Device for measuring torque of rear drive rotating shaft of tractor

Abstract

A device for measuring the torque of a rotating shaft of a rear driving wheel of a tractor is composed of a magnetic ring, a Hall sensor and a torque measuring ECU. 32 permanent magnets are uniformly arranged in a circular ring in an annular manner, two magnetic rings are respectively sleeved on the left rear driving wheel rotating shaft and the right rear driving wheel rotating shaft, one magnetic ring is close to a gearbox, and the other magnetic ring is close to a wheel hub flange; and the four Hall sensors are fixed on the rear axle shell, and the sensing end surfaces of the Hall sensors are 2-10mm away from the magnetic rings. An output pin of the Hall sensor is electrically connected with a signal input pin of a PLL chip of the torque measurement ECU, a phase difference output pin of the PLL chip is electrically connected with a GPIO pin of the single-chip microcomputer, a torque value is calculated according to a formula (1) by measuring the duty ratio of a high level in a phase difference square wave signal, and the single-chip microcomputer issues torque information and can respond to a CAN bus and output the torque value. According to the invention, slip ring friction in the torque measurement process is avoided, the cost of torque measurement is reduced, and digitization of the tractor is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of agricultural machinery equipment, and in particular relates to a measuring device for a tractor. Background Art

[0002] Tractors are the mainstay of agricultural machinery and the main power machinery for tilling, sowing and spraying. Traction is the main technical indicator of tractors. Usually, only the maximum traction is tested at the factory. Inside the tractor, the torque of the rear drive wheel shaft is the most directly related to traction. At the work site, the actual traction is often complex and changeable. If the real-time traction is known, the fullness of the power can be understood, which helps to judge whether the selected tractor is reasonable and whether the gear configuration of the gearbox is reasonable. The monitoring of the rear drive shaft torque has long attracted the attention of researchers. For example, the paper "Test Method for the Torque of the Driving Wheel of the Tieniu-55 Tractor" (Journal of Jilin Agricultural University, 1987) pastes a resistance strain gauge in the principal stress direction (45° to the axis) on the surface of the rear drive wheel shaft to construct an electric bridge, and measures the relationship between torque and strain through experiments. This method has also become a commonly used method for measuring the torque of the driving wheel shaft and power output shaft. Although the strain gauge is low in cost, it is difficult for ordinary users to master the strain gauge pasting technology. In addition, because the shaft in the measurement is in a rotating state, a slip ring must be configured to realize the output of the signal, which not only increases the cost of the measurement, but also the inevitable wear makes the life of the slip ring relatively limited, and also reduces the measurement accuracy. The main gearbox of the tractor is on the longitudinal axis. The rear drive wheel shaft needs to pass through a long space to transmit power to the rear wheel, which makes the rear drive shaft longer. Its length is between 450mm and 550mm. The relative rotation angle between its two end faces is proportional to the torque, and the maximum relative rotation angle can reach 4°. It can be seen that this more significant relative rotation angle between the end faces can be fully utilized to construct a low-cost non-contact torque sensing device, providing a new method for measuring the torque of the rear drive wheel shaft of the tractor. Summary of the invention

[0003] In order to overcome the defects of high cost and short life of the existing method for measuring the torque of the rear drive wheel shaft of the tractor, the present invention provides a technical solution for non-contact torque measurement, that is, utilizing the long characteristic of the rear drive wheel shaft of the tractor to collect the relative rotation angles of its two end faces to realize non-contact torque measurement with low cost and long life.

[0004] The technical solution adopted by the present invention to solve its technical problem is: the device for measuring the torque of the rear driving wheel shaft of the tractor is composed of the first to fourth magnetic rings, the first to fourth Hall sensors and the torque measurement ECU. The first magnetic ring is sleeved on the gearbox side of the left rear driving wheel shaft, the first Hall sensor is in the radial direction of the first magnetic ring, and the sensing end face of the first Hall sensor is 2 to 10 mm away from the surface of the first magnetic ring; the second magnetic ring is sleeved on the left hub flange side of the left rear driving wheel shaft, the second Hall sensor is in the radial direction of the second magnetic ring, and the sensing end face of the second Hall sensor is 2 to 10 mm away from the surface of the second magnetic ring; the third magnetic ring is sleeved on the gearbox side of the right rear driving wheel shaft, the third Hall sensor is in the radial direction of the third magnetic ring, and the sensing end face of the third Hall sensor is 2 to 10 mm away from the surface of the third magnetic ring; the fourth magnetic ring is sleeved on the right hub flange of the right rear driving wheel shaft On the side, the fourth Hall sensor is in the radial direction of the fourth magnetic ring, and the inductive end face of the fourth Hall sensor is 2~10mm away from the surface of the fourth magnetic ring; the first to fourth magnetic rings are each composed of 32 permanent magnets arranged evenly in a circular ring in a ring manner, and the N pole of each permanent magnet is attracted to the surface of the rear drive wheel shaft, and the S pole faces the Hall sensor; the first to fourth Hall sensors are clamped and fixed to the rear axle housing by nuts; when the tractor moves, that is, the left and right rear drive wheel shafts rotate, the first to fourth Hall sensors can output square waves, there is a phase difference between the output of the second Hall sensor and the first Hall sensor, and there is a phase difference between the output of the fourth Hall sensor and the third Hall sensor.

[0005] The torque measurement ECU consists of two PLL chips, a single-chip microcomputer, a CAN protocol chip, a CAN driver chip and an NBIOT wireless module, wherein the single-chip microcomputer has its own WiFi antenna. The XA and XB pin terminals J1 of the first PLL chip are electrically connected to the signal output pins of the first Hall sensor and the second Hall sensor respectively, and the XA and XB pin terminals J2 of the second PLL chip are electrically connected to the signal output pins of the third Hall sensor and the fourth Hall sensor; the phase difference output PHASE COMPOUT pin of the first PLL chip is electrically connected in series with the resistor R1 and the VCOIN pin of the PLL chip, and its VCOOUT pin is electrically connected to its XB pin; the phase difference output PHASE COMPOUT pin of the second PLL chip is electrically connected in series with the resistor R2 and the VCOIN pin of the PLL chip, and its VCOOUT pin is electrically connected to its XB pin; the phase difference output pins of the first PLL chip and the second PLL chip are electrically connected to a GPIO pin of the single-chip microcomputer respectively, and the single-chip microcomputer captures the high and low level time of these two GPIO pins, then the torque calculation formula of any rear drive wheel shaft is: (1) In the formula, T is the torque, t H, t L , are respectively the high level time and low level time of the phase difference square wave when there is load, t H0 , t L0 , are respectively the high level time and low level time of the phase difference square wave at no-load, and k is the coefficient converted from duty cycle to torque, which is measured during experimental calibration.

[0006] The SPI interface of the microcontroller is electrically connected to the SPI interface of the CAN protocol chip, the CAN protocol chip is electrically connected to the TXD and RXD pins of the CAN driver chip, the CANH and CANL pins of the CAN driver chip are connected to the tractor's CAN bus through terminal J3, and the UART2 pin of the microcontroller is electrically connected to the UART pin of the NBIOT wireless module to replace WIFI and publish data to the MQTT server.

[0007] After the torque measurement ECU is powered on, it generates CAN objects, USART objects, GPIO objects, timer objects, MQTT objects and WiFi objects. When the software starts, if there is a WiFi signal, it connects to the MQTT server. Otherwise, it establishes communication with the NBIOT module through the USART object and connects to the MQTT server. Set the signal transition interrupt to capture the rising edge and the falling edge. In the interrupt program, if it is triggered by the rising edge, calculate the low level time, otherwise calculate the high level time, and calculate the torque according to formula (1). Whenever a torque calculation is completed, the MQTT object publishes data to the MQTT server. As long as the "torque" message is subscribed on the mobile phone, the monitoring personnel can see the real-time torque value of "torque" on the mobile phone. When the CAN object receives a data request, it can send the latest torque data to the CAN request target.

[0008] The beneficial effect of the present invention is that the torque measurement of the rear drive wheel shaft of the tractor is completed by using the non-contact magnetoelectric technology, which reduces the cost of torque measurement and contributes to the digitalization process of the tractor. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention is further described below with reference to the accompanying drawings and embodiments: Figure 1 It is an embodiment in which four magnetic rings and four Hall sensors are arranged in the rear axle of a tractor; Figure 2 yes Figure 1 A top view of an embodiment; Figure 3 It is an embodiment of the torque measurement ECU circuit schematic; Figure 4 is an embodiment of the software flow of the torque measurement ECU; In the figure, 1, left wheel hub flange, 2, left rear drive wheel shaft, 3, second magnetic ring, 4, second Hall sensor, 5, left rear axle housing, 6, first magnetic ring, 7, first Hall sensor, 8, gearbox, 9, right rear drive wheel shaft, 10, third Hall sensor, 11, third magnetic ring, 12, right rear axle housing, 13, fourth Hall sensor, 14, fourth magnetic ring, 15, right wheel hub flange, 16, first CD4046, 17, terminal J2, 18, second CD4046, 19, terminal J1, 20, ESP32 module, 21, BC260Y, 22, XL2515, 23, XL1050, 24, terminal J3. DETAILED DESCRIPTION

[0010] Figure 1 and Figure 2 The invention relates to an embodiment in which four magnetic rings (6, 3, 11, 14) and four Hall sensors (7, 4, 10, 13) are arranged in a rear axle of a tractor, wherein the first magnetic ring (6) is sleeved on the gearbox (8) side of the left rear drive wheel shaft (2), the first Hall sensor (7) is in the radial direction of the first magnetic ring (6), and the sensing end face of the first Hall sensor (7) is 2 to 10 mm away from the surface of the first magnetic ring (6); the second magnetic ring (3) is sleeved on the left hub flange (1 ) side, the second Hall sensor (4) is in the radial direction of the second magnetic ring (3), and the sensing end face of the second Hall sensor (4) is 2 to 10 mm away from the surface of the second magnetic ring (3); the third magnetic ring (11) is sleeved on the gearbox (8) side of the right rear drive wheel shaft (9), the third Hall sensor (10) is in the radial direction of the third magnetic ring (11), and the sensing end face of the third Hall sensor (10) is 2 to 10 mm away from the surface of the third magnetic ring (11); the fourth magnetic ring (14) is sleeved on the right On the right wheel hub flange (15) side of the rear drive wheel shaft (9), the fourth Hall sensor (13) is in the radial direction of the fourth magnetic ring (14), and the sensing end face of the fourth Hall sensor (13) is 2 to 10 mm away from the surface of the fourth magnetic ring (14); the first to fourth magnetic rings (6, 3, 11, 14) each consist of 32 permanent magnets arranged evenly in a circular ring in a circular manner, and the N pole of each permanent magnet is attracted to the surface of the rear drive wheel shaft (2, 9), and the S pole faces the Hall sensor (7, 4,10,13); the first to fourth Hall sensors (7,4,10,13) are all clamped and fixed to the rear axle housing (5,12) by nuts; when the tractor moves, that is, when the left and right rear drive wheel shafts (2,9) rotate, the first to fourth Hall sensors (7,4,10,13) can all output square waves, the outputs of the second Hall sensor (4) and the first Hall sensor (7) have a phase difference, and the outputs of the fourth Hall sensor (13) and the third Hall sensor (10) have a phase difference.

[0011] Figure 3 The invention is an embodiment of a torque measurement ECU circuit schematic diagram. The torque measurement ECU is composed of two CD4046 (16, 18), an ESP32 module (20), an XL2515 (22), an XL1050 (23) and a BC260Y (21), wherein the ESP32 module (20) has a built-in WiFi antenna. The XA and XB pin terminals J1 (19) of the first CD4046 (16) are electrically connected to the signal output pins of the first Hall sensor (7) and the second Hall sensor (4), respectively; the XA and XB pin terminals J2 (17) of the second CD4046 (18) are electrically connected to the signal output pins of the third Hall sensor (10) and the fourth Hall sensor (13); the phase difference output PHASECOMPOUT pin of the first CD4046 (16) is electrically connected in series with the resistor R1 and the VCOIN pin of the CD4046 (16); the VCOOUT pin of the CD4046 (16) is electrically connected to its XB pin; the phase difference output PHASECOMPOUT pin of the second CD4046 (18) is electrically connected to the resistor R1 and the VCOIN pin of the CD4046 (16), respectively; the VCOOUT pin of the CD4046 (16) is electrically connected to its XB pin; the phase difference output PHASECOMPOUT pin of the second CD4046 (18) is electrically connected to the VCOIN pin of the CD4046 (16), respectively. The COMPOUT pin is electrically connected in series with the resistor R2 and the VCOIN pin of the CD4046 (18), and the VCOOUT pin of the CD4046 (18) is electrically connected to the XB pin of the CD4046 (16). The phase difference output pins of the first CD4046 (16) and the second CD4046 (18) are electrically connected to the GPIO32 and GPIO33 pins of the ESP32 module (20), respectively, and the ESP32 module (20) captures the high level and low level time of the two GPIO pins. The SPI interface of the ESP32 module (20) is electrically connected to the SPI interface of the XL2515 (22), and the XL2515 (22) is electrically connected to the TXD and RXD pins of the XL1050 (23). The CANH and CANL pins of the XL1050 (23) are connected to the CAN bus of the tractor through the terminal J3 (24), and the UART2 pin of the ESP32 module (20) is electrically connected to the UART pin of the BC260Y (21).

[0012] Figure 4The invention is an embodiment of the software flow of the torque measurement ECU. After the torque measurement ECU is powered on, it generates XL2515 object, USART object, GPIO object, timer object, MQTT object and WiFi object; when the software is started, if there is a WiFi signal, it connects to the MQTT server, otherwise, it establishes communication with BC260Y (21) through the USART object and connects to the MQTT server; sets the signal transition interrupt to capture the rising edge and the falling edge; in the interrupt program, if it is triggered by the rising edge, it calculates the low level time, otherwise, it calculates the high level time, and calculates the torque according to formula (1); whenever a torque calculation is completed, the MQTT object publishes data to the MQTT server; as long as the "torque" message is subscribed on the mobile phone, the monitoring personnel can see the real-time torque value on the mobile phone; when the CAN object receives the data request, it can send the latest torque data to the CAN request target.

Claims

1. A device for measuring the torque of a rear drive wheel shaft of a tractor, comprising first to fourth magnetic rings, first to fourth Hall sensors and a torque measurement ECU, wherein: The first magnetic ring is sleeved on the gearbox side of the left rear drive wheel shaft, the first Hall sensor is in the radial direction of the first magnetic ring, and the sensing end face of the first Hall sensor is 2~10mm away from the surface of the first magnetic ring; the second magnetic ring is sleeved on the left hub flange side of the left rear drive wheel shaft, the second Hall sensor is in the radial direction of the second magnetic ring, and the sensing end face of the second Hall sensor is 2~10mm away from the surface of the second magnetic ring; the third magnetic ring is sleeved on the gearbox side of the right rear drive wheel shaft, the third Hall sensor is in the radial direction of the third magnetic ring, and the sensing end face of the second Hall sensor is 2~10mm away from the surface of the second magnetic ring. The inductive end face of the sensor is 2~10mm away from the surface of the third magnetic ring; the fourth magnetic ring is sleeved on the right hub flange side of the right rear drive wheel shaft, the fourth Hall sensor is in the radial direction of the fourth magnetic ring, and the inductive end face of the fourth Hall sensor is 2~10mm away from the surface of the fourth magnetic ring; the first to fourth magnetic rings are each composed of 32 permanent magnets arranged evenly in a circular ring in a ring manner, the N pole of each permanent magnet is attracted to the surface of the rear drive wheel shaft, and the S pole faces the Hall sensor; the first to fourth Hall sensors are clamped and fixed to the rear axle housing by nuts.

2. The device for measuring the torque of the rear drive wheel shaft of a tractor according to claim 1, characterized in that: The XA and XB pin terminals J1 of the first PLL chip are electrically connected to the signal output pins of the first Hall sensor and the second Hall sensor respectively, and the XA and XB pin terminals J2 of the second PLL chip are electrically connected to the signal output pins of the third Hall sensor and the fourth Hall sensor; the phase difference output PHASE COMPOUT pin of the first PLL chip is electrically connected in series with the resistor R1 and the VCOIN pin of the PLL chip, and its VCOOUT pin is electrically connected to its XB pin; the phase difference output PHASECOMPOUT pin of the second PLL chip is electrically connected in series with the resistor R2 and the VCOIN pin of the PLL chip, and its VCOOUT pin is electrically connected to its XB pin; the phase difference output pins of the first PLL chip and the second PLL chip are electrically connected to a GPIO pin of the single-chip microcomputer respectively, and the single-chip microcomputer captures the high level and low level time of these two GPIO pins, then the torque calculation formula of any rear drive wheel shaft is: ； (1) In the formula, T is the torque, t H , t L , are respectively the high level time and low level time of the phase difference square wave when there is load, t H0 , t L0 , are respectively the high level time and low level time of the phase difference square wave at no-load, k is the coefficient converted from duty cycle to torque, which is measured during experimental calibration; the SPI interface of the microcontroller is electrically connected to the SPI interface of the CAN protocol chip, the CAN protocol chip is electrically connected to the TXD and RXD pins of the CAN driver chip, the CANH and CANL pins of the CAN driver chip are connected to the tractor's CAN bus through terminal J3, and the UART2 pin of the microcontroller is electrically connected to the UART pin of the NBIOT wireless module.

3. The device for measuring the torque of the rear drive wheel shaft of a tractor according to claim 1, characterized in that: After the torque measurement ECU is powered on, it generates CAN objects, USART objects, GPIO objects, timer objects, MQTT objects and WiFi objects. When the software starts, if there is a WiFi signal, it connects to the MQTT server. Otherwise, it establishes communication with the NBIOT module through the USART object and connects to the MQTT server. Set the signal transition interrupt to capture the rising and falling edges. In the interrupt program, if it is triggered by the rising edge, calculate the low level time, otherwise calculate the high level time, and calculate the torque according to formula (1). Whenever a torque calculation is completed, the MQTT object publishes data to the MQTT server. As long as the "Torque" message is subscribed on the mobile phone, the monitoring personnel can see the real-time torque value on the mobile phone; when the CAN object receives the data request, the latest torque data can be sent to the CAN request target.

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