JP2009092539A - Clamp meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clamp meter excellent in operability and portability capable of easily and safely reading the current display value even when measuring the current flowing in a conductor to be measured placed in a wire converging place. <P>SOLUTION: The clamp meter includes a CT-side case section with a clamp type CT section clamped on the conductor to be measured at one end of the length direction, and a display-side case section that is connected to the other end side and has a display window for displaying the current value flowing in the conductor to be measured. The relative position between the display-side case section and the CT-side case section is variable. Both the case sections may be interconnected through a movable connecting means or may be interconnected removably. In the former case, a wire for connecting between circuit blocks built in both the case sections is arranged inside the movable connecting means. In the latter case, both the case sections are or can be interconnected through the wire. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a clamp meter that can easily read a display value of a current flowing through a measured electric wire even in a place where a plurality of electric wires such as a distribution board is congested.

  The clamp meter is a handy type ammeter that can easily measure a current flowing through an electric wire to be measured such as an electric wire and has excellent portability. FIG. 8 is a perspective view schematically showing the appearance of an example of a conventional digital clamp meter. The clamp meter shown in this figure comprises an elongated main body 6 having a clamp-type CT section 11 at one end, and the main body 6 is provided with a display window 21 near the end on the near side. The clamp-type CT unit 11 is composed of two holders 11a and 11b made of a resin molded product containing a substantially semi-circular magnetic core, and the base ends (not shown) of these holders 11a and 11b are usually The main body 6 is pivotally supported so as to be rotatable in a state of being biased in the approaching direction by a tension coil spring interposed therebetween. In FIG. 8, the measurement range and measurement magnification changeover switches on the front surface of the clamp meter body 6 are omitted.

  FIG. 9 is a functional block diagram inside a general digital display clamp meter. As shown in this figure, the current signal detected by the clamp-type CT unit 11 that clamps the conductor to be measured is converted into a voltage signal by the shunt resistor unit 52. The converted voltage signal is amplified to a predetermined signal level by the signal amplifying unit 53, unnecessary noise is removed by the filter unit 54, and then converted into a DC voltage signal by the AC (effective value) and DC conversion unit 55. Further, it is converted into a digital signal by the A / D converter unit 56. The digital signal is decoded by the calculation unit 57 and is sent to the display unit 58 after the unit display and the decimal point position corresponding to the switching of the measurement range and the measurement magnification are set. Is digitally displayed.

  When using such a clamp meter to measure the current flowing through the wiring behind the place where the wiring is congested, such as inside the switchboard, the clamp meter is inserted by separating the front wiring, and the clamp meter is inserted into the wiring to be measured. Even if it can be set, the surrounding wiring may be in the way and the orientation of the clamp meter may not be changed so that the display window faces the measurer. In particular, when the surrounding wiring is a thick and hard wire, it is very difficult to point the display window of the clamp meter toward the measurer. In this case, in order to read the current display on the display window, the measurer needs to bring his face close to the front wiring, the terminal block to which these are connected, and there is a problem in terms of safety. In addition, when the switchboard is installed in a narrow space, the measurer may have to be in an unsafe posture, and checking the current display of the clamp meter in such a state is further Not easy.

  Under such circumstances, in recent years, a clamp meter that can separate the clamp-type CT portion of the clamp meter and its opening / closing mechanism from the instrument body has been proposed (see, for example, Patent Document 1). However, in the clamp meter of Patent Literature 1, the clamp-type CT part is separated together with the clamp opening / closing mechanism and the display-side main body part is installed at the measurer's hand so that the wiring behind the switchboard as described above can be provided. Although it is easy to read the display of the flowing current, it is difficult to open and close the CT section because the portion that can be gripped by the measurer is small in the separated CT section, although a certain amount of force is required to open and close the CT section. There is a problem in terms of operability.

Also, it is a clamp-type CT configured as an ammeter by connecting to a separate display, and in order to make the CT easy to open and close, the gripping case provided at one end is lengthened and large-sized (For example, refer to Patent Document 2). According to this ammeter, the risk of unsafeness as described above is reduced and operability is good, but the ammeter as a whole becomes large and the CT unit and the display must be carried separately. There is a difficulty in portability.
JP 2004-361248 A JP-A 64-54269

  Therefore, in view of the above circumstances, the present invention can easily and safely read the current display value even when measuring the current flowing through the conductor under measurement in a place where such wiring is congested, and is easy to operate and portable. An object of the present invention is to provide an excellent clamp meter.

  In order to achieve the above object, a clamp meter according to the present invention is connected to a CT-side housing portion having a clamp-type CT portion clamped to a conductor to be measured at one end in the length direction and the other end side, and The display-side housing portion is provided with a display window for displaying a current value flowing through the conductor, and the relative position between the display-side housing portion and the CT-side housing portion is variable.

  In order to make the relative positions of these two housing parts variable, the two casing portions may be connected via movable connecting means, or may be connected detachably. In the former case, the movable connecting means includes an output line of the clamp-type CT unit connected to a circuit block built in the display-side housing part, or a circuit block incorporated in both housing parts. An electric wire that connects the two can be disposed. Here, in this specification, the term “circuit block” is used in principle when each block element shown in the figure (provided that the clamp-type CT is provided) when a block diagram is prepared for the internal wiring of the clamp meter of the present invention. 2) and two or more electrically connected block element groups, but only the latter block element group needs to be indicated. And “circuit block including a plurality of block elements”.

  Further, an intermediate housing portion is further interposed between the CT side housing portion and the display side housing portion, and between the intermediate housing portion and the CT side housing portion and the display side housing portion. The movable connecting means can also be provided respectively.

  Further, in the latter detachably connected configuration, the circuit blocks including a plurality of block elements incorporated in each of the two casing parts can be connected or connected via electric wires, and the circuit blocks can be connected to each other. Thus, it can be configured such that signal transmission and power supply are performed.

  According to the present invention, the housing of the clamp meter is composed of at least two parts, that is, a CT-side housing part and a display-side housing part, and these two housing parts are connected or removed via the movable connecting means shaft. Since these relative positions can be made variable by freely connecting them, even when measuring the current flowing through the conductor under measurement where the wiring is congested, the measurer must clamp the conductor under measurement after clamping it. The direction of the display-side casing portion can be changed or separated from the CT-side casing portion to direct the display window to itself, and the current display on the display window can be easily read. As a result, the measurer does not need to bring his face close to the terminal block in front of the display window in order to read the current display on the display window, and the safety is also improved.

  Further, since the movable connecting means for connecting the two housing parts can be designed compactly, it is not necessary to make these two housing parts almost large, and the two housing parts can be detachably attached. Even in the case of connection, since a circuit block including a plurality of block elements is also arranged especially in the CT side housing portion, it is possible to achieve downsizing as much as a conventional clamp meter and to improve portability.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiment is a digital clamp meter having the same basic configuration as the conventional clamp meter shown in the background art (FIGS. 8 and 9), but the present invention is not limited to these embodiments. It is not something that can be done. In the following drawings, the same reference numerals are used for parts that are the same as or common to the parts in the conventional clamp meter described in the background art, and redundant description is omitted.

[Embodiment 1]
FIG. 1 is a perspective view schematically showing an example of an embodiment of a clamp-type ammeter according to the present invention in which the relative positions of a CT-side housing part and a display-side housing part are variable using a movable connecting means. FIG. 2 is a cross-sectional view showing the internal structure of the CT-side housing portion (a part near the display-side housing portion) and the display-side housing portion of the embodiment shown in FIG. In these drawings, the clamp meter 1 of the present embodiment is connected to a CT-side housing portion 10 having a clamp-type CT section 11 at one end and the other end in the length direction, and is connected to the clamp-side housing portion 10. A display-side housing portion 20 having a display window 21 on the front surface near the end opposite to the facing end is provided. The material of these two housing parts is not particularly limited, and can be formed of a known material such as plastic.

  The CT-side housing portion 10 and the display-side housing portion 20 have contact surfaces 10a and 20a that can contact each other in a substantially right shape in a direction perpendicular to the length direction. Through holes 10b and 20b penetrating inward and outward are formed at substantially the centers of the contact surfaces 10a and 20a, respectively. These through-holes 10b and 20b are arranged so as to face each other when the CT-side housing portion 10 and the display-side housing portion are brought into contact with the contact surfaces 10a and 10b.

  The shaft 5 as the movable connecting means has a short cylindrical shape with a circular cross section, and is attached in a state of being inserted into each of the through holes 10b and 20b. At both ends of the shaft 5 in the opening direction, outer casings 5a and 5b extending on the outer edges in the radial direction are provided on the same edge, and these outer casings 5a and 5b are provided on both housing parts. The two housing parts 10 and 20 are connected to each other so as to be rotatable without being separated from each other by being engaged and disposed in the respective parts 10 and 20. If the shaft 5 has a strength characteristic that does not easily break when an external force such as a tensile force or a shearing force is applied to the CT-side housing portion 10 or the display-side housing portion 20, the material of the shaft 5 is not limited. Is not particularly limited, but is preferably formed of an insulating material.

  In the clamp meter 1 of the present embodiment, as shown in FIG. 2, circuit blocks 15 and 23 are built in the CT-side housing portion 10 and the display-side housing portion 20, respectively. 23 is electrically connected by an electric wire 16. The circuit block 23 in the display-side housing portion 20 includes at least a display unit (including the display window 21) for digitally displaying a current value, and one or two other connected to the display unit. The above (see FIG. 9) can be included as appropriate. In addition, the circuit block 15 of the CT-side casing portion 10 can include a remaining portion that is not included in the circuit block 23 for processing of an output signal from the clamp-type CT unit 11 among the units illustrated in FIG. 9. From the viewpoint of signal transmission, this circuit block 15 preferably includes at least a shunt resistor section 52, a signal amplification section 53, and a filter section 54.

  One end of the electric wire 16 is connected to the circuit block 15 in the CT-side housing portion 10, the other end is inserted through the opening of the shaft 5, and is connected to the circuit block 23 in the display-side housing portion 20. Accordingly, signal transmission is performed from the circuit block 15 in the CT-side casing portion 10 to the circuit block 23 in the display-side casing portion 20. As such an electric wire 16, in addition to a normal covered electric wire, a flat cable or the like can be used when a digital signal is transmitted by this. Moreover, although only one electric wire 16 is disposed in FIG. 2, the electric wire 16 is not limited to this, and may be composed of a plurality of wires if necessary. Furthermore, when the electric power is built in either of the two casing parts 10 and 20 in the electric wire 16, the casing part (10 or 20) provided with the power source is used for the other casing part ( 20 or 10) may be included. In this embodiment, the circuit block 15 is built in the CT-side casing portion 10 as described above, but the circuit block 15 is not built in the CT-side casing portion 10 and is clamped CT section. Eleven output lines may be directly introduced into the display-side casing portion 20 as the electric wires 16.

  By inserting the electric wire 16 through the shaft 5 in this way, even when the display-side housing portion 20 is rotated with respect to the CT-side housing portion 10, a clamp-type CT in which a conductor to be measured (not shown) is clamped. The output signal from the section 11 is processed by the circuit blocks of these two casing portions 10 and 20, and the current value is displayed on the display window 21.

  When the current flowing through the conductor to be measured (not shown) in the switchboard or the like is measured using the clamp meter 1 of the present embodiment, the clamp-type CT unit 11 is attached to the conductor to be measured without rotating the display-side housing portion 20. After clamping, by rotating the display-side housing portion 20, the relative position of the display-side housing portion 20 with respect to the CT-side housing portion 10 can be changed. As a result, the measurer can easily read the current display. The position of the display window 21 can be changed.

[Embodiment 2]
FIG. 3 is a perspective view schematically showing an example of an embodiment of the clamp meter of the present invention, and FIG. 4 is a CT side housing portion (a part near the display side housing portion) of the embodiment shown in FIG. It is sectional drawing which shows the internal structure of a display side housing | casing part. In the clamp meter 2 of this embodiment, it is connected via the hinge part 6 (movable connection means) provided in the edge part of CT side housing | casing part 10 and the display side housing | casing part 20. FIG. The configuration other than the hinge portion of this embodiment and the material of each portion are not essentially different from those of the first embodiment.

  As shown in FIGS. 3 and 4, the hinge portion 6 as the movable connecting means has the following configuration. Two engaging members provided with semi-cylindrical curved surfaces 13a and 14a at the end of the CT-side housing portion 10 facing the display-side housing portion 20 from both side edges toward the display-side housing portion 20 13 and 14 are projected. The engaging members 13 and 14 are substantially the same shape as each other, and the central axes of these half cylinders are arranged to coincide with each other. Further, the end faces facing each other toward the inside of the engaging members 13 and 14 are closed, and through holes 13b and 14b through which the cylindrical shafts 7 can be inserted are formed at substantially the center of these closed faces. Has been. The engaging members 13 and 14 can be formed of the same or different material as the CT side housing part 10, but preferably the same material and formed integrally with the CT side housing part 10 are used. Is good.

  On the other hand, an end portion of the display-side housing portion 20 facing the CT-side housing portion 10 projects from the center toward the CT-side housing portion 10 and is formed between the two engaging members 13 and 14. An engaging member 24 having a semi-cylindrical curved surface 24a that fits into the gap is provided. Both side surfaces of the engaging member 24 that come into contact with the end surfaces facing the inside of the engaging members 13 and 14 are closed, and a substantially central portion thereof is penetrated to a position corresponding to the position of the through holes 13b and 14b. Holes 24b and 24b are formed. The engaging member 24 can also be formed of the same or different material as the display-side casing portion 20, but preferably the same-quality material that is formed integrally with the display-side casing portion 20 is used. Good.

  The engaging members 24 are disposed between the engaging members 13 and 14 so that the through holes 13b and 14b of the engaging members 13 and 14 and the through holes 24b and 24b of the engaging member 24 are arranged on the same straight line. And the cylindrical shaft 7 is attached so as to penetrate each of the through holes 13b, 14b, 24b, 24b.

  At both ends in the opening direction of the shaft 7, outer flanges 7 a and 7 b are provided on the edge thereof so as to extend radially outward, and the outer flanges 7 a and 7 b are respectively engaged with the engaging member 13. , 14, the engaging member 24 is rotatably fixed to the engaging members 13, 14. As shown in FIG. 4, an electric wire insertion hole 7 c is formed in the intermediate peripheral surface of the shaft 7, and the electric wire 16 having one end connected to the circuit block 15 in the CT-side housing portion 10 is provided. The electric wire insertion hole 7 c is passed through from one opening end of the shaft 7, and the other end is connected to the circuit block 23 in the display-side housing portion 20. If the shaft 7 has a strength characteristic that does not easily break when an external force such as a tensile force or a shearing force is applied to the CT-side housing portion 10 or the display-side housing portion 20, the material of the shaft 7 is not limited. Is not particularly limited, but is preferably formed of an insulating material.

  The display side housing portion 20 is sandwiched between the engagement members 24 and the end surface 10c of the display side housing portion 20 facing the outer peripheral surface 24a of the engaging member 24 and the engaging member 24. End surfaces 20a, 20a provided on both side edges of the CT side housing portion 10 and facing the outer peripheral surfaces 13a, 14a of the engaging members 13, 14 of the CT side housing portion 10, respectively, are the outer peripheral surfaces of these engaging members 13, 14, 24. It is formed as a closed surface having an appropriate shape to the extent that it does not contact 13a, 14a, 24a. Preferably, these end surfaces 10c, 20a, 20a have a radius slightly larger than the radius of the outer peripheral surfaces 13a, 14a, 24a of the opposing engaging members 13, 14, 24, and are spaced from these outer peripheral surfaces. It is preferable to exhibit a semi-cylindrical shape that keeps the above constant.

  By providing such a hinge portion 6, the clamp meter 2 of the present embodiment clamps the clamp-type CT portion 11 on the conductor to be measured, and the current is displayed in the display window 21 disposed on the front surface of the display-side housing portion 20. The display-side housing portion 20 can be bent with respect to the CT-side housing portion 10 while displaying values. In using the clamp meter 2 of the present embodiment, as in the clamp meter of the first embodiment, the conductor to be measured is clamped without bending the display-side housing portion 20 with respect to the CT-side housing portion 10. The CT section 11 can be clamped, and then the display-side housing portion 20 can be bent to direct the display window 21 toward the measurer. Thereby, the measurer can easily read the current value flowing through the conductor under measurement from the display window 21 even in a place where the wiring is congested, such as in the switchboard.

[Embodiment 3]
FIG. 5 is a perspective view schematically showing an example of an embodiment of the clamp-type ammeter of the present invention. The CT-side housing portion (a part near the display-side housing portion) of the embodiment shown in FIG. It is sectional drawing which shows an internal structure with a display side housing | casing part. In the clamp meter 3 of the present embodiment, an intermediate housing portion 30 is interposed between the CT-side housing portion 10 and the display-side housing portion 20, and the intermediate housing portion 30, the CT-side housing portion 10 and the display are displayed. The side housing portion 20 is connected by the movable connecting means shown in the first and second embodiments. That is, the CT-side housing portion 10 and the intermediate housing portion 30 are connected via the shaft 5 as movable connecting means provided along the length direction of the clamp meter, and the intermediate housing portion 30 and the display are displayed. It is connected with the side housing | casing part 20 via the hinge part 6 as an operation | movement connection means. Since the structure of these movable connecting means and the internal structure of these three members have already been described, they are omitted here.

  In the clamp meter 3 according to the present embodiment, the display-side housing portion 20 includes two movable connecting means, that is, the shaft 5 and the hinge portion 6. Therefore, by combining these movable connecting means, the CT-side housing portion can be further increased. The relative position of the display-side casing portion 20 with respect to 10 can be changed in a complicated manner. Thereby, even if it is difficult to read the current display on the display window 21 by the clamp meter of the first embodiment or the second embodiment, the measurer can use the clamp meter 3 of the present embodiment. The display window 21 can be directed to itself.

[Embodiment 4]
FIG. 7 is a diagram showing still another example of the embodiment of the clamp meter of the present invention. As shown in this figure, the clamp meter of this embodiment has a configuration in which the CT-side housing portion and the display-side housing portion are detachably connected without using the movable connecting means shown in the previous embodiment. As a result, the relative positions of the two casing portions are variable.

  As shown in FIG. 7, the connecting structure of the two housing parts 10 and 20 is formed with concavo-convex portions nested in the opposing ends of the CT housing part 10 and the display housing part 20, respectively. The structure which inserts the display side housing | casing part 20 in the CT side housing | casing part 10 can be mentioned. In this case, small dents 18 and 19 are respectively provided at predetermined positions on the inner peripheral surface of the CT-side housing portion 10 facing the concave portion, and correspond to the dent on the outer peripheral surface of the convex portion of the display-side housing portion 20. The protrusions 26 and 27 can be provided at the positions, respectively. As a result, when the display-side housing portion 20 is mounted on the CT-side housing portion 10, the projections 26 and 27 are fitted into the two dents 18 and 19, and both the housing portions 10 and 20 are easily detached. You can avoid it. In addition, the connection structure of the said housing parts 10 and 20 is not restricted to this, It is good also as another well-known structure.

  As shown in FIG. 7B, the circuit block 15 built in the CT-side housing portion 10 has three block elements: a shunt resistor section 52, a signal amplifying section 53, a filter section 54, and an AC / DC conversion section 55. Is included. Further, the circuit block 23 built in the display-side casing portion 20 includes three block elements, that is, an A / D converter unit 56, a calculation unit 57, and a display unit 58. Note that the circuit blocks 15 and 23 are not limited to such a combination of block elements, and may include other combinations as long as each circuit block includes a plurality of block elements electrically connected. is there.

  In addition, the electric wires 40 that electrically connect the circuit blocks 15 and 23 have connection connectors 41 and 42 attached to both ends thereof, respectively, and these connectors contact the housing parts 10 and 20. It is adapted to be fitted to mating connection connectors 41 and 42 provided on the respective surfaces. The electric wire 40 may be accommodated in the connecting structure in a state where the electric wire 40 is connected to the circuit blocks 15 and 23 included in the housing portions 10 and 20, respectively.

  As described above, the CT-side housing portion 10 and the display-side housing portion 20 are detachably connected, and the two housing portions 10 and 20 are separated at the time of measurement, so that their relative positions can be arbitrarily changed. Further, by incorporating the circuit blocks 15 and 23 each having a plurality of block elements in each of the housing portions 10 and 20, the compactness can be achieved and the portability can be improved similarly to the conventional clamp meter. In using the clamp meter 4 of the present embodiment, the conductor to be measured is clamped by the clamp-type CT unit 11 with the display-side housing part 20 attached to the CT-side housing part 10, and then the display-side housing. What is necessary is just to isolate | separate the body part 20 and to install this in the position where a measurer can read the electric current display on the display window 21 easily.

  As described above, in the clamp meter of the present invention, the housing is composed of at least the CT side housing portion and the display side housing portion, the relative positions of both housing portions are variable, and the current flowing through the conductor to be measured using this is used. When measuring, the measurer can change the orientation of the display-side housing, so even when measuring the current flowing through the conductor under measurement where the wiring is congested, the display window can be pointed at itself. The current value displayed there can be read easily and safely. Further, since the movable connecting means for connecting the two housing parts can be designed compactly, it is not necessary to make these two housing parts almost large, and the two housing parts can be detachably attached. Even in the case of connection, since a circuit block including a plurality of block elements is also arranged especially in the CT side housing portion, it is possible to achieve downsizing as much as a conventional clamp meter and to improve portability.

It is a perspective view showing typically an example of an embodiment of a clamp meter of the present invention. It is sectional drawing which shows the structure of the movable connection means of embodiment shown in FIG. It is a perspective view which shows typically another example of embodiment of the clamp meter of this invention. It is sectional drawing which shows the structure of the movable connection means of embodiment shown in FIG. It is a perspective view which shows typically another example of embodiment of the clamp meter of this invention. It is sectional drawing which shows the structure of the movable connection means of embodiment shown in FIG. It is a figure which shows another example of embodiment of the clamp meter of this invention. It is a perspective view which shows typically the external appearance about an example of the conventional digital clamp meter. It is a figure which shows the block diagram inside the clamp meter shown in FIG.

Explanation of symbols

1-4 Clamp meter 5 of the present invention Cylindrical shaft (movable connecting means)
5a, 5b Outer cage 6 Hinge (movable connecting means)
7 Cylindrical shafts 7a and 7b in the hinge portion 7c Outer rod 7c Electric wire insertion hole 10 CT side housing portion 10a Abutting surface 11 Clamp type CT portion 15 Circuit block 16 Electric wires 18 and 19 Recess 26 and 27 Protrusion 20 Display side housing Part 20a Abutting surface 21 Display window 23 Circuit block 40 Electric wires 41, 42 Connector 51 Magnetic core part (in the clamp-type CT part)
52 Shunt Resistor 53 Signal Amplifier 54 Filter 55 AC / DC Converter 56 A / D Converter 57 Computing Unit 58 Display

Claims (6)

  A display-side housing comprising a CT-side housing portion having a clamp-type CT section clamped to the conductor to be measured at one end in the length direction, and a display window connected to the other end to display the current value flowing through the conductor to be measured. A clamp meter comprising: a body portion, wherein a relative position between the display-side housing portion and the CT-side housing portion is variable.   The CT-side casing part and the display-side casing part are connected via movable connecting means that can change their relative positions, and the CT-side casing part is contained in the movable connecting means. The clamp meter according to claim 1, wherein an output line of the built-in clamp-type CT unit or an electric wire connecting between the circuit blocks housed in the housing parts is disposed.   The movable connecting means is constituted by cylindrical support shafts that pass through substantially the centers of the opposing end faces of the respective housing parts and connect these housing parts to each other, and the respective housing parts are mutually connected. The clamp meter according to claim 2, wherein the clamp meter is configured to be rotatable about the axis of the support shaft with respect to the counterpart.   The movable connecting means includes a hinge portion that connects opposite end portions of the casing portions, and the casing portion allows one of the casing portions to be bent with respect to the other. The clamp meter according to claim 2.   Between the CT-side casing part and the display-side casing part, there are interposed intermediate casing parts arranged respectively. The intermediate casing part, the CT-side casing part, The clamp meter according to any one of claims 2 to 4, wherein the movable connecting means is provided between each of the display side housing portions.   The CT-side housing part and the display-side housing part are detachably coupled, and the circuit blocks including a plurality of block elements incorporated in each of the housing parts are connected or connected by the electric wires. The clamp meter according to claim 1, which is made possible.

Images