Contact running device

Abstract

To provide a contact running device capable of suppressing the increase in contact resistance of contacts by suppressing the gas phase arc.SOLUTION: The contact running device is configured to ensure that the voltage applied to a contact during contact running is 8 V or less, or the current value flowing through the contact is 0.3 A or less. With this, when the state where voltage is applied between the contacts changes to a state where both contacts are separated during contact running, even if air enters between the contacts, the arc can be suppressed from changing to a gas phase arc. Therefore, the increase in contact resistance of the contacts can be suppressed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a contact running device in a mechanical relay. [Background technology]

[0002] Conventionally, there have been mechanical relays that mechanically connect and disconnect a movable contact and a fixed contact to open and close an electric circuit (see, for example, Patent Document 1). With a mechanical relay, the mechanical relay is attached to a contact running device, and the contacts are repeatedly turned on and off a predetermined number of times to check operation and quality through contact running, that is, break-in operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-209056 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if a gas phase arc occurs during contact running by a contact running device, the surface of the metal that makes up the contact oxidizes, increasing the contact resistance of the contact and increasing the voltage drop between the contacts when the contacts are on.Increasing the contact force is one way to reduce the voltage drop between the contacts that increases due to contact running, but this requires increasing the coil attraction force to move the moving contact, which increases the size of the coil.

[0005] SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a contact running device that can suppress gas phase arcing and prevent an increase in contact resistance of the contacts. [Means for solving the problem]

[0006] In order to achieve the above object, the invention described in claim 1 is a contact running device that turns on and off the contact part of a mechanical relay (1) having a contact part composed of a movable contact (2) and a fixed contact (3) and an exciting coil (4) that generates a magnetic attraction force that controls the on / off of the contact part, and performs contact running by flowing a current through the contact part when the mechanical relay is turned on, a first power source (10) that applies a voltage to the contact portion; a second power source (20) that supplies current to the excitation coil; a drive switch (30) that controls the on / off of the current supply from the second power source to the excitation coil; a load (40) connected to the contact portion so that a current flowing through the contact portion is supplied when the contact portion is turned on; The voltage applied between the contacts in the contact section is set to 8V or less, or the current value of the current flowing through the contact section when the contact section is turned on is set to 0.3A or less.

[0007] In this way, the voltage applied to the contacts during running contacts is kept to 8V or less, or the current flowing through the contacts is kept to 0.3A or less. This prevents the arc from changing into a gas phase arc even if air gets between the contacts when the contacts separate while voltage is applied between them during running contacts. This makes it possible to suppress an increase in the contact resistance of the contacts.

[0008] At least, as set forth in claim 2, if the voltage applied between the contacts in the contact section is 8 V or less and the value of the current flowing through the contact section when the contact section is turned on is 20 A or less, it is possible to suppress the change to a gaseous phase arc. The same applies if the value of the current flowing through the contact section when the contact section is turned on is 0.3 A or less and the voltage applied between the contacts in the contact section is 14 V or less, as set forth in claim 3. Preferably, as set forth in claims 5 and 6, the surfaces of at least the movable contact and the fixed contact in the contact section are made of Ag or Cu, the voltage applied between the contacts in the contact section is 8 V or less, and the value of the current flowing through the contact section when the contact section is turned on is 0.3 A or less.

[0009] In the invention described in claim 8, a voltage limiting element (70) is provided which is connected in parallel to the load and limits the voltage applied to the contact portion to 8 V or less when the movable contact and the fixed contact are separated during contact running.

[0010] In this way, when a voltage limiting element is connected in parallel to the load, the voltage applied to the contacts can be limited to 8V or less when the contacts are separated during contact running. For example, if the voltage limiting element is configured with a capacitor, the capacitor will be charged when the contacts are closed during contact running. As a result, the voltage applied to the contacts will drop when the contacts are separated during contact running. This means that the voltage applied to the contacts can be limited, making it possible to suppress the transition to a gas phase arc.

[0011] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and the specific components described in the embodiments described below. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a diagram showing a circuit configuration of the contact running device according to the first embodiment. [Figure 2]1 is a cross-sectional explanatory view showing a mechanism for generating a gaseous phase arc and a mechanism for increasing the voltage drop between the contacts; FIG. [Figure 3] 1 is a diagram illustrating the mechanism by which a gas phase arc occurs and the mechanism by which the voltage drop between the contacts increases; FIG. [Figure 4] FIG. 10 is a diagram showing a circuit configuration of a contact running device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, identical or equivalent parts will be denoted by the same reference numerals.

[0014] (First embodiment) A first embodiment will be described. In this embodiment, a circuit configuration of a contact running device of a mechanical relay 1 will be described. Fig. 1 shows the circuit configuration when the mechanical relay 1 is attached to the contact running device of this embodiment, and the contact running device will be described in detail.

[0015] As shown in FIG. 1, the contact running device controls the on / off of a mechanical relay 1 to perform contact running, and is configured to include a first power source 10, a second power source 20, a coil drive switch 30, and a load 40.

[0016] Mechanical relay 1 has a contact section having movable contact 2 and fixed contact 3, as well as an excitation coil 4 that moves movable contact 2 when current is applied, and is configured by housing these in a case (not shown). Although the specific structure is not shown, terminals 5 and 6 that connect the contact section to a first power source 10 and the like, and terminals 7 and 8 that supply current to excitation coil 4 extend from the case. Each terminal is electrically connected to a predetermined location in a circuit that constitutes a contact running device, thereby enabling contact running.

[0017] The movable contact 2 is attached to the mover and is magnetically attracted when the excitation coil 4 is energized. The fixed contact 3 is fixed to the case and moves in contact with or separates from the movable contact 2 due to the magnetic attraction force generated by the excitation coil 4. The movable contact 2 and the fixed contact 3 are made of a metal that constitutes the contact material, such as Ag (silver) or Cu (copper). More specifically, the surfaces of the movable contact 2 and the fixed contact 3 may be oxidized due to arcing during energization, but they are made of Ag or Cu, at least when unused (in other words, when brand new). The contact material that constitutes the movable contact 2 and the fixed contact 3 is arbitrary; the entire contact may be made of the contact material, or only the surface may be made of the contact material and the rest may be made of another metal.

[0018] 1, the mechanical relay 1 is shown having one movable contact 2 and one fixed contact 3, but other structures are also possible. For example, the mechanical relay 1 may have one movable contact 2 at each end of a mover that is magnetically attracted when current is passed through the excitation coil 4, and fixed contacts 3 disposed at positions corresponding to each end of the mover, with each fixed contact 3 connected to a terminal extending from the case. An example of a mechanical relay 1 in which the movable contact 2 and fixed contacts 3 are made of Cu is a high-voltage sealed relay.

[0019] The first power source 10 supplies current to the load 40 through the contact portion when the contact portion is turned on, that is, when the movable contact 2 abuts against the fixed contact 3. In this embodiment, the voltage of the first power source 10 is set to 8 V or less.

[0020] The second power source 20 generates a magnetic attractive force by supplying a current to the excitation coil 4. This magnetic attractive force moves a mover equipped with a movable contact 2, and the movable contact 2 and the fixed contact 3 are brought into contact with or separated from each other. As shown in Fig. 1, when the mechanical relay 1 is of a normally open type, the excitation coil 4 generates a magnetic attractive force based on the current supplied from the second power source 20, and the movable contact 2 is moved toward the fixed contact 3, turning on the contact portion.

[0021] The coil drive switch 30 is turned on and off based on a coil drive signal input from a control device (not shown). For example, the coil drive switch 30 is configured with a semiconductor switching element such as an NPN transistor. When a coil drive signal with a predetermined on / off cycle is input to the base terminal of the coil drive switch 30, the coil drive switch 30 turns on the current path from the second power supply 20 to the excitation coil 4. When the coil drive switch 30 is configured with an NPN transistor, for example, the base-collector voltage V BC The voltage is set to 14±0.2 V, and a current is supplied to the exciting coil 4 so that a magnetic attraction force is generated that causes the movable contact 2 to abut against the fixed contact 3.

[0022] The number of times the coil drive switch 30 is turned on and off is the number of contact runnings, and this number can be set arbitrarily as long as it is the number of trials that allows the desired operation and quality checks to be performed through break-in. The on / off cycle of the coil drive switch 30 can also be set arbitrarily, but for example, an on / off cycle with an on time of 7.5 ms and an off time of 7.5 ms is used.

[0023] The load 40 is provided assuming a device in which switching is performed by the mechanical relay 1, and is, for example, a resistor load. In this embodiment, when the contact is running, the value of the current flowing through the contact portion is determined based on the resistance value of the load 40. For example, the resistance value of the load 40 is set to 0.7 Ω, and the value of the current flowing when the contact portion is turned on is set to 0.3 A or less.

[0024] The contact running device of this embodiment is equipped with an ammeter 50 for measuring the current flowing through the contacts and a voltmeter 60 for measuring the voltage between the contacts at the contacts, thereby making it possible to measure the value of the current flowing through the contacts and the amount of voltage drop between the contacts during contact running.

[0025] The contact running device is constructed as described above. The mechanism by which a gas phase arc occurs and the mechanism by which the voltage drop between the contacts increases will now be described with reference to Figures 2 and 3.

[0026] First, the coil drive switch 30 is turned on based on a coil drive signal, causing the movable contact 2 to abut against the fixed contact 3, and a state in which current is supplied from the first power source 10 to the load 40 through the contact portion. When the coil drive switch 30 is switched off from this state, as shown in step 1 of Figure 3, the contacts are separated while a voltage is applied between them. This causes an arc to occur between the contacts, as shown in step 2 of Figures 2 and 3. In this state, the arc becomes a metal-phase arc maintained in the metal vapor.

[0027] At this time, as shown in Figure 2, if air, specifically oxygen, gets between the contacts, the arc changes to a gas phase arc that continues under the influence of the ambient gas, as shown in step 3 of Figure 3. This causes the surfaces of both contacts to oxidize and become rougher, as shown in step 4 of Figure 3. These causes the contact resistance between the contacts to increase, as shown in step 5 of Figure 3, and the voltage drop between the contacts when the contacts are turned on.

[0028] This gaseous arc occurs when the metallic arc changes to a gaseous arc when air enters between the contacts. Therefore, it is necessary to suppress the change to a gaseous arc in order to reduce the voltage drop between the contacts.

[0029] Here, the change to a gaseous phase arc occurs when the voltage between the contacts is high or the current flowing through the contacts is high. Conventionally, to ensure proper contact conduction, the voltage applied to the contacts and the current flowing through the contacts were set to 14 V and 20 A, respectively, when the contacts were turned on during contact running. However, it has been confirmed that proper contact conduction can be achieved even when these values ​​are reduced. After extensive research, the inventors have confirmed that the change to a gaseous phase arc can be suppressed if the voltage applied to the contacts is 8 V or less or the current flowing through the contacts is 0.3 A or less when the contacts are turned on during contact running.

[0030] Therefore, in this embodiment, the voltage of the first power supply 10 is set to, for example, 8 V, and the voltage applied to the contact portion during contact running is set to 8 V or less. Also, by adjusting the resistance value of the load 40, the current flowing through the contact portion at this time is set to 0.3 A or less.

[0031] To prevent the arc from changing to a gaseous phase arc, it is sufficient to satisfy either of the following conditions: the voltage applied to the contact during contact running is 8 V or less, and the current flowing through the contact is 0.3 A or less. These are the lowest upper limits that can be applied to the various types of contact materials used for the contact, but the upper limits will differ depending on the type of contact.

[0032] The "voltage applied to the contacts during contact running" of 8 V or less is intended to prevent a transition to a gaseous arc. Therefore, it preferably refers to the voltage applied to the contacts when the movable contact 2 and the fixed contact 3 separate during contact running. Specifically, the voltage applied to the contacts when the movable contact 2 and the fixed contact 3 separate during contact running refers to the voltage when the contacts separate during contact running and an arc occurs between them. The arc between the contacts refers to a metallic arc if there is no transition from a metallic arc to a gaseous arc. However, if a transition to a gaseous arc occurs, it refers to both a metallic arc and a gaseous arc. Furthermore, if a current flows between the contacts when they are separated during contact running, an arc is considered to have occurred. If no current flows between the contacts, an arc is considered to have occurred. In this embodiment, since the maximum voltage applied to the contacts is 8 V or less, the voltage applied to the contacts when the movable contact 2 and the fixed contact 3 separate during contact running is also 8 V or less.

[0033] Specifically, when Ag is used as the contact material, the change to a gaseous phase arc can be suppressed if either the voltage applied to the contact portion during running contact is 8 V or less and the current flowing through the contact portion is 0.3 A or less. In contrast, when Cu is used as the contact material, the voltage applied to the contact portion during running contact can be greater than 8 V and the current flowing through the contact portion can be greater than 0.3 A. Specifically, when Cu is used as the contact material, the change to a gaseous phase arc can be suppressed if either the voltage applied to the contact portion during running contact is 12 V or less and the current flowing through the contact portion is 0.5 A or less.

[0034] The change to a gaseous arc can be suppressed if either the voltage applied to the contact during running contact is 8 V or less or the current flowing through the contact is 0.3 A or less, but it is undesirable for the other value to be too large. Specifically, the inventors' extensive research has yielded the following results: For example, compared to a case in which the voltage applied to the contact during running contact is 14 V and the current flowing through the contact is 20 A, regardless of the contact material, when the voltage applied to the contact during running contact is 8 V or less, the change to a gaseous arc can be suppressed at least up to a current flowing through the contact of 20 A. Furthermore, when the current flowing through the contact during running contact is 0.3 A or less, the change to a gaseous arc can be suppressed at least up to a voltage applied to the contact of 28 V, and when the applied voltage is 14 V or less, the change to a gaseous arc can be suppressed even more effectively.

[0035] Furthermore, the voltage applied to the contacts and the current flowing through the contacts during contact running should be values ​​that allow for accurate conduction between the contacts during contact running. The lower limit of these values ​​is determined by the structure of the mechanical relay 1, but it is sufficient if the voltage applied to the contacts is at least 0.02 V and the current flowing through the contacts is at least 0.1 A.

[0036] The more contacts are run, the greater the oxidation and surface roughness of the contacts become. However, regardless of the number of runs, satisfying the above conditions can prevent the arc from changing to a gaseous phase arc. Of course, a change to a gaseous phase arc can occur due to various factors, but by performing contact running under settings that satisfy the above conditions, the arc is almost completely prevented from changing to a gaseous phase arc. After the contact running, a mechanical relay 1 of the desired quality can be obtained.

[0037] Using such a contact running device, contact running is performed based on the following running method.

[0038] First, mechanical relay 1 is attached to the contact running device. Specifically, terminal 5 connected to movable contact 2 is connected to first power source 10, and terminal 6 connected to fixed contact 3 is connected to load 40. Terminals 7 and 8 at both ends of excitation coil 4 are connected to second power source 20 and coil drive switch 30, respectively. Then, coil drive switch 30 is controlled to turn on and off by inputting a coil drive signal from a control device (not shown), for example, a square wave signal with an on-off cycle with an on time of 7.5 ms and an off time of 7.5 ms.

[0039] As a result, when the coil drive switch 30 is turned on, a magnetic attractive force is generated from the excitation coil 4. Then, the movable contact 2 is moved toward and contacts the fixed contact 3, turning the contact portion on and supplying current from the first power source 10 to the load 40 through the contact portion. When the coil drive switch 30 is switched from the on state to the off state, the magnetic attractive force from the excitation coil 4 is released. Then, the movable contact 2 moves away from the fixed contact 3, turning the contact portion off and stopping the supply of current from the first power source 10 to the load 40. This is repeated a number of times, for example, 100 times. This allows the operation and quality of the mechanical relay 1 to be checked.

[0040] In this case, the contact running device of this embodiment ensures that the voltage applied to the contacts during contact running is 8 V or less, or that the current flowing through the contacts is 0.3 A or less. This prevents the arc from changing into a gas phase arc even if air enters between the contacts when the contacts separate while voltage is applied between them during contact running. This makes it possible to prevent an increase in the contact resistance of the contacts.

[0041] (Second embodiment) The second embodiment will be described. This embodiment is different from the first embodiment in that the circuit configuration of the contact running device is changed, but other aspects are the same as the first embodiment, so only the differences from the first embodiment will be described.

[0042] As shown in FIG. 4, the contact running device of this embodiment includes a voltage limiting element 70 connected in parallel to the load 40. The voltage limiting element 70 limits the voltage applied to the contacts when the contacts separate during contact running to a predetermined voltage value, specifically, 8 V or less, below the voltage at which a transition to a gaseous arc occurs. In this example, the voltage limiting element 70 is configured as a capacitor. However, the voltage limiting element 70 may be any other element capable of limiting the voltage applied to the contacts to a predetermined voltage value or less. For example, the voltage limiting element 70 may be a diode arranged with its cathode facing upstream and its anode facing downstream.

[0043] In this way, when the voltage-limiting element 70 is connected in parallel to the load 40, the voltage applied to the contacts can be limited to a predetermined voltage value or less when the contacts are separated during contact running. Specifically, if the voltage-limiting element 70 is configured with a capacitor, the capacitor is charged when the contacts are connected during contact running. In this embodiment, the capacitor is charged to the voltage of the first power source 10. As a result, the potential on the low side of the contacts rises to the charging voltage of the capacitor, and when the contacts are separated during contact running, the voltage applied to the contacts drops. In other words, rather than the voltage due to the voltage division between the contact resistance and the load 40, a voltage lower than that is applied to the contacts. Therefore, the voltage applied to the contacts can be limited, making it possible to suppress the transition to a gaseous phase arc.

[0044] Furthermore, when the voltage applied to the contact portion can be limited in this manner, the voltage of the first power supply 10 can be higher than in the first embodiment. For example, the voltage of the first power supply 10 is set to 14±1 V. This makes it possible to suppress a transition to a gaseous phase arc even when a voltage that would not be able to suppress the transition to a gaseous phase arc were applied to the contact portion without the voltage limiting element 70. Specifically, when the contacts of the contact portion are separated and an arc is generated between them during contact running, the voltage between the contacts is limited to 8 V or less by the action of the voltage limiting element 70, as in the first embodiment. Therefore, even if a higher voltage is applied during contact running or the resulting current value becomes higher, a transition to a gaseous phase arc can be suppressed, and an increase in the contact resistance of the contacts can be suppressed.

[0045] (Other embodiments) Although the present disclosure has been described based on the above-described embodiment, it is not limited to the embodiment and encompasses various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0046] For example, the circuit configuration of the contact running device described in each of the above embodiments is merely an example, and other elements may be included, or the configuration may be such that either or both of the ammeter 50 and the voltmeter 60 are not included.

[0047] Furthermore, although a resistor load is taken as an example of the load 40 here, it is not limited to a resistor load and may be an inductive load or a combination of a resistor load and an inductive load.

[0048] Furthermore, in each of the above embodiments, the circuit configuration is such that the mechanical relay 1 is disposed on the higher side of the load 40. This is also one example, and a structure in which the load 40 is disposed on the higher side of the mechanical relay 1, or a structure in which the load 40 is disposed separately on the high side and low side of the mechanical relay 1 may also be used.

[0049] Furthermore, in the above embodiments, the movable contact 2 and the fixed contact 3 are made of, for example, Ag or Cu, but they may be made of other contact materials such as palladium. For example, even if the movable contact 2 and the fixed contact 3 are made of palladium, if the voltage applied between the contacts at the contact portion during contact running is 8 V or less, or if the current flowing through the contact portion when the contact portion is turned on is 0.3 A or less, the change to a gas phase arc can be suppressed.

[0050] Furthermore, in each of the above embodiments, the mechanical relay 1 shown in FIG. 1 etc. is a 12V relay, but the mechanical relay 1 may be a 12V relay or a 24V relay.

[0051] It goes without saying that in each of the above embodiments, the elements constituting the embodiments are not necessarily essential unless they are specifically stated as essential or are clearly considered essential in principle. Furthermore, in each of the above embodiments, when numerical values ​​such as the number, values, amounts, and ranges of the components of the embodiments are mentioned, they are not limited to the specific numbers unless they are specifically stated as essential or are clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., unless they are specifically stated or are clearly limited to a specific shape, positional relationship, etc. in principle. [Explanation of symbols]

[0052] 1... mechanical relay, 2... moving contact, 3... fixed contact, 4... exciting coil, 5-8... terminals, 10... first power supply, 20... second power supply, 30... coil drive switch, 40... load, 50... ammeter, 60... voltmeter, 70... voltage limiting element

Claims

1. A contact running device for turning on and off a contact part of a mechanical relay (1) having a contact part including a movable contact (2) and a fixed contact (3) and an excitation coil (4) that generates a magnetic attraction force to control the on / off of the contact part, and for causing a current to flow in the contact part when the mechanical relay is turned on, a first power source (10) that applies a voltage to the contact portion; a second power source (20) that supplies current to the excitation coil; a drive switch (30) that controls on / off of current supply from the second power source to the excitation coil; a load (40) connected to the contact portion to be supplied with a current flowing through the contact portion when the contact portion is turned on; A contact running device in which the voltage applied between the contacts in the contact portion is 8 V or less, or the current value of the current flowing through the contact portion when the contact portion is turned on is 0.3 A or less.

2. 2. The contact running device according to claim 1, wherein the voltage applied between the contacts in the contact portion is 8 V or less, and the current value of the current flowing through the contact portion when the contact portion is turned on is 20 A or less.

3. 2. The contact running device according to claim 1, wherein the current value of the current flowing through the contact portion when the contact portion is turned on is 0.3 A or less, and the voltage applied between the contacts in the contact portion is 14 V or less.

4. 2. The contact running device according to claim 1, wherein the current value of the current flowing through the contact portion when the contact portion is turned on is 0.3 A or less, and the voltage applied between the contacts in the contact portion is 28 V or less.

5. At least the surfaces of the movable contact and the fixed contact in the contact portion are made of Ag, 2. The contact running device according to claim 1, wherein the voltage applied between the contacts in the contact portion is 8 V or less, and the current value of the current flowing through the contact portion when the contact portion is turned on is 0.3 A or less.

6. At least the surfaces of the movable contact and the fixed contact in the contact portion are made of Cu, 2. The contact running device according to claim 1, wherein the voltage applied between the contacts in the contact portion is 8 V or less, and the current value of the current flowing through the contact portion when the contact portion is turned on is 0.3 A or less.

7. 5. The contact running device according to claim 1, wherein the surfaces of at least the movable contact and the fixed contact in the contact portion are made of Ag or Cu.

8. 7. The contact running device according to claim 1, further comprising a voltage limiting element (70) connected in parallel to the load and limiting the voltage applied to the contact portion to 8 V or less when the movable contact and the fixed contact are separated during contact running.

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