FR3059737A1 - PNEUMATIC ACTUATOR FOR DISPLACING A THREE POSITIONS ELEMENT AND THERMAL MOTOR AIR CIRCUIT ASSEMBLY COMPRISING SAME - Google Patents

Abstract

The invention relates to a pneumatic actuator (10) for moving an element between three positions, the actuator comprising a housing (12) in which are housed at least: - a cup (20) mounted movably between a first and a third extreme positions (P1, P3) via a second intermediate position (P2), - a deformable membrane (22) carrying the cup (20) and delimiting a chamber (45) between the cup (20) and the housing (12), a duct (18) adapted to be connected to a vacuum source; a return means (50) for the cup (20); a ring gear (60) arranged between the cup (20) and the deformable membrane (22); ), the ring being configured to bear against the cup (20) in the first extreme position (P1) and having an annular flange (64) configured to bear on a stop (66) of the housing (12) defining the second intermediate position (P2).

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

059 737

62010

COURBEVOIE © IntCI ⁸ : F15 B 11/12 (2017.01)

PATENT INVENTION APPLICATION

A1

©) Date of filing: 06.12.16. © Applicant (s): VALEO CONTROL SYSTEMS (© Priority: ENGINE Simplified joint-stock company - FR. @ Inventor (s): GERBOT MAXIME and RIBERA FRE- DERIC. (43) Date of public availability of the request: 08.06.18 Bulletin 18/23. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): VALEO CONTROL SYSTEMS related: ENGINE Simplified joint-stock company. ©) Extension request (s): © Agent (s): VALEO CONTROL SYSTEMS ENGINE Simplified joint-stock company.

PNEUMATIC ACTUATOR FOR MOVING AN ELEMENT BETWEEN THREE POSITIONS AND AN ASSEMBLY FOR A HEAT ENGINE AIR CIRCUIT COMPRISING THE SAME.

FR 3 059 737 - A1 (£ /) The invention relates to a pneumatic actuator (10) for moving an element between three positions, the actuator comprising a housing (12) in which are housed at least:

- a cup (20) mounted to move between a first and a third extreme position (P1, P3) via a second intermediate position (P2),

- a deformable membrane (22) carrying the cup (20) and delimiting a chamber (45) between the cup (20) and the housing (12),

- a conduit (18) suitable for being connected to a source of vacuum,

- a return means (50) of the cup (20),

- a crown (60) arranged between the cup (20) and the deformable membrane (22), the crown being configured to bear against the cup (20) in the first extreme position (P1) and having an annular rim (64 ) configured to bear on a stop (66) of the housing (12) defining the second intermediate position (P2).

Pneumatic actuator for moving an element between three positions and an assembly for a heat engine air circuit comprising it

The present invention relates to a pneumatic actuator for moving an element between three positions and an assembly for a heat engine air circuit comprising it.

The invention applies in particular, but not exclusively, in the automotive field, the heat engine then making it possible to propel the vehicle.

The assembly comprises a first pipe and a second pipe forming a bypass of a portion of the first pipe, the first and second pipes being able to be traversed by a fluid. The assembly also includes a fluid routing system making it possible to vary the distribution of the fluid between the portion of the first pipe and the second pipe.

It is known to provide the referral system with an actuator making it possible to vary the distribution of the fluid between the portion of the first pipe and the second pipe.

Pneumatic actuators are known which are capable of moving an element between two extreme positions. A pneumatic actuator of this type generally comprises a housing in which are housed a cup, a deformable membrane and a return means. The cup is connected to the element to be moved and mounted mobile between two extreme positions. The deformable membrane carries the cup and is fixed at its periphery to the housing so as to delimit a chamber between the cup and an internal wall of the housing. The return means is configured to return the cup to one of the extreme positions. The application of a vacuum in the chamber ensures the displacement of the cup between the two positions.

However, such pneumatic actuators do not allow the flap to be positioned precisely in an intermediate position between the two extreme positions since the movement of the flap between the two extreme positions is proportional to the vacuum applied.

The invention aims to remedy this drawback by proposing a pneumatic actuator capable of moving an element between three stable positions while ensuring a limited space requirement and relatively easy assembly and mounting of the device without increasing the manufacturing cost of pneumatique pneumatic actuator.

To this end, the subject of the present invention is a pneumatic actuator for moving an element between three positions, an actuator comprising a housing in which are housed at least:

a cup connected to the element to be moved movably mounted between a first and a third extreme position via a second intermediate position, a deformable membrane carrying the cup and fixed at its periphery on the housing and delimiting a chamber between the cup and an internal wall upper part of the housing, a duct suitable for being connected to a source of vacuum and opening into the housing in order to apply a vacuum in the chamber, a return means arranged and configured to bring the cup back to the first extreme position, a crown arranged between the cup and the deformable membrane, the crown being configured to bear against a shoulder of the cup in the first extreme position and having an annular rim oriented towards the outside and configured to come to bear on a stop of the housing defining the second intermediate position.

Advantageously, such a pneumatic actuator according to the invention allows the displacement of an element between three stable positions while having a reduced size and cost of manufacture and a relatively easy assembly.

Indeed, the intermediate position is defined in a perfectly reliable manner by the support of an annular rim of the crown on a stop of the housing until the separation of the crown and the cup.

Thus, the intermediate position is fixed over a range of significant depression values thanks to the decoupling of the crown and the assembly formed by the cup and the rod.

ETn such a pneumatic actuator according to the invention then makes it possible to be able to produce a mixture of fluids coming from two separate circulation conduits or else to provide directing a fluid towards three circulation paths instead of two with traditional actuators with two stable positions.

The pneumatic actuator according to the invention can also include one or more of the characteristics below, considered individually or according to all technically possible combinations:

The support between the annular rim of the crown and the stop of the housing defining the second intermediate position is waterproof;

the central part of the membrane is crossed by a rod extending axially from one face of the cup facing a lower internal wall of the housing, the rod being connected to the element to be moved;

the cup is configured to abut on the upper internal wall of the housing defining the third extreme position.

the deformable membrane has a central part fixed to the rod the element by means of clipping;

the deformable membrane extends directly over at least a central portion of the cup;

the deformable membrane is made of elastomeric material; the deformable membrane is made of silicone;

the membrane comprises a set of woven fibers, the fiber fabric being covered with an elastomeric material;

the return means is a spring interposed between the cup and the upper internal wall of the housing;

the conduit suitable for being connected to a vacuum source opens into the upper internal wall of the housing in the axis of the spring; the housing and / or the cup and / or the crown is made of plastic or metal, the housing is formed by a lower capsule and an upper capsule assembled together;

the housing is formed by a lower capsule and an upper capsule assembled to each other in a leaktight manner;

the cup is configured to move from the first extreme position to the second intermediate position when the vacuum applied by the conduit in the sealed chamber is greater than a first predefined threshold;

the first predefined threshold is substantially between 200 and 350 mBars. the cup is configured to move from the second intermediate position to the third extreme position when the vacuum applied by the conduit in the sealed chamber is greater than a second predefined threshold;

the second predefined threshold is substantially between 450 and 600 mBars;

the actuator is configured so that the element is in the second intermediate position when the vacuum through the conduit in the chamber is within a predetermined range of values and between the first and second thresholds;

the predetermined range of depression values defining the second intermediate position has a width of at least 150 mBars; the crown remains in abutment on the stop of the housing during the displacement of the cup from the second intermediate position to the third extreme position;

the support of the crown on the housing stop during the displacement of the cup from the second intermediate position to the third extreme position is waterproof;

the variation in the position of the cup is proportional to the variation in the vacuum in the chamber during a first phase during which the cup moves from the first position to the second position;

the variation of the position of the cup is proportional to the variation of the vacuum in the chamber during a second phase during which the cup moves from the second position to the third position, the coefficients of proportionality respectively relating to the first and second phases being different from each other;

the proportionality coefficient of the second phase is lower than the proportionality coefficient of the first phase.

The invention also relates to an assembly for a heat engine air circuit, comprising:

a first pipe capable of conveying fluid, a second pipe extending between an inlet in the first pipe and an outlet in the first pipe, so as to form a bypass of a portion of the first pipe, a referral system fluid in one of the second pipe and of said portion of the first pipe, the referral system having:

• a first configuration allowing the fluid to flow mainly in said portion of the first pipe, • a second configuration allowing the fluid to flow mainly in the second pipe, and • a third configuration allowing the fluid to flow in said portion of the first pipe and in the second pipe in a predetermined proportion, • a pneumatic actuator as described above, the pneumatic actuator being arranged and configured to move a means for closing the switching system between three positions so that when the means of shutter is respectively in the first, second and third position, the referral system is respectively in the first, second and third configuration.

Advantageously, such an arrangement makes it possible to circulate the fluid either mainly in the first pipe, or mainly in the second pipe, or thanks to the stable intermediate position of the pneumatic actuator according to the invention to be able to mix the fluid on the two pipes. according to a predetermined proportion.

The heat engine air circuit assembly according to the invention may also include one or more of the characteristics below, considered individually or in all technically possible combinations:

the first line comprises a heat exchanger arranged to cool the air;

the closure means comprises a pivoting flap disposed at the entrance to the second pipe.

Other characteristics and advantages of the invention will appear on reading the detailed description of the embodiments given by way of nonlimiting and illustrated examples, accompanied by the figures below:

Figures 1, 2 and 3 are views in longitudinal section of an embodiment of a pneumatic actuator according to the invention, representing this actuator respectively in the first, second and third stable positions of the cup of the actuator, FIG. 4 represents a diagram illustrating the displacement of the cup of the pneumatic actuator of FIGS. 1 to 3 as a function of the vacuum exerted in the housing of the actuator, and FIG. 5 schematically represents an example of assembly for a heat engine air circuit according to the invention comprising a pneumatic actuator according to the invention.

In the various figures, similar elements are designated by identical references. In addition, the different elements are not necessarily shown to scale in order to present a view making it easier to understand the invention.

Referring to Figures 1 to 3 illustrating an embodiment of a pneumatic actuator 10 according to the invention, this actuator is configured to move an element (not illustrated in the figures) between three positions. Figures 1 and 3 respectively illustrate the first and third extreme positions while Figure 2 relates to the second intermediate position between the first and third extreme positions.

The pneumatic actuator 10 comprises a housing 12 preferably formed from a first capsule or lower capsule 14 and from a second capsule or upper capsule 16 assembled together. The assembly between the two capsules can be carried out in a sealed manner. For example, the lower 14 and upper 16 capsules are assembled to one another by clipping, or elastic snap-fastening, or welding, or crimping.

Preferably, the housing is made of plastic or metal.

In addition, the pneumatic actuator 10 comprises a conduit 18 suitable for being connected to a vacuum source, not shown, and opening into the housing 12 in order to apply a vacuum inside the housing 12. For example, the source vacuum pump.

In addition, the pneumatic actuator 10 comprises a cup 20 and a deformable membrane 22 housed in the housing 12.

The cup 20 is connected to the element to be moved and mounted mobile between a first extreme position P1, illustrated in FIG. 1, and a third extreme position P3, illustrated in FIG. 3, via a second intermediate position P2, illustrated in the figure 2.

The cup 20 is preferably substantially cylindrical or slightly frustoconical. It has a bottom 24 having a face 26 facing a lower internal wall 28 of the housing 12. The cup has a rod 30 extending axially from the face 26 of the bottom 24 of the cup 24. The rod 30 is configured to be connected to the element to be moved.

To this end, the lower capsule 14 of the housing has an annular rim defining an orifice 31 through which the rod 30 connecting with the element to be moved passes.

The cup 20 comprises a first tubular portion 32 and a second tubular portion 34 extending axially in the direction opposite to the rod. Thus, the first tubular portion 32 extends from a face 36 facing an upper internal wall 38 of the housing 12.

The second tubular portion 34 has a second diameter D2 greater than the first diameter D1 of the first tubular portion 32 of the cup 20.

In addition, the cup 20 has a shoulder 40 between the first tubular portion 32 and the second tubular portion 34. The shoulder 40 having a diameter between the second diameter D2 of the second tubular portion 34 and the first diameter DI of the first tubular portion 32.

In addition, the cup 20 is configured to come into abutment on the upper internal wall 38 of the housing 12 defining the third extreme position P3, in particular via a free end 41 of the second tubular portion 34 of the cup.

Preferably, the cup is made of plastic or metal.

The deformable membrane 22 is flexible and fixed at its periphery 42 on the housing 12. The periphery 42 of the deformable membrane 22 is clamped between a flange 44 of the upper capsule 16 and a flange 46 of the lower capsule 14 of the housing.

The deformable membrane 22 is made of elastomeric material. Preferably, the deformable membrane 22 is made of silicone. The membrane may also include a set of woven fibers, the fiber fabric being covered with an elastomeric material.

The deformable membrane 22 is arranged so that the cup 20 is between the deformable membrane 22 and the upper internal wall 38 of the housing. Thus, the deformable membrane is arranged so as to delimit a chamber 45 between the cup 20 and the upper internal wall 38 of the housing 12. The chamber 45 is sufficiently tight so that a vacuum exists when the vacuum pump is in operation. The variations in the depression in the chamber 45 allow the membrane and the elements which are linked to it to be displaced.

The deformable membrane 22 has a central part 48 crossed by the rod connected to the element to be moved. Preferably, the central part 48 is crossed in sealing by the rod. In other words, the central part 48 provides a seal on the rod. However, residual leaks are acceptable. Indeed, the action of the vacuum pump makes it possible to control the vacuum in chamber 45 even in the event of a residual leak.

The deformable membrane 22 extends directly over at least a central portion of the bottom 24 of the cup 20 and over the shoulder 40 of the cup.

In addition, E pneumatic actuator 10 comprises a return means 50 and a crown 60 housed in the housing 12.

The return means 50 is arranged and configured to bring the cup 20 back into the first extreme position P1.

Advantageously, the return means 50 is a spring 52 interposed between the cup 20 and the upper internal wall 38 of the housing 12. Preferably, the return means 50 is housed E inside the first tubular portion 32 in order to minimize the dimensions of E pneumatic actuator 10.

During the assembly of the pneumatic actuator 10, the return means 50 is prestressed between the upper internal wall 38 of the housing 12 and the upper face 36 of the bottom 24 of the cup 20. The return means 50 is thus configured to constantly stress the cup 20 so that it constantly deviates from the upper internal wall 38 of the housing 12.

Advantageously, the conduit suitable for being connected to a source of vacuum opens into the upper internal wall of the housing in the axis of the spring in order to minimize the dimensions of the pneumatic actuator 10.

The crown 60 is arranged between the cup 20 and the deformable membrane 22.

It is configured to bear against the shoulder 40 of the cup 20 in the first extreme position P1. It is further configured to bear against this shoulder 40 also in the second intermediate position P2 and in all the positions while the cup moves from the first extreme position P1 to the second intermediate position P2. For this purpose, the crown 60 has a first annular rim 62 oriented towards E inside forming a first circle whose diameter is substantially equal to the diameter of the shoulder 40. The first annular rim 62 and the cup 20 are thus configured so that the first annular rim 62 drives the cup 20 from the first extreme position P1 to the second intermediate position P2 while supporting the second tubular portion 34 of the cup 20.

In addition, the crown 60 has a second annular rim 64 oriented towards the outside E and configured to come to bear on an abutment 66 of the housing defining the second intermediate position P2. The stop 66 is formed by a shoulder 68 of the upper capsule 16 of the case. The support of the second annular rim 64 on the stop 66 can be waterproof.

In addition, pneumatique pneumatic actuator 10 is configured so that the second annular rim 64 of the crown 60 remains in abutment on the stop 66 of the housing during the displacement of the cup from the second intermediate position P2 to the third extreme position P3.

In cases where the support of the second annular rim 64 on the stop 66 is not leaktight, the vacuum generated by the vacuum pump ensures identical pressure on each side of the annular rim 64.

Preferably, the crown is made of plastic or metal.

With reference to FIG. 4 representing a diagram illustrating the displacement of the cup 20 of the pneumatic actuator 10 as a function of the vacuum applied in the housing 12, the actuator according to the invention and in particular the relative dimensions of the crown relative to to those of the cup as well as the stiffness constant of the return means are configured so that the cup moves from the first extreme position PI to the second intermediate position P2 when the vacuum applied by the conduit 18 in the chamber 45 is greater than a first predefined threshold Sl. For example, the first predefined threshold SI is substantially between 200 and 350 mBars.

In addition, the cup 20 is configured to move from the second intermediate position P2 to the third extreme position P3 when the vacuum applied by the conduit 18 in the chamber 45 is greater than a second predefined threshold S2. For example, the second predefined threshold S2 is substantially between 450 and 600 mBars.

In addition, pneumatic actuator 10 is configured so that the element is in the second intermediate position, relative to the second intermediate position P2 of the cup, when the vacuum applied by the conduit 18 in the chamber 45 is within a predetermined range. of values and between the first and second thresholds S1 and S2.

Preferably, the predetermined range of depression values defining the second intermediate position P2 of the cup has a width of at least 150 mBars.

In addition, the variation in the position of the cup is proportional to the variation in the vacuum in the chamber during a first phase during which the cup moves from the first position to the second position.

Likewise, the variation in the position of the cup is proportional to the variation in the vacuum in the chamber during a second phase during which the cup moves from the second position to the third position.

The proportionality coefficients relative to the first and second phases respectively are different from each other.

Preferably, the proportionality coefficient of the second phase is lower than the proportionality coefficient of the first phase.

The operation of the pneumatic actuator according to the embodiment described above will now be detailed.

The position shown in Figure 1 corresponds to the first extreme position Pl of the cup 20 corresponding to a first extreme position of the element to be moved. This position is reached when the duct 18 is connected to the open air or when the vacuum applied in the chamber 45 is below the threshold SI. A vacuum pump makes it possible to extract the air contained in the chamber or internal space of the housing defined between the membrane 22 and the upper internal wall 38 of the housing, thus generating a vacuum in the chamber 45.

With reference to FIG. 1, in this first extreme position P1, the cup 20 is pushed towards the lower internal wall 28 of the housing 12 by the return means 50 prestressed during assembly. The bottom 24 of the cup is in abutment via the central part 48 of the deformable membrane 22 against the lower internal wall 28 of the housing 12. The first annular rim 62 of the crown 60 is in abutment against the second tubular portion 34 and in abutment against the shoulder 40 of the cup 20 thanks to the joint action of the deformable membrane 22 and the return means 50.

The cup 20 remains in this first extreme position PI as long as the vacuum applied in the chamber is less than the first predefined threshold S1.

During the first phase, the cup moves from the first extreme position PI to the second intermediate position P2 in proportion to the vacuum applied in the chamber 45.

During this first phase, the return spring 52 compresses under the action of the displacement of the cup 20.

Simultaneously, the deformable membrane 22 deforms and displaces the assembly formed by the cup 20 and the crown 60 towards the lower internal wall 28 of the housing 12 until the crown 60 abuts on the housing 12 via its second annular rim 64, defining the second intermediate position P2.

The second intermediate position P2 of the cup illustrated in FIG. 2 is a stable position which is perfectly defined due to the support of the second annular rim 64 of the crown 60 on the housing 12 allowing the surface to be varied instantly and significantly of the movable part of the deformable membrane on which the vacuum is applied.

Thus, the cup remains in this second intermediate position P2 as long as the vacuum applied by the conduit 18 in the chamber 45 is included in a predetermined range of width values at least equal to 150 mBars and less than the second predefined threshold S2.

As soon as the vacuum is greater than the second predefined threshold S2, the cup 20 moves from the second intermediate position P2 to the third extreme position P3 in proportion to the vacuum applied in the chamber 45.

During this second phase, the return spring 52 compresses more under the action of the displacement of the cup 20.

Simultaneously, the deformable membrane 22 deforms and only displaces the cup 20 in displacement in the direction of the lower internal wall 28 of the housing 12. The crown 60 remains in abutment on the housing 12 via its second annular rim 64.

Referring to Figure 3, the cup 20 moves as the depression in the chamber increases, until it abuts on the upper internal wall 38 of the housing 12. It is then in the third extreme position P3 which is also perfectly defined due to the stop of the free end 41 of the second tubular portion 34 of the cup on the housing.

Of course, the gradual decrease in depression allows the cup to return to the first extreme position PI reversibly.

Such a pneumatic actuator according to the invention has a certain number of advantages, in particular by allowing the displacement of an element between three stable positions while having a reduced bulk and a relatively easy assembly.

It finds a perfectly advantageous application in the automotive field, and in particular assemblies for a heat engine air circuit then making it possible to propel the vehicle.

Another object of the invention relates to an assembly for a heat engine air circuit. Figure 5 illustrates an example of such an assembly. This is for example a vehicle type diesel engine or spark ignition. The assembly 100 is in the example part of the intake circuit of the heat engine. It is for example arranged downstream of the outlet in the intake circuit of an exhaust gas recirculation loop.

The assembly 100 can also be associated with a supercharging compressor not shown in the figures.

The assembly 100 includes a first pipe 102 capable of conveying fluid and a second pipe 104 extending between an inlet 106 in the first pipe 102 and an outlet 108 in the first pipe.

As shown in FIG. 1, the second pipe 104 thus forms a bypass of a portion 110 of the first pipe 102. Conversely, the portion 110 of the first pipe makes it possible to bypass, “bypass” in English, the second pipe 104.

The assembly 100 further comprises a system 112 for routing the fluid in one of the second pipe 104 and of said portion 110 of the first pipe 102.

The fluid switching system 112 has three possible configurations.

In a first configuration, it allows the fluid to circulate mainly in the portion 110 of the first pipe 102. The term predominantly used above must be understood as meaning “more than half in flow rate of the fluid is directed in the portion 110 of the first pipe upstream of the inlet 106 of the second pipe 104 ".

In a second configuration, the fluid mainly flows in the second pipe 104, the first pipe 102 being crossed by the fluid only outside the portion 110. Thus, the fluid is diverted over a portion of the first pipe .

In a third configuration, the fluid flows both into the second pipe 104 and into the portion 110 of the first pipe 102 in a predetermined proportion.

To this end, the referral system comprises a pneumatic actuator according to the invention and as described above.

The pneumatic actuator is arranged and configured to move a shutter means 120 of the referral system 112 between three positions so that when the shutter means 120 are respectively in the first, second and third positions, the shutter system switch 112 is in the first, second and third configuration respectively.

In the example illustrated, the shutter means 120 comprises a pivoting flap disposed at the inlet 106 of the second pipe 104.

Advantageously, the first pipe 102 comprises a heat exchanger 122 arranged to cool the air. More specifically, the heat exchanger is arranged on the portion 110 of the first pipe 102.

Such an assembly for a heat engine air circuit can thus be used to recirculate to the intake part of the exhaust gases from an engine. In general, the use of exhaust gas recirculation on a spark-ignition engine makes it possible to reduce fuel consumption, which makes it a very attractive technology, particularly when it is applied to a supercharged engine. By supercharged means that the engine intake air is compressed by a supercharging device before being admitted to the engine. It is thus well known to those skilled in the art to carry out a recirculation of exhaust gases of the "low pressure" type, in which a part of the exhaust gases is returned to the intake circuit, upstream of the device. overeating. The proportion of recirculated gases is then controlled by such a referral system.

The invention has been described in the context of a control for moving a shutter in an exhaust gas recirculation circuit, however it could also be applied to controls for moving shutters in heating or air conditioning installations. of car.

Claims (10)

1. Pneumatic actuator (10) for moving an element between three positions, the actuator comprising a housing (12) in which are housed at least: a cup (20) connected to the element to be moved, movably mounted between a first and a third extreme position (PI, P3) via a second intermediate position (P2), a deformable membrane (22) carrying the cup (20) and fixed at its periphery (42) on the housing (12) and delimiting a chamber (45) between the cup (20) and an upper internal wall (38) of the housing (12), a conduit (18) suitable for being connected to a source of vacuum and opening into the housing (12) in order to apply a vacuum in the chamber (45), a return means (50) arranged and configured to bring the cup (20) back to the first extreme position (PI), a crown (60) arranged between the cup (20) and the deformable membrane (22), the crown being configured to bear against a shoulder (40) of the cup (20) in the first extreme position (PI) and having an annular rim (64) oriented towards the outside and configured to come into support on a stop (66) of the housing (12) defining the second intermediate position (P2). 2. Pneumatic actuator according to claim 1, in which the central part (48) of the membrane (22) is traversed by a rod (30) extending axially from a face (26) of the cup (20) facing a lower internal wall (28) of the housing (12), the rod (30) being connected to the element to be moved. 3. Pneumatic actuator according to claim 1 or 2, wherein the cup (20) is configured to abut on the upper internal wall (38) of the housing defining the third extreme position (P3). 4. Pneumatic actuator according to any one of claims 1 to 3, in which the cup (20) is configured to move from the first extreme position (Pl) to the second intermediate position (P2) when the vacuum applied by the conduit (18) in the sealed chamber (45) is greater than a first predefined threshold (SI). 5. Pneumatic actuator according to any one of claims 1 to 4, in which the cup (20) is configured to move from the second intermediate position (P2) to the third extreme position (P3) when the vacuum applied by the conduit (18) in the sealed chamber (45) is greater than a second predefined threshold (S2). 6. Pneumatic actuator according to claim 5 when dependent on claim 4, wherein the actuator (10) is configured so that the element is in the second intermediate position when the vacuum through the conduit in the chamber is included within a predetermined range of values and between the first and second thresholds. 7. Pneumatic actuator according to any one of claims 1 to 6, in which the crown (60) remains in abutment on the stop (66) of the housing (12) during the displacement of the cup (20) from the second intermediate position (P2) towards the third extreme position (P3). 8. Pneumatic actuator according to any one of claims 1 to 7, in which: the variation of the position of the cup (20) is proportional to the variation of the vacuum in the chamber (45) during a first phase during which the cup (20) moves from the first position (Pl) to the second position (P2); the variation of the position of the cup (20) is proportional to the variation of the depression in the chamber (45) during a second phase during which the cup (20) moves from the second position (P2) towards the third position (P3); and the proportionality coefficients relative to the first and second phases respectively being different from each other. 9. Set (100) for heat engine air circuit, comprising: a first pipe (102) capable of conveying fluid, a second pipe (104) extending between an inlet (106) in the first pipe (102) and an outlet (108) in the first pipe (102), so forming a bypass of a portion (110) of the first pipe (102), a system for directing (112) the fluid in one of the second pipe (104) and of said portion (110) of the first line (102), the referral system (112) having: • a first configuration allowing the fluid to flow mainly in said portion (110) of the first pipe (102), • a second configuration allowing the fluid to flow mainly in the second pipe (102), and • a third configuration allowing the fluid to circulate in said portion (110) of the first pipe (102) and in the second pipe (102) in a predetermined proportion, • a pneumatic actuator according to any one of the preceding claims, the pneumatic actuator being arranged and configured for moving a shutter means (120) of the referral system between three positions so that when the shutter means is respectively in the first, second and third positions, the referral system is respectively in the first, second and third configuration. 10. The assembly of claim 9, wherein the first pipe (102) comprises a heat exchanger (122) arranged to cool the air. 2/4