The invention relates to a valve flap sub-assembly, especially of a vehicle's air conditioning unit.

Air conditioning units for vehicles serve for the air conditioning of the vehicle's interior. They can be designed as heating units, ventilation units or air conditioning systems.

Customarily, a plurality of air ducts branch off from air conditioning units of vehicles and lead into the vehicle's interior at various points. A valve flap is usually arranged in each of the air ducts and can increase or decrease the flow cross section of the air duct right up to the complete closing off of the air duct .

For optimum air conditioning of the vehicle's interior, it is necessary that the valve flaps can be opened or closed independently of each other. At the same time, it is also desirable, however, that all the valve flaps are able to be driven by only one actuating element, for example by an electric motor, for cost reasons.

In order to be able to meet these two requirements, it is known to interconnect the valve flaps by means of a gearing. Also known are solutions in which individual valve flaps are arranged on offset sections of the shaft which drives the valve flaps in order to be able to realize different angular speeds by means of an individual shaft. However, these approaches are very complex and require a larger installation space which as a rule is extremely limited in vehicle construction.

It is the object of the invention to provide a valve flap sub-assembly which in a simple and space-saving manner enables the individual valve flaps of the sub- assembly to be able to be adjusted independently of each other.

The object is achieved by means of a valve flap sub- assembly, especially of a vehicle's air conditioning unit, having a first valve flap which is arranged in a rotation-resistant manner on a first shaft, a second valve flap and a free-wheeling device which connects the first shaft to the second valve flap, wherein the first valve flap can be rotated by a free-wheeling angle in relation to the second valve flap from an initial position in an adjustment direction and the free-wheeling device drives the second valve flap in the case of rotational angles of the first valve flap being larger than the free-wheeling angle. The freewheeling device makes its possible for the rotational angle of the first valve flap to be able to be selected within the free-wheeling angle independently of the rotational angle of the second flap valve. In this way, controlling the air flows of the vehicle's air conditioning unit by means of only one actuator, but independently of each other, is possible. In this case, the intended rotational direction of the first valve flap from the initial position is understood by adjustment direction and the rotational angle is defined as the angle by which the corresponding component is rotated from its initial position in the adjustment direction. Naturally, all devices which can influence the room climate in the vehicle's interior, such as heating units, ventilation units or air conditioning systems, are to be understood by air conditioning units of vehicles .

The valve flap in the initial position preferably fully closes off an air duct associated with it so that the air duct can be opened separately from the other air ducts .

For example, the first shaft is operated by an actuator, especially by an electric motor, as a result of which a simple and inexpensive embodiment of the valve flap sub-assembly is made possible.

In an embodiment variant of the invention, the first shaft extends through the free-wheeling device so that the free-wheeling device can be provided at any position on the first shaft in order to ensure a greatest possible degree of flexibility of the construction .

The free-wheeling angle can lie between 2° and 40°, especially between 10° and 40°, as a result of which a sufficiently large independence of the first valve flap from the second valve flap is achieved.

In one embodiment of the invention, the valve flap sub ^¬ assembly has a second shaft to which the second valve flap is connected in a rotation-resistant manner, wherein the first shaft and the second shaft are arranged coaxially. As a result of the coaxial arrangement of the shafts, the installation space required for the valve flap sub-assembly is reduced.

The valve flap sub-assembly has, for example, a third valve flap which is connected in a rotation-resistant manner to the second shaft, as a result of which the first valve flap can also be rotated within the free ^¬ wheeling angle independently of the third valve flap. The valve flap sub-assembly can have a fourth valve flap which is connected in a rotation-resistant manner to the first shaft, as a result of which the fourth valve flap can be operated within the free-wheeling angle independently of the second and the third valve flaps .

In one embodiment of the invention, the second valve flap or the second and the third valve flaps are arranged between the first valve flap and the fourth valve flap, wherein the second valve flap and/or the second shaft are of hollow design and the first shaft extends through the second valve flap and/or through the second shaft. In this way, it is possible that valve flaps which do not lie next to each other can be rotated at the same time by the same rotational angle.

In an embodiment variant, a second free-wheeling device is provided between the fourth valve flap and the third valve flap so that the second shaft can be connected to the first shaft at a second point in order to improve the stability of the second shaft. In one embodiment of the invention, the free-wheeling device has an input part, which is connected in a rotation-resistant manner to the first shaft, and an output part which is connected in a rotation-resistant manner to the second valve flap and/or to the second shaft, wherein the input part at least partially accommodates the output part and the input part has at least one stop and the output part has at least one dog, wherein the at least one stop, after rotation of the input part by the free-wheeling angle in relation to the output part from the initial position in the adjustment direction, butts against the at least one dog. As a result, a free-wheeling device is realized in a simple way. The free-wheeling device preferably has a return element, especially a spring, especially preferably a spiral spring, which is supported on the input part and on the output part and which can act upon the output part with a torque against the adjustment direction, as a result of which it is ensured that the second air flap is located in its original position providing the rotational angle of the first valve flap lies between the initial position and the free-wheeling angle.

For example, in the initial position the return element is pretensioned and acts upon the output part with a torque against the adjustment direction so that the second valve flap closes off its air duct securely and tightly .

Further features and advantages of the invention are gathered from the following description and also from the attached drawings to which reference is made. In the drawings :

Figure 1 schematically shows a vehicle's air conditioning unit with a valve flap sub-assembly according to the invention in perspective view,

Figure 2 shows a valve flap sub-assembly according to the invention in an exploded view, - Figure 3 shows the valve flap sub-assembly according to Fig. 2 in section,

Figures 4a to 4c show a cross section along the line IV-IV from Figure 3, wherein the free wheeling device is shown in three different positions ,

Figures 5a to 5d schematically show the positions of the valve flaps of the valve flap sub-assembly according to the invention according to Fig. 3 in different positions, and Figure 6 shows a further embodiment of a valve flap sub-assembly according to the invention.

Shown schematically in Figure 1 is an air conditioning unit 4 of a vehicle. The vehicle's air conditioning unit 4 in the depicted embodiment has a first air duct 6 and a second air duct 8 which are in flow communication with the vehicle's interior (not shown). For example, the first air duct 6 leads in the direction of a side window of the vehicle, whereas the second air duct 8 leads from the centre console centrally into the vehicle's interior in the direction of the occupants of the vehicle.

The vehicle's air conditioning unit 4 has further air ducts, not shown for the sake of clarity, which for example lead directly beneath the windscreen. Provision is made on the vehicle's air conditioning unit 4 for a valve flap sub-assembly 10 which features a first valve flap 12 and a second valve flap 14 between which provision is made for a free-wheeling device 16.

The first valve flap 12 is rotatably arranged in the first air duct 6 and the second valve flap 14 is rotatably arranged in the second air duct 8. By rotation of the valve flaps 12, 14 the size of the flow cross section of the air ducts 6, 8 associated with them can be increased or decreased right up to complete closing off of the air ducts 6, 8. In Figure 2, the valve flap sub-assembly 10 is shown in exploded view and in Figure 3 is shown in cross section. The first valve flap 12 is arranged in a rotation-resistant manner on a first shaft 18, wherein the first shaft 18 is connected to the free-wheeling device 16.

The second valve flap 14 is arranged in a rotation- resistant manner on a second shaft 20 which is also in communication with the free-wheeling device 16.

The two shafts 18, 20 are arranged coaxially, that is to say in alignment.

It is also conceivable, however, that the first valve flap 12 and/or the second valve flap 14 are not, or is not, arranged on a shaft 18, 20 but are connected directly to the free-wheeling device 16.

The free-wheeling device 16 has an input part 22, an output part 24 and a return element 26.

As is evident in Figure 3, the input part 22 is connected in a rotation-resistant manner to the first valve flap 12 and therefore to the first shaft 18.

Correspondingly, the output part 24 is connected in a rotation-resistant manner to the second shaft 20.

On its side facing the second valve flap 14, the input part 22 has a circular cylindrical section 28 which is open towards the output part 24. On the inner circumference of the circular cylindrical section 28 provision is made for at least one stop 30 which extends radially inwards, as is shown in Figure 4a, for example. Extending into the circular cylindrical section 28 from the output part 24 is at least one dog 32 which is arranged in a manner offset from the stop 30 in the circumferential direction but is provided at the same radial distance from the centre axis of the circular cylindrical section 28.

The output part 24 is connected in turn in a rotation- resistant manner to the second valve flap 14 or to the second shaft 20.

Also provided inside the circular cylindrical section 28 is the return element 26 which is supported both on the input part 22 and on the output part 24.

The return element 26 is a spring or a spiral spring, for example. In the depicted embodiment, the return element 26 is a spiral spring which is provided radially between the two dogs 32 of the output part 24 and which encompasses a hollow, circular cylindrical extension 34 of the output part 24.

The return element 26 can create a torque upon the input part 22 or the output part 24 during rotation of the input part 22 in relation to the output part 24. The first shaft 18 extends through the entire free ^¬ wheeling device 16. In detail, the first shaft 18 extends through the circular cylindrical section 28 of the input part 22, through the circular cylindrical extension 34 of the output part 24 and then through the second shaft 20 or through the second valve flap 14. The second valve flap 14 and the second shaft 20 are of hollow design accordingly.

The first shaft 18 can be driven by an actuator 36, for example by an electric motor.

In Figures 4a to 4c, three different positions of the free-wheeling device 16 are shown. The position in Figure 4a corresponds to the initial position, as is also shown in Figure 3. In this position, the first valve flap 12 and the second valve flap 14 completely close off the first air duct 6 or the second air duct 8.

The valve flaps 12, 14 can be rotated from the initial position, for example anticlockwise with regard to the views in Figures 4a to 4c. This direction is identified as the adjustment direction V in the following text.

So that in the initial position it is ensured that the second valve flap 14 reliably closes off the second air duct 8, the return element 26 can be pretensioned so that the second valve flap 14 is acted upon by a closing torque against the adjustment direction V.

In the initial position, the dogs 32 of the output part 24 are at a distance from the stops 30 of the input part 22 in the circumferential direction by a free ^¬ wheeling angle a. The free-wheeling angle a can lie between 2° and 40°. By means of the actuator 36, the first shaft 18 and therefore the first valve flap 12 and the input part 22 can now be rotated in the adjustment direction V.

Providing the rotational angle - defined here as the angle by which the corresponding part has been rotated from its initial position in the adjustment direction V of the first shaft 18 is smaller than the free ^¬ wheeling angle a the input part 22 rotates relative to the output part 24 so that only the first valve flap 12 is rotated but not the second valve flap 14. Consequently, the first valve flap 12 can be rotated in relation to the second valve flap 14 by the free ^¬ wheeling angle a. In Figure 4b, the first shaft 18 and therefore the input part 22 has now been rotated from the initial position by the free-wheeling angle a, whereas the output part 24 is still located in its initial position .

The stop 30 of the input part 22 now butts against the dog 32 so that a further movement of the input part 22 would also lead to a movement of the output part 24.

The return element 26 in this position can be located in its neutral position. However, it preferably continues to remain in a tensioned state and acts upon the output part 24 with a closing force against the adjustment direction V.

If now by means of the actuator 36 the rotational angle of the first shaft 18 together with the first valve flap 12 and therefore the input part 22 is increased further, that is to say rotated further in the adjustment direction V from the initial position, then as a result of the form fit between the stop 30 and the dog 32 the output part 24 and therefore the second valve flap 14 are now driven together. Such a position is shown by way of example in Figure 4c.

The first shaft 18 together with the first valve flap 12 and the input part 22 can now be rotated further in the adjustment direction V until an end position is reached in which both the first valve flap 12 and the second valve flap 14 almost completely free the first air duct 6 or the second air duct 8. So that both the first valve flap 12 and the second valve flap 14 almost completely free their associated air ducts 6, 8 it is necessary to balance the advance which the first valve flap 12 has in relation to the second valve flap 14.

This can be realized for example by means of an additional free wheel between the first valve flap 12 and the first shaft 18 or free-wheeling device 16. If the first valve flap 12 reaches its end position, the first valve flap 12 is prevented from rotating further, for example by means of a stop. By means of the additional freewheel, however, the first shaft 18 and consequently the second valve flap 14 can be rotated further until the second valve flap 14 has also reached its end position. It is also conceivable that between the first valve flap 12 and the second valve flap 14 provision is made for a gearing which adjusts the angular speeds of the two valve flaps 12, 14 in relation to each other in such a way that the two valve flaps 12, 14 reach their end position at the same time.

For example, the simultaneous reaching of the end position of the two valve flaps 12, 14 can also be enabled by the maximum rotational angle of the second valve flap 14 being smaller by the free-wheeling angle a than the maximum rotational angle of the first valve flap 12. To this end, the initial position of the second valve flap 14 would have to lie between the initial position of the first valve flap 12 and the end position of the two valve flaps 12, 14, i.e. in the initial position the second valve flap 14 would already be arranged at steeper angle in the air duct 8 than the first valve flap 12 in its initial position in the air duct 6.

In Figures 5a to 5d the valve flaps 12, 14 are shown in the different positions. In this case, the left-hand view corresponds in each case to the position of the first valve flap 12 and the right-hand view corresponds to the position of the second valve flap 14.

Shown in Figure 5a is the position of the first valve flap 12 and of the second valve flap 14 in the initial position according to Figure 3a. In this position, the valve flaps 12 and 14 completely close off their respective air ducts 6 and 8. In the case described in relation to Figure 1, in which the first air duct 6 leads to a side window and the air duct 8 leads from the centre console in the direction of the occupants, the position of Figure 5a corresponds to a de-icing position of the windscreen since the air flow created by the vehicle's air conditioning unit cannot flow through the air ducts 6, 8 but has to flow through a further air duct, for example in the direction of the windscreen. The position of the valve flaps 12 and 14 shown in Figure 5b corresponds to a rotation of the first valve flap 12 by the free-wheeling angle a, as is shown in Figure 3b. In this position, the first valve flap 12 is rotated by the free-wheeling angle a and therefore opens the first air duct 6, for example to 20%. At the same time, however, the second air duct 8 remains completely closed off by the second valve flap 14.

In this way, the first air duct 6 or the first valve flap 12 can be opened independently of the second air duct 8 or of the second valve flap 14.

By means of this position, in the aforesaid example the side window can be effectively freed of condensed water or misting of the side window can be prevented.

In the third position shown in Figure 5c, the first valve flap 12 is rotated further from the initial position than the free-wheeling angle a. This corresponds to the position which is shown in Figure 3c. In this position, both the first air duct 6 and the second air duct 8 are partially open so that air from the vehicle's air conditioning unit 4 can flow through both air ducts 6, 8 into the vehicle's interior. For example, the first air duct is opened to 35% and the second air duct 8 is opened to 15%. This position corresponds to a heating position of the vehicle's air conditioning unit 4, in which warm air is fed directly to the vehicle's interior while at the same time misting of the side window is also prevented. The position shown in Figure 5d corresponds to the end position of the first valve flap 12 and of the second valve flap 14, in which both the first air duct 6 and the second air duct 8 are almost completely open, i.e. apart from the width of the valve flaps 12, 14 which minimally reduces the flow cross section.

This position is provided for example for the rapid cooling of the vehicle's interior. Shown perspectively in Figure 6 is a second embodiment of a valve flap sub-assembly 10. The valve flap sub ^¬ assembly according to Figure 6 corresponds to that according to Figure 2 so that in the following text only the differences are dealt with and the same or functionally the same parts are identified by the same designations .

The valve flap sub-assembly 10 according to Figure 6, in addition to the first valve flap 12 and the second valve flap 14 has a third valve flap 38 which is connected in a rotation-resistant manner to the second shaft 20. Naturally, the third valve flap 38 can also be connected directly to the second valve flap 14.

Arranged on the side of the third valve flap 38 facing away from the second valve flap 14 is a fourth valve flap 40 which is connected in a rotation-resistant manner to the first shaft 18.

The second valve flap 14 and the third valve flap 38 are therefore arranged between the first valve flap 12 and the fourth valve flap 40.

The first shaft 18 extends both through the second valve flap 14 and through the third valve flap 38 and also through the second shaft 20.

A second free-wheeling device 42, which connects the first shaft 18 to the second shaft 20, can be arranged between the third valve flap 38 and the fourth valve flap 40.

The second free-wheeling device 42 is functionally the same as the free-wheeling device 16 so that a rotation of the first valve flap 12 and of the fourth valve flap 40 in relation to the second valve flap 14 and to the third valve flap 38 by the free-wheeling angle a from the initial position is possible.

The positions of the valve flaps shown in Figures 5a to 5d can also be transferred to the second embodiment according to Figure 6, wherein the positions of the fourth valve flap 40 and of the third valve flap 38 correspond to the positions of the first valve flap 12 and of the second valve flap 14.

For example, the air duct which is controlled by the fourth valve flap 40 leads to a further side window of the vehicle and the air duct which is controlled by the third valve flap 38 leads centrally from the centre console into the vehicle's interior.

In addition to the embodiments of the valve flap sub- assembly 10 shown here, with two or four valve flaps, an optional different number of valve flaps are naturally also conceivable.

It is also conceivable to provide a plurality of free- wheeling devices with different free-wheeling angles in order to enable even more or larger free wheels between individual valve flaps.