Roof-mounted air-conditioning installation

Abstract

The invention relates to a roof-mounted air-conditioning installation (1) for a vehicle having a large internal volume, in particular a bus, which has at least one internal heat exchanger unit (2, 2') having a plurality of radial fans (6, 6') that serve to draw in air from the vehicle interior (10) via intake openings (11, 11') provided in the vehicle roof (9) in such a way that it flows through an internal heat exchanger (5, 5') and is then returned to the vehicle interior through at least one blow-out duct (16, 16'). In order to achieve a lower noise level, according to the invention the at least one blow-out duct has at least one through-opening in at least one of its side walls, which creates a sound-permeable connection to a sound absorption chamber (27, 28) arranged next to the blow-out duct.

Description

[0001] Spheres Germany GmbH S 556 -S / s

[0002] Roof-mounted air conditioning

[0003] The invention relates to a roof-mounted air conditioning system for a vehicle with a large interior volume, in particular a bus, according to the preamble of claim 1.

[0004] Modern rooftop air conditioning systems, according to the state of the art, essentially comprise the components of a refrigerant circuit, which include at least two heat exchangers, a usually electrically driven compressor, one or more expansion devices, electrically controlled valves, and pipe and / or hose lines that connect these units in terms of flow.

[0005] Depending on their design, such roof-mounted air conditioning systems can be configured either for cooling the vehicle interior alone or for heating or cooling it. Depending on the current operating mode (cooling or heating), each of the at least two heat exchangers can be used as either a condenser or an evaporator. Therefore, these terms are avoided in the following description, and the designations "external heat exchanger" and "internal heat exchanger" are used instead. Their function is preferably reversed by using controllable valves to reverse the refrigerant flows.

[0006] Often, two elongated, cuboid-shaped internal heat exchangers are used, positioned to the left and right of the longitudinally extending vehicle center axis and symmetrically to it, standing on the base trays of internal heat exchanger housings so that their longitudinal directions extend parallel to the vehicle's longitudinal axis. When installed, these base trays are located a short distance above the vehicle roof.

[0007] In each of the two interior heat exchanger housings, several radial fans, whose speed is controllable, are arranged at intervals along a line on the base tray next to the interior heat exchanger. This line runs parallel to the vehicle's longitudinal axis when the roof-mounted air conditioner is installed. During operation, the radial fans draw air from the vehicle interior through aligned, sealed intake openings located in both the vehicle roof and the base tray. This air flows through the corresponding interior heat exchanger and is then returned to the vehicle interior through exhaust ducts, also sealed, which extend through the base tray and the vehicle roof. Outside air can be mixed with this airflow as needed, and the volume of this mixture can be adjusted using controllable flaps.

[0008] Frequently, the space between the two inner heat exchanger housings contains a plate-shaped, horizontally oriented outer heat exchanger, also extending longitudinally in the vehicle, and an axial fan assembly. This assembly ensures that air flows through the outer heat exchanger, drawn in from the surroundings and released back into them after heat exchange. In current technology, the airflows generated by the radial fans are associated with a flow noise that is perceived as unpleasant, especially in electrically powered vehicles where the background noise of a combustion engine is absent. While attempts have been made to acoustically optimize the radial fans, these have not yielded entirely satisfactory results.While it is possible in principle to reduce the noise level of the radial fans by decreasing their rotational speed, this also reduces the volume of air flowing through the internal heat exchangers per unit of time, and thus the cooling or heating effect of the rooftop air conditioning system.

[0009] In contrast, the invention is based on the objective of further developing a rooftop air conditioning system of the type mentioned above in such a way that the airflow noise level of the radial fans in the vehicle interior is significantly reduced, regardless of their rotational speed.

[0010] To solve this problem, the invention provides the features set out in claim 1.

[0011] Because a side wall of at least one discharge duct has at least one through-opening that establishes a sound-permeable connection to a sound absorption chamber arranged next to the discharge duct, at least some of the sound energy carried by the airflow moving through this discharge duct can enter the sound absorption chamber and be absorbed there.

[0012] In this context, a sound absorption chamber is understood to be a cavity which, apart from at least one opening that provides a sound-permeable connection to an adjacent exhaust duct, is closed in such a way that the air conveyed by the radial fans cannot flow through it in such a way that it enters through one opening and exits through a second. By linguistic analogy to a "dead end," such a sound absorption chamber can therefore also be called a "dead-end chamber."

[0013] Preferably, one side wall of several, and in a particularly preferred manner of all, discharge shafts has a through-opening that provides a sound-permeable connection to a sound absorption chamber provided next to the respective discharge shaft.

[0014] By preferably providing two through-openings in the side wall(s) of at least one discharge shaft, each of which establishes a sound-permeable connection to one of two sound absorption chambers opposite each other with respect to the discharge shaft, increased sound absorption can be achieved, in particular, by the sound absorption chambers having different sizes and / or different cross-sections.

[0015] If the radial blowers are positioned such that their associated discharge ducts lie on a line parallel to the longitudinal direction of the vehicle, the sound absorption chambers can be arranged transversely to the longitudinal direction of the vehicle next to the discharge ducts and preferably connected to one another in such a way that they form a single, continuous sound absorption chamber extending in the longitudinal direction of the vehicle and associated with several discharge ducts. Preferably, each of the through-openings that establishes a connection between a discharge duct and a sound absorption chamber arranged next to it is covered by a sound-permeable barrier wall, which may consist of an open-pore nonwoven fabric, an open-cell polyurethane foam, or the like.This allows the sound energy carried by the airflow in the discharge duct to enter the respective sound absorption chamber unhindered, without dust or other dirt particles accumulating in it.

[0016] Since these sealing walls may become dirty, they are preferably attached in a detachable manner so that they can be easily removed for cleaning or replacement with new sealing walls.

[0017] Advantageously, at least one sound absorption chamber is arranged next to the associated exhaust duct in the longitudinal direction of the vehicle and preferably outside the vehicle interior.

[0018] The invention is described below with reference to exemplary embodiments and the drawing; in this drawing:

[0019] Fig. 1 shows a schematic sectional view, transverse to the longitudinal direction of the vehicle, through a roof-mounted air conditioning system conforming to the state of the art.

[0020] Fig. 2 shows a view of the right side area of ​​a rooftop air conditioning unit equipped with sound absorption chambers according to the invention, corresponding to Fig. 1.

[0021] Fig. 3 shows a top view of a plane supporting a series of radial fans arranged along a line extending in the longitudinal direction of the vehicle.

[0022] Fig. 4 shows a view of a plane lying below the plane of Fig. 3, which in particular shows the discharge ducts belonging to the radial blowers of Fig. 3, and

[0023] Fig. 5 shows a perspective, partially cut oblique view of the underside of a base tray of an internal heat exchanger unit of a rooftop air conditioning system according to the invention, with several discharge chutes and sound absorption chambers arranged next to them.

[0024] In the figures, identical or corresponding parts or assemblies are provided with the same reference numerals, and essentially only those components or assemblies necessary for understanding the invention are shown.

[0025] In the sectional view shown in Fig. 1, perpendicular to the longitudinal direction of the vehicle, of a roof-mounted air conditioning unit 1 corresponding to the prior art, only the two internal heat exchanger units 2, 2' are shown. These are arranged symmetrically to the left and right of the vehicle's central longitudinal axis at a distance from each other such that a central free space FR is formed between them, shown here with a reduced clear width in Fig. 1. The external heat exchanger unit and the associated axial fans are positioned in this free space, which has been omitted here for clarity. Each of the two internal heat exchanger units 2, 2', which extend almost over the entire length of the roof-mounted air conditioning unit 1, has a housing base 3 or 3, respectively.3', which carries several assemblies, each of which includes an internal heat exchanger 5, 5' and the associated radial fans 6, 6' arranged one behind the other in the longitudinal direction of the vehicle with a mutual distance, of which only one can be seen in the section of Fig. 1.

[0026] The two floor trays 3, 3' are attached to the vehicle roof 9 at a small distance above it via seals 4, 4', leaving a small gap between the underside of the trays and the vehicle roof 9.

[0027] The radial blowers 6, 6' draw in air from the vehicle interior 10 in such a way that, as indicated by the recirculation arrows UL, it flows upwards through intake openings 11, 1T formed in the vehicle roof 9 and the floor trays 3, 3', arranged in alignment with each other, into a mixing chamber 12, 12' formed in the housing of the respective interior heat exchanger unit 2 or 2', to which a variable proportion of fresh air FL can be supplied from above by means of a controllable flap arrangement 14, 14', which is only symbolically indicated.

[0028] Under the suction action of the radial blower 6 or 6', the mixed air flows from the mixing chamber 12 or 12' through the interior heat exchanger 5 or 5', through discharge ducts 16, 16' and the openings 17, 17' in the vehicle roof 9 connected to these, into an air distribution box 18 or 18', which serves to distribute the air evenly in the longitudinal direction of the vehicle. From this, the air conditioned by the interior heat exchanger 5, 5' returns to the vehicle interior 10 through air outlet openings formed in the floor and side wall of the air distribution box 18, 18', as indicated by the return air arrows RL.

[0029] In the rooftop air conditioning unit 1 shown, the discharge ducts 16, 16' have four walls, of which only the left and right side walls 20, 20' and 21, 2T respectively are visible in the section of Fig. 1. These are connected to each other by front and rear walls not visible here, such that an approximately rectangular cross-section of the respective discharge duct 16, 16' is obtained transversely to the direction of airflow.

[0030] With reference to Fig. 2, the modifications made to the rooftop air conditioning unit 1 shown in Fig. 1 according to the invention will now be described. For the sake of simplicity, only the right side of the arrangement is shown here, and it is understood that the opposite left side of a rooftop air conditioning unit 1 according to the invention can be designed in a corresponding manner.

[0031] The essential difference between a roof-mounted air conditioning system 1 conforming to the prior art and one according to the invention is that, in the latter, passage openings are provided in the opposing left and right side walls of the discharge duct 16, viewed in the longitudinal direction of the vehicle, which are closed by sound-permeable covers 23 and 24. The covers 23, 24 can, for example, consist of an open-cell polyurethane foam or an open-pore nonwoven fabric.

[0032] The through-openings establish a sound-permeable connection to sound absorption chambers 27 and 28 located next to the discharge duct 16, into which sound energy can enter, carried by the air flowing through the discharge duct 16, as indicated by the arrows SE. In addition to the through-opening that establishes a sound-permeable connection to the associated discharge duct 16, 16', the sound absorption chambers 27 and 28 have no further openings, so that no airflow can form in any of them that could generate flow noise.

[0033] The sound absorption chambers 27 and 28 can be partially or completely filled with sound-absorbing material not shown here.

[0034] However, it is also possible to design them as cavities containing essentially only air with sound-reflecting walls, in which the penetrating sound energy forms standing waves that cancel each other out. Such self-cancellation of the sound energy can be achieved over a broad frequency range due to the approximately triangular or trapezoidal cross-section of the sound absorption chambers 27 and 28, respectively.

[0035] Figures 3 and 4 show top views of two levels 30 and 31 arranged one above the other in the assembled state of the roof-mounted air conditioning unit 1, approximately congruent with each other. Three double radial fans 33 are mounted on the upper level 30 shown in Figure 3. These fans draw air from the vehicle interior upwards through an intake opening 11 extending over the entire length of the assembly, perpendicular to the plane of the drawing. The air then flows horizontally through the interior heat exchanger 6 and enters the discharge ducts 16 visible in Figure 4 through inlet openings (concealed in Figure 3 by the double radial fans 33). The discharge ducts 16 then direct the air perpendicularly back into the vehicle interior in Figure 4.The 4 side walls 20 of the discharge shafts 16 shown below have through openings not visible in this sectional view, each provided with a sound-permeable cover 23, which establish a sound inlet connection to a common sound absorption chamber 27 extending over the entire length of the arrangement.

[0036] However, it is also possible to design a separate sound absorption chamber for each discharge shaft 16, which is separate from the other absorption chambers.

[0037] In the example of a floor tray 3 shown in Fig. 5, four discharge chutes 16 are depicted, each of which has a side wall 20 oriented towards the center of the vehicle, in which a through-opening 36 is formed, through which it is connected to a sound absorption chamber 27. Each discharge chute 16 can be associated with a separate sound absorption chamber 27, of which only the foremost, sectioned sound absorption chamber 27 is visible in Fig. 5; alternatively, all these sound absorption chambers can be connected to each other in such a way that they form a continuous cavity extending in the longitudinal direction, as indicated by the dashed lines 38.

[0038] Here too, it is preferred that each of the passage openings 36 has a sound-permeable cover 23, which has been omitted in Fig. 5 for the sake of clarity.

[0039] In this embodiment, no further sound absorption chambers are provided on the sides of the discharge ducts 16 opposite the side walls 20.

[0040] In the embodiments described so far, the base trays 3, 3' of the internal heat exchanger units 2, 2' are adapted to the shape of the vehicle roof 9 in such a way that, in the mounted state of the roof-mounted air conditioning unit 1, there are only minimal gaps between the base trays 3, 3' and the vehicle roof 9.

[0041] Depending on the shape of the vehicle roof, larger gaps may be required, which are bridged by the exhaust ducts. In this case, the absorption chambers can be arranged below the underside of the base trays of the internal heat exchanger units and, for example, be designed so that their respective ceiling wall is formed by the base tray and / or their respective bottom wall by the vehicle roof. This can be achieved, for example, by clamping appropriately shaped components, possibly made of flexible, sound-absorbing material, between the underside of the base tray and the vehicle roof. A sound absorption chamber is then formed around the resulting exhaust ducts at a radial distance, using a suitable material.

[0042] So far, specific reference has only been made to discharge ducts with a horizontal cross-section in the installed state of the rooftop air conditioning unit, which has a substantially rectangular shape. However, the advantages resulting from the sound absorption chambers according to the invention can also be achieved with discharge ducts with a circular or oval horizontal cross-section.

[0043] Reference symbol list:

[0044] 1 rooftop air conditioning unit

[0045] 2.2' Internal heat exchanger unit

[0046] 3, 3' floor trays

[0047] 4, 4' seals

[0048] 5.5' Internal heat exchanger

[0049] 6.6' Radial blower

[0050] 9 Vehicle roof

[0051] 10 Vehicle interior

[0052] 11, 11' Intake openings

[0053] 12, 12' Mixing room

[0054] 14, 14' Flap arrangement

[0055] 16, 16' Outlet shaft

[0056] 17, 17' Openings in the vehicle roof

[0057] 18, 18' air distribution boxes

[0058] 20, 20' left side wall

[0059] 21, 21' right side wall

[0060] 23 and 24 sound-permeable cover

[0061] 27 and 28 Sound absorption chamber

[0062] 30, 31 levels

[0063] 33 twin radial blowers

[0064] 36 Passage opening

[0065] 38 dashed line

Claims

Spheres Germany GmbH S 556 -S / s Patent claims 1. Roof-mounted air conditioning system (1) for a vehicle with a large interior volume, in particular a bus, comprising at least one interior heat exchanger unit (2, 2') with several radial fans (6, 6') which serve to draw air from the vehicle interior (10) via intake openings (11, 1T) provided in the vehicle roof (9) in such a way that it flows through an interior heat exchanger (5, 5') in order to then be returned to the vehicle interior (10) through at least one discharge duct (16, 16'), characterized in that the at least one discharge duct (16, 16') has at least one through-opening in at least one of its side walls which establishes a sound-permeable connection to a sound absorption chamber (27, 28) arranged next to the discharge duct.

2. Roof-mounted air conditioning system (1) according to claim 1 , characterized in that the sound absorption chamber (27, 28) is arranged laterally next to the associated discharge duct when viewed in the longitudinal direction of the vehicle.

3. Rooftop air conditioning unit (1) according to claim 1 or 2, characterized in that the sound absorption chamber (27, 28) is arranged above a floor tray (3) of the rooftop air conditioning unit (1).

4. Rooftop air conditioning unit (1) according to claim 1 or 2, characterized in that a sound absorption chamber is arranged below a floor tray (3) of the rooftop air conditioning unit (1) and above the vehicle roof (9).

5. Roof-mounted air conditioning system (1) according to claim 4, characterized in that the bottom wall of a sound absorption chamber is formed by the vehicle roof (9).

6. Roof-mounted air conditioning system (1) according to one of claims 1 to 4, in which at least some of the radial blowers (6, 6') are arranged such that associated discharge ducts (16, 16') are positioned along a line parallel to the longitudinal direction of the vehicle, characterized in that at least several of these discharge ducts (16, 16') each have at least one through-opening in two opposing side walls (20, 21 ; 20' 21) which establishes a connection to each sound absorption chamber (27, 28).

7. Roof-mounted air conditioning system (1) according to claim 1 or 2, characterized in that the sound absorption chambers (27), which are arranged on the same side of several discharge ducts (16, 16'), are connected to each other in such a way that they form a continuous sound absorption chamber common to these discharge ducts (16, 16') and extending in the longitudinal direction of the vehicle.

8. Rooftop air conditioning system (1) according to one of the preceding claims, characterized in that through-openings which establish a connection between the respective discharge duct (16, 16') and a sound absorption chamber (27, 28) arranged next to it are closed by a sound-permeable cover (23, 24).

9. Rooftop air conditioning system (1) according to claim 7, characterized in that the sound-permeable cover (23, 24) consists of an open-pore nonwoven fabric or open-cell polyurethane foam.

10. Rooftop air conditioning system (1) according to one of the preceding claims, characterized in that sound-absorbing means are provided inside sound absorption chambers (27, 28).

11. Rooftop air conditioning system (1) according to one of claims 1 to 9, characterized in that the inner walls of sound absorption chambers (27, 28) consist of a sound-reflecting material, and that the dimensions of these sound absorption chambers (27, 28) are selected such that standing, self-quenching sound waves are formed in them for a multitude of sound frequencies.

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