Patent Description:
Air-conditioning and heating system of a conventional fuel vehicle generally use the waste heat of flue gas or circulating cooling water of the engine as a heating source. However, for a hybrid electric vehicle or a pure electric vehicle, there is no sufficient waste heat for heating of the interior the vehicle. Furthermore, under a condition of extremely low temperature, the heat source is also used to defrost and defog. Thus, an auxiliary electric heating device is needed.

Therefore, an electric heating device using a PTC (Positive Temperature Coefficient ) heating assembly is proposed. The electric heating device has a casing and at least one PTC heating assembly disposed inside the casing. The conventional PCT heating assembly includes two electrical insulation plates, a PTC heating element arranged between the two electrical insulation plates and two contact plates (electrode plates). The PCT heater is fixedly clamped by the two contact plates. As the PTC heating assembly includes a plurality of the PTC heating elements, the plurality of the PTC heating elements are difficultly fixed due to different thicknesses or improper arranging positions of the PTC heating elements. Furthermore, because the PTC heating element is very sensitive to the temperature and the heating effects of the plurality of the PTC heating elements are not identical, the plurality of the PTC heating elements may contact each other during heating, thus causing that the plurality of the PTC heating elements can not give full play to their heating performance. In addition, when used in the electric vehicle, the PTC heating element subjects to a high voltage, so that a distance between the two electrode plates is increased in order to avoid arc discharge occurred between the two electrode plates, thus causing the volume and the occupied space of the PTC heating element large.

Conventional PTC electric heating assembly are disclosed in <CIT> and <CIT>.

Embodiments of the present invention seek to solve at least one of the problems existing in the prior art to at least some extent.

According to embodiments of a first broad aspect of the present invention there is provided a PTC electric heating assembly as defined in claim <NUM>.

According to embodiments of a second broad aspect of the present invention, there is provided an electric heating device as defined in claim <NUM>.

According to embodiments of a third broad aspect of the present invention, there is provided an electric vehicle, employing an air conditioning system, the air conditioning system includes the electric heating device according to the second aspect of the present invention.

With the PTC electric heating assembly and the electric heating device according to embodiments of the present invention, the PTC heating elements are fixed within the fixing unit of the insulation fixing frame respectively, so that the PTC heating elements are stably positioned and isolated from each other by the insulation fixing frame, thus avoiding contacting of the PTC heating elements, reducing the interference among the PTC heating elements during the operation, giving full play to the heating performance thereof, improving the heating power thereof and increasing the heating effect of the electric heating device.

The embodiments described herein with reference to drawings are explanatory, illustrative, and used to generally understand the present invention.

In the specification, Unless specified or limited otherwise, relative terms such as "central", "longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "upper", "horizontal", "vertical", "above", "below", "up", "top", "bottom" as well as derivative thereof (e.g., "horizontally", "downwardly", "upwardly", etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the present invention be constructed or operated in a particular orientation.

In addition, terms such as "first" and "second" are used herein for purposes of description and are not intended to indicate or imply relative importance or significance. Thus, characteristics defined by the terms "first" and "second" may indicatively or impliedly comprise one or plurality of the characteristics. In the description of the present invention, term "plurality of" means two or more than two, unless there is another certain definition.

A PTC electric heating assembly <NUM> according to an embodiment of the present invention will be described below with reference to the drawings. For example, an electric heating device having the PTC electric heating assembly <NUM> may be used in an electric vehicle, however, the present invention is not limited thereto.

As shown in <FIG>, the PTC electric heating assembly <NUM> according to embodiments of the present invention comprises a PTC heating module <NUM> and two electrode plates <NUM> disposed at two sides (left and right sides in <FIG>) of the PTC heating module. In other words, each electrode plate <NUM> has two side surfaces opposite to each other (left side surface and right surface in <FIG>). The two electrode plates <NUM> are spaced apart from each other and the left side surface of one electrode plate <NUM> is opposite to the right side surface of the other electrode plate <NUM>. The PTC heating module <NUM> is disposed between the side surfaces opposite to each other of the two electrode plates <NUM>.

As shown in <FIG>, the PTC heating module <NUM> comprises an insulation fixing frame <NUM> and a plurality of PTC heating elements <NUM>. The insulation fixing frame <NUM> has a plurality of fixing units <NUM> such as fixing grooves or fixing space, and the plurality of fixing units <NUM> are spaced apart from one another. The PTC heating elements <NUM> are disposed in the fixing units <NUM> in a one-to-one correspondence relationship, so that the PTC heating elements <NUM> are isolated from each other. In other words, the insulation fixing frame <NUM> is used to fix the plurality of the PTC heating elements <NUM> therein and isolate the adjacent PTC heating elements <NUM> from each other. Thus, the PTC heating elements <NUM> can be fixed stably, the interference with each other during operation can be reduced, and the PTC heating elements 21can give full play to the heating performance thereof.

As shown in <FIG>, the PTC heating element <NUM> of the PTC heating module <NUM> is the heating element of the PTC electric heating assembly <NUM>. The PTC heating module <NUM> includes at least two PTC heating elements <NUM>. In some embodiments, as shown in <FIG>, the PTC heating module <NUM> includes nine PTC heating elements <NUM>. However, the number of the PTC heating elements <NUM> is not limited and adjustable according to the heating requirements.

In some embodiments, the PTC heating elements <NUM> may be ceramic PTC heating pieces, and conductive electrodes (not shown) are disposed on opposite side surfaces of the ceramic PTC heating pieces by spraying or printing, and the conductive electrodes may be silver electrodes.

As shown in <FIG>, the heating module <NUM> comprises the insulation fixing frame <NUM> and the PTC heating elements <NUM> disposed in the insulation fixing frame <NUM>. As shown in <FIG>, in some embodiments, the insulating fixing frame <NUM> comprises a plurality of first isolating bars <NUM> and a plurality of second isolating bars <NUM>. The first isolating bars <NUM> are parallel to and spaced apart from one another, and the second isolating bars <NUM> are parallel to and spaced apart from one another. Each of the second isolating bars is perpendicular to and intersected with the plurality of the first isolating bars <NUM> so as to form a plurality of fixing units <NUM>.

As shown in <FIG>, in this embodiment, the insulation fixing frame <NUM> comprises two first isolating bars <NUM> and two second isolating bars <NUM>. The two first isolating bars <NUM> are parallel to and spaced from each other by a first predetermined interval, and the two second isolating bars <NUM> are parallel to and spaced from each other by a second predetermined interval. Each of the first isolating bars <NUM> is perpendicular to and intersected with the two second isolating bars <NUM> so as to form nine fixing units <NUM> such as fixing grooves or fixing spaces, thus providing nine mounting positions for nine PTC heating elements <NUM>. A person skilled in the art will appreciate that the number of the fixing units <NUM> can be determined by the number of the PTC heating elements <NUM>, then the number of the first isolating bars <NUM> and the second isolating bars <NUM> are further determined. A person skilled in the art will appreciate that the insulation fixing frame <NUM> is not limited to the structure and configuration shown in <FIG>.

As shown in <FIG>, the two first isolating bars <NUM> are disposed along a width direction K of the PTC heating elements <NUM>, and a distance between the two first isolating bars <NUM> is equal to a length of the PTC heating elements <NUM> (a size of the PTC heating element <NUM> in a length direction C thereof), so that the PTC heating element <NUM> is positioned in the length direction C efficiently.

The two second isolating bars <NUM> are disposed along the length direction C of the PTC heating elements <NUM>, and a distance between the two second isolating bars <NUM> is equal to a width of the PTC heating elements <NUM> (a size of the PTC heating element <NUM> in the width direction K thereof), so that the PTC heating element <NUM> is positioned in the width direction K efficiently.

Furthermore, as shown in <FIG>, in the length direction C, the adjacent PTC heating elements <NUM> are spaced apart from each other by the first isolating bars <NUM>, and in the width direction K, the adjacent PTC heating elements <NUM> are spaced apart from each other by the second isolating bars <NUM>. The adjacent PTC heating elements <NUM> are spaced apart from each other by the first isolating bars <NUM> and/or the second isolating bars <NUM>, thus reducing the mutual influence of the PTC heating elements <NUM> during the operation, so that the PTC heating elements <NUM> can be improved in heating power thereof and give full play to the heating performance thereof.

As shown in <FIG> and <FIG>, the insulation fixing frame <NUM> is disposed between the two electrode plates <NUM> and may be adhered to the two electrode plates <NUM> by an adhesive, so that a thickness of the insulation fixing frame <NUM> is substantially equal to that of the PTC heating elements <NUM>, and a tolerance of -<NUM>% to <NUM>% may be allowed.

In some embodiments, the thickness of the insulation fixing frame <NUM> is equal to that of the PTC heating elements <NUM>, in other words, thicknesses of the first isolating bar <NUM> and/or the second isolating bar <NUM> are equal to that of the PTC heating elements <NUM>, so that the insulation fixing frame <NUM> is fixed between the electrode plates <NUM> reliably, thus fixing the PTC heating elements <NUM> therein reliably, without affecting proper contacts between the PCT heating elements <NUM> and the electrode plates <NUM>.

Thus, the PTC heating elements <NUM> are isolated and positioned in the length direction C and the width direction K by the insulation fixing frame <NUM>, and are clamped and held between the two electrode plates <NUM> in the thickness direction (the up and down direction in <FIG> or the right and left direction in <FIG>), so that the PTC heating elements <NUM> can be efficiently positioned.

Conventionally, a person skilled in the art will appreciate that, when the PTC electric heating assembly <NUM> is used under a high voltage condition, in order to avoid the arc discharge occurred between the two electrode plates <NUM> and meet the safe standard, the requirements for the distance between the two electrode plates <NUM> are strict. Consequently, the volume of the PTC electric heating assembly <NUM> is increased.

However, in some embodiments of the present invention, the insulation fixing frame <NUM> is made of a material having a high temperature resistance and a high voltage resistance, so that a high voltage resistance between the two electrode plates <NUM> is improved, a possibility of the arc discharge occurred between the two electrode plates <NUM> is reduced and the PTC heating elements <NUM> are prevented from being broken down.

In some examples, advantageously, the insulation fixing frame <NUM> having the high voltage resistance and high temperature resistance is made of an organic polymer, such as organic silicon or polyimide, with a thermal conductivity between <NUM>. 02W/(m•K) and <NUM>. The insulation fixing frame <NUM> may be manufactured by a process of injection molding. With the insulation fixing frame <NUM>, an insulating performance between the two electrode plates <NUM> is efficiently increased, so that the PTC electric heating assembly <NUM> can be adapted to a high voltage condition, and the safety and adaptability thereof are improved.

As shown in <FIG> and <FIG>, the electrode plates is made of a conductive material, such as aluminum, copper, stainless steel, aluminum alloy, copper alloy and nickel base alloy. A leading out terminal <NUM> for coupling to a power supply is fixed on an upper end of the insulation fixing frame <NUM> by a welding or riveting. In order to ensure the proper contact between the PTC heating module <NUM> and the electrode plate <NUM>, the area of the side surface of the electrode plates <NUM> is larger than or equal to that of the PTC heating module <NUM>. More advantageously, the area of the side surface of the electrode plate <NUM> is larger than that of the PTC heating module <NUM>, so that the electrode plates <NUM> extend upwardly and/or downwardly beyond the PTC heating module <NUM> so as to form extending portions <NUM>.

As shown in <FIG>, the electrode plates <NUM> extend downwardly beyond the low edges of the PTC heating module <NUM> so as to form the extending portions <NUM> at the bottom ends of the electrode plates <NUM>. A heat conducting sealing glue (not shown) such as polyimide may be filled between the extending portions <NUM> of the two electrode plates <NUM>, so as to insulate the two electrode plates <NUM> and avoid a short circuit therebetween.

As shown in <FIG>, in some embodiments, the thicknesses of the two electrode plates <NUM> are decreased gradually along the up and down direction, in other words, both of the front surface (left surface in <FIG>) and the rear surface (right surface) of each of the two electrode plates <NUM> are trapezia. The inner surface of each of the two electrode plates <NUM> facing to the insulation fixing frame <NUM> is a vertical surface, and the outer surface of each of the two electrode plates <NUM> away from the insulation fixing frame <NUM> is an inclined surface, in other words, the outer surface are inclined inwardly in the up and down direction.

A person skilled in the art will appreciate that the thickness of one electrode plate <NUM> may be decreased gradually along the up and down direction, and the thickness of the other electrode plate <NUM> may not be changed. The PTC electric heating assembly <NUM> can be easily mounted, positioned and disassembled, because the thickness of at least one electrode plate <NUM> is decreased gradually along the up and down direction, which will be described below.

As shown in <FIG>, it is known that an electric conductivity between the PTC heating elements <NUM> and the electrode plates <NUM> as well as the value of the contact resistance has a great influence on the voltage resistance performance of the PTC heating module <NUM>, especially on the safety and the reliability of the PTC heating module <NUM> under a long time and a high voltage operation condition. In the related art, the PTC heating elements and the electrode plates of the conventional electric heating assembly are contacted directly and rigidly, so that an interfacial gap is formed therebetween. Under the high voltage condition, this contacting manner can easily cause the PTC heating elements <NUM> broken down due to the arc discharge, thus resulting in the short circuit.

According to the present invention, a contact electrode <NUM> is disposed between the PTC heating module <NUM> and each of the electrode plates <NUM>, and adhered to the insulation fixing frame <NUM> by an adhesive. More specifically, the contact electrode <NUM> is configured as a compressible conducting layer or an elastic sheet. The compressible conducting layer comprises polymer and a conducting material compounded with the polymer. The polymer in the compressible conducting layer comprises one or more selected from polyimide, PTFE, organic silicon resin and ethoxyline resin. The conducting material comprises one or more selected from metal fiber, metal particles, metal mesh, carbon and graphite.

A plurality of contact points (not shown) may be formed on two side surfaces of the elastic sheet, the contact point on one side surface of the elastic sheet is contacted with the PTC heating elements <NUM>, and the contact point on the other side surface of the elastic sheet is contacted with the electrode plate <NUM>. Both the compressible conducting layer and the elastic sheet have elasticity so as to reduce the contact resistance and not affect the heat conduction at the interface, comparing with the conventional direct contact between the rigid PTC heating elements <NUM> and the electrode plates <NUM>. Thus, the heat generated by the PTC heating elements <NUM> can be conducted to the electrode plates <NUM> fully, and the PTC heating elements <NUM> can be used safely for a long time under the high voltage condition.

As shown in <FIG> and <FIG>, the PTC electric heating assembly <NUM> further comprises an insulating layer <NUM> disposed on the outer surface of each of the electrode plates <NUM>, and the insulating layer <NUM> has a U-shape section so as to cover the outer surface and the bottom surface of the electrode plate <NUM>, thus the electrode plates <NUM> are insulated from the thermal conducting grooves <NUM>. The insulating layer <NUM> is an electrical-insulation and thermal conducting film and made of a material with an electrical insulatibity and a high thermal conductivity, so as to reduce the heat loss. For example, the insulating layer <NUM> may be made of a thermal conductive shim or a ceramic insulating material.

An electric heating device according to embodiments of the present invention will be described below with reference to the drawings.

As shown in <FIG>, the electric heating device comprises a casing <NUM> and a plurality of PTC electric heating assemblies <NUM> mounted in the casing <NUM>. The PTC electric heating assemblies <NUM> may be the PTC electric heating assemblies described with reference to the above embodiments, so that detailed description thereof are omitted here.

More specifically, the casing <NUM> has a heating chamber <NUM> and a medium circulating cavity <NUM> therein. The heating chamber <NUM> has a plurality of thermal conducting grooves <NUM>, in other words, the heating chamber <NUM> for heating the medium is formed by the thermal conducting grooves <NUM>. The medium circulating cavity <NUM>, for containing the medium and allowing the medium circulating therein, has a medium inlet <NUM> for feeding the medium into the medium circulating cavity <NUM> and a medium outlet <NUM> for discharging the medium out of the medium circulating cavity <NUM>. The medium circulating cavity <NUM> and the heating chamber <NUM> (the thermal conducting grooves <NUM>) are hermetically isolated. The PTC electric heating assemblies <NUM> are mounted into the thermal conducting grooves <NUM> in one to one correspondence relationship.

In order to facilitating manufacturing, mounting, positioning and disassembling of the PTC electric heating assemblies <NUM>, and to improve the contact between the PTC electric heating assembly <NUM> and side surfaces of the thermal conducting grooves <NUM>, as described above, the thicknesses of the electrode plates <NUM> is decreased gradually along the up and down direction, in other words, at least one side surface of the electrode plates <NUM> is inclined inwardly in the up and down direction.

Correspondingly, at least one side surface of the thermal conducting grooves <NUM> is inclined inwardly in the up and down direction so as to adapt to the inclined side surface of the electrode plate <NUM>, in other words, the vertical section of the thermal conducting groove <NUM> is a trapezia. Thus, the PTC electric heating assemblies <NUM> may be embedded in the thermal conducting grooves <NUM> conveniently, and a desire contact between the PTC electric heating assemblies <NUM> and the thermal conducting grooves <NUM> may be formed by a press force applied to the PTC electric heating assemblies <NUM> by the side surface of the thermal conducting grooves <NUM> during mounting of the PTC electric heating assemblies <NUM>. A person skilled in the art will appreciate that one side surface of each of the thermal conducting grooves <NUM> may be a vertical surface, and the other side surface thereof may be an inclined surface. Alternatively, both side surfaces of each of the thermal conducting grooves <NUM> may be the inclined surface.

As described above, the PTC electric heating assemblies <NUM> are embedded in the thermal conducting grooves <NUM> respectively, so that the heat generated by the PTC electric heating assemblies <NUM> may be conducted to the walls of thermal conducting grooves <NUM>. In this case, the walls of thermal conducting grooves <NUM> not only isolate the medium from the PTC electric heating assemblies <NUM>, but also conduct the heat. The walls of thermal conducting grooves <NUM> may be made of a metal having a good conducting performance, such as aluminum or aluminum alloy.

During manufacturing and assembling the PTC electric heating assemblies <NUM>, firstly the insulation fixing frame <NUM> is disposed onto one electrode plate <NUM> (or the contact electrode <NUM>), then the PCT heating elements <NUM> are disposed into the fixing units <NUM> of the insulation fixing frame <NUM> respectively. Next, the other electrode plate <NUM> (or the other contact electrode <NUM>) is disposed on the side of the insulation fixing frame <NUM> away from the one electrode plate <NUM>. The thermally conductive sealing glue is filled between edges the two electrode plates <NUM>. Finally the insulating layer <NUM> is coated on the outer surfaces and the bottom surfaces of the two electrode plates <NUM> so as to form the PTC electric heating assemblies <NUM>.

The assembled PTC electric heating assemblies <NUM> are embedded into the thermal conducting grooves <NUM> respectively. In use, the medium is fed into the medium circulating cavity <NUM> through the medium inlet <NUM> of the casing <NUM>, then the PTC electric heating assemblies <NUM> are energized, the PTC heating elements <NUM> start heating. The heat is conducted to the medium via the electrode plates <NUM>, insulating layer <NUM> and the walls of the thermal conducting grooves <NUM>. The medium flows out of the medium circulating cavity <NUM> through the medium outlet <NUM> of the casing <NUM> for heating, defrosting and defogging the interior of a vehicle.

With the PTC electric heating assemblies <NUM> and electric heating device according to embodiments of the present invention, the PTC heating elements <NUM> are fixed into the fixing unit <NUM> of the insulation fixing frame <NUM> respectively, so that the PTC heating elements <NUM> are stably positioned and isolated from each other by the insulation fixing frame <NUM>, thus reducing the interference among the PTC heating elements <NUM>, giving full play to the heating performance , improving the heating power and heating effect, and providing a heating source used for heating, defrosting, and defogging the interior of the electric vehicle.

In addition, the insulation fixing frame <NUM> is made of a material having a high temperature resistance and a high voltage resistance, so that the insulation fixing frame <NUM> improves the voltage resistance between the two electrode plates <NUM>, reduces the arc discharge and avoids the PTC heating elements <NUM> broken down due to the arc discharge. Thus, the PTC electric heating assemblies <NUM> and the electric heating device according to embodiments of the present invention are adapted to be used under the high voltage condition and have a high safety. Furthermore, the PTC heating module can be safely used in a high voltage system (such as the electric vehicle) for long time.

In some embodiments, as shown in <FIG> and <FIG>, a thermal conducting trough <NUM> is disposed in the casing <NUM>, the thermal conducting grooves <NUM> are formed in the thermal conducting trough <NUM>, and the medium circulating cavity <NUM> is defined between the thermal conducting trough <NUM> and an inner wall of the casing <NUM>.

In some embodiments, the casing <NUM> comprises a first shell <NUM> and a second shell <NUM> mounted on the first shell <NUM>. The thermal conducting trough <NUM> is disposed on the second shell <NUM> and extended into the first shell <NUM>. Advantageously, the thermal conducting trough <NUM> may be formed integrally with the second shell <NUM>. The medium circulating cavity <NUM> is defined between the thermal conducting trough <NUM> and an inner wall of the first shell <NUM>, and the medium inlet <NUM> and the medium outlet <NUM> are disposed in the first shell <NUM>.

In a specific embodiment, as shown in <FIG>, the first shell <NUM> is a hollow rectangular parallelepiped and made of an insulating material. A top of the first shell <NUM> is open. The first shell <NUM> comprises a bottom plate <NUM> and four side plates so as to form a receiving chamber <NUM>. The four side plates, such as a first side plate <NUM>, a second side plate <NUM>, a third side plate <NUM> and a fourth side plate <NUM>, are extended upwardly from four edges of the bottom plate <NUM> along a substantially vertical direction.

The first side plate <NUM> and the second side plate <NUM> are disposed oppositely along a length direction of the first shell <NUM> (the right and left direction shown in <FIG> and <FIG>), and the third side plate <NUM> and the fourth side plate <NUM> are disposed oppositely along a width direction of the first shell <NUM> (the up and down direction shown in <FIG>).

In order to increase flowing time and flowing distance of the medium, a distance between positions of the medium inlet <NUM> and the medium outlet <NUM> is as far as possible, for example, the medium inlet <NUM> and the medium <NUM> may be formed in two ends of the second side plate <NUM>.

The second shell <NUM> comprises an annular plate <NUM> and a skirt portion <NUM> extended downwardly from a bottom surface of the annular plate <NUM>, and the annular plate <NUM> is disposed on the top of the first shell <NUM>. The thermal conducting trough <NUM> is connected to an inner circumferential edge of a low portion of the skirt portion <NUM> and extended into the receiving chamber <NUM>. As shown in <FIG>, the thermal conducting trough has a corrugated vertical section and comprises a corrugated top plate <NUM>. Each of the thermal conducting grooves <NUM> is defined by two side isolating plates <NUM>, a front plate <NUM>, a rear plate <NUM> and a bottom plate <NUM>.

An upper portion of each of side isolating plates <NUM>, the front plate <NUM> and the rear plate <NUM> is connected to the top plate <NUM>, a lower portion of each of the side isolating plates <NUM>, the front plate <NUM> and the rear plate <NUM> is connected to the bottom plate <NUM>. Adjacent side isolating plates <NUM> of the thermal conducting grooves <NUM> are opposite to each other and spaced apart from each other so as to form circulating grooves <NUM>. As shown in <FIG>, the circulating grooves <NUM> and the thermal conducting grooves <NUM> are arranged alternately along the right and left direction.

As described above, at least one side isolating plate <NUM> of the thermal conducting grooves <NUM> may be inclined. More advantageously, both side isolating plates <NUM> of each of the thermal conducting grooves <NUM> may be inclined, and lower portions of the two side isolating plate <NUM> of each of the thermal conducting grooves <NUM> are close to each other. Correspondingly, the thickness of the electrode plates <NUM> is decreased gradually along the up and down direction as well, in other words, the two side surfaces of the PTC electric heating assembly <NUM> are inclined surfaces.

The PTC electric heating assemblies <NUM> are adapted to the thermal conducting grooves <NUM> and mounted therein. Thus, the thermal conducting grooves <NUM> isolate the medium from the PTC electric heating assemblies <NUM> and conduct the heat. The thermal conducting trough <NUM> (i.e. walls of the thermal conducting grooves <NUM>) may be made of a material having an excellent conducting performance, such as aluminum or aluminum alloy. Advantageously, the annular plate <NUM>, the skirt portion <NUM>, the top plate <NUM>, the side plates <NUM>, the front plate <NUM>, the rear plate <NUM> and the bottom plate <NUM> are made of a material having an excellent conducting performance and formed integrally into one piece.

As shown in <FIG>, the outermost circulating groove <NUM> is formed between the outermost thermal conducting groove <NUM> and the first shell <NUM>, the remaining circulating grooves <NUM> are formed between the adjacent thermal conducting grooves <NUM>. The thermal conducting grooves <NUM> are sealed relative to the circulating grooves <NUM>, so as to prevent the medium from damaging the PTC electric heating assemblies <NUM>.

In an embodiment, the circulating grooves <NUM> are communicated to each other. For example, a communicating channel <NUM> is formed by the walls of the thermal conducting grooves <NUM> and the first side wall <NUM> or the second side wall <NUM> of the first shell <NUM>. The thermal conducting grooves <NUM> are communicated via the communicating channel <NUM>, and the medium circulating cavity <NUM> defines a curved path. Thus, the medium is fed into the medium circulating cavity <NUM> via the medium inlet <NUM> and then passes through the medium circulating cavity <NUM> along the curved path, so that the passing path of the medium is lengthened, the heat absorbing time is increased and the heating absorbing efficiency is improved. Moreover, the medium flows around the thermal conducting grooves <NUM> so as to improve the heating absorbing efficiency.

As shown in <FIG>, the plurality of thermal conducting grooves <NUM> are divided into a plurality of first thermal conducting grooves <NUM> and a plurality of second thermal conducting grooves <NUM>, and the first thermal conducting grooves <NUM> and the second thermal conducting grooves <NUM> are arranged alternately.

The front plates <NUM> of the first thermal conducting grooves <NUM> are extended to the first side wall <NUM>, and the rear plates <NUM> are spaced from the second side wall <NUM>. The rear plates <NUM> of the second thermal conducting grooves <NUM> are extended to the second side wall <NUM>, and the front plates <NUM> are spaced from the first side wall <NUM>, so that the communicating channel <NUM> is formed.

The circulating grooves <NUM> are communicated to each other by the communicating channel <NUM> so as to define an S-shaped medium circulating cavity <NUM>. The medium is fed into the medium circulating cavity <NUM> via the medium inlet <NUM>, then passes through the S-shaped medium circulating cavity <NUM> along a circumferential and curved path, finally discharged from the medium outlet <NUM>. Thus, the passing path between the medium inlet <NUM> and the medium outlet <NUM> is lengthened, so that the heat absorbing time is increased and the heating absorbing efficiency is improved.

Furthermore, the medium flows around the thermal conducting grooves <NUM> so as to efficiently absorb the heat generated by the PTC electric heating assemblies <NUM> embedded into the thermal conducting grooves <NUM>, and a heat efficiency of the electric heating device is improved. In this embodiment, the number of the thermal conducting grooves <NUM> is nine, the number of the first thermal conducting grooves <NUM> is five, and the number of second thermal conducting grooves <NUM> is four. A person skilled in the art will appreciate that the number of the thermal conducting grooves <NUM>, the first thermal conducting grooves <NUM> and second thermal conducting grooves <NUM> is adjustable according to requirements.

The assembling and usage of the PTC electric device according to embodiments of the present invention will be described below.

Firstly, the PTC electric heating assemblies <NUM> is embedded into the thermal conducting grooves <NUM> by a clamp, then the second shell <NUM> is mounted to the first shell <NUM> and the first shell <NUM> and the second shell <NUM> are sealed to form the medium circulating cavity <NUM>.

In use, the medium is fed into the medium circulating cavity <NUM> through the medium inlet <NUM> of the first shell <NUM>, when the PTC electric heating assemblies <NUM> are energized, the PTC heating elements <NUM> start heating, and the heat is conducted to the medium via the electrode plates <NUM>, the insulating layer <NUM> and the thermal conducting grooves <NUM>. The medium flows out of the medium circulating cavity <NUM> through the medium outlet <NUM> of the second shell <NUM> so as to carry the heat for heating, defrosting and defogging the interior of the vehicle.

An electric vehicle according to embodiments of the present invention comprises an air-conditioning and heating system including the electric heating device described with reference to the above embodiments, and a heating exchanger coupled to the electric heating device. The medium is heated during passing through the electric heating device and then flows into the heating exchanger, such that the heat is exchanged and released to be used for heating, defrosting, defogging.

Principle of the performance test: a rated voltage was applied to the electric heating device by a high voltage power supply and the electric heating device generates heat, and a real-time current was displayed, so that the medium (such as a circulating cooling fluid) circulated inside the electric heating device was heated by the heat. Then, when the circulating cooling fluid passed through the heat exchanger, the heat carried by the circulating cooling fluid was taken away by the wind generated by a fan, therefore, the temperature of the wind was increased, but the temperature of the circulating cooling fluid was dropped. Next, the circulating cooling fluid with dropped temperature was circulated back to the electric heating device by a circulating conduit. The temperatures of fluids (including the circulating cooling fluid and the wind) were collected by a data collecting system. Test parameters: voltage: 400VDC, a flow rate of the circulating cooling fluid: <NUM>/min, a flow rate of the wind: <NUM><NUM>/h (a voltage used in lab corresponding to the fan is 12VDC), a system temperature: <NUM> ± <NUM>. Test steps: <NUM>) mounting the electric heating device for testing in a cooling fluid circulating system; <NUM>) starting the data collecting system to collect the real-time temperatures of the fluids and the environment; <NUM>) starting the fan and maintaining the flow rate of the wind at <NUM><NUM>/h; <NUM>) starting a pump and maintaining the flow rate of the circulating cooling fluid at <NUM>/min; <NUM>) maintaining the temperature of the circulating cooling fluid at a room temperature (<NUM> ± <NUM>) stably; <NUM>) setting the voltage of the high voltage power supply at 400VDC and supplying the power to the electric heating device after the temperature of the circulating cooling fluid is stable; <NUM>) reading the real-time current of the high voltage power supply and recording an inrush current (i.e. the maximum current can be reached after the high voltage power supply is turned on for about <NUM>); <NUM>) when a fluctuation of the current is less than <NUM>. 05A within <NUM> minutes, recording the stable current and stopping the test. During the test of energizing and deenergizing, the voltage of the electric heating device was 600VDC, the open and close of a high voltage circuitry was controlled by a power supply control unit, and the remaining parameters were not varied. Test results: a sample of the PTC electric heating assembly A1 was prepared according to embodiments of the present invention (a structure of the sample A1 is shown in <FIG>), a contrast sample of a conventional PTC electric heating assembly B1 was prepared. Both the sample A1 and the sample B1 were made of identical material and tested using the above test method under the above the test conditions. The only difference was that the sample B1 was not assembled with the insulation fixing frame <NUM>. The test results were as shown in Table <NUM>.

It can be seen from the results of the Table <NUM> that, the sample A1 had a higher power than the sample B1, was not broken down and has no short circuit during energizing and deenergizing test. Thus, the PTC electric heating assembly A1 according to embodiments of the present invention may improve the heating power of the PTC heating elements efficiently, have an excellent safety and be adapted to the high voltage condition by isolating and fixing the PTC heating elements via the insulation fixing frame.

The electric heating device according to embodiments of the present invention has the following advantages:.

Claim 1:
A PTC electric heating assembly comprising:
two electrode plates (<NUM>); and
a PTC heating module (<NUM>) disposed between the two electrode plates (<NUM>), and including
an insulation fixing frame (<NUM>) defining a plurality of fixing units (<NUM>),
a plurality of PTC heating elements (<NUM>) disposed in the fixing units (<NUM>) respectively;
a contact electrode (<NUM>) is disposed between the PTC heating module (<NUM>) and each of the electrode plates (<NUM>); and adhered to the insulation fixing frame (<NUM>) by an adhesive;
the contact electrode (<NUM>) is configured as a compressible conducting layer comprising a polymer and a conducting material compounded with the polymer, characterized in that the polymer in the compressible conducting layer comprises one or more selected from polyimide, PTFE, organic silicon resin and ethoxyline resin and the conducting material comprises one or more selected from metal fiber, metal particles, metal mesh, carbon and graphite.