Breaking hammer and method of supporting percussion piston

Patent metadata

Field	Value
Publication number	US-11828137-B2
Application number	US-202217668870-A
Country	US
Kind code	B2
Filing date	Feb 10, 2022
Priority date	Feb 11, 2021
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

A hydraulic breaking hammer and method of supporting a percussion piston is provided. The breaking hammer includes a percussion device provided with a reciprocating piston. The piston is supported on a frame at its end portions by a first piston bearing element and a second piston bearing element. The second piston bearing element includes a collar sealing element facing towards a working collar of the piston. The piston bearing elements are easily mountable and dismountable separate components.

First claim

What is claimed is:

1. A hydraulic breaking hammer, comprising:
a percussion device including a frame and a piston arranged inside the frame, the percussion device being configured to perform a working cycle including reciprocating longitudinal movement of the piston in an impact direction and a return direction due to pressure of hydraulic fluid fed to first and second working pressure spaces of the percussion device;
at least one control device is arranged for controlling feeding and discharging of the hydraulic fluid of at least one of the first and second pressure spaces for executing the working cycle;
a working collar of the piston located between the first and second working pressure spaces and wherein an outer surface of the working collar is sealed to surrounding structures so that the first and second working pressure spaces are hydraulically separated; and
a first piston bearing and a second piston bearing located at an axial distance from each other, wherein the first and second piston bearings are configured to provide support for opposite first and second end portions of the piston, whereby the first working pressure space, the working collar and the second working pressure space are all located between the first and second piston bearings, the second piston bearing being a separate sleeve-like second piston bearing element mountable to the frame in one piece, wherein a radial clearance is disposed between the outer surface of working collar and the second piston bearing element and at least one separate collar sealing element being arranged to seal the radial clearance, and wherein the second piston bearing element includes at least one first sealing housing for the at least one separate collar sealing element.

2. The breaking hammer as claimed in claim 1 , wherein the first sealing housing is located at a tool side end portion of the second piston bearing element and includes a sealing groove on an inner surface of the second piston bearing element, the separate collar sealing element being a slide ring mounted to the sealing groove.

3. The breaking hammer as claimed in claim 1 , wherein the second piston bearing element is provided with a dedicated lubrication channel.

4. The breaking hammer as claimed in claim 1 , wherein the second piston bearing element is provided with an end cushion space which is configured to form a closed pressure space together with the working collar when the longitudinal movement in the return direction exceeds a predetermined dead point where the longitudinal movement of the piston changes between the return and impact directions.

5. The breaking hammer as claimed in claim 1 , wherein the first and second piston bearings are both replaceable and elongated bearing bushings.

6. The breaking hammer as claimed in claim 1 , wherein the percussion device includes a direct acting pressure accumulator which is located at a return direction end of the piston and is configured to store pressure energy when the second end portion of the piston protrudes inside the direct acting pressure accumulator during the longitudinal movement of the piston in the return direction, the second piston bearing element being provided with at least one second sealing housing at the second end portion facing towards the direct acting pressure accumulator, and wherein the second sealing housing is provided with a gas sealing element facing towards the piston and separating a bearing portion of the second piston bearing element and the direct acting pressure accumulator in a fluid tight manner from each other.

7. The breaking hammer as claimed in claim 1 , wherein the second working pressure space, which is located at a side of the return direction, is limited only by the piston and the second piston bearing element.

8. The breaking hammer as claimed in claim 1 , wherein the first and second piston bearings are both replaceable and elongated bearing bushings and wherein magnitudes of outer diameters of the replaceable and elongated bearing bushings facing radially to the frame are equal, the frame of the percussion device having a central through opening, both end portions of the central through opening having coaxial inner diameters a magnitude of which are equal and match the magnitudes of the equal outer diameters of the replaceable and elongated bearing bushings.

9. The breaking hammer as claimed in claim 1 , wherein the control device is configured to direct substantially constant hydraulic fluid pressure to the first working pressure space for moving the piston in the return direction and wherein the control device is further configured to feed and discharge hydraulic fluid pressure to and from the second working pressure space and to thereby control reciprocating movement of the piston during the work cycle.

10. A method of supporting a piston of a hydraulic breaking hammer, the method comprising:
supporting the piston axially movably relative to a frame of a percussion device of the breaking hammer by means of a first piston bearing and a second piston bearing;
sealing working pressure spaces of the percussion device from each other by means of a sealing element which is located at a working collar of the piston;
arranging the first piston bearing at an impact direction side end portion of the piston and the second piston bearing at an opposite returning direction side end portion of the piston;
using a separate sleeve-like bearing bushing for the second piston bearing element;
providing the second piston sealing bushing with a first sealing housing facing towards the piston;
mounting a changeable collar sealing element to the first sealing housing; and
mounting the second piston bearing bushing together with the changeable collar sealing element to the frame of the percussion device such that the second piston bearing bushing and the changeable collar sealing element are one piece, wherein the second piston bearing element provides bearing and sealing for the piston.

Assignees

• Sandvik Mining & Construction Oy

Inventors

• Oksman Mika
• Nissinen Jyrki
• Laine Juhani
• Moilanen Harri

Classifications

• E21B4/14 Primary

  Fluid operated hammers · CPC title

• B25D9/12 Primary

  comprising a built-in liquid motor {, i.e. the tool being driven by hydraulic pressure} · CPC title

• B25D9/18

  involving a piston-type slide valve · CPC title

• E02D7/10

  with pressure-actuated hammer, {i.e. the pressure fluid acting directly on the hammer structure (E02D7/12 takes precedence; vibrating drivers E02D7/18)} · CPC title

• B25D2250/065

  Details regarding assembling of the tool · CPC title