JP4751235B2 - Vehicle loading weight calculation method and apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for calculating the load weight of a vehicle based on a load signal output from a strain detection type load sensor attached to the vehicle, and more particularly to correcting fluctuations in the output of the load sensor due to temperature. The present invention relates to a vehicle weight calculation method and apparatus.

When a load sensor of strain detection type such as a strain gauge is attached to a place such as an axle shaft that expands and contracts due to the load from the load, the load sensor accompanying the temperature change is used to calculate the load weight of the vehicle from the output. It is necessary to correct the fluctuations in the output of the load sensor, and as such, there has already been proposed one that corrects the output of the load sensor in proportion to the amount of temperature shift with respect to the reference temperature obtained using the temperature sensor (thermistor). (For example, Patent Document 1).
JP 2000-28423 A

  By the way, fluctuations in the output of the load sensor due to temperature changes are not only caused by changes in the output characteristics due to the temperature dependence of the load sensor itself, so-called temperature drift, but also due to temperature changes due to heat transmitted from the heat source to the load sensor installation target. Also brought about by stretching.

  Among these, load sensor output fluctuation caused by so-called temperature drift follows the change in ambient temperature of the load sensor in real time, but load sensor output fluctuation caused by expansion and contraction due to temperature change of the installation target is Because there is a gap between the heat transfer rate and the heat deformation rate, the temperature change of the mounting target does not follow in real time, and the output fluctuation of the load sensor due to the expansion and contraction of the mounting target is better than the temperature change of the mounting target. The fact is that it appears late.

  In particular, load sensors can be attached in directions that are easily stretched and those that are not, due to their own structure and the structure of the connecting part to the peripheral members. It takes time to expand and contract until the mounting target has been deformed into the shape corresponding to the temperature after the change, and reaches the thermal equilibrium state, and the load sensor output fluctuations with respect to the temperature change of the mounting target Will be late.

  Therefore, load sensor output fluctuations due to temperature drift can be accurately corrected based on the ambient temperature of the load sensor, but load sensor output fluctuations due to expansion and contraction of the mounting target are accurate based on the temperature of the mounting target. It cannot be corrected well.

  Here, as one of the sources of temperature drift that fluctuates the output of the load sensor and the temperature change that causes expansion and contraction of the mounting target, the meshing of the gear of the differential case connected to the most popular axle shaft as the mounting target of the load sensor It is said that the differential heat does not drop easily even after the vehicle is stopped when the load weight is calculated using the load sensor.

  This means that the state in which the output of the load sensor fluctuates due to expansion and contraction due to the temperature change of the mounting target may continue for a considerable period of time, and then it cannot be accurately corrected based on the temperature of the mounting target. However, the load weight is not easily calculated by easily ignoring the output variation of the load sensor due to the expansion / contraction of the mounting target.

  When attaching a load sensor to the axle shaft, lay out the load sensor on the axle shaft portion located on the load transmission path from the connection point with the leaf spring to which the load from the loading platform side is applied to the wheel (tire). Therefore, the presence of brake heat cannot be ignored as a source of a temperature change that causes the output of the load sensor to fluctuate and a temperature change that causes expansion and contraction of the mounting target.

  Unlike the differential heat, this brake heat is said to drop as soon as the vehicle stops and the brake operation is stopped, so the period during which the output of the load sensor fluctuates due to expansion and contraction due to the temperature change of the installation target caused by the brake heat Is shorter than the case of differential heat, and at first glance, it seems that the output fluctuation component of the load sensor due to it can be ignored.

  However, if it is easily affected by brake heat, the amount of temperature change of the mounting target and the amount of expansion / contraction of the mounting target will increase, and the output fluctuation amount of the load sensor will also increase. Even if the output variation period of the load sensor is short because of its reduced nature, the output variation amount of the load sensor due to the expansion and contraction of the mounting object that appears late with respect to the temperature change of the mounting object does not fall within a negligible volume.

  From the above, in order to accurately calculate the vehicle load weight from the output of the load sensor, it is very important to compensate for the fluctuation component that appears in the output of the load sensor through expansion and contraction due to the temperature change of the mounting target. It becomes.

  On the other hand, the conventional temperature compensation method for linearly correcting the output of the load sensor at that time by obtaining the temperature change amount of the ambient temperature of the load sensor with respect to the reference temperature is the change of the ambient temperature of the load sensor. It is effective for compensation for temperature drift of a load sensor that follows in real time, but it is effective for compensation for fluctuation components that appear in the output of the load sensor through expansion and contraction of the mounting target that does not follow the temperature change of the mounting target in real time. It's hard to say.

  In addition, the expansion and contraction characteristics associated with changes in the temperature of the mounting target vary depending on the type of axle shaft material, shape, structure, etc., and the output of the load sensor accompanying the expansion and contraction of the mounting target with respect to the temperature change of the mounting target. How the fluctuations appear late varies depending on the vehicle type and the difference is large, so there is a method and means that can easily and effectively compensate for the fluctuation component that appears in the output of the load sensor through the expansion and contraction of the mounting object. The current situation is that it does not exist.

  The present invention has been made in view of the above circumstances, and the object of the present invention is to determine the current temperature of the mounting target or the past even when the output of the load sensor does not change without time difference following the temperature change of the mounting target. The vehicle load weight calculation method capable of accurately calculating the load weight of the vehicle by accurately compensating the output of the load sensor from the temperature change tendency of the vehicle, and a vehicle suitable for use in carrying out this method. It is to provide a load weight calculation device.

The present invention of claim 1, wherein to achieve the object is related to load calculating method for a vehicle, the present invention of claim 2 Symbol mounting relate load calculating device for a vehicle.

The load weight calculation method for a vehicle according to the first aspect of the present invention is the load signal output by a strain detection type load sensor attached to the vehicle with a physical quantity corresponding to the load of the vehicle while the vehicle is stopped. F is corrected by a temperature linear correction coefficient m for temperature drift correction determined in accordance with a drift amount with respect to a reference temperature of the temperature at the mounting position of the load sensor measured by the temperature sensor, and the vehicle is based on the corrected load signal. In calculating the load weight of the load sensor, the fixed time at the mounting position of the load sensor calculated from two outputs before and after the elapse of a fixed time among the outputs of the temperature sensor periodically sampled after the vehicle stops Of the temperature change amount before and after the elapse of time and the load signal periodically sampled from the load sensor after the vehicle stops, The temperature straight line at which the value of the corrected load signal corresponding to the load signal from the load sensor sampled at the same timing as the output of the temperature sensor has a proportional relationship after the lapse of the predetermined time. The correction coefficient and the time zone after the vehicle stops are obtained from the output of the load sensor and the output of the temperature sensor after the vehicle stops, and the predetermined time elapses of the temperature sensor in the obtained time zone. From the two outputs before and after and the value of the corrected load signal after the lapse of the predetermined time corresponding to the load signal sampled from the load sensor at the same timing as the output of the temperature sensor after the lapse of the predetermined time , The proportional coefficient between the temperature change amount before and after the lapse of the fixed time and the corrected load signal after the lapse of the fixed time and the temperature direct After obtaining a correction coefficient in advance and obtaining the proportionality coefficient and the temperature linear correction coefficient, the temperature before and after the fixed time elapse of the load sensor mounting location from two outputs before and after the fixed time elapse of the temperature sensor. After calculating the amount of change and determining the proportionality coefficient and the temperature linear correction coefficient, the amount of temperature change before and after the lapse of the predetermined time at the load sensor mounting location in the time zone after the vehicle stops And the physical quantity change conversion amount of the corrected load signal after the lapse of the predetermined time from the previously obtained proportionality coefficient and temperature linear correction coefficient, and the calculated in the time zone after the vehicle stops Based on the physical quantity change conversion amount of the corrected load signal after the lapse of the certain time, the load sensor supports the same timing as the output of the temperature sensor after the lapse of the certain time. The corrected load signal or the corrected load signal using the obtained temperature linear correction coefficient after the lapse of the predetermined time corresponding to the load signal is corrected, and the corrected load signal or the corrected signal is corrected. The load weight of the vehicle is calculated based on the load signal corrected using the obtained temperature linear correction coefficient after the predetermined time has elapsed.
It is characterized by that.

  In addition, as shown in the basic configuration diagram of FIG. 1, the load weight calculation device for a vehicle according to the second aspect of the present invention includes a strain detection type load sensor 11 attached to the vehicle while the vehicle is stopped. A load signal output as a physical quantity corresponding to the load of the vehicle is corrected by a temperature linear correction coefficient for temperature drift correction determined according to a drift amount with respect to a reference temperature of the temperature at the mounting position of the load sensor 11 measured by the temperature sensor 13a. A vehicle load weight calculation device for calculating the load weight of the vehicle based on the corrected load signal, wherein a predetermined time out of outputs of the temperature sensor 13a periodically sampled after the vehicle stops. Calculated from two outputs before and after the lapse of time, the temperature change amount before and after the lapse of the fixed time at the mounting position of the load sensor 11, and the load sensor after the vehicle stops Among the load signals periodically sampled from 1, the predetermined time elapse corresponding to the load signal from the load sensor 11 sampled at the same timing as the output of the temperature sensor 13a after the predetermined time elapses The corrected value of the load signal later has a proportional relationship with the temperature linear correction coefficient and the time zone after the vehicle stops, the output of the load sensor 11 after the vehicle stops, and the From the output of the temperature sensor 13a, the load is output at the same timing as the two outputs before and after the fixed time elapses of the temperature sensor 13a and the output of the temperature sensor 13a after the fixed time elapses. The one obtained in advance from the value of the corrected load signal after the lapse of the predetermined time corresponding to the load signal sampled from the sensor 11. Proportional coefficient storage means 17A in which the proportionality coefficient between the temperature change amount at the mounting position of the load sensor 11 before and after the passage of time and the value after the fixed time of the corrected load signal and the temperature linear correction coefficient are stored, A temperature change amount calculating means 21A for calculating a temperature change amount before and after the lapse of the predetermined time at the attachment position of the load sensor 11 from two outputs before and after the lapse of the predetermined time of the temperature sensor 13a, and the post-stop of the vehicle The temperature change amount before and after the lapse of the fixed time calculated by the temperature change amount calculating means 21A calculated by the temperature change amount calculating means 21A, the proportional coefficient and the temperature stored in the proportional coefficient storage means 17A. A physical quantity change conversion amount calculating means 21B that calculates a physical quantity change conversion amount of the corrected load signal after the fixed time elapses from a linear correction coefficient; And using the temperature straight line correction coefficient stored in the proportional coefficient storage means 17A after the fixed time calculated by the physical quantity change conversion amount calculation means 21B in the calculated time zone after the vehicle stops. The load signal sampled from the load sensor 11 at the same timing as the output of the temperature sensor 13a after the lapse of the predetermined time, or the predetermined time corresponding to the load signal, according to the physical quantity change conversion amount of the corrected load signal. The corrected load signal is corrected using the temperature linear correction coefficient stored in the proportional coefficient storage means 17A after the lapse, and the corrected load signal or the proportional coefficient after the fixed time has elapsed after the correction. The load weight of the vehicle is calculated based on the load signal corrected using the temperature linear correction coefficient stored in the means 17A.

  According to the vehicle load weight calculation method of the present invention described in claim 1 and the vehicle load weight calculation apparatus of the present invention described in claim 2, the vehicle load weight calculation apparatus according to the present invention described in claim 2 The load signal sampled from the load sensor is subjected to temperature straight line correction using a temperature straight line correction coefficient corresponding to the drift amount of the temperature at the load sensor mounting location measured by the temperature sensor with respect to the reference temperature. When compensating for the fluctuation component of the load signal due to the expansion and contraction of the load sensor mounting location that does not follow the temperature change and appears late, the fluctuation component of the load signal is constant from the sampling timing of the load signal. A component that is proportional to the amount of change in temperature, which is the amount of change in the output of the temperature sensor at two timings of the timing that goes back in time, and the other, The temperature linear correction coefficient value is determined so that the latter component is included, and the former component is divided into components proportional to the drift amount of the load sensor mounting location at the load signal sampling timing relative to the reference temperature. The load signal obtained by correcting the temperature change amount before and after the elapse of a certain time at the load sensor mounting position and the load signal of the load sensor after the elapse of a certain time with a temperature linear correction coefficient in a predetermined time zone after the vehicle stops Therefore, the temperature of the mounting location of the load sensor can be calculated from the load signal of the load sensor and the output of the temperature sensor at a point in time after a certain period of time has elapsed in advance after the vehicle stops. The load sensor compensates for the drift with respect to the reference temperature and the fluctuation component of the load signal that appears late without following the temperature change at the load sensor mounting location. It can accelerate the time that can calculate an accurate carrying weight by the load signal.

  In the vehicle load weight calculation method of the present invention described in claim 1 and the vehicle load weight calculation apparatus of the present invention described in claim 2, the amount of change in temperature before and after the elapse of a fixed time at the load sensor mounting location. As for the temperature change amount before and after the lapse of a certain time at the load sensor mounting location calculated every predetermined cycle, the moving average temperature change amount for the past consecutive number of times from the latest is used, or the corrected load after the lapse of a certain time As the signal value, it is also possible to use a moving average value for a predetermined number of consecutive times from the latest corrected load signal calculated at each load signal sampling period.

  And if it does in that way, a temporary fluctuation | variation will arise by factors, such as disturbance, in the temperature of the attachment location of the load sensor 11 which the temperature sensor 13a measures, or it will be temporarily in the loading weight of the vehicle which the load sensor 11 measures. Even if the fluctuation is caused by a factor such as a disturbance, it is possible to prevent the calculated vehicle loading weight from greatly blurring due to the influence of the fluctuation.

  By the way, as the amount of temperature change before and after the fixed time elapse of the load sensor mounting location, the temperature change amount before and after the fixed time elapse of the load sensor mounting location calculated every predetermined period is moved from the latest to the past a predetermined number of times. In the case where the average temperature change amount is used, in the vehicle load weight calculation apparatus according to the present invention described in claim 2, the physical quantity change conversion amount calculation unit 21B is configured to calculate the temperature in the obtained time zone after the vehicle stops. There is a temperature change moving average amount calculating means 21C for calculating a moving average temperature change amount for a plurality of past consecutive times of the temperature change amount before and after the fixed time elapse of the attachment position of the load sensor 11 calculated by the change amount calculating means 21A. The temperature change moving average amount calculation means 21C calculates the one of the attachment points of the load sensor 11 in the calculated time period after the vehicle stops. Change in physical quantity of the corrected load signal after elapse of the predetermined time from the moving average temperature change amount of the past continuous multiple times of the temperature change amount before and after the elapse of time and the proportional coefficient stored in the proportional coefficient storage means 17A. This constitutes a vehicle load weight calculation device for calculating the conversion amount.

  Further, when a moving average value for a predetermined number of times in the past from the latest of the corrected load signal calculated at each load signal sampling period is used as the value of the corrected load signal after a predetermined time has elapsed, In the vehicle load weight calculation apparatus of the present invention described above, or in the vehicle load weight calculation apparatus in which the physical quantity change conversion amount calculation means 21B includes the temperature change moving average amount calculation means 21C, the stop of the vehicle In the later obtained time zone, the temperature sensor 13a after the lapse of the predetermined time is corrected by the physical quantity change conversion amount of the corrected load signal after the lapse of the fixed time calculated by the physical quantity change conversion amount calculation means 21B. The load signal sampled from the load sensor 11 at the same timing as the output of the load, or the fixed time corresponding to the load signal As the corrected load signal after the past, the moving average value for the past consecutive predetermined number of times from the latest of the load signal, or the predetermined time elapsed corresponding to the moving average value for the past consecutive predetermined number of times from the latest of the load signal A vehicle load weight calculation apparatus that uses a moving average value for a predetermined number of consecutive times from the latest of the corrected load signal later is configured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is an explanatory diagram showing a schematic configuration of a vehicle load weight calculation apparatus according to an embodiment of the present invention to which the vehicle load weight calculation method of the present invention is applied, and the vehicle load weight calculation apparatus according to the present embodiment. Are six sensor units 10,..., 10 attached to an axle shaft (not shown) corresponding to six wheels (not shown) of the front 1 axis and the rear 2 axes, and a vehicle cabin (not shown). And a main unit 20 that calculates and displays the vehicle load weight from the outputs of the six sensor units 10,..., 10 and each sensor unit 10,. Connected by line 30.

  Each sensor unit 10 uses a strain gauge type load sensor 11 that outputs a load signal F having a frequency (corresponding to a physical quantity in the claims) according to the vehicle load, and a temperature signal from a built-in temperature sensor 13a. The custom IC 13 that corrects the temperature signal linearly for the load signal F output from the sensor 11, the V / F conversion circuit 15 that performs frequency-voltage conversion on the load signal F1 that has been temperature linearly corrected by the custom IC 13, and the V / F conversion circuit 15 output. The one-chip microcomputer (hereinafter abbreviated as “μCOM”) 17 and μCOM 17 to which the load signal F 1 after frequency-voltage conversion and the temperature signal of the temperature sensor 13 a output from the custom IC 13 are input are connected to the bus line 30. Input / output interface (hereinafter abbreviated as “I / F”) 19, and these load sensors 11, custom IC 1 3. A power supply circuit P that supplies operating power to the V / F conversion circuit 15, the μCOM 17, and the I / F 19 is provided.

  The custom IC 13 has a circuit for performing linear correction according to the ambient temperature detected by the temperature sensor 13a on the load signal F output from the load sensor 11 using the temperature linear correction coefficient m. It is incorporated together with the sensor 13a.

  The μCOM 17 incorporates an EEPROM (all not shown) in addition to the CPU, RAM, and ROM. Among these, the EEPROM (corresponding to the proportional coefficient storage means 17A in the claims) has a temperature change amount correction function. The coefficient a (corresponding to the proportional coefficient in the claims), the temperature linear correction coefficient m, and the reference temperature described above are stored.

  The temperature straight line correction coefficient m stored in the EEPROM is an actual temperature shift amount with respect to the reference temperature for canceling the temperature drift of the load sensor 11 due to a temperature change, as in the conventional temperature compensation. Accordingly, it is used for temperature linear correction for correcting the load signal F output from the load sensor 11, and the CPU of the μCOM 17 changes variously from the load sensor 11 attached to the axle shaft without loading and unloading when the vehicle is stopped. The relationship of the variation amount of the load signal F with respect to the temperature variation amount T from the reference temperature (variation amount of the load signal F / temperature variation amount T from the reference temperature) obtained from the load signal F actually sampled at various temperatures is shown. It is a coefficient.

  Incidentally, the temperature linear correction coefficient m is a load signal with respect to the temperature change amount T from the reference temperature, which is obtained in advance from the load signal F actually sampled at various temperatures for the load sensor 11 before being attached to the axle shaft. It can also be determined from the relationship of the fluctuation amount of F (the fluctuation amount of the load signal F / the temperature change amount T from the reference temperature) and can be fixedly set in the circuit of the custom IC 13.

  However, in the vehicle load weight calculation apparatus according to the present embodiment, the CPU of the μCOM 17 actually loads samples sampled at various temperatures from the load sensor 11 attached to the axle shaft without loading / unloading the load when the vehicle is stopped. From the signal F and the temperature change amount T from the reference temperature of the temperature at the time of sampling the load signal F indicated by the temperature signal sampled by the CPU of the μCOM 17 from the temperature sensor 13a, it is obtained by the CPU of the μCOM 17 and stored in the EEPROM. The

  Since the temperature change amount T of the load sensor 11 varies depending on the individual load sensors 11, the above-described temperature linear correction coefficient m is obtained for each load sensor 11 and stored individually in the EEPROM. Alternatively, it is set to the circuit of the custom IC 13 of the sensor unit 10 having the load sensor 11.

  Further, in this embodiment, the reference temperature required for obtaining the temperature change amount T is set to 25 ° C. for each sensor unit 10, and this is also stored in the EEPROM or each sensor unit 10. It is set to the circuit of the custom IC 13 of the unit 10.

In the circuit of the custom IC 13 of each sensor unit 10, the load signal F1 after the temperature linear correction using the temperature linear correction coefficient m is expressed by the following equation:
F1 = F + m × T
And output to the V / F conversion circuit 15 in the subsequent stage.

  The temperature change amount correction coefficient a stored in the EEPROM is obtained when the load signal F of the load sensor 11 fluctuates due to shrinkage accompanying a temperature change of an axle shaft (not shown) to which the sensor unit 10 having the load sensor 11 is attached. This is a coefficient used for temperature change correction to compensate for a delay in follow-up of fluctuations in the load signal F with respect to temperature changes of the axle shaft.

  That is, when a temperature change occurs in the vicinity of the load sensor 11, the portion where the axle shaft load sensor 11 (sensor unit 10) to which the temperature change is transmitted also changes in temperature, and the load sensor 11 (sensor Expansion and contraction occurs in the axle shaft portion to which the unit 10) is attached, and a variation due to the expansion and contraction occurs in the load signal F of the load sensor 11.

  Since the thermal deformation speed of the axle shaft is slower than the heat transfer speed, the expansion and contraction of the axle shaft portion to which the load sensor 11 is attached does not fluctuate following the temperature change of the axle shaft portion. Appears late with respect to temperature changes.

  Therefore, correction for improving the followability of fluctuation of the load signal F with respect to the temperature change of the axle shaft portion to which the load sensor 11 is attached is performed by temperature change amount correction using the temperature change amount correction coefficient a.

  This temperature change amount correction coefficient a is a temperature sensor of the custom IC 13 that is sampled periodically (for example, every 0.25 to 0.5 sec) by the CPU of the μCOM 17 in a state where no cargo is loaded or unloaded when the vehicle is stopped. The difference between the two sampling values of the output 13a before and after the lapse of a certain time, that is, the temperature change ΔT, and the load sensor 11 attached to the axle shaft by the CPU of the μCOM 17 are actually periodically (for example, 0.25 to 0). The load signal F sampled at the same timing as the output after the lapse of a fixed time in the two outputs used for obtaining the temperature change ΔT among the sampled load signals F every 5 sec) The load signal F1 after straight line correction and the load signal F3 after frequency-voltage conversion by the V / F conversion circuit 15 have a proportional relationship. The when filled, a coefficient indicating a ratio of the two F3 / [Delta] T.

  Here, how the load signal F3 after frequency-voltage conversion of the load signal F1 after the temperature straight line correction described above is subjected to frequency-voltage conversion and the temperature change amount ΔT determine how to have a proportional relationship. I will explain.

  First, as described above, the vehicle stops due to the delay in the follow-up of the change in the load signal F (the expansion and contraction of the axle shaft portion) with respect to the temperature change of the axle shaft portion to which the load sensor 11 (sensor unit 10) is attached. As shown in the graph of FIG. 3 showing the time change of the temperature of the axle shaft portion where the load sensor 11 is attached and the frequency of the load signal F with the time point being zero, the temperature of the axle shaft portion where the load sensor 11 is attached is shown. The change in the frequency of the load signal F with respect to the change does not have a proportional relationship.

  Therefore, when the amount of change in temperature of the axle shaft portion to which the load sensor 11 is attached, which is represented by the temperature signal of the temperature sensor 13a, that is, the amount of change in temperature ΔT is obtained before and after the passage of an arbitrary time, the amount of change in temperature ΔT is The load signal F represented by the frequency of the load signal F of the load sensor 11 after the lapse of the arbitrary time does not have any proportional relationship as shown by a one-dot chain line in the graph of FIG.

  However, when an appropriate value is set as the above-described temperature linear correction coefficient m used to correct the frequency of the load signal F of the load sensor 11 in accordance with the temperature drift amount T of the load sensor 11, the figure is displayed after the vehicle stops. As indicated by the solid line in the graph of FIG. 4, the temperature change amount ΔT has a proportional relationship with the load signal F1 after the temperature signal is corrected by the temperature linear correction coefficient m set to an appropriate value. Then, there is a time zone that falls within an acceptable allowable range.

  Eventually, this does not follow the temperature change of the axle shaft portion to which the load sensor 11 is attached, and therefore appears at a delay with respect to the change of the temperature signal of the temperature sensor 13a. The amount of change in the temperature signal of the temperature sensor 13a at two timings, ie, the timing at which the load signal changes due to expansion and contraction, the timing at which the load signal is sampled, and the timing that precedes it by an arbitrary time interval Δt Is divided into a component that is proportional to ΔT and a component that is proportional to the drift amount of the temperature of the axle shaft portion to which the load sensor 11 is attached at the load signal sampling timing relative to the reference temperature. Means that you can.

  Therefore, the value of the temperature linear correction coefficient m is determined so as to include the latter component, and the former component is obtained as the temperature variation correction coefficient a.

  Specifically, this temperature change amount correction coefficient a is after the time interval Δt of the load signal F1 after temperature linear correction, which can be considered to have a proportional relationship with the temperature change amount ΔT shown in FIG. The value of the load signal F3 after frequency-voltage conversion by the V / F conversion circuit 15 and the same timing as the load signal F1 of the load sensor 11 and its arbitrary time The temperature change, which is the amount of change in the temperature signal of the temperature sensor 13a, before and after the time interval Δt (corresponding to a certain time in the claim) sampled at the timing before the passage (corresponding to the certain time in the claim) It is obtained from the ratio F3 / ΔT of the quantity ΔT.

  The time interval Δt is equal to the period at which the CPU of the μCOM 17 samples the load signal F from the load sensor 11 or the same period at which the temperature signal is sampled from the temperature sensor 13a of the custom IC 13 (for example, 0.25 to 0.25). Considerably longer than a period (for example, every 0.5 to 1 sec) in which the display of the vehicle weight calculated using those values is updated in the main unit 20 described later. (For example, in units of several minutes).

The load signal F5 after temperature change correction (and after temperature straight line correction) using the temperature change correction coefficient a is calculated by the following equation:
F5 = F3 + a × ΔT
Sought by.

  Incidentally, the time zone in which the load signal F1 corrected by the temperature linear correction coefficient m and the temperature change amount ΔT have a proportional relationship is used to determine the temperature change amount ΔT of the axle shaft portion to which the load sensor 11 is attached. Regardless of the length of the time interval Δt, the temperature variation correction coefficient a at that time increases as the time interval Δt decreases.

  Further, the variation of the load signal F accompanying the variation of the temperature of the axle shaft portion to which the load sensor 11 is attached varies depending on the individual load sensor 11 with respect to the variation caused by the temperature drift, and the load sensor 11 is attached. Also, the fluctuation caused by the expansion and contraction of the axle shaft portion is caused by the structure of the axle shaft portion to which the load sensor 11 is attached, in other words, due to the structure of the axle shaft itself and the structure of the connecting portion to the peripheral member. Has its own trend.

  Therefore, the temperature linear correction coefficient m and the temperature change correction coefficient a are individually determined by the procedure described above for each load sensor 11.

In addition, the sampling of the load signal F of the load sensor 11 and the temperature signal of the temperature sensor 13a is performed without changing the loaded weight after the vehicle stops (1) normal (for example, 0.25 to 0.5 sec), (2) The frequency of the corrected load signal F1 obtained by performing the temperature linear correction by the temperature linear correction coefficient m and the temperature signal of the temperature sensor 13a are respectively performed in three cycles of normal + 60% and (3) normal -30%. The relationship with the temperature change amount ΔT before and after the time interval Δt was confirmed, and the result is shown in the graph of FIG. 5 (the thin line in FIG. 5 represents the frequency of the corrected load signal F1 in (1) to (3)). The relationship with the temperature change amount ΔT, the thick line indicates the moving average temperature change amount ΔT _ave obtained by moving average of the frequency of the corrected load signal F1 and the latest five temperature change amounts ΔT obtained every predetermined period, for example, 60 _seconds. Relationship).

As shown in FIG. 5, in any of the above sampling cycles (1) to (3), the value of the temperature change amount ΔT (the moving average temperature change amount ΔT _ave ) once increases to zero. Among the changes in the time series that decrease toward the temperature, the temperature change amount ΔT (the moving average temperature change amount ΔT _ave ) and the frequency of the corrected load signal F1 that has been subjected to the temperature linear correction by the temperature linear correction coefficient m, There is a region that can be seen as having a proportional relationship.

  Incidentally, the sampling of the load signal F of the load sensor 11 and the temperature signal of the temperature sensor 13a is performed without changing the loaded weight after the vehicle stops (1) normal (for example, 0.25 to 0.5 sec), (2) Normal + 60%, (3) Normal -30%, and for each of them, a corrected load signal F1 obtained by performing temperature linear correction with the temperature linear correction coefficient m is obtained once, and further its frequency-voltage conversion When the post-correction load signal F5 obtained by subjecting the subsequent load signal F3 to the temperature change amount correction by the temperature change amount correction coefficient a was obtained, the following results were obtained.

  That is, after frequency-voltage conversion is performed on the load signal F1 of the load sensor 11 after the temperature linear correction sampled at a normal cycle, as shown in the graph of FIG. The load weight W3 of the vehicle calculated by the load signal F3 is substantially saturated and stable around 30 minutes after the vehicle stops, but the load signal F3 after the correction is performed by correcting the temperature change amount to the load signal F3. The vehicle loading weight W5 (1) to (3) calculated by F5 is already almost saturated and stable at about 15 minutes after the vehicle stops at any of the sampling periods of (1) to (3) described above. .

  Accordingly, the temperature change amount correction by the temperature change amount correction coefficient a is added to the frequency-voltage converted load signal F3 of the corrected load signal F1 subjected to the temperature linear correction by the temperature linear correction coefficient m. The time interval described above is used to determine the temperature change amount ΔT of the axle shaft portion to which the load sensor 11 is attached, so that the correction for improving the followability of the fluctuation of the load signal F with respect to the change in the ambient temperature of the load sensor 11 It can be seen that this is done without depending on Δt.

  Note that a method for calculating the load weight W5 of the vehicle shown in the graph of FIG. 6 from the load signal F5 after temperature linear correction, frequency-voltage conversion, and temperature change correction of the load sensor 11 is a main unit described later. The method of calculating the load weight W3 of the vehicle from the load signal F3 after frequency-voltage conversion of the load signal F1 after the temperature linear correction of the load sensor 11 is also calculated. The method is basically the same.

  In the main unit 20, which will be described later, temperature linear correction of the load sensor 11, frequency-voltage conversion, calculation of the load signal F5 after temperature change amount correction, and calculation of the vehicle loading weight W5 using the load signal F5. However, as shown in the graph of FIG. 5, the calculated load weight W5 is saturated and unstable until 15 minutes after the vehicle stops, so that 15 minutes after the vehicle stops. A period corresponding to the elapsed time is stored in advance in the EEPROM of each sensor unit 10 as an idling time t for prohibiting the calculation of the loaded weight.

  The time from when the vehicle stops until the load weight W5 calculated from the load signal F5 after the temperature linear correction, frequency-voltage conversion and temperature change correction of the load sensor 11 is saturated and stabilized is the load Since each load sensor 11 varies depending on the characteristics of the sensor 11 itself and the structure of the mounting location of the axle shaft, the EEPROM of each sensor unit 10 includes temperature linear correction, frequency-voltage conversion, and The time from when the vehicle stops until the load weight W5 calculated from the load signal F5 after the temperature change correction is saturated and stabilized is stored as an idling time t unique to the load sensor 11 (sensor unit 10). .

  Incidentally, the time interval Δt is uniquely determined by the value of the temperature change correction coefficient a. Therefore, if only the value of the temperature change correction coefficient a is stored, a value unique to the load sensor 11 (sensor unit 10). As described above, it is not necessary to store the time interval Δt in the EEPROM of each sensor unit 10 separately from the value of the temperature change amount correction coefficient a.

  The CPU of the μCOM 17 incorporating the EEPROM storing the temperature change amount correction coefficient a, the temperature linear correction coefficient m, the reference temperature, and the idling time t determined as described above, In accordance with the control program stored in the ROM, processing as shown in the flowchart of FIG. 7 is performed.

  First, it is confirmed whether or not the collection request data targeting the self from the bus line 30 is input via the I / F 19 (step S1). If input (Y in step S1), the RAM shift is performed. The latest frequency-voltage converted load signal F3 after the temperature linear correction of the load sensor 11 taken in from the V / F conversion circuit 15 of the past multiple times buffered in the register, and stored in the RAM in association therewith. The temperature change amount ΔT of the latest temperature sensor 13a and the temperature change correction coefficient a stored in the EEPROM are returned to the bus line 30 (step S3), and the process returns to step S1.

  On the other hand, when the collection request data is not input (N in step S1), the load signal F3 subjected to frequency-voltage conversion after the temperature linear correction of the load sensor 11 is read from the V / F conversion circuit 15, and the temperature The RAM 13 stores periodically the temperature signal of the sensor 13a from the custom IC 13 (step S5), and stores the acquired load signal F3 and the temperature signal for the latest past multiple times corresponding to at least the time interval Δt. Buffering is performed in the time series in the shift register (step S7), and the latest temperature signal of the temperature sensor 13a stored in the shift register and the time interval Δt are sampled before the temperature signal sampling timing and sampled in the shift register. The difference from the stored temperature signal of the past temperature sensor 13a, that is, the temperature change ΔT is obtained. After being stored in the RAM in association with the frequency-voltage converted load signal F3 after the latest temperature linear correction stored in the shift register and the temperature change correction coefficient a stored in the EEPROM (step S9), The process returns to step S1.

  Incidentally, in the process of step S3 that comes from the start of power supply until the time obtained by subtracting the time interval Δt from the idling time t stored in the EEPROM, the process of the latest temperature sensor 13a stored in the RAM is performed. ΔT = 0 is returned to the bus line 30 as the temperature change amount ΔT of the temperature signal.

  The main unit 20 includes a power supply circuit PS that supplies power to the power supply circuit P of each sensor unit 10, a microcomputer that calculates the loading weight of the vehicle based on signals collected from each sensor unit 10 (hereinafter, referred to as “a microcomputer”). (Abbreviated as “microcomputer”.) 21. I / O that connects the idling time t described above, the non-volatile memory NVM in which the weighting coefficient corresponding to the layout of each sensor unit 10 is stored, and the microcomputer 21 to the bus line 30 F23, and a display 25 for displaying the calculated load weight and the like.

  The microcomputer 21 has a CPU, a RAM, and a ROM. Among them, a travel sensor and an ignition switch (not shown) are connected to the CPU in addition to the RAM, the ROM, and the nonvolatile memory NVM.

  And the microcomputer 21 performs the process shown in the flowchart of FIG. 8 according to the control program stored in ROM.

  First, it is confirmed whether or not the vehicle is stopped based on whether or not the input of a travel pulse from a travel sensor (not shown) is stopped and whether or not the ignition switch is in a position other than ON (step S11). If the vehicle is not stopped (N in Step S11), Step S11 is repeated until the vehicle is stopped. If the vehicle is stopped (Y in Step S11), the collection request data is sent to the bus line 30 via the I / F 23. , The latest frequency-voltage converted load signal F3 after the temperature linear correction, and the temperature change amount ΔT of the latest temperature sensor 13a in response to the sent collection request data. The temperature change amount correction coefficient a is received from the bus line 30 via the I / F 23 sequentially to each sensor unit 10 (step S). 3).

  The latest frequency-voltage converted load signal F3 after the temperature straight line correction, the temperature change amount ΔT of the temperature signal of the latest temperature sensor 13a, and the temperature change correction coefficient a are included in each sensor. If received from each unit 10, it is received for each sensor unit 10 unless the received temperature change amount ΔT = 0 (unless the idling time t stored in the EEPROM of the sensor unit 10 has not elapsed). By multiplying the temperature change amount ΔT by the temperature change amount correction coefficient a and adding the frequency-voltage converted load signal F3 after the latest temperature linear correction, the temperature linear correction, frequency-voltage of the load sensor 11 is added. The load signal F5 after conversion and temperature change amount correction is calculated for each sensor unit 10 (step S15).

  Then, the calculated load signal F5 for each sensor unit 10 is multiplied by a weighting coefficient stored in the nonvolatile memory NVM corresponding to each sensor unit 10 and added together. From the total, the load weight = By subtracting the offset value in the case of 0 and multiplying by the weight conversion coefficient, the load weight W is calculated (step S17), the load weight display on the display 25 is updated (step S19), and the process returns to step S11.

  As is clear from the above description, in the vehicle load weight calculation apparatus of the present embodiment, the circuit incorporated in the custom IC 13 together with the temperature sensor 13a corresponds to the temperature linear correction means 13A in the claims, and the μCOM 17 A built-in EEPROM (not shown) corresponds to the proportional coefficient storage means 17A in the claims, and μCOM 17 corresponds to the communication control means 17B in the claims.

  Further, in the vehicle load weight calculation apparatus of this embodiment, step S15 in FIG. 8 is a process corresponding to the temperature change amount calculation means 21A and the physical quantity change conversion amount calculation means 21B in the claims.

  According to the vehicle load weight calculation apparatus of the present embodiment configured as described above, the temperature linear correction by the temperature linear correction coefficient m is performed on the load signal F from the load sensor 11 in the custom IC 13 of each sensor unit 10. Then, after compensating for the temperature drift component included in the load signal F, the microcomputer 21 of the main unit 20 uses the temperature change correction coefficient a for the load signal F3 after the temperature linear correction and frequency-voltage conversion. The temperature change amount is corrected to compensate for the follow-up delay of the load signal F of the load sensor 11 due to the expansion and contraction due to the temperature change at the axle shaft portion where the load sensor 11 is attached. The structure is improved.

  For this reason, the load signal F of the load sensor 11 is earlier than the expansion or contraction of the axle shaft accompanying the temperature change of the axle shaft portion to which the load sensor 11 is attached or the fluctuation of the load signal F of the load sensor 11 is saturated. It is possible to accurately calculate the loading weight W of the vehicle using the.

  In addition, according to the vehicle load weight calculation apparatus of the present embodiment, the value of the temperature change amount correction coefficient a is used to determine the temperature change amount ΔT of the axle shaft portion to which the load sensor 11 is attached. Since it is obtained without depending on the interval Δt, a time zone (= idling time t) in which the load signal F1 corrected by the temperature linear correction coefficient m and the temperature change amount ΔT have a proportional relationship or the above-described time interval Δt can be arbitrarily set. Even in terms of time, the value of the temperature variation correction coefficient a can be easily determined.

As the temperature change amount ΔT before and after the time interval Δt of the load sensor 11 is attached, the moving average temperature change amount ΔT _ave for the latest past predetermined number of times (for example, five times) including the temperature change amount ΔT is used. The temperature variation correction may be performed using the temperature variation correction coefficient a.

Incidentally, in the case of such a configuration, the process in step S9 of the flowchart of FIG. 7 uses the temperature signal of the temperature sensor 13a stored in the shift register of the RAM, and the temperature signal of the latest (current) temperature sensor 13a. The temperature signal of the past temperature sensor 13a sampled before a predetermined cycle time (for example, 60 sec) from the sampling timing of the temperature signal and stored in the shift register, and further before the predetermined cycle time (the latest temperature sensor 13a) The temperature signal of the past temperature sensor 13a sampled and stored in the shift register, for example, 120 seconds before the temperature signal, and a predetermined period before that (for example, 180 seconds before the temperature signal of the latest temperature sensor 13a) Sampled and stored in shift register The temperature signal of the previous temperature sensor 13a and the temperature signal of the past temperature sensor 13a sampled and stored in the shift register by a predetermined period before (for example, 240 seconds before the temperature signal of the latest temperature sensor 13a). For each, a temperature change amount ΔT, which is a difference from the temperature signal of the past temperature sensor 13a sampled by the time interval Δt before each temperature signal and stored in the shift register, is obtained, and the average (moving average) is obtained. ) obtains a moving average temperature variation [Delta] T _ave is, the moving average temperature variation [Delta] T _ave, the frequency after the latest temperature linear correction stored in the shift register - storing voltage converted load signal F3, the EEPROM The content is stored in the RAM in association with the temperature change amount correction coefficient a.

Accordingly, the process in step S3 of the flowchart of FIG. 7 is also performed after the temperature linear correction of the load sensor 11 fetched from the latest V / F conversion circuit 15 among the past multiple times buffered in the RAM shift register. The frequency-voltage converted load signal F3 and the moving average temperature change amount ΔT of the temperature change amount ΔT of the temperature signal of the temperature sensor 13a for the latest past predetermined number of times (for example, five times) stored in the RAM. _The temperature change amount correction coefficient a stored in _ave and EEPROM is returned to the bus line 30.

Similarly, in accordance with this, the temperature change amount ΔT of the temperature signal of the latest temperature sensor 13a in step S13 and step S15 in the flowchart of FIG. 8 is also the past predetermined number of times (for example, five times) every predetermined cycle time including the latest. The moving average temperature change amount ΔT _ave of the temperature change amount ΔT related to the temperature signal of the temperature sensor 13a is respectively replaced.

  When the configuration is changed as described above, the physical quantity change conversion amount calculation means 21B in the claims, as shown in the basic configuration diagram of FIG. 9, the temperature in the determined time zone after the vehicle stops. The temperature change moving average amount calculating means 21C for calculating the moving average temperature change amount for a plurality of past consecutive times of the temperature change amount before and after the fixed time elapse of the attachment position of the load sensor 11 calculated by the change amount calculating means 21A. In other words, step S9 after changing the contents as described above in FIG. 7 is processing corresponding to the temperature change moving average amount calculating means 21C.

Further, the temperature change amount correction by the temperature change amount correction coefficient a is used as the temperature change amount ΔT before and after the time interval Δt of the mounting position of the load sensor 11 or includes the latest. Regardless of whether or not the moving average temperature change amount ΔT _ave of the temperature change amount ΔT related to the temperature signal of the temperature sensor 13a for the past predetermined number of times (for example, five times) every predetermined cycle time, the temperature linear correction after the time interval Δt has elapsed. Calculated for each sampling period of the load signal F from the load sensor 11 as the value of the subsequent load signal F1 (actually, the value of the load signal F1 after the temperature linear correction is frequency-voltage converted) The moving average value F1 _ave (actually, the load after the temperature straight line correction) of the corrected load signal F1 after the temperature straight line correction by the temperature straight line correction coefficient m to be performed is performed for a predetermined number of times in the past. The temperature change amount correction by the temperature change amount correction coefficient “a” is performed using the moving average value F3 _ave ) of the load signal F3 after the frequency-voltage conversion of the signal F1 for the past continuous predetermined number of times. Also good.

Incidentally, in the case of such a configuration, following step S7 of the flowchart of FIG. 7, as shown in the flowchart of FIG. 10, the latest (taken from the V / F conversion circuit 15 stored in the RAM shift register ( The current predetermined number of times including the frequency-voltage converted load signal F3 after the temperature linear correction of the load sensor 11 (for example, 5 times = the latest sampling amount, the sampling amount before 0.25 to 0.5 sec from the latest) , Moving average value F3 _ave of sampling from 0.5 to 1.0 sec before, sampling from 0.75 to 1.5 sec from the latest, sampling from 1.0 to 2.0 sec from the latest) The process of step S8 to be obtained is added, and in the subsequent step S9, the moving average value _F3ave obtained in step S8 is converted into the temperature change amount Δ obtained here. The contents are stored in the RAM in association with T (or the moving average temperature change amount ΔT _ave ) and the temperature change amount correction coefficient a stored in the EEPROM.

Accordingly, the processing in step S3 of the flowchart of FIG. 7 is also performed after the temperature linear correction of the load sensor 11 fetched from the V / F conversion circuit 15 for the past plural times, which is buffered in the RAM shift register− The moving average value F3 _{ave of the} voltage-converted load signal F3 and the temperature change amount ΔT of the latest temperature signal of the temperature sensor 13a stored in the RAM in association therewith (or the past predetermined number of times for each predetermined cycle time including the latest) The moving average temperature change amount ΔT _ave of the temperature change amount ΔT related to the temperature signal of the temperature sensor 13a for 5 minutes (for example, 5 times) and the temperature change amount correction coefficient a stored in the EEPROM are returned to the bus line 30. It will change to the content.

Similarly, the frequency-voltage converted load signal F3 after the latest temperature linear correction in step S13 and step S15 in the flowchart of FIG. 8 is also associated with the load signal sampling cycle of the load sensor 11 including the latest. The moving average value _F3ave of the frequency-voltage converted load signal F3 after the temperature straight line correction for the past predetermined number of times (for example, five times) is respectively replaced.

The temperature change amount ΔT related to the temperature signal of the temperature sensor 13a and the load signal F1 after the temperature linear correction of the load sensor 11 (the load signal F3 after frequency-voltage conversion of the value of the load signal F1 after the temperature linear correction) Is replaced with a moving average temperature change amount ΔT _ave or a moving average value F3 _{ave obtained} by moving average, the temperature sensor 13a measures the temperature at the location where the load sensor 11 is mounted, and the temporal fluctuations are disturbances or the like. Even if temporary fluctuations occur in the vehicle loading weight measured by the load sensor 11 due to factors such as disturbances, the calculated vehicle loading weight greatly fluctuates due to the influence of such fluctuations. Can be prevented.

  Further, in the present embodiment, since the temperature straight line correction by the temperature straight line correction coefficient m for the load signal F from the load sensor 11 is performed in the custom IC 13, the temperature change amount correction by the temperature change amount correction coefficient a is performed later. The temperature change amount correction by the temperature change amount correction coefficient a for the load signal F from the load sensor 11 is performed first, and the temperature linear correction by the temperature linear correction coefficient m is performed by the main unit 20 instead of the custom IC 13. The microcomputer 21 may be configured by logic.

  Further, the temperature of the axle shaft portion to which the load sensor 11 is attached may be measured by a temperature sensor in the vicinity of the axle shaft installed separately from the sensor unit 10, but the temperature linear correction by the temperature linear correction coefficient m is performed. If the configuration as in the present embodiment in which the ambient temperature of the load sensor 11 is measured by the temperature sensor 13a of the custom IC 13 on the premise that the load sensor 11 is performed first, the location closer to the axle shaft location to which the load sensor 11 is attached. This is advantageous because the temperature can be measured and the calculation accuracy of the load weight W can be improved.

  In the present embodiment, the sensor unit 10 is provided with a μCOM 17, and the load signal F3 after the temperature linear correction and frequency-voltage conversion and the temperature signal of the temperature sensor 13a are once fetched into the sensor unit 10 to obtain the latest temperature signal of the temperature sensor 13a. The temperature change amount ΔT is calculated on the sensor unit 10 side and then output to the microcomputer 21 of the main unit 20. However, the μCOM 17 of the sensor unit 10 is omitted, and the microcomputer 21 of the main unit 20 is directly connected to the custom IC 13 or Connected to the V / F conversion circuit 15, the load signal F3 and the temperature signal are taken into the microcomputer 21, and the temperature change amount ΔT of the temperature signal of the latest temperature sensor 13a is calculated on the main unit 20 side. Also good.

  Furthermore, in this embodiment, although the case where the load sensor 11 which outputs the load signal F of the frequency according to the load of a vehicle was used was demonstrated, for example like Unexamined-Japanese-Patent No. 2000-28423, self with a change of a load Even when using a load sensor that obtains an output according to the load by a change in physical quantity other than the frequency according to the change in load, such as when using a sensor that obtains an output according to the load by changing impedance (inductance + loss resistance) The present invention is applicable.

  In this case, the temperature change correction coefficient a stored in the EEPROM is the same timing as the output after the lapse of a fixed time among the outputs of the temperature sensor 13a before and after the lapse of the fixed time used to obtain the temperature change ΔT. The corrected voltage value obtained by performing the temperature linear correction using the temperature linear correction coefficient m on the output sampled from the load sensor, that is, the voltage value corresponding to the physical quantity corresponding to the load, and the temperature change ΔT Is a coefficient indicating the ratio between the two when a condition having a proportional relationship is satisfied.

1 is a basic configuration diagram of a vehicle load weight calculation apparatus according to the present invention. It is explanatory drawing which shows schematic structure of the vehicle load weight calculation apparatus which concerns on one Embodiment of this invention to which the vehicle load weight calculation method of this invention is applied. FIG. 3 is a graph showing temporal changes in the ambient temperature of the load sensor in FIG. 2 and the frequency of the load signal with the vehicle stop point as zero. The relationship between the amount of change in the ambient temperature of the load sensor of FIG. 2, the frequency of the load signal of the load sensor, and the frequency of the load signal after correction of the load signal of the load sensor after the temperature linear correction is performed for an arbitrary sampling period. It is a graph shown respectively. It is a graph which shows the relationship between the variation | change_quantity of the ambient temperature of the load sensor of FIG. 2, and the frequency of the corrected load signal which performed the temperature linear correction | amendment to the load signal of a load sensor, respectively about three different sampling periods. A load signal obtained by adding a temperature linear correction to the load signal from the load sensor shown in FIG. FIG. 5 shows three sampling cycles shown in FIG. 5 for the time fluctuation of the load weight of the vehicle calculated by the frequency-voltage converted value of the load signal to which the temperature linear correction and the temperature change amount correction are added. It is a graph to show. It is a flowchart which shows the process which the one-chip microcomputer of the sensor unit of FIG. 2 performs according to the control program stored in internal ROM. It is a flowchart which shows the process which the microcomputer of the main unit of FIG. 2 performs according to the control program stored in ROM. FIG. 2 is a basic configuration diagram of a vehicle load weight calculation apparatus when the frequency change conversion amount calculation unit of FIG. 1 includes a temperature change moving average amount calculation unit. 9, the one-chip microcomputer of the sensor unit of FIG. 2 executes the processing shown in the flowchart of FIG. 7 in accordance with the control program stored in the internal ROM. It is a flowchart which shows the process to perform.

Explanation of symbols

10 Sensor unit 11 Load sensor 13 Custom IC
13A Temperature linear correction means 13a Temperature sensor 17 μCOM
17A proportional coefficient storage means 17B communication control means 21 microcomputer 21A temperature change amount calculation means 21B physical quantity change conversion amount calculation means

Claims (2)

A reference temperature of the temperature at which the load sensor is mounted, where the temperature sensor measures a load signal F output by a strain detection type load sensor attached to the vehicle in a physical quantity corresponding to the load of the vehicle while the vehicle is stopped. When calculating the weight of the vehicle based on the corrected load signal, the temperature linear correction coefficient m for correcting the temperature drift determined according to the amount of drift with respect to
Of the output of the temperature sensor periodically sampled after the vehicle stops, calculated from two outputs before and after the elapse of a fixed time, the temperature change amount before and after the elapse of the fixed time of the load sensor mounting location, Corresponds to the load signal from the load sensor sampled at the same timing as the output of the temperature sensor after the fixed time has elapsed among the load signals periodically sampled from the load sensor after the vehicle stops. The temperature linear correction coefficient that causes the value of the corrected load signal after the lapse of the predetermined time to have a proportional relationship and the time zone after the vehicle stops are the load sensor after the vehicle stops. And the output of the temperature sensor, the two outputs before and after the lapse of the fixed time of the temperature sensor in the determined time zone, and the fixed time The fixed time of the mounting location of the load sensor from the value of the corrected load signal after the fixed time corresponding to the load signal sampled from the load sensor at the same timing as the output of the temperature sensor after The temperature coefficient before and after the passage of time and the proportional coefficient between the corrected load signal after the lapse of the predetermined time and the temperature linear correction coefficient are obtained in advance
After obtaining the proportionality coefficient and the temperature linear correction coefficient, calculate the amount of temperature change before and after the lapse of the fixed time from the two outputs before and after the fixed time of the temperature sensor,
After obtaining the proportionality coefficient and the temperature straight line correction coefficient, in the time zone after the vehicle stops, the calculated temperature change amount before and after the lapse of the predetermined time at the load sensor mounting position is obtained in advance. From the proportionality coefficient and the temperature linear correction coefficient, calculate the physical quantity change conversion amount of the corrected load signal after the fixed time has elapsed,
The load sensor at the same timing as the output of the temperature sensor after the lapse of the predetermined time, in the time zone after the vehicle stops, according to the calculated physical quantity change converted amount of the corrected load signal after the lapse of the predetermined time. The load signal sampled from the load signal or the load signal corrected using the obtained temperature linear correction coefficient after the lapse of the predetermined time corresponding to the load signal is corrected, and the corrected load signal or correction is corrected. The load weight of the vehicle is calculated based on the load signal corrected using the obtained temperature linear correction coefficient after the predetermined time later.
A vehicle load weight calculation method characterized by the above. A load signal output by a strain detection type load sensor attached to the vehicle with a physical quantity corresponding to the load of the vehicle while the vehicle is stopped is measured with respect to a reference temperature of a temperature at which the load sensor is attached. A vehicle load weight calculation device that corrects by a temperature linear correction coefficient for temperature drift correction determined according to a drift amount, and calculates the load weight of the vehicle based on the corrected load signal,
Of the output of the temperature sensor periodically sampled after the vehicle stops, calculated from two outputs before and after the elapse of a fixed time, the temperature change amount before and after the elapse of the fixed time of the load sensor mounting location, Corresponds to the load signal from the load sensor sampled at the same timing as the output of the temperature sensor after the fixed time has elapsed among the load signals periodically sampled from the load sensor after the vehicle stops. The temperature linear correction coefficient that causes the value of the corrected load signal after the lapse of the predetermined time to have a proportional relationship and the time zone after the vehicle stops are the load sensor after the vehicle stops. And the output of the temperature sensor, the two outputs before and after the lapse of the fixed time of the temperature sensor in the determined time zone, and the fixed time The pre-determined value before and after the elapse of the predetermined time, which is obtained in advance from the value of the corrected load signal after the elapse of the predetermined time, corresponding to the load signal sampled from the load sensor at the same timing as the output of the temperature sensor after Proportional coefficient storage means in which the proportionality coefficient between the temperature change amount of the load sensor mounting location and the value of the corrected load signal after the lapse of the predetermined time and the temperature linear correction coefficient are stored;
A temperature change amount calculating means for calculating a temperature change amount before and after the lapse of the fixed time of the mounting position of the load sensor from two outputs before and after the fixed time of the temperature sensor;
The temperature change amount before and after the lapse of the predetermined time at the load sensor mounting position calculated by the temperature change amount calculation means in the determined time zone after the vehicle stops, and the proportionality stored in the proportionality coefficient storage means A physical quantity change conversion amount calculating means for calculating a physical quantity change conversion amount of the corrected load signal after the fixed time elapses from a coefficient and the temperature linear correction coefficient;
The load signal corrected using the temperature linear correction coefficient stored in the proportional coefficient storage means after the fixed time calculated by the physical quantity change conversion amount calculation means calculated by the physical quantity change conversion amount calculation means after the vehicle has stopped. The load signal sampled from the load sensor at the same timing as the output of the temperature sensor after the lapse of a certain time, or the proportional coefficient after the lapse of the certain time corresponding to the load signal, by a physical quantity change conversion amount The corrected load signal is corrected using the temperature linear correction coefficient stored in the means, and the corrected load signal or the temperature linear correction stored in the proportional coefficient storage means after the fixed time has elapsed after the correction. Calculating the load weight of the vehicle based on the load signal corrected using a coefficient;
A vehicle load weight calculation apparatus characterized by the above.

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