Protective grille and outdoor heat pump unit

Description

State of the art

[0001] Devices for passing an airflow through a component of an air conditioning system or a heating system, in particular a heat pump outdoor unit, are known from the prior art.

[0002] JP 2007 139214 A discloses a fan guard for an outdoor unit of an air conditioner with radial and annular struts. The struts direct the airflow conveyed into the outside environment and fan it out, thereby distributing the air over a large area. Disclosure of the invention

[0003] The invention is disclosed in claim 1.

[0004] An air conditioning system or heating system is understood to be, in particular, a system for heating and / or cooling, or more generally, for temperature control, of rooms in an apartment or building, or of the air in these rooms. Additionally or alternatively, an air conditioning system or heating system can also be used to heat domestic hot water. For example, a heat pump system constitutes such an air conditioning or heating system. A component, in this context, is understood to be, in particular, a part, assembly, or subunit of the air conditioning or heating system. The component is, in particular, used for the purpose of heat transfer and / or ventilation and / or exhaust air flows through it, and may include an air-flowable heat exchanger. For example, a heat pump outdoor unit constitutes such a component.In this context, an outdoor heat pump unit is understood to be, in particular, an air-flowing component of a heat pump system installed in an environment, such as the exterior of a building. This component allows heat to be transferred from an airflow to a heat transfer fluid, and / or vice versa. Specifically, the heat transfer fluid can be used to heat or cool rooms in a building and / or to heat domestic hot water. Alternatively, an air outlet device can also be considered such a component. In this context, an air outlet device is understood to be a device for discharging or blowing an airflow from an air conditioning or heating system into an environment, such as the exterior or a room of a building.

[0005] A device for conveying an airflow is understood to mean, in particular, a device for drawing in (especially by suction) the airflow at an inlet opening, for guiding the airflow in an air duct, and for expelling (especially by blowing) the airflow at an outlet opening. The outlet opening is also called the orifice. The device is, in particular, encompassed by the component. Alternatively, the device may be designed separately from the component. Free outflow, in this context, is understood to mean, in particular, outflow into an environment that is unobstructed, at least in the immediate vicinity of the outlet opening. Apart from the inlet opening and the outlet opening, the air duct is, in particular, closed by means of a duct wall. An outlet plane, in this context, is understood to mean, in particular, the plane defined by an edge circumferentially surrounding the edge of the outlet opening.In this context, an air duct axis is understood to mean, in particular, the central or longitudinal axis of the air duct. A main flow direction is understood to mean, in particular, the direction in which the airflow flows on average over time. The main flow direction can, in particular, run in the direction of the air duct axis. The main flow direction can, in particular, coincide with the air duct axis.

[0006] In this context, a protective grille is understood to be, in particular, an access barrier covering the outlet opening. The protective grille prevents hands from reaching inside and objects or small animals from the surrounding area from falling into the air duct. Specifically, the protective grille should not significantly impede the airflow through the air duct or through the grille itself. The protective grille can be, in particular, essentially a disc-shaped element and have the form of a flat cuboid or a flat cylinder, the major dimensions of which (width and length or diameter) run parallel to a principal plane of extension of the protective grille. A principal axis of the protective grille is transverse, in particular perpendicular, to the principal plane of extension of the protective grille and runs essentially through the geometric center of gravity of the protective grille.The protective grille is positioned at the outlet opening such that its main axis runs essentially along the air duct axis. In particular, the main axis of the protective grille and the air duct axis essentially coincide. The protective grille comprises two or more louvers that provide access protection.

[0007] The protective grille can, in particular, have a first protective grille section, especially one located radially inside, close to the air duct axis or main grille axis, and a second protective grille section, especially one located radially outside, farther from the air duct axis or main grille axis. The second section, in particular, can be air-permeable and have louvers. The first section, in particular, can be air-impermeable and have a round or square, lid-like cover.

[0008] In this context, a louver is understood to be, in particular, a substantially leaf-shaped or strip-shaped air guide element. The louvers are arranged, in particular, within the flat cuboid or cylindrical shape of the protective grille. The louvers are specifically designed to direct the airflow exiting the opening. A free airflow cross-section is formed between the louvers. The clear width of this free airflow cross-section is specifically selected to reliably prevent hands from reaching inside and objects or small animals from the surrounding area from falling into the air duct.

[0009] The term "essentially" here can be understood to mean, in particular, "except for manufacturing tolerances." Furthermore, "essentially" here can be understood to mean, in particular, a maximum deviation of 5% to 15% from the total.

[0010] The term "conical" here refers in particular to a pointed cone or a pointed cone with a round base, or to a truncated cone with a large round and a small round base.

[0011] The term "pyramidal" here refers in particular to a pointed pyramid with a square base or a truncated pyramid with a large square base and a small square base.

[0012] The term "essentially conical or pyramidal" here refers in particular to a cone-like or pyramidal shape in which the contour of the lateral surface (for example, the channel wall contour or the displacement body contour) in axial section can be a straight line or can be concave or convex.

[0013] A ring-shaped lamella, as used here, refers specifically to a thin wall encircling a continuous opening, similar to a short section of a thin-walled tube with a round or square cross-section – with the difference that the wall is not cylindrical (like the tube wall of a round tube) or prismatic (like, for example, the tube wall of a square tube), but rather widens conically (see below, first type of lamella) or truncated pyramidally (second type of lamella). The thin surrounding wall corresponds to the lamella.

[0014] In one type of louver, the louvers can be designed as round rings of varying diameters, arranged essentially coaxially with the air duct axis and / or the main axis of the protective grille. The louver rings are, in particular, essentially as wide as the flat cylindrical shape of the protective grille is high. The louvers are not parallel to each other, but rather exhibit different angles (different inclination angles) relative to the opening plane. Conceptually, such a louver resembles the lateral surface of a flat section of a cone, with different louvers forming the lateral surfaces of cone sections with varying opening angles and diameters.

[0015] In a second, alternative type of louver, a louver can be composed of several, essentially equal-length, straight louver segments arranged congruently around the air duct axis and / or the main axis of the protective grille, joining together, particularly at their respective ends, to form a continuous shape. Different louvers are composed of louver segments of varying lengths. In this way, the louvers are formed, in particular, as truncated pyramid-shaped, "angular rings" with square or regularly polygonal bases and varying widths and lengths. These are arranged essentially coaxially with the air duct axis and / or the main axis of the protective grille. The louvers are, in particular, essentially as wide as the height of the flat cuboid shape of the protective grille.The lamellae are not parallel to each other, but each has different lamella angles (different angles of inclination) to the opening plane. Conceptually, such a lamella is similar to the lateral surface of a flat section of a pyramid (with a square or regular polygonal base), whereby different lamellae are formed as lateral surfaces of pyramid sections with different opening angles and different diameters.

[0016] A lamella or lamella segment, in particular, has a strip-like shape – either elongated or curved – with a small thickness D (e.g., D = 3 millimeters), a significantly greater width (e.g., 5–15 D), and a much greater length (e.g., greater than 50 D). Here, a lamella plane is understood to be a surface spanned by the width and length of the lamella.

[0017] The lamella angle L is measured between the respective lamella plane and the opening plane, in the quadrant facing away from the air duct axis and / or protective grille main axis and towards the installation environment.

[0018] The phrase "that the lamella angles of at least two lamellae are different from each other" means that the lamella angles are recognizably and measurably different from one another. For example, the difference in the lamella angles of adjacent lamellae can preferably be at least 2 degrees, and more preferably at least 5 degrees. If three or more lamellae are present, the lamella angles increase successively from one lamella to the next.

[0019] This invention provides an improved protective grille. The device is particularly suitable for influencing, and especially directing, the airflow exiting the installation environment. Even with varying airflow rates, flow separation from the duct wall, the louvers, and / or the displacement body does not occur. In particular, the airflow noise is exceptionally quiet. This allows the device, and consequently the component, to be subjected to larger airflows, or to be built smaller and more compact.

[0020] In this device (or rather, the protective grille), the angle L of a louver is determined as a function of the perpendicular distance R of the louver from the main axis of the protective grille. The angle L is greater with a greater perpendicular distance R. A maximum angle LMAX of, in particular, 90 degrees is not exceeded.

[0021] In such a protective grille, the radially inner lamella is arranged at a relatively shallow angle relative to the opening plane of the air duct or the main plane of extension of the protective grille, while each outer lamella is arranged at a slightly steeper angle. This results in a particularly favorable airflow pattern above the outlet area of ​​the protective grille.

[0022] The airflow is stabilized, and kinetic flow losses are minimized.

[0023] The radially internal, flatly arranged louvers obstruct a line of sight from the surroundings in a normal direction to a fan impeller.

[0024] A vertical distance of a lamella is understood to be a radial distance from the main axis of the protective grille.

[0025] A vertical distance of a lamella of the second is understood to be the shortest distance of the straight lamella sections from the main axis of the protective grille.

[0026] For example, the distance can be measured from the air duct axis and / or the main axis of the protective grille to the nearest louver edge or to the geometric center of gravity of the louver.

[0027] The device for conveying an airflow can include a fan, in particular an axial fan, for conveying the airflow, wherein the fan is arranged, in particular, in an upstream section of the air duct. An upstream section of the air duct is understood to be, in particular, a region upstream of the outlet opening and the protective grille. An axis of rotation of the fan can, in particular, extend along the axis of the air duct. Preferably, the axis of rotation and the axis of the air duct coincide.

[0028] In a preferred embodiment of the device (or the protective grille), the lamella angle L of a lamella is determined as a function of the axial distance of the lamella from the fan. The lamella angle L is larger with a greater axial distance. A maximum lamella angle LMAX of, in particular, 90 degrees is not exceeded. For example, the distance can be measured from the nearest edge of a fan impeller to the nearest lamella edge or to the geometric center of gravity of the lamella.

[0029] In another preferred embodiment of the device (or the protective grille), the size of the lamella angle L of a lamella is determined as a function of the vertical distance R such that L = 75083 R 3 − 58290 R 2 + 15151 R − 1261 , 8 where R is the magnitude of the vertical distance of the lamella from the air duct axis, specified in meters, and L has the unit degrees.

[0030] In a further preferred embodiment of the device (or the protective grille), the size of a dimensionless lamella angle ℓ of a lamella is determined as a function of the dimensionless vertical distance r, such that l = 3.8628 × 10 − 4 e 7 , 8242 r is. Here, ℓ and r are determined according to the equations l = L − L - min / L - max − L - min r = R / R - max calculated. R is the value of the vertical distance of the lamella from the air duct axis, specified in meters, and L is specified in degrees.

[0031] R-max is the perpendicular, in particular radial, distance of the duct wall from the air duct axis. R-min is the perpendicular, in particular radial, distance of an outer contour of a displacement body from the air duct axis. L-max is the lamella angle of the outermost lamella, in particular the one touching the duct wall; for L-max, the wall angle W of the duct wall can also be specified. L-min is the lamella angle of the innermost lamella, in particular the one touching the displacement body; for L-min, the displacement body angle V of the displacement body can also be specified.

[0032] As an example, consider a device where the duct wall at the air duct outlet has a radial distance R-max = 0.32 meters from the air duct axis, where the wall angle W = L-max = 80 degrees and the displacement body angle V = L-min = 53 degrees. Find the lamella angle L for a lamella whose radial distance R = 0.29 meters.

[0033] The dimensionless radius is calculated from the given dimensions as follows: r = 0 , 29 / 0 , 32 = 0 , 9 .

[0034] This allows the dimensionless lamella angle to be calculated as follows: l = 3.8628 × 10 − 4 e 7.8242 × 0 , 9 = 0 , 442 .

[0035] This determines the desired lamella angle. L = l L - max − L - min + L - min = 65 Grad .

[0036] In another preferred embodiment of the device (or the protective grille), the size of the dimensionless lamella angle ℓ of a lamella is greater than or equal to a lower limit value. l ug = 3.8628 × 10 − 4 e 7.8242 1.05 r as less than or equal to an upper limit l og = 3.8628 × 10 − 4 e 7.8242 × 1.05 r

[0037] In this process, ℓ and r are determined according to the equations l = L − L - min / L - max − L - min r = R / R - max calculated. R is the value of the vertical distance of the lamella from the air duct axis, specified in meters, and L is specified in degrees.

[0038] The device for allowing an airflow preferably has an airtight channel wall for the outer boundary of the air channel, particularly radially. The channel wall can be designed as the surface of a wall element surrounding, and in particular forming, the air channel.

[0039] In a further preferred embodiment of the device, a wall angle W of the duct wall in the region of the air duct's outlet, particularly the outlet to the environment, measured between a duct wall contour in axial section and the outlet plane, is determined essentially like a lamella angle L of a lamella with the same perpendicular distance R from the air duct axis. A maximum wall angle WMAX of, in particular, 90 degrees is not exceeded. A duct wall contour is understood to be, in particular, the geometric profile of a surface of the duct wall near the outlet in the direction of flow. An axial section is understood here to be, in particular, a longitudinal section through the device in which the air duct axis lies in the section plane. In this way, the wall angle of the duct wall integrates harmoniously into the sequence of inclined lamellae and supports the flow effect of the lamellae on the airflow.

[0040] The device for allowing an airflow preferably includes a displacement body arranged coaxially within the air duct. In particular, the protective grille has a displacement body arranged coaxially to the main axis of the protective grille. The displacement body has the shape of a cone or truncated cone, or a pyramid or truncated pyramid. In particular, the apex of the displacement body points upstream, and the apex can also be a small base of a truncated cone or pyramid. The displacement body widens, in particular, in the main flow direction from the apex and its base contacts the protective grille. Thus, the displacement body limits the air duct inwards and displaces the airflow towards the duct wall. The air duct runs, in particular, between the inner displacement body and the outer duct wall.

[0041] In a further preferred embodiment of the device (or the protective grille), the displacement body angle V of the displacement body in the region of the air duct opening, particularly the opening to the environment, measured between a displacement body contour in axial section and the opening plane, is determined essentially like a lamella angle L of a lamella at the same perpendicular distance R from the air duct axis. A displacement body contour is understood to be, in particular, the geometric profile of a surface of the displacement body near the opening in the direction of flow. An axial section is understood here to be, in particular, a longitudinal section through the device in which the air duct axis lies in the section plane. In this way, the displacement body angle of the displacement body integrates harmoniously into the sequence of inclined lamellae and supports the flow effect of the lamellae on the airflow.

[0042] The invention is disclosed in claim 1.

[0043] This invention provides a protective grille that is an improvement over the prior art. The grille is particularly suitable for influencing, and especially directing, the airflow exiting an installation environment. Even with varying airflow volumes, flow separation from the louvers and / or the displacement body does not occur. In particular, the airflow noise is exceptionally quiet. This allows the grille to be designed with larger airflows or to be built smaller and more compact. The invention further relates to a heat pump outdoor unit for heat transfer between an airflow and a heat transfer fluid, especially a refrigerant.

[0044] It is proposed that the heat pump outdoor unit comprises a device according to the invention for flowing with an airflow and / or a protective grille according to the invention for covering an air duct.

[0045] For injection molding a protective grille for the air-permeable covering of an air duct, wherein the protective grille has at least two substantially ring-shaped lamellae arranged at different vertical distances R from a main axis of the protective grille, an injection molding tool is conceivable with a lower tool half and a separately formed upper tool half, wherein the injection molding tool is provided in a closed state for injection molding the protective grille and in an open state for removing the cast protective grille.

[0046] It is further conceivable that each mold half has a substantially closed base plate; that each mold half has an annular protrusion on the side of the base plate facing the protective grid to be cast, with the protrusions being concentric to each other; that the protrusions of the two mold halves are arranged radially offset from each other and interlock when the injection mold is closed; that the protrusions have a right-angled trapezoidal cross-section with a right-angled flank and an oblique flank; that the flank angles of the oblique flanks of the different protrusions are different from each other and correspond to the lamella angles of the lamellae to be cast; that a space for the formation of a lamella is formed between each pair of corresponding oblique flanks of the two mold halves;that the corresponding vertical flanks of the two tool halves are designed to slide along each other when the injection mold is opened and closed.

[0047] For example, these are heat pump outdoor units, designed to be installed in the outdoor environment of a building. Component 100 has a device with an air duct (neither of which are visible here) through which an airflow flows during operation. A protective grille 120 is visible on the front of the component, which covers the opening of the air duct behind it, allowing air to pass through to the installation environment 1.

[0048] The airflow 2 flows through the air duct, the opening, and the protective grille 120 into the installation environment 1. A closed, lid-like baffle 124 is arranged in a first, radially inner section of the protective grille 120. Several ring-shaped louvers 122 are arranged in a second, radially outer section of the protective grille. A free flow cross-section for the airflow 2 is formed between the louvers 122. Figure 1a Figure 1 shows a protective grille 120 that is round in plan view (actually flat cylindrical) with radially spaced, circumferential, round lamellar rings 122, which are arranged in the opening plane of the air duct. Figure 1b Figure 1 shows a protective grille 120 that is square in plan view (actually flat cuboid) with spaced, circumferential angular lamellar rings 122, which are arranged in the opening plane of the air duct.

[0049] Figure 2Figure 1 shows a longitudinal section through a component 100 of an air conditioning or heating system, for example, a heat pump outdoor unit. The component 100 comprises a housing 102, a device 110 for allowing an airflow 2 through the component 100 with an air duct 112 and a protective grille 120, an air-flowable heat exchanger 104 for transferring heat between the airflow 2 and a heat transfer fluid, and a wall element 106 for forming the duct wall 114 that delimits the air duct 112. A fan 116 draws the airflow 2 from the installation environment 1. The airflow 2 flows with a main flow direction 3 through the heat exchanger 104, a first section 112-1 of the air duct 112, the fan 116, a second section 112-2 of the air duct 112, and the protective grille 120. The air duct 112 widens in a conical or pyramidal shape in the main flow direction 3 of the airflow 2 and opens into the installation environment 1.The protective grille 120 is arranged at the opening 118 of the air duct 112 and covers it in a way that allows air to pass through. The airflow 2 flows freely between the louvers 122 of the protective grille 120 into the surrounding environment 1.

[0050] The inclination of the louvers 122 relative to the air duct axis 113 and / or the main axis of the protective grille 126 (which coincide here) can be seen, as well as a louver angle L of an exemplary louver 122. The louver angle L is measured in particular between the respective louver plane 123 and the opening plane 118, especially in a quadrant facing away from the air duct axis 113 and / or the main axis of the protective grille 126 and towards the installation environment 1.

[0051] Figure 3Figure 1 shows two perspective views of a protective grille 120 from the front and rear. The protective grille 120 is designed, in particular, to provide an air-permeable cover for an air duct 112 for a device 110 through which an airflow 2 flows. The protective grille 120 is designed to be arranged in the area of ​​an opening of the air duct 112 into an environment 1. The protective grille 120 has four essentially coaxial and radially different distances R from the main axis 126 of the protective grille, which are essentially annular lamellae 122.

[0052] The lamella angles L of the four lamellae 122 are different from one another. The lamella angles L of the lamellae 122 are determined in particular as a function of their respective radial spacing R. The lamella angle L is larger with a larger radial spacing R.

[0053] The illustration shows a substantially conical displacement body 130, adjacent to the protective grille 120 and arranged coaxially with the main axis 126 of the protective grille. The displacement body 130, with its larger base area, abuts the flat cylindrical shape of the protective grille 120. The aperture 124 is located on the front side in the center of the protective grille, adjacent to the larger base area of ​​the displacement body 130. Connecting webs 128 connect the lamellae 122 to form the assembly or component protective grille.

[0054] Figure 4Figure 1 shows an upper half of a protective grille 120 in axial section up to the main axis of the protective grille (126, axis of symmetry) and an edge region of the duct wall 114 of an associated air duct 112. The main axis of the protective grille 126 and the air duct axis 113 coincide on a substantially common axis. The protective grille 120 is designed, in particular, to provide an air-permeable cover for the air duct 112 for a device 110 through which an airflow 2 can pass. The protective grille 120 is designed to be arranged in the area of ​​an opening of the air duct 112 into an environment 1.

[0055] The protective grille 120 comprises five essentially coaxial and radially spaced (R) louvers 122 arranged at different distances from the main axis 126 of the protective grille. The first (inner) louver in radial sequence, with a louver angle L-1, forms an outer shell of the aperture 124 with a louver angle L-min. The last (outer) louver in radial sequence, with a louver angle L-5, forms an inner shell of the channel wall 114 with a louver angle L-max.

[0056] An outer sheath angle L-min of the aperture 124, measured between an aperture contour in axial section and the principal extension plane 127 of the protective grid 120, is determined essentially like the blade angle L-1 of the blade 122 with the same radial distance R-1 from the protective grid principal axis 126.

[0057] The louver angles L of the louvers 122 are different from one another. The louver angle L is measured – illustrated here using the third louver as an example – specifically between the respective louver plane 123 and the opening plane 118, particularly in a quadrant facing away from the air duct axis 113 and / or the main axis of the protective grille 126 and towards the installation environment 1. The louver angles L-1, L-2, L-3, L-4, L-5 of the louvers 122 are determined specifically as a function of their respective radial distances R-1, R-2, R-3, R-4, R-5. The louver angle L is larger with a larger radial distance R. For example, L-2 is larger than L-1 because R-2 is larger than R-1.

[0058] In the present case, the device 110 has a substantially conical displacement body 130 adjacent to the protective grille 120 and arranged coaxially to the main axis 126 of the protective grille. The displacement body 130 abuts a main extension plane 127 of the protective grille 120 with its larger base area. The airflow flows along the outer surface of the displacement body 130.

[0059] The displacement body angle V of the displacement body 130 in the immediate vicinity of the lamellae 122, measured between a displacement body contour in axial section and the principal extension plane 127 of the protective grille 120, is determined essentially like the lamella angle L-1 of the lamella 122 with the same radial distance R-1 from the main axis 126 of the protective grille. Here, the radial distance R is measured in the principal extension plane 127. The displacement body angle V of the displacement body 130 in the immediate vicinity of the lamellae 122 corresponds to the lamella angle L-min of the spatially associated lamella 122. The contours of the displacement body 130 and the first lamella 122 complement each other, in particular, to form a streamlined overall contour.

[0060] In the upper edge region of the protective grille 120, the adjacent airtight channel wall 114 of the device 110, through which an airflow 2 passes, can be seen. The channel wall 114 serves in particular as the radial, outer boundary of the air channel 112. A wall angle W of the channel wall 114 in the region of the opening of the air channel 112, in particular into the surroundings 1, measured between a channel wall contour in axial section and the opening plane 118, is determined essentially like a lamella angle L-max of a lamella 122 with the same radial distance R-5 from the air channel axis 113 (shown here as an alternating angle).

Claims

1. Protective grille (120) for a device (110) which serves for passage of an air stream (2) through a heat-pump outdoor unit (100) of an air-conditioning system or a heating system and has an air channel (112), for covering the air channel (112) in an air-permeable manner, in particular in relation to installation surroundings (1), having at least two substantially ring-shaped lamellae (122) which are arranged substantially coaxially and at a different perpendicular distance R from a protective-grille main axis (126), wherein lamella angles L of the at least two lamellae (122), measured in a quadrant which is formed between a respective lamella plane (123) and a main extent plane (127) of the protective grille (120) and is directed away from the protective-grille main axis (126) and is directed towards the installation surroundings (1), are different from one another, wherein the lamella angle L of a lamella (122) is determined as a function of the perpendicular distance R, characterized in that the lamella angle L is greater at a greater perpendicular distance R of the lamella (122) from the protective-grille main axis (126), wherein in particular a maximum lamella angle Lmax = 90 degrees is not exceeded.

2. Protective grille (120) according to Claim 1, characterized in that a size of the dimensionless lamella angle I of a lamella (122) is greater than or equal to a lower limit value l ug = 3.8628 × 10 − 4 e 7.8242 1.05 r and is less than or equal to an upper limit value l og = 3.8628 × 10 − 4 e 7.8242 × 1.05 r where I = L − L - min / L - max − L - min , r = R / R - max , wherein, for R, the magnitude of the perpendicular distance of the lamella (122) from the protective-grille main axis (126) is to be specified in the unit meter, and wherein L has the unit degree.

3. Protective grille (120) according to Claim 1 or 2, wherein the protective grille (120) has an, in particular substantially conical or pyramidal, displacement body (130) which is arranged coaxially with respect to the protective-grille main axis (126), characterized in that a displacement-body angle V of the displacement body (130) in a vicinity of the lamellae (122), measured between a displacement-body contour in an axial section and the main extent plane (127) of the protective grille (120), is determined substantially like a lamella angle L of a lamella (122) at the same perpendicular distance R from the protective-grille main axis (126).

4. Device (110) for passage of an air stream (2) through a heat-pump outdoor unit (100) of an air-conditioning system or a heating system, in particular for free outflow of an air stream (2) into installation surroundings (1), having • an air channel (112) which widens in a substantially conical or pyramidal manner, in particular in a main flow direction (3), and has an air-channel axis (113) and has an opening into installation surroundings (1), and • a protective grille (120) according to one of Claims 1 to 3 in the region of the opening, which protective grille is arranged transversely to the main flow direction (3) and serves as an air-permeable cover of the air channel (112), in particular in relation to the installation surroundings (1).

5. Device (110) according to Claim 4, having a fan (116), in particular an axial fan, for conveying the air stream (2), wherein the fan (116) is arranged in an upstream portion of the air channel (112), characterized in that the lamella angle L of a lamella (122) is determined as a function of an axial distance of the lamella (122) from the fan (116), wherein the lamella angle L is greater for a greater axial distance, wherein in particular a maximum lamella angle Lmax = 90 degrees is not exceeded.

6. Device (110) according to Claim 4 or 5, characterized in that a size of the lamella angle L of a lamella (122) is determined as a function of the perpendicular distance R in such a way that L = 75083 R 3 − 58290 R 2 + 15151 R − 1261.8 , wherein, for R, the magnitude of the perpendicular distance of the lamella (122) from the air-channel axis (113) is to be specified in the unit meter, and wherein L has the unit degree.

7. Device (110) according to one of the preceding claims, characterized in that a size of a dimensionless lamella angle I of a lamella (122) is determined as a function of the dimensionless perpendicular distance r in such a way that l = 3.8628 × 10 − 4 e 7.8242 r , where l = L − L - min / L - max − L - min , r = R / R - max , wherein, for R, the magnitude of the perpendicular distance of the lamella (122) from the air-channel axis (113) is to be specified in the unit meter, and wherein L has the unit degree.

8. Device (110) according to one of the preceding claims, wherein the device (110) has an air-impermeable channel wall (114) for, in particular radial, outer delimitation of the air channel (112), characterized in that a wall angle W of the channel wall (114) in the region of the opening of the air channel (112), in particular into the surroundings (1), measured between a channel-wall contour in an axial section and the opening plane (118), is determined substantially like a lamella angle L-max of a lamella (122) at the same perpendicular distance R-max from the air-channel axis (113), wherein in particular a maximum wall angle Wmax = 90 degrees is not exceeded.

9. Device (110) according to one of the preceding claims, wherein the device (110) has a displacement body (130) which is arranged centrally in the air channel (112) and which widens in a substantially conical or pyramidal manner, in particular in the main flow direction (3), and which serves for, in particular radial, inner delimitation of the air channel (112), characterized in that a displacement-body angle V of the displacement body (130) in the region of the opening of the air channel (112), in particular into the surroundings (1), measured between a displacement-body contour in an axial section and the opening plane (118), is determined substantially like a lamella angle L-min of a lamella (122) at the same perpendicular distance R-min from the air-channel axis (113).

10. Heat-pump outdoor unit (100) for transfer of heat between an air stream (2) and a refrigerant, characterized by a device for passage of the air stream (2) through the heat-pump outdoor unit according to one of Claims 4 to 9 and / or a protective grille (120) for covering an air channel (112) in an air-permeable manner according to one of Claims 1 to 3.