Damping device for machine sets having a vertical rotor shaft

A device for damping vibrations in machine sets having a vertical rotor shaft including an annular cushioning element and springs resiliently supporting the cushioning element on the machine set. The springs may include vertically acting springs and horizontally acting springs which may be equally circumferentially distributed and adjustable.

The present invention relates generally to damping mechanisms and more 
particularly to a device for damping vibrations in machine sets having a 
vertical rotor shaft. 
Machines of the type to which the present invention relates having a 
vertical rotor shaft may, for example, be vertical cooling water pumps or 
similar machines. In such devices, evaluation or calculation of vibration 
characteristics before assembly of the machine derived from instrument 
readings is frequently impossible or would otherwise require an 
unreasonable expediture. In the literature, for example "Mechanische 
Schwingungen" by J. P. Den Hartog, published 1952 by Springer Verlag, or 
VDW-Konstrukteur-Arbeitstagung, January 1969, WZL page 288 f.f., which 
relate to theoretical considerations, there are provided tentative 
solutions for vibration systems. However, these publications do not 
contain teachings which will enable one of ordinary skill in the art to 
cope with the complex vibration phenomena which occur in machine sets of 
the type referred to above. 
The present invention is directed toward the provision of a solution 
enabling damping within permissible values of the vibration amplitudes in 
vertical machinery while permitting the installation of damping facilities 
after assembly of the machines. Furthermore, the invention enables 
machines which are already in plant service to be re-equipped with such 
facilities by relatively simple means. 
SUMMARY OF THE INVENTION 
Briefly, the present invention may be described as a damping mechanism of 
the type previously discussd which comprises an annular cushioning mass 
which is resiliently supported on the machine to provide the desired 
damping characteristics. 
By a more specific aspect of the invention, the annular cushioning mass may 
be joined about the circumference of a machine housing by a first set of 
spring elements which will provide a vertically directed resilient damping 
force between the machine and the annular cushioning element and by a 
second set of spring elements which provide horizontally directed damping 
spring forces between the annular cushioning element and the machine 
housing. 
The invention provides a particular advantage in that only a single 
cushioning element is required for vibration damping. The resilient 
suspension system and the annular design of the cushioning element combine 
to provide three degrees of freedom of movement for the cushioning element 
whereby the cushioning element is movable in a horizontal and in a 
vertical direction as well as about a vertical centerline. Thus, the 
cushioning element will be free to move in vibration planes not previously 
definable and it may be adapted to various planes of vibration while the 
machine is operating. 
In accordance with a more specific feature of the invention, the annular 
cushioning element or mass is equipped with at least spring elements which 
are circumferentially equally spaced and which act in the horizontal 
direction and with at least three equally circumferentially spaced spring 
elements acting in the vertical direction. 
The provision of such elements makes it possible for the cushioning mass to 
move in different planes of vibration and to operate at the same time to 
transfer the necessary impulses for damping to the machine by simple 
means. Spring elements which are capable of use with the present invention 
may include all applicable resilient suspensions. These may consist of 
supports of flexible materials of construction, for example, rubber pads, 
or of plate springs, spiral springs, or similar elements. 
In a preferred embodiment of the invention, provision is made for the 
spring elements to be adjustably attached with the annular cushioning 
mass. This features permits tuning of the damping frequency of the device 
by simple means which will be effective even during operation of the 
machine. When the machine is stationary or not in use, the springs may be 
replaced by springs of different characteristics with subsequent 
adjustment in order to satisfy conditions which may be imposed by 
prevailing vibration behavior of the machine set. 
The invention also provides holding members firmly attached to the machine 
operating to support at least the vertically acting spring elements. These 
holding members may, for example, be in the form of angle brackets or an 
angle-iron ring surrounding the housing of the machine and affixed thereto 
by welding, bolting or other means. In the case of spring failure, the 
holding member will prevent the cushioning mass from dropping or moving, 
thereby avoiding damage to the machine. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its use, reference 
should be had to the accompanying drawing and descriptive matter in which 
there is illustrated and described a preferred embodiment of the invention 
.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawing, an assembly in accordance with the present 
invention is depicted wherein a machine set 2 is placed in a vertical 
position upon a horizontal plane 1. The machine set as shown consists of a 
motor 3 with a flanged coupling section 4 and a machine 5, which may for 
example be a cooling water pump. 
The upper part of the motor 3 is provided with a number of angle iron 
members 6 which are, for example, welded to the housing of the motor 3 and 
which serve as support or holding members for a series of vertical spring 
elements 7 arranged circumferentially spaced about the motor 3. An annular 
cushioning mass or element 8 is supported by the vertical spring elements 
7 which are interposed between the annular cushioning element 8 and the 
angle iron members 6. 
In addition to the first set of vertical spring elements 7, there is also 
provided a second or further set of spring elements 9 which are interposed 
between the annular cushioning mass 8 and the housing of the motor 3. The 
spring elements 9 act in a horizontal plane and provide a damping force in 
the horizontal direction between the annular cushioning mass 8 and the 
housing of the motor 3. Of course, the spring elements 9 may also be 
interposed between the cushioning element 8 and the angle iron members 6, 
if the members 6 are extended vertically beyond the location depicted in 
FIG. 2. 
The horizontal spring elements 9 are adjustable by means of, for example, 
threaded or screwed elements 10 which extend through the cushioning mass 
8. In the same manner, the spring elements 7 which are attached with the 
cushioning mass 8 may also be made adjustable by similar means, although 
this is not depicted in detail in the drawing. 
It will be apparent to those skilled in the art that various modifications 
may be effected in the embodiment described without deviating from the 
spirit and scope of the invention. For example, instead of utilizing four 
pairs of spring elements 7, 9 as shown in FIGS. 1 and 2, provision may be 
made for three pairs of spring elements equally circumferentially spaced 
about the housing of the motor 3. Instead of arranging the spring elements 
in pairs, the elements may be attached to the cushioning mass 8 in a 
staggered pattern. The cushioning mass 8 may be composed of segments or it 
may consist of a continuous annular member. Additionally, the cushioning 
mass 8 may be provided with facilities for accommodating balancing 
elements (not shown). The spring elements may be formed as spiral springs 
or as plate springs, depending upon the arrangement of the cushioning 
mass. They may be of flexible plastic material or they may be formed as 
rubber blocks or similar elements. The holding member 6 arranged beneath 
the cushioning mass 8 may also be located above the cushioning mass. The 
cushioning mass may then be suspended from such members and it may be 
provided with limit stops which will prevent the cushioning mass from 
dropping below a particular point in the case of spring failure thereby to 
avoid damage to the equipment. 
While a specific embodiment of the invention has been shown and described 
in detail to illustrate the application of the inventive principles, it 
will be understood that the invention may be embodied otherwise without 
departing from such principles.