Abstract:
The present invention provides a map preparing method for an engine testing apparatus or a vehicle testing apparatus capable of preventing a peculiar driving state from being generated. The method includes varying a throttle valve from its fully closed position to its fully opened position while maintaining a constant engine rotation number, carrying out operation for storing an output torque N m  at that time using at least three kinds of different engine rotation numbers, determining each obtained torque curves A˜E as actual machine data, and preparing a map based on the actual machine date. The map is prepared by describing each of the torque curves A˜E on the same X-Y plane based on the actual machine data, converting actual machine data function for describing torque approximation curves a˜e with respect to throttle opening degrees (X axis) on the same X-Y plane while making approximations to the torque curves determining the existence of intersecting torque approximation curves a˜e and automatically correcting one of the torque approximation curves c which can be determined peculiar such that a value Y 1  of y-component of the torque approximation curve c which appears peculiar among the intersecting torque approximation curves b and c in the determining step assumes a median value Y 2 , Y 3  of values of y-components of the vertically adjacent torque approximation curves b and d.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an engine testing apparatus and further relates to a map preparing method for the engine testing apparatus or a vehicle testing apparatus. More particularly, the invention relates to a novel map preparation method in which learned data (actual machine data) or a learning map for determining a throttle (accelerator) opening degree, which is a target valve for controlling an engine under test or a vehicle under test, is defined as an exponential function or a multiple-degree equation function. Thereby, a peculiar point of the learned data is determined, and the particular point is automatically corrected when preparing the learning map. 
     The present invention further relates to a novel map preparation method that uses data from a torque curve obtained by varying the throttle valve from a fully closed position to a fully open position while maintaining a constant engine rotation number and that uses data from a torque curve obtained by varying the throttle valve from a fully open position while maintaining a constant engine rotation number. The data is used to prepare a learning map for determining a throttle (accelerator) opening degree which is a target value for controlling an engine under test of a vehicle under test. 
     DESCRIPTION OF THE PRIOR ART 
     A conventional vehicle simulation system carried out on a stage includes a function for learning an engine under test (simply “engine”, hereinafter), and a learning map is prepared from the learned data. The engine is controlled based on the learning map. 
     The learned data is prepared by varying the throttle valve with the engine at an arbitrary rotation number and by storing an output torque (see FIG.  6 ). FIG. 6 shows a torque curve (actual measured value) obtained by varying the throttle valve from a fully closed position to a fully open position while maintaining the engine rotation number at a constant value. From the torque curve, a torque value is determined at one point with respect to the throttle valve opening degree at a certain engine rotation number (e.g., 2000 rpm). 
     However, since torque curves A, B, C, D and E of various engine rotation numbers (1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm) intersect at a low throttle opening degree in some cases, a peculiar portion is generated in a learning map based on the learned data, and accuracy of the control is deteriorated. For example, a peculiar driving state in which the throttle is closed for acceleration is generated. A first invention has been accomplished in view of the above circumstances, and an object of the first invention is to provide a map preparing method for an engine testing apparatus or a vehicle testing apparatus capable of preventing a peculiar driving state from being generated. 
     A throttle valve is varied while maintaining an engine at an arbitrary rotation number (e.g., 1500 rpm), and an output torque curve at the arbitrary rotation number is stored. The obtained output curves are determined as learned data  40 , and the learning map is prepared based on the learned data  40  (see FIG.  8 ). Table  1  shows the learning map prepared by the conventional method. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 N m   
                 Rpm 1500 
                 Rpm 2000 
                 Rpm 2500 
                 Rpm 3000 
                 Rpm 3500 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 −40 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −35 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −30 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −25 
                 0 
                 0 
                 0 
                 163 
                 276 
               
               
                 −20 
                 0 
                 43 
                 110 
                 260 
                 343 
               
               
                 −15 
                 28 
                 132 
                 200 
                 325 
                 430 
               
               
                 −10 
                 80 
                 190 
                 279 
                 392 
                 460 
               
               
                 −5 
                 133 
                 242 
                 339 
                 407 
                 475 
               
               
                 0 
                 175 
                 295 
                 362 
                 430 
                 512 
               
               
                 20 
                 324 
                 430 
                 512 
                 587 
                 678 
               
               
                 40 
                 459 
                 558 
                 654 
                 737 
                 813 
               
               
                 60 
                 572 
                 678 
                 775 
                 888 
                 978 
               
               
                 80 
                 721 
                 813 
                 910 
                 1045 
                 1143 
               
               
                 100 
                 925 
                 1060 
                 1157 
                 1261 
                 1345 
               
               
                 120 
                 1359 
                 1525 
                 1524 
                 1592 
                 1675 
               
               
                 140 
                 4096 
                 4096 
                 4096 
                 3054 
                 2552 
               
               
                 160 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 180 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 200 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                   
               
             
          
         
       
     
     From the learning map of Table 1, an output torque (simply “torque”, hereinafter) is determined at one point with respect to a particular engine rotation number and a particular throttle opening degree. For example, when the target engine rotation number is 1700 rpm and the desired target torque N m  is 30, the throttle opening degree for generating the target torque N m  can be determined from the values 329, 464, 435 and 563 by referring to the learning map of Table 1. 
     Conventionally, the throttle opening degree is controlled by varying the throttle valve from the fully closed position to the fully opened position, and the throttle opening degree is increased stepwise, for example, at 5% increments. Whenever the throttle opening degree is increased by 5%, it is necessary to wait until the torque is stabilized. The torque value is stored when it is stabilized. 
     However, when the engine is held at a constant rotation number and the throttle openings are the same, a torque output resulting from a throttle valve operated in the opening direction differs from a torque output resulting from the throttle valve operated in the closing direction. On the other hand, the conventional learned data can be obtained only when the throttle valve is fixed and the torque is stabilized as described above. Therefore, it is not possible to obtain a learning map corresponding to a variation in speed during a running speed pattern of a driving mode. 
     For example, it can be found from FIG. 11 that actual vehicle data  38 , which exhibits variations in throttle opening degree of an actual vehicle running on a chassis dynamo based on a running speed pattern I of a driving mode, intersects data  39 , which is data simulated according to the conventional method. In FIG. 11, the pattern I is constituted by constant speed straight lines f, h, k, o, r, w, x, acceleration straight lines g, j, l, q and deceleration straight lines i, p, s and u. 
     That is, from FIG. 11, the following points can be found: 
     (1) For example, with respect to acceleration straight line j, data  38  does not coincide with data  39 . That is, since an output torque with respect to a throttle opening degree operated while referring to the learning map and a torque necessary for acceleration do not coincide with each other, data  39  is deviated higher than data  38  in the first half. In order to correct the deviation of vehicle speed, data  39  is deviated lower than the data  38  in the latter half. 
     (2) A reversal exists in the vertical relation between data  38  and data  39  in the case of the acceleration straight line j and the vertical relation between data  38  and data  39  in the case of the deceleration straight line p. 
     (3) The same phenomenon exists in the acceleration straight line g and the deceleration straight line s. 
     In this manner, since the accuracy of the simulation is poor, it is difficult to accurately drive an engine with respect to the running speed pattern I of the driving mode. 
     A second invention has been accomplished in view of the above circumstances, and an object of the second invention is to provide a map preparing method for an engine testing apparatus or a vehicle testing apparatus capable of enhancing the simulation accuracy. 
     To verify the performance of an automobile engine, there exists an engine testing apparatus comprising a dynamometer connected to an output section of an engine which is to be tested, a dynamo controller for controlling the dynamometer, and an actuator for controlling a throttle opening degree of the engine under test. The engine testing apparatus controls the dynamo controller and the actuator to adjust the output of the engine under test. 
     In the conventional engine testing apparatus, the rotation of the dynamometer is controlled by the dynamo controller, the throttle valve of the engine under test is controlled and operated, and the output torque of the engine under test is controlled, thereby simulating the actual vehicle running. 
     However, the conventional engine testing apparatus does not have a function for controlling the temperature of the peripheral portions of the engine under test such as engine cooling water temperature, fuel temperature, air intake temperature, exhaust gas temperature and lubricant temperature. Therefore, the temperature environment of an actual vehicle can not be reproduced, and engine behavior similar to the actual vehicle can not be obtained. Thus, high simulation accuracy can not be obtained. 
     A third invention has been accomplished in view of the above circumstances. The object of the third invention is to provide an engine testing apparatus capable of simulating an actual running vehicle with high accuracy. 
     SUMMARY OF THE INVENTION 
     The first invention comprises varying a throttle valve from the fully closed position to the fully open position while maintaining an engine at a constant rotation, carrying out an operation of storing an output torque using at least three different engine rotation numbers, determining torque curves for each of the engine rotation numbers as actual machine data, and preparing a map based on the actual machine date. The preparation of the map is characterized by describing each of the torque curves on the same X-Y plane when a map is prepared based on the actual machine data, converting actual machine data function for describing torque approximation curves with respect to throttle opening degrees (X axis) on the same X-Y plane while making approximations to the torque curves, determining the existence of intersecting torque approximation curves, and automatically correcting the torque approximation curve which is determined peculiar such that a value of a y-component of the peculiar torque approximation curve assumes a median value of the y-component of each of the vertically adjacent torque approximation curves. 
     The second invention comprises calculating an average value of throttle valve operating speed from variation of the throttle valve operation speed, determining the average value of the throttle valve operating speed obtained by the calculation as a representative value corresponding to the throttle valve operating speed in a driving mode, operating the throttle valve in a state where the engine rotation number is made constant by the representative value, describing the torque curves with a plurality of engine rotation numbers, and preparing a map for determining the throttle opening degree based on the obtained torque curves. 
     According to another aspect of the second invention, a map preparing method is provided. The map preparing method is used for an engine testing apparatus or a vehicle testing apparatus. The map preparing method comprises calculating an average value of the throttle valve opening direction and an average value of the throttle valve closing direction from variations of the throttle valve operation speed, determining the average value of the throttle valve opening direction obtained by the calculation as a representative value corresponding to the throttle valve operating in the throttle valve opening direction in a driving mode, operating the throttle valve in the opening direction in a state where the engine rotation number is held constant by the representative value and describing the torque curves with a plurality of different engine rotation numbers, and preparing a map of the throttle valve opening direction based on the obtained torque curves, determining the average value of the throttle valve in the throttle valve closing direction obtained by the calculation as a representative value corresponding to the throttle valve operating in the throttle valve closing direction in a driving mode, operating the throttle valve in the closing direction in a state where the engine rotation number is held constant by the representative value and describing the torque curves with a plurality of different engine rotation numbers, and preparing a map in the throttle valve closing direction based on the obtained torque curves. 
     According to the third invention, an engine testing apparatus is provided. The engine testing apparatus comprises a dynamometer connected to an output section of an engine which is to be tested, a dynamo controller for controlling the dynamometer, and an actuator for controlling a throttle opening degree of the engine under test. The dynamo controller and the actuator are controlled to adjust an output of the engine under test, wherein commands based on a temperature pattern obtained from temperature data of various portions of the engine while running an actual vehicle in accordance with a running pattern on a chassis dynamo from an apparatus for controlling the entire apparatus to various temperature adjusting devices provided around the engine under test. 
     An apparatus for controlling the engine testing apparatus outputs, for example, commands based on the temperature pattern obtained from temperature data of various portions of the actually running engine in accordance with the running pattern on the chassis dynamo to various temperature adjusting devices provided around the engine under test. Thus, it possible to reproduce the temperature environment of the actual vehicle and obtain an engine behavior similar to the actual vehicle. Therefore, high simulation accuracy can be obtained. 
     The commands based on the temperature pattern may be based on a virtual vehicle simulation. In this case, it is possible to arbitrarily carry out the simulation of a virtual vehicle by adding various conditions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a characteristic graph showing a torque approximation curve obtained by converting a torque curve with respect to a specific engine rotation number using an exponential function approximation method according to an embodiment of a first invention; 
     FIG. 2 is a characteristic graph showing torque approximation curves obtained by converting torque curves with respect to a plurality of engine rotation numbers into functions using the exponential function approximation method of FIG. 1; 
     FIG. 3 is a characteristic graph showing torque approximation curves utilized for preparing a learning map required for control in which intersecting portions generated at lower portions of the throttle opening degree are deleted according to the above embodiment; 
     FIG. 4 is a schematic view illustrating an engine testing apparatus according to the first, second and third inventions; 
     FIG. 5 is a characteristic graph showing torque approximation curves obtained by converting torque curves with respect to a plurality of engine rotation numbers using an exponential function approximation method according to another embodiment of the first invention; 
     FIG. 6 is a characteristic graph showing torque curves corresponding to actual machine data used in each of the embodiments; 
     FIG. 7 is a schematic view illustrating one example of a vehicle testing apparatus to which the first and second invention can be applied; 
     FIG. 8 is a graph showing learned data for preparing a learning map of an embodiment of the second invention and learned data for preparing a conventional learning map; 
     FIG. 9 is a graph showing a variation in throttle valve operation speed obtained from the actual vehicle running on a chassis dynamo based on a running speed pattern of a driving mode; 
     FIG. 10 is a graph relating data from an actual vehicle running at varying throttle opening degrees on the chassis dynamo to data simulated by the second invention; 
     FIG. 11 is a graph relating data from an actual vehicle data running at varying throttle opening degrees on the chassis dynamo to data simulated by a conventional method; 
     FIG. 12 is a schematic view showing a structure of a system for controlling temperature of a cooling tank of a radiator mounted to an engine under test; and 
     FIG. 13 is a block graph showing one example of a control system for an engine testing apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of a first invention is described below with reference to the drawings. 
     FIG. 1 shows a torque approximation curve a obtained by functionally converting a torque curve A, where the engine rotation number is 1000 rpm, among torque curves A, B, C, D, and E as actual machine data shown in FIG. 6 an using an exponential function approximation method. The torque curves A, B, C, D, and E can be obtained from an engine testing apparatus  1  (which will be described later) constituting a vehicle simulation system carried out on a stage. 
     In FIG. 2, torque approximation curves a, b, c, and d obtained by functionally converting torque curve A, where the engine rotation number is 1000 rpm, torque curve B where the engine rotation number is 1500 rpm, torque curve C where the engine rotation number is 2000 rpm, and torque curve D where the engine rotation number is 2500 rpm (see FIG.  6 ). The torque curves A, B, C, D and E are shown on the same X-Y plane. 
     Of the torque approximation curves b an c intersecting in FIG. 2, the torque approximation curve c is defined as a peculiar curve. Curve C is automatically corrected, and FIG. 3 shows a characteristic view of automatically corrected torque approximation curve c′. 
     FIG. 4 shows the engine testing apparatus  1 . In FIG. 4, an output shaft  2   a  of an engine  2  under test (simply “engine” hereinafter) and a driving shaft  3   a  of a dynamometer  3  are detachably connected to each other through a clutch  4 . A dynamo controller  3 ′ controls the dynamometer  3 . A throttle actuator  5  controls the throttle opening degree of the engine  2 . A computer  6  controls the dynamo controller  3 ′ and the throttle actuator  5  through an interface  7 . 
     Symbols  8  and  9  respectively represent a torque measuring device and a torque amplifier. Symbol  11  represents a clutch actuator. Symbol  12  represents a target vehicle speed pattern. 
     As a first step for preparing a learning map, actual machine data (learned data) is prepared. The actual machine data is raw data obtained by varying the engine condition on engine dynamo. That is, an operation for varying the throttle valve from the fully closed position to the fully opened position, while maintaining the engine rotation number at a constant and storing the output torque, is carried out at the following engine rotation numbers: 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm and 3000 rpm. The output torque is stored in the computer  6 . FIG. 6 shows torque curves A, B, C, D, and E described on the same X-Y plane. The obtained torque curves A, B, C, D, and E correspond to respective engine rotation numbers. 
     Next, in the first embodiment, the torque curves A, B, C, D, and E are functionally converted by an exponential function approximation method. 
     Next, it is determined whether torque approximation curves a, b, c, d (see FIG.  2 ), which are functionally converted and described on the same X-Y plane, are intersecting. As shown in FIG. 2, since the torque approximation curve e, which corresponds to the torque curve E, does not intersect with torque approximation curves a, b, c, d, the torque approximation curve e is omitted. 
     As shown in FIG. 2, it can be seen that the torque approximation curves b and c are intersecting at a low portion of the throttle opening degree. A value of the y-component of the torque approximation curve c is defined as Y 1 , wherein |Y 1 |=L. A value of the y-component of the torque approximation curve b is defined as Y 2 , wherein |Y 2 |=M. A value of the y-component of the torque approximation curve d is defined as Y 3 , wherein |Y 3 |=N. Herein, L&lt;M&lt;N. 
     One of the intersecting torque approximation curves b and c is defined as peculiar and automatically corrected. 
     FIG. 3 shows a case in which the torque approximation curve c is defined as peculiar, and it is automatically corrected. In this case, it is considered that the torque approximation curve c is sandwiched between the torque approximation curves b and c over the entire throttle opening degree (X axis) except peculiar portion (intersecting portion)  11  intersecting with the torque approximation curve b. 
     The torque approximation curve c is re-defined as a torque approximation curve c′ (see FIG. 3) such that the value of the y-component of the torque approximation curve c assume a median value of the torque approximation curves b and d sandwiching the torque approximation curve c, thereby carrying out the automatic correction. That is, as shown in FIG. 3, a value of the y-component of the torque approximation curve c′ is Y 4 , wherein |Y 4 |=R=(L+M)/2. 
     The intersecting portion  11  generated at the low portion of the throttle opening degree can be deleted, and it is possible to prepare a learning map necessary for control in which a peculiar portion  11  is deleted from all torque approximation curves a, b, c, d, angle. 
     From the learning map, a preferred target throttle (accelerator) opening degree for engine control can be determined. For example, when the target engine rotation number is 1700 rpm and the desired target torque N m  is 30, the throttle (accelerator) opening degree for generating from the target torque N m  can be determined from values of 329, 464, 435 and 563 by referring to the learning map shown in Table 2. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 N m   
                 rpm 1500 
                 rpm 2000 
                 rpm 2500 
                 rpm 3000 
                 rpm 3500 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 −40 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −35 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −30 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −25 
                 0 
                 0 
                 0 
                 165 
                 278 
               
               
                 −20 
                 0 
                 45 
                 112 
                 262 
                 345 
               
               
                 −15 
                 30 
                 135 
                 202 
                 330 
                 435 
               
               
                 −10 
                 82 
                 195 
                 284 
                 397 
                 465 
               
               
                 −5 
                 135 
                 247 
                 344 
                 412 
                 480 
               
               
                 0 
                 180 
                 300 
                 367 
                 435 
                 517 
               
               
                 20 
                 329 
                 435 
                 517 
                 592 
                 683 
               
               
                 40 
                 464 
                 563 
                 659 
                 742 
                 818 
               
               
                 60 
                 577 
                 683 
                 780 
                 893 
                 983 
               
               
                 80 
                 726 
                 818 
                 915 
                 1050 
                 1148 
               
               
                 100 
                 930 
                 1065 
                 1162 
                 1266 
                 1350 
               
               
                 120 
                 1364 
                 1530 
                 1529 
                 1597 
                 1680 
               
               
                 140 
                 4096 
                 4096 
                 4096 
                 3059 
                 2557 
               
               
                 160 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 180 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 200 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                   
               
             
          
         
       
     
     As another embodiment, the torque approximation curve b can be defined as peculiar, and this may be automatically corrected as shown in FIG.  5 . In this case, the torque approximation curve b is sandwiched between the torque approximation curves a and c over the entire throttle opening degree (X axis) except peculiar portion (intersecting portion)  11  intersecting with the torque approximation curve c. 
     In the above embodiment, a single peculiar portion (intersecting portion)  11  is illustrated. However, the present invention can also be applied to a case having a plurality of peculiar portions (intersecting portion). In this case, the above-described technique may be repeated by the number of the peculiar portions (intersecting portion) until the peculiar portions (intersecting portion) disappear. 
     In each of the above embodiments, the learning map preparing method is applied to the engine testing apparatus  1 . However, the first invention can also be applied to a vehicle testing apparatus using a chassis dynamometer. 
     FIG. 7 shows one example of a vehicle testing apparatus. Symbol  21  represents a rotation roller on which driving wheel  22   a  of a vehicle  22  under test is mounted. Symbol  23  represents a chassis dynamometer operatively connected to the rotation roller  21  through a shaft  24 . The chassis dynamometer  23  corresponds to the dynamometer  3  of the engine testing apparatus  1 . Symbol  25  represents a flywheel provided on a shaft  24 , and symbol  26  represents a speed sensor provided on the shaft  24 . The speed sensor  26  corresponds to a sensor (not shown) for outputting a rotation measurement value for the engine testing apparatus  1  shown in FIG.  4 . The sensor is provided in an engine  2  of the engine testing apparatus  1  shown in FIG.  4 . Symbol  27  represents a torque sensor provided in the chassis dynamometer  23 . The torque sensor  27  corresponds to the torque measuring device  8  of the engine testing apparatus  1 . Symbol  28  represents a running resistance generator for generating a target running resistance signal T corresponding to an actual running speed signal v sent from the speed sensor  26 . Symbol  29  represents a chassis dynamo controller for driving and controlling the chassis dynamometer  23  such that a running resistance (target running resistance) corresponding to the actual running speed is applied to the driving wheel  22   a  based on a difference signal between an actual running resistance signal t sent from the torque sensor  27  and a target running resistance signal T sent from the running resistance generator  28 . Symbol X represents a driver&#39;s aid display unit on which a set target driving pattern V o  (target vehicle speed pattern  12  in FIG. 4) and a variation of data position V showing a real time driving state (actual running speed signal v of current time sent from the speed sensor  26 ) are displayed for the driver of the vehicle. 
     As described above in accordance with the first invention, learning data (actual machine data), which are based on a learning map for determining a throttle (accelerator) opening degree which is a target value for controlling an engine under test or a vehicle test is defined as an exponential function or a multiple-degree equation function, thereby finding a peculiar point. The peculiar point is automatically corrected when preparing the learning map. Therefore, a map without peculiar portions (intersecting portion) can be made. As a result, the control accuracy is enhanced. 
     An embodiment of a second invention is described below. 
     FIG. 8 is a graph showing learned data for preparing a learning map of the second invention and learned data for preparing a conventional learning map. FIG. 4 shows the engine testing apparatus  1  constituting a vehicle simulation system carried out on a stage. FIG. 9 shows a variation in throttle valve operating speed obtained from the actual vehicle running on the chassis dynamo based on a running speed pattern J of a driving mode differing from a running speed pattern I of a driving mode employed in FIG.  11 . FIG. 10 shows the relation between the actual vehicle data  38  showing a variation in throttle opening degree in the actual vehicle running on the chassis dynamo and data  37  simulated by the present invention. 
     In FIG. 4, the output shaft  2   a  of the engine  2  under test (simply “engine” hereinafter) and the driving shaft  3   a  of the dynamometer  3  are detachably connected to each other through the clutch  4 . The dynamo controller  3 ′ controls the dynamometer  3 . The throttle actuator  5  controls the throttle opening degree of the engine  2 . The computer  6  controls the dynamo controller  3 ′ and the throttle actuator  5  through the interface  7 . 
     Symbols  8  and  9  respectively represent the torque measuring device and the torque amplifier. The symbol  10  represents a clutch actuator. 
     As a first step for preparing a learning map, a variation in operating speed of the throttle valve which opens and closes in association with the accelerator pedal is obtained from the actual vehicle running on the chassis dynamo in corresponding manner to variation in speed in the running speed pattern I of the driving mode. 
     For the sake of convenience, a method for obtaining the variation in the throttle valve operation speed and then, from this result, calculating the average value of the throttle valve opening direction and the average value of the throttle valve closing direction will be explained for a case in which it is obtained from the running speed pattern J of the simplified driving mode as shown in FIG. 9 not from the running speed pattern I of the driving mode shown in FIGS. 10 and 11. This is because even when the running speed pattern I is employed, the average value can be obtained by the same method. 
     In FIG. 9, the running speed pattern J is set to such a target value that the speed passes through a transient portion W of an acceleration (transient) straight  31  which varies straightly from an idling portion Q of a constant speed (steady) straight line  30 , and again reaches a constant speed portion E of a constant speed straight line  32 , and further reaches a transient portion R of a deceleration (transient) straight line  33  which straightly varies from the constant speed portion E. 
     During the actual vehicle running on the chassis dynamo, a variation of the throttle valve operating speed is obtained in corresponding manner to the variation in speed during the running speed pattern J. The symbol  34  represents variation data of the obtained throttle valve operating speed. 
     Next, the average value of the throttle valve opening direction and the average value of the throttle valve closing direction are calculated from the variation data  34 . 
     The average value S of the throttle valve opening direction is arithmetical average value obtained by dividing a total sum of data F 1 . . . F n  of portion higher than the horizontal axis X (Y &gt;O) by the number of data (n). 
     The average value G of the throttle valve closing direction is an arithmetic average value obtained by dividing a total sum of data P 1 . . . P m  of portion lower than the horizontal axis X (Y&lt;O) by the number of data (m). 
     The torque curve is obtained by operating the throttle valve in its opening direction (the throttle opening degree is continuously varied from 0 to 100%) in a state where the engine rotation number is kept constant (e.g., 1500 rpm) at the representative value S. That is, the throttle valve is varied from the fully closed position to the fully opened position at the constant speed shown with the representative value S, thereby obtaining the torque curve  35  shown in FIG.  8 . 
     Further, using a plurality of engine rotation numbers differing from 1500 rpm, torque curves (not shown) are obtained by the same method. For example, while maintaining the engine rotation number at 2000 rpm, the throttle valve is operated in the opening direction (the throttle opening degree is continuously varied from 0 to 100%) at the representative value S, and the torque curve is obtained. Based on the obtained torque curves, a map for the throttle valve opening direction is prepared. The following Table 3 is a prepared learning map. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 N m   
                 rpm 1500 
                 rpm 2000 
                 rpm 2500 
                 rpm 3000 
                 rpm 3500 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 −40 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −35 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −30 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −25 
                 0 
                 0 
                 0 
                 165 
                 278 
               
               
                 −20 
                 0 
                 45 
                 112 
                 262 
                 345 
               
               
                 −15 
                 30 
                 135 
                 202 
                 330 
                 435 
               
               
                 −10 
                 82 
                 195 
                 284 
                 397 
                 465 
               
               
                 −5 
                 132 
                 247 
                 344 
                 412 
                 480 
               
               
                 0 
                 180 
                 300 
                 367 
                 435 
                 517 
               
               
                 20 
                 329 
                 435 
                 517 
                 592 
                 683 
               
               
                 40 
                 464 
                 563 
                 659 
                 742 
                 818 
               
               
                 60 
                 577 
                 683 
                 780 
                 893 
                 983 
               
               
                 80 
                 726 
                 818 
                 915 
                 1050 
                 1148 
               
               
                 100 
                 930 
                 1065 
                 1162 
                 1266 
                 1350 
               
               
                 120 
                 1364 
                 1530 
                 1529 
                 1597 
                 1680 
               
               
                 140 
                 4096 
                 4096 
                 4096 
                 3059 
                 2557 
               
               
                 160 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 180 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 200 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                   
               
             
          
         
       
     
     On the other hand, the torque curve is obtained by operating the throttle valve in its closing direction at the representative value G in a state where the engine rotation number is kept constant (e.g., 1500 rpm). That is, the throttle valve is varied from the fully closed position to the fully opened position at the constant speed shown with the representative value G. Thereby, the throttle opening degree is continuously varied from 100 to 0%, and the torque curve  36  shown in FIG. 8 is obtained. In this case also, using a plurality of engine rotation number differing from 1500 rpm, torque curves (not shown) are obtained by the same method. 
     Based on the obtained torque curves, a map for the throttle valve closing direction is prepared. The following Table 4 is a prepared learning map. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 N m   
                 rpm 1500 
                 rpm 2000 
                 rpm 2500 
                 rpm 3000 
                 rpm 3500 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 −40 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −35 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −30 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 −25 
                 0 
                 0 
                 0 
                 153 
                 270 
               
               
                 −20 
                 0 
                 35 
                 102 
                 260 
                 337 
               
               
                 −15 
                 20 
                 125 
                 192 
                 320 
                 425 
               
               
                 −10 
                 72 
                 185 
                 274 
                 387 
                 415 
               
               
                 −5 
                 125 
                 237 
                 334 
                 402 
                 470 
               
               
                 0 
                 170 
                 290 
                 357 
                 425 
                 497 
               
               
                 20 
                 319 
                 425 
                 507 
                 582 
                 673 
               
               
                 40 
                 454 
                 553 
                 649 
                 732 
                 808 
               
               
                 60 
                 567 
                 673 
                 770 
                 883 
                 973 
               
               
                 80 
                 716 
                 808 
                 905 
                 1040 
                 1138 
               
               
                 100 
                 920 
                 1055 
                 1152 
                 1256 
                 1340 
               
               
                 120 
                 1354 
                 1520 
                 1519 
                 1587 
                 1670 
               
               
                 140 
                 4096 
                 4096 
                 4096 
                 3049 
                 2547 
               
               
                 160 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 180 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                 200 
                 4096 
                 4096 
                 4096 
                 4096 
                 4096 
               
               
                   
               
             
          
         
       
     
     In this manner, the throttle opening degree is outputted to control the engine  2  using the learning map for the throttle valve opening direction when the throttle valve is operated in the opening direction during the running speed pattern J, and using the learning map for the throttle valve closing direction when the throttle valve is operated in the closing direction. Therefore, it is possible to moderate the deviation of the throttle opening degree which is caused in the conventional technique, and high simulation accuracy can be obtained. 
     If this method is applied to the running speed pattern I shown in FIG. 10, the following information can be derived from FIG.  10 . In FIG. 10, elements having the same symbols as those shown in FIG. 11 are the same elements or similar elements. The symbol  38  represents actual vehicle data showing a variation of the throttle opening degree for the actual running on the chassis dynamo prepared based on the running speed pattern I of the driving mode. The symbol  37  represents data simulated by this invention. From FIG. 10, it can be found that data  37  almost coincide with data  38 . 
     That is, 
     (1) For example, the portion of data  37 , which corresponds to the acceleration straight line e, coincides with the portion of data  38 , which corresponds to the acceleration straight line e. This means that reproduction of the engine state is enhanced in the transient portion H. 
     (2) Similarly, for example, both data  37  and data  38 , which correspond to the deceleration straight line i, also coincide. 
     (3) The same phenomenon is generated also in the acceleration straight line b and the deceleration straight line  1 . 
     From the learning maps, a target throttle (accelerator) opening degree having high accuracy in engine control can be determined. For example, when the target engine rotation number is 1700 rpm, when the desired target torque N m  is 30, and when the throttle valve is operated in the opening direction, a value of the throttle (accelerator) opening degree for generating the target torque N m  can be determined from values of 329, 464, 435 and 563 by referring to the learning map shown in Table 3. On the other hand, when the target engine rotation number is 1700 rpm, when the desired target torque N m  is 30, and when the throttle valve is operated in the closing direction, a value of the throttle (accelerator) opening degree for generating the target torque N m  can be determined from values of 319, 454, 425 and 553 which are different from those when the throttle is operated in the opening direction by referring to the learning map of Table 4 instead of Table 3. 
     In each of the above embodiments, the learning map preparing method for the engine testing apparatus  1  is described. However, the first invention can also be applied to a vehicle testing apparatus using a chassis dynamometer. 
     FIG. 7 shows one example of the vehicle testing apparatus. The symbol  21  represents a rotation roller on which the driving wheel  22   a  of a vehicle  22  under test is mounted, and the symbol  23  represents a chassis dynamometer operatively connected to the rotation roller  21  through the shaft  24 . The chassis dynamometer  23  corresponds to the dynamometer  3  of the engine testing apparatus  1 . The symbol  25  represents a flywheel provided on a shaft  24 , and the symbol  26  represents a speed sensor provided on the shaft  24 . The speed sensor  26  corresponds to a sensor (not shown) for outputting a rotation measurement value for the engine testing apparatus  1  shown in FIG.  4 . The sensor is provided in an engine  2  of the engine testing apparatus  1  shown in FIG.  4 . The symbol  27  represents a torque sensor provided in the chassis dynamometer  23 . The torque sensor  27  corresponds to the torque measuring device  8  of the engine testing apparatus  1 . The symbol  28  represents a running resistance generator for generating a target running resistance signal T corresponding to an actual running speed signal v sent from the speed sensor  26 . The symbol  29  represents a chassis dynamo controller for driving and controlling the chassis dynamometer  23  such that a running resistance (target running resistance) corresponding to the actual running speed is applied to the driving wheel  22   a  based on a difference signal between an actual running resistance signal t sent from the torque sensor  27  and a target running resistance signal T sent from the running resistance generator  28 . The chassis dynamo controller  29  corresponds to the dynamo controller  3 ′ of the engine testing apparatus  1 . The symbol X represents a driver&#39;s aid display unit on which a set target driving pattern V o  (corresponding to running speed pattern I in FIGS. 10 and 11, and the running speed pattern J in FIG. 9) and a variation of data position V showing a real time driving state (actual running speed signal v of current time sent from the speed sensor  26 ) are displayed for the driver of the vehicle. 
     As described above, in accordance with the second embodiment, the average value of throttle valve operating speed is calculated from variation of the throttle valve operation speed. The average value of the throttle valve operating speed obtained by the calculation is determined as a representative value corresponding to the throttle valve operating speed in a driving mode. The throttle valve is operated in a state where the engine rotation number is made constant by the representative value. The torque curves are described by a plurality of different engine rotation numbers, and a map is prepared for determining the throttle opening degree based on the obtained torque curves. Therefore, it is possible to control the engine to a throttle valve opening degree corresponding to the throttle valve operating speed, and high simulation accuracy can be obtained. 
     In particular, the throttle valve is operated at the representative value of the throttle valve operating speed. The data for preparing the learning map is prepared by storing the torque curve when the throttle valve is operated from the fully closed position to the fully opened position at the representative value (constant speed) and by storing the torque curve when the throttle valve is operated from the fully open position to the fully closed position at the representative value (constant speed). Therefore, it is possible to control the engine by a throttle valve opening degree corresponding to both the throttle valve opening direction and closing direction, and high simulation accuracy can be obtained. 
     Next, an embodiment of a third invention is described with reference to the drawings. FIGS. 4,  12  and  13  show one embodiment of this invention. First, FIG. 4 schematically shows the engine testing apparatus I according to the third invention. In FIG. 4, the symbol 2 represents the engine under test, the symbol  3  represents the dynamometer connected to the output section of the engine under test. The dynamometer  3  is controlled by the dynamo controller  3 ′ . In this embodiment, the output shaft  2   a  of the engine  2  under test and the driving shaft  3   a  of the dynamometer  3  are detachably connected to each other through the clutch  4 . The symbol  10  represents the clutch actuator which drives clutch  4 . The symbol  5 ′ represents the throttle of the engine  2  under test, the throttle  5 ′ is driven by the throttle actuator  5 , and the opening degree of the throttle is controlled. The symbols  8  represents the torque sensor provided in the driving shaft  3   a  of the dynamometer  3 , and the symbol  9  represents the torque amplifier which appropriately amplifies the output of the torque sensor  9 . 
     The symbol  6  represents the computer as a simulator which controls the engine testing apparatus  1 , and symbol  41  represents a signal conditioner unit. The computer  6  performs a computation based on an input from an input apparatus (not shown) and based on signals from various sensor such as the torque sensor  8  provided in the apparatus. The computer outputs commands to various portions of the engine testing apparatus  1 . The signal conditioner unit  41  is an interface having an AD converting function and a DA converting function. The signal conditioner unit  41  AD-converts signals from various sensors such as a torque sensor  8 , DA-converts commands from the computer  6 , and output commands to various portion of the engine testing apparatus I such as the dynamo controller  3 ′, the clutch actuator  10  and the throttle actuator  5 . 
     The above-described structure is the same as that of the conventional engine testing apparatus. Characteristics of the third invention resides in that commands based on a temperature pattern are outputted to various temperature adjusting devices provided around the engine  2  under test from the computer  6  which controls the engine testing apparatus  1 . 
     FIG. 12 is a schematic view showing a system for controlling a temperature of a cooling tank of a radiator mounted to an engine  2  under test. 
     In FIG. 12, symbol  42  represents a radiator mounted to the engine  2  under test, and symbol  43  represents a radiator tank for cooling the radiator  42 . 
     The engine  2  under test and the radiator  42  are connected to each other through a water-sending pipe  45  for supplying cold water  44  from the radiator to the engine  2  under test and a water-returning pipe  47  for returning warm water  46  from the engine  2  to the radiator  42 . Symbol  48  represents a water-supplying pipe connected to the radiator tank  43 . The water-supplying pipe  48  is connected to a water source (not shown) and includes a solenoid valve  49 . Symbol  50  represents a water-discharging pipe connected to the radiator tank  43 . Symbol  51  represents a temperature adjusting device for outputting a signal for opening and closing the solenoid valve  49 . By appropriately opening or closing the solenoid valve  49 , the cold water from the water source is supplied to the radiator tank  43 , thereby cooling the radiator  42 . 
     FIG. 13 is a block diagram showing one example of a control system for the engine testing apparatus  1 . In FIG. 13, symbol  52  represents a target pattern generator which is provided in the computer  6  so as to output a target speed signal Vr for allowing the engine  2  under the test to run in the actual vehicle at a predetermined running pattern. Symbol  53  represents a simulation vehicle control system which converts a target speed signal Vr from the target pattern generator  52  into a control target torque and controls the torque control system  54  including the engine  2  under test, so that the engine  2  under test outputs in a state where the actual vehicle running is simulated. The structure and function of each of the target pattern generator  52  and the simulation vehicle control system  53  are the same as those of the conventional engine testing apparatus. 
     Symbol  55  represents a temperature control system for controlling the temperature of the engine cooling water  44  supplied to the engine  2  under test to a predetermined temperature. The temperature control system  55  includes a delay correction control circuit  56  for correcting a response delay of a measured temperature with respect to a temperature instruction value of the temperature adjusting device  51 . The temperature control system  55  further includes a temperature feedback controller  57 . A temperature target value Orl, which is outputted from the target pattern generator  52 , is inputted to the delay correction control circuit  56 . That is, the target pattern generator  52  outputs the temperature target value Orl to the temperature control system  55  in accordance with a time series temperature pattern (the horizontal axis shows time, and the vertical axis shows temperature (° C.)) shown with the symbol  58  in FIG.  12 . 
     The operation of the engine testing apparatus having the above-described structure is described. In the computer  6  which controls the engine testing apparatus  1 , a time series pattern (time series temperature pattern)  58  of a temperature of the engine cooling water obtained when the actual vehicle running was tested in accordance with the running pattern on the chassis dynamo is previously stored as a program. The time series temperature pattern  58  is inputted to the target pattern generator  52 , thereby outputting the temperature target value Orl of the engine cooling water  44 . The temperature target value Orl is inputted to the cooling water temperature control system  55 . Since the cooling water temperature control system  55  is provided with the delay correction control circuit  56 , the delay correction control circuit  56  early outputs a temperature target value Octl so as to correct the response delay of the measuring temperature with respect to the temperature instruction value of the temperature adjusting device  51 . 
     The temperature target value Octl, the current actually measured temperature Ta and a deviation Oe are PI-controlled for example by the temperature feedback controller  57 , and a control signal is outputted to the temperature adjusting device  51 . Based on this control signal, an opening signal or a closing signal is sent to the solenoid valve  49  from the temperature adjusting device  51 , and the temperature of the engine cooling water  44  is varied with time in the same way as that of the actual running test. 
     As explained above, temperatures around the engine  2  under test include the engine cooling water temperature, the fuel temperature, the air intake temperature, the exhaust gas temperature and the lubricant temperature. It is necessary to control these temperatures respectively, and there are provided temperature adjusting devices (not shown). Therefore, in FIG. 13, as shown with symbols  55 A,  55 B, . . . , if the temperature control systems, which respectively corresponds with the fuel temperature and the like are constituted in the same way as the temperature control system  55 , and if they are controlled in the same manner, it is possible to reproduce the temperature environment of the actual vehicle of the various portions around the engine  2  under the test, and the engine behavior close to the actual vehicle can be obtained. Therefore, high simulation accuracy can be obtained. 
     In the above embodiment, in regards to the temperature control systems  55  , 55 A,  55 B, . . ., commands based on the temperature pattern obtained from temperature data of various portions around the engine when the actual vehicle running is tested in accordance with the running pattern on the chassis dynamo are set, but a temperature pattern based on a virtual pattern may be set. In this case, it is possible to arbitrarily carry out the simulation of a virtual vehicle by adding various conditions. 
     As explained above, according to the engine testing apparatus described in claim 4, a temperature around the engine can be reproduced in the same way as the actual vehicle running on the chassis dynamo, the engine behavior is extremely close to the actual vehicle running, the accuracy of the simulation can be enhanced, and the engine performance can be tested in a state close to the actual case. 
     According to the engine testing apparatus described in claim 5, it is possible to simulate a virtual vehicle, and it is possible to utilize the test in design of various engine.