Electricity: motive power systems – Impact – mechanical shock – or vibration-producing motors
Reexamination Certificate
2000-10-18
2002-09-03
Ramirez, Nestor (Department: 2834)
Electricity: motive power systems
Impact, mechanical shock, or vibration-producing motors
C318S128000, C318S460000, C267S140150, C188S269000
Reexamination Certificate
active
06445149
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for controlling a vibrator. Particularly, the present invention relates to a method and an apparatus for controlling a pneumatic vibrator suited for actively suppressing vibrations from a vibration source such as a vehicle. And the present invention also relates to an electromagnetic vibrator controlling method and an electromagnetic vibrator suited for actively suppressing vibrations from a vibration source such as a vehicle.
One of such known pneumatic vibrators is shown as a damper in Japanese Patent Laid-open Publication (Heisei)11-230245 which comprises a mass member elastically supported by a mount attached to a vibrating object to be controlled, an air-tightly enclosed air chamber for changing its inner pressure to apply a vibrating force to the mass member, and a driving switch valve mounted across an air flow passage communicated with the air chamber for alternatively connecting to a negative pressure source and to the ambient pressure. The frequency and phase of vibration of the mass member can be controlled by operating the driving switch valve. As shown in
FIG. 19
, the air chamber of the damper
1
is communicated via the air flow passage
2
to the negative pressure source
3
such as an air intake port of an engine and the ambient pressure
4
. When the switch valve
5
mounted across the air flow passage
2
switches between the negative pressure source
3
and the ambient pressure
4
, the pressure in the air chamber can be varied to develop a desired level of vibrating force for vibrating the mass member. The switching action of the switch valve
5
for determining the vibrating force is controlled by changing the duty ratio of a control signal released from a driver
6
. Such a conventional pneumatic vibrator is simple in the construction using not an electromagnetic driving means as a vibrating means in the damper and its advantages include smaller size, lighter weight, and lower power consumption.
However, the conventional pneumatic vibrator permits a change in the pressure in the air chamber determined by the switch valve
5
switching between the two different pressure sources
3
and
4
to generate not only a frequency component corresponding to the switching frequency but also a higher frequency component which may decline the effect of suppressing vibrations. For compensation, a silencer such as a branch hose
7
is provided across the air flow passage
2
between the air chamber and the switch valve
5
for reducing a change in the pneumatic pressure over a range of frequencies except the frequencies of vibration to be suppressed.
The silencer such as the branch hose
7
also attenuate a desired frequency component of the pneumatic pressure to be used together with the undesired higher frequency component, hence decreasing the vibrating force of the vibrator.
FIG. 20
illustrates another conventional arrangement where a second electromagnetic valve
8
is provided across the air flow passage
2
for closing and opening the path between an air intake port
3
and a tank
3
a
arranged for stabilizing the negative pressure at the intake port
3
. While the switching action of the first electromagnetic valve
5
is controlled by a pulse signal of a duty ratio tailored to minimize the higher frequency component and released from a driver
9
, the closing and opening action of the second electromagnetic valve
8
is controlled by a signal of a duty ratio tailored to have an optimum level of the pneumatic pressure and released from the driver
9
, thus suppressing the higher frequency component while eliminating the use of a branch hose. However, although the branch hose is eliminated, it is mandatory to provide the second electromagnetic valve
8
and the driver
9
in a combination and to control both the two electromagnetic valves
5
and
8
at a time with more difficulty. According, as the cost for controlling is increased, a resultant vibrator will hardly be priced down and be disadvantageous on the use in a vehicle or the like.
A further conventional electromagnetic vibrator is known as comprising an electromagnetic damper having a yoke with electromagnets mounted to a mount attached to a vibration source such as a vehicle chassis and a mass member elastically joined to the yoke by a rubber elastic member, and a drive controlling means for feeding the electromagnets with an electric control signal to produce a driving force corresponding to the magnitude of the electric control signal. This conventional vibrator drives the electromagnets to vibrate the mass member for generating a vibrating force which is used to actively suppress vibrations at the vibration source.
More specifically as shown in
FIG. 21
, the electric control signal C in the conventional vibrator is produced by having an input pulse signal S, e.g. an output of a rotary pulse sensor of which the frequency is correlated to the frequency of vibrations at the vibration source, synchronized and shifted by &thgr; in phase, and provided with a duty ratio favorably correlated with a level of the control amplitude to correspond to the amplitude of vibrations at the vibration source. As the mass member is vibrated by a driving means receiving the electric control signal C, the vibration develops a driving force to suppress the vibrations on a vehicle.
However, in the electromagnetic vibrator, the turning on and off of the electric control signal may produce and add a higher frequency component to the driving signal of a reference frequency provided for driving the electromagnets, hence inhibiting the mass member from applying a desired level of the vibrating force.
FIG. 22
illustrates a conventional method of constructing the electric control signal C, which comprises producing a reference pulse signal P which is synchronized with an input pulse signal S and has such a duty ratio determined as to develop a minimum of higher frequency component, producing a carrier signal (not shown) of which the frequency is higher than that of a reference pulse signal P while substituting and correlating the control amplitude with the duty ratio to correspond to the amplitude of vibrations at the vibration source, and superimposing the carrier signal over the reference pulse signal P. Accordingly, the generation of a higher frequency component in addition to the reference frequency in the driving signal for driving the electromagnets can be attenuated by the reference pulse signal while the amplitude of the driving signal can be controlled by superimposing the carrier signal of which the duty ratio corresponds to the amplitude of vibrations at the vibration source.
However, when the duty ratio of the carrier signal component in the electric control signal C is lowered, it permits the current for driving the electromagnets to be declined due to the time constant of the electromagnets acting as an actuator in the electromagnetic driving means. This causes the relationship between the vibrating force for vibrating the mass member and the duty ratio of the carrier signal to be not linear with each other, hence failing to suppress the vibration to a desired level.
SUMMARY OF THE INVENTION
It is an object of the present invention to eliminate the above described problems and provide a vibrator controlling method and a vibrator for applying a desired level of the vibrating force while readily removing a high frequency component. It is another object of the present invention to provide a pneumatic vibrator controlling method and a pneumatic vibrator for applying a desired level of the vibrating force while removing a high frequency component at a low cost with the use of a simple arrangement having no silencer such as a branch hose provided across the air flow passage. It is another object of the present invention to provide an electromagnetic vibrator controlling method and an electromagnetic vibrator for applying a desired level of the vibrating force while readily removing a high frequency component.
For achievement of t
Ichikawa Hiroyuki
Muramatsu Atsushi
Jones Judson H.
Ramirez Nestor
Tokai Rubber Industries Ltd.
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