Arrangement for continuously compensating for unbalance on a rotary member

An arrangement for continuously compensating for unbalance of a rotary member such as a grinding wheel comprises an annular container which is adapted to be coaxially secured to the rotary member to be balanced. The container is subdivided in its circumferential direction into a plurality of balancing chambers which are accordingly disposed at different angular positions in relation to the rotary member. A compensating liquid can be introduced into the respective balancing chambers from the exterior thereof to provide an unbalance compensating effect. Associated with each of the balancing chambers is a respective chamber emptying valve which for the purpose of emptying compensating liquid from the respective chamber can be actuated by an actuating piston arranged coaxially with respect to the container and axially displaceable by a drive controlled from the exterior of the arrangement. The actuating piston actuates valve displacement elements which are radially displaceable for opening and closing the chamber emptying valves, by the axial displacement of the actuating piston.

BACKGROUND OF THE INVENTION 
To provide for continuous compensation for unbalance of a rotary member 
such as a grinding wheel, for example during on-going operation thereof, 
it is possible to provide an arrangement comprising an annular container 
which is coaxially fixed to the rotary member to be balanced. The annular 
container is subdivided in its circumferential direction into a plurality 
of balancing chambers at different angular positions, into which a 
compensating medium such as a fluid can be selectively introduced from the 
exterior of the annular container, to provide for compensation in respect 
of unbalance of the rotary member. However, in operation of such an 
arrangement on a rotary member such as a balancing wheel, more an more 
compensating fluid is introduced into the balancing chambers for each 
respective unbalance compensating operation which has to be carried out, 
so that the balancing chambers become progressively filled to such an 
extent that it is ultimately no longer possible to provide an unbalance 
compensating effect. In that case the balancing chambers have to be 
emptied again. Provided for that purpose are chamber emptying valves which 
are operatively associated with the respective balancing chambers. The 
chamber emptying valves are actuated by an actuating member in the form of 
an annular deflector plate which acts on and thus actuates the respective 
chamber emptying valves by way of spring-loaded, axially disposed valve 
displacement elements which are in the form of push rod members. The 
deflector plate is actuated by nozzles which are disposed in directly 
opposite relationship to the plate, in an annular duct, and through which 
a pressure fluid can be directed on to the plate. In order to produce 
simultaneous displacement of the plate over the entire circumference 
thereof, that arrangement requires a comparatively large number of nozzles 
for directing pressure fluid on to the plate around the circumferential 
extent thereof. In addition, to provide for transmission of the control 
movement of the plate to the valve members of the chamber emptying valves, 
besides the spring-loaded, axially displaceable push rod members acting as 
valve displacement members to operate the chamber emptying valves, that 
arrangement also has single-arm levers which are associated with 
respective ones of the chamber emptying valves and which are actuated by 
virtue of the axial movement of the push rod members. When the levers are 
pivoted, they displace the respective valve members of the chamber 
emptying valves which are in the form of non-return or check valves. 
Therefore, to provide for the simultaneous opening of all the chamber 
emptying valves, the assembly requires a relatively large number of 
individual components which means that the amount of work involved in 
final assembly of the system is high. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an arrangement for 
continuously compensating for unbalance of a rotary member such as a 
grinding wheel, which is of a substantially simple construction while 
being reliable in operation. 
Another object of the present invention is to provide an arrangement for 
continuously compensating for unbalance of a rotary member, which provides 
for unbalance compensation by the introduction of a fluid into balancing 
chambers and wherein the balancing chambers can be readily emptied of 
fluid by a single actuating operation. 
Still another object of the present invention is to provide an arrangement 
for continuously compensating for unbalance of a grinding wheel by the 
introduction of a balancing fluid into a plurality of balancing chambers, 
wherein the balancing chambers can be emptied by actuation of chamber 
emptying valves in a single operation by means of a simple and reliable 
mechanism. 
In accordance with the principles of the present invention, these and other 
objects are achieved by an arrangement for continuously compensating for 
unbalance of a rotary member such as a grinding wheel, comprising an 
annular container adapted to be secured to the rotary member to be 
balanced in coaxial relationship therewith. The container is subdivided in 
its circumferential direction into a plurality of balancing chambers which 
are thus disposed at different angular positions in relation to the 
grinding wheel. A compensating medium which is capable of flow, such as a 
liquid, can be introduced into the balancing chambers from the outside of 
the container to provide for an unbalance compensating operation. 
Operatively associated with each of the balancing chambers are respective 
chamber emptying valves which are arranged outside the axis of rotation of 
the rotary member and therewith the container and which are closed in 
normal operation. When the balancing chambers are filled with balancing 
fluid, the chamber emptying valves can be opened from the outside of the 
arrangement by an actuating means by way of valve displacement members 
which engage the respective valve members of the chamber emptying valves, 
to provide for emptying of the associated balancing chambers. The 
actuating means comprises an actuating piston which is disposed in coaxial 
relationship with the annular container and which is axially displaceable 
by a drive means which is controlled from the outside of the arrangement. 
The axial displacement of the actuating piston causes radial displacement 
of the valve displacement elements to provide for opening and closing of 
the chamber emptying valves. 
As will be seen in greater detail hereinafter therefore the present 
invention uses an actuating means which is disposed concentrically with 
respect to the rotary member to be balanced and the annular container 
secured thereto and which acts on the valve displacement elements to move 
them radially to actuate the chamber emptying valves. The valve 
displacement elements thus extend generally in a radial direction from the 
actuating means to the respective chamber emptying valves. That design 
configuration not only provides a compact arrangement but it also gives a 
reduction in the number of individual components used as the actuating 
piston forming part of the actuating means is so designed that it moves 
the valve displacement elements in a radial direction. The valve members 
of the chamber emptying valves, which are operated by the valve 
displacement elements, are preferably also moved in a radial direction for 
opening and closing the respective valves. 
In a preferred feature of the invention, to provide for the radial movement 
of the valve displacement elements which are preferably in the form of 
simple elongate members such as pins or rods, the actuating piston has 
engagement surfaces which extend inclinedly relative to the axial 
direction of the arrangement and thus the axis of rotation of the rotary 
member and the container. The engagement surfaces on the actuating piston 
are in sliding engagement with the valve displacement elements to provide 
for radial displacement thereof. 
Preferably the valve displacement elements may have suitably adapted 
sliding surfaces which are in sliding engagement with the engagement 
surfaces of the actuating piston. 
Depending on the position of the actuating piston, the valve displacement 
elements are displaced radially outwardly or radially inwardly, and the 
associated chamber emptying valve can thus be opened or closed, in 
dependence on the respective positions of the valve displacement elements. 
Preferably, each valve displacement element may be provided with first and 
second sliding surfaces which are engaged by first and second inclined 
engagement surfaces of the actuating piston. The sliding surfaces of the 
respective valve displacement elements and the engagement surfaces of the 
actuating piston preferably extend parallel and are disposed on respective 
sides of a respective valve displacement element in the above-indicated 
inclined arrangement relative to the axial direction or the axis of 
rotation of the arrangement. 
In another embodiment of the invention the elongate valve displacement 
members may be disposed in guides of a simple configuration in a part of 
the body of the annular container, more especially in a wall of the 
container, and preferably in the ribs or partition walls between the 
respective chambers of the container. The valve displacement elements may 
thus to radially displaceably arranged in bores extending in the radial 
direction in the body of the container; when the valve displacement 
elements are in the form of circular rods or pins, the bores may be simple 
cylindrical bores in the body of the container. 
Preferably, in an arrangement in which the chamber emptying valves have 
valve members which are displaceable in a radial direction, the radially 
outer ends of the valve displacement elements may themselves be in the 
form of valve members which can be moved into the closed position and the 
opened position of the respective valve, by virtue of the actuating effect 
of the actuating piston. 
In a preferred embodiment of the invention, displacement of the actuating 
piston and therewith also the valve members of the chamber emptying valves 
is effected in particular when opening the valves against a return force 
which can be provided by means of one or more return springs which may 
engage the actuating piston and/or the respective valve displacement 
elements and/or the valve members of the respective valves. The return 
springs produce a return force urging the respective chamber emptying 
valves towards the closed position. 
In a preferred embodiment the actuating piston may have two forms of 
engagement surfaces which are inclined with respect to the axis of 
rotation of the arrangement and which are in operative engagement with the 
valve displacement elements of the respective valves. In that arrangement, 
the first engagement surface or surfaces are operative in the direction of 
opening of the respective chamber emptying valves and are preferably 
directed towards the axis of rotation of the arrangement while the other 
engagement surface or surfaces are directed away from the axis of rotation 
of the arrangement and are thus operative in the direction of closing of 
the chamber emptying valves. 
The compensating medium used is preferably a compensating liquid, in 
particular water. The compensating medium may be supplied to the annular 
chamber for an unbalance compensating effect both from the inward side of 
the annular container, as for example in German laid-open application 
(DE-OS) No. 35 35 717, and also from the face of the annular container as 
for example in German laid-open application (DE-OS) No. 23 57 629. 
Further objects, features and advantages of the present invention will be 
apparent from the following description of preferred embodiments thereof.

DESCRIPTION OF PREFERRED EMBODIMENTS 
In the following description and in the accompanying drawings comprising 
FIGS. 1 and 2 referring thereto, components which produce the same effect 
or have the same action and which are used in both of the illustrated 
embodiments are accordingly denoted by the same references. 
Referring firstly to FIGS. 1 and 2 in combination, the unbalance 
compensating arrangement illustrated in each of FIGS. 1 and 2 to provide 
for continuous compensation for unbalance of a rotary member (not shown) 
which may be for example a grinding wheel comprises a generally annular 
container 1 which can be suitably secured to the rotary member to be 
balanced in coaxial relationship therewith, for example by means of a 
flange mounting. In its interior the annular container 1 has a plurality 
of balancing chambers 24 which are arranged at different angular positions 
in the circumferential direction of the annular container 1 and thus also 
the arrangement of the invention and the rotary member to which it is 
secured in use thereof. To carry out an unbalance compensating operation, 
a compensating medium which is capable of flow, more especially for 
example water, is fed to the balancing chambers 24. The arrangement may 
have for example four or even more balancing chambers 24. 
In both of the embodiments shown in FIGS. 1 and 2, the compensating medium 
is supplied to the chambers 24 in the container 1 from the inward side of 
the container 1 by way of a suitable feed means indicated generally at 18 
in FIGS. 1 and 2. The feed means 18 has liquid feed ducts or passages 
which are formed in a mounting block 19. As can be seen from FIG. 1, the 
passages comprise a portion extending parallel to the axis of rotation A 
which is common to the annular container 1 and the rotary member to be 
balanced, a second portion which extends at an inclined angle to the axis 
of rotation A in an outward direction away from same and a third portion 
which then extends normal to the axis of rotation A and which is directed 
into circumferentially extending grooves 25 provided at the radially 
inward side of the annular container 1. In FIG. 2 the ducts or passages 
comprise a first portion extending parallel to the axis of rotation A and 
a second portion extending normal thereto, into the grooves 25. 
The grooves 25 in both FIGS. 1 and 2 have openings 26 which are 
communicated with the respectively associated balancing chambers 24 by way 
of communicating ducts 27 and valves 28 which in particular can be in the 
form of non-return or check valves. The openings 26, the communicating 
ducts 27 and the valves 28 which are associated with respective ones of 
the balancing chambers 24 are disposed in different angular positions 
distributed around the circumference of the annular container 1. In the 
embodiment illustrated in FIG. 1 the circumferentially extending grooves 
25, the openings 26 and the communicating ducts 27 are arranged in the 
inner annular portion of the annular container 1 while in the embodiment 
shown in FIG. 2 the above-indicated components together with the valves 28 
are disposed in an end or face portion of the body 12 of the annular 
container 1. 
In the embodiment shown in FIG. 1, the mounting block 19 in which, as will 
be described hereinafter, a drive means 6 and an actuating piston 2 are 
mounted, is fitted into the interior of the annular configuration of the 
container 1. The mounting block 19 is fitted in the annular container 1 by 
means of rolling bearing assemblies as diagrammatically indicated at 29. 
The annular container 1 is thus mounted rotatably relative to the block 19 
by means of the rolling bearing assemblies 29. 
In the embodiment shown in FIG. 2 the mounting block 19 is fixed to an 
outer cover portion 30 of the arrangement and projects into the central 
space in the end portion of the body 12 of the container. In this 
embodiment also the block 19 accommodates a drive means 6 for an actuating 
piston 2, but in the FIG. 2 embodiment the actuating piston 2 is mounted 
displaceably outside the mounting block 19 in the body 12 of the annular 
container 1, as will be described in greater detail hereinafter. 
Operatively associated with each of the balancing chambers 24 is a 
respective chamber emptying valve 4 which is closed in normal operation 
involving a balancing effect. In the lower part of FIG. 1, the chamber 
emptying valve 4 is shown in a closed position while in the upper part of 
FIG. 1 the chamber emptying valve 4 is illustrated in the open position. 
Conversely, the lower part of FIG. 2 shows the chamber emptying valve 4 in 
the open position while the upper part of FIG. 2 shows the chamber 
emptying valve 4 in the closed position. 
In both the illustrated embodiments, the radially outward ends of valve 
displacement elements 3 which extend in a generally radial array and which 
are of a rod-like or pin-like configuration form respective valve members 
9. The valve members 9 are formed by the radially outward ends of the 
respective valve displacement elements 3 being enlarged in diameter to 
form a disc-like configuration, and carry a valve seat material as 
indicated at 31 at their respective radially outwardly facing face. For 
actuation of the valve displacement elements 3, that is to say to move the 
valve displacement elements 3 in a radial direction, the arrangement 
includes an actuating means comprising an actuating piston 2 which is 
disposed in coaxial relationship with the annular container 1. Formed on 
the actuating piston 2 are engagement fingers 13 which are disposed in 
spaced relationship around the periphery of the piston 2 and which have 
engagement surfaces 5 and 22 at respective sides thereof. Each two 
engagement fingers 13 are in operative engagement with a respective 
radially inwardly disposed end portion of the associated valve 
displacement element 3. The engagement surfaces 5 and 22 on the engagement 
fingers 13 carried by the actuating piston 2 extend inclinedly relative to 
the axis of rotation A. The engagement surfaces 5 are directed towards the 
axis of rotation A, that is to say they are disposed on the radially 
inwardly facing sides of the respective fingers 13, while the engagement 
surfaces 22 are directed away from the axis of rotation A and are thus 
disposed on the radially outwardly facing surfaces of the respective 
fingers 13. 
Each side of each valve displacement element 3 has a respective groove 
which is provided in the radially inwardly disposed end portion of the 
valve displacement element 3. The grooves extend inclinedly with respect 
to the axis of rotation A and the engagement fingers 13 engage into 
respective ones of the grooves. The engagement grooves are defined by 
sliding surfaces as indicated at 7 and 23 in FIGS. 1 and 2, the sliding 
surfaces 7 and 23 also extending inclinedly with respect to the axis of 
rotation A. More specifically, the sliding surfaces 7 and 23 on the valve 
displacement elements 3 extend inclinedly relative to the axis of rotation 
A at the same angle as the engagement surfaces 5 and 23 on the actuating 
piston 2. Of the engagement surfaces 5 and 23, at least the respective 
surfaces 5 which face towards the axis of rotation A can come into 
engagement with the associated sliding surfaces 7 on respective ones of 
the valve displacement elements 3, more particularly when the valve 
displacement elements 3 and therewith the valve members 9 carried or 
formed thereon are moved radially towards the axis of rotation A. 
As mentioned above, the arrangement in accordance with the present 
invention has an actuating means comprising an actuating piston 2 and a 
drive means 6 for actuation of the valve displacement elements 3 and the 
respective valve members 9. In the embodiment illustrated in FIG. 1 the 
actuating means is disposed in the mounting block 19. To provide for the 
drive for the actuating piston 2 against a return force produced by return 
springs 14 and 15, the drive means 6 has a working piston 8 which is 
axially slidably mounted in the mounting block 19. A pressure fluid can be 
introduced into a working chamber 32 which is disposed to the right of the 
working piston 8 in FIG. 1, by way of a hydraulic conduit 33, so that the 
working piston 8 and therewith the actuating piston 2 are displaced 
towards the left in FIG. 1, from the normal position towards the right in 
FIG. 1, as illustrated in the lower half of FIG. 1, inwardly towards the 
rotary member to be balanced, against the force of the return spring 14 
which acts on the actuating piston 2, and also against the force of the 
respective return springs 15 which act on the valve members 9 to urge them 
radially outwardly. As a result of that actuation, the actuating piston 2 
takes up the position towards the left as shown in FIG. 1 above the axis 
of rotation A, in which case the engagement surfaces 5 which face towards 
the axis of rotation A come into sliding engagement with the engagement 
surfaces 7 of the valve displacement elements 3. In that situation, by 
virtue of the inclined arrangement of the engagement surfaces 5 and the 
sliding surfaces 7 relative to the direction of displacement of the 
actuating piston 2, the valve displacement elements 3 and therewith the 
respective valve members 9 of the chamber emptying valves 4 are drawn 
radially inwardly towards the axis of rotation A into the opened position 
of the valves, as illustrated in the upper half of FIG. 1. In that 
position the balancing chambers 24 can be emptied of fluid therein, by 
rotating the arrangement. The centrifugal force which is produced in that 
situation causes the compensating liquid which is contained in the 
balancing chambers 24 to escape through the normally closed discharge 
passage 34 operatively associated with each chamber emptying valve 4. 
After conclusion of the emptying operation, the pressure fluid is 
discharged from the working chamber 32 at the right of the working piston 
8 in FIG. 1 through the hydraulic conduit 33 so that the working piston 8 
and therewith the actuating piston 2 are displaced axially towards the 
right in FIG. 1 into the position shown in the lower half of FIG. 1. That 
movement is assisted and promoted by the return force of the return spring 
14, and the radially outwardly directed movement of the valve displacement 
elements 3 and the valve members 9 into the closed position of the chamber 
emptying valves 4 as shown in the lower half of FIG. 1, such movement 
being produced by the movement of the actuating piston 2, is assisted by 
the respective return springs 15 which act on the valve members 9. As in 
the embodiment illustrated in FIG. 1 the outwardly directed engagement 
surfaces 22 on the actuating piston 2 come into engagement with the 
associated sliding surfaces 23 on the valve displacement elements 3, the 
radially outwardly directed movement of the valve displacement elements 3 
is produced by the co-operation of the engagement surfaces 22 and the 
sliding surfaces 23. The function of the return springs 15 is primarily to 
compensate for any mechanical clearances between the individual components 
of the assembly and to apply a well-defined static force to the chamber 
emptying valves. In the closed position the discharge passages 34 
associated with the respective chamber emptying valve 9 are then closed so 
that no compensating liquid can then escape from the balancing chambers 
24. 
In order for the rod-like or pin-like valve displacement elements 3 in FIG. 
1 to be satisfactorily guided, the body 12 of the container 1 has radially 
extending bores acting as guides as indicated at 11 for the valve 
displacement elements 3 which are thus radially slidably guided therein. 
To provide for satisfactory guidance of the valve members 9, suitably 
shaped valve housing 10 are disposed in the body 12 of the annular 
container 1. In the FIG. 1 embodiment the valve displacement elements 3 
and the chamber emptying valves 4 are disposed in the wall portion of the 
annular container 1 which is towards the rotary member to be balanced (not 
shown), and are preferably provided in the rib portions or partitions 
between the chambers 24 of the annular container 1. 
In normal operation, that is to say when the rotary member to be balanced 
is rotating, the annular container 1 also rotates therewith and any 
unbalance which occurs at the rotary member in that phase of operation is 
detected by means of an unbalance measuring device (not shown), and a 
control arrangement (not shown) is then actuated in dependence on the 
unbalance measurement result. The control arrangement provides that 
suitable amounts of compensating liquid corresponding to the unbalance 
detected are supplied by way of the feed conduits of the feed means 18 
into the appropriate balancing chambers 24. During that phase of 
operation, the respective valves 28 which can be in the form of check 
valves which are opened by centrifugal force are in fact opened so that 
the respective required amount of compensating liquid can be passed to the 
corresponding balancing chamber or chambers 24. When operation of the 
arrangement and the rotary member to be balanced is stopped, the valves 28 
close, due to the absence of centrifugal force for actuating same, thus 
providing a closed circuit so that the balanced condition is retained for 
re-commencing operation of the system. 
When the balancing chambers 24 are filled with compensating fluid, the 
above-described emptying operation has to be carried out. 
As, while the system is in operation, that is to say while the annular 
container 1 of the arrangement according to the invention is rotating, the 
actuating piston 2 must also rotate with the valve displacement elements 
3, the actuating piston 2 of the embodiment shown in FIG. 1 is mounted by 
way of rolling bearing assemblies 35 in the working piston 8 which is of a 
cup-like configuration. That design provides that the actuating piston 2 
can rotate relative to the working piston 8 and the mounting block 19 
which does not rotate. As already mentioned, the annular container 1 is 
supported rotatably relative to the block 19, at its inward annular 
portion, by way of the rolling bearing assemblies 29. 
In the embodiment shown in FIG. 2, the closed position of the chamber 
emptying valves 4 is illustrated in the upper half of FIG. 2 while the 
open position of the chamber emptying valves 4 is illustrated in the lower 
half of FIG. 2. The mode of operation of the FIG. 2 embodiment is in 
substance the same as that of the embodiment shown in FIG. 1. In the FIG. 
2 construction however the actuating piston 2 is mounted in the inner 
annular portion of the annular container 1. The drive means 6 comprises a 
piston rod 17 which can be automatically or manually actuated from the 
exterior of the arrangement and which can be displaced with a 
reciprocating motion along the axis of rotation A. the piston rod 17 is 
mounted in the mounting block 19 which is fixed to an outer cover means 30 
of the arrangement of the invention. The working piston 8 is mounted 
rotatably about the piston rod 17, by means of rolling bearing assemblies 
indicated at 36. The working piston 8 is reciprocated by actuation of the 
piston rod 17. 
In normal operation the piston rod 17 is in the left-hand position shown in 
the upper half of FIG. 2. In that position the chamber emptying valves 4 
are closed. When the annular container 1 rotates, together with the rotary 
member to be balanced, the effect of centrifugal force means that the 
valves 28 open so that if necessary, when unbalance occurs on the rotary 
member to be balanced, compensating liquid can be supplied to the 
appropriate balancing chambers 24. The compensating liquid is supplied by 
way of feed conduits of the feed means 18 which are directed into the 
respective annular grooves 25, and by way of the corresponding openings in 
the annular grooves 25 and by way of the valves 28 which are opened by the 
effect of centrifugal force, to the respective balancing chambers 24. 
When the balancing chambers 24 are filled so that it is no longer possible 
to compensate for any further unbalance, the piston rod 17 is moved in the 
axial direction towards the right in FIG. 2, towards the rotary member to 
be balanced. With that movement, the working piston 8 is also move towards 
the right and urges the actuating piston 2 which is axially slidable in an 
inner annular portion 20 of the annular container 1, against the return 
force of a return spring 16, into the right-hand position shown in the 
lower half of FIG. 2. In that movement, the engagement surfaces 5 which 
are provided on the actuating piston 2 or more specifically on the 
engagement fingers 13 thereof and which extend inclinedly with respect to 
the axis of rotation A come into engagement with the corresponding sliding 
surfaces 7 on the valve displacement elements 3. As a result of such 
engagement, the valve displacement elements 3 and the valve members 9 
connected thereto are drawn radially inwardly towards the axis of rotation 
A. As a result, the chamber emptying valves 4 are opened, as shown in the 
lower half of FIG. 2. The compensating liquid in the balancing chambers 24 
can then be discharged therefrom through the discharge passages 34 due to 
the effect of centrifugal force when the annular container 1 is rotated. 
After the operation of emptying the balancing chambers 24 has been 
concluded, the piston rod 17 is moved towards the left again and the 
return force of the return springs 16 also causes the actuating piston 2 
to be moved into its left-hand position as shown in the upper half of FIG. 
2. When that happens the chamber emptying valves 4 are closed again. When 
that closing movement takes place, the inclined engagement surfaces 22 on 
the actuating piston 2, which face radially outwardly away from the axis 
of rotation A, are pressed against the sliding surfaces 23 on the valve 
displacement elements 3, which are inclined in the same manner, so that 
the valve members 9 are moved into their closed positions, due to the 
return force of the return springs 16 acting on the actuating piston 2. As 
in the embodiment shown in FIG. 1, the FIG. 2 arrangement may also have 
return springs which act on the respective valve members 9 and which urge 
them towards their closed position. 
It will be appreciated that the above-described embodiments in accordance 
with the present invention have been set forth solely by way of example 
and illustration of the principles of the invention and that various 
modifications and alterations may be made therein without thereby 
departing from the spirit and scope of the invention.