CN115681231A

CN115681231A - Hydraulic control system and control method thereof

Info

Publication number: CN115681231A
Application number: CN202211295801.6A
Authority: CN
Inventors: 张云威; 尹超; 崔广伟; 张俊; 李会超
Original assignee: Xuzhou XCMG Excavator Machinery Co Ltd
Current assignee: Xuzhou XCMG Excavator Machinery Co Ltd
Priority date: 2022-10-21
Filing date: 2022-10-21
Publication date: 2023-02-03

Abstract

The invention relates to the technical field of hydraulic control of engineering machinery, and discloses a hydraulic control system and a control method thereof, wherein the hydraulic control system comprises a movable arm oil cylinder, a bucket rod oil cylinder, a bucket oil cylinder, a movable arm reversing valve, a bucket rod reversing valve, a bucket reversing valve, a sensor, an electromagnetic valve and a controller; the controller is respectively and electrically connected with two control ends of the movable arm reversing valve, the bucket rod reversing valve and the bucket reversing valve, the controller is electrically connected with the control end of the electromagnetic valve, and the controller is in communication connection with the sensor; the sensor is connected with the movable arm oil cylinder and used for collecting pressure of a large cavity and a small cavity of the movable arm oil cylinder and displacement signals of a piston rod of the movable arm oil cylinder; an oil inlet of the electromagnetic valve is connected with a small cavity of the movable arm oil cylinder, and an oil outlet of the electromagnetic valve is connected with a large cavity of the movable arm oil cylinder. The invention has the beneficial effects that: when the excavator is used for flat ground and excavation operation, the front end of the excavator can be prevented from tilting, the stability of the whole excavator is kept, and the operation comfort is improved.

Description

Hydraulic control system and control method thereof

Technical Field

The invention relates to the technical field of engineering machinery, in particular to a hydraulic control system and a control method thereof for an excavator.

Background

In the existing excavator, port overflow valves are arranged in the large cavity and the small cavity of a movable arm, the set value is a fixed value and is slightly higher than the set pressure of a system, and under the overflow pressure, when excavating or heavy-load flat land operation is carried out, the movable arm generally has no action and only depends on the combined operation of a bucket and a bucket rod to carry out the operation; at this time, when digging or heavy load flat ground retraction operation is carried out, the bucket meets large resistance, and reaction force is transmitted to the movable arm; because the overflow pressure of the port of the movable arm oil cylinder is high, the movable arm oil cylinder can bear large reaction force, and under the reaction force, the front end of the excavator is tilted and slightly leaves the ground, so that the whole excavator shakes, and the operation comfort is influenced; the force is shown in figure 1, and the front end of the excavator is tilted as shown in figure 2.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a hydraulic control system and a control method thereof, which can prevent the front end of an excavator from tilting when the excavator works on the ground and excavates, keep the whole excavator stable and improve the operation comfort.

In order to achieve the purpose, the invention provides the following technical scheme:

in a first aspect, the invention provides a hydraulic control system, which comprises a movable arm oil cylinder, an arm oil cylinder, a bucket oil cylinder, a movable arm reversing valve, an arm reversing valve, a bucket reversing valve, a sensor, an electromagnetic valve and a controller, wherein the movable arm oil cylinder is connected with the arm oil cylinder; the movable arm oil cylinder is connected with the movable arm reversing valve, the bucket rod oil cylinder is connected with the bucket rod reversing valve, and the bucket oil cylinder is connected with the bucket reversing valve; the controller is respectively and electrically connected with two control ends of the movable arm reversing valve, the bucket rod reversing valve and the bucket reversing valve, the controller is electrically connected with a control end of the electromagnetic valve, and the controller is in communication connection with the sensor; the sensor is connected with the movable arm oil cylinder and used for acquiring the pressure of a large cavity and a small cavity of the movable arm oil cylinder and displacement signals of a piston rod of the movable arm oil cylinder and transmitting the pressure data and the displacement signals to the controller; an oil inlet of the electromagnetic valve is connected with a small cavity of the movable arm oil cylinder, an oil outlet of the electromagnetic valve is connected with a large cavity of the movable arm oil cylinder, the electromagnetic valve comprises a normally closed working position and a conducting working position, when excavation and land leveling operation are carried out, the movable arm reversing valve has no pilot pressure or pilot signals, and under the condition that the bucket reversing valve and the bucket rod reversing valve have pilot pressure or pilot signals, if the load is greater than the preset load, the controller sends a signal for switching to the conducting working position to the electromagnetic valve; the controller is also used for sending a signal for replacing the working position to the electromagnetic valve, the movable arm reversing valve, the bucket rod reversing valve and the bucket reversing valve according to the pressure data and the displacement signal acquired by the sensor and the operation signal of an operator.

In combination with the first aspect, further, the hydraulic system of the present invention further includes a hydraulic oil tank and a main pump, an oil outlet of the main pump is respectively connected to an oil inlet C1 of the boom directional control valve, an oil inlet C2 of the bucket rod directional control valve, and an oil inlet C3 of the bucket directional control valve, an oil outlet A1 of the boom directional control valve is connected to a large cavity of the boom cylinder, a small cavity of the boom cylinder is connected to an oil return port B1 of the boom directional control valve, and an oil outlet D1 of the boom directional control valve is connected to the hydraulic oil tank; an oil outlet A2 of the bucket rod reversing valve is connected with a small cavity of the bucket rod oil cylinder, a large cavity of the bucket rod oil cylinder is connected with an oil return port B2 of the bucket rod reversing valve, and an oil outlet D2 of the bucket rod reversing valve is connected with a hydraulic oil tank; an oil outlet A3 of the bucket reversing valve is connected with a small cavity of the bucket oil cylinder, a large cavity of the bucket oil cylinder is connected with an oil return port B3 of the bucket reversing valve, and an oil outlet D3 of the bucket reversing valve is connected with a hydraulic oil tank.

With reference to the first aspect, the hydraulic system further includes an overflow valve, an oil inlet of the overflow valve is connected to an oil outlet of the main pump, an oil outlet of the overflow valve is connected to the hydraulic oil tank, and the overflow valve is configured to set system pressure and protect hydraulic elements such as the main pump.

Meanwhile, a plurality of port overflow valves are further arranged in the hydraulic system, and are respectively arranged between the movable arm oil cylinder and the port A1 of the movable arm reversing valve, between the movable arm oil cylinder and the port B1 of the movable arm reversing valve, between the arm oil cylinder and the port A2 of the arm reversing valve, between the arm oil cylinder and the port B2 of the arm reversing valve, between the bucket oil cylinder and the port A3 of the bucket reversing valve, and between the bucket oil cylinder and the port B3 of the bucket reversing valve. The port overflow valve is arranged for protecting the movable arm oil cylinder, the bucket rod oil cylinder and the bucket oil cylinder.

With reference to the first aspect, further, the hydraulic system of the present invention further includes a check valve set, an oil inlet of the check valve set is connected to the hydraulic oil tank, and an oil outlet of the check valve set is connected to an oil inlet E of the boom directional control valve; the check valve group is used for preventing the large cavity of the movable arm oil cylinder from being sucked to be empty, and after the oil way of the large cavity and the oil way of the small cavity of the movable arm oil cylinder are communicated, the large cavity of the movable arm oil cylinder supplies oil, and on the one hand, the small cavity hydraulic oil flows into the large cavity through the electromagnetic valve to supply oil; on one hand, the oil is supplemented to the large cavity from the hydraulic oil tank through the oil way where the check valve group is located.

With reference to the first aspect, further, the bucket rod reversing valve at least includes 3 working positions, and the 3 working positions are a left working position, a middle working position and a right working position from left to right in sequence; all 6 ports of the working position in the bucket rod reversing valve are not communicated with each other; the oil port C2 of the left working position is communicated with the oil port A2, and the oil port B2 is communicated with the oil port D2; and the oil port C2 of the right working position is communicated with the oil port B2, and the oil port A2 is communicated with the oil port D2. When the valve core of the bucket rod reversing valve is positioned at the left working position and the right working position, the bucket rod oil cylinder does telescopic motion at the moment, namely the bucket rod does inward-contraction outward-swinging operation, namely the bucket rod of the excavator is in a working state.

With reference to the first aspect, further, the bucket reversing valve at least includes 3 working positions, and the 3 working positions are a left working position, a middle working position and a right working position from left to right in sequence; no 6 ports of the working position in the bucket reversing valve are communicated with each other; the oil port C3 of the left working position is communicated with the oil port A3, and the oil port B3 is communicated with the oil port D3; and an oil port C3 of the right working position is communicated with an oil port B3, and an oil port A3 is communicated with an oil port D3. When the valve core of the bucket reversing valve is positioned at the left working position and the right working position, the bucket oil cylinder does telescopic motion at the moment, namely the bucket rod does inward-contraction outward-swinging operation, namely the excavator bucket is in a working state.

Preferably, the bucket rod reversing valve is a three-position six-way electromagnetic reversing valve; the bucket reversing valve is a three-position six-way electromagnetic reversing valve.

With reference to the first aspect, further, the movable arm directional control valve at least includes 3 working positions, and the 3 working positions are a left working position, a middle working position and a right working position from left to right in sequence; an oil port A1 and an oil port E of a working position in the movable arm reversing valve are communicated, and the rest oil ports are not communicated with each other; the oil port C1 of the left working position is communicated with the oil port A1, and the oil port B1 is communicated with the oil port D1; the oil port C1 of the right working position is communicated with the oil port B1, and the oil port A1 is communicated with the oil port D1. After the tilting prevention operation, the movable arm rises due to the rising of a piston rod of the movable arm oil cylinder, and the position of the movable arm needs to be further compensated for maintaining the operation posture; the controller controls the reversing valve of the movable arm to be in a right working position, at the moment, the main pump enables pressure oil to enter a small cavity of the movable arm oil cylinder, and the piston rod moves downwards until the piston rod reaches a position before the tilting prevention.

Preferably, the movable arm reversing valve is a three-position six-way electromagnetic reversing valve.

With reference to the first aspect, further, the solenoid valve is a two-position two-way solenoid valve, two oil ports of the upper working position are not communicated with each other, and the solenoid valve is a normally closed working position; two oil ports of the lower working position are communicated, namely the working position is conducted.

With reference to the first aspect, further, the sensor includes a pressure sensor and a displacement sensor, and the pressure sensor is respectively connected to the controller and the large cavity and the small cavity of the boom cylinder, and is configured to collect pressures of the large cavity and the small cavity of the boom cylinder and transmit pressure data to the controller; the displacement sensor is arranged on a piston rod of the movable arm oil cylinder and used for collecting displacement data of the piston rod of the movable arm oil cylinder and transmitting the displacement data to the controller.

With reference to the first aspect, further, the boom cylinder may be a single cylinder or a dual cylinder.

In a second aspect, the present invention provides a method for controlling a hydraulic control system, based on the above hydraulic control system, including the following steps:

excavating or leveling work;

the sensor collects the pressure P1 of a large cavity of the movable arm oil cylinder and the pressure P2 of a small cavity of the movable arm oil cylinder in real time and transmits collected pressure data to the controller;

when the movable arm reversing valve has no pilot pressure or pilot signals and the bucket reversing valve and the arm reversing valve have pilot pressure or pilot signals, the controller compares pressure data from the sensor with excavator tilting pressure Pm preset in the controller;

if the load is too large, namely the pressure P2 of a small cavity of the movable arm oil cylinder is greater than the tilting pressure Pm of the excavator preset in the controller, the controller sends a control signal to the electromagnetic valve to enable a valve core of the electromagnetic valve to move upwards, the electromagnetic valve is located at a conduction working position, at the moment, an oil way of the large cavity and the small cavity of the movable arm oil cylinder is communicated, pressure oil of the small cavity flows to the large cavity, and the pressure of the small cavity is reduced;

when the small cavity pressure P2 is reduced to be smaller than the excavator tilting pressure Pm preset in the controller, the controller sends a control signal to the electromagnetic valve, so that the valve core of the electromagnetic valve moves downwards, the electromagnetic valve is in a normally closed working position, and at the moment, the oil passages of the large cavity and the small cavity of the movable arm oil cylinder are closed.

It should be noted that: the tilting pressure Pm of the excavator preset in the controller is a design parameter of the excavator, and refers to the minimum movable arm small cavity pressure value which can cause the excavator to tilt and influence the feeling of an operator when only the arm cylinder and the bucket cylinder are operated.

In combination with the second aspect, further, the control method of the present invention further includes the step of acquiring, by the sensor, a displacement value of the piston rod of the boom cylinder relative to the cylinder barrel in real time, and transmitting the displacement value L to the controller.

With reference to the second aspect, further, the control method of the present invention further includes a boom position compensation method, specifically:

when the controller detects that the excavator works on the flat ground, the controller does not receive a boom cylinder operation signal of a driver, the controller sends a control signal for switching to a conducting working position to the electromagnetic valve, and the controller receives the displacement of a boom cylinder piston collected by the sensor, the position of a boom needs to be compensated, and the specific compensation method comprises the following steps:

the controller sends a control signal to a control end of the movable arm reversing valve, so that the movable arm reversing valve is switched to a right working position, at the moment, a small cavity of the movable arm oil cylinder obtains oil, and a piston rod of the movable arm oil cylinder moves downwards;

the controller calculates the difference between a real-time displacement value L3 of the piston rod of the movable arm oil cylinder and a displacement value L1 of the movable arm piston rod before the electromagnetic valve is switched to the conducting working position every delta t time to obtain a difference delta L1;

when the absolute value of the delta l1 falls within the range of the set value [ delta l-n, delta l + n ], the controller sends a control signal to the movable arm reversing valve, so that the movable arm reversing valve is switched to the middle working position to keep the position of the movable arm oil cylinder at the moment.

In the set value, delta L is an absolute value of a displacement difference obtained by calculating the difference between a displacement value L1 of a piston rod of the movable arm oil cylinder before the received electromagnetic valve is switched to a conducting working position and a displacement value L2 of the piston rod of the movable arm oil cylinder after the electromagnetic valve is switched to a normally closed working position by the controller; in the set values, n is one of excavator design parameters (n is a revised value of the displacement difference value of the oil cylinder of the excavator with different tonnages, the attitude of the excavator does not influence normal operation within an error range), and if delta l1 is within a range of [ delta l-n, delta l + n ], the displacement of the piston rod of the movable arm oil cylinder does not influence the position compensation of the flat ground operation.

With reference to the second aspect, further, the boom position compensation action occurs after Δ k time after the solenoid valve is switched to the normally closed working position, where Δ k is a set value according to a common working speed of different tonnages.

Compared with the prior art, the invention provides a hydraulic control system and a control method thereof, which have the following beneficial effects:

(1) According to the hydraulic control system, due to the arrangement of the electromagnetic valve and the sensor, the reaction force transmitted to the small cavity of the movable arm oil cylinder during operation can be released during flat ground and excavation operation, the front end of the excavator is prevented from tilting, the stability of the whole excavator is kept, and the operation comfort is improved.

(2) The hydraulic control system can realize the compensation of the position of the movable arm under the flat ground, and a driver does not need to adjust the operation posture of the movable arm again, thereby reducing the fatigue strength of operators and improving the operation efficiency.

Drawings

FIG. 1 is a schematic diagram of the prior art excavator's force during digging or heavy-duty retracting in flat ground operation;

FIG. 2 is a schematic view of the prior art excavator with its front end tilted during digging or heavy-duty flat ground retraction operation;

fig. 3 is a hydraulic schematic diagram of the hydraulic system of the present invention (in the drawing, the boom cylinder is a double cylinder).

The reference numerals in the figures have the meaning:

1-main pump; 2-a controller; 3-a movable arm reversing valve; 4-an electromagnetic valve; 5-a boom cylinder; 6-a sensor; 7-a bucket rod oil cylinder; 8-a bucket rod reversing valve; 9-a bucket cylinder; 10-a bucket change valve; 11-a hydraulic oil tank; 12-a one-way valve set; 13-relief valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may also include different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be discussed further in subsequent figures.

In the description of the present application, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for the convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the claimed invention.

As shown in fig. 3, the hydraulic system provided by the present invention includes a boom cylinder 5, an arm cylinder 7, a bucket cylinder 9, a boom directional control valve 3, an arm directional control valve 8, a bucket directional control valve 10, a sensor 6, an electromagnetic valve 4, and a controller 2; the movable arm oil cylinder 5 is connected with the movable arm reversing valve 3, the bucket rod oil cylinder 7 is connected with the bucket rod reversing valve 8, and the bucket oil cylinder 9 is connected with the bucket reversing valve 10; the controller 2 is respectively electrically connected with two control ends of the movable arm reversing valve 3, the bucket rod reversing valve 8 and the bucket reversing valve 10, the controller 2 is electrically connected with a control end of the electromagnetic valve 4, and the controller 2 is in communication connection with the sensor 6; the sensor 6 is connected with the movable arm oil cylinder 5 and used for collecting the pressure of a large cavity and a small cavity of the movable arm oil cylinder 5 and a displacement signal of a piston rod of the movable arm oil cylinder 5 and transmitting the pressure data and the displacement signal to the controller 2; an oil inlet of the electromagnetic valve 4 is connected with a small cavity of the movable arm oil cylinder 5, an oil outlet of the electromagnetic valve 4 is connected with a large cavity of the movable arm oil cylinder 5, the electromagnetic valve 4 comprises a normally closed working position and a conducting working position, when excavation and land leveling work are carried out, the movable arm reversing valve 3 has no pilot pressure or pilot signal, and under the condition that the bucket reversing valve 10 and the bucket rod reversing valve 8 have the pilot pressure or pilot signal, if the load is greater than the preset load, the controller 2 sends a signal for switching to the conducting working position to the electromagnetic valve 4; the controller 2 is further configured to send signals of the replacement work positions to the electromagnetic valve 4, the boom directional control valve 3, the arm directional control valve 8, and the bucket directional control valve 10 according to the pressure data and the displacement signals acquired by the sensor 6 and the operation signals of the operator.

In a specific implementation manner of this embodiment, the hydraulic system of the present invention further includes a hydraulic oil tank 11 and a main pump 1, an oil outlet of the main pump 1 is respectively connected to an oil inlet C1 of the movable arm directional control valve 3, an oil inlet C2 of the bucket rod directional control valve 8, and an oil inlet C3 of the bucket directional control valve 10, an oil outlet A1 of the movable arm directional control valve 3 is connected to a large cavity of the movable arm oil cylinder 5, a small cavity of the movable arm oil cylinder 5 is connected to an oil return port B1 of the movable arm directional control valve 3, and an oil outlet D1 of the movable arm directional control valve 3 is connected to the hydraulic oil tank 11; an oil outlet A2 of the bucket rod reversing valve 8 is connected with a small cavity of the bucket rod oil cylinder 7, a large cavity of the bucket rod oil cylinder 7 is connected with an oil return port B2 of the bucket rod reversing valve 8, and an oil outlet D2 of the bucket rod reversing valve 8 is connected with a hydraulic oil tank 11; an oil outlet A3 of the bucket reversing valve 10 is connected with a small cavity of the bucket oil cylinder 9, a large cavity of the bucket oil cylinder 9 is connected with an oil return port B3 of the bucket reversing valve 10, and an oil outlet D3 of the bucket reversing valve 10 is connected with a hydraulic oil tank 11.

In a specific implementation manner of this embodiment, the hydraulic system of the present invention further includes an overflow valve 13, an oil inlet of the overflow valve 13 is connected to an oil outlet of the main pump 1, an oil outlet of the overflow valve 13 is connected to the hydraulic oil tank 11, and the overflow valve 13 sets a system pressure to protect hydraulic elements such as the main pump.

Meanwhile, a plurality of port overflow valves are further arranged in the hydraulic system, and are respectively arranged between the movable arm cylinder 5 and the port A1 of the movable arm directional control valve 3, between the movable arm cylinder 5 and the port B1 of the movable arm directional control valve 3, between the arm cylinder 7 and the port A2 of the arm directional control valve 8, between the arm cylinder 7 and the port B2 of the arm directional control valve 8, between the bucket cylinder 9 and the port A3 of the bucket directional control valve 10, and between the bucket cylinder 9 and the port B3 of the bucket directional control valve 10. The port overflow valves are arranged to protect the boom cylinder 5, the arm cylinder 7, and the bucket cylinder 9.

In a specific embodiment of the present embodiment, the hydraulic system further includes a check valve group 12, an oil inlet of the check valve group 12 is connected to the hydraulic oil tank 11, an oil outlet of the check valve group 12 is connected to an oil inlet E of the boom directional control valve 3, the check valve group 12 is configured to prevent a large cavity of the boom oil cylinder 5 from being empty, and when a large cavity oil path of the boom oil cylinder 5 is communicated, the large cavity oil supplement of the boom oil cylinder 5 flows the small cavity hydraulic oil into the large cavity through the electromagnetic valve 4 to supplement oil; on the one hand, the oil is supplemented to the large cavity from the hydraulic oil tank 11 through the oil way where the check valve group 12 is located.

The use principle of the check valve group 12 in the hydraulic system is as follows: when the tilting prevention operation is performed, the electromagnetic valve 4 is in a conduction working position, pressure oil in a small cavity of the movable arm oil cylinder 5 enters a large cavity, and at the moment, a piston of the movable arm oil cylinder 5 moves upwards; because the action area of the large cavity of the oil cylinder is larger than that of the small cavity, when the quantity of pressure oil flowing into the large cavity from the small cavity is not enough to support the oil cylinder to move to a corresponding position, oil needs to be supplemented from the hydraulic oil tank 11; the check valve group 12 comprises a check valve and a throttle valve (actually, an orifice), and the existence of the orifice can limit the oil supplementing speed from the hydraulic oil tank 11, so that the movement speed is prevented from being too high when the movable arm oil cylinder 5 is subjected to the tilting prevention operation; the check valve can allow the movable arm large cavity to supplement oil from the hydraulic oil tank on one hand, and prevents the arm from falling when the excavator works on the other hand, so that the function of keeping the valve is achieved.

In a specific implementation manner of this embodiment, the arm reversing valve 8 at least includes 3 working positions, and the 3 working positions are a left working position, a middle working position, and a right working position in sequence from left to right; 6 ports of the working position in the bucket rod reversing valve 8 are not communicated with each other; the oil port C2 of the left working position is communicated with the oil port A2, and the oil port B2 is communicated with the oil port D2; and the oil port C2 of the right working position is communicated with the oil port B2, and the oil port A2 is communicated with the oil port D2. When the valve core of the bucket rod reversing valve 8 is in the left and right working positions, the bucket rod oil cylinder 7 does telescopic motion at the moment, namely, the bucket rod does inward-contraction outward-swinging operation, namely, the bucket rod of the excavator is in a working state.

In a specific implementation manner of this embodiment, the bucket reversing valve 10 at least includes 3 working positions, and the 3 working positions are a left working position, a middle working position, and a right working position in sequence from left to right; no 6 ports of the working position in the bucket reversing valve 10 are communicated with each other; the oil port C3 of the left working position is communicated with the oil port A3, and the oil port B3 is communicated with the oil port D3; and an oil port C3 of the right working position is communicated with an oil port B3, and an oil port A3 is communicated with an oil port D3. When the valve core of the bucket reversing valve 10 is at the left and right working positions, the bucket cylinder 9 makes telescopic motion, namely the arm makes inward-retracting and outward-swinging operation, namely the excavator bucket is in a working state.

Preferably, the bucket rod reversing valve 8 is a three-position six-way electromagnetic reversing valve; the bucket directional valve 10 is a three-position six-way electromagnetic directional valve.

In a specific implementation manner of this embodiment, the movable arm directional control valve 3 at least includes 3 working positions, and the 3 working positions are a left working position, a middle working position, and a right working position in sequence from left to right; an oil port A1 and an oil port E of a working position in the movable arm reversing valve 3 are communicated, and the rest oil ports are not communicated; the oil port C1 of the left working position is communicated with the oil port A1, and the oil port B1 is communicated with the oil port D1; the oil port C1 of the right working position is communicated with the oil port B1, and the oil port A1 is communicated with the oil port D1. After the tilting prevention operation, the boom is lifted due to the lifting of the piston rod of the boom cylinder 5, and in order to maintain the working posture, the position of the boom needs to be further compensated; the controller 2 controls the boom reversing valve 3 to be in a right working position, at the moment, the main pump 1 enables pressure oil to enter a small cavity of the boom cylinder 5, and the piston rod moves downwards until the piston rod reaches a position before tilting prevention.

Preferably, the movable arm reversing valve 3 is a three-position six-way electromagnetic reversing valve.

In a specific embodiment of this embodiment, the solenoid valve 4 is a two-position two-way solenoid valve 4, two oil ports of the upper working position are not communicated, and the upper working position is normally closed; and two oil ports of the lower working position are communicated, namely the working position is conducted.

In a specific implementation manner of this embodiment, the sensor 6 includes a pressure sensor and a displacement sensor, and the pressure sensor is connected to the controller 2 and the large cavity and the small cavity of the boom cylinder 5, and is configured to collect pressures of the large cavity and the small cavity of the boom cylinder 5 and transmit pressure data to the controller 2; the displacement sensor is arranged on a piston rod of the movable arm cylinder 5 and used for collecting displacement data of the piston rod of the movable arm cylinder 5 and transmitting the displacement data to the controller 2.

In a specific embodiment of the present embodiment, the boom cylinder 5 may be a single cylinder or a dual cylinder.

The invention also provides a control method of the hydraulic control system, which is based on the hydraulic system and comprises the following steps:

excavating or leveling work;

the sensor 6 collects the pressure P1 of the large cavity of the movable arm oil cylinder 5 and the pressure P2 of the small cavity of the movable arm oil cylinder 5 in real time and transmits the collected pressure data to the controller 2;

when the boom directional control valve 3 has no pilot pressure or pilot signal and the bucket directional control valve 10 and the arm directional control valve 8 have pilot pressure or pilot signal, the controller 2 compares the pressure data from the sensor 6 with the excavator tilting pressure Pm preset in the controller 2;

if the load is too large, namely the pressure P2 of the small cavity of the movable arm oil cylinder 5 is greater than the tilting pressure Pm of the excavator preset in the controller 2, the controller 2 sends a control signal to the electromagnetic valve 4, so that the valve core of the electromagnetic valve 4 moves upwards, the electromagnetic valve 4 is in a conduction working position, at the moment, the oil circuit of the large cavity and the small cavity of the movable arm oil cylinder 5 is communicated, the pressure oil of the small cavity flows to the large cavity, and the pressure of the small cavity is reduced;

when the small cavity pressure P2 is reduced to be smaller than the excavator tilting pressure Pm preset in the controller 2, the controller 2 sends a control signal to the electromagnetic valve 4, so that the valve core of the electromagnetic valve 4 moves downwards, the electromagnetic valve 4 is in a normally closed working position, and at the moment, the oil passages of the large cavity and the small cavity of the movable arm oil cylinder 5 are closed.

It should be noted that: the excavator tilting pressure Pm preset in the controller 2 is a design parameter of the excavator, and refers to a minimum boom small cavity pressure value which can cause the excavator to tilt and influence the feeling of an operator when only the arm cylinder 7 and the bucket cylinder 9 are operated.

In a specific implementation manner of this embodiment, the control method of the present invention further includes the step of acquiring, by the sensor 6, a displacement value of the piston rod of the boom cylinder 5 relative to the cylinder barrel in real time, and transmitting the displacement value L to the controller 2.

In a specific implementation manner of this embodiment, the control method of the present invention further includes a boom position compensation method, specifically:

when the controller 2 detects that the excavator is performing land leveling work, the controller 2 does not receive an operation signal of the boom cylinder 5 of a driver, the controller 2 sends a control signal for switching to the conducting working position to the electromagnetic valve 4, and the controller 2 receives displacement of the piston of the boom cylinder 5 collected by the sensor 6, the position of the boom needs to be compensated, and the specific compensation method comprises the following steps:

the controller 2 sends a control signal to the control end of the movable arm reversing valve 3, so that the movable arm reversing valve 3 is switched to a right working position, at the moment, the small cavity of the movable arm oil cylinder 5 is filled with oil, and the piston rod of the movable arm oil cylinder 5 moves downwards;

the controller 2 calculates the difference between the real-time displacement value L3 of the piston rod of the movable arm oil cylinder 5 and the displacement value L1 of the movable arm piston rod before the electromagnetic valve 4 is switched to the conducting working position every delta t time to obtain a difference delta L1;

when the absolute value of Δ l1 falls within the range of the set value [ Δ l-n, Δ l + n ], the controller 2 sends a control signal to the boom changing valve 3 so that the boom changing valve 3 is switched to the middle working position to hold the position of the boom cylinder 5 at this time.

In a specific implementation manner of this embodiment, Δ L in the setting values is an absolute value of a displacement difference calculated by the controller 2 by performing a difference between a displacement value L1 of a piston rod of the boom cylinder 5 before the received electromagnetic valve 4 is switched to the on working position and a displacement value L2 of a piston rod of the boom cylinder 5 after the electromagnetic valve 4 is switched to the normally closed working position; n in the set values is a revised value of the displacement difference value of the oil cylinder of the excavator with different tonnages, the attitude of the excavator does not influence normal operation within an error range, both delta l and n are one of design parameters of the excavator, and if delta l1 is within a range of [ delta l-n, delta l + n ], the displacement of the piston rod of the movable arm oil cylinder 5 does not cause the influence of position compensation on flat ground operation.

In one embodiment of this embodiment, the boom position compensation action occurs after a time Δ k after the solenoid valve is switched to the normally closed operating position, where Δ k is a set value according to a common operating speed of different tonnages.

It is noted that, in the present application, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A hydraulic control system, characterized by: the hydraulic shovel loader comprises a movable arm oil cylinder, an arm oil cylinder, a shovel bucket oil cylinder, a movable arm reversing valve, an arm reversing valve, a shovel bucket reversing valve, a sensor, an electromagnetic valve and a controller; the movable arm oil cylinder is connected with the movable arm reversing valve, the bucket rod oil cylinder is connected with the bucket rod reversing valve, and the bucket oil cylinder is connected with the bucket reversing valve; the controller is respectively and electrically connected with two control ends of the movable arm reversing valve, the bucket rod reversing valve and the bucket reversing valve, the controller is electrically connected with the control end of the electromagnetic valve, and the controller is in communication connection with the sensor; the sensor is connected with the movable arm oil cylinder and used for acquiring the pressure of a large cavity and a small cavity of the movable arm oil cylinder and displacement signals of a piston rod of the movable arm oil cylinder and transmitting the pressure data and the displacement signals to the controller; an oil inlet of the electromagnetic valve is connected with a small cavity of the movable arm oil cylinder, an oil outlet of the electromagnetic valve is connected with a large cavity of the movable arm oil cylinder, the electromagnetic valve comprises a normally closed working position and a conducting working position, when excavation and land leveling operation are carried out, the movable arm reversing valve has no pilot pressure or pilot signals, and under the condition that the bucket reversing valve and the bucket rod reversing valve have pilot pressure or pilot signals, if the load is greater than the preset load, the controller sends a signal for switching to the conducting working position to the electromagnetic valve; the controller is also used for sending a signal for replacing the working position to the electromagnetic valve, the movable arm reversing valve, the bucket rod reversing valve and the bucket reversing valve according to the pressure data and the displacement signal acquired by the sensor and the operation signal of an operator.

2. A hydraulic control system according to claim 1, wherein: the hydraulic bucket reversing valve further comprises a hydraulic oil tank and a main pump, wherein an oil outlet of the main pump is respectively connected with an oil inlet C1 of the movable arm reversing valve, an oil inlet C2 of the bucket rod reversing valve and an oil inlet C3 of the bucket reversing valve, an oil outlet A1 of the movable arm reversing valve is connected with a large cavity of the movable arm oil cylinder, a small cavity of the movable arm oil cylinder is connected with an oil return opening B1 of the movable arm reversing valve, and an oil outlet D1 of the movable arm reversing valve is connected with the hydraulic oil tank; an oil outlet A2 of the bucket rod reversing valve is connected with a small cavity of the bucket rod oil cylinder, a large cavity of the bucket rod oil cylinder is connected with an oil return port B2 of the bucket rod reversing valve, and an oil outlet D2 of the bucket rod reversing valve is connected with a hydraulic oil tank; an oil outlet A3 of the bucket reversing valve is connected with a small cavity of the bucket oil cylinder, a large cavity of the bucket oil cylinder is connected with an oil return port B3 of the bucket reversing valve, and an oil outlet D3 of the bucket reversing valve is connected with a hydraulic oil tank.

3. A hydraulic control system according to claim 1, wherein: the hydraulic oil pump is characterized by further comprising an overflow valve, an oil inlet of the overflow valve is connected with an oil outlet of the main pump, and an oil outlet of the overflow valve is connected with the hydraulic oil tank.

4. A hydraulic control system according to claim 1, wherein: the hydraulic control valve further comprises a check valve group, an oil inlet of the check valve group is connected with the hydraulic oil tank, and an oil outlet of the check valve group is connected with an oil inlet E of the movable arm reversing valve.

5. A hydraulic control system according to claim 1, wherein: all 6 ports of the working position in the bucket rod reversing valve are not communicated with each other; the oil port C2 of the left working position is communicated with the oil port A2, and the oil port B2 is communicated with the oil port D2; and the oil port C2 of the right working position is communicated with the oil port B2, and the oil port A2 is communicated with the oil port D2.

6. A hydraulic control system according to claim 1, wherein: no 6 ports of the working position in the bucket reversing valve are communicated with each other; the oil port C3 of the left working position is communicated with the oil port A3, and the oil port B3 is communicated with the oil port D3; and an oil port C3 of the right working position is communicated with an oil port B3, and an oil port A3 is communicated with an oil port D3.

7. A hydraulic control system according to claim 1, wherein: an oil port A1 and an oil port E of a working position in the movable arm reversing valve are communicated, and the rest oil ports are not communicated with each other; the oil port C1 of the left working position is communicated with the oil port A1, and the oil port B1 is communicated with the oil port D1; the oil port C1 of the right working position is communicated with the oil port B1, and the oil port A1 is communicated with the oil port D1.

8. A control method of a hydraulic control system is characterized in that: the hydraulic control system according to any one of claims 1 to 7, comprising the steps of:

excavating or leveling work;

when the movable arm reversing valve has no pilot pressure or pilot signals, and the bucket reversing valve and the arm reversing valve have pilot pressures or pilot signals, the controller compares pressure data from the sensor with excavator tilting pressure Pm preset in the controller;

9. The control method of a hydraulic control system according to claim 8, characterized in that: the system also comprises a sensor for acquiring the displacement value of the piston rod of the movable arm oil cylinder relative to the cylinder barrel in real time and transmitting the displacement value L to the controller.

10. The control method of a hydraulic control system according to claim 9, characterized in that: the method further comprises a movable arm position compensation method, and specifically comprises the following steps:

when the absolute value of the delta l1 falls into the range of a set value [ delta l-n, delta l + n ], the controller sends a control signal to the movable arm reversing valve, so that the movable arm reversing valve is switched to a middle working position to keep the position of the movable arm oil cylinder at the moment; in the set value, delta L is an absolute value of a displacement difference obtained by calculating the difference between a displacement value L1 of a piston rod of the movable arm oil cylinder before the received electromagnetic valve is switched to a conducting working position and a displacement value L2 of the piston rod of the movable arm oil cylinder after the electromagnetic valve is switched to a normally closed working position by the controller; and n in the set value is a revised value of the displacement difference value of the oil cylinder of the excavator with different tonnages.