Driving structure of crawler belt of stretcher crawler

Abstract

The invention provides a driving structure of a crawler belt of a stretcher crawler, and belongs to the technical field of the stretcher crawler, the driving structure of the crawler belt of the stretcher crawler is provided with a dual-driving system, and a crawler belt assembly surrounds two driving wheels and a supporting wheel to form a complete transmission path. Crawler tension changes can be detected in real time, and the rotating speed of the second driving motor can be automatically adjusted. When the front-section resistance of the track is increased, the tension detection device senses the change, and the mechanical speed regulator reduces the rotating speed of the second driving wheel through the centrifugal block and the transmission gear set to form a rotating speed difference to increase the front-section tension of the track so as to provide larger traction force. The whole system follows the constraint relation that delta n = n1-n2 = k * delta T + C, it is ensured that the rotating speed difference linearly corresponds to the tension change, and accurate dynamic adjustment of the crawler tension is achieved through coordinated operation of the double driving wheels.

Description

Technical Field

[0001] The present invention belongs to the technical field of stretcher tracked vehicles, and more particularly, relates to a driving structure of a track of a stretcher tracked vehicle. Background Art

[0002] As a special medical rescue equipment, stretcher tracked vehicles are widely used in field rescue, mountain transportation, and medical first aid scenarios in complex terrains. Traditional tracked drive systems usually adopt a structural form of a single drive wheel cooperating with passive support wheels. A single motor drives the driving wheel to drive the track to run around, and the vehicle moves forward relying on the friction between the track and the ground. This traditional structure has good operating effects on flat ground and can meet the basic transportation needs in standard environments such as urban roads and hospital corridors. However, the traditional single-drive wheel system has significant technical defects. When the vehicle travels on rough mountainous, sandy, or slippery terrains, the load and resistance distribution on each section of the track are extremely uneven. The front section of the track may bear a large climbing resistance, while the resistance borne by the rear section of the track is relatively small. Since the entire track system can only maintain a fixed tension state and cannot be dynamically adjusted according to the actual working conditions, when the tension of the front section of the track is insufficient, slipping occurs, and when the tension of the rear section of the track is too large, unnecessary transmission losses and wear are generated. Traditional technologies are difficult to solve the core technical problem that the traction force is insufficient and the driving stability is poor due to the inability to dynamically adjust the track tension in real time during the driving process of tracked vehicles on complex terrains. Although existing electronically controlled tension adjustment systems can provide certain adjustment functions, their response speed is slow, and electronic component failures are likely to occur in harsh environments, unable to meet the reliability and real-time requirements of the system. Summary of the Invention

[0003] In view of this, the present invention provides a driving structure of a track of a stretcher tracked vehicle, which can solve the technical problems in the prior art that the traction force is insufficient and the driving stability is poor due to the inability to dynamically adjust the track tension in real time during the driving process of tracked vehicles on complex terrains.

[0004] The present invention is implemented as follows:

[0005] The present invention provides a driving structure for the crawler of a stretcher crawler vehicle, which includes a frame body and a crawler assembly. The frame body is made of high-strength aluminum alloy material and is in a rectangular frame structure. Circular mounting holes are provided at the four corners of the frame body. The crawler assembly is arranged around the outer periphery of the frame body. It further includes: a first driving wheel, located on the right side of the front end of the frame body, the first driving wheel is rotatably connected to the front mounting hole of the frame body through a bearing, and the tooth grooves of the first driving wheel are engaged with the inner rack of the crawler assembly to provide the main driving force for the forward movement of the crawler assembly; a second driving wheel, located on the right side of the rear end of the frame body, the second driving wheel is rotatably connected to the rear mounting hole of the frame body through a bearing, and the tooth grooves of the second driving wheel are engaged with the inner rack of the crawler assembly to provide the auxiliary driving force and tension adjustment function for the crawler assembly; a first supporting wheel and a second supporting wheel, respectively located on the left side of the front end and the rear end of the frame body, and arranged opposite to the first driving wheel and the second driving wheel; a first driving motor and a second driving motor, respectively driving the first driving wheel and the second driving wheel to rotate; a tension adjustment mechanism, which realizes the automatic adjustment of the tension of the crawler assembly by adjusting the rotation speed of the second driving motor, and realizes the precise dynamic adjustment of the crawler tension by establishing a linear relationship between the rotational speed difference and the tension difference through double driving wheel differential control. <{

[0006] Among them, the first driving wheel is made of high-strength steel and is in a circular disc structure. Uniformly distributed rectangular tooth grooves are provided on the outer periphery of the first driving wheel, and a circular shaft hole is provided at the center of the first driving wheel. The rectangular tooth grooves are used for precise meshing transmission with the inner rack of the crawler assembly.

[0007] Among them, the second driving wheel is made of the same high-strength steel as the first driving wheel and is in a circular disc structure. Uniformly distributed rectangular tooth grooves are provided on the outer periphery of the second driving wheel, and a circular shaft hole is provided at the center of the second driving wheel. When there is a difference in the rotation speed between the second driving wheel and the first driving wheel, the tension state of the crawler assembly changes accordingly.

[0008] Among them, the first supporting wheel is made of high-strength aluminum alloy material and is in a circular disc structure. The outer peripheral surface of the first supporting wheel is smooth without tooth grooves, and the outer peripheral surface of the first supporting wheel is in smooth contact with the inner side of the crawler assembly, which is used to support the front part of the crawler assembly and guide the crawler assembly to move along a predetermined path.

[0009] Among them, the second supporting wheel is made of the same high-strength aluminum alloy material as the first supporting wheel and is in a circular disc structure. The outer peripheral surface of the second supporting wheel is smooth without tooth grooves, and the outer peripheral surface of the second supporting wheel is in smooth contact with the inner side of the crawler assembly, which is used to support the rear part of the crawler assembly and maintain an appropriate tension state of the crawler assembly.

[0010] Among them, the crawler assembly is made by compounding a high-strength rubber material and steel cord, and is in a continuous annular belt structure. A rack structure matching the tooth grooves of the first driving wheel and the second driving wheel is provided on the inner side of the crawler assembly. An anti-slip pattern is provided on the outer side of the crawler assembly. The crawler assembly is arranged around the first driving wheel, the second driving wheel, the first supporting wheel and the second supporting wheel.

[0011] Among them, the first driving motor is fixedly installed inside the right front end of the vehicle frame main body. The first driving motor adopts a DC brushless motor. The output shaft of the first driving motor is connected to the shaft hole of the first driving wheel through a first transmission connecting shaft. The first driving motor drives the first driving wheel to rotate through the first transmission connecting shaft. The rotation speed of the first driving motor directly determines the rotation speed of the first driving wheel and the main movement speed of the crawler assembly.

[0012] Among them, the second driving motor is fixedly installed inside the right rear end of the vehicle frame main body. The second driving motor adopts a DC brushless motor with the same specification as the first driving motor. The output shaft of the second driving motor is connected to the shaft hole of the second driving wheel through a second transmission connecting shaft. The difference between the rotation speed of the second driving motor and the rotation speed of the first driving motor is used to adjust the tension state of the crawler assembly.

[0013] Among them, the tension adjusting mechanism includes a tension detecting device and a rotation speed adjusting device. The tension detecting device is arranged above the crawler assembly between the first supporting wheel and the second supporting wheel. The tension detecting device includes a pressure sensing rod and an elastic reset element. One end of the pressure sensing rod contacts the outer surface of the crawler assembly, and the other end is connected to the elastic reset element. When the tension of the crawler assembly increases, the moving distance of the pressure sensing rod downward increases, and the compression amount of the elastic reset element increases correspondingly.

[0014] Among them, the rotation speed adjusting device includes a mechanical speed governor and a transmission gear set. The mechanical speed governor works based on the centrifugal speed regulation principle. There are two symmetrically distributed centrifugal blocks inside the mechanical speed governor. The centrifugal blocks are connected to the central shaft of the mechanical speed governor through hinge shafts. When the rotation speed of the mechanical speed governor changes, the centrifugal force of the centrifugal blocks changes accordingly. The position change of the centrifugal blocks drives the adjusting rod to move, and the movement of the adjusting rod changes the transmission ratio of the transmission gear set.

[0015] Among them, it is characterized in that the transmission gear set includes a driving gear and a driven gear. When the tension state of the crawler assembly changes, the mechanical speed governor adjusts the rotation speed of the second driving motor through the transmission gear set to realize the automatic adjustment function of the tension of the crawler assembly. When the compression amount of the elastic reset element exceeds the preset value, the rotation speed adjusting device reduces the rotation speed of the second driving motor to make it lower than the rotation speed of the first driving motor, thereby reducing the tension of the crawler assembly.

[0016] When the first driving wheel and the second driving wheel perform differential motion, the rotational speed difference between the two driving wheels is controlled within a specified range. The tension adjustment response of the crawler assembly has a linear relationship with the rotational speed difference. The constraint relationship between the rotational speed of the first driving wheel and the rotational speed of the second driving wheel is that the rotational speed difference between the two driving wheels is equal to the rotational speed-tension coupling coefficient multiplied by the tension difference between the front and rear sections of the crawler assembly plus the system compensation constant.

[0017] Among them, when the first driving wheel rotates clockwise and its rotational speed is higher than that of the second driving wheel, the tension of the front section of the crawler assembly increases. The installation position of the second driving wheel is accurately aligned with the reference line on the right side of the rear end of the frame body. The parallelism deviation and the distance deviation between the axes of the two driving wheels are controlled within a specified range. When the mechanical speed governor responds to the tension change and performs the automatic adjustment function, the radial displacement of the centrifugal block is proportional to the square of the rotational speed of the speed governor.

[0018] Among them, the meshing depth constraint of the transmission gear set requires that the addendum circle and the dedendum circle of the driving gear and the driven gear maintain a standard meshing state. When the transmission ratio changes, the meshing point position of the gear always remains on the theoretical meshing line of the gear pair. The tooth surface contact stress distribution is uniform and no local stress concentration phenomenon occurs. The inner rack structure of the crawler assembly maintains a standard meshing depth with the rectangular tooth grooves of the first driving wheel and the second driving wheel.

[0019] Among them, when the rotational speeds of the first driving wheel and the second driving wheel are the same, the crawler assembly maintains a uniform tension distribution state. When the rotational speed of the first driving wheel is higher than that of the second driving wheel, the tension of the front section of the crawler assembly increases, and the tension of the rear section decreases accordingly. When the rotational speed of the second driving wheel is higher than that of the first driving wheel, the tension of the rear section of the crawler assembly increases, and the tension of the front section decreases accordingly.

[0020] Among them, by adjusting the rotational speed difference between the two driving wheels, the overall tension state and the local tension distribution of the crawler assembly change accordingly. The differential control of the double driving wheels realizes the precise adjustment of the crawler tension, making the crawler always maintain the best tension state. The response speed of the mechanical speed governor is fast and it does not depend on the electronic control system, improving the reliability and environmental adaptability of the system.

[0021] Compared with the prior art, the beneficial effects of the driving structure of the crawler of a stretcher crawler vehicle provided by the present invention are:

[0022] The present invention adopts an innovative solution that combines dual-drive wheel differential control technology with a mechanical tension adjustment mechanism, and realizes precise dynamic adjustment of the crawler tension through the coordinated operation of the first drive wheel and the second drive wheel. This technical solution can automatically adjust the rotational speed difference between the two drive wheels according to the actual load conditions of the front and rear sections of the crawler, thereby changing the tension distribution state of different sections of the crawler. The present invention effectively solves the technical defect that the crawler tension of the traditional single-drive wheel system remains fixed. When the vehicle encounters a complex terrain with an increased resistance ahead, the tension detection device can sense the change in the crawler tension in real time, and the mechanical speed governor immediately responds and adjusts the rotational speed of the second drive motor, making the rotational speed of the second drive wheel lower than that of the first drive wheel, automatically increasing the tension of the front section of the crawler to provide greater traction force. On the contrary, when the resistance ahead decreases, the system automatically reduces the tension of the front section of the crawler to avoid unnecessary energy loss. The entire adjustment process is completely based on mechanical principles, with a fast response speed and no dependence on the electronic control system, ensuring reliability in various harsh environments. By establishing a linear constraint relationship between the rotational speed difference and the tension change, precise control of the crawler tension is achieved, enabling the crawler vehicle to maintain the best traction performance and driving stability under any terrain conditions, and solving the core technical problems of insufficient traction force and poor driving stability caused by the inability to adjust the crawler tension in real time and dynamically during the driving process of the crawler vehicle on complex terrains. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a side view of the drive structure of the crawler of a stretcher crawler vehicle;

[0024] Figure 2 is a front cross-sectional view of the drive structure of the crawler of a stretcher crawler vehicle;

[0025] Figure 3 is a schematic structural diagram of the speed adjustment device of the drive structure of the crawler of a stretcher crawler vehicle;

[0026] In the drawings, the list of components represented by each reference numeral is as follows:

[0027] 10. Frame body; 11. First drive wheel; 12. Second drive wheel; 13. Bearing; 14. Tooth groove; 15. First support wheel; 16. Second support wheel; 19. Shaft hole; 20. Crawler assembly; 40. Tension detection device; 50. Speed adjustment device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

[0029] As Figures 1 - 3As shown, it is a flowchart of the drive structure of the crawler of a stretcher crawler vehicle provided by the present invention. The method includes the following steps:

[0030] A drive structure of the crawler of a stretcher crawler vehicle includes a frame main body 10 and a crawler assembly 20; the frame main body is made of high-strength aluminum alloy material and is in a rectangular frame structure. The length of the frame main body is 1100 - 1300 mm, the width is 750 - 850 mm, and the height is 280 - 320 mm. Circular mounting holes with a diameter of 18 - 22 mm are provided at the four corners of the frame main body for installing various drive components; the crawler assembly is arranged around the outer periphery of the frame main body; it is characterized in that it further includes:

[0031] A first drive wheel 11, located at the front end of the frame main body. The first drive wheel is made of high-strength steel and is in a circular disc structure. The diameter of the first drive wheel is 250 - 270 mm, and the thickness is 35 - 45 mm. 26 - 30 evenly distributed rectangular tooth grooves 14 are provided on the outer periphery of the first drive wheel. The depth of each rectangular tooth groove is 7 - 9 mm, and the width is 10 - 14 mm. A circular shaft hole 19 with a diameter of 23 - 27 mm is provided at the center of the first drive wheel. The first drive wheel is rotationally connected to the front mounting hole of the frame main body through a bearing 13. The tooth grooves of the first drive wheel are engaged with the inner rack of the crawler assembly to provide the main driving force for the forward movement of the crawler assembly;

[0032] A second drive wheel 12, located at the rear end of the frame main body. The second drive wheel is made of the same high-strength steel as the first drive wheel and is in a circular disc structure. The diameter of the second drive wheel is 230 - 250 mm, and the thickness is 35 - 45 mm. 22 - 26 evenly distributed rectangular tooth grooves are provided on the outer periphery of the second drive wheel. The depth of each rectangular tooth groove is 7 - 9 mm, and the width is 10 - 14 mm. A circular shaft hole with a diameter of 23 - 27 mm is provided at the center of the second drive wheel. The second drive wheel is rotationally connected to the rear mounting hole of the frame main body through a bearing. The tooth grooves of the second drive wheel are engaged with the inner rack of the crawler assembly to provide the auxiliary driving force and tension adjustment function of the crawler assembly. When there is a difference in the rotational speed between the second drive wheel and the first drive wheel, the tension state of the crawler assembly changes accordingly;

[0033] The first support wheel 15 is located on the left side of the front end of the vehicle frame main body, opposite to the first drive wheel. The first support wheel is made of high-strength aluminum alloy material and has a circular disc structure. The diameter of the first support wheel is 180 - 220 mm, and the thickness is 25 - 35 mm. The outer peripheral surface of the first support wheel is smooth without tooth grooves. A circular shaft hole is provided at the center of the first support wheel, and the shaft hole diameter is 18 - 22 mm. The first support wheel is rotationally connected to the left installation hole at the front end of the vehicle frame main body through a bearing. The outer peripheral surface of the first support wheel is in smooth contact with the inner side of the crawler assembly, and is used to support the front part of the crawler assembly and guide the crawler assembly to move along a predetermined path;

[0034] The second support wheel 16 is located on the left side of the rear end of the vehicle frame main body, opposite to the second drive wheel. The second support wheel is made of the same high-strength aluminum alloy material as the first support wheel and has a circular disc structure. The diameter of the second support wheel is 180 - 220 mm, and the thickness is 25 - 35 mm. The outer peripheral surface of the second support wheel is smooth without tooth grooves. A circular shaft hole is provided at the center of the second support wheel, and the shaft hole diameter is 18 - 22 mm. The second support wheel is rotationally connected to the left installation hole at the rear end of the vehicle frame main body through a bearing. The outer peripheral surface of the second support wheel is in smooth contact with the inner side of the crawler assembly, and is used to support the rear part of the crawler assembly and maintain the appropriate tension state of the crawler assembly;

[0035] The crawler assembly 20 is made by compounding high-strength rubber material and steel cord, and has a continuous annular belt structure. The total length of the crawler assembly is 3000 - 3400 mm, the width is 140 - 160 mm, and the thickness is 20 - 30 mm. A rack structure matching the tooth grooves of the first drive wheel and the second drive wheel is provided on the inner side of the crawler assembly. The tooth pitch of the rack is 32 - 38 mm, and the tooth height is 5 - 7 mm. Anti-slip patterns are provided on the outer side of the crawler assembly, and the pattern depth is 3 - 5 mm. The crawler assembly is arranged around the first drive wheel, the second drive wheel, the first support wheel and the second support wheel. The crawler assembly moves along an annular path under the drive of the first drive wheel and the second drive wheel. The tension state of the crawler assembly is directly affected by the rotational speed difference between the first drive wheel and the second drive wheel;

[0036] The first driving motor is fixedly installed inside the front end of the frame body. The first driving motor is a DC brushless motor with a rated power of 1200 - 1800W and a rated speed of 1600 - 2000r / min. The output shaft of the first driving motor is connected to the shaft hole of the first driving wheel through the first transmission connecting shaft. The first transmission connecting shaft is made of alloy steel material, has a cylindrical structure, a diameter of 23 - 27mm, and a length of 100 - 140mm. Key grooves are respectively provided at both ends of the first transmission connecting shaft, with a key groove depth of 4 - 6mm and a width of 6 - 10mm. The first driving motor drives the first driving wheel to rotate through the first transmission connecting shaft. The rotation speed of the first driving motor directly determines the rotation speed of the first driving wheel and the main movement speed of the crawler assembly;

[0037] The second driving motor is fixedly installed inside the rear end of the frame body. The second driving motor is a DC brushless motor with the same specifications as the first driving motor, with a rated power of 1200 - 1800W and a rated speed of 1600 - 2000r / min. The output shaft of the second driving motor is connected to the shaft hole of the second driving wheel through the second transmission connecting shaft. The second transmission connecting shaft is made of the same alloy steel material as the first transmission connecting shaft, has a cylindrical structure, a diameter of 23 - 27mm, and a length of 100 - 140mm. Key grooves are respectively provided at both ends of the second transmission connecting shaft, with a key groove depth of 4 - 6mm and a width of 6 - 10mm. The second driving motor drives the second driving wheel to rotate through the second transmission connecting shaft. The difference between the rotation speed of the second driving motor and the rotation speed of the first driving motor is used to adjust the tension state of the crawler assembly;

[0038] The tension adjustment mechanism includes a tension detection device 40 and a rotation speed adjustment device 50. The tension detection device is arranged above the crawler assembly between the first support wheel and the second support wheel. The tension detection device includes a pressure sensing rod and an elastic reset element. The pressure sensing rod is made of stainless steel material, has a slender rod-like structure, a length of 160 - 200mm, and a diameter of 6 - 10mm. One end of the pressure sensing rod contacts the outer surface of the crawler assembly, and the other end is connected to the elastic reset element. The elastic reset element is made of a stainless steel spring, with a free length of the spring of 50 - 70mm and a wire diameter of 1.5 - 2.5mm. When the tension of the crawler assembly increases, the downward movement distance of the pressure sensing rod increases, and the compression amount of the elastic reset element increases accordingly. The rotation speed adjustment device adjusts the rotation speed of the second driving motor according to the compression amount of the elastic reset element. When the compression amount of the elastic reset element exceeds the preset value of 18 - 22mm, the rotation speed adjustment device reduces the rotation speed of the second driving motor to be lower than that of the first driving motor, thereby reducing the tension of the crawler assembly;

[0039] The speed regulating device includes a mechanical governor and a transmission gear set. The mechanical governor works based on the centrifugal speed regulation principle. The main body of the mechanical governor is made of cast iron and has a cylindrical structure with a diameter of 70 - 90 mm and a height of 50 - 70 mm. Inside the mechanical governor, there are two symmetrically distributed centrifugal blocks made of copper alloy. The mass of each centrifugal block is 120 - 180 g. The centrifugal blocks are connected to the central axis of the mechanical governor through hinge shafts. When the speed of the mechanical governor changes, the centrifugal force of the centrifugal blocks changes accordingly, and the position change of the centrifugal blocks drives the regulating rod to move. The movement of the regulating rod changes the transmission ratio of the transmission gear set. The transmission gear set includes a driving gear and a driven gear. The number of teeth of the driving gear is 18 - 22, and the number of teeth of the driven gear is 22 - 26. When the tension state of the crawler assembly changes, the mechanical governor adjusts the speed of the second driving motor through the transmission gear set to achieve the automatic adjustment function of the crawler assembly tension;

[0040] When the first driving wheel and the second driving wheel perform differential motion, the speed difference between the two driving wheels must be controlled within a specified range, and the tension adjustment response of the crawler assembly must be linearly related to the speed difference. The specific constraint relationship between the speed of the first driving wheel and the speed of the second driving wheel is expressed as follows: Δn = n1 - n2 = k·ΔT + C, where Δn is the speed difference between the two driving wheels with the unit of r / min, n1 is the speed of the first driving wheel, n2 is the speed of the second driving wheel, ΔT is the tension difference between the front and rear sections of the crawler assembly with the unit of N, k is the speed-tension coupling coefficient with the numerical range of 8 - 12, and C is the system compensation constant with the value range of 15 - 25, which is used to compensate for the mechanical transmission loss and frictional resistance of the system;

[0041] When the first driving wheel rotates clockwise and its speed is higher than that of the second driving wheel, the increase amplitude of the tension in the front section of the crawler assembly must be controlled within a preset threshold range, and the ratio of the tension increase rate to the speed difference must be maintained within the range of 0.8 - 1.2. At this time, the installation position of the second driving wheel must be accurately aligned with the reference line on the right side of the rear end of the vehicle frame main body. The parallelism deviation between the axes of the two driving wheels shall not exceed 0.5 mm, and the distance deviation between the axes shall not exceed 0.1% of the design length of the crawler assembly. When the mechanical governor responds to the tension change and performs the automatic adjustment function, the radial displacement of the centrifugal block is proportional to the square of the governor speed. The adjustment force generated by the movement of the centrifugal block must be accurately transmitted to the transmission gear set through the regulating rod. The movement stroke range of the regulating rod is limited between 5 - 15 mm. When exceeding this range, the system will automatically lock to prevent over-adjustment;

[0042] The meshing depth constraint of the transmission gear set requires that the addendum circles and dedendum circles of the driving gear and the driven gear maintain a standard meshing state. The proportion of the meshing depth in the tooth height must be controlled within the range of 60% to 80%. The center distance deviation of the gear pair shall not exceed 0.2 mm. When the transmission ratio changes, the meshing point position of the gears must always be kept on the theoretical meshing line of the gear pair. The tooth surface contact stress distribution must be uniform and no local stress concentration phenomenon shall occur. The meshing depth between the inner rack structure of the crawler assembly and the rectangular tooth grooves of the first driving wheel is 5 - 7 mm, and the meshing depth between the inner rack structure of the crawler assembly and the rectangular tooth grooves of the second driving wheel is also 5 - 7 mm;

[0043] When the rotational speeds of the first driving wheel and the second driving wheel are the same, the crawler assembly maintains a uniform tension distribution state. When the rotational speed of the first driving wheel is higher than that of the second driving wheel, the tension in the front section of the crawler assembly increases, and the tension in the rear section decreases accordingly. When the rotational speed of the second driving wheel is higher than that of the first driving wheel, the tension in the rear section of the crawler assembly increases, and the tension in the front section decreases accordingly. By adjusting the rotational speed difference between the two driving wheels, the overall tension state and local tension distribution of the crawler assembly change accordingly. The traditional crawler drive system usually adopts a structure with a single driving wheel and a passive supporting wheel, which cannot achieve dynamic adjustment of the crawler tension, resulting in the crawler being prone to slipping or derailing under complex terrains. This constraint system realizes precise adjustment of the crawler tension through differential control of the two driving wheels, enabling the crawler to always maintain the best tension state, effectively improving the traction force and driving stability. Compared with the traditional electronic control adjustment method, the mechanical speed governor has a faster response speed, completing the tension adjustment within 0.1 - 0.3 s and not relying on the electronic control system, improving the reliability and environmental adaptability of the system. The precise control of the gear meshing depth avoids the common problems of gear wear and reduced transmission efficiency in the traditional system. The transmission efficiency reaches more than 92%, which is 5% - 8% higher than that of the conventional gear transmission. The strict constraints on the axis parallelism and center distance ensure the accuracy of power transmission, eliminating the vibration and noise caused by installation errors. The operating noise is controlled below 65 dB, which is 10 - 15 dB lower than that of the traditional crawler vehicle. The coordinated action of the overall constraint system enables the stretcher crawler vehicle to maintain good driving performance under various terrain conditions, with the load capacity increased by more than 20% and the service life extended by more than 30%, thus achieving the best driving performance and stability of the stretcher crawler vehicle under different terrain conditions.

[0044] The following describes the specific implementation manners of the above steps in detail. The present invention realizes precise control of the crawler tension through a mechanical tension adjustment mechanism. The entire device consists of five main parts: a frame body, a crawler assembly, a drive system, a support system, and a tension adjustment mechanism.

[0045] The main frame body is made of high-strength aluminum alloy material, specifically 6061-T6 aluminum alloy, and its tensile strength reaches over 310 MPa. The main frame body is in a rectangular frame structure, with the outer dimensions being 1100 - 1300 mm in length, 750 - 850 mm in width, and 280 - 320 mm in height. The frame is connected by welding technology, and the weld strength is not lower than 85% of the strength of the base material. Circular mounting holes are provided at all four corners of the main frame body, with the hole diameter being 18 - 22 mm, and the position accuracy requirement of the holes reaching ±0.1 mm, which are used to install various drive components. The inner surface of the mounting holes undergoes precision machining, and the surface roughness Ra value does not exceed 1.6 μm to ensure the accuracy requirements for bearing installation.

[0046] The first driving wheel is located on the right side at the front end of the main frame body and is made of 40Cr alloy steel material. After quenching and tempering treatment, its hardness reaches HRC28 - 32. The first driving wheel is in a circular disc structure, with a diameter of 250 - 270 mm and a thickness of 35 - 45 mm. There are 26 - 30 evenly distributed rectangular tooth grooves on the outer periphery of the disc. The depth of each rectangular tooth groove is 7 - 9 mm, the width is 10 - 14 mm, and the spacing between the tooth grooves is 30 - 35 mm. The machining accuracy requirement of the tooth grooves reaches IT7 level, and the surface roughness Ra value of the tooth grooves does not exceed 3.2 μm. A circular shaft hole is provided at the center of the first driving wheel, with the shaft hole diameter being 23 - 27 mm, and the shaft hole tolerance fit is H7 / k6. The first driving wheel is rotationally connected to the front mounting hole of the main frame body through a deep groove ball bearing, and the bearing model is 6205-2RZ, with a load-bearing capacity of 5600 N. The tooth grooves of the first driving wheel mesh with the inner rack of the crawler assembly, and the meshing depth is 5 - 7 mm, and the meshing area accounts for 60% - 80% of the total area of the tooth grooves.

[0047] The second driving wheel is located on the right side at the rear end of the main frame body and is made of the same 40Cr alloy steel material as the first driving wheel, and the heat treatment process is exactly the same. The second driving wheel is in a circular disc structure, with a diameter of 230 - 250 mm, 20 mm smaller than the diameter of the first driving wheel, and a thickness of 35 - 45 mm. There are 22 - 26 evenly distributed rectangular tooth grooves on the outer periphery of the second driving wheel. The depth of each rectangular tooth groove is 7 - 9 mm, the width is 10 - 14 mm, and the tooth groove spacing is 28 - 32 mm. A circular shaft hole is provided at the center of the second driving wheel, with the shaft hole diameter being 23 - 27 mm, and the machining accuracy of the shaft hole is the same as that of the first driving wheel. The second driving wheel is rotationally connected to the rear mounting hole of the main frame body through a deep groove ball bearing of the same specification. The tooth grooves of the second driving wheel mesh with the inner rack of the crawler assembly, and the meshing depth is 5 - 7 mm, and the meshing angle is 20°.

[0048] The first support wheel is located on the left side of the front end of the frame body, opposite to the first drive wheel, and the center distance between the two is 700 - 800 mm. The first support wheel is made of 6061-T6 high-strength aluminum alloy material, in a circular disc structure, with a diameter of 180 - 220 mm and a thickness of 25 - 35 mm. The outer peripheral surface of the first support wheel is smooth without tooth grooves, the surface roughness Ra value does not exceed 1.6 μm, the surface is treated by anodic oxidation, and the thickness of the oxide film is 10 - 15 μm. A circular shaft hole is provided at the center of the first support wheel, with a shaft hole diameter of 18 - 22 mm, and the shaft hole tolerance fit is H7 / j6. The first support wheel is rotationally connected to the left front mounting hole of the frame body through a deep groove ball bearing, and the bearing model is 6004-2RZ. The outer peripheral surface of the first support wheel is in smooth contact with the inner side of the crawler assembly, and the contact pressure is 50 - 80 N / cm.

[0049] The second support wheel is located on the left side of the rear end of the frame body, opposite to the second drive wheel, and is made of the same 6061-T6 high-strength aluminum alloy material as the first support wheel. The structural parameters of the second support wheel are exactly the same as those of the first support wheel, including a diameter of 180 - 220 mm, a thickness of 25 - 35 mm, and a shaft hole diameter of 18 - 22 mm. The second support wheel is rotationally connected to the left rear mounting hole of the frame body through a deep groove ball bearing of the same specification. The outer peripheral surface of the second support wheel is in smooth contact with the inner side of the crawler assembly, and is used to support the rear part of the crawler assembly and maintain an appropriate tension state of the crawler assembly.

[0050] The crawler assembly is made of a mixed material of natural rubber and synthetic rubber, with a rubber hardness of Shore A 70 - 80 degrees. Steel cord is added inside as a skeleton material, with a steel wire diameter of 1.0 mm and a tensile strength of not less than 1570 MPa. The crawler assembly is in a continuous annular belt structure, with a total length of 3000 - 3400 mm, a width of 140 - 160 mm, and a thickness of 20 - 30 mm. A rack structure matching the tooth grooves of the first drive wheel and the second drive wheel is provided on the inner side of the crawler assembly. The tooth pitch of the rack is 32 - 38 mm, the tooth height is 5 - 7 mm, and the tooth profile angle is 20°. The rack is made by a molding process, and the surface hardness is 5 - 10 degrees higher than that of the crawler body. Anti-slip patterns are provided on the outer side of the crawler assembly, with a pattern depth of 3 - 5 mm, a pattern spacing of 25 - 30 mm, and the pattern area accounting for 40% - 60% of the total outer surface area. The crawler assembly is arranged around the first drive wheel, the second drive wheel, the first support wheel, and the second support wheel, and moves along a circular path under the drive of the first drive wheel and the second drive wheel.

[0051] The first driving motor is fixedly installed inside the right front end of the vehicle frame main body and adopts a permanent magnet synchronous DC brushless motor with the model of BLM-1500-24V. The rated power of the first driving motor is 1200-1800W, the rated speed is 1600-2000r / min, the rated torque is 8-12N·m, and the efficiency is not less than 85%. The motor housing is made of aluminum alloy material, the protection level is IP65, and the working temperature range is -20°C to 60°C. The output shaft of the first driving motor is connected to the shaft hole of the first driving wheel through the first transmission connecting shaft. The first transmission connecting shaft is made of 45# high-quality carbon structural steel, and the hardness reaches HRC35-40 after quenching and tempering treatment. It has a cylindrical structure, the diameter is 23-27mm, and the length is 100-140mm. Key grooves are respectively arranged at both ends of the first transmission connecting shaft, the depth of the key groove is 4-6mm, the width is 6-10mm, the specification of the key is 8×7×32mm, and the fit tolerance is H9 / d9. The first driving motor drives the first driving wheel to rotate through the first transmission connecting shaft, and the transmission efficiency reaches more than 98%.

[0052] The second driving motor is fixedly installed inside the right rear end of the vehicle frame main body and adopts a permanent magnet synchronous DC brushless motor with the same specifications as the first driving motor. The technical parameters of the second driving motor are exactly the same as those of the first driving motor, including the rated power of 1200-1800W and the rated speed of 1600-2000r / min. The output shaft of the second driving motor is connected to the shaft hole of the second driving wheel through the second transmission connecting shaft. The second transmission connecting shaft is made of the same 45# steel material as the first transmission connecting shaft, and the structural parameters are exactly the same. The second driving motor drives the second driving wheel to rotate through the second transmission connecting shaft, and the difference between the speed of the second driving motor and the speed of the first driving motor is used to adjust the tension state of the track assembly.

[0053] The tension adjustment mechanism mainly includes a tension detection device and a speed adjustment device. The tension detection device is arranged above the track assembly between the first support wheel and the second support wheel, 5-10mm away from the track surface. The tension detection device includes a pressure sensing rod and an elastic reset element. The pressure sensing rod is made of 304 stainless steel material, the tensile strength is not less than 520MPa, it has a slender rod-like structure, the length is 160-200mm, the diameter is 6-10mm, and the surface roughness Ra value does not exceed 0.8μm. One end of the pressure sensing rod is processed into a hemispherical shape and contacts the outer surface of the track assembly, and the contact area is 15-25mm 2The other end of the pressure sensing rod is connected to the elastic reset element. The connection method is threaded connection, and the thread specification is M8×1.25. The elastic reset element is a compression spring made of 65Mn spring steel. The free length of the spring is 50 - 70 mm, the wire diameter is 1.5 - 2.5 mm, the outer diameter is 16 - 20 mm, the number of effective turns is 8 - 12 turns, and the elastic modulus is 206 GPa. When the tension of the crawler assembly increases, the downward movement distance of the pressure sensing rod increases, and the compression amount of the elastic reset element increases accordingly. The compression amount and the tension change show a linear relationship.

[0054] The speed regulating device includes a mechanical governor and a transmission gear set. The mechanical governor works on the principle of centrifugal speed regulation and realizes automatic regulation through the change of centrifugal force when the speed changes. The main body of the mechanical governor is made of HT200 gray cast iron material, with a hardness of HB170 - 220. It has a cylindrical structure, a diameter of 70 - 90 mm, a height of 50 - 70 mm, and a wall thickness of 8 - 12 mm. There are two symmetrically distributed centrifugal blocks inside the mechanical governor. The centrifugal blocks are made of QSn6.5 - 0.1 phosphor bronze alloy material. The mass of each centrifugal block is 120 - 180 g, and the external dimensions are 30 mm in length, 20 mm in width, and 15 mm in thickness. The centrifugal blocks are connected to the central axis of the mechanical governor through a hinge shaft. The material of the hinge shaft is 40Cr steel, with a diameter of 8 mm and a length of 25 mm. When the speed of the mechanical governor changes, the centrifugal force received by the centrifugal blocks changes accordingly. The centrifugal force calculation formula is F = mω 2 r, where m is the mass of the centrifugal block, ω is the angular velocity, and r is the rotation radius. The position change of the centrifugal block drives the adjusting rod to move. The adjusting rod is made of 45 steel, with a diameter of 12 mm and a length of 80 mm. The movement of the adjusting rod changes the transmission ratio of the transmission gear set. The movement stroke range of the adjusting rod is limited between 5 - 15 mm.

[0055] The transmission gear set includes a driving gear and a driven gear. The gear material is 20CrMnTi carburized steel. After carburizing and quenching treatment, the surface hardness reaches HRC58 - 62, and the core hardness is HRC30 - 40. The number of teeth of the driving gear is 18 - 22, the module is 2.5mm, the pressure angle is 20°, and the tooth width is 25mm. The number of teeth of the driven gear is 22 - 26, the module is 2.5mm, the pressure angle is 20°, and the tooth width is 25mm. The precision grade of the gear is grade 7, and the Ra value of the tooth surface roughness does not exceed 1.6μm. The meshing depth constraint of the transmission gear set requires that the standard meshing state be maintained between the addendum circle and the dedendum circle of the driving gear and the driven gear. The proportion of the meshing depth in the tooth height must be controlled within the range of 60% - 80%. The center distance of the gear pair is 46 - 52mm, and the center distance deviation shall not exceed 0.2mm. When the transmission ratio changes, the meshing point position of the gears must always be kept on the theoretical meshing line of the gear pair, and the tooth surface contact stress distribution must be uniform without local stress concentration.

[0056] The core constraint relationship of the entire drive structure is the control of the rotational speed difference between the first drive wheel and the second drive wheel. When the first drive wheel and the second drive wheel perform differential motion, the rotational speed difference between the two drive wheels must be controlled within the specified range, and the tension adjustment response of the crawler assembly must be linearly related to the speed difference. The constraint relationship of the rotational speed difference between the first drive wheel speed and the second drive wheel speed is specifically expressed as follows: Δn = n1 - n2 = k·ΔT + C, where Δn is the rotational speed difference between the two drive wheels, with the unit of r / min; n1 is the first drive wheel speed; n2 is the second drive wheel speed; ΔT is the tension difference between the front and rear sections of the crawler assembly, with the unit of N; k is the speed - tension coupling coefficient, and the numerical range is 8 - 12; C is the system compensation constant, and the value range is 15 - 25, which is used to compensate for the mechanical transmission loss and frictional resistance of the system.

[0057] The specific usage method of the device is as follows: First, start the first drive motor and the second drive motor to make the two drive wheels start to rotate in the same direction. When the first drive wheel rotates clockwise and its speed is higher than that of the second drive wheel, the tension of the front section of the crawler assembly increases. At this time, the pressure sensing rod of the tension detection device moves downward, and the elastic reset element is compressed. When the compression amount of the elastic reset element exceeds the preset value of 18 - 22mm, the speed adjustment device starts to work. The mechanical governor responds to the tension change, and the radial displacement of the centrifugal block is proportional to the square of the governor speed. The adjustment force generated by the movement of the centrifugal block is accurately transmitted to the transmission gear set through the adjustment rod, and the transmission ratio of the transmission gear set changes, thereby reducing the speed of the second drive motor to be lower than that of the first drive motor and reducing the tension of the crawler assembly. When the speed of the second drive wheel is higher than that of the first drive wheel, the tension of the rear section of the crawler assembly increases, and the tension of the front section decreases accordingly. The system will automatically adjust to make the speeds of the two drive wheels tend to be balanced.

[0058] During actual use, the installation accuracy requirements for the first driving wheel and the second driving wheel are extremely strict. The installation position of the second driving wheel must be accurately aligned with the reference line on the right side of the rear end of the vehicle frame main body. The parallelism deviation between the axes of the two driving wheels shall not exceed 0.5 mm, and the distance deviation between the axes shall not exceed 0.1% of the designed length of the track assembly. The meshing depth between the inner rack structure of the track assembly and the rectangular tooth grooves of the first driving wheel is 5 - 7 mm, and the meshing depth between the inner rack structure of the track assembly and the rectangular tooth grooves of the second driving wheel is also 5 - 7 mm. The meshing surface must be kept clean, free of oil stains and impurities. When the first driving wheel rotates clockwise and its rotational speed is higher than that of the second driving wheel, the increase amplitude of the tension in the front section of the track assembly must be controlled within the preset threshold range, and the ratio of the tension increase rate to the rotational speed difference must be maintained within the range of 0.8 - 1.2. When the mechanical governor responds to the tension change and executes the automatic adjustment function, when the movement stroke range of the adjustment rod exceeds 5 - 15 mm, the system automatically locks to prevent over-adjustment.

[0059] When the entire device is working, the track assembly moves along an annular path driven by the two driving wheels, and the two supporting wheels play a role in supporting and guiding. By precisely controlling the rotational speed difference between the two driving wheels, the real-time adjustment of the track tension is achieved, so that the track always maintains the best tension state. The response time of the tension adjustment system is 0.1 - 0.3 s, the transmission efficiency reaches more than 92%, and the running noise is controlled below 65 dB. When the device needs to turn, differential steering can be achieved by adjusting the rotational speed difference between the two driving wheels, and the turning radius can be adjusted according to the magnitude of the rotational speed difference. The entire drive structure is designed compactly and is convenient for maintenance, and is suitable for stretcher transportation operations under various complex terrain conditions.

[0060] It should be noted that the differential control technology of the dual driving wheels is the core innovative idea of the present invention. This technology forms a power transmission mode of double-point drive by respectively arranging the independently driven first driving wheel and the second driving wheel at the front and rear ends of the tracked vehicle. Compared with the technical solution of the traditional single driving wheel cooperating with the passive supporting wheel, the dual driving wheel system can independently control the traction force distribution of the front and rear sections of the track. When the vehicle encounters a complex terrain with an increased resistance ahead, the first driving wheel can provide a greater driving force, while the second driving wheel reduces the tension loss of the rear section of the track by reducing the rotational speed, thereby realizing the active redistribution of the internal stress field of the track. This differential control mechanism fundamentally changes the passive adaptation mode of the track tension, enabling the track system to actively adjust the tension state of each section according to the actual working conditions, and significantly improving the traction performance and passing ability of the tracked vehicle on uneven terrains.

[0061] The mechanical tension adjustment mechanism adopts the principle of pure mechanical feedback control. It can detect the change of track tension in real time through a pressure sensing rod, and use an elastic reset element to convert the mechanical signal into a mechanical displacement signal, driving a centrifugal governor to adjust the speed of the second drive motor. Compared with the traditional electronically controlled tension adjustment system, the mechanical adjustment mechanism has the significant advantages of fast response speed and high reliability. The change of centrifugal force generated by the centrifugal blocks inside the centrifugal governor when the speed changes can directly drive the transmission gear set to change the transmission ratio. The whole adjustment process does not require a complex electronic control unit and sensor network, avoiding the fault problems that are prone to occur in the electronically controlled system under harsh environments. The adaptive characteristics of the mechanical adjustment mechanism enable the system to maintain stable adjustment performance under various extreme working conditions, ensuring that the track tension is always in the best state.

[0062] The linear constraint control algorithm establishes an accurate mathematical relationship between the rotational speed difference and the tension difference. By introducing the rotational speed-tension coupling coefficient and the system compensation constant, the quantitative control of track tension adjustment is realized. Compared with the traditional empirical adjustment method, the linear constraint algorithm provides predictable and repeatable control results. This algorithm takes into account the elastic characteristics of the track material, geometric parameters, and energy losses during the mechanical transmission process, ensuring the linear correspondence between rotational speed adjustment and tension change. This quantitative control mode eliminates the common problems of over-adjustment or under-adjustment in traditional systems, enabling the track tension to accurately follow the changes in working conditions for real-time adjustment, so as to obtain the optimal traction effect under various terrain conditions.

[0063] The synergistic effect of the three key technical ideas forms a complete intelligent track tension adjustment system, achieving a qualitative leap compared with the existing technology. The differential control of the double drive wheels provides the physical basis for tension adjustment, the mechanical adjustment mechanism provides a reliable feedback control means, and the linear constraint algorithm ensures the accuracy and stability of the adjustment process. The organic combination of the three enables the tracked vehicle to autonomously adapt to complex and changeable terrain conditions and maintain the best driving state without manual intervention. This synergistic effect not only solves the fundamental problems of insufficient traction and unstable driving of traditional tracked vehicles in complex terrains, but more importantly, establishes a complete theoretical system for intelligent track tension adjustment, providing a new technical path and solution for the development of tracked vehicle technology.

[0064] Specifically, the principle of the present invention is as follows: The core principle of the technical solution of the present invention to solve the problem of dynamic adjustment of track tension lies in establishing an accurate mechanical relationship between the differential speed control of the two drive wheels and the track tension distribution. As a continuous annular elastic body, the internal tension distribution of the track is directly affected by the rotational speed difference of the drive wheels. When the rotational speed of the first drive wheel is higher than that of the second drive wheel, the front section of the track receives a greater traction force, and this section of the track is tightened, resulting in a natural increase in tension; at the same time, the traction force received by the rear section of the track is relatively reduced, and the tension decreases accordingly. This process of tension redistribution follows the principle of stress distribution in material mechanics. By controlling the speed difference between the two drive points, precise regulation of the internal stress field of the entire track system is achieved.

[0065] The working principle of the mechanical tension adjustment mechanism is based on the perfect combination of centrifugal speed regulation and gear transmission. The pressure sensing rod in the tension detection device directly contacts the track surface, and can real-time sense the change of track tension and transmit the mechanical signal to the mechanical speed regulator through the elastic reset element. The centrifugal blocks inside the speed regulator generate different centrifugal forces when the rotational speed changes. The change of the centrifugal force drives the adjustment rod to move, thereby changing the meshing state and transmission ratio of the transmission gear set. This purely mechanical feedback control system eliminates the delay and instability factors of the electronic control system, and can complete the tension adjustment response within milliseconds.

[0066] The constraint relation Δn=n1 - n2=k·ΔT + C of the present invention establishes a quantitative mathematical model between the rotational speed difference and the tension difference. Among them, the rotational speed-tension coupling coefficient k reflects the influence of the track material characteristics and geometric parameters on the tension transmission efficiency, and the system compensation constant C takes into account the friction loss and elastic deformation in the mechanical transmission process. This linear constraint relation ensures the accuracy and predictability of tension adjustment, and avoids the problems of over-adjustment or under-adjustment commonly seen in traditional systems. The strict control of the gear meshing depth and the axis parallelism further ensures the accuracy of power transmission and eliminates the system instability caused by mechanical errors. Through this multi-level constraint and control mechanism, the present invention realizes the intelligent dynamic adjustment of track tension, and fundamentally solves the traction force and stability problems of tracked vehicles in complex terrains.

[0067] The following provides a specific embodiment 1 implemented by the rotational speed difference constraint relation of the present invention. The specific implementation manners of each step in this embodiment 1 are described in detail as follows.

[0068] The specific implementation of the rotational speed difference constraint relationship Δn = n1 - n2 = k·ΔT + C depends on a set of precise mechatronic control systems, which are achieved through the coordinated operation of four core components: a tension measurement device, a rotational speed monitoring mechanism, a mechanical governor, and a feedback adjustment loop. The tension measurement device is the basis for the implementation of the entire constraint relationship. A distributed tension detection scheme is adopted, and independent tension sensor components are respectively set at the front and rear sections of the track assembly. The front-section tension sensor is installed above the upper surface of the track between the first drive wheel and the first support wheel. A non-contact magnetostrictive displacement sensor is used in combination with an elastic beam structure. The elastic beam is made of 40CrNiMo alloy steel, with a length of 200 mm, a rectangular cross-section of 15 mm×8 mm, and an elastic modulus of 206 GPa. When the track tension changes, the vertical displacement of the track is transmitted to the elastic beam through a contact rod, and the minute deformation of the elastic beam is accurately detected by the magnetostrictive sensor, with a measurement accuracy of ±5 N and a response time of no more than 0.05 s. The rear-section tension sensor adopts the same structure and technical parameters and is installed below the lower surface of the track between the second drive wheel and the second support wheel. By arranging symmetrically, the consistency and comparability of the front and rear section tension measurements are ensured.

[0069] The rotational speed monitoring mechanism adopts a dual detection scheme of a high-precision optoelectronic encoder and a magnetoelectric rotational speed sensor to ensure the accuracy and reliability of rotational speed measurement. The rotational speed monitoring of the first drive wheel is achieved through a 1024-line optoelectronic encoder installed on the first transmission connecting shaft. The encoder housing is designed with an IP67 protection level, with an operating temperature range of -40°C to 85°C and a measurement accuracy of ±0.1 r / min. The pulse signal output by the encoder is sent to the rotational speed calculation unit through a differential signal transmission method to avoid the influence of external electromagnetic interference on the measurement accuracy. The second drive wheel uses an optoelectronic encoder of the same specification for rotational speed monitoring, and the installation positions of the two encoders are accurately calibrated to ensure the consistency of the measurement reference. The magnetoelectric rotational speed sensor is used as a backup detection means and is installed at the outer peripheral position of the drive wheel. The rotational speed is calculated by detecting the passing frequency of the drive wheel tooth grooves, providing redundant protection for the optoelectronic encoder.

[0070] The mechanical governor is the core actuator for realizing the automatic adjustment of the rotational speed difference. Its working principle is based on the balance relationship between centrifugal force and spring force. Two symmetric centrifugal blocks set inside the governor body are affected by centrifugal force during rotation. The magnitude of the centrifugal force is directly proportional to the square of the rotational speed, and the expression is F 离心 = mω 2r, where m is the mass of the centrifugal block, which is 180 g, ω is the angular velocity, and r is the radius of rotation, which is 45 mm. When the rotational speed of the second driving motor changes, the radial displacement of the centrifugal block changes accordingly. The relationship between the displacement and the rotational speed has been accurately calibrated to ensure good linear characteristics within the operating speed range of 1600 - 2000 r / min. The radial movement of the centrifugal block is transmitted to the adjusting slider through a linkage mechanism. The adjusting slider is constrained in its movement direction by a ball guide rail. The axial displacement of the slider directly controls the meshing depth of the transmission gear set, thereby changing the transmission ratio. The transmission gear set is designed with variable tooth thickness helical gears. The tooth thickness of the driving gear changes linearly along the axial direction, from 18 mm to 12 mm, and the tooth thickness of the driven gear changes correspondingly from 12 mm to 18 mm. When the adjusting slider moves 5 mm, the transmission ratio changes from 1.0 to 1.5, achieving a speed adjustment range of ±25% of the rated speed.

[0071] The determination of the rotational speed - tension coupling coefficient k depends on the calibration of the mechanical characteristics of the system and the fitting of experimental data. By conducting static and dynamic tension tests on the track assembly on a standard test bench, a mathematical model between the tension change and the rotational speed difference is established. During the test process, the tension at the front section of the track is gradually increased from 500 N to 1500 N, with an increment of 100 N each time, while recording the corresponding changes in the rotational speed difference. After fitting the experimental data using the least - squares method, the statistical distribution of the k value is obtained. The variation range of the k value under different track materials and working conditions is 8 - 12. The specific calibration of the k value adopts a multi - condition verification method, including tests under different load conditions, where the load changes from 0 kg to 200 kg with an increment of 50 kg each time; tests under different ground conditions, including hard roads, gravel roads, sandy roads, and muddy roads; and tests under different environmental temperatures, with the temperature range from - 10°C to 40°C. By comprehensively analyzing the test data under various conditions, the optimal setting range of the k value is determined and solidified in the control algorithm.

[0072] The value of the system compensation constant C is determined based on the loss analysis of the mechanical transmission system and the test results of the friction characteristics. The main losses of the transmission system include bearing friction loss, gear meshing loss, sliding friction loss between the crawler and the ground, and air resistance loss. The bearing friction loss is calculated through the friction torque data provided by the bearing manufacturer. The friction torque of the deep groove ball bearing 6205-2RZ under the rated load is 0.8 N·m, and the corresponding power loss is approximately 150 W. The gear meshing loss is determined through the gear transmission efficiency test. The transmission efficiency of the 7th precision gear pair under the standard load is 97%, and the loss power is approximately 45 W. The sliding friction loss between the crawler and the ground is greatly affected by the ground conditions. The sliding friction coefficient is 0.05 on the hard road surface and can reach 0.15 on the sandy soil road surface, and the corresponding power loss range is 80-240 W. Based on the comprehensive calculation of various losses, the theoretical calculated value of the system compensation constant C is 18-22. Considering the complexity of the actual working conditions and the safety margin, the value range of C is extended to 15-25.

[0073] The feedback regulation loop uses the proportional-integral-derivative control algorithm to achieve the precise correspondence between the tension difference and the speed difference. The mathematical expression of the control algorithm is where u(t) is the control output signal, e(t) is the deviation between the tension difference and the target value, and K p , K i , K d are the proportional, integral, and derivative gain coefficients respectively. The input signal of the controller is the tension difference ΔT measured in real time, and the output signal is the speed adjustment command of the second drive motor. In order to ensure the linear characteristics of the constraint relationship, a linearization compensation link is added to the control algorithm to eliminate the influence of non-linear factors through the method of look-up table interpolation. The setting of the proportional gain K p is based on the steady-state accuracy requirement of the system, and the value is 0.8 to ensure that the steady-state error does not exceed ±3%. The setting of the integral gain K i is based on the dynamic response requirement of the system, and the value is 0.3 to ensure that the adjustment time does not exceed 0.3 s. The setting of the derivative gain K d is based on the stability requirement of the system, and the value is 0.1 to ensure that the overshoot does not exceed 10%.

[0074] The maintenance of the linear relationship depends on the accuracy guarantee of each link in the system and the effective compensation of non-linear factors. The non-linearity of the tension measurement link mainly comes from the large deformation effect of the elastic beam and the hysteresis characteristic of the sensor. By adopting the small deformation hypothesis in the design of the elastic beam and controlling the maximum strain within 50% of the elastic limit, the linear relationship between force and deformation is ensured. The hysteresis error of the sensor is eliminated by means of multi-point calibration and software compensation. The number of calibration points is not less than 20, covering the entire measurement range, and the compensation accuracy reaches ±1%. The non-linearity of the rotational speed measurement link mainly comes from the resolution limitation of the encoder and the signal processing delay. By adopting a high-resolution encoder and a hardware signal processing circuit, the measurement error is controlled within ±0.05%. The non-linearity of the mechanical governor mainly comes from the movement trajectory deviation of the centrifugal block and the geometric error of gear meshing. By ensuring the geometric accuracy of each part through precision machining and assembly processes, the overall non-linear error is controlled within ±2%.

[0075] In the actual implementation process, the establishment of the constraint relationship needs to go through four stages: initialization, calibration, operation, and maintenance. In the initialization stage, the zero calibration of each sensor and the initial setting of system parameters are mainly completed, including the zero drift compensation of the tension sensor, the phase synchronization of the rotational speed sensor, and the initial value setting of the control algorithm parameters. In the calibration stage, the specific values of the k value and the C value are determined through actual tests under different working conditions, the corresponding look-up table of tension and rotational speed is established, and the effectiveness of the linear relationship is verified. In the operation stage, the system automatically adjusts according to the established constraint relationship, monitors the changes of each parameter in real time, and automatically starts the correction program when the detected deviation exceeds the allowable range. In the maintenance stage, the working status of each component is regularly checked, and the system parameters are recalibrated to ensure the long-term stability and reliability of the constraint relationship. The implementation accuracy of the entire constraint relationship reaches ±5% under normal working conditions and remains within ±8% under extreme working conditions, meeting the usage requirements of the stretcher tracked vehicle under various environmental conditions.

[0076] To better understand and implement the present invention, the following provides an embodiment 2 of a specific application scenario of the present invention: Researchers conduct implementation verification on the tracked drive structure of the stretcher tracked vehicle in a flat hard ground environment. This embodiment aims at the flat ground transfer requirement in the medical first aid scenario. The main body of the frame adopts a rectangular frame structure with a length of 1200 mm, a width of 800 mm, and a height of 300 mm, and is made of 6061-T6 aluminum alloy material. The first driving wheel is set with a diameter of 260 mm, a thickness of 40 mm, and 28 rectangular tooth grooves are evenly distributed on the outer periphery. The depth of each tooth groove is 8 mm and the width is 12 mm. The diameter of the second driving wheel is set to 240 mm, the thickness is 40 mm, and 24 rectangular tooth grooves are arranged on the outer periphery. The tooth groove specifications are the same as those of the first driving wheel. The diameters of the first supporting wheel and the second supporting wheel are both set to 200 mm, the thickness is 30 mm, and they are made of the same aluminum alloy material.

[0077] The total length of the crawler assembly is set to 3200 mm, the width is 150 mm, the thickness is 25 mm, the pitch of the inner rack teeth is 35 mm, and the tooth height is 6 mm. The rated power of the first drive motor is set to 1500 W, and the rated speed is 1800 r / min. The parameters of the second drive motor are exactly the same as those of the first drive motor. The length of the pressure sensing rod in the tension adjusting mechanism is 180 mm, the diameter is 8 mm, the free length of the elastic reset element is 60 mm, and the wire diameter is 2.0 mm. The mechanical speed governor has a diameter of 80 mm and a height of 60 mm, and the mass of each internal centrifugal block is 150 g. In the transmission gear set, the number of teeth of the driving gear is 20, the number of teeth of the driven gear is 24, and the transmission ratio is 1.2.

[0078] During the installation process, the researchers first placed the main frame body on a horizontal tabletop and used a precision level to ensure that the deviation of the frame levelness does not exceed 0.2 mm. Subsequently, the first drive wheel was installed, and the concentricity deviation between the shaft hole and the frame mounting hole was controlled within 0.1 mm through a fixture. Special attention should be paid to the parallelism of the axis of the second drive wheel with that of the first drive wheel during installation. A laser alignment instrument was used to measure the parallelism deviation of the two axes to ensure that the deviation does not exceed 0.3 mm. The installation of the support wheel is relatively simple, but it is necessary to ensure that the contact pressure on the outer peripheral surface of the support wheel is evenly distributed with the inner side of the crawler. For the installation of the crawler assembly, it is necessary to first put it on the four wheels, and then adjust the tension detection device so that the contact pressure between the pressure sensing rod and the crawler surface is 60 N.

[0079] During the use process, the researchers placed the crawler vehicle on a flat concrete road surface with a length of 50 m for testing. The two drive motors were started, and the initial speeds were both set to 1500 r / min, and the crawler vehicle started to move forward smoothly. When steering was required, the speed of the first drive motor was adjusted to 1600 r / min, and the second drive motor remained at 1500 r / min, with a speed difference of 100 r / min. The crawler vehicle achieved a right turn with a radius of 8 m. During the straight-line driving process, the tension detection device monitored that the tension in the front section of the crawler was 800 N, the tension in the rear section was 750 N, and the tension difference was 50 N. According to the constraint relationship Δn = k·ΔT + C, taking k = 10 and C = 20, the calculated theoretical speed difference was 520 r / min, but the actually measured speed difference was only 100 r / min, indicating that the change in the crawler tension on the flat ground was small and the speed adjustment range was limited for the system.

[0080] Example 3: The research team conducted a heavy-load adaptability test on the track drive structure of the stretcher tracked vehicle in a rugged mountain environment. In response to the complex terrain requirements in mountain rescue, the frame body size was adjusted to a length of 1300 mm, a width of 850 mm, and a height of 320 mm to obtain a larger load-bearing space and stronger structural rigidity. The diameter of the first drive wheel was increased to 270 mm, the thickness was increased to 45 mm, and 30 rectangular tooth grooves were provided on the outer periphery to provide stronger driving force. The diameter of the second drive wheel was set to 250 mm, the thickness was 45 mm, and 26 rectangular tooth grooves were provided on the outer periphery. The diameters of the support wheels were all set to 220 mm, and the thickness was increased to 35 mm to withstand greater loads.

[0081] The length of the track assembly was adjusted to 3400 mm, the width remained 150 mm, and the thickness was increased to 30 mm to improve wear resistance and load-bearing capacity. The tooth pitch of the inner rack was set to 38 mm, and the tooth height was increased to 7 mm to ensure reliable meshing with the drive wheel. The power of the first drive motor was increased to 1800 W, the rated speed was set to 2000 r / min, and the parameters of the second drive motor were the same. The wire diameter of the elastic reset element in the tension adjustment mechanism was increased to 2.5 mm, and the mass of each centrifugal block was increased to 180 g to provide a greater adjustment torque.

[0082] The research team selected a gravel mountain road with a slope of 15° and a length of 100 m for testing. The road surface contained irregular stones with diameters ranging from 50 to 200 mm. During the installation process, special attention was paid to the parallelism of the axes of the drive wheels and the support wheels, and a coordinate measuring machine was used to ensure that the parallelism deviation was controlled within 0.2 mm. After the track assembly was installed, the initial tension was set to 1200 N through the tension adjustment mechanism, which was 50% higher than that during the flat ground test. During the driving process on the rugged road surface, the tracked vehicle carried a load of 150 kg to simulate the weight of the stretcher and the wounded. During the test, the tension fluctuation range of the front section of the track was 1000 - 1500 N, the tension fluctuation range of the rear section was 900 - 1400 N, and the maximum tension difference reached 600 N. At this time, the rotational speed of the first drive motor was automatically adjusted to 1900 r / min, the rotational speed of the second drive motor was adjusted to 1200 r / min, and the rotational speed difference reached 700 r / min, effectively maintaining the stable operation of the track.

[0083] The key performance data in the mountain test are shown in Table 1:

[0084] Table 1 Data Sheet of Track Performance Test in Mountain Environment

[0085] Test item Numerical range Average value Standard deviation Tension of the front section of the crawler (N) 1000～1500 1250 125 Tension of the rear section of the crawler (N) 900～1400 1150 118 Rotational speed of the first drive wheel (r / min) 1800～2000 1900 45 Rotational speed of the second drive wheel (r / min) 1100～1300 1200 52 Tension adjustment response time (s) 0.08～0.25 0.15 0.04 Crawler slip rate (%) 0～3.2 1.8 0.8

[0086] After six hours of continuous mountain testing, the research team discovered that the dual-drive wheel differential control system can automatically adjust track tension according to terrain changes, effectively preventing track derailment and slippage. When the tracked vehicle passes over large rocks, the tension adjustment mechanism responds within 0.1 to 0.3 seconds, ensuring that the track maintains optimal tension.

[0087] Example 4: Researchers conducted extreme operating condition tests on the track drive structure of a stretcher crawler vehicle in sandy and muddy environments. This example addresses the special needs of desert rescue and muddy roads in the rainy season, requiring the track to have stronger sand and mud resistance and more precise tension control. The frame body adopts the standard size of 1200mm×800mm×300mm, but sealing structures are added at key locations to prevent sand and soil intrusion. The tooth groove depth of the first and second drive wheels is reduced to 7mm, and the width is increased to 14mm. The tooth groove surface is treated with a special coating to reduce sand and soil adhesion. The depth of the anti-slip pattern on the outside of the track assembly is increased to 5mm, and the pattern spacing is reduced to 20mm to improve grip on soft ground.

[0088] The tension adjustment mechanism features a specially designed design. A rubber sleeve is installed on the pressure sensing rod to prevent abrasion from sand and dirt, and a protective cover is added around the elastic reset element. The centrifugal mass of the mechanical speed regulator has been adjusted to 120g to increase sensitivity to slight tension changes. The transmission gear set is fully sealed, and the gear surfaces are nitrided for improved wear resistance. The drive motor housing has been upgraded to IP67 protection, ensuring reliable operation in harsh environments.

[0089] The researchers conducted tests on a clay road surface with a moisture content of 25% and on a fine sand road surface with an average particle size of 0.5mm. In the muddy road test, the coefficient of friction between the track assembly and the ground was reduced to 0.3, and the track was prone to slipping. By precisely controlling the speed difference between the two drive wheels, the speed of the first drive wheel was set to 1400r / min and the speed of the second drive wheel was set to 1350r / min, with a speed difference of only 50r / min, effectively preventing the increase in energy consumption caused by excessive track tension. In the sand test, due to the fluidity of the sand, the track sank to a depth of 50-80mm, at this time, the track tension needed to be increased to provide sufficient buoyancy. The tension adjustment mechanism automatically adjusted the tension of the front section of the track to 1100N and the tension of the rear section to 1050N, ensuring that the track vehicle could pass through the sand area stably.

[0090] The environmental adaptability data recorded during the extreme condition test shows that the tension adjustment accuracy of the dual-drive wheel differential control system reaches ±15 N in sandy environments and ±20 N in muddy environments. Compared with the single-drive wheel system, the probability of track derailment is reduced by 18%, and the energy consumption is reduced by 12%. The tension adjustment response time can still be maintained within 0.2 s in harsh environments, which is 15% faster than the traditional electric control system. The mechanical speed governor operates continuously for 48 hours without failure in sandy and dusty environments, demonstrating the high reliability of the system.

[0091] Traditional stretcher crawler vehicles mostly adopt a structure with a single drive wheel and multiple passive support wheels. The track tension is mainly pre-adjusted by a mechanical tensioning device and cannot be adjusted in real time during driving. When encountering complex terrains, the fixed tension setting often cannot adapt to the changes in ground conditions, easily leading to track slippage, derailment, or excessive wear. Although the traditional electric control tension adjustment system can achieve dynamic adjustment, its response speed is slow, usually taking 0.5 - 1.0 s to complete the adjustment action, and it is prone to electric control system failures in harsh environments. The dual-drive wheel differential control system adopted in the present invention realizes real-time and precise control of track tension through a mechanical tension adjustment mechanism, and the response time is shortened to 0.1 - 0.3 s, which is 20% faster than the traditional electric control system. The track derailment rate in complex terrains is reduced by 18%, the transmission efficiency is increased by 8%, and the operating noise is reduced by 12 dB. The mechanical speed governor does not rely on the electric control system, and its reliability in harsh environments such as sandy and humid conditions is 15% higher than that of the traditional electric control system, and the maintenance cycle is extended by 25%. The dual-drive wheel structure also provides a differential steering function, and the turning radius is reduced by 20% compared with the traditional structure, greatly improving the maneuverability of the stretcher crawler vehicle in narrow spaces.

[0092] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A driving structure of a crawler for a stretcher crawler vehicle, characterized in that, It includes a frame body and a crawler assembly. The frame body is made of high-strength aluminum alloy material and is in a rectangular frame structure. Circular mounting holes are provided at the four corners of the frame body. The crawler assembly is arranged around the outer periphery of the frame body. It further includes: a driving wheel, which is divided into a first driving wheel and a second driving wheel. The first driving wheel and the second driving wheel are respectively arranged at the front and rear ends of the frame body. The first driving wheel is rotatably connected to the front mounting hole of the frame body through a bearing. The tooth grooves of the first driving wheel are engaged with the inner rack of the crawler assembly to provide the main driving force for the forward movement of the crawler assembly; a second driving wheel, located at the rear end of the frame body. The second driving wheel is rotatably connected to the rear mounting hole of the frame body through a bearing. The tooth grooves of the second driving wheel are engaged with the inner rack of the crawler assembly to provide the auxiliary driving force and tension adjustment function for the crawler assembly; a first support wheel and a second support wheel, both arranged inside the first driving wheel and the second driving wheel for support; a first driving motor and a second driving motor, respectively driving the first driving wheel and the second driving wheel to rotate; a tension adjustment mechanism, which realizes the automatic adjustment of the tension of the crawler assembly by adjusting the rotation speed of the second driving motor, and realizes the precise dynamic adjustment of the crawler tension by establishing a linear relationship between the speed difference and the tension difference through the differential control of the two driving wheels.

2. The drive structure of the crawler of a stretcher crawler vehicle according to claim 1, characterized in that The first driving wheel is made of high-strength steel and is in a circular disc structure. Uniformly distributed rectangular tooth grooves are provided on the outer periphery of the first driving wheel. A circular shaft hole is provided at the center of the first driving wheel. The rectangular tooth grooves are used for precise meshing transmission with the inner rack of the crawler assembly.

3. The drive structure of the crawler of a stretcher crawler vehicle according to claim 2, characterized in that, The second driving wheel is made of the same high-strength steel as the first driving wheel and is in a circular disc structure. Uniformly distributed rectangular tooth grooves are provided on the outer periphery of the second driving wheel. A circular shaft hole is provided at the center of the second driving wheel. When there is a difference in the rotation speed between the second driving wheel and the first driving wheel, the tension state of the crawler assembly changes accordingly.

4. The drive structure of the crawler of a stretcher crawler vehicle according to claim 3, characterized in that, The first driving motor is fixedly installed inside the right side of the front end of the frame body. The first driving motor is a DC brushless motor. The output shaft of the first driving motor is connected to the shaft hole of the first driving wheel through a first transmission connecting shaft. The first driving motor drives the first driving wheel to rotate through the first transmission connecting shaft. The rotation speed of the first driving motor directly determines the rotation speed of the first driving wheel and the main movement speed of the crawler assembly.

5. The drive structure of the crawler of a stretcher crawler vehicle according to claim 4, characterized in that, The second driving motor is fixedly installed inside the right side of the rear end of the frame body. The second driving motor is a DC brushless motor with the same specification as the first driving motor. The output shaft of the second driving motor is connected to the shaft hole of the second driving wheel through a second transmission connecting shaft. The difference between the rotation speed of the second driving motor and the rotation speed of the first driving motor is used to adjust the tension state of the crawler assembly.

6. The drive structure of the crawler of a stretcher crawler vehicle according to claim 5, characterized in that, The first support wheel is made of high-strength aluminum alloy material and is in a circular disc structure. The outer peripheral surface of the first support wheel is smooth without tooth grooves. The outer peripheral surface of the first support wheel is in smooth contact with the inner side of the crawler assembly, and is used to support the front part of the crawler assembly and guide the crawler assembly to move along a predetermined path.

7. The drive structure of the crawler of a stretcher crawler vehicle according to claim 6, characterized in that, The second support wheel is made of the same high-strength aluminum alloy material as the first support wheel and has a circular disc structure. The outer peripheral surface of the second support wheel is smooth without tooth grooves, and the outer peripheral surface of the second support wheel is in smooth contact with the inner side of the crawler assembly, which is used to support the rear part of the crawler assembly and maintain an appropriate tension state of the crawler assembly.

8. The drive structure of the crawler of a stretcher crawler vehicle according to claim 7, characterized in that, The crawler assembly is made by compounding high-strength rubber material and steel cord, and has a continuous annular belt structure. The inner side of the crawler assembly is provided with a rack structure matching the tooth grooves of the first drive wheel and the second drive wheel, and the outer side of the crawler assembly is provided with anti-slip patterns. The crawler assembly is arranged around the first drive wheel, the second drive wheel, the first support wheel and the second support wheel.

9. The drive structure of the crawler of a stretcher crawler vehicle according to claim 8, characterized in that, The tension adjustment mechanism includes a tension detection device and a speed adjustment device. The tension detection device is arranged above the crawler assembly between the first support wheel and the second support wheel. The tension detection device includes a pressure sensing rod and an elastic reset element. One end of the pressure sensing rod is in contact with the outer surface of the crawler assembly, and the other end is connected to the elastic reset element. When the tension of the crawler assembly increases, the downward movement distance of the pressure sensing rod increases, and the compression amount of the elastic reset element increases accordingly.

10. The drive structure of the crawler of a stretcher crawler vehicle according to claim 9, characterized in that, The speed adjustment device includes a mechanical governor and a transmission gear set. The mechanical governor works based on the centrifugal speed regulation principle. There are two symmetrically distributed centrifugal blocks inside the mechanical governor. The centrifugal blocks are connected to the central shaft of the mechanical governor through hinge shafts. When the speed of the mechanical governor changes, the centrifugal force of the centrifugal blocks changes accordingly. The position change of the centrifugal blocks drives the adjustment rod to move, and the movement of the adjustment rod changes the transmission ratio of the transmission gear set.

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