Switching device

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a switching device and, more particularly, to a switching device such as an electromagnetic relay, a switch or a timer for switching an electric current in a closed space.

2. Description of the Related Art

As the switching device for closing the electric current in the closed space, there is a closed type relay device (as referred to Patent Publication 1, for example) in the prior art.

[Patent Publication 1]

JP-T-9-510040 (on pages 13 to 17 and in FIG. 1)

As a coil portion

40

is magnetized and demagnetized, more specifically, a plunger

9

is brought into and out of contact with a core center

4

so that an armature assembly

8

, as integrated with the plunger

9

, and an armature shaft

10

are slit in the axial direction to bring a moving contact disc

21

into and out of contact with stationary contacts

22

and

22

.

In the closed type relay device, a core assembly

2

constructing a magnetic circuit includes the core center

4

, a core base upper portion

5

, a core outer wall

6

and a core base portion

7

, all of which are made of a ferromagnetic substance.

However, the core center

4

contacts with the core base portion

7

only through a thin bottomed cylindrical member (although not designated by numeral) but not directly. This bottomed cylindrical member is thought from the viewpoint of magnetic efficiency to be made of a nonmagnetic material. Therefore, the core assembly

2

has a high magnetic resistance so that it requires a high current for achieving a desired driving force. This raises a problem that the power consumption is high.

SUMMARY OF THE INVENTION

In view of this problem, the invention has an object to provide a switching device of a low power consumption type.

In order to achieve this invention, according to the invention, there is provided a switching device comprising: a contact mechanism block housed in a closed sealing case; and an electromagnet block arranged outside of the sealing case for driving the contact mechanism block, wherein a pair of iron cores constructing the magnetic block have their one-end magnetic pole portions individually arranged on the bottom face of the sealing case and their other end portions connected to each other by a yoke, so that the two end portions of moving iron member of the contact mechanism block are attracted by and leave the magnetic pole portions of the iron cores as the electromagnet block is magnetized and demagnetized.

According to the invention, the moving iron member of the contact mechanism block contacts with the magnetic pole portions or the one-end portions of the paired iron cores constructing the electromagnet block, and the end portions of the iron cores are connected by the yoke. As a result, a magnetic circuit, as continued by the paired iron cores, the yoke and the moving iron member, is formed to provide a switching device obtained having a low magnetic resistance and a small power consumption.

In an embodiment of the invention, moreover, neck portions formed just below the magnetic pole portions of the iron cores may be press-fitted in press-fit holes formed in the bottom face of the sealing case, and the press-fit holes may be clamped at their open edge portions between the open edge portions of cylindrical members press-fitted on the neck portions and the magnetic pole portions of the iron cores. The sealing case may be made of a material having a larger coefficient of thermal coefficient than that of the iron cores.

According to this embodiment, the sealing case is made of a material having a larger coefficient of thermal coefficient than that of the iron cores. Even if the temperature rises so that the iron cores expand, therefore, the expansion of the sealing case in the thickness direction is larger than those of the iron cores so that the open edge portion of the sealing case is firmly clamped between the magnetic pole portions of the iron cores and the open edge portions of the cylindrical members.

Even if the temperature drops so that the iron cores shrink, on the other hand, the shrinkage of the press-fit holes of the sealing case in the diametrical direction is larger than those of the iron cores so that the sealing case fastens the neck portions of the iron cores. As a result, there is obtained an effect that to provide a closed type switching device, in which the gas-tightness is not deteriorated even if the temperature changes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a perspective view showing an embodiment of the case, in which a switching device according to the invention is applied to a DC current breaking relay;

FIG. 2

is an exploded perspective view of

FIG. 1

;

FIG. 3

is an exploded perspective view of a relay body shown in

FIG. 2

;

FIG. 4

is an exploded perspective view of an electromagnet block shown in

FIG. 3

;

FIG. 5

is an exploded perspective view of a sealing case shown in

FIG. 4

;

FIGS. 6A and 6B

are enlarged sectional views showing a method for caulking the sealing case shown in

FIG. 5

;

FIGS. 7A and 7B

are exploded perspective views of a moving contact block shown in

FIG. 3

;

FIGS. 8A and 8B

are exploded perspective views of a stationary contact block shown in

FIG. 3

;

FIGS. 9A and 9B

are exploded perspective views of the stationary contact block shown in

FIG. 3

;

FIG. 10

is a longitudinal section of the switching device shown in

FIG. 1

;

FIGS. 11A and 11B

are partially enlarged sectional views of

FIG. 10

;

FIG. 12

is a longitudinal section showing the relay of the embodiment according to the invention and taken at a different angle;

FIGS. 13A and 13B

are partially enlarged views of

FIG. 12

;

FIG. 14

is a transverse section of the switching device shown in

FIG. 1

; and

FIG. 15

is a schematic diagram showing an ark breaking mechanism according to an embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiment according to the invention will be described with reference to

FIG. 1

to FIG.

15

. The first embodiment of the invention is applied to a DC load switching relay, in which a relay body

20

is housed in a space defined by a box-shaped case

10

and a box-shaped cover

15

integrated, as shown in FIG.

1

and FIG.

2

.

The box-shaped case

10

is provided, as shown in

FIG. 2

, with: a recess

11

for housing a later-described electromagnet block

30

; fixing through holes

12

in a pair of plane corners positioned on a diagonal line; and connecting recesses

13

positioned in the remaining plane corners. In the connecting recesses

13

, connecting nats (not shown in the figure) are embedded.

The box-shaped cover

15

is so shaped that it can fit the box-shaped case

10

and can house a later-described sealing case block

40

. In the ceiling of the box-shaped cover

15

, moreover, there are formed connecting holes

16

and

16

, from which there are protruded connecting terminals

75

and

85

of the relay body

20

. From the ceiling of the box-shaped cover

15

, moreover, there are protrusions

17

and

17

for housing a gas vent pipe

21

. The protrusions

17

and

17

are connected through a partition wall

18

and have a function as an insulating wall together. By engaging engaged holes

19

, which are formed in the edge portion of the lower opening of the box-shaped cover

15

, with engaging pawls

14

, which are formed on the edge portion of the upper opening of the box-shaped case

10

, moreover, the cover

15

and the case

10

are integrally jointed to each other.

In the relay body

20

, as shown in

FIG. 3

, a contact mechanism block

50

is sealed in the sealing case block

40

mounted on the electromagnet block

30

.

This electromagnet block

30

is so integrated that a pair of spools

32

wound with coils

31

are juxtaposed to each other around two iron cores

37

and through a yoke

39

.

Relay terminals

34

and

35

are individually press-fitted on the two opposed side end faces of the lower one

32

a

of flange portions

32

a

and

32

b

at the two ends of the spools

32

. And, the coil

31

wounded on the spools

32

is bound and soldered at its one-end portion to the one-end portion (or bind portions)

34

a

of one relay terminal

34

and is bound and soldered at its other end (bind portion) to one-end portion (or bind portion)

35

a

of the other relay terminal

35

. In the relay terminals

34

and

35

, moreover, not only the bind portions

34

a

but also other end portions (or joint portions)

35

b

are bent up. Of the relay terminals

34

and

35

assembled with the juxtaposed spools

32

and

32

, the joint portion

35

b

of the relay terminal

35

and the bind portion

34

a

of the other relay terminal

34

are jointed and soldered to each other. Of the adjacent relay terminals

35

and

34

, moreover, the bind portion

35

a

and a joint portion

34

b

are jointed and soldered to each other. Thus, the two coils

31

and

31

are connected. Moreover, the paired flange portions

32

a

and

32

b

of the spools

32

are individually spanned with coil terminals

36

and

36

and connected to the joint portions

34

b

and

35

b

of the relay terminals

34

and

35

. (

FIG. 3

)

The sealing case block

40

is constructed to include a sealing case

41

capable of housing the later-described contact mechanism block

50

, and a sealing cover

45

for sealing the opening of the sealing case

41

. In the bottom face of the sealing case

41

, there are formed a pair of press-fit holes

42

(

FIG. 5

) for press-fitting the icon cores

37

. In the sealing cover

45

, on the other hand, there are formed a pair of insert holes

46

and

46

capable of inserting the connecting terminals

75

and

85

of the later-described contact mechanism block

50

, and a loosely fitting hole

47

capable of fitting the gas vent pipe

21

loosely.

The electromagnet block

30

and the sealing case

40

are assembled in the following procedure.

First of all, the relay terminals

34

and

35

are individually press-fitted in the flange portions

32

a

of the spools

32

whereas the coils

31

are wound on the spools

32

, and the lead wires are individually bound on the soldered to the bind portions

34

a

and

35

a

of the relay terminals

34

and

35

. Next, there are juxtaposed the paired spools

32

, from which the bind portions

34

a

and

35

a

and the joint portions

34

b

and

35

b

of the relay terminals

34

and

35

are bent up. Moreover, the bind portion

35

a

of the relay terminal

35

and the joint portion

34

b

of the other relay terminal

34

are jointed and soldered to each other. Moreover, the coils

31

and

31

are connected by jointing and soldering the joint portion

35

b

of the relay terminal

35

and the bind portion

34

a

of the other relay terminal

34

.

As shown in

FIG. 5

, on the other hand, the iron cores

37

are individually inserted into the press-fit holes

42

formed in the bottom face of the sealing case

41

, and pipes

38

are fitted on the protruding stems

37

a

of the iron cores

37

. And, the iron cores

37

are pushed in the axial direction from the open edge portions of the pipes

38

. As shown in

FIG. 6

, the iron core

37

is made smaller at the diameter D1 of its stem portion

37

a

than the diameter d1 of the press-fit hole

42

of the sealing case

41

and the internal diameter d2 of the pipe

38

. However, the diameter D2 of the neck portion

37

b

of the iron core

37

is made larger than the diameter d1 of the press-fit hole

42

of the sealing case

41

and the internal diameter d2 of the pipe

38

. When the iron core

37

is pushed in the axial direction, the neck portion

37

b

of the iron core

37

is press-fitted in the press-fit hole

42

of the sealing case

41

while widening it and the internal diameter of the pipe

38

. Moreover, the open edge portion of the pipe

38

and the head portion (or magnetic pole portion)

37

c

of the iron core

37

push the open edge portion of the press-fit hole

42

of the sealing case

41

from above and below. There, the open edge portion of the press-fit hole

42

of the sealing case

41

is caulked and fixed from the three sides.

According to this embodiment, the sealing case

41

is made of such a material, e.g., aluminum as has a larger coefficient of thermal expansion than those of the iron cores

37

and the pipes

38

. Therefore, the embodiment is advantageous in that the gas-tightness is not deteriorated even if the temperature changes.

The reason for this advantage will be described in the following. Even if the temperature rises so that the individual parts expand, the expansion of the sealing case

41

in the thickness direction is larger than those of the remaining parts so that the sealing case

41

is firmly clamped between the head portions

37

c

of the iron cores

37

and the pipes

38

. Even if the temperature drops so that the individual parts shrink, on the other hand, the shrinkage of the press-fit holes

42

of the sealing case

41

in the diametrical direction is larger than those of the remaining parts so that the sealing case

41

fastens the neck portions

37

b

of the iron cores

37

.

In order to prevent the thermal stress while retaining the gas-tightness, it is preferred that the iron cores

37

and the pipes

38

have substantially equal coefficients of thermal expansion.

Then, the iron cores

37

and the pipes

38

are individually inserted into center holes

32

c

of the spools

32

, and the leading end portions of the protruding iron cores

37

are inserted into and caulked by caulking holes

39

a

of the yoke

39

. Thus, the electromagnet block

30

is completed while mounting the sealing case

41

. Between the yoke

39

and the flange portions of the spools

32

, there is sandwiched an insulating sheet

39

b

(

FIG. 4

) for enhancing the insulating performance.

Next, the paired flange portions

32

a

and

32

b

of the spools

32

are individually spanned with the coil terminals

36

, and the lower end portions of these coil terminals

36

are jointed to the joint portions

34

b

and

35

b

of the relay terminals

34

and

35

.

The contact mechanism block

50

is constructed, as shown in

FIG. 3

, to include a moving contact block

60

, stationary contact blocks

70

and

80

assembled on the two sides of the moving contact block

60

, and an insulating case

90

fitted to integrate those blocks

60

,

70

and

80

.

The moving contact block

60

is constructed, as shown in

FIG. 7A

, by assembling a pair of juxtaposed moving contact members

62

and

63

and contact springs

64

individually with a moving insulating bed

61

. The moving insulating bed

61

is constructed, as shown in

FIG. 7B

, such that a leg portion

61

a

having a generally cross-shape section is protruded from the lower face of its central portion and such that a moving iron member

67

is caulked and fixed on its two side portions through rivets

66

having coiled return springs

65

fitted thereon. The moving iron member

67

is covered on its lower face with a shielding sheet

68

.

A pair of retained protrusions

62

a

and

63

a

are individually protruded from the one-side edge portions of the band-shaped conductive materials of the moving contact members

62

and

63

. Of the moving contact members

62

and

63

, the moving contact member

62

is made of a band-shaped conductive member of molybdenum having a high melting point and capable of enduring a rush current, and the other moving contact member

63

is made of a thick band-shaped copper sheet plated with silver.

The contact springs

64

are arranged for applying a contact pressure to the moving contact members

62

and

63

. And, the contact springs

64

are made by bending band-shaped spring materials generally into an angle shape and are folded at their two side edge portions to form retained pawls

64

a

and

64

a.

These retained pawls

64

a

of the contact springs

64

are retained on the two end portions of the moving contact members

62

and

63

, when the moving contact members

62

and

63

and the contact springs

64

and

64

are inserted into and assembled with a pair of assembling holes

61

b

and

61

c

juxtaposed in the movinginsulating bed

61

. As a result, the moving contact members

62

and

63

can be prevented from becoming vertically loose. Moreover, the retained protrusions

62

a

and

63

a

of the moving contact members

62

and

63

are retained on the open edge portions of the assembling holes

61

b

and

61

c

of the moving insulating bed

61

, so that the contact springs

64

and the moving insulating beds

62

and

63

can be prevented from coming out. By positioning the moving contact member

62

at a lower height than that of the moving contact member

63

, moreover, a step is formed between the paired moving contact members

62

and

63

. As a result, the moving contact member

62

comes into contact with a stationary contact

78

a

before the moving contact member

63

comes into contact with a stationary contact

78

b.

The stationary contact blocks

70

and

80

are constructed, as shown in FIG.

8

and

FIG. 9

, such that stationary contact beds

71

and

81

molded of a resin to have an identical shape are assembled with stationary contact terminals

76

and

86

, as made of a generally C-shaped section caulking and fixing the connecting terminals

75

and

85

, and permanent magnets

77

and

87

. The stationary contact beds

71

and

81

are constructed such that abutting protrusions

72

and

82

are individually protruded inward sideways and such that supporting leg portions

73

and

83

are individually protruded vertically downward.

The stationary contact terminals

76

and

86

are formed to have pairs of stationary contacts

78

a

and

78

b

, and

88

a

and

88

b

, respectively, by protruding their lower side edge portions. On the other hand, the permanent magnets

77

and

87

are assembled such that their pole-faces

77

a

and

87

a

are jointed to the inner faces of the stationary contact terminals

76

and

86

. As a result, the pole-faces

77

a

and

87

a

of the permanent magnets

77

and

87

are positioned near the paired stationary contacts

78

a

and

78

b

, and

86

a

and

86

b.

The insulating case

90

is provided for uniting the contact mechanism block

50

, as shown in FIG.

3

. And, the paired stationary contact blocks

70

and

80

are assembled from the two sides with the moving contact block

60

and are then fitted thereon, so that the connecting terminals

75

and

85

are protruded from terminal holes

91

and

91

of the insulating case

90

. This insulating case

90

is provided with a pair of gas vent holes

92

near the terminals holes

91

. The reason for the paired gas vent holes

92

is to eliminate the directivity at the assembling time.

Here will be described the procedure for assembling the contact mechanism block

50

.

At first, the moving iron member

67

and the shielding sheet

68

are assembled with the moving insulating bed

61

through the rivets

66

inserted into the return springs

65

. And, the moving contact members

62

and

63

and the contact springs

64

and

64

are assembled with the moving insulating bed

61

. Next, the stationary contact blocks

70

and

80

are assembled from the two sides of the moving insulating bed

61

while raising the lower end sides of the return springs

65

, thereby to bringing the abutting protrusions

72

and

82

into abutment against each other. Moreover, the insulating case

90

is fitted on the stationary contact blocks

70

and

80

. Thus, the contact mechanism block

50

is completed.

Next, the contact mechanism block

50

is inserted into the sealing case

41

mounted on the electromagnet block

30

. Then, the leg portions

73

and

83

of the stationary contact blocks

70

and

80

abut against the head portions

37

c

or the magnetic pole portions of the iron cores

37

so that the moving iron member

67

can come close to and apart from the magnetic pole portions

37

c

through the shielding sheet

68

. And, the sealing cover

45

is fitted in and welded integrally with the sealing case

41

. Moreover, the gas vent pipe

21

is press-fitted from the loosely fitting hole

47

into the gas vent hole

92

of the insulating case

90

. Next, a sealing material (although not shown) is injected onto the sealing cover

45

and is solidified to seal around the base portions of the connecting terminals

75

and

85

and the gas vent pipe

21

. And, the air in the sealing case

40

is vented from the gas vent pipe

21

, and a predetermined mixture gas is injected. After this, the gas vent pipe

21

is caulked and sealed. And, the paired flange portions

32

a

and

32

b

of the spools

32

are spanned with the coil terminals

36

. Thus, the relay body

20

is completed.

And, this relay body

20

is housed in the recess

11

of the case

10

, and the coil terminals

36

are arranged in the connecting recesses

13

. Moreover, the cover

15

is assembled with the case

10

. Thus, the DC current breaking relay is completed.

Here will be described the actions of the relay thus constructed.

First of all, in case no voltage is applied to the coils

31

of the electromagnet block

30

, the moving insulating bed

61

is pulled up (

FIG. 13A

) by the spring forces of the return springs

65

and

65

. As a result, the moving iron member

67

leaves the magnetic pole portions

37

c

of the iron cores

37

, and the two end portions of the moving contact members

62

and

63

leave the stationary contacts

78

a

and

88

a

, and

78

b

and

88

b

, respectively.

When a voltage is applied to the coils

31

, moreover, the magnetic pole portions

37

c

of the iron cores

37

attract the moving iron member

67

so that the moving iron member

67

moves downward against the spring forces of the return springs

65

. As a result, the moving insulating bed

61

, as integrated with the moving iron member

67

, moves downward so that the two end portions of the moving contact member

62

come into contact with the stationary contacts

78

a

and

88

a

. Next, the two end portions of the moving contact member

63

come into contact with the stationary contacts

78

b

and

88

b

so that the moving iron member

67

is attracted by the magnetic pole portions

37

c

of the iron cores

37

(FIG.

13

B).

Next, when the application of the voltage to the coils

31

is interrupted, the moving insulating bed

61

is pushed upward by the spring forces of the return springs

65

so that the moving iron member

67

leaves the magnetic pole portions

37

a

of the iron cores

37

together with the moving insulating bed

61

. After the two end portions of the moving contact member

63

left the stationary contacts

78

b

and

88

b

, moreover, the two end portions of the moving contact member

62

leave the stationary contacts

78

a

and

88

a.

An arc current, if produced when the two end portions of the moving contact member

62

leave the stationary contacts

78

a

and

88

a

, is attracted and broken by the magnetic forces of the permanent magnets

77

and

87

. This point will be described in detail with reference to FIG.

14

and FIG.

15

.

As shown in

FIG. 15

, for example, the magnetic flux of the permanent magnet

77

is emitted, as indicated by arrows, from the pole-face

77

a

. When the moving iron member

67

returns, moreover, the end portion of the moving contact member

63

leaves the stationary contact

78

b

, and the end portion of the moving contact member

62

leaves the stationary contact

78

a

. As a result, an arc current A begins to build up from the stationary contact

78

a

. According to Freming's left-hand law (or by the Lorentz's force), however, the arc current A is attracted by the magnetic force of the permanent magnet

77

, and it shifts its production place to the stationary contact

78

b

and turns into an arc current B. Moreover, this arc current B is extended into an arc current C by the magnetic force of the permanent magnet

77

so that it is finally cut and broken.

In this embodiment, the arc current is so extended on the basis of the Freming's left-hand law as to whirl along the pole-faces

77

a

and

87

a

of the permanent magnets

77

and

87

, until it is broken. Therefore, a large space is not required for breaking the arc current unlike the examples of the prior art, so that the device can be small-sized.

This embodiment has been described on the case, in which the DC current is broken, but may be applied to the case in which an AC current is broken. It is natural that the embodiment can also be applied not only to the relay but also to a switch, a timer or the like.

According to the invention, the moving iron member of the contact mechanism block contacts with the magnetic pole portions or the one-end portions of the paired iron cores constructing the electromagnet block, and the end portions of the iron cores are connected by the yoke. As a result, a magnetic circuit, as continued by the paired iron cores, the yoke and the moving iron member, is formed to bring about an effect that the switching device obtained has a low magnetic resistance and a small power consumption.

Switching device

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (1)

US Referenced Citations (1)

Foreign Referenced Citations (1)