Hydraulic cylinder piston rod protection system

A protection system for a hydraulic cylinder piston having a barrel and a piston rod reciprocating therein, the protection system comprising a piston rod shield which is fixed with respect to the piston rod in use to move with respect to the barrel to cover the piston rod when the piston rod is exposed from the barrel and wherein the piston rod shield comprises a non-metallic flexible material which substantially returns to shape after deformation.

FIELD OF THE INVENTION

This invention relates generally to a system for protecting piston rods of hydraulic cylinders of excavators, especially those of exposed backhoe bucket cylinders.

BACKGROUND OF THE INVENTION

Piston rods of hydraulic excavator backhoe bucket cylinders are prone to damage on account of their exposed position, especially during operations such as double benching.

A burred piston rod may damage the wiper and rod seal of the barrel cap and the resultant downtime and maintenance may be very costly, especially for large excavators.

Metal channel boxes have been used to protect piston rods, but which however are themselves prone to damage, requiring continual maintenance and replacement and may itself damage the piston rod if sufficiently deformed.

The present invention seeks to provide a way to overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative.

SUMMARY OF THE DISCLOSURE

There is provided herein a cylinder piston rod protection system, especially suited for protecting exposed backhoe bucket cylinders.

The system comprises a piston rod shield fixed with respect to a piston rod of the cylinder so as to move with respect to a barrel thereof and to protectively cover the piston rod when the piston rod is exposed from the barrel. The piston rod shield may be semi-cylindrical.

The piston rod shield comprises a non-metallic flexible material which may comprise high density plastic such as high-density polyethylene (HDPE).

Experimentation shows that even when struck by large falling rocks, the non-metallic flexible piston rod shield is able to deform and protect the smooth surface of the piston rods even if coming into contact with the piston rod. The flexible piston rod shield thereafter returns to shape to withstand repeated blows.

The system may comprise a guide having a guide channel through which a proximal end of the piston rod shield slides. The guide channel may conform closely to exterior and interior surfaces of the piston rod shield including to mould the piston rod shield back to shape when passing therethrough. Longitudinally extending flanges may extend adjacent the guide channel to bear across outer or inner surfaces of the flexible piston rod shield.

The system may further comprise a barrel shield which may similarly comprise non-metallic flexible material. The piston rod shield may slide over the barrel shield and an outer surface of the barrel shield may conform to an undersurface of the piston rod shield such that the piston rod shield slides closely over the barrel shield.

The barrel shield may comprise sufficient radius to allow for the reticulation of piston port hydraulic hosing thereunder. The system may comprise a shaft collar holding a mount which engages an undersurface of the barrel shield and wherein the barrel mount comprises apertures therethrough through which the piston port hydraulic hosing is able to pass.

In a preferred embodiment, a distal end of the flexible piston rod shield comprises a shock absorber to absorb shock at this more exposed portion of the piston rod.

The shock absorber preferably comprises a rubber of plastic insert which conforms closely to an undersurface of the piston port shield. A piston rod shaft collar may hold a mount which may adjacently engaged the rubber insert adjacently.

It should be noted that whereas the present protection system has been described primarily with reference to protecting piston rods of backhoe bucket cylinders the present protection system may have application for protecting other types of hydraulic cylinders.

According to one aspect, there is provided a protection system for a hydraulic cylinder piston having a barrel and a piston rod reciprocating therein, the protection system comprising a piston rod shield which is fixed with respect to the piston rod in use to move with respect to the barrel to cover the piston rod when the piston rod is exposed from the barrel and wherein the piston rod shield comprises a non-metallic flexible material which substantially returns to shape after deformation.

The piston rod shield may comprise plastic.

The piston rod shield may comprise high density plastic.

The high density plastic may comprise at least one of high-density polyethylene (HDPE) and polyvinyl chloride (PVC).

The guide may form a guide channel and wherein a proximal end of the piston rod shield slides through the guide channel.

The guide channel may conform in shape to outer and inner surfaces of the piston rod shield.

The piston rod shield may be semi-cylindrical and wherein the guide channel may be semi-annular.

The guide may comprise a longitudinally extending flange which bearing on an outer surface of the piston rod shield.

The guide may be fixed to a cap of the barrel.

The guide may be platelike.

The guide may comprise apertures collocating with fastener apertures in a distal face of the cap.

The protection system may further comprise a barrel shield.

The barrel shield may comprise a non-metallic flexible material which substantially returns to shape after deformation.

The non-metallic flexible material may comprise plastic.

The barrel shield may comprise high density plastic.

The high density plastic may comprise at least one of high-density polyethylene (HDPE) and polyvinyl chloride (PVC).

The piston rod shield may slide over the barrel shield.

An outer surface of the barrel shield may conform in shape with an undersurface of the piston rod shield.

The piston rod shield may be semi-cylindrical and the barrel shield may be conformity semi-cylindrical.

The protection system may further comprise a barrel shaft collar holding a mount, the mount engaging an undersurface of the barrel shield.

The mount may comprise apertures therethrough for a rod port hydraulic hose.

A distal end of the piston rod shield may be supported by a shock absorber insert comprising non-metallic flexible material which substantially returns to shape after deformation.

The shock absorber insert may conform to an undersurface of the piston rod shield.

The piston rod shield may be semi-cylindrical and wherein the shock absorber insert may be semicircular/D-shaped.

The shock absorber may comprise high density plastic.

The shock absorber may comprise a thickness of greater than 1 cm.

The protection system may further comprise a piston rod shaft collar holding a mount engaging the shock absorber.

The mount may comprise apertures for fasteners to engage the shock absorber adjacently.

According to another aspect, there is provided a method of protecting a hydraulic cylinder piston having a barrel and a piston rod reciprocating therein using the system described herein, the method comprising applying the system to the cylinder such that the piston rod shield is fixed with respect to the piston rod to move with respect to the barrel so as to cover the piston rod when the piston rod is exposed from the barrel and to substantially return to shape after deformation.

Other aspects of the invention are also disclosed.

DESCRIPTION OF EMBODIMENTS

FIGS.6and7show a typical hydraulic excavator backhoe100such the Komatsu™ PC 5500. The backhoe100comprises a backhoe boom101and a dipper cylinder102controlling a stick/dipper103at a distal end thereof. The stick/dipper103may comprise one or two bucket cylinders104controlling a bucket105at a distal end thereof.

With reference toFIG.2, the cylinder104comprises a barrel106and a piston rod107reciprocating therein under hydraulic pressure. Hydraulic pressure is supplied to the cylinder106via hydraulic hoses107.

The barrel106comprises a cap108comprising a wiper and rod seal109therein. A distal end of the rod107comprises a rod mount110.

A protection system111comprises a flexible non-metallic piston rod shield112fixed to a distal end of the piston rod107to move with the piston rod107with respect to the barrel106to protectively cover the piston rod107when exposed.

The flexible piston rod shield112comprises a material which substantially returns to shape after deformation when being struck by rocks and the like.

The flexible piston rod shield112is non-metallic and may comprise rubber or plastic. In a preferred embodiment comprises high density plastic such as high-density polyethylene (HDPE) or polyvinyl chloride (PVC).

The flexible piston rod shield112may be substantially channel shaped. In the embodiment shown, the piston rod shield112is substantially semi-cylindrical as shown inFIG.1.

The protection system111may comprise a guide113fixed to the barrel106. The guide113may be fixed to the cap108of the barrel106. A proximal end of the flexible piston rod shield112may slide through the guide113.

With reference toFIG.4, the guide113may take the form of a plate and wherein a lower end thereof comprises apertures117for fasteners to go into to collocating apertures119in a face of the cap108. In alternative embodiments, the guide113comprises a rod of metal which is bent to form an arch. The rod itself may be approximately 20 mm in diameter.

The guide113may form a channel114closely conforming to a cross-section of the flexible piston rod shield112. Where the flexible piston rod shield112is semi-cylindrical, the channel114may be correspondingly semi-annular so as to bear closely against both outer and inner surfaces of the flexible piston rod shield112.

The guide113may comprise a longitudinally extending flange115to bear upon the adjacent upper surface of the flexible piston rod shield112.

The system111may further comprise a barrel shield116fixed with respect to the barrel106. The barrel shield116may similarly be flexible in being non-metallic comprising plastic or rubber including high density plastic.

In this embodiment, the flexible piston rod shield112slides over the barrel shield116. The barrel shield116may comprise an outer surface conforming to an inner surface of the flexible piston rod shield112. Where the flexible piston rod shield112is semi-cylindrical, the outer surface of the barrel shield116may be similarly semi-cylindrical and of smaller diameter.

The barrel shield116preferably has sufficient diameter to allow space for hydraulic hosing107for the rod and/or base ports of the cylinder104thereunderneath.

The system100may comprise a barrel shaft collar118engaging the barrel106and supporting a mount120engaging an undersurface of the barrel shield116. The mount120may comprise apertures121therethrough for the rod port hydraulic hose107.

The mount120may support an arched flange125which increases contact surface area with an undersurface of the barrel shield116. The flange125may comprise a plurality of fastener apertures126therethrough.

A distal end of the flexible piston rod shield112may be supported by a conformingly shaped shock absorber insert122. The shock absorber insert122may perform with the distal end of the shield112. In embodiments, insert122may comprises rubber. In alternative embodiments, the insert122comprises high-density plastic, which may be the same material as that of the shield112.

Where the flexible piston rod shield122is semi-cylindrical, the insert122may be semicircular/D-shaped so as to conform to the undersurface of the flexible piston rod shield122.

With reference toFIG.3, the system111may comprise a piston rod shaft collar123holding a piston rod mount124through which longitudinal fasteners engage the adjacent shock absorber insert122.

FIG.6shows the backhoe100wherein the bucket cylinders104are extended such that the flexible piston rod shields112protectively cover the exposed piston rods107.

FIG.7shows the bucket cylinders104retracted wherein the flexible piston rod shields112slide through the respective guides113and over respective barrel shields116.

The term “approximately” or similar as used herein should be construed as being within 10% of the value stated unless otherwise indicated.