Grader variable float device and control method

Abstract

This application relates to the field of engineering machinery technology, specifically to a variable floating device and control method for a grader blade. The device includes: a left variable floating valve group connected between the left lifting cylinder and the hydraulic return line; and a right variable floating valve group connected between the right lifting cylinder and the hydraulic return line. Each variable floating valve group includes: at least one solenoid directional valve, used to connect the large chamber of the corresponding lifting cylinder to the hydraulic return line when energized; and an electro-proportional relief valve, whose inlet is connected to the small chamber of the corresponding lifting cylinder and whose outlet is connected to the hydraulic return line. The electro-proportional relief valve provides steplessly adjustable back pressure to the small chamber of the corresponding lifting cylinder according to the received control signal, to offset part of the blade's self-weight, thereby adjusting the force exerted by the blade on the ground. Utilizing its back pressure adjustment characteristic, stepless adjustment of the force exerted by the blade on the ground is achieved, and the floating force can be precisely controlled according to different working conditions.

Description

Technical Field

[0001] This application relates to the field of engineering machinery technology, specifically to a variable floating device and control method for a grader blade. Background Technology

[0002] A grader is a type of construction machinery that uses a blade as its main working device. The height of the blade is adjusted by lifting left and right hydraulic cylinders. It is widely used in roadbed leveling, slope trimming, and snow removal. In special working conditions such as snow removal, leveling, and ditch clearing, the blade is required to automatically rise and fall according to the undulations of the ground, i.e., it must have a "floating" function to avoid rigid impact between the blade and the ground, thus protecting the road surface and the working device.

[0003] Traditional blade floating functionality is typically achieved through a hydraulic system. Its basic principle involves simultaneously connecting both the large and small chambers of the lifting cylinder to the return oil circuit, thus removing the hydraulic locking force at both ends of the cylinder. The blade then relies solely on its own weight to maintain contact with the ground, moving freely up and down with the terrain's undulations. This floating method has a simple structure and can meet basic requirements in conventional land leveling operations.

[0004] However, with the continuous expansion of grader applications, especially in special working conditions such as snow removal, mine road maintenance, and loosening and leveling of ground, the limitations of traditional floating mechanisms are becoming increasingly apparent. Specifically, when working on loose ground, the blade tends to sink deeper and deeper under its own weight, leading to a sharp increase in travel resistance, and in severe cases, even preventing normal operation. When clearing snow on hard surfaces, the blade exerts excessive impact force on the ground, easily causing road damage, while also posing a high risk of damage to the blade itself. The root cause of these problems lies in the fact that the force exerted by the blade on the ground under traditional floating mechanisms remains constant, depending only on the blade's own weight, and cannot be adaptively adjusted according to ground conditions.

[0005] Therefore, developing a floating device that can steplessly adjust the force of the blade on the ground according to working conditions has become an urgent technical problem to be solved in the field of grader technology. Summary of the Invention

[0006] This invention provides a variable floating device and control method for a grader blade, which aims to control the force exerted by the blade on the ground by providing steplessly adjustable back pressure to the small chamber of the lifting cylinder, thus adapting to different working conditions.

[0007] In a first aspect, the present invention provides a variable floating device for a grader, applied to a grader blade floating control system having a left lifting cylinder and a right lifting cylinder, wherein the large chambers of the left and right lifting cylinders are respectively connected to a main valve via a balance valve, and the device includes: A left variable floating valve assembly is connected between the left lifting cylinder and the hydraulic return circuit; The right variable floating valve assembly is connected between the right lifting cylinder and the hydraulic return circuit; Each variable floating valve group includes: At least one solenoid directional valve is used to connect the large chamber of the corresponding lifting cylinder to the hydraulic return circuit when energized. An electro-proportional relief valve has its inlet connected to the small chamber of the corresponding lifting cylinder and its outlet connected to the hydraulic return circuit. The electro-proportional relief valve is used to provide steplessly adjustable back pressure to the small chamber of the corresponding lifting cylinder according to the received control electrical signal, so as to offset part of the blade's self-weight and thus adjust the force of the blade on the ground.

[0008] By installing an electro-proportional relief valve on the return oil line of the lifting cylinder's small chamber, and utilizing its back pressure adjustment characteristics, stepless adjustment of the blade's force on the ground is achieved. The floating force can be precisely controlled according to different working conditions (snow removal, leveling, ditch clearing, etc.), filling the gap in traditional floating devices that only offer a single fully floating mode. Only a variable floating valve assembly needs to be added to the existing hydraulic system; there is no need to replace core hydraulic components such as the main valve and balance valve, resulting in low modification costs. It retains the traditional floating function while adding an adjustable floating force function, enabling the grader to adapt to various working scenarios from loose ground to hard surfaces.

[0009] As a preferred embodiment of the present invention, it further includes a controller, which is electrically connected to the electro-proportional relief valve. The controller is configured to receive a floating force adjustment signal and output a control electrical signal to the electro-proportional relief valve according to the floating force adjustment signal.

[0010] A controller electrically connected to the electro-proportional relief valve was added. The controller receives the floating force adjustment signal and converts it into a control signal for the electro-proportional relief valve, realizing precise electronic control of back pressure and replacing the purely manual hydraulic adjustment method. The controller can stabilize the adjustment signal, avoiding errors and fluctuations caused by manual adjustment and ensuring the stability of the blade's force on the ground. At the same time, it lays the hardware foundation for the subsequent integration of more intelligent control logic and the realization of automated adjustment, improving the intelligence level and ease of operation of the device.

[0011] As a preferred embodiment of the technical solution of the present invention, the electromagnetic reversing valve includes a first electromagnetic reversing valve and a second electromagnetic reversing valve. The large chamber of the lifting cylinder is connected to the hydraulic return circuit in sequence through the second electromagnetic reversing valve and the first electromagnetic reversing valve. The small chamber of the lifting cylinder is connected to the hydraulic return circuit in sequence through the electro-proportional relief valve, the second solenoid directional valve and the first solenoid directional valve. The electro-proportional relief valve and the first electromagnetic directional valve are connected in series on the oil line from the small cavity of the corresponding lifting cylinder to the hydraulic return oil line.

[0012] The electromagnetic directional valves are configured as a combination of the first and second electromagnetic directional valves, and dedicated oil circuits are planned from the large and small chambers of the lifting cylinder to the hydraulic return circuit. This allows the on / off of the oil circuits in the large and small chambers of the cylinder to be controlled collaboratively by the dual electromagnetic directional valves, improving the reliability of oil circuit on / off and effectively avoiding oil circuit runaway caused by the failure of a single directional valve. The electro-proportional relief valve and the first electromagnetic directional valve are connected in series on the small chamber oil circuit, so that the back pressure regulation only acts on the small chamber return path. The oil circuit logic is clear, and it can accurately control the application and regulation of back pressure, avoiding interference with the large chamber oil circuit. The series oil circuit structure makes the internal components of the valve group more compact, reduces the risk of oil circuit leakage, and improves the sealing performance and operational stability of the hydraulic system.

[0013] As a preferred embodiment of the technical solution of the present invention, the oil inlets of the left variable floating valve group and the right variable floating valve group are connected in parallel to the hydraulic pipeline between the corresponding balance valve and the corresponding lifting cylinder, and their oil outlets are connected to the hydraulic return oil circuit, forming an independently installed modular valve group.

[0014] The left and right variable floating valve assemblies are designed as modular valve assemblies installed in parallel between the balance valve and the lifting cylinder. This eliminates the need to disassemble or modify the core connection structure of the original balance valve, main valve, and hydraulic pipeline of the grader, significantly reducing the difficulty of installation and modification. It is compatible with the blade floating control system of different grader models, offering strong versatility. The modular valve assembly structure makes the maintenance and replacement of the device more convenient. The valve assembly can be disassembled and maintained individually without affecting the normal operation of the original hydraulic system of the grader, reducing equipment maintenance costs and downtime. The parallel connection method allows the valve assembly to intervene only in the return oil logic of the lifting cylinder without changing the power supply of the original hydraulic system, ensuring the stability of the original operating functions of the grader.

[0015] As a preferred embodiment of the technical solution of the present invention, the electromagnetic reversing valve is a two-position two-way electromagnetic reversing valve, which disconnects the connection between the lifting cylinder and the hydraulic return circuit in the de-energized state. The electro-proportional relief valve is a normally closed electro-proportional relief valve, which cuts off the connection between the lifting cylinder small chamber and the hydraulic return circuit when the power is off.

[0016] The solenoid directional valve is designed as a two-position, two-way type. In the event of power failure, it directly cuts off the connection between the lifting cylinder and the hydraulic return circuit, achieving mechanical locking of the blade. The locking reliability is high, preventing accidental movement of the blade due to oil circuit leakage. The normally closed electro-proportional relief valve cuts off the connection between the small chamber and the return circuit in the event of power failure, forming a double oil circuit cutoff protection with the solenoid directional valve. This further enhances the safety of the hydraulic system and prevents equipment or road damage caused by the blade falling due to pressure leakage in the small chamber of the cylinder during non-operational conditions. Both the two-position, two-way solenoid directional valve and the normally closed electro-proportional relief valve are mature hydraulic components with low procurement costs and strong adaptability, reducing the overall manufacturing cost of the device and the difficulty of fault repair.

[0017] Secondly, the present invention also provides a control method for a grader using the variable floating device as described in the first aspect, comprising the following steps: Read the mode selection switch signal on the operation panel to determine the target working mode; If the target working mode is the non-floating mode, then output a power failure signal to all solenoid directional valves, cut off the connection between all lifting cylinders and hydraulic return circuit, and put the blade in the locked state. If the target operating mode is floating mode, then according to the selected specific floating mode, an electrical signal is output to the corresponding solenoid directional valve, so that the large chamber of the corresponding lifting cylinder is connected to the hydraulic return circuit, and the small chamber is connected to the hydraulic return circuit through the electro-proportional relief valve, thus entering the floating state; in the floating state, the following parallel operations are performed: Read the signal from the left floating force adjustment knob, and output the corresponding control signal to the left electro-proportional overflow valve according to the signal, so that it provides steplessly adjustable back pressure to the small chamber of the left lifting cylinder to offset part of the blade's own weight, thereby realizing stepless adjustment of the blade's force on the ground; The signal from the right floating force adjustment knob is read, and a corresponding control signal is output to the right electro-proportional overflow valve based on the signal, so that it provides steplessly adjustable back pressure to the small chamber of the right lifting cylinder to offset part of the blade's own weight, thereby realizing stepless adjustment of the blade's force on the ground.

[0018] Automatic switching between non-floating and floating modes is achieved by reading the mode selection switch signal. The operation logic is clear, eliminating the need for complex manual hydraulic adjustments and improving the convenience of operation. In non-floating mode, all oil circuits are cut off by a power failure signal to reliably lock the blade, meeting the blade fixation requirements of graders during site transfers and non-operational states. In floating mode, the left and right electro-proportional relief valves are independently controlled according to the signal, enabling stepless adjustment of the back pressure on the left and right sides. This adapts to complex working conditions with uneven road surfaces, allowing the blade to adaptively conform to the ground on both sides, improving the smoothness of the work surface. The parallel execution of the left and right adjustment logic ensures the independence and synchronicity of the force adjustment on both sides, avoiding interference from one side adjustment to the other.

[0019] As a preferred embodiment of the technical solution of the present invention, the floating mode includes a dual-cylinder floating mode and a single-cylinder floating mode; Dual-cylinder floating mode control steps: The first and second solenoid directional valves in the left variable floating valve group output electrical signals, so that the large chamber of the left lifting cylinder is connected to the hydraulic return circuit through the second and first solenoid directional valves in sequence, and the small chamber of the left lifting cylinder is connected to the hydraulic return circuit through the electro-proportional relief valve, the second solenoid directional valve and the first solenoid directional valve in sequence. The first and second solenoid directional valves in the right-side variable floating valve group output electrical signals, so that the large chamber of the right lifting cylinder is connected to the hydraulic return circuit through the second and first solenoid directional valves in sequence, and the small chamber of the right lifting cylinder is connected to the hydraulic return circuit through the electro-proportional relief valve, the second solenoid directional valve and the first solenoid directional valve in sequence. Single-cylinder floating mode control steps: When the left single-cylinder floating is selected, the first solenoid directional valve and the second solenoid directional valve in the left variable floating valve group are output with an energized signal, and the first solenoid directional valve and the second solenoid directional valve in the right variable floating valve group are output with a de-energized signal. When the right single-cylinder floating mode is selected, the first and second solenoid directional valves in the right variable floating valve group are output with an energized signal, and the first and second solenoid directional valves in the left variable floating valve group are output with a de-energized signal.

[0020] The floating mode is further subdivided into dual-cylinder and single-cylinder floating modes, enriching the device's operating mode options and adapting to different operational needs of the grader: the dual-cylinder floating mode meets routine operations such as leveling the entire road surface and snow removal, allowing the blade to adapt to the ground as a whole; the single-cylinder floating mode is suitable for special working conditions such as obstacles on one side of the road or slope trimming on one side, allowing independent control of one side of the blade to float while the other side is locked, improving the flexibility and specificity of the operation; in the single-cylinder floating mode, precise switching of single-side floating is achieved through independent energization / de-energization control of the solenoid directional valves of the left and right valve groups, with no action interference between valve groups, simple and reliable control logic, and operators can quickly switch modes through the mode switch, reducing the difficulty of operation.

[0021] As a preferred embodiment of the technical solution of the present invention, it includes an initial buoyancy calibration step, which is performed after first use or maintenance: a) Position the grader on a horizontal reference surface, raise the blade and level it to the preset height; b) Activate the variable floating valve group on one side and set the input electrical signal of the electro-proportional relief valve on that side to the maximum value; c) Reduce the input electrical signal of the electro-proportional relief valve on this side according to the set step size, while monitoring the position of the piston rod of the lifting cylinder on this side; d) When the piston rod begins to move downwards, record the current electrical signal value as the baseline calibration value for that side; e) Repeat steps b) to d) to calibrate the other side; f) Store the basic calibration values ​​of the left and right sides in the controller to compensate for the control of the electro-proportional relief valve in actual operation, and ensure the consistency of the left and right floating forces.

[0022] The initial calibration procedure for the floating force is set up to perform basic calibration on the left and right lifting cylinders respectively. This effectively eliminates the problem of inconsistent floating forces between the left and right sides caused by cylinder manufacturing errors, differences in valve component performance, and different pipeline resistances. This ensures that the force exerted on the ground by both sides of the blade is uniform, improving the smoothness of the road surface. The basic calibration value is determined by monitoring the piston rod position and stored in the controller as a compensation basis, making subsequent back pressure adjustments more accurate and avoiding errors from manual experience adjustments. The calibration procedure can be performed after first use or maintenance, which can promptly correct performance deviations caused by component wear and pipeline maintenance, ensuring the stability and adjustment accuracy of the device in long-term operation. The calibration process is automated by adjusting the electrical signal by the controller according to the set step size, reducing the difficulty and error of manual calibration.

[0023] As a preferred embodiment of the technical solution of the present invention, it further includes an intelligent protection step: The controller acquires vehicle speed signals in real time. When the vehicle speed is detected to be higher than the preset safety threshold, the power supply to all solenoid directional valves is automatically cut off regardless of the floating mode selection switch status, causing the blade to exit the floating state and enter the locking mode.

[0024] An intelligent protection mechanism based on vehicle speed signals has been added, allowing the controller to monitor vehicle speed in real time and automatically cut off the power to the solenoid reversing valve when the speed exceeds the limit. This causes the blade to disengage from its floating position and lock, avoiding the safety hazards caused by blade floating at high speeds. It prevents the blade from violently shaking up and down due to ground bumps at high speeds, which could cause mechanical damage to the blade, hydraulic cylinder, and other components. It also prevents the floating blade from violently colliding with the ground, damaging the road surface, or causing the grader to become unstable. The intelligent protection logic is automatically triggered without manual intervention, improving the operational safety of the equipment. Even if the operator accidentally activates the floating mode at high speed, automatic protection is achieved, further ensuring the safety of the equipment, the road surface, and the operator.

[0025] As a preferred embodiment of the technical solution of the present invention, in the steps executed in parallel under floating conditions, the left floating force adjustment knob signal, the right floating force adjustment knob signal, and the control electrical signal of the electro-proportional overflow valve are inversely proportional: the larger the knob signal, the smaller the control electrical signal, the lower the back pressure, and the greater the force exerted by the blade on the ground; the smaller the knob signal, the larger the control electrical signal, the higher the back pressure, and the smaller the force exerted by the blade on the ground.

[0026] By setting the floating force adjustment knob signal and the electro-proportional overflow valve control signal to an inverse proportional relationship, the operator's adjustment operation becomes more intuitive: turning the knob up increases the force exerted by the blade on the ground, suitable for operations requiring greater force, such as road compaction and heavy snow removal; turning the knob down decreases the force, suitable for light-load operations on easily damaged surfaces such as cement and asphalt roads. This simple and easy-to-understand operation reduces operator training costs. The inverse proportional signal correspondence enables stepless and precise adjustment of the force. Operators can fine-tune the knob according to operational needs to achieve smooth changes in blade force, avoiding road damage or poor operational results caused by sudden changes in force. At the same time, the inverse proportional control logic is simple, and the controller can process signals quickly, improving the adjustment response speed and allowing the device to adapt to changes in operating conditions in real time.

[0027] As can be seen from the above technical solutions, this application has the following advantages: By setting independent left and right variable floating valve groups in the grader blade floating control system, the on / off control of the lifting cylinder large chamber and the hydraulic return oil circuit is realized by using electromagnetic reversing valves, and at the same time, the back pressure of the lifting cylinder small chamber is provided by the electro-proportional overflow valve, which can accurately offset part of the blade's own weight, realizing flexible and continuous adjustment of the blade's force on the ground, solving the problem of non-adjustable contact pressure and easy road surface damage when the traditional grader blade floats; it is suitable for working conditions with high requirements for road surface protection, such as road snow removal, allowing the blade to adaptively conform to the road surface according to the operation requirements, greatly reducing the risk of ground damage while ensuring the operation effect; the valve group only needs to be adapted and connected to the lifting cylinder oil circuit, without modifying the original hydraulic main circuit core structure of the grader, and has strong adaptability. Attached Figure Description

[0028] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a hydraulic schematic diagram of the present invention; Figure 2 This is a control framework diagram of the present invention; Figure 3This is a flowchart of the initial calibration process for the buoyancy force of the present invention.

[0030] In the diagram: 1-Main valve; 2-Left balance valve; 3-Left lifting cylinder; 4-Left variable floating valve assembly; 5-Right balance valve; 6-Right lifting cylinder; 7-Right variable floating valve assembly; 4.1 - Left first solenoid directional valve; 4.2 - Left second solenoid directional valve; 4.3 - Left proportional relief valve; 7.1 - Right first solenoid directional valve; 7.2 - Right second solenoid directional valve; 7.3 - Right electro-proportional relief valve. Detailed Implementation

[0031] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this application and in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0033] This invention provides a variable floating device and control method for a grader. By incorporating an electromagnetic reversing valve and an electro-proportional overflow valve, variable floating control of the blade is achieved, effectively reducing the force exerted by the blade on the ground. This is suitable for applications such as snow removal. The blade can adaptively conform to the road surface according to a set floating force, minimizing damage to the ground during operation. It should be noted that: Grader: A type of road construction machinery that uses a blade as its main component and is equipped with various other interchangeable working devices to complete land leveling and shaping operations.

[0034] Electromagnetic directional valve: A control element that uses electromagnetic force to drive the valve core to move, thereby changing the direction of fluid flow.

[0035] Electro-proportional relief valve: a hydraulic control valve that continuously and proportionally controls the pressure of a hydraulic system by inputting an electrical signal.

[0036] Floating blade: This refers to placing the hydraulic control system of the blade in the working device of construction machinery into a special state. In this state, the inlet and outlet oil circuits of the two chambers of the lifting hydraulic cylinder of the blade are connected to each other and connected to the hydraulic oil tank, so that the blade loses the hydraulic locking force in the vertical direction and can move freely up and down according to its own weight and the undulation of the ground.

[0037] like Figure 1 As shown, this embodiment of the invention provides a variable floating device for a grader, applied to a grader blade floating control system having a left lifting cylinder 3 and a right lifting cylinder 6. The large chamber of the left lifting cylinder 3 is connected to the main valve 1 through a left balance valve 2, and the large chamber of the right lifting cylinder 6 is connected to the main valve 1 through a right balance valve 5.

[0038] The device also includes a left variable float valve group 4 and a right variable float valve group 7: The left variable floating valve group 4 is connected in parallel to the hydraulic pipeline between the left balance valve 2 and the left lifting cylinder 3, specifically between the left lifting cylinder 3 and the hydraulic return line. The right variable floating valve group 7 is connected in parallel to the hydraulic pipeline between the right balance valve 5 and the right lifting cylinder 6, specifically between the right lifting cylinder 6 and the hydraulic return line.

[0039] Both the left variable floating valve group 4 and the right variable floating valve group 7 are independently integrated modular valve groups that can be installed in the existing grader hydraulic system without changing the original vehicle main valve and balance valve structure.

[0040] To achieve floating based on the above-mentioned device, the core is to connect both the large and small chambers of the left lifting cylinder 3 to the return oil circuit, thereby releasing the hydraulic lock-up state.

[0041] When the mode selection switch is turned on (e.g., left single-cylinder floating mode), the controller sends an energizing signal to the left first solenoid directional valve 4.1 and the left second solenoid directional valve 4.2, opening the oil circuit. At this time: Large cavity oil circuit: The oil from the large cavity of the left lifting cylinder 3 flows through the already activated left second solenoid directional valve 4.2, then through the already activated left first solenoid directional valve 4.1, and finally flows into the hydraulic return circuit (oil tank). At this point, the large cavity is no longer supported by oil pressure.

[0042] Small chamber oil circuit: Oil from the small chamber of the left lifting cylinder 3 → flows into the left electro-proportional relief valve 4.3 (at this time, the valve is controlled by current and is in a specific open state) → flows out and merges into the left second solenoid directional valve 4.2 → then passes through the left first solenoid directional valve 4.1 → and finally flows into the hydraulic return oil circuit.

[0043] Both the large and small chambers are vented with return oil. When the left lifting cylinder 3 loses its hydraulic locking force, the left side of the shovel can move freely in the vertical direction, thus achieving a floating state.

[0044] In a floating state, the blade descending solely under its own weight would damage the road surface or sink into soft ground. This application uses a left electro-proportional relief valve 4.3 to offset part of its own weight, thereby controlling the pressure of the blade on the ground.

[0045] The left electro-proportional relief valve 4.3 allows oil to pass through, but requires a certain oil pressure to open it. When the small chamber of the left lifting cylinder 3 needs to discharge oil (i.e., when the blade needs to descend), sufficient pressure must first be built up before this valve to push open the valve core and allow the oil to flow out. The pressure built up is called back pressure. The back pressure acts on the piston surface of the small chamber of the left lifting cylinder 3, generating an upward thrust. This upward thrust can precisely offset part of the downward weight of the blade.

[0046] In other words, the force exerted by the shovel on the ground = the weight of the shovel - the thrust generated by the back pressure of the small cavity.

[0047] The magnitude of this thrust is controlled by the left floating force adjustment knob in the cab. The knob signal is sent to the controller, which outputs a precise current signal to the left electro-proportional relief valve 4.3.

[0048] If the knob is turned down (in the hope that the blade will press lightly on the ground): the current increases → the back pressure set by the overflow valve increases → the thrust of the small chamber increases → more of its own weight is offset → the force of the blade on the ground decreases.

[0049] If the knob is turned up (in the expectation that the blade will press heavily on the ground): the current decreases → the back pressure set by the overflow valve decreases → the thrust of the small chamber decreases → less self-weight is offset → the force of the blade on the ground increases.

[0050] By adjusting the back pressure of the return oil circuit, this device achieves precise and stepless control of the grounding force of the blade during the floating process.

[0051] In some embodiments, the left variable float valve assembly 4 includes: Left first solenoid directional valve 4.1: is a two-position two-way solenoid directional valve; Left second solenoid directional valve 4.2: a two-position, two-way solenoid directional valve; Left electro-proportional relief valve 4.3: This is a normally closed electro-proportional relief valve.

[0052] The large-cavity oil port of the left lifting cylinder 3 is connected to the oil inlet of the left second solenoid directional valve 4.2; the oil outlet of the left second solenoid directional valve 4.2 is connected to the oil inlet of the left first solenoid directional valve 4.1; and the oil outlet of the left first solenoid directional valve 4.1 is connected to the hydraulic return oil circuit.

[0053] The small chamber port of the left lifting cylinder 3 is connected to the inlet port of the left electro-proportional relief valve 4.3; the outlet port of the left electro-proportional relief valve 4.3 is connected to the inlet port of the left second solenoid directional valve 4.2 (connected in parallel with the connection point of the large chamber of the left lifting cylinder 3); the outlet port of the left second solenoid directional valve 4.2 is connected to the inlet port of the left first solenoid directional valve 4.1; the outlet port of the left first solenoid directional valve 4.1 is connected to the hydraulic return circuit.

[0054] The control terminal of the left electro-proportional relief valve 4.3 is electrically connected to the controller and receives the control electrical signal output by the controller.

[0055] When de-energized, both the left first solenoid directional valve 4.1 and the left second solenoid directional valve 4.2 are in the cut-off position, cutting off the connection between the left lifting cylinder 3 and the hydraulic return circuit; the left electro-proportional relief valve 4.3 is in the cut-off position when de-energized, cutting off the connection between the small chamber of the left lifting cylinder 3 and the hydraulic return circuit.

[0056] The right variable float valve assembly 7 includes: Right first solenoid directional valve 7.1: is a two-position two-way solenoid directional valve; Right second solenoid directional valve 7.2: a two-position, two-way solenoid directional valve; Right electro-proportional relief valve 7.3: This is a normally closed electro-proportional relief valve.

[0057] The large chamber oil port of the right lifting cylinder 6 is connected to the oil inlet of the right second solenoid directional valve 7.2; the oil outlet of the right second solenoid directional valve 7.2 is connected to the oil inlet of the right first solenoid directional valve 7.1; and the oil outlet of the right first solenoid directional valve 7.1 is connected to the hydraulic return oil circuit.

[0058] The small chamber port of the right lifting cylinder 6 is connected to the inlet port of the right electro-proportional relief valve 7.3; the outlet port of the right electro-proportional relief valve 7.3 is connected to the inlet port of the right second solenoid directional valve 7.2 (connected in parallel with the connection point of the large chamber of the right lifting cylinder 6); the outlet port of the right second solenoid directional valve 7.2 is connected to the inlet port of the right first solenoid directional valve 7.1; the outlet port of the right first solenoid directional valve 7.1 is connected to the hydraulic return circuit.

[0059] The control terminal of the right electro-proportional relief valve 7.3 is electrically connected to the controller and receives the control electrical signal output by the controller.

[0060] When the right first solenoid directional valve 7.1 and the right second solenoid directional valve 7.2 are both in the off position when de-energized, cutting off the connection between the right lifting cylinder 6 and the hydraulic return circuit; when the right electro-proportional relief valve 7.3 is in the off position when de-energized, cutting off the connection between the small chamber of the right lifting cylinder 6 and the hydraulic return circuit.

[0061] In some embodiments, combined with Figure 2 As shown, the present invention also includes a controller, which is electrically connected to the following components: The mode selection switch on the control panel includes non-floating mode, dual-cylinder floating mode, left single-cylinder floating mode, and right single-cylinder floating mode. Left float force adjustment knob; Right float force adjustment knob; Left first solenoid directional valve 4.1, left second solenoid directional valve 4.2, left electro-proportional relief valve 4.3; Right first solenoid directional valve 7.1, right second solenoid directional valve 7.2, right electro-proportional relief valve 7.3; The controller is configured to output control signals to the corresponding solenoid directional valve and electro-proportional relief valve based on the mode selection switch signal and the floating force adjustment knob signal, thereby achieving precise control over the floating state and floating force of the blade.

[0062] When the operator selects the no-float mode via the mode selection switch: The controller outputs a power-off signal to the left first solenoid directional valve 4.1, the left second solenoid directional valve 4.2, the right first solenoid directional valve 7.1, and the right second solenoid directional valve 7.2. Both the left first solenoid directional valve 4.1 and the left second solenoid directional valve 4.2 are in the cut-off position, cutting off the connection between the large and small chambers of the left lifting cylinder 3 and the hydraulic return circuit; Both the right first solenoid directional valve 7.1 and the right second solenoid directional valve 7.2 are in the cut-off position, cutting off the connection between the large and small chambers of the right lifting cylinder 6 and the hydraulic return circuit; The left lifting cylinder 3 and the right lifting cylinder 6 are locked by the left balance valve 2, the right balance valve 5, and the left and right variable floating valve groups. The blade is in a fixed locked state and cannot float up or down.

[0063] When the operator selects the dual-cylinder floating mode via the mode selection switch: The controller outputs an electrical signal to the left first solenoid directional valve 4.1, the left second solenoid directional valve 4.2, the right first solenoid directional valve 7.1, and the right second solenoid directional valve 7.2. Left lifting cylinder 3: Large cavity oil circuit: Left lifting cylinder 3 large cavity → Left second solenoid directional valve 4.2 (energized and connected) → Left first solenoid directional valve 4.1 (energized and connected) → Hydraulic return oil circuit, the large cavity and the return oil circuit are connected; Small cavity oil circuit: Left lifting cylinder 3 small cavity → left electro-proportional relief valve 4.3 → left second solenoid directional valve 4.2 (energized) → left first solenoid directional valve 4.1 (energized) → hydraulic return oil circuit, the small cavity is connected to the return oil circuit through the left electro-proportional relief valve 4.3; The left lifting cylinder 3 enters a floating state.

[0064] Right lifting cylinder 6: Large cavity oil circuit: Right lifting cylinder 6 large cavity → Right second solenoid directional valve 7.2 (energized and connected) → Right first solenoid directional valve 7.1 (energized and connected) → hydraulic return oil circuit, the large cavity and the return oil circuit are connected; Small cavity oil circuit: right lifting cylinder 6 small cavity → right electro-proportional relief valve 7.3 → right second solenoid directional valve 7.2 (energized) → right first solenoid directional valve 7.1 (energized) → hydraulic return oil circuit, the small cavity is connected to the return oil circuit through the right electro-proportional relief valve 7.3; Right lifting cylinder 6 enters floating state.

[0065] Both the left lifting cylinder 3 and the right lifting cylinder 6 are in a floating state, allowing the blade to move up and down with the undulations of the ground.

[0066] When the operator selects the left single-cylinder floating mode via the mode selection switch: The controller outputs an electrical signal to the first left solenoid directional valve 4.1 and the second left solenoid directional valve 4.2; The controller outputs a power-off signal to the right first solenoid directional valve 7.1 and the right second solenoid directional valve 7.2; Left lifting cylinder 3: Enters the floating state according to the left cylinder path in the above dual-cylinder floating mode; Right lifting cylinder 6: Because the right first solenoid directional valve 7.1 and the right second solenoid directional valve 7.2 are both de-energized and cut off, the large and small chambers of the right lifting cylinder 6 are cut off from the hydraulic return oil circuit and are in a locked state. Only the left blade can float with the ground, while the right blade remains stationary, making it suitable for special working conditions such as obstacle avoidance on one side.

[0067] When the operator selects the right single-cylinder floating mode via the mode selection switch: The controller outputs a power-off signal to the left first solenoid directional valve 4.1 and the left second solenoid directional valve 4.2; The controller outputs an electrical signal to the right first solenoid directional valve 7.1 and the right second solenoid directional valve 7.2; Left lifting cylinder 3: Because the left first solenoid directional valve 4.1 and the left second solenoid directional valve 4.2 are both de-energized and cut off, the large and small chambers of the left lifting cylinder 3 are cut off from the hydraulic return oil circuit and are in a locked state. Right lifting cylinder 6: Enters the floating state according to the right cylinder path in the above dual-cylinder floating mode; Only the right blade can float with the rise and fall of the ground, while the left blade remains stationary.

[0068] In this embodiment of the invention, under any floating mode (dual-cylinder floating, left single-cylinder floating, or right single-cylinder floating), the controller executes the following floating force adjustment steps in parallel: Left float force adjustment: Read the knob signal R_L of the left float force adjustment knob; Based on a preset mapping relationship (such as an inverse proportional relationship), the left knob signal R_L is converted into the corresponding left control current I_L; The output current I_L of the left-side proportional relief valve 4.3 is... The left electro-proportional relief valve 4.3 establishes a corresponding back pressure P_L based on the current I_L, and this back pressure acts on the small chamber of the left lifting cylinder 3. Back pressure P_L offsets part of the weight of the left blade, thereby adjusting the force exerted by the left blade on the ground: the higher the back pressure, the more weight is offset, and the smaller the force exerted by the blade on the ground; the lower the back pressure, the less weight is offset, and the greater the force exerted by the blade on the ground.

[0069] Right float force adjustment: Read the knob signal R_R of the right float force adjustment knob; Based on the preset mapping relationship, R_R is converted into the corresponding current value I_R; The right-hand proportional relief valve 7.3 outputs current I_R; The right electro-proportional relief valve 7.3 establishes a corresponding back pressure P_R based on the current I_R, and this back pressure acts on the small chamber of the right lifting cylinder 6. Back pressure P_R offsets part of the weight of the right blade, thereby adjusting the force exerted by the right blade on the ground.

[0070] Example of an inverse proportional relationship: The larger the knob signal (the greater the expected force of the blade on the ground), the smaller the control signal and the lower the back pressure; the smaller the knob signal (the smaller the expected force of the blade on the ground), the larger the control signal and the higher the back pressure.

[0071] Through the above adjustments, the force exerted by the shovel on the ground can be steplessly adjusted from zero (completely offsetting its own weight) to the maximum value (its own weight is completely applied to the ground).

[0072] This invention also provides a control method for a grader using the variable floating device described in the above embodiments, comprising the following steps: S1. Read the mode selection switch signal on the operation panel to determine the target working mode; If the target working mode is no floating mode, execute S2; if the target working mode is floating mode, execute S3. S2. Output a power failure signal to all solenoid directional valves to disconnect all lifting cylinders from the hydraulic return circuit, thus locking the blade. S3. Based on the selected floating mode, an energizing signal is output to the corresponding solenoid directional valve, connecting the large chamber of the corresponding lifting cylinder to the hydraulic return circuit, and the small chamber to the hydraulic return circuit via the electro-proportional relief valve, thus entering the floating state; In the floating state, the following parallel operations are performed: (1) Read the signal of the left floating force adjustment knob, and output the corresponding control electrical signal to the left electro-proportional overflow valve according to the signal, so that it provides stepless adjustable back pressure to the small chamber of the left lifting cylinder to offset part of the self-weight of the blade, thereby realizing stepless adjustment of the force of the blade on the ground; (2) Read the signal of the right floating force adjustment knob, and output the corresponding control electrical signal to the right electro-proportional overflow valve according to the signal, so that it provides stepless adjustable back pressure to the small chamber of the right lifting cylinder to offset part of the self-weight of the blade, thereby realizing stepless adjustment of the force of the blade on the ground.

[0073] In some embodiments, to ensure consistency in the adjustment of the left and right floating forces, the following steps are performed after initial use or system maintenance: Figure 3 The following are the initial calibration steps for the buoyancy force: a) Position the grader on a horizontal reference surface, raise the blade to mid-air, and level the blade to the preset height using the leveling device; b) Activate the left floating function (energize the left first solenoid directional valve and the left second solenoid directional valve), and set the input electrical signal of the left electro-proportional relief valve to the maximum value (at this time, the back pressure is the highest, the blade is fully supported and will not descend). c) Gradually decrease the input electrical signal of the left electro-proportional relief valve according to the preset step size (such as 0.1V or 10mA), while monitoring the position of the piston rod of the left lifting cylinder through the position sensor; d) When the piston rod of the left lifting cylinder begins to move downward, record the current electrical signal value as the left-side basic calibration value K_L; e) Turn off the left floating function, level the scraper again, then activate the right floating function, repeat steps b) to d), and record the right basic calibration value K_R; f) Store the basic calibration values ​​K_L and K_R on the left and right sides in the controller.

[0074] In actual operation, the controller performs compensation calculations based on the left floating force adjustment knob signal R_L and K_L, and outputs the final control electrical signal; the same applies to the right side. This calibration eliminates the differences between the left and right hydraulic systems and mechanical structures, ensuring the consistency of the left and right floating forces.

[0075] In some embodiments, to improve operational safety, the controller also performs the following intelligent protection steps: The controller is connected via CAN bus or hardwire to acquire the vehicle speed signal detected by the vehicle speed sensor in real time. When the detected vehicle speed exceeds a preset safety threshold (e.g., 15 km / h), the controller will automatically perform the following actions regardless of the current floating mode selection switch status: Output a power failure signal to the left first solenoid directional valve, the left second solenoid directional valve, the right first solenoid directional valve, and the right second solenoid directional valve; All solenoid directional valves are reset to the cut-off position, cutting off the connection between the left and right lifting cylinders and the hydraulic return circuit. The blade exits the floating state and enters the locked mode; At the same time, the controller sends an alarm signal to the instrument panel, indicating "Vehicle speed too high, floating function has automatically disengaged".

[0076] This protection feature prevents the blade from falling unexpectedly due to accidental activation of the float switch while traveling at high speed, thus avoiding safety accidents.

[0077] Those skilled in the art will clearly understand that the techniques in the embodiments of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium such as a USB flash drive, mobile hard drive, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, or other media capable of storing program code. It includes several instructions to cause a computer terminal (which may be a personal computer, server, or a second terminal, network terminal, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0078] In the embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0079] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0080] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0081] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A variable floating device for a grader, applied to a grader blade floating control system having a left lifting cylinder and a right lifting cylinder, wherein the large chambers of the left and right lifting cylinders are respectively connected to a main valve via a balance valve, characterized in that, The device includes: A left variable floating valve assembly is connected between the left lifting cylinder and the hydraulic return circuit; The right variable floating valve assembly is connected between the right lifting cylinder and the hydraulic return circuit; Each variable floating valve group includes: At least one solenoid directional valve is used to connect the large chamber of the corresponding lifting cylinder to the hydraulic return circuit when energized. An electro-proportional relief valve has its inlet connected to the small chamber of the corresponding lifting cylinder and its outlet connected to the hydraulic return circuit. The electro-proportional relief valve is used to provide steplessly adjustable back pressure to the small chamber of the corresponding lifting cylinder according to the received control electrical signal, so as to offset part of the blade's self-weight and thus adjust the force of the blade on the ground.

2. The variable floating device for a grader according to claim 1, characterized in that, It also includes a controller, which is electrically connected to the electro-proportional relief valve. The controller is configured to receive a floating force adjustment signal and output a control electrical signal to the electro-proportional relief valve according to the floating force adjustment signal.

3. The variable floating device for a grader according to claim 1, characterized in that, The electromagnetic reversing valve includes a first electromagnetic reversing valve and a second electromagnetic reversing valve. The large chamber of the lifting cylinder is connected to the hydraulic return circuit in sequence through the second electromagnetic reversing valve and the first electromagnetic reversing valve. The small chamber of the lifting cylinder is connected to the hydraulic return circuit in sequence through the electro-proportional relief valve, the second solenoid directional valve and the first solenoid directional valve. The electro-proportional relief valve and the first electromagnetic directional valve are connected in series on the oil line from the small cavity of the corresponding lifting cylinder to the hydraulic return oil line.

4. The variable floating device for a grader according to claim 1, characterized in that, The inlets of the left and right variable floating valve groups are connected in parallel to the hydraulic lines between the corresponding balance valves and the corresponding lifting cylinders, and their outlets are connected to the hydraulic return lines, forming independently installed modular valve groups.

5. The variable floating device for a grader according to claim 1, characterized in that, The solenoid directional valve is a two-position two-way solenoid directional valve, which disconnects the lifting cylinder from the hydraulic return circuit when the power is off. The electro-proportional relief valve is a normally closed electro-proportional relief valve, which cuts off the connection between the lifting cylinder small chamber and the hydraulic return circuit when the power is off.

6. A control method for a grader employing the variable floating device as described in any one of claims 3 to 5, characterized in that, Includes the following steps: Read the mode selection switch signal on the operation panel to determine the target working mode; If the target working mode is the non-floating mode, then output a power failure signal to all solenoid directional valves, cut off the connection between all lifting cylinders and hydraulic return circuit, and put the blade in the locked state. If the target operating mode is floating mode, then according to the selected specific floating mode, an electrical signal is output to the corresponding solenoid directional valve, so that the large chamber of the corresponding lifting cylinder is connected to the hydraulic return circuit, and the small chamber is connected to the hydraulic return circuit through the electro-proportional relief valve, thus entering the floating state; in the floating state, the following parallel operations are performed: Read the signal from the left floating force adjustment knob, and output the corresponding control signal to the left electro-proportional overflow valve according to the signal, so that it provides steplessly adjustable back pressure to the small chamber of the left lifting cylinder to offset part of the blade's own weight, thereby realizing stepless adjustment of the blade's force on the ground; The signal from the right floating force adjustment knob is read, and a corresponding control signal is output to the right electro-proportional overflow valve based on the signal, so that it provides steplessly adjustable back pressure to the small chamber of the right lifting cylinder to offset part of the blade's own weight, thereby realizing stepless adjustment of the blade's force on the ground.

7. The control method for the variable floating device of a grader according to claim 6, characterized in that, The floating modes include dual-cylinder floating mode and single-cylinder floating mode; Dual-cylinder floating mode control steps: The first and second solenoid directional valves in the left variable floating valve group output electrical signals, so that the large chamber of the left lifting cylinder is connected to the hydraulic return circuit through the second and first solenoid directional valves in sequence, and the small chamber of the left lifting cylinder is connected to the hydraulic return circuit through the electro-proportional relief valve, the second solenoid directional valve and the first solenoid directional valve in sequence. The first and second solenoid directional valves in the right-side variable floating valve group output electrical signals, so that the large chamber of the right lifting cylinder is connected to the hydraulic return circuit through the second and first solenoid directional valves in sequence, and the small chamber of the right lifting cylinder is connected to the hydraulic return circuit through the electro-proportional relief valve, the second solenoid directional valve and the first solenoid directional valve in sequence. Single-cylinder floating mode control steps: When the left single-cylinder floating is selected, the first solenoid directional valve and the second solenoid directional valve in the left variable floating valve group are output with an energized signal, and the first solenoid directional valve and the second solenoid directional valve in the right variable floating valve group are output with a de-energized signal. When the right single-cylinder floating mode is selected, the first and second solenoid directional valves in the right variable floating valve group are output with an energized signal, and the first and second solenoid directional valves in the left variable floating valve group are output with a de-energized signal.

8. The control method for the variable floating device of a grader according to claim 7, characterized in that, This includes the initial buoyancy force calibration procedure, which should be performed after first use or maintenance: a) Position the grader on a horizontal reference surface, raise the blade and level it to the preset height; b) Activate the variable floating valve group on one side and set the input electrical signal of the electro-proportional relief valve on that side to the maximum value; c) Reduce the input electrical signal of the electro-proportional relief valve on this side according to the set step size, while monitoring the position of the piston rod of the lifting cylinder on this side; d) When the piston rod begins to move downwards, record the current electrical signal value as the baseline calibration value for that side; e) Repeat steps b) to d) to calibrate the other side; f) Store the basic calibration values ​​of the left and right sides in the controller to compensate for the control of the electro-proportional relief valve in actual operation, and ensure the consistency of the left and right floating forces.

9. The control method for the variable floating device of a grader according to claim 7, characterized in that, It also includes intelligent protection steps: The controller acquires vehicle speed signals in real time. When the vehicle speed is detected to be higher than the preset safety threshold, the power supply to all solenoid directional valves is automatically cut off regardless of the floating mode selection switch status, causing the blade to exit the floating state and enter the locking mode.

10. The control method for the variable floating device of a grader according to claim 7, characterized in that, In the parallel execution steps under floating state, the left floating force adjustment knob signal, the right floating force adjustment knob signal, and the control electrical signal of the electro-proportional relief valve are inversely proportional: the larger the knob signal, the smaller the control electrical signal, the lower the back pressure, and the greater the force exerted by the blade on the ground; the smaller the knob signal, the larger the control electrical signal, the higher the back pressure, and the smaller the force exerted by the blade on the ground.

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