Patent Application
20090286198
The present invention concerns hand held instruments used, inter alia, by dentists and oral surgeons. The invention concerns more specifically hand held dental instruments for supporting a working tool and driving it in relative movement to operate on or treat a patient.
During operation, it is sometimes necessary to use fluids such as air or water sprayed under pressure to cool the working tool and/or to clean and cool the working area and its vicinity. Hand held dental instruments are therefore connected to a central supply via a feed hose feeding the fluid or fluids under pressure.
Thus hand held dental instruments include internal and/or external passages for conveying the fluid or fluids. These passages have a very small section and there is therefore a risk of them becoming blocked.
It is therefore necessary to filter the fluid or fluids so that they do not contain any polluting particles liable to block the passages of the hand held dental instrument.
A first solution has consisted until now of filtering the fluid or fluids after they leave the central supply. This is the case in particular of the documents U.S. Pat. No. 5,556,279 and U.S. Pat. No. 5,630,939, which propose filtration devices intended to be mounted on the fluid feed pipe between the hand held instrument and the central supply.
However, between these filtration devices and the hand held dental instrument, there are many components constituting the fluid feed path (pipes, fluid-tight connecting areas, . . . ) and there is the risk of particles produced during use of the hand held dental instrument not being filtered, entailing the risk of blocking the passages of the hand held dental instrument. This applies in particular to numerous O-ring seals, in particular in the vicinity of the area for connecting the hand held dental instrument to the feed pipe coming from the central supply. Indeed, successive connections and disconnections produce shear and compression stresses in the O-ring seals and, through abrasion, cause the detachment of polluting particles based on elastomers.
In the absence of a filtration device downstream of the connection between the feed hose and the hand held dental instrument, these particles are entrained by the fluid or fluids and enter the passages of the hand held dental instrument, and if they do not block them, are projected into the mouth of the patient in the vicinity of the working area, causing a critical lack of hygiene.
Thus use has been made of filtration devices mounted directly at the proximal end of the hand held dental instruments, as is the case in the documents EP 1 279 377 and U.S. Pat. No. 6,106,287, for example. There nevertheless still remains a fluid-tight connecting area downstream of these filtration devices and that is also liable to produce polluting particles through successive disconnections/connections of the hand held dental instrument. Moreover, the overall size of these filtration devices is added to the overall size of the hand held dental instrument. This kind of solution is an impediment to the practitioner during operations, there being very little space available for him to work. Such devices do not provide a satisfactory response to the requirements and expectations of practitioners.
Filtration devices integrated directly into the handle of the hand held dental instrument were then proposed, as in the document EP 1 234 548, which uses a cylindrical radial filtration cartridge. This kind of solution necessitates making the handle of the hand held dental instrument longer in order to house the filtration cartridge in it, again increasing the overall size of the hand held dental instrument.
Moreover, all the filtration devices of the documents U.S. Pat. No. 5,556,279, U.S. Pat. No. 5,630,939, U.S. Pat. No. 6,106,287, EP 1 234 548 and EP 1 279 377 function according to the principle of filtration by screening. Filtration by screening is effected by means of a filter with meshes of particular passage section. Particles larger than the passage section of the meshes are retained by the filter while others pass through. The efficacy of the filter is therefore very limited.
Furthermore, because of the accumulation of the retained particles on the filter, filtration by screening induces head losses that can be prejudicial. It is therefore necessary periodically to replace the filters and cylindrical filter cartridges, which leads to a regular waste of time, dismantling and reassembly of the device that are often lengthy and laborious, and the purchase of consumable supplies of non-negligible cost. Because of the long dismantling and reassembly times required by the operation of changing the filters and cylindrical filter cartridges, the practitioner is tempted to delay changing them. This results in a lack of hygiene and in notorious head loss in the fluid passages, the filter or the cylindrical filter cartridge being blocked more than is reasonable.
To remedy these drawbacks, the document U.S. Pat. No. 6,196,841 proposes a plurality of openings provided in a substantially cylindrical section of the handle of the hand held dental instrument. Once again there is filtration by screening with the size of the openings determining the filtration properties, with limited performances.
Moreover, producing this plurality of openings proves fastidious and costly because of the large number of openings of precise size that it is necessary to produce.
A first problem addressed by the invention is to provide simply and at low cost reliable means for filtering the fluid or fluids downstream of the connecting area between the hand held dental instrument and the fluid feed hose, which filtration means must be easily dismantled and cleaned by a qualified technician or by the user himself.
Simultaneously, the present invention aims to provide means for filtering the fluid or fluids in a hand held dental instrument that necessitate no consumables such as a filter cartridge, which avoid the accumulation of impurities in the vicinity of the filtration area, in order not to cause head losses, and which have a very small volume, in order not to increase the overall size of the hand held dental instrument and not to impede the work of the practitioner.
To achieve the above and other objects, the invention proposes a hand held dental instrument for carrying a working tool and driving it in relative movement, including:
wherein:
This kind of hand held dental instrument includes a filtration device that is integrated directly into it, performing filtration as far downstream as possible on the path taken by the fluid.
Filtering is effected for the most part according to a principle of filtration by inertia, more efficient than filtration only by screening and not necessitating the use of consumables such as filters or filter cartridges. There is no addition to the overall size liable to impede the practitioner. Furthermore, it is necessary only to provide a single radial fluids collecting chamber and an attached filtration piece, which proves relatively uncostly.
Preferably, it can be provided that:
Thus there is provision for a further filtering by inertia effect on the upstream side of the radial fluids collecting chamber, in the internal connecting bore.
The fluids transmitted to the hand held dental instrument initially flow along the longitudinal axis of the internal bore of the body connection. In order to enter the fluids conveying channels, the fluids have to follow a path including a 90° bifurcation. Because of their size and their weight, polluting particles, such as seal fragments, cannot make the sudden change of direction, will continue on a course substantially parallel to the longitudinal axis of the internal connecting bore, and will not accumulate in the vicinity of the filtration area. The fluid flowing in the longitudinal direction of the internal connecting bore of the body is therefore filtered laterally. The flow and turbulences in the vicinity of the lateral filtration area expel any polluting particle that might accumulate in the vicinity of the filtration area. This avoids head losses during use of the hand held dental instrument.
The filtration piece advantageously has an exterior shape substantially complementary to the interior shape of the radial fluids collecting chamber, making it easier to determine and control the fluid passage section in the radial fluids collecting chamber, in order to control the fluid flowrate.
Preferably, it can be provided that:
The radial fluids collecting chamber is therefore easy to produce by means of a tool moving radially towards the body of the hand held dental instrument. This provides excellent accessibility for the tool, which greatly facilitates the production of the radial fluids collecting chamber and reduces its manufacturing cost.
Because the back wall of the radial fluids collecting chamber terminates in the near vicinity of the internal connecting bore of the body, the upstream fluids conducting channel extends a very short distance from the internal connecting bore of the proximal section to the back wall of the radial fluids collecting chamber. During filtering, impurities will therefore not tend to accumulate in the upstream fluid conducting channel, but to remain in the internal connecting bore of the body.
This greatly simplifies cleaning the hand held dental instrument: after disconnecting the feed hose from the hand held dental instrument, the practitioner has only to direct a jet of cleaning fluid into the internal connecting bore of the body in order to remove all the polluting particles that may have accumulated therein. Cleaning the hand held dental instrument does not necessitate long and fastidious dismantling and can be carried out very regularly without a notorious waste of the practitioner's time.
Preferably, it can be provided that:
This kind of filtration piece is simple and of relatively low cost to produce.
The filtration piece advantageously includes, in the vicinity of its distal end face:
The peripheral flange with its outside diameter substantially equal to the diameter of the radial fluids collecting chamber facilitates centering of the filtration piece in the chamber, which facilitates mounting the filtration piece. Moreover, depending on the size of their section, the axial grooves can contribute to filtration, for a filtration by screening.
The filtration piece is preferably fixed in the radial fluids collecting chamber with an axial clearance between its distal end face and the back wall of the radial blind bore of the radial fluids collecting chamber, the axial clearance enabling passage of and filtering the fluids between the upstream fluids conveying channel and the downstream fluids conveying channel.
Thus filtering is effected, on the one hand, by the axial clearance between the filtration piece and the back wall of the blind bore of the radial fluids collecting chamber and on the other hand by the difference in diameter between the cylindrical distal filtration section of the filtration piece and the blind cylindrical bore of the radial fluids collecting chamber. This significantly improves the reliability of filtration.
Preferably, it can be provided that:
Thus the filtration piece can be inserted into the radial fluids collecting chamber until its distal end face abuts against the back wall of the blind bore of the radial fluids collecting chamber. Depending on the size of the section of the grooves, the grooves can, through filtration by screening, contribute to filtration.
The filtration piece is advantageously driven into the radial blind bore of the radial fluids collecting chamber with the cylindrical proximal fixing section of the filtration piece a tight fit in the radial blind bore of the radial fluids collecting chamber.
Mounting the filtration piece therefore proves simple and fast. If required, it can be mounted tight so that it cannot be demounted and lost by a user. The filtration piece can nevertheless be removed by a qualified technician provided with the appropriate tools.
Preferably, it can be provided that:
The filtration piece is therefore simple and fast to fit. This kind of filtration piece furthermore proves easily demountable by any person having a screwdriver matching the screwing imprint. The external thread of the proximal fixing section can be indexed so that the filtration piece is mounted in the radial fluids collecting chamber leaving the same axial clearance between the distal end face of the filtration piece and the back wall of the radial blind bore of the radial fluids collecting chamber.
Other objects, features and advantages of the present invention will emerge from the following description of particular embodiments, given with reference to the appended figures, in which:
In the embodiment illustrated in
The first fluids conveying means 6 include an upstream fluids conveying channel 6a, a downstream fluids conveying channel 6b and a radial fluids collecting chamber 6c in the body 1, between the upstream fluids conveying channel 6a and the downstream fluids conveying channel 6b. A filtration piece 7 is fitted into the radial fluids collecting chamber 6c with a clearance that enables passage of and filters fluids between the upstream fluids conveying channel 6a and the downstream fluids conveying channel 6b.
The upstream fluids conveying channel 6a extends radially from the internal connecting bore 2 of the body 1 to the radial fluids collecting chamber 6c, while the downstream fluids conveying channel 6b extends from the radial fluids collecting chamber 6c to the distal end 1b of the body 1.
There is no detachable connecting area downstream of the radial fluids collecting chamber 6c in which the fluid is filtered.
The filtration piece 7 has an external shape substantially complementary to the internal shape of the radial fluids collecting chamber 6c except for a clearance.
It is seen more particularly in the detail view of
The filtration piece 7 used in the embodiment illustrated in
When the hand held dental instrument illustrated in
A fluid under pressure is fed into the internal connecting bore 2. To leave the internal connecting bore 2, the fluid is obliged to exit radially via the upstream fluids conveying channel 6a.
Polluting particles entrained by the fluid, generally of higher density than the fluid, will be incapable of following the flow at the sudden change of flow direction and will remain in the internal connecting bore.
The fluid then enters the radial fluids collecting chamber 6c and escapes from it via the downstream fluids conveying channel 6b.
The filtration piece 7 is fixed in the radial fluids collecting chamber 6c with a small axial clearance j (
As it passes through the radial fluids collecting chamber, the fluid suffers a number of changes of flow direction that constitute as many inertial filtration sites. The polluting particles are sprayed against the filtration piece 7 or against the walls of the radial fluids collecting chamber, and stick thereto.
Depending on the clearance j, complementary filtration by screening can be induced by preventing particles of more or less big size from entering the available volume V of the radial fluids collecting chamber 6c.
The fluid then finally passes through the first fluids conveying means 6 through the body 1 to be transmitted to the fluid spraying means 5 of the head 3.
The upstream fluids conveying channel 6a has a large diameter so as not to induce head losses.
Because of the very short length of the upstream fluids conveying channel 6a, the distal end face 10 induces turbulences in and as far as the mouth of the upstream fluids conveying channel 6a, increasing the filtration by inertial effect during radial filtering from the connecting bore 2 to the fluids collecting chamber 6c. Virtually all, or even all, polluting particles remain in the internal connecting bore 2. Even if a polluting particle is located in the immediate vicinity of the mouth of the upstream fluids conveying channel 6a, it will be driven away from the mouth of the upstream fluids conveying channel 6a on the one hand by the turbulences and on the other hand by the flow in the internal connecting bore 2, the direction whereof is represented by the arrow 15.
After using the hand held dental instrument, its proximal end 1a is disconnected from the driving means and the fluids feed means (not represented). The hand held dental instrument is then in the configuration illustrated in
The mode of operation of the hand held dental instrument illustrated in
The embodiment of the hand held dental instrument illustrated in
This filtration piece 7 is represented in more detail in
In the embodiment illustrated in
An O-ring seal 22 is provided at the periphery of the intermediate section 21 to be slightly compressed against the shoulder 20. The insertion of the filtration piece 7 into the radial fluids collecting chamber 6c is therefore limited not by compression of the O-ring seal 22 but by the intermediate section 21 abutting against the shoulder 20. The effect of this is to prevent deterioration of the O-ring seal 22 through excessive compression and through excessive shear forces.
As an alternative to using an intermediate section 21 abutting against the shoulder 20, it is possible to provide an indexed thread for the filtration piece 7 so that, at the end of screwing it in, the required axial clearance j is preserved between the distal end face 10 of the filtration piece 7 and the back wall 60c.
In the embodiment illustrated in
Alternatively, an opening 23a can be provided in the external body envelope 23 (represented in dashed lines) for accessing the filtration piece 7 and demounting it easily using only a screwdriver. This allows the user to maintain his hand held instrument for himself.
The step of demounting the filtration piece 7 and cleaning the radial fluids collecting chamber 6c is not always required, however, virtually all of the filtration being effected not in the radial fluids collecting chamber 6c but at its inlet. A simpler construction may therefore be preferred, like that shown in
The filtration pieces 7 illustrated in
The outside diameter D4 of the peripheral flange 24 facilitates mounting the filtration piece 7 in the radial fluids collecting chamber 6c by ensuring perfect centering of the filtration piece 7.
Correct centering of the filtration piece 7 in the radial fluids collecting chamber 6c guarantees that the clearance is homogeneous all around the filtration piece 7, which improves filtration.
Depending on the size of the sections of the axial grooves 24a-24d, the latter can participate or not in the filtration of polluting particles in the fluid. Indeed, the fluid will have to pass through the axial grooves 24a-24d to enter completely into the radial fluids collecting chamber 6c and reach the downstream fluids conveying channel 6b.
To enable flow of the fluids from the upstream fluids conveying channel 6a to the downstream fluids conveying channel 6b, the filtration pieces 7 of
Other filtration pieces can still be used. The filtration pieces 7 of
By combining features of the filtration pieces 7 of
The filtration piece 7 of
As for the filtration piece 7 of
In all the embodiments of the hand held instrument illustrated in the figures, and whatever type of filtration piece 7 is used, it is found that filtering the fluids flowing in the body 1 does not increase its overall size at all.
The present invention is not limited to the embodiments that have been explicitly described, but includes diverse variants and generalizations thereof within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 06 53934 | Sep 2006 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2007/053873 | 9/24/2007 | WO | 00 | 3/23/2009 |
