Measuring and testing – Dynamometers – Responsive to torque
Reexamination Certificate
1998-06-22
2002-02-12
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Dynamometers
Responsive to torque
Reexamination Certificate
active
06345542
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a running resistance control apparatus for a chassis dynamometer.
Generally, a chassis dynamometer is arranged to execute a drive simulation of a test vehicle so as to measure various characteristics such as exhaust gas characteristic and fuel consumption. Such a simulation is executed in a manner such as to set the test vehicle on the chassis dynamometer and to drive the test vehicle under a predetermined road running pattern while executing a running resistance control. In order to adapt the chassis dynamometer to various vehicles having various weights, the conventional chassis dynamometer employs an electric inertial control which electrically simulates various weights of test vehicles.
As shown in
FIG. 2
, a conventional chassis dynamometer comprises a roller
1
which is rotatably supported to a base and on which driving wheels of a test vehicle
2
are set. A dynamometer
3
is interconnected with the roller
1
and is arranged to absorb a rotational power of the roller
1
rotated by the driving of the test vehicle
2
. A load cell
4
detects an absorption torque of the dynamometer
3
. A scale-up section
5
scales up an output of the load cell
4
from a millivolt (mV) unit to a volt (V) unit. A pulse pickup
6
detects a rotation speed of the dynamometer
3
which speed corresponds to a vehicle speed of the test vehicle
2
. An output pulse indicative of the vehicle speed
2
is outputted from the pulse pickup
6
to a frequency modulating section
7
(frequency modulator) where the output pulse is converted into a corresponding voltage value.
A running resistance setting section
8
connected to the frequency modulating section
7
outputs a running resistance torque R
RL
corresponding to the input voltage on the basis of a predetermined relationship between the vehicle speed and a running resistance torque. A mechanical-loss setting section
9
receives the vehicle-speed indicative voltage and outputs a mechanical-loss torque F
ML
corresponding to the vehicle speed on the basis of the predetermined relationship between the vehicle speed and the mechanical-loss torque. An electric inertia setting section
10
is constituted by a differential calculating section
11
and an electric inertia calculating section
12
. The differential calculating section
11
obtains an acceleration speed dv/dt of the vehicle
2
by differentiating the output of the frequency modulating section
7
. The electric inertia calculating section
12
calculates an electric inertia torque F
E
=(W
car
−W
o
)dv/dt from an output of an inertia setting section
13
for setting an weight W
car
of the vehicle
2
and the output of the differential calculating section
11
wherein W
o
is a mechanical inertia of the roller
1
and the dynamometer
3
which is previously stored.
An adding and subtracting section
14
adds the electric inertia torque F
E
to the running resistance torque F
RL
and subtracts the mechanical loss torque T
ML
from the sum of the electric inertia torque F
E
and the running resistance torque F
RL
. A difference detecting section
15
detects a difference between a torque command value which is an output of the adding and subtracting section
14
and a detection torque which is an output of the scale-up section
5
. A torque control section
16
is constituted by an amplifying section
17
for amplifying the output of the difference detecting section
15
, a phase control section
18
for outputting a phase control signal according to the output of the amplifying section
17
and a rectifier
19
which is turned on and off according to the phase control signal. The torque control section
16
controls an AC electric source by means of the Lenard control or inverter control and supplies the controlled voltage to the dynamometer
3
.
FIG. 3
shows a conventional running resistance control apparatus wherein the running resistance setting section
8
sets the running resistance torque F
RL
according to the detected vehicle speed V of the test vehicle
2
and outputs it. The mechanical loss setting section
9
sets the mechanical loss F
ML
according to the detected vehicle speed V and outputs it. The differential calculating section
11
obtains the acceleration speed of the vehicle
2
by differentiating the detected vehicle speed V. The electric inertia calculating section
12
calculates the electric inertia torque F
E
from the output of the differential calculating section
11
, the vehicle weight W
car
and the mechanical inertia W
o
of the roller
1
and the dynamometer
3
by using the equation F
E
=(W
car
−W
o
)dv/dt. The adding and subtracting section
14
adds the running resistance torque F
RL
and the electric inertia torque F
E
and subtracts the mechanical loss torque F
ML
therefrom. The output of the adding and subtracting section
14
is inputted to a dynamometer torque control section
20
. The dynamometer torque control section
20
obtains the dynamometer control torque F
LC
and inputs it to an adding and subtracting section
24
. A chassis dynamometer
21
comprises a roller
1
and the dynamometer
3
and is represented by a fixed inertia section
22
constituted by an integral element of the mechanical inertia W
o
and a mechanical loss section
23
and the adding and subtracting section
24
. The adding and subtracting section
24
subtracts the dynamometer control torque F
LC
and the output of the mechanical loss section
23
from a drive torque F
car
corresponding to the vehicle weight W
car
.
However, the conventional running resistance control apparatus of a chassis dynamometer produces a control delay time of about 100 milliseconds during the electric inertia control. Therefore, the detected vehicle speed V generates a control error with respect to a target vehicle speed V
R
obtained under an ideal running condition of the vehicle
2
. As shown in
FIG. 4
, a continuous line shows a target vehicle speed V
R
which is obtained in case that the vehicle
2
ideally runs receiving the set running resistance. A dotted line shows the detected vehicle speed V affected by the delay of the electric inertia control. The relationship between the target vehicle speed V
R
and the detected vehicle speed V shown in
FIG. 4
is established when the set vehicle weight W
car
is greater than the fixed inertia. When the set vehicle weight W
car
is smaller than the fixed inertia, the acceleration and the deceleration of the vehicle speed inversely function as compared with the case that the set vehicle weight is greater than the fixed inertia. Due to the delay of the electric inertia control, the detection vehicle speed V during the acceleration and the deceleration generates the error with respect to the target vehicle speed. This error badly affects the result of the exhaust gas performance and the fuel consumption as compared with those in case that the vehicle
2
actually runs on a road.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved running resistance control apparatus of a chassis dynamometer which apparatus improves the responsibility of an electric inertia control and corresponds a vehicle speed during acceleration and deceleration to a target vehicle speed so as not to affect the fuel consumption and exhaust gas performance.
A running resistance control apparatus according to the present invention is for a chassis dynamometer which comprises a roller on which a test vehicle is set and a dynamometer connected to the roller. The running resistance control apparatus comprises a running resistance setting section which sets a running resistance torque of the test vehicle according to the detected vehicle speed of the test vehicle. A mechanical loss setting section sets a mechanical loss torque according to the detected vehicle speed of the test vehicle. A differential calculating section differentiates the detected vehicle speed of the test vehicle. An electric inertia calculating section calculates an electric inertia to
Maruki Toshimitsu
Suzuki Masahiko
Kabushiki Kaisha Meidensha
Thompson Jewel V.
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