High-power-density PTC (Positive Temperature Coefficient) water heater

Abstract

The invention discloses a high-power-density PTC water heater, and relates to the field of heaters, the high-power-density PTC water heater comprises a PTC heating body, a shell and a wire harness, the PTC heating body comprises a PTC heating core and an aluminum casting, the PTC heating core comprises a PTC sheet, an electrode sheet and an insulation protection frame, and the upper and lower parts of the PTC sheet are connected with the electrode sheet through heat-conducting glue; the aluminum casting comprises a PTC heating core mounting seat, an upper cover and a flange I, a mounting cavity matched with the PTC heating core is formed in the middle of the PTC heating core mounting seat, and flow guide ribs are arranged on the bottom surface of the PTC heating core mounting seat and the upper surface of the upper cover; the shell comprises a cavity for containing the PTC heating body, a water inlet, a water outlet and a flange II, and a liquid flowing channel is formed between the flow guide ribs and the cavity. Through innovative design of the structure, insulation, heat dissipation and liquid flow channels of the heater, the whole structure is simple, the size is small, the maximum power density of 58W / cm or above can be achieved, and the size, weight and cost of the heater are effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of heaters, and in particular to a high power density PTC water heater. Background Art

[0002] At present, PTC water heaters are widely used in various electrical and new energy vehicles with high safety requirements due to their advantages of no open flame, resistance to dry burning, and low dry burning temperature. The air conditioning system of traditional fuel vehicles uses the waste heat of the engine for heating. Since pure electric vehicles do not have engines, they are mainly heated by PTC water heaters. Existing PTC water heaters all include PTC heating bodies, shells and wiring harnesses. The PTC heating body includes a PTC sheet in the middle and electrode sheets on both sides, and is wrapped with 2 to 4 circles of PI insulating film on the outside, which plays the main role of insulation. However, the thermal conductivity of the PI insulating film itself is relatively poor. After wrapping several circles, the PTC transmission and heat dissipation are poor, the conversion rate between the temperature of the PTC and the outside temperature is poor, and the PI insulating film is easily punctured. Its shell is a U-shaped piece, and the PTC heating body is placed in the shell together with a wedge block. Because these three parts are separated and assembled together, there will be gaps, and the tight fit effect cannot be achieved after assembly. In other words, it is made by the "tightening" process (if you plug it in, you can pull it out), which is not an ideal fit, resulting in a decrease in the power stability of the product, thereby affecting the performance of the PTC power. In addition, the existing PTC water heaters are heavy in weight. Due to their low heating temperature, their power density is low, and the maximum can only reach about 35W / cm² (PTC thermistor area). When high power is required, it is often necessary to increase the size of the heater, or design a complex heat dissipation structure, which has high processing costs. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a high power density PTC water heater. Through the innovative design of the heater structure, insulation, heat dissipation and liquid flow channel, the overall structure is simple and the volume is small. The maximum power density of 58W / cm² (PTC thermistor area) can be achieved, effectively reducing the volume, weight and cost of the heater.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a high power density PTC water heater, comprising a PTC heating body, a shell and a wiring harness, the PTC heating body comprising a PTC heating core and a cast aluminum part, the PTC heating core comprising a PTC sheet, an electrode sheet and an insulating protection frame, the PTC sheet is bonded to the electrode sheet above and below by thermally conductive adhesive, the PTC sheet and the electrode sheet after bonding are surrounded by an insulating protection frame, and the end of the electrode sheet is provided with a pin; the cast aluminum part comprises a PTC heating core mounting seat, an upper cover and a flange I, the middle of the PTC heating core mounting seat is provided with an installation cavity for matching the PTC heating core, and the bottom surface of the PTC heating core mounting seat and the upper surface of the upper cover are both provided with guide ribs; the shell comprises a cavity for accommodating the PTC heating body, a water inlet and outlet and a flange II, and a liquid flow channel is formed between the guide rib and the cavity.

[0005] As a further improvement, an alumina ceramic sheet is provided between the PTC heating core, the PTC heating core mounting base and the upper cover.

[0006] As a further improvement, a sealing ring I is provided between the PTC heating core mounting base and the upper cover, and they are fixedly connected by screws.

[0007] As a further improvement, a temperature sensing probe is provided on one side of the shell.

[0008] As a further improvement, a protection box is provided on the outer side of the flange I, and a temperature controller and a temperature fuse are provided inside the protection box.

[0009] As a further improvement, a sealing ring II is provided between the flange I and the flange II.

[0010] As a further improvement, the housing is further provided with mounting ears.

[0011] The PTC sheet of the present invention is formed by arranging one or more PTC sheets in parallel. The multiple PTC sheets are connected in parallel. The PTC sheet and the electrode sheet can be bonded by silica gel or other high temperature resistant adhesives, or can be directly clamped.

[0012] Beneficial effects of the present invention: Through the innovative design of the heater structure, insulation, heat dissipation, and liquid flow channel, a modular structure is made, which is tightly connected to each other. Since the heated liquid completely wraps the PTC heating element, the shell temperature is relatively low (will not exceed the heated liquid), which has little impact on the surrounding components, and there is no need to design an additional thermal insulation protection structure, which greatly reduces the cost while reducing the volume. The overall structure is simple and the volume is small. The maximum power density of 58W / cm² (PTC thermistor area) can be achieved, effectively reducing the volume, weight and cost of the heater. The alumina ceramic sheet in this heater is a good carrier for insulation and thermal conductivity, and has a better effect than the PI insulating film, achieving both insulation and good thermal conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of a PTC heating core according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation of a PTC heating core according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a PTC heating body according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the installation of a PTC heater according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a housing according to an embodiment of the present invention; In the figure: 1. PTC sheet; 2. Electrode sheet; 3. Insulation protection frame; 4. PTC heating core; 5. Pin; 6. PTC heating core mounting base; 7. Upper cover; 8. Flange I; 9. Guide rib; 10. Sealing ring I; 11. Screw; 12. Cavity; 13. Water inlet and outlet; 14. Flange II; 15. Alumina ceramic sheet; 16. Temperature sensor; 17. Protection box; 18. Sealing ring II; 19. Mounting ear; 20. Sleeve. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] As shown in the accompanying drawings, a high power density PTC water heater includes a PTC heating body, a housing and a wiring harness. The PTC heating body includes a PTC heating core 4 and an aluminum casting. The PTC heating core 4 includes a PTC sheet 1, an electrode sheet 2 and an insulating protection frame 3. The entire PTC sheet 1 is composed of 8 PTC sheets arranged in parallel, and each PTC sheet is connected in parallel. The electrode sheet 2 is made of aluminum, copper or other conductive metal materials, and the thickness is set according to the working current. The electrode sheet 2 is made of a pin 5 or a pin-type structure, which is convenient for connection with a wire, welding, etc., and an insulating high-temperature resistant sleeve 20 is sleeved outside the pin 5. The PTC sheet is bonded to the electrode sheet 2 by thermal conductive glue at the top and bottom. The PTC sheet 1 and the electrode sheet 2 after bonding are surrounded by an insulating protection frame 3. The insulating protection frame 3 is made of high-temperature resistant plastic or other insulating and high-temperature resistant materials, which is used for positioning when installed in the aluminum casting and is insulated on all sides.

[0016] The cast aluminum part includes a PTC heating core mounting seat 6, an upper cover 7 and a flange Ⅰ8. The PTC heating core mounting seat 6 is provided with a mounting cavity in the middle thereof for matching with the PTC heating core 4. Alumina ceramic sheets 15 are provided between the PTC heating core 4, the PTC heating core mounting seat 6 and the upper cover 7 to achieve insulation and good heat conduction. Three guide ribs 9 are provided on the bottom surface of the PTC heating core mounting seat 6 and the upper surface of the upper cover 7; a wire lead-out hole is provided on the PTC heating core mounting seat 6 to lead the wires or pins on the electrode sheet 2 to the outside.

[0017] like Figure 6 As shown, the housing includes a cavity 12 for accommodating the PTC heating body, a water inlet and outlet 13 and a flange II 14. A liquid flow channel is formed between the guide rib 9 on the cast aluminum part and the cavity 12. The guide rib 9 can also increase the heat dissipation area. A sealing ring I 10 is provided between the PTC heating core mounting seat 6 and the upper cover 7, and the connection is fixed by screws 11 to prevent water leakage. The PTC heating core mounting seat 6 and the upper cover 7 can also be fixed by snaps. A temperature sensor 16 is provided on one side of the housing, and a protection box 17 is provided on the outside of the flange I 8. A thermostat and a temperature fuse are provided in the protection box 17. A pair of mounting ears 19 are also provided on the housing to match the terminal. A sealing ring II 18 is provided between the flange I 8 and the flange II 14 to prevent liquid leakage inside the cavity 12.

[0018] The parameters of existing conventional PTC water heaters are as follows: Rated voltage (platform) PTC Curie Temperature PTC Specifications W / piece Maximum power density Implementing functions 48V 245℃±10℃ 24*15 120W~130W 35W / cm² 8 chips with power up to 960~1040W 350V 220℃±7 24*15 100~115W 28W / cm² 8 chips with power of 800~920W 600V 210~220℃ 24*15 90~100W 27W / cm² 8 chips with power of 720~800W The parameters of the present invention are as follows: Rated voltage (platform) PTC Curie Temperature PTC Specifications W / piece Maximum power density Implementing functions 48V 245℃±10℃ 24*15 200~210W 58W / cm² 8 chips with power up to 1600~1680W 350V 220℃±7℃ 24*15 165~185W 51W / cm² 8 chips with power up to 1320~1480W 600V 210~220℃ 24*15 150~170W 47W / cm² 8 chips with power up to 1200~1360W

Claims

1. A high power density PTC water heater, comprising a PTC heating element, a housing and a wiring harness, characterized in that: The PTC heating body comprises a PTC heating core (4) and a cast aluminum part. The PTC heating core (4) comprises a PTC sheet (1), an electrode sheet (2) and an insulating protection frame (3). The upper and lower parts of the PTC sheet (1) are bonded to the electrode sheet (2) by heat-conducting adhesive. After bonding, the PTC sheet (1) and the electrode sheet (2) are surrounded by an insulating protection frame (3). The end of the electrode sheet (2) is provided with a pin (5). The cast aluminum part comprises a PTC heating core mounting seat (6), an upper cover (7) and a flange I (8). The middle of the PTC heating core mounting seat (6) is provided with a mounting cavity for matching the PTC heating core (4). The bottom surface of the PTC heating core mounting seat (6) and the upper surface of the upper cover (7) are both provided with guide ribs (9). The outer shell comprises a cavity (12) for accommodating the PTC heating body, a water inlet and outlet (13) and a flange II (14). A liquid flow channel is formed between the guide rib (9) and the cavity (12).

2. A high power density PTC water heater as claimed in claim 1, characterized in that: An alumina ceramic sheet (15) is provided between the PTC heating core (4), the PTC heating core mounting seat (6) and the upper cover (7).

3. A high power density PTC water heater as claimed in claim 1, characterized in that: A sealing ring I (10) is provided between the PTC heating core mounting seat (6) and the upper cover (7), and they are fixedly connected by screws (11).

4. A high power density PTC water heater as claimed in claim 1, characterized in that: A temperature sensing probe (16) is provided on one side of the housing.

5. A high power density PTC water heater as claimed in claim 1, characterized in that: A protection box (17) is provided on the outside of the flange I (8), and a temperature controller and a temperature fuse are provided inside the protection box (17).

6. A high power density PTC water heater as claimed in claim 1, characterized in that: A sealing ring II (18) is provided between the flange I (8) and the flange II (14).

7. A high power density PTC water heater as claimed in claim 1, characterized in that: The housing is also provided with a mounting ear (19).

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