Loader and hydraulic system thereof

Abstract

The utility model relates to a loading machine, and provides a loading machine and a hydraulic system thereof in order to solve the problem that an existing hydraulic system of the loading machine is insufficient in the aspect of fine 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 utility model, the movable arm oil cylinder, the bucket oil cylinder and even the steering oil cylinder adopt a digital oil cylinder form and are directly controlled by the controller, so that accurate control is realized.

Description

Technical Field

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

[0002] The loader's hydraulic system primarily consists of a hydraulic pump, boom cylinder, bucket cylinder, multi-way valve, and pilot control unit. The multi-way valve connects the hydraulic pump to the boom and bucket cylinders, while the pilot control unit, connected to the multi-way valve, controls the operating position and valve opening of each main valve in the multi-way valve. By controlling the multi-way valve, the direction and flow rate of the hydraulic oil flowing to each cylinder are controlled. When fine manipulation is required, sensors are installed to detect the extension or rotation angle of the corresponding cylinder to determine the cylinder's posture. Based on the cylinder's posture, the pilot control unit controls the multi-way valve to precisely control the corresponding cylinder.

[0003] The above-mentioned hydraulic system has many shortcomings when performing fine operation control, such as poor environmental adaptability, and the sensor often reports feedback errors or reduces control accuracy due to external factors such as rain, snow, and temperature; the valve response is delayed, and when a 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 will often be excessive, insufficient, or repeated. 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 high requirements are placed on the algorithm, software control strategy, etc. Utility Model Content

[0004] The technical problem to be solved by the utility model 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 for achieving the purpose of the utility model is: a loader hydraulic system, including a controller and:

[0006] The boom cylinder and bucket cylinder are digital cylinders that include 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, for supplying working pressure oil to the boom cylinder and the bucket cylinder;

[0008] A steering pump is connected to a merging control valve, wherein a first working oil port of the merging control valve is connected to the 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 and configured to generate an action electrical signal, wherein the action electrical signal includes an arm action electrical signal for extension and retraction of the arm cylinder and a bucket action electrical signal for extension and retraction of the bucket cylinder;

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

[0012] In the hydraulic system of the loader of the present invention, the steering mechanism includes a steering cylinder composed of a digital cylinder, 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 hydraulic system of the loader of the utility model, the confluence control valve includes 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 a first working oil port and a second working oil port. The hydraulic control end is connected to the first working oil port through a throttle hole, and its valve stem slides under the pressure of the hydraulic control end to adjust the valve port opening between the oil inlet and the first working oil port and the second working oil port respectively;

[0015] The electrical 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 hydraulic system of the loader of the present utility model, 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.

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

[0018] In the hydraulic system of the loader of the utility model, the system further comprises a first shut-off valve and / or a second shut-off valve;

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

[0020] The oil inlet end of the second shut-off valve is connected to the pump port of the working pump, and 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 shut-off valve and the electric control end of the second shut-off valve and controls the oil circuit between the oil inlet end and the oil outlet end of each shut-off valve to be connected or cut off.

[0022] In the hydraulic system of the loader of the utility model, the system further comprises a first relief valve and / or a second relief 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 hydraulic system of the loader of the present utility model, 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 that drives 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 hydraulic system of the loader 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 for achieving the purpose of the utility model 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 the controller to achieve precise control. BRIEF DESCRIPTION OF THE DRAWINGS

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

[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 shut-off valve 71, second shut-off valve 72, first relief valve 81, second relief 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, an arm 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 that include 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 boom motion electrical signals for the boom cylinder 92 to extend and retract, and bucket motion electrical signals for the bucket cylinder 93 to extend and retract.

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

[0042] In this embodiment, the boom cylinder 92 and bucket cylinder 93 comprise stepper motors and servo reversing valves, forming a hydraulic cylinder with mechanical negative feedback. Stepper motors have a pulse equivalent characteristic, which represents the distance the hydraulic cylinder piston moves via a lead screw or other transmission device after each pulse signal received by the stepper motor. Cylinder piston movement distance = pulse equivalent x number of pulses, and cylinder piston movement speed = pulse equivalent x pulse frequency. The minimum pulse equivalent can reach 0.001 mm. Therefore, this digital cylinder can achieve precise position control of the working device.

[0043] In this embodiment, the working device hydraulic system of the loader's hydraulic system is a closed-loop system: the motion operating mechanism 6 inputs a signal to the controller 4, which then outputs a corresponding pulse equivalent signal to the stepper motors of the boom and bucket cylinders. The stepper motors then push the servo reversing valve stems to open. The flow output from the working pump 22 and steering pump 21 enters the cylinders through the servo reversing valves, pushing the piston rods to move. The boom and bucket cylinders 92 and 93 then move, closing the valve stems. When the motion operating mechanism 6 remains stationary, the controller 4 continuously outputs pulse equivalent signals to drive the stepper motors, causing the cylinders to continuously extend or retract. When the motion operating mechanism 6 returns to center, the stepper motors no longer receive pulse signals, the servo reversing valves close, and the cylinders stop moving.

[0044] Optionally, the steering mechanism includes a steering cylinder 91 comprised of a digital cylinder. 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 based on the steering electrical signal. Using a digital cylinder for the steering cylinder 91 also enables precise steering control. In other embodiments, the steering mechanism may also comprise a steering cylinder, a flow amplification valve for controlling the extension and retraction of the steering cylinder, and a steering gear for controlling the flow amplification valve. To obtain the steering electrical signal, a speed sensor may be provided to detect the speed of the steering gear.

[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 the throttle hole. Its valve stem slides under the pressure of the hydraulic control end to adjust the valve port opening 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 power to the three-position, two-way solenoid valve 32 is de-energized, the oil circuit between its oil inlet and oil outlet is blocked. Pressurized oil from the first working oil port of the hydraulically controlled three-position, three-way valve 31 enters the hydraulic control end of the hydraulically controlled three-position, three-way valve 31 through the throttle orifice, building pressure there. The valve stem of the hydraulically controlled three-position, three-way valve 31, under the action of the hydraulic oil at the hydraulic control end, moves toward the spring chamber to its limit position. At this point, the hydraulically controlled three-position, three-way valve 31 is in the right position, the oil circuit between its oil inlet and the first working oil port is open, and the valve opening is minimized. The minimized valve opening between the oil inlet and the first working oil port allows pressurized oil to flow out of the first working oil port, allowing pressurized oil to flow through the throttle orifice to the hydraulic control end of the hydraulically controlled three-position, three-way valve. The oil circuit between the oil inlet and the second working oil port is open, and the valve opening is maximized, allowing the steering pump output flow to merge with the working pump and be supplied to the boom and bucket cylinders.

[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 realizing 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 a displacement adjustment electronic control terminal 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 rate so that its output flow rate meets 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 needed, thereby adjusting its output flow.

[0054] Optionally, the loader's hydraulic system may further include a first shut-off valve 71, a two-position, two-way solenoid valve with its oil inlet connected to the pump port of the steering pump 21 and its oil outlet connected to the hydraulic oil tank 1. A throttle valve for establishing back pressure is provided in the oil path between the oil inlet and the hydraulic oil tank. When the steering pump 21 enters standby mode, its displacement is at its minimum. At this point, the first shut-off valve 71 is opened, further reducing the pressure at the pump port of the steering pump 21, achieving low-pressure unloading and further reducing the energy consumed by the steering pump 21 during standby mode.

[0055] Similarly, the loader's hydraulic system may also include a second shut-off valve 72; this is a two-position, two-way solenoid valve with its oil inlet connected to the pump port of the working pump 22 and its oil outlet connected to the hydraulic oil tank 1. A throttle valve is provided in the oil path between the oil inlet and the hydraulic oil tank to establish back pressure. When the working pump 22 enters standby mode, its displacement is at its minimum. At this point, the second shut-off valve 72 opens, further reducing the pressure at the pump port of the working pump 22, achieving low-pressure unloading and further reducing the energy consumed by the working pump during standby.

[0056] Optionally, the loader hydraulic system may further include a first relief valve 81, the oil inlet of which is connected to the pump port of the steering pump 21, and the oil outlet of which is in communication with the hydraulic oil tank 1. The first relief valve 81 opens to relieve load when the pressure at the pump port of the steering pump 21 reaches its relief set pressure. It serves as a safety valve to prevent excessive pressure caused by excessive load.

[0057] Similarly, the loader hydraulic system may also include a second relief valve 82; its oil inlet is connected to the pump port of the working pump, and its oil outlet is connected to the hydraulic oil tank 1. The second relief valve 82 opens to relieve the load when the pressure at the pump port of the working pump 22 reaches its set relief pressure. It acts 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, wherein 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 have other structural forms. For example, it can include a steering gear, a steering gear that drives the steering gear, and a speed sensor for detecting the steering gear speed, the speed sensor being electrically connected to the controller. The speed sensor detects the steering gear speed and converts it into an electrical steering signal, which is transmitted to the controller. The controller then controls the steering based on the electrical signal. The steering operating mechanism is a remote control receiver electrically connected to the controller for receiving operating signals. The loader can be a remote control device, with its onboard remote control receiver receiving the remote control signal and transmitting the steering signal to the controller, which then controls the loader's steering.

[0060] Optionally, the motion operating mechanism 6 is an electrically controlled pilot handle electrically connected to the controller. When the electrically controlled pilot handle is swung, it generates corresponding boom motion signals and bucket motion electrical signals based on the direction and amplitude of its swing, and transmits these signals to the controller. The motion operating mechanism can also be a remote control receiver electrically connected to the controller for receiving the operation signals. The loader can be a remote control device, with its onboard remote control receiver receiving the remote control signals and transmitting the boom motion signals and bucket motion signals to the controller, which then controls the operation of the loader's working device.

[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 entire machine is started and there is no movement, 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 this 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 the 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 shut-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 entire 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 to a certain flow range (e.g., a maximum of no more than 100 L / 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 steering stops, controller 4 first stops sending the stepper motor signal to steering cylinder 91, then gradually reduces the displacement of steering pump 21 to its minimum value, and simultaneously de-energizes first shut-off valve 71. At the moment of steering stop, the valve stem of steering cylinder 91 is closed by the movement of the cylinder, and steering cylinder 91 stops moving.

[0070] When the operating mechanism 6 is manipulated with a small amplitude to make the working device move independently (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 shut-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 independently 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 converging control valve 3 is energized, causing it to switch to the left position. The pressure relief oil circuit of the hydraulically controlled three-position three-way valve 31 is cut off, and the pressure of the steering pump 21 acts on the hydraulically controlled three-position three-way valve 31 to overcome the spring force, causing the hydraulically controlled three-position three-way valve 31 to operate in the right position, and the steering pump 22 begins to supply oil to the working system. At the same time, the controller 4 adds two output signals: the first controls the first shut-off valve 71 to switch to the right position within a certain period of time, and the steering pump 21 also begins to supply oil to the boom cylinder 92; the second controls the steering pump 21 to increase to its 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 is moved 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 hydraulic control 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 all 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 bucket cylinder are digital cylinders that include 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, for supplying working pressure oil to the boom cylinder and the bucket cylinder; A steering pump is connected to a merging control valve, wherein a first working oil port of the merging control valve is connected to the 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 and configured to generate an action electrical signal, wherein the action electrical signal includes an arm action electrical signal for extension and retraction of the arm cylinder and a bucket action electrical signal for extension and retraction of the bucket cylinder; The confluence control valve is electrically connected to the controller, and the controller outputs flow distribution control current to the confluence control valve and pulse equivalent signals to the stepper motors of the boom cylinder and 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 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.

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 a first working oil port and a second working oil port. The hydraulic control end is connected to the first working oil port through a throttle hole, and its valve stem slides under the pressure of the hydraulic control end to adjust the valve port opening between the oil inlet and the first working oil port and the second working oil port respectively; The electrical 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 is a variable displacement pump with adjustable displacement and a displacement adjustment electronic control end electrically connected to the controller.

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

7. The loader hydraulic system according to claim 5, characterized in that: The system further includes 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 gear 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 that drives 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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