Patent Description:
Dental treatment units are complex machines that have been industrially produced since the beginning of the <NUM>th century. Dental treatments units comprise different portions described later in the detailed description of <FIG>.

It is worth underlining that dental treatment units are durable equipment, intended for a service life lasting about <NUM>-<NUM> year, which can reach up to <NUM> years and beyond. It is apparent that in this long period of time, dental treatment units will undergo a series of planned maintenance interventions by a maintenance technician, and probably even repair interventions following failures.

Typically, said dental treatment units are used to perform dental therapies on a patient laying or seating on dental chair. During therapies, typically dentists use dental instruments supported by a dentist's board, instruments often provided with an air/water spray. Moreover, the patient undergoing therapy continually secretes saliva and can bleed during therapy. Finally, during therapies debris is generated due to the use of dental instruments, e.g. small pieces of enamel, dentin, old amalgam or aesthetical material fillings. In order to keep the operative field clean, in the art it is known to perform said therapies while a suction system is active, which removes water, saliva, blood and solid debris (enamel, dentin, amalgam, polymeric materials) from the oral cavity of the patient. Said suction is performed placing in the oral cavity of the patient a disposable or sterilisable suction cannula, which is mounted on a tube holder terminal at the end of a suction tube, in its turn connected to the water unit.

Typically, suction tubes are corrugated tubes, with the aim of conferring the robustness needed in order to prevent their collapsing under the action of suction.

In the art, it is customary to provide a suction system placed downstream said dental treatment unit. In the case of dental practices provided with a plurality of dental treatment units, a suction system is often connected to a plurality of dental treatment units. Said suction system generates vacuum, which in turn generates a suction flow that removes saliva, blood and detritus from patient's oral cavity. There are known suction systems of different kinds: dry line suction systems, wet line suction, etc..

In the case of dry line suction systems, said suction flow containing materials coming from the patient's oral cavity passes through a canister allowing to separate air from the liquid and solid content of the suction flow. Typically, the liquid is drained in the drain of the dental treatment unit, while solids are retained by said canister, which must be emptied and cleaned periodically.

In the case of wet line suction systems, said suction flow containing materials coming from the patient's oral cavity is drained directly in the suction system of the dental treatment unit.

There are provided two cases wherein a suction valve according the present invention is needed:.

In the lower end dental treatment units, each treatment unit is provided with a suction valve allowing the connection of the different dental treatment units placed in a dental practice comprising at least two dental treatment units, each valve according to the present invention being provided on the tubing leading to the suction system placed downstream the dental treatment units.

In order to prevent noise and pressure drop by the suction cannula not inserted in the patient's oral cavity (the non-used cannula remains in its seat on the dental assistant's table), there are typically two possibilities:.

In the case of dental practices provided with a plurality of dental treatment units connected to the same suction systems, a single (upper range) dental treatment unit might be provided with three valves according to the present invention: one valve for each of the two cannulas, and a third valve placed on the tubing leading to the suction systems.

Said suction valves are well known in the art, and have been industrially produced for many years. The documents quoted hereunder represent the known art for said suction valves. It is worth noting that the numbers quoted in the known art documents are the numbers indicated in the single document.

<CIT>, describes a suction valve wherein there is provided a conduit <NUM>, <NUM>, <NUM>, <NUM> allowing the connection of the suction conduit <NUM> to the chamber above a diaphragm <NUM> through a pilot valve <NUM>. Said suction conduit is not provided with a non-return valve.

<CIT>, describes a suction valve, provided with a conduit 30a connecting the suction conduit to the chamber above a diaphragm <NUM>, through a selection valve <NUM>. This valve, too, is not provided with a non-return valve.

<CIT>, describes a solenoid valve provided with a suction conduit 8a connecting the top chamber to a diaphragm <NUM> through a selection valve <NUM>. The spring which normally actuates the diaphragm is eliminated. This valve, too, is not provided with a non-return valve.

<CIT>, discloses a suction valve provided with a connection tubing <NUM> placed between suction conduit and chamber above the diaphragm through a valve <NUM>. This valve, too, is not provided with a non-return valve.

<CIT>, describes a suction valve provided with a shutting-off mechanism associated on the one hand with the suction channel and on the other hand with a supply channel that feeds a supplementary medium to the suction channel. Each of the two channels can be open or closed at the same time or alternatively. With the contemporary aperture or closure the supplementary medium can be provided to the suction channel during the working of suction. Said suction valve is provided with a suction conduit <NUM>, <NUM>, <NUM> connecting the suction channel to the chamber <NUM> above a diaphragm <NUM>. This suction valve, too, is not provided with a non-return valve.

<CIT>, describes a suction valve provided with a suction conduit <NUM> connecting the suction conduit <NUM> to the chamber <NUM> above the diaphragm <NUM> through a selection valve <NUM>. This suction valve, too, is not provided with a non-return valve.

<CIT>, discloses a suction valve provided with a conduit <NUM> connecting the suction conduit <NUM> to the above chamber <NUM> through a selection valve <NUM>. <CIT> shows a similar suction valve. Those suction valves, too, are not provided with a non-return valve <CIT> and <CIT> both show the preamble of independent claim <NUM>.

It is worth noting that the companies (Duerr Dental, Siemens AG, Cattani S. , Metasys) owning the patents quoted as known art represent the most reputed manufacturers of dental medical devices. The problems of noise, pressure drop in the suction system, and of the service life of suction valves have been known in the art for many years and have not found a satisfying solution yet.

Document <CIT> discloses a self-piloting damping vacuum diaphragm valve with a check valve in the conduit connected to the piloting valve.

Aim of the present invention is providing an improved suction valve, having a service life longer than that of the valves on the market, including the suction valve presently produced by the applicant. In particular, one of the aims of the invention is preventing failures in the suction valve, so preventing emergency interventions causing downtimes to dental treatment units.

This object is achieved by an apparatus having the features of the independent claim.

Advantageous embodiment and refinements are specified in the claims dependent thereon.

According to the present invention, the suction valve is provided with the same main portions as the known art valves. The suction valve according to the present invention comprises an input conduit, an output conduit, and a connecting conduit provided with a diameter smaller than the previous two. Said connecting conduit leads from the output conduit to a chamber placed above a diaphragm arranged transversally to said input conduit and output conduit. The diaphragm keeps the valve in a normally closed position.

The invention relates to a valve wherein between the output conduit and the input conduit there is provided a valve seat. Said valve seat cooperates with the diaphragm, so that when said diaphragm is pushed against said valve seat, the passage between said two output and input conduit is interrupted, while when the diaphragm is uplifted from the valve seat, the passage between output conduit and input conduit is open.

The present invention provides two conduits, an output conduit and an input conduit, which are oriented with their longitudinal axes according to incident directions, in particular according to two perpendicular directions. Said conduits in the crossing zone form a contact edge along the internal part of the angle surrounded by them, which has an arcuate saddle shape. Said contact edge constitutes the valve seat, with which the facing side of a flexible diaphragm cooperates. The flexible diaphragm is arranged in a secant way with respect to both longitudinal axes of the input and output conduit, respectively, and with respect to the external side of the angle zone filleting the conduits. Said diaphragm is elastically deformable against said contact edge, so as to close the passage between the output conduit and the input conduit, through a pressure on the side of the diaphragm, opposed to the contact one with said contact edge, while said diaphragm takes a position distanced from said contact edge when it is not pushed against the edge.

According to the present invention, in the suction valve said input conduit and output conduit are preferably perpendicular. Said connecting conduit is provided with en entry point that protrudes in the output conduit, and at the entry point of said connecting conduit there is provided a non-return valve. Such non-return valve allows the emptying of the suction valve in the opening step of the valve, preventing the upwelling of dirt/liquids.

In a preferred embodiment, the connecting conduit is provided for the main part of its length outside the body of said valve.

In a preferred embodiment, said non-return valve is an umbrella valve.

In a preferred embodiment, the non-return umbrella valve is preloaded.

In an alternative embodiment, said non-return valve is provided in the form of duck bill valve, or a ball valve.

In a preferred embodiment, the entry point of the connection conduit inside the suction valve is placed perpendicularly to the airflow.

The advantages of the present invention are manifold.

The first advantage is preventing the upwelling of water and dirt inside the valve, so prolonging the service life of the valve itself.

A second advantage is that the connecting conduit placed outside the body of the valve makes its industrial production easier.

A third advantage is that the particular position of the entry point of the connecting point reduces the possibility of liquid upwelling.

A fourth advantage is that it was experimentally verified that with the valves according to the known art, the position of installation of the valve affects the duration of the service life of the valve, with a marked worsening (shorter service life) when said valve is installed tilted up to <NUM>°. With the valve according to the present invention, any degree of tilting affects neither the working of the valve nor the duration of its service life.

Further advantages and properties of the present invention are disclosed in the following description, in which exemplary embodiments of the present invention are explained in detail based on the drawings:.

<FIG> shows a dental treatment unit <NUM> according to the known art, comprising a patient chair <NUM> for a (not shown) patient and a water unit <NUM>. The water unit <NUM> typically supports a bowl <NUM>; a dentist's board <NUM> provided with a dentist's control console <NUM> for inputting commands, and a plurality of dental instruments <NUM> supplying water (air/water syringe, micromotor, turbine, calculus scaler, etc.); an assistant's board <NUM>; an operating lamp <NUM>. The water unit <NUM> is also provided with a water-to-cup spout <NUM> for supplying water to a (not shown) glass. The dental treatment unit <NUM> is provided with a foot control <NUM> and can optionally comprise a screen <NUM> and an intraoral X-ray unit <NUM>.

On the assistant's table <NUM> there are provided at least two suction cannulas <NUM>, to be inserted into patient's oral cavity, mounted on respective suction tube terminals <NUM> applied to the distal end of respective suction tubes <NUM>. Traditionally the cannulas are of two different measures, one having a larger diameter, and the other having a smaller diameter. Said cannulas <NUM> are connected through said suction tubes <NUM> to said water unit <NUM>. It is known in the art that the seat of said cannula terminals <NUM> on the assistant table <NUM> comprises a micro switch, allowing to electrically actuate the valves of the suction system placed downstream.

The suction valve according to the present invention is a traditional component of dental treatment units, and is typically placed at the proximal end of suction tubes <NUM>, in a position not visible in <FIG>. Alternatively or in addition, said suction valve is interposed along the tubing connecting the dental treatment unit to the downstream suction system, in a position not visible in <FIG>. In all cases, the suction system is placed downstream the dental treatment unit, often in a special engine room.

<FIG> shows a suction valve according to the known art, in particular according to <CIT>, wherein the output conduit <NUM> connected to the downstream suction system is intercepted by a connecting conduit 30a leading to the chamber <NUM> above a diaphragm <NUM> through a selection valve <NUM>.

In the normal working conditions of the suction system, the suction valve is open, and therefore the diaphragm <NUM> is uplifted, which allows the passage of the suctioned flow in the conduits <NUM> and <NUM>. This causes an upwelling of liquid and dirt in the conduit 30a which jeopardizes the working of the solenoid valve <NUM>.

<FIG> show the suction valve <NUM> according to the present invention in an axonometric and in a side view, respectively. Said valve <NUM> is produced in a plastic material, preferably polybutylene terephthalate (PBT), which is a material resistant to chemical aggression.

Said Figures show the suction valve <NUM> according to the present invention, comprising an input conduit <NUM>, an output conduit <NUM>, and a connecting conduit <NUM> provided with a diameter smaller than the previous two. Said connecting conduit <NUM> is provided with en entry point <NUM> (<FIG>) that protrudes in the output conduit <NUM>. Said input conduit <NUM> and output conduit <NUM> are preferably perpendicular. Said connecting conduit <NUM> leads from the output conduit <NUM> to a chamber <NUM> placed above a diaphragm <NUM> which keeps the valve <NUM> in a normally closed position (see <FIG>). In <FIG>, said connecting conduit <NUM> is visible in part as a dashed conduit.

<FIG> shows the suction valve <NUM> according to the present invention in a longitudinal section, which allows to compare it with the known art valve shown in <FIG>. Comparing <FIG> (known art) and <FIG> is easy to observe that said two valves share the main components. The input conduit <NUM> of <FIG> corresponds to the input conduit <NUM> according to the present invention; the diaphragm <NUM> of <FIG> corresponds to the diaphragm <NUM> of the present invention, while the output conduit <NUM> of <FIG> corresponds to the output conduit <NUM> of the present invention. The connecting conduit 30a of <FIG> corresponds to the connecting conduit <NUM> of the present invention. The selection solenoid valve <NUM> of <FIG> corresponds to the pilot valve <NUM> of the present invention.

<FIG> shows the suction valve <NUM> in its resting condition, i.e. when the suction system is inactive. <FIG> shows that the suction valve <NUM> is a normally closed valve, i.e. at atmospheric pressure the conformation of the diaphragm <NUM> is such to close both conduits <NUM> and <NUM>. In particular, said diaphragm <NUM> is placed transversally to both said conduits <NUM> and <NUM>.

The conduit <NUM> is connected upstream to the suction cannula <NUM> through a corrugated tubing <NUM>, or alternatively to the (not shown) tubing connecting a dental treatment unit <NUM> to a (not shown) suction system, placed downstream said dental treatment unit. The rubber diaphragm <NUM>, due to its conformation, blocks said two conduits <NUM>, <NUM>, preventing them from communicating. In the suction valve <NUM> there is provided a top chamber <NUM>, which is delimited at its bottom by said rubber diaphragm, while the other walls are formed by the body of the suction valve <NUM>.

Said suction valve <NUM> further comprises:.

When said pilot valve <NUM> is not electrically supplied (resting position), the conduit <NUM> connects the external environment with the top chamber <NUM>. When the pilot valve <NUM> is electrically supplied, the closing of the conduit <NUM> in the point <NUM> blocks the passage of environmental air, while the opening of the conduit <NUM> connects the top chamber <NUM> with the output conduit <NUM> through the connecting conduit <NUM>.

It is worth noting that, thanks to the micro switch on the assistant's table <NUM>, the extraction of a suction cannula <NUM>, in particular of the cannula terminal <NUM>, from its seat in the assistant's table <NUM> triggers the electrical impulse for the opening switching of the pilot valve <NUM>. On the other end, the positioning of the cannula terminal <NUM> back to its seat in the assistant's table <NUM> closes the pilot valve <NUM>.

<FIG> show, like frames of a movie, what happens inside the suction valve <NUM> when the (not shown) suction system is activated, connected downstream the suction valve <NUM>.

It is worth noting that the activation of the suction valve <NUM> occurs through successive steps:.

<FIG> shows the working condition that occurs when the suction system is activated, and therefore air, indicated by the bigger white arrows, arrives to the suction valve <NUM>, coming from the environment and being sucked through the output conduit <NUM> connected to the suction system. The smaller white arrows show the action of air on the diaphragm <NUM>.

With the activation of the suction system, the output conduit <NUM> undergoes depression, which further draws the diaphragm downward, ensuring/improving the seal of the input conduit <NUM>. In such condition, the pilot valve <NUM>, not electrically supplied, connects the camera <NUM> with the atmosphere through the conduit <NUM>. The conduit <NUM> is closed in the point <NUM>.

<FIG> shows the working condition that occurs in the following moment, when the pilot valve <NUM> is opened through an electrical impulse coming from the micro switch (switching step of the opened valve) caused by the extraction of the cannula terminal <NUM> from its seat on the assistant's table <NUM>. The pilot valve <NUM> closes the conduit <NUM> in the closing point <NUM>, connecting the output conduit <NUM> with the chamber <NUM> above the diaphragm <NUM>. In the chamber <NUM> there is provided a condition of a pressure lower than the pressure in the input conduit <NUM> (atmospheric pressure) and this allows the upward flexing of the diaphragm, connecting the output conduit <NUM> with the input conduit <NUM>. The small white arrows show the overall path of the airflow. In this condition, the suction flow is activated.

The small white arrows of the camera show the direction of movement of air, and the direction of uplifting of the diaphragm. The air substantially follows the path indicated by the small white arrows: from the camera <NUM> it enters into the internal conduit <NUM>, then into the connecting conduit <NUM>, entering in the external portion of the connecting conduit <NUM> that is dashed in the Figure, finally reaching the output conduit <NUM>. The conduit <NUM> is the terminal portion of the connecting conduit <NUM>.

<FIG> shows the condition following the preceding one, wherein, with the activated suction system, the complete opening of the suction valve <NUM> occurs.

The maximal opening of the suction valve <NUM> is obtained with the complete upward flexing of the diaphragm <NUM>, and the simultaneous complete emptying of the camera <NUM>. In such condition, the circulation of air in the conduit <NUM> is stopped, indicated by white dots. This stasis condition, inside the connecting conduit <NUM>, leads to the possible upwelling of liquids/dirt inside the connecting conduit <NUM>, due to turbulences generated at the input point <NUM> of the connecting conduit <NUM>, which is what occurs in the valves according to the known art. Said liquid/dirt can reach the pilot valve <NUM>, blocking its working.

The inventive novelty is the positioning, along the path of the connecting conduit <NUM>, of a non-return valve <NUM> allowing the circulation of air in the direction indicated by the small white arrows in <FIG>.

The non-return valve <NUM> blocks the undesired upwelling of liquid/dirt inside the connecting conduit <NUM>, preventing it from reaching the pilot valve <NUM>, which would jeopardize its working. In case liquids/dirt flow along the connecting conduit <NUM> up to the position <NUM> (<FIG>) at the entry of the connecting conduit <NUM>, they are suctioned/expelled during the successive aperture step of the suction valve <NUM>.

<FIG> shows the successive condition of the suction valve <NUM>, wherein when suction is active, the switching of the closed valve <NUM> occurs, due to the reinsertion of the cannula terminal <NUM> into the assistant's table <NUM>.

The closing of the suction valve <NUM> occurs through the electrical switching of the pilot valve <NUM>, opening the passage of environmental air, coming from conduit <NUM>, and at the same time blocking the connecting conduit <NUM>. In this condition, the atmospheric pressure works on the surface of the diaphragm <NUM> in the chamber <NUM>. The diaphragm <NUM> lowers flexing on the opposed side, also thanks to the depression in the output conduit <NUM>, blocking the passage of air in the conduit.

<FIG> and <FIG> show two magnified views that clarify the working of the preferred embodiment of the present invention, wherein as non-return valve <NUM> there is provided an umbrella valve.

<FIG> shows the moment when the suction valve <NUM> is opening. The umbrella non-return valve <NUM> is in its natural conformation, blocking the passage of liquids from the entry point <NUM> of the connecting conduit <NUM> to the pilot valve <NUM>.

The lip <NUM> is pre-loaded against the surface of the housing <NUM> of the non-return valve, ensuring a seal even with turbulences of the airflow entering in the housing of the non-return valve.

<FIG> shows the moment when the suction valve is opened. The air (indicated by the small white arrows) thrusts on the lip <NUM> of the umbrella non-return valve flexing it, and this allows the passage of air from the connecting conduit <NUM> to the output conduit <NUM>.

It is worth noting that the entry point <NUM> of the connecting conduit <NUM> plays a significant role. Experimentally, it was shown that when said entry point <NUM> is at grade with respect to the output conduit <NUM>, the entry of liquids and dirt is easier. On the other hand, an entry point <NUM> protruding in the output conduit <NUM> reduces the contamination, and, as defined in the present invention, the entry point <NUM> must protrude in the output conduit <NUM> for some millimetres.

The suction valve according to the known art, lacking the non-return valve, works properly only when the input conduit <NUM> is parallel to the ground and/or the output conduit <NUM> is perpendicular to ground. Any tilting with respect to this position worsens the working of the suction valve, so that the entry of dirt/liquid is facilitated into the connecting conduit <NUM>. It was experimentally shown that the suction valve according to the known art works in a better or worse way according to its tilting.

Claim 1:
Suction valve (<NUM>) for dental treatment units (<NUM>), said valve (<NUM>) being connectable through tubings to a suction system placed downstream said dental treatment unit (<NUM>); said suction valve (<NUM>) comprising:
- an input conduit (<NUM>);
- an output conduit (<NUM>) connectable to said suction system;
- said input conduit (<NUM>) and output conduit (<NUM>) being preferably perpendicular;
- a valve seat interposed between said conduits (<NUM>) and (<NUM>);
- a diaphragm (<NUM>) placed transversally to said conduits (<NUM>, <NUM>) defining a chamber (<NUM>) above said diaphragm; said diaphragm (<NUM>) being mobile between two extreme positions, a first resting position wherein the diaphragm adheres against the valve seat blocking the passage of air and liquids between said input conduit (<NUM>) and said output conduit (<NUM>), and a second active position wherein said diaphragm is distanced by said valve seat allowing the passage of air and liquids between said input conduit (<NUM>) and output conduit (<NUM>);
- a connecting conduit (<NUM>) provided with an entry point (<NUM>) protruding in the output conduit (<NUM>) for some millimeters allowing the passage of air between the chamber (<NUM>) and the output conduit (<NUM>);
- an electrically controllable pilot valve (<NUM>), which is switched between a resting position wherein it allows the passage of environmental air to the chamber (<NUM>) through a terminal portion of the connecting conduit (<NUM>) embedded in the body of the suction valve (<NUM>) comprising a first portion (<NUM>), a closing point (<NUM>) and a second portion (<NUM>), and an active position wherein it blocks the passage of the environmental air, connecting the chamber (<NUM>) with the output conduit (<NUM>) through the connecting conduit (<NUM>);
characterized in that,
at the insertion point of the connecting conduit (<NUM>) in said output conduit (<NUM>), there is provided a non-return valve (<NUM>), preventing an input flow to said connecting conduit (<NUM>) from the entry point (<NUM>) and therefore the upwelling of liquids from said output conduit (<NUM>) to said pilot valve (<NUM>) and/or to said chamber (<NUM>).