Vacuum Toilet With Centrifugal Separator

Abstract

The invention relates to a vacuum toilet, comprising a toilet bowl with a bowl outlet opening, an intermediate tank with an inner wall surface enclosing an interior of the intermediate tank, an inlet opening formed on the intermediate tank, an outlet opening formed on the intermediate tank for connecting the interior of the intermediate tank to a wastewater container, a vacuum generator in fluidic communication with the interior of the intermediate tank for generating underpressure in said interior of the intermediate tank, a wastewater feed line which connects the bowl outlet opening to inlet opening and a wastewater tank which is in fluidic communication with the interior of the intermediate tank via the outlet opening. According to the invention, the inner wall of the intermediate tank, in at least one surface section, is formed in a rotationally symmetrical manner about an axis, and the inlet opening is arranged in said at least one surface section and has an orientation which defines an in-flow direction having a directional component tangential to said axis.

Description

[0001] The invention relates to a vacuum toilet, comprising a toilet bowl with a bowl outlet opening, an intermediate tank with an inner wall surface enclosing an interior of the intermediate tank, an inlet opening formed on the intermediate tank, an outlet opening formed on the intermediate tank for connecting the interior of the intermediate tank to a wastewater container, a vacuum generator in fluidic communication with the interior of the intermediate tank for generating underpressure in said interior of the intermediate tank, a wastewater feed line which connects the bowl outlet opening to inlet opening and a wastewater tank which is in fluidic communication with the interior of the intermediate tank via the outlet opening.

[0002] Vacuum toilets of the aforementioned type are specifically preferred in vehicles, for example in buses, trains, airplanes and ships. Due to the cramped installation conditions that often prevail in such situations, and the absence of any differences in height, it is not possible for wastewater to be reliably discharged from the toilet bowl purely under the force of gravity. The wastewater is therefore drawn out of the toilet bowl by a vacuum and conveyed into a wastewater tank.

[0003] Central vacuum systems, so called, in which a vacuum is applied to the wastewater tank and the wastewater can then be conveyed out of the toilet bowl into the wastewater tank via a switched valve in the wastewater pipe, are known from the prior art. However, the disadvantage of this solution is that a high vacuum is necessary, and that the wastewater tank must be designed to withstand the vacuum. It is generally desirable to operate the wastewater tank at atmospheric pressure to allow the wastewater tank to be of rugged construction to suit the cramped construction space on board vehicles.

[0004] Vacuum toilet systems with an intermediate tank which is connected between the toilet bowl and the wastewater tank in the direction of wastewater flow are also known from the prior art. In these vacuum toilets, an underpressure is firstly generated in the intermediate tank before the intermediate tank is then connected to the toilet bowl and the wastewater is conveyed into the intermediate tank. The connection to the toilet bowl is subsequently closed. Overpressure is then applied to the intermediate tank and the wastewater is conveyed out of the intermediate tank into the wastewater tank. Although these vacuum toilet systems allow the wastewater tank to be operated under atmospheric pressure, they require a substantial number of control valves to prevent wastewater entering the underpressure conduits and the vacuum generator, and in order to carry out the sequence of underpressure and overpressure.

[0005] The object of the invention is to provide a vacuum toilet system and a device for discharging wastewater from a toilet bowl, which allow reliable operation with uncomplicated apparatus.

[0006] This object is achieved, according to the invention, with a vacuum toilet designed as described at the outset, in which the inner wall of the intermediate tank, in at least one surface section, is formed in a rotationally symmetrical manner about an axis, and the inlet opening is arranged in said at least one surface section and has an orientation which defines an in-flow direction having a directional component tangential to said axis.

[0007] According to the invention, the wastewater is conveyed from the toilet bowl into the wastewater tank via an intermediate tank. To that end, a vacuum is applied to the intermediate tank, and the wastewater is conveyed by this vacuum from the toilet bowl into the intermediate tank. According to the invention, the wastewater is fed into the intermediate tank in such a direction that it flows into a rotationally symmetric section with a tangential directional component. Due to being fed into the tank in this manner, the wastewater is guided by centrifugal forces in a circular motion inside the intermediate tank and runs along the intermediate tank wall. An in-flow direction with a tangential directional component should be understood here to mean an in-flow direction oriented in such a way that the vector defined by that direction can be broken down so that a tangential vector component ensues. The in-flow direction can therefore include a radial or an axial directional component as well. However, it is preferred that the in-flow direction does not include a radial directional component, or only a minimal one, but rather is predominantly tangential in orientation, with an additional axial directional component where relevant. Such an orientation of in-flow into the intermediate tank has proved to be particularly advantageous for guiding the wastewater along the wall of the intermediate tank and through the interior of the intermediate tank to the outlet opening.

[0008] Thus, according to the invention, the wastewater is guided in a defined manner inside the intermediate tank and along the wall thereof. This prevents any increased tendency of the wastewater in the intermediate tank to foam, for example, or to fill out the intermediate tank in an undefined manner by flowing into it in an undefined manner and/or by impacting against the inner wall, from spraying or squirting around inside the intermediate tank, thus damaging the vacuum system and impeding or preventing complete discharge of the wastewater from the intermediate tank.

[0009] A rotationally symmetric cross-section within the meaning of the invention is to be specifically understood as a circular cross-section which allows rotary movement of the wastewater along the inner wall. Only the cross-section of the interior of the intermediate tank is relevant in this regard, whereas the outer shape of the intermediate tank is of no relevance for that particular function and therefore does not need to be rotationally symmetric in shape. The advantages of the invention are already achieved when the rotationally symmetric shape is present in an axially limited section of the intermediate tank in which the inlet opening is arranged, and other axial sections of the intermediate tank have a shape which is not rotationally symmetric. A particularly preferred embodiment, however, is one in which the entire intermediate tank is rotationally symmetric, or at least the region of the intermediate tank between the inlet and the outlet opening has an inner cross-section which is rotationally symmetric. The advantages of the invention are also achieved by cross-sections that deviate from the circular shape, such as oval or elliptical cross-sections, for example, which are also to be understood as rotationally symmetric according to the invention.

[0010] The in-flow direction can basically be defined by the orientation of the inlet opening, i.e. the position and orientation of the cross-section of said inlet opening. According to the invention, however, the direction of flow is defined in a particularly advantageous and reliable manner when the wastewater feed line opens into an inlet passage arranged upstream and/or downstream from the inlet opening in the direction of flow and which defines a direction of flow into the interior of the intermediate tank, said direction defining a directional component tangential to the axis. This development of the invention provides a channel which gives the wastewater flowing into the interior of the intermediate tank a defined in-flow direction. The channel may be tangential in orientation, or may be oriented in a tangential-axial direction, in a tangential-radial direction or have a tangential-radial-axial orientation, wherein the tangential directional component according to the invention is meant to be more strongly pronounced than the axial or the radial directional component. The channel may extend into the interior of the tank or can be arranged outside the inside wall of the tank. By providing a channel, it is possible for the opening into the interior of the tank to be designed flush with the wall of the intermediate tank, thus making it insensitive to adherence of contamination.

[0011] The vacuum toilet according to the invention can be further developed by providing a controllable closure valve in the wastewater feed line. The controllable closure valve may be embodied as an electromagnetically operated valve or as a pneumatically operated valve and in a first switched state allows the wastewater feed line to be closed, and in a second switched position for the wastewater feed line to be opened to produce fluidic communication between the toilet bowl and the intermediate tank. The closure valve is preferably disposed adjacent to and at a small distance from the toilet bowl.

[0012] Another aspect of the invention is a wastewater facility for a vacuum toilet, comprising an intermediate tank with a wall which encloses an interior of the intermediate tank, an inlet opening formed on the intermediate tank for connecting the interior of the intermediate tank to a wastewater pipe, an outlet opening formed on the intermediate tank for connecting the interior of the intermediate tank to a wastewater container, a vacuum generator in fluidic communication with the interior of the intermediate tank for generating underpressure in said interior of the intermediate tank, in which the inner wall of the intermediate tank, in at least one surface section, is formed in a rotationally symmetrical manner about an axis, and the inlet opening is arranged in said at least one surface section and has an orientation which defines an in-flow direction having a directional component tangential to said axis. Such a wastewater facility thus includes the intermediate tank, in the configuration according to the invention, and is suitable for installation in the vacuum toilet without necessarily having to replace the toilet bowl and the wastewater tank. Existing vacuum toilets can therefore be retrofitted in such a way, by installing the wastewater facility according to the invention, that the advantages of the invention are achieved, by removing the intermediate tank already in place and installing the wastewater facility according to the invention. It should be understood, as a basic principle, that the effects and the advantage and the preferred embodiments and configurations of the features of the wastewater facility according to the invention are achieved in the same manner and are to be understood in the same sense as previously described with regard to the vacuum toilet according to the invention.

[0013] The wastewater facility according to the invention can be developed by providing an inlet passage arranged upstream and/or downstream from the inlet opening in the direction of flow and which defines a direction of flow into the interior of the intermediate tank, said direction defining a directional component tangential to the axis. Such an inlet passage, which may be arranged inside, outside, or both inside and outside the interior of the intermediate tank, achieves reliable definition of the in-flow direction with a predominantly or exclusively directional component in the same manner as the inlet channel previously described for the vacuum toilet according to the invention.

[0014] The vacuum toilet according to the invention, or the inventive wastewater facility with an inlet channel, can preferably be developed in such a way that the inlet passage defines the tangential in-flow direction, in particular that the inlet passage runs in a tangential direction.

[0015] In this configuration, an exact tangential in-flow direction into the intermediate tank is defined by the inlet passage, thus achieving a particularly advantageous wastewater flow path inside the intermediate tank.

[0016] The vacuum toilet and the wastewater facility can also be developed by having the axis extend in a direction with a vertical directional component, and preferably with vertical orientation, when the intermediate tank is installed. This orientation of the intermediate tank results in the axis of rotational symmetry of the intermediate tank being vertical or at least substantially vertical. With regard to its circulating flow, the wastewater flowing into the tank can therefore flow in a spiral pattern along the outer wall of the intermediate tank, substantially without disturbance and can continue flowing along the wall in the direction of gravity without detaching from the wall. This arrangement is preferred over horizontal or predominantly horizontal axial orientations, because in the case of horizontally oriented axes the wastewater might detach itself from the wall under the force of gravity, in particular in the upper wall section of the intermediate tank, and would no longer maintain a rotationally symmetric flow along the inner wall of the intermediate tank. In particular when the axis has a vertical directional component, or is vertical, the wastewater can be guided in a spiral movement from an inlet opening provided in the upper region of the intermediate tank to an outlet opening provided in the lower region of the intermediate tank, along the wall of the intermediate tank from the inlet opening to the outlet opening, which means that the wastewater does not perform any uncontrolled movements inside the intermediate tank that might increase the amount of contamination and wastewater discharge.

[0017] It is still further preferred that the inlet opening defines a tangential flow direction, in particular that the inlet opening has a cross-sectional area whose surface normal is tangential to the axis. In this embodiment, a tangential in-flow direction is defined by the inlet opening, thus allowing the path taken by the wastewater inside the intermediate tank to be optimised. It should be understood that such a definition of a tangential in-flow direction is influenced by the path taken by the cross-sectional area of the inlet opening and also by the geometry of the cross-sectional area. For example, a cross-sectional area of oval-shaped cross-section and running flush with the wall of the intermediate tank can produce a tangential in-flow direction and allow the wastewater feed line to be connected in a tangential direction, or for a channel with a correspondingly tangential orientation to be provided.

[0018] The vacuum toilet and the wastewater facility according to the invention can be further developed by the outlet opening having a gravity-actuated closure flap which is moved under the influence of gravity into a closed position, held in said closed position by underpressure when an underpressure in applied to the intermediate tank, and is moved into the open position by the weight force of the wastewater when wastewater lies on a surface of the closure flap facing towards the interior of the intermediate tank.

[0019] In order to create a vacuum in the intermediate tank effectively, it is advantageous and generally necessary in typical designs to close the outlet opening so as to create a barrier between the intermediate tank and the wastewater tank. This barrier can basically be provided by means of a valve, for example a pinch valve, or a valve which is switched pneumatically or electromagnetically and has a sealing member which slides or is moved in some other manner. According to one preferred embodiment according to the invention, the outlet opening is closed by a closure flap which in a first position seals the outlet opening in a closed position under the force of gravity or a spring force. This can be achieved by bringing a circumferential sealing region of the closure flap into contact with a seal seat in the region of the outlet opening. Due to the pressures that are produced at the closure flap when creating a vacuum inside the intermediate tank, an underpressure force acts on the surface of the closure flap facing towards the intermediate tank, whereas atmospheric pressure is exerted on the side of the closure flap facing towards the wastewater tank. As a result, the sealing effect can be beneficially reinforced with increasing underpressure in the intermediate tank, and a seal is produced which allows the closure valve between the intermediate tank and the wastewater tank to be operated in a virtually wear-free manner with minimal actuation force. When the underpressure inside the intermediate tank is removed, the reinforcement of the sealing effect is reduced or cancelled, and the closure flap continues to rest in the closed position solely by the force of gravity or the force of a spring, or a combination of the two. If there is wastewater in the intermediate tank at that time, a water column acts on the surface of the closure flap facing towards the intermediate tank and presses it into the open position, such that the wastewater from the intermediate tank can pass the closure flap and can flow into the wastewater tank. To achieve that purpose, it is advantageous if the weight or spring force that presses the closure flap into the closed position be of such strength that it is less than the weight force of a predetermined residual volume of wastewater that may remain in the intermediate tank after emptying, for example a residual volume corresponding to a water column of 1 to 5 cm, in particular of more than 1 cm and preferably about 2 cm.

[0020] Actuation of the closure flap by the force of gravity can be achieved, for example, by the closure flap being pivotably mounted about an axis and the axis between a counterweight and the closure flap being arranged in such a way that the counterweight actuates a closing movement of the closure flap.

[0021] In the embodiment with the closure flap, it is further preferred that the gravity-actuated closure flap is mounted pivotably about a closure flap axis and has a sealing surface and a weight which presses said sealing surface under the influence of gravity against a sealing face arranged around the outlet opening, or in that the closure flap operated by spring force is pivotably mounted about a closure flap axis and has a sealing surface and a spring element which presses said sealing surface under the force of a spring against sealing surface arranged around the outlet opening. These embodiments allow the closed position to be returned efficaciously from the open position to the closed position, and it is possible to set a closed position in a reliable manner, which can then serve as a starting point for the self-reinforcing sealing effect of the closure flap when creating a vacuum inside the intermediate tank. The weight can preferably be slidingly disposed on a lever arm, in order to set the distance from the closure flap axis and thus to adjust the closure flap in respect of its closing force. The spring used is preferably a helical spring or coil spring which produces a torque about the axis of the closure flap.

[0022] In the case of the embodiments provided with a closure flap, it is further preferred that the closure flap is arranged downstream in the direction of flow from an outlet channel having a cross-sectional area which is smaller than the cross-sectional area of the intermediate tank in the region of the inlet opening. By providing such an outlet channel having a reduced cross-sectional area in comparison with the cross-sectional area of the intermediate tank in the region of the inlet opening, a water column acting on the closure flap is effectively created, with the result that the closure flap is impinged upon by the wastewater with a weight force that efficiently opens it. It is preferred, as a basic principle, that the intermediate tank has a shape having a reduction in the cross-sectional area along a direction extending from the inlet to the outlet opening, for example with a conical geometry tapering towards the outlet opening.

[0023] According to another preferred embodiment, the closure flap has a surface which faces in the closed position towards the interior of the intermediate tank and has a surface normal with a vertical directional component and which is preferably vertical. This configuration of the closure flap and its orientation allows the closure flap to be opened in a particularly effective manner under the force of gravity acting on the wastewater in the intermediate tank, which weighs on the closure flap.

[0024] According to another preferred embodiment, the interior of the intermediate tank has a rotationally symmetric outer cross-section in the region of the surface section where the inner wall of the intermediate tank is rotationally symmetric. In this embodiment, the interior of the intermediate tank is rotationally symmetric over its entire circumference, over an axial region or over the entire length of the intermediate tank.

[0025] The vacuum toilet and the wastewater facility according to the invention can be further developed by the diameter of the outer cross-section in the rotationally symmetric region of the inner wall surface of the intermediate tank decreasing in the direction of gravity, the inlet opening preferably being arranged at the upper end of the rotationally symmetric inner wall surface of the intermediate tank, viewed in the direction of gravity. It is preferred, as a basic principle, that at the rotationally symmetric section of the intermediate tank tapers in its cross-sectional area in a direction from the inlet to the outlet opening, and preferably that the entire intermediate tank tapers in its cross-sectional area from the inlet opening to the outlet opening. Such an intermediate tank design makes up for the decrease in flow velocity caused by frictional losses of the wastewater at the external wall, by providing a reduction in the radius with which the wastewater circulates about the axis of the intermediate tank, thus preventing the wastewater from detaching itself from the intermediate tank wall. At the same time, a water column acting on the closure flap is effectively created due to tapering of the intermediate tank in the direction of the outlet opening, thus causing the closure flap to open under the force of gravity in a reliable manner of operation, without large residual amounts of wastewater remaining inside the intermediate tank when the closure flap closes again after the wastewater has passed through into the wastewater tank. The outlet channel may be formed with a constant diameter along its length, or with a varying diameter. More particularly, the outlet channel can also taper conically in the direction of the closure flap, or have a cross-sectional enlargement in the direction of the closure flap, in order to prevent any clogging in the region of the closure flap.

[0026] It is further preferred that the vacuum toilet or the wastewater facility according to the invention be developed such that the entire intermediate tank is rotationally symmetric. A rotationally symmetric shape should be understood in this case, as already described in the foregoing, as one where the inner cross-sectional area of the interior of the intermediate tank is rotationally symmetric about a longitudinal axis of the intermediate tank, whereas the outer surface of the intermediate tank can be freely designed in that respect and may have rotational symmetry or a shape that is not rotationally symmetric. A rotationally symmetric design may be a shape of circular cross-section, but according to the invention may also include shapes that depart from the circular and are in the shape of oval or elliptical cross-sectional areas.

[0027] Finally, according to another preferred embodiment of the vacuum toilet or the wastewater facility according to the invention, the vacuum generator is arranged in the interior of the intermediate tank by means of an ejector orifice and said ejector orifice is connected to the region of the intermediate tank axis and preferably coaxially with the intermediate tank axis. This embodiment provides an advantageous arrangement of the ejector orifice in a region which is typically not exposed to wastewater, due to the shape in which the wastewater moves inside the intermediate tank, so that the risk of wastewater entering the vacuum generator can be significantly reduced or entirely avoided. The ejector orifice may be radial in orientation, for example, and an axial orientation or a radial-axial orientation can also be provided. Inside the intermediate tank, more specifically, the entire vacuum generator may be arranged in the region of the axis, for example in the form of a Venturi-type ejector connected to a source of compressed air for generating the vacuum. This allows the intermediate tank with the vacuum generator to be of compact design. Depending on the specific installation situation and access to systems already existing inside the vehicle, other configurations are also basically possible, for example connecting a vacuum port that opens into the intermediate tank to a central vacuum system, or a vacuum generator that is a central component of the vacuum toilet.

[0028] It is still further preferred that the rotationally symmetric wall section is formed at an insert member and the intermediate tank has an external wall which surrounds said insert member. In this configuration, the intermediate tank is double-walled in sections thereof. The wastewater feed line opens into the insert member, in which vacuum extraction is also carried out in an advantageous manner. In this way, it is possible for the underpressure for sucking out the wastewater to be created and maintained better.

[0029] Another aspect of the invention is a method for controlling a vacuum toilet, comprising the steps of: generating an underpressure in the interior of an intermediate tank by means of a vacuum generator, opening an outlet valve in a wastewater feed line which connects a toilet bowl to the interior of the intermediate tank, feeding an amount of wastewater out of the toilet bowl via the wastewater feed line into the interior of the intermediate tank, the interior of the intermediate tank being enclosed by an inner wall surface which is arranged rotationally symmetrically about an axis, and the wastewater being fed into the interior of the intermediate tank with a tangential directional component and preferably in the tangential direction in relation to said axis.

[0030] The method can be developed by the wastewater from the interior of the intermediate tank flowing in front of an outlet opening and accumulating in front of said outlet opening, and the outlet opening being sealed by a closure element which is moved from a closed position into an open position when the weight force of the wastewater exceeds a predetermined value.

[0031] The method can be developed by the closure element being a pivotably mounted flap which is moved into the closed position by a counterweight.

[0032] The method described in the foregoing can be carried out using the vacuum toilet according to the invention. The preferred embodiments of the vacuum toilet and its manner of operation, as previously described, therefore provide further development of the method according to the invention.

[0033] Preferred embodiments of the invention shall now be described in greater detail with reference to the attached Figures, in which:

[0034] FIG. 1: shows a schematic side view of a first preferred embodiment,

[0035] FIG. 2: shows a schematic top view of a part of the embodiment according to FIG. 1 in a cutaway view along line A-A in FIG. 1,

[0036] FIG. 3: shows a schematic side view of a second preferred embodiment; and

[0037] FIG. 4: shows a schematic top view of a part of the embodiment according to FIG. 3 in a cutaway view along line A-A in FIG. 3.

[0038] The vacuum toilet shown in FIG. 1 comprises a toilet bowl 10 with a bowl outlet opening 11 which opens into a wastewater feed line 12. In wastewater feed line 12, a pneumatically operated shut-off valve 20 which can block or release flow through wastewater feed line 12 is arranged adjacent to bowl outlet opening 11.

[0039] Wastewater feed line 12 opens into an intermediate tank 30. Intermediate tank 30 has a funnel shape and is formed in a rotationally symmetrical manner about an axis 31. When installed as shown, intermediate tank 30 is arranged such axis 31 is vertically oriented, that is to say it extends in the direction of gravity.

[0040] Intermediate tank 30 has an interior 32 which is laterally defined by a conical intermediate tank wall 33. At its top end, intermediate tank 30 is closed by a circular lid 34.

[0041] Intermediate tank 30 is subdivided in an upper section 30a and a lower section 30b. The upper section has a shape which tapers conically downwards in the direction of vertical axis 31. The lower section, which is joined flush with the upper section, is in the shape of a cylindrical channel.

[0042] At the bottom end of lower section 30b, a closure flap 60 is arranged which closes an outlet opening 35 at the bottom end of the intermediate tank. In the closed position, closure flap 60 is slantingly oriented in relation to the direction of gravity, and in the embodiment shown, the closure flap extends in the closed position at an angle of 45.degree. to the direction of gravity. Closure flap 60 is mounted pivotably about a closure flap axis 61 and is pressed by means of a counterweight 62 into the closed position against the wall sections of intermediate tank 30 that defined the outlet opening.

[0043] Most of the lower section 30b of the intermediate tank, as well as closure flap 60 with its pivot axis 61 and counterweight 62, are arranged inside a wastewater tank 50, into which the wastewater is emptied from intermediate tank 30.

[0044] A central opening into which a vacuum generator 40 is sealingly inserted is provided in upper lid 34 of intermediate tank 30. Vacuum generator 40 is embodied as an ejector with a compressed air connection 41 and generates a vacuum by applying the Venturi effect to produce an underpressure and to suck air through an ejector orifice 42 arranged at the bottom end of ejector 40 and coaxial with the longitudinal axis 31 of intermediate tank 30.

[0045] Wastewater feed line 12 opens into intermediate tank 30 in the upper region of the intermediate tank at approximately the height of orifice 42 of ejector 40. As can be seen from the cross-sectional top view shown in FIG. 2, wastewater feed line 12 initially extends radially in relation to longitudinal axis 31 and then opens into a channel section 36 which extends in a direction tangential to longitudinal axis 31. Channel section 36 opens into an opening 37 which is flush with funnel-shaped wall 33 and allows the wastewater to flow in a tangential direction into the interior 32 of the intermediate tank. The wastewater therefore runs in an increasingly tight spiral starting from inlet opening 37 and downwards along the inner wall of the intermediate tank as shown by the broken line in FIG. 1 and by arrows in FIG. 2. The wastewater does not come into contact with ejector 40 or ejector orifice 42, therefore, but runs along a defined path in the direction of lower section 30b of intermediate tank 30. The wastewater collects in this lower section 30b.

[0046] As soon as the interior 32 of the intermediate tank is vented via ejector 40 or by some other vent opening, therefore causing the underpressure in the intermediate tank 30 to decrease and to approach the ambient pressure, closure flap 60 is no longer held in the closed position by the underpressure in interior 32 of the intermediate tank, and the weight force of the wastewater that has collected around the bottom section 30b of the intermediate tank presses closure flap 60 into the open position. The wastewater can therefore flow, under the force of gravity and under the atmospheric pressure in the intermediate tank and the wastewater tank, into wastewater tank 50. As soon as the wastewater has flowed out of the intermediate tank, closure flap 60 is pivoted back into the closed position by counterweight 62 and seals outlet opening 35.

[0047] A flushing operation according to the inventive vacuum toilet and wastewater facility is thus carried out in the following way. The wastewater firstly collects in toilet bowl 11, in front of the closed shut-off valve 20. When a flushing operation is initiated, flushing fluid is preferably sprayed into the toilet bowl, first of all. At the same time, an underpressure which pulls closure flap 60 into secure closure on outlet opening 35 is then created in intermediate tank 30 by means of ejector 40. After shut-off valve 20 has been opened, the wastewater is sucked into the interior 32 of the intermediate tank by the underpressure in intermediate tank 30, then runs in a spiral along tank wall 33 and collects in the lower section 30b of the intermediate tank. Shut-off valve 20 can then close again on a time-controlled basis or after the wastewater has passed through. However, shut-off valve 20 can also be kept open for longer, so that it causes the interior 32 of the intermediate tank to be ventilated via bowl outlet opening 11 after the wastewater has passed through. If shut-off valve 20 is closed, this ventilation can also be carried out, alternatively, via some other ventilation opening or via ejector 40. Ejector 40 is time-controlled, or is switched off once a particular underpressure has been reached in the interior of the intermediate tank, and subsequently does not create any further underpressure in the interior 32 of the intermediate tank. As soon as the interior 32 of the intermediate tank has been ventilated, the wastewater that has collected in the interior 32 of the intermediate tank pushes closure flap 60 open and flows into wastewater tank 50. After the wastewater has passed through, closure flap 60 is pressed by counterweight 62 back into the closed position. The vacuum toilet is then ready for the next flushing operation.

[0048] FIGS. 3 and 4 show a side view and a top view of the intermediate tank in a second embodiment of the invention. In this embodiment, an intermediate tank 130 is connected to a wastewater feed line 112. The intermediate tank is delimited from the surroundings by an outer housing wall 138. The shape of the outer housing wall can be designed substantially freely with regard to its inner surface and its external surface, since they are not a main factor affecting the flow and discharge conditions in the interior of the intermediate tank.

[0049] A conical feed funnel 133 is arranged in the interior of the intermediate tank and extends along a vertical longitudinal axis 100 and tapers conically from top to bottom. Wastewater feed line 112 opens into the conical feed funnel in a tangential direction relative to longitudinal axis 100.

[0050] An ejector 140 is arranged inside conical feed funnel 133. The ejector is concentric with longitudinal axis 100 and extends along said longitudinal axis 100. An axially oriented ejector orifice 141, through which air is sucked out of the interior of the intake funnel, is arranged at the bottom end of the ejector. A bottom outlet opening 134 of the intake funnel opens into the intermediate tank section that is enclosed by outer housing wall 138.

[0051] Wastewater flowing through the wastewater feed line into the intermediate tank according to the second embodiment is introduced tangentially into the conical intake funnel and flows inside the interior 132 of the intake funnel along the inner wall of the intake funnel and downwards along a spiral flow path to the outlet opening 134 of the funnel. The wastewater passes through the outlet opening of the funnel and collects in interior section 132a of the intermediate tank before an outlet opening 135 at the bottom end of the intermediate tank.

[0052] Like outlet opening 35 of the first embodiment, outlet opening 135 can be closed by a gravity-actuated valve and be opened by the weight force of the wastewater that collects in the intermediate tank. In the embodiment shown above, outlet opening 135 is closed by a pneumatically operated hose valve 160. When a positive air pressure is applied to hose valve 160 through a pneumatic line 161, the valve closes, and if no such overpressure is applied, hose valve 160 opens.

[0053] Improved extraction is achieved with the second embodiment, due to the arrangement of the ejector inside an enclosed region in the intermediate tank. At the same time, the advantages deriving from the wastewater being discharged with spiral motion inside the intermediate tank due to its tangential in-flow are retained, and contamination of the ejector is avoided as a result of guiding the wastewater flow in this manner.

Claims

1. A vacuum toilet, comprising: a toilet bowl with a bowl outlet opening, an intermediate tank with an inner wall surface enclosing an interior of the intermediate tank, an inlet opening formed on the intermediate tank, an outlet opening formed on the intermediate tank for connecting the interior of the intermediate tank to a wastewater container, a vacuum generator in fluidic communication with the interior of the intermediate tank for generating underpressure in said interior of the intermediate tank a wastewater feed line which connects the bowl outlet opening to inlet opening, a wastewater tank which is in fluidic communication with the interior of the intermediate tank via the outlet opening, characterised in that the inner wall surface of the intermediate tank, in at least one surface section, is formed in a rotationally symmetrical manner about an axis, and the inlet opening is arranged in said at least one surface section and has an orientation which defines an in-flow direction having a directional component tangential to said axis.

2. The vacuum toilet according to claim 1, characterised in that the wastewater feed line opens into an inlet passage arranged upstream and/or downstream from the inlet opening in the direction of flow and which defines a direction of flow into the interior of the intermediate tank, said direction defining a directional component tangential to the axis.

3. The vacuum toilet according to claim 1, characterised by a controllable closure valve in the wastewater feed line.

4. A wastewater facility for a vacuum toilet, comprising: an intermediate tank with a wall enclosing an interior of the intermediate tank, an inlet opening formed on the intermediate tank, for connecting the interior of the intermediate tank to a wastewater feed line an inlet opening formed on the intermediate tank, for connecting the interior of the intermediate tank to a wastewater tank, a vacuum generator in fluidic communication with the interior of the intermediate tank for generating underpressure in said interior of the intermediate tank characterised in that the inner wall surface of the intermediate tank, in at least one surface section, is formed in a rotationally symmetrical manner about an axis, and the inlet opening is arranged in said at least one surface section and has an orientation which defines an in-flow direction having a directional component tangential to said axis.

5. The wastewater facility according to claim 4, characterised by an inlet passage arranged upstream and/or downstream from the inlet opening in the direction of flow and which defines a direction of flow into the interior of the intermediate tank, said direction defining a directional component tangential to the axis.

6. The vacuum toilet according to claim 2, characterised in that the inlet passage defines a tangential flow direction defined, in particular in that the inlet passage runs in a tangential direction.

7. The vacuum toilet according to claim 1, characterised in that, when the intermediate tank is installed, the axis extends in a direction with a vertical directional component, and is preferably vertical in orientation.

8. The vacuum toilet according to claim 1, characterised in that the inlet opening defines a tangential flow direction, in particular that the inlet opening has a cross-sectional area whose surface normal is tangential to the axis.

9. The vacuum toilet according to claim 1, characterised in that the outlet opening has a gravity-actuated closure flap which is moved under the influence of gravity into a closed position, held in said closed position by underpressure when an underpressure in applied to the intermediate tank, and is moved into the open position by the weight force of the wastewater when wastewater lies on a surface of the closure flap facing towards the interior of the intermediate tank.

10. The vacuum toilet according to claim 9, characterised in that the gravity-actuated closure flap is mounted pivotably about a closure flap axis and has a sealing surface and a weight which presses said sealing surface under the influence of gravity against a sealing face arranged around the outlet opening, or in that the closure flap operated by spring force is pivotably mounted about a closure flap axis and has a sealing surface and a spring element which presses said sealing surface under the force of a spring against sealing surface arranged around the outlet opening.

11. The vacuum toilet according to claim 9, characterised in that the closure flap is arranged downstream in the direction of flow from an outlet channel having a cross-sectional area which is smaller than the cross-sectional area of the intermediate tank in the region of the inlet opening.

12. The vacuum toilet according to claim 9, characterised in that the closure flap has a surface which faces in the closed position towards the interior of the intermediate tank and has a surface normal with a vertical directional component and which is preferably vertical.

13. The vacuum toilet according to claim 1, characterised in that the interior of the intermediate tank has a rotationally symmetric outer cross-section in the region of the surface section where the inner wall of the intermediate tank is rotationally symmetric.

14. The vacuum toilet according to claim 13, characterised in that the diameter of the outer cross-section in the rotationally symmetric region of the inner wall surface of the intermediate tank decreases in the direction of gravity, the inlet opening preferably being arranged at the upper end of the rotationally symmetric inner wall surface of the intermediate tank, viewed in the direction of gravity.

15. The vacuum toilet according to claim 1, characterised in that the entire intermediate tank is rotationally symmetric.

16. The vacuum toilet according to claim 1, characterised in that the vacuum generator is connected to the interior of the intermediate tank by means of an ejector orifice and said ejector orifice is arranged in the region of the intermediate tank axis and preferably coaxially with the intermediate tank axis.

17. The vacuum toilet according to claim 1, characterised in that the rotationally symmetric wall section is formed at an insert member and the intermediate tank has an external wall which surrounds said insert member.

18. A method for controlling a vacuum toilet, comprising the steps of: generating an underpressure in the interior of an intermediate tank by means of a vacuum generator, opening an outlet valve in a wastewater feed line which connects a toilet bowl to the interior of the intermediate tank, feeding an amount of wastewater out of the toilet bowl via the wastewater feed line into the interior of the intermediate tank, characterised in that the interior of the intermediate tank is enclosed by an inner wall surface which is arranged rotationally symmetrically about an axis, and the wastewater is fed into the interior of the intermediate tank with a tangential directional component and preferably in the tangential direction in relation to said axis.

19. The method according to claim 18, characterised in that the wastewater from the interior of the intermediate tank flows in front of an outlet opening and accumulates in front of said outlet opening, and that the outlet opening is sealed by a closure element which is moved from a closed position into an open position when the weight force of the wastewater exceeds a predetermined value.

20. The method according to claim 19, characterised in that the closure element is a pivotably mounted flap which is moved into the closed position by a counterweight.