WO2021182119A1

WO2021182119A1 - Level switch

Info

Publication number: WO2021182119A1
Application number: PCT/JP2021/007083
Authority: WO
Inventors: 晋平福井
Original assignee: 東和制電工業株式会社
Priority date: 2020-03-12
Filing date: 2021-02-25
Publication date: 2021-09-16
Also published as: JP6831139B1; JP2021145467A

Abstract

The objective of the present invention is to provide a level switch with which a voltage supply to a motor can be reliably and completely interrupted when a deposit is detected, without configuring a suicide circuit. If rotation of a blade 5 and a shaft 4A is restricted due to the presence of a deposit, a motor 4 spins about the shaft 4A, and a switch operating rod 4B applies a pressing force to an actuator unit 6A of a microswitch 6. By means of this pressing force, the microswitch 6 outputs a second signal S2 indicating a transition from an ON state to an OFF state to a delay circuit 7, and the delay circuit 7 outputs a third signal S3 at a time point at which a delay time α has elapsed from the time at which the second signal S2 was received. A control circuit 9 outputs to a semiconductor element 10 a fourth signal S4 at a level causing the semiconductor element 10 to switch from an ON state to an OFF state. The semiconductor element 10 switches to the OFF state, thereby reliably and completely interrupting the application to the motor 4 of a first signal S1 which imparts a supply voltage to the motor 4.

Description

Level switch

The present invention relates to the control of a paddle type (rotary type) level switch.

Conventionally, various level switches including microswitches have been proposed (see, for example, Patent Documents 1, 2 and 3).

In the paddle type (rotary type) level switch, a "suicide circuit" is adopted as a circuit that instantly turns off the power supply of the motor when a measured object such as powder or granules or deposits is detected. Has been done. Here, FIG. 1 is a block diagram schematically showing a configuration of a suicide circuit 100A of a conventional paddle type (rotary type) level switch. For convenience of understanding, FIG. 1B schematically shows a side view of the motor 4. When the flat plate-shaped blade 5 provided at one end of the shaft 4A of the motor 4 and rotating in the R direction together with the shaft 4A comes into contact with a measurement object such as powder and begins to be buried, the rotational movement of the blade 5 is measured as described above. It is restrained or deterred by the existence of an object. On the other hand, the supply voltage is still applied to the motor 4 from the commercial power supply 2. Therefore, in response to the suppression of the rotation of the shaft 4A of the motor 4, the motor 4 rotates around the shaft 4A as a central axis. The switch actuating rod 4B attached to and arranged on the portion of the motor 4 on the opposite side of the blade 5 in conjunction with the rotation movement of the motor 4 has a trajectory that draws an arc around the shaft 4A. The switch operating rod 4B abuts on the actuator portion 6A of the microswitch 6 and pushes the portion 6A. In response to such pressure, the microswitch 6 instantly cuts off the current from the commercial power source 2. In this way, when the presence of the object to be measured is detected, the motor 4 operates itself by closing the circuit system of the commercial power source 2 which is the power supply by itself through the mechanical operation in the microswitch 6. Will be stopped instantly. Therefore, the power supply circuit of the level switch is referred to as a suicide circuit 100A as described above.

JP-A-2002-340655 Utility Model Registration No. 3224683 Japanese Unexamined Patent Publication No. 2001-31164 Japanese Unexamined Patent Publication No. 11-316019 Japanese Unexamined Patent Publication No. 2006-253092

Microswitches with various configurations are on the market depending on the manufacturer. Therefore, when using a microswitch having a certain configuration, the microswitch is instantly completed depending on the force or distance at which the switch operating rod of the motor pushes the actuator portion of the microswitch when the object to be measured is detected. An unstable operation may occur in which the microswitch repeats between the OFF state and the ON state without shifting to the OFF state. Due to the occurrence of such unstable operation, the current flowing from the power supply voltage to the motor is not completely cut off when the object to be measured is detected.

Here, FIG. 2 is a diagram schematically showing an unstable region USR in which such unstable operation of the microswitch 6 occurs. In FIG. 2, at the stage before the detection of the measured object, the switch operating rod of the motor is not in contact with the actuator portion, and the pressing F from the actuator portion of the micro switch 6 is not applied, so that one end is fixed. The movable contact T4 fixed to the other end of the conductive tension spring 6B fixed to the end T1 is electrically connected to one fixed contact T2. In this state, a current is flowing from the power supply voltage to the motor, and the blades of the motor are rotating. On the other hand, when the rotational movement of the blades of the motor is stopped and the object to be measured is detected, the switch operating rod linked to the rotation of the motor around the shaft instantly comes into contact with the actuator portion and the switch operating rod is concerned. Presses the actuator section of the microswitch 6 to apply pressure F to the actuator section. As a result, the conductive tension spring 6B in the microswitch 6 is instantly deformed, and the movable contact T4 is instantly moved away from one fixed contact T2 to the other fixed contact T3 facing the other.

However, depending on the internal configuration of the microswitch 6, even if the pressing F is applied to the conductive tension spring 6B, the movable contact T4 does not completely move to the other fixed contact T3, and the inside of the unstable region USR in the middle thereof. Then, a repetitive operation (chattering) of the OFF state / ON state occurs in which the one fixed contact T2 is separated from the one fixed contact T2 and is contacted with the one fixed contact T2. When such a chattering phenomenon occurs, the voltage supplied from the commercial power supply to the motor is not completely turned off, and the supply voltage is continuously in the OFF state / ON state repeatedly. .. As a result, wear of the movable contact T4 and one of the fixed contacts T2 may occur. Further, the movable contact T4 of the conductive tension spring 6B may stop in the unstable region USR where the microswitch 6 is not securely pushed. The magnitude of this unstable region USR changes according to the lot of the microswitch 6. In such a case, an arc is continuously generated between one fixed contact T2 and the movable contact T4, and as a result, both contacts T2 and T4 are worn by the arc, resulting in a conduction failure. There is. It can be said that this problem is a defect factor associated with the suicide circuit in which the motor tries to cut off the power supply voltage by itself in response to the mechanical ON / OFF switching operation inside the microswitch. Further, such a problem also occurs when a suicide circuit is similarly configured by using another switch component instead of the micro switch, for example, a switch component such as a relay or a photocoupler. Is.

(Purpose of Invention)
The present invention has been made in view of the problem of the occurrence of such a continuity failure, and its main purpose is regardless of the configuration and lot of switch parts (eg, microswitches) used, and The point is to provide a level switch that can reliably and completely turn off the power supply of the motor when the object to be measured is detected without forming a suicide circuit.

The level switch according to the subject of the present invention is at a time when a predetermined delay time has elapsed from the first time when the motor shifts from the ON state to the OFF state due to the rotation of the motor around the shaft when the blades are restrained. It is provided with an electronic circuit that electrically cuts off the power supply voltage applied to the motor, and the electronic circuit shifts from the ON state to the OFF state in the electric system of the electronic circuit. The electronic circuit includes only one switch unit for detecting the first time point, and the electronic circuit responds to the detection signal of the first time point output by the only one switch unit in the electric system. It is characterized in that the power supply voltage of the motor is electrically cut off at a time when the motor is electrically delayed by the predetermined delay time from the first time point.

The level switch according to the subject of the present invention can reliably and completely turn off the power supply of the motor when the object to be measured is detected without forming a suicide circuit.
Hereinafter, various realizations of the present invention will be described in detail with reference to the accompanying drawings, together with their effects and advantages.

It is a block diagram which shows typically the structure of the suicide circuit of the conventional level switch. It is a figure which shows typically the unstable region of the microswitch used in a level switch. It is a block diagram which shows typically the structure of the level switch which concerns on Embodiment 1 of this invention.

(Embodiment 1)
<Core of level switch>
The level switch according to the present embodiment electrically controls the switching of the supply power supply of the motor of the level switch after forming a delay circuit by an electronic circuit without forming a suicide circuit.

That is, the "electronic circuit" of this level switch is predetermined from the first time when the motor shifts from the ON state to the OFF state due to the rotation of the motor around the shaft when the blades are restrained (at the time of deposit detection). It has a function to electrically cut off the power supply voltage applied to the motor when the delay time of the above has elapsed. More specifically, in this "electronic circuit", a predetermined delay time elapses from the time when the switch operating rod of the motor having blades first abuts on the actuator part of the microswitch which is the switch part. It also has a function to electrically cut off the power supply voltage applied to the motor. Here, the "predetermined delay time" is, for example, when the micro switch is used as a switch unit, the rotation speed of the motor and the movable contact in the micro switch move from one fixed contact to the other fixed contact facing each other. It is set based on the distance to.

<Level switch configuration>
FIG. 3 is a block diagram schematically showing the electrical configuration of the paddle type (rotary type) level switch 100 according to the present embodiment. For convenience of understanding, FIG. 3B schematically shows a side view of the motor. In FIG. 3, a configuration of a motor 4 having a flat plate-shaped blade 5 rotating in the R direction, a configuration of a microswitch 6, and a switch which is an accessory component of the motor 4 when a measurement object (not shown) is detected. The operation of the operating rod 4B moving in the D direction to contact and press the actuator portion 6A of the microswitch 6 is the same as the corresponding

components

5, 4, 6, 4A, 4B, 6A shown in FIG. Yes, the above-mentioned description regarding FIG. 1 is incorporated.

The power supply 1 of the level switch 100 is composed of a commercial power supply 2 and a voltage generation circuit 3 connected to the commercial power supply 2. Here, the voltage generation circuit 3 is an electronic circuit compatible with a commercial power supply 2 that supplies an AC voltage in the range of AC90V to AC264V. That is, the voltage generation circuit 3 1) AC / DC-converts the supply voltage of the commercial power supply 2 and then generates, for example, a DC voltage of DC5V (second level DC power supply voltage), and the DC voltage of the DC5V will be described later. The first signal S1 that supplies the

components

6, 7, and 9 and 2) generates an AC voltage of AC24V (first level AC power supply voltage) from the supply voltage of the commercial power supply 2 and then gives the AC voltage. Is supplied to each of the

components

10 and 4, which will be described later. The DC voltage value DC5V and the AC voltage value AC24V are examples, and the DC voltage value and the AC voltage value are set to arbitrary values, respectively.

On the other hand, the microswitch 6 is provided with an input terminal (input terminal) to which the DC voltage of DC5V is applied from the voltage generation circuit 3, and the input terminal is one of the above-mentioned fixed contacts T2 (inside the microswitch 6). See FIG. 2). On the other hand, the microswitch 6 has an output terminal (output terminal) connected to a fixed terminal T1 (see FIG. 2) inside the microswitch 6, and outputs a second signal S2 from the output terminal.

The delay circuit 7 forming the core of the level switch 100 is composed of an electronic circuit (IC), and is connected to the output terminal of the microswitch 6 to receive the second signal S2, and the second signal. Output terminal (output terminal) that outputs a third signal (control signal) S3 having a level corresponding to the level of the second signal S2 when a predetermined delay time α has elapsed from the time of receiving S2. have. Here, the predetermined delay time α is, as described above, the rotational speed of the motor 4 and the movable contact T4 (see FIG. 2) in the microswitch 6 from one fixed contact T2 to the other fixed contact T3 facing each other. It is the time calculated based on the distance to lateral movement. The calculated time is set in advance in the delay circuit 7 as a predetermined delay time α. For example, the predetermined delay time α is set to 0.05 seconds to 0.1 seconds.

The motor driver 8 includes a control circuit 9 which is an electronic circuit (IC) for controlling the switching operation of the semiconductor element (switch) 10 and a semiconductor element 10 which functions as a switching element. Of these, the control circuit 9 has an input terminal (input terminal) for receiving the third signal S3 output by the delay circuit 7 and an output terminal (output terminal) for outputting the fourth signal S4 as a control signal to the semiconductor element 10. ) Is provided. On the other hand, the semiconductor element (switch) 10 is composed of, for example, a triac which is a bidirectional switching element. The semiconductor element 10 is an input terminal (input terminal) connected to the voltage generation circuit 3 to receive the first signal S1 of AC24V, and a control terminal (control terminal; base) connected to the control circuit 9 to receive the fourth signal S4. It has an electrode (or a gate electrode) and an output terminal (output terminal) that is connected to the input terminal of the motor 4 and transmits the first signal S1 of AC24V to the motor 4.

<Operation / advantage of level switch>
A When the object to be measured is not detected In this case, the shaft 4A and the blade 5 of the motor 4 are rotating in the R direction, and the movable contact T4 in the microswitch 6 is in mechanical contact with one fixed contact T2. It is in. Therefore, the microswitch 6 outputs a second signal S2 that gives a level of DC5V to the delay circuit 7. Then, the delay circuit 7 outputs the third signal S3, which is at a level of maintaining the semiconductor element 10 in the ON state, to the motor driver 8. Therefore, the semiconductor element 10 functions as a switch in the ON state, and outputs the first signal S1 that gives the level of AC24V applied to the semiconductor element 10 to the input terminal of the motor 4, and the shaft 4A of the motor 4 And the blade 5 continues to rotate in the R direction.

B When detecting the object to be measured In this case, the blade 5 of the motor 4 comes into contact with the object (deposit), so that the rotation of the blade 5 and the shaft 4A in the R direction is stopped or suppressed. For this purpose, the switch operating rod 4B of the motor 4 instantly moves in the D direction and comes into contact with the actuator portion 6A of the microswitch 6 to apply the pressing F to the actuator portion 6A. In response to this pressing F, the conductive tension spring 6B inside the microswitch 6 is instantly deformed, and the movable contact T4 is instantly mechanically separated from one fixed contact T2. Depending on the timing of the contact, the microswitch 6 momentarily indicates a second signal S2 (specifically, a non-conducting state in which the voltage of DC5V applied to the input terminal is not applied to the output terminal. Specifically, the current I = 0A) (OFF level output signal) flowing through the microswitch 6 is output to the input terminal of the delay circuit 7. The delay circuit 7 having a counter function instantly responds to the reception timing of the second signal S2 at such a level, and starts an operation of counting the elapse of the delay time α from the time of the reception. Then, when the delay time α elapses, the delay circuit 7 instantly changes the state of the semiconductor element 10 from the ON state to the OFF state (specifically, voltage = 0V) (switching level). ) Is applied to the control terminal of the motor driver 8. As a result, the semiconductor element 10 instantly switches from the ON state to the OFF state in response to the fourth signal S4, which is the control signal of the control circuit 9, and is between the voltage generation circuit 3 and the input terminal of the motor 4. The circuit of is made non-conducting, and the supply voltage of AC24V applied to the motor 4 is cut off. As a result, the motor 4 is surely and completely turned off. In this way, the delay circuit 7 shifts to a state of counting the time when the delay time α elapses from the time of receiving the second signal S2 output from the output terminal of the microswitch 6 at the time of detecting the object to be measured. ing. By providing such a delay time α, the microswitch 6 can be switched to the completely OFF state without stopping in the unstable region USR of FIG. As a result, the continuous generation of chattering or arc is suppressed, so that the wear of each contact in the microswitch 6 due to the continuation of chattering or the like can be reliably suppressed. Therefore, the electronic circuit including the delay circuit 7 and the motor driver 8 that functions as a switch for the power supply of the motor 4 does not form a suicide circuit, and the voltage that is reliably and completely applied to the motor 4 after the delay time α elapses. Will be blocked. If the output terminal of the microswitch 6 is directly connected to the control terminal of the motor driver 8 without providing the delay circuit 7, the semiconductor element 10 repeats the ON / OFF state according to the chattering of the microswitch 6. It operates and causes the same trouble as the suicide circuit. In that sense, it can be said that the fact that the electronic circuit of the level switch 100 forms the delay circuit 7 is indispensable as a means for overcoming the above-mentioned problems.

From the above description, the level switch 100 according to the present embodiment has the following advantages or effects.

The level switch 100 does not constitute a conventional suicide circuit because it forms a switching and delay circuit for the power supply of the motor 4 by an electronic circuit. Therefore, the level switch 100 does not cause a problem associated with the suicide circuit described above, and always ensures that the power supply to the motor is supplied when the object to be measured is detected, regardless of the configuration and lot of the microswitch used. And it can be cut completely. Then, it is possible to surely suppress the occurrence of wear of each contact in the micro switch 6.

B. In the conventional level switch, it is necessary to specify the supply voltage to the motor, such as AC100V, AC200V, or AC240V. In that respect, since the level switch 100 generates the supply voltage by using the voltage generation circuit 3 composed of an electronic circuit, the supply voltage range is set to be wide, and the voltage range of AC90V to AC264V is practically used. You can use a commercial power supply at.

(Modification example)
(1) In the first embodiment, the motor driver 8 is connected between the voltage generating circuit 3 and the input terminal of the motor 4, but instead of this, the motor driver is connected between the output terminal of the motor 4 and the voltage generating circuit 3. 8 may be connected or arranged. The power supply voltage for the motor functions as a switching circuit unit in the sense that not only the arrangement of the motor driver 8 in the first embodiment but also the arrangement of the motor driver 8 in the modification (1) is included. It is applied to the motor 4 via the motor driver 8.

(2) In the first embodiment, the micro switch 6 is adopted as the "switch portion" on the motor 4 side, but as the "switch portion" on the motor 4 side instead of the micro switch 6, for example, a relay or a photocoupler. Other switching components may be used. Even in such a modification (2), the same action / advantage as that of the first embodiment described above can be obtained.

(3) In the first embodiment, the semiconductor element 10 is adopted as the switching element in the motor driver 8, but instead of the semiconductor element 10, another switching component such as a relay or a photocoupler is adopted. You may. Even in this case, the motor driver according to the present modification performs the same operation and function as the motor driver 8 according to the first embodiment, and as a result, the same advantages as those of the first embodiment are obtained in the present modification. You can get it even if you do.

(Additional note)
Although the embodiments of the present invention have been disclosed and described in detail above, the above description exemplifies applicable aspects of the present invention, and the present invention is not limited thereto. That is, it is possible to consider various modifications and / or modifications to the described aspects within a range that does not deviate from the scope of the present invention.

The present invention is suitable for application to, for example, a paddle type (rotary type) level switch that detects the presence or absence of a measured object such as powder or granules.

100 Level switch 100A Suicide circuit 1 Power supply 2 Commercial power supply 3 Voltage generation circuit 4 Motor 4A Shaft (main shaft)
4B switch operating rod 5 blades 6 micro switch (switch part)
6A Actuator 7 Delay circuit 8 Motor driver α Delay time 9 Control circuit (IC)
10 Semiconductor element (switch)

Claims

The power supply applied to the motor at a time when a predetermined delay time has elapsed from the first time when the motor shifts from the ON state to the OFF state due to the rotation of the motor around the shaft when the blades are restrained. Equipped with an electronic circuit that electrically cuts off the voltage
The electronic circuit is located in the electrical system of the electronic circuit.
It is equipped with only one switch unit that detects the first time point when the motor shifts from the ON state to the OFF state.
The electronic circuit is electrically delayed by the predetermined delay time from the first time point in response to the detection signal of the first time point output by only one switch unit in the electric system. A level switch, characterized in that at a point in time, the power supply voltage of the motor is electrically cut off.
An electron that electrically cuts off the power supply voltage applied to the motor when a predetermined delay time has elapsed from the time when the switch operating rod of the motor having blades first abuts on the actuator portion of the micro switch. Equipped with a circuit
The electronic circuit is located in the electrical system of the electronic circuit.
It comprises only one microswitch that detects the first contact point of the switch actuating rod with the actuator section.
The electronic circuit is electrically delayed by the predetermined delay time from the contact point in response to the detection signal at the contact point output by only one microswitch in the electrical system. A level switch, characterized in that at a point in time, the power supply voltage of the motor is electrically cut off.
The level switch according to claim 2.
The predetermined delay time is set based on the rotation speed of the motor and the distance from the movable contact in the one microswitch to the movement from one fixed contact to the other fixed contact facing the other. ,Level switch.
A motor having blades arranged at one end of the shaft and a switch operating rod attached to the other end of the shaft.
It is a level switch equipped with an electronic circuit.
The electronic circuit is located in the electrical system of the electronic circuit.
Only one switch part and
A delay circuit having an input end connected to the output end of only one switch unit,
It is equipped with a motor driver having an input end connected to the output end of the delay circuit.
A power supply voltage for the motor is applied to the motor via the motor driver.
At the first time when the switch operating rod shifts the switch portion of only one from the ON state to the OFF state due to the rotation of the motor around the shaft when the rotating blades are restrained, the switch operating rod is said to be in the OFF state. The only switch unit, which was in the ON state before the first time point, outputs an output signal indicating that it is in the OFF state to the input terminal of the delay circuit.
The delay circuit switches the motor driver in the ON state to the OFF state at a time when the motor driver in the ON state is electrically delayed by a predetermined delay time from the time when the output signal is received from only one switch unit. The control signal to be operated is output to the input terminal of the motor driver, and the control signal is output.
The motor driver is a level switch characterized by switching from the ON state to the OFF state in response to reception of the control signal to shut off the power supply voltage for the motor.