Auxiliary flow valve system and method for managing load flow requirements for auxiliary functions on a tractor hydraulic system

Abstract

A system and method for managing hydraulic fluid load flow requirements for a tractor having a single pump hydraulic system. The system and method controls an implement hydraulic system and an auxiliary implement hydraulic system using a single hydraulic pump. The auxiliary flow valve system and method of the present disclosure gives precedence to the auxiliary functions so as to maintain full function of the auxiliary device. It also may supply a reduced flow, less than the maximum available from the system hydraulic pump to the auxiliary device. The remaining flow is available to the implement hydraulic system, with full flow being available to the implement when no auxiliary function is used. It also provides the ability to use a closed center valve in a load sensing system by bleeding flow pressure from the auxiliary hydraulic system.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims the priority of U.S. Provisional Patent Application No. 61 / 564,690 filed Nov. 29, 2011, herein incorporated by reference in its entirety for all purposes.FIELD OF THE INVENTION[0002]The present invention relates to land vehicle hydraulic systems generally and more specifically to pipelayer hydraulic assemblies mounted to track-type tractors.BACKGROUND OF THE INVENTION[0003]Hydraulic track-type pipelayers consist of a track-type crawler tractor with a pipelayer draw works structure mounted to it, along with the associated hydraulic hook and boom winches, the winch hydraulic-controls, and all the necessary rigging (per ISO 8813=mechanism to position the boom and hook). The track-type crawler tractor provides the power to drive the hydraulic winches, and any other hydraulic system fitted or used to control the crawler tractor.[0004]The pipelayer (implement) hydraulic system can be driven either directly with a dedicate...

AI Technical Summary

Benefits of technology

The auxiliary flow valve system and method described in this patent eliminate the need for additional pump drives in tight tractor engine compartments, making it easier to install. This system provides flexibility for installation in tight spaces over traditional dedicated auxiliary hydraulic pump systems.

Problems solved by technology

Due to this fact, when the pipelayer implement is connected to the tractor implement system in parallel, either the tractor implement system or the pipelayer system could be impaired when used simultaneously.

This is because the fluid directed to the path of least resistance could leave the other system with insufficient hydraulic pressure to adequately operate that system.

The same is not true, however, for essential hydraulic operations such as the tractor steering system and certain other auxiliary hydraulic systems.

In a single pump system, the steering function could be severely compromised unless it is given precedence over the other tractor implement functions.

With a pipelayer connected directly to a single-pump system which also services the steering function, the steering of the tractor could be drastically impaired if a load placed by the pipelayer implement consumes hydraulic flow, leaving insufficient flow for the steering function.

In this example, the majority of hydraulic fluid would flow through the pipelayer's hook circuit, leaving significantly less, and potentially insufficient, flow for the steering function.

This is an extremely undesirable situation.

For this type of reason, single pump differential steering systems have not been successfully implemented on tractors including implements such as pipelayers, and therefore pipelayers have been primarily used on crawler tractors with mechanical steering clutches.

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