Electric heater for a vehicle

Abstract

An electric heater (1) for a vehicle, suitable for heating a liquid passing through the heater, comprises: - a body (2) made of die-cast metal material; - at least one resistor (3); - an inlet connector (12) protruding from the body (2) for liquid to enter the body (2); - an outlet connector (13) protruding from the body (2) for liquid to exit the body (2); - a first flow path (4) for the liquid, from the inlet connector (12) to the outlet connector (13), disposed on a first surface of the body (2); - a first cover (6) for closing the first flow path (4) with its first side; wherein the first flow path (4) includes at least one serpentine channel (21) starting at the inlet connector (12) and ending at the outlet connector (13); wherein the at least one serpentine channel... The serpentine channel (21) includes a first straight segment (35) near the inlet connector (12), a second straight segment (36) near the outlet connector (13), at least one third straight segment (37) between the first straight segment (35) and the second straight segment (36), and a plurality of hairpin bends (30), each hairpin bend (30) being arranged between a straight segment and the next straight segment; wherein the heating portion of the first resistor (3) is serpentine in shape and includes corresponding straight segments (50, 50') and bends (51), each bend (51) being arranged between the straight segments (50, 50') of the heating portion and the next straight segment; and wherein the straight segments (50, 50') of the heating portion are transverse to the straight segments (35, 36, 37) of the at least one serpentine channel (21).

Description

Technical Field

[0001] The present invention relates to an electric heater for vehicles, preferably but not necessarily for electric or hybrid vehicles, particularly for heating battery coolant in low outdoor temperatures to maintain a constant ideal operating temperature, or for heating liquid used in exchangers for heating air in passenger compartments. Background Technology

[0002] Batteries are essential for the operation of electric or hybrid vehicles. They must provide the energy required to run the vehicle quickly and reliably. Most batteries are high-voltage hybrid lithium-ion batteries and nickel-metal hydride batteries.

[0003] Operating within the specified temperature range is crucial for the batteries used. In fact, battery life begins to shorten from an operating temperature of +40°C, and performance and power decrease below -10°C. Furthermore, the temperature difference between individual battery cells must not exceed specified limits. Exceeding these limits accelerates aging and thus leads to premature battery failure. Vehicle manufacturers aim to make battery life comparable to the vehicle's lifespan. Therefore, the aging process can only be combated through optimized temperature management.

[0004] A battery cell includes individual cells, a cooling plate, and an auxiliary electric heater. The cooling plate is installed within the individual cell block and is circulated by a coolant (e.g., composed of water and ethylene glycol).

[0005] To ensure higher battery performance and maximum lifespan, the coolant temperature must be between approximately 15 and 30°C. When the temperature is too high, the liquid is cooled, for example, by a low-temperature radiator. Conversely, if the temperature is too low, the coolant is heated by an auxiliary electric heater. Therefore, the auxiliary electric heater ensures adequate control of the battery temperature even in low outdoor temperatures.

[0006] To perform this heating, the battery is integrated into the secondary circuit. This circuit ensures that the ideal operating temperature is kept constant between 15 and 30°C.

[0007] Such electric heaters typically include at least one electric heating unit for generating heat and dissipating the generated heat to a heat transfer medium (represented by the aforementioned liquid) through a body made of metallic material (in which the electric heating unit is in contact).

[0008] This liquid can be, for example, water, ethylene glycol, a mixture of water and ethylene glycol, or other suitable heat transfer liquids.

[0009] The liquid flows along a flow path comprising multiple parallel serpentine channels arranged on one side of the metal body and sealed by a cap fastened to the metal body. The channels communicate directly with the inlet and outlet sections of the heater at their ends.

[0010] The electric heater must be compact and is typically shaped as a rectangular parallelepiped. The diameters of the inlet and outlet ports or pipe connections are defined by the cross-section of the hydraulic circuit piping.

[0011] The electric heating unit includes heating elements, such as tubular resistors embedded in the thickness of the metal body or thin-film resistors deposited on the surface of the metal body that is not in contact with the liquid.

[0012] The electric heating unit is connected to an electronic control unit, which is able to control the heat power of the heating unit.

[0013] Disadvantageously, in known solutions, the tubular resistor is embedded in the thickness of the metal body and has a serpentine shape, which includes long straight segments that are substantially parallel to the long straight segments of the parallel-connected serpentine channels.

[0014] The hairpin bend of the tubular resistor connects the two subsequent straight segments of the tubular resistor.

[0015] The hairpin bend of the parallel-connected serpentine channel connects two subsequent straight segments of the channel.

[0016] This solution cannot avoid the formation of unwanted "hot spots" along the parallel-connected serpentine channels because the heat exchange between the metal heating element and the liquid is not optimal, and the temperature distribution along the flow path is uneven.

[0017] Therefore, an innovative electric heater is needed to overcome the above-mentioned shortcomings. Summary of the Invention

[0018] The purpose of this invention is to provide an electric heater for vehicles that can avoid the formation of unwanted "hot spots" in the liquid flow path inside the heater due to poor heat exchange between the metal heating element and the liquid.

[0019] Another object of the present invention is to provide an electric heater that enables optimal heat exchange between the metal heating element and the liquid to be heated, thereby preventing the metal element from overheating.

[0020] Another object of the present invention is to provide an electric heater that increases the center distance between the liquid inlet and outlet connectors so that more space is available for inserting an electrical connector.

[0021] The present invention achieves at least one of the above-mentioned objectives, as well as other objectives that will become apparent from this specification, through an electric heater for a vehicle, the electric heater being adapted to heat a liquid passing through the heater, comprising: - The main body is made of die-cast metal material; - At least one first resistor, which is at least partially coupled along a first plane of the body; - An inlet connector that protrudes from the body for liquid to enter the body; - An outlet connector, which protrudes from the body, for discharging liquid from the body; - A first flow path for the liquid, from the inlet connector to the outlet connector, is disposed on a first surface of the body; - A first cover, with its first side closing the first flow path; The first flow path includes at least one serpentine channel that starts at the inlet connector and ends at the outlet connector. The at least one serpentine channel includes a first straight segment near the inlet connector, a second straight segment near the outlet connector, and at least one third straight segment between the first straight segment and the second straight segment; Preferably, the first straight line segment, the second straight line segment, and the at least one third straight line segment are parallel to each other; The at least one serpentine channel is provided with a plurality of hairpin bends, each hairpin bend being arranged between a straight segment and the next straight segment of the at least one serpentine channel; The heating portion of the at least one first resistor includes a corresponding straight segment and at least one curved segment, the curved segment being arranged between the straight segment and the next straight segment of the heating portion; Furthermore, the straight segment of the heating section is arranged transversely to the straight segment of the at least one serpentine channel.

[0022] Further features and advantages of the invention will become more apparent from the detailed description of exemplary but non-limiting embodiments.

[0023] The dependent claims describe specific embodiments of the invention. Attached Figure Description

[0024] The description of the invention is referenced to the accompanying drawings, which are provided by way of non-limiting example, in which: Figure 1 A perspective view of an electric heater according to the present invention is shown; Figure 2 It shows Figure 1 Partial sectional perspective view of the electric heater; Figure 3 A first perspective view of a first embodiment of a component of an electric heater according to the present invention is shown; Figure 3a A second perspective view showing a first embodiment of the component partially cut along a first plane is shown; Figure 3b A third perspective view showing a first embodiment of the component, partially cut along a second plane; Figure 4 A top view of a second embodiment of the component is shown; Figure 5 A top view of a third embodiment of the component is shown; Figure 6 A top view of a fourth embodiment of the component is shown; Figure 7 A top view of a fifth embodiment of the component is shown; Figure 8 A top view of a sixth embodiment of the component is shown; Figure 9 It shows Figure 3 A fourth perspective view of the first embodiment of the component described herein, partially cut along a third plane; Figure 10 It shows Figure 3 A fifth perspective view of the first embodiment of the component described herein, partially cut along the fourth plane.

[0025] The same numbers and reference letters in the accompanying drawings represent the same elements or parts. Detailed Implementation

[0026] Referring to the accompanying drawings, some examples of electric heaters for vehicles (particularly electric or hybrid vehicles) are shown.

[0027] This type of electric heater can be used in particular to heat the battery coolant in electric or hybrid vehicles at low outdoor temperatures to maintain a constant ideal operating temperature, or to heat the liquid used in exchangers for heating the air inside passenger compartments.

[0028] In all embodiments of the present invention, the electric heater includes: - The main body 2 is made of die-cast metal material, preferably a single main body 2; - At least one first resistor 3, which is at least partially coupled along the first plane X of the body 2; - Inlet connector 12, which protrudes from the body 2, for liquid to enter the body 2; - Outlet connector 13, which protrudes from the body 2, for discharging liquid from the body 2; - A first flow path 4 for the liquid, which runs from the inlet connector 12 to the outlet connector 13, is provided on the first surface of the body 2; - The first cover 6, with its first side closing the first flow path 4 ( Figure 2 ).

[0029] The main body 2 may be a block made of die-cast metal material (such as aluminum or other suitable material) having a basically flat shape with two main dimensions (length and width), preferably at least twice the third dimension (thickness).

[0030] Advantageously, the first flow path 4 includes at least one serpentine channel 21, which begins at the inlet connector 12 and terminates at the outlet connector 13, and includes: - The first straight segment 35 near the inlet connector 12 - The second straight segment 36 near the outlet connector 13 - At least one third straight segment 37 located between the first straight segment 35 and the second straight segment 36. - Multiple hairpin-shaped bends 30, each hairpin-shaped bend 30 being arranged between one straight segment and the next straight segment of the at least one serpentine channel.

[0031] Preferably, but not necessarily, the first straight line segment 35, the second straight line segment 36, and the at least one third straight line segment 37 are parallel to each other.

[0032] Preferably, the hairpin-shaped bend 30 has a bend of 170-190°, more preferably 180°.

[0033] Advantageously, the heating portion of at least one first resistor 3 includes respective straight segments 50, 50' and at least one curved segment 51, the curved segment 51 being arranged between one straight segment and the next straight segment of the heating portion; and the straight segments 50, 50' of the heating portion are arranged transversely to the straight segments 35, 36, 37 of at least one serpentine channel 21 of the flow path 4.

[0034] This design can significantly reduce the formation of unwanted "hot spots" in the liquid flow path inside the heater due to poor heat exchange between the metal heating element and the liquid.

[0035] In a preferred variant of the heater of the present invention, the straight segments 50, 50' of the heating portion are arranged at an angle of 80° to 100° relative to the straight segments 35, 36, 37 of the at least one serpentine channel 21.

[0036] Preferably, the straight segments 50, 50' of the heating portion of at least one first resistor 3 are parallel to each other and arranged perpendicular to the first straight segment 35, the second straight segment 36, and at least one third straight segment 37 of the at least one serpentine channel 21 of the flow path 4. Therefore, the first straight segment 35, the second straight segment 36, and the at least one third straight segment 37 are also parallel to each other.

[0037] This scheme optimizes the heat exchange between the metal heating body 2 and the liquid to be heated, preventing overheating of the metal body and the formation of unwanted "hot spots" in the liquid flow path.

[0038] Preferably, at least one serpentine channel 21 includes at least two third straight segments 37, for example, only two ( Figures 7 to 8 More preferably at least three, for example four third line segments 37 ( Figure 3-6 The distance between the first straight segment 35 and the second straight segment 36 is between them. This increases the center distance between the liquid inlet connector 12 and the outlet connector 13, thus providing more space for the electrical connector 80 of the heater to be inserted.

[0039] In the first embodiment ( Figures 4 to 7 In the first resistor 3, only one first resistor 3 is provided, the heating part of which has a serpentine shape and includes corresponding straight segments 50, 50' and curved segments 51, each curved segment 51 being arranged between one straight segment and the next straight segment of the heating part.

[0040] In contrast, in the second embodiment of the present invention ( Figure 8 In the first plane X, at least two (e.g., only two) first resistors 3 are provided, which are arranged side by side on the first plane X, and their heating portions are U-shaped, so that each heating portion has only two straight segments 50 connected by a single bent segment 51.

[0041] In all embodiments of the invention, the number of hairpin bends 30 in at least one serpentine channel 21 is preferably, but not necessarily, odd.

[0042] In a preferred variant, the straight segment 50' of the heating portion of resistor 3 closest to the inlet connector 12 and the outlet connector 13 has a V-shaped bend 54 in the lateral end portion of the main body 2. This V-shaped bend is preferably located between the inlet connector 12 and the outlet connector 13. Figures 5 to 6 ).

[0043] This configuration allows for optimal heating of the liquid flow at at least one hairpin bend 30 in the lateral end portion of at least one serpentine channel 21 located in the body 2.

[0044] In the third embodiment of the present invention, a second resistor 3' is also provided. Figures 7 to 8 The first resistor 3' is at least partially joined along the first plane X of the body 2. The second resistor 3' has a corresponding U-shaped heating portion arranged outside the heating portion of the at least one first resistor 3.

[0045] exist Figure 7 In the variant shown, only one first serpentine resistor 3 is provided, and preferably, the heating portion of the first resistor 3 is approximately in the shape of a capital M.

[0046] In contrast, Figure 8 In the variant, two first resistors 3 are arranged side by side and their heating parts are U-shaped.

[0047] In a preferred variant, the U-shaped heating portion of the second resistor 3' includes two corresponding basic straight segments 60, 60' arranged transversely to the straight segments 35, 36, 37 of the at least one serpentine channel 21, and also includes another corresponding basic straight segment 61 arranged parallel to the straight segments 35, 36, 37 of the at least one serpentine channel 21.

[0048] In another preferred variant, the basic straight segment 60' closest to the inlet connector 12 and the outlet connector 13 is provided with a V-shaped bend 64 in the lateral end portion of the main body 2, which is preferably located between the inlet connector 12 and the outlet connector 13.

[0049] In all embodiments of the present invention, the inlet connector 12 and the outlet connector 13 can be arranged on the same side of the heater and substantially aligned with the first straight segment 35 and the second straight segment 36, respectively, for example as... Figures 1 to 5 and Figures 7 to 8 As shown. "Basic alignment" means arranged along the same longitudinal axis. In this case, the number of hairpin bends 30 is odd.

[0050] Or, such as Figure 6 As shown, the inlet connector 12 and the outlet connector 13 are arranged on opposite sides of the heater along the same longitudinal axis perpendicular to the first straight segment 35 and the second straight segment 36. In practice, in some vehicles, the battery's secondary heating circuit may not be prepared for adding an electric heater. In this case, a heater with the inlet and outlet on opposite sides may be convenient, as it can be integrated into the secondary circuit by disconnecting the pipe and connecting both ends of the pipe to opposite sides of the heater.

[0051] It is possible to provide an even number of hairpin bends 30, thereby arranging the inlet connector 12 and the outlet connector 13 on opposite sides of the heater.

[0052] In all embodiments of the invention, the inlet connector 12 and the first straight segment 35 can be connected via a first inclined portion 52, and the second straight segment 36 and the outlet connector 13 can be connected via a second inclined portion 53. The inclined portions reduce pressure loss because turbulence is reduced in the fluid transition section from the inlet connector 12 to the heated region of the flow path (located at one or more resistors) and from the heated region of the flow path to the outlet connector 13.

[0053] Preferably, the longitudinal extension length of the first inclined portion 52 and the second inclined portion 53 is approximately equal to or less than the radius of at least one hairpin-shaped bend 30 provided in the lateral end portion of the body 2.

[0054] For example, V-shaped bends 54 and 64 can be arranged in the section of the main body 2 that is surrounded between the first inclined portion 52 and the second inclined portion 53.

[0055] Figures 1 to 10 An embodiment of the heater of the present invention is shown, wherein the first surface of the main body 2 is arranged on the first side of the first plane X, and only one flow path 4 is provided.

[0056] The cover 6 preferably abuts against the compression area of ​​a corresponding sealing gasket located on the outer periphery of the first side of the body 2. Therefore, the cover 6 is a component separate from the heating body 2, for example, connected to the body 2 by screws and washers.

[0057] Alternatively, another embodiment of the heater of the present invention (not shown) further includes a second flow path for the liquid, extending from the inlet connector 12 to the outlet connector 13, the second flow path being disposed on a second surface of the body 2 arranged on a second side (opposite to the first side) of the first plane X. A second cover is provided, which closes the second flow path with one side thereof.

[0058] By providing these two flow paths on opposite sides of the main body 2, vehicle manufacturers can use the heater of the present invention in any orientation within a vehicle platform, as the heater will always have at least one side of the exchanger body with a heat exchange surface that facilitates the removal of air and / or vapor that may form at the solid / liquid interface. Furthermore, this enables more reliable operation under typical vehicle operating conditions, which involve the variability of the direction of gravity relative to the heater due to the longitudinal and lateral slope of the road, and inertial forces caused by braking or steering acceleration.

[0059] In a preferred variant, the first flow path 4 and the second flow path at least partially include an inlet connector 12 and an outlet connector 13. Specifically, the first flow path 4 and the second flow path 5 are each composed of a single channel 21 or each composed of at least two parallel serpentine channels.

[0060] Preferably, the first flow path and the second flow path are arranged symmetrically with respect to the first plane X, and may also be arranged symmetrically with respect to the second plane perpendicular to the first plane X.

[0061] Specifically, the first flow path and the second flow path are arranged symmetrically with respect to the first plane X; and each flow path is also symmetrical with respect to the second plane. Therefore, the first plane X of the body 2 is a plane of symmetry that includes at least a portion of the body 2 comprising the first and second flow paths. In fact, plane X divides the at least a portion of the body 2 into two parts, which correspond to each other in the planar symmetry of plane X. This construction of the liquid circuit inside the heater of the present invention allows vehicle manufacturers to use the heater of the present invention on all vehicle platforms and to freely and arbitrarily connect the inlet and outlet connections of the heater, freely reversing the flow direction.

[0062] The first plane X and the second plane can be the intermediate plane of the main body 2.

[0063] The inlet connector 12 and the outlet connector 13 can be arranged symmetrically with respect to the second plane.

[0064] In all embodiments of the heater of the present invention, at least one serpentine channel is only a single serpentine channel 21 ( Figures 3 to 10 Alternatively, it may include at least two parallel serpentine channels through which liquid flows in parallel (scheme not shown).

[0065] exist Figures 3 to 10 In the serpentine channel 21, each hairpin bend 30 connects two adjacent and substantially parallel straight segments of the channel 21. The shape of the channel 21 is also defined by longitudinal partitions 90, 91 disposed on the first surface of the body 2, which separate two consecutive straight segments of the channel 21.

[0066] Specifically, at least two longitudinal partitions 91 branch off from the side of the main body 2 where at least the inlet connector 12 is arranged; while at least one longitudinal partition 90 branch off from the side of the main body 2 opposite to the side where at least the inlet connector 12 is arranged.

[0067] Optionally, the longitudinal baffles 90, 91 and the resulting channel 21 have at least one corrugated portion to minimize turbulence in the liquid.

[0068] A gap can be provided between the end edges of the partitions 90 and 91 and the cover 6.

[0069] exist Figures 3 to 6 The device includes four third straight segments 37 and five hairpin bends 30. Therefore, it has two longitudinal partitions 90 and three longitudinal partitions 91.

[0070] exist Figures 7 to 8 The device includes two third straight segments 37 and three hairpin bends 30. Therefore, it includes one longitudinal partition 90 and two longitudinal partitions 91.

[0071] In a preferred variant, at least one curved guide vane 31, 31' is disposed in each hairpin bend 30 of the flow path for deflecting the liquid when the direction of liquid movement suddenly changes.

[0072] Preferably, at least two curved guide vanes 31, 31' (e.g., only two curved guide vanes) are provided in each hairpin bend 30.

[0073] These curved deflectors 31, 31' can be parallel to each other.

[0074] In a preferred variant, each curved deflector 31, 31' has a curved extension with a central angle of 80-190°, preferably 170-190° (e.g., 180°).

[0075] The presence of the curved guide vane reduces turbulence in the liquid flow in a single channel 21 within the hairpin bend, thereby reducing pressure loss. Despite the abrupt changes in direction in the flow path, these changes ensure the compactness of the heater.

[0076] In an example of the heater of the present invention, each curved guide plate 31, 31' is a curved baffle that preferably protrudes orthogonally from the first side of the body 2 to extend at least 50%, preferably at least 70%, more preferably at least 90% of the distance between the first cover 6 and the bottom of the channel 21, particularly the minimum distance between the first cover 6 and the bottom. In this variation, the curved guide plates also increase the heat exchange between the heating body 2 and the liquid.

[0077] For example, such curved baffles 31, 31' can be made by machining the first surface of the main body 2, or directly by die casting, forming a hollow area of ​​the main body 2, from which the curved baffles protrude.

[0078] Preferably, a gap is provided between the end edge of each curved partition 31, 31' and the first cover 6.

[0079] In the preferred variation, consider the feed direction A of the liquid in flow path 4 ( Figures 3a to 3bAt least one curved guide plate 31' in each hairpin bend 30 (preferably only the innermost curved guide plate relative to the body 2) is provided with a straight extension 34 extending from the corresponding hairpin bend 30.

[0080] Preferably, the length of the straight extension 34 is in the range of 0.5 to 1.5 times the curve radius defined by the curved guide plate 31'. This small straight extension can better guide the liquid flow from the innermost section of the corresponding hairpin bend, further reducing turbulence and thus reducing local pressure loss.

[0081] Preferably, the length of each straight segment 35, 36, 37 is at least twice the width of channel 21, which remains substantially constant along the flow path.

[0082] In the preferred variant, such as Figure 3a and Figures 9 to 10 As shown, multiple heat sinks 38 can be disposed in the first straight segment 35, the second straight segment 36 and at least one third intermediate straight segment 37.

[0083] Preferably, the heat sink 38 is in the form of fins, which are basically longitudinal fins that protrude from the first side of the body 2 to extend the distance between the first cover 6 and the bottom of the serpentine channel 21 by less than 50%, preferably less than 30%, more preferably less than 25%, particularly the minimum distance between the first cover 6 and the bottom.

[0084] The limited height of these heat sinks 38 increases the heat exchange surface area between the heating element 2 and the liquid, but the pressure loss is not significantly increased because the liquid flow remains essentially constant in the straight section of a single channel 21.

[0085] Preferably, the number of heat sinks 38 in each straight segment differs from the number of curved guide vanes 31, 31' in each hairpin bend 30. This difference in quantity increases the uniformity of liquid temperature because it prevents the formation of parallel and independent streamlines, such as preventing the formation of parallel channels, and promotes the remixing of the liquid between subsequent straight and curved segments.

[0086] By way of non-limiting example only, the number of heat sinks in each straight segment may be two or three, and the number of curved guide vanes in each hairpin bend may be one or two.

[0087] Furthermore, preferably, the heat sink 38 and the curved guide vanes 31, 31' are arranged discontinuously along a single channel 21 of the flow path 4, with spatial intervals between them. This alternating arrangement of the heat sink and the curved guide vanes, as well as the spaces between them, also increases the uniformity of the liquid temperature because it prevents the formation of parallel and independent streamlines and promotes the remixing of the fluid between successive straight and curved sections.

[0088] Another variation of the heater of the present invention includes: when at least one curved guide plate 31, 31' (e.g., only one curved guide plate) is provided with the aforementioned straight extension 34 extending from the hairpin-shaped bend 30, at least one longitudinal fin-shaped heat sink 38 is provided in the straight segment downstream of the hairpin-shaped bend 30, the heat sink having an end 39 bent toward the straight extension 34 (see...). Figures 9 to 10 (Example in the text). This design can further reduce any local pressure loss. For example, the curved end 39 can be provided in the second straight segment 36 and at least one third straight segment 37.

[0089] However, there is always a discontinuity between the heat sink 38 and the curved guide plates 31, 31'.

[0090] For example, refer to Figure 9 The fins 38 are at the same height relative to the bottom of the channel 21. It is not excluded that fins 38 may be provided at different heights. For example, if there are three fins 38, one fin may be higher than the other two. Therefore, the amount of aluminum used can be reduced, since only the fin closest to the resistor extension will be higher than the others.

[0091] The widths of fins 38 can also be equal or different. For example, refer to... Figure 9 There are three fins 38, one of which is wider than the other two. In this latter case, the amount of aluminum used can also be reduced.

[0092] Finally, the longitudinal extension lengths of the fins 38 (which are not necessarily parallel to each other) can also be equal or different.

[0093] Some fins 38 may also have some discontinuities along their longitudinal extension ( Figures 9 to 10 ).

[0094] Preferably, the fins 38 may be smooth or corrugated along the longitudinal side to locally induce slight turbulence and further enhance heat exchange between the heating body 2 and the liquid.

Claims

1. An electric heater (1) for a vehicle, suitable for heating a liquid passing through the heater, comprising: - The main body is made of die-cast metal material (2); - At least one first resistor (3) is coupled at least partially along the first plane (X) of the body (2); - Inlet connector (12), which protrudes from the body (2) for liquid to enter the body (2); - An outlet connector (13) protrudes from the body (2) for discharging liquid from the body (2); - A first flow path (4) for the liquid, which extends from the inlet connector (12) to the outlet connector (13), is disposed on the first surface of the body (2); - First cover (6), the first cover (6) closes the first flow path (4) with its first side; The heating portion of the at least one first resistor (3) includes a corresponding straight segment (50, 50') and at least one bent segment (51), the bent segment (51) being arranged between the straight segment (50, 50') and the next straight segment of the heating portion. Its features are, The first flow path (4) includes at least one serpentine channel (21) that starts at the inlet connector (12) and ends at the outlet connector (13). The at least one serpentine channel (21) includes a first straight segment (35) near the inlet connector (12), a second straight segment (36) near the outlet connector (13), and at least one third straight segment (37) between the first straight segment (35) and the second straight segment (36). The at least one serpentine channel (21) is provided with a plurality of hairpin bends (30), each hairpin bend (30) being arranged between a straight segment of the at least one serpentine channel and the next straight segment; Furthermore, the straight segments (50, 50') of the heating portion of the at least one first resistor (3) are arranged transversely to the straight segments (35, 36, 37) of the at least one serpentine channel (21).

2. The heater according to claim 1, wherein, The straight segments (50, 50') of the heating section are arranged at an angle of 80° to 100° relative to the straight segments (35, 36, 37) of the at least one serpentine channel (21).

3. The heater according to claim 1 or 2, wherein, The first straight segment (35), the second straight segment (36) and the at least one third straight segment (37) are parallel to each other; and preferably, the straight segments (50, 50') of the heating portion of the at least one first resistor (3) are parallel to each other and arranged perpendicular to the first straight segment (35), the second straight segment (36) and the at least one third straight segment (37) of the at least one serpentine channel (21).

4. The heater according to any one of the preceding claims, wherein, Only one first resistor (3) is provided, the heating part of which is serpentine and includes corresponding straight segments (50, 50') and curved segments (51), each curved segment (51) being arranged between the straight segments of the heating part and the next straight segment; Alternatively, at least two first resistors (3) are provided, which are arranged side by side on the first plane (X), and their heating portions are U-shaped, each heating portion having only two straight segments (50) connected by a single curved segment (51).

5. The heater according to any one of the preceding claims, wherein, The straight segment (50') closest to the inlet connector (12) and the outlet connector (13) in the heating section has a V-shaped bend (54) in the lateral end portion of the main body (2), and the V-shaped bend (54) is preferably located between the inlet connector (12) and the outlet connector (13).

6. The heater according to any one of claims 1 to 3, wherein, A second resistor (3') is provided, which is at least partially coupled along the first plane (X) of the body (2); Furthermore, the second resistor (3') has a corresponding U-shaped heating portion arranged outside the heating portion of the at least one first resistor (3).

7. The heater according to claim 6, wherein, Only one first resistor (3) is set, whose heating part is in a serpentine shape, preferably roughly in the shape of an uppercase M; Alternatively, at least two first resistors (3) may be provided, which are arranged side by side and whose heating portions are U-shaped.

8. The heater according to claim 6 or 7, wherein, The U-shaped heating portion of the second resistor (3') includes two corresponding basic straight segments (60, 60') arranged transverse to the straight segments (35, 36, 37) of the at least one serpentine channel (21), and also includes another corresponding basic straight segment (61) arranged parallel to the straight segments (35, 36, 37) of the at least one serpentine channel (21). Preferably, the basic straight segment (60') of the second resistor (3') closest to the inlet connector (12) and the outlet connector (13) is provided with a V-shaped bend (64) in the lateral end portion of the body (2), the V-shaped bend (64) preferably being located between the inlet connector (12) and the outlet connector (13).

9. The heater according to claim 5 or 8, wherein, The inlet connector (12) and outlet connector (13) are arranged on the same side of the heater and aligned with the first straight segment (35) and the second straight segment (36), respectively; or the inlet connector (12) and outlet connector (13) are arranged on opposite sides of the heater along the same longitudinal axis perpendicular to the first straight segment (35) and the second straight segment (36).

10. The heater according to claim 5, 8, or 9, wherein, The inlet connector (12) is connected to the first straight segment (35) via the first inclined portion (52); The second straight segment (36) is connected to the outlet connector (13) via the second inclined portion (53); Preferably, the longitudinal extension length of the first inclined portion (52) and the second inclined portion (53) is substantially equal to or less than the radius of at least one hairpin bend (30) provided in the lateral end portion of the body (2).

11. The heater according to any one of the preceding claims, wherein, The first surface of the main body (2) is arranged on the first side of the first plane (X); and wherein a second flow path for liquid is provided, the second flow path from the inlet connector (12) to the outlet connector (13), is provided on the second surface of the main body (2) arranged on the second side of the first plane (X), the second side being opposite to the first side; and wherein a second cover is provided, the second cover closing the second flow path with its first side; Preferably, the first flow path (4) and the second flow path, which at least partially include the inlet connector (12) and the outlet connector (13), are arranged symmetrically with respect to the first plane (X), and are also symmetrically arranged with respect to a second plane perpendicular to the first plane (X).

12. The heater according to any one of the preceding claims, wherein, The at least one serpentine channel is either a single serpentine channel (21) or includes at least two serpentine channels connected in parallel, through which liquid flows in parallel.

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