Patent Application
20170087703
Present disclosure relates to the field of hammers. In particular, the present disclosure relates to a hammer assembly.
Hydraulic hammers are used on work sites to break up large hard objects before such objects can be moved away. Hydraulic hammers may be mounted to back hoes or excavators, or may be hand-held. Typically, the hammer assembly is powered by either a hydraulic or pneumatic pressure source. During a work or power stroke, high fluid pressure is applied to a first shoulder of a piston, thereby driving the piston in a forward direction. The piston then strikes a work tool, which is driven in the forward direction thereby causing a work tip of the tool to strike the rock, concrete, asphalt or other hard object to be broken up. During a return stroke, fluid pressure is applied to a second shoulder of the piston in order to return the piston to its original position.
A hammer assembly may have an accumulator for augmenting the strike power of the piston on the work tool. The accumulators provide for a biasing force to the piston towards the work tool. Generally, such accumulators have a pressurized gas, for example nitrogen, that is contained in a chamber of the hammer On disassembly of the hammer for service or maintenance, the gas is released from the chamber. For releasing the gas inside the chamber special tools may be required. Generally, a gas valve is provided on the hammer that may be opened using a tool to release the gas inside the chamber before the hammer is disassembled. The present disclosure addresses one or more issues with gas pressure during disassembly of hammers.
A hammer including a housing and a piston arranged for reciprocating movement within the housing is disclosed. The hammer further includes a head assembled on the housing and defining a chamber for holding a pressurized gas. The head further includes a wall configured to abut the housing and defining a gas discharge passage extending between the chamber and the housing. A plug is positioned in the gas discharge passage and configured to move or deform under pressure of the pressurized gas in the chamber on separation of the head from the housing.
A hammer including a first member and a second member is disclosed. The first member and the second member are configured for attachment to each other and define a chamber for holding a pressurized gas. Further, a gas discharge passage is defined in the first member and extending between the chamber and an outside surface of the first member. A plug inserted in the gas discharge passage, the plug is retained in the gas discharge passage against the pressure of the gas in the chamber by the second member such that the plug permits escape of gas through the gas discharge passage on separation of the first member from the second member.
A method of assembling a hammer is disclosed. The hammer includes a housing for holding a piston and a head for mounting on the housing and the head defines a chamber for holding a pressurized gas. The head further includes a wall configured to abut the housing and defining a gas discharge passage extending between the chamber and the housing. The method for assembling such hammer includes placing a plug in the gas discharge passage to prevent escape of gas from the chamber, the plug configured to move or deform under pressure of the gas in the chamber on separation of the head from the housing. The method further includes mounting the head on the housing such that the ejection of the plug from the head is prevented by the housing and pressurizing the chamber with a gas.
In the disclosed embodiment, one or more hydraulic cylinders 15 may raise, lower, and/or swing boom 12 and stick 16 to correspondingly raise, lower, and/or swing hammer 20. The hydraulic cylinders 15 may be connected to a hydraulic supply system (not shown) within work machine 10. Specifically, work machine 10 may include a pump (not shown) connected to hydraulic cylinders 15 and to hammer 20 through one or more hydraulic supply lines (not shown). The hydraulic supply system may introduce pressurized fluid, for example oil, from the pump and into the hydraulic cylinders 15. Operator controls for movement of hydraulic cylinders 15 and/or hammer 20 may be located within a cabin 11 of work machine 10.
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A passage 200 is defined in the wall 52 of head 50. The passage 200 works as a gas discharge passage. The passage 200 has a first end 202 fluidly connected to the chamber 100, and a second end 204 on the head flange 54 of the head 50. The passage 200 is suitably sized to permit gas in the chamber 100 to escape through the passage 200. The second end 204 of the passage 200 may define a receptacle 210 for receiving a plug 300. The receptacle 210 may be defined in the wall 52 of the head 50. In other embodiments, the receptacle 210 may be a structure inserted in the passage 200 and configured to selectively retain the plug 300.
The plug 300 may be configured to be press fitted into the receptacle 210 to close the passage 200. In other embodiments, the plug 300 may have a seal 320 that engages an inner surface 230 of the receptacle 210. The seal 320 may fill the clearance between the plug 300 and the inner surface 230 of the receptacle 210. The seal may be a deformable seal. The plug 300 may be of any suitable material, for example rubber, FEP, silicone, etc.
On loosening of the fasteners 60, the housing flange 42 of the housing 40 may get gradually separated from the head flange 54 of the head 50. The gap in between the head flange 54 and the housing flange 42 may permit the plug 300 to partially come out of the receptacle 210 or deform due to the pressure of the gas in the chamber 100 acting on the plug 300. The movement or deformation of the plug 300 may open the passage 200 and allow the pressurized gas in the chamber 100 to escape. Thus, the pressure inside the chamber 100 may be relieved automatically as the fasteners 60 are loosened. Additionally, the sound of the gas leaking via passage 200 on loosening the fasteners 60 may also alert the service personnel about presence of pressurized gas in the head 50. In alternate embodiments, the receptacle 210 or the plug 300 may be provided with a sound indication device, for example a whistle, that may actuated by the pressurized gas escaping from the passage 200 for alerting service personnel.
During assembly of the hammer 20, along with placing other components in the housing 40, the plug 300 may be inserted in the receptacle 210 in the passage 200 defined by the wall 52 of the head 50, before the head 50 is assembled to over the housing 40. The head 50 may be fastened over the housing 40, with the plug 300 placed inside the passage 200. The chamber 100 may be pressurized after the head 50 is assembled over the housing 40.
In an alternate embodiment, the hammer may include a first member and a second member configured for attachment to each other. In the embodiment illustrated in
In an embodiment, the plug 300 placed in the gas discharge passage may abut the second member. In another embodiment, the plug 300 may define a clearance with the gas discharge passage. In an embodiment, the first member may be attached to the second member using bolts. In an embodiment, nitrogen may be used to pressurize the chamber 100.
The present disclosure provides for a method 500 of assembling a hammer 20. The hammer 20 includes a housing 40 for holding a piston 80 and a head 50 is mounted over the housing 40. The head 50 defines a chamber 100 for holding a pressurized gas. Wall 52 of the head 50 is configured to abut the housing 40 and defines a passage 200 extending between the chamber 100 and the housing 40. The method 500 of assembling such hammer 20 includes following steps. Referring to
In an embodiment, the method 500 may further include mounting the head 50 over the housing 40 using bolts. In another embodiment, method 500 may further include providing a seal 320 between the plug 300 and the wall 52 of the head 50 to seal the passage 200. In an embodiment, the method 500 may further include pressurizing the chamber 100 with nitrogen. In another embodiment, the method 500 in step 502 may include providing a sound indication device in the passage 200. In an embodiment, the method 500 may include mounting the head 50 over the housing 40 with the plug 300 inserted in the passage 200 such that the plug 300 abuts the housing 40.
The hammer assembly in accordance with the present disclosure may provide for a discharge passage 200 for pressurized gas present in an accumulator used in the hammer 20. The passage 200 in accordance with the present disclosure obviates need of a valve or any other tools for releasing pressure inside the chamber 100.
If the hammer 20 is disassembled without releasing the pressure inside the chamber 100, the pressurized gas may create an audible noise or hissing sound while escaping. Further, a sound indication device may be placed inside the passage 200. The sound produced by the sound indication device may provide for a warning signal for alerting the service personnel about presence of high pressure in the chamber 100. The service personnel may take appropriate action on hearing such sound alarm. This way any untoward accidents while servicing the hammer 20 may be avoided.
In an embodiment, the passage and the plug may be retrofitted in existing hammers. A passage 200 may be created in the wall 52 of the head 50 using known methods and tools in the art. Such passage 200 may provide for an escape passage for the pressurized gas in the chamber 100. The passage 200 may be fitted with a plug 300. It is understood that the shape and size of the passage 200 and the plug 300 may be chosen as suited for the design of the hammer 10.
The hammer assembly including the passage 200 for accumulators of the present disclosure may provide for a low cost solution for releasing pressure in the chamber 100 of the accumulator. The cost of maintenance of the arrangement as disclosed may be merely cost of replacing the plug 300. In an embodiment, reusable plugs may be used.
