Automobile test device

Abstract

To provide a testing device for an automobile capable of reproducing the power balance at the time of driving and braking during turning and running of a test vehicle by giving a setting value to a dynamometer while paying attention to the fact that turning is caused by a change in steering angle performed by a steering wheel operation.SOLUTION: A control unit Cu for controlling the loads on dynamometers Dm1 to Dm4 connected to wheel connection portions Wc1 to Wc4 of a test vehicle Tc includes a running resistance model 11 and a balance control unit 13. A dynamometer connected to a wheel connection portion that is steered is movable in a steering direction with steering. A testing device includes steering angle sensors 2a and 2b and a turning motion model 15 in which turning motion is modeled in association with the test vehicle's specifications Bs, vehicle speed, and steering angle δ. In addition to a calculation result of the running resistance model, a balance command value as a calculation result of the turning motion model is input to the balance control unit, and the loads are respectively determined in consideration of mutual balance control between the dynamometers based on the balance command value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a test apparatus for automobiles, and more particularly, to an apparatus capable of controlling the load of a dynamometer assuming a turning motion caused by steering of an automobile (test vehicle).

Background Art

[0002] For example, chassis dynamometers have been conventionally used for evaluation tests of exhaust gas and fuel consumption of automobiles such as motorcycles, passenger cars, and trucks. In the evaluation test, an equivalent load (running resistance) when the test vehicle actually runs on the road is applied to the test vehicle installed on the rollers in the test chamber by a dynamometer, and for example, the mode exhaust gas amount (g / km) and the fuel consumption value (km / L) are calculated (see, for example, Patent Documents 1 and 2). Such a chassis dynamometer is a mechanical device that does not assume turning the test vehicle. Therefore, it cannot meet the recent demand for conducting an evaluation test by a mode operation assuming an actual road including turning.

[0003] On the other hand, a test apparatus for automobiles has been proposed in which the tires of the test vehicle are removed, and for example, dynamometers are respectively connected to the hubs as the wheel connection portions of the test vehicle, and power is applied without passing through the rollers. Among such test apparatuses for automobiles, there is also a type in which the actual steering angle of the wheels can be changed by operating the steering wheel of the test vehicle (see Patent Document 3). In this type, it is possible to conduct an evaluation test of exhaust gas and fuel consumption based on the total of the driving force from the prime mover such as the engine or motor of the test vehicle to the hub, the regenerative energy, and the deceleration energy during braking operation during driving including turning.

[0004] However, when the test vehicle is steered during actual road driving, it undergoes various independent motions (see Non-Patent Documents 1 and 2). Along with this, although the balance of the driving resistances acting on each driving wheel and each driven wheel of the test vehicle changes, the above Patent Document 3 has a problem in that such a balance of driving resistances cannot be taken into account. That is, in mode driving assuming an actual road including turning, a forward fall test called front loading in an evaluation test in a test room including turning on a test course, an advanced driver assistance system (ADAS) when information typified by the external view of the vehicle can be simulated, or driving during autonomous driving (AD), when conducting an evaluation test without preset values such as a preset vehicle speed, there is no means for applying a preset value (load) to the dynamometer in advance for turning.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0006]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] The object of the present invention is to provide a test apparatus for an automobile that assigns a set value to a dynamometer by paying attention to the fact that turning is caused by a change in the steering angle performed by a steering operation, and can reproduce the power balance during driving and braking when the test vehicle is turning.

Means for Solving the Problems

[0008] In order to solve the above problems, the present invention includes: each dynamometer connected to the wheel connection part of the test vehicle; a control unit that controls the load of each dynamometer; and a vehicle speed detection means that detects the vehicle speed from the rotation speed of the dynamometer. The control unit includes a running resistance model that models the running resistance acting on the test vehicle corresponding to the specifications of the test vehicle set in advance and the vehicle speed of the test vehicle, and a balance control unit that determines the load applied to each dynamometer based on the calculation result of the running resistance model according to the vehicle speed detected by the vehicle speed detection means. In the test apparatus for an automobile in which each dynamometer is controlled according to the load determined by the balance control unit, and the dynamometer connected to the steered wheel connection part is movable in the steering direction along with steering, it further includes a steering angle sensor that detects the steering angle accompanying the steering of the test vehicle, and a turning motion model that models the turning motion when the test vehicle is steered corresponding to the specifications of the test vehicle, the vehicle speed, and the steering angle detected by the steering angle sensor. In addition to the calculation result of the running resistance model, a balance command value as the calculation result of the turning motion model is input to the balance control unit, and the load is determined by taking into account the balance control between the dynamometers based on this balance command value.

[0009] According to the above, when the test vehicle is turning, the steering angle can be detected and a set value (load) considering, for example, the differential rotation speed and differential torque, which are examples of the balance control of each driving wheel, can be applied to each dynamometer. Therefore, the power balance during driving and braking when the test vehicle is turning can be reproduced. In other words, since the set value for the dynamometer with respect to the steering angle is automatically applied, the evaluation test can be carried out even when the set value is unknown in advance.

[0010] Here, when the test vehicle turns by steering, the wheels located on the outside of the turning direction rotate faster than the wheels located on the inside. Therefore, when the steering angle increases, a deceleration torque called cornering drag is applied. Thus, in the present invention, it is possible to adopt a configuration in which the cornering drag is calculated by the turning motion model according to the steering angle detected by the steering angle sensor, and the calculation result is input into the running resistance model. Thereby, a set value (load) taking into account the cornering drag, which is the turning drag, can be applied to each dynamometer.

[0011] In the present invention, the turning motion model can adopt a configuration in which the equation of motion of the test vehicle during turning is modeled. Also, the balance command value can be given by any one of the vehicle speed following average rotation speed, the angular difference based on the travel distance difference, and the torque difference. Further, the steering angle sensor may be provided on all the wheels steered by the test vehicle. Also, as the dynamometer connected to something other than the steered wheels, a hub coupling type or a roller type that is immovable in the steering direction can be used. Further, instead of the steering angle at the steering angle sensor, the steering wheel angle of the test vehicle can be used. The object (test vehicle) that can be tested by the test apparatus for automobiles of the present invention is any one of a two-wheeled vehicle, a three-wheeled vehicle, a four-wheeled vehicle, a six-wheeled vehicle, an eight-wheeled vehicle, or a vehicle having a trailer, and includes some or all of its wheels. When the test vehicle is a two-wheeled vehicle, the camber angle can be detected to reproduce the cornering drag during turning, and thereby the front-rear differential rotation (balance) and the cornering drag during turning of the two-wheeled vehicle can be added to the dynamometer.

Brief Description of the Drawings

[0012]

Figure 1

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Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Modes for Carrying Out the Invention

[0013] Hereinafter, with reference to the drawings, an embodiment of the vehicle test apparatus TM of the present invention will be described using a four-wheel drive and front-wheel steering vehicle as the test vehicle Tc. In each drawing, unless otherwise specified, the same members, elements, and expressions are denoted by the same reference numerals and symbols, and terms indicating directions such as front, rear, up, and down are based on FIG. 1.

[0014] Referring to FIG. 1, the vehicle test apparatus TM of this embodiment includes dynamometers Dm1 to Dm4 connected to the wheel connection portions Wc1 to Wc4 of the test vehicle Tc, and a control unit Cu that controls the loads of the dynamometers Dm1 to Dm4. As the dynamometers Dm1 to Dm4, although they differ depending on the structure of the vehicle suspension device of the test vehicle Tc, known ones directly attached to the wheel connection portions Wc1 to Wc4, which are parts including brake disks and wheel hubs, can be used, and thus detailed description is omitted here. In this case, the dynamometers Dm1 and Dm2 connected to the wheel connection portions Wc1 and Wc2 of the steered front wheels are configured to be movable in the steering direction along with steering (steering wheel operation of the test vehicle Tc).

[0015] The control unit Cu models the running resistance (rolling resistance, air resistance, inertial resistance) acting on the test vehicle Tc corresponding to the specifications of the test vehicle Tc (as operation parameters) set in advance and the specifications of the tires that can be mounted on the test vehicle Tc (hereinafter referred to as "vehicle specifications Bs") and the vehicle speed V of the test vehicle Tc. Based on the calculation result of the running resistance model 11, a drive / brake direction model 12 that models the load distribution for each of the dynamometers Dm1 to Dm4 and the drive / brake direction of the test vehicle Tc, and a balance control unit 13 that determines the load applied to each of the dynamometers Dm1 to Dm4 based on the calculation result of the drive / brake direction model 12, and a vehicle speed detection means 14 that detects the vehicle speed of the test vehicle Tc. The rotation speed and torque measured by each of the dynamometers Dm1 to Dm4 are input to the drive / brake direction model 12, and the calculation result thereof is input to the vehicle speed detection means 14 to calculate the vehicle speed. Then, the load determined by the balance control unit 13 is input as a torque command to the power conversion devices Pc1 to Pc4 attached to each of the dynamometers Dm1 to Dm4, and each of the dynamometers Dm1 to Dm4 is load-controlled accordingly. Since known components can be used as the above components, further detailed description is omitted.

[0016] In the automotive test device TM of the present embodiment, in order to reproduce the power balance during drive / brake when the test vehicle Tc is turning, attention is paid to the fact that the turning of the test vehicle Tc is caused by a change in the steering angle performed by the steering operation, and the dynamometers Dm1 to Dm4 are configured to be able to apply a load (set value). This will be described in detail below. Known steering angle sensors 2a and 2b for detecting the steering angles δ1 and δ2 accompanying the steering of the test vehicle Tc are attached to the dynamometers Dm1 and Dm2 respectively connected to the wheel connection parts Wc1 and Wc2 of the front left and front right wheels to be steered. In this case, as long as the steering angles δ1 and δ2 can be detected, the mounting positions of the steering angle sensors 2a and 2b are not limited to this, and instead of the steering angles δ1 and δ2 at the steering angle sensors 2a and 2b, the steering operation angle of the test vehicle Tc can also be used.

[0017] In addition, the control unit Cu further includes a turning motion model 15 that models the turning motion when the test vehicle Tc is steered in correspondence with vehicle specifications Bs, vehicle speed V, and steering angles δ1 and δ2. The turning motion model 15 receives the vehicle speed V calculated by the vehicle speed detection means 14 and the steering angles δ1 and δ2 detected by the respective steering angle sensors 2a and 2b, and the calculation result in the turning motion model 15 is input to the balance control unit 13 as a balance command. Then, the balance control unit 13 determines the loads respectively, taking into account the balance control (differential rotational speed and differential torque) between the respective dynamometers Dm1 to Dm4 based on the balance command.

[0018] Next, with reference to FIG. 2, the calculation method for generating a balance command in the turning motion model 15 will be described by taking as an example a model based on the equation of motion of the test vehicle Tc during turning. Here, the turning motion model 15 includes a first turning model 15a, a second turning model 15b, and a coefficient calculation unit 15c. In the first turning model 15a, the vehicle speed V, which is a state quantity calculated by the vehicle speed detection means 14, and the average steering angle δ calculated from the steering angle δ1 detected by the left front wheel steering angle sensor 2a and the steering angle δ2 detected by the right front wheel steering angle sensor 2b are input. In addition, as vehicle specifications Bs, the wheelbase l, the length lf from the vehicle center of gravity point to the front wheels, the length lr from the vehicle center of gravity point to the rear wheels, the tread d, the vehicle weight m, the tire radius rt, the cornering power kf of the front wheels, and the cornering power kr of the rear wheels are preset, and from these, the coefficient A, which is a stability factor, is calculated and preset in advance by the coefficient calculation unit 15c. Then, the turning radius R is calculated from the coefficient A, the vehicle speed V, the wheelbase l, and the average steering angle δ, and the average steering angle δ, the turning radius R, the vehicle speed V, the tread d, and the tire radius rt obtained in the turning model 15a are input to the second turning model 15b, and the front wheel left - right rotational speed difference △Nfrl, the rear wheel left - right rotational speed difference △Nrrl, and the front - rear wheel rotational speed difference △Nfr caused by the turning motion of the test vehicle Tc are calculated, and these calculation results (△Nfrl, △Nrrl, △Nfr) are output to the balance control unit 13 as a balance command.

[0019] Next, with reference to FIG. 3, taking as an example the one modeled based on the equations of motion of the test vehicle Tc during turning travel, the method for calculating the cornering drag in the turning motion model 15 will be described. The turning motion model 15 also includes a third turning model 15d and a fourth turning model 15e. In the coefficient calculation unit 15c, each parameter of the vehicle specifications Bs is calculated in advance, and in addition to the coefficient A, the coefficient B is set. The third turning model 15d inputs the vehicle speed V, the average steering angle δ calculated from the steering angle δ1 detected by the front left wheel steering angle sensor 2a and the steering angle δ2 detected by the front right wheel steering angle sensor 2b, the wheelbase l, the length lf from the vehicle center of gravity point to the front wheels, the length lr from the vehicle center of gravity point to the rear wheels, and the coefficients A and B, and calculates the vehicle sideslip angle β and the vehicle yaw moment γ. Furthermore, the front wheel sideslip angle βf and the rear wheel sideslip angle βr are calculated. Then, the front wheel sideslip angle βf and the rear wheel sideslip angle βr are input to the tire sideslip characteristic 151 of the fourth turning model 15e as the cornering drag calculation unit, and the cornering drag Rc as the calculation result is input to the running resistance model 11.

[0020] Here, from FIG. 4 showing the models of the sideslip angle βf of the steered front wheels, the side force Fs, the cornering force Fc, and the cornering drag Rc, when the side force Fs is vectorially decomposed, it becomes the cornering force Fc and the cornering drag Rc. Therefore, the tire sideslip characteristic 151 in FIG. 3 is an XY characteristic that outputs the side force Fs and the cornering force Fc corresponding to the front wheel sideslip angle βf (or the rear wheel sideslip angle βr). This characteristic function presets the relationship between the front wheel sideslip angle βf, the side force Fs, and the cornering force Fc obtained experimentally in advance as the tire characteristic function, and corrects the points between the measurement points according to the input front wheel sideslip angle βf to output the side force Ffs and the cornering force Ffc. In general commercial vehicles, the same tires may be used to equalize the wear of the tires due to rotation. Therefore, one type of this tire characteristic function may be prepared. However, when different tires are mounted on the front and rear wheels or when modeling considering characteristic changes such as tire wear, two types of this function may be prepared.

[0021] Regarding the rear wheels, the side force Frs and the cornering force Frc may be output by correcting the measurement points according to the lateral slip angle βr of the rear wheel tire. From the side force Ffs and the cornering force Ffc of the front wheels, the cornering drag Rfc of the front wheels is calculated, and similarly, the cornering drag Rrc of the rear wheels is calculated. The cornering drag Rc applied to the entire vehicle can be obtained by calculating it for all four wheels from the above two values. Note that since it is performed by the running resistance model 11 for the entire vehicle, it is input here. Generally, when the steering angles δ1 and δ2 are small, the front wheel lateral slip angle βf also becomes small, and since the side force Fs and the cornering force Fc are almost the same, the cornering drag Rc becomes almost zero. And when the steering angles δ1 and δ2 become large, the side force Fs increases accordingly, while the cornering force Fc decreases, and the cornering drag Rc increases, which has an impact on the drive and brake system tests. Note that "cornering drag" is often described as an increase in running resistance due to tire characteristics with respect to the above steering angle. On the other hand, regarding wind resistance, during turning, the projected cross-sectional area and the CD value of the vehicle change, which affects the increase in running resistance. Also in this case, based on the vehicle lateral slip angle β, it may be applied to the dynamometer as an increase in running resistance against the wind from an oblique direction. This increase in wind resistance can also be regarded as cornering drag in a broad sense. However, to implement this model, it is necessary to obtain characteristic values with a small number of wind tunnel test devices, but there is not much data available, so in practice, it depends on the availability of such data.

[0022] Next, in order to explain the vehicle motion model of the test vehicle Tc, FIG. 5 shows an equivalent two-wheel model of a four-wheel vehicle, from which various quantities related to turning can be derived. In FIG. 5, as tire characteristics, βf is the front wheel slip angle, βr is the rear wheel slip angle, Ff is the cornering force of the front wheel, and Fr is the cornering force of the rear wheel. Also, as vehicle body motions, δ is the steering angle, β is the vehicle slip angle, γ is the vehicle yaw moment, and V is the vehicle speed. As vehicle specifications, l is the wheelbase, lf is the distance between the vehicle center of gravity point G and the front wheel axle, lr is the distance between the vehicle center of gravity point G and the rear wheel axle, m is the vehicle weight, and J is the vehicle yaw inertia moment. Note that when solving for turning, the centrifugal force and the camber thrust are related to the roll direction during turning. However, in this embodiment, since the vehicle motion model itself during vehicle turning is already known, the camber for four wheels is omitted, and only an example when solved from the motion in the vehicle yaw direction is described.

[0023] From the above specifications and state quantities, the equations of motion are as follows. That is, the yaw moment γ at the vehicle center of gravity point G is from Equation 1, the equation in the vehicle transverse axis direction at the vehicle center of gravity point G is from Equation 2, and the relationship between the steering angle δ, the vehicle slip angle β, the front wheel slip angle βf, and the rear wheel slip angle βr is calculated by Equation 3. Equation 1

[0024] TIFF0007697864000001.tif10168 Equation 2

[0025] TIFF0007697864000002.tif11168 Equation 3

[0026] TIFF0007697864000003.tif35168

[0027] Summarizing the coefficients A and B obtained from the parameters corresponding to the above specifications first, it becomes Equation 4. Note that the coefficient A is a parameter generally called the stability factor Sf. Equation 4

[0028] TIFF0007697864000004.tif24168

[0029] From the above, for the steady state where dV / dt = 0, dβ / dt = 0, and dγ / dt = 0, when obtaining the vehicle side slip angle β and the vehicle yaw moment γ, the following Equation 5 is obtained. Equation 5

[0030] TIFF0007697864000005.tif24168

[0031] From the above Equation 5, the turning radius R becomes the following Equation 6. Equation 6

[0032] TIFF0007697864000006.tif11168

[0033] Next, with reference to FIG. 6, in order to explain the fourth turning model 15e in FIG. 3, the turning radius of the test vehicle Tc and the difference in the number of revolutions of the left and right wheels, which is an example of balance control, will be described. In FIG. 6, R is the turning radius, R' is the inner wheel turning radius, d is the vehicle tread, θ is the turning angle, L1 is the running distance of the inner wheel, L2 is the running distance of the outer wheel, ΔL is the difference in the running distances of the inner and outer wheels, V is the speed, ΔV is the difference in the speeds of the inner and outer wheels, V - ΔV / 2 is the speed of the inner wheel, V + ΔV / 2 is the speed of the outer wheel, and ω is the angular velocity. Also, let the tire radius be rt. And let the time until the running difference of ΔL is generated be Δt, and the difference in the speeds of the inner and outer wheels ΔV is obtained from the following Equation 7. Equation 7

[0034] TIFF0007697864000007.tif35168

[0035] For the conversion of the difference in the speeds of the inner and outer wheels ΔV to the difference in the number of revolutions of the left and right wheels ΔNrl, the following Equation 8 is used. Note that since the difference in the turning radii is the same for the front left and right wheels and the rear left and right wheels, the difference in the number of revolutions of the left and right wheels ΔNrl is also the same. Equation 8

[0036] TIFF0007697864000008.tif10168

[0037] The difference in the number of revolutions of the front and rear wheels ΔNfr is geometrically approximated by the following Equation 9 from the difference in the turning radii in the same manner. Equation 9

[0038] TIFF0007697864000009.tif10168

[0039] Here, in the above, the vehicle side slip angle β and the vehicle yaw moment γ were calculated for the steady state where dV / dt = 0, dβ / dt = 0, and dγ / dt = 0. However, they can be calculated in real time by an arithmetic unit to obtain values including transients. Then, substituting the front wheel side slip angle βf and the rear wheel side slip angle βr into the above-described front wheel cornering force Ff and rear wheel cornering force Fr, substituting these into the above equations 1 and 2, and integrating all terms, equations 10 and 11 are obtained. Equation 10

[0040] TIFF0007697864000010.tif10168 Equation 11

[0041] TIFF0007697864000011.tif10168

[0042] In the above equations 10 and 11, s is the Laplace operator, and 1 / s has the same meaning as the integral symbol. When the above is represented by a block diagram, the whole becomes Figure 7, where the above equation 10 is the vehicle side slip angle model and equation 11 is the yaw moment model. Also, when describing the details of the vehicle side slip angle model according to equation 10, it is as shown in Figure 8(a). When describing the details of the yaw moment model according to equation 11, it is as shown in Figure 8(b). Furthermore, the turning radius model is as shown in Figure 8(c). Thus, if the first turning model 15a is replaced with the dynamic vehicle turning models of Figures 7 and 8(a) to (c), the dynamic front wheel side slip angle βf, rear wheel side slip angle βr, turning radius R, vehicle side slip angle β, and vehicle yaw moment γ can be obtained respectively.

[0043] According to the above embodiment, during the turning running of the test vehicle Tc, the steering angle δ can be detected and set values (loads) taking into account, for example, the differential rotational speed and differential torque, which are examples of the balance control of each wheel, can be applied to each of the dynamometers Dm1 to Dm4. Therefore, the power balance during driving and braking during the turning running of the test vehicle Tc can be reproduced. In other words, since the set values for the dynamometers Dm1 to Dm4 with respect to the steering angle δ can be automatically applied, the evaluation test can be carried out even in a state where the set values are unknown in advance.

[0044] As described above, embodiments of the present invention have been explained. However, various modifications are possible without departing from the scope of the technical idea of the present invention. In the above embodiment, the set value of the balance control assumes the passive differential gear of the test vehicle Tc, and it has been explained in terms of the differential rotation speed setting as a representative state quantity and the balance control of its dynamometer control system, but it is not limited thereto. For example, differences such as differences in the differential mechanism and the presence or absence of active vehicle control are related. However, even in this case, since the travel distance difference and differential rotation speed of each wheel obtained from the steering angle δ during steering do not change, the balance setting on the transmission side is output as it is, and on the receiving side, the control system of the balance control side may be made to correspond so that the vehicle difference becomes the same as that during actual running.

[0045] Also, in the above embodiment, an example has been described by taking a four-wheel drive and front-wheel steering type automobile as the test vehicle Tc, but it is not limited thereto. For example, the present invention can also be applied to two-wheel drive automobiles. In recent years, when brakes such as ABS (antilock brake system), TRC (traction control), and ESC (anti-skid device), which are standardly adopted as preventive safety technologies for vehicle stability devices, are controlled in automobiles, the present invention can also be applied. The driven wheels are the driving wheels, and the non-driven wheels are the follower wheels. When the test vehicle (actual vehicle) is running on the actual road, the follower wheels also rotate because they are in contact with the road surface. In this case, when evaluating and testing using the test device TM for automobiles of the present invention, since there is no road surface, if the follower wheels are not rotated to have the same vehicle speed as the driving wheels, the vehicle stability device will determine it as wheel spin and abnormal and the vehicle cannot be driven. In such a case, as shown in FIG. 9, the dynamometers Dm3 and Dm4 connected to the follower wheel connection part are also rotationally controlled to have the same vehicle speed as the driving wheels so that the vehicle stability device does not determine it as abnormal and the vehicle can be driven. Such a control function of the dynamometers Dm3 and Dm4 is referred to as a "vehicle speed following control unit". However, if a test can be performed by disabling the vehicle stability device and a desired evaluation can be obtained, a dynamometer may be prepared only for the driving wheels (front-wheel drive two wheels or rear-wheel drive two wheels). In addition, the control system may also be switched for load distribution for two-wheel drive. These control functions may be provided in the load distribution part of the above load distribution and tire drive control direction model.

[0046] Furthermore, in the above embodiment, as an example of the balance command, the difference ΔNfrl between the left and right rotational speeds of the front wheels, the difference ΔNrrl between the left and right rotational speeds of the rear wheels, and the difference ΔNfr between the rotational speeds of the front and rear wheels were taken as examples for explanation. This assumes the case where the differential mechanism of the vehicle is a differential gear and is generally performed when the vehicle side does not perform control. When the differential mechanism is other than a differential gear or the vehicle side performs balance control of each wheel such as active yaw control, the balance command is not limited to the rotational speed, but gives a model of the angular difference or torque difference based on the travel distance difference. Alternatively, the balance control may be disabled and the evaluation test may be performed only with the slip model in the drive / brake direction model of the tire.

[0047] Currently, the number of test vehicles is not very large, but even when the test vehicle Tc is a three-wheeled vehicle, similar to a four-wheeled vehicle, if the required number of dynamometers is prepared and a steering angle sensor is used for the front wheels, the evaluation test can be performed. Regarding such a test device for automobiles, FIG. 10(a) shows a configuration example for the "test vehicle Tc1" in the case of one front wheel and two rear wheels, and FIG. 10(b) shows a configuration example for the "test vehicle Tc2" in the case of two front wheels and one rear wheel. Also, in the case of a test for turning a two-wheeled vehicle (test vehicle Tc3) such as a motorcycle by the steering angle, as shown in FIG. 11(a), the required number of dynamometers Dm1 and Dm3 may be prepared in the same manner as above. However, as shown in FIG. 11(b), if the vehicle body is tilted and the turning is performed by the cornering force called the camber thrust corresponding to the angle called the camber angle by the test device for automobiles of the present invention, the dynamometer Dm2 used for this also needs to be angled corresponding to the camber angle. In such a case, a camber angle sensor may be provided and its output signal may be input to the turning model to enable the function. Note that since there is no differential mechanism between the front and rear wheels of the vehicle, balance control for its evaluation is unnecessary. Also, if it is desired to prevent ABS abnormality detection similar to a four-wheeled vehicle, vehicle speed tracking control and front-rear wheel balance control may be added, and a cornering drag load may be applied to perform an evaluation test of drive / brake during turning.

[0048] In addition, the present invention can be applied not only to four-wheel commercial vehicles such as buses and trucks, but also to vehicles with six or more wheels having a large number of trailing wheels. However, as shown in FIG. 12, for a trailer vehicle in which a tractor part having drive wheels and a trailer part are connected via a coupling device, the vehicle lateral slip angles β1 and β2 of the tractor part and the trailer part are not the same. Therefore, it is established by rewriting the "turning model (see FIGS. 2 and 3)" of the above embodiment for the trailer. In the case of a vehicle having a four-wheel steering function in a four-wheel vehicle, as shown in FIG. 13, if steering angle sensors 2c and 2d are also provided on the rear wheel side and input to the tire lateral force model and the turning motion model 15, the evaluation test can be similarly performed. In the vehicle motion model, if the rear wheel steering angle is set as δr in the formula of the rear wheel lateral slip angle βr in the same way as the front wheel steering angle δ in the formula of the front wheel lateral slip angle βf, the turning model can be similarly solved by the following formula 12. Formula 12

[0049] TIFF0007697864000012.tif7168

[0050] In addition, in the above embodiment, the dynamometers Dm1 to Dm4 connected to the wheel connecting portions (hubs) Wc1 to Wc4 and movable with respect to steering are described in the same manner for all wheels. However, for a dynamometer of a wheel axle that does not need to be movable with respect to steering, even if a hub-coupled dynamometer that does not move with respect to steering or a roller-type dynamometer independent on the left and right is combined, it is possible to provide balance control for each wheel and a cornering drag Rc. Further, even when a roller-type dynamometer that is not independent on the left and right is combined, although the balance control between the left and right cannot be achieved, it is possible to provide a cornering drag Rc. Further, if it is used for, for example, confirming the operation excluding the ESC of the vehicle stability device or the partial operation of other electronic control devices when steering in a state where the wheels are rotating without applying a load instead of evaluating the driving and braking forces, it functions as a test device for that purpose.

[0051] Furthermore, in the above-described embodiment, the steering angle is output from the dynamometers Dm1 to Dm4 that are movable in the steering direction (that is, the steering angle sensors 2a and 2b are provided on the dynamometers Dm1 to Dm4), but the steering angle of the wheel unit called the actual steering angle may be detected. Since steering is performed by the steering wheel, the power balance and the cornering drag Rc during turning can also be reproduced using the steering wheel steering angle as the steering angle. Note that a steering system called power assist that assists the driver's muscle strength is often used for steering. For example, in the case of the electric type shown in FIG. 14, the steering force is transmitted to the vehicle connection parts Wc1 and Wc2 by the mechanism of the steering wheel Hs, the motor, the reduction gear, the rack and pinion, and the steering shaft. Therefore, the ratio of the handle operation angle θ to the actual steering angle δ is approximately a constant reduction ratio G excluding the play angle in the steering system. In addition, an angle sensor (not shown) for detecting the angle of the steering wheel Hs is incorporated in the test vehicle Tc. The angle sensor is connected to a vehicle control device called an ECU and is connected by a communication system between ECUs called CAN in the test vehicle Tc. Angle data of the steering wheel Hs is assigned, and a part of it is connected to an in-vehicle diagnostic device called OBD outside the vehicle. The handle operation angle θ may be obtained by connecting the dynamometers Dm1 and Dm2 (their control units) and the ECU via the OBD port. Then, in the first turning model 15a, if the handle operation angle θ is gradually reduced at the reduction ratio G with the actual steering angle δ, it is used as the actual steering angle δ and input to the subsequent turning model 15b to control the dynamometers Dm1 and Dm2 during turning. In addition to the method of using the data of the control device of the test vehicle Tc as the handle operation angle θ, as shown in FIG. 15, a measuring instrument such as a steering angle meter may be attached without connecting to the ECU of the vehicle to detect the handle operation angle θ, output it as a signal, and connect it to the turning motion model 15.

Description of Symbols

[0052] TM…Automobile test device, Tc…Test vehicle, Wc1~Wc4…Wheel connection parts, Dm1~Dm4…Dynamometers, Cu…Control unit, 11…Running resistance model, Bs…Vehicle specifications, V…Vehicle speed, 13…Balance control unit, δ…Steering angle, 2a, 2b…Steering angle sensors, 15…Cornering motion model, θ…Steering wheel operation angle (steering wheel angle).

Claims

1. An automotive test apparatus comprising: dynamometers respectively connected to wheel connection parts of a test vehicle; a control unit for controlling the load of each dynamometer; and vehicle speed detection means for detecting the vehicle speed from the rotational speed of the dynamometer, wherein the control unit includes: a running resistance model that models the running resistance acting on the test vehicle in correspondence with the vehicle specifications of the test vehicle set in advance and the vehicle speed of the test vehicle; and a balance control unit that determines the load to be applied to each dynamometer based on the calculation result of the running resistance model corresponding to the vehicle speed detected by the vehicle speed detection means, and each dynamometer is controlled according to the load determined by the balance control unit, in a case where the dynamometer connected to the steerable wheel connection part is movable in the steering direction along with steering, further comprising: a steering angle sensor for detecting the steering angle accompanying the steering of the test vehicle; and a turning motion model that models the turning motion when the test vehicle is steered in correspondence with the vehicle specifications of the test vehicle, the vehicle speed, and the steering angle detected by the steering angle sensor, wherein a balance command value as the calculation result of the turning motion model is input to the balance control unit in addition to the calculation result of the running resistance model, and the load is determined for each dynamometer in consideration of the balance control between the dynamometers based on this balance command value, and the cornering drag is calculated by the turning motion model according to the steering angle detected by the steering angle sensor, and this calculation result is input to the running resistance model.

2. The automotive test apparatus according to claim 1, wherein the turning motion model models the equation of motion of the test vehicle during turning.

3. The automotive test apparatus according to claim 1 or claim 2, wherein the steering angle sensor is provided on all the wheels of the test vehicle that are steered.

4. The automotive test apparatus according to claim 1 or claim 2, wherein, as the dynamometer connected to a component other than the steered wheel, a hub coupling type or roller type that is immovable in the steering direction is used.

5. The automotive test apparatus according to any one of claims 1 to 4, wherein, instead of the steering angle by the steering angle sensor, the steering wheel angle of the test vehicle is used.

6. The test vehicle is any one of a two-wheeled vehicle, a three-wheeled vehicle, a four-wheeled vehicle, a six-wheeled vehicle, an eight-wheeled vehicle, or a vehicle having a trailer, and the automotive test device according to any one of claims 1 to 4.

7. The automotive test device according to claim 1, wherein when the test vehicle is a two-wheeled vehicle, a camber angle is detected to enable reproduction of cornering drag during turning travel.

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