TECHNICAL FIELD
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The present invention relates to a switch, and more specifically, to a knife switch that effectively prevents the blade from separating from the contact.
BACKGROUND
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A knife switch is a common component in a electric circuit, which closes or opens the circuit by rotating a blade to make the blade contact with or separate from a stationary contact. In the prior art, when a knife switch is in the closed state, magnetic fields generated by currents at other locations in the circuit exerts an Ampere force on the blade through which the current flows. Typically, this Ampere force causes the blade to have a tendency to rotate the blade from the closed position to the open position, which may lead to accidental opening of the knife switch and thereby causing circuit faults.
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Accordingly, the present invention provides a knife switch that overcomes the defects in the above-mentioned prior art.
SUMMARY
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According to a first aspect of the present invention, a knife switch is provided, comprising: a housing, having a frame structure, forming a blade movement space, the housing being insulated; a stationary contact, at least partially located in the blade movement space, and electrically connected to an external circuit; a blade, capable of rotating about a second end of the blade within the blade movement space so that a first end of the blade selectively contacts or separates from the stationary contact, to accordingly electrically connect or disconnect the blade and the stationary contact, the blade having a first side facing a closing direction of the blade and a second side facing an opening direction of the blade; a magnetic conductive component, arranged at least on the first side of the blade, the magnetic conductive component having ferromagnetic properties.
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According to this embodiment, when the blade is in the closed position, the magnetic conductive component disposed on the first side of the blade changes the magnetic field distribution at the position of the blade, causing the blade through which current flows to experience an Ampere force in its closing direction, making the closure of the blade more secure, thereby reducing the risk of accidental opening of the knife switch.
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In some embodiments, the magnetic conductive component is arranged to completely surround the blade, and the plane enclosed by the magnetic conductive component is perpendicular to the length direction of the blade.
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According to this embodiment, where the magnetic conductive component completely surrounds the blade, the external magnetic field is almost entirely shielded by the magnetic conductive component, causing the blade to be almost completely free from the Ampere force in the opening direction of the blade caused by the magnetic field generated by the current at other locations in the circuit, thereby reducing the risk of accidental opening of the knife switch.
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In some embodiments, the magnetic conductive component is provided with a magnetic conductive component opening on the second side of the blade along a direction parallel to the length direction of the blade.
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According to this embodiment, the presence of the magnetic conductive component opening, on the basis of the blade being almost completely free from the Ampere force in the opening direction of the blade, further causes the blade to experience an Ampere force toward the closing direction of the blade, thereby further reducing the risk of accidental opening of the knife switch.
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In some embodiments, the magnetic conductive component is provided with one or more magnetic conductive component notches on its surface.
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According to this embodiment, hazards caused by eddy current thermal effects generated during operation of the magnetic conductive component can be reduced.
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In some embodiments, the magnetic conductive component is arranged near the stationary contact.
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According to this embodiment, the moment of the Ampere force toward the closing direction of the blade acting on the blade is relatively large, further reducing the risk of accidental opening of the knife switch.
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In some embodiments, the magnetic conductive component is arranged in a U-shape opening toward the second side of the blade and surrounding the blade.
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According to this embodiment, the magnetic conductive component can be fixed to the insulation package of the stationary contact, and the blade can contact or separate from the stationary contact through the U-shaped opening of the magnetic conductive component.
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In some embodiments, the magnetic conductive component is arranged at an intermediate portion of the blade in the length direction of the blade.
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According to this embodiment, the magnetic conductive component can be fixed to the insulation package of the blade, making the arrangement of the magnetic conductive component more flexible.
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In some embodiments, the knife switch further comprises a drive shaft, the drive shaft is partially enclosed to form a space accommodating the blade, the blade is fixed inside the drive shaft, the drive shaft drives the blade to perform rotational movement, and the drive shaft is insulated.
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According to this embodiment, closing and opening of the knife switch can be controlled by operating the drive shaft.
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According to a second aspect of the present invention, an electric circuit is provided, comprising the knife switch according to the first aspect of the present invention, wherein closing and/or opening of the electric circuit is controlled by electrical connection and/or electrical insulation between the blade and the stationary contact.
BRIEF DESCRIPTION OF DRAWINGS
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- Figure 1 shows a schematic view of a knife switch according to an embodiment of the present invention in the closed state.
- Figure 2 shows a schematic view of the knife switch according to an embodiment of the present invention in the open state.
- Figure 3 shows a schematic view of a magnetic conductive component according to an embodiment of the present invention.
- Figure 4 shows a schematic view illustrating the working principle of the knife switch according to an embodiment of the present invention.
- Figure 5 shows a schematic view of the knife switch of another embodiment of the present invention.
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Reference numerals: knife switch 100, housing 110, blade 120, first side 121, second side 122, stationary contact 130, magnetic conductive component 140, magnetic conductive component opening 142, magnetic conductive component notch 144; cable connection bar 150.
DETIALED DESCRIPTION
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To make the objectives, solutions, and advantages of the technical solution of the present invention clearer, the following will, with reference to the accompanying drawings of the specific embodiments of the present invention, clearly and completely describe the technical solutions of the embodiments of the present invention. Unless otherwise stated, terms used herein have their ordinary meanings in the art. Identical reference numerals in the drawings denote identical components.
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Figure 1 shows a schematic view of a knife switch 100 according to an embodiment of the present invention in a closed state. The knife switch 100 comprises a housing 110, a blade 120, a stationary contact 130, and a magnetic conductive component 140. Although Figure 1 shows three blades 120, the present invention is not intended to limit the number of blades and may include any number of blades. The housing 110 is partially enclosed to form a space for accommodating movement of the blade 120. The stationary contact 130 is disposed on the housing 110 and protrudes from the housing 110 toward the blade 120, and a second end of the stationary contact 130 is electrically connected to an external circuit. The blade 120 has an elongated shape and is rotatable about a second end of the blade 120 so that a first end the blade 120 selectively contacts or separates from a first end of the stationary contact 130 to electrically connect or insulate the blade 120 from the stationary contact 130. The blade 120 has a first side 121 facing the closing direction of the blade and a second side 122 facing the opening direction of the blade. When the blade 120 is electrically connected to the stationary contact 130, the first side 121 of the blade 120 at least partially abuts against an inner side of the housing 110.
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As shown in Figure 1, when the above-described knife switch 100 is closed, an upward current in the cable connection bar 150 produces, at the blade 120, a magnetic field perpendicular to the circuit plane and directed inward. This magnetic field exerts an upward Ampere force on the blade 120 through which a rightward current flows, causing the blade 120 to have a tendency to separate from the stationary contact 130, creating a risk of undesired opening of the knife switch 100 (changing from the closed state in Figure 1 to the open state in Figure 2). To overcome this defect, the knife switch 100 further includes a magnetic conductive component 140. The magnetic conductive component 140 is disposed at least on the first side 121 of the blade 120, and the magnetic conductive component 140 has ferromagnetic properties. When the blade 120 is in the closed position, the magnetic conductive component 140 located on the first side of the blade 120 changes the magnetic field distribution at the position of the blade, causing the blade 120 through which current flows to experience an Ampere force directed toward the magnetic conductive component 140 (that is, toward the side of the housing 110 against which the blade 120 abuts), making the closing of the blade 120 more secure and reducing the risk of accidental opening of the knife switch 100. It should be understood that, to achieve the technical effect of the present invention, the magnetic conductive component 140 must be arranged only on the first side 121 of the blade 120, whereas on the second side 122 or other sides of the blade 120, the magnetic conductive component 140 may be arranged or may be arranged. Different arrangements can achieve different technical effects, which will be described in detail below.
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Optionally, the magnetic conductive component 140 may be disposed only on the first side of the blade 120. In this case, the magnetic conductive component 140 may be planar-shaped. Such an arrangement has a simple structure and save material.
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Optionally, the magnetic conductive component 140 may be arranged to completely surround the cross-section of the blade 120, such that in the portion of the blade 120 where the magnetic conductive component 140 is arranged, the external magnetic field is almost completely shielded by the magnetic conductive component 140, so the the blade 120 is almost completely free from the Ampere force in the opening direction of the blade caused by the magnetic fields generated by the current at other locations in the circuit (for example, in the cable connection bar 150), thereby reducing the risk of accidental opening of the knife switch 100.
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Preferably, the magnetic conductive component 140 that completely surrounds the blade 120 may be provided with a magnetic conductive component opening 142 on the second side 122 of the blade 120 along a direction parallel to the length direction of the blade 120 (as shown in Figure 3). As shown in Figure 4, due to the presence of the magnetic conductive component opening 142, the magnetic conductive component 140 does not completely shield the magnetic field at the blade 120. Assuming there is a current directed into the page in the blade 120 (if there is a current directed out of the page in the blade 120, the same conclusion can be obtained through the following analysis method), this current generates a clockwise magnetic field in the magnetic conductive component 140 (viewed from outside the page into the page). At the magnetic conductive component opening 142, the magnetic field shifts downward to the blade 120. At this time, the blade 120 is in a magnetic field with a horizontally rightward component, causing the magnetic force on the blade 120 to be directed from outside the magnetic conductive component opening 142 to inside the magnetic conductive component opening 142 (that is, toward the first side 121 of the blade 120), thereby causing the blade 120 to experience a magnetic force in the closing direction of the blade, thus further reducing the risk of accidental opening of the knife switch 100.
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Preferably, the magnetic conductive component 140 may be provided with one or more magnetic conductive component notches 144 on its surface, used to reduce hazards caused by eddy current thermal effects generated during operation of the magnetic conductive component 140.
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Preferably, as shown in Figure 5, the magnetic conductive component 140 may be arranged near the stationary contact 130. In this case, the magnetic force acting on the blade 120 toward the closing direction of the blade 120 acts near the stationary contact 130. Because the stationary contact 130 is relatively far from the second end of the blade 120 (the pivot point of the blade 120's rotation), the moment of the magnetic force acting on the blade toward the closing direction of the blade is relatively large, thereby further reducing the risk of accidental opening of the knife switch 100.
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Preferably, the magnetic conductive component 140 may be arranged in a U-shape opening toward the second side 122 of the blade 120 surrounding the blade 120. In this way, the magnetic conductive component 140 can be fixed to the insulation package of the stationary contact 130, the rotational movement of the blade 120 is not obstructed by the magnetic conductive component 140, and thus the blade 120 can contact or separate from the stationary contact 130 through the U-shaped opening of the magnetic conductive component 140. Furthermore, when the U-shaped magnetic conductive component is arranged, the Ampere force acting on the blade 120 toward the closing direction of the blade is greater than the Ampere force acting on the blade 120 when the magnetic conductive component is arranged only on the first side 121 of the blade 120. Therefore, compared to arranging the magnetic conductive component 140 only on the first side 121 of the blade 120, the U-shaped magnetic conductive component can further reduce the risk of accidental opening of the knife switch 100.
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Optionally, the magnetic conductive component 140 may be arranged at an intermediate portion of the blade 120 in a length direction of the blade 120, for example, fixed to an insulation package of the blade 120. Compared with the above solution where the magnetic conductive component 140 is fixed to the stationary contact 130, in this solution, the magnetic conductive component 140 is fixed to the blade 120, so that regardless of the opening mode of the magnetic conductive component 140, the rotational movement of the blade 120 is not obstructed by the magnetic conductive component 140. In this way, the arrangement of the magnetic conductive component 140 is more flexible, for example, a closed mode, an opening mode, or a U-shaped mode may be adopted.
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Optionally, the knife switch 100 may further comprise a drive shaft arranged at the second end of the blade 120, for driving rotation of the blade 120. For example, the drive shaft may be operated manually or electrically to drive rotation of the blade 120 to control closing or opening of the knife switch 100.
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Optionally, the knife switch 100 further comprises a cable connection bar 150. One end of the cable connection bar 150 supports the second end of the blade 120 and is electrically connected to the second end of the blade 120. The other end of the cable connection bar 150 is electrically connected to an external circuit.
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By using the above-described knife switch 100, electrical connection and/or electrical insulation between the blade 120 and the stationary contact 130 can be controlled to control closing and/or opening of the circuit. By arranging the magnetic conductive component 140, the risk of accidental opening of the knife switch 100 is reduced, and the reliability of the circuit is improved.
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Various exemplary embodiments of the present invention have been described in detail herein with reference to preferred embodiments. However, those skilled in the art may understand that, without departing from the concept of the present invention, various modifications and changes can be made to the above specific embodiments, and various technical features and structures proposed by the present invention can also be combined without exceeding the protection scope of the present invention. The protection scope of the present invention is defined by the appended claims.