An overload protection valve with limit switch

Abstract

An overload protection valve with a limit switch comprises a valve body, a transition plate assembly, a pilot cover plate assembly, and a one-way valve assembly. The top of the valve body is connected to the bottom of the transition plate assembly, the top of the transition plate assembly is connected to the bottom of the pilot cover plate assembly, the top of the pilot cover plate assembly is connected to the bottom of the valve seat assembly, the top of the valve seat assembly is connected to the bottom of the reversing valve, and the one-way valve assembly is inserted into the valve body. The top of the valve body is provided with an oil inlet and an oil return end, with the oil inlet end located behind the oil return end. One pressure measuring joint and two pressure measuring joints are provided on the left and right sides of the valve body, respectively. One pressure measuring joint is connected to the oil return end of the valve body, and the second pressure measuring joint is connected to the oil inlet end of the valve body. This design can prevent irreparable losses caused by the operator's mistaken operation of opening the overload protection valve, and the overload protection valve can be opened freely in an emergency.

Description

Technical Field

[0001] The invention relates to an improvement of an overload protection valve technology, belongs to the field of valves, and in particular to an overload protection valve with a limit switch. Background Art

[0002] When the crane winch hook is operating underwater, if the hook gets entangled underwater and causes overload, or other emergency situations may occur (such as emergency shutdown, main power failure or electrical control system failure, etc.), an overload protection valve is usually installed for protection. The overload protection valve is activated to unload the winch and actively abandon the rope, avoiding dragging of the crane due to underwater overload, which affects the safety of the crane.

[0003] However, in real-world use, the probability of such emergencies occurring is relatively low. If the operator misjudges the situation, the conventional overload protection valve will activate, causing the crane to abandon the rope. This is clearly uneconomical and unreliable. Furthermore, if the overload protection valve is activated solely due to a main power or electrical control system failure, it is clearly not intelligent enough and will not be able to open freely in an emergency.

[0004] A Chinese patent application with application number CN201711389138.5, filed on December 21, 2017, discloses an emergency overload protection system comprising a hydraulic pump, a reversing valve, a safety valve, a balancing valve, a hydraulic motor, a brake, a winch, and a fuel tank. The fuel tank, hydraulic pump, reversing valve, and hydraulic motor form an open circuit. A safety valve is provided at the hydraulic pump's oil outlet. The hydraulic motor drives the winch, and a balancing valve is provided at the hydraulic motor's oil port corresponding to the winch's rising action. The winch is equipped with a brake, a wire rope, and a sling. The system also includes an emergency overload protection valve, an oil replenishment source, a control oil source, a second shuttle valve, a third shuttle valve, a brake control valve, and a brake release oil source, disposed between the hydraulic pump and the reversing valve. However, this patent does not address the issue of the overload protection valve being unable to open freely in an emergency.

[0005] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of this patent application, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problem in the prior art that the overload protection valve cannot be freely opened in an emergency, and to provide an overload protection valve with a limit switch that can freely open the overload protection valve in an emergency.

[0007] To achieve the above objectives, the technical solution of the present invention is: an overload protection valve with a limit switch, the overload protection valve with a limit switch comprising a valve body, a transition plate assembly, a pilot cover plate assembly and a one-way valve assembly;

[0008] The top of the valve body is connected to the bottom of the transition plate assembly, the top of the transition plate assembly is connected to the bottom of the pilot cover plate assembly, the top of the pilot cover plate assembly is connected to the bottom of the valve seat assembly, the top of the valve seat assembly is connected to the bottom of the reversing valve, and the one-way valve assembly is inserted into the valve body;

[0009] The top of the valve body is provided with an oil inlet end and an oil return end in sequence. The oil inlet end is located on the rear side of the oil return end. One pressure measuring joint and two pressure measuring joints are respectively provided on the left and right sides of the valve body. One pressure measuring joint is connected to the oil return end of the valve body, and the second pressure measuring joint is connected to the oil inlet end of the valve body.

[0010] The transition plate assembly is flush with the left side of the pilot cover assembly, the valve seat assembly is axially extended along the right side of the pilot cover assembly, and the reversing valve is located on the top of the valve seat assembly and extends to the left.

[0011] The transition plate assembly includes a sensor, an extended push rod, a steel ball and a transition plate. One end of the sensor is installed on the valve body by a screw, and the other end of the sensor is connected to the left side of the transition plate by a screw. The inner cavity of the sensor is plugged into the left end of the extended push rod, and the right end of the extended push rod passes through the sensor and is connected to the steel ball. The steel ball is set on the transition plate.

[0012] The extended push rod includes a long rod and a connecting block. The left end of the long rod is plugged into the inner cavity of the sensor, one end of the long rod is connected to one end of the connecting block, the other end of the connecting block is connected to one end of the short rod, and the other end of the short rod is in contact with the steel ball.

[0013] A tensioning spring is arranged between the right side of the sensor and the left side of the connecting block, and the tensioning spring surrounds the outer side of the long rod.

[0014] The pilot cover plate assembly includes a pilot cover plate and a relief valve, the left side of the relief valve is plugged into the right side of the pilot cover plate, the valve seat assembly includes a valve seat and two relief valves, the left sides of the two relief valves are plugged into the right side of the valve seat, and the bottom of the reversing valve is mounted on the valve seat by screws.

[0015] The one-way valve assembly includes a valve sleeve, a valve core, a valve stem and a spring. An oil port is provided at the bottom of the valve sleeve, two oil ports are provided on the left and right sides of the valve sleeve, and three oil ports are provided on the top of the valve sleeve. A valve core is provided inside the valve sleeve, and the top of the inner cavity of the valve core is connected to the bottom of the valve stem. A spring is provided between the outside of the valve stem and the inner cavity of the valve core. The spring is located in the valve core and is arranged around the outside of the valve stem. The top of the valve stem is connected to the bottom of the pilot cover plate.

[0016] The first oil port is communicated with the oil inlet end of the valve body, the second oil port is communicated with the oil return end of the valve body, and the third oil port is communicated with the oil inlet end of the transition plate assembly.

[0017] The oil inlet end of the valve body is connected with the oil outlet of the variable pump, and the oil inlet of the variable pump is connected with the oil tank. The oil inlet end of the valve body is connected with the P1 port of the reversing valve through the first oil port and the third oil port. A sensor is provided on the one-way valve assembly. The oil return end of the valve body is connected with the T1 port of the reversing valve, and the P1 port of the reversing valve is connected with the oil tank through the second oil port and the oil return end of the valve body. The oil outlet of the variable pump is connected with the oil inlet of an overflow valve, and the oil outlet of an overflow valve is connected with the oil tank through the T port.

[0018] The P1 port of the reversing valve is connected to the A port, the A port of the reversing valve is connected to the oil inlet of the second relief valve, and the oil outlet of the second relief valve is connected to the oil tank through the T port.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. In an overload protection valve with a limit switch of the present invention, the top of the valve body is connected to the bottom of the transition plate assembly, the top of the transition plate assembly is connected to the bottom of the pilot cover assembly, the top of the pilot cover assembly is connected to the bottom of the valve seat assembly, the top of the valve seat assembly is connected to the bottom of the reversing valve, the one-way valve assembly is inserted into the valve body, a one-way valve is arranged in front of the valve body, when the one-way valve is actuated, the embedded valve stem actuates synchronously, a groove is arranged on the circumference of the valve stem, a steel ball is arranged on the sensor, and is placed in the groove of the valve stem, the extended push rod of the sensor presses the steel ball into the groove, and the one-way valve assembly is inserted into the valve body, and a one-way valve is arranged in front of the valve body, when the one-way valve is actuated, the embedded valve stem actuates synchronously, the circumference of the valve stem is provided with a groove, the sensor is provided with a steel ball, and is placed in the groove of the valve stem, and the extended push rod of the sensor presses the steel ball into the groove, and the one-way valve assembly is inserted into the valve body ... When the valve stem moves, the reaction force pushes the steel ball and the extended push rod to the left. At this time, the sensor collects the displacement information of the extended push rod and then feeds back the valve opening signal to the operator through the sensor, giving the operator time to react and identify the authenticity of the emergency situation and decide whether to activate the overload protection function. At the same time, the overload protection valve with a limit switch provided by the present invention can prevent the operator from opening the overload protection valve by mistake, causing irreparable losses. In an emergency, the overload protection valve can be opened freely. Therefore, this design is easy to use and has strong autonomy.

[0021] 2. In an overload protection valve with a limit switch of the present invention, the oil inlet end of the valve body is connected to the oil outlet of the variable pump, the oil inlet end of the variable pump is connected to the oil tank, the oil inlet end of the valve body is connected to the P1 port of the reversing valve through a one-way valve assembly, the one-way valve assembly is provided with a sensor, the oil return end of the valve body is connected to the T1 port of the reversing valve, the P1 port of the reversing valve is connected to the oil tank through the one-way valve assembly and the oil return end of the valve body, the oil outlet end of the variable pump is connected to the oil inlet end of a relief valve, the oil outlet end of a relief valve is connected to the oil tank through the T port, the reversing valve The valve's P1 port is connected to port A, and the reversing valve's A port is connected to the oil inlet of the second relief valve. The oil outlet of the second relief valve is connected to the oil tank via port T. During normal operation, the reversing valve's P port is blocked, and ports A and T are connected. The oil pressure entering the valve body is determined by the first relief valve. In an emergency, ports P and A are connected, and the oil pressure entering the valve body is determined by the second relief valve. The main oil circuit simultaneously flows through the internal flow channel in the valve body into the pilot cover assembly, then through the transition flow channel in the valve seat assembly, and finally into the P port of the reversing valve. Therefore, this design has a high safety factor and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the present invention.

[0023] Figure 2 It is a cross-sectional view of the present invention.

[0024] Figure 3 It is a top view of the valve body of the present invention.

[0025] Figure 4 It is a structural schematic diagram of the transition plate assembly in the present invention.

[0026] Figure 5 It is a structural schematic diagram of the one-way valve assembly in the present invention.

[0027] Figure 6 In the present invention Figure 2 side view.

[0028] Figure 7 It is the oil circuit connection diagram of the present invention.

[0029] In the figure: valve body 1, two pressure measuring joints 11, a pressure measuring joint 12, an oil return end 13, an oil inlet end 14, a transition plate assembly 2, a sensor 21, an extended push rod 22, a tensioning spring 23, a steel ball 24, a transition plate 25, a pilot cover assembly 3, a pilot cover 31, a relief valve 32, a relief valve oil inlet 321, a relief valve oil outlet 322, a valve seat assembly 4, a valve seat 41, two relief valves 42, two relief valve oil inlets 421, two relief valve oil outlets 422, a reversing valve 5, a check valve assembly 6, a valve sleeve 61, a valve core 62, a valve stem 63, a spring 64, two oil ports 65, one oil port 66, three oil ports 67, a variable pump 7, and an oil tank 8. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] See also Figures 1 to 7 , an overload protection valve with a limit switch, the overload protection valve with a limit switch includes a valve body 1, a transition plate assembly 2, a pilot cover plate assembly 3 and a one-way valve assembly 6;

[0032] The top of the valve body 1 is connected to the bottom of the transition plate assembly 2, the top of the transition plate assembly 2 is connected to the bottom of the pilot cover plate assembly 3, the top of the pilot cover plate assembly 3 is connected to the bottom of the valve seat assembly 4, the top of the valve seat assembly 4 is connected to the bottom of the reversing valve 5, and the one-way valve assembly 6 is inserted into the valve body 1;

[0033] The top of the valve body 1 is provided with an oil inlet end 14 and an oil return end 13 in sequence. The oil inlet end 14 is located on the rear side of the oil return end 13. A pressure measuring joint 12 and two pressure measuring joints 11 are respectively provided on the left and right sides of the valve body 1. One pressure measuring joint 12 is connected to the oil return end 13 of the valve body 1, and the two pressure measuring joints 11 are connected to the oil inlet end 14 of the valve body 1.

[0034] The transition plate assembly 2 is flush with the left side of the pilot cover assembly 3 , the valve seat assembly 4 is axially extended along the right side of the pilot cover assembly 3 , and the reversing valve 5 is located on the top of the valve seat assembly 4 and extends to the left.

[0035] The transition plate assembly 2 includes a sensor 21, an extended push rod 22, a steel ball 24 and a transition plate 25. One end of the sensor 21 is mounted on the valve body 1 by a screw, and the other end of the sensor 21 is connected to the left side of the transition plate 25 by a screw. The inner cavity of the sensor 21 is plugged into the left end of the extended push rod 22, and the right end of the extended push rod 22 passes through the sensor 21 and is connected to the steel ball 24. The steel ball 24 is set on the transition plate 25.

[0036] The extended push rod 22 includes a long rod 221 and a connecting block 222. The left end of the long rod 221 is plugged into the inner cavity of the sensor 21, one end of the long rod 221 is connected to one end of the connecting block 222, the other end of the connecting block 222 is connected to one end of the short rod 223, and the other end of the short rod 223 is in contact with the steel ball 24.

[0037] A tensioning spring 23 is provided between the right side of the sensor 21 and the left side of the connecting block 222 , and the tensioning spring 23 surrounds the outer side of the long rod 221 .

[0038] The pilot cover plate assembly 3 includes a pilot cover plate 31 and a relief valve 32, the left side of the relief valve 32 is plugged into the right side of the pilot cover plate 31, the valve seat assembly 4 includes a valve seat 41 and two relief valves 42, the left side of the two relief valves 42 is plugged into the right side of the valve seat 41, and the bottom of the reversing valve 5 is mounted on the valve seat 41 by screws.

[0039] The one-way valve assembly 6 includes a valve sleeve 61, a valve core 62, a valve stem 63 and a spring 64. An oil port 66 is provided at the bottom of the valve sleeve 61, two oil ports 65 are provided on the left and right sides of the valve sleeve 61, and three oil ports 67 are provided at the top of the valve sleeve 61. The interior of the valve sleeve 61 is cooperated with a valve core 62, the top of the inner cavity of the valve core 62 is connected to the bottom of the valve stem 63, and a spring 64 is provided between the outer side of the valve stem 63 and the inner cavity of the valve core 62. The spring 64 is located in the valve core 62 and is arranged around the outer side of the valve stem 63. The top of the valve stem 63 is connected to the bottom of the pilot cover plate 31.

[0040] The first oil port 66 is communicated with the oil inlet end 14 of the valve body 1 , the second oil port 65 is communicated with the oil return end 13 of the valve body 1 , and the third oil port 67 is communicated with the oil inlet of the transition plate assembly 2 .

[0041] The oil inlet end 14 of the valve body 1 is communicated with the oil outlet of the variable pump 7, and the oil inlet of the variable pump 7 is communicated with the oil tank 8. The oil inlet end 14 of the valve body 1 is communicated with the P1 port of the reversing valve 5 via the first oil port 66 and the third oil port 67. A sensor 21 is provided on the one-way valve assembly 6. The oil return end 13 of the valve body 1 is communicated with the T1 port of the reversing valve 5, and the P1 port of the reversing valve 5 is communicated with the oil tank 8 via the second oil port 65 and the oil return end 13 of the valve body 1. The oil outlet of the variable pump 7 is communicated with the oil inlet 321 of the overflow valve, and the oil outlet 322 of the overflow valve is communicated with the oil tank 8 via the T port.

[0042] The P1 port of the reversing valve 5 is connected to the A port, the A port of the reversing valve 5 is connected to the oil inlet 421 of the second overflow valve, and the oil outlet 422 of the second overflow valve is connected to the oil tank 8 through the T port.

[0043] The principle of the present invention is described as follows: the oil source of the main oil circuit enters the valve body 1 through the P port, first passes through the one-way valve assembly 6, and after the oil pressure overcomes the elastic force of the one-way valve spring 64, the valve core 62 moves upward, and the one-way valve assembly 6 opens. A part of the oil flows from the lower end of the one-way valve assembly 6 through the circumferential annular groove of the valve sleeve 61 into the outside of the one-way valve assembly 6, and the outside is connected to the T port of the valve body 1. The oil flows back to the oil tank through the T port. When the valve core 62 moves upward, it pushes the embedded valve stem 63 to move upward synchronously, and the other part of the oil enters the transition plate assembly 2 through the gap between the valve core 62 and the valve sleeve 61. The steel ball 24 contacts the extended push rod 22 and contacts the valve stem 63 in the one-way valve assembly 6. When the one-way valve assembly 6 is opened, its valve stem 63 moves upward. When the steel ball 24 and the extended push rod 22 are pushed to the left, the sensor 21 collects the signal through the left movement of the extended push rod 22, transmits it to the electronic control system, and feeds back information such as "the one-way valve assembly 6 is open" to the operator. The oil entering the transition plate assembly 2 flows into the inlet of a relief valve 32 through the internal flow channel of the pilot cover plate 31. During normal operation, the P1 port of the reversing valve 5 is blocked, and the A port is connected to the T port. At this time, the oil pressure entering the valve body 1 is determined by the relief valve 32. In an emergency, P is connected to the A port. At this time, the oil pressure entering the valve body 1 is determined by the second relief valve 42. At the same time, the main oil circuit flows into the pilot cover plate 31 through the internal flow channel in the valve body 1, and then flows into the P1 port of the reversing valve 5 through the transition flow channel in the valve seat 41.

[0044] Example 1:

[0045] An overload protection valve with a limit switch, the overload protection valve with a limit switch includes a valve body 1, a transition plate assembly 2, a pilot cover plate assembly 3 and a one-way valve assembly 6; the top of the valve body 1 is connected to the bottom of the transition plate assembly 2, the top of the transition plate assembly 2 is connected to the bottom of the pilot cover plate assembly 3, the top of the pilot cover plate assembly 3 is connected to the bottom of the valve seat assembly 4, the top of the valve seat assembly 4 is connected to the bottom of the reversing valve 5, and the one-way valve assembly 6 is inserted into the valve body 1; the top of the valve body 1 is sequentially provided with an oil inlet end 14 and an oil return end 13, the oil inlet end 14 is located at the rear side of the oil return end 13, and a pressure measuring joint 12 and two pressure measuring joints 11 are respectively provided on the left and right sides of the valve body 1, one pressure measuring joint 12 is connected to the oil return end 13 of the valve body 1, and the two pressure measuring joints 11 are connected to the oil inlet end 14 of the valve body 1, and the one pressure measuring joint 12 and the two pressure measuring joints 11 measure the return oil pressure and the oil inlet pressure respectively.

[0046] When in use, the oil source of the main oil circuit enters the valve body 1 through the P port, first passes through the one-way valve assembly 6, and the one-way valve assembly 6 is opened. A part of the oil flows from the lower end of the one-way valve assembly 6 to the outside of the one-way valve assembly 6, and the outside is connected to the T port of the valve body 1. The oil flows back to the oil tank through the T port. When the one-way valve assembly 6 is opened, the transition plate assembly 2 collects the signal and transmits it to the electronic control system. The oil entering the transition plate assembly 2 flows into the inlet of a relief valve 32 through the internal flow channel of the pilot cover plate assembly 3. During normal operation, the P1 port of the reversing valve 5 is blocked, and the A port is connected to the T port. At this time, the oil pressure entering the valve body 1 is determined by the relief valve 32. In an emergency, P is connected to the A port. At this time, the oil pressure entering the valve body 1 is determined by the second relief valve 42. At the same time, the main oil circuit flows into the pilot cover plate assembly 3 through the internal flow channel in the valve body 1, and then passes through the transition flow channel in the valve seat assembly 4 and finally flows into the P1 port of the reversing valve 5.

[0047] Example 2:

[0048] Example 2 is basically the same as Example 1, except that:

[0049] An overload protection valve with a limit switch, wherein the transition plate assembly 2 is flush with the left side of the pilot cover plate assembly 3, the valve seat assembly 4 is axially extended along the right side of the pilot cover plate assembly 3, and the reversing valve 5 is located on the top of the valve seat assembly 4 and extends to the left; the transition plate assembly 2 includes a sensor 21, an extended push rod 22, a steel ball 24 and a transition plate 25, one end of the sensor 21 is mounted on the valve body 1 by a screw, and the other end of the sensor 21 is connected to the left side of the transition plate 25 by a screw, the inner cavity of the sensor 21 is plugged into the left end of the extended push rod 22, and the extended push rod 22 is inserted into the inner cavity of the sensor 21. The right end of the rod 22 passes through the sensor 21 and is connected to the steel ball 24, and the steel ball 24 is set on the transition plate 25; the extended push rod 22 includes a long rod 221 and a connecting block 222, the left end of the long rod 221 is plugged into the inner cavity of the sensor 21, one end of the long rod 221 is connected to one end of the connecting block 222, the other end of the connecting block 222 is connected to one end of the short rod 223, and the other end of the short rod 223 is in contact with the steel ball 24; a tensioning spring 23 is provided between the right side of the sensor 21 and the left side of the connecting block 222, and the tensioning spring 23 is wrapped around the outside of the long rod 221.

[0050] Example 3:

[0051] Example 3 is basically the same as Example 2, except that:

[0052] An overload protection valve with a limit switch, the pilot cover plate assembly 3 includes a pilot cover plate 31 and a relief valve 32, the left side of the relief valve 32 is plugged into the right side of the pilot cover plate 31, the valve seat assembly 4 includes a valve seat 41 and two relief valves 42, the left side of the two relief valves 42 is plugged into the right side of the valve seat 41, the bottom of the reversing valve 5 is mounted on the valve seat 41 by screws, the one-way valve assembly 6 includes a valve sleeve 61, a valve core 62, a valve stem 63 and a spring 64, the bottom of the valve sleeve 61 is provided with an oil port 66, and two oil ports are provided on the left and right sides of the valve sleeve 61. Port 65, three oil ports 67 are opened on the top of the valve sleeve 61, and a valve core 62 is arranged inside the valve sleeve 61. The top of the inner cavity of the valve core 62 is connected to the bottom of the valve stem 63, and a spring 64 is arranged between the outer side of the valve stem 63 and the inner cavity of the valve core 62. The spring 64 is located in the valve core 62 and is arranged around the outer side of the valve stem 63. The top of the valve stem 63 is connected to the bottom of the pilot cover plate 31; the first oil port 66 is connected to the oil inlet end 14 of the valve body 1, the second oil port 65 is connected to the oil return end 13 of the valve body 1, and the third oil port 67 is connected to the oil inlet of the transition plate assembly 2.

[0053] Example 4:

[0054] Example 4 is basically the same as Example 3, except that:

[0055] An overload protection valve with a limit switch, the oil inlet end 14 of the valve body 1 is connected to the oil outlet of the variable pump 7, the oil inlet of the variable pump 7 is connected to the oil tank 8, the oil inlet end 14 of the valve body 1 is connected to the P1 port of the reversing valve 5 through the first oil port 66 and the third oil port 67, the one-way valve assembly 6 is provided with a sensor 21, the oil return end 13 of the valve body 1 is connected to the T1 port of the reversing valve 5, the P1 port of the reversing valve 5 is connected to the oil tank 8 through the second oil port 65 and the oil return end 13 of the valve body 1 The oil outlet of the variable pump 7 is connected to the oil inlet 321 of the first overflow valve, and the oil outlet 322 of the first overflow valve is connected to the oil tank 8 through the T port; the P1 port of the reversing valve 5 is connected to the A port, and the A port of the reversing valve 5 is connected to the oil inlet 421 of the second overflow valve, and the oil outlet 422 of the second overflow valve is connected to the oil tank 8 through the T port. Part of the oil entering the valve body 1 enters the oil inlet of the first overflow valve 32, and the other part of the oil enters the P1 port of the reversing valve 5. Since the reversing valve 5 is in this state, In the lower position, P is blocked, A and T ports are connected, and the oil can only pass through a relief valve 32. At this time, the pressure of the oil at port P is determined by the spring setting value of a relief valve 32. When the oil pressure at port P exceeds the spring setting value of the relief valve 1, the oil leaks from the oil outlet of a relief valve 32 and flows back to the oil tank 8 through the L port into the T port. When an emergency occurs and the valve body 1 needs to be opened, the operator operates the valve body 1 to reverse. At this time, the reversing valve 5 is in the upper position, and the P1 port of the reversing valve 5 is connected to the A port. The oil flows through the reversing valve 5 and enters the oil inlet of the second relief valve 42 from port A. Since the spring setting value of the second relief valve 42 is lower than that of the relief valve 1, the oil flows into the second relief valve 42. At this time, the pressure at port P is determined by the spring setting value of the second relief valve 42. When the oil pressure at port P exceeds the spring setting value of the second relief valve 42, the oil leaks from the oil outlet of the second relief valve 42 and flows into port T through port L and back to the oil tank 8. In this way, the hydraulic system is unloaded and the crane actively abandons the rope.

[0056] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed in the present invention should be included in the protection scope recorded in the claims.

Claims

1. An overload protection valve with a limit switch, characterized in that The overload protection valve with a limit switch comprises a valve body (1), a transition plate assembly (2), a pilot cover assembly (3) and a one-way valve assembly (6); The top of the valve body (1) is connected to the bottom of the transition plate assembly (2), the top of the transition plate assembly (2) is connected to the bottom of the pilot cover assembly (3), the top of the pilot cover assembly (3) is connected to the bottom of the valve seat assembly (4), the top of the valve seat assembly (4) is connected to the bottom of the reversing valve (5), and the one-way valve assembly (6) is inserted into the valve body (1); The top of the valve body (1) is provided with an oil inlet end (14) and an oil return end (13) in sequence. The oil inlet end (14) is located at the rear side of the oil return end (13). A pressure measuring joint (12) and two pressure measuring joints (11) are provided on the left and right sides of the valve body (1), respectively. The first pressure measuring joint (12) is connected to the oil return end (13) of the valve body (1), and the second pressure measuring joint (11) is connected to the oil inlet end (14) of the valve body (1). The transition plate assembly (2) includes a sensor (21), an extended push rod (22), a steel ball (24) and a transition plate (25), one end of the sensor (21) is mounted on the valve body (1) by a screw, the other end of the sensor (21) is connected to the left side of the transition plate (25) by a screw, the inner cavity of the sensor (21) is plugged into the left end of the extended push rod (22), the right end of the extended push rod (22) passes through the sensor (21) and is connected to the steel ball (24), and the steel ball (24) is arranged on the transition plate (25); The pilot cover plate assembly (3) includes a pilot cover plate (31) and a relief valve (32), the left side of the relief valve (32) is plugged into the right side of the pilot cover plate (31), the valve seat assembly (4) includes a valve seat (41) and two relief valves (42), the left sides of the two relief valves (42) are plugged into the right side of the valve seat (41), and the bottom of the reversing valve (5) is mounted on the valve seat (41) by screws; The one-way valve assembly (6) includes a valve sleeve (61), a valve core (62), a valve stem (63) and a spring (64). The bottom of the valve sleeve (61) is provided with an oil port (66), the left and right sides of the valve sleeve (61) are provided with two oil ports (65), and the top of the valve sleeve (61) is provided with three oil ports (67). The valve sleeve (61) is provided with a valve core (62) in cooperation with the interior of the valve sleeve (61). The top of the inner cavity of the valve core (62) is connected to the bottom of the valve stem (63). A spring (64) is provided between the outer side of the valve stem (63) and the inner cavity of the valve sleeve (62). The spring (64) is located in the valve core (62) and is arranged around the outer side of the valve stem (63). The top of the valve stem (63) is connected to the bottom of the pilot cover plate (31). The first oil port (66) is in communication with the oil inlet end (14) of the valve body (1), the second oil port (65) is in communication with the oil return end (13) of the valve body (1), and the third oil port (67) is in communication with the oil inlet end of the transition plate assembly (2); The oil inlet end (14) of the valve body (1) is connected to the oil outlet of the variable pump (7), the oil inlet of the variable pump (7) is connected to the oil tank (8), the oil inlet end (14) of the valve body (1) is connected to the P1 port of the reversing valve (5) through the first oil port (66) and the third oil port (67), a sensor (21) is provided on the one-way valve assembly (6), the oil return end (13) of the valve body (1) is connected to the T1 port of the reversing valve (5), the P1 port of the reversing valve (5) is connected to the oil tank (8) through the second oil port (65) and the oil return end (13) of the valve body (1), the oil outlet of the variable pump (7) is connected to the oil inlet (321) of the overflow valve, and the oil outlet (322) of the overflow valve is connected to the oil tank (8) through the T port; The P1 port of the reversing valve (5) is connected to the A port, the A port of the reversing valve (5) is connected to the oil inlet (421) of the second overflow valve, and the oil outlet (422) of the second overflow valve is connected to the oil tank (8) via the T port.

2. The overload protection valve with a limit switch according to claim 1, characterized in that: The transition plate assembly (2) is arranged flush with the left side of the pilot cover assembly (3), the valve seat assembly (4) is arranged to extend axially along the right side of the pilot cover assembly (3), and the reversing valve (5) is arranged to extend to the left side at the top of the valve seat assembly (4).

3. The overload protection valve with a limit switch according to claim 1, characterized in that: The extended push rod (22) includes a long rod (221) and a connecting block (222), the left end of the long rod (221) is plugged into the inner cavity of the sensor (21), one end of the long rod (221) is connected to one end of the connecting block (222), the other end of the connecting block (222) is connected to one end of the short rod (223), and the other end of the short rod (223) is in contact with the steel ball (24).

4. The overload protection valve with a limit switch according to claim 3, characterized in that: A tensioning spring (23) is provided between the right side of the sensor (21) and the left side of the connecting block (222), and the tensioning spring (23) surrounds the outside of the long rod (221).

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