DEVICE FOR DRIVING ASSEMBLIES WHICH CAN BE ACTIVATED TEMPORALLY SUCCESSIVELY

DESCRIPTION

The invention relates to a device for driving assemblies which can be activated temporally successively, as per the preamble of claim 1.

The design and mode of operation of previously known devices of said type is complex since a high level of control or regulating expenditure is required, with corresponding control and regulating components, for activating the assembly which is to be activated temporally later.

It is therefore an object of the present invention to create a device for driving assemblies which can be activated temporally successively, as per the preamble of claim 1, which permits a reduction in the control or regulating expenditure for the activation of the assembly or assemblies which are to be activated after a time delay.

Said object is achieved by means of the features of claim 1.

The invention firstly utilizes the principle of a liquid friction clutch, as explained for example in DE 197 49 342 Al, the entire content of which document is hereby incorporated by reference in the content of disclosure of the present application.

Accordingly, the liquid friction clutch or viscous clutch has a reservoir for a shear fluid, a working chamber with at least one shear gap, and a stationary dynamic pressure element, by means of which the shear fluid can be transferred from the reservoir into the working chamber.

According to the invention, however, in contrast to the prior art, the liquid friction clutch has a first clutch section and a second clutch section. Here, the first assembly is assigned to the first clutch section and the second clutch section, which is assigned to the second assembly, is connected downstream of and is fluidically connected to the first clutch section. It is therefore possible to firstly actuate the first assembly by supplying shear fluid into the first clutch section, after which the second assembly can be connected to the drive device of the device according to the invention in a positively controlled fashion and temporally after the coupling- in of the first assembly.

In principle, therefore, control is possible by means of the finidically connected clutch sections merely by transferring the shear fluid from the first clutch section to the second clutch section, without further device-related regulating expenditure being required in addition to control or regulating components, such as a switching valve and an actuator, which are provided in any case.

The subclaims contain advantageous refinements of the invention. It is thus possible according to the invention to provide the first and second clutch sections with in each case only one shear gap. It is however also possible to provide both clutch sections with a plurality of such shear gaps by providing corresponding working chambers, such that, per clutch section, it is possible to increase the torque to be transmitted to the respective assembly.

In one particularly preferred embodiment of the invention, the first assembly is designed as a coolant pump, and the second assembly is designed as a fan wheel, of a motor vehicle cooling device. In said embodiment, it is possible with the principle according to the invention to firstly drive the pump wheel with the full drive power, and to subsequently activate the fan wheel after a time delay, in order to be able to correspondingly increase the cooling power if the operation of the pump wheel alone were no longer sufficient to provide the required cooling power.

Further details, features and advantages of the invention can be gathered from the following description of exemplary embodiments on the basis of the drawing, in which: Figure 1 shows a schematically highly simplified illustration of a first possible embodiment of the device according to the invention, and

Figure 2 shows an illustration, corresponding to figure 1, of a second embodiment.

In the illustrated example, the device 1 according to the invention is a part of a cooling device for internal combustion engines. The principles of the present invention are explained below on the basis of said example, wherein it is self- evident that the principles according to the invention may be applied to all devices for driving assemblies which can be activated temporally successively.

Furthermore, below, reference will be made to tw ^r o assemblies which can be activated temporally successively, wherein it should be highlighted that this is also merely an example, since it is also possible for more than two assemblies to be driven by means of the mode of operation according to the invention. The device or cooling device 1 accordingly has a first assembly in the form of a coolant pump 2 and a second assembly in the form of a fan wheel 3.

Furthermore, the device 1 is provided with a drive device 4 which, in the example, is symbolized by a belt pulley 20. The drive device 4 or the belt pulley 20 thereof is driven by a motor (not illustrated in figure 1), with the drive connection betw ^r een the motor and the belt pulley 20 taking place by means of a belt drive (likewise not illustrated). Alternative designs for the drive device 4 are of course likewise conceivable.

Furthermore, the device 1 has a liquid friction clutch 5 which has a housing 14 with a radially outer reservoir 15 and a first clutch section 6 and also a second clutch section 7. A stationary dynamic pressure tube 8 is also provided which, in interaction with a switching valve 12 which can be actuated by means of an actuator 13, can conduct shear liquid from the reservoir 15 into working chambers of the first clutch section 6 and of the second clutch section 7. Said working chambers are symbolized by shear gaps 11 and 16, with the respective shear liquid return line being symbolized by the dashed lines 9 and 10, which lead back into the reservoir 15.

The device 1 according to the invention accordingly has a liquid friction clutch or viscous clutch 5 which functions according to known operating principles. Here, the first assembly or the coolant pump 2 can be coupled by means of a shaft 17 to the first clutch section 6, while the second assembly or the fan wheel 3 can be coupled by means of a shaft 18 to the second guide section 7.

Since the two clutch sections 6 and 7 are flow-connected, in the event of an actuation of the switching valve 12, the first clutch section 6 is supplied with shear liquid first, such that torque is transmitted via the shaft 17 and the coolant pump 2 is rotated. Once the coolant pump 2 has reached its maximum power, an activation of the fan wheel 3 takes place without further regulating intervention by means of a transfer of the shear liquid from the first clutch section 6 into the second clutch

section 7, since, as a result of the activation of the second clutch section 7, a torque is transmitted via the shaft 18 to the fan wheel 3, which is thereby set in rotation.

In principle, the embodiment according to figure 2 is of the same design and has the same mode of operation, such that with regard to all the corresponding features and functions, reference can be made to the description of figure 1.

As shown by the diagrammatic illustration of figure 2, said embodiment differs from the embodiment according to figure 1 , which has only one shear gap, by a multiplicity of working chambers or shear gaps 11 and 16 of the first clutch section 6 and second clutch section 7 respectively. The resulting sequence of working chambers which are arranged in series makes it possible for torque to be transmitted according to how many working chambers or shear gaps are supplied with shear liquid, so as to permit a successive increase in the transmitted torque to the first assembly 2 or the second assembly 3.

In addition to the written disclosure above, reference is hereby explicitly made, for further explanation of the disclosure, to the diagrammatic illustration in figures 1 and 2.

List of reference symbols

Device for driving assemblies which can be activated temporally successively First assembly (coolant pump) Second assembly (fan wheel) Drive device Liquid friction clutch First clutch section Second clutch section Dynamic pressure tube (stationary) , 10 Return line for shear liquid 1, 16 Shear gap 2 Switching valve 3 Actuator of the switching valve 4 Housing 5 Reservoir 7, 18 Shafts 9 Overflow from the first clutch section 6 into the second clutch section 7 0 Belt pulley