JP6068058B2 - Magnetic contactor - Google Patents

Description

  The present invention relates to an electrical circuit switch, and more particularly to an electromagnetic contactor that controls opening and closing of a pair of contacts using an electromagnet.

  Patent Document 1 discloses a sealed contact device suitable for an electromagnetic switch. The sealed contact device disclosed in Patent Document 1 has a contact mechanism in a sealed container. The contact mechanism has a pair of contacts arranged opposite to each other. The sealed contact device can turn on and off a high current by controlling the contact and separation of the pair of contacts.

JP-A-9-259728

However, since the sealing container is opaque, the contact mechanism disposed in the sealing container cannot be visually recognized from the outside unless the sealing container is removed from the sealing contact device. Since it is extremely difficult to remove the sealing container during the operation of the sealed contact device, it is difficult to visually confirm the conductive / non-conductive state of the contact mechanism during the operation of the sealed contact device. For this reason, if the current does not flow through the electrical circuit connected to the sealed contact device even though the sealed contact device is controlled to be in a conductive state, the contact mechanism is not operating or the contact mechanism is There is a problem that the state of the contact mechanism, such as whether the pair of contacts that are operating is not sufficiently in contact, cannot be confirmed.
Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide an electromagnetic contactor capable of detecting contact continuity even when the contact cannot be visually observed. There is to do.

An electromagnetic contactor according to an aspect of the present invention includes a pair of contacts that are arranged so as to be capable of contacting and separating, a coil of an electromagnet that controls contact and separation of the pair of contacts, and the coil connected in series to the coil. It has a switching element for controlling a current to be supplied, and a voltage detection circuit for detecting a voltage between terminals of the switching element.
Moreover, the electromagnetic contactor by 1 aspect of this invention can have a display part which displays the operation state of a pair of said contact based on the said voltage between terminals.
The voltage detection circuit may detect an inflection point generated in the inter-terminal voltage generated based on the contact of the pair of contacts.
In addition, the voltage detection circuit can detect whether or not the inflection point is generated within a predetermined period after the pair of contacts starts transition from the separated state to the contact state.

  The voltage detection circuit includes a surge voltage removal circuit that removes a surge voltage superimposed on the inter-terminal voltage, and a high-frequency noise removal circuit that removes a high-frequency noise signal superimposed on the output voltage output by the surge voltage removal circuit; An amplification circuit that amplifies the voltage level of the output voltage output from the high-frequency noise removal circuit, a differentiation circuit that differentiates the output voltage output from the amplification circuit, an output voltage output from the differentiation circuit, and a predetermined threshold voltage And a comparison circuit for comparing.

The electromagnetic contactor according to an aspect of the present invention may further include an opaque housing case that houses the pair of contacts.
Further, the pair of one contact, inserted in a current path, wherein a fixedly arranged pair of fixed contacts with a predetermined interval in the yield capacity case, the other of the pair of contacts, said pair It may be a movable contact arranged so as to be able to contact and separate from the fixed contact.

  According to the present invention, contact continuity can be detected even when the contact cannot be visually observed.

It is sectional drawing of schematic structure of the electromagnetic contactor 1 by one embodiment of this invention. It is a figure which shows the circuit structure of the electromagnetic contactor 1 by one embodiment of this invention. It is an actual measurement waveform of source-drain voltage Vds of the switching element 16 provided in the electromagnetic contactor 1 by one Embodiment of this invention. It is a circuit block diagram of the voltage detection circuit 17 with which the electromagnetic contactor 1 by one embodiment of this invention was equipped. It is a figure which shows an example of the circuit structure of the voltage detection circuit 17 with which the electromagnetic contactor 1 by one embodiment of this invention was equipped. It is a figure which shows the simulation operation | movement waveform of the voltage detection circuit 17 with which the electromagnetic contactor 1 by one embodiment of this invention was equipped.

  An electromagnetic contactor according to an embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the electromagnetic contactor 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view of an electromagnetic contactor 1 according to this embodiment. The electromagnetic contactor 1 according to the present embodiment can be applied to both direct current and alternating current. As shown in FIG. 1, the magnetic contactor 1 has an exterior case (storage case) 20. The outer case 20 is made of, for example, an opaque synthetic resin. For this reason, a pair of contacts 33 (details will be described later) disposed in the exterior case 20 are not visible from the outside. The exterior case 20 includes a bottomed cylindrical body 20a whose lower end surface is opened and a bottom plate 20b that closes the lower end surface of the bottomed cylindrical body 20a.

  In the exterior case 20, a contact device 2 having a contact mechanism and an electromagnet unit 3 as an electromagnet device for driving the contact device 2 are accommodated. The electromagnet unit 3 is disposed on the bottom plate 20 b, and the contact device 2 is disposed on the electromagnet unit 3. The contact device 2 and the electromagnet unit 3 are housed in series in the outer case 20. The contact device 2 has a contact storage case 4. The contact storage case 4 is formed of ceramics, synthetic resin, or the like, and has a bowl-like body 4a whose lower end is opened, a metal joint member 4b that is closely fixed to an open end surface of the bowl-like body 4a, and a bowl-like body 4a. It is comprised with the metal cylinder 4c which covers a side surface. The joining member 4b is fixed in an airtight state to the upper surface of the upper magnetic yoke 22 of the electromagnet unit 3 by brazing or welding.

  On the upper surface of the bowl-shaped body 4a, through holes 24a and 24b having a circular cross section are provided with a predetermined interval in the longitudinal direction. A pair of, for example, copper fixed contacts 6a and 6b are inserted into the through holes 24a and 24b. The pair of fixed contacts 6a and 6b are fixed to the through holes 24a and 24b with an adhesive or the like. Each of the fixed contacts 6a and 6b includes an upper-side large-diameter head 7 and a lower-side small-diameter cylindrical portion 8 that is coaxially connected to the large-diameter head 7.

The fixed contacts 6a and 6b are fixed to the flange 4a with an adhesive or the like with the small-diameter cylindrical portion 8 inserted through the through holes 24a and 24b. The fixed contacts 6 a and 6 b are configured to seal the through holes 24 a and 24 b with the small diameter cylindrical portion 8. Further, the contact device 2 has a movable contact 11 that is disposed to face the lower end surface of the small diameter cylindrical portion 8 of the fixed contacts 6a and 6b with a relatively narrow predetermined gap. The movable contact 11 is disposed so as to face and separate from the lower end surface of the small-diameter cylindrical portion 8. The movable contact 11 is attached to the contact holder 13 by being biased upward by a contact spring 14. The contact holder 13 is connected to a movable plunger 25 of the electromagnet unit 3 described later and is driven in the vertical direction. The fixed contacts 6a and 6b and the movable contact 11 constitute a pair of contacts 33 that can be brought into contact with and separated from each other, that is, can take either a contact state or a separated state. For example, one of the pair of contacts 33 is the fixed contacts 6 a and 6 b and the other is the movable contact 11.
External connection terminal plates 15a and 15b are screwed to the large-diameter heads 7 of the fixed contacts 6a and 6b.

The electromagnet unit 3 has a U-shaped magnetic yoke 21 as viewed from the side. A cylindrical portion 21 b having an open lower end is formed at the center of the bottom plate portion 21 a of the magnetic yoke 21. The upper surface side of the magnetic yoke 21 is connected by the upper magnetic yoke 22.
A coil holder 32 around which an exciting coil (electromagnet coil) 23 is wound is mounted on the outer peripheral surface of the cylindrical portion 21 b of the magnetic yoke 21. A cylindrical cap 26 with a bottom having a movable plunger 25 slidably mounted therein is disposed on the inner peripheral surface of the cylindrical portion 21b. A rubber seat 27 that contacts the bottom surface of the movable plunger 25 and absorbs an impact when the movable plunger 25 descends is disposed on the bottom surface of the cap 26.

  A connecting shaft 28 is fitted in the center of the movable plunger 25. The head of the connecting shaft 28 extends upward through a through hole 29 formed in the upper magnetic yoke 22 and is connected to the contact holder 13. A spring insertion hole 30 is formed around the connecting shaft 28 of the movable plunger 25. A return spring 31 that biases the movable plunger 25 downward is mounted between the spring insertion hole 30 and the upper magnetic yoke 22.

Hydrogen gas, nitrogen gas, a mixed gas of hydrogen and nitrogen in a sealed space constituted by the contact housing case 4 constituted by the bowl-shaped body 4a, the joining member 4b and the metal cylinder 4c, the upper magnetic yoke 22 and the cap 26, An arc extinguishing gas such as air or SF6 is enclosed.
The magnetic contactor 1 has a control circuit board 9 disposed on, for example, the external connection terminal plates 15a and 15b. The control circuit board 9 has an electromagnet coil control circuit 34 (not shown in FIG. 1) for controlling the electromagnet unit 3. The control circuit board 9 is housed in a board case 35 provided on the external connection terminal plates 15a and 15b.

  Next, the circuit configuration of the magnetic contactor 1 will be described with reference to FIGS. FIG. 2 shows a main part of the circuit configuration of the magnetic contactor 1 together with the main circuit board 9 connected to the electromagnetic contactor 1. As shown in FIG. 2, the control circuit board 9 provided in the electromagnetic contactor 1 has an electromagnet coil control circuit 34 and a voltage detection circuit 17. The electromagnet coil control circuit 34 includes a switching element 16 that controls the current supplied to the exciting coil 23 provided in the electromagnet unit 3 and a switching element drive circuit 18 that controls on / off of the switching element 16. . The switching element drive circuit 18 has a pulse width modulation (PWM) circuit (not shown). The switching element driving circuit 18 adjusts the ON state time and the OFF state time of the switching element 16 by PWM driving in order to flow a predetermined amount of current through the exciting coil 3.

  The switching element 16 is composed of, for example, an N-channel field effect transistor (FET). The drain terminal D of the switching element 16 is connected to one terminal of the exciting coil 23, and the source terminal S is connected (grounded) to the ground. The gate terminal G of the switching element 16 is connected to a signal output terminal (not shown) of the switching element drive circuit 18 that outputs a PWM drive signal. The other terminal of the exciting coil 23 is connected to the power supply circuit 10 provided in the electromagnetic contactor 1. The exciting coil 23 and the switching element 16 are connected in series between the power supply circuit 10 and the ground.

The voltage detection circuit 17 has input terminals 17a and 17b. A drain terminal D is connected to the input terminal 17a, and a source terminal S is connected to the input terminal 17b. The voltage detection circuit 17 detects the inter-terminal voltage of the switching element 16, that is, the source-drain voltage Vds between the source terminal S and the drain terminal D. As will be described in detail later, the voltage detection circuit 17 particularly detects whether or not an inflection point has occurred in the source-drain voltage Vds.
The power supply circuit 10 is a supply source of a voltage applied to the exciting coil 23 and a supplied current. The power supply circuit 10 includes, for example, a DC-DC converter circuit (not shown), and generates a voltage and a current necessary for the exciting coil 23 to generate a desired magnetic field from the power supply voltage VDD of the main circuit 5. ing.

  The main circuit 5 supplies a load 5c whose opening and closing is controlled by the electromagnetic contactor 1, a pair of contacts 33, external connection terminal plates 15a and 15b, and a voltage applied to the load 5c and a supplied current. And a power supply circuit 5d serving as a source. The external connection terminal plate 15a is connected to the output terminal 5a of the power supply circuit 5d, and the external connection terminal plate 15b is connected to the input terminal 5b of the load 5c. The power supply circuit 5d includes, for example, a DC-DC converter circuit (not shown), and generates a voltage and current necessary for the load 5c from the same power supply voltage VDD applied to the power supply circuit 10. When the pair of contacts 33 is in a contact state (closed state), the input terminal 5b of the load 5c is connected to the output terminal 5a of the power supply circuit 5d via the external connection terminal plate 15b, the pair of contacts 33 and the external connection terminal plate 15a. Is done. Thereby, the electromagnetic contactor 1 will be in the electric power supply state which applies a voltage to the load 5c, or supplies an electric current. On the other hand, when the pair of contacts 33 are separated (opened), the load 5 c is disconnected from the power supply circuit 5 d by the pair of contacts 33. Thereby, the magnetic contactor 1 will be in the electric power supply stop state which does not apply a voltage or supply an electric current to the load 5c.

  Next, the source-drain voltage Vds detected by the voltage detection circuit 17 will be described with reference to FIG. 3 and FIG. FIG. 3 shows the measured waveform of the source-drain voltage Vds when the switching element 16 is switched from the off state to the on state, from the middle of the voltage rise. In the upper part of the figure, the voltage waveform of the terminal voltage V5b between the input terminal 5b of the load 5c and the ground is shown, and in the lower part of the figure, the voltage waveform of the source-drain voltage Vds is shown. In the figure, the vertical axis represents voltage, the horizontal axis represents time, and the time has elapsed from left to right in the figure. The voltage scale of the vertical axis in the terminal voltage V5b is 1 V / div, the voltage scale of the voltage waveform of the vertical axis in the source-drain voltage Vds is 0.1 V / div, and the time scale of the horizontal axis in both voltage waveforms is 10 msec / div.

  When the switching element 16 is turned on, the source-drain voltage Vds rises as shown in FIG. As a result, when the current starts to flow through the exciting coil 23 and the current value of the current flowing through the exciting coil 23 reaches a predetermined value (time t in the figure), the pair of contacts 33 shifts from the separated state to the contact state, The voltage value of the terminal voltage V5b is changed from 0V to 2.5V, for example. When the pair of contacts 33 shifts from the separated state to the contact state, the output terminal 5a of the power supply circuit 5d and the input terminal 5b of the load 5c, which are in the open state, are short-circuited by the pair of contacts 33. For this reason, the impedance between the pair of connection terminals 5a and 5b changes from a relatively high value (for example, a value that can be regarded as infinity) to a lower value (for example, a value that can be regarded as 0Ω). . Due to this change in impedance, the voltage value of the output terminal 5a instantaneously decreases. This instantaneous voltage drop sequentially affects the power supply voltage VDD, the output voltage of the power supply circuit 10 and the source-drain voltage Vds, and the voltage values of the power supply voltage VDD, the output voltage, and the source-drain voltage Vds are instantaneous. To drop. As a result, as shown in FIG. 2 surrounded by a virtual circle α, an inflection point is generated in the source-drain voltage Vds based on this instantaneous voltage drop. Since this inflection point is generated when the pair of contacts 33 are in contact, the voltage detection circuit 17 determines whether or not this inflection point occurs after the pair of contacts 33 starts shifting from the separated state to the contact state. By detecting, it is possible to determine whether the pair of contacts 33 are in contact with or separated from each other, that is, whether the fixed contacts 6a and 6b and the movable contact 11 are in contact with each other.

  Next, the circuit configuration of the voltage detection circuit 17 will be described with reference to FIGS. FIG. 4 is a block diagram of the circuit configuration of the voltage detection circuit 17. The voltage detection circuit 17 includes a surge voltage removal circuit 41, a high frequency noise removal circuit 43, an amplification circuit 45, a differentiation circuit 47, and a comparison circuit 49. The high-frequency noise removal circuit 41 removes a surge voltage superimposed on the input source-drain voltage Vds of the switching element 16 and prevents a high voltage from being applied to the voltage detection circuit 17. The high frequency noise removal circuit 43 removes the high frequency noise signal superimposed on the output voltage output from the surge voltage removal circuit 41 to prevent the high frequency noise signal from being detected as an inflection point. The amplifying circuit 45 amplifies the voltage level of the output voltage output from the high frequency noise removing circuit 43. As shown in FIG. 3, since the voltage change at the inflection point is about 50 mV and the voltage fluctuation amount is small, the voltage detection circuit 17 may fail to detect the generated inflection point. For this reason, the voltage detection circuit 17 can amplify the detection error of the inflection point by amplifying the output voltage from the high frequency noise removal circuit 43 by about 20 times by the amplification circuit 45. The differentiating circuit 47 differentiates the output voltage output from the amplifying circuit 45 and extracts the inflection point. The comparison circuit 49 compares the output voltage output from the differentiating circuit 47 with a predetermined threshold voltage, and when the output voltage falls below the predetermined threshold voltage, the voltage having a voltage value different from the voltage output until then. After that, when the output voltage exceeds a predetermined threshold voltage, the voltage value of the output voltage is restored.

  Next, a specific circuit configuration of the voltage detection circuit 17 will be described with reference to FIG. FIG. 5 is an example of a specific circuit configuration of the voltage detection circuit 17 and is a circuit diagram used for an operation simulation of the voltage detection circuit 17. As shown in FIG. 5, the surge voltage removal circuit 41 provided in the voltage detection circuit 17 has a Zener diode 41a. The cathode of the Zener diode 41a is connected to the input terminal 17a. The anode of the Zener diode 41a is connected (grounded) to the input terminal 17b and the ground. The cathode is connected to the drain terminal D (not shown) of the switching element 16 via the input terminal 17a, and the anode is connected to the source terminal S (not shown) of the switching element 16 via the input terminal 17b. . When an applied voltage equal to or higher than the Zener voltage of the Zener diode 41a is applied to the input terminals 17a and 17b, the surge voltage removal circuit 41 reduces the voltage value of the applied voltage to the forward voltage of the Zener diode 41a. Thus, the surge voltage removal circuit 41 prevents a high voltage from being applied to the circuits 43 to 49 provided in the voltage detection circuit 17 other than the surge voltage removal circuit 41.

  The high frequency noise removing circuit 43 has a low-pass filter composed of a resistor 43a and a capacitor 43b. One terminal of the resistor 43a is connected to the input terminal 17a and the cathode of the Zener diode 41a, and the other terminal is connected to one electrode of the capacitor 43b. The other electrode of the capacitor 43b is connected (grounded) to the input terminal 17b, the anode of the Zener diode 41a, and the ground. The resistance value of the resistor 43a and the capacitance value of the capacitor 43b are set so that the cutoff frequency of the low-pass filter is higher than the reciprocal of the period of the inflection point generated in the source-drain voltage Vds. Thereby, the high frequency noise removal circuit 43 can output the voltage from which only the high frequency noise is removed while leaving the inflection point generated in the source-drain voltage Vds. In the present embodiment, the high-frequency noise removal circuit 43 has a passive low-pass filter, but may of course have an active low-pass filter using an operational amplifier or the like.

  The amplifier circuit 45 includes an operational amplifier 45a and resistors 45b and 45c connected in series between the output terminal OUT of the operational amplifier 45a and the ground. One terminal of the resistor 45b is connected to the output terminal OUT of the operational amplifier 45a, and the other terminal is connected to one terminal of the resistor 45c. The other terminal of the resistor 45c is connected (grounded) to the ground. The non-inverting input terminal (+) of the operational amplifier 45a is connected to the other terminal of the resistor 43a of the high frequency noise removing circuit 43 and one electrode of the capacitor 43b. The inverting input terminal (−) of the operational amplifier 45a is connected to the other terminal of the resistor 45b and one terminal of the resistor 45c. The resistance values of the resistors 45b and 45c are set so that the operational amplifier 45a has an amplification factor of about 20. The amplifier circuit 45 functions as a non-inverting amplifier circuit, and amplifies and outputs the output voltage output from the high-frequency noise removing circuit 43 without inverting the phase.

  The differentiation circuit 47 has a high-pass filter composed of a capacitor 47a and a resistor 47b. One electrode of the capacitor 47a is connected to the output terminal OUT of the operational amplifier 45a of the amplifier circuit 45 and one terminal of the resistor 45b, and the other electrode is connected to one terminal of the resistor 47b. The other terminal of the resistor 47b is connected to an inverting input terminal (−) of an operational amplifier 49a (details will be described later) of the comparison circuit 49 and a cathode of a Zener diode 48b (details will be described later) of the threshold voltage generation circuit 48. The capacitance value of the capacitor 47a and the resistance value of the resistor 47b are set so that the cutoff frequency of the high-pass filter is lower than the reciprocal of the period of the inflection point generated in the source-drain voltage Vds. Thereby, the differentiating circuit 47 can output without losing the change of the inflection point generated in the source-drain voltage Vds, that is, the potential fluctuation of the source / drain voltage Vds at the inflection point. In the present embodiment, the differentiating circuit 47 has a passive high-pass filter, but may of course have an active high-pass filter using an operational amplifier or the like.

  The voltage detection circuit 17 has a buffer amplifier 67 that functions as an output buffer of the differentiation circuit 47. The buffer amplifier 67 has an operational amplifier 67a. The non-inverting input terminal (+) of the operational amplifier 67a is connected to the other electrode of the capacitor 47a of the differentiation circuit 47 and one terminal of the resistor 47b. The inverting input terminal (−) of the operational amplifier 67a and the output terminal OUT are connected. The buffer amplifier 67 has a voltage follower circuit configuration, and does not amplify the input voltage input from the differentiating circuit 47 (amplification degree is 1).

  The comparison circuit 49 receives the output voltage of the buffer amplifier 67. That is, the output voltage of the differentiation circuit 47 is input to the comparison circuit 49 via the buffer amplifier 67. The comparison circuit 49 compares the voltage level of the output voltage of the buffer amplifier 67 with the voltage level of the threshold voltage generated by the threshold voltage generation circuit 48. The comparison circuit 49 has an operational amplifier 49a and resistors 49b and 49c. One terminal of the resistor 49b is connected to the inverting input terminal (−) and the output terminal OUT of the operational amplifier 67a of the buffer amplifier 67, and the other terminal is connected to the non-inverting input terminal (+) of the operational amplifier 49a and one terminal of the resistor 49c. Yes. The output terminal OUT of the operational amplifier 49a is connected to the other terminal of the resistor 49c. The comparison circuit 49 is a hysteresis comparator. In the comparison circuit 49, hysteresis is provided in the threshold value so that the voltage level of the threshold value differs between when the input voltage input to the non-inverting input terminal (+) of the operational amplifier 49a rises and when it falls. Thereby, the comparison circuit 49 prevents malfunction due to a noise signal superimposed on the input voltage. The width of the hysteresis, that is, the difference between the threshold value when the input voltage increases (the lower limit value of the threshold voltage) and the threshold value when the input voltage decreases (the upper limit value of the threshold voltage) is determined by the resistance values of the resistors 49b and 49c. It is set to be smaller than the voltage fluctuation of the differential waveform at the pole.

  The voltage detection circuit 17 includes a threshold voltage generation circuit 48 that generates a threshold voltage input to the inverting input terminal (−) of the operational amplifier 49 a provided in the comparison circuit 49. The threshold voltage generation circuit 48 includes a resistor 48a and a Zener diode 48b. One terminal of the resistor 48a is connected to a voltage output terminal of an analog power supply Va for analog (for example, 12V), and the other terminal is a cathode of a Zener diode 48b, the other terminal of the resistor 47b of the differentiating circuit 47b, and an inversion of the operational amplifier 49a. It is connected to the input terminal (-). The anode of the Zener diode 48b is connected (grounded) to the ground. The threshold voltage input to the comparison circuit 49 is a value obtained by dividing the voltage value of the analog power supply Va by the resistance value of the resistor 48a and the resistance value of the Zener diode 48b.

The other terminal of the resistor 47b of the differentiating circuit 47 is connected to a connection portion where the resistor 48a and the Zener diode 48b are connected. For this reason, the output voltage of the differentiating circuit 47 is entirely level-shifted to the threshold voltage level.
The positive power supply input terminals of the operational amplifier 45b of the amplifier circuit 45 and the operational amplifier 67a of the buffer amplifier 67 are connected to the voltage output terminal of the analog power supply Va, and the negative power supply input terminal is connected (grounded) to the ground. The positive power supply input terminal of the operational amplifier 49a of the comparison circuit 49 is connected to the voltage output terminal of the digital digital power supply Vd (for example, 5V), and the negative power supply input terminal is connected to the ground (grounded).

  Although not shown, the voltage detection circuit 17 includes, for example, a light emitting element driving circuit to which the output voltage of the comparison circuit 49 is input, and a light emitting element that is driven by the light emitting element driving circuit and whose light emission state can be visually recognized from the outside. ing. The light-emitting element driving circuit has a predetermined time after the switching element driving circuit 18 starts to input a gate signal to the gate terminal G of the switching element 16 when the pair of contacts 33 starts to shift from the separated state to the contact state. If the voltage level of the output voltage does not change, the light emitting element is turned on to notify the user of the electromagnetic contactor 1 that a problem has occurred in the pair of contacts 33. As described above, the voltage detection circuit 17 uses the output voltage of the comparison circuit 49 as a detection signal for detecting whether or not a failure occurs in the pair of contacts 33.

  A circuit 61 shown in FIG. 5 is a simulated voltage generation circuit that simulates the source-drain voltage Vds of the switching element 16, a circuit 63 is a withstand voltage test circuit for the voltage detection circuit 17, and a circuit 65 is an operational amplifier. 45b is a circuit for testing input protection, and both are circuits for simulating the operation of the voltage detection circuit 17, and thus detailed description thereof is omitted.

  Next, an operation simulation result of the voltage detection circuit 17 will be described with reference to FIG. FIG. 6 shows the simulation result of the voltage waveform of each part of the voltage detection circuit 17. In the uppermost part of the figure, the voltage waveform of the source-drain voltage Vds is shown, the second stage shows the voltage waveform of the output voltage V1 of the circuit 61 shown in FIG. 5, and the third stage shows the surge voltage. The voltage waveform of the output voltage V2 of the removal circuit 41 is shown, the voltage waveform of the output voltage V3 of the high frequency noise removal circuit 43 is shown in the fourth stage, and the same as the output voltage of the differentiation circuit 47 in the fifth stage. A waveform of the output voltage V4 of the buffer amplifier 67, which is a waveform, is shown, and a voltage waveform of the output voltage V5 of the comparison circuit 49 is shown in the final stage. In each voltage Vds, V1 to V5, the vertical axis represents voltage, and the horizontal axis represents time. The passage of time is shown from the left to the right in the figure. Note that the voltages V2, V3, V4, and V5 shown from the third stage to the last stage have a voltage rise start timing without changing the timing at which an inflection point is generated with respect to the source-drain voltage Vds shown in the uppermost stage. The voltage waveform falls at 1 ms later and at an elapsed time of 24 ms. The reason why the voltage waveforms of the voltages V2, V3, V4, and V5 are different from the source-drain voltage Vds is to prevent erroneous detection due to switching noise of the output voltage V1 in the simulation. The operation timings of these voltage waveforms are varied by the circuits 63 and 65 shown in FIG.

  As shown in the second stage of FIG. 6, at time t0 to t1, the high voltage (for example, constant 200V) output voltage V1 output from the circuit 61 is removed by the surge voltage removal circuit 41. Therefore, as shown in the third and subsequent stages in FIG. 6, the output voltage V2 of the surge voltage removing circuit 41 and the output voltage V3 of the high frequency noise removing circuit 43 are constant at about 0 V from time t0 to t1, and the buffer amplifier 67 Since the output voltage V4 is level-shifted, it is constant at about 3V. In the period from time t0 to t1, the voltage value of the output voltage V4 input to the non-inverting input terminal (+) of the operational amplifier 49a of the comparison circuit 49 is lower than the lower limit value of the threshold voltage input to the inverting input terminal (−). Therefore, the output voltage V5 of the comparison circuit 49 is at a high level (for example, constant at about 3V). In this example, the threshold voltage is the same voltage as the output voltage V4 in the period from time t0 to t1, and the lower limit value is, for example, several mV to several tens mV lower than the output voltage V4 in the period.

  In this simulation, after time t1, the circuit 61 is set to output the output voltage V1 having the same waveform as the source-drain voltage Vds shown in the upper part of the figure, so that the output voltage V2 of the surge voltage removal circuit 41 is set. Is the same waveform as the output voltage V1, the output voltage V3 of the high frequency noise removal circuit 43 is a voltage waveform obtained by removing high frequency noise from the output voltage V2, and the output voltage V4 of the buffer amplifier 67 is a differential waveform of the output voltage V3. . In the period from time t1 to time t2, the voltage value of the output voltage V4 input to the non-inverting input terminal (+) of the operational amplifier 49a of the comparison circuit 49 is higher than the upper limit value of the threshold voltage input to the inverting input terminal (−). Therefore, the output voltage V5 of the comparison circuit 49 is maintained at a high level. In this example, the upper limit value of the threshold voltage is, for example, several mV to several tens mV higher than the output voltage V4 in the period from time t0 to t1.

  An inflection point occurs in the output voltage V1 of the circuit 61 during the period from time t2 to t5. At the start point t2 of the inflection point, the voltage value of the output voltage V3 that has been increased starts to decrease. For this reason, the output voltage V4 that has started to converge to a constant voltage starts to decrease again from time t2, and at time t3, the voltage value of the output voltage V4 that is input to the non-inverting input terminal (+) of the operational amplifier 49a of the comparison circuit 49. Becomes lower than the upper limit value of the threshold voltage input to the inverting input terminal (−). As a result, at time t3, the output voltage V5 of the comparison circuit 49 shifts to a low level.

The lowered output voltage V3 starts to rise again. Therefore, the output voltage V4 also begins to rise, and at time t4, the threshold voltage at which the voltage value of the output voltage V4 input to the non-inverting input terminal (+) of the operational amplifier 49a of the comparison circuit 49 is input to the inverting input terminal (−). Higher than the lower limit of. As a result, at time t4, the output voltage V5 of the comparison circuit 49 shifts to a high level.
Thereafter, until the output voltage V1 of the circuit 61 becomes 0V, the voltage value of the output voltage V4 input to the non-inverting input terminal (+) of the operational amplifier 49a of the comparison circuit 49 is the threshold voltage input to the inverting input terminal (−). Therefore, the output voltage V5 of the comparison circuit 49 is maintained at a high level.

  Thus, the voltage detection circuit 17 can detect the inflection point generated in the source-drain voltage Vds of the switching element 16 when the pair of contacts 33 shifts from the separated state to the contact state. For this reason, the electromagnetic contactor 1 is within a predetermined period (in this example, from time t1 to 6 to 7.5 ms) from the time (in this example, time t1) when the pair of contacts 33 starts shifting from the separated state to the contact state. If the output voltage V5 does not become low level during a period of time), it can be determined that a failure has occurred in the pair of contacts 33.

  Next, the operation of the electromagnetic contactor 1 according to the present embodiment will be described with reference to FIGS. 1 to 6 again. It is assumed that the excitation coil 23 in the electromagnet unit 3 is in a non-energized state, and no excitation force for moving the movable plunger 25 by the electromagnet unit 3 is generated. In this state, the movable plunger 25 is urged downward by the return spring 31 away from the upper magnetic yoke 22 and comes into contact with the rubber seat 27. For this reason, the movable contact 11 supported by the contact holder 13 connected to the movable plunger 25 via the connection shaft 28 sandwiches a predetermined gap from the lower end surface of the small diameter cylindrical portion 8 of the fixed contacts 6a and 6b. The contact device 2 is in an open (released) state.

  When the switching device drive circuit 18 of the electromagnet coil control circuit 34 is driven and the switching device 16 is turned on in the open state of the contact device 2, a current flows from the power supply circuit 10, and the excitation coil 23 of the electromagnet unit 3 is energized. Is done. Thereby, the exciting force generated in the electromagnet unit 3 pushes the movable plunger 25 upward against the return spring 31. Accordingly, the contact holder 13 connected to the movable plunger 25 via the connecting shaft 28 moves upward, and the movable contact 11 contacts the bottom surface of the small-diameter cylindrical portion 8 of the fixed contacts 6a and 6b. 14 contact pressure, the pair of contacts 33 are in contact. As a result, the contact device 2 receives a load from the power supply circuit 5d through the output terminal 5a, the external connection terminal plate 15a, the fixed contact 6a, the movable contact 11, the fixed contact 6b, the external connection terminal plate 15b, and the input terminal 5b. A closed (turned on) state is supplied to 5c.

  When the current supply to the load 5c is interrupted from the closed state of the contact device 2, the switching element drive circuit 18 is set in a non-driven state, the switching element 16 is turned off, and voltage is applied to the excitation coil 23 of the electromagnet unit 3. And the current supply is stopped. As a result, the exciting force that moves the movable plunger 25 upward by the electromagnet unit 3 disappears, and the movable plunger 25 is lowered by the biasing force of the return spring 31. When the movable plunger 25 is lowered, the contact holder 13 connected via the connecting shaft 28 is lowered, and the movable contact 11 is fixed to the fixed contact while the contact spring 14 applies the contact pressure accordingly. 6a and 6b are in contact. After that, when the contact pressure of the contact spring 14 disappears, the movable contact 11 is lowered downward from the fixed contacts 6a and 6b, and the contact device 2 enters an open state in which the pair of contacts 33 are separated.

When the contact device 2 is in the open state, an arc is generated between the fixed contacts 6 a and 6 b and the movable contact 11. This arc is greatly extended by an arc extinguishing permanent magnet (not shown) and extinguished.
In this way, by controlling the exciting coil 23 of the electromagnet unit 3 to the non-energized state and the energized state, the contact device 2 moves away from the pair of fixed contacts 6a and 6b while the movable contact 11 maintains a predetermined gap. And the closed contact state in which the movable contact 11 is in contact with the pair of fixed contacts 6a and 6b.

  When the pair of contacts 33 are brought into contact, an inflection point occurs in the source-drain voltage Vds of the switching element 16 as shown in FIG. As described with reference to FIGS. 5 and 6, when the voltage detection circuit 17 detects the inflection point, for example, the light emitting element (not shown) is maintained in a non-lighted state, and the pair of contacts 33 operate normally. That the user of the magnetic contactor 1 is informed. On the other hand, if an abnormality occurs in the pair of contacts 33 and remains in a separated state, no inflection point occurs in the source-drain voltage Vds of the switching element 16. For this reason, the voltage detection circuit 17 cannot detect the inflection point within a predetermined time from the time when the pair of contacts 33 starts to shift from the separated state to the contact state. Inform the user of the magnetic contactor 1 that a problem has occurred in 33.

  As described above, the electromagnetic contactor 1 according to the present embodiment includes a pair of contacts 33 that are opposed to each other so as to be able to contact and separate, an excitation coil 23 that controls contact and separation of the pair of contacts 33, and the excitation coil 23. The switching element 16 is connected in series and controls the current supplied to the exciting coil 33, and the voltage detection circuit 17 detects the voltage between terminals of the switching element 16 (source-drain voltage Vds). Thereby, even when the exterior case 20 of the electromagnetic contactor 1 is opaque and the pair of contacts 33 cannot be visually recognized from the outside, or even when the exterior case 30 is transparent, the electromagnetic contactor 1 is attached to a predetermined location and is paired. Even when the contact 33 is not visible from the outside, the conduction of the pair of contacts 33 can be detected. Moreover, according to the electromagnetic contactor 1 by this Embodiment, it becomes unnecessary to visually confirm a pair of contact 33, and to measure the electric current which flows into the load 5c of the main circuit 5, for example.

The voltage detection circuit 17 provided in the electromagnetic contactor 1 detects an inflection point generated in the source-drain voltage Vds of the switching element 16 generated based on the contact of the pair of contacts 33. . According to the electromagnetic contactor 1 having the configuration, even when the pair of contacts 33 cannot be visually observed, the conduction of the pair of contacts 33 can be detected.
In addition, the voltage detection circuit 17 can detect whether or not an inflection point occurs within a predetermined period after the pair of contacts 33 starts shifting from the separated state to the contact state. According to the electromagnetic contactor 1 provided with the said structure, although the pair of contact 33 is driven so that it may be in a contact state, the fixed contacts 6a and 6b and the movable contact 11 are not in contact. Can be detected.

  The voltage detection circuit 17 also includes a surge voltage removal circuit 41 that removes a surge voltage superimposed on the source-drain voltage Vds, and a high-frequency noise removal that removes a high-frequency noise signal superimposed on the output voltage output from the surge voltage removal circuit 41. A circuit 43; an amplifying circuit 45 that amplifies the voltage level of the output voltage output from the high-frequency noise removing circuit 43; a differentiating circuit 47 that differentiates the output voltage output from the amplifying circuit 45; and an output voltage output from the differentiating circuit 47. And a comparison circuit 49 for comparing with a predetermined threshold voltage. According to the electromagnetic contactor 1 having this configuration, the surge voltage and noise signal are removed from the source-drain voltage Vds, and the voltage fluctuation of about several tens of mV at the inflection point generated in the source-drain voltage Vds is amplified. Can be detected.

The electromagnetic contactor 1 also has an opaque housing case (exterior case 20) that houses the pair of contacts 33. According to the electromagnetic contactor 1 having the configuration, even if the pair of contacts 33 is accommodated in the opaque outer case 20 and cannot be visually recognized, it is detected whether the pair of contacts 33 is conductive. Can do.
In addition, one of the pair of contacts 33 is a pair of fixed contacts 6a and 6b that are inserted in the current path and fixedly arranged in the exterior case 33 at a predetermined interval, and the other of the pair of contacts 33 is The movable contact 11 is disposed so as to be able to contact and separate from the pair of fixed contacts 6a and 6b. According to the electromagnetic contactor 1 provided with the said structure, even if the stationary contacts 6a and 6b and the movable contact 11 cannot be visually recognized from the outside, the stationary contacts 6a and 6b and the movable contact 11 are in contact with each other. It is possible to detect whether there is a separated state.

DESCRIPTION OF SYMBOLS 1 Electromagnetic contactor 2 Contact apparatus 3 Electromagnet unit 4 Contact storage case 4a Rod-like body 4b Joining member 4c Metal cylinder 5 Main circuit 5a Output terminal 5b Input terminal 5c Load 5d, 10 Power supply circuit 6a, 6b Fixed contact 9 Control circuit Substrate 11 Movable contact 13 Contact holder 14 Contact spring 15a, 15b External connection terminal plate 16 Switching element 17 Voltage detection circuit 17a, 17b Input terminal 18 Switching element drive circuit 20 Exterior case 20a Bottomed cylinder 20b Bottom plate 21 Magnetic yoke 22 Upper magnetic yoke 23 Excitation coil 24 Coil holder 25 Movable plunger 26 Cap 28 Connection shaft 31 Return spring 33 Pair of contacts 34 Electromagnetic coil control circuit 35 Substrate case 41 Surge voltage elimination circuits 41a and 48b Zener diode 43 High frequency noise elimination circuits 43a and 4 b, 45c48a, 49b, 49c resistors 43 b, 47a capacitor 45 amplifier circuit 45a, 49a, 67a operational amplifier 47 differential circuit 49 comparison circuit 67 buffer amplifier

Claims (7)

A pair of contacts arranged opposite to each other,
An electromagnet coil for controlling contact and separation of the pair of contacts;
A switching element connected in series to the coil and controlling a current supplied to the coil;
And a voltage detection circuit for detecting a voltage between terminals of the switching element. A display unit that displays an operation state of the pair of contacts based on the voltage between the terminals;
The electromagnetic contactor according to claim 1. The voltage detection circuit, an electromagnetic contactor according to claim 1 or 2, characterized in that detecting the inflection point generated in the inter-terminal voltage the pair of contacts is generated based on the contact. 4. The electromagnetic contact according to claim 3 , wherein the voltage detection circuit detects whether or not the inflection point is generated within a predetermined period after the pair of contacts starts transition from the separated state to the contact state. 5. vessel. The voltage detection circuit includes:
A surge voltage removing circuit for removing a surge voltage superimposed on the voltage between the terminals;
A high-frequency noise removal circuit for removing a high-frequency noise signal superimposed on the output voltage output by the surge voltage removal circuit;
An amplifying circuit for amplifying the voltage level of the output voltage output by the high-frequency noise removing circuit;
A differentiating circuit for differentiating the output voltage output from the amplifier circuit;
The electromagnetic contactor according to any one of claims 1 to 4 , further comprising: a comparison circuit that compares an output voltage output from the differentiation circuit with a predetermined threshold voltage. The electromagnetic contactor according to any one of claims 1 to 5, further comprising an opaque housing case that houses the pair of contacts. The one of the pair of contacts, are inserted in the current path, a fixedly arranged pair of fixed contacts with a predetermined interval in the yield capacity case,
The electromagnetic contactor according to claim 6 , wherein the other of the pair of contacts is a movable contact disposed so as to be able to contact with and separate from the pair of fixed contacts.

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