A profile hobbing mower and active and passive damping method and hob design method

Abstract

The application provides a profiled hob mower and a method for active and passive vibration reduction and a hob design method, three hob mower cutters are staggered arranged at the rear end of the mower, the hob is controlled to realize profiled ground by an electric push rod and an electric push rod slider mechanism, a magneto-rheological damper is arranged on the electric push rod and the electric push rod slider mechanism to realize active vibration reduction control, the posture of the spray rod is collected by an inclination sensor arranged on the hob, three ultrasonic distance measuring modules at the front end measure the distance to the ground, signals are sent to a control unit, the posture of the hob is accurately controlled by the control unit, rubber damping pads are arranged at the connection positions of the left and right hobs and the electric push rod slider mechanism and the hob and the electric push rod to realize passive vibration reduction. Through profiled adjustment and multi-modal vibration reduction technology, the application solves the problems of uneven cutting height and excessive body vibration under complex terrain, and through active vibration reduction, the stability of the hob is improved, energy is saved, and the application is suitable for efficient operation of hilly orchards and ridges.

Description

Technical Field

[0001] This invention relates to the field of orchard machinery technology, and in particular to a contour-following rotary mower, an active and passive vibration reduction method, and a rotary mower design method. Background Technology

[0002] Traditional spiral blade designs cause grass clippings to scatter along the spiral direction, making them difficult to collect and requiring secondary cleaning, thus increasing operational complexity. Especially in dense lawns, uneven accumulation of waste grass can negatively impact the lawn's aesthetics.

[0003] Existing lawnmowers are prone to uneven cutting depths in complex terrains (such as slopes and tall grass) due to unstable power transmission, and may even experience power interruptions due to the machine shoveling soil. In addition, the lack of a contour-following adjustment mechanism results in inconsistent stubble heights and difficulty in adapting to uneven ground.

[0004] Therefore, it is an urgent problem to solve the difficulty in ensuring a smooth stubble and stable operation of mowing equipment when mowing on undulating terrain. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a contour-following rotary mower, an active and passive vibration reduction method, and a rotary mower design method. Through contour-following adjustment and active and passive vibration reduction technologies, multi-modal composite vibration reduction is achieved at the blade end. Furthermore, through the coordinated control of ultrasonic ranging and an electric actuator slider mechanism, the blade is kept in constant contact with the ground contour, enabling precise control of the stubble height, improving mowing quality and equipment stability. This invention also relates to a rotary mower design method, which enables the design of the rotary mower required by this invention.

[0006] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0007] A contour-following rotary mower includes a frame and a rotary mower actuator. The rotary mower actuator is located at the rear of the frame. The actuator includes three rotary mowers: a first rotary mower, a second rotary mower, and a third rotary mower. The first rotary mower is positioned in the middle, while the second and third rotary mowers are positioned on either side of the first rotary mower. Each of the three rotary mowers is supported by one end of a rotary mower support frame. The other end of the support frame is rotatably connected to the frame via a pivot. The middle section of the support frame is connected to the output end of an electric actuator, which is mounted on the frame. The extension and retraction of the electric actuator causes the rotary mower support frame to swing relative to the frame, thereby adjusting the height of the rotary mowers relative to the ground. The rotary mowers are driven by a rotary mower drive motor. Both the second and third rotary mowers are equipped with an electric actuator slider mechanism. The output end of this mechanism is connected to the second and third rotary mowers via a pivot and a slide rail C. The operation of this mechanism causes the second and third rotary mowers to swing up and down relative to the ground, thus achieving contour-following motion.

[0008] In the above scheme, the electric push rod slider mechanism includes a drive rod, a push rod, and mutually perpendicular slides A and B. The drive rod is slidably engaged with slide A, and the push rod is slidably engaged with slide B. The drive rod and the push rod are connected by a connecting rod, which is hinged to both the drive rod and the push rod. The hobbing motion drive motor drives the drive rod to slide along slide A via an intermediate rod, thereby driving the push rod to slide along slide B, which in turn drives the connecting rod to swing up and down. The output end of the push rod is connected to slide C via a rotating shaft.

[0009] In the above scheme, the slide C is opened on the connecting rod, the connecting rod is a hollow tube, and the two connecting rods are respectively installed on the input shafts of the second cutter and the third cutter. A hole is opened on the outer wall of one side of the connecting rod, and the hole is rotatably connected to the extension shaft of the cutter support frame.

[0010] The above scheme also includes a control unit and a data acquisition unit; the data acquisition unit includes three ultrasonic ranging modules installed at the front end of the frame and an inclination sensor set at the input shaft of the cutter; the data acquisition unit is used to collect ground height information and cutter attitude data in real time; the control unit calculates the target cutter height deviation by fusing the data from the ultrasonic ranging modules and the inclination sensor through a control algorithm, and sends displacement commands to the electric actuator and the electric actuator slider mechanism through the CAN bus.

[0011] In the above scheme, the control unit uses a filtering algorithm to fuse ultrasonic ranging data and tilt sensor data, and generates vibration reduction commands through a PID control algorithm.

[0012] The above scheme also includes an active and passive vibration reduction system, which includes a first magnetorheological damper and a second magnetorheological damper respectively installed on the electric push rod and the electric push rod slider mechanism, and rubber damping pads installed at the connection between the cutter and the connecting rod and on the electric push rod slider mechanism.

[0013] In the above scheme, the damping coefficients of the first magnetorheological damper and the second magnetorheological damper are infinitely variable within the range of 10 to 500 Ns / m by adjusting the current. The rubber damping pad is made of natural rubber with a hardness of 70±5 Shore A, which is used to attenuate vibrations in the 100 to 500 Hz frequency band.

[0014] The active-passive composite vibration reduction method for a contour-following rotary mower includes the following steps: real-time acquisition of ground height data in front via an ultrasonic ranging module; acquisition of real-time attitude data of the rotary mower via an tilt sensor; fusion of ranging and attitude data by a control unit to calculate the target blade height deviation and damping adjustment parameters; sending displacement commands to the electric actuator and its slider mechanism to adjust the rotary mower height and tilt angle; dynamic adjustment of the current in the first and second magnetorheological dampers based on the vibration frequency to achieve active vibration reduction; and passive attenuation of high-frequency vibrations via rubber damping pads and spring washers to form an active-passive composite vibration reduction system.

[0015] A method for designing a rotary cutter for use in a contour rotary lawnmower.

[0016] Step 1: The hobbing cutter adopts a centrally symmetrical helical design, with the first cutting edge angle being α1 and the second cutting edge angle being α2, where α1 = α2; the cutting edge angle is designed according to the formula F = (σ·t·sinα) / (μ+sinα), and the first cutting edge angle is taken as 11.5°~30°;

[0017] Step 2: Combining the electric actuator stroke L and the hob radius R, the range of tilt angle variation is calculated using geometric relationships: θ=arcsin(L / R)=arcsin(80 / R), so R=80 / sin(θ), and the reasonable design range of θ is 5°~15°; the hob cutting edge tilt angle is 90-θ, that is, 75°~85°;

[0018] Step 3: The radius of the hob is 80.31~82.83mm.

[0019] In the above scheme, the first cutting edge angle is 20°, the rolling radius is 82mm, and the blade's penetration angle relative to the grass stem, β, is calculated using the formula β = tan -1 (Vx / Vy), where Vx is the horizontal cutting speed of the blade (m / s), calculated using the formula Vx=ωR, where ω is the angular velocity of the blade (rad / s), and Vy is the vertical speed of the blade relative to the grass blade (m / s), calculated using the formula Vy=Vx×tan(90-θ). Through calculation, it can be found that when the rotary mower maintains a rotary speed of 3000 rpm, it can maintain a blade-to-grass stem engagement angle of 13.77°.

[0020] Beneficial effects:

[0021] Applicable Scenarios and Advantages: This invention is suitable for orchard terrain scenarios. Compared to traditional lawnmowers, it features: Height Adaptability: Achieves precise contour following within a ±80mm range, with stubble height fluctuations meeting the needs of agricultural and forestry operations; High-Efficiency Vibration Reduction: Active + passive composite vibration reduction significantly reduces additional excitation caused by environmental factors, effectively improving equipment lifespan and operational accuracy; Energy Saving and Environmental Protection: By actively controlling the damping changes of the magnetorheological damper to suppress high-frequency amplitude, compared to the high-frequency suppression of amplitude by a transmission damping system, overall energy consumption is significantly reduced while still meeting stable operation requirements. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a three-dimensional structure according to an embodiment of the present invention;

[0023] Figure 2 This is a top view of the shell removed according to an embodiment of the present invention;

[0024] Figure 3 This is a front view of the housing removed according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the hobbing tool posture contouring structure according to an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of the hob structure according to an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of a hob following the ground profile according to an embodiment of the present invention.

[0028] Figure label:

[0029] 1-Frame; 2-Battery box; 3-Wheel; 4-Roller electric push rod; 5-Roller support frame; 6-Roller attitude drive motor; 7-Roller electric push rod slider mechanism; 8-Roller; 9-Tilt sensor; 10-Oil tank; 11-Spring washer; 12-Infrared ranging module; 13-Extend shaft; 14-Roller drive motor; 15-First magnetorheological damper; 16-Rubber washer; 17-Control unit; 18-Drive unit; 19-Push rod; 20-Active rod; 21-Second magnetorheological damper; 22-First cutting edge angle; 23-Second cutting edge angle; 24-Roller radius; 25-Roller blade tilt angle; 26-Blade penetration angle relative to grass stem; Vx-Horizontal cutting speed of blade (m / s), Vy-Vertical speed of blade relative to grass blade (m / s); 27-Slide A; 28-Connecting rod; 29-Slide B; 30-Slide C. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are 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" and "second" 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" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., 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 can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] Combined with appendix Figure 1 As shown, the present invention provides a contoured rotary mower, which includes a frame 1, a battery box 2, an oil tank 10, a rotary mower actuator, a control unit 17, a data acquisition unit, and a drive unit 18.

[0034] The hobbing actuator includes three hobbing cutters 8, which are arranged laterally and staggered at the rear end of the frame 1. The left and right hobbing cutters are located at the rear, and the middle hobbing cutter is located at the front. The overlap area between the three hobbing cutters is 20-50mm. Each hobbing cutter 8 is connected to the frame 1 through an independent electric push rod 4. The electric push rod 4 integrates a first magnetorheological damper 15. The current is adjusted by the control unit 17 to change the damping characteristics in real time, so as to achieve active vibration reduction for the high-frequency vibration of the three hobbing cutters and the hobbing cutter support frame 5 in the rotation direction relative to the frame.

[0035] The roller cutter follows the contours of the ground. Rollers 8-A and 8-C on the left and right sides are hinged to the electric push rod slider mechanism 7 via connecting rod 40, and driven by the roller cutter attitude drive motor 6. The electric push rod slider mechanism 7 adopts a double-rail structure, consisting of mutually perpendicular slide rails A27 and B29. The active rod 20 slides with slide rail A27, and the push rod 19 slides with slide rail B29. The active rod 20 and push rod 19 are connected by a connecting rod 28, which is hinged to both. The push rod 19 has a stroke of ±80mm, allowing the roller cutter to swing up and down with the terrain to achieve contour following. The electric push rod slider mechanism 7 has a second magnetorheological damper 21 at its end. The damping characteristics are changed in real time by adjusting the current through the control unit 17, actively reducing the up-and-down swing of the roller cutter relative to the roller cutter support frame 5 caused by external forces and machine vibrations during operation.

[0036] The data acquisition unit includes three ultrasonic ranging modules 12 installed at the front end of the frame 1, and an inclination sensor 9 set at the cutter shaft, for real-time acquisition of ground height information and cutter attitude data;

[0037] The control unit 17 calculates the target tool height deviation by integrating the data from the ultrasonic ranging module 12 and the tilt sensor 9 through the control algorithm, and sends displacement and damping commands to the electric push rod 4 and the electric push rod slider mechanism 7 via the CAN bus, so that the deviation of the hob 8 tilt angle from the ground normal does not exceed 5°.

[0038] The active-passive composite vibration reduction system comprises an active vibration reduction component consisting of a magnetorheological damper 15 integrated into an independent electric actuator on each hob and a second magnetorheological damper 21 located at the end of the electric actuator slider mechanism 7. Its damping coefficient is infinitely variable within the range of 10-500 Ns / m via current adjustment. Rubber damping pads 16, made of natural rubber with a hardness of 70±5 Shore A, are installed at the connection between the hob 8 and the connecting rod, and at the electric actuator slider mechanism, to attenuate vibrations in the 100-500 Hz frequency range. The magnetorheological damper has a damping coefficient c = 10-500 Ns / m and needs to suppress the hob vibration amplitude to ≤2 mm. According to the vibration equation: Assume the system's natural frequency f n =50Hz, damping ratio ζ=c / 2√(mk), it can be calculated that when c=500Ns / m, ζ≈0.7, which can effectively suppress resonance.

[0039] Hobbing cutter combination attachment Figure 5 and attached Figure 6As shown, the hobbing cutter adopts a centrally symmetrical helical design, so the first cutting edge angle 22 and the second cutting edge angle 23 are equal, and α1=α2. The cutting edge angle design is based on the formula F=(σ·t·sinα) / (μ+sinα), where the coefficient of friction μ between cork / hardwood and stainless steel can be obtained from the table as (0.2-0.5), the grass stem thickness t is assumed to be 2mm, and the grass stem shear strength σ is assumed to be 50MPa. After calculation, the cutting edge angle can be obtained as 11.5°~30°. Considering the actual operation requirements and processing costs, this invention decides to design the hobbing cutter cutting edge angle to be 20°. The blade tilt angle 25° of the rotary cutter needs to meet the contouring requirements under terrain undulations of ±80mm. Combining the push rod stroke and the rotary cutter radius 24(R), the tilt angle variation range can be calculated geometrically: θ=arcsin(L / R)=arcsin(80 / R), where R=80 / sin(θ). The reasonable design range for the tilt angle θ of traditional disc mowers is 5°~15°. This invention relates to an ideal actual tilt angle of 90-θ (75°~85°), therefore, the ideal rotary cutter radius is 80.31-82.83mm. Considering practical considerations, this invention designs the rotary cutter radius to be 82mm. The blade's relative blade penetration angle to the grass stem is 26(β), where β=tan -1 (Vx / Vy), where Vx is the horizontal cutting speed of the blade (m / s), Vx=ωR, ω is the angular velocity of the blade (rad / s), and Vy is the vertical speed of the blade relative to the grass blade (m / s), Vy=Vx×tan(90-θ). It can be calculated that when the rotary mower of the present invention maintains a rotary speed of 3000rpm, it can maintain a blade relative to the grass stem with an infiltration angle of 13.77°.

[0040] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0041] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A contour-following rotary mower, characterized in that, It includes a frame (1), an active and passive vibration damping system, and a hobbing cutter actuator; the hobbing cutter actuator is located on the rear side below the frame (1); The roller cutter actuator includes three roller cutters (8), namely the first roller cutter, the second roller cutter, and the third roller cutter. The first roller cutter is placed in the middle, and the second and third roller cutters are placed on both sides of the first roller cutter. The three roller cutters are supported by one end of the roller cutter support frame (5). The other end of the roller cutter support frame (5) is rotatably connected to the frame (1) through a rotating shaft. The middle section of the roller cutter support frame (5) is connected to the output end of the electric push rod (4). The electric push rod (4) is mounted on the frame (1). The extension and retraction of the electric push rod (4) can drive the roller cutter support frame (5) to swing relative to the frame (1), thereby adjusting the height of the roller cutter (8) relative to the ground. The roller cutter (8) is driven by the roller cutter drive motor (14). Electric push rod slider mechanism (7) is provided on the roller support frame (5) where the second and third rollers are located. The output end of the electric push rod slider mechanism (7) is connected to the slide rail C (30) through the rotating shaft of the second and third rollers. The operation of the electric push rod slider mechanism (7) can drive the second and third rollers to swing up and down relative to the ground to achieve ground contouring. The active and passive vibration reduction system includes a first magnetorheological damper (15) and a second magnetorheological damper (21) respectively installed on the electric push rod (4) and the electric push rod slider mechanism (7), and rubber damping pads (16) installed at the connection between the roller cutter (8) and the connecting rod and on the electric push rod slider mechanism (7). It also includes a control unit (17) and a data acquisition unit; the data acquisition unit includes three ultrasonic ranging modules (12) installed at the front end of the frame (1) and an inclination sensor (9) set at the input shaft of the cutter; the data acquisition unit is used to collect ground height information and cutter attitude data in real time; the control unit (17) calculates the target cutter height deviation by fusing the data of the ultrasonic ranging modules (12) and the inclination sensor (9) through the control algorithm, and sends displacement commands to the electric push rod (4) and the electric push rod slider mechanism (7) through the CAN bus; The ultrasonic ranging module (12) collects ground height data in real time; the tilt sensor (9) obtains the real-time attitude data of the hob (8); the control unit (17) integrates the ranging and attitude data to calculate the target tool height deviation and damping adjustment parameters; the control unit sends displacement commands to the electric push rod (4) and the electric push rod slider mechanism (7) to adjust the hob height and tilt angle; the control unit dynamically adjusts the current of the first magnetorheological damper (15) and the second magnetorheological damper (21) according to the vibration frequency to achieve active vibration reduction; the control unit passively attenuates high-frequency vibration through the rubber damping pad (16) and the spring washer (11) to form active and passive composite vibration reduction.

2. The contour-following rotary mower according to claim 1, characterized in that, The electric push rod slider mechanism (7) includes an active rod (20), a push rod (19), and mutually perpendicular slides A (27) and B (29). The active rod (20) is slidably engaged with slide A (27), and the push rod (19) is slidably engaged with slide B (29). The active rod (20) and the push rod (19) are connected by a connecting rod (28), which is hinged to the active rod (20) and the push rod (19) respectively. The hob attitude drive motor (6) drives the active rod (20) to slide along slide A (27) through the intermediate rod, thereby driving the push rod (19) to slide along slide B (29) and thus driving the connecting rod (28) to swing up and down. The output end of the push rod (19) is connected to slide C (30) through a rotating shaft.

3. The contour-following rotary mower according to claim 1, characterized in that, The slide rail C (30) is opened on the connecting rod, which is a hollow tube. The two connecting rods are respectively installed on the input shafts of the second and third cutters. A hole is opened on the outer wall of one side of the connecting rod, and the hole is rotatably connected to the extension shaft (13) of the cutter support frame (5).

4. The contour-following rotary mower according to claim 1, characterized in that, The control unit (17) uses a filtering algorithm to fuse ultrasonic ranging data and tilt sensor data, and generates vibration reduction commands through a PID control algorithm.

5. The contour-following rotary mower according to claim 1, characterized in that, The damping coefficients of the first magnetorheological damper (15) and the second magnetorheological damper (21) can be infinitely variable within 10~500 Ns / m by adjusting the current. The rubber damping pad (16) is made of natural rubber with a hardness of 70±5 Shore A, which is used to attenuate vibrations in the 100~500 Hz frequency band.

6. A hobbing cutter design method, characterized in that, The rotary cutter is used in any of the contour rotary cutter lawnmowers described in claims 1-5. Step 1: The hobbing cutter adopts a centrally symmetrical spiral design, with the first cutting edge angle (22) being α1 and the second cutting edge angle (23) being α2, α1=α2; the cutting edge angle design is based on the formula F=(σ⋅t⋅sinα) / (μ+sinα), and the first cutting edge angle (22) is 11.5°~30°; Step 2: Combining the electric push rod stroke L and the hob radius R, the range of the tilt angle variation is calculated through geometric relationship: θ=arcsin(L / R)=arcsin(80 / R), so R=80 / sin(θ), the reasonable design range of θ is 5°~15°; the hob blade tilt angle (25) is 90-θ, that is, 75°~85°; Step 3: The radius of the hobbing cutter (24) is 80.31~82.83mm.

7. The hobbing cutter design method according to claim 6, characterized in that, The first cutting edge angle (22) is 20°, the rolling radius (24) is 82mm, and the blade's relative cutting angle β (26) is calculated using the formula β=tan -1 (Vx / Vy), where Vx is the horizontal cutting speed of the blade (m / s), and according to the formula Vx=ωR, ω is the angular velocity of the blade (rad / s), and Vy is the vertical speed of the blade relative to the grass blade (m / s), and the formula Vy=Vx×tan(90-θ), it can be calculated that when the rotary mower maintains a rotary speed of 3000rpm, it can maintain a blade-to-grass stem infiltration angle of 13.77°.

Images