Loader and hydraulic system thereof

Abstract

The invention relates to a loader, in particular to a loader and a hydraulic system thereof, and aims to solve the problem that an existing hydraulic system of the loader is insufficient in refined operation, the hydraulic system of the loader comprises a controller, a working hydraulic system and a steering hydraulic system, and a steering oil cylinder, a movable arm oil cylinder and a bucket oil cylinder are all digital oil cylinders; the working pump is connected with the movable arm oil cylinder and the bucket oil cylinder, and the steering pump is connected with the steering oil cylinder; the action operation mechanism and the steering operation mechanism are electrically connected with the controller, and the stepping motor of each oil cylinder is electrically connected with the controller. The controller outputs pulse equivalent signals to a stepping motor of the steering oil cylinder according to the steering electric signals and outputs pulse equivalent signals to stepping motors of the movable arm oil cylinder and the bucket oil cylinder according to the action electric signals. According to the hydraulic system, the movable arm oil cylinder, the bucket oil cylinder and the steering oil cylinder are in the form of 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 for achieving the purpose of the present invention is: a loader hydraulic system, including a controller, a working hydraulic system, and a steering hydraulic system.

[0006] In the working hydraulic system: the boom cylinder and the bucket cylinder are both digital cylinders comprising a stepper motor and a servo reversing valve; a working pump is connected to the boom cylinder and the bucket cylinder; an action operating mechanism for generating an action electrical signal is electrically connected to a controller, and the action electrical signal includes a boom action electrical signal for controlling the extension and retraction of the boom cylinder and a bucket action electrical signal for controlling the extension and retraction of the bucket cylinder; the stepper motors of the boom cylinder and the bucket cylinder are electrically connected to the controller.

[0007] In the steering hydraulic system, the steering cylinder is a digital cylinder including a stepper motor and a servo reversing valve, a steering pump is connected to the steering cylinder; a steering operating mechanism for generating a steering electrical signal is electrically connected to the controller; and a stepper motor of the steering cylinder is electrically connected to the controller.

[0008] The controller outputs a pulse equivalent signal to the stepper motor of the steering cylinder according to the steering electrical signal, and outputs a pulse equivalent signal to the stepper motors of the boom cylinder and the bucket cylinder according to the action electrical signal.

[0009] 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.

[0010] 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;

[0011] 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;

[0012] 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;

[0013] 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.

[0014] In the loader hydraulic system of the present invention, the system further comprises a first overflow valve and / or a second overflow valve;

[0015] 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;

[0016] 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.

[0017] In the loader hydraulic system of the present invention, the steering operating mechanism includes a steering gear and a speed sensor for detecting the speed of the steering gear, and the speed sensor is electrically connected to the controller. Further, the steering operating mechanism also includes a steering gear driven by the steering gear, the oil inlet of the steering gear is connected to the pump port of the steering pump through a pressure reducing valve, the left and right steering pilot output ports of the steering gear are each connected to a one-way valve, and the oil outlet ends of the two one-way valves are connected to the hydraulic oil tank through a relief valve.

[0018] In the loader hydraulic system of the present invention, the steering operating mechanism may also include a steering motor and a steering machine that rotates the steering motor, and the steering motor is electrically connected to the controller.

[0019] In the loader hydraulic system of the present invention, the action operating mechanism is an electrically controlled pilot handle electrically connected to the controller.

[0020] In the loader hydraulic system of the present invention, the motion operating mechanism and the steering operating mechanism may also be remote control receivers electrically connected to the controller for receiving operating signals.

[0021] The technical solution of the present invention to achieve its purpose is: a loader having the above-mentioned loader hydraulic system.

[0022] 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

[0023] Figure 1 It is a schematic diagram of the hydraulic system of the loader of the present invention.

[0024] Parts names and serial numbers in the figure:

[0025] Hydraulic oil tank 1, steering pump 21, working pump 22, controller 4, steering gear 51, speed sensor 52, relief valve 53, pressure reducing valve 54, steering gear 55, check valve 56, action operating mechanism 6, first cut-off valve 71, second cut-off valve 72, first relief valve 81, second relief valve 82, steering cylinder 91, boom cylinder 92, bucket cylinder 93. DETAILED DESCRIPTION

[0026] The specific implementation scheme is described below with reference to the accompanying drawings.

[0027] like Figure 1 As shown, the loader hydraulic system includes a controller 4, a working hydraulic system, and a steering hydraulic system.

[0028] In the working hydraulic system: the boom cylinder 92 and the bucket cylinder 93 are both digital cylinders including a stepper motor and a servo reversing valve. The working pump 22 is connected to the boom cylinder 92 and the bucket cylinder 93 to supply them with pressure oil for the actuation of the working device; the action operating mechanism 6 for generating an action electric signal is electrically connected to the controller 4, and the action electric signal includes an arm action electric signal for controlling the extension and retraction of the boom cylinder 92 and a bucket action electric signal for controlling the extension and retraction of the bucket cylinder 93; the stepper motors of the boom cylinder 92 and the bucket cylinder 93 are electrically connected to the controller 4.

[0029] In the steering hydraulic system, the steering cylinder 91 is a digital cylinder including a stepper motor and a servo reversing valve, the steering pump 21 is connected to the steering cylinder 91; the steering operating mechanism for generating a steering electrical signal is electrically connected to the controller 4; and the stepper motor of the steering cylinder 91 is electrically connected to the controller.

[0030] The controller 4 outputs a pulse equivalent signal to the stepper motor of the steering cylinder 91 according to the steering electrical signal, and outputs a pulse equivalent signal to the stepper motors of the boom cylinder 92 and the bucket cylinder 93 according to the motion electrical signal.

[0031] In this embodiment, the steering cylinder 91, 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.

[0032] In this embodiment, the working hydraulic system and steering hydraulic system of the loader hydraulic system are both 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 92 and the bucket cylinder 93, and the stepper motor drives the valve stem of the servo reversing valve to open; the working pump 22 outputs flow and enters 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. Similarly, the steering mechanism inputs a signal to the controller 4, and the controller 4 outputs a corresponding pulse equivalent signal to the stepper motor of the steering cylinder 91, and the stepper motor drives the servo reversing valve stem to open; the steering pump 21 outputs flow and enters the steering cylinder 91 through the servo reversing valve to drive the piston rod to move, and the steering cylinder 91 closes the valve stem after movement. When the steering mechanism 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 steering mechanism returns to the center, there is no pulse signal input to the stepper motor, the servo reversing valve is closed, and the cylinder stops moving.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Optionally, the steering operating mechanism includes a steering gear 55 and a speed sensor 52 for detecting the speed of the steering gear, and the speed sensor 52 is electrically connected to the controller 4. When the driver turns the steering wheel of the steering gear 55, the steering gear 55 rotates, and the speed sensor 52 detects its speed and converts it into a steering electrical signal to transmit to the controller 4, and the controller 4 controls the steering cylinder 91 and the steering pump 21 according to the steering electrical signal. Further, the steering operating mechanism may also include a steering gear 51 driven by the steering gear 55, the oil inlet of the steering gear 51 is connected to the pump port of the steering pump 21 through a pressure reducing valve 54, and the left and right steering pilot output ports of the steering gear 51 are each connected to a one-way valve 56, and the oil outlet ends of the two one-way valves 56 are connected to the hydraulic oil tank 1 through an overflow valve 53. In this solution, the one-way valve 56 and the overflow valve 53 connected to the steering pilot output port of the steering gear 51 act as simulated flow amplification valves. When the driver turns the steering wheel of the steering gear 55, the steering gear 55 drives the steering gear 51 to rotate and output the steering pilot pressure oil, so that the steering operation experience of the driver when operating the steering is the same as the steering operation experience of a loader controlled by a traditional steering gear.

[0040] In other embodiments, the steering operating mechanism may also include 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.

[0041] Optionally, the action operating mechanism 6 is an electrically controlled pilot handle electrically connected to the controller 4. When the electrically controlled pilot handle is swung, it generates corresponding boom action signals and bucket action electrical signals according to its own swing direction and amplitude and transmits them to the controller.

[0042] In other embodiments, the steering operating mechanism and the motion operating mechanism 6 may be the same set of equipment, which is a remote control receiver electrically connected to the controller 4 for receiving operation signals. The loader may be a remote control operating device, and its on-board remote control receiver receives remote control signals and transmits the boom motion electrical signals, bucket motion electrical signals, and steering electrical signals therein to the controller, which controls the working device and steering cylinder motion of the loader.

[0043] This embodiment also provides a loader having the aforementioned loader hydraulic system.

[0044] 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.

[0045] 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.

[0046] When the machine is turning,

[0047] The steering operating mechanism 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.

[0048] The output flow of the steering pump 21 is associated with the steering electrical signal of the steering operating mechanism. 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 (such as a maximum of no more than 100L / min).

[0049] The steering operating mechanism 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.

[0050] 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.

[0051] When the action operating mechanism 6 is manipulated to move the working device (the boom cylinder or bucket cylinder is extended or retracted, and the boom lifting is taken as an example below), 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 desired displacement, and the output flow of the working pump 22 enters the boom cylinder through the servo valve to achieve the extension or retraction of the boom cylinder.

Claims

1. A loader hydraulic system, comprising a controller, a working hydraulic system, and a steering hydraulic system, characterized in that: In the working hydraulic system: the boom cylinder and the bucket cylinder are both digital cylinders including a stepper motor and a servo reversing valve; the working pump is connected to the boom cylinder and the bucket cylinder; the action operating mechanism for generating an action electric signal is electrically connected to a controller, and the action electric signal includes an arm action electric signal for controlling the extension and retraction of the boom cylinder and a bucket action electric signal for controlling the extension and retraction of the bucket cylinder; the stepper motors of the boom cylinder and the bucket cylinder are electrically connected to the controller; In the steering hydraulic system, the steering cylinder is a digital cylinder including a stepper motor and a servo reversing valve, the steering pump is connected to the steering cylinder; the steering operating mechanism for generating a steering electrical signal is electrically connected to the controller; 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, and outputs a pulse equivalent signal to the stepper motors of the boom cylinder and the bucket cylinder according to the action electrical signal.

2. The loader hydraulic system according to claim 1, characterized in that: 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.

3. 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.

4. The loader hydraulic system according to claim 3, 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.

5. The loader hydraulic system according to claim 1, characterized in that: The steering operating mechanism includes a steering gear and a rotation speed sensor for detecting the rotation speed of the steering gear, and the rotation speed sensor is electrically connected to the controller.

6. The loader hydraulic system according to claim 5, characterized in that: The steering operating mechanism also includes a steering gear driven by a steering machine, the oil inlet of the steering gear is connected to the pump port of the steering pump via a pressure reducing valve, the left and right steering pilot output ports of the steering gear are each connected to a one-way valve, and the oil outlet ends of the two one-way valves are connected to the hydraulic oil tank via an overflow valve.

7. The loader hydraulic system according to claim 1, characterized in that: The steering operating mechanism comprises a steering motor and a steering machine for rotating the steering motor, and the steering motor is electrically connected to the controller.

8. The loader hydraulic system according to claim 1, characterized in that: The action operating mechanism is an electrically controlled pilot handle electrically connected to the controller.

9. The loader hydraulic system according to claim 1, characterized in that: The motion operating mechanism and the steering operating mechanism are remote control receivers electrically connected to the controller for receiving operating signals.

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

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