Detachable Coils Air Core Movement Holder

A variety of analog meters are known, and widely used for measuring and recording the quantity or rate of flow of gas, electricity, or water passing through it, by means of the operation of a movement and a pointer. In recent years, analog meters have been gradually replaced by digital meters. However, a digital meter is relatively expensive, and may be interfered by outside noises or ambient conditions. Further, a digital indicator meter is not suitable for use in motor vehicles because it is difficult to realize the quantity or rate by a glance. When a figure, for example: 35 KM or 65 KM was read out, one must use brains to judge if such figure represents a low speed or high speed. The pointer of an analog meter directly indicates the amount of movement, and its movement can be easily seen even when the intensity of ambient light is low.

The movement of an analog meter may be made from moving coil, moving iron or air core, etc. according to its purpose. An air core movement, as shown in FIG. 1, is also known as "cross coils movement", which comprises a center shaft connected to a permanent magnet at the center mounted within two vertically connected bobbins, and two coils A and B wound round the bobbins. Coil A is equally wound round the bobbins at two opposite sides relative to the center shaft. Coil B is wound round the bobbins crossed over coil A and equally arranged at two opposite sides relative to the center shaft. During the winding of coils A and B, the bobbins may be caused to deform. If the coils A and B deform the bobbins, the center shaft may be stuck during the operation. Further, if the number of turns of either coil A or B is not equally distributed at two opposite sides relative to the center shaft and the tension of either coil A or B is not uniformly distributed, the total impedance of coils A and B will be different, thereby causing a indication error. This coil winding method can not get rid of the effect of outside temperature. Further, coil A produces a poor heat dissipating effect because it is covered within coil B, thereby resulting in an unbalanced impedance. When the impedance is unbalanced, the accuracy of the indication will be affected. Because the coil winding process is difficult to perform, the manufacturing speed is hindered. Because this conventional production method can not eliminate high defective rate, a lot of time will be spent on correction. Furthermore, the application of the bonding agent to fasten the ends of the wires greatly increases material and labor costs.

The present invention has been accomplished under the aforesaid circumstances. It is therefore the main object of the present invention to provide a detachable coils air core movement holder which is inexpensive to manufacture, and easy to assembly.

FIG. 1 is a perspective view of a prior art cross coils movement holder with the coil thereon;

FIG. 2 is an exploded view of a detachable coils air core movement holder according to the present invention; and

FIG. 3 is a perspective assembly view of the moving coil type movement holder of FIG. 2.

Referring to FIG. 2, a detachable coils air core movement holder in accordance with the present invention is generally comprised of an upper holder 1, a bottom holder 2, and a plurality of bobbins 3.

The upper holder 1 comprises a flat base plate 11 having a plurality of vertical bolt housings 12 and horizontal projections 16 alternatively disposed around the border at equal interval, and an upright hollow post 14 upstanding from the base plate 11 at the center, wherein each bolt housing 12 has a center through hole 13 through its length into which a respective copper bolt (as shown by imaginary line) inserts; the hollow post 14 has a center through hole 15 through its length.

The bottom holder 2 fits over the upper holder 1 at the bottom, comprising a plurality of vertical bolt housings 22 and horizontal projections 26 alternatively disposed around the border of a flat base plate 21 thereof at equal interval, and a recessed chamber 24 with a center blind hole 25 (not shown) on the top of the flat base plate 21 at the center, wherein each bolt housing 22 has a center through hole 23 through its length longitudinally aligned with the center through hole 13 on either bolt housing 12 of the upper holder 1. A magnet with a center shaft (as shown by imaginary line) is inserted in the recessed chamber 24 and retained between the top and bottom holders 1,2 with its center shaft extended out of the hollow post 14 and coupled to a pointer (this is similar to the prior art).

After the upper holder 1 and the bottom holder 2 connected in a stack, the horizontal projections 16 of the upper holder 1 are respectively connected to the horizontal projections 26 of the bottom holder 2 for mounting the bobbins 3.

Each bobbin 3 comprises a frame body 33 having two outward flanges 31,32 on two opposite ends thereof and a center through hole 34 through the frame body 33. Therefore, a coil can be wound round the frame body 33 and retained between the outward flanges 31,32.

Referring to FIG. 3, when assembled, the bobbins 3 are respectively mounted on the horizontal projections 16, 26 and protected between the vertical bolt housings 12, 22. Because the coils are respectively wound round the bobbins 3 before the assembly process of the movement holder, the assembly process is easy. Because there is a flat, broad space around the hollow post 14, a zero-reading calibrating device may be mounted on the upper holder 1 for easy calibration. In case the movement fails to work properly, the bobbins 3 can be conveniently removed from the upper and bottom holders 1,2 for repair. Further, a magnetizing element may be respectively inserted in the center through hole 34 of each bobbin 3 to make up the deficit, if the intensity of magnetic field is insufficient during the production.

While only one embodiment of the present invention has been shown and described, it will be understood that various changes and modifications could be made thereunto without departing from the spirit and scope of the invention.