Load-sensing based hydraulic control system, control method, and working machine

Abstract

The application provides a load-sensitive hydraulic control system, a control method and a working machine. The hydraulic control system comprises a main pump, a plurality of actuators, a load-sensitive main valve comprising a plurality of main throttles corresponding to the plurality of actuators and a plurality of first pilot ports, an oil inlet of the main throttle being connected to an oil outlet of the pump, an oil outlet of the main throttle being connected to a corresponding actuator, an overflow valve group having a second pilot port, an overflow oil inlet and an overflow oil outlet, and a controller connected to the main pump, the main throttle and the overflow valve group, respectively. In a throttle speed control mode, the controller controls the displacement of the main pump according to the opening of the main throttle and the flow pressure difference of the overflow valve group until the overflow valve group maintains a constant pressure difference. By converting the flow signal of the bypass overflow into a pressure signal and adjusting the flow of the main pump through negative flow control, the load-sensitive system's flow distribution function is inherited, and the positive flow's rapid response characteristics are also possessed.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology, and more specifically to a load-sensitive hydraulic control system, control method, and working machinery. Background Technology

[0002] Currently, load-sensitive systems and positive flow systems are widely used in construction machinery. Load-sensitive systems employ load-sensitive main valves and load-sensitive main pumps, and through closed-loop variable regulation, there is no flow waste, resulting in high energy efficiency.

[0003] In existing technologies, load-sensitive systems maintain a relatively constant pressure difference across the main valve core, enabling flow distribution based on the opening area, unaffected by load, and ensuring coordinated operation of multiple actions. However, due to the relatively long time required for pressure feedback, the overall system response is slow, making it impossible to achieve independent or proportional flow distribution based on valve orifice size in multi-action interconnected conditions. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art, which is that the overall system response is slow and the flow rate cannot be independently or proportionally distributed according to the valve port in multi-action interconnection conditions. Thus, the present invention provides a load-sensitive hydraulic control system that can improve the response speed and achieve the function of independently or proportionally distributed according to the valve port in multi-action interconnection conditions.

[0005] To address the aforementioned problems, this invention provides a load-sensitive hydraulic control system, comprising: a main pump having a pump inlet, a pump outlet, and a control terminal, wherein the pump inlet is connected to an oil tank; multiple actuators; a load-sensitive main valve including multiple main throttle ports corresponding one-to-one with the actuators and multiple first pilot ports, wherein the first pilot ports are adapted to acquire the highest pressure of the actuators, the inlets of the main throttle ports are connected to the pump outlet, and the outlets of the main throttle ports are connected to the corresponding actuators; and a relief valve assembly having a second pilot port, a relief inlet, and a relief outlet. The second pilot port is adapted to obtain the highest pressure of the corresponding actuator. The overflow inlet is connected to the inlet of the main throttle port and the outlet of the pump. The hydraulic oil flowing through the overflow inlet and the outlet forms a flow-pressure difference, which acts on the control terminal. The overflow outlet is connected to the oil tank. The controller is connected to the control terminal and the main throttle port respectively. In the throttle speed control mode, the controller is adapted to control the displacement of the main pump according to the opening of the main throttle port and the flow-pressure difference of the overflow valve group until the overflow valve group and the load-sensitive main valve maintain a constant pressure difference.

[0006] Preferably, the overflow valve assembly includes: a flow compensation valve having a second pilot port, an overflow inlet port, and an overflow outlet port; a damping structure connected to the overflow outlet port to create the flow-pressure difference by means of hydraulic oil exiting the overflow outlet port, and the outlet port of the damping structure being connected to the oil tank; wherein, the control terminal is connected to the inlet port of the damping structure and the overflow outlet port through an overflow oil circuit, so that the flow-pressure difference acts on the control terminal.

[0007] Preferably, the overflow valve assembly further includes a safety valve connected in parallel with the damping structure.

[0008] Preferably, the overflow valve assembly further includes a throttle valve, and the damping structure is disposed within the throttle valve.

[0009] Preferably, the load-sensitive hydraulic control system further includes a check valve, which is connected to the inlet and outlet of the damping structure via the overflow oil passage, and the flow rate pressure difference is applied to the control terminal via the overflow oil passage.

[0010] Preferably, the load-sensitive main valve further includes multiple pressure compensation valves corresponding to the plurality of actuators. The oil outlet of the main throttle port is connected to the corresponding actuator through the corresponding pressure compensation valve. A first spring is provided on one side of the valve core of the pressure compensation valve. The relief valve group is provided with a relief valve core, and a second spring is provided on one side of the relief valve core. The load-sensitive hydraulic control system further includes a pressure selection valve adapted to obtain the maximum load pressure. The pressure selection valve is connected to the oil inlet of the actuator, the side of the valve core of the pressure compensation valve with the first spring, and the side of the relief valve core with the second spring, respectively. The other side of the relief valve core is adapted to connect to the pressure of the pump outlet, so that the pump outlet pressure after the relief valve core is balanced forms a constant value with the maximum load pressure. The other side of the valve core of the pressure compensation valve is connected to the pressure after the main valve of the load-sensitive main valve, so that the pressure before and after the load-sensitive main valve after the valve core of the pressure compensation valve is constant.

[0011] Preferably, the load-sensitive hydraulic control system further includes a control valve connected to the pressure compensation valve and the controller. In the volumetric speed control mode, the controller is adapted to control the opening of the main throttle port to the maximum and control the opening of the pressure compensation valve to the maximum through the control valve. The controller also controls the cutting off of the hydraulic oil circuit entering the relief valve assembly.

[0012] Preferably, the load-sensitive hydraulic control system further includes a shut-off valve, which is communicatively connected to the controller so that the controller controls the opening or closing of the shut-off valve.

[0013] Preferably, the load-sensitive hydraulic control system further includes a flow control valve, the inlet of which is connected to the outlet of the pump and the inlet of the main throttle port, the outlet of which is connected to the outlet of the pressure compensation valve, and the flow control valve is connected to the controller, which is adapted to control the flow control valve to open to cut off the hydraulic oil circuit entering the relief valve assembly.

[0014] The present invention also provides a load-sensitive hydraulic control method, comprising: acquiring the opening degree of the main throttle orifice and controlling the displacement of the main pump to be higher than the load demand; acquiring the flow rate pressure difference of hydraulic oil flowing through the overflow inlet and overflow outlet of the relief valve assembly; in the throttle speed control mode, controlling the displacement of the main pump according to the acquired opening degree of the main throttle orifice, and forming a negative feedback function of the relief valve assembly through the flow rate pressure difference to control the displacement of the main pump, until the pressure difference of the relief valve assembly and the pressure difference before and after the main throttle orifice are kept constant, so as to realize the flow distribution function of the load-sensitive system.

[0015] Preferably, the load-sensitive hydraulic control method further includes: controlling a pressure compensation valve to obtain the highest load pressure of multiple actuators, and after the valve core of the pressure compensation valve is balanced, the pressure before and after the load-sensitive main valve is constant; controlling a flow compensation valve to obtain the highest load pressure, and after the valve core of the flow compensation valve is balanced, a constant value is formed between the pressure at the pump outlet and the highest load pressure.

[0016] Preferably, the load-sensitive hydraulic control method further includes, in volumetric speed regulation mode, controlling the opening of the pressure compensation valve and the opening of the main throttle port to the maximum, and cutting off the oil circuit of the hydraulic oil entering the relief valve group.

[0017] The present invention also provides a working machine, including: a load-sensitive hydraulic control system as described in any one of the claims.

[0018] The present invention has the following advantages:

[0019] 1. By utilizing the technical solution of the present invention, under the linkage condition, the flow signal of the bypass overflow in the main circuit is converted into a pressure signal, and the flow of the main pump is restored through negative flow control. This inherits the flow distribution function of the load-sensitive system and has the characteristic of rapid response to positive flow.

[0020] 2. By connecting a safety valve in parallel with the throttle valve, the functionality of the throttle valve can be guaranteed.

[0021] 3. By opening the pressure compensation valve and the main throttle port to the maximum in single-action mode, and simultaneously disabling the compensation function of the flow compensation valve, the obstruction between the main pump and the actuator is removed. This reduces pressure loss and improves system efficiency when starting the positive flow system function.

[0022] 4. By using a load-sensitive main valve connected in parallel with a bypass passage and controlling the flow rate into the actuator through a flow control valve, the flow rate is prevented from entering the relief valve assembly, thereby cutting off the oil circuit of the relief valve assembly and simplifying the control process. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram illustrating the principle of a load-sensitive hydraulic control system according to one embodiment of the present invention.

[0025] Figure 2 This is a flowchart of a load-sensitive hydraulic control method according to one embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 110. Main pump; 120. Actuator; 130. Load-sensitive main valve; 131. Main throttle port; 133. Pressure compensation valve; 1331. First spring; 135. First pilot port; 140. Relief valve assembly; 141. Flow compensation valve; 1411. Second spring; 143. Throttle valve; 145. Safety valve; 147. Second pilot port; 151. Controller; 153. Check valve; 160. Shut-off valve; 170. Pressure selector valve; 180. Control valve; 190. Oil tank. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Application Overview

[0030] In the relevant existing technology, although the function of a positive flow system is realized because a fixed pressure difference is formed on both sides of the main valve core, some capacity will be lost due to the fixed pressure loss of the load-sensitive system.

[0031] Example 1

[0032] like Figure 1 As shown, a load-sensitive hydraulic control system includes: a main pump 110, multiple actuators 120, a load-sensitive main valve 130, a relief valve group 140, and a controller 151. The main pump 110 has a pump inlet, a pump outlet, and a control terminal. The pump inlet is connected to an oil tank 190 to allow oil to enter from the oil tank 190 through the pump inlet, thereby supplying oil to the entire control oil circuit. The load-sensitive main valve 130 includes multiple main throttle ports 131 corresponding to multiple actuators 120 and multiple first pilot ports 135. The first pilot ports 135 are adapted to obtain the highest pressure of the multiple actuators 120. The inlet of the main throttle port 131 is connected to the outlet of the pump, so that hydraulic oil can enter the inlet of the main throttle port 131 after flowing out of the outlet of the pump. The outlet of the main throttle port 131 is connected to the corresponding actuator 120, so that hydraulic oil can enter the actuator 120 after flowing out of the outlet of the main throttle port 131. The overflow valve assembly 140 has a second pilot port 147, an overflow inlet port, and an overflow outlet port. The second pilot port 147 is adapted to obtain the highest pressure of the corresponding actuator 120. The overflow inlet port is connected to the inlet port of the main throttle port 131 and the pump outlet port. The hydraulic oil flowing through the overflow inlet port and the outlet port forms a flow-pressure difference, which acts on the control terminal. The overflow outlet port is connected to the oil tank 190. The controller 151 is connected to the control terminal, the main throttle port 131, and the overflow valve assembly 140, respectively. In the throttling speed control mode, the controller 151 is adapted to control the discharge of the main pump 110 according to the opening degree of the main throttle port 131 and the flow-pressure difference of the overflow valve assembly 140, until the overflow valve assembly 140 and the load-sensitive main valve 130 maintain a constant pressure difference, respectively.

[0033] The aforementioned load-sensitive hydraulic control system forms the main circuit, with an overflow bypass installed in the main circuit. An overflow valve assembly 140 is connected in series with the overflow bypass. When the flow rate of the hydraulic oil at the pump outlet exceeds the flow rate required by the pressure difference of the overflow valve assembly 140, the hydraulic oil enters the overflow bypass. When the entire machine performs a compound operation involving multiple actuators 120 working together, a throttling speed control mode is adopted. The opening degree of the main throttling orifice 131 can be obtained through a displacement sensor installed in the load-sensitive main valve 130, and the opening size of the main throttling orifice 131 can be detected by the displacement sensor. The opening degree of the main throttling orifice 131 can also be calculated based on the known correspondence between the opening size of the main throttling orifice 131 and the valve core offset distance. The main pump 110 can be an electro-proportional displacement pump or a positive flow pump, providing hydraulic oil to the hydraulic control system. The control terminal of the main pump 110 can be used to control the displacement of the main pump 110. When the controller 151 controls the displacement of the main pump 110 according to the opening of the main throttle port 131, and makes the displacement of the main pump 110 higher than the flow rate required for the pressure difference formed by the relief valve assembly 140, hydraulic oil will enter the relief valve assembly 140. Based on the flow-pressure difference formed by the relief valve assembly 140, a negative feedback function is formed in the relief valve assembly 140, which acts on the control terminal to control the displacement of the main pump 110. The greater the flow rate, the greater the flow-pressure difference formed by the hydraulic oil flowing through the relief inlet and outlet. The control terminal controls the main pump 110 to reduce its displacement, thus reducing the flow rate overflowing from the relief valve assembly 140, until the relief valve assembly 140 maintains a constant pressure difference between the maximum pressure among the multiple actuators 120 and the pressure at the pump outlet. Furthermore, the load-sensitive main valve 130 can maintain a constant pressure difference between the maximum pressure among the multiple actuators 120 and the pressure at the pump outlet. Because the positive flow control function of the main pump 110 is activated, there is no load pressure feedback time. Therefore, the response time of the load-sensitive hydraulic control system depends only on the response time of the main pump 110 itself, thereby improving the response speed. Simultaneously, since the main valve and the relief valve assembly 140 form a load-sensitive system, the flow rate can be distributed to each actuator 120 according to the opening degree or proportion of the main throttle port 131, meeting the linkage requirements in the throttle speed control mode.

[0034] Furthermore, the relief valve assembly 140 includes: a flow compensation valve 141 and a damping structure. The flow compensation valve 141 has a second pilot port 147, a relief inlet port, and a relief outlet port. The damping structure is connected to the relief outlet port so that the hydraulic oil coming out of the relief outlet port forms a flow-pressure difference. The outlet port of the damping structure is connected to the oil tank 190. The control end of the main pump 110 is connected to the inlet port and the relief outlet port of the damping structure through the relief oil circuit so that the flow-pressure difference acts on the control end.

[0035] The aforementioned flow compensation valve 141 can be a three-way flow valve, having an inlet, an outlet, and a pilot port. The inlet of the flow compensation valve 141 is connected to the pump outlet and the inlet of the main throttle port 131. The outlet of the flow compensation valve 141 is connected to the inlet of the damping structure. The second pilot port 147 is connected to the pressure selection valve 170 to apply the maximum pressure of the actuator 120 to the pilot port. The pressure of the pump outlet acts on the flow compensation valve 141 through the inlet of the flow compensation valve 141, so that the flow compensation valve 141 can be maintained under a constant pressure.

[0036] Hydraulic oil from the pump outlet enters the overflow outlet through the overflow inlet. Under the action of the damping structure, the flow signal of the hydraulic oil entering the overflow valve assembly 140 is converted into a pressure signal, creating a flow-pressure difference. The oil overflowing from the flow compensation valve 141 experiences increased pressure due to the damping effect of the damping structure. The greater the flow rate, the greater the pressure, thus increasing the pressure of the main pump 110. This reduces the output flow rate of the main pump 110, further decreasing the amount of oil overflowing from the flow compensation valve 141 and lowering the pressure before the damping structure. Therefore, the back pressure formed by the oil overflowing from the flow compensation valve 141 controls the pump flow rate, creating a balanced constant value between the load end pressure and the pump outlet pressure. This constant value can be the spring setting value of the flow compensation valve 141. The overflow valve assembly 140 also includes a safety valve 145, which is connected in parallel with the damping structure.

[0037] The aforementioned overflow valve assembly 140 also includes a throttle valve 143, with a damping structure disposed within the throttle valve 143. Oil overflowing from the overflow outlet of the flow compensation valve 141 can create back pressure through the throttle valve 143, thereby converting the flow signal into a pressure signal. The greater the flow rate entering the overflow inlet, the higher the pressure.

[0038] Furthermore, it also includes a one-way valve 153, which is connected to the inlet and outlet of the damping structure through an overflow oil passage. The flow rate and pressure difference act on the control end through the overflow oil passage. In addition, the one-way valve 153 also ensures that the pilot oil inside the main pump 110 does not flow out into the overflow valve assembly 140.

[0039] The aforementioned load-sensitive main valve 130 can be a multi-way directional valve that distributes flow to multiple actuators 120. It can output pilot pressure to the pressure selection valve 170 by controlling the stroke of the pedal or handle according to specific operating conditions. The controller 151 is preferably an electronically controlled proportional displacement controller 151 that proportionally adjusts the displacement of the main pump 110 by controlling the magnitude of the input current; alternatively, it can be a hydraulically controlled proportional displacement controller 151 that proportionally adjusts the displacement of the main pump 110 by controlling the magnitude of the input fluid pressure. Hydraulic oil flowing out through the overflow port can act on the swashplate plunger of the main pump 110 through the check valve 153, thereby adjusting the displacement of the main pump 110.

[0040] Furthermore, the load-sensitive main valve 130 also includes multiple pressure compensation valves 133, each corresponding to one of the multiple actuators 120. The oil outlet of the main throttle port 131 is connected to the corresponding actuator 120 through the corresponding pressure compensation valve 133. A first spring 1331 is provided on one side of the valve core of the pressure compensation valve 133. The relief valve assembly 140 is provided with a relief valve core, and a second spring 1411 is provided on one side of the relief valve core. The load-sensitive hydraulic control system also includes a pressure selection valve 170 suitable for obtaining the highest load pressure. 70 is connected to the oil inlet of the actuator 120, the valve core of the pressure compensation valve 133 is set on one side of the first spring 1331 and the overflow valve core is set on one side of the second spring 1411 respectively. The other side of the overflow valve core is adapted to connect to the pressure of the pump outlet, so that the pump outlet pressure after the overflow valve core is balanced forms a constant value with the maximum load pressure. The other side of the valve core of the pressure compensation valve 133 is connected to the pressure after the main valve of the load-sensitive main valve 130, so that the pressure before and after the load-sensitive main valve 130 is constant after the valve core of the pressure compensation valve 133 is balanced.

[0041] The aforementioned pressure compensation valve 133 and flow compensation valve 141 constitute a downstream load-sensitive system. The pressure selection valve 170 includes a shuttle valve assembly. The principle of the load-sensitive system is as follows: the highest pressure of each actuator 120, i.e., the highest load pressure, is selected through the shuttle valve assembly. The highest load pressure acts on one end of the pressure compensation valve 133 and simultaneously on one end of the flow compensation valve 141. The other end of the flow compensation valve 141 is connected to the pump outlet pressure. After the valve core of the flow compensation valve 141 is balanced, a constant value is formed between the pump outlet pressure and the highest load pressure. One end of 133 is connected to the highest load pressure, and the other end is connected to the pressure after the main valve. After the valve core of the pressure compensation valve 133 reaches balance, the pressure after the main valve in the circuit of each actuator 120 is the same, that is, the set value of the first spring 1331 of each pressure compensation valve 133 is the same. Combined with the function of the flow compensation valve 141, the pressure before and after the main valve is constant. The constant pressure difference value is the set value of the second spring 1411 of the flow compensation valve 141. Thus, the flow of each actuator can be distributed according to the opening size of the main valve or proportionally according to the opening size, realizing the flow distribution function of the load sensitive system.

[0042] Furthermore, the load-sensitive hydraulic control system also includes a control valve 180, which is connected to the controller 151 and the pressure compensation valve 133. In the volumetric speed control mode, the controller 151 is adapted to control the opening of the main throttle port 131 to the maximum and control the opening of the pressure compensation valve 133 to the maximum through the control valve 180. The controller 151 also controls the cutting off of the hydraulic oil circuit entering the relief valve assembly 140.

[0043] Furthermore, the load-sensitive hydraulic control system also includes a shut-off valve 160, which is communicatively connected to the controller 151 so that the controller 151 can control the opening or closing of the shut-off valve 160. The shut-off valve 160 is located on the overflow bypass and can be a switching valve. In volumetric speed control mode, the controller 151 can control the shut-off valve 160 to close, preventing the hydraulic oil from the pump outlet from entering the overflow valve assembly 140, thereby interrupting the overflow bypass of the main circuit.

[0044] Furthermore, as an alternative to installing a shut-off valve 160 on the overflow bypass, the load-sensitive hydraulic control system also includes a flow control valve. The inlet of the flow control valve is connected to the pump outlet and the inlet of the main throttle port 131, and the outlet of the flow control valve is connected to the outlet of the pressure compensation valve 133. The flow control valve is communicatively connected to a controller 151, which is adapted to control the flow of the flow control valve to cut off the hydraulic oil circuit entering the overflow valve assembly 140.

[0045] The aforementioned flow control valve is connected in parallel with the load-sensitive main valve 130. When the controller 151 opens the flow control valve, the hydraulic oil at the pump outlet enters the flow control valve and then flows from the flow control valve into the actuator 120, disabling the relief valve assembly 140 and thus locking the main circuit. The greater the pressure difference between the pressure of the hydraulic oil at the pump outlet and the pressure of the required flow rate of the actuator 120, the greater the flow rate of the flow control valve. When the controller 151 controls the flow control valve to open, allowing hydraulic oil to enter the actuator 120, the hydraulic oil will not enter the relief bypass, effectively cutting off the relief bypass and preventing the relief valve assembly 140 on the relief bypass from causing pressure loss to the hydraulic oil. When the main pump 110 is activated, the positive flow system function can be achieved with minimal pressure loss, thereby eliminating the fixed pressure loss of the load-sensitive system and improving efficiency.

[0046] Example 2

[0047] like Figure 2 As shown, a load-sensitive hydraulic control method includes the following steps:

[0048] Step S101: Obtain the opening degree of the main throttle port 131 and control the discharge of the main pump 110 to be higher than the load demand;

[0049] Step S103: Obtain the flow rate and pressure difference of the hydraulic oil after flowing through the overflow inlet and overflow outlet of the overflow valve assembly 140;

[0050] Step S105: In the throttling speed control mode, the discharge of the main pump 110 is controlled according to the opening degree of the main throttling port 131, and the negative feedback function of the overflow valve group 140 is formed through the flow pressure difference to control the discharge of the main pump 110 until the pressure difference of the overflow valve group 140 and the pressure difference before and after the main throttling port 131 are kept constant, so as to realize the flow distribution function of the load sensitive system.

[0051] Specifically, the load-sensitive hydraulic control method also includes the following steps:

[0052] Step S201: Control the pressure compensation valve 133 to obtain the highest load pressure of multiple actuators 120, and after the valve core of the pressure compensation valve 133 is balanced, the pressure before and after the load sensitive main valve 130 is constant.

[0053] Step S203: Control the flow compensation valve to obtain the maximum load pressure, and after the valve core of the flow compensation valve is balanced, a constant value is formed between the pressure at the pump outlet and the maximum load pressure.

[0054] When the above-mentioned throttling speed control mode is adopted, the displacement of the main pump 110 can be controlled by the opening degree of the main throttling port 131, so that the displacement of the main pump 110 is higher than the load demand. The load demand can be determined by the first spring 1331 set on one side of the valve core of the pressure compensation valve 133 and the second spring 1411 set on one side of the valve core of the flow compensation valve 141. The first spring 1331 and the second spring 1411 each have set values, thus revealing the load demand. Under the linkage condition, the flow signal from the bypass overflow in the main circuit is converted into a pressure signal, and the flow is redirected through negative flow control, inheriting the flow distribution function of the load-sensitive system while possessing the characteristic of rapid response to positive flow.

[0055] Furthermore, the load-sensitive hydraulic control method also includes, in the volumetric speed regulation mode, controlling the opening of the pressure compensation valve 133 and the main throttle port 131 to the maximum, and cutting off the oil circuit of the hydraulic oil entering the relief valve group 140, so that in the single-action condition, the main throttle port 131 of the load-sensitive main valve 130 and the pressure compensation valve 133 are opened to the maximum, completely opening the obstruction between the oil pump and the actuator 120, realizing the volumetric speed regulation function of the positive flow system, which has the characteristics of fast response and improved efficiency.

[0056] Example 3

[0057] A working machine, including any one of the load-sensitive hydraulic control systems.

[0058] The aforementioned work machinery can be controlled by a load-sensitive hydraulic control system without relying on load pressure, thus improving its adaptability. The work machinery can include excavators, pile drivers, etc. By combining a positive flow system and a load-sensitive system, the work machinery enables the load-sensitive hydraulic control system to have rapid response, independent or proportional flow distribution, and energy efficiency under specific operating conditions.

[0059] Based on the above description, the present invention has the following advantages:

[0060] 1. By setting an overflow bypass in the main circuit, the overflow valve group 140 is connected in series in the overflow bypass. When the flow rate of hydraulic oil at the pump outlet is greater than the flow rate required by the pressure difference of the overflow valve group 140, the hydraulic oil will enter the overflow bypass. The displacement of the main pump 110 is controlled according to the opening of the main throttle port 131 and the pressure difference formed in the overflow bypass until the overflow valve group 140 maintains a constant pressure difference between the maximum pressure among the multiple actuators 120 and the pressure at the pump outlet. There is no load pressure feedback time. Therefore, the response time of the load-sensitive hydraulic control system depends only on the response time of the main pump 110 itself, thereby improving the response speed. At the same time, since the main valve and the overflow valve group 140 form a load-sensitive system, the flow rate can be distributed to each actuator 120 according to the opening of the main throttle port 131 or proportionally, which meets the linkage requirements in the throttling speed control mode.

[0061] 2. By connecting the throttle valve 143 in parallel with the safety valve 145, the functionality of the throttle valve 143 can be guaranteed.

[0062] 3. By applying pilot pressure to the pressure compensation valve 133 of the load-sensitive main valve 130 and the flow compensation valve 141 of the relief valve group 140, and closing the relief bypass after opening the main throttle port 131 and the pressure compensation valve 133 to their maximum, the positive flow system function is achieved with minimal pressure loss, eliminating the fixed pressure loss of the load-sensitive system and improving efficiency.

[0063] 4. By using the load-sensitive main valve 130 to bypass the passage in parallel and controlling the flow rate into the actuator through the flow control valve, the flow rate cannot enter the relief valve group 140, thereby cutting off the oil circuit of the relief valve group 140 and simplifying the control process.

[0064] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0065] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0067] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A load-sensitive hydraulic control system, characterized in that, include: The main pump (110) has a pump inlet, a pump outlet and a control terminal, wherein the pump inlet is connected to the oil tank (190); Multiple implementing agencies (120); The load-sensitive main valve (130) includes multiple main throttle ports (131) corresponding one-to-one with multiple actuators (120) and multiple first pilot ports (135). The first pilot ports (135) are adapted to obtain the maximum pressure of multiple actuators (120). The inlet of the main throttle port (131) is connected to the outlet of the pump, and the outlet of the main throttle port (131) is connected to the corresponding actuator (120). The overflow valve assembly (140) has a second pilot port (147), an overflow inlet port and an overflow outlet port. The second pilot port (147) is adapted to obtain the highest pressure of the corresponding actuator (120). The overflow inlet port is connected to the inlet port of the main throttle port (131) and the outlet port of the pump. The hydraulic oil flowing through the overflow inlet port and the outlet port forms a flow pressure difference. The flow pressure difference acts on the control end. The overflow outlet port is connected to the oil tank (190). The controller (151) is connected to the control terminal and the main throttle port (131) respectively. In the throttle speed control mode, the controller (151) is adapted to control the discharge of the main pump (110) according to the opening of the main throttle port (131) and the flow pressure difference of the overflow valve group (140) until the overflow valve group (140) and the load-sensitive main valve (130) maintain a constant pressure difference respectively. The overflow valve assembly (140) includes: The flow compensation valve (141) has a second pilot port (147), the overflow inlet port and the overflow outlet port; A damping structure is connected to the overflow outlet so that the hydraulic oil coming out of the overflow outlet forms the flow pressure difference, and the outlet of the damping structure is connected to the oil tank (190). The control terminal is connected to the oil inlet and the overflow outlet of the damping structure via an overflow oil passage, so that the flow rate pressure difference acts on the control terminal.

2. The load-sensitive hydraulic control system according to claim 1, characterized in that, The overflow valve assembly (140) also includes a safety valve (145), which is connected in parallel with the damping structure.

3. The load-sensitive hydraulic control system according to claim 1, characterized in that, The overflow valve assembly (140) also includes a throttle valve (143), and the damping structure is disposed within the throttle valve (143).

4. The load-sensitive hydraulic control system according to claim 1, characterized in that, It also includes a one-way valve (153), which is connected to the oil inlet and the overflow outlet of the damping structure through the overflow oil passage, and the flow pressure difference is applied to the control end through the overflow oil passage.

5. The load-sensitive hydraulic control system according to any one of claims 1 to 4, characterized in that, The load-sensitive main valve (130) also includes multiple pressure compensation valves (133) corresponding one-to-one with the multiple actuators (120). The oil outlet of the main throttle port (131) is connected to the corresponding actuator (120) through the corresponding pressure compensation valve (133). A first spring (1331) is provided on one side of the valve core of the pressure compensation valve (133). The relief valve group (140) is provided with a relief valve core. A second spring (1411) is provided on one side of the relief valve core. The load-sensitive hydraulic control system also includes a pressure selection valve (170) suitable for obtaining the highest load pressure. 0) The oil inlet of the actuator (120), the valve core of the pressure compensation valve (133) is set on one side of the first spring (1331), and the overflow valve core is set on one side of the second spring (1411), respectively. The other side of the overflow valve core is adapted to connect to the pressure of the pump outlet, so that the pump outlet pressure after the overflow valve core is balanced forms a constant value between the maximum load pressure and the pressure after the pressure compensation valve (133) is balanced. The other side of the valve core of the pressure compensation valve (133) is connected to the pressure after the main valve of the load-sensitive main valve (130), so that the pressure before and after the load-sensitive main valve (130) after the valve core of the pressure compensation valve (133) is constant.

6. The load-sensitive hydraulic control system according to claim 5, characterized in that, It also includes a control valve (180), which is connected to the pressure compensation valve (133) and the controller (151). In the volumetric speed control mode, the controller (151) is adapted to control the opening of the main throttle (131) to the maximum and control the opening of the pressure compensation valve (133) to the maximum through the control valve (180). The controller (151) also controls the cutting off of the hydraulic oil circuit entering the relief valve assembly (140).

7. The load-sensitive hydraulic control system according to claim 6, characterized in that, It also includes a shut-off valve (160) which is communicatively connected to the controller (151) so that the controller (151) controls the opening or closing of the shut-off valve (160).

8. The load-sensitive hydraulic control system according to claim 5, characterized in that, It also includes a flow control valve, the inlet of which is connected to the outlet of the pump and the inlet of the main throttle port (131), the outlet of which is connected to the outlet of the pressure compensation valve (133), and the flow control valve is connected to the controller (151), which is adapted to control the flow control valve to open to cut off the oil circuit of the hydraulic oil entering the relief valve assembly (140).

9. A load-sensitive hydraulic control method, applied to the load-sensitive hydraulic control system according to any one of claims 1 to 8, characterized in that, include: Obtain the opening degree of the main throttle port (131) and control the discharge of the main pump (110) to be higher than the load demand; Obtain the flow rate and pressure difference of the hydraulic oil after passing through the overflow inlet and overflow outlet of the overflow valve assembly (140); In the throttling speed control mode, the discharge of the main pump (110) is controlled according to the opening degree of the main throttling port (131), and the negative feedback function of the overflow valve group (140) is formed by the flow pressure difference to control the discharge of the main pump (110) until the pressure difference of the overflow valve group (140) and the pressure difference before and after the main throttling port (131) are kept constant, so as to realize the flow distribution function of the load sensitive system.

10. The load-sensitive hydraulic control method according to claim 9, characterized in that, Also includes: The control pressure compensation valve (133) obtains the highest load pressure of multiple actuators, and after the valve core of the pressure compensation valve (133) is balanced, the pressure before and after the load-sensitive main valve (130) is constant. The flow compensation valve is controlled to obtain the maximum load pressure, and after the valve core of the flow compensation valve is balanced, a constant value is formed between the pressure at the pump outlet and the maximum load pressure.

11. The load-sensitive hydraulic control method according to claim 9, characterized in that, It also includes, in volumetric speed regulation mode, controlling the opening of the pressure compensation valve (133) and the opening of the main throttle port (131) to the maximum, and cutting off the oil circuit of the hydraulic oil entering the relief valve group (140).

12. A type of operating machinery, characterized in that, Includes a load-sensitive hydraulic control system as described in any one of claims 1 to 8.

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