JP2023154339A - load sensor system - Google Patents

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

The present invention relates to a load sensor system that can be used to measure loaded weight in a vehicle.

For example, in a vehicle such as a tank truck, it is necessary to measure the weight of the loaded object. Furthermore, in large vehicles such as trucks, it is necessary to measure the weight of the loaded items or the total weight of the vehicle to prevent overloading. Conventional techniques of measuring devices that can be used for such purposes are disclosed in, for example, Patent Document 1 and Patent Document 2.

Patent Document 1 discloses a technique for easily correcting load sensor output changes due to temperature changes and measuring loaded weight and 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, if the change is large, the latest sensor detection output is taken in without correction.

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

Japanese Patent Application Publication No. 10-9937 Japanese Patent Application Publication No. 11-160140

Devices that detect loads such as on vehicle axles use sensors such as strain gauges to detect loads, so physical characteristics change due to temperature changes, causing fluctuations in the output signal. do. Therefore, measures such as those described in Patent Document 1 and Patent Document 2 are required to prevent temperature changes from affecting measured values.

In addition, when using a sensor unit that integrates a heat-generating electronic circuit and a sensor such as a strain gauge, it is important to note that not only changes in the environmental temperature such as the outside air, but also changes in the internal temperature due to the heat generation of the sensor itself must be taken into account.

Therefore, when actually measuring a load, it is recommended that the user be notified that measurement is possible after a certain waiting time (for example, 30 minutes) has passed after the measuring device is turned on. Generally, it is operated in In other words, once a certain waiting time has elapsed after the measurement device was powered on, fluctuations in the internal temperature caused by the sensor's own heat generation are thought to almost disappear, so measurement errors caused by temperature fluctuations can be reduced. Can be done.

However, the time required from when the measuring device is turned on until the internal temperature actually stops changing is not constant. For example, the required time tends to be longer under conditions where the environmental temperature around the sensor is relatively low. Therefore, even if the load is measured after the waiting time has elapsed, errors due to internal temperature fluctuations may increase under conditions where the environmental temperature is low. Furthermore, if the waiting time is set to be long in order to reduce errors caused by internal temperature fluctuations, load measurement cannot be started until the waiting time has elapsed even after the internal temperature fluctuations have actually stopped. It is inevitable that more time will be wasted.

On the other hand, when adopting the technology of Patent Document 1, a sensor output change below a predetermined value is determined to be simply caused by a temperature change, so if this determination is incorrect, the load measurement accuracy will be affected. expected to decline.

Furthermore, when adopting the technology of Patent Document 2, temperature correction is performed after a predetermined period of time has elapsed from the start/stop of the engine, so the occurrence of unnecessary waiting time is unavoidable, and if the waiting time is insufficient, Errors occur due to internal temperature fluctuations. Furthermore, a G sensor and a vehicle height sensor are required to detect the behavior of the vehicle. Furthermore, the outputs of these sensors fluctuate due to the influence of wind, etc., which causes measurement errors.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to suppress the occurrence of load measurement errors caused by internal temperature fluctuations of the sensor, and to reduce the waiting time until a state in which measurement can be started. The object of the present invention is to provide a load sensor system that can be shortened.

The above object according to the present invention is achieved by the following configuration.

On-board equipment and
a sensor unit attached to an axle and connected to the on-vehicle device;
Equipped with
The sensor unit has a function of outputting an internal temperature signal detected inside the unit and a strain signal detected on the axle,
The vehicle-mounted device has a function of estimating the time when the internal temperature is saturated based on the signal output from the sensor unit, and notifying the estimated time.
Load sensor system.

According to the load sensor system of the present invention, actual load measurement can be started after the internal temperature is saturated and almost no temperature fluctuation occurs. Therefore, the occurrence of errors due to the temperature characteristics of the sensor is suppressed, and measurement accuracy is improved. Furthermore, the waiting time from turning on the device to starting load measurement can be shortened.

The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the mode for carrying out the invention (hereinafter referred to as "embodiment") described below with reference to the accompanying drawings. .

FIG. 1 is a block diagram showing the configuration of a load sensor system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration example of one load sensor unit. FIG. 3 is a front view showing a configuration example of a truck vehicle equipped with a load sensor system. FIG. 4 is a right side view showing a configuration example of a truck vehicle equipped with a load sensor system. FIG. 5 is a bottom view showing a configuration example of a truck vehicle equipped with a load sensor system. FIG. 6 is a graph showing the relationship between the internal temperature of the load sensor unit and the elapsed time since the power was turned on. FIG. 7 is a schematic diagram showing a configuration example of a temperature-saturation time table. FIG. 8 is a graph showing an example of the characteristics of the temperature-saturation time table. FIG. 9 is a flowchart showing the preparation process before using the load sensor system. FIG. 10 is a flowchart showing a portion of characteristic operations in the load sensor system. FIG. 11 is a flowchart showing a portion of characteristic operations in the load sensor system. FIG. 12 is a flowchart illustrating an example of table update processing in the load sensor system.

Specific embodiments of the present invention will be described below with reference to each figure.

<Load sensor system configuration>
FIG. 1 is a block diagram showing the configuration of a load sensor system according to an embodiment of the present invention.

The load sensor system shown in FIG. 1 includes an electronic control device 10 that is mounted on a vehicle as a main body of an on-vehicle device. Further, a recording card 21, a vehicle information input section 22, a vehicle power supply 23, a wireless communication section 24, four load sensor units 25A to 25D, a position information acquisition section 26, and a setting personal computer 27 are connected to this electronic control device 10. ing.

The electronic control device 10 also includes a control section 11 , a main body memory 12 , an alarm output section 13 , a display section 14 , input/output I/Fs (interfaces) 15 and 16 , and a power supply section 17 .

The recording card 21 is a nonvolatile memory card that is removably attached to the electronic control device 10, and is prepared individually for each driver. This record card 21 can be used to record operation record information including information related to the transportation quality of cargo.

The vehicle information input unit 22 can acquire information representing the state of the vehicle, such as a signal indicating whether the ignition is turned on or off, or a vehicle speed signal, and input the acquired information to the electronic control device 10 .
The vehicle power source 23 is a power source such as a battery mounted on the vehicle, and can supply predetermined DC power to on-vehicle devices such as the electronic control device 10.

The wireless communication unit 24 can be used to connect a management device outside the vehicle, such as a data center, and the electronic control device 10 by wireless communication.

Load sensor units 25A, 25B, 25C, and 25D are added to suspensions that support wheels at front left (FL), front right (FR), rear left (RL), and rear right (RR) positions, respectively. It is installed so that the magnitude of the load can be measured.

The position information acquisition unit 26 can acquire information representing the latitude/longitude of the current position of the own vehicle using, for example, a GPS (Global Positioning System) receiver.

The setting personal computer 27 can be connected to the electronic control device 10 as needed when managing the functions of the electronic control device 10 or performing maintenance. For example, the setting personal computer 27 can be used to register necessary data in a table on the electronic control device 10 or to adjust parameters such as various threshold values used to control the electronic control device 10.

The control unit 11 is constituted by an electronic circuit mainly including a microcomputer, and implements various control functions required by the electronic control device 10 by executing programs prepared in advance. This program includes a function to calculate the loaded weight and total weight of the own vehicle based on the loads detected by the four load sensor units 25A to 25D.

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

The alarm output unit 13 is used to notify the driver of the occurrence of an abnormality using an alarm lamp, a buzzer, etc. built into the electronic control device 10.

The display unit 14 includes a flat display that is arranged to be easily visible from the driver's position of the host vehicle. Color images and text information can be displayed as needed on the two-dimensional screen of this flat display. In this embodiment, the display unit 14 can be used to display the length of waiting time until weight measurement can be started, and to display that measurement is now possible.

The input/output I/F 15 performs signal processing for the control unit 11 to access data on the recording card 21 and control for signal input from the vehicle information input unit 22. The input/output I/F 16 controls signal input/output between the wireless communication section 24, the position information acquisition section 26, each of the load sensor units 25A to 25D, and the setting personal computer 27 and the control section 11.

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

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

As shown in FIG. 2, this load sensor unit 25 includes a strain detection element 31, a dedicated IC (ASIC) 32, a temperature sensor 33, an MCU (microcontroller or microcomputer) 34, an input/output I/F 35, and a power supply circuit. It has 36 built-in.

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 electric signal of voltage (V) corresponding to the amount of strain detected by the strain detection element 31, that is, the load.

The temperature sensor 33 detects the temperature inside the load sensor unit 25 near the strain detection element 31, and outputs an electric signal according to the internal temperature.

Each component within the load sensor unit 25 is housed in a relatively small space within a predetermined case for protection and isolated from the outside air. Therefore, when power supply starts to be supplied to the internal circuit of the load sensor unit 25, the temperature inside the case changes under the influence of heat generated by the dedicated IC 32, MCU 34, power supply circuit 36, and the like. This internal temperature affects the physical characteristics of the strain sensing element 31. A temperature sensor 33 detects this internal temperature.

The MCU 34 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, respectively. The load and internal temperature detection data generated by the MCU 34 are input to the electronic control unit 10 via the input/output I/F 35.

<Example of configuration of truck vehicle to be measured>
Examples of the configuration of a truck vehicle 41 equipped with a load sensor system are shown in FIGS. 3 to 5. 3 is a front view of the truck vehicle 41, FIG. 4 is a right side view of the truck vehicle 41, and FIG. 5 is a bottom view of the truck vehicle 41.

In the example shown in FIG. 3, the electronic control device 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 device 10 respectively control the left front wheel 44A, the right front wheel 44B, the left rear wheel 44C, and the right rear wheel 44D. It is located nearby.

Various cargoes are loaded into the interior space of the loading platform 42 of the truck vehicle 41. The load at each position varies depending on the loading status of the cargo. Furthermore, the inclination angle of the axle 43A, the inclination angle of the axle 43B, and the inclination angle of the axle in the longitudinal direction vary depending on the balance of loads at each position.

By installing a plurality of load sensor units 25A, 25B, 25C, and 25D at appropriate positions, even when each axle 43A, 43B is tilted, the load detected by each load sensor unit 25A to 25D can be adjusted. Based on this, it is possible to calculate the loaded weight and total weight of the truck vehicle 41 with relatively high accuracy.

<Change in sensor internal temperature>
FIG. 6 is a graph showing the relationship between the internal temperature of the load sensor unit 25 and the elapsed time since the power was turned on. In FIG. 6, the horizontal axis represents the length of time [minutes] that has passed since the power was turned on, and the vertical axis represents the internal temperature [° C.].

In FIG. 6, a temperature characteristic curve C1 represents a change in the internal temperature when the power is turned on when the internal temperature is 0 [° C.]. Further, a temperature characteristic curve C2 represents a change in the internal temperature when the power is turned on when the internal temperature is 24 [° C.].

On the other hand, in the load sensor system shown in FIG. 1, the characteristics of the strain detection elements 31 in each load sensor unit 25A to 25D change depending on the temperature. Therefore, if the load is measured while the internal temperature is fluctuating, a large measurement error may occur.

In particular, in the case of the load sensor system shown in FIG. 1, for a while (the time is not constant) after the power is turned on, the temperature shown in FIG. Since the internal temperature increases as shown in the characteristic curves C1 and C2, highly accurate measurement results cannot be obtained if measurement is performed while the internal temperature is fluctuating.

Therefore, in order to avoid increasing measurement errors due to internal temperature fluctuations, it is common practice to operate the device so that no measurements are taken until a certain waiting time has elapsed after the device is powered on. It is being said. In other words, the internal temperature is considered to be saturated and stabilized after a predetermined waiting time has elapsed after the device is powered on, so it is possible to suppress the occurrence of measurement errors due to fluctuations in the internal temperature.

However, as can be seen from, for example, the difference between the temperature characteristic curves C1 and C2, actual fluctuations in the internal temperature are not constant, so if the waiting time is set to a constant time, excess or deficiency in the waiting time will occur. In other words, if the waiting time is too short, measurement will start when the internal temperature continues to fluctuate, which may result in a relatively large measurement error. Furthermore, if the waiting time is too long, the operator or the like has to continue waiting even if the internal temperature has already reached a stable state, resulting in wasted time.

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

<Temperature-saturation time table>
FIG. 7 is a schematic diagram showing a configuration example of the temperature-saturation time table 61. FIG. 8 is a graph showing an example of the characteristics of the temperature-saturation time table 61.

The internal temperature of the load sensor unit 25 slowly rises along an exponential curve as time passes from power-on, as shown by the two types of temperature characteristic curves C1 and C2 shown in FIG. Further, the slope of this curve gradually decreases over time, and eventually reaches a saturation point, where temperature fluctuations almost disappear. Further, this curve changes greatly depending on the internal temperature when the power is turned on, as shown in the temperature characteristic curves C1 and C2.

The predicted saturation time shown in FIG. 8 represents a predicted value of the length of time from when the power is turned on until the internal temperature reaches the saturation point, and changes depending on the internal temperature of the load sensor unit 25 when the power is turned on. . That is, there is a correlation as shown in FIG. 8, for example, between the internal temperature of the load sensor unit 25 when the power is turned on and the predicted saturation time.

Therefore, in this embodiment, a temperature-saturation time table 61 as shown in FIG. 7 is created in advance, based on data obtained through experimental measurements, for example. By using this temperature-saturation time table 61, the predicted saturation time can be easily determined from the internal temperature when the power is turned on.

In the temperature-saturation time table 61 shown in FIG. 7, data in a data item 61a representing the sensor internal temperature and data in a data item 61b representing the predicted saturation time are registered side by side in a state where they are linked to each other.

For example, if the internal temperature when the power is turned on is 0 [°C], the predicted saturation time of 30 [minutes] can be calculated from the contents of the data item 61b of the temperature-saturation time table 61 shown in FIG. can. Furthermore, if the internal temperature at power-on is 40 [° C.], a predicted saturation time of 8 [minutes] can be obtained from the contents of the data item 61b of the temperature-saturation time table 61.

In the temperature-saturation time table 61 of FIG. 7, instead of the data item 61a representing the sensor internal temperature, for example, the gradient of the actual temperature fluctuation (initial Data on temperature change per minute) may also be registered.

<Operation of load sensor system>
<Advance preparation processing>
FIG. 9 shows the preparation process before using the load sensor system shown in FIG. 1.

In the load sensor system, it is assumed that before using the electronic control device 10 for the first time, data necessary for the operation of the electronic control device 10 is input and registered using the setting personal computer 27. Therefore, if the necessary data is registered in advance in the electronic control device 10, the process in FIG. 9 is unnecessary.

The administrator of the load sensor system shown in FIG. 1 has prepared correlation data as shown in FIG. 8 on the setting personal computer 27, for example, as a result of conducting experiments in advance. Then, this data is transferred from the setting personal computer 27 to the electronic control unit 10, and is written and registered in the nonvolatile memory (for example, the main body memory 12) on the electronic control unit 10 as a temperature-saturation time table 61 as shown in FIG. (S01).

In addition, the administrator operates the setting personal computer 27 to determine a temperature gradient threshold value to be used in a determination to identify whether or not the internal temperature is saturated, and stores this threshold value in the nonvolatile memory on the electronic control unit 10. (For example, the main body memory 12) is written and registered (S02).

<Characteristic movements>
Characteristic operations in the load sensor system shown in FIG. 1 are shown in FIGS. 10 and 11. The operations in FIGS. 10 and 11 will be explained below.

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

The control unit 11 refers to the temperature-saturation time table 61 based on the internal temperature data detected by the load sensor unit 25B that detects the load on the axle at the front right (FR) position, and determines the predicted saturation time for the FR position. Acquire TFR data (S13).

The control unit 11 refers to the temperature-saturation time table 61 based on the internal temperature data detected by the load sensor unit 25A that detects the load on the axle at the front left side (FL) position, and determines the predicted saturation time at the FL position. TFL data is acquired (S14).

The control unit 11 refers to the temperature-saturation time table 61 based on the internal temperature data detected by the load sensor unit 25D that detects the load on the axle at the rear right (RR) position, and calculates the predicted saturation of the RR position. Time TRR data is acquired (S15).

The control unit 11 refers to the temperature-saturation time table 61 based on the internal temperature data detected by the load sensor unit 25C that detects the load on the axle at the left rear wheel (RL) position, and calculates the predicted saturation of the RL position. Time TFR data is acquired (S16).

The control unit 11 specifies the maximum value among the predicted saturation times TFR, TFL, TRR, and TRL at 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 specified in S17 (S18).

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). That is, it is possible to determine whether or not the predicted saturation time TP0 has elapsed using the internal timer.

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 of the load sensor units 25A to 25D in S12 in the internal memory t0 in S23.

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

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

The control unit 11 compares the temperature gradient Δt calculated in S26 with its threshold value (for example, 0.1° C.) in S27. If the temperature gradients Δt at each of the FR, FL, RR, and RL positions have all converged within the threshold value, the process proceeds from S27 to S28, and if the temperature gradients have not converged within the threshold value, the process returns to S22 and repeats the above process.

When the countdown of the internal timer has ended, 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 utilize the fact that the electronic control unit 10 is in a measurable state. (S30).

The control unit 11 adds "1" to the value of the internal counter C to update it (S28). That is, the number of times the condition of S27 is satisfied is managed by the value of the internal counter C.

The control unit 11 compares the value of the internal counter C with its threshold value (for example, "3") (S29). If the value of the internal counter C exceeds the threshold value, the process proceeds from S29 to S31; if this condition is not met, the process returns to S23 and repeats the above process.

That is, when all the temperature gradients Δt at the FR, FL, RR, and RL positions have sufficiently converged and the internal temperature can be considered stable in a saturated state, the control unit 11 proceeds to the processing from S29 to S31. Therefore, when the internal temperature is actually stabilized in a saturated state, the process can proceed to S31 even before the predicted saturation time TP0 specified in S18 has elapsed.

The control unit 11 records performance data regarding the internal temperature in S31. That is, if the internal temperature stabilizes in a saturated state before the predicted saturation time TP0 elapses, the performance data is stored in the performance data recording unit 62, which will be described later. This performance data includes data on the internal temperature of each sensor immediately after the power is turned on, obtained in S12, and the elapsed time until the condition in S29 is satisfied. This elapsed time can be obtained as the difference between the predicted saturation time TP0 and the value of the internal timer.

If the internal temperature stabilizes in the saturated state before the predicted saturation time TP0 elapses, 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 control the electronic control unit 10. The user is notified that the state is ready for measurement (S32).

After the electronic control unit 10 is in a measurable state, the four load sensor units 25A to 25D calculate the temperature-corrected load based on the strain amount data and internal temperature data respectively detected by the four load sensor units 25A to 25D. It can be calculated for each position of RR and RL. Furthermore, by adding these loads, the total weight or loaded weight of the entire truck vehicle 41 can be calculated.

<Table update process>
FIG. 12 is a flowchart illustrating an example of table update processing in the load sensor system. The processing in FIG. 12 will be explained below.

If the internal temperature actually becomes saturated within a time shorter than the predicted saturation time TP0 determined based on the contents of the temperature-saturation time table 61, the actual data is stored in the actual data recording unit 62 in S31 of FIG. recorded. Therefore, by executing the process shown in FIG. 12 using the performance data on the performance data recording section 62, it is possible to update the contents of the temperature-saturation time table 61 to more appropriate data.

For example, at a regular timing when table update processing is required, or when an update instruction is issued from the setting personal computer 27 due to a user operation, the control unit 11 of the electronic control unit 10 performs the processing from S41 to S42. move on. Then, the control unit 11 acquires the performance data registered in the performance data recording unit 62, and analyzes the performance data through predetermined statistical processing.

For example, in S42, the control unit 11 calculates the average value of the elapsed time when the condition of S29 is satisfied for each internal temperature immediately after power-on in the performance data.

The control unit 11 compares the data obtained by analyzing the performance data in S42 with the contents of the temperature-saturation time table 61 in S43 to find the difference in time for each internal temperature, and takes this difference into consideration. Generate optimized update data.
The control unit 11 registers the update data generated in S43 in the temperature-saturation time table 61 in S44, and updates the contents of the temperature-saturation time table 61.

Note that the present invention is not limited to the embodiments described above, and can be modified, improved, etc. as appropriate. In addition, the material, shape, size, number, arrangement location, etc. of each component in the above-described embodiments are arbitrary as long as the present invention can be achieved, and are not limited.

For example, in the load sensor system shown in FIG. 1, it is assumed that four load sensor units 25A to 25D are used at the same time, but the present invention is applicable even when only one load sensor unit 25 is used. can. It is also envisioned that the number of load sensor units 25 to be used will be further increased depending on the number of axles of the vehicle.

Furthermore, in the load sensor system shown in FIG. 1, it is assumed that each of the four load sensor units 25A to 25D has a built-in temperature sensor 33, but one of the four load sensor units 25A to 25D If the temperature sensor 33 is provided as described above, it is possible to predict the saturation time of the internal temperature.

In addition, in the above-mentioned load sensor system, the predicted saturation time is calculated using the temperature-saturation time table 61. The saturation time can also be estimated by calculation from the internal temperature or the gradient of internal temperature change immediately after power is turned on.

Here, the features of the load sensor system according to the embodiment of the present invention described above will be briefly summarized and listed below in [1] to [5].
[1] On-vehicle device (electronic control device 10),
a sensor unit (load sensor unit 25) attached to the axle (43A, 43B) and connected to the on-vehicle device;
Equipped with
The sensor unit has a function of outputting an internal temperature signal detected inside the unit and a strain signal detected on the axle,
The on-vehicle device has a function of estimating the time when the internal temperature is saturated based on the signal output from the sensor unit (S12 to S17), and notifying the estimated time (S18).
Load sensor system.

According to the load sensor system having the configuration [1] above, since the time when the internal temperature of the sensor unit is saturated is estimated and notified, load measurement can be started in a state where no fluctuation occurs in the internal temperature. Therefore, measurement errors due to temperature fluctuations caused by heat generation inside the device can be reduced. Furthermore, it is possible to shorten the waiting time until the internal temperature is saturated, thereby reducing wasted time.

[2] The on-vehicle device stores a temperature saturation table (temperature-saturation time table 61) that holds a constant of the time required for the internal temperature to reach the saturation temperature for each of the plurality of temperature values corresponding to the internal temperature. ),
estimating the time required for the internal temperature to reach the saturation temperature (predicted saturation time TP0) based on the temperature saturation table from the measured value of the internal temperature;
The load sensor system according to [1] above.

According to the load sensor system having the configuration [2] above, the required time can be calculated instantaneously with relatively high precision without requiring complicated calculation processing.

[3] The vehicle-mounted device has a temperature change monitoring unit (S25 to S29) that monitors changes in the measured value of the internal temperature,
When the temperature change monitoring unit detects saturation of the measured value of the internal temperature, the on-vehicle device allows notification of temperature saturation before reaching the estimated time of the internal temperature (S29, S32);
The load sensor system according to [1] or [2] above.

According to the load sensor system configured in [3] above, if the measured value of the internal temperature is saturated before the estimated time elapses, the waiting time to start measuring the load is shortened relative to the estimated time. can.

[4] The vehicle-mounted device has a temperature change monitoring unit (S25 to S29) that monitors changes in the measured value of the internal temperature,
The on-vehicle device updates the registered contents of the temperature saturation table by reflecting the actual time when the temperature change monitoring unit detects saturation of the measured value of the internal temperature (see FIG. 12);
The load sensor system according to [2] or [3] above.

According to the load sensor system having the configuration [4] above, it becomes easy to optimize the contents of the temperature saturation table by reflecting the internal temperature and time performance data detected under the actual usage environment.

[5] A plurality of the sensor units (load sensor units 25A to 25D) arranged at mutually different positions are connected to the on-vehicle device,
The on-vehicle device preferentially notifies the latest time among the times when the internal temperature of each of the plurality of sensor units is saturated (S17, S18);
The load sensor system according to any one of [1] to [4] above.

According to the load sensor system configured as described in [5] above, even if a plurality of sensor units used at the same time include sensor units with greatly different internal temperature fluctuation characteristics, the internal temperature of all sensor units is After the fluctuations are gone, you can start measuring the load. Therefore, the reliability of the measurement results is improved.

10 Electronic control unit 11 Control unit 12 Main unit memory 13 Alarm output unit 14 Display unit 15, 16 Input/output I/F
17 Power supply unit 21 Recording card 22 Vehicle information input unit 23 Vehicle power supply 24 Wireless communication unit 25, 25A, 25B, 25C, 25D Load sensor unit 26 Position information acquisition unit 27 Setting personal computer 31 Distortion detection element 32 Dedicated IC
33 Temperature sensor 34 MCU
35 Input/output I/F
36 Power supply circuit 41 Truck vehicle 42 Loading platform 43A, 43B Axle 44A, 44B, 44C, 44D Wheel 61 Temperature-saturation time table 61a, 61b Data item 62 Actual data recording section C1, C2 Temperature characteristic curve TFR, TFL, TRR, TRL time TP0 Predicted saturation time

Claims (5)

On-board equipment and
a sensor unit attached to an axle and connected to the on-vehicle device;
Equipped with
The sensor unit has a function of outputting an internal temperature signal detected inside the unit and a strain signal detected on the axle,
The vehicle-mounted device has a function of estimating the time when the internal temperature is saturated based on the signal output from the sensor unit, and notifying the estimated time.
Load sensor system. The vehicle-mounted device includes a temperature saturation table that holds a constant of the time required for the internal temperature to reach a saturation temperature for each of the plurality of temperature values corresponding to the internal temperature,
estimating the time required for the internal temperature to reach the saturation temperature based on the temperature saturation table from the measured value of the internal temperature;
The load sensor system according to claim 1. The vehicle-mounted device includes a temperature change monitoring unit that monitors changes in the measured value of the internal temperature,
When the temperature change monitoring unit detects saturation of the measured value of the internal temperature, the on-vehicle device allows notification of temperature saturation before reaching the estimated time of the internal temperature.
The load sensor system according to claim 1. The vehicle-mounted device includes a temperature change monitoring unit that monitors changes in the measured value of the internal temperature,
The on-vehicle device updates the registered contents of the temperature saturation table, reflecting the actual time when the temperature change monitoring unit detected saturation of the measured value of the internal temperature.
The load sensor system according to claim 2. A plurality of the sensor units arranged at mutually different positions are connected to the on-vehicle device,
The on-vehicle device preferentially notifies the latest time among the times when the internal temperatures of each of the plurality of sensor units are saturated.
The load sensor system according to claim 1.

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