FR3081280A1 - HEATING MODULE FOR HEATING DEVICE FOR MOTOR VEHICLE - Google Patents

Abstract

Electric heating module, for electric heating device, the module (12) comprising a heating unit (20), said unit (20) comprising: • one or more heating elements (22), preferably of the type with a coefficient of positive temperature, arranged to generate heat when they are traversed by a current, • electrodes (24) in contact with the heating body (22) for supplying said heating body (22) with current, the module (12) further comprising: - a thermal envelope (26) arranged to conduct the heat generated by the heating body (22), - a layer of electrical insulation between each electrode (24) and the envelope (26), characterized in that the thermal envelope (26) comprises at least a first piece (28a) and a second piece (28b) assembled together.

Description

The present invention relates to a heating module for a heating device for a motor vehicle, in particular for a high-voltage heating device for an electric or hybrid motor vehicle.

It is known to provide a motor vehicle with a heating device. Such a heating device can in particular be used to heat air before it enters the passenger compartment of the motor vehicle.

In the context of an electric motor vehicle, in particular, it is known to use a so-called "high voltage" heating device. Such a heating device is conventionally supplied with a voltage between 100 V and 1000 V.

This heating device can in particular be integrated into a heating, ventilation and / or air conditioning installation (called "HVAC unit" from the English "heating, ventilation and air-conditioning"). In this case, the heating device is for example arranged downstream of the cooling liquid heating core.

Such a heating device conventionally comprises heating units, each received in a tube, the tubes being in contact with fins aimed at improving the heat exchange with the air to be heated. Each heating unit comprises for example one or more heating bodies, electrically powered by two electrodes, the whole of the heating body (s) and the two electrodes being covered by a layer of electrical insulator. The heating element is for example a stone made of a resistance material with a positive temperature coefficient (or PTC, from the English "positive temperature coefficient").

For the manufacture of the heating device, it is therefore necessary that each tube is high enough to allow insertion into the interior of a heating unit. However, at the end of the manufacturing process, it is necessary that the initial height of the tube has been reduced in order to sandwich the heating unit, this in order to allow, in particular, correct electrical contacts between the electrodes and the or the heaters and good general heat transfer.

To do this, it is known to press the tube in the direction of its height. However, such pressing is difficult to control to allow the heating unit to be sandwiched in the tube, without damaging the components of this heating unit.

In addition, the final shape of the tube is not well controlled. As a result, it is difficult to ensure satisfactory thermal contact between the heating unit and the tube. There are still spaces between the tube and the heating unit. These spaces contain air which isolates the heating unit, thus deteriorating the heat transfer between the heating unit and the air flow to be heated. The performance of the device is affected.

An object of the invention is to provide a heating module for a heating device for a motor vehicle, comprising a thermal envelope, said envelope being in particular intended to receive a heating unit and, if necessary, to be thermally connected to fins. , said thermal envelope making it possible to facilitate the manufacture of a heating device for a motor vehicle.

To this end, the invention relates to an electric heating module, for an electric heating device, the module comprising a heating unit, said unit comprising:

o one or more heating bodies, preferably of the positive temperature coefficient type, arranged to generate heat when a current flows through them, o electrodes in contact with the heating body to supply said heating body with current , the module further comprising:

- a thermal envelope arranged to conduct the heat generated by the heating body,

- a layer of electrical insulator between each electrode and the envelope, characterized in that the thermal envelope comprises at least a first part and a second part assembled together.

The final form of the heating module after assembly is, thanks to the object of the invention, perfectly known and mastered, which limits the risk of formation of air pockets between the thermal envelope and the heating unit. The invention thus ensures better thermal contact between the heating unit and the thermal envelope. The overall thermal performance of the module is thus improved.

In addition, no pressing operation of the thermal envelope is necessary to allow the heating unit to be sandwiched. The risk of damaging said heating unit and / or the electrical insulation by this operation is thus eliminated.

In general, the shaping of the envelope and therefore the manufacture of the heating module is simplified.

The module can also include one or more of the following characteristics, taken separately or in combination:

at least one of the first and second parts is configured to be deformed, in particular configured to be deformed plastically or elastically, so as to enclose the other part with which it is assembled, the thermal envelope surrounds the heating unit over substantially its entire periphery , the first and second parts are assembled together in a detachable manner, the first and second parts are assembled together so as to keep tight between said first and second parts, the heating body, the electrodes and the layer of electrical insulator, the first and second parts each comprise at least one fastening element, the fastening element of the first part is arranged to cooperate with the fastening element of the second part to assemble the first and second parts together, the body of heater includes one or more resistive elements, including a or several ceramics, the module comprises fins configured to increase the heat exchanges between the thermal envelope and the air to be heated, the fins are brazed or glued to the thermal envelope, so as to ensure thermal transfer by conduction between the 'envelope and the fins, each of the first and second parts comprises at least one main face which is parallel to the main face of the other part with which it is assembled, the main faces of the first and second parts are arranged on the side and d other of the heating unit, the main faces are facing the heating body, the electrodes are held tight against the heating body between the main faces, the main faces of the first and second parts are delimited by a main plate respectively of the first and of the second part, each main plate ensuring the thermal transfer p ar conduction between the heating unit and the fins, the main faces of the first and second pieces have the same surface area, the main faces of the first and second pieces are flat, the fins are brazed on the main plates, a main plate is rectangular , at least one of the first and second parts comprises a rim, the rim extends over at least part of the periphery of the main face, the rim extends perpendicular to the main face, the thermal envelope comprises a member capable of ensure a seal between the first and second parts, in particular a seal.

According to yet another aspect, the invention relates to a method for manufacturing an electric heating module for a heating device for a motor vehicle comprising the step consisting in:

deform, in particular deform plastically or elastically one of the first and second parts so as to enclose the other part and assemble the first and second parts therebetween.

According to a nonlimiting embodiment, the method comprises a step consisting in:

assemble the first and second pieces so as to keep tight between them, the heating body, the electrodes and the layer of electrical insulation.

In a first embodiment, the module can also include one or more of the following characteristics, taken separately or in combination:

the first part is configured to be plastically deformed so as to enclose the second part, the parts are crimped to each other.

The crimping of the parts together means that soldering is not used to assemble the parts together. The heating module is thus in no way affected thermally during this assembly operation, which further reduces the risk of damage to a component of this module.

In this first embodiment, the module can also include one or more of the following characteristics, taken separately or in combination:

the first part forms a receptacle for the heating unit, the receptacle comprises an opening for inserting the heating unit, the second part forms a cover which adapts to the receiving opening, the first part extends at least partially through an orifice in the second part, on either side of the second part, the fastening element of the first part comprises at least one extension of material, otherwise called a tenon, the tenon takes the shaped like a tongue, the post is configured to be plastically deformed so that the first part encloses the second part, the fastening element of the second part comprises at least one orifice cut in the main plate of the second part , the post cooperates with the orifice to assemble the first and second parts therebetween, the post is arranged to keep tight between the first and the second part the co heating rps, the electrodes and the layer of electrical insulator, the post extends through said orifice of the second part, on either side of the second part, in particular on either side of the plate main part of the second part, the tenon further extends along the main plate of the second part, in particular on a distal portion of said tenon, the first part comprises several tenons around its periphery, the tenons are regularly spaced apart from one another. others, the second part has several orifices around its periphery, the orifices are regularly spaced from one another, so that each of the orifices cooperates with a tenon.

Such a distribution of the studs and orifices makes it possible to distribute the bonding forces between the first and the second part around the periphery of the thermal envelope. The final shape of the heating module after assembly is thus more controlled and the risk of air pockets forming between the casing and the heating unit is more limited.

The invention thus ensures better thermal contact between the heating unit and the thermal envelope. The overall thermal performance of the module is thus improved.

In this first embodiment, the module can also include one or more of the following characteristics, taken separately or in combination:

the rim extends over at least three sides of the main face of the first part, the opening for inserting the heating unit is delimited by the rim, the studs are produced in the form of slot cutouts on the flange.

The manufacture of the first part, and in particular the production of the fastening elements thereof, is therefore particularly simple.

In this first embodiment, the method according to the invention may include one or more of the following characteristics, taken alone or in combination:

plastically deform the first piece so as to enclose the second piece, insert the first piece at least partially into an opening in the second piece, insert the post of the first piece into an opening of the second piece, bend the post so that keep the heating body, the electrodes and the layer of electrical insulation between the first part and the second part.

In a second embodiment, the module can also include one or more of the following characteristics, taken separately or in combination:

the first and second parts are configured to be assembled together by elastic deformation of at least one of the first and second parts so that one of the first and second parts encloses the other part to assemble the first and second parts between them, the fastening element of the second part comprises at least one protusion on a rim of the second part, the protusion being configured to ensure anchoring of the second part in at least one recess of the fastening element of the first part, the recess is formed in a rim of the first part, the fastening elements of the first and second parts cooperate with each other by complementarity of shape, the protusion comprises a rib, the rib is rectilinear, the recess comprises at least a groove, the groove is straight, the fastening element of the first part comprises the at least one groove e t the fastening element of the second part comprises the at least one rib, the groove and the rib cooperating with each other, in particular by form complementarity, to assemble the first and second parts together, the at least one groove extends along at least one edge of the first piece, the at least one rib extends along at least one edge of the second piece, the first piece has a first edge and a second edge, the first and second rims of the first piece extend along two opposite sides of the main face of the first piece, the first and second edges of the first piece each have two grooves, a rim of the first piece has an end groove and a groove central, the central groove extending between the extreme groove and the periphery of the main face, the central groove extends parallel to the extreme groove, the second me piece has a first flange and a second flange, the first and second edges of the second piece extend along two opposite sides of the main face of the second piece, the first and second edges of the second piece each have a rib.

In this second embodiment, the method according to the invention may include one or more of the following characteristics, taken alone or in combination:

elastically deform the second part and / or the first part so that the second part encloses the first part, insert the ribs of the second part in the end groove of the first part, preferably by guiding in translation the rib in the extreme groove, exert pressure simultaneously on the main plates of the first and second parts so as to elastically deform the first and / or the second part until insertion of the rib in the central groove.

It is possible, in this second embodiment, to perform the soldering of the fins on the envelope before the latter surrounds the heating unit. The heating unit is therefore not subjected to any thermal stress.

The invention also relates to a heating device for a motor vehicle comprising a plurality of heating modules as described above in all of their combinations.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which:

- Figure 1 shows a side view of an example of a heating device according to the invention;

- Figure 2 shows an assembled view of a heating module according to a first embodiment;

- Figure 3 shows an exploded view of the heating module according to the first embodiment;

- Figure 4 shows an enlarged view of the cover according to the first embodiment;

- Figure 5 shows an assembled view of a heating module according to a second embodiment;

- Figure 6 shows an exploded view of the heating module according to the second embodiment;

- Figure 7 shows a sectional view of the heating module according to the second embodiment in a first assembly position;

- Figure 8 shows a sectional view of the heating module according to the second embodiment in a second assembly position.

FIG. 1 shows, in side view, an example of a high-voltage heating device 10 for a motor vehicle. Such a heating device 10 is used in particular in electric and hybrid motor vehicles. Such a heating device 10 is for example supplied with a current whose voltage is between 100 V and 1000 V. Such a heating device 10 comprises a plurality of heating modules 12.

The electrical supply of the heating modules 12 can be carried out by means of an electronic control unit (not shown).

The heating module 12 essentially comprises a heating unit 20. More specifically, the heating unit 20 comprises, in accordance with the invention, a heating body 22, sandwiched between two electrodes 24, a layer of electrical insulator (not shown) surrounding the assembly formed by the heating body 22 and the two electrodes 24 and a thermal envelope 26 arranged to conduct the heat generated by the heating body 22. In the example illustrated, the thermal envelope 26 surrounds the heating unit 20 over substantially its entire periphery. The heating body 22 generates heat by Joule effect when a current flows through it.

The thermal envelope 26 is for example in one of the metals among aluminum, copper, brass. The thermal envelope 26 can be made of a single metal or can be made of different metals or alloys. The thermal envelope 26 serves as a thermal interface between in particular the heating unit 20 and the other elements of the heating device 10 as well as the air to be heated.

The function of the electrical insulating layer is to avoid a short circuit through the thermal envelope 26 between the various elements of the heating unit 20. The electrical insulating layer is preferably made of a material which is a good conductor of heat, in order to allow a significant heat exchange between the heating body 22 and the air to be heated surrounding the thermal envelope 26. For example, the layer of electrical insulator is made of one of the materials among the alumina or a polyimide-type synthetic material, Kapton®. For reasons of clarity of the figures, this layer of electrical insulation is not shown.

The heating body 22 is for example a stone made of a resistance material with a positive temperature coefficient, such as a ceramic. Thus, the resistance of the heating body 22 increases with the temperature of this heating body 22.

The heating unit 20 can comprise several heating bodies 22.

The electrodes 24 can in particular be made of one of the metals among aluminum, copper, brass.

In the example illustrated, the module comprises fins configured to increase the heat exchanges between the thermal envelope and the air to be heated. One can in particular choose as shape for the fins 14 any geometry allowing for example to increase the heat exchanges with the air to be heated. The fins 14 are, in the example illustrated, brazed to the thermal envelope 26. According to an alternative embodiment, the fins can be bonded to the envelope 26.

The thermal envelope 26 is now described in more detail.

The thermal envelope 26 comprises a first part 28a and a second part 28b. The first and second parts 28a; 28b are detachably assembled together. It will be understood by this that the first part 28a can be separated from the second part 28b without causing even partial destruction of the first and / or the second part 28a; 28b. In particular, the first part 28a and / or the second part 28b are configured to be plastically and / or elastically deformed, so as to enclose the other part 28a; 28b with which it is assembled so as to assemble the first and second parts 28a; 28b between them.

The first and second parts 28a; 28b keep tight between them, the heating body 22, the electrodes 24 and the layer of electrical insulator. Intimate contact between the different elements of the heating module 12 is advantageous in order to promote the conduction of the heat generated by the heating body 22 towards the outside of the heating module 12. The heat generated by the heating body 22 is thus conducted efficiently through the electrodes 24 and the layer of electrical insulator to the thermal envelope 26, which dissipates the heat in the air to be heated. In particular, the heat is transmitted by conduction from the thermal envelope 26 to the fins 14, then and evacuated by convection, natural or forced, between the surface of the fins 14 and the air to be heated.

In order to achieve a detachable assembly of the first and second parts 28a; 28b, these include fixing elements arranged to cooperate with each other. Thus, a fastening element of the first part 28a cooperates with at least one fastening element of the second part 28b.

Each of the first and second parts 28a; 28b has at least one main face 30a; 30b which is parallel to the main face 30a; 30b in the other room 28a; 28b with which it is assembled. The main faces 30a; 30b of the first and second parts 28a; 28b are arranged on either side of the heating unit 20. In the example illustrated, the main faces 30a; 30b are opposite the heating body 22 and the electrodes 24 are held tight against the heating body 22 between these main faces 30a; 30b.

The main face 30a of the first part 28a is delimited by a main plate 32a of the first part 28a. Similarly, the main face 30b of the second part 28b is delimited by a main plate 32b of the second part 28b. It will be understood here that each of the main plates 32a; 32b constitutes a face of a plate, called the main plate, the thickness of which is negligible compared to the other dimensions, the plate thus constituting a wall of the first and second part 28a respectively; 28b. The fins 14 are brazed or glued to each of the main plates 32a; 32b, the main plates 32a; 32b thus ensuring thermal transfer by conduction between the heating unit 20 and the fins 14.

In the example illustrated, the main faces 30a; 30b of the first and second parts 28a; 28b therefore comprise a flat face, of a rectangular plate or wall of the first part 28a and the second part 28b respectively.

H is possible to provide a member for sealing between the first and second parts 28a; 28b, for example a seal 34.

According to a first embodiment illustrated in FIGS. 2 to 4, the first part 28a is configured to be plastically deformed so as to grip the second part 28b. The first and second parts 28a; 28b are, in this embodiment, crimped to each other.

The crimping of the first and second pieces 28a; 28b between them makes it possible not to have recourse to welding to assemble the first and second parts 28a; 28b between them. The heating module 12 is thus in no way affected thermally during an assembly operation, which further reduces the risk of damage to a component of this module 12.

As visible in FIG. 3, the first part 28a forms a receptacle for the heating unit 20, the receptacle has an opening 36 for the insertion of the heating unit 20. The second part 28b forms a cover which s' adapts to said opening 36.

The first part 28a in particular has a rim 38 which extends over a part of the periphery of the main face of said first part 28a, perpendicular to said first part 28a. The rim 38 extends in the example illustrated on at least three sides of the periphery of the main face 30a of the first part 28a. The rim 38 thus delimits the opening 36 of the receptacle for the insertion of the heating unit 20. The main plate 32a of the first part 28a forms a bottom for the receptacle.

In this embodiment, the fastening elements of the first part 28a are in the form of tenons 40, each tenon 40 taking, in this embodiment, the form of a tongue. A lug 40 of the first part 28a is configured to be plastically deformed so that the first part 28a encloses the second part. The pins 40 are advantageously made in the form of slots in the rim 38. This further simplifies the manufacture of the first part 28a, and in particular the manufacture of the fastening elements.

The fastening elements of the second part 28b are in the form of holes 42 (not shown in FIG. 3) cut from the main plate 32b of the second part. The pins 40 cooperate with the orifices 42 in order to assemble the first and second parts 28a; 28b between them. In such an assembly, the pins 40 are arranged to keep clamped between the first and the second part 28a; 28b the heating body 22, the electrodes 24 and the layer of electrical insulator.

According to the first embodiment, the pins 40 extend through said orifice of the second part 28b, on either side of the second part 28b, in particular on either side of the main plate 32b of the second room 28b. On their distal portion, the pins 40 extend in particular along the main plate 32b of the second part 28b.

According to the first embodiment, pins 40 are arranged on the periphery of the first part 28a and are spaced regularly from each other. The orifices 42 of the second part 28b are arranged on the periphery of the main plate 32b of the second part 28b and are spaced regularly from one another so as to each cooperate with one of the tenons 40.

Such a distribution of the pins 40 and the orifices 42 makes it possible to distribute the connection forces between the first and the second part 28a; 28b on the periphery of the thermal envelope 26. The final shape of the heating module 12 after assembly is of the kind of advantage controlled and the risk of the formation of air pockets between the thermal envelope 26 and the unit heating 20 is more limited.

The invention thus makes it possible to ensure better thermal contact between the heating unit 20 and the thermal envelope 26 and the overall thermal performance of the module 12 is improved.

A method of manufacturing the heating module 12 according to this first embodiment consists in plastically deforming the first part 28a so as to enclose the second part 28b. In particular, the method according to this first embodiment consists in assembling the first and second parts 28a; 28b so as to keep the heating body 22, the electrodes 24 and the layer of electrical insulation tightly connected to each other, in particular insert the pins 40 of the first part 28a into the orifices 42 of the second part 28b then flex said pins 40 so as to keep tight between the first part 28a and the second part 28b the heating body 22, the electrodes 24 and the layer of electrical insulator.

According to a second embodiment illustrated in Figures 5 to 8, the first and second parts 28a; 28b are configured to be assembled together by elastic deformation of at least one of the first and second parts 28a; 28b so that one of the first and second parts 28a; 28b encloses the other room 28a; 28b with which it is assembled.

In this embodiment, each of the first and second parts 28a; 28b includes first and second flanges 38a; 38b; 39a; 39b. The first edge 38a; 39a extends on a first side of the periphery of the main face 30a; 30b of each of the first and second parts 28a, respectively; 28b and the second rim 38b; 39b extends over a second side of the periphery of said main face 30a; 30b, the second side being opposite the first side.

A fastening element of the second part 28a is in the form of a rib 44 on a flange 39a; 39b of the second part 28b, said rib 44 thus forming a protusion on the rim 39a; 39b of the second room 28b. The rib 44 is configured to anchor the second part 28b in at least one recess formed in a flange 38a; 38b of the first part 28a. The recesses are, in the example illustrated, constituted by two parallel grooves 46E; 46C formed in each of the flanges 38a; 38b of the first part 28a.

As illustrated in the sectional views of Figures 7 and 8, the flanges 38a; 38b of the first part 28a therefore each comprise two grooves 46E; 46C and ledges 39a; 39b of the second part 28b each comprise a rib 44. In particular, each of the flanges 38a; 38b of the first part 28a has a first groove, called the extreme groove 46E, extending along the rim 38a; 38b, near the distal free end of said flange 38a; 38b. Each of the flanges 38a; 38b of the first part 28a further comprises a second groove, called central groove 46C, extending along said rim 38a; 38b, between the extreme groove 46E and the periphery of the main face 30a. The central groove 46C extends between the extreme groove 46E and the edge which intersects between the flange 38a; 38b and the main plate 32a of the first part.

Each of the ribs 44 is in the example illustrated rectilinear and cooperates by complementary shape with at least one groove 46E; 46C, itself straight.

A method of manufacturing the thermal envelope 26 according to this second embodiment consists in elastically deforming the second part 28b and / or the first part 28a so that the second part 28b encloses the first part 28a. In particular, the method consists in a first step of inserting the ribs 44 of the second part 28b in the end grooves 46E of the first part 28a, preferably by guiding in translation each of the ribs 44 in the corresponding end groove 46E, placing the heating module 12 in a first assembly position. The method then consists in a second step of exerting pressure simultaneously on the main plates 32a; 32b of the first and second parts 28a; 28b so as to elastically deform the first and / or the second part 28b until each of the ribs 44 is inserted into the corresponding central groove 46C, in a second assembly position of the heating module 12. In this second step, the ribs 44 are dislodged from the extreme grooves under the effect of the pressure and the flanges 39a; 39b of the second room move away from each other accordingly. According to a particular embodiment, at least one of the main plates 32a; 32b are also bent under the effect of the simultaneous pressure on the main plates 32a; 32b. During this second step, the main faces 30a; 30b move towards each other until the ribs 44 are inserted into the central grooves 46C, in the second assembly position of the heating module 12.

The assembly of the thermal envelope 26 and the heating module 12 is thus particularly simple. In addition, this embodiment has the advantage that it is possible to braze the fins 14 on the thermal envelope 26 before the latter surrounds the heating unit 20. The heating unit 20 n 'is thus subjected to no thermal stress during the brazing of the fins 14 on the first and second parts 28a; 28b of the thermal envelope 26, said parts 28a; 28b can be assembled later in this brazing step, in accordance with the manufacturing method according to the second embodiment.

Claims (10)

1. Electric heating module, for an electric heating device, the module (12) comprising a heating unit (20), said unit (20) comprising: • one or more heating bodies (22), preferably of the type with a positive temperature coefficient, arranged to generate heat when they are traversed by a current, • electrodes (24) in contact with the heating body (22 ) to supply said heating body (22) with current, the module (12) further comprising: - a thermal envelope (26) arranged to conduct the heat generated by the heating body (22), - a layer of electrical insulator between each electrode (24) and the envelope (26), characterized in that the thermal envelope (26) comprises at least a first part (28a) and a second part (28b) assembled between they. 2. Module according to the preceding claim characterized in that the first and second parts (28a; 28b) are assembled together in a detachable manner. 3. Module according to one of the preceding claims characterized in that at least one of the first and second parts (28a; 28b) is configured to be deformed, in particular configured to be deformed plastically or elastically, so as to enclose the other part (28a; 28b) with which it is assembled. 4. Module according to one of the preceding claims, characterized in that it comprises fins (14) configured to increase the heat exchanges between the thermal envelope (26) and the air to be heated. 5. Module according to one of the preceding claims, characterized in that each of the first and second parts (28a; 28b) comprises at least one main face (30a; 30b) which is parallel to the main face (30a; 30b) of the other part (28a; 28b) with which it is assembled. 6. Module according to one of the preceding claims, characterized in that the first and second parts (28a; 28b) each comprise at least one fixing element, the fixing element of the first part (28a) being arranged to cooperate with the fastening element of the second part (28b) to assemble the first and second parts (28a; 28b) together. 7. Module according to claim 6, characterized in that the fastening element of the first part comprises at least one stud (40) and the fastening element of the second part comprises at least one orifice (42), the tenon (40) cooperating with the orifice (42) to assemble the first and second parts (28a; 28b) therebetween. 8. Module according to claim 6, characterized in that the fastening element of the first part comprises at least one groove (46E; 46C) and the fastening element of the second part comprises at least one rib (44), the groove (46E; 46C) and the rib (44) cooperating with each other, in particular by complementary shape, to assemble the first and second parts (28a; 28b) between them. 9. A heating device for a motor vehicle comprising a plurality of heating modules (12) according to any one of the preceding claims. 10. Method of manufacturing an electric heating module according to one of the preceding claims comprising the steps consisting in: plastically or elastically deform one of the first and / or second pieces (28a; 28b) so as to grip the other piece (28a; 28b) and assemble the first and second pieces (28a; 28b) together.