direction (direction that generates magnetic flux in the same direction as the permanent magnet), and When the torque is increased, 14 g/cm at 1V, 10V
It weighs approximately 60 grams/cm.

When a reverse voltage is applied, the torque is 1 gram force/cm at 4.5V, and the applied voltage is approximately
When the voltage is set to around 8V (not shown), the torque becomes 0.
state can be formed.

(Modifications) Various modifications can be made to the embodiments described in detail above within the scope of the present invention.

By inserting thin materials with different coefficients of friction between the first bearing 3 and the iron core 5, the load range can be changed.

The curve in Figure 3 shows the characteristics when a synthetic resin disc with a low coefficient of friction is inserted.

It can be seen that the torque has decreased significantly. When 0.5V is applied in the opposite direction, the torque is 1g/cm
When the applied voltage is further increased to approximately 3V, the torque can be reduced to zero.

The coil 7 is divided into left and right halves in FIG. 1 and wound to form a three-terminal structure, and by excitation by various left and right combinations, more diverse operations can be performed.

(Effects of the Invention) As described above in detail, the rotary load variable solenoid according to the present invention can freely adjust the load torque using the solenoid current.

Therefore, it is also possible to automatically control the load torque by configuring a control circuit loop including this rotary load variable solenoid.

Further, since no movement mechanism other than rotation is required and the structure is simple, the entire device can be made compact.

The length of the yoke of the device of the above embodiment is 18 mm, and the diameter of the yoke is 12 mm, making it very compact. Therefore, it can be widely applied to optical machines, office machines, audio equipment, video equipment, etc.

Furthermore, since the solenoid coil is shielded by the yoke, generation of leakage magnetic flux is prevented.

[Brief explanation of drawings]

FIG. 1 is a view showing an embodiment of a variable rotational load solenoid according to the present invention, and is a partially cutaway view taken along a plane including a central axis. FIG. 2 is a partially cutaway view of the embodiment taken along a plane perpendicular to the axis. FIG. 3 is a graph for explaining the operation of the variable load solenoid. DESCRIPTION OF SYMBOLS 1... Load shaft, 2... Permanent magnet, 3... First bearing, 4... Second bearing, 5... Iron core, 6... Spacer, 7... Coil, 8... Bobbin, 9... ...Yoke, 10...Yoke lid, 11...Gear.

Claims (1)

[Scope of Claims] 1. First and second magnetic bearings, a cylindrical permanent magnet magnetized in the axial direction and provided on the outer periphery of the first bearing, and the first and second bearings. a non-magnetic load shaft that is rotatably supported by a non-magnetic load shaft; a magnetic iron core that is integrally provided with the load shaft and is rotatable between the bearings; the iron core and the first bearing; A solenoid coil consisting of a bobbin and a coil wound around the bobbin provided around the outer periphery of the permanent magnet and the second bearing, and the outer periphery of the first bearing, the permanent magnet, the second bearing and the solenoid coil. A rotary load variable solenoid comprising a covering yoke and configured to be able to adjust the torque necessary to rotate the load shaft by adjusting the contact pressure between the iron core and the bearing using a current flowing through the coil. 2. The variable rotational load solenoid according to claim 1, wherein the pair of magnetic bearings are fitted into the inner periphery of the bobbin. 3. The rotary load variable solenoid according to claim 2, wherein the yoke is cylindrical and forms a magnetic circuit between one pole of the permanent magnet and the second bearing.