Remotely controlled relay

Abstract: A remotely controlled relay having two micro-switches driven to open and close by the plunger of a bistable polar electromagnet device. A current is supplied to the coil of the electromagnet device from an external power source to magnetize the plunger so that the plunger is moved through a stroke between a first position and a second position. When the plunger moves from the first position to the second position, a first micro-switch is closed to energize the coil in a first direction until the plunger passes through the middle of the stroke. When the plunger moves from the second position to the first position, a second micro-switch is closed to energize the coil in a second direction until the plunger passes through the middle of the stroke.

Description: BACKGROUND OF THE INVENTION The present invention relates to a remotely-controlled relay according to the preamble of claim 1. Fig. 11 shows a remotely-controlled relay described in the same inventor's copending U.S. and European Patent Applications (published as US-A-5 200 723 and EP-A-0 458 301) based on Japanese Patent Application No.2-133027 (published as JP-A-4 028 135) which has the same filing date in Japan as that of the present invention. Consequently, these documents do not form prior art according to Article 54(2), (3) EPC. Fig. 14 shows the electrical circuit of the remotely controlled relay shown in Fig. 11. A relay having a very similar electrical circuit is known from EP 0 186 393 A3 which document discloses the features of the preamble of claim 1. Fig. 12 shows the relevant portion of the remotely controlled relay when a main circuit is open. When an operating switch is switched to the position B shown in Fig. 14, an operating current flows through a diode D2 and a coil 6 to drive a plunger 5 in the direction of the arrow A in Fig. 12. At this time, an operating lever 28 rotates clockwise. When the plunger 5 reaches the middle of its stroke, the operating lever 28 drives at its abutment 28c the actuator 26a of a micro-switch 26 so that the micro-switch 26 is switched to have a movable contact thereof in contact with 26d. The plunger 5 further advances upwards with the aid of inertia until it is securely attracted by the upper end of a yoke 8, causing the contacts 11 and 21 of the main circuit to close. Fig. 13 shows a relevant portion of a remotely controlled relay when a main circuit is closed. When an operating switch is switched to the position A in Fig. 14, the operating current flows through a diode D1 into the coil 6 to drive the plunger 5 in the direction of the arrow E in Fig. 13. At this time, the operating lever 28 rotates counterclockwise. When the plunger 5 reaches the middle of its stroke, the operating lever 28 drives at the abutment 28c the actuator 26a so that the micro-switch 26 is switched to have a movable contact thereof in contact with 26c. The plunger 5 further advances upward with the aid of inertia until it is securely attracted by the bottom of the yoke 8, causing the contacts 11 and 21 of the main circuit to open. In general, this type of bistable polar electromagnet device has a micro-switch that is switched at the middle of the plunger stroke. Thus, the attracting force of magnetized yoke 8 that attracts the plunger becomes increasingly stronger as the plunger becomes closer to the upper end or bottom of the yoke 8. This requires precise adjustment of the position of the micro-switch relative to the position of the plunger in its stroke where the micro-switch is switched from one contact to another. Thus, the manufacture of the relay is not easy. For sure operation of the micro-switch, a high current is run through the coil 6 so that the plunger 5 is driven by a large magnetic force to pass through the middle of the stroke with a large inertia. It is the object of the invention to provide a remotely-controlled relay that requires no critical, precise adjustment of the position of micro-switch relative to that of the plunger in its stroke. Another object of the invention is to provide a remotely controlled relay that requires only a small current for magnetizing the relay coil to drive the plunger. These objects, according to the present invention, are solved by the advantageous measures indicated in the characterizing part of claim 1. BRIEF DESCRIPTION OF THE DRAWINGS Features and other objects of the invention will be more apparent from the description of the preferred embodiments with reference to the accompanying drawings in which: Fig. 1 is a side view of a remotely controlled relay according to the invention when the main circuit is open; Fig. 2 is a side view showing the relevant portion of Fig. 1; Fig. 3 is a top view of Fig. 2; Fig. 4 shows an electrical circuit of the remotely controlled relay in Fig. 1; Fig. 5 is the electrical circuit of Fig. 6; Fig. 6 shows a plunger at the middle of its stroke; Fig. 7 is a side view of Fig. 1 showing the remotely controlled relay according to the invention when the main circuit is closed; Fig. 8 is a top view of Fig. 7; Fig. 9 shows the electrical circuit of the remotely controlled relay according to the invention when the main circuit is closed; Fig. 10 illustrates the relationship between the movement of plunger and the timing at which the micro-switch is switched; Fig. 11 shows a remotely controlled relay described in Japanese Patent Application No.2-133027; Fig. 12 shows the relevant portion of the remotely controlled relay in Fig. 11; Fig. 13 shows the relevant portion of Fig. 11 when the main circuit is closed; and Fig. 14 shows an electrical circuit of the remotely controlled relay in Fig. 11. DETAILED DESCRIPTION OF THE EMBODIMENTS EMBODIMENT An embodiment of the present invention will now be described in detail with reference to the drawings. Fig. 1 is a general side view of a remotely-controlled relay according to the invention. Fig. 2 is a side view of a relevant portion of Fig. 1. Fig. 3 is a top view of Fig. 2 and Fig. 4 is a side view of a relevant portion of Fig. 1. A housing consists of a base 1 and a cover 2 which are riveted together at four locations by rivets 3. The housing has grooves 1a into which mounting angles are inserted, projections by which the relay is mounted on DIN rails, and an aperture 1c at the top of the housing. An electromagnet device 4 is of a bistable polar type having two stable positions where a plunger 5 is securely attracted by a magnet, and is provided in the middle of the base 1. As shown in Figs. 1 and 2, a coil 6 is wound about a bobbin 7, shown hatched, through which the plunger 5 slidably extends. The plunger 5 acts as an armature having a top end 5b and a bottom end 5b, attracted by a yoke 8 magnetized by a permanent magnet 9. The bobbin 7 and the plunger 5 are housed in a first yoke 8, and the plunger 5 extends at a distal end thereof outwardly of the yoke 8 through an aperture 8a. On the inner wall of the first yoke 8 is provided a pair of permanent magnets 9. A second yoke 10 having a generally U-shaped cross section is mounted between the permanent magnet 9 and bobbin 7 such that the yoke 10 abuts the magnet 9 as well as holds the bobbin 7. A link 12 is pivotally mounted on the base 1 by means of a pin 13, and is pivotally connected at one end 12a thereof through a pin 14 to the plunger tip end 5c and at the other end 12b to one end of a movable-contact assembly 15 through a pin 16. The movable-contact assembly 15 is provided with an insulator 17 having a groove 17a into which a movable piece 18 engages in sliding relation. The movable piece 18 has a contact 11 which is electrically connected with a terminal 23 of the main circuit by means of a shunt 22. The contact 11 is provided with a compression spring 19 that urges the contact 11 against a fixed contact 21 on a terminal 20 of the main circuit. The movable-contact assembly 15 and the contacts 11 and 21 forms a main-circuit-opening and closing assembly. A pin 17b mounted to the insulator 17 loosely engages and guided by a groove(not shown) in the base 1 and a groove(not shown) in the cover 2 so that the movable-contact assembly 15 is operatively driven by the plunger 5 to close and open the contacts 11 and 14. The operating lever 28 is pivotally mounted to the base 1 by means of a pin 29 and is pivotally connected to the tip end 5c by means of a pin 14. The operating lever 28 pivots about the pin 29 when the plunger moves up and down. The operating lever 28 has a handle 28a facing the aperture 1c for manually operating the lever 28. On both sides of the handle 28a is provided a display 28c that indicates ON and OFF states of the contacts 11 and 14. Micro-switches 30 and 31 each have two holes therein through which pins 32 and 33 extends. The pins 32 and 33 are supported by the base 1 and cover 2. Thus, the two micro-switches are properly aligned their relative positions by the aid of the pins 32 and 33. To the pin 33 is pivotally connected an actuating lever 34 driven into pivotal motion by a projection 28d of the operating lever 28, which engages the bifurcation 34a of the actuating lever 34. When the operating lever 28 rotates about the pin 29, a projection 34b engages the actuator 31a of the micro-switch 31 to open and close the switch 31 while the abutment 28c engaging the actuator 30a of the micro-switch 30. Fig. 4 shows an electrical circuit of the remotely-controlled relay in Fig. 1. One end 6a of the coil 6 is connected to a control terminal 24b and the other 6b to the common terminals of the micro-switches 30 and 31. The contact of the micro-switch 30 is connected with the cathode of a diode D2, and the contact of the micro-switch SW31 to the anode of a diode D1. The cathode of D1 and the anode of D2 are connected together to a control terminals 24a. Between the terminals 24a and 24b is connected an external series connection of a power source and an operating switch 40 that includes diodes D3 and D4 and a normally open single-pole-double-throw switch 40a. Operation OFF-to-ON Operation Fig. 10 illustrates the relationship between the movement of plunger and the timing at which the micro-switch is switched. As shown in Fig. 2, the bottom end 5a is at the bottom of the yoke 8, securely attracted by the yoke 8. When the switch 40a is switched to the position J, an ON-operating current flows in the direction of the arrow C2 through the loop of D3 -- contact J -- coil 6 -- SW 31 -- D1 -- power source. The coil 6 magnetizes the plunger 5 in a direction opposite to the magnetic poles shown in Fig. 2, so that the plunger 5 repels the S pole of the bottom of yoke 8 and is driven in the direction of A in Fig. 2 to move to a point P in Fig. 10, causing the link 12 to rotate in the direction of B and operating lever 28 in the direction of C. At this time, the operating lever 28 engages at 28c the actuator 30 to drive the micro-switch 30 into the closed position while also causing the actuating lever 34 to rotate in the direction of D. Both the micro-switches SW30 and SW31 are closed during the time when the plunger travels from point P to point Q in Fig. 10. Fig. 6 shows the positional relationship between the relevant mechanical parts and Fig. 5 shows the electrical circuit of Fig. 6. It should be noted that the micro-switches 30 and 31 are both closed. In Fig. 6, the plunger 5 is advancing in the direction A. Although the micro-switches 30 and 31 are both closed while the plunger 5 is between points P and Q, no current flows through the micro-switch 30. The operating current continues to flow in the direction of C2 through the micro-switch 31 so as to drive the plunger 5 in the direction of A. Thus, the plunger 5 remains driven until it reaches point Q past the middle point M of the plunger stroke. When the plunger 5 arrives at point Q, the actuating lever 34 acts on the actuator 31a to open the micro-switch 31. At this time, the operating-current path changes from the loop of D3 -- contact J -- coil 6 -- SW31 -- D1 -- power source to the loop of D3 -- contact J -- coil 6 -- SW30 -- D2 -- power source, so that even if the operator continues to depress the switch 40a to side J, no current flows in the coil 6. Thus, the coil 6 no longer produces a force to drive the plunger 5. The plunger 5 is now sufficiently close to the upper end of yoke 8 to be attracted towards the upper end and stops at the position shown in Fig. 7 closing the contacts 11 and 14. ON-to-OFF Operation Fig. 7 is a side view showing a remotely-controlled relay when the main circuit is closed. Fig. 8 is a top view of Fig. 7. As shown in Fig. 7, the top end 5b is at the upper end of the yoke 8, securely attracted by the yoke 8. In Fig. 9, when the switch 40a is switched to the position K, an OFF-operating current flows in the direction of the arrow C1 through the loop of D2 -- SW30 -- coil 6 -- contact K -- D4 -- power source. The coil 6 magnetizes the plunger 5 to polarities opposite to those shown in Fig. 2, so that the plunger 5 repels the S pole of the upper end of yoke 8 and is driven in the direction of E to move to a point Q in Fig. 10, causing the link 12 to rotate in a direction of F and operating lever 28 in the direction of G. At this time, the operating lever 28 causes the actuating lever 34 to rotate in the direction of H. Both the micro-switches 30 and 31 are closed during the time when the plunger 5 travels from point P to point Q in Fig. 10. Fig. 6 shows the positional relationship between the relevant mechanical parts and Fig. 5 shows the electrical circuit of Fig. 6. It should be noted that the micro-switches 30 and 31 are both closed. In Fig. 6, the plunger is advancing in the direction of E. Although the micro-switches are both closed while the plunger 5 is between points P and Q, no current flows through the micro-switch 31. The operating current continues to flow in the direction of C1 through the micro-switch 30 so as to drive the plunger in the direction of E. Thus, the plunger 5 remains driven until it reaches point P past the middle point M of the plunger stroke. When the plunger 5 arrives at point P, the actuating lever 34 acts on the actuator 30a to open the micro-switch 30. At this time, the operating-current path changes from the loop of D2 --SW30 -- coil 6 -- contact K -- D4 -- power source to a loop of D1 -- SW31 coil 6 -- contact K -- D4 -- power source, so that even if the operator continues to depress the switch 40a to the side K, no current flows in the coil 6. Thus, the coil 6 no longer produces a force to drive the plunger 5. Since the plunger is now sufficiently close to the bottom of yoke 8, the plunger is attracted towards the bottom and then stops at the position shown in Fig. 7 opening the contacts 11 and 14.

Claims: Remotely-controlled relay, comprising: [a] a bistable polar electromagnetic device (4) for driving an opening and closing assembly (15) of a main circuit, said device (4) comprising: [a1] a coil (6) which is selectively energized in a first and in a second direction depending on the direction of a current supplied from an external circuit (40); and [a2] a plunger (5) having a stroke which allows a movement between a first and a second position, the respective direction of said stroke depending on the direction of the supplied current; and [b] a micro-switch means (SW30, SW31) which is arranged between said external circuit (40) and said coil (6) and which is operatively driven by said plunger (5) in such a way that the current supplied to said coil (6) is interrupted at a predetermined position of the stroke of said plunger (5); characterized in that [b1] said micro-switch means is comprised of two separate micro-switches (SW30, SW31) which are connected in parallel; [b2] wherein said two micro-switches (SW30, SW31) are operated by said plunger (5) such that one micro-switch (SW30) is being closed while the other micro-switch (SW31) is being opened, and vice-versa, and that both micro-switches (SW30, SW31) are closed in a middle region of the stroke of said plunger (5). Remotely-controlled relay according to claim 1, characterized in that each of said two micro-switches (SW30, SW31) is connected in series with a diode (D1, D2), the polarity of the diode (D1) of the one micro-switch (SW30) being opposite to the polarity of the diode (D2) of the other micro-switch (SW31). Remotely-controlled relay according to claim 1 or 2, characterized in that one micro-switch (SW30) is operated by an operating lever actuated by said plunger (5) and the other micro-switch (SW31) is operated by an actuating lever driven by said operating lever.

Inventors: FUJIHISA HIROAKI, SOGABE MANABU, FUJIHISA, HIROAKI, SOGABE, MANABU, Fujihisa, Hiroaki, c/o Mitsubishi Denki K.K., Sogabe, Manabu, c/o Mitsubishi Denki K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1991
Main classification: H01H51
IPC codes: H01H51, H01H47, H01H50