Double-air-gap Hall sensor

Abstract

A double-air-gap Hall sensor relates to the technical field of Hall current sensors and is used for reducing the size and cost of the double-air-gap Hall sensor. The double-air-gap Hall sensor comprises a C-shaped magnetic core, a shell, a Hall chip and a PCB (Printed Circuit Board); the number of the C-shaped magnetic cores is two, and the ends of the two C-shaped magnetic cores are oppositely arranged so that two air gaps can be formed between the two C-shaped magnetic cores. The shell is integrally formed outside the two C-shaped magnetic cores, an avoiding cavity corresponding to one air gap is formed in the shell, a detection cavity is formed in the shell and located in the middle of the two C-shaped magnetic cores, and the opening direction of the detection cavity is perpendicular to the distribution direction of the two C-shaped magnetic cores and the distribution direction of the two air gaps; at least part of the Hall chip extends into the avoiding cavity; the PCB is arranged on the shell, and the Hall chip is arranged on the PCB. Through the shell and the two C-shaped magnetic cores which are integrally formed, the installation difficulty of the C-shaped magnetic cores can be reduced, the assembly precision is improved, and the size of the Hall sensor is reduced.

Description

Technical Field

[0001] This application relates to the field of Hall current sensor technology, and more particularly to a dual-air-gap Hall sensor. Background Technology

[0002] An open-loop Hall current sensor is a non-contact current detection device based on the Hall effect principle. Its core structure includes a magnetic core and a Hall element. The magnetic core is bent to form an air gap between its ends. The function of the magnetic core is to concentrate the magnetic field generated by the measured current, and the current is indirectly measured by the change in magnetic field strength at the air gap.

[0003] Chinese patent publication number CN213843365U, filed on November 25, 2020, discloses a dual-air-gap Hall current sensor. This patent forms a dual-air-gap structure by splitting the middle of the magnetic core again, which improves the magnetic field sensing range, expands the measurement range, and alleviates the saturation problem of a single-air-gap magnetic core to a certain extent.

[0004] However, the two magnetic cores that form the two air gaps in this structure are manufactured independently and then fixed with bolts. The outer shells of the two magnetic cores also need to be welded together. This not only requires high welding technology, but also leads to an increase in the size of the sensor and a surge in material costs. Utility Model Content

[0005] This application provides a dual-gap Hall sensor to reduce the size and cost of dual-gap Hall sensors.

[0006] This application provides a dual-air-gap Hall sensor, including a C-shaped magnetic core, a housing, a Hall chip, and a PCB board; two C-shaped magnetic cores are provided, with their ends facing each other to form two air gaps between them; the housing is integrally formed outside the two C-shaped magnetic cores, and a clearance cavity is formed on the housing corresponding to one air gap; a detection cavity is formed on the housing at the middle of the two C-shaped magnetic cores, and the opening direction of the detection cavity is perpendicular to the distribution direction of the two C-shaped magnetic cores and the distribution direction of the two air gaps; the Hall chip extends at least partially into the clearance cavity; the PCB board is disposed on the housing, and the Hall chip is disposed on the PCB board.

[0007] In this application, the two C-shaped magnetic cores are directly fixed to the housing by integral molding, avoiding the increased volume caused by bolt or snap-fit ​​assembly, and also avoiding precision issues during assembly. The two C-shaped magnetic cores in this solution adopt a double air gap structure, which can increase the conduction and dispersion of magnetic flux, so that the magnetic cores require a higher magnetic field strength to reach saturation, thus leading to a delayed magnetic saturation. The Hall sensor uses only one Hall chip, which can sense the circuit located in the detection cavity within the two magnetic cores to achieve the purpose of current detection. Compared with installing Hall chips at each air gap, this solution reduces material costs and installation difficulty, and helps to further reduce the size of the sensor.

[0008] In some embodiments of this application, the C-shaped magnetic core includes a main body, a short bend, and a long bend. The short bend and the long bend are located on the same side of the main body, and the length of the long bend is greater than the length of the short bend. This structure allows the C-shaped magnetic core to be formed in both directions, facilitating positioning during installation. Simultaneously, this structure enables the current between two C-shaped magnetic cores to generate the desired magnetic field effect in the air gap.

[0009] In some embodiments of this application, the two air gaps include a main air gap and a secondary air gap. The main air gap is formed between the two short bends of the two C-shaped magnetic cores, and the secondary air gap is formed between the two long bends of the two C-shaped magnetic cores. The detection cavity is disposed at the main air gap.

[0010] The main air gap is used to install the Hall chip. Its larger gap facilitates the installation and positioning of the Hall chip. The secondary air gap can limit the outflow of magnetic flux to a certain extent, thereby enhancing the sensor's ability to resist external interference. At the same time, it can also utilize the characteristics of magnetic flux change brought about by the dual air gaps to make it more difficult for the magnetic core to reach magnetic saturation, thereby delaying the occurrence of magnetic saturation.

[0011] In some embodiments of this application, a receiving groove is formed on the housing for mounting a PCB board, and the receiving groove communicates with a clearance cavity. The receiving groove facilitates the installation and fixation of the PCB board.

[0012] In some embodiments of this application, two C-shaped magnetic cores and one Hall chip constitute a detection unit. Three detection units are configured, spaced apart along the distribution direction of the two C-shaped magnetic cores, and the three Hall chips of the three detection units are mounted on the same PCB board. Each of the three detection units can be connected to one of three current paths, thereby broadening the applicability of the Hall sensor, for example, enabling direct detection of three-phase electricity.

[0013] In some embodiments of this application, the gaps between any two adjacent detection units are equal. Equal gaps between adjacent detection units allow for a more regular and rational layout of all C-type magnetic cores, contributing to improved consistency of current detection results.

[0014] In some embodiments of this application, all C-shaped magnetic cores of the three detection units are integrated into the same housing. All C-shaped magnetic cores are simultaneously housed within the housing through a single molding process, which reduces manufacturing complexity and improves the positional accuracy of the C-shaped magnetic cores.

[0015] In some embodiments of this application, three detection units constitute a three-phase detection assembly, which is configured as two groups. The two groups of three-phase detection assemblies are spaced apart along the distribution direction of any two C-shaped magnetic cores. The two groups of three-phase detection assemblies can simultaneously detect the same three-phase circuit, so that if one group of three-phase detection assemblies fails, the circuit can be directly tested through the other group of three-phase detection assemblies, which helps to improve the fault tolerance of the equipment and reduce the repair and replacement rate.

[0016] In some embodiments of this application, the dual-gap Hall sensor further includes a communication terminal soldered to a PCB board, with one end extending outside the housing. The communication terminal facilitates the connection between the circuitry on the PCB board and the outside world. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the technical solution of this utility model and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solution of this utility model and do not constitute a limitation on the technical solution of this utility model.

[0018] Figure 1 This is a partial exploded view of a dual-gap Hall sensor provided in an embodiment of this application.

[0019] Figure 2 An exploded view of a dual-gap Hall sensor provided in an embodiment of this application.

[0020] Figure 3 This is a schematic diagram of a dual-gap Hall sensor provided in an embodiment of this application.

[0021] Reference numerals: 1-C-type magnetic core; 11-Main body; 12-Short bend; 13-Long bend; 2-Air gap; 21-Main air gap; 22-Secondary air gap; 3-Housing; 31-Allowing cavity; 32-Detection cavity; 33-Receiving groove; 4-Hall chip; 5-PCB board; 6-Detection unit; 7-Three-phase detection assembly; 8-Communication terminal; 9-Encapsulation layer. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, when describing pipelines, the terms "connected" and "linked" as used in this application have the meaning of establishing electrical connection. The specific meaning needs to be understood in conjunction with the context.

[0026] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0027] An open-loop Hall current sensor is a non-contact current detection device based on the Hall effect principle. Its core structure includes a magnetic core and a Hall element. The magnetic core is bent to form an air gap between its ends. The function of the magnetic core is to concentrate the magnetic field generated by the measured current, and the current is indirectly measured by the change in magnetic field strength at the air gap.

[0028] Chinese patent publication number CN213843365U, filed on November 25, 2020, discloses a dual-air-gap Hall current sensor. This patent forms a dual-air-gap structure by splitting the middle of the magnetic core again, which improves the magnetic field sensing range, expands the measurement range, and alleviates the saturation problem of a single-air-gap magnetic core to a certain extent.

[0029] However, the two magnetic cores that form the two air gaps in this structure are manufactured independently and then fixed with bolts. The outer shells of the two magnetic cores also need to be welded together. This not only requires high welding technology, but also leads to an increase in the size of the sensor and a surge in material costs.

[0030] Therefore, please refer to Figure 1 This application provides a dual air gap Hall sensor, including a C-shaped magnetic core 1, a housing 3, a Hall chip 4, and a PCB board 5.

[0031] Please refer to Figure 1 Two C-type magnetic cores 1 are provided, with their ends facing each other to form two air gaps 2 between them. The two C-type magnetic cores 1 can be identical and can be arranged axially symmetrically; the C-type magnetic cores 1 can be made of a material such as manganese zinc ferrite.

[0032] Please refer to Figure 1 The dual air gap can effectively improve the detection range. Under the same volume, the dual air gap has a longer effective magnetic circuit than the single air gap, and the range can be 30-50% larger than that of the single air gap. At this time, the two air gaps 2 can be located at the two ends of each C-type magnetic core 1. The two air gaps 2 only refer to the space between the two ends of the C-type magnetic core 1. The area between the two C-type magnetic cores 1 does not refer to the air gap.

[0033] Please refer to Figure 1 The two air gaps 2 can be the same width or different widths; that is, the distance between the two close ends of the two C-shaped magnetic cores 1 can be the same or different.

[0034] Please refer to Figure 1 The housing 3 is integrally formed on the outside of the two C-shaped magnetic cores 1. A clearance cavity 31 is formed on the housing 3 corresponding to an air gap 2. A detection cavity 32 is formed on the housing 3 in the middle of the two C-shaped magnetic cores 1. The opening direction of the detection cavity 32 is perpendicular to the distribution direction of the two C-shaped magnetic cores 1 and the distribution direction of the two air gaps 2.

[0035] Please refer to Figure 1The housing 3 can be made of injection-molded material, such as plastic. In this case, the C-shaped magnetic core 1 can be fixed in a designated position through a positioning structure, and the C-shaped magnetic core 1 and the housing 3 can be directly integrally formed by injection molding using a corresponding mold. This molding structure can effectively reduce the overall volume of the housing 3, and can fix the relative position between the two C-shaped magnetic cores 1, with high assembly precision.

[0036] The clearance cavity 31 and the detection cavity 32 can be realized through mold design. The clearance cavity 31 can penetrate the housing 3 on one side, or it can penetrate the housing 3 along the opening direction of the detection cavity 32. The magnetic core contour positioning groove on the mold can ensure that the position of the magnetic core will not change significantly during integral injection molding; and the positional deviation of the C-shaped magnetic core 1 after integral injection molding is consistent. The above-mentioned possible deviations can also be corrected by chip programming in the calibration process after the sensor is manufactured.

[0037] Please refer to Figure 1 The width of the clearance cavity 31 should be smaller than the width of the air gap 2. At this time, the outer shell should cover the end area of ​​the C-type magnetic core 1 to facilitate the positioning of the C-type magnetic core 1 and provide a certain degree of protection for the C-type magnetic core 1.

[0038] Since there are two air gaps 2 between the two C-type magnetic cores 1, the avoidance cavity 31 can be formed for only one air gap 2, or an avoidance cavity 31 can be formed at each air gap 2; only one Hall chip 4 is set. When there are two avoidance cavities 31, it can be set in one of the avoidance cavities 31.

[0039] The detection cavity 32 is used to set the circuit of the current to be detected, so that when current flows through it, the two C-shaped magnetic cores 1 and the Hall sensor can generate a corresponding effect to detect the current intensity.

[0040] Please refer to Figure 1 The Hall chip 4 extends at least partially into the clearance cavity 31. The Hall chip 4 can be a Hall chip 4 used in conventional Hall current sensors. The Hall chip 4 can be located in the middle of the clearance cavity 31, that is, it can be located in the middle of the air gap 2 along the width direction, or it can have a certain deviation; regardless of whether there is a positional deviation, the current detection output result of the calibrated Hall sensor can be made accurate in the subsequent calibration process.

[0041] Please refer to Figure 1 The PCB board 5 is mounted on the housing 3, and the Hall chip 4 is mounted on the PCB board 5. The PCB board 5 can be a circuit board used for conventional Hall current sensors, and the Hall chip 4 is fixed on the PCB board 5.

[0042] Please refer to Figure 1In this application, the two C-shaped magnetic cores 1 and the housing 3 are directly fixed by integral molding, which avoids the increase in volume caused by the use of bolts or clips for assembly, and also avoids the accuracy problem during assembly. The two C-shaped magnetic cores 1 in this solution adopt a double air gap structure, which can increase the conduction and dispersion effect of magnetic flux, so that the magnetic core needs a higher magnetic field strength to reach the saturation state, thus leading to the delay of magnetic saturation.

[0043] Please refer to Figure 1 The Hall sensor uses only one Hall chip 4, which can sense the circuit located in the detection cavity 32 within the two magnetic cores to achieve the purpose of current detection. Compared with installing Hall chips 4 at each air gap 2, this solution reduces material costs and installation difficulty, and helps to further reduce the size of the sensor.

[0044] Please refer to Figure 1 When the measured current flows through the conductor passing through the center of the C-type magnetic core 1, according to Ampere's circuital law, the current will generate a closed magnetic field in the magnetic core. The double air gap design between the C-type magnetic cores 1 divides the magnetic field into two symmetrical paths. The magnetic field strength forms a superposition effect in the double air gap region, while extending the effective length of the magnetic circuit and delaying the saturation of the magnetic core.

[0045] Please refer to Figure 1 In some examples, the C-shaped magnetic core 1 includes a main body 11, a short bend 12, and a long bend 13. The short bend 12 and the long bend 13 are located on the same side of the main body 11, and the length of the long bend 13 is greater than the length of the short bend 12. This structure allows the C-shaped magnetic core 1 to be oriented in both directions, facilitating positioning during installation. Simultaneously, this structure enables the current between two C-shaped magnetic cores 1 to generate the desired magnetic field effect at the air gap 2.

[0046] In some examples, the main body 11, the short bend 12, and the long bend 13 can be integrally formed or formed by other forming methods, such as cutting; the cross-sections of the main body 11, the short bend 12, and the long bend 13 can be exactly the same, and the connection between the main body 11 and the short bend 12 or the long bend 13 can be rounded.

[0047] Please refer to Figure 1 In some examples, the two air gaps 2 include a main air gap 21 and a secondary air gap 22. The main air gap 21 is formed between the two short bends 12 of the two C-shaped magnetic cores 1, and the secondary air gap 22 is formed between the two long bends 13 of the two C-shaped magnetic cores 1. The detection cavity 32 is located at the main air gap 21.

[0048] The main air gap 21 is used to install the Hall chip 4. Its large gap facilitates the installation and positioning of the Hall chip 4. The secondary air gap 22 can limit the outflow of magnetic flux to a certain extent, thereby enhancing the sensor's ability to resist external interference. At the same time, it can also utilize the characteristics of magnetic flux change brought about by the dual air gaps to make it more difficult for the magnetic core to reach magnetic saturation, thereby delaying the occurrence of magnetic saturation.

[0049] In some examples, the width of the main air gap 21 between the ends of the two short bends 12 of the two C-shaped magnetic cores 1 can be greater than or equal to 3 mm.

[0050] The width of the secondary air gap 22 between the ends of the two long bends 13 of the two C-shaped magnetic cores 1 can be between 1 mm and 3 mm.

[0051] Please refer to Figure 1 In some examples, a receiving groove 33 is formed on the housing 3, which is used to mount the PCB board 5 and is connected to the clearance cavity 31. The receiving groove 33 facilitates the installation and fixation of the PCB board 5.

[0052] In some examples, the receiving groove 33 may be flat and one end of the receiving groove 33 may extend through the housing 3 to facilitate the installation, fixation and configuration of the PCB board 5.

[0053] Please refer to Figure 2 In some examples, two C-shaped magnetic cores 1 and one Hall chip 4 form a detection unit 6. Three detection units 6 are configured, spaced apart along the distribution direction of the two C-shaped magnetic cores 1. The three Hall chips 4 of the three detection units 6 are mounted on the same PCB board 5. The three detection units 6 can each carry three different currents, thus broadening the applicability of the Hall sensor; for example, it can directly detect three-phase electricity.

[0054] Please refer to Figure 2 For example, one detection unit 6 can be used to detect one line, that is, each detection unit 6 can be used independently to achieve basic current detection requirements.

[0055] Please refer to Figure 2 Furthermore, the three detection units 6 can be used independently or simultaneously. For example, when testing a three-phase circuit, the three lines of the three-phase circuit can be installed in the three detection cavities 32 of the three detection units 6 respectively, so that the integrated three detection units 6 can be directly used to test the three-phase circuit.

[0056] However, this structure is not only used for detecting three-phase circuits, but also for detecting two-line or multi-line parallel circuits, and can also serve the corresponding current detection purpose.

[0057] Please refer to Figure 2 In some examples, the gaps between any two adjacent detection units 6 are equal. Equal gaps between adjacent detection units 6 allow for a more regular and rational layout of all C-type magnetic cores 1, contributing to improved consistency of current detection results.

[0058] In some other examples, the gap between two adjacent detection units 6 may also be unequal.

[0059] Please refer to Figure 2 In some examples, all C-type magnetic cores 1 of the three detection units 6 are integrated into the same housing 3. All C-type magnetic cores 1 are simultaneously housed in the housing 3 in a single integral molding process, which reduces manufacturing complexity and improves the positional accuracy of the C-type magnetic cores 1.

[0060] Please refer to Figure 2 In some examples, three detection units 6 form a three-phase detection assembly 7. The three-phase detection assembly 7 is configured in two groups, with the two groups of three-phase detection assemblies 6 spaced apart along the distribution direction of any two C-shaped magnetic cores 1. The two groups of three-phase detection assemblies 7 can simultaneously detect the same three-phase circuit. Therefore, if one group of three-phase detection assemblies 7 fails, the circuit can be directly tested through the other group of three-phase detection assemblies 7, which helps to improve the fault tolerance of the equipment and reduce the repair and replacement rate.

[0061] In some examples, the two three-phase detection components 7 can be designated as primary and secondary, with the primary component 7 used in daily operation and the secondary component 7 used as a backup. This backup design is a common design for Hall current sensors and will not be elaborated further here.

[0062] Please refer to Figure 2 In some examples, the dual-gap Hall sensor also includes a communication terminal 8, which is soldered onto the PCB board 5. Please refer to [reference needed]. Figure 3 One end of the communication terminal 8 extends outside the housing 3. The communication terminal 8 facilitates the connection between the circuitry on the PCB board 5 and the outside world.

[0063] In some examples, the way communication terminal 8 is connected to PCB board 5 to transmit current and signals is a common configuration method, which will not be described in detail here.

[0064] In some examples, the Hall chip 4 can be precisely mounted on the PCB board 5, with its Hall sensing unit aligned with the midpoint of the air gap 2 of one of the two C-shaped magnetic cores 1. The Hall chip 4 senses the combined magnetic field strength at the air gap 2 and outputs a voltage signal proportional to the magnetic field strength based on the Hall effect. This voltage signal is output to an external system through circuitry on the PCB board 5 and a pin header communication terminal 8, which simultaneously provides power to the sensor and a ground connection.

[0065] Please refer to Figure 2 and Figure 3 In some examples, the dual-gap Hall sensor may also include an encapsulation layer 9. Since multiple recessed areas are formed on the housing, the encapsulation layer 9 can encapsulate other recessed areas besides the detection cavity 32, thereby improving the protection capability of the dual-gap Hall sensor.

[0066] Encapsulation layer 9 can be made of epoxy resin material, and the following functions can be achieved through vacuum potting process:

[0067] Mechanical reinforcement: fill the gap between the cavity inside the housing 3 and the PCB board 5 to eliminate internal mechanical stress.

[0068] Environmental protection: Forms an IP67-rated sealed barrier to resist humidity, dust and chemical corrosion.

[0069] Please refer to Figure 2 and Figure 3 In some examples, a fixing post can be installed on the outside of the housing 3. The welded fixing post can firmly connect the finished dual-gap Hall sensor to the external device, ensuring the stability of the sensor in a vibration environment. The encapsulation layer 9 completely fills the internal gaps of the housing assembly, forming a moisture-proof, dust-proof, and chemical corrosion-resistant sealed barrier, while alleviating the mechanical stress of the internal components caused by temperature changes.

[0070] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0071] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A dual air gap Hall sensor characterized in that, include: Two C-type magnetic cores are provided, with their ends facing each other to form two air gaps between them. The housing is integrally formed outside the two C-shaped magnetic cores. A clearance cavity is formed on the housing corresponding to one of the air gaps. A detection cavity is formed on the housing in the middle of the two C-shaped magnetic cores. The opening direction of the detection cavity is perpendicular to the distribution direction of the two C-shaped magnetic cores and the distribution direction of the two air gaps. The Hall chip extends at least partially into the recess cavity; A PCB board is disposed on the housing, and the Hall chip is disposed on the PCB board.

2. The dual-air-gap Hall sensor according to claim 1, characterized in that, The C-shaped magnetic core includes a main body, a short bend, and a long bend. The short bend and the long bend are located on the same side of the main body, and the length of the long bend is greater than the length of the short bend.

3. The dual-air-gap Hall sensor according to claim 2, characterized in that, The two air gaps include a main air gap and a secondary air gap. The main air gap is formed between the two short bends of the two C-shaped magnetic cores, and the secondary air gap is formed between the two long bends of the two C-shaped magnetic cores. The detection chamber is located in the main air gap.

4. The dual-air-gap Hall sensor according to any one of claims 1 to 3, characterized in that, A receiving groove is formed on the housing, the receiving groove is used to install the PCB board, and the receiving groove is in communication with the clearance cavity.

5. The dual-air-gap Hall sensor according to claim 4, characterized in that, Two C-shaped magnetic cores and one Hall chip constitute a detection unit. There are three detection units, which are spaced apart along the distribution direction of the two C-shaped magnetic cores. The three Hall chips of the three detection units are disposed on the same PCB board.

6. The dual-air-gap Hall sensor according to claim 5, characterized in that, The gaps between any two adjacent detection units among the three detection units are equal.

7. The dual-air-gap Hall sensor according to claim 6, characterized in that, All the C-type magnetic cores of the three detection units are integrated in the same housing.

8. The dual-air-gap Hall sensor according to claim 5, characterized in that, The three detection units constitute a three-phase detection assembly, which is set in two groups, with the two three-phase detection assemblies spaced apart along the distribution direction of any two C-shaped magnetic cores.

9. The dual-air-gap Hall sensor according to claim 1, characterized in that, The dual-gap Hall sensor also includes a communication terminal, which is soldered to the PCB board and one end of the communication terminal extends outside the housing.

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