Current sensor

Abstract

To provide a current sensor capable of suppressing the rattling of a case against a bus bar.SOLUTION: A current sensor 1 includes a wiring board 3, a bus bar 2 superposed on one surface of the wiring board 3, and a case 6 housing the wiring board 3 and the bus bar 2. The case 6 is formed by assembling a first case 4 disposed on a side of the one surface of the wiring board 3, and a second case 5 disposed on a side opposite the one surface of the wiring board 3. An engaging part 44 of the first case 4 and an engagement receiving part 54 of the second case 5 are engaged by being moved closer in a thickness direction of the wiring board 3. Both ends of the bus bar 2 are each led out to the outside of the case 6 from between the first case 4 and the second case 5. The first case 4 has a pressing portion 46 which makes elastic contact with the bus bar 2 to press the bus bar 2 against the second case 5.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Current sensors incorporated into automotive power supply systems and the like include a structure in which a wiring board is soldered to a bus bar and sandwiched between an upper case and a lower case (see, for example, Patent Document 1). Both ends of the bus bar extend outside the case from between the upper and lower cases and are fastened to the bus bar of an electrical junction box or the like with bolts and nuts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-236981 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional current sensor described above, the upper and lower cases have backlash relative to the bus bar. This backlash is due to the dimensional tolerances required for assembling the upper and lower cases. However, this backlash causes noise when the vehicle is running, and so there is a need to reduce this backlash.

[0005] Therefore, an object of the present invention is to provide a current sensor that can suppress rattle of the case relative to the bus bar. [Means for solving the problem]

[0006] The present invention provides a current sensor comprising a wiring board, a bus bar superimposed on one surface of the wiring board, and a case accommodating the wiring board and the bus bar, wherein the case is assembled from a first case arranged on the one surface side of the wiring board and a second case arranged on the surface side of the wiring board opposite the one surface, the first case having a locking portion, the second case having a locking receiving portion that locks with the locking portion, the locking portion and the locking receiving portion being locked by being brought close to each other in the thickness direction of the wiring board, both ends of the bus bar extending out from between the first case and the second case, and the first case having a pressing portion that elastically contacts the bus bar and presses the bus bar against the second case. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a current sensor that can suppress rattle of the case relative to the bus bar. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a current sensor according to an embodiment of the present invention; [Figure 2] 2 is a see-through view of the inside of the case of the current sensor of FIG. 1. [Figure 3] FIG. 2 is a diagram showing the current sensor of FIG. 1 turned upside down. [Figure 4] 4 is a cross-sectional view of a portion of the current sensor of FIG. 3. FIG. [Figure 5] 5 is a diagram illustrating the action of the pressing portion of FIG. 4. FIG. [Figure 6] 5 is a diagram illustrating the action of the pressing portion of FIG. 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A "current sensor" according to one embodiment of the present invention will be described with reference to FIGS.

[0010] 1 to 6 is incorporated into an automobile power supply system, and is used, for example, to measure the current value of a high-voltage battery in an electric automobile. Current sensor 1 includes a wiring board 3, a bus bar 2 overlaid on one surface of wiring board 3, and a case 6 that houses wiring board 3 and bus bar 2. Current sensor 1 detects the current value by passing a current through bus bar 2 and detecting the potential difference across shunt resistor 20, which will be described later.

[0011] The bus bar 2 has a flat-plate-shaped first bus bar 21, a flat-plate-shaped second bus bar 22, and a shunt resistor (resistance element) 20 interposed between the first bus bar 21 and the second bus bar 22. The first bus bar 21 and the second bus bar 22 are arranged on the same plane. The shunt resistor 20 is electrically connected to the first bus bar 21 and the second bus bar 22 and mechanically connected to them. Therefore, the first bus bar 21, the second bus bar 22, and the shunt resistor 20 are integrated into a single plate.

[0012] Both ends of the bus bar 2, i.e., the end of the first bus bar 21 and the end of the second bus bar 22, are positioned outside the case 6. Circular through holes 21b, 22b are formed in the portions positioned outside the case 6. Both ends of the bus bar 2 are placed over bus bars such as an electrical junction box. Then, bolts are inserted into the through holes 21b, 22b, and nuts are fastened to the bolts, thereby fixing both ends of the bus bar 2 to the bus bars such as an electrical junction box. Furthermore, as shown in FIG. 2 , the first bus bar 21 and the second bus bar 22 are formed with notches 21a, 22a that match with the ribs 47 of the case 6.

[0013] The wiring board 3 is a printed circuit board, and is soldered to the first bus bar 21 and the second bus bar 22. A plurality of electronic components are mounted on the wiring board 3, and these components form a circuit that amplifies the potential difference across the shunt resistor 20.

[0014] The case 6 is formed by assembling a first case 4 arranged on the one surface side (busbar 2 side) of the wiring board 3 and a second case 5 arranged on the surface side opposite to the one surface of the wiring board 3. The first case 4 and the second case 5 are made of insulating synthetic resin.

[0015] The first case 4 has an opposing plate portion 41 facing the one surface of the wiring board 3, a side plate portion 42 standing upright from the outer edge of the opposing plate portion 41, the above-mentioned rib 47, a locking portion 44, and two pressing portions 46.

[0016] Two notches 43 are formed in the side plate portion 42 for leading both ends of the bus bar 2 out of the case 6. When the first case 4 and the second case 5 are assembled, the notches 43 form lead-out openings for the bus bar 2 between the first case 4 and the second case 5.

[0017] The ribs 47 are provided on both sides of the cutout 43. The ribs 47 match the cutouts 21a and 22a of the bus bar 2. This restricts the movement of the bus bar 2 in the longitudinal and width directions of the case 6.

[0018] The locking portions 44 are formed as protrusions that protrude outward from the outer surface of the side plate portion 42. The locking portions 44 are provided at a plurality of locations on the side plate portion 42.

[0019] The two pressing portions 46 are each connected to the opposing plate portion 41 and extend in a cantilevered manner, with their free ends in elastic contact with the bus bar 2. These pressing portions 46 are in elastic contact with the bus bar 2 to press the bus bar 2 against the second case 5. In this example, one pressing portion 46 is in elastic contact with the first bus bar 21, and the other pressing portion 46 is in elastic contact with the second bus bar 22. In this example, a rectangular through hole 45 is formed in the opposing plate portion 41, and the pressing portion 46 extends from the inner surface of the through hole 45 in a cantilevered manner.

[0020] The second case 5 has an opposing plate portion 51 facing the opposite surface of the wiring board 3, a side plate portion 52 standing upright from the outer edge of the opposing plate portion 51, and an engagement receiving portion 54 that engages with the above-mentioned engagement portion 44.

[0021] The locking receiving portion 54 is formed in a frame shape connected to the side plate portion 52. The locking receiving portion 54 is provided at multiple locations on the side plate portion 52. The locking portion 44 and the locking receiving portion 54 are locked by being brought close to each other in the thickness direction of the wiring board 3. The engagement of multiple pairs of the locking portion 44 and the locking receiving portion 54 maintains the assembled state of the first case 4 and the second case 5. The inner dimension of the frame of the locking receiving portion 54 is formed larger than the outer shape of the locking portion 44 to allow for dimensional tolerances.

[0022] As described above, in the current sensor 1 configured as described above, the two pressing portions 46 are in elastic contact with the bus bar 2, pressing the bus bar 2 against the second case 5. More specifically, as shown in FIG. 6 , the bus bar 2 is pressed against the tip of the side plate portion 52 of the second case 5 near the notch 43. This results in zero clearance between the locking portion 44 and the lock receiving portion 54 in the thickness direction of the wiring board 3. In this way, the current sensor 1 can suppress rattle with respect to the bus bar 2 while allowing for dimensional tolerances of the first case 4 and the second case 5.

[0023] Furthermore, although the wiring board 3 is fixed to the bus bar 2 with solder, the structure is such that the force applied to the bus bar 2 from the pressing portion 46 is transmitted directly to the second case 5, so no stress is applied to the solder connecting the bus bar 2 and the wiring board 3.

[0024] The above-described embodiment merely shows a typical form of the present invention, and the present invention is not limited to this embodiment. In other words, the present invention can be implemented with various modifications within the scope of the gist of the present invention. As long as such modifications still include the configuration of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0025] 1 Current Sensor 2 Busbar 3 Wiring board 4 Case 1 5. Case 2 6 cases 44 Locking part 54 Locking receiving part 46 Pressing part

Claims

1. a wiring board; a bus bar overlaid on one surface of the wiring board; and a case accommodating the wiring board and the bus bar; the case is formed by assembling a first case disposed on the one surface side of the wiring board and a second case disposed on the surface side opposite to the one surface of the wiring board, the first case has a locking portion, the second case has a locking receiving portion that is locked with the locking portion, and the locking portion and the locking receiving portion are locked by being brought close to each other in a thickness direction of the wiring board; Both ends of the bus bar are led out from between the first case and the second case to the outside of the case, The first case has a pressing portion that is in elastic contact with the bus bar and presses the bus bar against the second case. A current sensor characterized by:

2. the first case has an opposing plate portion that faces the one surface of the wiring board, the pressing portion is connected to the opposing plate portion and extends in a cantilevered plate shape, The free end of the pressing portion is in elastic contact with the bus bar.

2. The current sensor according to claim 1.

3. the bus bar includes a first bus bar having a flat plate shape, a second bus bar having a flat plate shape, and a resistive element interposed between the first bus bar and the second bus bar; The first case has two pressing portions, one of which is in elastic contact with the first bus bar and the other of which is in elastic contact with the second bus bar.

2. The current sensor according to claim 1.

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