Sealing arrangement of tool and method of sealing

Abstract

A seal for a tool of a breaking hammer, a sealing arrangement, a breaking hammer and a method of sealing a tool of breaking hammer is provided. The seal includes a resilient first seal element and a rigid second seal element. The first seal element is fastened to a seal housing and the second seal element is fastened to the first seal element. The second seal element provides mechanical protection for the first seal element.

Claims

1. A sealing arrangement comprising: a tool associated with a breaking hammer; a sealing housing defined by an inner surface located around the tool; an annular gap formed between an outer surface of the tool and an inner surface of the sealing housing; and a sleeve-like seal arranged to seal the annular gap, the seal having an inner periphery, an outer periphery and an axial length, the inner periphery of the seal including first and second tool openings each provided with sealing surfaces arranged to face towards the tool to be sealed, and the outer periphery of the seal being provided with fastening surfaces for fastening the seal to a body of the breaking hammer, wherein the seal includes a first and a second seal element, the first seal element having a first end arranged to face towards the breaking hammer and a second end arranged to face away from the breaking hammer, the first seal element being made of a resilient material and including the first tool opening arranged to be in a resilient contacting relationship with the tool, wherein the fastening surfaces are located on the outer periphery of the first seal element, the first and second seal elements being arranged successively in an axial direction, the second seal element being fastened only to the first seal element, such that the second seal element is without fastening surfaces for fastening it to the body of the breaking hammer, and wherein the second seal element is a rigid element and includes the second tool opening, which is dimensioned to form a sealing clearance between the tool and the second seal element, the second seal element having a cup-like configuration and being configured to cover the first seal element at the portion of the second end, wherein the rigid second seal element is configured to serve as a mechanical shielding element for the resilient first seal element, the fastening between the first seal element and the second seal element being connectable and disconnectable, such that the fastening is based on shape-locking, the resilient first seal element of the seal allowing the rigid second seal element to move transversally together with the tool relative to the sealing housing, wherein the body of the breaking hammer includes a protective casing and the first seal element is fastened to a bottom plate of the protective casing and the entire rigid second seal element is configured to be located outside the body and the first seal element is protected by the rigid second seal element.

2. The seal arrangement as claimed in claim 1, wherein the first seal element is made of a polyurethane material.

3. The seal arrangement as claimed in claim 1, wherein the second seal element is made of a metallic material.

4. A breaking hammer comprising: a percussion device; a tool connectable to the percussion device; a sealing housing located around the tool; and a seal arrangement in accordance with claim 1.

5. The breaking hammer as disclosed in claim 4, wherein the breaking hammer includes a protective casing surrounding the percussion device, the protective casing being provided with a tool aperture through which the tool is arranged to pass.

6. The breaking hammer as disclosed in claim 5, wherein the sealing housing and the seal are located at the tool aperture of the protective casing.

7. The breaking hammer as disclosed in claim 4, wherein the percussion device includes a frame, the sealing housing and the seal being located at a tool side end of the frame.

8. The breaking hammer as claimed in claim 4, wherein the tool is configured to be reciprocated by the percussion device, wherein the reciprocating tool has a maximum axial movement length, and wherein the first seal element has a first axial sealing contact length and the second seal element has a second axial sealing contact length, a total axial sealing contact length of the seal facing the tool being dimensioned to be greater than the maximum axial movement of the reciprocating tool.

9. A method of sealing a tool of a breaking hammer, the method comprising: providing the breaking hammer with at least one seal, the seal including a first seal element made of resilient material and a second seal element made of rigid material, the breaking hammer including a body having a protective casing; arranging the seal in a sealing housing of the breaking hammer; passing the tool through first and second tool openings of the seal; fastening the seal to the sealing housing by means of fastening surfaces of the first seal element; fastening the second seal element only to the resilient first seal element and allowing the rigid second seal element to move transversally together with the tool relative to the sealing housing, wherein the first seal element is fastened to a bottom plate of the protective casing and the entire rigid second seal element is configured to be located outside the body and the first seal element is protected by the rigid second seal element; generating a first sealing function by arranging the resilient material of the first seal element against an outer surface of the tool; and generating a second sealing function by means of a sealing clearance dimensioned between the tool and the rigid second seal element.

10. The method according to claim 9, further comprising shielding, by means of the rigid second seal element, portions of the first seal element that are visible to outside of the breaking hammer, wherein the second seal element serves as a combined sealing and shielding component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic side view of an excavator, which is provided with a breaking hammer.

(2) FIG. 2 is a schematic side view of a seal arrangement.

(3) FIG. 3 is a schematic side view of a first seal element of the seal shown in FIG. 2.

(4) FIG. 4 is a schematic and sectional side view of a second seal element of the seal shown in FIG. 2.

(5) FIG. 5 is a schematic and sectional side view of a lower end portion of a breaking hammer provided with a two-part tool seal.

(6) FIG. 6 is a schematic and sectional descriptive view of a tool side end portion of a breaking hammer.

(7) FIG. 7 is a schematic and sectional side view showing sealing arrangement of a tool of a breaking hammer.

(8) FIGS. 8-11 are schematic views of some alternative structures and mounting principles of the seal.

(9) 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

(10) FIG. 1 shows a breaking hammer 1 arranged at a free end of a boom 2 in 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 includes 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.

(11) The percussion device 4 may be hydraulic, whereby it may be connected to the hydraulic system of the working machine 2. Alternatively, the percussion device 4 may be electrically or pneumatically powered. The impact pulses may be generated in the percussion device 4 by means of a percussion element, such as percussion piston, that may be moved back and forth in the impact direction and return direction under the influence of hydraulic fluid. Further, the breaking hammer 1 may include a protective casing 7, inside which the percussion device 4 may be located.

(12) At a lower end of the breaking hammer, i.e. at the tool side end, is a sealing arrangement 8 for sealing the tool 6 to the surrounding structures of the breaking hammer. The sealing arrangement 8 includes a seal disclosed herein.

(13) FIG. 2 illustrates a seal 9, which is arranged inside a sealing housing 10 and surrounds the tool 6 of the breaking hammer. A tool aperture formed in the protective casing or any other body element of the breaking hammer may serve as the sealing housing. Thus, the sealing housing may have a relatively simple configuration. The seal 9 has a two-part configuration having a first seal element 11 and a second seal element 12. The first seal element 11 is made of a resilient material and it has dual purpose, since it serves as a fastening platform for the second seal element 12 in addition to the sealing feature. The second seal element 12 is made of rigid material and it also has a dual purpose, since it provides mechanical protection for the first seal element 11 in addition to the sealing feature.

(14) As shown in FIG. 4, the second seal element 12 may be a cup-like sealing component and it may include a space 13 for receiving the lower part of the first seal element 11 therein. An outer surface of the first seal element 11 includes fastening means for fastening it to the sealing housing. The fastening means may comprise shoulders 15 and 16. The upper shoulder 15 may be supported against an axial support surface of the sealing housing 10 or structures surrounding the sealing housing. The lower shoulder 16 may be configured to be received by an annular connecting space 17, which is located at the upper part of the second seal element 12. The shoulder 16 and the connecting space 17 together form a shape locking means between the seal elements 11 and 12. As can be noted, the second seal element 12 is without any fastening surfaces for fastening it to the sealing housing 10. However, the second seal element 12 includes an upper axial support surface 18, which is supported against body surfaces surrounding the sealing aperture or housing 10. The axial support surface prevents the second seal element 12 from moving upwards, but on the other hand, allows movement downwards and sideward. Further, an outer surface of the second seal element may have one or more downward tapering portions 19.

(15) The outer periphery of the first seal element 11 further includes an outer sealing surface 20, which is sealed against inner surfaces of the sealing housing 10. The upper shoulder 15 and the resilient material of the first seal element 11 provide the first seal element 11 with a tight sealing against the body. Since the second seal element 12 is intended to be mounted outside the body of the breaking hammer, it is without any sealing surfaces facing towards the body. The first seal element 11 includes a first tool opening 21 and the second seal element includes a second tool opening 22. The first seal opening 21 includes first sealing surfaces 23 that are in a resilient contacting relationship with an outer surface of the tool 6. The first sealing surfaces 23 have first axial sealing contact length L1. The second tool opening 22 includes second sealing surfaces 24 facing towards the tool 6 and forming a clearance sealing with the tool 6. The second sealing surfaces 24 have second axial sealing contact length L2. Total axial sealing contact length of the seal 9 may be relatively great, which ensures good sealing properties for the seal. Since the first seal element 11 has resilient contact sealing and the second seal element 12 has clearance sealing, the diameter D1 of the first tool opening 21 is smaller than the diameter D2 of the second tool opening 22.

(16) FIGS. 2 and 3 further disclose that the first seal element 11 may have one or more transverse through openings 25, the purpose of which are to make the first seal element more bendable and to thereby facilitate mounting of the first seal element 11 to the sealing housing 10. In other words, shaping of the first seal element 11 during mounting is facilitated by openings 25.

(17) FIG. 5 discloses part of a structure of a breaking hammer 1. The breaking hammer 1 includes a lower end A at a tool side end. An upper end, which is not shown in FIG. 5, is provided with mounting means for connecting the breaking hammer 1 to a boom. Inside a protective casing 7 is a percussion device 4, which may include a percussion piston 26 arranged to reciprocate relative to a frame 27 of the percussion device 4. An impact surface 28 of the percussion piston 26 is arranged to strike an upper end 29 of a tool 6.

(18) The tool 6 may be connected to the breaking hammer 1 by means of transverse connecting pins 30. The tool 6 is allowed to move in the axial direction P during use. The tool 6 is supported to the frame of the percussion device 4 by means of an upper tool bushing 31 and a lower tool bushing 32. At the lower end of the breaking hammer 1 is a sealing arrangement 8 including a seal 9 through which the tool 6 passes. The seal 9 is arranged in a sealing housing 10, which surrounds the tool 6. The sealing housing 10 may be formed to be part of a bottom plate 33 of the protective casing 7. As discussed already above, the sealing housing 10 may alternatively be part of the frame 27 of the percussion device 4 if no protective casing 7 exists. Furthermore, it is possible to provide shape locking between the seal 9 and the lower tool bushing 32.

(19) During use of the breaking hammer 1, the tool 6 is subjected to forces in a transverse direction T in addition to operational forces directed in the axial direction P. These transverse forces make the tool 6 move in the transverse direction T. The seal 9 needs to withstand this transverse movement and to keep the sealing tight. In the present solution, the rigid second seal element 12 may move together with the tool 6 in the transverse direction T since fastening of the second seal element 12 has a transverse floating feature FT. Since the second seal element 12 follows continuously the tool 6, it will also provide continuous sealing for the tool 6. In case the rigid second seal element 12 gets stuck to the tool 6 in special circumstances, the second seal element 12 may move a limited distance together with tool in the impact direction. Thus, the second seal element 12 may also have an axial floating feature FA. The floating features FT and FA of the second seal element 12 are enabled by the elastic material of the first seal element 11 and because the second seal element 12 is not directly fastened to the sealing housing 10 or body structure of the breaking hammer 1.

(20) When positioning the seal 9 in the sealing housing 10, the tool 6 is first removed and thereafter the first seal element 11 may be pressed into a smaller outer dimension in order to allow it to be pushed inside the sealing housing 10. When the shaping force is released, the first seal element will automatically press against surfaces of the sealing housing 10. Thereafter, the second seal element 12 is mounted on a protruding portion of the first seal element 11 and is fastened by the shape locking means to the first seal element 11. Finally, the tool 6 is pushed through the seal elements 11 and 12 into its designed place and is locked by means of one or more locking pins. Thus, in the disclosed solution only the tool 6 needs to be dismounted when the seal 9 is changed. The two-part seal 9 prevents effectively impurities from entering inside the structure of the breaking hammer 1. An alternative to the previously described mounting principle is that the two part seal 9 is pre-assembled and is mounted in one piece. The tool 6 locks the seal 9 in place.

(21) FIG. 6 shows the lower part of the breaking hammer of FIG. 5 in another view angle. FIG. 7 shows the previously disclosed lower part of the breaking hammer 1 and the seal arrangement 8 in a more detailed manner.

(22) The sealing housing 10 may include a shoulder 34 against which the upper support surface 15 of the first seal element 11 may be supported. Thus, the mounting of the first seal element 11 may be easier when distance between the upper support surface 15 and an outer surface 35 of the bottom plate 33 is smaller than the total thickness of the bottom plate 33. Further, the thickness of the bottom plate 33 may be dimensioned according to the need without influencing to the mounting of the seal 9.

(23) As an alternative to the previously disclosed solution, the upper support surface 15 of the first seal element 11 may be supported against an inner surface 36 of the bottom plate 33. A further alternative is to provide a lower end portion of the lower tool bushing 32 with fastening surfaces for receiving shape locking surfaces of the first seal element 11.

(24) FIGS. 8 and 9 disclose alternative solutions wherein the breaking hammer 1 is without the protective casing and the seal 9 is fastened to a lower end portion of the frame 27 of the percussion device 4. In FIG. 8, the first seal element 11 is fastened to the lower tool bushing 32 and in FIG. 9 the first seal element 11 is fastened to the bottom plate 33 of the percussion device 4.

(25) As shown in FIG. 10 the seal 9 is fastened directly to the lower end portion of the frame 27 of the percussion device 4. Further, FIG. 11 illustrates that the first sealing element 11 of the seal 9 may envelope the lower end portion of the lower tool bushing 32. An inner diameter at the upper portion of the first seal element may be dimensioned so that a suitable compression and friction forces are generated when it is mounted on the lower end portion of the tool bushing 32.

(26) Although the present embodiment(s) has been described in relation to particular aspects thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred therefore, that the present embodiment(s) be limited not by the specific disclosure herein, but only by the appended claims.