GB2038153A - Improvements in agricultural sprayers or the like - Google Patents

Abstract

The invention relates to a device for protecting the spray boom of a vehicle-mounted agricultural sprayer against damage upon collision with an obstruction. In one embodiment, the sprayer has a boom support (3) carried by the vehicle, and a boom (4b) mounted via a hinge arrangement (5a, 5b, 5d) from the support for generally horizontal swinging movement relative to the latter, rearwardly from an operative position in which the boom projects laterally of the vehicle. A locking lever (7a) normally positively locks the hinge arrangement against displacement of the boom from its operative position. A tensioned trip wire (8) is mounted on the boom forwardly of the leading edge thereof, and at its inner end is connected to the lever (7a). When, during forward movement of the vehicle, the trip wire encounters and is deflected by an obstruction, the lever (7a) is rocked to unlock the hinge arrangement, allowing the boom to swing back freely to clear the obstruction. <IMAGE>

Description

SPECIFICATION Improvements in agricultural sprayers or the like The invention concerns devices for protecting booms, and is particularly though not especially concerned with spray booms of agricultural sprayers.

Spraying vehicles or other appliances used for the application of agricultural chemicals (for example fertilisers, herbicides, pesticides, insecticides or fungicides) utilise distribution outlets, such as spray nozzles, spaced along a relatively long and slender boom mounted transversely to the direction of travel of the appliance. The boom projects laterally of the vehicle or body of the appliance, and the outer ends of the boom may be a substantial distance from the operator. Due to operator error or misjudgement, it is not uncommon for the boom to strike obstructions (for example fence posts, trees, bushes or electric or telephone posts) during the course of field operation.

In orderto reduce the likelihood of boom damage by such collisions, prior agricultural sprayers have incorporated various types of protective devices, known as "breakback" devices, which, when the boom strikes an obstruction, allow the boom to swing back out of its normal operating position relative to the body of the sprayer, to clear the obstruction. Ideally such breakback devices should fulfill two basic functions. Firstly they should allow the boom to swing back freely, with negligible resistance, from its normal operating position, when it strikes an obstruction. Secondly, the devices should restrain the boom from unintentional or spurious yawing movement during normal unobstructed operation of the sprayer, i.e. in the absence of a collision.

Prior breakback devices have compromised and failed to fulfill these two apparently conflicting functions by using springsortheweightofthe boom in an attempt to restrain the boom in its normal operating position with a force of a magnitude which is sufficient to prevent spurious yawing movement of the boom, but which is small enough to permit the boom to swing back without undue resistance upon striking an obstruction. However, in practice, this compromise leads firstly to poor yaw resistance, and secondly to the boom being subjected to undesirably large bending loads since the boom has to overcome this restraining force before it can swing back to clear an obstruction.

It is an object of the present invention to provide an improved protective arrangement or breakback device which is capable of positively locking the boom in its operative position against yawing movement in the absence of an obstruction, but which is capable of releasing when an obstruction is encountered without the boom having to overcome any significant restraining force, to permit the boom to swing clear of the obstruction.

From one aspect, the present invention provides a mobile spray appliance or other boom-carrying appliance, having a boom support and a boom mounted from the support for swinging movement relative to the latter, means for normally positively locking the boom in an operative position against such relative swinging movement, and sensor means positioned to detect the presence of an obstruction in the path of the boom and operable, upon such detection, to cause the locking means to release to free the boom for said relative swinging movement.

The sensor means may be mounted on the boom, forward of at least the leading edge or face thereof in the normal direction of travel of the appliance, so as to detect an obstruction and release the locking means before the obstruction strikes the boom. The sensor means may be operable to effect detection along at least a major proportion of a length of the boom, and may also be effective to detect obstructions located beyond but adjacent the free end of the boom.

From another aspect, the invention provides a boom or other elongate member for attachment to a mobile appliance, such as an agricultural spray appliance, the elongate member having mounting means at or adjacent one end thereof for mounting the elongate member from the appliance so as to permit swinging movement of the elongate member relative to the appliance, means operable to positively releasably lock the elongate member in an operative position against such swinging movement, and sensor means carried by the elongate member, operable to detect the presence of an obstruction proximate the elongate member and, upon such detection, to release the locking means and thereby permit the said swinging movement of the elongate member.

From another aspect, the invention provides an arrangement for protecting a boom or other elongate member of a mobile appliance, such as a spray appliance, against damage due to collision of the elongate member with an obstruction during normal travel of the appliance, the arrangement comprising means for hingedly interconnecting the elongate member with a supporttherefor, releasable locking means operable to normally positively lock the hinge means against hinging movement, sensor means intended to be carried by the elongate member, and means for interconnecting the sensor means and locking means whereby, in operation, detection of an obstruction by the sensor means is operable to release the locking means and free the hinge means.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which; Figure 1 is a perspective view of a tractor fitted with an agricultural sprayer embodying the invention; Figure 2 is a fragmentary view, on an enlarged scale, of one embodiment of breakback device which may be utilised in the sprayer of Figure 1; Figure 3 is a fragmentary perspective view of the device of Figure 2; Figure 4 is a fragmentary perspective view of a second embodiment of breakback device; Figures 5 and 6 are views of the device of Figure 4, in association with different sensor arrangements; and Figure 7 is modified version of the breakback device of Figure 4, in association with a further form of sensor arrangement.

Figure 1 shows an agricultural tractor 1, on the rear of which is mounted a sprayer 2 intended to spray agricultural chemicals. The sprayer incorporates a fixed, central boom-support frame 3 carrying a spray boom system comprising a fixedly mounted centre section 4a and a pair of hingedly mounted lateral sections 4b. The boom sections are provided with liquid distribution outlets in the form of spray nozzles 4c.

As indicated diagrammatically in Figure 1, each lateral boom section 4b is mounted from the support frame 3 by hinge means 5 of a breakback device 6 which also includes releasable hinge-locking means 7, and sensor means 8 for actuating the locking means. The hinge means 5 permits the boom section 4b to swing back from its normal operative position shown when the sensor means 8 encounters an obstruction and releases the locking means 7 during forward travel of the tractor 1.

As shown in greater detail in Figures 2 and 3 the hinge means of each breakback device comprises inclined hinge plates 5a and Sb, the plate 5a being fixed, for example welded, to the support frame 3, and the plate Sb being attached by a horizontal pivot arrangement Sc to the boom section 4b. A pivot 5d, such as a nut and bolt, interconnects the plates 5a and 5b to permit the boom section 4b to swing about the inclined axis 5e.

The boom section 4b is also connected to the support frame 3 by a pivoted linkage indicated generally at 9 in Figure 2, which is adjustable by a nut 9a to permit the inclination of the boom section to be adjusted. The linkage 9 forms no part of the invention and will therefore not be described in detail, and has been omitted from the other Figures.

The locking means of each breakback device comprises an L-shaped latching lever 7a rockably mounted at 7b from the swingable hinge plate 5b.

The lower arm of the lever 7a which forms the base of the "L" is cooperablewith a slot7c (Figure 3) in or defined by a tapered latch plate 7d carried by the fixed hinge plate 5b. A light spring 7e normally biases the latter lever arm in an anticlockwise direction as viewed in Figures 2 and 3, i.e. into the slot 7c.

The lever arm is a close tolerance fit in the slot, and positively locks the hinge plates 5a and Sb against relative rotation about the pivot 5d with negligible play, thus positively locking the boom section 4b in its operative position, extending generally normally to the direction of travel of the tractor 7 as shown in Figure 1. Thus, with the locking means engaged unintentional or spurious fore or aft yawing movement of the boom section 4b about the pivot 5d is positively prevented.

The sensor means 8 of each breakback device comprises a trip wire, cord or cable, the outer end of which is anchored to or adjacent the outer end of each boom section 4b, and has an intermediate portion 8b extending along the leading edge of the boom section. The portion 8b of the trip wire is spaced forwardly of the boom section 4b, and supported therefrom, by means of spacers 8a (Figure 1) attached to the boom section. The inner end & of the trip wire slidably passes through a sleeve 8d carried by the boom section 4b as shown in Figure 2, and is attached to the generally upright arm of the latching lever 7a.

With this arrangement, it will be apparent that, during forward travel of the tractor 1, any obstruction in the path of either of the lateral boom sections 4b will firstly encounter the trip wire portion 8b, and will deflect the latter, thus rocking the latching lever 7a in a clockwise direction and disengaging it from the latch slot 7c. The boom section 4b will thus be free to swing back clear of the obstruction with a minimum of resistance immediately the obstruction encounters the boom section. The proportions of the latching lever 7a and/or the strength of the spring 7e will of course be arranged so that the latching lever will not be tripped by insubstantial obstructions, such as crops or weeds which would not impose significant bending loads on the boom section.

As the boom section swings back, due to the inclination of the axis 5e, it will lift slightly so that, when the outer end of the boom section has cleared the obstruction, the weight of the boom section will cause the latter to swing and return to its original operating position as shown. During the final part of this return movement, the latching lever will ride up the inclined face of the tapered latch plate 7d and then drop into the slot 7c against the biasing action of the spring 7e. The inclination of the axis 5e and therefore the rise and fall of the boom section, will be sufficient merely to produce this return motion of the boom section, without resisting breakback to a degree which would subject to the boom section to significant bending loads.

Figures 4 and 5 show a second embodiment of breakback device in which the latching lever of Figures 2 and 3 is replaced by a latching plunger 7f slidablycarried by the hinge plate 5a and normally biased by a spring 7g into engagement with an aperture 7h in an upright latch plate 7i carried by the hinge plate Sb. The plunger 7f is connected to the inner end & of the trip wire, and is retractable from the aperture 7h against the action of the spring 7g when the intermediate portion 8b of the trip wire is encountered by an obstruction.

The trip wire may be arranged as shown in Figure 1, in which the intermediate portion 8b slides relative to one or more of the spacers 8a, or is fixed relative to one or more of the latter which are mounted to rock about generally upright axes relative to the boom section 4b. Alternatively, as shown in Figure 5, the outer end of the trip wire may be anchored to a rigidly mounted spacer, and to a rockable inner spacer. The outer spacer is inclined to project laterally beyond the end of the boom section 4b so that thetrip wire will encounter, and the latching plunger 7fwill be released by, an obstruction beyond but proximate the outer end of the boom section.

Figure 6 shows an alternative sensor arrangement in which the trip wire includes a portion 8e extending along, and aft of, the trailing edge of the boom section 4b as well as the portion 8b extending along, and fore of, the leading edge of the boom. With this arrangement, the breakback device will release to protect the associated boom section when the tractor is travelling in reverse, as well as forwards.

The sensor arrangements shown in Figures 5 and 6 are equally applicable to the breakback device shown in Figures 2 and 3.

Figure 7 illustrates a general form of breakback device in which the latching plunger (or lever or other latching member or mechanism) is servooperated by electrical, electro-mechanical, electromagnetic, pneumatic or hydraulic means, or any combination thereof. In this event, the sensor means 8f may be, or include, a flexible or rigid trip member triggered, upon contact with an obstruction, to trip or actuate the latch via appropriate electrical or fluid circuitry. Alternatively, the sensor means 8f may comprise fluid, electrical or optical proximity sensors which are triggered when an obstruction interrupts, disturbs or modifies associated waves or fields, such as pressure, electrostatic or electromagnetic fields or electrical or optical beams.

From the foregoing, it will be seen that there are provided particularly advantageous forms of breakback devices or mechanisms which positively lock the associated booms against spurious yawing movement during normal and unimpeded operation of the booms. The devices are released to allow substantially free breakback of the booms when obstructions are detected by sensors associated with the booms, and before the obstructions strike the booms. The booms are therefore subjected to negligible bending loads as a result of such release and breakback, and do not have to be designed, or strengthened, to withstand bending forces of the prior breakback devices, or the effect of direct impact by obstructions prior to release of the breakback devices.Thus, breakback devices embodying the invention may be utilised with spray booms of a significantly lighter, and therefore possibly more fragile, form than has previously been practicable, for example spray booms of glass-fibre reinforced plastics, without risk of damage.

It will be understood that various modifications may be made without departing from the scope of the present invention. For example, the invention may be applied to sprayers other than those carried or trailed by tractors or other vehicles, and is not limited to agricultural sprayers. In fact, the invention is broadly applicable to a wide variety of uses where a boom or other elongate member is liable to damage by contact with an obstruction during movement of the elongate member, or the obstruction, or both.

The locking means, hinge means and sensor means may take a variety of different forms. The locking means may incorporate overload release means, operable to free the boom or equivalent when subjected to bending forces exceeding a predetermined magnitude in the event of failure of the sensor means, although alternatively, the locking and sensor means could be designed to "fail-safe", i.e. release the locking means in the event of failure of the sensor means.

Referring to Figure 2, means may be provided, or the geometry of the mounting of the boom may be arranged, to avoid the necessity of adjusting the length of the trip wire should the elevation of the boom be changed significantly by means of the linkage 9.

Instead of, or in addition to, inclining the hinge axis 5e as shown in Figures 2 and 3, a relatively light spring or equivalent may be provided to return the boom to its normal latched operating position after breakback, or, alternatively, the boom may be returned by the operator.

If the need arises, sensor means could be mounted above and/or below the booms.

The sensor means could be mounted on the body of the sprayer instead of, or in addition to on the boom.

The central boom - support frame 3 may be mounted on a suspension system carried by the tractor 1 or other vehicle, instead of being fixed relative to the latter.

Claims (14)

1. A mobile spray appliance or other boomcarrying appliance, having a boom support and a boom mounted from the support for swinging movement relative to the latter, means for normally positively locking the boom in an operative position against such relative swinging movement, and sensor means positioned to detect the presence of an obstruction in the path of the boom and operable, upon such detection, to cause the locking means to release to free the boom for said relative swinging movement.

2. A boom or other elongate member for attachment to a mobile appliance, such as an agricultural spray appliance, the elongate member having mounting means at or adjacent one end thereof for mounting the elongate member from the appliance so as to permit swinging movement of the elongate member relative to the appliance, means operable to positively releasably lock the elongate member in an operative position against such swinging movement, and sensor means carried by the elongate member, operable to detect the presence of an obstruction proximate the elongate member and;upon such detection, to release the locking means and thereby permit the said swinging movement of the elongate member.

3. Apparatus as claimed in claim 1 or 2, wherein the sensor means is mounted on the boom or elongate member, forward of at least the leading edge or face thereof in the normal direction of travel of the appliance, so as to detect an obstruction and release the locking means before the obstruction strikes the boom or elongate member.

4. Apparatus as claimed in claim 3, wherein the sensor means is operable to effect detection along at least a major proportion of the length of the boom or elongate member, and is also effective to detect obstructions located beyond but adjacent the free end of the boom or elongate member.

5. Apparatus as claimed in claim 3 or 4, wherein the locking means includes a displaceable locking member, and means operable normally to resiliently bias the locking member into its locking condition, and wherein the sensor means comprises a tensioned elongate flexible element connected to the locking member and operable to displace the locking member against the action of its biasing means into an unlocking condition upon deflection of the elongate element by engagement of an obstruction therewith.

6. Apparatus as claimed in claim 5, wherein the force required to deflect the elongate element into a locking member- unlocking condition is significantly less than the force normally retaining the boom or elongate member against swinging movement from its operative position.

7. Apparatus as claimed in claim 3 or4, wherein the locking means includes a displaceable locking member, and means operable normally to bias the locking member into its locking condition, and wherein the sensor means comprises a proximity sensing arrangement and a circuit arrangement coupling the locking member to the proximity sensing arrangement whereby the sensing arrangement, upon sensing an obstruction in its proximity, is operable to release the locking member for displacement into an unlocking condition.

8. Apparatus as claimed in any preceding claim, including means normally operable to swing the boom or elongate member to its operative position after deflection therefrom and in the absence of an obstruction.

9. An arrangement for protecting a boom or other elongate member of a mobile appliance, such as a spray appliance, against damage due to collision of the elongate member with an obstruction during normal travel of the appliance, the arrangement comprising means for hingedly interconnecting the elongate member with a support therefor, releasable locking means operable to normally positively lock the hinge means against hinging movement, sensor means intended to be carried by the elongate member, and means for inter-connecting the sensor means and locking means whereby, in operation, detection of an obstruction by the sensor means is operable to release the locking means and free the hinge means.

10. A boom-protection arrangement substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

11. A boom-protection arrangementsubstantially as herein before described with reference to Figure 4 of the accompanying drawings.

12. An arrangement as claimed in claim 11, modified substantially as hereinbefore described with reference to Figure 5, or Figure 6, or Figure 7 of the accompanying drawings.

13. A mobile spray appliance incorporating an arrangement as claimed in any of claims 9 to 12.

14. A mobile agricultural spraying vehicle incor porating apparatus as claimed in any preceding claim.