DOUBLE SPRING VALVE WITH MECHANICAL FLAP AND PREHEATING CIRCUIT SO THAT

Description

[0001] The present invention relates to the field of equipment for vehicles with thermal engines or hybrid thermal / electric propulsion, more particularly the treatment of exhaust gases before ejection from these vehicles, and in particular their catalytic treatment. More specifically, it relates to a gas flow control valve for preheating the catalyst or catalytic converter, as well as a preheating circuit for an exhaust system, incorporating such a valve.

[0002] The catalyst or catalytic converter is a component of the exhaust line of motor vehicles with a thermal engine: it is an anti-pollution system whose objective is to reduce the emission of polluting gases.

[0003] Since the combustion of a heat engine is never optimal, toxic substances such as carbon monoxide (CO) or nitrogen oxides (NOX) escape from the engine.

[0004] The catalyst's purpose is precisely to eliminate these gases, which are harmful to health and the environment. It generally consists of a porous ceramic interior impregnated with precious metals (alumina, cesium oxide, palladium, radium). This internal structure is called a "honeycomb."

[0005] Such a catalyst is effective when hot. Indeed, the very high temperature (400 °C) of the exhaust gases causes a catalysis phenomenon (chemical reaction) which eliminates harmful substances. This is why it is installed directly at the engine outlet so as to reach its optimal operating temperature more quickly.

[0006] A vehicle may optionally be equipped with a pre-catalyst and a second downstream catalyst.

[0007] However, 80% of pollutants are emitted in the first 20 seconds of operation of a combustion engine. One solution sought is therefore to have a hot catalyst as soon as the combustion engine starts.

[0008] It is known in the prior art to preheat the catalyst by exposing it to a flow of hot air (for example at least 40°C) and, to do this, to activate a pump, before starting the heat engine or during a first phase of electric rolling, which brings it a flow of hot air, so that it is effective as quickly as possible (to delay as little as possible the possibility of starting the heat engine and allow the emissions control system to reach its maximum efficiency very quickly). This pump is connected to the air filter and will send hot air to the catalyst. The pump generally operates for about thirty seconds, and as soon as the heat engine is started it stops operating, since there is no longer any need to preheat the catalyst.

[0009] Between the pump and the catalyst there is an electric valve with a solenoid valve that will open or close to operate or not this catalyst preheating circuit (see schematic representation of the [ Fig.1A ]).

[0010] In the prior art, the gas flow circulation line connecting the pump to the catalyst is provided with an electric valve (generally a solenoid valve) which will open or close this circuit, depending on the operating phase and the state of the vehicle, to authorize the injection of hot air during the catalyst preheating phase and isolate the pump from the exhaust gases during operation of the heat engine.

[0011] However, this known electric valve solution has a number of disadvantages: it is bulky and complex in construction (presence of an electrical system), has a high cost price for an accessory function, is subject to a risk of malfunction (implementation of electrical components in a high temperature environment) and requires the installation of an electrical connection to the valve.

[0012] The present invention aims to overcome at least the main of these drawbacks, preferably all of them.

[0013] From document US 3122162, a control valve for gaseous fluid is already known which substantially has the constructive characteristics mentioned in the preamble of claim 1. However, this known valve is not suitable for use in the context indicated above.

[0014] The object of the invention is achieved by a control valve for gaseous fluid, suitable and intended to be mounted in a hot gaseous fluid circulation line according to the preamble of claim 1 and having in combination the characteristics of the characterizing part of this claim 1.

[0015] The invention will be better understood from the following description, which relates to a preferred embodiment, given as a non-limiting example, and explained with reference to the appended schematic drawings, in which: [ Fig. 1A ] And [ Fig. 1B ] are simplified schematic representations of hot air preheating circuits for a catalyst of an exhaust system of a vehicle with a thermal engine, respectively with an electric valve according to the state of the art ( figure 1A ) and with a mechanically actuated flap valve according to the invention ( figure 1B ) ; [ Fig. 2A ], [ Fig. 2B ] And [ Fig. 2C ] are sectional and elevation views of a first embodiment of the valve according to the invention, along a plane containing the median flow direction (is also the axis of symmetry of the valve), the valve being respectively at rest ( figure 2A : vehicle stationary, engine off), in the open state ( figure 2B : catalyst preheating phase, before starting the thermal engine) and in the closed state ( figure 2C : thermal engine started, production of exhaust gas); [ Fig. 3 ] is an exploded view of the valve of the figures 2 ; [ Fig. 4 ] is a perspective view of the flapper forming part of the valve figures 2 And 3 ; [ Fig. 5 ] is a perspective view of the arrangement and force transmission part forming part of the valve of the figures 2 And 3 , And [ Fig. 6 ] is a sectional and elevational view of a second embodiment of the valve according to the invention, along a plane containing the median flow direction (is also the axis of symmetry of the valve), the valve being at rest and its flap in an intermediate detachment position.

[0016] THE figures 2 , 3 And 5 illustrate a control valve (1) for gaseous fluid, intended to be mounted in a gaseous fluid circulation line (2), for example of the type shown figure 1B .

[0017] This valve (1) comprises a hollow body (1') forming a housing, which is configured to be crossed by an authorized flow (FGA) of gaseous fluid circulating between an inlet opening (3) and an outlet opening (4) of said housing (authorized circulation direction).

[0018] In this hollow body (1') are mounted a movable valve (5) with a closure member (5') and elastic means (6, 7) acting on said valve (5). Said valve (5) and the elastic means (6, 7) are arranged and configured in such a way that the valve (5) releases the inlet opening (3) in the event of the presence of an authorized gas flow (FGA) and closes said inlet opening (3) in the event of the presence of a gas flow (FGI) tending to circulate in the opposite direction (relative to the authorized gas flow), this by moving its closure member (5') respectively between a position at a distance from the region (3') of the housing comprising said inlet opening (3) - release of the inlet opening - and a position close to, or even in contact with, this region (3') - closure of the inlet opening.

[0019] The elastic means (6, 7) consist of two springs acting in a mutually antagonistic manner on the valve (5) for its displacement, a first spring (6) urging the valve (5) away from the inlet opening (3) and the second spring (7) urging said valve (5) towards said inlet opening (3).

[0020] According to the invention, the force (F7) of the second spring (7) is, on the one hand, at least equal to the force (F6) of the first spring (6) and, on the other hand, less than the sum of the force (F6) of the first spring (6) and the pressure force (FP) of the authorized gas flow (FGA) on the closure member (5') of the valve (5), and said valve (5) is, in the absence of any gas flow, moved and held by the first spring (6) in a detachment position, preferably corresponding just to an absence of contact between the closure member (5') and the inlet opening (3) and / or the region (3') of the latter.

[0021] Thanks to such a construction and the provisions of the invention, a gas flow regulating member (unidirectional flow) of simple, economical and compact structure is obtained, and requiring no energy source or any control (autonomous operation). The valve (1) of entirely mechanical nature provided by the invention also does not need any additional control, electrical or otherwise, nor any control or power supply connection for its operation. Furthermore, it is not sensitive to the heat to which it is exposed during its operation. In addition, by providing a rest position of the valve (5) in which the member (5') is detached (partial release of the opening 3), said member (5') is avoided from sticking by frost and therefore a loss of time before allowing the passage of an authorized gas flow (FGA).

[0022] The two opposing springs (6 and 7) can present, in the range of movement of the valve closure member, opposing elastic stress forces or intensities of substantially equal values, and consequently its rest position in the absence of any gas flow is located substantially halfway between the complete closure position and the total opening position (floating, unwedged position, resulting from a dynamic balance of forces).

[0023] According to one method of construction, the two springs (6 and 7) can both be in contact and act directly on the closing member (5') of the valve (5), as illustrated by way of example in the figure 6 (in the valve's rest position - semi-open position). It can be noted that the member (5') is guided in translation - for example by a guide insert (12') - according to a median direction (DE) of flow for an authorized gas flow (FGA) passing through said hollow body (1') in the direction from the inlet opening (3) to the outlet opening (4), this median direction (DE) being coincident with the central and action axes of the forces of the first and second springs (6 and 7). It can also be noted that the first spring (6) is housed in the inlet opening (3) and that the member (5') has an aerodynamic shape promoting the flow of an authorized gas flow and promoting the movement of this member for a closure of the inlet opening under the action of a reverse gas flow.

[0024] Also in accordance with the invention, and as illustrated by the figures 2 And 3, the valve (1) also comprises a part (8) for arranging and transmitting force, which is mounted movably with guidance in the hollow body (1'), is subjected to the action of the second spring (7) which urges it towards the region (3') of the inlet opening (3), cooperates with the flap (5) and defines the detachment position of the latter. Such a part (8) makes it possible to decouple the action of the second spring (7) on the closure member (5') and to provide a repeatable rest position (detachment). The conditions of occurrence and the physical and mechanical determination of the rest position are thus defined constructively and in a simple, precise and lasting manner, whether the two springs (6 and 7) are of substantially equivalent forces / intensities or not.

[0025] For the sake of constructive simplicity, the arrangement and force transmission part (8) is configured and arranged in the hollow body (1') to be directly subjected to the action of the second spring (7) and to transmit the stress from this spring to the valve (5) when it is in contact with the latter.

[0026] In connection with this embodiment, it is advantageously provided that the force (F7) of the second spring (7) is greater than the force (F6) of the first spring and that said valve (1) comprises a stop means (9) limiting the movement of said part (8) in the direction of the region (3') of the inlet opening (3) - under the action of the second spring of greater force -, and thus determining a set detachment position for the valve (5). Thus, the rest position is repeatedly fixed in a safe and precise manner (cf. figure 2A ).

[0027] In order to favorably limit the size of the valve + spring assembly, the valve (5) and the first spring (6) are housed inside the arrangement and force transmission part (8), the valve (5) being further guided by said part (8) during its movements in the hollow body (1'), which can be carried out in concert with said part (8) or relative to the latter (transition from the rest position to the closed position or vice versa for the valve, in the context of the second embodiment).

[0028] In order to limit the pressure loss for the authorized gas flow (FGA), the valve (5) and the arrangement and force transmission part (8) have hollowed-out and perforated structures so as to offer limited resistance to the flow of an authorized gas flow (FGA) through the interior of the hollow body (1'), preferably a passage section at their level in the housing which is at least equal in surface area to that of the inlet opening (3). Such a passage section can be achieved for example by widening at least locally the section of the hollow body (1') and by providing an essentially perforated construction for the valve (5) and said part (8) - cf. figure 3 .

[0029] As illustrated on the figures 2 , 3 And 6, and in accordance with a preferred, simple and efficient constructive form, the inlet opening (3) and the outlet opening (4) are located mutually opposite, preferably in opposite walls (10, 10') of the hollow body (1'), and define by their mutual alignment a median direction (DE) of flow for the authorized flow (FGA) passing through said hollow body (1') in the direction from the inlet opening (3) to the outlet opening (4). Advantageously, this median direction (DE) coincides with the central axes of the first and second springs (6 and 7) and with the direction of bidirectional translational movement of the valve (5) with its closure member (5') in the hollow body (1'). Thus, the directions of action of all the forces acting on the valve (5) and the part (8) coincide.

[0030] In particular in relation to the aforementioned preferred construction, illustrated for example on the figures 2 , 3 And 6, the valve (5) and the arrangement and force transmission part (8) are mounted to move between them, with the ability to move relative to each other in the median direction (DE) limited unidirectionally by axial stop (contact between valve member 5 and part 8).

[0031] Also in connection with the above-mentioned preferred construction, it may be provided that the first spring (6) consists of a compression spring, bears on the wall (10) having the inlet opening (3), advantageously at the region (3') of the latter, surrounds the closure member (5') and contacts the valve (5) at an annular engagement portion (5") of the latter, which is offset relative to the closure member (5') in the median flow direction (DE). It may further be provided that the second spring (7) consists of a compression spring, bears on the wall (10') having the outlet opening (4) and contacts the arrangement and force transmission part (8) at an annular engagement portion (8') of the latter.Finally, in order to facilitate and secure the cooperation between part (8) and member (5'), the annular engagement part (8') of the arrangement and force transmission part (8) may comprise an imprint (11) configured for substantially wedged reception of the annular engagement part (5") of the valve (5), these two annular engagement parts (5" and 8') advantageously having flat shapes.

[0032] Likewise, in the embodiment shown figures 2 And 3 , the closing member (5') is in the form of a disc provided with a peripheral seal (5"') and closes the inlet opening (3) in the manner of a cover.

[0033] Still in particular in relation to the aforementioned preferred construction, the engagement and force transmission part (8) is advantageously guided in translation in the hollow body (1') in the median flow direction (DE) by cooperation of an engagement part (8') of said part (8) with internal profiled formations (12) of said body (1'), the limitation of the movement of said part (8) in the direction of the region (3') of the inlet opening (3), and therefore the determination of the set separation position for the valve (5), being obtained either by contact of said engagement part (8') with one or more stops at the end of said profiled formations (12) - variant not shown -, or by contact of tabs (8") extending said engagement part (8') with the region (3') of the hollow body (1') comprising the inlet opening (3) - variant shown figures 2 And 6 .

[0034] According to an advantageous practical embodiment, the hollow body (1') is formed of two constituent parts (13 and 13'), preferably made of thermoplastic material, assembled together at a joint plane (PJ), advantageously perpendicular to a median direction (DE) of flow for the authorized flow (FGA) passing through said hollow body (1'), each of said parts comprising one of the inlet and outlet openings (3, 4) and being optionally extended in one piece by a respective connection end piece (13").

[0035] The choice of materials and dimensions of the first and second springs (6 and 7) is the responsibility of a person skilled in the art and will be dictated in particular by the temperature of the gas flows and by the forces to be provided.

[0036] The material(s) of the hollow body (1'), the valve (5) and the part (8) will also depend on the temperatures of the gas flows (for example: between approximately 130°C and 240°C, a thermoplastic material will be used, and for temperatures above 240°C, aluminium or stainless steel will be used).

[0037] The hollow body (1') can also be made of two materials, with one constituent part in aluminum and another part in thermoplastic, if the temperature difference is significant between the two sides of the valve.

[0038] The invention also relates, as shown by way of example, to figure 1B , a preheating circuit for a catalyst exhaust system (15), said circuit comprising a pump (14) injecting hot air into a circulation line (2) which brings it to the catalyst (15).

[0039] According to the invention, this preheating circuit is characterized in that it integrates a control valve for gaseous fluid (1) as described above, the gas flow injected by the pump (14) corresponding to the authorized gas flow (FGA) for this valve (1).

[0040] Of course, the invention is not limited to the embodiments described and shown in the attached drawings. Modifications remain possible, particularly from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention, the scope of protection being defined by the claims.

Claims

1. Control valve (1) for gaseous fluid, intended to be mounted in a gaseous fluid circulation line (2), said valve (1) comprising a hollow body (1') forming a housing, which is configured to be passed through by an authorized stream (FGA) of gaseous fluid circulating between an inlet opening (3) and an outlet opening (4) of said housing and in which are mounted a mobile shutter (5) with a shut-off member (5') and elastic means (6, 7) acting on said shutter (5), said shutter (5) and the elastic means (6, 7) being arranged and configured in such a way that the shutter (5) opens up the inlet opening (3) in the event that an authorized gas stream (FGA) is present and shuts off said inlet opening (3) in the event that a gas stream (FGI) that tends to circulate in the opposite direction is present, this being by movement of its shut-off member (5') respectively between a position at a distance from the region (3') of the housing that has said inlet opening (3) and a position close to, or even in contact with, this region (3'), the elastic means (6, 7) consisting of two springs acting in a mutually opposing manner on the shutter (5) with a view to its movement, a first spring (6) urging the shutter (5) away from the inlet opening (3) and the second spring (7) urging said shutter (5) towards said inlet opening (3), wherein the force (F7) of the second spring (7) is, on the one hand, at least equal to the force (F6) of the first spring (6) and, on the other hand, less than the sum of the force (F6) of the first spring (6) and the pressure force (FP) of the authorized gas stream (FGA) on the shut-off member (5') of the shutter (5), wherein said shutter (5) is, in the absence of any gas stream, moved and held by the first spring (6) in a detachment position, preferentially just corresponding to an absence of contact between the shut-off member (5') and the inlet opening (3) and / or the region (3') of the latter, the valve being characterized in that it also comprises an arrangement and force transmission piece (8), which is mounted so as to be able to move with guidance in the hollow body (1'), is subjected to the action of the second spring (7), which urges it in the direction of the region (3') of the inlet opening (3), cooperates with the shutter (5) and defines the detachment position of the latter.

2. Valve (1) according to Claim 1, characterized in that the arrangement and force transmission piece (8) is configured and arranged in the hollow body (1') so as to be directly subjected to the action of the second spring (7) and to transmit the urging of this spring to the shutter (5) when it is in contact with the latter.

3. Valve (1) according to Claim 1 or 2, characterized in that the force (F7) of the second spring (7) is greater than the force (F6) of the first spring and in that it comprises a stop means (9) limiting the movement of said piece (8) in the direction of the region (3') of the inlet opening (3) and determining a wedged detachment position for the shutter (5).

4. Valve (1) according to any one of Claims 1 to 3, characterized in that the shutter (5) and the first spring (6) are housed inside the arrangement and force transmission piece (8), the shutter (5) also being guided by said piece (8) during its movements in the hollow body (1'), which can be effected together with said piece (8) or relative to the latter.

5. Valve (1) according to any one of Claims 1 to 4, characterized in that the shutter (5) and the arrangement and force transmission piece (8) have hollowed-out and perforated structures so as to offer limited resistance to the flow of an authorized gas stream (FGA) through the inside of the hollow body (1'), preferentially a passage section at their level in the housing that is at least equal in surface area to that of the inlet opening (3).

6. Valve (1) according to any one of Claims 1 to 5, characterized in that the inlet opening (3) and the outlet opening (4) are situated facing one another, preferentially in opposite walls (10, 10') of the hollow body (1'), and define by their mutual alignment a median flow direction (DE) for the authorized stream (FGA) passing through said hollow body (1') in the direction from the inlet opening (3) towards the outlet opening (4), and in that this median direction (DE) is coincident with the central axes of the first and second springs (6 and 7) and with the direction of movement in bidirectional translation of the shutter (5) with its shut-off member (5') in the hollow body (1').

7. Valve (1) according to any one of Claims 1 to 6, characterized in that the shutter (5) and the arrangement and force transmission piece (8) are mounted so as to be able to move relative to each other, with a capability for mutual relative translation in the median direction (DE) that is limited unidirectionally by axial abutment.

8. Valve (1) according to any one of Claims 1 to 7, characterized in that the first spring (6) consists of a compression spring, bears on the wall (10) that has the inlet opening (3), advantageously at the region (3') of the latter, surrounds the shut-off member (5') and contacts the shutter (5) at an annular engagement part (5") of the latter, which is offset relative to the shut-off member (5') in the median flow direction (DE), in that the second spring (7) consists of a compression spring, bears on the wall (10') that has the outlet opening (4) and contacts the arrangement and force transmission piece (8) at an annular engagement part (8') of the latter, and in that the annular engagement part (8') of the arrangement and force transmission piece (8) has an indentation (11) configured for substantially wedged reception of the annular engagement part (5") of the shutter (5), these two annular engagement parts (5" and 8') advantageously having flat shapes.

9. Valve (1) according to Claim 8, characterized in that the engagement and force transmission piece (8) is guided in translation in the hollow body (1') in the median flow direction (DE) by cooperation of an engagement part (8') of said piece (8) with internal profiled formations (12) of said body (1'), the limitation of the movement of said piece (8) in the direction of the region (3') of the inlet opening (3), and therefore the determination of the wedged detachment position for the shutter (5), being obtained either by contact of said engagement part (8') with one or more stops at the end of said profiled formations (12), or by contact of tabs (8") extending said engagement part (8') with the region (3') of the hollow body (1') that has the inlet opening (3).

10. Valve according to any one of Claims 1 to 9, characterized in that the hollow body (1') is formed of two constituent parts (13 and 13'), preferentially made of thermoplastic material, joined together at a joint plane (PJ), advantageously perpendicular to a median flow direction (DE) for the authorized stream (FGA) passing through said hollow body (1'), each of said parts comprising one of the inlet and outlet openings (3, 4) and possibly being extended in a single piece by a respective connection end (13").

11. Preheating circuit for an exhaust system with a catalytic converter (15), said circuit comprising a pump (14) injecting hot air into a circulation line (2) that brings it to the catalytic converter (15), which preheating circuit is characterized in that it integrates a control valve for gaseous fluid (1) according to any one of Claims 1 to 10, the gas stream injected by the pump (14) corresponding to the authorized gas stream (FGA) for this valve (1).