US3783701A

US3783701A - Vibrator

Info

Publication number: US3783701A
Application number: US00279170A
Authority: US
Inventors: W Steprath; M Birkholz
Original assignee: Maschinenfabrik Buckau R Wolf AG
Current assignee: BWS Technologie GmbH
Priority date: 1971-08-10
Filing date: 1972-08-09
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: DE2140006B1; CA962093A; CH537218A; AT319996B; FR2149942A5; JPS4835467A; GB1368839A

Abstract

In an apparatus for producing vibrations, there is provided a combination consisting of a housing having an annular channel and at least one mass accomodated in and movable circumferentially of the channel. The combination further includes an arrangement for effecting movement of the mass circumferentially of the channel to respective locations therein. Abutments are provided in the channel for impeding movement of the mass through distances in excess of a predetermined portion of arc.

Description

United States Patent 1191 i Jan. 8, 1974 Steprath et al.

" VIBRATOR [75] Inventors: Werner Steprath, Gohr; Manfred Birkholz, Schoenkirchen, both of Germany [73] Assignee: Maschinenfabrilt Buckau R. Wolf Aktiengesellschaft, Grevenbroich, Germany [22] Filed: Aug. 9, 1972 21 Appl. NO.Z 279,170

301 Foreign Application Priority Data Aug. 10,1971 Germany P 21 40 006.6

52 Us. c1..;.....v 74/87, 259/1510.v 42 [51] 1m. 01. mama/10 58 Field of Search... 74/61,*87;

[56] References Cited UNITED STATES PATENTS 2,747,418 5/1956 Eckley 209/3665 X 2/1950 High 74/61 X 2,703,490 3/1955 Brueggeman et al. 74/61 X 2,793,009 5/1957 Peterson 74/61 X 2,829,527 4/1958 Fleming 74/61 4/1958 Ongaro 74/61 Primary ExaminerAllan D, Herrmann Att0rneyMichael S. Striker [57] I ABSTRACT In an apparatus for producing vibrations, there is provided a combination consisting of a housing having an annular channel and at least one mass accomodated in and movable circumferentially of the channel. The combination further includes an arrangement for effecting movement of the mass circumferentially of the channel to respective locations therein.v Abutments are provided in the channel for impeding movement of the mass through distances in excess of a predetermined portion of arc.

18 Claims, 3 Drawing Figures Vibrating rollers for smoothing and/or compacting of soil .or of street and other surfaces make use of the vibrators of the art. These vibratorsv are provided with one or more imbalanced weights or masses, which imbalance causes vibrations to be produced when the vibrator is in motion. The vibrator may be mounted on a shaft or other device which rotates continuously, thereby providing continuous vibrations. The energizing force, that is the force responsible for the vibrations, is the weight imbalance. Since the vibrations are continuous, depressions are formed in the surface during a change in the direction of travel of the roller. This is due to the fact that the vibrations are concentrated on one location for the time which is required to stop movement of the roller and to reverse its direction. Also, premature stoppage of the vibrator may impair the cohesiveness of the surface. It is irrevelant, in this regard, whether the roller has one or more rolling wheels and whether a vibrator is provided within each rolling wheel or only .within the driving roller wheel frame. It is to be noted that thesmaller the imbalance the smaller the energizing force and when no imbalance exists no energizing force exists.

The reversing action from forward to reverse motion of the roller requires only seconds and it is not possible to stopvthe vibratorwithin this time span. Thus, the

above disadvantages can only be overcome by cancelfrom German'Pat. No. 926,308. Here, the displacement of the mass causing the imbalance, and hence the adjustment of the energizing force, can be accomplished hydraulically during movement of the roller. In this case, however, only a single mass'is involved, for the displacement of which the hydraulic pressure must be constantly maintained. The displacement of the mass in a radial direction occurs in opposition to the pressure exerted by a spring such a construction is not usable in practical operation and, further, the energizingforce is not completely cancelled therein. It is further known (from DT-OS 1,634,474) that two masses rotating in opposite sense provide the greatest possible centrifugal moment within a circular cross section. The

imbalance, and hencethe energizing force, due to the masses may be cancelled by displacing the masses through opposing half-angles of the arc defined by a circular cross section. Both of the masses are displaced by hydraulic or pneumatic means. Here, friction bearings with high bearing friction are used and, as a result, the bearings are very expensive.

In addition, the expenditure required for the production of these various vibrators known from the art is i very high. Furthermore, due to the high bearing friction in the last-mentioned construction, complicated controls are necessary for displacement of the masses, which controls must also be used to obtain intermediate amounts of imbalance or energizing force.

The above disadvantages have not, until now, been overcome.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to overcome the above disadvantages.

More specifically, it is an object of the present invention to provide a vibrator which does not possess the above disadvantages.

It is, further, an object of the present invention to provide a vibrator wherein the energizing force can be readily cancelled for a requisite time, e.g. the time necessary to reverse the direction of motion of a compacting roller with which it is associated.

A further object of the present invention is to provide a vibrator wherein cancellation of the energizing force can occur while the roller with which it is associated,

is in motion.

It is yet another object of the present invention to provide a vibrator which is practical to use.

An additional object of the present invention is to provide a vibrator which is inexpensive to produce.

Yet a further object of the present invention is to provide a vibrator which does not require complicated controls.

Still one more object of the present invention is to provide a vibrator the operation of which will not result in damage or impairment of surfaces to be smoothed, compacted or otherwise finished with the aid of the vibrator. v v 7 Basically, then, the invention concerns itself with the problem of creating a continuously adjustable vibrator for apparatus utilizing vibrating rollers, vibrating plates or similar devices, wherein the energizing force resulting from the imbalance of angular offset masses, may be changed by the application of the lowest possible displacement forces. It is further desired to simultaneously make use of the restoring forces arising in operation of the novel apparatus.

Briefly stated, one feature of the invention resides in an apparatus for producing vibrations, having a combination comprising wall means defining an annular channel and at least one mass accommodated in and movable circumferentially of the channel. The combination further includes moving means for effecting movement of the mass circumferentially of the channel to respect locations therein. Abutment means are provided in the channel for impeding movement of the mass in excess of a predetermined portion of arc.

The invention thus pertains to a vibrator for use in vibrating apparatus utilizing vibrating plates, vibrating rollers or similar devices, wherein one or more movable masses are accommodated within an annular channel which is concentric with a shaft.

More particularly, the above-mentioned problem is solved, according to the present invention, by using masses of cylindrical form which are located in a rotationally symmetrical channel. The channel is provided with at least one abutment element for the cylindrical masses, and is connected to a source of pressure fluid so that such fluid can be admitted into the channel.

This vibrator operates as an overcritical revolving body and is designed to rotate about its principal inertial axis. With the help of the pressure fluid and, if nec essary, the abutment elements, the cylindrical masses are set at such relative angular positions within the annular channel that they provide the imbalance neces sary to produce the desired vibrations. If the flow of pressure fluid is interrupted, then, as a result of the inherent restoring forces, the cylindrical masses move circumferentially and almost friction-free, along the inner surface of the outer wall banding the annular channel. This movement continues until the principal inertial axis is again coincident with the axis of symmetry of the vibrator so that the vibrator is once more balanced, i.e., so that no more imbalance exists. It is thus possible, by simplest means, to cancel the energizing force in a fraction of a second.

With the mode of action presented by the invention, the displacement forces for the masses may be held to very low values and, in addition, the restoring forces inherently arising from the relative angular displacement of the masses are put to use.

A vibrator according to the invention can, for example, be used in a vibrating-plate compactor for an application where different varieties of surfaces are to be compacted or finished and where, accordingly, rapid displacement of the masses is necessary.

Another feature of the invention lies in a construction wherein the channel is formed from a pair of discs connected to and surrounding a shaft, and a circumferential wall accommodated between the discs and connected to their outer peripheries. In this manner, an annular channel or rectangular cross section is provided which, on technical production grounds, is simple to manufacture. Ideally, a channel of circular cross section with spherical masses accommodated therein, should be used. However, a channel of circular cross section is so much more expensive to produce that the technical advantages of using such a channel are not worth the cost.

The abutment elements in the channel may be in the form of bolts extending at least partly across the channel, or dividing walls. A particularly advantageous configuration provides for two abutment elements which are located diametrically opposite each other. In such a case, when two masses of equal weight are accommodated within the channel, no imbalance can be produced when the vibrator first begins to rotate. The reason for this is that each of the masses initially abuts against one of the abutment elements, thereby causing the two masses to be retained in positions diametrically opposite each other, with the result that the masses balance one another. I

A particularly simple construction is obtained if'one of two cylindrical masses is fastened in the channel by means of one of the abutment elements. The second element is then so mounted with the channel, i.e., diametrically opposite the first element, that the second cylindrical mass has a range of travel of 180 of arc circumferentially of the channel. This produces a rotation of the imbalance vector relative to the revolving vibrator during displacement of the mass.

Another feature of the invention lies in a construction wherein two dividing walls, each constituting an abutment and being located diametrically opposite one another, divide the channel into two portions each of which accommodates one cylindrical mass. In this case, the imbalance vector remains stationary relative to the revolving vibrator during displacement of the masses.

Although the channel will normally always be filled with pressure fluid, it is necessary, in order to displace the masses, to provide means for producing pressure within the channel. For this purpose, the shaft on which the channel is mounted is provided with an inlet and an outlet which communicate with the channel on the one hand and are connected to a source of pressure fluid on the other hand. In the case where one cylindrical mass is fastened in the channel and a second cylindrical mass has a range of travel of arc circumferentially of the channel, the inlet and outlet must communicate with the channel on opposite sides of the fastened mass, as seen in circumferential direction of the channel. Where two dividing walls divide the channel into two portions, both dividing walls are provided with at least one transverse passage, each of which communicates with the channel on both sides of the respective dividing wall. The inlet and outlet are then each connected to one of the respective transverse passages. A a result of this arrangement and the fact that the direction of flow of the pressure fluid is reversible, it is possible to control the flow of pressure fluid and, thereby, the angular positions of the masses relative to one another in the channel, by very simple means.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a vibrator according to the present invention, in a cross-sectional view;

FIG. 2 is an axial section of the embodiment illustrated in FIG. 1, and

FIG. 3 shows a further embodiment of the invention in a view similar to FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention may be best understood by referring to the attached drawing in conjunction with the following discussion. With regard first to FIG. 2, a shaft 1 is provided with a hub2. A pair of discs 3, 4 are connected to and surround the shaft 1 at the axial ends of the hub 2; together with a circumferential wall 5 and the hub 2 these discs 3 and 4 form an annular channel 6 having a rectangular cross section. The diameter of the discs 3, 4 is greater than that of the hub 2 and the circumferential wall 5 is fluid-tightly connected to the outer peripheries of the discs 3, 4.

Referring now to FIG. 1, it will be seen that the channel 6 accommodates two masses 7, 8 which are in the form of cylinders or rolls and whose length is slightly less than the dimension of the channel 6 in axial direction of the shaft 1. The mass 7 is fastened in the channel 6 by a diagrammatically illustrated bolt or analogous means 9a. The second mass 8 is free to move circumferentially of the channel 6. A bolt 9, fast with the cylindrical'hub 2 and extending at least partly across the channel 6, is so located that the mass 8 has a range of travel of 180 of arc circumferentially of the channel 6 between the bolt 9 and the fastened mass 7. Whenever the vibrator is at rest, the mass 8 will be located at the lowest point of channel 6.

I As soon as the vibrator is made to rotate in the direction of the arrow A, the bolt 9 abuts against the mass 8 thereby locating it diametrically opposite the fastened mass 7, as a result of which no imbalance and, hence, no energizing force exists. In order to now provide an imbalance and, hence, an energizing force, an inlet passage or bore 12 and an outlet passage or bore 13 are provided in the shaft 1 and hub 2. As can be seen from FIG. 2 the inlet bore 12 and outlet bore 13 are connected to a diagrammatically illustrated source of pressure fluid 18, for example by means of' the respective ducts 16,17. The source of pressure fluid 18 may be or may include a reversible pump; such pumps are known per se. With reference again to FIG. 1, when now, after the rotational operating speed of the vibrator has been attained, a stream of pressure fluid is pumped through the inlet bore 12 into the channel 6, the mass 8 moves away from the bolt 9 and towards the fastened mass 7, under the pressure of such fluid. This produces an imbalance and, hence, an energizing force. The vibrator has the greatest imbalance and, consequently, the largest possible energizing force, when the mass 8 lies adjacent the mass 7.

Since the apparatus containingthe vibrator may oscillate either freely or on the partly elastic surface upon which it is to act, the center of rotation of the vibrator may shift from the middle of the vibrator towards the position of the center of mass of the masses 7, 8.

As a result of the thus obtained eccentric rotation, the centrifugal forces of the mass 8 no longer act perpendicularly to the circumferential wall 5 and a restoring force arises which is due to the weight of the mass 8. When the hydraulic flow, i.e., the flow of pressure fluid, is shut off, the restoring force acts in such a manner that the mass 8 moves circumferentially away from the mass 7 and continues to move until it reaches a position in which the vibrator is again balanced. In other words, the mass 8 moves circumferentially of the channel 6 until the masses 7, 8 are again diametrically opposite each other and no imbalance exists. The restoring force is approximately proportional to the energizing force. Further, by controlling the rate of flow of the pressure fluid, it is possible to move the mass 8 to and maintain it in any desired position in channel 6. Thus, the hydraulic pressure is approximately proportional to the energizing force. The control range, that is, the range of pressure necessary to control the m0- tion of the mass 8, is of the order of magnitude of 0-2 atmospheres in excess of atmospheric pressure.

If the hydraulic flow through the inlet bore 12 is shut off, the mass 8 moves away the mass 7 until it abuts against the bolt 9 as mentioned before, thereby eliminating the imbalance. In view of the above-mentioned restoring force, this return movement of the mass 8 occurs in a fraction of a second; it can be further accelerated by reversing the flow of the pressure fluid (e.g. by reversing the operation of the reversible pump).

Referring next to FIG. 3 which shows another embodiment of the invention, it can be seen that here the channel 6 is divided into two portions or compartments 6a, 6b by means of the dividing walls l0, 11. Each portion 6a, 6b accommodates one of the movable cylindrical masses 7, 8. When the vibrator begins to rotate,

mentum. Since the dividing walls 10, 11 are located diametn'cally opposite each other, no imbalance exists. Here again, as in the illustrative example of FIG. 1, once the operating rotational speed of the vibrator has been attained, a stream of pressure fluid is made to flow through the inlet bore 12. The pressure fluid exists from the inlet bore 12 into the transverse passage 14 provided in the dividing wall 10. The transverse passage 14 communicates with the portions 6a, 6b at the respective opposite sides of the dividing wall 10. Thus, the pressure fluid may flow .into the portions 6a, 6b, thereby allowing the portions 6a, 6b to become filled with this fluid. A transverse passage 15 is further provided in the dividing wall 11. The transverse passage 15 also communicates with the portions 6a, 6b at the respective opposite sides of the dividing wall 11. Thus, the pressure fluid may flow from the portions 6a,'6b into the transverse passage 15. The pressure fluid exits from the transverse passage 15 into the outlet bore 13. The inlet bore 12 and the outlet bore 13 are connected to a source of pressure fluid 18 as shown in FIG. 2 and asexplained earlier. Again, the source of pressure fluid may include a reversible pump. Assume now, in FIG. 3, that when the vibrator begins to rotate, the dividing walls 11, 10 abut against the masses 7, 8, respectively. Then, the stream of pressure fluid through the transverse passage 14 displaces the mass 8 until it, also, abuts against the dividing wall 11 thereby producing the maximum imbalance. In this case also, as soon as the stream of pressure fluid is shut off, the masses 7, 8 move away from each other until they once again lie diametrically opposite one another, thus eliminating the imbalance.

Both of the

bores

12, 13 of FIGS. ll-3 may be connected to the same source of pressure fluid 18, as shown in FIG. 2. The source 18 may include, for example, reversible hydraulic or pneumatic means for conveying the pressure fluid from the source 18 into the

bores

12, 13. Thus, the direction of flow of the pressure fluid can be reversed. Referring again to FIG. .3 as an example, it is then possible to convey the pressure fluid into the portions 6a, 6b through either one of the

trans verse passages

14, 15 and to let it exit from the portions 6a, 6b through either one of the

transverse passages

15, 14. As a consequence, the masses 7, 8 accommodated in the portions 6a,06b respectively, may be subjected to pressure on either side. It is thereby possible to move the masses 7, 8 to any desired angular position relative to each other. In this case also, as in FIG. 1, as soon as the flow of pressure fluid is stopped, the masses 7, 8 move away from each other until they again lie diametrically opposite one another in abutment with the respective walls 10, 11, thus eliminating the imbalance.

The above descriptions are in no way intended to limit the scope of the present invention but serve merely to illustrate the currently preferred embodiments. The design of the vibrator may evidently be changed as necessary to suit particular requirements.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other type of vibrating rollers, vibrating plates or other vibratory articles differing from the types described above.

While the invention has been illustrated and described as embodied in a vibrator, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore such adaptations should and are inteded to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to the protected by Letters Patent is set forth in the appended We claim:

1. in an apparatus for producing vibrations, a combination comprising wall means defining an annular channel; at least one mass accommodated in and movable circumferentially of said channel; moving means for effecting movement of said mass circumferentially of said channel to respective locations therein; abutment means in said channel for impeding said movement of said mass in excess of a predetermined portion of arc; and a source of pressure fluid, and conveying means for conveying said fluid from said source into said channel.

2. An apparatus as defined in claim 1; further comprising at least one additional mass within said channel.

3. An apparatus as defined in claim 2; and further comprising fastening means fastening one of said masses to said wall means at a location of said channel which is diametrically opposite said abutment means.

4. An apparatus as defined in claim 2, wherein said abutment means comprises abutment elements fast with said wall means, extending at least partly across said channel and dividing said channel into portions.

5. An apparatus as defined in claim 4, wherein each of said portions accommodates one of said masses.

6. An apparatus as defined in claim 1, wherein said mass is of cylindrical form.

7. An apparatus as defined in claim 11, wherein said wall means comprises a mounting portion mounting said wall means for rotation about an axis; and wherein said channel surrounds said axis.

8. An apparatus as defined in claim 7, wherein said channel is concentric with an axis.

9. An apparatus as defined in claim 7, wherein said mounting portion comprises shaft, and a hub provided on said shaft and having two axial ends; and wherein said wall means comprises a pair of discs each surrounding said shaft adjacent one of said axial ends and having a diameter greater than that of said hub, and a circumferential wall connected with the outer peripheries of said discs and defining with the latter and with said hub said annular channel.

10. An apparatus as defined in claim 11, wherein said abutment means comprises tow abutment elements provided at diameterically opposite locations of said channel.

11. An apparatus as defined in claim 1, wherein said abutment means comprises at least one bolt fast with said wall means and extending at least partly across said channel.

12. An apparatus as defined in claim 1, wherein said abutment means comprises two dividing walls fast with said wall means, extending at least partly across said channel and dividing said channel into two portions.

13. An apparatus as defined in claim 12 wherein said conveying means comprises at least one inlet and one outlet passage provided in said shaft, and connecting means connecting said passage with said source; and further comprising at least one transverse passage provided in each of said dividing walls and connecting means connecting said inlet passage with said transverse passage of one of said dividing walls and said outlet passage with said transverse passage of the other of said dividing walls.

14. An apparatus as defined in claim 13, wherein each said transverse passage communicates with said channel on both sides of the respective dividing wall.

15. An apparatus as defined in claim 11, wherein said conveying means comprises at least one inlet and one outlet passage provided in said shaft, and connecting means connecting said passage with said source.

16. An apparatus as defined in claim 15, wherein said passages communicate with said channel.

17. An apparatus as defined in claim 1, wherein said source is a reversible pump.

18. An apparatus as defined in claim 1, wherein said conveying means comprises at least one inlet and one outlet passage provided in said shaft, and connecting means connecting said passage with said source; and wherein said passages communicate with said channel on opposite sides of said one mass.

Pa NO, 3,783,701 Dated January 8, 1974 Inventor) Werner Steprath et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 1, line 9, "and", first occurrence, should read said moving means including 1 Claim 7, line 1, "11" should read l Claim 10, line 1, "11" should read l line 2, "tow" should read two line 3, "diameterically" should read diametrically Claim 13, line 3, cancel "provided in said shaft"; l5 line 1, "11" should read 9 Claim 18, line 1, "1" should read 3 line S, cancel "provided in said shaft"; line 4, "passage" should read passages Signed and sealed this 29th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON .JR. C. MARSHALL DANN Attestlng Officer 7 Commissioner of Patents FORM FWD-1050 (10-69) USCOMM-DC sows-ps9 U.S GOVERNMENT PRINYING OFFICE: 9 93 o