JP2008298793A - Method for measuring engine inertia - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure inertia amount of an engine of a test object, with the engine connected to a dynamo of an engine test device, in relation to an engine inertia measurement method of measuring the inertiaal amount of an engine. <P>SOLUTION: While an engine is accelerated and decelerated with accelerations having absolute values equal to each other, by keeping slot opening at a predetermined value, characteristics of the engine and the dynamo are measured between the acceleration and the deceleration, and the inertia amount of the engine is obtained based on the measured characteristic values in the acceleration and the deceleration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an engine inertia measurement method for measuring an inertia amount of an engine.

    Conventionally, various engine performance tests, for example, in recent years, as a matter of interest, in order to conduct tests such as exhaust gas emission in the transient mode where the rotational speed and torque change from moment to moment, Bring the engine to the laboratory, etc., connect it to the dynamo on the ventilation, and change the engine's throttle opening, dynamo torque or rotational speed so that it conforms to the above transient mode, for example. Various performances and characteristics are measured.

  When operating such an engine test device to control the throttle opening and dynamo torque or rotational speed of the engine, the torque during acceleration or deceleration of the engine or dynamo is estimated and the value of those torques is estimated. Must be reflected in the control value. When estimating the torque of an engine or dynamo during acceleration (including deceleration), the acceleration is obtained by differentiating (or subtracting) the rotational speed command value that changes from time to time, and a predetermined engine is used as the acceleration. The engine or dynamo torque (torque for engine inertia or dynamo inertia acceleration) that accompanies acceleration (deceleration) is obtained by multiplying the inertia amount of dynamo and the inertia amount of dynamo, and the values of those torques are reflected Control values are used to control throttle opening, dynamo torque, or rotational speed.

    In recent years, as mentioned above, interest has shifted to the behavior of the engine in the transient mode from the previous steady mode (mode in which the rotational speed and torque are constant), and the engine performance has been accurately tested or reproducible. In order to perform a good test, it is necessary to accurately estimate the torque at the time of acceleration and input an accurate amount of inertia of the engine or dynamo and perform an accurate control.

Here, with respect to the dynamo, its inertial amount can be accurately measured, and usually an accurate value can be obtained from the manufacturer of the dynamo, but for the engine under test, the engine is still under development. Even if it is an engine, it can hardly be expected that an accurate measurement has been completed before being attached to the engine test apparatus. Therefore, conventionally, the weight W [kg] of the engine and the flywheel diameter D [m] of the engine, which are easy to measure with respect to the engine, are input to the engine test apparatus, and the engine inertia amount _{Ieg is set} to K as the proportionality coefficient. the ^{_{I eg [kgm 2] = W}} × D 2/4 × K ...... (1)
The calculation is performed by the following equation. For example, in some systems, K = 0.1 is fixedly set as an estimated value.

  However, the engine inertia amount obtained by this arithmetic expression is calculated using a coefficient K set in an estimated manner based on geometric dimensions and the like, and is not necessarily accurate. There is a problem that there are cases where it is not certain whether it can be performed or whether the test result has sufficient accuracy.

  In view of the above circumstances, an object of the present invention is to provide an engine inertia measurement method for measuring an inertia amount of an engine under test in a state where the engine to be tested is connected to a dynamo of an engine test apparatus.

An engine test apparatus comprising a dynamo to which the engine is connected, and performing an engine characteristic test while controlling the throttle opening of the engine connected to the dynamo and the torque and / or rotational speed of the dynamo. In an engine inertia measurement method for measuring an inertia amount of an engine,
A first step of accelerating and decelerating the engine while keeping the slot opening fully closed, and measuring characteristics of the engine and dynamo during the acceleration and deceleration;
The method includes a second step of obtaining an inertia amount of the engine based on the characteristic values during acceleration and deceleration measured in the first step.

In addition, the second step described above is performed by using the equation T _e = T _dy −M _loss + I _dy · Δω _e + I _eg · Δω _e
However, _Te : Engine generated torque [Nm]
T _dy : Dynamotorque [Nm]
I _dy : Dynamo inertial amount [kgm ² ]
I _eg : Engine inertia amount [kgm ² ]
M _loss : Mecharos
Δω _e : Rotational angular acceleration [rad / s ² ]
And the step of _obtaining the engine inertia amount _Ieg using the fact that the engine generated torque _Te is the same at the time of acceleration and deceleration at the same speed.

  As described above, according to the present invention, the engine inertia amount can be measured, and a highly accurate engine test can be performed as compared with the conventional one.

    Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a block diagram showing an embodiment of an engine test apparatus.

  An engine 10 to be tested is connected to a dynamo 30 via an output shaft. The output shaft 20 is provided with a shaft torque meter 40 for measuring the torque of the output shaft.

  A control unit that controls the engine 10 and the dynamo 30 includes an engine control unit 100 and a dynamo control unit 200.

  A rotational speed command value and a torque command value of a predetermined change pattern are stored in a personal computer (not shown), and the rotational speed command value that changes from moment to moment is stored in the personal computer or the like. The torque command value is input.

A rotational speed command value that changes from moment to moment is first input to the engine map storage unit 101. The engine map storage unit 101 stores an engine map representing the correspondence between the rotational speed and torque and the throttle opening. The rotation speed command value is input to the differential calculator 102 in addition to the engine map storage unit 101. The differential calculator 102 obtains the change (angular acceleration) Δω from the rotational speed command value. The angular acceleration Δω obtained by the differential calculator 102 is input to the multiplier 103. The multiplier 103 is preset with an engine inertia amount _Ieg , and the multiplier 103 multiplies the input angular acceleration Δω by the engine inertia amount _Ieg to obtain an engine inertia acceleration component torque Δω · I. _eg is determined. The obtained engine inertia acceleration component torque Δω · I _eg is input to the adder 104. The adder 104 also receives a torque command value, and the adder 104 adds the engine inertia acceleration torque Δω · I _eg obtained by the multiplier 103 and the torque command value to store the engine map. Input to the unit 101.

  From the engine map storage unit 101, the throttle opening corresponding to the input rotation speed command value and the torque added by the adder 104 is read out and input to the adder 105.

  The PID control unit 106 receives a rotation speed command value and a dynamo rotation measurement value representing the actually measured rotation speed. In the PID control unit 106, the dynamo rotation measurement value is the same as the rotation speed command value. A correction value of the throttle opening is obtained so as to be the value of and input to the adder 105. The adder 105 adds the throttle opening correction value obtained by the PID control unit 106 to the throttle opening read from the engine map storage unit 101 to obtain a throttle opening command value. Based on this, the throttle opening of the engine 10 is controlled.

Further, the rotational speed command value is also input to a differential calculator 202 provided in the dynamo control unit 200 to obtain an angular acceleration Δω and input to the multiplier 203. The multiplier 203 is preset with the inertia amount I _dy of the dynamo 30, and the multiplier 103 multiplies the input angular acceleration Δω by the dynamo inertia amount I _dy to generate the dynamo inertia acceleration component torque Δω · I _dy. Is required. This dynamo inertial acceleration torque Δω · I _dy is input to the subtractor 204 and subtracted from the torque command value which is the other input to the subtractor 204 to generate a torque reference value. The torque reference value is input to the PID control unit 206. The PID control unit 206 also receives a dynamo torque measurement value representing the actually measured torque of the dynamo 30, and the PID control unit 206 matches the torque measurement value with the torque reference value from the subtractor 204. The dynamo current command value is obtained so that The torque of the dynamo 30 is controlled by this dynamo current command value.

  The configuration of the engine control unit 100 and the dynamo control unit 200 in FIG. 1 described above is one example. For example, the throttle opening of the engine 10 is controlled by the configuration of FIG. In FIG. 1, torque is controlled, and various performances and characteristics of the engine are tested and measured during that time.

Here, as shown in the multiplier 103 and the multiplier 203, torque due to the inertia of the engine and dynamo at the time of acceleration (including the time of deceleration) is obtained based on the rotational speed command value and reflected in the control. , for this purpose, it is necessary to know the inertia weight I _eg of the engine and _dynamo, the I _dy advance. As described above, the dynamo inertial value I _dy can be known in advance, but the calculated value based on the above-described equation (1) has conventionally been adopted for the engine inertial value _Ieg. There was a risk of considerable errors. Therefore, here, a method of actually measuring the inertia amount of the engine 10 will be described.

  FIG. 2 is a diagram illustrating an example of a control system for actual measurement of the engine inertia amount of the engine test apparatus.

  Here, as schematically shown in FIG. 2, the rotational speed is increased at a constant acceleration to be a constant speed for a while, and then the rotational speed is decreased at a constant acceleration whose absolute value is the same as the acceleration at the time of increase. The rotational speed command value of the speed pattern is input.

  The rotation speed command value is input to the PID control unit 211. The PID controller 211 also receives a dynamo rotation measurement value, and controls the dynamo 30 to have a rotation speed corresponding to the rotation speed command value.

  During this time, the throttle opening command value for controlling the throttle opening of the engine 10 is held at the command value for instructing the throttle to be fully closed.

Next, the fact that the engine inertia amount _Ieg can be measured by employing the control system of FIG. 2 will be described.

The relational expression of transient torque is
T _e = T _dy −M _loss + I _dy · Δω _e + I _eg · Δω _e (2)
However,
T _e : Engine generated torque [Nm]
T _dy : Dynamo torque [Nm] (Dynamo absorption, drive torque)
I _dy : Dynamo inertia (including shaft torque meter, etc.) [kgm ² ]
I _eg : Engine inertia (including clutch, transmission, etc.)
[Kgm ² ]
M _loss : Mecharos
Δω _e : Rotational angular acceleration [rad / s ² ]
Can be expressed as Here, acceleration / deceleration is performed at a constant throttle opening and constant acceleration. At this time, the above equation (2) is
T _e 1 = T _dy 1−M _loss + I _dy · Δω _e 1 + I _eg · Δω _e 1 (during acceleration)
T _e 2 = T _dy 2−M _loss + I _dy · Δω _e 2 + I _eg · Δω _e 2 (during deceleration)
Can be expressed as Here, in the fuel cut state, T _e 1 and T _e 2 are friction loss torques, and T _e 1 = T _e 2 at the same rotation speed, and the expression (3) is established.

T _dy 1−M _loss + I _dy · Δω _e 1 + I _eg · Δω _e 1
= T _dy 2−M _loss + I _dy · Δω _e 2 + I _eg · Δω _e 2 (3)
Therefore, from the equation (3), the engine inertia value is obtained as follows.

In the above equation (4), the rotational angular accelerations Δω _e 1 and ω _e 2 during acceleration and deceleration can be obtained from the dynamo rotation measurement values, and dynamo torques T _dy 1 and T _dy 2 during acceleration and deceleration are obtained. Is the dynamo torque measurement value itself. Further, the dynamo inertia amount I _dy can obtain an accurate value as described above.

Therefore, the engine inertia amount _Ieg can be measured based on the equation (4).

  FIG. 3 is a diagram showing temporal changes in dynamo rotation speed, dynamo torque, and acceleration when the engine and dynamo are operated using the control system shown in FIG.

  The dynamo rotation speed increases at a constant acceleration, maintains a constant speed for a while, and then decreases at a constant acceleration.

  Fig. 4 shows the measured values of dynamo torque (acceleration and deceleration) and acceleration (acceleration and deceleration), and their measured values when the rotational speed is taken on the horizontal axis. It is the figure which showed the engine inertia quantity (the calculated value for every time, and the average value of a stable area | region) calculated | required by substituting.

From the measured values shown here, the engine inertia amount _Ieg is
I _eg = 4.08 [kgm ² ]
Is required.

  The engine to be tested at this time is an engine with a displacement of 13000 cc diesel engine 6-cylinder intercooler, and has an engine weight of 1200 kg and a flywheel diameter of 0.43 m.

By the way, for this engine, when the engine inertia amount _Ieg is obtained from the engine weight and the flywheel diameter according to the above-mentioned equation (1),
I _eg = 5.55 [kgm ² ]
It becomes.

  As shown in this example, the calculated value according to the above-described equation (1) is greatly deviated from the actual measured value.

It is a block diagram which shows the form of an engine test apparatus. It is a figure which shows an example of the control system for engine inertia amount actual measurement of an engine test apparatus. It is the figure which showed the time change of a dynamo rotational speed, a dynamo torque, and an acceleration when operating an engine and a dynamo using the control system shown in FIG. It is the figure which showed the measured value of dynamo torque and acceleration, and the calculated value of an engine inertia amount when a rotational speed is taken on a horizontal axis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 20 Output shaft 30 Dynamo 40 Axis torque meter 100 Engine control part 101 Engine map memory | storage part 102 Differentiation calculator 103 Multiplier 104 Adder 105 Adder 106 PID control part 200 Dynamo control part 202 Differentiation calculator 203 Multiplier 206 PID Control unit 211 PID control unit 212 Differential operation unit 213 Multiplier 214 Correction value calculation unit 215 Adder

Claims (2)

An dynamo to which the engine is connected is provided, and the engine test apparatus is used to perform a characteristic test of the engine while controlling the opening of the throttle of the engine connected to the dynamo and the torque and / or rotational speed of the dynamo. In an engine inertia measurement method for measuring an inertia amount of an engine,
A first step of accelerating and decelerating the engine while keeping the slot opening fully closed, and measuring characteristics of the engine and the dynamo during the acceleration and deceleration;
An engine inertia measurement method comprising: a second step of obtaining an inertia amount of the engine based on characteristic values during acceleration and deceleration measured in the first step. The second step comprises the equation T _e = T _dy −M _loss + I _dy · Δω _e + I _eg · Δω _e
However, _Te : Engine generated torque [Nm]
T _dy : Dynamotorque [Nm]
I _dy : Dynamo inertial amount [kgm ² ]
I _eg : Engine inertia amount [kgm ² ]
M _loss : Mecharos
Δω _e : Rotational angular acceleration [rad / s ² ]
The engine inertia amount I _eg is obtained by using the fact that the engine generated torque T _e is the same at the time of acceleration and deceleration at the same rotation speed. Engine inertia measurement method.

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