JP2004325273A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a current sensor that is easily attached to an electric wire and removed from it in a short period of time, that has a slim shape, and that can be attached to each of electric wires because of the small size and light weight thereof. <P>SOLUTION: The current sensor includes a sensor element generating a signal by a current flowing into the wire, and a sensor case internally furnishing this sensor element and maintaining the position relationship between this sensor element and the wire. In the sensor case, a bag shaped internal fringe with an open part is contained, an electric wire inserting part is formed with the open end of the internal fringe with given proper spaces, an electric wire holding part is formed from the open end to the backside of the internal fringe is formed, the open-opposed parts of the electric wire inserting part are elastically energized in a direction mutually approaching until a proper space, and a ride-over projection having a slope is formed between the electric wire inserting part and electric wire holding part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a current sensor in which a current sensor element for detecting a current flowing through an electric wire is housed in a sensor case.
[0002]
[Prior art]
Conventionally, as such a current sensor, a split clamp type current transformer as shown in Patent Document 1 is known (FIG. 11). The sensor element of such a conventional current sensor has a magnetic core arranged annularly around the electric wire, a coil wound around the core, and a change in magnetic flux generated by the current flowing through the electric wire is captured by the core. The change in the magnetic flux of the core is converted into a voltage by a coil. The core was of a split type, in which the split point was manually opened, the electric wire to be measured was introduced into the core through the gap, and then the split point was closed and measured.
[0003]
[Patent Document 1] Japanese Patent Application Laid-Open No. 10-68749 (FIG. 9)
[0004]
[Problems to be solved by the invention]
However, in the above-mentioned conventional current sensor, firstly, since an annular closed core is used, the electric wire must be introduced from the outside of the annular core to the inside. Second, it is necessary to manually open and close the mouth of the core. Secondly, many current sensors use the magnetic flux generated by the current to set the measurable current and the range of the target wire. Therefore, there is a problem that a volume that does not saturate is required, and the inner diameter of the core cannot be reduced, so that the overall shape becomes large and heavy.
Therefore, although the conventional current sensor is suitable for use in accurately measuring the current flowing through a single wire over time, the current flowing in each of a plurality of densely packed wires can be simultaneously and individually measured. It was not suitable for applications such as measuring and repeating similar measurements at other locations. To this end, a small and lightweight current sensor that can be easily attached to and detached from electric wires, takes no time, and can be attached to each of slim and dense electric wires is desired.
Accordingly, the present invention provides a small and lightweight current sensor that can be easily attached to and detached from an electric wire, does not take much time, has a slim profile, and can be attached to each of densely packed electric wires. It is intended to provide. Such an electric current sensor is used for electrical wiring such as distribution boards, outlets, and lighting in houses, etc., when checking the electrical wiring using a wiring tester to check the wiring connection. Signal current is injected from the side, and the distribution board side detects the signal current for each wire connected to each branch circuit to check whether each outlet or lighting is connected to the predetermined branch circuit. It is assumed to be used for equipment. Of course, it is not limited to that.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to claim 1 of the present invention, a sensor element that generates a signal by a current flowing through an electric wire, and a sensor case that contains the sensor element and maintains a positional relationship between the sensor element and the electric wire are provided. The sensor case includes a bag-shaped inner peripheral edge with one opening, and the open end of the inner peripheral edge is a wire insertion part with an appropriate interval, and the inner peripheral edge from the open end to the back. A wire holding portion is formed on the wire insertion portion, and the opening facing portions of the wire insertion portion are elastically urged in a direction approaching each other until the appropriate space is reached, and have an inclined surface between the wire insertion portion and the wire holding portion. A current sensor is characterized by having overhang projections formed.
[0007]
According to a second aspect of the present invention, there is provided the current sensor according to the first aspect, wherein the entire sensor case has a rod-like and elongated shape, one end side is an open end, and a finger holding part is provided on the other end side. Provided.
[0008]
According to a third aspect of the present invention, the sensor case includes a main body member, a movable piece member, and a spring member. The movable piece member is supported by the main body member in a movable manner like a bird's beak, and includes a main body member and a movable piece member. 3. The current sensor according to claim 1, wherein a beak-shaped inner peripheral edge is the bag-shaped inner peripheral edge, and the open end is urged in a direction in which the open end approaches by a spring member. It is.
[0009]
According to a fourth aspect of the present invention, there is provided a current sensor according to the third aspect, wherein a pressing portion for an opening operation is formed on a side opposite to an opening end of the movable piece member with respect to a pivot portion. It is.
[0010]
According to a fifth aspect of the present invention, the sensor element is a coil or a Hall element that generates a signal by a magnetic flux generated by a current flowing through an electric wire. It provides the current sensor described.
[0011]
Embodiments of the present invention will be described below in detail with reference to the drawings.
FIGS. 1 and 2 are structural views showing an embodiment of the current sensor of the present invention. The current sensor includes one sensor case main body member, four movable piece members, ten urging means, and twelve sensor elements. The main body member 1 and the movable piece member 4 of the sensor case are formed of an insulating material such as a resin material and have an elongated rod shape as a whole.
The main body member 1 of the sensor case has a finger holding portion 2, a tip portion 3 formed in a substantially wedge shape, and a holding portion 11 for rotatably holding a movable sandwiching member member 4 described later. As shown in FIG. 2, a positioning portion 13 for fixing the arrangement position of the sensor element 12 and a current detection lead wire 14 electrically connected to the sensor element 12 are arranged and fixed inside the main body. For this purpose, a plurality of ribs 15 provided alternately are provided.
The movable piece member 4 is provided with a rotation center 7 at a substantially central portion, one of which has a sandwiching piece 5 and the other of which has a pressing portion 6. The movable piece member 4 is fitted and mounted on the holding portion 11 of the main body member 1 of the sensor case about the rotation center 7 as an axis, and is rotatably held. When the pressing portion is pressed, the opening operation is performed around the rotation center 7, and when the pressing is stopped, the closing operation is performed by the urging means described later.
The biasing means 10 is fitted between the main body member 1 of the sensor case and the pressing portion 6. In this embodiment, a helical spring is used, and the holding piece 5 is always formed in a substantially wedge shape. In the direction of the distal end portion 3 so as to be close to each other until an appropriate interval is reached.
FIG. 3 shows a state in which the electric wire 19 is sandwiched between the current sensors. The wire 19 is held by the wire abutting portion 8, the recessed wire holding portion 9 caused by the overhanging projection 18, and the sandwiching piece 5, and can always hold the wire at the same position.
The sensor element 12 uses a coil. FIG. 4 shows an enlarged view thereof. The sensor element 12 is provided with a coil part 121 and lead wires 122 extending from both ends of the coil part. A positioning part 13 is provided so that the coil part 121 and the lead wire 122 are fitted and fixed. Further, the coil portion is shielded from a magnetic field by using a magnetic material in order to improve the measurement accuracy by shielding the coil portion from an external magnetic field (not shown). As shown in the conventional example, in the split type or clamp type current transformer, the magnetic material is arranged in an annular shape so as to surround the circumference of the electric wire to be penetrated, so that the current transformer becomes heavier and sandwiched. Although there was a problem that the weight burdened the electric wire, in the present embodiment, a coil was used as the current detecting means, and the size was about the same as that of a normal lead electronic component. The weight is light, and combined with the resin molded body, the weight does not burden the wires even when sandwiched between the wires.
When a current signal flows through the electric wire, a magnetic flux is generated around the electric wire. The coil detects a magnetic flux linked to the coil and generates an induced electromotive force. The current flowing through the electric wire 19 can be detected by detecting the induced electromotive force. The fixed position of the sensor element 12 and the structure that holds the electric wire at the same position are combined, so that the positional relationship between the electric wire 19 and the sensor element 12 is always kept constant, and the detection of the magnetic flux linked to the coil is stabilized. It is possible to do. In this example, a coil is used as the sensor element, but a Hall element may be used.
FIG. 5 shows a view of the open end 20 of the current sensor. The movable piece 4 and the hidden line of the sensor main body member are shown by dotted lines. A substantially wedge-shaped distal end portion 3 and a sandwiching piece 5 of a movable piece member 4 disposed opposite to each other are rotatably supported by a bird's beak-like movable shaft around a rotation center 7. However, when the flat portion inside the sensor case main body 1 shown in FIG. 9A and the corner of the movable piece 4 shown in FIG. 9B come into contact with each other, the position is maintained and the opening interval is always provided. The opening interval is formed so as to become wider from the overhanging projection 18 toward the tip end. In addition, although the tip is configured to keep the interval wider than the diameter of the wire to be measured, since the wire itself is round, the interval may be smaller than the diameter and there is no problem if it is set to an appropriate size. .
In addition, the opening interval is the shortest at the portion of the overhanging projection 18, and the holding portion of the electric wire is wide so as to hold the electric wire. A bag-shaped inner peripheral edge is formed inside the projection 18, the wire holding portion 9, the wire butting portion 8, and the sandwiching piece 5 from the tip end portion 3.
Thus, when the current sensor is sandwiched between the electric wires 19, when the finger holding portion 2 is pressed against the electric wire from the open end portion 20 (the state shown in FIG. 6), the sandwiching piece 5 is rotated about the center of rotation. The opening operation is performed with the center as the center, and the electric wire enters the back of the sensor main body member 1 while sliding on the oblique side of the substantially wedge-shaped tip portion 3. When the wire gets over the overhanging projection 18 (the state shown in FIG. 7), the wire slides into the wire holding portion 9, and at the same time, the sandwiching piece 5 performs the closing operation by the urging means 10, and the recessed wire holding portion 9 and the wire abut. The electric wire is sandwiched and held by the portion 8 and the sandwiching piece 5 (the state of FIG. 8). As described above, if the current sensor is pressed against the electric wire, the electric wire can be sandwiched without pressing the pressing portion 6 of the movable piece 4.
The surface extending from the overhanging projection 18 to the recessed wire holding portion 9 is formed to be an inclined surface. For this reason, the wire can be effectively held, but the present invention is also effective when the current sensor is removed from the wire. When removing the current sensor from the electric wire, the operation of pulling out with the finger holding unit 2 is performed. In this case, since the slope between the overhang projection 18 and the recessed wire holding portion 9 is formed as an inclined surface, the electric wire moves over the projection 18 against the urging by the urging means 10. I will do it. The sandwiching piece 5 performs the opening operation, the wire climbs over the climbing projection 18 (the state of FIG. 7), the wire moves while sliding on the substantially wedge-shaped oblique side, and the sandwiching piece 5 performs the closing operation. The current sensor can be removed from the wire. As described above, if the current sensor is pulled out from the electric wire, it is possible to remove the current sensor from the electric wire without pressing the pressing portion 6 of the movable holding piece 4.
The movable piece 4 is disposed in a direction opposite to the finger holding portion 2 from a substantially central portion of the sensor main body member 1 and is smaller than the main body member. The pressing portion 6 is configured so as not to protrude greatly from the sensor main body member 1, and is formed so as to have an elongated rod shape as a whole outer periphery of the current sensor housing. When the pressing part is configured to be the same size as the finger holding part, and when multiple current sensors are used in a place where the wires are dense, the sensors overlap and work when pinching or removing the wires. Since the efficiency may not be excellent in some cases, the pressing portion is configured not to protrude significantly from the sensor main body 1. In this way, the current sensor housing is formed so as to have an elongated rod shape as a whole, so even if multiple current sensors are used in places where the wires are densely packed, it is efficient without reducing the work efficiency. It is possible to work.
In this embodiment, a helical spring is used as the urging means 10. However, a leaf spring may be used. Alternatively, as shown in FIG. The current sensor may be configured such that the member and the movable piece member are integrally resin-molded so as to have elasticity, and are elastically urged without using the urging means 10.
[0024]
【The invention's effect】
As described above, according to the present invention, a small and lightweight current sensor that can be easily attached to and detached from an electric wire, takes no time, and can be attached to each of slim and dense electric wires. It is possible to provide a current sensor with high working efficiency, which does not require opening / closing operation of clamps when attaching / detaching wires to / from electric wires and enables attaching / detaching only by inserting / pulling out wires. it can.
[Brief description of the drawings]
FIG. 1 is a perspective view of a current sensor according to an embodiment of the present invention.
FIG. 2 is an internal structural diagram of a current sensor.
FIG. 3 is a diagram showing a state where an electric wire is sandwiched.
FIG. 4 is an enlarged view of a current detection unit.
FIG. 5 is a diagram showing a state in which an electric wire is not sandwiched.
FIG. 6 is an explanatory diagram when an electric wire is sandwiched.
FIG. 7 is an explanatory view when an electric wire is sandwiched.
FIG. 8 is an explanatory view when an electric wire is sandwiched.
FIG. 9 is a diagram showing an open end of the current sensor.
FIG. 10 shows another example of a current sensor. FIG. 11 is a diagram showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Body member of sensor case 2 Finger holding part 3 Tip part 4 Movable piece 5 Nipping piece 6 Pressing part 7 Rotation center 8 Electric wire butting part 9 Electric wire holding part 10 Energizing means 11 Holding part 12 Sensor element 13 Positioning part 14 Current Detection lead wire 15 Rib 16 Opening interval a
17 Opening interval b
18 Overhang projection 19 Electric wire 20 Open end 21 Inner peripheral edge 121 Coil part 122 Lead wire

Claims (5)

A sensor element for generating a signal by a current flowing through an electric wire, and a sensor case for housing the sensor element and maintaining a positional relationship between the sensor element and the electric wire, wherein the sensor case includes a bag-shaped inner peripheral portion having an open portion. The opening end of the inner peripheral edge is provided with an appropriate interval to form a wire insertion portion, and a wire holding portion is formed on the inner peripheral edge on the back side from the opening end. A current sensor characterized by being elastically biased in a direction approaching each other until an appropriate distance is reached, and having a climbing protrusion having an inclined surface formed between the wire insertion portion and the wire holding portion. 2. The current sensor according to claim 1, wherein said sensor case has a rod-like and elongated shape as a whole, an open end at one end side, and a finger holding portion provided at the other end side. The sensor case includes a main body member, a movable piece member, and a spring member. The movable piece member is rotatably supported in a bird's beak shape with respect to the main body member, and has a beak-shaped inner peripheral edge composed of the main body member and the movable piece member. The current sensor according to claim 1 or 2, wherein the inner peripheral edge of the bag is urged by a spring member in a direction in which the open end approaches. 4. The current sensor according to claim 3, wherein a pressing portion for opening operation is formed on a side opposite to an opening end of the movable piece member with respect to a shaft support portion. 5. The current sensor according to claim 1, wherein the sensor element is a coil or a Hall element that generates a signal by a magnetic flux generated by a current flowing through an electric wire.

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