Abstract:
A flushing device includes a cistern, in which at least one pressure chamber is arranged with a supply line for water and a discharge valve. At least part of the flushing water may be pressurised in the pressure chamber and may be discharged for flushing through the discharge valve. At least one pressure cylinder unit is provided, in which the flushing water may be pressurised and discharged for flushing, by means of a spring-loaded pressure piston. The pressure piston is preferably held in a starting position and may be released for a flushing execution. Should two pressure cylinder units be provided, either a partial or a complete flushing operation may be selected.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a flushing device for a lavatory, having a flushing cistern in which is arranged a pressure vessel, which has a feed line for water and a discharge valve and in which at least some of the flushing water can be subjected to pressure and can be discharged through the discharge valve for flushing purposes. 
   2. Description of the Related Art 
   Conventional flushing cisterns have, as discharge valve, a float valve which is opened, for the purpose of triggering a flushing operation, for example by the actuation of a button. The flushing cistern is arranged above the toilet bowl which is to be flushed and, when the float valve is opened, the flushing water flows, as a result of the gravitational force, through a flushing pipe into the toilet bowl. However, flushing devices in the case of which the flushing water is subjected to pressure in the flushing cistern are also known. During flushing, the flushing water, as a result of the increased pressured, leaves the flushing cistern with an increased amount of energy and, correspondingly, the flushing action is greater. 
   For example, WO 98/39522 discloses a flushing cistern with a pressure vessel which has a base with a flushing valve. To prepare for a flushing operation, water from a supply line is introduced into the spherical pressure vessel. In addition, air is fed to the pressure vessel. This air is compressed when the water is introduced and builds up a pressure in the vessel. If the flushing valve is opened, then the water flows out of the pressure vessel as a result of the expanding air and, on account of the gravitational force, flows through the open flushing valve into the toilet bowl. As a result of the enhanced flushing action, less water can be used for flushing. The disadvantage with this flushing device is that it has to be designed for a comparatively high pressure, and that it is difficult to set the appropriate pressure in the vessel. 
   The applicant&#39;s WO 95/04196 discloses a flushing device which has a flushing cistern with two water outlets. Through one outlet, of the flushing processes, water is introduced as usual into the toilets bowl. The other outlet is connected to a nozzle which is arranged in a siphon of the toilet bowl and is intended to accelerate the water of the siphon during flushing. The flushing water is not subjected to pressure in the case of this flushing device. A flushing device with two outlets and a nozzle in the siphon involves comparatively high outlay and is not suitable in all cases. 
   SUMMARY OF THE INVENTION 
   The object of the invention is to provide a flushing device of the abovementioned type which generates less noise and can be adapted to different toilet bowls. The flushing device according to the invention is characterized by at least one pressure-cylinder unit in which flushing water can be subjected to pressure and can be discharged by way of a spring-loaded pressure piston for flushing purposes. In the cases of the flushing device according to the invention, rather than air being compressed, a spring is subjected to stressing. This has the significant advantage that the flushing capacity can be easily optimized, and adapted to specific toilet bowls, by a corresponding setting of the spring or by additional weights. 
   According to a development of the invention, it is provided that the pressure piston is locked in a starting position and can be unlocked for flushing purposes. This results in a precisely defined flushing quantity and in a pressure piston subjecting the flushing water to a defined pressure during flushing. 
   The pressure piston can be unlocked mechanically, pneumatically or electrically. 
   According to a development of the invention, it is provided that the pressure-cylinder unit accommodates essentially all the flushing water. A pressure-cylinder unit may be integrated in a very space-saving manner in a cistern body. It is preferably provided that the pressure-cylinder unit is formed, at least in certain regions, by an outer wall of the flushing-cistern body. This allows particularly space-saving and cost-effective production. 
   According to a development of the invention, it is provided that the discharge valve is a servovalve. According to a development of the invention, such a valve may have a diaphragm, which closes the valve under water pressure. This allows flushing to take place essentially without any closing noise. 
   If the servovalve has an air-extracting member, then flushing can be triggered by this member being actuated. Such triggering is comparatively straightforward and can take place mechanically, pneumatically or electrically. 
   If the flushing device has two pressure cylinders which are arranged in the flushing cistern, then two different types of flushing are possible. In the case of a half flush, only one of the two pressure-cylinder units is emptied. For a full flush, both pressure-cylinder units are emptied at the same time. The quantity of flushing water is precisely defined in both cases. The two pressure-cylinder units may have the same quantity, or different quantities, of flushing water. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An exemplary embodiment of the invention is explained in more detail hereinbelow, with reference to the drawing, in which: 
       FIG. 1  shows a three-dimensional view of a flushing device, part of which has been cut away, 
       FIG. 2  shows a three-dimensional view of the flushing device according to the invention, 
       FIG. 3  shows a section along line III—III from  FIG. 1 , 
       FIG. 4  shows a vertical section through the flushing device according to the invention, individual parts having been omitted for technical reasons, 
       FIG. 5  shows a section according to  FIG. 4 , but following partial flushing, and 
       FIGS. 6 and 7  show sections through the discharge valve. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The flushing device has a flushing cistern  1 , which has a cistern body  2  preferably produced from plastic. This cistern body  2  has a top wall  2   a , a base wall  2   b  and a casing  2   c . An inspection opening  10  is arranged on the front side, although it is also possible for this opening to be arranged in the top wall  2   a . Located in the bottom region of the casing  2   c  is a discharge connector  21 , which is connected to a toilet bowl (not shown here). The discharge connector  21  leads horizontally into the toilet bowl. 
   The cistern body  2  contains two pressure-cylinder units  8  and  9 , which each have a respective piston  11 ,  12 . The pistons  11  and  12  can each be displaced vertically in a respective pressure chamber  14 ,  15  and are sealed by sealing rings  13  in relation to a respective cylinder wall  41 ,  42 . These walls  41  and  42  each have a respective base  18 ,  19 , in which a respective through-passage  16 ,  17  is arranged. These through-passages  16  and  17  lead into a common chamber  20 , in which a discharge valve  27  is arranged. The discharge valve  27  is a servovalve and has, as closure body, a bellows  44  comprising a flexible diaphragm. The bellows  44  interacts with a valve seat  43  arranged on the discharge connector  21 . As, for example,  FIG. 6  shows, the bellows  44  is connected to an air-extraction channel  33 , from which air can be extracted by means of an air-extraction member  31 . For this purpose, a closure element  34  is raised from a valve seat  36  of the air-extraction channel  33  counter to the restoring force of the spring  35 . This can take place, according to  FIG. 5 , by way of a cable pull  45 . It is also conceivable, however, to use some other actuating mechanism. For example, the closure body  34  can be raised pneumatically or by an electric drive. Remote triggering is also conceivable. 
   The bellows  44  also forms an inner chamber  40 , which is always connected to the chamber  20  via a through-passage  28 . The chamber  40  is connected via a water line  7 , according to  FIG. 7 , to an inflow valve  6 , which has a regulating valve  5  arranged upstream of it. This regulating valve  5  is connected to a supply line  4 . When the inflow valve  6  is open, the inner chamber  40  is connected to the supply line  4 . 
   The pistons  11  and  12  are each provided, on the top side, with a pin  23  which is directed vertically upward and interacts with a securing means  24  in each case in order to arrest the piston  11 ,  12 . The securing means  24  each have a bearing  25 , on which locking means  26  are fitted. These locking means  26  may be used to lock the pistons  11  and  12  in a releasable manner in the top, starting position, which is shown in  FIG. 4 . The locking means  26  are designed such that the pistons  11  and  12  are locked automatically when they reach the starting position. The locking is released by means of an unlocking device  30 , which is in engagement with the locking members  26 . Unlocking takes place, for example, by a horizontal movement of the locking pin  26   a  counter to the restoring force of a spring  26   b.    
   Supported on each of the bearings  25  is a compression spring  22 , which butts, at a bottom end, against the piston  11 ,  12 . If the piston  11 ,  12  in the bottom position, which is shown on the left in  FIG. 5 , is raised, then the corresponding spring  22  is subjected to stressing. Once the top position has been reached, then the piston  11 ,  12  is automatically locked. 
   The operation of the flushing device  1  according to the invention is explained in more detail hereinbelow. 
     FIG. 4  shows the flushing cistern  1  in the starting position. The two pressure chambers  14  and  15  are filled with flushing water. The springs  21  are subjected to stressing and the pistons  11  and  12  are locked in a top, starting position. The discharge valve  27  and the air-extraction valve  31  are closed. The inflow valve  6  is likewise closed. 
   In order to trigger a partial flushing operation, in the case of which flushing takes place, for example, with three liters of water, the unlocking device  30  is activated, by virtue of the button  32   a  which is shown in  FIG. 5  being pushed, such that the catch  26   a  of the pressure-cylinder unit  8  is displaced and the piston  11  is thus unlocked. The piston  11  is thus freed and subjected to loading by the force of the spring  22 . At the same time as the cap  26   a  is displaced, the closure body  34  of the air-extraction valve  31  is raised by way of the cable pulll  45 . As a result, the pressure in the chamber  40  drops and the difference in pressure in relation to the chamber  20  causes the bellows  44  to be raised off from the valve seat  43 . The water in the chamber  20  can thus flow through the discharge connector  21  into the flushing pipe (not shown). Since, as has been mentioned above, the chamber  20  is connected to the pressure chamber  14  via the opening  26 , this outflowing water is subjected to pressure by the piston  11  and/or the spring  22  as it is relieved of stressing. The piston  11  moves downwards into the position which is shown in  FIG. 5 , flushing water is simultaneously being discharged out of the chamber  14 , through the chamber  20  and the discharge connector  21 . The water here, according to  FIG. 6 , flows horizontally, in the direction of the arrow  46 , into a flushing bend (not shown here) or directly into the flushing channel of a lavatory bowl. Such direct horizontal introduction of flushing water into the toilet bowl is advantageous since no energy is lost by deflection around a bend. 
   If the piston  1  is in the position which is shown in  FIG. 5 , then the flushing operation is at an end. Remaining in the chamber  20  is by the residual water  39 , shown in  FIG. 7 , which is connected to the water in the chamber  40  via the through-passage  28 . When the chamber  20  is emptied, air is drawn in out of a chamber  3  via the air-extraction valve  29 . The drop in pressure in the chamber  40  causes the inflow valve  6  to open automatically, and the supply line  4  is thus connected to the line  7 . Water thus flows through the line  7  into the chamber  40 , and via the through-passage  28  into the chamber  20 . The air present in the chamber  20  is displaced into the chamber  3  by the air-extraction valve  29 . If the chamber  20  has been filled with water, then this water passes through the through-passage  16  to the piston  11  and moves the latter upwards, on account of the water pressure, counter to the restoring force of the spring  22  until it butts against the bearing  25  and is locked. If a predetermined cistern pressure has been reached, then the regulating valve  5  closes the filling valve  6 . The piston  11  is thus in the starting position again and both pressure chambers  14  and  15  and the chamber  20  are filled with water. Even as the refilling operation is initiated, the bellows  44  moves into the closed position on account of the increasing pressure in the chamber  40 , and thus butts against the valve seat  43 . Once air initially present in the chamber  20  has been displaced, the air-extraction valve  29  closes on account of the buoyancy of a float  29   a  in the water. The system pressure in the refilled flushing cistern is, for example, and preferably, approximately 0.2 bar. 
   For a further flushing operation, then, it is possible to make a selection between partial flushing, in the case of which merely the pressure chamber  14  is emptied, and full flushing, in the case of which the pressure chamber  14  and the pressure chamber  15  are emptied. Full flushing may be triggered using the button  32   b  ( FIG. 5 ). If this button  32   b  is actuated, then the unlocking device  30  unlocks both pistons  11  and  12  at the same time. These move downward and displace the water out of the pressure chambers  14  and  15 . Since the air-extraction device  31  is actuated at the same time via the cable pull  45 , the discharge valve  27  opens and the water is discharged horizontally, in the direction of the arrow  46 , through the discharge connector  21 . Since both pressure chambers  14  and  15  are emptied, the quantity of water discharged is double the quantity for the partial flushing explained above. The refilling operation takes place essentially as has been explained above. In the event of a drop in pressure, the inflow valve  6  thus opens automatically and water flows, via the line  7 , into the chamber  40  and, through the through-passage  28 , into the chamber  20 . Once the air in the chamber has been displaced and the air-extraction valve  29  has been closed, then, as a result of the water pressure, both pistons  11  and  12  are raised at the same time and moved into the locked, starting position. When the system pressure is reached, the upstream regulating valve  5  closes the inflow valve  6 . The flushing cistern  1  is thus ready for a further flushing operation. The flushing device, as has been explained, has the advantage that it can be optimized and adapted to specific toilet bowls. For this purpose, it is possible, for example, for the springs  22  to be exchanged for stronger or weaker springs. In addition, it is possible, for example, for annular weights  47  to be positioned on the pistons  11  and  12  according to  FIG. 5 . Such weights  47  increase the pressure of the water in the pressure chambers  14  and  15  and, correspondingly, these pressure chambers  14  and  15  are emptied under higher pressure, and correspondingly more quickly, during flushing. The regulating valve  5  is adapted to this modified cistern pressure.