ENGINE CONTROL VALVE PROVIDED WITH AN IMPROVED OPENING

Abstract

The invention relates to an engine control valve, having a body delimiting an internal conduit and comprising a shutter (1) having an axis (2) of rotation separating said shutter (1) into a first portion (3) and a second portion (4), said shutter (1) being pivotably mounted in said conduit between a fully opened position allowing the flow of fluid in the conduit, and a closed position preventing said flow, and for which the first portion (3) comes into abutment against a seal (8) rigidly connected to the inner structure of the valve, said seal (8) being provided with an opening (11) equal to the cross section of the gas passage in the conduit. The seal (8) has an extension (12) which projects into the opening (11) in such a way as to partially cover said opening (11).

Description

The invention relates to an engine control valve. This type of valve can for example be fitted to a gas supply circuit of a thermal engine of a vehicle to regulate the flow of EGR (Exhaust Gas Recirculation) gas in a loop enabling a portion of the exhaust gas outputted from the motor to be drawn off and reinjected upstream of said engine. The operating principle of this type of valve is based on the commanded rotation of a shutter, which can move from a fully open position enabling the fluid to pass to a closed position preventing the fluid from passing. The invention relates to a fluid circulation valve with an improved opening mechanism.

An engine control valve therefore has one shutter, which is mounted pivotably on an axis of rotation, such that said axis divides the shutter into a first portion and a second portion. It should be specified that there is no physical limit forming the border between the first and second portions of the shutter. It is assumed that these two portions are separated nominally by a plane passing through the axis of rotation of the shutter and crossing said shutter perpendicularly. The internal structure of the valve in which the shutter is assembled includes a seal. When said shutter is in a closed position, the first portion of said shutter comes into contact with this seal, while the second portion is flush with said seal, leaving a clearance of several tenths of millimeters with said seal.

With reference to FIG. 1, which is drawn showing the mass flow rate of the gas as a function of the opening angle of the shutter of the valve, a problem often encountered with this type of valve is that for small opening angles of the shutter, the gas flow rate initially increases too quickly, then stagnates for a short while, before increasing again regularly if the opening angle of the shutter continues to increase.

Indeed, the curve 100, showing the mass flow rate of the gas flowing through the valve as a function of the opening angle of the shutter, initially shows a first very steep zone 101 corresponding to a sudden increase in the flow rate within an angular range of between approximately 0° and 5°, followed by a second zone 102 comparable to a plateau and corresponding to an angular range of between approximately 5° and 10°, said curve 100 ending with a third approximately linear zone 103, showing a substantially proportional progression of said flow rate as a function of the opening of the shutter within an angular range greater than approximately 10°. The two other curves 105, 106 shown on the diagram represent a linear variation of the mass flow rate of the gases passing through other types of valves, as a function of the opening angle of the shutter of said valves, throughout the possible angular opening range of said shutter. These two curves show the variation of the gas flow rate that would be desirable with the valve according to the invention.

An engine control valve according to the invention has a seal that has undergone a structural modification to limit the gas flow rate for small opening angles of said shutter. As such, the gas flow rate passing through said valve will be linear throughout the angular opening range of the shutter, thereby eliminating the sudden-increase phase of this flow rate observed for very small opening angles, as well as the stagnation phase of this flow rate following this sudden increase. A valve according to the invention thereby ensures a progressive increase of the gas flow rate that is smooth with no starts, thereby enabling better control of this flow rate when compared to existing valves.

The invention relates to an engine control valve, having a body delimiting an internal conduit and comprising a shutter having an axis of rotation dividing said shutter into a first portion and a second portion, said shutter being pivotably mounted inside said conduit between a fully opened position allowing the fluid to flow in the conduit, and a closed position preventing said flow, and for which the first portion butts against a seal, said seal being provided with an opening enabling the gas to flow through the conduit. The seal has an extension which projects into the opening in such a way as to partially cover said opening. The objective of such an extension of the seal is to reduce the flow area of the gases when the shutter pivots open, in order to mitigate the increase in the gas flow rate over the first few degrees of opening of said shutter, and therefore to eliminate the stagnation phase following this sudden increase of said flow rate. Accordingly, throughout the entire opening phase of the valve corresponding to a progressive pivoting of the shutter from the closed position thereof, the increase in the gas flow rate in said valve is regular, with no changes in inclination. The seal can for example be annular or rectangular, the opening of said seal corresponding approximately to the gas flow area in the conduit. The term “approximately” means the opening can be slightly smaller than the gas flow area in the conduit, without however changing the flow characteristics of said gases in the valve. The extension, which is intended to reduce the dimensions of the original opening of the seal, may be made of a separate part joined to the seal, or be manufactured at the same time as said seal, forming therewith a single part. The first part of the shutter is designed ideally to bear against the seal, to ensure a fully airtight closure of the valve. When the valve is in closed position, the extension comes back into contact with the first portion of the shutter by being located upstream of said first portion in consideration of the flow direction of the gas, causing said extension to at least partially protect said first portion of the shutter from said incident gases.

The extension may form a surface extending exclusively in a plane parallel to the seal.

Alternatively, the extension may form a surface extending exclusively in the same plane as the seal.

The extension may form a surface projecting exclusively into the opening.

The extension may form a non-flexible surface.

The extension may define an edge projecting into the opening and extending in a direction forming an intersection with two contiguous edges of the opening.

Advantageously, the extension reduces the opening of the seal by at least 15%. Indeed, this reduction in the opening needs to be sufficiently large to obtain a certain proportionality between the degree of opening of the shutter and the value of the flow rate, in particular for the first degrees of opening of same. However, this reduction should not be so great as to create a bottleneck in the valve, which could have a negative effect and which could compromise the flow conditions of the gas in the valve.

Preferably, the opening resulting from the seal, in the presence of the extension, has a smooth outline. Indeed, the resulting reduced opening should not have an uneven outline with points, protruding edges or sharp hollows that are liable to cause local disturbances to the gas flow in the valve by creating localized eddies or heterogeneous pressure zones.

The overall shape of the opening resulting from the seal, in the presence of the extension, may be a polygon with at least five sides and three consecutive right angles.

Alternatively, the overall shape of the opening resulting from the seal, in the presence of the extension, may be a polygon with at least four sides and three consecutive right angles.

Preferably, the opening is rectangular, the extension being triangular and coming out of at least one edge of the seal surrounding said opening. This shape of the extension is easy to manufacture and is perfectly suited to the problem being addressed.

Advantageously, the extension is a right triangle and is joined to at least two edges of the seal surrounding the opening. In this way, the extension helps to reduce the opening of the seal, without creating breaks or rough edges liable to adversely affect the gas flow in the valve.

Preferably, the extension and the seal form a single part. The resulting seal can therefore be manufactured in a single operation with precision and control.

Preferably, some material has been removed from the first portion of the shutter in a zone of which the outline corresponds to the outline of the extension of the seal, such as to enable said extension to be placed in said zone when the shutter is in a closed position. Indeed, when the shutter is in a closed position in which it blocks the conduit, the first portion must interact closely and ideally with the seal to ensure it is completely airtight. This removal of material from the first portion of the shutter enables the extension of the seal to be placed optimally against said first portion when the shutter is blocking the conduit of the valve. Such an arrangement, in which the extension of the opening and the first portion of the shutter cooperate closely, enables the problem related to the sudden increase in the gas flow rate for small opening angles of the shutter to be addressed optimally.

Advantageously, the extension may engage, when the shutter is in closed position, a flat contact with the first portion of the shutter.

Advantageously, the seal has a prolongation intended to interact with the second portion of the shutter. Indeed, the second portion of the shutter is made flush with this prolongation of the seal when the shutter is in a closed position, leaving a minimal clearance of a few tenths of millimeters. It is assumed that the seal is flat and thin overall. In order to facilitate understanding of the invention, this prolongation corresponds to the second portion of the seal described in the detailed description.

Advantageously, the prolongation of the seal has a second opening. When the shutter is in the closed position against the seal, a pressure imbalance is created around the first portion of said shutter on account of the gas flows impacting said first portion, such that said first portion tends to be pushed and slightly opened. The secondary opening located in the prolongation of the seal is intended to create a depression behind the second portion of the shutter, which then tends to be suctioned by said depression. As the movement dampened by this second portion opposes the movement of the first portion, it plays a compensatory role to prevent said shutter from deforming and to enable it to retain a resulting linear profile in order to ensure good airtightness when it is in a closed position.

Preferably, the prolongation of the seal has a rib, the secondary opening being formed in said rib. The fact that the secondary opening is formed within this rib increases the depression surface thus created by said opening, and helps to ensure a particularly airtight closing of the shutter. Preferably, the secondary opening occupies a central position in the prolongation.

The valves according to the invention have the advantage of providing good control over the gas flow rate throughout the entire opening range of the shutter, in particular by providing a regular, linear increase in the gas flow rate over a reduced angular opening range of the shutter. The valves according to the invention have the advantage of being more efficient than existing regulating valves on account of this improved control of the gas flow rate, while remaining the same size and easy to manufacture.

A detailed description of a preferred embodiment of a valve according to the invention is provided below with reference to the attached drawings, in which:

FIG. 1, already described, is a diagram showing the mass flow rate of the gas passing through a regulating valve in the prior art as a function of the opening angle of the shutter thereof,

FIG. 2 is a perspective view of a seal of an engine control valve according to the invention,

FIG. 3 is a perspective view of a shutter of an engine control valve according to the invention,

FIG. 4 is a perspective view of a shutter and a seal of an engine control valve according to the invention,

A gas circuit of a thermal engine of a motor vehicle includes an upstream gas-supply portion of said engine, through which flows in particular fresh air, and a downstream exhaust portion through which flow the combusted gases to be discharged outside the vehicle. Generally, such a gas circuit includes at least one exhaust gas recirculation (EGR) loop joining the downstream exhaust portion to the upstream supply portion, to enable the exhaust gases to be mixed with the incident fresh air. Since these EGR loops should not be left open permanently during all of the operating phases of the engine, they are each fitted with an EGR valve enabling the flow of exhaust gases flowing through the loop in question to be regulated.

An EGR valve according to the invention includes a gas circulation conduit and a shutter 1, that is mounted pivotably on an axis of rotation 2 and is able to move between a closed position in which it prevents the exhaust gases from flowing, and a fully opened position in which it enables this flow at a maximum rate. The control mechanism of the shutter 1 enables said shutter 1 to be set to any intermediate position between these two end positions.

With reference to FIG. 3, the shutter 1 is mounted on the axis 2 such that said axis 2 divides said shutter 1 into a first portion 3 and a second portion 4. Said portions 3, 4 are flat and thin, and are arranged continuously in relation to one another. Preferably, they form a single part. These two portions 3, 4 have the same width, said width being the dimension thereof measured along the axis of rotation 2, while the first portion 3 is shorter than the second portion 4, the length being the dimension thereof measured along an axis perpendicular to said axis of rotation 2. The first portion 3 and the second portion 4 are joined rigidly to one another, such that they pivot simultaneously about the axis 2 and are arranged at 180° from one another. The second portion 4 of the shutter 1 is rectangular and of constant thickness. The first portion 3 of this shutter 1 includes a substantially rectangular supporting part 5 of constant thickness, surmounted by a substantially rectangular joining part 6 having a shaped thickness, said joining part 6 joining the second portion 4 of the shutter 1 to the supporting part 5. Indeed, this joining part 6, positioned in contact with the supporting part 5, ideally extends the second portion 4 of the shutter 1, the thickness at the junction plane 7 between same being the same, the thickness of this joining part 6 decreasing progressively as it moves away from said junction plane 7 in a direction perpendicular to this plane 7. It should be specified that the junction plane 7 is parallel to the axis of rotation 2 of the shutter 1. The dimensions of the supporting part 5 are greater than the dimensions of the joining part 6 where they contact, such that the thickness of the U-shaped peripheral portion of the first portion 3 of the shutter 1 is the same as the thickness of this supporting part 5. Preferably, the second portion 4 of the shutter 1 and joining part 6 form a single part. Indeed, the concept of “joining part” has been included with a view to describing the shutter 1 as accurately as possible, without suggesting that this part is necessarily separate. The same is true of the two portions 3, 4 of the shutter 1, which correspond to the two portions of the shutter 1 located on either side of the axis, but that do not necessarily have a marked and visible physical limit.

With reference to FIG. 2, once the shutter 1 has been placed inside the valve, it cooperates with a seal 8 that is rigidly connected to the internal structure of said valve, to ensure said valve is airtight when the shutter 1 is in closed position. The seal 8 is a flat, thin part that has an overall rectangular shape, making it possible to distinguish a first portion 9 and a second portion 10, said second portion 10 being referred to as the prolongation in the claims. The first portion 9 is rectangular and extends in a direction perpendicular to the longitudinal axis of said seal 8. In other words, the longitudinal axes of the seal 8 and of the first portion 9 are perpendicular. This first portion 9 includes an opening that, for a seal in the prior art, is rectangular and of which the dimensions are close to the dimensions of the flow area of the gases in the conduit of the valve. For an EGR valve according to the invention, this opening 11 has been reduced by means of an extension 12 of the seal that projects into said opening 11, said extension 12 being a right triangle. More specifically, the two perpendicular sides 13, 14 of this extension 12 are in contact with the two perpendicular edges 15, 16 delimiting the opening, each of said sides 13, 14 being shorter than the length of the edge 15, 16 against which it bears. Advantageously, this extension 12 and the seal 8 are made of the same material and form a single part, and said sides 13, 14 and said edges 15, provide perfect continuity and cannot be distinguished. The resulting opening 11 therefore has an end 17 of constant width over a short length, said width decreasing progressively along the remainder of the length of said opening 11 as it moves away from said end 17 of constant width, before reaching a minimum non-zero value. The second portion 10 of the seal 8 is rectangular and extends in a direction perpendicular to the longitudinal axis of said seal 8. In other words, the longitudinal axes of the seal 8 and of the second portion 10 are perpendicular. This second portion 10 is full overall, and has a recess 18 in the form of a rectangular slot extending parallel to the second portion 10 of the seal 8. This slot 18 occupies a central position in the second portion 11 of the seal 8. This second portion 10 is provided with a secondary opening 19, comparable to a circular orifice, said orifice 19 being located at the center of the slot 18. The dimensions of this orifice 19 are clearly less than the dimensions of the opening 11 of the first portion 9, the ratio between the surface areas of same varying between 10 and 20.

With reference to FIG. 2, material has been removed from the joining part 6 of the shutter 1, the outline of same being triangular and having the same dimensions as the extension 12 of the seal 8. Thus, said joining part 6 has an oblique edge 20. Once in closed position in the valve, the first portion 3 of the shutter 1 can be positioned against the first portion 9 of the seal 8, such that the extension 12 of the seal 8 can be seated in the shape of said first portion 3 formed by this removed material.

With reference to FIG. 4, the shutter 1 is mounted in the valve such that the first portion 3 cooperates with the first portion 9 of the seal 8, and such that the second portion 4 cooperates with the second portion 10 of the seal 8, the axis of rotation 2 of said shutter 1 forming the division between the two portions 9, 10 of the seal 8. When the shutter 1 returns to a closed position, the first portion 3 comes into contact with the first portion 9 of the seal 8, such that the extension 12 of the seal 8 is in contact with said first portion 3 in the seat created by the removed material. Simultaneously, the second part 4 of the shutter 1 is made flush with the second portion 10 of the seal 8, leaving a few millimeters clearance. The secondary opening 19 formed in the second portion 10 of the seal 8 makes it possible to create a depression intended to suction the second portion 4 of the shutter, in order to compensate for the movement of the first portion 3 of the shutter 1. Indeed, when the valve is in a closed arrangement, the gases located upstream of the shutter 1 exert a pressure on the first portion 3 of said shutter 1, which tends to be pushed back and to open slightly, allowing a small fraction of the gases to flow through. The depression helps to move the second portion 4 of the shutter 1 in a direction opposite the direction of the first portion 3, enabling said shutter 1 to retain a linear profile and thereby to ensure the closure is properly airtight.

Accordingly, such a reduction of the opening 12 of the first portion 9 of the seal 8, combined with an adapted profile of the first portion 3 of the shutter 1, makes it possible to limit the gas flow during the first degrees of opening of the shutter 1 from the closed position thereof. Consequently, the gas flow rate increases linearly with the degree of opening of the shutter 1, throughout the entire angular opening range of said shutter 1. Such a valve makes the gas flow rate proportional to the angular degree of opening of the shutter throughout the possible opening range of the shutter 1.

Claims

1. An engine control valve, having a body delimiting an internal conduit and comprising: a shutter having an axis of rotation dividing said shutter into a first portion and a second portion, said shutter being pivotably mounted inside said conduit between a fully opened position allowing the fluid to flow in the conduit, and a closed position preventing said flow, and for which the first portion butts against a seal,said seal being provided with an opening enabling the gas to flow through the conduit, the seal having an extension which projects into the opening to partially cover said opening.

2. The valve as claimed in claim 1, wherein the seal extends in a single plane.

3. The valve as claimed in claim 2, wherein the extension defines an edge projecting into the opening and extending in a direction forming an intersection with two contiguous edges of the opening.

4. The valve as claimed in claim 1, wherein the extension engages, when the shutter is in closed position, a flat contact with the first portion of the shutter.

5. The valve as claimed in claim 1, wherein the opening is rectangular, the extension being triangular and coming out of at least one edge of the seal surrounding said opening.

6. The valve as claimed in claim 5, wherein the extension is a right triangle and is joined to at least two edges of the seal surrounding the opening.

7. The valve as claimed in claim 1, wherein the extension and the seal form a single part.

8. The valve as claimed in claim 1, wherein some material has been removed from the first portion of the shutter in a zone of which the outline corresponds to the outline of the extension of the seal, such as to enable said extension to be placed in said zone when the shutter is in a closed position.

9. The valve as claimed in claim 1, wherein the seal has a prolongation designed to interact with the second portion of the shutter.

10. The valve as claimed in claim 9, wherein the prolongation of the seal includes a secondary opening.

11. The valve as claimed in claim 10, wherein the prolongation of the seal has a rib, and the secondary opening is formed in said rib.