A close contact checker

Abstract

The application discloses a close inspection device to solve the problems of complex structure and inconvenient maintenance in the prior art. The two swing assemblies of the close inspection device are rotationally connected with the lower part of a static contact point seat and respectively apply a pre-tightening force through elastic elements; the upper end and the lower end of the swing assembly are rotationally connected with a moving contact point and a roller respectively; the first gap and the second gap are located in the middle region of the upper surface of an indicating rod; when in close state, the two rollers are in a suspended state in the corresponding gaps, the rollers produce relative displacement with the horizontal movement of the indicating rod, start to roll and climb when sequentially contacting the corresponding inclined surfaces, and the corresponding swing assembly is forced to deflect over a critical position to drive the moving contact point to be disconnected with the static contact point. The close inspection device has no complex transmission structure from the indicating rod to the contact point group, is simple and direct in action, saves the space of a close inspection device accommodating cavity, and is convenient in replacement and installation of the contact point group and high in fault tolerance.

Description

Technical Field

[0001] This application relates to the field of railway signaling equipment technology, specifically to a railway contact inspection device. Background Technology

[0002] Railway signaling equipment is a crucial foundation for ensuring railway traffic safety and improving transportation efficiency. With the construction of high-speed railways and the continuous increase in train speeds, the technologies supporting these equipment, such as turnout switching machines and contact inspection devices, are also constantly evolving. The requirements for the safety of turnout switching at higher speeds, as well as the detection requirements for the contact and separation of turnout switch rails and core rails, are becoming increasingly stringent.

[0003] A railway turnout contact checker is a device used to inspect the contact and separation status between the turnout traction points. Originally, the contact checker was only used to check the contact status of the turnout, but later it was also added to check the degree of separation.

[0004] Taking the JM-A type turnout contact checker as an example, it is a mechanical-electric turnout contact checker that was standardized by China Railway in the 1980s and 1990s and is still widely used in ordinary speed sections. It is installed on the outside of the switch rail (or frog) and used in parallel with the switch machine. According to the specifications, the contact position stroke and the repulsion position stroke together constitute the complete detection system of the contact checker for the position of the switch rail / frog rail:

[0005] The current JM-A type tightness checker, from the indicator rod to the contact group, consists of a transmission chain composed of parts such as a quick-acting plate, compression spring, starting plate, adjusting plate, adjusting bolt, spline shaft, spline sleeve, bearing, mounting base, tension spring, crank shaft, and limit block. Its structure is complex, the parts are manufactured with high precision, there are many installation and adjustment steps, and human error is large, which brings great difficulties to on-site installation and use.

[0006] Patent document CN213168102U discloses an improved railway contact inspection device. Each contact group includes a stationary contact fixed on a base, an actuating plate rotatably mounted on the base, and a movable contact. The movable contact is movably mounted on the upper end of the actuating plate and corresponds to the stationary contact. The lower end of the actuating plate is provided with a roller that abuts against an indicator rod. A first spring connects the actuating plate and the base, and the first spring drives the roller to abut against the surface of the indicator rod. The surface of the indicator rod is provided with a contact indication notch and a repulsion indication notch at intervals. A quick-acting rod is slidably mounted inside the indicator rod. A second spring is provided between the quick-acting rod and the indicator rod. The second spring drives the quick-acting rod to move away from the repulsion indication notch. The elastic force of the second spring is less than that of the first spring. The quick-acting rod is provided with a boss that is accommodated in the contact indication notch. The boss and the contact indication notch and repulsion indication notch on the indicator rod are connected by a planar transition. When the close-fit indicator notch moves to the bottom of the corresponding roller, the roller presses against the bottom surface of the close-fit indicator notch under the force of the first spring. At this time, the actuating plate rotates relative to the base, and the moving contact at the top also moves relative to the base, so that the corresponding moving contact and stationary contact are connected. At this time, the other roller presses against the plane, and the inspector indicates the close-fit state. Similarly, when the repulsion indicator notch moves to the bottom of the corresponding roller, the roller presses against the bottom surface of the repulsion indicator notch. At this time, the other roller presses against the plane, and the inspector indicates the repulsion state, thus achieving the function of railway signal indication.

[0007] However, the solutions in the aforementioned patent documents require multiple sets of springs, quick-acting rods, and related mating structures, making the overall structure (especially the transmission structure) still quite complex and inconvenient to maintain. Summary of the Invention

[0008] This application provides a tight-fitting checker to solve the problems of complex overall structure and inconvenient maintenance in the prior art.

[0009] This application provides the following technical solution:

[0010] A contact inspection device includes a bottom shell and a top cover with a sealing cap disposed on the bottom shell. A receiving cavity is formed between the bottom shell and the top cover. The receiving cavity contains a stationary contact seat, two contact groups, and an indicator rod that extends laterally through the bottom shell. The contact groups include a stationary contact, a moving contact, a swing assembly, and a roller. The two stationary contacts of the stationary contact and the two moving contacts of the moving contact are arranged vertically. Its special feature is that:

[0011] The stationary contact is fixed to one side of the upper part of the stationary contact seat, and the swing assembly is rotatably connected to the lower part of the stationary contact seat and a preload is applied through an elastic element; the moving contact and the roller are rotatably connected to the upper and lower ends of the swing assembly, respectively; the movement of the moving contact and the roller of the two contact groups is relatively independent. The moving contact and the roller of the first contact group are respectively referred to as the first moving contact and the first roller, and the moving contact and the roller of the second contact group are respectively referred to as the second moving contact and the second roller.

[0012] The upper surface of the indicator rod has a first notch and a second notch on the front and rear sides of the central area, respectively. The first notch corresponds to the first roller, and the second notch corresponds to the second roller.

[0013] The first notch has a first plane and a first inclined plane, and the second notch has a second plane and a second inclined plane, wherein the length of the second plane is greater than that of the first plane, such that:

[0014] In the tight fit state, the first roller and the second roller are suspended in the first notch and the second notch respectively. Under the action of the pre-tightening force, the first moving contact and the corresponding stationary contact, and the second moving contact and the corresponding stationary contact, are reliably in contact.

[0015] As the indicator lever moves horizontally, the first and second rollers simultaneously displace relative to the indicator lever within the first and second notches, respectively. First, the first roller contacts the first inclined plane within the first notch and begins to roll and climb along the first inclined plane. The oscillating component of the first contact group is deflected by force, causing the first moving contact to disconnect from the corresponding stationary contact. After the first roller rolls and climbs to the upper surface of the indicator lever, it continues to roll, while the second roller remains suspended. During this process, the oscillating components of both the first and second contact groups maintain their current posture. Then, the second roller contacts the second inclined plane within the second notch and begins to roll and climb along the second inclined plane. The oscillating component of the second contact group is deflected by force, causing the second moving contact to disconnect from the corresponding stationary contact.

[0016] Alternatively, the elastic element may be a torsion spring or a tension spring.

[0017] Optionally, the swing assembly adopts a symmetrical frame structure, including a pair of parallel and relatively fixed side plates; the side plates include a main body area, an upper extension section and a lower extension section. Within the frame structure, the end of the upper extension section of the side plate is rotatably connected to the moving contact via a first connecting shaft, and the end of the lower extension section of the side plate is rotatably connected to the roller via a second connecting shaft; the center of the main body area serves as the rotation axis of the side plates, and the corresponding spindle is installed at the lower part of the stationary contact seat and passes through the pair of side plates; a third connecting shaft is also fixedly arranged between the pair of side plates, and in the vertical direction, the third connecting shaft is located between the first connecting shaft and the spindle; the torsion spring includes a spring body and an arc-shaped torsion arm, the spring body is sleeved on the spindle, and the arc-shaped torsion arm is hooked on the third connecting shaft.

[0018] Furthermore, the first connecting shaft, the second connecting shaft, and the spindle form an obtuse triangle in the vertical plane, with the central axis located at the obtuse angle point.

[0019] Furthermore, the first connecting axis, the third connecting axis, and the spindle form an obtuse triangle in the vertical plane, with the position of the third connecting axis being the obtuse angle point.

[0020] Optionally, the oscillating components of the first contact group and the oscillating components of the second contact group share the same spindle.

[0021] When the movement of the indicator rod reaches a predetermined first threshold, the first roller just contacts the first inclined surface within the first notch; when the movement of the indicator rod reaches a predetermined second threshold, the second roller just contacts the second inclined surface within the second notch.

[0022] Optionally, the other inclined planes, which are opposite to the first inclined plane and the second inclined plane respectively, are in the same position in the direction of the rod length.

[0023] Optionally, a scale is provided in the middle area of ​​the front or rear side of the indicator rod, a pointer pointing to the scale is fixedly provided in the accommodating cavity, and a detection unit for detecting the position indicated by the pointer is also provided.

[0024] For example, the pointer can be fixedly mounted on the housing of the stationary contact socket.

[0025] Compared with the prior art, this application has at least the following beneficial effects:

[0026] This application only requires two sets of single-sided contacts. Both swing components are rotatably connected to the lower part of the stationary contact seat and are preloaded by elastic elements. The upper and lower ends of the swing components are rotatably connected to the moving contact and the roller, respectively. The first notch and the second notch are both located in the middle area of ​​the upper surface of the indicator rod. In the close contact state, the two rollers are suspended in the corresponding notches. The length of the bottom plane of the second notch (second plane) is greater than the length of the bottom plane of the first notch (first plane). The initial position of the two rollers in the notch and the distance from the inclined plane are determined according to the first threshold and the second threshold, respectively. The rollers generate relative displacement as the indicator rod moves horizontally. The two rollers do not roll or bear force before contacting the corresponding inclined plane, ensuring that the contact group remains stably connected. When the two rollers contact the corresponding inclined plane in sequence, they begin to roll and climb. The corresponding swing component is deflected by force, causing its moving contact to disconnect from the stationary contact. After the roller rolls and climbs to the upper surface of the indicator rod, it continues to roll, and the swing component maintains its current posture. The current state (point rail / center rail position) can be characterized by the combination of on / off signals of these two sets of single-sided contacts; there is no complicated transmission structure from the indicator rod to the contact group, the action is simple and direct, and it also saves space in the housing cavity of the tight-fitting inspection device; moreover, the contact group is easier to replace and install, and has strong fault tolerance.

[0027] The swing assembly in this application adopts a symmetrical frame structure, including a pair of parallel and relatively fixed side plates. Within the frame structure, the end of the upper extension of the side plate is rotatably connected to the moving contact via a first connecting shaft, and the end of the lower extension of the side plate is rotatably connected to the roller via a second connecting shaft. The center of the main body area of ​​the side plate serves as the rotation axis of the side plate. A third connecting shaft is also provided between the rotation axis of the moving contact and the rotation axis of the side plate. A torsion spring is used as an elastic element to provide preload. The spring body of the torsion spring is sleeved on the spindle of the side plate, and the arc-shaped torsion arm is hooked onto the third connecting shaft. This allows for a simpler and more reliable structure to achieve smooth and accurate movement of the roller as it passes through the space above the bottom plane of the notch - the inclined plane of the notch - the upper surface of the indicator rod.

[0028] This application also provides a scale in the middle area of ​​the front or rear side of the indicator rod, and a pointer pointing to the scale is fixedly installed in the accommodating cavity (the pointer can be fixedly installed in the outer shell of the stationary contact seat). The horizontal movement position of the indicator rod can be directly characterized by detecting the position indicated by the pointer. As a redundancy scheme, the inspection results obtained from the inspection scheme based on the contact group can be mutually verified. Attached Figure Description

[0029] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0030] Figure 1 This is a schematic diagram of the overall structure of a contact patch inspector provided in one embodiment of this application;

[0031] Figure 2 This is a schematic diagram of a stationary contact seat and its related structures in one embodiment of this application;

[0032] Figure 3 for Figure 2 The illustrated embodiment shows a schematic diagram of a stationary contact seat unit corresponding to a contact group and its related structures.

[0033] Figure 4 for Figure 3 The internal structure diagram of the embodiment shown is shown.

[0034] Figure 5 for Figure 3 A front sectional view of the embodiment shown;

[0035] Figure 6 for Figure 3A front cross-sectional view of the swing component and its related structures in the illustrated embodiment;

[0036] Figure 7 for Figure 3 Axonometric view of the oscillating component and its related structures in the illustrated embodiment;

[0037] Figure 8 for Figure 7 A schematic diagram of the torsion spring in the illustrated embodiment;

[0038] Figure 9 This is a schematic diagram of the structure of the indicator rod in one embodiment of this application;

[0039] Figure 10 , Figure 11 This is a schematic diagram illustrating the working state at the same time in one embodiment of this application, wherein, Figure 10 This is a front (front side) view. Figure 11 This is a view of the rear (rear side).

[0040] Figure 12 , Figure 13 This is a schematic diagram of the working state of one embodiment of this application at different stereoscopic views at the same time.

[0041] Figure 14 This is a schematic diagram illustrating the principle of ruler indication.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Bottom shell; 2. Top cover; 3. Static contact point seat;

[0044] 4. Indicator rod; 401, First notch; 401a, First plane; 401b, First inclined plane; 402, Second notch; 402a, Second plane; 402b, Second inclined plane;

[0045] 5. Stationary contact; 500. Stationary contact; 6. Moving contact; 61. First moving contact; 62. Second moving contact; 600. Moving contact;

[0046] 7. Swing assembly; 700. Side plate; 701. First connecting shaft; 702. Second connecting shaft; 703. Third connecting shaft; 704. Spindle; 705. Torsion spring; 705a. Spring body; 705b. Arc-shaped torsion arm;

[0047] 8. Roller; 81. First roller; 82. Second roller;

[0048] 9. Ruler; 10. Pointer. Detailed Implementation

[0049] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] In the description of this application: unless otherwise stated, the terms "first," "second," "third," etc., are intended to distinguish the objects they refer to and do not have any special meaning in terms of technical connotation (e.g., they should not be construed as an emphasis on importance or order). Expressions such as "comprising," "including," and "having" also mean "not limited to" (certain units, components, etc.).

[0051] In one embodiment, such as Figures 1-13 As shown, the tight-fitting inspector includes a base shell 1 and an upper cover 2 with a sealing cap on the base shell 1. A receiving cavity is formed between the base shell 1 and the upper cover 2. The receiving cavity contains a stationary contact seat 3, two contact groups, and an indicator rod 4 that extends horizontally through the base shell 1. The contact groups include a stationary contact 5, a moving contact 6, a swing assembly 7, and a roller 8. The two stationary contacts 500 of the stationary contact 5 and the two moving contacts 600 of the moving contact 6 are arranged vertically. The stationary contact 5 is fixed to one side of the upper part of the stationary contact seat 3. The swing assembly... 7 is rotatably connected to the lower part of the stationary contact seat 3, and a preload is applied through an elastic element (specifically, a torsion spring, tension spring, etc.); the moving contact 6 and the roller 8 are rotatably connected to the upper and lower ends of the swing assembly 7, respectively; the movements of the moving contact 6 and the roller 8 of the two contact groups are relatively independent, wherein the moving contact 6 and the roller 8 of the first contact group are respectively referred to as the first moving contact 61 and the first roller 81, and the moving contact 6 and the roller 8 of the second contact group are respectively referred to as the second moving contact 62 and the second roller 82;

[0052] The front and rear sides of the middle area of ​​the upper surface of rod 4 (here, according to...) Figure 10 , Figure 11 The perspectives defined as "front" and "back" are respectively provided with a first notch 401 and a second notch 402, wherein the first notch 401 corresponds to the first roller 81 and the second notch 402 corresponds to the second roller 82;

[0053] The first notch 401 has a first plane 401a and a first inclined plane 401b, and the second notch 402 has a second plane 402a and a second inclined plane 402b, wherein the length of the second plane 402a is greater than that of the first plane 401a, such that:

[0054] In the close-fitting state, the first roller 81 and the second roller 82 are suspended in the first notch 401 and the second notch 402 respectively (that is, the first roller 81 and the second roller 82 maintain a gap with the first plane 401a and the second plane 402a respectively). Under the action of the pre-tightening force of the elastic element, the first moving contact 61 and the corresponding stationary contact 5, and the second moving contact 62 and the corresponding stationary contact 5 are reliably abutted.

[0055] As the indicator lever 4 moves horizontally, the first roller 81 and the second roller 82 simultaneously move relative to the indicator lever within the first notch 401 and the second notch 402, respectively (the rollers do not roll or bear force before contacting the inclined plane, ensuring that the contact group remains stably connected). Then, the first roller 81 contacts the first inclined plane within the first notch 401 and begins to roll and climb along the first inclined plane. The swing component of the first contact group is deflected by force, causing the first moving contact 61 to disconnect from the corresponding stationary contact. After the first roller 81 rolls and climbs to the upper surface of the indicator lever 4, it continues to roll, while the second roller 82 remains suspended. During this process, the swing components of the first and second contact groups maintain their current posture. Then, the second roller 82 contacts the second inclined plane within the second notch 402 and begins to roll and climb along the second inclined plane. The swing component of the second contact group is deflected by force, causing the second moving contact 62 to disconnect from the corresponding stationary contact.

[0056] When the movement of the indicator rod 4 reaches the predetermined first threshold, the first roller 81 just contacts the first inclined surface 401b in the first notch 401; when the movement of the indicator rod 4 reaches the predetermined second threshold, the second roller 82 just contacts the second inclined surface 402b in the second notch 402.

[0057] This embodiment only sets two sets of single-sided contacts. Both swing components are rotatably connected to the lower part of the stationary contact seat and are preloaded by elastic elements. The upper and lower ends of the swing components are rotatably connected to the moving contact and the roller, respectively. The first notch and the second notch are both located in the middle area of ​​the upper surface of the indicator rod. In the close contact state, the two rollers are suspended in the corresponding notches. The length of the bottom plane of the second notch (second plane) is greater than the length of the bottom plane of the first notch (first plane). The initial position of the two rollers in the notch and the distance from the inclined plane are determined according to the first threshold and the second threshold, respectively. The rollers generate relative displacement as the indicator rod moves horizontally. The two rollers do not roll or bear force before contacting the corresponding inclined plane, ensuring that the contact group remains stably connected. When the two rollers contact the corresponding inclined plane in sequence, they start to roll and climb. The corresponding swing component is deflected by force, causing its moving contact to disconnect from the stationary contact. After the roller rolls and climbs to the upper surface of the indicator rod, it continues to roll. The swing component maintains its current posture. The current state (point rail / center rail position) can be characterized by the combination of on / off signals of these two sets of single-sided contacts; there is no complicated transmission structure from the indicator rod to the contact group, the action is simple and direct, and it also saves space in the housing cavity of the tight-fitting inspection device; moreover, the contact group is easier to replace and install, and has strong fault tolerance.

[0058] Additionally, the other inclined surface (i.e., the inclined surface opposite to the first inclined surface 401b and the second inclined surface 402b respectively) Figure 9 , 13The two inclined planes near the right end shown in the figure can be set to be in the same position in the length direction of the rod 4.

[0059] Industry standards stipulate that if the gap between the switch rail and the stock rail is greater than 4mm, the turnout is considered not to have met the tight fit requirement. If the detected displacement corresponds to a gap exceeding 4mm, it indicates that the circuit is broken, and a "turnout not tight fit" warning is issued to the signaling system, prohibiting train passage. In this embodiment, the aforementioned first threshold of 4mm is the most critical parameter to ensure the safe and reliable operation of the turnout.

[0060] During the transition of a turnout from one position (e.g., center position) to another position (e.g., reverse position), the indicator rod is displaced as the switch rail moves. When the indicator rod displacement reaches 65mm, it usually indicates that the switch rail has moved to the vicinity of the target position. In this embodiment, the aforementioned second threshold is 65mm.

[0061] Taking a maximum stroke of 170mm for the indicator rod as an example, the first notch is a short notch, and the second notch is a long notch. When the indicator rod 4 is in its normal position, both contact groups are connected simultaneously, indicating a tight fit. As the indicator rod 4 is pulled out, when the first roller 81 contacts the inclined surface of the first notch of the indicator rod (i.e., the first inclined surface 401b), the indicator rod moves horizontally by 4mm. The first roller 81 begins to roll along the inclined surface, and its swing component is deflected by force, reliably disconnecting the first contact group. However, the second contact group remains connected. At this time, the contact group signal indicates that the switch rail is not in tight fit. When the indicator rod is pulled out by 65mm, the second roller 82 just contacts the inclined surface of the second notch of the indicator rod (i.e., the second inclined surface 402b). When the second roller 82 begins to roll along the inclined surface, its swing component is deflected by force, reliably disconnecting the second contact group as well. At this time, both the first and second contact groups are disconnected, indicating that the switch rail has moved to the vicinity of the target position.

[0062] In one embodiment, such as Figures 5-7 As shown, the swing assembly 7 adopts a symmetrical frame structure, including a pair of parallel and relatively fixed side plates 700. The side plate 700 includes a main body area, an upper extension section and a lower extension section. Within the frame structure, the end of the upper extension section of the side plate 700 is rotatably connected to the moving contact 6 through a first connecting shaft 701, and the end of the lower extension section of the side plate 700 is rotatably connected to the roller 8 through a second connecting shaft 702. The center of the main body area serves as the rotation axis of the side plate 700, and the corresponding spindle 704 is installed at the lower part of the stationary contact seat 3 and passes through the pair of side plates 700. A third connecting shaft 703 is also fixedly arranged between the pair of side plates 700. In the vertical direction, the third connecting shaft 703 is located between the first connecting shaft 701 and the spindle 704. The torsion spring 705 includes a spring body 705a and an arc-shaped torsion arm 705b. The spring body 705a is sleeved on the spindle 704, and the arc-shaped torsion arm 705b is hooked on the third connecting shaft 703.

[0063] from Figure 6 It can be seen that the first connecting shaft 701, the second connecting shaft 702 and the spindle 704 form an obtuse triangle in the vertical plane, with the central axis 704 at the obtuse angle point; the first connecting shaft 701, the third connecting shaft 703 and the spindle 704 also form an obtuse triangle in the vertical plane, with the third connecting shaft 703 at the obtuse angle point.

[0064] The swing assembly of this embodiment adopts a symmetrical frame structure, including a pair of parallel and relatively fixed side plates. Within the frame structure, the end of the upper extension of the side plate is rotatably connected to the moving contact via a first connecting shaft, and the end of the lower extension of the side plate is rotatably connected to the roller via a second connecting shaft. The center of the main body area of ​​the side plate serves as the rotation axis of the side plate. A third connecting shaft is also provided between the rotation axis of the moving contact and the rotation axis of the side plate. A torsion spring is used as an elastic element to provide preload. The spring body of the torsion spring is sleeved on the spindle of the side plate, and the arc-shaped torsion arm is hooked onto the third connecting shaft. This allows the roller to move smoothly and accurately when passing through the bottom plane of the notch, the inclined plane of the notch, and the upper surface of the indicator rod with a simpler and more reliable structure.

[0065] For a simpler structure, the oscillating component 7 of the first contact group and the oscillating component 7 of the second contact group can also share the same spindle 704.

[0066] In one embodiment, an additional inspection scheme can be added: such as Figure 14 As shown, a scale 9 is provided in the middle area of ​​the front or rear side of the indicator rod 4. A pointer 10 pointing downwards towards the scale is fixedly provided on the outer shell of the stationary contact seat 3. A detection unit for detecting the pointer's position is also provided. In this way, the current horizontal movement position of the indicator rod is directly characterized by detecting the pointer's position. As a redundancy scheme, the inspection results obtained can be mutually verified with those obtained by the contact group-based inspection scheme.

[0067] The detection unit used to detect the position indicated by the pointer can be triggered by a sensor or obtain its current position through real-time image capture and recognition. The specific technical means in this regard are conventional and will not be elaborated upon here.

[0068] The technical features of the above embodiments can be combined in any way (as long as there is no contradiction in the combination of these technical features). For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; these embodiments not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A tight-fitting inspection device, comprising a bottom shell (1) and a top cover (2) sealing the bottom shell (1), wherein a receiving cavity is formed between the bottom shell (1) and the top cover (2), and the receiving cavity is provided with a stationary contact seat (3), two contact groups, and an indicator rod (4) extending transversely through the bottom shell (1), wherein the contact group includes a stationary contact (5), a moving contact (6), a swing assembly (7), and a roller (8), wherein the two stationary contacts (500) of the stationary contact (5) and the two moving contacts (600) of the moving contact (6) are arranged vertically; characterized in that: The stationary contact (5) is fixed to the upper side of the stationary contact seat (3), and the swing assembly (7) is rotatably connected to the lower part of the stationary contact seat (3) and a preload is applied by an elastic element; the moving contact (6) and the roller (8) are rotatably connected to the upper and lower ends of the swing assembly (7), respectively; the movement of the moving contact (6) and the roller (8) of the two contact groups is relatively independent, wherein the moving contact (6) and the roller (8) of the first contact group are respectively referred to as the first moving contact (61) and the first roller (81), and the moving contact (6) and the roller (8) of the second contact group are respectively referred to as the second moving contact (62) and the second roller (82); The upper surface of the indicator rod (4) has a first notch (401) and a second notch (402) on the front and rear sides of the middle area, respectively. The first notch (401) corresponds to the first roller (81), and the second notch (402) corresponds to the second roller (82). The first notch (401) has a first plane and a first inclined plane, and the second notch (402) has a second plane and a second inclined plane, wherein the length of the second plane is greater than that of the first plane, such that: In the close-fitting state, the first roller (81) and the second roller (82) are suspended in the first notch (401) and the second notch (402) respectively. Under the action of the pre-tightening force, the first moving contact (61) and the corresponding stationary contact, and the second moving contact (62) and the corresponding stationary contact, are reliably in contact. As the indicator rod (4) moves horizontally, the first roller (81) and the second roller (82) simultaneously move relative to the indicator rod within the first notch (401) and the second notch (402), respectively. First, the first roller (81) contacts the first inclined plane within the first notch (401) and begins to roll and climb along the first inclined plane. The swing component of the first contact group is deflected by force, causing the first moving contact (61) to disconnect from the corresponding stationary contact. After the first roller (81) rolls and climbs to the upper surface of the indicator rod (4), it continues to roll, while the second roller (82) remains suspended. During this process, the swing components of the first and second contact groups maintain their current posture. Then, the second roller (82) contacts the second inclined plane within the second notch (402) and begins to roll and climb along the second inclined plane. The swing component of the second contact group is deflected by force, causing the second moving contact (62) to disconnect from the corresponding stationary contact.

2. The tightness checker according to claim 1, characterized in that: The elastic element is a torsion spring or a tension spring.

3. The tightness checker according to claim 2, characterized in that: The swing assembly (7) adopts a symmetrical frame structure, including a pair of parallel and relatively fixed side plates (700); the side plate (700) includes a main body area, an upper extension section and a lower extension section. Within the frame structure, the end of the upper extension section of the side plate (700) is rotatably connected to the moving contact (6) via a first connecting shaft (701), and the end of the lower extension section of the side plate (700) is rotatably connected to the roller (8) via a second connecting shaft (702); the center of the main body area serves as the pivot point of the side plate (700). The moving shaft and the corresponding spindle (704) are installed at the lower part of the stationary contact seat (3) and pass through a pair of side plates (700); a third connecting shaft (703) is also fixedly arranged between the pair of side plates (700), and the third connecting shaft (703) is located between the first connecting shaft (701) and the spindle (704) in the vertical direction; the torsion spring (705) includes a spring body and an arc-shaped torsion arm, the spring body is sleeved on the spindle (704), and the arc-shaped torsion arm is hooked on the third connecting shaft (703).

4. The tightness checker according to claim 3, characterized in that: The first connecting shaft (701), the second connecting shaft (702), and the spindle (704) form an obtuse triangle in the vertical plane, with the central axis (704) at the obtuse angle point.

5. The tightness checker according to claim 3, characterized in that: The first connecting shaft (701), the third connecting shaft (703), and the spindle (704) form an obtuse triangle in the vertical plane, wherein the position of the third connecting shaft (703) is the obtuse angle point.

6. The tightness checker according to claim 2, characterized in that: The oscillating component (7) of the first contact group and the oscillating component (7) of the second contact group share the same spindle (704).

7. The tightness checker according to claim 2, characterized in that: When the movement of the indicator rod (4) reaches the first threshold, the first roller (81) just contacts the first inclined surface in the first notch (401); when the movement of the indicator rod (4) reaches the second threshold, the second roller (82) just contacts the second inclined surface in the second notch (402).

8. The tightness checker according to claim 1, characterized in that: The other inclined planes, which are opposite to the first and second inclined planes respectively, are in the same position along the length of the rod (4).

9. The tightness checker according to claim 1, characterized in that: A scale (9) is provided in the middle area of ​​the front or rear side of the indicator rod (4), a pointer (10) pointing to the scale is fixedly provided in the accommodating cavity, and a detection unit for detecting the position indicated by the pointer is also provided.

10. The tightness checker according to claim 9, characterized in that: The pointer (10) is fixedly mounted on the outer shell of the stationary contact seat (3).

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