Patent Application
20120007534
This application claims priority of Taiwanese Application No. 099122502, filed on Jul. 8, 2010.
1. Field of the Invention
The invention relates to a rotation speed control device, more particularly to a rotation speed control device for a heat-dissipating fan.
2. Description of the Related Art
A conventional heat-dissipating fan for a personal computer or a server is designed for operation at different rotation speeds to meet different requirements. In order to make the speed of the heat-dissipating fan comply with customer specifications, a voltage-controlled integrated circuit is used in combination with a control circuit having a custom set of resistance values so that suitable magnitudes of current may be generated. However, since there are many points of solder connection between the voltage controlled integrated circuit and the aforesaid control circuit, faulty connections are commonly found between the integrated circuit and the control circuit.
Another solution for making the speed of the heat-dissipating fan comply with customer specifications is to generate suitable magnitudes of current by using coils having different coil diameters or different numbers of turns instead of by changing resistance values. However, because different coil materials are required, inventory problems and higher manufacturing costs are incurred.
The object of the present invention is to provide a rotation speed control device capable of alleviating the aforesaid drawbacks of the prior art.
Accordingly, there is provided a rotation speed control device for a heat-dissipating fan including an impedance unit, a regulating unit, and a driving circuit. The impedance unit includes a first resistor having a first end connected to a first node, and a second end connected to a second node, and a second resistor having a third end connected to the second node, and a fourth end. The regulating unit is connected to the impedance unit and is configurable for varying an effective impedance of the impedance unit to adjust magnitude of current flowing through the impedance unit. The driving circuit is connected to the impedance unit and is adapted to control rotation speed of the heat-dissipating fan according to the magnitude of the current flowing through the impedance unit.
By virtue of the regulating unit of the rotation speed control device of the present invention, a variable impedance effect may be achieved without incurring higher manufacturing costs and inventory problems.
Other features and advantages of the present invention will become apparent in the fol lowing detailed description of the preferred embodiments with reference to the accompanying drawings, of which:
Before the present invention is described in greater detail with reference to the accompanying preferred embodiments, it should be noted herein that like elements are denoted by the same reference numerals throughout the disclosure.
Referring to
The impedance unit 21 includes a first resistor R1 having a first end connected to a first node 211, and a second end connected to a second node 212, and a second resistor R2 having a third end connected to the second node 212, and a fourth end. In this embodiment, the fourth end of the second resistor R2 is connected to a third node 213.
The regulating unit 22 is connected to the impedance unit 21 and is configurable for varying an effective impedance of the impedance unit 21 to adjust magnitude of current flowing through the impedance unit 21. The driving circuit 3 is connected to the impedance unit 21 and is adapted to control rotation speed of the heat-dissipating fan according to the magnitude of the current flowing through the impedance unit 21.
In this embodiment, the regulating unit 22 includes a first flow control contact unit 221 connected to the first node 211 and the second node 212 and configurable for selectively bypassing the first resistor R1.
When the first flow control contact unit 221 is opened, current is able to flow through the first resistor R1 and the second resistor R2. When the first flow control contact unit 221 is closed, the current is able to flow through the first flow control contact unit 221 and the second resistor R2. Closing of the first flow control contact unit 221 may be conducted by, for example, soldering.
Described below is an example of an embodiment of the rotation speed control device 2. In the example, the first resistor R1 has a resistance of 5 ohms, and the second resistor R2 has a resistance of 10 ohms. When an effective resistance of 15 ohms is required, the first flow control contact unit 221 is opened, so that current is able to flow through the first resistor R1 and the second resistor R2 so as to meet the requirement of an effective resistance of 15 ohms. On the other hand, when an effective resistance of 10 ohms is required, the first flow control contact unit 221 is closed, so that current is able to flow through the first flow control contact unit 221 and the second resistor R2 and does not flow through the first resistor R1 so as to meet the requirement of an effective resistance of 10 ohms.
In this embodiment, the driving circuit 3 is connected to the second node 212, and is further connected to a stator coil 4 of the heat-dissipating fan. Since the feature of the invention does not reside in the specific configuration of the driving circuit 3 and how it drives rotation of the heat-dissipating fan, further details of the same are omitted herein for the sake of brevity.
It is noted that the first flow control contact unit 221 may be connected electrically to the second node 212 and the third node 213 for selectively bypassing the second resistor R2 in other embodiments of the invention.
Referring to
In this embodiment, the regulating unit 22 includes a first flow control contact unit 221 connected to the first node 211 and the second node 212 and configurable for selectively bypassing the first resistor R1, and a second flow control contact unit 222 connected to the second node 212 and the third node 213 and configurable for selectively bypassing the second resistor R2.
When the first flow control contact unit 221 and the second flow control contact unit 222 are both opened, current is able to flow through the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4. When the first flow control contact unit 221 is closed and the second flow control contact unit 222 is opened, current is able to flow through the first flow control contact unit 221, the second resistor R2, the third resistor R3 and the fourth resistor R4. When the first flow control contact unit 221 is opened and the second flow control contact unit 222 is closed, current is able to flow through the first resistor R1, the second flow control contact unit 222, the third resistor R3 and the fourth resistor R4. When the first flow control contact unit 221 and the second flow control contact unit 222 are both closed, current is able to flow through the first flow control contact unit 221, the second flow control contact unit 222, the third resistor R3 and the fourth resistor R4. While the driving circuit 3 is connected to the fourth node 214 in this embodiment, the connection between the driving circuit 3 and the impedance unit 21 should not be limited to what is disclosed herein.
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In the following Table 1, the electrical potentials and rotation speeds for various possible connections in the second to eleventh embodiments are shown. It should be noted herein that
In the second to eleventh embodiments, apart from achieving the same effect as the first preferred embodiment, variations of the effective resistances of the rotation speed control device 2 are increased in number to expand flexibility of the same.
In summary, by virtue of the regulating unit 22 of the rotation speed control device 2 of the present invention, a variable impedance effect may be achieved without incurring higher manufacturing costs and inventory problems.
While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 099122502 | Jul 2010 | TW | national |
