GB2534391A

GB2534391A - A motion regulation system to control relative motion between a vehicle and a boom mounted to said vehicle

Info

Publication number: GB2534391A
Application number: GB1501036.6A
Authority: GB
Inventors: Mcavoy Paul
Original assignee: HOLME FARM SUPPLIES Ltd
Current assignee: HOLME FARM SUPPLIES Ltd
Priority date: 2015-01-21
Filing date: 2015-01-21
Publication date: 2016-07-27
Anticipated expiration: 2035-01-21
Also published as: GB201501036D0; GB2534391B

Abstract

A motion regulation system to control relative motion between a vehicle and a boom structure mounted to the vehicle. The boom structure comprises two booms that are mounted on opposite sides of a central mount; the two booms being rotatable relative to the central mount and to one another. The central mount is mounted to the vehicle to allow relative rotation between the vehicle and the central mount. The motion regulation system comprises two gas bags(air/hydraulic springs) connected to and arranged between the central mount and the vehicle; and means to determine that the vehicle has or is about to roll relative to the boom structure or visa-versa, and in response to alter the pressure of gas within one or both of the gas bags. Preferably the system comprises means to sense and control the gas pressure within at least one gas bag. Preferably there are means to calculate average gas pressure and to adjust accordingly. Preferably there is a conduit between the gas bags to allow gas to flow between the bags to equalise pressure. Preferably there are means to detect a change in the relief of the ground in front of the vehicle.

Description

A Motion Regulation System to Control Relative Motion Between A Vehicle and A Boom Mounted to Said Vehicle Delivery of liquid agricultural products, such as biocides and fertilizers onto crops is commonly performed using a vehicle such as a tractor or similar carrying a boom that extends from either side of the vehicle.

To ensure even coverage of the agricultural product, it is important that the height of the boom is controllable so that its distance above the ground/crop remains the same whilst the vehicle is moving. Each side of the boom can move independently of the other, usually through rotation relative to a central boom frame. This compensates when the ground has an uneven gradient across the length of the boom. Control of this process is typically achieved using sensors mounted to the boom that detect the distance of each side of the boom from the ground, and a control system that operates in response to signals received from the sensors to move either or both sides of the boom.

The tracks that the vehicle follows through a field, also known as wheelings, often become rutted and uneven with use. This can cause significant and aggressive roll (rotation through axis running from front to back of vehicle) of a vehicle travelling along the tracks that is not representative of the lay of the ground across the length of the boom. To minimise the effect that the vehicle's roll has on the orientation of the boom, the boom is pivotally mounted to the vehicle so that the vehicle and boom may rotate relative to one another.

This arrangement works well where each side of the boom is in a similar orientation with respect to the central boom frame. A problem arises, however, when it is necessary to rotate and/or hold the sides of the boom at different orientations, e.g. one side up and the other side down, as this tends to urge the boom frame to rotate about the pivot with the vehicle causing each side of the boom to move away from the -2 -desired orientations. The control system tries to correct for this by rotating each side of the boom relative to the central portion which in turn urges the boom to rotate further about the pivot. This cycle repeats until the sides of the boom have been rotated relative the central frame to their extreme positions leaving the boom keeled over to one side.

To compensate for this, prior art linkages include cylinder shock absorbers and/or coil tension springs mounted between the vehicle and the boom frame to provide a centralising force to counter the tendency of the boom to rotate about the pivot when either side of the boom is being rotated relative to the other. A problem with this arrangement is that the shock absorbers, and to a lesser extent the coil tension springs, transfer roll movements of the vehicle to the boom frame negating the benefit of pivotally mounting the boom to the vehicle.

A refinement of this system includes a linear ram associated with the vehicle frame and an inclinometer arranged to sense the roll orientation of vehicle. The ram controls the position of the connection point of the coil tension springs to the boom frame and moves the connection point in response to a detected roll of the vehicle so that that connection point remains directly below the pivot point. This compensates for the roll of the vehicle by controlling the tension in the springs; however, this system is complicated and expensive to install. Additionally this arrangement is not effective to prevent the boom rotating when one side is raised/lowered quickly (e.g. to lift in response to a sudden incline of the ground) as the vehicle may not have rolled over.

A further development has been to mount air bags between the vehicle and the boom frame. This improves the ride performance of the boom by enabling the vehicle to roll relative to the boom more freely as compared with springs. During a roll motion of the vehicle the boom will cause the air bag to compress without providing a resistive force sufficient to transfer the roll motion to the boom frame. -3 -

Notwithstanding the improvement properties of this linkage, it does not provide a complete solution as there still exists the problem of roll transfer to the boom during an aggressive roll of the vehicle or where the roll angle is large.

The present invention was conceived with the aim of providing a system that allows the vehicle to roll freely without affecting the orientation of the boom, and whilst stabilising the boom when one side is lifted relative to the other.

According to the invention there is provided a motion regulation system to control relative motion between a vehicle and a boom structure mounted to the vehicle; the boom structure comprising two booms that are mounted on opposite sides of a central mount; the two booms being rotatable relative to the central mount and to one another; the central mount being mountcd to the vehicle such as to allow relative rotation between the vehicle and the central mount; the motion regulation system comprising two gas bags connected to and arranged between the central mount and the vehicle; and means to determine that the vehicle has or is about to roll relative to the boom structure or visa-versa, and in response to alter the pressure of gas within one or both of the gas bags.

By varying the pressure within one or both of the gas bags, it is possible to compensate for roll of the vehicle to minimise or eliminate transfer of the roll to the 20 boom.

In a preferred embodiment, the motion regulation system comprises a pump being operable to inflate the gas bags and an exhaust that can be opened or closed by means of a valve to allow gas to be released from either or both bags. -4 -

The gas bags are preferably arranged on either side of the pivot point of the boom to the vehicle. The gas bags are preferably arranged with their compression/expansion axes substantially aligned with a tangent to a circle centred about (and favourable in a plane normal to) the axis of rotation of the boom to the vehicle. It is also preferred that the gas bags are spaced the same distance from the axis of rotation of the boom to the vehicle.

It is preferred that the motion regulation system comprises a sensor to sense the gas pressure within at least one of the gas bags and means to control the pressure of gas within one or both of the gas bags in response to a signal received from the sensor.

More preferably there are sensors to sense the gas pressure in each of the two gas bags.

It is preferred that motion regulation system comprises a conduit that provides fluid connection between the two gas bags, and means, such as a valve, to control flow of fluid through the conduit.

In use a pump is preferably used to inflate the gas bags to a desired pressure that is partly dependent upon the weight/inertia of the boom. The conduit may then be closed to isolate the gas bags during normal operation.

During a substantial roll of the vehicle, the pressure in one of the gas bags will increase significantly as a consequence of its compression, in this state the compressed gas bag tends to exert greater resistive force to further movement of the boom relative to the vehicle and thus transfers the vehicle's rotation to the boom. It is therefore preferred that the system has means to sense that the pressure within an air bag has increased and in response to reduce the pressure within said bag. By doing this the force required to compress the bag further is diminished thereby allowing the vehicle to roll to a greater angle with reduced or no transfer of roll to the boom. -5 -

In a preferred embodiment, the motion regulation system comprises means to alter the gas pressure within one or more of the gas bags in consequence of detecting a variance in the gas pressure between the gas bags because one of the bags has been compressed and the other expanded. This provides an effective means of determining that the vehicle has rolled relative to the boom. This avoids the need to activate the means to alter gas pressure based upon a pre-determined specific pressure value within either gas bag which could be problematic as specific values are likely to depend upon the specific starting pressure within the bags and the temperature of the gas.

Preferably the motion regulation system comprises means responsive to detecting a variance in the gas pressure between the gas bags, and in consequence of said detection, to substantially equalize (or bring towards equal) the pressure within the gas bags.

It is preferred that in response to detecting a variance in the gas pressure between the gas bags the conduit between the gas bags is opened to allow flow of gas there-between. This provides a quick and convenient means of balancing the pressures between the gas bags.

It is preferred that the motion regulation system comprises means to calculate the average gas pressure within the gas bags and to inflate or deflate the gas bags if the calculated average pressure is above or below a predetermined level. A primary use of this feature is to identify that one or both of the gas bags have partially deflated because of a leak. By calculating the average pressure it is possible to identify that gas has leaked from at least one of the bags without the need to account for pressure variance between the gas bags because the vehicle is in a rolled state.

It is preferred that during an operation to inflate or deflate the gas bags the conduit connecting the bags is opened in order that the gas bags will pressurise proportionally to the roll state of the vehicle at the time of inflation/deflation. -6 -

Improved roll compensation may be provided by identifying that the vehicle has or is about to roll before there is a change in the pressure in the gas bags. To this end it is preferred that the motion regulation system comprises means to detect a change in the relief of the ground that would cause the vehicle to roll and in consequence to said detection to vary the pressure in one or more of the gas bags.This may be done by providing means to sense a change in gas pressure in a gas bag forming part of a suspension system of the vehicle. A change in gas pressure would be expected when the vehicle's wheel moves away from or towards the vehicle's chassis.

An alternative or complementary means to provide forewarning may include the use of a sensor mounted towards or at the front of the vehicle arranged to detect relative changes in the topography of the ground in front of the vehicle. e.g. mounted in front of the left and right wheels.

It is also preferred that the motion regulation system comprises means to identify that a boom is moving, e.g. rotating, relative to the central mount and in response to maintain isolation of the gas bags. This ensures that the pressure within the gas bags is not rebalanced during movement of the boom which would diminish the centralising force provided by the gas bags.

The invention will now be described by example with reference to the following drawings in which: Figure 1 is rear view schematic of a tractor carrying a boom for delivery of an agricultural product over the ground Figure 2 is a rear ew of the boom frame, support frame and air bag linkage; Figure 3 is a schematic view of the system used to regulate motion between of the tractor and the boom frame; -7 -Figure 4 is a schematic view of a tractor carrying an unbalanced boom.

Figure 5 is a rear view schematic of a tractor carrying a boom shown with the tractor rolled over to the right Figure 6 is a rear view schematic of a tractor carrying a boom shown with the tractor rolled over to the left; Figure 7 is a side view schematic of a tractor carrying a boom showing means to detect roll of the tractor; and Figure 8 is a plan schematic of the tractor of Figure 7.

Referring to Fig 1 there is shown schematically a tractor, self propelled sprayer or similar such vehicle 1 having mounted at its rear a support frame 2 that includes a pivot pin/trunnion 3. Supported about the pivot pin 3 is a boom frame 4. The boom frame 4 is free to rotate about the pivot pin 3 relative to the support frame 2 and vehicle 1.

A hydraulic mechanism associated with the vehicle 1, not shown but well known to the skilled person, is provided to enable the support frame 2, and in consequence the boom frame 4, to be raised or lowered relative to the ground.

Mounted to either side of the boom frame 4 are booms 5A 5B. Each boom 5A 5B is mounted to the boom frame 2 by upper and lower hydraulic rams 6 that can be operated to rotate the booms 5A 5B relative the boom frame 4. The booms 5A 5B may be rotated independently of one another so that the booms have different orientations with respect to the boom frame 4 as illustrated in Fig 4.

Mounted between the support frame 2 and boom frame 4 are two air bags 7. The air bags 7 are of a form commonly used in heavy vehicle suspension systems, -8 -comprising has two parts that are mounted to flanges 2A, 4A on the support frame 2 and boom frame 4 respectively. The two parts of each air bag 7 are connected by a flexible bellow element that is filled, when in use, with air at above ambient pressure.

The air bags 7 are positioned on either side of the pivot pin 3 so that rotation of the support frame 2 or boom frame 4 in either a clockwise or anti-clockwise direction about pivot 3 will cause one of the air bags 7 to be compressed and the other to be stretched.

The air bags 7 are orientated so that their axes of compression/extension lie substantially on a tangent of a circle centred about and in a plane normal to the axis of pivot pin 3. Additionally, the distance of the air bags 7 from the pivot pin is substantially the same.

As illustrated in Fig 3, the air bags 7 form part of a system that comprises a pump 9 for pumping air from an inlet 10 to pressurise the air bags 7A 7B, an exhaust 11, a valve 12 to control flow of gas to the bags 7A 7B from the inlet 10, a valve 13 to control flow of air out of the exhaust 11; two pressure sensors 14A 14B that sense the pressure of the air within the respective air bags 7A 7B and produce signals indicative thereof.

The system also comprises a cross-over conduit 15 that provides fluid connection between the airs bags 7A 7B and a cross-over valve 16 that controls the flow of fluid through the cross-over conduit 15.

Each of the inlet, outlet and cross-over valves 12, 13, 16 is operated by a solenoid mechanism.

A controller 17 is arranged to receive signals from the sensors 14A 14B and in response to control the inlet, outlet and cross-over valves 12, 13, 16. The controller -9 - 17 is programmed to perform two primary functions using the signals received from the sensors 14A 14B described below.

The functions of the controller 17 may be provided by programmed circuitry using techniques familiar to those skilled in the art.

One function of the controller 17 is to determine the mean average of the air pressures within the air bags 7A 7B and to compare the determined average with a threshold value or range held by the controller 17. If the determined average is below the threshold value or range, which is indicative of air having leaked from one or both of air bags 7A, 7B, the inlet valve 12 and cross-over valve 16 are opened and the pump 9 operated (if not on continuously) to pumped air from the inlet to into the two air bags 7A 7B. The controller 17 causes both the inlet valve 12 and cross-over valve 16 to be closed once the preset valve or range has been reached.

Similarly, if the determined mean average pressure is below the threshold value or range, the controller 17 operates outlet valve 13 and preferably cross-over valve 16 to allow air to be expelled through exhaust 11. Alternatively, the cross-over valve 16 may be temporarily opened to balance the pressures within the air bags 7A 7B after the mean average pressure value has fallen to or within the threshold value/range.

Because the design of air bags used for this purpose are known to leak air over a period of a few hours, the inflation process may need be instigated each time the vehicle is started up after a period of non-use, or if used continuously for more than a few hours.

The controller 17 also determines from the signals derived from sensors 14A 14B a value indicative of the variance between the pressures within the two air bags 7A 7B. The value may be determined for example as the modulus of the pressure value in one of the bags subtracted from the pressure value within the other bag. Nevertheless, -10 -various other methods may be used for example by determining the range of the pressures from a mean pressure value.

If the value indicative of variance is greater than a threshold variance value held by the controller 17, the controller 17 causes solenoid cross-over valve 16 to be opened allowing the pressures within the airbags 7A 7B to equalise. The cross-over valve 16 is closed either after the value indicative of variance is determined to have fallen to equal or below the threshold variance value, or because the equalisation process typically occurs very quickly, a set time period after opening long enough to allow substantial equalisation to occur.

As shown in Fig 3, the system also comprises a user interface 18 connected to the controller 17. In a preferred embodiment, the user interface 18 is located in the cab of vehicle for easy access of the vehicle operator. The user interface 18 may thus be remote from the controller 17, though alternatively the controller 17 and control unit 18 may be formed as a single unit. The user interface 18 may comprise means to allow the vehicle's operator to switch on/off the motion regulation system, it may also display information to the operator, e.g. an alert that equalizing of the air bags 7A 7B is taking place or that the air bags are being inflated, it may also display the pressures within the air bags 7A 7B.

When the system is activated, and assuming the vehicle is fully upright and the booms 5A 5B are balanced, the controller 17 will cause both air bags 7A 7B to be inflated to a preset operating pressure. Where the vehicle is not upright, the average pressure of the air bags will be at the preset operating pressure.

The preset operating pressure needs to be sufficient that the bags 7A 7B provide a centring force that counters a torque force on the boom frame 4 caused by non identical movement of either side of the boom 5A 5B relative the boom frame 4 that would otherwise cause the boom frame 4 to rotate. Such movement being a result, for example, of lifting only one boom up so that the booms adopt an non balance arranged as shown for example in Fig 4. it is therefore preferred that the system comprises means to keep the bags 7A 7B isolated when it is detected that either boom 5A 5B is rotating relative to the boom frame 2.

Equally, the bags 7A 7B must compress/stretch to absorb the roll movement of the vehicle 1 rather than transfer the roll motion to the boom frame 4. The preferred operating pressure is also dependent upon the weight and/or length of the booms SA 5B. Longer/heavier booms benefit from larger air bag pressures; the greater inertia of the booms 5A 5B counter-acting the tendency for the higher pressured bags to transfer roll. The ideal pressure for any particular boom can be found through straightforward trial and error experimentation.

Figure 5 illustrates an instance in which the chassis vehicle 1 has rolled clockwise (as viewed from behind the vehicle) from upright as a consequence of the vehicle I passing over uneven ground 100. The support frame 2 having an orientation fixed relative to the vehicle adopts the orientation of the vehicle chassis. Because the boom frame 4 is pivotally mounted to the support frame 2 about pivot pin 3, the aforementioned rotation movement is not imparted to the boom frame 4.

The relative movement of support frame 2 to the boom frame 4 causes the left hand air bag 7A to be partly compressed as the distance between the frames 2, 4 on the left side decreases whilst the right hand air bag 7B is stretched of the increased distance between frames on the right hand side of the pivot pin 3. This results in an increase in the pressure within the left hand bag 7A and a corresponding decrease in pressure within the right hand bag 7B.

Conversely, if the vehicle 1 rolls anticlockwise, as illustrated in Fig 6, the relative movement of the support frame 2 to the boom frame 4 causes the right hand air bag 7A to be partly compressed as the distance between the frames 2, 4 on this side decreases whilst the left hand air bag 7B is stretched resulting in a decrease in the pressure within the left hand bag 7A and a corresponding increase in pressure within the right hand bag 7B.

If the tractor rotates through a large roll angle and/or rolls aggressively i.e. with a large rotational velocity sufficient to cause one of the airbags to compress enough that the pressure within it increases to an extent that the variation between the pressures within the airbags 7A 7B is above the threshold value, the controller 17 temporarily opens crossover valve 16 allow the pressures within bags 7A 7B to equalise. The valve 16 is then closed to isolate the airbags 7A 7B again. This action has the effect of reducing the force required to further compress the partly compressed air bag to allow further relative rotation between the vehicle 1/support frame 2 and the boom frame 4 whilst reducing the transfer the torque exerted upon the boom frame 4 that would otherwise urge it to rotate with the vehicle 1.

Figures 7 & 8 illustrate schematically a tractor 1 having air suspension comprising air bags 20 that allow relative vertical movement between wheels 30 of the vehicle and the tractor's chassis 50. There is typically an air bag 20 associated with each wheel 20. The vehicle 1 is equipped with sensors 60 arranged to sense the pressure of air within at least one air bag 20 on the left and right sides of the tractor 1. In Figures 7 & 8 the sensors are associated with the air bags 20 of the rear wheels, though it may instead or additionally be the front wheels.

Signals from the sensors 20 indicative of the pressures within the respective air bags 20 are received by the controller 17. The controller 17 determines from the received signals a change of pressure within the air bag(s) on one side of the tractor 1 indicative that the tractor 1 has started or is about to roll to one side, for example because that the wheel has either being forced closer to the chassis by raised ground or falling away from the chassis as the wheel is falling into a depression. In response the controller 17 varies the pressure in at least one of the air bags 7A 7B between the support frame 2 and boom frame 4 to pre-empt the vehicle's roll. It is believed that this method may provide superior roll inhibition to the boom over the reactive method.

In addition or as an alternative to the sensors 60, the tractor I may be equipped with sensors 70, for example ultra sonic sensors, mounted immediately in front of the left -13 -and right front wheels to detect a change in the topography of the ground in front of the wheels, and in changes in topography that are not occurrent in front of both the left and right side wheels and such could cause the vehicle to roll.

Although the sensors 60 are shown residing in the air bags 20 this is not necessary so long as the sensors are able to sense the pressure of the air within its designated bag.

Rather than equalising the pressure within the air bags 7A 7B through operation of the cross-over valve 16 it would be possible instead to reconfigure the system so that the pressure within the two bags 7A 7B could be varied whilst remaining isolated from one another, e.g. pressurising one bag whilst simultaneously deflating the other.

This method is not preferred because of the additional components required to make it function, and also because it is believed that the process of deflating and inflating the air bags individually would take longer because of the need of a feedback process to ensure the bags are inflated/deflated to the correct level.

The invention is equally applicable to dedicated sprayer vehicles either self propelled or in trailer form. Although the invention has been described in conjunction with a vehicle having discrete wheels, the invention may be equally applicable for use with vehicles that utilise continuous tracks.

In a variation to system, the solenoid controlled inlet valve 12 may be replaced with a one-way valve.

More than two air bags 7A 7B may be mounted between the support frame 2 and boom frame 4.

Although not preferred for reasons of expense, a gas or gas mixture other than air may be used to inflate or deflect the air bags.

-14 -It is possible that the invention may be used with arrangements in which the boom frame is mounted to the vehicle about two pivots, such arrangements being known in the art.

Claims

-15 -Claims 1. A motion regulation system to control relative motion between a vehicle and a boom structure mounted to the vehicle; the boom structure comprising two booms that are mounted on opposite sides of a central mount; the two booms being rotatable relative to the central mount and to one another; the central mount being mounted to the vehicle such as to allow relative rotation between the vehicle and the central mount; the motion regulation system comprising two gas bags connected to and arranged between the central mount and the vehicle, and means to determine that the vehicle has or is about to roll relative to the boom structure or visa-versa, and in response to alter the pressure of gas within one or both of the gas bags.
2. A motion control system according to claim 1 comprising a sensor to sense the gas pressure within at least one of the gas bags and means to control the pressure of gas within one or both of the gas bags in response to a signal received from the sensor.
3. A motion regulation system according to claim 2 comprising sensors to sense the pressure of gas in each of the two gas bags.
4. A motion regulation system according to claim 1, 2 or 3 comprising means to calculate the average gas pressure within the gas bags and to inflate or deflate one or both gas bags if the calculated average pressure is below or above a predetermined level.

-16 -
5. A motion regulation system according to claim 1, 2 or 3 comprising means to calculate the average gas pressure within the gas bags and to inflate both gas bags if the calculated average pressure is below a predetermined level.
6. A motion regulation system according to any previous claim comprising a conduit to provide fluid communication between the gas bags
7. A motion regulation system according to claim 6 comprising means responsive to a determination that the vehicle has or is about to roll relative to the boom structure or visa-versa, to open the conduit to allow gas to flow between the air bags.
8. A motion regulation system according to any claim 1 -7 comprising means to alter the gas pressure within one or more of the gas bags in consequence of detecting a variance in the gas pressure between the gas bags.
9. A motion regulation system according to claim 8 comprising a conduit between the gas bags and means to allow gas to flow through the conduit between the gas bags to equalize the pressure between the bags upon
10. A motion regulation system according to any previous claim comprising means to detect a change in the relief of the ground in front of the vehicle liable to cause the vehicle to roll and in consequence to said detection to vary the pressure in one or more of the gas bags.
11. A motion regulation system according to claim 10 comprising means to sense a change in gas pressure in a gas bag forming part of a suspension system of the vehicle.12 A motion regulation system according claim 10 or 11 comprising a sensor mounted to the vehicle and arranged to detect the distance between the vehicle's chassis and the ground immediately in front of the vehicle's left and right wheels.13. A motion regulation system according to any previous claim comprising means to identify that a boom is moving relative to the central mount and in response to maintain isolation of the gas bags.