Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-11-08
2003-01-07
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C318S114000
Reexamination Certificate
active
06504278
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an adjusting device for adjusting the resultant static moment of unbalanced-mass vibrators for the generation of directed oscillations, said static moment being generated by at least two pairs of unbalanced-mass part-bodies adjustable relative to one another over a relative adjustment angle &bgr;. A particular generic type of adjusting devices for unbalanced-mass vibrators for the generation of directed oscillations is described in the document EP 0 506 722 B1 to be included in the general prior art. For the sake of simplification, the terms used in said publication, namely the unbalanced-mass part-bodies and the centrifugal part-forces (or centrifugal part-force vectors), assigned to them, the unbalanced-mass part-bodies of one type and the other and the “pair” of unbalanced-mass part-bodies, have been adopted in the subsequent description of the present invention. In accordance with the publication mentioned, the relative adjustment angle &bgr; (subsequently called phase angle &bgr;) is also defined below in such a way that the value &bgr;=180° corresponds to a zero amplitude of oscillation and the value &bgr;=0° corresponds to a maximum amplitude of oscillation.
The phase angle &bgr; is theoretically defined between the centrifugal part-force vectors of the individual unbalanced-mass part-bodies of one type and the other of a “pair” of unbalanced-mass part-bodies. In practice, the phase angle &bgr; may also be defined between features (for example, geometric features) of the unbalanced-mass part-bodies of a pair, insofar as the position of the mass center of gravity of the eccentric mass is known. The identification “MR” is used for the reaction torques “MR” which, in the case of a phase angle &bgr;≠180°, occur twice as alternating moments during each unbalanced-mass revolution through the angle of rotation &mgr;=
2
&pgr; on the shafts of the unbalanced-mass part-bodies [these alternating moments have a sinusoidal profile with two minimum and two maximum values per revolution of the unbalanced-mass part-body].
The average reaction torques which act in only one direction and which can be calculated by integrating MR(&mgr;) against the angle of rotation &mgr;=2&pgr; and by subsequently dividing the integration value by 2&pgr; are designated here by “MRQ”. As a person skilled in the art may gather, for example, from the document EP 0 506 722 B1, in the case of a set phase angle 0°<&bgr;<180°, these average reaction torques MRQ [which themselves then represent a function of the phase angle &bgr;, hence: MRQ(&bgr;)] act on the unbalanced-mass part-bodies of a pair in such a way that the reaction torques MRQ of one type seek to accelerate the rotation of the unbalanced-mass part-bodies of one type and that the reaction torques MRQ of the other type seek to decelerate the rotation of the unbalanced-mass part-bodies of the other type. In an unbalanced-mass vibrator according to
FIG. 1
of the description of the invention, the result of this mode of operation, insofar as said vibrator were to operate in idling mode with a phase angle of, for example, &bgr;=90°, would be that the motor M
2
would have to operate in a motive way and the motor M
1
in a generative way, both motors (taking into account the output due to bearing friction) converting part of their power as apparent power. The operation of vibrator motors working with apparent powers is also clearly illustrated in
FIG. 2
of the document WO 97/19765 likewise included in the general prior art (it should be noted that this has a different definition of the phase angle &bgr; such that, here, &bgr;=0° is equated to an amplitude of oscillation=zero). It is pointed out at this juncture that a person skilled in the art is also aware of other designations, such as, for example, “centrifugal moment” or “unbalance moment”, for the designation “static moment”.
Furthermore, the present invention relates, in particular, to that generic type of piledriving vibrators which are adjustable in terms of their static moment and operate at high working rotary frequencies and which are designed for a particular operating mode such that, when they are used for work, the excitation of resonant frequencies f
R
lying below the working rotary frequency f
o
of the vibrator is to be avoided. In the directional vibrators which come under consideration for this operating mode, it is possible, by means of their control devices, during the rotation of the vibrator (in addition to the setting of any desired resultant static moments) to set selectively two particular resultant static moments: the setting of a “minimum position” with a minimum resultant static moment for the generation of an amplitude of oscillation equal to zero and the setting of a “maximum position” with a maximum resultant static moment for the generation of a maximum amplitude of oscillation. The particular operating mode works as follows: adjustment of the phase angle to the minimum position when the vibrator is at a standstill. Running up of the vibrator in the set minimum position to the working rotary frequency f
o
. Adjustment of the phase angle to the maximum position and execution of the vibration work. Adjustment of the phase angle to the minimum position. Reduction of the rotary frequency of the vibrator from the working rotary frequency to zero, with the minimum position being maintained. The particular operating mode last described is also to be referred to below by the designation “resonance avoidance operating mode”.
Two generic types of adjustable vibrators are known for executing an operating mode such as that described above. One generic type, which is described, for example, in EP 0 473 449 B1 or in EP 524 056 B1, works, for the purpose of adjusting the phase angle, with a mechanical variable-ratio gear unit, by means of which there is always a torque-transmitting connection of the unbalanced-mass part-bodies of one type to the unbalanced-mass part-bodies of the other type via the variable-ratio gear unit. In the other generic type of “motively adjustable vibrators”, the adjustment of the phase angle is brought about without a variable-ratio gear unit, specifically using adjusting motors which may at the same time also be working motors. The present invention is to be attributed to the last-mentioned generic type, since, in it, the adjustment of the phase angle is carried out, with drive motors also being included.
Insofar as the motively adjustable vibrators are intended, with the aid of a closed control loop and an angle measuring device, to make it possible to set and hold the phase angle continuously at any predeterminable value between &bgr;=180° and &bgr;=0° (as is provided, for example, in the case of EP 515 305 B1, EP 0 506 722 B1 and WO 97/19765), they are indeed suitable for executing the “resonance avoidance operating mode”, but they have the disadvantage that they are highly cost-intensive and that, in practice, it is not yet possible in a satisfactory way to regulate the phase angle in the range of about −90°<&bgr;<+90°. This is connected with the profile of the function of the reaction torque MRQ(&bgr;) or of the dependent necessary motor torque MD(&bgr;) in dependence bn the phase angle &bgr; (with a positive curve gradient in an angular range of about 0°<&bgr;<90° and with a negative curve gradient in the angular range of about 90°<&bgr;<180°), as may be gathered, for example, from
FIG. 2
of WO 97/19765. Another disadvantage is that, when the continuous regulation of the phase angle &bgr; is used even when the intention is to work only in the maximum position (point E or E′ in
FIG. 2
of WO 97/19765), during the run through the entire range of adjustment of the phase angle &bgr; the motors have to be loaded with far higher torques than is necessary for the maximum position.
If two further solutions are considered, which are disclosed by DE 44 39 170 A1 and WO 94/01225 a
Bald Hubert
Ludwig Brigitte
Alix Yale & Ristas, LLP
Gedib Ingenieurburo und Innovationsberatung GmbH
Nguyen Tran
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