Coupler for use on an Excavator Dipper Arm

Abstract

2020289732 15 Dec 2020 Editorial Note 2020289732 There are only 4 pages of Drawing 20 20 28 97 32 1 5 D ec 2 02 02020289732 15 Dec 2020

Description

Coupler for use on an Excavator Dipper Arm FIELD OF THE INVENTION This invention relates to a coupler, and in particular, but not exclusively to a quick hitch coupler for securing a range of implements and tools to the dipper arm of an excavator dipper arm. BACKGROUND Quick hitch couplers have been used to secure tools such as buckets to the dipper arms of excavators for many years. Safety concerns have led to the need for safer couplers since there have been cases where implements or tools have fallen from quick hitch couplers, resulting in injury or death. In the past decades, a range of new coupler designs have been developed and trialled in the field. There have been many developments that have been made to the design of couplers to improve safety. Some of the safety improvements have worked well, while others tend to make the couplers difficult to operate. The complexity of the safety features has sometimes resulted in a higher likelihood of a mechanical malfunction, which in turn has reduced the level of safety. Too many hydraulic lines, or separate actuators and lines to control sequenced lock actuators, can be a source of increased unreliability on couplers that typically operate in harsh environments and are subject to knocks and contamination from dirt, sand and stones. What is needed is a coupler that is simple to use in a safe manner, and which has inherent safety features that will significantly reduce the chance of an implement falling from the arm of an excavator, without introducing unnecessary layers of complexity that introduce reliability and potential safety issues themselves. In this specification unless the contrary is expressly stated, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge; or known to be relevant to an attempt to solve any problem with which this specification is concerned. OBJECT It is therefore an object of the present invention to provide a coupler which will at least go some way towards overcoming one or more of the above mentioned problems, or at least provide the public with a useful choice. STATEMENTS OF THE INVENTION Accordingly, in a first aspect, the invention may broadly be said to consist in a coupler for use on an excavator dipper arm, the coupler having: a coupler body and a slide, the coupler body being configured with guides to accommodate and control a sliding action of the slide relative to the coupler body, the coupler body having a forward facing jaw configured to capture and retain a first connecting pin of an implement, and the slide having an aft facing jaw configured to capture and retain a second connecting pin of an implement, a locking member that is movable between an extended condition and a retracted condition by the actuator and the locking member is configured to secure the first connecting pin within the forward jaw when the locking member is in the extended condition, and a linear actuator that is configured to extend and retract to move the slide relative to the coupler body, and to move the locking member to and between the locking member’s extended and retracted conditions; wherein during use of the coupler, extension of the linear actuator is assisted by two compression springs, a first compression spring and a second compression spring; the second spring having a higher spring rate when compared to the spring rate of the first spring, and the sequencing of the operation of the locking member is controlled by the difference between the spring rate of the first spring and the spring rate of the second spring. Preferably the higher spring rate of the second spring causes the linear actuator to move the locking member towards its extended condition during an initial portion of the extension of the linear actuator. Preferably the higher spring rate of the second spring causes the linear actuator to move the locking member towards its retracted condition during a final portion of the retraction of the linear actuator. Preferably the first compression spring assists extension of the linear actuator relative to the slide, and the second compression spring assists extension of the linear actuator relative to the coupler body. Preferably the actuator is coupled to the slide at a location that is at or near an aft end of the actuator. Preferably the actuator is coupled to the locking member at a location that is at or near a forward end of the actuator. Preferably a part of the locking member is situated within an entranceway of the forward jaw when the locking member is in its extended condition. Preferably the actuator includes an actuator body and an actuation rod, and the actuation rod extends from the actuator body when the actuator extends. Preferably the actuator is a hydraulic actuator having a cylinder, a piston, and an actuation rod. Preferably the second spring is situated forward of the first spring. Preferably the first spring is coupled to the actuator in such a manner that extension of the first spring causes extension of the actuator. Preferably an aft end of the first spring exerts a force that acts to extend the actuation rod out of the actuator body. Preferably an aft end of the first spring exerts a force against a surface on a washer that is coupled to a free end of the actuation rod. Preferably a forward end of the first spring exerts a force against a surface on the actuator that is situated on a forward half of the actuator body. Preferably a forward end of the second spring exerts a force against a surface of the actuator that is at or adjacent a forward end of the actuator body. Preferably an aft end of the second spring exerts a force against a surface that is fixed relative to the coupler body. Preferably the actuator is pivotally connected to the slide. Preferably the locking member is pivotally connected to the coupler body. Preferably the actuator is pivotally connected to the locking member. Preferably the coupler body includes a forward stop or stops configured to prevent forward movement of the slide past a predetermined forward travel limit of the slide relative to the coupler body. Preferably the coupler body includes slide guides in the form of opposing slots in opposing sidewalls of the coupler body. Preferably the forward stops are the forward ends of the opposing slots in the opposing sidewalls of the coupler body. Preferably the coupler body includes an aft stop or stops configured to prevent aft movement of the slide past a predetermined aft travel limit of the slide relative to the coupler body. Preferably the aft stop is in the form of an aft bulkhead of the coupler body of the coupler which is configured to prevent movement of the slide past the predetermined aft travel limit of the slide. Preferably the first spring is a coil compression spring and is situated about the actuator body. Preferably the second spring is a coil compression spring and is situated about a forward end of the actuator body. Preferably the first spring is situated about a cylinder of the hydraulic actuator. Preferably the or each hydraulic connection to the hydraulic actuator is situated at a location on the hydraulic actuator that is not covered by the first spring or the second spring. Preferably the cylinder of the hydraulic actuator includes one or more longitudinal galleries through which oil can pass to or from a rod end of the cylinder. In a second aspect, the invention may broadly be said to consist in an excavator incorporating at least one coupler substantially as specified herein. The invention may also broadly be said to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of the parts, elements or features, and where specific integers are mentioned herein which have known equivalents, such equivalents are incorporated herein as if they were individually set forth. DESCRIPTION Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: FIGURE 1 is a perspective view of a coupler according to the present invention, FIGURE 2 is a front end view of the coupler in which a cross sectional plane AA is defined, FIGURE 3 is a cross sectional view BB in which a detailed cross sectional side elevation view B is defined, FIGURE 4 is a detailed cross sectional side elevation view B with the coupler in an engaged and locked configuration, FIGURE 5 is a detailed cross sectional side elevation view B with the coupler in a partially disengaged and still locked configuration, FIGURE 6 is a detailed cross sectional side elevation view B with the coupler in an unlocked configuration and ready to fully disengage, FIGURE 7 is a front end view of the coupler in which a cross sectional plane CC is defined, and FIGURE 8 is a cross sectional underside plan view CC of the coupler showing a slide of the coupler. With reference to Figures 1 to 8, a coupler (11) according to the present invention will now be described. The coupler (11) has been designed for use on the dipper arm of an excavator. The coupler is designed to allow implements such as buckets and hammers to be changed quickly. The coupler is designed to engage with, or release, the two connecting pins of such implements, as desired by the excavator operator. The coupler (11) is hydraulically operated using hydraulic power from the excavator, and is controlled by a control switch that is accessible to the excavator operator. In the example shown, the coupler is in fact a tilt coupler, having the added ability to tilt a tool such as a bucket, relative to the dipper arm. Other versions of the coupler, that do not include the tilt capability, are also envisaged. It can be seen in the figures that the key components of the coupler (11) are a coupler body (13), a slide (15), and an actuator (17). In this example a pair of upper flanges (19) of the tilt mechanism includes bushes (21) that are used to secure the coupler to a dipper arm of an excavator. It is envisaged that in an alternative configuration, that does not include a tilt mechanism, the flanges (19) and bushes (21) would be an upper part of the coupler body (13) of the coupler (11), allowing direct attachment of the coupler body (13) to a dipper arm. The coupler body (13) includes two opposing sidewalls (23) and two opposing slide guides (25) to accommodate and control a sliding action of the slide (15) relative to the coupler body (13). In this example, the slide guides (25) are in the form of opposing slots in opposing sidewalls (23) of the coupler body (13). The coupler body (13) also includes a forward-facing jaw (27) that is configured to capture and retain a first connecting pin (29) of an implement. A lower forward part of the two opposing sidewalls (23) form an important part of the structure of the forward- facing jaw (27). An aft facing jaw (31) is a part of the slide (15), and the aft facing jaw (31) is configured to capture and retain a second connecting pin (33) of an implement. The end of the coupler (11) that contains the forward-facing jaw (27) is considered the forward end of the coupler (11) since this is the end of the coupler that faces the excavator operator. In use, and when coupling an implement to an excavator, the slide (15) will be moved to a foremost position, and then the forward jaw (27) will typically be engaged with the first connecting pin (29) of an implement. This part of the operation is easiest for the excavator operator to see. And then the slide (15) will be moved in an aft-wards direction allowing the aft jaw (31) to engage with the second connecting pin (33) of the implement. The coupler (11) may be rotated a little using the crowd action of the excavator arm, to lower the back end of the coupler (11) to help ensure that the second connecting pin (33) is engaged. Importantly, the coupler (11) has a locking member (35) that is movable between an extended condition and a retracted condition by the actuator (17). The locking member (35) is configured to secure the first connecting pin (29) within the forward jaw (27) when the locking member (35) is in its extended condition. A part of the locking member (35) is situated within an entranceway of the forward jaw (27) when the locking member (35) is in its extended condition. In this way, the locking member (35) is able to stop an implement inadvertently falling from the coupler (11) in a case where the excavator operator fails to properly engage the second connecting pin (33) in the aft jaw (31). An upper forward part of the locking member (35) is pivotally connected to the coupler body (13), and a lower part of the locking member (35) swings about this pivoting joint and in a downwards and forwards direction when the locking member (35) moves to its extended condition. Conversely, the lower part of the locking member (35) swings in a rearwards and upwards direction when the locking member (35) moves to its retracted condition. While the lower part of the locking member (35) is in its extended condition it reduces the opening width of a mouth of the forward jaw (27) to a width that is less than the diameter of the first connecting pin (29). As noted above, the coupler (11) includes an actuator (17). The actuator (17) is a linear actuator and it is configured to move the slide (15) in a linear, backwards and forwards, motion relative to the coupler body (13). The linear, backwards and forwards motion of the slide (15) is guided by the slots, or slide guides (25). The actuator (17) is also configured to move the locking member (35) to and between its extended and retracted conditions. The actuator (17) is pivotally connected or coupled to the slide (15) at a location that is at or near an aft end of the actuator (17). And the actuator (17) is pivotally connected or coupled to the locking member (35) at a location that is at or near a forward end of the actuator (17). The linear actuator (17) includes an actuator body and an actuation rod, and the actuation rod extends from the actuator body when the actuator (17) extends. In this example, the actuator (17) is a hydraulic actuator having a cylinder (41) (the said “actuator body”), a piston (43) and an actuation rod (45), and the extension of the linear actuator (17) is controlled by a flow of hydraulic oil to and from a rod end (47) and a head end (49) of the cylinder (41). The extension of the linear actuator (17) is assisted by two compression springs; a first compression spring (37) and a second compression spring (39). Conversely, it can be said that the retraction of the linear actuator (17) is resisted by the two compression springs. The first spring (37) is coupled to the actuator (17) in such a manner that extension of the first spring (37) causes extension of the actuator (17). An aft end of the first spring (37) exerts a force against a surface on a washer (51) that is coupled to a free end of the actuation rod (45), and thereby acts to extend the actuation rod (45) out of the cylinder (41). A forward end of the first spring (37) exerts a force against a surface on a first radially extending flange (53) of the cylinder (41). The first radially extending flange (53) is situated on a forward half of the cylinder (41). A forward end of the second spring (39) exerts a force against a surface on a second radially extending flange (55) of the cylinder (41). The second radially extending flange (55) is positioned at or adjacent a forward end of the cylinder (41). An aft end of the second spring (39) exerts a force against a surface that is fixed relative to the coupler body (13). In this example the second spring (39) exerts a force against a forward surface of an intermediate bulkhead (57). The intermediate bulkhead (57) spans between the two opposing sidewalls (23) of the coupler body (13) and contains a relatively large central hole through which the actuator (17) passes. This central hole is sized large enough to allow the cylinder (41) of the actuator (17) to move longitudinally and radially with respect to its own principal axis. The coupler body (13) includes forward stops (63) that are configured to prevent forward movement of the slide (15) past a predetermined forward travel limit of the slide relative to the coupler body (13). In this example, the forward stops (53) are the forward ends of the opposing slots (25) in the opposing sidewalls (23) — refer to Figure 8. The coupler body (13) also includes an aft stop (65) that is configured to prevent aft movement of the slide (15) past a predetermined aft travel limit of the slide (15) relative to the coupler body (13). The aft stop (65) is in the form of an aft bulkhead (67) of the coupler body (13) which is prevents movement of the slide (15) past the predetermined aft travel limit. The first compression spring (37) assists extension of the linear actuator (17) relative to the slide (15). And the second compression spring (39) assists extension of the linear actuator (17) relative to the coupler body (13). The second spring (39) has a higher spring rate when compared to the spring rate of the first spring (37). The sequencing of the operation of the locking member (33) is controlled by the difference between the spring rate of the first spring (37) and the spring rate of the second spring (39). The higher spring rate of the second spring (39), and the fact that this spring is fixed at one end with respect to the coupler body (13), means that the front end of the linear actuator (17) initially moves forward during an initial portion of the extension of the linear actuator (17), and in this way the linear actuator (17) moves the locking member (35) towards its extended condition. Similarly, the higher spring rate of the second spring (39) causes the linear actuator to move the locking member (35) towards its retracted condition during a final portion of the retraction of the linear actuator. During this final portion of the retraction of the linear actuator, that is the final five to ten millimetres of travel of the piston (43) within the cylinder (41) towards the closed end, or head end (49), of the cylinder (41), the slide (15) has contacted the forward stops (63) on the coupler body (13) and the slide (15) cannot move any further forward. This means that the cylinder (41) must then move aft-wards, and a little upwards, compressing the second spring (39) and moving the locking member (35) towards its retracted condition. The first spring (37) is a coil spring and is generally situated about the cylinder (41) of the actuator (17), at least when the actuation rod (45) is retracted. The second spring (39) is also a coil spring and is situated forward of the first spring (37), and is situated about the forward end, or head end, of the cylinder (41). The aft end of the second spring (39) bears against a floating flanged washer or a flanged bush (61) which fits loosely within the central hole within the intermediate bulkhead (57). An outside diameter of a cylindrical part of the flanged bush (61) is less than the inside diameter of the central hole within the intermediate bulkhead (57), allowing the flanged bush (61) to move radially with respect to the central hole. This radial movement of the flanged washer (61) relative to the intermediate bulkhead (57) allows the aft end of the second spring to move upwards when the cylinder (41) moves aft-wards, and a little upwards, when the actuator (17) is moving the locking member (35) towards its retracted condition. In this example, which describes an average size coupler (11), the outside diameter of the cylindrical part of the flanged bush (61) is in the range of three to ten millimetres less than the inside diameter of the central hole within the intermediate bulkhead (57), allowing the flanged bush (61) to float up or down by as much as three to ten millimetres when the front end of the actuator (17) moves up or down. The hydraulic connections (69) to the hydraulic actuator are situated at a location on the hydraulic actuator (17) that is in between the first and the second springs (37 and 39), and which is not covered by the first or the second springs (37 and 39). The cylinder (41) of the hydraulic actuator (17) includes a first longitudinal gallery (not shown) through which oil can pass to or from the rod end (47) of the cylinder (41). The cylinder (41) also includes a second longitudinal gallery (71) through which oil can flow to and from the head end (49) of the cylinder (41). The second longitudinal gallery (71) is intersected by a radial gallery (73) which communicates with the head end (49) of the cylinder (41). The radial galley (73) is located a short distance, approximately ten to twenty millimetres, from the closed end of the cylinder. During retraction of the hydraulic actuator (17) oil is able to exit the cylinder (41) at a relatively fast rate until the seal on the piston (43) covers the radial galley (73). During the remainder of the retraction of the hydraulic actuator (17), oil is only able to exit the cylinder (41) through a first flow restrictor valve (75). This design feature means that the slide (15) is able to retract quickly through the greater part of its travel, but the last portion of travel, for example the last five to ten percent, is slower travel. This slower travel provides a time delay before the locking member (35) moves to its retracted condition. The first flow restrictor valve (75) can be adjusted to vary the amount of restriction, and thereby vary the delay time, but a delay in the region of four seconds is considered advantageous. This time delay is helpful, as it is not uncommon for implements such as buckets to swing about their first connecting pins (29) when the aft jaw (31) is initially moved forward and the second connecting pin (33) is released. The additional few seconds allows the excavator operator to control the swinging motion before the first connecting pin (29) is released due to the retraction of the by the locking member (35). In this example, the coupler also includes a second flow restrictor valve (77) which controls the rate of flow to and from the rod end (47) of the cylinder (41) to assist in controlling the overall speed at which the slide (15) moves forwards and backwards. VARIATIONS To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting. For example, in the example described herein, the actuator (17) is connected directly to the locking member (35), but in an alternative embodiment it is envisaged that the actuator (17) could be coupled to the locking member (35) via a link member, the link member having pivoting connections at either end. Also, in the example described herein, the first spring (37) is situated aft of the second spring (39). It is envisaged that in an alternative embodiment the second spring (39) could be situated about the first spring (37), the intermediate bulkhead (57) being situated further aft. DEFINITIONS Throughout this specification the word "comprise" and variations of that word, such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps. ADVANTAGES Thus it can be seen that at least the preferred form of the invention provides a coupler which has at least the following advantages; the control of the operation of the coupler is accomplished simply using two springs of differing spring rates, the control and sequencing of the locking system is achieved even though the coupler is controlled using only a single hydraulic circuit, and the coupler has relatively few moving parts.

Claims

CLAIMS 1. A coupler for use on an excavator dipper arm, the coupler having: a coupler body and a slide, the coupler body being configured with guides to accommodate and control a sliding action of the slide relative to the coupler body, the coupler body having a forward-facing jaw configured to capture and retain a first connecting pin of an implement, and the slide having an aft facing jaw configured to capture and retain a second connecting pin of an implement, a locking member that is movable between an extended condition and a retracted condition by the actuator and the locking member is configured to secure the first connecting pin within the forward jaw when the locking member is in the extended condition, and a linear actuator that is configured to extend and retract to move the slide relative to the coupler body, and to move the locking member to and between the locking member’s extended and retracted conditions; wherein during use of the coupler, extension of the linear actuator is assisted by two compression springs, a first compression spring and a second compression spring; the second spring having a higher spring rate when compared to the spring rate of the first spring, and the sequencing of the operation of the locking member is controlled by the difference between the spring rate of the first spring and the spring rate of the second spring. 2 A coupler as claimed in claim 1, wherein the higher spring rate of the second spring causes the linear actuator to move the locking member towards its extended condition during an initial portion of the extension of the linear actuator.

3. A coupler as claimed in claim 1 or claim 2, wherein the higher spring rate of the second spring causes the linear actuator to move the locking member towards its retracted condition during a final portion of the retraction of the linear actuator. 4, A coupler as claimed in any one of claims 1 to 3, wherein the first compression spring assists extension of the linear actuator relative to the slide, and the second compression spring assists extension of the linear actuator relative to the coupler body.

5. A coupler as claimed in any one of claims 1 to 4, wherein the actuator is coupled to the slide at a location that is at or near an aft end of the actuator.

6. A coupler as claimed in any one of claims 1 to 5, wherein the actuator is coupled to the locking member at a location that is at or near a forward end of the actuator.

7. A coupler as claimed in any one of claims 1 to 6, wherein a part of the locking member is situated within an entranceway of the forward jaw when the locking member is in its extended condition.

8. A coupler as claimed in any one of claims 1 to 7, wherein the actuator includes an actuator body and an actuation rod, and the actuation rod extends from the actuator body when the actuator extends.

9. A coupler as claimed in any one of claims 1 to 8, wherein the second spring is situated forward of the first spring.

10. A coupler as claimed in any one of claims 1 to 9, wherein the first spring is coupled to the actuator in such a manner that extension of the first spring causes extension of the actuator.

11. A coupler as claimed in any one of claims 8 to 10, wherein an aft end of the first spring exerts a force that acts to extend the actuation rod out of the actuator body.

12. A coupler as claimed in claim 11, wherein an aft end of the first spring exerts a force against a surface on a washer that is coupled to a free end of the actuation rod.

13. A coupler as claimed in any one of claims 8 to 12, wherein a forward end of the first spring exerts a force against a surface on the actuator that is situated on a forward half of the actuator body.

14. A coupler as claimed in any one of claims 8 to 13, wherein a forward end of the second spring exerts a force against a surface of the actuator that is at or adjacent a forward end of the actuator body.

15. A coupler as claimed in any one of claims 1 to 14, wherein an aft end of the second spring exerts a force against a surface that is fixed relative to the coupler body.

16. A coupler as claimed in any one of claims 1 to 15, wherein the coupler body includes a forward stop or stops configured to prevent forward movement of the slide past a predetermined forward travel limit of the slide relative to the coupler body.

17. A coupler as claimed in claim 16, wherein the forward stops are the forward ends of the opposing slots in the opposing sidewalls of the coupler body.

18. A coupler as claimed in any one of claims 1 to 17, wherein the coupler body includes an aft stop or stops configured to prevent aft movement of the slide past a predetermined aft travel limit of the slide relative to the coupler body.

19. A coupler as claimed in claim 18, wherein the or each aft stop is in the form of an aft bulkhead of the coupler body of the coupler which is configured to prevent movement of the slide past the predetermined aft travel limit of the slide.

20. A coupler as claimed in any one of claims 8 to 19, wherein the first spring is a coil compression spring and is situated about the actuator body.

21. A coupler as claimed in any one of claims 8 to 20, wherein the second spring is a coil compression spring and is situated about a forward end of the actuator body.

22. An excavator incorporating at least one coupler as claimed in any one of claims 1 to 21.

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