The present invention relates to a drainage or discharge valve for the emptying and flushing of toilets or urinals etc. in a vacuum sewage system, such system including beyond the valve, one or more tubular collectors or suction pipelines connected at their outlet ends to one or more vacuum generators.

Vacuum sewage systems of the above-mentioned kind are commonly known and dominating in connection with the use onboard ships, aero planes and trains. However, on land such systems are also increasingly used and the background for such increased use is primarily the reduced use of water and easy handling and treatment of waste water, as well as the flexible system as regards installation of the pipes given by such system.

The applicant of the present application introduced in 1987, cf. EP patent No. 0 287 350, a novel vacuum sewage system where the vacuum in the system is generated by means of a liquid ring screw pump and where the pump is used as well to discharge the sewage from a vacuum tank to which it is connected.

EP patent No. 0 454 794, also filed by the applicant, further shows a revolutionary improvement of a vacuum sewage system where the liquid ring pump is provided with a grinder and is connected directly with the suction pipe of the system, whereby vacuum is generated in the sewage suction pipe and sewage is discharged directly from the system by means of the pump.

Drainage water from toilets etc. contains particles such as human excrements and paper and it is therefore important that valves of the above mentioned type is designed such that the particles do not build up in the valve housing or components such that the valve loses its function and reliability. It is further important that said type discharge valves are simple and cheap to produce and use, that they open and close speedily, are sufficiently sealed towards the surroundings, are long lasting and that they create little noise when the toilet is flushed (discharged).

With one of the most common discharge valves in the market which is shown in FR patent application No. 2.366.186 a solution is applied which is based on a flexible flow through section or body, designed to be squeezed flat by a spring device when being closed and held apart by the vacuum of the system when being opened. This known type of valve is only partly fulfilling the above-mentioned requirements as the life time of the valve is relatively short due to the flexible body being worn out and since it requires frequent maintenance and repair. Besides, the valve is relatively noisy due to slow opening and closing function.

With the present invention is provided a discharge valve for toilets etc. in vacuum sewage systems that fulfil to a large degree all of the above-mentioned requirements.

The invention is characterized by the features as defined in the attached independent claim 1.

Advantageous features of the invention are further defined in the attached dependent claims 2 - 9.

The invention will be further described in the following by way of examples and with reference to the drawings where:

Fig. 1 shows a perspective view of a discharge valve according to the invention including a top view of a toilet in much smaller scale in which the valve is connected and push-button, starter device initiating the flushing (starting) operation of the valve,

Figs. 2 - 3 shows, in a bit larger scale, a cross section (the same cross section), of the valve shown in Fig. 1 , where in Fig. 2 the valve is closed and in Fig. 3 the valve is open,

Fig. 4 shows another cross section of the discharge valve showing the control device for the flushing of a toilet or the like where the valve is in an open discharge position.

Referring to Figs. 1 and 2, the discharge valve according to the present invention is of the gate valve type with a gate valve body 24 driven by means of a piston 36/membrane

18 device on the basis of vacuum from a vacuum source, preferably the system itself. Fig. 1 shows as stated above a perspective view of a discharge valve 1 according to the invention. Fig. 1 further shows, in smaller scale, a toilet 3 onto which the valve is intended to be connected, as well as a push button starter device 2 designed to initiate opening of the discharge valve and flushing of the toilet. The valve is provided with an outlet pipe stub 65 to be connected to tubular collectors or suction pipelines (not shown) being in turn connected to vacuum sources such as vacuum tanks or vacuum pumps etc.

The discharge valve 1 as shown in Fig. 1 includes as is further shown in Fig. 2 a valve housing comprising a lower valve housing part 13 with a flow through opening 26 (see Fig. 3) and valve gate seat 27, and an upper valve housing part 28 onto which is provided a first control device 4 for opening the discharge valve and a second control device 5 for the control of the flushing of the toilet 3.

The gate valve body 24 is, at its lower end, provided with a sealing body 11 attached to the valve body 13 by means of a "hook lock means" 31. The valve body 24 with the sealing body 11 is held in position against the valve seat 27 by means of a helical spring

19 provided in a hollow space 32 of the valve body 24 between an inner spring seat 33 in the valve body 24 and a valve body guide 25 along which the valve body 24 is movably provided. The packing body 11 forms part of a membrane skirt 34 which is sealably attached to a membrane flange 35 in the lower housing part 13. Thus, with this sealing body 11 and membrane 34 arrangements the flow through area 26 of the valve is sealed off from the upper housing space 23.

As stated above the gate valve body 24 is driven by means of a piston 36/membrane device provided within the upper housing space 23. The piston 36 forms part of the valve body 24 and stretches outwards within the upper housing space 23. The outer end of the piston 36 is provided with a circular flange 37 onto which the inner part of the membrane 18 is sealably attached. The outer part of the membrane 18 is provided with a packing element 38 which is attached (squeezed) in a sealing manner between the upper and lower housing parts 28, respectively 13. On the other hand the two housing parts 28, 13 are attached to one another by means of a "hook lock means" 39 (not further shown). The upper chamber 23 is connected to a vacuum source, preferably to the suction pipeline of the vacuum system as shown in Figs. 1 and 2, via a bore or conduit 15 and vacuum connection tube 12, and to the atmosphere via another bore or conduit 17. With the piston 36 and membrane 18 arrangement is provided a reliable and frictionless driving means which reacts speedily whereby the opening and closing time of the valve is reduced quite notably compared to the known discharge valve solutions. The reduced opening and closing times reduces the valve noise vastly and represents as such an important advantage with the present invention.

As stated above and as shown i Figs. 1 and 2, a control device 4 for controlling the opening and closing of the discharge valve is provided on the upper housing part 28. The control device 4 includes an atmosphere air intake valve 9 and a vacuum source valve 10 which are operated by a double piston 22, 42 arrangement provided within the device 4 housing 40. Each of the pistons 22, 42 are held apart by means of a helical spring 41 provided in an open chamber 43 between the two pistons 42, 22 as shown in Fig. 2 and Fig. 3. Further, each of the pistons 42 and 22 are axially guided by means of cylindrical extensions 45, 46 provided in a movable manner within corresponding openings or bores 47, 48 in the control housing 40. The outer ends of the extensions 45, 46 are in turn each provided with a respective valve closure discs 58, respectively 59 which are adapted to rest against corresponding valve seats 60, 61. A chamber 43 defined between the pistons 22, 42 is provided with a pipe stub 49 to be connected to a hose or the like providing linkage to a vacuum source via the starter device 2 shown in Fig. 1 (see later description of function).

Even though the discharge valve 1 controlled by the abovementioned control device 4 and is driven by means of vacuum, the valve may be operated manually by means of downwardly from the piston 36 protruding knobs 21 extending through openings in the lower housing 13. When there is a need to open the valve manually, the knob 21 is pressed upwards and the valve body 24 with the packing body 11 is as well thereby lifted upwards from the valve seat 27.

As further stated above and as shown in Figs. 1 and 4, a flush control device 5 for the opening and closing of fresh water for the flushing of the toilet 3 is provided as well on top of the upper valve housing part 28. The flush control device is shown in more detail in Fig. 4 and includes, within a flush control housing 50 provided flush valve 57 with a seat valve body 51 being driven by means of a piston 52 via a trigger arm 53. The piston is, on the opposite side of the connecting point 54 for the trigger arm 53 provided with a helical spring 55, whereby the piston is pressed downwards and the seat valve body 51 is pressed against the seat 56 such that the flush valve 57 is closed when the toilet is not in operation. The piston 52 is driven by vacuum from a vacuum source by evacuation of air from a piston chamber 64 via a hose 8 (see Fig. 1) from the starter device 2 (cf. later section). The flush valve 57 is provided with a water connection inlet 62 to be connected to a water supply (not further shown) and water outlet 63 to be connected to a water supply tube to the toilet (neither not shown). The discharge valve according to the invention functions as follows: Whenever the toilet is used and the content in the toilet bowl needs to be discharged, a button (not shown) on the starter device 2 (see Fig. 1) is pushed in and opens for vacuum from the discharge line 22/vacuum hose 12 to the control valve 4 via vacuum tube 6 and 7. The discharge valve is at this time closed and the gate valve body 24 with the packing body 11 is in a lower closed position as shown in Fig. 2. Air is now, as the starter button is pushed, immediately evacuated from the chamber 43 of the control valve 4 whereby the pistons 42, 22 will move towards one another and the atmosphere air intake valve 9 is being closed while and a vacuum source closure valve 10 is opened. Air form the upper membrane chamber is then evacuated via the vacuum bore 15 and at the same time air is evacuated from the space between the packing body 11 and gate valve body 24 such that the packing body contracts (shrinks) to eliminate friction between the packing body and the valve seat 27 and through-flow opening 26 (see Fig. 3). The seat valve body now opens speedily to a full open position as shown in Fig. 3 and the content of the toilet is evacuated through the opening 26 (not further shown).

At the same time as the gate valve body 24 opens, air is evacuated from the piston chamber 64 of the flush control device 5 through the vacuum tube 8 (see Fig. 1) whereby the piston 52 opens the water flush valve 57 via the power arm 53 and flushing of the toilet is initiated.

The opening time for the gate valve body 24, i.e. the time camber 43 of the control device 4 is subjected to vacuum, is preset by the starter device 2, not further explained) to ensure complete emptying of the toilet, usually 3 - 4 seconds. Once the starter device 2 cuts off the vacuum to the chamber 43, the pistons 42, 22 of the control device are move outwards by the helical spring 45 whereby the vacuum source valve closes while the air evacuation valve 9 opens to evacuate air from the upper chamber 23 of the discharge valve 1. The helical spring 19 forces the gate valve body 24 with the piston 36 downwards to a closing position as shown in Fig. 2. Simultaneously the packing body 11 expands returning to its original shape as air again enters the space between the packing body and gate valve body through the air opening 16, thereby tightly pressing against the valve seat 27 sealing off the flow-trough area 26 of the valve.

The water flushing valve 57 is still open 5 - 6 seconds after the closing of the discharge valve. Thereafter the vacuum is cut off by the starter device 2 (Fig.1 - function not further shown or explained) and the piston 52 of the flushing control device 5 is forced downwards displacing the power arm 53 which in turn forces the valve body 51 towards the valve seat 56 and thereby closing off the water supply.

The discharging and flushing function is hereby ended and the discharge valve is ready for a new discharging and flushing operation.