Patent Description:
Couplers, also known as quick couplers, quick hitches or excavator couplers, for coupling accessories to the excavator arm of an excavator are well known in the art. The couplers generally comprise a top half that is connectable to an excavator arm using two attachment pins (via two pairs of holes provided for those attachment pins) and a bottom half for engaging two further attachment pins, on the accessory. In modern couplers, the bottom half typically comprises two jaws, rather than holes. Those jaws engage respective ones of those two further attachment pins of the accessory, and a closure mechanism for at least one of those jaws is provide, usually driven by a remote operable actuator, such as a screw-drive, or a hydraulic cylinder, operable from the cab of the excavator. <CIT> discloses an example of a known coupler.

A common feature of many such couplers is that one of the two jaws is usually referred to as a front jaw. Its opening (for receiving a first or front one of the two attachment pins of the accessory) is generally directed out of a first end of the coupler. This first end is commonly referred to as the front end as it is the end that is guided first onto an accessory pin. The direction that the opening faces - the forward direction - lies generally parallel to an imaginary line joining the two pairs of holes in the top half of the coupler, as used for attachment of the coupler to the end of the excavator arm. Sometimes the direction that the opening faces is angled slightly upwards from that line, perhaps by up to an angle of up to <NUM>° from parallel, but often it is nearly directly parallel to that line.

The second jaw is then usually referred to as a rear jaw, as it lies nearer the opposite, or back end of the coupler, albeit in the bottom wall of the coupler. It generally opens downwardly, i.e. in a direction that is generally perpendicular to the front jaw, or the imaginary line between the two pairs of holes in the top half of the coupler. It also may be off that perpendicular, perhaps by up to <NUM>°.

The jaws from the side of the coupler appear singular, but often the jaws are bifurcated - especially the rear jaw, as there are working mechanisms inside the coupler, and they often need to be serviceable. Commonly they are formed integrally to the body of the coupler, although they can be made of harder steel than the main body of the coupler, and joined thereto during the production of the coupler.

For the purpose of this application we refer to the rear jaw and the front jaw, even though each jaw may have more than one element.

The rear jaw commonly has a closure mechanism comprising a latching member and an actuator. For most couplers the latching member is described as a hook or a closure plate. The latching member can be slid or pivoted between a latched position and an unlatched position by using the actuator. In the latched position, the opening of rear jaw is at least partially closed by the latching member. In the unlatched position, the latching member is retracted out of the latching position so as to leave the jaw's opening as open as needed to allow the second attachment of the accessory to be located therein. This may be a full retraction to completely clear the opening of the rear jaw, or a less complete retraction wherein the opening of the jaw is only partially obscured, but less than in the extent needed for latching position for a particular accessory (different accessories may have different pin spacing, so often there is a degree of variance in the latching position during use of a coupler.

The unlatched position is both for allowing upward insertion of the second attachment pin in the rear jaw, and for allowing a previously captured attachment pin to be removed from the jaw downwardly.

The insertion or removal of the second attachment pin is usually achieved by rotating the coupler to drop or lift the rear jaw relative to the front jaw. During this process, it is best if the accessory has previously be laid on the ground so that it cannot drop off the coupler.

As indicated before, sometimes it is enough just to retract the latching member out of the way of the attachment pin, rather than all the way out of the jaw.

Secondary locking devices are also often provided for these couplers. For example, the coupler in <CIT> also features a blocking bar which is adapted to fall under the influence of gravity into a blocking position in front of the latching member - in that case a pivoting latching hook. In that blocking position, the blocking bar will resist the unlatching of the latching hook, even in response to operation of the hydraulic ram as provided for that purpose, by blocking the hook's path from its latching position into an unlatched position. The blocking bar achieves that position when the coupler is in a normal, in-use, orientation of the coupler, i.e. most non-inverted orientations.

The blocking bar is pivotally mounted about a pivot. That pivot is positioned near the front jaw. The blocking bar therefore points generally towards the rear jaw from that pivot and is balanced about that pivot such that gravity will usually urge it towards its blocking position, i.e. while the coupler is in the normal, in-use, orientation rather than upside down or partially inverted. Then, in order to unblock the latching hook (for decoupling the accessory from the coupler), either the coupler would need to be inverted or else some form of urging means would be provided for lifting the blocking bar from its blocking position into a non-blocking position. One such urging means could be a small hydraulic ram.

Due to the configuration of the elements of the various moveable components in these couplers, the latching and unlatching actions, for attaching or detaching an accessory to the coupler (on the end of an arm of an excavator), typically have to be performed using a series of predefined steps, upon which the design of the mechanisms enable cooperation with each other for the latching or unlatching processes. This is important so as to prevent inadvertent detachment, or to ensure appropriate attachment - an incorrect attachment can result in an unexpected detachment, or damage to the components of the coupler. What would be desirable, however, would be to provide a coupler, or a system involving a coupler, in which both jaws are able to secure a respective pin, but in which a more simple or fool proof set of predefined steps can be employed for the attachment and detachment procedures, but while still maintaining a safe securement and retention of an accessory, a safe detachment process, and even a safe attachment in the event of a "pin miss" on either the front jaw or a rear jaw.

According to a first aspect of the present invention there is provided an excavator coupler as defined in claim <NUM> as appended hereto. The excavator coupler comprises:.

Preferably the rear pin receiving area is a rear jaw that is open to a bottom of the coupler.

Preferably a bottom wall of the front jaw comprises a lip at its free end.

Preferably the rear pin receiving area comprises a lip at its free end.

Either or both of the lips can assist in the prevention of release of a respective first or second attachment pin from the respective jaw or pin receiving area.

The lip preferably defines an upwardly angled slope that will resist the exit of a pin from the grasp thereof.

Preferably the rear pin receiving area comprises an angled slope leading towards the free end thereof to force the second attachment pin into engagement with the rear pin receiving area when the two pins are clamped onto the coupler by the actuator.

Preferably the angled slope is combined with the lip to define a depression, or they are spaced apart enough to define a recess, into which the second attachment pin of the accessory can rest in the event of a retraction of the first closure member, out of which the accessory pin would need to lift in order to clear the lip.

Preferably the actuator is a hydraulic ram with a cylinder and piston.

Preferably the movable second pin engaging surface is part of a latch. Preferably the latch is a pivoting hook. It might be a sliding plate or jaw.

Preferably the cylinder is attached to the latch and the free end of the piston is attached to the housing of the coupler. Alternatively the free end of the piston is attached to the latch and the cylinder is attached to the housing.

Other forms of actuator, such as pneumatic or screw-drive actuators, can instead be used.

Preferably the latching hook pivots within the coupler housing around an axle.

Preferably the second closure member is pivotally mounted to the housing about a second axle. Preferably the second axle is positioned above and in front of a back wall of the front jaw. Preferably it lies in front of the attachment pin when the attachment pin is seating against the back of the front jaw.

Preferably the second closure member is sprung into a default latching position.

With the present invention, the second closure member has a range of motion either side of the default latching position.

Preferably the release arm can selectively move the second closure member to the open condition, or release it to the default position.

Preferably the first attachment pin, if allowed to hang on the second closure member, can move it to the more closed position.

Preferably the more closed position is such that a latching bar of the second closure member points to the lip of the front jaw.

The more closed condition is such that a release surface of the second closure member moves into a position beyond the reach of the release arm, whereby the release arm cannot open the second closure member until the second closure member reverts to the default latching position, or a position between that and the open condition.

Preferably when the second closure member is in the more closed condition, the release arm is located above the second closure member when fully engaged by the release member, in which position the release arm prevents opening of the second closure member.

Preferably the second closure member is biased into its default latching position by a bi-directional spring to allow the bi-directional movements of the second closure member - to either the more latched condition or the open condition.

Preferably the spring is a Rosta-type spring with an inner bar, an outer casing, each with square sections, and elastic members in the corners of the outer casing. However a conventional coil spring could likewise operate to serve that purpose.

Preferably the Rosta-type spring is such that the axle of the second closure member is rotationally fixed relative to the latching bar of the second closure member, and it forms the inner bar of the Rosta-type spring, the outer casing being rotationally fixed relative to the housing of the coupler.

Alternatively the Rosta-type spring is such that the outer casing of the Rosta-type spring is rotationally fixed relative to the latching bar of the second closure member, and the axle is rotationally fixed relative to the housing of the coupler.

Preferably the outer casing is a single piece construction.

Preferably the Rosta-spring provides approximately a <NUM>° angle of rotation between the maximum one way and the maximum the other way.

The second closure member may have flanges or surfaces thereon which interact with stop surfaces <NUM> on the coupler housing <NUM> to restrict rotational movement of this second closure member <NUM> so that it will allow degrees of rotation of perhaps no more than <NUM> to <NUM>°. In this embodiment it is about <NUM>° between fully blocking and fully open. This prevents over turning of the Rosta-type spring or over stretching of a conventional spring if instead provided.

Preferably the fully open condition for the second closure member brings the lowest edge of the second closure member substantially parallel to, and preferably flush with or higher than, the upper wall <NUM> of the front jaw.

Preferably that edge rotates down to a condition in the more closed condition that defines an angle with the upper wall of <NUM> degrees. Preferably it is <NUM> degrees in the default latching position. However, it may be a chosen angle between <NUM>° and <NUM>° from the fully open position.

Instead of <NUM>°, other angles are possible, dependent upon the amount of tortion desired to open the jaw - the deformable members provide additional resistance to torque, the more the inside rotates relative to the outside.

As for the more closed position, this might be between <NUM> and <NUM> degrees from the fully open position.

Preferably the second closure member is provided with a curved free end surface, which surface will be engaged by the first attachment pin if the first attachment pin is free to lift off the back of the front jaw into contact with the second closure member. That curved surface can serve to partially cup the attachment pin.

In the bottom wall of the front jaw there is preferably a recess for accommodating a part of the attachment pin if allowed to lift from the back of the front jaw.

Preferably the latching bar of the second closure member extends generally radially from the pivot axis thereof.

Preferably the release surface engaged by the release arm is provided on a flange of the second closure member that preferably extends substantially radially from the pivot axis of the second closure member.

Preferably a groove or recess is provided between the latching bar and the flange.

Preferably the release arm's free end is sized to loosely fit in the groove or recess to access the release surface of the flange.

Preferably the release arm clears the flange when the second closure member is in a more closed condition to access a reverse side of the flange when the second closure member is attempted to be returned to the open condition.

Preferably the front latch control component has a second arm, located behind the release member, which second arm will bear against the release member when the release arm is engaged by the reverse side of the flange, preventing lifting of the second closure member into the open condition.

Preferably the release member has a protrusion on a side thereof, which protrusion has a forward face that contacts the release arm.

It also has a rear face that contacts the second arm to prevent lifting of the second closure member into the open condition if the release arm is above the reverse side of the flange. Using a side protrusion allows the release arm to be spaced to the side of the cylinder <NUM>, as the protrusion extends sideways too.

Preferably the front latch control component is a pivotal component, which preferably is mounted on the same axis or axle as the piston, i.e. on the piston pin. Preferably the release arm, and the second arm, extend radially outward from the axis of that pivotal component.

These and other features of the present invention will now be described in further detail, purely by way of example, with reference to the accompanying drawings in which:.

Referring first of all to <FIG>, there is shown a schematic view of a coupler <NUM> in accordance with the present invention. The coupler <NUM> comprises a main housing <NUM> having a top part <NUM> and a bottom part <NUM>. In this preferred style of coupler, the top part has a pair of attachment holes <NUM> for attaching the coupler <NUM> to an excavator arm of an excavator, as is well known in the art.

The bottom part <NUM> instead has two jaws <NUM>, <NUM> with a first jaw <NUM> being positioned to be open to the front <NUM> of the coupler whereas the second jaw <NUM> is open to the bottom <NUM> of the coupler <NUM>. The second jaw is commonly referred to as the horseshoe, although it can have different shapes, including a narrower opening, a wider opening or a single side - for a more variable accessory capacity, as this is a rear pin receiving area and a rear attachment pin <NUM> may be at a wider or narrower spacing from a first attachment pin <NUM> of the accessory, dependent upon the size or manufacturer of the accessory. Any given accessory, however, will generally have a fixed pin spacing, whereby a coupler can be sized to accommodate a range of accessory sizes, or just a few accessories of a given pin arrangement, if the rear jaw is narrower.

The illustrated rear jaw <NUM> is wider than it is deep, to offer a wide range of accessory compatibilities, whereas the first or front jaw <NUM> is deeper than it is wide to offer a deeper securement of the first attachment pin <NUM> therein.

As illustrated, the rear jaw is preferred to be at least 2x the depth (i.e. height) of the jaw <NUM> at its deepest part.

The coupler <NUM> also includes a first latching member <NUM>, a second latching member <NUM> and a hydraulic ram or cylinder <NUM>. The hydraulic ram or cylinder <NUM> is commonly referred to as the actuator. Other forms of actuator, such as pneumatic or screw-drive actuators, can instead be used.

The first latching member <NUM> is for latching the second attachment pin <NUM> in the rear jaw <NUM>, whereas the second latching member <NUM> is for latching the first attachment pin <NUM> in the first jaw <NUM>. The hydraulic cylinder <NUM>, hydraulic lines for which are conventional in the art but not shown, is for powering the movement of the first latching member <NUM>, which in this embodiment pivots within the coupler housing <NUM> around an axle <NUM> between a latched condition, such as that shown in <FIG>, in which the first latching member <NUM> secures the second attachment pin, to a release condition, in which the latching member <NUM> is pulled away from that second attachment pin to open the rear jaw, as shown in <FIG> and <FIG>. In this embodiment this is achieved by rotating the latching member <NUM> in a direction such that the bottom part moves towards the front of the coupler <NUM>.

The coupler also includes a pivot pin <NUM> for the second latching member <NUM> for pivotally mounting the second latching member <NUM> above and in front of the seating position for the first attachment pin <NUM>. The second latching member thus likewise has a fixed axis relative to the coupler housing <NUM>.

A piston pin <NUM> is also provided, extending between opposing side walls of the coupler, generally parallel to the two attachment pins <NUM>, <NUM>, for pivotally mounting a distal end of the piston <NUM> of the hydraulic cylinder <NUM> in the coupler housing <NUM>. The head <NUM> of the cylinder <NUM> is then pivotally attached to the first latching member <NUM> by one or more pins <NUM>, whereupon the hydraulic cylinder can move the first latching member - in this case a latching hook. In an alternative embodiment, the cylinder and piston may be reversed so that the head <NUM> of the cylinder <NUM> is fixed to the housing <NUM> and the distal end of the piston <NUM> is instead mounted on the first latching member <NUM>.

The actuator, and in this example the cylinder <NUM>, has a front latch actuating member <NUM> extending in a forward direction therefrom. That front latch actuating member <NUM> is provided for interaction with the second latching member <NUM> - in this embodiment indirectly. In this embodiment, this is achieved by the free end of the front latch actuating member <NUM> engaging a release arm <NUM>, which in turn interacts with the second latching member <NUM>. For this purpose there is a flange <NUM> provided on the second latching member <NUM>, which flange has a release surface <NUM> that can be contacted by the release arm <NUM> when the second latching member is in any position between a default latching position, as per <FIG>, and an open condition, as per <FIG>, continual movement of the front latch actuating member <NUM> in a forward direction <NUM> relative to the housing <NUM>, after contact with the release arm <NUM>, causing such contact between the release arm <NUM> and the release surface <NUM> to occur and then a resultant movement of the second latching member <NUM> from its default latching position to the open condition due to the bias of the release arm <NUM> on the release surface of the second latching member <NUM>.

The second latching member can also move from the default latching position of <FIG> in an opposite direction towards a more closed condition, as per <FIG>. In that more closed condition, where the free end at the bottom thereof moves forwards, the release surface <NUM> moves into a position beyond the reach of the release arm <NUM> (wherein below its line of movement), whereby the release arm <NUM> can no longer interact with the release surface <NUM> of the flange to move the second latching member <NUM> to the open condition. Instead, upon the continued movement of the front latch actuating member <NUM> into the position in which it would have opened the second latching member <NUM>, the release arm <NUM> now instead puts its eng at a position that lies over the flange <NUM>, the reverse side <NUM> of which flange being now a latch retention surface <NUM>. The front latch actuating member <NUM> thus instead moves the release arm <NUM> into a condition in which it locks the second latching member <NUM> in a position below the open condition, such as its default latching or more closed condition - the release arm will be prevented from rotating or moving further upwards, thus providing the locking function, either by a stop on the housing, or as shown by a second arm <NUM> on the pivotal component <NUM> that has the release arm <NUM> that instead would be stopped from such further rotation.

In order to default the second latching member <NUM> into its default latching position, it is provided with a spring to provide a biasing force there into. This will be a bi-directional spring to allow the bi-directional movements of the second latching member - to either the more latched condition or the open condition.

In this embodiment the second latching member is pivotally mounted about its axle <NUM>. The spring biases the second latching member <NUM> such that it defaults under the forces of the spring into the default latching position in which it partially extends across the mouth <NUM> of the front jaw <NUM>. The spring in this preferred embodiment is a Rosta-type spring. However a conventional coil spring could likewise be provided to serve that purpose, for example by being connected to the housing at one end and to a flange of the second latching member <NUM> at the other. The Rosta-type spring, however, provides a compact solution. It will be described in greater detail below with reference to <FIG>.

A free end <NUM> of the second latching member <NUM> is arranged so that should the first attachment pin <NUM> be attempted to be removed from its seat at the back <NUM> of the front jaw <NUM>, it will eventually engage the second latching member, upon which the second latching member <NUM> will tend to be rotated into (or towards) the more closed condition of <FIG>.

As known in the art, the second latching member may have flanges or surfaces thereon which interact with stop surfaces <NUM> on the coupler housing <NUM> to restrict rotational movement of this second latching member <NUM> so that it will allow degrees of rotation of perhaps no more than <NUM> to <NUM>°. In this embodiment it is about <NUM>° between fully blocking and fully open - fully open bringing the lowest edge of the second latching member substantially parallel to the upper wall <NUM> of the front jaw, and the more closed condition having that surface instead at about <NUM>° from that upper wall <NUM>. Its default rest position, however, may be a chosen angle between <NUM>° and <NUM>° from the fully open position. As shown, it is about <NUM> degrees. As for the more closed position, this might be between <NUM> and <NUM> degrees.

As shown in <FIG>, the second latching member is provided with a curved free end surface <NUM>, which surface is engaged by the first attachment pin <NUM> when the second latching member <NUM> is being moved from its default position into the more closed position. That curved surface can serve to reduce or remove the requirement of one of the stops <NUM> - by partially cupping the attachment pin, a condition can be achieved where there is a two-point contact between the attachment pin and the free end surface <NUM>, or such that the cup starts to jam against the attachment pin as the cup provides a varying interface angle with the pin. In that jammed condition, further downward rotation of the second latching member <NUM> would be prevented. This would generally occur if the coupler and accessory was inverted such that the pin sits against and is loaded upon the upper wall <NUM> of the front jaw. That thus provides a secure blocking of the exit of the first attachment pin <NUM> out of the front jaw.

In <FIG>, however, the coupler is not inverted and thus the first attachment pin <NUM> sits on a lower part of the front jaw <NUM>. In that lower part, this embodiment has a recess <NUM>, sized to accommodate a part of the attachment pin <NUM> - preferably with at least a two-point contact. This recess terminates at or before a lip <NUM> near the free end of that lower part of the jaw <NUM>. This recess and lip will work with the second latching member's free end <NUM> to contain the first attachment pin within the recess because the cupped portion pushes the pin <NUM> down into that recess <NUM> if the first pin continues to press against the latching member and the lip.

The cupped portion <NUM> pushing that attachment pin <NUM> into the recess <NUM> is shown in <FIG>. With this arrangement, the pin <NUM> cannot exit the front jaw <NUM>, and the lip caries much of the force from the pin.

In addition to the cupped portion <NUM>, the second latching member <NUM> comprises a body for housing the axle <NUM> and the Rosta-type spring as discussed below, with the body featuring the first flange for providing the release surface <NUM> and a second flange for providing a latching bar of the front jaw. In this embodiment the latching bar extends generally radially from the body with respect to the axle <NUM>. The first flange <NUM> likewise extends generally radially from that body. Between them they provide a groove or recess <NUM> therebetween. In use, the release arm <NUM> will enter into that groove or recess <NUM> when lifting the second latching member <NUM> into the open condition as shown in <FIG>, but will fall out of that groove or recess <NUM> when the cylinder <NUM> extends its piston <NUM> to move the first latching member rearwardly. It thus can then instead pass over the original flange <NUM> when the latching bar is instead first moved by the first attachment pin of the accessory into its more closed condition. As the release arm <NUM> passes over the original flange <NUM>, the release arm moves into a position over the top of that original flange <NUM> for instead selectively engaging with the latch retention surface on the reverse side <NUM> of the original flange <NUM> in the event that the second latching member <NUM> was attempted to be re-opened again, until such a time that the actuator once again re-extends the piston <NUM> out from the cylinder <NUM> (which then returns the release arm <NUM> to a position rearward of that original flange <NUM>.

As for the cupped portion <NUM>, it is formed by a rearward edge of a further flange <NUM>, extending at the sides of, but between, the original flange <NUM>, with the release surface, and the second flange with the latching bar and free end <NUM>.

As for the actuating member <NUM> on the cylinder <NUM>, it comprises a forward facing finger. To the side of that finger is a protrusion <NUM>, which protrusion <NUM> has a forward face that contacts the release arm <NUM>. This allows the release arm <NUM> to be spaced to the side of the cylinder <NUM>, as the protrusion extends sideways too.

In this embodiment the release arm <NUM> is part of a pivotal component <NUM>, which pivotal component <NUM> is mounted on the same axis as the piston pin <NUM>. For this purpose, the same axle pin <NUM> may be used. The pivotal component <NUM> has the release arm <NUM> extending substantially radially outward therefrom and has circumferentially spaced therefrom a second arm <NUM>. Between the release arm <NUM> and the second arm <NUM> is a further recess or groove within which the protrusion <NUM> will fit during engagement of the release arm <NUM> with the release surface <NUM> and during positioning of the release arm <NUM> above the first flange <NUM>, as shown in <FIG>. Upon extension of the piston <NUM> out of the cylinder <NUM>, however, the protrusion <NUM> exits that further groove or recess, thus allowing free rotation of the pivotal component <NUM>.

That pivotal component <NUM> could alternatively be sprung biased into a default condition with the release arm <NUM> positioned out of the groove or recess <NUM> of the second latching member, which in this embodiment is a downwardly hanging position.

Preferably the release arm <NUM> has a lip for engaging the release surface.

The second arm, by being behind the protrusion <NUM> when the protrusion is engaging the release arm <NUM>, will serve to prevent over rotation of the pivotal component <NUM> upon inversion of the coupler, or during opening of the second latching member when the release arm has been moved to the position above the second latching member by the actuating member <NUM> or protrusion <NUM>.

Referring next to <FIG>, the first attachment pin <NUM> has moved forwards from the back <NUM> of the front jaw <NUM>. Further, the piston <NUM> has retracted further into the cylinder, whereby the latching hook <NUM> has released the rear attachment pin. In this situation the accessory is still secured onto the coupler by the front jaw, whereby it won't fall off the coupler. As this situation is undesireable, <FIG> illustrate further optional features of this coupler designed to avoid this situation. They are discussed further below.

In the coupler of <FIG>, the maximum retraction of the piston <NUM> into the cylinder <NUM> pulls the first latching member clear of the rear jaw <NUM>, as shown in <FIG>. Alternative embodiments may only allow it to pull less far, perhaps with the length of the piston or cylinder being longer, or the coupler shorter. In preferred embodiments, the front jaw's latching mechanism still functions as described. In such embodiments, the first latching member will still partially close the opening of the rear jaw even when fully retracted. However, it should pull far enough forwards to release the second attachment pin of any accessory intended to be used with the coupler. Such an arrangement is typically compatible with fewer accessories.

Referring next to <FIG>, the Rosta-type spring is further described.

The axle <NUM> of the second latching member is provided with a square section <NUM> along a part of its length. As shown in <FIG>, this is a part that is distal of a flanged end <NUM>. Proximal of the square section, i.e. closer to the flanged end, is a round section having a diameter approximately equal to the diagonal length of the square section <NUM>, which round section ends at the flanged end.

The flanged end has flattened side portions such that it can be turned with a tool. It will fit in a recess in the sidewall of the coupler, or in a bushing there within, such that the pin will rotate relative to the housing.

The distal end <NUM> of the axle <NUM> is instead provided with a stub with a circular diameter smaller than the square width of the square section <NUM> so that the axle <NUM> can be inserted through the rest of the Rosta spring components with the square section <NUM> being an operable part within the Rosta spring, as discussed below. The distal end <NUM> will pass through the other side of the housing such that the axle entends through both sides of the housing.

The distal end <NUM> has a groove near its free end for a circlip for holding the axle at the other side of the housing - shown here within a bushing <NUM>. The axle is this fixed between the two sides of the housing <NUM>.

Mounted upon the square section is the second latching member <NUM>, with a bifurcated body form, from which the flange <NUM> and the latching arm with the free end <NUM> extend. They two ends of the biforcated body form respectively have a round hole at one end and a square hole at the other, such that the round hole sits on the round section part of the axle, proximal to the square section of the axle, and the square section on the square section of the axle. The axles is thus rotatably fixed to the body form.

Between the two ends, however, is a square outer frame <NUM> and a square inner frame <NUM> of the Rosta-type spring. Between the two frames are four rubber inserts <NUM>, each one in a respective corner of the outer frame <NUM>.

The outer frame is rotated <NUM>° relative to the inner frame such that the corner gaps internal of the outer frame and external of the inner frame can be mostly filled with the rubber inserts <NUM>. The rubber inserts <NUM>, by being in the corner gaps between the frames, then compress against the flat sides of the inner square frame and against the corner or two side intersecting walls of the outer frame to provide a default <NUM>° position for the inner frame relative to the outer frame. That in turn provides the required default latching condition for the second latching member as the inner square frame is a tight fit on the square section of the axle.

Angles other than <NUM> may be provided by having differently shaped rubber inserts.

Due to the non-infinite compressibility of the inserts, the Rosta-type spring will allow rotations, without breaking the Rosta-type spring, or angles up to perhaps between <NUM>-<NUM> degrees either side of the default position. Preferably the range of movements is up to <NUM> degrees either side of centre.

The provision of the inner frame is non essential as the axle can instead provide that function directly. However, assembly is easier when the Rosta-type spring is preformed ith the inner and outer frames with the square hole in the inner frame for receiving the axle.

To hold the square outer frame in a fixed orientation relative to the coupler's housing <NUM>, that square frame <NUM> will be located in a recess of the housing <NUM>, or otherwise fixed thereto.

The structure of the Rosta-type spring allows a certain degree of rotation of the inner frame relative to the outer frame - typically up to <NUM>° either way by compressing the rubber elements, as shown in <FIG>. The second latching member <NUM> can thus rotate through the illustrated <NUM> degrees either way.

Instead of the outer frame being a square tube, it could be formed as three sides attached to a flat face of housing <NUM>.

As illustrated, the Rosta-type arrangement of the bi-directional spring allows rotation of the inner square frame relative to the outer square frame by compression and shearing of the rubber elements, which compression and shearing creates a return biasing force to return the square section to its original or default condition. In the present invention, this original condition is the default latching condition as shown in <FIG>.

Referring next to <FIG>, various methods of providing a bias for the cylinder/piston is shown - arranged to bias the piston into an extended position relative to the cylinder.

In <FIG>, a sprung driver or biasing mechanism is provided internal of the piston <NUM>. Various solutions for that are illustrated. A first solution is shown in <FIG>, wherein a pneumatic back-up piston is provided internal of the actuator's piston <NUM>, wherein the end of the actuator's piston <NUM> that is internal of the cylinder <NUM> has a bore <NUM> drilled therein for receiving a pneumatic gas spring or piston <NUM>. The pneumatic gas spring or piston comprises a casing <NUM> and a rod <NUM>, which rod <NUM> can extend between an extended condition as shown in <FIG> and a contracted condition as shown in <FIG>.

Although a pneumatic piston is illustrated, other forms of sprung driver or biasing mechanism can be used, such as a coil spring, or a compressive material spring, such as a rubber spring. Preferably it achieves a return force upon compression of the component or material device shape within it, be that a coil spring or a compressive gas, fluid or solid. Preferred is a pneumatic piston with the movable rod.

In the contracted condition of <FIG>, the rod <NUM> has been contracted into the void <NUM> as shown in black in <FIG>, thus compressing the gas therein and creating a biasing force to counter the compression of the piston <NUM> into the cylinder <NUM>.

In this embodiment, to allow for a shorter gas spring <NUM>, the void <NUM> extends into the head <NUM> of the cylinder <NUM>.

The void <NUM> contains air or gas under pressure to provide the pneumatic spring force. As such, the contracted condition of <FIG> has a higher pressure at the void <NUM> than the expanded condition of <FIG>. Likewise the free-space in the bore, between the rod <NUM> and the walls of the bore can contain air or gas under pressure, also with the compression being higher when the rod is contracted into the casing <NUM>. <FIG> is thus the default condition for the rod <NUM>, whereby the actuator is biased by the gas spring to default to an extended condition, i.e. with the piston <NUM> extended out of the cylinder <NUM>, thus helping to prevent release of an accessory in the event of a failure of the cylinder <NUM> as the extended condition locks the attachment pins of the accessory in the jaws of the coupler.

In this first embodiment, the casing <NUM> is attached to the head <NUM> of the cylinder <NUM>. Therefore, it will slide within the bore <NUM> of the piston <NUM>. A seal <NUM> is provided at the distal end of the piston <NUM> to seal between the casing <NUM> and the bore <NUM> of the piston <NUM>. This prevents the hydraulic fluid of the cylinder <NUM> entering the space between the casing <NUM> and the piston <NUM>, during normal use of the actuator. It also prevents that hydraulic fluid entering the free space between rod <NUM> and the bore <NUM>. This avoids a locking out of the gas spring (as hydraulic fluid is non-compressible). Likewise it prevents the air or gas in the free space of the bore, around the rod, from entering the hydraulic fluid, thus preventing softening of the hydraulic forces of the actuator (as entrained air in hydraulic fluid makes the hydraulic fluid part-compressible).

Referring next to <FIG>, an alternative arrangement is provided, albeit with similar benefits. In this second version, the pneumatic gas spring is reversed such that the casing <NUM> is instead mounted in the bore of the piston <NUM> and the rod <NUM> is instead attached to the head <NUM> of the cylinder <NUM>. With this arrangement, a protective sleeve <NUM> is provided, into which the casing <NUM> can slide as the rod <NUM> contracts into the casing <NUM>, as shown in <FIG>. A seal is again provided at the end face of the piston <NUM> to prevent hydraulic fluid from entering the bore, and the air or gas of the bore from entering the hydraulic fluid. However, a further seal <NUM> is provided at the end of the protective sleeve <NUM> for sealing against the casing <NUM>. This allows the space around the casing to switch between a single free space and two closed spaces, and it further provides support for the casing as the rod compresses into the casing, thus resisting buckling of the rod/casing.

In an alternative arrangement, the protective sleeve <NUM> is made longer such that the casing <NUM> is always nosed into the protective sleeve <NUM>, such that the space around the casing is always separate to the space around the rod.

A benefit from the provision of the protective sleeves <NUM> is that there is an additional radius to the gas spring arrangement, whereby the protective sleeve provides additional bending stiffness, and thus buckle resistance to the gas spring. Previously the rod could be subject to buckling, especially where it enters the casing.

Referring then to <FIG>, a third integrated gas spring is illustrated wherein the casing <NUM> is again internal to the piston <NUM>. However, the rod is instead wider, and the protective sleeve is not present. Yet further, the rod <NUM> now terminates against the head of the cylinder, rather than being attached into it.

Rather than providing a casing <NUM> in a bore of the piston, as shown, it would instead be possible to have the rod in a bore of the piston, whereby the piston itself provides the function of the casing. The casing would thus effectively be defunct, or considered integrated with the piston.

In this third illustrated embodiment, the pressurised void <NUM> is connected with a tube <NUM> near the pivotally mounted end of the piston <NUM>, with a threaded stop or cork <NUM> closing a side vent <NUM> for that tube <NUM>. With this arrangement, the pressure of the air or gas in the pressurised void <NUM> can be re-compressed or recharged in the event of pressure loss. It can also be flushed if needed.

Such a recharge port could likewise be provided for the embodiment of <FIG>.

The head could likewise comprise a recharging vent for accessing the void <NUM> in the embodiment of <FIG>.

Referring finally to <FIG>, an alternative arrangement is shown wherein the gas spring is instead mounted external and to a side of the cylinder <NUM>, in a side structure <NUM>. The side structure can be specifically for the gas spring, or it can be part of a moulding around the cylinder from which the actuating member <NUM> extends.

The side structure <NUM> has a cavity therein containing the gas spring as shown. There is again a protective sleeve <NUM>, but this time it is merely to provide protection for the rod <NUM> as by being external of the piston, it would otherwise be subject to exposure of the working environment of the coupler. It is no longer exposedto the hydraulics in the cylinder.

In this arrangement, the gas spring <NUM> can operate to drive the rod <NUM> and the protective sleeve <NUM> between a contracted position of <FIG> and an extended position of <FIG>, the extended configuration being the default configuration.

The end of the rod or protective sleeve <NUM> can be attached to a further flange <NUM> extending radially from the piston pin <NUM>, which further flange <NUM> can have a pivotal connection <NUM> to the rod <NUM> or protective sleeve <NUM>. By being pivotal, the rod can rotate with the piston as the pivotal latching hook moves. Alternatively the further flange will rotate relative to the piston pin <NUM>. For a sliding latch, the connection might instead be fixed, rather than pivotal, as the actuator would not have a need to pivot.

Usually the external gas spring will be located below the cylinder. This has two benefits. Firstly, as space is limited to the sides of the cylinder, putting it below the cylinder does not further fill the side spaces. Secondly, by being below the cylinder, it will not be as exposed to the external elements during use of an accessory (once an accessory is attached to the coupler) as the accessory will close the bottom of the coupler.

With these gas sprung mechanisms inside or outside the piston of the cylinder <NUM>, the cylinder <NUM> and the piston <NUM> will default into a condition such that the first latching hook is in a latching condition in the event of a failure of the hydraulics system of the cylinder <NUM>, or the cylinder itself, albeit not with the usual retention force of the hydraulics. Nevertheless, it will allow an operator to maintain safe retention of an accessory, after noticing a relaxation of the securement of the accessory, for long enough for him to lower the accessory to the floor.

The present invention therefore enables an accessory attached to the coupler to be releasable only by following a proper procedure, as per <FIG> - it cannot be released from the coupler in the event of an improper use of the coupler.

Claim 1:
An excavator coupler (<NUM>) comprising:
a housing (<NUM>) with a top part (<NUM>) for attachment to an excavator arm of an excavator, and a bottom part (<NUM>) for attachment to an accessory for the excavator, such as an excavator bucket, the bottom part comprising a front jaw (<NUM>) open to a front (<NUM>) of the coupler (<NUM>) for receiving a first attachment pin (<NUM>) of an accessory and a rear pin receiving area (<NUM>) open to a bottom of the coupler (<NUM>) for receiving a second attachment pin (<NUM>) of the accessory;
the coupler (<NUM>) further comprising:
a first closure mechanism for the rear pin receiving area (<NUM>), the first closure mechanism comprising an actuator (<NUM>) and a movable second pin engaging surface for selectively securing the second attachment pin (<NUM>) in the rear pin receiving area (<NUM>) and for pulling the first attachment pin (<NUM>) into the front jaw (<NUM>) of the coupler (<NUM>);
an axle pin (<NUM>) defining an axis, the axle pin (<NUM>) extending between opposing side walls of the coupler (<NUM>), generally parallel to the first and second attachment pins (<NUM>, <NUM>), for pivotally mounting a distal end of the actuator (<NUM>) in the housing (<NUM>) on the axis;
a second closure member (<NUM>) for the front jaw (<NUM>) for selectively retaining the first attachment pin (<NUM>) in the front jaw (<NUM>); and
a front latch control component for selectively controlling the second closure member (<NUM>) between an open state and a closed state, the front latch control component being a pivotal component mounted on the axis;
wherein the actuator (<NUM>) comprises a release member (<NUM>) for selectively engaging a release arm (<NUM>) on the front latch control component to activate or deactivate the front latch control component and
the second closure member (<NUM>) has a more closed condition wherein a release surface (<NUM>) of the second closure member (<NUM>) moves into a position beyond the reach of the release arm (<NUM>).