Abstract:
A sedimentation separator for separating solid fractions from a mixture consisting of air, liquid and solids fractions comprises a sedimenting vessel to which an air-separating unit is connected upstream. In an intermediate vessel arranged between the air-separating unit and sedimenting vessel there is arranged a float which closes off an air duct when the level of sediment in the sedimenting vessel has reached a predetermined height. Liquid purified by sedimentation is suctioned off from the upper end of the sedimenting vessel by means of a jet pump.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of International Patent Application No. PCT/EP2011/003433 filed on Jul. 9, 2011 which claims priority to German utility patent no. 20 2010 010 802.0 filed Jul. 29, 2010. The full disclosure of both applications are incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a separator for removing solid fractions from a mixture of air, liquid and solids. 
         [0004]    2. Description of Related Art 
         [0005]    Three-phase mixtures of air, liquid and solids are produced during machining of objects. These mixtures cannot be disposed of directly in the public drainage system for environmental reasons. An example of such mixtures is a mixture of air, body fluids and amalgam particles which accumulates when drilling out amalgam fillings at a dental workplace. The amalgam must not be disposed of in the public wastewater system, but must instead be collected separately and supplied for correct disposal. 
         [0006]    Various processes are used to separate the solid particles. Centrifugation of the solids has proven particularly effective for separating small particles. However, the corresponding centrifuges are expensive and, in the case of waste waters which contain amalgam particles, the legislative bodies of some countries only regard it as sufficient when these particles are separated from the liquid by sedimentation. 
         [0007]    Accordingly, these use amalgam separators which operate according to the sedimentation principle. 
         [0008]    These known sedimentation tanks generally have an outlet which is in communication with the actual sedimentation chamber by way of an overflow. 
         [0009]    The sedimentation units generally comprise a collection tank which contains the sedimented amalgam, and this collection tank has to be exchanged at intervals for an empty tank. 
         [0010]    The effectiveness of the sedimentation for an air-containing mixture is impaired by bubbles and/or foam, particularly when the liquid contains foam-forming substances such as protein or saponines or cleaning agents. 
       SUMMARY OF THE INVENTION 
       [0011]    An object of the present invention, therefore, is to provide a solids separator which operates according to the sedimentation principle and which also separates solids effectively in mixtures containing air or another gas. 
         [0012]    This object may be achieved by a separator for removing solid particles from a mixture of air, liquid and solid particles, comprising
       a sedimentation unit which has a mixture inlet and a liquid outlet and a collection tank for retained solid fractions, and   an air-separating unit having an air outlet and a mixture outlet, wherein the mixture outlet is connected to the mixture inlet of the sedimentation unit.       
 
         [0015]    In the separator according to the invention, air fractions of the mixture do not reach the sedimentation chamber. Therefore the merely two-phase mixture of liquid and solid fractions in the sedimentation chamber can separate effectively under gravity. 
         [0016]    Also, the sedimentation process is not adversely affected by an air flow passing through the sedimentation chamber. 
         [0017]    Advantageous further developments of the invention are described in further embodiments. 
         [0018]    In a sedimentation unit in which the liquid with a reduced solid content is discharged by way of an overflow, there is a risk of liquid being spilled when the collection tank is removed. Since, in the case of a mixture collected at a dental workplace, this liquid also contains germs and possibly viruses, it is desirable to prevent liquid from being spilled when servicing or exchanging a collection tank of the sedimentation unit. 
         [0019]    This object may be achieved if the liquid outlet of the sedimentation unit is connected to a liquid pump. 
         [0020]    In the separator according to the invention, an overflow is not provided and the level of the liquid located in the sedimentation unit is always below the liquid outlet of the separator since the liquid pump provided according to the invention draws off liquid from such a point. The sedimentation unit or a collection tank forming part thereof can therefore be moved by hand and tilted or exposed to accelerations without liquid escaping into the environment. 
         [0021]    There is no need to provide a complex mechanical pump if the liquid pump is a jet pump. To withdraw cleaned liquid, a jet pump is used whereof the motive fluid is the delivered air. A jet pump of this type is mechanically simple in terms of its construction and also functions in trouble-free manner over a long operating period. 
         [0022]    In the case of suction machines which are used at dental workplaces, it is possible to distinguish between wet suction machines and dry suction machines. The term wet suction machine here refers to a suction machine which also functions reliably over a long operating period in the presence of liquid. An example of a wet suction machine of this type is a water ring pump in which a circulating water ring is part of the delivery device. In any event, pumps of this type have to be designed to withstand a liquid and/or steamy environment over a long period. A dry suction machine refers to the type usually used for delivering dry gases. Typical examples of such dry suction machines used in dentistry are piston machines and side channel machines as well as rotor machines with an axially acting rotor or radially acting rotor. 
         [0023]    It is proposed that a wet suction machine, in particular a water ring pump, be used at the mixture outlet of the liquid pump for the purpose of generating the negative pressure required at the dental workplace. 
         [0024]    Alternatively, it is proposed that the mixture of air and liquid obtained at the outlet of the liquid pump be supplied to a second air separating unit whereof the air outlet is then connected to the inlet of a suction fan, which can then be a dry suction machine. 
         [0025]    With a separator, wherein the air-separating unit has a chamber which is in communication with the sedimentation unit and in which a level sensor is arranged, this level sensor being used to control a position of a control body with respect to a valve seat of an air channel or a mixture channel in order to throttle or block the air channel or the mixture channel, the user of a suction unit comprising such a separator is made expressly aware that the capacity of the sedimentation unit has been reached or exceeded by a decrease in, or failure of, the suction power. 
         [0026]    The compulsory throttling or blocking of the suction air flow is achieved in mechanically simple manner if the level sensor comprises a float and the float is mechanically connected to the control body. 
         [0027]    If the control body is pre-tensioned in a closed position by a spring and can be locked in an open position by a releasable locking mechanism and in that the locking mechanism can be disengaged by the level sensor, it is ensured that the separator operates with a constant air throughput when the maximum fill level of the solid sediment is not yet reached and promptly reduces or completely stops the air throughput when the maximum permissible fill quantity is reached or exceeded. 
         [0028]    A level sensor comprising a sensor plate which is supported on the base of the collection tank by way of a spring can be assembled here very simply and reliably from a small number of parts. 
         [0029]    An elastomer block spring as a spring is loaded according to the weight of the sediment bed and can be constructed simply and in a manner which is suitable for contaminating environmental conditions. 
         [0030]    An elastomer block spring having a liquid-tight surface skin is advantageous here in terms of a fluidic sealing of the interior of the block spring with respect to the interior of the sedimentation chamber. 
         [0031]    If the sensor plate is pivotally supported by the collection tank, it is readily possible to derive a useful movement with a transverse component with respect to the device axis from the weight-related positional change of the sensor plate. A movement of this type is suitable for releasing a locking mechanism with which the control body is held in an open position. 
         [0032]    A separator, wherein the control body supports a rod which is guided into an interior of the collection tank and supports a locking head at its free end, gives a solution for simple locking of the control body controlling the air throughput through the separator in an open position, which is maintained until the maximum fill level in the sedimentation unit is reached. 
         [0033]    A locking mechanism comprising a counter-locking device which cooperates with the locking head of the rod for the control body is notable here for a particularly simple mechanical construction. 
         [0034]    The counter-locking device may be constructed as a wire which can be moved by a cam body supported by the sensor plate with a transverse movement component with respect to the rod axis or which can be cut by a blade moved along with the sensor plate. This is one alternative for a releasable locking mechanism for the control body. 
         [0035]    Another alternative is a counter-locking arm which is supported by the pivotally mounted sensor plate. 
         [0036]    A rod supporting the control body, wherein the rod is supported by two parallel-spaced membranes, enables the control body to be axially displaceably mounted with a low degree of friction using mechanically simple means. 
         [0037]    It is to be understood that the aspects and objects of the present invention described above may be combinable and that other advantages and aspects of the present invention will become apparent upon reading the following description of the drawing and detailed description of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    The invention is explained in more detail below with reference to exemplary embodiments with the aid of the drawings, which show: 
           [0039]      FIG. 1  which is an axial section through a sedimentation amalgam separator with a removable collection tank and liquid extraction pump; 
           [0040]      FIG. 2  which is an enlarged axial section through an axial guide for a throughput control body of the amalgam separator according to  FIG. 1 ; which axial guide is provided at the upper end of the amalgam separator; 
           [0041]      FIG. 3  which is an amalgam separator according to  FIG. 1  with a series-connected further air separator for use in a dental workplace, for which a dry suction machine is provided; 
           [0042]      FIG. 4  which is a similar view to  FIG. 1 , in which a locking device for an air-throughput control body is provided; and 
           [0043]      FIG. 5  which is a similar view to  FIG. 4 , but showing a modified locking device for the air-throughput control body. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0044]    While this invention is susceptible of embodiment in many different forms, there is shown in the drawing and will herein be described in detail one or more embodiments with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. 
         [0045]    Reference throughout this description to features, advantages, objects or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, any discussion of the features and advantages, and similar language, throughout this specification may, but does not necessarily, refer to the same embodiment. 
         [0046]    In  FIG. 1 , an amalgam separator which operates according to the sedimentation principle is denoted as a whole by  10 . 
         [0047]    This separator comprises an inlet connection piece  12 , which is acted upon from a dental workplace with a mixture of air, body fluids and solid particles (bone fragments, amalgam particles etc.). A suction cannula  13 , which is used to extract rinsing water, saliva, blood and drilling debris from the mouth of a patient, is shown schematically as a source for this mixture. 
         [0048]    The inlet connection piece  12  is aligned horizontally and leads tangentially into a circumferential wall  14  of a cyclone  16  with a vertical axis. 
         [0049]    Provided concentrically to the circumferential wall  14 , with a radial spacing to the inside, there is a conducting cavity  18  which widens conically downwards and is positioned on a cylindrical air outlet channel  20  such that the lower edges of the outlet channel  20  and conducting cavity  18  are located in a transverse plane. 
         [0050]    In the annular space formed between the conducting cavity  18  and the outer surface of the outlet channel  20  on the one hand and the inner surface of the circumferential wall  14  on the other, the mixture supplied through the inlet connection piece  12  spirals slowly downwards, whereby the liquid and solid constituents of the mixture are pressed against the inner surface of the circumferential wall  14  by centrifugal force. The lighter air fractions then move inwards and arrive in the cylindrical outlet channel  20 . 
         [0051]    By way of the outlet channel  20  and an attached angular piece  22 , a pilot angle valve  24 , a vertical connecting line  26 , a jet pump  28 , a deflection angle  30  and a further pilot angle valve  32 , the air flow is extracted by a suction machine  34  illustrated merely schematically in the drawing, from where the air is then delivered to the environmental atmosphere. 
         [0052]    In the exemplary embodiment considered here, the suction machine  34  is a wet suction machine in the form of a water ring pump. 
         [0053]    The liquid and solid fractions of the supplied mixture which are separated in the cyclone  16  arrive from the cyclone  16  in an intermediate chamber  36  with a cylindrical circumferential wall  38  and a conical base wall  40 . 
         [0054]    The lower end of the conical funnel-shaped base wall  40  is provided with a discharge connection piece  42  which leads into the interior of a cup-shaped collection tank  44  which is open at the top. This is held by a cover plate  46  which is connected to the intermediate tank  36 . 
         [0055]    The mixture of liquid and solid fractions which is discharged from the end of the discharge connection piece  42  arrives inside the collection tank  44  and there forms a liquid volume  48  and a sediment volume  50  located beneath it. 
         [0056]    The mixture of liquid and solid fractions which is supplied from the intermediate tank  36  is separated by gravity inside the collection tank  44 , so that the top liquid layer in the collection tank  44  has an effectively reduced solid content. 
         [0057]    The jet pump  28  draws from this top liquid layer. 
         [0058]    The jet pump  28  has an injector  58  (located at the top in the drawing) which is acted upon by the suction air and tapers downwards. The end of the injector  52  projects with an annular gap  54  into a collector  56  which tapers conically downwards. 
         [0059]    By way of an angled channel  58 , the annular gap  54  communicates with a suction pipe  60  which hangs down from the cover plate  46 . 
         [0060]    A slim, cup-shaped filter body  62 , which can consist of a sintered filter material, for example, is pushed over the suction pipe  60 . The filter body  62  only needs to have filter properties in the portion located below the end of the suction pipe  60 . 
         [0061]    As shown in the drawing, the lower end of the suction pipe  60  is located a distance D above the lower end of the discharge connection piece  42 . This prevents the mixture of liquid and solid fractions which is discharged from the discharge connection piece  42  from arriving directly at the suction connection piece  60 . Instead, this mixture has to remain a certain length of time inside the collection tank  44  so that there is sufficient time for the sedimentation of the solid fractions. 
         [0062]    The amalgam separator described above operates as follows: 
         [0063]    The mixture of air, liquid and solid particles enters the cyclone  16  by way of the inlet connection piece  12 . The air fractions are separated there and extracted by way of the outlet channel  20 . 
         [0064]    The liquid and solid fractions of the mixture arrive in the collection tank  44  by way of the intermediate tank  36 . The majority of the solid fractions deposit there, thereby increasing the sediment volume  50 . Clarified liquid in the top layer of the liquid volume  48  is extracted therefrom by the jet pump  28  which uses the air extracted by the suction machine  34  as a motive fluid. 
         [0065]    If the collection tank  44  needs exchanging due to the sediment volume  50  reaching a maximum permissible level, the collection tank  44  is removed from the cover plate  46 . If the tank is shaken or tilted as it is removed, this does not cause any spillage of the liquid still inside the collection tank  44  since the liquid level is at the lower end of the suction pipe  60  and this is clearly below the upper edge of the collection tank  44 . 
         [0066]    The removed collection tank  44  can then be closed by a suitable cover and sent to a waste management company. An empty collection tank is then fitted. 
         [0067]    It can be seen that the amalgam separator can therefore be reliably handled without a risk of the environment being contaminated by germ-containing liquid. 
         [0068]    To indicate clearly to the user of a suction system containing the separator that the collection tank  44  needs exchanging, a mechanism is integrated in the separator, which throttles the suction air flow, or interrupts it completely, when the maximum permissible level of the sediment volume  50  is reached. 
         [0069]    This mechanism comprises a control body  64  which comprises two tightly connected shell parts  66 ,  68 . These each have a cylindrical wall  70  and  72  located in the central plane and an end wall  74  and  76  tapering conically to the upper and lower end of the control body  64  respectively. 
         [0070]    The control body  64  is supported by a hollow rod  78  which is arranged with a large radial play in the interior of the outlet channel  20  and is mounted by way of two spaced membranes  80 ,  82  (see  FIG. 2 ) on a cylindrical attachment  84  of the cyclone  16 . 
         [0071]    The upper conical end wall  64  of the control body  64  constitutes a control surface which cooperates with the lower end of the cylindrical outlet channel  20 . 
         [0072]    At the same time, the control body  64  forms a float which is raised when liquid rises back into the interior of the intermediate tank  36 . The liquid rises back in this way when the upper delimiting surface of the sediment volume  50  reaches the lower end of the filter body  62 . This then blinds and the jet pump  28  is only able to extract liquid from the collection tank  44  in reduced measure or no longer at all. 
         [0073]    Liquid which is separated in the cyclone  16  therefore remains together with the contained solid fractions inside the collection tank  44  and rises inside the intermediate tank  36 . This causes the control body, which at the same time acts as a float, to be displaced axially upwards, which results in the passage between the lower end of the outlet channel  20  and the upper side of the end wall  74  being reduced and finally closed completely. 
         [0074]    The dentist operating at the workplace equipped with the amalgam separator is thus made aware of the fact that the collection tank  44  is full and needs exchanging as a result of the reduction in the suction power or complete loss of suction power. 
         [0075]    If the amalgam separator shown in  FIG. 1  is used in conjunction with a dry suction machine, then a further cyclone  16 ′ is connected downstream thereof according to  FIG. 3 , which cyclone  16 ′ is of a similar construction to the cyclone  16  and therefore does not need describing in detail. However, the cyclone  16 ′ does not include those components which serve to indicate the fill level of the collection tank  44  and the compulsory reduction or compulsory switching-off of the suction power. 
         [0076]    It is clear that this second cyclone  16 ′ can be realised using substantially the same parts as the cyclone  16 . 
         [0077]      FIG. 4  shows a further modified amalgam separator in which the control body  64  is held in a fully open position until the maximum permissible sediment level in the collection tank  44  is reached. 
         [0078]    The control body  64  is now additionally equipped on its outer surface with guide wings  88  which are distributed in a star shape in the circumferential direction and by way of which it moves over the inner surface of the intermediate tank  36  with little friction. 
         [0079]    The rod  78  is pre-tensioned in the closed position by a spring  90  in the attachment  84 , which acts on it by way of a spring seat  92 . The spring seat  92  is accessible from the outside by way of a removable cap  94  in order to press it downwards in opposition to the force of the spring  90 . 
         [0080]    Securely attached to the lower end of the control body  64 , there is a further rod  96 , which is provided with a radially projecting conical head  98 . In an operating position, this projects beyond the lower end of the discharge connection piece  42  and, when the spring seat  92  is pressed downwards as described above, the conical ramp face of the head  98  moves over a locking wire  100  which is tensioned transversely through the interior of the collecting tank  44 . This can be a plastic wire, the ends of which are securely welded to the circumferential wall of the collection tank  44 . 
         [0081]    Inserted in the bottom portion of the collection tank  44 , there is an elastomer block spring  102  which is made from an elastomeric porous material with a fluid-tight outer skin A sensor plate  104 , which is guided up to the circumferential wall of the collection tank  44  with a relatively large sliding play, rests on the block spring  102 . The sensor plate  104  can be made for example from a low-friction plastic material such as PE or PA. 
         [0082]    The upper side of the sensor plate  104  supports a holding plate  106 . For clearer illustration, this is shown located on the axis of the collection tank  44 . In practice, it is arranged adjacent to the end of the discharge connection piece. 
         [0083]    The upper end of the holding plate  106  supports a horizontal blade  108  which extends away from it to the left in the drawing and can be formed by a ground metal plate, similar to a razor blade. 
         [0084]    When the tank is empty, the lower edge of the blade  108  projects a predetermined distance beyond the locking wire  100 . 
         [0085]    If, during operation of the amalgam separator  10 , a sediment volume  50  forms over the sensor plate  104 , the block spring  102  is compressed increasingly by the weight of the sediment volume. The rigidity of the block spring  102  is selected so that the blade  108  arrives at the locking wire  100  precisely upon reaching the maximum permissible sediment volume  50  up to a predetermined tolerance amount, which can be for example approximately 10-15%. 
         [0086]    Upon further separation of amalgam and other solids, the blade  108  then comes into engagement with the plastic locking wire  100  and then cuts through this. The head  98  of the rod  96  is then released and, under the pre-tension of the spring  90 , the control body  64  is then moved upwards so that its end wall  74  closes the lower end of the outlet channel  20 . There is now no longer any suction power at a suction cannula  13  connected to the inlet of the amalgam separator  10 , which alerts the user to the fact that the collection tank  44  has to be exchanged for an empty one. 
         [0087]    In a modification, the blade  108  can also be mounted at the upper end of the holding plate  106  in such a way that the blade  108  drops outwards and downwards so that, when the sensor plate  104  is lowered, a relative movement takes place simultaneously between the blade  108  and the locking wire  100 . This improves the cutting action. 
         [0088]    As another alternative, it is also possible to mount a cam face at the end of the holding plate  106 , for example in the form of an outwardly and downwardly angled rod, instead of the blade  108 , so that, when the sensor plate  104  moves downwards, the locking wire  100  is then pressed to the right in  FIG. 4  without interference, causing the head  98  to likewise be released and the control body  64  to then be moved into the closed position under the pre-tension of the spring  90 . 
         [0089]    The exemplary embodiment according to  FIG. 5  corresponds substantially to that of  FIG. 4  and therefore, in this regard, does not need to be explained again in detail. 
         [0090]    However, the sensor plate  104  is now tiltably mounted at its one end (positioned on the left in the drawing) on a step  100 , which is incorporated in the circumferential region (positioned on the left in  FIG. 5 ) between the base and circumferential wall of the collection tank  44 . The end of the holding plate  106  rigidly supports a locking arm  112  which cooperates with the head  98 . 
         [0091]    If a sediment volume of sufficient mass builds up over the sensor plate  104 , the sensor plate  104  is pivoted about the edge of the step  110  in opposition to the force of the block spring  102 . If the sensor plate  104  pivots far enough, the locking arm  112  is then released from the head  98  of the rod  96 , causing the control body  64  to be moved back into the closed position under the force of the spring  90 . 
         [0092]    Large numbers of the amalgam separator described above and shown in the drawing can be realised economically from plastic injection-moulded parts. It has good operational reliability since it is not possible to continue working when a predetermined maximum permissible final sediment volume is reached in the collection tank. 
         [0093]    With this, it is also ensured that, when the collection tank is removed, no liquid spills from the tank if this is tilted, for example, or removed in jolting manner. 
         [0094]    The amalgam separator can be used directly on wet suction machines and can also be used on dry suction machines when a further air separator, which can be composed of substantially the same components as those of the amalgam separator, is connected to it in series. 
         [0095]    It is to be understood that additional embodiments of the present invention described herein may be contemplated by one of ordinary skill in the art and that the scope of the present invention is not limited to the embodiments disclosed. While specific embodiments of the present invention have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims.