ELECTRICALLY CONTROLLED VALVE FOR HOT FLUID

Abstract

An electrically controlled valve for the circulation of hot fluids is made up of an electromagnetic actuator and a valve. The valve has an opening provided with a movable sealing member driven by a rotation shaft perpendicular to the axis of the opening, the electromagnetic actuator driving the rotation of the shaft, the output shaft of the actuator being substantially coaxial with the rotation shaft. The front end of the rotation shaft and the front end of the output shaft are not in direct contact. The coupling between the rotation shaft of the valve and the output shaft of the actuator is provided by a coupling member placed between the front end of the output shaft and the front end of the shaft. The coupling member transmitting rotation torque with a misalignment tolerance between the output shaft and the rotation shaft of the valve. The valve also having thermally insulation for mechanical connection between peripheral areas of the body of the actuator and the body of the valve.

Claims

1. An electrically-controlled valve for circulating hot fluids, the electrically-controlled valve comprising: an electromagnetic actuator; a valve having an orifice provided with a movable blanking member driven by a rotation shaft at right angles to an axis of the orifice; the electromagnetic actuator driving rotation of the shaft, an output axis of the actuator being substantially coaxial with the rotation shaft; a front end of the rotation shaft and a front end of the output axis not being in direct contact; a coupling between the rotation shaft of the valve and the output axis of the actuator is ensured by a coupling member placed between the front end of the output axis and the front end of the shaft; the coupling member having a rotation torque transmission with a misalignment tolerance between the output shaft on the one hand and the rotation shaft of the valve on the other hand; a thermally insulating mechanical link between peripheral areas of a body of the actuator and the body of the valve; and the coupling member comprising a first part fixed to the end of one of the shafts, engaged in a transverse groove formed in a complementary second part fixed to the end of an other of the shafts, the second part having a solid cross section.

2. The electrically-controlled valve as claimed in claim 1, wherein at least one of the first part and the second part are of a thermally insulating material and the second part has a section inscribed in a diameter at least two times greater than that of the rotation shaft.

3. The electrically-controlled valve as claimed in claim 2, wherein the second part has a circular outer form.

4. The electrically-controlled valve as claimed in claim 1, wherein the coupling member is at least partly a material of low thermal conductivity.

5. The electrically-controlled valve as claimed in claim 1, further comprising at least one steel plate between a front surface of the valve and a front surface of the actuator.

6. The electrically-controlled valve as claimed in claim 5, wherein the at least one steel plate is at least two steel plates separated by an insulating blade, between the front surface of the valve and the front surface of the actuator.

7. The electrically-controlled valve as claimed in claim 1, wherein the coupling member is partly stainless steel.

8. The electrically-controlled valve as claimed in claim 1, wherein the coupling member is at least partly ceramic.

9. The electrically-controlled valve as claimed in claim 1, wherein the coupling member is an Oldham joint.

10. The electrically-controlled valve as claimed in claim 1, wherein the actuator has at least three peripheral link areas for fixing onto the valve.

11. The electrically-controlled valve as claimed in claim 1, wherein the said coupling member has a discal surface of deflection directed toward the front surface of the valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be better understood on reading the following description relating to a nonlimiting exemplary embodiment of a circulation valve according to the invention, referring to the attached drawings in which:

[0023] FIG. 1 represents a cross-sectional view of a first exemplary embodiment;

[0024] FIG. 2 represents a perspective view of the first exemplary embodiment;

[0025] FIG. 3 represents a cross-sectional view of a second exemplary embodiment;

[0026] FIG. 4 represents a perspective view of a third exemplary embodiment; and

[0027] FIG. 5 represents an isolated view of the coupling member with the blanking member.

DETAILED DESCRIPTION

[0028] The valve described with reference to FIGS. 1 and 2 comprises, as is known, an electromagnetic actuator (1) ensuring the angle of displacement of a metal shaft (2). In the example described, reprising an exemplary embodiment of an exhaust gas recirculation valve, the actuator (1) comprises a metal front body (3), for example made by aluminum casting or of an alloy ensuring a good thermal conduction. This front body (3) has cavities (4) for the circulation of a heat transfer fluid making it possible to ensure the cooling of the actuator.

[0029] The valve (5) comprises a metal valve body (6) defining an orifice (7) which can be blanked by a blanking member (8). This blanking member (8) is controlled in rotation by a drive shaft (26). This shaft (26) is guided by a front bearing (27) and a sealed rear bearing (28).

[0030] The mechanical link between the actuator (1) and the valve (5) is ensured by three screws (9, 10 and 11) engaging in threaded tappings (12 to 14) provided on the front body (3) of the actuator (1). The front surface (15) of the body of the actuator (1) has three annular protuberances (16 to 18) surrounding the mouth of the threaded tappings (12 to 14). These annular protuberances (12 to 14) make it possible to reduce the contact surfaces between the body (3) of the actuator (1) and the body of the valve (5) and therefore to reduce the thermal conduction.

[0031] To further reduce the thermal conduction between the body of the valve (5) and the body of the actuator (1), thermal insulation washers (19 to 21) are interposed between said annular protuberances (12 to 14) and the body of the valve (5). Similarly, thermal insulation washers (22 to 24) are interposed between the body of the valve (5) and the heads of the screws (9 to 11). These insulating washers are for example ceramic or epoxy glass or Bakelite washers, or even washers made of any other material of low thermal conductivity.

[0032] The rear part of the body (6) of the valve (5) has a cylindrical cavity (25) in which is housed a system (41) for coupling the shaft (2) of the actuator with the rotation shaft (26) of the blanking member (8) of the valve. The shaft (2) of the actuator and the shaft (26) of the blanking member are aligned and coaxial. Their front ends are offset longitudinally to reserve an air gap limiting the thermal conduction between the two shafts (2, 26).

[0033] The coupling between the ends of the two shafts (2, 26) is ensured by the cooperation between a first part (29) fixed to the end of one of said shafts (2), engaged in a diametral groove formed in a complementary second part (30) fixed to the end of the other of said shafts. The first part (29) and/or the second part (30) are produced in a thermally insulating material. The second part (30) has a cup form whose bottom has a cross section inscribed in a diameter at least two times greater, and typically three times greater, than the diameter of the rotation shaft of the valve (26). The second part has a transverse groove to allow the coupling of the first part (29).

[0034] The bottom of the second part (30) makes it possible to form a screen to the rise of hot gases toward the actuator. The cup form makes it possible to confer a compactness on the valve while limiting the transfer of hot gases and ensuring a good mechanical link. The coupling can also be produced by an Oldham joint, used in an unusual way for two axes that are virtually aligned and not greatly offset. This coupling method providing a part engaged in a complementary groove makes it possible to absorb low axial offsets between the two shafts (2, 26) and above all thermally insulate the two shafts.

[0035] FIG. 3 represents a variant embodiment that is distinguished by the presence of a plate (31) formed by a thin steel plate placed between the valve (5) and the actuator (1). The front body (3) of the actuator (1) has cylindrical columns (32 to 34) passed through by screws (35 to 37) ensuring the link with the body (6) of the valve. Thermally insulating spacers (38 to 40) are interposed between the end of the columns (32 to 34) and the steel plate (31).

[0036] The steel plate (31) is made up of two metal sheets separated by an air blade. It reflects the thermal radiation emitted by the valve (5). It is pierced with a hole for the passage of the shaft (2) of the actuator. It can be slightly dished to form a concave thermal shield, seen from the side of the valve (5).

[0037] In this exemplary embodiment, the actuator (1) comprises: [0038] a metal lower body (3), with a cooling circuit emerging from an end fitting (42), and [0039] an upper body (43) in a material of low thermal conductivity, for example a plastic material.
This upper body of low thermal conductivity makes it possible to limit the residual thermal transmission between the shaft (2) and the actuator, and in particular the electronic circuit with which the actuator is equipped.

[0040] FIG. 4 presents another embodiment specifically dedicated to a discharge valve of a main duct (44), also commonly called “waste gate”. It also includes the constituent elements of the invention with, in particular, the actuator (1) which displaces a blanking member (8) in rotation, regulating the opening of the valve (5) serving as duct for diverting hot fluid from the main duct (44).