AU2007100292A4 - Improved Adaptor Hitch - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT Name of Applicants: Actual Inventors: Address for Service: Invention Title: Brenda Koster; Barry Koster Barry Koster CULLEN CO., Patent Trade Mark Attorneys, 239 George Street, Brisbane, Qld. 4000, Australia.

Improved Adaptor Hitch Details of Associated Provisional Applications: Australian Provisional Patent Application No. 2006901954 filed 13 April 2006 The following statement is a full description of this invention including the best method of performing it known to us: Technical Field The present invention relates generally to adaptors for connecting or attaching implements and other tools to the end of operating arms, such as adaptors of the "quickhitch" type.

In particular, the present invention is directed to adaptors which include a locking mechanism for locking the implements or tools in engagement with the adaptors.

Background Art Adaptors are used on the end of operating arms and booms of hydraulic excavators, backhoes and other earthmoving machinery to permit quick and interchangeable attachment of ground engaging tools and other implements to such arms and booms. One such adaptor, known as the "quickhitch" adaptor, comprises two sets of calliper-like latch arms which are inserted between spaced bars or bucket pins of the implement, and then opened outwardly to hook onto the bars or pins and hold the implement. Typically, one set of latch arms is operated hydraulically.

Some quickhitch adaptors have a safety locking pin which must be manually inserted into the adaptor to prevent its latch arms from inadvertently releasing the implement which is held by the adaptor. The adaptor is usually located remotely from the cab or the control panel of the host machine so that the operator of the machine must leave the cab or the control panel of the host machine in order to insert and remove the safety locking pin. This can be both annoying and time-consuming for the machine operator, particularly if they must repeatedly change the implement which is attached to the adaptor. For this reason, some operators will not insert the safety locking pin into the adaptor after attaching an implement to the adaptor. However, if the locking pin is not inserted, the operator may forget to operate the moveable latch arms of the adaptor so that the implement is not secured to the adaptor, or the latch arms may inadvertently release the implement. In either case, the safety and welfare of the machine operator as well as the safety and welfare of other people and objects which are in the vicinity of the machine will be put at risk.

The aforementioned disadvantage of adaptors which have a manually inserted safety locking pin is addressed by an adaptor which is disclosed by Australian Patent No. 723305 and which includes a fixed set of latch arms, a moveable: set of latch arms which are remotely controlled, and a remotely controlled locking pin mechanism. The locking pin mechanism includes a ram pin which forms part of a hydraulic cylinder which is located substantially within the adaptor. The ram pin is extendible behind the moveable latch arms to mechanically lock the latch arms in their extended position, and thereby lock an implement to the adaptor. When the ram pin is extended to mechanically lock the latch arms in their extended position, a marker pin is pushed out by the ram pin so that the marker pin provides a visual indication that the latch arms are mechanically locked.

A problem with the adaptor disclosed by the '305 patent is that the marker pin may not be visible from the cab or the control panel of the host machine.

Moreover, the marker pin may malfunction so that it remains pushed out even when the ram pin is not extended, thus falsely indicating that the latch arms are mechanically locked by the locking mechanism. Therefore, to ensure that the moveable latch arms are mechanically locked, the operator of the machine mu:;t leave the cab or the control panel of the host machine in order to reliably determine whether the marker pin has been pushed out by the ram pin and therefore, whether or not the moveable latch arms are mechanically locked. Consequently, the aforementioned advantage of the adaptor disclosed by the '305 patent over adaptors which have a manually inserted safety locking pin is negated to a certain extent if the machine operator must leave the cab or the control panel of the host machine in order to determine the position of the marker pin and whether or not the latch arms of the adaptor are mechanically locked.

It would therefore be desirable to provide an adaptor which overcomes, or at least ameliorates, the aforementioned deficiency of the adaptor which is disclosed by the '305 patent.

Disclosure of Invention It is an object of the present invention to overcome, or at least ameliorate, one or more of the deficiencies of the prior art mentioned above, or to provide the consumer with a useful or commercial choice.

Other objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, a preferred embodiment of the present invention is disclosed.

According to a broad aspect of the present invention there is provided an adaptor of the type which is used to connect implements interchangeably to the end of an operating boom or arm and which comprises: a latch arm assembly moveable between a releasing position at which an implement is releasable from the adaptor, and a holding position at which the implement is held onto the adaptor; a locking mechanism having a remote controlled locking member, wherein the locking member is moveable between an unlocking position at which the latch arm assembly is moveable between the holding position and the releasing position, and a locking position at which the locking member mechanically locks the latch arm assembly in the holding position; a position determining means operable to determine the position of the locking member; and a position indicating means operable to indicate the position of the locking member, wherein the position indicating means is responsive to the position determining means.

The remote controlled locking member together with the position determining means and the position indicating means enable an operator of a host machine to which the adaptor is secured to control the locking member and to ascertain if it is in the correct position without the operator having to leave the cab or the control panel of the machine. This enables the operator to operate the locking mechanism and to ensure that the locking member is in the correct position with little if any adverse impact upon productivity.

In a preferred form, the latch arm assembly includes a latch arm and a hydraulic cylinder which is operable to move the latch arm between the releasing position and the holding position. Preferably, the latch arm is able to be moved to the holding position and the releasing position by respectively extending and retracting a piston of the hydraulic cylinder. In a particular preferred form, the latch arm is pivotable between the releasing position and the holding position.

Preferably, the locking mechanism may include a hydraulic cylinder which is operable to move the locking member between the unlocking position and the locking position. The locking member is preferably pivotable between the unlocking position and the locking position.

The position determining means preferably includes a plurality of hydraulic pressure sensors for sensing the hydraulic pressure inside the hydraulic cylinder of the locking mechanism at a plurality of locations along the length of the hydraulic cylinder, and a controller for determining the position of the locking member from the output of the pressure sensors. In a particular preferred form, the pressure sensors sense the hydraulic pressure inside the hydraulic cylinder at locations which are adjacent to the ends of the cylinder, and at a location which is located between the ends of the cylinder.

It is preferred that the controller is operable to prevent the latch arm assembly from being moved from the holding position while the locking member is displaced from the unlocking position. In a particular preferred form, the controller is operable to prevent a hydraulic control valve of the adaptor from being operated and causing the latch arm assembly to move from the holding position while the locking member is displaced from the unlocking position.

The controller of the position determining means may be operable to prevent the locking member from being moved from the unlocking position while the latch arm assembly is displaced from the holding position. In a particular preferred form, the controller is operable to prevent a hydraulic control valve from being operated and causing the locking member to move from the unlocking position while the latch arm assembly is displaced from the holding position.

The position indicating means preferably includes a visual indicator or an audible indicator. For example, the position indicating means may include at least one light-emitting diode (LED) or an audio speaker for emitting an audible alarm. In a particular preferred form, the position indicating means includes a red LED, a green LED, and a speaker.

Brief Description of Drawings In order that the invention may be more fully understood and put into s practice, a preferred embodiment thereof will now be described with reference to the accompanying drawings, in which: Figure 1 is a side elevation of an adaptor according to the preferred embodiment of the present invention when the latch assembly of the adaptor is in the releasing position; Figure 2 is a perspective view of a lower portion of the adaptor depicted in figure 1; Figure 3 is a perspective view of the lower portion of the adaptor when the latch assembly is in the holding position; Figure 4 is a side elevation of the lower portion of the adaptor which depicts the latch assembly in the holding position, and the ports for connecting the pressure sensors of the adaptor's position determining means to the hydraulic cylinder of the adaptor's locking mechanism; and Figure 5 is a schematic electrical and hydraulic circuit diagram of the adaptor.

Best Mode for Carrying Out the Invention Referring to figure 1, an adaptor 10 is adapted to be mounted to the end of an arm or boom (not depicted), typically an excavator arm or the lifting arms; of an excavator earthmoving machine. The adaptor 10 is pivotally connected to the arm by pins inserted through pinholes 11. The adaptor 10 and the arm can be pivoted by the operator from the cab or control panel of the host machine.

As can be seen more clearly in figure 2, the adaptor 10 has a latch arm 12 and a set of caliper-like latch arms 13 for releasable attachment to an earth working implement or other tool attachment. The latch arms 13 are fixed relative to the adaptor 10, while the latch arm 12 is pivotable between a retracted releasing position which is depicted in figures 1 and 2, and an extended holding position away fi:om the fixed arms 13 as depicted in figures 3 and 4. Typically, the fixed latch arms 13 are integrally formed portions of two side plates 14A, 14B of the adaptor 10. The moveable latch arm 12 is pivotable about a pin 15 which extends between the side plates 14A, 14B.

The latch arm 12 is extended and retracted by a hydraulic cylinder 16 which is able to be remotely controlled by the operator in the control cab of the host machine.

The implement or other attachment (not shown) normally has two spaced bars. With the latch arm 12 retracted, the adaptor 10 is maneuvered to insert the latch arms 12, 13 between the two bars, and to hook the fixed arms 13 onto one of the bars.

The hydraulic cylinder 16 is then extended so that the latch arm 12 engages the other bar. In this manner, the implement is firmly grasped by the adaptor The adaptor 10 also includes a certified lifting point which is in the form of an eyelet 30 which extends from a plate 31 and a plate 32 which both extend between the side plates 14A and 14B. The eyelet 30 can be used for securing the adaptor 10 to loads which are suspended therefrom.

To ensure that the latch arms 12, 13 do not inadvertently disengage from the implement, e.g. in the event of hydraulic failure, a locking mechanism 17 is used to mechanically lock the moveable latch arm 12 in its extended position.

The locking mechanism 17 comprises a hydraulic cylinder 18 which is located in the space between side plates 14A and 14B. A pin 19 pivotally connects the cylinder 16 and cylinder 18 to lugs 20 which extend from a plate 21 which in turn extends between the side plates 14A, 14B. A pin 22 pivotally connects a locking member 23 to an end of a piston rod 24 of the hydraulic cylinder 18. The locking member 23 is also pivotally connected to the side plate 14A by a pin 25. The locking member 23 is able to be pivoted about the pin 25 by extending and retracting the piston rod 24 of the cylinder 18 which is able to be remotely controlled by the operator in the control cab of the host machine.

When the piston rod 24 is fully extended, the locking member 23 is in an unlocking position, and the latch arm 12 is able to be fully extended and fully retracted without the locking member 23 obstructing its movement. Figures 1 and 2 depict the locking member 23 when it is in the unlocking position.

When the piston rod 24 is fully retracted, the locking member 23 is in a locking position as depicted in figures 3 and 4. The piston rod 24 can only be retracted if the latch arm 12 is in the holding position because a protrusion 26 which extends from a side of the latch arm 12 would otherwise prevent the locking member 23 from pivoting from the unlocking position to the locking position. When the locking member 23 is in the locking position, the locking member 23 engages with the protrusion 26 and thereby prevents retraction of the latch arm 12 from the holding position to the releasing position.

A mechanical position indicator 27 is pivotally connected to the pin 22 and extends into an opening 28 in a plate 29 which itself extends between the side plates 14A and 14B. When the locking member 23 is in the locking position, the position indicator 27 protrudes from the opening 28 so that it is visible on the exterior of the adaptor 10 as depicted in figure 4. When the locking member 23 is in the unlocking position, the position indicator 27 is retracted so that it does not protrude from the opening 28 and is not visible on the exterior of the adaptor 10. The position indicator 27 therefore provides a means of visually determining the position of the locking member 23.

Although the position indicator 27 may be viewed by the operator of the host machine from the cab thereof, if the arm or boom of the machine or some other object obstructs the position indicator 27 from being viewed from the cab of the host machine, the operator usually must dismount the machine in order to determine the position of the indicator 27 and hence the locking member 23. As a consequence, the advantage of being able to remotely operate the locking member 23 is at least partially negated.

As shown in figure 4, the hydraulic cylinder 18 includes hydraulic ports 33A, 33B, and 33C. Port 33A is located adjacent the piston rod end of the cylinder 18, port 33C is located adjacent the cylinder end of the cylinder 18, and port 33B is located midway between the ports 33A and 33C.

Referring to figure 5, each port 33A, 33B, 33C is connected to an input of a respective hydraulic sensor 33AA, 33BB, 33CC. Sensors 33AA, 33BB and 33CC are I adapted to sense the hydraulic pressure inside the cylinder 18 at various locations 2 therein. Sensor 33AA is connected to port 33A and therefore senses the pressure at the piston rod end of the cylinder 18, sensor 33BB is connected to port 33B and therefore senses the pressure midway along the cylinder 18, and sensor 33CC is connected to port 33C and therefore senses the pressure at the base end of the cylinder 18.

O The outputs of the pressure sensors 33AA, 33BB and 33CC are fed to an Selectronic controller 34 which is able to determine the position of the piston rod 24 and therefore the position of the locking member 23 from the pressure sensor outputs.

The controller 34 in combination with the pressure sensors 33AA, 33BB and 33CC constitute a position determining means 35 of the adaptor The hydraulic cylinders 16 and 18 are controlled by a control valve module 36 which includes a first hydraulic control valve 37 for controlling the cylinder 16, and a second hydraulic control valve 38 for controlling the cylinder 18. Both of the control valves 37, 38 are solenoid-operated hydraulic control valves and are cormnected to a high pressure hydraulic line 39 and a low pressure hydraulic line The piston rod ends and the base ends of the cylinders 16, 18 are each connected to a respective line 39, 40. The particular line to which the piston rod ends and the base ends of the cylinders 16, 18 are connected depends on the position of the control valves 37, 38, and this dictates whether the pistons of the cylinders 16, 18 are extended or retracted.

A hydraulic check valve 41 which is connected to the base end of the cylinder 16 and the control valve 37 prevents the piston of the cylinder 16 from being retracted in the event of a hydraulic failure. A pilot line 42 also connects the check valve 41 to the piston rod end of the cylinder 16. Hydraulic fluid can only flow through the check valve 41 from the base end of the cylinder 16 if the hydraulic pressure in the pilot line 42 exceeds the hydraulic pressure in the base end of the cylinder 16.

The solenoid of the control valve 37 and hence the position of the control valve 37 is controlled by a switch 43 which is connected to a coil 44 of the solenoid.

Similarly, the solenoid of the control valve 38 and hence the position of the control valve 38 is controlled by a switch 45 which is connected to a coil 46 of the solenoid.

Both of the switches 43, 45 are located in the cab of the host machine. Switches 43 and 45 are each connected to a respective output of the controller 34.

A position indicating means 47 is responsive to the controller 34 and includes a red light-emitting diode (LED) 48, a green LED 49, and an audio speaker which are located inside the cab of the host machine.

When the piston rod 24 is fully extended so that the locking member 23 is in the unlocking position, the pressure sensors 33BB and 33CC sense a higher pressure inside the cylinder 18 than the pressure sensor 33AA. This pressure information is fed to the controller 34 which then determines that the locking member is in the unlocking position. The controller 34 causes the red LED 48 to illuminate and the speaker 50 to emit a continuous audible alarm so that the operator of the host machine is made aware that the locking member 23 is in the unlocking position without the operator having to leave the cab of the machine to visually check the position of the locking member 23.

When the piston rod end of the cylinder 18 is connected to the high pressure line 39 by the control valve 38, and the piston rod 24 is partially retracted, the sensor 33AA senses a higher pressure than the sensors 33BB and 33CC. The controller 34 determines that the piston rod 24 has been partially retracted and causes the red LED 48 to illuminate and the speaker 50 to emit an intermittent audible alarm so that the machine operator is made aware that the locking member 23 is partway between the unlocking and locking positions.

When the piston rod 24 is fully retracted so that the locking member 23 is in the locking position, the pressure sensors 33AA and 33BB sense a higher pressure than the pressure sensor 33CC, and the controller 34 determines that the locking member 23 is in the locking position and causes the green LED 49 to illuminate while the red LED 48 and the audible alarm are turned off. The illumination of the green LED 49 signifies to the machine operator that the locking member 23 is in the locking position and that it is safe to operate the machine.

If the piston rod 24 is partially or fully retracted when the latch arm 12 is in the holding position, the controller 34 controls the output thereof which is connected to the switch 43 so as to prevent the control valve 37 and hence the hydraulic cylinder 16 from being operated by the switch 43. This prevents the latch arm 12 from moving and causing damage to the locking member 23 or another part of the adaptor 10. The controller 34 allows the control valve 37 to be operated normally using the switch 43 when the piston rod 24 is fully extended so that the piston rod of the cylinder 16 is able to be extended and retracted.

If the piston rod of the hydraulic cylinder 16 is partially or fully retracted when the locking member 23 is in the unlocking position, the controller 34 controls the output thereof which is connected to the switch 45 so as to prevent the control valve 38 and hence the hydraulic cylinder 18 firom being operated by the switch This prevents the locking member 23 from moving and causing damage to the latch arm 12 or other part of the adaptor 10. The controller 34 allows the control valve 38 to be operated normally using the switch 45 when the piston rod of the hydraulic cylinder 16 is fully extended so that the piston rod 24 of the cylinder 18 is able to be extended and retracted.

Throughout the specification and the claims, unless the context requires otherwise, the term "comprise", or variations such as "comprises" or "comprising", will be understood to apply the inclusion of the stated integer or group of integers but not the exclusion of any other integer or group of integers.

Throughout the specification and claims, unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

It will be appreciated by those skilled in the art that variations and modifications to the invention described herein will be apparent without departing from the spirit and scope thereof. The variations and modifications as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

It will be clearly understood that, if a prior art publication is refelTrred to herein, that reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Claims (4)

1. An adaptor of the type which is used to connect implements interchangeably to the end of an operating boom or arm and which comprises: a latch arm assembly moveable between a releasing position at which an implement is releasable from the adaptor, and a holding position at which the implement is held onto the adaptor; a locking mechanism having a remote controlled locking member, wherein the locking member is moveable between an unlocking position at which the latch arm assembly is moveable between the holding position and the releasing position, and a locking position at which the locking member mechanically locks the latch arm assembly in the holding position; a position determining means operable to determine the position of the locking member; and a position indicating means operable to indicate the position of the locking member, wherein the position indicating means is responsive to the position determining means.

2. The adaptor of claim 1, wherein the locking mechanism includes a hydraulic cylinder which is operable to move the locking member between the unlocking position and the locking position.

3. The adaptor of claim 2, wherein the position determining means includes a plurality of hydraulic pressure sensors for sensing the hydraulic pressure inside the hydraulic cylinder at a plurality of locations along the length of the cylinder, and a controller for determining the position of the locking member from the output of the hydraulic pressure sensors.

4. The adaptor of any one of the preceding claims, wherein the position indicating means includes a visual indicator or an audible indicator. An adaptor of the type which is used to connect implements interchangeably to the end of an operating boom or arm, the adaptor being substantially as herein described with reference to the drawings.