Pumps – Condition responsive control of drive transmission or pump... – Disconnectable drive element
Reexamination Certificate
1997-12-30
2001-03-13
Thorpe, Timothy S. (Department: 3746)
Pumps
Condition responsive control of drive transmission or pump...
Disconnectable drive element
C417S364000, C417S214000, C123S041120
Reexamination Certificate
active
06200106
ABSTRACT:
The benefit is hereby claimed of the right to an earlier effective filing date based on PCT/EP97/01950 as provided for in 35 USC §120 and claims priority under 35 U.S.C. §119(e) based on U.S. Provisional Application Serial No. 60/025,865, filed Sep. 10, 1996.
TECHNICAL FIELD OF THE INVENTION
The invention relates to a fan for an internal combustion engine, with a fluid friction clutch inserted between a drive shaft and a fan wheel and with a locking device intended for the fan wheel and cooperating positively with the housing of the fluid friction clutch, said housing being equipped with the fan blades.
BACKGROUND OF THE INVENTION
A fan arrangement of this type is known from DE 34 20 277 C3. There, the housing of the fluid friction clutch, said housing being equipped with the fan blades, was assigned either a mechanically actuated brake or a mechanically actuated retaining rod, in order to stop the fan wheel completely, for example during a cold start, and thereby prevent the cooling air generated by the co-rotating fan from delaying the heating of the cooling fluid of the internal combustion engine. Both the brake provided there and the positively acting retaining device are actuated via a memory element which changes its shape abruptly at a specific coolant temperature and, since the memory element provided there is a coil, frees the fan wheel to rotate from a specific coolant temperature, while below this coolant temperature, that is to say, for example, during a cold start, it retains the fan wheel. In devices of this type, the drive arrangement, in particular the fluid friction clutch, must be provided correspondingly with a brake or, as proposed there, with a hollow drive shaft, through which an axially displaceable retaining rod is guided. This is complicated and also does not permit subsequent refitting. The changeover operation can also be triggered solely by the coolant temperature, specifically irrespective of the air temperature which controls the supply or discharge of oil to or from the clutch and which is recorded via a bimetal.
OBJECTS OF THE INVENTION
The object on which the present invention is based is to design in a simple way a retaining device of the type mentioned in the introduction, such that a retrofitting of existing fan drives and a control of the retaining device via other parameters of the engine control are possible.
SUMMARY OF THE INVENTION
To achieve this object, in a fan of the type mentioned in the introduction, there is provision for the locking device to be a detent element which engages directly on the outside of the housing of the fluid friction clutch and which can be actuated via an actuating member located in the circuit of the ignition lock and/or triggered by other parameters of the engine control.
By virtue of this design, when the detent element is actuated from the ignition circuit it is then guaranteed, during any starting operation, and, in particular, also during a cold start, that the fan wheel is stationary, so that, on the one hand, if the clutch is still full, the pumping-off operation can proceed as a function of the cooling air temperature, but, on the other hand, a co-rotation of the fan wheel itself when the clutch is empty is also reliably prevented. This design also leaves open the possibility of actuating or releasing the detent element as a function of other signals and, for example, of preceding the detent element with a delay element which, after the ignition has been switched off, in the event that the temperature of the coolant has not yet reached the predetermined value or has fallen short of it again, allows a renewed activation of the retaining device only some time after the fan wheel has come to a stop. Damage to the fan wheel as a result of mechanical interaction with the detent element is ruled out in this way.
In a development of the invention, the actuating member for actuating the detent element can be arranged in an electric circuit, together with the ignition lock and an additional switch which can be triggered by a thermal element for recording the coolant temperature. By virtue of this design, in normal operation the detent element is released when the coolant temperature is sufficiently high.
In a development of the invention, in this design an electromagnet can be provided as an actuating member, the function of said electromagnet being merely to bring the detent element into engagement with the housing of the fluid clutch. The power of such an electromagnet can be very low. There is therefore also the possibility of constructing the electromagnet from two windings which are located in separate circuits and, only when current is applied to them jointly, are capable of actuating the catch hook provided as a detent element. This embodiment affords the possibility of a simple safeguard which rules out an actuation of the retaining device under specific preconditions.
In a development of the invention, there can be provided as a detent element a bolt which engages into the interspace between cooling ribs of the housing of the fluid friction clutch. In a development, this bolt can be designed in a simple way as a catch hook which is pivotable at a fixed location and which is mounted on a holding device which, in particular, is arranged fixedly relative to the engine. This design makes it possible in a simple way for existing fan drives having a fluid friction clutch, the housing of which is usually provided with approximately radially projecting cooling ribs, also to be provided with a detent device while the holding device for the catch hook serving as a detent bolt can be mounted essentially at any desired points wherever room is available in the engine space. The actuation of a catch hook also requires very little electrical energy.
In a particularly advantageous development of the invention, the catch hook can be provided in a hook-like manner with a projecting wing composed of magnetically active material, this wing cooperating with the electromagnet. This design allows very simple actuation, in which the energy consumption for the electromagnet is very low. Finally, the catch hook thus designed can be provided in a simple way with a return spring, and, in order to save as much construction space as possible, the latter can be designed as a leaf spring which is seated firmly on the holding device and runs approximately parallel to the articulated part of the catch hook.
REFERENCES:
patent: 4004198 (1977-01-01), Cairo et al.
patent: 4222353 (1980-09-01), Abe et al.
patent: 4302156 (1981-11-01), LaFlame
patent: 4550695 (1985-11-01), Kikuchi et al.
patent: 5025906 (1991-06-01), O'Neil et al.
Bierbrauer Franz A.
Kuttler Wolfgang
Martin Hans
Wichtl Rudolf
Behr GmbH & Co.
Foley & Lardner
Solak Timothy P.
Thorpe Timothy S.
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