Loader and hydraulic system thereof

Abstract

The invention relates to a loader and provides a loader and a hydraulic system thereof in order to solve the problem that an existing loader hydraulic system is insufficient in refined operation. The loader hydraulic system comprises a controller, a movable arm oil cylinder, a bucket oil cylinder, a working pump, a steering pump, a steering operation mechanism and an action operation mechanism, the movable arm oil cylinder and the bucket oil cylinder are composed of digital oil cylinders, the steering operation mechanism is used for generating steering electric signals, the action operation mechanism is used for generating action electric signals, the steering pump is connected with a confluence control valve, and a first working oil port of the confluence control valve is connected with the steering mechanism. The second working oil port is in confluence connection with the working pump; the confluence control valve is electrically connected with the controller, and the controller controls the confluence control valve and outputs pulse equivalent signals to stepping motors of the movable arm oil cylinder and the bucket oil cylinder according to the steering electric signals and the action electric signals. According to the hydraulic system, the movable arm oil cylinder, the bucket oil cylinder and even the steering oil cylinder are digital oil cylinders and are directly controlled by the controller, and accurate control is achieved.

Description

Technical Field

[0001] The present invention relates to a loader, and more particularly to a loader and a hydraulic system thereof. Background Art

[0002] The loader hydraulic system mainly includes hydraulic pump, boom cylinder, bucket cylinder, multi-way valve, and pilot control device. The multi-way valve connects the hydraulic pump with the boom cylinder and bucket cylinder. The pilot control device is connected to the multi-way valve to control the working position and valve opening of each main valve in the multi-way valve. The flow direction and flow rate of the hydraulic oil flowing to each cylinder are controlled by controlling the multi-way valve. When fine operation is required, a sensor is set to detect the elongation or rotation angle of the corresponding cylinder to determine the posture of the cylinder. According to the posture of the cylinder, the multi-way valve is controlled by the pilot control device to accurately control the corresponding cylinder.

[0003] The above hydraulic system has many deficiencies when performing fine operation control, such as poor environmental adaptability, sensors often report feedback errors or reduce control accuracy due to external factors such as rain, snow, and temperature; valve response lag, when displacement deviation is detected, it is necessary to control the output flow of the multi-way valve through the electric proportional valve to correct the deviation of the cylinder, but both the electric proportional valve and the multi-way valve require time to respond. During this process, the displacement of the cylinder will have a greater deviation, and adjustments such as over-adjustment, under-adjustment or repeated adjustments often occur; in addition, the control system has high requirements: the adjustment process needs to continuously adjust the power on and off of the electric proportional valve according to the final displacement feedback, and has high requirements for algorithms and software control strategies. Summary of the invention

[0004] The technical problem to be solved by the present invention is the deficiency of the existing loader hydraulic system in fine operation, and a loader and a hydraulic system thereof are provided.

[0005] The technical solution of the present invention to achieve its purpose is: a loader hydraulic system, including a controller and:

[0006] The boom cylinder and the bucket cylinder are digital cylinders including a stepper motor and a servo reversing valve; the stepper motor of each cylinder is electrically connected to the controller;

[0007] A working pump connected to the boom cylinder and the bucket cylinder, and used for supplying working pressure oil to the boom cylinder and the bucket cylinder;

[0008] A steering pump connected to a merging control valve, wherein a first working oil port of the merging control valve is connected to a steering mechanism, and a second working oil port is mergingly connected to the working pump;

[0009] A steering operating mechanism, electrically connected to the controller, for generating a steering electrical signal;

[0010] An action operating mechanism, electrically connected to the controller, for generating an action electrical signal, wherein the action electrical signal includes an action electrical signal of the boom when the boom cylinder is extended and retracted and an action electrical signal of the bucket when the bucket cylinder is extended and retracted;

[0011] The confluence control valve is electrically connected to the controller, and the controller outputs a flow distribution control current to the confluence control valve and a pulse equivalent signal to the stepper motors of the boom cylinder and the bucket cylinder according to the steering electrical signal and the action electrical signal.

[0012] In the loader hydraulic system of the present invention, the steering mechanism includes a steering cylinder composed of a digital cylinder, and the stepper motor of the steering cylinder is electrically connected to the controller; the controller outputs a pulse equivalent signal to the stepper motor of the steering cylinder according to the steering electrical signal.

[0013] In the loader hydraulic system of the present invention, the confluence control valve comprises a hydraulically controlled three-position three-way valve and a three-position two-way solenoid valve;

[0014] The oil inlet of the hydraulically controlled three-position three-way valve is connected to the steering pump, and the other two oil ports are respectively the first working oil port and the second working oil port. The hydraulically controlled end is connected to the first working oil port through a throttle hole, and its valve stem slides under the pressure of the hydraulically controlled end to adjust the respective valve port openings between the oil inlet and the first working oil port and the second working oil port;

[0015] The electric control end of the three-position two-way solenoid valve is connected to the controller, and its two oil ports are correspondingly connected to the hydraulic control end and the return oil circuit of the hydraulically controlled three-position three-way valve. Its valve stem moves under the drive of its electromagnet to adjust the valve port opening between the two oil ports.

[0016] In the loader hydraulic system of the present invention, when the hydraulically controlled three-position three-way valve is in the left position under the control of the spring force of its spring chamber, the oil circuit between its oil inlet and the first working oil port is connected and the valve opening reaches the maximum, and the oil circuit between the oil inlet and the second working oil port is cut off; when the hydraulically controlled three-position three-way valve is in the right position under the control of the oil pressure at its hydraulic control end, the oil circuit between its oil inlet and the first working oil port is connected and the valve opening reaches the minimum, and the oil circuit between the oil inlet and the second working oil port is connected and the valve opening reaches the maximum.

[0017] In the loader hydraulic system of the present invention, the working pump and / or the steering pump is a variable displacement pump with adjustable displacement and a displacement regulating electronic control end electrically connected to the controller.

[0018] In the loader hydraulic system of the present invention, the system further comprises a first cut-off valve and / or a second cut-off valve;

[0019] The oil inlet end of the first cut-off valve is connected to the pump port of the steering pump, the oil outlet end is communicated with the hydraulic oil tank, and a throttle valve for establishing back pressure is provided on the oil path between the oil inlet end and the hydraulic oil tank;

[0020] The oil inlet end of the second cut-off valve is connected to the pump port of the working pump, the oil outlet end is communicated with the hydraulic oil tank, and a throttle valve for establishing back pressure is provided on the oil path between the oil inlet end and the hydraulic oil tank;

[0021] The controller is electrically connected to the electric control end of the first cut-off valve and the electric control end of the second cut-off valve and controls the oil circuit between the oil inlet end and the oil outlet end of each cut-off valve to be connected or cut off.

[0022] In the loader hydraulic system of the present invention, the system further comprises a first overflow valve and / or a second overflow valve;

[0023] The oil inlet end of the first relief valve is connected to the pump port of the steering pump, and the oil outlet end is communicated with the hydraulic oil tank;

[0024] The oil inlet end of the second overflow valve is connected to the pump port of the working pump, and the oil outlet end is communicated with the hydraulic oil tank.

[0025] In the loader hydraulic system of the present invention, the steering operating mechanism includes a steering motor and a steering machine for rotating the steering motor, and the steering motor is electrically connected to the controller;

[0026] Or the steering operating mechanism includes a steering gear, a steering machine driving the steering gear, and a speed sensor for detecting the speed of the steering machine, and the speed sensor is electrically connected to the controller;

[0027] Alternatively, the steering operating mechanism is a remote control receiver electrically connected to the controller for receiving an operating signal.

[0028] In the loader hydraulic system of the present invention, the action operating mechanism is an electrically controlled pilot handle electrically connected to the controller, or the action operating mechanism is a remote control receiver electrically connected to the controller for receiving an operation signal.

[0029] The technical solution of the present invention to achieve its purpose is: a loader having the above-mentioned loader hydraulic system.

[0030] Compared with the prior art, in the present invention, the boom cylinder, the bucket cylinder and even the steering cylinder are in the form of digital cylinders, which are directly controlled by a controller to achieve precise control. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the hydraulic system of the loader of the present invention.

[0032] Parts names and serial numbers in the figure:

[0033] Hydraulic oil tank 1, steering pump 21, working pump 22, confluence control valve 3, hydraulically controlled three-position three-way valve 31, three-position two-way solenoid valve 32, controller 4, steering operating mechanism 5, action operating mechanism 6, first cut-off valve 71, second cut-off valve 72, first overflow valve 81, second overflow valve 82, steering cylinder 91, boom cylinder 92, bucket cylinder 93. DETAILED DESCRIPTION

[0034] The specific implementation scheme is described below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, the loader hydraulic system includes a controller 4, a boom cylinder 92, a bucket cylinder 93, a working pump 22, a steering pump 21, a steering operating mechanism 5, an action operating mechanism 6, a hydraulic oil tank 1, etc.

[0036] The boom cylinder 92 and the bucket cylinder 93 are both digital cylinders including a stepper motor and a servo reversing valve; the stepper motor of each cylinder is electrically connected to the controller 4;

[0037] The working pump 22 is connected to the boom cylinder 92 and the bucket cylinder 93 through pipelines, and is used to supply working pressure oil to the boom cylinder 92 and the bucket cylinder 93;

[0038] The steering pump 21 is connected to the confluence control valve 3, the first working oil port of the confluence control valve 3 is connected to the steering mechanism, and the second working oil port is confluence-connected to the working pump 22. The hydraulic oil output from the second working oil port and the pressure oil output from the working pump 22 merge and flow to the boom cylinder 92 and the bucket cylinder 93.

[0039] The steering operating mechanism 5 is electrically connected to the controller 4 and is used to generate a steering electrical signal.

[0040] The motion operating mechanism 6 is electrically connected to the controller 4 and is used to generate motion electrical signals, including the boom motion electrical signals of the boom cylinder 92 extending and retracting and the bucket motion electrical signals of the bucket cylinder 93 extending and retracting.

[0041] The confluence control valve 3 is electrically connected to the controller 4 , and the controller 4 outputs a flow distribution control current to the confluence control valve 3 and a pulse equivalent signal to the stepper motors of the boom cylinder 92 and the bucket cylinder 93 according to the steering electrical signal and the action electrical signal.

[0042] In this embodiment, the boom cylinder 92 and the bucket cylinder 93 include a stepper motor and a servo reversing valve, and are a type of hydraulic cylinder with mechanical negative feedback characteristics. The stepper motor has the characteristic of pulse equivalent, which indicates the distance that the hydraulic cylinder piston moves through a lead screw or other transmission device after the stepper motor receives a pulse signal. Cylinder piston movement distance = pulse equivalent x number of pulses, cylinder piston movement speed = pulse equivalent x pulse frequency; the minimum pulse equivalent can reach 0.001 mm. Therefore, the digital cylinder can be used to achieve precise position control of the working device.

[0043] In this embodiment, the hydraulic system of the working device of the loader hydraulic system is a closed-loop system: the action operating mechanism 6 inputs a signal to the controller 4, and the controller 4 outputs a corresponding pulse equivalent signal to the stepper motor of the boom cylinder and the bucket cylinder, and the stepper motor drives the servo reversing valve stem to open; the working pump 22 and the steering pump 21 output flow and enter the cylinder through the servo reversing valve to drive the piston rod to move, and the boom cylinder 92 and the bucket cylinder 93 move and then close the valve stem. When the action operating mechanism 6 remains stationary, the controller 4 continuously outputs a pulse equivalent signal to drive the stepper motor, and the cylinder will continue to extend or retract; when the action operating mechanism 6 returns to the center, the stepper motor has no pulse signal input, the servo reversing valve is closed, and the cylinder stops moving.

[0044] Optionally, the steering mechanism includes a steering cylinder 91 composed of a digital cylinder, and the stepper motor of the steering cylinder 91 is electrically connected to the controller 4; the controller 4 outputs a pulse equivalent signal to the steering cylinder 91 according to the steering electrical signal. The steering cylinder 91 adopts a digital cylinder, and precise control of steering can also be achieved. In other embodiments, the steering mechanism can also be composed of a steering cylinder, a flow amplification valve for controlling the telescopic flow of the steering cylinder, and a steering gear for controlling the flow amplification valve. In order to obtain the steering electrical signal, a speed sensor can be set to detect the speed of the steering machine.

[0045] Optionally, the confluence control valve 3 includes a hydraulically controlled three-position three-way valve 31 and a three-position two-way solenoid valve 32 .

[0046] The oil inlet of the hydraulically controlled three-position three-way valve 31 is connected to the steering pump 21, and the other two oil ports are respectively the first working oil port and the second working oil port. The first working oil port is connected to the steering mechanism, for example, the steering cylinder, and the hydraulic control end is connected to the first working oil port through a throttle hole. The valve stem slides under the pressure of the hydraulic control end to adjust the valve port openings between the oil inlet and the first working oil port and the second working oil port.

[0047] The electric control end of the three-position two-way solenoid valve 32 is connected to the controller 4, and its two oil ports are correspondingly connected to the hydraulic control end and the return oil circuit of the hydraulically controlled three-position three-way valve 31. Its valve stem moves under the drive of its electromagnet to adjust the valve port opening between the two oil ports.

[0048] Furthermore, when the hydraulically controlled three-position three-way valve 31 is in the left position under the control of the spring force of its spring chamber, the oil circuit between its oil inlet and the first working oil port is connected and the valve opening reaches the maximum, and the oil circuit between the oil inlet and the second working oil port is cut off; when the hydraulically controlled three-position three-way valve 31 is in the right position under the control of the oil pressure at its hydraulic control end, the oil circuit between its oil inlet and the first working oil port is connected and the valve opening reaches the minimum, and the oil circuit between the oil inlet and the second working oil port is connected and the valve opening reaches the maximum.

[0049] When the three-position two-way solenoid valve 32 is powered off, the oil circuit between its oil inlet and oil outlet is in a cut-off state, and the pressure oil of the first working oil port of the hydraulically controlled three-position three-way valve 31 enters the hydraulically controlled end of the hydraulically controlled three-position three-way valve 31 through the throttle hole, and pressure is established at the hydraulically controlled end. The valve stem of the hydraulically controlled three-position three-way valve 31 moves to the limit position in the direction of the spring chamber under the action of the hydraulic oil at its hydraulically controlled end. At this time, the hydraulically controlled three-position three-way valve 31 is in the right position, and the oil circuit between its oil inlet and the first working oil port is connected and the valve opening is minimized. The minimum opening valve opening between the oil inlet and the first working oil port allows the first working oil port to have pressure oil flowing out, so that the pressure oil flows to the hydraulically controlled end of the hydraulically controlled three-position three-way valve through the throttle hole. The oil circuit between the oil inlet and the second working oil port is connected and the valve opening is maximized, so that the flow output by the steering pump is combined with the working pump to supply the boom cylinder and the bucket cylinder.

[0050] When the controller 4 delivers the maximum control current to the three-position two-way solenoid valve 32, the oil circuit between the oil inlet and the oil outlet of the three-position two-way solenoid valve 32 is in a conducting state, and the hydraulic control end of the hydraulically controlled three-position three-way valve 31 cannot build up pressure. The valve stem of the hydraulically controlled three-position three-way valve 31 moves toward the hydraulic control end to the limit position under the action of the spring force of its spring chamber. At this time, the hydraulically controlled three-position three-way valve 31 is in the left position, and the oil circuit between its oil inlet and the first working oil port is connected and the valve port reaches the maximum, and the oil circuit between the oil inlet and the second working oil port is cut off, so that the flow output by the steering pump 21 flows to the steering mechanism.

[0051] By controlling the control current of the three-position two-way solenoid valve 32, the valve opening between the oil inlet and the oil outlet of the three-position two-way solenoid valve 32 can be controlled, thereby controlling the pressure at the hydraulic control end of the hydraulically controlled three-position three-way valve 31, and then controlling the valve stem position of the hydraulically controlled three-position three-way valve 31, thereby adjusting the respective valve openings between the oil inlet of the hydraulically controlled three-position three-way valve 31 and the first working oil port and the second working oil port, thereby achieving the distribution of the output flow of the steering pump 21 between the steering mechanism and the working device (boom cylinder, bucket cylinder).

[0052] Optionally, the working pump 22 is a variable displacement pump with adjustable displacement and the displacement adjustment electronic control end is electrically connected to the controller 4. The controller 4 can output a control current to adjust the displacement of the working pump 22 as needed, thereby adjusting its output flow so that its output flow meets the demand without excessive surplus causing waste.

[0053] Similarly, the steering pump 21 may also be a variable displacement pump with adjustable displacement and a displacement adjustment electronic control terminal electrically connected to the controller 4. The controller may output a control current to adjust the displacement of the steering pump as required, thereby adjusting its output flow rate.

[0054] Optionally, the loader hydraulic system may further include a first cut-off valve 71, which is a two-position two-way solenoid valve, the oil inlet end of which is connected to the pump port of the steering pump 21, the oil outlet end of which is connected to the hydraulic oil tank 1, and a throttle valve for establishing back pressure is provided on the oil path between the oil inlet end and the hydraulic oil tank. When the steering pump 21 enters the standby state, its displacement is at a minimum value, at which time the first cut-off valve 71 is turned on, further reducing the pressure at the pump port of the steering pump 21, realizing low-pressure unloading, and further reducing the energy consumed by the steering pump 21 when in standby state.

[0055] Similarly, the loader hydraulic system may also include a second cut-off valve 72; the second cut-off valve 72 is a two-position two-way solenoid valve, the oil inlet end is connected to the pump port of the working pump 22, the oil outlet end is connected to the hydraulic oil tank 1, and a throttle valve for establishing back pressure is provided on the oil path between the oil inlet end and the hydraulic oil tank. When the working pump 22 enters the standby state, its displacement is at the minimum value, at which time the second cut-off valve 72 is turned on, further reducing the pressure at the pump port of the working pump 22, realizing low-pressure unloading, and further reducing the energy consumed by the working pump when in standby state.

[0056] Optionally, the loader hydraulic system may further include a first relief valve 81, the oil inlet of the first relief valve 81 is connected to the pump port of the steering pump 21, and the oil outlet is connected to the hydraulic oil tank 1. The first relief valve 81 is opened to relieve the load when the pressure at the pump port of the steering pump 21 reaches its relief setting pressure, and it is used as a safety valve to prevent excessive pressure caused by excessive load.

[0057] Similarly, the loader hydraulic system may further include a second relief valve 82; the oil inlet end of the second relief valve 82 is connected to the pump port of the working pump, and the oil outlet end is connected to the hydraulic oil tank 1. The second relief valve 82 is opened to relieve the load when the pump port pressure of the working pump 22 reaches its relief setting pressure. It is used as a safety valve to prevent excessive pressure caused by excessive load.

[0058] Optionally, the steering operating mechanism 5 includes a steering motor and a steering gear for rotating the steering motor, and the steering motor is electrically connected to the controller. The steering motor is rotated by rotating the direction, and the steering motor outputs a steering electrical signal to the controller.

[0059] The steering operating mechanism 5 can also be in other structural forms, for example, it can also include a steering gear, a steering machine driving the steering gear, and a speed sensor for detecting the speed of the steering machine, and the speed sensor is electrically connected to the controller. The speed sensor detects the speed of the steering machine and converts it into a steering electrical signal to be transmitted to the controller, and the controller controls the steering according to the electrical signal. The steering operating mechanism is a remote control receiver electrically connected to the controller for receiving an operating signal; the loader can be a remote control operating device, and its on-board remote control receiver receives the remote control signal and transmits the steering signal therein to the controller, and the controller controls the steering of the loader.

[0060] Optionally, the action operating mechanism 6 is an electric pilot handle electrically connected to the controller. When the electric pilot handle is swung, it generates corresponding boom action signals and bucket action electrical signals according to the direction and amplitude of its own swing and transmits them to the controller. The action operating mechanism can also be a remote control receiver electrically connected to the controller for receiving operation signals. The loader can be a remote control operation device, and its on-board remote control receiver receives the remote control signal and transmits the boom action signal and bucket action signal therein to the controller, and the controller controls the action of the working device of the loader.

[0061] This embodiment also provides a loader having the aforementioned loader hydraulic system.

[0062] In the present invention, the boom cylinder 92, the bucket cylinder 93 and even the steering cylinder 91 are in the form of digital cylinders, which are directly controlled by the controller 4 to achieve precise control.

[0063] In this embodiment, when the whole machine is started and there is no action, the first shut-off valve 71 and the second shut-off valve 72 are both de-energized and work in their respective left positions; the controller 4 outputs a small current to the steering pump 21 and the working pump 22, so that the steering pump 21 and the working pump 22 output a small flow of 3-5L / min at idle speed. Under the action of the small flow, the steering pump 21 and the working pump 22 return oil through the first shut-off valve 71 and the second shut-off valve 72 respectively, and generate a standby pressure of about 2-3Mpa.

[0064] The three-position two-way solenoid valve 32 in the confluence control valve 3 is in a power-off state, and the hydraulically controlled end of the hydraulically controlled three-position three-way valve 31 returns oil through the right position of the three-position two-way solenoid valve 32. The hydraulically controlled three-position three-way valve 31 is in the left position under the action of the spring force, that is, the steering pump 21 only supplies oil to the steering cylinder 91.

[0065] When the whole machine performs a separate steering operation, the controller 4 controls the three-position two-way solenoid valve 32 in the confluence control valve 3 to be in a power-off state, and the hydraulically controlled three-position three-way valve 31 is in the left position under the action of the spring force.

[0066] The steering operating mechanism 5 transmits the steering electrical signal to the controller 4. After receiving the steering electrical signal, the controller 4 outputs three signals: the first signal drives the stepper motor of the steering cylinder 91 to push the servo valve to open; the second signal controls the first cut-off valve 71 to switch to the right position within a certain period of time, and the steering pump 21 starts to supply oil to the steering cylinder; the third signal controls the steering pump 21 to increase to the desired displacement, and the output flow of the steering pump 21 enters through the servo valve of the steering cylinder to realize left and right steering of the whole machine.

[0067] The output flow of the steering pump 21 is associated with the steering electrical signal of the steering operating mechanism 5. The displacement of the steering pump 21 is adjusted in real time according to the speed of the engine or hydraulic motor driving the steering pump 21. The maximum output flow of the steering pump 21 is limited within a certain flow range (e.g., a maximum of no more than 100L / min).

[0068] The steering operating mechanism 5 is continuously operated, and the steering cylinder 91 continuously repeats the process of valve stem pushing out, cylinder movement, valve stem closing, and valve stem being pushed out again; during this steering process, the first shut-off valve 71 remains energized and works in the right position, the confluence control valve 3 remains de-energized, and the steering pump 21 always outputs flow to the outside.

[0069] When the steering stops, the controller 4 first stops the stepper motor signal to the steering cylinder 91, then gradually reduces the displacement of the steering pump 21 to the minimum value, and at the same time, the first cut-off valve 71 is powered off. When the steering cylinder 91 stops steering, the valve stem is closed by the movement of the cylinder, and the steering cylinder 91 stops moving.

[0070] When the operating mechanism 6 is manipulated with a small amplitude to make the working device move alone (the boom cylinder or bucket cylinder is extended or retracted, and the boom lifting is taken as an example below), the three-position two-way solenoid valve 32 in the confluence control valve 3 is in the power-off state, and the hydraulically controlled three-position three-way valve 31 is in the left position under the action of the spring force.

[0071] At this time, the action operating mechanism 6 outputs an action electrical signal to the controller. After receiving the action electrical signal, the controller 4 outputs three signals: the first signal drives the stepper motor of the boom cylinder 92 to push the servo valve to open; the second signal controls the second cut-off valve 72 to switch to the right position within a certain period of time, and the working pump 22 starts to supply oil to the boom cylinder 92; the third signal controls the working pump 22 to increase to the maximum displacement, and the output flow of the working pump 22 enters the boom cylinder through the servo valve to realize the extension or retraction of the boom cylinder.

[0072] When the working device moves alone and continuously increases the operating amplitude of the action operating mechanism 6 to a certain critical value, the three-position two-way solenoid valve 32 of the confluence control valve 3 is energized to switch it to the left position; the pressure relief oil circuit of the hydraulic control end of the hydraulic three-position three-way valve 31 is cut off, and the pressure of the steering pump 21 acts on the hydraulic control end of the hydraulic three-position three-way valve 31 to overcome the effect of the spring force, so that the hydraulic three-position three-way valve 31 works in the right position, and the steering pump 22 starts to supply oil to the working system. At the same time, the controller 4 adds two output signals: the first one controls the first cut-off valve 71 to switch to the right position within a certain period of time, and the steering pump 21 also starts to supply oil to the boom cylinder 92; the second one controls the steering pump 21 to increase to the maximum displacement, and the output flow of the steering pump 21 and the working pump 22 enters the boom cylinder 92 through the servo valve to achieve the lifting or lowering of the boom;

[0073] When the steering operating mechanism 5 and the action operating mechanism 6 are operated at the same time, and the whole machine is turned and the working device moves at the same time, the three-position two-way solenoid valve 32 of the confluence control valve 3 is energized to switch it to the middle position; the right end of the hydraulically controlled three-position three-way valve 31 returns to the oil tank after being damped, and the pressure of the steering pump 21 acts on the hydraulically controlled end of the hydraulically controlled three-position three-way valve 31 to overcome the effect of the spring force, so that the hydraulically controlled three-position three-way valve 31 works in the middle position, and the steering pump 22 can supply oil to the steering cylinder 91, the boom cylinder 92 and the bucket cylinder 93 at the same time; at this time, the steering operating mechanism 5 and the action operating mechanism 6 both have output The controller 4 outputs a signal to the controller 4. After receiving the steering electrical signal and the action electrical signal, the controller 4 controls the stepper motor of each cylinder to push the servo valve to open; at the same time, the first shut-off valve 71 and the second shut-off valve 72 are controlled to switch to the right position within a certain period of time, and the steering pump 21 and the working pump 22 begin to supply oil to the dynamic system; the controller 4 also controls the steering pump 21 and the working pump 22 to gradually increase the displacement to meet the movement speed of the steering cylinder 91, the boom cylinder 92 and the bucket cylinder 93; the excess flow of the steering pump 21 can also enter the boom cylinder 92 and the bucket cylinder 93 through the confluence control valve 3.

Claims

1. A loader hydraulic system, characterized in that: Includes controller and: The boom cylinder and the bucket cylinder are digital cylinders including a stepper motor and a servo reversing valve; the stepper motor of each cylinder is electrically connected to the controller; A working pump connected to the boom cylinder and the bucket cylinder, and used for supplying working pressure oil to the boom cylinder and the bucket cylinder; A steering pump connected to a merging control valve, wherein a first working oil port of the merging control valve is connected to a steering mechanism, and a second working oil port is mergingly connected to the working pump; A steering operating mechanism, electrically connected to the controller, for generating a steering electrical signal; An action operating mechanism, electrically connected to the controller, for generating an action electrical signal, wherein the action electrical signal includes an action electrical signal of the boom when the boom cylinder is extended and retracted and an action electrical signal of the bucket when the bucket cylinder is extended and retracted; The confluence control valve is electrically connected to the controller, and the controller outputs a flow distribution control current to the confluence control valve and a pulse equivalent signal to the stepper motors of the boom cylinder and the bucket cylinder according to the steering electrical signal and the action electrical signal.

2. The loader hydraulic system according to claim 1, characterized in that: The steering mechanism comprises a steering cylinder composed of a digital cylinder, and the stepper motor of the steering cylinder is electrically connected to the controller; the controller outputs a pulse equivalent signal to the stepper motor of the steering cylinder according to the steering electrical signal.

3. The loader hydraulic system according to claim 1 or 2, characterized in that: The confluence control valve includes a hydraulically controlled three-position three-way valve and a three-position two-way solenoid valve; The oil inlet of the hydraulically controlled three-position three-way valve is connected to the steering pump, and the other two oil ports are respectively the first working oil port and the second working oil port. The hydraulically controlled end is connected to the first working oil port through a throttle hole, and its valve stem slides under the pressure of the hydraulically controlled end to adjust the respective valve port openings between the oil inlet and the first working oil port and the second working oil port; The electric control end of the three-position two-way solenoid valve is connected to the controller, and its two oil ports are correspondingly connected to the hydraulic control end and the return oil circuit of the hydraulically controlled three-position three-way valve. Its valve stem moves under the drive of its electromagnet to adjust the valve port opening between the two oil ports.

4. The loader hydraulic system according to claim 3, characterized in that: When the hydraulically controlled three-position three-way valve is in the left position under the control of the spring force of its spring chamber, the oil circuit between the oil inlet and the first working oil port is connected and the valve opening reaches the maximum, and the oil circuit between the oil inlet and the second working oil port is cut off; when the hydraulically controlled three-position three-way valve is in the right position under the control of the oil pressure at its hydraulic control end, the oil circuit between the oil inlet and the first working oil port is connected and the valve opening reaches the minimum, and the oil circuit between the oil inlet and the second working oil port is connected and the valve opening reaches the maximum.

5. The loader hydraulic system according to claim 1 or 2, characterized in that: The working pump and / or the steering pump are variable displacement pumps with adjustable displacement and a displacement regulating electronic control end electrically connected to the controller.

6. The loader hydraulic system according to claim 1 or 2, characterized in that: The system also includes a first shut-off valve and / or a second shut-off valve; The oil inlet end of the first cut-off valve is connected to the pump port of the steering pump, the oil outlet end is communicated with the hydraulic oil tank, and a throttle valve for establishing back pressure is provided on the oil path between the oil inlet end and the hydraulic oil tank; The oil inlet end of the second cut-off valve is connected to the pump port of the working pump, the oil outlet end is communicated with the hydraulic oil tank, and a throttle valve for establishing back pressure is provided on the oil path between the oil inlet end and the hydraulic oil tank; The controller is electrically connected to the electric control end of the first cut-off valve and the electric control end of the second cut-off valve and controls the oil circuit between the oil inlet end and the oil outlet end of each cut-off valve to be connected or cut off.

7. The loader hydraulic system according to claim 5, characterized in that: The system further comprises a first relief valve and / or a second relief valve; The oil inlet end of the first relief valve is connected to the pump port of the steering pump, and the oil outlet end is communicated with the hydraulic oil tank; The oil inlet end of the second overflow valve is connected to the pump port of the working pump, and the oil outlet end is communicated with the hydraulic oil tank.

8. The loader hydraulic system according to claim 1 or 2, characterized in that: The steering operating mechanism includes a steering motor and a steering machine for rotating the steering motor, and the steering motor is electrically connected to the controller; Or the steering operating mechanism includes a steering gear, a steering machine driving the steering gear, and a speed sensor for detecting the speed of the steering machine, and the speed sensor is electrically connected to the controller; Alternatively, the steering operating mechanism is a remote control receiver electrically connected to the controller for receiving an operating signal.

9. The loader hydraulic system according to claim 1 or 2, characterized in that: The action operating mechanism is an electrically controlled pilot handle electrically connected to the controller, or the action operating mechanism is a remote control receiver electrically connected to the controller for receiving an operation signal.

10. A loader, characterized in that: A loader hydraulic system according to any one of claims 1 to 9.

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