Dual-current sensor based on diverter fused with tunnel reluctance technology

Abstract

The invention provides a dual-current sensor based on shunt fusion tunnel magnetoresistive technology, and relates to the technical field of sensors, the dual-current sensor comprises a conductor, a first sensor, a second sensor and a third sensor, the first sensor is a shunt sensor, and the second sensor and the third sensor are tunnel magnetoresistive sensors. The second sensor and the third sensor are respectively arranged on two opposite sides of the conductor; the device further comprises a first circuit board, the first sensor is arranged on the first circuit board, and the first circuit board and the first sensor are both connected with the conductor. The second circuit board is used for acquiring data of the second sensor and the third sensor, the first circuit board is provided with a differential circuit, and the differential circuit is used for receiving the data of the second sensor and the third sensor and eliminating environmental interference; the sensor further comprises a shell and a second circuit board, the second sensor and the third sensor are arranged in the shell, the conductor penetrates through the shell, and the shell is fixedly connected with the first circuit board. Environmental interference can be effectively resisted, and the size is reduced.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a dual current sensor based on shunt-fused tunnel magnetoresistive technology. Background Technology

[0002] Currently, current sensors are widely used in various technical fields. Especially with the development of electric vehicles, current sensors are widely used and play a crucial role in battery packs or battery management systems (BMS). Common current sensors use precision resistors to directly detect voltage drop and calculate current; these are also known as shunts. Hall effect current sensors, based on the Hall effect principle, are also a commonly used type of current sensor.

[0003] In environments with high precision requirements and high interference, there are composite current sensors that combine a shunt and a Hall effect current sensor. These sensors measure the current separately using both methods before calculation. Because the two measurement methods operate on different principles, they effectively prevent interference from environmental factors such as high temperatures and complex electromagnetic environments. Therefore, this composite current sensor can achieve more accurate current measurement results. However, the Hall effect current sensor requires a magnet, resulting in a relatively large size. With the trend towards miniaturization of electronic components, this composite current sensor faces many obstacles in practical applications. Summary of the Invention

[0004] The purpose of this invention is to provide a dual current sensor based on shunt-integrated tunnel magnetoresistive technology, which solves the technical problem of large size of composite current sensors in the prior art.

[0005] This invention provides a dual current sensor based on shunt fusion tunnel magnetoresistive technology, comprising a conductor, a first sensor, a second sensor, and a third sensor. The first sensor is a shunt sensor, and the second and third sensors are tunnel magnetoresistive sensors. The second and third sensors are respectively disposed on opposite sides of the conductor. It also includes a first circuit board, a first sensor disposed on the first circuit board, and both the first circuit board and the first sensor are connected to a conductor; It also includes a second circuit board, which is used to acquire data from the second and third sensors. The first circuit board is provided with a differential circuit, which is used to receive data from the second and third sensors and eliminate environmental interference. It also includes a housing, and the second circuit board, the second sensor and the third sensor are all located inside the housing. The conductor passes through the housing, and the housing and the first circuit board are fixedly connected.

[0006] In an optional embodiment, a limiting structure is provided between the first circuit board and the housing. The limiting structure includes a first limiting part provided on the first circuit board and a second limiting part provided on the housing. The first limiting part and the second limiting part cooperate with each other to limit the first circuit board and the housing.

[0007] In an optional embodiment, the first limiting part is a limiting groove provided on the first circuit board, and the second limiting part is a limiting block provided on the outer shell, with the limiting block disposed in the limiting groove.

[0008] In an optional embodiment, the housing includes a first housing and a second housing, which are respectively snapped together from opposite sides of the first circuit board.

[0009] In an optional embodiment, the first housing is provided with a first upper support and a first lower support, and an open area is formed between the first upper support and the first lower support to allow the conductor to pass through.

[0010] In an optional embodiment, both the lower surface of the upper support and the upper surface of the lower support are in contact with the conductor.

[0011] In an optional embodiment, the second circuit board is arranged perpendicular to the conductor, and both the second sensor and the third sensor are disposed on the second circuit board. The second circuit board has an opening, and the second circuit board is sleeved on the first upper support and the first lower support through the opening.

[0012] In an optional embodiment, the first upper support and the first lower support extend from the first sidewall of the first housing to the second sidewall, and the distance between the first upper support and the first lower support and the second sidewall is not less than the thickness of the circuit board.

[0013] In an optional embodiment, the second housing is provided with a lateral positioning part, which abuts against the second circuit board when the first housing is connected to the second housing.

[0014] In an optional embodiment, the second circuit board is provided with a connection port, and the front end of the second housing is provided with a port opening, through which the connection port protrudes from inside the housing.

[0015] The dual current sensor based on shunt fusion tunnel magnetoresistive technology provided by this invention has the following beneficial effects: 1. This invention employs a composite sensor combining a shunt sensor and a tunnel magnetoresistive sensor. The tunnel magnetoresistive sensor detects current by acquiring the magnetic field signal of current flowing through a conductor. At the same time, the tunnel magnetoresistive sensor has a much smaller volume than a Hall sensor, which can realize the miniaturization of the sensor. 2. In this invention, the second and third sensors are respectively placed on opposite sides of the conductor, and a differential circuit is used to receive the data from the second and third sensors and eliminate environmental interference. The differential circuit, together with the second and third sensors, can solve the electromagnetic interference in the application environment. At the same time, it can also use two types of sensors, namely shunt sensors and tunnel magnetoresistive sensors, to solve different types of interference, thereby further improving the overall anti-interference capability of the sensor system. 3. In this invention, the second circuit board, the second sensor, and the third sensor are all housed inside the housing, with conductors passing through the housing. The housing and the first circuit board are fixedly connected. This structure can improve the ease of installation of the second circuit board, the second sensor, and the third sensor, while ensuring the fixation effect of the housing. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of a dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the second circuit board in a dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the hidden shell structure of a dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of the first housing in the dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention; Figure 5 A schematic diagram of the combined state of the first housing and the second circuit board in a dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the second housing in a dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention; Figure 7 A side view of a dual current sensor based on shunt-fused tunnel magnetoresistive technology provided in an embodiment of the present invention; Figure 8 for Figure 7 Sectional view at point AA; Figure 9 for Figure 7 Sectional view at point BB.

[0018] Icons: 100 - Conductor; 200 - First circuit board; 210 - Limiting groove; 300 - Second circuit board; 310 - Second sensor; 320 - Third sensor; 330 - Connection port; 400 - Housing; 410 - First housing; 411 - Limiting block; 412 - First upper support; 413 - First lower support; 414 - First sidewall; 415 - Second sidewall; 420 - Second housing; 421 - Lateral positioning part; 422 - Port opening. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] This invention provides a dual current sensor based on shunt-integrated tunnel magnetoresistive technology, such as... Figure 1 , Figure 2 and Figure 3 As shown, the system includes a conductor 100, a first sensor, a second sensor 310, and a third sensor 320. The first sensor is a shunt sensor, and the second and third sensors 310 and 320 are tunnel magnetoresistive sensors, respectively located on opposite sides of the conductor 100. It also includes a first circuit board 200, on which the first sensor is disposed, and both the first circuit board 200 and the first sensor are connected to the conductor 100. Furthermore, it includes a second circuit board 300, used to acquire data from the second and third sensors 310 and 320. The first circuit board 200 is equipped with a differential circuit, used to receive data from the second and third sensors 310 and eliminate environmental interference. Finally, it includes a housing 400, within which the second circuit board 300, the second sensor 310, and the third sensor 320 are all housed. The conductor 100 passes through the housing 400, and the housing 400 and the first circuit board 200 are fixedly connected.

[0027] in, Figure 1 This is a schematic diagram of the overall structure of a dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the second circuit board 300 in the dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in an embodiment of the present invention, showing the positional relationship between the second sensor 310 and the third sensor 320; Figure 3The schematic diagram of the hidden housing 400 in the dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in the embodiment of the present invention shows the positional relationship of the first circuit board 200, the second sensor 310, the third sensor 320 and the conductor 100.

[0028] The shunt sensor employs a precision resistor soldered to a conductor 100. The current signal flowing through the conductor 100 is obtained by measuring the precision resistance. The first circuit board 200 can be soldered to the conductor 100 and electrically connected to the precision resistor using methods such as vacuum phase soldering to obtain the current signal from the precision resistor. This technology is conventional. Figure 1 and Figure 3 As shown in the figure, the connection between the precision resistor and the conductor 100, and the connection between the precision resistor and the first circuit board 200 are not illustrated in detail, but the positional relationship between the first circuit board 200 and the conductor 100 is shown.

[0029] like Figure 1 and Figure 3 As shown, in this embodiment, conductor 100 is a conductive busbar, which can be a conductive copper busbar, a conductive aluminum busbar, etc., all of which are applicable in this embodiment. In other embodiments, conductor 100 can also be in other forms, such as cylindrical, etc., and this application does not limit this.

[0030] like Figure 3 As shown, the second sensor 310 and the third sensor 320 are respectively disposed on the upper and lower sides of the conductor 100, and this arrangement is based on the structure of the conductive busbar. In other embodiments, depending on the specific form of the conductor 100, the second sensor 310 and the third sensor 320 can be disposed in other specific locations.

[0031] In this embodiment, a composite sensor system combining a shunt sensor and a tunneling magnetoresistive sensor is employed. The tunneling magnetoresistive sensor detects current by acquiring the magnetic field signal of current flowing through conductor 100. The tunneling magnetoresistive sensor is a magnetic sensor based on the quantum tunneling effect, and it has a much smaller volume than a Hall sensor, enabling the miniaturization of a dual-current sensor based on a shunt fusion tunneling magnetoresistive technology. In particular, compared to Hall sensors, the elimination of the magnet significantly reduces the structural footprint.

[0032] like Figure 3As shown, in this embodiment, the second sensor 310 and the third sensor 320 are respectively disposed on opposite sides of the conductor 100, and a differential circuit is used to receive the data from the second sensor 310 and the third sensor 320 and eliminate environmental interference. The differential circuit, together with the second sensor 310 and the third sensor 320, can solve the electromagnetic interference in the application environment. At the same time, it can also use two types of sensors, namely shunt sensors and tunnel magnetoresistive sensors, to solve different types of interference, thereby further improving the overall anti-interference capability of the sensor system.

[0033] like Figure 1 and Figure 3 As shown, the present invention houses the second circuit board 300, the second sensor 310, and the third sensor 320 within the housing 400. The conductor 100 passes through the housing 400, and the housing 400 is fixedly connected to the first circuit board 200. This structure can improve the ease of installation of the second circuit board 300, the second sensor 310, and the third sensor 320, while ensuring the fixation effect of the housing 400.

[0034] In this embodiment, as Figure 1 , Figure 4 and Figure 6 As shown, the outer casing 400 includes a first casing 410 and a second casing 420, which are respectively fastened together from opposite sides of the first circuit board 200. Specifically, with Figure 1 Taking the position as an example, the first housing 410 is engaged with the second housing 420 from the front to the rear. The specific engagement structure can be set in multiple groups or a single group, or it can be located on the inner or outer side of the housing 400, such as... Figure 1 , Figure 4 and Figure 6 As shown, in this embodiment, four sets of snap-fit ​​structures are provided, with snap-fit ​​structures on the upper and lower parts of the outer shell 400 and on the left and right sides of the outer shell 400. In other embodiments, corresponding snap-fit ​​structures can be set according to specific requirements.

[0035] like Figure 3 and Figure 4 As shown, in this embodiment, a limiting structure is provided between the first circuit board 200 and the housing 400. The limiting structure includes a first limiting part disposed on the first circuit board 200 and a second limiting part disposed on the housing 400. The first limiting part and the second limiting part cooperate to limit the first circuit board 200 and the housing 400. The first limiting part is a limiting groove 210 disposed on the first circuit board 200, and the second limiting part is a limiting block 411 disposed on the housing 400. Specifically, the limiting block 411 is located on the first housing 410 and is disposed within the limiting groove 210. The cooperation between the limiting groove 210 and the limiting block 411 can realize the limiting and positioning of the housing 400 and the first circuit board 200.

[0036] In this embodiment, as Figure 6 As shown, a limiting structure is also provided between the second housing 420 and the first circuit board 200. The second housing 420 is provided with a limiting block 411, and the first circuit board 200 is also provided with a corresponding limiting groove 210. The two cooperate to ensure that the second housing 420 can be accurately positioned when it is engaged with the first housing 410, preventing the second housing 420 from shifting position and ensuring the accurate installation of the outer casing 400. In other embodiments, a limiting structure may only be provided between the first housing 410 and the first circuit board 200.

[0037] In this embodiment, as Figure 4 and Figure 8 As shown, the first housing 410 has a first upper support portion 412 and a first lower support portion 413, forming an open area between the first upper support portion 412 and the first lower support portion 413 that allows the conductor 100 to pass through. The lower surface of the upper support portion and the upper surface of the lower support portion both abut against the conductor 100. The first upper support portion 412 and the first lower support portion 413 extend from the first sidewall 414 of the first housing 410 to the second sidewall 415. Figure 8 The cross-sectional view shows the connection status of the first housing 410, conductor 100, and first circuit board 200.

[0038] The conductor 100 passes through the housing by having an opening on the outer casing 400. In this embodiment, the conductor 100 is in the form of a busbar, providing a large upper and lower surface area. Therefore, the first upper support 412 and the first lower support 413 can abut against the conductor 100, thereby further ensuring the stable installation of the outer casing 400. The first upper support 412 and the first lower support 413 are disposed on the first side wall 414 of the first casing 410. Correspondingly, the second side wall 415 of the first casing 410 also has a corresponding opening, allowing the conductor 100 and the first circuit board 200 to pass through. Furthermore, the upper and lower surfaces of the opening on the second side wall 415 can be respectively engaged with the conductor 100 and the first circuit board 200 to further increase the connection stability of the outer casing 400.

[0039] like Figure 6 As shown, the second housing 420 is provided with a second upper support and a second lower support. The second upper support and the second lower support are respectively provided with the first upper support 412 and the first lower support 413. Thus, when the first housing 410 and the second housing 420 are connected, the second upper support and the first upper support 412 and the second lower support and the first lower support 413 can be connected respectively to further increase the connection stability of the housing 400.

[0040] In other embodiments, the second housing 420 may also omit the second upper support and the second lower support.

[0041] In this embodiment, as Figure 2 , Figure 3 and Figure 5 As shown, the second circuit board 300 is arranged perpendicular to the conductor 100. Both the second sensor 310 and the third sensor 320 are mounted on the second circuit board 300. The second circuit board 300 has an opening, through which it is fitted onto the first upper support portion 412 and the first lower support portion 413. Mounting both the second sensor 310 and the third sensor 320 on the second circuit board 300 simplifies their mounting structure, allowing for direct positioning of the sensors. Furthermore, the opening within the first upper support portion 412 and the first lower support portion 413 also allows for fixation of the second circuit board 300, further simplifying its fixing structure.

[0042] like Figure 4 , Figure 5 and Figure 8 As shown, the distances between the first upper support 412 and the first lower support 413 and the second sidewall 415 are both not less than the thickness of the circuit board, allowing the second circuit board 300 to pass through this distance into the first housing 410. The first housing 410 only needs one opening, eliminating the need for other opening structures, thus simplifying the structure of the first housing 410 and the installation steps of the second circuit board 300 and the first housing 410. Figure 4 As shown, the first upper support portion 412 and the first lower support portion 413 do not extend to the rear end face of the first housing 410, but instead retain mounting space for the second circuit board 300 to be inserted through the opening. The second circuit board 300 can first be inserted entirely into the first housing 410 through the position between the first upper support portion 412 and the first lower support portion 413 and the second sidewall 415, and then moved laterally so that the second circuit board 300 is fitted onto the first upper support portion 412 and the first lower support portion 413 through the opening.

[0043] In this embodiment, as Figure 6 and Figure 9As shown, the second housing 420 is provided with a lateral positioning part 421. When the first housing 410 is connected to the second housing 420, the lateral positioning part 421 abuts against the second circuit board 300, thereby achieving lateral fixation of the second circuit board 300. In this way, the installation and fixing process of the second circuit board 300 does not require the use of glue, welding or other additional fixing methods. The installation and fixing of the second circuit board 300 can be achieved solely by relying on the internal structure of the first housing 410 and the second housing 420, which greatly simplifies the installation structure and installation steps of the second circuit board 300.

[0044] like Figure 1 and Figure 9 As shown, in this embodiment, the second circuit board 300 is provided with a connection port 330, and the front end of the second housing 420 is provided with a port opening 422. The connection port 330 protrudes from the housing 400 through the port opening 422. Figure 9 As shown, the upper surface of the lateral positioning part 421 can also form a support part for the connection port 330.

[0045] For the dual current sensor based on shunt fusion tunnel magnetoresistive technology provided in this embodiment, a preferred installation method is to first install the second circuit board 300 and the first housing 410 to form a component, then install the component with the conductor 100 and the pre-installed parts of the first sensor and the first circuit board 200, and finally snap the second housing 420 and the first housing 410 together.

[0046] In some embodiments, a temperature sensor may also be provided on the first circuit board 200, thereby using an algorithm to eliminate the influence of temperature on the detection accuracy of the first sensor.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-current sensor based on shunt-integrated tunnel magnetoresistive technology, characterized in that, It includes a conductor (100), a first sensor, a second sensor (310) and a third sensor (320). The first sensor is a shunt sensor, and the second sensor (310) and the third sensor (320) are tunnel magnetoresistive sensors. The second sensor (310) and the third sensor (320) are respectively disposed on opposite sides of the conductor (100). It also includes a first circuit board (200), the first sensor is disposed on the first circuit board (200), and both the first circuit board (200) and the first sensor are connected to the conductor (100); It also includes a second circuit board (300) for acquiring data from a second sensor (310) and a third sensor (320), and the first circuit board (200) is provided with a differential circuit for receiving data from the second sensor (310) and the third sensor (320) and eliminating environmental interference; It also includes a housing (400), the second circuit board (300), the second sensor (310) and the third sensor (320) are all disposed inside the housing (400), the conductor (100) passes through the housing (400), and the housing (400) and the first circuit board (200) are fixedly connected.

2. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 1, characterized in that, A limiting structure is provided between the first circuit board (200) and the outer shell (400). The limiting structure includes a first limiting part provided on the first circuit board (200) and a second limiting part provided on the outer shell (400). The first limiting part and the second limiting part cooperate with each other to limit the first circuit board (200) and the outer shell (400).

3. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 2, characterized in that, The first limiting part is a limiting groove (210) provided on the first circuit board (200), and the second limiting part is a limiting block (411) provided on the outer shell (400), and the limiting block (411) is provided in the limiting groove (210).

4. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 1, characterized in that, The outer casing (400) includes a first casing (410) and a second casing (420), which are respectively fastened to each other from opposite sides of the first circuit board (200).

5. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 4, characterized in that, The first housing (410) is provided with a first upper support portion (412) and a first lower support portion (413), and an open area is formed between the first upper support portion (412) and the first lower support portion (413) to allow the conductor (100) to pass through.

6. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 5, characterized in that, The lower surface of the upper support and the upper surface of the lower support both abut against the conductor (100).

7. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 5, characterized in that, The second circuit board (300) is arranged perpendicular to the conductor (100). The second sensor (310) and the third sensor (320) are both arranged on the second circuit board (300). The second circuit board (300) has an opening. The second circuit board (300) is sleeved on the first upper support (412) and the first lower support (413) through the opening.

8. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 7, characterized in that, The first upper support portion (412) and the first lower support portion (413) extend from the first side wall (414) of the first housing (410) to the second side wall (415), and the distance between the first upper support portion (412) and the first lower support portion (413) and the second side wall (415) is not less than the thickness of the circuit board.

9. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 8, characterized in that, The second housing (420) is provided with a lateral positioning part (421). When the first housing (410) is connected to the second housing (420), the lateral positioning part (421) abuts against the second circuit board (300).

10. The dual current sensor based on shunt-fused tunnel magnetoresistive technology according to claim 4, characterized in that, The second circuit board (300) is provided with a connection port (330), and the front end of the second housing (420) is provided with a port opening (422). The connection port (330) is exposed from the housing (400) through the port opening (422).

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