US20120291623A1

US20120291623A1 - Working apparatus, in particular excavator or machine for material handling

Info

Publication number: US20120291623A1
Application number: US13/473,281
Authority: US
Inventors: Philipp Egenrieder; Hans-Peter Lavergne
Original assignee: Liebherr Hydraulikbagger GmbH
Current assignee: Liebherr Hydraulikbagger GmbH
Priority date: 2011-05-18
Filing date: 2012-05-16
Publication date: 2012-11-22
Also published as: RU2012118377A; CN102787625A; JP2012241900A; EP2524997A1; EP2524997B1; CN102787625B; DE102011106260A1

Abstract

The present disclosure shows a working apparatus, in particular an excavator or a machine for material handling, having an element movable via at least one hydraulic working cylinder, wherein at least one energy recovery cylinder is provided for recovering energy from the movement of the movable element, said energy recovering cylinder being filled with gas at the base side and having an annular space filled with a medium. In this respect, a flow restricting element is provided which restricts the flow of the medium from the annular space on a sudden moving out of the piston rod.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 10 2011 106 260.6, entitled “Working apparatus, in particular excavator or machine for material handling”, filed May 18, 2011, which is hereby incorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

The present disclosure relates to a working apparatus, in particular to an excavator or to a machine for material handling, having an element movable via at least one hydraulic working cylinder, wherein at least one energy recovery cylinder is provided for recovering energy from the movement of the movable element, said energy recovery cylinder being filled with gas at the base side and having an annular space filled with a medium.
Such a working apparatus is known from DE 10 2008 034 582 A1 whose content is made the subject of the present application in full. The energy recovery cylinder is in this respect used, e.g., to store the potential energy on a downward movement of the movable element by compressing the gas in the base side filled with gas which is then again available to support the upward movement again. In the loaded state of the energy recovery cylinder, large amounts of energy are usually stored in the compressed gas in this respect.

BACKGROUND AND SUMMARY

It is the object of the present disclosure to make the operation of a working apparatus such as described above more reliable.
This object is achieved in accordance with the present disclosure by a working apparatus which has an element movable via at least one hydraulic working cylinder, wherein at least one energy recovery cylinder is provided for recovering energy from the movement of the movable element, said energy recovery cylinder being filled with gas at the base side and having an annular space filled with a medium. Provision is made in accordance with the present disclosure in this respect so that a flow restricting element is provided which restricts the flow of the medium from the annular space on a sudden moving out of the piston rod. The present disclosure is in this respect used particularly advantageously in an excavator or in a machine for material handling, in particular in such a machine in which a boom or arm pivotable about a horizontal axis forms the movable element.
The inventors of the present disclosure have recognized in this respect that the high amount of energy which is stored in an energy recovery cylinder in the loaded state can become a safety risk if there is for any reason a defect at the bearing points, the bearing parts of the energy recovery cylinder, or the equipment. To prevent a moving out of the piston rod of the energy recovery cylinder at an uncontrolled speed in the event of such a failure of the bearing points or securing points in which the piston rod is no longer mechanically secured, the flow restriction element is provided in accordance with the present disclosure which restricts the flow of the medium out of the annular space on such a sudden defect. The speed at which the piston rod of the energy recovery cylinder is moved out is hereby simultaneously controlled. Damage to the energy recovery cylinder, to the working apparatus, and to persons can hereby be prevented.
For this purpose, in a first embodiment, the annular space can be in communication via the flow restriction element with an external reservoir in which the medium flows on the moving out of the piston rod. In this respect, in particular an additional container is installed as an external reservoir at the energy recovery cylinder and receives the medium on the moving out of the piston rod and makes the medium available for filling the annular space on the moving in of the piston rod.
In this respect, a medium may be used in the present disclosure which is not compressible. In particular hydraulic oil may be used. The expansion of the energy recovery cylinder can thus be controlled via the flow speed of the non-compressible medium.
A restrictor or diaphragm is advantageously used as the flow restriction element. It is advantageously adjustable so that the flow speed can be set via the restrictor or diaphragm.
A valve unit, in particular a valve unit with an adjustable volume flow, can equally be used as the flow restriction element. A flow control valve or a burst pipe protection can be used for this purpose, for example.
In an alternative embodiment of the present disclosure, the annular space can be in communication via the flow restriction element with the base side of the energy recovery cylinder filled with gas. A gas exchange must thus take place between the annular space and the base side via the flow restriction element to move out the piston rod, whereby the outward movement speed can likewise be controlled.
In this respect, the flow restriction element is advantageously a restrictor. In this respect, a check valve can advantageously be arranged parallel to the restrictor so that the gas flow between the base side and the annular space is not restricted by the restrictor on the inward movement of the piston rod.
In a possible application of the present disclosure, the flow restriction element restricts the flow of the medium out of the annular space independently of the remaining control of the working apparatus and is in particular independent of the control which controls the movement of the movable element.
Furthermore, the flow restriction element can be a passive element, i.e. an element which can be controlled via a control. The flow restriction element thus solely serves the purpose of securing the energy recovery cylinder in the case of damage. A particularly simple and inexpensive design is hereby made possible.
The present disclosure is in particular used in those working apparatus in which the energy recovery cylinder has a hollow piston rod. The working apparatus and the energy recovery cylinder are in this respect advantageously set up as is shown in DE 10 2008 034 582 A1, which is incorporated by reference herein as one example configuration for the working cylinder and energy recovery cylinder of the present disclosure.
Further advantageously, the working device is in this respect a movable working apparatus, in particular an excavator or a machine for material handling. This working apparatus has an element which is movable via at least one hydraulic working cylinder, wherein the energy recovery cylinder serves the energy recovery from the movement of the moving element.
The movable element of the working apparatus in accordance with the present disclosure is advantageously pivotally connected to the working apparatus pivotable about a vertical axis of rotation and is pivotable in a vertical pivoting plane via the hydraulic working cylinder or cylinders. The movable element can in this respect, in particular, be the arm of an excavator or the boom of a machine for material handling. Further advantageously, the movable working apparatus has an undercarriage with traveling gear and a superstructure arranged rotatably about a vertical axis of rotation thereon to which the movable element is pivotally connected.
In this respect, a piece of working equipment, for example a shovel or a grip, can be arranged at the movable element. On the lowering of the movable element, the potential energy of the movable element and of the piece of working equipment is stored via the energy recovery cylinder in order to at least partly compensate the equipment weight on the upward movement of the movable element. Less energy therefore has to be exerted via the hydraulic working cylinders to move the movable element upwardly.
The energy recovery cylinder in accordance with the present disclosure is in this respect advantageously arranged like the hydraulic working cylinder or cylinders between the superstructure of the working apparatus and the movable element. The energy recovery cylinder thus moves parallel with the hydraulic working cylinder on a movement of the movable element. The working apparatus can be designed as is shown in more detail in DE 10 2008 034 582 A1.
In addition to the working apparatus, the present disclosure furthermore includes an energy recovery cylinder for a working apparatus as described above. The energy recovery cylinder is in this respect filled with gas at the base side and has an annular space filled with a medium, wherein a flow restriction element is provided which restricts the flow of the medium out of the annular space on a sudden moving out of the piston rod. The energy recovery cylinder is in this respect advantageously designed as described above.
The present disclosure further relates to a method of operating a working apparatus, in particular an excavator or a machine for material handling, having an element movable via at least one hydraulic working cylinder, wherein at least one energy recovery cylinder is provided for recovering energy from the movement of the movable element, said energy recovery cylinder being filled with gas at the base side and having an annular space filled with a medium. In accordance with the present disclosure, the method in this respect provides that the flow of the medium out of the annular space is restricted on an unwanted moving out of the piston rod. In this respect, in particular the flow of the medium out of the annular space is restricted when the piston rod is no longer mechanically secured due to a defect at the bearing points or at the bearing parts of the energy recovery cylinder or of the working apparatus so that the energy stored in the energy recovery cylinder would result in an uncontrolled moving out of the piston rod. The moving out of the piston rod is therefore also controlled by the inventive restriction of the flow of the medium out of the annular space in case of damage so that damage to the component and the environment are prevented. The energy recovery cylinder is in this respect advantageously designed and is operated as described above.
The present disclosure will now be presented in more detail with reference to embodiments and to the drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a first embodiment of the present disclosure with a moved out piston rod.

FIG. 2 shows the first embodiment shown in FIG. 1 with a moved in piston rod.

FIG. 3 shows a second embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments of a working apparatus in accordance with the present disclosure will now be described with reference to FIGS. 1-3, which are drawn approximately to scale, although other relative dimensions may be used, if desired. The working apparatus in this respect has at least one element movable via at least one hydraulic working cylinder, with at least one energy recovery cylinder being provided for recovering energy from the movement of the movable element. The energy recovery cylinder in this respect has a base side filled with gas and thus itself serves as an energy store for the energy recovery from the movement of the movable element. On a movement of the piston rod of the energy recovery cylinder, the pressurized gas stored at the base side is compressed in this process. The energy hereby stored is then available again on an upward movement of the piston rod to support the hydraulic working cylinder.
If an energy recovery cylinder in accordance with the present disclosure is in a loaded state, it stores large amounts of internal energy. If a defect occurs for any reason at the bearing points or at other bearing parts of the energy recovery cylinder or at the equipment in this state, the stored energy could be released in an uncontrolled manner without further security. The present disclosure now prevents this stored energy from moving out the piston rod of the energy recovery cylinder at an uncontrolled speed and causing damage to the energy recovery cylinder, to the working apparatus or to the environment.
The two embodiments of the present disclosure shown in FIGS. 1 to 3 are in this respect based on an energy recovery cylinder having a piston rod 1 which is arranged movably in a cylinder jacket 2. The base side 4 of the cylinder jacket is in this respect filled with gas. Furthermore, the piston rod 1 is made hollow and open toward the base side so that the interior 5 of the piston rod 1 is likewise filled with gas.
The recovery cylinder in accordance with the present disclosure is in this respect a two-sided cylinder so that an annular space 6 is furthermore arranged between the piston rod 1 and the cylinder jacket 2. In this respect, a stuffing box 3 is provided which seals the piston rod 1 toward the cylinder jacket 2 and a piston seal 7 is provided which seals the annular space 6 toward the base side 4.
In the first embodiment of the present disclosure shown in FIGS. 1 and 2, the annular space 6 is filled with a non-compressible medium, for example hydraulic oil. In this respect, the annular space 6 is in communication with an external container 9 via a flow restriction element 8. If the pressurized energy recovery cylinder can expand in an uncontrolled manner, e.g. due to a defect in the bearing points, the medium located in the annular space 6 has to flow through the flow restriction element into the external container 9. It is hereby no longer possible for the cylinder to expand in an uncontrolled manner.
The flow restriction element advantageously has a restrictor, a diaphragm or a valve unit. In this respect, the flow speed can advantageously be set by the flow restriction element. The valve unit can in this respect in particular be a flow control valve or a burst pipe protection.
FIG. 1 in this respect shows the energy recovery cylinder in accordance with the present disclosure with a moved out piston rod 1 and thus with a filled additional container 9. FIG. 2 shows the energy recovery cylinder in accordance with the present disclosure with a moved in piston rod 1 and thus with a partly emptied additional container 9.
In the second embodiment shown in FIG. 3, the annular space 6 is, in contrast, filled with gas and is in communication with the base side 4 via the flow restriction element 10. The gas is hereby restricted on the overflow between the annular space 6 and the base side 4 so that an uncontrolled moving out of the piston rod 1 is likewise prevented. In this respect, a restrictor 10 is advantageously used as the flow restriction element. A check valve 11 is advantageously provided parallel hereto and allows a free flow of the gas from the base side 4 into the annular space 6.
The present disclosure thus ensures a controlled expansion or moving out of an energy recovery cylinder under high pressure when it is no longer mechanically secured due to a defect of a bearing part.
While only FIG. 1 shows the working apparatus 21 and working cylinder 23, such components may also be included in FIGS. 2 and 3.

Claims

1. A working apparatus, comprising:

an element movable via at least one hydraulic working cylinder, wherein at least one energy recovery cylinder is provided for recovering energy from a movement of the movable element, said energy recovering cylinder being filled with gas at a base side and having an annular space filled with a medium, wherein a flow restriction element is provided which restricts a flow of the medium out of the annular space on a sudden moving out of a piston rod.

2. A working apparatus in accordance with claim 1, wherein the flow restriction element is in communication with an external reservoir into which the medium flows on a moving out of the piston rod.

3. A working apparatus in accordance with claim 1, wherein the medium is not compressible.

4. A working apparatus in accordance with claim 1, wherein the flow restriction element is a restrictor, a diaphragm and/or a valve unit.

5. A working apparatus in accordance with claim 1, wherein the annular space is in communication with the base side of the energy recovery cylinder filled with gas via the flow restriction element.

6. A working apparatus in accordance with claim 5, wherein the flow restriction element is a restrictor.

7. A working apparatus in accordance with claim 6, wherein a check valve is arranged parallel to the restrictor.

8. A working apparatus in accordance with claim 1, wherein the energy recovery cylinder has a hollow piston rod.

9. A working apparatus in accordance with claim 1, wherein the flow restriction element is a restrictor, a diaphragm and/or a valve unit having an adjustable volume, wherein the working apparatus is an excavator or a machine for material handling.

10. A method of operating a working apparatus, having an element movable via at least one hydraulic working cylinder, wherein at least one energy recovery cylinder is provided for recovering energy from a movement of the movable element, said energy recovery cylinder being filled with gas at a base side and having an annular space filled with a medium, comprising: restricting a flow of the medium out of the annular space during an unwanted moving out of a piston rod.

11. A working apparatus, comprising:

at least one hydraulic working cylinder;

an element movable via the at least one hydraulic working cylinder;

at least one energy recovery cylinder movable in parallel with the hydraulic working cylinder on a movement of the movable element, the energy recovery cylinder having a cylinder jacket and a piston rod for recovering energy from movement of the movable element, said energy recovering cylinder filled with gas at a base side and having an annular space filled with a hydraulic medium; and

a flow restriction element which restricts a flow of the medium out of the annular space on a sudden moving out of the piston rod, the flow restriction element positioned exterior to the piston rod and the cylinder jacket.

12. A working apparatus in accordance with claim 11, wherein the energy recovery cylinder is coupled to the element.

13. A working apparatus in accordance with claim 12, wherein the flow restriction element is a restrictor, a diaphragm and/or a valve unit.

14. A working apparatus in accordance with claim 13, wherein the annular space is in communication with the base side of the energy recovery cylinder filled with gas via the flow restriction element.

15. A working apparatus in accordance with claim 14, wherein a check valve is arranged parallel to the restrictor.