Dual mode hydraulic control system based on variable pump and crane

Abstract

A dual-mode hydraulic control system and crane based on a variable pump, belonging to the field of hydraulic control technology. Its features include: a variable pump with a variable control port; a first control valve group connected to the outlet of the variable pump; a switching valve connected to the outlet of the variable pump; and an inlet of a second control valve group connected to the outlet of the switching valve, the switching valve controlling the on / off state of the oil circuit of the second control valve group. A first actuator is connected to the working port of the first control valve group, and a second actuator is connected to the working port of the second control valve group. A pressure feedback unit is connected to the variable control port of the first control valve group, the second control valve group, and the variable pump, respectively, and is used to feed back the highest load pressure signals of the first and second control valve groups to the variable pump. This invention controls multiple actuators through a single variable pump and switching valve, achieving both load-sensitive variable control and constant flow control modes, thus balancing system response speed, standby hydraulic circulation cooling, actuator control accuracy, and energy saving and cost reduction.

Description

Technical Field

[0001] This invention relates to a dual-mode hydraulic control system based on a variable pump and a crane, belonging to the field of hydraulic control technology. Background Technology

[0002] Currently, there are two main hydraulic control methods for multiple actuators (especially the upper working mechanism and the lower outrigger mechanism of a crane).

[0003] The first approach uses a single variable pump to control a set of multi-way valves, enabling multiple actuators to operate simultaneously. However, this approach, due to the use of a variable pump system, has a load-sensitive feedback (LS) circuit, resulting in a system response delay, low control sensitivity, and an inability to effectively achieve precise control of the actuators. For example, in a crane, the upper structure (such as boom luffing and telescopic mechanisms) and the lower structure (such as outrigger mechanisms) share the same variable pump system. For the lower structure actuators, which require rapid response, the delay impacts operational efficiency.

[0004] The second approach involves a multi-pump series control method, where multiple oil pumps control multiple sets of multi-way valves, enabling multiple actuators to operate simultaneously. However, this approach results in unnecessary energy consumption when the system does not require all actuators to operate simultaneously. For example, if the upper crane uses a variable displacement pump and the lower crane uses an independent fixed displacement pump, and the lower crane's outriggers are not in operation while the upper crane is in operation, the lower crane's independent fixed displacement pump continues to output flow, causing unnecessary energy consumption and increasing component costs.

[0005] Therefore, there is an urgent need in the existing technology for a hydraulic control system that can balance response speed, control accuracy, and energy consumption cost. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a dual-mode hydraulic control system and crane based on a variable pump. By controlling multiple actuators through a single variable pump and switching valve, it achieves two working modes: load-sensitive variable control and constant flow control, thereby balancing system response speed, standby hydraulic circulation cooling, actuator control accuracy, and energy saving and cost reduction.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: The first objective of this invention is to provide a dual-mode hydraulic control system based on a variable pump, comprising: a variable pump, a first control valve group, a switching valve, a second control valve group, a first actuator, a second actuator, and a pressure feedback unit.

[0008] The variable pump has a variable control port; the inlet of the first control valve group is connected to the outlet of the variable pump; the inlet of the switching valve is connected to the outlet of the variable pump; the inlet of the second control valve group is connected to the outlet of the switching valve; the switching valve is used to control the on / off state of the oil circuit of the second control valve group; the first actuator is connected to the working port of the first control valve group; the second actuator is connected to the working port of the second control valve group; the pressure feedback unit is connected to the first control valve group, the second control valve group, and the variable control port of the variable pump, respectively, and is used to feed back the highest load pressure signal of the first control valve group and the second control valve group to the variable pump.

[0009] In the above scheme, a single variable displacement pump simultaneously supplies hydraulic oil to both the first and second control valve groups, reducing the number of pumps and lowering costs and system complexity. A switching valve controls the on / off state of the oil circuit for the second control valve group, allowing the system to selectively supply oil to it as needed, avoiding unnecessary flow output and saving energy. The pressure feedback unit can feed back the highest load pressure signals of the first and second control valve groups to the variable displacement pump's control port, enabling the pump to adaptively adjust its displacement according to the actual workload, achieving on-demand oil supply and improving system efficiency.

[0010] Furthermore, the variable pump is a load-sensitive variable pump, which can automatically adjust the output flow and pressure according to the feedback pressure signal (LS signal).

[0011] Furthermore, the pressure feedback unit includes a shuttle valve, which has a simple structure and high reliability.

[0012] Furthermore, the first control valve group includes a load-sensitive proportional valve to achieve precise flow control of the first actuator (such as the main valve of the crane upper vehicle), and the load-sensitive proportional valve can be single or multiple.

[0013] Furthermore, the second control valve group includes a reversing valve group for controlling the direction of movement of the second actuator (such as the outrigger of a crane), and the reversing valve group is a single or multiple unit.

[0014] Furthermore, the second control valve assembly also includes a flow control valve, which is disposed between the switching valve and the reversing valve assembly. The flow control valve works in conjunction with the variable pump to ensure the variable pump outputs a constant flow rate when the switching valve is open, thus achieving a constant flow control mode.

[0015] Furthermore, it also includes an unloading valve, the oil inlet of which is connected to the oil outlet of the switching valve, and the oil outlet of which is connected to the oil tank.

[0016] Furthermore, the directional valve assembly is an open-center type directional valve. If the directional valve assembly uses an open-center type directional valve, that is, the directional valve assembly has an unloading function in the middle position, the unloading valve can be omitted.

[0017] Furthermore, it also includes a cooler, which is installed in the main return oil line of the hydraulic control system. All return oil must pass through the cooler, ensuring continuous heat dissipation of the hydraulic oil, effectively controlling the oil temperature, and extending the life of hydraulic components. A second objective of this invention is to provide a crane including the aforementioned dual-mode hydraulic control system based on a variable pump, wherein the first actuator is an upper-car actuator, the second actuator is an lower-car actuator, the first control valve group is the upper-car main valve, and the second control valve group is the lower-car main valve.

[0018] This crane uses a single variable pump to simultaneously control the upper carriage (boom luffing, telescopic, etc.) and lower carriage (outrigger) actuators, saving the need for an oil pump and reducing costs.

[0019] The hydraulic control system of this invention is applied to cranes, and its cooling and heat dissipation working principle is as follows: 1. When the down-vehicle main valve is a reversing valve assembly in the neutral position without unloading, and the entire system is equipped with an unloading valve and a cooler, then: 1) When the crane is in operation (both the upper and lower parts are in operation), the unloading valve solenoid DT2 is de-energized, the unloading valve does not function, and the total return oil of the hydraulic system passes through the cooler to achieve cooling during operation; 2) When the crane is in standby mode (neither the upper nor lower vehicle is working, but the crane engine is running), if the system oil needs to be cooled, the switching valve solenoid DT1 and the unloading valve solenoid DT2 are energized. The oil output by the variable pump returns to the oil tank through the switching valve and the unloading valve and then through the cooler, realizing standby low-pressure circulation cooling and continuously cooling the oil.

[0020] 2. If the current main valve is an open-center reversing valve, and the entire system is equipped with a cooler (unloading valve is removed), then: 1) When the crane is in operation (both the upper and lower parts are in operation), the total return oil of the hydraulic system passes through the cooler to achieve cooling during operation; 2) When the crane is in standby mode (neither the upper nor lower carriage is working, but the crane engine is running), if the system oil needs to be cooled, the switching valve solenoid DT1 is energized, and the oil output by the variable pump passes through the switching valve, the open center-type directional valve (in the neutral position), and then back to the oil tank through the cooler, realizing standby low-pressure circulation cooling and continuously cooling the oil.

[0021] This invention uses a variable displacement pump (load-sensitive variable displacement pump) as the hydraulic power source. The outlet of the variable displacement pump is connected to the inlet of both the first control valve group and the switching valve. The switching valve can be a two-position, two-way solenoid valve used to control the on / off state of the oil circuit of the second control valve group.

[0022] First operating mode (load-sensitive variable control): The hydraulic oil output from the variable pump enters the first control valve group, which includes load-sensitive proportional valves (single or multiple), enabling precise control of multiple actuators. The load feedback pressure (LS signal) output by the load-sensitive proportional valve enters the variable control port of the variable pump via the shuttle valve. The variable pump adaptively adjusts its displacement according to the load pressure, achieving on-demand oil supply.

[0023] Second working mode (constant flow control): When the switching valve is energized, the oil circuit of the second control valve group is connected. A portion of the hydraulic oil output by the variable pump enters the second control valve group through the switching valve. It first passes through the flow control valve, and the outlet pressure of the flow control valve is fed back to the variable control port of the variable pump through the shuttle valve. The main oil circuit of the flow control valve is connected to the directional valve group (single or multiple), realizing constant flow control of multiple actuators.

[0024] This invention utilizes a variable pump and a switching valve to achieve both load-sensitive variable control and constant-flow control, meeting the control requirements of various complex actuators. It features a simple structure, convenient operation, ease of implementation, and cost reduction. When neither the upper nor lower vehicle is operating, the variable pump provides a low-pressure constant-flow oil source, which is then cooled by a cooler to achieve standby low-pressure circulation cooling, continuously lowering the hydraulic oil temperature and solving the system's heat dissipation problem. Attached Figure Description

[0025] Figure 1 This is a control principle diagram from Embodiment 1 of the present invention; Figure 2 This is a control principle diagram from Embodiment 2 of the present invention; Figure 1 In the middle: 1-Load-sensitive variable pump, 2-Switching valve, 3-Flow control valve, 4-Shuttle valve, 5-Upper main valve (load-sensitive proportional valve), 6-Lower main valve (directional valve assembly, no unloading in the middle position), 7-Cooler, 8-Unloading valve, 10-Boom telescopic cylinder assembly, 11-Boom luffing cylinder assembly, 12-Horizontal outrigger cylinder, 13-Vertical outrigger cylinder; Figure 2 In the middle: 1-Load-sensitive variable pump, 2-Switching valve, 3-Flow control valve, 4-Shuttle valve, 5-Upper main valve (load-sensitive proportional valve), 7-Cooler, 9-Open center-type directional valve (neutral unloading), 10-Boom telescopic cylinder assembly, 11-Boom luffing cylinder assembly, 12-Horizontal outrigger cylinder, 13-Vertical outrigger cylinder. Detailed Implementation

[0026] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Example

[0027] like Figure 1 As shown, a dual-mode hydraulic control system based on a variable pump, applied to a crane, includes: a load-sensitive variable pump 1, a switching valve 2, a flow control valve 3, a pressure feedback unit (using a shuttle valve 4), a first control valve group 5 (i.e., the upper main valve, using a load-sensitive proportional valve), a second control valve group 6 (i.e., a directional valve group, with no unloading in the neutral position), a first actuator (including a boom telescopic cylinder group 10, a boom luffing cylinder group 11, etc.), and a second actuator (including a horizontal outrigger cylinder 12 and a vertical outrigger cylinder 13).

[0028] The connection relationships of this system: The load-sensitive variable pump 1 serves as a power source, and its oil outlet is connected to the load-sensitive proportional valve 5 and the switching valve 2, respectively. The working port of the load-sensitive proportional valve 5 is connected to the first actuator, and the load feedback port (LS) of the load-sensitive proportional valve 5 is connected to one input port of the shuttle valve 4. The oil outlet of switching valve 2 is connected to the oil inlet of flow control valve 3, and the oil outlet of flow control valve 3 is connected to the oil inlet of reversing valve group 6 and another input port of shuttle valve 4 respectively. The outlet of shuttle valve 4 is connected to the variable control port of load-sensitive variable pump 1. The two input ports of shuttle valve 4 are connected to the load feedback port (LS) of load-sensitive proportional valve 5 and the outlet of flow control valve 3, respectively, to feed back the higher load pressure signal of the two to the variable pump. The working oil port of the reversing valve group 6 is connected to the second actuator.

[0029] The working process of this system: During the loading process: the variable pump adopts a load-sensitive variable control mode.

[0030] When the electromagnet DT1 of switching valve 2 is de-energized, the oil supply from load-sensitive variable pump 1 to the lower outriggers is cut off, and the oil output from load-sensitive variable pump 1 is only supplied to the upper main valve, ensuring the oil supply required by each actuator of the upper vehicle.

[0031] The load-sensitive variable pump achieves adaptive control through load pressure feedback (LS). During system operation, the load-sensitive proportional valve collects the real-time load pressure of the actuator and feeds it back to the variable control port of the variable pump through the LS control oil circuit. The variable pump compares the outlet pressure with the feedback load pressure and automatically adjusts the output displacement and oil supply pressure according to the pressure difference.

[0032] When working off the vehicle: constant current control mode.

[0033] When the electromagnet DT1 of switching valve 2 is energized, the pressure oil from the lowering outrigger is fed back to the LS port of load-sensitive variable pump 1 through shuttle valve 4. Load-sensitive variable pump 1 supplies a constant flow according to the requirements of flow control valve 3, ensuring the flow required by the lowering outrigger actuator. This constant flow enters the reversing valve group 6 through switching valve 2 and flow control valve 3, realizing constant flow operation.

[0034] Preferably, it also includes a cooler 7 and an unloading valve 8, the oil inlet of the unloading valve being connected to the oil outlet of the flow control valve 3, and the oil outlet of the unloading valve being connected to the oil tank via the cooler.

[0035] The cooler is installed in the main return oil circuit of the hydraulic control system. Regardless of whether the vehicle is loading or unloading, the main return oil passes through the cooler, which can continuously cool the oil as needed. When the vehicle is not loading or unloading and is in standby mode, if the hydraulic oil needs to be cooled, the solenoid DT1 of the switching valve 2 and the solenoid DT2 of the unloading valve can be energized. The variable pump will then output a low-pressure constant flow rate to the cooler for circulation and cooling, thus meeting the continuous cooling requirements of the hydraulic fluid. Example

[0036] Unlike Example 1, as Figure 2 As shown, if the main valve at the bottom has an unloading function in the center position, such as the directional valve group using an open center-type directional valve 9, the unloading valve can be eliminated.

[0037] When the open-center directional valve is in the neutral position: the output flow returns directly to the oil tank through the valve core in the neutral position, and the system is in a low-pressure standby state; in addition, the oil output by the variable pump returns to the oil tank through the switching valve, the open-center directional valve, and the cooler, realizing low-pressure circulation cooling in standby mode. When the open-center directional valve 7 is in operation, it redistributes the flow according to the opening degree of the valve core.

Claims

1. A dual-mode hydraulic control system based on a variable pump, characterized in that, include: Variable displacement pump, with variable displacement control port; The first control valve group is connected to the oil outlet of the variable pump; A switching valve, the oil inlet of which is connected to the oil outlet of the variable pump; The second control valve group is connected to the oil outlet of the switching valve, and the switching valve is used to control the on / off of the oil circuit of the second control valve group. The first actuator is connected to the working oil port of the first control valve group; The second actuator is connected to the working oil port of the second control valve group; The pressure feedback unit is connected to the first control valve group, the second control valve group, and the variable control port of the variable pump, respectively, and is used to feed back the highest load pressure signal of the first control valve group and the second control valve group to the variable pump.

2. The dual-mode hydraulic control system based on a variable pump according to claim 1, characterized in that: The variable pump is a load-sensitive variable pump.

3. The dual-mode hydraulic control system based on a variable pump according to claim 1, characterized in that: The pressure feedback unit includes a shuttle valve.

4. A dual-mode hydraulic control system based on a variable pump according to claim 1, characterized in that: The first control valve group includes a load-sensitive proportional valve, which can be a single or multiple valves.

5. A dual-mode hydraulic control system based on a variable pump according to claim 1, characterized in that: The second control valve group includes a reversing valve group, which can be a single or multiple reversing valve group.

6. A dual-mode hydraulic control system based on a variable pump according to claim 5, characterized in that: The second control valve assembly further includes a flow control valve, which is disposed between the switching valve and the reversing valve assembly.

7. A dual-mode hydraulic control system based on a variable pump according to claim 6, characterized in that: It also includes an unloading valve, the oil inlet of which is connected to the oil outlet of the switching valve, and the oil outlet of which is connected to the oil tank.

8. A dual-mode hydraulic control system based on a variable pump according to claim 6, characterized in that: The reversing valve assembly is an open-center type reversing valve.

9. A dual-mode hydraulic control system based on a variable pump according to claim 1, characterized in that: It also includes a cooler, which is located on the main return line of the hydraulic control system.

10. A crane, characterized in that: The system includes a dual-mode hydraulic control system based on a variable pump as described in any one of claims 1 to 9, wherein the first actuator is an upper actuator and the second actuator is an lower actuator.

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