COMBINED FAN AND VALVE

Abstract: A combined fan and valve for evacuating air from a space, especially in connection with ventilation of a toilet bowl from odoureous air. The fan wheel (8) of the fan is assembled with a sealing membrane (13). Moreover, the hub (10) of the fan wheel is provided with spindle threads (11) for cooperation with corresponding spindle threads (7) on the output shaft of the drive motor (5). When the motor is started, the fan wheel is lifted from the valve seat and pumps air from the space through the inlet (2) and out through the outlet (3). When the motor stops, the fan wheel will screw itself downwards along the screw (7) under the influence of the gravity in order to bear against the valve seat (4).

Description: COMBINED FAN AND VALVE Technical Field The present invention relates to the technical field of ventilation means, especially for a water-closet, as described in the Swedish patent sp cification No. 7904292-5. Background Art In said patent Specification is described a ventilation means for evacuating of odoureous air from the bowl of the water-closet through an internal fan system for discharging to the sewer pipe of the toilet. The fan system comprises a non- return yalve, which however is difficult to con- struct so that it operates well. The fan system must not be dimensioned so that it gives a too high over-pressure in the sewer pipe. As a matter of fact it is desirable that the non-return valve should operate at such a small pressure difference as 5 mm of water. Of obvious reasons it is impor¬ tant that the non-return valve has an adequate sealing in the closed posi- tion. We have found it difficult to make a satisfactory operating non-return valve. More specifically, the present invention relates to a combined fan a valve for evacuating of air from a space. The combined fan and valve compris a housing having an inlet and an outlet and a fan wheel and a drive shaft. B means of the combined fan and valve according to the present invention, the above mentioned problem is solved. In US patent specification No. 4, 133., 060 a combined fan and valve is described, where the fan wheel as well as the valve body are affected by the rotation of the drive shaft. When the shaft rotates, the yalve body is lifte from its valye seat by means of a centrifugal device and links. However, thi device requires that the shaft rotates in order that the centrifugal device shall lift the yalye body. Thus, friction will arise at the connection point between the links and the yalve body, which due to the fact that it bears upon the yalye seat is immobile, which requires that the driye motor must have quite a high starting force. A motor having a low starting force can 2 hardly be used in this construction. Moreoyer, the link means is a potential source of failure and requires maintenance. It is an object of the present invention to provide a fan having a valve, which has a satisfactory sealing in the closed position, but still can be safely opened at the yentilation. . Moreover, it is an object of the invention to provide a ventilation me which can be driven by a simple and weaR low voltage motor without any majo power consumption, and which is simple to manufacture, has few integral par and is simple to maintain. Disclosure of the Invention This is provided according to the invention by means of the fact that fan wheel is assembled with a sea ing membrane for sealing against a valve seat in the housing. -Moreover, the fan wheel is provided with threads havin a high pitch for cooperation with corresponding threads on the drive shaft. the drive shaft is standing still, the fan wheel and the sealing membrane a forced against the valye seat. However, when the drive shaft rotates, the f wheel and the sealing membrane are lifted from the valve seat by means of said threads in order to open the valve and allow the fan to evacuate air f said space. Preferably, the fan wheel and the sealing membrane are forced to co operation with the valve seat.by means of the gravity, but this operation c also be performed or helped by means of a spring. Preferably, said threads are spindle threads having such a high pitch, that the friction forces are overcome by means of the gravity, such that the fan wheel is forced, upon still-standing drive shaft, to the position where the sealing membrane bear against the valve seat. Eventually, the fan wheel can operate one or several micro switches at least one of its end positions, for operating other equipment. Brief Description of the Drawings For the purpose of exa plificat on, a preferred embodiment of the i vention is described below with reference to the appended drawings. Fig. 1 a sectional view of the combined fan and valve according to the invention. Best Mode for Carrying Out the Invention and Industrial Applicabili The combined fan and yalye as shown in Fig. 1 comprises a fan housi l having an inlet 2 and an outlet 3. The inlet 2 forms a yalye seat 4 in th fan housing. An electric .motor 5 of a low*yoltage type is adapted at the fa housing, and the drive shaft 6 thereof extends to the interior of the fan housing. At the drive shaft 6, a screw 7 is arranged having spindle threads Moreover, the fan housing 1 comprises a fan wheel 8 having several fan blades 9. The fan wheel i hub 10, which comprises a nut 11 haying spindle threads corresponding to the spindle threads of the screw 7. A sealing body 12 having a sealing membrane 13 is attached to the 7 fan wheel 8 between the fan plates 9 and - the hub 10. The hub 10 comprises a downwardly closed sleeye 14, which closely clamps the sealing -membrane against the hub 10. The sleeve 14 has a length which is sufficient to allow the screw 7 to freely enter the sleeve 14. The operation of the combined fan and valve will be described below in detai.l. In Fig. 1 there is shown the initial position having the drive shaft 6 standing still and the sealing membrane 13 cooperating with the valve seat 4. No air can pass backwards fromthe outlet 3 to the inlet 2 and the yalve normally seals also against air flowing from the inlet 2 to the out¬ let 3. However, if there is a great pressure difference between the inlet 2 and the outlet 3, the fan wheel 8 will be lifted to a certain extent and pass the air in order to equilibrate the over-pressure. When the motor 5 is started by means of supplying a voltage through the wires 15, the screw 7 will start to rotate. Since the sealing member 13 bears against the valve seat 14, this fact partly prevents the fan wheel 8 from, rotating, which results in that the hub 10 and the nut 11 will screw itself upwards along the screw 7. However, due to the friction between the screw 7 and the nut 11, the fan wheel 8 will start to rotate together with the screw, and air is pumped from the inlet 2 to the outlet 3. The fan wheel 8 positions itself at a certain height along the screw 7 in dependence of the work performed by the fan wheel 8. If the fan wheel 8 performs a hard work, the fan wheel will rise up to the upper end of the screw, but if fan wheel 8 σnly needsto perform a smaller work, the fan wheel will be positioned lower along the screw 7. This position is obtained, automatically. The power of the motor 5 and the pitch of the spindle threads 7 and 11, and the weight of the fan wheel 8 are matched so that the intended operation is achieved. When the fan wheel 8 rises along the screw 7, the lower end of the screw will enter inside the sleeye 14, which howeyer, allows this entrance without any obstacle. Not until the fan. wheel 8 approaches the upper end of the housing, the lower end of the screw 7 will engage the closed end of the sleeye 4 and preyent that the fan wheel 8 reaches the upper wall of the housing. OM? When the motor 5 stops due to the fact that the supply of electri c current through the wi res 15 is disconnected, the output shaft 6 and the screw 7 wil l stop to rotate. When the output shaft 6 stands completely still , the fan wheel 8 wil l continue to rotate downwards along the screw 7 due to the fact that the gravity overcomes the fri ction in the spindle threads 7 and 11. Final ly, the fan wheel reaches the position shown in Fig. whereupon the sealing body 12 and the sealing membrane 13 bears against the valve seat 4 and performes a seal ing. The sleeve 14 seals agai nst the hub 1 and sealing -membrane 13 so that no air can pass through the somewhat leaky spindle threads between the screw 7 and nut 11. The fan wheel 8 can be adapted to operate micro switches 16 in the lower position and also in the upper position , as is suggested by broken lines in the f gure . The sleeve 14 can at ts lower end be provi ded with a micro switch, whi ch disconnects all supply of current to the motor 5 as soon as the screw 7 touches the mi cro switch , since it is a malfunction if the screw 7 reaches the bottom of the sleeve 14. The invention- can of course be modified and amended i n many ways within the scope of the invention. Thus, the radial fan wheel 8 can yery well be repl aced by an axial fan. The spindle threads in the screw 7 and nu 11 can be right hand threads or left hand threads in dependence of the • rotational direction of the motor 5 and the direction of the fan blades . A spring 17 can be adapted to force the fan wheel 8 to its rest posi¬ tion in order to assist the gravity if so is needed, whereby threads having less pitch can be used. If i t is required that the fan wheel is mo nted at an horizontal axis, the spring wil l ful ly replace the gravity. If a conventional electric motor of a low-vol tage type is used, the output shaft 6 wi ll brake quite heavily when the voltage is disconnected. This entai ls that the fan wheel 8 wi ll rotate downwards along the screw 7 due to the fact that the mass forces of the fan wheel 8 tends to maintain its rotation. By this fact the sealing membrane 13 will be placed quite heavi ly against the seat 4 and a close seal is obtained. The combi ned fan and yalye according to the inyention can be used at other applications where evacuati ng of ai r or gas is required, such as in a ki tchen fan, whi ch is driven intermittently. Moreover, the inventi on can be used for provi ding air to an oi l burner. In this application the micro switches operates the remaining components of the oil burner. A person ski lled in the art realizes that the invention can be modi¬ fied in many ways within the scope of the invention. The invention is only limited by the appended cl aims.

Claims: CLAIMS 1. A combined fan and yalve, comprising a fan housing haying an inlet and an outlet, a fan wheel and a drive shaft, c h a r a c t e r i z¬ e d in that the fan wheel (8) is adapted to seal against a valye seat (4) positioned in the housing (1); and that the fan wheel is provided with a thread (11) for cooperation with a corresponding thread (7) on the drive shaft (6), such that when the drive shaft is standing still, the fan wheel is forced against the valve seat, and when the drive shaft is rotating, the fan wheel- is lifted from the valve seat by means of said threads in order to open the valve. 2. A combined fan. and valve according to claim 1, c h a r a c- te r i z e d in that the fan wheel (8}, when the drive shaft is standing still, is forced against the valve seat (4) by means of the gravity in¬ fluence on the fan wheel or by means of a spring force. 3. A combined fan and valve according to claim 1 or 2, c h a r a c- te i z e d in that the fan wheel (8) comprises a sealing membrane (13) for sealing against the valve seat (4). 4. A combined fan and valve according to claims .2 or 3, c h. a r a c te r i z e d in that said threads (7, 11) are spindle threads having such a high pitch that the frictional forces in the threads are overcome by the gravity or the spring force. 5. A combined fan and valve according to any one of claims 1 to 4, c h a r a c t e r ! z e d in that the fan wheel (8) is adapted to operate a micro switch (16) or similar in at least one of its end positions. O PI

Inventors: MAGNUSSON PER ERIK
Applicants: LAGERSTEDT & KRANTZ AB, MAGNUSSON PER ERIK
Application year: 1982
Main classification: E03D9
IPC codes: E03D9, F04D25, F04D29, F24F7