Self-cleaning excavator bucket assembly

Abstract

A bucket assembly 2 for mounting on a boom of an excavator. The bucket assembly comprises a mounting coupling for attachment to the boom. The mounting coupling comprises a pair of first and second mou

Description

FIELD OF THE INVENTION This invention relates to relates to an improved self-cleaning excavator bucket assembly incorporating a material ejecting mechanism. BACKRGOUND OF THE INVENTION Excavators comprising an articulated arm, typically comprising a boom pivotally mounted on the vehicle and a dipper arm pivotally mounted on an end of the boom, having a bucket mounted on a coupler located at a distal end of the dipper arm are commonly used for excavating soil, for example for digging drainage ditches or digging trenches for drainage pipes. A common problem with such excavators, particularly when digging high clay content soil, is the difficulty in removing material from the bucket, particularly for the relatively long and narrow buckets used for trenching operations. Normally this is achieve by operating the excavator to violently shake the bucket to dislodge material from the bucket. However, this relatively violent movement of the bucket this can result in rapid wear or damage to the excavator if done excessively. Previous attempts have been made to provide an excavator bucket which is selfcleaning, where a cleaning member which is pivotally mounted within the bucket and driven to actively discharge material from the bucket to ensure that the bucket is emptied for another stroke, thus significantly increasing productivity as each load fills the bucket and is fully emptied. This is particularly important where the material being lifted is sticky or otherwise does not flow easily from the bucket leaving significant amounts of material within the bucket. On narrow buckets the problem is exacerbated to the point the bucket clogs entirely reducing digging efficiency. However, prior art attempts to mount such cleaning members within buckets along with suitable actuators, such as hydraulic rams, have met with limited success, primarily due to the lack of space within the bucket for such cleaning mechanisms. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a bucket assembly for mounting on a boom of an excavator comprising: a mounting coupling for attachment to the boom, said mounting coupling comprising a pair of first and second mounting pins arranged parallel to one another and being of predetermined diameter and spacing; the bucket having an outer wall with a front digging edge to cut into material to be lifted and with the outer wall trailing behind the front digging edge; the bucket having side walls for confining the material onto the outer wall; a rear wall attached to the mounting coupling; and a pivotal pusher plate being mounted on the bucket for pivotal movement about an axis transverse to the bucket at so as to be movable from a retracted position at the rear wall to a forward position in which the pusher plate moves forwardly relative to the outer wall to push material from the outer wall for discharge; wherein the pusher plate is pivotal about a pivot axis coaxial with said first mounting pin; a ram having a first end coupled to the pusher plate for moving the pusher plate between its retracted and forward positions, wherein said ram has a second end pivotally coupled to the bucket at a pivot axis coaxial with said second mounting pin. Preferably the pusher plate is pivotally mounted on the first mounting pin via a pair of spaced mounting flanges respectively located on or adjacent either end of the first mounting pin. The second end of the ram may be pivotally mounted on the second mounting pin via a pair of spaced mounting flanges respectively located on or adjacent either end of the second mounting pin. The outer wall preferably forms a part of a cylinder centred on an axis coaxial with the first mounting pin so that pivotal movement of the pusher plate between its retracted and forward positions causes an outer edge of the pusher plate to sweep across the outer wall and causes respective side edges of the pusher plate to sweep over the side walls of the bucket. The side walls of the bucket may converge towards one another from the rear wall towards the front digging edge of the outer wall. The rear wall of the bucket may incorporate an opening to allow passage of the ram therethrough. The ram may comprise a double acting hydraulic ram. An opening may be provided at a rear side of the bucket between a rear end of the outer wall and a rear end of the rear wall to allow material to pass therethrough. According to a further aspect of the present invention there is provided an excavator of the type comprising a tracked or wheeled chassis having a cab thereon, a boom pivotally mounted on a chassis and a dipper arm pivotally mounted on an end of the boom, a quick coupler being located at a distal end of the dipper arm to which is attached a bucket assembly in accordance with the first aspect of the present invention. Preferably the ram of the bucket assembly is operable from the cab of the excavator. BRIEF DESCRIPTION OF THE DRAWINGS A self-cleaning excavator bucket in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a self-cleaning excavator bucket in accordance with an embodiment of the present invention; Figure 2 is a sectional front view of the bucket of Figure 1; and Figures 3 to 5 are side sectional view on line A-A of Figure 2 showing the movement of the pusher plate of the bucket of Figure 1 between its retracted and forward positions. DETAILED DESCRIPTION OF THE DRAWINGS A self-cleaning excavator bucket 2 in accordance with the present invention is of the type adapted to be fitted to a standard hydraulic quick coupler at a distal end of an arm or dipper of an excavator (not shown), the bucket having a pair of first and second mounting pins 4,6 mounted on a rear wall 8 of the bucket 2, said mounting pins 4,6 being arranged parallel to one another and being of predetermined diameter and spacing. The pins 4,6 extend laterally across a width direction of the rear wall 8 of the bucket 2, mutually displaced along a length direction of the rear wall 8 of the bucket 2, whereby the mounting pins 4,6 are adapted to be received by first and second spaced-apart hooks or jaws of a quick coupler to couple the bucket 2 to a dipper arm of an excavator, the quick coupler including a hydraulically operated latching mechanism for locking the hooks or jaws of the quick coupler in engagement with the mounting pins of the bucket, as is well known in the art. The bucket 2 comprises a curved outer wall 10 with a front digging edge 12 adapted to cut into material to be lifted and with the outer wall 10 trailing behind the front edge 12, the bucket 2 further comprising side walls 14,16 extending from either side of the rear wall 8 and terminating at the outer wall 10 for confining the material onto the outer wall 10, the side walls 14,16 having forward digging edges 18,20 cooperating with the front digging edge 12 of the outer wall 10 to define an open mouth 22 of the bucket 2. The digging edge 12 may be reinforced and may be provided with a sharpened edge. The digging edge 12 may be replaceable when worn. Additional replaceable wear plates may be provided on outer surface if the outer wall 10. A pusher plate 24 is pivotally mounted within the bucket 2, the pusher plate 24 having lateral side edges shaped to follow an inner contour of the side walls 14,16 of the bucket 2 and an outer edge 30 dimensioned to follow an inner face of the outer wall 10 of the bucket 2. The pusher plate 24 is pivotally coupled to the first of said mounting pins 4, adjacent an outer end of the rear wall 8, such that the pusher plate 24 is pivotally moveable within the bucket 2 between a retracted position, shown in Figure 3, adjacent the rear wall 8 of the bucket 2, and an forward position, shown in Figure 5, at or adjacent the open mouth 22 of the bucket 2, to push material out of the bucket 2 when the pusher plate 24 is moved from its retracted to its forward positions. As illustrated in Figures 3 to 5, an outer edge 30 of the pusher plate 24 may be reinforced. A double acting hydraulic ram 32 is mounted within the bucket 2 having a first end pivotally coupled to second mounting pin 6 of the bucket 2, adjacent a rear end of the rear wall 8, and a second end pivotally coupled to a rear face of the pusher plate 24, adjacent said outer edge 30 thereof, such that extension and retraction of the ram 32 moves the pusher plate between its retracted and forward positions. By pivotally coupling the pusher plate 24 and the ram 32 to the mounting pins 4,6 of the bucket 2, the space taken up within the bucket 2 by the pusher plate 24 and ram 32, when the pusher plate is in its retracted position, is minimised. As best shown in Figure 1, the pusher plate 24 is pivotally mounted on the first mounting pin 4 via a respective pair of spaced mounting flanges 40,42 respectively located at either end of the first mounting pin 4. The ram 32 is pivotally mounted on the second mounting pin 6 via a respective pair of spaced mounting flanges 44,46 respectively located at either end of the second mounting pin 6. Preferably the pusher plate 24 is mounted forwardly of the pivot axis of the first mounting pin 8 by virtue of the shape of the mounting flanges 40,42. Preferably the outer wall 10 of the bucket 2 has a constant radius centred on the first mounting pin 6, such that the outer edge 30 of the pusher plate 24 remains close to or in sliding contact within the inner face of the outer wall 10 of the bucket 2. As shown in Figures 1 and 2, the side walls 14,16 of the bucket 2 preferably converge towards one another in the direction of the outer wall 10, allowing the bucket 2 to remain narrow for trench digging while allowing the pusher plate 24 and ram 32 to be pivotally coupled to the first and second mounting pins 4,6 without interfering with the engagement of the jaws or hooks of a quick coupler with the mounting pins. The forward digging edges 18,20 of the side walls 14,16 may be reinforced. Preferably the rear wall 8 of the bucket 2 incorporates an opening 15 to allow passage of the ram therethrough. Such opening 15 allow material to escape from a rear end of the bucket to prevent material from jamming between a rear side of the pusher plate 24 and the rear wall 8 of the bucket 2. 5 A portion of the bucket 2 between the outer wall 10 and rear wall 8 preferably defined an opening 15 defined by truncated rear portions of the outer and side walls 10,14,16. 10 The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention as defined by the following claims.

Claims

1. A bucket assembly for mounting on a boom of an excavator comprising:a mounting coupling for attachment to the boom, said mounting coupling comprising a pair of first and second mounting pins arranged parallel to one another and being of predetermined diameter and spacing;the bucket having an outer wall with a front digging edge to cut into material to be lifted and with the outer wall trailing behind the front digging edge;the bucket having side walls for confining the material onto the outer wall;a rear wall attached to the mounting coupling;and a pivotal pusher plate being mounted on the bucket for pivotal movement about an axis transverse to the bucket at so as to be movable from a retracted position at the rear wall to a forward position in which the pusher plate moves forwardly relative to the outer wall to push material from the outer wall for discharge; wherein the pusher plate is pivotal about a pivot axis coaxial with said first mounting pin;a ram having a first end coupled to the pusher plate for moving the pusher plate between its retracted and forward positions, wherein said ram has a second end pivotally coupled to the bucket at a pivot axis coaxial with said second mounting pin.

2. A bucket assembly as claimed in claim 1, wherein the pusher plate is pivotally mounted on the first mounting pin via a pair of spaced mounting flanges respectively located on or adjacent either end of the first mounting pin.

3. A bucket assembly as claimed in claim 1 or claim 2, wherein the second end of the ram is pivotally mounted on the second mounting pin via a pair of spaced mounting flanges respectively located on or adjacent either end of the second mounting pin.

4. A bucket assembly as claimed in any preceding claim, wherein the outer wall forms a part of a cylinder centred on an axis coaxial with the first mounting pin so that pivotal movement of the pusher plate between its retracted and forward positions causes an outer edge of the pusher plate to sweep across the outer wall and causes respective side edges of the pusher plate to sweep over the side walls of the bucket.

5. A bucket assembly as claimed in any preceding claim, wherein the side walls of the bucket converge towards one another from the rear wall towards the front digging edge of the outer wall.

6. A bucket assembly as claimed in any preceding claim, wherein the rear wall of the bucket incorporates an opening to allow passage of the ram therethrough.

7. A buck assembly as claimed in any preceding claim, wherein the ram comprises a double acting hydraulic ram.

8. A bucket assembly as claimed in any preceding claim, wherein an opening is provided at a rear side of the bucket between a rear end of the outer wall and a rear end of the rear wall.

9. An excavator of the type comprising a tracked or wheeled chassis having a cab thereon, a boom pivotally mounted on a chassis and a dipper arm pivotally mounted on an end of the boom, a quick coupler being located at a distal end of the dipper arm to which is attached a bucket assembly as claimed in any of claims 1 to 7.

10. An excavator as claimed in claim 9, wherein the ram of the bucket assembly is operable from the cab of the excavator.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:-9CLAIMS1. A bucket assembly for mounting on a boom of an excavator comprising:a mounting coupling for attachment to the boom, said mounting coupling comprising a pair of first and second mounting pins arranged parallel to one another and being of predetermined diameter and spacing;a bucket having an outer wall with a front digging edge to cut into material to be lifted and with the outer wall trailing behind the front digging edge;the bucket having side walls for confining the material onto the outer wall;a rear wall attached to the mounting coupling;and a pivotal pusher plate being mounted on the bucket for pivotal movement about an axis transverse to the bucket at so as to be movable from a retracted position at the rear wall to a forward position in which the pusher plate moves forwardly relative to the outer wall to push material from the outer wall for discharge; wherein the pusher plate is pivotal about a pivot axis coaxial with said first mounting pin;a ram having a first end coupled to the pusher plate for moving the pusher plate between its retracted and forward positions, wherein said ram has a second end pivotally coupled to the bucket at a pivot axis coaxial with said second mounting pin.

2. A bucket assembly as claimed in claim 1, wherein the pusher plate is pivotally mounted on the first mounting pin via a pair of spaced mounting flanges respectively located on or adjacent either end of the first mounting pin.

3. A bucket assembly as claimed in claim 1 or claim 2, wherein the second end of the ram is pivotally mounted on the second mounting pin via a pair of spaced mounting flanges respectively located on or adjacent either end of the second mounting pin.

4. A bucket assembly as claimed in any preceding claim, wherein the outer wall forms a part of a cylinder centred on an axis coaxial with the first mounting pin so that pivotal movement of the pusher plate between its retracted and forward positions causes an outer edge of the pusher plate to sweep across the outer wall and causes respective side edges of the pusher plate to sweep over the side walls of the bucket.

5. A bucket assembly as claimed in any preceding claim, wherein the side walls of the bucket converge towards one another from the rear wall towards the front digging edge of the outer wall.

6. A bucket assembly as claimed in any preceding claim, wherein the rear wall of the bucket incorporates an opening to allow passage of the ram therethrough.

7. A buck assembly as claimed in any preceding claim, wherein the ram comprises a double acting hydraulic ram.

8. A bucket assembly as claimed in any preceding claim, wherein an opening is provided at a rear side of the bucket between a rear end of the outer wall and a rear end of the rear wall.

9. An excavator of the type comprising a tracked or wheeled chassis having a cab thereon, a boom pivotally mounted on a chassis and a dipper arm pivotally mounted on an end of the boom, a quick coupler being located at a distal end of the dipper arm to which is attached a bucket assembly as claimed in any of claims 1 to 7.

10. An excavator as claimed in claim 9, wherein the ram of the bucket assembly is operable from the cab of the excavator.

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