US3887779A - Switch - Google Patents

Abstract

A switch of the single-pole, single-throw type, single-pole, double-throw type, double-pole, single-throw type or double-pole, double-throw type which is mainly mounted on and used with a variable resistor or the like. The switch can operate with great reliability, and particularly when the switch is used to disconnect a circuit where a large inrush current is generated, it can prevent the deterioration of the voltage proof due to the abraded powder caused by arc.

Description

United States Patent [191 Tanaka et a1.

SWITCH Inventors:

Assignee:

Filed:

Appl. No.:

Heiroku Tanaka; Yoshinobu Nakagawa, both of Neyagawa, Japan Matsushita Electric Industrial Co., Ltd., Osaka, Japan Aug. 27, 1973 Foreign Application Priority Data Aug. 29, 1972 Japan 47-101102 U.S. C1..... Int. Cl.

200/153 L; 200/67 C; 200/144 R H01h 3/42 Field of Search. 200/67 C, 153 L, 253, 144 R;

References Cited UNITED STATES PATENTS Schaefer 200/67 C 1 June 3, 1975 3,031,552 4/1962 Stewart 200/144 R 3,417,214 12/1968 Krehbiel 200/67 C FOREIGN PATENTS OR APPLICATIONS 558,834 7/1957 Belgium 174/137 R 949,321 2/1963 United Kingdom 200/67 C Primary ExaminerDavid Smith, Jr.

Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [57] 7 ABSTRACT A switch of the single-pole, single-throw type, singlepole, double-throw type, double-pole, single-throw type or double-pole, double-throw type which is mainly mounted on and used with a variable resistor or the like. The switch can operate with great reliability, and particularly when the switch is used to disconnect a circuit Where a large inrush current is generated, it can prevent the deterioration of the voltage proof due to the abraded powder caused by arc.

3 Claims, 5 Drawing Figures PATENTEUJUM I975 SHEET FIG.

FIG. 2

1 SWITCH The present invention is an improvement invention of the invention having the same title as the present invention and disclosed in the United States Patent Application Ser. No. 195438, filed Nov. 3, 1971, now abandoned, and the Canadian Patent Application Ser. No. 126773, filed Nov. 3, 1971.

The present invention relates to a switch which is mainly mounted on and used with a variable resistor or the like.

It is the object of the present invention to provide a switch which operates with greater reliability.

The switch according to the present invention has among its great advantages the fact that a driving plate for actuating a movable contact piece adapted to engage and disengage fixed contacts is carried on mounting projections located in the vicinity of the fixed contacts and each of the mounting projections is formed with a groove for preventing the deterioration of the voltage proof, whereby even when the tiny particlesworn off due to the opening and closing of the switch are deposited on the lower side of the driving plate, the deterioration of the voltage proof between the fixed contacts which may be caused through the abraded powder can be prevented. Further great advantage of the switch of this invention is that it is simple in construction, inexpensive to manufacture and capable of handling large current.

Other objects, features and advantages will become readily apparent from considering the following detailed description taken in conjunction with the accompanying drawings, in which:

. FIG. 1 is a side view showing a switch according to an embodiment of the present invention which is combined with a variable resistor;

FIG. 2 is an enlarged sectional view of FIG. 1;

FIG. 3 is a top view of the switch casing constituting a part of the switch shown in FIG. 1;

FIG. 4 is a top view showing the inside of the switch cover constituting a part of the switch of FIG. 1; and

FIG. 5 is a top view showing the resistor cover member constituting a part of the switch shown in FIG. 1.

An exemplary embodiment of the present invention will now be described with reference to the accompanying drawings in which the present invention is shown embodied in a single-pole, double-throw switch used in association with a variable resistor.

Referring first to FIG. 1, numeral 1 designates a variable resistor unit including a bearing 3 in which an operating rotary shaft 2 is mounted to extend therethrough, a mounting base plate 4 on which the bearing 3 is mounted, a resistor 5 disposed on the mounting base plate 4 and a metal resistor cover 6 attached to the mounting base plate 4. Disposed within the cover 6 is a brush assembly (not shown) attached to the operating rotary shaft 2 and having secured thereon a brush (not shown) which slides on the resistor 5 in accordance with the rotation of the shaft 2. Numeral 7 designates an improved switch unit according to the present invention, which is mounted on the bottom side of the resistor cover 6 and which is turned on and off in accordance with the rotation of the operating rotary shaft 2.

The construction of the switch unit 7 will be described in detail with reference to FIGS. 2 to 5. In the drawings, numeral 8 designates a cylindrical switch casing made of a noninflammable insulating material,

which is provided with a vertical wall 9 integrally formed all around the peripheral edge thereof to project upwardly. The vertical wall 9 serves to prevent the deterioration of the voltage proof between current carrying portions and a metal switch cover 25 which will be described later. Fixed contacts 10 and 10' integral with external terminals are disposed in two places on the switch casing 8. Numeral l1 designates a movable contact piece which is disposed on the switch casing 8 to engage and disengage with the fixed contacts 10 and 10'. The contact piece 11 is electrically connected to an external terminal 12 and rotatably mounted on a supporting post 13 connected to the external terminal 12, and projections 14 and 14' are provided on both sides of that end of the contact piece 11 which is opposite to the end mounted on the supporting post 13.

Numeral 15 designates a narrow groove formed in the switch casing 8 and this groove 15 is provided in such a manner as to provide a partition between the fixed contacts 10 and 10 as well as between the fixed contacts 10 and 10 and the supporting post 13, thereby preventing the deterioration of the voltage proof through abraded powder produced by the opening and closing of the switch. Numeral 16 designates a step projection integrally formed with the vertical wall 9 of the switch casing 8 to inwardly project therefrom, and a locating hole 17 is formed in the step projection 16. Numerals l8 and 18' designate mounting projections provided near the fixed contacts 10 and 10 and formed with grooves 19 and 19, respectively. Numeral 20 designates a driving plate made of an insulating material and mounted on the step projection 16 and the mounting projections 18 and 18'. The driving plate 20 is provided at one end thereof with a locating hole 21 positioned above the locating hole 17, and an engaging projection 36 formed on the lower surface of the driving plate 20 is placed between the projections 14 and 14 on both sides of the movable contact piece 11 to engage therewith with a slight clearance therebetween. The driving plate 20 is mounted on the step projection 16 and the mounting projections 18 and 18 so that it is positioned horizontally. Numeral 22 designates a cam member made of a metallic material having a positioning projection 23 formed on the lower side thereof to project through the locating hole 21 formed in the driving plate 20 and then fitted in the locating hole 17 formed in the projection 16 of the switch casing 8. The cam member 22 is also provided with a positioning projection 24 formed on the upper side thereof to be located on the same axis with the positioning projection 23 and the positioning projection 24 is located in positioning holes 26 and 27 respectively formed in the bottom of a metal switch cover 25 and the bottom of the resistor cover 6 attached to the bottom of the switch cover 25. The cam member 22 is also provided with engaging arms 28 and 28' which are spaced apart from each other and the engaging arms 28 and 28' extend into cam guide slots 29 and 30 formed respectively in the switch cover 25 and the resistor cover 6. Numeral 31 designates a spring extended between a holding means 32 formed on the driving plate 20 and a holding means 33 formed in one end of the cam member 22 and the spring 31 acts to separate the driving plate 20 and the cam member 22 from each other. The switch cover 25 is opened only on the lower side thereof and it holds the switch casing 8 in place by means of a plurality of holding legs which are folded to securely hold the switch casing 8. A cam actuating means 35 formed on the operating rotary shaft 2 engages between the engaging arms 28 and 28', t

The operation of the switch described above will no be explained. When the operating rotary shaft 2 is rotated, by virtue of the fact that the cam actuating means 35 is positioned between the engaging arms 28 and 28 of the cam member 22, the cam member 22 is rotated in accordance with the rotation of the operating rotary shaft 2 with its projection 24 acting as a pivot. Consequently, the rotation of the cam member 22 causes the driving plate 20 to move in a direction opposite to that of the movement of the former owing to the action of the spring 31 provided between the cam member 22 and the driving plate 20. In this case, since the engaging projection 36 formed on the lower side of the driving plate 20 is placed between the side projections 14 and 14' of the movable contact piece 11 to engage therewith, the movable contact piece 11 engages and disengages the fixed contacts and 10' in accordance with the movement of the driving plate 20. In other words, the switch operates as a single-pole, double-throw switch.

Since the wearing off of fine particles occurs during these operations due to arcing between contacts, the deterioration of the voltage proof between the current carrying portions and the switch cover 25 is prevented by means of the vertical wall 9, while the deterioration of the voltage proof between the fixed contacts 10 and 10 and between the fixed contacts 10 and 10 and the supporting post 13 is prevented by means of the groove 15. The use of these means has been proposed by the inventor. A unique feature of the improved switch of this invention is that in addition to the vertical wall 9 and the groove 15, the mounting projections 18 and 18 for carrying the driving plate are provided respectively with the grooves 19 and. 19'. The reason is that the abraded powder produced during the opening and closing of the switch deposit on the lower side of the driving plate 20 and there is thus the danger of causing a deterioration in the voltage proof between the fixed contacts 10 and 10' due to the abraded powder deposited on the lower side of the driving plate 20 and the abraded powder deposited on the sides and the bottom of the switch casing 8. Accordingly, the provision of the grooves 19 and 19' in the mounting projections for carrying the driving plate 20 prevents-deterioration of the voltage proof between the fixed contacts 10 and 10'.

In addition to the above descriptions, the mounting projections 18 and 18' act as stabilizers of the driving plate 20. Since the driving plate 20 and the cam memher 22 are always urged in opposite directions by force of the spring 31, the driving plate 20 tends to incline against the bottom surface of the switch casing 8.

Usually, the inclination of the driving plate 20 is pivotably held by positioning projection 23 of the cam member 22, however, it is not sufficient to maintain the driving plate 20 in parallel with the bottom surface of the switch casing 8.

While, in the embodiment of the present invention so far described, the present invention has been described as embodied in a single-pole, double-throw switch, it is apparent that the present invention can also be applied to a single-pole, single-throw switch or double-pole type switch. Further, instead of placing the engaging projection 36 of the driving plate 20 between the projections 14 and 14 on both sides of the movable contact piece 11 in engagement therewith, the movable contact piece 11 may be provided with an engaging hole in which is engaged the engaging projection 36 of the movable contact piece 11.

What we claim is:

1. A switch comprising a switch casing made of an insulating material, at least two fixed contacts arranged on said switch casing, a movable contact piece pivotably mounted on a supporting post on said switch casing to engage and disengage with said fixed contacts, at least two mounting projections disposed on said switch casing in the vicinity of said fixed contacts, each of said mounting projections being formed with a first groove for preventing the deterioration of voltage proof, a driving plate mounted on a step projection formed on said switch casing and an engaging projection formed on the lower surface of said driving plate, said engaging projection being connected to change the position of said movable contact piece, and a spring provided between a cam member for effecting a switching operation of said driving plate and said driving plate to separate said cam member and said driving plate from each other.

2. A switch according to claim 1, wherein said switch casing is provided with a second groove to separate said fixed contacts from other current carrying portions of said switch, said second groove preventing the deterioration of voltage proof.

3. A switch according to claim 1, wherein said switch casing is formed with a second groove for separating said fixed contacts from other current carrying portions of said switch, and a vertical wall provided on the whole circumferential edgeof said switch casing, said second groove and said wall preventing the deterioration of voltage proof.

Claims (3)

1. A switch comprising a switch casing made of an insulating material, at least two fixed contacts aRranged on said switch casing, a movable contact piece pivotably mounted on a supporting post on said switch casing to engage and disengage with said fixed contacts, at least two mounting projections disposed on said switch casing in the vicinity of said fixed contacts, each of said mounting projections being formed with a first groove for preventing the deterioration of voltage proof, a driving plate mounted on a step projection formed on said switch casing and an engaging projection formed on the lower surface of said driving plate, said engaging projection being connected to change the position of said movable contact piece, and a spring provided between a cam member for effecting a switching operation of said driving plate and said driving plate to separate said cam member and said driving plate from each other.

1. A switch comprising a switch casing made of an insulating material, at least two fixed contacts aRranged on said switch casing, a movable contact piece pivotably mounted on a supporting post on said switch casing to engage and disengage with said fixed contacts, at least two mounting projections disposed on said switch casing in the vicinity of said fixed contacts, each of said mounting projections being formed with a first groove for preventing the deterioration of voltage proof, a driving plate mounted on a step projection formed on said switch casing and an engaging projection formed on the lower surface of said driving plate, said engaging projection being connected to change the position of said movable contact piece, and a spring provided between a cam member for effecting a switching operation of said driving plate and said driving plate to separate said cam member and said driving plate from each other.

2. A switch according to claim 1, wherein said switch casing is provided with a second groove to separate said fixed contacts from other current carrying portions of said switch, said second groove preventing the deterioration of voltage proof.

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