MOVEABLE CONTACT PIECE, AND ELECTROMAGNETIC RELAY PROVIDED WITH SAME

Abstract

 Provided is a movable plate 60 which needs less energy consumption, less components, and less assembling processes, but ensures a high productivity. The movable contact plate, comprising three stacked conductive thin plate springs 61, 65, 67, has one end connected to a movable contact terminal 54 and the other end supporting movable contacts 56, 57 integrally fixed thereto. The plate is drivingly moved in its thicknesswise direction by an engagement at a distal end thereof with a card 40 to make and break contacts with stationary contacts 52, 53. The inward conductive thin plate spring has at its distal end a driving elastic tongue 64a and the outward conductive thin plate spring has at its distal end a pair of returning elastic tongues 67b, 67c which are configured to take a condition that only one of the returning elastic tongues makes a contact with the card while the movable contact plate is being moved toward a condition where the movable and stationary contacts are disconnected.

Description

TECHNICAL FIELD

[0001] The present invention relates to a movable contact plate and, more particularly, to a movable contact plate having at least two, stacked conductive plate springs.

BACKGROUND

[0002] Conventionally, there has been disclosed a movable contact plate in Patent Document 1. The movable contact plate 4 is made of, for example, three stacked conductive plate springs 3 with one ends thereof fixed to a first relay terminal 2 and the other distal ends thereof supporting a contact button 6 fixed thereto.

[0003] Patent Document 1: US Patent No. 6,661,319

[0004] According to this movable contact plate, the elastic contact plate 14 is pulled up by only actuator 13, which needs a considerably separation force and, as a result, a considerable energy consumption for breaking a contact fusing between the movable and stationary contacts 6 and 3 which may cause at the connection of those contacts.

[0005] Also, as shown in Figs. 3-5, an additional elastic member 16 should be mounted on the distal end 5 of the elastic contacts plates 4, which eventually increases the number of components and assembling processes and decreases the productivity of the movable contact plate.

[0006] To overcome the problems, an object of the invention is to provide an improved movable contact plate which requires less energy consumption, less components, and less assembling processes but ensures a high productivity of the movable contact plate.

SUMMARY OF THE INVENTION

[0007] Accordingly, a movable contact plate according to the invention comprises at least two, stacked conductive thin plate springs, the movable contact plate having one end connected to a movable contact terminal and the other end supporting a movable contact integrally fixed thereto, the movable contact plate being drivingly moved in a thicknesswise direction thereof by an engagement at a distal end thereof with a card to make and break contact with a stationary contact, wherein one of the conductive thin plate springs has at a distal end thereof a driving elastic tongue and the other of the conductive thin plate springs has at a distal end thereof a pair of returning elastic tongues, the pair of returning elastic tongues being configured to take a condition that only one of the returning elastic tongues makes a contact with the card while the movable contact plate is being moved toward a condition where the movable and stationary contacts are disconnected.

[0008] According to the invention, because only one of the paired returning elastic tongues is configured to make contact with the distal end of the conductive thin plate spring to cause not only a separation force but also a torsional force in the movable contact plate in the process of contact breaking, the movable contact is easy to be disconnected from the stationary contact even if the existence of the contact fusing, with less energy consumption.

[0009] Also, the driving and returning elastic tongues are formed in the distal ends of different conductive thin plate springs, which reduces the number of components and assembling processes and provides a high productivity for the production of the contact plates.

[0010] In another aspect of the invention, the movable contact plate may have three conductive thin plate springs, one of three conductive thin plate springs including an intermediate conductive thin plate spring positioned between another two conductive thin plate springs, the intermediate conductive thin plate spring having at a distal end thereof a position regulating elastic tongue which is configured to engage and regulate opposite sides of the card.

[0011] According to this aspect of the invention, the position regulating elastic tongue prevents an unstable movement of the movable plate in its widthwise direction, which ensures a stable operating characteristic of the movable plate

[0012] In another aspect of the invention, at least one of the conductive thin plate springs has a spring constant adjusting slit.

[0013] According to this aspect of the invention, the movable plates with an enhanced design flexibility and capable of accommodating customer needs can be provided.

[0014] In another aspect of the invention, the conductive thin plate springs have folds defined at mid-portions thereof, the folds being configured to have different sizes so that they are arranged one on top the other.

[0015] According to this aspect of the invention, in spite the fact that the conductive thin plate springs are connected to each other, the folks accommodate and ease strains caused at the elastic deformations, which ensures a stable performance of the movable plate.

[0016] In another aspect of the invention, the stacked conductive thin plate springs support a pair of movable contacts spaced apart from each other in a widthwise direction of the movable contact plate.

[0017] According to this aspect of the invention, the twin contact structure ensures an enhanced contact reliability of the movable plate.

[0018] To overcome the problems, an electromagnetic relay according to the invention comprises any one of the contact mechanisms described above.

[0019] According to the invention, because only one of the paired returning elastic tongues is configured to make contact with the distal end of the conductive thin plate spring to cause not only a separation force but also a torsional force in the movable contact plate in the process of contact breaking, the movable contact is easy to be disconnected from the stationary contact even if the existence of the contact fusing, with less energy consumption.

[0020] Also, the driving and returning elastic tongues are formed in the distal ends of different conductive thin plate springs, which reduces the number of components and assembling processes and provides a high productivity for the production of the contact plates.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 

Fig. 1A is a general perspective view showing an electromagnetic relay to which a first embodiment according to the present invention is applied and Fig. 1B is a perspective view showing a state in which a cover is removed from the first embodiment in Fig. 1A.

Figs. 2A and 2B are plan views showing states brought before and after an operation.

Fig. 3 is an exploded perspective view showing the first embodiment illustrated in Fig. 1A.

Fig. 4 is an exploded perspective view seen at a different angle from Fig. 3.

Fig. 5 is a perspective view showing a box-shaped base illustrated in Fig. 1B.

Fig. 6 is an exploded perspective view showing a main part according to the first embodiment illustrated in Fig. 1B.

Figs. 7A, 7B and 7C are front, bottom and rear views showing a contact mechanism portion illustrated in Fig. 3, respectively.

Figs. 8A and 8B are plan and sectional views showing a card illustrated in Fig. 3.

Figs. 9A and 9B are partial enlarged perspective and bottom views in which a movable terminal is removed from a driving mechanism portion illustrated in Fig. 1B.

Figs. 10A and 10B are front and rear views showing a contact mechanism portion according to a second embodiment of the present invention.

Figs. 11A and 11B are a bottom view of a contact mechanism portion and a perspective view of a third conductive thin plate spring illustrated in Fig. 10.

EMBODIMENTS OF THE INVENTION

[0022] With reference to Figs. 1A to 10B, an electromagnetic relay according to an embodiment of the invention will be described.

[0023] An electromagnetic relay according to a first embodiment of the invention includes a box-shaped base 10, an electromagnet block 20, a rotating block 30, a card 40, a contact mechanism 50, a support plate 70 and a cover 80.

[0024] As shown in Fig. 5, the box-shaped base 10, which is configured to be a rectangular thin box, has an interior separated by an insulating wall 11 into first and second cavities 12 and 13. The insulating wall 11 has a cutout 11a defined therein. The box-shaped base 10 has vertical shallow grooves 14a formed in its external side surfaces. The grooves 14a accept engaging portions 14b formed in and projected from the bottom surfaces thereof.

[0025] The first cavity 12 has a bearing 16 provided on a bottom surface thereof for supporting a rotating shaft 34a of the rotating block 30 which will be described below. Positioning concaves 17a and 17b are provided on opposite sides of the bearing 16 for positioning the electromagnet block 20 which will be described below. A concave cutout 18 is provided on an opening edge of the first cavity 12 for positioning a spool 21 of the electromagnet block 20 which will be descried below.

[0026] Terminal grooves 15a and 15b are formed on an open edge of the second cavity 13 for receiving stationary and movable contact terminals 51 and 54 of the contact mechanism 50 which will be described below.

[0027] As shown in Fig. 6, the electromagnet block 20 has a spool 21 with opposite flanges 22a and 22b, a coil 23 wound around the spool 21, an iron core 24 inserted in a through-hole 22c formed in the spool 21, and yokes 25 and 27 fixed on the opposite ends of the iron core 24 projecting from the opposite flanges. Each of the yokes 25 and 27 is made of a T-shaped, punched magnetic plate with transversely extended wide portions 26 and 28, which is then right angled to have an L-shaped configuration. A pair of coil terminals 29 are press inserted in the terminal holes formed in the flange 22a of the spool 21. The opposite ends of the coil 23 are engaged around the respective coil terminals 29 and then soldered.

[0028] Five terminal holes may be formed in parallel in the flange 22a, allowing more coil terminals 29 and/or various arrangements of the coil terminals 29 to be selected as necessary. The coil terminals 29 are not limited to a straight rod-like terminal, and it may be have another configuration such as T-shape.

[0029] The rotating block 30 has a rotating block body 33. The rotating block body 33, which has a permanent magnet (not shown) and a pair of movable iron plates 31 and 32 provided on opposite sides of the permanent magnet, is made by insert molding. The rotating block body 33 has a pair of rotating shafts 34a and 34b coaxially projecting from the opposite upper and lower surfaces of the block body 33 and a driving arm 35 integrally mounted on a side surface of the block body 33. The driving arm 35 has an engaging nail 36 formed on a distal end thereof.

[0030] As shown in Fig. 8, the card 40 has a driving hole 41 provided on one side and an engaging hole 42 provided on the other side. The card 40 also has driving projections provided on one end thereof and projected in the opposite directions so that it has a substantially T-shape. The card 40 further has a fail-safe projection provided adjacent the peripheral edge of the driving hole 41. One driving projection 43 has a greater thickness than the other driving projection 44 so as to prevent the movable contact plate 60 does not contact them simultaneously.

[0031] As shown in Figs. 6 and 7, the contact mechanism 50 has a stationary contact terminal 51 and a movable contact terminal 54. For convenience of description, in Fig. 7 distal ends of the returning elastic tongue 67b and 67c provided on the distal end of the second conductive thin plate spring 65 are removed in part. The stationary contact terminal 51 has a pair of stationary contacts 52 and 53 spaced apart from each other in the widthwise direction and fixed to one end thereof.

[0032] The movable contact terminal 54 supports the movable contact plate 60 fixed to one side thereof and has an operating hole 55 provided on the other side. The movable contact plate 60, which is made of three - first, second and third - conductive thin plate springs 61, 65 and 67 stacked one on top the other, has a pair of movable contacts 56 and 57 spaced apart from each other in the widthwise direction and integrally fixed to the distal end portion of the plate.

[0033] The first conductive thin plate spring 61 has a spring constant adjusting slit 62a extending in a longitudinal direction from the proximal to distal end thereof and a substantially U-shaped fold 63a provided in its mid-portion so as to accommodate its deformation and then ensure a desired operating characteristic thereof. The distal end of the spring 61 is forked into three prongs including a central driving elastic tongue 64a and two reinforcing elastic tongues 64b and 64c provided on opposite sides of the central tongue.

[0034] The second conductive thin plate spring 65 has a spring constant adjusting slit 62b extending in a longitudinal direction from the proximal to distal end thereof and a substantially U-shaped fold 63a provided in its mid-portion so as to accommodate its deformation and then ensure a desired operating characteristic thereof. The second conductive thin plate spring 65 has an engaging cutout 66a formed in a distal, central portion thereof and two prongs provided on opposite sides of the cutout 66a. The prongs have opposing inner edges thereof which are right angled in the same direction to form position regulating elastic tongues 66b and 66c.

[0035] The third conductive thin plate spring 67 has a substantially U-shaped fold 63c provided in its mid-portion so as to accommodate its deformation and then ensure a desired operating characteristic thereof. The distal end of the spring 67 is forked into three prongs including a central driving elastic tongue 64a and two reinforcing elastic tongues which are right angled to form a position regulating elastic tongue 67a and a pair of returning elastic tongues 67b and 67c.

[0036]  The spring constants of the first and second conductive thin plate springs 61 and 65 can be adjusted by changing the widths and/or lengths of the spring constant adjusting slits 62a and 62b. This facilitates the adjustment of the spring loads at making and breaking operations of the contacts, enhancing the design flexibility of the relay.

[0037] As shown in Fig. 3, the support plate 70 has both ends engaged and supported on the opposing opening edges of the box-shaped base 10. The rotating shaft 34b of the rotating block 30 is fitted in the bearing hole 71 formed at the center of the plate 70. Also, the ends 26b and 28b of the wide portions 26 and 28 of the yoke 25 and 27 are fitted in the positioning rectangular holes 72. This causes that the electromagnet block 20 and the rotating block 30 are positioned precisely.

[0038] The cover 80 takes a rectangular configuration capable of covering the opening of the box-shaped base 10, and has an elastic engaging portions 81 extending from respective outer peripheral edges thereof.

[0039] Description will be made to an assembling of the electromagnetic relay.

[0040] As shown in Figs. 3 and 5, the electromagnet block 20 is positioned in the first cavity 12 of the box-shaped base 10 (Fig. 6) with one ends 26a and 28a of the wide portions 26 and 28 of the yokes 25 and 27 fitted in the positioning concaves 17a and 17b on the bottom surface of the first cavity 12 and also with the flange 22a engaged in the cutout 18 of the box-shaped base 10. According to the embodiment, the electromagnet block 20 is positioned in the box-shaped base 10 at several portions, which is advantageous that it is precisely assembled in the box-shaped base. Then, the stationary contact terminal 51 is fitted and positioned in the groove 15a of the second cavity 13.

[0041] As shown in Figs. 3 and 9, the card 40 is inserted in the operating hole 55 of the movable contact terminal 54 and is thus assembled into the movable contact plate 60 fixed to the movable contact terminal 54. For convenience of description, the movable contact terminal 54 is not shown in Fig. 5B.

[0042] Specifically, as shown in Fig. 9, the driving elastic tongue 64a of the first conductive thin plate spring 61 is inserted in the driving hole 41 of the card 40. The card 40 is positioned or held by engaging the position regulating elastic tongues 66b and 66c of the second conductive thin plate spring 65 on the opposite side surfaces of the card 40. Also, the position regulating elastic tongue 67a of the third conductive thin plate spring 67 is engaged on one end of the card 40, and the returning elastic tongues 67b and 67c are engaged on the driving projections 43 and 44 of the card 40 for the vertical positioning of the card. Further, the engaging nail 36 of the rotating block 30 is engaged in the engaging hole 42 of the card 40 and then the card 40 is inserted in the box-shaped base 10. Thereafter, the card 40 is inserted in the operating cutout 11a of the insulating wall 11 of the box-shaped base 10, and the movable contact terminal 54 is press fitted and thereby positioned in the terminal groove 15b. Subsequently, the rotating shaft 34a of the rotating block 30 is fitted in the bearing 16 of the box-shaped base 10 to rotatably support the rotating block 30.

[0043] Furthermore, the opposite ends of the support plate 70 are engaged and supported on the opening edges of the box-shaped base 10, and the rotating shaft 34b of the rotating block 30 is fitted in the bearing hole 71. Also, the other ends 26b and 28b of the wide portions 26 and 28 in the yokes 25 and 27 are fitted and positioned in the positioning rectangular holes 72 and72g. Therefore, the electromagnet block 20 and the rotating block 30 are precisely positioned in the box-shaped base 10, which results in a stable operating characteristic.

[0044] Finally, the cover 80 is positioned to cover the opening portion of the box-shaped base 10, and the elastic engaging portion 81 of the cover 80 is engaged with the engaging portion of the box-shaped base 10, which completes the assembling of the relay.

[0045] An operation of this present embodiment will be described below.

[0046] As shown in Fig. 2A, in the rotating block 30, the end 32a of the movable iron plate 32 is attracted to the wide portion 26 of the yoke 25 and the other end 31b of the movable iron plate 31 is attracted to the wide portion 28 of the yoke 27 by the magnetic force of the permanent magnet (not shown). This causes that the movable contact plate 60 is attracted toward the movable contact terminal 54 against a spring force thereof through the card 40, which results in that the movable contact 56 is disconnected from the stationary contact 52. For convenience of description, the support plate 70 is not shown in Figs. 2A and 2B.

[0047] A voltage is applied to the coil 23 to generate a magnetic force in a direction which overcomes the magnetic force of the permanent magnet in the rotating block 30. This allows that one end 31a of the movable iron plate 31 of the rotating block 30 is attracted to the wide portion 26 of the yoke 25 and the other end 32b of the movable iron plate 32 of the rotating block 30 is attracted to the wide portion 28 of the yoke 27 so that the rotating block 30 is rotated. This allows the driving arm 35 to force the card 40, causing the spring force of the movable contact plate 60 to act on the card 40 through the driving elastic tongue 64a, which slidingly moves the card 40 toward the stationary contact terminal 51. As a result, the movable contact plate 60 is moved away from the movable contact terminal 54 by its spring force so that the movable contacts 56 and 57 are brought into contacts with the stationary contacts 52 and 53. Subsequently, the one end 31a of the movable iron plate 31 of the rotating block 30 is attracted to the wide portion 26 of the yoke 25, and the other end 32b of the movable iron plate 32 is attracted to the wide portion 28 of the yoke 27. This allows that, even if the application of the voltage to the coil 23 is halted, the card 40 is immovably fixed so that the connections between the movable contacts 56 and 57 and the stationary contacts 52 and 53 are maintained. In this state, a distance between the driving projection 43 and the returning elastic tongue 67b is smaller than that between the driving projection 44 and the returning elastic tongue 67c.

[0048] When a voltage is applied to the coil 23 in the opposite direction, the end 32a of the movable iron plate 32 is attracted to the wide portion 26 of the yoke 25, and the other end 31b of the movable iron plate 31 is attracted to the wide portion 28 of the yoke 27, causing the rotating block 30 to rotate in the opposite direction, which results in that the card 40 is pulled by the engaging nail 36 of the rotating block 30 to slidingly move away from the stationary contact terminal 51. The driving projection 43 makes a contact with the returning elastic tongue 67b of the third conductive thin plate spring 67, and then the driving projection 44 makes a contact with the returning elastic tongue 67c. This means that during the breakings of the contacts between the movable and the stationary contacts 56 and 52 and the movable and the stationary contacts 57 and 53 , the card 40 makes a contact with one side of the movable contact plate 60, acting not only a separating force but also a torsional force or moment on the third conductive thin plate spring 67 so that the movable contact 56 is disconnected from the stationary contact 52 and then the movable contact 57 is disconnected from the stationary contact 53. This eases the disconnections between fused, be that as they may, movable and stationary contacts 56, 57 and 52, 53.

[0049] As shown in Figs. 10 to 10A-11B, the second embodiment of the invention is substantially the same as the first embodiment except that, the driving projections 43 and 44 of the T-shaped card 40 have the same configuration and the pair of returning elastic tongues 67b and 67c provided on the distal ends of the third conductive thin plate spring 67 have different bending angles (Fig. 11B).

[0050] Therefore, the driving projection 43 is out of contact with the returning elastic tongue 67b of the third conductive thin plate spring 67 during the contact disconnection or when the driving projection 44 of the card is in contact with the returning elastic tongue 67c of the third conductive thin plate spring 67.

[0051] An operation according to the second embodiment is substantially the same as that in the first embodiment. When an electromagnet block 20 is activated to rotate a rotating block 30 and thereby sliding a card 40, the movable contacts 56 and 57 simultaneously contact the stationary contacts 52 and 53 through the first conductive thin plate spring 61. Even if the voltage application to the coil 23 of the electromagnet block 20 is halted, the card 40 is held in its active position due to the magnetic force of the permanent magnet and then the connection between the movable contacts 56 and 57 and the stationary contacts 52 and 53 is maintained.

[0052] When the voltage is applied to the coil 23 of the electromagnet block 20 in the opposite direction, the rotating block 30 is rotated in the opposite direction so that the card 40 is slidingly moved in the opposite direction through the engaging nail 36 of the rotating block 30. This results in that the driving projection 43 of the card 40 contacts the returning elastic tongue 67c of the third conductive thin plate spring 67 and then the driving projection 44 contacts the returning elastic tongue 67b of the third conductive thin plate spring 67, which generates a torsional moment in the movable contact plate 60. This results in that the card 40 makes a contact with one side of the movable contact plate 60, and then not only the separation force but also the torsional force is applied to the third conductive thin plate spring 67. As a result, the movable contact 57 is disconnected from the stationary contact 53 and then the movable contact 56 is disconnected from the stationary contact 52, which eases the disconnection between fused, be that as they may, movable and stationary contacts 56, 57 and 52, 53.

[0053] The electromagnetic relay according to the invention is not limited to that described above, and the invention can be applied to various electromagnetic relays and electronic devices.

PARTS LIST

[0054] 

10

box-shaped base

11

insulating wall

11a

cutout

12

first cavity

13

second cavity

15a, 15b

terminal groove

16

bearing

17a, 17b

positioning concave

18

cutout

20

electromagnet block

21

spool

22a, 22b

flange

23

coil

24

iron core

25, 27

yoke

26, 28

wide portion

29

coil terminal

30

rotating block

31, 32

movable iron plate

33

block body

34a,

34b rotating shaft

35

driving arm

36

engaging nail

40

card

41

driving hole

42

engaging hole

43

driving projection

45

fail safe projection

50

contact mechanism

51

stationary contact terminal

52, 53

stationary contact

54

movable contact terminal

55

operating hole

56, 57

movable contact

60

movable contact plate

61

first conductive thin plate spring

62a, 62b

spring constant adjusting slit

63a, 63b, 63c

fold

64a

driving elastic tongue

64b, 64c

reinforcing elastic tongue

65

second conductive thin plate spring

66b,

66c position regulating elastic tongue

67

third conductive thin plate spring

67a

position regulating elastic tongue

67b, 67c

returning elastic tongue

70

support plate

71

bearing hole

72

positioning rectangular hole

80

cover

81

elastic engaging portion

Claims

1. A movable contact plate which comprises at least two, stacked conductive thin plate springs, the movable contact plate having one end connected to a movable contact terminal and the other end supporting a movable contact integrally fixed thereto, the movable contact plate being drivingly moved in a thicknesswise direction thereof by an engagement at a distal end thereof with a card to make and break contact with a stationary contact, wherein one of the conductive thin plate springs has at a distal end thereof a driving elastic tongue and the other of the conductive thin plate springs has at a distal end thereof a pair of returning elastic tongues, the pair of returning elastic tongues being configured to take a condition that only one of the returning elastic tongues makes a contact with the card while the movable contact plate is being moved toward a condition where the movable and stationary contacts are disconnected.

2. The movable contact plate according to claim 1, wherein the movable contact plate has three conductive thin plate springs, one of three conductive thin plate springs including an intermediate conductive thin plate spring positioned between another two conductive thin plate springs, the intermediate conductive thin plate spring having at a distal end thereof a position regulating elastic tongue which is configured to engage and regulate opposite sides of the card.

3. The movable contact plate according to claim 1 or 2, wherein at least one of the conductive thin plate springs has a spring constant adjusting slit.

4. The movable contact plate according to any of claims 1 to 3, wherein the conductive thin plate springs have folds defined at mid-portions thereof, the folds being configured to have different sizes so that they are arranged one on top the other.

5. The movable contact plate according to any of claims 1 to 4, wherein the stacked conductive thin plate springs support a pair of movable contacts spaced apart from each other in a widthwise direction of the movable contact plate.

6. An electromagnetic relay comprising the contact mechanism portion according to any of claims 1 to 5.

Drawing