Load sensor system

Abstract

To prevent the generation of a load measurement error caused by a variation in the temperature inside a sensor, and reduce the waiting time required until measurement can be started.SOLUTION: A load sensor system estimates at S17 the time TP0 required until a variation in the temperature inside a load sensor unit after the start of power supply reaches a saturation point and becomes a stable temperature state, and notifies the time at S18. The load sensor system specifies the time TP0 from the internal temperature detected at the start of power supply or the gradient of the change in the temperature by using a temperature-saturation time table 61. The load sensor system starts counting the time TP0 and subsequently monitors the actual variation in the internal temperature, and when the variation reaches a stable state, notifies that the measurement can be performed before the time TP0 elapses. The load sensor system records actual result data of the variation in the internal temperature and reflects the data on the details of the temperature-saturation time table 61. When the load sensor system uses a plurality of load sensor units at the same time, it selects and notifies at S17 a predicted saturation time of a sensor in which the internal temperature saturates last.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a load sensor system that can be used for measuring the loading weight and the like in a vehicle.

Background Art

[0002] In a vehicle such as a tank truck, for example, it is necessary to measure the weight of the load. Also, in a large vehicle such as a truck, it is necessary to measure the weight of the load or the total weight of the vehicle in order to prevent overloading. The prior art of a measuring device that can be used in such applications is disclosed in, for example, Patent Document 1 and Patent Document 2.

[0003] Patent Document 1 discloses a technique for easily correcting the load sensor output even when it changes due to a temperature change and measuring the loading weight or the vehicle weight. Specifically, when the output change is small, correction processing is performed so that the same load calculation value as before the temperature change is output even for the latest sensor detection output. On the other hand, when the change is large, the latest sensor detection output is taken in without performing correction.

[0004] Patent Document 2 discloses a technique for accurately eliminating the measurement error due to a temperature change and improving the accuracy even when the change in the loading amount is small. Specifically, even when the change in the output of the load detection means or the change in the load calculation value is small, if an output change of a predetermined value or more has occurred in the behavior detection means, it is determined that the loading situation has changed, and the stored loading weight is updated to the latest calculation result based on the output of the load detection means.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Devices that detect loads on vehicle axles and other parts utilize sensors such as strain gauges to detect loads. These sensors are affected by temperature changes, which alter their physical properties and cause fluctuations in the output signal. Therefore, measures such as those described in Patent Documents 1 and 2 are necessary to prevent temperature changes from affecting the measured values.

[0007] Furthermore, when using a sensor unit in which a heat-generating electronic circuit and a sensor such as a strain gauge are integrated, it is necessary to consider not only changes in ambient temperature such as the outside air, but also changes in internal temperature caused by the heat generated by the sensor itself.

[0008] Therefore, when actually measuring loads, it is common practice to notify the user that measurement is possible only after a certain waiting period (e.g., 30 minutes) has elapsed since the power of the measuring device was turned on. In other words, after a certain waiting period has elapsed since the power of the measuring device was turned on, fluctuations in the internal temperature caused by the heat generated by the sensor itself are considered to have almost disappeared, thus reducing measurement errors caused by temperature fluctuations.

[0009] However, the time required from the power-on of the measuring device until the internal temperature fluctuations actually cease is not constant. For example, the required time tends to be longer when the ambient temperature around the sensor is relatively low. Therefore, even when measuring the load after the waiting time has elapsed, errors caused by internal temperature fluctuations may increase when the ambient temperature is low. Furthermore, if the waiting time is set to be long in order to reduce errors caused by internal temperature fluctuations, it is unavoidable that wasted time will increase because the load measurement cannot be started until the waiting time has elapsed even after the internal temperature fluctuations have actually ceased.

[0010] On the other hand, if the technology described in Patent Document 1 is adopted, any sensor output change below a predetermined value is simply attributed to a temperature change. Therefore, if this determination is incorrect, it is expected that the accuracy of load measurement will decrease.

[0011] Furthermore, when employing the technology described in Patent Document 2, temperature correction is performed after a predetermined time has elapsed since engine start / stop, which inevitably leads to wasted waiting time. If the waiting time is insufficient, errors will occur due to fluctuations in internal temperature. In addition, G-sensors and vehicle height sensors are required to detect the vehicle's behavior. Moreover, the outputs of these sensors fluctuate due to factors such as wind, which contributes to measurement errors.

[0012] The present invention has been made in view of the above circumstances, and its objective is to provide a load sensor system that can suppress the occurrence of load measurement errors caused by fluctuations in the internal temperature of the sensor, and shorten the waiting time until it is ready to start measuring. [Means for solving the problem]

[0013] The above objective according to the present invention is achieved by the following configuration.

[0014] In-vehicle device, A sensor unit mounted on the axle and connected to the on-board device, Equipped with, The sensor unit has the function of outputting a signal of the internal temperature detected inside the unit and a signal of the strain detected on the axle. The in-vehicle device has a function to estimate the time it takes for the internal temperature to saturate based on the signal output from the sensor unit, and to notify the estimated time. together , It has a temperature change monitoring unit that monitors changes in the measured internal temperature, The in-vehicle device, when the temperature change monitoring unit detects saturation of the measured internal temperature, permits notification of temperature saturation before the estimated time for the internal temperature is reached. Load sensor system. In-vehicle device, A sensor unit mounted on the axle and connected to the on-board device, Equipped with, The sensor unit has the function of outputting a signal of the internal temperature detected inside the unit and a signal of the strain detected on the axle. The in-vehicle device has a function to estimate the time it takes for the internal temperature to saturate based on the signal output from the sensor unit, and to notify the estimated time. For each of the multiple temperature values ​​corresponding to the aforementioned internal temperature, a temperature saturation table is provided that holds a constant for the time required until the internal temperature reaches the saturation temperature. Based on the measured internal temperature and the temperature saturation table, the time required for the internal temperature to reach the saturation temperature is estimated, The in-vehicle device has a temperature change monitoring unit that monitors changes in the measured internal temperature, The in-vehicle device updates the registered contents of the temperature saturation table, reflecting the actual time at which the temperature change monitoring unit detected the saturation of the measured internal temperature. Load sensor system. In-vehicle device, A sensor unit mounted on the axle and connected to the on-board device, Equipped with, The sensor unit has the function of outputting a signal of the internal temperature detected inside the unit and a signal of the strain detected on the axle. The in-vehicle device has a function to estimate the time it takes for the internal temperature to saturate based on the signal output from the sensor unit, and to notify the estimated time. Multiple sensor units, each positioned at a different location, are connected to the in-vehicle device. The in-vehicle device prioritizes notifying the latest time among the times when the internal temperature of each of the multiple sensor units becomes saturated. Load sensor system.

Advantages of the Invention

[0015] According to the load sensor system of the present invention, actual load measurement can be started after the internal temperature reaches saturation and temperature fluctuations hardly occur. Therefore, the occurrence of errors due to the temperature characteristics of the sensor is suppressed and the measurement accuracy is improved. In addition, the waiting time from when the device is powered on until load measurement starts can be shortened.

[0016] The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through the embodiments for carrying out the invention described below (hereinafter referred to as "embodiments") with reference to the accompanying drawings.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a block diagram showing the configuration of a load sensor system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a configuration example of one load sensor unit. [Figure 3] FIG. 3 is a front view showing a configuration example of a truck vehicle equipped with a load sensor system. [Figure 4] FIG. 4 is a right side view showing a configuration example of a truck vehicle equipped with a load sensor system. [Figure 5] FIG. 5 is a bottom view showing a configuration example of a truck vehicle equipped with a load sensor system. [Figure 6] Figure 6 is a graph showing the relationship between the internal temperature of the load sensor unit and the elapsed time since power-on. [Figure 7] Figure 7 is a schematic diagram showing an example of the configuration of a temperature-saturation time table. [Figure 8] Figure 8 is a graph showing an example of the characteristics of a temperature-saturation time table. [Figure 9] Figure 9 is a flowchart showing the preparatory steps taken before using the load sensor system. [Figure 10] Figure 10 is a flowchart showing a portion of the characteristic operation of the load sensor system. [Figure 11] Figure 11 is a flowchart showing a portion of the characteristic operation in a load sensor system. [Figure 12] Figure 12 is a flowchart showing an example of a table update process in a load sensor system. [Modes for carrying out the invention]

[0018] Specific embodiments of the present invention will be described below with reference to the figures.

[0019] <Configuration of the load sensor system> Figure 1 is a block diagram showing the configuration of a load sensor system according to an embodiment of the present invention.

[0020] The load sensor system shown in Figure 1 includes an electronic control unit 10 mounted in the vehicle as the main unit of the in-vehicle device. A recording card 21, a vehicle information input unit 22, a vehicle power supply 23, a wireless communication unit 24, four load sensor units 25A to 25D, a position information acquisition unit 26, and a setting PC 27 are connected to this electronic control unit 10.

[0021] Furthermore, the electronic control unit 10 includes a control unit 11, a main memory 12, an alarm output unit 13, a display unit 14, input / output interfaces 15 and 16, and a power supply unit 17.

[0022] The record card 21 is a non-volatile memory card that can be attached to and removed from the electronic control unit 10, and is provided individually for each driver. This record card 21 can be used to record operational record information, including information related to the quality of cargo transport.

[0023] The vehicle information input unit 22 can acquire information representing the status of the vehicle, such as an ignition on / off signal and a vehicle speed signal, and input it to the electronic control unit 10. The vehicle power supply 23 is a power source such as a battery installed in the vehicle, and can supply a predetermined DC power to on-board equipment such as the electronic control unit 10.

[0024] The wireless communication unit 24 can be used to wirelessly connect, for example, an external management device such as a data center with the electronic control unit 10.

[0025] Load sensor units 25A, 25B, 25C, and 25D are installed to measure the magnitude of the load applied to the suspension supporting the wheels at the front left (FL), front right (FR), rear left (RL), and rear right (RR) positions, respectively.

[0026] The location information acquisition unit 26 can acquire information representing the latitude / longitude of the vehicle's current position, for example, by using a GPS (Global Positioning System) receiver.

[0027] The configuration PC 27 can be connected to the electronic control unit 10 as needed to manage its functions and perform maintenance. For example, the configuration PC 27 can be used to register necessary data in tables on the electronic control unit 10 or to adjust various threshold values ​​and other parameters used to control the electronic control unit 10.

[0028] The control unit 11 is composed of an electronic circuit mainly consisting of a microcomputer, and by executing a pre-prepared program, it realizes various control functions required for the electronic control unit 10. This program includes a function to calculate the vehicle's load weight and total weight based on the loads detected by the four load sensor units 25A to 25D.

[0029] The main memory 12 includes a non-volatile memory (such as an EEPROM) on which various predetermined constant data and programs necessary for the operation of the electronic control unit 10 are written, and a memory (RAM) for holding temporary data.

[0030] The alarm output unit 13 is used to notify the driver of an abnormality using an alarm lamp or buzzer built into the electronic control device 10.

[0031] The display unit 14 is equipped with a flat-panel display positioned to be easily visible from the driver's position in the vehicle. Color images, text information, and other information can be displayed on the two-dimensional screen of this flat-panel display as needed. In this embodiment, the display unit 14 can be used to display the length of the waiting time until the vehicle is ready to begin measuring weight, or to indicate that measurement is now possible.

[0032] The input / output interface 15 performs signal processing for the control unit 11 to access data on the recording card 21 and controls signal input from the vehicle information input unit 22. The input / output interface 16 performs control for signal input and output between the wireless communication unit 24, the position information acquisition unit 26, each load sensor unit 25A to 25D, and the setting PC 27 and the control unit 11.

[0033] The power supply unit 17 generates stable DC power based on the power supplied from the vehicle power supply 23. The DC power output by the power supply unit 17 is supplied as power to each circuit inside the electronic control unit 10 and to each load sensor unit 25A to 25D.

[0034] <Configuration of the load sensor unit> Figure 2 is a block diagram showing an example configuration of one load sensor unit 25. Each of the load sensor units 25A to 25D shown in Figure 1 corresponds to the load sensor unit 25 in Figure 2.

[0035] As shown in Figure 2, this load sensor unit 25 incorporates a strain detection element 31, a dedicated IC (ASIC) 32, a temperature sensor 33, an MCU (microcontroller or microcomputer) 34, an input / output interface 35, and a power supply circuit 36.

[0036] The strain detection element 31 detects the amount of strain caused by the load applied to the location where it is installed. The dedicated IC 32 generates an electrical signal of voltage (V) corresponding to the amount of strain detected by the strain detection element 31, i.e., the load.

[0037] The temperature sensor 33 detects the temperature inside the load sensor unit 25 near the strain detection element 31 and outputs an electrical signal corresponding to that internal temperature.

[0038] Each component within the load sensor unit 25 is housed in a relatively small space within a designated case for protection and is isolated from the outside air. Therefore, when power is supplied to the internal circuitry of the load sensor unit 25, the temperature inside the case changes due to the heat generated by the dedicated IC 32, MCU 34, power supply circuit 36, etc. This internal temperature affects the physical characteristics of the strain detection element 31. The temperature sensor 33 detects this internal temperature.

[0039] The MCU34 generates data representing the magnitude of the load detected by the strain detection element 31 and data representing the internal temperature detected by the temperature sensor 33. The load and internal temperature detection data generated by the MCU34 are input to the electronic control unit 10 via the input / output interface 35.

[0040] <Example configuration of the truck vehicle being measured> Figures 3 to 5 show examples of the configuration of a truck vehicle 41 equipped with a load sensor system. Figure 3 is a front view of the truck vehicle 41, Figure 4 is a right side view of the truck vehicle 41, and Figure 5 is a bottom view of the truck vehicle 41.

[0041] In the example shown in Figure 3, the electronic control unit 10 is installed near the driver's seat of the truck vehicle 41. Four load sensor units 25A, 25B, 25C, and 25D connected to the electronic control unit 10 are installed near the left front wheel 44A, the right front wheel 44B, the left rear wheel 44C, and the right rear wheel 44D, respectively.

[0042] Various cargoes are loaded into the cargo bed 42 of the truck vehicle 41. Depending on the cargo load, the load at each position changes. In addition, the inclination angle of axle 43A, axle 43B, and the inclination angle of the axles in the longitudinal direction change according to the balance of the load at each position.

[0043] By installing multiple load sensor units 25A, 25B, 25C, and 25D in appropriate positions, it is possible to calculate the load weight and total weight of the truck vehicle 41 with relatively high accuracy, even when there is inclination on each axle 43A and 43B, based on the load detected by each load sensor unit 25A to 25D.

[0044] <Changes in internal sensor temperature> Figure 6 is a graph showing the relationship between the internal temperature of the load sensor unit 25 and the elapsed time since power-on. In Figure 6, the horizontal axis represents the length of time elapsed since power-on [minutes], and the vertical axis represents the internal temperature [°C].

[0045] In Figure 6, temperature characteristic curve C1 represents the change in internal temperature when the power is turned on with an internal temperature of 0°C. Temperature characteristic curve C2 represents the change in internal temperature when the power is turned on with an internal temperature of 24°C.

[0046] On the other hand, in the load sensor system shown in Figure 1, the characteristics of the strain detection element 31 in each load sensor unit 25A to 25D change with temperature. Therefore, if load measurement is performed when the internal temperature is fluctuating, a large measurement error may occur.

[0047] In particular, in the case of the load sensor system shown in Figure 1, for a while after power is turned on (the time is not constant), the internal temperature rises due to heat generated by the electronic circuit inside the load sensor unit 25, as shown by the temperature characteristic curves C1 and C2 in Figure 6. Therefore, if measurements are taken while the internal temperature is fluctuating, highly accurate measurement results cannot be obtained.

[0048] Therefore, to avoid increased measurement errors caused by fluctuations in internal temperature, it is common practice to operate the device in a way that prevents measurements from being taken until a certain waiting period has elapsed after the device is powered on. In other words, it is assumed that the internal temperature will saturate and stabilize after a predetermined waiting period has elapsed since the device was powered on, thus suppressing the occurrence of measurement errors caused by fluctuations in internal temperature.

[0049] However, as can be seen from the difference between temperature characteristic curves C1 and C2, for example, the actual fluctuation of the internal temperature is not constant, so if the waiting time is set to a fixed amount, there will be an excess or deficiency in the waiting time. In other words, if the waiting time is too short, measurement will start while the internal temperature is still fluctuating, which can lead to a relatively large measurement error. Also, if the waiting time is too long, workers will have to continue waiting even if the internal temperature has already reached a stable state, resulting in wasted time.

[0050] Therefore, the load sensor system shown in Figure 1 has a function to estimate the appropriate length of time required for the internal temperature to reach a stable state, depending on the situation, and to notify the user of that time.

[0051] <Temperature-Saturation Time Table> Figure 7 is a schematic diagram showing an example of the configuration of the temperature-saturation time table 61. Figure 8 is a graph showing an example of the characteristics of the temperature-saturation time table 61.

[0052] The internal temperature of the load sensor unit 25 slowly rises from power-on along an exponential curve as time progresses, as shown by the two temperature characteristic curves C1 and C2 in Figure 6. Furthermore, the slope of this curve gradually decreases over time, eventually reaching a saturation point where temperature fluctuations almost cease. This curve also changes significantly, as shown by temperature characteristic curves C1 and C2, mainly depending on the internal temperature at power-on.

[0053] The predicted saturation time shown in Figure 8 represents the predicted length of time from power-on until the internal temperature reaches the saturation point, and it changes depending on the internal temperature of the load sensor unit 25 at power-on. In other words, there is a correlation between the internal temperature of the load sensor unit 25 at power-on and the predicted saturation time, as shown in Figure 8.

[0054] Therefore, in this embodiment, a temperature-saturation time table 61, as shown in Figure 7, is created in advance based on data obtained, for example, by experimental measurement. By using this temperature-saturation time table 61, the predicted saturation time can be easily determined from the internal temperature at the time of power-on.

[0055] In the temperature-saturation time table 61 shown in Figure 7, the data for data item 61a representing the temperature inside the sensor and the data for data item 61b representing the predicted saturation time are registered side by side, linked to each other.

[0056] For example, if the internal temperature at power-on is 0°C, a predicted saturation time of 30 minutes can be determined from the contents of data item 61b in the temperature-saturation time table 61 shown in Figure 7. If the internal temperature at power-on is 40°C, a predicted saturation time of 8 minutes can be determined from the contents of data item 61b in the temperature-saturation time table 61.

[0057] In addition, in the temperature-saturation time table 61 in Figure 7, instead of the data item 61a representing the temperature inside the sensor, data of the gradient of the actual temperature fluctuation (initial temperature change per minute) from power-on to 1 minute may be registered.

[0058] <Operation of the load sensor system> <Processing of preparatory steps> Figure 9 shows the preparatory steps taken before using the load sensor system shown in Figure 1.

[0059] In the load sensor system, it is assumed that the data necessary for the operation of the electronic control unit 10 is entered and registered using the configuration PC 27 before the electronic control unit 10 is first used. Therefore, if the necessary data is already registered in the electronic control unit 10, the process shown in Figure 9 is unnecessary.

[0060] The administrator of the load sensor system shown in Figure 1 prepares correlation data, such as that shown in Figure 8, on the configuration PC 27, for example, as a result of experiments conducted in advance. Then, this data is transferred from the configuration PC 27 to the electronic control unit 10 and written and registered as a temperature-saturation time table 61, as shown in Figure 7, in the non-volatile memory (e.g., main memory 12) on the electronic control unit 10 (S01).

[0061] Furthermore, the administrator operates the configuration PC 27 to determine the temperature gradient threshold used to determine whether or not the internal temperature has saturated, and writes and registers this threshold in the non-volatile memory (e.g., main memory 12) on the electronic control unit 10 (S02).

[0062] <Characteristic behavior> The characteristic operation of the load sensor system shown in Figure 1 is illustrated in Figures 10 and 11. The operation shown in Figures 10 and 11 is described below.

[0063] The control unit 11 identifies in S11 whether or not power supply to the load sensor units 25A to 25D has started, and if power supply has started, it proceeds from S11 to S12. In S12, the control unit 11 acquires the latest data on strain (load at the relevant part) and internal temperature (t) output by each of the load sensor units 25A to 25D.

[0064] Based on the internal temperature data detected by the load sensor unit 25B, which detects load on the axle at the right front wheel (FR) position, the control unit 11 refers to the temperature-saturation time table 61 to obtain data for the predicted saturation time TFR at the FR position (S13).

[0065] Based on the internal temperature data detected by the load sensor unit 25A, which detects load on the axle at the left front wheel position (FL), the control unit 11 refers to the temperature-saturation time table 61 to obtain data for the predicted saturation time TFL at the FL position (S14).

[0066] Based on the internal temperature data detected by the load sensor unit 25D, which detects load on the axle at the right rear wheel (RR) position, the control unit 11 refers to the temperature-saturation time table 61 to obtain data for the predicted saturation time TRR at the RR position (S15).

[0067] Based on the internal temperature data detected by the load sensor unit 25C, which detects load on the axle at the left rear wheel (RL) position, the control unit 11 refers to the temperature-saturation time table 61 to obtain data for the predicted saturation time TFR at the RL position (S16).

[0068] The control unit 11 identifies the maximum value among the predicted saturation times TFR, TFL, TRR, and TRL for each position as the predicted saturation time TP0 (S17). The control unit 11 uses the audio output function of the alarm output unit 13 and the display function of the display unit 14 to notify the user of the electronic control device 10 of the predicted saturation time TP0 identified in S17 (S18).

[0069] The control unit 11 sets the length of the predicted saturation time TP0 in a predetermined internal timer and starts counting down the internal timer (S21). In other words, the internal timer makes it possible to determine whether or not the predicted saturation time TP0 has elapsed.

[0070] The control unit 11 clears the value of the internal counter C in S22. The control unit 11 stores the internal temperature (t) data acquired from each load sensor unit 25A to 25D in S12 into the internal memory t0 in S23.

[0071] The control unit 11 identifies in S24 whether the countdown of the internal timer has finished. If it has not finished, it proceeds to S25; if it has finished, it proceeds to the process in S30. In S25, the control unit 11 acquires the latest data on strain (load at the relevant part) and internal temperature (t) output by each of the load sensor units 25A to 25D.

[0072] The control unit 11 calculates the temperature gradient Δt for the internal temperature (t) of each load sensor unit 25A to 25D in S26. Since this temperature gradient Δt can be calculated as the temperature change per unit time, it is obtained as the difference between the latest internal temperature (t) acquired in S25 and the value in the internal memory t0 that holds the previous internal temperature value.

[0073] The control unit 11 compares the temperature gradient Δt calculated in S26 with its threshold (e.g., 0.1°C) in S27. If the temperature gradients Δt at each of the FR, FL, RR, and RL positions converge to within the threshold, the process proceeds from S27 to S28. If they do not converge to within the threshold, the process returns to S22 and repeats the above steps.

[0074] When the countdown of the internal timer ends, the control unit 11 notifies the user that the electronic control device 10 is ready to measure using the audio output function of the alarm output unit 13 and the display function of the display unit 14 (S30).

[0075] The control unit 11 updates the value of the internal counter C by adding "1" (S28). In other words, the number of times the condition in S27 is met is managed by the value of the internal counter C.

[0076] The control unit 11 compares the value of the internal counter C with its threshold (for example, "3") (S29). If the value of the internal counter C is equal to or greater than the threshold, the process proceeds from S29 to S31; otherwise, it returns to S23 and repeats the above process.

[0077] In other words, once the temperature gradients Δt at each of the FR, FL, RR, and RL positions have all converged sufficiently and the internal temperature can be considered to have stabilized in a saturated state, the control unit 11 proceeds to processing S29 through S31. Therefore, once the internal temperature actually stabilizes in a saturated state, processing S31 can proceed even before the predicted saturation time TP0 identified in S18 has elapsed.

[0078] The control unit 11 records actual data regarding the internal temperature in S31. That is, if the internal temperature stabilizes in a saturated state before the predicted saturation time TP0 has elapsed, the actual data is saved in the actual data recording unit 62, which will be described later. This actual data includes the internal temperature of each sensor immediately after power-on, acquired in S12, and the elapsed time until the conditions of S29 are met. This elapsed time can be obtained as the difference between the predicted saturation time TP0 and the value of the internal timer.

[0079] If the internal temperature stabilizes in a saturated state before the predicted saturation time TP0 has elapsed, the control unit 11 notifies the user that the electronic control device 10 has become ready for measurement using the audio output function of the alarm output unit 13 and the display function of the display unit 14 (S32).

[0080] After the electronic control unit 10 is ready for measurement, it can calculate temperature-corrected loads for each of the FR, FL, RR, and RL positions based on the strain data and internal temperature data detected by the four load sensor units 25A to 25D. Furthermore, by adding these loads together, the total weight or load weight of the entire truck vehicle 41 can be calculated.

[0081] Figure 12 is a flowchart showing an example of the table update process in a load sensor system. The process in Figure 12 is described below.

[0082] If the internal temperature actually saturated within a time shorter than the predicted saturation time TP0 determined based on the contents of the temperature-saturation time table 61, that actual data is recorded in the actual data recording unit 62 at S31 in Figure 11. Therefore, by performing the process shown in Figure 12 using the actual data on the actual data recording unit 62, it is possible to update the contents of the temperature-saturation time table 61 with more appropriate data.

[0083] For example, when it is time for a periodic update process to be required for the table, or when an update instruction is issued from the configuration PC 27 by the user, the control unit 11 of the electronic control unit 10 proceeds to the process from S41 to S42. The control unit 11 then acquires the performance data registered in the performance data recording unit 62 and performs an analysis of the performance data using predetermined statistical processing.

[0084] For example, in S42, the control unit 11 calculates the average elapsed time when the conditions in S29 are met for each internal temperature immediately after power-on in the actual data.

[0085] The control unit 11 analyzes the actual data in S42 and compares the data obtained with the contents of the temperature-saturation time table 61 in S43 to determine the time difference for each internal temperature, and generates optimized updated data that takes this difference into account. The control unit 11 registers the updated data generated in S43 into the temperature-saturation time table 61 in S44, and updates the contents of the temperature-saturation time table 61.

[0086] Furthermore, the present invention is not limited to the embodiments described above, and can be modified, improved, etc., as appropriate. In addition, the material, shape, dimensions, number, placement, etc. of each component in the embodiments described above are arbitrary and not limited, as long as they can achieve the present invention.

[0087] For example, the load sensor system shown in Figure 1 assumes the simultaneous use of four load sensor units 25A to 25D, but the present invention can also be applied when only one load sensor unit 25 is used. Furthermore, it is conceivable that the number of load sensor units 25 used may be increased depending on the number of axles of the vehicle.

[0088] Furthermore, while the load sensor system shown in Figure 1 assumes that each of the four load sensor units 25A to 25D has a built-in temperature sensor 33, it is possible to predict the internal temperature saturation time if one or more of the four load sensor units 25A to 25D have a temperature sensor 33.

[0089] Furthermore, while the load sensor system described above calculates the predicted saturation time using the temperature-saturation time table 61, it is also possible to estimate the saturation time by calculation using predetermined constants and a set calculation formula, based on the internal temperature at power-on or the gradient of the internal temperature change immediately after power-on.

[0090] Herein, the features of the load sensor system according to the embodiment of the present invention described above are briefly summarized and listed below in [1] to [5]. [1] Onboard unit (electronic control unit 10) and A sensor unit (load sensor unit 25) is attached to the axle (43A, 43B) and connected to the on-board device, Equipped with, The sensor unit has the function of outputting a signal of the internal temperature detected inside the unit and a signal of the strain detected on the axle. The in-vehicle device has the function of estimating the time it takes for the internal temperature to saturate based on the signal output from the sensor unit (S12-S17), and notifying the estimated time (S18). Load sensor system.

[0091] According to the load sensor system with the configuration described in [1] above, the time required for the internal temperature of the sensor unit to saturate is estimated and notified, so that load measurement can be started when there is no fluctuation in the internal temperature. Therefore, measurement errors due to temperature fluctuations caused by heat generation inside the device can be reduced. Moreover, the waiting time until the internal temperature saturates can be shortened, reducing wasted time.

[0092] [2] The in-vehicle device includes a temperature saturation table (temperature-saturation time table 61) that holds a constant for the time required for the internal temperature to reach the saturation temperature for each of a plurality of temperature values ​​corresponding to the internal temperature, Based on the measured internal temperature and the temperature saturation table, the time required for the internal temperature to reach the saturation temperature (predicted saturation time TP0) is estimated. The load sensor system described in [1] above.

[0093] According to the load sensor system with the configuration described in [2] above, the required time can be calculated with relatively high accuracy and instantaneously without requiring complex calculations.

[0094] [3] The in-vehicle unit has a temperature change monitoring unit (S25~S29) that monitors changes in the measured internal temperature, If the temperature change monitoring unit detects saturation of the measured internal temperature, the in-vehicle device permits notification of temperature saturation before the estimated time for the internal temperature is reached (S29, S32). The load sensor system described in [1] or [2] above.

[0095] According to the load sensor system with the configuration described in [3] above, if the internal temperature measurement is saturated before the estimated time has elapsed, the waiting time before starting load measurement can be reduced relative to the estimated time.

[0096] [4] The in-vehicle unit has a temperature change monitoring unit (S25~S29) that monitors changes in the measured internal temperature, The in-vehicle device updates the registered contents of the temperature saturation table based on the actual time at which the temperature change monitoring unit detected the saturation of the measured internal temperature (see Figure 12). The load sensor system described in [2] or [3] above.

[0097] According to the load sensor system configured as described in [4] above, it becomes easier to optimize the contents of the temperature saturation table by reflecting actual data of internal temperature and time detected under actual operating conditions.

[0098] [5] Multiple sensor units (load sensor units 25A to 25D) arranged at different positions are connected to the in-vehicle device, The in-vehicle device prioritizes notifying the latest time among the time it takes for the internal temperature of each of the multiple sensor units to saturate (S17, S18). A load sensor system as described in any of the above [1] to [4].

[0099] According to the load sensor system with the configuration described in [5] above, even if the internal temperature fluctuation characteristics of the multiple sensor units used simultaneously differ significantly, load measurement can be started only after the internal temperature fluctuations of all sensor units have stabilized. Therefore, the reliability of the measurement results is improved. [Explanation of Symbols]

[0100] 10 Electronic control unit 11 Control Unit 12 Internal memory 13 Alarm output section 14 Display section 15,16 Input / Output Interfaces 17 Power supply section 21 Record Card 22 Vehicle Information Input Section 23 Vehicle power supply 24 Wireless Communication Section 25, 25A, 25B, 25C, 25D Load Sensor Unit 26 Location information acquisition section 27 PC for configuration 31. Strain detection element 32 Dedicated IC 33 Temperature Sensor 34 MCU 35 Input / Output Interfaces 36 Power supply circuit 41 Truck Vehicles 42 cargo bed 43A,43B Axle 44A,44B,44C,44D wheels 61 Temperature-Saturation Time Table 61a, 61b Data items 62 Performance Data Recording Section C1, C2 temperature characteristic curves TFR,TFL,TRR,TRL time TP0 Predicted Saturation Time

Claims

1. In-vehicle device, A sensor unit mounted on the axle and connected to the on-board device, Equipped with, The sensor unit has the function of outputting a signal of the internal temperature detected inside the unit and a signal of the strain detected on the axle. The in-vehicle device has a function to estimate the time it takes for the internal temperature to saturate based on the signal output from the sensor unit, and to notify the estimated time, It has a temperature change monitoring unit that monitors changes in the measured internal temperature, The in-vehicle device, when the temperature change monitoring unit detects saturation of the measured internal temperature, permits notification of temperature saturation before the estimated time for the internal temperature is reached. Load sensor system.

2. The in-vehicle device includes a temperature saturation table that holds a constant for the time required for the internal temperature to reach a saturation temperature for each of a plurality of temperature values ​​corresponding to the internal temperature. Based on the measured internal temperature and the temperature saturation table, the time required for the internal temperature to reach the saturation temperature is estimated. The load sensor system according to claim 1.

3. An in-vehicle device, A sensor unit mounted on the axle and connected to the on-board device, Equipped with, The sensor unit has the function of outputting a signal of the internal temperature detected inside the unit and a signal of the strain detected on the axle. The in-vehicle device has a function to estimate the time it takes for the internal temperature to saturate based on the signal output from the sensor unit, and to notify the estimated time. For each of the multiple temperature values ​​corresponding to the aforementioned internal temperature, a temperature saturation table is provided that holds a constant for the time required until the internal temperature reaches the saturation temperature. Based on the measured internal temperature and the temperature saturation table, the time required for the internal temperature to reach the saturation temperature is estimated, The in-vehicle device has a temperature change monitoring unit that monitors changes in the measured internal temperature, The in-vehicle device updates the registered contents of the temperature saturation table, reflecting the actual time at which the temperature change monitoring unit detected the saturation of the measured internal temperature. Load sensor system.

4. An in-vehicle device, A sensor unit mounted on the axle and connected to the on-board device, Equipped with, The sensor unit has the function of outputting a signal of the internal temperature detected inside the unit and a signal of the strain detected on the axle. The in-vehicle device has a function to estimate the time it takes for the internal temperature to saturate based on the signal output from the sensor unit, and to notify the estimated time. Multiple sensor units, each positioned at a different location, are connected to the in-vehicle device. The in-vehicle device prioritizes notifying the latest time among the times when the internal temperature of each of the multiple sensor units becomes saturated. Load sensor system.

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