Method for driving electromagnetic relays

Abstract

This invention provides a method for driving a 5-pole electromagnetic relay that can suppress the occurrence of freezing on the NC contact side. [Solution] A method for driving a 5-pin electromagnetic relay, wherein when the movable contact and the first fixed contact are in contact when the relay is ON, the ambient temperature of the electromagnetic relay is obtained, and when the ambient temperature reaches a predetermined temperature at which freezing may occur on the second fixed contact, the relay operation is instantaneously turned OFF at a predetermined timing to bring the movable contact into contact with the second fixed contact, and then the relay operation is immediately returned to ON.

Description

Technical Field

[0001] The present disclosure relates to a method for driving an electromagnetic relay.

Background Art

[0002] Patent Document 1 discloses a control device for controlling an electromagnetic relay (electromagnetic relay). In this Patent Document 1, when conditions for ice formation on the fixed contact are satisfied when the relay operation is OFF, the ice formed on the fixed contact is crushed by intermittently performing ON of the relay operation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an electromagnetic relay with a 5-pole terminal, there are a normally closed fixed contact (hereinafter referred to as "NC contact") with which the movable contact contacts when the relay operation is OFF, and a normally open fixed contact (hereinafter referred to as "NO contact") with which the movable contact contacts when the relay operation is ON. Therefore, when using an electromagnetic relay with a 5-pole terminal in an environment where ice formation is likely to occur, countermeasures against ice formation are required for both the NC contact and the NO contact.

[0005] The technique described in Patent Document 1 is aimed at crushing ice formed on the NO contact when the relay operation is OFF, assuming an electromagnetic relay with a 4-pole terminal. Therefore, even if the technique described in Patent Document 1 is applied to an electromagnetic relay with a 5-pole terminal, ice formation on the NC contact side cannot be suppressed.

[0006] This disclosure has been made in view of the above-mentioned problems, and aims to provide a method for driving an electromagnetic relay that can suppress the occurrence of freezing on the NC contact side in an electromagnetic relay with 5 terminals. [Means for solving the problem]

[0007] To solve the above problems, one aspect of the disclosed technology is a method for driving a five-pin electromagnetic relay, wherein the ambient temperature of the electromagnetic relay is obtained when the movable contact and the first fixed contact are in contact when the relay operation is ON, and when the ambient temperature reaches a predetermined temperature at which freezing may occur on the second fixed contact, the relay operation is instantaneously turned OFF at a predetermined timing to bring the movable contact into contact with the second fixed contact, and then the relay operation is immediately returned to ON. [Effects of the Invention]

[0008] According to the electromagnetic relay driving method of this disclosure, if there is a risk of ice forming on the second fixed contact (NC contact) while the relay is ON, the relay operation is switched from OFF to ON instantaneously to strike the movable contact against the second fixed contact and break up the ice. As a result, in an electromagnetic relay with 5 terminals, the occurrence of ice forming on the NC contact when the relay is ON can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram illustrating an example of the structure of an electromagnetic relay according to one embodiment of this disclosure. [Figure 2] A flowchart explaining how to drive an electromagnetic relay. [Figure 3] Diagrams illustrating the state of each fixed and movable contact, illustrating the driving method of an electromagnetic relay. [Modes for carrying out the invention]

[0010] In the five-pole electromagnetic relay described herein, if there is a possibility of ice forming on the NC contact (which is not energized) while the device is being driven by energizing the NO contact, the relay operation is momentarily turned OFF to the extent that it does not interfere with the use of the connecting components. This action causes the movable contact to strike the NC contact, removing the ice. The embodiments of this disclosure will be described in detail below with reference to the drawings.

[0011] <Embodiment> [structure] Figure 1 is a schematic diagram illustrating an example of the structure of an electromagnetic relay 1 according to one embodiment of the present disclosure. The electromagnetic relay 1 illustrated in Figure 1 is a five-pole electromagnetic relay that uses electromagnetic force to open and close electrical contacts. This electromagnetic relay 1 comprises a first fixed contact portion 10, a second fixed contact portion 20, a movable contact portion 30, and a magnetic circuit 40.

[0012] The first fixed contact portion 10 is made of a conductive material. This first fixed contact portion 10 includes a first fixed contact 11 and a terminal 12 electrically connected to the first fixed contact 11. The first fixed contact 11 is an NO contact that contacts the movable contact 31 (described later) when the electromagnetic relay 1 is performing relay operation (relay operation ON), causing the first fixed contact portion 10 and the movable contact portion 30 to become electrically connected. For example, a power supply is connected to the terminal 12.

[0013] The second fixed contact portion 20 is made of a conductive material. This second fixed contact portion 20 includes a second fixed contact 21 and a terminal 22 electrically connected to the second fixed contact 21. The second fixed contact 21 is an NC contact that contacts the movable contact 31 (described later) when the electromagnetic relay 1 is not performing relay operation (relay operation OFF), thereby creating a conductive state between the second fixed contact portion 20 and the movable contact portion 30. For example, ground (GND) is connected to the terminal 22.

[0014] The movable contact portion 30 is made of a conductive material. This movable contact portion 30 includes a movable contact 31 positioned between the first fixed contact 11 and the second fixed contact 21, and a terminal 32 electrically connected to the movable contact 31. When the electromagnetic coil 41 is not activated (when the relay is OFF), the movable contact 31 contacts the second fixed contact 21. When the electromagnetic coil 41 is activated (when the relay is ON), a part of the terminal 32 moves (bends, slides, rotates, etc.) so that the movable contact 31 contacts the first fixed contact 11. For example, a device or component (drive component 110) that is driven in conjunction with the power supply from the first fixed contact portion 10 is connected to the terminal 32.

[0015] The magnetic circuit 40 is configured to control the contact point (movement) of the movable contact 31. This magnetic circuit 40 includes an electromagnetic coil 41 that can generate a magnetic force by passing an electric current through it, and terminals 42 and 43 for passing an electric current through the electromagnetic coil 41. If the electromagnetic coil 41 is not energized (relay operation OFF), the magnetic circuit 40 does not exert an attractive force to draw the movable contact 30 towards it. Therefore, the movable contact 31 remains in contact with the second fixed contact 21. On the other hand, when the electromagnetic coil 41 is energized via terminals 42 and 43 (relay operation ON), the magnetic circuit 40 exerts an attractive force to draw the movable contact 30 towards it. Therefore, this attractive force causes the movable contact 30 to move closer to the first fixed contact 10, causing the movable contact 31 to contact the first fixed contact 11, and terminals 12 and 32 to be electrically connected.

[0016] The control of the magnetic circuit 40 by energizing terminals 42 and 43 is performed, for example, by an electronic control unit (ECU) or a microcontroller (control device 120).

[0017] [control] Next, referring further to FIGS. 2 and 3, a driving method performed by the electromagnetic relay 1 according to the present embodiment will be described. FIG. 2 is a flowchart for explaining a processing procedure of driving control of the electromagnetic relay 1 executed by the control device 120. FIG. 3 is a diagram showing an example of states that the first fixed contact 11, the second fixed contact 21, and the movable contact 31 can take in each process of FIG. 2.

[0018] (Step S201) In the normal state, the control device 120 turns off the relay operation and connects the movable contact 31 and the second fixed contact 21 (NC contact). The electromagnetic relay 1 at this time is in the state shown in FIG. 3(a).

[0019] (Step S202) The control device 120 determines whether there is a driving request for the driving component 110 connected to the first fixed contact portion 10. If it is determined that there is a driving request for the driving component 110 (Step S202, Yes), the process proceeds to Step S203. On the other hand, if it is determined that there is no driving request for the driving component 110 (Step S202, No), the process proceeds to Step S201.

[0020] (Step S203) The control device 120 energizes the electromagnetic coil 41 to turn on the relay operation. As a result, the movable contact 31 and the first fixed contact 11 (NO contact) are connected. The electromagnetic relay 1 at this time is in the state shown in FIG. 3(b).

[0021] (Step S204) The control device 120 collects the temperature around the electromagnetic relay 1. This ambient temperature may be collected from the temperature sensor if the electromagnetic relay 1 has a temperature sensor, or may be collected from a temperature sensor near the electromagnetic relay 1 mounted on the vehicle when the electromagnetic relay 1 is mounted on the vehicle.

[0022] (Step S205) The control device 120 determines whether the ambient temperature has reached the expected freezing temperature. This expected freezing temperature is a predetermined temperature at which freezing is expected to occur on the second fixed contact 21 (NC contact), which is not energized when the relay is ON. In the environment of the expected freezing temperature, the electromagnetic relay 1 is shown in Figure 3(c) as ice particles (black circles) have formed on the second fixed contact 21. If it is determined that the ambient temperature has reached the expected freezing temperature (step S205, yes), the process proceeds to step S206. On the other hand, if it is determined that the ambient temperature has not reached the expected freezing temperature (step S205, no), the process proceeds to step S202.

[0023] (Step S206) The control device 120 determines whether or not it is the predetermined timing. This predetermined timing is the timing at which momentarily turning off the relay operation will not interfere with the operation of the drive component 110 connected to the first fixed contact 10. For example, if the drive component 110 is a motor that drives the vehicle's wipers, momentarily turning off the relay operation may cause the wiper's movement to temporarily slow down. Therefore, it is desirable to set the timing of turning off the relay operation to just before or exactly when the wiper changes direction, so as to understand the wiper's operation and not cause any discomfort to the driver. If it is determined that it is the predetermined timing (step S206, yes), the process proceeds to step S207. On the other hand, if it is determined that it is not the predetermined timing (step S206, no), the process waits until the predetermined timing arrives.

[0024] Furthermore, if the drive component 110 connected to the first fixed contact portion 10 is a component that can be forcibly stopped without causing any problems, the control device 120 may omit the decision in step S206.

[0025] (Step S207) The control device 120 performs a momentary OFF of the relay operation. The momentary time for which the relay operation is turned OFF can be set to a length that does not interfere with the operation of the drive component 110 connected to the first fixed contact 10, even if it is performed at a predetermined timing. By turning off the relay operation for just a moment, the ice that has formed on the second fixed contact 21 (NC contact) can be removed before it grows due to the impact and arc discharge caused by the movable contact 31, as well as the melting effect of Joule heating from the current flowing through the second fixed contact 21. As shown in Figure 3(d), when the electromagnetic relay 1 is momentarily turned OFF, the ice particles (indicated by black circles) that had formed on the second fixed contact 21 are removed. When the relay operation is momentarily turned OFF, the process proceeds to step S203 and the relay operation is quickly restored to ON (as shown in Figure 3(b)).

[0026] As with this drive method, if it is determined that there is a possibility of ice forming on the second fixed contact 21 (NC contact) while the electromagnetic relay 1 is ON, the relay operation is instantaneously turned OFF each time to remove the ice. Therefore, when the drive request to the drive component 110 is removed and the relay operation is turned OFF, connection failures caused by ice on the second fixed contact 21 (NC contact) (ice getting stuck) are prevented.

[0027] Furthermore, the movable contact 31 vibrates for a short time (for example, several tens of milliseconds) when it makes contact with the second fixed contact 21 (NC contact). Therefore, by switching the relay operation to ON at the timing of the first rebound after the movable contact 31 makes contact with the second fixed contact 21, after the relay operation has been turned OFF, the connection between the movable contact 31 and the first fixed contact 10 can be restored in the shortest possible time.

[0028] <Effects and Actions> As described above, according to the driving method of the electromagnetic relay 1 according to one embodiment of the present disclosure, if there is a possibility of freezing occurring at the second fixed contact 21 (NC contact) which is not energized while the relay is operating and energizing the first fixed contact 11 (NO contact) to drive the drive component 110, the relay operation is instantaneously turned OFF at a timing that does not affect the operation of the drive component 110, based on the driving state of the drive component 110.

[0029] This operation causes the movable contact 31 to strike and arc discharge the second fixed contact 21 (NC contact), thereby suppressing the formation of ice on the second fixed contact 21 (NC contact). Therefore, a stable connection to the second fixed contact 21 (NC contact) can be established at any time. [Industrial applicability]

[0030] The electromagnetic relay driving method of this disclosure can be used in cases such as when it is desired to suppress the formation of ice on normally closed fixed contacts (NC contacts) when the relay operation is ON in an electromagnetic relay with 5 terminals. [Explanation of Symbols]

[0031] 1 Electromagnetic relay 10 1st fixed contact section 11 1st fixed contact 12 terminals 20 2nd fixed contact section 21 2nd fixed contact 22 terminals 30 Movable contact section 31 Movable contact 32 terminals 40 Magnetic Circuits 41 Electromagnetic coil Terminals 42 and 43 110 Drive components 120 Control device

Claims

1. A method for driving a five-terminal electromagnetic relay, When the relay is ON, the movable contact and the first fixed contact are in contact. The ambient temperature of the electromagnetic relay is obtained, When the ambient temperature reaches a predetermined temperature at which freezing may occur on the second fixed contact, the relay operation is instantaneously turned OFF at a predetermined timing to bring the movable contact into contact with the second fixed contact, and then the relay operation is immediately restored to ON. A method for driving an electromagnetic relay.

2. The predetermined timing is determined based on the driving state of the component connected to the first fixed contact. A method for driving an electromagnetic relay according to claim 1.

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