Unmanned formula car steering system

Abstract

The invention belongs to the field of unmanned driving, and particularly relates to an unmanned formula car steering system. An unmanned formula car steering system comprises a steering wheel, a transmission mechanism, a steering mechanism and a power device. And the other end of the transmission mechanism is connected with the steering mechanism. The power device is connected with the steering mechanism and used for providing power for the steering mechanism during unmanned driving. The rack is provided with a first tooth and a second tooth, the transmission mechanism is provided with a first gear, the power device is provided with a second gear, the first gear is meshed with the first tooth, and the second gear is meshed with the second tooth. The power device is directly connected with the gear II, so that an additional connecting mechanism is not needed for connecting the power device and the rack, the structural composition of the whole steering system is greatly simplified, the structure of the whole steering system is smaller and smaller, the occupied space is small, and normal driving operation of a driver cannot be interfered.

Description

Technical Field

[0001] The invention belongs to the technical field of formula racing cars, and in particular relates to a steering system for an unmanned formula racing car. Background Art

[0002] Racing originated in 1894. At that time, there were no restrictions on participating vehicles. It was not until the establishment of the International Automobile Federation in 1904 that attempts were made to classify and restrict participating vehicles for fairness and safety reasons. Early classifications were tried from various angles, including maximum vehicle weight, fuel consumption rate, cylinder radius, etc., but the results were not ideal. It was not until the introduction of the concept of cylinder capacity that satisfactory results were achieved. This is the meaning of "formula", a restriction standard for all participating vehicles. Simply put, it is produced according to an equation (not a mathematical equation), so the produced car can be called a formula car.

[0003] In order to promote the cultivation of talents in our automotive industry, the China University Student Unmanned Driving Formula Competition will be held. In this competition, college students modify the original racing cars to study the unmanned driving racing technology. The competition requires unmanned driving to be achieved in the technology that the driver can drive. Among them, the steering system occupies a relatively important position in the entire formula racing development process. Compared with passenger cars, the racing chassis has a more extreme working environment, more bends, and fast cornering speeds. This puts higher requirements on the steering system of the racing car. In addition to the basic design requirements such as reliable structure and relatively light steering, it is more important that the steering system has sufficient stability. At present, the steering system in the formula racing car is generally C-EPS, the full name is Column-EPS, that is, the motor acting on the steering column. The motor is generally suspended behind the steering wheel. If this steering system is used, the motor will interfere with the driver's knees, thereby affecting the driver's normal operation when driving the racing car. In addition, the center of gravity of the motor in the existing steering system is high, which makes the center of gravity of the entire racing car move upward, which is not conducive to the stability of the driver during driving. In addition, when the existing steering system connects the motor suspended behind the steering wheel to the steering column, an intermediate mechanism is required to connect the two, which makes the structure of the entire steering mechanism complex and occupies a large space. In the narrow space of a racing car, it will interfere with the driver's operation while driving. Summary of the invention

[0004] In order to solve the technical problem that the steering system of the existing racing car is difficult to enhance the stability of the racing car while reducing the interference to the driver during normal driving, the present invention provides a steering system for an unmanned formula racing car.

[0005] The present invention is implemented by the following technical scheme: a steering system of an unmanned formula racing car, comprising: a steering wheel, a transmission mechanism, a steering mechanism and a power device, one end of the transmission mechanism is connected to the steering wheel, the other end of the transmission mechanism is connected to the steering mechanism, the steering wheel is used to provide steering power to the steering mechanism through the transmission mechanism when the unmanned formula racing car is manned; the power device is installed on one side of the transmission mechanism, the power device is connected to the steering mechanism, and the power device is used to provide power to the steering mechanism when the unmanned formula racing car is unmanned;

[0006] The steering mechanism includes a rack and at least one rack limiting device, the rack is inserted into the rack limiting device along its axial direction, and the rack limiting device is used to limit the radial movement of the rack; the rack is provided with a tooth 1 and a tooth 2, in the axial direction of the rack, the tooth 2 is arranged on one side of the tooth 1; in the radial direction of the rack, the tooth 2 is arranged horizontally, the tooth 1 is arranged downwardly from the bottom of the tooth 2 and the tooth 1 faces the transmission mechanism, and the angle between the tooth 1 and the horizontal plane where the tooth 2 is located is 110°; the transmission mechanism includes a gear 1 meshing with the tooth 1, and the rotation of the steering wheel is converted into the axial movement of the rack through the mutual meshing of the gear 1 and the tooth 1; the power device includes a gear 2 meshing with the tooth 2, the gear 2 is horizontally arranged above the tooth 2, and the power of the power device is converted into the axial movement of the rack through the mutual meshing of the gear 2 and the tooth 2.

[0007] As a further improvement of the present invention, the power device further includes a motor, a worm gear reducer and a clutch, the input end of the worm gear reducer is connected to the motor, one end of the clutch is connected to the output end of the worm gear reducer, and the other end of the clutch is connected to the gear 2, and the connection and separation between the worm gear reducer and the gear 2 are achieved through the clutch. When the unmanned formula car is in the unmanned driving mode, the clutch is in an engaged state, and the clutch is respectively connected to the worm gear reducer and the gear 2; when the unmanned formula car is in the manned driving mode, the clutch is in a disengaged state, and the worm gear reducer and the gear 2 are disconnected;

[0008] The axis of the clutch and the axis of the output end of the worm gear reducer are both on the central axis of gear two, and the axis of the motor is on the straight line where the axis of the input end of the worm gear reducer is located; in the axial direction of gear two, the input end is located below the output end, the straight line where the axis of the motor is located and the straight line where the axis of the clutch is located are perpendicular to each other, and the clutch, the worm gear reducer and the motor form an L-shaped structure.

[0009] As a further improvement of the present invention, the gear 2 is located in the length direction of the rack, and the distance from the gear 2 to the center line in the length direction ranges from one third to two fifths of the distance from the end of one side of the rack to the center line.

[0010] As a further improvement of the present invention, the transmission mechanism also includes a quick-release assembly, a transmission shaft and a shell one, one end of the quick-release assembly is fixedly connected to the steering wheel, both ends of the transmission shaft are provided with universal joints, one end of the transmission shaft is connected to an end of the quick-release assembly away from the steering wheel through the universal joint; the shell one is mounted on the rack, the gear one is mounted in the shell one, and the other end of the transmission shaft is connected to the gear one through the universal joint.

[0011] As a further improvement of the present invention, the transmission ratio of the worm gear reducer is greater than or equal to 25.

[0012] As a further improvement of the present invention, the maximum turning angle of the outer wheel of the unmanned formula racing car is α max , Wherein, L is the wheelbase between the outer wheel and the inner wheel of the unmanned formula racing car, c is the kingpin offset distance of the unmanned formula racing car, R min is the minimum turning radius of the driverless formula car.

[0013] As a further improvement of the present invention, the angular transmission ratio i of the steering system of the unmanned formula racing car is w is 5:1; the maximum turning angle of the steering wheel is β max , β max =α max* i w ;

[0014] The stroke of the rack is L 1 , Among them, β max is the maximum turning angle of the steering wheel, m is the module of gear one, and z is the number of teeth of gear one.

[0015] As a further improvement of the present invention, the quick-release assembly includes a quick-release device, a quick-release shaft and a quick-release shaft fixing device, one end of the quick-release device is connected to the steering wheel, the other end of the quick-release device is connected to the quick-release shaft, the quick-release shaft fixing device is installed on the quick-release shaft and is used to limit and fix the quick-release shaft, and the other end of the quick-release shaft is connected to the transmission shaft through the universal joint.

[0016] As a further improvement of the present invention, the clutch is an electromagnetic clutch.

[0017] As a further improvement of the present invention, the gear 1 and the gear 2 are two completely identical spur gears.

[0018] As a further improvement of the present invention, the number of teeth of gear one is 17, the module of gear one is 1.5, the pressure angle of gear one is 20°, and the helix angle of gear one is 0°.

[0019] The technical solution provided by the present invention has the following beneficial effects:

[0020] (1) The present invention connects the power device directly to the second gear, so that no additional connecting mechanism is required to connect the power device and the rack, thereby greatly simplifying the structural composition of the entire steering system, making the structure of the entire steering system more compact, occupying less space, and not interfering with the driver's normal driving operation.

[0021] (2) The present invention arranges the second tooth in the horizontal direction. The purpose of the horizontal arrangement is that the second gear, the clutch, the worm gear reducer and the motor connected thereto can be arranged horizontally with the bottom of the racing car, so that they are located in the space below the driver's legs, thereby improving the space utilization rate and making the design of the entire steering system more reasonable. At the same time, the present invention arranges the angle between the first tooth and the second tooth in the horizontal plane to be 110°, so that the angle of the universal joint is reduced from the existing 35° to about 25°, thereby reducing the speed unevenness coefficient of the universal joint from 0.4016 to 0.1969, thereby enhancing the stability of the racing car. Therefore, the steering system of the present invention can maintain the stability of the racing car while arranging the power device at the bottom of the racing car, so that the power device is located in the space below the driver's legs, thereby reducing the interference caused by the power device to the driver when driving.

[0022] (3) The present invention increases the space of the front cabin of the racing car by designing a worm gear reducer and utilizing its high transmission ratio and small size. The motor is placed in the middle of the bottom of the front cabin by perfectly utilizing the change of its transmission direction, and the position of the motor is lowered by utilizing the center distance, which makes it easier to fix and lowers its center, so that the power unit is located in the space under the driver's legs, thereby improving its space utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A stereoscopic diagram of a steering system for an unmanned formula racing car provided by the present invention.

[0024] Figure 2 It is a schematic diagram of the power device of the present invention when the various components are separated.

[0025] Figure 3 It is an enlarged structural schematic diagram of the steering mechanism in the present invention.

[0026] Figure 4 It is a structural schematic diagram of the angle between tooth one and tooth two in the present invention.

[0027] Figure 5 It is a partial structural enlarged schematic diagram of the steering system of the driverless formula racing car in the present invention.

[0028] Figure 6 It is a front view of the steering system of the unmanned formula racing car in the present invention.

[0029] Figure 7 The figure is a top view of the steering system of the driverless formula racing car in the present invention.

[0030] The markings in the figure are: 1. steering wheel; 21. quick release; 22. quick release shaft fixing device; 23. quick release shaft; 24. universal joint; 25. gear one; 26. transmission shaft; 27. housing one; 31. rack; 311. gear one; 312. gear two; 313. rack joint; 32. rack limit device; 41. gear two; 42. motor; 43. worm gear reducer; 431. input end; 432. output end; 44. clutch. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0032] In the description of the present invention, it should be noted that for directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions and positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific protection scope of the present invention. The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. The terms "including" and "having" in the specification and claims of the present invention and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device including a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] A steering system for an unmanned formula racing car, such as Figure 1 As shown, it includes a steering wheel 1, a transmission mechanism, a steering mechanism and a power device. One end of the transmission mechanism is connected to the steering wheel 1, and the other end of the transmission mechanism is connected to the steering mechanism, so that the steering wheel 1 can provide steering power to the steering mechanism through the transmission mechanism. The power device is installed on one side of the transmission mechanism, and the power device is connected to the steering mechanism. The power device is used to provide power to the steering mechanism when no one is driving.

[0034] Please refer to Figure 1 and Figure 2 , the transmission mechanism includes a quick-release assembly, a transmission shaft 26, a gear 25 and a housing 27. One end of the quick-release assembly is fixedly connected to the steering wheel 1, and both ends of the transmission shaft 26 are provided with a universal joint 24. One end of the transmission shaft 26 is connected to the end of the quick-release assembly away from the steering wheel 1 through the universal joint 24, and the other end of the transmission shaft 26 is connected to the gear 25 through the universal joint 24. The steering wheel 1 and the transmission mechanism are used when someone is driving. The driver can turn the steering wheel 1, and the steering wheel 1 transmits power to the steering mechanism through the quick-release assembly, the transmission shaft 26 and the gear 25 in turn, so that the steering mechanism can achieve the purpose of steering. It can be understood that the provision of a quick-release assembly can realize the rapid removal of the steering wheel 1 from the transmission shaft 26, which is convenient for later maintenance or replacement.

[0035] It is understandable that the universal joint 24 can be a cross-axis universal joint 24. The cross-axis universal joint 24 has a large angle compensation capability, a compact and reasonable structure, high transmission efficiency, and increases its flexibility during installation and use.

[0036] For further information, please refer to Figure 2 and Figure 3 The steering mechanism includes a rack 31 and at least one rack limiting device 32. The rack 31 is inserted into the rack limiting device 32 along its axial direction. The rack limiting device 32 is used to limit the movement of the rack 31 in the radial direction. The rack 31 is provided with a tooth 1 311 and a tooth 2 312. The tooth 2 312 is arranged on one side of the tooth 1 311. In the axial direction of the rack 31, the tooth 2 312 is arranged on one side of the tooth 1 311, and the tooth 2 312 is on the same side as the power device, so that the power device can be directly connected to the tooth 2 312, so that it does not need an additional connecting mechanism to connect the power device and the rack 31, which greatly simplifies the structural composition of the entire steering system, making the structure of the entire steering system more compact, occupying less space, and will not interfere with the normal driving operation of the driver. In the radial direction of the rack 31, the tooth 2 312 is arranged in the horizontal direction. The purpose of the horizontal arrangement is to allow the gear 2 41, clutch 44, worm gear reducer 43 and motor 42 connected thereto to be arranged horizontally with the bottom of the racing car, so that they are located in the space below the driver's legs, thereby improving the space utilization and making the design of the entire steering system more reasonable. The tooth 1 311 is arranged obliquely from the lower left side of the tooth 2 312, and the tooth 1 311 faces the gear 1 25. It can be understood that, please refer to Figure 3 and Figure 4 ,in Figure 4 The middle X axis can be the horizontal plane where the tooth 2 312 is located, and the Y axis is the straight line where the tooth 1 311 is located. The angle between the straight line where the tooth 1 311 is located and the horizontal plane where the tooth 2 312 is located is 110°, that is, the angle between the straight line where the tooth 1 311 is located and the vertical plane is 20°. By setting the tooth 1 311 to have an inclination angle of 20° with the vertical plane, the angle of the universal joint 24 can be reduced from about 35° to about 25°, thereby reducing the torque fluctuation when turning through the steering wheel 1 and the transmission mechanism, enhancing the stability of the transmission shaft 2626 when the racing car is turning, reducing the shaking of the gear 1 25, thereby reducing the impact on the gear 1 25 when turning, and extending the service life of the gear 1 25. The angle of the universal joint 24 here is the angle between the central axis of the universal joint 24 and the central axis of the transmission shaft 26.

[0037] The rotational non-uniformity coefficient of the universal joint 24 is k, k=sinθtanθ, wherein θ is the angle of the universal joint 24 .

[0038] In this embodiment, there are two universal joints 24, which are named as universal joint 1 and universal joint 2 below. One end of universal joint 1 is connected to the steering wheel 1, and the other end of universal joint 1 is connected to one end of the transmission shaft 26. One end of universal joint 2 is connected to the other end of the transmission shaft 26, and the other end of universal joint 2 is connected to the gear. The angle of universal joint 1 is the angle between the central axis of universal joint 1 and the central axis of the transmission shaft 26. The angle of universal joint 2 is the angle between the central axis of universal joint 2 and the central axis of the transmission shaft 26. In the actual design process, in order to make the output shaft speed of universal joint 2 equal to the input shaft speed of universal joint 1 while changing the transmission direction, the angle of universal joint 1 and the angle of universal joint 2 are set to the same angle. Therefore, in this embodiment, the rotation unevenness coefficient of universal joint 1 is the same as the rotation unevenness coefficient of universal joint 2.

[0039] The angle of the universal joint 24 of the existing steering system is generally 35°, and the rotation unevenness coefficient of the universal joint 24 of the existing steering system is k 1 .

[0040] k 1 =sin35°tan35°≈0.5736×0.7=0.4016;

[0041] In this embodiment, the angle of the universal joint 24 in the steering system is 25°, and the rotation unevenness coefficient of the universal joint 24 in the steering system in this embodiment is k 2 .

[0042] k 2 =sin25°tan25°≈0.4226×0.466=0.1969;

[0043] It can be seen from the above data that the embodiment adjusts the inclination angle of tooth 1 311 so that the angle of universal joint 24 is reduced from the existing 35° to about 25°, thereby reducing the speed unevenness coefficient of universal joint 24 from 0.4016 to 0.1969, which is reduced by about 50%. By reducing the speed unevenness coefficient of universal joint 24, a universal joint 24 that is shorter than the prior art for connecting gear 1 25 can be selected, thereby reducing the lateral torque of gear 1 25 during the steering process, thereby reducing the shaking of gear 1 25 and extending the life of the gear. At the same time, the steering system assembled by this embodiment is installed on a racing car for testing, and it is found that the free range of the racing car after applying the steering system of the present invention is reduced from 6.2 degrees to 3.5 degrees. The reduction in free range can speed up the response speed of the steering system and improve its steering speed.

[0044] In the actual design process, a groove can be designed on the gear 1 25, through which it can be directly connected to the universal joint 24, so that there will be no relative rotation between the universal joint 24 and the gear 1 25, thereby improving the stability of the universal joint 24 when driving the gear 1 25 to rotate.

[0045] In this embodiment, there are two rack limit devices 32, and the two rack limit devices 32 are symmetrically distributed along the axial direction of the rack 31. The rack limit device 32 includes a mounting seat and a sliding bearing, the sliding bearing is sleeved on the outer side of the rack 31, and there can be an interference fit between the sliding bearing and the mounting seat, which can limit the four degrees of freedom of the rack 31 except axial displacement and rotation. The mounting seat is also provided with a mounting hole, through which the mounting seat can be fixed on the racing car.

[0046] Please refer to Figure 3 Rack 31 joints are also provided at both ends of the rack 31. The rack 31 joints are located at the ends of the rack 31 and are used to connect with other components.

[0047] Please refer to Figures 2 to 5 The power device includes a gear 2 41, a motor 42, a worm gear reducer 43 and a clutch 44. The gear 2 41 is horizontally arranged above the rack 31 and meshes with the gear 2 312. One end of the clutch 44 is connected to the gear 2 41, and the other end of the clutch 44 is connected to the output end 432 of the worm gear reducer 43. The motor 42 is connected to the input end 431 of the worm gear reducer 43, and the motor 42 is able to transmit power to the gear 2 41 through the worm gear reducer 43 and the clutch 44. The gear 2 41 is meshed with the gear 2 312 to drive the rack 31 to move in its axial direction. In this embodiment, the connection and separation between the worm gear reducer 43 and the gear 2 41 are realized by setting the clutch 44. When the driverless formula car is in the driverless mode, the clutch 44 is in the engaged state, and the clutch 44 is respectively connected to the worm gear reducer 43 and the gear 2 41. At this time, the motor 42 is started, the motor 42 can provide torque, which is then increased by the worm gear reducer 43, and then transmitted to the gear 2 41 through the clutch 44. The gear 2 41 and the gear 2 312 are meshed with each other to drive the rack 31 to move, so as to realize the steering of the unmanned formula car in the unmanned driving mode.

[0048] In this embodiment, the rotation of the rack 31 itself is limited by the meshing of the gear 2 41 with the tooth 2 312 and the meshing of the gear 1 25 with the tooth 1 311 .

[0049] In this embodiment, a key transmission connection can be used between the worm gear reducer 43 and the clutch 44. The advantage of using a key transmission connection is that it is convenient to disassemble the worm gear reducer 43 and the clutch 44. Compared with spline and bolt connections, ordinary flat key connections can be directly matched, so that no special tools are required during installation. In this embodiment, the structural strength between the worm gear reducer 43 and the clutch 44 connected by key transmission is also simulated and analyzed. The conclusion obtained by the analysis is that when a key transmission connection is used, the force at the key connection is not large, and its connection strength meets the use requirements. Therefore, a key transmission connection can be used between the worm gear reducer 43 and the clutch 44.

[0050] During installation, please refer to Figure 7 Gear 2 41 is located in the length direction of the rack 31, and the distance from gear 2 41 to the center line of the length direction of the rack 31 is one third to two fifths of the distance from the end of one side of the rack 31 to the center line, so that the entire rack 31 can operate normally.

[0051] In this embodiment, the distance between the second gear 41 and the center line of the rack 31 in the length direction may range from 65 mm to 70 mm.

[0052] It can be understood that in this embodiment, the clutch 44 can be an electromagnetic clutch 44, and the connection between the clutch 44 and the gear 2 41 and the worm gear reducer 43 is achieved by energizing the electromagnetic clutch 44, and the disconnection between the clutch 44 and the gear 2 41 and the worm gear reducer 43 is achieved by de-energizing the electromagnetic clutch 44.

[0053] Gear 1 25 and gear 2 41 can be two identical spur gears.

[0054] The number of teeth of gear 1 25 may be 17, the module of gear 1 25 may be 1.5, the pressure angle of gear 1 25 may be 20°, and the helix angle of gear 1 25 may be 0°.

[0055] When the driverless formula car is in a manned state, the electromagnetic clutch 44 is powered off, and the gear 2 41 and the electromagnetic clutch 44 are disconnected. The steering wheel 1 is manually turned to apply torque, and the gear 1 25 is driven to rotate through the transmission shaft 26 and the universal joint 24. When the gear 1 25 is meshed with the gear 1 311, the rack 31 is driven to move along the axial direction of the rack 31, and the rack 31 is able to pull the tie rod on the car connected to it, and then the wheel is rotated around the main axis through the steering knuckle arm, thereby realizing the steering of the driverless formula car in the manned driving mode. Among them, it can be understood that how the rack 31 drives the wheel to rotate around the main axis through the tie rod and the steering knuckle arm is a prior art, so it is not described in detail in this embodiment.

[0056] In this embodiment, the axis of the clutch 44 and the axis of the output end 432 of the worm gear reducer 43 are both on the central axis of the gear 2 41. The axis of the motor 42 is on the straight line where the axis of the input end 431 of the worm gear reducer 43 is located. In the axial direction of the gear 2 41, the input end 431 is located below the output end 432. In this embodiment, the input end 431 is located about 30 mm below the output end 432. In this way, while the power device is directly connected to the rack 31, the input end 431 of the worm gear reducer 43 is located below the output end 432, which can effectively lower the center of gravity of the motor 42 and better fix the motor 42 on the racing car.

[0057] In this embodiment, the worm gear reducer 43 has a high transmission ratio. If other reducers, such as bevel gear reducers, are selected, the transmission ratio is small. In the actual assembly process, multi-stage bevel gears are required to increase the transmission ratio. The structure of the multi-stage bevel gears will make the entire steering system complex and occupy a large space. Therefore, under the condition of the same transmission ratio, the worm gear reducer 43 is smaller in size than other reducers and is more suitable for use in racing cars.

[0058] The present invention increases the space of the front cabin of the racing car by designing a worm gear reducer and utilizing its high transmission ratio and small size. The motor 42 is perfectly placed in the middle of the bottom of the front cabin by utilizing the change of its transmission direction, and the position of the motor 42 is lowered by utilizing the center distance, so that the power unit is located in the space below the driver's legs, thereby improving its space utilization.

[0059] In this embodiment, the transmission ratio of the worm gear reducer 43 is greater than or equal to 25.

[0060] In this embodiment, please refer to Figure 5 and Figure 6 The straight line where the axis of the motor 42 is located and the straight line where the axis of the clutch 44 is located are perpendicular to each other, so that the clutch 44, the worm gear reducer 43 and the motor 42 form an L-shaped structure. In actual operation, since the center of gravity of the motor 42 is lowered, it is convenient to fix the motor 42 and the entire power device is an L-shaped structure, which can make good use of the space under the driver's legs and improve the utilization rate of the space. At the same time, the power device is small enough and will not interfere with the normal operation of the driver during driving, making the design of the entire steering system more ingenious and reasonable.

[0061] It is understandable that in the prior art, the steering wheel hand torque M in the unmanned formula car steering system is hIt is about 20.35N·m. The specific calculation process can be referred to the following paragraphs. Although the transmission efficiency of the worm gear reducer 43 is not high, its output torque is at least 22.2N·m, which is greater than the steering wheel torque M of the unmanned formula car steering system. h , because it can be proved that the worm gear reducer 43 in this embodiment meets the steering requirements.

[0062] The housing 27 is sleeved on the rack 31. In the actual installation process, the housing 27 can be fixed on the racing car by bolts, the gear 25 is installed in the housing 27, and the gear 25 can rotate in the housing 27, and the universal joint 24 on the transmission shaft 26 close to the gear 25 extends into the housing 27 and is connected with the gear 25. In the actual operation process, if the unmanned formula racing car is in a manned state, the power unit and the rack 31 are disconnected at this time, and the driver can apply torque by turning the steering wheel 1, and then the axial movement of the rack 31 is driven by the mutual engagement of the quick release assembly, the transmission shaft 26, the gear 25 and the gear 311 in turn, so that the rack 31 can drive the tie rod on the unmanned formula racing car, and then the wheel is rotated around the main axis through the steering knuckle arm, thereby achieving the purpose of steering.

[0063] Please refer to Figure 6 The quick release assembly includes a quick release device 21, a quick release shaft 23 and a quick release shaft 23 fixing device 22. One end of the quick release device 21 is connected to the steering wheel 1, the other end of the quick release device 21 is connected to one end of the quick release shaft 23, the other end of the quick release shaft 23 is connected to the transmission shaft 26 through a universal joint 24, and the quick release shaft 23 fixing device 22 is sleeved on the outside of the quick release shaft 23. The quick release shaft 23 fixing device 22 is used to limit the quick release shaft 23, so that the quick release shaft 23 can only rotate along its axial direction, but cannot move along its axial direction. Therefore, the steering wheel 1 can control the transmission shaft 26 to be twisted through the quick release assembly, and the transmission shaft 26 can drive the gear 1 25 to rotate. Through the mutual engagement of the gear 1 25 and the gear 1 311, the rotation of the steering wheel 1 is converted into the axial movement of the rack 31, and then the rack 31 acts on the tie rod on the driverless formula car, and finally the steering knuckle arm is used to make the wheels of the car rotate around the main axis, thereby achieving the purpose of steering.

[0064] In actual competition, the competition rules require that the minimum turning radius of the track is 9 meters. At the same time, the situation that the car may return to the track after leaving the track during the competition is taken into consideration, and according to the actual situation of the track and the feedback data of the steering system of the car in the previous competition, and taking into account the possible understeering situation, the minimum turning radius of the car is designed to be 3.5 meters in this embodiment.

[0065] It can be understood that, in this embodiment, the angular transmission ratio i of the steering system of the driverless formula racing car is w It can be 5:1.

[0066] It can be understood that, in this embodiment, the maximum turning angle of the outer wheel of the driverless formula car is α max ;

[0067] Among them, L is the wheelbase between the outer wheel and the inner wheel of the driverless formula car, and its value is 1580mm; c is the kingpin offset of the driverless formula car, and its value is 30mm; R min The minimum turning radius of an unmanned formula car is 3500mm.

[0068] Right now

[0069] From this we can see that α max =27°, that is, the maximum turning angle of the outer wheel is 27°. According to the angular transmission ratio i of the steering system of the driverless formula car w is 5:1, and β is defined max is the maximum turning angle of steering wheel 1, that is We can get β max At this turning angle, the unmanned formula car can be steered well through the steering wheel 1 without the problem of crossing the hands, thereby improving the convenience and smoothness of steering through the steering wheel 1 in the manned driving mode.

[0070] Define the travel of rack 31 as L 1 m is defined as the module of gear 25, which can be selected as 1.5. z is defined as the number of teeth of gear 25, which can be selected as 17. The pressure angle of gear 25 can be selected as 20°, and the helix angle of gear 25 can be selected as 0°.

[0071] According to the formula Among them, β max is the maximum turning angle of the steering wheel 1, m is the module of gear 25, and z is the number of teeth of gear 25.

[0072] Right now

[0073] The stroke of the rack 31 may be 60 mm.

[0074] Among them, in this scheme, the steering wheel 1 hand torque M h The determination process is as follows: Under normal circumstances, the in-situ steering resistance torque of the vehicle is the largest, and as the vehicle speed increases, the steering resistance torque decreases. In this embodiment, the in-situ steering resistance torque M of the driverless formula car can be calculated first. R, and then through the in-situ steering resistance torque M R To calculate the steering wheel torque M of the driverless formula car h .

[0075] In this embodiment, the calculation formula of the steering wheel hand torque of the driverless formula car is as follows:

[0076]

[0077] Among them, M R is the stationary steering resistance torque of the driverless formula car, and its unit is N·m; L d1 is the steering rocker arm length, in mm; L d2 is the length of the steering knuckle arm, in mm; L d1 / L d2 The value of is generally between 0.85 and 1.1, and can be approximately 1 in this embodiment. w is the angular transmission ratio of the steering system, and its value is 5:1. SG is the steering efficiency of the steering system, and its value is 90%.

[0078] The stationary steering resistance torque M of the driverless formula car is R The calculation of is as follows:

[0079] Where f is the sliding friction coefficient between the wheel and the ground, which is generally 0.7; G 1 is the vertical load of the steering wheel, its unit is N, and p is the inflation pressure of the wheel tire, which is generally 0.08MPa.

[0080] Among them, G 1 =M 车 ×K a ×g,M 车 is the vehicle mass, which is 330kg; K a is the load distribution coefficient, which means that 43% of the vehicle's mass is distributed to the front wheels, and its value is 0.43; g is the acceleration of gravity, and its value is 9.8.

[0081] Calculate G 1 =M 车 ×K a ×g=330*0.43*9.8=1455.3N;

[0082] From this we get

[0083] The in-situ steering resistance torque M of the driverless formula car R , calculate M h ;

[0084]

[0085] In addition, in this embodiment, the steering wheel of the unmanned formula car can also be used to exert a hand torque M h To calculate the steering wheel 1 hand force F h , Among them, D sw is the steering wheel diameter, and its value is 240mm.

[0086] Right now

[0087] In this embodiment, the minimum torque output by the selected worm gear reducer 43 is 22.2 N·m, and the steering wheel torque M1 obtained by calculation is h The output torque of the worm gear reducer 43 is greater than the steering wheel 1-hand torque of the unmanned racing car steering coefficient, so it can be proved that the worm gear reducer 43 selected in this embodiment can meet the steering requirements.

[0088] By calculating the steering wheel 1 hand force F h , its value is 84.79N. By consulting the literature, we know that the maximum steering force F required by the national standard GB176754.1.1 is a For less than or equal to 150N, F h The value is less than F a , it means that the steering system of this embodiment meets the actual requirements.

[0089] In this solution, the rated power of the motor 42 selected is 220W, and the rated output torque is 1.27±10%N·m. The minimum transmission ratio required by the motor 42 is set to i.

[0090] Among them, M h is the steering wheel 1 hand torque, its value is 20.35N·m; M 1 is the rated output torque of the motor 42, and its value is 1.27 N·m; η is the transmission efficiency of the motor 42, and its value is 70%.

[0091] Right now

[0092] Therefore, we select a worm gear reducer 43 with a transmission ratio greater than or equal to 25, which is greater than the minimum transmission ratio required by the motor 42 and meets the design requirements.

[0093] It can be understood that the total output torque M of the worm gear reducer 43 with a transmission ratio of 25 is M=M 1 ×η×i a ; Among them, M1 is the rated output torque of the motor 42, and its value is 1.27 N·m; η is the transmission efficiency of the motor 42, and its value is 70%; i a is the transmission ratio of the worm gear reducer 43, and its value is 25.

[0094] That is, M = 1.27 × 70% × 25 = 22.23 N m, and the steering wheel 1 hand torque M h The value is 20.35 N·m. That is, the value of the total output torque M of the worm gear reducer 43 is greater than the steering wheel 1 hand torque M h This proves that the steering system designed in this embodiment is feasible.

[0095] The above describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. An unmanned formula racing car steering system, characterized in that: The invention comprises: a steering wheel (1), a transmission mechanism, a steering mechanism and a power device, wherein one end of the transmission mechanism is connected to the steering wheel (1), and the other end of the transmission mechanism is connected to the steering mechanism, and the steering wheel (1) is used to provide steering power to the steering mechanism through the transmission mechanism when the unmanned formula racing car is manned; the power device is installed on one side of the transmission mechanism, and the power device is connected to the steering mechanism, and the power device is used to provide power to the steering mechanism when the unmanned formula racing car is unmanned; The steering mechanism comprises a rack (31) and at least one rack limiting device (32), wherein the rack (31) is inserted into the rack limiting device (32) along its axial direction, and the rack limiting device (32) is used to limit the movement of the rack (31) in the radial direction; the rack (31) is provided with a first tooth (311) and a second tooth (312), wherein in the axial direction of the rack (31), the second tooth (312) is arranged on one side of the first tooth (311); in the radial direction of the rack (31), the second tooth (312) is arranged horizontally, and the first tooth (311) is arranged to be inclined downward from below the second tooth (312) and the first tooth (311) faces the The transmission mechanism comprises a gear 1 (25) meshing with the gear 1 (311) and a horizontal plane where the gear 2 (312) is located, and the angle between the horizontal planes where the gear 1 (311) and the gear 2 (312) are located is 110°; the transmission mechanism comprises a gear 1 (25) meshing with the gear 1 (311), and the rotation of the steering wheel (1) is converted into the axial movement of the rack (31) through the mutual meshing of the gear 1 (25) and the gear 1 (311); the power device comprises a gear 2 (41) meshing with the gear 2 (312), and the gear 2 (41) is horizontally arranged above the gear 2 (312), and the power of the power device is converted into the axial movement of the rack (31) through the mutual meshing of the gear 2 (41) and the gear 2 (312).

2. The unmanned formula racing car steering system according to claim 1, characterized in that: The power device further comprises a motor (42), a worm gear reducer (43) and a clutch (44); an input end (431) of the worm gear reducer (43) is connected to the motor (42); one end of the clutch (44) is connected to an output end (432) of the worm gear reducer (43); the other end of the clutch (44) is connected to the gear 2 (41); the worm gear reducer (43) and the gear 2 (41) are connected and separated by the clutch (44); when the unmanned formula car is in an unmanned driving mode, the clutch (44) is in an engaged state, and the clutch (44) is respectively connected to the worm gear reducer (43) and the gear 2 (41); when the unmanned formula car is in a manned driving mode, the clutch (44) is in a disengaged state, and the worm gear reducer (43) and the gear 2 (41) are disconnected; The axis of the clutch (44) and the axis of the output end (432) of the worm gear reducer (43) are both on the central axis of the gear two (41), and the axis of the motor (42) is on the straight line where the axis of the input end (431) of the worm gear reducer (43) is located; in the axial direction of the gear two (41), the input end (431) is located below the output end (432), the straight line where the axis of the motor (42) is located and the straight line where the axis of the clutch (44) is located are perpendicular to each other, and the clutch (44), the worm gear reducer (43) and the motor (42) form an L-shaped structure.

3. The unmanned driving formula racing car steering system as claimed in claim 1, characterized in that: The second gear (41) is located in the length direction of the rack (31), and the distance between the second gear (41) and the center line in the length direction is one third to two fifths of the distance from the end of one side of the rack (31) to the center line.

4. The unmanned driving formula racing car steering system as claimed in claim 1, characterized in that: The transmission mechanism further comprises a quick-release assembly, a transmission shaft (26) and a housing (27); one end of the quick-release assembly is fixedly connected to the steering wheel (1); both ends of the transmission shaft (26) are provided with universal joints (24); one end of the transmission shaft (26) is connected to an end of the quick-release assembly away from the steering wheel (1) through the universal joint (24); the housing (27) is mounted on the rack (31); the gear (25) is mounted in the housing (27); the other end of the transmission shaft (26) is connected to the gear (25) through the universal joint (24).

5. The unmanned driving formula racing car steering system as claimed in claim 1, characterized in that: The transmission ratio of the worm gear reducer (43) is greater than or equal to 25.

6. The unmanned driving formula racing car steering system as claimed in claim 1, characterized in that: The maximum turning angle of the outer wheel of the driverless formula car is α max , Wherein, L is the wheelbase between the outer wheel and the inner wheel of the unmanned formula racing car, c is the kingpin offset distance of the unmanned formula racing car, R min is the minimum turning radius of the driverless formula car.

7. The unmanned driving formula racing car steering system as claimed in claim 4, characterized in that: The angular transmission ratio i of the steering system of the driverless formula racing car w is 5:1; the maximum turning angle of the steering wheel (1) is β max , β max =α max ×i w ; The stroke of the rack (31) is L1, Among them, β max is the maximum rotation angle of the steering wheel (1), m is the module of the gear one (25), and z is the number of teeth of the gear one (25).

8. The unmanned driving formula racing car steering system as claimed in claim 3, characterized in that: The quick-release assembly comprises a quick-release device (21), a quick-release shaft (23) and a quick-release shaft (23) fixing device (22); one end of the quick-release device (21) is connected to the steering wheel (1); the other end of the quick-release device (21) is connected to the quick-release shaft (23); the quick-release shaft (23) fixing device (22) is mounted on the quick-release shaft (23) and is used to limit and fix the quick-release shaft (23); the other end of the quick-release shaft (23) is connected to the transmission shaft (26) via the universal joint (24).

9. The unmanned driving formula racing car steering system as claimed in claim 3, characterized in that: The universal joint (24) is a cross-axis universal joint (24); And / or, the clutch (44) is an electromagnetic clutch (44).

10. The unmanned driving formula racing car steering system as claimed in claim 1, characterized in that: The gear one (25) and the gear two (41) are two identical spur gears; the number of teeth of the gear one (25) is 17, the module of the gear one (25) is 1.5, the pressure angle of the gear one (25) is 20°, and the helix angle of the gear one (25) is 0°.

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