JP2008076225A - Air resistance measuring method and air resistance measuring device - Google Patents

Abstract

To provide an air resistance measuring device capable of obtaining an air resistance in a posture in which a vehicle is traveling at a constant speed and obtaining an air resistance with less error than conventional.
A measuring plate having a length in a traveling direction and a width in a direction orthogonal thereto, which is continuously arranged on a traveling road surface RD and is capable of simultaneously contacting all the wheels FW and RW of a vehicle to be measured TM. The air resistance measuring device includes a measuring unit that measures a tire surface force, which is a force transmitted from the outer peripheral surface of the tire to the measuring plate 2 when the vehicle travels on the plate 2.
[Selection] Figure 1

Description

  The present invention relates to an air resistance measuring method and an air resistance measuring device for measuring an air resistance acting on a vehicle during traveling.

Conventionally, as a method for measuring the air resistance of a vehicle, a method using a wind tunnel experimental facility is well known.
In addition, as a measurement method that does not use this large-scale wind tunnel experimental equipment, a method is known in which the vehicle is placed in a coasting straight state (coast down running) with the engine power cut off, and the resistance acting on the vehicle is measured (for example, Patent Document 1).

This resistance measurement method is performed as follows.
In other words, from a state where the vehicle is running at a constant speed on an actual road, by changing the transmission gear position to neutral or the like, the engine driving force transmitted to the tire is cut off, and a coast down test is performed in which the vehicle goes straight by inertia. Execute. Then, the vehicle travel speed change (ΔV) with respect to the time change (ΔT) at this time is measured, and the total travel resistance of the vehicle is obtained from the vehicle mass and the rotational inertia mass (m) of the vehicle tire or the like.

  This running resistance includes rolling resistance, driving shaft resistance, and air resistance mainly for tires. Therefore, the drive shaft resistance can be obtained as a coast-down running state in a state where the tire is lifted from the road surface by jacking up the vehicle or the like.

  In addition, since the rolling resistance is almost negligible when driving at low vehicle speeds, coasting is performed at low vehicle speeds, and the driving resistance is subtracted from the driving resistance at this time. Find constants and coefficients.

In addition, since air resistance accounts for most of the running resistance during high speed running, coast down running at high speed, from the resistance equation of factors other than the air resistance already obtained and the running resistance data obtained this time, Find the air resistance and its constants and coefficients.
JP-A-8-247903

As described above, conventionally, when the running resistance is obtained, the vehicle is coasted down and obtained.
However, since the vehicle is in a decelerating state during coast down running, the vehicle posture at this time is a forward leaning posture with respect to the vehicle posture in the constant speed running state.

On the other hand, what we want to measure as the air resistance of the vehicle is the air resistance when the engine driving force is transmitted by the tire and running at a constant speed, and the vehicle attitude at this time is the coast down described above. It differs from the forward leaning posture during driving.
For this reason, there is a problem that the air resistance obtained at the time of coasting down is different from the air resistance at the time of actual traveling, and the data obtained based on the air resistance obtained at the time of coasting down also has an error. Cause the problem that occurs.

  The present invention has been made paying attention to the above-mentioned problems, and obtains air resistance in a posture where the vehicle is running at a constant speed, and obtains air resistance with little error from air resistance during actual running. An object of the present invention is to provide an air resistance measurement method and an air resistance measurement device that can perform the above-described process.

  In order to achieve the above-mentioned object, the present invention measures the tire surface force of a vehicle to be measured traveling at a constant speed, and obtains the air resistance of the vehicle to be measured from the tire surface force. The measurement method was used.

In the present invention, the tire surface force during constant speed traveling is measured, and the air resistance is obtained from the tire surface force, so that the most common engine driving force is transmitted to the road surface in the actual traveling state. Air resistance in the running posture can be obtained.
Therefore, the error can be reduced as compared with the case where the air resistance is obtained in the traveling posture in the deceleration state as in the prior art.

Here, a method for calculating the air resistance from the tire outer peripheral surface force will be briefly described.
As shown in the following equation (a), the running resistance of a vehicle running on a real road at a constant speed is a sum of tire rolling resistance, mechanical resistance, and air resistance. Rolling resistance + mechanical resistance + air resistance (a)
The tire rolling resistance is a resistance lost due to tire deformation that occurs when the tire tread surface is in contact with the road surface. The mechanical resistance is a set of resistance caused by axle bearing friction, resistance generated by the disc brake pad and the rotor being naturally struck even when no brake fluid pressure is applied. The air resistance is resistance due to air flow acting on the vehicle body.

  Further, the force transmitted from the tire outer peripheral surface to the road surface is a force obtained by subtracting “tire rolling resistance” and “mechanical resistance” from the force transmitted from the drive shaft to the tire.

Therefore, the tire outer peripheral surface force can be expressed by the following formula (b).
Tire outer surface force = drive shaft force−tire rolling resistance−mechanical resistance (b)

  From the above formulas (a) and (b), the force transmitted from the tire outer peripheral surface to the road surface (this is the tire surface force) is equivalent to “air resistance”.

  In this way, since the total value of the tire surface force in the traveling direction of the vehicle running on the actual road at a constant speed is equivalent to the air resistance of the actual road, the vehicle air resistance is measured by measuring the tire surface force of the vehicle. Can be sought.

  As described above, in the present invention, it is possible to obtain the air resistance when the vehicle is traveling at a constant speed on the actual road. Thus, it is possible to obtain a more accurate air resistance by eliminating an error from the air resistance during traveling.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The air resistance measuring device of this embodiment is arranged continuously on the traveling road surface (RD), and the length of the traveling direction in which all the wheels (FW, RW) of the vehicle to be measured (TM) can simultaneously contact and the orthogonality thereof. A measurement plate (2) having a width in the direction and a tire surface force, which is a force transmitted from the outer peripheral surface of the tire to the measurement plate (2) when the vehicle travels on the measurement plate (2) And an air resistance measuring device characterized by comprising:

  The air resistance measuring apparatus A according to the first embodiment of the present invention and the air resistance measuring method using the air resistance measuring apparatus A will be described with reference to FIGS.

First, the structure of the air resistance measuring apparatus A of Example 1 will be described.
As shown in FIG. 1, the air resistance measuring device A of Example 1 is installed in an installation recess 1 formed by cutting a traveling road surface RD, and includes a measurement plate 2.

The measurement plate 2 includes a measurement plate main body 20 and caterpillar members 21 and 22.
The measurement plate body 20 is formed in a plate shape with metal or the like, and is supported by the support base (support means) 4 at a height that does not cause a step in the height direction between the installation recess 1 and the traveling road surface RD. Yes. The measurement plate main body 20 is formed to have a length and a width that allow the front wheel FW and the rear wheel RW of the measured vehicle TM to be simultaneously placed in the traveling direction of the measured vehicle TM indicated by the arrow FR. In the case of Example 1, it is formed in a length of about 6 m with reference to twice the wheel base of the test target vehicle including the vehicle to be measured TM.

  The caterpillar members 21 and 22 are formed by connecting a plurality of plates having substantially the same width as the measurement plate main body 20 in a so-called caterpillar shape, and are connected to both ends of the measurement plate main body 20 in the traveling direction. It is supported by large rollers 31 and 32 installed in the installation recess 1.

  A plurality of small rollers 4 a are interposed between the measurement plate body 20 and the support 4. These small rollers 4 a rotate with low friction, and as shown in FIG. 2, a plurality of these small rollers 4 a are arranged in parallel at a predetermined interval in the longitudinal direction (traveling direction) of the support base 4. That is, when the vehicle to be measured TM travels on the measuring plate 2 in the traveling direction indicated by the arrow FR and the tire surface force acts on the measuring plate 2, the measuring plate 2 is applied with the tire surface force acting direction (traveling direction). (Forward and reverse directions) is supported by the support base 4 so as to be movable.

  Further, as the measurement plate main body 20 moves in the traveling direction, the caterpillar members 21 and 22 move along the outer circumferences of the large rollers 31 and 32 while rotating the large rollers 31 and 32, Interference with the edge of the installation recess 1 is prevented.

The large rollers 31 and 32 are supported so as to be rotatable about the rotation shafts 31c and 32c, respectively, and as shown in FIG. 2, a pair of large rollers 31 and 32c is provided on each of the rotation shafts 31c and 32c.
The rotating shafts 31c and 32c extend in the width direction of the measuring plate 2, and can be rotated by brackets 31b and 32b installed upright on the bases 31a and 32a installed on the bottom surface 1a of the installation recess 1. It is supported by.

  Further, as shown in FIG. 1, a plurality of engagement teeth 31 d and 32 d that mesh with the caterpillar members 21 and 22 are formed on the outer periphery of the large rollers 31 and 32. Furthermore, engaging projections 31f and 32f that can be engaged with stoppers 31e and 32e provided on the bases 31a and 32a are formed in the lower part of the large rollers 31 and 32 in the drawing so as to protrude in the outer diameter direction. Therefore, the large rollers 31 and 32 are rotatable in the traveling direction and in the opposite direction within the range of the gap provided between the engaging protrusions 31f and 32f and the stoppers 31e and 32e.

  As shown in FIG. 2, a torque meter (load sensor) 51 is provided on the rotation shaft 31 c of one of the large rollers 31 and 32. The torque meter 51 measures torque when the measurement plate 2 is displaced by the tire outer surface force of the vehicle TM to be measured and the caterpillar members 21 and 22 rotate the large roller 31. That is, the tire surface force acting on the measurement plate 2 is obtained from the measured torque and the rotation radius of the large roller 31 as described later.

  The large roller 31 is given an initial load in a direction opposite to the traveling direction of the arrow FR by a weight (biasing means) 31g shown in FIG. As a result, the friction such as the bearing friction of the small roller 4a and the large rollers 31 and 32 acting on the measurement plate 2 is canceled, and the measurement accuracy of the torque meter 51 is prevented from deteriorating.

  Further, the detected value of the torque meter 51 is input to the processing device (calculation means) 6 shown in FIG. In addition to the torque meter 51, the processing device 6 includes a first infrared sensor 52, a second infrared sensor 53, a time measurement timer 54, an accelerometer 55, an anemometer 56, an anemometer 57, an atmospheric pressure gauge 58, an atmospheric temperature gauge 59. Is connected.

As shown in FIG. 1, the accelerometer 55 and the two infrared sensors 52 and 53 are installed in the measurement plate body 20.
The accelerometer 55 measures the acceleration generated when the tire surface force acts on the measurement plate 2 when the vehicle TM to be measured is riding on the measurement plate 2.

  Both infrared sensors 52 and 53 are for detecting signals transmitted from an infrared transmitter 61 installed at the front of the vehicle TM to be measured, and are installed at both ends of the measuring plate body 20 in the traveling direction. . These infrared sensors 52 and 53 are arranged at a predetermined interval, and based on this interval and the timing of input from the infrared transmitter 61, the speed of the vehicle TM to be measured and the position on the measurement plate 2 Can be calculated.

  The anemometer 56, the anemometer 57, the barometer 58, and the atmospheric temperature meter 59 are assembled together in one measuring unit (ambient environment measuring means) 50, and are around the vehicle TM to be measured on the measuring plate 2. Measure the wind direction, wind speed, atmospheric pressure, and atmospheric temperature, which are environmental impacts.

Next, an outline of a method for measuring the air resistance using the air resistance measuring apparatus A of the first embodiment will be described.
The running resistance value of the vehicle can be expressed by a three-term quadratic equation shown in the following equation (1) depending on the vehicle speed.
(W / g) (1 + f) (dV / dt) = D _T + D _R + Da (1)
Note, W is the weight of the vehicle (Unit: kg), g is gravitational acceleration (m / ^sec 2), V is the vehicle speed (m / sec), _{D T} is the drive shaft losses, _{D R} is the rolling resistance loss, Da is Air resistance loss.

Further, the drive shaft loss D _T , the rolling resistance loss D _R , and the air resistance loss Da can be expressed by the following formulas (2), (3), and (4), respectively.
D _T = W (τ ₀ + bV) (2)
D _R = W (f ₀ + kV ² ) (3)
Da = Cd (1/2 g) × V ² F (4)

In the above equation, τ ₀ is a coefficient of the constant term of the drive shaft loss, b is a coefficient of the speed proportional term of the drive loss, f ₀ is a coefficient of a constant term of the rolling resistance loss, and k is a square of the speed of the rolling resistance loss. The coefficient of the proportional term, F, is the front area (m ² ) of the vehicle.

Therefore, the running resistance of a vehicle traveling on a real road at a constant speed is expressed by the following formula (5): “tire rolling resistance” lost due to tire deformation generated when the tire tread surface is in contact with the road surface, the axle From the "mechanical resistance" that is a set of resistance caused by bearing friction, the resistance that occurs when the disc brake pad and rotor do not act on the brake fluid pressure, and the "air resistance" caused by airflow acting on the vehicle body It is configured.
Driving resistance at constant vehicle speed = tire rolling resistance + mechanical resistance + air resistance (5)
The mechanical resistance of the above formula (5) can be expressed by the following formula (6).
Mechanical resistance = Hub bearing resistance + Brake drag resistance (6)

  Furthermore, considering the tire outer peripheral surface that is in contact with the road surface, the force transmitted by the tire outer peripheral surface to the road surface (this is referred to as the tire surface force) is derived from the force transmitted by the drive shaft to the tire. It is the force obtained by subtracting “resistance” and “mechanical resistance”.

Therefore, the tire surface force can be expressed by the following formula (7).
Tire surface force = Drive shaft force-Tire rolling resistance-Mechanical resistance (7)

  From the above formulas (5) and (7), the tire surface force, which is the force transmitted from the tire outer peripheral surface to the road surface, is equivalent to “air resistance”.

  Therefore, in the air resistance measurement apparatus A of Example 1, paying attention to the fact that the total value of the tire surface force in the traveling direction of the vehicle running at a constant speed on the real road is equivalent to the air resistance on the real road, The tire surface force during travel of the measuring plate 2 of the measuring device A is measured, and the air resistance is calculated from this measured value.

  Next, in the processing device 6 of the air resistance measuring device A of Example 1, the flow of processing for obtaining the tire surface force and the air resistance will be described with reference to the flowcharts of FIGS.

Steps S1 to S8 are processes for accumulating data.
First, in step S1, information on the vehicle to be measured TM is input. This input information is at least the wheel base length of the vehicle TM to be measured and the types of front wheel drive, rear wheel drive, and four wheel drive. These inputs may be performed manually, or tag information given to the vehicle to be measured TM may be read.

  Next, in step S2, it is determined whether or not there is an input to the first infrared sensor 52. If there is an input to the first infrared sensor 52, the process proceeds to step S3. If there is no input, step S2 is performed. repeat. In addition, when there is an input to the first infrared sensor 52, it indicates that the vehicle to be measured TM has reached a position just before entering the measuring plate 2.

In step S3, a start reference time Ts serving as a measurement reference is set, and the start reference time Ts is set to 0 (hereinafter referred to as time ZERO).
In subsequent step S4, the trigger signal for starting data collection is turned ON, and the setting is made to accumulate data from one second before the trigger signal is turned ON. That is, the data from the time point before the vehicle to be measured TM gets into the measurement plate 2 is accumulated.

  In step S5, signal acquisition from the torque meter 51, the two infrared sensors 52 and 53, the time measurement timer 54, the accelerometer 55, the anemometer 56, the anemometer 57, the atmospheric pressure gauge 58, and the atmospheric temperature gauge 59 is started.

  In the next step S6, it is determined whether or not there is an input from the second infrared sensor 53. If there is an input, in the subsequent step S7, a front wheel separation just before time Te is set. The time Te immediately before the front wheel detachment is a time immediately before the front wheel FW descends from the measurement plate main body 20.

  Further, in step S8, the trigger signal for ending data collection is turned ON, and after the trigger signal is turned ON, data is stored until one second later, and then the data storage is ended.

  When the data accumulation is completed, an averaging process is performed in step S9. That is, in step S9, measurement time, average vehicle speed Vm, average atmospheric temperature, average atmospheric pressure, average wind speed, and average wind direction are obtained from the accumulated data.

In subsequent steps S10 to S13, the data to be extracted is sorted.
In step S10, the output change of the accelerometer 55 per unit time is calculated.

In step S11, based on the waveform of the output change value of the accelerometer 55, the phase P1, P2, P3 shown in FIGS. 6 to 8 and the times t1, t2, t3 are obtained.
The first phase P1 is a state in which only the front wheel FW is on the measurement plate 2, the second phase P2 is a state in which the front wheels FW and the rear wheels RW, that is, all wheels are on, and the third phase P3 is a rear wheel. A state where only RW is on board.
Further, t1 is an elapsed time from the time ZERO when the front wheel FW gets into the measurement plate main body 20 and is referred to as a front wheel getting-in time, and t2 is a time when the vehicle front and rear wheels FW and RW get into the measurement plate main body 20. The elapsed time from the time ZERO, which is referred to as the all-wheel boarding time, and t3 is the elapsed time from the time ZERO when the front wheel FW descends from the measuring plate body 20, and is referred to as the front wheel departure time.

In step S12, a calculated all-wheel boarding time T2 is obtained by calculation separately from the all-wheel boarding time t2 obtained by the accelerometer 55. This calculated all-wheel boarding time T2 is calculated from the start reference time Ts (time ZERO) based on the average vehicle speed Vm and the wheel base value of the vehicle TM to be measured. It calculates | requires by Formula (8).
T2 = Wheelbase / Average vehicle speed (8)

  In step S13, the output of the accelerometer 55 and the output of the torque meter 51 from the calculated all-wheel boarding time T2 to the front wheel disengagement time Te are extracted. Note that the time zone between the calculated all-wheel boarding time T2 and the front wheel detaching time Te is a time zone in which all the wheels FW and RW are reliably on the flat measuring plate body 20.

  Next, in step S14, the change per unit time of the output of the torque meter 51 from the all-wheel boarding time T2 to the front wheel disengagement time Te is calculated.

  Further, in step S15, a section in which the output change of the torque meter 51 and the output change of the accelerometer 55 per unit time are below a certain condition and can be determined as a stable state is determined.

In the next step S16, the output of the torque meter 51 in that section is averaged, and further, the tire surface force is calculated by the following equation (9) based on the radius of the large roller 31, and this is set as the air resistance.
Tire surface force = Nm / m (9)
Nm is an average value of the torque meter output, and m is the length (radius) of the arm of the large roller 31.

The next steps S17 to S19 perform weather correction.
That is, in step S17, the wind speed component in the traveling direction is calculated from the wind direction wind speed measurement value. The wind speed acting on the measured vehicle TM is calculated from the wind speed component and the average vehicle speed of the measured vehicle TM, and the air resistance loss Da obtained in step S16 is corrected.

  In step S18, the reference conditions, for example, the atmospheric temperature of 20 ° C. and the atmospheric pressure of 101 kPa are compared with the experimental conditions, and the air density is further corrected for the air resistance.

  In step S19, the resistance coefficient Cd is calculated from the corrected air resistance (= air resistance loss Da) and the known vehicle front area F.

That is, if the air resistance loss Da, the vehicle front surface area F, and the speed V are known in the above equation (4), the resistance coefficient Cd can be obtained.
Thus, the process ends.

Next, a measurement example when a rear wheel drive vehicle is used as the vehicle to be measured TM will be described.
At the time of this measurement, the vehicle to be measured TM is caused to travel at a constant vehicle speed and is passed over the measurement plate 2 in the direction indicated by the arrow FR as shown in FIG.

  At this time, as shown in FIG. 1, when the infrared of the infrared transmitter 61 is detected by the first infrared sensor 52 when the vehicle TM to be measured approaches the measurement plate 2 and the front wheel FW gets into the measurement plate 2. The process after step S2 in the flowchart is started, and the accumulation of data from one second before is started (step S4). Further, when the vehicle to be measured TM reaches the position of the second infrared sensor 53 and is about to get off the front wheel FW from the measuring plate 2, a front wheel disengagement time Te is set and data up to 1 second after that is accumulated. (Step S7).

  The output of the torque meter 51 accumulated in this way is as shown in FIG. Here, in the output waveform of the torque meter 51, the force with which the measurement plate 2 is pushed in the traveling direction (the direction of the arrow FR in FIG. 1) is negative, and the force with which the measuring plate 2 is pushed in the direction opposite to the traveling direction is positive. For the explanation of the operation, the friction of the small roller 4a supporting the measurement plate 2 and the weight of the measurement plate 2 are ignored.

  As shown in this figure, in the first phase P1 in which the front wheel FW, which is a non-driven wheel of the vehicle to be measured TM, has entered the measuring plate 2, the measured value of the torque meter 51 is the rolling of the non-driven wheel as shown in the figure. Negative output for resistance.

  Thereafter, in the second phase P2 in which the rear wheel RW, which is a drive wheel, enters the measurement plate 2 and all the wheels FW and RW are in contact with the measurement plate 2, the output of the torque meter 51 is measured by the total value of the tire surface force. As a result, a positive output is obtained. The tire outer surface force in this state corresponds to air resistance.

  In the third phase P3 in which the front wheel FW descends from the measurement plate 2 and only the rear wheel RW, which is the driving wheel, rides on the measurement plate 2, the output of the torque meter 51 adds the front wheel rolling resistance to the air resistance. Value.

  Thereafter, when the rear wheel RW also descends from the measurement plate 2, the output value of the torque meter 51 becomes “0” as shown. At this time, exactly, the output is obtained by subtracting the mechanical friction of the apparatus from the preload by the weight 31g.

In FIG. 6, each phase P1, P2, P3 is indicated by the output value of the torque meter 51, but each time t1, t2, t3, which is the change timing of each phase P1, P2, P3, is shown in step S11. Based on the above process, it is obtained based on the output of the accelerometer 55.
As described above, the front wheel boarding time t1, the all wheel boarding time t2, and the front wheel leaving time t3 are obtained based on the output of the accelerometer 55, so that the change timing of the torque input state with respect to the measurement plate 2 is detected with high accuracy. ing.

  Further, the tire surface force used to determine the air resistance is the output of the second phase P2 in the case of a rear wheel drive vehicle, and the tire surface force is determined in step S16 based on the output of the torque meter 51 at this time. .

Further, in the first embodiment, as the output of the torque meter 51 in the second phase P2, data between the calculated all-wheel entering time T2 and the front wheel disengagement time Te is used (steps S14 to S16). . Thereby, the output of the torque meter 51 when all the wheels FW and RW are reliably in contact with the flat measuring plate main body 20 is used, and the output in contact with the caterpillar members 21 and 22 is excluded.
In Example 1, since the value obtained by subtracting mechanical friction such as bearing friction from preload is added to the output of the torque meter 51, correction for subtracting the added amount is performed to obtain the tire surface force. I want to ask.

  Further, the air resistance loss Da is calculated based on the obtained tire surface force and the correction value, and the resistance coefficient Cd is calculated.

Next, the case where a front wheel drive vehicle is used as the vehicle to be measured TM will be described.
FIG. 7 shows an output waveform of the torque meter 51 when a front wheel drive vehicle is used as the vehicle to be measured TM.

  In the case of a front-wheel drive vehicle, in the first phase P1 in which only the front wheel FW has entered, the front wheel FW is a drive wheel, so the output of the torque meter 51 is the resistance of the non-drive wheel (rear wheel RW) to the air resistance. The added value.

  On the other hand, in the second phase P2 in which all the wheels FW and RW thereafter have entered the measuring plate 2, the output value of the torque meter 51 is subtracted from the negative value that is the rolling resistance of the rear wheel RW that is a non-driven wheel. This value indicates air resistance.

  In the third phase P3 in which the front wheel FW as the driving wheel descends from the measuring plate 2, the measuring plate 2 is pushed in the traveling direction by the rolling resistance of the rear wheel RW as the non-driving wheel, and the output of the torque meter 51 Is negative.

  Therefore, also in the case of a front wheel drive vehicle, the air resistance is calculated based on the output of the second phase P2.

Next, the case where a four-wheel drive vehicle is used as the vehicle to be measured TM will be described.
In the case of a four-wheel drive vehicle, in the first phase P1 in which only the front wheel FW gets into the measurement plate 2, the output of the torque meter 51 is the force (F1) that the front wheel FW pushes the measurement plate 2 as shown in FIG. Corresponding positive output.

  Thereafter, in the phase P2 in which the tire surface forces of all the wheels FW and RW act on the measurement plate 2, the output of the torque meter 51 becomes a larger value, which corresponds to the air resistance.

  Then, when the front wheel FW descends and the third phase P3 in which only the rear wheel RW rides on the measurement plate 2 is reached, the output of the torque meter 51 is a plus corresponding to the force (F2) that the rear wheel RW pushes the measurement plate 2 Output.

  As described above, in Example 1, the tire surface force in a state where the vehicle is traveling at a constant speed is obtained, and the air resistance is obtained from the tire surface force. In comparison, it is possible to obtain an air resistance with higher accuracy by eliminating an error from the air resistance during actual traveling.

  Moreover, in Example 1, each time t1, t2, t3 which is a change timing of each phase P1, P2, P3 from which the contact state of each wheel FW, RW with respect to the measurement board 2 differs is based on the output of the accelerometer 55. I want to ask. Since the output of the accelerometer 55 immediately responds to changes in the force with which the wheels FW and RW press the measuring plate 2, the time t 1, t 2 and t 3 are compared with those obtained based on the output of the torque meter 51. Thus, it can be obtained with high responsiveness and high accuracy.

  Further, in the first embodiment, as data of the second phase P2 for calculating the tire surface force, data of a time zone from the calculated all-wheel boarding time T2 to the front wheel disengagement time Te is used. This is data of the torque meter 51 when all the wheels FW and RW are in contact with the flat measuring plate body 20, and excludes data when the rear wheel RW is in contact with the caterpillar members 21 and 22. By doing so, more accurate tire surface force can be obtained. Therefore, compared with the case where the data which contacted the caterpillar member 21 and 22 is included, the error with actual air resistance can be eliminated more.

  In addition, in the first embodiment, in step S15, data of a section in which it can be determined that the outputs of the torque meter 51 and the accelerometer 55 are stable is used. Therefore, as compared with the case where this determination is not performed, it is possible to eliminate the influence of disturbance (for example, the influence of dust, pebbles, water, etc. on the measurement plate 2) and obtain the air resistance with higher accuracy.

  Furthermore, in the first embodiment, the measuring plate 2 is arranged at substantially the same height as the surrounding traveling road surface RD, and is arranged so as not to cause a step between the two, so that the vehicle to be measured TM is implemented at a constant speed. When traveling on the measurement plate 2 of the example apparatus A, it is possible to travel stably and obtain stable data as compared with the case where there is a step. Thereby, generation | occurrence | production of an error can be suppressed.

  Further, in the first embodiment, the measuring plate 2 is constituted by the flat measuring plate main body 20 and the caterpillar members 21 and 22 at both ends thereof, and the caterpillar members 21 and 22 are wound up by the large rollers 31 and 32. The measurement plate 2 was prevented from interfering with the opening edge of the installation recess 1. Therefore, it is possible to prevent the outputs of the torque meter 51 and the accelerometer 55 from being affected by such interference and reaction force, thereby improving accuracy and improving durability of the apparatus. it can.

  In addition, a weight 31g is provided on the large roller 31 to apply an initial load in a direction opposite to the traveling direction, thereby canceling friction such as bearing friction of the small roller 4a and the large rollers 31 and 32. For this reason, the detection accuracy of the tire surface force by the torque meter 51 can be improved as compared with the case where the initial load by the weight 31g is not applied.

  As mentioned above, although Embodiment and Example 1 of this invention were explained in full detail with reference to drawings, the concrete structure is not restricted to this Embodiment and Example 1, and does not deviate from the summary of this invention. A degree of design change is included in the present invention.

  That is, in Example 1, although the example which formed the measurement board 2 with the flat measurement board main body 20 and the caterpillar members 21 and 22 was shown, it is not limited to this, For example, the flat measurement board 200 shown in FIG. You may comprise only. The measuring plate 200 is slidably supported on the traveling road surface RD via the slide support means 204. Further, it is assumed that the slide support means 204 is provided with a stopper that restricts further sliding when the measuring plate 200 is slid by a predetermined amount and a torque sensor that detects a load acting in the sliding direction.

  Further, in the first embodiment, the example in which the change timing of each phase P1, P2, P3 is obtained from the output of the accelerometer 55 is shown, but this may be detected from the output of the torque meter 51. Alternatively, since the tire surface force may be calculated only by knowing the output of the torque meter 51 in the second phase P2, the accelerometer 55 is eliminated, and the second phase P2 is obtained only by the calculation in steps S14 to S16. May be.

  Further, the urging means for applying the initial load in the moving direction to the measuring plate 2 in the present invention is not limited to the weight 31g shown in the first embodiment. In short, the biasing means only needs to be able to cancel the friction acting on the measurement plate in the forward and reverse direction of the traveling direction, and other means such as a spring can be used in addition to the weight 31g. The installation position may also be another position such as inputting an urging force directly to the measurement plate 2.

  Moreover, in Example 1, the 1st infrared sensor 52 which detects the infrared rays transmitted from the infrared transmitter 61 provided in the to-be-measured vehicle TM was shown as boarding detection means, However, It is not limited to this. For example, other means such as a means for detecting getting in contact with the tire may be used.

It is a general view which shows the structure of the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is a top view which shows the principal part of the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is a block diagram which shows the processing apparatus 6 corresponded to the calculating means of the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is a flowchart which shows the flow of a process of the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is a flowchart which shows the flow of a process of the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is a time chart which shows the output example of the torque meter 51 at the time of the measurement of a rear-wheel drive vehicle in the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is a time chart which shows the output example of the torque meter 51 at the time of the measurement of the front-wheel drive vehicle in the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is a time chart which shows the output example of the torque meter 51 at the time of the measurement of a four-wheel drive vehicle in the air resistance measuring apparatus A of Example 1 of embodiment of this invention. It is the schematic which shows the structure of the other example of embodiment of this invention.

Explanation of symbols

2 Measuring plate 4 Support stand (support means)
6. Processing device (calculation means)
31g Weight (biasing means)
50 Measuring unit (Ambient environment measuring means))
51 Torque meter (load sensor)
52 1st infrared sensor (boarding detection means)
55 Accelerometer (Acceleration sensor)
FW Front wheel RW Rear wheel RD Road surface TM Vehicle to be measured

Claims (9)

Measure the tire surface force, which is the force transmitted by the tire outer peripheral surface to the road surface of the vehicle to be measured traveling at a constant speed,
An air resistance measuring method, wherein the air resistance of a vehicle to be measured is obtained from the measured tire surface force.   The air resistance measurement method according to claim 1, wherein the tire surface force is obtained from a sum of tire surface forces of all wheels. A measurement plate that is continuously arranged on the traveling road surface and has a length in the traveling direction in which all wheels of the vehicle to be measured can simultaneously contact and a width in the orthogonal direction;
A measuring means for measuring a tire surface force, which is a force transmitted from the outer peripheral surface of the tire to the measuring plate when the vehicle travels on the measuring plate;
An air resistance measuring device comprising: The measurement plate is supported by the support means so as to be movable in the forward and reverse directions of the traveling direction,
The measurement means includes a load sensor that measures a load acting in the forward and reverse directions of the traveling direction with respect to the measurement plate, and a calculation means that obtains the tire surface force based on an output of the load sensor. The air resistance measuring device according to claim 3.   2. The tire surface force is obtained based on an output of a load sensor when all the wheels are simultaneously on the measurement plate when the vehicle to be measured travels on the measurement plate. 4. The air resistance measuring device according to 4.   The air resistance measuring device according to any one of claims 3 to 5, further comprising an urging unit that applies an initial load to the measurement plate in a moving direction thereof. An acceleration sensor that detects acceleration acting in the forward and reverse directions of the traveling direction with respect to the measurement plate is provided;
The air resistance according to any one of claims 4 to 6, wherein the calculation means determines a measurement plate contact state of a wheel of the vehicle to be measured based on an output of the acceleration sensor. measuring device. The measurement board is provided with boarding detection means for detecting boarding of the vehicle to be measured,
The calculation means obtains the time during which all the wheels are in contact with the measurement plate from the boarding timing of the vehicle to be measured detected by the boarding detection means and the wheelbase length of the vehicle to be measured input in advance. The air resistance measuring device according to any one of claims 5 to 7, wherein a tire surface force is obtained based on an output of the load sensor within this time. Surrounding environment measuring means for measuring at least one of wind speed, wind direction, atmospheric pressure, and atmospheric temperature when the vehicle to be measured is running on a measurement board,
The air according to any one of claims 3 to 8, wherein the calculation means corrects an air resistance obtained from a tire surface force based on a measurement value of the surrounding environment measurement means. Resistance measuring device.

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