Fan cooler

[0002] 1. Field of the Invention

[0003] This invention relates to a fan cooling device for electrical or electronic components, having a control circuit with a control stage and is designed to control a number of revolutions of a fan motor connected to the control stage as a function of preset values.

[0004] 2. Description of Prior Art

[0005] A fan cooling device of this type is known from German Patent Reference DE 40 24 046 A1. This known fan cooling device has a collectorless d.c. motor as the fan motor, which is driven in a manner wherein the number of revolutions is controlled as a function of an air temperature, wherein a minimum number of revolutions is associated with a lower fixed threshold temperature, and a maximum number of revolutions is associated with an upper fixed threshold temperature. The control circuit here is relatively elaborate.

[0006] One object of this invention is to provide a fan cooling device of the type mentioned at the outset, which permits manifold control options along with a simple design.

[0007] This object is attained by means of the characteristics described in this specification and set forth in the claims. A fan motor is an asynchronous motor, which is controlled by phase control. The control circuit includes a microcontroller connected upstream of a control stage. An optocoupler is switched between the control stage and the microcontroller and the microcontroller determines a phase control angle for control of the fan motor as a function of the detection of the crossover of the cullent of a control signal and of the preset values.

[0008] A simple control is possible using the asynchronous motor as the fan motor, wherein the provided power can be simply varied with a phase control which is known per se. It is easy to preset a desired control and to match the control to different conditions simply by connecting a microcontroller upstream of an actual control stage of the fan motor. In this case the microcontroller is only under a minimal load, since an optocoupler is arranged between the microcontroller and the control stage, which in addition results in a galvanic separation. The control data can be made available by the microcontroller without elaborate switching measures.

[0009] A simple change in the control can be achieved with preset values that include a minimum setting of the number of revolutions, a command value and an actual value. A minimum setting of the number of revolutions can be regulated by a unit for setting the minimum number of revolutions and the command value can be regulated by a command value presetting unit.

[0010] Furthermore, for connecting the microcontroller and for signal transmission, a further optocoupler is arranged between a crossover detection circuit and the microcontroller.

[0011] A further advantageous aspect of this invention is that the optocoupler is embodied as an opto-triac. As a result, the optocoupler can assume different switching functions.

[0012] If the fan is arranged in a switchgear cabinet, the microcontroller is connected to a higher-order switchgear cabinet control and a selection can be made by the switchgear cabinet control or manually. Thus, the microcontroller controls the fan motor either alone on the basis of preset values entered directly into the microcontroller, or on the basis of preset values supplied through the switchgear cabinet control. The fan cooling device for controlling the fan motor can be operated either autonomously or as a function from a higher-order control unit. In this case the fan cooling device can be a part of a total cooling arrangement, which comprises a combination of several control circuits with associated fans, or a combination of at least one control circuit with an associated fan and other cooling apparatus. The cooling devices can be controlled in accordance with a preset program by the switchgear cabinet control. For example, if a fan cooling device breaks down, its break-down can be compensated by other components of the total cooling arrangement. Also, a fan cooling device can be turned off, for example, if it operates incorrectly or if reduced noise generation is desired. These modes of operation can be selected by means of simple programming of the switchgear cabinet control.

[0013] This invention will be explained in greater detail in what follows, making reference to the drawing FIGURE which schematically represents a circuit diagram of a fan cooling device.

[0014] A fan cooling device arranged in a switchgear cabinet 12 has a control circuit 1 for a fan motor 11. The control circuit 1 is connected by means of an I²C-bus to a higher-order switchgear cabinet control 2. The control circuit 1 contains a microcontroller 4 as the central control component, which on the basis of preset values controls a control stage, not shown in detail in the drawing, via an optocoupler 10 in the form of an opto-triac which controls the fan motor 11. The microcontroller 4 receives signals regarding a crossover detection of the control signals for the fan motor with a further optocoupler 8. A minimum number of revolutions, as well as a command value for the temperature, can be set by means of a minimum number of revolutions setting unit 5 and a command value preset unit 7. An actual value detection unit 6 for determining an existing temperature is provided for control of the number of revolutions.

[0015] The control stage of the fan motor operates in accordance with the phase control method, wherein the microcontroller 4 issues a signal for the phase control angle depending on the required output of the fan motor 11. The microcontroller 4 is protected against the appearance of excess voltages by means of the optocoupler 10 and the optocoupler 8, and is also only put under a low load. In case of the appearance of an error, such as a sensor monitoring, a fan monitoring or an excess temperature monitoring, the microcontroller 4 can issue an interference report signal, which controls an interference report relay 9 for signaling the interference state.

[0016] The microcontroller 4 can either perform control of the fan motor 11 alone with preset values, which include the minimum number of revolutions, the actual value of the temperature and its command value, or it can be reversed by means of the switchgear cabinet control 2, so that the microcontroller 4 performs the control on the basis of data supplied by the switchgear cabinet control 2. Thus the fan cooling device can be operated as a part of a total control, for example in combination with other fan cooling devices or in combination with other cooling devices. In case of the appearance of an error, the fan cooling device can be switched off and its function can be taken over by another cooling device or the cooperation of other cooling devices. Multitudinous modes of operation can be realized by this linkage with the switchgear cabinet control by means of simple programming, which can also be fixed as a function of the time of day or as a function of the conditions of the surroundings.