LU502910B1

LU502910B1 - Heat-radiating assembly with heat shield

Info

Publication number: LU502910B1
Application number: LU502910A
Authority: LU
Inventors: Florian Cavaiotti; Vanessa Georges; Nicolas Protin
Original assignee: Katcon Global Sa
Priority date: 2022-10-17
Filing date: 2022-10-17
Publication date: 2024-04-17

Abstract

A heat-radiating assembly comprises a heat-radiating system with a housing and a heat shield assembly being arranged around said housing, said heat shield assembly comprising at least one heat shield opening through which at least one mounting bracket and/or sensor device, which is arranged on and extending outwards from said housing, extends outward of said heat shield assembly. The heat shield opening is dimensioned so that a circumferential gap is formed between said heat shield assembly and the at least one mounting bracket and/or sensor device. A pad of a compressible heat insulating material is arranged in said heat shield opening around said at least one mounting bracket and/or sensor device so as to entirely fill the circumferential gap between said heat shield assembly and the at least one mounting bracket and/or sensor device and is hold in place by compression of said pad of compressible heat insulating material.

Description

Heat-radiating assembly with heat shield

Technical field

[0001] The present invention generally relates to a heat-radiating assembly of an engine or a machinery, and more particularly to an exhaust gas aftertreatment system.

Background of the Invention

[0002] Exhaust lines are used in vehicles for routing exhaust gas generated by a fuel-burning engine to the atmosphere surrounding the vehicle. It is required to reduce pollutant(s) in the exhaust to an environmentally-acceptable level or form before the exhaust is released to the surrounding atmosphere. Accordingly, there is a requirement to provide an exhaust line for a vehicle with an exhaust gas aftertreatment assembly that operates to reduce pollutant(s) of an exhaust to an environmentally-acceptable form.

[0003] An exhaust treatment assembly typically comprises one or more exhaust gas treatment components such as one or more catalytic converters and/or fuel particulate filters which are arranged within a common housing. Due to the high temperature of the exhaust gases, aftertreatment systems heated up to very high temperatures. As most aftertreatments are located close to the engine (to take benefit of hot gases and facilitate chemical reaction), they are also exposed to flammable liquids (like fuel, motor oil, coolant) which can ignite in contact with high temperature surfaces thereby causing a fire to start. To prevent that, it is important to make sure flammable liquids are not getting in touch with hot surfaces in case of failure. The exhaust treatment assembly therefore usually includes a heat shield assembly with an external encapsulating material arranged around the housing, the space between the housing and the encapsulating material being filled with a mat of thermally insulating material. This heat shield assembly effectively reduces the temperature at the outer surface, thereby preventing liquids to ignite and cause fire.

[0004] However, it is not possible to avoid openings in the direct encapsulation of the heat shield assembly. In fact, the exhaust treatment assembly comprises one or more mounting brackets which are mounted on the housing of the exhaust gas treatment component and which are used to secure the exhaust treatment assembly to the vehicle structure or the engine. Furthermore, the assembly usually includes one or more sensor devices which are mounted in ports of the housing and used to monitor the catalytic reaction or the efficiency thereof. Both the mounting brackets and the sensor devices extend outwards from the housing and penetrate the heat shield assembly through openings arranged therein to protrude outside of the assembly.

[0005] In order to allow a proper installation of the encapsulation and due to process tolerances, the heat shield openings are larger than the corresponding cross section of the mounting brackets or the sensor devices, so that a circumferential gap is formed between said heat shield assembly and the mounting bracket and/or sensor device. Due to this gap, the openings let some small surfaces of the housing exposed to liquid. In most cases, this is not considered as an issue because liquid will not stay in the corresponding area and the risk the liquids to ignite is very low. In some cases however, e.g. if the opening is orientated to the top, liquid can possibly accumulate into this area and this could turn into fire. In order to alleviate this risk, manufacturers attempt to review in detail the potential path of the liquid in case of failure and to modify connections accordingly, respectively provide additional covers. WO2017/165590A1 discloses the use of a such an additional cover, which need to be welded or riveted to the main heatshield, requiring a modification of the main heatshield thereby possibly weakening it.

[0006] Furthermore, these measures clearly limit packaging possibilities all the while in modern engines and machineries it is becoming more and more challenging to find the required mounting space for the aftertreatment components.

[0007] Similar problems arise with other heat-radiating components, such as a turbocharger or a braking system, encapsulated within a heat shield assembly.

Object of the invention

[0008] It is therefore an object of the present invention to provide an improved heat- radiating assembly without the above described shortcomings. This object is achieved by a heat-radiating assembly according to claim 1.

General Description of the Invention

[0009] In order to achieve the above-mentioned object, the present invention provides a heat-radiating assembly comprising a heat-radiating system (or heat- radiating component) with a housing and a heat shield assembly being arranged around the housing. The heat shield assembly comprises at least one heat shield opening through which at least one mounting bracket and/or sensor device, which is arranged on and extending outwards from the housing, extends outward of the heat shield assembly. The heat shield opening is dimensioned so that a circumferential gap is formed between the heat shield assembly and the at least one mounting bracket and/or sensor device. According to the present invention, the heat-radiating assembly further comprises a pad of a compressible heat insulating material, the pad being arranged in the heat shield opening around the at least one mounting bracket and/or sensor device so as to entirely fill the circumferential gap between the heat shield assembly and the at least one mounting bracket and/or sensor device and being hold in place by compression of the pad of compressible heat insulating material.

[0010] The pad of compressible heat insulating material according to the present invention is preferably arranged in contact with the mounting bracket or the sensor device and spans from the bracket or sensor device over the circumferential gap so as to abut against the heat shield assembly thereby entirely filling the gap of the opening.

[0011] The pad is preferably installed in a compressed state by insertion around the at least one mounting bracket and/or sensor device. Once inserted, the compressible material of the pad tends to relax toward an uncompressed state, thereby filling the circumferential gap between the heat shield assembly and the mounting bracket and/or sensor device. The pad will accordingly automatically take the desired shape which is favorable to entirely fill the circumferential gap of the opening, i.e. to provide a tight and leak-free connection between the pad of compressible heat insulating material and the heat shield assembly. In other words, the pad may simply be inserted in the heat shield opening, thereby eliminating the need to attach the pad with additional means such as glue, crimping, riveting, screwing or welding, and the need for a flat surface of the heat shield assembly in the vicinity of the opening to attach the pad thereto.

[0012] The pad thus effectively covers the opening of the heat shield assembly and prevents any liquid to come into contact with the hot surfaces of the underlying housing. Due to the fact that the material of the pad is compressible, the pad works significantly better for filling and thereby covering the respective opening in the heat shield assembly than e.g. a thin steel sheet, i.e. the material from which the direct encapsulation is made. Any liquid falling from the engine or machinery onto the heat radiating assembly in the area of the mounting bracket or sensor device is received by the pad of compressible heat insulating material and deflected by the compressible material towards areas with lower temperatures and thus lower risk of flaming.

[0013] In other words, the present invention works as an additional part to the heat protection shield and solve disadvantages and risks due to the openings, such as formation of hot spots, heat escape and tightness of connection.

[0014] In this context it will be noted that a heat-radiating system, or heat-radiating component, is a component of an engine or a machinery which heat up to temperatures up to 1650°C. The rise of temperature is due to the operation of the engine or machinery and may be of various origin. In embodiments, the heat- radiating system heats up due the passage of combustion gases (such as e.g. for an exhaust gas treatment system or a catalytic converter) or by internal friction (such as e.g. for a turbocharger or a braking system). In other words, the heat radiating system may be any system radiating heat such as an exhaust gas treatment system, a turbocharger, a catalytic converter or a braking system. When the heat-radiating system is an exhaust gas treatment system, the system usually has a generally tubular form and the pad of compressible material arranged to entirely fill an opening on the top of the tubular form will deflect the liquid in circumferential direction towards the side of the assembly.

[0015] In some embodiments, two or more mounting brackets and/or sensor devices may be arranged through the heat shield opening, and the pad of compressible heat insulating material is conformed as one single piece configured to fill up the gap between the two or more mounting brackets and/or sensor devices and the heat shield assembly.

[0016] According to the same or other embodiments, the heat shield assembly may comprise a plurality of heat shield openings through which mounting brackets and/or sensor devices are arranged and each one of the openings may be filled with a pad of compressible heat insulating material.

[0017] Compared to conventional heat shield assembly and heat radiating system, the present heat radiating assembly presents the following advantages: - quick and easy installation of the pad of compressible heat insulating material on the heat radiating system such as e.g. a catalytic converter, a turbocharger or a braking system; no need for complex assembly tools such as rivets, screws, welding equipment... - ease of implementation of the pad, in a wide variety of shapes and sizes; - robustness against thermal and mechanical constraints, high flexibility of the pad; - no additional weight or constraint on the heat shield assembly.

[0018] Any kind of compressible heat insulating material may be used for the pad of the present invention. However, in embodiments, the pad of compressible heat insulating material has a density comprised between 350 and 4300 g/m?, preferably between 500 and 4200 g/m°.

[0019] According to the same or other embodiments, the pad of compressible heat insulating material has a thickness which is typically similar to a thickness of the heat shield assembly. In preferred embodiments, the pad of compressible heat insulating material has a thickness comprised between 2 and 30 mm, preferably between 3 and 25 mm. In embodiments, the pad might be slightly thicker than the heat shield assembly, thereby deflecting any liquid onto the heat radiating assembly towards areas further away from the mounting bracket and/or sensor device with lower temperatures and thus lower risk of flaming.

[0020] In order to enhance the tight-fit connection between the pad of compressible heat insulating material and the heat shield assembly, a width and/or a length of the pad of compressible heat insulating material is at least 1% greater, preferably at least 5% greater, than a respective width and/or length of the heat shield opening enclosing the pad. In other words, the pad is preferably bigger (e.g. larger and/or wider) than the circumferential gap between the heat shield assembly and the at least one mounting bracket and/or sensor device. The pad will accordingly always be held in a compressed state while in place in the heat shield opening thereby ensuring a tight and leak-proof connection between pad and heat shield assembly.

[0021] In order to enhance its resistance and lifetime, the pad of compressible heat insulating material is preferably covered with a thin protective layer having a thickness comprised between 0.01 and 0.25 mm. The skilled person will appreciate that any kind of heat-resisting material may be used for the thin protective layer. In preferred embodiments, the thin protective layer is made of stainless steel or aluminum, or wherein the thin protective layer comprises a textile material or a silicon material. The thin protective layer may enhance the impermeability of the pad of compressible heat insulating material. At the same time the thin protective layer may act as a heat reflector which reduces the temperature of the contact surface.

[0022] Advantageously, the pad of compressible heat insulating material covered with the thin protective layer may be resistant to temperatures up to 1500 °C, preferably up to 1650 °C. The skilled person will be well aware of suitable compressible materials which can resist such high temperatures. Suitable materials which are preferred are glass and refractory material, so that the pad of compressible heat insulating material preferably comprises glass fibers, fiberglass (or textile glass fiber), polycrystalline mullite fibers, polycrystalline wool, refractory ceramic fibers, low bio-persistent fibers, microporous silica or glass pellets.

Brief Description of the Drawings

[0023] Further details and advantages of the present invention will be apparent from the following detailed description of not limiting embodiments with reference to the attached drawing, wherein:

Fig. 1 is a cross-sectional view of a portion of a heat radiating assembly;

Fig. 2a is a detail view of the heat radiating assembly of Fig 1 with an installed pad of compressible heat insulating material,

Fig. 2b is a perspective view of the pad of Fig. 2a;

Fig. 3a is a detail view of an alternative heat radiating assembly with an installed pad of compressible heat insulating material; and

Fig. 3b is a perspective view of the pad of Fig. 3b.

Description of Preferred Embodiments

[0024] Fig. 1 shows a cross-sectional view of a portion of a heat radiating assembly wherein the heat radiating system 11 is an exhaust treatment system 11. The exhaust treatment system 11 typically comprises one or more exhaust gas treatment components 140 such as one or more catalytic converters and/or fuel particulate filters which are arranged within a common housing 12. A heat shield assembly 14 is arranged around the housing 12 in order to reduce the skin temperature of the heat radiating assembly 10. The heat radiating assembly 10 may have any desired form, however an exhaust treatment system 11 usually has a generally tubular form and is provided with end cones 160 having a connection port 180 for connecting the exhaust treatment system 11 to exhaust gas pipes 200.

[0025] The heat shield assembly 14 comprises at least one heat shield opening 16 through which at least one mounting bracket 18 arranged on the housing 12 extends outward of the heat shield assembly 14. In order to allow for a proper installation of the heat shield encapsulation 14 and due to process tolerances, the heat shield opening 16 is larger than the corresponding cross section of the mounting bracket 18, so that a circumferential gap 20 is formed between said heat shield assembly 14 and the mounting bracket 18. Due to this gap, the opening 16 lets some small surfaces 22 of the housing 12 exposed to liquid.

[0026] In order to shield the exposed surfaces from liquids from the engine, the heat radiating assembly 10 of Fig. 2 further comprises a pad 24 of a compressible heat insulating material that is arranged around the mounting bracket 18 and extends outwards from the mounting bracket so as to entirely fill the circumferential gap between the heat shield assembly 14 and the mounting bracket 18.

[0027] The pad 24 of a compressible heat insulating material is preferably a pad made of fibers, such as glass fibers, fiberglass (or textile glass fibers), polycrystalline mullite fibers, polycrystalline wool, refractory ceramic fibers, low bio-persistent fibers, or microporous silica or glass pellets. The pad material is preferably dense so as to be impermeable for the liquids to be faced. In order to enhance the resistance, lifetime and impermeability of the compressible material, the material may be covered with a thin protective layer 28, e.g. an aluminum foil or a stainless- steel foil having a thickness of less than 250 um. The thin protective layer enhances the impermeability of the compressible material without unduly reducing the compressibility and flexibility of the material. At the same time the thin protective layer may act as a heat reflector which reduces the temperature of the contact surface.

[0028] The pad 24 of compressible heat insulating material is preferably arranged in contact with the mounting bracket 18 and spans from the bracket 18 over the circumferential gap so as to abut against the heat shield assembly 14 thereby entirely filling the gap of the opening. The pad 24 may be easily installed on the heat radiating assembly 10 by sliding the pad 24 in the circumferential gap onto the bracket 18. For this, the pad 24 is preferably provided with an opening 26 (Fig. 2b), so that the pad 24 glides around and remains in contact with the outer circumference of the bracket 18.

[0029] The pad 24 is preferably installed, i.e. inserted, in a compressed state around the mounting bracket 18. Once inserted, the compressible material of the pad 24 tends to relax toward an uncompressed state, thereby filling the circumferential gap between the heat shield assembly 14 and the mounting bracket 18. The pad will accordingly automatically take the desired shape which is favorable to entirely fill the circumferential gap of the opening, i.e. to provide a tight and leak- free connection between the pad of compressible heat insulating material and the heat shield assembly (Fig. 2a). In other words, the pad may simply be inserted in the heat shield opening, thereby eliminating the need to attach the pad with additional means such as glue, crimping, riveting, screwing or welding.

[0030] n alternative embodiments, such as the embodiment of Fig. 3, the heat shield assembly 14 comprises at least one heat shield opening 16 through which two sensor ports 30, 32 on which additional components such as e.g. sensors may be mounted, are arranged on the housing 12 extending outward of the heat shield assembly 14. In order to allow for a proper installation of the heat shield encapsulation 14 and due to process tolerances and the spatial closeness of the two sensor ports 30, 32, the heat shield opening 16 is larger than the corresponding cross section of the two sensor ports, so that a circumferential gap is formed between the heat shield assembly 14 and the sensor ports.

[0031] In order to shield the exposed surfaces from liquids, the heat radiating assembly of Fig. 3 further comprises a pad 24’ of compressible heat insulating material, covered with a thin protective layer 28’. The pad 24’ is conformed as one single piece configured to fill up the gap between the two sensor ports 30, 32 and the heat shield assembly 14.

[0032] The pad 24’ may be easily installed on the heat radiating assembly 10 by sliding the pad 24’ in the circumferential gap onto the sensor ports 30, 32. For this the pad 24 is preferably provided with two openings 26’ (Fig. 3b), so that the pad 24’ glides around and remains in contact with the outer circumference of the sensor ports 30, 32.

List of Reference Symbols heat radiating assembly 11 exhaust treatment system 12 housing 14 heat shield assembly 16 heat shield opening 18 mounting bracket circumferential gap 22 surfaces 24, 24’ pad of a compressible heat insulating material 26, 26’ opening 28, 28’ thin protective layer 30, 32 sensor ports 140 exhaust gas treatment components 160 end cones 180 connection port 200 exhaust gas pipes

Claims

1. Heat-radiating assembly comprising a heat-radiating system with a housing and a heat shield assembly being arranged around said housing, said heat shield assembly comprising at least one heat shield opening through which at least one mounting bracket and/or sensor device, which is arranged on and extending outwards from said housing, extends outward of said heat shield assembly; wherein said heat shield opening is dimensioned so that a circumferential gap is formed between said heat shield assembly and the at least one mounting bracket and/or sensor device; characterized by a pad of a compressible heat insulating material, said pad being arranged in said heat shield opening around said at least one mounting bracket and/or sensor device so as to entirely fill the circumferential gap between said heat shield assembly and the at least one mounting bracket and/or sensor device and being hold in place by compression of said pad of compressible heat insulating material.

2. Heat-radiating assembly according to claim 1, wherein said pad of compressible heat insulating material has a density comprised between 350 and 4300 g/m? preferably between 500 and 4200 g/m°.

3. Heat-radiating assembly according to any one of the preceding claims, wherein said pad of compressible heat insulating material has a thickness comprised between 2 and 30 mm, preferably between 3 and 25 mm.

4. Heat-radiating assembly according to claim 1, wherein said pad of compressible heat insulating material comprises glass or refractory material, preferably the pad comprises glass fibers, fiberglass, polycrystalline mullite fibers, polycrystalline wool, refractory ceramic fibers, low bio-persistent fibers, microporous silica and/or glass pellets.

5. Heat-radiating assembly according to any one of the preceding claims, wherein a width and/or a length of the pad of compressible heat insulating material is at least 1% greater, preferably at least 5% greater, than a respective width and/or length of the heat shield opening enclosing said pad.

6. Heat-radiating assembly according to any one of the preceding claims, wherein said pad of compressible heat insulating material is covered with a thin protective layer having a thickness comprised between 0.01 and 0.25 mm.

7. Heat-radiating assembly according to claim 6, wherein said thin protective layer is made of stainless steel or aluminum, or wherein said thin protective layer comprises a textile material or a silicon material.

8. Heat-radiating assembly according to claim 6 or 7, wherein said pad of compressible heat insulating material covered with the thin protective layer is resistant to temperatures up to 1500 °C, preferably up to 1650 °C.

9. Heat-radiating assembly according to any one of the preceding claims, wherein the heat-radiating system is an exhaust gas treatment system, a catalytic converter, a turbocharger or a braking system.