Fluid-Operated Supporting Arrangement and a Conduit Breakage Safety Device

The present invention relates to a fluid-operated supporting arrangement for a travelling mechanism having a plurality of wheels or wheel sets. It also generally relates to a safety device for pairs of any conduits.

Arrangements and devices of the above mentioned general type are known in the art. In a known pneumatic or hydraulic supporting arrangement there are a plurality of pneumatic or hydraulic supporting elements, such as cylinder-and-piston units, which support individual wheels or wheel sets and are connected in groups with one another and/or with a pneumatic or hydraulic accumulator via pairs of conduits which are provided near the supporting element or the accumulator with conduit breakage safety devices reacting to breakage of conduits. In conventional constructions, when one conduit of a pair of broken, the operational ability of the hydraulic or pneumatic mechanism, particularly the travelling mechanism, is maintained by the conduit breakage safety device, inasmuch as the broken conduit is blocked for preventing further losses of pneumatic or hydraulic medium. The remaining, unbroken conduit is sufficient in some cases for the operation of the arrangement. One such conduit breakage safety device for hydraulic travelling mechanisms is disclosed, for example, in German Pat. No. 2,319,611. In this device, two hydraulic cylinders are connected with one another by two separate, parallel-arranged conduits which communicate with the cylinders with interposition of a three-way valve. One passage of the three-way valve leads to the associated cylinder, whereas the two other passages lead to the conduits connected in parallel. The safety valve includes a common closing member for both conduit passages, which in its intermediate position opens both conduit passages and, during breakage of one conduit, displaces under the action of the thus produced flow pulse for blocking the passage leading to the not-tight conduit. In this safety device, the valve-closing member displaces when the flow to one conduit passage is stronger than that to the other conduit passage. Thereby, the displacement of the closing member increases the resistance of the flow to one conduit passage, and reduces the resistance of the flow to the other conduit passage. As a result of this, vibrations which take place during the travel and insignificantly different flow forces to both conduit passages can be increased, and therefore undesirable chatter vibrations of the connecting parts can take place. This reduces the operational safety of the conduit breakage safety device.

Accordingly, it is an object of the present invention to provide a fluid-operated supporting arrangement and a conduit breakage safety device for pairs of conduits, which avoid the disadvantages of the prior art.

More particularly, it is an object of the present invention to provide a fluid-operated supporting arrangement and a conduit breakage safety device which guarantee an especially reliable blocking of the broken conduit.

In keeping with these objects, and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a fluid-operated supporting arrangement and/or a safety device in which conduit of each pair opens separately from the other conduit of the same pair into an associated fluid element such an associated fluid-operated supporting element or an accumulator, and is closable there by its own closing member which, advantageously, forms a pressurecontrol means.

In such a construction, displacement of a closing member associated with one conduit of a pair does not produce any direct action upon the closing member of the other conduit of the same pair. Moreover, the pressure control makes it possible to maintain the closing member below critical pressure fluctuations which, when overcome, require blocking of a conduit. The inventive construction also provides for considerably improved reproducibility of conditions of the conduit breakage safety device.

In accordance with another advantageous feature of the present invention, the closing member or a piston actuating the closing member for each conduit is displaceably arranged in a cylinder chamber, wherein one subchamber associated with one actuating face (front face) of the piston communicates with the associated conduit, whereas the other subchamber associated with the other actuating face (rear face) of the piston is connectable with the other conduit. The pressure of a conduit to be secured by a piston acts upon the front side of this piston and loads the rear side of the piston against the pressure of the other conduit. Since in the conduits of the pair of conduits practically identical pressure conditions prevail during normal operation, the pistons are subjected at both their actuating faces to practically identical or fixed and identically maintained conditions of opposite pressures. Any significant deviations of the pressure conditions take place first during breakage of one of the conduits, or in other words the piston displaces in its closing position when the pressure in a conduit secured by the piston considerably falls as a result of the conduit breaking.

When a travelling mechanism or vehicle runs on surface waves, individual wheels or wheel sets of one group perform upward movements whereas the wheelsor wheel sets of the other groups perform downward movements. Great pressure-medium quantities are conveyed from one supporting element to another supporting element, and in some cases to a pressure-medium accumulator serving for spring-suspension purposes. These pressure-medium streams are connected with different pressures in the supporting elements or in the accumulator and the conduits. For preventing blocking of conduits during acceptable pressure variations, the pistons can be loaded, for example by spring means, to its open position and/or formed as differential pistons whose smaller actuating face is loaded by a reference pressure, for example by a pressure from the other conduit.

In accordance with still another especially advantageous feature of the present invention, for travelling mechanisms as well as for other arrangements, the inventive safety device has a housing with separate passages having a connecting passage for a consumer, particularly a supporting element or an accumulator, and a connecting passage to a conduit connected with the first-mentioned connecting passage, and a piston-actuated closing member with a piston displaceable in a cylinder chamber whose one end communicates with a reference pressure source and whose other end is connected with the associated conduit in closed and open positions of the closing member.

Still a further advantageous feature of the present invention is that the piston itself is formed as a closing member and arranged in a cylinder chamber which opens into a communication path between the above-mentioned passages. In this construction, the safety device can be provided with a relatively small number of bore holes in its housing.

It is especially advantageous for this purpose when the passages for each conduit of the pair are located at an angle relative to one another, preferably normal to one another, and the cylinder chamber forms an extension of the passage in the housing.

The cylinder chamber may be formed as an opening which extends from one housing side and closed at this side, wherein the opening is formed as an extension of the passage with formation of a shoulder, and the other passage opens radially or laterally into this opening. The piston arranged in this cylinder chamber abuts in its end position against the shoulder and closes an inlet of the second-mentioned passage. In another end position spaced from the shoulder, the piston opens the inlet of the second-mentioned passage.

The pistons can have any practically suitable form, and their dimensions must be sufficient to overlap in the closing position the inlet of the passage which opens into the abovementioned opening.

The novel features which are considered 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.

FIG. 1 is a fluid-operated supporting arrangement for a travelling mechanism, in accordance with the present invention;

FIG. 2 is a view showing a section of a conduit breakage safety device in accordance with the present invention;

FIG. 3 is a plan view of a conduit breakage safety device of FIG. 2, taken in direction of the arrow 3 in FIG. 2;

FIG. 4 is another arrangement of the invention; and

FIG. 5 is a further arrangement of the invention according to FIG. 1.

A vehicle shown in FIG. 1 has wheels 2 and 3 arranged one behind the other. The wheels 2 and 3 are suspended in a vertically adjustable manner on the vehicle 1 with the aid of links 4 and 5 of suitable construction. The links 4 and 5 are pivotally connected with one another and with the vehicle 1 by a member 6. Each link 4 and 5, and the associated wheel 2 or 3, is supported by a respective one of supporting elements 7 and 8 on the vehicle 1.

Each of the supporting elements 7 and 8 has a piston 9 and a cylinder 10 in which the piston 9 displaces. The cylinders 10 are connected with one another by conduits 11 and 12, for equalization purposes. The conduits 11 and 12 can be connected via conduits 13 and 14 with further supporting elements or with a not shown accumulator for pressure medium.

When the vehicle 1 runs over a surface wave, for example the wheel 2 displaces in an upwards direction. The piston 9 of the supporting element 8 displaces the pressure medium from the associated cylinder 10 into the cylinder of the other supporting element 7, and thereby causes a downward movement of the wheel 3 relative to the vehicle 1. By this equalization, a uniform distribution of the supporting load of the vehicle 1 takes place during the operation of the arrangement.

For the case when one of the conduits 11 or 12 is broken, a conduit breakage safety device 16 is arranged on the cylinders 10. It blocks in the respective cases the broken conduit 11 or 12 so that the supporting elements 7 and 8 communicate with one another only via the other conduit, 12 or 11.

The conduit breakage safety device 16 is shown in FIGS. 2 and 3 and has a square housing 17 in which parallel openings 18 extend from its one side. The openings 18 open in coaxial passages 19. Between the openings 18 and the passages 19 a constriction 20 is provided so as to form, between the constriction 20 and the openings 18, an annular shoulder 21.

Transverse passages 22 extend from one housing side radially to the openings 18 and open in the vicinity of the annular shoulders 21 into the openings 18.

As considered in FIG. 2, the upper portion of the left opening 18 is connected via a bore hole 23 with the right constriction 20. In the same manner, the upper region of the right opening 18 is connected via a bore hole 23' with the left constriction 20. The openings 18 are closed at the outer side of the housing by threaded closures 35.

Cup-shaped pistons 45 are displaceably arranged in the openings 18. The cup-shaped openings of the pistons face toward the annular shoulders 21 and receive helical springs 22. The springs 22 abut against the annular shoulders 21 and urge displacements of the pistons 45 against abutment pins 47 associated with the threaded closures 35.

The pistons 45 can be displaced against the pressure of the springs 46 until they abut against the annular shoulders 21. In this case, inlets of the transverse passages 22 in the openings 18 will be closed. The inlets of the bore holes 23 and 23' in the openings 18 remain open, even in the position in which the pistons 45 abut against the abutment pins 47.

The conduit breakage safety device 16 shown in FIGS. 2 and 3 operates in the following manner:

The transverse passages 22 serve as connecting conduits to the cylinders 10 of one supporting element 7 or 8 in FIG. 1, on which the conduit breakage safety device is arranged. Each of the conduits 11 or 12 is connected with a respective one of the passages 19 and 20, so that each conduit communicates in the upper end position of the pistons 45 with the associated supporting element 7 or 8. The pressure acting on the constrictions is present also as a reference pressure in subchamber 58 of the openings 18, the subchamber 58 located at the piston side facing toward the threaded closures 35. This takes place because the subchambers 58 are connected via the bore holes 23 and 23' with the respective restrictions 20 so that the pressure equilibrium, regardless of the throttling losses, is provided between the left restriction 20 and the right subchamber 58, as well as between the right restriction 20 and the left subchamber 58.

When the conduits connected with the passages 19 are intact, the state of equilibrium during flow of the pressure medium prevails in the above-mentioned passages and constrictions 20, inasmuch as the communicating conduits as well as their connecting paths from the passages 19 to the passages 22 have identical geometries.

Identical pressures act upon the front and rear sides of the pistons 45, and the springs 46 can hold the pistons 45 in the upper end position shown in FIG. 2.

When the pressure, for example in the left passage in FIG. 2, drops because of breakage of the associated conduit, the respective piston 45 displaces toward a subchamber 57 associated with the respective restriction 20 of a respective opening 18. Thereby, the inlet of the respective transverse passage 22 in the respective opening 18 is closed, and the communication from the left passage 19 to the left transverse passage 22 is blocked.

The displacement of the left piston 45 takes place when its rear side is loaded by pressure in the right restriction 20 which communicates with an intact conduit, since the above-mentioned constriction 20 is in communication via the bore hole 23 with the subchamber 58 of the left opening 18.

As a result of this, in the event of conduit breakage of one of the conduits 11 and 12, the defective conduit is blocked, whereas the conduit which remains unbroken serves for communication of the coupled supporting elements 7 and 8 with one another.

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

While the invention has been illustrated and described as embodied in a fluid-operated supporting arrangement and a conduit breakage safety device, 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.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

In the modified embodiment of the invention according to FIG. 4 a second fluid element 7a is a hydraulicly or pneumaticly operated fluid element with a piston 9a urged by a spring 9b and a safety element 16a acting principally as the safety element 16.

In the modified embodiment of the invention according to FIG. 5 the connecting conduits 11 and 12 of one pair of fluid supporting elements 7 and 8 are connected to a safety element 16a associated to a hydraulic or pneumatic accumulator 7a corresponding to the accumulator according to FIG. 4.

In place of the piston 9a and the spring 9b may be arranged a gas filled compressible hollow body for example a ballshaped body acting like the piston 9a and the spring 9b.

Alternatively such shock absorbating elements may be arranged in the supporting elements 7 or 8 respectively.