Real-time monitoring device and method for torque of small engine crankshaft

Abstract

In order to solve the problems that the existing transmission shaft torque detection bench cannot meet the small engine crankshaft monitoring and cannot carry out long-term real-time monitoring, the present application provides a small engine crankshaft torque real-time monitoring device and method.The small engine crankshaft torque real-time monitoring device comprises a strain gauge, a controller, a micro generator and a data receiving unit; the strain gauge is attached to the surface of the crankshaft on either side of the engine pulley; the controller is fixed on the side of the engine pulley and comprises a signal processing module, a transmitting module, a power module, a storage battery and a wifi module; and the micro generator is integrally installed on the inner side of the crankshaft end bearing.The present application has the beneficial technical effect that the torque of the small engine crankshaft under different load conditions can be monitored in real time, and the torque of the small engine crankshaft in actual operation can be monitored in real time for a long time.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of small engine crankshaft torque real-time monitoring technology, in particular to a kind of small engine crankshaft torque real-time monitoring device and method. BACKGROUND

[0002] Crankshaft is the important high-speed rotating transmission component of small engine, bears larger torque load, is the important component of engine torque transmission, and is indispensable component of engine timing system.If the serious deformation or fracture of crankshaft occurs in the operation of engine, it can cause serious accident.In the design and production process of crankshaft, in order to detect the torque bearing capacity of small engine crankshaft, the torque of small engine crankshaft under different loads is usually detected by laboratory transmission shaft torque detection bench, so as to design and produce better quality small engine crankshaft.The existing technology transmission shaft torque detection bench usually uses motor as power equipment, uses friction pair as load equipment, uses shaft coupling to connect the transmission shaft to be detected between power equipment and load equipment, and installs torque detection device on the outer circle of transmission shaft to be detected, thereby forming transmission shaft torque detection bench.The transmission shaft torque detection device is composed of two half circles similar to hoop, and is installed on the outer circle of transmission shaft during detection, and rotates with the transmission shaft, and the collected data is transmitted to data processing equipment by wired or wireless mode (see FIG. 1, in the figure, A is power equipment, B is shaft coupling, C is torque monitoring device, D is load equipment, and E is transmission shaft to be detected).Since the volume of such torque monitoring device is large, and it needs to be installed on a long transmission shaft, it cannot be applied to real-time monitoring of small engine crankshaft torque.In addition, since the strain gauge for detecting the surface strain of transmission shaft needs power supply, battery power supply is needed, so that the torque monitoring device needs to replace battery or charge battery after working for a period of time, and cannot be monitored for a long time. Figure 1

[0003] Obviously, the existing technology transmission shaft torque detection bench cannot meet the monitoring of small engine crankshaft and cannot be monitored for a long time. SUMMARY

[0004] To solve the problems that the existing technology transmission shaft torque detection bench cannot meet the monitoring of small engine crankshaft and cannot be monitored for a long time, the present application provides a kind of small engine crankshaft torque real-time monitoring device and method.

[0005] ​The application discloses a real-time monitoring device for the torque of a crankshaft of a small engine, which comprises a strain gauge, a controller, a micro generator and a data receiving unit; the strain gauge is attached to the surface of the crankshaft on either side of the engine pulley; the controller is fixed on the side of the engine pulley and comprises a signal processing module, a transmitting module, a power module, a storage battery and a WIFI module; the micro generator is a permanent magnet generator which comprises a rotor coil and a permanent magnet stator and is integrally installed on the inner side of the bearing at the end of the crankshaft; the rotor coil is fixed on the crankshaft and rotates with the crankshaft; the permanent magnet stator is fixed on the outer side of the crankcase or the engine base and does not rotate with the crankshaft; the controller is electrically connected with the strain gauge and the micro generator; the data receiving unit is wirelessly connected with the WIFI module of the controller; the crankshaft refers to the crankshaft of a small engine which has been installed and can normally operate; and the data receiving unit comprises a mobile phone and a notebook computer.

[0006] Further, the strain gauge is a foil full-bridge strain gauge with the model BF1000-3EB, the resistance of 1000 ohms, the substrate size of 10*8.5 mm, the strain limit of 20000 um / m and the working temperature of -20-80 DEG C.

[0007] Further, the strain gauge is attached to the surface of the crankshaft on either side of the engine pulley, and a strain conducting plate is arranged between the substrate of the strain gauge and the surface of the crankshaft, that is, the strain gauge is attached to the upper surface of the strain conducting plate, the lower surface of the strain conducting plate is attached to the surface of the crankshaft, and the rectangular plane required for attaching the strain gauge is not polished on the surface of the crankshaft; the upper surface of the strain conducting plate is matched with the substrate surface of the strain gauge, and the lower surface of the strain conducting plate is matched with the surface of the crankshaft; the matching refers to that the shapes and sizes of two planes or arc surfaces are the same, and the whole plane or arc surface is completely contacted without any gap when the two planes or arc surfaces coincide with each other.

[0008] Further, the lower surface of the strain conducting plate is provided with a cross-shaped groove, and the intersection of the cross-shaped groove coincides with the geometric center of the strain conducting plate.

[0009] Further, the micro generator is changed into a permanent magnet generator with the radial structure and the rotor coil integrated with the engine pulley, that is, a plurality of radial tooth grooves are arranged on one side of the inner step of the engine pulley, thereby forming the iron core of the rotor coil of the micro generator; the rotor coil of the micro generator is formed after the coil is embedded on the iron core; the permanent magnet stator is sleeved on the radial outer side of the rotor coil; and the permanent magnet stator is fixed on the outer side of the crankcase or the engine base through the base and does not rotate with the crankshaft.

[0010] Further, the micro generator is changed to an axial structure permanent magnet generator with the rotor coil integrated with the engine pulley, that is, a plurality of axial tooth grooves are arranged on one side of the step in the engine pulley, thereby forming the iron core of the micro generator rotor coil; the coil is embedded on the iron core to form the micro generator rotor coil; the permanent magnet stator is arranged side by side on the axial outer side of the micro generator rotor coil; the permanent magnet stator is fixed on the outer side of the crankcase or the machine base through the base and does not rotate with the crankshaft.

[0011] The small engine crankshaft torque real-time monitoring method adopts the small engine crankshaft torque real-time monitoring device to monitor the small engine crankshaft torque in real time, and includes the following steps:

[0012] S1, the strain gauge is pasted on the surface of the crankshaft on either side of the small engine pulley; wherein the crankshaft refers to the crankshaft that has been installed on the small engine that can normally operate; the strain gauge is a foil full-bridge strain gauge, the model is BF1000-3EB, the resistance is 1000 ohms, the substrate size is 10*8.5mm, the strain limit is 20000um / m, and the working suitable temperature is-20-80℃;

[0013] S2, the controller is fixed on the side of the pulley; wherein the controller includes a signal processing module, a transmitting module, a power module, a storage battery and a wifi module;

[0014] S3, the micro generator is installed on the inner side of the crankshaft end bearing; wherein the micro generator is a permanent magnet generator, including a rotor coil and a permanent magnet stator, the rotor coil is fixed on the crankshaft and rotates with the crankshaft; the permanent magnet stator is fixed on the crankcase and does not rotate with the crankshaft;

[0015] S4, the controller is electrically connected with the strain gauge and the micro generator respectively;

[0016] S5, the data receiving unit is wirelessly connected with the wifi module of the controller, and the working parameters of the controller and the strain gauge are set or debugged through the data receiving unit; wherein the data receiving unit includes a mobile phone and a notebook computer;

[0017] S6, after the debugging is completed, the small engine is connected with the adjustable load through the pulley; or, step S9 is executed;

[0018] S7, the small engine is started, and the load is adjusted to different set values, at the same time, the torque value is detected and recorded;

[0019] S8, according to the detection needs, step S7 is repeatedly executed until the detection is completed;

[0020] S9, assemble the small engine to the actual running machine; the actual running machine includes a small generator, a small sprinkler, a small water pump, a small tractor, a small transplanter and a small plough;

[0021] S10, put the actual running machine into actual operation, and receive torque data of the crankshaft in actual operation through a data receiving unit.

[0022] Further, the strain gauge is pasted on the surface of the crankshaft on either side of the small engine pulley, including the following steps:

[0023] S101, using an electric grinding head to grind a rectangular plane larger than the strain gauge base on the surface of the crankshaft on either side of the small engine pulley;

[0024] S102, draw a cross line on the rectangular surface with a steel needle, wherein the intersection of the cross line is the measurement point position, the axial cross line coincides with the crankshaft axis, and the radial cross line is perpendicular to the axial cross line;

[0025] S103, use 200# or finer sandpaper to grind the rectangular surface into a 45° cross line, and then use a pair of tweezers to hold an acetone cotton ball to scrub the rectangular surface until the cotton ball is white;

[0026] S104, apply strong glue to the rectangular surface, and paste the strain gauge base downward on the rectangular plane of the crankshaft; at the same time, ensure that the geometric center of the strain gauge is aligned with the cross line center of the rectangular plane; the long side of the strain gauge is parallel to the axial cross line, and the axial cross line is located at the center of the short side of the strain gauge; the short side of the strain gauge is parallel to the radial cross line, and the radial cross line is located at the center of the long side of the strain gauge;

[0027] S105, check the strain gauge for bubbles, warping and delamination, and then use a digital multimeter to check the strain gauge for short circuit, open circuit and resistance value change greater than 10% of the original resistance value; if there is no above phenomenon, it is considered qualified; otherwise, it needs to be re-pasted;

[0028] S106, connect the lead wire of the strain gauge to the controller through the lead wire, and coat a moisture-proof layer on the surface of the strain gauge, lead wire and lead wire, the moisture-proof layer includes epoxy resin and silicone rubber;

[0029] S107, after drying and curing, detect the outer tube and resistance value of the strain gauge again, and confirm that the pasting is qualified after ensuring that no phenomenon described in step S105 occurs.

[0030] Further, the step S1 of sticking the strain gauge on the crankshaft surface on either side of the small engine belt pulley comprises: arranging a strain conducting plate between the strain gauge base and the crankshaft surface, namely, sticking the strain gauge on the upper surface of the strain conducting plate when sticking, and sticking the lower surface of the strain conducting plate on the crankshaft surface, and not polishing a rectangular plane required for sticking the strain gauge on the crankshaft surface; the upper surface of the strain conducting plate is matched with the strain gauge base surface, and the lower surface of the strain conducting plate is matched with the crankshaft surface; the matching refers to that the shapes and sizes of the two planes or arc surfaces are the same, and when the two planes or arc surfaces coincide with each other, the whole plane or arc surface is completely contacted without any gap.

[0031] Further, the lower surface of the strain conducting plate is provided with a cross-shaped groove, and the intersection of the cross-shaped groove coincides with the geometric center of the strain conducting plate.

[0032] Further, the micro generator in the step S3 is replaced by a radial structure permanent magnet generator with the rotor coil integrated with the engine belt pulley, namely, a plurality of radial tooth grooves are arranged on one side of the inner step of the engine belt pulley, thereby forming the iron core of the micro generator rotor coil; the coil is embedded on the iron core to form the micro generator rotor coil; the permanent magnet stator is sleeved on the radial outer side of the micro generator rotor coil; the permanent magnet stator is fixed on the outer side of the crankcase or the machine base through the base foot, and does not rotate with the crankshaft.

[0033] Further, the micro generator in the step S3 is replaced by an axial structure permanent magnet generator with the rotor coil integrated with the engine belt pulley, namely, a plurality of axial tooth grooves are arranged on one side of the inner step of the engine belt pulley, thereby forming the iron core of the micro generator rotor coil; the coil is embedded on the iron core to form the micro generator rotor coil; the permanent magnet stator is arranged in parallel on the axial outer side of the micro generator rotor coil; the permanent magnet stator is fixed on the outer side of the crankcase or the machine base through the base foot, and does not rotate with the crankshaft.

[0034] The beneficial technical effects of the small engine crankshaft torque real-time monitoring device and method are that the torque of the small engine crankshaft under different load conditions can be monitored in real time, and the torque borne by the small engine crankshaft in actual operation can be monitored in real time for a long time. BRIEF DESCRIPTION OF DRAWINGS

[0035] FIG. 1 is a structural schematic diagram of a prior art transmission shaft torque detection bench; Figure 1 FIG. 2 is a three-dimensional schematic diagram of the small engine crankshaft torque real-time monitoring device of the application installed on the crankshaft;

[0036] FIG. 3 is a three-dimensional schematic diagram of the small engine crankshaft torque real-time monitoring device of the application installed on the crankshaft; Figure 2

[0037] Figure 3 ​​is a three-dimensional schematic view of the small engine crankshaft torque real-time monitoring device of the present application installed on the crankshaft from another angle;

[0038] attached Figure 4 is a structural block diagram of the small engine crankshaft torque real-time monitoring device of the present application;

[0039] attached Figure 5 is a three-dimensional schematic view of the strain gauge installation of the present application;

[0040] attached Figure 6 is a three-dimensional schematic view of the strain conduction plate installation of the present application;

[0041] attached Figure 7 is a three-dimensional schematic view of the strain conduction plate cross-groove of the present application;

[0042] attached Figure 8 is a three-dimensional schematic view of the radial structure of the micro-generator rotor coil and engine pulley of the present application;

[0043] attached Figure 9 is a three-dimensional schematic view of the axial structure of the micro-generator rotor coil and engine pulley of the present application.

[0044] The small engine crankshaft torque real-time monitoring device and method of the present application will be further described below in conjunction with the drawings and specific embodiments. DETAILED DESCRIPTION

[0045] attached Figure 1 is a structural schematic view of the existing technology transmission shaft torque detection bench, attached Figure 2 is a three-dimensional schematic view of the small engine crankshaft torque real-time monitoring device of the present application installed on the crankshaft, attached Figure 3 is a three-dimensional schematic view of the small engine crankshaft torque real-time monitoring device of the present application installed on the crankshaft from another angle, attached Figure 4It is structural diagram of small engine crankshaft torque real-time monitoring device of the application, in drawing, 1 is crankshaft, 2 is engine pulley, 3 is strain gauge, 4 is controller, 5 is micro generator. As can be known from the drawing, the small engine crankshaft torque real-time monitoring device of the application, comprising, strain gauge 3, controller 4, micro generator 5 and data receiving unit;The strain gauge 3 is pasted on the surface of the crankshaft on either side of the engine pulley;The controller 4 is fixed on the side of the engine pulley, comprising, signal processing module, transmitting module, power module, storage battery and wifi module;The micro generator 5 is permanent magnet generator, comprising, rotor coil and permanent magnet stator, and the whole is installed on the inner side of the crankshaft end head bearing;Among them, the rotor coil is fixed on the crankshaft, and rotates with the crankshaft;The permanent magnet stator is fixed on the outside of the crankcase or the machine base, and does not rotate with the crankshaft;The controller is electrically connected with the strain gauge and the micro generator respectively;The data receiving unit is wirelessly connected with the wifi module of the controller;Among them, the crankshaft refers to the crankshaft that has been installed on the small engine that can run normally;The data receiving unit comprises mobile phone and notebook computer. The small engine crankshaft torque real-time monitoring device of the application, each component is fixed and installed near the engine pulley that can run normally, and is electrically connected to form a complete monitoring device, so that the torque of the small engine crankshaft under different load conditions can be detected in real time by applying different loads to the engine. Or, the small engine is installed on a kind of machinery such as generator and tractor that can actually run, and the torque of the small engine crankshaft in actual operation is long-term monitored in real time.

[0046] As one of the preferred schemes, the strain gauge is foil full-bridge strain gauge, model number is BF1000-3EB, resistance is 1000 ohms, substrate size is 10*8.5mm, strain limit is 20000um / m, and working suitable temperature is -20-80℃.

[0047] Attached Figure 5 It is three-dimensional schematic view of strain gauge installation of the application, attached Figure 6 It is three-dimensional schematic view of strain gauge installation of the application, attached Figure 7This is a three-dimensional schematic diagram of the cross-shaped groove of the strain transmission plate of the present invention; in the figure, 1 is the crankshaft, 3 is the strain gauge, and 6 is the strain transmission plate. As shown in the figure, the strain gauge is flat, and its base is a plane. In order to fully contact and adhere the strain gauge base to the crankshaft surface, a plane of a size matching the strain gauge base needs to be machined on the crankshaft surface. Since the diameter of the section of the crankshaft where the pulley is mounted is small, machining the plane will cause significant damage to the crankshaft itself, potentially reducing the crankshaft's torque carrying capacity. On the other hand, as the crankshaft surface changes from curved to flat, its stress-strain pattern will also change. In this case, the detected torque may differ significantly from the actual value. To address the aforementioned issues, as a preferred solution, the strain gauge is adhered to the crankshaft surface on either side of the pulley of a small engine. This involves placing a strain transmission plate between the strain gauge substrate and the crankshaft surface. Specifically, during adhesion, the strain gauge is adhered to the upper surface of the strain transmission plate, while the lower surface of the strain transmission plate is adhered to the crankshaft surface, without grinding a rectangular plane on the crankshaft surface to accommodate the strain gauge. The upper surface of the strain transmission plate matches the strain gauge substrate surface, and the lower surface of the strain transmission plate matches the crankshaft surface. This matching means that the two planes or arc surfaces have the same shape and size, and when they overlap, the entire plane or arc surface is in complete contact without any gaps. Using this method, torque can be detected without damaging the crankshaft surface, maintaining the crankshaft's torque carrying capacity and preventing the detection results from significantly deviating from actual conditions. To improve the sensitivity of the strain transmission plate, the lower surface of the strain transmission plate is provided with a cross-shaped groove, and the intersection of the cross-shaped groove coincides with the geometric center of the strain transmission plate. In this way, even small strains on the crankshaft surface can be transmitted to the strain gauge substrate, improving the sensitivity of the detection.

[0048] Appendix Figure 8 This is a three-dimensional schematic diagram of the radial structure of the micro generator rotor coil and the engine pulley integrated into one unit according to the present invention. In the figure, 1 is the crankshaft, 2 is the generator pulley, 7-1 is the radial rotor coil, 7-2 is the radial permanent magnet stator, and 7-3 is the cover plate. As shown in the figure, as one of the improved solutions, the micro generator is changed to a permanent magnet generator with a radial structure in which the rotor coil and the engine pulley are integrated into one unit. Specifically, several radial grooves are set on one side of the step inside the engine pulley, thereby forming the iron core of the micro generator rotor coil; the coil is embedded in the iron core to form the rotor coil of the micro generator; the permanent magnet stator is fitted on the radial outer side of the rotor coil; the permanent magnet stator is fixed to the outside of the crankcase or the base by the base feet and does not rotate with the crankshaft. After the improvement, the micro generator can be greatly simplified, and at the same time, the structure of the entire device is simplified, and the operational reliability of the entire device is improved.

[0049] Appendix Figure 9It is three-dimensional schematic view of axial structure of micro generator rotor coil and engine pulley, in the drawing, 1 is crankshaft, 2 is generator pulley, 7-1 is axial rotor coil, 7-2 is axial permanent magnet stator. As one of the improved schemes, the micro generator is changed into axial structure of permanent magnet generator of rotor coil and engine pulley, that is, a plurality of axial tooth grooves are arranged on one side of the step in the engine pulley, thereby forming the core of the micro generator rotor coil;After embedding the coil on the core, the micro generator rotor coil is formed;The permanent magnet stator is arranged side by side on the axial outer side of the micro generator rotor coil;The permanent magnet stator is fixed on the outer side of the crankcase or the machine base through the base, and does not rotate with the crankshaft. The micro generator is changed into axial structure of permanent magnet generator of rotor coil and engine pulley, in addition to various advantages of changing into radial structure, it also has the advantages of simple processing and convenient assembly.

[0050] The small engine crankshaft torque real-time monitoring method adopts the small engine crankshaft torque real-time monitoring device to monitor the small engine crankshaft torque in real time, including the following steps:

[0051] S1, the strain gauge is pasted on the surface of the crankshaft on either side of the small engine pulley;Wherein, the crankshaft refers to the crankshaft installed on the small engine which can run normally;The strain gauge is foil full-bridge strain gauge, model BF1000-3EB, resistance 1000 ohm, base size 10*8.5mm, strain limit 20000um / m, and working temperature-20-80℃;

[0052] S2, the controller is fixed on the side of the pulley;Wherein, the controller includes signal processing module, transmitting module, power module, storage battery and wifi module;

[0053] S3, the micro generator is installed on the inner side of the crankshaft end bearing;Wherein, the micro generator is a permanent magnet generator, including rotor coil and permanent magnet stator, the rotor coil is fixed on the crankshaft and rotates with the crankshaft;The permanent magnet stator is fixed on the crankcase and does not rotate with the crankshaft;

[0054] S4, the controller is electrically connected with the strain gauge and the micro generator respectively;

[0055] S5, the data receiving unit is wirelessly connected with the wifi module of the controller, and the working parameters of the controller and the strain gauge are set or debugged through the data receiving unit;Wherein, the data receiving unit includes mobile phone and notebook computer;

[0056] S6, after debugging, the small engine is connected with the adjustable load through the pulley;Or, execute step S9.

[0057] S7, start the small engine and adjust the load to different set values while detecting and recording the torque values;

[0058] S8, repeat step S7 according to the detection needs until the detection is completed;

[0059] S9, assemble the small engine to the actual running machine, including small generator, small sprinkler, small water pump, small tractor, small transplanter and small cultivator;

[0060] S10, put the actual running machine into actual operation and receive the torque data of the crankshaft in actual operation through the data receiving unit.

[0061] In order to ensure that the strain gauge can sensitively and effectively detect the small strain on the surface of the crankshaft, the strain gauge needs to be pasted on the surface of the crankshaft, that is, pasted on the surface of the crankshaft on either side of the small engine pulley, including the following steps:

[0062] S101, use an electric grinding head to grind a rectangular plane larger than the strain gauge base on the surface of the crankshaft on either side of the small engine pulley;

[0063] S102, draw a cross line on the rectangular surface with a steel needle, wherein the intersection of the cross line is the measurement point position, the axial cross line coincides with the crankshaft axis, and the radial cross line is perpendicular to the axial cross line;

[0064] S103, use 200# or finer sandpaper to grind the rectangular surface into a 45° cross line, and then use tweezers to hold a cotton ball soaked in acetone to clean the rectangular surface until the cotton ball is white;

[0065] S104, apply strong glue to the rectangular surface and paste the strain gauge base downward on the rectangular plane of the crankshaft; at the same time, ensure that the geometric center of the strain gauge is aligned with the center of the cross line of the rectangular plane; the long side of the strain gauge is parallel to the axial cross line, and the axial cross line is located at the center of the short side of the strain gauge; the short side of the strain gauge is parallel to the radial cross line, and the radial cross line is located at the center of the long side of the strain gauge;

[0066] S105, check the strain gauge for bubbles, warping and delamination, and then use a digital multimeter to check the strain gauge for short circuit, open circuit and resistance value change greater than 10% of the original resistance value; if there is no above phenomenon, it is considered qualified; otherwise, it needs to be re-pasted;

[0067] S106, connect the lead wire of the strain gauge to the controller through the lead wire, and coat a moisture-proof layer on the surface of the strain gauge, lead wire and lead wire, the moisture-proof layer including epoxy resin and silicone rubber;

[0068] S107. After drying and curing, the outer tube and resistance of the strain gauge are tested again to ensure that none of the phenomena described in step S105 occur, and the bonding is confirmed to be qualified.

[0069] Clearly, to ensure adequate contact and adhesion between the strain gauge substrate and the crankshaft surface, a flat surface matching the size of the strain gauge substrate needs to be machined on the crankshaft surface. Since the diameter of the section of the crankshaft where the pulley is mounted is relatively small, machining this flat surface would cause significant damage to the crankshaft itself, potentially reducing its torque-carrying capacity. Furthermore, changing the crankshaft surface from curved to flat alters its stress-strain pattern, potentially leading to a significant discrepancy between the detected torque and the actual torque. To address the aforementioned issues, as a preferred solution, step S1, which involves attaching the strain gauge to the crankshaft surface on either side of the pulley of a small engine, includes placing a strain transmission plate between the strain gauge substrate and the crankshaft surface. Specifically, during attachment, the strain gauge is attached to the upper surface of the strain transmission plate, while the lower surface of the strain transmission plate is attached to the crankshaft surface, without grinding a rectangular plane on the crankshaft surface to accommodate the strain gauge. The upper surface of the strain transmission plate matches the surface of the strain gauge substrate, and the lower surface of the strain transmission plate matches the surface of the crankshaft. This matching means that the two planes or arc surfaces have the same shape and size, and when they overlap, the entire plane or arc surface is in complete contact without any gaps. Furthermore, to improve the sensitivity of the strain transmission plate, the lower surface of the strain transmission plate is provided with a cross-shaped groove, and the intersection of the cross-shaped groove coincides with the geometric center of the strain transmission plate. This allows even small strains occurring on the crankshaft surface to be transmitted to the strain gauge substrate, improving detection sensitivity.

[0070] To further simplify the micro generator and the overall structure of the device, and to improve the operational reliability and stability of the entire device, the micro generator described in step S3 is replaced with a permanent magnet generator with a radial structure in which the rotor coil and the engine pulley are integrated. Specifically, several radial slots are provided on one side of the inner step of the engine pulley, thereby forming the core of the micro generator rotor coil. The coil is then embedded in the core to form the rotor coil of the micro generator. A permanent magnet stator is fitted radially on the outer side of the micro generator rotor coil. The permanent magnet stator is fixed to the outside of the crankcase or the base by a base foot and does not rotate with the crankshaft.

[0071] Similarly, the micro-generator described in step S3 can also be replaced by a rotor coil integrated with the engine pulley in an axial structure of a permanent magnet generator, that is, a plurality of axial tooth grooves are arranged on one side of the step in the engine pulley, thereby forming the core of the micro-generator rotor coil; the coil is embedded on the core to form the micro-generator rotor coil; the permanent magnet stator is arranged side by side on the axial outer side of the micro-generator rotor coil; the permanent magnet stator is fixed on the outer side of the crankcase or the base through the base and does not rotate with the crankshaft. After the improvement, in addition to various advantages of the radial structure, it also has the advantages of simple processing and convenient assembly.

[0072] Obviously, the beneficial technical effects of the small engine crankshaft torque real-time monitoring device and method are that the torque of the small engine crankshaft under different load conditions can be monitored in real time, and the torque borne by the small engine crankshaft in actual operation can be monitored in real time for a long time.

Claims

1. A small engine crankshaft torque real-time monitoring device, characterized by, The monitoring device comprises a strain gauge, a controller, a micro-generator and a data receiving unit; the strain gauge is attached to the surface of the crankshaft on either side of the engine pulley; the controller is fixed on the side of the engine pulley and comprises a signal processing module, a transmitting module, a power module, a storage battery and a wifi module; the micro-generator is a permanent magnet generator and comprises a rotor coil and a permanent magnet stator, and is integrally installed on the inner side of the bearing of the crankshaft end head; the rotor coil is fixed on the crankshaft and rotates with the crankshaft; the permanent magnet stator is fixed on the outer side of the crankcase or the machine base and does not rotate with the crankshaft; the controller is electrically connected with the strain gauge and the micro-generator; the data receiving unit is wirelessly connected with the wifi module of the controller; the crankshaft refers to the crankshaft installed on a small engine which can operate normally; the data receiving unit comprises a mobile phone and a notebook computer; and the micro-generator is changed to a permanent magnet generator with the rotor coil and the engine pulley in a radial structure, i.e. a plurality of radial tooth grooves are arranged on one side of the step in the engine pulley to form the core of the rotor coil of the micro-generator; the rotor coil of the micro-generator is formed after the coil is embedded on the core; the permanent magnet stator is sleeved on the radial outer side of the rotor coil; the permanent magnet stator is fixed on the outer side of the crankcase or the machine base by a base and does not rotate with the crankshaft; or The micro-generator is changed to a permanent magnet generator with the rotor coil and the engine pulley in an axial structure, i.e. a plurality of axial tooth grooves are arranged on one side of the step in the engine pulley to form the core of the rotor coil of the micro-generator; the rotor coil of the micro-generator is formed after the coil is embedded on the core; the permanent magnet stator is arranged side by side on the axial outer side of the rotor coil of the micro-generator; the permanent magnet stator is fixed on the outer side of the crankcase or the machine base by a base and does not rotate with the crankshaft. The strain gauge is a foil full-bridge strain gauge with a model of BF1000-3EB, a resistance of 1000 ohms, a substrate size of 10*8.5mm, a strain limit of 20000um / m and a working temperature of -20-80℃. The strain gauge is attached to the surface of the crankshaft on either side of the engine pulley, and a strain conduction plate is arranged between the substrate of the strain gauge and the surface of the crankshaft, i.e. the strain gauge is attached to the upper surface of the strain conduction plate, the lower surface of the strain conduction plate is attached to the surface of the crankshaft, and no rectangular plane required for attaching the strain gauge is polished on the surface of the crankshaft; the upper surface of the strain conduction plate matches the surface of the substrate of the strain gauge, and the lower surface of the strain conduction plate matches the surface of the crankshaft; the matching refers to that the shapes and sizes of the two planes or curved surfaces are the same, and the whole plane or curved surface is completely contacted without any gap when the two planes or curved surfaces coincide with each other.

2. The device for real-time monitoring of the torque of the crankshaft of a small engine according to claim 1, characterized in that, The lower surface of the strain conduction plate is provided with a cross-shaped groove, and the intersection of the cross-shaped groove coincides with the geometric center of the strain conduction plate.

3. The device for real-time monitoring of the torque of the crankshaft of a small engine according to claim 1, characterized in that, The small engine crankshaft torque real-time monitoring device of claim 1 is used to monitor the torque of the small engine crankshaft in real time, comprising the following steps:

4. The device for real-time monitoring of the torque of the crankshaft of a small engine according to claim 3, characterized in that, ​ 5. A method of real-time monitoring of crankshaft torque in a small engine, characterized by, ​ S1, the strain gauge is pasted on the surface of the crankshaft on either side of the small engine pulley; wherein, the crankshaft refers to the crankshaft that has been installed on the small engine that can run normally; the strain gauge is a foil full-bridge strain gauge, the model is BF1000-3EB, the resistance is 1000 ohms, the substrate size is 10*8.5mm, the strain limit is 20000um / m, and the working suitable temperature is-20-80℃; S2, the controller is fixed on the side of the pulley; wherein, the controller comprises a signal processing module, a transmitting module, a power module, a storage battery and a wifi module; S3, the micro generator is installed on the inner side of the crankshaft end bearing; wherein, the micro generator is a permanent magnet generator, comprising a rotor coil and a permanent magnet stator, the rotor coil is fixed on the crankshaft and rotates with the crankshaft; the permanent magnet stator is fixed on the crankcase and does not rotate with the crankshaft; S4, the controller is electrically connected with the strain gauge and the micro generator respectively; S5, the data receiving unit is wirelessly connected with the wifi module of the controller, and the working parameters of the controller and the strain gauge are set or debugged through the data receiving unit; wherein, the data receiving unit comprises a mobile phone and a notebook computer; S6, after debugging, the small engine is connected with the adjustable load through the pulley; or, step S9 is executed; S7, the small engine is started, and the load is adjusted to different set values, at the same time, the torque value is detected and recorded; S8, according to the detection needs, step S7 is repeatedly executed until the detection is completed; S9, the small engine is assembled to the actual running machine; the actual running machine comprises a small generator, a small sprinkler, a small water pump, a small tractor, a small rice transplanter and a small plough; S10, the actual running machine is put into actual operation, and the torque data of the crankshaft in actual operation is received in real time through the data receiving unit.

6. The method of claim 5, wherein, The strain gauge is pasted on the surface of the crankshaft on either side of the small engine pulley in step S1, comprising the following steps: S101, a rectangular plane larger than the strain gauge substrate is polished on the surface of the crankshaft on either side of the small engine pulley by using an electric grinding head; S102, a cross line is drawn on the rectangular surface with a steel needle, wherein the intersection point of the cross line is the measurement point position, the axial cross line coincides with the crankshaft axis, and the radial cross line is perpendicular to the axial cross line; S103, the rectangular surface is polished into a 45° cross line by using 200# or below fine sandpaper, and then the rectangular surface is scrubbed clean by using a pair of tweezers to hold a cotton ball soaked with acetone, until the cotton ball is white; S104, the rectangular surface is coated with strong glue, and the strain gauge substrate is pasted on the rectangular plane of the crankshaft with the strain gauge substrate facing down; at the same time, the geometric center of the strain gauge is aligned with the center of the cross line of the rectangular plane; the long side of the strain gauge is parallel to the axial cross line, and the axial cross line is located at the center of the short side of the strain gauge; the short side of the strain gauge is parallel to the radial cross line, and the radial cross line is located at the center of the long side of the strain gauge; S105, check if there are bubbles, warping and delamination phenomenon of the appearance of the strain gauge, and then use a digital multimeter to check if there are short circuit, open circuit and resistance value change greater than 10% of the original resistance value; no above phenomenon, considered qualified; otherwise, need to re-paste; S106, through the wire connecting the lead wire of the strain gauge and the controller, and coating a moisture-proof layer on the surface of the strain gauge, lead wire and wire, the moisture-proof layer includes epoxy resin and silicone rubber; S107, after drying and curing, detect the outer tube and resistance value of the strain gauge again, and confirm the qualified paste after ensuring that no various phenomena described in step S105 occur.

7. The method of claim 5, wherein the step of monitoring the torque of the crankshaft of the small engine in real time is performed by a torque sensor. The step S1 described that the strain gauge is pasted on the surface of the crankshaft on either side of the small engine pulley, including, setting a strain conducting plate between the strain gauge base and the surface of the crankshaft, that is, pasting the strain gauge on the upper surface of the strain conducting plate when pasting, and pasting the lower surface of the strain conducting plate on the surface of the crankshaft, and not grinding a rectangular plane required for pasting the strain gauge on the surface of the crankshaft; the upper surface of the strain conducting plate matches the surface of the strain gauge base, and the lower surface of the strain conducting plate matches the surface of the crankshaft; the matching refers to the shape and size of the two planes or arc surfaces being the same, and when the two planes or arc surfaces coincide with each other, the whole plane or arc surface is completely contacted without any gap.

8. The method of claim 7, wherein the step of monitoring the torque of the crankshaft of the small engine in real time is performed by a torque sensor. A cross-shaped groove is arranged on the lower surface of the strain conducting plate, and the intersection of the cross-shaped groove coincides with the geometric center of the strain conducting plate.

9. The method of claim 8, wherein, The micro generator described in step S3 is replaced by a radial structure of a permanent magnet generator with the rotor coil and the engine pulley being integrated, that is, a plurality of radial tooth grooves are arranged on one side of the inner step of the engine pulley, thereby constituting the core of the rotor coil of the micro generator; the rotor coil of the micro generator is constituted after embedding the coil on the core; the permanent magnet stator is sleeved on the radial outer side of the rotor coil of the micro generator; the permanent magnet stator is fixed on the outer side of the crankcase or the base through the foot, and does not rotate with the crankshaft; Or, The micro generator described in step S3 is replaced by an axial structure of a permanent magnet generator with the rotor coil and the engine pulley being integrated, that is, a plurality of axial tooth grooves are arranged on one side of the inner step of the engine pulley, thereby constituting the core of the rotor coil of the micro generator; the rotor coil of the micro generator is constituted after embedding the coil on the core; the permanent magnet stator is arranged in parallel on the axial outer side of the rotor coil of the micro generator; the permanent magnet stator is fixed on the outer side of the crankcase or the base through the foot, and does not rotate with the crankshaft.

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