Excavator sensor measurement method and data detailed explanation
Posted: Mar 26th, '25, 04:30
In the complex operation system of modern excavators, sensors play a vital role. They are like the "sensory nerves" of equipment, monitoring the operation status of various key parts at all times, and providing indispensable data support for the efficient and stable operation of excavators. In-depth understanding of the measurement methods and corresponding data meaning of these sensors is of decisive significance for excavator owners and maintenance personnel to quickly diagnose equipment problems, ensure safe production, and improve work efficiency. Below, we will analyze all kinds of common sensors for you.
Pressure sensors: A precise "stethoscope" for hydraulic systems
Measurement method
The pressure sensor is usually installed in the key pipeline nodes of the hydraulic system, and its core working principle is to convert the pressure signal of the hydraulic oil into an electrical signal for easy detection. In the actual measurement, the most commonly used tool is a multimeter. Taking the measurement of the pressure sensor of the main oil circuit as an example, the multimeter must be accurately adjusted to the DC voltage.
Then, carefully disconnect the sensor plug, connect the black pen of the multimeter to the ground end of the plug, and connect the red pen to the signal output end. After completing the above operations, start the engine and put the hydraulic system into operation. At this time, the voltage value displayed by the multimeter is not a direct pressure value, but a signal value that has a specific correspondence with the actual pressure of the system. Maintenance personnel need to be based on the calibration curve of the sensor, after accurate conversion, in order to get the real pressure value of the system. In the whole operation process, the choice of the range of the multimeter is particularly critical.
If the range is too small, when the system pressure exceeds the range, it is easy to cause damage to the multimeter. However, if the range is too large, the measurement accuracy will be greatly reduced, and accurate data cannot be obtained. For example, in a maintenance of a brand of excavator, the maintenance personnel chose too large multimeter range due to negligence, and the voltage value measured by the error is very large, which makes the judgment of the pressure of the hydraulic system seriously wrong, and greatly delays the troubleshooting progress. It can be seen that strict adherence to the standard process and correct selection of measuring tools and parameters are the basis for ensuring accurate and reliable measurement data of pressure sensors.
Data range
The data range of pressure sensors in different positions is obviously different. The measuring range of the main oil pressure sensor is generally in the range of 0-40MPa. For a common type of excavator, its main pressure is usually in the range of 20-40MPa under normal working conditions. Once the sensor output data deviates from this normal range, it often means that the key components of the hydraulic system, such as hydraulic pumps, relief valves, etc., may be faulty. For example, when the main oil pressure sensor display value continues to be lower than 20MPa, it is most likely that the plunger inside the hydraulic pump has suffered serious wear due to long-term high-intensity work, resulting in a significant reduction in the volumetric efficiency of the hydraulic pump, unable to generate enough pressure to drive the normal operation of the hydraulic system. In this case, maintenance personnel need to disassemble the hydraulic pump in time, carefully inspect the worn plunger and other parts, and replace them if necessary to restore the normal working performance of the hydraulic pump. Look at the pilot oil pressure sensor, its normal working pressure range is generally 2-5MPa.
If the sensor data is abnormal, the control function of the pilot system may fail, which seriously affects the accurate execution of various actions of the excavator. For example, when the value of the pilot pressure sensor is higher than 5MPa, it is likely that the spool of the pilot relief valve is stuck by a foreign body and remains in the closed position, so that the pressure cannot be released normally and continues to rise. At this time, the maintenance personnel should quickly conduct a comprehensive cleaning of the pilot relief valve, check whether the spool activity is smooth, and debug as needed to ensure that the pilot relief valve can restore the normal pressure control function and ensure the stable operation of the pilot system.
Temperature sensor: "temperature monitor" for device operation
Measurement method
The temperature sensor is widely distributed on the excavator, which is commonly found in the engine coolant pipeline, hydraulic fuel tank, transmission oil pan and other parts, and is mainly used for real-time measurement of the temperature of various liquids. In the measurement process, in order to ensure the accuracy of the data, it is usually assisted by infrared thermometers for verification. Taking the measuring engine coolant temperature sensor as an example, the infrared thermometer is first used to accurately align its measuring probe to the flow area of the engine coolant to measure the actual temperature of the coolant. At the same time, use a multimeter to measure the resistance value of the coolant temperature sensor. Since most temperature sensors use negative temperature coefficient thermistors, that is, when the temperature rises, the resistance value will decrease. The maintenance personnel need to compare the resistance value measured by the multimeter with the temperature-resistance characteristic curve of the sensor, and then carefully compare the temperature value corresponding to the resistance value.
Finally, the temperature value converted by the resistance value is compared with the actual temperature value measured by the infrared thermometer to judge whether the working state of the temperature sensor is normal. In actual operation, it is important to ensure that the measuring part of the infrared thermometer is accurate and in full contact with the coolant. Otherwise, once the measurement position deviation, it may lead to serious inaccurate measurement results. During the operation of an excavator, the operator suddenly received an alarm warning that the coolant temperature was too high. However, when using an infrared thermometer to measure the actual temperature of the coolant, it shows normal. After careful investigation, it was found that when the operator used the infrared thermometer, the measuring probe was not accurately aligned with the coolant flow area, resulting in an error in the measurement results, and almost made a wrong judgment on the fault, affecting the normal operation of the equipment.
Data range
The normal operating temperature range of the engine coolant temperature sensor is generally 80-95 ℃. Once this range is exceeded, the engine's combustion efficiency and power output will be significantly affected. When the coolant temperature is higher than 95 ° C for a long time, it is most likely that the engine's cooling system has failed. For example, the heat sink of the radiator may be exposed to the harsh environment for a long time, accumulating a lot of dust and debris, resulting in a significant decrease in heat dissipation efficiency; Or there is a problem with the driving device of the cooling fan, so that the fan speed is not enough to effectively take away the heat generated by the engine.
In this case, maintenance personnel need to comprehensively clean the radiator in time to ensure smooth ventilation of the heat sink; At the same time, check the cooling fan drive motor, belt and other parts, repair or replace the faulty parts, in order to restore the normal working efficiency of the cooling system. Look at the hydraulic oil temperature sensor, its normal operating temperature range is 40-80 ° C. When the oil temperature is too high, the oil viscosity will decrease significantly, which will greatly increase the leakage risk of the hydraulic system, and reduce the overall efficiency of the system; When the oil temperature is too low, the oil viscosity increases, which will cause the hydraulic pump to suck oil difficult, not only increase energy consumption, but also may cause additional wear to the pump body. If the hydraulic oil temperature is below 40 ° C, the operator can heat the hydraulic oil by starting the preheating device that comes with the equipment; Or let the equipment run in the no-load state for a period of time, using the heat generated by the operation of the equipment itself, so that the oil temperature gradually rises to the normal range to ensure that the hydraulic system can work normally and stably.
Speed sensor: the "rhythm control" of equipment operation
Measurement method
The speed sensor is mainly responsible for measuring key parameters such as engine crankshaft speed and pump speed to ensure the coordinated operation of equipment components. Taking measuring engine speed sensor as an example, the common engine speed sensor has two types: electromagnetic induction type and Hall type. For electromagnetic induction speed sensor, it is necessary to use oscilloscope to measure its output signal waveform. In the operation, the triggering conditions and time parameters of the oscilloscope must be set correctly, only in this way can the signal waveform output by the sensor be accurately captured. By calculating the number of pulses in the signal waveform per unit time, combined with the number of teeth of the sensor itself, the speed of the starting motor can be accurately calculated.
For the Hall-type speed sensor, the output voltage pulse can be measured by a multimeter. The specific operation is to adjust the multimeter to the appropriate voltage measurement gear, measure the voltage pulse signal output by the sensor, and then obtain the engine speed after conversion according to the corresponding relationship between the pulse frequency and the speed. In the actual measurement process, the accuracy of oscilloscope parameter setting is very important to obtain accurate speed data. For example, when a maintenance personnel is measuring the speed sensor of an excavator engine, due to the improper setting of oscilloscope trigger conditions and time parameters, the oscilloscope display waveform is disorganized, and the speed cannot be accurately calculated. After repeated debugging of oscilloscope parameters, the clear and accurate signal waveform is finally obtained, so as to calculate the starting motor speed successfully.
Data range
The normal working range of the engine speed sensor will vary depending on the type of excavator and the actual working conditions. Generally speaking, in the no-load state, the engine speed is usually 1000-1500 RPM; In full load operation, the speed is usually increased to about 1500-2200 RPM. The data of the pump speed sensor needs to be matched with the engine speed and the overall operating requirements of the hydraulic system to ensure that the hydraulic oil can steadily output the appropriate flow and pressure. If the engine speed sensor is consistently below 1500 RPM at full load, it is likely that the engine's fuel supply system has failed.
For example, the fuel injection nozzle may be due to long-term use, internal carbon accumulation is serious, resulting in poor fuel injection; Or the pump pressure is insufficient to provide enough fuel to the engine. These problems will directly affect the power output of the engine, which will lead to a decrease in speed. In this case, maintenance personnel need to conduct a comprehensive inspection of the fuel supply system in time, clean the fuel injector, overhaul the oil pump and other components, to ensure that the fuel can be normally supplied and the normal speed of the engine can be restored. If the data of the pump speed sensor and the engine speed do not match, it may cause the hydraulic system pressure instability, mining weakness and other phenomena. At this time, maintenance personnel need to focus on checking the transmission device of the pump, to see if there are problems such as loose belts and gear wear, and to repair or replace the damaged parts in time to ensure that the pump speed is coordinated with the engine speed and maintain the stable operation of the hydraulic system.
Position sensor: "precise locator" of device motion
Measurement method
Position sensors are mainly used in excavators to monitor the position changes of working devices such as boom, bucket rod and bucket in real time to ensure accurate execution of excavation operations. Taking the measuring boom cylinder position sensor as an example, most of these sensors are linear displacement sensors, and their working principle is to accurately determine the actual position of the boom by measuring the extension or retract length of the cylinder piston rod. In actual measurement, a multimeter is used to measure the ratio of the sensor output voltage to the input voltage, and there is a strict linear relationship between this ratio and the displacement of the piston rod. By calculating this ratio, the maintenance personnel can accurately obtain the position information of the mobilization arm.
In addition, some advanced position sensors have the CAN bus communication function, and the operator can read the relevant data such as the position of the boom directly through the display screen of the device, which greatly improves the convenience and accuracy of data acquisition. When using a multimeter to measure a linear displacement sensor, ensure that the multimeter pen is in close and good contact with the sensor terminal. Otherwise, once there is poor contact, it will lead to a substantial increase in the measurement error, affecting the accurate judgment of the boom position. There was once an excavator in the process of operation, the operator found that the lifting position of the boom was not accurate, after careful inspection, it turned out that the contact between the multimeter pen and the sensor terminal was loose, resulting in deviation of the measurement data. After the maintenance personnel reconnects the marker to ensure good contact, the measurement of the boom position returns to normal, and the operation accuracy of the equipment is also guaranteed.
Data range
The data range of the boom position sensor is determined according to the maximum lifting height designed by the excavator. For example, the maximum lifting height of a certain type of excavator arm is 6 meters, and the corresponding position sensor output signal range may be 0-5V. When the boom rises to the highest position, the sensor output signal is close to 5V; When the boom is lowered to the lowest position, the output signal is close to 0V. The working principle and data range determination of the bucket rod and bucket position sensor are similar to that of the boom position sensor, and their data range is also closely related to the maximum stroke of the respective working device, mainly for precise control of the mining action to ensure that the operation reaches the highest accuracy requirements. If the output signal of the boom position sensor is much lower than 5V when the boom is raised to the highest position, it is likely that some components inside the sensor are damaged, resulting in an abnormal output signal. At this time, maintenance personnel need to replace the sensor in time to ensure the accuracy of the boom position measurement. Otherwise, in the actual operation process, it may cause safety accidents such as inaccurate digging depth and collision with surrounding objects due to the wrong judgment of the boom position, which will seriously affect the construction.
In the daily maintenance and troubleshooting of excavators, mastering the measurement methods of various sensors and accurately interpreting their data ranges is the key to quickly and accurately judge the operating status of excavators. Only in this way can the potential problems of the equipment be found in time, effective maintenance measures be taken to ensure that the excavator is always in a good state of operation and provide a solid and powerful guarantee for the smooth advancement of the project construction.
Pressure sensors: A precise "stethoscope" for hydraulic systems
Measurement method
The pressure sensor is usually installed in the key pipeline nodes of the hydraulic system, and its core working principle is to convert the pressure signal of the hydraulic oil into an electrical signal for easy detection. In the actual measurement, the most commonly used tool is a multimeter. Taking the measurement of the pressure sensor of the main oil circuit as an example, the multimeter must be accurately adjusted to the DC voltage.
Then, carefully disconnect the sensor plug, connect the black pen of the multimeter to the ground end of the plug, and connect the red pen to the signal output end. After completing the above operations, start the engine and put the hydraulic system into operation. At this time, the voltage value displayed by the multimeter is not a direct pressure value, but a signal value that has a specific correspondence with the actual pressure of the system. Maintenance personnel need to be based on the calibration curve of the sensor, after accurate conversion, in order to get the real pressure value of the system. In the whole operation process, the choice of the range of the multimeter is particularly critical.
If the range is too small, when the system pressure exceeds the range, it is easy to cause damage to the multimeter. However, if the range is too large, the measurement accuracy will be greatly reduced, and accurate data cannot be obtained. For example, in a maintenance of a brand of excavator, the maintenance personnel chose too large multimeter range due to negligence, and the voltage value measured by the error is very large, which makes the judgment of the pressure of the hydraulic system seriously wrong, and greatly delays the troubleshooting progress. It can be seen that strict adherence to the standard process and correct selection of measuring tools and parameters are the basis for ensuring accurate and reliable measurement data of pressure sensors.
Data range
The data range of pressure sensors in different positions is obviously different. The measuring range of the main oil pressure sensor is generally in the range of 0-40MPa. For a common type of excavator, its main pressure is usually in the range of 20-40MPa under normal working conditions. Once the sensor output data deviates from this normal range, it often means that the key components of the hydraulic system, such as hydraulic pumps, relief valves, etc., may be faulty. For example, when the main oil pressure sensor display value continues to be lower than 20MPa, it is most likely that the plunger inside the hydraulic pump has suffered serious wear due to long-term high-intensity work, resulting in a significant reduction in the volumetric efficiency of the hydraulic pump, unable to generate enough pressure to drive the normal operation of the hydraulic system. In this case, maintenance personnel need to disassemble the hydraulic pump in time, carefully inspect the worn plunger and other parts, and replace them if necessary to restore the normal working performance of the hydraulic pump. Look at the pilot oil pressure sensor, its normal working pressure range is generally 2-5MPa.
If the sensor data is abnormal, the control function of the pilot system may fail, which seriously affects the accurate execution of various actions of the excavator. For example, when the value of the pilot pressure sensor is higher than 5MPa, it is likely that the spool of the pilot relief valve is stuck by a foreign body and remains in the closed position, so that the pressure cannot be released normally and continues to rise. At this time, the maintenance personnel should quickly conduct a comprehensive cleaning of the pilot relief valve, check whether the spool activity is smooth, and debug as needed to ensure that the pilot relief valve can restore the normal pressure control function and ensure the stable operation of the pilot system.
Temperature sensor: "temperature monitor" for device operation
Measurement method
The temperature sensor is widely distributed on the excavator, which is commonly found in the engine coolant pipeline, hydraulic fuel tank, transmission oil pan and other parts, and is mainly used for real-time measurement of the temperature of various liquids. In the measurement process, in order to ensure the accuracy of the data, it is usually assisted by infrared thermometers for verification. Taking the measuring engine coolant temperature sensor as an example, the infrared thermometer is first used to accurately align its measuring probe to the flow area of the engine coolant to measure the actual temperature of the coolant. At the same time, use a multimeter to measure the resistance value of the coolant temperature sensor. Since most temperature sensors use negative temperature coefficient thermistors, that is, when the temperature rises, the resistance value will decrease. The maintenance personnel need to compare the resistance value measured by the multimeter with the temperature-resistance characteristic curve of the sensor, and then carefully compare the temperature value corresponding to the resistance value.
Finally, the temperature value converted by the resistance value is compared with the actual temperature value measured by the infrared thermometer to judge whether the working state of the temperature sensor is normal. In actual operation, it is important to ensure that the measuring part of the infrared thermometer is accurate and in full contact with the coolant. Otherwise, once the measurement position deviation, it may lead to serious inaccurate measurement results. During the operation of an excavator, the operator suddenly received an alarm warning that the coolant temperature was too high. However, when using an infrared thermometer to measure the actual temperature of the coolant, it shows normal. After careful investigation, it was found that when the operator used the infrared thermometer, the measuring probe was not accurately aligned with the coolant flow area, resulting in an error in the measurement results, and almost made a wrong judgment on the fault, affecting the normal operation of the equipment.
Data range
The normal operating temperature range of the engine coolant temperature sensor is generally 80-95 ℃. Once this range is exceeded, the engine's combustion efficiency and power output will be significantly affected. When the coolant temperature is higher than 95 ° C for a long time, it is most likely that the engine's cooling system has failed. For example, the heat sink of the radiator may be exposed to the harsh environment for a long time, accumulating a lot of dust and debris, resulting in a significant decrease in heat dissipation efficiency; Or there is a problem with the driving device of the cooling fan, so that the fan speed is not enough to effectively take away the heat generated by the engine.
In this case, maintenance personnel need to comprehensively clean the radiator in time to ensure smooth ventilation of the heat sink; At the same time, check the cooling fan drive motor, belt and other parts, repair or replace the faulty parts, in order to restore the normal working efficiency of the cooling system. Look at the hydraulic oil temperature sensor, its normal operating temperature range is 40-80 ° C. When the oil temperature is too high, the oil viscosity will decrease significantly, which will greatly increase the leakage risk of the hydraulic system, and reduce the overall efficiency of the system; When the oil temperature is too low, the oil viscosity increases, which will cause the hydraulic pump to suck oil difficult, not only increase energy consumption, but also may cause additional wear to the pump body. If the hydraulic oil temperature is below 40 ° C, the operator can heat the hydraulic oil by starting the preheating device that comes with the equipment; Or let the equipment run in the no-load state for a period of time, using the heat generated by the operation of the equipment itself, so that the oil temperature gradually rises to the normal range to ensure that the hydraulic system can work normally and stably.
Speed sensor: the "rhythm control" of equipment operation
Measurement method
The speed sensor is mainly responsible for measuring key parameters such as engine crankshaft speed and pump speed to ensure the coordinated operation of equipment components. Taking measuring engine speed sensor as an example, the common engine speed sensor has two types: electromagnetic induction type and Hall type. For electromagnetic induction speed sensor, it is necessary to use oscilloscope to measure its output signal waveform. In the operation, the triggering conditions and time parameters of the oscilloscope must be set correctly, only in this way can the signal waveform output by the sensor be accurately captured. By calculating the number of pulses in the signal waveform per unit time, combined with the number of teeth of the sensor itself, the speed of the starting motor can be accurately calculated.
For the Hall-type speed sensor, the output voltage pulse can be measured by a multimeter. The specific operation is to adjust the multimeter to the appropriate voltage measurement gear, measure the voltage pulse signal output by the sensor, and then obtain the engine speed after conversion according to the corresponding relationship between the pulse frequency and the speed. In the actual measurement process, the accuracy of oscilloscope parameter setting is very important to obtain accurate speed data. For example, when a maintenance personnel is measuring the speed sensor of an excavator engine, due to the improper setting of oscilloscope trigger conditions and time parameters, the oscilloscope display waveform is disorganized, and the speed cannot be accurately calculated. After repeated debugging of oscilloscope parameters, the clear and accurate signal waveform is finally obtained, so as to calculate the starting motor speed successfully.
Data range
The normal working range of the engine speed sensor will vary depending on the type of excavator and the actual working conditions. Generally speaking, in the no-load state, the engine speed is usually 1000-1500 RPM; In full load operation, the speed is usually increased to about 1500-2200 RPM. The data of the pump speed sensor needs to be matched with the engine speed and the overall operating requirements of the hydraulic system to ensure that the hydraulic oil can steadily output the appropriate flow and pressure. If the engine speed sensor is consistently below 1500 RPM at full load, it is likely that the engine's fuel supply system has failed.
For example, the fuel injection nozzle may be due to long-term use, internal carbon accumulation is serious, resulting in poor fuel injection; Or the pump pressure is insufficient to provide enough fuel to the engine. These problems will directly affect the power output of the engine, which will lead to a decrease in speed. In this case, maintenance personnel need to conduct a comprehensive inspection of the fuel supply system in time, clean the fuel injector, overhaul the oil pump and other components, to ensure that the fuel can be normally supplied and the normal speed of the engine can be restored. If the data of the pump speed sensor and the engine speed do not match, it may cause the hydraulic system pressure instability, mining weakness and other phenomena. At this time, maintenance personnel need to focus on checking the transmission device of the pump, to see if there are problems such as loose belts and gear wear, and to repair or replace the damaged parts in time to ensure that the pump speed is coordinated with the engine speed and maintain the stable operation of the hydraulic system.
Position sensor: "precise locator" of device motion
Measurement method
Position sensors are mainly used in excavators to monitor the position changes of working devices such as boom, bucket rod and bucket in real time to ensure accurate execution of excavation operations. Taking the measuring boom cylinder position sensor as an example, most of these sensors are linear displacement sensors, and their working principle is to accurately determine the actual position of the boom by measuring the extension or retract length of the cylinder piston rod. In actual measurement, a multimeter is used to measure the ratio of the sensor output voltage to the input voltage, and there is a strict linear relationship between this ratio and the displacement of the piston rod. By calculating this ratio, the maintenance personnel can accurately obtain the position information of the mobilization arm.
In addition, some advanced position sensors have the CAN bus communication function, and the operator can read the relevant data such as the position of the boom directly through the display screen of the device, which greatly improves the convenience and accuracy of data acquisition. When using a multimeter to measure a linear displacement sensor, ensure that the multimeter pen is in close and good contact with the sensor terminal. Otherwise, once there is poor contact, it will lead to a substantial increase in the measurement error, affecting the accurate judgment of the boom position. There was once an excavator in the process of operation, the operator found that the lifting position of the boom was not accurate, after careful inspection, it turned out that the contact between the multimeter pen and the sensor terminal was loose, resulting in deviation of the measurement data. After the maintenance personnel reconnects the marker to ensure good contact, the measurement of the boom position returns to normal, and the operation accuracy of the equipment is also guaranteed.
Data range
The data range of the boom position sensor is determined according to the maximum lifting height designed by the excavator. For example, the maximum lifting height of a certain type of excavator arm is 6 meters, and the corresponding position sensor output signal range may be 0-5V. When the boom rises to the highest position, the sensor output signal is close to 5V; When the boom is lowered to the lowest position, the output signal is close to 0V. The working principle and data range determination of the bucket rod and bucket position sensor are similar to that of the boom position sensor, and their data range is also closely related to the maximum stroke of the respective working device, mainly for precise control of the mining action to ensure that the operation reaches the highest accuracy requirements. If the output signal of the boom position sensor is much lower than 5V when the boom is raised to the highest position, it is likely that some components inside the sensor are damaged, resulting in an abnormal output signal. At this time, maintenance personnel need to replace the sensor in time to ensure the accuracy of the boom position measurement. Otherwise, in the actual operation process, it may cause safety accidents such as inaccurate digging depth and collision with surrounding objects due to the wrong judgment of the boom position, which will seriously affect the construction.
In the daily maintenance and troubleshooting of excavators, mastering the measurement methods of various sensors and accurately interpreting their data ranges is the key to quickly and accurately judge the operating status of excavators. Only in this way can the potential problems of the equipment be found in time, effective maintenance measures be taken to ensure that the excavator is always in a good state of operation and provide a solid and powerful guarantee for the smooth advancement of the project construction.