Abstract
A pressure accumulator, rock breaking machine and method of storing pressure energy. The accumulator includes a casing and an elastic membrane arranged inside the casing. The membrane divides an inner space of the casing into two separate pressure spaces. A gas space is prefilled with pressurized gas. On the opposite side of the membrane is a hydraulic space for receiving hydraulic fluid. The membrane is a hat-like element having side walls, a mounting flange at its open end and a closed top end. The mounting flange of the membrane is mounted between the casing and a flange element. The accumulator is without a screen. The flange element is provided with a sealing for sealing a piston.
Claims
1. A hydraulic rock breaking machine, comprising: a percussion device including a frame and a piston arranged inside the frame and configured to perform reciprocating longitudinal movement due to pressure of hydraulic fluid fed to the percussion device; a tool connectable to the percussion device and configured to receive impact pulses from the percussion device; a hydraulic system of the percussion device, the hydraulic system including a feed port for feeding hydraulic pressure fluid into the percussion device and a discharge port for discharging the pressure fluid out of the percussion device, and pressure conduits for directing the pressure fluid to and out of working pressure spaces of the piston; and a pressure accumulator for storing hydraulic pressure energy and being connected to the hydraulic system, wherein the pressure accumulator is located at an extension of the piston so that an upper end of the piston moves inside a hydraulic space of the accumulator during the operation of the percussion device and wherein the accumulator comprises: a casing defining an inner space; an elastic membrane arranged inside the inner space and configured to divide the inner space into two separate pressure spaces, wherein a gas space is prefilled with pressurized gas, and on the opposite side of the membrane is a hydraulic space for receiving hydraulic fluid; a flange element, wherein the membrane has radial side walls, edges at its open first axial end and a closed top end at its opposite second axial end, wherein the edges of the membrane are mounted between the casing and the flange element, the edges of the membrane having a transverse mounting flange, whereby the membrane has a hat-like configuration, the mounting flange of the membrane being pressed in an axial direction of the accumulator between the casing and the flange element; the flange element including at least one pressure channel for feeding hydraulic fluid to the hydraulic space and for discharging hydraulic fluid, whereby the pressure channel allows provision of hydraulic fluid flow from a hydraulic operating system of the rock breaking machine to and out of the hydraulic space during the operation of the machine; the flange element including a central sleeve-like support portion protruding axially inside the casing, whereby an outer surface of the support portion is configured to provide axial support for the membrane at least when the hydraulic rock breaking machine is non-pressurized; and wherein an inner surface of the support portion of the flange element is provided with sealing elements for sealing an end portion of the piston.
2. The breaking machine as claimed in claim 1, wherein the flange element includes an annular mounting portion transverse to the axial direction of the accumulator, wherein the pressure channels are located at the mounting portion.
3. The breaking machine as claimed in claim 1, wherein the edges of the membrane are provided with at least one protrusion at least on one side of the membrane to serve as a sealing element, and wherein at least one of the axial mounting surfaces between the casing and the flange element is provided with a groove for receiving the at least one protrusion.
4. The breaking machine as claimed in claim 1, wherein an axial length of the sleeve-like support portion of the flange element is at least ¼ of an axial length of the accumulator.
5. The breaking machine as claimed in claim 1, wherein outer side surfaces of the sleeve-like support portion of the flange element are slanted towards a distal end of the support portion so that the support portion tapers towards the distal end.
6. The breaking machine as claimed in claim 1, wherein the top surface portion facing towards the gas space and the top surface includes an annular edge portion, a central portion and an annular recess portion therebetween.
7. The breaking machine as claimed in claim 1, wherein the side walls of the membrane are angled relative to the axial central line of the accumulator, whereby the side walls open towards the open end of the membrane.
8. The breaking machine as claimed in claim 1, wherein the hydraulic space of the accumulator is connected to the hydraulic system of the percussion device and pressure fluid is configured to flow towards the hydraulic space and out of the hydraulic space during operation of the percussion device.
9. The breaking machine as claimed in claim 1, further comprising at least one valve for adjusting pressure of the hydraulic fluid prevailing in the hydraulic system connected to the pressure accumulator.
10. The breaking machine as claimed in claim 1, wherein a top end of the percussion piston facing towards the hydraulic space of the accumulator is rounded.
11. A method of storing hydraulic pressure energy of a rock breaking machine, the method comprising: providing the rock breaking machine with at least one pressure accumulator in accordance with claim 1, the pressure accumulator including a gas space and a hydraulic space separated by a membrane, the membrane having a cup-like configuration provided with a closed top end, an open end and side walls between the ends; prefilling the gas space with pressurized gas; receiving a top end portion of a reciprocating piston of a percussion device of the rock breaking machine inside the hydraulic space during operation of the percussion device, whereby hydraulic volume inside the hydraulic space changes due to a protruding top end portion of the piston; compensating the volumetric change in the hydraulic space by allowing the membrane to expand towards the gas space; and using the membrane; using the pressure accumulator; and mounting the membrane by pressing a mounting flange, which is located at an open end of the membrane, axially between two axial mounting surfaces.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0059] Some embodiments are described in more detail in the accompanying drawings, in which
[0060] FIG. 1 is a schematic side view of an excavator, which is provided with a hydraulic breaking hammer,
[0061] FIGS. 2-4 are schematic and sectional side views of a percussion device and its accumulator,
[0062] FIGS. 5-7 are schematic views of a hat-shaped membrane of an accumulator,
[0063] FIGS. 8 and 9 are schematic views of a flange element provided with a truncated support portion and a sleeve element,
[0064] FIG. 10 is a diagram showing some issues relating to a hydraulic rock breaking machine, and
[0065] FIG. 11 is a schematic view of a rock drilling unit.
[0066] For the sake of clarity, the Figures show some embodiments of the disclosed solution in a simplified manner. In the Figures, like reference numerals identify like elements.
DETAILED DESCRIPTION OF SOME EMBODIMENTS
[0067] FIG. 1 shows a breaking hammer 1 arranged on a free end of a boom 2 of a working machine 3, such as an excavator. Alternatively, the boom 2 may be arranged on any movable carriage or on a fixed platform of a crushing apparatus. The breaking hammer 1 comprises a percussion device 4 for generating impact pulses. The breaking hammer 1 may be pressed by means of the boom 2 against material 5 to be broken and impacts may be simultaneously generated with the percussion device 4 to a tool 6 connected to the breaking hammer 1. The tool 6 transmits the impact pulses to the material 5 to be broken. The percussion device 4 is hydraulically operable, whereby it may be connected to the hydraulic system of the working machine 2. The impact pulses may be generated in the percussion device 4 by means of a percussion piston, which is moved back and forth in the impact direction and return direction under the influence of hydraulic fluid. At a rear end 7 of the breaking hammer is a hydraulic pressure accumulator, which is shown in FIGS. 2-4.
[0068] FIG. 2 discloses a rear end 7 or upper end portion of a breaking hammer 1. A hydraulic accumulator 8 is located at an extension of a percussion device 4, which comprises a piston 9 movable in impact direction A and return direction B. In FIG. 2 the piston 9 has executed its striking movement and is located in its lowermost position. The accumulator 8 comprises a casing 10 which is mounted against an axial mounting surface 11 of a body 12. The accumulator 8 further comprises a flange element 13, which may be pressed by means of fastening screws of the casing 10 against the mounting surface 11. Inside the accumulator 8 is an elastic membrane 16, edges of which are mounted between the casing 10 and the flange element 13. The membrane 16 divides the inner space of the casing 10 into a gas space 17 and a hydraulic space 18. The hydraulic space 18 is best shown in FIG. 4. As can be seen, the flange element 13 provides the membrane 16 with support. Inside the gas space 17 is pressurized gas. The casing 10 is provided with a feed port 19 for feeding pre-filling gas into the gas space 17. The hydraulic space 18 is connected to operating hydraulic system of the percussion device 4 via pressure channels 20. A top end 22 of the piston 9 moves inside the flange element 13 and causes volumetric change in hydraulic fluid inside the hydraulic space 18. The top end portion of the piston 9 is sealed by means of seals 23 to the flange element 13. Reciprocating movement of the piston 9 is controlled by means of a sleeve-like control valve 24 arranged around the piston 9 and provided with control surfaces for controlling hydraulic pressure affecting on working pressure surfaces of the piston 9. A first working pressure surface (not shown) is continuously pressurized and moves the piston 9 towards the return direction B. Hydraulic pressure affecting on a second working pressure surface and a third working pressure surface is controlled by means of the control valve 24. Working pressure surfaces are subjected selectively to hydraulic fluid flow of a high pressure circuit and tank pressure circuit. The top end 22 of the piston 9 is subjected continuously to low pressure since the accumulator 8 is connected to a low pressure circuit. When the control valve 24 connects working pressure surfaces to the high pressure circuit, then the piston 9 moves towards the impact direction A because surface areas of the working pressure surfaces are greater compared to the surface area of the first working pressure surface. Also the low pressure prevailing in the accumulator 8 and affecting on the top surface 22 generates forces for moving the piston 9 in the impact direction A.
[0069] FIG. 2 further discloses that the flange element 13 may comprise a sleeve-like portion 28 protruding towards the front end and surrounds the control valve 24. Then the flange element 13 is capable of providing support for the control valve 24 and is also provided with pressure channels. Thanks to the sleeve-like portion 28 of the flange element 13 the structure of the basic body 12 may be simple. Different collars, fittings and pressure channels are easier to form to the separate component 13 than to the large-sized body 12.
[0070] FIG. 2 further discloses that the inner surface of the casing 10 and the membrane 16 both have shapes substantially corresponding to a shape of a hat. The casing 10 may comprise a protective sleeve 32 surrounding the accumulator 8.
[0071] In FIG. 2 the gas space 17 is prefilled with pressurized gas and the hydraulic space 18 is non-pressurized since the percussion device is not active. Therefore the gas pressure presses the membrane 16 against an outer surface of protruding support portion 14 of the flange element 13. As can be noted, central portion of the membrane 13 may then contact the top surface 22 of the piston 9 and also slanted surfaces of a recess 53 at a top of the support portion. In FIG. 3 the hydraulic space 18 is still non-pressurized, but the piston 9 has moved in return direction B because a tool of the breaking machine 1 is pressed against a material being broken.
[0072] In FIG. 4 the percussion device 4 is pressurized and the piston 9 is moved in return direction B to its rearmost position. Then hydraulic fluid is pushed by the piston 9 and the membrane 16 is forced towards the inner surface of the casing 10. Volume of the gas space 17 is decreased. Small arrows demonstrate that the membrane 16 expands axially and laterally during the return movement of the piston 9.
[0073] FIGS. 2-4 further show that edges 33 of the membrane 16 comprise an annular mounting flange 21, which is provided with a protrusion 34 facing towards a top surface of an annular mounting part 15 of the flange element 13. The mounting part of the flange element 13 is provided with a groove 35 or other form surface which may receive the protrusion 34 whereby they may together form a sealing element. Alternatively or in addition to, the protrusion 34 may be formed on the top side of the mounting flange 21 and the casing 10 may be provided with the groove 35. The accumulator 8 and all its components are mounted and dismounted in axial direction. The casing 10 is tightened by fastening screws against the rear mounting surface 11 of the body 12. Then the mounting flange 21 of the membrane 16 is pressed by axial force F tightly between axial counter surfaces of the casing 10 and the flange element 13.
[0074] FIG. 4 further discloses that top end 22 of the piston 9 may comprise rounded outer edges 50. Alternatively, the entire top end may have curved configuration 51.
[0075] FIGS. 2-4 also disclose that the pressure channels 20 are located at root portion of the flange element 13 and that the membrane 16 is arranged to close them when the prefilled gas pressure of the gas space 17 pushes the membrane 16 towards the flange element 13 and the hydraulic space 18 is non-pressurized. Then the membrane closes the pressure channels 20, as it is shown in FIGS. 2 and 3. In FIG. 4 the membrane 16 is in its expanded state and the pressure channels 20 are open, of course.
[0076] FIGS. 5-7 disclose a membrane 16 having a hat-like shape with a closed end 53 and an annular mounting flange 21 at an open end 54. Then edges 33 of the membrane 16 are provided with an annular transverse portion. The mounting flange 21 may comprise a protrusion 34 which may be a sealing bulge. Inside the membrane 16 may or may not be several ribs 55. The top end 53 of the membrane 16 may comprise a curved central portion 39. Between the top surface and the mounting flange 21 are angled side walls 40, and between the side walls and the top surface there is a curved intermediate portion 41 or recess. An annular edge 56 may be curved too. Further at a root portion there may be a curved section 57 with an increased material thickness. This part of the membrane 16 may serve as valve portion as it is disclosed above in this document. The shape of the membrane 16 may resemble a cowboy hat.
[0077] FIGS. 8 and 9 disclose a flange element 13 provided with an integrated support portion 14 and a sleeve-like portion 28. The disclosed flange element 13 is a multi-purpose component serving as an axial support membrane, as a mounting support for the membrane, and also providing needed control pressure channels and support for the control valve and operating system.
[0078] A top of the support portion 14 is open so that the piston can pass through it. Side surfaces 58 of the support portion 14 are slanted so that the support portion tapers towards it distal end. Outermost edge 59 is rounded. All the other features are already disclosed above in this document.
[0079] FIG. 10 is a diagram showing that a hydraulic rock breaking machine 43 may be a hydraulic breaking hammer 1 or a rock drilling machine 44. Common features of these machines is at least the fact that they both include a hydraulic percussion device 4 and a hydraulic accumulator 8. Furthermore, they are used to break rock or rock material. Structure of the percussion device 8 and its detailed operational principle may deviate from what has been disclosed in FIGS. 2-4. Thus, the disclosed accumulator 8 may be applied versatile with different constructions.
[0080] FIG. 11 discloses a rock drilling unit 45 comprising a rock drilling machine 44 supported movably on a feed beam 46. The rock drilling machine 44 comprises a percussion device provided with a reciprocating piston 9 arranged to strike an impact surface of a shank 47. A drilling tool 48 is connected to the shank 47 and the shank 47 may be rotated by means of a rotating device 49. When a drill bit 60 is pushed and simultaneously impact pulses are directed to the drilling tool 48, the drill bit crushes rock material and a drill hole 61 is formed. In order to compensate pressure fluctuation caused by the reciprocating movement of the piston 9, there is a hydraulic accumulator 8 at an axial extension of the percussion device 4. The accumulator 4 comprises a casing, a flange element and an elastic membrane between them. The basic structure of the accumulator 4 is in accordance with the features and issues disclosed in this document.
[0081] The drawings and the related description are only intended to illustrate the idea of the invention. In its details, the invention may vary within the scope of the claims.
