WO2018145167A1

WO2018145167A1 - Sealing assembly for a hydraulic cylinder

Info

Publication number: WO2018145167A1
Application number: PCT/AU2018/050105
Authority: WO
Inventors: Peter Parks
Original assignee: Parks Industries Pty Ltd
Priority date: 2017-02-09
Filing date: 2018-02-09
Publication date: 2018-08-16

Abstract

The present disclosure provides a sealing assembly for a hydraulic cylinder system that comprises two hydraulic seals disposed within a wall portion of a hydraulic cylinder. The seals are pressurised via a conduit in a wall portion of the cylinder and provide an additional insulation from external contamination that can damage the hydraulic system.

Description

SEALING ASSEMBLY FOR A HYDRAULIC CYLINDER Field of the Invention

The present invention relates to a system for sealing a hydraulic cylinder. In particular the present invention relates to a system for sealing a hydraulic cylinder- piston-rod system suitable for use in demanding

environments such as the mining industry.

Background of the Invention

Hydraulic cylinder and piston arrangements are commonly used for machinery in demanding environments, such as in the mining industry. For example, iron ore stackers, reclaimers and ship loaders use large hydraulic cylinders- piston systems for performing demanding lifting

operations. The cylinders-piston systems generally operate "around the clock" and substantial costs are incurred for any down time.

Unfortunately, such hydraulic cylinder-piston systems fail frequently in such demanding environments. For example, hydraulic cylinder-piston systems used in the mining industry fail as ore dust wears oil sealing surfaces of the hydraulic cylinder-piston systems. The hydraulic cylinder-piston systems are expensive to replace or repair due to size, location and SHE (Safety, Health &

Environment) requirements. Further, any repair or

replacement is associated with downtime of the machinery, which results significant losses in productivity and associated costs.

Any improvements to life expectancy of such hydraulic cylinder-piston system consequently results in an economic advantage .

Summary of the Invention

In a first aspect of the present invention there is provided a hydraulic assembly comprising: a hydraulic cylinder and piston assembly,

comprising : a first hydraulic cylinder portion; a piston and rod assembly moveable within the first hydraulic cylinder portion; a pressure seal used to retain a pressurised fluid in the first hydraulic cylinder portion when the hydraulic cylinder and piston assembly is used;

the hydraulic assembly further comprising: a sealing assembly for the hydraulic cylinder and piston assembly, the sealing assembly

comprising : a second cylindrical body portion extending from an end of the first hydraulic cylinder portion; at least two hydraulic seals disposed within a wall portion of the second cylindrical body portion and surrounding the rod; and a conduit through a wall portion of the second cylindrical body portion, the conduit being positioned between two adjacent ones of the at least two hydraulic seals and being arranged for throughput of a fluid; wherein the two adjacent hydraulic seals surround and seal the rod and, when the fluid has been directed through the conduit into a region between the two adjacent hydraulic seals, the wall portion of the second cylindrical body portion and the rod, the region is pressurised. Embodiment of the present invention provide the practical advantage that the at least two hydraulic seals

significantly extend the lifetime of the pressure seal as the at least two hydraulic seals largely isolate the pressure seal from dust that is especially in a mining environment a significant problem for conventional

hydraulic assemblies not having the at least two hydraulic seals .

The second cylindrical body portion may be fastened to the end of the first hydraulic cylinder portion using a fastening mechanism. Alternatively, the first hydraulic cylinder portion and the second cylindrical body portion may be integrally formed.

The hydraulic assembly typically is suitable for use in a mining environment. The hydraulic cylinder and piston assembly may comprise cushions and wear bands that are used to guide the rod and reduce wear. The hydraulic cylinder and piston assembly may further comprise a buffer seal positioned in the proximity of an opening of the hydraulic cylinder.

The hydraulic assembly may comprise a further conduit through a wall portion of the second cylindrical body portion and that is positioned between the two adjacent ones of the hydraulic seals and allows draining of fluid from the region between the two adjacent ones of the at least two hydraulic seals. This feature provides the practical advantage that, when the outermost of the hydraulic seal is worn for example because of dust that accumulates on the rod when the hydraulic cylinder

arrangement is used for example in a mining environment, the fluid between the two hydraulic seals may simply be drained and the system can continue operation (when the pressure seal is still functional) without loss of hydraulic fluid, which would be an environmental hazard et . In contrast, a known hydraulic cylinder and piston assembly does not have the at least two hydraulic seals and consequently the pressure seal would wear much quicker because of dust accumulated on the rod during operation. If the pressure seal is worn, oil will be expressed between the cylinder and rod of the known hydraulic assembly, which is an environmental hazard and causes expensive downtime.

Further, the hydraulic cylinder arrangement may comprise a pressure monitor for monitoring the pressure of the fluid between the at least two adjacent seals, which allows monitoring the wear of the hydraulic seals by monitoring the pressure of the fluid between the at least two

adjacent hydraulic seals.

In a second aspect of the present invention there is provided a method of operating the hydraulic assembly in accordance with the first aspect, comprising the step of: pressurising the region between the at least two adjacent ones of the hydraulic seals by directing the fluid into the region; wherein a drop in pressure within the region and/or an outflow of the fluid is indicative of a wear state of the two adjacent ones of the at least two hydraulic seals.

The method may comprise monitoring the pressure within the region and/or monitoring an outflow of the fluid out of the region. Further, the method may comprise monitoring the pressure within the region and/or monitoring an outflow of the fluid out of the region.

In a third aspect of the present invention there is provided a sealing assembly for a hydraulic cylinder system having a first hydraulic cylinder portion, the sealing assembly comprising: a second cylindrical body portion mountable to a first hydraulic cylinder portion; at least two hydraulic seals disposed within a wall portion of the second cylindrical body portion and

arranged to receive a rod; and a conduit through a wall portion of the second cylindrical body portion, the conduit being positioned between two adjacent ones of the at least two hydraulic seals and being arranged for throughput of a fluid; wherein, when the rod is positioned within the second cylindrical body portion in a manner such that the two adjacent hydraulic seals surround and seal the rod and the fluid has been directed through the conduit into a region between the two adjacent one of the at least two hydraulic seals, the wall portion of the second

cylindrical body portion and the rod, the region is pressurised.

In embodiments, the sealing assembly comprises a fastening mechanism for fastening the sealing assembly to an end the first hydraulic cylinder portion of the hydraulic cylinder and piston assembly, wherein the sealing assembly is arranged such that, when the sealing assembly is fastened to the end of the first hydraulic cylinder portion, the two adjacent ones of the at least two hydraulic seals surround the rod.

In some embodiments, the sealing assembly comprises a further conduit through a wall portion of the second cylindrical body portion and that is positioned between the two hydraulic seals and allows draining of fluid from the region between the two adjacent ones of the at least two hydraulic seals. In accordance with the fourth aspect, the present

invention provides hydraulic assembly comprising: a hydraulic cylinder; a piston and rod assembly moveable within the hydraulic cylinder; at least two hydraulic seals disposed within a wall portion of the hydraulic cylinder and arranged to receive the rod; and a conduit through a wall portion of the hydraulic cylinder, the conduit being positioned between two adjacent ones of the at least two hydraulic seals and being arranged for throughput of a fluid; wherein, when the rod is positioned within the second cylindrical body portion in a manner such that the two adjacent hydraulic seals surround and seal the rod and the fluid has been directed through the conduit into a region between the two adjacent hydraulic seals, the wall portion of the hydraulic cylinder and the rod, the region is pressurised. Advantages of embodiments include the capability of avoiding or trapping contaminants before they reach the primary high pressure seals and compromise the operation of the hydraulic cylinder piston system.

Furthermore, embodiments of the invention to retrofit existing hydraulic systems to provide the advantages mentioned above and therefore extend their lifetime.

The hydraulic assembly typically is suitable for use in a mining environment.

The hydraulic assembly may comprise a further conduit through a wall portion of the second cylindrical body portion and that is positioned between the two adjacent ones of the hydraulic seals and allows draining of fluid from the region between the two adjacent ones of the at least two hydraulic seals. Brief Description of the Drawings

Features and advantages of the present invention will become apparent from the following description of

embodiments thereof, by way of example only, with

reference to the accompanying drawings in which:

Figures 1 and 3 show schematic representations of a hydraulic assembly;

Figures 2 and 4 show sectional views of hydraulic

assemblies in accordance with the schematic

representations of Figures 1 and 3, respectively; and

Figure 5 shows a schematic diagram of a hydraulic system used with a hydraulic cylinder and sealing assembly in accordance with embodiments.

Detailed Description of Embodiments Embodiments of the present disclosure relate to a sealing assembly for a hydraulic cylinder that reduces

contamination of a hydraulic cylinder system.

Hydraulic systems are frequently used in demanding environments, such as at mine sites. High pressure seals are used in such systems and allow high oil pressures inside the hydraulic cylinder. However, abrasive

contamination resulting from ore dust and the like causes wear of hydraulic seals and frequently leads to system failure. Wiper elements are used to reduce likelihood that such contamination reaches the high pressure seals where it has a detrimental effect on the wear state of the high pressure seal. The rod is lubricated to facilitate movement of the rod through the high pressure seal and the wiper. The wiper has a lip, which is designed to wipe off contamination from the rod when the rod moves into the cylinder (seal gland design) .

In demanding environments, after a given amount of

operating hours, the integrity of the wiper can be

compromised. External contaminants can then reach the high pressure seal and eventually damage that seal, causing high pressure oil spills and forcing the shut-down of the equipment .

Referring initially to Figure 1, there is shown a

schematic representation of a hydraulic system 100 with a sealing assembly 102 in accordance with embodiments. The system comprises a first hydraulic cylinder portion 104 that hosts a piston 106 and a rod 108. The sealing assembly also comprises a second cylindrical body portion 105, which is integrally formed with the first hydraulic cylinder portion 105. The first hydraulic cylinder portion 104 contains in use oil at a high pressure

(typically in the order of 5000 psi) . A series of cushions 110 and wear bands 112 are used to guide the rod 108 and reduce wear. In addition, a buffer seal 114 is positioned in the proximity of an opening of the cylinder to absorb sudden changes in oil pressure. A high pressure seal 116 is used to retain the pressurised oil inside the cylinder 104.

To improve the lifetime of system 100, and in particular that of the high pressure seal 116, the inventors have engineered the sealing assembly 102 comprising at least two additional hydraulic seals 118 and 120 that are disposed within a wall portion of first hydraulic cylinder portion 104. Seals 118 and 120 receive the rod 108, but are not subject to the same high oil pressure as seal 116. Instead, a region defined by the seals 118 and 120, the first hydraulic cylinder portion 104 and the rod 108 is pressurised separately using oil, which is introduced through conduit 122. This oil has a pressure in the order of 300 psi to 500 psi. The pressure is maintained largely constant, which allows seals 118 and 120 to be energised thereby maintaining a pre-determined sealing function on rod 108. A hydraulic arrangement (not shown in Figure 1) is used to maintain and monitor the pressure between the seals 118 and 120 to ensure that a predetermined pressure is maintained. A wiper element 124 is used at the aperture of cylinder 104 reduce contamination from particles entering through the rod 108 and affecting the seal 120.

As discussed above, wiper elements, such as the element 124, have a finite lifetime. During operation the element 124 does wear out and eventually allows contaminants, such as iron ore dust in the case of the mining environment, to reach the seal 120. These contaminants can damage seal 120 and cause an oil leakage. By using the sealing assembly 102, the oil spill caused by the contaminants does not force the shut-down of the equipment as the main high pressure seal 116 remains operational. The damage to the seal 120 causes ^ow-pressure' oil to leakage and can also be detected by a drop in pressure (the predetermined pressure cannot be maintained) . For minoring damage of the seal 120, oil pressure in the cavity between seals 118 and 120 can be maintained by acting on the oil supply connected to the conduit 122. Alternatively, the oil leakage can be stopped by acting on the hydraulic

arrangement that delivers the fluid to the conduit 122, for example by closing feeding valve such that the seals 118 and 120 are still lubricated, but the region between the seals 118 and 120 is no longer pressurised. The seal 118 would then still function as a wiper element. In any case, the sealing assembly 102 increases the overall lifetime of the system (in particular of the high pressure seal 116), which provides substantial advantages in terms of equipment down time and operating cost.

The second cylindrical body portion 105 also comprises a further conduit 126 through a wall portion of the

cylinder. The conduit 126 allows draining a portion of the oil from the region between seals 118 and 120 to check contamination level and estimate remaining lifetime of the sealing assembly.

Referring now to Figure 2, there is shown a sectional side view of a hydraulic cylinder system in accordance with embodiments of the present invention. The system of Figure 2 is an implementation of the schematic of Figure 1 and the same reference numerals are used to reference the features described above with reference to Figure 1.

Figure 2 does not show rod 108. In contrast to the

hydraulic cylinder system of Figure 1, the hydraulic cylinder system of Figure 2 comprises a second cylindrical body portion 155 that is bolted onto an end of a first hydraulic cylinder portion 152

Referring now to Figure 3, there is shown an alternative embodiment of a hydraulic system 200. The system 200 comprises a first hydraulic cylinder portion 204 and a detachable sealing assembly 202.

When the first hydraulic cylinder portion 204 and the detachable sealing assembly 202 are mounted together, the system 200 operates in a similar way to the hydraulic system described above with reference to Figure 1.

System 200 has an additional wiper element 226 that allows protecting high pressure filter 216 when the sealing assembly 202 is detached from the first hydraulic cylinder portion 204.

The first hydraulic cylinder portion 204 features a fastening mechanism 217a that enables connection to the sealing assembly 202 via fasteners 217b disposed on the second cylindrical body portion 205 of the sealing

assembly 202.

The sealing assembly 202 has two hydraulic seals 218 and 220 disposed within a wall portion of second cylindrical body portion 205 and arranged to receive the rod 208.

Second cylindrical body portion 205 has also two conduits 222 and 226 (only conduit 226 is shown, conduit 222 is located opposite conduit 226) extending through wall portions between the hydraulic seals 218 and 220 that in use operate in a similar way to the conduits 118 and 120 of Figure 1. The system of Figure 3 allows for replacement of sealing assembly 202 on site and therefore minimisation of the equipment down time. Another advantage is related to the possibility of retrofitting existing hydraulic systems with assembly 202 to extend their lifetime. Referring now to Figure 4, there is shown a sectional side view of a hydraulic cylinder system in accordance with embodiments. The system of Figure 4 is an implementation of the schematic of Figure 3 and the same reference numerals are used to reference the features described above with reference to Figure 1. Figure 3 does not show rod 208.

Referring now to Figure 5, there is shown a diagram of a hydraulic arrangement used to pressurise a sealing

assembly in accordance with embodiments.

Figure 5 illustrates a system 300 for pressurising the region between the seals 118 and 120 (shown in Figure 1, not shown in Figure 5) . A fluid conduit is coupled to the cylinder of the hydraulic cylinder and piston assembly at a cylinder retract manifold port 310.

A first cycle of the hydraulic cylinder and piston

assembly will energise the seals 118 and 120 with

hydraulic pressure. This pressure is determined by a pressure reducing valve 306 and maintained during every subsequent cycle of the hydraulic pump and assembly. This pressure is also maintained when the cylinder is static (not in operation) thereby preventing any ingress of contamination .

The pressure can be monitored using pressure gauge 304. A drop in pressure or oil leakage indicates wear of the hydraulic pressure seal 120. Ball valve 308 may then be de-energised (closed) , which reduces the pressure within the region between seals 118 and 120. However, the primary hydraulic seal of the cylinder/piston arrangement can continue operation, thereby given an even further extended life.

At any interval during the entire operation of this hydraulic cylinder, contamination of the oil can be monitoring by draining oil from a dedicated oil sampling port 312. This is done simply and without any SHE hazard.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are,

therefore, to be considered in all respects as

illustrative and not restrictive.

Claims

The Claims as defined in the invention are as follows:

1. A hydraulic assembly comprising: a hydraulic cylinder and piston assembly,

comprising : a first hydraulic cylinder portion; a piston and rod assembly moveable within the first hydraulic cylinder portion; and a pressure seal used to retain a pressurised fluid in the first hydraulic cylinder portion when the hydraulic cylinder and piston assembly is used;

comprising: a second cylindrical body portion extending from an end of the first hydraulic cylinder portion; at least two hydraulic seals disposed within a wall portion of the second cylindrical body portion and surrounding the rod; and a conduit through a wall portion of the second cylindrical body portion, the conduit being positioned between two adjacent ones of the at least two hydraulic seals and being arranged for throughput of a fluid; wherein the two adjacent hydraulic seals surround and seal the rod and, when the fluid has been directed through the conduit into a region between the two adjacent hydraulic seals, the wall portion of the second cylindrical body portion and the rod, the region is pressurised.

2. The hydraulic assembly of claim 1 wherein the second cylindrical body portion is fastened to the end of the first hydraulic cylinder portion using a fastening mechanism .

3. The hydraulic assembly of claim 1 wherein the first hydraulic cylinder portion and the second cylindrical body portion are integrally formed.

4. The hydraulic assembly of any one of the preceding claims wherein the hydraulic cylinder and piston assembly comprises cushions and wear bands that are used to guide the rod and reduce wear.

5. The hydraulic assembly of any one of the preceding claims further comprising a buffer seal positioned in the proximity of an opening of the hydraulic cylinder.

6. The hydraulic assembly of any one of the preceding claims comprising a further conduit through a wall portion of the second cylindrical body portion and that is

positioned between the two adjacent ones of the hydraulic seals and allows draining of fluid from the region between the two adjacent ones of the at least two hydraulic seals.

7. The hydraulic assembly of any one of the preceding claims wherein the hydraulic assembly is suitable for use in a mining environment.

8. The hydraulic assembly of any one of the preceding claims comprising a pressure monitor for monitoring the pressure of the fluid between the at least two adjacent seals .

9. A method of operating the hydraulic assembly of any one of the preceding claims, comprising the step of: pressurising the region by directing the fluid into the region; wherein a drop in pressure within the region and/or an outflow of the fluid is indicative of a wear state of at least one of the two adjacent ones of the at least two hydraulic seals.

10. The methods of claim 9 wherein the hydraulic

assembly is suitable for use in a mining environment and wherein the method comprises operating the hydraulic assembly in the mining environment.

11. The method of claim 9 or 10 comprising monitoring the pressure within the region and/or monitoring an outflow of the fluid out of the region.

12. The method of any one of claims 9 to 11 comprising monitoring the pressure within the region and/or

monitoring an outflow of the fluid out of the region.

13. A hydraulic assembly comprising: a hydraulic cylinder; a piston and rod assembly moveable within the hydraulic cylinder; at least two hydraulic seals disposed within a wall portion of the hydraulic cylinder and arranged to receive the rod; and a conduit through a wall portion of the hydraulic cylinder, the conduit being positioned between two adjacent ones of the at least two hydraulic seals and being arranged for throughput of a fluid; wherein, when the rod is positioned within the hydraulic cylinder in a manner such that the two adjacent hydraulic seals surround and seal the rod and the fluid has been directed through the conduit into a region between the two adjacent hydraulic seals, the wall portion of the hydraulic cylinder and the rod, the region is pressurised .