Wedge assembly and method for mounting a power cell in a housing, e.g. in a hydraulic breaker

Abstract

A power hammer of the non-silenced type includes a power cell (100, Figure 6) clamped between opposed, first 11 and second 12 abutment surfaces of a housing 1 by means of an expanding wedge assembly 2

Description

Technical Field

[0001] This disclosure relates to power hammers such as hydraulic hammers for use on work machines such as excavators, and particularly to the so-called non-silenced type where the power cell is mounted rigidly to the housing so that the casing and the power cell vibrate as a single unit. Background

[0002] A hydraulic hammer is a heavy tool that is mounted on a work machine, for example, a work vehicle such as an excavator or backhoe loader, which manipulates the tool and drives it hydraulically to apply a percussive action to a working part or bit. The bit may have a point or a chisel edge for breaking concrete or rock in building demolition, mining and other applications. In such configurations the hammer is often referred to as a breaker, and may have a mass from around 50kg up to around 5000kg or more.

[0003] The percussive action is generated by a so-called power cell, which includes a piston reciprocating in a casing which is usually a heavy steel assembly. The bit is mounted on the casing and typically extends inside the casing where the piston impacts against an inner end of the bit. Often the power cell includes a gas spring or accumulator, which stores energy on the backstroke as the piston is retracted by hydraulic pressure against the piston, and then releases the stored energy to accelerate the piston until it strikes the inner end of the bit. The bit may be removed and replaced when it is worn.

[0004] The power cell is mounted to a housing which typically is made from heavy steel plate and encloses all or part of the power cell. The housing in turn is mounted on the work machine, usually at the top or side of the housing, for example, via a quick coupler or pins that connect the housing to a distal end of the stick on a boom-and-stick excavator. In this way, the casing supports the power cell so that it can be manipulated by the operator of the work machine, e.g. by moving the stick and boom to position the bit against a concrete surface that is to be broken. The power cell may then be connected to the hydraulic supply of the machine so that the machine operator can operate the tool from the cab of the machine.

[0005] Hydraulic hammers can be of the silenced or non-silenced type.

[0006] As referred to herein, a silenced hydraulic hammer means a hydraulic hammer where the casing of the power cell is mounted inside the housing by resilient shock absorbing bodies, often of rubber or polyurethane. These decouple the housing from the vibration of the power cell by allowing the casing to move relative to the housing. The limited movement of the casing is damped by the resilient shock absorbing bodies which attenuate and absorb the vibrational energy that is emitted by the casing of the power cell in directions other than the desired impact direction of the bit. This includes the energy that is reacted against the mass of the housing and the machine by acceleration of the piston and the bit.

[0007] A non-silenced hydraulic hammer means a hydraulic hammer where the power cell is mounted rigidly to the housing so that the casing and the power cell vibrate as a single unit.

[0008] The silenced type reduces the amount of vibration that is transmitted to the machine and the machine operator, but tends to be more costly over the lifetime of the tool since the shock absorbing bodies are degraded by the vibrational energy generated by the tool and must be replaced when worn.

[0009] By way of example, US7628222 B2 discloses a breaker assembly comprising a powercell mounted in a housing between resilient bodies arranged at the top and sides of the housing to suppress propagation of vibrations through the housing. The resilient bodies at the sides of the housing are tapered to generate a clamping force that restrains the powercell in the length direction.

[0010] KR101359322 discloses a breaker assembly comprising a powercell mounted in a housing between resilient bodies arranged at the sides of the housing.

[0011] KR20130021568 A discloses a wedge assembly for restraining movement of a powercell in a casing. The wedge assembly engages the powercell in the front-to-back direction of the casing via contact members, e.g. of rubber or urethane, to suppress vibration caused by the top-to-bottom movement of the piston.

[0012] The non-silenced type do not include such resilient mountings, but instead are arranged to clamp the power cell rigidly to the housing so that there is no relative movement between the housing and the casing of the power cell. Consequently, vibrations generated by the power cell in the casing of the power cell are transmitted directly to the housing, so that the housing and the casing of the power cell vibrate together as one solid part.

[0013] In contrast to the silenced type of hydraulic hammer, in the nonsilenced type it is important to ensure that no relative movement occurs between the power cell casing and the housing, since any such movement will cause progressive damage and failure of the assembly.

[0014] Fig. 1 shows a non-silenced prior art hydraulic breaker 500 of typical construction. The housing 501 is formed as a unitary body, often a weldment as shown, comprising two side plates 502 joined by a top plate 503 which may be bolted to a quick coupler attachment 506, which is configured to be releasably attached to a quick coupler mounted on an excavator or other work vehicle. Either the top plate or the side plates can be arranged to couple to the work machine. The power cell 504 is arranged between the two side plates 502, which are spaced apart to give a close sliding fit between the inner side surfaces of the side plates and the power cell casing. A set of clamp bolts 505 are then installed on either side of the power cell through holes in the two side plates 502, so that each bolt extends across the exposed surface of the power cell cassing in-between the two side plates 502. The bolts 505 are then tightened to slightly distort the housing, drawing the side plates 502 together to clamp the power cell casing between the side plates. Enough friction is generated to prevent movement between the power cell casing and the housing 501, so that in use, both parts vibrate as one.

[0015] The clamping force required to immobilise the power cell in the housing is so large that the clamping bolts used for this purpose are of remarkably large diameter, for example, up to 60mm (with M60 threads) or even larger. Very high torque must be applied to the nuts to achieve the required clamping force, which necessitates the use of a hydraulic torque wrench. Often in practice the required torque is not achieved, and in consequence the power cell casing will begin to vibrate relative to the housing due to the percussive action of the hammer on the tool bit. This relative movement between the power cell and the housing rapidly degrades the components, resulting in failure of the assembly. Summary of the Disclosure

[0016] In accordance with the present disclosure there is provided a power hammer assembly as defined in claim 1.

[0017] In a related aspect, the disclosure provides a method for mounting a power cell in a housing by means of the power hammer assembly.

[0018] The power hammer assembly includes a housing and at least one wedge assembly, and is used in combination with a power cell and a tool bit.

[0019] The power cell includes a casing, a hammer mounted in the casing, and an actuation system operable to reciprocate the hammer in the casing to impact the hammer against the tool bit in an impact direction. A first portion of the casing includes at least one first abutment surface and at least one second abutment surface, the first and second abutment surfaces of the casing being spaced apart along the impact direction at opposite ends of the first portion of the casing.

[0020] The housing is arranged to receive the power cell in a mounted position in the housing.

[0021] A first portion of the housing includes at least one first abutment surface and at least one second abutment surface, the first and second abutment surfaces of the housing being spaced apart along the impact direction at opposite ends of the first portion of the housing in the mounted position of the power cell.

[0022] In the mounted position of the power cell, the or each second abutment surface of the power cell is arranged in confronting relation with a respective said second abutment surface of the housing.

[0023] The or each wedge assembly includes at least two blocks and an adjuster. The at least two blocks are made from metal.

[0024] The wedge assembly defines at least one sliding interface between the at least two blocks, and first and second contact surfaces formed respectively on different respective ones of the at least two blocks.

[0025] The wedge assembly is receivable in the housing, in the mounted position of the power cell, in a use position in-between the casing and the housing, wherein in the use position: the at least one sliding interface extends at an oblique slip angle with respect to the impact direction, the first and second contact surfaces are oppositely facing and spaced apart along the impact direction, the first contact surface is arranged in confronting relation with a respective said first abutment surface of the housing, and the second contact surface is arranged in confronting relation with a respective said first abutment surface of the casing.

[0026] The adjuster is operable in the use position to generate sliding movement between the at least two blocks, at the sliding interface, to urge apart the first and second contact surfaces along the impact direction so as to apply a compressive force between the respective first abutment surfaces of the casing and the housing.

[0027] The first and second abutment surfaces of the housing are arranged to react the compressive force: to immobilise the casing in the housing by clamping the first portion of the casing between the first and second abutment surfaces of the housing, and to transmit vibrational energy, generated in use by the power cell, between the abutment surfaces of the casing and the housing, so that in use, the casing and the housing vibrate as one unit.

[0028] The method includes arranging the power cell in the mounted position, and arranging the at least one wedge assembly in the use position.

[0029] The method further includes operating the adjuster, in the use position, to generate sliding movement between the at least two blocks, at the sliding interface, to urge apart the first and second contact surfaces along the impact direction so as to apply a compressive force between the respective first abutment surfaces of the casing and the housing.

[0030] The method further includes reacting the compressive force, at the first and second abutment surfaces of the housing: to immobilise the power cell casing in the housing by clamping the first portion of the power cell casing between the first and second abutment surfaces of the housing, and to transmit vibrational energy, generated in use by the power cell, between the abutment surfaces of the casing and the housing, so that in use, the casing and the housing vibrate as one unit. Brief Description of the Drawings

[0031] Further features and advantages will be appreciated from the illustrative embodiment which will now be described, purely by way of example and without limitation to the scope of the claims, and with reference to the accompanying drawings, in which:

[0032] Fig. 1 shows a prior art power hammer configured as a hydraulic breaker.

[0033] Fig. 2 shows the power cell of a first power hammer configured as a hydraulic breaker in accordance with an embodiment of the disclosure, respectively: in front view, and in schematic view showing the internal components.

[0034] Fig. 3 shows the housing of the first power hammer, respectively: in front view including a quick coupler fitting, and with the quick coupler fitting removed and one of the second sidewalls cut away.

[0035] Fig. 4 is a top view of the housing.

[0036] Fig. 5 is an internal view of the housing showing one of the metal bodies defining a first abutment surface of the housing.

[0037] Fig. 6 is a front view of the housing with one of the second sidewalls cut away to show the power cell in the mounted position, before installation of the wedge assembly.

[0038] Fig. 7 shows the wedge assembly, respectively assembled and disassembled, in a variant embodiment including a key but otherwise substantially as shown in the other figures.

[0039] Fig. 8 shows the first power hammer with the power cell in the mounted position and the wedge assembly in the use position.

[0040] Fig. 9 corresponds to Fig. 8 with one of the second sidewalls cut away.

[0041] Fig. 10 is an enlarged view of part of Fig. 6.

[0042] Fig. 11 is an enlarged view of part of Fig. 8.

[0043] Fig. 12 is an enlarged view of part of Fig. 9.

[0044] Figs. 13 and 14 are front views corresponding to Fig. 12, wherein Fig. 14 indicates the compressive force F.

[0045] Fig. 15 is a further enlarged view of part of Fig. 9 showing one of the wedge assemblies.

[0046] Fig. 16 illustrates steps in a method of mounting the power cell in the housing.

[0047] Reference numerals and characters that appear in more than one of the figures indicate the same or corresponding parts in each of them. Detailed Description

[0048] Figs. 8 and 9 show a first power hammer including a power cell 100, a tool bit 150 mounted to the power cell, and a power hammer assembly. The assembly includes a housing 1 and at least one wedge assembly 200 for generating a clamping force to immobilise the power cell 100 in the housing 1 when the power cell 100 is received in a mounted position in the housing, as illustrated. The power cell 100

[0049] Referring to Fig. 2, the power cell 100 includes a casing 101, a hammer 130 mounted in the casing 101, and an actuation system 140 operable to reciprocate the hammer 130 in the casing 101 to impact the hammer 130 against the tool bit 150 in an impact direction Di so that the tip of the tool bit applies the impact energy to the workpiece (e.g. a concrete surface, if the tool bit is configured as a breaking tool, as illustrated.) The casing 101 may be made from metal, typically steel.

[0050] The actuation system may be hydraulically powered. The hammer 103 may form the actuator of the actuation system and, as illustrated, may be configured as a piston that reciprocates in a cylinder in or of the casing 101 when energised by a hydraulic power supply 142 from the work machine (e.g. an excavator, not shown) on which the power hammer is mounted. The hydraulic supply may be connected using flexible hoses (not shown) via one or more hydraulic hose couplings 141 provided on the power cell casing 101. The actuation system may include a valve assembly 143 for controlling the flow of hydraulic fluid, and often also a gas spring 144, e.g. a nitrogen accumulator, which is alternately compressed by hydraulic pressure and then released to cause rapid acceleration of the hammer 103 to impact against the tool bit 150.

[0051] A first portion 102 of the casing 101 includes at least one first abutment surface 111 and at least one second abutment surface 112. The first and second abutment surfaces 111, 112 may be made from metal, typically steel, and may be hardened.

[0052] As illustrated, two first abutment surfaces 111 may be formed, each at a respective one of the two opposite sides 103 of the casing 100. The casing may include one or a pair of second abutment surfaces 112, which may be respective parts of a single surface, e.g. the flat bottom end surface of the first portion 102 of the casing, as illustrated.

[0053] The first and second abutment surfaces 111, 112 are arranged at opposite ends of the first portion 102 of the casing 101 so that each of the first abutment surfaces Illis spaced apart from the (or the respective) second abutment surface 112 along the impact direction Di.

[0054] The first portion 102 of the casing 101 may include a pair of chamfers 111' formed on opposite sides 103 of the casing 101, each chamfer 111' defining a respective said first abutment surface 111 of the casing 101.

[0055] A pair of oppositely facing side surfaces 104 may be formed on the opposite sides 103 of the first portion 102 of the casing 101, so that each first abutment surface 111 or chamfer 111' extends away in the width direction Dw from a respective one of the side surfaces 104. The housing 1

[0056] Referring now to Figs. 3-6 and Fig. 10, when considered in the mounted position of the power cell 100 as shown in Figs. 8 and 9, the housing 1 may include two first sidewalls 30 extending in the impact direction Di at opposite first sides 3 of the housing 1. The housing may further include two second sidewalls 40 extending in the impact direction Di and spaced apart by the first sidewalls 30, each second sidewall 40 extending between the first sidewalls 30 in a width direction (Dw) perpendicular to the impact direction (Di).

[0057] The impact direction Di may extend generally in a length dimension of the housing, so the first sidewalls 30 extend in the impact direction or length dimension Di and the depth dimension Dd, and the second sidewalls 40 extend in the impact direction or length dimension Di and the width direction or width dimension Dw, the respective dimensions Di, Dw, Dd being mutually orthogonal.

[0058] The housing 1 may extend in the impact direction Di from a rearward or top end 6 to a forward or bottom end 7, with the tool bit 150 extending from the forward end 7 of the housing. The rearward end 6 of the housing may define a power cell aperture 8, and may be arranged with a mounting flange 13 for attaching the housing to a work machine, e.g. via a quick coupler attachment 506 as known in the art. The quick coupler attachment is used to easily connect and disconnect the power hammer to and from a conventional hydraulic quick coupler device mounted for example at the distal end of the arm or stick of an excavator or other work vehicle.

[0059] The first sidewalls 30 may define respective inner sidewall surfaces 31 spaced apart in confronting relation in the width direction Dw perpendicular to the impact direction Di.

[0060] Generally in this specification, "confronting relation" means that the surfaces are facing generally in opposed directions, whether directly in abutment or separated by a space or another component, or even slightly offset along the axis between them as with the first abutment surfaces 11, 111 as further discussed below.

[0061] A first portion 2 of the housing 1 includes at least one first abutment surface 11 and at least one second abutment surface 12. The first and second abutment surfaces 11,12 may be made from metal, typically steel, and are spaced apart along the impact direction Di at opposite ends of the first portion 2 of the housing 1.

[0062] As illustrated, two first abutment surfaces 11 may be formed, each at a respective one of the two opposite first sides 3 of the housing 1. Each first abutment surface 11 of the housing 1 may be arranged on a respective first sidewall 30.

[0063] The housing 1 may include at least one metal body 50, e.g. a metal plate or block. The metal body 50 is welded to a respective said first sidewall 30 of the housing 1 and defines the first abutment surface 11. As illustrated, a pair of metal bodies 50 may be provided, each welded to a respective one of the first sidewalls 30. The housing 1 including each metal body 50 may be made from steel. The first abutment surfaces 11 may be hardened. The second abutment surface or surfaces 12 may also be hardened.

[0064] As illustrated, the or each second abutment surface 12 of the housing 1 may be proximate the forward end 7 of the housing 1.

[0065] The housing may include one second abutment surface 12 or a pair of second abutment surfaces 12, which may be respective parts of a single surface, e.g. the flat internal bottom end surface of the first portion 2 of the housing, as illustrated.

[0066] As best shown in Fig. 9, in the mounted position of the power cell 100, the or each second abutment surface 112 of the power cell 100 is arranged in confronting relation with the or a respective second abutment surface 12 of the housing 1.

[0067] As illustrated, the second abutment surfaces 112, 12 may be arranged in direct abutment so as to react the compressive force F between those surfaces as further discussed below.

[0068] As illustrated, the casing 101 may be arranged in the mounted position in-between the inner sidewall surfaces 31.

[0069] The first abutment surfaces 11 and the inwardly facing sides of the metal bodies 50 may be spaced apart in the width direction Dwby a distance Dll that is greater than the width DI 02 in the width direction Dw of the first portion 102 of the casing between its side surfaces 104, and so is sufficient to allow the first portion 102 of the casing 101 to slide in-between the first abutment surfaces 11 and metal bodies 50 of the housing 1 when the power cell 100 is introduced slidingly into the housing 1 from the rearward end 6 via the power cell aperture 8.

[0070] As best seen in Fig. 10, each of the side surfaces 104 of the casing 101 may be spaced apart from a respective adjacent inner sidewall surface 31 of the housing 1 by a gap 232' in the mounted position of the power cell. Reference planes PL P2

[0071] A respective, first reference plane Pl is defined to extend through each respective wedge assembly, in the use position, in the impact direction Di and perpendicular to the width direction Dw.

[0072] A second reference plane P2 is defined to extend through the wedge assemblies in the impact and width directions Di, Dw, as indicated in Fig. 4. The wedge assembly 200

[0073] Referring to Fig. 7, the or each wedge assembly 200 includes at least two blocks 220, 230 and an adjuster 240. The at least two blocks 220, 230 are made from metal, for example, steel.

[0074] The or each wedge assembly 200 defines at least one sliding interface 201 between the at least two blocks 220, 230, and first and second contact surfaces 211,212 formed respectively on different respective ones of the at least two blocks 220, 230.

[0075] Referring also to Fig. 9 and Figs. 11 - 15, the or each wedge assembly 200 is receivable in the housing 1, in the mounted position of the power cell 100, in a use position in-between the casing 101 and the housing 1.

[0076] As shown in Fig. 9, two wedge assemblies 200 may be spaced apart in the width direction Dw, respectively at the opposite first sides 3 of the housing 1 in the use position.

[0077] In the use position, the at least one sliding interface 201 extends at an oblique slip angle A201 with respect to the impact direction Di, as illustrated in Fig. 7. The first and second contact surfaces 211, 212 are oppositely facing and spaced apart along the impact direction Di, with the first contact surface 211 arranged in confronting relation with a respective first abutment surface 11 of the housing 1, and the second contact surface 212 arranged in confronting relation with a respective first abutment surface 111 of the casing 101, as best seen in Figs. 12-15.

[0078] The adjuster 240 is operable in the use position to generate sliding movement between the at least two blocks 220, 230, at the or each sliding interface 201, to urge apart the first and second contact surfaces 211,212 along the impact direction Di so as to apply a compressive force F between the respective first abutment surfaces 111, 11 of the casing 101 and the housing 1.

[0079] The first and second abutment surfaces 11, 12 of the housing 1 are arranged to react the compressive force F to immobilise the casing 101 in the housing 1 by clamping the first portion 102 of the casing 101 between the first and second abutment surfaces 11, 12 of the housing 1, and to transmit vibrational energy, generated in use by the power cell 100, between the abutment surfaces 111, 112, 11, 12 of the casing 100 and the housing 1, so that in use, the casing 100 and the housing 1 vibrate as one unit.

[0080] The blocks 220, 230 may be made from a high strength steel. The contact surfaces 211, 212 and / or the abutting surfaces defining the sliding interface 201 may be hardened.

[0081] As illustrated, the at least two blocks may include a centre block 220 and two end blocks 230, with the centre block 220 being arranged between the end blocks 230. The adjuster 240 is operable to generate sliding movement at a respective sliding interface 201 between each of the end blocks 230 and the centre block 220.

[0082] When considered in the first reference plane Pl, in this and other arrangements, the or each respective sliding interface 201 may extend at an oblique slip angle A201 between 120° and 127.5° relative to the impact direction Di.

[0083] Each of the end blocks 230 may be keyed to the centre block 220 at the respective sliding interface 201. As shown in Fig. 7, the key may define a rib 232 that engages slidingly in a groove 234, both being aligned with the direction of motion at the sliding interface 201. (Note that these features are not shown in the other figures.)

[0084] The adjuster 240 may include a screw extending through the end blocks 230 and the centre block 220 along a screw axis Xs. The screw axis Xs may be perpendicular to the impact direction Di and the width direction Dw.

[0085] A respective wedge introduction aperture 42 may be formed in one or (as shown) each of the second sidewalls 40 and configured to accommodate the wedge assembly 200 when the wedge assembly 200 is introduced slidingly through the wedge introduction aperture 42 along the screw axis Xs, in the mounted position of the power cell 100, into the use position. The adjuster 240 may be operated via the wedge introduction aperture 42.

[0086] The adjuster 240 may be threadedly engaged in a threaded aperture in one of the two end blocks 230. To assist during installation and disassembly, a clip 241 may be arranged to retain the blocks together when the adjuster 240 is released.

[0087] As illustrated, the first and second contact surfaces 211,212 may formed respectively on the centre block 220 and the end blocks 230. Thus, the first contact surface 211 may be formed on the centre block 220, and two second contact surfaces 212 may be formed respectively on the two end blocks 230.

[0088] Alternatively, the first and second contact surfaces 211,212 may formed respectively on the end blocks 230 and the centre block 220.

[0089] Irrespective of whether the wedge assembly 200 includes two, three or more blocks, both the first contact surface 211 and the first abutment surface 11 of the housing 1 may be curved when considered, in the use position, in the respective first reference plane Pl. The first contact surface 211 and the first abutment surface 11 of the housing 1 may be respectively concave and convex, or respectively convex and concave.

[0090] The first contact surface 211 and the first abutment surface 11 of the housing 1 may be curved, respectively to different radiuses R211, RI 1.

[0091] The first contact surface 211 may be concave and the first abutment surface 11 of the housing 1 convex, with the first contact surface 211 being curved to a larger radius R211 than the first abutment surface 11 of the housing 1. As further discussed below, this is particularly advantageous where the first contact surface is formed on a centre block 220 between two end blocks 230, as illustrated.

[0092] As shown in Fig. 15, in the use position of the wedge assembly, the first and second contact surfaces 211,212 may be spaced apart by different distances D211, D212 from the respective inner sidewall surface 31 of the housing 1. (The distances D211, D212 are defined to the mid-point of each respective contact area in the width direction Dw.)

[0093] When considered in the second reference plane P2, the second contact surface 212 may define an oblique contact angle A212 with respect to the impact direction Di.

[0094] The oblique contact angle A212 between the second contact surface 212 and the impact direction Di may be between 125° and 135°.

[0095] When considered in the second reference plane P2, the first abutment surface 111 of the casing 101 may be arranged at an oblique abutment angle Alli with respect to the impact direction Di, wherein the oblique abutment angle Alli is equal to the oblique contact angle A212.

[0096] In consequence, when considered in the second reference plane P2 (which is parallel with the plane of the drawing in Fig. 15), the compressive force F acts along a force direction Df that is oblique to the impact direction Di, with respective components of the force F acting in the impact direction Di and the width direction Dw.

[0097] Each of the at least two blocks 220, 230 of the wedge assembly 200 may define a respective outer side surface 221, 231, with the outer side surfaces 221, 231 of each wedge assembly 200 being arranged in the use position in confronting relation to a respective inner sidewall surface 31 of the housing 1.

[0098] The component of the compressive force F acting in the width direction Dw is reacted by abutment of the blocks 220, 230 against the first sidewalls 30 and by the second sidewalls 40 acting in tension between the first sidewalls 30, and between the second contact surfaces 212 by the second portion 102 of the casing acting in compression. The component of the compressive force F acting along the impact direction Di is reacted by the first portion 2 of the housing acting in tension between its first and second abutment surfaces 11, 12, and by the second portion 102 of the casing acting in compression.

[0099] Referring again also to Fig. 7, each respective block (e.g. each end block 230 as illustrated) on which the respective second contact surface 212 is formed may include an extension portion 232 having an inner side surface 233. The outer and inner side surfaces 231, 233 of the block are spaced apart in oppositely facing parallel relation, with the second contact surface 212 forming a shoulder extending away from the inner side surface 233 in the width direction Dw.

[00100] The extension portion 232 is fittingly (i.e. snugly) received in the respective gap 232' between the side surface 104 of the casing 101 and the inner sidewall surface 31 of the housing 1. This helps to centre the power cell 100 in the housing 1 and to stabilise the block 230 in the use position while the adjuster 240 is operated to generate the compressive force F and during operation of the power hammer.

[00101] Referring to Fig. 7, at least one release aperture 202 may be formed between respective ones of the at least two blocks of the wedge assembly. Where the wedge assembly 200 is formed from a centre block and two end blocks, a respective release aperture 202 may be formed between each of the end blocks 230 and the centre block 220. The centre block may include a protruding tail 223 that extends in-between the end blocks 230 as shown to define respective inner sides of the two release apertures 202. Each release aperture 202 is configured to admit a release tool 300 (e.g. a tapered rod or wedge).

[00102] After slacking off the adjuster 240, the release tool 300 can be used to urge the blocks apart along the direction of the sliding interface 201, in the opposite direction to the movement generated by tightening the adjuster 240. The resulting sliding movement between the respective blocks 220, 230 at the sliding interface 201 causes the wedge assembly 200 to contract along the impact direction Di, relieving the compressive force F to allow disassembly.

[00103] A respective release access hole 9 may be formed in the housing 1 to provide access to each respective release aperture 202 in the use position. For example, as illustrated, a pair of release access holes 9 may be formed respectively through the first side walls 30 just below the metal bodies 50. Method

[00104] Referring to Fig. The power cell 100 can be mounted in the housing 1 by the following steps:

[00105] Step A: arranging the power cell 100 in the mounted position.

[00106] Step B: arranging the at least one wedge assembly 200 in the use position.

[00107] Step C: operating the adjuster 240, in the use position, to generate sliding movement between the at least two blocks 220, 230, at the sliding interface 201, to urge apart the first and second contact surfaces 211,212 along the impact direction Di so as to apply the compressive force F between the respective first abutment surfaces 111, 11 of the casing 100 and the housing 1; and reacting the compressive force F, at the first and second abutment surfaces 11, 12 of the housing 1.

[00108] Due to the solid contact between the metal wedge assembly, the housing and the casing, the compressive force F reacted at the first and second abutment surfaces 11, 12 immobilises the power cell casing 101 in the housing 1 by clamping the first portion 102 of the power cell casing 101 between the first and second abutment surfaces 11, 12. This causes the transmission of vibrational energy, generated in use by the power cell 100, between the abutment surfaces 111, 112, 11, 12 of the casing 100 and the housing 1, so that the casing 101 and the housing 1 vibrate as one unit during operation of the power hammer. Industrial Applicability

[00109] By forming the or each wedge assembly with at least two blocks that are driven relative to each other by operation of the adjuster 240, the sliding motion at the sliding interface 201 is assured even if the first abutment surfaces 11, 111 are not perfectly aligned. An arrangement of two end blocks arranged on either side of a centre block is particularly satisfactory in this respect.

[00110] It is found that this arrangement can generate adequate clamping force F, even when the adjusters 240 are configured as screws of relatively modest diameter (e.g. 24mm or M24 threads) compared with the much larger clamping bolts required in prior art assemblies. The relatively small screws are tightened to a torque commensurate with their diameter and so easily applied using conventional tools rather than a hydraulic torque wrench. This greatly improves serviceability and reduces the chance of improper service. The vibrational energy generated by the power cell 100 is transmitted via solid metal-to-metal contact between the respective contact and abutment surfaces, instead of relying on the clamping force of the prior art clamp bolts to generate enough friction to prevent motion in shear at the contact plane between the power cell casing and the prior art housing side plates 502.

[00111] The high clamping force F reacted by solid metal-to-metal contact in the impact direction Di ensures that in use, no relative movement can occur, particularly in the impact direction Di, between the casing 100 and the housing 1 (which is to say, the casing 100 is immobilised in the housing 1), so that they vibrate together simultaneously as one rigid unit.

[00112] In order to generate and react the large clamping force F that is required to immobilise the power cell casing 101 in the housing 1, the wedge assembly 200 preferably is arranged to make face contact between the respective contact and abutment surfaces 211,212, 11, 111 over as large an area as possible, rather than more limited point or line contact which could relieve the large applied forces through progressive plastic deformation of the respective parts.

[00113] At the same time, the housing 1 may require relatively generous tolerances for inaccuracies and distortion introduced during manufacture. For example, it may be desirable for convenience of manufacture to make the housing as a welded assembly. For example, the first abutment surfaces 11 of the housing may be formed respectively on metal bodies 50 (e.g. metal plates) that are welded to the inner sidewall surfaces 31 of the housing. A welded assembly will require larger tolerances for inaccuracies and distortion introduced during welding.

[00114] Preferably, these objectives are reconciled by forming a curve or arc on the confronting surfaces 11,211 of the housing and the wedge assembly. This allows the wedge assembly 200 to move around the curve or arc to obtain flat contact with the first abutment surface 111 of the power cell casing, even if the two first abutment surfaces 11, 111 are not perfectly aligned.

[00115] Further tolerance is obtained by making the respective curved surfaces 11, 211 to different radiuses.

[00116] By making the first contact surface 211 on the centre block 220 concave with a larger radius R211 than the convex first abutment surface 11, the respective radiused surfaces 211, 11 are caused to make contact first at a central contact region. The contact region is enlarged by very slight elastic deformation of the centre block 220 under the high clamping force applied by the end blocks 230, forcing the centre block 220 to make face contact with the radiused first abutment surface 11 of the housing over most or all of the area of the interface between them. In this way the large load F is transferred by extensive area contact between the confronting surfaces 211, 11, even if the welded plate 50 defining the first abutment surface 11 is slightly out of true with respect to the second abutment surface 111 of the casing in the mounted position.

[00117] In summary, a power hammer of the non-silenced type includes a power cell 100 clamped between opposed, first and second abutment surfaces 11, 12 of a housing 1 by means of an expanding wedge assembly 200. The wedge assembly 200 includes at least two metal blocks 220, 230 and an adjuster 240 for displacing the blocks at a sliding interface 201 so as to apply a compressive force F along the impact direction Di of the power cell 100. The contact between the metal wedge assembly 200 and the abutment surfaces 11, 12, 111, 112 of the housing 1 and casing 101 immobilises the power cell 100 in the housing 1 so that the power cell 100 and the housing 1 vibrate as a single unit.

[00118] In the illustrated embodiment, the tool bit is a breaker bar or chisel with a point or edge that applies the impact force to break concrete or other hard material. In alternative embodiments, the tool bit can be any part that applies the impact energy generated by the power cell to the workpiece or material to be worked on, e.g. for driving piles or for setting rivets or for compacting loose material or for any other purpose.

[00119] The tool bit may be mounted to the power cell or to the housing or even to another part of the machine on which the power hammer is mounted, depending on the application.

[00120] The actuation system of the power cell may be driven by any desired power source, e.g. by fluid pressure, hydraulically or pneumatically, or electrically. In each case the actuation system may include an actuator (e.g. an electromagnetic actuator or a piston powered by fluid pressure) which may form the hammer or may be a separate part from the hammer.

[00121] The housing may be configured other than as illustrated. For example, the sidewalls need not fully enclose the power cell 100, and need not be in parallel relation. The housing could be side mounted rather than top mounted (which is to say, the housing may be configured to be attached to the excavator or other work vehicle at one of the sides of the housing rather than at the top of the housing.) The housing could be pinned to the machine rather than bolted to a quick coupling attachment. Such arrangements are well known in the art.

[00122] Rather than arranging the second abutment surfaces 112, 12 in direct abutment, they could react the compressive force F via an intervening component.

[00123] The or each wedge assembly 200 may have more than three blocks, or only two blocks. The blocks may be arranged other than as illustrated.

[00124] Many further adaptations are possible within the scope of the claims.

[00125] In the claims, reference numerals and characters are provided in parentheses, purely for ease of reference, and should not be construed as limiting features. LIST OF ELEMENTS TITLE: Wedge assembly and method for mounting a power cell in a housing, e.g. in a hydraulic breaker FILE: 23-0208GB01 1 Housing 2 First portion of housing 3 First side of housing 6 Rearward end of housing 7 Forward end of housing 8 Power cell aperture 9 Release access hole 11 First abutment surface of housing 12 Second abutment surface of housing 13 Mounting flange 30 First sidewall of housing 31 Inner sidewall surface of first sidewall of housing 40 Second sidewall of housing 42 Wedge introduction aperture 50 Metal body 100 Power cell 101 Casing of power cell 102 First portion of casing 103 Side of casing 104 Side surface of casing 111 First abutment surface of casing 111' Chamfer 112 Second abutment surface of casing Hammer Actuation system Hydraulic hose couplings Hydraulic power supply Valve assembly Gas spring Tool bit Wedge assembly Sliding interface Release aperture First contact surface Second contact surface Centre block Outer side surface of centre block Rib Tail End block Outer side surface of end block Extension portion of block Gap Inner side surface of extension portion Groove Adjuster Clip Release tool Oblique slip angle between sliding interface and impact direction A111 Oblique abutment angle between first abutment surface of casing and impact direction A212 Oblique contact angle between second contact surface and impact direction Dll Distance between first abutment surfaces of housing DI 02 Width of the casing D211 Distance of first contact surface from inner sidewall surface D212 Distance of second contact surface from inner sidewall surface Dd Depth dimension of housing Df Force direction Di Impact direction Dw Width direction F Compressive force Pl First reference plane P2 second reference plane RI 1 Radius of first abutment surface of housing R211 Radius of first contact surface Xs Screw axis PRIOR ART 500 Hydraulic breaker 501 Housing 502 Side plates 503 Top plate 504 Power cell 505 Bolts 506 Quick coupler attachment

Claims

What is claimed is:

1. A power hammer assembly for use with a power cell (100) and a tool bit (150);the power cell (100) including a casing (101), a hammer (130) mounted in the casing (101), and an actuation system (140) operable to reciprocate the hammer (130) in the casing (101) to impact the hammer (130) against the tool bit (150) in an impact direction (Di);a first portion (102) of the casing (101) including at least one first abutment surface (111) and at least one second abutment surface (112), the first and second abutment surfaces (111, 112) of the casing (101) being spaced apart along the impact direction (Di) at opposite ends of the first portion (102) of the casing (101);the assembly including:a housing (1), andat least one wedge assembly (200);the housing (1) being arranged to receive the power cell (100) in a mounted position in the housing (1);a first portion (2) of the housing (1) including at least one first abutment surface (11) and at least one second abutment surface (12), the first and second abutment surfaces (11, 12) of the housing (1) being spaced apart along the impact direction (Di) at opposite ends of the first portion (2) of the housing (1) in the mounted position of the power cell (100);wherein, in the mounted position of the power cell (100), the or each second abutment surface (112) of the power cell (100) is arranged in confronting relation with a respective said second abutment surface (12) of the housing (1);the or each wedge assembly (200) including at least two blocks (220, 230) and an adjuster (240);the at least two blocks (220, 230) being made from metal;the or each wedge assembly (200) defining:at least one sliding interface (201) between the at least two blocks (220, 230), andfirst and second contact surfaces (211,212) formed respectively on different respective ones of the at least two blocks (220, 230);the wedge assembly (200) being receivable in the housing (1), in the mounted position of the power cell (100), in a use position in-between the casing (101) and the housing (1), wherein in the use position:the at least one sliding interface (201) extends at an oblique slip angle (A201) with respect to the impact direction (Di),the first and second contact surfaces (211, 212) are oppositely facing and spaced apart along the impact direction (Di),the first contact surface (211) is arranged in confronting relation with a respective said first abutment surface (11) of the housing (1), andthe second contact surface (212) is arranged in confronting relation with a respective said first abutment surface (111) of the casing (101);the adjuster (240) being operable in the use position to generate sliding movement between the at least two blocks (220, 230), at the sliding interface (201), to urge apart the first and second contact surfaces (211,212) along the impact direction (Di) so as to apply a compressive force (F) between the respective first abutment surfaces (111, 11) of the casing (101) and the housing (i);the first and second abutment surfaces (11, 12) of the housing (1) being arranged to react the compressive force (F):to immobilise the casing (101) in the housing (1) by clamping the first portion (102) of the casing (101) between the first and second abutment surfaces (11, 12) of the housing (1), andto transmit vibrational energy, generated in use by the power cell (100), between the abutment surfaces (111, 112, 11, 12) of the casing (100) andthe housing (1), so that in use, the casing (100) and the housing (1) vibrate as one unit.

2. A power hammer assembly according to claim 1, wherein, when considered in the mounted position of the power cell (100):the housing (1) includes two first sidewalls (30) extending in the impact direction (Di) at opposite first sides (3) of the housing (1);the first sidewalls (30) defining respective inner sidewall surfaces (31) spaced apart in confronting relation in a width direction (Dw) perpendicular to the impact direction (Di);the casing (101) being arranged in-between the inner sidewall surfaces (31); andthe or each first abutment surface (11) of the housing (1) is arranged on a respective said first sidewall (30); andeach of the at least two blocks (220, 230) of the wedge assembly (200) defines a respective outer side surface (221, 231); andthe outer side surfaces (221, 231) of the at least two blocks (220, 230) are arranged in the use position in confronting relation to a respective said inner sidewall surface (31) of the housing (1).

3. A power hammer assembly according to claim 2, wherein, when the or each wedge assembly (200) is considered, in the use position, in a respective, first reference plane (Pl) extending in the impact direction (Di) and perpendicular to the width direction (Dw):the first contact surface (211) is curved, andthe first abutment surface (11) of the housing (1) is curved;the first contact surface (211) and the first abutment surface (11) of the housing (1) being respectively concave and convex, or respectively convex andconcave.

4. A power hammer assembly according to claim 3, wherein the housing (1) includes at least one metal body (50), the metal body (50) being welded to a respective said first sidewall (30) of the housing (1); the metal body (50) defining the first abutment surface (11) of the housing (1).

5. A power hammer assembly according to claim 3, wherein the first contact surface (211) and the first abutment surface (11) of the housing (1) are curved, respectively to different radiuses (R211, RI 1).

6. A power hammer assembly according to claim 2, wherein the at least two blocks include a centre block (220) and two end blocks (230), the centre block (220) being arranged between the end blocks (230); and the adjuster (240) is operable to generate sliding movement at a respective sliding interface (201) between each of the end blocks (230) and the centre block (220); the first and second contact surfaces (211,212) being formed respectively on the centre block (220) and the end blocks (230), or respectively on the end blocks (230) and the centre block (220).

7. A power hammer assembly according to claim 6, wherein the first contact surface (211) is formed on the centre block (220), and the wedge assembly (200) includes two said second contact surfaces (212) formed respectively on the two end blocks (230).

8. A power hammer assembly according to claim 7, wherein, when considered in a first reference plane (Pl) extending in the impact direction (Di) and perpendicular to the width direction (Dw), in the use position of the wedge assembly (200):the first contact surface (211) is curved, andthe or each first abutment surface (11) of the housing (1) is curved;the first contact surface (211) and the first abutment surface (11) of the housing (1) being respectively concave and convex, or respectively convex and concave.

9. A power hammer assembly according to claim 8, wherein the first contact surface (211) is concave and the first abutment surface (11) of the housing (1) is convex, and the first contact surface (211) is curved to a larger radius (R211) than the first abutment surface (11) of the housing (1).

10. A power hammer assembly according to claim 6, wherein each of the end blocks (230) is keyed to the centre block (220) at the respective sliding interface (201).

11. A power hammer assembly according to claim 6, wherein the adjuster (240) includes a screw extending through the end blocks (230) and the centre block (220) along a screw axis (Xs).

12. A power hammer assembly according to claim 11, wherein the screw axis (Xs) is perpendicular to the impact direction (Di) and the width direction (Dw).

13. A power hammer assembly according to claim 12, wherein the housing (1) includes two second sidewalls (40) extending in the impact direction (Di) and spaced apart by the first sidewalls (30), each second sidewall (40) extending between the first sidewalls (30) in the width direction (Dw); anda respective wedge introduction aperture (42) is formed in one or each of said second sidewalls (40);the or each wedge introduction aperture (42) being configured to accommodate the wedge assembly (200) when the wedge assembly (200) is introduced slidingly through the wedge introduction aperture (42) along thescrew axis (Xs), in the mounted position of the power cell (100), into the use position.

14. A power hammer assembly according to claim 2, including two said wedge assemblies (200);the housing 1 including two second sidewalls (40) extending in the impact direction (Di) and spaced apart by the first sidewalls (30), each second sidewall (40) extending between the first sidewalls (30) in the width direction (Dw);the two wedge assemblies (200) being spaced apart in the width direction (Dw), respectively at said opposite first sides (3) of the housing (1) in the use position;respective said first abutment surfaces (11) of the housing (1) being formed at each of the first sides (3) of the housing (1);respective said first abutment surfaces (111) of the casing (100) being formed at each of two opposite sides (103) of the casing (100).

15. A power hammer assembly according to claim 14, wherein in the use position the first and second contact surfaces (211, 212) of the wedge assembly (200) are spaced apart by different distances (D211, D212) from said respective inner sidewall surface (31) of the housing (1), so that, when considered in a second reference plane (P2) extending in the impact and width directions (Di, Dw), the compressive force (F) acts along a force direction (Df) that is oblique to the impact direction (Di).

16. A power hammer assembly according to claim 15, wherein the housing (1) extends in the impact direction (Di) from a rearward end (6) to a forward end (7); and the tool bit (150) extends from the forward end (7) of the housing (1) in the mounted position of the power cell (100); and the rearward end (6) of the housing (1) defines a power cell aperture (8); and the first abutment surfaces (11) of the housing (1) are spaced apart in the width direction by a distance (Dll)sufficient to allow the first portion (102) of the casing (101) to slide between the first abutment surfaces (11) of the housing (1) when the power cell (100) is introduced slidingly into the housing (1) via the power cell aperture (8).

17. A power hammer assembly according to claim 16, wherein the or each second abutment surface (12) of the housing (1) is proximate the forward end (7) of the housing (1).

18. A power hammer assembly according to claim 15, wherein, when considered in the second reference plane (P2), the second contact surface (212) defines an oblique contact angle (A212) with respect to the impact direction (Di).

19. A power hammer assembly according to claim 18, wherein, when considered in the mounted position of the power cell (100) and the use position of the wedge assemblies (200):the first portion (102) of the casing (101) includes a pair of oppositely facing side surfaces (104) formed on the opposite sides (103) of the casing (101);each first abutment surface (111) of the casing (101) extending away inthe width direction (Dw) from a respective side surface (104);each of the side surfaces (104) being spaced apart from a respective adjacent inner sidewall surface (31) of the housing (1) by a gap (232'); andeach respective block (230) on which the respective second contact surface (212) is formed includes an extension portion (232) having an inner side surface (233);the outer and inner side surfaces (231, 233) of the respective block (230) being spaced apart in oppositely facing parallel relation; andthe second contact surface (212) forms a shoulder extending away from the inner side surface (233) of the respective block (230) in the width direction (Dw), andthe extension portion (232) is fittingly received in a respective said gap (232').

20. A power hammer assembly according to claim 18, wherein said oblique contact angle (A212) between the second contact surface (212) and the impact direction (Di) is between 125° and 135°.

21. A power hammer assembly according to claim 1, wherein at least one release aperture (202) is formed between respective ones of the at least two blocks (220, 230); andat least one release access hole (9) is formed in the housing (1) to provide access to the at least one release aperture (202) in the use position;the at least one release aperture (202) being configured to admit a release tool (300) to generate sliding movement between said respective ones of the at least two blocks (220, 230) at the sliding interface (201), to contract the wedge assembly (200) along the impact direction (Di).

22. A power hammer including a power hammer assembly according to claim 1, and a power cell (100);the or each wedge assembly (200) being arranged in the use position;the power cell (100) being arranged in the mounted position and including a casing (101), a hammer (130) mounted in the casing (101), and an actuation system (140) operable to reciprocate the hammer (130) in the casing (101) to impact the hammer (130) against the tool bit (150) in an impact direction (Di); a first portion (102) of the casing (101) including said at least one first abutment surface (111) and said at least one second abutment surface (112) of the casing (100), the first and second abutment surfaces (111, 112) of the casing (100) being spaced apart along the impact direction (Di) at opposite ends of the first portion (102) of the casing (101).

23. A power hammer including a power hammer assembly according to claim 18, and a power cell (100);the or each wedge assembly (200) being arranged in the use position;the power cell (100) being arranged in the mounted position and including a casing (101), a hammer (130) mounted in the casing (101), and an actuation system (140) operable to reciprocate the hammer (130) in the casing (101) to impact the hammer (130) against the tool bit (150) in an impact direction (Di); a first portion (102) of the casing (101) including said at least one first abutment surface (111) and said at least one second abutment surface (112) of the casing (100), the first and second abutment surfaces (111, 112) of the casing (100) being spaced apart along the impact direction (Di) at opposite ends of the first portion (102) of the casing (101);wherein, when considered in the second reference plane (P2), the first abutment surface (111) of the casing (101) is arranged at an oblique abutment angle (Al 11) with respect to the impact direction (Di); the oblique abutment angle (Al 11) being equal to the oblique contact angle (A212).

24. A power hammer according to claim 23, wherein the first portion (102) of the casing (101) includes a pair of chamfers (1111) formed on opposite sides (103) of the casing (101), each chamfer (1111) defining a respective said first abutment surface (111) of the casing (101).

25. A method for mounting a power cell (100) in a housing (1), including: providing a power hammer according to claim 22;arranging the power cell (100) in the mounted position;arranging the at least one wedge assembly (200) in the use position;operating the adjuster (240), in the use position, to generate sliding movement between the at least two blocks (220, 230), at the sliding interface (201), to urge apart the first and second contact surfaces (211,212) along the impact direction (Di) so as to apply a compressive force (F) between therespective first abutment surfaces (111, 11) of the casing (100) and the housing (1); andreacting the compressive force (F), at the first and second abutment surfaces (11, 12) of the housing (1):to immobilise the power cell casing (101) in the housing (1) by clamping the first portion (102) of the power cell casing (101) between the first and second abutment surfaces (11, 12) of the housing (1), andto transmit vibrational energy, generated in use by the power cell (100), between the abutment surfaces (111, 112, 11, 12) of the casing (100) and the housing (1), so that in use, the casing (101) and the housing (1) vibrate as one unit.

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