TWM645896U - Electric tool and electronic clutch thereof - Google Patents

Abstract

An electronic clutch for an electric tool includes a base plate, an adjustment device, and a controller. The substrate includes an arc-shaped variable resistance area. The variable resistance area has a resistance section and a functional section. The resistance coefficient of the functional section is lower than that of the resistance section. The adjusting device can be operated to change the position of an electrical connection member in contact with the variable resistance area and output an output signal. The controller determines the position where the electrical connector contacts the variable resistance area based on the output signal and a resistance data, and outputs a function or rotation speed corresponding to the contact position when it determines that the functional segment or the resistance segment is contacted. control signal. In this way, the effect of switching different rotation speeds and different functions can be achieved just by operating the adjustment device, which is very convenient in operation.

Description

Electric tools and their electronic clutches

The present invention relates to a tool and a clutch used by the tool, in particular to an electric tool and an electronic clutch used by the electric tool.

Conventional power tools achieve the purpose of adjusting the torque output by changing the spring force of the compression spring. However, this kind of mechanical structure makes the assembly of parts complex and increases the cost.

In order to solve the above problems, electronic clutches have been developed for control. The electronic clutch uses an electronic circuit to output a feedback signal to the controller, and then adjusts the motor output (torque and speed) through the controller. This can reduce many mechanical structures and achieve Reduce costs and reduce weight. As shown in Chinese Utility Model Patent Announcement No. CN 202779907, it is an electric tool using an electronic clutch. However, because its structure is: setting multiple parallel resistors on the circuit board, and using a contact brush to switch to select the electrically connected Resistors have a large number of electronic components, require a lot of manufacturing processes, and are expensive. Moreover, when you want to switch other functions (such as drilling or hammering), you still need to operate another switch to switch. Use the following Still not convenient enough.

Therefore, the purpose of the present invention is to provide an electronic clutch for electric tools that can solve the above problems.

Therefore, the electronic clutch of the new electric tool includes a substrate, an adjustment device, and a controller.

The substrate includes an arc-shaped variable resistance area. The variable resistance area has a resistance section and a functional section connected to the resistance section. The resistance coefficient of the functional section is lower than that of the resistance section.

The adjustment device includes an electrical connector contacting the variable resistance area. The electrical connector can be driven to change the position of contact with the variable resistance area and output an output signal related to the resistance of the contacted position.

The controller is electrically connected to the electrical connector, determines the position where the electrical connector contacts the variable resistance area based on the output signal and a resistance data, and outputs a control function corresponding to the contact position when determining contact with the functional segment. signal, when it is determined that the resistance segment is contacted, the control signal corresponding to the rotation speed of the contact position is output.

Therefore, the purpose of the present invention is to provide an electric tool that can solve the above problems.

Therefore, the new electric tool includes a drive unit and the above-mentioned electronic clutch.

The driving unit includes a motor for providing operating power, and the driving unit receives a control signal to adjust the rotation speed of the motor.

The function of the present invention is that by dividing the variable resistor into the resistance segment and the functional segment, and setting the electrical connector for switching, the electrical connector can be driven to change the contact with the variable resistor only by operating the adjustment device. The position of the variable resistance area can achieve the effect of switching different speeds and different functions, which is very convenient in operation.

Referring to Figures 1 and 2, an embodiment of the new electric tool includes a frame 1, a power supply unit 2, a drive unit 3, a detection unit 4, a control unit 5, and an electronic clutch 6.

The frame 1 is used to install the power supply unit 2 and the electronic clutch 6, and accommodate the drive unit 3, the detection unit 4 and the control unit 5.

The power unit 2 includes a battery 21 and a power circuit 22 . The power circuit 22 provides the power supply (for example, DC 18V) provided by the battery 21 to the internal circuit after voltage stabilization and voltage transformation. The power circuit 22 may include, for example, two low-dropout voltage regulators that provide different voltages. 221 (Low-dropout regulator, abbreviated as LDO) to supply power to the control unit 5 and a driving circuit 32 respectively.

The driving unit 3 includes a motor 31 , the driving circuit 32 and a switch circuit 33 . The motor 31 is used to provide operating power and is controlled to operate at different speeds. The motor 31 is, for example, a brushless DC motor (BLDC). The drive circuit 32 receives a control signal (PWM signal) output by the control unit 5, and controls the switch circuit 33 to drive the motor 31 to rotate at a target speed according to the duty ratio of the PWM signal. The switching circuit 33 may be implemented using a semiconductor (MOSFET) switch, for example.

The detection unit 4 includes a motor current detection circuit 41 , a battery voltage detection circuit 42 and a trigger switch detection circuit 43 . The motor current detection circuit 41 is used to detect the current of the motor 31 for the control unit 5 to monitor the current of the motor 31 . For example, when the current is too large, the drive circuit 32 can be controlled to stop the operation of the motor 31 to achieve an overcurrent protection effect. The battery voltage detection circuit 42 is connected between the battery 21 and the control unit 5 for detecting the voltage of the battery 21 so that the control unit 5 adjusts the PWM output to the driving circuit 32 according to the voltage of the battery 21 The duty cycle of the signal is adjusted to maintain the motor 31 operating at the target speed. The trigger switch detection circuit 43 is used to detect whether the user presses a trigger 11 and output it to the control unit 5 .

Since those with ordinary knowledge in the art can deduce the extended details of the above architecture based on the above description, no further description will be given.

The control unit 5 is used to control the driving circuit 32 to drive the motor 31 to operate. The control unit 5 can be designed as a circuit with functions such as A/D conversion, I/O detection, communication transmission, PWM output, etc., for example, it can be implemented using a microcontroller (Microcontroller, abbreviated as MCU).

Referring to Figures 3, 4 and 5, the electronic clutch 6 includes a base plate 61, an adjustment device 62 and a controller. In this embodiment, the controller is integrated into the control unit 5, so it is referred to as the control unit 5 below. However, in practical applications, the controller can also be designed as an electronic component or circuit independent of the control unit 5 according to requirements.

The base plate 61 is disposed corresponding to the adjusting device 62 and has an arc shape. In this embodiment, the base plate 61 is disposed nearby on the shell of a deceleration device 91, but it can also be disposed adjacent to the adjusting device 62. The location is not limited to this. The substrate 61 can be implemented using a printed circuit board (PCB), with an arc-shaped variable resistance region 611 and a conductive region 616 provided on its surface. An axis L passing through the center of the arc-shaped variable resistance region 611 is defined.

Both ends of the variable resistance region 611 are electrically connected to different potentials, for example, one end is electrically connected to the positive potential terminal (VCC), and the other end is electrically connected to the ground terminal (GND). The variable resistance area 611 has an arc-shaped resistance section 612, and a functional section 613 connected to the resistance section 612 and extending continuously in an arc shape, and optionally also has a functional section 613 connected to the resistance section 612 opposite to the function. A buffer section 614 at one end of the section 613, and two connecting sections 615 located at both ends of the variable resistance area 611.

The resistance section 612 must be made of a material with a large resistance coefficient so that the resistance value of each contact position can be easily distinguished. For example, a carbon film resistor can be used. The functional section 613 can be made of a material with a low resistance coefficient, so that the potential difference of the entire functional section 613 is small, thereby reducing the occupied voltage range and increasing the usable voltage range of the resistive section 612, thereby increasing the The resolution between contact locations. The buffer section 614 can also be made of a material with a low resistivity, so that the potential difference of the entire section of the buffer section 614 is small. In this way, the potential area at the end of the resistance section 612 can be extended to increase the allowable tolerance during component assembly. The functional section 613 and the buffer section 614 can be made of a material with a low resistivity, such as silver or copper. Among them, the resistor section 612, the functional section 613 and the buffer section 614 are arranged in descending order in order of extension length.

The connecting sections 615 are used as electrical connections, and their material can be made of copper. At least one via hole (VIA) can be provided for signal wiring through the space on the back of the substrate 61 . As shown in Figure 4, since the connection sections 615 will be connected to the positive potential terminal (VCC) and the ground terminal (GND) respectively, for the sake of clarity, the via holes are directly labeled as VCC according to the potential. ,GND. Each of the connecting sections 615 is provided with a via hole VCC and GND, and then connected to the corresponding two via holes VCC and GND at the bottom of Figure 4 through the signal line on the back of the substrate 61, and then connected externally to obtain power.

The conductive area 616 is electrically connected to the control unit 5 and is arc-shaped. It can surround the periphery of the variable resistance area 611 or be adjacent to the inner periphery of the variable resistance area 611 . The conductive area 616 and the variable resistance area 611 are concentrically arranged and coincide with each other in the circumferential direction. The conductive region 616 is made of a material with a low resistivity so that the entire conductive region 616 has substantially the same potential. For example, it can be made of copper. Similarly, the conductive area 616 is also connected to another conductive hole 618 at the bottom of FIG. 4 through a signal line on the back of the substrate 61 through a conductive hole 617 , and then output to the control unit 5 .

Referring to Figures 4 and 6, it is worth noting that the substrate 61 can also be annular as shown in Figure 6. In this way, the variable resistance region 611 with a longer length can be provided, which can easily distinguish more number of segments. For example, in Figure 4, 11 segments such as S1~S11 are configured together, while in Figure 6, 14 segments such as S1~S14 are configured together. However, if the resolution of the subsequent control unit 5 is sufficient, a shorter length can also be matched with a higher number of segments, and is not limited to this. In FIG. 6 , the conductive area 616 can be arranged in a concentric ring or arc shape in conjunction with the variable resistance area 611 .

Refer to Figure 6 and Table 1 below. Table 1 shows an example of resistance data. The resistance data is the preset voltage range corresponding to each function and number of stages. Different numbers of stages correspond to different motors 31 (see Figure 2 ) speed, and different numbers of stages can also be used to set different overcurrent protection values. As shown in FIG. 6 , the resistor section 612 basically corresponds to the function of a screwdriver (in FIG. 6 , the buffer section 614 is regarded as the potential extension of the end of the resistor section 612 ), and is marked with S in the figure. In this embodiment, the resistance data has 14 segments, that is, the resistance segment 612 is divided into 14 segments, and each segment corresponds to segment numbers 1 to 14 (S1 to S14) respectively. In FIG. 6 , S1 and S14 respectively mark the position of the first and last segments of the resistor segment 612 as an illustration. The function section 613 corresponds to the drilling and hammering functions, which are marked D and H respectively in the figure. It is worth noting that since the number of segments is set based on the pre-stored resistance data, when the number of segments needs to be changed, only the resistance data needs to be updated (no need to change the settings of the resistance segments 612 or the substrate 61) , the number of segments corresponding to the resistance segment 612 can be changed. Function Voltage range(V) Output voltage example (V) Screwdriver (S1~S14) Number of segments 1 0~0.15 0.005 2 0.16~0.45 0.237 3 0.46~0.75 0.582 4 0.76~1.05 0.902 5 1.06~1.45 1.243 6 1.46~1.75 1.603 7 1.76~2.15 1.966 8 2.16~2.45 2.308 9 2.46~2.85 2.672 10 2.86~3.15 3.062 11 3.16~3.55 3.411 12 3.56~3.90 3.725 13 3.91~4.20 4.103 14 4.21~4.65 4.419 Drill(D) 4.66~5 4.997 Beat (H) 4.66~5 4.997 Table 1

Referring to Figures 4 and 6, in this embodiment, the connection sections 615 are respectively connected to the positive potential terminal (VCC) and the ground terminal (GND) to provide voltage. Since the connection sections 615 are made of copper, the The functional section 613 and the buffer section 614 are made of silver and occupy a small voltage. The main voltage range will be distributed in the resistor section 612. The voltage of each small section of the resistor section 612 will correspond to Table 1 according to the preset number of sections. The plural voltage ranges in , and the positions (D, H) corresponding to the drilling function and hammering function in the function section 613 also correspond to the preset voltage range in Table 1. It should be noted that since drilling and hammering both correspond to the maximum rotation speed of the motor 31 (see Figure 2), they can share the same voltage range. The difference between drilling and hammering operations is that during the hammering operation, an output shaft (not shown) of the electric tool will reciprocate in the axial direction. This part of the technology is shown in US Patent Nos. US7314097B2, US5505271A, and US10737373B2. I won’t go into details here.

Referring to FIGS. 3 , 4 , 7 and 8 , the adjustment device 62 includes an electrical connector 621 , an adjustment ring 624 and a latch 627 . The adjustment device 62 optionally further includes an auxiliary component 629 .

The electrical connector 621 has a body 622 provided on the adjustment ring 624, and two contact pieces 623 extending from the body 622 at intervals. The contact pieces 623 respectively contact the variable resistance area 611 and the conductive area 616, and output an output signal related to the resistance of the contact position to the control unit 5 through the conductive area 616. The electrical connector 621 is made of conductive material, for example, made of metal springs.

The adjustment ring 624 is arranged around the axis L and can be rotated around the axis L by a user's operation, thereby driving the electrical connector 621 to change the contact position along the arc of the variable resistance region 611 . The adjustment ring 624 has a groove group formed on the inner circumferential surface around the axis L. The groove group is a plurality of grooves 625 positioned corresponding to the engaging member 627 and at least one functional groove 626 . The positions of the segment number grooves 625 correspond to the resistor segments 612 and correspond to the functions of the screwdriver (S). The number of the segment number grooves 625 is the same as the number of segments. For example, in this embodiment, The resistance data is pre-stored with 11 segments, so the segment number grooves 625 need to be set to 11 (S1~S11). When the number of segments needs to be changed, the number of the segment number grooves 625 needs to be changed. The position of the functional groove 626 corresponds to the functional segment 613, and its number is determined according to the number of set additional functions. For example, when only the additional function of drilling (D) is designed (or only the additional function of hammering (H) is set) When the function groove 626 is used, only one functional groove 626 is needed. When the drilling (D) and hammering (H) functions are designed at the same time as in this embodiment, the corresponding drilling (D) and hammering (H) functions are correspondingly provided. ) function of the two functional grooves 626. In FIG. 8 , S, D, and H are also used to mark the positions corresponding to the screwdriver, drilling, and hammering functions, and S1 and S11 are used to mark the positions corresponding to the head and tail segments of the screwdriver function.

The engaging member 627 is disposed corresponding to the adjusting ring 624. In this embodiment, the engaging member 627 is fixedly disposed on a ring member 92 located inside the adjusting ring 624. However, it may also be disposed on another adjacent ring member 92 corresponding to the adjusting ring 624. The position of the adjustment ring 624 is not limited to this. The engaging member 627 is implemented by, for example, an elastic piece having a protruding portion 628 . As the adjustment ring 624 rotates, the convex portion 628 switches to engage with the stage grooves 625 and the functional grooves 626. The engaging member 627 corresponds to the position of the electrical connector 621, so that the engagement When the convex part 628 of the member 627 is engaged with the segmented grooves 625, the electrical connection member 621 is in contact with the resistor segment 612, and when the convex part 628 of the engaging member 627 is engaged with the functional grooves 626 , the electrical connector 621 is in contact with the functional section 613 .

The auxiliary member 629 is disposed at a symmetrical position of the engaging member 627 and is made of the same metal elastic piece as the engaging member 627 . The auxiliary component 629 is used to enhance the stability of the adjustment ring 624 during rotation. In this embodiment, in order to match the auxiliary part 629, a plurality of auxiliary grooves 630 are added to make the grooves inside the adjustment ring 624 symmetrical. If the auxiliary part 629 is not provided, it can be as shown in Figure 9 Only the stage number grooves 625 and the functional grooves 626 are provided.

Referring to FIGS. 3 and 8 , it is worth explaining that in this embodiment, the electrical connector 621 is disposed on the adjustment ring 624 , and the base plate 61 is fixedly disposed inside the electric tool relative to the electrical connector 621 . When the adjustment ring 624 is rotated, the electrical connector 621 is driven to move along the arc of the base plate 61 . However, its installation position can also be reversed. The base plate 61 is placed on the adjustment ring 624, and the electrical connector 621 is fixedly disposed inside the electric tool relative to the base plate 61. In this way, the base plate 61 and the electric connector can still be connected. The effect of relative movement between the connecting parts 621.

Furthermore, in this embodiment, it is explained that the engaging member 627 is fixedly disposed inside the electric tool, and the segmented grooves 625 and the functional grooves 626 are formed in the adjusting ring 624. However, Similarly, the positions of the segmented grooves 625, the functional grooves 626 and the engaging member 627 can also be exchanged, as long as the two can move relative to each other.

Referring to Figures 6 and 9, Figure 9 shows the arrangement of the adjustment ring 624 and the engaging member 627 when used with the annular base plate 61 in Figure 6. In this state, the grooves 625 are The distribution space is relatively large, therefore, only one engaging member 627 is provided without the auxiliary member 629 (see FIG. 8 ).

Referring to Figure 2, Figure 6 and Figure 9, in actual application, the user rotates the adjustment ring 624 to select the required number of stages or functions, so that the engaging member 627 engages in the corresponding groove 625 of the stage or function. The functional groove 626 enables the electrical connector 621 to contact a predetermined position of the resistive section 612 or the functional section 613 . Then, the control unit 5 receives the output signal through the conductive area 616 and performs A/D (Analog to Digital) conversion on the output signal. According to the output signal and the resistance data (Table 1), Determine the position where the electrical connector 621 (see FIG. 3) contacts the variable resistance region 611. When the control unit 5 determines which voltage range in Table 1 the voltage of the output signal is in, the current function and segment number can be correspondingly obtained. When the control unit 5 determines that the functional segment 613 is contacted, it outputs the control signal corresponding to the function (drilling or hammering) of the contact position; when it determines that the resistance segment 612 is contacted, it outputs the rotation speed (segment) of the motor 31 corresponding to the contact position. S1~S14) of this control signal.

Referring to Figure 3 and Figure 4, through the above description, the effects of this embodiment are as follows:

1. By dividing the variable resistance area 611 into the resistance section 612 and the functional section 613, and providing the electrical connector 621 for switching, different rotational speeds can be switched by simply operating the adjustment device 62. , different functions, very convenient to operate. Moreover, compared with the conventional technology, there is no need to additionally weld many resistive components, and the manufacturing process is convenient and the cost is low.

2. Since the control unit 5 (controller) determines the position where the electrical connector 621 contacts the variable resistance area 611 based on the resistance data, when the electric tools with different rotational speeds and different functions are to be used, only It is necessary to adjust the adjustment device 62 accordingly (for example, change the number of the segment grooves 625 and the functional grooves 626), and change the resistance data in the memory of the control unit 5 (controller). The substrate 61 The settings do not need to be changed. That is to say, this embodiment only needs to modify a small part of the program and change a small part of the structure, so it can be applied to the same series of electric tools with different rotation speeds and functions, and has excellent versatility.

3. By arranging the conductive area 616 concentrically with the variable resistance area 611, the electrical connector 621 can contact the variable resistance area 611 and the conductive area 616 at the same time when moving. In this way, the output The signal is transmitted from the variable resistance area 611 to the electrical connector 621 for a short time and then returns to the circuit (the conductive area 616) on the circuit board (the substrate 61). In this way, better signal transmission quality can be achieved.

4. By arranging the buffer section 614, the end potential area of the resistor section 612 can be extended, thereby increasing the allowable tolerance during component assembly while utilizing the complete voltage range.

To sum up, the new electric tool and its electronic clutch can indeed achieve the purpose of the new type.

However, the above are only examples of the present invention, and should not be used to limit the scope of the present invention. All simple equivalent changes and modifications made based on the patent scope of the present invention and the content of the patent specification are still within the scope of the present invention. Within the scope covered by this new patent.

1:Rack 11: Trigger 2:Power supply unit 21:Battery 22:Power circuit 221:Low dropout voltage regulator 3: Drive unit 31: Motor 32: Drive circuit 33: Switch circuit 4:Detection unit 41: Motor current detection circuit 42:Battery voltage detection circuit 43: Trigger switch detection circuit 5:Control unit 6: Electronic clutch 61:Substrate 611: Variable resistance area 612: Resistor section 613: Function segment 614: Buffer segment 615:Connection segment 616: Conductive area 617,618: Via hole 62:Adjustment device 621: Electrical connectors 622:Ontology 623:Contact piece 624:Adjustment ring 625: Segment number groove 626: Functional groove 627:Latching parts 628:convex part 629: Auxiliary parts 630: Auxiliary groove 91: Reduction device 92:Ring piece L: axis D:Drilling function H: Beating function S, S1, S11, S14: Screwdriver function VCC: positive potential end or via hole of positive potential end GND: Ground terminal or via hole of ground terminal

Other features and functions of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: Figure 1 is a schematic diagram of an embodiment of the new electric tool after removing part of the frame; Figure 2 is a circuit schematic diagram of this embodiment; Figure 3 is an incomplete exploded view of this embodiment; Figure 4 is a schematic diagram of a substrate in this embodiment; Figure 5 is a circuit schematic diagram of this embodiment, illustrating the equivalent circuit of an electronic clutch; Figure 6 is a schematic diagram of another aspect of the substrate in this embodiment; Figure 7 is a schematic diagram of this embodiment, illustrating that an electrical connector is disposed on an adjustment ring; Figure 8 is a schematic diagram of this embodiment, illustrating the positional correspondence between a clamping component and a plurality of stages of grooves and a plurality of functional grooves; and FIG. 9 is another schematic diagram of this embodiment, illustrating the appearance of multiple stages of grooves and multiple functional grooves when used with the substrate of FIG. 6 .

61:Substrate

611: Variable resistance area

612: Resistor section

613: Function segment

614: Buffer segment

615:Connection segment

616: Conductive area

617,618: Via hole

D:Drilling function

H: Beating function

S, S1, S11: Screwdriver function

VCC: via hole of positive potential end

GND: Ground via hole

Claims (10)

An electronic clutch for an electric tool, including: A substrate includes an arc-shaped variable resistance area, the variable resistance area has a resistance section, and a functional section connected to the resistance section, and the resistance coefficient of the functional section is lower than that of the resistance section; An adjustment device, including an electrical connector in contact with the variable resistance area, the electrical connector can be driven to change the position of contact with the variable resistance area, and output an output signal related to the resistance of the contacted position; and A controller is electrically connected to the electrical connector, determines the position where the electrical connector contacts the variable resistance area based on the output signal and a resistance data, and outputs a function corresponding to the contact position when determining contact with the functional segment. A control signal, when it is determined that the resistance segment is contacted, the control signal corresponding to the rotation speed of the contact position is output. The electronic clutch of an electric tool as claimed in claim 1, wherein the substrate further includes an arc-shaped or annular conductive area that is electrically connected to the controller. The conductive area is concentrically arranged with the variable resistance area and has a resistance coefficient Below the resistance section, the electrical connection contacts the variable resistance area and the conductive area simultaneously, and outputs the output signal to the controller through the conductive area. The electronic clutch of an electric tool as claimed in claim 1, wherein the adjustment device has an adjustment ring for one of the base plate and the electrical connector to be provided, and the adjustment ring surrounds a center of a circle passing through the variable resistance area. axis, and can rotate around the axis. When the adjustment ring rotates, the corresponding substrate or the electrical connector moves relative to the other, so that the electrical connector moves along the arc of the variable resistance area. Change the contact position. The electronic clutch of an electric tool as claimed in claim 1, wherein the variable resistance area also has a buffer section connected to an end of the resistance section opposite to the functional section, and the resistance coefficient of the buffer section is lower than that of the resistance section. . The electronic clutch of an electric tool as claimed in claim 4, wherein the resistive section, the functional section and the buffer section are arranged in descending order from large to small in extension length. The electronic clutch of the electric tool as claimed in claim 1, wherein the resistance section is a carbon film resistor, and the material of the functional section is silver or copper. A power tool containing: A driving unit, including a motor used to provide operating power, the driving unit receives a control signal to adjust the rotation speed of the motor; and The electronic clutch as described in claim 1. The electric tool according to claim 7, wherein the substrate further includes an arc-shaped or annular conductive area that is electrically connected to the controller. The conductive area is concentrically arranged with the variable resistance area and has a resistance coefficient lower than the The resistance section, the electrical connector contacts the variable resistance area and the conductive area at the same time, and outputs the output signal to the controller through the conductive area. The electric tool according to claim 7, wherein the adjustment device has an adjustment ring for one of the base plate and the electrical connector to be arranged, and the adjustment ring surrounds an axis passing through the center of the variable resistance area, And it can be rotated around the axis. When the adjustment ring rotates, the corresponding substrate or the electrical connector moves relative to the other, so that the electrical connector changes the contact position along the arc of the variable resistance area. . The electric tool as claimed in claim 9, wherein the adjustment ring is provided with one of an engaging member or a groove group, and the groove group is a plurality of grooves whose positions correspond to the engaging member and at least one groove. Functional grooves, the plurality of grooves and the at least one functional groove are arranged around the axis. When the adjustment ring rotates, the relative movement of the engaging member and the groove group is linked, so that the engaging member switches to the latching position. The position of the engaging member corresponds to the position of the electrical connector in relation to the segmented grooves and the at least one functional groove, so that when the engaging member is engaged in the segmented grooves, the electrical connector contacts In the resistor segment, when the engaging member is engaged with the at least one functional groove, the electrical connector contacts the functional segment.