AU664923B2 - Improved pallet dispenser - Google Patents

Description

/U/1 1 28WO Regulation 3,2(2)

AUSTRALIA

Patents Act 1990 6 6 2

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT 3 Application Number: Lodged: Invention Title: IMPROVED PALLET DISPENSER The following statement is a full description of this invention, including the best method of performing it known to us bls~~r I-I 1 IMPROVED PALLET DISPENSER TECHNICAL FIELD The prrsent application relates to pallet dispensers, in particular, pallet dispensers which include means for sensing the presence or absence of a pallet, and to the construction of such sensors.

BACKGROUND ART Pallet dispensers are used in warehouses and the like to dispense empty reusable pallets for use as required. One class of dispensers uses sensor means to determine whether a pallet is present or not, and if no pallet is in the dispensed position, to dispense a pallet. An example of this type of apparatus is disclosed in the co-pending commonly assigned US application No. 842328.

This disclosure uses whisker switches to sense a pallet. However, whisker switches are subjected to considerable force in a typical pallet dispenser environment, and are prone to damage, particularly when a pallet is moved so S. 15 as to reverse the direction of travel and so force the whisker directly into the pallet.

Conventionally, a light and photoelectric sensor arrangement is used, such that anything blocking a clear sight causes the dispenser to refrain from dispensing a further pallet. This type of arrangement is known from, for example, US Patent No. 4557656 to Ouellette, and Australian application No. 40895/78 to U.E.B. Industries Ltd. The blockage is intended to be a pallet, however in an industrial situation, tape, cardboard, or other rubbish may obscure clear sight and prevent a further pallet being dispensed.

US Patent Nos. 4047622 to Blessing, 3623618 to Shaw, and 4172686 to Shorthouse disclose mechanical arrangements which sense the height of pallets, or the associated mechanism, rather than the presence or absence of a pallet at the dispensed position or positions.

It is accordingly an object of the present invention to provide an improved pallet sensing arrangement.

SUMMARY OF INVENTION The present invention may comprise according to one aspect a sensor for determining the presence or absence of a pallet, comprising a body mounted so as to displace in the plane of a substantially horizontal pallet so as to allow said pallet to travel past said body, said body being biased such that when no pallet is present it assumes a first position, and when engaged by a pallet it assumes a second position, said body engaging a switch means so as to provide a signal indicating the presence or absence of a pallet, wherein said body hp a shaped engaging surface adapted to be slidably engaged by pallets from a plurality of directions, said body displacing in response to such engagement.

Preferably said engaging surface includes at least one side surface which presents an acute angle to a direction of engagement by pallets.

oooo Preferably said side surface or surfaces taper upwardly.

G Preferably there are at least two side surfaces.

S Preferably said engaging surface includes a front surface having at least a portion tapering upwardly.

S According to another aspect, the present invention comprises an automatic pallet dispenser having at least one dispensing position, wherein dispensed pallets are removed along one axis of the dispenser, and at least one sensor for determining the presence or absence of a pallet is disposed along a side of the dispenser, characterised in that said sensor comprises a body mounted so as to displace away from said axis, said body being biased such that when no pallet is present it assumes a first position, and when engaged by a pallet it assumes one or more second positions, said body engaging a switch means so as to provide a signal indicating the presence or absence of a pallet, wherein said body has a shaped engaging surface adapted to be slidably engaged by movement of pallets along at -2aleast the axis of the dispenser so as to displace said body and allow movement of pallets along said axis.

In another broad form, the inventor provides an automatic pallet dispenser/stacker having a dispensing station which dispenses or receives pallets; the station having an entry opening and an exit opening and pallets may enter or leave the station via the entry opening or exit opening, pallets passing through the entry opening travelling along a first axis and pallets passing through the exit opening travelling along a second axis; ea0 a sensor for determining the presence or absence of a pallet S- in the station; S the sensor including; a body extending in the station and movable between a first position, when a pallet is absent the station, and a second ~position, when a pallet is present in the station; O a0 S biassing means to bias the body to the first position; S" the body having an engagement surface for slidably engaging a pallet as it passes into and out of the station along the first or second axis and for causing the body to move between the first and second positions as the pallet slides past the body.

Preferably there are two dispensing positions, and at least two sensors.

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-2b- Preferably the dispenser has two dispensing positions arranged as a front and rear position in line so as to allow access for removal from a single direction, said sensors being mounted one adjacent the front of the rear dispensing position, and the other adjacent the front of the front dispensing position.

According to another aspect the present invention comprises a pallet p

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w w ow ool o *eO* ,I handling device including at least one sensor according to the present invention.

The present invention provides a simple, reliable sensor arrangement suitable for use in both single and multiple pallet applications. A particular advantage of the preferred embodiment is the ability to reliably sense pallets which engage the sensor from either side, as well as from the front.

BRIEF DESCRIPTION OF DRAWINGS An illustrative embodiment will now be described with reference to the drawings, in which: Figure 1 shows schematically a single pal!et dispenser; Figure 2 shows a view looking down on the sensing means; Figures 3, 4 and 5 shows respectively side elevation, front and rear views of the illustrative lever device; Figure 6 shows schematically the placement of the inventive sensing S. 15 means in a single pallet dispenser; and Figure 7 shows schematically the placement of the inventive sensing means in a double pallet dispenser.

DESCRIPTION OF EMBODIMENT Referring to Figure 1, a schematic illustration of a pallet dispenser is shown. A hopper 1 contains a number of pallets, typically 10 to 30. Clamp arm 6 and lift arms 3 allow for dispensing of pallets one by one as required. The lift arrangements per se do not form part of the present invention, and will be understood and well known to those skilled in the art. An illustrative systems is disclosed, for example, in co-pending US application No 842328.

The present invention is particularly concerned with the determination of whether a pallet 8 is waiting to be collected from the dispensed position 5, or whether another pallet needs to be dispensed as the pallet 8 has been taken.

The following discussion is directed principally at a single pallet machine, however, it will be apparent to the reader that the same principles, may be readily adapted to multi-pallet systems.

Referring to figure 1, an illustrative automatic pallet dispenser 9 comprises a hopper 1 containing a stack of pallets 8 for dispensing as required.

Lift arms 3 raise and lower the stack of pallets as required, and dispensing of pallets is effected by co-operation between clamp 6 and lift arms 3. The lift mechanism and control system may be housed in housings 2, 7.

Referring to figure 2, each sensor 10 comprises a housing 12, and a pivotally mounted lever body 20. The lever body 20 pivots about axis 11 shown in dotted outline. In an open, i.e. no pallet, position, switch 14 is open and the dispenser is arranged to cycle and dispense a new pallet. Switch 14 is mounted to step 13 and operated by lever body 20. Bias means 15, attached to the upper end of the lever body 20, ensure the lever remains forced outward unless a considerable force is placed on it. Bias means 15 may suitably be a coil spring, however, any other suitable arrangement may be used.

It will be appreciated that the exact mechanical arrangement may be varied while providing the functionality required by the present invention.

S 15 The shape of the lever must be carefully selected, so as to reliably engage while wearing well and being robust in use.

A preferred implementation of the lever body will be described with reference to figures 3 to 5. Referring to figure 3, the top portion 21 is adapted for connection to a suitable pivot arrangement, via opening 23. It will be understood that any conventional bearing arrangement, for example a pin or bolt, may be used to allow for pivoting. Rear end 22 is substantially flat, and front face 26,27 has two distinct angles. The lever body 20 in use will pivot in the direction of face 22, when operatively engaged by a pallet either on front face 26,27 or -either of sides 24 or S 25 The lever is preferably constructed from cast nylon 6 with an angle at edge 23 such that each face 24, 25 (figure 4) is 250 from the normal to the rear of the lever. It has been determined for nylon that the critical angle is about 130, but the extra margin is included for safety and reliability. It will be appreciated that for other materials, a different angle will be appropriate e.g. for a higher relative co-efficient of friction material such as steel, a larger angle is necessary.

The invention may be implemented with any suitable material, with appropriate modification to the angles of the faces. It is critical for satisfactory operation that

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the engagement between the lever body, and the pallet, be sliding in nature so that the body is displaced out of the line of pallet movement while the pallet is moved past.

Considering Figure 4, sloping faces 24, 25 are the main engaging surfaces. Portion 26 is cut away, and the front 27 surface is flat and at an angle to surface 26. Preferably, portion 26 is substantially vertical, and face 27 is at an angle of about 300 from vertical. From the rear, in Figure 5, the thickness of the walls 30 can be seen. This is illustratively 1 to 2 cm. Surfaces 35, 34 slope inwardly.

Switch 14 may be electric, but is preferably pneumatic in a pneumatic system, and hence allows the entire system to operate pneumatically. The invention is most advantageous when used in a double dispenser arrangement.

oeoo It is applicable to any type of dispenser, including hydraulic arrangements.

It is noted that one embodiment of the present invention uses only one 15 sloping face 24 or 25. The face which is angled on the front side of the lever body may be omitted, however, this is not preferred. Alternatively, multiple angled or curved faces could be provided.The present invention could be implemented using a smoothly curved surface to provide the necessary engaging surfaces. Similarly, the lever body may perform a linear rather than pivoting motion, or other mode of movement, if desired.

Referring to figure 6, this illustrates schematically the placement of the sensor 10 within a single bay pallet dispenser 36. For the purpose of illustration, only the pallets in the bottom row, or dispensing position, are shown. Pallet 8 is within housing 9, and access for removal of pallets is via direction 37. The S 25 sensor 10 is preferably placed at the one of the front positions 41, 42 of the housing. However, sensor 10 may alternatively be placed near the rear of the bay, at position 43. The latter is preferred in a pallet collating application.

Figure 7 is a similar schematic view to figure 6, showing a double pallet dispenser. Dispenser 40 comprises housing 39, and has two sensors 10A, The three angled sensor bodies allow for a pallet 8A to be sensed in the rear bay, as well as a pallet 8B in the front bay. The inventive arrangement allows for pallets to be dragged past the sensors 10A, 10B without damage, and to 6 pivot in response to such movements of pallets. It will be understood that the sensors may be placed on the other side, or more or less sensors used, within the general principle of the system.

It will be appreciated that while the disclosure is in terms of a pallet dispenser, the apparatus may be a collator as well, or alternatively a different pallet handling device such as a palletizer or depalletizer.

It will be appreciated that variations and additions are possible within the spirit and scope of the invention.

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Claims (13)

1. An automatic pallet dispenser/stacker having a dispensing station which dispenses or receives pallets; the station having an entry opening and an exit opening and pallets may enter or leave the station via the entry opening or exit opening, pallets passing through the entry opening travelling along a first axis and pallets passing through the exit opening travelling along a second axis; a sensor for determining the presence or absence of a pallet in the station; the sensor icluding: a body extending into the station and movable between a first position, when a pallet is absent the station, and a second position, when a pallet is present in the station; biasing means to bias the body to the first position; the body having an engagement surface for slidably engaging a pallet as it passes into and out of the station along the first e or second axes and for causing the body to move between the first and second positions as the pallet slides past the body.

2. The dispenser/stacker of claim 1 wherein the engagement surface includes a top surface which, when the body is in the first position, extends in a plane angled to the first axis, for slidably contacting a pallet moving along the first axis.

3. The dispenser/stacker of claim 1 or claim 2 wherein the engagement surface includes a first and second side surfaces which, when the body is in the first position, extend in planes angled to the second axis, for contacting a pallet moving along the second axis.

4. The dispenser/stacker of any one of claims 1 to 3 wherein the engagement surface includes a front surface which, when the body is in the first position, extends in a plane substantially parallel to the first and second axes.

The dispenser/stacker of any one of claims 1 to 4 wherein the body is pivoted about a third axis.

6. The dispenser/stacker of claim 5 wherein the third axis is parallel to the second axis.

7. The dispenser/stacker of claim 2 wherein the top surface extends in a plane parallel to the second axis.

8. The dispenser/stacker of claim 7 wherein the engagement surface includes first and second surfaces extending in planes angled to the second axis on either side of the top surface and which diverge in the direction of the first axis.

9. The dispenser/stacker of any one of claims 1 to 8 further including a pallet storage location, and means to move a pallet between the storage location and the dispensing station, via the S. entry opening.

The dispenser of claim 9 wherein pallets only move from the storage location to the dispensing station.

11. The dispenser of claim 9 wherein pallets only move from the dispensing station to the storage location.

12. An automatic pallet dispenser/stacker having: v- C -9- a dispensing station which dispenses or receives an individual pallet; said dispensing station having an entry opening and an exit opening and pallets may enter or leave the station via the entry opening or exit opening, pallets passing through the entry opening travelling along a first axis and pallets passing through the exit opening travelling along a second axis, perpendicular t-co the first axis; a sensor mounted in or on a side wall of thb dispensing station for determining the presence or absence of a pallet in the station, the sensor including: a body extending into the station and pivotably mounted about a third axis parallel to the second axis, the body pivotably movable about the third axis between a first position when a pallet is absent the station and a second position when a pallet is present in the station; biasing means to bias the body to the first position; the body having an engagement surface for slidably engaging the side of a pallet as it enters and leaves t he station via the entry or exit openings, the engagement surface comprising a top surface, first and second side surfaces and a front surface; and, when the body is in the first position, the top surface faces the entry opening and extends in a plane parallel to the second axis and is angled to the first axis; the side surfaces extend on either side of the top surface away from the entry opening in planes angled to both the first and second axes, the first side surface facing the exit opening; and the front surface extends between the top and side surfaces in a Dlane substantially parallel to the first and second axes.

13. A pallet dispenser/stacker, substantially as herein described with reference to the drawings. By its Patent Attorney MICHAEL M4ARTIN of CHRYSILIOU MOORE CHRYSILIOU May 1995 0* S S S S S S. S S. S S S S. S C4 1 P. ABSTRACT A sensing arrangement is disclosed for use in a pallet dispenser or the like, to determine whether a pallet is present or not. A body, having a shaped engaging surface, displaces in the plane of the pallets upon sliding engagement by a pallet, and suitably has side faces angled in both the horizontal and vertical planes,and a front face. S S e ogo e o* 1 «Ol•