Fuse assembly

BACKGROUND OF THE INVENTION

(1). Field of the Invention

This invention relates to a fuse assembly and more specifically, to a fuse assembly that can securely halt an electric power supply to a load after a blowout of a fuse element in the fuse assembly.

(2). Description of the Related Art

In a vehicle as a mobile unit, many electric power transfer lines for transferring electric power itself or signals, such as busbars in an electric junction box such as a junction block, relay box and fuse block, and terminals of a connector for electric connection, are disposed.

In the electric power transfer lines, a fuse block, in which many fuses that can be inserted or extracted are disposed, is employed to protect electric circuits of various electrical equipments. (The fuse block may be called a relay box, junction block or electric junction box as the general term since the fuse block may have relays or busbars. In this specification, the aforementioned fuse block, relay box and junction block are hereinafter called an electric junction box as the general term.)

For example, a fuse assembly

101

shown in

FIG. 5

has been employed as a fuse for use in the electric junction box. As shown in

FIGS. 5 and 6

, the fuse assembly

101

includes a pair of terminals

102

arranged in parallel with each other, a housing

104

for receiving ends

103

of the terminals

102

, and a fuse element

105

formed integrally with a pair of the terminals

102

for connecting the terminals

102

with each other.

The terminal

102

is made of an electrically conductive metal and is formed in a blade-shape as shown in FIG.

6

. The terminal

102

is provided with a plurality of through holes

106

. Each terminal

102

shown in

FIGS. 5 and 6

has two through holes

106

. The through holes

106

are disposed in parallel with each other along the direction of the length of the terminal

102

. One through hole

106

is formed at the center

107

of the terminal

102

along the direction of the length of the terminal

102

and another through hole

102

is formed around the end

103

of the terminal

102

.

When the fuse assembly

101

is mounted in the electric junction box, each opposite end

108

of a pair of the terminals

102

is connected to respective receiving terminals of the electric junction box. An electric power is supplied to one of the receiving terminals from an electric power source or the like, while various loads are electrically connected to an opposite receiving terminal.

An electric power is supplied to one of the terminals

102

through the receiving terminal and the like, while the load is connected to another terminal

102

. Each end

103

of the terminals

102

is received into the housing

104

with each inner surface

109

of the terminals

102

facing with each other.

The housing

104

is made of insulating synthetic resin and the like. The housing

104

is formed in a box-shape. The inside of the housing

104

is a receiving space for receiving each end

103

of a pair of the terminals

102

. The housing

104

is provided with each projection (not shown in the figure) for engaging with the respective through holes

106

. When each projection is engaged with the respective through hole

106

, a pair of the terminals

102

is fixed in the housing

104

.

As shown in

FIG. 6

, the fuse element

105

connects the terminals

102

with each other. Each end of the fuse element

105

is connected to the inner surface

109

situated at the center

107

of the terminal

102

. The thickness of the fuse element

105

is about uniformly formed between one connection part

105

a

connecting with one terminal

102

and another connection part

105

b

connecting with another terminal

102

. The fuse element

105

blows out when a current of an electric power supplied from one of the terminals

102

exceeds a predetermined current value.

As to the fuse assembly

101

mounted in the electric junction box, when a current value of an electric power supplied to the one terminal

102

through the one receiving terminal or the like exceeds a predetermined current value, the fuse element

105

blows out so as to halt the power supply to the load.

As to a conventional fuse

101

shown in

FIG. 5

, the thickness of the fuse element

105

is about uniformly formed between one connection part

105

a

connecting with one terminal

102

and another connection part

105

b

connecting with another terminal

102

. The fuse element

105

tends to blow out at the thinnest portion thereof. The thinnest portion may be located at any portion of the fuse element

105

between one connection part

105

a

and another connection part

105

b

, due to a variation in the manufacturing process. That is, the thinnest portion of the fuse element

105

may be different among the fuse assemblies

101

.

Therefore, as to the conventional fuse assembly

101

, the fuse element

105

may blow out at any portion of the fuse element

105

between one connection part

105

a

and another connection part

105

b

. For example, when the fuse element

105

blows out in the vicinity of one connection part out of the connection part

105

a

and the connection part

105

b

, the fuse element

105

connected to an opposite connection part becomes in a so-called cantilever state.

At this time, due to a vibration of the vehicle during the traveling or a sudden acceleration, the fuse element

105

vibrates in the housing

104

and then, a pair of the blown-out portions of the fuse element

105

may come into contact with each other, resulting in that the blown-out fuse element

105

may electrically connect a pair of the terminals

102

with each other.

SUMMARY OF THE INVENTION

It is therefore an objective of the present invention to solve the above problem and to provide a fuse assembly which can securely halt an electric power supply to a load after a blowout of a fuse element in the fuse assembly.

In order to attain the above objective, the present invention is to provide a fuse assembly comprising: a pair of terminals arranged in parallel with each other; a housing for receiving each one end of a pair of the terminals; and a fuse element for connecting a pair of the terminals with each other, wherein a thickness of the fuse element at the central part thereof situated at the center between a pair of the terminals is smaller than the thickness of the fuse element at each connection part with the terminal.

According to the fuse assembly described above, since a thickness of the fuse element at the central part thereof situated at the center between a pair of the terminals is formed smaller than a thickness of the fuse element at each connection part with the terminal, therefore the central part of the fuse element blows out.

The thickness of the fuse element continuously or gradually decreases from said each connection part to said central part of the fuse element.

According to the fuse assembly described above, the central part of the fuse element securely blows out.

The fuse element comprises: a pair of supporting parts which contains said connection parts and is connected to each end surface situated at an end of a pair of the terminals, said central part connecting a pair of the supporting parts with each other; and a fixing part for fixing each supporting part of the fuse element to the housing.

According to the fuse assembly described above, since the fixing part fixes each supporting part of the fuse element to the housing, therefore the fuse element hardly vibrates in relation to the terminals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a perspective view of a fuse assembly according to a preferred embodiment of the present invention;

FIG. 2

is a sectional view taken along II—II line in

FIG. 1

;

FIG. 3A

is a view illustrating terminals and a fuse element of the fuse assembly shown in

FIG. 1

;

FIG. 3B

is a view viewed from a direction of arrow III B in

FIG. 3A

;

FIG. 4

is a view illustrating a process for molding terminals and a fuse element of the fuse assembly shown in

FIG. 1

;

FIG. 5

is a perspective view of a conventional fuse assembly; and

FIG. 6

is a view illustrating terminals and a fuse element of the conventional fuse assembly shown in FIG.

5

.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, a fuse assembly according to a preferred embodiment of the present invention will be explained with reference to

FIGS. 1

to

4

. As shown in

FIGS. 1 and 2

, the fuse assembly

1

according to the preferred embodiment has a pair of terminals

2

arranged in parallel with each other, a housing

4

for receiving ends

3

a

of the terminals

2

, a fuse element

5

for connecting a pair of the terminals

2

with each other, a fixing part

30

, and a second fixing part

31

.

Each terminal

2

formed in a blade-shape is made of an electrically conductive material and a pair of the terminals

2

is arranged in parallel with each other. In the terminal

2

, one end

3

a

thereof is received into the housing

4

and an opposite end

3

b

thereof is exposed the outside of the housing

4

. As shown in

FIGS. 2 and 3A

, the terminal

2

has a notched part

6

and a protrusion

26

protruding inwardly in the housing

4

.

The notched part

6

is provided to the end

3

a

. The notched part

6

is formed concave in a direction, in which a pair of the terminals

2

aparts from each other from an end surface

27

(described later) of the protrusion

26

. The notched part

6

is formed so that a distance between the two terminals

2

increases gradually from a distance between the two protrusions

26

.

The notched part

6

has: a flat surface

10

extending toward the center along a direction of the length of the terminal

2

starting from an end surface

8

, which is situated at the end

3

a

of the terminal

2

; and a step surface

11

which continues the flat surface

10

to an end surface

27

of the protrusion

26

.

The flat surface

10

is formed flat along the direction of the length of the terminal

2

. A distance between the two flat surfaces

10

is formed longer than that between two inner surfaces

9

of the opposite end

3

b

of the terminal

2

.

The step surface

11

is formed along a direction in which a pair of the terminals

2

aparts or approaches with each other, that is, a direction in which the terminals

2

are arranged in parallel. The notched part

6

is received in the housing

4

when the terminal

2

is mounted in the housing

4

.

The protrusion

26

is provided to the end

3

a

of the terminal

2

. The protrusion

26

is provided at a little center side of the terminal from compared to notched part

6

. The protrusion

26

protrudes in a direction that a pair of the terminals

2

approaches with each other from the respective inner surface

9

. The protrusion

26

has the end surface

27

and a concaved part

28

formed concave from the end surface

27

.

The end surface

27

is formed flat along a direction of the length of the terminal

2

. The concaved part

28

is formed concave in a direction that a pair of the terminals

2

aparts from each other from the end surface

27

.

In the figure, the two concaved parts

28

are provided to one end surface

27

, that is, to one terminal

2

. The protrusion

26

is received in the housing

4

when the end

3

a

of the terminal

2

is received in the housing

4

.

When the fuse assembly

1

is mounted in an electric junction box, each opposite end

3

b

of the respective terminal

2

is electrically connected to a receiving terminal and the like of the electric junction box. An electric power from a power source and the like is supplied to one of the receiving terminal. Various loads are electrically connected to an opposite receiving terminal. Therefore, an electric power is supplied to one terminal

2

out of the two terminals

2

through the receiving terminal, while a load is connected to an opposite terminal

2

.

The housing

4

is made of an insulating synthetic resin and the like. The housing

4

is formed in a box-shape and has a pair of end walls

12

a

and

12

b

, a pair of side walls

13

a

and

13

b

, and a pair of body walls

14

as shown in FIG.

2

.

A pair of the end walls

12

a

and

12

b

faces with each other along a direction crossing with the direction in which a pair of the terminals

2

is arranged in parallel. A pair of the end walls

12

a

and

12

b

faces with each other along the direction of the length of the terminal

2

. A pair of the end walls

12

a

and

12

b

is in parallel with the end surface

8

when the housing

4

receives terminals

2

. The end wall

12

a

out of a pair of the end walls faces the end surface

8

of the terminal

2

with leaving a space therebetween. In the figure, a pair of the end walls

12

a

and

12

b

faces with each other along a direction crossing with the direction, in which a pair of the terminals

2

is arranged in parallel.

A pair of the side walls

13

a

and

13

b

faces with each other along the direction in which a pair of the terminals

2

is arranged in parallel. A pair of the side walls

13

a

and

13

b

is formed along the direction of the length of the terminal

2

.

A pair of the body walls

14

faces with each other along a direction crossing with the direction in which a pair of the terminals

2

is arranged in parallel. The body wall

14

extends along the length of the terminal

2

. The body wall

14

continues to a pair of the end walls

12

a

and

12

b

and a pair of the side walls

13

a

and

13

b

. In

FIG. 2

, only a body wall

14

situated at the depths in the figure is shown.

A space

20

(shown in FIG.

2

), which is surrounded by an inner surface

15

a

of the end wall

12

a

, the end wall

12

b

, inner surfaces

16

a

and

16

b

of the side walls

13

a

and

13

b

, respectively, and an inner surface

17

of the body wall

14

, forms a room for receiving the end

3

a

of the terminal

2

.

A pair of through holes

18

which can insert the respective terminals

2

is formed on the end wall

12

b

, which is situated near to the center of the terminal

2

, out of a pair of the end walls

12

a

and

12

b.

The housing

4

has a partition wall

21

and a second partition wall

22

. The partition wall

21

extends from the inner surface

15

a

of the end wall

12

a

, which faces the respective end surface

8

with leaving a space therebetween, toward the end wall

12

b

. The partition wall

21

extends along the direction of the length of the side walls

13

a

and

13

b

, and the terminal

2

.

The partition wall

21

is provided between a pair of the terminals

2

along a direction in which the terminals are arranged in parallel with each other. The partition wall

21

partitions the space

20

formed in the housing

4

into a first space

24

for receiving the end

3

a

of one terminal out of a pair of the terminals

2

and a second space

25

for receiving the end

3

a

of an opposite terminal out of a pair of the terminals

2

. The first space

24

is situated at left and the second space

25

is situated at right in the figure.

The second partition wall

22

has a base wall

33

, a horizontal wall

34

, and a pair of partitions

35

. The base wall

33

extends from an edge of the through hole

18

of the end wall

12

b

toward the inner surface

15

a

of the end wall

12

a

along the direction of the length of the terminal

2

. The base wall

33

is arranged between the inner protrusion

26

of a pair of the terminals

2

. The base wall

33

has a plurality of protrusions

36

engaging with the concaved parts

28

. The base wall

33

covers the end surface

27

of the terminal

2

when the end

3

a

of the terminal

2

is received in the space

20

.

The horizontal wall

34

continues to an end of the base wall

33

situated away from the end wall

12

b

. The horizontal wall

34

extends along the direction in which a pair of the terminals

2

is arranged in parallel with each other. The horizontal wall

34

extends from an end near to the inner surface

15

a

of the base wall

33

toward both of a pair of the terminals

2

. The horizontal wall

34

is formed along the step surface

11

. The horizontal wall

34

covers the step surface

11

of the terminal

2

when the end

3

a

of the terminal

2

is received in the space

20

.

A pair of the partitions

35

continues to both ends of the horizontal wall

34

near to a pair of the terminals

2

. A pair of the partitions

35

extends from both ends of the horizontal wall

34

toward the inner surface

15

a

and is formed along a flat surface

10

of the notched part

6

of the terminal

2

.

A pair of the partitions

35

is arranged in parallel with each other along the direction in which a pair of the terminals

2

is arranged in parallel with each other. Each partition

35

is provided between each inner surface

16

a

and

16

b

of the side wall

13

a

and

13

b

, respectively, and the partition wall

21

, along the direction in which a pair of the terminals

2

is arranged in parallel with each other. A pair of the partitions

35

covers the flat surface

10

of the terminal

2

when the end

3

a

of the terminal

2

is received in the space

20

.

As shown in

FIGS. 2 and 3A

, the fuse element

5

connects a pair of the terminals

2

with each other. The fuse element

5

is integrally formed with a pair of the terminals

2

. The fuse element

5

is formed in a line shape with its cross section being rectangular shape. The fuse element

5

is formed to have a dimension of width, thickness T

2

(shown in

FIG. 3B

) and length at the central part

40

thereof (explained later) so that the fuse element

5

blows out when the current exceeds a predetermined value.

The fuse element

5

connects the end surfaces

8

of the terminal

2

with each other. As shown in

FIGS. 2

,

3

A and

3

B, the fuse element

5

has a pair of supporting parts

39

and the central part

40

as a fuse part.

Each supporting part

39

has a first extended part

41

and a second extended part

42

. The first extended part

41

extends from the end surface

8

toward the inner surface

15

a

of the end wall

12

a

, that is, in a direction of leaving from a pair of the terminals

2

.

The first extended part

41

is formed in a belt shape with one end being connected to the end surface

8

. The first extended part

41

is provided between each inner surface

16

a

or

16

b

and the partition

35

along the direction, in which the terminals

2

are arranged in parallel with each other.

The first extended part

41

runs parallel to the side wall

13

a

and

13

b

, the base wall

33

, the partition

35

and the partition wall

21

. The first extended part

41

corresponds to the connection part described in this specification.

The second extended part

42

is formed in a belt shape with one end being connected to the first extended part

41

. The second extended part

42

extends from an end

41

a

, which is away from the end surface

8

of the first extended part

41

, in a direction of approaching with each other. The second extended part

42

is provided between an end of the partition

35

and the inner surface

15

a

of the end wall

12

a

. The second extended part

42

is formed along the inner surface

15

a

of the end wall

12

a

and the horizontal wall

34

.

As shown in

FIG. 3B

, a thickness T

1

of the supporting part

39

is smaller than a thickness TO of the terminal

2

. The thickness T

1

corresponds to a thickness of the first extended part

41

, that is, a thickness of the connection part.

The central part

40

is situated at the center between the two terminals

2

along the direction in which a pair of the terminals

2

is arranged in parallel with each other. The central part

40

has a pair of third extended parts

43

and the center

44

. The third extended part

43

is formed in a belt shape with one end being connected to the second extended part

42

. The third extended part

43

extends from an end, to which each second extended part

42

approachs with each other, in a direction of approaching the terminal

2

along the direction of the length of the terminal

2

.

The third extended part

43

is provided between a pair of the partitions

35

and the partition wall

21

along the direction in which a pair of the terminals

2

is arranged in parallel with each other. The third extended part

43

runs parallel to the base wall

33

, a pair of the partitions

35

, the inner surface

16

a

and

16

b

, and the partition wall

21

.

The center

44

is formed in a belt shape with connecting ends, at which the third extended part

43

most approaches the terminal

2

, with each other. The center

44

is provided between the partition wall

21

and the horizontal wall

34

. The center

44

is formed along the inner surface

15

a

of the end wall

12

a

, the end wall

12

b

, and the horizontal wall

34

. The center

44

is situated at the center between the two terminals

2

along the direction in which a pair of the terminals

2

is arranged in parallel with each other.

As shown in

FIG. 3B

, a thickness T

2

of the central part

40

is smaller than a thickness T

1

of the supporting part

39

.

Thus, the fuse element

5

, which has the first to third extended part

41

to

43

, respectively, and the center

44

, is formed bent situating from one terminal

2

to another terminal

2

.

The fuse element

5

is formed in a manner that a thickness T

1

of the first extended part

41

is larger than a thickness T

2

of the center

44

. The fuse element

5

, which has the supporting part

39

having the thickness T

1

and the central part

40

having the thickness T

2

, is formed in a manner that the thickness thereof decreases gradually in a direction from the first extended part

41

to the center

44

, that is, the central part

40

.

As shown in

FIG. 4

, a belt-shaped material

50

made of electrically conductive metal is subjected to a press working and the like to make a connected body

51

, in which the fuse element

5

and a pair of the terminals

2

are integrally formed, then the fuse element

5

and a pair of the terminals

2

are obtained by separation.

In order to form the connected body

51

, the material

50

is subjected to a punch working by using a mold corresponding to a shape of the fuse element

5

and the terminals

2

so as to obtain a first intermediate product

61

, which has parts

52

and

55

corresponding to the terminal

2

and the fuse element

5

, respectively. A thickness of the part

52

is the same as that of the part

55

.

Then, a part

56

corresponding to the supporting part

39

and a part

57

corresponding to the central part

40

of the part

55

of the first intermediate product

61

are subjected to rolling, forging or pressing so as to obtain a second intermediate product

62

. A thickness of the part

56

of the second intermediate product

62

is formed the same as the thickness T

1

, while a thickness of the part

57

is formed the same as the thickness T

2

.

Thereafter, the second intermediate product

62

is subjected to a punch working by using a mold corresponding to a shape of the fuse element

5

and the terminals

2

so as to obtain the terminal

2

and the fuse element

5

formed integrally with each other.

As shown

FIG. 2

, the fixing part

30

has a through hole

45

and a projection

46

. The through hole

45

penetrates through the first extended part

41

of the supporting part

39

of the fuse element

5

. The through hole

45

is formed at an end

41

a away from the end surface

8

of the first extended part

41

. The through hole

45

is formed round in its plane shape.

The projection

46

protrudes from the inner surface

17

of the body wall

14

toward the inside of the space

20

. The projection

46

protrudes from at least one inner surface

17

of the body walls

14

in a direction, in which a pair of the body walls

14

approaches with each other.

The projection

46

can engage with the through hole

45

. When the projection

46

engages with the through hole

45

, the fixing part

30

fixes the fuse element

5

and the housing

4

with each other.

As shown in

FIG. 2

, the second fixing part

31

has a mounting hole

7

and a projection

23

for positioning the terminal

2

. The mounting hole

7

penetrates through the respective terminal

2

. Each mounting hole

7

is provided at the end

3

a

of the terminal

2

. The mounting hole

7

is formed near to the center of the terminal

2

from the notched part

6

.

The projection

23

for positioning the terminal

2

protrudes from at least one inner surface

17

of the body walls

14

in a direction, in which a pair of the body walls

14

approaches with each other. Each projection

23

is provided at a position where is the vicinity of the side wall

13

a

and near to the end wall

12

b

and a position where is the vicinity of the side wall

13

b

and near to the end wall

12

b.

The projection

23

can engage with the mounting hole

7

of the terminal

2

. When the projection

23

engages with the mounting hole

7

, the second fixing part

31

fixes a pair of the terminals

2

and the housing

4

with each other.

According to the construction mentioned above, the projection

23

engages with the mounting hole

7

, the projection

46

engages with the through hole

45

, and each end

3

a

of a pair of the terminals

2

is received in the space

20

. At this time, the terminal

2

penetrates through the through hole

18

of the end wall

12

b.

The fuse assembly

1

is mounted in the electric junction box and the like. When a current value of an electric power supplied to one terminal

2

through the one receiving terminal or the like exceeds the predetermined current value, the central part

40

of fuse element

5

blows out so as to halt the power supply to the load.

As to the fuse assembly

1

according to the preferred embodiment, the thickness T

2

of the fuse element

5

at the center

44

of the central part

40

situated at the center of a pair of the terminals

2

is formed smaller than the thickness T

1

of the fuse element

5

at the first extended part

41

of the supporting parts

39

as the connection parts with the respective terminals

2

. Thus, the thickness of the fuse element

5

is formed so that the thickness gradually decreases from the first extended part

41

up to the central part

40

. Thereby, when the fuse element

5

blows out, the central part

40

securely blows out.

Therefore, a distance between the blown part of the fuse element

5

and the first extended part

41

after the blowout can be controlled and the fuse element

5

after the blowout can be prevented from vibrating due to the vibration of the vehicle in relation to the terminal

2

. Thereby, a pair of the blown ports of the fuse element

5

can be prevented from coming into contact with each other and the electric power supply to the load can be securely halted after the blowout of the fuse element

5

.

The fixing part

30

fixes the housing

40

and the fuse element

5

with each other. Therefore, the fuse element

5

can be securely prevented from vibrating due to the vibration of the vehicle in relation to the terminal

2

after the blowout of the fuse element

5

. Thereby, a pair of the blown parts can be prevented from coming into contact with each other and the electric power supply to the load can be more securely halted after the blowout of the fuse element

5

.

As to the preferred embodiment, the thickness T

2

of the fuse element

5

at the central part

40

is formed smaller than the thickness T

1

of the fuse element

5

at the supporting parts

39

with changing the thickness gradually.

However, the thickness of the fuse element

5

may be formed with gradually decreasing from the first extended part

41

up to the center

44

of the central part

40

of the fuse element

5

.

The aforementioned preferred embodiments are described to aid in understanding the present invention and variations may be made by one skilled in the art without departing from the spirit and scope of the present invention.

Number	Name	Date	Kind
4056884	Williamson et al.	Nov 1977	A
4224592	Urani et al.	Sep 1980	A
4349804	Gaia	Sep 1982	A

Fuse assembly

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