Method for manufacturing a resistor assembly for a sensor device for determining an electric current

Abstract

The invention relates to a method for manufacturing a resistor assembly for a sensor device for determining an electric current, particularly in a vehicle. The resistor assembly comprises an electrical conductor (10) with a measuring section (12), in particular a measuring resistor, and at least two electrical contact elements (20) provided on the electrical conductor (10). The contact elements (20) are designed as press-fit pins (20) that extend into recesses (16) of the electrical conductor (10). The method comprises the following steps: - Providing the electrical conductor (10), - Reducing the material thickness in the area of ​​the recesses (16) for the contact elements (20), - Creating the recesses (16) in the areas (18) with reduced material thickness, - Inserting the contact elements (20) from a first side of the electrical conductor (10) into the recesses (16).

Description

[0001] The invention relates to a method for manufacturing a resistor assembly for a sensor device for determining an electric current.

[0002] Information is a crucial component of modern vehicles. It is used, for example, to regulate control loops, share traffic information with the public, and improve vehicle safety. To obtain this information, the vehicle is equipped with numerous sensors that continuously collect data and transmit it to a control unit for analysis.

[0003] One of the sensors installed in modern vehicles is a battery sensor. This sensor measures the current flowing from the battery. A battery sensor typically consists of an electrical conductor through which the current flows and a current sensor to measure the current. The current sensor can be soldered directly onto the electrical conductor or attached to it using contact elements. If contact elements are used to attach the electrical conductor, they must be welded onto it. This process is expensive and complex, as it requires, for example, cleaning the electrical conductor or reducing the positional accuracy during welding.

[0004] Alternatively, a press-fit connection can be used to attach the current sensor to the electrical conductor. This requires drilling holes in the conductor into which the press-fit pins can be inserted. However, drilling these holes is complex because copper, the material most conductors are made of, is a soft metal compared to others and therefore difficult to work with.

[0005] The invention is based on the objective of providing a method for manufacturing a resistor assembly for a sensor device for determining an electric current, which enables a simple and precise introduction of recesses into the electrical conductor of the resistor assembly.

[0006] To solve the problem, a method for manufacturing a resistor assembly for a sensor device for determining an electric current, particularly in a vehicle, is provided. The resistor assembly comprises an electrical conductor with a measuring section, in particular a measuring resistor, and at least two electrical contact elements provided on the electrical conductor. The contact elements are designed as press-fit pins that extend into recesses in the electrical conductor. The method comprises the following steps: • Providing the electrical conductor, • Reducing the material thickness in the area of ​​the recesses for the contact elements, • Creating the recesses in the areas with reduced material thickness, • Inserting the contact elements from one side of the electrical conductor into the recesses.

[0007] A resistor assembly is defined as an assembly comprising an electrical conductor with a measuring section and two electrical contact elements arranged on the conductor. The resistor assembly conducts an electric current, and due to the physical properties of the measuring section, a defined voltage drop occurs across it. This voltage drop is measured by a sensor device.

[0008] A sensor device is understood to be any device designed to detect an electric current by means of sensor elements included in the sensor device. The sensor device comprises at least one sensor element for detecting the voltage before and / or after the measuring resistor, and a printed circuit board on which the at least one sensor element is arranged. The at least one sensor element is preferably an ASIC.

[0009] An electrical conductor is any device capable of conducting an electric current. The electrical conductor is preferably cuboid in shape. The electrical conductor preferably has two connection sections and a measuring section. The two connection sections and the measuring section are made of two different materials, with the connection sections preferably being made of copper. Alternatively, the two connection sections and the measuring section are made of the same material.

[0010] A measuring section is defined as any section with a fixed geometry, where the geometry and material properties define the electrical resistance value of the measuring section. The measuring section is preferably made of a copper-nickel-manganese alloy that exhibits very low temperature-related deviations in electrical resistance.

[0011] A contact element is understood to be an element that can be arranged on the electrical conductor and is designed for fastening and as an electrical contact for the sensor device. The contact elements are formed on the electrical conductor and are inserted into recesses. The contact element is preferably a press-fit pin or a stud.

[0012] A recess is understood to be an element that extends over the entire height of the electrical conductor and is designed for the arrangement of contact elements. The recess is preferably designed as a hole. The recess is preferably created by punching or drilling.

[0013] The advantage of the proposed invention lies in the simplification of the manufacturing process for the resistor assembly, as the complex process steps of welding the pins onto the electrical conductor, such as cleaning the conductor, preventing contamination during welding, or maintaining pin positional accuracy, are no longer required. This reduces production costs and improves production accuracy.

[0014] Preferably, the reduced material thickness in these areas can be achieved by compression molding. In this process, a press, preferably with a rectangular tool, presses onto the electrical conductor, reducing its thickness in that area. Alternatively, the tool can be round or oval. This has the advantage that, due to the inhomogeneity of the crystal lattice structure and the resulting higher stiffness, the electrical conductor can be processed more effectively in this area when inserting the contact elements, for example, by punching.

[0015] Furthermore, the reduced material thickness in these areas can be achieved through a material removal process. Preferably, the reduced material thickness can be formed by milling. To improve the strength of the material in this area of ​​the electrical conductor, an alloying element can be introduced, for example. This has the advantage that the electrical conductor can be manufactured, for example, in a CNC machine with multiple tools, thus eliminating the need for reclamping in another machine.

[0016] The material thickness can preferably be reduced on the first side of the electrical conductor. The first side of the electrical conductor is preferably the top side, or the side on which the sensor device is to be positioned. This allows the sensor device to be located closer to the resistor assembly. This has the advantage that the current sensor has a reduced height, thus enabling a more compact design.

[0017] Furthermore, the material thickness can be reduced on a second side of the electrical conductor opposite the first. This second side is preferably the underside or the side on which no sensor device is to be placed. This has the advantage that the recesses do not need to be adapted to the size of the press-fit pins.

[0018] Preferably, the area where the material thickness is reduced can extend around the respective recess. This area thus preferably extends across a portion of the width, i.e., perpendicular to the longitudinal direction of the electrical conductor. This has the advantage that smaller tools can be used to reduce the material thickness, and the thickness of the electrical conductor is reduced only in a small area, thereby not significantly altering its current-carrying capacity or mechanical stability.

[0019] The area where the material thickness is reduced preferably extends across the entire width of the electrical conductor. This area of ​​material reduction thus extends across the entire width, i.e., perpendicular to the longitudinal direction of the electrical conductor. This has the advantage that the thickness of the electrical conductor is reduced across its entire width, resulting in higher stiffness due to the inhomogeneity of the crystal lattice structure.

[0020] Furthermore, at least two recesses can be arranged in the area with reduced material thickness. The recesses are arranged one behind the other, essentially perpendicular to the longitudinal direction of the electrical conductor, i.e., across its width. Alternatively, the recesses can be arranged parallel to the longitudinal axis. The at least two recesses for each area with reduced material thickness can be created simultaneously. Alternatively, the recesses for all areas with reduced material thickness can be created simultaneously. Additionally, the recesses in the areas with reduced material thickness can be created sequentially. This has the advantage that multiple contact elements can be arranged in the electrical conductor, enabling an improved arrangement of the sensor device.

[0021] Furthermore, a resistor assembly is claimed as a product of such a method. The resistor assembly comprises an electrical conductor with a measuring section and at least two electrical contact elements provided on the electrical conductor. The contact elements are designed as press-fit pins that extend into recesses in the electrical conductor.

[0022] In addition, a current sensor with a resistor assembly is used.

[0023] Further advantages and features will become apparent from the following description in conjunction with the attached drawings. These show: Fig. 1 an electrical conductor of a resistor assembly with non-continuous material-reduced areas around the recesses; Fig. 2 the electrical conductor to Fig. 1 with continuous material-reduced areas Fig. 3 a sectional view of the electrical conductors according to Fig. 1 and Fig. 2 Fig. 4 A detailed view of the electrical conductor with the material-reduced area and press-fit pin arranged on the top. Fig. 5 A detailed view of the electrical conductor with the material-reduced area on the underside and the press-fit pin arranged on the top. Fig. 6 the electrical conductor with a material-reduced area in a measuring range and a recess

[0024] In Fig. Figure 1 shows an electrical conductor 10 of a resistor assembly. The resistor assembly preferably comprises the electrical conductor 10 with a measuring section 12, at least two contact elements 20 arranged on the electrical conductor, and a sensor device (not shown). Due to its geometry and material properties, the measuring section 12 has a defined electrical resistance.

[0025] The measuring section 12 is arranged between two connection sections 14. A connection section comprises a connection element (not shown) to which, for example, a cable can be attached. The connection elements allow current to flow from a vehicle battery (not shown) via the electrical conductor into the vehicle's electrical system. The connection elements (not shown) could, for example, be drill holes.

[0026] In a connection section 14, two recesses 16 are also arranged. The recesses 16 are arranged essentially perpendicular to the longitudinal direction of the electrical conductor 10. The longitudinal direction extends in the x-direction and the width of the electrical conductor in the y-direction. The recesses 16 are produced, for example, by punching, whereby all recesses 16 are punched simultaneously.

[0027] A material-reduced area 18 is arranged around the recesses 16. This area is preferably rectangular and is arranged around the two recesses 16 located on a connection section 14, wherein in this embodiment the material-reduced area 18 does not extend over the entire width of the electrical conductor 10. The material-reduced area 18 is produced by compression molding, with the molding taking place before the recesses 16 are punched. In another example, the material-reduced area 18 is produced by milling or drilling.

[0028] Contact elements 20, hereinafter also referred to as press-fit pins 20, are inserted into the recesses. These contact elements serve two purposes: firstly, they provide electrical contact between the electrical conductor 10 and a printed circuit board (not shown); and secondly, they secure the printed circuit board (not shown) to the electrical conductor 10. The contact elements 20 comprise a cylindrical carrier body and two pins arranged opposite each other on the carrier body. The two pins preferably differ in diameter. Alternatively, the diameters of the two pins are identical.

[0029] A sensor device (not shown) is arranged on the four contact elements 20 on the electrical conductor 10, the sensor device comprising a printed circuit board and at least one sensor element. The printed circuit board (not shown) has four holes for mounting on the press-fit pins. The printed circuit board is preferably a printed circuit board (PCB).

[0030] At least one sensor element is arranged on the PCB. This sensor element determines the voltage difference via the press-fit pins, which results from the voltage drop across the measuring section 12. Based on the known resistance of the measuring section and the determined voltage difference between the press-fit pins, the current flowing through the electrical conductor 10 can be determined.

[0031] In Fig. 2 is a similar one in Fig. Figure 1 illustrates an electrical conductor 10 of a resistor assembly. The difference lies in the fact that the material-reduced area 18 of the electrical conductor 10 extends over its entire width.

[0032] In Fig. 3 is a sectional view through the in Fig. The electrical conductor 10 shown in Figure 2 is clearly visible. The material-reduced area 18 with the recess 16 is easily recognizable. In the material-reduced area 18, the material in the hatched area 22 preferably exhibits a more inhomogeneous crystal structure. For clarity, further hatching has been omitted from the sectional view. Alternatively, an alloy metal is present in the hatched area 22, which particularly increases the strength in this area. Additionally, the two connection sections are alternatively made of an alloy metal.

[0033] In Fig. Figure 4 shows a detailed view of the material-reduced area 18 of the electrical conductor 10, with a press-fit pin 20 arranged in the recess 16. The material-reduced area 18 is located on the top surface of the electrical conductor 10, i.e., the surface that is higher in the z-direction. This results in a lower overall height of the resistor assembly.

[0034] In Fig. 5 is one to Fig. Figure 4 shows a similar detailed view. In this illustration, however, the material-reduced area 18 is located on the underside of the electrical conductor 10, i.e., the surface lying lower in the z-direction. As a result, the circuit board of the sensor device is positioned slightly higher than in the illustration below. Fig. 4. Example explained.

[0035] The resistor assembly can be manufactured as follows. The electrical conductor 10 with measuring range 12 is placed in a machine tool. The material-reduced area 18 is then created by pressing. The machine tool presses a rectangular body onto an area 18 on the electrical conductor 10, reducing its thickness and increasing its strength due to the change in the crystal lattice structure. Next, the recesses 16 are created. The machine tool simultaneously punches the recesses 16 into the material-reduced area, which has a higher stiffness than copper and is therefore easier to machine. Finally, the press-fit pins 20 are inserted into the recesses. Alternatively, pins can be used that are welded or soldered to the electrical conductor 10.The circuit board is then placed on the press-fit pins 20 and soldered to them.

[0036] Alternatively, the material-reduced area 18 can be produced by milling. In this case, the two connection sections of the resistor assembly comprise an alloy metal that increases the strength in area 18. The previously described steps after pressing are identical here as well.

[0037] In Fig. Figure 6 shows a further embodiment. Here, the measuring range 12 also includes a material-reduced area 18 and a recess 16 formed in this area 18. A press-fit pin 20 is also inserted into this recess 16. This press-fit pin 20 serves to measure the temperature in the measuring range 12. Knowing the temperature of the resistive element allows for more precise temperature compensation, which in turn leads to greater accuracy in determining the electric current. Reference symbol: 10 Electrical conductor 12 Measurement section 14 Connection section 16 cutouts 18 Material-reduced area 20 contact elements 22 hatched area

Claims

[1] Method for manufacturing a resistor assembly for a sensor device for determining an electric current, in particular in a vehicle, wherein the resistor assembly comprises an electrical conductor (10) with a measuring section (12), in particular a measuring resistor, and at least two electrical contact elements (20) provided on the electrical conductor (10), wherein the contact elements (20) are designed as press-fit pins (20) which extend into recesses (16) of the electrical conductor (10), comprising the following steps: - Providing the electrical conductor (10), - Reducing the material thickness in the area of ​​the recesses (16) for the contact elements (20), - Creating the recesses (16) in the areas (18) with reduced material thickness, - Inserting the contact elements (20) from a first side of the electrical conductor (10) into the recesses (16). [2] Method according to claim 1,characterized by , that the reduced material thickness in areas (18) is produced by compression. [3] Method according to claim 1, characterized by , that the reduced material thickness in areas (18) is produced by a material removal process. [4] Method according to any one of the preceding claims, characterized by , that the material thickness on the first side of the electrical conductor (10) is reduced. [5] Method according to any one of the preceding claims, characterized by , that the material thickness is reduced on one of the second sides of the electrical conductor (10) opposite the first side. [6] Method according to any one of the preceding claims, characterized by , that the area (18) in which the material thickness is reduced extends around the respective recess (16). [7] Method according to any one of the preceding claims, characterized by, that the area (18) in which the material thickness is reduced extends over the entire width of the electrical conductor (10). [8] Method according to any one of the preceding claims, characterized by , that in the area (18) with reduced material thickness at least two recesses (16) are arranged. [9] Resistor assembly, wherein the resistor assembly comprises an electrical conductor (10) with a measuring section ( / 12) and at least two electrical contact elements (20) provided on the electrical conductor (10), wherein the contact elements (20) are designed as press-fit pins (20) which extend into recesses (16) of the electrical conductor, wherein areas with reduced material thickness are arranged in the resistor assembly, in particular at the connection sections, wherein recesses are arranged in the areas with reduced material thickness, wherein contact elements are inserted into the recesses, wherein the resistor assembly is manufactured by a method according to one of the preceding claims. [10] Current sensor with resistor assembly according to claim 9, wherein the current sensor comprises a sensor device connected to contact elements and capable of detecting voltages at the contact elements, at least one sensor element capable of detecting a voltage difference between the voltages applied to the contact elements, and a housing made of a polymer that at least partially surrounds the resistor assembly, the sensor device and the at least one sensor element.

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