Control valve group, hydraulic system, reach stacker and boom telescopic control method

Abstract

The invention relates to the technical field of hydraulic control, in particular to a control valve group, a hydraulic system, a reach stacker and a boom telescopic control method. Wherein the control valve group comprises a first reversing valve and a second reversing valve, and the first reversing valve and the second reversing valve are matched to enable the boom of the reach stacker to be switched in different states. When the boom is in a load extending state, the first reversing valve is located at a first working position, the second reversing valve is located at the first working position, and meanwhile, a third working oil port of the first reversing valve is communicated with a second oil inlet of the second reversing valve; and hydraulic oil in the rod cavity can flow through the second reversing valve to flow back to the third pipeline through the first reversing valve. Through cooperation of the first reversing valve and the second reversing valve, hydraulic oil in the rod cavity can flow through the second reversing valve to flow back to the third pipeline through the first reversing valve, when the boom stretches out in a loaded mode, the oil supply flow of the oil pump is reduced, pipeline pressure loss is reduced, and working energy consumption is reduced.

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] Crane is a commonly used construction machinery. The folding arm of the crane realizes the arm movement function by controlling the hydraulic cylinder through the hydraulic control system.

[0003] In the prior art, a reversing valve group is used to realize the extension and retraction of the boom telescopic cylinder, thereby realizing 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 whole 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 reduce the oil supply flow of the oil pump and reduce the pipeline pressure loss when the arm is extended without load through the cooperation of the first reversing valve and the second reversing valve, 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 crane, comprising: a first reversing valve and a second reversing valve, wherein the first reversing valve and the second reversing valve cooperate to enable the boom of the reach crane to switch between a boom unloaded extended state, a boom heavily loaded extended state, a boom heavily loaded retracted state, and a boom unloaded retracted state; wherein:

[0007] The first reversing valve comprises 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, and the first oil inlet is used to communicate with the hydraulic pump;

[0008] The second reversing valve comprises 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] Wherein, 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 a first working position and the second reversing valve is in a 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 flow back to the third pipeline;

[0012] The boom being unloaded 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 heavy-load 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 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 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 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;

[0017] When the boom is in a heavy-load, small-angle retracted state, 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 port. The sixth working oil port is used to communicate with the oil inlet chamber of the arm flip cylinder, and the third oil inlet port is used to communicate with the hydraulic pump.

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

[0020] Boom extension cylinder;

[0021] Boom tilting cylinder;

[0022] Fuel tank assembly;

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

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

[0025] A pressure acquisition unit, used to acquire the pressure 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;

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

[0027] A boom extension position acquisition unit, used for acquiring the boom extension position;

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

[0029] Among them, 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 state 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 boom extension and retraction control method for a front crane is provided, comprising:

[0032] The boom of the front crane is telescopically controlled by the control valve group as described in any one of the above, and the boom telescopic control method includes:

[0033] Obtain the inclination angle of the boom and the extension position of the boom, and obtain the pressure 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 telescopic cylinder of the boom is calculated according to the inclination angle of the boom and the load of the boom;

[0036] The working state of the boom is determined 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 located at the first working position, and the second reversing valve is controlled to be located at 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 working state of the boom according to the tilt angle of the boom 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:

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

[0043] When the boom is in the retracted state, when 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 retracting boom telescopic cylinder is less than the preset total retraction resistance value, the boom is judged to be in a heavy-loaded and large-angle retracted 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] A control valve group is provided in an embodiment of the present application. When the boom is in an unloaded and extended state, the hydraulic oil refluxed 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 of the pipeline, thereby saving working energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Shown is a schematic 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. The third reversing valve; 301. The sixth working oil port; 302. The third oil inlet port; 303. The 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, a first pressure sensor; 802, a second pressure sensor; 803, a third pressure sensor; 804, a 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 the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0057] In the prior art, a hydraulic system is used to realize the extension and retraction of the boom to drive the movement of the loaded cargo. The conventional hydraulic system includes a boom extension cylinder 5, a boom tilt cylinder, a control valve group, a hydraulic pump 11, a drive motor 12, and a tank assembly 7, wherein the drive motor 12 is used to drive the hydraulic pump 11 to work, and the hydraulic pump 11 pumps the hydraulic oil in the tank assembly 7 to the control valve group through a pipeline. The control valve group switches the working position according to the required working state of the boom, so that the hydraulic oil flows through the control valve group through the pipeline 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 group.

[0058] When the boom is extended without load, the hydraulic pump 11 needs to pump a large amount of hydraulic oil into the rodless cavity because the rodless cavity area of ​​the boom telescopic oil cylinder 5 is larger than the rod cavity area. In this way, there are problems such as large pump flow, high system pipeline pressure loss, and high energy consumption, which increases the energy consumption of the whole machine and reduces the endurance time of the construction machinery.

[0059] For the above problems, refer to Figure 1 The embodiment of the present application provides a control valve group for a reach crane, including 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 boom of the reach crane between an unloaded boom extension state, a heavily loaded boom extension state, a heavily loaded boom retracted state, and an unloaded boom retracted state. The first reversing valve 1 has a first oil inlet 101, a first oil return port 102, a first working oil port 103, a second working oil port 104, and a third working oil port 105. Among them, the first oil inlet 101 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 first oil inlet 101, and the first working oil port 103 is connected to one end of the first pipeline 401, and the other end of the first pipeline 401 is connected to the rodless chamber of the boom telescopic oil cylinder 5. The first working oil port 103 can supply hydraulic oil to the rodless chamber through the first pipeline 401, or be used as a reflux channel of the rodless chamber. The second working oil port 104 is connected to one end of the second pipeline 402, and the other end of the second pipeline 402 is connected to the rod chamber of the boom telescopic oil cylinder 5. The second working oil port 104 can supply hydraulic oil to the rod chamber through the second pipeline 402, or be used as a reflux channel of the rod chamber. The first oil inlet 101 is used to communicate with the hydraulic pump 11, and supply hydraulic oil to the first reversing valve 1 through the hydraulic pump 11.

[0060] The control valve group 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. Among them, the fourth working oil port 203 is connected to one end of the third pipeline 403, and the other end of the third pipeline 403 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 be used 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, which reduces the number of connection points between the rodless chamber and the pipeline on the boom telescopic cylinder 5, making the overall structure simpler. 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 through the fourth pipeline 404, and the hydraulic oil in the first reversing valve 1 can 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 achieve reflux. The first working position of the second reversing valve 2 is that the second oil inlet 201 is connected to 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 is connected to the second oil inlet 201 of the second reversing valve 2, so that the hydraulic oil in the rod chamber of the boom telescopic oil cylinder 5 can flow through the first reversing valve 1 and the second reversing valve 2 back to the third pipeline 403. In this way, the hydraulic oil discharged from the rod chamber of the boom telescopic oil cylinder 5 is reused, enters the second reversing valve 2 and merges with the hydraulic oil pumped into the first pipeline 401 by the hydraulic pump 11, reduces the amount of hydraulic oil pumped into the first pipeline 401 by the hydraulic pump 11, and achieves the effect of saving energy consumption.

[0062] The above-mentioned boom no-load means that the load of the boom is less than the preset load value. That is, the weight currently carried by the boom is less than its preset or designed target load value, which indicates that the boom is not working at full load and there is additional load capacity that can be used to lift heavier goods. For example, the boom no-load means that the boom hoist is not hanging a hoisting object. Or, the boom no-load means that the boom hoist is hanging a hoisting object that is less than the preset load value, and the boom is still judged to be in a no-load state.

[0063] In a feasible implementation, the second reversing valve 2 has a second working position, and the second working position of the second reversing valve 2 is that the second oil inlet 201 and the second oil return port 202 are connected; when the boom is in a heavy-load 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 return to the oil tank assembly 7. In this way, the second reversing valve 2 is used as a flow-through device for the hydraulic oil to return to the oil tank assembly 7, and the hydraulic pump 11 is used to supply hydraulic oil to the rodless chamber of the boom telescopic oil cylinder 5 alone. Compared with the traditional hydraulic system, under the same driving pressure, the thrust of the boom telescopic oil cylinder 5 is maximized.

[0064] The above-mentioned boom overload means that the load of the boom is greater than the preset load value. That is, the weight currently carried by the boom is greater than its preset or designed target load value. For example, the boom overload means that the boom hanger is fully loaded with the hoisting object, and the boom is judged to be in a overloaded state. Alternatively, the boom overload means that the boom hanger is not fully loaded with the hoisting object, but the weight of the hoisting object is greater than the preset load value, and the boom is still judged to be in a overloaded state.

[0065] In a feasible implementation, the first reversing valve 1 has a second working position, the second working position of the first reversing valve 1 is that the first working oil port 103 is connected to the first oil return port 102, the second reversing valve 2 has a third working position, the third working position is that 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. In the boom heavy-load small elevation 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 reversing valve 1 through the first working oil port 103 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, and 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. In the state of retracting the boom with heavy load and 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, so that the hydraulic oil in the oil tank assembly 7 is supplied to the rod chamber of the boom telescopic oil cylinder 5 through the first oil inlet 101, the second working oil port 104, and the second pipeline 402 in sequence, and the hydraulic oil in the rodless chamber of the boom telescopic oil cylinder 5 is returned to the oil tank assembly 7 through the first pipeline 401, the first working oil port 103, and the first oil return port 102 in sequence. 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 support pressure of the rodless chamber of the boom telescopic oil cylinder 5 is used to offset the component force of the weight of the boom inner cylinder, the hoisting device and the hoisting object on the sliding axis of the boom inner cylinder, so as to avoid the safety risk of stall retraction caused by insufficient support pressure of the rodless chamber of the boom telescopic oil cylinder 5, and ensure safe construction.

[0067] In a feasible implementation, the control valve group also includes a third reversing valve 3, and the third reversing valve 3 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 tilting cylinder. Specifically, the third oil inlet 302 is connected to the hydraulic pump 11 through the fifth pipeline 405, and the third oil return port 303 can be provided with multiple, and is connected to the oil tank assembly 7 through the sixth pipeline 406. The sixth working oil port 301 is connected to the boom tilting cylinder through the pipeline. In this way, when the tilt angle of the boom is increased, the third oil inlet 302 is connected to the sixth working oil port 301, and the hydraulic pump 11 pumps the hydraulic oil to the third oil inlet 302 through the pipeline, and allows the hydraulic oil to flow through the sixth working oil port 301 into the oil inlet chamber of the boom tilting cylinder, so that the boom tilting cylinder is extended and the tilt angle of the boom is increased. When reducing the tilt angle of the boom, 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 boom 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 boom flip cylinder and reducing the tilt angle of the boom.

[0068] In the second aspect, a hydraulic system is provided, including a boom telescopic oil cylinder 5 for driving the boom to change the extension length, and a boom tilting oil cylinder for driving the boom to change the tilt angle, a tank assembly 7 for storing hydraulic oil, a hydraulic pump 11 pumps the hydraulic oil in the tank assembly 7 to a control valve group, and different reversing valves control the distribution of hydraulic oil to the boom telescopic oil cylinder 5 and the boom tilting oil cylinder, and different reversing valves control the hydraulic oil of the boom telescopic oil cylinder 5 and the boom tilting oil cylinder to flow back to the tank assembly 7. Preferably, two hydraulic pumps 11 are provided, and the two hydraulic pumps 11 work synchronously to pump hydraulic oil to improve the 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 protection 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 tank assembly 7, thereby reducing the system pressure and preventing equipment damage and safety accidents.

[0070] Furthermore, the control valve group also includes a one-way valve 14, which is arranged on the fifth pipeline 405 and close to the outlet end of the hydraulic pump 11 to ensure that the hydraulic oil cannot flow back on 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 one-way valve 14 for use.

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

[0072] The angle acquisition unit is used to acquire the inclination 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 machinery is a front crane, preferably 0°≤α≤60°.

[0073] The boom extension position acquisition unit is used to acquire the boom extension position, and the boom extension position acquisition unit includes a displacement sensor 10, and the displacement sensor 10 is used to acquire the boom extension position L. In this way, the controller calculates the weight G of the hoisted object through the boom extension position L, the actual boom elevation angle α, the support pressure P1 of the first boom tilting cylinder 601, and the support pressure P2 of the second boom tilting cylinder 602.

[0074] Furthermore, the controller can determine the working state of the boom according to the acquired boom tilt angle information and boom load information, so as 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 control method for a reach crane is provided. The boom of the reach crane is extended and retracted by the control valve group as described above. The boom extension and retraction control method comprises:

[0077] Obtain the tilt angle of the boom and the extended position of the boom, and obtain the pressure 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 Fcontract overcome by the telescopic cylinder 5 of the boom is calculated based on the inclination angle of the boom and the load of the boom;

[0080] The working state of the boom is determined according to the boom load, the boom tilt angle and the total resistance F overcame by the boom telescopic cylinder 5 when it is retracted;

[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 that the telescopic cylinder 5 of the boom overcomes when retracting is calculated based on the inclination angle of the boom and the load of the boom, and 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 arm inner cylinder, the sling and the weight of the hoisted object on the sliding axis of the arm inner cylinder, Fm is the friction force of the arm inner cylinder, the sling and the weight of the hoisted object on the sliding axis of the arm inner cylinder, Fp3 is the resistance generated by the hydraulic back pressure of the arm telescopic cylinder 5 when it is retracted, and Fp4 is the resistance generated by the hydraulic back pressure of the arm telescopic cylinder 5 when it is extended;

[0088] M0 is the weight of the inner cylinder of the boom 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 inner cylinder of the boom, 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 Fcontract overcome by the boom telescopic cylinder 5. For example, a weight detection device can be installed on the sling 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 chamber of the boom telescopic cylinder 5 continuously outputs positive pressure to overcome gravity, friction and P4*A2 cylinder resistance. These three forces are resistances and the force direction will not change due to the tilt angle of the boom and whether it is empty or loaded. Therefore, the total resistance F overcome when the boom is extended is not judged.

[0091] The following describes various embodiments of the present invention 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 a preset load value, the boom is judged to be in an unloaded extended state, 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, and 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, and 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 through the fourth pipeline 404. The hydraulic oil in the rod chamber of the boom telescopic oil cylinder 5 enters the first reversing valve 1 through the second pipeline 402 from the second working oil port 104, and enters the second reversing valve 2 through the third working oil port 105, the fourth pipeline 404, and the second oil inlet 201, and 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 sent to the rodless chamber of the boom telescopic oil cylinder 5. In this way, the boom is quickly extended, the oil supply flow of the hydraulic pump 11 is reduced, the pipeline pressure loss is reduced, and the energy consumption is reduced.

[0094] In the second embodiment, when the boom is extended, the boom load (hoisting object weight G) is greater than a preset load value, the boom is judged to be in a heavy-load extended state, 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, and 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 and the second oil return port 202 of the second reversing valve 2 are connected, and the second oil return port 202 is connected to the oil tank assembly 7 through the sixth pipeline 406. The second working oil port 104 and the third working oil port 105 of the first reversing valve 1 are connected, and 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 through the fourth pipeline 404. The hydraulic oil in the rod chamber of the boom telescopic oil cylinder 5 enters the first reversing valve 1 from the second working oil port 104 through the second pipeline 402, and enters the second reversing valve 2 through the third working oil port 105, the fourth pipeline 404, and the second oil inlet 201, and then enters the oil tank assembly 7 through the second oil return port 202 and the sixth pipeline 406. In this way, the hydraulic pump 11 is used to supply hydraulic oil to the rodless chamber of the boom telescopic oil cylinder 5 alone, so that the thrust of the boom telescopic oil cylinder 5 is maximized, meeting the use requirements of heavy-load extension.

[0096] In the third embodiment, when the boom is in a 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 oil cylinder 5 enters the first pipeline 401 and is divided. A part of the hydraulic oil flows back to the oil tank assembly 7 along the first pipeline 401 through the first working oil port 103 and the first oil return port 102, and the other part of the hydraulic oil flows back to the oil 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 oil cylinder 5 returns oil 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 oil cylinder 5, achieving energy saving effect.

[0098] In the fourth embodiment, when the boom is in a retracted state, the actual elevation angle α of the boom is greater than α0, and the boom retraction resistance F retracts less than 0, it is determined that the boom is in a heavy-loaded, large-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 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 boom telescopic oil 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 does not work and is disconnected from the second reversing valve 2. The hydraulic oil discharged from the rodless chamber of the boom telescopic oil 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 oil return valve core, increase the back pressure of the oil return pipeline, and use the support pressure of the rodless chamber of the boom telescopic cylinder 5 to offset the component of the weight of the boom inner tube, sling and container on the sliding axis of the boom inner tube, thereby avoiding the safety risk of stall retraction caused by insufficient support pressure of the rodless chamber of the boom telescopic cylinder 5, thereby 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 substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A control valve group for a front loaders, characterized in that: include: The first reversing valve and the second reversing valve cooperate to enable the boom of the front crane to switch between an unloaded boom extended state, a heavily loaded boom extended state, a heavily loaded boom retracted state, and an unloaded boom retracted state; wherein, The first reversing valve comprises 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, and the first oil inlet is used to communicate with the hydraulic pump; The second reversing valve comprises 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; Wherein, 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 a first working position and the second reversing valve is in a 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 flow back to the third pipeline; The arm being unloaded means that the load of the arm is less than a preset load value.

2. The control valve assembly 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 heavy-load 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 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 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 a heavy-load, small-angle retracted state, 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 port. The sixth working oil port is used to communicate with the oil inlet chamber of the boom tilting cylinder, and the third oil inlet port is used to communicate with the hydraulic pump.

5. A hydraulic system, characterized in that: include: Boom extension cylinder; Boom tilting cylinder; Fuel tank assembly; A control valve assembly as claimed in 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 cylinder, the rod chamber of the boom telescopic cylinder, and the oil inlet chamber of the boom tilting cylinder; An angle acquisition unit, used to acquire the tilt angle of the boom; A boom extension position acquisition unit, used for acquiring the boom extension position; A controller, electrically connected to the pressure acquisition unit, the angle acquisition unit, and the load acquisition unit; Among them, 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 state 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 as claimed in claim 6.

8. A method for controlling the telescopic arm of a front crane, characterized in that: The boom of the front crane is telescopically controlled by the control valve group according to any one of claims 1 to 4, and the boom telescopic control method comprises: Obtain the inclination angle of the boom and the extension position of the boom, and obtain the pressure 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 telescopic cylinder of the boom is calculated according to the inclination angle of the boom and the load of the boom; The working state of the boom is determined 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: 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: 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 located at the first working position, and the second reversing valve is controlled to be located at 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 control method according to claim 8, characterized in that: Judging the working state of the boom according to the tilt angle of the boom 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 comprises: When the actual elevation angle of the boom is less than the preset elevation angle value of the boom in the retracted state, and the total resistance overcome by the boom telescopic cylinder in the retraction is greater than the preset total retraction resistance value, the boom is judged to be in a heavy-load small elevation angle retracted state, and the first reversing valve is controlled to be located in the second working position, and the second reversing valve is controlled to be located in the third working position; When the boom is in the retracted state, when 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 retracting boom telescopic cylinder is less than the preset total retraction resistance value, the boom is judged to be in a heavy-loaded and large-angle retracted 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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