Axle locking cylinder structure for heavy construction equipment

• US 7,748,309 B2
• Filed: 05/25/2007
• Issued: 07/06/2010
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Volvo Construction Equipment Holding Sweden AB
• Original Assignee: Volvo Construction Equipment Holding Sweden AB
• Inventors: Kim, Jong In
• Primary Examiner(s): Lazo; Thomas E
• Application Number:
  US11/805,967
• Publication Number:
  US 20070295419A1
• Time in Patent Office: 1,138 Days
• Field of Search: 604/68, 914/43
• US Class Current: 91/443
• CPC Class Codes: E02F 9/2257 Vehicle levelling or suspension systems suspensions for vehicles in general B60G
• CPC Class Codes: E02F 9/226 Safety arrangements, e.g. hydraulic driven fans, preventing cavitation, leakage, overheating
• CPC Class Codes: Y10T 137/86493 Multi-way valve unit

Abstract

An axle locking cylinder structure is capable of enabling an operator of heavy construction equipment to stably carry out an axle locking operation since a sudden variation of the flow rate is prevented in the axle locking cylinder by draining a highly-pressurized flow rate slowly at the release of axle locking and supplying a flow rate quickly at the drive of axle locking. A highly-pressurized hydraulic fluid can be steadily drained from a cylinder chamber since an opening region between a poppet valve and a pilot flow path is enlarged so as to open the pilot flow path connected to the cylinder chamber during a relatively long time. A cylinder rod can be quickly expanded according to the manipulation of an axle locking switch by compensating a flow rate supplied to a cylinder chamber when the cylinder rod is expanded.

Claims

1. An axle locking cylinder structure for heavy construction equipment, including a locking cylinder connected to a supply flow path which communicates with a main hydraulic pump, and a return fluid path which communicates with a pressurized reservoir, the locking cylinder being supplied with a hydraulic fluid through the supply flow path;

a cylinder rod slidably moved in the locking cylinder by a pressure of the hydraulic fluid supplied to the locking cylinder; and

a pilot valve installed between the supply flow path communicating with the main hydraulic pump and the flow path communicating with the cylinder chamber in the locking cylinder;

the axle locking cylinder structure comprising;

a first pilot flow path fed with the hydraulic fluid through the supply flow path to drain a pilot pressure;

a poppet valve moved up and down by the pilot pressure to selective open and close a pilot flow path connected to the cylinder chamber, the poppet valve having a poppet stepped portion extending from a poppet seat portion towards a front end thereof and having a diameter smaller than that of the pilot flow path;

a pressurized chamber formed between the poppet valve and the pilot flow path;

a valve spring resiliently supporting the poppet valve downward to close the pilot flow path;

a second pilot flow path feeding the hydraulic fluid drained from the cylinder chamber to the return flow path when the pilot flow path is opened;

a branched flow path formed between the cylinder chamber and the supply flow path and connected in parallel with the pilot valve to supply the hydraulic fluid to the cylinder chamber when the cylinder rod is expanded; and

an adjusting plug coupled to an upper portion of the locking cylinder for adjusting the resilient force of the valve spring,

and further comprising a check valve installed to one side of the branched flow path, wherein the check valve is fed with a certain pilot pressure through a third pilot flow path which communicates with the pressurized chamber, and has a valve plunger for selectively opening and closing the branched flow path by using the pilot pressure.