Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1993-12-02
2000-05-23
Martin, David
Electricity: motive power systems
Induction motor systems
Primary circuit control
318812, H02P 138
Patent
active
060669357
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a fan installation having at least one pole-changing asynchronous motor for driving the fan.
To maintain the temperature of the cooling water of an internal combustion engine (for instance a diesel engine) within a narrow range (about 5.degree. C.), the amount of air through the radiator, and thus the speed of rotation of the cooling fan, must be adjustable. Three-phase asynchronous motors are used to drive the fan due to their robustness. The fans are powered either from an auxiliary operating power supply or from a three-phase generator which is driven by the internal combustion engine which is to be cooled.
Fan installations having at least one pole-changing asynchronous motor for driving the fan are known in diesel electric locomotives. In such fan installations, several pole-changing asynchronous motors may be provided. The amount of air can then be varied by the switching a different number of fans on and off and/or by switching the poles of the fan drive motor. With, for instance, three two-step asynchronous motors, a six-step regulation of the speed of rotation is thus obtained. Due to the characteristic of the diesel engine and the different environmental conditions, changes in speed of rotation and thus switch-overs are frequently necessary.
A fan unit in which stepwise regulation of the speed of rotation is effected by pole changing of a two-step fan drive motor is known from French Patent Application FR-A-2 607 187. Within one step, the speed of rotation of the fan is substantially proportional to the speed of rotation of the combustion engine and thus proportional to the frequency of the generator feeding the fan drive motor, the generator being driven by the combustion engine. Within one step, continuous regulation of the fan drive motor is not possible.
U.S. Pat. No. 3,584,728 describes a control device for cranes, the characteristic of which, however, is very different from that of a fan drive. Thus, for example, in the case of crane drives, the power is substantially proportional to the speed of rotation of the drive motor, which in the case of fan installations, the output is proportional to the third power of the speed of rotation of the drive motor.
Furthermore, fan installations in which the non-pole-changing asynchronous motor is fed via a converter are known. In this way, the speed of rotation can be continuously regulated and the temperature of the cooling water thus kept within narrow limits, and the frequent switchings-over or switchings-on avoided. Unfortunately, these fan installations are very expensive.
In view of the numerous drawbacks of the known fan installations, there is a need to provide a fan installation in which the speed of rotation of the fan, and thus the amount of air, can be matched in simple manner to the amount of heat to be dissipated, in particular with the fewest possible switchovers or switchings-on.
SUMMARY OF THE INVENTION
This need is achieved in accordance with the present invention by providing the fan installation with a regulating device by which the speed of rotation of the asynchronous motor can be continuously adjusted within a predeterminable speed range.
In the fan installation of the present invention, a pole-changing asynchronous motor is provided as drive motor for the fan. The speed of rotation of the drive motor is continuously adjustable within a predetermined range of speeds of rotation by controlling the voltage.
The ranges of speeds of rotation which can be freely selected within the overall range of speeds of rotation of the drive motor are preferably divided into an upper speed range, being step-wise adjustable, and a lower speed range, being continuously adjustable. The drive motor is then supplied with a voltage proportional to the frequency in the high-power stage (small number of poles), i.e., in the upper speed of rotation range. In the lower power stage (larger number of poles), the speed of rotation of the drive motor is continuously changed via the voltage. By r
REFERENCES:
patent: 3308363 (1967-03-01), Rawcliffe et al.
patent: 3584278 (1971-06-01), Krabbe
patent: 4489265 (1984-12-01), Kuznetsov
patent: 4644242 (1987-02-01), Takata et al.
patent: 4784580 (1988-11-01), Takata et al.
patent: 4928051 (1990-05-01), Demeter et al.
Martin David
Siemens Aktiengesellschaft
LandOfFree
Pole-changing asynchronous fan motor with continuously adjustabl does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pole-changing asynchronous fan motor with continuously adjustabl, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pole-changing asynchronous fan motor with continuously adjustabl will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1839276