Method and device for measuring the sliding friction coefficient of a wheel

Abstract

The present application relates to wheel sliding friction coefficient measurement technical field, and disclose a kind of wheel sliding friction coefficient measurement method and device, the left side of base upper end is connected with rotating seat using vertical plate activity, angle measuring assembly is equipped between the left end of rotating seat and vertical plate, drive cylinder body is equipped in the horizontal support of the horizontal support seat of the middle part of base upper end, rotating seat is horizontally supported using horizontal support seat, the output end of drive cylinder body is connected with the right end bottom of rotating seat using sliding link assembly activity;Rotating seat upper end right side is placed with wheel mounting table, and rotating seat right end is equipped with electrically conductive component, and electrically conductive column and electrically conductive component contact to realize the electrification of drive cylinder body.The installation and disassembly of the wheel assembly of the present application are simple, without complex debugging and professional skills.Wheel mounting table can cut off driving power supply in time when sliding on rotating seat, ensure that rotating seat stops at correct angle, further improve angle measuring accuracy, provide strong guarantee for accurate calculation of wheel sliding friction coefficient.

Description

Technical Field

[0001] This invention relates to the field of wheel sliding friction coefficient measurement technology, specifically a method and apparatus for measuring wheel sliding friction coefficient. Background Technology

[0002] In the field of rehabilitation equipment, many devices such as wheelchairs, walking aids, and rehabilitation training carts rely on wheels to achieve mobility. The coefficient of sliding friction of the wheels, as a key performance indicator, has a significant impact on the safety of use, user experience, and rehabilitation effectiveness of rehabilitation equipment.

[0003] Traditional methods for measuring the coefficient of sliding friction of wheels have several drawbacks. Firstly, the wheel to be tested needs to be mounted on the measuring device before measurement and removed afterward, making installation and removal inconvenient and cumbersome. Secondly, when using the inclined plane method (tilted plane method) to measure the coefficient of sliding friction, the tilt angle is gradually increased until the wheel begins to slide, and the friction coefficient is calculated using the critical angle. However, the tilt angle may continue to change as the wheel begins to slide, making it impossible to accurately obtain the critical angle and resulting in inaccurate measurement of the coefficient of sliding friction. Therefore, we have developed a new method and device for measuring the coefficient of sliding friction of wheels. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for measuring the coefficient of sliding friction of a wheel, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A wheel sliding friction coefficient measuring device includes a base, on the upper left side of the base, a rotating seat is movably connected to a vertical plate, and an angle measuring component is provided between the left end of the rotating seat and the vertical plate. The angle measuring component is used to measure the angle between the rotating seat and the horizontal ground.

[0007] The upper middle part of the base is equipped with a drive cylinder. The cross frame is used to horizontally support the rotating seat. The output end of the drive cylinder is movably connected to the bottom right end of the rotating seat by a sliding linkage assembly.

[0008] A wheel mounting platform is placed on the upper right side of the rotating seat. The wheel mounting platform includes a sliding seat, wheel assemblies fixed at both ends of the sliding seat by clamping components, and a conductive post on the right side of the sliding seat. A lifting component is connected between the clamping components. After a counterweight is placed on the lifting component, the clamping component clamps and fixes the wheel assembly.

[0009] The right end of the rotating seat is equipped with a conductive component, and the conductive post contacts the conductive component to realize the power supply to the driving cylinder.

[0010] Preferably, the left end of the rotating seat is movably connected between the upright plates via a rotating shaft;

[0011] The angle measuring component includes a protractor fixed to the side of the upright plate and an angle indicator arrow fixed to the side of the rotating seat by an extension column, the extension column extending through an arc-shaped slot on the protractor.

[0012] Preferably, the upper right side of the base is provided with a sliding groove, and the sliding linkage assembly includes a sliding seat that slides in the sliding groove, a top rod that is movably connected to the upper end of the sliding seat by a connecting ear, and a connecting seat that is movably connected to the outside of the connecting ear.

[0013] The connecting seat is fixedly connected to the piston rod of the drive cylinder. The first pin at the lower end of the push rod passes through the connecting lug and the connecting seat, and the second pin at the upper end of the push rod is movably connected to the vertical lug at the bottom right side of the rotating seat.

[0014] Preferably, the bottom of the slide block is provided with several sets of rollers at equal intervals, and the rollers are supported on the bottom wall of the slide groove.

[0015] The upper right side of the rotating seat is provided with a limiting groove, and long electromagnets are provided on the front and rear side walls of the limiting groove. A baffle is provided on the left end of the limiting groove.

[0016] The bottom of the sliding seat is provided with a protrusion block that extends into the limiting groove. Magnets are provided on the front and rear side walls of the protrusion block, and the magnets and the corresponding long electromagnets repel each other.

[0017] Preferably, the conductive post is fixed to the right end of the protrusion, and the right end of the limiting groove is provided with a through hole;

[0018] The conductive component includes a conductive sheet fixed to the right end of the rotating base and a terminal fixed on the conductive sheet. The terminal is connected to the mains power using a push-button switch.

[0019] The conductive post extends into the through hole and then contacts the corresponding conductive sheet.

[0020] Preferably, the clamping assembly includes a top fixing seat fixed to the left and right ends of the sliding seat, a lower fixing seat movably connected to the sliding seat, and a limiting ball fixed to the side of the lower fixing seat by an L-shaped connecting arm;

[0021] The sliding seat has an opening groove inside, and a protruding plate is provided at the top of the opening groove. The lower fixed seat is movably connected to the protruding plate by a connecting shaft, so that the lower fixed seat is located directly below the corresponding upper fixed seat.

[0022] Preferably, the lifting assembly includes a lifting column extending through and out of the sliding seat, a support plate disposed on the lifting column, a return spring sleeved on the lifting column, and a disc fixed after the bottom of the lifting column extends into the opening slot.

[0023] The reset spring is located at the top of the sliding seat and the bottom of the support plate;

[0024] The limiting ball is engaged in the annular groove on the side of the disk.

[0025] Preferably, the wheel assembly includes a fixed shaft and wheels to be tested sleeved at both ends of the fixed shaft;

[0026] The wheel to be tested is mounted on both ends of a fixed shaft using nuts;

[0027] The fixed shaft is symmetrically provided with limiting annular grooves, and after the lower fixed seat closes with the corresponding top fixed seat upwards, the lower fixed seat and the corresponding top fixed seat are locked in the limiting annular grooves.

[0028] The present invention also provides a method for measuring the coefficient of sliding friction of a wheel, specifically including the following steps:

[0029] S1. The rotating seat is supported on the top of the cross frame to achieve a horizontal setting of the rotating seat. Then, the wheel mounting platform is assembled and placed on the upper right side of the rotating seat so that the conductive column contacts the conductive component to realize the power supply of the drive cylinder.

[0030] S2. Drive the cylinder to work, causing it to rotate the rotating seat through the sliding connecting rod assembly;

[0031] S3. The height of the right end of the rotating seat rises, causing the wheel mounting platform to slide to the left along the upper surface of the rotating seat. At this time, the conductive post loses contact with the conductive component, disconnecting the power supply to the drive cylinder, causing the rotating seat to stop rotating immediately.

[0032] S4. Measure the angle of the rotating seat relative to the horizontal plane using the angle measuring component, and then calculate the sliding friction coefficient of the wheel on the wheel mounting platform.

[0033] Compared with the prior art, the beneficial effects of the present invention are: when assembling the wheel mounting platform, the clamping component and the lifting component are cleverly designed. Simply place the counterweight on the lifting component to easily clamp and fix the wheel component. Then, remove the counterweight and the wheel component. No complicated debugging or professional skills are required, which can improve the measurement efficiency.

[0034] When the wheel mounting platform slides on the rotating seat, the conductive post disengages from the conductive component, promptly cutting off the drive power and ensuring that the rotating seat stops at the correct angle. This precise control of the sliding stop position further improves the accuracy of angle measurement and provides a strong guarantee for accurately calculating the wheel's sliding friction coefficient. Attached Figure Description

[0035] Figure 1This is a three-dimensional structural diagram of the rotating base of the present invention when it is placed horizontally;

[0036] Figure 2 This is a schematic diagram of the rotating base of the present invention;

[0037] Figure 3 For the present invention Figure 2 A schematic diagram of the three-dimensional structure from another perspective;

[0038] Figure 4 This is a schematic diagram of the connection between the rotating seat and the sliding connecting rod assembly of the present invention;

[0039] Figure 5 This is an exploded structural diagram of the wheel mounting platform of the present invention;

[0040] Figure 6 This is a schematic diagram of the assembly structure of the lower fixing base in the initial state of the present invention;

[0041] Figure 7 A schematic diagram of the structure of the top fixing base of the present invention;

[0042] Figure 8 This is a schematic diagram of the connection between the lower fixed base, the disc, and the lifting column of the present invention;

[0043] Figure 9 For the present invention Figure 6 A schematic diagram of the cross-sectional structure;

[0044] Figure 10 This is a schematic diagram of the overall assembly structure of the wheel mounting platform of the present invention;

[0045] Figure 11 For the present invention Figure 10 A schematic diagram of the cross-sectional structure;

[0046] Figure 12 This is a schematic diagram of the structure of the rotating seat after rotation according to the present invention;

[0047] Figure 13 This is a schematic diagram of the force analysis structure of the wheel mounting platform after the rotating seat of the present invention rotates.

[0048] In the diagram: 1. Base; 2. Crossbeam; 3. Drive cylinder; 4. Support leg; 5. Slide groove; 6. Sliding connecting rod assembly; 61. Piston rod; 62. Connecting seat; 63. First pin; 64. Connecting lug; 65. Roller; 66. Slide seat; 67. Push rod; 68. Second pin; 7. Wheel mounting platform; 701. Fixed shaft; 702. Limiting annular groove; 703. Wheel to be tested; 704. Nut; 705. Sliding seat; 706. Conductive post; 707. Protrusion; 708. Lower fixed seat; 709. Top fixed seat; 711. Lifting mechanism 712. Column; 713. Counterweight; 714. Magnet; 715. Support plate; 716. Return spring; 717. Opening slot; 718. Protruding plate; 719. Disc; 720. Annular groove; 721. Connecting shaft; 722. L-shaped connecting arm; 723. Limiting ball; 8. Baffle; 9. Rotating seat; 10. Rotating shaft; 11. Protractor; 12. Vertical plate; 13. Angle indicator arrow; 14. Extension column; 15. Arc-shaped slot; 16. Limiting groove; 17. Long bar electromagnet; 18. Through hole; 19. Conductive sheet; 20. Terminal post; 21. Standing lug. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0050] Please see Figure 1-13 The present invention provides a technical solution:

[0051] A wheel sliding friction coefficient measuring device includes a base 1, a support leg 4 at the bottom of the base 1, and a rotating seat 9 movably connected to the upper left side of the base 1 via a vertical plate 12. The left end of the rotating seat 9 is movably connected to the vertical plate 12 via a rotating shaft 10.

[0052] An angle measuring component is provided between the left end of the rotating seat 9 and the vertical plate 12. The angle measuring component is used to measure the angle between the rotating seat 9 and the horizontal ground.

[0053] The angle measuring assembly includes a protractor 11 fixed to the side of the upright plate 12 and an angle indicator arrow 13 fixed to the side of the rotating seat 9 by an extension column 14, the extension column 14 extending through an arc-shaped slot 15 on the protractor 11.

[0054] When the rotating seat 9 is supported on the top of the horizontal frame 2 and is in a horizontal position, the angle indicator arrow 13 will point to the scale position of the corresponding horizontal angle on the protractor 11. This position can generally be set as the starting point of angle measurement, that is, the angle is 0°.

[0055] Rotation process: The drive cylinder 3 works, which drives the rotating seat 9 to rotate around the rotating shaft 10 at its left end through the sliding connecting rod assembly. Since the angle indicator arrow 13 is fixed to the rotating seat 9 through the extension column 14, the angle indicator arrow 13 will move together with the rotating seat 9 when the rotating seat 9 rotates.

[0056] Angle indication: During the rotation of the rotating seat 9, the extension column 14 will slide in the arc-shaped slot 15 of the protractor 11, and the angle indication arrow 13 will move on the scale of the protractor 11 to indicate the angle that the rotating seat 9 has rotated relative to the initial horizontal position.

[0057] Angle reading and recording: When the wheel mounting platform 7 slides to the left along the upper surface of the rotating seat 9, the conductive post 706 disengages from the conductive component, and the drive cylinder 3 is de-energized, causing the rotating seat 9 to stop rotating, the angle indicator arrow 13 can be read directly from the protractor 11. This value is the angle θ of the rotating seat 9 relative to the horizontal plane. This angle data will be used to subsequently calculate the wheel sliding friction coefficient of the wheel mounting platform 7.

[0058] The angle measurement component can intuitively and accurately measure the angle between the rotating seat 9 and the horizontal ground, providing key data for subsequent calculation of the wheel's sliding friction coefficient.

[0059] The upper middle part of the base 1 has a drive cylinder 3 in the cross frame seat 2. The drive cylinder 3 is an electric telescopic rod to meet the usage requirements. The cross frame seat 2 is used to provide horizontal support for the rotating seat 9. The output end of the drive cylinder 3 is movably connected to the bottom right end of the rotating seat 9 by a sliding connecting rod assembly 6.

[0060] The upper right side of the base 1 is provided with a slide groove 5. The sliding link assembly 6 includes a slide seat 66 that slides in the slide groove 5, a top rod 67 that is movably connected to the upper end of the slide seat 66 by a connecting ear 64, and a connecting seat 62 that is movably connected to the outside of the connecting ear 64.

[0061] The connecting seat 62 is fixedly connected to the piston rod 61 of the drive cylinder 3. The first pin 63 at the lower end of the push rod 67 passes through the connecting lug 64 and the connecting seat 62. The second pin 68 at the upper end of the push rod 67 is movably connected to the vertical lug 21 at the bottom right side of the rotating seat 9.

[0062] The bottom of the slide block 66 is provided with several sets of rollers 65 at equal intervals, and the rollers 65 are supported on the bottom wall of the slide groove 5.

[0063] The sliding linkage assembly converts the linear motion of the piston rod 61 of the drive cylinder 3 into the rotational motion of the rotating seat 9. In this process, components such as the push rod 67, connecting lug 64, and connecting seat 62 constitute a lever system. When the drive cylinder 3 applies a small force to the connecting seat 62, a large torque is generated on the rotating seat 9 through the action of the push rod 67, thereby driving the rotating seat 9 to rotate. This is because the distance between the second pin 68 (the connection point between the push rod 67 and the rotating seat 9) and the connecting lug 21 to the rotating shaft 10 may be longer than the lever arm of the piston rod 61 of the drive cylinder 3. According to the lever principle, with a longer lever arm, a smaller force can generate a larger torque, achieving a labor-saving effect.

[0064] Change in direction of motion: The sliding link assembly allows the force of the drive cylinder 3 to be transmitted in a direction more conducive to driving the rotating seat 9 to rotate. The linear motion direction of the drive cylinder 3 may not be consistent with the optimal direction for directly driving the rotating seat 9 to rotate, but the sliding link assembly can adjust the direction of the force, so that the force acts more effectively on the rotating seat 9, reducing the waste of force, and thus achieving a certain degree of force saving.

[0065] Other benefits of sliding link assemblies:

[0066] Motion stability:

[0067] Several sets of rollers 65, evenly spaced at the bottom of the slide block 66, support the bottom wall of the slide groove 5. The rollers 65 can reduce the friction between the slide block 66 and the slide groove 5, making the slide block 66 slide more smoothly in the slide groove 5.

[0068] Smooth motion conversion: The various components in the sliding linkage assembly are movably connected by the first pin 63 and the second pin 68. This movable connection method enables the linear motion of the drive cylinder 3 to be smoothly converted into the rotational motion of the rotating seat 9, avoiding abrupt changes and jamming during the motion process and improving the operational stability of the device.

[0069] Flexibility and adjustability:

[0070] Adaptable to different working conditions: The structural design of the sliding linkage assembly allows the rotation angle of the rotating seat 9 to be adjusted as needed. By changing the stroke of the piston rod 61 of the drive cylinder 3, the rotation angle of the rotating seat 9 can be controlled to adapt to different measurement requirements. For example, for different types of wheels 703 to be tested, different tilt angles may be required to measure their sliding friction coefficient, and the sliding linkage assembly can easily achieve this angle adjustment.

[0071] Easy to install and maintain: The components of the sliding linkage assembly are relatively independent and connected by pins, facilitating disassembly and installation. During installation, the device can be flexibly assembled according to actual conditions; during maintenance, if a component is damaged, it can be easily replaced, reducing maintenance costs and difficulty.

[0072] Uniformity of force distribution and transmission:

[0073] Stress Dispersion: The sliding linkage assembly distributes the force of the drive cylinder 3 to multiple components, avoiding localized stress concentration. For example, the force of the drive cylinder 3 is transmitted to the connecting lug 64 through the connecting seat 62, and then to the rotating seat 9 through the push rod 67. This distributed transmission method reduces the stress on each component, improving the service life of the components and the reliability of the device.

[0074] Ensuring rotational stability: Due to the uniform distribution and transmission of force, the rotating seat 9 experiences more uniform force on various parts during rotation, which ensures the stability and accuracy of rotation, thereby improving the accuracy of wheel sliding friction coefficient measurement.

[0075] A wheel mounting platform 7 is placed on the upper right side of the rotating seat 9. The wheel mounting platform 7 includes a sliding seat 705, wheel assemblies fixed at both ends of the sliding seat 705 by clamping components, and a conductive post 706 provided on the right side of the sliding seat 705.

[0076] A limiting groove 16 is provided on the upper right side of the rotating seat 9. Long electromagnets 17 are provided on the front and rear side walls of the limiting groove 16. A baffle 8 is provided on the left end of the limiting groove 16.

[0077] The bottom of the sliding seat 705 is provided with a protrusion 707, which extends into the limiting groove 16. Magnets 713 are provided on the front and rear side walls of the protrusion 707, and the magnets 713 and the corresponding long electromagnets 17 repel each other.

[0078] Reduce friction when the wheel mounting platform 7 slides:

[0079] Reducing additional friction interference: When the wheel mounting platform 7 slides on the rotating seat 9, the repulsive force between the long electromagnet 17 and the magnet 713 prevents the protrusion 707 from directly contacting the side wall of the limiting groove 16. Traditional mechanical limiting methods may cause sliding friction between the wheel mounting platform 7 and the limiting structure. This additional frictional force is superimposed on the frictional force between the wheel and the surface of the rotating seat 9, interfering with the measurement of the wheel's true sliding friction force. However, using magnetic repulsion to achieve non-contact limiting eliminates this additional friction interference, making the measured frictional force closer to the wheel's own sliding friction force, thereby improving the accuracy of the sliding friction coefficient measurement.

[0080] Ensuring the stability of the coefficient of friction: During sliding, additional mechanical friction can change with factors such as sliding distance and speed, leading to unstable friction. Magnetic repulsion provides a stable, non-contact environment, making the friction between the wheel and the rotating seat 9 surface more stable. Stable friction is crucial for accurately measuring the coefficient of sliding friction, as its calculation formula is based on the relationship between stable friction and normal force; fluctuations in friction can cause deviations in the calculation results. By reducing additional friction, the stability of the friction is ensured, thereby improving the accuracy of the coefficient of sliding friction measurement.

[0081] Prevent wheel mounting platform 7 from sliding or shifting:

[0082] Ensuring an accurate sliding path: During the sliding process of the wheel mounting platform 7, the mutual repulsion between the long electromagnet 17 and the magnet 713 allows the wheel mounting platform 7 to slide along a predetermined path. Without this limiting effect, the wheel mounting platform 7 may slide off course due to various factors such as minor unevenness on the surface of the rotating seat 9 or minor deviations in wheel installation. Offsets in the sliding path will cause changes in the contact state between the wheel and the surface of the rotating seat 9, thus affecting the magnitude and direction of the frictional force. An accurate sliding path ensures a stable contact state between the wheel 703 under test and the surface of the rotating seat 9, making the measured frictional force more accurately reflect the true sliding friction characteristics of the wheel 703 under test, thereby improving the accuracy of the sliding friction coefficient measurement.

[0083] Improving Angle Measurement Accuracy: Measuring the sliding friction coefficient of a wheel typically requires accurately measuring the angle of the rotating seat 9 relative to the horizontal plane. When the wheel mounting platform 7 slides off-center, it may affect the balance of the rotating seat 9, leading to errors in angle measurement. The magnetic repulsion limiting effect ensures that the wheel mounting platform 7 does not significantly interfere with the balance of the rotating seat 9 during sliding, allowing the angle measurement component to accurately measure the angle of the rotating seat 9. Accurate angle measurement is crucial for calculating the wheel's sliding friction coefficient because the angle is closely related to the gravitational component and normal force acting on the wheel 703 under test; errors in angle measurement directly lead to deviations in the calculated sliding friction coefficient. Therefore, preventing the wheel mounting platform 7 from sliding off-center helps improve the accuracy of angle measurement, thereby improving the accuracy of the sliding friction coefficient measurement.

[0084] The clamping assembly includes a top fixing seat 709 fixed at the left and right ends of the sliding seat 705, a lower fixing seat 708 movably connected to the sliding seat 705, and a limiting ball 722 fixed to the side of the lower fixing seat 708 by an L-shaped connecting arm 721.

[0085] The sliding seat 705 has an opening groove 716 inside, and a protrusion 717 is provided on the top of the opening groove 716. The lower fixed seat 708 is movably connected to the protrusion 717 by a connecting shaft 720, so that the lower fixed seat 708 is located directly below the corresponding top fixed seat 709.

[0086] The wheel assembly includes a fixed shaft 701 and wheels 703 to be tested that are sleeved on both ends of the fixed shaft 701;

[0087] The wheel 703 to be tested is installed at both ends of the fixed shaft 701 using nuts 704;

[0088] The fixed shaft 701 is symmetrically provided with limiting annular grooves 702, and after the lower fixed seat 708 closes upward with the corresponding top fixed seat 709, the lower fixed seat 708 and the corresponding top fixed seat 709 are stuck in the limiting annular grooves 702.

[0089] A lifting assembly is connected between the clamping assemblies. After the counterweight 712 is placed on the lifting assembly, the clamping assembly clamps and fixes the wheel assembly.

[0090] The lifting assembly includes a lifting column 711 extending through and out of the sliding seat 705, a support plate 714 disposed on the lifting column 711, a return spring 715 sleeved on the lifting column 711, and a disc 718 fixed after the bottom of the lifting column 711 extends into the opening slot 716.

[0091] The reset spring 715 is located at the top of the sliding seat 705 and the bottom of the support plate 714;

[0092] The limiting ball 722 is engaged in the annular groove 719 on the side of the disc 718.

[0093] Preliminary assembly of wheel components:

[0094] The wheel to be tested 703 is fitted onto both ends of the fixed shaft 701, and then the wheel to be tested 703 is installed on the fixed shaft 701 with the nut 704 to ensure that the wheel to be tested 703 is firmly installed on the fixed shaft 701.

[0095] like Figure 6 and 9 As shown, in the initial state, under the elastic force of the return spring 715 on the support plate 714, the lifting column 711 drives the disc 718 to move upward, thereby causing the disc 718 to drive the lower fixed seat 708 to rotate downward and open around the connecting shaft 720 through the limit ball 722 and the L-shaped connecting arm 721, in preparation for the subsequent clamping of the wheel assembly.

[0096] Place the wheel assembly into the clamping assembly:

[0097] The pre-assembled wheel assembly is placed between the lower fixed seat 708 and the top fixed seat 709. The wheel assembly is mainly placed on the lower fixed seat 708, so that the limiting annular groove 702 on the fixed shaft 701 is aligned with the lower fixed seat 708 and the top fixed seat 709.

[0098] Place the counterweight and clamp it:

[0099] A counterweight 712 is placed on the support plate 714 of the lifting column 711. As the weight of the counterweight 712 increases, the lifting column 711 will move downward, compressing the return spring 715.

[0100] The disc 718 at the bottom of the lifting column 711 also moves downwards. Since the limiting ball 722 is stuck in the annular groove 719 of the disc 718, the downward movement of the disc 718 will drive the lower fixing seat 708 to rotate upwards around the connecting shaft 720. Finally, the lower fixing seat 708 and the top fixing seat 709 close together and are tightly stuck in the limiting annular groove 702 of the fixing shaft 701, thereby clamping and fixing the wheel assembly.

[0101] After placing the wheel mounting platform 7 on the upper right side of the rotating seat 9, the wheel to be tested 703 contacts the upper right side surface of the rotating seat 9.

[0102] The clamping assembly, in conjunction with the lifting assembly, can easily clamp the wheel assembly by placing the counterweight 712, ensuring the stability of the wheel 703 under test during the measurement process.

[0103] A conductive component is provided at the right end of the rotating seat 9. The conductive post 706 contacts the conductive component to realize the power supply of the driving cylinder 3.

[0104] The conductive post 706 is fixed to the right end of the protrusion 707, and the right end of the limiting groove 16 is provided with a through hole 18.

[0105] The conductive component includes a conductive sheet 19 fixed to the right end of the rotating base 9 and a terminal block 20 fixed on the conductive sheet 19. The terminal block 20 is connected to the mains power by a push-button switch.

[0106] The conductive post 706 extends into the through hole 18 and then contacts the corresponding conductive sheet 19.

[0107] The conductive post 706, in conjunction with the conductive component, can control the energization and de-energization of the drive cylinder 3 according to the sliding state of the wheel mounting platform 7, thereby achieving automated operation.

[0108] During the sliding process of the wheel mounting platform 7, when the conductive post 706 disengages from the conductive component, the drive cylinder 3 is de-energized, causing the rotating seat 9 to stop rotating. The limiting effect of magnetic repulsion ensures that the wheel mounting platform 7 stops sliding at the appropriate position, thereby enabling the conductive post 706 to accurately disengage from the conductive component, promptly cutting off the drive power, and ensuring that the rotating seat 9 stops at the correct angle. This avoids inaccurate angle measurements caused by the rotating seat 9 continuing to rotate, thus improving the accuracy of the wheel sliding friction coefficient measurement.

[0109] The conductive post 706 works in conjunction to control the power supply and de-energization of the drive cylinder 3, ensuring that the device can stop the rotation of the rotating seat 9 in a timely manner according to the sliding state of the wheel mounting platform 7, thus ensuring the accuracy of the measurement.

[0110] Inclined plane method (sloping plane method):

[0111] Principle: By gradually increasing the tilt angle of the rotating seat 9 until the wheel 703 to be tested begins to slide or roll, the coefficient of friction is calculated using the critical angle.

[0112] step:

[0113] Place the wheel mounting platform 7 on the adjustable rotating seat 9.

[0114] Slowly increase the tilt angle θ of the rotating seat 9 until the wheel 703 to be tested begins to slide.

[0115] Calculate the coefficient of friction:

[0116] Coefficient of sliding friction: μs = tanθ.

[0117] like Figure 13 As shown, when the rotating seat 9 rotates and tilts, the wheel mounting platform 7 on it is subjected to the following forces:

[0118] Gravity mg: Vertically downwards, can be decomposed into:

[0119] The component of the force along the inclined plane (sliding force): mgsinθ;

[0120] The component of the force perpendicular to the inclined plane (normal force): mgcosθ;

[0121] Static friction force f: Upward along the inclined plane, it opposes sliding.

[0122] Support force N: The vertical reaction force applied by the inclined plane, N=mgcosθ.

[0123] At the critical state (when the wheel mounting platform 7 is about to slide but has not yet slided), the static friction reaches its maximum value f(max) and satisfies: f(max) = μsN.

[0124] Equilibrium condition:

[0125] In the critical state, the wheel mounting platform 7 is in equilibrium (acceleration is zero), therefore the net force along the rotating seat 9 is zero:

[0126] mgsinθ=f(max);

[0127] Substituting into the static friction formula:

[0128] mgsinθ=μsN;

[0129] Since N = mgcosθ, substituting it into the equation gives:

[0130] mgsinθ=μsmgcosθ

[0131] Divide both sides by mgcosθ (assuming cosθ≠0):

[0132] Sinθ / cosθ==μs;

[0133] From the trigonometric identity tanθ=sinθ / cosθ, we finally obtain:

[0134] The coefficient of sliding friction is μs = tanθ.

[0135] The present invention also provides a method for measuring the coefficient of sliding friction of a wheel, specifically including the following steps:

[0136] S1. The rotating seat 9 is supported on the top of the cross frame seat 2 to achieve the horizontal setting of the rotating seat 9. Then, the wheel mounting platform 7 is assembled and placed on the upper right side of the rotating seat 9 so that the conductive post 706 contacts the conductive component to realize the power supply of the drive cylinder 3.

[0137] After the conductive post 706 extends into the through hole 18, it contacts the corresponding conductive piece 19. The terminal 20 fixed on the conductive piece 19 is connected to the mains power by a push switch. In this way, the cylinder 3 can be powered on by pressing the push switch.

[0138] S2, drive the cylinder 3 to work, so that it drives the rotating seat 9 to rotate through the sliding connecting rod assembly 6;

[0139] S3. The height of the right end of the rotating seat 9 rises, causing the wheel mounting platform 7 to slide to the left along the upper surface of the rotating seat 9. At this time, the conductive post 706 disengages from the conductive component, disconnecting the power supply to the drive cylinder 3, causing the rotating seat 9 to stop rotating immediately.

[0140] S4. Measure the angle of the rotating seat 9 relative to the horizontal plane using the angle measuring component, and then calculate the coefficient of sliding friction of the wheel on the wheel mounting platform 7.

[0141] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for measuring the coefficient of sliding friction of a wheel, comprising a base, characterized in that: The upper left side of the base is movably connected to a rotating seat via a vertical plate. An angle measuring component is provided between the left end of the rotating seat and the vertical plate. The angle measuring component is used to measure the angle of the rotating seat relative to the horizontal ground. The upper middle part of the base is equipped with a drive cylinder. The cross frame is used to horizontally support the rotating seat. The output end of the drive cylinder is movably connected to the bottom right end of the rotating seat by a sliding linkage assembly. A wheel mounting platform is placed on the upper right side of the rotating seat. The wheel mounting platform includes a sliding seat, wheel assemblies fixed at both ends of the sliding seat by clamping components, and a conductive post on the right side of the sliding seat. A lifting component is connected between the clamping components. After a counterweight is placed on the lifting component, the clamping component clamps and fixes the wheel assembly. The right end of the rotating seat is provided with a conductive component, and the conductive post contacts the conductive component to realize the power supply of the driving cylinder. The left end of the rotating seat is movably connected between the vertical plates via a rotating shaft; The angle measuring component includes a protractor fixed to the side of the upright plate and an angle indicator arrow fixed to the side of the rotating seat by an extension column, the extension column extending through an arc-shaped slot on the protractor; The upper right side of the rotating seat is provided with a limiting groove, and long electromagnets are provided on the front and rear side walls of the limiting groove. A baffle is provided on the left end of the limiting groove. The bottom of the sliding seat is provided with a protrusion block that extends into the limiting groove. Magnets are provided on the front and rear side walls of the protrusion block, and the magnets and the corresponding long electromagnets repel each other. The conductive post is fixed to the right end of the protrusion, and a through hole is provided at the right end of the limiting groove. The conductive component includes a conductive sheet fixed to the right end of the rotating base and a terminal fixed on the conductive sheet. The terminal is connected to the mains power using a push-button switch. The conductive post extends into the through hole and then contacts the corresponding conductive sheet; The clamping assembly includes a top fixing seat fixed at both ends of the sliding seat, a lower fixing seat movably connected to the sliding seat, and a limiting ball fixed to the side of the lower fixing seat by an L-shaped connecting arm. The sliding seat has an opening groove inside, and a protruding plate is provided at the top of the opening groove. The lower fixed seat is movably connected to the protruding plate by a connecting shaft, so that the lower fixed seat is located directly below the corresponding upper fixed seat. The lifting assembly includes a lifting column extending through and out of the sliding seat, a support plate installed on the lifting column, a return spring sleeved on the lifting column, and a disc fixed after the bottom of the lifting column extends into the opening slot. The reset spring is located at the top of the sliding seat and the bottom of the support plate; The limiting ball is engaged in the annular groove on the side of the disk.

2. The wheel sliding friction coefficient measuring device according to claim 1, characterized in that: The upper right side of the base is provided with a sliding groove, and the sliding linkage assembly includes a sliding seat that slides in the sliding groove, a top rod that is movably connected to the upper end of the sliding seat by a connecting ear, and a connecting seat that is movably connected to the outside of the connecting ear. The connecting seat is fixedly connected to the piston rod of the drive cylinder. The first pin at the lower end of the push rod passes through the connecting lug and the connecting seat, and the second pin at the upper end of the push rod is movably connected to the vertical lug at the bottom right side of the rotating seat.

3. The wheel sliding friction coefficient measuring device according to claim 2, characterized in that: The bottom of the slide block is provided with several sets of rollers at equal intervals, and the rollers are supported on the bottom wall of the slide groove.

4. The wheel sliding friction coefficient measuring device according to claim 1, characterized in that: The wheel assembly includes a fixed axle and wheels to be tested sleeved on both ends of the fixed axle; The wheel to be tested is mounted on both ends of a fixed shaft using nuts; The fixed shaft is symmetrically provided with limiting annular grooves, and after the lower fixed seat closes with the corresponding top fixed seat upwards, the lower fixed seat and the corresponding top fixed seat are locked in the limiting annular grooves.

5. A method for measuring the coefficient of sliding friction of a wheel according to any one of claims 1-4, characterized in that: Specifically, the following steps are included: S1. The rotating seat is supported on the top of the cross frame to achieve a horizontal setting of the rotating seat. Then, the wheel mounting platform is assembled and placed on the upper right side of the rotating seat so that the conductive column contacts the conductive component to realize the power supply of the drive cylinder. S2. Drive the cylinder to work, causing it to rotate the rotating seat through the sliding connecting rod assembly; S3. The height of the right end of the rotating seat rises, causing the wheel mounting platform to slide to the left along the upper surface of the rotating seat. At this time, the conductive post loses contact with the conductive component, disconnecting the power supply to the drive cylinder, causing the rotating seat to stop rotating immediately. S4. Measure the angle of the rotating seat relative to the horizontal plane using the angle measuring component, and then calculate the sliding friction coefficient of the wheel on the wheel mounting platform.

Images