Electromagnetic relay protection system

Abstract

To provide a protection system for an electromagnetic relay for preventing conduction failure of a contact point due to freezing of the electromagnetic relay with a simple configuration.SOLUTION: A protection system 10 for an electromagnetic relay prevents, in advance, occurrence of connection failure due to freezing of the electromagnetic relay (a positive electrode side electromagnetic relay 18 and a negative electrode side electromagnetic relay 22) mounted on a battery pack 12 of a vehicle, and includes: temperature detection means 34 for sequentially measuring and storing ambient temperature of a place where the electromagnetic relay is installed; cooling means 30 for cooling a power line 24 connected to a fixed terminal of the electromagnetic relay; and a control unit 32 for operating the cooling means 30 to cool the power line 24 when it is determined that the electromagnetic relay may freeze based on temperature information from the temperature detection means 34.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a protection system for an electromagnetic relay, and more particularly to a protection system for an electromagnetic relay that prevents poor continuity of contacts due to freezing. [Background technology]

[0002] Electromagnetic relays are often used as a switching method to supply power to electronic devices, power supplies, vehicles, etc., when starting up devices or equipment. Inside the housing of an electromagnetic relay are fixed terminals for connecting the circuit, movable terminals, and an excitation coil for moving the movable terminal. A circuit is connected, i.e., the power supply and the electrical load are connected, by supplying a voltage to the excitation coil and moving the movable terminal to contact the fixed terminal.

[0003] In an electromagnetic relay configured in this manner, heat generated by the excitation coil and terminal contacts generates water vapor inside the electromagnetic relay housing, and if the ambient temperature of the electromagnetic relay falls below freezing, condensation forms on the fixed terminals, and the condensation freezes, causing poor contact conductivity.

[0004] 5 is an explanatory diagram of a contact conduction failure that occurs when the contacts of an electromagnetic relay freeze. A power line, for example, bus bars 23 and 24, is connected to a fixed terminal 40 of the electromagnetic relay 18 (22). When a voltage is supplied to an excitation coil (not shown), the movable terminal 38 moves toward the fixed terminal 40 as indicated by arrow A, and the contact 40a of the fixed terminal 40 and the contact 38a of the movable terminal 38 come into contact.

[0005] When voltage is supplied to the excitation coil, the excitation coil heats up, and when current is applied, the terminal contacts heat up, causing water vapor to be present inside the housing 44. In this situation, if the ambient temperature where the electromagnetic relay is installed drops, condensation occurs over the entire contact 40a. If the ambient temperature drops further and falls below freezing, the condensation freezes, causing poor conductivity. In other words, due to freezing, ice particles 42 are present between the contact 38a of the movable terminal 38 and the contact 40a of the fixed terminal 40, resulting in poor conductivity between the contact 40a of the fixed terminal 40 and the contact 38a of the movable terminal 38.

[0006] To address this problem of freezing, Patent Document 1 provides a vibration generating means for generating vibrations in the housing or in the area inside the housing where freezing has occurred. When it is determined that freezing has occurred inside the housing of the electromagnetic relay, the vibrations generated by the vibration generating means are transmitted to the fixed terminals or the like to remove the freezing. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-165406 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0008] The method disclosed in Patent Document 1 requires the addition of, for example, a vibration motor to generate vibrations, which may increase the cost of the electromagnetic relay and may affect surrounding components due to the generated vibrations.Furthermore, there is a concern that abnormal noise may be generated.

[0009] Furthermore, the most important point to consider is that with the method disclosed in Patent Document 1, if a conduction failure occurs due to freezing, it takes time to unfreeze the circuit, and the electromagnetic relay cannot be turned on immediately.

[0010] The present invention has been made in view of the above problems, and an object of the present invention is to provide a protection system for an electromagnetic relay that has a simple configuration and eliminates the problem of freezing of the electromagnetic relay. [Means for solving the problem]

[0011] In order to achieve the above object, the protection system for an electromagnetic relay according to claim 1 comprises: In a protection system for an electromagnetic relay that prevents connection failures caused by freezing of an electromagnetic relay mounted on a vehicle, a temperature detection means for successively measuring and storing the environmental temperature of the location where the electromagnetic relay is installed; a cooling means for cooling a power line connected to the fixed terminal of the electromagnetic relay; a control unit that activates the cooling unit to cool the power line when it determines that there is a risk of the electromagnetic relay freezing based on the temperature information from the temperature detection unit; The present invention is characterized by having the following.

[0012] According to this configuration, when it is determined that an environmental temperature at which freezing will occur will occur in an electromagnetic relay that is not currently freezing, the power line connected to the fixed terminal of the electromagnetic relay is cooled, thereby suppressing freezing at the contact portion of the fixed terminal with the movable terminal of the electromagnetic relay and preventing the occurrence of a connection failure. That is, although the power line is connected to the fixed terminal of the electromagnetic relay, this connection portion is on the base end side of the fixed terminal, i.e., on the side opposite to the side that contacts the movable terminal.

[0013] Therefore, when the power line is cooled by the cooling means, the base end of the fixed terminal is cooled by a temperature gradient that is steeper than that caused by natural cooling due to the ambient temperature. This has the effect of concentrating condensation and freezing on the base end of the fixed terminal. In other words, the occurrence of condensation and freezing at the contact point with the movable terminal is ensured to be lower than that caused by a natural drop in ambient temperature, and poor conductivity due to freezing can be avoided.

[0014] In order to achieve the above object, the protection system for an electromagnetic relay according to claim 2 comprises: a meteorological information storage means for receiving and storing weather forecast information including temperature information; The control unit determines whether the electromagnetic relay is at risk of freezing, The temperature change information measured sequentially by the temperature detection means from a predetermined measurement start time to the current time and the temperature change prediction information from the present onward based on the weather forecast information are used to predict the temperature change thereafter, and a judgment is made based on the prediction as to whether the electromagnetic relay will reach a freezing temperature.

[0015] With this configuration, the risk of freezing can be determined by using both the information on the transition of actual temperature change in the electromagnetic relay and the information on the forecast of temperature change from the present onward based on weather forecast information, thereby achieving a more reliable protective action. That is, if the information on the transition of actual temperature change predicts freezing, the power line cooling operation is immediately initiated. Furthermore, even if the information on the transition of actual temperature change indicates that the electromagnetic relay will not reach the freezing temperature, if the weather forecast information predicts a sudden drop in temperature due to a sudden change in weather, the cooling operation can be performed. This allows for more stable relay protection that takes weather forecast information into account.

[0016] The protection system for an electromagnetic relay according to claim 3 is the protection system for an electromagnetic relay according to claim 1 or 2, The operation of the cooling means is In addition to the judgment that there is a risk of the electromagnetic relay freezing, The electromagnetic R The temperature of the condensation bath is set when the temperature satisfies the temperature conditions for condensation to occur.

[0017] With this configuration, the cooling means determines whether the electromagnetic relay is likely to freeze and RSince the cooling means is activated when the temperature of the relay satisfies the temperature conditions for condensation to occur, it is possible to operate the cooling means only when there is a high possibility that condensation will occur and freeze. In other words, in a situation where condensation will not occur, there will be no connection failure of the relay due to freezing, so it is possible to cool the power line only when it is actually necessary.

[0018] The protection system for an electromagnetic relay according to claim 4 is the protection system for an electromagnetic relay according to any one of claims 1 to 3, The cooling is performed at a temperature gradient of 10°C to 40°C / hour.

[0019] This allows for cooling at a temperature gradient of 10°C to 40°C per hour, which is steeper than the natural drop in environmental temperature, and effectively concentrates condensation and freezing on the base end side of the fixed terminal. In other words, it is possible to increase condensation and freezing on the base end side of the fixed terminal and effectively reduce condensation on the side that comes into contact with the movable terminal. Therefore, poor conductivity due to freezing can be reliably prevented. [Effects of the Invention]

[0020] According to the electromagnetic relay protection system of the present invention, when it is determined that there is a risk of the electromagnetic relay freezing, the power line connected to the fixed terminal is cooled to make the base end side of the fixed terminal lower in temperature than the connection end side (tip side), thereby reliably preventing freezing on the connection end side and avoiding the problem of poor conduction of the electromagnetic relay. Therefore, a highly reliable electromagnetic relay can be provided, and the performance of a vehicle equipped with it is guaranteed. [Brief explanation of the drawings]

[0021] [Figure 1] 1 shows a schematic configuration diagram of an electromagnetic relay protection system according to the present invention. [Figure 2] 3 shows the control flow of the electromagnetic relay protection system of the present invention. [Figure 3]10 is an explanatory diagram of predicted temperature transitions in the electromagnetic relay protection system of the present invention. FIG. [Figure 4] 1 is an explanatory diagram showing how a continuity defect is resolved in the protection system for an electromagnetic relay according to the present invention; [Figure 5] 1 is an explanatory diagram of a problem of poor conduction due to freezing in a conventional electromagnetic relay. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, one embodiment of the electromagnetic relay protection system of the present invention will be described in detail with reference to the drawings.

[0023] 1 is a schematic diagram of an electromagnetic relay protection system according to one embodiment of the present invention. The electromagnetic relay protection system 10 includes a battery pack 12 that houses a battery 14, a junction box 16, a control unit 32, etc., and an external unit 36 connected via an in-vehicle network 50.

[0024] The battery pack 12 also includes a temperature detection means 34, a positive terminal 26, and a negative terminal 28. The junction box 16 includes a positive electromagnetic relay 18, a negative electromagnetic relay 22, and a precharge relay 20. The positive electrode of the battery 14 and the positive electromagnetic relay 16, and the negative electrode of the battery 14 and the negative electromagnetic relay 22 are connected via power lines, for example, bus bars 23.

[0025] Similarly, the positive-side relay 18 in the junction box 16 is connected to the positive-side terminal 26, and the negative-side electromagnetic relay 22 in the junction box 16 is connected to the negative-side terminal 28 via a bus bar 24. The bus bar 23 and the bus bar 24 are of the same material but have different lengths.

[0026] The cooling means 30 is, for example, a Peltier element, and in this embodiment, it is configured to cool both the bus bar 24 between the positive side electromagnetic relay 18 and the positive side terminal 26, and the negative side electromagnetic relay 22 and the negative side terminal 28.

[0027] The temperature detection means 34 measures the temperature inside the battery pack 12, i.e., the environmental temperature where the electromagnetic relay 18 (22) is installed. It is configured to measure the temperature sequentially at predetermined time intervals from a predetermined start time, and store the measured temperature values. The control unit 32 can communicate with an external unit 36 via the in-vehicle network 50 and receive weather forecast information including temperature information. The obtained weather forecast information is stored in the weather information storage means 33. The control unit 32 is also configured to determine whether the electromagnetic relay 18 (22) will reach a freezing temperature, refer to the measured temperatures stored in the temperature detection means 34, control the cooling means 30, and so on.

[0028] 2 is a control flow diagram relating to the electromagnetic relay control method of the present invention. In this embodiment, the risk of the electromagnetic relay freezing is determined using both information on the actual temperature change transition in the electromagnetic relay and information on the temperature transition forecast from the present onwards based on weather forecast information.

[0029] The control flow begins when the vehicle's ignition is turned off after use (step S1). That is, in the most preferred embodiment of the present invention, for example, after use of the vehicle in a cold region is finished, if freezing is expected by the next morning, anti-freezing control is performed overnight, so that the vehicle can be used immediately in the early morning without the problem of poor conduction of the electromagnetic relay due to freezing.

[0030] Returning to the flow of Fig. 2, meteorological forecast information such as a weather forecast is obtained from the external unit 36 using the in-vehicle network 50 (step S2), and stored in the meteorological information storage means 33. Then, based on the temperature measured by the temperature detection means 34, the temperature change inside the battery pack is predicted (step S3). This prediction of the temperature change inside the battery pack 12 (step S3) is performed by the control unit 32 based on a series of temperature measurements made by the temperature detection means 34 up to the present.

[0031] FIG. 3 is an explanatory diagram of predicted temperature transitions in the electromagnetic relay protection system of the present invention. The horizontal axis represents time, and the vertical axis represents temperature. There are two curves, and the upper curve represents the temperature transition curve (actual measured values) for one day, for example, the last time the vehicle was used. The lower curve relates to the current day, and the measured values up to the present (indicated by a circle) are shown as a solid line, and the predicted temperature transition thereafter is shown as a dashed line. In other words, the dashed line represents the predicted temperature transition of the electromagnetic relay from the present time onwards. T1 on the vertical axis is the condensation onset temperature, and T2 is the freezing onset temperature.

[0032] As mentioned above, this prediction is made by the control unit 32 based on a series of temperature measurements made up to the present by the temperature detection means 34, but the prediction may be made, for example, using artificial intelligence (AI) or by finding a regression curve of the temperature measurements. The temperature prediction shown in Figure 3 indicates that from now on, the temperature will be below the condensation start temperature and freezing start temperature.

[0033] Returning to the flow of Fig. 2, next, the control unit 32 determines whether the electromagnetic relay 18 (22) will reach a freezing temperature, i.e., the possibility of freezing (step S4). This determination is made based on the predicted temperature transitions shown in Fig. 3 and weather information obtained from the external unit 36. That is, if freezing is predicted based on the information on the transition of actual temperature change, it is determined that there is a risk of freezing. Furthermore, even if it is determined based on the information on the transition of actual temperature change that the electromagnetic relay will not reach a freezing temperature, if the weather forecast information predicts a sudden drop in temperature due to a sudden change in weather, it is determined that there is a risk of freezing.

[0034] If it is determined that there is no possibility of freezing (step S4, No), the flow ends. If it is determined that there is a possibility of freezing (step S4, Yes), the temperature inside the battery pack 12 is measured (step S5). If the electromagnetic relay 18 (22) reaches a temperature at which condensation occurs (step S6, Yes), that is, if the temperature condition for condensation to occur is met, anti-freeze control is executed (step S7).

[0035] The temperature at which condensation occurs varies depending on the volume of the electromagnetic relay housing, the amount of moisture in the housing, the heat generation temperature of the excitation coil, etc., but in this embodiment, the temperature at which condensation occurs is assumed to be known in advance through experiments, analysis, etc.

[0036] The anti-freeze control in step S7 is to cool the bus bars 24 in the battery pack 12 by the cooling means 30. When the cooling continues and the temperature inside the battery pack 12 drops below 0°C, specifically -5°C (step S8, Yes), the anti-freeze control is turned off (step S9). Then, the flow ends.

[0037] If the temperature inside the battery pack 12 does not reach a temperature at which condensation occurs (step S6, No), i.e., if the temperature condition for condensation occurrence is not satisfied, the process returns to step S5, where the temperature inside the battery pack 12 is measured in step S5. Here, if the temperature inside the battery pack 12 does not drop to a temperature at which condensation occurs (step S6, No), the process continues to loop through steps S5 and S6. However, this state will eventually reach a temperature at which condensation occurs (step S6, Yes), and anti-freeze control will be performed (step S7), so the process does not fall into an infinite loop. Note that, taking into consideration that the environmental temperature may change and there may be no risk of the electromagnetic relay freezing, or that the temperature condition for condensation occurrence may not be satisfied, steps S5 and S6 may be performed for a predetermined time and then the flow may end.

[0038] During anti-freeze control, the busbars 24 are cooled at a temperature gradient of 10°C to 40°C per hour. The optimal cooling temperature gradient varies depending on factors such as the size of the electromagnetic relay, but good results can generally be achieved within this range. This cooling allows condensation and freezing to occur efficiently on the base end side of the fixed terminal.

[0039] 4 is an explanatory diagram of the effect of the electromagnetic relay protection system of the present invention. As described above, when there is a risk of freezing and the temperature inside the battery pack drops to a temperature at which condensation occurs, the bus bar 24 is cooled by the cooling means 30.

[0040] The bus bar 24 is made of, for example, a copper plate and has good thermal conductivity, so that the base end B connected to the bus bar 24 at the contact 40a of the fixed terminal 40 is cooled first, causing condensation to form. Because the amount of moisture inside the housing 44 of the electromagnetic relay 18 (22) is approximately constant, if a lot of condensation forms at the base end B connected to the bus bar 24, the amount of condensation that forms at the tip end S, i.e., the side of the movable terminal 38, will be relatively less. In other words, by cooling the bus bar 24 using a temperature gradient that is steeper than natural cooling, more condensation forms at the base end B of the contact 40a of the fixed terminal 40 and less condensation forms at the tip end S.

[0041] In this state, when the ambient temperature reaches a temperature at which freezing occurs, almost no icing occurs on the tip side S of the contact 40a of the fixed terminal 40a, and good contact is made between the contact 38a of the movable terminal 38 and the contact 40a of the fixed terminal 40. In other words, ice particles 42 that would prevent conduction are not present between the contact 40a of the fixed terminal 40 and the contact 38a of the movable terminal 38, and poor conduction does not occur.

[0042] The bus bars 23, 23 connecting the battery 14 and the electromagnetic relay 18 (22) are shorter than the bus bars 24, 24 connecting the electromagnetic relay 18 and the positive terminal 26 and negative terminal 28, and therefore there is less of a problem with freezing, so no cooling means is installed, but cooling means 30 may also be installed on the bus bars 23.

[0043] According to the electromagnetic relay protection system of the present invention, when the measured environmental temperature of the location where the electromagnetic relay 18 (22) is installed predicts that the electromagnetic relay 18 (22) may freeze, the bus bar 24 is cooled. When the bus bar 24 is cooled, the contacts 40a of the fixed terminal 40 connected to it will condense more on the base end side S connected to the bus bar 24, and relatively less on the side (tip side S) that contacts the contacts 38a of the movable terminal 30. Therefore, even if the temperature drops and freezing occurs, ice 42 that could cause poor conductivity will not form at the contact point between the fixed terminal 40 and the movable terminal 38, and the electromagnetic relay 18 (22) can be immediately turned on.

[0044] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, although a Peltier element is used as the cooling means 30, this is not limiting. Although only the bus bar 24 between the junction box 16 and the terminals 26, 28 of the battery pack is cooled, all bus bars may be cooled. [Explanation of symbols]

[0045] 10 Electromagnetic relay protection system 12 Battery pack 14 Batteries 16 Junction Box 18 Positive side electromagnetic relay 20 Precharge relay 22 Negative side electromagnetic relay 23, 24 Busbar (power line) 26 Positive terminal 28 Negative terminal 30 Peltier element (cooling means) 32 Control section 33 Meteorological information storage means 34 Temperature detection means 36 External Unit 38 Movable terminal 38a Movable terminal contact 40 fixed terminal 40a Fixed terminal contact 42 Ice particles 50 In-vehicle network A Moving direction of the movable terminal B Base end of fixed terminal contact S Tip side of fixed terminal contact

Claims

1. In a protection system for an electromagnetic relay that prevents connection failures caused by freezing of an electromagnetic relay mounted on a vehicle, a temperature detection means for successively measuring and storing the environmental temperature of the location where the electromagnetic relay is installed; a cooling means for cooling a power line connected to the fixed terminal of the electromagnetic relay; a control unit that activates the cooling unit to cool the power line when it determines that there is a risk of the electromagnetic relay freezing based on the temperature information from the temperature detection unit; 1. A protection system for an electromagnetic relay comprising:

2. a meteorological information storage means for receiving and storing weather forecast information including temperature information; The control unit determines whether the electromagnetic relay is at risk of freezing, 2. The protection system for an electromagnetic relay according to claim 1, wherein the protection is performed by predicting the temperature change thereafter using information on the change in temperature successively measured by the temperature detection means from a predetermined measurement start time to the current time and information on the temperature change prediction from the present onward based on the weather forecast information, and determining whether the temperature change will reach a temperature at which the electromagnetic relay freezes based on the prediction.

3. The operation of the cooling means is In addition to the judgment that there is a risk of the electromagnetic relay freezing, 3. The protection system for an electromagnetic relay according to claim 1, wherein the protection is performed when the temperature of the electromagnetic relay satisfies a temperature condition that causes condensation.

4. 4. The protection system for an electromagnetic relay according to claim 1, wherein the cooling is performed at a temperature gradient of 10° C. to 40° C. per hour.

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