Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2000-06-28
2001-12-25
Rodriguez, Pam (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S136000, C188S378000
Reexamination Certificate
active
06332603
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for controlling an assembly mount.
2. Discussion of Background
From German Patent Document DE 40 21 039 C2, a hydraulically damping assembly mount for an internal-combustion engine is known. The mount is designed such that vibrations of the internal-combustion engine resulting from gas forces and inertial forces are uncoupled from the vehicle body. In the event of low-frequency relative movements of the assembly with respect to the vehicle body, an overflow mechanism becomes effective in the mount, which overflow mechanism connects the two fluid chambers of the assembly mount with one another and, as the result of the friction losses of the overflowing fluid, causes an additional damping of these vibrations.
Furthermore, assembly mounts are known whose spring rate can be changed for an adaptation to certain operating conditions of the assembly (such as idling).
SUMMARY OF THE INVENTION
It is an object of the invention to provide a process for controlling an assembly mount, by means of which low-frequency natural vibrations of the assembly can be counteracted in a targeted and effective manner, without any negative influence on the behavior at a higher-frequency excitation.
An important feature of the present invention is the prevention of a transient effect of the low-frequency natural vibration of the assembly as the result of a rapidly occurring detuning of the assembly mount. While, according to the state of the art, low-frequency natural vibrations of the assembly as such are reduced, the process according to the invention provides the generating of targeted “interference pulses” which counteract the arising of a natural vibration of the assembly. The use of such interference pulses is particularly effective in the initial phase of a beginning natural vibration of the assembly.
The duration of the interference pulses is limited to no more than one fifth of the vibration duration of the natural vibration of the assembly. The pulse duration preferably amounts to approximately one tenth of the vibration duration of the natural vibration in order to not significantly change the acoustic characteristics of the assembly mount.
The “pulse amplitude” is also decisive. In order to achieve the effect according to the invention, a raising or lowering of the spring rate of the assembly mount by at least the factor
5
is required. Preferably, a spring rate ratio of approximately 1 to 10 is endeavored.
The change of the spring rate can take place in the sense of a hardening of the assembly mount as well as a reduction of its spring rate for the duration of the interference pulse. Preferably, a hardening of the mount takes place because, for an optimal insulation of the vibrations generated by the assembly, the assembly mount in its initial condition always has a low rigidity. The rigidity of the assembly mount can be changed, for example, by a magneto-rheological fluid, as described, for example, in German Patent Application 197 11 689.2.
The detuning continuously takes place at a frequency which is higher than or equal to the natural frequency of the non-detuned system consisting of the assembly, the mount and the base. As the result, it is ensured that at least one interference pulse occurs during each vibration period of the natural vibration of the assembly.
As the result of the process according to the present invention, the adjusting forces are minimized. In addition, this process prevents an intermediate storage of potential energy and a drifting of the zero position of the characteristic curve of the assembly mount.
As an alternative to the periodic detuning of the assembly mount as a function of the inherent vibration of the assembly, the mount can also be detuned periodically at the frequency of the vibrations generated by the assembly. As the result, the damping behavior of the aggregate mount is influenced as little as possible with respect to its actual lay-out.
It is particularly advantageous to increase the spring rate in the range of the zero crossings of the vibrations generated by the assembly in order to achieve a minimal reaction of the assembly mount to the surrounding structure and thus not significantly impair the acoustic qualities of the assembly mount, as would be the case in the event of a hardening of the mount at correspondingly high vibration amplitudes of the vibrations generated by the assembly.
The interference pulses may also be entered stochastically, in which case the density of the pulse sequence is to be dimensioned such that at least one interference pulse falls into almost every vibration period of the aggregate vibration.
In a preferred application of the invention, the assembly mount is constructed as an engine mount in a motor vehicle and, for insulating the free gas forces and inertial forces of the engine, as a rule of an internal-combustion engine, is constructed to be correspondingly soft. In addition to these engine-caused vibrations, the engine also carries out low-frequency movements (stuttering vibrations) with the natural frequency of the engine mount (approximately 5 to 15 Hz), which are the result, for example, of road excitations. By means of the process according to the invention for generating interference pulses, the arising of stuttering vibrations can be effectively counteracted.
For a period of detuning of the engine mount which is coupled to the rotational speed of the engine, sensors are provided on the drive assembly (engine and/or transmission) and sensors are provided on the body of the motor vehicle, which detect the acceleration values of the respective components. By means of the evaluation of the acceleration signals, stuttering movements of the drive assembly are detected and optionally a corresponding algorithm is started which detunes the assembly mount or mounts. In this case, the detuning preferably takes place periodically as a function of the rotational speed of the drive assembly (for example, coupled to the rotation of the crankshaft of the internal-combustion engine). However, in addition, a stochastic detuning can also be carried out.
Also, the process according to the invention can be used in an “anticipating” manner in that, during corresponding operating conditions of the vehicle, which lead to the expectation of the arising of stuttering vibrations with a certain probability, the assembly mounts are prophylactically detuned in a pulse-type manner.
The process last described by means of the drive assembly of a motor vehicle, can naturally also be used for other applications.
REFERENCES:
patent: 3483951 (1969-12-01), Bonesho et al.
patent: 4852245 (1989-08-01), Denk
patent: 4921272 (1990-05-01), Ivers
patent: 5145024 (1992-09-01), Doi
patent: 5628499 (1997-05-01), Ikeda et al.
patent: 5944297 (1999-08-01), Flower et al.
patent: 3910447A1 (1989-10-01), None
patent: 3932064A1 (1990-04-01), None
patent: 4021039 (1992-01-01), None
patent: 4120099A1 (1992-01-01), None
patent: 4123254A1 (1993-01-01), None
patent: 4233212A1 (1994-04-01), None
patent: 88111681 (1989-01-01), None
patent: 93103332 (1993-09-01), None
patent: 2660386 (1991-10-01), None
Flechtner Horst
Heltmann Hans
Horne William Mark
Kafer Thomas
Löschner Steffen
Bayerische Motoren Werke Aktiengesellschaft
Crowell & Moring LLP
Rodriguez Pam
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