Current Sensor

Abstract

To fix bus bars and substrates in place by a simple and inexpensive structure.SOLUTION: A fixing part 140 for fixing a substrate 110 to a shunt resistor-integrated bus bar 120 is constituted to have, in each of two bus bar parts of the shunt resistor-integrated bus bar 120, a first section 121 extending in the width direction of the shunt resistor-integrated bus bar 120 and a pair of second sections 142 extending from both ends of the first section 141 toward a shunt resistor section 121 of the shunt resistor-integrated bus bar 120. An electric connection part 130 for electrically connecting a wiring disposed on a substrate 100 and the bus bar section 121 of the shunt resistor-integrated bus bar 120 together is disposed between the pair of second sections 142 of the fixing part 140.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a current sensor. [Background technology]

[0002] A shunt-type current sensor using a shunt resistor-integrated bus bar has been developed (for example, Patent Document 1). As shown in Fig. 2, the shunt resistor-integrated bus bar is a bus bar in which a shunt resistor portion 122 is connected between two bus bar portions 121. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-30154 Summary of the Invention [Problem to be solved by the invention]

[0004] In the shunt-type current sensor disclosed in Patent Document 1, the shunt resistor-integrated bus bar is fixed to the substrate using bolts and nuts, which increases manufacturing costs and complicates assembly.

[0005] Therefore, an object of the present invention is to fix a bus bar and a substrate with a simple and inexpensive structure. [Means for solving the problem]

[0006] In order to solve the above problem, a current sensor according to one embodiment of the present invention comprises a substrate, a shunt resistor-integrated bus bar having two bus bar portions and a shunt resistor portion connected between the two bus bar portions, an electrical connection portion for electrically connecting wiring arranged on the substrate to the bus bar portions, and a fixing portion for fixing the substrate to the shunt resistor-integrated bus bar, wherein when the longitudinal direction of the shunt resistor-integrated bus bar is defined as the X-axis direction and the width direction of the shunt resistor-integrated bus bar is defined as the Y-axis direction, the fixing portion has, in each of the two bus bar portions, a first portion extending in the Y-axis direction and a pair of second portions extending from both ends of the first portion in the Y-axis direction toward the shunt resistor portion, and the electrical connection portion is disposed between the pair of second portions. [Effects of the Invention]

[0007] According to the present invention, it is possible to fix the bus bar and the substrate with a simple and inexpensive configuration. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a current sensor 100 according to an embodiment of the present invention. [Figure 2] 10 is a diagram showing a shunt resistor integrated bus bar 120. FIG. [Figure 3] 1 is a diagram illustrating an electrical connection portion 130 and a fixing portion 140. FIG. [Figure 4] 10 is a diagram illustrating the positional relationship between the integrated shunt resistor 120, the electrical connection portion 130, and the fixed portion 140. FIG. [Figure 5] 10 is a diagram illustrating the positional relationship between a substrate 110 and a fixing portion 140. FIG. [Figure 6] 10A and 10B are diagrams illustrating another example of the current sensor 100. [Figure 7] 10 is a diagram illustrating an example of the relationship between a through-hole 111 and a fixing portion 140. FIG. [Figure 8] 10 is a diagram illustrating an example of the relationship between a through-hole 111 and a fixing portion 140. FIG. [Figure 9]10A and 10B are diagrams illustrating another example of the current sensor 100. [Figure 10] 10A and 10B are diagrams illustrating another example of the current sensor 100. [Figure 11] 10A and 10B are diagrams illustrating another example of the current sensor 100. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Current sensor 100> 1 is a diagram showing a current sensor 100 according to one embodiment of the present invention. The current sensor 100 includes a substrate 110 and a shunt resistor-integrated bus bar 120. In this embodiment, the longitudinal direction of the shunt resistor-integrated bus bar 120 is defined as the X-axis direction, the width direction of the shunt resistor-integrated bus bar 120 is defined as the Y-axis direction, and the direction perpendicular to the longitudinal and width directions of the shunt resistor-integrated bus bar 120 is defined as the Z-axis direction.

[0010] The substrate 110 is made of, for example, an insulator. Wiring and electronic components are arranged on the substrate 110. The wiring and electronic components may be arranged on both sides of the substrate 110, or may be arranged on only one side of the substrate 110. In FIG. 1, illustration of the electronic components and wiring is omitted.

[0011] 2 is a diagram showing a shunt resistor-integrated bus bar 120. The shunt resistor-integrated bus bar 120 has two bus bar portions 121 and a shunt resistor portion 122. The shunt resistor portion 112 is connected between the two bus bar portions 121. For example, as shown in FIG. 1, the substrate 110 is arranged so as to cover parts of the two bus bar portions 121 and the shunt resistor portion 122. In this embodiment, of the two surfaces of the substrate 110, the surface facing the shunt resistor-integrated bus bar 120 is defined as the lower surface, and the other surface is defined as the upper surface.

[0012] The bus bar portion 121 is made of, for example, an electrical conductor. The shunt resistor portion 122 is a shunt resistor.

[0013] 3, the current sensor 100 further includes an electrical connection portion 130 for electrically connecting the wiring and electronic components arranged on the substrate 110 to the bus bar portion 121 of the shunt resistor-integrated bus bar 120. The electrical connection portion 130 is arranged between the wiring (not shown) arranged on the underside of the substrate 110 and the bus bar portion 121 of the shunt resistor-integrated bus bar 120, and electrically connects the wiring and electronic components arranged on the substrate 110 to the bus bar portion 121 of the shunt resistor-integrated bus bar 120. In the example shown in FIG. 3, there is one electrical connection portion 130 for each bus bar portion 121, but there may be multiple electrical connection portions 130 for each bus bar portion 121.

[0014] As shown in FIG. 3 , the current sensor 100 further includes a fixing portion 140 for fixing the substrate 110 to the shunt resistor-integrated bus bar 120. The fixing portion 140 is disposed between the substrate 110 and the shunt resistor-integrated bus bar 120 (particularly, the bus bar portion 121) and fixes the bus bar portion 121 of the shunt resistor-integrated bus bar 120 to the substrate 110. The fixing portion 140 is made of, for example, solder. In this case, the substrate 110 may have a fixing pattern for bonding the solder constituting the fixing portion 140. The fixing pattern is disposed on the underside of the substrate 110. The fixing pattern of the substrate 110 may then be soldered to the bus bar portion 121 of the shunt resistor-integrated bus bar 120, thereby fixing the shunt resistor-integrated bus bar 120 to the substrate 110.

[0015] 4 is a diagram illustrating the positional relationship between the integrated shunt resistor 120, the electrical connection part 130, and the fixed part 140. The integrated shunt resistor 120 has two bus bars 121, each of which has an electrical connection part 130 and a fixed part 140 disposed thereon.

[0016] As shown in FIG. 4 , the fixing portion 140 includes a first portion 141 and a pair of second portions 142 in each of the two busbar portions 121. As shown in FIG. 4 , the first portion 141 extends in the Y-axis direction. The second portions 142 extend from both ends of the first portion 141 in the Y-axis direction toward the shunt resistor portion 122. For example, as shown in FIG. 4 , the second portions 142 may extend parallel to the X-axis direction. In the example shown in FIG. 4 , the fixing portion 140 is U-shaped in each of the two busbar portions 121. For example, as shown in FIG. 3 , the fixing portion 140 is disposed along the periphery of the area where the substrate 110 and the shunt resistor-integrated busbar 120 overlap. In the examples shown in FIGS. 3 and 4 , the fixing portion 140 is configured as an integrated member in each of the two busbar portions 121, but may be configured as multiple separate portions.

[0017] 4, the electrical connection portion 130 is disposed between the pair of second portions 142 of the fixed portion 140 in each of the two busbar portions 121. In other words, the electrical connection portion 130 is disposed inside an area A surrounded by the fixed portion (i.e., the first portion 141 and the pair of second portions).

[0018] Therefore, in this embodiment, stress is concentrated on the fixing portion 140 arranged to surround the electrical connection portion 130, and almost no stress is applied to the electrical connection portion 130, making it less likely that the electrical connection portion 130 will peel off from the bus bar 110. As a result, in this embodiment, the possibility of an abnormal electrical connection occurring is low. In other words, in this embodiment, it is possible to fix the bus bar and the board with high reliability of conduction between the bus bar and the board without using bolts, nuts, or the like. Therefore, in this embodiment, it is possible to fix the bus bar and the board with a simple and inexpensive configuration.

[0019] Furthermore, in this embodiment, peeling occurs in the fixed portion 140 before the electrical connection portion 130. That is, in this embodiment, peeling occurs in the fixed portion 140 before a connection failure occurs in the electrical connection portion 130. Therefore, in this embodiment, by measuring the contact resistance between the fixed portion 140 and the busbar 110, it is possible to detect an abnormality in the current sensor 100 before a connection failure occurs in the electrical connection portion 130.

[0020] Increasing the contact area between the fixed portion 140 and the busbar 120 further distributes the stress acting on the fixed portion 140. Therefore, it is preferable to set the difference between the length L1 of the busbar portion 121 of the shunt resistor-integrated busbar 120 in the Y-axis direction (i.e., the width of the busbar portion 121 of the shunt resistor-integrated busbar 120) and the length L2 of the fixed portion 140 in the Y-axis direction to a first distance or less. This increases the contact area between the fixed portion 140 and the busbar 120, making it possible to further distribute the stress acting on the fixed portion 140. As a result, it is possible to reduce the possibility of the fixed portion 140 peeling off.

[0021] FIG. 5 is a diagram illustrating the positional relationship between the substrate 110 and the fixing portion 140. By increasing the contact area between the fixing portion 140 and the substrate 110, the stress acting on the fixing portion 140 is further dispersed. Therefore, it is preferable to set the difference between the length L3 of the substrate 110 in the X-axis direction (i.e., the width of the substrate 110) and the length L4 of the two fixing portions 140 in the X-axis direction to be equal to or less than the second distance. By doing so, the contact area between the fixing portion 140 and the substrate 110 is increased, and the stress acting on the fixing portion 140 can be further dispersed. As a result, it is possible to reduce the possibility of the fixing portion 140 peeling off.

[0022] <Through hole 111> 6, the substrate 110 may have a through-hole 111 into which at least a portion of the fixing portion 140 fits. This increases the contact area between the fixing portion 140 and the substrate 110, and further distributes the stress acting on the fixing portion 140. Furthermore, gas can be released through the through-hole 111, reducing the possibility of voids occurring in the fixing portion 140. Furthermore, it becomes possible to check the state of absorption of the material (solder) of the fixing portion 140 from the top surface side of the substrate 110, making it easier to determine whether the fixing state is good or bad.

[0023] 6 and 7, the entire through hole 111 may be blocked by the fixing portion 140, or as shown in Fig. 8, only a part of the through hole 111 may be blocked by the fixing portion 140. In this case, the above-mentioned fixing pattern may be arranged on the entire inner surface of the through hole 111, or the above-mentioned fixing pattern may be arranged on only a part of the inner surface of the through hole 111.

[0024] Furthermore, when the entire through hole 111 is blocked by the fixing portion 140, lands for the fixing portion 140 may be formed on the upper surface of the substrate 110, as shown in Figures 6 and 7. In this way, the fixing portion 140 has a rivet-like shape, and the substrate 110 is sandwiched between the fixing portions 140. As a result, the tensile strength of the fixing portion 140 is improved by the anchor effect, and it is possible to further reduce the possibility of the fixing portion 140 peeling off. In this case, it is preferable to arrange the above-mentioned fixing pattern around the through hole 111 on the upper surface of the substrate 110.

[0025] If the material of the fixing portion 140 is solder, by adjusting the amount of solder and the flow conditions (temperature, time), the solder can be sucked up through the through hole 111 to the top surface of the substrate 110, forming a land.

[0026] There may be one through hole 111 for each of the two fixing portions 140, or multiple through holes 111 as shown in Fig. 6. When there are multiple through holes 111 for each of the fixing portions 140, the multiple through holes 111 may be arranged, for example, at both a location corresponding to the first portion 141 of the fixing portion 140 and a location corresponding to the second portion 142 of the fixing portion 140, as shown in Fig. 6. In other words, the multiple through holes 111 may be arranged in a U-shape, similar to the fixing portion 140, as shown in Fig. 6. This increases the contact area between the fixing portion 140 and the substrate 110, and further distributes the stress acting on the fixing portion 140.

[0027] 9, when there are multiple through holes 111 for each fixing portion 140, the fixing portion 140 may be divided into multiple parts so that there is a one-to-one correspondence with the multiple through holes 111. In this way, it becomes possible to allow gas to escape also from the lower surface of the substrate 110, and it becomes possible to further reduce the possibility of voids occurring in the fixing portion 140.

[0028] 10 , in each of the two busbar portions 121, it is preferable that one of the multiple fixed portions 140 is connected to a reference voltage and the other fixed portion 140 is connected to a voltage source Vin via a resistor R. This makes it possible to measure the contact resistance between the fixed portion 140 and the busbar 110, and as a result, it becomes possible to detect peeling of the fixed portion 140 based on the measurement of this contact resistance. In each of the fixed portions 140 connected to the voltage source Vin via the resistor R, as the fixed portion 140 peels, that is, as the contact area between the fixed portion 140 and the busbar portion 121 becomes smaller, the contact resistance between the fixed portion 140 and the busbar 110 increases, and the voltage value Vout between the fixed portion 140 and the resistor R increases.

[0029] 10, fixed portion 140 connected to the reference voltage is present on both of two busbar portions 121, but as shown in Fig. 11, fixed portion 140 connected to the reference voltage may be present on only one of two busbar portions 121. In this way, it is also possible to measure the contact resistance between fixed portion 140 and busbar 110.

[0030] The present invention has been described above in terms of preferred embodiments thereof. While the present invention has been described herein with reference to specific examples, various modifications and variations can be made to these examples without departing from the spirit and scope of the present invention as set forth in the claims. [Explanation of symbols]

[0031] 100 Current Sensor 110 Substrate 111 Through hole 120 Shunt resistor integrated busbar 121 Busbar part 122 Shunt resistor part 130 Electrical Connections 140 Fixed part 141 First portion of fixed portion 140 142 second part of the fixed part 140

Claims

1. A substrate on which wiring is arranged; a shunt resistor-integrated bus bar having two bus bar portions and a shunt resistor portion connected between the two bus bar portions; an electrical connection portion for electrically connecting the wiring and the bus bar portion; a fixing portion for fixing the substrate to the shunt resistor-integrated bus bar, When the longitudinal direction of the shunt resistor-integrated bus bar is defined as an X-axis direction and the width direction of the shunt resistor-integrated bus bar is defined as a Y-axis direction, The fixing portion is provided in each of the two bus bar portions. a first portion extending in the Y-axis direction; a pair of second portions extending from both ends of the first portion in the Y-axis direction toward a shunt resistor portion; The electrical connection is disposed between the pair of second portions.

2. The current sensor according to claim 1 , wherein a difference between a length of the bus bar portion in the Y-axis direction and a length of the fixing portion in the Y-axis direction is equal to or less than a first distance.

3. The current sensor according to claim 1 , wherein a difference between the length of the substrate in the X-axis direction and the length of the entire fixed portion in the X-axis direction is equal to or less than a second distance.

4. The current sensor according to claim 1 , wherein the substrate further has a through-hole into which at least a portion of the fixing portion is inserted.

5. The current sensor according to claim 4 , wherein the fixing portion completely covers the through hole.

6. The current sensor according to claim 5 , wherein a land of the fixing portion is formed on a surface of the substrate opposite to a surface facing the shunt resistor-integrated bus bar.

7. The current sensor according to claim 4 , wherein the fixing portion closes a part of the through hole.

8. The through holes are plural, The current sensor according to claim 4 , wherein the plurality of through holes are arranged both at a location corresponding to the first portion of the fixed portion and at a location corresponding to the second portion of the fixed portion.

9. The through holes are plural, The current sensor according to claim 4 , wherein the fixing portion is divided into a plurality of portions so as to correspond one-to-one with the plurality of through holes.

10. The current sensor according to claim 9 , wherein at least one of the plurality of fixed portions is connected to a reference potential, and the other fixed portions are connected to a voltage source via resistors.

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