Oil return control valve group and crane telescopic system

Abstract

The invention belongs to the technical field of engineering machinery, and discloses an oil return control valve bank and a crane telescopic system.The oil return control valve bank comprises a unit back pressure valve arranged between a first side valve bank oil port and a second side valve bank oil port, and the unit back pressure valve comprises an overflow valve and an electromagnetic reversing valve which are arranged in parallel; and the electromagnetic reversing valve is used for connecting or disconnecting the first side valve group oil port and the second side valve group oil port. The crane telescopic system comprises a telescopic oil cylinder and an oil return control valve set, and the oil return control valve set is arranged in a rod cavity connecting oil way of the telescopic oil cylinder. According to the telescopic system of the crane, the oil return back pressure can be selectively set in the whole process during the working period of the oil cylinder so as to reduce power loss and system heating, the control response of the electromagnetic reversing valve is fast, the pressure building effect of the overflow valve is good, the control precision is accurate, and the operation performance of the telescopic system can be improved.

Description

Technical Field

[0001] The present application belongs to the technical field of engineering machinery, and specifically relates to an oil return control valve group and a crane telescopic system. Background Art

[0002] Various types of construction machinery generally have telescopic components with telescopic cylinders. For example, in a crane's boom telescopic system, it's often necessary to increase back pressure in the telescopic cylinder's rod chamber return oil circuit to ensure the boom can quickly and stably stop at the designated position during extension, deceleration, and stopping. Alternatively, back pressure can prevent the cylinder from automatically extending during rapid travel, sharp turns, or downhill maneuvers. Furthermore, in common pressurized plug-in pin telescopic systems, the pressure oil controlling the plug-in pins acts on the telescopic cylinder. When the cylinder is empty or the first few boom sections are performing the plug-in pin action with the boom light, the pressure oil may push the cylinder out, causing it to surge forward or fall backward. Increasing back pressure can effectively prevent this problem.

[0003] However, the crane's telescopic boom has a large mass and inertia, the hydraulic system has a large flow rate, and the required back pressure is high, resulting in large power loss due to back pressure during the boom extension process, severe system heat generation, affecting the life of system components, and failing to meet energy conservation and emission reduction requirements. Summary of the Invention

[0004] The main purpose of this application is to provide an oil return control valve group and a crane telescopic system to reduce the system's oil return energy loss.

[0005] To achieve the above-mentioned objectives, the present application provides a return oil control valve group, which includes a unit back pressure valve arranged between the oil port of the first side valve group and the oil port of the second side valve group. The unit back pressure valve includes a relief valve and an electromagnetic reversing valve arranged in parallel. The electromagnetic reversing valve is used to open or close the oil port of the first side valve group and the oil port of the second side valve group.

[0006] In some embodiments, the unit back pressure valve comprises:

[0007] The first unit back pressure valve comprises a first relief valve and a first electromagnetic reversing valve which are arranged in parallel between the oil port of the first side valve group and the oil port of the second side valve group;

[0008] The second unit back pressure valve includes a second overflow valve and a second electromagnetic reversing valve which are arranged in parallel between the oil port of the first side valve group and the oil port of the second side valve group.

[0009] In some embodiments, the opening pressure of the first relief valve is greater than the opening pressure of the second relief valve.

[0010] In some embodiments, the relief valve is an adjustable relief valve.

[0011] In some embodiments, the solenoid reversing valve is a two-position three-way valve, the reversing valve oil port on one side of the solenoid reversing valve is connected to the spring control chamber at the end of the relief valve, the first reversing valve working oil port on the other side is connected to the first side valve group oil port, and the second reversing valve working oil port is connected to the second side valve group oil port;

[0012] Among them, in the first valve position of the electromagnetic reversing valve, the working oil port of the first reversing valve and the working oil port of the second reversing valve are connected to each other, and the oil port of the reversing valve is cut off; in the second valve position of the electromagnetic reversing valve, the oil port of the reversing valve is connected to the working oil port of the first reversing valve, and the working oil port of the second reversing valve is cut off.

[0013] In some embodiments, the oil return control valve group further includes:

[0014] The one-way valve is arranged in the connecting oil circuit between the first side valve group oil port and the second side valve group oil port, and is configured to allow hydraulic oil to flow from the first side valve group oil port to the second side valve group oil port and cut off the reverse flow.

[0015] In some embodiments, the one-way valve is a check valve, a relief valve, or a cartridge valve.

[0016] In addition, the present application also provides a crane telescopic system, including a telescopic oil cylinder and the above-mentioned oil return control valve group, and the oil return control valve group is arranged in the rod chamber connecting oil circuit of the telescopic oil cylinder.

[0017] In some embodiments, the crane telescoping system includes a controller configured to:

[0018] Determining that the telescopic oil cylinder is in a high-speed extension state;

[0019] Controlling the electromagnetic reversing valve to switch to the conducting position to conduct the oil circuit connecting the rod chamber;

[0020] Determining that the telescopic oil cylinder is in a low-speed extension state in the oil cylinder;

[0021] Control the electromagnetic reversing valve to switch to the cut-off position.

[0022] In some embodiments, the controller is further configured to:

[0023] Determining that the telescopic oil cylinder is in a pin insertion and removal state;

[0024] The electromagnetic reversing valve is controlled to switch to the cut-off position.

[0025] In the crane telescopic system of the present application and the return oil control valve group used therein, the return oil control valve group includes a unit back pressure valve arranged between the oil ports of the valve group on both sides. The unit back pressure valve includes a relief valve and an electromagnetic reversing valve arranged in parallel. The electromagnetic reversing valve is used to conduct or cut off the oil ports of the valve group on both sides. In this way, the hydraulic return oil can return without back pressure when the electromagnetic reversing valve is in the conducting state, or return through the relief valve to overcome back pressure when the electromagnetic reversing valve is in the cut-off state. Therefore, during the operation of the oil cylinder, the return oil back pressure can be selectively set throughout the entire process to reduce power loss and system heating. In addition, the control response of the electromagnetic reversing valve is fast, the pressure building effect of the relief valve is good, and the control accuracy is accurate, which can improve the operating performance of the telescopic system. When the solenoid valve fails, the hydraulic oil in the rod chamber can return to the oil tank through the relief valve, and the hydraulic oil will not be blocked and cause damage to the oil cylinder.

[0026] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present application but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0028] Figure 1 、 Figure 2 They are respectively the hydraulic principle diagrams of the crane telescopic system of the prior art;

[0029] Figure 3 This is a hydraulic principle diagram of an oil return control valve group according to a specific embodiment of the present application;

[0030] Figure 4 This is a schematic diagram of the force analysis when the telescopic cylinder is extended with load;

[0031] Figure 5 It is a hydraulic principle diagram of a crane telescopic system according to a specific embodiment of the present application.

[0032] Description of Figure Numbers:

[0033] 1 Hydraulic oil tank 2 Main pump

[0034] 3 Main valve 4 Balancing valve

[0035] 5 Telescopic cylinder 6 Switching valve

[0036] 7 Latch mechanism 8 Oil return control valve group

[0037] 9 Auxiliary valve 10 Auxiliary pump

[0038] 11 Engine 12 Back pressure valve assembly

[0039] 81 First relief valve 82 First solenoid reversing valve

[0040] 83 Second electromagnetic reversing valve 84 Second relief valve

[0041] 83 One-way valve L0 Rodless chamber oil supply line

[0042] L1 Oil passage connecting the rodless cavity L2 Oil passage connecting the rod cavity DETAILED DESCRIPTION

[0043] The following describes the specific embodiments of the present application in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0044] The oil return control valve group and the crane telescopic system according to the present application are described below with reference to the accompanying drawings.

[0045] Figure 1 、 Figure 2 Two methods of increasing the back pressure of the rodless cavity return oil circuit of the existing crane telescopic system are respectively demonstrated. Figure 1 In the diagram, backpressure valve assembly 12 consists of multiple parallel relief valves to build up backpressure. During the boom extension process, the hydraulic oil in the rod chamber of the telescopic cylinder 5 must overcome the backpressure and return to the hydraulic oil tank 1. However, backpressure exists throughout the entire circuit during the extension process, typically reaching several MPa. Due to the large telescopic flow rate, power loss is severe, the system generates high heat, and this affects operating efficiency and reduces the service life of hydraulic components.

[0046] exist Figure 2 In the back pressure valve group 12, the back pressure valve is composed of a logic valve, a solenoid valve and a relief valve. According to actual needs, the opening and closing of the logic valve is controlled by the solenoid valve gaining and losing power. When the solenoid valve is not energized, the circuit establishes back pressure. When it is energized, there is no back pressure. Similarly, due to the large system flow, high fluid resistance in the return oil circuit, and high failure rate of the solenoid valve, there is a delay in the opening and closing of the logic valve, which will lead to poor pressure building effect in the return oil circuit. There is pressurized oil between the rod chamber of the telescopic cylinder 5 and the logic valve, which affects the closing of the balance valve. The telescopic start and stop action is delayed, and the cylinder cannot be accurately stopped at the specified position, affecting the action of the plug-in pin and causing the cylinder to rush forward. In severe cases, the cylinder may rush out of the boom, causing a major safety accident.

[0047] In view of this, the present application discloses a novel oil return control valve group 8. Figure 3 In a specific embodiment shown, different from Figure 1 、 Figure 2The back pressure valve group 12 shown, the return oil control valve group 8 includes a unit back pressure valve arranged between the first side valve group oil port A and the second side valve group oil port B, the unit back pressure valve includes a relief valve and an electromagnetic reversing valve arranged in parallel, the electromagnetic reversing valve is used to open or close the first side valve group oil port A and the second side valve group oil port B.

[0048] There can be one or more unit backpressure valves. Each unit backpressure valve, controlled by a solenoid, can open or close the connection between the two valve group oil ports. When the two valve group oil ports are connected, there is no backpressure between them. However, when the solenoid closes the connection between the two valve group oil ports, the hydraulic oil can only flow through the relief valve between the two valve group oil ports, resulting in overflow backpressure. Therefore, the unit backpressure valve, consisting of a relief valve and a solenoid reversing valve in parallel, can control the return oil backpressure, and the solenoid control has no switching delay or action lag.

[0049] In this embodiment, Figure 3 The unit back pressure valve in may include:

[0050] The first unit back pressure valve includes a first relief valve 81 and a first electromagnetic reversing valve 82 which are arranged in parallel between the first side valve group oil port A and the second side valve group oil port B;

[0051] The second unit back pressure valve includes a second relief valve 84 and a second electromagnetic reversing valve 83 which are arranged in parallel between the first side valve group oil port A and the second side valve group oil port B.

[0052] It can be seen that the return oil control valve group 8 as an example may include two unit back pressure valves arranged in parallel. Of course, more unit back pressure valves can be connected in parallel. Whether the first electromagnetic reversing valve 82 or the second electromagnetic reversing valve 83 is controlled, the connecting oil circuit between the first side valve group oil port A and the second side valve group oil port B can be controlled to generate back pressure. The control response of the electromagnetic reversing valve is fast, the pressure building effect of the relief valve is good, and the control accuracy is accurate. Figure 5 When the hydraulic system is used, the telescopic cylinder 5 can be decelerated and stopped smoothly, thereby reducing the failure rate of the plugging and pulling pins and effectively improving work efficiency and safety.

[0053] exist Figure 1 In the telescopic hydraulic system, the return oil circuit of the telescopic cylinder 5 has back pressure throughout the entire process, and the power loss caused by the back pressure is large. In its crane telescopic system, the high-speed time period of the cylinder extension and retraction accounts for a relatively high proportion. The use of the return oil control valve group 8 of the present application can make the return oil circuit free of back pressure when the telescopic cylinder 5 is extended at high speed, greatly reducing power loss and system heating, and improving the service life of hydraulic components.

[0054] exist Figure 2In the telescopic hydraulic system, when the telescopic cylinder 5 stops extending, the hydraulic oil in the return oil circuit returns to the hydraulic oil tank 1 without hindrance, which will not cause pressure to accumulate between the balance valve 4 and the back pressure valve group 12, resulting in a balance valve mis-opening failure, and prevent the telescopic cylinder 5 from automatically rushing forward and falling back during the insertion and removal of the pin in the center channel. In the event of a solenoid valve failure, Figure 5 The hydraulic oil in the rod chamber of the oil cylinder can return to the oil tank through the relief valve, and the hydraulic oil will not be blocked and cause damage to the oil cylinder.

[0055] When the oil return control valve group 8 includes a plurality of unit back pressure valves arranged in parallel, that is, a plurality of overflow valves arranged in parallel, for example Figure 3 The shown structure includes a first relief valve 81 and a second relief valve 84. For example, the opening pressure of the first relief valve 81 can be set to be greater than the opening pressure of the second relief valve 84. In this way, the flow rate required by the crane is generally large, and the flow rate of ordinary relief valves is relatively small. Figure 3 As shown, two relief valves are set and the opening pressures are set to different levels. The small-flow, low-speed hydraulic oil in the rod chamber connecting oil circuit L2 (the return oil circuit at this time) can pass through the relief valve with a small opening pressure. The large-flow hydraulic oil flows through the two relief valves at the same time, making the opening and closing more stable and the control effect better.

[0056] It should be noted that the opening pressure of each relief valve can be fixed or an adjustable relief valve can be used to adjust the pressure to suit different crane types and working conditions.

[0057] In this embodiment, the electromagnetic reversing valve adopts Figure 3 In the illustrated two-position, three-way valve, namely, the first solenoid directional valve 82 or the second solenoid directional valve 83, the directional valve oil port C0 on one side of the solenoid directional valve is connected to the spring control chamber at the end of the relief valve (e.g., the first relief valve 81). The first directional valve working oil port C1 on the other side is connected to the first-side valve group oil port A, and the second directional valve working oil port C2 is connected to the second-side valve group oil port B. In the first valve position of the solenoid directional valve (the upper position shown in the figure), the first directional valve working oil port C1 and the second directional valve working oil port C2 are connected to each other, and the directional valve oil port C0 is blocked. In the second valve position of the solenoid directional valve (the lower position shown in the figure), the directional valve oil port C0 is connected to the first directional valve working oil port C1, and the second directional valve working oil port C2 is blocked.

[0058] This two-position three-way solenoid valve has the simplest structure and fast switching control response. The spring control chamber (or spring chamber for short) at the end of the first relief valve 81 is connected to the reversing valve oil port C0. When the first solenoid reversing valve 82 is disconnected, the spring control chamber of the first relief valve 81 can quickly return oil, so that the pressure building effect of the relief valve is better.

[0059] In addition, the oil return control valve group 8 may also include a one-way valve 85, which is used to conduct one-way when the cylinder is retracted and cut off when the cylinder is extended. The one-way valve 85 is set in the connecting oil path between the first side valve group oil port A and the second side valve group oil port B, and is set to allow hydraulic oil to flow from the first side valve group oil port A to the second side valve group oil port B and cut off the reverse direction. Figure 3 As shown, the one-way guide valve 85 and the two unit back pressure valves are arranged in parallel, but the one-way flow direction of the hydraulic oil allowed by the one-way guide valve 85 is opposite to the overflow flow direction of the hydraulic oil allowed by the overflow valve in the unit back pressure valve.

[0060] The one-way valve 85 is set so that Figure 5 When pressurized oil enters the rod chamber of the telescopic cylinder 5, the pressurized oil pumped by the main pump 2 can be forward-directed to the one-way valve 85 in the oil return control valve assembly 8, thereby rapidly flowing to the rod chamber via the rod chamber connecting oil passage L2. Of course, those skilled in the art will appreciate that the one-way valve 85 is not limited to the one-way valve shown in the figure; it can also be a relief valve or a cartridge valve.

[0061] exist Figure 3 Based on the design of the oil return control valve group 8 shown in FIG, the present application also discloses a crane telescopic system, such as Figure 5 As shown, a crane telescopic system according to a specific embodiment may include a telescopic oil cylinder 5 and an oil return control valve group 8 . The oil return control valve group 8 is disposed in the rod chamber connecting oil path L2 of the telescopic oil cylinder 5 .

[0062] Usually, the crane boom is composed of multiple sections, and the extension and retraction of each section of the boom is driven by the telescopic cylinder 5. During the extension of the boom or the empty cylinder, the rodless chamber of the telescopic cylinder 5 is supplied with oil, and the rod chamber is returned with oil. When the cylinder slows down and stops, it is necessary to stop the cylinder at a specified position, and the next step of pulling and releasing the pin of the latch mechanism 7 is performed by controlling the switching valve 6. Generally, the telescopic cylinder 5 is large in size, requires a large flow rate, and has a large boom inertia. It is usually necessary to increase the back pressure in the rod chamber connecting oil circuit L2 to enable the cylinder to stop quickly and accurately. Figure 3 After the oil return control valve group 8 is installed, the power loss caused by back pressure can be reduced, the system heat can be reduced, and the working efficiency and safety can be improved.

[0063] See also Figure 5 When the telescopic cylinder 5 is extended, the engine 11 drives the main pump 2 to suck oil from the hydraulic oil tank 1. After the high-pressure oil is reversed by the main valve 3, it reaches the rodless chamber of the telescopic cylinder 5 through the balance valve 4 and the rodless chamber connecting oil circuit L1, pushing the hydraulic cylinder 5 to extend. At the same time, the hydraulic oil in the rod chamber connecting oil circuit L2 of the cylinder reaches the control valve group 8. The return oil can overcome the back pressure or return to the hydraulic oil tank 1 without back pressure.

[0064] The crane telescopic system may include a controller, which may be configured to:

[0065] Make sure that the telescopic cylinder 5 is in a high-speed extension state;

[0066] Control the electromagnetic reversing valve to switch to the conduction position to conduct the oil circuit connecting the rod chamber;

[0067] Make sure that the telescopic cylinder 5 is in the low-speed extension state in the cylinder;

[0068] Control the solenoid reversing valve to switch to the cut-off position.

[0069] Specifically, when the telescopic cylinder 5 is in a high-speed extension state, each solenoid reversing valve is controlled to switch to the conducting position to conduct the rod chamber connecting oil circuit, that is, the first solenoid reversing valve 82 and the second solenoid reversing valve 83 are energized, the solenoid valve is switched to the upper position, the spring chamber oil circuit of the first relief valve 81 and the second relief valve 84 is blocked, and the hydraulic oil of the rod chamber connecting oil circuit L2 passes through the first solenoid reversing valve 82 and the second solenoid reversing valve 83, and returns to the hydraulic oil tank 1 after passing through the main valve 3 under zero back pressure state, without power loss.

[0070] When the telescopic cylinder 5 is in a medium-to-low speed extension state, each solenoid reversing valve is controlled to switch to the cut-off position, that is, the first solenoid reversing valve 82 and the second solenoid reversing valve 83 are not energized, the solenoid valves remain in the lower position, and the hydraulic oil in the overflow valve spring chamber is connected to the return oil circuit. Since the first overflow valve 81 and the second overflow valve 84 are set with different spring forces (that is, opening pressures), two different back pressures are formed between the rod chamber of the telescopic cylinder 5 and the return oil control valve group 8. The low-pressure oil in the rod chamber connecting the oil circuit L2 passes through the first overflow valve 81 or the second overflow valve 84 with the set back pressure, passes through the main valve 3 and returns to the hydraulic oil tank 1, so that the hydraulic cylinder 5 can stop quickly and smoothly.

[0071] When the telescopic cylinder 5 retracts, the engine 11 drives the main pump 2 to suck oil from the hydraulic oil tank 1. The high-pressure oil is reversed by the main valve 3 and reaches the oil return control valve group 8. At this time, the first solenoid reversing valve 82 and the second solenoid reversing valve 83 are de-energized. The high-pressure oil passes through the one-way valve 85 to reach the balance valve 4 and acts on the rod chamber of the hydraulic cylinder, so that the hydraulic cylinder 5 opens smoothly and retracts.

[0072] Furthermore, the controller may be configured to:

[0073] Make sure that the telescopic cylinder 5 is in the pin insertion and removal state;

[0074] Control the solenoid reversing valve to switch to the cut-off position.

[0075] That is, when the telescopic cylinder 5 is inserting or removing the pin, since the pressure pushing the empty cylinder to extend is relatively small, the high-pressure oil supplied to the latch mechanism 7 through the central channel in the piston will act on the telescopic cylinder 5, causing the cylinder to extend forward. At this time, the first solenoid reversing valve 82 and the second solenoid reversing valve 83 are de-energized, and the first relief valve 81 and the second relief valve 84 have spring force, forming two different back pressures between the rod chamber of the telescopic cylinder and the return oil control valve group 8, preventing the cylinder from extending forward, which helps to quickly and accurately complete the pin insertion and removal process.

[0076] When the crane is traveling on the road, if there are unexpected situations such as excessive speed, downhill driving, sharp turns, etc., if the solenoid valve is not energized, the spring force set by the first relief valve 81 and the second relief valve 84 will form back pressure in the oil return line, which can prevent the oil cylinder from extending and play a safety protection role.

[0077] In addition, a large-sized hydraulic cylinder 5 can also be equipped with an auxiliary pump 10 outside the main pump 2. The auxiliary pump 10 pumps hydraulic oil, which is controlled by the auxiliary valve 9 and pumped into the rodless chamber of the cylinder through the rodless chamber supplementary oil circuit L0 to assist in driving the piston to extend.

[0078] At present, as the tonnage of cranes is getting bigger and bigger, in order to increase the weight and lifting height of the boom, the boom body is generally enlarged, and the super lift, auxiliary arm, tower arm and other configurations are added, which puts a great test on the safety of the telescopic cylinder. Figure 4 As shown in the figure, when a hydraulic cylinder extends a load, if there is no back pressure in the return oil circuit, the rodless chamber pressure P = F / A1, where F is the load and A1 is the cross-sectional area of the rodless chamber. At this point, if back pressure P1 is set in the return oil circuit, the rodless chamber pressure P = (F + P1 × A2) / A1, where A2 is the cross-sectional area of the rod chamber. If back pressure is present in the system, the cylinder extension pressure P increases, deteriorating the stability of the cylinder rod and potentially causing cylinder bending and damage, which can lead to serious safety accidents.

[0079] As can be seen, this application proposes a control method for a telescopic cylinder. This method can detect speed through methods such as the main valve handle opening. When the telescopic cylinder 5 is detected to be moving at high speed, the first solenoid reversing valve 82 and the second solenoid reversing valve 83 are energized, eliminating back pressure in the return oil circuit and reducing power loss. When the cylinder decelerates or stops, the first solenoid reversing valve 82 and the second solenoid reversing valve 83 are de-energized, creating back pressure between the rod chamber and the return oil control valve assembly 8, allowing the cylinder to stop quickly and smoothly. When the crane is traveling on the road, the solenoid valve is de-energized, creating back pressure between the rod chamber and the return oil control valve assembly 8, preventing the cylinder from extending due to inertia.

[0080] In the oil return control valve group 8, considering that the solenoid valve can pass a small flow rate and withstand low pressure, multiple solenoid valves can be set. When the cylinder is extended, oil enters the rodless chamber and oil returns to the oil rod chamber. The return oil circuit is low pressure, and the solenoid valve is switched under low pressure. The low-pressure oil in the rod chamber returns to the oil tank from the inside of the two groups of solenoid valves to meet the pressure and flow requirements of the solenoid valve; when the cylinder is retracted, oil enters the rod chamber, and the rod chamber is high pressure. The high-pressure oil acts on the cylinder from the one-way valve 85, and opens smoothly.

[0081] In the event of a solenoid valve failure, hydraulic oil can flow back to the tank through the relief valve, preventing damage to the cylinder due to pressure buildup. The relief valve's spring force is adjustable, allowing system parameters to be matched to different crane tonnages, ensuring high versatility. Figure 3 In the oil return control valve group 8 shown, the two overflow valves are set with different spring forces. When the system flow is large, the low-pressure oil in the rod chamber returns from the two sets of overflow valves at the same time. When the flow is small, the oil returns from the overflow valve with smaller spring force, which reduces the impact and makes the control smoother.

[0082] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0083] In this application, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0084] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0085] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. An oil return control valve group, characterized in that: The oil return control valve group (8) includes a unit back pressure valve arranged between the first side valve group oil port (A) and the second side valve group oil port (B), and the unit back pressure valve includes a relief valve and an electromagnetic reversing valve arranged in parallel, and the electromagnetic reversing valve is used to conduct or cut off the first side valve group oil port (A) and the second side valve group oil port (B).

2. The oil return control valve group according to claim 1, characterized in that: The unit back pressure valve comprises: The first unit back pressure valve comprises a first overflow valve (81) and a first electromagnetic reversing valve (82) arranged in parallel between the first side valve group oil port (A) and the second side valve group oil port (B); The second unit back pressure valve comprises a second overflow valve (84) and a second electromagnetic reversing valve (83) which are arranged in parallel between the first side valve group oil port (A) and the second side valve group oil port (B).

3. The oil return control valve group according to claim 2, characterized in that: The opening pressure of the first relief valve (81) is greater than the opening pressure of the second relief valve (84).

4. The oil return control valve group according to claim 1, characterized in that: The overflow valve is an adjustable overflow valve.

5. The oil return control valve group according to claim 1, characterized in that: The solenoid reversing valve is a two-position three-way valve, wherein the reversing valve oil port (C0) on one side of the solenoid reversing valve is connected to the spring control chamber at the end of the relief valve, the first reversing valve working oil port (C1) on the other side is connected to the first side valve group oil port (A), and the second reversing valve working oil port (C2) is connected to the second side valve group oil port (B); Wherein, in the first valve position of the electromagnetic reversing valve, the first reversing valve working oil port (C1) and the second reversing valve working oil port (C2) are connected to each other, and the reversing valve oil port (C0) is cut off; in the second valve position of the electromagnetic reversing valve, the reversing valve oil port (C0) is connected to the first reversing valve working oil port (C1), and the second reversing valve working oil port (C2) is cut off.

6. The oil return control valve assembly according to any one of claims 1 to 5, characterized in that: The oil return control valve group (8) further includes: A one-way valve (85) is provided in the connecting oil circuit between the first side valve group oil port (A) and the second side valve group oil port (B), and is configured to allow hydraulic oil to flow from the first side valve group oil port (A) to the second side valve group oil port (B) and to cut off the flow in the reverse direction.

7. The oil return control valve assembly according to claim 6, characterized in that: The one-way guide valve (85) is a one-way valve, a relief valve or a cartridge valve.

8. A crane telescopic system, comprising a telescopic cylinder (5), characterized in that: The crane telescopic system comprises an oil return control valve group (8) according to any one of claims 1 to 7, and the oil return control valve group (8) is arranged in the rod chamber connecting oil circuit (L2) of the telescopic cylinder (5).

9. The crane telescopic system according to claim 8, characterized in that: The crane telescoping system includes a controller configured to: Determining that the telescopic oil cylinder (5) is in a high-speed oil cylinder extension state; Controlling the electromagnetic reversing valve to switch to the conducting position to conduct the oil circuit connecting the rod chamber; Determining that the telescopic oil cylinder (5) is in a low-speed extension state in the oil cylinder; Control the electromagnetic reversing valve to switch to the cut-off position.

10. The crane telescopic system according to claim 9, wherein: The controller is further configured to: Determining that the telescopic oil cylinder (5) is in a pin insertion and removal state; The electromagnetic reversing valve is controlled to switch to the cut-off position.

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