EP3310126A1

EP3310126A1 - High voltage air heater and method for the assembly of its heating elements

Info

Publication number: EP3310126A1
Application number: EP16193318.9A
Authority: EP
Inventors: Sam Huang
Original assignee: DBK David and Baader GmbH
Current assignee: DBK David and Baader GmbH
Priority date: 2016-10-11
Filing date: 2016-10-11
Publication date: 2018-04-18

Abstract

Disclosed is a high voltage air heater comprising pre-installed heater steps which each comprise a middle component and two outer lamella elements. The heater steps further comprise a frame and are fastened at a distance to each other via a respective end portion and via a respective rotatable locking ring to a control housing of the high voltage air heater. In the control housing, high voltage switching elements are, by a respective clamp element, clamped against a respective heat dissipation element, wherein the arrangement of voltage switching element, clamp element, and heat dissipation element is disposed at a common side of a printed circuit board assembly.

Description

The invention relates to a high voltage air heater in accordance with the preamble of claim 1 and to a method for the assembly thereof.
With air heaters, for instance, for heating the air of vehicle passenger compartments it is known to dissipate the heat of energized PTC elements via lamella elements to the air which is guided through the lamella elements and then into the vehicle passenger compartment. PTC elements have a positive temperature coefficient and are therefore self-regulating PTC thermistors building up increasing electrical resistance with increasing heat, so that the electrical power input and hence also the heating power are reduced.
Documents EP 1 327 834 B1 and EP 1 445 553 A1 each disclose such air heaters for vehicles in which several heat-generating PTC elements are arranged in elongate housings which are in turn in close succession in contact with the heat-dissipating elongate lamella elements. Disadvantages of such air heaters are their adaptability for low voltages and their limited power.
Document EP 2 608 633 A1 discloses a high voltage air heater in which the housings with the PTC elements and the lamella elements are also in contact with each other in close succession and thus form a cuboidal throughflowable block enclosed in a correspondingly cuboidal frame. A housing with electric contacts is provided at one of the two shorter front sides of the frame.
The disadvantage of such high voltage air heaters is that the assembly of the lamella elements and of the housings with the PTC elements, due to their layering and enclosure in the frame, causes much effort with respect to device technology and assembly technique.
Compared with this it is an object of the invention to provide a high voltage air heater and a method for the assembly thereof in which the disadvantages mentioned are reduced or avoided.
This object is solved by a high voltage air heater with the features of claim 1 and by a method for the assembly thereof with the features of claim 14.
The claimed high voltage air heater comprises several elongate components referred to as step cores which each accommodate several PTC elements. The PTC elements serve to convert current to heat and, for this purpose, can be energized via a control housing and the components. The heat of the PTC elements can be dissipated indirectly to the air. In accordance with the invention each component is, by a locking ring arranged at the end portion, directly or indirectly fastened to the control housing. Thus, it is possible to omit the frame of the state of the art, and the high voltage air heater is simplified with respect to device technology and assembly technique.
High voltage means in the scope of this document at least 100 Volt, preferably at least 500 Volt.
Depending on the assembly or operating concept, the locking ring may be rotatable and/or displaceable in a translatory manner relative to the end portion. A bayonet lock is particularly preferred. The locking ring can also be different from bayonet lock, for example a screwed ring.
Further advantageous developments of the invention are described in the dependent claims.
In a preferred embodiment several approximately circular cylindrical coupling projections are arranged at the control housing, which, in the assembled state, are each encompassed at least in sections by a locking ring.
In a further development respective retaining webs directed radially outwardly are formed at the outer circumference of the coupling projections; in the mounted state, they are engaged behind by a respective retaining web of the locking ring which is directed radially inwardly.
Preferably, the retaining webs have the shape of a circular arc. For an even transmission of the retaining and/or clamping force on both sides, always two retaining webs opposing each other may be provided at the coupling projections and at the locking rings.
For sealing the electrically operated PTC elements from the ambient air to be heated, e.g. from the condensed water thereof, it is preferred if an axial sealing element each is provided between the coupling projections and the respective end portions of the components or their frames.
In order to improve the sealing further, a radial sealing element each may additionally be provided between the coupling projections and the respective end portions of the components or their frames.
The locking rings are easy to operate if a respective profiling is provided at the outer circumferences thereof.
A respective preferred locking ring has an anti-twist protection for securing the assembly and/or fastening of the corresponding component or its frame at the control housing. Thereby a precise mechanical pressure of the sealing elements (especially the axial sealing elements) should be realized.
A respective bayonet lock between the control housing and the respective end portion is preferred, wherein the bayonet lock has the anti-twist protection for securing the assembly and/or fastening of the corresponding component or its frame at the control housing.
An axial corrugation is preferred as a profiling, wherein the anti-twist protection comprises a lug or tongue which is fastened to the control housing and which is engageable with the axial corrugation. Thus, the profiling is simple and effective with respect to production technology while the anti-twist protection is simple with respect to device technology and secure at the same time.
In the interior of each locking ring preferably two terminal tabs are arranged which extend approximately axially to the locking ring. Thus, it is possible to insert the associated component in a translatory manner into the control housing or into the corresponding coupling projection and to electrically contact the terminal tabs in the interior thereof.
Preferably the locking ring projects above the two terminal tabs for their protection.
In a preferred embodiment of the high voltage air heater in accordance with the invention each component has two outer surfaces to which a lamella element each is fastened in a heat-conducting manner - preferably glued. Thus, pre-assembled heater steps have been formed which are fastened to the control housing via the respective locking ring.
For reasons of stability it is preferred if the heater steps comprise a respective support and/or clamping frame which encompasses the respective component, preferably clamps it. The respective locking rings are then arranged at the end portions of the frames, and the end portions of the frames are fastened to the control housing.
The frames preferably define a respective frame plane which, for the purpose of flow optimization, is always oriented perpendicular to the throughflow direction.
In a preferred further development the heater steps are arranged at a distance to each other. Thus, the air resistance of the high voltage air heater in accordance to the invention is reduced during throughflowing as compared to the state of the art and/or the lamella elements are electrically decoupled from each other if they are energized.
The heater steps are preferably arranged inside and at the same time spaced apart from a main body housing. This serves, for instance, to protect the lamella elements.
The method in accordance with the invention serves the assembly of the above-described high voltage air heater, wherein the assembly or fastening of the components (step cores) or their frames at the control housing comprises the following steps in the order mentioned:

moving of the end portion over the associated coupling projection, and
rotating of the locking ring, preferably about approximately 90 degrees.

Preferably, before or during rotating of the locking ring sealing of the component is performed by clamping the axial seal between the end portion and the coupling projection.
An embodiment of the high voltage air heater in accordance with the invention is illustrated in the Figures. The invention will now be explained in detail by means of the Figures.
There show:

Figure 1 the embodiment of the high voltage air heater in accordance with the invention in a perspective view,
Figure 2 the embodiment of figure 1 in an exploded view,
Figure 3 the embodiment of figure 1 in a further exploded view,
Figure 4 the embodiment of figure 1 in plan view,
Figure 5 a section of the embodiment of figure 1 in longitudinal section,
Figure 6 a heater step of the embodiment of the high voltage air heater of figure 1 in a perspective view,
Figure 7 the heater step of figure 6 in an exploded view,
Figure 8 the heater step of figure 6 in a perspective cross-section,
Figure 9 the assembly of a locking ring of the heater step of figure 6 in four perspective individual views,
Figure 10 the assembled locking ring of figure 9 in a perspective sectional view, and
Figures 11 to 14 the high voltage air heater with an open control housing in perspective views.

Figure 1 shows the embodiment of the high voltage air heater in accordance with the invention in a perspective view. It comprises a main body housing 1 which is covered by an approximately two-dimensional main body housing cover 2. Thus, an approximately cuboidal interior is formed which will be explained in detail with reference to the further figures.
A likewise approximately cuboidal control housing 4 which is covered by a control housing cover 6 is fastened to the front side of the main body housing 1. The two parts 4, 6 are formed as two shell parts, with the control housing 4 being larger than the control housing cover 6. At the two front sides of the control housing 4 a screw fixation 12 each is formed integrally; only one screw fixation 12 thereof is illustrated in the figure. An electronic arrangement in the interior of the control housing 4 is energized by a power cable 8 and controlled by a signal wire 10.
In operation the high voltage air heater in accordance with the invention is placed in an airflow which is directed approximately perpendicular to the main body housing cover 2 and which is guided into the interior of an electrically driven vehicle. The high voltage air heater is fixed by the two screw fixations 12 and is energized via the power cable 8 with a voltage of e.g. 350 Volt from the on-board electrical system of the vehicle.
Figure 2 illustrates the high voltage air heater of figure 1 in an exploded view. In the interior of the main body housing 1 six elongate heater steps 14 are arranged spatially in parallel to each other, by which the current is electrically converted to heat and which will be explained in detail with reference to the following figures. Each heater step 14 is, with its end portion (positioned at the left in figure 2), connected with the control housing 4 through a bayonet lock. Each bayonet lock has a coupling projection 16 formed integrally with the control housing 4 and a locking ring 18 positioned at the respective heater step 14, wherein the bayonet lock will be explained in detail with respect to the following figures. Furthermore, figure 2 illustrates that a printed circuit board assembly 20 which the power cable 8 is connected to via two connections 22 is accommodated in the interior of the control housing 4.
From the control housing 4, pivots 24 which are distributed evenly at the rim extend in the direction to the control housing cover 6. In the assembled state of the control housing 4 these pivots 24 penetrate respective through-recesses 26 of the control housing cover 6, and the end portions of the pivots 24 are welded or shaped with the control housing cover 6.
Figure 2 further illustrates that the main body housing 1 and the main body housing cover 2 are each penetrated by a plurality of hexagonal through-recesses 28 through which the airflow to be heated is guided.
The main body housing 1 and the main body housing cover 2 can be connected with each other by means of clips or by welding or shaping. According to figure 2, pivots 29 are distributed evenly at the rim of the main body housing cover 2 and extend in the direction to the main body housing 1 to be welded or shaped there.
Figure 3 illustrates the high voltage air heater according to the preceding figures in a further exploded view. The changed perspective reveals a first side of the printed circuit board assembly 20 which faces the heater steps 14 and at which three high voltage switching elements 30 are arranged at a distance to the printed circuit board assembly 20. The high voltage switching elements 30 are in contact with a respective heat dissipation element 32 manufactured of aluminum or copper, wherein only respective groups of cooling ribs 34 of the heat dissipation elements 32 are illustrated in figure 3. They project through the control housing 4 into the main body housing 1 and are arranged between always two coupling projections 16.
In accordance with figure 2 three respective openings 36 are provided in each the main body housing 1 and the main body housing cover 2, said openings 36 being arranged pairwise before and behind the groups of cooling ribs 34 such that the high voltage switching elements 30 dissipate their heat via the heat dissipation elements 32 and further via their respective group of cooling ribs 34 to the airflow, so that the high voltage switching elements 30 are optimally cooled and thus contribute to the heating of the airflow.
Furthermore, in figures 2 or 3, each in the main body housing 1 and in the main body housing cover 2 six through-recesses 38 are illustrated which are also positioned pairwise consecutively in the flow direction. The through-recesses 38 serve to cool connection points between the heater steps 14 and respective electric connections (crimp places) to the printed circuit board assembly 20.
Figure 4 shows a plan view of the control housing cover 6.
Figure 5 shows a longitudinal section according to the section plane A-A of figure 4 through a part of the high voltage air heater in accordance with the invention. More precisely, the control housing 4 and a part of the main body housing 1 are illustrated.
Each of the six heater steps 14 has two terminal tabs, wherein only one respective terminal tab 40 thereof is illustrated in figure 5. Two equally polarized terminal tabs 40 of two different heater steps 14 are each electrically connected with a joint electric contact 44 of the printed circuit board assembly 20 via respective crimp places and a joint (basically y-shaped) electric conductor 42. Of the total of six electric conductors 42 only three end portions are illustrated which are plugged into associated electric contacts 44 of the printed circuit board assembly 20. Thus, two heater steps 14 are each energized jointly and equally. The printed circuit board assembly 20 enables that the heating power of each pair of heater steps 14 is selected and controlled finely.
Due to the pairwise grouping of always two heater steps 14 only three high voltage switching elements 30 are required which are illustrated in section in the figure along with a respectively associated heat dissipation element 32. Moreover, three respective pins 46 of the high voltage switching elements 30 can be recognized which extend at an angle in parallel to the section plane of figure 5 and the end portions of which are inserted in corresponding recesses of the printed circuit board assembly 20 and are soldered there.
Figure 6 illustrates a heater step 14 with its circumferential frame 48 at the end portion of which the locking ring 18 is arranged rotatably.
Figure 7 illustrates the heater step 14 of figure 6 in an exploded view. The frame 48 is formed of a circumferential step housing 50 and a likewise circumferential step housing cover 52. The locking ring 18 is attached rotatably at the step housing 50.
The step housing 50 and the step housing cover 52 clamp a series of PTC elements 54 in a component formed of two cover plates 60. More precisely, the PTC elements 54 are clamped between two contact plates 56 to which the two terminal tabs 40 (mentioned with reference to figure 5) are also fastened. Outside of the two contact plates 56 respective insulation plates 58 are provided, at the outer sides of which in turn a respective one of the two cover plates 60 is arranged. Respective lamella elements 62 are glued to the outer sides of the two cover plates 60 and thus to the two outer sides of the component.
These lamella elements 62 are folded and/or bent from a long metal strip, so that a plurality of two-dimensional fins are formed which extend substantially away from the cover plates 16 and hence also away from the component of the heater steps 14 so as to be able to dissipate the heat of the PTC elements 54 optimally to the air.
Figure 8 illustrates a perspective sectional view of one of the heater steps 14, six of which have been incorporated in the embodiment of the high voltage air heater in accordance with the invention according to the preceding figures.
As was explained with reference to figure 7, the PTC elements 54 are contacted electrically on both sides via the respective contact plate 56. At the outer sides thereof the two insulation plates 58 and the two cover plates 60 are arranged, wherein, at the outwardly facing surfaces of the cover plates 60 to which also the respective lamella element 62 is glued, retaining grooves 66 are provided into which respective projections 68 of the step housing 50, on the one hand, and of the step housing cover 52, on the other hand, are inserted.
The connection of the step housing 50 with the step housing cover 52 is performed via projections 70 distributed on the outer circumference of the thus-formed frame 48, which are inserted in corresponding through-recesses 72 and are secured and connected there by means of welding, e.g. ultrasonic welding or by shaping.
In order to seal the energized inner region of the heater step 14 and/or its component from moisture, a respective seal 73 is arranged between the (in figure 8 upper) cover plate 60 and the step housing cover 52 and between the (in figure 8 lower) cover plate 60 and the step housing 50. Finally, a seal 75 is also arranged between the step housing 50 and the step housing cover 52. The three seals 73, 75 and the frame 48 consisting of the step housing 50 and the step housing cover 52 are approximately rectangular and elongate and comprise the entire component of the heater step 14.
Figure 9 illustrates (in a succession of four individual views from the left to the right) the assembly and/or fastening of the heater step 14 and/or its frame 48 to the control housing 4 through the bayonet lock. The bayonet lock has, on the one hand, an approximately circular cylindrical coupling projection 16 which is formed integrally on the control housing 4 and, on the other hand, a rotatable locking ring 18 which is arranged on the frame 48. The coupling projection 16 has two semicircular retaining webs 74 opposing each other and directed radially outwardly, while the locking ring 18 comprises correspondingly two semicircular retaining webs 76 opposing each other and directed radially inwardly. Each retaining web 74, 76 extends over somewhat less than 90 degrees at the circumference of the corresponding component 16, 18. An axial corrugation is provided at the outer circumference of the locking ring 18 such that, during assembly and electric contacting of the heater step 14 at the control housing 4, the locking ring 18 is first of all shifted in axial direction over the coupling projection 16 and then locked by a rotation about approximately 90 degrees.
In the interior of the locking ring 18 the terminal tabs 40 (which are hidden in figure 9) extend (cf. figure 7). In order to seal them and other energized components in the interior of the coupling projection 16 from moisture, a radial sealing element 78 is inserted in a groove at the outer circumference thereof.
Figure 10 illustrates in a perspective, partially sectional view in particular the interior of the coupling projection 16, wherein the frame 48 of the heater step 14 is fastened to the control housing 4 through the bayonet lock. In this process, the retaining webs 76 of the locking ring 18 engage behind the retaining webs 74 of the coupling projection 16. For sealing, an axial sealing element 79 is, beyond the radial sealing element 78 mentioned with reference to figure 9, clamped between a front side of the coupling projection 16 and a corresponding contact of the frame 48. The locking ring 18 comprises an anti-twist protection which is formed by an axial corrugation at the outer circumference of the locking ring 18 and of a lug 81 which is fastened to the control housing 4 and snaps into the corrugation. One of the two terminal tabs 40 and the electric contacting thereof is illustrated in the interior of the coupling projection 16.
Figure 11 illustrates the high voltage air heater and/or in particular the opened control housing 4 in a perspective view. For each heater step 14 (which is not illustrated in detail in figure 11) the two terminal tabs 40 and their electric contacting can be recognized. Due to the pairwise grouping of the heater steps 14 only three high voltage switching elements 30 are required which are each illustrated in the state not yet assembled, while the respective associated heat dissipation elements 32 are already assembled in the interior of the control housing 4.
Each heat dissipation element 32 has a contact face 80 which is surrounded by a rim 82. The rim 82 is in a so-called shifting direction (which runs from the left to the right in figure 11) larger than the associated voltage switching element 30.
Furthermore, a total of six electric contacts 44 are illustrated in figure 11, which have already been explained with reference to figure 5.
Figure 12 illustrates the high voltage switching elements 30 in their state in contact with the contact face 80 of the heat dissipation elements 32. Furthermore, three clamp elements 84 are illustrated which are manufactured of spring steel sheet and by which the high voltage switching elements 30 are clamped against the contact faces 80. For this purpose the clamp elements 84 encompass the high voltage switching elements 30 and engage with their respective lugs 86 behind the contact faces 80.
Figure 13 illustrates the assembled state of the clamp elements 84 by their clamping the high voltage switching elements 30 against the (in figure 13 underlying) heat dissipation elements 32.
The heat dissipation elements 32 with the high voltage switching elements 30 and the clamp elements 84 are positioned in an (in figure 13 lower) area of the control housing 4 which faces the heater steps 14. In this area the electric conductors 42 (mentioned with reference to figure 5) are also used, which - as already explained - electrically connect always two terminal tabs 40 of two different heater steps 14 jointly with one of the electric contacts 44.
Figure 14 illustrates an assembly state of the electronics in the interior of the control housing 4 which follows the one of figure 13. The printer circuit board assembly 20 is placed in the control housing 4 and electrically connected with the electric contacts 44 by which it is also retained mechanically. Thus, the heat dissipation elements 32 with the high voltage switching elements 30 and the clamp elements 84 are all arranged at a first side (in figure 14 beneath) of the printed circuit board assembly 20. At a second side (which is visible in figure 14) of the printed circuit board assembly 20 which is opposite to the first side, the power cable 8 with the two connections 22 and the signal wire 10 are arranged. The control housing cover 6 (cf. figure 4) is finally fitted over the pivots 24.
Disclosed is a high voltage air heater comprising pre-assembled heater steps which each comprise a middle component and two outer lamella elements. The heater steps further comprise a frame and are fastened at a distance to each other via a respective end portion and via a respective rotatable locking ring to a control housing of the high voltage air heater. In the control housing, high voltage switching elements are, by a respective clamp element, clamped against a respective heat dissipation element, wherein the arrangement of voltage switching element, clamp element, and heat dissipation element is disposed at a common side of a printed circuit board assembly.

List of reference signs

1: main body housing
2: main body housing cover
4: control housing
6: control housing cover
8: power cable
10: signal wire
12: screw fixation
14: heater step
16: coupling projection
18: locking ring
20: printed circuit board assembly
22: connection
24: pivot
26: through-recess
28: through-recess
29: pivot
30: high voltage switching element
32: heat dissipation element
34: group of cooling ribs
36: opening
38: through-recess
40: terminal tab
42: electric conductor
44: electric contact
46: pin
48: frame
50: step housing
52: step housing cover
54: PTC element
56: contact plate
58: insulation plate
60: cover plate
62: lamella element
64: fin
66: retaining groove
68: projection
70: projection
72: through-recess
73: seal
74: retaining web
75: seal
76: retaining web
78: radial sealing element
79: axial sealing element
80: contact face
81: lug
82: rim
84: clamp element
86: lug

Claims

A high voltage air heater comprising several elongate components which each accommodate several PTC elements (54) and which can be energized via a control housing (4), wherein the heat of the PTC elements (54) can be dissipated to the air, characterized in that each component is fastened to the control housing (4) by a locking ring (18) arranged at the end portion of the respective component.
The high voltage air heater according to claim 1, wherein several approximately circular cylindrical coupling projections (16) are arranged at the control housing (4), whereby the coupling projections (16) are encompassed at least in sections by a respective locking ring (18).
The high voltage air heater according to claim 2, wherein at the outer circumference of the coupling projections (16) respective retaining webs (74) are formed which are directed radially outwardly and which are engaged behind by a respective retaining web (76) of the locking ring (18) which is directed radially inwardly.
The high voltage air heater according to claim 2 or 3, wherein an axial sealing element (79) each is provided between the coupling projections (16) and the end portions of the components.
The high voltage air heater according to any of claims 2 to 4, wherein a radial sealing element (78) each is provided between the coupling projections (16) and the respective end portions of the components.
The high voltage air heater according to any of the preceding claims, wherein a profiling is provided at the outer circumference of the locking ring (18).
The high voltage air heater according to any of the preceding claims, wherein the locking rings (18) form a respective bayonet lock with anti-twist protection between the control housing (4) and the respective end portion of the component.
The high voltage air heater according to claims 6 and 7, wherein the profiling is an axial corrugation, and wherein the anti-twist protection comprises a lug (81) fastened to the control housing (4) and engageable with the profiling.
The high voltage air heater according to any of the preceding claims, wherein two terminal tabs (40) which extend approximately axially to the locking ring (18) are arranged at least in sections in the interior of each locking ring (18).
The high voltage air heater according to any of claims 2 to 5 and according to claim 9, wherein the two terminal tabs (40) are inserted at least in sections in the associated coupling projection (16) and are electrically connected in the interior thereof.
The high voltage air heater according to any of the preceding claims, wherein each component has two outer surfaces to which a lamella element (62) each is fastened, thus forming heater steps (14) which are fastened to the control housing (4) by the respective locking ring (18).
The high voltage air heater according to claim 11, wherein each heater step (14) comprises a frame (48) encompassing the respective component and at the end portion of which the respective locking ring (18) is arranged.
The high voltage air heater according to claim 11 or 12, wherein the heater steps (14) are arranged approximately parallel and at a distance to each other in the interior of a main body housing (1).
A method for assembling a high voltage air heater according to any of the preceding claims, wherein assembly or fastening of the end portions of the components or of the frames (48) to the control housing (4) comprises the following steps in the order mentioned:
- moving of the end portion over the associated coupling projection (16), and

- rotating of the locking ring (18).