GB2276691A

GB2276691A - A stable actuating linkage for a flap valve

Info

Publication number: GB2276691A
Application number: GB9406514A
Authority: GB
Inventors: Jean Louis Rene Dauvergne
Original assignee: Valeo Thermique Habitacle
Current assignee: Valeo Thermique Habitacle
Priority date: 1993-04-01
Filing date: 1994-03-31
Publication date: 1994-10-05
Anticipated expiration: 2014-03-31
Also published as: FR2703303B1; GB9406514D0; GB2276691B; FR2703303A1

Abstract

A pivoted actuating crank (1), which drives through a connecting rod (3) a lever (9) which is in fixed relationship to the flap valve being actuated, overruns the position in which it is aligned with the connecting rod, until it comes into engagement on a mechanical abutment element (16), thus stabilising the position of the valve when the latter is subjected to applied forces that tend to exert thrusts on the actuating crank through the connecting rod. The invention is applicable to heating, ventilating and air conditioning installations for the cabins of motor vehicles. <IMAGE>

Description

A STABLE ACTUATING LINKAGE FOR A FLAP VALVE This invention relates to actuating means for the actuation of a pivoting flap valve for an installation for heating and/or ventilating, or for air conditioning, the cabin of a motor vehicle, in which the actuating means is a linkage comprising an actuating crank which is pivotable between a first extreme position and a second extreme position, and which is coupled through a connecting rod to a lever which is fixed with respect to the flap valve for rotation with the latter, so as to define for the valve a first controlled position and a second controlled position which correspond to the said first and second extreme positions of the crank, respectively. In its second controlled position, the flap valve is exposed to air pressure conditions which tend to urge the valve towards its first controlled position.Such a linkage will be referred to herein as a linkage of the kind specified.

Such a linkage is used in particular for the control of flap valves which are adapted to regulate the admission of recirculated and/or fresh air, under the direct control of the user, into air treatment means of the installation. When such a valve is in a position in which it blocks a stream of fresh air from outside the vehicle, variations in the running speed of the vehicle cause variations to occur in the dynamic pressure of this fresh air, and these variations tend to upset the stability of the valve in this position. By contrast with cam mechanisms, which do however have other disadvantages in that they call for forces to be applied and are particularly prone to heavy wear, the type of linkage which has a connecting rod does not in itself enable such stability as discussed above to be obtained.

An object of the invention is to improve such a connecting rod mechanism in such a way as to ensure that the flap valve will be stable in its said second controlled position.

According to the invention, in a linkage of the kind specified the crank passes through an intermediate position in which its pivot axis on which it is articulated to the connecting rod is interposed, in a common plane, between the pivot axis of the crank and the pivot axis on which the lever is articulated to the connecting rod, with an abutment element being provided for engagement by the crank in its said second extreme position.

According to a preferred feature of the invention, in the first extreme position of the crank, which is diametrically opposed to its said intermediate position, the pivot axis of the crank is interposed in a common plane between the two pivot axes of the connecting rod, with the first controlled position of the flap valve and that corresponding to the intermediate position of the crank constituting first and second extreme positions of the flap valve respectively.

Preferably, the second extreme position and the intermediate position of the crank are very close to each other, the second controlled position of the flap valve being substantially or very nearly coincident with the second extreme position.

Preferably, the second controlled position of the flap valve constitutes an intermediate position for the flap valve.

In its second extreme position, the crank is preferably biassed by a spring into engagement against the said abutment element.

Preferably, the said spring is a helical tension spring coupled between a fastening point which is fixed with respect to the crank and remote from the pivot axis of the crank, and a fixed point lying in opposition to the intermediate position of the crank with respect to the pivot axis of the latter.

The various features and advantages of the invention will appear more clearly on a reading of the description of preferred embodiments of the invention which follows, and which is given by way of example only and with reference to the accompanying drawings, in which: Figure 1 shows diagrammatically a valve actuating linkage in accordance with the current state of the art; Figure 2 is a view similar to Figure 1 showing a valve actuating linkage in a first embodiment of the invention; and Figure 3 is another view, similar to Figure 2 but showing a second embodiment of the linkage according to the invention.

The arrangement shown in Figure 1 comprises an actuating crank 1 which is arranged for pivoting movement about an axis 2 under the action of suitable driving means (not shown), which may for example be an electric motor driving the crank through a reducing gear, or a cable connected to a pull handle, or a slider actuated manually. The pivoting movement of the crank 1 is between two diametricaly opposed positions, namely a first extreme position indicated in full lines and a second extreme position indicated in broken lines. The crank 1 is articulated to a connecting rod 3, on a pivot axis indicated in Figure 1 at 4 for the first extreme position and 5 for the second extreme position.According to circumstances, the crank 1 is able to pivot in one direction to move from the first position to the second position, and in the opposite direction in order to go from the second position to the first position; or it may move always in the same direction, with its axis of articulation with the connecting rod 3 describing in the first case only one of the two semicircles 7 and 8 which have the end points 4 and 5, while in the second case it describes the whole circle.

The connecting rod 3 is also articulated, at its other end, to a lever 9, on a pivot axis passing through the point 10 in the first position and through the point 11 in the second position. The lever 9 is fixed with respect to a flap valve (not shown) of a heating or air conditioning installation for a motor vehicle. It drives this flap valve pivotally about an axis 12.

The points 4, 2, 5, 10 and 11 are aligned in that order along a line 13, the path of the flap valve pivot axis 12 being outside this line. The axis of the pivot between the connecting rod 3 and lever 9 follows a path in both its directions of movement, between the points 10 and 11, which consists of an arc of a circle 14, smaller than a semicircle and having a radius which is greater than that of the circle 7, 8. The chord of the arc 14 is equal to that of the semicircles 7 and 8, that is to say it is equal to the diameter of the circle 7, 8.

In current practice, in the first position shown in Figure 1 in full lines, the flap valve has no force applied to it, or forces are applied to it which tend to cause it to pivot away from the second position. In this last case, the lever 9 exerts a pushing force on the connecting rod 3, which is unable to become stabilised in the first position. On the other hand, in the second position a force exerted on the flap valve in the same direction as before, that is to say towards the first position, tend to displace the crank 1 away from its second position. The linkage is thus unstable.

Referring now to Figure 2, the same elements as in Figure 1 are indicated by the same reference numerals.

The crank 1 is driven in such a way that the axis of its pivot with the connecting rod 3 is displaced along the semicircular path 7 between the point 4 and the point 5, and slightly over-runs the point 5 so as to reach a point 15. It thus describes an angle greater than 180 degrees. At the end of its travel, the crank bears against a mechanical abutment element 16. In this second position, the points 2, 15 and 11 are not aligned with each other, and the force exerted by the connecting rod 3 on the crank 1 as a result of the forces exerted by the flap valve tend to reduce the obtuse angle which is defined by the crank 1 and the connecting rod 3, and therefore force the crank 1 against the abutment element 16. Its position is therefore now stable. This modification has a negligible effect on the position of the lever 9 and of the flap valve in space.

In the modified embodiment shown in Figure 3, the lever 9 is driven by the crank 1 through the connecting rod 3, in such a way as to be displaced between two extreme positions corresponding to the two extreme positions described above with reference to Figure 1, when the pivot axis between the crank 1 and connecting rod 3 describes the semicircle 7 between the points 4 and 5.

The crank 1 may also follow its course of travel in such a way that its pivot axis is displaced over part of the semicircle 8, i.e. from the point 5 to a point 17 which corresponds to a final position in which the crank 1 makes contact with the mechanical abutment element 16. In addition, a helical spring 18 is connected in tension between the pivot axis between the crank 1 and connecting rod 3 on the one hand, and a fixed point 19 on the other hand. This point 19 lies on the line 13 beyond the point 4. The action of this spring stabilises the intermediate position of the lever 9 and of the flap valve against the forces which are exerted in either direction. The spring 18 may be omitted if the flap valve is subject only to forces that tend to cause the lever 9 to pivot towards the point 10. Conversely, such a spring may be added if necessary to the arrangement shown in Figure 2.

The crank 1 may be arranged to engage the abutment element 16 not directly as described above, but through some other suitable element, for example the connecting rod 3.

Claims

1. An actuating linkage for a pivoting flap valve in an installation for heating and/or ventilating, or for air conditioning, the cabin of a motor vehicle, wherein the linkage comprises an actuating crank which is pivotable between a first extreme position and a second extreme position, the crank being coupled through a connecting rod to a lever which is fixed with respect to the flap valve for rotation with the latter, so as to define for the latter a first controlled position and a second controlled position which correspond respectively to the said first and second extreme positions, the flap valve being subjected in its second controlled position to air pressures which tend to bias it towards its first controlled position, and wherein the crank passes through an intermediate position in which its pivot axis on which it is articulated to the connecting rod is interposed, in a common plane, between the pivot axis of the crank and the pivot axis on which the lever is articulated to the connecting rod, with an abutment element being provided for engagement by the crank in its said second extreme position.

2. A linkage according to Claim 1, wherein in the first extreme position of the crank, which is diametrically opposed to its said intermediate position, the pivot axis of the crank is interposed in a common plane between the two pivot axes of the connecting rod, with the first controlled position of the flap valve and that corresponding to the intermediate position of the crank constituting first and second extreme positions of the flap valve respectively.

3. A linkage according to Claim 2, wherein the second extreme position and the intermediate position of the crank are very close to each other, the second controlled position of the flap valve being substantially coincident with the second extreme position.

4. A linkage according to Claim 2, wherein the second controlled position of the flap valve constitutes an intermediate position for the valve.

5. A linkage according to any one of the preceding Claims, wherein, in its second extreme position, the crank is biassed by a spring into engagement against the said abutment element.

6. A linkage according to Claim 5, wherein the said spring is a helical tension spring coupled between a fastening point which is fixed with respect to the crank and remote from the pivot axis of the crank, and a fixed point lying in opposition to the intermediate position of the crank with respect to the pivot axis of the latter.

7. An actuating linkage for a flap valve, substantially as described in the foregoing description with reference to Figure 2 or Figure 3 of the accompanying drawings.