Air-Conditioning Device and Method for Operating Same

Abstract

An air-conditioning device for air-conditioning a passenger compartment is provided. The air-conditioning device includes a cooling element for cooling air, an air duct downstream of the cooling element for guiding the air, a heating element downstream of the air duct for warming the air, a mixing zone downstream of the heating element, and multiple air outlets for discharging multiple partial air streams from the mixing zone into different regions of the passenger compartment. An additional cold air bypass is formed which is guided past the heating element for supplying additional cold air downstream of the heating element. As a result, the air-conditioning device in operation is particularly efficient and simultaneously simple in design and particularly cost-effective. Furthermore, the invention provides a method for operating the air-conditioning device.

Claims

1. An air conditioning unit for air conditioning of a passenger compartment, comprising: a cooling element for cooling air; an air duct downstream of the cooling element for guiding the air; a heating element downstream of the air duct for warming the air; a mixing zone downstream of the heating element; and a plurality of air outlets for discharging a plurality of partial air streams from the mixing zone into different regions of the passenger compartment, wherein an additional cold air bypass is formed, which is guided past the heating element, for supplying additional cold air downstream of the heating element.

2. The air conditioning unit according to claim 1, further comprising: a cold air metering element for adjusting a quantity of cold air which is supplied through the cold air bypass, wherein downstream of the cooling element is arranged a mixing air metering element for adjusting a warm air component which is conducted via the heating element and for adjusting a cooling air component which is guided past the heating element.

3. The air conditioning unit according to claim 2, wherein the cold air metering element and the mixing air metering element are adjusted by way of just one common final control element.

4. The air conditioning unit according to claim 3, wherein the final control element has two working ranges, which are a first working range, in which the mixing air metering element is adjusted, and a second working range, in which the cold air metering element is adjusted.

5. The air conditioning unit according to claim 2, wherein the cold air metering element and the mixing air metering element are mechanically coupled to each other.

6. The air conditioning unit according to claim 4, wherein the cold air metering element and the mixing air metering element are mechanically coupled to each other.

7. The air conditioning unit according to claim 2, wherein the mixing air metering element has an end position, and the cold air metering element is only opened and adjusted once the mixing air metering element is set in the end position.

8. The air conditioning unit according to claim 6, wherein the mixing air metering element has an end position, and the cold air metering element is only opened and adjusted once the mixing air metering element is set in the end position.

9. The air conditioning unit according to claim 1, wherein the heating element projects only partially into the air duct.

10. The air conditioning unit according to claim 2, wherein the heating element projects only partially into the air duct.

11. The air conditioning unit according to claim 1, wherein the heating element warms the air to maximally about 50 C.

12. The air conditioning unit according to claim 10, wherein the heating element warms the air to maximally about 50 C.

13. The air conditioning unit according to claim 1, wherein the cold air bypass feeds the cold air downstream of the mixing zone directly to one of the partial air streams.

14. The air conditioning unit according to claim 2, wherein the cold air bypass feeds the cold air downstream of the mixing zone directly to one of the partial air streams.

15. The air conditioning unit according to claim 1, wherein the air conditioning unit is operable in a summer mode and in a winter mode, and has a control unit which is configured such that the cold air metering element in the summer mode is completely closed and in the winter mode is set to supply the additional cold air via the cold air bypass.

16. The air conditioning unit according to claim 8, wherein the air conditioning unit is operable in a summer mode and in a winter mode, and has a control unit which is configured such that the cold air metering element in the summer mode is completely closed and in the winter mode is set to supply the additional cold air via the cold air bypass.

17. A method for operating an air conditioning unit with which a passenger compartment is air conditioned, the method comprising the acts of: feeding air to the passenger compartment; cooling the air by way of a cooling element; subsequently conducting the air through an air duct; subsequently warming the air by way of a heating element; subsequently conducting the air into a mixing zone; streaming the air via a plurality of air outlets and in a plurality of partial air streams into different regions of the passenger compartment; and guiding additional cold air past the heating element via a cold air bypass and supplying the additional cold air downstream of the heating element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a schematic view of an air conditioning unit.

[0033] FIG. 2 is a diagram showing an adjustment characteristic for metering elements of the air conditioning unit.

DETAILED DESCRIPTION OF THE DRAWINGS

[0034] In FIG. 1, an air conditioning unit 2, which serves for the air conditioning of a passenger compartment 4 of a vehicle (not shown in detail), is represented in schematized representation. In this context, a partial air stream T1, T2, T3 is respectively streamed into a plurality of regions of the passenger compartment 4 via air outlets 6. These partial air streams serve for the air conditioning of the different regions, which are also referred to as ventilation planes. Thus, in the illustrative embodiment which is shown here, the partial stream T1 is conducted along a windscreen (not represented in detail) of the vehicle, the partial stream T2 is discharged approximately at the chest height of an occupant (not shown), and the partial stream T3 into a footwell of the vehicle. In order to increase the comfort, the partial air streams T1, T2, T3 are temperature-controlled differently, i.e., have different temperatures. At least, in the illustrative embodiment which is shown here, the partial air stream T2 is a few C. cooler than the two other partial air streams T1, T3. For instance, the partial air stream T3 for the footwell may have a temperature of about 45 C., and the partial air stream T2 at the chest height of an occupant only about 35 C. The partial air stream T1 may have, for instance, likewise a temperature of 45 C.

[0035] For the air conditioning, air L is firstly streamed into or drawn into the air conditioning unit 2 and initially passes through a cooling element 8, which serves to cool the air L and is connected to a refrigerating circuit (not shown) of the air conditioning unit 8. Downstream of the cooling element 8, the air L is conducted through an air duct 10 to a heating element 12, which serves to warm the air L and which is here configured as a heating heat exchanger, which is connected to a coolant circuit (not shown). In FIG. 1, the heating element projects only partially into the air duct 10, so that the air can be conducted via two different paths, namely as a cooling air component LK past the heating element 12 and/or as a warm air component LW through the heating element 12.

[0036] The air L is here distributed amongst the two paths by way of a mixing air metering element 14. The mixing air metering element 14 is here configured as a mixing air flap, which at the same time adjusts the cooling air component LK and the warm air component LW. However, an embodiment as two separate flaps is also contemplated. Both the cooling air component LK and the warm air component LW make their way downstream of the heating element 12 into a mixing zone 16. Depending on the temperature of the heating element 12, the air L is then here present as a stratified air stream, or the various air components LK, LW mix together. In the case of a stratification, in different regions of the mixing zone 16, partial air streams T1, T2, T3 of different temperature can then be tapped. Such a stratification requires, however, a sufficiently large temperature difference between the cooling air component LK and the warm air component LW, and a strong warming by way of the heating heat exchanger 12, which may then have a temperature of, for instance, up to 80 C., i.e., far above an actually required temperature, for instance the above-mentioned 45 C. However, this is usually detrimental to the efficiency of the air conditioning unit 2 and, in particular, of a heat pump (not shown in detail) of the air conditioning unit 2, which heat pump, inter alia, serves to supply the heating element 12 with heat. This heat pump extracts from the surroundings of the vehicle the heat used for the warming, for instance via an ambient cooler (not shown), and may be operated at particularly high power in the event of strong heating, whereby, correspondingly, the ambient cooler is also at risk of icing. This risk arises particularly at low external temperatures, for instance in the range from 7 to 0 C., i.e., in particular in winter.

[0037] In order to operate the air conditioning unit 2 particularly efficiently, however, in particular in winter mode, in the illustrative embodiment which is shown here the maximum temperature of the heating element 12 is limited to about 50 C. In order then however to provide various partial air streams T1, T2, T3 having different temperatures, in particular if there is no stratification of the air L in the mixing zone 16, the air conditioning unit 2 additionally has a cold air bypass 18, for the bypassing of the heating element 12 and for the supply of cold air K downstream of the heating element 12. The cold air K is here, in FIG. 1, extracted from the air L downstream of the cooling element 8. In the embodiment which is shown here, the cold air bypass 18 then opens out directly into one of the air outlets 6, so that the associated partial air stream T2 is additionally cooled and, correspondingly, a temperature difference in relation to the other two partial air streams T1 and T3 is generated. As a result, an increase in comfort is realized even in the here particularly cost-effective, simple and efficient air conditioning unit 2.

[0038] For the adjustment of the quantity of cold air K which is supplied, and thus ultimately for the adjustment of the temperature difference, in the cold air bypass 18 is arranged a cold air metering element 20, which is here configured as a bypass flap for opening and closing the cold air bypass 18, wherein intermediate positions are also possible. Usually the cold air metering element 20 is closed, additional cold air K being supplied only as needed. In other words, firstly the air L is appropriately influenced by way of the mixing air metering element 14, and the temperature and, if need be, a stratification in the mixing zone 16, is set. Only in such cases in which no suitable stratification is producible, and in order to operate the air conditioning unit 2, furthermore, as efficiently as possible, the cold air metering element 20 is adjusted. This is here in particular the case when the mixing air metering element 14 assumes an end position as shown in FIG. 1, and the whole of the air L is warmed via the heating element 12. A stratified air stream in the mixing zone 16 is then no longer possible, so that then, correspondingly, cold air K is supplied by adjustment of the cold air metering element 20 and by at least partial opening of the cold air bypass 18.

[0039] In order to design the air conditioning unit 2, furthermore, as cost-effectively and simply as possible, the separate controlling and adjustment of the cold air metering element 20 and of the mixing air metering element 14, i.e., of the two metering elements 14, 20, is dispensed with. Instead, both metering elements 14, 20 are adjusted by way of a common final control element 22, which in particular is an actuator, preferably a stepping motor. Here, the two metering elements 14, 20 are mechanically coupled to each other by the final control element 22 in such a way that a delayed adjustment is realized, in which, at a given point in time, only ever one of the metering elements 14, 20 is adjusted. These are thus adjusted in a time-staggered manner, namely specifically such that an actuation by the final control element 22 only leads to an adjustment of the cold air metering element 20 once the mixing air metering element is in the end position. The two metering elements 14, 20 are hence in total connected to each other via delayed kinematics, as discussed in paragraph [0021] above.

[0040] The final control element 22 is then configured such that an adjustment characteristic as shown in FIG. 2 is obtained. The adjustment characteristic here shows the setting of the respective metering element 14, 20 as a function of a setting of the final control element 22. The setting of the mixing air metering element 14 is in this case represented by the two characteristic lines K1, K2, wherein the characteristic line K1 shows a setting with respect to the warm air component LW, and the characteristic line K2 a setting with respect to the cooling air component LK. A third characteristic line K3 shows the setting of the cold air metering element 20. Here a setting of 100% corresponds to a complete opening, a setting of 0% corresponds to a closed state.

[0041] According to FIG. 2, the final control element 22 has two working ranges A1, A2, namely a first working range A1, in which only the mixing air metering element 14 is adjusted, i.e., a ratio of the air components LK, LW which stream into the mixing zone 16, and a second working range A2, in which only the cold air metering element 20 is adjusted. Here the mixing air metering element 14 is located on the border between the two working ranges A1, A2, and beyond the complete working range A2 in the end position, as illustrated particularly by the characteristic line K1. This juxtaposition of the working ranges A1, A2 is a fundamental feature of the delayed kinematics and of the mechanical and time-staggered coupling of the two metering elements 14, 20 by way of the common final control element 22. It here becomes clear that additional cold air K is only supplied via the cold air bypass 18 once a maximum heating of the air L obtains.

[0042] The air conditioning unit 2 further has, as shown in FIG. 1, a control unit 24, which, inter alia, serves to drive the final control element 22. This is driven in particular in dependence on an air conditioning requirement which arises, for instance, from a heating or cooling requirement with respect to the passenger compartment 4 and/or an external temperature, which in particular is an expression of the weather conditions. Depending on the air conditioning requirement, the air conditioning unit 2 is then operated in summer mode or in winter mode.

REFERENCE SYMBOL LIST

[0043] 2 air conditioning unit [0044] 4 passenger compartment [0045] 6 air outlet [0046] 8 cooling element [0047] 10 air duct [0048] 12 heating element [0049] 14 mixing air metering element [0050] 16 mixing zone [0051] 18 cold air bypass [0052] 20 cold air metering element [0053] 22 final control element [0054] 24 control unit [0055] A1 first working range [0056] A2 second working range [0057] K1, K2, K3 characteristic line [0058] L air [0059] LK cooling air component [0060] LW warm air component [0061] T1, T2, T3 partial air stream

[0062] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.