A variable amplitude hydraulic system and engineering equipment

Abstract

The present invention provides a variable-length hydraulic system and engineering equipment, and relates to the technical field of engineering machinery. The variable-length hydraulic system includes a variable-length oil cylinder, a balancing valve, a first reversing valve, a pressure reducing valve, a first non-return valve and a hydraulically controlled buffer valve; the rodless chamber, the balancing valve and the first reversing valve of the variable-length oil cylinder are connected in sequence through a first oil circuit, and the rod chamber of the variable-length oil cylinder is connected to the first reversing valve through a second oil circuit; the pressure reducing valve is connected in sequence to the control end of the first non-return valve and the balancing valve through a third oil circuit, and the conduction direction of the first non-return valve is the same as the oil supply direction of the third oil circuit; the two oil ports of the hydraulically controlled buffer valve are respectively connected to the second oil circuit and the third oil circuit, and the connection between the oil port of the hydraulically controlled buffer valve and the third oil circuit is located between the first non-return valve and the balancing valve, and the two control ends of the hydraulically controlled buffer valve are also respectively connected to the second oil circuit and the third oil circuit. The variable-length hydraulic system avoids the problem of boom shaking caused by instability of the balancing valve, thereby improving safety.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a variable amplitude hydraulic system and engineering equipment. Background Art

[0002] The boom arm's luffing action in engineering equipment is performed by a luffing cylinder. In the prior art, the luffing cylinder is generally controlled by a balancing valve. By controlling the balancing valve, the luffing cylinder is prevented from stalling when performing the boom arm's downward movement.

[0003] There are two types of boom control for the balancing valve, namely deadweight boom control and pressurized boom control. Deadweight boom control is generally used for large load conditions of medium and long booms. In this condition, the stable pilot pressure generated by an external oil source is used to control the opening and closing of the balancing valve, and the boom action is achieved by relying on the weight of the load. Pressurized boom control is generally used for small load conditions of short booms. In this condition, the circuit's own oil pressure is used to control the pilot opening of the balancing valve, and also controls the rod chamber of the boom cylinder.

[0004] When the pressurized variable amplitude control operates quickly, that is, when the reversing valve switches quickly, there is a step response in the rod chamber pressure of the cylinder, and the pressure in the rod chamber rises very quickly. This rise in starting pressure is generally completed in a very short time. Although this improves the system response, the pilot chamber of the balancing valve is controlled by the rod chamber pressure of the cylinder, which will make the balancing valve unstable and cause the boom to shake. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, the present application provides a boom-changing hydraulic system and engineering equipment to solve the technical problem in the prior art that when the pressurized boom-changing control is rapidly actuated, the pilot chamber of the balancing valve is controlled by the rod chamber pressure of the cylinder, causing the balancing valve to become unstable and causing the boom to shake.

[0006] To achieve the above-mentioned purpose, on the one hand, the present application provides a variable amplitude hydraulic system, including a variable amplitude cylinder, a balance valve, a first reversing valve, a pressure reducing valve, a first non-return valve and a hydraulically controlled buffer valve;

[0007] The rodless chamber of the luffing cylinder, the balancing valve and the first reversing valve are connected in sequence through a first oil circuit, and the rod chamber of the luffing cylinder is connected to the first reversing valve through a second oil circuit;

[0008] The pressure reducing valve is connected to the control end of the first one-way valve and the balance valve in sequence through the third oil circuit, and the conduction direction of the first one-way valve is the same as the oil supply direction of the third oil circuit;

[0009] The two oil ports of the hydraulically controlled buffer valve are connected to the second oil circuit and the third oil circuit respectively, and the connection between the oil port of the hydraulically controlled buffer valve and the third oil circuit is located between the first check valve and the balancing valve, and the two control ends of the hydraulically controlled buffer valve are also connected to the second oil circuit and the third oil circuit respectively;

[0010] In the initial state, the second oil circuit and the third oil circuit are cut off in the buffer valve. When the oil pressure in the second oil circuit gradually increases and is greater than the sum of the equivalent pressure behind the hydraulically controlled buffer valve and the spring force, the buffer valve gradually realizes the connection between the second oil circuit and the third oil circuit.

[0011] In a possible implementation, the hydraulically controlled buffer valve is a two-position two-way valve, and the hydraulically controlled buffer valve includes a cut-off position and an on position. The second oil circuit and the third oil circuit cooperate to control the switching of the cut-off position and the on position by oil pressure.

[0012] In a possible embodiment, a switch control component is also arranged between the third oil circuit and the control end of the hydraulically controlled buffer valve, and the switch control component includes a first damping hole and a second one-way valve arranged in parallel, wherein the conduction direction of the second one-way valve is the same as the oil supply direction of the third oil circuit.

[0013] In a possible implementation, the luffing hydraulic system further includes a flow regulating device and a pressure relief bypass;

[0014] The pressure relief bypass is connected to the third oil circuit and is located between the balance valve and the hydraulically controlled buffer valve;

[0015] The flow regulating device is arranged on the pressure relief bypass.

[0016] In a possible implementation manner, the flow regulating device includes a second damping hole and a flow control valve, and the second damping hole and the flow control valve are sequentially arranged along the pressure relief direction of the pressure relief bypass.

[0017] In a possible implementation manner, the flow control valve is a hydraulically controlled valve, and a control end of the flow control valve is connected to the third oil circuit and is close to a liquid inlet side of the first one-way valve.

[0018] In a possible implementation manner, the luffing hydraulic system further includes a third damping hole, and the third damping hole is arranged in the third oil circuit, and the third damping hole is close to the connection between the third oil circuit and the pressure relief bypass.

[0019] In a possible implementation manner, the first reversing valve is linked to the pressure reducing valve, and the first reversing valve controls the magnitude of the pressure reducing pressure output by the pressure reducing valve.

[0020] In a possible implementation manner, the luffing hydraulic system further includes a second reversing valve, a back pressure valve and an oil tank;

[0021] The second reversing valve is arranged in the second oil circuit, and the second reversing valve is located between the first reversing valve and the hydraulically controlled buffer valve;

[0022] The second reversing valve is also connected in sequence to the back pressure valve and the oil tank via a back pressure oil circuit.

[0023] On the other hand, the present application also provides an engineering equipment, including a boom and the above-mentioned boom-changing hydraulic system, wherein the boom-changing hydraulic system is used to control the boom to perform a boom-changing action.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention relates to a variable-length hydraulic system and engineering equipment provided in an application. The variable-length hydraulic system comprises a variable-length cylinder, a balancing valve, a first reversing valve, a pressure reducing valve, a first one-way valve and a hydraulically controlled buffer valve. The rodless chamber, the balancing valve and the first reversing valve of the variable-length cylinder are connected in sequence through a first oil circuit, and the rod chamber of the variable-length cylinder is connected to the first reversing valve through a second oil circuit. The pressure reducing valve is connected in sequence to the control ends of the first one-way valve and the balancing valve through a third oil circuit, and the conduction direction of the first one-way valve is the same as the oil supply direction of the third oil circuit. The two oil ports of the hydraulically controlled buffer valve are respectively connected to the second oil circuit and the third oil circuit, and the connection between the oil port of the hydraulically controlled buffer valve and the third oil circuit is located between the first one-way valve and the balancing valve, and the two control ends of the hydraulically controlled buffer valve are also respectively connected to the second oil circuit and the third oil circuit.

[0026] In the initial state of the variable amplitude hydraulic system provided by the present application, the second oil circuit and the third oil circuit are cut off in the buffer valve. When the pressurized variable amplitude control is performed, it is divided into three stages:

[0027] During the startup phase, the first reversing valve switches, and the pressure reducing valve outputs the pressure reducing pressure to act on the control end of the balancing valve through the third oil circuit, controlling the balancing valve to open to the first opening state. At the same time, the second oil circuit supplies oil to the rod chamber, and the rodless chamber returns oil to the first oil circuit.

[0028] In the transition stage, the oil pressure of the second oil circuit gradually increases to a certain pressure. At this time, when the oil pressure of the second oil circuit is greater than the sum of the equivalent pressure after the hydraulic control buffer valve and the spring force, the buffer valve gradually realizes the connection between the second oil circuit and the third oil circuit, and the oil pressure of the second oil circuit and the oil pressure of the third oil circuit reach equilibrium;

[0029] During the acceleration phase, the oil pressure in the second oil circuit continues to increase, and the first one-way valve is cut off. At this time, the oil pressure in the second oil circuit directly acts on the control end of the balancing valve, causing the balancing valve to open to the second opening state.

[0030] Therefore, even if the pressurized amplitude control operates quickly, that is, the first reversing valve switches quickly, the oil pressure in the second oil circuit will not directly act on the control end of the balancing valve, but will need to go through a smooth transition stage. Without affecting the system response, the balancing valve can smoothly transition from the first opening state to the second opening state, effectively avoiding the problem of boom shaking caused by instability of the balancing valve, and at the same time solving the problem of boom instability at startup, thereby improving the safety of equipment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 A schematic diagram of the structure of a first variable amplitude hydraulic system provided in an embodiment of the present application is shown;

[0033] Figure 2 Shows Figure 1 A local enlarged schematic diagram of the middle A;

[0034] Figure 3 A schematic diagram of the structure of a second variable amplitude hydraulic system provided in an embodiment of the present application is shown;

[0035] Figure 4 A schematic diagram of the structure of a third variable amplitude hydraulic system provided in an embodiment of the present application is shown.

[0036] Description of main component symbols:

[0037] 1-luffing cylinder; 2-balancing valve; 3-first reversing valve; 4-pressure reducing valve; 5-hydraulic control buffer valve; 6-first non-return valve; 7-switch control assembly; 8-oil tank; 9-flow regulating device; 10-third damping hole; 11-second reversing valve; 12-back pressure valve; 50-cut-off position; 51-conduction position; 70-first damping hole; 71-second non-return valve; 90-second damping hole; 91-flow control valve; 101-cylinder body; 102-piston rod; 103-rod chamber; 104-rodless chamber;

[0038] 100a - first oil circuit; 100b - second oil circuit; 100c - third oil circuit; 100d - pressure relief bypass; 100e - back pressure oil circuit. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0044] Embodiment 1

[0045] See also Figure 1 and Figure 2 The embodiment provides a boom hydraulic system that can be applied to engineering equipment. When the boom is rapidly moved under pressurized control, the boom will not shake, thereby improving the safety of equipment operation.

[0046] The luffing hydraulic system provided in this embodiment includes a luffing cylinder 1 , a balancing valve 2 , a first reversing valve 3 , a pressure reducing valve 4 , a first non-return valve 6 and a hydraulically controlled buffer valve 5 .

[0047] The luffing cylinder 1 is used to drive the boom of the engineering equipment (not shown) to perform a downward luffing movement, and the luffing cylinder 1 includes a cylinder body 101 and a piston rod 102 disposed in the cylinder body 101 and performing a piston movement relative to the cylinder body 101. It can be understood that the piston rod 102 divides the cylinder body 101 into a chamber with the piston rod 102 and a chamber without the piston rod 102, which are collectively referred to as the rodless chamber 104 and the rod chamber 103 below.

[0048] The rodless chamber 104 of the luffing cylinder 1 , the balancing valve 2 and the first reversing valve 3 are connected in sequence through the first oil circuit 100 a , and the rod chamber 103 of the luffing cylinder 1 is connected to the first reversing valve 3 through the second oil circuit 100 b .

[0049] It can be understood that when the first oil circuit 100a supplies oil, the rodless chamber 104 of the luffing cylinder 1 receives oil, the second oil circuit 100b returns oil, and the piston rod 102 of the luffing cylinder 1 extends. At this time, the luffing cylinder 1 drives the boom to perform the arm lifting movement; when the second oil circuit 100b supplies oil, the rod chamber 103 of the luffing cylinder 1 receives oil, the first oil circuit 100a returns oil, and the piston rod 102 of the luffing cylinder 1 contracts. At this time, the luffing cylinder 1 drives the boom to perform the downward movement.

[0050] Among them, the first reversing valve 3 is also connected to the first oil supply device (not shown) and the oil tank 8. The first reversing valve 3 is used to realize the switching between the oil supply and return of the first oil circuit 100a and the second oil circuit 100b. That is to say, by controlling the valve core action of the first reversing valve 3, the amplitude change action of the amplitude change cylinder 1 can be controlled.

[0051] It can be understood that only when the balancing valve 2 is opened, the first oil circuit 100a is connected with the rodless chamber 104 of the luffing oil cylinder 1, and the hydraulic oil in the rodless chamber 104 can smoothly enter the first oil circuit 100a, and then return to the oil tank 8 through the first reversing valve 3. Therefore, the luffing oil cylinder 1 can be kept in an extended state through the balancing valve 2, so that the boom can maintain the load. When the first oil circuit 100a flows into the rodless chamber 104 of the luffing oil cylinder 1, it is not controlled by the balancing valve 2, and the hydraulic oil of the first oil circuit 100a can directly enter the rodless chamber 104 of the luffing oil cylinder 1.

[0052] Furthermore, the first oil supply device includes a first oil pump, an oil suction end of the first oil pump is connected to the oil tank 8, and an oil supply end of the first oil pump is connected to the first reversing valve 3 through a pipeline.

[0053] The pressure reducing valve 4 is connected to the first check valve 6 and the control end of the balancing valve 2 in sequence through the third oil circuit 100c, and the conducting direction of the first check valve 6 is the same as the oil supply direction of the third oil circuit 100c, and the first check valve 6 is cut off in the reverse direction. In other words, the pressure reducing pressure output by the pressure reducing valve 4 directly acts on the control end of the balancing valve 2 through the third oil circuit 100c, providing a pilot pressure for the balancing valve 2 to control the movement of the valve core of the balancing valve 2, thereby controlling the opening state of the balancing valve 2.

[0054] The oil inlet end of the pressure reducing valve 4 is connected to a second oil supply device (not shown), which is used to deliver control oil to the pressure reducing valve 4. The control oil enters the third oil circuit 100c after being regulated by the pressure reducing valve 4, and then acts on the control end of the balancing valve 2.

[0055] Furthermore, the second oil supply device includes a second oil pump, the oil suction end of the second oil pump is connected to the oil tank 8, and the oil supply end of the second oil pump is connected to the pressure reducing valve 4 through a pipeline.

[0056] The two oil ports of the hydraulically controlled buffer valve 5 are respectively connected to the third oil circuit 100c and the second oil circuit 100b, and the connection between the oil port of the hydraulically controlled buffer valve 5 and the third oil circuit 100c is located between the first one-way valve 6 and the balancing valve 2. The two control ends of the hydraulically controlled buffer valve 5 are also respectively connected to the third oil circuit 100c and the second oil circuit 100b. The hydraulic oil in the third oil circuit 100c and the second oil circuit 100b controls the valve core movement of the hydraulically controlled buffer valve 5.

[0057] Please refer to Figure 2 Furthermore, the hydraulically controlled buffer valve 5 is a two-position two-way valve, and specifically can be a two-position two-way throttle valve.

[0058] The hydraulically controlled buffer valve 5 includes a cut-off position 50 and a conduction position 51. The second oil circuit 100b and the third oil circuit 100c cooperate to control the valve core movement of the hydraulically controlled buffer valve 5 through oil pressure, thereby realizing the switching of the cut-off position 50 and the conduction position 51 of the hydraulically controlled buffer valve 5.

[0059] It can be understood that in the initial state, the hydraulically controlled buffer valve 5 is in the cut-off position 50, and the second oil circuit 100b and the third oil circuit 100c are in the cut-off state in the hydraulically controlled buffer valve 5, that is, the second oil circuit 100b and the third oil circuit 100c are not connected. Similarly, when the hydraulically controlled buffer valve 5 is in the conducting position 51, the second oil circuit 100b and the third oil circuit 100c are connected to each other in the hydraulically controlled buffer valve 5. In other words, by pushing the valve core of the hydraulically controlled buffer valve 5 to move, the switching between the cut-off position 50 and the conducting position 51 of the hydraulically controlled buffer valve 5 can be achieved.

[0060] Please refer to Figure 1 and Figure 2 The variable amplitude hydraulic system provided in this embodiment is divided into three stages when performing pressurized variable amplitude control, as follows:

[0061] During the startup phase, the first reversing valve 3 switches, and the pressure reducing valve 4 outputs the pressure reducing pressure to act on the control end of the balancing valve 2 through the third oil circuit 100c, controlling the balancing valve 2 to open to the first opening state. At the same time, the second oil circuit 100b supplies oil to the rod chamber 103, and the rodless chamber 104 returns oil to the first oil circuit 100a.

[0062] It can be understood that when the first reversing valve 3 is switched, the first oil supply device is connected to the second oil circuit 100b through the first reversing valve 3, and the hydraulic oil is delivered to the rod chamber 103 of the variable-speed oil cylinder 1; the reduced pressure output by the pressure reducing valve 4 is transmitted to the control end of the balancing valve 2 through the oil pressure of the hydraulic oil in the third oil circuit 100c. In addition, in the startup phase, the control end of the balancing valve 2 is controlled by the external oil source input by the pressure reducing valve 4, and the hydraulic oil in the rodless chamber 104 can return to the oil tank 8 through the first oil circuit 100a and the first switching valve.

[0063] During the transition stage, the oil pressure in the second oil circuit 100b gradually increases to a certain pressure. At this time, when the oil pressure in the second oil circuit 100b is greater than the sum of the equivalent pressure after the hydraulic control buffer valve 5 and the spring force, the buffer valve gradually realizes the connection between the second oil circuit 100b and the third oil circuit 100c, and the oil pressure in the second oil circuit 100b and the oil pressure in the third oil circuit 100c reach a balance.

[0064] It can be understood that the equivalent pressure after the hydraulically controlled buffer valve 5 includes the oil pressure of the third oil circuit 100c, and in the transition stage, the hydraulic oil of the second oil circuit 100b and the third oil circuit 100c act together on the control end of the balancing valve 2, but the pilot pressure of the control end of the balancing valve 2 remains unchanged, that is, the valve core of the balancing valve 2 maintains its original position, and the balancing valve 2 still remains in the first opening state.

[0065] During the acceleration phase, the oil pressure in the second oil circuit 100b continues to increase, and the first one-way valve 6 is closed. At this time, the oil pressure in the second oil circuit 100b directly acts on the control end of the balancing valve 2, so that the balancing valve 2 opens to the second opening state.

[0066] It can be understood that when the oil pressure of the second oil circuit 100b continues to increase, the hydraulic oil of the second oil circuit 100b enters the third oil circuit 100c, and at the same time, the oil pressure of the second oil circuit 100b is greater than the oil pressure of the third oil circuit 100c, so the hydraulic oil entering the second oil circuit 100b tends to move toward the pressure reducing valve 4, and at this time the first check valve 6 is reversely cut off. That is to say, when the first check valve 6 is cut off, the oil pressure of the second oil circuit 100b directly acts on the control end of the balance valve 2, and the second oil circuit 100b is connected to the rod chamber 103, so the pilot pressure of the control end of the balance valve 2 is consistent with the pressure of the rod chamber 103, thereby realizing a smooth transition from external oil source control to internal oil source control.

[0067] Therefore, even when the pressurized variable amplitude control is in rapid action, that is, the first reversing valve 3 is switched rapidly, the oil pressure of the second oil circuit 100b will not directly act on the control end of the balancing valve 2, but needs to go through a gentle transition stage. Therefore, without affecting the system response, the balancing valve 2 can smoothly transition from the first opening state to the second opening state, effectively avoiding the problem of boom shaking caused by the instability of the balancing valve 2, and solving the problem of the boom being unstable at startup, thereby improving the safety of the equipment.

[0068] In addition, through the smooth transition characteristics of the hydraulically controlled buffer valve 5, the opening of the balancing valve 2 smoothly transitions from the first opening state to the second opening state, and the flow rate in the first opening state of the balancing valve 2 is smaller than the flow rate in the second opening state, thereby achieving a smooth transition of the variable-length cylinder 1 from slow and stable operation to fast and stable operation to meet the needs of rapid action, thereby improving operating efficiency.

[0069] Among them, it can be understood that due to the strong throttling and buffering effect when the hydraulic control buffer valve 5 switches from the cut-off position 50 to the conduction position 51, when the oil pressure of the second oil circuit 100b acts on the control end of the balance valve 2, no large pressure fluctuation will occur, thereby ensuring the smoothness of the transition, realizing a smooth transition of the variable-length oil cylinder 1 from slow and stable operation to fast and stable operation, and improving operation safety.

[0070] In some embodiments, the balancing valve 2 adopts a full-flow limiting balancing valve 2, so that the valve core transition position of the balancing valve 2 is smoother, and the pressure will not drop suddenly at the moment of opening, thereby improving stability and safety.

[0071] Therefore, the oil pressure of the second oil circuit 100b is stable and controllable, and the flow limiting effect of the balance valve 2 makes the amplitude change action more stable when the pressurized amplitude change control is performed, and stalling will not occur, thereby improving the safety of the operation. Therefore, the amplitude change hydraulic system provided by this embodiment still retains the anti-stall function of the balance valve 2. When the oil pressure of the rod chamber 103 of the amplitude change oil cylinder 1 drops suddenly, that is, the oil pressure of the second oil circuit 100b drops suddenly, the hydraulic control buffer valve 5 can be quickly reset to the initial state, so that the pilot pressure at the control end of the balance valve 2 is reduced, and the opening of the balance valve 2 is also reduced accordingly, so as to obtain the deceleration effect of the amplitude change action, and play a certain anti-stall effect.

[0072] Please refer to Figure 1 and Figure 2 In some embodiments, a switch control component 7 is further provided between the third oil circuit 100c and the control end of the hydraulically controlled buffer valve 5. The switch control component 7 includes a first damping hole 70 and a second one-way valve 71 arranged in parallel, wherein the conduction direction of the second one-way valve 71 is the same as the oil supply direction of the third oil circuit 100c.

[0073] It can be understood that, through the cooperation of the first damping hole 70 and the second one-way valve 71, the slow opening and fast closing of the hydraulically controlled buffer valve 5 is achieved, thereby reducing the sudden pressure change after the hydraulically controlled buffer valve 5 and ensuring a smoother adjustment of the balancing valve 2.

[0074] In other embodiments, it is understandable that a pressure relief bypass 100d is further provided between the balancing valve 2 and the hydraulically controlled buffer valve 5, and the pressure relief bypass 100d is connected to the third oil circuit 100c, that is, the connection between the pressure relief bypass 100d and the third oil circuit 100c is located between the balancing valve 2 and the hydraulically controlled buffer valve 5. The other end of the pressure relief bypass 100d is connected to the oil tank 8 to achieve pressure relief of the third oil circuit 100c. In other words, the pressure relief bypass 100d is used to achieve pressure relief between the balancing valve 2 and the hydraulically controlled buffer valve 5. Thus, after the amplitude variation action stops, the balancing valve 2 can be closed.

[0075] The pressure relief bypass 100d is also provided with a second damping hole 90, which can play the role of throttling, pressure regulation, buffering and vibration prevention for the pressure relief bypass 100d. After the amplitude variation action stops, the balancing valve 2 is slowly closed to achieve the effect of stopping buffering.

[0076] Embodiment 2

[0077] See also Figure 1 and Figure 3 The embodiment provides a variable amplitude hydraulic system, which can be applied to engineering equipment. When the pressurized variable amplitude control is in rapid motion, the boom will not shake, thereby improving the safety of equipment operation. This embodiment is an improvement made on the basis of the above embodiment 1. Compared with the above embodiment 1, the difference is that:

[0078] Please refer to Figure 3 In this embodiment, the variable amplitude hydraulic system further includes a flow regulating device 9 and a pressure relief bypass 100d. The pressure relief bypass 100d is connected to the third oil circuit 100c, and the connection between the pressure relief bypass 100d and the third oil circuit 100c is located between the balance valve 2 and the hydraulic control buffer valve 5, and the other end of the pressure relief bypass 100d is connected to the oil tank 8.

[0079] The flow regulating device 9 is disposed on the pressure relief bypass 100d. That is to say, part of the hydraulic oil in the third oil circuit 100c can return to the oil tank 8 through the flow regulating device 9 on the pressure relief bypass 100d.

[0080] It can be understood that the flow regulating device 9 can adjust the flow of hydraulic oil flowing through the pressure relief bypass 100d, thereby achieving the effect of dividing the oil pressure of the hydraulic oil in the third oil circuit 100c, and this pressure division effect is mainly reflected in the startup stage of executing the pressurized amplitude control.

[0081] Please refer to Figure 1 and Figure 3 In the boom-changing hydraulic system provided in the present embodiment, during the start-up phase of the pressurized boom-changing control: the first reversing valve 3 is switched, and the first oil supply device is connected with the second oil circuit 100b through the first reversing valve 3 to deliver the hydraulic oil to the rod chamber 103 of the boom-changing cylinder 1; the reduced pressure output by the pressure reducing valve 4 is transmitted to the control end of the balancing valve 2 through the hydraulic oil of the third oil circuit 100c; when the balancing valve 2 is opened, the hydraulic oil in the rodless chamber 104 of the boom-changing cylinder 1 passes through the first oil circuit 100a, the balancing valve 2 and the first reversing valve 3 and returns to the oil tank 8, thereby realizing the pressurized boom-changing action, that is, the boom-changing cylinder 1 drives the boom to perform the downward movement.

[0082] Among them, the flow regulating device 9 on the pressure relief bypass 100d divides the oil pressure transmitted to the control end of the balancing valve 2. Through the pressure dividing effect of the flow regulating device 9, the control end of the balancing valve 2 obtains a more stable pilot pressure at the moment of starting the variable amplitude movement, so that the balancing valve 2 opens more smoothly, thereby effectively avoiding the problem of the boom shaking downward at the moment of starting the balancing valve 2, and the impact problem, thereby improving the safety of equipment operation.

[0083] Further, the flow regulating device 9 includes a second damping hole 90 and a flow control valve 91, which are sequentially arranged along the pressure relief direction of the pressure relief bypass 100d. It can be understood that the pressure relief direction of the pressure relief bypass 100d is the flow direction of the hydraulic oil along the pressure relief bypass 100d to the oil tank 8.

[0084] In this embodiment, the purpose of providing the second damping hole 90 and the flow regulating device 9 is to throttle, regulate pressure, buffer and prevent vibration on the pressure relief bypass 100d, thereby adjusting the oil pressure of the third oil circuit 100c, avoiding oil pressure fluctuations in the third oil circuit 100c, and making the oil pressure in the third oil circuit 100c more stable.

[0085] Furthermore, the flow control valve 91 is a hydraulically controlled valve, and the control end of the flow control valve 91 is connected to the third oil circuit 100c, that is, the movement of the valve core of the flow control valve 91 is controlled by the oil pressure of the hydraulic oil in the third oil circuit 100c, thereby controlling the adjustment of the opening size of the flow control valve 91. Specifically, the connection between the control end of the flow control valve 91 and the third oil circuit 100c is located between the first check valve 6 and the pressure reducing valve 4, and close to the liquid inlet side of the first check valve 6.

[0086] In this embodiment, if Figure 1 As shown, the flow control valve 91 is a two-position two-way valve, in which one cavity position is open and the other cavity position is open but has a throttling effect, and the throttling effect can make the cavity position have a large resistance or be cut off.

[0087] It can be understood that in the startup stage of the pressurized amplitude control, the reduced pressure output by the pressure reducing valve 4 is a process that gradually increases from small to large and then stabilizes. When the reduced pressure output by the pressure reducing valve 4 reaches the maximum, the valve core of the balancing valve 2 is controlled to move to a predetermined position, thereby controlling the opening of the balancing valve 2 to reach the first opening state.

[0088] And when the reduced pressure output by the pressure reducing valve 4 gradually rises to the maximum, the oil pressure of the third oil circuit 100c acting on the control end of the flow control valve 91 also gradually rises to the maximum. At this time, the valve core of the flow control valve 91 moves, so that the regulating pressure of the flow control valve 91 reaches the maximum. In other words, the resistance encountered by the hydraulic oil in the pressure relief bypass 100d gradually increases, so as to ensure that the reduced pressure gradually acts on the control end of the balancing valve 2, so that the pilot pressure acting on the control end of the balancing valve 2 gradually reaches the maximum, and the balancing valve 2 is ensured to open smoothly.

[0089] In other embodiments, the flow control valve 91 is a throttle valve or a relief valve, and the resistance adjustment of the pressure relief bypass 100d is controlled by the throttle valve or the relief valve.

[0090] The variable-length hydraulic system provided in this embodiment further includes a third damping hole 10, which is arranged in the third oil circuit 100c and is close to the connection between the third oil circuit 100c and the pressure relief bypass 100d. That is to say, the hydraulic oil in the third oil circuit 100c first passes through the third damping hole 10 for throttling, pressure regulation, buffering and vibration prevention, and then enters the pressure relief bypass 100d and the control end of the balance valve 2 respectively. Furthermore, when the variable-length action is started, the oil pressure in the third oil circuit 100c is buffered by the third damping hole 10, reducing the impact on the control end of the balance valve 2, and combined with the pressure-dividing effect of the second damping hole 90 on the pressure relief bypass 100d, the oil pressure acting on the control end of the balance valve 2 is more stable, and the balance valve 2 is opened more stably, thereby effectively avoiding the problem of the boom pitching shaking and the impact at the start moment, thereby improving the safety of the equipment operation.

[0091] Further, it can be understood that when the reduced pressure output by the pressure reducing valve 4 reaches a maximum, the regulating pressure of the flow control valve 91 also reaches a maximum or approaches a cut-off state, and the pressure-dividing effect of the pressure relief bypass 100d is weakened and restricted, so that the pilot pressure acting on the control end of the balancing valve 2 tends to the reduced pressure output by the pressure reducing valve 4. At this time, the pilot ratio of the balancing valve 2 equivalent to the circuit increases, the opening of the balancing valve 2 is maximum, and the piston rod 102 of the variable-length oil cylinder 1 runs faster, which makes the variable-length speed not affected by the oil temperature, thereby effectively avoiding the oil pressure generated by the fixed second damping hole 90 and the third damping hole 10 being affected by the temperature, reducing the power consumption of the system and improving the working efficiency.

[0092] Embodiment 3

[0093] See also Figures 1 to 4 The embodiment provides a variable amplitude hydraulic system, which can be applied to engineering equipment. When the pressurized variable amplitude control is in rapid motion, the boom will not shake, thereby improving the safety of equipment operation. This embodiment is an improvement made on the basis of the above-mentioned embodiment 1 or embodiment 2. Compared with the above-mentioned embodiment 1 or embodiment 2, the difference is that:

[0094] In this embodiment, the first reversing valve 3 can be a three-position four-way electromagnetic or manual reversing valve. The three-position four-way first reversing valve 3 includes four oil ports, two of which are respectively connected to the first oil circuit 100a and the second oil circuit 100b, and the other two oil ports are respectively connected to the first oil supply device and the oil tank 8.

[0095] Please refer to Figure 1 , wherein, when the first reversing valve 3 is in the left position, at this time, the valve core of the first reversing valve 3 is close to the control end of the pressure reducing valve 4, and the first oil circuit 100a is connected to the oil tank 8, and the second oil circuit 100b is connected to the first oil supply device.

[0096] When the first reversing valve 3 is in the right position, the valve core of the first reversing valve 3 is away from the control end of the pressure reducing valve 4 , and the first oil circuit 100 a is connected to the first oil supply device, and the second oil circuit 100 b is connected to the oil tank 8 .

[0097] When the first reversing valve 3 is in the middle position, that is, the first reversing valve 3 is in the reset state, the first oil circuit 100a is connected with the oil tank 8, and the second oil circuit 100b is cut off. At the same time, a throttling structure is arranged in the oil passage connecting the first oil circuit 100a with the oil tank 8, so that the hydraulic oil in the first oil circuit 100a has a stronger throttling effect when returning to the oil tank 8. The throttling effect can provide a higher back pressure effect when the boom action is started, so as to avoid stalling when the boom cylinder 1 drives the boom to pitch downward.

[0098] Furthermore, the first reversing valve 3 is linked with the pressure reducing valve 4 , and the first reversing valve 3 controls the magnitude of the reduced pressure output by the pressure reducing valve 4 .

[0099] Specifically, the valve core of the first reversing valve 3 is connected to the control of the pressure reducing valve 4 , and the opening of the pressure reducing valve 4 is controlled by moving the valve core of the first reversing valve 3 , thereby achieving control of the reduced pressure output by the pressure reducing valve 4 .

[0100] The principle of the linkage between the first reversing valve 3 and the pressure reducing valve 4 is:

[0101] When the valve core of the first reversing valve 3 moves toward the control end close to the pressure reducing valve 4, the pressure reducing pressure output by the pressure reducing valve 4 gradually increases, and the first reversing valve 3 is functionally located in the left position; when the valve core of the first reversing valve 3 moves away from the control end of the pressure reducing valve 4, the pressure reducing pressure output by the pressure reducing valve 4 gradually decreases or is closed.

[0102] That is to say, by controlling the distance between the valve core of the first reversing valve 3 and the control end of the pressure reducing valve 4, the contraction speed of the piston rod 102 of the variable amplitude oil cylinder 1 can be controlled. At the same time, the movement of the first reversing valve 3 and the pressure reducing valve 4 is synchronized, thereby improving the reliability of system operation.

[0103] In some embodiments, a position sensor can also be used to detect the valve core position of the first reversing valve 3, and feedback the position information of the valve core of the first reversing valve 3, and then connect the control end of the pressure reducing valve 4 through the actuator, so as to realize the control of the pressure reducing pressure output by the pressure reducing valve 4, and also realize the linkage between the first reversing valve 3 and the pressure reducing valve 4.

[0104] In other embodiments, the actuator may be an electric element or a hydraulic element.

[0105] Embodiment 4

[0106] See also Figures 1 to 4The embodiment provides a variable amplitude hydraulic system, which can be applied to engineering equipment. When the pressurized variable amplitude control is in rapid motion, the boom will not shake, thereby improving the safety of equipment operation. This embodiment is an improvement made on the basis of any one of the above embodiments 2 to 3. Compared with any one of the above embodiments, the difference is that:

[0107] Please refer to Figure 4 In this embodiment, the luffing hydraulic system further includes a second reversing valve 11 and a back pressure valve 12. The second reversing valve 11 is disposed in the second oil circuit 100b, the second reversing valve 11 is located between the first reversing valve 3 and the luffing oil cylinder 1, and the second reversing valve 11 is also connected to the back pressure valve 12 and the oil tank 8 in sequence through the back pressure oil circuit 100e.

[0108] Furthermore, the back pressure valve 12 is a one-way valve with reverse cutoff; the second reversing valve 11 is a two-position three-way electromagnetic reversing valve. In this embodiment, the second reversing valve 11 can realize flexible switching between the deadweight variable amplitude control and the pressurized variable amplitude control of the variable amplitude hydraulic system.

[0109] It can be understood that the pressurized boom control is that the second oil circuit 100b delivers hydraulic oil of a certain pressure to the rod chamber 103 of the boom cylinder 1 to drive the piston rod 102 of the boom cylinder 1 to retract; the deadweight boom control is that the piston rod 102 of the boom cylinder 1 is driven to retract simply by the weight of the boom and the load on the boom.

[0110] Please refer to Figure 3 and Figure 4 , wherein, in this embodiment, the self-weight luffing and pressurized luffing action principles of the luffing hydraulic system are:

[0111] During automatic luffing control, the first reversing valve 3 is switched to the left position, and the first oil supply device delivers hydraulic oil to the second oil circuit 100b; at the same time, the second reversing valve 11 is energized, the left position is open, and the hydraulic oil in the second oil circuit 100b is divided into two routes through the second reversing valve 11. The first route flows to the hydraulic control buffer valve 5 and the rod chamber 103 of the luffing cylinder 1; the second route is to return to the oil tank 8 through the back pressure oil circuit 100e.

[0112] It can be understood that since the back pressure oil circuit 100e has basically no resistance, the hydraulic oil in the second oil circuit 100b mainly returns to the oil tank 8 along the second route. Therefore, when the piston rod 102 of the boom cylinder 1 contracts under the drive of gravity, the rod chamber 103 of the boom cylinder 1 sucks oil into the second oil circuit 100b. The setting of the back pressure valve 12 can prevent the rod chamber 103 of the boom cylinder 1 from being sucked into the oil tank 8.

[0113] In the process of automatic amplitude variation control, the hydraulically controlled buffer valve 5 is always in the cut-off position 50, and the stable opening of the balance valve 2 is stably controlled by the oil pressure of the pressure reducing valve 4 through the third oil circuit 100c.

[0114] The automatic amplitude control process can achieve small flow micro-amplitude movement, improve the movement accuracy, make full use of the deadweight of the boom and load, and minimize power consumption. When the equipment boom load is large, deadweight amplitude control can be used to improve stability.

[0115] During pressurized amplitude control, the first reversing valve 3 is switched so that the first reversing valve 3 is located in the left position function, and the first oil supply device delivers hydraulic oil to the second oil circuit 100b; at the same time, the second reversing valve 11 is in a power-off state, that is, it is located in the initial position, and the hydraulic oil in the second oil circuit 100b flows along the first line to the hydraulic control buffer valve 5 and the rod chamber 103 of the amplitude cylinder 1 respectively, and the second line is in the cut-off state in the second reversing valve 11.

[0116] It can be understood that at the moment when the first reversing valve 3 is switched on, the oil pressure in the second oil circuit 100b is lower than the sum of the equivalent pressure behind the hydraulically controlled buffer valve 5 and the spring force, and the start-up phase is entered; when the oil pressure in the second oil circuit 100b gradually increases, the oil pressure in the second oil circuit 100b is greater than the sum of the equivalent pressure behind the hydraulically controlled buffer valve 5 and the spring force, and the transition phase is entered; when the oil pressure in the second oil circuit 100b increases again to the point where the first one-way valve 6 is cut off, the acceleration phase is entered.

[0117] Among them, due to the buffering effect of the first damping hole 70 in the switch control component 7, the switching of the hydraulically controlled buffer valve 5 is smoother, and the pilot control of the balancing valve 2 obtains a gentle pressure gain, so that the amplitude change action realizes a smooth transition from slow to fast action, and the action will not stall due to the stable pilot pressure, and the amplitude change is stable and efficient.

[0118] Furthermore, in the acceleration stage, the oil pressure in the second oil circuit 100b increases, and the pilot pressure of the balancing valve 2 also gradually increases, and is greater than the reduced pressure output by the reducing valve 4. The first one-way valve 6 is in a cut-off state. At this time, the pilot pressure control of the balancing valve 2 is transformed from the external oil source of the third oil circuit 100c to the internal oil source control of the second oil circuit 100b. The oil pressure in the second oil circuit 100b is consistent with the oil pressure in the rod chamber 103 of the boom cylinder 1. At the same time, the flow control valve 91 reaches the maximum flow limit and the resistance is also the largest, thereby realizing rapid action of the boom cylinder 1.

[0119] The pressurized variable amplitude control process can achieve small flow micro-variable amplitude action, improve the action accuracy, and also have efficient and fast variable amplitude action mode, making the control more flexible. When the equipment arm load is small, pressurized variable amplitude control can be used to improve work efficiency.

[0120] Compared with the prior art, the variable amplitude hydraulic system provided in this embodiment has the following advantages:

[0121] 1. Through the pressure-dividing effect of the flow regulating device 9, the balance valve 2 is opened more smoothly, which solves the problem of shaking and impact when the boom is driven downward by the variable-luffing cylinder 1, and increases the stability of starting and stopping;

[0122] 2. Use the hydraulically controlled buffer valve 5 to ensure a smooth transition of the pilot pressure acting on the control end of the balancing valve 2, thus ensuring that the balancing valve 2 opens smoothly;

[0123] 3. Through the cooperation of hydraulic components such as the second reversing valve 11 and the hydraulically controlled balancing valve 2, the flexible switching of deadweight amplitude change and pressurized amplitude change is realized, and at the same time, the combination of external control and internal control of the pilot pressure is realized to achieve stable opening and slow operation with large load and stable opening and fast operation with small load, meet the requirements of different working conditions, reduce energy consumption and improve working efficiency;

[0124] 4. Realize the equivalent variable pilot ratio control of the balancing valve 2, solve the influence of oil temperature on the running speed, and minimize energy consumption;

[0125] 5. The full-flow limiting balancing valve 2 is adopted, and the transition position of the valve core is smoother, and the pressure will not drop suddenly at the moment of opening, which improves stability and safety;

[0126] 6. While ensuring stability, the system response is effectively improved.

[0127] Embodiment 5

[0128] See also Figures 1 to 4 The present embodiment provides an engineering equipment, including a boom and a boom-length hydraulic system provided by any one of the above-mentioned embodiments 1 to 5.

[0129] The variable-length hydraulic system is used to control the boom to perform variable-length actions, effectively avoiding the boom's pitching and shaking, and the impact problem at the moment of starting, thereby improving the safety of equipment operation. At the same time, it also has the advantages of the variable-length hydraulic system provided by any one of the above-mentioned embodiments 1 to 5.

[0130] In some embodiments, the engineering equipment may be a crane, a gantry crane, or a rock drilling device.

[0131] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0132] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A variable amplitude hydraulic system, characterized in that: It includes a variable-luff cylinder, a balancing valve, a first reversing valve, a pressure reducing valve, a first non-return valve and a hydraulically controlled buffer valve; The rodless chamber of the luffing cylinder, the balancing valve and the first reversing valve are connected in sequence through a first oil circuit, and the rod chamber of the luffing cylinder is connected to the first reversing valve through a second oil circuit; The pressure reducing valve is connected to the control end of the first one-way valve and the balance valve in sequence through the third oil circuit, and the conduction direction of the first one-way valve is the same as the oil supply direction of the third oil circuit; The two oil ports of the hydraulically controlled buffer valve are respectively connected to the second oil circuit and the third oil circuit, and the connection between the oil port of the hydraulically controlled buffer valve and the third oil circuit is located between the first one-way valve and the balancing valve, and the two control ends of the hydraulically controlled buffer valve are also respectively connected to the second oil circuit and the third oil circuit; the hydraulically controlled buffer valve includes a cut-off position and a conduction position, and the second oil circuit and the third oil circuit cooperate to control the switching of the cut-off position and the conduction position through oil pressure; In the initial state, the second oil circuit and the third oil circuit are cut off in the hydraulically controlled buffer valve. When the oil pressure in the second oil circuit gradually increases and is greater than the sum of the equivalent pressure behind the hydraulically controlled buffer valve and the spring force, the hydraulically controlled buffer valve gradually realizes the connection between the second oil circuit and the third oil circuit. The oil inlet end of the pressure reducing valve is connected to a second oil supply device, which is used to deliver control oil to the pressure reducing valve. The first reversing valve is linked to the pressure reducing valve, and the first reversing valve controls the size of the reduced pressure output by the pressure reducing valve.

2. The variable amplitude hydraulic system according to claim 1, characterized in that: The hydraulically controlled buffer valve is a two-position two-way valve.

3. The variable amplitude hydraulic system according to claim 1, characterized in that: A switch control assembly is also provided between the third oil circuit and the control end of the hydraulically controlled buffer valve, and the switch control assembly includes a first damping hole and a second one-way valve arranged in parallel, wherein the conduction direction of the second one-way valve is the same as the oil supply direction of the third oil circuit.

4. The variable amplitude hydraulic system according to claim 1, characterized in that: The variable amplitude hydraulic system also includes a flow regulating device and a pressure relief bypass; The pressure relief bypass is connected to the third oil circuit and is located between the balance valve and the hydraulically controlled buffer valve; The flow regulating device is arranged on the pressure relief bypass.

5. The variable amplitude hydraulic system according to claim 4, characterized in that: The flow regulating device comprises a second damping hole and a flow control valve, and the second damping hole and the flow control valve are arranged in sequence along the pressure relief direction of the pressure relief bypass.

6. The luffing hydraulic system according to claim 5, characterized in that: The flow control valve is a liquid-controlled valve, and a control end of the flow control valve is connected to the third oil circuit and is close to the liquid inlet side of the first one-way valve.

7. The luffing hydraulic system according to claim 4, characterized in that: The luffing hydraulic system further includes a third damping hole, which is arranged in the third oil circuit and is close to a connection between the third oil circuit and the pressure relief bypass.

8. The luffing hydraulic system according to any one of claims 1 to 7, characterized in that: The variable amplitude hydraulic system also includes a second reversing valve, a back pressure valve and an oil tank; The second reversing valve is arranged in the second oil circuit, and the second reversing valve is located between the first reversing valve and the hydraulically controlled buffer valve; The second reversing valve is also connected in sequence to the back pressure valve and the oil tank via a back pressure oil circuit.

9. An engineering equipment, characterized in that: It comprises a boom and a boom-changing hydraulic system as claimed in any one of claims 1 to 8, wherein the boom-changing hydraulic system is used to control the boom to perform a boom-changing action.

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