CN113653684B - Independent control system for load port with continuously adjustable oil return pressure - Google Patents

Abstract

The invention discloses a load port independent control system with continuously adjustable oil return pressure. The load port independent control system achieves the purposes of adjusting the pressure of a back cavity of an oil return path and self-adapting to flow requirements by adding a pressure-adjustable electric proportional overflow valve on the oil return path and simultaneously connecting a check valve in parallel, thereby solving the problem that a low-pressure cavity of a hydraulic actuator generates cavitation in the traditional load port independent control system in a low-pressure regeneration mode, and simultaneously preventing unnecessary pressure loss caused by overlarge back cavity pressure in the system in a common mode.

Description

Load port independent control system with continuously adjustable oil return pressure

technical field

The invention relates to the technical field of hydraulic transmission and control, in particular to a load port independent control system with continuously adjustable oil return pressure.

Background technique

The independent control system of the load port can break the constraints of coupling adjustment of the inlet and outlet valve ports, so that the system can switch to a hydraulic circuit with better energy consumption according to different working conditions of the actuator, and can increase the control freedom of the system, which can realize the system multi-objective control such as motion control and energy-saving control. When the actuator load exceeds the load, the independent control system of the load port works in the low-pressure regeneration mode, the inlet and outlet of the hydraulic actuator are connected to the low-pressure oil return circuit at the same time, forming a differential connection. At this time, the hydraulic actuator drives the actuator to move through the overrunning load. , without the need for a pump to provide flow. Although the system saves energy in this mode, when the return oil passes through the control valve and enters the low pressure chamber of the hydraulic actuator, it is prone to cavitation through pressure loss along the way and pressure loss at the valve port. At present, in order to solve this problem, a one-way valve is usually added to the oil return circuit to increase the back pressure. The opening pressure of the one-way valve determines the oil return pressure. Although this method solves the problem of cavitation to a certain extent, because the pressure loss increases with the increase of the flow rate, the low-pressure regeneration modes of different flow rates require check valves with different back pressures, so the adaptation of the check valve Poor sex. If a one-way valve with a higher opening pressure is selected to meet different low-pressure regeneration flow requirements, it will cause a larger pressure loss due to the excessively high back cavity pressure of the oil return circuit.

Therefore, in order to solve the problem that cavitation is prone to occur when the system works in the low-pressure regeneration mode, and at the same time avoid the large pressure loss of the system in the normal mode, the present invention proposes a load port independent control system with continuously adjustable oil return pressure. .

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a load port independent control system with continuously adjustable oil return pressure in view of the deficiencies of the prior art.

The object of the present invention is achieved through the following technical solutions: a load port independent control system with continuously adjustable oil return pressure, comprising:

Hydraulic power source to provide the required flow to the system;

The oil tank is used to store the hydraulic oil required by the system;

The controller is used to provide control signals for the system;

The load port independent control valve group is used to change the hydraulic circuit of the system, so that the actuator can work in the required working mode, including the first proportional directional valve, the second proportional directional valve, and the first proportional directional valve, the second proportional directional valve, and the second proportional directional valve. An electric proportional relief valve is added to the oil return circuit between the proportional directional valves and a check valve is connected in parallel to adjust the oil return pressure to avoid cavitation; the set oil return pressure of the electric proportional relief valve is adjusted according to the following formula:

In the formula, q _v2 is the actual flow through the second proportional directional valve, K _v is the flow pressure coefficient of the first proportional directional valve and the second proportional directional valve, and _pr is the difference between the first proportional directional valve and the second proportional directional valve. The oil return circuit pressure between , _pc is the pressure threshold for cavitation.

Hydraulic actuators are used to convert the energy provided by the hydraulic power source into mechanical energy to achieve the actual required operations;

The control handle is used for inputting a speed signal to the controller, and the controller controls the first proportional directional valve and the second proportional directional valve, thereby controlling the action of the hydraulic actuator.

Further, the oil outlet of the hydraulic power source is connected with the oil inlet P of the independent control valve group of the load port through a pipeline, and the oil return port T of the independent control valve group of the load port is connected to the oil tank through a pipeline. connection; the first working oil port A of the load port independent control valve group is connected with the rodless cavity of the hydraulic actuator through a pipeline, and the second working oil port B of the load port independent control valve group is connected with the hydraulic actuator The rod cavities are connected through pipelines; the load port independent control valve group is connected with the controller through an electrical circuit, and the control handle is connected with the controller through an electrical circuit.

Further, the load port independent control valve group includes a first proportional directional valve, a second proportional directional valve, an electric proportional relief valve, a pressure sensor at work port A, a pressure sensor at work port B, and a one-way valve; The proportional directional valve includes an oil inlet port P1, an oil return port T1, and an oil outlet port A1. The second proportional directional valve includes an oil inlet port P2, an oil return port T2, and an oil outlet port A2, wherein the first proportional directional valve The oil inlet P1 of the first proportional directional valve is connected to the oil inlet P2 of the second proportional directional valve and is connected to the oil inlet P of the load port independent control valve group. The oil outlet A1 of the first proportional directional valve and the first working oil port The oil inlet of the pressure sensor of A is connected with the first working oil port A of the load port independent control valve group, the oil outlet A2 of the second proportional directional valve and the inlet of the pressure sensor of the second working oil port B The oil ports are all connected with the second working oil port B of the independent control valve group of the load port. The oil return ports T1 and T2 of the first proportional directional valve and the second proportional directional valve are connected to each other, and are connected to the electric proportional relief valve. The oil outlet of the electric proportional relief valve and the oil inlet of the check valve are connected with the oil return port T of the independent control valve group of the load port.

Further, when the system is in the low-pressure regeneration mode, the two chambers of the hydraulic actuator are connected to the low-pressure oil return circuit at the same time to form a differential connection. At this time, the system will suck oil from the oil tank, and because the oil passes through the pipeline and proportional directional valve, a certain amount of oil will be generated. This pressure loss causes the pressure of the low pressure chamber of the hydraulic actuator to be too low, and then causes the cavitation problem. Therefore, the cavitation can be avoided by adjusting the pressure of the electric proportional relief valve and the parallel check valve on the oil return circuit; when the system is in In the low-compression regeneration mode, the set pressure of the electric proportional relief valve can be adaptively adjusted to match the flow rate of the second proportional directional valve, thereby providing the required oil return back pressure and avoiding the generation of gas in the low-pressure chamber of the hydraulic actuator. When the system is in the low pressure extension regeneration mode, the system needs to draw additional flow from the oil tank or other actuator return oil to meet the flow demand, whether it draws other actuators and returns oil through the relief valve, or through the one-way valve from the oil The oil tank absorbs the flow, which can provide the required flow and ensure a certain return oil circuit pressure to avoid cavitation in the low pressure chamber of the hydraulic actuator; when the system is in the normal working mode, if the pressure in the back chamber is too large, it will cause a large pressure Therefore, the set pressure of the electric proportional relief valve is adjusted to a near zero value, thereby reducing the pressure loss when the oil flows through the electric proportional relief valve and returns to the fuel tank.

Beneficial effects of the present invention:

(1) The present invention increases the oil return pressure in the low-pressure regeneration mode by adding a relief valve in the system oil return circuit to prevent the cavitation problem.

(2) The additional relief valve of the present invention adopts proportional control. When the system is in the low-pressure regeneration mode, it can be adaptively adjusted according to the pressure loss generated by different flow rates; when the system is in the normal mode, the oil return pressure can be reduced to the lowest level. value, so that the pressure loss of the system is reduced, and the energy consumption of the system is reduced.

Description of drawings

Fig. 1 is a system schematic diagram of the independent control system of the load port with continuously adjustable oil return pressure of the present invention.

FIG. 2 is a schematic diagram of the independent control valve group of the load port of the present invention.

Figure 3 is a schematic diagram of the low compression back regeneration mode of the present invention.

Figure 4 is a schematic diagram of the low pressure extension regeneration mode of the present invention.

FIG. 5 is a schematic diagram of the impedance extension mode of the present invention.

Detailed ways

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Referring to FIG. 1, the present invention provides a load port independent control system with continuously adjustable oil return pressure, including:

The hydraulic power source 1 is used to provide the required flow for the system; the oil tank 2 is used to store the hydraulic oil required by the system; the controller 3 is used to provide control signals for the system; the hydraulic actuator 5. It is used to convert the energy provided by the hydraulic power source 1 into mechanical energy to realize the actual required operations, such as the lifting motion of the excavator mechanical arm; the control handle 6 is used to input the speed signal to the controller 3, through the controller 3. Control the first proportional directional valve 41 and the second proportional directional valve 42, and then control the action of the hydraulic actuator 5.

The load port independently controls the valve group 4, which is used to change the hydraulic circuit of the system, so that the actuator can work in the required working mode, including the first proportional directional valve 41, the second proportional directional valve 42, and the first proportional directional valve 42. An electric proportional relief valve 43 is added on the oil return circuit between the directional valve 41 and the second proportional directional valve 42, and a check valve 44 is connected in parallel to adjust the oil return pressure to avoid cavitation;

The oil outlet of the hydraulic power source 1 is connected with the oil inlet P of the load port independent control valve group 4 through a pipeline, and the oil return port T of the load port independent control valve group 4 and the oil tank 2 are connected through a pipeline The first working oil port A of the load port independent control valve group 4 is connected with the rodless cavity of the hydraulic actuator 5 through a pipeline, and the load port independently controls the second working oil port B of the valve group 4 It is connected with the rod cavity of the hydraulic actuator 5 through a pipeline; the independent control valve group 4 of the load port is connected with the controller 3 through an electrical circuit, and the control handle 6 is communicated with the controller 3 through an electrical circuit.

2, the load port independent control valve group 4 includes a first proportional directional valve 41, a second proportional directional valve 42, an electric proportional relief valve 43, a pressure sensor 44 of the first working oil port A, and a second working oil Pressure sensor 45 at port B. The first proportional directional valve 41 includes an oil inlet P1, an oil return port T1, and an oil outlet A1, and the second proportional directional valve 42 includes an oil inlet P2, an oil return port T2, and an oil outlet A2, wherein the The oil inlet P1 of the first proportional directional valve 41 is connected to the oil inlet P2 of the second proportional directional valve 42 and is connected to the oil inlet P of the load port independent control valve group 4. The first proportional directional valve 41 The oil outlet A1 and the oil inlet of the pressure sensor 44 of the first working oil port A are both connected to the first working oil port A of the load port independent control valve group 4, and the oil outlet of the second proportional directional valve 42 The oil inlets of the pressure sensor 45 of A2 and the second working oil port B are both connected to the second working oil port B of the load port independent control valve group 4. The first proportional directional valve 41 and the second proportional directional valve 42 The oil return ports T1 and T2 of the electric proportional relief valve 43 are connected with each other, and are connected with the oil outlet of the electric proportional relief valve 43 and the oil outlet of the check valve 44. The oil inlet of the electric proportional relief valve 43 and the check valve 44 inlet oil The port is connected to the oil return port T of the independent control valve group 4 of the load port.

The load port independent control system with continuously adjustable oil return pressure includes seven working modes. In normal mode, the system can work in four modes: impedance extension, impedance retraction, overshoot extension, and overshoot retraction; in regeneration mode, the system can work in high voltage extension regeneration, low compression regeneration regeneration, and low extension regeneration. out of three modes of regeneration.

The embodiments of the present invention take the low compression back regeneration and low pressure extension regeneration modes as examples; when the system is in the normal mode, the impedance extension mode is used as an example, and other normal working modes are similar.

Referring to FIG. 3 , the first proportional directional valve 41 and the second proportional directional valve 42 of the load port independent control valve group 4 are both energized in the right position, and the rodless cavity and the rod cavity of the hydraulic actuator 5 are connected to the low-pressure oil return circuit at the same time. , the hydraulic actuator 5 is driven by the overload to retract the piston rod. At this time, the oil flows from the rodless cavity of the hydraulic actuator to the rod cavity by the pressure generated by the load acting on the actuator, without the need for the pump to provide additional flow. At this time, the set pressure of the electric proportional relief valve 43 is adaptively adjusted following the flow rate through the second proportional directional valve 42 to avoid cavitation in the rod cavity of the hydraulic actuator 5 . The set return oil pressure of the electric proportional relief valve 43 is adjusted according to the following formula:

In the formula, q _v2 is the actual flow through the second proportional directional valve 42, K _v is the flow pressure coefficient of the first proportional directional valve 41 and the second proportional directional valve 42, and _pr is the first proportional directional valve 41 and the second proportional directional valve 41 and the second Return oil circuit pressure between proportional directional valve 42, _pc is the pressure threshold for cavitation

Referring to Figure 4, the first proportional directional valve 41 and the second proportional directional valve 42 of the load port independent control valve group 4 are both energized to the right, and the rodless cavity and the rod cavity of the hydraulic actuator 5 are connected to the low-pressure oil return circuit at the same time. , the hydraulic actuator 5 is driven beyond the load to extend the piston rod. At this time, the pressure generated by the load acting on the actuator flows from the rod cavity to the rodless cavity of the hydraulic actuator. There is no need for a pump to provide flow, but the system still needs to obtain a certain amount of pressure. of additional traffic. If the system is a multi-actuator system, the additional flow required can be drawn from the oil return of other actuators and returned to the oil through the electric proportional relief valve 43. At this time, the set pressure of the electric proportional relief valve 43 follows through the first The size of the flow of a proportional directional valve 41 is adaptively adjusted; if the system is a single-actuator system, oil is drawn from the oil tank through the one-way valve 44 to meet the required flow. No matter sucking other actuators and returning the oil through the electric proportional relief valve 43, or sucking the flow from the oil tank through the one-way valve 44, the required flow can be provided and a certain return oil circuit pressure can be guaranteed to avoid the rodless hydraulic actuator 5. Cavities create air pockets.

Referring to Figure 5, the first proportional directional valve 41 of the load port independent control valve group 4 is energized to the left, the second proportional directional valve 42 is energized to the right, and the rodless cavity of the hydraulic actuator 5 is connected to the high-pressure oil of the pump, with a rod The cavity is connected to the low-pressure oil return circuit, and the piston rod of the hydraulic actuator 5 extends to push the load. At this time, the electric proportional relief valve 43 adjusts the set pressure to a value close to zero, so as to reduce the pressure loss when the oil returns to the oil tank.

The above-mentioned embodiments are used to explain the present invention, rather than limit the present invention. Within the spirit of the present invention and the protection scope of the claims, any modifications and changes made to the present invention all fall into the protection scope of the present invention.

Claims (4)

1. The utility model provides a return oil pressure continuously adjustable's load mouth independent control system which characterized in that includes:

the hydraulic power source (1) is used for providing required flow for the system;

the oil tank (2) is used for storing hydraulic oil required by the system;

a controller (3) for providing control signals to the system;

the load port independent control valve group (4) is used for changing a hydraulic circuit of a system to enable an actuator to work in a required working mode, comprises a first proportional direction valve (41) and a second proportional direction valve (42), and is characterized in that an electric proportional overflow valve (43) is additionally arranged on an oil return path between the first proportional direction valve (41) and the second proportional direction valve (42) and is connected with a one-way valve (44) in parallel at the same time, and the oil return pressure is adjusted to avoid cavitation; the set oil return pressure of the electric proportional overflow valve (43) is adjusted according to the following formula:

in the formula (I), the compound is shown in the specification,

for the actual flow through the second proportional directional valve (42),

is the flow pressure coefficient of the first proportional directional valve (41) and the second proportional directional valve (42),

is the return pressure between the first proportional directional valve (41) and the second proportional directional valve (42),

a pressure threshold for cavitation;

the hydraulic actuator (5) is used for converting the energy provided by the hydraulic power source (1) into mechanical energy to realize the operation required actually;

the control handle (6) is used for inputting a speed signal to the controller (3), and the controller (3) is used for controlling the first proportional directional valve (41) and the second proportional directional valve (42) so as to control the action of the hydraulic actuator (5).

2. The load port independent control system with continuously adjustable oil return pressure as claimed in claim 1, characterized in that an oil outlet of the hydraulic power source (1) and an oil inlet P of the load port independent control valve group (4) are connected through a pipeline, and an oil return port T of the load port independent control valve group (4) and the oil tank (2) are connected through a pipeline; a first working oil port A of the load port independent control valve group (4) is connected with a rodless cavity of the hydraulic actuator (5) through a pipeline, and a second working oil port B of the load port independent control valve group (4) is connected with a rod cavity of the hydraulic actuator (5) through a pipeline; the load port independent control valve group (4) is connected with the controller (3) through an electric circuit, and the control handle (6) is communicated with the controller (3) through the electric circuit.

3. The load port independent control system with the continuously adjustable oil return pressure as claimed in claim 2, wherein the load port independent control valve group (4) comprises a first proportional directional valve (41), a second proportional directional valve (42), an electric proportional overflow valve (43), a pressure sensor (46) of a first working oil port A, a pressure sensor (45) of a second working oil port B and a check valve (44); the first proportional directional valve (41) comprises an oil inlet P1, an oil return port T1 and an oil outlet A1, the second proportional directional valve (42) comprises an oil inlet P2, an oil return port T2 and an oil outlet A2, wherein an oil inlet P1 of the first proportional directional valve (41) is connected with an oil inlet P2 of the second proportional directional valve (42) and is connected with an oil inlet P of the load port independent control valve group (4), the oil outlet A1 of the first proportional directional valve (41) and the oil inlets of pressure sensors (46) of a first working oil port A are connected with a first working oil port A of the load port independent control valve group (4), the oil outlet A2 of the second proportional directional valve (42) and the oil inlets of pressure sensors (45) of a second working oil port B are connected with a second working oil port B of the load port independent control valve group (4), and the oil return ports T54 of the first proportional directional valve (41) and the second proportional directional valve (42) are connected with a working oil return port T1 of the load port independent control valve group (4), T2 are connected with each other and are connected with the oil outlet of the electric proportional overflow valve (43) and the oil outlet of the check valve (44), and the oil inlet of the electric proportional overflow valve (43) and the oil inlet of the check valve (44) are connected with the oil return port T of the load port independent control valve group (4).

4. The load port independent control system with the continuously adjustable return oil pressure as claimed in any one of claims 1-3, characterized in that when the system is in a low-pressure regeneration mode, two cavities of the hydraulic actuator (5) are simultaneously communicated with a low-pressure return oil circuit to form a differential connection, and the system can suck oil from the oil tank (2) at the moment, and air cavities are avoided by adjusting the pressure of an electric proportional overflow valve (43) on the return oil circuit and a parallel one-way valve (44); when the system is in a low-pressure retraction regeneration mode, the set pressure of the electric proportional overflow valve (43) can be matched with the flow of the second proportional directional valve (42) for self-adaptive adjustment, so that required oil return back pressure is provided, and cavitation of a low-pressure cavity of the hydraulic actuator (5) is avoided; when the system is in a low-pressure extension regeneration mode, the system needs to absorb extra flow from oil return of an oil tank (2) or other actuators to meet the flow demand, and the system can provide required flow and ensure certain pressure of an oil return path no matter absorbs other actuators and returns oil through an overflow valve or absorbs flow from the oil tank through a one-way valve (44), so that cavitation of a low-pressure cavity of a hydraulic actuator (5) is avoided; when the system is in a common working mode, the set pressure of the electric proportional overflow valve (43) is adjusted to be nearly zero, so that the pressure loss of oil when the oil returns to the oil tank (2) through the electric proportional overflow valve (43) is reduced.

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