Abstract
An air heater for a vehicle, which comprises a subassembly for generating heat; a heat exchanger element thermally interacting with the subassembly; an external housing which receives the subassembly and the heat exchanger element, where the external housing and the heat exchanger form a heating air channel between them; a heating air blower, which is configured to draw in heating air via a heating air inlet of the external housing, convey this in a flow direction through the heating air channel and output it via a heating air outlet of the external housing; and a combustion air blower module comprising a combustion air blower which is powered by a motor and is configured, during operation, to draw in combustion air and supply the combustion air to the subassembly for generating heat.
Claims
1. An air heater for a vehicle, comprising: a subassembly for generating heat; a heat exchanger element thermally interacting with the subassembly; an external housing which receives the subassembly and the heat exchanger element, wherein the external housing and the heat exchanger element form a heating air channel between them; a heating air blower, which is configured to draw in heating air via a heating air inlet of the external housing, convey this in a flow direction through the heating air channel and output it via a heating air outlet of the external housing; a combustion air blower module comprising a combustion air blower which is powered by a motor and is configured, during operation, to draw in combustion air and supply the combustion air to the subassembly for generating heat, wherein the air heater establishes a longitudinal axis extending through the heating air inlet and the heating air outlet, characterized in that the combustion air blower module is configured to carry the external housing; the external housing comprises a first housing element and a second housing element as separate components; and the combustion air blower module, the first housing element and the second housing element are assembled together in an axial direction parallel to the longitudinal axis.
2. The air heater according to claim 1, wherein the first housing element and the second housing element are latched together in the axial direction parallel to the longitudinal axis by at least one latch connection.
3. The air heater according to claim 1, wherein the combustion air blower module comprises a combustion air blower housing component which is formed as one piece and at least partially forms the combustion air blower; and the combustion air blower housing component has a number of holding elements which extend substantially in the radial direction away from the longitudinal axis and support the external housing from the inside.
4. The air heater according to claim 3, wherein at least four of the holding elements are formed.
5. The air heater according to claim 3, wherein each of the holding elements comprises a web extending towards the outside from a housing portion of the combustion air blower housing component, and a supporting portion contacting the external housing.
6. The air heater according to claim 5, wherein the respective supporting portion contacting the external housing forms a free end of the corresponding holding element.
7. The air heater according to claim 5, wherein in the state in which the first housing element and the second housing element are latched together, the respective supporting portion contacting the external housing contacts and supports both the first housing element and the second housing element.
8. The air heater according to claim 5, wherein at least one of: the first housing element and the second housing element has a receiving portion which is formed on an inner wall of the housing element concerned, wherein the respective receiving portion extends in the axial direction starting from an edge face, at which at least one of: the first housing element and the second housing element lie opposite one another in assembled state, wherein the respective receiving portion is configured to receive the respective supporting portion, which contacts the external housing, slidingly in the axial direction, up to a stop face.
9. The air heater according to claim 7, wherein both the first housing element and the second housing element each have a receiving portion which, in assembled state, lie opposite one another in the axial direction and establish a common receiving region which, by form fit with the supporting portion, establishes an axial position of the holding element.
10. The air heater according to claim 5, wherein both the first housing element and the second housing element have a substantially square or rectangular cross-sectional profile in a respective plane perpendicular to the longitudinal axis; wherein a respective one of the supporting portions contacts and supports one of the four corners of the cross-sectional profile of at least one of: the first housing element and the second housing element.
11. The air heater according to claim 5, wherein the entirety of the holding elements has an overall X-shaped structure viewed in the direction along the longitudinal axis.
12. The air heater according to claim 1, wherein at least one of: the combustion air blower housing component is a diecasting; and both the first housing element and the second housing element are each integrally formed plastic mouldings.
13. A method for assembling an air heater comprising: provision of a subassembly, a heat exchanger element thermally interacting therewith, a combustion air blower module and a heating air blower; fitting of a first housing element and a second housing element in a respective opposite axial direction, parallel to a longitudinal axis; latching of the first housing element and the second housing element to at least one of: one another and the combustion air blower module.
14. An air heater for a vehicle, comprising: a subassembly for generating heat; a heat exchanger element thermally interacting with the subassembly; a combustion air blower module comprising a combustion air blower which is powered by a motor and is configured, during operation, to draw in combustion air and supply the combustion air to the subassembly for generating heat, wherein the air heater establishes a longitudinal axis extending parallel to a drive shaft of the motor; the motor for driving the combustion air blower; a control unit for controlling the motor; a holder for holding the control unit; characterized in that the control unit is provided with at least one latching element which interacts with a corresponding carrier element of the holder in a latch connection, in order to fasten the control unit to the holder.
15. The air heater according to claim 14, wherein the holder comprises two of the carrier elements, which extend parallel to the longitudinal axis, starting from the housing component; and the control unit is provided with at least two latching elements, each one of which interacts with one of the carrier elements.
16. The air heater according to claim 15, wherein the two carrier elements are configured as angled tabs.
17. The air heater according to claim 15, wherein the combustion air blower module comprises a combustion air blower housing component which is formed as one piece and at least partially forms the combustion air blower; and the corresponding carrier element extends parallel to the longitudinal axis, starting from the housing component.
18. The air heater according to claim 15, wherein the two carrier elements are formed as one piece with the combustion air blower housing component.
19. The air heater according to claim 15, wherein the latching elements in the respective latch connection extend perpendicularly to the respective carrier element concerned and parallel to one another, in order to allow the control unit, during its mounting, to be clipped onto the holder in a movement directed radially inwards towards the longitudinal axis.
20. The air heater according to claim 19, wherein the control unit has a control unit housing from which the latching elements extend and with which they are formed as one piece.
21. The air heater according to claim 20, wherein the control unit housing has a respective bearing protrusion, via which it bears on the carrier element, wherein when the control unit is in clipped-on state, the bearing protrusion and a latching lug fix the carrier element between them in the direction perpendicular to the longitudinal axis.
22. The air heater according to claim 20, wherein a first connection cage with exposed circuit board contacts therein is formed in the control unit housing of the control unit; and a second connection cage with exposed motor contacts therein is formed on a housing of the motor; wherein the second connection cage is configured to be received in the first connection cage in order to create an electrical connection between the circuit board contacts and the motor contacts.
23. The air heater according to claim 22, wherein when the motor is fixed to the combustion air blower housing component and the control unit is clipped onto the holder, the second connection cage is received in the first connection cage and the resulting form-fit connection fixes the control unit, in a circumferential direction about the longitudinal axis.
24. The air heater according to claim 22, wherein a circumferential seal is provided at least one of: on the inside on the first connection cage and on the outside on the second connection cage, so as to seal a space with the mutually contacting circuit board contacts and motor contacts inside the two connection cages.
25. The air heater according to claim 22, wherein the circuit board contacts are arranged directly on a control circuit board of the control unit and protrude into the first connection cage which is configured as a recess in the control unit housing.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] The invention is explained as an example below with reference to the appended figures.
[0062] In the drawings:
[0063] FIG. 1 shows, in a schematic overview, a longitudinal sectional view of a conventional fuel-powered air heater;
[0064] FIG. 2 shows a perspective view of a fuel-powered air heater according to a first exemplary embodiment, during fitting of the housing elements;
[0065] FIG. 3 shows, like FIG. 2 but in enlarged illustration, the latch connections of the housing elements;
[0066] FIG. 4 shows a perspective view of a combustion air blower module of the air heater from FIG. 2;
[0067] FIG. 5 shows a perspective view of the combustion air blower module from FIG. 4 without the outer (third) housing element;
[0068] FIG. 6 shows a lateral, longitudinal sectional view of the fuel-powered air heater according to the first exemplary embodiment;
[0069] FIG. 7 shows a perspective view of the external housing of the air heater from FIG. 2 in assembled or latched state;
[0070] FIGS. 8A,B show a perspective view of the combustion air blower module of the fuel-powered air heater according to the first exemplary embodiment, before (FIG. 8A) and after (FIG. 8B) fitting of a holder for an electronic control unit;
[0071] FIG. 9 shows a perspective view of a fuel-powered air heater according to a second exemplary embodiment;
[0072] FIGS. 10A,B show an axial plan view (FIG. 10A) and a perspective view (FIG. 10B) of a combustion air blower module of the fuel-powered air heater according to the second exemplary embodiment, with an integrated holder for an electronic control unit;
[0073] FIG. 11 shows a perspective view of the fuel-powered air heater according to the second exemplary embodiment, before fitting of the external housing consisting of two housing elements;
[0074] FIG. 12 shows, like FIG. 11 but in perspective view, a section perpendicular to a longitudinal axis through the structure of internal components of the air heater from FIG. 9 (with external housing removed), in a viewing direction from the housing of the combustion air blower (in front) to the heating air blower (behind);
[0075] FIG. 13 is like FIG. 11, but with first housing element fitted;
[0076] FIG. 14 is like FIG. 12, but with first housing element fitted;
[0077] FIGS. 15A,B show an enlarged perspective view of extracts of a receiving portion of the second housing element (FIG. 10A) and the receiving holding element on the combustion air blower module;
[0078] FIG. 16 shows a section through the second housing element in perspective view;
[0079] FIG. 17 shows a section through the first housing element in perspective view;
[0080] FIG. 18 is like FIG. 12 or 14, but now also with fitted second housing element, wherein the section through the air heater according to the second exemplary embodiment lies at the height of the combustion chamber;
[0081] FIG. 19 shows a perspective view of the combustion air blower module with motor fitted thereon and with mounted control unit according to the second exemplary embodiment, viewed from obliquely below;
[0082] FIG. 20 is like FIG. 19, but from a different perspective (from obliquely above);
[0083] FIG. 21 shows a perspective view of the electronic control unit or its control unit housing according to the second exemplary embodiment;
[0084] FIG. 22 shows a plan view of the combustion air blower module with motor fitted thereon, during the clip-fitting or mounting of the control unit;
[0085] FIG. 23 is like FIG. 22, but with mounted control unit;
[0086] FIG. 24 shows an enlarged illustration of the latching element of the control unit in the state latched to the holder of the combustion air blower module;
[0087] FIGS. 25A,B show a cross-section (FIG. 25A) and a side view (FIG. 25B) of the electric motor of the air heater according to the second exemplary embodiment, with a second connection cage on the motor side;
[0088] FIG. 26 shows a perspective view of the control circuit board with circuit board contacts fitted thereon, for a first connection cage on the control unit side;
[0089] FIG. 27 shows a perspective view from below of the control unit with the first connection cage arranged (recessed) in the control unit housing;
[0090] FIGS. 28A,B show a sectional view of a state of the motor and control unit before fitting (clip-fitting-FIG. 28A) and after fitting of the control unit;
[0091] FIG. 29 shows a perspective view of the circumferential seal, shown in FIGS. 28A and B, for the connection cages;
[0092] FIGS. 30A,B show an axial plan view (FIG. 30A) and a perspective view (FIG. 30B) of the control unit and motor parts coupled together.
DETAILED DESCRIPTION:
[0093] In the following description of the drawings, the same reference signs designate the same or comparable components. The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for the implementation of the invention, both individually and also in arbitrary combination.
[0094] FIG. 1 shows a schematic, longitudinal sectional view, giving an overview of a conventional fuel-powered air heater 2, by means of which the fundamental structure also applicable to the exemplary embodiments will be explained. The air heater 2 is intended e.g. for use in a motor vehicle. The air heater 2 has an external housing G with an intake opening or heating air inlet 14 for heating air H, and with an output opening or heating air outlet 22 for the warmed heating air H. A combustion chamber housing with a fuel-powered combustion chamber 11 is situated in a heat exchanger element 13 of the air heater 2. A combustion air blower, which is arranged in a combustion air blower module 6 and configured as a side channel compressor (not shown in detail), ensures the supply and throughflow of combustion air in the combustion chamber 11. The combustion air blower is connected to a laterally arranged combustion air inlet 9, via which it draws in the combustion air. The figure does not show in detail a fuel supply line (which is however given reference sign 38 below), a vaporizer for the fuel, and an ignition apparatus for starting a combustion process. The fuel and the combustion air containing the oxidizer (e.g. oxygen) are brought into a chemical reaction in the combustion chamber 11, in order to generate heat.
[0095] The heating air H is drawn in from the environment via the heating air inlet 14 by means of a heating air blower 3 on an end face of the air heater 2, and after flowing around the heat exchanger 13 in corresponding heating air channels, emerges in heated state through the heating air outlet 22 on a back side of the air heater 2 opposite the end face.
[0096] A generally multipiece external housing G surrounds the functional components of the air heater 2. In the region of the heat exchanger element 13, the heating air channels are formed between the heat exchanger element 13 and an inner wall of the external housing G. In a front region of the external housing G, the heating air Hwhich is not yet heatedflows around such components as the control unit ECU, the motor M and the combustion air blower module 6, after flowing through an impeller of the heating air blower 3. Purely as an example, the heating air inlet 14 and the heating air outlet 22 of the air heater 2 form a common spatial longitudinal axis L of the air heater 2. As a whole, the heating air H driven by the heating air blower 3 flows accordingly in a direction RH parallel to the longitudinal axis L. The combustion air blower of the combustion air blower module 6, and the heating air blower 3 are jointly driven by a drive motor M, which is controlled by a control device ECU in the known fashion, in particular depending on a required heating power.
[0097] On an exhaust gas side of the heat exchanger 13, after combustion in the combustion chamber 11, hot combustion gases flow as a rebound flow against a wall in a region of the heat exchanger which is at the rear in a longitudinal direction. In FIG. 1, the combustion chamber 11 is shown purely schematically, and a flame tube tapering in the flow direction may adjoin this in the usual fashion. After leaving the combustion chamber or flame tube, and after the rebound flow against the wall of the heat exchanger, the combustion gases are deflected sharply through 180 and then flow in the flow direction opposite the heating air flow, on the outside of the heat exchanger 13, to the exhaust gas outlet 15. A heat exchanger structured in this fashion may also be described as a contraflow heat exchanger.
[0098] The exhaust gases are here diverted through flow channels which, for better heat transmission, are formed by ribs (not shown) protruding towards the inside from an inner surface of the heat exchanger 13 and extending along the longitudinal axis L. With this structure, during operation, the heat exchanger element 13 reaches a maximum temperature in the rear region, the temperature decreasing from back to front as the heat transmission progresses. Accordingly, the heating air in the heating air channels reaches the highest temperatures close to a rear region, before being output from the heating air outlet 22. This configuration, as described to this extent, is also applicable to the exemplary embodiments described below.
[0099] FIGS. 2 to 8B show a first exemplary embodiment of a fuel-based air heater 2. Some differences from the example in FIG. 1 are explained below, while with respect to corresponding features, reference is made to the above description.
[0100] The air heater 2 has an external housing G formed from two housing shells, as shown in FIG. 2. The two housing shells are here called first housing element 10 and second housing element 18. The first housing element 10 simultaneously forms an air inlet hood 12 which comprises the heating air inlet 14, and the second housing element 18 simultaneously forms an air outlet hood 20 which comprises the heating air outlet 22.
[0101] FIG. 2 shows the state of mounting of the housing shells, while FIG. 7 shows the assembled state of the external housing G. For the purpose of mounting, the two housing elements 10 and 18 are brought together in mounting directions C1 and C2, parallel to and along the longitudinal axis L, and latched together. For the latching, the combustion air blower module 6 (shown in greater detail in FIG. 4) is available. In fitted state, this is enclosed by the two housing elements 10 and 18 in the manner of a sandwich.
[0102] The combustion air blower module 6 comprises the actual combustion air blower which, as shown in FIG. 4, is formed by a combustion air blower housing part 7. The combustion air inlet 9 extends into the combustion air blower. A frame 5, configured as a thin rib, extends all around on the outside and already anticipates the substantially square cross-sectional profile of the external housing G. The frame 5 and the combustion air inlet 9 are formed as an aluminium diecasting, integrally with the combustion air blower housing part 7. The frame 5 is connected to the combustion air blower housing part 7 via struts 55, shown in FIG. 5. Flow openings 53 (see also FIG. 5) for the heating air H are formed between the frame 5, the struts 55 and the combustion air blower housing part 7, so that the heating air can pass from a front part of the air heater 2 into a rear part with the heat exchanger element 13. On the outside, the frame 5 supports over a large area a slender third housing element 4, which may be made from a plastic injection-moulding in the same way as the housing elements 10, 18. Two openings, as first latching elements 26 (to be explained below), are formed in each case on opposite sides in the third housing element 4.
[0103] FIG. 3 shows in greater detail a respective latch connection 24 between the third housing element 4 and the first housing element 10 on one side, and the second housing element 18 on the other. On mounting, a front side 16 of the third housing element 4 lies opposite the first housing element 10, and a rear side 8 of the third housing element 4 lies opposite the second housing element 18. The two housing elements 10, 18 each have elastic tabs 27, on which respective protrusions are formed as second latching elements 28. By means of the elastic tabs 27, these elements can engage in the corresponding openings of the first latching elements on the side of the third housing element 4, when the first and second housing elements are pushed together in the axial directions C1, C2 onto the third housing element 4 of the combustion air blower module 6. In assembled state, the combustion air blower module 6 completely supports or carries the external housing G constructed from two shells.
[0104] Because of this housing structure of the air heater 2 according to the first exemplary embodiment, during production, a continuous axial orientation of the workpiece carrier is possible, without in particular requiring rotations through e.g. 90.
[0105] FIG. 6 shows a longitudinal section through the air heater 2 according to the first exemplary embodiment. Reference sign 32 indicates an electrical line which supplies power to the air heater. Corresponding cable passages in the external housing are not shown in FIGS. 2, 4 and 7 for the sake of clarity, but in principle are present.
[0106] FIG. 5 illustrates an alternative embodiment of the combustion air blower housing component. This shows openings 52 milled at the corresponding positions in the frame 5 for the cable outlets. Furthermore, fastening holes 51 for fitting of the first and second housing elements to the frame 5 can also be seen.
[0107] These milling processes constitute additional process steps, and in total four latch connections 24 are required (two latch connections on each of the two opposite sides of the air heater 2) in order to achieve a stable external housing configuration. Furthermore, as shown in FIGS. 8A and 8B, an additional holder is required for the control unit ECU which is to control the motor M, requiring additional mounting parts (screws, separate holder) and yet a further joining step. In addition, as described initially, the diecasting process for the combustion air blower housing component 7 imposes high requirements, if also the frame is to be formed integrally with this component. The anchoring point for the casting mould lies in the region of the shaft bearing, which is indicated by the bore 71 for the shaft 31 of the electric motor M in FIG. 5.
[0108] Starting from the concept of the first exemplary embodiment shown in FIGS. 2 to 8B, therefore a second exemplary embodiment has been designed which also provides solutions to the points mentioned and further improvements.
[0109] FIG. 9 shows a perspective view of a fuel-powered air heater 102 according to the second exemplary embodiment. It should be noted that the flow direction RH of the heating air H in FIGS. 9 to 30B, concerning the second exemplary embodiment, is from right to left. In the same way as the first exemplary embodiment, here too there is a two-piece housing structure of the external housing G, with a first housing element 110 and a second housing element 118, which here again correspond to a heating air inlet hood 112 with heating air inlet 14 and an air outlet hood 120 with heating air outlet 22. The fundamental functional inner structure of the air heater 102 is the same as described with reference to FIG. 1. FIG. 9 shows the combustion air inlet 9, the exhaust gas outlet 15 and the fuel supply line 38.
[0110] A cable passage (without reference sign) can be seen slightly above the combustion air inlet 9. Even further above in FIG. 9 is a latch connection 124, which is now formed directly between the first housing element 110 and the second housing element 118. This comprises, on the side of the second housing element 118, an opening formed in its wall as the first latching element 126, and on the side of the first housing element 110, a protrusion formed on an outer surface of the first housing element 110 as the second latching element 128. As in the first exemplary embodiment, in the case of latching, the latching elements 126, 128 form a form-fit connection. As shown in FIG. 17, which illustrates a longitudinal section through the first housing element 110, the protruding second latching element 128 is formed on an elastic tab 127, so that the process of latching to the first latching element 126 can be carried out more easily. The two latching elements 126, 128 are formed elongate, so that latching is possible only if the two housing elements are brought together in the axial direction along the longitudinal axis L (which here again is established e.g. by an axis running through a heating air inlet and heating air outlet or, as an equivalent, by an axis running along the shaft of the blower motor M).
[0111] This structure already achieves at least the same advantages as the first exemplary embodiment, in particularinter aliaan axial mounting direction of all housing shells concerned and a reduction in the number thereof. In addition, however, also the corresponding combustion air blower module 106 of the second exemplary embodiment can be simplified, since the third housing element 4 as a docking element is omitted. This also reduces the number of latch connections from four to two (one latch connection on each of the two opposite sides of the air heater). Furthermore, as a comparison of FIG. 7 and FIG. 9 shows, the number of joining gaps F is also reduced from two to one. Accordingly, the heating air leakage from the interior of the air heater 102 is also reduced.
[0112] The combustion air blower module 106 according to the second exemplary embodiment is shown in FIGS. 10A and 10B. Here, in comparison with the first exemplary embodiment, not only is the third housing element 4 omitted as part of the combustion air blower module 106, but also the frame 5. Instead, in the second exemplary embodiment, holding elements 105 are provided which extend radially outwards from a portion of the combustion air blower housing component 107. As most clearly evident in FIG. 14, these holding elements 105 support or carry the external housing G orin the state of FIG. 14the first housing element 110. The holding elements 105 comprise a web portion 152 and a contact portion 151, which is configured as a foot, in order to bear against an inner wall 202 or 122 (see FIGS. 16 and 17) of the first housing element 110 and the second housing element 118.
[0113] The combustion air blower module 106 furthermore comprises a holder 140 which is formed integrally with the combustion air blower housing component 107 and will be explained further below, and bores 171 for fastening the combustion air blower housing component 107 to further components, such as the heat exchanger element 13, in the axial direction. Reference sign 71 here again designates the bore for the bearing of the shaft of the blower motor M. Threaded bores 172 serve for fitting the blower motor M, also in the axial direction. It should be noted that, for stability reasons, the holding elements 105 comprise web portions which also already extend in the radial direction past the combustion air blower housing component 107 into its middle region, so that because the holding elements 105 extend into the four corners of the generally square cross-sectional profile of the external housing G, the design is X-shaped in axial plan view (along the longitudinal axis L), as can be seen particularly clearly in FIG. 10A.
[0114] FIG. 11 shows the air heater 102 with external housing G not yet mounted. The components already described with reference to FIG. 1 can be seen. Reference sign 131 designates a sealing plate (part of the heat exchanger element) which covers a region on the underside of the air heater 102. It is formed integrally with the heat exchanger element 13 and therefore is not a plastic injection-moulding, but is made from metal, and in particular is connected to the exhaust gas outlet 15. It closes a region not covered by the housing elements 110 and 118, and thereby seals the interior of the external housing G towards the outside. Sign 173 designates a fastening means for the bore 172 (see FIG. 10A).
[0115] FIG. 12 shows the same state as FIG. 11 from a different perspective, but with a section through the air heater, so that the combustion air blower housing component 107 and in particular the side channel impeller housing can be seen. Here too, the shaft 31 for the blower motor can be seen. The impeller for the heating air blower 3 is in the background.
[0116] FIGS. 13 and 14 show the state during the mounting process after fitting of the first housing element 110, correspondingly in the perspective side view and the sectional view. The holding elements 105 sit in the four corners of the cross-sectional profile of the first housing element 110, but protrude in the axial direction along the longitudinal axis L from the opening of the fitted first housing element 110.
[0117] FIG. 15A shows as an example one of the corners of the second housing element 118 in enlarged illustration. The corresponding corner of the first housing element 110 shown in FIG. 14 has substantially corresponding features. A particular feature of the second housing element 118 in this respect is simply a collar portion 181 which, on mounting on the first housing element 110, extends slightly over its outer surface.
[0118] In the corners or edges of the two housing elements, ribs 190, 209 (see FIGS. 15 and 16) are formed, of which a middle one is formed shortened towards the outer edge in order to clear a receiving portion 188 for the contact portion 151 of the holding element 105, and to form a stop face 186 which defines the position of the contact portion 151 in the interior of the second housing element 118. The same applies accordingly to the first housing element 110. For this reason, the first housing element 110 also cannot be pushed on further in FIG. 14, so that the holding element 105 semi-protrudes.
[0119] FIG. 15B shows a holding element 105 in enlarged illustration. The foot-like contact portion 151 has two opposite stop faces 159, of which in mounted state one hits against the stop face 186 shown in FIG. 15A, and the other hits against the corresponding stop face (not shown) in the first housing element 110. Furthermore, the foot-like contact portion 151 has two lateral contact faces 156, 157 with which it contacts receiving faces 184, 185 of the outer ribs 190 (209 similarly). In this way, a form-fit connection is achieved between the contact portion 151 and a receiving portion 208, similar to the receiving portion 188 from FIG. 15A, on the side of the first housing element 110 (see FIG. 17).
[0120] The second housing element 118 is then fitted, as FIG. 18 shows (the section through the air heater is here pulled further in the backward direction, and at the front the second housing element 118 is visible all around). Here, now, the part of the contact portion 151 still protruding from the first housing element 110, of the holding element 105 enters the corresponding receiving portion 188 of the second housing element 118. In this state, the receiving portions 188, 208 are contacted by the contact face 158 of the foot-like contact portion 151. Because of the X-shaped configuration of the four holding elements 105, during mounting, the foot-like contact portions 151 each slide with precise fit into the receiving portions 188, 208 of the corresponding opening of the housing element 110, 118 concerned, until the associated stop faces 186, 159 of the foot-like contact portion 151 and the two housing elements 110, 118 meet one another. In the state in which the latch connections 124 are created, the four stop faces 186, 159 etc. contact one another, so that the axial position of the housing elements 110, 118 relative to the combustion air blower module 106 is fixed. Because of the form fit of the X-shaped structure, a rotation of the external housing about the longitudinal axis L is also excluded. It should be noted that two latch connections 124 alone are sufficient for this, and no further screw connections are required.
[0121] FIGS. 19 and 20 show perspective views of the combustion air blower module with motor M fitted thereon and with mounted control unit ECU according to the second exemplary embodiment, with viewing direction from obliquely below and from obliquely above. The electric motor M is fitted directly on the combustion air blower module 106 by means of screws (see the bores 172 in FIG. 10A). The control unit ECU is fitted on the holder 140, here by clip-fitting from the lateral direction, by means of four latch connections 300 (see FIG. 24).
[0122] The holder 140 comprises two angled tabs, which extend linearly along the longitudinal axis L from the combustion air blower housing part 107 and parallel to one another, and which have a vertical portion (first angle face 142) and a horizontal portion (second angle face 144). The portions 142, 144 stand for example perpendicularly to one another, see FIG. 24. The angled tabs may be produced integrally with the aluminium diecasting of the combustion air blower housing part 107, which further reduces the total number of components.
[0123] FIG. 21 shows the control unit ECU in greater detail. It comprises a control unit housing 210 which has a lid 212 and a housing lower part 214. The structure of the control unit housing 210 is generally flat, in order to receive therein a control circuit board 260, shown in FIG. 26. The control circuit board 260 establishes a plane in the control unit housing 210, wherein a direction A of clip-fitting of the control unit housing 210 lies perpendicular to this plane. Some connection sockets 218, oriented in the clip-fitting direction A, are formed on the housing lower part 214 and allow an electrical connection of the control unit ECU to the on-board network (communication and power supply) of the vehicle, see also the above-discussed cable passage K in FIGS. 13, 16 and 17, and electrical line 32 in FIG. 6 concerning the first exemplary embodiment.
[0124] In particular, however, four latching elements 220also extending in the clip-fitting direction Aare provided, which extend parallel to one another from the housing lower part 214. As shown in the enlarged illustration in FIG. 24, these each comprise a flexible latching arm 222 and a latching lug 224. In each case, one latching element and one of the two angled tabs of the holder 140 form a latch connection 300. In each case, two latching lugs 224 of the latching elements face one another, so that during clipping onto the holder 140, the latching elements 222 grip around the outside of the angled tabs; in engaged state, the latching arms 222 conform closely to the outside of the vertical portions (angle faces 142), and the latching lugs grip under a distal end of the vertical portions (angle faces 142), so that the control unit housing 210 can no longer be released against the clip-fitting direction A. Furthermore, on the underside of the housing lower part 214, bearing protrusions 215 are formed which, in a state in which the latching lugs 224 engage below the angled tabs of the holder 140, contact said latching tabs from above and thereby limit a further movement in the clip-fitting direction A. Thus the control unit ECU is fixed by form fit in the clip-fitting direction A, which lies perpendicular to the extent direction of the angled tabs and to the longitudinal axis L. The process of clip-fitting is shown in FIGS. 22 and 23.
[0125] FIG. 27 shows the underside of the housing lower part 214 of the control unit housing 210 in greater detail. As well as the laterally arranged, raised connection sockets 218 for connection via plugs to cables or electrical lines, in the middle position, a first connection cage 260 is formed as a recess in the surface of the housing lower part 214. From the interior of the control unit housing 210, three circuit board contacts 262, formed as fork-like contacts, protrude into this first connection cage 260. The fork-like shape creates a flexible and reliable connection to the e.g. pin-like or plate-like motor contacts 250. The circuit board contacts 262, as shown in FIG. 26, are arranged directly on the circuit board and connected to electronic components provided there, which allow control or operation of the motor M. Adjacent to the first connection cage 264, a cylindrical recess 217 is formed in the surface of the housing lower part 214, the shape of which recess is complementary to the cylindrical housing of the electric motor M (see FIG. 19 for example).
[0126] FIGS. 25A and 25B show, in cross-sectional view (FIG. 25A) and in side view (FIG. 25B), the electric motor M of the air heater according to the second exemplary embodiment. The motor M has three motor contacts 250 for connection of the e.g. three phases of the motor M. The motor contacts 250 are arranged inside a second connection cage 240 on the motor side, which is injection-moulded together with a motor bearing plate 244 and has a shape and external dimensions which allow it to fit precisely into the recess of the first connection cage 264.
[0127] FIGS. 28A and 28B show the contacting of the electric motor M to the control unit ECU. A sealing ring 242 (shown in FIG. 29) is formed on an outer edge of the second connection cage 240, in order to seal an inner space formed by the two connection cages 240, 264 when they are pushed together. FIGS. 30A and 30B show the mounted state of the motor M and control unit ECU from different perspectives. Here, the combustion air blower module 106 is not shown.
[0128] FIGS. 22 and 23 show the clip-fitting process, including the combustion air blower module 106 with the holder 140. The enlargement in FIG. 24 should be consulted here. The clip-fitting to create the latch connection 300 is here accompanied by the insertion of the second connection cage 240 on the motor side in the first connection cage 264 on the control unit side. The latter connection fixes the control unit by form fit, in particular in a direction perpendicular to the clip-fitting direction A, e.g. along the longitudinal axis L, so that e.g. a sliding of the control unit along the angled tabs is eliminated. In total, this gives the control unit a mechanically stable and reliable positioning without the use of screw connections.
[0129] It should be noted that although the embodiments of FIGS. 9 to 18 firstly, and FIGS. 19 to 30B secondly, concern the same exemplary embodiment, they concern mutually independent improvements and may each be implemented without the other improvement, for which reason they are also considered above as different aspects of the invention. However, synergy effects from the combination can evidently not be excluded.
LIST OF REFERENCE SIGNS
[0130] 2 Air heater [0131] 3 Heating air blower [0132] 4 Third housing element [0133] 5 Holding element for the external housing (frame structure) [0134] 6 Combustion air blower module [0135] 7 Combustion air blower housing part [0136] 8 Back side (third housing element) [0137] 9 Combustion air inlet [0138] 10 First housing element [0139] 11 Combustion chamber [0140] 12 Air inlet hood [0141] 13 Heat exchanger element [0142] 14 Heating air inlet [0143] 15 Exhaust gas outlet [0144] 16 Front side (third housing element) [0145] 18 Second housing element [0146] 20 Air outlet hood [0147] 22 Heating air outlet [0148] 24 Latch connection [0149] 26 First latching element [0150] 27 Elastic tab [0151] 28 Second latching element [0152] 31 Shaft (blower motor) [0153] 32 Electrical line [0154] 34 Supporting structure [0155] 36 Heater module [0156] 38 Fuel supply line [0157] 51 Fastening holes [0158] 52 Openings for cable outlets [0159] 53 Flow opening (for heating air) [0160] 55 Radial struts [0161] 56 Holder for control unit [0162] 57 Screws for fastening the holder [0163] 71 Bore in combustion air blower module for shaft [0164] 102 Air heater [0165] 105 Holding element for the external housing [0166] 106 Combustion air blower module [0167] 107 Combustion air blower housing part [0168] 110 First housing element [0169] 112 Air inlet hood [0170] 118 Second housing element [0171] 120 Air outlet hood [0172] 122 Inner wall (air outlet hood) [0173] 124 Latch connection [0174] 126 First latching element [0175] 127 Elastic tabs [0176] 128 Second latching element [0177] 131 Sealing plate (part of heat exchanger element) [0178] 140 Holder for control unit (support tabs) [0179] 141a, b Angled tab [0180] 142 First angle face [0181] 144 Second angle face [0182] 151 Supporting portion [0183] 152 Radial web [0184] 156 Contact face [0185] 157 Contact face [0186] 158 Contact face [0187] 159 Stop face (in axial direction) [0188] 171 Bores for fastening the heat exchanger element [0189] 172 Bores for fastening the motor [0190] 173 Fastening means for bores 171 [0191] 181 Collar portion [0192] 184 Receiving face (in circumferential direction) [0193] 185 Receiving face (in circumferential direction) [0194] 186 Stop face (air outlet hood, in axial direction) [0195] 188 Receiving portion (air outlet hood) [0196] 190 Ribs (air outlet hood) [0197] 202 Inner wall (air inlet hood) [0198] 206 Stop face (air inlet hood, in axial direction) [0199] 208 Receiving portion (air inlet hood) [0200] 209 Ribs (air inlet hood) [0201] 210 Control unit housing [0202] 212 Lid [0203] 214 Housing lower part [0204] 215 Bearing protrusion [0205] 216 Lid fastening [0206] 217 Receiver in housing lower part for cylindrical motor housing [0207] 218 Connection sockets (control unit) [0208] 220 Latching elements (control unit) [0209] 222 Latching arm [0210] 224 Latching lug [0211] 240 Connection cage (motor) [0212] 242 Seal on motor-side connection cage [0213] 244 Motor bearing plate [0214] 250 Motor contacts [0215] 260 Control circuit board [0216] 262 Fork-like circuit board contacts [0217] 264 Connection cage (control unit) [0218] 300 Latch connection [0219] A Lateral fitting direction (radial direction) [0220] C1, C2 Mounting directions for the housing elements [0221] ECU Control unit [0222] F Joining point [0223] G External housing [0224] H Heating air [0225] K Cable passage [0226] L Longitudinal axis [0227] M Motor [0228] R.sub.H General direction of heating air flow
