Pneumatic suction device, pneumatic grinding system with such a device and corresponding system

Description

Field of invention

[0001] The field of the invention is that of pneumatic suction devices, and in particular dust extraction devices. Such suction devices can be used to extract dust created by the operation of a tool, such as a pneumatic sander for example.

[0002] More specifically, the invention relates to means for amplifying suction intended to be implemented in such a pneumatic suction device. Prior art

[0003] In the field of automotive body repair, the sanding operation is combined with the use of a dust extraction system to collect sanding particles, including aluminum particles, also known as dust. By being extracted, the particles do not pollute the ambient air in the garage, thus protecting the air quality in the body shop.

[0004] Aluminum dust, once stored, can explode in the presence of a spark (from an electric motor, for example). Therefore, sanders and dust extraction systems used by auto body repair shops must comply with the ATEX standard. This standard is designed for hazardous environments or for sanding specific materials.

[0005] For occasional use or for hard-to-reach areas, we know of complete mobile units consisting of a central vacuum unit (a vacuum device on wheels, for example) and an electric sander.

[0006] To comply with ATEX standards, the electrical components of electric sanders used in these mobile units must be isolated from external elements and, in particular, from the dust extracted. Such isolation is relatively complex and expensive to implement. Consequently, the cost of these sanders is very high, which is a major obstacle to their widespread use. Furthermore, in body shops, mobile sanding equipment is often poorly maintained. Fine particles clog the collection bag and any filters, quickly impairing dust extraction. In addition, the relatively heavy weight of the electric sander negatively impacts its ergonomics.

[0007] Generally, body shops use pneumatic sanders because they are lightweight, easy to handle, and pose no risk when dealing with aluminum particles. Pneumatic sanders are typically connected to a dust extraction system, which is itself connected to a compressed air network within the body shop. Therefore, both the pneumatic sander and the dust extraction system are connected to the body shop's compressed air supply.

[0008] One drawback of this solution is that to achieve optimal performance of the pneumatic sander and dust extraction system, a very high air pressure supply, on the order of approximately 7 bar, is required. However, not all premises equipped with a compressed air supply network are necessarily capable of providing such air pressure.

[0009] Furthermore, the very high air consumption of the sander and dust extraction system can cause disruptions to the entire compressed air network. This can lead to variations in airflow to other tools in the room and result in quality problems, for example, in the case of a pneumatic paint sprayer.

[0010] Indeed, pneumatic suction devices generally employ Venturi-type air suction. Venturi-effect air suction is well-known, as it is widely used in industry for creating a vacuum on suction cup grippers. Since the suction cups do not generate a significant airflow, its use is relatively economical.

[0011] However, when such a solution is implemented in pneumatic dust extraction systems, large Venturi modules are required to ensure sufficient vacuum and suction flow to capture dust. The nozzle orifice of the Venturi module is therefore oversized to draw in a significant volume of air. Consequently, air consumption is very high. For example, when testing such a solution, the applicant observed a sharp drop in air pressure in the compressed air system supplying the entire workshop, with the inlet pressure falling from 7 bar to 3 bar. This resulted in a significantly reduced airflow to the sander and damage to the overall compressed air system of the workshop.

[0012] In other words, this solution is unsatisfactory because it has high air consumption for suboptimal suction performance. Document WO 2005 / 002795 A1 describes a sanding system comprising a pneumatic sander and a pneumatic suction device with an air amplification module operating on the Venturi effect.

[0013] Document FR1191387 describes a solution implementing a Coanda effect type amplifier, but in the field of oil extraction.

[0014] There is therefore a need to provide a new suction solution that allows optimal operation of the suction device when used with a pneumatic sander on a compressed air supply network offering a lower air pressure than in the prior art, for example on the order of 5 bars.

[0015] This solution must also provide high suction performance while offering optimal inlet air consumption, so as not to disrupt the workshop's compressed air supply network. Summary of the invention

[0016] The technique of the invention makes it possible to overcome at least some of the drawbacks raised by the prior art. More specifically, the invention relates to a sanding system having the technical characteristics defined by the subject matter of claim 1.

[0017] According to the invention, said at least one air amplification module comprises at least two air amplifiers operating according to the Coanda effect.

[0018] The implementation of an air amplification module comprising at least two air amplifiers according to the invention makes it possible to provide optimal suction performance, in that the depression created by the air amplifiers is high while maintaining a contained air consumption.

[0019] These optimal performances are achieved in particular by the implementation of a suction device operating solely pneumatically and including air amplifiers operating under the Coanda effect.

[0020] The invention thus provides a suction solution particularly suited to the extraction of dust, and especially aluminum dust. Furthermore, the pneumatic suction device according to the invention complies with the ATEX standard, a standard that must be observed in automotive body shops.

[0021] Thus, the invention proposes a novel and inventive approach to overcoming the drawbacks of the prior art by providing a simple-to-implement suction solution offering high suction performance with optimal air consumption. The invention therefore provides a new suction solution that offers superior performance compared to previously described prior art suction solutions.

[0022] According to the invention, said at least two air amplifiers are arranged in parallel within said at least one amplification module.

[0023] The specific arrangement of the air amplifiers in parallel within the amplification module simplifies airflow through the connecting pipes. Furthermore, this arrangement significantly reduces turbulence at the module's inlet and outlet, further simplifying airflow and minimizing losses in pressure and airflow.

[0024] According to another particular aspect of the invention, said at least one amplification module comprises a base having at least two first bores, called air inlet bores, extending through said base.

[0025] According to yet another particular aspect of the invention, said at least one amplification module comprises a body in which said at least two air amplifiers are formed at least in part, said body comprising for each of said at least two air amplifiers: a second bore, called the air outlet bore, substantially circular or conical, extending from a first side of said body oriented towards said suction nozzle; a fillet, extending said outlet bore and joining walls of said outlet bore and a surface opposite said first side of said body.

[0026] Said at least one amplification module includes, for each of said at least two air amplifiers, a slot adjacent to said fillet, said slot being configured to permit an additional inflow of air into said air amplifier.

[0027] The specific implementation of the inlet bore, outlet bore, fillet and slot allows for optimal performance, thanks in particular to the Coanda effect caused in the air amplifiers.

[0028] According to a particular aspect of the invention, said slot is configured to allow an inlet of compressed / pressurized air.

[0029] The implementation of this slot allows a flow of pressurized air to enter, at a higher speed into the air amplification module than the air flow drawn into the latter, so as to obtain the Coanda effect.

[0030] According to another particular aspect of the invention, said slot is in fluidic communication, on the one hand with said first bore and / or said fillet and, on the other hand with a pressurized air chamber.

[0031] Thus, the air amplification module presents a simple solution for introducing pressurized air into air amplifiers.

[0032] According to a particular aspect of the invention, said slot has a width between 0.05 and 0.1 mm.

[0033] According to another particular aspect of the invention, said fillet has an opening of between 1 and 5 mm.

[0034] The invention also relates to a sanding system, particularly for automotive body shops, comprising a pneumatic sander connected to a pneumatic suction device as described above.

[0035] The low air consumption of the pneumatic dust extraction system according to the invention ensures optimal operation of the sander and other pneumatic tools / devices connected to the workshop's main compressed air supply network. This limits, or even eliminates, any disturbances caused to the workshop's main compressed air supply network by the operation of the dust extraction system.

[0036] The invention also relates to an installation comprising a global compressed air supply network including at least one sanding system as described above. List of Figures

[0037] The invention, and its various advantages, will be more easily understood in light of the following description of an illustrative and non-limiting embodiment thereof, and the accompanying drawings, among which: [ Fig.1] schematically illustrates a pneumatic suction device implementing a suction amplification module according to an embodiment of the invention; [ Fig. 2 ] is a cross-sectional view of a suction amplification module according to an embodiment of the invention; [ Fig.3 ] is a detailed cross-sectional view of an air amplifier implemented in the amplification module of the [ Fig. 2 ] ; ] Fig.4 ] is a detailed view of part of the air amplifier of the [ Fig.3 ] ; And [ Fig. 5 ] schematically illustrates a sanding system for an automotive body shop comprising a pneumatic suction device according to the invention. Detailed description of the invention

[0038] The general principle of the invention is based on the implementation of at least one air amplification module 2 within a pneumatic dust extraction device 1, for example in a body shop.

[0039] Such a device 1, illustrated on the [ Fig.1 ], includes a suction unit 10 supplied with pressurized air, or compressed air, by air supply pipes 14 connected to a global compressed air supply network 8 of the workshop in which the suction device 1 is used.

[0040] The central vacuum unit 10 is connected to a suction nozzle 12 via suction pipes, or connecting pipes, 13.

[0041] The suction device 1 includes at least one air amplification module 2 (only one module in the example illustrated on the [ Fig.1]), positioned / located between the suction unit 10 and the suction nozzle 12. The amplification module 2 is arranged in the suction pipe 13 such that the entire incoming airflow drawn in by the suction nozzle 12 passes through the air amplification module 2 to reach the suction unit 10. Preferably, the air amplifier module 2 is located close to the suction nozzle 12.

[0042] In one variant, it is possible to implement a plurality of air amplification modules 2 between the suction unit 10 and the suction nozzle 12. In this case, the air amplification modules 2 are arranged in series and are, for example, regularly spaced from each other in the suction pipes 13.

[0043] According to the invention, each air amplification module 2 comprises at least two air amplifiers 21 operating according to the Coanda effect. According to studies carried out in the field, an air amplifier 21 operating according to the Coanda effect makes it possible, when used in air aspiration, to triple the aspiration flow rate at the outlet of the air amplifier.

[0044] Preferably, the air amplifiers 21 are arranged in parallel in the air amplifier module 2, i.e., the airflow entering the air amplifier module 2 is divided in two to pass through the air amplifiers 21. In other words, part of the incoming airflow passes through one of the amplifiers 21 while another part of the incoming airflow passes through the other of the amplifiers 21.

[0045] The specific arrangement of the air amplifiers 21 in parallel within the amplification module 2 simplifies the airflow in the suction pipes 13. Furthermore, this arrangement of the air amplifiers 21 within the amplification module 2 significantly reduces turbulence at the inlet and outlet of the amplification module 2, thereby further simplifying the flow and limiting losses in vacuum and / or airflow, in particular.

[0046] In this example, the division of the airflow is equal / balanced. In other words, the incoming airflow through each amplifier is equal; that is, half of the incoming airflow passes through one of the amplifiers 21 while the other half passes through the other amplifier 21. It is also possible to divide the incoming airflow into unequal parts.

[0047] The division of the incoming airflow into the air amplification module 2 is a function of the structure of the base 20 (described below) of the air amplification module 2. Indeed, it is possible to manufacture / machine the base 20 to divide the incoming airflow as desired.

[0048] The type of air amplifier (here, a Coanda effect amplifier) ​​and the specific arrangement of the air amplifiers 21 within the air amplification module 2 (here, in parallel) make it possible to obtain a suction device 1 that maintains a high airflow rate while preserving optimal vacuum. Thus, the airflow rate of the suction device 1 according to the invention facilitates the suction of dust at the nozzle 12, which can, for example, be in the form of holes in the pad of a pneumatic sander (not shown). Furthermore, the vacuum provided by the suction device 1 according to the invention allows for optimal dust extraction (regardless of its size) and its efficient transport to the dust collection / storage means.

[0049] It should be noted that Coanda effect amplifiers, in their typical use, provide a low airflow rate for a high vacuum. Furthermore, they have the drawback of a decrease in vacuum as the airflow rate increases. A Coanda effect air amplifier was therefore clearly not intended for use in a dust extraction system, which requires high airflow and vacuum. It is the use of at least two Coanda effect air amplifiers in parallel that allows for unexpected performance levels compatible with use in a vacuum system.

[0050] Thus, the suction device 1 according to the invention provides a solution exhibiting low inlet air consumption, good suction flow rate and good vacuum.

[0051] The dimensions of the 21 air amplifiers can be selected according to the application, system or workshop constraints and user requirements in terms of air flow, vacuum and inlet air consumption.

[0052] There [ Fig. 2 ] illustrates in cross-section and in isolation an air amplification module 2 according to the invention.

[0053] The air amplification module 2 includes a base 20, for example made of a metallic or plastic material. The base 20 can be machined / formed at one end to provide a connection housing 201 for a suction hose 13. The connection housing 201 is located on the side of the air amplification module 2 facing the suction nozzle 12 of the device 1.

[0054] An outer surface 202 of the base 20, located near the second end of the air amplification module 2, can be configured to allow a connection with another suction pipe 13, this other suction pipe 13 being the one located / oriented on the side of the suction unit 10 of the suction device 1.

[0055] In one variant, the air amplification module 2 can be integrated or fitted into a suction pipe 13. The connection housing 201 as well as the external surface 202 can therefore then be adapted / modified.

[0056] The base 20 includes a main air inlet 203 which then divides into two inlet bores 204. The inlet bores, or first bores, 204 are substantially circular or conical. It is the inlet bores 204 that divide the airflow entering the air amplifier module 2 into two parts and direct each part of the incoming airflow towards the air amplifiers 21.

[0057] The base 20 of the air amplification module 2 also includes at least one pressure chamber 205 provided near each inlet bore 204. In this example, two circular pressure chambers 205 are implemented near each inlet bore 204, preferably on either side of it.

[0058] The base 20 is configured to cooperate with a body 210 carrying air amplifiers 21. More specifically, the base 20 and the body 210 are configured such that the air amplifiers 21 are each located opposite an air inlet bore 204.

[0059] The air amplifiers 21 and the inlet bores 204 are fluidically connected to allow the intake air, i.e., the air entering the air amplifier module 2, to pass through the inlet bore 204 and then the air amplifier 21 without air loss. In other words, the air amplifiers 21 are placed / fixed in the air amplifier module 2 in an airtight manner within their respective receiving housings.

[0060] In the example shown on the [ Fig. 2Since the air amplifiers 21 are identical, they are described only once. It is understood that the air amplifiers 21 used in an air amplification module 2 of the invention are identical, or at least identical in their structure and operation. However, in variations not shown, they may have different dimensions.

[0061] The air amplifiers 21 are machined / formed in a body 210. The body 210 includes, for each air amplifier 21, a second bore, called the outlet bore, 212, located at a first end 215 of the air amplifier 21, that is, at the end oriented towards the air outlet side of the air amplifier module 2, or in other words, towards the suction unit 10 of the suction device 1. The air outlet bores 212 are substantially circular or conical. The outlet bore 212 extends substantially through the entire body 210, that is, from one end to the other.

[0062] There [ Fig.3 ] illustrates in more detail an air amplifier 21 within the air amplifier module 2.

[0063] As illustrated, the outlet bore 212 is extended by a fillet 213 which connects the surface of the outlet bore 212 with the lower surface 216 of the air amplifier 21, that is to say the surface of the air amplifier 21 located on the side of the air inlet into the air amplifier 21.

[0064] The fillet 213 is configured to cause / form a narrowing of the air passage orifice between the inlet bore 204 of the amplifier module 2 and the outlet bore 212 of the air amplifier 21 in order to achieve the desired Coanda effect.

[0065] Fillet 213 has a large radius and is chosen to optimize the performance of the Coanda effect. Fillet 213 also has an opening, or thickness, e1 (represented on the [ Fig.4 ]) including, for example, approximately between 1 and 5 mm, depending on the dimensions of the air amplifier 21 and the desired performance.

[0066] For example, the 213 fillet preferentially has an opening e1 of 3 mm.

[0067] A slot 214, formed at the junction between the base 20 of the amplification module 2 and the body 210 of the amplifier, connects at least one pressure chamber 205 with the inlet bore 204. In other words, the slot 214 constitutes a supplementary / additional air inlet in the air amplifier 21. This additional air inlet is positioned substantially perpendicular to the longitudinal axis of the inlet bore 204 and outlet bore 212.

[0068] More specifically, slot 214 is adjacent to fillet 213 of air amplifier 21. The geometry of slot 214 is chosen to optimize the performance of the Coanda effect. For example, slot 214 has a width, or thickness, e2 (represented on the [ Fig.4]) between approximately 0.05 and 0.1 mm, depending on the dimensions of the air amplifier 21 and the desired performance.

[0069] For example, slot 214 preferentially has a width e2 of 0.07 mm.

[0070] The slot 214 therefore allows compressed air, i.e. air under pressure, to enter at the level of the fillet 213, between the inlet bore 204 and outlet bore 212, so as to obtain the desired wall effect (i.e. the Coanda effect).

[0071] The Coanda effect obtained within the air amplifier 21 thus accelerates the air within the air amplifier 21. This, in turn, increases both the vacuum and the airflow rate in a straightforward manner. The implementation of two air amplifiers 21, as described above, therefore improves the suction performance of the suction device 1.

[0072] The airflow within the air amplification module 2 is schematically illustrated on the figures 2 to 5 .

[0073] The air drawn in by the suction nozzle 12 is conveyed to the amplification module 2 by the suction pipes 13 (as illustrated in the [ Fig.1 ]). The air drawn in by the suction nozzle 12 constitutes an inlet airflow 31. The inlet airflow into an air amplifier 21 may represent only a part of the overall inlet airflow 31 entering the amplification module 2, since the amplification module 2 comprises at least two air amplifiers 21 arranged in parallel, as described previously.

[0074] The pressure chamber 205 is connected to the overall compressed air supply network 8 (illustrated on the [ Fig.1 ]) and provides, via the slot 214, an additional flow of incoming air 32 under pressure at the junction between the inlet bore 204 and the fillet 213.

[0075] At the outlet of the air amplifier 21, i.e., at the outlet bore 212, the outlet flow 33 is therefore constituted by the sum of the inlet flow 31 and the additional inlet air flow 32 under pressure. The velocity of the outlet flow 33 is greater than the inlet velocity of the inlet flow 31 due to the constriction formed by the fillet 213 and the inlet of additional air 32 under pressure.

[0076] We notice on the figures 3 and 4 that the additional incoming airflow 32 under pressure introduced through the slot 214, between the inlet bore 204 and the fillet 213, creates an acceleration and a "pinning" of the airflow against the wall of the outlet bore 212. The airflow represented by the arrow 321 sticks almost to the wall of the outlet bore 212, also causing induced airflows (not shown) which therefore accelerate the entire outlet flow 33 at the outlet of the air amplifier 21.

[0077] In other words, the air sent under pressure through the slot 214 remains close to the walls of the outlet bore 212. The air velocity on the walls of the outlet bore 212 therefore draws air into the center of the outlet bore 212 by entrainment, as illustrated by the arrows 331.

[0078] The inlet airflow 31 and outlet airflow 32 transport the aspirated dust to the suction nozzle 12. The acceleration of the flows provided by the air amplifiers 21 makes it possible to efficiently transport the dust from the suction nozzle 12 to the suction unit 10, without loss of suction.

[0079] Air amplifiers 21 also make it possible to provide sufficient vacuum and optimal airflow to move / transport aluminum dust, especially when such a suction device is implemented with a pneumatic sander in a body shop. Other aspects and variations of the invention

[0080] The 204 inlet bore of amplifier module 2 includes, on the figures 2 to 4 a single, circular portion. In an unillustrated variant, the input bore 204 of the amplifier module 2 could comprise a first conical portion extended by a second circular portion. It is understood that the reverse would also be conceivable. Other variants, i.e., in the number of portions and in shape, can be considered without departing from the general principle of the invention.

[0081] The same applies to the outlet bore 212 of the air amplifier 21. In the illustrated example, it has a single, conical portion. Other variations, i.e., in the number of portions and in shape, can be considered without departing from the general principle of the invention.

[0082] In an alternative design (not shown), the air amplifiers can be manufactured as a single piece incorporating both the inlet and outlet bores and designed to work with the base. The base of the amplifier module is then adapted to receive the amplifiers and direct the incoming airflow to each of them.

[0083] In another variation, the air amplifier module is machined to directly integrate the air amplifiers. In other words, the base and body are manufactured as a single piece. The air amplifier module is essentially a single unit.

[0084] In yet another variant, the air amplification module is made of several pieces assembled together to form the inlet and outlet bores, the fillet and the slot.

[0085] Each air amplifier 21 can be fluidly connected to one or two pressure chambers 205 supplied with pressurized air, as illustrated in the figures 2 to 4 .

[0086] There [ Fig. 5 [Figure 9] schematically illustrates a sanding system for an automotive body shop comprising a pneumatic sander 91 connected to a pneumatic dust extraction device 1 as described previously. The sander 91 and the dust extraction device 1 are connected to the main compressed air supply network 8. The pneumatic dust extraction device 1 provides high suction performance without significant air consumption on the main compressed air supply network 8. Therefore, the operation of the sanding system 9 does not interfere with other pneumatic tools / devices used on the workshop's network 8.

[0087] During the development of the pneumatic suction device of the invention, the applicant had the opportunity to test and compare prior art suction devices. In particular, the applicant was able to test and compare the suction device of the invention with a pneumatic suction device operating with a Venturi-type amplifier and with an electric suction device.

[0088] These tests revealed that the suction device according to the invention achieves suction performance at least as high as that of prior art suction devices. Most importantly, these tests showed that the suction device according to the invention consumes a significantly smaller quantity of inlet air to achieve the same suction performance.

Claims

1. A sanding system (9), in particular for a car body workshop, comprising a pneumatic sander (91) connected to a pneumatic suction device (1) comprising a suction nozzle (12) connected to a suction unit (10) and at least one air amplification module (2) located in at least one hose (13) for connecting said suction nozzle (12) to said suction unit (10), characterised in that said at least one air amplification module (2) comprises at least two air amplifiers (21) operating according to Coanda effect, said at least two air amplifiers (21) being disposed in parallel within said at least one amplification module (2).

2. A sanding system (9) according to claim 1, characterised in that said at least one amplification module (2) comprises a base (20) having at least two first bores (204), called air inlet bores, extending through said base (20).

3. A sanding system (9) according to claim 2, characterised in that said at least one amplification module (2) comprises a body (210) in which said at least two air amplifiers (21) are formed at least in part, said body (21) comprising for each of said at least two air amplifiers (21): - a second bore (212), called air outlet bore, substantially circular or conical, extending from a first side of said body (21) oriented towards said suction nozzle (12); - a fillet (213), extending said outlet bore (212) and making junction between walls of said outlet bore (212) and a surface (216) opposite to said first side of said body (210); said at least one amplification module (2) comprising, for each of said at least two air amplifiers (21), a slot (214) adjacent to said fillet (213), said slot (214) being configured to enable an additional air intake in said air amplifier (21).

4. A sanding system (9) according to claim 3, characterised in that said slot (214) is configured to enable a compressed / pressurised air intake.

5. A sanding system (9) according to claim 3 or 4, characterised in that said slot (214) is in fluid communication, on the one hand with said first bore (204) and / or said fillet (213) and, on the other hand, with a pressurised air chamber (205).

6. A sanding system (9) according to one of claims 3 to 5, characterised in that said slot (214) has a width (e2) comprised between 0.05 and 0.1 mm.

7. A sanding system (9) according to one of claims 3 to 6, characterised in that said fillet (213) has an opening (e1) comprised between 1 and 5 mm.

8. A facility comprising a general compressed air supply network (8) comprising at least one sanding system (9) according to one of claims 1 to 7.