The present invention relates to a hydraulic breaker and in particular but not exclusively a hydraulic breaker having a compressed configuration. The present invention also relates to a machine, such as an excavator, comprising such a hydraulic breaker.

Background Art

Hydraulic breakers are known. A typical hydraulic breaker comprises a power cell supported within a casing. The power cell comprises the head, the cylinder and the lower housing. A tool, such as a chisel, is removably attached to the lower housing.

The breaker is brought into use by being mechanically coupled to the arm of the like of an excavator whereby the breaker is supported by the arm. The hydraulic system of the breaker is coupled to an auxiliary hydraulic system of the excavator to provide motive power to the breaker. Actuation of the breaker by way of its hydraulic system causes reciprocal motion of the tool attached to the lower housing of the power cell whereby concrete, rocks or the like are broken up under action of the tool. During operation there is movement of the power cell and casing in relation to each other. Wear pads are therefore mounted on the inside surface of the casing to protect the casing and, in particular, the power cell. During operation the power cell bears intermittently against the wear pads. The wear pads are thus sacrificial in nature and therefore replaced as the need arises.

The present inventors have become appreciative of the level of noise emitted during use of a hydraulic breaker and also of wear of and, at times, undue stress on the breaker despite the presence of the wear pads.

The present invention has been devised in light of appreciation of the

aforementioned problems. It is therefore an object for the present invention to provide an improved hydraulic breaker comprising a power cell which is supported within a casing. It is a further object for the present invention to provide an improved hydraulic breaker comprising a power cell which is supported within a casing in a compressed configuration.

Statement of Invention

According to a first aspect of the present invention there is provided a hydraulic breaker comprising:

a casing;

a power cell supported within the casing, the casing and power cell

mechanically engaging with each other such that the power cell is compressed,

the hydraulic breaker being configured such that there is no part between an outside surface of a lower housing of the power cell and an inside surface of the casing adjacent the lower housing.

The hydraulic breaker of the present invention comprises a casing and a power cell. The power cell is supported within the casing with the casing and the power cell engaging mechanically with each other, such as by way of cooperating surface profiles, such that the power cell is compressed. The breaker is configured such that there is no part and more specifically no part other than the casing and the power cell, such as one or more wear pads, between an outside surface of a lower housing of the power cell and an inside surface of the casing adjacent the lower housing. The breaker may be configured such that there is no removable part between the outside surface of the lower housing of the power cell and the inside surface of the casing adjacent the lower housing. Contrary to expectations, the present inventors have found that dispensing with wear pads such that there is no part between the outside surface of the lower housing and the inside surface of the casing adjacent the lower housing may address at least one of the aforementioned problems. The breaker may therefore be configured such that there is no wear pad between the outside surface of the lower housing and the inside surface of the casing adjacent the lower housing.

Hydraulic breakers may be either of a suspended form or a compressed form.

According to the suspended form, the power cell is mechanically coupled, such as by way of a suspension arrangement, to the casing at a proximal end of the power cell (i.e. at the head of the power cell). Otherwise the power cell is unattached to the casing. According to the compressed form the power cell and casing engage with each other such that the power cell is compressed. More specifically the power cell and casing define cooperating surface profiles at spaced apart locations. The cooperating surface profiles may be towards a top of the casing and towards a bottom of the casing. The hydraulic breaker may be configured such that a part, such as a buffer component, comprised in the power cell may bear against a part comprised in the casing. The part comprised in the casing may be a flange, such as may be present towards the top of the casing or an interior surface of the bottom of the casing. The profiles of the casing which cooperate with the profiles of the power cell may be spaced apart to an extent that provides for compression of the power cell when the power cell is received in the casing.

The breaker may be configured such that there is substantially nothing other than a gap and more specifically an air gap between the outside surface of the lower housing and the inside surface of the casing adjacent the lower housing. One, other or both surfaces may, nevertheless, have a coating such as is formed by oxidation or deposition of material, for example, plastics material. Known breakers may have a gap between an outside surface of the lower housing and an inside surface of the casing adjacent the lower housing in the range of 6 mm and 30 mm. Such spacing may be between an inwardly oriented surface of a wear pad and the outside surface of the lower housing. In contrast the breaker of the present invention may be configured and more specifically the casing may be configured such that the gap between the outside surface of the lower housing and the inside surface of the casing adjacent the lower housing is at least 1 mm, 2 mm, 3 mm, 4 mm or 5 mm. Alternatively or in addition, the breaker and more specifically the casing may be configured such that the gap between the outside surface of the lower housing and the inside surface of the casing adjacent the lower housing is no more than 6 mm, 5 mm, 4 mm, 3 mm or 2 mm. The gap as defined herein may be in respect of the sum of opposite sides of the breaker such that a single gap is substantially half of the specified distance. Known breakers often have wear pads disposed between the power cell and the casing at locations other than and perhaps further to adjacent the lower housing. The breaker according to the invention may lack wear pads at at least one of two oppositely directed sides of the power cell adjacent at least one of the head and the cylinder. Therefore there may be substantially nothing other than a gap and more specifically an air gap between a surface of the casing and a surface of the power cell at such locations.

Alternatively or in addition the breaker may lack wear pads at a rear of the power cell adjacent at least one of the head and the cylinder. Alternatively or in addition the breaker may lack wear pads at a front of the power cell adjacent at least one of the head and the cylinder. In certain forms of the invention, the breaker may entirely lack wear pads. The inside surface of the casing and the outside surface of the power cell may therefore and for the most part be separated from each other by substantially nothing other than a gap and more specifically an air gap. The size of the gap in a breaker according to the invention may be smaller than a gap in known breakers. The size of the gap in a breaker according to the invention is defined elsewhere herein. Despite lack of wear pads there may be, in certain locations, other than a gap between the outer surface of the power cell and the inner surface of the casing with the number and disposition of such locations depending on the configuration of the breaker. For example mechanical engagement between power cell and casing to provide for the like of suspension or compression may bridge a gap between power cell and casing. By way of further example, breakers comprising an accumulator are known; typically the accumulator is disposed at the front of the breaker such that it is oriented towards a machine to which the breaker is attached. In such a configuration of breaker in accordance with the invention there may be at least one part comprised in or associated with the accumulator between the inside surface of the casing and the outside surface of the power cell. Nevertheless such a part does not constitute a wear pad.

A front surface of the breaker may be directed towards an arm to which the breaker is attached when in use. A rear surface of the breaker may be oppositely directed to the front surface such that the rear surface is generally oriented away from a machine to which the arm is attached. Side surfaces and more specifically first and second side surfaces may be oppositely directed and more specifically substantially orthogonal to the front and rear surfaces.

The breaker may lack wear pads at certain locations as described above. A wear pad may be configured and located such that the power cell bears against the wear pad in preference to the inside surface of the casing. A wear pad may be removably attached to one of an inside surface of the casing and an outside surface of the power cell. More specifically the wear pad may be attached to the inside surface of the casing. The wear pad may be removed when the wear pad has sustained damage from impact arising from movement of the power cell and the casing in relation to each other. The breaker according to the present invention may therefore lack an impact receiving component which is removably attached to one of an inside surface of the casing and an outside surface of the power cell. The impact receiving component may be lacking at one or more locations as described above. For example the impact receiving component may be lacking from between an outside surface of a lower housing of the power cell and an inside surface of the casing adjacent the lower housing. The impact receiving component may be configured to protrude into a space between the power cell and the casing. Movement of the power cell and the casing towards each other may result in one of the power cell and the casing bearing on the impact receiving component in preference to the other of the power cell and the casing. An impact receiving component may generally have the form of a rectangular cuboid. An impact receiving component may be formed of material appropriate for receiving impact from one of the power cell and the casing, such as plastics material or a metal. The hydraulic breaker according to the invention may be configured such that it lacks a removable component between the outside surface of the lower housing of the power cell and the inside surface of the casing adjacent the lower housing, the removable component being configured to receive impact from one of the power cell and the casing. More specifically the hydraulic breaker may be configured such that it lacks a removable component which protrudes into the space between the said parts of the power cell and the casing.

An exterior surface of the casing may be non-planar. More specifically the exterior surface may define at least one protrusion. The at least one protrusion may extend from a generally and more specifically substantially planar land. Where the exterior surface defines plural protrusions, the protrusions may be spaced apart and perhaps substantially equally spaced apart across the surface of the casing. The protrusion may be elongate and may extend generally in a longitudinal direction (i.e. in a direction from head to lower housing of the power cell). The protrusion may extend from part of the casing adjacent the head of the power cell down the casing. Where the casing defines a main aperture, such as an aperture for a hydraulic hose, the protrusion may extend beyond the main aperture. The present inventors have recognised the main aperture as being prejudicial to strength of the casing surrounding the main aperture. Having a protrusion extend beyond the main aperture may improve the structural integrity of the casing. The protrusion may have the form of a rib. The protrusion may define a non-linear path along its length. More specifically, the protrusion may comprise plural linear sections, adjacent linear sections defining an angle therebetween. The at least one protrusion may be defined on a side of the casing. Each of both sides may define at least one protrusion.

The casing may be formed at least in part of plate and more specifically metal plate defining a surface having plural protrusions therefrom. The plural protrusions may extend from an exterior surface of the casing. The plural protrusions may define a regular pattern which extends across the surface. The plate may be Durbar plate. A casing having such an exterior surface may more readily deflect pieces of rock thrown towards the casing during operation of the breaker.

The power cell may comprise three separate components in the form of a head, a cylinder and the lower housing. In known power cells the head, the cylinder and the lower housing are typically mechanically coupled together. Mechanical coupling in such known power cells is by way of tie rods which extend from the head through the cylinder and into the lower housing. Four tie rods are usually present with each tie rod being located towards a respective corner of the power cell. A tie rod is passed through a bore extending through the head and a bore extending through the cylinder in turn such that a threaded exterior of the end of the tie rod is received in and threadedly engages with a blind threaded bore in the lower housing. A nut threaded onto the other end of the tie rod bears against the top of the head of the power cell whereby tightening of the tie rod by way of the nut draws together the head, the cylinder and the lower housing. In larger breakers, the lower housing defines four recesses with each recess being located towards a respective corner. A nut is received in each recess such that it locks in place in the recess and the threaded exterior of the end of the tie rod is received in and threadedly engages with the nut received in the recess. Otherwise each tie rod is of the same form and function as described above.

The present inventors have become aware that tie rods are liable to break after prolonged use of the hydraulic breaker. A consequence of a broken tie rod may be piston facture. An approach to addressing this problem is configuring the power cell such that the head, the cylinder and the lower housing are formed integrally. This approach is, however, expensive. The present inventors have conceived of an alternative approach to addressing the problem. According to the approach, the power cell may be configured such that the lower housing is detached from the cylinder. The power cell may be configured such that the lower housing is detached from the cylinder during use of the hydraulic breaker. More specifically the power cell may be configured such that the lower housing is detached from the head. The compressed configuration of the power cell may provide for the lower housing being urged towards the cylinder whereby the lower housing and the cylinder are held together. Closer spacing of the casing and the power cell according to the invention may provide for the lower housing and the cylinder remaining in alignment to an extent allowing for use of the hydraulic breaker.

The head and the cylinder may be attached to each other by way of at least one mechanical fastener, such as a tie rod. Where a tie rod is used, the tie rod may be shorter than a known tie rod such that the tie rod is configured to be passed through a bore extending through the head such that an end of the tie rod mechanically engages with the cylinder. For example a threaded exterior of the end of the tie rod may be received in and threadedly engage with a blind threaded bore in the cylinder.

Opposing ends of the cylinder and the lower housing may define inter-engaging profiles. An end of one of the cylinder and the lower housing may define a protrusion and an end of the other one of the cylinder and the lower housing may define a recess, the protrusion and recess being configured such that the protrusion is received in the recess. More specifically the protrusion and recess may be configured such that the protrusion is a snug fit in the recess. The end of the cylinder may define the protrusion. The protrusion may have a substantially circular outer surface. More specifically the protrusion may be of annular form albeit integrally formed with the end of the one of the cylinder and the lower housing.

According to a second aspect of the present invention there is provided a machine, such as an excavator, comprising a hydraulic system and a hydraulic breaker according to the first aspect of the present invention, the hydraulic breaker being hydraulically coupled to the hydraulic system. The machine may be configured to be at least one of mobile and stationary. The machine may comprise an arm to which the hydraulic breaker is attached and more specifically removably attached. The arm may be configured, such as by way of at least one hinged or rotating joint, to provide for movement of the hydraulic breaker relative to the machine. Further embodiments of the second aspect of the present invention may comprise one or more features of the first aspect of the first aspect of the present invention.

According to a further aspect of the present invention there is provided a breaker and more specifically a hydraulic breaker comprising: a casing; a power cell supported within the casing, the breaker being configured such that there is substantially nothing other than a gap between an outside surface of a lower housing of the power cell and an inside surface of the casing adjacent the lower housing. The gap may be a fluid gap and more specifically an air gap. The gap may be generally and more specifically substantially uniform around the lower housing.

The breaker may have one of a suspension configuration and a compression configuration. Further embodiments of the further aspect of the invention may comprise one or more further features of any previous aspect of the present invention.

According to a yet further aspect of the present invention there is provided a breaker and more specifically a hydraulic breaker comprising: a casing; a power cell supported within the casing, the breaker being configured such that it lacks a removable component, such as a wear pad, between an outside surface of a lower housing of the power cell and an inside surface of the casing adjacent the lower housing, the removable component being configured to receive impact from one of the power cell and the casing.

The breaker may have one of a suspension configuration and a compression configuration. Further embodiments of the yet further aspect of the invention may comprise one or more further features of any previous aspect of the present invention. The present inventors have appreciated that the feature of the power cell being configured such that the lower housing is detached from the cylinder may be of wider applicability than hitherto described. Therefore and according to a third aspect of the present invention there is provided a hydraulic breaker comprising:

a casing; and

a power cell supported within the casing, the power cell comprising a cylinder and a lower housing,

the lower housing being detached from the cylinder, and the casing and the power cell mechanically engaging with each other such that the power cell is compressed.

Embodiments of the third aspect of the present invention may comprise one or more features of the first aspect of the present invention. Brief Description of Drawings

Further features and advantages of the present invention will become apparent from the following specific description, which is given by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view from one side, the front and above of a breaker according to a first embodiment of the present invention;

Figure 2 is a cut-away view from one side of the embodiment of Figure 1 ;

Figure 3 is a front view of the casing of a second embodiment of breaker;

Figure 4 is perspective view from one side, the front and above of the casing of the embodiment of Figure 3;

Figures 5A and 5B are views from respective opposite sides of the casing of Figure 4;

Figure 6 is a detailed view of the upper end of the casing of the embodiments of Figures 1 and 3;

Figure 7 is a front view of the power cell of a second embodiment of breaker;

Figure 8 is a perspective view of the power cell of Figure 7 from the front, above and one side;

Figure 9 is a side view of the power cell of Figure 7; Figure 10 is a perspective view of a power cell of a third embodiment of breaker when the lower housing and the cylinder are held together;

Figure 1 1A is a perspective view from below of the power cell of Figure 10 when the lower housing and the cylinder are separated; and

Figure 1 1 B is a perspective view from above of the power cell of Figure 10 when the lower housing and the cylinder are separated.

Description of Embodiments A perspective view from one side, the front and above of a hydraulic breaker 10 according to an embodiment of the present invention is shown in Figure 1 . The hydraulic breaker 10 comprises a casing 12 which encloses and supports a power cell 14 in a compressed configuration. Compression is achieved by way of cooperating surface profiles on the casing and the power cell. A first buffer component is present at the top of the head of the power cell. The first buffer component abuts against the downwardly directed surface of the casing flange plate. A second buffer component is present at the bottom of the lower housing of the power cell. The second buffer component abuts against the inside surface of the bottom of the casing. The separation between the downwardly directed surface of the casing flange plate and the inside surface of the bottom of the casing is less than the uncompressed length of the power cell and the first and second buffers whereby when the power cell is received in the casing and the casing flange plate is fitted the power cell is compressed within the casing. Compression as thus described is of known form and function. The hydraulic breaker 10 is removably attached in accordance with known practice at the upper end of the casing 12 to the distal end of an arm on the like of an excavator. A tool such as a chisel is removably attached in accordance with known practice at the lower end of the power cell 14. Furthermore the power cell 14 is coupled to an auxiliary hydraulic system of the excavator in accordance with known practice to provide motive power to the hydraulic breaker 10. Other than is described hereinbelow, the hydraulic breaker 10 is of a form and function that will be familiar to the person of ordinary skill in the art. The power cell 14 of the hydraulic breaker 10 of Figure 1 comprises an accumulator 16 to provide enhanced performance. The casing 12 of the hydraulic breaker 10 is configured to accommodate the accumulator 16. It should be noted that the present invention may be embodied in forms of hydraulic breaker 10 lacking an accumulator.

A cut-away view from one side of the embodiment of Figure 1 is shown in Figure 2. The view of the hydraulic breaker 10 in Figure 2 shows the relative disposition of the casing 12 and the power cell 14. As can be appreciated from Figure 2, there are no wear pads present between the inside surface of the casing 12 and the outside surface of the power cell 14. Furthermore the gap between the inside surface of the casing 12 and the outside surface of the power cell 14 is smaller than in known hydraulic breakers which are configured to accommodate wear pads between their casings and power cells. Considering the gap of the hydraulic breaker 10 of Figure 2 further, the gap is between 0.5 mm and 2.5 mm. Thus the total gap at the front and the back is between 1 mm and 5 mm and the total gap at the two sides is between 1 mm and 5 mm.

A front view of the casing 22 of a second embodiment of hydraulic breaker is shown in Figure 3 and a perspective view from one side, the front and above of the casing 22 is shown in Figure 4. The casing 22 of Figures 3 and 4 is 1006 mm high, 283 mm wide at its widest point at the plate 24 at the top of the casing and 450 mm deep at its deepest point at the plate 24. First and second side views of the casing 22 are shown in Figures 5A and 5B respectively. It should be noted that the casing of the second embodiment is of the same form and function as the casing of the first embodiment except in respect of the lack of ribs extending down the outside of the first embodiment and configuration to accommodate an accumulator. Such features are described below in respect of the first embodiment of Figures 1 and 2.

Furthermore the second embodiment of casing is employed in a hydraulic breaker of smaller size than the first embodiment of casing. Although not shown in the drawings of the second embodiment, the casing 22 is formed from Durbar plate whereby a regular pattern of protrusions are present on the exterior surface of the casing 22. Durbar plate is normally not used for larger hydraulic breakers according to the first embodiment on account of Durbar plate being of insufficient thickness. Figure 6 provides a detailed view of the upper end 32 of the casing of the embodiments of Figures 1 and 3. As can be seen from Figure 6, the rear of the casing 32 defines two elongate apertures 34 which extend down from the plate 36 at the top of the casing and which are spaced apart across the rear of the casing.

When a power cell is received within the casing 32, a respective member which protrudes from the rear of the power cell is received in each elongate aperture 34. The elongate nature of the apertures 34 provides for movement of the power cell relative to the casing when the hydraulic breaker is in use. The engagement of power cell members and casing elongate apertures 34 provides for compression of the power cell within the casing.

A front view of the power cell of a second embodiment of breaker is shown in Figure 7. Figures 8 and 9 respectively show a perspective view of the power cell of Figure 7 from the front, above and one side and a side view of the power cell of Figure 7. The power cell 42 of Figures 7 to 9 is of a form lacking an accumulator and is thus accommodated in a casing of the form shown in Figures 3 to 5B. The power cell is 925 mm high, 162 mm wide and 178 mm deep. The form and function of a power cell according to the second embodiment is nevertheless the same as the first embodiment in respect of the lack of wear pads and a smaller gap between the power cell and casing compared with known hydraulic breakers. In accordance with known design, the power cell 42 of Figures 7 to 9 comprises three main parts, namely: the head 44, the cylinder 46 and the lower housing 48.

Returning now to consider the first embodiment of Figures 1 and 2, aside from configuration of the casing 12 to accommodate the accumulator 16, each of the two sides of the casing comprises first 18 and second 20 ribs which extend from the top of the hydraulic breaker 10. The first and second ribs 18, 20 improve the structural integrity of the casing 12. The first rib 18 extends from the front of the casing part way towards the rear of the casing and downwards to an extent corresponding to the head of the power cell. The second rib 20 extends from the rear of the casing downwards to an extent corresponding to the head of the power cell before defining an angle and extending towards the front of the casing and further downwards to an extent such that the main opening through which the accumulator protrudes is bridged.

A power cell 60 of a third embodiment of breaker is illustrated in Figures 10, 1 1A and 1 1 B. As can be seen from Figure 10, the power cell 60 comprises a head 62, a cylinder 64 and a lower housing 66. Although represented as integrally formed in Figure 10, the head 62 and the cylinder 64 are separate components which are attached to each other by four tie rods (not shown) with each tie rod being located towards a respective corner of the head and the cylinder. Each tie rod is in the form of a bolt and is of a length such that it passes through a bore extending through the head 62 and is received in the upper end of the cylinder 64. A captive thread is located at the upper end of the cylinder 64. The exterior surface of the end of the tie rod is threaded such that the end of the tie rod threadedly engages with the captive thread. The head of the tie rod bears against the top of the head 62. Rotation of each tie rod by way of the head of the tie rod therefore draws the head 62 and the cylinder 64 together. In larger breakers, the tie rods are of different form with each tie rod being threaded at each end. The end of each such tie rod is received in and threadedly engages with a captive thread as described above. Tightening of each tie rod of this alternative form is by way of rotation of a nut which is threadedly engaged with the top of the tie rod and bears against the top of the head 62 whereby the head 62 and the cylinder 64 are drawn together. The lower housing 66 is detached from the cylinder 64. There are, for example, no tie rods extending from the cylinder 64 into the lower housing to provide for attachment of lower housing and cylinder.

Instead, the lower housing 66 and the cylinder 64 are urged towards each other by the compressive force exerted by the casing whereby the lower housing and the cylinder are held together. Providing for compression is described above with reference to Figure 1 .

As can be seen from Figures 1 1 A and 1 1 B, which show the ends of the lower housing 66 and the cylinder 64 when the lower housing and the cylinder are separated from each other, the opposing ends of the lower housing and the cylinder define inter-engaging profiles. The end of the cylinder 64 comprises an annular protrusion 68 and the opposing end of the lower housing 66 comprises a recess 70 shaped to receive the annular protrusion 68. When the lower housing 66 and the cylinder 64 are brought together as shown in Figure 10, inter-engagement of annular protrusion 68 and recess 70 restricts relative lateral movement of the lower housing and the cylinder such that the lower housing and the cylinder remain sufficiently aligned during use of the power cell 60. As described above the compressive force exerted by the casing holds the lower housing and the cylinder together to an extent allowing for use of the power cell 60. Otherwise the form and function of the piston 60 and of a breaker comprising the piston 60 are as described above with reference to previous embodiments.