Solenoid device and solenoid system

Abstract

A solenoid device includes two electromagnetic coils, two stationary cores, two plungers and a yoke that surrounds the two electromagnetic coils. When a first electromagnetic coil is energized, magnetic flux flows through a first magnetic circuit that includes the first stationary core. When the two electromagnetic coils are energized, magnetic flux of the first electromagnetic coil flows through the first magnetic circuit, and magnetic flux of the second electromagnetic coil flows through a second magnetic circuit that includes a second stationary core. When energization of the first electromagnetic coil is stopped while maintaining energization of the second electromagnetic coil, the magnetic flux of the second electromagnetic coil continues to flow through the second magnetic circuit and a third magnetic circuit that includes the two stationary cores. A magnetism limiting portion is disposed in a portion of the second magnetic circuit that does not overlap the third magnetic circuit.

Claims

1. A solenoid device comprising: two electromagnetic coils that are configured by a first electromagnetic coil and a second electromagnetic coil, the first electromagnetic coil being energized to generate magnetic flux, the second electromagnetic coil being energized to generate magnetic flux; two stationary cores that are configured by a first stationary core and a second stationary core, the first stationary core being disposed within the first electromagnetic coil, the second stationary core being disposed within the second electromagnetic coil; two plungers that are configured by a first plunger and a second plunger, the first plunger being attracted to the first stationary core by energization of the first electromagnetic coil, the second plunger being attracted to the second stationary core by energization of the second electromagnetic coil; and a yoke that surrounds the two electromagnetic coils, wherein: in a dual-deenergized state in which neither of the two electromagnetic coils is energized, the first plunger is separated from the first stationary core and the second plunger is separated from the second stationary core; when the dual-deenergized state is changed to a state in which only the first electromagnetic coil of the two electromagnetic coils is energized, the magnetic flux of the first electromagnetic coil flows through a first magnetic circuit that includes only the first stationary core of the two stationary cores, and the first plunger is thereby attracted to the first stationary core while maintaining a state in which the second plunger is separated from the second stationary core; in a dual-energized state in which both of the two electromagnetic coils are energized, the magnetic flux of the first electromagnetic coil flows through the first magnetic circuit and the magnetic flux of the second electromagnetic coil flows through a second magnetic circuit that includes only the second stationary core of the two stationary cores, and as a result of a magnetic force that is thereby generated, the first plunger is attracted to the first stationary core, and the second plunger is attracted to the second stationary core, and the magnetic fluxes, respectively generated from the first electromagnetic coil and the second electromagnetic coil, flow through a third magnetic circuit that includes the two stationary cores; when, from the dual-energized state, energization of the first electromagnetic coil is stopped while maintaining energization of the second electromagnetic coil, the magnetic flux of the second electromagnetic coil continues to flow through the second magnetic circuit and the third magnetic circuit, and as a result of a magnetic force that is thereby generated, a dual-attracting state in which the first plunger is attracted to the first stationary core and the second plunger is attracted to the second stationary core is maintained; a magnetism limiting portion that limits magnetic flux is provided in only the second magnetic circuit, of the first magnetic circuit and the second magnetic circuit; and the magnetism limiting portion being disposed in a portion of the second magnetic circuit that does not overlap the third magnetic circuit.

2. The solenoid device according to claim 1, wherein: the magnetism limiting portion is a magnetically-saturated portion that is configured by a portion of the yoke and in which magnetism is at saturation.

3. The solenoid device according to claim 1, wherein: a slit that divides the yoke is formed in the yoke configuring the second magnetic circuit, and the slit configures the magnetism limiting portion.

4. A solenoid system comprising: a solenoid device including: two electromagnetic coils that are configured by a first electromagnetic coil and a second electromagnetic coil, the first electromagnetic coil being energized to generate magnetic flux, the second electromagnetic coil being energized to generate magnetic flux; two stationary cores that are configured by a first stationary core and a second stationary core, the first stationary core being disposed within the first electromagnetic coil, the second stationary core being disposed within the second electromagnetic coil: two plungers that are configured by a first plunger and a second plunger, the first plunger being attracted to the first stationary core by energization of the first electromagnetic coil, the second plunger being attracted to the second stationary core by energization of the second electromagnetic coil; and a yoke that surrounds the two electromagnetic coils; and a control unit that controls energization of the two electromagnetic coils, wherein: in a dual-deenergized state in which neither of the two electromagnetic coils is energized, the first plunger is separated from the first stationary core and the second plunger is separated from the second stationary core; when the dual-deenergized state is changed to a state in which only the first electromagnetic coil of the two electromagnetic coils is energized, the magnetic flux of the first electromagnetic coil flows through a first magnetic circuit that includes only the first stationary core of the two stationary cores, and the first plunger is thereby attracted to the first stationary core while maintaining a state in which the second plunger is separated from the second stationary core; in a dual-energized state in which both of the two electromagnetic coils are energized, the magnetic flux of the first electromagnetic coil flows through the first magnetic circuit and the magnetic flux of the second electromagnetic coil flows through a second magnetic circuit that includes only the second stationary core of the two stationary cores, and as a result of a magnetic force that is thereby generated, the first plunger is attracted to the first stationary core, and the second plunger is attracted to the second stationary core, and the magnetic fluxes, respectively generated from the first electromagnetic coil and the second electromagnetic coil, flow through a third magnetic circuit that includes the two stationary cores; when, from the dual-energized state, energization of the first electromagnetic coil is stopped while maintaining energization of the second electromagnetic coil, the magnetic flux of the second electromagnetic coil continues to flow through the second magnetic circuit and the third magnetic circuit, and as a result of a magnetic force that is thereby generated, a dual-attracting state in which the first plunger is attracted to the first stationary core and the second plunger is attracted to the second stationary core is maintained; a magnetism limiting portion that limits magnetic flux is provided in only the second magnetic circuit, of the first magnetic circuit and the second magnetic circuit; and the magnetism limiting portion being disposed in a portion of the second magnetic circuit that does not overlap the third magnetic circuit; and when the dual-energized state is entered by the control unit, orientation of a current flowing to each of the electromagnetic coils is prescribed such that the magnetic flux of the first electromagnetic coil and the magnetic flux of the second electromagnetic coil flow in a same direction in the third magnetic circuit.

5. The solenoid system according to claim 4, wherein: the control unit is configured to stop energization of the first electromagnetic coil after the dual-energized state, and allow the magnetic flux of the second electromagnetic coil to flow to the second magnetic circuit and the third magnetic circuit, thereby continuously maintaining the dual-attracting state.

6. The solenoid system according to claim 5, wherein: a portion of the magnetic flux of the second electromagnetic coil flows through a fourth magnetic circuit that includes only the second stationary core, of the two stationary cores, and the yoke, and partially overlaps the first magnetic circuit and the third magnetic circuit, and an auxiliary magnetism limiting portion that limits magnetic flux is formed in a portion of the yoke that configures the fourth magnetic circuit and does not overlap the first magnetic circuit and the third magnetic circuit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the accompanying drawings:

(2) FIG. 1 is a perspective view of a section of a solenoid device according to a first embodiment;

(3) FIG. 2 is a cross-sectional view of the solenoid device in a dual-deenergized state, according to the first embodiment;

(4) FIG. 3 is a cross-sectional view of the solenoid device in a case in which the dual-deenergized state is changed to a state in which only a first electromagnetic coil is energized, according to the first embodiment;

(5) FIG. 4 is a cross-sectional view of the solenoid device in a dual-energized state, according to the first embodiment;

(6) FIG. 5 is a cross-sectional view of the solenoid device in a state in which energization of the first electromagnetic coil is stopped after the dual-energized state;

(7) FIG. 6 is an enlarged cross-sectional view of a main section in FIG. 5;

(8) FIG. 7 is a cross-sectional view taken along VII-VII in FIG. 5;

(9) FIG. 8 is a circuit diagram of a solenoid system in the dual-deenergized state according to the first embodiment;

(10) FIG. 9 is a circuit diagram of the solenoid system in a state in which only a first switch is turned ON and a capacitor is pre-charged, according to the first embodiment;

(11) FIG. 10 is a circuit diagram of the solenoid system in a dual-attracting state after the state in FIG. 9;

(12) FIG. 11 is a circuit diagram of the solenoid system in a state in which a pre-charge relay is turned OFF and power is supplied to an electrical apparatus after FIG. 10;

(13) FIG. 12 is a cross-sectional view of a solenoid device according to a second embodiment;

(14) FIG. 13 is a perspective view of a second side wall portion of the solenoid device according to the second embodiment;

(15) FIG. 14 is a cross-sectional view of a solenoid device in a dual-deenergized state in a comparison example;

(16) FIG. 15 is a cross-sectional view of the solenoid device in a state in which only the first plunger is attracted, in the comparison example; and

(17) FIG. 16 is a cross-sectional view of the solenoid device in a dual-attracting state in the comparison example.

DESCRIPTION OF THE EMBODIMENTS

(18) Embodiments of solenoid device will hereinafter be described with reference to the drawings. In the following embodiments, a solenoid device can be used as an on-board solenoid device that is mounted in a vehicle, such as an electric car or a hybrid car.

First Embodiment

(19) A solenoid device and a solenoid system according to a first embodiment will be described with reference to FIGS. 1 to 11.

(20) As shown in FIGS. 1 and 2, the solenoid device 1 according the present embodiment includes two electromagnetic coils 2, two stationary cores 3, two plungers 4, and a yoke 5. The two electromagnetic coils 2 are configured by a first electromagnetic coil 2a and a second electromagnetic coil 2b that are arranged side by side in a predetermined direction (hereinafter referred to as an arrangement direction). The two stationary cores 3 are configured by a first stationary core 3a and a second stationary core 3b. The two plungers 4 are configured by a first plunger 4a and a second plunger 4b that are movable in a predetermined direction (hereinafter referred to a forward-backward direction).

(21) In the following drawings, three directions, i.e., X, Y, and Z directions orthogonal to one another, are shown for convenience of explanation. Z direction corresponds to the forward-backward direction of the respective plungers 4. X direction corresponds to the arrangement direction of the two electromagnetic coils 2. Y direction corresponds to a direction that is perpendicular to the arrangement direction of the two electromagnetic coils 2 and perpendicular to the forward-backward direction of the respective plungers 4.

(22) The first electromagnetic coil 2a is energized to generate magnetic flux. The second electromagnetic coil 2b is energized to generate magnetic flux. The first stationary core 3a is disposed within the first electromagnetic coil 2a. The second stationary core 3b is disposed within the second electromagnetic coil 2b. The first plunger 4a is attracted to the first stationary core 3a by energization of the first electromagnetic coil 2a. The second plunger 4b is attracted to the second stationary core 3b by energization of the second electromagnetic coil 2b. The yoke 5 surrounds the two electromagnetic coils 2, that is, the first electromagnetic coil 2a and the second electromagnetic coil 2b.

(23) As shown in FIG. 2, in a dual-deenergized state in which neither of the two electromagnetic coils 2 is energized, the first plunger 4a is separated from the first stationary core 3a. The second plunger 4b is separated from the second stationary core 3b.

(24) As shown in FIG. 3, when the dual-deenergized state is changed to a state in which only the first electromagnetic coil 2a, of the two electromagnetic coils 2, is energized, magnetic flux 1 of the first electromagnetic coil 2a flows through a first magnetic circuit C1. The first magnetic circuit C1 includes only the first stationary core 3a of the two stationary cores 3, that is, the first stationary core 3a and the second stationary core 3b. As a result, the first plunger 4a is attracted to the first stationary core 3a while a state in which the second plunger 4b is separated from the second stationary core 3b is maintained.

(25) As shown in FIG. 4, in a dual-energized state in which both of the two electromagnetic coils 2 are energized, the magnetic flux 1 of the first electromagnetic coil 2a flows through the first magnetic circuit C1. In addition, magnetic flux 2 of the second electromagnetic coil 2b flows through a second magnetic circuit C2. The second magnetic circuit C2 includes only the second stationary core 3b of the two stationary cores 3a and 3b. As a result of a magnetic force that is thereby generated, the first plunger 4a is attracted to the first stationary core 3a and the second plunger 4b is attracted to the second stationary core 3b. In addition, the magnetic fluxes 1 and 2 respectively generated from the two electromagnetic coils 2a and 2b flow through a third magnetic circuit C3. The third magnetic circuit C3 includes the two stationary cores 3a and 3b.

(26) As shown in FIG. 5, from the dual-energized state, when energization of the first electromagnetic coil 2a is stopped while maintaining energization of the second electromagnetic coil 2b, the magnetic flux 2 of the second electromagnetic coil 2b continues to flow through the second magnetic circuit C2 and the third magnetic circuit C3. As a result of the magnetic force thereby generated, a dual-attracting state in which the first plunger 4a is attracted to the first stationary core 3a and the second plunger 4b is attracted to the second stationary core 3b is maintained.

(27) A magnetism limiting portion 6 is formed in only the second magnetic circuit C2, of the first magnetic circuit C1 and the second magnetic circuit C2. The magnetism limiting portion 6 limits magnetic flux. In addition, the magnetism limiting portion 6 is formed in a portion of the second magnetic circuit C2 that does not overlap the third magnetic circuit C3.

(28) The solenoid device 1 of the present embodiment is an on-board solenoid device that is mounted in a vehicle, such as an electric car or a hybrid car. The solenoid device 1 is used in a relay 19. Two switches 7, that is, a first switch 7a and a second switch 7b, are disposed in the relay 19. The first switch 7a is turned ON and OFF by moving the first plunger 4a in the forward-backward direction (Z direction). The second switch 7b is turned ON and OFF by moving the second plunger 4b in the forward-backward direction (Z direction).

(29) As described above, the first magnetic circuit C1 is a magnetic circuit that includes only the first stationary core 3a, of the two stationary cores 3a and 3b. As shown in FIG. 3, as the magnetic circuits including only the first stationary core 3a, there is a magnetic circuit (first magnetic circuit C1) in which the magnetic flux 1 of the first electromagnetic coil 2a passes through a first side wall portion 54 and a magnetic circuit (fifth magnetic circuit C5) in which the magnetic flux 1 passes through a second side wall portion 55.

(30) The first side wall portion 54 configures the yoke 5 and is adjacent to the first electromagnetic coil 2a. The second side wall portion 55 configures the yoke 5 and is adjacent to the second electromagnetic coil 2b. However, the fifth magnetic circuit C5 has a long path length and a high magnetic resistance. Therefore, only a small amount of magnetic flux 1 flows through the fifth magnetic circuit C5. In the present specification, the first magnetic circuit C1 refers to the magnetic circuit that includes only the first stationary core 3a, of the two stationary cores 3a and 3b, and in which the magnetic flux 1 flows through the first side wall portion 54, or in other words, that has a relatively short path length.

(31) As described above, the second magnetic circuit C2 is a magnetic circuit that includes only the second stationary core 3b, of the two stationary cores 3a and 3b. As shown in FIG. 5, as the magnetic circuits including only the second stationary core 3b, there is a magnetic circuit (second magnetic circuit C2) in which the magnetic flux 2 of the second electromagnetic coil 2b passes through the second side wall portion 55 and a magnetic circuit (fourth magnetic circuit C4) in which the magnetic flux 2 passes through the first side wall portion 54. In the present specification, the second magnetic circuit C2 refers to the magnetic circuit that includes only the second stationary core 3b, of the two stationary cores 3a and 3b, and in which the magnetic flux 2 flows through the second side wall portion 55, or in other words, that has a relatively short path length.

(32) As shown in FIG. 8, the solenoid device 1 according to the present embodiment is provided on a pair of power lines 81 (81p and 81n) connecting a direct-current power supply 12 and an electrical apparatus 13. The power lines 81 are a positive-side power line 81p and a negative-side power line 81n. The positive-side power line 81p connects a positive electrode of the direct-current power supply 12 and the electrical apparatus 13. The negative-side power line 81n connects a negative electrode of the direct-current power supply 12 and the electrical apparatus 13. The first switch 7a is provided on the negative-side power line 81n. The second switch 7b is provided on the positive-side power line 81p.

(33) A serial connection body 17 is connected in parallel with the second switch 7b. In the serial connection body 17, a pre-charge relay 15 and a pre-charge resistor 16 are connected in series. A capacitor 14 for smoothing is connected in parallel to the electrical apparatus 13. The electrical apparatus 13 is a power converter that converts direct-current power supplied from the direct-current power supply 12 to alternating-current power. According to the present embodiment, the power converter converts the direct-current power from the direct-current power supply 12 to alternating-current power, and an alternating current motor (not shown) is driven. As a result, the vehicle is able to run.

(34) When the electrical apparatus 13 is operated, should the two switches 7a and 7b be simultaneously turned ON in a state in which the capacitor 14 is not charged, inrush current may flow and the switches 7a and 7b may become fused. Therefore, according to the present embodiment, before the electrical apparatus 13 is operated, the first switch 7a and the pre-charge relay 15 are turned ON while the second switch 7b is turned OFF, as shown in FIG. 9. A current I is gradually supplied to the capacitor 14 via the pre-charge resistor 16. As a result, the capacitor 14 is gradually charged, and the flow of inrush current is prevented.

(35) After charging of the capacitor 14 is completed, as shown in FIG. 10, the second switch 7b is turned ON. Next, as shown in FIG. 11, the pre-charge relay 15 is turned OFF. As a result, direct-current power is supplied to the electrical apparatus 12 in a state in which the two switches 7a and 7b are turned ON.

(36) To perform the above-described operation, the solenoid device 1 according to the present embodiment is configured such as to be capable of attracting only the first plunger 4a (turning ON only the first switch 7a), as well as attracting both of the two plungers 4a and 4b (turning ON the two switches 7a and 7b). In addition, the amount of time over which the two plungers 4a and 4b are attracted, that is, the amount of time over which both of the two switches 7a and 7b are turned ON and power is supplied to the electrical apparatus 13 is long. Therefore, as described hereafter, the solenoid device 1 is capable of attracting both of the two plungers 4a and 4b by merely energizing the second electromagnetic coil 2b. Power consumption is reduced.

(37) As shown in FIGS. 8 to 11, a control unit S is connected to the solenoid device 1 (relay 19) and the pre-charge relay 15. The control unit 8 controls energization of the two electromagnetic coils 2a and 2b. A solenoid system 10 is configured by the solenoid device 1 and the control unit 8.

(38) As shown in FIGS. 1 and 2, the yoke 5 includes a bottom wall portion 52, an upper wall portion 53, the first side wall portion 54, and the second side wall portion 55. The two electromagnetic coils 2a and 2b are placed on the bottom wall portion 52. In addition, the stationary cores 3a and 3b are connected to the bottom wall portion 52. Hole portions 59 (59a and 59b) into which the plungers 4a and 4b are fitted are formed in the upper wall portion 53. As described above, the first side wall portion 54 is formed in a position adjacent to the first electromagnetic coil 2a. The second side wall portion 54 is formed in a position adjacent to the second electromagnetic coil 2b. As shown in FIG. 1, a through hole 550 is formed in the second side wall portion 55. A portion of the second side wall portion 55 that is adjacent to the through hole 550 serves as the magnetism limiting portion 6.

(39) The magnetism limiting portion 6 according to the present embodiment is composed of a portion of the yoke 5. The magnetism limiting portion 6 is a magnetically-saturated portion 60 in which magnetism is at saturation.

(40) Magnetism is at saturation indicates a state in which a magnetically saturated region of the B-H curve is entered. The magnetically saturated region can be defined as a region in which the density of magnetic flux is 50% or more of the density of saturated magnetic flux. In addition, the density of saturated magnetic flux refers to the density of magnetic flux of a magnetic material in a state in which an external magnetic field is applied to the magnetic material until the intensity of magnetism thereof no longer increases.

(41) As shown in FIG. 1, according to the present embodiment, as a result of the through hole 550 being formed, a thin portion is formed in the second side wall portion 55 in a localized manner. This portion serves as the magnetically-saturated portion 60 (magnetism limiting portion 6). As a result of the magnetically-saturated portion 60 being formed such as to be thin in this way, magnetism more easily reaches saturation in the magnetically-saturated portion 60 that in other portions of the second magnetic circuit C2.

(42) As shown in FIG. 2, the switch 7 includes a fixed contact 71, a movable contact 72, a fixed contact supporting portion 73, and a movable contact supporting portion 74. A contact-side spring member 79 is interposed between an upper plate 111 of a case 11 and the movable contact support portion 74. The movable contact support portion 74 is pressed toward the plunger 4 side by the contact-side spring member 79.

(43) In addition, a bar-shaped portion 48 is provided in the plunger 4. A plunger-side spring member 49 is interposed between the plunger 4 and the electromagnetic coil 2. The plunger 4 is pressed toward the switch 7 side by the plunger-side spring member 49.

(44) As shown in FIG. 3, when the first electromagnetic coil 2a is energized, the magnetic flux 1 is generated and flows through the first magnetic circuit C1. The first magnetic circuit C1 is composed of the first stationary core 3a, the first plunger 4a, and the upper wall portion 53, the first side wall portion 54, and the bottom wall portion 52 of the yoke 5. When the magnetic flux 1 flows through the first magnetic circuit C1, a magnetic force is generated and the first plunger 4a is attracted to the first stationary core 3a. Thus, the movable contact supporting portion 74 is pressed by the pressing force of the contact-side spring member 79. As a result, the first switch 7a is turned ON.

(45) As described above, according to the present embodiment, the magnetism limiting portion 6 is formed in only the second magnetic circuit C2, of the first magnetic circuit C1 and the second magnetic circuit C2. That is, the magnetism limiting portion 6 is not formed in the first magnetic circuit C1. Therefore, the magnetic resistance in the first magnetic circuit C1 is low. In addition, in a state in which the second electromagnetic coil 2b is not energized, as shown in FIG. 3, the second plunger 4b is not attracted to the second stationary core 3b. A gap G is present between the upper wall portion 53 and the second plunger 4b. Therefore, the magnetic resistance in the third magnetic circuit C3 (see FIG. 4) that includes this gap G is high. As a result, only the first plunger 4a, of the two plungers 4a and 4b, is attracted to the stationary core 3.

(46) When each of the two electromagnetic coils 2a and 2b is energized, the magnetic flux 92 of the second electromagnetic coil 2b flows through the second magnetic circuit C2. The second magnetic circuit C2 is composed of the second stationary core 3b, the second plunger 4b, and the bottom wall portion 52, the second wall portion 55, and the upper wall portion 53 of the yoke 5. When the magnetic flux 2 flows through the second magnetic circuit C2, a magnetic force is generated and the second plunger 4b is attracted to the second stationary core 3b. As a result, the second switch 7b is turned ON.

(47) When the second plunger 4b is attracted to the second stationary core 3b, the gap G (see FIG. 3) between the upper wall portion 53 and the second plunger 4b becomes small. Therefore, the magnetic resistance in the third magnetic circuit C3 decreases. The respective magnetic fluxes 1 and 2 of the two electromagnetic coils 2a and 2b flow through the third magnetic circuit C3. According to the present embodiment, the orientation of the current flowing through each of the electromagnetic coils 2a and 2b is prescribed such that the magnetic flux 1 of the first electromagnetic coil 2a and the magnetic flux 2 of the second electromagnetic coil 2b flow in the same direction in the third magnetic circuit C3. Therefore, the magnetic fluxes 1 and 2 of the two electromagnetic coils 2a and 2b are strengthened in the third magnetic circuit C3. The magnetic force that attracts the two plungers 4a and 4b to the stationary cores 3 is further generated.

(48) As described above, according to the present embodiment, the magnetism limiting portion 6 is formed in the second magnetic circuit C2. Therefore, the magnetic flux 2 of the second electromagnetic coil 2b can be limited by the magnetism limiting portion 6 and excess magnetic flux 2 can be sent to the third magnetic circuit C3.

(49) After the two electromagnetic coils 2a and 2b are energized in this way, as shown in FIG. 5, energization of the first electromagnetic coil 2a is stopped while maintaining energization of the second electromagnetic coil 2b. As a result, the magnetic flux 1 of the first electromagnetic coil 2a dissipates, and the magnetic flux 2 of the second electromagnetic coil 2b continues to flow through the third magnetic circuit C3. Therefore, the two plungers 4a and 4b can be continuously attracted to the stationary cores 3. Consequently, the two switches 7a and 7b can be continuously turned ON. At this time, energization of the first electromagnetic coil 2a is stopped. Thus, the two plungers 4a and 4b can be continuously attracted to the stationary cores 3 while reducing power consumption of the solenoid device 1.

(50) As shown in FIG. 5, a portion of the magnetic flux 2 of the second electromagnetic coil 2b also flows through the fourth magnetic circuit C4. As shown in FIGS. 5 and 7, the fourth magnetic circuit C4 is composed of the second stationary core 3b, the second plunger 4b, and the bottom wall portion 52, the first side wall portion 54, and the upper wall portion 53 of the yoke 5. The fourth magnetic circuit C4 partially overlaps the first magnetic circuit C1 (see FIG. 3) and the third magnetic circuit C3. The fourth magnetic circuit C4 does not include the first stationary core 3a.

(51) Therefore, even when the magnetic flux 2 flows through the fourth magnetic circuit C4, the magnetic force that attracts the first plunger 4a to the first stationary core 3a is not generated. As shown in FIG. 7, according to the present embodiment, an auxiliary magnetism limiting portion 51 is formed in the fourth magnetic circuit C4. As a result, the magnetic resistance in the fourth magnetic circuit C4 is increased, and the amount of magnetic flux 2 flowing through the fourth magnetic circuit C4 is reduced. Consequently, the amount of magnetic flux 2 flowing through the second magnetic circuit C2 and the third magnetic circuit C3 is increased, and the magnetic force that attracts the two plungers 4a and 4b to the stationary cores 3 is strengthened.

(52) The auxiliary magnetism limiting portion 51 is formed in a position on the fourth magnetic circuit 4 that does not overlap the first magnetic circuit C1 and the third magnetic circuit C3. Should the auxiliary magnetism limiting portion 51 be formed in a position overlapping the first magnetic circuit C1, the magnetic resistance in the first magnetic circuit C1 increases. A sufficient flow of magnetic flux 1 to the first magnetic circuit C1 becomes difficult to achieve when only the first electromagnetic coil 2a is energized (see FIG. 3). Therefore, the attraction force on the first plunger 4 may decrease.

(53) In addition, should the auxiliary magnetism limiting portion 51 be formed in a position overlapping the third magnetic circuit C3, the magnetic resistance in the third magnetic circuit C3 increases. A sufficient magnetic force may not be generated when the magnetic flux 2 flows through the third magnetic circuit C3 (see FIG. 5) and the two plungers 4a and 4b are attracted to the stationary cores 3. For the foregoing reasons, according to the present embodiment, the auxiliary magnetism limiting portion 51 is formed in a position on the fourth magnetic circuit C4 that does not overlap the first magnetic circuit C1 and the third magnetic circuit C3.

(54) As shown in FIG. 7, the upper wall portion 53 includes a first portion 53a, a second portion 53b, and a third portion 53c. The first portion 53a configures the first magnetic circuit C1 (see FIG. 5). The second portion 53b configures the second magnetic circuit C2. The third portion 53c is interposed between the two plungers 4a and 4b. The auxiliary magnetism limiting portion 51 is formed in a section connecting the first portion 53a and the third portion 53c. As shown in FIGS. 6 and 7, a slight gap g is formed between the first plunger 4a and the upper wall portion 53. Magnetic resistance is high. Therefore, when the magnetic flux 2 flows from the first portion 53a to the third portion 53c, the magnetic flux 92 flows through the auxiliary magnetism limiting portion 51 without passing through the first plunger 4a.

(55) As shown in FIG. 7, the auxiliary magnetism limiting portion 51 is configured by a portion of the yoke 5. Magnetism is at saturation in the auxiliary magnetism limiting portion 51.

(56) As described above, according to the present embodiment, as shown in FIG. 5, the two switches 7a and 7b are turned ON, and power is supplied to the electrical apparatus 13 (see FIG. 8). To subsequently stop the power supply, energization of the second electromagnetic coil 2b is stopped as shown in FIG. 2. As a result, the magnetic flux 2 dissipates and the magnetic force that attracts the plungers 4a and 4b to the stationary cores 3 dissipates. Consequently, the plungers 4 are pressed toward the switch 7 side by the pressing force of the plunger-side spring members 49. Then, the bar-shaped portions 48 come into contact with the movable contact supporting portions 74 and the movable contacts 72 separate from the fixed contacts 71. Therefore, the switches 7a and 7b are turned OFF.

(57) Next, working effects according to the present embodiment will be described. According to the present embodiment, as shown in FIG. 3, the magnetism limiting portion 6 is formed in only the second magnetic circuit C2, of the first magnetic circuit C1 and the second magnetic circuit C2. That is, the magnetism limiting portion 6 is not formed in the first magnetic circuit C1.

(58) Therefore, the magnetic resistance in the first magnetic circuit C2 can be made low. Consequently, when only the first electromagnetic coil 2a is energized, most of the magnetic flux 1 of the first electromagnetic coil 2a flows to the first magnetic circuit C1. The magnetic flux 1 hardly flows to the other magnetic circuits such as the third magnetic circuit C3. As a result, energizing the second electromagnetic coil 2b and canceling the magnetic flux 1 of the first electromagnetic coil 2a flowing through the third magnetic circuit C3 by the magnetic flux 2 of the second electromagnetic coil 2b is no longer required. Consequently, stable attraction of only the first plunger 4a becomes possible.

(59) Conventionally, as shown in FIGS. 14 and 15, the magnetism limiting portion 6 is formed in the first magnetic circuit C1 and the magnetic resistance in the first magnetic circuit C1 is increased. As a result, as shown in FIG. 15, the magnetic flux 1 of the first electromagnetic coil 2a is sent not only through the first magnetic circuit C1, but also the third magnetic circuit C3 (shared magnetic circuit). When only the first plunger 4a is attracted, the two electromagnetic coils 2a and 2b are energized and the magnetic flux 1 of the first electromagnetic coil 2a flowing through the third magnetic circuit C3 is canceled by the magnetic flux 2 of the second electromagnetic coil 2b.

(60) As a result, the magnetic fluxes apparently do not flow through the third magnetic circuit C3, and only the first plunger 4a is attracted. In addition, when both of the two plungers 4a and 4b are attracted, as shown in FIG. 16, energization of the second electromagnetic coil 2b is stopped. As a result, the magnetic flux 2 of the second electromagnetic coil 2b dissipates and the magnetic flux 1 of the first electromagnetic coil 2a flows through the third magnetic circuit C3. Consequently, both of the two plungers 4a and 4b are attracted to the stationary cores 3.

(61) However, in the above-described configuration, as shown in FIG. 15, when only the first plunger 4a is attracted, the amount of magnetic flux 1 of the first electromagnetic coil 2a and the amount of magnetic flux 2 of the second electromagnetic coil 2b flowing through the third magnetic circuit C3 are required to be substantially equal. When the amounts of the magnetic fluxes 1 and 2 significantly differ, cancellation of the magnetic fluxes 1 and 2 cannot be completely performed, and the magnetic fluxes 1 and 2 flow through the third magnetic circuit C3. Consequently, both of the two plungers 4a and 4b may be attracted. In particular, when a temperature difference occurs between the two electromagnetic coils 2a and 2b, the magnetic fluxes 1 and 2 become unbalanced. Attraction of both of the two plungers 4a and 4b tends to occur.

(62) For example, when the current is temporarily stopped after the two plungers 4a and 4b are attracted through energization of the first electromagnetic coil 2a (see FIG. 16), and subsequently, only the first plunger 4a is again attracted, the temperature of the first electromagnetic coil 2a is increased as a result of the immediately preceding operation. However, the temperature of the second electromagnetic coil 2b has relatively decreased. When the temperature increases, electrical resistance in the electromagnetic coil 2 increases, and the amount of flowing current decreases. Therefore, when the temperatures of the electromagnetic coils 2a and 2b differ from each other, the magnetic fluxes 1 and 2 tend to become unbalanced.

(63) Consequently, as shown in FIG. 15, when only the first plunger 4a is attracted, the magnetic fluxes 1 and 2 are not sufficiently canceled in the third magnetic circuit. Both of the two plungers 4a and 4b may be attracted. In addition, when the magnetic fluxes 1 and 2 are canceled and only the first plunger 4a is attracted, the magnetic flux 1 for attracting the first plunger 4a and the magnetic flux 2 for canceling the magnetic flux 1 are required to be sent to the first stationary core 3a. The necessity for thickening the first stationary core 3a tends to arise.

(64) Meanwhile, as shown in FIG. 3, when the magnetism limiting portion 6 is not formed in the first magnetic circuit C1 according to the present embodiment, the magnetic resistance in the first magnetic circuit C1 can be reduced. Most of the magnetic flux 1 of the first electromagnetic coil 2a can be sent to only the first magnetic circuit C1. Therefore, the magnetic flux 1 hardly flows through the third magnetic circuit C3. Cancellation of the magnetic flux 1 of the first electromagnetic coil 2a flowing through the third magnetic circuit C3 by the magnetic flux 2 of the second electromagnetic coil 2b, which is conventionally required, is no longer required. Consequently, stable attraction of only the first plunger 4a becomes possible.

(65) According to the present embodiment, as shown in FIG. 5, the magnetism limiting portion 6 is formed in the second magnetic circuit C2. Therefore, the magnetic resistance in the second magnetic circuit C2 can be increased. As a result, as shown in FIG. 4, when the two, electromagnetic coils 2a and 2b are energized, the magnetic flux 2 of the second electromagnetic coil 2b can also be sent to the third magnetic circuit C3. Consequently, both of the two plungers 4a and 4b can be attracted through energization of the two electromagnetic coils 2a and 2b. Subsequently, as shown in FIG. 5, when energization of the first electromagnetic coil 2a is stopped, both of the two plungers 4a and 4b can be continuously attracted because the magnetic flux 2 of the second electromagnetic coil 2b continues to flow through the third magnetic circuit C3. As a result, the two plungers 4a and 4b can be continuously attracted in a state in which only the second electromagnetic coil 2b is energized, that is, a state in which power consumption is reduced.

(66) As shown in FIG. 5, according to the present embodiment, the magnetism limiting portion 6 is formed in a portion of the second magnetic circuit C2 that does not overlap the third magnetic circuit C3.

(67) The magnetism limiting portion 6 can be formed in a portion of the second magnetic circuit C2 that overlaps the third magnetic circuit C3, such as the second stationary core 3b. However, in this case, the magnetic resistance in the third magnetic circuit C3 may increase. As a result, the magnetic flux 2 of the second electromagnetic coil 2b may not sufficiently flow through the third magnetic circuit C3 when the dual-energized state is maintained through energization of only the second electromagnetic coil 2b. Meanwhile, as according to the present embodiment, when the magnetism limiting portion 6 is formed in a portion of the second magnetic circuit C2 that does not overlap the third magnetic circuit C3, increase in the magnetic resistance in the third magnetic circuit C3 can be suppressed. Consequently, as shown in FIG. 5, the magnetic flux 2 of the second electromagnetic coil 2b can be sufficiently sent to the third magnetic circuit C3. Attraction force on the two plungers 4a and 4b can be increased.

(68) The magnetism limiting portion 6 of the present embodiment is the magnetically-saturated portion 60 in which magnetism is at saturation. The magnetically-saturated portion 60 is configured by a portion of the yoke 5 configuring the second magnetic circuit C2.

(69) As described hereafter, a slit 61 (see FIGS. 12 and 13) may be formed in the yoke 5. The slit 61 may serve as the magnetism limiting portion 6. In this case, adjustment of the amount of flowing magnetic flux becomes difficult. In the present embodiment, a portion of the yoke 5 serves as the magnetically-saturated portion 60 and the magnetically-saturated portion 60 serves as the magnetism limiting portion 6. Thus, the amount of flowing magnetic flux can be more easily adjusted.

(70) In addition, the solenoid system 10 according to the present embodiment includes the control unit 8 that controls energization of the electromagnetic coils 2. As shown in FIG. 4, when both of the two electromagnetic coils 2a and 2b are energized, the orientation of the current flowing through each of the electromagnetic coils 2a and 2b is prescribed such that the magnetic flux 1 of the first electromagnetic coil 2a and the magnetic flux 2 of the second electromagnetic coil 2b flow in the same direction in the third magnetic circuit C3.

(71) Therefore, the magnetic fluxes 1 and 2 flowing through the third magnetic circuit C3 can reinforce each other. Consequently, a strong magnetic force can be generated by the magnetic fluxes 1 and 2 flowing through the third magnetic circuit C3. The two plungers 4a and 4b can be firmly attracted.

(72) As shown in FIGS. 4 and 5, the control unit 8 stops energization of the first electromagnetic coil 2a after energizing both of the two electromagnetic coils 2a and 2b. As a result, the magnetic flux 2 of the second electromagnetic coil 2b flows through the second magnetic circuit C2 and the third magnetic circuit C2, and both of the plungers 4a and 4b can be continuously attracted. Therefore, the two plungers 4a and 4b can be continuously attracted merely through energization of the second electromagnetic coil C3. Power consumption of the solenoid device 1 can be reduced.

(73) As shown in FIGS. 5 and 7, a portion of the magnetic flux 2 of the second electromagnetic coil 2b flows through the fourth magnetic circuit C4. The auxiliary magnetism limiting portion 51 is formed in a portion of the yoke 5 that configures the fourth magnetic circuit C4, but does not configure the first magnetic circuit C1 and the third magnetic circuit C3. Therefore, the amount of magnetic flux 2 of the second electromagnetic coil 2b flowing through the fourth magnetic circuit C4 can be reduced. Consequently, the amount of magnetic flux 2 flowing through the second magnetic circuit C2 and the third magnetic circuit C3 can be increased. Attraction force on the plungers 4a and 4b can be increased.

(74) As described above, according to the present embodiment, a solenoid device that is capable of stably attracting only either of two plungers, and reducing power consumption when attracting both of the two plungers, and a solenoid system in which the solenoid device is used can be provided.

(75) According to an embodiment described below, reference numbers used in the drawings that are the same as those used according to the first embodiment indicate constituent elements similar to those according to the first embodiment, unless otherwise noted.

Second Embodiment

(76) According to a second embodiment, the shape of the second side wall portion 55 is modified. As shown in FIGS. 12 and 13, according to the present embodiment, a slit 61 is formed in the portion (second side wall portion 55) of the yoke 5 configuring the second magnetic circuit C2. The slit 61 divides the yoke 5 into two. More specifically, according to the present embodiment, the slit 61 divides the second side wall portion 55 of the yoke 5 into two, in the forward-backward direction (Z direction) of the plungers 4. The slit 61 configures the magnetism limiting portion 6.

(77) Working effects according to the present embodiment will be described. As described above, according to the present embodiment, the slit 61 is formed in the portion (second side wall portion 55) of the yoke 5 configuring the second magnetic circuit C2. Therefore, the amount of magnetic flux 2 flowing to the second magnetic circuit C2 can be further limited. Consequently, the amount of magnetic flux 2 flowing to the third magnetic circuit C3 can be increased. The first plunger 4a can be firmly attracted in the dual-attracting state. In addition, configurations and working effects similar to those according to the first embodiment are achieved.