Cross-Reference to Related Appllcation(s)

This application is being filed on July 21, 2014, as a PCT International Patent application and claims priority to Indian Patent Application Serial No.

886/KOL/2013 filed on July 24, 2013, the disclosure of which is incorporated herein by reference in its entirely.

Technical Field

The present disclosure provides a compact high-output piston assembly that includes multiple pistons. Background

Hydraulic pistons are used for mechanical actuation in many applications. The hydraulic pistons are arranged such that extending and retracting a piston rod connected to pistons housed in a cylinder body causes a desired mechanical action.

Pressurized hydraulic fluid is directed into and out of the cylinder thereby causing the piston rod to extend and retract Improved high performance pistons are desirable.

Summary

A hydraulic piston is provided that includes an improved modular piston rod and piston assembly that facilitates assembly and disassembly thereof. Also provided are improved methods of assembling and disassembly of a piston rod. Brief Description of the Figures

FIG. 1 is an isometric view of a hydraulic cylinder according to an embodiment of the present disclosure;

FIG. 2 is a top elevation view of the hydraulic cylinder of FIG. 1 ;

FIG. 3 is a cross-sectional view of the hydraulic cylinder of FIG. 1;

FIG.4 is an enlarged view of a portion of FIG. 3;

FIG. 5 is a cross-sectional view of an alternative embodiment of a hydraulic cylinder according to the present disclosure;

FIG. 6 is a cross-sectional view of an alternative embodiment of a hydraulic cylinder according to the present disclosure; FIG. 7 is a cross-sectional view of an alternative embodiment of a hydraulic cylinder according to the present disclosure; and

FIG. 8 is a cross-sectional view of an alternative embodiment of a hydraulic cylinder according to the present disclosure.

Detailed Description

Referring to the FIGS. 1-4, a first embodiment of a hydraulic piston according to the present disclosure is described below in further detail. In the depicted embodiment, the hydraulic cylinder 10 includes a cylinder body 12, a first intermediate head assembly 14, and a second intermediate head assembly 16. In the depicted embodiment, each intermediate head assembly 14, 16 is configured to enable hydraulic fluid to

simultaneously flow into and out of the cylinder body through hydraulic ports 18, 20, 22, 24 on the intermediate head assemblies 14, 16. In the depicted embodiment the hydraulic cylinder 10 further includes a first head cap 26 located at a first end 28 of the cylinder body 12 and a second head cap 30 located at a second end 32 of the cylinder body 12. Each of the first and second head caps 26, 30 are configured to enable hydraulic fluid to flow into and out of the cylinder body. It should be appreciated that many other alternative hydraulic piston configurations are possible.

In the depicted embodiment the hydraulic piston includes a piston rod 34 that extends coaxially into the cylinder body 12, which in the depicted embodiment is generally cylindrical. Pistons 36, 38, 40 are supported on the piston rod 34 and slide within the cylinder body 12 in response to hydraulic pressure due to the flow of hydraulic fluid into and out of the heads 26, 14, 16 and 30. The pistons in the depicted embodiment are cylindrical member that interface with the inside surface of the cylinder body 12. In the depicted embodiment end piston 36 is positioned between the first head cap 26 and the first intermediate head assembly 14, end piston 40 is positioned between the second head cap 30 and the second intermediate head assembly 16, and intermediate piston 38 is positioned between the first intermediate head assembly 14 and the second intermediate head assembly 16. It should be appreciated that many other alternative hydraulic piston configurations are possible.

During normal operations to move the piston to the left, hydraulic fluid would be allowed to escape through the first head cap 26 and be delivered to the hydraulic cylinder through the second head cap 30. Simultaneously, ports 18 and 22 of the intermediate head assemblies 14, 16 would deliver hydraulic fluid, and ports 20 and 24 would allow for the escape of hydraulic fluid from the cylinder body 12. Conversely, to move the piston to the right, hydraulic fluid would be allowed to escape through the second head cap 30 and be delivered through the first head cap 26. Simultaneously, ports 20 and 24 of the intermediate head assemblies 14, 16 would deliver hydraulic fluid, and ports 18 and 22 would allow for the escape of hydraulic fluid from the cylinder body 12. It should be appreciated that many other alternative hydraulic piston configurations and modes of operation are possible (for example, the piston can be moved to the left by delivering fluid to the cylinder body only via the second head cap 30).

In the depicted embodiment, end piston 36 is integrally formed on the piston rod

34. On the other hand, intermediate piston 38 and end piston 40 are modular in that they are separate and distinct components that can be connected to the piston rod after the piston rod is formed. In the depicted embodiment intermediate piston 38 and end piston 40 have the same structure. Both include base portions 50, 52 that include end recesses in end faces that mate interchangeably with either an end portion 42, 54, 56 of a sleeve 44, 46 or the shoulder 48 of the piston rod 34. In the depicted embodiment the sleeves 44, 46 extended over a neck down portion 58 of the piston rod 34 (a portion of the piston rod that has a smaller diameter). In the depicted embodiment the first portion 72 of the piston rod has a diameter Dl and the necked down portion 58 has a diameter D2, which is smaller thanDl. The sleeves 44, 46 are compressed, thereby locking the pistons 38, 40 in place such that they cannot slide laterally relative to the piston rod 34.

In the depicted embodiment the hydraulic cylinder 10 includes a preload assembly that is configured to apply tension to the piston rod 34 and compression to the pistons 38, 40 that are not internally formed on the piston rod 34. In the depicted embodiment, sleeve 44 (intermediate sleeve) extends from piston 38 past the second intermediate head assembly 16 to abut piston 40. Sleeve 46 (end sleeve) extends from piston 40 based to the second end head 30 located outside of the cylinder body 12. The end 60 of the sleeve 46 that extends out of the cylinder body 12 abuts an end plate 62. One or more tension members (e.g., bolts) extend through the end plate 62 and connect to the end of the piston rod 34 to simultaneously apply tension to the piston rod 34 and compression to the sleeves 44, 46 and pistons 38 and 40.

In the depicted embodiment the tension member of the preloading assembly includes a multi-jackbolt tensioner type boh. The multi-jackbolt is configured such that the bolt applies tension (tightens) by torqueing multiple smaller bolts 64 located at the bolt head 70 that press against a washer 68 and thereby together pull on the larger center bolt 66 (see FIG.4). It should be appreciated that many alternative tensioning members exist including, for example, standard type bolts. In the depicted embodiment the cumulative length of the base portions of pistons 38, 40 and sleeves 44 and 46 is greater than the length of the necked down portion 58 of the piston rod 34, thereby resulting in a gap 74 between the end face 76 of the piston rod 34 and the end face 78 of the end plate 62. The gap allows for any slack to be taken up the preload assembly facilitates a tension force being generated in the piston rod and simultaneously a compression being generated in the sleeves 44, 46. This preloading improves the fatigue characteristics of these components thereby lengthening the working life of the hydraulic cylinder 10 while also facilitating the ease of assembly of the hydraulic cylinder 10.

The depicted configuration provides a system that can hold up to high forces as it minimizes stress concentration within the piston rod and piston assembly and also reduces the alternating stress thereby increase the fatigue life of the assembly. It also facilitates quick and easy assembly and disassembly since the pistons which have a diameter D3 that is almost the same as the internal diameter of the cylinder body and greater man the internal diameter D4 of the head assemblies 26, 14, 16, 30 are modular with respect to the piston rod 34.

In the depicted embodiment a method of assembling a hydraulic piston includes the steps of: positioning a piston 38 within a center section 80 of the cylinder body12, the center section 80 of the cylinder body includes a first end 82 and second end 84; mounting a first head assembly 14 to the first end 82 of the center section 80 of the cylinder body 12; mounting a second head assembly 16 to the second end 84 of the center section of the cylinder body; sliding a piston rod 34 through the center section of the cylinder body 12 and through the piston 38; sliding a sleeve 44 over a portion of the piston rod 34; and applying a compression force onto the sleeve. In the depicted embodiment the step of positioning the piston 38 in the center section 80 occurs before both of the first and second head assemblies 14, 16 are attached to the center section 80. In the depicted embodiment the other above-described steps can occur in any relative order.

Referring to FIG. 5, an alternative embodiment of a piston rod configuration is shown. The depicted piston and piston rod assembly 100 includes three pistons 102, 104 and 106 and four sleeves 108, 110, 112 and 114. Each one of the pistons is modular with respect to the piston rod 116 (the pistons are not integral with the piston rod 116). At each end of the piston rod 116 are tensioning assemblies that include tensioning members extending through end plates 118, 120 into end portions of the piston rod 116.

Referring to FIG. 6, an alternative embodiment of a piston rod configuration is shown. In the depicted piston and piston rod assembly 122, the piston rod 124 only extends partially through the cylinder body (not shown). The right portion of the piston rod assembly includes long bolts 126 that extend from an end plate 128 to an end portion of the piston rod 124. The piston rod assembly 122 includes three pistons 130, 132 and 134. Piston 130 is integral with the piston rod 124, and pistons 132 and 134 are modular with respect to the piston rod 124. A plurality of sleeves 136 extend around the bolts 126 and act as spacer collars between the pistons and end plate. The sleeves 136 are arranged to be under compression when the bolts 126 are tightened.

Referring to FIG. 7, an alternative embodiment of a piston rod configuration is shown. The depicted piston and piston rod assembly 138 is similar to the piston rod assembly 122. The primary difference is that the modular pistons 140 and 142 nest into each other and include integrally formed sleeve portions 144 and 146.

Referring to FIG. 8, an alternative embodiment of a piston rod configuration is shown. The depicted piston and piston rod assembly 148 is similar to the piston rod assembly 122. The primary difference is that the integrally formed piston 150 and piston rod 152 is the center piston located between two modular pistons 154 and 156. Sleeve 155 acts as a spacer between the end plates 158, 160 and the end pistons 154 and 156.

The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.