HEAT PUMP

Description

[0001] The present invention relates to a heat pump, in particular a heat pump designed for installation in an interior space.

[0002] In recent times, the search for climate-friendly refrigerants has intensified. However, a disadvantage of many climate-friendly refrigerants is their flammability. The use of such refrigerants, for example, in heat pumps, therefore leads to special safety requirements. To ensure that any refrigerant escaping from a refrigeration circuit does not accidentally ignite, a minimum volume or space is prescribed in which the escaping refrigerant is distributed to ensure adequate mixing.

[0003] Flammable refrigerant must therefore be safely removed from the heat pump in the event of a possible leak in the refrigerant circuit. It is advisable to pump the refrigerant as high as possible into the installation room. This reduces the required minimum area of ​​the room to ensure sufficient mixing so that the refrigerant concentration in the air is no longer flammable. According to standard 60335-2-40, there are three options for this: 1. Refrigerant escapes from the heat pump automatically at a certain height (without a fan). The refrigerant outlet height is the only factor that determines the minimum installation room size. The outlet height is defined as the height above which the sum of all openings in the device exceeds 5 cm². The higher the outlet height, the smaller the minimum installation room size in square meters (m²). This solution is cost-effective, but usually requires installation rooms that are too large to be implemented in practice. If the installation room is too small, it is advantageous to increase the outlet height with an extension such as a snorkel. 2. Refrigerant is pumped into the room by a fan: the height the medium reaches before it sinks again is the key factor here. The higher the refrigerant flows, the smaller the minimum installation room size in square meters (m²).In addition, a certain minimum volume flow must be achieved by the fan. All other device openings must not exceed 5 cm2 in total. However, the fan used for this is associated with costs, so it is dispensed with wherever possible, namely if it is not necessary due to the size of the installation room. 3. Refrigerant is extracted from the room to the outside using a fan. The only decisive factor here is the minimum volume flow. The other device openings must not exceed 5 cm2 in total. This variant also reduces the minimum installation room size to 0 m2, so that any installation location is suitable. However, this generally involves breaking through a wall, which is complex.

[0004] Currently, flammable refrigerants are therefore mainly used in outdoor heat pumps, or the refrigerant quantity is reduced so much that a leak cannot cause significant or health-related harm. For indoor heat pumps, the standard specifies three options for allowing the refrigerant to escape. Different heat pumps are therefore only suitable for specific installation locations, or more precisely, specific room sizes.

[0005] EP 3 705 799 A1 relates to a heat pump comprising a housing and a vent duct fluidically connected to the interior of the housing. In one embodiment, an inlet opening is provided on the vent duct, through which the installation room air can flow through an air duct to a mixing portal located upstream of the fan, from which a mixture of the installation room air and the engine room air is drawn toward the intake surface of the fan.

[0006] EP 3 578 895 A2 discloses a safety purge device for a refrigeration circuit housing. The housing has a purge air inlet for introducing purge air into the housing and a discharge line with a purge air outlet for removing the purge air from the housing. To generate the purge air flow, a purge air conveying fan is arranged in either the supply or discharge line.

[0007] WO 03 / 010473 A1 relates to a heat pump system with a closed housing equipped with a housing ventilation device for ventilating the housing interior. The ventilation device comprises two concentrically arranged tubes, with a fan arranged in the smaller of the two tubes for discharging air from the housing interior.

[0008] EP 3 719 416 A1 shows a heat pump which is installed in a housing outside a building, wherein an outlet opening is provided on the housing for refrigerant escaping inside the housing.

[0009] Against this background, the object of the present invention was to provide a heat pump that allows installation even in smaller spaces. Another object of the present invention was to provide an improved safety solution for indoor heat pumps that use flammable refrigerants. In any case, an alternative heat pump is to be provided.

[0010] According to the invention, a heat pump is proposed, in particular an indoor heat pump, with a refrigeration circuit with a flammable refrigerant, in particular R454C, and a housing in which the refrigeration circuit is arranged, wherein the housing has a venting duct with an outlet opening and a fan arranged in the venting duct, wherein the fan is designed to suck air from the interior of the housing out of the housing via the venting duct and the outlet opening in such a way that a negative pressure is maintained within the housing.

[0011] According to the invention, the fan is designed to additionally suck in air from outside the housing.

[0012] The fan then expels the drawn-in air back outside the housing via the ventilation duct. This creates circulation within the installation room. This circulation reduces the concentration of any escaping refrigerant in the room.

[0013] The invention therefore makes it possible to keep the refrigerant concentration in the installation room low, even in the event of a refrigerant leak. This is advantageous for flammable refrigerants, as it ensures that the refrigerant concentration in the installation room remains outside, particularly below, a critical range.

[0014] For example, the critical concentration for the refrigerant R454C is between 8% vol. and 12% vol., within which there is a risk of ignition.

[0015] According to the invention, the fan is also designed as a radial fan, wherein an intake surface of the radial fan is divided into two areas, each of which allows air to be drawn in from the inside of the housing or air from outside the housing.

[0016] For example, the fan can be installed horizontally at the top of the case, drawing in air from below, i.e., vertically. The radial fan then generates an airflow in a horizontal direction, i.e., perpendicular to the intake direction or surface.

[0017] The intake area can be chosen large enough to allow sufficient space for air to be sucked in both from inside the housing and from outside the housing.

[0018] Preferably, the heat pump has a mixing ventilation duct arranged between an inlet opening in the housing and the fan.

[0019] The mixing ventilation duct can therefore be mounted on the fan and convey air from the installation room, i.e., from outside the housing, to the fan. The inlet opening is designed as part of the housing and provides an opening between the installation room and the interior of the housing. Preferably, the inlet opening is completely sealed off from the mixing ventilation duct, so that no air enters through the inlet opening that is not conveyed by the mixing ventilation duct. In other words, the inlet opening does not represent an opening through which air can enter the interior of the housing.

[0020] Preferably, the inlet opening is arranged in a lower region of the housing, in particular in the lower 15% of the height of the housing.

[0021] The outlet opening is preferably located at the top of the housing, as explained in the introduction. By positioning the inlet opening far away from the outlet opening, optimized and particularly efficient mixing of the installation space is achieved.

[0022] Preferably, a distance between the outlet opening and the inlet opening is at least 50%, preferably at least 80% and particularly preferably at least 90% of the height of the housing.

[0023] The mixing ventilation duct is preferably designed as a corrugated hose or corrugated pipe.

[0024] A corrugated hose or pipe is flexible and therefore easy to install. Furthermore, the mixing ventilation duct is cost-effective and durable.

[0025] Preferably, the mixing ventilation duct can be hooked onto the fan and / or the inlet opening.

[0026] This allows for particularly simple installation. Preferably, a section, for example a sheet metal section, is designed to hold the fan and hook it into the mixing ventilation duct.

[0027] This allows the mixing ventilation duct, preferably the corrugated hose, to end directly at the intake surface of the fan and at the same time to reserve part of the intake surface for sucking in air from the interior of the housing.

[0028] Preferably, the fan is designed to be operated with a continuous power in the range of 0.5 W to 10 W, in particular between 1 W and 2 W.

[0029] This allows the negative pressure inside the housing to be maintained, sufficient mixing of the air in the installation location to be ensured at all times and, at the same time, energy consumption to be kept to a minimum.

[0030] Preferably, the heat pump further comprises a negative pressure determination unit, for example a pressure cell, which is designed to determine a negative pressure in the housing.

[0031] Preferably, the negative pressure determination unit is designed to generate an error signal if the negative pressure falls below a certain threshold. This error signal can, in particular, lead to the heat pump being shut down. Alternatively, the error signal for shutting down the heat pump can also be generated by a function monitoring system for the fan, for example, when a malfunction of the fan is detected.

[0032] Preferably, the housing is sealed with the exception of the outlet and inlet openings. Thus, no further openings are provided in the housing, whereby further openings are understood to mean, in particular, the openings of more than 5 cm2 required by the standard.

[0033] In any case, even with the low fan power of just a few watts, it is possible to achieve a negative pressure of, for example, 40 Pa in the case. If this value is significantly undershot, for example, the negative pressure is only 20 Pa, the error signal is triggered. These pressure values ​​are merely examples.

[0034] Preferably, one end of the vent duct has coupling means for connecting an external air duct.

[0035] This allows the air outlet to be moved further up in the room, which further improves the mixing of the installation location.

[0036] Preferably, the ventilation duct has sound insulation inside it.

[0037] The heat pump is preferably designed as an indoor brine heat pump.

[0038] Further advantages and features are described below with reference to the attached drawings. These show: Fig. 1 schematically and exemplarily a view of a heat pump according to the invention in cross section, Fig. 2 schematically and exemplarily a view of another heat pump according to the invention in cross section, Fig. 3 schematically and exemplarily a coupling in detail, Fig. 4 schematically and exemplarily a perspective view of a cover of the heat pump from above, Fig. 5 schematically and exemplarily a plan view of the view of the Fig. 4 from above, Fig. 6 schematic and exemplary view of the Fig. 4 with fan and Fig. 7 schematically and exemplarily the view of the Fig. 6 with cover.

[0039] Figur 1 shows a schematic and exemplary cross-sectional view of a heat pump 1 according to the invention. The heat pump 1 has a housing 10 with a front side 12, a rear side 14, a top side 16, and a bottom side 18. A cover 20 can usually be opened for servicing and configuring the heat pump 1 and allows access to the internal components.

[0040] The housing 10 shown as an example is divided into two parts with an upper housing section 102 and a lower housing section 104, which are separated by a separating layer 106.

[0041] In the upper housing section 102 of the two-part housing 10 is a Fig. 1 Refrigeration circuit 70 not shown further (cf. Fig. 2 ). This contains a flammable refrigerant, for example, R454C. For indoor heat pumps, it must therefore be ensured that there is no risk of fire at any time, even if a refrigerant leaks. Preferably, the upper housing section 102 is sealed from the lower housing section 104.

[0042] A storage tank 50, for example a hot water tank, is provided in the lower housing section 104 as a heat storage unit for the energy delivered by the refrigeration circuit. All connections between the refrigeration circuit and the storage tank 5 are known to those skilled in the art and have been omitted to simplify the illustration.

[0043] The present invention is based on the air flow from the interior of the housing 10 through a ventilation duct 30 to an outlet opening 17, which is effected by means of a fan 40 arranged in the ventilation duct 30.

[0044] The fan 40 is preferably operated continuously to maintain a negative pressure in the housing 10. If the negative pressure is not maintained, for example due to a leak in the housing 10, this can be used to shut down the heat pump 1. For this purpose, a pressure sensor (not shown) such as a pressure cell can be used.

[0045] The fan 40 is designed as a radial fan which sucks in air at an intake surface 42 on its underside and conveys it radially in the direction of the ventilation duct 30.

[0046] The intake surface 42 is divided into two parts and allows, on the one hand, the intake of air from the housing 10, but on the other hand, also the intake of air from outside the housing 10, ie from the installation room of the heat pump 1, via a mixing ventilation duct 60, which air enters the mixing ventilation duct 60 via an inlet opening 19.

[0047] In addition to generating the negative pressure in the housing 10, the fan 40 draws in air through the inlet opening 19 and expels the air through the outlet opening 17 back into the installation room or outside the housing 10, thus achieving a thorough mixing of the air outside the heat pump 1, i.e., in the installation room. This ensures that the concentration of refrigerant in the ambient air remains sufficiently low, even when refrigerant is escaping.

[0048] Fig. 2 shows schematically and by way of example a further cross-sectional view of a heat pump 1. The mixing ventilation duct 60 is divided into three parts in this example and comprises a flexible hose section 62, in particular a corrugated hose which is not foamed, a coupling section 64 and a fixed hose section 66, in particular a foamed corrugated hose.

[0049] Fig. 3 shows the coupling section 64 in detail. The coupling section 64 is designed as a double coupling with a fir-tree profile and can preferably be fixed in the separating layer 106. The fixed hose section 66 is mounted on the separating layer 106 before the lower housing section 104 is filled with foam, for example, for thermal insulation.

[0050] Fig. 4 shows a perspective view of the cover 20 with the vent duct 30 open. It can be seen that the vent duct 30 is labyrinth-like. This maximizes the airflow path and reduces the noise from the inside of the enclosure to the exit.

[0051] In Fig. 5 , which shows a top view of the Fig. 4 shown cover 20, the air flow direction in the ventilation duct 30 is shown by arrows 32.

[0052] The ventilation duct 30 ends at a location 36 adjacent to the outlet opening 17. A mounting device 34 for connecting the mixing ventilation duct 60 is formed in a mounting plate of the fan 40 in this example.

[0053] Fig. 6 shows the view of the Fig. 4 with mounted fan 40.

[0054] Fig. 7 shows the view of the Fig. 6 additionally with a cover 22 of the lid 20, which covers the ventilation channel 30.

Claims

1. A heat pump (1), in particular a heat pump (1) installed indoors, comprising - a refrigerant circuit with a flammable refrigerant, in particular R454C, and - a housing (10), in which the refrigerant circuit is arranged, wherein the housing (10) comprises a vent duct (30) with an outlet opening (17) and a fan (40) arranged in the vent duct (30), wherein the fan (40) is configured to suction air from the interior of the housing (10) via the vent duct (30) and the outlet opening (17) out of the housing (10) such that a vacuum is maintained inside the housing (10), and wherein the fan (40) is configured as a radial fan and is configured to additionally suction air from outside the housing (10), characterised in that the radial fan has a suction surface (42), which is divided into two areas which each suction air from the interior of the housing (10) or air from outside the housing (10).

2. The heat pump (1) according to any one of the preceding claims, further comprising a mixing ventilation duct (60), which is arranged between an inlet opening (19) into the housing (10) and the fan (40).

3. The heat pump (1) according to claim 2, wherein the inlet opening (19) is arranged in a lower region of the housing, in particular in the lower 15% of the height of the housing.

4. The heat pump (1) according to any one of claims 2 or 3, wherein a distance between the outlet opening (17) and inlet opening is at least 50%, preferably at least 80% and particularly preferably at least 90% of the height of the housing (10).

5. The heat pump (1) according to any one of claims 2 to 4, wherein the mixing ventilation duct (60) is in the form of a corrugated hose or corrugated pipe.

6. The heat pump (1) according to any one of claims 2 to 5, wherein the mixing ventilation duct (60) can be hooked onto the fan (40) and / or the inlet opening.

7. The heat pump (1) according to any one of the preceding claims, wherein the fan (40) is configured to be operated at a continuous power in the range of 0.5 W to 10 W, in particular between 1 W and 2 W.

8. The heat pump (1) according to any one of the preceding claims, further comprising a vacuum-determining unit, for example a pressure box, which is configured to determine a vacuum in the housing (10).

9. The heat pump (1) according to claim 8, wherein the vacuum-determining unit is further configured to generate an error signal in the event that the vacuum falls below a certain threshold.

10. The heat pump (1) according to any one of the preceding claims, wherein the housing (10) is sealed with the exception of the outlet opening (17) and the inlet opening (19).

11. The heat pump (1) according to any one of the preceding claims, wherein one end (34) of the vent duct (30) comprises coupling means for connecting an external air duct (50).

12. The heat pump (1) according to any one of the preceding claims, wherein the vent duct (30) comprises a sound insulation (38) in its interior.

13. The heat pump (1) according to any one of the preceding claims, wherein the heat pump (1) is in the form of a brine heat pump (1) installed indoors.