Expansible chamber devices – With linkage or transmission engaging portion intermediate...
Reexamination Certificate
1999-04-29
2001-07-17
Lopez, F. Daniel (Department: 3745)
Expansible chamber devices
With linkage or transmission engaging portion intermediate...
C092S161000
Reexamination Certificate
active
06260470
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydraulic piston-cylinder-unit for a slewing drive, especially to swing working tools, with at least one piston, which can be slid in a cylinder and exhibits fastening means, by means of which the piston can be connected in such a manner to a coupling rod that the working tool can be swung by means of a movement of the piston.
2. Description of the Related Art
Hydraulic piston-cylinder-units are widely used to drive working tools, especially to swing backhoe and face shovels of dredgers. The DE-U-94 07 859 discloses a hydraulically driven dredging shovel, which can be arranged so as to swing on a carrier, arranged on the front end of the boom of a dredger. The swinging motion of the shovel is induced by means of a piston-cylinder-unit, which is arranged in a carrier, located in the upper rim area of the shovel. The carrier is connected to a coupling rod, with which the piston-cylinder-unit engages. The carrier is preferably shaped tubularly and contains the cylinder of the piston-cylinder-unit. Furthermore, the DE-U-296 21 253 discloses a slewing adapter to swing a tool, such as a dredging shovel, wherein the piston-cylinder-unit is envisaged in a coupling mechanism, which can be swung relative to the carrier of the construction machine. In this case, too, the piston-cylinder-unit is located preferably in a tubular carrier.
The end areas of the coupling rod are connected to the carrier of the construction machine and to the piston-cylinder-unit so as to swing. The connection to the piston-cylinder-unit is accomplished usually by means of an extension piece, which is mounted on the piston and which projects beyond the carrier, containing the piston-cylinder-unit.
Such an arrangement has the disadvantage that the extension piece cannot be mounted in principle until after the piston-cylinder-unit has been slid into the carrier. The result is a relatively low degree of prefabrication of the slewing drive, since the extension piece cannot be attached to the piston rod before the cylinder has been installed in a carrier.
SUMMARY OF THE INVENTION
The object of the present invention is to improve a piston-cylinder-unit for a slewing drive to the extent that it is easier to mount.
This problem is largely solved by a piston-cylinder-unit of the aforementioned kind in that the cylinder exhibits fastening means, by means of which the cylinder can be connected to the working tool or to a carrier of the slewing drive. The advantage herein lies in the fact that the extension piece can be mounted, for example, by screwing or welding before the piston-cylinder-unit is attached. The reason for this lies in the fact that, according to the invention, the cylinder of the piston-cylinder-unit is not slid into a carrier, but rather it itself functions as the carrier of the piston-cylinder-unit. This goal is reached in that the cylinder exhibits fastening means, by means of which it can be attached to the working tool or also to the carrier of the slewing drive.
Thus, it is no longer necessary to slide the cylinder into a carrier; and correspondingly it is possible to prefabricate the piston with extension pieces.
Furthermore, there are cost advantages in production, since the piston rod can be produced, according to the invention, as one piece with the welded extension piece. In addition it is possible to make the effective lengths smaller than in prior art slewing drives, since the narrower design of the welded extension piece makes it possible to use a correspondingly narrower cylinder. Another important advantage is the faster assembly and disassembly or the easy replacement of the piston-cylinder-unit.
A preferred embodiment of the present invention provides that the cylinder of the hydraulic piston-cylinder-unit is designed as a twin plunger cylinder. In this case a piston rod is used whose end regions can be moved in one of the end regions of the cylinder.
The chambers of the twin plunger cylinder that are provided at both faces of the piston and are pressure-driven can exhibit different diameters. The resulting advantage lies in the fact that forces can be introduced that vary with the piston's direction of motion in accordance with the different areas; and thus different velocities of the pistons can be realized. Such an arrangement is especially advantageous when the piston-cylinder-unit according to the invention is used with a grabber, since in this case different velocities are often necessary when opening or closing the grabber.
Another embodiment of the present invention provides that the fastening means of the piston are designed as an extension piece, which projects beyond the cylinder and to which the coupling rod can be attached so as to swing. The piston's movement in the cylinder leads to a corresponding movement of the extension piece connected to the piston, thus resulting in a corresponding swinging of the piston-cylinder-unit or a workpiece fastened thereto when the piston moves owing to the coupling rod, hinged to the extension piece.
In addition, the cylinder may exhibit one or several slotted recesses, through which the extension piece extends. The extension piece exhibits a cover element, by means of which the recess can be covered in all positions of the piston. The cover element can be screwed or also welded to the extension piece and serves primarily to prevent the piston-cylinder-unit from becoming dirty. In addition, it prevents an inadvertent engagement with the slotted recess of the cylinder.
According to a preferred design of the present invention, the extension piece is screwed or welded to the piston. One advantage of the welded design lies in the fact that a narrow extension piece can be used that in turn necessitates a narrow cylinder. Another advantage of welding lies in cost reduction. In both cases (screwed or welded) it is possible to attach the extension piece to the piston prior to installation of the piston-cylinder-unit. Especially in this case the resulting advantage is also that the piston-cylinder-unit of the invention can be quicky assembled and disassembled; and, when the requirements change, it can be easily replaced with a piston-cylinder-unit of a different design.
According to a preferred embodiment of the present invention, each opposite side of the piston exhibits one extension piece each, which extends radially from said piston. The resulting advantage lies in the fact that special tools, for example with several components, to be moved synchronously, such as grabbers, can be driven by means of the piston-cylinder-unit of the invention.
Another embodiment of the present invention provides that the piston of the hydraulic piston-cylinder-unit exhibits a cross borehole. In this case the coupling rods of a slewing drive are connected to the piston of the piston-cylinder-unit according to the configuration of the borehole.
Another embodiment of the present invention provides that the fastening element of the cylinder comprises straps, which have boreholes to mount the cylinder. In this case the straps can extend radially from the cylinder or can be configured at any other arbitrary position, for example in the bottom region of the cylinder. The straps are welded preferably to the outer jacket of the cylinder. The boreholes in the straps serve to connect the piston-cylinder-unit to a tool, for example to a shovel, or also to the carrier of the slewing drive.
It is especially advantageous if the cylinder of the hydraulic piston-cylinder-unit of the invention consists of two end members and at least one center member, which is connected to the end members so as to disconnect. Such a design of the cylinder offers the possibility of being able to select freely the length of the cylinder and thus also the slewing angle through the appropriate choice of the center member. The center member is flanged preferably to the end members.
The center member can exhibit the slotted recess, whose purpose serves the passing through of the extension piece of the pis
Jacobson & Holman PLLC
Lazo Thomas E.
Lopez F. Daniel
LandOfFree
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