Spring system

The present disclosure relates to a spring system comprising a strut for arrangement between a dolly and a body of a rail vehicle with a cylinder and a piston displaceably received in the cylinder which bound a piston chamber, with the piston or the cylinder being connectable to the dolly and the other of the components being connectable to the body and with one or more spring which cushion the body with respect to the dolly, with a non-resilient hydraulic system which is in communication with the piston chamber and by means of which the amount of the hydraulic medium in the piston chamber can be varied for the purpose of adjusting the strut length, with an abutment member being provided by means of which the end position of the piston can be changed in the cylinder and with means being provided which are made such that the means actuates the abutment member when the piston chamber of the hydraulic system is pressure-less or the pressure in the piston chamber or in the hydraulic system falls below a value.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Utility Model Application Serial No. 20 2005 009 909.0 filed Jun. 23, 2005, which is hereby incorporated by reference in its entirety for all purposes.

FIELD

The present disclosure relates to a spring system comprising a strut for arrangement between the dolly and body of a rail vehicle with a cylinder and a piston displaceably received in the cylinder which bound a piston chamber, wherein the piston or the cylinder can be connected to the dolly and the other of the components can be connected to the body.

BACKGROUND AND SUMMARY

So-called hydropneumatic struts are known from the prior art which have a cylinder and a piston longitudinally displaceably received in the cylinder and whose piston chamber is in communication with a hydraulic accumulator. The hydraulic accumulator is generally a hydraulic accumulator containing hydraulic fluid and moreover containing a compressible gas volume. On a movement of the rail vehicle, hydraulic fluid is guided out of the piston chamber into the hydraulic accumulator or out of the hydraulic accumulator into the piston chamber, with the said compressible gas volume having resilient properties so that the hydropneumatic strut acts as a spring element. In this connection, each hydropneumatic strut is typically connected to its own hydraulic accumulator, whereby a comparatively complex design results.

It is the object of the present disclosure to provide a spring system of the first named type which has a simpler structure.

This object may be solved by a spring system having a strut for arrangement between a dolly and a body of a rail vehicle, the strut having a cylinder and a piston displaceably received in the cylinder which bound a piston chamber, with the piston or the cylinder being connectable to the dolly and the other of the components being connectable to the body and with one or more springs which cushion the body with respect to the dolly. Further, a non-resilient hydraulic system is provided which is in communication with the piston chamber and by means of which the amount of the hydraulic medium in the piston chamber can be varied for the purpose of adjusting the strut length. Furthermore, an abutment member is provided by means of which the end position of the piston in the cylinder can be changed, with means being provided which are designed such that they actuate the abutment member when the piston chamber or the hydraulic system is pressure-less or when the pressure in the piston chamber or in the hydraulic system falls below a value.

The hydraulic system in communication with the piston chamber does not have any resilient properties. The first named hydraulic accumulators known from the prior art may not be provided. It rather serves the adjustment of the strut length and thus the variation of the vehicle height between different operating states such as between the traveling operation and the standing of the rail vehicle at the station.

The suspension of the rail vehicle is thus not ensured by the piston-in-cylinder unit or by the hydraulic system in communication with it, but is ensured by one or more springs which cushion the body with respect to the dolly.

If it is found that the pressure in the hydraulic system or in the piston chamber drops below a limit value or if the system becomes pressure-less, the abutment member is actuated, which has the result that the end position of the piston in the cylinder is changed. In emergency operation, the actuated abutment member has the result that the piston can no longer be moved so far into the cylinder as is the case with a non-actuated abutment. A minimum vehicle height is ensured in this manner.

The abutment member can be made displaceable in the direction of movement of the piston or in a direction extending obliquely or perpendicular thereto. It is possible that the piston has a hollow space at least sectionally and that the abutment member is made displaceable relative to the hollow space of the piston. Provision can be made in this connection for the abutment member to be made such that it can be displaced between a moved-in and a pushed-out state, with it being located completely in the hollow space of the piston in the moved-in state. In this state, the abutment member thus has no influence on the piston position.

Provision is made in a further aspect of the present disclosure for the abutment member, the cylinder and the piston to be arranged concentrically to one another.

Provision is made in a further aspect of the present disclosure for the cylinder to have a section of larger diameter and a section of a diameter smaller with respect to it, with the piston being guided in both sections. It is possible that the cylinder and/or the piston has/have one or more seals which prevent a discharge of hydraulic medium from the piston chamber. The guidance of the piston in the section of the cylinder having a larger diameter can be achieved by a peripheral ring located in the end region of the piston, having bores for the passage of the hydraulic medium and furthermore serving as an abutment for the piston movement.

In a further aspect of the present disclosure, a hydraulic accumulator is provided which can be connected to a space which is arranged in the abutment member and/or is adjacent to the abutment member. The means for the actuation of the abutment member has the result that the medium flows out of the hydraulic accumulator into the said space, which in turn has the result that the abutment member is pushed out. Provision is made in a preferred aspect for this space to be adjacent to the abutment member in its end region remote from the piston chamber.

In a further aspect of the present disclosure, a check valve is provided which is arranged such that it permits a flow from the hydraulic accumulator into the space and suppresses a flow from the space into the hydraulic accumulator. It is ensured in this manner that in emergency operation, that is when the piston chamber or the hydraulic system is pressure-less or the pressure in the piston chamber or in the hydraulic system falls below a predetermined value, the abutment member remains in the actuated state in which the piston can no longer be moved fully into the cylinder, but remains in a moved-out position and thus ensures that the spacing between the body and the dolly, and thus the vehicle height, maintains a specific minimum value.

Provision is made in a further aspect for the means actuating the abutment member to comprise pressure-controlled valves. These valves are made such that they establish or cancel a connection between the said hydraulic accumulator and the space which is adjacent to the abutment member or extends in the abutment member.

Provision can furthermore be made for the means actuating the abutment member to be electrical. An embodiment is possible in which pressure sensors are arranged which sense the pressure and control valves accordingly directly or indirectly by means of a control unit such that a connection is established between the hydraulic accumulator and the space.

Provision is made in a further aspect of the present disclosure that the one or more springs are connected in series to the cylinder with the piston that is to the unit of cylinder and piston.

The springs can be one or more coil springs. It is possible that a plurality of springs are provided which are arranged concentrically to one another and/or to the piston-in-cylinder unit.

In a preferred aspect of the present disclosure, the springs extend between the cylinder and the body or between the cylinder and the dolly.

Provision is made in a further aspect of the present disclosure for the springs to be one or more coil springs extending between spring plates and for at least one further spring to be located in series with one of the spring plates and/or in the region between the cylinder and one of the spring plates. The spring located in series with one of the said spring plates can, for example, be a multilayer spring, for example a rubber spring. The spring extending between the cylinder and one of the spring plates can, for example, be a spring having a hollow space which is elastically deformed as required.

DETAILED DESCRIPTION

FIG. 1shows the strut of the present disclosure in a longitudinal sectional representation which is arranged between the dolly and the body of a rail vehicle. The strut has a cylinder10and a piston20displaceably received in the cylinder10. The cylinder10and the piston20bound the piston chamber22which is filled with a suitable hydraulic medium. The supply and the removal of hydraulic medium from the piston chamber22takes place by means of the line23which extends through the piston22, as can be seen fromFIG. 1. The piston20has a substantially cylindrical section and a plate-shaped section20′ forming its upper boundary.

The cylinder10has an upwardly arranged section of smaller internal diameter and a section of larger internal diameter arranged further below. Seals which seal which piston chamber22are located in the section of smaller diameter in the peripheral direction on the inner side of the cylinder10. The piston20contacts the section of the cylinder having a larger internal diameter by means of a ring arranged in the lower end region of the piston20. The ring serves, on the one hand, for the guidance of the piston20in this region and, on the other hand, forms an upper abutment for the piston20. The ring has a bore which has the effect that the hydraulic medium in the piston chamber22can flow from the region above the ring into the region below the ring and in the reverse direction.

The cylinder10has a spring plate12in its upper end region. Two coil springs50,52extend between the spring plate12and a further spring plate12, are arranged concentrically to one another and both support the cylinder10with respect to the spring plate12shown at the bottom.

While the upper spring plate12is an integral component of the cylinder10, the lower spring plate12is formed by a separate component.

The further spring54, which is made as a hollow spring, is located in the region between the lower spring plate12and the cylinder10. The rubber spring56consisting of a plurality of layers is located below the lower spring plate12, as can be seen fromFIG. 1.

The piston20has a hollow space24in which the abutment member40is longitudinally displaceably arranged. The abutment member40is movable in the hollow space24of the piston20in the same direction as the piston20is movable in the cylinder10.

In the normal operation shown inFIG. 1, the abutment member40is completely retracted into the hollow space24of the piston20so that it does not project beyond the lower surface of the piston20facing the piston chamber22.

As can further be seen fromFIG. 1, a space80is located in the abutment member40which is in communication with a line81by which the space80is fed with a suitable medium, preferably with the same hydraulic medium as the piston chamber22.

The spacing between the piston20and the cylinder10, and thus the car height, can be changed by changing the volume of the hydraulic medium located in the piston chamber22. The hydraulic system30visible fromFIG. 4serves this purpose. It is hydraulically connected to all four struts which cushion the body with respect to the dolly. The hydraulic system is designated with reference numeral30and is in each case in communication with the piston chambers22of the struts. If the car height should be reduced, the valves visible fromFIG. 4are switched such that the hydraulic system30is connected to a low-pressure system30′ which has the result that hydraulic medium is drawn out of the piston chambers22and the vehicle height is reduced. The necessity to reduce the car height can be present, for example, when the rail vehicle is standing at a station so that passengers can get on and off easily.

If the car height should be increased, the hydraulic system30is connected to the high-pressure system30″, which is achieved by a corresponding connection of the valves shown inFIG. 4. In this case, hydraulic medium flows from the system30″ into the hydraulic system30and via this into the piston chamber22until the desired vehicle height has been reached which is desired, for example, for travel operation. The high-pressure hydraulic system30″ is fed by a variable delivery pump which is in communication with the low-pressure hydraulic system30′ on the suction side, as can be seen fromFIG. 4.

The hydraulic system30in accordance withFIG. 4is made non-resiliently. In the particular embodiment shown in the figures, it has no hydraulic accumulators known from previously known systems which take over suspension during travel operation. Provision is made in moving operation, for example, for the volume of the hydraulic medium in the piston chambers22to remain constant so that the hydraulic system30,30′ and30″ is not flowed through during travel operation but is static if no change is made to the vehicle height. A throughflow of the hydraulic system in the one direction or the other preferably only takes place when the vehicle height should be reduced after driving into a station or when the vehicle height should be increased again after the passengers have got on or off. A vehicle height adjustment is naturally also possible during travel operation.

If a pressure drop occurs in the hydraulic system30, this can have the result that the piston20lies on the base plate of the cylinder10. This state is shown inFIG. 2. A state of this type results in a very low vehicle height which can be critical for safety and can, in such a case, even have the result that the rail vehicle is derailed.

In order also to ensure an adequate minimum height of the vehicle in case of an emergency, an emergency system is provided which will initially be explained in accordance withFIG. 4. The emergency system has a hydraulic accumulator70which is fed from the high-pressure hydraulic system30″. This means that the same pressure is present in the hydraulic accumulator70as in the high-pressure hydraulic system30″. In normal operation of the vehicle, the valve90located in the outlet line of the hydraulic accumulator70is connected such that the hydraulic accumulator70is closed, that is that the hydraulic medium located in it cannot flow out. If a pressure drop occurs in one of the systems30,30′ or30″, this has the result that the hydraulic accumulator70is connected to the space80by means of the valve90then connected in accordance withFIG. 1. This has the result that the hydraulic medium standing under high pressure flows out of the hydraulic accumulator70into the space80and pushes out the abutment member40relative to the piston20, as is shown inFIG. 3. In this state, the end face of the abutment member40facing the piston chamber22lies on the base plate of the cylinder10, as is shown inFIG. 3. The hydraulic medium which stands under high pressure, ensures that the vehicle height does not fall below the level shown inFIG. 3and has flown out of the hydraulic accumulator70is located in the space80which is composed, on the one hand, of the hollow space of the abutment member40and of the space located above the abutment member40, as is shown inFIG. 3. To prevent hydraulic medium from flowing out of the space80back into the hydraulic accumulator70, a check valve92can be provided at a suitable site which admittedly permits the filling of the space80from the hydraulic accumulator70, but prevents the flow in the reverse direction.

In addition to or instead of the pressure-controlled valve90shown inFIG. 4, electrical valves can also be provided which are actuated correspondingly to the extent that pressure sensors arranged at a suitable site determine a pressure drop or the pressure-less state.