High-efficiency heat dissipation pressure sensor

Abstract

The invention specifically relates to an efficient heat dissipation pressure sensor, and the main conception of the invention lies in that a heat dissipation channel formed by encircling a cylindrical shell, a metal wall shell and a pressure joint carries out the heat dissipation of a pressure measurement assembly in a mounting cavity, thereby improving the heat dissipation contact area of the pressure measurement assembly. And the heat dissipation efficiency is further improved. It is worthy of understanding that the pressure introduction channel is used for allowing a medium to enter and allowing the pressure sensitive element to carry out pressure detection. And the medium inlet channel and the medium outlet channel are respectively used for introducing a medium into the heat dissipation channel and carrying out heat dissipation on the pressure measurement assembly, and the medium after heat exchange is discharged from the heat dissipation channel through the medium outlet channel, so that circulation of the medium in the heat dissipation channel is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure sensors, and in particular to a pressure sensor with high-efficiency heat dissipation. Background Art

[0002] With the continuous development of semiconductor technology, micro sensors and micro sensor chips are becoming more and more popular. As one of the common sensor types, pressure sensors are widely used in automotive electronics, medical electronics, smart electrical, industrial precision equipment and other scenarios. As the size of sensors continues to decrease, heat dissipation efficiency and heat dissipation stability are crucial.

[0003] In the prior art, the heat dissipation of pressure sensors is mostly achieved through heat exchange technology, such as air cooling technology, water cooling technology, oil cooling technology, etc. Without exception, these heat exchange technologies all need to be implemented through heat exchange media and heat exchange pipes. In the implementation of the prior art, if the heat dissipation efficiency is improved, it is very important to ensure the heat dissipation stability. There are often technical problems such as the heat dissipation contact area cannot be set too large, or the heat dissipation area is too large to cause fluid impact. Summary of the invention

[0004] The present invention aims to solve the technical problems in the prior art of pressure sensor heat dissipation such as low heat dissipation efficiency or excessive fluid impact during heat dissipation, and provides a pressure sensor with high heat dissipation efficiency, stable structure and small size.

[0005] The present invention provides a pressure sensor with high efficiency heat dissipation, the pressure sensor comprising:

[0006] A housing with an installation cavity comprises a main housing and a pressure joint with a pressure introduction channel formed therein; an outer end of the pressure joint is sealed and connected to the interior of a pipeline for conveying a flowing pressure medium to be measured, and an inner end is connected to the installation cavity; a medium inlet channel and a medium outlet channel are formed inside the material of the pressure joint;

[0007] A pressure measuring assembly disposed in the installation cavity, comprising a pressure sensitive element sealed at one inner end of the pressure introduction channel to measure the pressure of the fluid medium;

[0008] and a metal cylinder shell with one end sealed and fixed to the pressure joint, a heat dissipation channel is formed between the cylinder shell, the main shell and the pressure joint, two ends of the heat dissipation channel are respectively connected to the medium inlet channel and the medium outlet channel, an end of the medium inlet channel away from the heat dissipation channel is connected to the interior of the pipeline on the upstream side, and an end of the medium outlet channel away from the heat dissipation channel is connected to the interior of the pipeline on the downstream side.

[0009] Specifically, one of the main concepts of the present invention is to dissipate heat from the pressure measuring component in the installation cavity through the heat dissipation channel formed by the cylindrical shell, the metal wall shell and the pressure joint, thereby increasing the heat dissipation contact area of ​​the pressure measuring component and further improving the heat dissipation efficiency. It is worth understanding that the pressure introduction channel is used for medium entry and for the pressure sensitive element to perform pressure detection. The medium entry channel and the medium discharge channel are respectively used to introduce the medium into the heat dissipation channel to dissipate heat from the pressure measuring component, and the medium after heat exchange is discharged from the heat dissipation channel through the medium discharge channel, thereby realizing the circulation of the medium in the heat dissipation channel.

[0010] Furthermore, the pressure joint includes a tube body and a seat body located outside the pipeline; an outer end of the tube body extends into the interior of the pipeline and inwardly passes over the inner wall of the pipeline, and an inner end thereof is connected to the seat body; an end of the seat body away from the pipeline is sealingly connected to the metal cylinder shell.

[0011] Furthermore, a medium inlet is provided on the outer wall of the outer end of the tube body facing the upstream side of the pipeline, and the medium inlet is connected to the end of the medium inlet channel away from the heat dissipation channel; a medium outlet is provided on the outer wall of the outer end of the tube body facing the downstream side of the pipeline, and the medium outlet is connected to the end of the medium discharge channel away from the heat dissipation channel.

[0012] Furthermore, the medium inlet channel and the medium outlet channel each include a first partial channel arranged along the extension direction of the tube body and a second partial channel arranged inside the seat body.

[0013] In some embodiments, the heat dissipation channel includes a double-line spiral channel surrounded by the outer side wall of the main shell facing the pipe and the inner side wall of the cylinder shell, and the double-line spiral channel includes a first spiral channel and a second spiral channel arranged side by side; the first spiral channel and the second spiral channel are connected at one end away from the tube body, the end of the first spiral channel close to the tube body is connected to the medium inlet channel, and the end of the second spiral channel close to the tube body is connected to the medium discharge channel.

[0014] Specifically, another main concept of the present invention is to construct the heat dissipation channel into a double-line spiral shape so that the first spiral channel and the second spiral channel are arranged side by side, thereby improving the uniformity of the heat dissipation channel.

[0015] Furthermore, a double-helical groove is provided on the outer side wall of one end of the main shell body facing the pipeline, and the double-helical groove and the inner wall of the cylinder shell form the double-helical channel.

[0016] Optionally, one end of the double-line spiral groove close to the tube body is connected to the end surface of the main shell facing the pipeline through a connecting groove extending toward one side of the seat body, and the connecting groove is connected to the upper end of the corresponding medium inlet channel or medium discharge channel.

[0017] In some embodiments, the cylinder shell is punched and stretched inward to form a stretching portion, the stretching portion forms a double-line spiral groove, and a double-line spiral channel corresponding to the double-line spiral groove is formed between the stretching portion and the outer side wall of the main shell at one end facing the pipeline.

[0018] Optionally, one end of the cartridge shell facing the pipeline is integrally molded with the pressure interface.

[0019] Optionally, one end of the cylindrical shell away from the pipeline is rolled inward to form a circle of pressing edge, and the pressing edge is pressed downward and sealingly against a step surface formed on the main shell.

[0020] In summary, the present invention provides a pressure sensor with efficient heat dissipation, which has at least the following advantages:

[0021] 1. The present invention dissipates heat from the pressure measuring component in the installation cavity through the heat dissipation channel formed by the cylindrical shell, the metal wall shell and the pressure joint, thereby increasing the heat dissipation contact area of ​​the pressure measuring component and further improving the heat dissipation efficiency. It is easy to understand that the pressure introduction channel is used for medium entry and for the pressure sensitive element to perform pressure detection. The medium entry channel and the medium discharge channel are respectively used to introduce the medium into the heat dissipation channel to dissipate heat from the pressure measuring component, and the medium after heat exchange is discharged from the heat dissipation channel through the medium discharge channel, thereby realizing the circulation of the medium in the heat dissipation channel;

[0022] 2. The present invention sets the orientation of the medium inlet and the medium outlet so that the inlet and outlet face the flow direction of the medium, and the pressure medium to be measured flows into the heat dissipation channel, thereby improving the heat exchange efficiency of the heat dissipation channel;

[0023] 3. The present invention constructs the heat dissipation channel into a double-line spiral shape so that the first spiral channel and the second spiral channel are arranged side by side, thereby improving the uniformity of the heat dissipation channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments, but those skilled in the art will appreciate that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be used as a limitation on the scope of the present invention. In addition, unless otherwise specified, the drawings are only schematically representing the composition or structure of the described objects and may contain exaggerated displays, and the drawings are not necessarily drawn to scale.

[0025] Figure 1 A schematic structural diagram of a pressure sensor with high heat dissipation provided by an embodiment of the present invention;

[0026] Figure 2 A schematic structural diagram of a double-line spiral groove of a main housing provided by an embodiment of the present invention;

[0027] 1. Shell; 2. Pressure measurement component; 3. Pipe; 11. Installation cavity; 12. Main shell; 13. Pressure joint; 14. Cylinder shell; 15. Heat dissipation channel; 21. Pressure sensitive element; 22. Processing element; 23. Pin; 121. Step surface; 131. Pressure introduction channel; 132. Medium inlet channel; 133. Medium discharge channel; 134. Tube body; 135. Seat body; 141. Pressing edge; 142. Arched portion; 151. Double-line spiral channel; 132a. First part of the channel; 132b. Second part of the channel; 133a. First part of the channel; 133b. Second part of the channel; 134a. Medium inlet; 134b. Medium outlet; 135a. Installation groove; 151a. First spiral channel; 151b. Second spiral channel; 151c. Connecting groove. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1 and 2 , the present invention is described in detail.

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] It is worth noting that the embodiments of the present invention use ordinal numbers such as "first" and "second" to distinguish multiple objects, and are not used to limit the order, timing, priority or importance of multiple objects. Exemplarily, "first partial channel (132a, 133a)" and "second partial channel (132b, 133b)" are only for the convenience of description, and do not represent the difference in order, importance, etc. between the "first partial channel (132a, 133a)" and the "second partial channel (132b, 133b)". In addition, the term "connection" should be understood in a broad sense, for example, "connection" can be a fixed connection, a detachable connection, a conflicting connection or an integrated connection; wherein, "connection" can also be a direct connection or an indirect connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] The main idea of ​​the present invention is to use the inherent shell 1 component of the pressure sensor to form its heat dissipation channel 15, thereby increasing the heat dissipation contact area, and further achieving the purpose of improving the heat dissipation efficiency. At the same time, the present invention also designs the structure of the heat dissipation channel 15 to increase the flow speed of the medium therein, and on the basis of further improving the heat dissipation efficiency, it can also effectively reduce the impact of the medium on the heat dissipation channel 15, so that the structural reliability is enhanced.

[0032] For an analysis of the main concept of the present invention, see Figure 1 FIG. 1 is a schematic structural diagram of a pressure sensor with high heat dissipation provided by an embodiment of the present invention.

[0033] Specifically, the pressure sensor includes a housing 1 and a pressure measuring assembly 2, wherein the housing 1 includes an installation cavity 11 for accommodating the pressure measuring assembly 2. The housing 1 also includes a main housing 12 and a pressure connector 13, the pressure connector 13 is used to install the pressure measuring assembly 2, one end of the outer side of the pressure connector 13 is sealed and connected to the inside of a pipe 3 for conveying a fluid medium, and one end of the inner side is connected to the installation cavity 11, so that the medium is introduced into the pressure sensitive element 21 blocked in the pressure channel, and the pressure sensitive element 21 can measure the pressure of the medium.

[0034] Optionally, the pressure measurement component 2 includes a processing element 22 and a pin 23, the pin 23 is inserted into the installation cavity 11 and connected to the processing element 22, and the processing element 22 is connected to the pressure sensitive element 21 through a circuit board, thereby processing the electrical signal of the pressure sensitive element 21 during the pressure measurement process.

[0035] Furthermore, the pressure sensor also includes a cylindrical shell 14 made of metal, one end of which is sealingly connected to the pressure joint 13, so that the inner wall of the cylindrical shell 14, the outer wall of the main shell 12 and the pressure joint 13 together form a heat dissipation channel 15, so that the heat exchange contact area of ​​the heat dissipation channel 15 with the installation cavity 11 is maximized, thereby improving the heat dissipation efficiency.

[0036] Optionally, one end of the shell 14 away from the pipe 3 is rolled inward to form a pressing edge 141, and the pressing edge 141 is installed on the step surface 121 formed by the main shell 12 in a sealed connection manner. For example, the pressing edge 141 and the step surface 121 are sealed by glue, and / or a sealing ring is provided between the pressing edge 141 and the step surface 121 for sealing.

[0037] In some embodiments, the pressure connector 13 can be made of resin material, and the end of the shell 14 facing the pipe 3 can be molded into an inner portion formed at the upper end of the pressure connector 13. Preferably, the end of the shell 14 facing the pipe 3 can be arched outward to form an arched portion 142, which can increase the shell 14 and the corresponding seat 135. The seat 135 is provided with a mounting groove 135a that matches the outer shape of the arched portion 142, and the arched portion 142 is sealed and connected to the mounting groove 135a by plug-in matching.

[0038] Furthermore, a medium inlet channel 132 and a medium outlet channel 133 are formed inside the material of the pressure joint 13; the two ends of the heat dissipation channel 15 are respectively connected to the medium inlet channel 132 and the medium outlet channel 133, and the end of the medium inlet channel 132 away from the heat dissipation channel 15 is connected to the interior of the pipeline 3 on the upstream side (referring to the upstream of the fluid in the pipeline), and the end of the medium outlet channel 133 away from the heat dissipation channel 15 is connected to the interior of the pipeline 3 on the downstream side (referring to the downstream of the fluid in the pipeline), so that the entrance end of the medium inlet channel 132 is set upstream of the pipeline 3, and the discharge end of the medium outlet channel 133 is set downstream of the pipeline 3.

[0039] Meanwhile, the pressure connector 13 includes a pressure introduction channel 131 , and the pressure introduction channel 131 is used for allowing the medium to enter and contact with the pressure sensitive element 21 for pressure detection.

[0040] It is worth noting that the medium used for heat dissipation in the heat dissipation channel 15 of the present invention is the same as the medium used for pressure measurement by the pressure sensitive element, thereby reducing the structural complexity of the present invention.

[0041] It is worth to understand that the description of upstream and downstream is based on the flow direction of the medium in the pipeline 3, and the direction of the arrow in the figure is the flow direction of the medium.

[0042] Optionally, in order to allow the medium to flow smoothly into the heat dissipation channel 15 , a predetermined flow rate is set for the medium to drive the medium into the heat dissipation channel 15 to perform heat exchange with the pressure measurement component 2 .

[0043] Optionally, the pipeline 3 is not an essential technical feature of the present invention, and it is mainly used for the circulation of the supply medium.

[0044] Furthermore, the pressure connector 13 includes a tube body 134 and a seat body 135 located outside the pipeline 3; an outer end of the tube body 134 ( Figure 1 The lower end of the pipe 3 extends into the interior of the pipe 3 and passes inward over the inner wall of the pipe 3. Figure 1 The upper end of the pipe 134 is connected to the seat 135; the end of the seat 135 away from the pipe 3 is sealed and connected to the shell 4. The shape of the pressure joint 13 is configured according to its use requirements so that the pipe 134 can pass over the inner wall of the pipe 3 and enter the pipe 3, and the pipe 134 is connected to the seat 135, and the seat 135 is used to be sealed and connected to the pipe 3.

[0045] Furthermore, a medium inlet 134a is provided on the outer wall of the outer end of the tube body 134 facing the upstream side, and the medium inlet 134a is connected with the end of the medium inlet channel 132 away from the heat dissipation channel 15; a medium outlet 134b is provided on the outer wall of the outer end of the tube body 134 facing the downstream side, and the medium outlet 134b is connected with the end of the medium discharge channel 133 away from the heat dissipation channel 15. The medium inlet 134a is used for the medium to enter and enter the heat dissipation channel 15 along the tube body 134, while the medium outlet 134b is used for the medium that has completed the heat exchange to be discharged from the heat dissipation channel 15. Since the medium inlet 134a faces the flow direction of the medium, it is easy for the medium to enter the heat dissipation channel through the medium inlet 134a. In addition, the medium outlet 134b faces away from the flow direction of the medium and is blocked by the seat body 135.

[0046] Optionally, the medium inlet 134a is a variable diameter structure from large to small, and / or the medium outlet 134b is a variable diameter structure from small to large. The design of the variable diameter structure allows the medium inlet 134a, the heat dissipation channel 15, and the medium outlet 134b to form a flow cross-sectional size change from large to small to large, so that based on the Venturi effect, the flow velocity of the medium flowing in the heat dissipation channel 15 is increased, the heat dissipation efficiency is more significantly improved, and the fluid impact is reduced.

[0047] Furthermore, the medium inlet channel 132 and the medium outlet channel 133 each include a first partial channel (132a, 133a) arranged along the extension direction of the tube body 134 and a second partial channel (132b, 133b) arranged inside the seat body 135. The first partial channel (132a, 133a) and the second partial channel (132b, 133b) are used to adapt to the structural changes of the pressure joint 13.

[0048] In some embodiments, a double-line spiral channel 151 is formed between the outer side wall of the end of the main shell 12 facing the pipeline 3 and the inner side wall of the cylinder shell 14, and the double-line spiral channel 151 includes a first spiral channel 151a and a second spiral channel 151b arranged side by side; the first spiral channel 151a and the second spiral channel 151b are connected at one end away from the tube body 134, the end of the first spiral channel 151a close to the tube body 134 is connected to the medium inlet channel 132, and the end of the second spiral channel 151b close to the tube body 134 is connected to the medium outlet channel 133 (see Figure 2 Schematic diagram of the structure of the double-line spiral groove of the main shell 12).

[0049] Specifically, the medium passes through the first spiral channel 151a, the connecting groove 151c and the second spiral channel 151b in sequence to dissipate heat for the pressure measurement component 2. Since the first spiral channel 151a and the second spiral channel 151b are arranged side by side and connected through the connecting groove 151c in the middle section, the medium just entering is arranged side by side with the medium to be discharged, thereby improving the uniformity of the heat exchange of the medium.

[0050] It is worth noting that the double-line spiral groove is part of the double-line spiral channel 151 , which is formed by a double-line spiral groove provided on the outer side wall of the main shell 12 facing one end of the pipeline and the interior of the cylinder shell 14 .

[0051] Optionally, a double-helical groove is provided on the outer side wall of the end of the main shell 12 facing the pipeline 3 , and a double-helical channel 151 is formed between the double-helical groove and the inner wall of the cylinder shell 14 .

[0052] Optionally, one end of the double-line spiral groove close to the tube body 134 is connected to the end surface of the main shell 12 facing the pipeline 3 through a connecting groove 151c extending toward the side of the seat body 135, and the connecting groove 151c is connected to the upper end of the corresponding medium inlet channel 132 or the medium discharge channel 133.

[0053] The cylindrical shell 14 is punched and stretched inward to form a stretched portion, which surrounds a double-line spiral groove. The stretched portion and the outer side wall of the main shell 12 at one end facing the pipeline 3 form a double-line spiral channel 151 corresponding to the double-line spiral groove.

[0054] Optionally, the heat dissipation channel 15 may be configured in a double-line spiral shape or a side-by-side U-shaped shape, a ring shape, etc.

[0055] Optionally, the heat dissipation channels 15 are arranged in the vertical direction or the horizontal direction of the space.

[0056] In some embodiments, the end of the cartridge shell 14 facing the pipeline 3 is integrally molded into the pressure interface.

[0057] Optionally, one end of the cylindrical shell 14 away from the pipeline 3 is rolled inward to form a circle of pressing edge, and the pressing edge is pressed downward and sealingly against a step surface formed on the main shell 12.

[0058] Furthermore, a sealing gasket is provided between the pressing edge and the step surface to enhance the sealing effect between the two.

[0059] Optionally, the medium is a fluid substance such as gas, liquid, or semi-solid.

[0060] In the above embodiments, the main housing 12 may be a metal component, and further, the housing 1 is a metal component.

[0061] The present invention is described in detail above. The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the present invention and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A pressure sensor with high heat dissipation efficiency, characterized in that: The pressure sensor comprises: A housing (1) having an installation cavity (11) comprises a main housing (12) and a pressure joint (13) having a pressure introduction channel (131) formed therein; an outer end of the pressure joint (13) is sealedly connected to the interior of a pipe (3) for conveying a flowing pressure medium to be measured, and an inner end is connected to the installation cavity (11); a medium inlet channel (132) and a medium outlet channel (133) are formed inside the material of the pressure joint (13); A pressure measuring assembly (2) disposed in the installation cavity (11), comprising a pressure sensitive element (21) sealed at one end of the inner side of the pressure introduction channel (131) to measure the pressure of the fluid medium; and a metal cylindrical shell (14) having one end sealedly fixed to the pressure joint (13); a heat dissipation channel (15) is formed between the cylindrical shell, the main shell (12) and the pressure joint (13); two ends of the heat dissipation channel (15) are respectively connected to the medium inlet channel (132) and the medium outlet channel (133); an end of the medium inlet channel (132) away from the heat dissipation channel (15) is connected to the interior of the pipeline (3) toward the upstream side, and an end of the medium outlet channel (133) away from the heat dissipation channel (15) is connected to the interior of the pipeline (3) toward the downstream side.

2. A pressure sensor with high heat dissipation efficiency according to claim 1, characterized in that: The pressure joint (13) comprises a tube body (134) and a seat body (135) located outside the pipeline (3); an outer end of the tube body (134) extends into the interior of the pipeline (3) and inwardly passes over the inner wall of the pipeline (3), and an inner end thereof is connected to the seat body (135); an end of the seat body (135) away from the pipeline (3) is sealingly connected to the metal cylinder shell (14).

3. A pressure sensor with high heat dissipation efficiency according to claim 2, characterized in that: A medium inlet (134a) is provided on the outer wall of the outer end of the tube body (134) facing the upstream side of the pipeline (3), and the medium inlet (134a) is communicated with the end of the medium inlet channel (132) away from the heat dissipation channel (15); a medium outlet (134b) is provided on the outer wall of the outer end of the tube body (134) facing the downstream side of the pipeline (3), and the medium outlet (134b) is communicated with the end of the medium discharge channel (133) away from the heat dissipation channel (15).

4. A pressure sensor with high heat dissipation efficiency according to claim 3, characterized in that: The medium inlet channel (132) and the medium outlet channel (133) both comprise a first partial channel (132a, 133a) arranged along the extension direction of the tube body (134) and a second partial channel (132b, 133b) arranged inside the seat body (135).

5. The pressure sensor with high heat dissipation efficiency according to claim 1, characterized in that: The heat dissipation channel (15) comprises a double-line spiral channel (151) formed between the outer side wall of the main shell (12) facing the pipeline (3) and the inner side wall of the cylinder shell, and the double-line spiral channel (151) comprises a first spiral channel (151a) and a second spiral channel (151b) arranged side by side with the first spiral channel (151a). The first spiral channel (151a) and the second spiral channel (151b) are connected at one end away from the tube body (134), the end of the first spiral channel (151a) close to the tube body (134) is connected to the medium inlet channel (132), and the end of the second spiral channel (151b) close to the tube body (134) is connected to the medium outlet channel (133).

6. A pressure sensor with high heat dissipation efficiency according to claim 5, characterized in that: A double-helical groove is provided on the outer side wall of one end of the main shell (12) facing the pipeline (3), and the double-helical groove and the inner wall of the cylinder shell form the double-helical channel (151).

7. A pressure sensor with high heat dissipation efficiency according to claim 6, characterized in that: One end of the double-helical groove close to the tube body (134) is connected to the end surface of the main shell (12) facing the pipeline (3) through a connecting groove (151c) extending toward one side of the seat body (135), and the connecting groove (151c) is connected to the upper end of the corresponding medium inlet channel (132) or medium outlet channel (133).

8. The pressure sensor with high heat dissipation efficiency according to claim 1, characterized in that: The shell is punched and stretched inward to form a stretching portion, the stretching portion encloses a double-helical groove, and a double-helical channel (151) corresponding to the double-helical groove is enclosed between the stretching portion and the outer side wall of the main shell (12) at one end facing the pipeline (3).

9. A pressure sensor with high heat dissipation efficiency according to any one of claims 1 to 8, characterized in that: One end of the cylindrical shell facing the pipeline (3) is integrally molded in the pressure interface.

10. The pressure sensor with high heat dissipation efficiency according to any one of claims 1 to 8, characterized in that: One end of the cylindrical shell away from the pipeline (3) is rolled inward to form a circle of pressing edge, and the pressing edge is pressed downward and sealingly against a step surface formed on the main shell (12).

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