An engineering vehicle implement control valve group with a balance valve switching function and a control method

Abstract

The application discloses an engineering vehicle accessory control valve group with a balance valve switching function and a control method, the valve group comprising a valve block, a first balance valve, a first electromagnetic reversing valve, a second balance valve and a second electromagnetic reversing valve arranged on the valve block, the first electromagnetic reversing valve being connected in parallel to both ends of the first balance valve to form a first bypass oil path, and the second electromagnetic reversing valve being connected in parallel to both ends of the second balance valve to form a second bypass oil path; when oil is fed, pressure oil enters the accessory oil cylinder through the internal check valve of the balance valve and the bypass oil path at the same time, so as to reduce the oil feeding pressure loss; the first electromagnetic reversing valve and the second electromagnetic reversing valve are configured to be synchronously powered on or synchronously powered off, so as to switch the oil return path; when powered on, the oil return is directly returned through the electromagnetic reversing valve, and when powered off, the oil return is throttled through the main throttle spool of the balance valve. The application takes into account the accessory rapid operation efficiency and the suspended operation safety, and has a compact structure.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology for engineering machinery, specifically to a control valve group and control method for engineering vehicle attachments with a balance valve switching function. Background Technology

[0002] Engineering vehicles are widely used in various construction fields such as infrastructure, municipal engineering, mining, agriculture, and forestry. The equipment is highly versatile and can switch between excavation, crushing, grabbing, and loading / unloading modes by changing different attachments such as hydraulic breakers, log grapples, clamping devices, and specialized buckets, achieving multi-purpose functionality and effectively reducing equipment investment and operating costs. Currently, the industry generally uses hydraulic drive to lock and unlock attachments, relying on attachment cylinders to complete the locking and unlocking operations.

[0003] To prevent attachments from slipping or falling due to their own weight during suspended operations and to ensure operational safety, existing hydraulic circuits typically include a balance valve. The balance valve's load-locking characteristic helps stabilize the attachment. However, existing technology has significant shortcomings: the balance valve in conventional valve assemblies is normally open and cannot be switched on / off according to working conditions. When changing attachments where safety requirements are lower but operating speed and energy efficiency are prioritized, the balance valve remains connected to the oil circuit, generating significant throttling resistance and back pressure. This results in sluggish attachment cylinder movement, low operating speed, increased energy loss in the hydraulic system, and a tendency for oil temperature to rise, accelerating component aging.

[0004] If the balance valve is removed to improve the data processing speed, the load safety lock function will be lost, the hovering reliability of the device will be greatly reduced, and it will be very easy to fall under heavy load and high-altitude conditions, posing a serious safety hazard.

[0005] Several attachment quick-change hydraulic systems have been disclosed in the prior art. For example, Chinese patent CN103967854A discloses an attachment quick-change control hydraulic system, which controls the disengagement of the attachment from the quick-change mechanism by energizing a solenoid directional valve and locks the attachment from the quick-change mechanism by de-energizing the solenoid directional valve. However, this solution only involves basic quick-change control and does not address the connection and bypass switching of the balance valve, nor does it solve the throttling resistance problem caused by the constant-open balance valve.

[0006] Chinese patent CN117967620A discloses a quick-change hydraulic system for attachments and a working machine. Its control components include a reversing element and a balancing element. The balancing element is located in the oil circuit between the reversing element and the actuator. When the actuator keeps the attachment in a locked state, the reversing element blocks the oil supply circuit, and the balancing element blocks the oil return circuit. However, the balancing element in this solution is fixedly connected and also lacks the function of on-demand bypass switching.

[0007] Therefore, existing attachment control valve assemblies cannot simultaneously balance operating speed and operating safety, and cannot well adapt to the usage needs of engineering vehicles with multiple working conditions and attachments. The industry urgently needs a new type of control valve assembly that can realize the switching of the working conditions of the balance valve. Summary of the Invention

[0008] This invention provides a control valve assembly and control method for engineering vehicle attachments with a balance valve switching function. It aims to resolve the technical contradiction in existing technologies where a constantly open balance valve leads to low work efficiency, while removing the balance valve poses a safety hazard, thus achieving a balance between work speed and safety. Furthermore, by employing a dual-path parallel oil supply method during oil inlet, the flow area is increased and oil inlet pressure loss is reduced, further improving system efficiency.

[0009] To achieve the above objectives, the present invention provides a control valve assembly for engineering vehicle attachments with a balance valve switching function, comprising a valve block, wherein the valve block is provided with a first balance valve, a first solenoid directional valve, a second balance valve, a second solenoid directional valve, a first oil port, a second oil port, a first working oil port, and a second working oil port, wherein: The first working port is used to communicate with the rodless chamber of the external attachment cylinder, and the second working port is used to communicate with the rod chamber of the external attachment cylinder. The first balance valve is connected to the first main oil line between the first oil port and the first working oil port, and the first solenoid directional valve is connected in parallel to both ends of the first balance valve to form the first bypass oil line. The second balance valve is connected to the second main oil line between the second working oil port and the second oil port, and the second solenoid directional valve is connected in parallel to both ends of the second balance valve to form the second bypass oil line. The first and second solenoid directional valves are configured to be energized or de-energized simultaneously. When oil is introduced, the pressurized oil simultaneously enters the rodless chamber of the external attachment cylinder through the internal check valve of the first balance valve and the first bypass oil passage, or simultaneously enters the rod chamber of the external attachment cylinder through the internal check valve of the second balance valve and the second bypass oil passage. In this way, the balance valve oil passage and the bypass oil passage form a dual parallel connection when oil is introduced, which effectively increases the oil inlet flow area, reduces the oil inlet pressure loss, and improves the cylinder action speed. When the first solenoid directional valve and the second solenoid directional valve are energized simultaneously, the hydraulic oil discharged from the external attachment cylinder during oil return will return directly through the return oil passage of the first solenoid directional valve or through the return oil passage of the second solenoid directional valve. When the first solenoid directional valve and the second solenoid directional valve are de-energized simultaneously, the hydraulic oil discharged from the external attachment cylinder during oil return returns through the main throttle valve core of the first balance valve or through the main throttle valve core of the second balance valve.

[0010] In the above scheme, regardless of whether the solenoid directional valve is energized or de-energized, the balance valve oil circuit and bypass oil circuit always supply oil in parallel during oil inlet, thereby increasing the oil inlet flow area and effectively reducing oil inlet pressure loss. The difference between the two working modes lies in the different return oil paths: when energized, the return oil goes directly back to the oil tank via the solenoid directional valve without throttling resistance; when de-energized, the return oil goes back via the main throttle valve core of the balance valve, generating stable back pressure to achieve load lock-up. Through this "dual parallel oil inlet, on-demand switching of return oil" setting, both efficiency and safety are achieved.

[0011] Furthermore, it also includes a first throttle plug and a second throttle plug. The first throttle plug is located at the control port of the first balance valve, and the second throttle plug is located at the control port of the second balance valve. Both the first and second throttle plugs are replaceable structures. By replacing the throttle plugs with different flow areas, the opening pressure and response speed of the corresponding first and second balance valves can be adjusted.

[0012] Furthermore, it also includes a third solenoid valve and a throttle valve. The third solenoid valve and the throttle valve are connected in series in the emergency oil circuit between the rodless chamber of the external attachment cylinder and the second oil port. When the third solenoid valve is energized and conducts, the hydraulic oil in the rodless chamber of the external attachment cylinder returns through the throttle valve, realizing the emergency lowering of the external engineering vehicle boom. Among them, the throttle valve is a replaceable structure. By changing the different flow areas of the throttle valve, the emergency lowering speed of the external engineering vehicle boom can be adjusted.

[0013] Furthermore, it also includes a first pressure testing connector, a second pressure testing connector, a third pressure testing connector, and a fourth pressure testing connector. The first pressure testing connector is installed on the oil inlet side of the first balancing valve and is used to detect the oil inlet pressure of the first balancing valve. The second pressure testing connector is installed on the oil outlet side of the first balancing valve and is used to detect the oil outlet pressure of the first balancing valve. The third pressure testing connector is installed on the oil outlet side of the second balancing valve and is used to detect the oil outlet pressure of the second balancing valve. The fourth pressure testing connector is installed on the oil inlet side of the second balancing valve and is used to detect the oil inlet pressure of the second balancing valve.

[0014] Furthermore, the first electromagnetic directional valve and the second electromagnetic directional valve are two-position three-way electromagnetic directional valves or two-position four-way electromagnetic directional valves.

[0015] Furthermore, the valve block is an integrated valve block, in which the first balancing valve, the first solenoid directional valve, the second balancing valve, the second solenoid directional valve, the third solenoid valve, the first throttle plug, the second throttle plug, the throttle valve, the first pressure test connector, the second pressure test connector, the third pressure test connector, and the fourth pressure test connector are all integrated and installed on the valve block, and are interconnected through the oil passage inside the valve block.

[0016] The present invention also provides a switching control method for an engineering vehicle attachment control valve group with a balance valve switching function as described above, comprising the following steps: The quick mode switching steps for assistive devices are as follows: A power signal is simultaneously sent to the first and second solenoid directional valves to simultaneously activate them; during oil inlet, pressurized oil simultaneously enters the rodless chamber of the external attachment cylinder through the internal check valve and the first bypass oil circuit of the first balance valve, or simultaneously enters the rod chamber of the external attachment cylinder through the internal check valve and the second bypass oil circuit of the second balance valve; during oil return, the hydraulic oil discharged from the external attachment cylinder returns directly through the return oil channel of the first solenoid directional valve, or directly through the return oil channel of the second solenoid directional valve, thus enabling rapid operation of the assistive device.

[0017] The steps for switching the attachment suspension operation mode are as follows: A de-energization signal is simultaneously sent to the first and second solenoid directional valves, causing them to shut off synchronously. During oil inlet, pressurized oil simultaneously enters the rodless chamber of the external attachment cylinder through the internal check valve and the first bypass oil passage of the first balance valve, or simultaneously enters the rod chamber of the external attachment cylinder through the internal check valve and the second bypass oil passage of the second balance valve. During oil return, the hydraulic oil discharged from the external attachment cylinder returns through the main throttle valve core of the first balance valve, or through the main throttle valve core of the second balance valve, generating stable back pressure to achieve stable locking and suspension of the attachment load.

[0018] Compared with existing technologies, this invention significantly increases the oil inlet flow area and effectively reduces oil inlet pressure loss by adopting a dual-path parallel oil supply method with a balance valve oil circuit and a bypass oil circuit, making the cylinder action faster and smoother. At the same time, by synchronously energizing and de-energizing two electromagnetic directional valves, the return oil path can be switched on demand. When energized, the return oil returns directly to the oil tank through the electromagnetic directional valve without throttling resistance, greatly improving the attachment's operating efficiency. When de-energized, the return oil returns through the main throttle valve core of the balance valve, generating stable back pressure to lock the load, effectively preventing the attachment from slipping or stalling. Thus, the same valve group balances the operating speed of the attachment during rapid operation and the safety of the attachment during suspended operation. In addition, the valve assembly integrates a replaceable throttle plug, which can be used to adjust the opening pressure and response speed of the balance valve by replacing the throttle plug with different flow areas. It is compatible with different weights and types of work attachments, making it highly versatile. It also integrates an independent emergency control circuit consisting of a third solenoid valve and a throttle valve. In case of equipment failure, the boom can be lowered in an emergency through the third solenoid valve, and the throttle valve can be replaced to adjust the lowering speed as needed to prevent rapid falls. It also integrates multiple pressure test connectors located on the oil inlet and outlet sides of each balance valve, which can detect the oil pressure at each key point in real time, making it easy to quickly determine the location and type of fault and simplify the troubleshooting process. The aforementioned quick-change control, balance protection, emergency circuit, and detection structure are all integrated and installed on the same valve block, resulting in a simple pipeline layout, reduced external pipelines and leakage points, convenient installation, and good operational stability. Furthermore, in the data rapid operation mode, the return oil goes directly back to the oil tank via the electromagnetic reversing valve, avoiding the throttling loss of the balance valve. Combined with the reduced inlet pressure loss due to the parallel connection of the two inlet oil paths, the overall energy consumption of the system is significantly reduced, heat generation is reduced, and the service life of the valve group and supporting hydraulic components is effectively extended. Attached Figure Description

[0019] Figure 1 This is an exploded view of the structure of a control valve group for an engineering vehicle attachment with a balance valve switching function according to the present invention; Figure 2 This is a hydraulic schematic diagram of a control valve group for an engineering vehicle attachment with a balance valve switching function, as described in this invention.

[0020] In the picture: 1. Valve block, 2. First balance valve, 3. First solenoid directional valve, 4. Second balance valve, 5. Second solenoid directional valve, 6. First oil port, 7. Second oil port, 8. First throttle plug, 9. Second throttle plug, 10. Third solenoid valve, 11. Throttling valve, 12. First pressure test connector, 13. Second pressure test connector, 14. Third pressure test connector, 15. Fourth pressure test connector. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way.

[0022] like Figures 1-2 As shown, this embodiment provides a control valve group for an engineering vehicle attachment with a balance valve switching function. It includes a valve block 1, and a first solenoid directional valve 3, a second solenoid directional valve 5, a first balance valve 2, a second balance valve 4, a third solenoid valve 10, a first throttle plug 8, a second throttle plug 9, a throttle valve 11, a plug 3, a first pressure test connector 12, a second pressure test connector 13, a third pressure test connector 14, and a fourth pressure test connector 15 integrated on the valve block 1. In this embodiment, the valve block 1 is an integrated valve block with multiple oil passages inside. Each hydraulic component is interconnected through the oil passages inside the valve block 1.

[0023] The valve block 1 is also provided with a first oil port 6, a second oil port 7, a first working oil port (not shown in the figure), and a second working oil port (not shown in the figure). The first working oil port is used to communicate with the rodless chamber of the external attachment cylinder, and the second working oil port is used to communicate with the rod-side chamber of the external attachment cylinder. The oil passage between the first oil port 6 and the first working oil port is the first main oil passage. The first balance valve 2 is connected in series on the first main oil passage, and the first solenoid directional valve 3 is connected in parallel to both ends of the first balance valve 2 to form the first bypass oil passage. The oil passage between the second working oil port and the second oil port 7 is the second main oil passage. The second balance valve 4 is connected in series on the second main oil passage, and the second solenoid directional valve 5 is connected in parallel to both ends of the second balance valve 4 to form the second bypass oil passage. The first solenoid directional valve 3 and the second solenoid directional valve 5 are two-position three-way solenoid directional valves or two-position four-way solenoid directional valves, and the two are configured to be energized or de-energized synchronously. The first balancing valve 2 and the second balancing valve 4 are both balancing valves with internal check valves and main throttle valve cores. The check valve allows the oil to flow freely in the oil inlet direction, and the main throttle valve core produces a throttling effect in the oil return direction and can adjust the opening degree according to the control pressure.

[0024] Regardless of whether the first solenoid valve 3 and the second solenoid valve 5 are energized or de-energized, the pressurized oil enters the attachment cylinder simultaneously through two paths during oil inlet, as follows: Path 1 (Balance Valve Oil Circuit): Pressurized oil enters the oil cylinder through the internal check valve of the balance valve; Path 2 (Bypass Oil Circuit): Pressurized oil enters the oil cylinder through the bypass channel of the solenoid directional valve.

[0025] The two paths are connected in parallel in the oil inlet direction, supplying oil to the cylinder together. Since the two paths are open at the same time, the oil inlet flow area is the sum of the flow area of ​​the one-way valve inside the balance valve and the flow area of ​​the solenoid directional valve. Compared with the single oil circuit supply scheme, this effectively increases the oil inlet flow area and significantly reduces the oil inlet pressure loss.

[0026] When the system enters the attachment rapid operation mode, the first solenoid directional valve 3 and the second solenoid directional valve 5 are simultaneously energized, and the oil inlet process is as follows: After the first solenoid directional valve 3 is energized, the first bypass oil circuit is opened. Pressurized oil enters the valve block 1 through the first oil port 6. Part of it enters the first working oil port through the internal check valve of the first balance valve 2, and the other part enters the first working oil port through the working channel of the first solenoid directional valve 3. The two oil paths merge and enter the rodless chamber of the external attachment cylinder. Because the oil inlet adopts a dual-path parallel connection, the flow area is significantly increased, the oil inlet pressure loss is greatly reduced, and the oil can quickly drive the cylinder piston rod to move in a high-flow, low-resistance state.

[0027] The oil return process is as follows: After the second solenoid directional valve 5 is energized synchronously, the second bypass oil circuit is opened. The hydraulic oil discharged from the rod chamber of the external attachment cylinder does not need to pass through the throttling control channel of the second balance valve 4. It can directly return to the oil tank through the return oil channel of the second solenoid directional valve 5 and the second oil port 7. There is no throttling resistance in the return oil process, which avoids the limitation of the cylinder action speed by the return oil back pressure caused by the throttling of the balance valve.

[0028] When the cylinder reverses its movement (i.e., pressurized oil enters the rod chamber and returns through the rodless chamber), the oil inlet and outlet flow is as follows: pressurized oil simultaneously enters the rod chamber through the internal check valve of the second balance valve 4 and the working channel of the second solenoid directional valve 5; during the return flow, the hydraulic oil discharged from the rodless chamber returns directly through the return channel of the first solenoid directional valve 3. The principle is the same and will not be elaborated further here.

[0029] In this mode, the oil inlet is supplied in parallel via two parallel oil inlets, and the return oil is directly returned to the oil tank via a solenoid directional valve. There is no throttling resistance in either the oil inlet or return, which significantly improves the cylinder's operating speed and greatly enhances the tool's working efficiency.

[0030] When switching to the attachment suspension operation mode, the first solenoid valve 3 and the second solenoid valve 5 are simultaneously de-energized. At this time, the oil inlet process is as follows: After the first solenoid directional valve 3 is de-energized, its working oil circuit is in a cut-off state. However, the internal passage of the first solenoid directional valve 3 still allows the oil to flow in one direction. After the pressurized oil flows into the valve block 1 from the first oil port 6, part of it enters the first working oil port through the internal check valve of the first balance valve 2, and the other part enters the first working oil port through the bypass passage of the first solenoid directional valve 3. After the two oil circuits merge, they enter the rodless chamber of the external attachment cylinder. The oil inlet also adopts a dual-circuit parallel connection, with a large flow area and small oil inlet pressure loss.

[0031] The oil return process is as follows: After the second solenoid directional valve 5 is de-energized, the second bypass oil circuit is disconnected, and the second balance valve 4 is connected to the second main oil circuit. The hydraulic oil discharged from the rod chamber of the external attachment cylinder cannot return directly through the second solenoid directional valve 5. It must flow through the main throttle valve core of the second balance valve 4 and return to the oil tank through the second oil port 7. Since the main throttle valve core of the second balance valve 4 can adjust the opening according to the control pressure, it generates a stable back pressure to counteract the weight of the attachment and prevent the cylinder from retracting rapidly due to the load.

[0032] When the cylinder moves in the reverse direction (i.e., the pressurized oil enters the rod chamber and returns from the rodless chamber), the oil inlet and outlet are as follows: When oil is inlet, the pressurized oil simultaneously enters the rod chamber through the internal check valve of the second balance valve 4 and the bypass channel of the second solenoid directional valve 5; when oil is outlet, the hydraulic oil discharged from the rodless chamber returns through the main throttle valve core of the first balance valve 2, generating a stable back pressure.

[0033] When the operating handle returns to the neutral position and the action command is cancelled, the main throttle valve cores of the first balance valve 2 and the second balance valve 4 quickly close, locking the return oil circuit and firmly locking the oil cylinder in the current position, thus achieving reliable hovering of the attachment.

[0034] In this mode, the parallel connection of the two oil inlets ensures the smoothness and response speed of the cylinder action, while the return oil is throttled by the balance valve to ensure stable locking of the load, thus balancing work efficiency and safety.

[0035] To further understand the working principle and beneficial effects of the present invention, a comparison is made between the attachment rapid operation mode and the attachment suspended operation mode, as shown in Table 1.

[0036]

[0037] As shown in Table 1, the control valve assembly provided by this invention maintains a dual-path parallel connection during oil inlet to increase the flow area and reduce pressure loss, while switching the return oil path achieves efficiency and safety mode switching. This approach is fundamentally different from the traditional solution of simply bypassing or connecting a balancing valve.

[0038] In some embodiments, the first throttle plug 8 is located at the control port of the first balance valve 2, and the second throttle plug 9 is located at the control port of the second balance valve 4. The first throttle plug 8 and the second throttle plug 9 are replaceable structures. By replacing the throttle plugs with different flow areas, the flow area of ​​the control oil circuit can be changed, thereby adjusting the opening pressure and response speed of the first balance valve 2 and the second balance valve 4 to adapt to different weights and types of working attachments.

[0039] In some implementations, when equipment malfunctions, the third solenoid valve 10 is energized and connected, opening the emergency oil circuit between the rodless chamber of the external attachment cylinder and the second oil port 7. The hydraulic oil in the rodless chamber can return via the throttle valve 11, enabling emergency lowering of the boom. The throttle valve 11 is replaceable; by replacing it with a throttle valve of different flow areas, the lowering speed of the boom can be adjusted to prevent a rapid fall.

[0040] In some embodiments, the valve assembly is further equipped with a first pressure testing connector 12, a second pressure testing connector 13, a third pressure testing connector 14, and a fourth pressure testing connector 15. The first pressure testing connector 12 is located on the oil inlet side of the first balancing valve 2 and is used to detect the inlet pressure of the first balancing valve 2; the second pressure testing connector 13 is located on the oil outlet side of the first balancing valve 2 and is used to detect the outlet pressure of the first balancing valve 2; the third pressure testing connector 14 is located on the oil outlet side of the second balancing valve 4 and is used to detect the outlet pressure of the second balancing valve 4; and the fourth pressure testing connector 15 is located on the oil inlet side of the second balancing valve 4 and is used to detect the inlet pressure of the second balancing valve 4.

[0041] Workers can use the aforementioned pressure testing connectors to monitor the oil pressure at key points in real time, identify fault locations, and facilitate rapid completion of maintenance work.

[0042] This embodiment also provides a switching control method for a control valve group of an engineering vehicle attachment with a balance valve switching function, the method including the following steps: The fast operation mode switching steps for attachments are as follows: A power signal is simultaneously sent to the first solenoid directional valve 3 and the second solenoid directional valve 5 to simultaneously activate them; during oil inlet, pressurized oil simultaneously enters the rodless chamber of the external attachment cylinder through the internal check valve and the first bypass oil passage of the first balance valve 2, or simultaneously enters the rod chamber of the external attachment cylinder through the internal check valve and the second bypass oil passage of the second balance valve 4; during oil return, the hydraulic oil discharged from the external attachment cylinder returns directly through the return oil passage of the first solenoid directional valve 3, or directly through the return oil passage of the second solenoid directional valve 5, thus achieving fast attachment operation. The steps for switching the attachment suspension operation mode are as follows: A de-energization signal is simultaneously sent to the first solenoid directional valve 3 and the second solenoid directional valve 5, causing them to shut off simultaneously. During oil inlet, pressurized oil simultaneously enters the rodless chamber of the external attachment cylinder through the internal check valve and the first bypass oil passage of the first balance valve 2, or simultaneously enters the rod chamber of the external attachment cylinder through the internal check valve and the second bypass oil passage of the second balance valve 4. During oil return, the hydraulic oil discharged from the external attachment cylinder returns through the main throttle valve core of the first balance valve 2, or through the main throttle valve core of the second balance valve 4, generating stable back pressure to achieve stable locking and suspension of the attachment load.

[0043] In summary, the control valve assembly provided by this invention, in the attachment's rapid operation mode, features dual parallel oil inlets to reduce pressure loss, and the return oil flows directly back to the oil tank via a solenoid directional valve without throttling resistance, significantly improving data processing speed. In the attachment's suspended operation mode, the dual parallel oil inlets still ensure smooth operation, and the return oil is throttled by a balance valve to generate back pressure, achieving load locking and anti-fall protection. These two modes can be flexibly switched according to working conditions, balancing efficiency and safety. Simultaneously, the emergency deployment mode provides a guarantee for safe handling in equipment failure situations.

[0044] The foregoing has provided a detailed description of the engineering vehicle attachment control valve group and control method with a balance valve switching function provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A control valve assembly for an engineering vehicle attachment with a balance valve switching function, characterized in that, The valve block (1) includes a first balance valve (2), a first solenoid directional valve (3), a second balance valve (4), a second solenoid directional valve (5), a first oil port (6), a second oil port (7), a first working oil port, and a second working oil port, wherein: The first working port is used to communicate with the rodless chamber of the external attachment cylinder, and the second working port is used to communicate with the rod chamber of the external attachment cylinder. The first balance valve (2) is connected to the first main oil line between the first oil port (6) and the first working oil port; The first electromagnetic directional valve (3) is connected in parallel to both ends of the first balance valve (2) and forms the first bypass oil circuit; The second balance valve (4) is connected to the second main oil line between the second working oil port () and the second oil port (7); The second electromagnetic directional valve (5) is connected in parallel to both ends of the second balance valve (4) and forms the second bypass oil circuit; The first electromagnetic reversing valve (3) and the second electromagnetic reversing valve (5) are configured to be energized or de-energized synchronously. When oil is introduced, the pressurized oil enters the rodless chamber of the external attachment cylinder through the internal check valve and the first bypass oil passage of the first balance valve (2), or enters the rod chamber of the external attachment cylinder through the internal check valve and the second bypass oil passage of the second balance valve (4). When the first solenoid directional valve (3) and the second solenoid directional valve (5) are energized simultaneously, the hydraulic oil discharged from the external attachment cylinder during oil return is directly returned through the oil return channel of the first solenoid directional valve (3) or directly returned through the oil return channel of the second solenoid directional valve (5). When the first solenoid directional valve (3) and the second solenoid directional valve (5) are de-energized simultaneously, the hydraulic oil discharged from the external attachment cylinder during oil return returns through the main throttle valve core of the first balance valve (2) or through the main throttle valve core of the second balance valve (4).

2. The engineering vehicle attachment control valve assembly with balance valve switching function according to claim 1, characterized in that, It also includes a first throttle plug (8) and a second throttle plug (9). The first throttle plug (8) is located at the oil inlet of the first balance valve (2), and the second throttle plug (9) is located at the oil inlet of the second balance valve (4). The first throttle plug (8) and the second throttle plug (9) are both replaceable structures. By replacing the throttle plugs with different flow areas, the opening pressure and response speed of the corresponding first balance valve (2) and second balance valve (4) can be adjusted.

3. The engineering vehicle attachment control valve assembly with balance valve switching function according to claim 1, characterized in that, It also includes a third solenoid valve (10) and a throttle valve (11), which are connected in series in the emergency oil circuit between the rodless chamber of the external attachment cylinder and the first or second oil port; When the third solenoid valve (10) is energized and turned on, the hydraulic oil in the rodless chamber of the external attachment cylinder returns through the throttle valve (11), realizing the emergency lowering of the external engineering vehicle boom.

4. The engineering vehicle attachment control valve assembly with balance valve switching function according to claim 3, characterized in that, The throttle valve (11) is a replaceable structure. By changing the flow area of ​​the throttle valve (11), the emergency lowering speed of the external engineering vehicle boom can be adjusted.

5. The engineering vehicle attachment control valve assembly with balance valve switching function according to claim 3, characterized in that, It also includes a first pressure testing connector, a second pressure testing connector, a third pressure testing connector, and a fourth pressure testing connector, wherein: The first pressure testing connector (12) is installed on the oil inlet side of the first balance valve (2) and is used to detect the oil inlet pressure of the first balance valve (2); The second pressure test connector (13) is installed on the oil line on the oil outlet side of the first balance valve (2) to detect the oil outlet pressure of the first balance valve (2); The third pressure test connector (14) is installed on the oil line on the oil outlet side of the second balance valve (4) and is used to detect the oil outlet pressure of the second balance valve (4); The fourth pressure test connector (15) is installed on the oil inlet side of the second balance valve (4) to detect the oil inlet pressure of the second balance valve (4).

6. The engineering vehicle attachment control valve assembly with balance valve switching function according to claim 1, characterized in that, The first electromagnetic reversing valve (3) and the second electromagnetic reversing valve (5) are two-position three-way electromagnetic reversing valves or two-position four-way electromagnetic reversing valves.

7. The engineering vehicle attachment control valve assembly with balance valve switching function according to claim 5, characterized in that, The valve block (1) is an integrated valve block. The first balance valve (2), the first solenoid directional valve (3), the second balance valve (4), the second solenoid directional valve (5), the third solenoid valve (10), the first throttle plug (8), the second throttle plug (9), the throttle valve (11), the first pressure test connector (12), the second pressure test connector (13), the third pressure test connector (14), and the fourth pressure test connector (15) are all integrated and installed on the valve block (1) and are interconnected through the oil passage inside the valve block (1).

8. A switching control method for a control valve group of an engineering vehicle attachment with a balance valve switching function as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The fast operation mode switching steps of the attachment are as follows: a power signal is sent to the first electromagnetic directional valve (3) and the second electromagnetic directional valve (5) to make the first electromagnetic directional valve (3) and the second electromagnetic directional valve (5) conduct synchronously; when oil is introduced, the pressure oil enters the rodless chamber of the external attachment cylinder through the internal check valve and the first bypass oil circuit of the first balance valve (2), or enters the rod chamber of the external attachment cylinder through the internal check valve and the second bypass oil circuit of the second balance valve (4); when oil is returned, the hydraulic oil discharged from the external attachment cylinder returns directly through the return oil channel of the first electromagnetic directional valve (3), or returns directly through the return oil channel of the second electromagnetic directional valve (5), so as to realize the fast operation of the attachment. The steps for switching the attachment suspended operation mode are as follows: a power failure signal is sent synchronously to the first electromagnetic directional valve (3) and the second electromagnetic directional valve (5) to simultaneously shut off the first electromagnetic directional valve (3) and the second electromagnetic directional valve (5); when oil is supplied, the pressurized oil simultaneously enters the rodless chamber of the external attachment cylinder through the internal check valve and the first bypass oil circuit of the first balance valve (2), or simultaneously enters the rod chamber of the external attachment cylinder through the internal check valve and the second bypass oil circuit of the second balance valve (4); when oil is returned, the hydraulic oil discharged from the external attachment cylinder returns through the main throttle valve core of the first balance valve (2), or returns through the main throttle valve core of the second balance valve (4), generating a stable back pressure to achieve stable locking and suspension of the attachment load.

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