Control valve group, hydraulic system, reach crane and boom extension control method

Abstract

The present application relates to the field of hydraulic control technology, and specifically to a control valve group, a hydraulic system, a front crane, and a boom extension and retraction control method. The control valve group includes a first reversing valve and a second reversing valve, and the first reversing valve and the second reversing valve cooperate to enable the boom of the front crane to switch between different states. In the boom's no-load extended state, the first reversing valve is in the first working position and the second reversing valve is in the first working position. At the same time, the third working oil port of the first reversing valve is connected to the second oil inlet of the second reversing valve, so that the hydraulic oil in the rod chamber can flow through the first reversing valve through the second reversing valve and return to the third pipeline. The present application can cooperate with the first reversing valve and the second reversing valve to enable the hydraulic oil in the rod chamber to flow through the second reversing valve through the first reversing valve and return to the third pipeline. When the boom is no-load extended, the oil supply flow of the oil pump and the pressure loss of the pipeline are reduced, thereby saving working energy consumption.

Description

Technical Field

[0001] The present application relates to the field of hydraulic control technology, and in particular to a control valve group, a hydraulic system, a reach crane, and a boom extension and retraction control method. Background Art

[0002] Cranes are commonly used in construction machinery. The folding arm of a crane is controlled by a hydraulic control system to control the hydraulic cylinder to achieve the arm movement function.

[0003] In the existing technology, a reversing valve group is used to realize the extension and retraction of the boom telescopic cylinder, and then the folding and extension of the boom. However, when the boom is extended without load, there are problems such as large pump flow, high pressure loss in the system pipeline, and high energy consumption, which increases the energy consumption of the entire machine and reduces the endurance time of the construction machinery. Summary of the Invention

[0004] In view of this, the embodiments of the present application are dedicated to providing a control valve group, a hydraulic system, a front crane and an arm extension and retraction control method, which can cooperate with the first reversing valve and the second reversing valve to reduce the oil supply flow of the oil pump and reduce the pipeline pressure loss when the arm is extended without load, thereby saving working energy consumption.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present disclosure provides a control valve group for a reach stacker, comprising: a first reversing valve and a second reversing valve, wherein the first reversing valve and the second reversing valve cooperate to switch the boom of the reach stacker between a boom unloaded extended state, a boom loaded extended state, a boom loaded retracted state, and a boom unloaded retracted state; wherein:

[0007] The first reversing valve includes a first oil inlet, a first oil return port, a first working oil port, a second working oil port, and a third working oil port. The first working oil port is used to communicate with the rodless chamber of the boom telescopic oil cylinder of the reach crane through a first pipeline. The second working oil port is used to communicate with the rod chamber of the boom telescopic oil cylinder through a second pipeline. The first oil inlet is used to communicate with the hydraulic pump.

[0008] The second reversing valve includes a second oil inlet, a second oil return port, a fourth working oil port and a fifth working oil port, the fourth working oil port is connected to the rodless chamber via a third pipeline, and the second oil inlet is connected to the third working oil port via a fourth pipeline;

[0009] The first reversing valve has a first working position, in which the first oil inlet is connected to the first working oil port, and the second working oil port is connected to the third working oil port;

[0010] The second reversing valve has a first working position, in which the second oil inlet is connected to the fourth working oil port;

[0011] When the boom is in an unloaded extended state, the first reversing valve is in the first working position and the second reversing valve is in the first working position, and at the same time, the third working oil port of the first reversing valve is connected to the second oil inlet of the second reversing valve, so that the hydraulic oil in the rod chamber can flow through the first reversing valve and the second reversing valve and return to the third pipeline;

[0012] The boom no-load means that the load of the boom is less than a preset load value.

[0013] In a feasible implementation, the second reversing valve has a second working position, in which the second oil inlet and the second oil return port are connected;

[0014] When the boom is in a heavily loaded extended state, the first reversing valve is in the first working position and the second reversing valve is in the second working position; at the same time, the third working oil port of the first reversing valve is connected to the second oil inlet port of the second reversing valve, so that the hydraulic oil in the rod chamber can flow through the first reversing valve and the second reversing valve back to the oil tank assembly;

[0015] The boom overload means that the boom load is greater than a preset load value.

[0016] In a feasible implementation, the first reversing valve has a second working position, in which the first working oil port and the first oil return port are connected, and the second reversing valve has a third working position, in which the fifth working oil port and the second oil return port are connected;

[0017] When the boom is in the retracted state with a heavy load and a small elevation angle, the first reversing valve is in the second working position and the second reversing valve is in the third working position; so that the hydraulic oil in the rodless chamber can flow through the first working oil port through the first reversing valve and return to the oil tank assembly, and at the same time flow through the fifth working oil port through the second reversing valve and return to the oil tank assembly.

[0018] In a feasible implementation, the control valve group also includes a third reversing valve, and the third reversing valve includes a sixth working oil port and a third oil inlet. The sixth working oil port is used to communicate with the oil inlet chamber of the arm flip cylinder, and the third oil inlet is used to communicate with the hydraulic pump.

[0019] In a second aspect, a hydraulic system is provided, comprising:

[0020] Boom telescopic cylinder;

[0021] Boom tilt cylinder;

[0022] Fuel tank assembly;

[0023] A control valve assembly as described in any one of the above.

[0024] In a feasible implementation, the method further includes:

[0025] A pressure acquisition unit, used to acquire the pressure of the rodless chamber of the boom telescopic oil cylinder, the rod chamber of the boom telescopic oil cylinder, and the oil inlet chamber of the boom tilting oil cylinder;

[0026] An angle acquisition unit, used to acquire the tilt angle of the boom;

[0027] A boom extension position acquisition unit, configured to acquire the boom extension position;

[0028] a controller electrically connected to the pressure acquisition unit, the angle acquisition unit, and the load acquisition unit;

[0029] In which, the controller is able to obtain the pressure information of the rodless chamber of the boom telescopic cylinder, the rod chamber of the boom telescopic cylinder, and the oil inlet chamber of the boom flip cylinder, as well as the boom inclination angle information and the boom extension position information, and calculate the boom load based on the obtained pressure information of the oil inlet chamber of the boom flip cylinder, the boom inclination angle information and the boom extension position information, and judge the boom working status based on the obtained boom inclination angle information and the boom load information to control the first reversing valve and the second reversing valve to switch the working positions.

[0030] In a third aspect, a reach stacker is provided, comprising the hydraulic system as described above.

[0031] In a fourth aspect, a method for controlling the extension and retraction of a boom of a reach crane is provided, comprising:

[0032] The boom of the reach crane is controlled to be extended and retracted by the control valve group as described in any one of the above items, and the boom extension and retraction control method includes:

[0033] Obtaining the inclination angle and extension position of the boom, and obtaining the pressures of the rodless chamber of the boom telescopic cylinder, the rod chamber of the boom telescopic cylinder, and the oil inlet chamber of the boom tilting cylinder;

[0034] The boom load is calculated based on the pressure of the oil inlet chamber of the boom tilting cylinder, the boom tilt angle and the boom extension position;

[0035] The total resistance overcome by the boom telescopic cylinder during retraction is calculated based on the boom tilt angle and the boom load;

[0036] Determine the working status of the boom according to the boom load, the boom tilt angle and the total resistance overcome by the boom telescopic cylinder when it is retracted;

[0037] Controlling the working positions of the first reversing valve and the second reversing valve.

[0038] In a feasible implementation, judging the boom working state according to the boom tilt angle and the boom load to control the working positions of the first reversing valve and the second reversing valve includes:

[0039] When the boom is in the extended state, the boom load is less than a preset load value, the boom is judged to be in the no-load extended state, the first reversing valve is controlled to be in the first working position, and the second reversing valve is controlled to be in the first working position;

[0040] When the boom is in the extended state, the boom load is greater than a preset load value, the boom is judged to be in the heavy-load extended state, the first reversing valve is controlled to be in the first working position, and the second reversing valve is controlled to be in the second working position.

[0041] In a feasible implementation, judging the boom working state according to the boom tilt angle and the total resistance overcome by the boom telescopic cylinder when retracting to control the working positions of the first reversing valve and the second reversing valve includes:

[0042] When the boom is in the retracted state, the actual elevation angle of the boom is less than the preset elevation angle value of the boom, and the total resistance overcome by the boom telescopic cylinder in retracting is greater than the preset total retraction resistance value, the boom is judged to be in the heavy-load small elevation angle retracted state, and the first reversing valve is controlled to be in the second working position, and the second reversing valve is controlled to be in the third working position;

[0043] When the boom is in the retracted state, the actual elevation angle of the boom is greater than the preset elevation angle value of the boom, and the total resistance overcome by the retraction of the boom telescopic cylinder is less than the preset total retraction resistance value, the boom is judged to be in a heavy-loaded large elevation angle retraction state, and the first reversing valve is controlled to be in the third working position, and the second reversing valve is controlled to be in the fourth working position.

[0044] An embodiment of the present application provides a control valve group. When the boom is in an unloaded extended state, the hydraulic oil flowing back in the rod chamber of the boom telescopic cylinder can enter the second reversing valve through the third working oil port of the first reversing valve, and then enter the rodless chamber of the boom telescopic cylinder through the fourth working oil port of the second reversing valve, thereby reducing the amount of oil supplied by the hydraulic pump to the rodless chamber of the boom telescopic cylinder through the first reversing valve, thereby reducing the oil supply flow of the oil pump and reducing the pressure loss in the pipeline, thereby saving working energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Shown is a structural diagram of the hydraulic system.

[0046] Reference numerals:

[0047] 1. First reversing valve; 101. First oil inlet; 102. First oil return port; 103. First working oil port; 104. Second working oil port; 105. Third working oil port;

[0048] 2. Second reversing valve; 201. Second oil inlet; 202. Second oil return port; 203. Fourth working oil port; 204. Fifth working oil port;

[0049] 3. Third reversing valve; 301. Sixth working oil port; 302. Third oil inlet port; 303. Third oil return port;

[0050] 401, first pipeline; 402, second pipeline; 403, third pipeline; 404, fourth pipeline; 405, fifth pipeline; 406, sixth pipeline; 407, seventh pipeline;

[0051] 5. Boom telescopic cylinder;

[0052] 601, first boom tilting cylinder; 602, second boom tilting cylinder;

[0053] 7. Fuel tank assembly;

[0054] 801, first pressure sensor; 802, second pressure sensor; 803, third pressure sensor; 804, fourth pressure sensor;

[0055] 9. Angle sensor; 10. Displacement sensor; 11. Hydraulic pump; 12. Drive motor; 13. Safety valve; 14. Check valve. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0057] In the prior art, a hydraulic system is used to extend and retract the boom to move the loaded cargo. A conventional hydraulic system includes a boom extension cylinder 5, a boom tilt cylinder, a control valve assembly, a hydraulic pump 11, a drive motor 12, and a tank assembly 7. The drive motor 12 is used to drive the hydraulic pump 11, which pumps the hydraulic oil in the tank assembly 7 through a pipeline to the control valve assembly. The control valve assembly switches its operating position according to the boom's desired operating state, allowing the hydraulic oil to flow through the pipeline, through the control valve assembly, and into the boom extension cylinder 5 or the boom tilt cylinder. Similarly, the hydraulic oil in the boom extension cylinder 5 or the boom tilt cylinder can flow back to the tank assembly 7 through the control valve assembly.

[0058] When the boom is extended without load, the rodless cavity of the boom telescopic cylinder 5 is larger than the rod cavity, so the hydraulic pump 11 needs to pump a large amount of hydraulic oil into the rodless cavity. This results in high pump flow, high pressure loss in the system pipeline, and high energy consumption, which increases the energy consumption of the entire machine and reduces the endurance of the construction machine.

[0059] Regarding the above issues, refer to Figure 1 The present invention provides a control valve assembly for a reach stacker, comprising a first reversing valve 1 and a second reversing valve 2. The first reversing valve 1 and the second reversing valve 2 cooperate to switch the reach stacker's boom between an unloaded extended state, a loaded extended state, a loaded retracted state, and an unloaded retracted state. The first reversing valve 1 has a first oil inlet 101, a first oil return port 102, a first operating oil port 103, a second operating oil port 104, and a third operating oil port 105. The first oil inlet 101 is connected to the hydraulic pump 11 via the fifth pipeline 405, so that the hydraulic pump 11 pumps the hydraulic oil in the oil tank assembly 7 into the first reversing valve 1 through the first oil inlet 101. The first working oil port 103 is connected to one end of the first pipeline 401, the other end of which is connected to the rodless chamber of the boom telescopic cylinder 5. The first working oil port 103 can supply hydraulic oil to the rodless chamber via the first pipeline 401, or serve as a return channel for the rodless chamber. The second working oil port 104 is connected to one end of the second pipeline 402, the other end of which is connected to the rod chamber of the boom telescopic cylinder 5. The second working oil port 104 can supply hydraulic oil to the rod chamber via the second pipeline 402, or serve as a return channel for the rod chamber. The first oil inlet 101 is used to communicate with the hydraulic pump 11, and hydraulic oil is supplied to the first reversing valve 1 via the hydraulic pump 11.

[0060] The control valve assembly also includes a second reversing valve 2, which has a second oil inlet 201, a second oil return port 202, a fourth working oil port 203, and a fifth working oil port 204. The fourth working oil port 203 is connected to one end of a third pipeline 403, the other end of which can be directly connected to the rodless chamber. The fourth working oil port 203 can supply hydraulic oil to the rodless chamber through the third pipeline 403, or serve as a return channel for the rodless chamber. Of course, the other end of the third pipeline 403 can also be connected to the first pipeline 401, thereby reducing the number of connection points between the rodless chamber and the pipelines on the boom telescopic cylinder 5 and simplifying the overall structure. The second oil inlet 201 of the second reversing valve 2 is connected to the third working oil port 105 of the first reversing valve 1 via the fourth pipeline 404, allowing the hydraulic oil in the first reversing valve 1 to enter the third working oil port 105 through the fourth pipeline 404.

[0061] Among them, when the boom is in an unloaded extended state, the first reversing valve 1 has a first working position, and the second reversing valve 2 has a first working position. The first working position of the first reversing valve 1 is that the first oil inlet 101 and the first working oil port 103 are connected, so that the hydraulic oil in the oil tank assembly 7 flows through the first oil inlet 101, the first working oil port 103, and the first pipeline 401 in sequence to enter the rodless cavity of the boom telescopic cylinder 5; the second working oil port 104 and the third working oil port 105 are connected, so that the hydraulic oil in the rod cavity of the boom telescopic cylinder 5 flows through the second pipeline 402, the second working oil port 104, and the third working oil port 105 in sequence to realize reflux. The first working position of the second reversing valve 2 connects the second oil inlet 201 and the fourth working oil port 203. When the first reversing valve 1 is in the first working position, the third working oil port 105 of the first reversing valve 1 connects with the second oil inlet 201 of the second reversing valve 2, allowing the hydraulic oil in the rod chamber of the boom telescopic cylinder 5 to flow through the first reversing valve 1, then through the second reversing valve 2 and back into the third pipeline 403. In this way, the hydraulic oil discharged from the rod chamber of the boom telescopic cylinder 5 is reused, entering the second reversing valve 2 and merging with the hydraulic oil pumped into the first pipeline 401 by the hydraulic pump 11, thereby reducing the amount of hydraulic oil pumped into the first pipeline 401 by the hydraulic pump 11 and achieving energy savings.

[0062] The boom is considered unloaded when the boom's load is less than the preset load value. This means the boom is currently carrying less than its preset or designed target load value, indicating that the boom is not fully loaded and has additional capacity available for lifting heavier loads. For example, an unloaded boom refers to a boom with no load attached to its spreader. Alternatively, an unloaded boom refers to a boom with a load less than the preset load value attached to its spreader. In these cases, the boom is still considered unloaded.

[0063] In one feasible implementation, the second reversing valve 2 has a second working position, where the second oil inlet 201 and the second oil return port 202 are connected. When the boom is in a heavily loaded extended state, the first reversing valve 1 is in the first working position, and the second reversing valve 2 is in the second working position. The third working oil port 105 of the first reversing valve 1 is connected to the second oil inlet 201 of the second reversing valve 2, so that the hydraulic oil in the rod chamber can flow through the first reversing valve 1, through the second reversing valve 2, and back to the tank assembly 7. In this way, the second reversing valve 2 serves as a flow device for the hydraulic oil to flow back to the tank assembly 7, and the hydraulic pump 11 is used to supply hydraulic oil to the rodless chamber of the boom telescopic cylinder 5 separately. Compared with traditional hydraulic systems, the thrust of the boom telescopic cylinder 5 is maximized under the same driving pressure.

[0064] The boom overload mentioned above refers to the boom load exceeding the preset load value. That is, the weight currently carried by the boom exceeds its preset or designed target load value. For example, a boom overload refers to the boom spreader being fully loaded with a suspended object, in which case the boom is considered overloaded. Alternatively, a boom overload refers to the boom spreader being partially loaded with a suspended object, but the weight of the suspended object exceeds the preset load value, in which case the boom is still considered overloaded.

[0065] In a feasible implementation, the first reversing valve 1 has a second working position, in which the first working oil port 103 is connected to the first oil return port 102, and the second reversing valve 2 has a third working position, in which the fifth working oil port 204 is connected to the second oil return port 202, and the fifth working oil port 204 is connected to the rodless chamber of the boom telescopic cylinder 5 through the third pipeline 403. When the boom is in a heavy-load, small-angle retraction state, the first reversing valve 1 is in the second working position, and the second reversing valve 2 is in the third working position; so that the hydraulic oil in the rodless chamber of the boom telescopic cylinder 5 can flow through the first working oil port 103 through the first reversing valve 1 and return to the oil tank assembly 7, and flow through the second reversing valve 2 through the fifth working oil port 204 and return to the oil tank assembly 7. In this way, the hydraulic oil in the rodless chamber of the boom telescopic cylinder 5 returns through the first reversing valve 1 and the second reversing valve 2. Compared with the traditional hydraulic system, at the same boom retraction speed, the return oil valve core area is increased, the back pressure of the return oil pipeline is reduced, and the driving pressure of the rod chamber of the boom telescopic cylinder 5 is reduced, thereby achieving energy-saving effect.

[0066] In another feasible implementation, the first reversing valve 1 has a third working position, and the third working position of the first reversing valve 1 is that the first oil inlet 101 and the second working oil port 104 are connected, and the first working oil port 103 and the first oil return port 102 are connected. The second reversing valve 2 has a fourth working position. When the first reversing valve 1 is in the third working position and the second reversing valve 2 is in the fourth working position, the third working oil port 105 of the first reversing valve 1 and the second oil inlet 201 of the second reversing valve 2 are disconnected, and the second reversing valve 2 remains in the middle position. When the boom is retracted at a heavy load and a large elevation angle, the first reversing valve 1 is in the third working position and the second reversing valve 2 is in the fourth working position. This allows the hydraulic oil in the oil tank assembly 7 to be supplied to the rod chamber of the boom telescopic cylinder 5 sequentially through the first oil inlet 101, the second working oil port 104, and the second pipeline 402. Furthermore, the hydraulic oil in the rodless chamber of the boom telescopic cylinder 5 flows back to the oil tank assembly 7 sequentially through the first pipeline 401, the first working oil port 103, and the first oil return port 102. In this way, at the same cylinder speed, the oil return valve core area is reduced, the back pressure of the oil return pipeline is increased, and the supporting pressure of the rodless chamber of the boom telescopic cylinder 5 is used to offset the component force of the weight of the boom inner barrel, the spreader, and the hoisted object on the sliding axis of the boom inner barrel. This avoids the safety risk of stall retraction caused by insufficient supporting pressure in the rodless chamber of the boom telescopic cylinder 5, ensuring safe construction.

[0067] In one feasible implementation, the control valve group further includes a third reversing valve 3, which includes a sixth working oil port 301, a third oil inlet 302, and a third oil return port 303. The sixth working oil port 301 is used to communicate with the oil inlet chamber of the boom tilt cylinder. Specifically, the third oil inlet 302 is connected to the hydraulic pump 11 via a fifth pipeline 405. A plurality of third oil return ports 303 can be provided, which are connected to the oil tank assembly 7 via a sixth pipeline 406. The sixth working oil port 301 is connected to the boom tilt cylinder via a pipeline. In this way, when the boom tilt angle is increased, the third oil inlet 302 is connected to the sixth working oil port 301, the hydraulic pump 11 pumps hydraulic oil to the third oil inlet 302 through the pipeline, and causes the hydraulic oil to flow through the sixth working oil port 301 into the oil inlet chamber of the boom tilt cylinder, thereby extending the boom tilt cylinder and increasing the boom tilt angle. When reducing the arm tilt angle, the sixth working oil port 301 and the third oil return port 303 are connected, so that the hydraulic oil in the oil inlet chamber of the arm flip cylinder flows back to the sixth working oil port 301, and the hydraulic oil flows through the third oil return port 303 into the oil tank assembly 7, thereby retracting the arm flip cylinder and reducing the arm tilt angle.

[0068] In a second aspect, a hydraulic system is provided, comprising a boom telescopic cylinder 5 for driving a boom to change its extension length, and a boom tilt cylinder for driving a boom to change its tilt angle. A tank assembly 7 is used to store hydraulic oil. A hydraulic pump 11 pumps the hydraulic oil in the tank assembly 7 to a control valve group, where different reversing valves control the distribution of hydraulic oil to the boom telescopic cylinder 5 and the boom tilt cylinder. Different reversing valves also control the return of hydraulic oil from the boom telescopic cylinder 5 and the boom tilt cylinder to the tank assembly 7. Preferably, two hydraulic pumps 11 are provided, and the two hydraulic pumps 11 operate synchronously to pump hydraulic oil, thereby improving hydraulic oil pumping efficiency.

[0069] In addition, the control valve group also includes a safety valve 13. The hydraulic pump 11 is connected to the first oil inlet 101 of the first reversing valve 1 and the third oil inlet 302 of the third reversing valve 3 through a fifth pipeline 405. The oil tank assembly 7 is connected to the first oil return port 102 of the first reversing valve 1, the second oil return port 202 of the second reversing valve 2, and the third oil return port 303 of the third reversing valve 3 through a sixth pipeline 406. A seventh pipeline 407 is connected between the fifth pipeline 405 and the sixth pipeline 406, and the safety valve 13 is arranged on the seventh pipeline 407. In this way, the safety valve 13 serves as a protective device and automatically opens when the system pressure exceeds a predetermined value. That is, when the pressure in the fifth pipeline 405 exceeds a predetermined value when the hydraulic pump 11 is used to supply oil, the safety valve 13 can open and send the hydraulic oil in the fifth pipeline 405 to the sixth pipeline 406 through the seventh pipeline 407, and then use the sixth pipeline 406 to return the excess hydraulic oil to the oil tank assembly 7, thereby reducing the system pressure and preventing equipment damage and safety accidents.

[0070] Furthermore, the control valve assembly includes a one-way valve 14, which is disposed on the fifth pipeline 405 near the outlet of the hydraulic pump 11 to prevent hydraulic oil from flowing back through the fifth pipeline 405. When two hydraulic pumps 11 are provided, two corresponding one-way valves 14 are provided, so that each hydraulic pump 11 has a corresponding one-way valve 14.

[0071] In a feasible implementation, a pressure acquisition unit is further included to acquire the pressure of the rodless chamber, the rod chamber, and the oil inlet chamber of the boom telescopic cylinder 5. Specifically, two boom tilt cylinders are provided. Taking the first boom tilt cylinder 601 and the second boom tilt cylinder 602 as examples, the pressure acquisition unit includes a first pressure sensor 801, a second pressure sensor 802, a third pressure sensor 803, and a fourth pressure sensor 804. The first pressure sensor 801 is used to detect the support pressure of the first boom tilt cylinder 601 and is displayed as P1. The second pressure sensor 802 is used to detect the support pressure of the second boom tilt cylinder 602 and is displayed as P2. The third pressure sensor 803 is used to detect the pressure of the rodless chamber of the boom telescopic cylinder 5 and is displayed as P3. The fourth pressure sensor 804 is used to detect the pressure of the rod chamber of the boom telescopic cylinder 5 and is displayed as P4.

[0072] The angle acquisition unit is used to obtain the tilt angle of the boom. The angle acquisition unit is an angle sensor 9. The angle sensor 9 is used to feed back the actual elevation angle α of the boom. When the engineering machine is a front loader, preferably 0°≤α≤60°.

[0073] The boom extension position acquisition unit is used to obtain the boom extension position and includes a displacement sensor 10. The displacement sensor 10 is used to obtain the boom extension position L. Thus, the controller calculates the weight G of the hoisted object based on the boom extension position L, the actual boom elevation angle α, the support pressure P1 of the first boom tilt cylinder 601, and the support pressure P2 of the second boom tilt cylinder 602.

[0074] In addition, the controller can determine the working status of the boom according to the acquired boom tilt angle information and boom load information to control the first reversing valve and the second reversing valve to switch the working positions.

[0075] In a third aspect, a reach stacker is provided, comprising the hydraulic system as described above.

[0076] In a fourth aspect, a boom extension and retraction control method for a reach crane is provided. The boom of the reach crane is controlled to be extended and retracted by the control valve group as described above. The boom extension and retraction control method includes:

[0077] Obtain the tilt angle and extension position of the boom, and obtain the pressures of the rodless chamber of the boom telescopic cylinder 5, the rod chamber of the boom telescopic cylinder 5, and the oil inlet chamber of the boom tilting cylinder;

[0078] The boom load is calculated based on the pressure of the oil inlet chamber of the boom tilting cylinder, the boom tilt angle and the boom extension position;

[0079] The total resistance F to be overcome by the telescopic cylinder 5 of the boom is calculated based on the boom tilt angle and the boom load;

[0080] The working status of the boom is determined based on the boom load, the boom tilt angle and the total resistance F that the boom telescopic cylinder 5 overcomes when retracting.

[0081] Control the working positions of the first reversing valve 1 and the second reversing valve 2.

[0082] In one embodiment, the total resistance F to be overcome by the boom telescopic cylinder 5 when retracting is calculated based on the boom tilt angle and the boom load. The specific calculation formula is:

[0083] When the boom is retracted, the total resistance F overcome by the boom telescopic cylinder 5 is reduced to:

[0084] F shrink=F1-Fm+Fp3=(M0+G)*(sinα-μ*cosα)+P3*A1

[0085] When α0=α

[0086] (sinα-μ*cosα)=0

[0087] Among them, F1 is the component force of the boom inner cylinder, the weight of the sling and the hoisted object on the sliding axis of the boom inner cylinder, Fm is the friction force of the boom inner cylinder, the weight of the sling and the hoisted object on the sliding axis of the boom inner cylinder, Fp3 is the resistance generated by the hydraulic back pressure when the boom telescopic cylinder 5 is retracted, and Fp4 is the resistance generated by the hydraulic back pressure when the boom telescopic cylinder 5 is extended;

[0088] M0 is the weight of the boom inner tube and the sling, G is the weight of the hoisted object (i.e. the boom load), P3 is the pressure in the rodless cavity, P4 is the pressure in the rod cavity, α is the actual elevation angle of the boom, α0 is the preset elevation angle value of the boom, μ is the sliding friction coefficient of the boom inner tube, A1 is the effective area of ​​the rodless cavity, and A2 is the effective area of ​​the rod cavity.

[0089] Of course, other calculation methods can also be used to obtain the boom load and the total resistance F to be overcome by the boom telescopic cylinder 5. For example, a weight detection device can be installed on the spreader to directly obtain the weight G of the hoisted object.

[0090] It can be understood that when the boom is extending, the pressure P3 in the rodless cavity of the boom telescopic cylinder 5 always outputs positive pressure to overcome gravity, friction and P4*A2 cylinder resistance. These three forces are resistance and the force direction will not change due to the tilt angle of the boom and no load or heavy load. Therefore, the total resistance F overcome when the boom is extended is not judged.

[0091] The following describes various embodiments of this solution in detail in combination with the above embodiments.

[0092] In the first embodiment, when the boom is extended, the boom load (hoisting object weight G) is less than the preset load value, and the boom is judged to be in an unloaded extended state, and the first reversing valve 1 is controlled to be in the first working position, and the second reversing valve 2 is controlled to be in the first working position.

[0093] Specifically, the first oil inlet 101 in the first reversing valve 1 is connected to the hydraulic pump 11 through the fifth pipeline 405, so that the hydraulic pump 11 pumps the hydraulic oil in the oil tank assembly 7 into the first reversing valve 1 through the fifth pipeline 405 and the first oil inlet 101. The hydraulic oil in the first reversing valve 1 enters the first pipeline 401 through the first working oil port 103, and enters the rodless chamber of the arm telescopic cylinder 5 from the first pipeline 401. At the same time, the second working oil port 104 and the third working oil port 105 of the first reversing valve 1 are connected. The third working oil port 105 of the first reversing valve 1 is connected to the second oil inlet 201 of the second reversing valve 2 via the fourth pipeline 404. The hydraulic oil in the rod chamber of the boom extension cylinder 5 enters the first reversing valve 1 through the second working oil port 104 via the second pipeline 402. It then enters the second reversing valve 2 through the third working oil port 105, the fourth pipeline 404, and the second oil inlet 201. It then merges with the hydraulic oil in the first pipeline 401 through the fourth working oil port 203 and the third pipeline 403, and is then fed into the rodless chamber of the boom extension cylinder 5. This allows for rapid boom extension, reduces the oil flow of the hydraulic pump 11, minimizes pipeline pressure loss, and reduces energy consumption.

[0094] In the second embodiment, when the boom is extended, the boom load (hoisting object weight G) is greater than the preset load value, and the boom is judged to be in a heavy-load extended state, and the first reversing valve 1 is controlled to be in the first working position, and the second reversing valve 2 is controlled to be in the second working position.

[0095] Specifically, the first oil inlet 101 in the first reversing valve 1 is connected to the hydraulic pump 11 through the fifth pipeline 405, so that the hydraulic pump 11 pumps the hydraulic oil in the oil tank assembly 7 into the first reversing valve 1 through the fifth pipeline 405 and the first oil inlet 101. The hydraulic oil in the first reversing valve 1 enters the first pipeline 401 through the first working oil port 103, and enters the rodless chamber of the arm telescopic cylinder 5 from the first pipeline 401. At the same time, the second oil inlet 201 of the second reversing valve 2 is connected to the second oil return port 202, which is then connected to the tank assembly 7 via the sixth pipeline 406. The second working oil port 104 of the first reversing valve 1 is connected to the third working oil port 105, which is then connected to the second oil inlet 201 of the second reversing valve 2 via the fourth pipeline 404. The hydraulic oil in the rod chamber of the boom telescopic cylinder 5 enters the first reversing valve 1 through the second working oil port 104 via the second pipeline 402, then enters the second reversing valve 2 via the third working oil port 105, the fourth pipeline 404, and the second oil inlet 201. Finally, it enters the tank assembly 7 via the second oil return port 202 and the sixth pipeline 406. In this way, the hydraulic pump 11 supplies hydraulic oil solely to the rodless chamber of the boom telescopic cylinder 5, maximizing the thrust of the boom telescopic cylinder 5 and meeting the requirements for heavy-load extension.

[0096] In the third embodiment, when the boom is in the retracted state, the actual elevation angle of the boom α is less than α0, and the boom retraction resistance F retracts > 0, it is determined that the boom is in a heavy-loaded small elevation angle retracted state, and the first reversing valve 1 is controlled to be in the second working position, and the second reversing valve 2 is controlled to be in the third working position.

[0097] Specifically, the first oil inlet 101 in the first reversing valve 1 is connected to the hydraulic pump 11 through the fifth pipeline 405, so that the hydraulic pump 11 pumps the hydraulic oil in the oil tank assembly 7 into the first reversing valve 1 through the fifth pipeline 405 and the first oil inlet 101, and the hydraulic oil in the first reversing valve 1 enters the rod chamber of the arm telescopic cylinder 5 through the second working oil port 104 and the second pipeline 402. At the same time, the first working oil port 103 of the first reversing valve 1 is connected to the first oil return port 102, and the fifth working oil port 204 of the second reversing valve 2 is connected to the second oil return port 202. The hydraulic oil discharged from the rodless chamber of the boom telescopic cylinder 5 enters the first pipeline 401 and is split. Some of the hydraulic oil flows back to the tank assembly 7 along the first pipeline 401 through the first working oil port 103 and the first oil return port 102, while the other part of the hydraulic oil flows back to the tank assembly 7 along the third pipeline 403 through the fifth working oil port 204, the second oil return port 202, and the sixth pipeline 406. In this way, the hydraulic oil in the rodless chamber of the boom telescopic cylinder 5 is returned through the first reversing valve 1 and the second reversing valve 2, increasing the area of ​​the oil return valve core, reducing the back pressure of the oil return pipeline, and reducing the driving pressure of the rod chamber of the boom telescopic cylinder 5, thereby achieving an energy-saving effect.

[0098] In the fourth embodiment, when the boom is in the retracted state, the actual elevation angle α of the boom is greater than α0, and the boom retraction resistance F is less than 0, it is determined that the boom is in a heavy-loaded, large-elevation-angle retracted state, and the first reversing valve 1 is controlled to be in the third working position, and the second reversing valve 2 is controlled to be in the fourth working position.

[0099] Specifically, the first oil inlet 101 in the first reversing valve 1 is connected to the hydraulic pump 11 via the fifth pipeline 405, allowing the hydraulic pump 11 to pump the hydraulic oil in the oil tank assembly 7 into the first reversing valve 1 through the fifth pipeline 405 and the first oil inlet 101. The hydraulic oil in the first reversing valve 1 then enters the rod chamber of the boom telescopic cylinder 5 through the second working oil port 104 and the second pipeline 402. At the same time, the first working oil port 103 of the first reversing valve 1 is connected to the first oil return port 102, and the third working oil port 105 is inoperative, disconnected from the second reversing valve 2. The hydraulic oil discharged from the rodless chamber of the boom telescopic cylinder 5 enters the first pipeline 401 and enters the first reversing valve 1 through the first working oil port 103, and then flows back to the oil tank assembly 7 through the first oil return port 102. In this way, the single valve core oil return mode of the first reversing valve 1 is adopted to reduce the area of ​​the return oil valve core, increase the back pressure of the return oil pipeline, and use the support pressure of the rodless chamber of the boom telescopic cylinder 5 to offset the component force of the boom inner tube, sling and container weight on the sliding axis of the boom inner tube, avoiding the safety risk of stall retraction caused by insufficient support pressure of the rodless chamber of the boom telescopic cylinder 5, and ensuring safe construction.

[0100] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A control valve group for a reach stacker, characterized in that: include: The first reversing valve and the second reversing valve cooperate to switch the boom of the reach crane between the boom no-load extended state, the boom heavy-load extended state, the boom heavy-load retracted state, and the boom no-load retracted state; wherein, The first reversing valve includes a first oil inlet, a first oil return port, a first working oil port, a second working oil port, and a third working oil port. The first working oil port is used to communicate with the rodless chamber of the boom telescopic oil cylinder of the reach crane through a first pipeline. The second working oil port is used to communicate with the rod chamber of the boom telescopic oil cylinder through a second pipeline. The first oil inlet is used to communicate with the hydraulic pump. The second reversing valve includes a second oil inlet, a second oil return port, a fourth working oil port and a fifth working oil port, the fourth working oil port is connected to the rodless chamber via a third pipeline, and the second oil inlet is connected to the third working oil port via a fourth pipeline; The first reversing valve has a first working position, in which the first oil inlet is connected to the first working oil port, and the second working oil port is connected to the third working oil port; The second reversing valve has a first working position, in which the second oil inlet is connected to the fourth working oil port; When the boom is in an unloaded extended state, the first reversing valve is in the first working position and the second reversing valve is in the first working position, and at the same time, the third working oil port of the first reversing valve is connected to the second oil inlet of the second reversing valve, so that the hydraulic oil in the rod chamber can flow through the first reversing valve and the second reversing valve and return to the third pipeline; The boom no-load means that the load of the boom is less than a preset load value.

2. The control valve group according to claim 1, characterized in that: The second reversing valve has a second working position, in which the second oil inlet and the second oil return port are connected; When the boom is in a heavily loaded extended state, the first reversing valve is in the first working position and the second reversing valve is in the second working position; at the same time, the third working oil port of the first reversing valve is connected to the second oil inlet port of the second reversing valve, so that the hydraulic oil in the rod chamber can flow through the first reversing valve and the second reversing valve back to the oil tank assembly; The boom overload means that the boom load is greater than a preset load value.

3. The control valve assembly according to claim 1, characterized in that: The first reversing valve has a second working position, in which the first working oil port is connected to the first oil return port, and the second reversing valve has a third working position, in which the fifth working oil port is connected to the second oil return port; When the boom is in the retracted state with a heavy load and a small elevation angle, the first reversing valve is in the second working position and the second reversing valve is in the third working position; so that the hydraulic oil in the rodless chamber can flow through the first working oil port through the first reversing valve and return to the oil tank assembly, and at the same time flow through the fifth working oil port through the second reversing valve and return to the oil tank assembly.

4. The control valve assembly according to claim 1, characterized in that: The control valve group also includes a third reversing valve, which includes a sixth working oil port and a third oil inlet. The sixth working oil port is used to communicate with the oil inlet chamber of the arm tilting cylinder, and the third oil inlet is used to communicate with the hydraulic pump.

5. A hydraulic system, characterized in that: include: Boom telescopic cylinder; Boom tilt cylinder; Fuel tank assembly; The control valve assembly according to any one of claims 1 to 4.

6. The hydraulic system according to claim 5, characterized in that Also includes: A pressure acquisition unit, used to acquire the pressure of the rodless chamber of the boom telescopic oil cylinder, the rod chamber of the boom telescopic oil cylinder, and the oil inlet chamber of the boom tilting oil cylinder; An angle acquisition unit, used to acquire the tilt angle of the boom; A boom extension position acquisition unit, configured to acquire the boom extension position; a controller electrically connected to the pressure acquisition unit, the angle acquisition unit, and the arm extension position acquisition unit; In which, the controller is able to obtain the pressure information of the rodless chamber of the boom telescopic cylinder, the rod chamber of the boom telescopic cylinder, and the oil inlet chamber of the boom flip cylinder, as well as the boom inclination angle information and the boom extension position information, and calculate the boom load based on the obtained pressure information of the oil inlet chamber of the boom flip cylinder, the boom inclination angle information and the boom extension position information, and judge the boom working status based on the obtained boom inclination angle information and the boom load information to control the first reversing valve and the second reversing valve to switch the working positions.

7. A reach stacker, characterized in that: Comprising the hydraulic system of claim 6.

8. A method for controlling the extension and retraction of a front crane boom, characterized in that: The boom of a reach crane is telescopically controlled by a control valve assembly according to any one of claims 1 to 4, and the boom telescopic control method comprises: Obtaining the inclination angle and extension position of the boom, and obtaining the pressures of the rodless chamber of the boom telescopic cylinder, the rod chamber of the boom telescopic cylinder, and the oil inlet chamber of the boom tilting cylinder; The boom load is calculated based on the pressure of the oil inlet chamber of the boom tilting cylinder, the boom tilt angle and the boom extension position; The total resistance overcome by the boom telescopic cylinder during retraction is calculated based on the boom tilt angle and the boom load; Determine the working status of the boom according to the boom load, the boom tilt angle and the total resistance overcome by the boom telescopic cylinder when it is retracted; Controlling the working positions of the first reversing valve and the second reversing valve.

9. The boom extension and retraction control method according to claim 8, characterized in that: Determining the boom working state according to the boom tilt angle and the boom load to control the working positions of the first reversing valve and the second reversing valve includes: When the boom is in the extended state, the boom load is less than a preset load value, the boom is judged to be in the no-load extended state, the first reversing valve is controlled to be in the first working position, and the second reversing valve is controlled to be in the first working position; When the boom is in the extended state, the boom load is greater than a preset load value, the boom is judged to be in the heavy-load extended state, the first reversing valve is controlled to be in the first working position, and the second reversing valve is controlled to be in the second working position.

10. The boom extension and retraction control method according to claim 8, characterized in that: Determining the boom working state according to the boom tilt angle and the total resistance overcome by the boom telescopic cylinder when it is retracted, so as to control the working positions of the first reversing valve and the second reversing valve includes: When the boom is in the retracted state, the actual elevation angle of the boom is less than the preset elevation angle value of the boom, and the total resistance overcome by the boom telescopic cylinder in retracting is greater than the preset total retraction resistance value, the boom is judged to be in the heavy-load small elevation angle retracted state, and the first reversing valve is controlled to be in the second working position, and the second reversing valve is controlled to be in the third working position; When the boom is in the retracted state, the actual elevation angle of the boom is greater than the preset elevation angle value of the boom, and the total resistance overcome by the retraction of the boom telescopic cylinder is less than the preset total retraction resistance value, the boom is judged to be in a heavy-loaded large elevation angle retraction state, and the first reversing valve is controlled to be in the third working position, and the second reversing valve is controlled to be in the fourth working position.

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