GB2028078A - Improvements in and relating to boom assemblies - Google Patents

Abstract

The invention provides a boom assembly in which the boom 10 is suspended from a boom support (12, 14) by inclined links (16, 18) with a spacer (30) arranged to space the middle of the boom from the support (12, 14). The links (16, 18) transmit to the boom (10) the effects of any long term forces acting on the boom support (12, 14) and provide stabilising or restoring forces on the boom whenever the effect of any horizontal or vertical short term forces acting on the boom is such as to urge or hold the boom away from a predetermined desired disposition relative to the boom support. In some embodiments, the boom is suspended by links from an intermediate member which is itself suspended by links from the boom support. <IMAGE>

Description

SPECIFICATION Improvements in and relating to boom assemblies The invention relates to boom assemblies and in particular to boom assemblies for agricultural use.

Spraying machines for agricultural use consist of a tank, pump, spray boom fitted with nozzles, control valves and filters. Both towed machines and self-propelled machines are known.

If the spray is to be uniformly distributed, then ideally the spray nozzles should move at a constant speed and at a constant height over the ground or crop being treated. In practice it is difficult to achieve these ideal conditions. First, local irregularities in the supporting ground surface will cause the machine to roll and this will result in erratic vertical movement of the spray boom especially at its tips, causing varying overlap of the spray patterns from adjacent nozzles.Secondly, if the spray boom is resiliently mounted in an attempt to isolate the boom from the rolling motion discussed above and encourage it to remain horizontal independently of the sideways orientation of the machine, this very effect will be counter productive when the machine is operating on a side slope because in this latter situation it is clearly desirable if uniform spraying is to be achieved along the length of the boom that the boom should remain not horizontal but parallel to the side slope along which the machine is running.

Thirdly, when the machine yaws, this will impart a horizontal whipping movement to the spray boom which will be superimposed on the usual translational movement of the boom. The consequences of this whipping movement, which have not been generally appreciated, may be serious especially at the tips of the spray boom where at any given moment, one end of the boom is moving too slowly or may even be moving backwards whilst the other end of the boom is moving too fast.As the boom will tend to oscillate between this extreme position and the opposite one in which the "slow" end of the boom is now moving too fast and vice versa, it will be seen that this effect will tend to result in some regions of the area under treatment receiving well above the intended dose of spray (slow boom movement) and adjacent regions receiving well below the intended dose (fast boom movement).

Attempts have been made to isolate the boom from machine roll whilst also maintaining correct alignment for side-slope operation.

Typical of these are the solutions proposed by Demaret in British Patent Specification 1491787 and by Leoffler in US Patent Specification 3580505. Machines are also known in which the boom is pivotally attached to a body portion of the machine by links inclined so that their lines of action intersect near the centre of gravity of the boom. In this case, the boom remains parallel to the ground on side slopes and the links apply a restoring force returning the boom to this position when once it has been disturbed e.g. by machine roll.

The drawback with this last arrangement however, as with all the arrangements so far discussed, is that no means are provided for isolating the boom from machine yaw. It may be interesting to note in this respect that Demaret mentions the problem in his patent specification but proposes no solution to it.

The only spraying machine currently known to the Applicant in which some attempt has in fact been made to isolate the boom from machine yaw, is that proposed by de Meeus in British Patent Specification 1 464751 and 1464752. In the de Meeus machine, a support frame is connected to a body portion of the machine by a vertical pivot and by shock absorbers arranged to dampen rotation of the support frame about the pivot. The spray boom is mounted on a second frame connected by links and guides to the support frame. The links and guides maintain the two frames in substantially parallel planes but allow a relatively pivotal motion within these planes. Thus in essence the de Meeus machine relies on a pendulum suspension to isolate the spray boom from tilting of the machine and on a damped pivotal motion to isolate the boom from yaw.

However the de Meeus machine suffers from a serious disadvantage stemming from the fact that although de Meeus sets out to damp the boom against yaw, he makes no attempt to restore the boom once yaw displacement has taken place. Thus once the boom has been reorientated, it will remain at this new orientation until subsequent yawing moves it to a new orientation which may be nearer or further from that originally intended.

Apart from the uneven spray distribution that will occur while yawing is actually taking place (due to one half of the boom moving too fast over the ground and the other half too slowly), there is the further drawback that for any but the intended orientation of the boom perpendicularly across the line of motion of the machine, the area treated by the machine will be narrower than the intended spread and the side regions of this spread will not be treated at all.

It is an object of the present invention to provide a boom assembly for a spraying machine in which these disadvantages are significantly reduced or overcome.

According to the present invention, a boom assembly e.g. for use on a sprayer machine, comprises a boom suspended from a boom support on a plurality of inclined links with a spacer means arranged to space the middle of the boom from the support, the links being constructed so as to transmit to the boom the effects of any long term forces acting on the boom support e.g. as when the machine yaws or passes over a bump in the ground, and being arranged to provide stabilising or restoring forces on the boom whenever the effect of any horizontal or vertical short term forces acting on the boom is such as to urge or hold the boom away from a predetermined desired disposition relative to the boom support.

In a first embodiment, the links are rigid and operate to transmit the effects of "long term forces on the boom support e.g. forces arising from side-slope operation, and stability in the assembly is achieved by having the links so inclined that movement of the boom towards or into a disposition other than said desired disposition raises the centre of gravity of the assembly.

As an alternative to the rigid link embodiment described above, the links may in fact be resiliently extensible in which case they operate to transmit the effects of the long term forces referred to earlier whilst short term disturbances result in some of the links being extended so as to produce tensile restoring forces on the boom whenever the boom is urged towards or into a disposition other than said desired disposition.

Conveniently, the links between the boom and the boom support or, if an intermediate member is present, the links between the boom and the intermediate member, are downwardly convergent. Alternatively, these links may be upwardly convergent.

In the various systems outlined above, the spacer means preferably operates on the middle of the boom so as to minimise any effect it might otherwise have on the boom apart from its spacing action.

Thus in one embodiment, the spacer means comprises a swing-link assembly connected to the boom by a vertical axle member passing through the middle of the boom.

In another embodiment, the spacer means comprises a roller/guide assembly with the rotation axis of the roller part passing vertically through the middle of the boom.

For satisfactory performance any of the above arrangements may require the provision of some form of damping means in either or both planes of action.

The invention also includes a spraying assembly comprising a boom assembly according to the present invention in combination with a spray bar carried by the boom. The invention further includes a spraying machine comprising a tank, a pump, a spraying assembly according to the present invention, control valves and filters.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figures 1 and 2 show diagrammatic perspective views of alternative boom assemblies using rigid links according to the present invention.

Figures 3 and 4 show diagrammatic perspective views of an extensible-link version and of an alternative design of spacer means for use in any of the embodiments illustrated in the earlier Figures.

Figures 5, 6 and 7 show a front elevation, a plan view and a side view cross-sectioned (on line A-A of Fig. 5) of a more practical embodiment, and Figures 8, 9 and 10 show a front elevation, a plan view and a side view cross-sectioned (on line B-B of Fig. 8) of an alternative embodiment to that shown in Figs. 5 to 7.

Thus referring first to Fig. 1, a boom assembly according to the present invention comprises a boom 10 suspended from a boom support 12, 14 on two rigid links 16, 18.

The links 16, 1 8 carry at their ends the first parts of universal joints 20, 22, 24, 26 the second parts of which are attached to boom support 1 2 and to boom 10 respectively.

Reference numeral 28 indicates a swinglink spacer arranged to space the middle of the boom 10 from the support 12, 14. In more detail, the spacer 28 comprises parallel links 30, 32 arranged to move in a horizontal plane between two pivots 34, 36 the first mounted on the boom support 12, 14 and the latter providing a vertical axle member passing through the middle of the boom.

It will be observed that the two links 16, 1 8 are inclined and control the motion of the boom 6 relative to the supports 12, 14 in both the vertical and the horizontal planes.

Fig. 2 illustrates the alternative system in which the "multidirectional" links 16, 1 8 of the earlier embodiment are replaced by two sets of links 38, 40 and 42, 44 connected together by an intermediate member 46. The combined effect of links 38-44 is of course substantially the same as that of links 16, 1 8 in the first embodiment.

The other parts in Fig. 2 have been identified by the same reference numerals as were used to indicate the corresponding parts in Fig. 1.

It will be noted that in both the embodiments above described, the motion of the boom is closely controlled by bearing surfaces in the various link systems proposed. These surfaces can be accurately formed to give a precise control of the boom and contrast favourably with the guide system employed in the de Meeus design where the clearances between the guide surfaces and the parts they engage will unavoidably introduce a certain amount of "play" in the vertical plane which in turn will impose limitations on the accuracy with which the boom can be controlled.

Turning now to Fig. 3 of the accompanying drawings, it will be seen that the rigid links of the earlier two embodiments have been replaced by extensible links 48, 50, 52, 54 e.g.

in the form of spring-return hydraulic dampers. As already explained, in this embodiment the stabilising forces on the boom will be generated by a different mechanism to before but apart from this the design is largely similar and once again the same reference numerals have been used to indicate like items.

Turning now to Fig. 4, this shows a middle portion of the boom provided with a roller/ guide spacer system 56 which can be used instead of spacer 28 in the embodiments of Figs. 1 and 2. As may be seen from Fig. 4, spacer 56 comprises two rollers 58, 60 running between parallel guides 62, 64, 66, 68 supported on the boom-support (not shown).

The roller axle 70 passes through the middle of the boom from its support so as to minimise any effect on the boom that might otherwise occur apart from spacing.

In operation of the assemblies described above in accordance with the present invention, it is found that the links support the boom in such a way that vertical shocks imposed when the spraying machine rolls can be absorbed by the link system whereas longterm inclinations e.g. as with side slope opertion are faithfully transmitted to the boom which remains accurately parallel at all times to the area under treatment. Because of the multidirectional nature of the link system, horizontal shocks imposed by machine yaw, can also be accommodated.

Clearly the detailed design of the assembly can be varied to suit different situations. For example the downward convergence of the pairs of links in Figs. 1 and 2 can be replaced by upward convergence if desired or by having the links parallel to one another. In this respect, upward convergence is probably to be preferred if the ground is basically horizontal but there are significant irregularities to deal with whereas downward convergence is to be preferred if the machine is to be operated on a side slope.

Turning now to Fig. 5 to 7, the machine illustrated there comprises a main frame 100, a sub-frame 101, a boom assembly 102 supported on a sub-assembly 103, and a number of links (identified below) by which the sub-assembly is suspended from the frame and sub-frame.

The main frame carries two brackets 105, 106 which support the top ends of two rigid link suspension members 107, 108. The lower ends of these members are connected to the sub-assembly 103.

The boom assembly 102 (which carries the spray boom 110) is secured to the sub-assembly by bolts 112, 11 3 and as best seen from Fig. 5, the links 107, 108 converge downwardly so as to have their lines of action meeting at or near the centre of gravity of the link-supported system.

Beneath the brackets 105, 106, the main assembly 100 supports the sub-frame 101 and rigid-link spacers 115, 11 6 act between the sub-frame and the middle-section of subassembly 103.

The arrangement is completed by optional shock absorbers 118, 11 9 acting between the main frame 100 and the sub-frame 101 and by a pair of shock absorbers 120, 121 acting between subframe 101 and the middle section of a sub-assembly 103.

To complete an understanding of the three Figures, the following points should be borne in mind. First that reference numeral 1 22 has been used throughout to indicate knucklejoints and numeral 1 23 to indicate doublepivot universal joints, and secondly that the reference numerals for a general part e.g. the main frame; have been used more than once in the same Figure to indicate different portions of the part concerned.

Thirdly, that items shown in one Figure have in some cases been omitted from another Figure in the interests of clarity.

These general guide lines to the interpretation of Figs. 5 to 7 also apply to Figs. 8 to 10 in which items similar or identical to items shown in Figs. 5 to 7 or performing similar or identical functions have been identified in both groups of Figures by the same reference numerals.

As will readily be seen, Figs. 8 to 10 show an alternative embodiment in which an important difference is that the spacers, 115, 11 6 have been replaced by a roller system comprising vertical guide plates 125, 1 26 on the sub-assembly and co-operating rollers 128, 129 carried on brackets 131, 132 of the subframe 101.

As compared with the earlier described embodiment, the embodiment of Figs. 8 to 10 offers a more compact design because with the omission of links 115, 11 6 the sub-frame and sub-assembly can be mounted closer together. In addition, the roller/guide plate arrangement ensures that the spacing apart of these two items is independent of any side-toside swinging motion of the boom and boom assembly. With the link spacers 115, 11 6 of the earlier embodiment, this spacing will vary to some degree (but not to an unacceptable extent) as the orientation of these links varies.

Claims (20)

1. A boom assembly comprising a boom suspended from a boom support on a plurality of inclined links with a spacer means arranged to space the middle of the boom from the support, the links being constructed so as to transmit to the boom the effects of any long term forces acting on the boom support and being arranged to provide stabilising or restoring forces on the boom whenever the effect of any horizontal or vertical short term forces acting on the boom is such as to urge or hold the boom away from a predetermined desired disposition relative to the boom support.

2. A boom assembly as claimed in Claim 1 in which the boom is suspended by links from an intermediate member which is itself suspended by links from the boom support.

3. A boom assembly as claimed in Claim 2 in which the links between the boom and the intermediate member are movable substantially only in either the horizontal or the vertical plane and the links between the inter mediate member and the boom support are movable relative to the intermediate member substantially only in the other of these two planes.

4. A boom assembly as claimed in Claim 1 or Claim 2 in which each link is arranged with its line of action inclined so that it can apply stabilising or restoring forces in both the horizontal and the vertical planes.

5. A boom assembly as claimed in Claim 4 in which each link is connected by universal joints to the boom, to the boom support, and, where present, to the intermediate member.

6. A boom assembly as claimed in any preceding claim in which the links are rigid and so inclined that movement of the boom towards or into a disposition other than said desired disposition raises the centre of gravity of the assembly.

7. A boom assembly as claimed in any of Claims 1 to 5 in which the links are resiliently extensible so as to produce tensile stabilising forces on the boom whenever the boom is urged towards or into a disposition other than said desired disposition.

8. A boom assembly as claimed in any preceding claim in which the links between the boom and the boom support or, if an intermediate member is present, the links between the boom and the intermediate member, are downwardly convergent.

9. A boom assembly as claimed in any of Claims 1 to 7 in which the links between the boom and the boom support, or if an intermediate member is present, the links between the boom and the intermediate member, are upwardly convergent.

10. A boom assembly as claimed in any preceding claim in which the spacer means acts only at the middle region of the boom.

11. A boom assembly as claimed in Claim 10 in which the spacer means comprises a swing-link assembly connected to the boom by a vertical axle member passing through the middle of the boom.

1 2. A boom assembly as claimed in Claim 10 in which the spacer means comprises a roller/guide assembly with the rotation axis of the roller part passing vertically through the middle of the boom.

1 3. A boom assembly as claimed in any preceding claim including damping means in either or both planes of action.

14. A boom assembly substantially as hereinbefore described with reference to and as illustrated in Fig. 1 of the accompanying drawings.

1 5. A boom assembly substantially as hereinbefore described with reference to and as illustrated in Fig. 2 of the accompanying drawings.

16. A boom assembly substantially as hereinbefore described with reference to and as illustrated in Figs. 3 and 4 of the accompanying drawings.

1 7. A boom assembly substantially as hereinbefore described with reference to and as illustrated in Figs. 5 to 7 of the accompanying drawings.

1 8. A boom assembly substantially as hereinbefore described with reference to and as illustrated in Figs. 8 to 10 of the accompanying drawings.

19. A spraying assembly comprising a boom assembly as claimed in any one of Claims 1 to 1 8 in combination with a spray bar carried by the boom.

20. A spraying machine comprising a tank, a pump, a spraying assembly as claimed in Claim 19, control valves and filters.