Road Construction Machine, Crawler Track Unit Of A Road Construction Machine, As Well As Method For Tensioning A Chain Of A Crawler Track Unit

• US 20100237691A1
• Filed: 03/17/2010
• Published: 09/23/2010
• Est. Priority Date: 03/20/2009
• Status: Active Grant

• Current Assignee: Wirtgen GmbH (Deere & Company)
• Original Assignee: Wirtgen GmbH (Deere & Company)
• Inventors: Frank, Burkhard, Busley, Peter, Barimani, Cyrus, Hähn, Günter
• Granted Patent: US 9,016,810 B2
• Time in Patent Office: Days
• US Class Current: 305/146
• CPC Class Codes: B62D 55/065 Multi-track vehicles, i.e. more than two tracks soil-shifting machines E02F; mining machines E21C
• CPC Class Codes: B62D 55/0655 Articulated endless track vehicles steering specially adapted for trailers B62D13/00; articulated buses B62D47/025; tractor-trailer combinations or road trains comprising a uni-axle unit and a uni-axle trailer B62D53/02
• CPC Class Codes: B62D 55/30 Track-tensioning means
• CPC Class Codes: B62D 55/305 acting on pivotably mounted idlers

Abstract

In a road construction machine, in particular a road milling machine (1), with a machine frame (2), and a chassis (4) with preferably several crawler track units (6), said chassis (4) carrying the machine frame (2), where the crawler track units (6) comprise a chain (12) which continuously revolves around at least one guide wheel (8) and at least one drive wheel (10), as well as several track rollers (14) which roll on the chain (12) and carry the machine frame (2), where the drive wheel (10) or preferably the guide wheel (8) is provided with an adjustment device (18), which enables the reciprocal spacing of the axles (20,22) of the drive wheel and guide wheel (8,10) to be adjusted for adaptation to a current lengthening of the chain (12), and where in addition to the adjustment device (18), a spring element (24) is provided which allows, using the adjusted spacing as a basis, a shortening of the spacing between the axles (20,22) of the drive wheel and guide wheel (8,10) against the spring force in the event of an operation-related increase of the chain tension to prevent any tension peaks in the chain (12), it is provided that the adjustment device (18) comprises a piston-cylinder unit (28) with a piston (30) to which a preferably hydraulic operating pressure can be applied in order to generate a predetermined force of the piston (30), and that, upon reaching the predetermined chain tension, a locking device (34) locks the end position of the piston (30) of the piston-cylinder unit (28) reached under the operating pressure applied.

Claims

1. Road construction machine, with

a machine frame, and

a chassis with a plurality of crawler track units, said chassis carrying the machine frame, where

the crawler track units comprise a chain which continuously revolves around at least one guide wheel and at least one drive wheel, as well as a plurality of track rollers which roll on the chain and carry the machine frame, where

an adjustment device acts on the drive wheel or on the guide wheel, enabling a reciprocal spacing of axles of the drive wheel and guide wheel to be adjusted for adaptation to a current lengthening of the chain, and where

in addition to the adjustment device, a spring element is provided which allows, using the adjusted spacing as a basis, a shortening of the spacing between the axles of the drive wheel and guide wheel against the spring force in the event of an operation-related increase of the chain tension to prevent any tension peaks in the chain,

characterized in that

the adjustment device comprises a piston-cylinder unit with a piston to which a hydraulic operating pressure can be applied in order to generate a predetermined force of the piston, and

that, upon reaching a predetermined chain tension, a locking device locks an end position of the piston of the piston-cylinder unit reached under the operating pressure applied.

3. Device in accordance with claim 1, characterized in that the locking device locks the end position of the piston of the piston-cylinder unit reached under the operating pressure applied upon reaching a counterforce between the axles of the drive wheel and guide wheel which essentially equals the force of the piston, or after a predetermined lapse of time of action of the adjustment device, or after reaching a predetermined slack in the upper strand of the chain.

4. Device in accordance with claim 1, characterized in that the spring element is arranged in series between the piston of the piston-cylinder unit and the axle of the drive wheel or guide wheel in a prestressed fashion.

5. Device in accordance with claim 1, characterized in that the same amount of operating pressure is applied to the adjustment devices of all crawler track units.

6. Device in accordance with claim 1, characterized in that the adjustment devices of all crawler track units are each connected to an own pressure accumulator.

7. Device in accordance with claim 1, characterized in that the piston-cylinder units of the adjustment devices of all crawler track units are interconnected.

8. Device in accordance with claim 7, characterized in that the piston-cylinder units of the adjustment devices of all crawler track units, are connected in parallel and are connected to a common pressure accumulator.

9. Device in accordance with claim 1, characterized in that a central pressure-limiting valve provides the operating pressure for the piston-cylinder unit of the adjustment devices of all crawler track units for adjustment of the desired chain tension.

2. Crawler track unit of a road construction machine, with a machine frame and a chassis with a plurality of crawler track units, said chassis carrying the machine frame, where

the crawler track units comprise a chain which continuously revolves around at least one guide wheel and at least one drive wheel, as well as a plurality of track rollers which roll on the chain and carry the machine frame, where

an adjustment device acts on the drive wheel or on the guide wheel, enabling a reciprocal spacing of the axles of the drive wheel and guide wheel to be adjusted for adaptation to a current lengthening of the chain, and where

in addition to the adjustment device, a spring element is provided which allows, using the adjusted spacing as a basis, a shortening of the spacing between the axles of the drive wheel and guide wheel against the spring force in the event of an operation-related increase of the chain tension to prevent any tension peaks in the chain,

characterized in that

the adjustment device comprises a piston-cylinder unit with a piston to which a hydraulic operating pressure can be applied in order to generate a predetermined force of the piston, and

that, upon reaching a predetermined chain tension, a locking device locks an end position of the piston of the piston-cylinder unit reached under the operating pressure applied.

10. Method for tensioning a chain of a crawler track unit of a road construction machine with a plurality of crawler track units, where said chain continuously revolves around at least one guide wheel and at least one drive wheel, the method including

adjustment of a spacing between axles of the drive wheel and guide wheel for adaptation to a current length of the chain, and

dynamic limitation of operation-related tension peaks of the chain by a spring element acting between the axles of the drive wheel and guide wheel, characterized by

adjusting the axle spacing between the axles of the drive wheel and guide wheel, prior to an operating stage, by applying a hydraulic operating pressure to a piston-cylinder unit to generate a predetermined force of the piston of the piston-cylinder unit, which increases the axle spacing, and

locking a position of the piston of the piston-cylinder unit upon reaching a predetermined chain tension.

11. Method in accordance with claim 10, characterized by locking the position of the piston of the piston-cylinder unit upon reaching a counterforce between the axles of the drive wheel and guide wheel which results from a predetermined chain tension and which essentially equals the force of the piston, or after action by the piston force of the piston over a predetermined time lapse, or upon reaching a predetermined slack in the upper strand of the chain.

12. Method in accordance with claim 10, characterized in that the same amount of operating pressure is applied to the piston-cylinder units of all crawler track units.

13. Method in accordance with claim 10, characterized in that the piston-cylinder units are interconnected for the purpose of adjusting the same amount of chain tension in all crawler track units.

14. Method in accordance with claim 13, characterized in that the piston-cylinder units, are connected in parallel and are connected to a common pressure accumulator for the purpose of maintaining a same amount of operating pressure.

15. Method in accordance with claim 10, characterized in that the piston-cylinder units of all crawler track units are supplied, prior to locking the end position of the piston, with the operating pressure via a central pressure-limiting valve.

16. A road construction machine, comprising:

a machine frame;

a plurality of crawler track units supporting the machine frame, each crawler track unit including;

a guide wheel having a guide wheel axis;

a drive wheel having a drive wheel axis;

a continuous chain extending around the guide wheel and the drive wheel;

a plurality of track rollers which roll on the chain;

an adjustment device including a piston-cylinder unit, the piston-cylinder unit including a piston to which a hydraulic operating pressure can be applied to generate a piston force acting on at least one of the guide wheel and the drive wheel to adjust an axis spacing between the guide wheel axis and the drive wheel axis; and

a spring acting on at least one of the guide wheel and the drive wheel, the spring allowing a shortening of the axis spacing in the event of an operation-related increase of chain tension to reduce any tension peaks in the chain;

a hydraulic pressure source;

a hydraulic supply line communicating the hydraulic pressure source to at least one of the piston-cylinder units; and

a locking valve disposed in the hydraulic supply line between the hydraulic pressure source and the at least one of the piston-cylinder units, the locking valve having an open position allowing hydraulic operating pressure to be applied to the at least one of the piston-cylinder units, and a closed position locking the piston of the at least one piston-cylinder unit in position relative to the cylinder under the applied hydraulic operating pressure.

17. The road construction machine of claim 16, further comprising:

a sensor operatively associated with the piston of the at least one piston-cylinder unit to detect when the piston comes to a standstill relative to the cylinder after application of hydraulic operating pressure to the piston; and

a controller operatively associated with the locking valve and the sensor, the controller operable to move the locking valve to its closed position after detection that the piston is at standstill.

18. The road construction machine of claim 16, further comprising:

a controller operably associated with the locking valve, the controller operable to move the locking valve to its closed position after a predetermined lapse of time after the application of hydraulic operating pressure to the piston of the at least one piston cylinder unit.

19. The road construction machine of claim 16, further comprising:

a distance sensor operatively associated with the chain for detecting slack in an upper strand of the chain; and

a controller operatively associated with the locking valve and the sensor, the controller operable to move the locking valve to its closed position after detection of a predetermined slack in the upper strand of the chain.

20. The road construction machine of claim 16, wherein:

the spring is prestressed and is arranged in series between the piston of the piston-cylinder unit and either the guide wheel axis or the drive wheel axis.

21. The road construction machine of claim 16, wherein:

the hydraulic supply line is communicated with the piston-cylinder units of all of the crawler track units so that an equal hydraulic operating pressure is applied to all of the piston-cylinder units.

22. The road construction machine of claim 16, further comprising:

a pressure accumulator communicated with at least one of the piston-cylinder units.

23. The road construction machine of claim 22, wherein:

the piston-cylinder units of all of the crawler track units are hydraulically connected together in parallel; and

the pressure accumulator is a common pressure accumulator communicated with all of the piston-cylinder units.

24. The road construction machine of claim 16, further comprising:

a central pressure-limiting valve communicated with the piston-cylinder units of all of the crawler track units.