JP2020173100A - Watt-hour meter - Google Patents

Abstract

To provide a watt-hour meter in which an operator can perform sufficient tightening work for each terminal screw.SOLUTION: A watt-hour meter comprises a terminal part configured to connect a solderless terminal to a terminal metal fitting. The terminal part comprises: an insulated space which is defined by a partition part of an insulation housing; a terminal metal fitting which is secured in the insulated space; a nut which is secured to the terminal metal fitting in the insulated space; and a terminal screw which is configured to be tightened via the solderless terminal and the terminal metal fitting to the nut. The partition part comprises at least one crushable protrusion part which is provided on a side opposite to a nut side with respect to the terminal metal fitting and protrudes into the insulated space.SELECTED DRAWING: Figure 3A

Description

The present invention relates to a watt hour meter.

Conventionally, an electronic watt-hour meter is known as a watt-hour meter for measuring the amount of electric power used by a consumer. The electronic watt-hour meter consists of a terminal unit where terminal fittings to which distribution lines are connected are arranged, a power calculation unit that calculates power, a display unit that displays the amount of power, and a central control unit that controls each unit. It is configured. The board and display on which the electronic components that make up the power calculation unit and central control unit are mounted are fixed to the housing by screwing, etc., and electricity is used between the terminal and the board and between the board and the display by cables or the like. Is connected.

In the terminal portion, the connection between each terminal fitting and the distribution line is usually performed by screw tightening. Specifically, using the attached terminal screw, the crimp terminal to which the distribution line is crimped is tightened and fixed to the terminal fitting.

Since it is necessary to tighten a plurality of terminal screws for one watt hour meter, the operator needs to efficiently tighten each terminal screw. Further, for example, in a building, a huge number of watt-hour meters may have to be replaced and installed all at once, and in such a case, efficient work is particularly required. On the other hand, the terminal screws need to be tightened carefully. It is recommended that the terminal screws be tightened with a torque within a predetermined range according to the specifications of the watt hour meter. If the tightening torque is smaller than the specified torque, the terminal screws may loosen and abnormal heat generation of the terminal portion may occur due to an increase in contact resistance. On the other hand, if the tightening torque is larger than the specified torque, the terminal fittings and / or the terminal screws may be damaged.

Therefore, conventionally, tightening of terminal screws is generally performed step by step using a general electric screwdriver and a torque driver or a torque wrench. Specifically, the operator first tightens the terminal screw using a general electric screwdriver. After that, the operator confirms the tightened state of each terminal screw by touching the cable of the distribution line by hand or the like. Then, only the terminal screws that are thought to be loose are further tightened with a torque driver or torque wrench until the specified torque value is reached (in other words, retightening is performed).

As described above, in the conventional tightening work, the confirmation of the tightening state mainly relies on the sense of the operator. However, the worker is not always an expert, and in that case, the worker may not be able to notice a slight looseness and may complete the installation of the watt-hour meter with insufficient tightening. There is. If the watt-hour meter is used with the terminal screws insufficiently tightened, the temperature of the terminal portion may rise due to an increase in contact resistance, and the resin housing may melt or ignite.

An embodiment of the present invention is an object of the present invention to provide a watt-hour meter capable of a worker to sufficiently tighten each terminal screw.

According to one embodiment of the present invention, there is provided a watt hour meter including a terminal portion configured to connect a crimp terminal to a terminal fitting. The terminal portion is via an insulating space defined by a partition wall of an insulating housing, a terminal fitting fixed in the insulating space, a nut fixed to the terminal fitting in the insulating space, a crimp terminal, and a terminal fitting. Includes terminal screws, which are configured to be fastened to nuts. The partition wall is provided on the side opposite to the nut with respect to the terminal fitting and includes at least one crushable protrusion protruding into the insulating space.

Further, according to one embodiment of the present invention, the power meter includes a terminal portion configured to connect a crimp terminal to a terminal fitting, and the terminal portion is defined by a partition wall portion of an insulating housing. An insulating space, a terminal fitting fixed in the insulating space, a nut fixed to the terminal fitting in the insulating space, and a terminal screw configured to be fastened to the nut via a crimp terminal and the terminal fitting. A power meter is provided that includes a crushable surface that is provided on the same side as the nut with respect to the terminal fitting and is located at a position facing the tip of the shaft of the terminal screw.

It is a front view which shows the watt-hour meter according to the 1st Embodiment of this invention. It is a figure which shows an example of a crimp terminal. It is a figure which shows the structure of the terminal part before the terminal screw is tightened. It is a figure explaining the tightening process of a terminal screw, and is the figure which shows the temporary tightening position of a terminal screw. It is a figure explaining the tightening process of a terminal screw, and is the figure which shows the final tightening position of a terminal screw. It is a figure which shows the structure of the terminal part of the watt hour meter according to the 2nd Embodiment, and is the figure which shows the structure of the terminal part before the terminal screw is tightened. It is a figure explaining the tightening process of a terminal screw, and is the figure which shows the temporary tightening position of a terminal screw. It is a figure explaining the tightening process of a terminal screw, and is the figure which shows the final tightening position of a terminal screw.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The following description is merely an example, and does not mean that the technical scope of the present invention is limited to the following embodiments. Further, in the drawings, the same or corresponding components are designated by the same reference numerals, and duplicate description will be omitted. In the following description, terms indicating directions such as "up" and "down" are used for convenience in order to facilitate understanding of the present invention, and are not intended to limit the present invention.

[First Embodiment]
FIG. 1 is a front view showing an electronic watt-hour meter 1000 as an example of the watt-hour meter according to the first embodiment. The electronic watt-hour meter 1000 is attached to the wall surface of a building or a house of a general household in the direction shown in the drawing. The electronic watt-hour meter 1000 of the first embodiment includes a terminal portion 100 configured to connect a distribution line (not shown) to the terminal fitting 108 by tightening the attached terminal screw 110. Reference numeral 112 denotes a liquid crystal display unit controlled by a central processing unit built in the electronic watt-hour meter 1000. However, the watt-hour meter according to the first embodiment is not limited to the electronic watt-hour meter. Further, in the illustrated example, the electronic watt-hour meter 1000 is a single-phase three-wire system, but the model of the electronic watt-hour meter 1000 is not particularly limited.

In the illustrated example, the power supply side terminal 100A (1S, 2S, 3S) to which the distribution line from the power supply facility is connected to the terminal 100, and the load side terminal to which the distribution line to the load in the consumer is connected. The parts 100B (1L, 2L, 3L) are arranged so as to face each other in the vertical direction. The power supply side terminal portion 100A and the load side terminal portion 100B have an insulating space 104 electrically insulated from each other by the partition wall portion 106 of the resin housing of the electronic watt-hour meter 1000. A terminal fitting 108 and a terminal screw 110 are arranged in each insulating space 104. For the connection between each terminal fitting 108 and the distribution line, for example, the distribution line is inserted and crimped into the cavity 122 of the crimp terminal 120 having the ring-shaped tip 118 as shown in FIG. 2, and the tip 118 of the crimp terminal 120 is inserted and crimped. Can be done by screwing the terminal screw 110 to the terminal fitting 108.

FIG. 3A is a schematic partial cross-sectional view showing the configuration of the terminal portion 100 in the insulating space 104, and shows the configuration when the electronic watt-hour meter (hereinafter, watt-hour meter) 1000 is viewed from the lower side of FIG. .. That is, in FIG. 3A, the upper side is the front side of the watt hour meter 1000, and the lower side is the back side. In the terminal portion 100, the terminal fitting 108 and the nut 124 are positioned and fixed in advance in the insulating space 104 between the adjacent partition walls 106 so that their respective openings (reference numerals omitted) are aligned. Specifically, the partition wall portion 106 forms a stepped portion 126 projecting into the insulating space 104, and the terminal fitting 108 is attached to the nut 124 arranged in the stepped portion 126. A crimp terminal 120 is arranged between the attached terminal screw 110 and the terminal fitting 108. In this way, the terminal screw 110 is tightened to the nut 124 via the crimp terminal 120 and the terminal fitting 108, whereby the crimp terminal 120 is configured to be connected to the terminal fitting 108. FIG. 3A shows the crimp terminal 120 before the terminal screw 110 is tightened. A recess 132 having a bottom surface 130 is formed on the lower side of the step portion 126. The recess 132 can receive the tip 111 of the shaft portion of the tightened terminal screw 110. In the figure, 128 indicates a washer, but the washer is not an essential component in the present embodiment.

In the first embodiment, the partition wall portion 106 that defines the insulating space 104 includes a protruding portion 107 that protrudes into the insulating space 104. In the illustrated example, the partition wall 106 includes a pair of protrusions 107 that are arranged in the insulating space 104 so as to face each other. However, the number of protrusions 107 is not particularly limited, and a single protrusion 107 may extend in the insulating space 104, or three or more protrusions 107 may be provided as required. Further, in the illustrated example, the protrusion 107 has a substantially triangular cross section, but may have a rectangular or semicircular cross section.

The protrusion 107 is provided on the side opposite to the nut 124 with respect to the terminal fitting 108. The protrusion 107 can project in a direction intersecting the axial direction of the terminal screw 110 or the axial direction of the opening of the terminal fitting 108 and the nut 124. Further, the protrusion 107 can extend to a position inside the outer edge 121 of the crimp terminal 120. The protrusion 107 can be crushed by the crimp terminal 120 in the tightening process of the terminal screw 110 described later. Here, crushing means destruction or deformation.

Next, the tightening process of the terminal screw 110 will be described with reference to FIGS. 3A to 3C. In the first embodiment, the tightening step can be performed in two steps. Specifically, the tightening step includes a temporary tightening step (first step) of tightening the terminal screw 110 to the nut 124 to a position where the crimp terminal 120 contacts the protrusion 107 (in other words, a temporary tightening position). A final tightening step (second step) of further tightening the temporarily tightened terminal screw 110 until the crimp terminal 120 comes into contact with the terminal fitting 108 is included. Here, "the crimp terminal 120 comes into contact with the terminal fitting 108" means a state in which the crimp terminal 120 and the terminal fitting 108 are brought into close contact with each other substantially without fear of heat generation due to an increase in contact resistance.

The final tightening process can be performed using a torque driver or a torque wrench, in which case the final tightening process ends when the terminal screw 110 is tightened to a specified torque value. In the final tightening step, the protrusion 107 is crushed by the crimp terminal 120.

First, as shown in FIG. 3A, the crimp terminal 120 is arranged in the insulating space 104. At this time, the crimp terminal 120 is arranged on the side opposite to the terminal fitting 108 with respect to the protrusion 107. Then, the terminal screw 110 is temporarily tightened to the nut 124 through the openings of the crimp terminal 120 and the terminal fitting 108. FIG. 3B shows a temporary tightening position of the terminal screw 110. In the temporary tightening, when the crimp terminal 120 comes into contact with the protrusion 107 by tightening the terminal screw 110, specifically, as shown in FIG. 3B, the crimp terminal 120 is the head of the terminal screw 110 (used by the washer 128). When it is held, it can be terminated when it is sandwiched by the washer 128) and the protrusion 107. Temporary tightening can be performed with, for example, a general electric screwdriver. At this time, as shown in FIG. 3B, the temporarily tightened terminal screw 110 is in a relatively loose state due to the presence of the protrusion 107.

After temporary tightening, final tightening is performed using, for example, a torque driver or a torque wrench. At this time, the protrusion 107 is crushed by the crimp terminal 120. As a result, the temporarily tightened terminal screw 110 can be further tightened, and the crimp terminal 120 can be connected to the terminal fitting 108. The final tightening can be completed when the terminal screw 110 is tightened to a specified torque value. FIG. 3C shows the final tightening position of the terminal screw 110. FIG. 3C shows a state in which the protrusion 107 is crushed.

As described above, in the watt-hour meter 1000 of the first embodiment, the terminal screw 110 can be tightened in two stages of the temporary tightening step and the final tightening step, and the temporary tightening position of the terminal screw 110 is intentionally loosened. Can be set to a large position. In the conventional watt hour meter, the tightened state of the terminal screw is confirmed by the operator touching the cable of the distribution line by hand or the like. Therefore, even if there is a slight looseness in the terminal screw, there is a risk that the tightening work will be completed without the operator noticing it. In the first embodiment, a predetermined temporary tightening position is set for the terminal screw 110 by the protrusion 107, and the looseness of the terminal screw 110 at the temporary tightening position is intentionally increased. As a result, the operator who has completed the temporary tightening work can surely notice the looseness of the terminal screw 110 when he / she touches the cable of the distribution line for confirmation. Therefore, the worker can always perform the final tightening work before completing the installation of the watt-hour meter. As a result, the operator can reliably tighten the terminal screw 110 to a specified torque value, and can satisfactorily connect the crimp terminal 120 and the terminal fitting 108. Therefore, it is possible to eliminate the risk that the temperature of the terminal portion 100 rises due to an insufficient tightening state and the watt-hour meter 1000 ignites.

The material, shape, and dimensions of the protrusion 107 are not particularly limited as long as the protrusion 107 can be crushed by tightening the terminal screw 110. As shown in the illustrated example, the protrusion 107 can be formed integrally with the partition 106, for example, with the same material as the partition 106 (for example, polycarbonate). Alternatively, the protrusion 107 may be formed separately from the partition 106 with a material different from that of the partition 106, for example, a material having appropriate elasticity so that it can be used repeatedly.

[Second Embodiment]
Next, the configuration of the terminal portion of the watt-hour meter according to the second embodiment will be described with reference to FIGS. 4A to 4C. The electronic watt-hour meter of the second embodiment may have the same configuration as the watt-hour meter 1000 of the first embodiment except for the configuration of the terminal portion described below.

Similar to the first embodiment, the watt hour meter of the second embodiment includes a terminal portion configured to connect the crimp terminal 120 to the terminal fitting 108. Therefore, the terminal portion includes the insulating space 104 defined by the partition wall portion 106 of the insulating housing, the terminal fitting 108 fixed in the insulating space 104, and the nut 124 fixed to the terminal fitting 108 in the insulating space 104. , A terminal screw 110 configured to be fastened to the nut 124 via a crimp terminal 120 and a terminal fitting 108.

In the second embodiment, the partition wall portion 106 includes a surface portion 140 instead of the protrusion portion 107 of the first embodiment. The surface portion 140 is provided on the same side as the nut 124 with respect to the terminal fitting 108, and is arranged at a position facing the tip 111 of the shaft portion of the terminal screw 110 in the axial direction. In the illustrated example, the surface portion 140 constitutes a portion of the support 142 provided in the recess 132 and formed separately from the partition wall portion 106. The support 142 or the surface 140 can come into contact with the tip 111 of the shaft of the terminal 110 and support it. In the illustrated example, the surface portion 140 has a convex shape protruding in the axial direction of the terminal screw 110. However, the surface portion 140 may be a flat surface or a concave surface as long as it can come into contact with the tip 111 of the shaft portion of the terminal portion 110. Further, the contact position between the surface portion 140 and the tip end 111 of the shaft portion of the terminal screw 110 is not particularly limited as long as the terminal screw 110 is held at a relatively large and loose position. For example, the convex surface portion 140 may be terminated within the opening of the nut 124. In this case, the terminal screw 110 and the surface portion 140 come into contact with each other in the opening of the nut 124. The surface portion 140 can be crushed by the tip 111 of the shaft portion of the terminal screw 110 in the tightening step of the second embodiment described later.

Next, the tightening step of the terminal screw 110 in the second embodiment will be described with reference to FIGS. 4A to 4C. Similar to the first embodiment, in the second embodiment, the tightening step can be performed in two steps. Specifically, the tightening step is a temporary tightening step of tightening the terminal screw 110 to the nut 124 to a position where the tip 111 of the shaft portion of the terminal screw 110 contacts the surface portion 140 (in other words, a temporary tightening position). The first step) and the final tightening step (second step) of further tightening the temporarily tightened terminal screw 110 to the nut 124 until the crimp terminal 120 comes into contact with the terminal fitting 108 are included. The final tightening process can be performed using a torque driver or a torque wrench, in which case the final tightening process ends when the terminal screw 110 is tightened to a specified torque value. In the final tightening step, the surface portion 140 is crushed by the tip 111 of the shaft portion of the terminal screw 110.

First, as shown in FIG. 4A, the crimp terminal 120 is arranged in the insulating space 104. Then, the terminal screw 110 is temporarily tightened to the nut 124 through the openings of the crimp terminal 120 and the terminal fitting 108. FIG. 4B shows a temporary tightening position of the terminal screw 110. As shown in FIG. 4B, the temporary tightening can be completed when the tip 111 of the shaft portion of the terminal screw 110 comes into contact with the surface portion 140 by tightening the terminal screw 110. Temporary tightening can be performed with, for example, a general electric screwdriver. At this time, as shown in FIG. 4B, the temporarily tightened terminal screw 110 is in a relatively loose state due to the presence of the surface portion 140.

After temporary tightening, final tightening is performed using, for example, a torque driver or a torque wrench. At this time, the surface portion 140 is crushed by the tip 111 of the shaft portion of the terminal screw 110. As a result, the temporarily tightened terminal screw 110 can be further tightened, and the crimp terminal 120 can be connected to the terminal fitting 108. The final tightening can be completed when the terminal screw 110 is tightened to a specified torque value. FIG. 4C shows the final tightening position of the terminal screw 110. FIG. 4C shows a state in which the surface portion 140 is crushed.

As described above, also in the watt-hour meter of the second embodiment, the terminal screw 110 can be tightened in two stages of the temporary tightening step and the final tightening step, and the temporary tightening position of the terminal screw 110 is intentionally loosened. Can be set to a large position. Therefore, the operator who has completed the temporary tightening work can surely notice the looseness of the terminal screw 110 when he / she touches the cable of the distribution line for confirmation. Therefore, there is no possibility that the operator completes the installation of the watt-hour meter without performing the final tightening work after the temporary tightening. The operator can securely tighten the terminal screw 110 to a specified torque value by the final tightening work, and can satisfactorily connect the crimp terminal 120 and the terminal fitting 108. Therefore, it is possible to eliminate the risk that the temperature of the terminal portion rises due to an insufficient tightening state and the watt hour meter ignites.

The material, shape, and dimensions of the surface portion 140 are not particularly limited as long as the surface portion 140 can be crushed by tightening the terminal screw 110. The surface portion 140 can be formed integrally with the partition wall portion 106, for example, with the same material as the partition wall portion 106. For example, the surface portion 140 may be formed by projecting the bottom surface 130 of the partition wall portion 106 toward the tip 111 of the terminal screw 110. Alternatively, as shown in the illustrated example, the surface portion 140 may be formed separately from the partition wall portion 106. In this case, the surface portion 140 may be formed of a material different from that of the partition wall portion 106, for example, a material having appropriate elasticity so that it can be used repeatedly.

Although the embodiments of the present invention have been described above, the embodiments of the invention described above are for facilitating the understanding of the present invention and do not limit the present invention. The present invention can be modified and improved without departing from the spirit thereof, and it goes without saying that the present invention includes an equivalent thereof. In addition, any combination or omission of the claims and the components described in the specification is possible within the range in which at least a part of the above-mentioned problems can be solved or at least a part of the effect is exhibited. Is.

The present invention includes the following aspects.
1. 1. A watt-hour meter equipped with a terminal portion configured to connect a crimp terminal to a terminal fitting.
The terminal part is
Insulated space defined by the partition wall of the insulated housing,
With terminal fittings fixed in an insulated space,
Nuts fixed to terminal fittings in an insulated space,
Terminal screws that are configured to be tightened to nuts via crimp terminals and terminal fittings,
Including
A watt-hour meter that is provided on the side opposite to the nut with respect to the terminal fitting and includes at least one crushable protrusion that protrudes into the insulating space.
2. Above 1. The watt-hour meter described in
A watt-hour meter whose protrusion extends to a position inside the outer edge of the crimp terminal so that it contacts the crimp terminal at the temporary tightening position of the terminal screw.
3. 3. Above 1. Or 2. The watt-hour meter described in
The partition wall is a watt hour meter that includes at least a pair of protrusions arranged in an insulated space facing each other.
4. A watt-hour meter equipped with a terminal portion configured to connect a crimp terminal to a terminal fitting.
The terminal part is
Insulated space defined by the partition wall of the insulated housing,
With terminal fittings fixed in an insulated space,
Nuts fixed to terminal fittings in an insulated space,
Terminal screws that are configured to be tightened to nuts via crimp terminals and terminal fittings,
Including
A watt-hour meter including a crushable surface portion provided on the same side as the nut with respect to the terminal fitting and located at a position facing the tip of the shaft portion of the terminal screw.
5. Above 4. The watt-hour meter described in
The watt hour meter is configured so that the surface part comes into contact with the tip of the shaft part of the terminal screw at the temporary tightening position of the terminal screw.
6. Above 4. Or 5. The watt-hour meter described in
The surface is a watt hour meter that is a convex surface that protrudes toward the tip of the shaft of the terminal screw.

The present invention can be widely applied to a watt-hour meter configured to connect a crimp terminal to a terminal fitting with a terminal screw.

100 Terminal part 100A Power supply side terminal part 100B Load side terminal part 104 Insulation space 106 Partition part 107 Protrusion part 108 Terminal metal fittings 110 Terminal screw 111 Tip 112 Liquid crystal display part 118 Tip part 120 Crimping terminal 121 Outer edge 122 Cavity part 124 Nut 126 Step part 128 Washer 130 Bottom 132 Recess 140 Surface 142 Support 1000 Electronic watt-hour meter

Claims (6)

A watt-hour meter equipped with a terminal portion configured to connect a crimp terminal to a terminal fitting.
The terminal part
Insulated space defined by the partition wall of the insulated housing,
The terminal fittings fixed in the insulated space and
A nut fixed to the terminal fitting in the insulating space,
A terminal screw configured to be fastened to the nut via a crimp terminal and the terminal fitting.
Including
A watt-hour meter including at least one crushable protrusion that is provided on the side of the terminal fitting opposite to the nut and protrudes into the insulating space. The watt hour meter according to claim 1.
A watt-hour meter in which the protrusion extends to a position inside the outer edge of the crimp terminal so as to come into contact with the crimp terminal at the temporarily tightened position of the terminal screw. The watt-hour meter according to claim 1 or 2.
A watt hour meter including at least a pair of protrusions arranged in the insulating space so as to face each other. A watt-hour meter equipped with a terminal portion configured to connect a crimp terminal to a terminal fitting.
The terminal part
Insulated space defined by the partition wall of the insulated housing,
The terminal fittings fixed in the insulated space and
A nut fixed to the terminal fitting in the insulating space,
A terminal screw configured to be fastened to the nut via a crimp terminal and the terminal fitting.
Including
A watt-hour meter including a crushable surface portion provided on the same side as the nut with respect to the terminal fitting and arranged at a position facing the tip of the shaft portion of the terminal screw. The watt hour meter according to claim 4.
The watt hour meter is configured such that the surface portion comes into contact with the tip of the shaft portion of the terminal screw at a temporary tightening position of the terminal screw. The watt hour meter according to claim 4 or 5.
The watt hour meter is a surface portion that is a convex surface that protrudes toward the tip of the shaft portion of the terminal screw.

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