Aerosol generating device with insulator
By using the electrical contact between the heat insulator and the housing in the aerosol generation device to reduce the heat conduction path, the problem of heat failure to effectively transfer to the aerosol-forming matrix is solved, the device efficiency is improved and component damage and user discomfort is reduced.
Patent Information
- Application Number
- CN202380083663.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-12-06
- Filing Date
- 2023-12-04
- Publication Date
- 2025-07-04
AI Technical Summary
In existing aerosol generation devices, heat cannot be effectively transferred to the aerosol-forming matrix, resulting in inefficiency of the device and may damage the components and discomfort when the user holds it.
The heat insulator and the housing are mechanically connected by electrical contacts to reduce the heat conduction path, and the interior and exterior walls are isolated using vacuum or other thermal insulation materials to ensure that heat is mainly transferred to the aerosol-forming matrix.
The efficiency of the heater is improved, the heat is reduced by the housing and other components, the overall efficiency of the device and the discomfort of the user when holding it.
Smart Images
Figure CN120265162A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an aerosol generating device, and more particularly to an aerosol generating device having a heat insulator such as a vacuum heat insulator. Background Art
[0002] As an alternative to traditional tobacco products such as cigarettes, cigars, cigarillos, and roll-your-own cigarettes, the popularity and use of aerosol generating devices and systems (also referred to as vaporizers) have grown rapidly in the past few years. Different from burning tobacco in traditional tobacco products, various devices and systems can be used to heat or warm aerosolizable substances, which may or may not include nicotine or other active substances.
[0003] A commonly used type of aerosol generating system is the heated substrate type of aerosol generation or heat-not-burn type. This type of system generates an aerosol or vapor by heating a consumable article (i.e., a "heat-not-burn stick") containing an aerosol-forming substrate such as reconstituted tobacco to a temperature typically in the range of 150°C to 350°C. Heating the aerosol-forming substrate without burning or igniting it releases an aerosol that includes the components desired by the user but does not include undesired combustion by-products. In addition, the aerosol typically generated by heating tobacco or other aerosolizable materials does not include unpleasant burnt or bitter tastes that may be produced by combustion.
[0004] Typically, a heat-not-burn consumable article such as a stick is inserted into a cavity of a heat-not-burn device, and one end of the stick protrudes from the device and forms an inhalation mouthpiece. A heater in the heat-not-burn device then supplies heat to the stick to aerosolize the aerosolizable material in the aerosol-forming substrate contained in the stick, and the generated aerosol is provided to the user from the protruding end of the stick.
[0005] Typically, not all of the heat generated by the heater is transferred to the consumable article to generate an aerosol. This reduces the overall efficiency of the device and shortens the battery life. In addition, these losses may cause other components in the device to be heated, which may lead to damage and discomfort to the user when the user holds the device.
[0006] The object of the present invention is to solve these problems. Summary of the Invention
[0007] According to one aspect of the present invention, there is provided an aerosol generating device, the aerosol generating device comprising: a heat insulator, the heat insulator comprising: an inner wall and an outer wall separated from each other; a cavity defined in the inner wall, an aerosol-forming substrate being receivable in the cavity; and a heater positioned to heat the aerosol-forming substrate when the aerosol-forming substrate is received in the cavity; a housing surrounding the heat insulator; and electrical contacts connected to the heater, wherein at least one of the electrical contacts is mechanically connectable to the housing to hold the heat insulator in place.
[0008] Advantageously, since the electrical contacts also provide a mechanical connection between the heat insulator and the housing, the number of heat conduction paths between the heat insulator and the housing is reduced. By reducing the amount of heat conducted from the heat insulator to the housing, the efficiency of the heater can be increased, since a greater proportion of the heat can be transferred to the aerosol-forming substrate. In addition, the housing is less heated, which can reduce damage to other components of the device located in the housing and may be desirable from the perspective of a user holding the housing.
[0009] The heat insulator and the heater may be collectively referred to as a heating device. The heating device may be received in a chamber of the housing (such as a chamber defined by a side portion of the housing extending from a base portion of the housing). The heating device may be received in the chamber such that an air gap is provided between the outer wall of the heat insulator and the housing. The region between the inner wall and the outer wall of the heat insulator may be referred to as a heat-insulating region.
[0010] Preferably, the electrical contacts provide the only connection between the heat insulator and the housing. Advantageously, this reduces the heat transferred between the heat insulator and the housing by minimizing the number of heat conduction paths between the heat insulator and the housing. In other words, preferably, the only way heat can be transferred between the heat insulator and the housing is through the electrical contacts.
[0011] Preferably, the inner wall and the outer wall of the heat insulator are separated from each other by a vacuum, thereby providing a vacuum heat insulator. In this way, heat conduction and / or convection between the inner wall and the outer wall of the heat insulator is further inhibited, thereby further reducing heat transfer from the heat insulator to the housing. Alternatively, the inner wall and the outer wall of the heat insulator may be separated from each other by an air gap, an aerogel, a foamed material, a fibrous material, and / or any combination of the above materials.
[0012] Preferably, the heat insulator is removable from the housing. In other words, at least one of the electrical contacts can be disconnected from the housing mechanically. For example, the heating device providing the heat insulator and the heater can be removed from the housing (such as from the chamber). In this way, the heat insulator can be replaced, cleaned, and / or repaired. Alternatively, the heat insulator can be permanently fixed in the housing, which can make the connection between the heat insulator and the housing more secure.
[0013] The cavity may include at least one opening at which an inner wall and an outer wall are joined, and one or more electrical contacts may be positioned at a location on the insulator that minimizes heat flow between the at least one opening and the electrical contacts. In this way, the electrical contacts are made on the part of the outer wall that remains coldest during use of the aerosol-generating device. This reduces heat transfer between the insulator and the housing. For example, the electrical contacts may be positioned at a location that maximizes the shortest distance between the at least one opening and the electrical contacts. In other words, in the case where there are multiple openings in the cavity, the electrical contacts are not placed in the vicinity of any of these openings. The distance may be determined along a direct path between the opening and the electrical contacts. Preferably, the distance is determined along the thermal path between the opening and the electrical contacts; since heat flow is inhibited by the insulating portion of the insulator, the distance may be measured along the thermal path through the air surrounding the insulator and / or along the outer wall of the insulator.
[0014] The insulator may be cup-shaped such that the cavity has a single opening at which the inner wall and the outer wall are joined, and wherein the electrical contacts are positioned at the base of the insulator opposite the opening of the cavity. In other words, the insulator may be attached to the housing in a cantilever arrangement, where only one end of the insulator is connected to the housing. By positioning the electrical contacts at the base of the insulator, the electrical contacts are made on the part of the outer wall that remains coldest during use, thereby reducing heat transfer from the insulator to the housing. In other words, the distance between the electrical contacts and the opening of the cavity is maximized.
[0015] Alternatively, the insulator may be tubular such that the cavity has two openings at which the inner wall and the outer wall are joined, and wherein the electrical contacts are positioned on a side of the insulator spaced apart from the two openings of the cavity. The electrical contacts may be arranged equidistant from the two openings of the cavity, thereby maximizing the shortest distance to the two openings. Alternatively, if one of the openings is determined to generate more heat than the other opening, the position of the electrical contacts may be moved further away from that opening. In this way, the electrical contacts are made on the part of the outer wall that remains coldest during use, thereby reducing heat transfer from the insulator to the housing.
[0016] The electrical contacts may be mechanically connected to the base portion of the housing. By connecting the electrical contacts to the base portion of the housing, the heat transferred to the side portion of the aerosol-generating device (which may be held by the user) is reduced. Alternatively, the electrical contacts may be mechanically connected to the side portion of the housing. The side portion of the housing may include an inner wall and an outer wall, and the electrical contacts may be mechanically connected to the inner wall. Insulating material may be located between the inner wall and the outer wall, thereby further reducing heat transfer from the insulator to the housing.
[0017] The electrical contact member may include a pair of pins. The pair of pins may be connected to the housing by a lockable coupling. The pair of pins may be connected to the housing using a snap connection or a thread.
[0018] The electrical contact member may include a pin and a threaded outer surface that may engage with the housing to hold the heat insulator in place.
[0019] Those skilled in the art will understand that any device or apparatus feature described herein may be provided as a method feature. It should be understood that the specific combinations of the various features described and defined in any aspect herein may be implemented and / or provided and / or used independently. In addition, it should be understood that the present invention is described herein by way of example only, and details may be modified within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] One or more embodiments will now be described by way of example only with reference to the drawings, in which:
[0021] Figure 1A A schematic cross-section of a first embodiment of an aerosol-generating device including a heating device is shown;
[0022] Figure 1B shows Figure 1A a cross-section of the heating device of the embodiment shown;
[0023] Figure 2A A schematic cross-section of a second embodiment of an aerosol-generating device including a heating device is shown;
[0024] Figure 2B shows Figure 2A a cross-section of the heating device of the embodiment shown; and
[0025] Figure 3 and Figure 4 shows an alternative heating device that may be used in embodiments of the aerosol-generating device. DETAILED DESCRIPTION
[0026] In the following description and drawings, corresponding features may preferably be identified using corresponding reference numerals to avoid the need to describe in detail the same features for each embodiment.
[0027] Figure 1A An exemplary cross-section of a first embodiment of an aerosol-generating device 1 is depicted. The device 1 has a housing 10 that has a base portion 12 and a side portion 14. More specifically, the side portion 14 extends from the base portion 12 to define a chamber 15. In this embodiment, the side portion 14 includes an outer wall 14a and an inner wall 14b, but it should be understood that the side portion 14 may also include only a single wall.
[0028] Apparatus 1 includes a heating device 100, which is held within a housing 10 (such as within a chamber 15). In this way, the housing 10 surrounds the heating device 100. Figure 1B The cross-section of [description missing] shows further details of the heating device 100. The heating device 100 includes a thermal insulator 102. The thermal insulator 102 includes an inner wall 104 and an outer wall 106, which are spaced apart from each other such that the space therebetween encloses a thermal insulation region 108. Preferably, the thermal insulation region 108 includes a vacuum, thereby providing a vacuum thermal insulator 102. Alternatively or additionally, the thermal insulation region 108 may include an air gap, aerogel, foamed material, fibrous material, and / or any combination of the above materials.
[0029] The heating device 100 includes a cavity 110, which is disposed adjacent to the inner wall 104 and is configured to receive an aerosol-forming substrate. For example, a consumable 5 may be inserted into the cavity 110, where the consumable 5 contains an aerosol-forming substrate such as tobacco 6. The consumable 5 is typically an elongate rod or stick, which a user may insert into the cavity 110 via an opening 111 of the cavity 110. The thermal insulator 102 has a generally cylindrical shape, such that the thermal insulator 102 can completely surround the consumable 5 to maximize the thermal insulation efficiency. In this example, the thermal insulator 102 includes an opening 111 for receiving the consumable 5 at one longitudinal end and being closed at the opposite end. Thus, when viewed perpendicular to the longitudinal axis of the opening, the thermal insulator 102 has a cup-shaped cross-section. In other words, the cavity 110 has a single opening 111 at which the inner wall 104 and the outer wall 106 join.
[0030] A heater 112 is disposed within the thermal insulation region 108, on the inner wall 104. The heater 112 is configured to heat the inner wall 104 by conduction, such that the inner wall 104 heats the consumable 5 and the air within the cavity 110 by conduction and radiation. The heater 112 is powered by a power source (such as a battery) located within a base portion 12 of the housing 10 of the apparatus 1, which is not shown.
[0031] By disposing the heat insulator 102 in the heating device 100, the amount of wasted heat is reduced because the heat insulating region 108 inhibits heat from directly conducting or convecting from the heater 112 to the outer wall 106. Nevertheless, during use of the device 1, the outer wall 106 may get hot, for example due to convection of air from the opening 111 of the cavity 110 or due to conduction occurring at the opening 111 between the inner wall 104 and the outer wall 106. By disposing the heating device 100 in the chamber 15 of the device 1, an air gap is provided between the outer wall 106 of the heating device 100 and the housing 10 of the device 1. Advantageously, this can reduce the heating of the housing 10, thereby improving the efficiency of the device 1 and preventing discomfort to a user holding the housing 10 of the device 1.
[0032] The heating device 100 includes one or more electrical contacts 116 (e.g., via a first wire connector 114a and a second wire connector 114b) connected to the heater 112. The electrical contacts 116 can be mechanically connected to the housing 10 of the device 1. In this embodiment, the electrical contacts 116 can be mechanically connected to the base portion 12 of the housing 10. By using the same device between the heat insulator 102 and the housing 10 to provide both a mechanical connection and an electrical connection simultaneously, the number of heat conduction paths is reduced. Advantageously, this can further reduce the heating of the housing 10, thereby improving the efficiency of the device 1 and preventing discomfort to a user holding the housing 10 of the device 1.
[0033] Preferably, the electrical contacts 116 provide the only connection between the heat insulator 102 and the housing 10. In this way, the number of heat conduction paths is minimized, thereby further reducing the heat transfer between the heat insulator 102 and the housing 10. To achieve this, the material and shape of the electrical contacts 116 are selected to provide sufficient strength to hold the heating device 100 in place within the chamber 15 during use of the device 1, without the need for additional contact points between the heating device 100 and the housing 10. In other words, the electrical contacts 116 provide a rigid connection, whereby movement of the heat insulator 102 relative to the housing 10 is inhibited.
[0034] Preferably, the electrical contacts 116 can also be disconnected from the mechanical connection with the housing 10 such that the heating device 100 can be removed from the housing 10. Advantageously, by providing a heating device 100 that can be removed from the housing 10, parts of the heating device 100 can be easily repaired and / or replaced without the need to replace the entire device 1.
[0035] In this example, the electrical contacts 116 include a pair of pins. The pins can be connected to the housing 10 by a lockable coupling. The pins can be inserted into the base portion 12 via a small rotation or translation and locked in place.
[0036] In one embodiment, the connection between the pin and the base portion 12 can correspond to the connection applied between a fluorescent lamp starter and its corresponding socket. More specifically, the pin can include a flanged portion that holds the pin within an outwardly extending groove in the base portion 12, where movement of the pin (e.g., by rotating the heating device 100) through the groove allows the pin to be removed from the base portion 12 at the opening. The electrical and mechanical connection between the heating device 100 and the housing 10 can be provided in other ways. For example, the heating device 100 can be connected to the housing 10 by a bayonet connector, where a radial pin connected to the heating device 100 engages in a pair of L-shaped slots on the housing 10. Alternatively, a threaded connector can be provided, where the heating device 100 includes a threaded outer surface that can engage a corresponding thread in the base portion 12 of the housing 10. As another alternative, the electrical contact 116 can include a (single) pin and a threaded outer surface that can engage the housing 10 to hold the heat insulator 102 in place. This arrangement enables a secure mechanical connection between the heating device 100 and the housing 10 and also provides a consistent power supply to the heating device 100 via the electrical contact 116.
[0037] The electrical contact 116 is preferably located at a position on the heat insulator 102 that minimizes heat flow between the opening 111 and the electrical contact 116. In this way, the electrical contact 116 is made on the part of the outer wall 106 that remains coldest during use of the aerosol generating device 1. This reduces heat transfer between the heat insulator 102 and the housing 10. The electrical contact 116 can be located at a position on the heat insulator 102 that maximizes the distance between the electrical contact and the opening 111 of the cavity 110. This maximum distance can correspond to the direct path between the opening 111 and the electrical contact 116. Preferably, this maximum distance is determined as the maximum distance along the thermal path between the opening 111 and the electrical contact 116; since heat flow is inhibited by the heat insulating region 108 of the heat insulator 102, this distance can be measured along the thermal path through the air surrounding the heat insulator 102 and / or along the outer wall 106 of the heat insulator 102.
[0038] In Figure 1A and Figure 1BIn the cup-shaped insulator 102 shown, the electrical contact 116 can be located at the base of the insulator 102 opposite the opening 111 of the cavity 110. In other words, the insulator 102 is attached to the housing 10 in a cantilevered arrangement, where only one end of the insulator 102 is connected to the housing 10. In this way, the distance along the heat path between the opening 111 and the electrical contact 116 is maximized, thereby reducing the heat transfer between the opening and these electrical contacts. In other words, the electrical contact 116 is made on the coldest part of the outer wall 106 during use, thereby reducing the amount of heat transferred from the insulator 102 to the housing 10 of the device 1.
[0039] Figure 2A An exemplary cross-section of a second embodiment of the aerosol-generating device 1 is depicted. The device 1 is similar to the device 1 described above in that the device includes a housing 10 having a base portion 12 and a side portion 14 enclosing a chamber 15. However, the device 1 includes an alternative heating device 200 shown in more detail in Figure 2B In Figure 2B the heating device 200 is depicted as having a consumable 5 inserted therein, where the consumable 5 includes tobacco 6 and a filter 7.
[0040] Unlike Figure 1A and Figure 1B the embodiment shown, in this embodiment both longitudinal ends of the insulator 202 are open, such that the insulator has a tubular cross-section when viewed perpendicular to the longitudinal axis of the insulator. More specifically, the cavity 210 has a first opening 211a at the first longitudinal end and a second opening 211b at the second longitudinal end. The first opening 211a is configured to receive the consumable 5. A plug 236 can be provided in the second opening 211b to prevent the consumable 5 from being inserted too far into the cavity 210. The plug 236 can include PEEK, rubber, or other suitable heat-resistant materials.
[0041] The thermal insulator 202 also includes one or more electrical contacts 216 connected to the heater 212. The electrical contacts 216 can be mechanically connected to the housing 10 of the device 1. In this embodiment, the electrical contacts 216 can be mechanically connected to the side portion 14 of the housing 10. More specifically, the electrical contacts 216 can be mechanically connected to the inner wall 14b of the side portion 14 of the housing 10. It should be understood that in the case where the side portion 14 has only a single wall, the electrical contacts 216 can be mechanically connected to the single wall (e.g., the outer wall). By using the same device between the thermal insulator 202 and the housing 10 to provide both mechanical and electrical connections simultaneously, the number of heat conduction paths is reduced. Preferably, the electrical contacts 216 provide the only connection between the thermal insulator 202 and the housing 10. In this way, the number of heat conduction paths is minimized, thereby further reducing the heat transfer between the thermal insulator 202 and the housing 10. To achieve this, the material and shape of the electrical contacts 216 are selected to provide sufficient strength to hold the heating device 200 in place within the chamber 15 during use of the device 1, without the need for additional contact points between the heating device 200 and the housing 10. In other words, the electrical contacts 216 provide a rigid connection, whereby the movement of the thermal insulator 202 relative to the housing 10 is inhibited.
[0042] Preferably, the electrical contacts 216 can also be disconnected mechanically from the housing 10 such that the heating device 200 can be removed from the housing 10. Advantageously, by providing a heating device 200 that can be removed from the housing 10, the parts of the heating device 200 can be easily repaired and replaced without the need to replace the entire device 1.
[0043] In this example, the electrical contacts 216 include a pair of pins. The pins can be connected to the housing 10 by a lockable coupling. The pins can be inserted into the side portion 14 of the housing 10 via a small rotation or translation and locked in place. As previously described with respect to the heating device 100, a variety of connection arrangements can be used to provide both a secure mechanical connection and an electrical connection between the heating device 200 and the housing 10 via the electrical contacts 216.
[0044] The electrical contacts 216 are preferably located at a position on the thermal insulator 202 that minimizes the heat flow between the openings 211a, 211b and the electrical contacts 216. In this way, the electrical contacts 216 are made on the part of the outer wall 206 that remains the coldest during use of the aerosol generating device 1. This reduces the heat transfer between the thermal insulator 202 and the housing 10.
[0045] In Figure 2A and Figure 2BIn the illustrated tubular insulator 202, the electrical contact 216 may be located at a side of the insulator 202 that is spaced apart from the first opening 211a and the second opening 211b of the cavity 210. For example, the electrical contact 216 may be located at a side of the insulator 202 that is substantially equidistant from the first opening 211a and the second opening 211b of the cavity 210. At this location, the shortest distance between the electrical contact 216 and any one of the openings 211a, 211b is maximized, thereby reducing heat transfer from any one of the openings 211a, 211b to the electrical contact 216. Alternatively, if one of the openings 211a, 211b is determined to generate more heat than the other opening (e.g., due to the insulating properties of the plug 236), the position of the electrical contact 216 may be adjusted accordingly (e.g., by moving the electrical contact closer to the opening 211b having the plug 236). In other words, the electrical contact 216 is made on the portion of the outer wall 206 that is coolest during use, thereby reducing the amount of heat transferred from the insulator 202 to the housing 10 of the device 1. In any of the above-described embodiments, the coolest portion of the outer wall 206 can be calculated (such as by computer simulation) to determine the optimal placement of the electrical contact 216.
[0046] It should be understood that the electrical contacts 116 , 216 described above may be located at any position of the thermal isolator 102 , 202 to provide a mechanical connection to the housing 10 of the device 1 . Figure 3 and Figure 4 An alternative embodiment of a heating device 300, 400 that may be used in the apparatus 1 is shown. The heating device 300 is similar to the previously described cup-shaped heating device 100, but differs in that the electrical contact 316 is located at the end of the insulator 302 adjacent to the opening 311 of the cavity 310. The heating device 400 is similar to the previously described cup-shaped heating devices 100, 300, but differs in that the electrical contact 416 is located on the side of the insulator 402 adjacent to the opening 411 of the cavity 410. This may make inspection and / or servicing of the heating device 300, 400 easier and may be preferred for certain types of apparatus 1. As previously described, the electrical contacts 316, 416 may be mechanically connected to the housing 10 of the apparatus 1 and preferably provide the only connection between the insulator 302, 402 and the housing 10.
[0047] Although the above is directed to exemplary embodiments of the present invention, it should be understood that the present invention is described herein only by way of example, and modifications of detail may be made within the scope of the present invention. In addition, it will be understood by those skilled in the art that the present invention may not be limited to the embodiments disclosed herein, or to any details shown in the accompanying drawings that are not described in detail herein or defined in the claims.
[0048] In addition, by considering the specification, other and further embodiments of the present invention will be apparent to those skilled in the art and can be designed without departing from the basic scope of the present invention as determined by the appended claims.
Claims
1. An aerosol generating device, comprising: A heat insulator, the heat insulator comprising: an inner wall and an outer wall separated from each other; a cavity defined in the inner wall, an aerosol forming substrate being receivable in the cavity; and a heater positioned to heat the aerosol forming substrate when the aerosol forming substrate is received in the cavity; A housing surrounding the heat insulator; and Electrical contacts connected to the heater, wherein at least one of the electrical contacts is capable of being mechanically connected to the housing to hold the heat insulator in place.
2. The aerosol generating device according to claim 1, wherein, The electrical contacts provide the only connection between the heat insulator and the housing.
3. The aerosol generating device according to claim 1 or claim 2, wherein, The inner wall and the outer wall of the heat insulator are separated from each other by a vacuum, thereby providing a vacuum heat insulator.
4. The aerosol generating device according to any one of the preceding claims, wherein, The heat insulator is removable from the housing.
5. The aerosol generating device according to any one of the preceding claims, wherein, The cavity includes at least one opening at which the inner wall engages the outer wall, and the one or more electrical contacts are positioned at a location on the heat insulator that minimizes heat flow between the at least one opening and the electrical contacts.
6. The aerosol generating device according to claim 5, wherein, The heat insulator is cup-shaped such that the cavity has a single opening at which the inner wall engages the outer wall, and wherein the electrical contacts are positioned at a base of the heat insulator opposite the opening of the cavity.
7. The aerosol generating device according to claim 5, wherein, The heat insulator is tubular such that the cavity has two openings at which the inner wall engages the outer wall, and wherein the electrical contacts are positioned on a side of the heat insulator spaced apart from the two openings of the cavity.
8. The aerosol generating device according to any one of the preceding claims, wherein, The electrical contacts are capable of being mechanically connected to a base portion of the housing.
9. The aerosol generating device according to any one of claims 1 to 7, wherein, The electrical contacts are capable of being mechanically connected to a side portion of the housing.
10. The aerosol generating device according to claim 9, wherein, The side portion of the housing includes an inner wall and an outer wall, and the electrical contacts are capable of being mechanically connected to the inner wall.
11. The aerosol generating device according to any one of the preceding claims, wherein, The electrical contacts include a pair of pins.
12. The aerosol generating device according to claim 11, wherein, The pair of pins is capable of being connected to the housing by a lockable coupling.
13. The aerosol generating device according to claim 12, wherein, The pair of pins is capable of being connected to the housing using a snap connection or a thread.
14. The aerosol generating device according to any one of claims 1 to 10, wherein, The electrical contacts include a pin and a threaded outer surface that is capable of engaging the housing to hold the heat insulator in place.