Patent Description:
A known electrical switch comprises a frame, and a bridge member movable in a depth direction relative to the frame between a first bridge position and a second bridge position by rotation of the operating shaft, wherein the first bridge position corresponds to a connected state of the electrical switch, and the second bridge position corresponds to a disconnected state of the electrical switch.

One of the problems associated with the above known electrical switch is that a first opening force which the operating shaft is adapted to exert to the bridge member during an opening event of the electrical switch is offset relative to a centre of mass of the bridge member, and therefore the first opening force incurs rotation or tilting of the bridge member during the opening event.

An example of a known electrical switch is described in publication <CIT>.

An object of the present invention is to provide an electrical switch so as to solve the above problem. The objects of the invention are achieved by an electrical switch which is characterized by what is stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims.

The invention is based on the idea of providing the electrical switch with an anti-tilting member movable in a lateral direction relative to the frame between a first position and a second position by rotation of the operating shaft, wherein the anti-tilting member is adapted to exert a second opening force to the bridge member during the opening event, the second opening force being adapted to provide an anti-tilting torque for cancelling at least partially a tilting torque provided by the first opening force to the bridge member.

An advantage of the electrical switch of the invention is that tilting of the bridge member during the opening event is eliminated or at least substantially reduced.

<FIG> shows an electrical switch, and <FIG> shows an exploded view thereof. The electrical switch comprises a frame <NUM>, an operating shaft <NUM>, a bridge member <NUM>, an anti-tilting member <NUM>, a movable contact system, a stationary contact system and a return spring system <NUM>.

The frame <NUM> comprises a first frame portion <NUM>, and a second frame portion <NUM>. A mechanism of the electrical switch is mounted in the frame <NUM>. The operating shaft <NUM> is rotatable relative to the frame <NUM> between a first shaft position and a second shaft position. The bridge member <NUM> is made of electrically insulating material, and is movable in a depth direction relative to the frame <NUM> between a first bridge position and a second bridge position by rotation of the operating shaft <NUM>, wherein the depth direction is parallel with the rotation axis of the operating shaft <NUM>.

The movable contact system has four movable contacts <NUM>. The movable contacts <NUM> are electrically insulated from each other. Each of the movable contacts <NUM> is movable relative to the frame <NUM> between a connected position and a disconnected position such that the connected position corresponds to a connected state of the electrical switch, and the disconnected position corresponds to a disconnected state of the electrical switch. The stationary contact system has four stationary contact pairs each comprising a first stationary contact <NUM> and a second stationary contact <NUM>. The stationary contact system is stationary mounted relative to the frame <NUM>.

<FIG> show portions of a mechanism of the electrical switch shown in <FIG> in the connected state of the electrical switch. <FIG> show portions of the mechanism of the electrical switch shown in <FIG> in a disconnected state of the electrical switch. In <FIG> and <FIG>, the stationary contact system and an operating shaft spring system are shown, while said components are omitted from <FIG>, <FIG> in order to better show other parts of the mechanism.

In the connected state of the electrical switch, the first stationary contact <NUM> and the second stationary contact <NUM> of each stationary contact pair are electrically conductively connected to each other by a corresponding movable contact <NUM> of the movable contact system. In the disconnected state of the electrical switch the first stationary contact <NUM> and the second stationary contact <NUM> of each stationary contact pair are electrically separated from each other.

A rotation of the operating shaft <NUM> from the first shaft position to the second shaft position provides an opening event in which the bridge member <NUM> moves from the first bridge position to the second bridge position, and the electrical switch transfers from the connected state to the disconnected state. During the opening event, the operating shaft <NUM> is adapted to exert a first opening force to the bridge member <NUM>, and the bridge member <NUM> is adapted to exert forces to the movable contacts <NUM> for moving the movable contacts <NUM> from the connected position to the disconnected position. The first opening force is an off-centre force such that its vector is located at a distance from a centre of mass of the bridge member <NUM> in the lateral direction. Herein, the first opening force is a vector sum of a plurality of component forces exerted by the operating shaft <NUM> to the bridge member <NUM> during the opening event. Referring to <FIG>, the bridge member <NUM> is adapted to exert downwards forces to the movable contacts <NUM> during the opening event.

The anti-tilting member <NUM> is movable in a lateral direction relative to the frame <NUM> between a first position and a second position by rotation of the operating shaft <NUM>, the lateral direction being perpendicular to the depth direction. The anti-tilting member <NUM> is adapted to move exclusively in the lateral direction relative to the frame <NUM>.

The anti-tilting member <NUM> is adapted to exert a second opening force to the bridge member <NUM> during the opening event, the second opening force being parallel to the first opening force and spaced apart from it in the lateral direction. In the lateral direction, the second opening force is located on an opposite side of the centre of mass of the bridge member <NUM> than the first opening force. Herein, the second opening force is a vector sum of a plurality of component forces exerted by the anti-tilting member <NUM> to the bridge member <NUM> during the opening event.

The anti-tilting member <NUM> comprises a first ramp surface <NUM>, and the bridge member <NUM> comprises a second ramp surface <NUM> adapted to co-operate with the first ramp surface <NUM> during the opening event such that said co-operation provides the second opening force. The first ramp surface <NUM> is best seen in <FIG>, which shows the anti-tilting member <NUM> from a direction perpendicular to both the depth direction and the lateral direction. The second ramp surface <NUM> is best seen in <FIG>, which shows the portion of the mechanism from a direction perpendicular to both the depth direction and the lateral direction.

An angle of the first ramp surface <NUM> relative to the depth direction is approximately <NUM>°. In an alternative embodiment, an angle of the first ramp surface relative to the depth direction is in a range of <NUM>°-<NUM>°. Shapes of the first ramp surface and the second ramp surface are selected as a pair such that co-operation thereof is able to provide the second opening force.

In <FIG>, the operating shaft <NUM> is in the first shaft position, the bridge member <NUM> is in the first bridge position, the movable contacts <NUM> are in their connected positions, and the anti-tilting member <NUM> is in the first position thereof. In <FIG>, the operating shaft <NUM> is in the second shaft position, the bridge member <NUM> is in the second bridge position, the movable contacts <NUM> are in their disconnected positions, and the anti-tilting member <NUM> is in the second position thereof.

The operating shaft <NUM> comprises a first screw thread surface <NUM>, and the bridge member <NUM> comprises a second screw thread surface <NUM> adapted to co-operate with the first screw thread surface <NUM> during the opening event such that said co-operation provides the first opening force. The operating shaft <NUM> is adapted to remain stationary in the depth direction during a rotation between the first shaft position and the second shaft position.

The first screw thread surface <NUM> is best seen in <FIG> showing the operating shaft <NUM> obliquely from side. The second screw thread surface <NUM> is best seen in <FIG>, which illustrate co-operation of the first screw thread surface <NUM> and the second screw thread surface <NUM> during the opening event of the electrical switch. In <FIG>, the electrical switch in the connected state, and in <FIG>, the electrical switch in the disconnected state. In <FIG>, the mechanism is shown in cross section, and several components have been omitted in order to better show the co-operation between the first screw thread surface <NUM> and the second screw thread surface <NUM>. In <FIG>, image planes are perpendicular to the lateral direction.

The operating shaft <NUM> comprises a gear member <NUM>, and the anti-tilting member <NUM> comprises a gear rack member <NUM> adapted to co-operate with the gear member <NUM> such that a movement of the anti-tilting member <NUM> from the first position to the second position during the opening event is provided by forces exerted by the gear member <NUM> to the gear rack member <NUM>.

The gear member <NUM> is best seen in <FIG> showing the operating shaft <NUM> from a direction parallel to the rotation axis of the operating shaft <NUM>. The gear rack member <NUM> is best seen in <FIG> showing the anti-tilting member <NUM> from a direction parallel to the depth direction. Teeth of the gear member <NUM> and gear rack member <NUM> are compatible with each other in order to provide said co-operation.

The return spring system <NUM> is adapted to exert a return force to the movable contact system in order to return the movable contacts <NUM> to the connected position if the movable contacts <NUM> are deflected therefrom in the direction of the disconnected position. The return spring system <NUM> comprises four return springs <NUM>, <NUM>, <NUM> and <NUM>. Each of the return springs is in contact with a corresponding movable contact <NUM>.

The return springs of the return spring system <NUM> are located symmetrically with respect to the bridge member <NUM> such that a vector sum of forces exerted by the return spring system <NUM> to the movable contacts <NUM> passes through the centre of mass of the bridge member <NUM>. Therefore, the forces exerted by the return spring system <NUM> to the movable contacts <NUM> do not tilt the bridge member <NUM>.

In an alternative embodiment, the return spring system comprises a first return spring and a second return spring located on opposite sides of a centre of mass of the bridge member in the lateral direction, and the return force is directed such that an absolute value of a torque provided by the return force to the bridge member is smaller than an absolute value of a torque provided by the first opening force.

A rotation of the operating shaft <NUM> from the second shaft position to the first shaft position is adapted to provide a closing event in which the bridge member <NUM> moves from the second bridge position to the first bridge position, and the electrical switch transfers from the disconnected state to the connected state. During the closing event, the return spring system <NUM> is adapted to exert forces to the movable contacts <NUM> for moving the movable contacts <NUM> from the disconnected position to the connected position. The movable contacts <NUM> exert forces to the bridge member <NUM> for moving the bridge member <NUM> from the second bridge position to the first bridge position.

Claim 1:
An electrical switch comprising:
a frame (<NUM>);
an operating shaft (<NUM>) rotatable relative to the frame (<NUM>) between a first shaft position and a second shaft position;
a bridge member (<NUM>) movable in a depth direction relative to the frame (<NUM>) between a first bridge position and a second bridge position by rotation of the operating shaft (<NUM>), wherein the depth direction is parallel with a rotation axis of the operating shaft (<NUM>); and
a movable contact system having a plurality of movable contacts (<NUM>), each of the movable contacts (<NUM>) being movable relative to the frame (<NUM>) between a connected position and a disconnected position such that the connected position corresponds to a connected state of the electrical switch, and the disconnected position corresponds to a disconnected state of the electrical switch,
wherein a rotation of the operating shaft (<NUM>) from the first shaft position to the second shaft position is adapted to provide an opening event in which the bridge member (<NUM>) moves from the first bridge position to the second bridge position, and the electrical switch transfers from the connected state to the disconnected state, wherein the operating shaft (<NUM>) is adapted to exert a first opening force to the bridge member (<NUM>) during the opening event,
wherein the electrical switch comprises an anti-tilting member (<NUM>) movable in a lateral direction relative to the frame (<NUM>) between a first position and a second position by rotation of the operating shaft (<NUM>), the lateral direction being perpendicular to the depth direction, characterized in that the anti-tilting member (<NUM>) is adapted to exert a second opening force to the bridge member (<NUM>) during the opening event, the second opening force being parallel to the first opening force and spaced apart from it in the lateral direction, wherein the anti-tilting member (<NUM>) comprises a first ramp surface (<NUM>), and the bridge member (<NUM>) comprises a second ramp surface (<NUM>) adapted to co-operate with the first ramp surface (<NUM>) during the opening event such that said co-operation provides the second opening force.