JP2016080636A - Vehicle loss measurement device and vehicle loss measurement method in chassis dynamometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle loss measurement device in a chassis dynamometer capable of measuring vehicle loss in consideration of acceleration and deceleration during exhaust gas fuel cost test mode operation.SOLUTION: A vehicle loss measurement device in a chassis dynamometer that performs various tests of a test vehicle 1 installed on a roller 2 includes a controller 10 that makes the chassis dynamometer a speed control mode and performs operation control with the vehicle speed pattern of an exhaust gas fuel cost test mode, and an operation unit 20 for subtracting loss of a single chassis dynamometer from mechanical loss detected by the load cell of the chassis dynamometer during operation in the exhaust gas fuel cost test mode to obtain the vehicle loss.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle loss measuring apparatus and method for measuring vehicle loss such as rolling resistance of a vehicle using a chassis dynamometer.

  The chassis dynamometer gives a running resistance equivalent to that of a vehicle running on the road as much as possible to a vehicle under test mounted on a roller, and performs various tests such as fuel consumption and exhaust gas.

  That is, for example, in a four-wheel drive vehicle (4WD), in order to output a driving force against a traveling load (inertia resistance, rolling resistance, air resistance) to the vehicle engine, the target driving force of the front and rear wheels in total on the roller is Torque control of the two chassis dynamometers is performed so as to be obtained.

  Conventionally, mechanical loss (vehicle loss) such as rolling resistance of a vehicle is measured at the chassis dynamometer load cell by measuring the coasting time on the chassis dynamometer or by driving at a constant speed from the chassis dynamometer. It was something to do. For this reason, it was a loss measurement in the steady state at each measurement vehicle speed.

  Patent Document 1 describes that the measurement result is verified by matching the mechanical loss measurement result by the coasting method and the motoring method. Non-Patent Document 1 describes a technique used during measurement of vehicle internal resistance among the verification experiments in the embodiment of the present invention. Non-Patent Document 2 describes the verification experiment in the embodiment of the present invention. Among them, an advanced tire testing machine for reproducing changes in load and rotation of front and rear wheels is described.

JP 2008-224403 A

Noda et al., Automobile Engineering Society Proceedings Vol. 44 no. 3 p. 823 20134460 Inoue et al., Automotive Engineering Society 2010 Spring Meeting Pre-print 20105239

  Conventional measurement of mechanical loss is measurement in a steady state at each vehicle speed, and measurement in the case of driving including acceleration / deceleration in an actual exhaust gas fuel consumption test mode has not been performed.

  For this reason, loss such as tire deformation caused in the case of driving including acceleration / deceleration is not taken into account, and vehicle loss measurement in a state close to the actual cannot be performed.

  The present invention solves the above-described problems, and an object thereof is to provide a vehicle loss measuring device and method in a chassis dynamometer capable of measuring vehicle loss in consideration of acceleration / deceleration during exhaust gas fuel consumption test mode operation. It is in.

  The vehicle loss measuring device in a chassis dynamometer according to claim 1 for solving the above-mentioned problem is a vehicle loss measuring device in a chassis dynamometer for performing various tests of a vehicle under test mounted on a roller. The chassis dynamometer alone, based on the control means that controls the dynamometer in the vehicle speed pattern in the exhaust gas fuel consumption test mode and the mechanical loss detected by the load cell of the chassis dynamometer during operation in the exhaust gas fuel consumption test mode. And calculating means for subtracting the loss to obtain the vehicle loss.

  The vehicle loss measuring device for a chassis dynamometer according to claim 2 is characterized in that the speed control in the exhaust gas fuel consumption test mode is executed by an automatic speed maintenance control function of the chassis dynamometer.

  A vehicle loss measurement method for a chassis dynamometer according to claim 3 is a vehicle loss measurement method for a chassis dynamometer that performs various tests on a vehicle under test mounted on a roller, and the control means includes the chassis dynamometer. The operation control step for controlling the operation with the vehicle speed pattern in the exhaust gas fuel consumption test mode with the meter in the speed control mode, and the calculation means from the mechanical loss detected by the load cell of the chassis dynamometer during operation in the exhaust gas fuel consumption test mode, And a calculation step of subtracting the loss of the chassis dynamometer alone to obtain the vehicle loss.

  According to a fourth aspect of the present invention, there is provided a vehicle loss measuring method for a chassis dynamometer, wherein the control means sets the transmission of the vehicle under test to neutral before the execution of the operation control step. The vehicle includes a step of warming up the vehicle.

  Further, the vehicle loss measuring method in the chassis dynamometer according to claim 5 is characterized in that the operation control step is executed by an automatic speed maintenance control function of the chassis dynamometer.

  According to the above configuration, the vehicle loss is taken into account in consideration of tire deformation and the like during acceleration / deceleration operation in the exhaust gas fuel consumption test mode.

  According to the present invention, it is possible to measure the vehicle loss taking into account the acceleration and deceleration during the exhaust gas fuel consumption test mode operation, and it is possible to measure the vehicle loss that is closer to the actual state than in the past.

The block diagram of the vehicle loss measuring apparatus by the example of embodiment of this invention. The flowchart which shows an example of the vehicle loss measurement method by the example of embodiment of this invention. The graph of the vehicle speed pattern of JC08 mode used by the driving control of the example of embodiment of this invention. The conceptual diagram of the energy balance at the time of mode driving | running | working on a chassis dynamometer in the verification experiment of this invention. In the verification experiment of this invention, the measurement result of the vehicle resistance force at each speed is shown, (a) is a graph when the vehicle is naturally coasting on the table, (b) is an automatic speed maintenance control (b) of the chassis dynamometer ( A graph when the vehicle is driven at a constant speed by ASR). The graph showing the rolling resistance of the front and rear wheel tires for each speed when the vehicle tire is rotated at a constant speed by ASR control in each drive mode in the verification experiment of the present invention. In the verification experiment of the present invention, the loss rate due to each rolling resistance of the front and rear wheel system when traveling in each drive mode is represented, (a) is a graph when the speed change of JC08 mode is given, (b) is 40 Km / h Graph for constant speed conditions. The graph showing the vehicle internal work loss calculated | required by each method of the JC08 mode driving | running | working method by ASR control, the table coasting method, the ASR constant speed drive method, and the method of calculating from a target driving resistance value in the verification experiment of this invention. The graph showing the ratio of the work amount resulting from the work amount on the chassis dynamometer side and the vehicle internal resistance in each drive mode of the vehicle in the verification experiment of the present invention. The graph of the tire loss amount for each driving condition of the vehicle in the verification experiment of the present invention. The graph showing the measured value of JC08 mode fuel consumption for every condition of each drive condition and each chassis dynamometer in the verification experiment of this invention. The graph showing the relationship between a fuel consumption rate and the vehicle side work rate in the verification experiment of this invention. The graph showing the relationship between the rear wheel side roller surface force and a tire radius in the verification experiment of this invention. The graph showing the frequency distribution of tire temperature in the verification experiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. FIG. 1 shows the overall configuration of an embodiment of a vehicle loss measuring device in a chassis dynamometer of the present invention.

  In FIG. 1, reference numeral 1 denotes a vehicle under test. Each drive wheel of the vehicle under test 1 is placed on a roller 2, and the vehicle itself is fixed by a restraining device (not shown). Two unillustrated dynamometers for front wheels and rear wheels are coupled to the roller 2 as loads.

  3 is a vehicle cooling fan that blows wind force from the front side of the vehicle 1 under test, 4 is a tire cooling fan that blows wind force to the contact surface between each tire of the four wheels and the roller 2, and 5 is a floor surface.

  Although not shown, a non-contact thermometer for measuring the tire temperature and a hot-wire anemometer for measuring the tire peripheral wind speed are attached to the vehicle body or the like.

  A control device (control means) 10 includes a dynamometer control device for controlling the two dynamometers, a control device for the vehicle cooling fan 3, a control device for the tire cooling fan 4, and the like.

  The control device 10 sets the dynamometer in a speed control mode, and performs operation control in an exhaust gas fuel consumption test mode, for example, a vehicle speed pattern in the JC08 mode shown in FIG.

  The speed control in the JC08 mode is executed by the automatic speed maintenance control function (ASR control) of the chassis dynamometer.

  Further, the control device 10 has a function of performing torque control of the two dynamometers so that the target driving force of the front and rear wheels can be obtained on the roller 2.

  Further, since the roller 2 plays the role of the road surface during actual traveling, the control device 10 performs synchronous control of the two dynamometers so that the rotational speeds of the front and rear rollers always coincide with each other under any operating condition. It has a function.

  Further, in order to achieve the two functions at the same time, the control device 10 automatically adjusts the torque absorption distribution amount of the front and rear dynamometers and achieves rotation synchronization while adjusting the front and rear total driving force to the target value.

  Reference numeral 20 denotes a chassis dynamometer that is measured in advance from a mechanical loss (mechanical loss) detected by a load cell of the chassis dynamometer during operation in the exhaust gas fuel consumption test mode (for example, JC08 mode) and stored in the storage means. It is a calculation part (calculation means) which calculates | requires a vehicle loss by subtracting the single loss 21. FIG.

  The speed pattern of the JC08 mode in FIG. 3 is a mode that changes to the conventional 10.15 mode, and the engine is operated not only in a warm speed but also in a cold state in order to approach the actual usage situation. The maximum speed is 81.6 Km / h, the average speed is 24.4 Km / h, the required time is 1204 seconds, and the travel distance is 8.172 Km.

  In constructing the present invention, the present inventors conducted the following verification experiments (1) to (12), and reflected the experimental results in the present invention.

  In the verification experiment, using a 4WD vehicle that can select 2WD or 4WD, JC08 mode tabletop driving is performed under 2WD conditions and 4WD conditions, and the engine load and total engine work of both are analyzed. did. In addition, we investigated the factors causing the difference in total workload, and also considered the relationship between the workload difference and fuel consumption.

  The experiment was conducted by selecting the following three methods as the drive mode of the 4WD vehicle. When the 2WD mode is set, the front wheel side is in a free state, and driving is performed by rear wheel drive (hereinafter referred to as 2WDr).

  In the case of the 4WD mode, the following two modes can be selected. One is a full-time 4WD mode (hereinafter referred to as 4WDft) with a center differential, and a viscous differential limiting mechanism (LSD) is interposed.

  The other 4WD system is a part-time type 4WD (hereinafter referred to as 4WDpt) that locks the center differential and directly connects the front and rear, and is not suitable for cornering driving due to its structure, but on a 4WD compatible chassis dynamometer with no difference between left and right There is no problem in driving.

  The size of the blowout port of the vehicle cooling fan that affects the tire temperature is 1300 × 700 mm, and the vehicle speed following wind speed control up to 140 Km / h is enabled.

  The test vehicle was fixed in a chain restraint system with a total of four points in the front and rear in all modes of 2WDr, 4WDft, and 4WDpt. For the purpose of investigating the influence of the vehicle's platform swing, we also experimented with a method of winding a belt around the front wheel and fixing it in the 2WDr mode. Further, as 2WDr running close to actual running, the front wheel is rotated in synchronization with the rear wheel, and the resistance force is superimposed on the rear wheel absorption force, that is, the total when the chassis dynamometer is set to the 4WD mode and the vehicle is driven with four wheel rotation. I also checked the workload.

  (1) The total amount of engine work when the test vehicle travels on the chassis dynamometer in the JC08 mode under the conditions of 2WD and 4WD was determined by the following method.

  The total work amount is obtained as an integrated value of the mode travel section of the product (work rate) of the total travel resistance and speed. The engine load when running on the chassis dynamometer includes the power transmission loss, tire resistance and rotation system inertial resistance generated inside the vehicle, and the load applied from the chassis dynamometer on the roller surface (inertia resistance and target running resistance based on the equivalent inertia amount). The difference between the actual rolling resistance of the vehicle).

  Therefore, the breakdown of running work was calculated by measuring the vehicle side resistance and the absorption resistance of the chassis dynamometer separately. FIG. 4 conceptually shows the energy balance during mode running on the chassis dynamometer.

  In FIG. 4, Wvm is the engine load, Wpt is the power transmission loss, Wtf is the front wheel tire resistance, Wtr is the rear wheel tire resistance, Wchf is the absorption resistance force of the front wheel side chassis dynamometer, and Wchr is the absorption force of the rear wheel side chassis dynamometer. It is resistance.

(2) Calculation of travel work by resistance force inside vehicle The vehicle side resistance force and the travel work amount were obtained by the following method. In the experiment, after fixing the test vehicle on the chassis dynamometer, under the driving conditions of 2WDr, 4WDft, and 4WDpt, the automatic speed maintenance control (ASR) of the chassis dynamometer was used from the roller side. The tire was rotated at a constant speed of 20, 40, 60, 80, and 100 km / h, and the surface force of the front and rear rollers at that time was measured. This value corresponds to the vehicle resistance force composed of the vehicle side power transmission loss and the tire loss at each speed.

  For comparison, an experiment was also conducted to determine the running resistance in each vehicle speed range from the deceleration time when the vehicle was allowed to naturally coast on the table.

  FIG. 5 shows the measurement results of the vehicle resistance force at each speed, (a) is a graph when the vehicle is naturally coasting on the table, and (b) is an automatic speed maintenance control (hereinafter referred to as ASR) of the chassis dynamometer. Is a graph when the vehicle is operated at a constant speed.

  The coasting method of FIG. 5 (a) has a slightly larger resistance value, but the cause is presumed to be the effect of different tire temperature conditions in both test methods due to differences in vehicle warm-up and running speed range.

  (3) On the other hand, when a speed change is given from the chassis dynamometer by ASR control, the rotational inertia force after the transmission acts on the test vehicle in addition to the rolling resistance. Under this condition, the same speed change as in the JC08 mode was given to the test vehicle, and the amount of loss caused by the vehicle internal resistance during the mode running was calculated by a method of integrating the product of the roller surface force and the vehicle speed at each moment.

  It is said that the contribution of tire loss is high in rolling resistance. The rubber member around the tire ground contact portion is repeatedly deformed by the rotation and generates heat due to the properties of the viscoelastic body, resulting in tire loss. In addition, ground friction resistance and rotating air friction resistance are added, but deformation loss is about 90% in tire resistance. Since the tire rolling resistance coefficient (RRC) varies with temperature, the tire sidewall temperature during running was also continuously measured in order to see the effect of tire cooling air.

  In the vehicle internal resistance measurement method shown in (2) above, tire loss and power transmission loss cannot be separated. Therefore, based on the method shown in Non-Patent Document 1, changes in the load and rotation of the front and rear wheels when running in JC08 mode under the driving conditions of 4WDft, 4WDpt, and 2WDr are reproduced by the advanced tire testing machine of Non-Patent Document 2. Then, by calculating the torque difference between the tire input / output shafts at that time, the work amount corresponding to the single tire deformation loss at the time of running in the JC08 mode was obtained.

  The acceleration resistance and the target travel resistance (including air resistance) during the mode travel are given to the test vehicle as a chassis dynamometer load. Therefore, the amount of work absorbed by the chassis dynamometer was measured over the entire mode. After setting the equivalent inertial mass and target running resistance in the chassis dynamometer, the JC08 mode is run under the driving conditions of 4WDft, 4WDpt, and 2WDr as the driving mode, and the roller peripheral force is applied to the front and rear roller surface forces (positive value only). The instantaneous work rate was calculated over time, and the total work amount of the mode absorbed by the chassis dynamometer was obtained by integrating over the entire mode section.

  (4) FIG. 6 shows the rolling resistance of the front and rear wheels determined from the value of the roller surface force by rotating at a constant speed by ASR control in each of the 4WDft, 4WDpt, and 2WDr drive modes. In the 2WDr drive mode, the front and rear wheels were measured separately. In the results shown in the figure, the resistance of the rear wheel system is larger than that of the front wheels, and in 4WD, the front wheel resistance in the 4WDft mode in which the differential and viscous mechanisms are interposed is slightly larger than that of 4WDpt in which the front and rear wheels are directly connected. Furthermore, 2WDr with no coupling between the front and rear resulted in the smallest total resistance before and after.

  (5) Next, the loss rate (kJ / km) due to each rolling resistance of the front and rear wheel system when traveling in the JC08 mode in each drive mode was determined. This measurement was performed by an experiment in which a speed change in the JC08 mode was applied to the roller on which the test vehicle was mounted by ASR driving. In this case, the work amount includes the loss of rotational inertia on the vehicle side.

  FIG. 7 shows the measurement results of the loss rate in the JC08 mode and the 40 Km / h constant speed condition. FIG. 7 shows the loss rate due to each rolling resistance of the front and rear wheel system when traveling in each driving mode, (a) is a graph when the speed change of JC08 mode is given, (b) is a constant speed of 40 km / h. It is a graph in the case of conditions.

  In the 2WDr mode bench test, only the rear wheel system was shown because the front wheels did not rotate. Looking at the front-to-back ratio in 4WD traveling, the front wheel side is increased in the JC08 mode as compared to when traveling at a constant speed of 40 km / h. With the difference in driving method, the loss rate of the 4WDft mode was slightly higher than that of the direct connection type 4WDpt mode. The loss rate per distance attributed to such rolling resistance is smaller in JC08 mode traveling than at 40 Km / h constant speed. The negative inertia force applied from the chassis dynamometer during deceleration is the amount of rolling resistance on the vehicle side. Is the result of canceling.

(6) Breakdown of vehicle-side lost work during JC08 mode travel Next, the work when the test vehicle is driven in each of the 4WDft, 4WDpt, and 2WDr drive modes is calculated from the work related to vehicle internal loss and the chassis dynamometer. It was calculated by dividing it into the workload by the given load. The amount of work absorbed by the chassis dynamometer during four-wheel drive running was determined from the sum of the roller surface forces on the front and rear sides.

  In addition, from the viewpoint of simulating 2WD road running, test conditions were also given in which the test vehicle was set to the 2WDr mode and the chassis dynamometer was set to the 4WD mode. In this case, the rolling resistance and the rotational inertia resistance of the front wheel system work, but the rotational force that causes the front wheel roller to follow the rotational speed of the rear wheel is added to the rear wheel roller load.

  This is in common with the principle of actual road running. Furthermore, in the 2WDr test, the method of restraining the vehicle by fixing the front belt was also compared. The purpose of this is to check whether the test vehicle swing and tire deformation change due to the difference in the vehicle fixing method, resulting in a difference in the work load.

  First, the internal work loss of the vehicle during JC08 mode driving is obtained from the roller surface force by applying the speed change of the same mode by ASR control, and the resistance in each vehicle speed range is obtained by the table coasting method and ASR constant speed driving method. The method of calculating the total amount of JC08 mode using the value was compared with the method of calculating from the target running resistance value. The result is shown in FIG.

  In FIG. 8, the black bar graph is based on the JC08 mode running method by ASR control, the wide diagonal line bar graph is based on the table coasting method, the narrow diagonal bar graph is based on the ASR constant speed driving method, and the white bar graph is Each calculated from the target running resistance value is shown.

  At the time of 4WD (4WDft, 4WDpt), the value of the JC08 mode driving method (black bar graph in the figure) by ASR control is slightly large, and it seems that the change in the speed of the roller affected the tire.

  (7) FIG. 9 shows the calculation results of the work on the chassis dynamometer (CHDY) side and the work caused by the vehicle internal resistance in each drive mode. The vehicle side was obtained by a method in which the chassis dynamometer side is ASR controlled and the speed change in the JC08 mode is applied to the test vehicle. As can be seen from the figure, the absorbed work (blacked area) on the chassis dynamometer side is more than half in any vehicle condition, which is due to the large influence of inertial resistance during acceleration. When traveling in the JC08 mode, which is a transient condition, at 4WD, a difference in rotational speed is likely to occur between the front and rear wheels due to factors such as changes in driving force and vehicle body posture, but the effect is not captured by this experimental method.

  On the other hand, in the tests of (3) and (5) of 2WDr, the load of the chassis dynamometer is verified because the verification including the resistance of the front wheel when driving on the road is made and the adjustment is made by the absorption load amount of the rear chassis dynamometer. The amount (black part) increased, and the loss on the vehicle side (outlined part) decreased by the amount of the non-rotating front wheel.

  From the results shown in FIG. 9, the total work amount ((3), (4)) when traveling with two-wheel rotation is 4WDft mode (1), 4WDpt (2) and 2WDr modes with four-wheel rotation. The amount of work was slightly less than that when the chassis dynamometer was in the 4WD mode (4). In other words, even if the target running resistance with the chassis dynamometer was set to a road running value of 4WD, the total work amount was slightly reduced in the two-wheel rotation test. In the two-wheel rotation test, it is possible that the rotational inertia amount of the vehicle is almost halved, and that the actual loss of the tire during table-top traveling may be different between two-wheel traveling and four-wheel traveling.

  (8) Next, 4WDft, 4WDpt, 2WDr are utilized by using the transient test function of the advanced tire testing machine (Non-Patent Documents 1 and 2) in order to grasp the relationship between the driving conditions of the 4WD vehicle and the tire loss during mode driving. Under these conditions, the load and rotation conditions equivalent to those when the JC08 mode was run on a table were given to the tire alone, and the amount of loss per tire for the front and rear wheels was measured for each driving condition. Based on the results, the total tire loss of the vehicle drive wheels was calculated.

  FIG. 10 shows the results of the tire experiment. The vehicle-side power loss (outlined portion) is a value obtained by subtracting the current tire loss (blackened portion) from the total vehicle loss obtained by the above-described method. With respect to the total vehicle loss during running in JC08 mode, the contribution of the tire (diamond mark in the figure) was about 60% for the test tire of this time under any driving condition. Since it is an eco-grade C tire and a 4WD vehicle with a differential mechanism, it seems to be a reasonable number. In addition, since the analysis results of the total loss obtained by the chassis dynamometer vehicle test and the tire unit test that were conducted completely independently were numbers that seemed to be appropriate for both, the tire unit mode test is considered to be a practical method .

(9) Relationship between test vehicle and chassis dynamometer test conditions and fuel consumption It was found that the mode travel work including the internal loss of the vehicle varies depending on the driving conditions of the 4WD vehicle and the usage conditions of the chassis dynamometer. Therefore, how these differences affect the mode fuel efficiency was confirmed by JC08 mode fuel efficiency measurement.

  FIG. 11 shows JC08 mode fuel efficiency values measured three times under each driving condition and chassis dynamometer condition. In the figure, (1) and (2) are 4WD driving, and (3) to (5) are 2WD driving, among which (3) and (4) rotate all four wheels, and (5) only the rear wheels It is rotating. In (3) and (4), 4 wheels are rotating by 2WD drive. (3) is the case of rear wheel drive, the front wheel is controlled to follow the rear wheel by ASR, and (4) is the front wheel. This is a case where control is performed to synchronize the rear wheel. In JC08 mode traveling, there is a possibility that the constant speed rotation of the front and rear wheels may be disrupted during a sudden speed change or during a gear shift or vehicle swing. It is considered that 4WDft absorbs the speed difference by the center differential and the viscous LSD, and 4WDpt absorbs and suppresses deformation of the rubber members near the front and rear tire contact portions.

  In the fuel consumption comparison of 4WDft (1) and 4WDpt (2) in the figure, (1) with a differential absorption mechanism in between was better. In 4WDpt of (2) in which the front and rear are directly connected, the influence of the rotation difference is directed to the tire, and as a result, the tire loss is increased, leading to deterioration in fuel consumption. On the other hand, in (1), since the rotation difference can be absorbed without difficulty by the action of the center differential and the viscous, it is considered that the loss is relatively small. There was almost no difference in fuel consumption between 4WDft (1) and 2WDr (3). Because the test vehicle is fixed in a chain restraint method in which both are tensioned back and forth, the rocking state on the roller of the test vehicle is close to the actual road running, and there is a difference in the mode total work amount in FIG. The small amount seems to be the cause of the small difference in fuel consumption. In the test of fixing the front wheels by winding the belt in (5), the fuel consumption was slightly reduced from (3) of the same 2WDr. Under this condition, since the vehicle body is not restrained by the front and rear chains, the vertical movement on the rear wheel side that is the driving wheel during acceleration / deceleration is larger than that in (3), and the tire deformation during mode driving is accordingly accompanied. Judge that the increase in loss may be the cause.

  Among the experimental conditions, the fuel consumption was the worst under the condition of (4) 2WD driving and 4 wheel rotations on the table. The reason is that the mode total work shown in FIG. 9 is the largest, and there is a difference between the rolling resistance equivalent to the front wheel side when the load is set and the actual rolling resistance on the front wheel side during the transient running of JC08. This is presumably because the absorption capacity of the rear wheel roller of the dynamometer has increased. Further, since the wind of the vehicle cooling fan directly hits the tire on the front wheel side, the tire temperature is likely to fall as described later, and this seems to have caused the actual rolling resistance of the front wheel to increase.

  (10) Next, the relationship between the fuel consumption rate (mL / km) under various test conditions and the vehicle-side work rate (KJ / km) obtained previously was examined. The results are shown in FIG. There is a correlation between the two, but there are also variations. Since the calculation of the work rate so far does not reflect the change in the work amount due to the dynamic change in the tire behavior on the chassis dynamometer, it can be a factor causing the variation in FIG. Therefore, other factors affecting the tire characteristics when traveling on a table were also investigated.

(11) Effect of tire actual operating conditions on total mode work load The tire deformation during actual operation in which the vehicle driving force is transmitted to the roller surface and the influence on the driving loss due to this were considered. As part of the experiment, an experiment was performed in which gradient conditions were added from a chassis dynamometer during constant speed running at 2WD and 4WD, and the relationship between the surface force of the rear wheel roller and the tire radius was determined. The tire radius was obtained from the detected values of the roller peripheral speed and the tire shaft rotational speed, and slip was not included in the calculation. As shown in FIG. 13, the tire diameter (vertical axis) tended to decrease almost linearly as the roller surface force (horizontal axis) increased. It is conceivable that the amount of tire deformation (collapse) increases as the driving force increases, resulting in an increase in tire loss. Since this influence is not included in the calculation of the power of FIG. 12, it can be said that it is a potential fluctuation factor.

  (12) Next, attention was paid to the fact that the RRC (rolling resistance coefficient) changes depending on the tire temperature. The tire side wall temperatures of the front and rear wheels during mode running were continuously measured with an infrared non-contact thermometer to determine the tire temperature frequency distribution. The results are shown in FIG. In FIG. 14, the horizontal axis is the tire sidewall temperature, and the vertical axis is the frequency distribution. The rear wheel tire temperature is 2WDr higher than 4WDft on average, and the effect of the difference in rear wheel brake heat is considered. On the other hand, the temperature of the front wheel tire during four-wheel drive clearly decreased from the rear wheel side. The wind of the vehicle cooling fan directly hits the front wheel side, while the rear wheel side is blocked by the vehicle body to suppress the cooling air speed around the tire, and the wind warmed by the heat of the engine and exhaust pipe from under the floor The cause seems to have been the heat transferred to the tire by going around the rear wheel. In that sense, it is necessary to consider a tire cooling device that can approach the state of the wind hitting the front and rear tires when traveling on a real road.

  Next, an example of a process for measuring vehicle loss using the vehicle loss measurement device of FIG. 1 will be described with reference to the flowchart of FIG.

<Step S1>
The chassis dynamometer and the vehicle under test 1 are warmed up while the vehicle under test 1 is on. As a result, the tire temperature and the like are sufficiently warmed up and the rolling resistance and the like are stabilized (the transmission of the vehicle 1 is neutral).

<Step S2>
The chassis dynamometer is used as a speed control mode, and the vehicle is operated in a vehicle speed pattern in an exhaust gas fuel consumption test mode (for example, JC08 mode in FIG. 3).

<Step S3>
During the above operation, the value detected by the load cell of the chassis dynamometer is measured.

<Step S4>
The vehicle loss is obtained by subtracting the previously measured loss value of the chassis dynamometer alone from the value measured above.

DESCRIPTION OF SYMBOLS 1 ... Test vehicle 2 ... Roller 3 ... Vehicle cooling fan 4 ... Tire cooling fan 10 ... Control apparatus 20 ... Calculation part

Claims (5)

A vehicle loss measuring device in a chassis dynamometer that performs various tests of a vehicle under test mounted on a roller,
The chassis dynamometer is set to a speed control mode, and control means for controlling operation with a vehicle speed pattern in an exhaust gas fuel consumption test mode;
Calculation means for subtracting the loss of the chassis dynamometer alone from the mechanical loss detected by the load cell of the chassis dynamometer during operation in the exhaust gas fuel consumption test mode, and obtaining vehicle loss;
A vehicle loss measuring device in a chassis dynamometer, comprising:   The vehicle loss measuring device for a chassis dynamometer according to claim 1, wherein the speed control in the exhaust gas fuel consumption test mode is executed by an automatic speed maintenance control function of the chassis dynamometer. A vehicle loss measurement method in a chassis dynamometer that performs various tests of a vehicle under test mounted on a roller,
An operation control step, wherein the control means sets the chassis dynamometer in a speed control mode, and performs operation control with a vehicle speed pattern in an exhaust gas fuel consumption test mode;
A calculating step for calculating a vehicle loss by subtracting the loss of the chassis dynamometer alone from the mechanical loss detected by the load cell of the chassis dynamometer during operation in the exhaust gas fuel consumption test mode;
A vehicle loss measuring method in a chassis dynamometer, comprising:   4. The step of warming up the chassis dynamometer and the vehicle under test in a state where the transmission of the vehicle under test is in a neutral state before executing the operation control step. The vehicle loss measurement method in the chassis dynamometer described in 1.   5. The vehicle loss measurement method for a chassis dynamometer according to claim 3, wherein the operation control step is executed by an automatic speed maintenance control function of the chassis dynamometer.