Axle locking cylinder structure for heavy construction equipment

Abstract

An axle locking cylinder structure is provided. The axle locking cylinder includes 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.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a circuit diagram of a conventional axle locking cylinder;

FIG. 2 is a partially cross-sectional view illustrating the axle locking cylinder shown in FIG. 1;

FIG. 3 is a partially cross-sectional view illustrating an axle locking cylinder structure according to an embodiment of the present invention; and

FIG. 4 is a circuit diagram of the axle locking cylinder shown in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and thus the present invention is not limited thereto.

FIG. 3 is a partially cross-sectional view illustrating an axle locking cylinder structure according to an embodiment of the present invention, and FIG. 4 is a circuit diagram of the axle locking cylinder shown in FIG. 3.

The axle locking cylinder structure according to this embodiment includes, as shown in FIGS. 3 and 4, a locking cylinder 10 connected to a supply flow path 1 which communicates with a main hydraulic pump (not shown), and a return fluid path 2 which communicates with a pressurized reservoir (not shown), the locking cylinder 10 supplied with a hydraulic fluid through the supply flow path 1; a cylinder rod 3 slidably moved in the locking cylinder 10 by the pressure of the hydraulic fluid supplied to the locking cylinder 10; and a pilot valve 11 installed between the supply flow path 1 communicating with the main hydraulic pump and the flow path 13 communicating with the cylinder chamber 4 in the locking cylinder 10.

The axle locking cylinder structure for heavy construction equipment according to this embodiment includes a first pilot flow path 12 fed with the hydraulic fluid through the supply flow path 1 to drain a pilot pressure; a poppet valve 14 moved up and down by the pilot pressure to selective open and close a pilot flow path 13 connected to the cylinder chamber 4, the poppet valve 14 having a poppet stepped portion 19 extending from a poppet seat portion 14 towards a front end thereof and having a diameter smaller than that of the pilot flow path 13; a pressurized chamber 15 formed between the poppet valve 14 and the pilot flow path 13; a valve spring 16 resiliently supporting the poppet valve 14 downward to close the pilot flow path 13; a second pilot flow path 17 feeding the hydraulic fluid drained from the cylinder chamber 4 to the return flow path 2 when the pilot flow path 13 is opened; a branched flow path 21 formed between the cylinder chamber 4 and the supply flow path 1 and connected in parallel with the pilot valve 11 to supply the hydraulic fluid to the cylinder chamber 4 when the cylinder rod is expanded; and an adjusting plug 18 coupled to an upper portion of the locking cylinder 10 for adjusting the resilient force of the valve spring 16.

A check valve 20 is installed to one side of the branched flow path 21.

In the axle locking cylinder according to the present invention, the check valve 20 is fed with a certain pilot pressure through a third pilot flow path 23 which communicates with the pressurized chamber 15, and has a valve plunger 22 for selectively opening and closing the branched flow path 21 by using the pilot pressure.

The operation of the axle locking cylinder structure for the heavy construction equipment according to the present invention will now be described.

When an operator manipulates the axle locking, the certain hydraulic fluid is fed to the pilot valve 11 through the first pilot flow path 12, so that the poppet valve 14 closes the pilot flow path 13 to maintain the axle locking state.

In particular, when the axle locking is released in order to move the equipment after completing the work, the axle locking cylinder is fed with the pilot pressure through the second pilot flow path 17. The pilot pressure serves as a gauge pressure of the poppet valve 14 to push up the poppet seat portion 14a from the pilot flow path 13.

In this instance, since the poppet stepped portion 19 delays the open time of the pilot path 13 by a certain opening region Δd in the pilot flow path 13, the highly-pressurized hydraulic fluid is steadily drained from the cylinder chamber 4. Consequently, the operator can manipulate the equipment stably, without shocking the operator due to the sudden drain of the hydraulic fluid from the locking cylinder 10.

This is because the poppet stepped portion 19 serves as an orifice function when the hydraulic fluid passes through the opening region Δd when the pilot flow path 13 is opened. It means to prevent the shock from being applied to the operator when the high pressure is shifted to a low pressure in the locking cylinder 10.

Also, when the cylinder rod 3 is expanded, the valve plunger 22 install in the branched flow path 21 is moved by the pilot pressure passing through the third pilot flow path 23, thereby opening the check valve 20. Consequently, since the more flow rate is supplied to the cylinder chamber 4, the cylinder rod 3 is quickly expanded.

With the above description, according to the axle locking cylinder structure for the heavy construction equipment according to the present invention, the operator can manipulate the equipment without getting the shock, when the high pressure is shifted to the low pressure in the locking cylinder. When the cylinder rod is expanded, a sufficient flow rate is supplied to the locking cylinder, so that the cylinder rod is quickly expanded.

Although preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

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

2. The axle locking cylinder structure as claimed in claim 1, further comprising a check valve installed to one side of the branched flow path.

3. The axle locking cylinder structure as claimed in claim 2, 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.