JP2013015386A - Engine bench system control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a conventional problem of failure to startup at an engine bench system due to hunting of frequency axial torque detection value caused by a resonates due to spring characteristics of a clutch attached integrally with the engine, at engine startup by an engine starter when a torque frequency generated at the engine comes closer to a machine resonance frequency of the clutch.SOLUTION: A parameter is set for a torque control part to decrease a mechanical resonance point neighborhood gain of a torque current command to an engine. A shaft torque T12 at the torque current command for decrease is obtained by T12=(K12/s+C12)×(w2 -w1). Note; K12: coupling shaft spring property, C12: damping, w2: dynamometer angular speed, w1: engine angular speed.

Description

  The present invention relates to a control method for an engine bench system, and more particularly to control at the time of engine start.

  An engine bench system for measuring various characteristics of the engine is configured as shown in FIG. In the figure, an engine E / G is combined with a transmission T / M (with a clutch in the case of AT, MT, or MT) and directly connected to a dynamometer (dynamometer) DY via a shaft and a shaft torque ST. A throttle actuator ACT is connected to the engine E / G, and the engine is controlled by adjusting the throttle opening.

  The dynamometer DY is equipped with detectors such as a speed detector PP and a shaft torque meter ST, and a detection signal is subjected to a difference calculation with a torque command and input to the controller C. The controller C generates a torque current command based on the difference signal, and controls the dynamometer DY as a power absorber via the inverter IV. In addition, as for the shaft directly connected, even when the specimens are different engines, a common shaft installed as equipment is generally used.

  The control of the engine bench system as described above is known from Patent Document 1 and the like.

JP 2010-71772 A

  When starting the test of the engine E / G by the engine bench system shown in FIG. 5, the engine E / G is started by starting a starter (not shown), and the engine unit test is executed after confirming the start. At that time, the clutch in the transmission T / M is always in the engaged state, and the connected body from the engine E / G to the dynamometer DY becomes a starter start load, and the starter may not be started for the following reason. .

  FIG. 6 shows a start waveform by the engine starter. (A) is the number of revolutions, line E is the engine alone, line D is directly connected to the dynamometer DY, (b) is the shaft torque detection value detected by the shaft torque meter, (c) is the controller C In the generated torque current command, UL is an upper limit value, and LL is a lower limit value.

  A clutch is inserted between the engine E / G and the dynamometer DY in the coupling body of the machine at the time of starting the engine, and the clutch has a spring characteristic due to backlash and the like and has a mechanical resonance characteristic. . For this reason, in speed control by IP control, resonance occurs when the frequency of the torque generated by the engine becomes close to the mechanical resonance frequency by the clutch, and the detected value of the shaft torque is hunted as shown in FIG. Occurs. At the same time, the torque current command is saturated as shown in FIG.

  For the torque current command, a predetermined acceleration / deceleration limit is set as an upper limit value UL (absorption torque limit) and a lower limit value LL (driving torque limit) in the controller C, and the limit is generally a deceleration (absorption) limit. The side is set larger. For this reason, when a hunting phenomenon occurs, the average load torque of the engine is biased toward the absorption side, and as shown in FIG.

An object of the present invention is to provide a control method for an engine bench system that can further improve the torque control device shown in Patent Document 1 and facilitate start control at the time of engine start.

The present invention connects an engine whose opening is controlled by a throttle actuator and a dynamometer, inputs a shaft torque command and detected shaft torque to a torque control unit, and integrates the shaft torque command and shaft torque detection by the torque control unit. Calculate the dynamometer torque by the difference between the signal and the dynamometer torque obtained from the calculation means of the transfer function for the shaft torque, generate a torque current command from the calculated dynamometer torque, and control the dynamometer via the inverter In the engine bench system,
The calculation parameter of the torque control unit is set so as to lower the gain near the mechanical resonance point of the torque current command for the engine when the engine is started.

Further, in the present invention, the calculation of the torque current command for lowering the gain near the mechanical resonance point in the torque control unit, the shaft torque T12 at the time of torque current command generation,
T12 = (K12 / s + C12) × (w2 −w1)
It is characterized by being obtained by
Where K12: Coupling shaft spring characteristics, C12: Damping coefficient, w2: Dynamometer angular velocity, w1: Engine angular velocity,

  As described above, according to the present invention, the model physical value of the engine bench is set to the optimum value of the torque control parameter so that the gain near the mechanical resonance point of the torque current command with respect to the engine torque is lowered. Thereby, saturation of the torque current command at the time of engine start is suppressed, and the engine starter can easily start without failing.

The block diagram which shows embodiment of this invention. The gain characteristic figure of the engine torque-torque current command by shaft torque control. Mechanical system model diagram. It is a wave form diagram for explanation, (a) is a number of rotations, (b) is axial torque detection, and (c) is a torque current command. The schematic block diagram of an engine bench system. FIG. 6 is a start waveform diagram by an engine starter, in which (a) is a rotation speed, (b) is a shaft torque detection, and (c) is a torque current command.

In general, the mechanical system configuration of an engine hench system is expressed as a multi-inertia mechanical system model having two or more inertias. The present invention is directed to an engine hench system that can approximate a multi-inertia mechanical system model to a two-inertia system.
J1: Engine inertia moment
J2: Dynamometer moment of inertia
K12: Coupling shaft spring stiffness
T12: Coupling shaft torsion torque (shaft torque)
w1: Engine angular speed
w2: Dynamometer angular velocity
T2: Dynamometer torque (torque current command)
Then, assuming that the Laplace operator is s, the equation of motion of the engine bench is expressed by equations (1) to (3).
J1 x s x w1 = T12 (1)
T12 = K12 / s x (w2-w1) (2)
J2 x s x w2 = -T12 + T2 (3)
FIG. 2 shows the gain characteristic of the torque current command with respect to the engine torque. The line A is a general characteristic diagram, and the line B is the gain characteristic according to the present invention described later.
In the mechanical system of a general engine bench system indicated by line (a), it has a resonance point in the vicinity of about 9 Hz, which is an obstructive factor when starting the engine.

FIG. 1 shows an embodiment of the present invention. By using such a torque control circuit, torque control is performed so as to lower the gain near the resonance point while moving the resonance point as shown by the solid line B in FIG. Set parameters.
In FIG. 1, reference numeral 1 denotes a torque control unit (DYATR) in the controller, which receives the shaft torque command T12r and the shaft torque detection T12 detected by the shaft torque meter ST, and obtains the shaft dynamometer torque T2 from the equation (4). The dynamometer (mechanical system of the engine dynamometer) 3 is controlled via the inverter 2 as a torque current command.
T2 = (Ki / s) × (T12r−T12) − (Kp + s × Kd) / (f1 × s + 1) × T12 (4)
However, Ki, Kp, Kd, and f1 are torque control parameters.

  FIG. 3 shows a mechanical characteristic of the dynamometer 3 used in the present invention by a transfer function, which is a two-inertia mechanical system model. This mechanical system model has J1.T and J2.T as inputs and J1.w, K12T, and J2.w as outputs. 31 is a roller inertia moment element, and its output is outputted to the generalized plant as a roller angular velocity J1.w and also outputted to the subtracting means 36. Reference numeral 32 denotes a spring stiffness element, which receives the difference signal between the dynamo angular velocity and the roller angular velocity calculated by the subtracting means 36 and outputs it as a shaft torsion torque K12.T signal to the generalized plant. Output to. In the adding means 34, the rotational moment J1.T of the roller due to the vehicle driving force applied to the roller surface and the shaft torsion torque K12.T are added and input to the roller inertia moment element 31. Further, the subtracting means 35 obtains a difference signal between the input dynamo torque signal J2.T and the shaft torsion torque K12.T and outputs it to the dynamo inertia moment element 33. The dynamo inertia moment element 33 calculates the dynamo angular velocity J2.w based on the input signal and outputs it to the generalized plant and also to the subtracting means 36.

That is, FIG. 3 is a circuit equivalent to the equation (4), and outputs the torque deviation between the torque command value T12r of the dynamometer and the shaft torque detection T12 via the integrating means, and the output and (Kp + s × Kd) / ( Multiplying the difference from the output of the calculation means for calculating f1 × s + 1) by the shaft torque detection T12 becomes the shaft torque T2 and becomes the torque current command.
The torque control parameters Ki, Kp, Kd, and f1 used for the calculation are determined as follows.

When the closed loop characteristic polynomials of the expressions (1) to (3) and (4) are obtained, the fourth-order polynomial of the expression (5) is obtained.
P (s) = a4 * (s / wr) ⁴ + a3 * (s / wr) ³ + a2 (s / wr) ² + a1 * (s / wr) +1 (5)
However, wr is a mechanical resonance frequency and is obtained by wr = √ (K12 (1 / J1 + 1 / J2)). Further, a4, a3, a2, and a1 are coefficients of the characteristic polynomial of the fourth-order low-pass filter. For example, the Butterworth type is set as follows.
a4 = 1
a3 = 2.61312592975275
a2 = 3.41421356237309
a1 = 2.61312592975275
The parameters Ki, Kp, Kd, and f1 are obtained as follows with the mechanical resonance frequency wr as wr = √ (K12 (1 / J1 + 1 / J2)).
Ki = f Ki (a4, a3, a2, a1, J1, K12, J2) (6)
Kp = f Kp (a4, a3, a2, a1, J1, K12, J2) (7)
Kd = f Kd (a4, a3, a2, a1, J1, K12, J2) (8)
f1 = ff1 (a4, a3, a2, a1, J1, K12, J2) (9)
In the present invention, the parameter is determined based on (6) to (9), and the parameter that decreases the gain near the mechanical resonance point of the torque current command with respect to the engine torque is obtained. The parameters were as follows.
J1: x 0.5 to 2
J2: × 0.5 to 2
K12: x 0.5 to 2
Poly: butter, bessel, binomial
C12: 0.1 to 1.0
Further, by adding an arbitrary coefficient to the damping, the shaft torque T12 obtained by the equation (2) was obtained as the equation (10).
T12 = (K12 / s + C12) × (w2 −w1) (10)
That is, multiply the inertias J1, J2 and stiffness K12 by a predetermined coefficient, change the closed loop characteristics (2 filters) and the damping coefficient of the closed loop characteristics, and combine the parameters that decrease the gain to the gain shown by the solid line B in FIG. Got the characteristics.

FIG. 3 shows the starting characteristics according to the present invention, where (a) shows the rotational speed, line A is the dynamometer, line B is the engine, (b) is the shaft torque detection, (c) torque current command, and UL is Absorption torque limit, LL is a drive torque limit.
By setting the torque control parameter to lower the gain near the mechanical resonance point of the torque current command with respect to the engine torque, the saturation phenomenon in which the torque current command is limited by the limit value as shown in FIG. As shown in FIG. 3B, the average value of shaft torque detection approaches zero. As a result, as shown in FIG. 5A, a start failure by the engine starter is prevented.

1 ... Controller (torque controller)
2 ... Inverter 3 ... Mechanical system of engine bench system E / G ... Engine T / M ... Transmission ST ... Shaft torque meter DY ... Dynamometer (dynamometer)
PP ... Speed detection C ... Controller IV ... Inverter

Claims (2)

An engine whose opening is controlled by a throttle actuator and a dynamometer are connected, and the shaft torque command and the detected shaft torque are input to the torque control unit. In an engine bench system that calculates a dynamometer torque based on a difference in dynamometer torque obtained from a means for calculating a transfer function with respect to the torque, generates a torque current command from the calculated dynamometer torque, and controls a dynamometer via an inverter ,
A method for controlling an engine bench system, wherein a model physical value of an engine bench system of a torque control unit is set so as to lower a gain near a mechanical resonance point of a torque current command with respect to an engine torque when the engine is started. The calculation of the torque current command for lowering the gain near the mechanical resonance point in the torque control unit is performed by calculating the shaft torque T12 when generating the torque current command,
T12 = (K12 / s + C12) × (w2 −w1)
An engine bench system control method characterized in that
Where K12: Coupling shaft spring characteristics, C12: Damping coefficient, w2: Dynamometer angular velocity, w1: Engine angular velocity,

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