BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 a perspective top view of a part of the embodiment with the cover open;
FIG. 2 a perspective top view of the bottom part of the housing with the housing base removed;
FIG. 3 a view of the longitudinal section through the embodiment shown in FIG. 1;
FIG. 4 a perspective top view onto an embodiment of an electric heating element which is used in the heating device according to FIGS. 1 to 3;
FIG. 5 two plates to be placed onto the part shown in FIG. 1;
FIG. 6 the embodiment according to FIG. 1 with plates according to FIG. 5 set onto the part;
FIG. 7 the embodiment according to FIG. 1 with the second printed circuit board placed upon it; and
FIG. 8 the embodiment shown in the preceding figures with the cover placed upon it.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 shows the embodiment of a heating device 2 with an elongated housing 4, consisting of an essentially cylindrical housing frame 4 and a housing base 4b screwed to it. Connecting pieces are arranged on a lateral surface of the housing frame 4a, on opposite ends of this elongated housing frame 4a, whereby these connecting pieces surround inlet and outlet openings 6, 8, whereby connection lines can be connected to these connection pieces via hose clips or the like, and whereby these connection lines lead to a circulation chamber 10 that is essentially surrounded by the housing frame 4a. In FIG. 1, the connecting pieces are arranged on the frontal ends of the housing frame 4a. Another arrangement of the connecting pieces on the opposing ends of the elongated housing frame 4a is indicated by dashed lines. This circulation chamber 10 is separated from a heating chamber 14 above it by a separating wall 12, namely in such a way that the fluid (for example, water) contained in the circulation chamber 10 cannot reach the heating chamber 14. The separating wall 12 can, for example, be formed on to the housing frame 4a as a single piece.
As FIG. 3 illustrates, the separating wall 12 forms a number of recesses 16 arranged one behind the other along the width, whereby these recesses 16 essentially extend across the entire length of the housing 4 (cf. FIG. 2). The separating wall 12 accordingly has a meandering shape with recesses 16 that project deeply into the circulation chamber 10, which recesses are completely sealed off from the circulation chamber 10 and open to the heating chamber 14. Because these recesses 16 are preferably manufactured from a material that is a good conductor, particularly metal and, in this case, especially aluminium, manufacturing the separating wall 12 as, for example, a separate component by means of shaping suggests itself. The recesses 16 have a U-shaped cross-section and run along the length of the housing 4, parallel to one another.
Heating elements 18, which have the design shown in FIG. 4, are located in each of the recesses 16. The exterior side of each of the heating elements 18 is formed by ceramic plates 20. A number of PTC heating elements 22 are arranged between these ceramic plates here. Contact plates 24 made of an electrically conducting material are, in turn, located between these PTC heating elements 22 and the ceramic plates 20. Extension sections 26 are formed on to these contact plates 24 as a single piece. The extension sections 26 of the contact plates which lie opposite one another are located on diagonally opposing sides. The extension sections are accordingly spaced apart from one another not only on the basis of the thickness of the PTC heating elements 22 but furthermore also essentially by the width of the heating elements 18. For reinforcement, the extension sections 26 are doubled by folding the material of the contact plates 24 one time in the thickness.
The ceramic plates 20, the PTC heating elements 22 and the contact plates 24 are preferably combined into one unit by means of gluing. As FIG. 4 illustrates, the ceramic plates 20 project beyond the PTC heating elements 22 and the contact plates 24 on all sides, forming an edge around the circumference. The heating elements 18 introduced into the recesses 16 lie on a side piece 28 of the U-shaped recess 16 with one of the ceramic plates 20. Between the opposing side piece 30 and the heating unit 18 is a pressure element 32, which is introduced into the recess 16 under tension and which is assigned to a single electric heating element 18. The respective pressure element 32 holds a single heating element 18 in the recess 16 and braces it against the opposing side pieces 28, 30 of the recess 16. The heating element 18 accordingly lies against the opposing side pieces 28, 30 with good heat conduction. Furthermore, the heating elements 18 stand up on a tab 34 of the recess 16, said tab 34 connecting the side pieces 28, 30, so that the heating elements 18 are accordingly fixed with respect to the height. The electric heating element 18 lies, with the lower face sides of the ceramic plates 20, on the tab 34, so that the electrically conducting parts of the heating element 18 are spaced at a distance from the metallic tab 34 and consequently insulated. The depth of the recesses 16 is furthermore selected in such a way that the medium in the circulation chamber 16 flows around the heating element 18 at least above the height of the PTC heating elements 22 that are stacked one on top of the other, i.e., the entire electric heating element 18 is held in the recess 16.
The U-shaped recesses 16 have a slightly conically tapered cross-section. The pressure element 32 is likewise formed in a wedge-shape, namely, with a pitch corresponding to the conical progression of the recess 16. The thickness of the pressure element 32 and the electric heating element 18 essentially corresponds to the width of the respective recess 16.
The pressure element 32 consists of a good thermally conducting material, for example, aluminium, and the thickness of the ceramic plates 20 is selected in such a way that the heat conduction from the heating elements 18 is scarcely interfered with by the material of the side pieces 28, 30. Because of the high degree to which the heating elements 18 are pressed together with the pressure element 32, the heat dissipation to the two sides of the elongated recesses 16 is virtually symmetrical.
As can be seen in FIG. 1, the extension sections 34 project beyond the upper side of the separating wall 12 and lie freely in the heating chamber 14. The plates shown in FIG. 5, namely an insulating plate 35 and a first printed circuit board 36, are slid on to these extension sections 26. The insulating plate 35 is made from an electrically insulating material and has a hole pattern corresponding to the size and position of the extension sections. The openings cut into the insulating plate 35 for the extension sections 26 serve to guide the extension sections 26 and to ensure insulation. Furthermore, the insulating plate 35 has recesses and receptacles for parts of the first printed circuit board 36 that protrude from the first printed circuit board 36.
The first printed circuit board 36 has two contact receptacles 38 for each recess 16, whereby said contact receptacles 38 are formed by bent and pre-tensed extension section receptacles 40 that hold the extension sections 26 (cf. particularly FIG. 3). In an alternative development, not shown here, the contact receptacles can also be formed by two opposing contact plates, whose clear spacing is selected in such a way that the extension sections held in the contact receptacles lie against the contact plates with an initial tension. In such a case, a number of extension sections of electrical elements arranged one behind the other are connected in series via the contact plates. In the embodiment shown, the electrical grouping of heating elements 18 is produced by the strip conductors of the first distributor plate 36, which is accordingly also indicated as a printed circuit board.
Six tab elements 41 and a cylindrical connecting element 42 for the positive phase project beyond the first printed circuit board 36 on the upper side facing away from the heating elements 18, whereby each projection is arranged on the first printed circuit board 36. The first printed circuit board 36 lies approximately at the height of the supporting surfaces 43 that are provided on the frontal ends of the housing frame 4a. The first printed circuit board 36 has no electronic components, but instead only strip conductors and the previously mentioned connecting elements 41, 42, and consequently the first printed circuit board 36 serves only to combine individual electric heating elements 18 into groups, with a view to the control of all electric heating elements in a group.
The second printed circuit board 37 has six plug-in contact receptacles 44 assigned to the contact stud elements 41, whereby these plug-in contact receptacles 44 are arranged on the upper side of the second printed circuit board 37. Furthermore, a negative connecting element 45 is provided on the upper side of the second printed circuit board 37. On its underside, the second printed circuit board 37 carries electric switching elements, particularly semiconductor switches 46 which project beyond the second printed circuit board 37 frontally or at the end and, with an insulating layer 47 placed in between, lie against the supporting surfaces 43 so that, because of the direct contact created in this way, it is possible to dissipate lost heat generated by the semiconductor switches 46 by conducting it into the housing 4, seeing that the second printed circuit board 37 is mounted at a distance to the first printed circuit board 36. The contact stud elements 41 then engage in the corresponding plug-in contact receptacles 44. The positive connecting element 42 protrudes through a recess cut into the second printed circuit board 37 and projects beyond the second printed circuit board 37. The subsequent contacting takes place on the two connecting elements 42 and 45 when a housing cover 48 is placed in position. This cover has a power terminal 50 and a signal terminal 52 on its upper side and serves to seal the heating chamber 14 off from the surroundings.
The embodiment shown in the drawing has 24 heating elements, each with four PTC heating elements and, surprisingly, it has been seen that this electric heating device can deliver thermal heat output of more than 10 kW. With this output, the energy of an electric drive created by the generator operation that cannot be stored can be converted into thermal energy via the heating device.
Patent Application
20080000889
