The invention relates to a gas cylinder, in particular a high-pressure gas cylinder. The cylinder tube of the gas cylinder has a piston rod that is passed through a sealing arrangement sealing the gas pressure prevailing in the pressure chamber of the cylinder tube against the ambient pressure.
Such gas cylinders, as a kind of plunger cylinder, can be advantageously used as an energy storage cylinder in devices for energy recovery, among other things. As is disclosed by way of example in DE 10 2008 034 582 A1, in such applications, the piston rod of the gas cylinder is connected to a movable element of an associated work tool. The movable element may be the boom of an excavator or of a machine for material handling or the like, for example. When lowering the movable element, the potential energy of the movable element and the load connected thereto is stored by the gas cylinder to provide at least partial compensation for the respective equipment weight when the movable element is raised again.
In the case of the higher pressures prevailing in the pressure chamber during operation, sealing the gas pressure against the ambient air is very difficult, even in the case of a working gas having relatively large molecules such as N2. Preventing gas losses with conventional sealing systems is scarcely possible.
An object of the invention is to provide an improved gas cylinder that offers increased security against gas losses.
According to the invention, this object is basically achieved by a gas cylinder having, as an essential feature of the invention, a sealing arrangement with multiple sealing elements, which are operationally subordinate to one another. An oil pressure chamber is formed between a sealing element located closer to the pressure chamber and a sealing element located further from the pressure chamber. Oil can be compressed in the oil pressure chamber by a supply device at a pressure that is equal to or higher than the respective gas pressure prevailing in the pressure chamber of the cylinder tube. The sealing element adjacent to the pressure chamber thus does not seal the working gas against the ambient air, but rather against the oil that is at the same pressure level. The high-pressure oil that is located in the oil pressure chamber is sealed against the environment by the additional sealing element. Thus, the sealing objective is divided into two manageable subtasks so that the greatest possible security against gas losses is achieved.
In an especially preferred embodiment of the gas cylinder arrangement according to the invention, the piston rod has a sliding element that can be moved in the cylinder tube. The piston rod is securely guided and supported at two opposing end regions within the cylinder tube. In this way, unimpeded operation is made possible.
In especially advantageous embodiments, the sealing elements of the sealing arrangement and the oil pressure chamber located therebetween are disposed in a fixed positional relationship to one another. This positioning permits realizing the sealing arrangement in its entirety in a uniform component that forms an integral part of the cylinder tube.
Especially advantageously, the supply device for the oil pressure chamber has a hydraulic accumulator. The oil side of the accumulator contains sealing oil and can be connected to the pressurized oil chamber. The gas side of the accumulator can be connected to the pressure chamber of the cylinder tube. The gas pressure in the pressure chamber is thereby utilized in an advantageous manner for the pressure supply of the foil pressure chamber, which leads to an especially simple and reliable structure of the supply device.
In advantageous embodiments, the supply device has an oil connection for refilling the sealing oil to the oil side of the hydraulic accumulator. A device is preferably available for monitoring the quantity of sealing oil during operation. In this regard, at least one pressure sensor may be provided, which signals the oil pressure prevailing in the oil pressure chamber of the sealing arrangement.
The hydraulic accumulator of the supply device can be advantageously designed in the form of a piston accumulator.
The use of a piston accumulator opens up the advantageous possibility of mechanically preloading the piston of the piston accumulator for movement in the direction toward the oil side, for example by a spring arrangement. In the event of gas pressure of the pressure chamber in the cylinder chamber prevailing on the gas side of the piston accumulator, a correspondingly higher pressure level arises in the oil pressure chamber due to the mechanical preloading of the accumulator piston. The sealing element sealing against the gas pressure is then appropriately pressure-supported in an advantageous manner.
In especially advantageous embodiments, the piston accumulator is integrated into the end piece of the cylinder tube containing the sealing arrangement in such a way that the gas side of the accumulator cylinder is open to the pressure chamber of the cylinder tube. The gas cylinder, including the sealing arrangement supported by oil pressure and the associated supply device, thereby forms a closed assembly without external auxiliary units.
The configuration may be advantageously carried out in such a way that the accumulator cylinder is formed in the end piece by an annular space adjacent to the pressure chamber. The annular space encloses the piston rod and contains an annular piston. With the given external dimensions of the cylinder tube and the end piece thereof, a large volume is thereby advantageously available for the piston accumulator, and therefore, a large oil supply for supplying the oil pressure chamber.
On the one hand, a larger volume of gas is available in the case of embodiments in which a hollow piston rod in the form of a straight length of tubing is provided. The inner end of the hollow piston rod is open to the pressure chamber of the cylinder tube. On the other hand, with the given external dimensions and stroke lengths of the cylinder, the total gas volume in the extended position, as well as the change in volume that can be achieved by the displacement movement, can be freely adjusted by the dimensioning of the diameter of the piston rod (inner diameter and outer diameter) and the cylinder tube. The force-stroke characteristic of the gas cylinder can thereby be advantageously influenced.
In especially advantageous embodiments, the sliding element at the end of the piston rod has a piston-shaped guide component. This guide component may have gas outlets, which have a choke effect on displacement movements when outlets are selected that have a small cross section, or which have no choke effect on displacement movements in the case of a large-scale shape. The sliding element then purely fulfills a guiding function on the inside of the cylinder tube.
The guide component may be non-circular, and may be designed in such a way that it is guided along the wall of the cylinder tube only at corner regions. Sliding guides may then be provided at the corner regions and/or on the inner wall.
Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, discloses preferred embodiments of the present invention.
Referring to the drawings that form a part of this disclosure:
The embodiment shown in
As can clearly be seen in the partial section of
Specifically, as shown in
The oil pressure chamber 33 serves to accommodate high-pressure oil, which is pressurized to at least the same degree as the gas pressure prevailing in the cylinder tube 1. In the present case, a supply device in the form of a hydraulic accumulator 37 is provided to supply the oil pressure chamber 33. The oil side 39 of hydraulic accumulator 37 is directly connected to the oil pressure chamber 33 by a connection 41. The gas side 43 of the hydraulic accumulator 37 is connected to the annular space 23 of the cylinder tube 1 by a connection 45. The hydraulic accumulator 37 is preloaded with the gas pressure prevailing in the cylinder tube 1, so that the hydraulic accumulator 37 maintains a corresponding oil pressure in the oil pressure chamber 33. The first sealing element 31 seals the gas against the oil with the balanced pressure prevailing at the sealing element 31, while the outer, second sealing element 35 seals high-pressure oil against the environment. The sealing task is thus divided into two manageable subtasks, thus reducing the risk of gas loss into the environment.
In the further embodiments to be described below, the sealing arrangement 13 may have more than two axial sealing elements that are axially offset to one another, having a corresponding number of oil pressure chambers located between said sealing elements.
The additional embodiment shown in
The embodiments according to
By contrast,
The following embodiments are only explained insofar as they differ from the embodiments described above. In so doing, for the most part the same reference numerals that were used above will be used for the same components. In this respect, the explanations given above shall also apply to the embodiments described below.
Thus the gas cylinder solution according to
A technical solution of this kind creates a very large accumulator space, formed by the hollow cylindrical recesses within the cylinder tube 1 and the piston rod 9. Other working media, preferably in a gaseous form, may be used instead of the nitrogen working gas, such as noble gases, to be able to optimally adjust the working and storage capacity of the gas cylinder to the given application situation.
The embodiment according to
The embodiment according to
In the case of the embodiment according to
As made clear by the preceding embodiments, the force-stroke characteristic of the gas cylinder can be adjusted in particular by the selection of the outer and inner diameter of the piston rod 9 and the inner diameter of the cylinder tube 1.
While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the claims.
Number | Date | Country | Kind |
---|---|---|---|
10 2011 119 011 | Nov 2011 | DE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2012/004564 | 10/31/2012 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2013/072019 | 5/23/2013 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
274500 | Kline | Mar 1883 | A |
719460 | Goosmann | Feb 1903 | A |
2111792 | Laugaudin | Mar 1938 | A |
2155628 | Williams | Apr 1939 | A |
2737384 | Laugaudin | Mar 1956 | A |
3827700 | Kaller | Aug 1974 | A |
3943717 | Schexnayder | Mar 1976 | A |
5465811 | Katz | Nov 1995 | A |
5607165 | Bredemeyer | Mar 1997 | A |
5964454 | Volpel | Oct 1999 | A |
20130220749 | Stammen | Aug 2013 | A1 |
Number | Date | Country |
---|---|---|
86 160 | Apr 1896 | DE |
869585 | Mar 1953 | DE |
2 248 156 | Apr 1973 | DE |
36 09 189 | Nov 1986 | DE |
10 2008 034582 | Jan 2010 | DE |
102010049750 | Jan 2012 | DE |
1 391 524 | Mar 1965 | FR |
2582368 | Nov 1986 | FR |
S63235770 | Sep 1988 | JP |
WO 2010079227 | Jul 2010 | WO |
Entry |
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Translation of DE869585 from espacenet. |
FR 2582368 machine translation to English from espacenet. 1986. |
JPS63235770A machine translation to English from espacenet. 1988. |
Number | Date | Country | |
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20140230645 A1 | Aug 2014 | US |