Synchronous lifting hydraulic system and tower crane

Abstract

This invention belongs to the field of hydraulic technology for engineering machinery, and discloses a synchronous lifting hydraulic system and a tower crane. The synchronous lifting hydraulic system includes a first and a second hydraulic cylinder, a drain oil circuit, and first and second pilot drive oil circuits. The drain oil circuit is equipped with a hydraulically controlled proportional valve. Its first inlet is connected to the high-pressure oil circuit in the working oil circuit of the first cylinder via a first inlet oil circuit, and its second inlet is connected to the high-pressure oil circuit in the working oil circuit of the second cylinder via a second inlet oil circuit. The first pilot drive oil circuit connects the working oil circuit of the first cylinder to the first control terminal of the hydraulically controlled proportional valve and drives the first valve core end of the proportional valve spool to move towards the second valve core end. The second pilot drive oil circuit connects the working oil circuit of the second cylinder to the second control terminal and drives the second valve core end to move towards the first valve core end. This invention allows excess oil in the working oil circuit of the cylinder with a larger flow rate to return through the drain oil circuit, thereby ensuring synchronous lifting of the two cylinders.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic technology for engineering machinery, specifically relating to a synchronous lifting hydraulic system and a tower crane. Background Technology

[0002] During construction, as the building's height changes, the tower crane's working height needs to be adjusted to meet operational requirements. Currently, self-climbing tower cranes utilize their own jacking systems to continuously increase or decrease the working height according to construction needs.

[0003] As construction demands increasingly rapid lifting speeds, tower cranes need to possess higher lifting speeds and strokes, while simultaneously ensuring stable and safe lifting during the process. The synchronization of lifting operations for large tower cranes plays a decisive role in lifting safety. Summary of the Invention

[0004] To address the aforementioned deficiencies or shortcomings, this invention discloses a synchronous lifting hydraulic system and tower crane to ensure the synchronous lifting of the hydraulic cylinders and improve the safety and reliability of the lifting operation.

[0005] To achieve the above objectives, the present invention provides a synchronous lifting hydraulic system, comprising:

[0006] The first hydraulic cylinder is connected to the working oil circuit of the first hydraulic cylinder;

[0007] The second hydraulic cylinder is connected to the working oil circuit of the second hydraulic cylinder;

[0008] The oil drain circuit includes a hydraulically controlled proportional valve with a proportional valve core. One side of the hydraulically controlled proportional valve has an oil drain port for oil return, and the other side has a first oil inlet and a second oil inlet that are switched and connected to the oil drain port. The first oil inlet is connected to the high-pressure oil circuit in the working oil circuit of the first cylinder through a first oil inlet circuit, and the second oil inlet is connected to the high-pressure oil circuit in the working oil circuit of the second cylinder through a second oil inlet circuit.

[0009] The first pilot drive oil circuit connects the first cylinder working oil circuit to the first control terminal of the hydraulic proportional valve, and is used to drive the first valve core end of the proportional valve core to move toward the second valve core end; and

[0010] The second pilot drive oil circuit connects the working oil circuit of the second oil cylinder to the second control terminal of the hydraulic proportional valve, and drives the second valve core end of the proportional valve core to move toward the first valve core end.

[0011] In some embodiments, the synchronous lifting hydraulic system includes:

[0012] A first oil pump and a second oil pump, wherein the first oil pump independently drives the first oil cylinder and the second oil pump independently drives the second oil cylinder;

[0013] The first throttling element is installed in the working oil circuit of the first oil cylinder;

[0014] The second throttling element is installed in the working oil circuit of the first cylinder;

[0015] A first hydraulic drive valve is disposed between the first pilot drive oil circuit and the first valve of the proportional valve core and drives the proportional valve core to move toward the second valve core end with a first driving force.

[0016] The second hydraulic drive valve is disposed between the second pilot drive oil circuit and the second valve of the proportional valve core and drives the proportional valve core to move toward the first valve core end with the second driving force.

[0017] Wherein, the first driving force is proportional to the pressure difference between the front and rear ends of the first throttling element, and the second driving force is proportional to the pressure difference between the front and rear ends of the second throttling element.

[0018] In some embodiments, the first hydraulically driven valve includes:

[0019] The first drive piston rod is connected to the first valve core end;

[0020] The rodless chamber of the first drive valve is connected to the throttling front oil circuit of the first throttling element;

[0021] The first drive valve has a rod chamber, which is connected to the throttling rear oil passage of the first throttling element;

[0022] Furthermore, the second hydraulically driven valve includes:

[0023] The second drive piston rod is connected to the end of the second valve core;

[0024] The rodless chamber of the second drive valve is connected to the throttling front oil circuit of the second throttling element;

[0025] The second drive valve has a rod chamber, which is connected to the throttling rear end oil passage of the second throttling element.

[0026] In some embodiments, the synchronous lifting hydraulic system includes:

[0027] The main oil pump drives the first oil cylinder and the second oil cylinder in parallel.

[0028] The first throttling element is installed in the working oil circuit of the first oil cylinder;

[0029] The second throttling element is installed in the working oil circuit of the first cylinder;

[0030] The first pilot drive oil circuit is connected to the throttling rear end of the first throttling element, and the second pilot drive oil circuit is connected to the throttling rear end of the second throttling element.

[0031] In some embodiments, the synchronous lifting hydraulic system includes:

[0032] The first directional valve is connected to one side of the first directional valve via the first main pump delivery circuit, and the other side of the first directional valve is connected to the working oil circuit of the first cylinder.

[0033] The second directional valve is connected to one side of the second directional valve via the second main pump oil delivery circuit, and the other side of the second directional valve is connected to the working oil circuit of the second cylinder.

[0034] Alternatively, the synchronous lifting hydraulic system includes a main directional valve, the main oil pump is connected to one side of the main directional valve through a main pumping oil circuit, and the other side of the main directional valve is connected in parallel to the working oil circuit of the first cylinder and the working oil circuit of the second cylinder.

[0035] In some embodiments, the first cylinder and the second cylinder, the first throttling element and the second throttling element, and the first hydraulic drive valve and the second hydraulic drive valve are all identical hydraulic devices.

[0036] In some embodiments, the first throttling element is disposed in the first rodless chamber oil passage of the first cylinder working oil passage, and the second throttling element is disposed in the second rodless chamber oil passage of the second cylinder working oil passage.

[0037] In some embodiments, the drain oil passage is further provided with:

[0038] The first shuttle valve has its outlet connected to the first inlet oil circuit, and its two comparison ports are respectively connected to the rod chamber oil circuit and the rodless chamber oil circuit of the first cylinder in the working oil circuit of the first cylinder.

[0039] The second shuttle valve has its outlet connected to the second inlet oil circuit, and its two comparison ports are respectively connected to the rod chamber oil circuit and the rodless chamber oil circuit of the second cylinder in the working oil circuit of the second cylinder.

[0040] In some embodiments, one of the comparison ports of the first shuttle valve is connected to the throttling front end of the first throttling element, and one of the comparison ports of the second shuttle valve is connected to the throttling front end of the second throttling element.

[0041] In some embodiments, the hydraulic proportional valve is a three-position three-way directional valve with an intermediate stop position.

[0042] In some embodiments, the drain circuit is further provided with an auxiliary reversing valve, which is used to switch the first oil inlet circuit and the second oil inlet circuit to the first oil inlet and the second oil inlet of the hydraulic proportional valve.

[0043] Furthermore, the present invention also provides a tower crane, the tower crane including the synchronous lifting hydraulic system according to the present invention described above, wherein the first cylinder and the second cylinder are the double lifting cylinders of the tower crane.

[0044] In the tower crane and its synchronous jacking hydraulic system of the present invention, an oil drain circuit with a hydraulically controlled proportional valve, a first pilot drive circuit connected to the working oil circuit of the first cylinder, and a second pilot drive circuit connected to the working oil circuit of the second cylinder are added. The pilot drive circuit from the working oil circuit of the cylinder controls the valve position of the hydraulically controlled proportional valve. By coordinating the reversing valve position, some of the excess oil in the working oil circuit of the cylinder with a larger flow rate can be returned through the oil drain circuit, thereby ensuring that the flow rates on both sides are equal and maintaining synchronous jacking of the two cylinders, thus effectively improving the safety and reliability of the jacking operation.

[0045] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0046] The accompanying drawings are provided to illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 This is a schematic diagram of a single-cylinder lifting structure in a conventional self-climbing tower crane.

[0048] Figure 2 This is a schematic diagram of a dual-cylinder lifting structure in a conventional self-climbing tower crane;

[0049] Figure 3 This is a hydraulic schematic diagram of a conventional self-climbing tower crane with a dual-cylinder lifting structure.

[0050] Figure 4 A hydraulic schematic diagram of a synchronous lifting hydraulic system according to a first embodiment of the present invention;

[0051] Figure 5 for Figure 4 A magnified view of the dashed box area in the image;

[0052] Figure 6 This is a hydraulic schematic diagram of a synchronous lifting hydraulic system according to a second embodiment of the present invention;

[0053] Figure 7 This is a hydraulic schematic diagram of a synchronous lifting hydraulic system according to a third embodiment of the present invention.

[0054] Explanation of reference numerals in the attached figures

[0055] 1. First hydraulic cylinder 2. Second hydraulic cylinder

[0056] 3. Hydraulic lock 4. Hydraulic proportional valve

[0057] 5 First throttling element 6 Second throttling element

[0058] 7 First hydraulic drive valve 8 Second hydraulic drive valve

[0059] 9 Auxiliary directional valve 10 Main directional valve

[0060] 11 First shuttle valve 12 Second shuttle valve

[0061] 13 First directional control valve 14 Second directional control valve

[0062] 15 Safety valve 16 Shut-off valve

[0063] 17 First oil pump 18 Second oil pump

[0064] 19 Electric motor 20 Main oil pump

[0065] 30 Variable control valve 41 Proportional valve core

[0066] X1 First pilot drive oil circuit X2 Second pilot drive oil circuit

[0067] H11 First cylinder rodless chamber oil circuit; H12 First cylinder rod chamber oil circuit

[0068] H21 Second cylinder rodless chamber oil circuit; H22 Second cylinder rod chamber oil circuit

[0069] A. First oil inlet B. Second oil inlet

[0070] C Drain port L1 Drain oil passage

[0071] G1 First lifting load G2 Second lifting load

[0072] 101 Foundation 102 Standard section of tower body

[0073] 103 Climbing frame; 104 Upper part of tower crane

[0074] 105 Rollers 106 Steps

[0075] 107 Main lifting cylinder; 109 Hanging plate

[0076] 110 Mechanical connection structure 111 Import system

[0077] 112 Standard tower section to be imported 113 Auxiliary hydraulic cylinder Detailed Implementation

[0078] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0079] The synchronous lifting hydraulic system and tower crane according to the present invention are described below with reference to the accompanying drawings.

[0080] A tower crane's jacking system generally includes a jacking hydraulic system, climbing frame, jacking beam, hanging plates, steps mounted on standard sections, and a guide system. The jacking hydraulic system mainly includes jacking cylinders, control valves, oil tanks, safety valves, hydraulic lines, and hydraulic accessories. For example... Figure 1 In the single-cylinder lifting structure of the self-climbing tower crane shown, the tower crane includes a tower body extending vertically upward from the foundation 101 and a tower upper section 104 located at the top of the tower body. The tower body includes multiple standard tower sections 102 stacked upwards. The lifting system of the tower crane is located in the tower body section and generally includes a lifting hydraulic system and structural components such as a climbing frame 103, steps 106, and hanging plates 109. The climbing frame 103 is fitted onto the outside of the standard tower section 102 and can move upwards or downwards along the main chord outside the standard tower section 102 via guide rollers 105.

[0081] Figure 1 The diagram shows a single-cylinder lifting structure. For large tower cranes, due to the larger lifting load, it is increasingly necessary to use two or more cylinders for lifting, for example... Figure 2 The tower crane employs symmetrically arranged dual hydraulic cylinders on both sides for jacking. This multi-cylinder jacking system can ensure sufficient jacking force during jacking, but it also presents the problem of synchronizing the jacking of multiple cylinders. It is necessary to ensure that the jacking of multiple hydraulic cylinders is synchronized, and the jacking speed of the two hydraulic cylinders must be adjusted at any time during the jacking operation to ensure that the jacking displacement on both sides is consistent, so that the tower crane will not tilt.

[0082] Regardless of whether a single-cylinder or double-cylinder lifting structure is used, when the tower crane needs to be raised, the first step is to position the hanging plate 109 onto the step 106 of the next standard section 102 of the tower crane. The mechanical connection structure 110 between the upper part 104 of the tower crane (i.e., the lifting load) and the lower standard section 102 is then released. At this point, the lifting load is mechanically connected to the climbing frame 103. Next, the lifting hydraulic system is activated, and oil enters the rodless chamber of the main lifting cylinder 107. Its piston rod head connects to the lifting beam and is supported on the step 106 of the lower standard section 102 of the tower crane. The lifting load and the climbing frame 103 are supported by the main lifting cylinder 107. Maintaining this state, the piston rod extends, the outer cylinder rises, and the lifting load and climbing frame 103 rise a certain distance. After reaching the appropriate height, the hanging plate 109 is hooked onto the next step 106 and mechanically positioned, thus completing the lifting operation for one step. Among them, the auxiliary hydraulic cylinder 113 is used to assist the main lifting hydraulic cylinder 107.

[0083] At this time, the upper load and climbing frame 103 are reliably connected and positioned with the steps 106 of the lower tower standard section 102 through the hanging plate 109, and the aforementioned lifting distance, i.e., one step spacing, is left between the lifting load and climbing frame 103 and the lower tower standard section 102.

[0084] Furthermore, such as Figure 3 As shown, the lifting hydraulic system switches the oil supply through the reversing valve, allowing oil to enter the rod chamber of the main lifting cylinder 107. The piston rod retracts, the piston rod head connects with the lifting beam, and enters the next step, preparing for the second lifting step. Repeating the above operation, the upper lifting load and climbing frame 103 can be raised to a height higher than one standard tower section 102. At this time, the standard tower section 112 to be introduced can be loaded through the introduction system 111, and positioned, connected, and locked, thus completing one lifting operation of the tower crane. The tower lowering operation is similar to the above lifting operation. In the lifting operation, for tower cranes where the standard tower sections 102 are connected by tenons, since there is embedded tenon length between the standard tower sections 102, the final "positioning" of the standard tower section 112 to be introduced requires the "tenon insertion" operation step. Similarly, for the tower lowering operation, when the standard tower section to be introduced is led out, the "tenon disengagement" operation also needs to be completed.

[0085] For large tower cranes, due to the large lifting load, two or more hydraulic cylinders are required for lifting; the lifting cylinders are arranged in different positions on the tower crane, such as... Figure 2 As shown, in addition to ensuring sufficient lifting force, it is crucial to ensure the synchronization of the two hydraulic cylinders during jacking to guarantee a smooth and safe process. Therefore, the synchronicity of jacking in large tower cranes plays a decisive role in jacking safety.

[0086] visible, Figure 3The existing multi-cylinder lifting hydraulic system shown has several drawbacks. First, due to uneven load distribution among the cylinders, asynchronous lifting occurs from left to right, causing the tower crane to tilt and increasing the risk of accidents. Second, to ensure synchronized lifting from left to right, a variable regulating valve 30 needs to be installed in the system. Figure 3 As shown, adjustments can be made by adding throttle valves, speed control valves, or flow divider / combiner valves to the oil circuits of the rodless or rod chambers of the two cylinders. However, a common drawback is that after synchronization is achieved once, adjustments are needed again for subsequent use due to changes in load conditions. Such adjustments often require hydraulic specialists, which are beyond the capabilities of ordinary lifting workers. Furthermore, due to the full-flow regulation, the large flow rate generates significant heat. Some solutions employ enlarged single-cylinder designs, resulting in an oversized tower crane structure and an unreasonable layout. Alternatively, two cylinders may be placed on the same side, with the cylinder barrels welded or mechanically rigidly connected. This makes it impossible to ensure synchronization during tower lowering operations; the welded or rigidly connected cylinder barrels also have poor manufacturability and are difficult to maintain. Additionally, some solutions use electro-hydraulic proportional valves, which can ensure synchronization, but require sensors and controllers. Electro-hydraulic proportional valve systems are expensive to operate and maintain.

[0087] In view of this, to ensure the synchronization of cylinder lifting and improve the safety and reliability of lifting operations, this invention discloses a novel synchronous lifting hydraulic system. For example... Figure 4 , Figure 5 In the embodiment shown, the synchronous lifting hydraulic system includes:

[0088] First oil cylinder 1 is connected to the working oil circuit of the first oil cylinder;

[0089] The second hydraulic cylinder 2 is connected to the working oil circuit of the second hydraulic cylinder;

[0090] The oil drain circuit L1 is equipped with a hydraulic proportional valve 4 with a proportional valve core 41. One side of the hydraulic proportional valve 4 is provided with an oil drain port C for oil return, and the other side is provided with a first oil inlet A and a second oil inlet B that are switched and connected to the oil drain port C. The first oil inlet A is connected to the high oil pressure oil circuit in the working oil circuit of the first oil cylinder through a first oil inlet circuit, and the second oil inlet B is connected to the high oil pressure oil circuit in the working oil circuit of the second oil cylinder through a second oil inlet circuit.

[0091] The first pilot drive oil circuit X1 connects the working oil circuit of the first oil cylinder to the first control terminal of the hydraulic proportional valve 4, and is used to drive the first valve core end of the proportional valve core 41 to move toward the second valve core end; and

[0092] The second pilot drive oil circuit X2 connects the working oil circuit of the second oil cylinder to the second control terminal of the hydraulic proportional valve 4, and drives the second valve core end of the proportional valve core 41 to move toward the first valve core end.

[0093] This invention aims to regulate and maintain the synchronization of two hydraulic cylinders. Therefore, an oil drain circuit is added to promptly discharge excess oil from both cylinders, thereby ensuring their synchronization. Specifically, the oil drain circuit L1 is equipped with a hydraulically controlled proportional valve 4 with a proportional valve core 41. The opening size of the hydraulically controlled proportional valve 4 is controlled by a pilot drive oil circuit from the working oil circuit of the cylinders, thereby draining excess oil from both branches and ensuring equal flow rates on both sides. Ultimately, this maintains the synchronous lifting of the two hydraulic cylinders.

[0094] exist Figure 4 In this embodiment, the synchronous lifting hydraulic system includes:

[0095] First oil pump 17 and second oil pump 18, the first oil pump 17 independently drives the first oil cylinder 1, and the second oil pump 18 independently drives the second oil cylinder 2;

[0096] The first throttling element 5 is installed in the working oil circuit of the first oil cylinder;

[0097] The second throttling element 6 is installed in the working oil circuit of the second oil cylinder;

[0098] The first hydraulic drive valve 7 is disposed between the first pilot drive oil circuit X1 and the first valve of the proportional valve core 41 and drives the proportional valve core 41 to move toward the second valve core end with the first driving force.

[0099] The second hydraulic drive valve 8 is disposed between the second pilot drive oil circuit X2 and the second valve of the proportional valve core 41 and drives the proportional valve core 41 to move toward the first valve core end with the second driving force.

[0100] The first driving force is proportional to the pressure difference between the front and rear ends of the first throttling element 5, and the second driving force is proportional to the pressure difference between the front and rear ends of the second throttling element 6.

[0101] In this embodiment, because the system employs a dual-pump independent system, the movement speed of the cylinders on both sides depends on the flow rate of each branch, such as the volumetric efficiency of the pump and the flow characteristics of each valve. This ultimately results in the flow rate Q1 reaching the first cylinder 1 not being equal to the flow rate Q2 reaching the second cylinder 2, leading to different cylinder movement speeds and asynchrony between the two cylinders. When the lifting loads of the left and right cylinders are inconsistent, i.e., the first lifting load G1 is different from the second lifting load G2, the system can automatically increase the working pressure to ensure normal cylinder movement due to the independent drive of the two pumps.

[0102] Since the flow rate at the valve orifice is proportional to the nth power of the pressure difference (n<1, typically n=0.5 at the valve orifice), the flow rate passes through the fixed throttling element, and the pressure difference at both ends can sense the flow rate of the two cylinder circuits. To eliminate the asynchronous movement of the cylinders caused by Q1≠Q2, this embodiment of the system is equipped with two throttling elements with identical geometric dimensions, which can sense the flow rate of the working oil circuits of the left and right cylinders. The pressure difference generated by the oil throttling orifice corresponds to the flow rate. Oil pipes are connected before and after the throttling element, i.e., the pilot drive oil circuit. The pressure difference between the inlet and outlet of the throttling element (i.e., the pressure difference before and after throttling) can promptly reflect the flow rate. The two oil pipes are connected to both ends of the hydraulic drive valve, so that the pressure difference can drive the valve core of the hydraulic drive valve to move, thereby driving the proportional valve core 41 to move, opening the drain oil circuit L1, and draining the excess oil in the two branches.

[0103] In other words, the pressure difference between the two ends of the two throttling elements can be diverted to the two ends of the hydraulic drive valve, thereby driving the hydraulic proportional valve and controlling the opening size of the hydraulic proportional valve. This can drain the excess oil in the two branches, ensuring that the flow on both sides is equal, and ultimately keeping the two cylinders lifting synchronously.

[0104] To achieve the above-mentioned linkage drive, in this embodiment, as follows: Figure 5 As shown, the first hydraulically driven valve 7, as an example, includes:

[0105] The first drive piston rod is connected to the first valve core end;

[0106] The rodless chamber of the first drive valve is connected to the throttling front oil circuit of the first throttling element 5;

[0107] The first drive valve has a rod chamber, which is connected to the oil circuit at the throttling end of the first throttling element 5;

[0108] Similarly, the second hydraulic actuation valve 8 includes:

[0109] The second drive piston rod is connected to the end of the second valve core;

[0110] The rodless chamber of the second drive valve is connected to the throttling front oil circuit of the second throttling element 6;

[0111] The second drive valve has a rod chamber, which is connected to the throttling rear oil passage of the second throttling element 6.

[0112] Figure 5 As can be seen, one first pilot drive oil circuit X1 connected to the throttling front end of the first throttling element 5 is connected to the rodless chamber of the first hydraulic drive valve 7, and another first pilot drive oil circuit X1 connected to the throttling rear end of the first throttling element 5 is connected to the rod chamber of the first hydraulic drive valve 7. The valve core of the first hydraulic drive valve 7 has different areas at both ends, which has an amplification effect and can improve the flow perception.

[0113] The valve core of the first hydraulic drive valve 7 can be mechanically connected to the proportional valve core 41 of the hydraulic proportional valve 4, or they can be integrally formed. Therefore, the first hydraulic drive valve 7 can drive the hydraulic proportional valve 4 to open. When the hydraulic proportional valve 4 opens, one of the first oil inlet A and the second oil inlet B is connected to the oil drain port C to drain excess oil until the hydraulic proportional valve 4 closes, maintaining a new balance and synchronizing the movement of the two cylinders.

[0114] It should be noted that the hydraulic drive valve is not limited to the valve body structure shown in the figure. Various intermediate drive valves that can apply the pressure difference between the two ends of the throttling element brought by the pilot drive oil circuit to the proportional valve core 41 of the hydraulic proportional valve 4 are all within the protection scope of this invention.

[0115] Considering its application in a synchronous lifting system, in this embodiment, the first cylinder 1 and the second cylinder 2, the first throttling element 5 and the second throttling element 6, and the first hydraulic drive valve 7 and the second hydraulic drive valve 8 should all be identical hydraulic devices to provide a basis for synchronous control of the two cylinders.

[0116] In this embodiment, such as Figure 4 , Figure 5 As shown, optionally, the first throttling element 5 is disposed in the first rodless chamber oil passage H11 of the first cylinder working oil circuit, and the second throttling element 6 is disposed in the second rodless chamber oil passage H21 of the second cylinder working oil circuit. Of course, those skilled in the art will understand that, in the case of changes in the connection relationship with the hydraulic drive valve, the throttling element may also be disposed in another oil passage in the cylinder working oil circuit.

[0117] Furthermore, in this embodiment, the oil drain line L1 is also provided with:

[0118] The first shuttle valve 11 has an oil outlet connected to the first oil inlet circuit, and its two comparison ports are respectively connected to the first oil cylinder rod chamber oil circuit H12 and the first oil cylinder rodless chamber oil circuit H11 in the first oil cylinder working oil circuit.

[0119] The second shuttle valve 12 has its outlet connected to the second oil inlet circuit, and its two comparison ports are respectively connected to the rod chamber oil circuit H22 and the rodless chamber oil circuit H21 of the second cylinder working oil circuit.

[0120] In this way, by setting up a shuttle valve, the oil in the high-pressure oil line of the hydraulic cylinder working oil circuit can be led out as excess oil and drained through the drain oil circuit L1.

[0121] exist Figure 4As can be seen, one comparison port of the first shuttle valve 11 is connected to the throttling front end of the first throttling element 5, and one comparison port of the second shuttle valve 12 is connected to the throttling front end of the second throttling element 6. That is, excess flow in the working oil circuit of the hydraulic cylinder is discharged more quickly before throttling, reducing the impact on the throttling element.

[0122] As an example, the hydraulic proportional valve 4 in this embodiment is a three-position three-way directional valve with an intermediate stop position. Of course, those skilled in the art will understand that the hydraulic proportional valve 4 can also adopt more valve positions and more complex valve structure, which will not be elaborated here.

[0123] Specifically, in Figure 4 , Figure 5 In this implementation, when the oil flow into the working oil circuits of both cylinders is equal, the two throttling elements have identical geometric dimensions, resulting in the same pressure difference. Therefore, the proportional valve core 41 of the hydraulic proportional valve experiences consistent force on both sides and will not move, thus closing both proportional valves. The two cylinders then operate at the same speed.

[0124] When the flow rates Q1 ≠ Q2, for example, Q1 > Q2, then Q1 and Q2 will generate pressure differences ΔP1 and ΔP2 respectively when passing through the orifice; see [link / reference]. Figure 5 That is, △P1=Paj1-Paj2, △P2=Pbj1-Pbj2; obviously, △P1>△P2.

[0125] like Figure 4 , Figure 5 As shown, the pressures Paj1 and Paj2 at the front and rear ends of the first throttling element 5 on the left are introduced into the valve cores of the first hydraulic drive valve 7, respectively; the pressures Pbj1 and Pbj2 at the front and rear ends of the second throttling element 6 on the right are introduced into the valve cores of the second hydraulic drive valve 8, respectively. Because the areas at both ends of the valve cores of the hydraulic drive valves are inconsistent, amplified pressure difference is generated, increasing sensitivity. Since ΔP1 > ΔP2, the hydraulic proportional valve 4 moves to the right and opens the left valve position. A portion of the high-pressure oil in the working oil circuit of the first cylinder flows out through the first shuttle valve 11 and the drain port C of the hydraulic proportional valve 4 until Q1 = Q2, maintaining a new balance. This ensures that the flow rates of the left and right cylinder branches are equal, the lifting speed is consistent, and asynchronous lifting does not occur.

[0126] The above describes the operating condition where oil enters the rodless chamber of the hydraulic cylinder. If oil enters the rod chamber and exits the rodless chamber, synchronous movement of the left and right cylinders can still be ensured. In this case, an auxiliary directional valve 9 is specially installed in the drain circuit L1. The auxiliary directional valve 9 is used to switch the first and second oil inlet circuits to the first inlet A and the second inlet B of the hydraulic proportional valve 4. When oil enters the rod chamber of the hydraulic cylinder, because the opening direction of the hydraulic proportional valve 4 is opposite... Figure 4 The auxiliary directional valve 9 in the middle should be switched.

[0127] Due to the oil inlet of the rod chamber of the oil cylinder, the oil outlet of the rodless chamber is about twice the oil inlet volume. The pressure difference passing through the throttling element is about four times that of the rodless chamber, playing a significant amplifying role. When the flow rates of the two branches are different, the hydraulic drive valve can also push the hydraulic control proportional valve to open, drain the excess flow, and maintain a new balance.

[0128] In Figure 4 、 Figure 5 In the first embodiment shown in

[0129] As Figure 6 In the second embodiment described in

[0130] The main oil pump 20 drives the first oil cylinder 1 and the second oil cylinder 2 in parallel;

[0131] The first throttling element 5 is arranged in the working oil circuit of the first oil cylinder;

[0132] The second throttling element 6 is arranged in the working oil circuit of the second oil cylinder;

[0133] Among them, the first pilot drive oil circuit X1 is connected to the throttling rear end of the first throttling element 5, and the second pilot drive oil circuit X2 is connected to the throttling rear end of the second throttling element 6.

[0134] When the main oil pump is driven alone, the working oil circuits of the left and right oil cylinders are in parallel. The movement speed of the oil cylinders is determined by the loads of the left and right oil cylinders, that is, the first jacking load G1 and the second jacking load G2. The flow rate of the working oil circuit of the oil cylinder with a large load is small, and the movement speed of the oil cylinder is slow; the flow rate of the working oil circuit of the oil cylinder with a small load is large, and the movement speed of the oil cylinder is fast. In order to ensure the synchronous movement of the first oil cylinder 1 and the second oil cylinder 2, it is necessary to drain part of the oil in the working oil circuit of the oil cylinder with a large flow rate.

[0135] Taking the oil inlet of the rodless chamber as an example, if G1 > G2, then Q1 < Q2, and the second oil cylinder 2 on the right moves faster, and it is necessary to drain part of the oil in the working oil circuit of the second oil cylinder. Compared with Figure 4The hydraulic drive valve is removed, and the first pilot drive oil circuit X1 is directly connected to the throttling end of the first throttling element 5, and the second pilot drive oil circuit X2 is connected to the throttling end of the second throttling element 6. The oil pressure at the throttling end of the first throttling element 5 is P1, and the oil pressure at the throttling end of the second throttling element 6 is P2. Since G1 > G2, it is obvious that P1 > P2. In this case, the two control terminals of the hydraulic proportional valve 4 are directly introduced. By switching the movement of the proportional valve core 41, some hydraulic oil is drained from the working oil circuit of the second cylinder until the flow rates of the working oil circuits of the first and second cylinders are equal, and a new balance is re-established. Similarly, if there is oil entering the rod chamber, automatic synchronization can also be performed by simply changing the valve position of the auxiliary directional valve 9.

[0136] In the second embodiment, the synchronous lifting hydraulic system includes:

[0137] The first directional valve 13 is connected to one side of the main oil pump 20 through the first main pumping oil circuit, and the other side of the first directional valve 13 is connected to the working oil circuit of the first oil cylinder.

[0138] The second directional valve 14 is connected to one side of the main oil pump 20 through the second main pumping oil circuit, and the other side of the second directional valve 14 is connected to the working oil circuit of the second oil cylinder.

[0139] therefore, Figure 6 The first and second hydraulic cylinders can be controlled to extend and retract independently. Figure 4 The device also includes a first directional valve 13 and a second directional valve 14, allowing the two cylinders to be controlled independently. However, since the main purpose of the invention is to synchronize the two cylinders, they can obviously share the main directional valve. Therefore, if... Figure 7 As shown, the synchronous lifting hydraulic system may include a main directional valve 10, a main oil pump 20 connected to one side of the main directional valve 10 through a main pumping oil circuit, and the other side of the main directional valve 10 connected in parallel to the working oil circuit of the first oil cylinder and the working oil circuit of the second oil cylinder.

[0140] In addition, the synchronous lifting hydraulic system is also equipped with safety valve 5 for setting the maximum operating oil pressure of the system, hydraulic lock 3 for locking and maintaining the extended state of the oil cylinder, etc. The settings and functions are well known to those skilled in the art, and will not be described in detail here.

[0141] In addition, this invention also discloses a tower crane, which includes the aforementioned synchronous lifting hydraulic system, wherein the first cylinder 1 and the second cylinder 2 are the tower crane's dual lifting cylinders. Clearly, the tower crane's lifting system has a better synchronous lifting effect.

[0142] In summary, in the synchronous lifting hydraulic system of this invention, the lifting speed of the left and right cylinders is independent of load changes, and the lifting speed of the two cylinders is consistent. When using one oil pump to independently drive each cylinder, as long as the load on the working oil circuit of the left and right cylinders is lower than the safety valve pressure, the normal synchronous lifting of the left and right branches can be guaranteed. The system operates smoothly regardless of load changes; load changes caused by tower structure deformation, wind speed changes, and roller clearance changes during the lifting process will not affect the lifting synchronization. Because this invention incorporates a throttling element, when the flow rate changes in the working oil circuit of the cylinder due to pipeline leakage and reduced main pump volumetric efficiency, it can accurately detect changes in the flow rate of the cylinder branch and automatically adjust to ensure consistent flow rates in both circuits. Moreover, due to the use of a hydraulic amplification element, the high sensitivity makes it more suitable for low-flow systems. Because it also uses a valve core with an unequal area ratio, sufficient thrust can be generated to open the hydraulic proportional valve even when the flow rate and pressure difference are small. The throttling element used in this system can sense changes in the flow rate of each branch and automatically adjust the proportional opening based on the pressure difference, eliminating the need for manual adjustment. In emergency situations, a single pump can be used, ensuring high system reliability. For example, if the right oil pump fails, it can be disconnected; by opening the shut-off valve, the entire system can be supplied with oil by the left oil pump, allowing the lifting operation to be completed. Compared to existing technologies, this invention uses a manual directional valve and a hydraulically controlled proportional valve to ensure synchronization of the lifting cylinders; it eliminates the need for displacement sensors, controllers, electro-hydraulic proportional valves, and other hydraulic components, resulting in a simpler and lower-cost system. Furthermore, due to the adoption of a bypass low-flow scheme, the system experiences minimal impact and offers stable control.

[0143] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0144] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0145] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0146] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A synchronous lifting hydraulic system, characterized in that, The synchronous lifting hydraulic system includes: The first oil cylinder (1) is connected to the working oil circuit of the first oil cylinder equipped with the first throttling element (5); The second oil cylinder (2) is connected to the working oil circuit of the second oil cylinder equipped with the second throttling element (6); The oil drain circuit (L1) is provided with a hydraulic proportional valve (4) having a proportional valve core (41). One side of the hydraulic proportional valve (4) is provided with an oil drain port (C) for oil return, and the other side is provided with a first oil inlet (A) and a second oil inlet (B) that are switched and connected to the oil drain port (C). The first oil inlet (A) is connected to the high oil pressure oil circuit in the working oil circuit of the first cylinder through a first oil inlet circuit, and the second oil inlet (B) is connected to the high oil pressure oil circuit in the working oil circuit of the second cylinder through a second oil inlet circuit. The first shuttle valve (11) has an oil outlet connected to the first oil inlet circuit, and the two comparison ports of the first shuttle valve (11) are respectively connected to the first cylinder rod chamber oil circuit (H12) and the first cylinder rodless chamber oil circuit (H11) in the first cylinder working oil circuit. The second shuttle valve (12) has its outlet connected to the second oil inlet circuit, and its two comparison ports are respectively connected to the rod chamber oil circuit (H22) and the rodless chamber oil circuit (H21) of the second cylinder working circuit. The first pilot drive oil circuit (X1) connects the first throttling element (5) of the first cylinder working oil circuit to the first control end of the hydraulic proportional valve (4), and is used to drive the first valve core end of the proportional valve core (41) to move toward the second valve core end; and The second pilot drive oil circuit (X2) connects the second throttling element (6) of the second oil cylinder working oil circuit to the second control end of the hydraulic proportional valve (4), and drives the second valve core end of the proportional valve core (41) to move toward the first valve core end.

2. The synchronous lifting hydraulic system according to claim 1, characterized in that, The synchronous lifting hydraulic system includes: A first oil pump (17) and a second oil pump (18), wherein the first oil pump (17) independently drives the first oil cylinder (1) and the second oil pump (18) independently drives the second oil cylinder (2); A first hydraulic drive valve (7) is disposed between the first pilot drive oil circuit (X1) and the first valve of the proportional valve core (41) and drives the proportional valve core (41) to move toward the second valve core end with a first driving force. The second hydraulic drive valve (8) is disposed between the second pilot drive oil circuit (X2) and the second valve of the proportional valve core (41) and drives the proportional valve core (41) to move toward the first valve core end with the second driving force. The first driving force is proportional to the pressure difference between the front and rear ends of the first throttling element (5), and the second driving force is proportional to the pressure difference between the front and rear ends of the second throttling element (6).

3. The synchronous lifting hydraulic system according to claim 2, characterized in that, The first hydraulic drive valve (7) includes: The first drive piston rod is connected to the first valve core end; The rodless chamber of the first drive valve is connected to the throttling front oil circuit of the first throttling element (5); The first drive valve has a rod chamber, which is connected to the throttling rear oil passage of the first throttling element (5); Furthermore, the second hydraulic actuation valve (8) includes: The second drive piston rod is connected to the end of the second valve core; The rodless chamber of the second drive valve is connected to the throttling front oil circuit of the second throttling element (6); The second drive valve has a rod chamber, which is connected to the throttling rear end oil passage of the second throttling element (6).

4. The synchronous lifting hydraulic system according to claim 1, characterized in that, The synchronous lifting hydraulic system includes: The main oil pump (20) drives the first oil cylinder (1) and the second oil cylinder (2) in parallel. The first pilot drive oil circuit (X1) is connected to the throttling end of the first throttling element (5), and the second pilot drive oil circuit (X2) is connected to the throttling end of the second throttling element (6).

5. The synchronous lifting hydraulic system according to claim 4, characterized in that, The synchronous lifting hydraulic system includes: The first directional valve (13) is connected to one side of the first directional valve (13) through the first main pumping oil circuit, and the other side of the first directional valve (13) is connected to the working oil circuit of the first cylinder. The second directional valve (14) is connected to one side of the second directional valve (14) through the second main pump oil delivery circuit, and the other side of the second directional valve (14) is connected to the working oil circuit of the second cylinder. Alternatively, the synchronous lifting hydraulic system includes a main directional valve (10), the main oil pump (20) is connected to one side of the main directional valve (10) through the main pumping oil circuit, and the other side of the main directional valve (10) is connected in parallel to the working oil circuit of the first oil cylinder and the working oil circuit of the second oil cylinder.

6. The synchronous lifting hydraulic system according to any one of claims 2 to 5, characterized in that, The first cylinder (1) and the second cylinder (2), the first throttling element (5) and the second throttling element (6), the first hydraulic drive valve (7) and the second hydraulic drive valve (8) are all identical hydraulic devices.

7. The synchronous lifting hydraulic system according to claim 6, characterized in that, The first throttling element (5) is installed in the first cylinder rodless chamber oil passage (H11) of the first cylinder working oil passage, and the second throttling element (6) is installed in the second cylinder rodless chamber oil passage (H21) of the second cylinder working oil passage.

8. The synchronous lifting hydraulic system according to claim 1, characterized in that, One of the comparison ports of the first shuttle valve (11) is connected to the throttling front end of the first throttling element (5), and one of the comparison ports of the second shuttle valve (12) is connected to the throttling front end of the second throttling element (6).

9. The synchronous lifting hydraulic system according to claim 1, characterized in that, The hydraulic proportional valve (4) is a three-position three-way directional valve with an intermediate stop position.

10. The synchronous lifting hydraulic system according to claim 1, characterized in that, The drain oil passage (L1) is also provided with an auxiliary reversing valve (9), which is used to switch the first oil inlet passage and the second oil inlet passage to the first oil inlet (A) and the second oil inlet (B) of the hydraulic proportional valve (4).

11. A tower crane, characterized in that, The tower crane includes a synchronous lifting hydraulic system according to any one of claims 1 to 10, wherein the first cylinder (1) and the second cylinder (2) are the double lifting cylinders of the tower crane.

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