Rotary switch with rotatable contact

Information

  • Patent Grant
  • 6674183
  • Patent Number
    6,674,183
  • Date Filed
    Wednesday, July 26, 2000
    24 years ago
  • Date Issued
    Tuesday, January 6, 2004
    21 years ago
Abstract
A contact 24 is fitted to an insulator complete 25, and the contact 24 is adapted to rotate in correspondence with the operation of an operation knob. The length of an arm 38 among arm portions 37 to 39 which are provided on the contact 24 is set to be shorter than the other arm portions 37 and 39. As a result, fixed contacts 40a and 41a with which movable contacts 37a and 38a provided at distal ends of the arms 37 and 38 are brought into contact can be arranged at concentric positions, thereby making it possible to increase the number of contacts. In this case, since a relay for a small-current load is connected to the fixed contact 41a, no hindrance is caused even if the contact force of the second movable contact 38a is set to be small by devising the angles between the respective ones of the arm portions 37 to 39.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a rotary switch in which particular ones of fixed contacts are made electrically conductive in correspondence with the rotated position of a contact.




2. Description of the Related Art





FIG. 15

shows the structure of a contact of a blower switch of the type in which, for instance, a blower motor for a vehicle (max. 200-Watt level) is directly switched off. In

FIG. 15

, first to sixth terminals


2


to


7


are fitted on an insulator assembly


1


, and first to sixth fixed contacts


2




a


to


7




a


are provided on the terminals


2


to


7


at positions located at the front surface of the insulator assembly


1


. In this case, the positions of the fixed contacts


2




a


to


7




a


are set so as to be at an identical circular position.




A contact


8


, which is rotated by an operation knob (not shown), is provided on the insulator assembly


1


in contact therewith. This contact


8


has first to third arm portions


9


to


11


having identical lengths and at identical angular pitches, and the arm portions


9


to


11


are adapted to rotate in correspondence with the operation of the operation knob. First to third movable contacts


9




a


to


11




a


are respectively formed on distal ends of the first to third arm portions


9


to


11


. These movable contacts


9




a


to


11




a


are adapted to come into contact with the respective fixed contacts


2




a


to


7




a


as the center of rotation of the contact


8


is urged by a compression coil spring (not shown).





FIG. 16

shows the configuration of a circuit which is connected to the first to sixth terminals


2


to


7


. In

FIG. 16

, the first terminal


2


is connected to the cathode of a battery as the body is grounded. The second terminal


3


is connected to an ignition switch through a coil


12




a


of a relay


12


. The third terminal


4


is connected to the anode of the battery through a series circuit formed by resistors


13


to


15


, a blower motor


16


, and a contact


12




b


of the relay


12


. The fourth terminal


5


is connected to a common contact point of the resistors


13


and


14


, and the fifth terminal


6


is connected to a common contact point of the resistors


14


and


15


, and the sixth terminal


7


is directly connected to the blower motor


16


.




Accordingly, in the state in which the operation knob is at a position other than the “OFF” position, i.e., when the operation knob has been operated to an air supplying position, the relay


12


is turned on in correspondence with the operation of the ignition switch, and one end of the blower motor


16


is connected to the anode of the battery. At the same time, the other end of the blower motor


16


is connected to the cathode of the battery through the resistors


13


to


15


corresponding to the air supplying position. Consequently, a current corresponding to a resistance value flows across the blower motor


16


, and the blower motor


16


rotates in correspondence with the magnitude of the current. Therefore, it is possible to supply air to the interior of the vehicle compartment with four-step intensity corresponding to the air supplying position.




However, although there is a demand for further adding a contact to the blower switch to arrange the intensity of air supply in five steps so as to fine adjust the intensity of air supply, or for using the added contact for another function, the above-described blower switch is capable of coping with only up to four steps with the single contact because of the above-described structure of the contact. For this reason, in a case where five-step switching is required, it is necessary to use two contacts. Hence, there are drawbacks in that the structure becomes complex, and that the external size of the blower switch becomes large in size.




SUMMARY OF THE INVENTION




The invention has been devised in view of the above-described circumstances, and its object is to provide a rotary switch which is capable of increasing the number of contacts without enlarging the external shape while using a single contact.




In accordance with the invention, there is provided a rotary switch comprising: an insulator provided with a plurality of terminals respectively having fixed contacts; a contact having a plurality of arm portions, movable contacts respectively provided on distal ends of the arm portions being respectively adapted to slide on the fixed contacts as the contact rotates; and urging means for imparting contact forces with respect to the fixed contacts to the movable contacts by urging a center of rotation of the contact, particular ones of the fixed contacts being made electrically conductive in correspondence with a rotated position of the contact, wherein a particular one of the arm portions in the contact is set to be short, and angles between respective ones of the arm portions are set such that the contact forces of the movable contacts with respect to the fixed contacts assume magnitudes corresponding to a load connected to the fixed contacts.




In accordance with the above-described arrangement, when the contact rotates, the movable contacts provided on the distal ends of the arm portions of the contact slide on the fixed contacts, so that particular ones of fixed contacts are made electrically conductive through the contact. At this time, since a particular one of the arm portions in the contact is set to be short, the fixed contacts where the movable contacts are brought into contact can be arranged at concentric positions. Hence, it becomes possible to increase the number of contacts without enlarging the external shape. In this case, since angles between respective ones of the arm portions are set such that the contact forces of the movable contacts with respect to the fixed contacts assume magnitudes corresponding to a load connected to the fixed contacts, no drawback occurs to the energization of the contacts although the contact forces of the movable contacts with respect to the fixed contacts are nonuniform due to the varying lengths of the arm portions.




In the above-described arrangement, an arrangement may be provided such that the fixed contact with which the movable contact with a large contact force is brought into contact is connected to a large-current load, while the fixed contact with which the movable contact with a small contact force is brought into contact is connected to an energizing means for energizing the large-current load.




In accordance with the above-described arrangement, since the fixed contact with which the movable contact with a small contact force is brought into contact is connected to an energizing means for energizing the large-current load which is connected to the fixed contact with which the movable contact with a large contact force is brought into contact, the current flowing across the movable contact with a small contact force and the fixed contact is small. Hence, no drawback occurs to the energization of the contacts even if the contact force of the movable contact with respect to the fixed contact is small.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a plan view of an insulator assembly shown in a state in which a contact is fitted in accordance with an embodiment of the invention;





FIG. 2

is a perspective view of a blower switch;





FIG. 3

is an exploded perspective of the blower switch;





FIG. 4

is a front elevational view of an operation knob assembly;





FIG. 5

is a rear view of the operation knob assembly;





FIG. 6

is a front elevational view of a contact;





FIG. 7

is a rear view of the contact;





FIG. 8

is a front elevational view of the insulator assembly;





FIG. 9

is a rear view of the insulator assembly;





FIG. 10

is a circuit diagram illustrating the relationship of connection in the blower switch;





FIG. 11

is a cross-sectional view of essential portions illustrating a state in which a compression coil spring is fitted;





FIG. 12

is a front elevational view of the contact illustrating the positional relationship between the contact center of gravity of the contact and the center of rotation;





FIG. 13

is a front elevational view illustrating the positional relationship;





FIG. 14

is a front elevational view of the insulator assembly illustrating a state in which the contact has been rotated by one step;





FIG. 15

is a diagram illustrating a conventional example and corresponding to

FIG. 1

; and





FIG. 16

is a diagram corresponding to FIG.


10


.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring now to

FIGS. 1

to


14


, a description will be given of an embodiment in which the invention is applied to a blower switch for a vehicle.





FIG. 2

is a perspective view of the blower switch, and

FIG. 3

is an exploded perspective view of the blower switch. In

FIGS. 2 and 3

, a blower switch (corresponding to a rotary switch)


21


includes an operation knob assembly


22


, a compression coil spring


23


, a contact


24


, and an insulator assembly


25


.





FIG. 4

is a front view of the operation knob assembly


22


, and

FIG. 5

is a rear view thereof. In

FIGS. 4 and 5

, the operation knob assembly


22


is provided with an operation knob


26


. As the operating positions of the operation knob


26


, an “OFF” position is set, and an air supplying position “


1


,” an air supplying position “


2


,” an air supplying position “


13


,” an air supplying position “


4


,” and an air supplying position “


5


” are respectively set at each predetermined angle (22.5°) in correspondence with the intensity of air flow.




This operation knob assembly


22


is for transmitting the rotational operation of the operation knob


26


to the contact


24


, and the operation knob


26


is adapted to click at the “OFF” position and each air supplying position at each predetermined angle (22.5°) by an clicking mechanism (not shown). An annular skirt portion


27


is formed on the rear surface of the operation knob assembly


22


, and the insulator assembly


25


is adapted to be fitted to the skirt portion


27


(see FIG.


11


). A rotor


28


formed integrally with the operation knob


26


is provided within the skirt portion


27


, and the rotor


28


is adapted to rotate as the operation knob


26


is rotated. A hollow cylindrical portion


29


(see

FIG. 11

) is formed projectingly at the center of the rotor


28


, and the contact


24


is fitted to the hollow cylindrical portion


29


(see FIG.


11


). Further, a recessed portion


30


is formed in the rotor


28


.




A pair of attaching portions


31


are integrally provided on the operation knob assembly


22


, and a positioning hole


32


and a screw inserting hole


33


are formed in each of the attaching portions


31


. In this case, the blower switch


21


can be fixed at a portion subject to attachment by threadedly engaging screws in the screw inserting holes


33


in the state in which projections formed on the portion subject to attachment are inserted in the positioning holes


32


.




In addition, a lamp insertion hole


34


is formed in the rear surface of the operation knob assembly


22


, and as a lamp


35


(see

FIG. 3

) inserted in the lamp insertion hole


34


emits light, the figure of a fan and each numeral provided on the front surface of the operation knob assembly


22


are lit up.





FIG. 6

is a front view of the contact


24


, and

FIG. 7

is a rear view thereof. In

FIGS. 6 and 7

, a hollow cylindrical portion


36


is formed projectingly at the center of the contact


24


, and the hollow cylindrical portion


36


is fitted over an outer periphery of the hollow cylindrical portion


29


formed on the rotor


28


of the operation knob assembly


22


. In this case, the iii


23


is interposed between the insulator assembly


25


and the contact


24


(see FIG.


11


). An engaging projection


24




a


is formed on the contact


24


, and as the engaging projection


24




a


is retained at the recessed portion


30


formed in the rotor


28


, the rotational operation of the operation knob


26


is transmitted to the rotor


28


.




The contact


24


is formed with first to third arm portions


37


to


39


. First to third movable contacts


37




a


to


39




a


are respectively formed on distal ends of these first to third arm portions


37


to


39


, and these movable contacts


37




a


to


39




a


are adapted to slide on the insulator assembly


25


.




Here, the length of the first arm portion


37


is set to be shorter than the length of the second and third arm portions


38


and


39


, and the angle between the first and second arm portions


37


and


38


is set to be small. By virtue of such an arrangement, in the contact


24


, the contact forces of the first and third movable contacts


37




a


and


39




a


are set to be substantially identical, and the contact force of the second movable contact


38




a


is set to be smaller than the contact forces of the first and third movable contacts


37




a


and


39




a.







FIG. 8

is a front view of the insulator assembly


25


, and

FIG. 9

is a rear view thereof. In

FIGS. 8 and 9

, first to seventh terminals


40


to


46


are fitted to the insulator assembly


25


, and first to seventh fixed contacts


40




a


to


46




a


are respectively provided on these terminals


40


to


46


at positions located at the front surface of the insulator assembly


25


. In this case, the first and second fixed contacts


40




a


and


41




a


are formed in semi-annular shapes, and the first fixed contact


40




a


is provided on the inner side of the second fixed contact


41




a


. Namely, the first and second fixed contacts


40




a


and


41




a


are provided at concentric positions such that their portions angularly overlap with each other.




In addition, land portions


48


to


50


, which are flush with the first to third terminals


40


to


42


, are formed on the insulator assembly


25


in correspondence with these terminals


40


to


42


.




A connector


47


is provided on the rear surface of the insulator assembly


25


. This connector


47


is provided with terminals


51


and


52


for turning on the lamp


35


in addition to the aforementioned terminals


40


to


46


.





FIG. 1

shows the positional relationship between the contact


24


and the insulator assembly


25


. In this case, the position of the contact


24


is shown in the state in which the operation knob


26


has been operated to the “OFF” position. In

FIG. 1

, the first movable contact


37




a


of the contact


24


is located on the first land portion


48


adjacent to the first fixed contact


40




a


, the second movable contact


38




a


is located on the second land portion


49


adjacent to the second fixed contact


41




a


, and the third movable contact


39




a


is located on the third land portion


50


adjacent to the third fixed contact


42




a.







FIG. 10

shows the configuration of a circuit connected to the first to seventh terminals


40


to


46


. In

FIG. 10

, the first terminal


40


is connected to the cathode of a battery as the body is grounded. The second terminal


41


is connected to an ignition switch through a coil


53




a


of a relay (corresponding to an energizing means)


53


. The third terminal


42


is connected to the anode of the battery through a series circuit formed by resistors


54


to


57


, a blower motor (max. 200-Watt level)


58


, and a contact


53




b


of the relay


53


. The fourth terminal


43


is connected to a common contact point of the resistors


54


and


55


, the fifth terminal


44


is connected to a common contact point of the resistors


55


and


56


, and the sixth terminal


45


is connected to a common contact point of the resistors


56


and


57


. The seventh terminal


46


is directly connected to the blower motor


58


.




By virtue of the above-described configuration, in the state in which the operation knob


26


of the blower switch


21


is at a position other than the “OFF” position, i.e., when the operation knob


26


has been operated to an air supplying position, the relay


53


is turned on in correspondence with the operation of the ignition switch, and one end of the blower motor


58


is connected to the anode of the battery. At the same time, the other end of the blower motor


58


is connected to the cathode of the battery through the resistors


54


to


57


corresponding to the air supplying position. Consequently, a current corresponding to a resistance value flows across the blower motor


58


, and the blower motor


58


rotates in correspondence with the magnitude of the current. Therefore, it is possible to supply air to the interior of the vehicle compartment with five-step intensity corresponding to the air supplying position.




Here, since the distances of the movable contacts of the contact


24


from the center of rotation (the center of urging by the compression coil spring


23


) are different, the contact forces with respect to the insulator assembly


25


are different. Hereafter, a description will be given of the contact forces of the movable contacts


37




a


to


39




a.







FIG. 11

shows the cross section of principal portions of the operation knob assembly


22


. In

FIG. 11

, the attachment length x of the compression coil spring


23


is a value in which the thicknesswise dimension C of the terminal, the dimension D from the contact position of the contact


24


with respect to the terminal to the contact position thereof with respect to the compression coil spring


23


, and the dimension E from the fitting surface of the rotor


28


to the contact surface thereof with respect to the compression coil spring


23


are subtracted from a value obtained by adding together the dimension A from the fitting surface of the rotor


28


to an end surface of the rotor


28


and the dimension B from the end surface of the rotor


28


to the terminal fitting surface of the insulator assembly


25


. Namely, the attachment length x of the compression coil spring


23


can be determined as









x
=

A
+
B
-
C
-
D
-
E







=

10.5
+
3
-
0.8
-
1.8
-
4.9







=
6













Next, the contact force Fs of the total contacts is a value in which the attaching load w is added to a value in which a value obtained by subtracting the attachment length x from the natural length I of the compression coil spring


23


is multiplied by the spring constant k. Namely,









Fs
=



(

1
-
X

)

·
k

+
w







=



(

6
-
6

)

·
0.5

+
1.25







=

1.25






(
kgf
)















In other words, since the attachment length x of the compression coil spring


23


is designed so as to be the natural length l, the contact force Fs of the contacts is ideally constituted by the attachment load w alone.




Incidentally, the contact force of a predetermined movable contact can be determined by multiplying by the attachment load w the ratio of the area of a triangle formed by connecting two movable contacts a other than the predetermined movable contact and the center of rotation of the contact


24


to the area of a triangle formed by connecting the three movable contacts


37




a


to


39




a.






It should be noted that since the conventional contact center of gravity agrees with the center of rotation (the urging center), the contact forces of the movable agree with each other. Further, the contact center of gravity in this embodiment (the position where the areas of the three triangles agree with each other) is offset from the center of rotation (the urging center), as shown in FIG.


12


. In a case where the contact center of gravity and the urging center agree with each other, although the contact forces of the movable contacts


37




a


to


39




a


agree with each other, the contact forces of the movable contacts


37




a


to


39




a


vary in correspondence with the portion of offset from the contact center of gravity. In this embodiment, it is expected that the contact force of the second movable contact


38




a


located on the side opposite to the direction offset from the contact center of gravity declines, whereas the contact forces of the first and third movable contacts


37




a


and


39




a


located on the same side as the direction offset from the contact center of gravity.




Accordingly, the areas of the triangles formed by connecting the center of rotation and the two movable contacts of the movable contacts


37




a


to


39




a


in the contact


24


, as shown in

FIG. 13

, are respectively determined. In this case, since the area of a triangle can be obtained by the length of the base×height/2, the area J of a first triangle (indicated by A in

FIG. 13

) formed by connecting the center of the second movable contact


38




a


, the center of the third movable contact


39




a


, and the center of rotation of the contact


24


can be determined as









J
=


(


(

G
+
H

)

/
2

)

×

(


(

G
+
K

)

/
2

)

×
sin






I
÷
2








=


(


(

18
+
14

)

/
2

)

×

(


(

18
+
16

)

/
2

)

×
sin





47.5

°







=
100.27













Further, the area N of a second triangle (indicated by B in

FIG. 13

) formed by connecting the center of the first movable contact


37




a


, the center of the third movable contact


39




a


, and the center of rotation of the contact


24


can be determined as









N
=


(


(

G
+
H

)

/
2

)

×

(


(

H
-
0

)

/
2

)

×
sin







(

M
-
1

)

÷
2








=


(


(

18
+
14

)

/
2

)

×

(


(

14
+
12

)

/
2

)

×

sin


(


75

°

-

47.5

°


)









=
48.2













Further, the area Q of a third triangle (indicated by C in

FIG. 13

) formed by connecting the center of the first movable contact


37




a


, the center of the second movable contact


38




a


, and the center of rotation of the contact


24


can be determined as









Q
=


(


(

H
+
0

)

/
2

)

×

(


(

G
+
K

)

/
2

)

×
sin






M
÷
2








=


(


(

14
+
12

)

/
2

)

×

(


(

18
+
16

)

/
2

)

×
sin





75


°
÷
2








=
106.74













Hereafter, the contact forces of the respective movable contacts


37




a


to


39




a


are determined.









R
=

Fs
×

(

J
/

(

J
+
N
+
Q

)


)








=

1.25
×

100.27
/

(

100.27
+
48.02
+
106.74

)









=

0.49


(
kgf
)








=

4.82


(
N
)















Further, the contact force S of the second movable


38




a


can be determined as









S
=

Fs
×

(

N
/

(

J
+
N
+
Q

)


)








=

1.25
×

48
/

(

100.27
+
48.02
+
106.74

)









=

0.24


(
kgf
)








=

2.31


(
N
)















Further, the contact force T of the third movable


39




a


can be determined as









T
=

Fs
×

(

Q
/

(

J
+
N
+
Q

)


)








=

1.25
×

106.74
/

(

100.27
+
48.02
+
106.74

)









=

0.52


(
kgf
)








=

5.13


(
N
)















Accordingly, the ratio among the contact force of the first movable contact


37




a


, the contact force of the second movable contact


38




a


, and the contact force of the third movable contact


39




a


becomes 1:2.1:2.2. Namely, in the contact


24


, although the second arm portion


38


and the third arm portion


39


have substantially identical lengths, the contact force of the second movable contact


38




a


provided on the second arm portion


38


is one-half of the contact force of the third movable contact


39




a


provided on the third arm portion


39


. Further, although the first arm portion


37


is shorter than the third arm portion


39


, the contact force of the first movable contact


37




a


provided on the first arm portion


37


and the contact force of the second movable contact


38




a


provided on the second arm portion


38


are substantially identical.




Next, a description will be given of the operation of the above-described arrangement.




If the operation knob


26


of the blower switch


21


is operated from the “OFF” position to the air supplying position “


1


”, the contact


24


rotates to the position shown in

FIG. 14

in conjunction with the rotation of the operation knob


26


. Namely, the first movable contact


37




a


leaves the first land portion


48


and moves onto the first fixed contact


40




a


, the second movable contact


38




a


leaves the second land portion


49


and moves onto the second fixed contact


41




a


, and the third movable contact


39




a


leaves the third land portion


50


and moves onto the third fixed contact


42




a


. Consequently, as shown in

FIG. 10

, the first terminal


40


and the second terminal


41


, the third terminal


42


are made electrically conductive through the contact


24


.




Here, if the ignition switch is turned on, the coil


53




a


of the relay


53


is energized, so that the contact


53




b


of the relay


53


is turned on. As a result, since the current flows across the blower motor


58


through the resistors


54


to


57


, air is supplied to the interior of the vehicle compartment in correspondence with the rotation of the blower motor


58


. In this case, since the current flowing across the blower motor


58


is smallest, the number of revolution of the blower motor


58


is small, and the intensity of air supply to the interior of the vehicle compartment is smallest.




Next, if the operation knob


26


is operated to the air supplying position “


2


” to increase the rate of air supply to the interior of the vehicle compartment, the contact


24


rotates further, and the third movable contact


39




a


is located at the second fixed contact


41




a


. At this time, since the state of energization between the first terminal


40


and the second terminal


41


is maintained, the on state of the contact


53




b


of the relay


53


is maintained, so that the blower motor


58


is energized through the resistors


55


to


57


. As a result, the energizing current flowing across the blower motor


58


increases, so that the number of revolution of the blower motor


58


increases, and the rate of air supply to the interior of the vehicle compartment increases correspondingly.




Similarly, by operating the operation knob to the air supplying position “


3


,” to the air supplying position “


4


,” and to the air supplying position “


5


,” it is possible to increase the rate of air supply to the interior of the vehicle compartment in steps.




Incidentally, since the blower switch


21


is connected so as to directly switch off a large energizing current flowing across the blower motor


58


, it is necessary to set a large contact force for the movable contact where the energizing current to the blower motor


58


flows. Nevertheless, if attention is focused on the second movable contact


38




a


, which is connected to the coil


53




a


of the relay


53


through the second fixed contact


41




a


, its energizing current is smaller than the energizing current to the blower motor


58


. Therefore, no hindrance is caused even if the contact force of the second movable contact


38




a


is set to be smaller than the contact forces of the first and third movable contacts


37




a


and


39




a.






In accordance with the above-described embodiment, since the length of the second arm portion


38


in the contact


24


is formed to be shorter than the other arm portions


37


and


39


, the first and second fixed contacts


40




a


and


41




a


where the first and second movable contacts


37




a


and


38




a


are brought into contact can be provided at concentric positions. Accordingly, unlike the conventional example in which the first to third arm portions in the contact are formed with identical lengths, the intensity of air supply can be arranged with five-step switching by adding a fixed contact without enlarging the blower switch


21


.




In this case, the angles between respective ones of the arm portions


37


to


39


in the contact


24


are set such that the contact forces of the movable contacts


37




a


to


39




a


with respect to the fixed contacts


40




a


to


46




a


assume magnitudes corresponding to the relay


53


connected to the relevant fixed contacts


40




a


to


46




a


or the blower motor


58


. Therefore, no hindrance is caused to the energization for each load even if the contact forces of the movable contacts


37




a


to


39




a


differ by setting the length of the first arm portion


37


among the arm portions


37


to


39


of the contact


24


to be short, as described above.




The invention should not be limited to the above-described embodiment, and can be modified or expanded as shown below.




The intensity of air supply is not limited to five steps, and maybe arranged in six steps or more.




The blower motor


58


may be energized through a power transistor instead of the relay


53


.




A blower motor for an air conditioner for a rear seat may be connected to the fixed contact added in the blower switch


21


, and the blower motor for an air conditioner for a rear seat may be controlled by the operation of the blower switch


21


.




The circuit which is connected to the fixed contacts where the movable contacts with small contact forces are brought into contact is not limited to the coil of the relay, and in a case where a plurality of motors are directly switched off by the rotary switch, motors with small energizing currents may be directly switched off.




The invention is applicable not only to the blower switch but also to various other switches.




As is apparent from the foregoing description, in accordance with the rotary switch of the invention, a particular one of the arm portions in the contact is set to be short, and angles between respective ones of the arm portions are set such that the contact forces of the movable contacts with respect to the fixed contacts assume magnitudes corresponding to a load connected to the fixed contacts. Accordingly, an outstanding advantage can be offered in that the fixed contacts can be provided at concentric positions, and the number of contacts can be increased without enlarging the external shape while using a single contact.



Claims
  • 1. A rotary switch comprising:an insulator provided with a plurality of terminals respectively having first contacts that are fixed contacts; a second contact having a plurality of arm portions, said arm portions having movable contacts respectively on distal ends thereof, said movable contacts slide on said fixed contacts, respectively in response to rotation of said second contact; and means for imparting contact forces with respect to said fixed contacts to said movable contacts by urging a center of rotation of said second contact, said fixed contacts to be selected made electrically conductive in correspondence with a rotated position of said second contact, wherein at least one said arm portion in said second contact is short as compared with the other, and angles defined between respective ones of said arm portions are set such that the contact forces of said movable contacts with respect to said fixed contacts correspond in magnitudes to a load connected to said fixed contacts.
  • 2. The rotary switch according to claim 1, wherein said fixed contact is brought into contact with said movable contact with a large contact force and is connected to a large-current load, and further comprising:energizing means for energizing the large-current load, said fixed contact is brought into contact with said movable contact with a small contact force and is connected to the energizing means.
  • 3. The rotary switch according to claim 2, wherein said energizing means is a relay.
  • 4. A rotary switch comprising:an insulator with a plurality of terminals, each terminal including a fixed contact; and a rotatable contact having a center of rotation and a plurality of arm portions, each arm portion including a movable contact that slides on a fixed contact in response to a rotation of the rotatable contact; wherein one of said arm portions is shorter than the other arm portions when measured from the center of rotation to the movable contact of said shorter arm portion.
  • 5. The rotary switch according to claim 4, wherein when said movable contact slides over said fixed contact said fixed contact conducts electricity.
  • 6. The rotary switch according to claim 5, wherein said fixed contacts conduct electricity in response to a rotation of the said rotatable contact.
  • 7. The rotary switch according to claim 6, wherein said arm portions include a proximal end and a distal end and said movable contacts are provided on the distal ends of said arm portions.
  • 8. The rotary switch according to claim 6, wherein the movable contacts are connected to energizing means.
  • 9. The rotary switch according to claim 6, comprising first, second and third arm portions where the angle between the first and second arm portions is smaller than the angle between the second and third arm portion and said shorter arm portion is the first arm portion.
  • 10. The rotary switch according to claim 6, wherein the rotatable contact includes a center of gravity that is offset from the center of rotation.
  • 11. The rotary switch according to claim 9, comprising first, second and third contact forces corresponding to the first, second and third arm portions respectively and the contact forces correspond to a current load that flows through said fixed contacts when said movable contacts slide on said fixed contacts.
  • 12. The rotary switch according to claim 11, wherein the first contact force is substantially identical to the third contact force.
  • 13. The rotary switch according to claim 11, wherein the ratio of contact forces between the second, first, and third contact forces is 1:2.1:2.2.
  • 14. The rotary switch according to claim 10, wherein said movable contacts have a contact force and the contact force of each movable contact varies in correspondence with the offset dimension between the center of gravity and the center of rotation.
  • 15. A rotary switch comprising:an insulator including a plurality of terminals, wherein said terminals each includes fixed contacts; a second contact including a plurality of arm portions, wherein said arm portions each has a distal end with a movable contact; said movable contacts slide over said fixed contacts in response to a rotation of said second contact; and one of said arm portions in said second contact is shorter than the other arm portions.
Priority Claims (1)
Number Date Country Kind
11-210611 Jul 1999 JP
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Number Name Date Kind
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4586011 Mostosi Apr 1986 A
4748297 Sorenson et al. May 1988 A
4876416 Frantz et al. Oct 1989 A
4945195 Ipcinski Jul 1990 A
5161422 Suman et al. Nov 1992 A
5287005 Shinkawa Feb 1994 A
5691612 Corey Nov 1997 A
6222139 Pandit et al. Apr 2001 B1
6239679 Comtois et al. May 2001 B1
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6399905 Nishikawa et al. Jun 2002 B1
Foreign Referenced Citations (1)
Number Date Country
443 698 May 1997 DE