Heat medium heating apparatus and vehicular air-conditioning system including the same

Abstract

Provided is a heat medium heating apparatus including: a plurality of flat heat exchanger tubes 12; PTC heaters 13 that are respectively incorporated between flat tube parts of the flat heat exchanger tubes 12; a heat exchanger holding member 15 that press-fixes the flat heat exchanger tubes 12 and the PTC heaters 13, from one side of the flat heat exchanger tubes 12 to an inner surface of a casing 11; and a control board 17 that has a surface on which a control circuit 21 is mounted, the control circuit 21 including heat-generating electrical components 20 that control the PTC heaters 13, in which the control board 17 includes heat penetration parts that are formed so as to pass through the control board 17 correspondingly to mounting positions of the heat-generating electrical components 20, and the heat-generating electrical components 20 are mounted so as to be cooled via the heat penetration parts.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based on Japanese Patent Application No. 2011-060927, the contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a heat medium heating apparatus that heats a heat medium using a positive temperature coefficient heater and a vehicular air-conditioning system including the heat medium heating apparatus.[0004]2. Description of Related Art[0005]Vehicular air-conditioning systems applied to an electric car, a hybrid car, and other such cars are generally provided with a heat medium heating apparatus that heats a medium to be heated serving as a heat source for heating equipment, and one of such heat medium heating apparatuses is known to heat a medium using a positive temperature coefficient heater (hereinafter referred to as PTC heater) including a positive temperature coefficient thermistor (hereinafter referred to as PTC elem...

AI Technical Summary

Benefits of technology

[0013]According to the present invention, the plurality of flat heat exchanger tubes are stacked on each other, and the PTC heaters are respectively incorporated between the flat tube parts thereof. In this state, the flat heat exchanger tubes and the PTC heaters are pressed by the heat exchanger holding member, to be thereby brought into close contact with each other. The control board having the surface on which the control circuit is mounted is placed above the heat exchanger holding member, the control circuit including the heat-generating electrical component that controls the PTC heaters. The control board includes the heat penetration part that is formed so as to pass through the control board correspondingly to the mounting position of the heat-generating electrical component, the heat penetration part being made of the highly thermally conductive material, and the heat-generating electrical component is mounted so as to be cooled via the heat penetration part by the heat exchanger holding member functioning as the heat sink. Hence, the PTC heaters are respectively sandwiched and stacked between the plurality of flat heat exchanger tubes, and the flat heat exchanger tubes and the PTC heaters are pressed by the heat exchanger holding member. As a result, the flat heat exchanger tubes and the PTC heaters can be incorporated in close contact with each other. Accordingly, the thermal contact resistance between the flat heat exchanger tubes and the PTC heaters can be reduced, and the heat transfer efficiency can be increased, so that the performance of the heat medium heating apparatus can be enhanced. Further, because the flat heat exchanger tubes and the PTC heaters are stacked into a multilayer structure, the planar area thereof can be reduced, and the heat exchanger module and even the heat medium heating apparatus can be compactified. In addition, because the control board is provided above the heat exchanger holding member that presses the flat heat exchanger tubes from one side thereof, the heat-generating electrical component mounted on the control board can be efficiently cooled via the heat penetration part by the heat exchanger holding member functioning as the heat sink. Accordingly, easy incorporation of the control board and the reliability thereof against heat can be ensured, and the need to provide a dedicated board accommodating box and a large-sized heat medium circulating box can be eliminated, leading to a reduction in size and weight of the heat medium heating apparatus as well as lower costs thereof.

[0015]According to the present invention, the heat exchanger holding member is made of the aluminum alloy plate. Therefore, heat from the heat-generating electrical component on the control board is transferred through the heat penetration part to the heat exchanger holding member made of the light aluminum alloy plate having excellent thermal conductivity, and the heat is then transferred to the heat exchanger holding member cooled by the flat heat exchanger tubes, whereby the heat-generating electrical component can be cooled. Accordingly, the cooling performance of the heat-generating electrical component mounted on the surface of the control board can be enhanced by the heat exchanger holding member functioning as the heat sink, the reliability against heat can be increased, and the reduction in weight can be retained.

[0017]According to the present invention, the spacer member is interposed between the heat exchanger holding member and the heat penetration part of the control board, the spacer member being made of the highly thermally conductive material and having the predetermined thickness. Therefore, when the control board is placed above the heat exchanger holding member, even if a given interval therebetween needs to be ensured, the spacer member made of the highly thermally conductive material such as an aluminum alloy plate and having the predetermined thickness is interposed therebetween, whereby the heat exchanger holding member can function as the heat sink to thereby reliably cool the heat-generating electrical component mounted on the surface of the control board. Accordingly, even in such a case, the cooling performance for the control board can be enhanced, the reliability against heat can be ensured, and the reduction in weight can be retained.

[0019]According to the present invention, the plurality of terminal blocks are arranged along one side of the surface of the control board, and the plurality of terminals extending from one ends of electrode plates provided on both the surfaces of the PTC heaters are respectively connectable directly to the terminal blocks. Therefore, the control board having the surface on which the control circuit including the heat-generating electrical component that controls the PTC heaters is mounted can be electrically connected to the electrode plates provided on both the surfaces of the PTC heaters, by respectively connecting, on the surface side of the control board, the terminals extending from the one ends of the electrode plates directly to the terminal blocks arranged along the one side of the surface of the control board. Accordingly, the work of electrically connecting the control board to the electrode plates can be facilitated, and the assembling properties can be thus improved. Further, the need to provide a harness is eliminated, leading to a reduction in the number of components, more simplified configuration, and lower costs.

[0021]According to the present invention, the plurality of flat heat exchanger tubes and the PTC heaters in the alternately stacked state are fastened to the inner bottom surface of the casing by the heat exchanger holding member, the casing including the heat medium inlet and the heat medium outlet respectively communicated with the inlet header part and the outlet header part. Therefore, the flat heat exchanger tubes and the PTC heaters alternately stacked on each other are fastened to the inner bottom surface of the casing by the heat exchanger holding member, whereby the flat heat exchanger tubes and the PTC heaters can be fixed in close contact with each other. Accordingly, the flat heat exchanger tubes and the PTC heaters can be stacked on each other such that the close contact therebetween is easily and reliably increased in the course of the stacking. Hence, the thermal contact resistance between the flat heat exchanger tubes and the PTC heaters can be reduced, the heat transfer performance can be thus increased, and the assembling properties can be improved. In addition, the casing does not necessarily need to be made of an aluminum alloy material having a heat resistance property and a heat transfer property, and may be made of a resin material, leading to a reduction in weight as well as lower costs.

[0023]According to the present invention, the heat medium heated by the heat medium heating apparatus having any of the above-mentioned features can circulate through the heat radiator placed in the air flow passage. Therefore, the heat medium to be supplied to the heat radiator provided in the air flow passage can be heated by the heat medium heating apparatus having the reduced size, the reduced weight, and the enhanced performance as described above. Accordingly, the air-conditioning performance, particularly, the heating performance of the vehicular air-conditioning system can be enhanced, and the mounting properties of the air-conditioning system onto a vehicle can be enhanced.

Problems solved by technology

Therefore, it is not easy to respectively insert and set the PTC heating elements between the separating walls serving as heat transfer surfaces so as to bring the PTC heating elements into close contact therewith.

Meanwhile, if the intervals between the separating walls are narrowed in order to obtain closer contact, the workability of incorporating the PTC heating elements remarkably decreases, resulting in an increase in man-hours.

However, because it is difficult to stack the PTC heaters into a multilayer structure, the planar area thereof increases, and the heat medium circulating boxes and the dedicated board accommodating box need to be provided.

These boxes are made by aluminum die casting in view of a heat resistance property, a heat transfer property, and other such properties, resulting in a limited reduction in size and weight as well as high costs.

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