Measuring and testing – Vibration – Sensing apparatus
Reexamination Certificate
1999-06-02
2001-07-03
Noori, Max (Department: 2855)
Measuring and testing
Vibration
Sensing apparatus
C073S847000
Reexamination Certificate
active
06253620
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The invention relates to a device and a method for measuring dynamic torsional characteristics of a damper assembly that includes a damper unit operably disposed between input and output rotary members.
B. Description of the Background Art
In the prior art, measurement of torsion characteristics of a damper assembly has been performed to obtain static torsion characteristics of the damper assembly by applying torsional vibrations while the damper assembly is maintained in a stationary state. However, the damper assembly is typically used in an automotive vehicle and rotates during operation receiving torsional vibrations in a high frequency range of tens of hertz or more. In view of the above, rotational torsion measuring devices are increasingly being employed for measuring the dynamic torsional characteristics of damper assemblies under conditions close to the actual service conditions.
Description is now given of a manner of measuring dynamic torsional characteristics of a damper assembly by a rotational torsion measuring device with reference to
FIG. 6
, where the damper assembly is statically retained.
A damper assembly
100
includes an input rotary member
101
, an output rotary member
102
and a damper unit
103
. The damper assembly
100
is fixed to first and second fixing portions
111
and
112
in a rotational torsion measuring device. More specifically, the input rotary member
101
is fixed to the first fixing portion
111
, and the output rotary member
102
is fixed to the second fixing portion
112
. The input rotary member
101
is fixed to the first fixing portion
111
via a shaft
113
. After setting the damper assembly
100
in the rotational torsion measuring device as shown in
FIG. 6
, a vibrating (or fluctuating) torque, i.e., a torque for causing vibrations, is applied to the input rotary member
101
via the first fixing portion
111
, and a torque Ts and a torsion angle &thgr;s are measured, as shown in FIG.
7
.
According to the above rotational torsion measuring device, the torque Ts and torsion angle &thgr;s are measured within the measuring device as shown in FIG.
6
. Therefore, the determined torsion characteristics include characteristics of the measuring device itself. A sensor cannot be attached directly to the damper assembly
100
in the above described configuration. Therefore, the torque Ts of the shaft
113
is measured by a sensor such as a strain gauge, and the torsion angle &thgr;s is determined by measuring the angular displacement between the first and second fixing portions
111
and
112
. These measured values of the torque Ts and torsion angle &thgr;s do not provide complete or accurate indications of the actual damper torsion torque and damper torsion angle of the damper assembly
100
for many reasons, such as the reasons set forth below.
First, the torsion angle &thgr;s is a measurement of the difference in angular displacement between the first and second fixing portions
111
and
112
. This measurement includes possible rotary displacement of elements other than the input and output rotary members
101
and
102
. Further, the measured angular displacement includes displacement attributable to torque which results from inertia of the input rotary member
101
acting on the first fixing portion
111
that is measurable at the location of the sensor measuring the torque Ts. Therefore, the actual damper torsion torque of the damper assembly
100
may be smaller that the torque being measured. Accordingly, the torque applied to the input rotary member
101
increases in accordance with the inertia of the input rotary member
101
and increases variable angular acceleration thereof. Therefore, the torque Ts measured by the rotational torsion measuring device shown in
FIG. 6
is smaller than the actual damper torsion torque of the damper assembly
100
.
Since the conventional rotational torsion measuring device internally measures the torque and torsion angle as described above, the device cannot determine the torsion characteristics of the damper assembly itself, but can determine only the torsion characteristics containing vibration characteristics of the measuring device. In particular, when the vibrating inertia is large, the shaft has a low rigidity and/or the frequency of the vibrating torque is high, these facts significantly affect the result of measurement.
SUMMARY OF THE INVENTION
An object of the invention is to provide a measuring device and a measuring method for accurately measuring dynamic torsional characteristics of a damper assembly including a damper unit arranged between input and output rotary members.
In one aspect of the present invention, a measuring device is configured to measure dynamic torsional characteristics of a damper assembly that has a damper mechanism operably disposed between input and output rotary members of the damper assembly. The measuring device includes a vibrating means for supplying a vibrating torque to the input rotary member of the damper assembly and a first angular speed measuring sensor for measuring an angular speed (d&thgr;
1
/dt) of the input rotary member. Further, a second angular speed measuring sensor measures an angular speed (d&thgr;
2
/dt) of the output rotary member. A calculating means is configured to determine torque and angular displacement of the damper mechanism using measurements made by the first and second angular speed measuring sensors.
Preferably, the measuring device also includes a torque measuring sensor for measuring at least one of a torque (T
1
) transmitted to the input rotary member and a torque (T
2
) transmitted to the output rotary member. The calculating means includes: a first calculating unit for calculating a torsion angle (&thgr;) of the damper unit; a second calculating unit for calculating a torque (T) acting on the damper unit; and a third calculating unit for calculating angular acceleration (d
2
&thgr;
1
/dt
2
) of the input rotary member by differentiating the angular speed (d&thgr;
1
/dt) of the input rotary member, calculations of the first and second calculating units being based on measurements from the first and second angular speed measuring sensors and the torque measuring sensor. The first calculating unit calculates the torsion angle (&thgr;) of the damper unit by integrating a difference between the angular speed (d&thgr;
1
/dt) of the input rotary member and the angular speed (d&thgr;
2
/dt) of the output rotary member. The second calculating unit calculates the torque (T) acting on the damper unit by subtracting from the torque (T
1
) the product of a moment of inertia (I
1
) of the input rotary member and the angular acceleration (d
2
&thgr;
1
/dt
2
) of the input rotary member, as set forth by the equation:
{
T=T
1
−(
I
1
)×(
d
2
&thgr;
1
/dt
2
)}.
Preferably, the torque measuring sensor is a strain gauge fixed to a torsion shaft configured to support and apply torque to one of the input rotary member and the output rotary member of the damper unit.
Preferably, the torque measuring sensor is a magnetic pickup configured to sense motion of protrusions on an adjacent rotary member.
Alternatively, the measuring device further includes a torque measuring sensor for measuring at least one of a torque (T
1
) transmitted to the input rotary member and a torque (T
2
) transmitted to the output rotary member. The calculating means includes: a first calculating unit for calculating a torsion angle (&thgr;) of the damper unit; a second calculating unit for calculating a torque (T) acting on the damper unit; and a third calculating unit for calculating angular acceleration (d
2
&thgr;
1
/dt
2
) of the input rotary member by differentiating the angular speed (d&thgr;
1
/dt) of the input rotary member. Calculations of the first and second calculating units are based on measurements from the first and second angular speed measuring sensors and the torque measuring sensor. The first calculating unit calculates the torsion angle (&thgr;) of the d
Exedy Corporation
Noori Max
Shinjyu Global IP Counselors, LLP
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