JPS63102135A - Thermal type overcurrent relay - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is mainly used as an overcurrent protection relay in electromagnetic switches used for starting and stopping rust-conducting motors, and is usually called a thermal relay. This paper relates to improvements to thermal overcurrent relays.

[Conventional technology]

Figure 3 is a front sectional view of a conventional thermal overcurrent relay;
The drawings are a sectional view taken along the line AA in FIG. 3, FIG. 5 is a sectional view taken along the same line B-B, and FIG. In the figure, (1) is a case, (2 is a cover), and (3) is a plurality of bimetals provided corresponding to each phase of the detected circuit, each of which connects the ends of the detected circuit where current flows and generates heat. It is heated by the heating wire (4), which is a heating element connected to the conductor, and curves as shown by the broken line in the figure in response to the magnitude of the detected circuit current flowing through the heating wire (4).(5) is fixed. One end of the bimetal (3) is joined and fixed to the tongue (5a) by a terminal.

This fixed terminal (5) is fixed to the case (1) by a tightening screw (6), and one end of the fixed terminal (5) is connected to an external circuit (main circuit).
A terminal screw (7) for connection is attached. (8) is an interlocking plate that transmits the deformation motion of the bimetal (3), and is arranged so as to come into contact with the tips of various bimetals (3), and the other end presses the lower end of the temperature-compensating bimetal (9). There is. (+[) is the operating lever, which is a temperature compensated bimetallic (9
) is fixed to the upper end and rotatably arranged around the shaft (1υ), and both ends of this shaft (1υ are supported by lever supports), and this lever support is attached to the inner side of the lever shape. (12a) is in contact with and supported by the edge part (la) of the case, the first tongue part (12b) is pressed against and in contact with the adjustment screw a, and the second tongue part (12C) is in contact with the plate. Spring α4
) so that it receives a biasing force to the left.

Therefore, by rotating the adjustment knob (5) placed over the adjustment screw a [phase], the lever support (support) can be adjusted.
rotates around the edge portion (la), and the shaft (1υ) changes its position approximately in the left-right direction to change and adjust the operating current.

(16) is a movable terminal, which is formed from a thin metal plate having spring properties and conductivity, and is punched into a shape consisting of an inner beam part (16a) and an outer beam part (16b) as shown in FIG. A U-shaped plate spring 07) is engaged between the tip of the inner beam (llia) and the outer beam (16b) so as to press and bias the contact portion (16c) of the movable contactor. A normally closed contact is formed opposite the closed fixed terminal marked 0. The lower end (16e) of the movable contact is fixed to the normally closed movable terminal αΦ, and the normally closed movable terminal (16e) is fixed to the normally closed movable terminal αΦ.
The support (support) is fixed to the case (1) with a screw holder,
The inner beam (16a) of the movable contact is inserted into a T-shaped hole provided at the tip of the operating lever QO. The upper end (16f) of the movable contact is engaged with a groove (21a) provided at the left end of the cross bar 21), and is guided by the case (1) so that it can move in parallel in the left-right direction.

(A) and (C) are Kyoto contact terminals, - is a normally open fixed contact,
(C) is a normally open movable contact, and these contacts (2) and (C) are made of a thin metal plate with spring properties and conductivity, and are caulked to the contact terminals (A) and (To) between the two terminals. The back side (right side) of the tip of the normally open movable contactor comes into contact with the protruding piece (21g) of the crossbar t2υ. □□□ The beam set bar is slidably supported by the case (1) so that it can move up and down, and is biased by the upward pressing force of the return spring fin by the edge part (28c), and at the upper limit stopping point. The vertical surface portion (4ad) presses against the curved portion (24a) of the back surface of the normally open movable contact.

Further, the slope portion (26a) moves the curved portion (24a) to the right by suppressing downward movement of the reset bar (to). (26b) is a locking hole provided in the reset bar holder.If you want to change to the automatic return type, push down the reset bar holder and slide the switching plate (support) to the left in Figure 3. Insert into the hole (26b),
The reset bar is locked to return upward.

In the conventional thermal overcurrent relay configured as described above, the bimetal (3) in Figure 3 is bent as shown by the broken line in the figure due to heating by the main circuit current flowing through the heating wire (4). However, when an overcurrent condition occurs, the main circuit current increases, and the bimetal (3) deforms even more. For this purpose, the interlocking plate (8) is bimetallic (3)
The connecting body between the temperature compensating bimetal (9) and the actuating lever Cl0) is moved to the left in the figure.
The movable contact (
The inner beam (16a) also moves to the right.

Next, the force direction of the biasing force of the U-shaped leaf spring α7) is
When the movable contact (16) reaches the dead center caused by the force that tries to return to its original position, the movable contact (16) rapidly reverses itself, and in the same figure, the outer beam (16b) moves to the left and the inner The beam part (IBa) jumps to the right. Therefore, the contact part (16c) and the normally closed fixed terminal 08) are brought into contact, and the normally closed contact that has maintained electrical continuity is opened, and the crossbar 121) is moved to the outside. The tip (16f) of the beam (16b) moves to the left, and the protruding piece (21g) deforms the normally open movable contact (c) to the left. For this reason, the normally open movable contact (2) comes into contact with the normally open fixed contact (2), and the normally closed contact becomes in the ON state. At this time, the normally closed contact is such that the pressure of the U-shaped leaf spring (17) presses the contact via the movable contact (16) and the crossbar Cυ, creating contact pressure that closes the contact. It turns out.

When the normally closed contact is turned off, the normally closed contact is connected in series to the coil circuit of an electromagnetic contactor (not shown) that switches on and off the main circuit current, so the main circuit opens when the current is A. For example, to protect induction motors from damage due to overload. Also, the normally closed contacts are turned on at the same time, so
If you connect an alarm buzzer or lamp in series with this contact,
An overcurrent relay is activated by an overcurrent (overload) and can indicate that the main circuit is open.

Next, after the main circuit current is cut off and the bimetal (3) returns to its original state, in order to restore the normally open and normally closed contacts described above, push the reset bar downward by manual operation from the outside. When the slope portion (26a) returns to the curved portion (24) of the normally open fixed contact (A) while resisting the reaction force of the spring (5),
Press to the right of a) and press the normally open movable contact (
a) to move the tip (16f) of the movable contact by pressing the protrusion (26g) of the crossbar 4 in the right direction,
Once the reversal point is crossed, the movable contacts (one of them) quickly recovers and completes the return movement.

(Problems to be Solved by the Invention) Conventional thermal overcurrent relays operate a reversing mechanism by excessive displacement of the bimetal caused by overcurrent as described above, and the normally closed contacts and normally closed contacts of the control circuit operate. The contacts are opening and closing. For this reason, a mechanical contact mechanism is required, which may result in unstable operation, and vibrations, shocks, etc. are generated during operation, resulting in problems such as a short lifespan of each contact mechanism.

The present invention was made in order to solve the above problems, and it enables the signal circuit of a thermal overcurrent relay to operate stably,
The purpose of this invention is to obtain a thermal overcurrent relay that can improve current characteristics.

[Means for solving problems]

In order to achieve the above object, the present invention provides a pressure sensor that detects the operation of a bimetal, and uses the output of this pressure sensor to invert the signal circuit of an overcurrent relay.

(Function) The displacement of the bimetal is applied to the pressure sensor, and when the pressure exceeds a certain value, the signal circuit is reversed.

〔Example〕

FIG. 1 is a sectional view of an embodiment of the invention, and FIG. 2 is a block diagram for explaining the invention in detail. Note that the same or equivalent parts as in the conventional example shown in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

In both figures, (51) is a pressure sensor attached to the case (1), and its actuator is in contact with the tip of the operating lever αQ. (52) is a pressure sensor (51)
This is an amplifier that amplifies the output of. (53) is a beam set switch, (57) is a trip switch, (54) is an inversion circuit that inverts the signal circuit (X), and pressure sensor (51) is an inversion circuit that inverts the signal circuit (X).
) detects a predetermined pressure, its output is sent to an amplifier (52).
and the amplified output is applied. Signal circuit (
X) is a non-contact relay that normally uses a semiconductor element, and is normally closed and is turned off by the inversion signal from the inversion circuit (54).
There is a normally closed circuit (×1), which is always closed, and a normally open circuit (×
2) It consists of.

(55) is a reset circuit that resets the above-mentioned inverted signal circuit (X), and a signal from this circuit is used to reset the normally closed circuit (X).
1) is closed, and the normally open circuit (×2) is opened.

This reset circuit (55) is a reset switch (53)
The above operation is performed with the signal from the selection switch (5
If 5b) is closed and the automatic reset function is selected,
The pressure sensor (51) detects a predetermined pressure and activates the inversion circuit (
54) is activated, it is automatically reset after a predetermined time set in the delay circuit (55a).

Furthermore, the trip switch (57) is a switch that manually reverses the signal circuit (X) in order to open the electromagnetic switch or the like when an abnormality occurs. ) is reversed.

Next, the present invention configured as described above will be explained in detail. First, in the initial state, the signal circuit (X) is in a reset state, the normally closed circuit (x1) is closed, and the normally open circuit (x1) is closed.
×2) is in an open state. Now, if the current flowing in the main circuit becomes excessive and exceeds the set value, the bimetal (
3) becomes excessive and moves the interlocking plate (8) to the left in the figure. This allows the temperature-compensating bimetal (9) to move from the shaft (
11), and the tip of the operating lever OQ connected thereto presses the actuator of the pressure sensor (51).

This increases the pressure applied to the pressure sensor (51),
Its output also increases. The output of the pressure sensor (51) is amplified by the amplifier (52), and when the output exceeds a certain value, the output of the pressure sensor (51) is amplified by the inverting circuit (
54) works, the signal circuit (X) is inverted and becomes a normally closed circuit (
x1) is turned OFF and protects the main circuit by cutting off the main circuit when the motor etc. is overloaded. If the selection switch (ssb) is set to automatic, the output of the pressure sensor (51) is simultaneously applied to the delay circuit (55a) via the amplifier (52), and after a certain period of time has elapsed, the output of the pressure sensor (51) is applied to the delay circuit (55a).
) and reset the signal circuit.

Next, press the reset button (56) or trip button (5
8) to operate the reset switch (53) or trip switch (57), the signal circuit (X) can be manually inverted and reset.

(Effects of the Invention) As is clear from the above description, the present invention does not use a conventional mechanical contact mechanism, but instead uses the output of the pressure sensor to electrically invert the signal circuit. Remarkable effects like this can be obtained.

(1) Stabilize the control circuit operating characteristics after overcurrent detection.

(2) Since there is no reversing mechanism, spring mechanism, etc., operation is reliable, and vibration resistance and impact resistance are improved.

(3) Since mechanical contacts are not used, non-contact relays can be used.

(4) By changing the pressure detection level, characteristics with good adjustment accuracy of set values can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a block diagram for explaining the invention in detail, Fig. 3 is a sectional view showing an example of a conventional thermal overcurrent relay, and Fig. 4. -FIG. 6 are sectional views taken along lines AA, BB, and CC in FIG. 3, respectively. 1: Case, 3: Bimetal, 8: Interlocking plate, 9: Temperature compensation bimetal, 10: Operating lever, 11: Shaft, 51: Pressure sensor, 52: Amplifier, 53: Reset switch, 5
4: inversion circuit, 55: reset circuit, 55a: delay circuit, ssb two selection switch, 56: reset button, 57
: Trip switch, 58 nit trip button, X: Signal circuit, xI: Normally closed circuit, x2: Normally open circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Patent attorney Tadashi Sato 3rd rg: J + 6" 1 cho'Q talented touch 21.70 snow ＼° - 24, τ fight fixation with hand angle 25: attached 5 8 Hi υ years old !Touch now 26, Rikuso upper bar figure 6

Claims (5)

[Claims] (1) A thermal overcurrent relay that includes a heating element through which a current to be detected flows and a bimetal heated by the heating element, and detects when the current to be detected becomes an overcurrent due to displacement of the bimetal, A pressure sensor that detects the pressing force due to the displacement of the bimetal, and a first circuit that reverses the normally closed circuit and opens the circuit when the pressure sensor detects a predetermined pressure.
A thermal overcurrent relay characterized by being equipped with a signal circuit. (2) The thermal overcurrent relay according to claim 1, further comprising a second signal circuit whose normally open circuit is closed when the pressure sensor detects a predetermined pressure. (3) Claims 1 or 2 further include a reset circuit including a delay element that resets the signal circuit after a predetermined period of time has passed after the signal open circuit is reversed.
Thermal overcurrent relay described in . (4) The thermal overcurrent relay according to claim 1 or 2, further comprising a reset button for manually resetting the inverted signal circuit. (5) Claims 1 to 4 include a trip button that manually reverses the signal circuit.
Thermal overcurrent relay according to any of paragraphs.