EP3232460B1

EP3232460B1 - Surge protection device and thermal tripping mechanism thereof

Info

Publication number: EP3232460B1
Application number: EP15867324.4A
Authority: EP
Inventors: Fan Yang; Renjie LI; Jianrong JIN; Yang Cao; Weijun GE
Original assignee: Noark Electrics Shanghai Co Ltd; SEARI Electric Technology Co Ltd
Current assignee: Noark Electrics Shanghai Co Ltd; SEARI Electric Technology Co Ltd
Priority date: 2014-12-11
Filing date: 2015-12-02
Publication date: 2019-10-02
Anticipated expiration: 2035-12-02
Also published as: EP3232460A1; WO2016091103A1; CN104392868A; PL3232460T3; EP3232460A4; CN104392868B

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the field of low voltage electric apparatus, more particularly, relates to a surge protection device of a low voltage electric apparatus.

2. The Related Art

In a low voltage power distribution system, a Surge Protection Device (SPD) is usually used to protect overvoltage caused by external influence, such as lightning. A III-type surge protection device is used for a terminal electric apparatus. At present, existing III-type SPDs in the market are mainly used for providing common-mode protection. Due to the fact that common-mode protection has certain limitations, there is a demand for a surge protection device which can simultaneously provide common-mode protection and differential-mode protection.
A surge protection device with a Y-shaped layout can simultaneously provide common-mode protection and differential-mode protection. The Y-shape layout means that the surge protection device comprises two voltage-sensitive resistors and a discharge tube. The two voltage-sensitive resistors share one electrode and are connected with the discharge tube in series. The two voltage-sensitive resistors and the discharge tube are connected to form a Y-shaped structure.
The key of the Y-shaped layout is the design of a thermal tripping mechanism between the two voltage-sensitive resistors and the discharge tube. The basic protection principle of the surge protection device is: when overvoltage occurs, a conductive path is turned on to discharge a current. When no overvoltage exists, almost no current flows through the conductive path. However, when the surge protection device is degraded and causes a rise in temperature, the circuit will be disconnected as well. This is a situation that the surge protection device malfunctions. The degradation of the surge protection device causes a rise in temperature, the elements of the surge protection device are heated when the temperature rises. A thermal tripping mechanism is heated and tripped, the circuit is then disconnected. The existing Y-shaped layout surge protection device uses two types of thermal tripping mechanisms: an electronic type or a mechanical type. The electronic type thermal tripping mechanism applies a temperature fuse. Although the temperature fuse has high reliability in design, but the abnormal conditions which can be handled by a single temperature fuse are very limited. The temperature fuse may be damaged and malfunctioned due to some unexpected reasons such as aging failure, then the circuit cannot be disconnected in time when elements of the surge protection component is in thermal failure. Therefore, the overall reliability of the temperature fuse is low. Further, the temperature fuse has a high welding difficulty. An ordinary welding mode may cause the temperature fuse to be accidentally fused, so that only a local welding mode such as laser welding can be adopted. As to the mechanical type thermal tripping mechanism, pins of a plurality of surge protection elements are welded together through a low melting point alloy. The number of the welding spots can be one or multiple. If one welding spot is adopted, pins of the two pressure-sensitive resistors and the pin of one discharge tube are welded at one spot, the welding difficulty is high, and it is easy to cause a "wire drawing" during a tripping process. If multiple welding spots are adopted, it is not easy to concentrate heat and the tripping performance is not stable.
US 2013/271890 A1 describes a transient voltage surge suppression device including a varistor assembly having a compact thickness, and a disconnect element carrying a separable contact along a linear axis to disconnect the varistor element from external circuitry.
US 2011/170217 A1 describes a thermally protected surge suppression device comprising a housing and a base seat with a mounting plate. The base seat is provided with a surge suppression component and a thermal protection device, and the thermal protection device further comprises a metal bulge electrically connecting to the electrode of the surge suppression component, a compression spring, a slider provided with an arc extinguishing component movable on the guide-track groove. In normal working condition, the conductive metal member electrically connects to the metal bulge via a low temperature solder. When the surge suppression component fails, the low temperature solder is melt owing to being passed through the power frequency fault current, the conductive metal member is disconnected from the metal bulge, the compression spring pushes the arc extinguishing component to move to obstruct the disconnected gap, and form an airflow to extinguish the electric arc between the conductive metal member and the metal bulge.
US 2011/222199 A1 describes a surge protector having a thermal separating device and an error display, and at least two first protection elements, particularly disk-shaped varistors, and at least one second protection element, particularly a gas arrester, wherein the first and the at least one second protection elements are switched in a Y arrangement. The surge protector further comprises a means for the mechanical biasing of the thermal separating device, wherein the thermal separating device has a low-melting solder, and the first protection elements are disposed in a device housing such that a connection arm of a protection element is positioned opposite the connection arm of the further protection element at a distance, and the thermal separating device is predominantly positioned in the distance space.

SUMMARY

The present invention provides a surge protection device and a thermal tripping mechanism thereof. A Y-shaped internal layout of the surge protection device can be easily and stably realized. A common-mode protection and a differential-mode protection can be both realized.
According to the present invention, a thermal tripping mechanism of a surge protection device as defined in claim 1 is provided. The thermal tripping mechanism comprises an elastic mechanism. Two voltage-sensitive resistors and one discharge tube form a Y-shaped layout, the two voltage-sensitive resistors are directly or indirectly connected with the discharge tube by using a thermal fusing material. The elastic mechanism comprises an elastic element and a sliding element, the elastic element drives the sliding element to move by an elastic force. When the two voltage-sensitive resistors are both in a normal working state, i.e., are both intact, the thermal fusing material does not reach a fusing temperature, the two voltage-sensitive resistors and the discharge tube are configured to form a conductive path, and the elastic element is configured to be in an energy storage state. When at least one of the voltage-sensitive resistors is in an abnormal working state, i.e., is degraded due to surge voltage, the thermal fusing material reaches the fusing temperature and is fused, the elastic element is configured to release energy for driving the sliding element to move, and the sliding element is configured to move to cut off the conductive path. The two voltage-sensitive resistors are connected with the discharge tube through a connection piece. The connection piece comprises a conductive material, a first end of the connection piece is provided with two first connection grooves, the two first connection grooves are connected with pins of the two voltage-sensitive resistors respectively, a second end of the connection piece is provided with a second connection groove, the second connection groove is connected with a pin of the discharge tube, wherein the connection piece is connected with at least one of the two voltage-sensitive resistors and the discharge tube through a thermal fusing material.
According to an embodiment, the sliding element is a sliding block, the sliding block is connected with the connection piece, the elastic element drives the sliding block to move by an elastic force.
According to an embodiment, the connection piece is elongated. The first end of the connection piece is provided with a branch portion which extends laterally. Two semicircular first connection grooves are formed on the branch portion. The second end of the connection piece is provided with a circular second connection groove. A sliding block hole is formed between the first connection groove and the second connection groove. The elastic element is a spring, one end of the spring is fixed on a shell of the surge protection device, the other end of the spring is fixed on the sliding block, and the spring is energy-stored. The sliding block is configured to move along a sliding chute in the shell of the surge protection device, the sliding block is provided with a protrusion, the protrusion is placed in the sliding block hole of the connection piece. The spring is configured to release energy and pulls the sliding block to drive the connection piece to move.
According to an embodiment, the sliding element is a sliding component, the sliding component is disposed within the shell of the surge protection device and moves in the shell of the surge protection device. The elastic element is connected with the sliding component, the elastic element is configured to drive the sliding component to move by an elastic force. Pins of the two voltage-sensitive resistors and the discharge tube are connected through a thermal fusing material. The two voltage-sensitive resistors are fixedly assembled in the shell of the surge protection device, the discharge tube is assembled on the sliding component and is configured to move along with the sliding component.
According to an embodiment, the elastic element is a spring, one end of the spring is fixed within the shell of the surge protection device, the other end of the spring is fixed on the sliding component, the spring is energy-stored. A sliding groove is formed in the shell, the sliding component is configured to move along the sliding groove. The spring is configured to release energy and pushes the sliding component to drive the discharge tube to move.
According to an embodiment, a surge protection device is provided, comprising the above-mentioned thermal tripping mechanism. The surge protection device is defined in claim 6.
According to an embodiment, the connection piece is elongated, a first end of the connection piece is provided with a branch portion which extends laterally. The two first connection grooves are semicircular and formed on the branch portion. The second connection groove is circular. A sliding block hole is formed between the first connection groove and the second connection groove. The elastic element is a spring and the sliding element is a sliding block, the sliding block is configured to move along a sliding chute in the shell of the surge protection device. The sliding block is provided with a protrusion, the protrusion is placed in the sliding block hole of the connection piece. One end of the spring is fixed on a shell of the surge protection device, the other end of the spring is fixed on the sliding block. The spring is energy-stored. When the spring releases energy, the spring is configured to pull the sliding block to drive the connection piece to move.
According to an embodiment, the sliding element is a sliding component, the sliding component is disposed within the shell of the surge protection device, a sliding chute is provided in the shell and the sliding component moves along the sliding chute. The elastic element is connected with the sliding component, the elastic element is a spring, one end of the spring is fixed within the shell of the surge protection device, the other end of the spring is fixed on the sliding component. The pins of the two voltage-sensitive resistors and the discharge tube are connected through a thermal fusing material. The two voltage-sensitive resistors are fixedly assembled in the shell of the surge protection device, the discharge tube is assembled on the sliding component and is configured to move along with the sliding component. The spring is energy-stored, and when the spring releases energy, the spring is configured to push the sliding component to drive the discharge tube to move.
According to an embodiment, the surge protection device further comprises an indication component assembled on the shell, the indication component and the sliding element form a linkage mechanism. An indication window is formed in the outer contour of the shell, the indication component is assembled at a position corresponding to the indication window. When the sliding element is not driven by the elastic element, the indication component covers the indication window, when the sliding element is driven by the elastic element, the indication component is configured to move away from the indication window.
According to an embodiment, a dovetail groove is formed in the bottom of the shell, the dovetail groove is gradually narrowed from top to bottom. The surge protection device is assembled in an U-shaped groove in a base, the U-shaped groove is provided with a positioning block matched with the dovetail groove. The positioning block comprises a rod portion and an end portion, the end portion is larger than the rod portion, and the end portion forms an inclined guide surface with arc surfaces on both ends.
The surge protection device of the present invention achieves a reliable and feasible Y-shaped layout of internal components through its thermal tripping mechanism, so that a III-type surge protection device can achieve common-mode protection and differential-mode protection at a same time. The thermal tripping mechanism makes all the pins of the surge protection element as close as possible under a premise of ensuring the welding stability. Therefore, the temperature is more concentrated and the product can be tripped more easily.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features, natures, and advantages of the invention will be apparent by the following description of the embodiments incorporating the drawings, wherein,

FIG. 1 illustrates a structure diagram of a surge protection device according to a first embodiment of the present invention.
FIG. 2A and FIG. 2B illustrate structure diagrams of connection pieces according to different embodiments of the present invention.
FIG. 3 illustrates a structure diagram of a thermal tripping mechanism of a surge protection device according to a first embodiment of the present invention.
FIG. 4A and FIG. 4B illustrate structure diagrams of a surge protection device in a normal working position and a disconnection position according to the first embodiment of the present invention. FIG. 4A and FIG. 4B illustrate the structure of the surge protection device from the other side shown in FIG. 1.
FIG. 5A and FIG. 5B illustrate structure diagrams of a surge protection device according to a second embodiment of the present invention from different perspectives. The surge protection device shown in FIG. 5A and FIG. 5B is in an untripped state.
FIG. 6 illustrates a structure diagram of a surge protection device according to a second embodiment of the present invention. The surge protection device shown in FIG. 6 is in a tripping state.
FIG. 7 is a schematic structural diagram of a surge protection device according to a second embodiment of the present invention matching with a base.
FIG. 8 illustrates an enlarged view of a dovetail groove and a positioning block when the surge protection device according to a second embodiment of the present invention is matched with a base.

DETAILED DESCRIPTION OF EMBODIMENTS

Firstly, the term "connect" used in this specification is described herein. The specification relates to a mechanical and electrical structure, therefore, the term "connect" comprises two meanings of mechanical connection and electrical connection. A mechanical connection shall meet requirements of mechanical strength and mechanical operation, and an electrical connection shall meet requirements of electrical conduction. For a skilled person in the art, considering context, it shall be clear that each "connect" used in the specification shall refer to a mechanical connection, an electrical connection or both.
Referring to FIG. 1, FIG. 4A and FIG. 4B, a surge protection device according to a first embodiment is disclosed. FIG. 1, FIG. 4A and FIG. 4B illustrate the structure of the surge protection device according to the first embodiment from different perspectives. The surge protection device comprises: a shell, voltage-sensitive resistors, a discharge tube, a connection piece and an elastic mechanism.
According to an embodiment, the shell is formed by assembling a plurality of shell components. According to the illustrated embodiment, the shell is formed by assembling two shell components: an exterior component 109 and an interior component 102. Due to the fact that various elements are arranged within the shell, a shell body formed by assembling components enables an easier arrangement of the elements within the shell. Within the shell, an element support is formed by the interior component 102. The element support comprises a partition wall 110 (referring to FIG. 1) and a pin support 114 (referring to FIG. 3 and FIG. 4A). In an outer contour of the shell, openings are formed by the exterior component 109. The openings comprise a pin opening (not numbered) and a signal opening 111 (referring to FIG. 4B). The shell is made of an insulating material, such as plastic.
Two voltage-sensitive resistors 103 and one discharge tube 108 are disposed on the element support in the shell. According to the illustrated embodiment, each voltage-sensitive resistor 103 is disc-type voltage-sensitive resistor. The two voltage-sensitive resistors 103 are respectively assembled on the two sides of the partition wall 110. The partition wall 110 is part of the interior component 102 of the shell. The partition wall 110 is made of an insulating material and is made of the same material as the shell. Each voltage-sensitive resistor is provided with two pins. First pins of the two voltage-sensitive resistors are connected with one insertion pin respectively. The insertion pins extend out of the shell through the pin openings in the shell. According to the drawings, the insertion pin which is connected with the first pin of the voltage-sensitive resistor is numbered as 104a. The discharge tube 108 is assembled on the element support. The discharge tube is located on one side of the partition wall 110. According to the illustrated embodiment, the discharge tube is located on the side shown in FIG. 4A and FIG. 4B. The discharge tube 108 is also provided with two pins. A first pin of the voltage-sensitive resistor is also connected with an insertion pin. The insertion pin extends out of the shell through the pin opening in the shell. According to the drawings, the insertion pin which is connected with the first pin of the discharge tube is numbered as 104b.
The two voltage-sensitive resistors 103 are connected with the discharge tube 108 through a connection piece 107. FIG. 2A and FIG. 2B illustrate structure diagrams of connection pieces according to different embodiments of the present invention. Although the structures and the shapes of the connection pieces shown in FIG. 2a and FIG. 2b are slightly different, both connection pieces have the following structure: a first end of the connection piece is provided with two branched first connection grooves, which are connected with second pins of the two voltage-sensitive resistors respectively; a second end of the connection piece is provided with a second connection groove, which is connected with a second pin of the discharge tube. According to the illustrated embodiment, the connection piece 107 is elongated. The first end of the connection piece is provided with a branch portion which extends laterally, two semicircular first connection grooves 116 are formed on the branch portion. The second end of the connection piece is provided with a circular second connection groove 118. A sliding block hole 117 is formed between the first connection groove and the second connection groove. FIG. 3 illustrates a structure diagram of a thermal tripping mechanism of a surge protection device according to a first embodiment of the present invention. As shown in FIG. 3, the second pins 112 of the two voltage-sensitive resistors located on both sides of the partition wall 110 extend downwards. A pin support 114 of the element support is used for positioning the second pin 112. The pin support 114 is in a form of two notches. The two second pins 112 are placed in the notches and the notches are used for fixing the positions of the two second pins 112. A spacing space 113 is formed between the two second pins 112. The spacing space 113 is used for accommodating the body of the connection piece 107. The two first connection grooves 116 on the connection piece are in contact with the two second pins 112. The semicircular first connection groove 116 just surrounds the second pin 112. According to the illustrated embodiment, the two first connection grooves 116 of the connecting piece are connected with the second pins 112 by using a thermal fusing material. According to an embodiment, the thermal fusing material is low temperature solder. The second pin 112 is welded in the first connection groove 116 through the low-temperature solder. The second pin of the discharge tube 108 is placed into the second connection groove 118. The connection between the second pin of the discharge tube 108 and the second connection groove 118 is not required to be welded, only common electrical connection is required.
As shown in FIG. 4A and FIG. 4B, the surge protection device further comprises an elastic mechanism. The elastic mechanism comprises an elastic element 105 and a sliding element 106. The elastic mechanism is arranged on one side of the partition wall 110. According to the illustrated embodiment, the elastic mechanism and the discharge tube 108 are located on the same side, which is the side shown in FIG. 4A and FIG. 4B. The elastic element 105 is a spring, one end of the spring 105 is fixed on the shell. According to the illustrated embodiment, a protruding portion is provided on the interior component 102 for fixing one end of the spring. The other end of the spring 105 is fixed on the sliding element 106. The spring is in an energy storage state when the surge protection device works normally. The spring releases energy when tripping is needed. According to the illustrated embodiment, the spring 105 is stretched to store energy when the surge protection device works normally. A sliding chute is formed on the interior component 102 of the shell. The sliding element 106, which may have the form of a sliding block, moves along a sliding chute. The sliding element 106 is provided with a protrusion, which is placed in the sliding block hole 117 of the connection piece. When the spring 105 is retracted to release energy, the spring 105 pulls the sliding element 106, the sliding element 106 drives the connection piece 107 to move together through the coordination of the protrusion and the sliding block hole 117.
FIG. 4A and FIG. 4B illustrate structure diagrams of a surge protection device in a normal working position and a disconnection position respectively. During normal operation, no surge voltage exists in the circuit, so that the two voltage-sensitive resistors are at normal working temperature and low-temperature solder (the thermal fusing material) is in solid state. A pin of the voltage-sensitive resistor and the first connection groove of the connection piece are connected together by the solid low-temperature solder. The spring is in a stretched state for energy storage, as shown in FIG. 4A. The pin, the voltage-sensitive resistor, the connection piece, the discharging tube and the insertion pin form an electrical path at this moment. When surge voltage occurs in the circuit, if one or both of the voltage-sensitive resistors is degraded, a leakage current will increase and the temperature will rise continuously. Or when an overvoltage exceeds the expected value, the voltage-sensitive resistor and the discharge tube will be broken down and short circuit will occur, which may cause the temperature to rise sharply. The temperature rises and heats the low-temperature solder, so that the solder is melted. At this moment, the spring is not subjected to external force, and will retract under the elastic force of the spring itself. The spring drives the sliding block to move along the sliding chute, and further drives the connection piece to move. The second pin of the voltage-sensitive resistor is separated from the first connection groove of the connection piece after the connection piece moves. Then the electrical path is cut off and tripping is realized, as shown in FIG. 4B. Continue with FIG. 4B, the second pin of the discharge tube will have a certain deformation after moving along with the connection piece, so that it requires that the second pin of the discharge tube have certain toughness. Further continue with FIG. 4B, after the sliding element 106 moves, the signal opening 111 which is originally shielded by the sliding element 106 is in an open state. According to an embodiment, the signal opening 111 matches with an alarm device on the base, when the signal opening 111 is opened, the alarm device will give an alarm to inform a tripping situation.
According to the above description of the tripping process, the requirements for the material of the connection piece 107 are as follows: the connection piece 107 shall be made of conductive material, such as metal. For example, the connection piece 107 itself is made of metal. Or the connection element 107 comprises conductive material, the conductive material is disposed along the connection piece 107 and forms a conductive path between the first connection groove 116 and the second connection groove 118, so that the voltage-sensitive resistors and the discharge tube will form a conducting path when being connected with the connection piece. For example, the connection piece 107 is a circuit board containing conductive paths. The material of the connection piece is preferably heat-gathered, and the heat accumulation is beneficial to fusing of the thermal fusing material. Under the condition that other design requirements are met, the volume of the connection piece 107 shall be as small as possible, so that heat dissipation can be reduced and heat accumulation can be facilitated.
It should be understood that, although in the embodiment described above, the connection piece 107 is connected with the voltage-sensitive resistors 103 through a thermal fusing material, while the connection piece 107 is connected with the discharge tube in a common connection. The connection piece 107 can also be connected with the discharge tube 108 through a thermal fusing material. In an actual application, it requires that the connection piece shall connect with at least one of the voltage-sensitive resistors and the discharge tube through a thermal fusing material.
Meanwhile, according to the above embodiment, when tripping operation is carried out, the second pin of the voltage-sensitive resistors 103 will receive a pulling force. In order to prevent the pin from being damaged, the second pin is required to have a certain mechanical strength. Under the condition that other design requirements are met, the length of the second pin of the voltage-sensitive resistors shall be as short as possible so as to increase the mechanical strength. The second pin of the discharge tube will deform along with the movement of the connection piece, so that it requires that the second pin of the discharge tube shall have enough toughness. It requires that the second pin can deform within the range of movement of the connection piece without affecting the electrical function of the second pin.
Continue with FIG. 4A and FIG. 4B, the surge protection device further comprises an indication component 101. The indication component 101 is assembled on the shell. According to the illustrated embodiment, the indication component 101 is strip-shaped and is an indication strip. An indication window 115 is formed on the outer contour of the shell, that is, on the exterior component 109. The indication component 101 is assembled at a position corresponding to the indication window 115. The indication component 101 and the sliding element 106 form a linkage mechanism. When the sliding element 106 is not pulled by the spring 105, the indication component 101 covers the indication window 115, as shown in FIG. 4A. When the sliding element 106 is pulled by the spring 105, the indication component 101 is moved away from the indication window 105, as shown in FIG. 4B. According to an embodiment, the indication component and the indication window are coated with different colors so as to indicate different states. For example, the indication component may be coated with green, and in a normal working state, the indication window is covered by the indication component and only the green indication component can be observed, which indicates that the working state is normal. In the tripping state, the sliding block moves and the indication component linked with the sliding block also moves. The indication component is moved away from the indication window, and the indication window is exposed. The indication window may be coated with red. If a red indication window is observed, it means that the working state is abnormal and is in the tripping state.
Although the above embodiment is described in combination of a surge protection device with the above structure, it should be understood by those skilled in the art that the thermal tripping mechanism can be applied to surge protection devices with other structures. The thermal tripping mechanism should be understood to have the following design:
A thermal tripping mechanism of a surge protection device comprises a connection piece and an elastic mechanism.
Two voltage-sensitive resistors and one discharge tube form a Y-shaped layout. The two voltage-sensitive resistors are connected with the discharge tube through the connection piece.
The elastic mechanism comprises an elastic element and a sliding element. The elastic element drives the sliding element to move by an elastic force.
The connection piece comprises a conductive material, a first end of the connection piece is provided with two branched first connection grooves. The two first connection grooves are connected with pins of the two voltage-sensitive resistors respectively. A second end of the connection piece is provided with a second connection groove. The second connection groove is connected with a pin of the discharge tube. The connection piece is connected with at least one of the voltage-sensitive resistors and the discharge tube through a thermal fusing material.
The elastic mechanism comprises an elastic element and a sliding block, element. The sliding block is connected with the connection piece, the elastic element drives the sliding block to move by an elastic force.
When the two voltage-sensitive resistors are both in a normal working state, i.e., are both intact, the thermal fusing material does not reach a fusing temperature. The two voltage-sensitive resistors and the discharge tube form a conductive path, and the elastic element is in an energy storage state. When at least one of the voltage-sensitive resistors is in an abnormal working state, i.e., is degraded, the thermal fusing material reaches the fusing temperature and is fused, the elastic element releases energy for driving the sliding element to move, and the sliding element moves to cut off the conductive path.
The connection piece is elongated, the first end of the connection piece is provided with a branch portion which extends laterally, two semicircular first connection grooves are formed on the branch portion. The second end of the connection piece is provided with a circular second connection groove, a sliding block hole is formed between the first connection groove and the second connection groove.
The elastic element is a spring, one end of the spring is fixed on a shell of the surge protection device, the other end of the spring is fixed on the sliding block, and the spring is energy-stored. The sliding component moves along the sliding groove in the shell. The sliding block is provided with a protrusion, which is placed in the sliding block hole of the connection piece. When the spring is retracted to release energy, the spring pulls the sliding block to drive the connection piece to move.
The surge protection device according to the embodiment achieves a reliable and feasible Y-shaped layout of internal components through its thermal tripping mechanism, so that a III-type surge protection device can achieve common-mode protection and differential-mode protection at a same time. The thermal tripping mechanism uses a connection piece as auxiliary and makes all the pins of the surge protection element as close as possible under a premise of ensuring the welding stability. Therefore, the temperature is more concentrated and the product can be tripped more easily.
Referring to FIG. 5A and FIG. 5B, a surge protection device according to a second embodiment is disclosed. FIG. 5A and FIG. 5B illustrate structure diagrams of a surge protection device from different perspectives. The surge protection device comprises: a shell, two voltage-sensitive resistors, a discharge tube, a sliding component and an elastic mechanism.
An element support is formed within the shell 201, the element support comprises a partition wall for separating the two voltage-sensitive resistors. Openings are formed in the outer contour of the shell. The openings comprise a pin opening (not numbered) and a signal opening 213 (referring to FIG. 6). The shell is made of an insulating material, such as plastic.
Two voltage-sensitive resistors 203 and the discharge tube 204 are disposed on the element support in the shell. According to the illustrated embodiment, each voltage-sensitive resistor 203 is a disc-type voltage-sensitive resistor. The two voltage-sensitive resistors 203 are respectively assembled on the two sides of the partition wall. The partition wall is part of the shell. The partition wall is made of an insulating material and is made of the same material as that of the shell. Each voltage-sensitive resistor is provided with two pins. First pins of the two voltage-sensitive resistors are connected with one insertion pin respectively. The insertion pins extend out of the shell through the pin openings in the shell. According to the drawings, the insertion pin which is connected with the first pin of the voltage-sensitive resistor is numbered as 214a. The discharge tube 204 is assembled on the sliding component. The sliding component is assembled beneath the element support and the voltage-sensitive resistor, which will be described in detail below. The discharge tube 204 is also provided with two pins. A first pin of the voltage-sensitive resistor is also connected with an insertion pin. The insertion pin extends out of the shell through the pin opening in the shell. According to the drawings, the insertion pin, which is connected with the first pin of the discharge tube, is numbered as 214b.
The sliding component 202 is assembled within the shell 201 and moves in the shell. The discharge tube 204 is assembled on the sliding component 202 and moves along with the sliding component. According to the illustrated embodiment, a sliding chute is provided in the shell 201 and the sliding component 202 moves along the sliding chute. The chute is located beneath the element support and the two voltage-sensitive resistors 203, so that the sliding component 202 and the discharge tube 204 are also located beneath the voltage-sensitive resistor. The second pin 208 of the discharge tube 204 extends upwards. The elastic element 205 is connected with the sliding component 202, the elastic element 205 drives the sliding component 202 to move by an elastic force. According to the illustrated embodiment, the elastic element 205 is a spring. One end of the spring is fixed on a shell 201, the other end of the spring is fixed on the sliding component 202. The spring is energy-stored; when the spring releases energy, the spring pulls the sliding block to drive the connection piece to move. The spring is in an energy storage state when the surge protection device works normally. The spring releases energy when tripping is needed. According to the illustrated embodiment, the spring 205 is compressed to store energy when the surge protection device works normally. When the spring 205 is released to release energy, the spring 205 pushes the sliding component 202, the sliding component 202 drives the discharge tube 204 to move together.
Continue with FIG. 5A and FIG. 5B, second pins 207 of the two voltage-sensitive resistors 203 are bent. A transverse portion of the second pin 207 forms a transverse spacing structure. The transverse spacing structure means that the two second pins 207 are bent from a vertical direction to a horizontal direction, and a gap is reserved between the two second pins 207. A second pin 208 of the discharge tube 204 is placed in the middle of the transverse spacing structure. In addition, the second pin of the discharge tube and the second pin of the voltage-sensitive resistor are welded together through a thermal fusing material. According to an embodiment, the thermal fusing material is a low melting point alloy, such as low-temperature solder. The second pin 208 of the discharge tube is welded together through a low melting point alloy and the transverse spacing structure formed by two second pins 207 of the voltage-sensitive resistors.
Referring to FIG. 5A, FIG. 5B and FIG. 6, a tripping process of the surge protection device is as follows:
FIG. 5A and FIG. 5B illustrate structure diagrams of a surge protection device in normal operation state from different perspectives. FIG. 6 illustrates a structure diagram of a surge protection device in a tripping state. During normal operation, no surge voltage exists in the circuit, so that the two voltage-sensitive resistors are at normal working temperature and low-temperature solder (the thermal fusing material) is in solid state. A pin of the voltage-sensitive resistor and a pin of the discharge tube are connected together by the solid low-temperature solder. The spring is in a compressed state for energy storage, as shown in FIG. 5A and FIG. 5B. The pin, the voltage-sensitive resistor, the discharging tube and the insertion pin form an electrical path at this moment. When one or both of the voltage-sensitive resistors is degraded, a leakage current will increase and the temperature will rise continuously. Or when an overvoltage exceeds the expected value, the voltage-sensitive resistor and the discharge tube will be broken down and short circuit will occur, which may cause the temperature to rise sharply. The temperature rises and heats the low-temperature solder, so that the solder is melted after reaching fusing temperature. At this moment, the spring is not subjected to external force, and will release under the elastic force of the spring itself. The spring drives the sliding component to move along the sliding chute, and the discharging tube disposed in the sliding component moves together with the sliding component. The second pin of the discharging tube is separated from the second pin of the voltage-sensitive resistor. The electrical path is cut off and tripping is realized, as shown in FIG. 6. Continue with FIG. 6, after the sliding component 202 moves, the signal opening 213, which is originally shielded by the sliding component 202, is in an open state. According to an embodiment, the signal opening 213 matches with an alarm device on the base, when the signal opening 213 is opened, the alarm device will give an alarm to inform a tripping situation.
Referring to FIG. 7 and FIG. 8, in order to facilitate cooperation of the surge protection device and the base, a structure for matching with the base is further designed on the shell of the surge protection device according to the present invention. FIG. 7 is a schematic structural diagram of a surge protection device according to a second embodiment of the present invention matching with a base. The shell 201 of the surge protection device is assembled in a U-shaped groove in a base 211. A dovetail groove 206 is formed in the bottom of the shell 201, two side walls of the dovetail groove are gradually narrowed from top to bottom, forming inward-retracting inclined surfaces. The U-shaped groove of the base is provided with a positioning block 212 matched with the dovetail groove. FIG. 8 illustrates an enlarged view of a dovetail groove and a positioning block when the surge protection device according to a second embodiment of the present invention is matched with a base. As shown in FIG. 8, the positioning block 212 comprises a rod portion and an end portion, the end portion is larger than the rod portion, and the end portion forms an inclined guide surface with arc surfaces on both ends. The inclined guide surface of the end portion is matched with the inward-retracting inclined surface of the dovetail groove 206, guiding the shell 201 to be assembled in the U-shaped groove of the base. After the shell 201 is assembled in place, the end of the positioning block 212 clamps the dovetail groove 206, so that the surge protection device is firmly assembled on the base. When the surge protection device needs to be taken out, the positioning block 212 may have a certain deformation, as shown by the dotted lines in FIG. 8. The positioning block 212 will be opened outwards, so that the dovetail groove 206 will be withdrawn from the two positioning blocks 212, so that the surge protection device can be taken down from the base.
Although the above embodiment is described in combination of a surge protection device with the above structure, it should be understood by those skilled in the art that the thermal tripping mechanism can be applied to surge protection devices with other structures. The thermal tripping mechanism should be understood to have the following design:

A thermal tripping mechanism of a surge protection device comprises an elastic element and a sliding component;
The sliding component is disposed within the shell of the surge protection device and moves in the shell of the surge protection device.

The elastic element is connected with the sliding component, the elastic element drives the sliding element to move by an elastic force.
Two voltage-sensitive resistors and a discharge tube form a Y-shaped layout. The two voltage-sensitive resistors are connected with the discharge tube by using a thermal fusing material.
The two voltage-sensitive resistors are fixedly assembled in the shell of the surge protection device, the discharge tube is assembled on the sliding component and moves along with the sliding component.
When the two voltage-sensitive resistors are both in a normal working state, the thermal fusing material does not reach a fusing temperature. The two voltage-sensitive resistors and the discharge tube form a conductive path, and the elastic element is in an energy storage state. When at least one of the voltage-sensitive resistors is in an abnormal working state, the temperature rises, the thermal fusing material reaches the fusing temperature and is fused. The elastic element releases energy and drives the sliding component and the discharge tube to move. The conductive path is cut off.
The elastic element is a spring, one end of the spring is fixed on the shell of the surge protection device, the other end of the spring is fixed on the sliding component. The spring is compressed to store energy. A sliding chute is provided in the shell, the sliding component can slide along the sliding chute. When the spring releases to release energy, the spring pushed the sliding component to drive the discharge tube to move.
The surge protection device according to the second embodiment achieves a reliable and feasible Y-shaped layout of internal components through its thermal tripping mechanism, so that a III-type surge protection device can achieve common-mode protection and differential-mode protection at a same time. A dovetail groove is formed in the bottom of the shell of the surge protection device, and the dovetail groove is matched with a positioning block on the base, so that the surge protection device and the base are reliable in connection and convenient to assemble and disassemble.
The above embodiments are provided to those skilled in the art to realize or use the invention, under the condition that various modifications or changes being made by those skilled in the art without departing the scope of the invention as determined by the appended claims.

Claims

A thermal tripping mechanism of a surge protection device, comprising an elastic mechanism (105, 106; 205);
two voltage-sensitive resistors (103; 203) and one discharge tube (108; 204) forming a Y-shaped layout, the two voltage-sensitive resistors (103; 203) being directly or indirectly connected with the discharge tube (108; 204) by using a thermal fusing material;
the elastic mechanism (105, 106) comprising an elastic element (105; 205) and a sliding element (106), the elastic element (105; 205) driving the sliding element (106) to move by an elastic force;
wherein when the two voltage-sensitive resistors (103; 203) are both intact, the thermal fusing material is configured not to reach a fusing temperature, the two voltage-sensitive resistors (103; 203) and the discharge tube (108; 204) are configured to form a conductive path, and the elastic element (105; 205) is configured to be in an energy storage state; when at least one of the two voltage-sensitive resistors (103; 203) is degraded due to surge voltage, the thermal fusing material is configured to reach the fusing temperature, the elastic element (105; 205) is configured to release energy for driving the sliding element (106) to move, and the sliding element (106) is configured to move to cut off the conductive path;
wherein the two voltage-sensitive resistors (103; 203) are connected with the discharge tube (108; 204) through a connection piece (107);
the connection piece (107) comprises a conductive material, a first end of the connection piece (107) is provided with two first connection grooves (116), the two first connection grooves (116) are connected with pins (112) of the two voltage-sensitive resistors (103; 203) respectively, a second end of the connection piece (107) is provided with a second connection groove (118), the second connection groove (118) is connected with a pin of the discharge tube (108; 204), wherein the connection piece (107) is connected with at least one of the two voltage-sensitive resistors (103; 203) and the discharge tube (108; 204) through a thermal fusing material.
The thermal tripping mechanism of a surge protection device according to claim 1,
wherein the sliding element (106) is a sliding block, the sliding block is connected with the connection piece (107), the elastic element (105; 205) is configured to drive the sliding block to move by an elastic force.
The thermal tripping mechanism of a surge protection device according to claim 2, wherein
the connection piece (107) is elongated, the first end of the connection piece (107) is provided with a branch portion which extends laterally, the two first connection grooves (116) are semicircular and formed on the branch portion, the second connection groove (118) is circular, a sliding block hole (117) is formed between the first connection grooves (116) and the second connection groove (118);
the elastic element (105; 205) is a spring, one end of the spring is fixed on a shell (201) of the surge protection device, the other end of the spring is fixed on the sliding block, and the spring is energy-stored;
the sliding block is configured to move along a sliding chute in the shell (201) of the surge protection device, the sliding block is provided with a protrusion, the protrusion is placed in the sliding block hole of the connection piece (107);
the spring is configured to release energy and pull the sliding block to drive the connection piece (107) to move.
The thermal tripping mechanism of a surge protection device according to claim 1, wherein
the sliding element (106) is a sliding component, the sliding component is disposed within the shell (201) of the surge protection device and is configured to move in the shell (201) of the surge protection device;
the elastic element (105; 205) is connected with the sliding component, the elastic element (105; 205) is configured to drive the sliding component to move by an elastic force;
the pins (112) of the two voltage-sensitive resistors (103; 203) and the discharge tube (108; 204) are connected through a thermal fusing material;
the two voltage-sensitive resistors (103; 203) are fixedly assembled in the shell (201) of the surge protection device, the discharge tube (108; 204) is assembled on the sliding component and is configured to move along with the sliding component.
The thermal tripping mechanism of a surge protection device according to claim 4, wherein
the elastic element (105; 205) is a spring, one end of the spring is fixed within the shell (201) of the surge protection device, the other end of the spring is fixed on the sliding component, the spring is energy-stored;
a sliding groove is formed in the shell (201), the sliding component is configured to move along the sliding groove;
the spring is configured to release energy and push the sliding component to drive the discharge tube (108; 204) to move.
A surge protection device, comprising:
the thermal tripping mechanism of claim 1,

a shell (201), wherein a pin opening and a signal opening (111; 213) are provided in the outer contour of the shell (201);

wherein a first pin of the voltage-sensitive resistors (103; 203) and a first pin of the discharge tube (108; 204) are connected with insertion pins (104a, 104b; 214a, 214b), the insertion pins (104a, 104b; 214a, 214b) extend outside the shell (201) through a pin opening, a second pin of the voltage-sensitive resistors (103; 203) and a second pin of the discharge tube (108; 204) are directly or indirectly connected by using a thermal fusing material.
The surge protection device according to claim 6, wherein
the connection piece (107) is elongated, a first end of the connection piece (107) is provided with a branch portion which extends laterally, the two first connection grooves (116) are semicircular and formed on the branch portion, the second connection groove (118) is circular, a sliding block hole (117) is formed between the first connection grooves (116) and the second connection groove (118);
the elastic element (105; 205) is a spring and the sliding element (106) is a sliding block, the sliding block is configured to move along a sliding chute in the shell (201) of the surge protection device, the sliding block is provided with a protrusion, the protrusion is placed in the sliding block hole (117) of the connection piece (107); one end of the spring is fixed on a shell (201) of the surge protection device, the other end of the spring is fixed on the sliding block; the spring is energy-stored; when the spring releases energy, the spring is configured to pull the sliding block to drive the connection piece (107) to move.
The surge protection device according to claim 6, wherein
the sliding element (106) is a sliding component, the sliding component is disposed within the shell (201) of the surge protection device, a sliding chute is provided in the shell (201) and the sliding component is configured to move along the sliding chute;
the elastic element (105; 205) is connected with the sliding component, the elastic element (105; 205) is a spring, one end of the spring is fixed within the shell (201) of the surge protection device, the other end of the spring is fixed on the sliding component;
the pins (112) of the two voltage-sensitive resistors (103; 203) and the discharge tube (108; 204) are connected through a thermal fusing material;
the two voltage-sensitive resistors (103; 203) are fixedly assembled in the shell (201) of the surge protection device, the discharge tube (108; 204) is assembled on the sliding component and is configured to move along with the sliding component; the spring is energy-stored, and when the spring releases energy, the spring is configured to push the sliding component to drive the discharge tube (108; 204) to move.
The surge protection device according to claim 6, further comprising:
an indication component (101) assembled on the shell (201), the indication component (101) and the sliding element (106) forming a linkage mechanism;

an indication window (115) formed in the outer contour of the shell (201), the indication component (101) being assembled at a position corresponding to the indication window (115), wherein when the sliding element (106) is not driven by the elastic element (105; 205), the indication component (101) is configured to cover the indication window (115), when the sliding element (106) is driven by the elastic element (105; 205), the indication component (101) is configured to move away from the indication window (115).
The surge protection device according to claim 6, wherein
a dovetail groove (206) is formed in the bottom of the shell (201), the dovetail groove (206) is gradually narrowed from top to bottom;
the surge protection device is assembled in a U-shaped groove in a base, the U-shaped groove is provided with a positioning block (212) matched with the dovetail groove (206);
the positioning block (212) comprises a rod portion and an end portion, the end portion is larger than the rod portion, and the end portion forms an inclined guide surface with arc surfaces on both ends.