Inertia disk saw hydraulic system, control method and engineering machinery

Abstract

The invention relates to the technical field of inertial disk saws, in particular to an inertial disk saw hydraulic system, a control method and engineering machinery. After the disk saw is started, the controller firstly works in the constant-torque speed increasing mode to enable the variable displacement motor to rotate in an accelerated mode, the constant-torque speed increasing mode can provide the maximum torque requirement, and the real-time rotating speed of the variable displacement motor can be rapidly increased; and after the real-time rotating speed of the variable displacement motor reaches the critical rotating speed, the controller works in a constant-power speed increasing mode of keeping the maximum power, so that the real-time rotating speed of the variable displacement motor is further increased to the maximum rotating speed, the motor displacement of the disc is automatically adjusted by comparing the target torque and the actual torque in real time, speed increasing is stable, and the working efficiency is improved. And the real-time rotating speed of the variable displacement motor is kept at the critical rotating speed during continuous operation, so that re-acceleration within the interval waiting time is avoided, and the working efficiency is further improved.

Description

Technical Field

[0001] This invention relates to the field of inertial disc saw technology, specifically to an inertial disc saw hydraulic system, control method, and engineering machinery. Background Technology

[0002] Logging machinery is widely used. Circular saws are a type of inertia saw that relies on the cutting force generated by the inertia of the disc itself to cut down trees. Generally, a hydraulic motor is used to accelerate the disc to a certain ultra-high speed, and the edge of the disc is equipped with cutting teeth; when the motor oil circuit is disconnected, the disc continues to rotate under inertia, and then cuts the tree.

[0003] During operation, circular saws cannot automatically adjust the motor displacement of the disc according to working conditions. During work breaks, the disc speed decreases or even drops to zero, requiring it to be accelerated back to its maximum operating speed from a standstill, which consumes time and power. Traditional circular saws use variable displacement motors, whose displacement changes with pressure, and cannot automatically adjust the motor displacement of the disc according to working conditions, resulting in unstable speed increases. Furthermore, circular saws have intermittent waiting times, during which they need to be readjusted, affecting work efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an inertial circular saw hydraulic system, control method, and engineering machinery. The system first operates in a constant torque acceleration mode to accelerate the variable displacement motor to a critical speed. After the variable displacement motor reaches the critical speed, it operates in a constant power acceleration mode. During the constant power acceleration mode, the target torque and the real-time torque are compared in real time. The real-time displacement of the variable displacement motor is adjusted by controlling the valve core opening of the second proportional solenoid valve to maintain constant power and a stable acceleration process. During continuous operation, the real-time speed of the variable displacement motor is maintained at the critical speed, avoiding re-acceleration during intermittent waiting time, thereby improving work efficiency.

[0005] In a first aspect, the present invention provides an inertial circular saw hydraulic system, comprising a hydraulic pump, an oil tank, and a variable displacement motor for driving the circular saw, wherein the hydraulic pump comprises a main pump and a pilot pump, and includes: The hydraulic directional valve has its inlet connected to the main pump and its return port connected to the oil tank. The first working port and the second working port are respectively connected to the inlet and return ports of the variable displacement motor. The first proportional solenoid valve has its inlet connected to the pilot pump and its outlet connected to the left control terminal of the hydraulic directional valve. When the first proportional solenoid valve is energized, the pilot oil output by the pilot pump acts on the control terminal of the hydraulic directional valve. The inlet of the hydraulic directional valve is connected to the first working port, and the second working port is connected to the return port. The second proportional solenoid valve has its inlet connected to the pilot pump and in parallel with the inlet of the first proportional solenoid valve, and its outlet connected to the displacement control mechanism of the variable displacement motor. The real-time displacement of the variable displacement motor can be controlled by adjusting the valve core opening of the second proportional solenoid valve. A speed sensor is used to detect the real-time speed of the variable displacement motor; The first pressure sensor and the second pressure sensor are used to detect the real-time pressure at the oil inlet and oil outlet of the variable displacement motor, respectively. The controller is communicatively connected to the first proportional solenoid valve, the second proportional solenoid valve, the speed sensor, the first pressure sensor, and the second pressure sensor.

[0006] Optionally, the hydraulically controlled directional valve includes a left position and a right position; When the hydraulic control directional valve is in the left position, the oil inlet and the first working oil port are connected. When the hydraulic control directional valve is in the right position, both the first working port and the second working port are connected to the oil tank.

[0007] Optionally, the hydraulically controlled directional valve further includes: The third relief valve has its inlet connected to the first working port of the hydraulic directional valve, and its outlet connected to the second working port of the hydraulic directional valve.

[0008] Optionally, it also includes: The first relief valve and the second relief valve are connected to the oil outlets of the main pump and the pilot pump, respectively.

[0009] Optionally, it also includes: The throttle valve is located between the second proportional solenoid valve and the displacement control mechanism of the variable displacement motor.

[0010] In a second aspect, the present invention provides a control method for an inertial circular saw hydraulic system, comprising: Step S1: In response to receiving the power-on signal from the circular saw, the controller operates in constant torque speed-up mode to accelerate the rotation of the variable displacement motor. Step S2: In response to the speed sensor detecting that the real-time speed n of the variable displacement motor has reached the critical speed n c Upon receiving the initial acceleration completion signal, the controller operates in a constant power acceleration mode that maintains maximum power, wherein the critical speed n... c Based on the predetermined maximum power P max and maximum torque T max Sure; Step S3: In response to receiving the speed sensor detecting that the real-time speed n of the variable displacement motor has reached the maximum speed n maxWhen the operation preparation is complete, the controller sends a first opening signal to the second proportional solenoid valve, causing the real-time displacement V of the variable displacement motor to change. m Maintaining the first displacement V0, while the main pump outputs hydraulic oil to ensure that the real-time speed n of the variable displacement motor 5 under the first displacement V0 can be maintained at the maximum speed n. max ; Step S4: In response to receiving the felling start signal from the circular saw, acquire the real-time rotational speed n detected by the speed sensor; in response to receiving the real-time rotational speed n of the variable displacement motor detected by the speed sensor being less than the critical speed n... c The controller operates in constant torque speed-increasing mode as per the feedback speed increase signal in step S1, responding to the speed sensor detecting that the real-time speed n of the variable displacement motor has increased to the post-critical speed n. c After receiving the acceleration completion signal, the controller sends a second opening signal to the second proportional solenoid valve, causing the real-time displacement V of the variable displacement motor to change. m Maintaining the second displacement V1; simultaneously, the controller controls the main pump to output hydraulic oil so that the real-time speed n of the variable displacement motor under the first displacement V0 can be maintained at the critical speed n. c ; Step S5: In response to the received logging completion signal from the circular saw, the controller operates in the constant power acceleration mode of step S2, increasing the circular saw speed to n. max The circular saw is maintained by step S3. max .

[0011] Optionally, the constant torque increase mode operation in step S1 includes: The controller outputs current to the first proportional solenoid valve to activate it. Pilot oil from the pilot pump passes through the first proportional solenoid valve and acts on the control terminal of the hydraulic directional valve. The inlet of the hydraulic directional valve is connected to the first working port, and the second working port is connected to the return port. The controller sends a maximum opening signal to the second proportional solenoid valve. When the second proportional solenoid valve is at its maximum opening, the pilot oil output from the pilot pump acts on the displacement control mechanism of the variable displacement motor via the second proportional solenoid valve, and the variable displacement motor maintains its maximum displacement V. m-max The controller controls the main pump to output hydraulic oil to accelerate the rotation of the variable displacement motor.

[0012] Optionally, the operation process of the constant power increase mode in step S2 includes: The controller controls the main pump to output hydraulic oil to accelerate the rotation of the variable displacement motor. The controller adjusts the valve core opening of the second proportional solenoid valve in real time with the goal of maintaining maximum power. Optionally, the controller adjusts the valve spool opening of the second proportional solenoid valve in real time with the goal of maintaining maximum power, including: The target torque is calculated based on the preset maximum power and the real-time angular velocity of the variable displacement motor; The actual torque is calculated based on the real-time displacement of the variable displacement motor and the pressure difference between the inlet and outlet of the variable displacement motor. If the target torque is less than the actual torque, the controller sends a signal to the second proportional solenoid valve to reduce the opening until the target torque is greater than or equal to the actual torque. If the target torque is greater than the actual torque and the difference between the target torque and the actual torque is greater than a preset threshold, the controller sends an opening increase signal to the second proportional solenoid valve until the difference between the target torque and the actual torque is less than or equal to the preset threshold.

[0013] Thirdly, the present invention provides an engineering machine, characterized in that it includes the aforementioned inertial circular saw hydraulic system.

[0014] Compared with the prior art, the present invention has the following beneficial effects: In this invention, the controller after the circular saw initially operates in a constant torque acceleration mode to accelerate the rotation of the variable displacement motor. This constant torque acceleration mode provides the maximum torque required, rapidly increasing the real-time speed of the variable displacement motor. Once the real-time speed of the variable displacement motor reaches the critical speed, the controller switches to a constant power acceleration mode to maintain maximum power, further increasing the real-time speed of the variable displacement motor to the maximum speed. In the constant power acceleration mode, the controller adjusts the valve core opening of the second proportional solenoid valve in real time with the goal of maintaining maximum power. By controlling the valve core opening of the second proportional solenoid valve, the real-time displacement of the variable displacement motor can be adjusted to achieve active control of the motor displacement. By comparing the target torque and the actual torque in real time, the motor displacement of the circular saw is autonomously adjusted. During continuous operation, the real-time speed of the variable displacement motor is maintained at the critical speed, avoiding re-acceleration during intermittent waiting time, thereby improving work efficiency. Attached Figure Description

[0015] Figure 1 A hydraulic schematic diagram of an inertial circular saw hydraulic system provided in an embodiment of the present invention; Figure 2 A schematic diagram of the working parts of a circular saw used in an inertial circular saw hydraulic system provided in an embodiment of the present invention; Figure 3 This is a control block diagram of an inertial circular saw hydraulic system provided in an embodiment of the present invention.

[0016] Numbering on the map: 1. Hydraulic pump; 2. Oil tank; 3. Controller; 4. Hydraulic directional valve; 5. Variable displacement motor; 5-1. Speed ​​sensor; 5-2. First pressure sensor; 5-3. Second pressure sensor; 6. First proportional solenoid valve; 7. Second proportional solenoid valve; 8. First relief valve; 9. Second relief valve; 10. Throttle valve. Detailed Implementation

[0017] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0019] To make the purpose, technical solution and advantages of this invention patent clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0020] Combination Figure 1 and Figure 2 This embodiment provides an inertial circular saw hydraulic system, including a hydraulic pump 1, an oil tank 2, and a variable displacement motor 5 for driving the circular saw. The hydraulic pump 1 includes a main pump and a pilot pump, and the oil outlets of the main pump and the pilot pump are respectively connected to a first relief valve 8 and a second relief valve 9. The hydraulic system of the inertial circular saw also includes a hydraulically controlled directional valve 4, a first proportional solenoid valve 6, a second proportional solenoid valve 7, a speed sensor 5-1, a first pressure sensor 5-2, and a second pressure sensor 5-3.

[0021] The hydraulic directional valve 4 has its inlet connected to the main pump and its return port connected to the oil tank 2. The first working port and the second working port are respectively connected to the inlet and return port of the variable displacement motor 5. The hydraulic directional valve 4 has left and right positions. When the hydraulic directional valve 4 is in the left position, its inlet and the first working port are connected. When the hydraulic directional valve 4 is in the right position, both the first and second working ports are connected to the oil tank 2. The hydraulic directional valve 4 also includes a third relief valve. The inlet of the third relief valve is connected to the first working port of the hydraulic directional valve 4, and its outlet is connected to the second working port of the hydraulic directional valve 4.

[0022] The inlet of the first proportional solenoid valve 6 is connected to the pilot pump, and the outlet is connected to the left control terminal of the hydraulic directional valve 4. When the first proportional solenoid valve 6 is energized, the pilot oil output by the pilot pump acts on the control terminal of the hydraulic directional valve 4. The inlet of the hydraulic directional valve 4 is connected to the first working port, and the second working port is connected to the return port. The inlet of the second proportional solenoid valve 7 is connected to the pilot pump and is connected in parallel with the inlet of the first proportional solenoid valve 6. The outlet is connected to the displacement control mechanism of the variable displacement motor 5. The real-time displacement of the variable displacement motor 5 can be controlled by adjusting the valve core opening of the second proportional solenoid valve 7. A throttle valve 10 is provided between the second proportional solenoid valve 7 and the displacement control mechanism of the variable displacement motor 5.

[0023] The speed sensor 5-1 is used to detect the real-time speed n of the variable displacement motor; the first pressure sensor 5-2 and the second pressure sensor 5-3 are used to detect the real-time pressure at the oil inlet and oil outlet of the variable displacement motor 5, respectively; the controller 3 is communicatively connected to the first proportional solenoid valve 6, the second proportional solenoid valve 7, the speed sensor 5-1, the first pressure sensor 5-2 and the second pressure sensor 5-3.

[0024] Combination Figure 3 The following describes a control method for an inertial circular saw hydraulic system, the control method comprising: In order for the disc saw to quickly reach the set speed, during the operation, as the disc saw accelerates from a standstill to the predetermined maximum speed, the hydraulic system initially provides the maximum torque demand, resulting in a large acceleration that can quickly increase the real-time speed n of the variable displacement motor 5; when the real-time speed n of the variable displacement motor 5 reaches the critical speed n... c At this point, the hydraulic system enters the constant power increase phase, and controller 3 adjusts (reduces) the motor displacement in real time until the maximum speed is reached. The specific control process is as follows: Step S1: In response to receiving the power-on signal from the circular saw, the controller 3 operates in constant torque speed-up mode to accelerate the rotation of the variable displacement motor 5. When the real-time speed n of the variable displacement motor 5 is less than or equal to the critical speed n c At that time, the hydraulic system provides a constant maximum torque T max : T max =k1×Δp max ×V m-max =k1×p max ×V m-max ; Where: k1 is the first coefficient; Δp max p is the pressure difference acting on the inlet and outlet of the motor. max For the maximum hydraulic system pressure, Δp is approximately calculated. max =p max V m-max V represents the maximum displacement of the variable displacement motor 5; n represents the real-time speed of the variable displacement motor 5; V m The real-time displacement of the variable displacement motor 5; At the same time, controller 3 controls the main pump displacement V p =k2×n×V m / n p +Δv1; k2 is the second coefficient; Δv1 is the variable that breaks the steady state and accelerates the variable displacement motor 5, which is related to the rotational inertia and speed of the circular saw, and its specific value is determined based on an empirical model; n p This represents the engine speed and also the pump's input speed.

[0025] The constant torque acceleration mode operates as follows: the controller 3 outputs current to the first proportional solenoid valve 6, causing it to conduct; the pilot oil output by the pilot pump passes through the first proportional solenoid valve 6 and acts on the control terminal of the hydraulic directional valve 4; the inlet of the hydraulic directional valve 4 is connected to the first working port, and the second working port is connected to the return port; the controller 3 sends a maximum opening signal to the second proportional solenoid valve 7, causing it to be at its maximum opening; the pilot oil output by the pilot pump passes through the second proportional solenoid valve 7 and acts on the displacement control mechanism of the variable displacement motor 5; the variable displacement motor 5 maintains its maximum displacement V. m-max Controller 3 controls the main pump to output hydraulic oil to accelerate the rotation of variable displacement motor 5 until the real-time speed n of variable displacement motor 5 reaches the critical speed n. c .

[0026] S2: In response to the speed sensor 5-1 detecting that the real-time speed n of the variable displacement motor 5 has reached the critical speed n cUpon receiving the initial acceleration completion signal, the controller operates in a constant power acceleration mode that maintains maximum power, wherein the critical speed n... c Based on the predetermined maximum power P max and maximum torque T max Determined, n c =k3×P max / T max k3 is the third coefficient; controller 3 controls the main pump to output hydraulic oil to accelerate the rotation of the variable displacement motor 5, and controller 3 maintains the maximum power P. max The valve core opening of the second proportional solenoid valve 7 is adjusted in real time to achieve the target. First, based on the preset maximum power P... max The target torque T is calculated from the real-time angular velocity ω of the variable displacement motor 5. 目标 T 目标 =k4×P maxt / ω, the angular velocity of the disk ω=2πn; k4 is the fourth coefficient; the actual torque T is calculated based on the real-time displacement of the variable displacement motor 5 and the pressure difference between the oil inlet and outlet of the variable displacement motor 5. 实际 The inlet pressure p of the variable displacement motor 5 is detected by the first pressure sensor 5-2 and the second pressure sensor 5-3. in and oil outlet p out Thus, Δp = p in -p out Therefore, we can conclude that: T 实际 =k5×V m ×Δp; k5 is the fifth coefficient; Controller 3 compares T 实际 With T 目标 The difference is used to control the valve core opening of the second proportional solenoid valve 7 to adjust the motor displacement V in real time. m This makes T 实际 Approaching T 目标 This ensures the system maximizes motor speed with maximum power. If the target torque T... 目标 Less than the actual torque T 实际 Controller 3 sends a signal to the second proportional solenoid valve 7 to decrease the opening degree until T 目标 Greater than or equal to T 实际 If the target torque T 目标 Greater than the actual torque T 实际 And the target torque T 目标 and actual torque T 实际 When the difference is greater than a preset threshold, controller 3 sends an opening increase signal to the second proportional solenoid valve 7 until T... 目标 and T 实际 The difference is less than or equal to a preset threshold. Simultaneously, controller 3 controls the main pump displacement V. p =k6×n×Vm / n p +Δv2; Δv2 is the variable that breaks the steady state and increases the speed of the variable displacement motor 5. It is related to the rotational inertia and speed of the circular saw. The specific value is determined based on the empirical model.

[0027] The specific adjustment process for motor displacement is as follows: S2-1: When T 目标 -T 实际 When the value is less than 0, it indicates that the system is operating at overpower, posing a risk. At this time, the controller 3 sends a signal to the second proportional solenoid valve 7 to reduce its opening. The second proportional solenoid valve 7 is energized, and the signal to reduce its opening moves the valve core upward, thus reducing the displacement V of the control motor. m The pilot pressure causes the variable piston of the variable displacement motor 5 to move upward. The displacement control mechanism controlled by the piston reduces the swashplate angle of the variable displacement motor 5, thus increasing the real-time displacement V of the variable displacement motor 5. m Decrease; at this time, as the real-time displacement V of the variable displacement motor 5 decreases... m Decrease, T 实际 Consequently, it decreases; simultaneously, controller 3 compares T. 目标 With T 实际 The difference, until 0 ≤ T 目标 -T 实际 ≤ΔT; S2-2: When T 目标 -T 实际 When the torque is greater than ΔT, it is determined that the actual torque of the variable displacement motor 5 needs to be further increased. At this time, the controller 3 sends an opening increase signal to the second proportional solenoid valve 7. The second proportional solenoid valve 7 is energized, and the opening increase signal controls the valve core of the second proportional solenoid valve 7 to move down, increasing the valve core opening and increasing the real-time displacement V of the variable displacement motor 5. m The pilot pressure causes the variable piston to move downwards, and the piston-controlled displacement control mechanism increases the swashplate angle of the variable displacement motor 5, thereby increasing the real-time displacement V of the variable displacement motor 5. m Increase; at this time, as the real-time displacement V of the variable displacement motor 5 increases... m Increase, T 实际 As a result, it increases; simultaneously, the controller compares T. 目标 With T 实际 The difference, until 0 ≤ T 目标 -T 实际 ≤ΔT; ΔT is related to the moment of inertia of the disk, which is confirmed based on test experience and numerical models.

[0028] Step S3: In response to receiving a signal from the speed sensor 5-1 that the real-time speed n of the variable displacement motor 5 has reached its maximum speed n max Upon receiving the feedback signal indicating that the work preparation is complete, the controller 3 sends a first opening signal to the second proportional solenoid valve 7, causing the real-time displacement V of the variable displacement motor 5 to change.m Maintaining the first displacement V0, while the main pump outputs hydraulic oil to ensure that the real-time speed n of the variable displacement motor 5 under the first displacement V0 can be maintained at the maximum speed n. max ; When the real-time speed of the variable displacement motor 5 is n=n max When the circular saw reaches its maximum speed, meeting operational requirements, the controller 3 sends a ready signal to the operator via communication equipment, indicating that logging operations can commence. At this time, the controller 3 sends a first opening signal to the second proportional solenoid valve 7, causing the real-time displacement V of the variable displacement motor 5 to... m The first displacement is V0; at the first displacement V0, the output torque of the variable displacement motor 5 can just offset the external resistance of the disc, so that the real-time speed n of the variable displacement motor 5 is maintained at the maximum speed n. max The first displacement, V0, was obtained through experimental testing and is related to the system and the disk's moment of inertia.

[0029] Among them, controller 3 controls the main pump displacement Vp=k2×n max ×V0 / n p To maintain the motor speed. Simultaneously, the controller 3 acquires the real-time speed of the variable displacement motor 5 detected by the speed sensor 5-1, when n max If -n > Δn, then follow steps S1 and S2 to restore and maintain the real-time speed n of the variable displacement motor 5 to n. max The value of Δn is determined by the working conditions and the working capacity of the circular saw, and needs to be learned through on-the-job training.

[0030] Step S4: In response to receiving the felling start signal from the circular saw (which can be determined by the torque sensor), acquire the real-time rotational speed n detected by the speed sensor 5-1; in response to receiving the real-time rotational speed n of the variable displacement motor 5 detected by the speed sensor 5-1 being less than the critical speed n... c The controller 3 operates in the constant torque speed-increasing mode of step S1, responding to the speed sensor 5-1 detecting that the real-time speed n of the variable displacement motor 5 has increased to the critical speed n. c Upon receiving the acceleration completion signal, the controller 3 sends a second opening signal to the second proportional solenoid valve 7, thereby increasing the real-time displacement V of the variable displacement motor 5. m Maintaining the second displacement V1; under the second displacement V1, the output torque of the variable displacement motor 5 can counteract the external resistance of the disc, while the controller 3 controls the main pump to output hydraulic oil so that the real-time speed n of the variable displacement motor 5 under the first displacement V0 can be maintained at the critical speed n. c The main pump displacement is V p =k2×n c ×V1 / n p .

[0031] Step S5: In response to the received logging completion signal from the circular saw, controller 3 operates in the constant power acceleration mode of step S2, increasing the speed of the circular saw to n. max The circular saw is maintained by step S3. max .

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydraulic system for an inertial circular saw, comprising a hydraulic pump, an oil tank, and a variable displacement motor for driving the circular saw, wherein the hydraulic pump comprises a main pump and a pilot pump, characterized in that, include: The hydraulic directional valve has its inlet connected to the main pump and its return port connected to the oil tank. The first working port and the second working port are respectively connected to the inlet and return ports of the variable displacement motor. The first proportional solenoid valve has its inlet connected to the pilot pump and its outlet connected to the left control terminal of the hydraulic directional valve. When the first proportional solenoid valve is energized, the pilot oil output by the pilot pump acts on the control terminal of the hydraulic directional valve. The inlet of the hydraulic directional valve is connected to the first working port, and the second working port is connected to the return port. The second proportional solenoid valve has its inlet connected to the pilot pump and in parallel with the inlet of the first proportional solenoid valve, and its outlet connected to the displacement control mechanism of the variable displacement motor. The real-time displacement of the variable displacement motor can be controlled by adjusting the valve core opening of the second proportional solenoid valve. A speed sensor is used to detect the real-time speed of the variable displacement motor; The first pressure sensor and the second pressure sensor are used to detect the real-time pressure at the oil inlet and oil outlet of the variable displacement motor, respectively. The controller is communicatively connected to the first proportional solenoid valve, the second proportional solenoid valve, the speed sensor, the first pressure sensor, and the second pressure sensor.

2. The hydraulic system for an inertial circular saw according to claim 1, characterized in that, The hydraulically controlled directional valve includes a left position and a right position; When the hydraulic control directional valve is in the left position, the oil inlet and the first working oil port are connected. When the hydraulic control directional valve is in the right position, both the first working port and the second working port are connected to the oil tank.

3. The hydraulic system for an inertial circular saw according to claim 1, characterized in that, The hydraulically controlled directional valve also includes: The third relief valve has its inlet connected to the first working port of the hydraulic directional valve, and its outlet connected to the second working port of the hydraulic directional valve.

4. The hydraulic system for an inertial circular saw according to claim 1, characterized in that, Also includes: The first relief valve and the second relief valve are connected to the oil outlets of the main pump and the pilot pump, respectively.

5. The hydraulic system for an inertial circular saw according to claim 1, characterized in that, Also includes: The throttle valve is located between the second proportional solenoid valve and the displacement control mechanism of the variable displacement motor.

6. A control method for a hydraulic system of an inertial circular saw, characterized in that, include: Step S1: In response to receiving the power-on signal from the circular saw, the controller operates in constant torque speed-up mode to accelerate the rotation of the variable displacement motor. Step S2: In response to the speed sensor detecting that the real-time speed n of the variable displacement motor has reached the critical speed n c Upon receiving the initial acceleration completion signal, the controller operates in a constant power acceleration mode that maintains maximum power, wherein the critical speed n... c Based on the predetermined maximum power P max and maximum torque T max Sure; Step S3: In response to receiving the speed sensor detecting that the real-time speed n of the variable displacement motor has reached the maximum speed n max When the operation preparation is complete, the controller sends a first opening signal to the second proportional solenoid valve, causing the real-time displacement V of the variable displacement motor to change. m Maintaining the first displacement V0, while the main pump outputs hydraulic oil to ensure that the real-time speed n of the variable displacement motor 5 under the first displacement V0 can be maintained at the maximum speed n. max ; Step S4: In response to receiving the felling start signal from the circular saw, acquire the real-time rotational speed n detected by the speed sensor; in response to receiving the real-time rotational speed n of the variable displacement motor detected by the speed sensor being less than the critical speed n... c The controller operates in constant torque speed-increasing mode as per the feedback speed increase signal in step S1, responding to the speed sensor detecting that the real-time speed n of the variable displacement motor has increased to the critical speed n. c Upon receiving the acceleration completion signal, the controller sends a second opening signal to the second proportional solenoid valve, causing the real-time displacement V of the variable displacement motor to change. m Maintaining the second displacement V1; simultaneously, the controller controls the main pump to output hydraulic oil so that the real-time speed n of the variable displacement motor under the first displacement V0 can be maintained at the critical speed n. c ; Step S5: In response to the received logging completion signal from the circular saw, the controller operates in the constant power acceleration mode of step S2, increasing the circular saw speed to n. max The circular saw is maintained by step S3. max .

7. The control method for an inertial circular saw hydraulic system according to claim 6, characterized in that, The constant torque increase mode operation in step S1 includes: The controller outputs current to the first proportional solenoid valve to activate it. Pilot oil from the pilot pump passes through the first proportional solenoid valve and acts on the control terminal of the hydraulic directional valve. The inlet of the hydraulic directional valve is connected to the first working port, and the second working port is connected to the return port. The controller sends a maximum opening signal to the second proportional solenoid valve. When the second proportional solenoid valve is at its maximum opening, the pilot oil output from the pilot pump acts on the displacement control mechanism of the variable displacement motor via the second proportional solenoid valve, and the variable displacement motor maintains its maximum displacement V. m-max The controller controls the main pump to output hydraulic oil to accelerate the rotation of the variable displacement motor.

8. The control method for an inertial circular saw hydraulic system according to claim 6, characterized in that, The working process of the constant power increase mode in step S2 includes: The controller controls the main pump to output hydraulic oil to accelerate the rotation of the variable displacement motor. The controller adjusts the valve core opening of the second proportional solenoid valve in real time with the goal of maintaining maximum power.

9. The control method for an inertial circular saw hydraulic system according to claim 8, characterized in that, The controller adjusts the valve spool opening of the second proportional solenoid valve in real time with the goal of maintaining maximum power, including: The target torque is calculated based on the preset maximum power and the real-time angular velocity of the variable displacement motor; The actual torque is calculated based on the real-time displacement of the variable displacement motor and the pressure difference between the inlet and outlet of the variable displacement motor. If the target torque is less than the actual torque, the controller sends a signal to the second proportional solenoid valve to reduce the opening until the target torque is greater than or equal to the actual torque. If the target torque is greater than the actual torque and the difference between the target torque and the actual torque is greater than a preset threshold, the controller sends an opening increase signal to the second proportional solenoid valve until the difference between the target torque and the actual torque is less than or equal to the preset threshold.

10. An engineering machinery, characterized in that, The hydraulic system for inertial circular saws as described in any one of claims 1-5.

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