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 refined operation, and the hydraulic system of the loading machine comprises a controller, a working hydraulic system and a steering hydraulic system. Wherein the steering oil cylinder, the movable arm oil cylinder and the bucket oil cylinder are 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 utility model, the movable arm oil cylinder, the bucket oil cylinder and the steering oil cylinder are digital oil cylinders 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, comprising 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 containing 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 electrical signal is electrically connected to the 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 both electrically connected to the controller.

[0007] In the steering hydraulic system, the steering cylinder is a digital cylinder containing 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; and the 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 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.

[0010] 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;

[0011] 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;

[0012] 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;

[0013] 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.

[0014] 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;

[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 hydraulic system of a loader according to the present invention, the steering mechanism includes a steering gear and a speed sensor for detecting the speed of the steering gear, the speed sensor being electrically connected to the controller. Furthermore, the steering mechanism includes a steering gear driven by the steering gear, the oil inlet of the steering gear being 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 being each connected to a check valve, and the oil outlets of the two check valves being connected to the hydraulic oil tank via a relief valve.

[0018] In the hydraulic system of the loader 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 hydraulic system of the loader of the utility model, the action operating mechanism is an electrically controlled pilot handle electrically connected to the controller.

[0020] In the hydraulic system of the loader 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 for achieving the purpose of the utility model 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 the controller to achieve precise control. BRIEF DESCRIPTION OF THE DRAWINGS

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

[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, one-way valve 56, 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

[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, both the boom cylinder 92 and the bucket cylinder 93 are digital cylinders that include stepper motors and servo reversing valves. A working pump 22 is connected to the boom cylinder 92 and bucket cylinder 93, supplying them with pressurized oil for operating the working mechanism. The motion operating mechanism 6, which generates electrical motion signals, is electrically connected to the controller 4. These signals include boom motion signals for controlling the extension and retraction of the boom cylinder 92 and bucket motion signals for controlling the extension and retraction of the bucket cylinder 93. The stepper motors in each boom cylinder 92 and bucket cylinder 93 are also electrically connected to the controller 4.

[0029] In the steering hydraulic system, the steering cylinder 91 is a digital cylinder containing 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 stepping motor of the steering cylinder 91 according to the steering electrical signal, and outputs a pulse equivalent signal to the stepping 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, 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.

[0032] In this embodiment, both the working hydraulic system and the steering hydraulic system of the loader's hydraulic system are closed-loop systems: the motion operating mechanism 6 inputs signals to the controller 4, which then outputs corresponding pulse equivalent signals to the stepper motors of the boom cylinder 92 and bucket cylinder 93. The stepper motors then push the servo reversing valve stems to open. The working pump 22 outputs flow, which enters the cylinders through the servo reversing valves to move the piston rods. After the boom cylinder 92 and bucket cylinder 93 move, the valve stems are closed. 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. Similarly, the steering mechanism inputs signals to controller 4, which in turn outputs corresponding pulse equivalent signals to the stepper motor in steering cylinder 91. This signals the servo reversing valve stem to open. The output of steering pump 21 flows through the servo reversing valve into steering cylinder 91, pushing the piston rod in motion. This movement of steering cylinder 91 then closes the valve stem. When the steering mechanism remains stationary, controller 4 continuously outputs pulse equivalent signals to drive the stepper motor, causing the cylinder to continuously extend or retract. When the steering mechanism returns to center, the stepper motor loses its pulse signal input, the servo reversing valve closes, and the cylinder stops moving.

[0033] 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.

[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 needed, thereby adjusting its output flow.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] Optionally, the steering mechanism includes a steering gear 55 and a speed sensor 52 for detecting the steering gear rotational speed. 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. The speed sensor 52 detects the rotational speed and converts it into a steering electrical signal, which is transmitted to the controller 4. The controller 4 controls the steering cylinder 91 and the steering pump 21 based on the steering electrical signal. Furthermore, the steering 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 via a pressure reducing valve 54. The left and right steering pilot output ports of the steering gear 51 are each connected to a one-way valve 56. The oil outlets of the two one-way valves 56 are connected to the hydraulic oil tank 1 via a relief 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 device, which is a remote control receiver electrically connected to the controller 4 for receiving operating signals. The loader may be a remote control operating device, wherein the onboard remote control receiver receives the 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 motion of the loader's working device and steering cylinder.

[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 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.

[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 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.

[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 to a certain flow range (e.g., a maximum of no more than 100 L / 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 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.

[0051] When the action operating mechanism 6 is manipulated to move the working device (the boom cylinder or bucket cylinder is extended or retracted, with the boom lifting and lowering being used 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 begins to supply oil to the boom cylinder 92; the third signal controls the working pump 22 to increase its displacement to the desired level, and the output flow of the working pump 22 enters the boom cylinder through the servo valve to achieve 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; 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, the action electrical signal including an arm 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 each 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 containing 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 adjustment electronic control end electrically connected to the controller.

3. 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.

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

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. 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 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 an overflow valve.

7. The loader hydraulic system according to claim 1, 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.

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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