A quick coupler with a safety mechanism

Abstract

A coupler for engaging and securing an attachment to an earth working machine, comprising a coupler body that presents a receptacle into which an attachment pin can locate. A retainer is able to be moved between a retracted condition and an extended condition that prevents the pin from leaving the receptacle. A spring biased lever arm is rotatably secured to the housing at a fulcrum and is operatively connected to the retainer over at least a part of its stroke length to bias the retainer towards its extended condition.

Description

[0001] A QUICK COUPLER WITH A SAFETY MECHANISM

[0002] TECHNICAL FIELD

[0003] The present invention relates to a quick coupler with a safety mechanism. In particular although not solely the present invention may be a quick coupler for a pin-grab attachment able to selectively latch onto the attachment wherein a safety mechanism is provided to prevent un-desired detachment of the attachment to the quick coupler.

[0004] BACKGROUND

[0005] Quick couplers are used to quickly engage or disengage an attachment such as for example a bucket to an excavator. The quick coupler may be attached to the end of an excavator arm. A quick coupler may permit the operator of a machine to engage and disengage attachments without them needing to move from the cab or operating position of the excavator. An attachment lying on ground can be connected by the operator by manoeuvring the arm of the excavator to couple with the attachment. No other assistance is needed to manoeuvre the attachment to achieve a coupling, hence being "quick" to achieve a coupling.

[0006] Quick couplers need to be able to safely hold their attachments particularly because the attachments can be heavy and carry large loads. An error in establishing and maintaining a safe coupling can result in a fatal accident or damage occurring.

[0007] Quick couplers generally comprise a first locking region (typically a pair of locks), and a second locking region (typically a pair of locks). The first locking region may be a latch or hooking mechanism utilising spring loaded parts to retain a first point on the attachment. The second locking region may comprise of a portion that can move such as a wedge that is able to be actuated by the operator to lock and release a second pin of the attachment to the quick coupler.

[0008] Excavators traditionally come supplied with a hydraulic delivery and return line and a hydraulic 4 / 2 valve for servicing hydraulic components at the end of an arm. Such may be used by a hydraulic ram of the quick coupler to actuate the first locking region and the second locking region to engage and / or disengage one or both pins. Due to the fact that the second locking regions are designed to move, it is important for the safety of the quick coupler that the second locking region is purposefully retained in a locked condition when actuated to do so, even if its actuating mechanism fails such as if there is a loss of hydraulic pressure. Some mechanisms utilised for this include, but are not limited to, lead screw mechanisms, or springloaded pins. Lead screws naturally resist axial translation unless driven, and shear pins engage with a corresponding feature of the moving locking part and are loaded in shear to fix the locking part. Shear pins are a type of mechanism that also has to be actuated to disengage to subsequently move the second locking region, resulting in a more complicated process of actuating the locking mechanisms. Lead screws combine the actuation and fixing of the second locking region into a single mechanism, however, lead screws require more accompanying parts such as bearings and are also prone to more maintenance as they have exposed threads which may be damaged or accrue debris.

[0009] Consequently, therein exists a need for a safety mechanism for the second locking region of a quick coupler to achieve a fixing mechanism that resists motion of the second locking region when a primary actuator fails, but does not rely on being actively powered to disengage the mechanism to allow the second locking region to be intentionally move.

[0010] It is therefore an object of the present invention to provide quick coupler with a safety mechanism that addresses at least one of the above-mentioned desiderata and disadvantages and / or that will at least provide the public with a useful choice.

[0011] SUMMARY OF THE INVENTION

[0012] In a first aspect the present invention may be said to be a coupler for engaging and securing an attachment to an earth working machine, comprising a. a coupler body that presents a receptacle comprising a mouth opening via which a pin of an attachment can pass, to move through a passage of the receptacle to a captive region of the receptacle, b. a retainer able to be moved over a stroke length by an actuator relative to the coupler body between (i) a retracted condition of the retainer that allows the pin to move into and out of the receptacle and (ii) an extended condition of the retainer that is more occluding of the passage than the retracted condition, c. a spring biased lever arm secured to the housing at a fulcrum, the lever arm at a location away from the fulcrums is operatively connected to the retainer over at least a part of its stroke length to bias the retainer towards its extended condition.

[0013] Preferably in the extended condition of the retainer the retainer at least partly occludes the passage to prevent the pin from moving out of the captive region when the attachment is fully engaged to the coupler.

[0014] Preferably the spring is operatively connected to the housing and to the lever arm to bias the retainer to its extended condition over part of the stroke length.

[0015] Preferably the lever arm is not operatively connected to the retainer to bias the retainer to its extended condition when the retainer is in its retracted condition.

[0016] Preferably the lever arm is not operatively connected to the retainer to bias the retainer to its extended condition when the retainer is in its retracted condition and at a portion of its stroke length towards its extended condition.

[0017] Preferably the lever arm is operatively connected to the retainer to bias the retainer to its extended condition when the retainer is in its extended condition and at a portion of its stroke length towards its retracted condition.

[0018] Preferably the lever arm and the retainer have a cammed interface.

[0019] Preferably the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is able to operatively engage with the cam follower to thereat apply a spring-force induced force to the cam follower to bias the retainer to its extended condition.

[0020] Preferably the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is able to operatively engage with the cam follower to thereat apply a spring-force induced force to the cam follower to bias the retainer to its extended condition.

[0021] Preferably the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is operatively engaged with the cam follower to thereat apply a spring-force induced force to the cam follower to bias the retainer to its extended condition over at least a part of its stroke length.

[0022] Preferably the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is operatively engaged with the cam follower has a cam follower surface profile to (a) allow the lever arm to apply a spring-force induced force to the cam follower to bias the retainer to its extended condition over a first part of its stroke length and (b) prevent the lever arm applying a spring-force induced force to the cam follower to bias the retainer to its extended condition over a second part of its stroke length.

[0023] Preferably the lever arm is connected to the retainer using a linkage mechanism..

[0024] Preferably the linkage mechanism comprises of a link that is pivotally connected to the lever arm at a first location and to the retainer at a second location spaced from the first location..

[0025] Preferably the link is connected to the lever arm using a first bearing and to the retainer using a second bearing.

[0026] Preferably the first part of the stroke length is when the retainer is at its extended condition and a first distance of the stroke length towards the retracted condition and the second part of the stroke length is when the retainer is at its retracted condition and a second distance of the stroke length towards the first stroke length.

[0027] Preferably over the second part of the stroke length the lever arm does not bias the retainer to its extended condition and over the first part of the stroke length the lever arm does bias the retainer to its extended condition. Preferably over the first part of the stroke length the lever arm and the actuator can move the retainer to its extended condition.

[0028] Preferably over the second part of the stroke length the actuator can move the retainer to its extended condition.

[0029] Preferably over the first part of the stroke length the lever arm and the actuator can move the retainer to its extended condition and over the second part of the stroke length the actuator can move the retainer to its extended condition.

[0030] Preferably over the first part of the stroke length the lever arm and the actuator can move the retainer to its extended condition and over the second part of the stroke length the actuator and not the lever arm can move the retainer to its extended condition.

[0031] Preferably the actuator is a linear actuator.

[0032] Preferably the actuator is a linear actuator selected form one a pneumatic ram and screw actuator.

[0033] Preferably the retainer travels in a linear manner between its retracted and extended conditions.

[0034] Preferably the actuator acts directly on the retainer.

[0035] Preferably the actuator is in a more extended condition when the retainer is in its extended condition than when retainer is in its retracted condition.

[0036] Preferably the spring acts on the lever arm intermediate of the fulcrum and where the lever arm operatively engages the retainer.

[0037] Preferably the spring acts on the lever arm on the opposite side of the fulcrum to where the lever arm operatively engages the retainer.

[0038] Preferably the spring acts on the lever arm at a location where it creates a mechanical advantage for the lever arm at where it operatively engages the retainer.

[0039] Preferably the mechanical advantage is a positive mechanical advantage.

[0040] Preferably the mechanical advantage is a negative mechanical advantage. Preferably the mechanical advantage is a positive mechanical advantage over at least one part of the stroke length and a negative mechanical advantage over at least one other part of the stroke length.

[0041] Preferably the spring exerts a greater spring force on the lever arm when the retainer is on the retracted condition than when the retainer is in the extended condition.

[0042] Preferably the lever arm is operatively connected with the retainer at a location relative the fulcrum that changes along the stroke length.

[0043] Preferably the notional lever arm distance of the lever arm acting on the retainer at changes along the stroke length.

[0044] Preferably the lever arm is operatively connected with the retainer at a location from the fulcrum that is greater when the lever arm is in its extended condition than when the retainer more proximate its retracted condition.

[0045] Preferably the notional lever arm distance of the lever arm acting on the retainer is greater when the lever arm is in its extended condition than when the retainer more proximate its retracted condition.

[0046] Preferably the lever arm applies a biasing force vector acting parallel to the direction of the stroke of the retainer that changes based on the rotational angle of the lever arm relative the body.

[0047] Preferably the spring force applied by the spring to the lever arm is applied at an angle that varies over the stroke length.

[0048] Preferably the spring acts in tension over the stroke length.

[0049] Preferably the spring force increases as the retainer travels towards the retracted condition.

[0050] Preferably the bias force applied to the retainer by the spring in not directly proportional to the spring force over the stroke length.

[0051] Preferably the spring is a helical coil spring. Preferably the spring is a helical coil spring that is more elongated when the retainer is in its retracted condition than when the retainer is in the extended condition.

[0052] Preferably the spring is part of a spring assembly that comprises a spring housing that the spring is housed in and a rod extending through the spring and between which the spring is operatively.

[0053] Preferably the one of the spring housing and rod is connected to the coupler body and the other of the spring housing and rod is connected to the lever arm.

[0054] Preferably the rod is connected to the coupler body and the spring housing is connected to the lever arm.

[0055] Preferably the retainer comprises of a wedge and cam follower presented from the wedge to allow the lever arm to operatively connect to the cam follower to apply a force to the retainer to bias it to its extended condition over at least part of the stroke length.

[0056] Preferably the spring is torsional spring.

[0057] Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realised and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended figures.

[0058] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

[0059] All patents, patent applications, published applications and publications, websites and other published materials referred to throughout the entire disclosure herein, unless noted otherwise, are incorporated by reference in their entirety. DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings, which are included to provide further understanding of the invention are incorporated and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention. In the drawings:

[0061] Figure 1A shows a side view of a quick coupler with an attachment engaged in the first lock of the quick coupler.

[0062] Figure 1 B shows a side view of a quick coupler with an attachment engaged in the first and second lock of the quick coupler.

[0063] Figure 2A shows a vehicle with a quick coupler mounted to the end of its arm, with the quick coupler carrying an attachment.

[0064] Figure 2B shows a section view of a quick coupler, wherein the quick coupler has a first and second lock mechanism that are each actuated by an actuator to retain a pin of an attachment.

[0065] Figure 2C shows a section view of a quick coupler as in Figure 2B, wherein the actuators have actuated the first and second lock mechanisms to no be retaining the pins of the attachment.

[0066] Figure 3 shows a section view of a quick coupler in a region of its second lock mechanism, with a biasing lever arm, wherein the retainer of the second lock mechanism is in a retracted condition and the biasing lever arm is not acting to bias the retainer to its extended condition.

[0067] Figure 4A shows a section view of a quick coupler in a region of its second lock mechanism, with a biasing lever arm, wherein the retainer of the second lock mechanism is in an extended condition and the biasing lever arm is engaged against the retainer to bias it towards its extended condition.

[0068] Figure 4B illustrates a force diagram of the lever arm in Figure 4A there Fsl is a force applied by a linear spring such as a coil spring.

[0069] Figure 4C illustrates a force diagram of a lever arm in Figure 4A in an alternative embodiment wherein a torsion spring is used instead of a linear spring . Figure 5A shows a section view of a quick coupler in a region of its second lock mechanism, with a biasing lever arm, wherein the retainer of the second lock mechanism is in a partially extended condition and the biasing lever arm is biasing the retainer toward the extended condition.

[0070] Figure 5B illustrates a force diagram of the lever arm in Figure 5A.

[0071] Figure 5C illustrates a force diagram of a lever arm in Figure 5A in an alternative embodiment wherein a torsion spring is used instead of a linear spring.

[0072] Figure 6 shows a perspective view of a portion of a second lock mechanism.

[0073] Figure 7 shows a section view of a portion of a second lock mechanism.

[0074] Figure 8A shows an example configuration wherein the retainer is in its fully retracted condition.

[0075] Figure 8B shows an example configuration wherein the retainer is in its fully extend condition.

[0076] Figure 8C shows a plot of retainer extension vs force applied to the retainer by the lever arm, wherein the 0% extension corresponds to the configuration shown in figure 8A and where the 100% extension corresponds to the configuration shown in figure 8B.

[0077] Figure 9A shows an example configuration of a spring applying a biasing force to extend a retainer via an operatively direct connection.

[0078] Figure 9B shows a corresponding force response over the retainer extension range of the configuration of figure 9A.

[0079] Figures 10A-C shows a different configuration wherein the lever arm and retainer are connected using a linkage mechanism and its range of motion between the extended and retracted conditions of the retainer.

[0080] DETAILED DESCRIPTION OF THE INVENTION

[0081] Referring now to figures 1A and 1 B, an example of a Quick Coupler 101 is shown to comprise a First locking region 105 and a Second locking region 106, designed such that the first locking region 105 may receive a First Mounting Pin 107 of an Attachment 102, and the Second locking region 106 may receive a Second Mounting Pin 108. The Quick Coupler 101 is shown with the Attachment 102, wherein the Attachment 102 is a digger bucket as a example. It is preferable that the Quick Coupler is compatible with a range of various attachment types, including but not limited to buckets, augers, compactors, ploughs, rakes, hammers, claws, grapples, couplers, thumb buckets, breakers, rippers, crushers, pulverisers, and pallet forks.

[0082] The Quick Coupler 101 comprises Mounting Features 103 104 such that the Quick Coupler 101 may be fastened to a vehicle or a mechanism of a vehicle allowing it to change attachments quickly, wherein traditionally an attachment would be directly or more permanently fastened to said vehicle or mechanism instead.

[0083] When coupling with the attachment, the Quick Coupler 101 is designed to engage with the Attachment 102 by firstly receiving the First Mounting Pin 107 into the First locking region 105, where the First Mounting Pin 107 may be fixed in place by a locking mechanism, retaining it in a Locked Position 109, and secondly receiving the Second Mounting Pin 108 at the Second locking region 106, where the Second Mounting Pin 108 may be held to the quick coupler by a retainer 500 that can move between a retracted condition 501a and an extended condition 501 b.

[0084] Referring now to Figures 2A to 2C, an example of a Quick Coupler 101 is shown to be mounted to the Arm 202 of an excavator Vehicle 201, where the Quick Coupler 101 has a bucket Attachment 102 mounted to the First and Second locking regions 105 106.

[0085] Figure 2B shows the First Mounting Pin 107 of the Attachment 102 retained by a First locking region Mechanism 209 in a closed position and the Second Mounting Pin 208 of the Attachment 102 retained by a Second locking region Mechanism 210 in a closed position.

[0086] Figure 2C shows the First Mounting Pin 107 positioned in the First locking region 105 of the Quick Coupler 101 and the Second Mounting Pin 108 positioned in the Second locking region 106 of the Quick Coupler 101, however, said mounting pins are in an Unretained State 211 212 due to the locking mechanisms 209 210 being actuated to be in an open position. The First locking region Mechanism 209 and the Second locking region Mechanism 210 may be re-configured by the Actuators 213 214 to transition between the open and closed positions.

[0087] The actuators used to actuate the locking mechanisms traditionally utilise hydraulics which allow easier locking and release of an attachment.

[0088] Referring now to figures 3 and 4A and 5A, an example of a portion of a quick coupler 101 focused in particular on the second locking region 106 of the quick coupler 101. The coupler body 400 defines or presents the second locking region 106 to allow for a pin 108 of the implement to move in and out of a receptacle 502.

[0089] The coupler body 400 presents the receptacle 502 in a manner having a mouth opening 503 via which the pin 108 of the attachment can pass to move through the passage 503 of the receptacle 502 to be able to become captive in a captive region 506 of the receptacle 502. The mouth opening 503 is able to be presented in a more open condition as shown in figure 3 and in a more occluded condition as shown in figure 4A by virtue of a retainer 500 that is moveably mounted relative to the coupler body.

[0090] In a preferred form the retainer 500 is mounted to the coupler body to move rectilinearly relative to the coupler body. In a preferred form the retainer is able to slide backwards and forth relative to the coupler body and to extend across at least part of the mouth opening 503 of the receptacle 502.

[0091] The retainer is able to be moved over a stroke length by an actuator 507 such as a hydraulic ram shown in part in figure 3 and 4A. The retainer is preferably directly coupled to the piston rod 508 of the actuator 507.

[0092] The actuator is able to cause the retainer to move between a retracted condition 501a as seen in figure 3 and an extended condition 501 b as seen in figures 4A and 5. In the retracted condition of the retainer, the pin 108 is able to move through the mouth opening 503. In the extended condition, the pin 108 may be prevented from moving through the mouth opening. Whilst the mouth opening may not be completely closed, the pin 108 is prevented from moving through the mouth opening 503 either when the other pin is retained at its lock or when such pin is not retained at the other lock. The locking mechanism 106 further comprises of a spring biased lever arm 510. In the examples shown in the accompanying figures the lever arm 510 is preferably mounted to the coupler body 400 in a rotational manner at a fulcrum 511. The lever arm may be mounted, utilising a rotational bearing or bearings or may be journal mounted in a manner to allow for the level 510 to rotate through a desirable arc of rotation relative to the coupler body. The lever arm at a region 511 distal to the fulcrum 511 is able to engage with the retainer 500 to apply a force to the retainer in a direction to bias the retainer to its extended condition. The lever arm 510 at its region 511 preferably is able to exert a force to the retainer to bias the retainer towards its extended condition over at least a part of the stroke length of the retainer.

[0093] By being operatively connected to the retainer 500 at a location away from the fulcrum 511, the lever arm 510 upon its rotation around the fulcrum 511 can cause the retainer 500 to move. Such movement may be resisted such as for example by the actuator 507 however when the actuator for example loses power and is not able to apply a force or a sufficient force to the retainer, over at least some of the stroke length of the retainer, the lever arm can cause the retainer to move towards its extended condition, and / or oppose movement of the retainer toward its extended condition.

[0094] When in its extended position the retainer at least partially occludes the passage to prevent the pin in the receptacle 502 from moving out of the captive region 506 at least when the attachment is fully engaged to the coupler (e.g. when the other pin is located and or locked at its respected locking mechanism).

[0095] The quick coupler may preferably be configured to receive mounting pins of varying diameter and / or spacing between said mounting pins. Accordingly, the extension of the retainer when a given mounting pin in the receptacle 502 is retained within the captive region 506 may vary depending on the diameter and / or spacing between the mounting pins.

[0096] A minimum pick-up point 701 may be used to describe a position of maximum extension of the retainer that can allow a mounting pin of the maximum diameter and / or spacing to be received into the receptacle via its mouth opening and into the captive region. Conversely, a maximum pick-up point 702 may be used to describe a position of maximum extension of the retainer that can allow a mounting pin of the minimum diameter and / or spacing to be received into the receptacle via its mouth opening and into the captive region.

[0097] It is a benefit of the present invention that the lever arm is configured to provide a biasing force of a sufficient magnitude for a range that covers the range of motion between and / or around the length of extension of the retainer relating to both the minimum pick-up point 701 and the maximum pick-up point 702. This is discussed further below in regard to Figures 8A-9B.

[0098] A spring 520 is utilized for the purposes of exerting the bias force on the retainer. The spring 520 may for example be a helical coil spring as seen in figure 7 and may form part of a spring assembly 521 that may include a rod 522 and a spring housing 523. The spring is operatively connected to the coupler body and to the lever arm 510 to bias the retainer to its extended condition over at least part of the stroke length.

[0099] The spring is preferably operatively connected at region 530 to the lever arm so as to apply the spring force to the lever arm. The region 530 is preferably intermediate of the fulcrum 511 and the region 512 that is distal to the fulcrum 511. The region 530 is not at the fulcrum but is at some distance away there from. It will be appreciated that alternative configurations of the lever arm may be provided including where the region 530 is on the opposite side of the fulcrum to the region 512. In a preferred form the lever arm is a single arm although as seen in figure 6 it may be a single arm having two sides 510A and 510B. The spring assembly may at least partially extend between the lever arm parts 510A and 510B as seen in figure 6.

[0100] In a preferred form the lever arm is not operatively connected to the retainer to bias the retainer to its extended condition when the retainer is in its retracted condition as seen in figure 3. Whilst the lever arm may still be physically connected to the retainer 500 it is preferably so connected in a manner that it does not apply a biasing force. Given that in this configuration shown in figure 3 the spring is at its most compressed during operation, acting in compression, and its spring force is at its maximum. By the lever arm being in a position where it does not apply a biasing force to the retainer, this operationally maximum spring force in not acting on the retainer to bias it to its extended position as this part of the stroke length. Although in other embodiments it may be. It is preferably not until the actuator 507 displaces the retainer from its fully retracted condition as seen in Figure 3 towards its extended position such as seen in figure 5 that the lever arm starts to be in a condition where it does start to exert the bias force on the retainer towards its extended condition. In a sense the lever arm, when the retainer is in its retracted condition, becomes inoperative on the retainer. This is preferably achieved by virtue of the lever arm and the retainer having a cammed interface. In a preferred form the retainer comprises of a cam follower 540 and the lever arm at its region 512 comprises of a cam 541 that is able to operatively engage with the cam follower 540 to there at apply a spring forced induced force to the cam follower to bias the retainer to its extended condition. In a preferred form the retainer comprises of a cam follower and the lever arm, at a location away from the fulcrum 511 comprises of a cam that is able to operatively engage with the cammed follower to thereat apply a spring force induced force to the cam follower to bias the retainer to its extended condition when the retainer is not at its fully retracted condition. At its fully retracted condition the cam does not engage with a surface of the cam follower that allows for the cam to apply a spring force induced force onto the retainer.

[0101] In other examples, it may be preferable that a tension spring is used rather than a compression spring as previously described, such that when the retainer 500 of the quick coupler 101 is in its retracted condition 501a, the tension spring is in in a fully, or otherwise peak, extension. The complete extension of the tension spring can be used to bias the retainer toward its extended condition 501 b, according to any of the relevant examples described herein, where such.

[0102] The cam follower has a surface profile that allows for the lever arm to apply a spring force induced force to the cam follower to bias the retainer to its extended position over as first part of its stroke length. The cam follower surface profile is also such as to prevent the lever arm from applying a spring force induced force to the cam follower in a direction to bias the retainer to its extended position over a second part of its stroke length. In a preferred form the first part of the stroke length is where the retainer is at its extended condition and a first distance of the stroke length towards the retracted condition. The second part of the stroke length is when the retainer is at its retracted condition and a second distance of the stroke length towards the first stroke length. Preferably over the second part of the stroke length the lever arm does not bias the retainer to its extended condition. This is seen for example in figure 3. Over the first part of the stroke length the lever arm does bias the retainer to its extended condition this is for example seen in figures 4A and 5.

[0103] The retainer 500 preferably comprises of the cam follower 540. The lever arm, at a location away from the fulcrum, comprises of the cam 541 that can operatively engage with the cammed follower. As will hereinafter be described, the cammed interface is of a shape and configuration so that the notional lever arm force that is applied by the lever arm to the retainer is able to change in distance from the fulcrum 511.

[0104] With the spring acting on the lever arm, the location at where it acts allows for the lever arm to create a mechanical advantage for the lever arm at where the lever arm operatively engages with the retainer. In preferred form the mechanical advantage is a positive mechanical advantage although in other forms the mechanical advantage may be a negative mechanical advantage. Given that the effective lever arm force by virtue of the cammed interface can change, both a positive and negative mechanical advantage may be exercised over parts of the stroke length of the retainer.

[0105] In a preferred form the spring exserts a greater spring force on the lever arm when the retainer is in the retracted condition than when the retainer is in the extended condition.

[0106] In a preferred form the lever arm is operatively connected with the retainer at a location from the fulcrum that is greater when the lever arm is in its extended condition than when the container is more proximate to its retracted condition, as illustrated in figures 4B-C and 5B-C by the location of FR.1 being at a distance, D, from the fulcrum, whereas FR2 can be seen to be at a distance D2, where D2 < D. This can be seen with reference to figures 4A and 5A. As seen in figure 4A the notional lever arm is from the fulcrum 511 is longer than in the condition shown in figure 5A. Hence by virtue of the lever arm being longer a greater force is able to be applied by the lever arm to the retainer for any given spring force that is applied to the lever arm, wherein FR2 > FR.1.

[0107] As can be seen from the drawings, particularly as illustrated in figures 4A-C and 5A-C, the spring force that is applied by the spring on the lever is applied at an angle that will vary over the stroke length. The spring force increases as the retainer travels towards the retracted condition because the spring, being a compression spring in this example, is being compressed more from its natural relaxed state, wherein FS1 < FS2 and MS1 < MS2. The perpendicular component of the spring force on the lever arm may reduce, or have a reducing factor, when a helical coil spring is used as shown, as the retainer travels towards the retracted condition, as shown with the lever arm moving by an angle 01. This can be seen in figure 5B where FS1 < FS2 but FS1, at a distance D1 from the fulcrum, is at a substantially right angle to the lever arm, while FS2, also at a distance D1 from the fulcrum, comprises a shallower angle 02 resulting in a perpendicular component force FSN that results in a lower torque than as if the spring was compressed but remained perpendicular to the lever arm. FSN may be greater or less than FS1 depending on the particular embodiment and that relationship may vary as the retainer transitions from the extended to contracted condition. Because of the geometry, the bias force applied by the retainer to the spring is not directly proportionate to the spring force over the stroke length. A spring may have a constant linear force to displacement relationship. However, the biasing force that is experienced by the retainer from the spring does not have the same linear and constant relationship given the geometry of the mechanism here in described.

[0108] Whilst in a preferred form the spring is a helical coil spring, in an alternative form a torsional spring may be used that is located about the fulcrum 511. Such a spring can be configured to have a similar effect as the helical coil spring that is described with reference to the accompanying drawings. This configuration is shown in Figures 4C and 5C wherein MS1 < MS2. Due to a torsional spring acting coincidently with the axis of rotation, the change in spring force is proportional to the change in angle of the lever arm, wherein unlike the helical coil spring, the torsional spring does not provide a force at a decreasing angle, obviating the loss of force due to a component force along a direction radial to the fulcrum.

[0109] As previously described, the lever arm 510 in the examples of the invention is intended to provide a biasing force of a sufficient magnitude for a range that covers the range of motion between and / or around the length of extension of the retainer 500 relating to both the minimum pick-up point 701 and the maximum pick-up point 702.

[0110] Referring to figures 8A,B and 9A, examples of a quick coupler and the corresponding biasing force of a biasing spring, relative to a minimum pick-up point and a maximum pick-up point is shown.

[0111] Referring to figures 8A-B, an example of a quick coupler 101 is shown to comprise a spring configured to bias the retainer 500 of the quick coupler 101 toward its retracted condition and extended condition via a lever arm 510, as described in previous examples. The retainer is shown to comprise a range of movement 703 between its retracted condition 501a and its extended condition 501 b.

[0112] Figure 8C shows a graph providing the resultant biasing force 704 applied to the retainer 500 along its percentage of extension from the retracted condition 501a to the extended condition 501 b. The biasing force at the minimum pick-up point 701, at around 36% retainer extension, is shown to be around 95% of the maximum biasing force (see 701a) applied within the range of movement 703 of the retainer 500. The biasing force at the maximum pick-up point 702, at around 79% retainer extension, is shown to be around 81% of the maximum biasing force (see 702a) applied within the range of movement 703 of the retainer 500.

[0113] Due to the use of a lever arm 510 to apply a biasing force upon the cam follower 540 of the retainer 500 at a varying angle relative to the cam follower and at a varying distance from the fulcrum 511 of the lever arm 510, the resulting biasing force 704 can be made to be substantially similar throughout the range of movement of the retainer 500 between and around its minimum pick-up point 701 and maximum pick-up point 702. The difference of the biasing force between the minimum and maximum pick-up points is only 14 points (see 701a compared to 702a). Figures 9A-B show an example of a quick coupler 101 b that comprises disadvantages compared to the preferred form of the present invention, where the retainer 500 is biased toward the extended condition 501 b directly by a spring 520 along its direction of extension, and not via a lever arm 510 as previously described.

[0114] Figure 9B shows a graph providing the resulting biasing force 704 applied to the retainer 500 the quick coupler 101 b along its percentage of extension from the retracted condition 501a to the extended condition 501 b. A base-level biasing force of 10% is provided at 0% extension to provide an initial pre-load, however it will be clear by a person skilled in the art how that may be adapted otherwise. The biasing force at the minimum pick-up point 701, at around 36% retainer extension, is shown to be around 68% of the maximum biasing force (see 701 b) applied within the range of movement 703 of the retainer 500. The biasing force at the maximum pick-up point 702, at around 79% retainer extension, is shown to be around 39% of the maximum biasing force (see 702b) applied within the range of movement 703 of the retainer 500.

[0115] Due to the linear performance of a spring, the resulting biasing force 704 of the quick coupler's 101 b spring 520 on the retainer 500 does not match that of the quick coupler 101 as shown in Figures 8A-B. The difference of the biasing force between the minimum and maximum pick-up points is 29 points (see 701 b compared to 702b), over 2 times greater than the example shown in Figures 8A-B (see 701a compared to 702a).

[0116] It should be understood, that although the relative difference of resulting biasing force between the minimum and maximum pick-up points could be reduced by providing a spring with an increased working length and using only a small portion of said working length, such a configuration would use up more space and be an inefficient use of the spring by utilising a small portion of its working length. Accordingly, it will be clear by a person skilled in the art that the present invention provides an arrangement of biasing a retainer of a quick coupler in a more efficient and safe manner.

[0117] Regarding the example shown in Figures 8A-B, and as discussed in previous examples, when the retainer 500 is in its fully retracted condition 501a, such that the spring 520 is fully compressed, relative to its operation in the quick coupler 101, the lever arm is resting on the upper surface 705 of the cam follower 540. By the lever arm 510 being in such a position, it does not apply a biasing force to the retainer to cause it to extend, and while the lever arm is in this position, movement of the retainer does not result movement of the lever arm and thus a travel of compression or expansion of the spring. This results in a delay of when the spring 520 is providing a bias of the retainer 500, such that the total available energy (relative to the area under the curve of figure 8B) is acting during the position of the retainer 500 around and between the maximum and minimum pick-up points 701 702.

[0118] Accordingly, it may be preferable, and is a benefit of the present invention, that due to the ability to reduce the operational region of the spring that relates to the position of the retainer around and between the maximum and minimum pick-up points, a spring comprising a high spring constant may be utilised to apply large biasing loads to the retainer with a small change in length. Due to the ability for the lever arm to be in opposition on the cam follower where it does not apply a biasing arm, a spring with a high spring constant but smaller working length is a feasible component to integrate, saving space.

[0119] In a preferred form the retainer comprises of a wedge 664 and the cam follower 540. The cam follower 540 is secured or integrally formed with the wedge 664 to present itself in a shape and configuration and location for the lever arm to engage therewith.

[0120] Figures 10A-C shows a variation of a coupler where the operative connection between lever arm and the retainer utilises a linkage mechanism 850. In the examples described prior, the connection between the lever arm and the retainer is a direct connection in that the lever arm is able to press onto the retainer and it has a sliding interaction as the retainer moves between its extended and retracted conditions. Such sliding can cause wear of the lever arm and / or retainer. A linkage mechanism 850 can utilise a link member or link bar 851 that at a first end 852 is connected to the lever arm and at a second end 853 away from the first end is connected directly or indirectly to the retainer. These connections may be rotational connections and may utilise ball bearings to facilitate rotation to help reduce friction. Other mechanisms to establish a direct or indirect operative connection between the lever arm and the retainer are also envisaged and will be apparent to a person skilled in the art having read this patent specification. The invention has been described with examples relevant to its current form, however, potential embodiments will include any form that is within the scope of the appended claims. It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

CLAIMS1. A coupler for engaging and securing an attachment to an earth working machine, comprising: a. a coupler body that presents a receptacle comprising a mouth opening via which a pin of an attachment can pass, to move through a passage of the receptacle to a captive region of the receptacle, b. a retainer able to be moved over a stroke length by an actuator relative to the coupler body between (i) a retracted condition of the retainer that allows the pin to move into and out of the receptacle and (ii) an extended condition of the retainer that is more occluding of the passage than the retracted condition, c. a spring biased lever arm rotatably secured to the housing at a fulcrum, the lever arm at a location away from the fulcrum is operatively connected to the retainer over at least a part of its stroke length to bias the retainer towards its extended condition.

2. A coupler as claimed in claim 1 wherein in the extended condition of the retainer, the retainer at least partly occludes the passage to prevent the pin from moving out of the captive region when the attachment is engaged and secured to the coupler.

3. A coupler as claimed in claim 1 of claim 2 wherein the spring is operatively connected to the body and to the lever arm to bias the retainer to its extended condition over at least part of the stroke length.

4. A coupler as claimed in anyone of claims 1 to 3 wherein the lever arm is not operatively connected to the retainer to bias the retainer to its extended condition when the retainer is in its retracted condition.

5. A coupler as claimed in anyone of claims 1 to 4 wherein the lever arm is not operatively connected to the retainer to bias the retainer to its extended condition when the retainer is in its retracted condition and at a portion of its stroke length towards its extended condition.

6. A coupler as claimed in anyone of claims 1 to 5 wherein the lever arm is operatively connected to the retainer to bias the retainer to its extended condition when the retainer is in its extended condition and at a portion of its stroke length towards its retracted condition.

7. A coupler as claimed in anyone of claims 1 to 6 wherein the lever arm and the retainer have a cammed interface.

8. A coupler as claimed in anyone of claims 1 to 6 wherein the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is able to operatively engage with the cam follower to thereat apply a spring-force induced force to the cam follower to bias the retainer to its extended condition.

9. A coupler as claimed in anyone of claims 1 to 8 wherein the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is able to operatively engage with the cam follower to thereat apply a spring-force induced force to the cam follower to bias the retainer to its extended condition.

10. A coupler as claimed in anyone of claims 1 to 9 wherein the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is operatively engaged with the cam follower to thereat apply a springforce induced force to the cam follower to bias the retainer to its extended condition over at least a part of its stroke length.

11. A coupler as claimed in anyone of claims 1 to 9 wherein the retainer comprises of a cam follower and the lever arm at a location away from the fulcrum comprises of a cam that is operatively engaged with the cam follower has a cam follower surface profile to (a) allow the lever arm to apply a spring-force induced force to the cam follower to bias the retainer to its extended condition over a first part of its stroke length and (b) prevent the lever arm applying a spring-force induced force to the cam follower to bias the retainer to its extended condition over a second part of its stroke length.

12. A coupler as claimed in claim 11 wherein the first part of the stroke length is when the retainer is at its extended condition and a first distance of the stroke length towards the retracted condition and the second part of the stroke length is when the retainer is at its retracted condition and a second distance of the stroke length towards the first stroke length.

13. A coupler as claimed in claim 11 or 12 wherein over the second part of the stroke length the lever arm does not bias the retainer to its extended condition and over the first part of the stroke length the lever arm does bias the retainer to its extended condition.

14. A coupler as claimed in anyone of claims 11 to 13 wherein over the first part of the stroke length the lever arm and the actuator can move the retainer to its extended condition.

15. A coupler as claimed in anyone of claims 11 to 14 wherein over the second part of the stroke length the actuator can move the retainer to its extended condition.

16. A coupler as claimed in anyone of claims 11 to 15 wherein over the first part of the stroke length the lever arm and the actuator can move the retainer to its extended condition and over the second part of the stroke length the actuator can move the retainer to its extended condition.

17. A coupler as claimed in anyone of claims 11 to 15 wherein over the first part of the stroke length the lever arm and the actuator can move the retainer to its extended condition and over the second part of the stroke length the actuator and not the lever arm can move the retainer to its extended condition.

18. A coupler as claimed in anyone of claims 1 to 17 wherein the actuator is a linear actuator.

19. A coupler as claimed in anyone of claims 1 to 18 wherein the actuator is a linear actuator selected form one a pneumatic ram and screw actuator.

20. A coupler as claimed in anyone of claims 1 to 19 wherein the retainer travels in a linear manner between its retracted and extended conditions.

21. A coupler as claimed in anyone of claims 1 to 20 wherein the actuator acts directly on the retainer.

22. A coupler as claimed in anyone of claims 1 to 21 wherein the actuator is in a more extended condition when the retainer is in its extended condition than when retainer is in its retracted condition.

23. A coupler as claimed in anyone of claims 1 to 22 wherein the spring acts on the lever arm intermediate of the fulcrum and where the lever arm operatively engages the retainer.

24. A coupler as claimed in anyone of claims 1 to 22 wherein the spring acts on the lever arm on the opposite side of the fulcrum to where the lever arm operatively engages the retainer.

25. A coupler as claimed in anyone of claims 1 to 24 wherein the spring acts on the lever arm at a location where it creates a mechanical advantage for the lever arm at where it operatively engages the retainer.

26. A coupler as claimed in claim 25 wherein the mechanical advantage is a positive mechanical advantage.

27. A coupler as claimed in claim 25 wherein the mechanical advantage is a negative mechanical advantage.

28. A coupler as claimed in claim 25 wherein the mechanical advantage is a positive mechanical advantage over at least one part of the stroke length and a negative mechanical advantage over at least one other part of the stroke length.

29. A coupler as claimed in anyone of claims 1 to 28 wherein the spring exerts a greater spring force on the lever arm when the retainer is on the retracted condition than when the retainer is in the extended condition.

30. A coupler as claimed in anyone of claims 1 to 29 wherein the lever arm is operatively connected with the retainer at a location relative the fulcrum that changes along the stroke length.

31. A coupler as claimed in anyone of claims 1 to 30 wherein the notional lever arm distance of the lever arm acting on the retainer at changes along the stroke length.

32. A coupler as claimed in anyone of claims 1 to 31 wherein the lever arm is operatively connected with the retainer at a location from the fulcrum that is greater when the lever arm is in its extended condition than when the retainer more proximate its retracted condition.

33. A coupler as claimed in anyone of claims 1 to 32 wherein the notional lever arm distance of the lever arm acting on the retainer is greater when the lever arm is in its extended condition than when the retainer more proximate its retracted condition.

34. A coupler as claimed in anyone of claims 1 to 33 wherein the lever arm applies a biasing force vector acting parallel to the direction of the stroke of the retainer that changes based on the rotational angle of the lever arm relative the body.

35. A coupler as claimed in anyone of claims 1 to 34 wherein the spring force applied by the spring to the lever arm is applied at an angle that varies over the stroke length.

36. A coupler as claimed in anyone of claims 1 to 35 wherein the spring acts in tension over the stroke length.

37. A coupler as claimed in anyone of claims 1 to 36 wherein the spring force increases as the retainer travels towards the retracted condition.

38. A coupler as claimed in anyone of claims 1 to 37 wherein the bias force applied to the retainer by the spring in not directly proportional to the spring force over the stroke length.

39. A coupler as claimed in anyone of claims 1 to 38 wherein the spring is a helical coil spring.

40. A coupler as claimed in anyone of claims 1 to 39 wherein the spring is a helical coil spring that is more elongated when the retainer is in its retracted condition than when the retainer is in the extended condition.

41. A coupler as claimed in anyone of claims 1 to 40 wherein the spring is part of a spring assembly that comprises a spring housing that the spring is housed in and a rod extending through the spring and between which the spring is operatively.

42. A coupler as claimed in claim 41 wherein the one of the spring housing and rod is connected to the coupler body and the other of the spring housing and rod is connected to the lever arm.

43. A coupler as claimed in claim 41 or 42 wherein the rod is connected to the coupler body and the spring housing is connected to the lever arm.

44. A coupler as claimed in anyone of claims 1 to 43 wherein the retainer comprises of a wedge and cam follower presented from the wedge to allow the lever arm to operatively connect to the cam follower to apply a force to the retainer to bias it to its extended condition over at least part of the stroke length.

45. A coupler as claimed in claim 1 wherein the spring is torsional spring.

Images