Shunt comprising regions with different densities

Abstract

The invention relates to a shunt for measuring an electric current. The shunt has an input region (1) with at least one input contact (4), and the shunt has an output region (3) with at least one output contact (5), wherein the shunt has at least one measuring section (2) which is arranged between the input region (1) and the output region (3). The invention is characterized in that the input region (1), the measuring section (2), and the output region (3) have the same material, and the measuring section (2) has a lower density than the input region (1) and the output region (3).

Description

[0001] Shunt with areas of different density

[0002] The invention relates to a shunt for measuring electrical current, wherein the shunt has an input region with at least one input contact and the shunt has an output region with at least one output contact, and wherein the shunt has at least one measuring section which is arranged between the input region and the output region.

[0003] The invention also relates to a method for measuring an electric current with a shunt and to a current measuring device with a shunt.

[0004] A shunt, also called a shunt resistor or current measuring resistor, is an electrical component used to measure electrical currents, especially larger currents such as those in the range of over 100 amperes. The current to be measured is passed through the shunt. A measuring section of the shunt has a defined resistance, and by measuring the voltage drop along this measuring section, the current strength can be determined. For this purpose, the measuring section is usually made of a material with a higher resistance than the input and output sections, which should generally have the lowest possible resistance to keep heat generation to a minimum.

[0005] US 3273027 A discloses a device comprising a section consisting of a hollow cylinder, the cylinder being filled with a different material than its shell. This structure is complex and expensive to manufacture.

[0006] Smaller shunts for low currents sometimes have measuring sections made of the same material as the input and output sections. However, this is no longer possible for high currents due to the heat generation and losses at the input and output sections.

[0007] The object of the invention is therefore to provide a shunt, a current measuring device and a method as mentioned above, which can be manufactured as simply as possible and yet is as stable as possible and is suitable for measuring larger currents.

[0008] This object is achieved according to the invention in that the input region, the measuring section, and the output region are made of the same material, and the measuring section has a different density than the input region and the output region. It is also achieved in that the method comprises the following steps:

[0009] Providing at least one shunt according to the invention or one current measuring device according to the invention;

[0010] Conducting the current to be determined through the measuring section of the shunt, which has a different density than the input and output areas;

[0011] Measurement of the voltage drop along the measuring section; and

[0012] Calculation of the current to be determined taking into account the voltage drop along the measuring section and the resistance of the measuring section.

[0013] The process steps can sometimes be performed simultaneously or in a different order. Steps can also be performed in between, before, or after.

[0014] The electrical resistance of the test section is usually known very precisely. Thus, using Ohm's law, the current flowing can be determined by measuring the voltage drop along the test section. The current to be determined can be calculated using the formula I = U / R, where I is the current to be determined, U is the measured voltage drop, and R is the electrical resistance of the test section.

[0015] Density matching makes it particularly easy to precisely adjust the electrical resistance of the measuring section, regardless of the cross-sections or lengths of these components. This allows the electrical resistance to be adjusted independently of the resistances of the input and output sections, without the need to change the material. For the production of shunts with different densities in the measuring section, only minor adjustments to the manufacturing process are required. This makes manufacturing easier.

[0016] Furthermore, the solution according to the invention made of a single material can prevent undesirable interactions between different materials at interfaces.

[0017] It is particularly advantageous if the measuring section has a lower density than the input and output regions. The lower density of the measuring section results in a higher electrical resistance of the measuring section than that of the output or input regions. This ensures that the input and output regions have low thermal loads and low voltage drops, yet the measuring section can still be constructed from the same material. Furthermore, the thermal load on the measuring section itself is lower because its surface area is larger. This requires a design that is easy to manufacture, yet still has low thermal losses and is suitable for measuring high currents.

[0018] "Arranged between the input and output areas" means that the measuring section is electrically connected between the input and output areas. The current to be measured therefore flows from the input area through the measuring section to the output area. This generally means that the measuring section is also spatially located between the input and output areas. However, curved or arched designs are also conceivable, for example, in which the measuring section is electrically connected between the input and output areas, but not spatially located between them.

[0019] Preferably, the density of the measuring section is substantially uniform along the measuring section. This improves the measurement result because uneven heating and thus resistance changes of the measuring section are prevented.

[0020] It is essential that this is not a mere reduction in the cross-section of the measuring section; rather, the density of the material from which the measuring section is made must be lower. This can be achieved, for example, through porosity or through internal cavities, which preferably have an average diameter of less than 0.5 mm. These pores or cavities can be filled with air or another gas, or with another material, preferably an electrically insulating and / or thermally conductive material.

[0021] Preferably, the measuring section has a porosity that is higher than the porosity of the inlet and outlet regions. If the measuring section contains cavities, this reduces the density of the measuring section without the material of the measuring section having to be changed. The cavities can be closed off, for example by forming bubbles. The measuring section can therefore be closed-pored. The cavities can also be connected to one another, meaning the measuring section can be open-pored. It can also be useful for the measuring section to have a porosity that is lower than or essentially the same as the porosity of the inlet and outlet regions. The pores preferably have an average diameter of no more than 0.5 mm.

[0022] Furthermore, it can be advantageous if at least the measuring section, and preferably also the input and output sections, are additively manufactured components. Using additive manufacturing, such as 3D printing, the density can be easily adjusted, and the measuring section can also be manufactured together with at least the input and / or output sections. This allows even more complex shapes of the measuring section and / or the shunt to be manufactured more easily.

[0023] Preferably, the cross-sectional area of ​​the measuring section and the cross-sectional areas of the input and output sections in the area of ​​connection to the measuring section are essentially the same size. This allows for a uniform shape and simple manufacturing of the components. Furthermore, this ensures that the surface area of ​​the measuring section is large enough to dissipate the generated heat.

[0024] It can also be provided that the shunt has at least one measuring contact, preferably at least two measuring contacts. To enable simple measurement of the voltage drop along the measuring section, it is advantageous if both the input region and the output region each have at least one measuring contact. It can also be provided that the measuring section has at least one measuring contact, wherein the at least one measuring contact is preferably arranged at an edge region of the measuring section relative to the input region and / or the output region.

[0025] The invention also relates to a current measuring device with a shunt for the current to be determined to flow through, wherein the shunt is designed according to the invention, and wherein the current measuring device has a voltmeter for measuring the voltage drop along the measuring path, which is electrically connected to measuring contacts of the shunt. The current measuring device has an evaluation unit for calculating the current flowing through the shunt, and the evaluation unit is connected to the first voltmeter. This connection between the voltmeter and the evaluation unit is designed to transmit measurement data from the voltmeter to the evaluation unit.

[0026] The invention will be explained in more detail below with reference to the non-limiting embodiment shown in the figure. The figure shows an embodiment of a shunt according to the invention as part of a current measuring device according to the invention.

[0027] The embodiment shown comprises an input region 1, an output region 3, and a measuring section 2 electrically connected and arranged between them. The input region 1 has an input contact 4 on the side facing away from the measuring section 2, which can be connected to an interface and through which the current to be determined can be introduced. The output region 3 has an output contact 5 on the side facing away from the measuring section 2, which can be connected to an interface and through which the current to be determined can be discharged.

[0028] The input area 1 and the output area 3 each have a measuring contact 6 via which the voltage drop on the measuring section 2 can be measured.

[0029] The measuring section 2 is made of the same material as the entrance area

[0030] 1 and the output area 3, these elements are also connected to each other in one piece.

[0031] The measuring section 2 is porous, while the inlet area 1 and / or the outlet area 3 are solid, i.e. non-porous. Thus, the density of the measuring section

[0032] 2 in this embodiment is lower than the density of the input region 1 and the output region 3, and the electrical resistance of the measuring section 2 is higher. In alternative embodiments, the measuring section 2 can be solid, i.e., non-porous, while the input region 1 and / or the output region 3 are porous, resulting in a greater density of the measuring section 2 than the density of the input region 1 and the output region 3.

[0033] Measuring section 2 has essentially the same cross-section as the input section 1 and the output section 3 in the area where it connects to measuring section 2. It only has two lateral notches 2a centrally between input section 1 and output section 3. This partial reduction in cross-section increases the electrical resistance. The resistance can be adjusted by adjusting the size of the notches.

[0034] In addition to the shunt, the current measuring device also includes a voltmeter 14, which is electrically connected to the measuring contacts 6. The voltmeter 14 is further connected to an evaluation unit 13 and configured to transmit data concerning the measured voltage drop to the evaluation unit 13. This can be achieved via data lines, radio, or other connection types. The evaluation unit 13 can calculate the current to be determined based on this data.

Claims

PATENT CLAIMS 1. Shunt for measuring electrical current, wherein the shunt has an input area (1) with at least one input contact (4) and the shunt has an output region (3) with at least one output contact (5), and wherein the shunt has at least one measuring section (2) which is arranged between the input region (1) and the output region (3), characterized in that the input region (1), the measuring section (2) and the output region (3) have the same material and the measuring section (2) has a different density than the input region (1) and the output region (3).

2. Shunt according to claim 1, characterized in that the measuring section (2) has a lower density than the input region (1) and the output region (3).

3. Shunt according to claim 1 or 2, characterized in that the measuring section (2) has a porosity which is higher than the porosity of the input region (1) and the output region (3).

4. Shunt according to claim 1 or 2, characterized in that the measuring section (2) has a porosity which is lower than the porosity of the input region (1) and the output region (3).

5. Shunt according to one of claims 1 to 4, characterized in that at least the measuring section (2), preferably also the input region (1) and the output region (3), are manufactured additively.

6. Shunt according to one of claims 1 to 5, characterized in that a cross-sectional area of ​​the measuring section (2) and cross-sectional areas of the input region (1) and the output region (3) in the region of the connection to the measuring section (2) have substantially the same sizes.

7. Shunt according to one of claims 1 to 6, characterized in that both the input area (1) and the output area (3) each have at least one measuring contact (6).

8. Shunt according to one of claims 1 to 7, characterized in that the density of the measuring section (2) along the measuring section (2) is substantially uniform.

9. Current measuring device with a shunt for the current to be determined to flow through, wherein the shunt is designed according to one of the preceding claims, and wherein the current measuring device has a voltmeter (14) for measuring the voltage drop along the measuring section (6), which is electrically connected to measuring contacts (6) of the shunt and the current measuring device has an evaluation unit (13) for calculating the current flowing through the shunt (1), and that the evaluation unit (13) is connected to the first voltmeter (14).

10. A method for measuring an electric current with a shunt, comprising the following steps: Providing at least one shunt according to one of claims 1 to 8 or a current measuring device according to claim 9; Conducting the current to be determined through the measuring section of the shunt, which has a different density than the input area (1) and the output area (3); Measuring the voltage drop along the measuring section (2); and Calculation of the current to be determined taking into account the voltage drop along the measuring section (3) and the resistance of the measuring section (2).

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