WO2014077103A1

WO2014077103A1 - Electromagnetic switch

Info

Publication number: WO2014077103A1
Application number: PCT/JP2013/078896
Authority: WO
Inventors: 山田　剛司; 繁彦小俣; 中里　成紀
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2012-11-16
Filing date: 2013-10-25
Publication date: 2014-05-22
Also published as: CN104838464B; JP2014102887A; JP6057677B2; CN104838464A

Abstract

The purpose of the present invention is to make it possible to close a contact of an electromagnetic switch at the front stage of a starting motor even when a weak magnetic field is generated by an electromagnetic solenoid. The electromagnetic switch comprises: a resistor for restricting a current flowing from a battery to the starting motor for starting an engine; a sub-contact which includes a fixed contact and a movable contact arranged in parallel with the resistor; a solenoid coil which generates a first magnetic field in response to energization from the battery; and a movable core surrounded by the solenoid coil. The resistor is arranged in a magnetic circuit of the solenoid coil, which includes a coil portion formed in a coil shape to surround the movable core so that, when a current flows in the coil portion, a second magnetic field is generated in the same direction as the first magnetic field to bring the movable contact into contact with the fixed contact.

Description

Electromagnetic switch

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an electromagnetic switch incorporating a resistor for suppressing current supplied to a starter motor.

In order to suppress the occurrence of a momentary power failure of an electrical component, an electromagnetic switch incorporating a resistor for suppressing a current to be supplied when starting a starting motor is disclosed (see, for example, Patent Document 1).

JP, 2009-224315, A

Due to the limitation of heat generation or volume (number of turns of coil), the magnetic field generated by the electromagnetic solenoid may be weak and it may not be possible to close the contacts of the electromagnetic switch disclosed in Patent Document 1 before the starting motor. .

The electromagnetic switch according to claim 1 comprises: a resistor for suppressing current flowing from the battery to a starter motor for starting the engine; a sub contact including a fixed contact and a movable contact arranged in parallel to the resistor; In an electromagnetic switch comprising a solenoid coil generating a first magnetic field by energization from a coil and a movable core surrounded by the solenoid coil, the resistor is disposed in the magnetic circuit of the solenoid coil and moves the movable contact when current flows. The coil portion is formed in a coil shape surrounding the movable iron core so as to generate a second magnetic field for contacting the fixed contact in the same direction as the first magnetic field.

According to the present invention, even when the magnetic field generated by the electromagnetic solenoid is weak, it is possible to close the contact of the electromagnetic switch in the front stage of the starter motor.

It is a sectional view of an electromagnetic switch. FIG. 5 is an electrical circuit diagram of a starter motor system with an electromagnetic switch connected. It is a figure which shows the shape of the resistor of an electromagnetic switch. It is a time chart at the time of operation of a starter motor system to which an electromagnetic switch in this embodiment is connected. It is a figure which shows the relationship between the suction | attraction force at the time of operation | movement of the sub contact of an electromagnetic switch, and spring reaction force. It is a figure which shows the shape of the resistor of an electromagnetic switch. It is a figure which shows the shape of the resistor of an electromagnetic switch.

The details of the electromagnetic switch according to the embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of an electromagnetic switch 10 in the present embodiment, and FIG. 2 is an electrical circuit diagram of a starter motor system 1. As shown in FIG. 2, the starter motor system 1 includes a motor (starter motor) 2, a pinion 4, a shift lever 5, a main contact 7, a magnet switch 3 and the like. The motor 2 generates the rotational force necessary to start the engine. The pinion 4 transmits its own rotational force to the engine side ring gear 6. The shift lever 5 pushes the pinion 4 in the direction of the ring gear 6 so that the pinion 4 meshes with the ring gear 6. The main contact 7 controls energization of the motor 2 and operation of the shift lever 5. The magnet switch 3 opens and closes the main contact 7 by energization.

The electromagnetic switch 10 is inserted in a circuit from the battery 9 to the main contact 7 of the starter motor system 1, and is configured of a resistor 30, a sub contact 20, an electromagnetic solenoid 11, and the like. Resistor 30 suppresses the current flowing from battery 9 to motor 2. Sub contact 20 includes

fixed contacts

22a and 22b and movable contact 21 arranged in parallel to resistor 30, and shorts resistor 30 in the closed state to energize motor 2 directly from battery 9. . The electromagnetic solenoid 11 performs opening / closing control of the sub contact 20.

The electromagnetic solenoid 11 includes a coil case 18, a solenoid coil 12, a movable iron core 16 surrounded by the solenoid coil 12, a fixed iron core 17 and the like. The coil case 18 has an opening only in the plane intersecting one of the axial directions. The solenoid coil 12 is disposed inside the coil case 18 in a state supported by a bobbin 13 made of resin. The coil case 18, the movable core 16 and the fixed core 17 constitute a magnetic circuit 19. One end of the solenoid coil 12 is connected to an external terminal 14 connected to the controller 8. The other end of the solenoid coil 12 is connected to a fixed core 17. The fixed core 17 is connected to the ground circuit 15 via the coil case 18.

The sub contact 20 is disposed on the opposite side to the magnetic circuit 19 with the fixed core 17 interposed therebetween, and is configured by the movable contact 21, the

fixed contacts

22 a and 22 b, and the contact case 23. The movable contact 21 moves in synchronization with the movable core 16. The contact case 23 holds the

fixed contacts

22a and 22b. The movable contact 21 is held at an initial position in a direction away from the fixed iron core 17 by a contact pressing spring 24. The movable core 16 is held at an initial position in the direction away from the fixed core 17 by the return spring 25.

A first magnetic field generated by energization of the solenoid coil 12 from the battery 9 and a second magnetic field generated by the current flowing from the battery 9 to the motor 2 through the resistor 30 are generated in the same direction. The fixed iron core 17 and the movable iron core 16 are magnetized by the first magnetic field and the second magnetic field, and the attractive force for attracting the movable iron core 16 toward the fixed iron core 17 overcomes the spring reaction force of the return spring 25. Therefore, the movable core 16 is sucked toward the fixed core 17. When the movable contact 21 moving in synchronization with the movable core 16 contacts the

fixed contacts

22a and 22b, the sub contact 20 is closed. When the sub contact 20 is closed, the current flowing from the battery 9 flowing through the resistor 30 to the motor 2 is short-circuited through the sub contact 20, so the suppression of the current flowing from the battery 9 to the motor 2 by the resistor 30 is cancelled. Be done. Thereafter, when the current flowing from the battery 9 to the motor 2 stops and the energization of the solenoid coil 12 is cut off, the movable contact 21 is returned to the initial position by the reaction force of the contact pressing spring 24 and is moved by the reaction force of the return spring 25 As the iron core 16 is returned to the initial position, the sub contact 20 is opened.

FIG. 3 shows the shape of the resistor 30 of the electromagnetic switch 10 in the present embodiment. The resistor 30 is disposed in an air gap (space) surrounded by the outer periphery of the solenoid coil 12 and the coil case 18 in the magnetic circuit 19 of the electromagnetic solenoid 11, as shown in FIG. The periphery of the resistor 30 is covered with a tubular insulating member. The air gap and the insulating member constitute an insulating layer. The resistor 30 has a coil portion 31 formed in a coil shape, and surrounds the solenoid coil 12 and the movable core 16 via the insulating layer. Both

ends

32a and 32b of the resistor 30 are connected to the

fixed contacts

22a and 22b, respectively. The direction of the second magnetic field generated by the current flowing through the coil portion 31 of the resistor 30 when the resistor 30 is energized corresponds to the direction of the first magnetic field generated by the solenoid coil 12.

In order for the amount of heat transfer from the resistor 30 to the coil case 18 to be larger than the amount of heat transfer from the resistor 30 to the solenoid coil 12, the resistor 30 is disposed closer to the coil case 18 in the air gap described above. Ru. By arranging in this manner, the solenoid coil 12 and the parts around it (for example, the bobbin 13) are less susceptible to thermal damage. Further, the sub contact 20 can not be closed, and when the large current for driving the motor 2 is continuously supplied to the resistor 30, the electromagnetic solenoid 11 may become inoperable due to the heat generation of the resistor 30. . In order to prevent this, the time T _R [s] from the start of energization of the resistor 30 to melting and the time for thermal damage that any of the components of the electromagnetic solenoid 11 excluding the resistor 30 become inoperable The resistor 30 is set such that T _S [s] satisfies T _R <T _S. The electrical resistivity [[Ω m], the volume specific heat c [J / (m ³ K)], the cross sectional area A [m ² ], and the amount of heat dissipation in the calorific value of the resistor 30 through which the average current I [A] flows The heat release rate α indicating the ratio, the temperature θ ₀ [° C.] before energization, the melting temperature θ _R [° C], and the time T _R [s] from the start of energization of the resistor 30 to the melting are expressed by Equation (1) Fulfill.
^{{Ρ × I 2 × (1} -α) / (c × A 2)} × T R = θ R -θ 0 (1)

An example will be described. Average the resistor 30 the current I = 200 flows [A], component around the solenoid coil 12 is assumed to undergo thermal damage at T _S = 5 [s]. In this case, when the resistor 30 is formed of a steel wire, the resistor 30 is melted when the temperature of the resistor 30 reaches the melting temperature θ _R = 1500 [° C.]. According to the equation (1), if the wire diameter of the steel wire constituting the resistor 30 is 3.1 [mm], the resistor 30 is melted down before the electromagnetic solenoid 11 becomes inoperable at the time of continuous energization, therefore It means that energization is cut off.

That is, even if the resistor 30 is energized for a long time, the material and disconnection of the resistor 30 are performed so that the solenoid 30 is melted and broken before the components around the solenoid coil 12 and the solenoid coil 12 are thermally damaged. The area is set. Even when the resistor 30 is melted and disconnected due to the long-time energization of the resistor 30, the electromagnetic switch 10 holds a circuit other than the resistor 30, and the first generated by the energization of the solenoid coil 12 from the battery 9 It is possible to bring the movable contact 21 into contact with the fixed

contacts

22a and 22b by means of a magnetic field of Therefore, since the current from the battery 9 flows to the motor 2 through the closed sub contact 20, it is possible to start the engine.

In the starter motor system 1 to which the electromagnetic switch 10 having the above configuration is connected, an operation of the motor 2 at the time of engine start will be described. When an engine start request is generated, the control device 8 energizes the magnet switch 3 and the main contact 7 is closed. By closing the main contact 7, the pinion 4 is pushed out and engaged with the ring gear 6, and energization of the motor 2 from the battery 9 via the resistor 30 is started. At this time, the current supplied to the motor 2 is limited by the resistor 30, and the motor 2 starts cranking of the engine while rotating at low speed.

After the motor 2 starts to rotate by closing the main contact 7 at time T1, the controller 8 starts energization of the solenoid coil 12 of the electromagnetic switch 10 by the battery 9 at time T2 after a predetermined timing has elapsed. The contact 20 is closed. When the sub contact 20 is closed, a circuit in which the resistor 30 is shorted is formed, so that the voltage of the battery 9 is fully applied to the motor 2, and the motor 2 starts cranking of the engine at high speed rotation. The time chart which showed the time change of the switching state of each of the main contact 7 and the sub contact 20 at this time, the voltage of the battery 9, and the electric current which flows into the motor 2 is FIG.

As shown in FIG. 4, the above-mentioned time T1 indicates the time when the main contact of the starter motor system 1 is closed, and the above-mentioned time T2 indicates the time when the sub contact 20 is closed. The voltage of the battery 9 at time T1 at the time of engine start due to the closing of the main contact of the starter motor system 1 remains at the voltage V1 by suppressing the current to the motor 2 by the resistor 30. That is, the current suppression to the motor 2 by the resistor 30 prevents the voltage drop of the battery 9 to a voltage lower than the voltage V1. Further, at time T2, the motor 2 is rotating at a low speed, and the voltage of the battery 9 remains at the voltage V2 by utilizing the counter electromotive voltage generated by the rotation of the motor 2. That is, the counter electromotive voltage generated by the rotation of the motor 2 prevents the voltage drop of the battery 9 to a voltage lower than the voltage V2. Therefore, it is possible to suppress the occurrence of a momentary power failure of the electrical component.

In FIG. 5, when a voltage is applied to the solenoid coil 12 of the electromagnetic switch 10 to operate the sub contact 20, a suction force that acts on the movable core 16 in a direction toward the fixed core 17 and the movable core 16 are The relationship with the spring reaction force which presses in the direction away from the fixed iron core 17 is shown. The spring reaction force for pressing the movable core 16 away from the fixed core 17 is the combined force of the contact pressure spring 24 and the return spring 25. The return spring 25 always applies a reaction force to the movable core 16. The contact pressure spring 24 starts to bend from the time when the movable contact 21 moving in synchronization with the movable core 16 contacts the fixed

contacts

22a and 22b. Therefore, the contact pressure spring 24 acts as a spring that generates a spring reaction force after the sub contact 20 is closed.

The suction force on the movable core 16 necessary for closing the sub contact 20 as the movable core 16 is driven and moved is inversely proportional to the amount of gap between the movable core 16 and the fixed core 17. Therefore, the strength of the first magnetic field and the second magnetic field necessary for closing the sub contact 20 as the movable iron core 16 is driven and moved varies with the position of the movable iron core 16. Is the largest when in the initial position.

Before the movable core 16 starts to move from the initial position, the current from the battery 9 to the motor 2 flows through the resistor 30, so that the largest movable magnetic core 16 is required. Between the start of movement and the closing of the sub contact 20, the second magnetic field generated by the current flowing through the resistor 30 can be used to generate an attractive force on the movable core 16. In the conventional electromagnetic switch, the movable core is driven only by the first magnetic field generated by the solenoid coil until the sub contact 20 is closed. In contrast to this, in the electromagnetic switch in the present embodiment, the first magnetic field that generates a suction force to the movable iron core 16 is required to be generated by the solenoid coil 12 until the sub contact 20 is closed. The voltage can be lowered. Therefore, the range of the battery voltage in which the sub contact 20 operates can be expanded to the low voltage side, and the reliability of the starter motor system 1 can be improved.

In the conventional electromagnetic solenoid, the sub contact is closed by the movable iron core being attracted toward the fixed iron core by the magnetic field generated when current flows through the solenoid coil. The suction force that drives the movable core is inversely proportional to the amount of gap between the movable core and the fixed core. Therefore, the strength of the magnetic field required to drive the movable iron in the initial state to close the sub contact is larger than the strength of the magnetic field required to maintain the sub contact in the closed state. The coil specifications of the electromagnetic solenoid depend on the magnitude of the magnetic field that the movable core can attract when the sub contact is open.

In order to operate the conventional electromagnetic solenoid at low voltage and improve the reliability of the electromagnetic switch, the resistance value of the solenoid coil is decreased to increase the current flowing through the solenoid coil, thereby increasing the magnetic field generated by the solenoid coil. It is possible to do. When the current flowing through the solenoid coil increases, the amount of heat generation increases, which causes problems such as an increase in cost for measures against heat generation and an increase in power consumption. Increasing the number of turns of the solenoid coil can also increase the magnetic field generated by the solenoid coil. When the number of turns of the solenoid coil is increased, the cost increase due to the increase in the amount of material used for the solenoid coil and the increase in size of the electromagnetic solenoid due to the increase in volume (weight increase) of the solenoid coil become problems.

In the conventional electromagnetic switch, the electromagnetic solenoid generates a magnetic field to open and close the sub contact while the voltage of the battery is lowered by the current flowing from the battery to the motor through the resistor. If the voltage drop of the battery when the motor is energized is large due to deterioration of the battery or the like, the magnetic field generated by the electromagnetic solenoid may be weakened to make it impossible to close the sub contact. In that case, if the state where the current flowing from the battery to the motor continues to be limited by the resistor continues, the start time of the engine becomes long.

In the state where the sub contact can not be closed due to the deterioration of the battery etc., if a large current for driving the motor flows to the resistor of the conventional electromagnetic switch for a long time, the resistor may be melted or In some cases, thermal damage may occur to components such as electromagnetic solenoids or bobbins. In such a case, there is a possibility that the conduction path from the battery to the motor is lost and the engine can not be started.

The electromagnetic switch 10 in the present embodiment includes a resistor 30, a sub contact 20, a solenoid coil 12, and a movable iron core 16. The resistor 30 suppresses the current flowing from the battery 9 to the motor 2 for starting the engine. Sub contact 20 includes fixed

contacts

22 a and 22 b and movable contact 21 arranged in parallel to resistor 30. The solenoid coil 12 generates a first magnetic field by energization from the battery 9. The movable core 16 is surrounded by the solenoid coil 12. The resistor 30 has a coil portion 31 and is disposed in the magnetic circuit 19 of the solenoid coil 12. The coil portion 31 of the resistor 30 surrounds the movable core 16 so as to generate a second magnetic field for bringing the movable contact 21 into contact with the fixed

contacts

22a and 22b in the same direction as the first magnetic field when current flows. It is formed into a coil shape.

The electromagnetic switch 10 according to the present embodiment having the above configuration allows the resistor 30 built in the electromagnetic switch 10 to start closing the sub contact 20 requiring the largest magnetic field because the electromagnetic solenoid 11 is at the initial position. The second magnetic field generated by the motor current flowing through the magnetic flux can be used as a suction force to the movable core 16. Since the first magnetic field that needs to be generated by the solenoid coil 12 can be small, the minimum operating voltage of the electromagnetic solenoid 11 can be lowered without an increase in weight or cost, and the reliability of the electromagnetic switch 11 at engine startup and Safety can be improved.

(Modification)
(1) The attractive force generated on the movable core 16 by the second magnetic field generated by the motor current flowing through the resistor 30 does not exceed the spring reaction force which is the combined force of the contact pressing spring 25 and the return spring 24. Preferably, the suction force is smaller than the suction force required for the sub contacts 20 to close by contacting the fixed

contacts

22a and 22b. That is, the sub contact 20 does not close immediately after the main contact 7 is closed at time T1 and current starts to flow in the resistor 30, but as shown in FIG. 4, the sub contact 20 is closed at time T2 after time T1. Close is preferred. The resistor 30 is set such that the control of the energization from the battery 9 to the solenoid coil 12 by the control device 8 is required for the sub contact 20 to close. Thus, the time from the time T1 at which the battery 9 starts energization to the starter motor system 1 to the time T2 at which the energization of the resistor 30 is short-circuited can be arbitrarily set without being affected by the specifications of the resistor 30 It becomes.

(2) FIG. 6 shows a modification of the resistor 30. The coil portion 31 included in the resistor 30 generates a suction force to the movable contact 16, and a single ring coil along with the

boundary portions

34 a and 34 b between the

end portions

32 a and 32 b of the resistor 30 and the coil portion 31. Molded into a shape. The single-ring annular shape of the coil portion 31 is less than 360 degrees by the thickness of each of the

tubular end portions

32 a and 32 b of the resistor 30. The resistor 30 is based on the electrical resistivity Ω [Ωm] of the resistor 30 determined by the material of the resistor 30, the total length L [m] of the resistor 30, and the cross-sectional area A [m ² ] of the resistor 30. The equation (2) is set to have the required resistance value R [Ω] of the resistor 30.
R = ρ × (L / A) (2)

For example, the required resistance value R of the resistor 30 is 10 mΩ, and the electrical resistivity = 1 = 15.4 × 10 ⁻⁷ Ωm when the resistor 30 is formed of a steel wire. Sometimes, the total length L [m] of the resistor 30 and the cross-sectional area A [m ² ] of the resistor 30 are determined by the equation (2). In this manner, the material and the cross-sectional area of the resistor 30 are set so that the required resistance value can be obtained in the resistor 30.

In the resistor 30 shown in FIG. 3, in order to connect both

end portions

32 a and 32 b of the resistor 30 and the sub contact 20, the end 32 b of the resistor 30 is a multiple of the coil portion 31 of the resistor 30. Of the annular ring, it protrudes outside the annular ring including the boundary 34 a between the end 32 a of the resistor 30 and the coil portion 31. That is, the ring including the boundary 34 b between the end 32 b of the resistor 30 and the coil portion 31 is different from the ring including the boundary 34 a. In the resistor 30 shown in FIG. 6, since the ring shape of the coil portion 31 of the resistor 30 is single, the coil portion 31 of the resistor 30 has one of the

end portions

32a and 32b of the resistor 30. There is no need to pass outside or inside the ring shape. Therefore, the outer diameter of the resistor 30 can be reduced, and as a result, the physical size of the electromagnetic switch 10 can be reduced.

The suction force acting on the movable core 16 is determined by the product nI of the number of turns n of the coil and the current I. For example, when the number n of turns of the solenoid coil 12 = 200 and the current I = 10 [A] supplied to the solenoid coil 12, the attraction force acting on the movable iron core 16 overcomes the spring reaction force of the return spring 25 and the movable iron core 16 Move toward the stationary core 17. That is, when the product nI = 2000 of the number of turns n = 200 of the solenoid coil 12 and the current I = 10 [A], the movable core 16 moves toward the fixed core 17. In the resistor 30, a large current I = 500 [A] necessary for driving the motor 2 flows. Since the product nI of the number of turns n = 1 of the resistor 30 and the current I = 500 [A] is nI = 500 even when the number of turns n of the resistor 30 is 1, the movable core 16 of the resistor 30 is It is possible to generate 25% of the product nI = 2000 of the number of coil turns n and the current I necessary to move towards the fixed core 17.

(3) FIG. 7 shows another modified example of the resistor 30. The coil portion 31 of the resistor 30 has a folded portion 33 and has two partial coils before and after the folded portion 33. The directions in which the two partial coils are wound respectively are opposite to each other, and the numbers of coil turns of the two partial coils are different. When a current flows through the coil portion 31 of the resistor 30 when the motor is energized, the strength of the magnetic field generated by each of the two partial coils is proportional to the number of turns of each of the two partial coils. Since the direction of the magnetic field generated by one of the two partial coils is exactly opposite to the direction of the magnetic field generated by the other of the two partial coils, the strength of the magnetic field generated by each of the two partial coils The two cancel each other. By changing the difference in the number of turns of the two partial coils, it is possible to adjust the strength of the second magnetic field without changing the resistance value.

The above-described embodiment and modifications may be combined with each other.

1: Start motor system 2: Motor 3: Magnet switch 4: Pinion 5: Shift lever 6: Ring gear 7: Main contact 8: Control device 9: Battery 10: Electromagnetic switch 11: Electromagnetic solenoid 12: Solenoid coil 13: Bobbin 14: External terminal 15: Earth circuit 16: Movable iron core 17: Fixed iron core 18: Coil case 19: Magnetic circuit 20: Sub contact 21: Movable contact 22: Fixed contact 23: Contact case 24: Contact pressing spring 25: Return spring 30: Resistance Body 31: Coil portion 32: End portion 33: Folded portion 34: Boundary portion

Claims

A resistor for suppressing the current flowing from the battery to a starter motor for starting the engine;
A sub contact including a fixed contact and a movable contact arranged in parallel to the resistor;
A solenoid coil that generates a first magnetic field by energization from the battery;
An electromagnetic switch comprising: a movable core surrounded by the solenoid coil;
The resistor is disposed in a magnetic circuit of the solenoid coil, and generates a second magnetic field for bringing the movable contact into contact with the fixed contact in the same direction as the first magnetic field when the current flows. An electromagnetic switch comprising: a coil portion formed in a coil shape surrounding the movable core.
In the electromagnetic switch according to claim 1,
An electromagnetic switch characterized in that a suction force generated on the movable core by the second magnetic field is smaller than a suction force required for the movable contact to contact the fixed contact.
In the electromagnetic switch according to claim 2,
The solenoid coil further includes an insulating layer formed of an insulating member and an air gap on the outer periphery of the solenoid coil,
The electromagnetic switch, wherein the resistor surrounds the solenoid coil through the insulating layer.
In the electromagnetic switch according to claim 3,
An electromagnetic switch characterized in that a material and a cross-sectional area of the resistor are set so that the solenoid coil and components around the solenoid coil are melted and disconnected before being thermally damaged when energized.
The electromagnetic switch according to any one of claims 1 to 4, wherein
The resistor includes the coil portion and an end portion,
An electromagnetic switch characterized in that the coil portion is formed into a single annular coil shape with a boundary portion between the end portion and the coil portion.
The electromagnetic switch according to any one of claims 1 to 4, wherein
The resistor has two partial coils,
The directions in which the two partial coils are respectively wound are opposite to each other,
An intensity of the second magnetic field is determined according to a difference in the number of turns of the two partial coils.