Hammer piston

Abstract

A piston (210) for a hydraulic hammer of a working machine (100) is disclosed. The piston (210) comprises a first part (300) having a first diameter, a second part (302) having a second diameter larger than the first diameter and having a plurality of grooves (306), and a third part (304) having a third diameter smaller than the second diameter.

Description

Technical Field

[0001] The present disclosure generally relates to a hammer assembly for a work machine, and more specifically, to a piston of the hammer assembly.

Background Art

[0002] Work machines such as excavators, backhoes, skid steers, wheel loaders, tractors, etc. are provided with hammer assembly tools for crushing rocks, concrete, soil materials, or the like. Such hammer tools can be hydraulically driven, utilizing a hydraulic circuit to which hydraulic fluid is supplied to operate the hammer assembly. Generally, a hydraulic hammer includes a piston or hammer that provides a reciprocating motion to strike a tool for disassembling rocks, soil, concrete, or other materials. The reciprocating piston can be driven by high-pressure fluid from a hydraulic circuit system. The force of the reciprocating piston can be transmitted to the material being crushed when the piston strikes the work tool.

[0003] The piston of a hydraulic hammer used in a work machine is an important component that is subject to significant stress and strain during hammer operation. One of the main problems is the effect of the surface area and contact pressure of the piston on mating parts, which can lead to an increase in galling or damage to the piston. The high speed and pressure of the hydraulic fluid during piston stroke within the hammer can cause erosion of the piston, resulting in performance degradation and shortening of piston life. Grooves provided on the piston connecting different hydraulic passages can also become clogged or blocked, reducing fluid flow, leading to an increase in pressure within the system, and shortening the life of the piston.

[0004] Others have disclosed pistons for hydraulic hammer assemblies, but have not been able to provide pistons with a sufficiently long service life. For example, U.S. Patent No. 4,951,757 ("'757 Patent") discloses a hydraulic breaker having a piston having a five-stage configuration including first, second, third, fourth, and fifth stages arranged continuously along the axial direction of the piston. The third stage has a smaller diameter than the fourth stage, and the third stage has six flat notches on its outer surface that allow hydraulic fluid to pass through the cylinder of the hammer assembly.

[0005] Therefore, it is clear that there is a need for improved piston designs for hydraulic hammer action that reduce gore and damage to the piston and extend the piston's lifespan and effective life. [Overview of the Initiative]

[0006] According to one aspect of the present disclosure, a piston for a hydraulic hammer of a work machine is disclosed. The piston comprises a first portion having a first diameter, a second portion having a second diameter greater than the first diameter and having a plurality of grooves, and a third portion having a third diameter smaller than the second diameter.

[0007] In another aspect of this disclosure, a hammer assembly for use with a working machine is disclosed herein. The hammer assembly comprises a cylinder, a piston reciprocally mounted within the cylinder, and a hammer tool coupled to the piston. The piston includes a first portion having a first diameter, a second portion having a second diameter greater than the first diameter and having a plurality of grooves, and a third portion having a third diameter smaller than the second diameter.

[0008] Another aspect of the present disclosure discloses a method for manufacturing a piston for a hammer assembly of a working machine. The method includes providing the piston as a metal bar and machining the piston to include a first part, a second part, and a third part, so that the first part has a first diameter, the second part has a second diameter greater than the first diameter, and the third part has a third diameter smaller than the second diameter; and machining the second part to include a plurality of grooves on the second part.

[0009] These and other aspects and features of this disclosure will be more readily understood when read in conjunction with the accompanying drawings, and when the following detailed description is also read. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view of a work machine including a hammer assembly according to an embodiment of the present disclosure. [Figure 2] This is a side view of the hammer assembly shown in Figure 1, according to an embodiment of the present disclosure. [Figure 3] This is a cross-sectional view of the hammer assembly of Figure 1 along line 3-3 in Figure 2, according to an embodiment of the present disclosure. [Figure 4] This is a perspective view of the piston used in the hammer assembly shown in Figure 2, according to an embodiment of the present disclosure. [Figure 5] This is a cross-sectional view of the hammer assembly along line 3-3 in Figure 2 during a fixed impact energy cycle according to an embodiment of the present disclosure. [Figure 6] This is a flow diagram of the hydraulic circuit of the hammer assembly shown in Figure 5 in a fixed impact energy cycle according to an embodiment of the present disclosure. [Figure 7] This is a cross-sectional view of the hammer assembly along line 3-3 during the start-up cycle according to an embodiment of the present disclosure. [Figure 8] This is a schematic diagram of the hydraulic circuit of the hammer assembly shown in Figure 7 during the starting cycle according to an embodiment of the present disclosure. [Figure 9]This is a cross-sectional view of the hammer assembly along line 3-3 during a lifting cycle according to an embodiment of the present disclosure. [Figure 10] This is a schematic diagram of the hydraulic circuit of the hammer assembly shown in Figure 9 during the lifting cycle according to an embodiment of the present disclosure. [Figure 11] This is a cross-sectional view of the hammer assembly along line 3-3 during a firing cycle according to an embodiment of the present disclosure. [Figure 12] This is a schematic diagram of the hydraulic circuit of the hammer assembly shown in Figure 11 during the firing cycle according to an embodiment of the present disclosure. [Figure 13] This is a cross-sectional view of the hammer assembly along line 3-3 in the return cycle according to an embodiment of the present disclosure. [Figure 14] This is a schematic diagram of the hydraulic circuit of the hammer assembly shown in Figure 13 during the return cycle, according to an embodiment of the present disclosure. [Figure 15] This is a flowchart of a method for manufacturing the piston shown in Figure 4 according to an embodiment of the present disclosure.

[0011] The figures illustrate one embodiment of the present invention for illustrative purposes only. Those skilled in the art will readily recognize from the following considerations that alternative embodiments of the structures and methods illustrated herein can be employed without departing from the principles described herein. [Modes for carrying out the invention]

[0012] Referring here to the drawings, and in particular to the illustrated embodiments, an exemplary working machine 100 is shown, illustrated as a backhoe loader. A backhoe loader is a heavy machine designed to move soil material from the ground or surface at excavation sites in the construction and agricultural industries. While the following detailed description illustrates exemplary embodiments relating to a backhoe loader, it will be understood that this description also applies equally to the use of the present disclosure in other working machines, including but not limited to shovel-type excavators, front-end loaders, skid steers, wheel loaders, and tractors.

[0013] Referring to Figure 1, the working machine 100 includes a frame 102 supporting an engine 104. The frame 102 is supported on ground engagement elements 106, which are illustrated as wheels. It should be assumed that the ground engagement elements 106 may be any other type of ground engagement element 106, such as a track. The working machine 100 further includes a working mechanism 108 extending from the frame for performing work, for example, crushing the ground surface, soil, concrete, rock, or other materials at an excavation site. The frame 102 may be an upper slewing body common to excavators and working machines in agriculture, construction, and mining. The working mechanism 108 includes a boom 110, an arm 112, a bracket 114, and a hammer assembly 116. The hammer assembly 116 may be attached to the working mechanism 108 via the bracket 114. It can also be recognized that the hammer assembly 116 may be attached to the working mechanism 108 via a coupler, a quick coupler, or a hydraulic quick coupler, as is generally known in the art.

[0014] The hammer assembly 116 may be hydraulically operated and may be connected to one or more hydraulic supply lines 118 via a hydraulic work machine circuit (not shown) comprising a work machine 100. The hydraulic work machine circuit may raise, lower, and / or pivot the arm 112 and boom 110, and accordingly raise, lower, and / or pivot the hammer assembly 116. The work machine 100 may include a pump (not shown) connected to the hydraulic work machine circuit and the hammer assembly 116 through one or more hydraulic supply lines 118. The hydraulic circuit may introduce a pressurized fluid, such as oil, from the pump to one or more hydraulic supply line 118 cylinders and to the hammer assembly 116. Operator controls for moving and operating the hydraulic work machine circuit and / or the hammer assembly 116 may be located in the operator's cab 120 of the work machine 100.

[0015] Referring now to FIG. 2, a side view of the hammer assembly 116 is illustrated. The hammer assembly 116 may include a hammer housing 200 and a hammer tool 212. A portion of the hammer tool 212 is coupled to the hammer housing 200. The hammer tool 212 may have a portion assembled within the hammer housing and a portion protruding from an end of the hammer housing 200 for disassembling rock, soil, concrete, or other materials, as is generally known in the art.

[0016] Referring now to FIG. 3, a cross-sectional view of the hammer assembly 116 taken along line 3-3 of FIG. 2 is illustrated. The hammer assembly 116 may include a hammer housing 200, an accumulator 202, a check valve 204, a spool valve 206, a pressure control valve 208, a piston 210, and a hammer tool 212. The piston 210 is coupled to the hammer tool 212 for reciprocating movement within a cylinder 214 in the hammer housing 200. The hammer tool 212 extends outside the hammer housing 200 on the side opposite the bracket 114 for contacting and / or crushing rock, gravel, soil, ground, and the like when the piston 210 strikes the hammer tool 21 during operation of the hammer assembly 116. The pressure control valve 208 may be provided within the hammer assembly 116 to maintain a maximum hydraulic pressure to ensure that the hammer assembly 116 delivers all strikes for crushing rock and the like at maximum output when the piston 210 strikes the hammer tool 212 during operation of the hammer assembly 116.

[0017] FIG. 4 depicts a perspective view of piston 210 of hammer assembly 116 according to an embodiment of the present disclosure. Piston 210 includes a first portion 300 having a first diameter D1, a second portion 302 having a second diameter D2, a third portion 304 having a third diameter D3, a plurality of grooves 306 on the surface of the second portion 302, and a striking end 308 that reciprocally impacts hammer tool 212. Piston 210 may be a hammer or another piston type that provides a reciprocating impact motion to hammer tool 212, as is generally known in the art.

[0018] Piston 210 and hammer tool 212 are located within cylinder 214 within hammer housing 200. Piston 210 reciprocally impacts against hammer tool 212 within cylinder 214. When piston 210 repeatedly impacts hammer tool 212 of cylinder 214, the surface of the second portion 302 of piston 210 may interact with the surface of cylinder 214, causing surface wear and gouging of piston 210.

[0019] The second diameter D2 of piston 210 is designed to be larger than both the first diameter D1 and the third diameter D3 such that the second portion 302 interacts with cylinder 214 during operation of hammer assembly 116. The second diameter D2 may further include three timing grooves within the plurality of grooves 306 to reduce the surface area of the second portion 302. The depth of the plurality of grooves 306 creates a hydraulic passage for hydraulic fluid, such as oil, to flow between the second portion 302 and the surface of cylinder 214. The third diameter D3 of piston 210 may be smaller than the second diameter D2, but may be larger than the first diameter D1, while the second diameter D3 remains larger than both the first diameter D1 and the third diameter D3.

[0020] Multiple grooves 306 may be machined into the second part 302 to a depth ranging from 3 to 10 mm. It may be noted that the machining depth may increase or decrease when forming multiple grooves on the surface of the second part 302. The additional surface area provided to the piston 210 in the second part 302 having a maximum diameter, second diameter D2, reduces contact pressure and the possibility of goring or damage to the piston 210 when the piston 210 repeatedly contacts the cylinder 214 during the reciprocating motion of the hammer assembly 116 within the cylinder 214. The depth of the multiple grooves 306 creates hydraulic passages for hydraulic fluid to circulate within the cylinder 214.

[0021] Multiple grooves 306 are positioned on the second section 302 at various positions to allow hydraulic fluid to pass through hydraulic passages when the piston 210 is at a specific position within the cylinder 214 as the piston 210 moves in a reciprocating impact motion against the hammer tool 212. For example, when the piston 210 is at its highest position within the cylinder 214, the hydraulic fluid may circulate through the hydraulic passages formed by the three timing grooves on the second section 302, but the hydraulic fluid may not circulate when the piston 210 is at the center of the cylinder 214. The multiple grooves 306 are sometimes referred to as “timing grooves” because they are positioned on the second section 302 to synchronize the timing of the circulation of hydraulic fluid at a specific position within the cylinder 214.

[0022] Figure 5 illustrates a cross-sectional view of the hammer assembly 116 along line 3-3 in Figure 2 during a fixed impact energy cycle in one embodiment of the present disclosure. Figure 6 illustrates a hydraulic circuit of the hammer assembly 116 of Figure 5 for a fixed impact energy cycle during the operation of the piston 210 within the hammer assembly 116 in one embodiment of the present disclosure. A hydraulic work machine circuit within the work machine 100 may be operably connected to a hydraulic hammer line 400 within the hammer assembly 116 that can supply pressurized fluid to cause the piston 210 to reciprocate alternately in a working stroke and return stroke pattern, as is generally known in the art. Operator control for the movement of the working mechanism 108 and / or the hammer assembly 116 may be located within the operator's cab 120 of the work machine 100. Driven by a hydraulic supply, the piston 210 inside the hammer housing 200 may provide reciprocating impact motion to the hammer tool 212, which may in turn be applied to a material such as rock or concrete that comes into contact with the hammer tool 212. The hammer tool 212 is intended to include any known tool capable of interacting with the piston 210 and the ground, rock, or other material. The hammer tool 212, or a part thereof, may move in and out of the hammer housing 200 during operation, such as when the piston 210 provides the hammer tool 212 with reciprocating impact motion.

[0023] The hammer assembly 116 can operate under a fixed strike energy cycle using the hydraulic work machine circuit of the work machine 100, which is connected to the hydraulic hammer circuit 500 within the hammer assembly 116. In this hydraulic hammer circuit 500, a pressure control valve 208 has a specific opening pressure for the return flow of the hydraulic work machine circuit in the work machine 100 to the tank 502. The fixed operating pressure is used to control the sequence of accumulator 202 pressures. This ensures that the energy of the hammer assembly 116 is maximized before the piston 210 begins to move. The fixed strike energy cycle provides the force to move the piston 210. This cycle does not regulate the force that pushes or drives the piston 210 downward toward the hammer tool 212.

[0024] The hammer assembly 116 performs a series of operating cycles that provide the force to move the piston 210 in a reciprocating motion within the cylinder 214. The operating cycles include a start cycle, a lift cycle, a firing cycle, and a return cycle. Multiple grooves 306 are provided on the second portion 302, and during various operating cycles of the hammer assembly 116, they may create hydraulic passages 402 for the hydraulic fluid supply unit to pass through the hydraulic hammer line 400. In one embodiment, three timing grooves are provided within the multiple grooves 306 at predetermined positions on the second portion 302 of the piston 210, thereby creating hydraulic passages 402 at different locations within the cylinder 214 that circulate the hydraulic fluid at different times as the piston 210 reciprocates in a stroke and return stroke pattern within the cylinder 214.

[0025] Figure 7 illustrates a cross-sectional view of the hammer assembly 116 along line 3-3 of Figure 2 during a starting cycle in another embodiment of the present disclosure. Figure 8 illustrates a hydraulic hammer circuit 500 of the hammer assembly 116 of Figure 7 for a starting cycle of the piston 210 in the hammer assembly 116 in another embodiment of the present disclosure. During the starting cycle, the hydraulic fluid supply from the hydraulic work machine circuit flows through the check valve 204 to both the accumulator 202 and the lifting region 600 near the bottom of the piston 210. A spring force may hold the pressure control valve 208 closed. This blocks the hydraulic fluid from flowing into the drive region 602 above the piston flange, preventing the piston (5) from moving. The pressure inside the hammer assembly 116 increases, and a gas, such as nitrogen gas, is compressed inside the accumulator 202.

[0026] Figure 9 illustrates a cross-sectional view of the hammer assembly 116 along line 3-3 in Figure 2 during a lifting cycle in another embodiment of the present disclosure. Figure 10 illustrates a hydraulic hammer circuit 500 of the hammer assembly 116 of Figure 9 for a lifting cycle of the piston 210 in the hammer assembly 116 in another embodiment of the present disclosure. During the lifting cycle, when a preset operating pressure threshold is reached and the accumulator 202 is charged, the pressure control valve 208 opens. The pressure control valve 208 then directs hydraulic fluid from the drive region 602 above the upper flange 604 of the piston 210 to the tank 502 in the work machine 100. The piston 210 begins to move upward due to the high fluid pressure at the bottom of the lower flange 606 of the piston 210. The upper flange 604 of the piston 210 pushes the hydraulic fluid from the drive region 602 to the tank 502 in the work machine 100.

[0027] Figure 11 illustrates a cross-sectional view of the hammer assembly 116 along line 3-3 in Figure 2 during a firing cycle in another embodiment of the present disclosure. Figure 12 illustrates a hydraulic hammer circuit 500 of the hammer assembly 116 of Figure 11 for a firing cycle of the piston 210 in the hammer assembly 116 in another embodiment of the present disclosure. During the firing cycle, when the piston 210 is in its highest position, hydraulic fluid from the lifting region 600 at the bottom of the piston 210 is directed through the pilot passage 608 to the left end of the spool valve 206. The spool valve 206 then shifts to the right. This causes the accumulator 202 to connect with the upper flange 604 of the piston 210, which supplies hydraulic fluid to the upper flange 604 of the piston 210. The upper flange 604 of the piston 210 is placed under pressure to actuate the piston 210, initiating a downward impact stroke toward the hammer tool 212 within the cylinder 214.

[0028] Figure 13 illustrates a cross-sectional view of the hammer assembly 116 along line 3-3 of Figure 2 during a return cycle in another embodiment of the present disclosure. Figure 14 illustrates a hydraulic hammer circuit 500 of the hammer assembly 116 of Figure 13 for a return cycle of the piston 210 in the hammer assembly 116 in another embodiment of the present disclosure. During the return cycle, the velocity of the piston 210 increases as the piston 210 moves downward. The operating pressure decreases during the impact stroke, causing the pressure control valve 208 to close the pilot passage 608. When the piston 210 strikes the hammer tool 212, the hydraulic passage formed by the multiple grooves 306 connects the pilot passage 608 to the tank line 700. This releases the pressure at the left end of the spool valve 206. This allows the spool valve 206 to return to the left. The hydraulic fluid under the upper flange 604 of the piston 210 may act as a hydraulic brake 702 on the piston 210. The hydraulic brake 702 protects the piston 210 and cylinder 214 from idle stroke. At this point, the piston 210 is returned to its starting position, ready for the next cycle.

[0029] Industrial applicability In operation, this disclosure may find applicability in many industries, including but not limited to construction, civil engineering, mining, and agriculture. Specifically, the technology of this disclosure may be used to break up various materials such as rock, concrete, asphalt, or other soil materials, used with various working machines, including but not limited to excavators, backhoes, skid steers, wheel loaders, tractors, and similar machines. While the above detailed description is made with particular reference to hammer assemblies of working machines, it should be understood that the teachings may also apply to other hammer assemblies that utilize pistons, such as concrete breaking tools, hammer breakers, and similar machines.

[0030] Referring here to Figure 14, there is a method 800 for manufacturing a piston 210 for a hammer assembly 116 of a working machine 100. In the first step 802, the piston is supplied as a metal bar. In step 804, the piston 210 is machined to include a first part 300, a second part 302, and a third part 304, thereby the first part 300 having a first diameter D1, the second part 302 having a second diameter D2 which is greater than the first diameter D1, and the third part 304 having a third diameter D3 which is smaller than the second diameter D2. It may be recognized that the piston 210 may initially be supplied as a metal bar made of steel, or as other material commonly used for pistons and hammers.

[0031] In step 806, the second portion 302 is machined to include a plurality of grooves 306 on its surface. For example, three timing grooves may be machined on the second portion 302 as a plurality of grooves 306. The three timing grooves may be rectangular and may be machined to a depth of up to 10 mm. In some embodiments, the three timing grooves may have a depth of 5 mm, 6 mm, or 7 mm. The three timing grooves may be elongated to allow an elongated hydraulic passage to be formed within the cylinder 214. The piston 210 may be provided within the cylinder 214 of the hammer assembly 116 so that the piston repeatedly strikes the hammer tool 212 during operation within the hammer assembly 116.

[0032] From the above, it can be understood that the technology disclosed herein has industrial applicability in a variety of situations, including but not limited to construction, mining, and agricultural machinery that utilizes a hammer assembly with a working tool for crushing rock, soil, or other materials.

Claims

1. A piston (210) for a hydraulic hammer of a work machine (100), wherein the piston (210) is A first portion (300) having a first diameter, A second portion (302) having a second diameter larger than the first diameter, and having a plurality of grooves (306), A piston (210) comprising a third portion (304) having a third diameter smaller than the second diameter.

2. The piston (210) according to claim 1, wherein the plurality of grooves (306) include three timing grooves (306).

3. The piston (210) according to claim 1, wherein the three timing grooves (306) are oriented vertically and the plurality of grooves (306) are formed into a rectangular shape.

4. The piston (210) according to claim 1, wherein the piston (210) is made of steel and the plurality of grooves (306) are machined to a maximum depth of 10 mm.

5. A hammer assembly (116) for use with a work machine (100), Cylinder (214) and The piston (210) according to claim 1, A hammer assembly (116) comprising a hammer tool (212) coupled to the piston (210).

6. Accumulator (202), Check valve (204), Valve spool (206), A hydraulic hammer operably associated with the pressure valve (208), The hammer assembly (116) according to claim 5, wherein the hammer assembly (116) includes a hydraulic hammer circuit (500) which provides hydraulic fluid to a hydraulic lifting region (600) adjacent to the third portion (304) of the piston (210) to lift the piston (210) away from the hammer tool (212), and the hydraulic hammer circuit (500) provides the hydraulic fluid to a drive region (602) adjacent to the first portion (300) of the piston (210) to drive the piston (210) relative to the hammer tool (212).

7. The hammer assembly (116) according to claim 6, wherein the plurality of grooves (306) include three timing grooves (306), the plurality of grooves (306) are machined to a maximum depth of 10 mm, and the plurality of grooves (306) form a plurality of hydraulic passages (402).

8. The hammer assembly (116) is coupled to the working mechanism (108) of the working machine (100), and the working machine (100) is Frame (102) and A ground engagement element (104) that supports the frame (102), The prime mover of the work machine (100) mounted within the frame (102), The work mechanism (108) extends from the frame (102), The hammer assembly (116) according to claim 7, comprising the hammer assembly (116) and an operable hydraulic circuit.

9. A method (800) for manufacturing a piston (210) for a hammer assembly (116) of a working machine (100), wherein the method (800) is The piston (210) is provided as a metal bar, Machining the piston (210) to include a first portion (300), a second portion (302), and a third portion (304), such that the first portion (300) has a first diameter, the second portion (302) has a second diameter larger than the first diameter, and the third portion (304) has a third diameter smaller than the second diameter. A method (800) comprising machining the second portion (302) to include a plurality of grooves (306) on the second portion (302).

10. The hammer assembly (116) is a hydraulic hammer having a hydraulic hammer circuit (500), and the method (800) is To provide the piston (210) within the cylinder (214) of the hammer assembly (116), wherein the hammer assembly (116) includes an accumulator (202), a check valve (204), a valve spool (206), a pressure valve (208), and a hammer tool (212) that is operable with the piston (210) within the cylinder (214), The hammer assembly (116) is operated such that the piston (210) strikes the hammer tool (212), By providing hydraulic fluid to the hydraulic lifting region (600) adjacent to the third portion (304) of the piston (210), the piston (210) is lifted away from the hammer tool (212), The method according to claim 9 (800), further comprising driving the piston (210) to strike the hammer tool (212) by providing the hydraulic fluid to a hydraulic drive region (602) adjacent to the first portion (300) of the piston (210).

11. The above method (800) The hammer assembly (116) is coupled to the working mechanism (108) of the work machine (100), wherein the work machine (100) comprises a frame (102), a ground engagement element (106) supporting the frame (102), a prime mover mounted within the frame (102), the working mechanism (108) extending from the frame (102), and a hydraulic circuit operable with the hydraulic hammer circuit (500). The method according to claim 10 (800), further comprising operating the hammer assembly (116) from the operator's cab of the work machine (100).

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