A grouped air-heating PTC heater

Abstract

The present invention discloses a grouped air-heating PTC heater. By designing the self-structure and arrangement form of two positive connection bars, the two positive connection bars not only have the function of arbitrarily grouping the PCB circuit board, but also have the advantages of simple and reliable structure and low cost. Also, based on the above design of the self-structure and arrangement form of the two positive connection bars, all heating bars are divided into two heating groups, and all heating bars in each heating group are symmetrically distributed about the center of the heating core in the stacking direction, so that the positions of all heating bars included in each heating group on the heat dissipation surface of the heating core are relatively dispersed, thereby effectively solving the technical problem of uneven air outlet temperature existing in the air-heating PTC heater that realizes grouping through connection bars at present.

Description

Technical Field

[0001] The present invention belongs to the technical field of air heating in new energy vehicles, and particularly relates to a grouped air heating PTC heater. Background Art

[0002] With the increasing emphasis on environmental protection and the consumption of non-renewable energy, the number of new energy vehicles has increased explosively in recent years. However, since new energy vehicles do not have an internal combustion engine as a power device for generating heat sources, new energy vehicles must rely on electric heaters to provide heat sources for functions such as defrosting and warm air in the vehicle; the heating elements used in heaters include electric heating wires, electric heating tubes, and PTC (Positive Temperature Coefficient), etc. PTC is applied in new energy vehicles due to its advantages such as large power density, wide operating voltage range, and good withstand voltage reliability.

[0003] Currently, the air heating PTC heaters used in new energy vehicles generally adopt a waterproof PTC air heater for electric vehicles disclosed in Chinese Patent CN208947030U. See Figure 1 As shown, the heating core 1 of the air heating PTC heater includes a plurality of heat dissipation strips 2 and heating strips 3. See Figure 2 and Figure 8 As shown, the heat dissipation strip includes a rectangular aluminum frame 4 surrounded by an aluminum plate. The aluminum frame is provided with heat dissipation fins 5 that extend in a zigzag manner along the length direction of the aluminum frame. A plurality of curved surfaces 6 formed by the zigzag extension of the heat dissipation fins are in contact with the side walls in the width direction of the aluminum frame; see Figure 3 and Figure 7 As shown, the heating strip includes an aluminum tube 7 with a rectangular cross-section. The aluminum tube is provided with two electrode strips 8 that are parallel and facing each other and extend along the length direction of the aluminum tube. The electrode strips are parallel to the side walls where the long sides are located in the cross-section of the aluminum tube. A plurality of PTC heating sheets 9 are arranged along the length direction between the two electrode strips. The PTC heating sheets are attached to the two side electrode strips. A layer of insulating paper 10 is wrapped outside the two electrode strips and the plurality of PTC heating sheets to isolate them from the aluminum tube. Insulating end plates are provided at both ends of the aluminum tube. The same ends of the two electrode strips have extension parts that extend out of the insulating end plates along the length direction of the aluminum tube. The two extension parts are respectively used as the positive terminal 12 and negative terminal 13 of the electrode strip; see Figure 1 As shown, the plurality of heat dissipation strips 2 and heating strips 3 are alternately stacked. The side walls where the long sides are located in the cross-section of the aluminum tube are in contact with the side walls in the width direction of the adjacent aluminum frame so that the heating strip can transfer heat to the heat dissipation strip. The length, width, and thickness directions of the heating core are the same as those of the aluminum frame. The two surfaces in the thickness direction of the heating core are heat dissipation surfaces. All the positive terminals and negative terminals are located at the same end of the heating core and all the positive terminals and negative terminals are respectively located on two planes in the thickness direction of the heating core for installation and connection.

[0004] To meet different heating requirements, the air-heating PTC heater needs to have a power adjustment function. Generally, the air-heating PTC heater is divided into three power levels: low, medium, and high. That is, all heating bars are divided into two heating groups with different numbers of heating bars according to power. When only the heating group with fewer heating bars works, it is in the low gear; when only the heating group with more heating bars works, it is in the medium gear; and when both heating groups work, it is in the high gear. The main ways of power adjustment are PWM adjustment and group adjustment. Considering product cost, new energy vehicles generally use air-heating PTC heaters with group adjustment. Since the power of the vehicle air-heating PTC heater is relatively high and it includes a large number of heating bars, if the positive and negative ends of each heating bar are directly connected by wires and combined with circuit control to achieve group adjustment, not only is the connection cumbersome, but also it occupies a large space. If sockets corresponding to the positive and negative ends of each heating bar are designed, not only is the reliability of the connection between the positive and negative ends and the socket poor under the vibration of the vehicle during driving, but also the manufacturing cost is relatively high. Therefore, currently, group adjustment is generally achieved by connecting the positive and negative ends of the heating bars through connection bars or PCB circuit boards to reduce the manufacturing cost, improve the connection reliability, and at the same time reduce the volume of the air-heating PTC heater for easy installation. Among them, PCB circuit board grouping means connecting the positive ends of each heating bar through the PCB circuit board, and designing an interspersed or symmetric grouping method through a double-layer PCB circuit board so that all heating bars in each heating group are evenly distributed on the heat dissipation surface of the heating core, thereby ensuring the uniform air outlet temperature of the air-heating PTC heater. However, the cost of using a PCB circuit board is relatively high, and since the power of the vehicle air-heating PTC heater is relatively large, the copper electrode lines on the PCB circuit board need to be thickened by special processes, which will further increase the cost of the air-heating PTC heater using a PCB circuit board for grouping. For example, the electrode lead-out device of the insulated PTC heater disclosed in Chinese Patent CN206650857U, see Figure 4 As shown, group adjustment by connection bars means connecting the negative ends 13 of all heating bars 3 together to a negative connection bar 14, and separately providing two positive connection bars 15 corresponding to the two heating groups one by one. The positive connection bars are connected to the positive ends 12 of the heating bars in the corresponding heating group. However, since the positive ends of all heating bars are located on the same plane, therefore, the positions of all heating bars included in each heating group need to be continuous for connection to the corresponding positive connection bar, that is, all heating bars included in each heating group are concentrated at one place on the heat dissipation surface of the heating core, which is uneven. This results in uneven air outlet temperature of the air-heating PTC heater when the two heating groups are started separately, which not only affects the user experience, but also affects the heating efficiency of the air-heating PTC heater for the car body. Summary of the Invention

[0005] Aiming at the above deficiencies of the prior art, the purpose of the present invention is to provide a grouped air-heating PTC heater, which solves the technical problem of uneven air outlet temperature in the air-heating PTC heater grouped by connection bars, and achieves the effects of improving the user experience and reducing costs.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A grouped air-heating PTC heater includes a heating core body. The heating core body includes a plurality of heat dissipation bars and heating bars alternately stacked along its width direction. The positive and negative end heads of all heating bars are located at the same end of the heating core body. All positive end heads and all negative end heads are respectively located on both sides in the thickness direction of the heating core body. At the end of the heating core body where the positive and negative end heads are located, a negative connection bar and a positive connection bar are provided. Both the negative connection bar and the positive connection bar extend along the width direction of the heating core body. The negative connection bar is connected to all negative end heads. All heating bars are divided into two heating groups with unequal numbers of heating bars. In each heating group, all heating bars are symmetrically distributed around the center in the width direction of the heating core body. The number of positive connection bars is two, and the two positive connection bars correspond to the two heating groups one by one. Protrusions are formed on the positive connection bars, and there are a plurality of connection parts respectively facing the positive end heads in the corresponding heating groups, and the connection parts are connected to the positive end heads one by one.

[0008] Further, the positive end heads in the two heating groups alternate at least three times in the width direction of the heating core body.

[0009] Further, the two positive connection bars are located in the same plane in the length direction of the heating core body. The two positive connection bars are respectively located on both sides of all positive end heads in the thickness direction of the heating core body. At the end of the heating core body where the positive and negative end heads are located, an insulating fixing plate is provided. The insulating fixing plate has two through accommodating grooves, and the two accommodating grooves respectively match the two positive connection bars. The two positive connection bars are respectively fixed in the corresponding accommodating grooves.

[0010] Further, there is a distance between the positive connection bar and the negative connection bar in the length direction of the heating core body.

[0011] Further, the distance between the heating core body and the positive connection bar is greater than the distance between the heating core body and the negative connection bar. Both ends of the negative connection bar are bent and extend away from the heating core body and are fixedly connected to the insulating fixing plate.

[0012] Further, wires are welded on the negative connection bar and the two positive connection bars.

[0013] Further, the heating strip includes an aluminum tube with a rectangular cross-section. Inside the aluminum tube, there are two electrode strips that are parallel, facing each other, and extend along the length direction of the aluminum tube. The electrode strips are parallel to the side wall where the long side of the aluminum tube cross-section is located. The same ends of the two electrode strips have extension parts that extend out of the aluminum tube along the length direction of the aluminum tube and form the positive terminal head and the negative terminal head. Both short sides of the aluminum tube cross-section are V-shaped with the openings facing outside the aluminum tube, and the short sides of the aluminum tube cross-section are transitioned through an inward concave arc section in the middle of the V shape.

[0014] Further, the wall thickness of the side wall where the long side of the aluminum tube cross-section is located is 0.6 - 0.8 mm.

[0015] Further, the heat dissipation strip includes a rectangular aluminum frame formed by aluminum plates. In the aluminum frame, there are heat dissipation fins that extend in a zigzag manner along the length direction of the aluminum frame. A number of curved surfaces formed due to the zigzag extension of the heat dissipation fins are in contact with the side walls in the width direction of the aluminum frame. A number of inclined surfaces formed due to the zigzag extension of the heat dissipation fins and distributed at intervals along the length direction of the aluminum frame each have a plurality of window structures. The window structure includes a square hole that penetrates through the inclined surface. Inside the square hole, a plurality of long strip-shaped blades are arranged in parallel at intervals. The blades are arranged along the extension direction of the heat dissipation fins, and the blades have an angle with the inclined surface where they are located. The two ends of the blades are fixedly connected to the inner wall of the square hole.

[0016] Further, 3 long strip-shaped blades are arranged in parallel at intervals inside the square hole. The plurality of window structures on each inclined surface are distributed at intervals along the thickness direction of the aluminum frame, and the angle between the blade and the inclined surface where it is located is 25 - 35°.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. By designing the self-structure and arrangement form of the two positive connection strips, the two positive connection strips not only have the function equivalent to any grouping of the PCB circuit board, but also have the advantages of simple and reliable structure and low cost. Also, based on the above design of the self-structure and arrangement form of the two positive connection strips, all the heating strips are divided into two heating groups, and all the heating strips in each heating group are symmetrically distributed about the center in the stacking direction with respect to the heating core body, so that the positions of all the heating strips included in each heating group on the heat dissipation surface of the heating core body are relatively dispersed and uniform, thus effectively solving the technical problem of uneven air outlet temperature existing in the air-heating PTC heater that realizes grouping through connection strips at present.

[0019] 2. By providing the insulating fixing plate, not only can the positions of the two positive connection strips be well restricted to avoid contact between the two connection strips due to the vibration during vehicle driving, but also by separating the two positive connection strips through the insulating fixing plate, the insulation performance between the two positive connection strips can be further improved, making the air-heating PTC heater have better reliability.

[0020] 3. In the grouped air-heating PTC heater of the present invention, the structures of the aluminum tube and the heat dissipation fins are respectively improved, the heat dissipation performance of the heat dissipation fins is enhanced, and while reducing the wall thickness of the side wall where the long side is located in the cross-section of the aluminum tube, the structural strength during the rolling process of the aluminum tube is ensured, thereby reducing the contact resistance between the PTC heating sheet and the electrode strip and the thermal resistance among the electrode strip, the PTC heating sheet and the aluminum tube, and improving the heating efficiency and service life of the air-heating PTC heater. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 FIG. is a three-dimensional schematic diagram in which the heat dissipation strips and the heating strips are alternately stacked;

[0022] Figure 2 FIG. is a three-dimensional schematic diagram of the heat dissipation strip;

[0023] Figure 3 FIG. is a three-dimensional schematic diagram of the heating strip;

[0024] Figure 4 FIG. is a three-dimensional schematic diagram of the heating core body grouped through a connector as described in the background art;

[0025] Figure 5 FIG. is a three-dimensional schematic diagram of the heating core body according to the embodiment;

[0026] Figure 6 For Figure 5 front view of;

[0027] Figure 7 For Figure 3 cross-sectional view taken along line A-A in;

[0028] Figure 8 For Figure 2 enlarged top view at B in;

[0029] Figure 9 For Figure 8 cross-sectional view taken along line C-C in;

[0030] Figure 10 FIG. is a structural diagram of the positive connection strip in the air-heating PTC heater with four power levels according to the embodiment;

[0031] Wherein, the heating core body 1, the heat dissipation strip 2, the heating strip 3, the aluminum frame 4, the heat dissipation fin 5, the curved surface 6, the aluminum tube 7, the electrode strip 8, the PTC heating sheet 9, the insulating paper 10, the insulating end plate 11, the positive terminal 12, the negative terminal 13, the negative connection strip 14, the positive connection strip 15, the connection part 16, the insulating fixing plate 17, the negative fixing plate 18, the arc section 19, the inclined surface 20, the square hole 21, the blade 22, the wire 23. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the detailed description of the embodiments of the present invention provided in the drawings below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings. In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the invention is normally placed. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance. In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but may be slightly inclined. In the description of the present invention, it should also be noted that unless otherwise clearly defined and limited, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Embodiment:

[0035] Please refer to Figure 1 As shown, a grouped air-heating PTC heater includes a heating core 1, and the heating core 1 includes a plurality of heat dissipation strips 2 and heating strips 3; Please refer to Figure 2 and Figure 8As shown, the heat dissipation strip 2 includes a rectangular aluminum frame 4 formed by an aluminum plate. In the aluminum frame 4, there are heat dissipation fins 5 that extend in a zigzag manner along the length direction of the aluminum frame 4. A number of curved surfaces 6 formed due to the zigzag extension on the heat dissipation fins 5 are in contact with the side walls in the width direction of the aluminum frame 4; please refer to Figure 3 and Figure 7 As shown, the heating strip 3 includes an aluminum tube 7 with a rectangular cross-section. Inside the aluminum tube 7, there are two electrode strips 8 that are parallel and facing each other and extend along the length direction of the aluminum tube 7. The electrode strips 8 are parallel to the side walls where the long sides are located in the cross-section of the aluminum tube 7. Along the length direction of the aluminum tube 7 between the two electrode strips 8, there are a number of PTC heating sheets 9. The PTC heating sheet 9 is a heating sheet made of PTC material. The PTC material is a semiconductor ceramic material based on BaTiO3. The PTC heating sheet 9 is in contact with the two side electrode strips 8. A layer of insulating paper 10 is wrapped outside the two electrode strips 8 and the number of PTC heating sheets 9 to isolate them from the aluminum tube 7. Insulating end plates 11 are provided at both ends of the aluminum tube 7. The same ends of the two electrode strips 8 have extension parts that extend out of the insulating end plates 11 along the length direction of the aluminum tube 7. The two extension parts are respectively used as the positive terminal 12 and the negative terminal 13 of the electrode strip 8; refer to Figure 1 、 Figure 2 and Figure 3 As shown, the number of heat dissipation strips 2 and heating strips 3 are alternately stacked. The side walls where the long sides are located in the cross-section of the aluminum tube 7 are in contact with the side walls in the width direction of the adjacent aluminum frame 4 so that the heating strip can transfer heat to the heat dissipation strip. The length, width, and thickness directions of the heating core are the same as those of the aluminum frame. The two sides in the thickness direction of the heating core are heat dissipation surfaces. All the positive terminals 12 and negative terminals 13 are located at the same end of the heating core and all the positive terminals and negative terminals are respectively located on the two planes in the thickness direction of the heating core for easy installation and connection.

[0036] Please refer to Figure 5 and Figure 6 As shown, at one end of the heating core 1 where the positive terminal 12 and the negative terminal 13 are located, there are a negative connection strip 14 and a positive connection strip 15. The negative connection strip 14 and the positive connection strip 15 both extend along the stacking direction. The negative connection strip 14 is connected to all the negative terminals 13. All the heating strips 3 are divided into two heating groups with unequal numbers of heating strips 3; in each heating group, all the heating strips 3 are symmetrically distributed about the center of the heating core 1 in the stacking direction. The number of positive connection strips 15 is two. The two positive connection strips 15 are located on the same plane in the length direction of the heating strip 3. The two positive connection strips 15 are respectively located on both sides of all the positive terminals 12 in the thickness direction of the heating core 1. The two positive connection strips 15 correspond to the two heating groups one by one. On the positive connection strip 15, there are a number of connection parts 16 that protrude and face the positive terminals 12 in the corresponding heating group. The number of connection parts 16 is in one-to-one correspondence with the positive terminals 12 in the corresponding heating group and are connected to each other.

[0037] In the grouped air-heating PTC heater of the present invention, positive electrode connection bars 15 extending along the stacking direction are respectively arranged on both sides of all positive electrode terminals 12 to separate the two positive electrode connection bars 15 to avoid mutual discharge. The two positive electrode connection bars 15 respectively correspond to two heating groups. Multiple connection parts 16 protruding towards multiple positive electrode terminals 12 in the corresponding heating group are formed on the positive electrode connection bars 15, and the multiple connection parts 16 are connected to the multiple positive electrode terminals 12 in the corresponding heating group one by one. By designing the self-structure and arrangement form of the two positive electrode connection bars 15, the present invention enables the two positive electrode connection bars 15 to have the function of arbitrarily grouping the PCB circuit board, and also has the advantages of simple and reliable structure and low cost. In addition, when stamping the positive electrode connection bars 15, the current-carrying area can be increased by increasing their thickness, thus avoiding the problem that the copper electrode lines need special processes to be thickened when grouping through the PCB circuit board. Based on the above design of the self-structure and arrangement form of the two positive electrode connection bars 15, the present invention divides all heating bars 3 into two heating groups, and all heating bars 3 in each heating group are symmetrically distributed about the center of the heating core 1 in the stacking direction, so that the positions of all heating bars 3 included in each heating group on the heat dissipation surface of the heating core 1 are relatively scattered, thereby effectively solving the technical problem of uneven air outlet temperature existing in the air-heating PTC heater grouped by connection bars at present.

[0038] In this embodiment, the positive electrode terminals 12 in the two heating groups alternate at least three times in the stacking direction; to further improve the dispersion degree of each heating bar 3 in each heating group on the heat dissipation surface of the heating core 1, so that the air outlet temperature of the air-heating PTC heater is more uniform, specifically as Figure 5 and Figure 6 shown:

[0039] The heating core 1 has 6 heating bars 3 and 7 heat dissipation bars 2, which are respectively represented by ①, ②, ③, ④, ⑤ and ⑥ Figure 6 for the 6 heating bars 3 arranged in sequence from left to right in , among which, ①, ③, ④ and ⑥ form a heating group, and ② and ⑤ form another heating group. When only the heating group composed of ② and ⑤ is enabled, it is in the low gear; when only the heating group composed of ①, ③, ④ and ⑥ is enabled, it is in the medium gear; when both heating groups are enabled, it is in the high gear. The positive electrode connection bar 15 located above all positive electrode terminals 12 is in an inverted mountain shape, that is, it has three downward protrusions and connection parts 16 respectively connected to the positive electrode terminals 12 of ①, ③, ④ and ⑥. The positive electrode connection bar 15 located below all positive electrode terminals 12 is in a concave shape, that is, it has two upward protrusions and connection parts 16 respectively connected to the positive electrode terminals 12 of ② and ⑤. The two positive electrode connection bars 15 are coupled to each other and maintain a certain distance to ensure insulation performance;

[0040] It can be seen that not only are all the heating bars 3 in each heating group symmetrically distributed about the center of the heating core 1 in the stacking direction, but also the positive extreme ends 12 in the two heating groups alternate at least three times in the stacking direction, thus eliminating the situation where all the heating bars 3 included in one heating group are concentrated in the middle of the heat dissipation surface of the heating core 1, and all the heating bars 3 included in the other heating group are distributed on both sides of the heat dissipation surface of the heating core 1. This ensures the degree of dispersion of each heating bar 3 on the heat dissipation surface of the heating core 1. Whether only the heating group composed of ①, ③, ④, and ⑥ or the heating group composed of ② and ⑤ is enabled, the air outlet temperature of the air-heating PTC heater is relatively uniform.

[0041] In addition, the design concept of the structure and arrangement form of the positive connection bar 15 itself in the present invention is not limited to the air-heating PTC heater with three power levels. Please refer to Figure 10 As shown, this embodiment also gives the structure and arrangement form of each positive connection bar 15 when the above design concept is applied to the air-heating PTC heater with four power levels.

[0042] Furthermore, please refer to Figure 5 and Figure 6 , an insulating fixing plate 17 is provided at one end of the heating core 1 where all the positive extreme ends 12 and negative extreme ends 13 are located. The insulating fixing plate 17 has two through accommodating grooves, and the two accommodating grooves respectively match the two positive connection bars 15. The two positive connection bars 15 are respectively fixed in the corresponding accommodating grooves; in this embodiment, the insulating fixing plate 17 is formed by injection molding and filling with melted nylon material between the two positive connection bars 15;

[0043] In this way, by setting the insulating fixing plate 17, not only can the positions of the two positive connection bars 15 be well restricted to avoid contact between the two connection bars due to the vibration during vehicle driving, but also by separating the two positive connection bars 15 through the insulating fixing plate 17, the insulation performance between the two positive connection bars 15 can be further improved, making the air-heating PTC heater have better reliability.

[0044] Furthermore, please refer to Figure 5 , there is a spacing between the positive connection bar 15 and the negative connection bar 14 in the length direction of the heating bar 3; in this way, the insulation between the positive connection bar 15 and the negative connection bar 14 can be further improved.

[0045] In addition, as Figure 5 and Figure 6As shown, the positive connection bar 15 located on the side of all positive terminals 12 close to all negative terminals 13 is correspondingly connected to the heating group composed of ①, ③, ④, and ⑥. Since the power of the heating group is higher and the working current is larger than that of the heating group composed of only ② and ⑤, the positive connection bar 15 located on the side of all positive terminals 12 close to all negative terminals 13 needs to have a higher current-carrying capacity.

[0046] For this, please refer to Figure 5 and Figure 6 In this embodiment, the length of the positive terminal 12 is greater than that of the negative terminal 13. The negative connection bar 14 is penetrated by each negative terminal 13 and connected to the position near the end of the negative terminal 13. The positive connection bar 15 is penetrated by the corresponding positive terminals 12 and connected to the position near the end of the positive terminal 12. Then, the negative connection bar 14 is located between the positive connection bar 15 and the heating core 1. In this way, on the plane where the positive connection bar 15 is located on the side of all positive terminals 12 close to all negative terminals 13, it can extend and widen towards the side where all negative terminals 13 are located without affecting the thickness of the heating core 1, thereby improving the current-carrying capacity of the positive connection bar 15 to ensure the stable operation of the heating group composed of ①, ③, ④, and ⑥.

[0047] Furthermore, please refer to Figure 5 In this embodiment, both ends of the negative connection bar 14 are bent and extend away from the heating core 1 and are fixedly connected to the insulating fixing plate 17. In this way, by fixing the positive connection bar 15 and the negative connection bar 14 with the insulating fixing plate 17, the insulating fixing plate 17, the positive connection bar 15, and the negative connection bar 14 can form a relatively stable overall structure, which can further avoid the occurrence of faults caused by the contact between the positive connection bar 15 and the negative connection bar 14 due to the vibration of the vehicle during operation.

[0048] In this embodiment, negative fixing plates 18 are embedded at positions corresponding to both ends of the negative connection bar 14 on the insulating fixing plate 17. The negative fixing plates 18 are made of conductive materials. Both ends of the negative connection bar 14 are bent and extend away from the heating core 1 and penetrate the corresponding negative fixing plates 18. Wires 23 are welded to any negative fixing plate 18 and two positive connection bars 15 for the installation and connection of the heating core 1.

[0049] In a warm air PTC heater, the heat generated by the PTC heating sheet 9 in the heating strip 3 needs to be transferred to the heat dissipation strip 2 through the electrode strip 8, the insulating paper 10, and the aluminum tube 7, and then transferred to the air through the aluminum frame 4 and the heat dissipation fins 5 of the heat dissipation strip 2. The entire heat transfer system will form a thermal resistance. The temperature of the heating core 1 under different working conditions and the temperature of the heated air form a temperature difference. The smaller the temperature difference, the better the heat transfer performance of the entire heat transfer system, the higher the heating efficiency, and the lower the working temperature of the PTC heating sheet 9. This not only improves the heating efficiency of the warm air PTC heater but also extends the service life of the PTC heating sheet 9 and reduces the occurrence of thermal attenuation or breakdown of the PTC heating sheet 9. Currently, to ensure the structural strength of the aluminum tube 7 of the heating strip 3, the wall thickness of the aluminum tube 7 is generally 0.8 - 1.0 mm, and the heat dissipation fins 5 are generally processed by the folding tooth method and adopt a heat dissipation rib structure. This results in a large thermal resistance between the aluminum tube 7 and the heat dissipation fins 5 and a low heat dissipation efficiency, thus affecting the heating efficiency of the warm air PTC heater and the service life of the PTC heating sheet 9.

[0050] In response, the present invention has improved the structures of the aluminum tube 7 and the heat dissipation fins 5 respectively, as follows:

[0051] Improvement for the aluminum tube 7: Please refer to Figure 3 and Figure 7 , both short sides of the cross-section of the aluminum tube 7 are in a V shape with the openings facing outside the aluminum tube 7. The short sides of the cross-section of the aluminum tube 7 are transitioned through an arc segment 19 that bends outward from the middle of the V shape towards the outside of the aluminum tube 7. The wall thickness of the aluminum tube 7 on the side wall where the long side is located in the cross-section is 0.6 - 0.8 mm. That is, as shown in Figure 7 , the side wall of the aluminum tube 7 where the short side is located in the cross-section is in a V shape, and a recessed groove is formed at R on the outer side of the side wall.

[0052] In this way, although the wall thickness of the side wall of the aluminum tube 7 where the long side is located in the cross-section is reduced from 0.8 - 1.0 mm to 0.6 - 0.8 mm, when the aluminum tube 7 rolls and compresses the distance between the two side walls where the long side is located in the cross-section, due to the existence of the groove, the side wall of the aluminum tube 7 where the short side is located in the cross-section is more likely to deform at the groove, which can prevent the two side walls where the long side is located in the cross-section of the aluminum tube 7 from deforming. It is beneficial to ensure the flatness of the two side walls and maintain the pressing force on the electrode strip 8 and the PTC heating sheet 9 inside the aluminum tube 7, making the PTC heating sheet 9, the electrode strip 8, and the aluminum tube 7 closely fit in sequence. Furthermore, it reduces the contact resistance between the PTC heating sheet 9 and the electrode strip 8 and the thermal resistance among the electrode strip 8, the PTC heating sheet 9, and the aluminum tube 7, improving the heat transfer efficiency of the heating core 1. Additionally, through CFD design and verification, when the wall thickness of the side wall of the aluminum tube 7 where the long side is located in the cross-section is 0.6 - 0.8 mm, the heat transfer efficiency of the heating core 1 is the highest.

[0053] Improvements to the heat dissipation fins 5: Please refer to Figure 2 , Figure 8 and Figure 9 . The heat dissipation strip 2 includes a rectangular aluminum frame 4 formed by aluminum plates. In the aluminum frame 4, there are heat dissipation fins 5 extending in a zigzag manner along the length direction of the aluminum frame 4. A plurality of curved surfaces 6 formed due to the zigzag extension on the heat dissipation fins 5 are in contact with the side walls in the width direction of the aluminum frame 4. On a plurality of inclined surfaces 20 formed due to the zigzag extension on the heat dissipation fins 5 and spaced along the length direction of the aluminum frame 4, there are multiple window structures. The window structure includes a square hole 21 penetrating through the inclined surface 20. Inside the square hole 21, there are multiple long strip-shaped blades 22 arranged in parallel at intervals. The blades 22 are arranged along the extension direction of the heat dissipation fins 5, and the blades 22 form an angle with the inclined surface 20 where they are located. Both ends of the blades 22 are fixedly connected to the inner wall of the square hole 21. During implementation, the heat dissipation fins 5 are formed by rolling aluminum foil on a gear. The gear is formed by stacking multiple cutting tools. When the aluminum foil is rolled by the gear to form the heat dissipation fins 5 extending in a zigzag manner, the window structure is simultaneously formed on the inclined surface 20. In this embodiment, there are 3 long strip-shaped blades 22 arranged in parallel at intervals inside the square hole 21. Each inclined surface 20 has 2 such window structures and is spaced along the thickness direction of the aluminum frame 4. The angle between the blade 22 and the inclined surface 20 where it is located is 25 - 35°. Through fluid analysis and CFD analysis of the heat dissipation fins 5, compared with the ordinary heat dissipation fins 5 using rib stamping structures, the heat dissipation efficiency is increased by at least 5%.

[0054] In summary, through structural design, the present invention improves the heat dissipation performance of the heat dissipation fins 5, reduces the wall thickness of the side wall where the long side is located on the cross-section of the aluminum tube 7, and further reduces the contact resistance between the PTC heating sheet 9 and the electrode strip 8 and the thermal resistance among the electrode strip 8, the PTC heating sheet 9, and the aluminum tube 7. Compared with the original structure, the heating efficiency of the air-heating PTC heater is increased by 6.3%, the electro-thermal conversion efficiency is increased by 1.5%, the service life of the heating core 1 is also improved to a certain extent, and the material cost is reduced by 2%.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and do not limit the technical solutions. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the present technical solution should be covered within the scope of the claims of the present invention.

Claims

1. A grouped air-heating PTC heater, comprising a heating core body. The heating core body includes a plurality of heat dissipation strips and heating strips that are alternately stacked along its width direction. The positive and negative end heads of all the heating strips are located at the same end of the heating core body. All the positive end heads and all the negative end heads are respectively located on both sides in the thickness direction of the heating core body. A negative connection strip and a positive connection strip are provided at the end of the heating core body where the positive and negative end heads are located. Both the negative connection strip and the positive connection strip extend along the width direction of the heating core body. The negative connection strip is connected to all the negative end heads, and all the heating strips are divided into two heating groups with unequal numbers of heating strips; it is characterized in that: All heating bars in each heating group are symmetrically distributed around the center in the width direction of the heating core. There are two positive connection bars. The two positive connection bars correspond to the two heating groups one by one. Multiple connection parts are formed by protrusions on the positive connection bars, and the connection parts face the multiple positive terminals in the corresponding heating group respectively, and the connection parts are connected to the positive terminals one by one. The positive terminals in the two heating groups alternate at least three times in the width direction of the heating core. The two positive connection bars are located in the same plane in the length direction of the heating core. The two positive connection bars are respectively located on both sides of all positive terminals in the thickness direction of the heating core. An insulating fixing plate is provided at one end of the heating core where the positive terminals and negative terminals are located. The insulating fixing plate has two through accommodating grooves, and the two accommodating grooves respectively match the two positive connection bars, and the two positive connection bars are respectively fixed in the corresponding accommodating grooves.

2. The grouped air-heating PTC heater according to claim 1, wherein: There is a spacing between the positive connection bar and the negative connection bar in the length direction of the heating core.

3. The grouped air-heating PTC heater according to claim 2, wherein: The distance between the heating core and the positive connection bar is greater than the distance between the heating core and the negative connection bar. Both ends of the negative connection bar are bent and extend away from the heating core and are fixedly connected to the insulating fixing plate.

4. The grouped air-heating PTC heater according to claim 1, wherein: Wires are welded to both the negative connection bar and the two positive connection bars.

5. The grouped air-heating PTC heater according to claim 1, characterized in that: The heating bar includes an aluminum tube with a rectangular cross-section. Two electrode bars are arranged in the aluminum tube in parallel and facing each other and extending along the length direction of the aluminum tube. The electrode bars are parallel to the side wall where the long side is located in the cross-section of the aluminum tube. The same ends of the two electrode bars have extension parts extending out of the aluminum tube along the length direction of the aluminum tube to form the positive terminal and the negative terminal. Both short sides in the cross-section of the aluminum tube are in a V shape with the opening facing outside the aluminum tube, and the short sides in the cross-section of the aluminum tube are transitioned through an inward concave arc section in the middle of the V shape.

6. The grouped air-heating PTC heater according to claim 5, wherein: The wall thickness of the side wall where the long side is located in the cross-section of the aluminum tube is 0.6 - 0.8 mm.

7. The grouped air-heating PTC heater according to claim 1, wherein: The heat dissipation bar includes a rectangular aluminum frame surrounded by an aluminum plate. Heat dissipation fins are arranged in the aluminum frame in a zigzag extension along the length direction of the aluminum frame. A number of curved surfaces formed by the zigzag extension of the heat dissipation fins are in contact with the side walls in the width direction of the aluminum frame. A number of inclined surfaces formed by the zigzag extension and spaced along the length direction of the aluminum frame each have a plurality of window structures. The window structure includes a square hole penetratingly opened on the inclined surface. A plurality of long strip-shaped blades are arranged in parallel and spaced in the square hole. The blades are arranged along the extension direction of the heat dissipation fins. The blades have an angle with the inclined surface where they are located, and both ends of the blades are fixedly connected to the inner wall of the square hole.

8. The grouped air heating PTC heater according to claim 7, wherein: Three long strip-shaped blades are arranged in parallel and spaced in the square hole. The plurality of window structures on each inclined surface are spaced along the thickness direction of the aluminum frame. The angle between the blade and the inclined surface where it is located is 25 - 35°.

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