Negative load balance hydraulic circuit, power system and crane

Abstract

The invention belongs to the technical field of cranes, and particularly relates to a negative load balance hydraulic circuit, a power system and a crane, and the negative load balance hydraulic circuit comprises a balance hydraulic pump which is connected with a transfer case or a power take-off port of an engine or is connected with an execution hydraulic pump on the transfer case in series; the pressure control valve group is communicated between the oil outlet of the balance hydraulic pump and the oil return path, and the pressure control valve group is used for controlling the hydraulic oil pressure of the oil outlet of the balance hydraulic pump; and the control unit is used for sending a control signal to the pressure control valve group under the condition that the power system of the crane has a negative load so as to adjust the hydraulic oil pressure of the oil outlet of the balance hydraulic pump and further control the balance moment of the balance hydraulic pump, so that the balance moment is matched with the negative load moment. By adopting the negative load balancing hydraulic circuit, the negative load in a power system can be balanced, so that the operation efficiency of the crane under the working condition of the negative load is improved on the premise of safe operation.

Description

Technical Field

[0001] This invention belongs to the field of crane technology, specifically relating to a negative load balancing hydraulic circuit, a power system, a crane, a power control method, and a parameter matching method for the negative load balancing hydraulic circuit. Background Technology

[0002] Cranes, as heavy lifting equipment commonly used in the construction industry, primarily function to transfer heavy objects to different spatial positions through the luffing and slewing movements of the boom. For hydraulically driven cranes, the power transmission system typically employs three independent hydraulic closed-loop drives, providing power to the hoisting mechanism, luffing mechanism, and slewing mechanism respectively: the mechanical energy output from the engine is distributed through a transfer case, driving the corresponding hydraulic pumps of the three mechanisms to rotate. Under positive load conditions (such as lifting, luffing, and slewing of the boom), the engine outputs power to the actuators through the hydraulic system to complete the lifting or reduction of the load's amplitude. The power transmission path is clear, and the operating state is stable.

[0003] However, during actual construction, crane power systems inevitably face negative load conditions. Typical scenarios include outward boom extension (when the load swings outward with the boom, gravity generates a downward pull) and downward movement of the hoisted load (the load's own weight drives the hoisting ropes to lower). Under these conditions, the gravitational potential energy of the load is converted into mechanical energy and input back into the hydraulic system. This causes the hydraulic pump to change from a "power output component" to a "power input component," transmitting reverse torque (i.e., negative power input) to the engine through the transfer case. When the movement speed under negative load conditions is high (such as rapid lowering of the load or rapid outward swing of a heavy load), the negative torque input to the engine will increase significantly. If this negative torque exceeds the sum of the engine's own auxiliary torque (such as accessory drive torque) and internal friction torque, the engine will lose its own power control, be dragged and accelerated by the reverse torque, and experience a runaway "speed" phenomenon, seriously threatening equipment safety and the lives of construction personnel.

[0004] To address the risk of engine stall under heavy load conditions, existing technologies commonly employ limiting the input of negative power. This is achieved through hydraulic system flow control and mechanical limits to reduce the downward speed of the load and the outward luffing speed under heavy load, thereby reducing the negative torque input to the engine and preventing speed runaway. However, this approach has significant drawbacks. For instance, during the near-completion phase of high-rise building construction (such as when dismantling climbing formwork, scaffolding, and other auxiliary facilities), cranes frequently operate in lifting and lowering modes. In such cases, speed limitations prolong the time required for each lowering operation, significantly reducing work efficiency. This efficiency loss is particularly pronounced in scenarios involving the large-scale dismantling of auxiliary facilities. Summary of the Invention

[0005] The purpose of this invention is to provide a negative load balancing hydraulic circuit, a power system, a crane, a power control method, and a parameter matching method for the negative load balancing hydraulic circuit, so as to balance the negative load of the power system and improve the operating efficiency of the crane under negative load conditions while ensuring safe operation.

[0006] To achieve the above objectives, the present invention provides a negative load balancing hydraulic circuit, which is applied to a crane. The negative load balancing hydraulic circuit includes: A balance hydraulic pump is connected to the power take-off port of the transfer case or engine, or connected in series with the actuator hydraulic pump on the transfer case. The pressure control valve assembly is connected between the outlet and return oil circuit of the balance hydraulic pump. The pressure control valve assembly is used to control the hydraulic oil pressure at the outlet of the balance hydraulic pump. When the crane's power system is under negative load, the control unit sends a control signal to the pressure control valve assembly to adjust the hydraulic oil pressure at the outlet of the balance hydraulic pump, thereby controlling the balancing torque of the balance hydraulic pump so that the balancing torque matches the negative load torque.

[0007] In some embodiments, the pressure control valve assembly includes: a pressure control valve having a pressure inlet and a pressure outlet, the pressure inlet being connected to the outlet of a balanced hydraulic pump, the pressure outlet being connected to a return oil circuit, and the pressure control valve being used to control the pressure difference between the pressure inlet and the pressure outlet as the conduction pressure.

[0008] In some embodiments, the pressure control valve includes a cartridge pressure valve and a pilot control assembly. The cartridge pressure valve has a pressure control port, a pressure inlet port, and a pressure outlet port. The pilot control assembly is connected to the pressure control port of the cartridge pressure valve and is used to control the magnitude of the conduction pressure according to a control signal sent by the control unit.

[0009] In some embodiments, the pilot control component includes: a connecting branch, the first end of which is connected to the outlet of the balance hydraulic pump; a pilot branch, which is connected between the second end of the connecting branch and the return oil circuit; an overflow component, which is disposed on the pilot branch and electrically connected to the control unit; and a first damper, which is disposed on the connecting branch and the pressure control port is connected to the connecting branch between the first damper and the pilot branch.

[0010] In some implementations, the number of pilot branches is one or multiple branches arranged in parallel, and each pilot branch is equipped with an overflow component.

[0011] In some embodiments, the overflow assembly includes: a first electrically controlled switching valve and an overflow valve connected in series, wherein the overflow pressure of the overflow valve on each pilot branch is different; or, the overflow assembly includes a first electrically controlled overflow valve.

[0012] In some embodiments, the pilot control assembly further includes a second electrically controlled switching valve connected in parallel with the pilot branch, wherein the control terminal of the second electrically controlled switching valve is electrically connected to the control unit.

[0013] In some implementations, the negative load balancing hydraulic circuit further includes a safety relief valve connected between the outlet of the balancing hydraulic pump and the return oil circuit.

[0014] In some implementations, the negative load balancing hydraulic circuit further includes a pressure sensing element for detecting the hydraulic oil pressure at the outlet of the balancing hydraulic pump.

[0015] A second aspect of the present invention provides a power system comprising: the aforementioned negative load balancing hydraulic circuit; an engine; a transfer case, driven and connected to the engine, the transfer case having multiple power take-off ports; and multiple actuator hydraulic pumps, each driven and connected to one of the multiple power take-off ports on the transfer case.

[0016] A third aspect of the present invention provides a crane including the power system described above.

[0017] A fourth aspect of the present invention provides a power control method applied to the aforementioned power system. The power control method includes the following steps: determining the negative load value of the power system when there is a negative load; determining the control parameters of the input pressure control valve group based on the negative load value of the power system; and controlling the pressure control valve group to start and adjust the hydraulic oil pressure at the outlet of the balancing hydraulic pump to balance the negative load of the power system.

[0018] In some embodiments, the power system includes multiple actuating hydraulic circuits, each of which includes an actuating hydraulic pump. The power control method further includes the following steps: acquiring the torque of the multiple actuating hydraulic pumps in the power system; determining the transfer case required torque based on the torque of the multiple actuating hydraulic pumps and the transfer case speed ratio; determining the total required torque of the engine based on the transfer case required torque, the engine's internal friction torque, and the engine's auxiliary device torque; and determining that the power system has a negative load when the total required torque is less than zero.

[0019] In some implementations, the step of determining the negative load value of the power system when there is a negative load in the power system includes: determining the total demand torque as the negative load value of the power system when the total demand torque is less than zero; and determining that the power system has no negative load when the total demand torque is greater than or equal to zero.

[0020] In some implementations, the step of determining the control parameters of the input pressure control valve group based on the negative load value of the power system includes: determining the balance load of the negative load balancing hydraulic circuit based on the negative load value; determining the hydraulic oil pressure adjustment value at the outlet of the balance hydraulic pump based on the balance load value; and determining the control parameters based on the hydraulic oil pressure adjustment value.

[0021] The fifth aspect of the present invention provides a power control method applied to the aforementioned power system. The power control method includes the following steps: when the engine output torque is greater than zero or the fuel consumption rate is greater than a first preset value A, controlling the outlet of the balance hydraulic pump to maintain a minimum hydraulic oil pressure; when the engine output torque is less than or equal to zero and the fuel consumption rate is less than a second preset value B, gradually increasing the hydraulic oil pressure at the outlet of the balance hydraulic pump; until the fuel consumption rate is greater than a third preset value C, controlling the hydraulic oil pressure in the negative load balance hydraulic circuit to no longer increase, wherein A > C > B.

[0022] The sixth aspect of the present invention provides a parameter matching method for a negative load balancing hydraulic circuit, applied to the aforementioned power system. The parameter matching method includes: obtaining the maximum negative torque corresponding to the maximum negative load in the power system; determining the maximum working pressure in the negative load balancing hydraulic circuit based on the maximum negative torque; determining the displacement range of the balancing hydraulic pump based on the maximum working pressure; and determining the working pressure range of the pressure control valve group based on the displacement range of the balancing hydraulic pump and the maximum working pressure.

[0023] In the above technical solution, the negative load balancing hydraulic circuit is applied to a crane. This circuit includes a balancing hydraulic pump, a pressure control valve assembly, and a control unit. The balancing hydraulic pump is connected to the power take-off port of the transfer case or engine, or connected in series with the actuator hydraulic pump on the transfer case. The pressure control valve assembly is connected between the outlet and return oil lines of the balancing hydraulic pump, used to precisely regulate the hydraulic oil pressure at the pump's outlet. When the crane's power system is under negative load, the control unit can send a control signal to the pressure control valve assembly to dynamically adjust the hydraulic oil pressure at the pump's outlet, thereby controlling the balancing torque of the pump to match the negative load torque. By employing this negative load balancing hydraulic circuit, when a negative load exists in the power system, the pressure control valve assembly can be controlled to adjust the hydraulic oil pressure at the pump's outlet to control the pump's balancing torque, thus balancing the negative load on the power system. This effectively prevents the engine from losing speed control due to excessive negative torque, ensuring equipment safety and the safety of construction personnel. Furthermore, the design of this negative load balancing hydraulic circuit eliminates the need for the power system to limit the scale of negative power input to ensure safety, thereby significantly improving work efficiency while ensuring safe operation.

[0024] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. Those skilled in the art can obtain other drawings based on the structures shown in these drawings without any inventive effort. In the drawings: Figure 1 A hydraulic schematic diagram of a negative load balancing hydraulic circuit provided according to the first embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a crane provided according to an embodiment of the present invention; Figure 3 This is a block diagram of the power transmission relationship of a power system according to an embodiment of the present invention; Figure 4 Hydraulic schematic diagram of the negative load balancing hydraulic circuit provided according to the second embodiment of the present invention Figure 5 A hydraulic schematic diagram of a negative load balancing hydraulic circuit provided according to a third embodiment of the present invention; Figure 6 A hydraulic schematic diagram of a negative load balancing hydraulic circuit provided according to the fourth embodiment of the present invention; Figure 7 A flowchart of a first power control method provided according to an embodiment of the present invention; Figure 8 A flowchart of a second power control method provided according to an embodiment of the present invention; Figure 9 A flowchart of a parameter matching method provided according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures 10 Balanced hydraulic pumps 21 Cartridge pressure valve 30 Pilot Control Components 22 Second electrically controlled relief valve 311 First Electrically Controlled Switch Valve 312 Overflow valve 313 First electrically controlled relief valve 32 First Damping 33 Second electrically controlled switching valve 34 Second Damping 40 Safety relief valve 50 Pressure testing components L1 connection branch L2 pilot branch L3 return oil circuit Detailed Implementation 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.

[0027] The following description, with reference to the accompanying drawings, describes the negative load balancing hydraulic circuit, power system, crane, power control method, and parameter matching method of the negative load balancing hydraulic circuit according to the present invention.

[0028] like Figure 1 The diagram shown is a hydraulic schematic of a negative load balancing hydraulic circuit provided according to the first embodiment of the present invention; as shown Figure 2 The diagram shown is a structural schematic of a crane provided according to an embodiment of the present invention; as follows: Figure 3 The diagram shown is a power transmission relationship block diagram of a power system provided according to an embodiment of the present invention. The negative load balancing hydraulic circuit provided in this embodiment of the present invention is applied to a crane. The negative load balancing hydraulic circuit includes: The balance hydraulic pump 10 is connected to the power take-off port of the transfer case or engine, or connected in series with the actuator hydraulic pump on the transfer case; The pressure control valve assembly is connected between the oil outlet of the balance hydraulic pump 10 and the return oil circuit L3. The pressure control valve assembly is used to control the hydraulic oil pressure at the oil outlet of the balance hydraulic pump 10. The control unit (not shown in the figure) sends a control signal to the pressure control valve group when the power system of the crane is under negative load, so as to adjust the hydraulic oil pressure at the outlet of the balance hydraulic pump 10, and then control the balancing torque of the balance hydraulic pump 10 so that the balancing torque matches the negative load torque.

[0029] In existing technologies, crane power systems often experience negative loads. These negative loads can cause the hydraulic pump to switch from a power output component to a power input component, transmitting reverse torque to the engine through the transfer case. When the negative load is significant, the engine may lose its own power control, being dragged and accelerated by the reverse torque, resulting in runaway speed. Therefore, cranes often limit the engine's speed and power when the power system is under negative load to prevent accidents. However, limiting power or speed significantly reduces operational efficiency, hindering the economic viability of crane operations. The hydraulic pumps used in cranes include hoisting pump sets, luffing pump sets, slewing pump sets, and other auxiliary pump sets, which are used to drive the hoisting mechanism, luffing mechanism, slewing mechanism, and auxiliary mechanisms, respectively.

[0030] This invention provides a negative load balancing hydraulic circuit, which includes a balancing hydraulic pump 10, a pressure control valve assembly, and a control unit. The balancing hydraulic pump 10 can be connected to the power take-off port of a transfer case or engine, or connected in series with the actuator hydraulic pump on the transfer case. The pressure control valve assembly is connected between the outlet of the balancing hydraulic pump 10 and the return oil circuit L3, and its function is to precisely control the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10. When the crane power system experiences a negative load condition, such as when the boom tilts inward to generate a downward pulling force on the load, or when the lifting load moves downward, the gravitational potential energy of the load is converted into mechanical energy and input back into the hydraulic system. At this time, the pressure control valve assembly adjusts the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 according to the instructions of the control unit, thereby controlling the balancing torque of the balancing hydraulic pump 10 to match the negative load torque. Upon detecting a negative load on the power system, the control unit quickly sends a control signal to the pressure control valve assembly. Based on the magnitude of the negative load and operating conditions, it adjusts the hydraulic oil pressure in the negative load balancing hydraulic circuit, ensuring the balancing hydraulic pump 10 has a certain positive load. This counteracts part or all of the reverse input negative torque, preventing the engine from losing speed control due to excessive negative torque. This process does not require reducing the engine's speed or power, thus not affecting the crane's normal operating efficiency. In one embodiment, the crane using the negative load balancing hydraulic circuit can be a tower crane, crawler crane, truck crane, etc.

[0031] In one embodiment, such as Figure 1 As shown, the pressure control valve assembly includes a pressure control valve with a pressure inlet and a pressure outlet. The pressure inlet is connected to the outlet of the balance hydraulic pump 10, and the pressure outlet is connected to the return oil circuit L3. The pressure control valve controls the pressure difference between the pressure inlet and the pressure outlet to be the conduction pressure. The pressure inlet is connected to the outlet of the balance hydraulic pump 10, allowing hydraulic oil to flow from the balance hydraulic pump 10 into the pressure control valve. The pressure outlet is connected to the return oil circuit L3, through which hydraulic oil flows to the return oil circuit L3. The key function of the pressure control valve is to control the pressure difference between the pressure inlet and the pressure outlet to be the conduction pressure, thereby adjusting the pressure at the outlet of the balance hydraulic pump 10. The conduction pressure can be set according to actual needs, for example, by taking a large value to prevent excessive load; or it can be set to a value adjustable according to the control signal, allowing adjustment of the positive load based on the magnitude of the negative load.

[0032] In one embodiment, such as Figure 1As shown, the pressure control valve includes a cartridge pressure valve 21 and a pilot control assembly. The cartridge pressure valve 21 has a pressure control port, a pressure inlet port, and a pressure outlet port. The pilot control assembly 30 is connected to the pressure control port of the cartridge pressure valve 21 and is used to control the magnitude of the conduction pressure according to the control signal sent by the control unit. The cartridge pressure valve 21 is a hydraulic control element with a special structure. Its cartridge installation method makes it flexible in hydraulic systems. The cartridge pressure valve 21 typically has a pressure inlet port, a pressure outlet port, and a pressure control port. The pilot control assembly 30 can adjust the conduction pressure through the pressure control port. For example, if the pilot control assembly sets the conduction pressure to 10 bar, the pressure difference between the pressure inlet port and the pressure outlet port will rise to 10 bar, and the pressure difference between the pressure inlet port and the pressure outlet port of the cartridge pressure valve 21 will be maintained. In addition, the cartridge pressure valve 21 also has the characteristic of large flow rate, making it suitable for high-flow-rate applications. The pilot control component 30 can receive electrical signals from the control unit and precisely regulate the conduction pressure based on these signals. In practical applications, when a negative load occurs in the power system, the control unit quickly analyzes the negative load situation and sends a corresponding control signal to the pilot control component 30. Upon receiving the signal, the pilot control component 30 immediately operates the pressure control port of the cartridge pressure valve 21, thereby changing the conduction pressure. This allows the pressure control valve assembly to dynamically and precisely adjust the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 according to the specific conditions of the negative load. This precise control method ensures that the negative load balance hydraulic circuit functions quickly and effectively when a negative load occurs, preventing the engine from experiencing speed loss due to excessive negative torque and ensuring the stable operation of the crane's power system.

[0033] In one embodiment, such as Figure 1As shown, the pilot control assembly 30 includes: a connecting branch L1, a pilot branch L2, an overflow assembly, and a first damper 32. The first end of the connecting branch L1 is connected to the outlet of the balance hydraulic pump 10. The pilot branch L2 connects the second end of the connecting branch L1 to the return oil circuit L3. The overflow assembly is located on the pilot branch L2 and is electrically connected to the control unit. The first damper 32 is located on the connecting branch L1, and the pressure control port is connected to the connecting branch L1 between the first damper 32 and the pilot branch L2. The connecting branch L1 serves as the connection channel between the pilot control assembly 30 and the outlet of the balance hydraulic pump 10, and its function is to introduce the hydraulic oil output by the balance hydraulic pump 10 into the pilot branch L2. The pilot branch L2 then guides a portion of the hydraulic oil in the connecting branch L1 to the return oil circuit L3. Together with the connecting branch L1, they form a hydraulic oil circulation loop. An overflow assembly is installed on the pilot branch L2 and electrically connected to the control unit. It precisely controls the hydraulic oil flow pressure in the pilot branch L2 based on electrical signals sent by the control unit. When the hydraulic oil pressure in the pilot branch L2 reaches the pressure value set by the overflow assembly, the overflow assembly opens, allowing excess hydraulic oil to flow through to the return oil circuit L3, thus achieving precise control of the hydraulic oil pressure in the pilot branch L2. A first damper 32 is installed on the connecting branch L1. Its function is to generate a pressure difference. When the pilot branch L2 is open, the pressure difference across the first damper 32 causes the valve core of the cartridge pressure valve 21 to move, making the pressure at the inlet of the cartridge pressure valve 21 greater than the pressure at the control port. This movement of the valve core of the cartridge pressure valve 21 then connects the pressure inlet and outlet ports. Using the aforementioned pilot control assembly 30 structure, the flow pressure of the cartridge pressure valve 21 can be precisely and quickly adjusted according to the instructions of the control unit. This allows the pressure control valve assembly to dynamically and precisely adjust the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 according to the actual load of the crane's power system. In a specific embodiment, the pilot control component 30 includes a second damper 34, which is disposed on the oil line between the pressure control port and the connecting branch L1. The second damper 34 is used to reduce pressure fluctuations at the pressure control port.

[0034] In one embodiment, such as Figure 4The diagram shown is a hydraulic schematic of a load balancing hydraulic circuit according to a second embodiment of the present invention. The number of pilot branches L2 can be one or multiple branches connected in parallel, and each pilot branch L2 is equipped with an overflow component. When there are multiple pilot branches L2, one pilot branch L2 can be selected to be activated, and the overflow pressure of the overflow component of that pilot branch L2 becomes the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10. Using the above hydraulic structure, the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 can be flexibly adjusted according to different working conditions. Specifically, when the crane is in different operating states, the size and nature of the load may vary. If there is only one pilot branch L2, its adjustment capability is relatively limited when facing complex and variable load conditions. However, by setting multiple pilot branches L2 in parallel, and each pilot branch L2 is equipped with an overflow component, more adjustment options are provided for the system.

[0035] In one embodiment, such as Figure 4 As shown, the overflow assembly includes: a first electrically controlled switching valve 311 and an overflow valve 312 connected in series, with different overflow pressures on each pilot branch L2; or as shown... Figure 5 As shown, the overflow assembly includes a first electrically controlled overflow valve 313. When the overflow assembly includes a first electrically controlled switching valve 311 and an overflow valve 312 with a fixed overflow pressure, the number of pilot branches L2 can be set to multiple, with each overflow valve 312 on the pilot branch L2 having a different overflow pressure setting value. When the control unit issues a command according to the size of the load, the corresponding first electrically controlled switching valve 311 opens, causing the overflow valve 312 with the corresponding overflow pressure to work, thereby precisely controlling the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10. This design can provide more detailed and precise pressure regulation for loads of different sizes and characteristics, ensuring that the load balancing hydraulic circuit can function effectively under various working conditions. When the overflow assembly uses the first electrically controlled overflow valve 313, its advantage lies in its simplified structure. A single electrically controlled element can dynamically adjust the overflow pressure, thereby quickly and accurately changing the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 according to the control unit's instructions. This method is highly practical and convenient for handling heavy load conditions requiring rapid response. Regardless of the overflow assembly structure used, the heavy load balance hydraulic circuit can flexibly and accurately adjust the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 according to the actual load of the crane's power system, effectively ensuring the stable operation of the power system.

[0036] In one embodiment, such as Figure 4 or Figure 5The diagram shows the hydraulic principle of a negative load balancing hydraulic circuit according to a third embodiment of the present invention. The pilot control assembly 30 further includes a second electrically controlled switch valve 33, connected in parallel with the pilot branch L2, and the control terminal of the second electrically controlled switch valve 33 is electrically connected to the control unit. The second electrically controlled switch valve 33 is connected in parallel with the pilot branch L2. When the second electrically controlled switch valve 33 is open, the hydraulic oil in the connecting branch L1 can also flow into the return oil circuit L3. A pressure difference exists between the pressure control port and the pressure inlet port of the cartridge pressure valve 21, and the pressure inlet and pressure outlet ports of the cartridge pressure valve 21 are connected. The hydraulic oil in the negative load balancing hydraulic circuit circulates in the circuit at a lower pressure, resulting in a lower positive load. When the second electrically controlled switch valve 33 is open, the pilot branch L2 functions normally, precisely adjusting the conduction pressure of the cartridge pressure valve 21 according to the instructions of the control unit. At this time, if a negative load occurs in the crane power system, the pressure control valve assembly will quickly adjust the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 according to the control signal from the control unit. Specifically, under negative load conditions, the control unit analyzes the magnitude and nature of the negative load and sends corresponding commands to the pilot control component 30. Using the aforementioned pilot control component 30 can prevent the engine from losing speed control due to excessive negative torque, ensuring the stable operation of the crane's power system, while also eliminating the need to reduce engine speed or power, thus not affecting the crane's normal operating efficiency.

[0037] In one embodiment, such as Figure 6 The diagram shown is a hydraulic schematic of a negative load balancing hydraulic circuit according to a fourth embodiment of the present invention. The pressure control valve group includes a second electrically controlled relief valve 22 and a second electrically controlled switch valve 33 connected in parallel with the second electrically controlled switch valve 33. When the second electrically controlled switch valve 33 is open, the outlet of the balancing hydraulic pump 10 operates at a lower pressure, resulting in a lower positive load fed back to the engine. When the second electrically controlled switch valve 33 is closed, the control unit controls the opening pressure of the second electrically controlled relief valve 22 as needed to adjust the outlet pressure of the balancing hydraulic pump 10, thereby adjusting the positive load fed back to the engine as required. The flow rate of the second electrically controlled relief valve 22 is typically lower than that of the cartridge pressure valve 21; therefore, this embodiment is applied to cranes with lower flow rates. If the crane's flow rate exceeds a certain range, using the cartridge pressure valve 21 can more appropriately meet the needs of the hydraulic system, ensuring that the negative load balancing hydraulic circuit can still operate stably and efficiently under higher flow conditions.

[0038] In one embodiment, the negative load balancing hydraulic circuit further includes a safety relief valve 40, connected between the outlet of the balancing hydraulic pump 10 and the return oil circuit L3. The relief pressure of the safety relief valve 40 is set according to the pressure-bearing capacity of the hydraulic components in the negative load balancing hydraulic circuit. Its function is to automatically open and connect the outlet of the balancing hydraulic pump 10 and the return oil circuit L3 when the hydraulic oil pressure in the negative load balancing hydraulic circuit exceeds a safety threshold, allowing excess hydraulic oil to flow to the return oil circuit L3, thereby preventing damage to the hydraulic components due to excessive pressure. In practical applications, when the crane power system experiences abnormal operating conditions, such as a sudden large external force impact or a malfunction in the control unit causing the pressure control valve group to malfunction, the hydraulic oil pressure in the negative load balancing hydraulic circuit may rise sharply. At this time, the safety relief valve 40 can promptly release the excessive pressure, ensuring the safe and stable operation of the negative load balancing hydraulic circuit.

[0039] In one embodiment, the negative load balancing hydraulic circuit further includes a pressure detection element 50 for detecting the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10. The pressure detection element 50 can detect the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 in real time. When the pressure detection element 50 detects pressure data, it converts it into an electrical signal and transmits it to the control unit. After receiving this pressure data, the control unit quickly analyzes and processes it to determine whether the outlet pressure of the balancing hydraulic pump 10 is appropriate and makes targeted adjustments.

[0040] In one embodiment, such as Figure 3 As shown, a power system is provided, including: the aforementioned negative load balancing hydraulic circuit, an engine, a transfer case, and multiple actuator hydraulic pumps. The transfer case is driven and connected to the engine, and has multiple power take-off ports. The multiple actuator hydraulic pumps are driven and connected to the multiple power take-off ports on the transfer case one-to-one. Specifically, the multiple actuator hydraulic pumps are a rotary pump group, a luffing pump group, a hoisting pump group, and an auxiliary pump group. The aforementioned multiple actuator hydraulic pumps are driven and connected to the multiple power take-off ports on the transfer case one-to-one. The balancing hydraulic pump of the negative load balancing hydraulic circuit can be driven and connected to the power take-off ports on the transfer case or the engine, or it can be connected in series with one of the actuator hydraulic pumps to output a balancing torque that matches the negative load torque.

[0041] In one embodiment, a crane is provided, including the power system described above.

[0042] In one embodiment, such as Figure 7 The diagram shown is a flowchart of a first power control method according to an embodiment of the present invention. The power control method is applied to the aforementioned power system and includes the following steps: S101. Determine the negative load value of the power system when there is a negative load on the power system.

[0043] S102. Determine the control parameters of the input pressure control valve group based on the negative load value of the power system.

[0044] S103. The control pressure control valve group starts and adjusts the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 to balance the negative load of the power system.

[0045] In S101, determining the negative load value of the power system is the crucial initial step in the entire power control method. This requires comprehensive calculation and analysis using a preset algorithm model based on the operating parameters of multiple hydraulic pumps, such as flow rate and pressure, combined with the current operating status of the crane, such as the angle of the boom, the weight of the load, and the direction of movement, to accurately determine the negative load value of the power system. In S102, the control parameters of the input pressure control valve group are determined based on the negative load value of the power system. Once the negative load value is determined, the control of the pressure control valve group can be determined according to the magnitude of the negative load value to adjust the outlet pressure of the balancing hydraulic pump 10 accordingly. In S103, the control unit controls the pressure control valve group to start and adjust the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 to balance the negative load of the power system. The control unit sends the determined control parameters to each component in the pressure control valve group in the form of electrical signals, such as the electrically controlled switching valve in the pilot control assembly 30 and the electrically controlled relief valve in the relief assembly. After receiving the electrical signals, these components quickly act according to the instructions. For example, the electrically controlled switching valve opens or closes according to a signal, changing the flow path of the hydraulic oil; the electrically controlled relief valve adjusts the relief pressure according to a signal, thereby changing the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10. Through the dynamic adjustment of the pressure control valve group, the balancing hydraulic pump 10 generates a certain positive load, the magnitude and direction of which match the negative load of the power system, thereby achieving effective balancing of the negative load.

[0046] In one embodiment, the power system includes multiple actuating hydraulic circuits, each including an actuating hydraulic pump. The power control method further includes the following steps: acquiring the torque of the multiple actuating hydraulic pumps in the power system; determining the required torque of the transfer case based on the torque of the multiple actuating hydraulic pumps and the transfer case speed ratio; determining the total required torque of the engine based on the required torque of the transfer case, the internal friction torque of the engine, and the auxiliary torque of the engine; and determining that the power system has a negative load when the total required torque is less than zero. In a specific embodiment, the actuating hydraulic circuit may include a slewing hydraulic circuit, a hoisting hydraulic circuit, a luffing hydraulic circuit, an auxiliary hydraulic circuit, etc., and its torque data can be accurately acquired based on parameters such as the speed and displacement of the actuating hydraulic pumps in the actuating hydraulic circuit. After acquiring the torque of the multiple actuating hydraulic pumps, calculations are performed in conjunction with the transfer case speed ratio. The transfer case speed ratio is a fixed parameter that allows the torque of each actuating hydraulic pump to be converted to the input end of the transfer case, thereby determining the required torque of the transfer case. After determining the required torque of the transfer case, the internal friction torque of the engine and the auxiliary torque of the engine also need to be considered. The engine's power is also transmitted to auxiliary devices such as cooling fans and generators. These auxiliary devices also consume torque during operation, so this needs to be taken into account to accurately determine the engine's total torque demand. When the total torque demand is less than zero, it indicates that the power system is under a negative load. This accurate method of determining the negative load of the power system provides a precise basis for subsequently adjusting the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 to balance the negative load.

[0047] In one embodiment, the step of determining the negative load value of the power system when a negative load exists includes: determining the total demand torque as the negative load value when it is less than zero; and determining that the power system has no negative load when the total demand torque is greater than or equal to zero. When the total demand torque is less than zero, it indicates that the load direction of the power system is opposite to the load direction during normal operation. Determining the total demand torque as the negative load value in this case accurately reflects the negative load situation faced by the power system. When the total demand torque is greater than or equal to zero, it indicates that the power system is under normal load or positive load, and there is no negative load. Determining that the power system has no negative load in this case avoids unnecessary pressure adjustment operations and improves the operating efficiency of the power system. This clear and accurate method of determining the negative load value provides a reliable basis for the precise adjustment of the subsequent pressure control valve group, ensuring stable operation of the power system under various operating conditions.

[0048] In one specific embodiment, the presence of a negative load on the engine is determined according to the following formula (1): (1) in, For the total required torque, The sum of the input torques of multiple hydraulic pumps, where i is the speed ratio between the transfer case and the engine. This refers to the internal friction torque of the engine. The torque for other auxiliary devices connected to the engine. When When the value is less than zero, the power system has a negative load; otherwise, the power system does not have a negative load.

[0049] In one embodiment, the step of determining the control parameters of the input pressure control valve group based on the negative load value of the power system includes: determining the balancing load of the negative load balancing hydraulic circuit based on the negative load value; determining the hydraulic oil pressure adjustment value of the negative load balancing hydraulic circuit based on the balancing load value; and determining the control parameters based on the hydraulic oil pressure adjustment value. After determining the negative load value, the load that the negative load balancing hydraulic circuit needs to balance must first be determined based on this value. This is because different negative load values ​​mean different abnormal load conditions faced by the power system, and the load that needs to be balanced will also be different. After determining the balancing load value, the hydraulic oil pressure adjustment value of the outlet of the balancing hydraulic pump 10 is further determined based on it. The hydraulic oil pressure adjustment value is closely related to the balancing load value; only by accurately determining this adjustment value can the subsequent adjustment of the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 be guaranteed to be accurate and effective. Finally, the specific control parameters of the input pressure control valve group are determined based on the calculated hydraulic oil pressure adjustment value. These control parameters will directly guide the various components in the pressure control valve group, such as the electrically controlled switching valve in the pilot control assembly 30 and the electrically controlled relief valve in the relief assembly, to perform corresponding actions, thereby achieving precise adjustment of the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 to balance the load of the power system.

[0050] In one specific embodiment, the adjustment value of the hydraulic oil pressure is calculated according to the following formula (2): (2) in, To balance the hydraulic oil pressure adjustment value at the outlet of hydraulic pump 10, Let be the total required torque, and i be the speed ratio between the transfer case and the engine. For mechanical and hydraulic efficiency, To balance the displacement of hydraulic pump 10.

[0051] In one embodiment, such as Figure 8 The diagram shown is a flowchart of a second power control method provided according to an embodiment of the present invention. The power control method is applied to the aforementioned power system and includes the following steps: S201. When the engine output torque is greater than zero or the fuel consumption rate is greater than the first preset value A, the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 is controlled to maintain the minimum hydraulic oil pressure.

[0052] S202. When the engine output torque is less than or equal to zero and the fuel consumption rate is less than the second preset value B, gradually increase the hydraulic oil pressure at the outlet of the balance hydraulic pump 10.

[0053] S203. Until the fuel consumption rate is greater than the third preset value C, the hydraulic oil pressure in the control negative load balance hydraulic circuit will no longer increase, where A > C > B.

[0054] When the engine's output torque is greater than zero or the fuel consumption rate is greater than the first preset value A, it indicates a positive load in the power system. Under this condition, there is no need to balance the negative load through the negative load balancing hydraulic circuit; therefore, the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 can be controlled to maintain a minimum operating pressure. When the engine's output torque is less than zero, it indicates that the engine is under negative load, and the power system faces an abnormal load situation. A fuel consumption rate less than the second preset value B indicates that the engine's fuel consumption is at a relatively low level. In this case, gradually increasing the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 is to balance the negative load of the power system by adjusting the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10, allowing the engine to operate more stably. As the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 gradually increases, the engine's load condition will improve, and its fuel consumption rate will change accordingly. When the fuel consumption rate increases to a value greater than the third preset value C, it indicates that the power system is already under a certain positive load. Further increasing the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 may lead to excessive fuel consumption. Therefore, the hydraulic oil pressure in the negative load balance hydraulic circuit is controlled to no longer increase, maintaining the power system under relatively economical and stable operating conditions. This method of dynamically adjusting the hydraulic oil pressure at the outlet of the balance hydraulic pump 10 based on engine output torque and fuel consumption rate effectively improves the operating efficiency and stability of the power system, reduces energy consumption, and enhances the overall performance of the crane. The fuel consumption rate refers to the ratio of the amount of fuel consumed by the engine per unit time to the engine's output power.

[0055] In one embodiment, such as Figure 9 The diagram shows a flowchart of a parameter matching method provided according to an embodiment of the present invention. A parameter matching method for a negative load balancing hydraulic circuit is provided, applied to the aforementioned power system. The parameter matching method includes: S301, Obtain the maximum negative torque corresponding to the maximum negative load in the power system.

[0056] S302. Determine the maximum working pressure in the negative load balancing hydraulic circuit based on the maximum negative torque.

[0057] S303. Determine the displacement range of the balanced hydraulic pump 10 based on the maximum working pressure and the maximum negative torque.

[0058] S304. Determine the working pressure range of the pressure control valve assembly based on the displacement range and maximum working pressure of the balanced hydraulic pump 10.

[0059] When designing parameters for the negative load balancing hydraulic circuit, it is necessary to consider the maximum negative torque in the power system and determine the maximum working pressure in the negative load balancing hydraulic circuit based on the maximum negative torque. This is because, during the operation of the power system, the maximum negative torque represents the most extreme abnormal load condition that the power system may face. Only by ensuring that the negative load balancing hydraulic circuit can withstand such a maximum working pressure can the negative load be effectively balanced under various operating conditions. After determining the maximum working pressure, the displacement range of the balancing hydraulic pump 10 is determined based on this pressure value. The displacement of the balancing hydraulic pump 10 directly affects its ability to output hydraulic oil, while the maximum working pressure imposes limitations on the displacement range. Only by reasonably determining the displacement range can the balancing hydraulic pump 10 be guaranteed to operate normally at the maximum working pressure and meet the power system's demand for hydraulic oil flow. Next, based on the displacement range of the balancing hydraulic pump 10 and the maximum working pressure, the working pressure range of the pressure control valve assembly is further determined. The pressure control valve assembly is a key component in the load balancing hydraulic circuit. Its working pressure range needs to match the displacement and working pressure of the balancing hydraulic pump 10 to ensure precise adjustment of the hydraulic oil pressure at the outlet of the balancing hydraulic pump 10 under various working conditions, thereby achieving effective balancing of the load on the power system. This parameter matching method ensures that the design and selection of each component in the load balancing hydraulic circuit are more rational and scientific, improving the adaptability and reliability of the load balancing hydraulic circuit in the power system, and ultimately enhancing the performance and safety of the entire crane.

[0060] In one specific embodiment, the displacement range of the balanced hydraulic pump 10 is determined according to the following formula (3): (3) in, To balance the displacement of hydraulic pump 10, To balance the mechanical-hydraulic efficiency of hydraulic pump 10, This represents the maximum negative torque corresponding to the maximum negative load. This is the maximum working pressure in the negative load balancing hydraulic circuit.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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 negative load balancing hydraulic circuit, characterized in that, The negative load balancing hydraulic circuit is used in a crane, and the negative load balancing hydraulic circuit includes: A balance hydraulic pump (10) is connected to the power take-off port of the transfer case or engine, or connected in series with the actuator hydraulic pump on the transfer case; The pressure control valve assembly is connected between the oil outlet of the balanced hydraulic pump (10) and the return oil circuit (L3). The pressure control valve assembly is used to control the hydraulic oil pressure at the oil outlet of the balanced hydraulic pump (10). The control unit, when the power system of the crane is under negative load, sends a control signal to the pressure control valve group to adjust the hydraulic oil pressure at the outlet of the balance hydraulic pump (10), thereby controlling the balance torque of the balance hydraulic pump (10) so that the balance torque matches the negative load torque.

2. The negative load balancing hydraulic circuit according to claim 1, characterized in that, The pressure control valve assembly includes: The pressure control valve has a pressure inlet and a pressure outlet. The pressure inlet is connected to the outlet of the balanced hydraulic pump (10), and the pressure outlet is connected to the return oil circuit (L3). The pressure control valve is used to control the pressure difference between the pressure inlet and the pressure outlet to be the conduction pressure.

3. The negative load balancing hydraulic circuit according to claim 2, characterized in that, The pressure control valve includes a cartridge pressure valve (21) and a pilot control assembly. The cartridge pressure valve (21) has a pressure control port, a pressure inlet port and a pressure outlet port. The pilot control assembly (30) is connected to the pressure control port of the cartridge pressure valve (21) and is used to control the magnitude of the conduction pressure according to the control signal sent by the control unit.

4. The negative load balancing hydraulic circuit according to claim 3, characterized in that, The pilot control component (30) includes: The first end of the connecting branch (L1) is connected to the oil outlet of the balanced hydraulic pump (10); The pilot branch (L2) is connected between the second end of the connecting branch (L1) and the return oil circuit (L3); An overflow assembly is provided on the pilot branch (L2), and the overflow assembly is electrically connected to the control unit; The first damper (32) is provided on the connecting branch (L1), and the pressure control port is connected to the connecting branch (L1) between the first damper (32) and the pilot branch (L2).

5. The negative load balancing hydraulic circuit according to claim 4, characterized in that, The number of pilot branches (L2) is one or multiple branches arranged in parallel, and each pilot branch (L2) is provided with an overflow component.

6. The negative load balancing hydraulic circuit according to claim 5, characterized in that, The overflow component includes: The first electrically controlled switching valve (311) and the relief valve (312) are connected in series, and the relief pressure of the relief valve (312) on each of the pilot branches (L2) is different; or, The overflow assembly includes a first electrically controlled overflow valve (313).

7. The negative load balancing hydraulic circuit according to any one of claims 4 to 6, characterized in that, The pilot control component (30) also includes: The second electrically controlled switch valve (33) is connected in parallel with the pilot branch (L2), and the control terminal of the second electrically controlled switch valve (33) is electrically connected to the control unit.

8. The negative load balancing hydraulic circuit according to any one of claims 1 to 6, characterized in that, The negative load balancing hydraulic circuit also includes: A safety relief valve (40) is connected between the outlet of the balanced hydraulic pump (10) and the return oil circuit (L3).

9. The negative load balancing hydraulic circuit according to any one of claims 1 to 6, characterized in that, The negative load balancing hydraulic circuit also includes: Pressure detection element (50) is used to detect the hydraulic oil pressure at the outlet of the balanced hydraulic pump (10).

10. A power system, characterized in that, include: The negative load balancing hydraulic circuit according to any one of claims 1 to 9; engine; The transfer case is connected to the engine drive, and the transfer case is provided with multiple power take-off ports; Multiple hydraulic pumps are driven and connected to multiple power take-off ports on the transfer case, one by one.

11. A crane, characterized in that, Includes the power system as described in claim 10.

12. A power control method, characterized in that, Applied to the power system of claim 10, the power control method includes the following steps: When the power system is under negative load, determine the negative load value of the power system; The control parameters for inputting the pressure control valve group are determined based on the negative load value of the power system. The pressure control valve group is activated and the hydraulic oil pressure at the outlet of the balance hydraulic pump (10) is adjusted to balance the negative load of the power system.

13. The power control method according to claim 12, characterized in that, The power system includes multiple hydraulic circuits, each of which includes an hydraulic pump. The power control method further includes the following steps: Obtain the torque of multiple hydraulic pumps in the power system; The required torque of the transfer case is determined based on the torque of the multiple hydraulic pumps and the transfer case speed ratio. The total required torque of the engine is determined based on the required torque of the transfer case, the internal friction torque of the engine, and the auxiliary torque of the engine. If the total required torque is less than zero, it is determined that the power system has a negative load.

14. The power control method according to claim 13, characterized in that, The step of determining the negative load value of the power system when the power system is under negative load includes: When the total demand torque is less than zero, the total demand torque is determined as the negative load value of the power system; When the total required torque is greater than or equal to zero, the power system is determined to be without negative load.

15. The power control method according to claim 12, characterized in that, The step of determining the control parameters input to the pressure control valve group based on the negative load value of the power system includes: The balance load of the negative load balancing hydraulic circuit is determined based on the negative load value. The hydraulic oil pressure adjustment value at the outlet of the balancing hydraulic pump (10) is determined based on the balancing load. The control parameters are determined based on the hydraulic oil pressure adjustment value.

16. A power control method, characterized in that, Applied to the power system of claim 10, the power control method includes the following steps: When the output torque of the engine is greater than zero or the fuel consumption rate is greater than the first preset value A, the hydraulic oil pressure at the outlet of the balance hydraulic pump (10) is controlled to maintain the minimum hydraulic oil pressure. When the output torque of the engine is less than or equal to zero and the fuel consumption rate is less than the second preset value B, the hydraulic oil pressure at the outlet of the balance hydraulic pump (10) is gradually increased. Until the fuel consumption rate is greater than the third preset value C, the hydraulic oil pressure in the negative load balancing hydraulic circuit is controlled to no longer increase, where A > C > B.

17. A parameter matching method for a negative load balancing hydraulic circuit, characterized in that, Applied to the power system of claim 10, the parameter matching method includes: Obtain the maximum negative torque corresponding to the maximum negative load in the power system; Based on the maximum negative torque, determine the maximum working pressure in the negative load balancing hydraulic circuit; The displacement range of the balanced hydraulic pump (10) is determined based on the maximum working pressure; The working pressure range of the pressure control valve group is determined based on the displacement range of the balanced hydraulic pump (10) and the maximum working pressure.

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