GB2317277A

GB2317277A - Motor for heat dissipation fans

Info

Publication number: GB2317277A
Application number: GB9618466A
Authority: GB
Inventors: Alex Horng
Original assignee: Sunonwealth Electric Machine Industry Co Ltd
Current assignee: Sunonwealth Electric Machine Industry Co Ltd
Priority date: 1996-09-04
Filing date: 1996-09-04
Publication date: 1998-03-18
Also published as: DE29615898U1; GB9618466D0; FR2753585B3; FR2753585A3

Abstract

A motor for miniature heat dissipation fans includes a rotor, a stator, and a control circuit 2 electrically connected between the rotor and the stator. The stator includes a coil 1 having two connection points 11, 12 which are electrically connected to the control circuit 2 such that polarities of the two connection points are alternately changed to drive the rotor of the motor to rotate. The alternate switching of the coil is provided by transistors 22,23,26,27 controlled by a Hall element 3. The control circuit 2 can be an integrated circuit.

Description

Motor for Miniature Heat Dissipation Fans The present invention relates to a motor for miniature heat dissipation fans.

Fan motors are required to be minimized in volume in some cases for heat dissipation, e.g., fans for dissipating heat generated by integrated circuits. Fig. 5 of the drawings illustrates a circuit for a conventional motor for heat dissipation fans, Fig. 6 illustrates a conventional stator of a motor, and Fig. 7 illustrates a circuit of the conventional stator. Basically, a stator of a motor consists of two coils al and a2 which respectively activate two transistors cl and c2 to conduct by means of outputs of a Hall element b. This causes the two coils al and a2 to conduct alternately, thereby generating alternate magnetic fields to drive a rotor of the motor to rotate. The biggest problem in making miniature fan motors is the stator as it consists of two coils. The present invention is intended to provide a motor of a miniature heat dissipating fan having an improved stator which mitigates and/or obviates the above problems.

A motor for miniature heat dissipation fans in accordance with the present invention includes a rotor, a stator, and a control circuit electrically connected between the rotor and the stator. The stator includes a coil having two connection points which are electrically connected to the control circuit such that polarities of the two connection points are alternately changed to drive the rotor of the motor to rotate.

The control circuit, preferably an integrated circuit, includes a first group of transistors and a second group of transistors, the coil of the stator is electrically connected between two said transistors which are simultaneously conducted, thereby causing alternate currents in the coil.

Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

In the drawings: Fig. 1 is a control circuit of a motor for heat dissipation fans of the present invention; Fig. 2 is a perspective view of a stator of the present invention; Fig. 3 is a schematic illustration of a stator coil circuit of the present invention; Fig. 4 is a schematic view of an integrated circuit made from the control circuit of the present invention; Fig. 5 is a control circuit of a conventional motor for heat dissipation fans; Fig. 6 is a perspective view of a stator of the conventional motor; and Fig. 7 is a schematic illustration of a stator coil circuit according to prior art.

Referring to the Figs. 1 to 4 of the drawings and initially to Figs. 1 to 3, a motor for heat dissipation fans in accordance with the present invention includes a stator 1 which consists of a single coil 1 with two conduction connection points 11 and 12. The connection points 11 and 12 are controlled by a control circuit (alternate circuit) 2 to cause alternate conduction between positive pole and negative pole. The single coil 1 can generate the required alternate magnetic fields to drive a rotor of the motor to rotate.

The control circuit 2 illustrated in Fig. 1 includes a Hall element 3 which senses polarities (N or S) of magnetic poles and thus outputs pulse signals. When an output voltage of the Hall element is "High", three transistors 21, 22, and 23 are activated to conduct. Meanwhile, another transistor 24 is also "ON", and transistors 25, 26, and 27 are "OFF".

Accordingly, the connection point 11 forms a positive electric potential, the other connection point 12 forms a negative electric potential, and the current in the coil 1 flows from the connect ion point 11 to the connection point 12.

When an output voltage of the Hall element is "Low", four transistors 21, 22, 23, and 24 are "OFF1,. Yet, transistors 25, 26, and 27 are "ON". Accordingly, the connection point 11 forms a negative electric potential, the other connection point 12 forms a positive electric potential, and the current in the coil 1 flows from the connection point 12 to the connection point 11. Repetitiously alternate motions generate alternate currents in the coil 1.

Thus, the coil 1 generates alternate magnetic fields to drive the rotor of the motor to rotate.

Referring to Fig. 4, as described hereinbefore, the stator of the motor of the present invention includes only one coil 1. The transistors and resistances of the alternate circuit 2 may be made as a miniature integrated circuit under current semi-conductor technique, i.e., the alternate circuit 2 can be manufactured as a miniature chip 2', thereby providing a miniature heat dissipation fan motor.

When compared to a conventional stator for heat dissipation fans shown in Fig. 6, the coil 1 occupies a relatively small space as the height "hl" and outer diameter "dl" (see Fig. 2) thereof are only approximately a half of the height "h2" and outer diameter "d2" of the conventional one.

The single coil 1 of the present invention has further advantages. For example, the conventional stator includes two coils wherein the current of a reverse voltage tends to residue and flow in the coils, which causes an increase in temperature inside the coils, thereby shortening the life periods of the electric elements. Yet the stator of the present invention includes only one coil such that the increase of temperature inside the coil happens with a much smaller possibility. In addition, alternate conduction of the single coil of the present invention may eliminate the reverse voltage in the coil to lower the operative current of the motor, thereby improving the performance and efficiency of the motor. Furthermore, winding procedure required for one coil can be completed easily and quickly, which also guarantees quality of the coil in mass production.

Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the invention as hereinafter claimed.

Claims

Claims:

1. A motor for miniature heat dissipation fans, comprising: a rotor, a stator, and a control circuit electrically connected between the rotor and the stator, the stator comprising a coil having two connection points which are electrically connected to the control circuit such that polarities of the two connection points are alternately changed to drive the rotor of the motor to rotate.

2. The motor according to claim 1, wherein the control circuit includes a first group of transistors and a second group of transistors, the coil of the stator is electrically connected between two said transistors which are simultaneously conducted, thereby causing alternate currents in the coil.

3. The motor according to claim 1, wherein the control circuit is an integrated circuit.

4. The motor according to claim 2, wherein the control circuit is an integrated circuit.