Heating unit and method for manufacturing thereof

Abstract

 The invention relates to a hating unit comprising a plate heat exchanger (10) having a plurality of heat exchanger plates combined to form a plate stack defining flow passages of a primary circuit (15) having a heat-emitting liquid inlet (11) and a heat-emitting liquid outlet (13) and flow passages of a secondary circuit (16) having a heat-absorbing liquid inlet (14) and a heat-absorbing liquid outlet (12), a heat-emitting liquid supply channel (61) for guiding heat-emitting liquid from a heat-emitting liquid supply line to the heat-emitting liquid inlet (11), a heat-emitting liquid discharge channel (63) for guiding heat-emitting liquid from the heat-emitting liquid outlet (13) to a heat-emitting liquid discharge line, a heat-absorbing liquid supply channel (64) for guiding heat-absorbing liquid from a heat-absorbing liquid supply line for supplying heat-absorbing liquid to the heat-absorbing liquid inlet (14), and a heat-absorbing liquid discharge channel (62) for guiding heat-absorbing liquid from the heat-absorbing liquid outlet (12) to a heat-absorbing liquid discharge line, wherein the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62) are adapted and arranged to enable heat transmission from heat-emitting liquid in the heat-emitting liquid supply channel (61) to heat-absorbing liquid in the heat-absorbing liquid discharge channel (62), wherein the heating unit comprises a middle plate (20) and an end plate (40) having openings (31, 32, 33, 34) and/or pressed indents defining the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62).

Description

[0001] The present invention relates to a heating unit in accordance with the preamble of claim 1 and a method for manufacturing thereof.

[0002] A heating unit in accordance with the preamble of claim 1 is known from EP 1 500 896 A1, wherein the whole contents thereof is incorporated into the present specification by reference.

[0003] The heating unit of EP 1 500 896 A1 comprises a gasketed plate heat exchanger with a coupling element containing channels from the liquid supply and discharge lines to the heat exchanger. The coupling element comprises a casted block. The heating unit of EP 1 500 896 A1 is relatively heavy.

[0004] Accordingly it is an object of the present invention to provide a heating unit which is light-weighted and easy to manufacture.

[0005] The object of the invention is achieved by a heating unit in accordance with the features of claim 1. Preferred embodiments of the invention are disclosed in the dependent claims.

[0006] In accordance with the invention there is provided a heating unit comprising a plate heat exchanger having a plurality of heat exchanger plates combined to form a plate stack defining flow passages of a primary circuit having a heat-emitting liquid inlet and a heat-emitting liquid outlet and flow passages of a secondary circuit having a heat-absorbing liquid inlet and a heat-absorbing liquid outlet, a heat-emitting liquid supply channel for guiding heat-emitting liquid from a heat-emitting liquid supply line to the heat-emitting liquid inlet, a heat-emitting liquid discharge channel for guiding heat-emitting liquid from the heat-emitting liquid outlet to a heat-emitting liquid discharge line, a heat-absorbing liquid supply channel for guiding heat-absorbing liquid from a heat-absorbing liquid supply line for supplying heat-absorbing liquid to the heat-absorbing liquid inlet, and a heat-absorbing liquid discharge channel for guiding heat-absorbing liquid from the heat-absorbing liquid outlet to a heat-absorbing liquid discharge line, wherein the heat-emitting liquid supply channel and the heat-absorbing liquid discharge channel are adapted and arranged to enable heat transmission from heat-emitting liquid in the heat-emitting liquid supply channel to heat-absorbing liquid in the heat-absorbing liquid discharge channel, wherein the heating unit comprises a middle plate and an end plate having openings and/or pressed indents defining the heat-emitting liquid supply channel and the heat-absorbing liquid discharge channel.

[0007] In accordance with the invention the middle plate and the end plate can be steel plates, preferably stainless steel plates. In accordance with the invention the middle plate and the end plate can have a thickness of about 0.5 mm to 5 mm, preferably a thickness of about of 1 mm to 3 mm 1 and can preferably have a thickness of about 2 mm.

[0008] In accordance with the invention the middle plate can have openings and the end plate can have pressed indents defining the heat-emitting liquid supply channel and the heat-absorbing liquid discharge channel.

[0009] In accordance with the invention the middle plate and the end plate can have openings and/or pressed indents defining the heat-emitting liquid discharge channel and the heat-absorbing liquid supply channel.

[0010] In accordance with the invention the heating unit can comprise connection members for connecting the channels to connectors for connecting the channels to the respective supply and discharge lines, wherein preferably the middle plate can comprise pressed indents defining receiving portions for the connection members and/or the end plate can comprise pressed indents defining receiving portions for the connection members.

[0011] In accordance with the invention heating unit can comprise at least one or a plurality of clinch joints defining the relative position of the middle plate with respect to the end plate.

[0012] In accordance with the invention heating unit can comprise at least one snap fit or a plurality of snap fits defining the relative position of the middle plate 20) with respect to the end plate, wherein the or each snap fit preferably comprises a snap fit indent provided in middle plate and a snap fit indent (400) provided in the end plate.

[0013] In accordance with the invention the clinched joints and/or snap fits can be preferably be evenly spaced from each other. In accordance with the invention the clinched joints and/or snap fits can be provided at the edges of the middle plate and the end plate. Preferably the clinched joints and/or snap fits can be provided in the extension portions of the middle plate and the end plate.

[0014] In accordance with the invention the or each snap fit can comprise a snap fit indent provided in middle plate and a snap fit indent provided in the end plate.

[0015] In accordance with the invention, the snap fit indent(s) provided in middle plate and the snap fit indent(s) provided in the end plate can have similar shapes fitting together. For instance the shapes can be oval, rectangular, circular or irregular shaped. Other shapes are possible. Preferably the shapes of different snap fits are the same. However the shapes of different snap fits can also be different from each other. Even the shapes of the indents in the middle plate and end plate of one snap fit can be different as long as a snap fit connection is provided such that an alignment of the middle plate and the end plate in at least one direction is ensured during the joining step. Preferably the snap fit indent(s) provided in middle plate and the snap fit indent(s) provided in the end plate can comprise respective protrusions and recesses being adapted and dimensioned such that the middle plate and the end plate can be snapped together before they are joined together in a further step, preferably a brazing step, wherein a copper foil is placed between the parts to be brazed together. In accordance with the invention the copper foil can be provided with recesses in the area where the snap fit connection is provided. Alternatively copper foil can be provided also in the area of the snap fit connection.

[0016] In accordance with the invention the middle plate and the end plate can be brazed together.

[0017] In accordance with the invention the plate heat exchanger can be a brazed plate heat exchanger or a gasketed plate heat exchanger.

[0018] Alternatively or in addition the middle plate and the end plate can be at least partially be glued or welded together. Other connection methods are possible. Preferably the connection members can be brazed to the middle plate and the end plate and the plates of the plate heat exchanger can be also brazed together. In addition the middle plate can be preferably brazed to the uppermost plate of the plate heat exchanger being adjacent thereto.

[0019] In accordance with the invention portions of the heat-emitting liquid supply channel and the heat-absorbing liquid discharge channel can be arranged next to each other.

[0020] This enables a heat transfer form liquid in one channel to liquid in the other channel without having the need of flowing through the plate heat exchanger, especially when there is a low or no demand for heat. The heat transmission from the heat-emitting liquid in the heat-emitting liquid supply channel to the heat-absorbing liquid discharge channel ensures that the temperature of the heat-absorbing liquid does not fall so quickly under a pre-determined threshold value, such that the consumption of energy can be reduced, as explained in further detail in EP 1 500 896 A2.

[0021] In accordance with the invention the heat-emitting liquid supply channel and the heat-absorbing liquid discharge channel can extend from the top portion of the middle plate and the end plate to the bottom portion of the middle plate and the end plate.

[0022] In accordance with the invention the heat-emitting liquid supply channel and the heat-absorbing liquid discharge channel can be curved.

[0023] This embodiment of the invention has the advantage that the length of the heat-emitting liquid supply channel and the heat-absorbing liquid discharge channel can be greater than for embodiments of the invention where the channels extend directly from the respective inlet/outlet of the plate heat exchanger to the respective connection member. Accordingly a better heat transfer between the liquids in the channels can take place. Preferably the length of these channels can be greater that the length of the middle and end plate.

[0024] In accordance with the invention there is also provided a method for manufacturing a heating unit according to any of the preceding claims, wherein the plates of the plate heat exchanger and the middle plate and the end plate are brazed together.

[0025] In accordance with the invention the middle plate and the end plate can comprise respective receiving portions for connection members and the middle plate, the connection members and the end plate can be brazed together.

[0026] In accordance with the invention all parts to be brazed together can be brazed together in one brazing step.

[0027] In accordance with the invention the end plate and the middle plate can be clinched together by means of at least one and preferably more than one clinched joints before the brazing step takes place in order to ensure the correct alignment of the end plate to the middle plate.

[0028] Alternatively or preferably in addition the middle plate may be clinched to the neighbouring heat exchanger plate (i.e. the last heat exchanger plate closing the heat exchanger at this side) by means of at least one and preferably more than one clinched joints before the brazing step takes place in order to ensure the correct alignment of the middle plate to the heat exchanger plate.

[0029] Alternatively or preferably in addition the heat exchanger plates or at least some of the heat exchanger plates may be clinched together by means of at least one and preferably more than one clinched joints before the brazing step takes place in order to ensure the correct alignment of the stack of heat exchanger plates.

[0030] Preferably the brazing step takes place at 1200 °C, wherein all parts are placed into an oven and pressed together, wherein the plates of the heat exchanger preferably comprising indents in the corners of the heat exchanger plates such that the correct alignment during the brazing step is ensured.

[0031] Alternatively or in addition to the snap fits the middle plate and/or the end plate can comprise indents corresponding to at least on corner indent of the heat exchanger plates and preferably with the corner indents of the heat exchanger plates such that an correct alignment of the middle plate to the stack of heat exchanger plates and/or an correct alignment of the end plate to the middle plate is ensured during the brazing step.

[0032] In accordance with the invention respective copper foils can be placed between all parts to be brazed together before the brazing step.

[0033] In accordance with the invention, for embodiments having a brazed plate heat exchanger, the plates of the heat exchanger can be fixed for brazing by means of bending on edge portions of the heat exchanger plates and/or by providing clinched joints. For instance clinched joints and/or bendings may be provided at the top at three protrusions of the heat exchanger plates.

[0034] Alternatively there may be provided at least one or more, especially two bendings of corners and/or clinched joints in the top of the heat exchanger plates. This may be sufficient to ensure a correct alignment of the heat exchanger plates in the horizontal direction. In the vertical direction the correct alignment of the heat exchanger plates may be ensured by putting a weight on top of the heat exchanger plates.

[0035] The invention will be explained in further detail with reference to the drawings, wherein the following reference numbers are used:

1

clinch joint

2

connection pipe

3

regulator

4

temperature sensor

5

safety valve

6

closing valve

7

non-return valve

8

signal line

10

brazed plate heat exchanger

11

heat-emitting liquid inlet (of primary circuit)

12

heat-absorbing liquid outlet (of secondary circuit)

13

heat-emitting liquid outlet (of primary circuit)

14

heat-absorbing liquid inlet (of secondary circuit)

15

primary circuit (of heat exchanger)

16

secondary circuit (of heat exchanger)

17

heat exchanger plate

18a

location for bending

18b

location for bending

18c

location for bending

18d

location for bending

20

middle plate

21

receiving portion (for receiving a connection member)

22

receiving portion (for receiving a connection member)

23

receiving portion (for receiving a connection member)

24

receiving portion (for receiving a connection member)

25

receiving portion (for temperature sensor connector)

26

extension portion of middle plate

30

heat exchanger portion of middle plate

31

heat-emitting liquid supply channel opening

32

heat-absorbing liquid discharge channel opening

33

heat-emitting liquid discharge channel opening

34

heat-absorbing liquid supply channel opening

40

end plate

41

receiving portion (for receiving a connection member)

42

receiving portion (for receiving a connection member)

43

receiving portion (for receiving a connection member)

44

receiving portion (for receiving a connection member)

45

receiving portion (for temperature sensor connector)

46

extension portion of end plate

50

heat-exchanger portion of end plate

51

end portion of heat-emitting liquid supply channel

52

end portion of heat-absorbing liquid discharge channel

53

end portion of heat-emitting liquid discharge channel

54

end portion of heat-absorbing liquid supply channel

55

temperature sensor portion

61

heat-emitting liquid supply channel

62

heat-absorbing liquid discharge channel

63

heat-emitting liquid discharge channel

64

heat-absorbing liquid supply channel

71

fastening means (hook)

72

fastening means (hook)

81

connector (to heat-emitting liquid supply line)

82

connector (to heat-absorbing liquid discharge line)

83

connector (to regulator 3)

83a

connector (to heat-emitting liquid discharge line)

84

connector (to heat-absorbing liquid supply line)

85

connector (temperature sensor)

90

connection member

91

connection portion (for middle and end plate)

92

connection portion (for connector)

120

middle plate

121

receiving portion (for receiving a connection member)

122

receiving portion (for receiving a connection member)

123

receiving portion (for receiving a connection member)

124

receiving portion (for receiving a connection member)

125

receiving portion (for temperature sensor connector)

126

extension portion of middle plate

130

heat exchanger portion of middle plate

131

heat-emitting liquid supply channel opening

132

heat-absorbing liquid discharge channel opening

133

heat-emitting liquid discharge channel opening

134

heat-absorbing liquid supply channel opening

140

heat exchanger portion of end plate

141

receiving portion (for connection piece)

142

receiving portion (for connection piece)

143

receiving portion (for connection piece)

144

receiving portion (for connection piece)

145

receiving portion (for temperature sensor connector)

146

extension portion of end plate

151

end portion of heat-emitting liquid supply channel

152

end portion of heat-absorbing liquid discharge channel

153

end portion of heat-emitting liquid discharge channel

154

end portion of heat-absorbing liquid supply channel

155

temperature sensor portion

161

heat-emitting liquid supply channel

161a

heat-emitting liquid supply channel section

161b

heat-emitting liquid supply channel section

162

heat-absorbing liquid discharge channel

162a

heat-absorbing liquid discharge channel section

162b

heat-absorbing liquid discharge channel section

163

heat-emitting liquid discharge channel

164

heat-absorbing liquid supply channel

200

snap fit indent

201

protrusion

202

recess

203

protrusion

204

recess

400

snap fit indent

401

recess

402

protrusion

403

recess

404

protrusion

[0036] Preferred embodiments of the invention are shown in the attached drawings:

Fig. 1

is a perspective view of a heating unit in accordance with an embodiment of the invention.

Fig. 2

is a bottom view of the end plate of the heating unit of Fig. 1.

Fig. 3

is a view of the end plate of the heating unit of Fig. 1.

Fig. 4

is a side view of the end plate of the heating unit of Fig. 1 from the left as seen in Fig. 3.

Fig. 5

is a bottom view of the middle plate of the heating unit of Fig. 1.

Fig. 6

is a view of the middle plate of the heating unit of Fig. 1.

Fig. 7

is a side view of the middle plate of the heating unit of Fig. 1 from the left as seen in Fig. 6.

Fig. 8

is a perspective view of the end plate of the heating unit of Fig. 1.

Fig. 9

is a schematic view of the heat exchanger of the heating unit of Fig. 1 or Fig. 16.

Fig. 10

is a perspective view of a connection member of the heating unit of Fig. 1 or Fig. 16.

Fig. 11

is a schematic view of cross section of a clinch joint of the heating unit in accordance with another embodiment of the invention, as shown in Fig. 16 and having an end plate as shown in Fig. 12 and a middle plate as shown in Fig. 14.

Fig. 12

is a view of an end plate of the heating unit of Fig. 16.

Fig. 13

is a flow chart of a heating unit of Fig. 1 or Fig. 16.

Fig. 14

is a view of a middle plate of a heating unit to be combined with the end plate of Fig. 12.

Fig. 15

is a perspective view of a heat exchanger plate to be used for manufacturing a heating unit in accordance with the invention.

Fig. 16

is a view of a heating unit in accordance with the invention comprising an end plate as shown in Fig. 12, a middle plate as shown in Fig. 14 and heat exchanger plates as shown in Fig. 15, wherein preferred locations are indicated at which clinch joints and/or bendings are to be made for fixing the heat exchanger plates into position before brazing them together.

[0037] In Figs. 1 to 10, Fig. 13 and Fig. 15 there is shown a first embodiment of a heating unit in accordance with the invention. In Fig. 12 there is shown an alternative end plate 140 of another embodiment of a heating unit in accordance with the invention (see Fig. 16) to be combined with a middle plate as shown in Fig. 14 and heat exchanger plates as shown in Fig. 15. The other components of this embodiment correspond to the embodiment as shown in Figs. 1 to 10. Accordingly essentially only the differences are described and reference is made to the description of the other embodiment. The reference numerals referring to the same or similar features are increased by 100 compared to the other embodiment.

[0038] Heating units typically comprises a plate heat exchanger, at least one regulator valve with one or more sensors and couplings for heat-emitting liquid, typically water from central heating plants, couplings for heat-absorbing liquid, typically utility water or liquid medium in a central heating plant. The plate heat exchanger comprises a primary circuit and a secondary circuit formed by a plurality of heat exchanger plates being configured in such a manner that separate flow passages are provided between adjoining heat exchanger plates for a heat-emitting liquid in the primary circuit and for a heat-absorbing liquid in the secondary circuit, respectively.

[0039] Plate heat exchangers lend themselves for use in connection with central heating plants and typically within the context of central heating plants for small units such as e.g. one-family houses, villas, flats, where it serves either as plate water heater for heating the utility water, or as plate water heaters for heating a liquid medium used in the central heating system of that unit.

[0040] Typically plate water heaters are used in a context where it is desired to have a central heating installation with a water heater having limited outer dimensions compared to a conventional water heater that often features a receptacle volume of about 100-200 litres of utility water. In cases where a plate water heater is used for heating utility water, cold utility water is conveyed into the secondary circuit of the plate heat exchanger. In the primary circuit hot central heating water is conveyed that emits the heat contained therein by heat transmission to the cold utility water in the secondary circuit, whereby the utility water is heated.

[0041] In cases where a plate heat exchanger is used for heating the liquid medium in a central heating plant, hot central heating water is conveyed through the primary circuit while emitting the heat contained therein by heat transmission to the heat-absorbing liquid in the secondary circuit. The heat-absorbing medium thus heated is then recycled to the central heating plant.

[0042] The heating unit in accordance with the embodiment of the invention as shown in Figs. 1 to 11 comprises a brazed plate heat exchanger 10 comprising a stack of heat exchanger plates 17 (see Fig. 15) defining a primary circuit 15 in which in use heat-emitting liquid (or fluid) such as water from central heating plants is flowing and a secondary circuit 16 in which heat-absorbing liquid such as utility water to be used for heating of a room or consumption.

[0043] The plate heat exchanger 10 comprises a heat-emitting liquid inlet 11 which is defined by holes in the individual plates (see Fig. 15) which are sealed against the secondary circuit 16 and open to the primary circuit 15 in a manner known to the skilled person. In the embodiments shown, the individual plates are brazed together by interposing a copper foil in between the individual plates before brazing at the locations where the brazing shall take place to provide the sealing. The plate heat exchanger 10 also comprises a heat-absorbing liquid outlet 12 open to the secondary circuit 16 and closed to the primary circuit 15, a heat-emitting liquid outlet 13 open to the primary circuit 15 and closed to the secondary circuit 16 and a heat-absorbing liquid inlet 14 open to the secondary circuit 16 and closed to the primary circuit 15.

[0044] The heat unit also comprises a middle plate 20 and an end plate 40 defining there between a heat-emitting liquid supply channel 61 for guiding heat-emitting liquid from a heat-emitting liquid supply line to the heat-emitting liquid inlet 11, a heat-emitting liquid discharge channel 63 for guiding heat-emitting liquid from the heat-emitting liquid outlet 13 to a heat-emitting liquid discharge line, a heat-absorbing liquid supply channel 64 for guiding heat-absorbing liquid from a heat-absorbing liquid supply line for supplying heat-absorbing liquid to the heat-absorbing liquid inlet 14, and a heat-absorbing liquid discharge channel 62 for guiding heat-absorbing liquid from the heat-absorbing liquid outlet 12 to a heat-absorbing liquid discharge line.

[0045] In the embodiment shown, the middle plate 20 comprises a flat heat exchanger portion 30 corresponding to the extensions of the heat exchanger plates. The middle plate is brazed to the last heat exchanger plate closing the heat exchanger at this side. At the other side a similar closing plate is provided in a manner known to the skilled person. The end plate 40 comprises a heat exchanger portion 50 into which indents are pressed defining the heat-emitting liquid supply channel 61, the heat-emitting liquid discharge channel 63, the heat-absorbing liquid supply channel 64 and the heat-absorbing liquid discharge channel 62. The indents have a semi-circular cross-section. It is clear that other cross-sections may be envisaged such as semi-oval or rectangular cross-sections. Semi-circular or semi-oval cross-sections are preferred because they can be better pressed into the plate.

[0046] The heat-emitting liquid supply channel 61 and the heat-absorbing liquid discharge channel 62 are adapted and arranged to enable heat transmission from heat-emitting liquid in the heat-emitting liquid supply channel 61 to heat-absorbing liquid in the heat-absorbing liquid discharge channel 62. Therefore channels 61, 62 are arranged next to each other in close distance over an essential part of their extension.

[0047] In the middle plate 20 there is a heat-emitting liquid supply channel opening 31 for connecting the heat-emitting liquid supply channel 61 with the heat-emitting liquid inlet 11 at the end portion 51, a heat-emitting liquid discharge channel opening 33 for connecting the heat-emitting liquid discharge channel 63 with the heat-emitting liquid outlet 13 at the end portion 53, a heat-absorbing liquid supply channel opening 34 for connecting the heat-absorbing liquid supply channel 64 with the heat-absorbing liquid inlet 14 at the end portion 54, and a heat-absorbing liquid discharge channel opening 32 for connecting the heat-absorbing liquid discharge channel 62 with the heat-absorbing liquid outlet 12 at the end portion 52.

[0048] The middle plate 20 comprises an extension portion 26. In the extension portion 26 there are receiving portions 21, 22, 23, 24 impressed. The end plate 40 comprises an extension portion 46 mating with extension portion 26. In the extension portion 46 there are receiving portions 41, 42, 43, 44 impressed. The receiving portions 21, 22, 23, 24 and 41, 42, 43, 44 are adapted and arranged that they form pairs of receiving portions for receiving respective connection members 90. In the embodiment as shown in Figs. 1 to 11 the connection members 90 are each brazed to the middle plate 20 and end plate 40 at a pair of the receiving portions 21, 41; 22, 42; 23, 43 and 24, 44, respectively.

[0049] A connection member 90 is shown in Fig. 10. The connection member 90 comprises a connection portion 91 onto which the middle plate 20 and the end plate 40 are brazed at respective receiving portions 21, 41; 22, 42; 23, 43 and 24, 44, respectively. At the opposite end of the connection member there is a connection portion 92 onto which a connector 81, 82, 83, 84 to the respective supply and discharge line (not shown) and the regulator 3, respectively, is mounted in a manner known to the skilled person.

[0050] The heat unit comprises a temperature sensor portion 55 (not shown in Fig. 1 but in Figs. 2, 3 and 4). A temperature sensor 4 (see Fig. 13) is located in the temperature sensor portion for sensing the temperature of the discharged heat-absorbing liquid of the secondary circuit. The middle plate 20 and the end plate 40 comprise a respective receiving portion 25, 45, respectively, wherein a connector 85 for connecting a signal line 8 (see Fig. 13) to the temperature sensor 4 is located.

[0051] On the end plate 40 there are provided fastening means 71, 72, each comprising a hook for fixing the heating unit to corresponding fastening means. In the embodiment shown in Figs. 1 to 10 the fastening means 71, 72 are embodied as hooks.

[0052] The middle plate 20 and the end plate 40 are brazed together. In order to ensure the correct alignment of the middle and the end plate before they are brazed together, there are three snap fits provided which are evenly spaced and located at one side of the plates 20, 40. The snap fit comprises a snap fit indent 200 in the middle plate 20 and a mating snap fit intent 400 in the end plate 40. If the snap fit is located in the plate heat exchanger portion 30, 50, respectively, as shown in the embodiment, the intents 200, 400 are provided such that the indents are facing away from the last plate of the plate heat exchanger. If the snap fit is provided in the extension portion 26, 46 of the middle plate and end plate, respectively, the indents can protrude to the plate heat exchanger also. The indents 200, 400 are dimensioned such that they smoothly fit into each other. Indent 200 may comprise protrusions and recesses. Indent 400 may comprise corresponding recesses and protrusions. They are dimensioned such that the indents 200 and 400 can snap into each other in order to provide a preliminary alignment before the brazing takes place.

[0053] The connector 83 is connected to a regulator 3. The regulator 3 is connected to a connection pipe having a connector 83a to be connected to a heat-emitting discharge line (not shown).

[0054] As shown in Fig. 13, in the heat-absorbing liquid supply channel 64 and/or the heat-absorbing liquid supply line there may be provided a safety valve 5, a closing valve 6 and/or a non-return valve 7.

[0055] The alternative embodiment as shown in Figs. 11 to 16 differs from the embodiment as shown in Figs. 1 to 10, 13 and 15 in that the heat-emitting liquid supply channel 161 and heat-absorbing liquid discharge channel 162 are curved such that they have a greater extension. Especially heat-emitting liquid supply channel 161 comprises a first heat-emitting liquid supply channel section 161a and a second heat-emitting liquid supply channel section 161b having a bent between each other and are extending in opposite directions. Similarly heat-absorbing liquid discharge channel 162 comprises a first heat-absorbing liquid discharge channel section 162a and a second heat-absorbing liquid discharge channel section 162b having a bent between each other and are extending in opposite directions. Due to this design the heat transfer between liquid supply channel 161 and liquid discharge channel 162 can be enhanced due to the greater extend of the channels. Having regard to the other features and components reference is made to the description of the other embodiment.

[0056] Additionally the alternative embodiment as shown in Figs. 11 to 16 differs from the embodiment as shown in Figs. 1 to 10, 13 and 15 in that the end plate 140 and the middle plate 120 are clinched together by means of clinch joints 1. The locations of the clinch joints 1 are indicated in Figs. 12 and Fig. 14 although the clinch joints are made only at the time the end plate and the middle plate are fixed together by clinching in order to define the correct alignment before the brazing step takes place.

[0057] In Figs. 12 and 14 the positions for the clinch joints 1 are indicated on the end plate 140 and the middle plate 120.

[0058] The clinch joints 1 are made by punching two sheet of material (i.e. the end plate and the middle plate) into a die resulting in a clinch joint 1. An exemplary section of a clinch joint is shown in Fig. 11.

[0059] In Fig. 11 a clinch joint is shown, wherein the punch is made from the end plate in the direction of the middle plate 120, wherein a die (not shown) has been provided beneath the middle plate. It is clear that the punch can also been made the other way round, i.e. from the middle plate into the direction of the end plate resulting to a similar form as shown in Fig. 11, wherein the clinch joint faces away from the end plate.

[0060] The outer form of the clinch joint 1 corresponds to the form of the die (middle plate 120) and the punching stamp (end plate 140). By the clinching process the punch and the corresponding die forces the sheet material of the end plate 140 and the middle plate 120 into interlocking interference. As shown in Fig. 11 there are protrusions 201, 203 of the middle plate 120 protruding into corresponding recesses 401, 403 of the end plate 140. Similary there are protrusions 402, 404 of the end plate 140 protruding into corresponding recesses 202, 204 of the middle plate 120.

[0061] Instead of using the clinching technique it may be possible to adjoin the end plate with the middle plate by other means, as for instance using rivets, bolts etc. or gluing the plates together. However the clinching is the preferred mode of fixing the relative position of the end plate and the middle plate.

[0062] As shown in Fig. 12, the clinch joints are to be made preferably in areas outside the area where the heat exchanger plates are to be located. As shown two clinch joint 1 are to be located on the left hand side on each side of receiving portion 145. Another two clinch joints are located on the right hand side on each side of receiving portion 145. At the bottom side there are two clinch joints located in between receiving portions 141 and 142 as well as in between receiving portions 142 and 144. Different numbers and locations of clinch joints 1 are envisaged. For instance there may be three or two clinch joints provided only.

[0063] The preferred method for manufacturing a heating unit in accordance with the invention is as follows:

a) The middle plate 20, 120 is pressed, preferably in two steps, i.e. step a1) to form the channels and step a2) to calibrate for the connection members.

b) The end plate 40, 140 is pressed, preferably in two steps, i.e. step b1) to form the channels and step b2) to calibrate for the connection members.

c) The middle plate, the end plate and all connection members are pressed together and clinch joints are provided to clinch the middle plate to the end plates. Preferably copper foils are placed in between the middle plate, the end plate and the connection members at the beginning of this step to be used in the later brazing step. The clinching ensures the correct alignment of the parts to be brazed together in the later brazing step.

d) The heat exchanger plates are stacked together and bendings are provided preferably at locations 18a, 18b, 18c, 18d for bendings as shown in Fig. 16 in order to ensure the correct alignment of the heat exchanger plate stack. It is clear that more of less bendings may be provided in accordance with the invention as long as the correct alignment of the heat exchanger plate stack is ensured. The heat exchanger plate stack is then placed onto the middle plate opposite to the end plate clinched thereto.

e) The assembled end plate and middle plate and connection members and the heat exchanger plate stack is then brazed together such that an inseparable heating unit is obtained.

Claims

1. Heating unit comprising

- a plate heat exchanger (10) having a plurality of heat exchanger plates combined to form a plate stack defining flow passages of a primary circuit (15) having a heat-emitting liquid inlet (11) and a heat-emitting liquid outlet (13) and flow passages of a secondary circuit (16) having a heat-absorbing liquid inlet (14) and a heat-absorbing liquid outlet (12),

- a heat-emitting liquid supply channel (61) for guiding heat-emitting liquid from a heat-emitting liquid supply line to the heat-emitting liquid inlet (11),

- a heat-emitting liquid discharge channel (63) for guiding heat-emitting liquid from the heat-emitting liquid outlet (13) to a heat-emitting liquid discharge line,

- a heat-absorbing liquid supply channel (64) for guiding heat-absorbing liquid from a heat-absorbing liquid supply line for supplying heat-absorbing liquid to the heat-absorbing liquid inlet (14), and

- a heat-absorbing liquid discharge channel (62) for guiding heat-absorbing liquid from the heat-absorbing liquid outlet (12) to a heat-absorbing liquid discharge line,
wherein the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62) are adapted and arranged to enable heat transmission from heat-emitting liquid in the heat-emitting liquid supply channel (61) to heat-absorbing liquid in the heat-absorbing liquid discharge channel (62),
characterised in that the heating unit comprises a middle plate (20) and an end plate (40) having openings (31, 32, 33, 34) and/or pressed indents defining the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62).

2. Heating unit according to claim 1, wherein the middle plate (20) has openings (31, 32, 33, 34) and the end plate has pressed indents defining the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62).

3. Heating unit according to any of the preceding claims, wherein the middle plate (20) and the end plate (40) have openings (31, 32, 33, 34) and/or pressed indents defining the heat-emitting liquid discharge channel (63) and the heat-absorbing liquid supply channel (64).

4. Heating unit according to any of the preceding claims, wherein the heating unit comprises connection members (90) for connecting the channels (61, 62, 63, 64) to connectors (81, 82, 83, 84) for connecting the channels (61, 62, 63, 64) to the respective supply and discharge lines, wherein preferably the middle plate (20) comprises pressed indents defining receiving portions (21, 22, 23, 24) for the connection members (90) and/or the end plate (40) comprises pressed indents defining receiving portions (41, 42, 43, 44) for the connection members.

5. Heating unit according to any of the preceding claims, wherein the heating unit comprises at least one snap fit (1) defining the relative position of the middle plate (20) with respect to the end plate (40).

6. Heating unit according to any of the preceding claims, wherein the heating unit comprises at least one or a plurality of clinch joints (1) defining the relative position of the middle plate (20) with respect to the end plate (40).

7. Heating unit according to any of the preceding claims, wherein the heating unit comprises at least one snap fit or a plurality of snap fits defining the relative position of the middle plate (20) with respect to the end plate (40), wherein the or each snap fit preferably comprises a snap fit indent (200) provided in middle plate (20) and a snap fit indent (400) provided in the end plate (40).

8. Heating unit according to any of the preceding claims, wherein the middle plate (20) and the end plate (40) are brazed together.

9. Heating unit according to any of the preceding claims, wherein portions of the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62) are arranged next to each other.

10. Heating unit according to any of the preceding claims, wherein the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62) are extending from the top portion of the middle plate (20) and the end plate (40) to the bottom portion of the middle plate (20) and the end plate (40).

11. Heating unit according to any of the preceding claims, wherein the heat-emitting liquid supply channel (61) and the heat-absorbing liquid discharge channel (62) are curved.

12. Method for manufacturing a heating unit according to any of the preceding claims, wherein the plates of the plate heat exchanger (10) and the middle plate (20) and the end plate (40) are brazed together.

13. Method according to claim 12, wherein the middle plate (20) and the end plate (40) comprise respective receiving portions (21, 22, 23, 24, 41, 42, 43, 44) for connection members (90) and wherein the middle plate (20), the connection members (90) and the end plate (40) are brazed together.

14. Method according to claim 12 or 13, wherein all parts to be brazed together are brazed together in one brazing step.

15. Method according to any of claims 12 to 14, wherein respective copper foils are placed between all parts to be brazed together before the brazing step.

Drawing