EP1844199A1

EP1844199A1 - Quick coupling device for a work tool

Info

Publication number: EP1844199A1
Application number: EP06701671A
Authority: EP
Inventors: Olaf Skarvang
Original assignee: Gjerstad Mek Industri As
Current assignee: Gjerstad Mek Industri As
Priority date: 2005-02-04
Filing date: 2006-01-30
Publication date: 2007-10-17
Also published as: WO2006083172A1; NO20050638D0

Abstract

A quick coupling device (1) for connection to a work tool (2) which has quick coupling fastenings in the form of two parallel shafts (3, 4) that extend between supporting frames (5, 6) on the work tool, wherein the device has at a first end (I1) a first set of hooks or cups (7, 8) with their opening facing downwards and adapted to abut with a part of the circumference of a first (3) of the shafts, and has at its second, opposite end (1') a second set of hooks or cups (9, 10) with their opening facing towards the second end and adapted for abutment with a part of the circumference of a second (4) of the o shafts, and a first wedge (11) that is insertable under the first shaft (3) for locking the work tool (2) to the quick coupling device (1). The quick coupling device also has a second wedge (12) that is intended for insertion under the second shaft (4). The first (11) and the second (12) of the wedges are adapted to press the hooks or the cups (7, 8; 9, 10) against the respective one (3; 4) of the shafts with a clamping force essentially 5 along the same axis as the load forces on the hooks or the cups (7, 8; 9, 10) that are caused by the work tool when in use. The two wedges (11, 12) are slidable along respective sliding guides (H', 12') and are movable back and forth by means of one common actuator (13). The device is well suited for work tools which are reversible with regard to use.

Description

Quick coupling device for a work tool

The invention relates to a quick coupling device for connection to a work tool as disclosed in the preamble of the attached claim 1, preferably for use with excavators.

A wide variety of quick coupling means for excavators have existed for many years. The need for them has arisen primarily for two reasons:

• Because many different work tools for machines such as excavators have been developed, and there is a desire for frequent, fast and efficient work tool changes between the different tools.

• There may also be a need for a frequent change between, for example, two identical work tools, so that one can be maintained whilst the other is in use.

Without a quick coupling it is a relatively time-consuming operation to change work tools, and often two people are required to do the job. As a rule there are two connecting bolts that must be removed and then remounted. During the mounting, the holes in the work tool and the excavator arm must be fully aligned to allow the bolts to be mounted, and this means that a person is needed to direct the machine operator who is driving the machine.

When a quick coupling device is used, the whole operation can be done by the operator or driver alone. The quick coupling device is usually mounted on the working arm of the machine. The work tool must have mounted thereon fastenings which mate with the gripping device on the quick coupling device. The quick coupling device is brought into engagement with the work tool by manoeuvring the excavator. The work tool is then lifted up and put in a position which allows gravity to press it against the quick coupling device. The locking of the quick coupling device to the work tool is effected by a hydraulically generated driving force against the wedge or the like, or another mechanically generated driving force. If the locking driving force is hydraulic, it can be actuated from the cab of the machine. If it is a mechanical arrangement, it must be actuated by a key, handle or the like and the driver must stand close to the quick coupling. Ih both cases, the whole operation can be done by the driver alone, and relatively quickly.

The traditional quick couplings have been constructed in such manner that the work tool must be coupled in a fixed position in relation to the quick coupling and thus to the excavator. Recent years have seen the arrival on the market of quick coupling devices which make it possible to connect the work tool both in the conventional direction and turned 180° relative thereto. This means, for example, that a bucket can have its working edge pointing backwards towards the excavator as usual, or pointing forwards. For some operations this is extremely practical, and therefore these quick coupling devices have obtained a good footing on the market and are often termed "reversible".

One example of a known "reversible" coupling of this kind is shown in Fig. 1. As can be seen from the drawing, the fastenings on the work tool 2, for example, an excavator bucket, are formed of a first and a second parallel shaft, 3 and 4 respectively, which are fastened to two supporting frames 5, 6 on the bucket. At a first end 1', the quick coupling device has two semicircular hooks or cups 7, 8 whose opening faces downwards, and which abut with a part of the circumference of the first shaft 3. At a second end 1", the quick coupling device also has two semi-circular hooks or cups 9, 10 which are oriented with their opening facing towards said second end 1" and shaped so that they abut with a part of the circumference of the second shaft 4 on the work tool 2. The work tool 2 is then locked to the quick coupling device by means of a mechanically or hydraulically operated wedge 11 which passes under the shaft 3.

Since the coupling faces between the quick coupling and the work tool are subjected to substantial forces they will gradually become worn. In the hooks 7, 8 the wear on them, caused by, for example, jars and jolts, will be compensated by the wedge 11 moving further in under the shaft 3, and thereby maintaining a fixed clamping grip. There is no wedging action in connection with the hooks 9, 10, and therefore play will develop between the hooks 9, 10 and the shaft 4, and thus movement between them caused by jars and jolts on the work tool 2. This movement will result in further wear and material shortening, and will thus have an accelerating effect as the play between the hooks 9, 10 and the shaft 4 gradually becomes greater.

It is therefore usual to mount adjustable bearing plates 18 and 19 on the work tool. These plates rest against a face 20 under the quick coupling device and prevent movement between the face and the device. The face 20 rests against the plate 18 or 19 depending on which way the work tool is mounted on the quick coupling device. When wear occurs, this contact face can be adjusted by placing inserts, so-called shims 21, 22, under it. This will take up the play caused by wear, and thus counter movement and further wear. The drawback of this adjustment possibility is that it calls for constant checking to see if there is any play and thus a need for adjustment, and that such inserts and necessary tools must available to make the adjustment. It has been found that it is often difficult to have sufficiently good routines in this connection, and the result is often in any case unnecessary slack and wear.

As other examples of known quick coupling devices, reference can be made to US Patent 6058633 and US Patent Application 2003/0175072 Al, of which the first document describes a mechanically or hydraulically operated spring mechanism that presses cups or hooks in the quick coupling device around the fastening shafts on the bucket. There are no mechanical means that compensate for wear and slack in other directions. The quick coupling is also not a separate unit, but an integral part of a stick and link system on the excavator. The second document describes a hydraulic quick coupling which is made as a separate unit and actively grips the shafts on the bucket at both ends. This is done by means of clamps which are articulated and moved by an actuator. The device disclosed in this document is a quick coupling device which, inter alia, is intended to guard against the loss of equipment, and this is supported by the use of an extra safety bolt in front of the coupling. Means to remedy problems of slack and wear are not described. Moreover, both clamps act basically in the "horizontal plane", whilst the main direction of force is "vertical".

US Patent 6691438 teaches a solution which corresponds to that shown in the attached Fig. 1. The hooks or cups that cooperate with a wedge form almost point contact with the respective shaft on the work tool because the radius of curvature of the hooks/cups is substantially greater than that of the shaft. This causes substantial load forces on the wedge. There is no wedging action on the second shaft, which results in gradually increasing slack at this point of support for the work tool.

French Patent 2765601 relates to a quick coupling device with locking wedges at one end.

The invention is directed towards remedying the deficiencies of the known quick couplings, and this is accomplished by means a quick coupling device of the type mentioned in the introduction, which is characterised by the features disclosed in the characterising clause of claim 1

Advantageous embodiments of the invention are disclosed in the dependent claims.

The invention will now be described with reference to the attached drawings. Fig. 1 shows a per se known quick coupling device.

Fig. 2 is a schematic illustration, in partial section, of an embodiment of the quick coupling device according to the invention in cooperation with a work tool.

Fig. 3 is a perspective view of the quick coupling device from below.

Fig. 4 is a longitudinal section through the quick coupling device.

Fig. 5 is a perspective view of the section in Fig. 4 seen from below.

Fig. 6 is a perspective view of the quick coupling device and a work tool prior to connection, and Figs. 7 and 8 show respectively partial and full connection.

As described above and shown in Fig. 1, the traditional reversible quick coupling devices have had cup-shaped hooks 7, 8 at a first end which grip partly around one of the shafts 3 of the work tool, whilst at the second end it has also been usual to have hooks 9, 10. In addition, there is a wedge 11 which presses the shaft 3 into the hooks 7, 8.

The quick coupling device 1, according to the invention, is designed for connection to a work tool 2 which has quick coupling fastenings in the form of the two parallel shafts 3, 4 that extend between supporting frames 5, 6 on the work tool. The device has at its first end a first set of said hooks or cups 7, 8 with their opening facing downwards and adapted to abut with a part of the circumference of the first 3 of the shafts, and has at its second, opposite end the second set of hooks or cups 9, 10 with their opening facing towards the second end and adapted for abutment with a part of the circumference of a second 4 of the shafts. As shown also in Fig. 1, the first wedge 11 is insertable under the first shaft 3 for locking the work tool 2 to the quick coupling device 1.

Compared to the prior art solution, the quick coupling device also has a second wedge 12 which is intended for insertion under the second shaft 4. Thus, the first 11 and the second 12 of the wedges are designed to press the hooks or cups 7, 8; 9, 10 against the respective one 3; 4 of the shafts with a clamping force essentially along the same axis as the load forces on the hooks or cups 7, 8; 9, 10 which are caused by the work tool when in use. Therefore, the need for the adjustment of slack by using inserts, so-called shims, is obviated, which slack adjustment would otherwise be necessary because of movements, jars, jolts and wear, as mentioned in the above.

The two wedges 11, 12 are slidable along respective sliding guides 11', 12' and are movable back and forth by a single actuator 13, and the actuator has respective ends 14, 15 thereof connected to a bracket 16, 17 on a respective one of the wedges 11, 12. A stop 23 is provided in connection with the sliding guides 11', 12' to define the retracted positions of the respective wedges 11, 12 and to ensure that the wedges are drawn back into a suitable starting position.

As shown in the example in Figs. 6-8, the connection takes place in that the quick coupling device 1 is first positioned with its second end and the hooks/cups 9, 10 on a shaft, for example, the shaft 4 on the work tool, after which it is positioned with its first end and the hooks/cups 7, 8 on the other shaft, for example the shaft 3.

The actuator 13 is designed to drive the wedges 11, 12 away from or towards each other in order to produce an essentially equal clamping force from the two wedges 11, 12. Although it is possible to envisage an actuator that is mechanical or electromechanical, the actuator according to a preferred embodiment is a hydraulic jack. The actuator is so positioned on the quick coupling device 1 that once the connection with the work tool has been completed, it lies between the supporting frames 5, 6 on the work tool 2.

When the quick coupling device 1 and the work tool 2 are brought together as described above, and the actuator, for example, the hydraulic jack, is actuated, both wedges 11, 12 will be moved out and press the hooks or cups 7, 8, 9, 10 together with respective shafts 3 and 4 at both ends of the device. If any wear occurs, the wedges 11, 12 with their respective inclined plane 11", 12" will be pressed further out and prevent movement. The actuator 13 will at all times be actuated and provide a force which presses the wedges apart. On the drawings, the possible movement of the wedges 11, 12 is indicated by double arrows. As the actuator 13 is only connected to the two wedges 11, 12 and is otherwise freely moveable, it will be ensured that there is an equal force on both wedges 11, 12 at any given time.

When the work tool is to be uncoupled, the actuator 13 is made to draw together and thus draw the wedges out of engagement with the shafts 3 and 4. The quick coupling according to the invention can be made in different sizes and adapted to varying dimensions such as shaft diameter, distance between shafts and width between supporting ribs on the work tool.

Although in the above a quick coupling is described that is especially intended for use in connection with excavators, it is obvious that the principle according to the invention can also be applied in the case of other quick couplings where work tools are to be connected to machines or equipment. Although the quick coupling device will normally be suitable for use with most work tools that are to be operated by a machine, it is also - as mentioned - highly suitable for use with work tools that are to be reversible, for example, where in one operation mode masses are to be dug up in a backward direction, whilst in another operation mode the masses are to be dug up in a forward direction. The use of two wedges which prevent slack from easily developing in the load direction, results in a considerably longer useful life for the hooks or cups of the quick coupling device, and in addition a longer lifetime for the shafts of the work tool, i.e., before necessary repairs or changes must be made.

Claims

P a t e n t c l a i m s

1.

A quick coupling device (1) for connection to a work tool (2) which has quick coupling fastenings in the form of two parallel shafts (3, 4) that extend between supporting frames (5, 6) on the work tool, wherein the device has at a first end a first set of hooks or cups (7, 8) with their opening facing downwards and adapted to abut with a part of the circumference of a first (3) of the shafts, and has at its second, opposite end a second set of hooks or cups (9, 10) with their opening facing towards the second end and adapted for abutment with a part of the circumference of a second (4) of the shafts, and a first wedge (11) that is insertable under the first shaft (3) for locking the work tool to the quick coupling device, characterised in that the quick coupling device also has a second wedge (12) that is intended for insertion under the second shaft (4); - that the first (11) and the second (12) of the wedges are adapted to press the hooks or the cups (7, 8; 9, 10) against the respective one (3; 4) of the shafts with a clamping force essentially along the same axis as the load forces on the hooks or the cups (7, 8; 9, 10) that are caused by the work tool when in use; and that the two wedges (11, 12) are slidable along respective sliding guides (11¹, 12') and are movable back and forth by means of one common actuator (13).

2.

A quick coupling device according to claim 1, characterised in that the actuator has respective ends (14, 15) thereof connected to a bracket (16, 17) on a respective one of the wedges (11, 12).

3.

A quick coupling device according to claim 2, characterised in that the actuator (13) is adapted to drive the wedges (11, 12) away from or towards each other to produce an essentially equal clamping force from the two wedges (11, 12).

4.

A quick coupling device according to claim 1, 2 or 3, characterised in that the actuator

(13) is a hydraulic jack.

5.

A quick coupling device according to claim 1, 2, 3 or 4, characterised in that the actuator (13) is so oriented that it will be lie between the side members (3, 3') of the work tool when the quick coupling device (1) is fastened to the work tool (2).

6.

A quick coupling device according to any one of the preceding claims, characterised in that a stop (18) is provided in connection with the sliding guides (H', 12') to define the retracted positions of the respective wedges (11, 12).