JP4540774B2 - Terminal block - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a terminal block in which the temperature of the terminal fitting can be detected by a temperature sensor, and in particular, the temperature of the terminal fitting that becomes the reference temperature of the thermocouple connected to the terminal fitting can be accurately detected. The present invention relates to a terminal block capable of improving measurement accuracy.
[0002]
[Prior art]
In order to take in a control device a measurement signal drawn from a measurement object such as a production facility by an external conductor, a terminal block for connecting the external conductor is used as an input unit of the controller. As an example of such a terminal block, there is an inner terminal block that has no electrical conductive part exposed on the surface of the terminal block and is excellent in electrical insulation. The inner terminal block accommodates multiple terminal fittings in an aligned state inside the main body, and for each terminal fitting, an external conductor insertion port and a screw that constitutes a mechanism for bringing the external conducting wire into contact with the terminal fitting inside the main body. Insert the external conductor with the tip covering removed from the external conductor insertion slot, and insert the screw into the terminal metal inside the terminal metal. The external conductor is pressed against the terminal metal to make an electrical connection between the external conductor and the terminal metal.
[0003]
One of the measurement signals extracted from the measurement target is a temperature signal indicating the temperature of the measurement target. In general, the temperature of a measurement target is often measured by a thermocouple, and in this case, the thermoelectromotive force generated in the thermocouple corresponds to a temperature signal as a measurement signal. Temperature measurement with a thermocouple is performed by placing the contact on the measurement target side as the measurement target and measuring the temperature and thermoelectromotive force of the contact on the reference temperature side. In order to keep the error small, the reference temperature must be accurately measured.
[0004]
The reference temperature is measured by directly measuring the temperature of the terminal fitting with a temperature sensor such as a thermistor. However, since the internal temperature of the control device varies from place to place according to the installation position of the heat-generating parts such as the power supply, the temperature of the terminal bracket of the terminal block attached to the input part of the control device also varies from place to place. Yes. In addition, when the terminal block is long, the temperature of each terminal fitting may be different in one terminal block. For this reason, in order to perform accurate reference temperature measurement, it is necessary to arrange the temperature sensor as close as possible to the terminal fitting on the reference temperature side.
[0005]
As such a conventional technique, there is an invention disclosed in Japanese Utility Model Laid-Open No. 5-34540. In this prior art, when using a thermocouple, a U-shaped groove is formed in the terminal fitting at the end of the terminal block, and a temperature sensor is housed in this groove to measure the temperature of the terminal fitting.
[0006]
As another prior art, there is an invention disclosed in Japanese Utility Model Laid-Open No. 5-36329. In this prior art, when a thermocouple is used, a temperature measuring unit for directly measuring the temperature of the terminal fitting is attached.
[0007]
[Problems to be solved by the invention]
However, since the former prior art measures the temperature of the terminal fitting located at the end of the terminal block, if the temperature of the plurality of terminal fittings differs depending on the location, the temperature of the terminal fitting other than the end is set. Measurement with high accuracy is not possible, and in order to perform measurement with high accuracy, U-shaped grooves must be formed in all the terminal fittings, resulting in a problem that the terminal block becomes large.
[0008]
In addition, the sensor part of a temperature sensor such as a thermistor is often sealed with resin, but some of the sensor part has a non-uniform shape. Therefore, depending on variations in sensor shape, there is a problem that the contact between the terminal fitting and the temperature sensor is not sufficient when the temperature sensor is housed in the U-shaped groove.
[0009]
Furthermore, in the latter prior art, it is possible to individually measure the temperature of a plurality of terminal fittings, but because the configuration is equipped with a temperature measurement unit, the configuration is complicated and the terminal block is large. There is a point.
[0010]
Here, the increase in the size of the terminal block leads to a loss of compatibility with other normal terminal blocks, and there is also a problem that versatility as an input unit of the control device is lost.
The present invention has been made in view of the above points, and is a terminal block capable of accurately measuring the temperature of a terminal fitting with a simple configuration without increasing the size as compared with a conventional terminal block. The purpose is to provide.
[0011]
[Means for Solving the Problems]
In the present invention, in order to solve the above problems, so as to be electrically connected by being pressed by the action of a screw screwed through the external conductor insertion opening than the inserted external conductor line sleep Flip insertion opening respectively in it the terminal board that was retract and in alignment plurality of terminals gold tool the inside of the case that, for detecting the temperature of the terminal fitting is located outside of the terminal fitting is the external conductors inside is pressed against There is provided a terminal block comprising: a temperature sensor; and a leaf spring formed on the case and having an elastic force to press the temperature sensor against the terminal fitting .
[0012]
Here, the leaf spring presses the temperature sensor against the outer surface of the terminal fitting due to its elastic force, and the external conductor is brought into contact with the inner surface of the terminal fitting against which the temperature sensor is pressed. The temperature of the contacted terminal fitting will be measured directly.
[0013]
Further, the leaf spring may have a curved portion in the center, the temperature sensor terminal block, characterized in that disposed inside the curved portion is provided.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a front view of the terminal block 1 in the present embodiment , and FIG. 1 is a cross-sectional view taken along line AA in the terminal block 1 of FIG.
[0015]
The terminal block 1 includes an external conductor insertion port 2Aa to 2Ai (only 2Ah is shown in FIG. 1 ) , a screw insertion port 2Ba to 2Bi (only 2Bh is shown in FIG. 1) , and a case 2 having leaf springs 2a to 2i. second terminal fittings 4a-4i are housed inside, the temperature sensor 3a for measuring the terminal fittings 4a-4i, is configured 3b, and the bottom cover 5 for housing the terminal fittings 4a-4i inside of the case 2 A plurality of external conductors 10a to 10i are attached. Here, the leaf spring 2a~2i that having a resilient force, to a portion of the case 2 may be formed by slitting, using a mold that can slit when forming the case 2 it may be formed integrally by molding Te. Further, the terminal metal fitting 4h shown in FIG. 1 pressurizes the pendulum 4hc by being screwed into the terminal portion 4ha, the screwing portion 4hb, the pendulum 4hc for fixing the external conducting wire 10h, and the screwing portion 4hb. It is comprised by the screw 4hd. The other terminal fittings 4a to 4g and 4i have the same configuration as the terminal fitting 4h.
[0016]
As a material of the case 2 and the bottom cover 5, nylon or the like can be used without particular limitation as long as it has insulating characteristics and has a certain degree of elasticity. About the terminal part 4ha and the screwing part 4hb, what has high electroconductivity, such as copper and copper alloy prescribed | regulated by JIS, can be used. Pendulum 4HC, for screw Reserved, can be used without particular limitations as long as the material with the degree of mechanical strength and resistance to corrosion is not deformed by pressure during screwing. The temperature sensors 3a and 3b can be used without particular limitation as long as they exhibit stable detection characteristics within a certain temperature use range. As such, a thermistor that can be used in a temperature range of about −60 ° C. to 150 ° C. is preferable. This temperature sensor is inserted between the terminal portion and the leaf spring as necessary. The thermocouple installed on the measuring object can be used without particular limitation, such as a combination of nickel / chromium and nickel / aluminum, a combination of nickel / chromium and constantan, and a combination of iron and constantan. .
[0017]
Next, the arrangement of the components constituting the terminal block 1 will be described.
As shown in FIG. 1, the terminal fitting 4 h is surrounded and held by the case 2 and the bottom cover 5.
[0018]
A screwing portion 4hb is disposed on the upper portion of the terminal portion 4ha, and the pendulum 4hc is held so as to be rotatable about its fulcrum 4he. A screw hole is formed in the screwing portion 4hb, and the screw 4hd is screwed into the screw hole of the screwing portion 4hb from the screw insertion port 2Bb of the case 2. The screw 4hd screwed in reaches the pendulum 4hc and pressurizes the pendulum 4hc. The pressurized pendulum 4hc rotates around the fulcrum 4he and sandwiches the external conducting wire 10h inserted between the terminal portion 4ha, whereby the external conducting wire 10h is fixed to the terminal fitting 4h. Here, when the external conducting wire 10h is a part of a thermocouple, the contact between the external conducting wire 10h and the terminal portion 4ha becomes the contact 10ha on the reference temperature side of the thermocouple.
[0019]
The leaf spring 2b of the case 2 has a curved shape, and is arranged so that the inside of the curved shape faces the side surface of the terminal portion 4ha of the terminal fitting 4h. Temperature sensor 3b is that the tip is the sensor unit is disposed between the side surface of the inner terminal portion 4ha curved shape of the leaf spring 2 h, pressed against the side surface of the terminal portion 4ha by the elastic force of the leaf spring 2h Fixed by. At that time, it is desirable that the temperature sensor 3b is disposed at a position as close as possible to the contact 10ha on the reference temperature side of the external conductor (thermocouple) 10h.
[0020]
FIG. 3 is an assembly diagram illustrating a state in which the terminal fitting 4 h and the temperature sensor 3 b are accommodated in the case 2. Inside the case 2 is divided into a plurality of regions, the terminal fitting 4a~4i is received in each divided region. In FIG. 3, only the terminal fitting 4h is shown to simplify the drawing.
[0021]
When the terminal fittings 4 a to 4 i are stored in the case 2, the bottom cover 5 is attached to the bottom surface of the case 2, and the terminal fittings 4 a to 4 i are held inside the case 2.
When the external conductors 10b and 10h are part of a thermocouple, temperature sensors 3a and 3b are disposed inside the leaf springs 2b and 2h of the case 2. In FIG. 3, only the temperature sensor 3b is shown for the sake of simplicity.
[0022]
FIG. 4 is a conceptual diagram showing the principle of temperature measurement using a thermocouple.
As shown in FIG. 4, the measurement object 6 is in contact with the junction of the external conductors 10h and 10i constituting the thermocouple (contact on the measurement object side). The other end of the external conducting wire 10h is connected to the terminal fittings 4h and 4i through a reference temperature side contact 10ha and the other end of the external conducting wire 10i through a contact 10ia (not shown) . Further, the temperature sensor 3b is in contact with the terminal fitting 4h. Output terminals of the terminal fittings 4 h and 4 i and the temperature sensor 3 b are connected to the signal processing circuit 7.
[0023]
Next, the temperature measurement operation of the terminal block 1 will be described with reference to FIGS.
First, the contact on the measurement object side of the external conductors 10 h and 10 i constituting the thermocouple is arranged on the measurement object 6. Thereby, the heat of the measuring object 6 is transmitted to the contact on the measurement object side of the external conductors 10h and 10i, and the temperature of the contact on the measurement object side in the external conductors 10h and 10i changes. Thereby, a temperature difference arises between the contact on the measurement object side of the external conductors 10h and 10i and the contact 10ha and 10ia on the reference temperature side, and the thermoelectromotive force caused by this temperature difference causes the contact between the contacts 10ha and 10ia. A potential difference V is generated between them. This potential difference V is read into the signal processing circuit 7.
[0024]
Further, the temperature of the contact 10ha on the reference temperature side is pressed by the leaf spring 2h, detected by the temperature sensor 3b disposed in the vicinity of the contact 10ha, and the detection result is also read into the signal processing circuit 7. The signal processing circuit 7 that has read the potential difference V and the reference temperature calculates the temperature of the measuring object 6 based on the potential difference V and the reference temperature.
[0025]
In the present embodiment , the terminal fittings are arranged in one row inside the terminal block, but the terminal fittings may be arranged in two or more rows.
In this embodiment, the case where two temperature sensors are arranged for one terminal block has been described. However, the number and arrangement of temperature sensors are not limited to those in this embodiment, and depend on the measurement target. Any number can be placed at any location.
[0026]
If the location where the temperature sensor is to be arranged is determined in advance, the leaf spring may be formed only at the location where the temperature sensor is arranged, instead of providing the leaf spring on the entire terminal block.
[0027]
【The invention's effect】
As described above, in the present invention , a leaf spring having elastic force is formed in the case, and the temperature sensor is pressed against the side surface of the terminal metal fitting by the leaf spring , so that the temperature sensor is disposed inside the case. There is no need to provide a new space, and even when a temperature sensor is arranged, the size can be the same as that of a conventional terminal block. Thereby, it can be used also as a terminal block which does not incorporate a temperature sensor, and can be provided as a normal standard product with a small size and low cost.
[0028]
Further, since the temperature sensor is pressed against the side surface of the terminal fitting by the leaf spring formed on the case, the temperature sensor can be easily attached from the outside of the case.
[0029]
Further, the leaf spring has a curved shape central portion medium, since the sensor portion of the temperature sensor was pushed against the inner side of the curved portion of the leaf spring on the side surface of the terminal fitting, even when the sensor shape is not uniform The temperature sensor can be disposed close to the contact on the reference temperature side of the thermocouple.
[0030]
In addition, the terminal block according to the present invention is a highly accurate, downsized, low-cost terminal block because there are few exposed metal parts, so there is little influence of outside air temperature and there is no need to add a cover or the like. it can.
[Brief description of the drawings]
1 is a cross-sectional view taken along line AA in the terminal block of FIG. 2;
FIG. 2 is a front view of a terminal block according to the present invention.
FIG. 3 is an assembly diagram illustrating a state in which a terminal fitting and a temperature sensor are housed in a case.
FIG. 4 is a conceptual diagram showing the principle of temperature measurement using a thermocouple.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Terminal block 2 Case 2a- 2i Leaf spring 3a, 3b Temperature sensor 4a-4i Terminal metal fitting 4hc Pendulum 5 Bottom cover 6 Measurement object 7 Signal processing circuit 10a-10i External conductor

Claims (2)

Inside the case a plurality of terminals gold instrument to which is to be electrically connected by the respective pushed against the action of a screw screwed through a Flip insertion opening sleep external guide wire inserted from the outside conductor insertion opening in a terminal block in alignment are retract and,
A temperature sensor disposed on the outside of the terminal fitting, on which the external conductor is pressed, and detecting the temperature of the terminal fitting;
A leaf spring formed on the case and having an elastic force to press the temperature sensor against the terminal fitting;
Terminal block, characterized in that it comprises. 2. The terminal block according to claim 1, wherein the leaf spring has a curved shape in the vicinity of a position where the temperature sensor is pressed against the terminal fitting, and fixes the temperature sensor .

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