Electrical fluid-to-air heat exchanger for a vehicle and air conditioning unit with such an electrical fluid-to-air heat exchanger

Abstract

Electrical fluid-air heat exchanger (1) for a vehicle for heating a supply air flow (L) supplied into a vehicle interior, comprising - at least one louvre body (2.1) for transferring heat to the supply air flow (L) guided through the louvre body (2.1), - at least one fluid channel (3.1) thermally connected to the lamella body (2.1) and extending in a U-shaped manner in the vertical direction of the vehicle, with an inflow opening (3.10) and an outflow opening (3.11), - a hollow body (4) arranged in the vertical direction of the vehicle below the lamella body (2.1), which is fluidically connected to the inlet opening (3.10) and the outlet opening (3.11) of the at least one fluid channel (3.1) to form a closed fluid circuit (3) in such a way that fluid from the hollow body (4) can be fed to the inlet opening (3.10) and fluid from the outlet opening (3.11) can be returned to the hollow body (4), - an electric heating device (5) arranged below the hollow body (4) and thermally connected thereto for heating the fluid, - a compensating tank (4.1) for adjusting the amount of fluid circulating in the fluid circuit (3) to the respective temperature of the fluid, wherein the compensating tank (4.1) is fluidly connected to the hollow body (4), and - an electrical connection device (6) for supplying energy to the heating device (5).

Description

[0001] The invention relates to an electrical fluid-air heat exchanger for a vehicle and to an air conditioning unit for a vehicle with an electrical fluid-air heat exchanger according to the invention.

[0002] Heating systems for electric vehicles usually consist of either a high-voltage water heater, which must be connected to a coolant circuit via pumps, valves and vent lines, or a PTC air heater, which directly heats the supply air flow into the vehicle cabin.

[0003] Depending on the voltage level, the use of PTC air heaters can lead to high currents on the electric vehicle's voltage grid, which could place undesirable strain on both the voltage grid and the battery, and therefore a reduction in the usable range cannot be ruled out.

[0004] High voltage is defined as a voltage level of 400 V to 800 V.

[0005] DE 102 24 265 A1 discloses a fluid-to-air heat exchanger, to which fluid to be heated is supplied from a circulation system and then returned to the same. U-shaped fluid-carrying fluid channels extend between several parallel finned bodies, the ends of which terminate in a hollow body running perpendicular to the fluid channels. This hollow body is divided into two cavities perpendicular to the direction of the fluid channels, with fluid being supplied to a first cavity via an inlet and discharged via an outlet of a second cavity. The fluid from the first cavity is supplied to one end of the fluid channels and flows back into the second cavity from the other end.

[0006] In a first embodiment according to DE 102 24 265 A1, an electrical heating device with a control and / or regulating device is arranged between a finned body and a fluid channel of the fluid-air heat exchanger.

[0007] In a second embodiment according to DE 102 24 265 A1, the fluid to be heated collects in a further cavity below the fluid channels and the lamella bodies arranged between them, under which an electrical heating device is arranged.

[0008] DE 198 23 457 A1 describes a water-to-air heat exchanger of an air conditioning system with an integrated electric heating element, connected to an engine via a cooling water circuit. This water-to-air heat exchanger comprises two manifolds, between which fluid channels and finned bodies are arranged alternately, with some fluid channels being replaced by the electric heating elements.

[0009] According to DE 101 57 399 A1, a heater for a vehicle air conditioning system comprises a cylindrical base body with an electric heating element. Heat pipes are arranged in transverse openings in the base body, extending perpendicular to the longitudinal direction of the base body and connected by heat-emitting fins extending transversely thereto. The ends of the heat pipes are closed by a closure body. The heat generated by the electric heating element is distributed over the entire surface of the heater body via a fluid contained in the heat pipes. The heated fluid evaporates and rises as vapor in the heat pipes. This heats the supply air flow guided into the vehicle interior through the heat-emitting fins.

[0010] Furthermore, DE 10 2019 000 283 A1 discloses a cooling device with a cooling circuit to which at least one consumer is connected. During normal operation, the consumer receives a coolant from a storage tank by a submersible pump driven by a motor and returns the coolant to a heat exchanger connected to the storage tank on the outlet side. The cooling circuit is designed as a semi-closed cooling circuit in which the interior of the storage tank, which is otherwise sealed off from the atmosphere, can be connected to the atmosphere via a ventilation device. Pressure limit values ​​permitting ventilation of the storage tank are predetermined such that, during normal operation, no exchange takes place between the interior of the storage tank and the atmosphere.

[0011] A heat exchange system for heating an electric vehicle is known from DE 34 42 350 C2. It uses power semiconductors to control the traction motor, which dissipate heat during operation. The power semiconductors are thermally connected to a cooling circuit, which, in addition to a heater for the vehicle interior, also includes an expansion tank. The coolant in the cooling circuit is circulated by a pump.

[0012] DE 44 31 107 C1 describes a heat exchanger arrangement for heating the cabin of a vehicle, in which two manifolds of coolant pipes arranged vertically along the vehicle's perimeter are connected and run between the cooling fins. The two manifolds are provided with partition walls so that the coolant flows in opposite directions between adjacent coolant pipes, thus creating a U-shaped flow pattern.

[0013] Furthermore, DE 10 2017 100 019 A1 discloses a high-voltage liquid heater with an inlet and an outlet opening, comprising a liquid container, in whose interior a heating element is arranged. This heating element can be designed as a PTC heating element, in which the electrical resistance increases with increasing heating, thus automatically reducing the heating output.

[0014] WO 2006 / 077360 A1 discloses a radiator comprising an evaporation chamber as a first chamber and a second chamber, wherein the two chambers are connected via a network of heat pipes. These components form an evacuated and gas-tight system. During operation, fluid in the first chamber is heated by a heating element and thereby evaporated, so that the vapor rises via the heat pipes into the second chamber and, in this way, heat is released through condensation in the heat pipes and in the second chamber to the outside. This known radiator has an arrangement of two rows of heat pipes, such that one row is arranged on the front of the radiator and a second row on the back of the radiator.During operation, the fluid heated in the first chamber flows upward as vapor through both the heat pipes on the front and rear of the radiator toward the second chamber, and then flows back into the first chamber as a condensed liquid via both heat pipes. The heating element is located inside the first chamber, so that it is immersed in the fluid to be heated.

[0015] Finally, EP 0 462 154 B1 describes a vehicle heating system with a heating device operating by combustion of liquid fuel, comprising a combustion gas / liquid heat exchanger and a liquid / air heat exchanger for supplying heated vehicle heating air, which is fluidly connected to the combustion gas / liquid heat exchanger. The liquid / air heat exchanger and the heating device form a combined heating unit in which the liquid / air heat exchanger and at least the part of the heating device containing the combustion gas / liquid heat exchanger are combined. A pump is provided to circulate the liquid through the heating device and the liquid / air heat exchanger.

[0016] The object of the invention is to propose an electric fluid-to-air heat exchanger that can be operated independently, i.e., without the need for connection to a fluid circuit, e.g., an air conditioning system, and that enables effective heating of the supply air flow into the vehicle interior. Furthermore, a high power density is to be achieved within a small installation space. A further object is to provide an air conditioning unit with such a fluid-to-air heat exchanger.

[0017] The first-mentioned object is achieved by an electrical fluid-air heat exchanger having the features of patent claim 1.

[0018] Such an electrical fluid-air heat exchanger for a vehicle for heating a supply air flow supplied into a vehicle interior comprises: - at least one louvre body for transferring heat to the supply air flow guided through the louvre body, - at least one fluid channel thermally connected to the lamella body and extending in a U-shape in the vertical direction of the vehicle with an inflow opening and an outflow opening, - a hollow body arranged in the vertical direction of the vehicle below the lamella body, which is fluidically connected to the inlet opening and the outlet opening of the at least one fluid channel in order to form a closed fluid circuit in such a way that fluid from the hollow body can be fed to the inlet opening and fluid from the outlet opening can be returned to the hollow body, - an electric heating device arranged below the hollow body and thermally connected to it for heating the fluid, - a compensation tank for adjusting the amount of fluid circulating in the fluid circuit to the respective temperature of the fluid, wherein the compensation tank is fluidly connected to the hollow body, and - an electrical connection device for supplying power to the heating device.

[0019] This fluid-air heat exchanger according to the invention comprises a closed fluid circuit, so that it is not necessary to connect the fluid-air heat exchanger to a fluid circuit, for example an air conditioning system.

[0020] Since this fluid-to-air heat exchanger according to the invention requires a comparatively small amount of fluid as a heat transfer medium, e.g., water, rapid heating of the fluid and thus effective heating of the supply air flow for the vehicle interior is achieved. This effect is significantly supported by the direct connection of the electric heating device to the hollow body arranged below the fin body. Furthermore, the arrangement of the hollow body with the electric heating device below the fin body ensures a high flow rate through the fluid channel, thereby improving the power density.

[0021] According to an advantageous development of the invention, the electric fluid-to-air heat exchanger is equipped with a circulation pump arranged in the hollow body. This ensures a high power density, while at the same time, due to the low pressure losses of the closed fluid circuit, only a low energy requirement for the circulation pump is required.

[0022] The degree of integration of the electric fluid-to-air heat exchanger according to the invention is advantageously further increased by an electronic device for controlling the heating device. Control signals are preferably supplied to the electronic device via a control connection.

[0023] According to a further development, the circulation pump is designed as a centrifugal pump with at least one impeller, with the hollow body adapted to the diameter of the impeller at least in the vertical direction of the vehicle and perpendicular to the vertical direction of the vehicle. This ensures efficient circulation of the fluid in the closed fluid circuit.

[0024] Furthermore, the electrical heating device is advantageously designed as a high-voltage PTC resistance element with a supply voltage of 400 V to 800 V, whereby less high currents are generated.

[0025] The second object is achieved by an air conditioning device having the features of patent claim 7.

[0026] The electrical fluid-air heat exchanger according to the invention can be used advantageously in the form of a plug-and-play solution in an air conditioning unit of a vehicle's air conditioning system.

[0027] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. These show: Fig. 1 a schematic representation of an electrical fluid-air heat exchanger according to the invention in a front view, Fig. 2 a schematic representation of the electrical fluid-air heat exchanger according to Fig. 1 in a side view, and Fig. 3 a schematic representation of an air conditioning unit of a vehicle air conditioning system with an electric fluid-air heat exchanger according to the invention.

[0028] The electrical fluid-air heat exchanger 1 according to the invention intended for installation in a vehicle according to the Fig. 1 and Fig. 2 includes the following components: - A louvre body 2.1 and another louvre body 2.2, through which a supply air flow L supplied to a vehicle cabin is guided. The two louvre bodies 2.1 and 2.2 extend in the vertical direction of the vehicle (z-direction) and are arranged adjacent to each other. - Fluid channels 3.1, 3.2, and 3.3 extending in the vertical direction of the vehicle (z-direction), with fluid channel 3.2 located between the two lamella bodies 2.1 and 2.2 and thermally connected to them. Fluid channel 3.1 is located on the side of lamella body 2.1 facing away from lamella body 2.2 and is thermally connected to the same, while fluid channel 3.3 is located on the side of lamella body 2.2 facing away from lamella body 2.1 and is thermally connected to the same. - A hollow body 4 arranged in the vertical direction of the vehicle (z-direction) below the two lamella bodies 2.1 and 2.2, which extends in the transverse direction of the vehicle (y-direction) over the extent given by the fluid channel 3.1 and the fluid channel 3.3. - An expansion tank 4.1, which is connected to the hollow body 4 in the vehicle transverse direction (y-direction) and is fluidly connected to the same. - An electric heating device 5, which extends over the entire extent of the hollow body 4 in the vehicle's transverse direction (y-direction) and is arranged below the hollow body 4 in the vehicle's vertical direction (z-direction) and is thermally connected to the same. The electric heating device 5 is designed as a high-voltage PTC resistance element 5.0. - A circulation pump 7 designed as a centrifugal pump 7.0 and arranged in the hollow body 4, the rotational axis of which extends in the transverse direction of the vehicle (y-direction) over the entire length of the hollow body 4. A plurality of impellers 7.1 are arranged on the rotational axis of the centrifugal pump 7.0 over the length of the hollow body 4 in the transverse direction of the vehicle (y-direction). The inner cross-section of the hollow body 4 is according to Fig. 2 is adapted to the outer diameter of the impellers 7.1 of the centrifugal pump 7.0. For this purpose, the hollow body 4 has a rectangular cross-section, so that the side lengths of the rectangular shape each correspond to the diameter of an impeller 7.1. The hollow body 4 can also be designed with a circular cross-section, so that the inner diameter corresponds to the outer diameter of the impellers 7.1. - An electrical connection device 6 designed as a high-voltage connection 6.0, through which electrical energy is supplied to the high-voltage PTC resistance element 5.0. This high-voltage connection 6.0 is connected to a high-voltage vehicle electrical system, which in turn is supplied by a high-voltage battery. - An electronic device 8 which, depending on control signals, controls and / or regulates the power of the high-voltage PTC resistance element 5.0. - And a control terminal 9, to which the control signals for the electronic device 8 are fed. For example, this control terminal 9 is connected to a CAN bus, to which the control signals generated, for example, by an air conditioning control unit are applied.

[0029] The hollow body 4, together with the fluid channels 3.1, 3.2 and 3.3, forms a fluid circuit 3 in which a fluid flow, e.g. water or a glycol-water mixture, circulates as a heat transfer fluid.

[0030] The fluid channels 3.1, 3.2 and 3.3 have a U-shaped course and are fluidly connected to the hollow body 4 to form the fluid circuit 3. This structure is illustrated using the example of the fluid channel 3.1 using Fig. 2 explained.

[0031] The two legs of the U-shaped fluid channel 3.1 run in the vehicle's vertical direction (z-direction) and are directly mechanically connected to the adjacent lamella body 2.1 to form a thermal transition. The two openings 3.10 and 3.11 of the U-shaped fluid channel 3.1 are fluidly connected to the hollow body in such a way that the fluid from the hollow body 4 is fed to the inlet opening 3.10 and the fluid is returned to the hollow body 4 via the outlet opening 3.11. To actively maintain this circulation according to the arrows P1 and P2, the centrifugal pump 7.0 has the Fig. 2 shown direction of rotation D.

[0032] The fluid channels 3.2 and 3.3 are constructed accordingly and are also fluidly connected to the hollow body 4.

[0033] Thus, the fluid channel 3.1 as well as the fluid channels 3.2 and 3.3 together with the hollow body 4 form the fluid circuit 3.

[0034] If the fluid in the hollow body 4 is heated by the electrical heating element 5, the heated fluid rises in one leg of the fluid channels 3.1, 3.2, and 3.3 in the vertical direction of the vehicle (z-direction) according to the arrow P1 and then flows downward via the other leg of the fluid channels 3.1, 3.2, and 3.3 according to the arrow P2 back into the hollow body 4, where the fluid is heated again. During this circulation via the fluid channels 3.1, 3.2, and 3.3, the heated fluid transfers the heat to the louvre bodies 2.1 and 2.2, which heat the supply air flow L flowing through these louvre bodies 2.1 and 2.2.

[0035] The circulation pump 7, designed as a centrifugal pump 7.0, can also be dispensed with, since the fluid heated by the electric heating element 5 automatically creates circulation through the fluid channels 3.1, 3.2 and 3.3.

[0036] In order to allow the amount of fluid circulating in the fluid circuit 3 to adapt to the respective temperature of the fluid, the compensation tank 4.1 connected to the hollow body 4 is provided in order to compensate, for example, for an increase in the volume of the fluid at higher temperatures.

[0037] The fluid channels 3.1, 3.2, and 3.3 can be constructed mechanically in a simple manner. Starting with a hollow body 3.0 (see Fig. 2), which extends in the vehicle's vertical direction (z-direction), has a partition wall 3.12 in this direction, forming two cavities. The partition wall 3.12 is designed such that one end is connected to the hollow body 4, and the other end forms an opening with the hollow body 3.0, via which the two cavities are connected to form the U-shaped fluid channel 3.1, 3.2, and 3.3, respectively.

[0038] Fluid channels 3.1, 3.2 and 3.3 constructed in this way result in low manufacturing costs and thus in cost-effective production of the fluid-air heat exchanger 1.

[0039] To ensure a high degree of integration of the fluid-to-air heat exchanger 1, in addition to the high-voltage connection 6.0, the electronic device 8 and the control connection 9 are also integrated into the fluid-to-air heat exchanger 1. The control connection 9 is connected, for example, to a CAN bus, via which control signals are supplied to the electronic device 8. If, for example, a heating requirement is indicated by a control signal, the electronic device 8 controls the electric heating device 5 according to this control signal.

[0040] The one in the Fig. 1 and Fig. The fluid-air heat exchanger 1 shown in Figure 2 can also be constructed with more than two fin bodies and thus with correspondingly more than three fluid channels.

[0041] Finally, a conventional heating resistor can be used instead of the high-voltage PTC resistance element 5.0.

[0042] The Fig. 3 shows an air conditioning unit 10 of a refrigerant circuit (not shown) for a vehicle.

[0043] This air conditioning unit 10 comprises a housing 11 with a flow path 15 for cold and / or recirculated air and a flow path 16 for warm air, as well as air outlets 12, 13, and 14 into a vehicle interior. This air conditioning unit 10 further comprises an evaporator 20, a heating coil 21, and a fluid-to-air heat exchanger 1 according to the invention.

[0044] The evaporator 20 is connected to the refrigerant circuit (not shown) and serves to condition a supply air flow L1 supplied to the vehicle interior. This air flow is drawn into the housing 11 via a fan (not shown) and passed through the evaporator 20. The evaporator 20 transfers heat from the supply air flow L1 to the refrigerant flowing through the evaporator 20. The supply air flow L1 is thereby cooled and / or dehumidified.

[0045] The supply air flow L1 exiting from the evaporator 20 can, depending on the position of the air flaps 18 and 19, be guided through the flow path 15 and the flow path 16 as a partial air flow to the mixing chamber 17.

[0046] The supply air flow L1 is divided depending on the position of the air flaps 18 and 19 or is fed entirely to one of the flow paths 15 or 16.

[0047] The heating register 21 and the fluid-air heat exchanger 1 according to the invention are arranged within the flow path 16 for warm air, through which a supply air flow L, for example as a partial air flow of the supply air flow L1, flows in the listed order.

[0048] The heating register 21 serves as a heat sink, which transfers heat to the supply air flow L, for example by means of a heat pump function of the refrigerant circuit, wherein the vehicle ambient air and / or a heat-generating component of the vehicle serves as the heat source.

[0049] If additional heat is required that cannot be provided by the available heat sources, the fluid-to-air heat exchanger 1 according to the invention is operated, with which the fluid circulating in the fluid circuit 3 is heated by electrical heating by means of the electric heating device 5. The heat of the fluid is transferred to the supply air flow L by means of the fin bodies 2.1 and 2.2.

[0050] The two flow paths 15 and 16 each open into the mixing chamber 17, so that the partial air flows divided between the two flow paths 15 and 16 are mixed in the mixing chamber 17 and then divided as conditioned supply air flow L1 to the air outlets 12, 13 and 14 depending on the position of the air flaps 12.1, 13.1 and 14.1 and introduced into the vehicle interior.

[0051] In summary, the fluid-air heat exchanger 1 according to the invention has Fig. 1 and Fig. 2 following advantages: - Due to the autonomous operation of the fluid-air heat exchanger according to the invention, the valves usually required for switching a heat exchanger integrated into a refrigerant circuit on or off are no longer required. - In comparison to a heating circuit of a heat exchanger integrated into a refrigerant circuit, the air flow to be heated is heated very quickly by means of the fluid-air heat exchanger according to the invention. - Since the circulation pump is integrated in the fluid-air heat exchanger according to the invention, the piping which is usually required in a heating circuit according to the state of the art is no longer necessary. - The high integration density of the components of the fluid-air heat exchanger according to the invention results in a low installation space requirement. - The fluid-air heat exchanger according to the invention enables easy replacement with high-voltage air heaters. - Venting of the fluid-air heat exchanger according to the invention is not necessary, so there is no risk of “heating gurgling”. - And the structure of the fluid circuit of the fluid-air heat exchanger according to the invention ensures low pressure losses in the fluid circuit and thus leads to a low energy requirement of the circulation pump. REFERENCE SYMBOL 1 electric fluid-air heat exchanger 2.1 Lamellar body 2.2 Lamellar body 3 Fluid circuit 3.0 Hollow body 3.1 Fluid channel 3.10 Inlet opening of the fluid channel 3.1 3.11 Outlet opening of the fluid channel 3.1 3.12 Partition wall 3.2 Fluid channel 3.3 Fluid channel 4 hollow bodies 4.1 Expansion tank 5 electric heating device 5.0 High-voltage PTC resistance element 6 electrical connection device 6.0 High-voltage connection 7 Circulation pump 7.0 Centrifugal pump 7.1 Impeller of the centrifugal pump 7.0 7.2 Axis of rotation 8 Electronic equipment 9 Control connection 10 air conditioner 11 Air conditioner housing 10 12 Air outlet vehicle interior 12.1 Air flap for air outlet 12 13 Air outlet vehicle interior 13.1 Air flap for air outlet 13 14 Air outlet vehicle interior 14.1 Air flap for air outlet 14 15 Flow path for cold and / or recirculating air 16 Flow path for warm air 17 Mixing room 18 Air flap 19 Air flap 20 evaporators 21 heating registers D Direction of rotation L Supply air flow L1 supply air flow P1 Arrow P2 Arrow

Claims

[1] Electrical fluid-air heat exchanger (1) for a vehicle for heating a supply air flow (L) supplied into a vehicle interior, comprising - at least one louvre body (2.1) for transferring heat to the supply air flow (L) guided through the louvre body (2.1), - at least one fluid channel (3.1) thermally connected to the lamella body (2.1) and extending in a U-shaped manner in the vertical direction of the vehicle, with an inflow opening (3.10) and an outflow opening (3.11), - a hollow body (4) arranged in the vertical direction of the vehicle below the lamella body (2.1), which is fluidically connected to the inlet opening (3.10) and the outlet opening (3.11) of the at least one fluid channel (3.1) to form a closed fluid circuit (3) in such a way that fluid from the hollow body (4) can be fed to the inlet opening (3.10) and fluid from the outlet opening (3.11) can be returned to the hollow body (4), - an electric heating device (5) arranged below the hollow body (4) and thermally connected thereto for heating the fluid, - a compensating tank (4.1) for adjusting the amount of fluid circulating in the fluid circuit (3) to the respective temperature of the fluid, wherein the compensating tank (4.1) is fluidly connected to the hollow body (4), and - an electrical connection device (6) for supplying energy to the heating device (5). [2] Electrical fluid-air heat exchanger (1) according to claim 1 with a circulation pump (7) arranged in the hollow body (4). [3] Electrical fluid-air heat exchanger (1) according to claim 1 or 2 with an electronic device (8) for controlling the heating device (5). [4] Electrical fluid-air heat exchanger (1) according to claim 3 with a control connection (9) for supplying control signals to the electronic device (8). [5] Electric fluid-air heat exchanger (1) according to one of claims 2 to 4, in which the circulation pump (7) is designed as a centrifugal pump with at least one impeller (7.1), wherein the hollow body (4) is adapted to the diameter of the impeller (7.1) at least in the vehicle vertical direction and perpendicular to the vehicle vertical direction. [6] Electrical fluid-air heat exchanger (1) according to one of the preceding claims, in which the electrical heating device (5) is designed as a high-voltage PTC resistance element (5.0) with a supply voltage of 400 V to 600 V. [7] Air conditioning unit (10) for a vehicle with an electric fluid-air heat exchanger (1) according to one of the preceding claims.

Images