Agricultural implement and method

Abstract

An agricultural implement (12) has a frame supported on pneumatic tires (32) and row units (20) carried by the frame. The row units are movable between a lowered position in contact with the ground and a raised position clear of the ground. At least one weight sensor generates a signal indicative of the weight supported by at least one the tires. A central tire inflation system (CTIS) includes a processor and non-transitory computer-readable storage medium storing instructions. The CITS sets a system minimum tire pressure based on weight data received from the weight sensor when the row units are in the raised position. The CTIS subsequently monitors and adjusts the pressure of the air in the tires (32) when the implement is used in the field without allowing the tire pressures to fall below the set system minimum tire pressure.

Description

AGRICULTURAL IMPLEMENT AND METHODCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not applicable.FIELD

[0002] Embodiments of the present disclosure relate generally to agricultural implements having a central tire inflation system and to methods of operating such agricultural implements.BACKGROUND

[0003] Central tire inflation systems CTIS (also referred to as central tire pressure control systems) have been developed which allow tire pressures on apparatus, such as a vehicle or an agricultural implement, to be automatically monitored and adjusted centrally. For agricultural applications, it is desirable to be able to optimise tire inflation pressures for use in different environments. For example, for use in a field it is often desirable to use lower tire inflation pressures. This helps to spread the weight of the apparatus, reducing soil compaction, and maximises grip. Whereas for use on a road or other hard surfaces, higher tire pressures provide stability, increased fuel efficiency and minimise tire wear. Accordingly, central tire inflation systems have been adopted for use on various agricultural apparatus including tractors, towed implements (such as planters, strip till rigs, air seeders / drills, and the like), sprayers, combined harvesters, forage harvesters and the like. CTIS can be used to monitor and adjust tire pressures whilst the implement is in use to maintain an appropriate tire pressure for the current operating environment (e.g., field use or road use). CITIS can also be used to adjust the tire pressures when transitioning between road and field use. The known CTIS used on agricultural implements will generally be configured to ensure that the tire pressures stay within the tire manufacture's recommendations for the weight supported by the tires and the speed of the implement over the ground so that the tires are not damaged. Within those limits, the known CITS will generally try to maintain pressure in the tires low as possible for field use and as high as possible for road use.

[0004] Towed agricultural implements often carry consumables in one or more reservoirs that are dispensed as the implement traverses a field. For example, a planter will usually carry seed which are dispensed as the planter traverses the field and may also carry fertiliser which is also dispensed. Accordingly, the overall weight of the implement varies over time, reducing as the consumables are dispensed and increasing when they are replenished. Known CTIS will monitor the changing weight and adjust the tire pressures accordingly.

[0005] In planters and other similar agricultural implements which have row units that are moveable between an in-use position in which the row units are lowered for contact with the ground and a raised position in which the row units are lifted clear of the ground, the weight that is supported by the tires increases significantly when the row units are raised compared to when they are in the lowered in-use position.BRIEF SUMMARY

[0006] In an aspect of the disclosure, there is provided an implement for working an agricultural field, the implement comprising a frame supported on the ground by a plurality of tires and a plurality of row units carried by the frame, the row units configured for movement between a lowered position in which they are brought into contact with the ground and a raised position in which they are lifted clear of the ground, and at least one weight sensor for generating a signal indicative of the weight supported by at least one the tires. The implement having a central tire inflation system for monitoring and adjusting the air pressure of the tires, the central tire inflation system including at least one processor and at least one non-transitory computer-readable storage medium storing instructions thereon that, when executed by the at least one processor, cause the central tire inflation system to receive weight data indicative of the weight supported by the at least one the tires from the at least one weight sensor when the row units are in the raised position and to determine and set a system minimum tire pressure based at least in part on the received weight data and to subsequently monitor and adjust the pressure of the air in the tires without allowing the tire pressures to fall below a currently set system minimum tire pressure.

[0007] The system minimum tire pressure can be set to that required to support the weight of the implement with the row units raised without damaging the tires and may be set in accordance with recommendations of a manufacturer of the tires. This can be beneficial when the row units are raised to make a turn at the end of a run across a field resulting in asudden increase in the load supported by the tires. The set system minimum tire pressure may be stored in the at least one non-transitory computer-readable storage medium or some other computer readable memory device accessible to the processor.

[0008] The implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to receive row unit position data and to initiate setting of the system minimum tire pressure on receipt of row unit position data indicative that the row units are in a raised position.

[0009] The implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to receive data indicative of the ground speed of the implement and to set the system minimum tire pressure based at least in part both on the weight data and the speed data. The implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to set the system minimum tire pressure based at least in part on the weight data and a predefined minimum speed in the event the speed data indicates that the implement is travelling at or below the predefined minimum speed. The predefined minimum speed may be in the region of 10 to 16 kph, for example. Speed data may be acquired from a speed sensor which may be provided on the implement or on vehicle towing the implement.

[0010] The implement may have more than one weight sensor, each weight sensor for detecting a weight indicative of the weight supported by an associated one of the tires, and the implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to set the system minimum tire pressure based at least in part on the weight data received from the weight sensors that is indicative of the highest weight supported by any one of the associated tires. The implement may have a weight sensor associated with each of the tires, each weight sensor for detecting a weight indicative of the weight supported by its associated tire.

[0011] The tires on the implement may be assigned to at least two distinct groups and the implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to determine and set a respective system minimum tire pressure for each group based at least in part on weight data received from a respective weight sensor associated with at least one tire in that group. Where any given group includes more than one tire and the implement has a respective weight sensor associated with each tire in the group, the implement may further include instructions that,when executed by the at least one processor, cause the central tire inflation system to determine and store a respective system minimum tire pressure for that group based at least in part on weight data received from the respective weight sensors associated with the tires in that group that is indicative of the highest weight supported by any one of the associated tires. The central tire inflation system may be configured to enable the pressure of the tires in each group to be monitored and adjusted independently of the tires in the other group(s).

[0012] The implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to update the set system minimum tire pressure periodically.

[0013] The implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to update the set system minimum tire pressure each time the row units are raised.

[0014] The implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to limit the amount by which the system minimum tire pressure is changed each time it is updated. In an embodiment, the implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to only permit the system minimum tire pressure to be changed by up to a maximum percentage of the currently set system minimum tire pressure or up to a maximum percentage of an average of the currently set system minimum tire pressure and a predetermined number of previously set system minimum tire pressures each time the system minimum tire pressure is updated.

[0015] The implement may further include instructions that, when executed by the at least one processor, cause the central tire inflation system to override a limitation on the size of the permitted change in the system minimum tire pressure depending at least in part on an input indicative of an operational status of the implement. For example, a change in system minimum tire pressure exceeding the usually allowed percentage change may be permitted when the system minimum tire pressure is set for the first time after consumables, such as seed and / or fertilizer, have been introduced on to the implement. Data indicative of an operational state in which the limitation on the size of the permitted change in the system minimum tire pressure can be overridden may be provided by one or more sensors and / or as a user input received through a user interface.

[0016] Subsequently monitoring and controlling the tire pressures without allowing the pressure in any of the tires to fall below the currently set system minimum tire pressure may comprise monitoring and adjusting the tire pressures as the implement traverses a field dependent at least in part on contemporaneous weight data and speed data to maintain the tire pressures as low as possible without falling below the currently set system minimum tire pressure and without falling below a minimum tire pressure required to prevent tire damage for the weight supported and implement ground speed. The required minimum tire pressure may be selected based on recommended tire pressure data for the tires, which may be provided by the tire manufacturer.

[0017] The implement may be selected form the group comprising an agricultural planter and an air seeder / drill.

[0018] In another aspect of the disclosure, there provided a combination of an agricultural implement according to the aspect set out above coupled to a towing machine, such as an agricultural tractor.

[0019] In an embodiment, at least some aspects of the CITIS may be provided on the towing machine. In an embodiment, part of a control system for the CITS, which may include a HMI and / or a speed sensor may be provided on the towing machine. In an embodiment, the CTIS controller may be provided on the towing machine.

[0020] In another aspect of the disclosure, there is provided a computer implemented method of automatically adjusting the tire pressures of an implement for working an agricultural field, the implement comprising a frame supported on the ground by a plurality of tires and a plurality of row units carried by the frame, the row units configured for movement between a lowered position in which they are brought into contact with the ground and a raised position in which they are lifted clear of the ground, the method comprising receiving weight data indicative of the weight supported by at least one of the tires when the row units are in the raised position from a weight sensor system and setting a system minimum pressure based at least in part on the received weight data, the method further comprising subsequently monitoring and controlling the tire pressures without allowing the pressure in any of the tires to fall below a currently set system minimum tire pressure.

[0021] The system minimum tire pressure can be set to that required to support the weight of the implement with the row units raised without damaging the tires and may be setin accordance with recommend tire pressure data, which may be provided by a manufacturer of the tires. This can be beneficial when the row units are raised to make a turn at the end of a run across a field resulting in a sudden increase in the load supported by the tires.

[0022] The method may comprise setting the system minimum tire pressure based at least in part both on the weight supported by the tires when the row units are raised and the speed of the implement across the ground. The method may comprise setting the system minimum tire pressure based at least in part on the weight supported by the tires and a predefined minimum speed in the event the implement is travelling at or below the predefined minimum speed. The predefined minimum speed may be in the region of 10 to 16 kph, for example.

[0023] The method may comprise updating the system minimum tire pressure periodically when the row units are raised. The system minimum tire pressure may be updated each time the row units are raised. This is beneficial in allowing the system minimum tire pressure to be updated where the weight of the implement with the row units raised varies, say as consumables carried by the implement are used up or replenished.

[0024] The method may comprise imposing a predefined limit on the amount by which the system minimum tire pressure can be changed each time it is updated. In an embodiment, the method may comprise only permitting the system minimum tire pressure to be changed by up to a maximum percentage of the currently set system minimum tire pressure or by up to a maximum percentage of an average of the currently set system minimum tire pressure and a predetermined number of previously set system minimum tire pressures. This may be advantageous in not allowing an excessive change in the system minimum tire pressure in the event of an anomalous detection of the weight supported by the tires or some other fault in the system. However, the method may comprise overriding the limitation on the size of the permitted change in the system minimum tire pressure depending on the operational status of the implement. For example, a change in system minimum tire pressure exceeding the usually allowed percentage change may be permitted when the system minimum tire pressure is set for the first time after consumables, such as seed and / or fertilizer, have been introduced on to the implement.

[0025] The tires may be assigned in at least two groups and setting a system minimum tire pressure may involve setting a different respective system minimum tire pressure for each group. For example, a planter may have a central section supported on theground by a plurality of central section tires and at least one wing section, with each wing section supported on the ground by at least one wing tire. In such an arrangement, the central section tires may be regarded as a first group and the wing tire or tires can be regarded as a second group. A system minimum tire pressure can be set for the central section tires based on the highest weight supported by any one of the central section tires when the row units are raised and a system minimum tire pressure for the wing section tires set based on the highest weight supported by any one of the at least one wing section tire when the row units are raised. The central tire inflation system may be configured to enable the pressure of the tires in each group to be monitored and adjusted independently of the tires in the other group(s).

[0026] Subsequently monitoring and controlling the tire pressures without allowing the pressure in any of the tires to fall below the currently set system minimum tire pressure may comprise monitoring and adjusting the tire pressures as the implement traverses a field dependent at least in part on the weight supported by the tires and the speed of the implement over the ground to maintain the tire pressures as low as possible without falling below the currently set system minimum tire pressure and without falling below a minimum tire pressure required to prevent tire damage for the weight supported and implement ground speed. The required minimum tire pressure may be selected based on recommended tire pressure data for the tires, which may be provided by the tire manufacturer.

[0027] Within the scope of this application it should be understood that the various aspects, embodiments, examples and alternatives set out herein, and individual features thereof may be taken independently or in any possible and compatible combination. Where features are described with reference to a single aspect or embodiment, it should be understood that such features are applicable to all aspects and embodiments unless otherwise stated or where such features are incompatible.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] One or more embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0029] FIG. 1 is a perspective view of a planter incorporating a CTIS according to an aspect of the disclosure;

[0030] FIG. 2 is a perspective view of components of the CTIS of FIG. 1 shown isolated from the remainder of the planter;

[0031] FIG.3 is a schematic representation of the CTIS of FIGS. 1 and 2; and

[0032] FIG. 4 is a schematic illustration of planter coupled to a towing machine in the form of a tractor, the combination including a CTIS according to an aspect of the disclosureDETAILED DESCRIPTION

[0033] The illustrations presented herein are not actual views of any implement, sensor, or portion thereof, but are merely idealized representations that are employed to describe example embodiments of the present disclosure. Additionally, elements common between figures may retain the same numerical designation.

[0034] The following description provides specific details of embodiments of the present disclosure in order to provide a thorough description thereof. However, a person of ordinary skill in the art will understand that the embodiments of the disclosure may be practiced without employing many such specific details. Indeed, the embodiments of the disclosure may be practiced in conjunction with conventional techniques employed in the industry. In addition, the description provided below does not include all elements to form a complete structure or assembly. Only those process acts and structures necessary to understand the embodiments of the disclosure are described in detail below. Additional conventional acts and structures may be used. The drawings accompanying the application are for illustrative purposes only, and are thus not drawn to scale.

[0035] As used herein, the terms "comprising," "including," "containing," "characterized by," and grammatical equivalents thereof are inclusive or open-ended terms that do not exclude additional, unrecited elements or method steps, but also include the more restrictive terms "consisting of" and "consisting essentially of" and grammatical equivalents thereof.

[0036] As used herein, the term "may" with respect to a material, structure, feature, or method act indicates that such is contemplated for use in implementation of an embodiment of the disclosure, and such term is used in preference to the more restrictive term "is" so as to avoid any implication that other, compatible materials, structures, features, and methods usable in combination therewith should or must be excluded.

[0037] As used herein, the term "configured" refers to a size, shape, material composition, and arrangement of one or more of at least one structure and at least one apparatus facilitating operation of one or more of the structure and the apparatus in a predetermined way.

[0038] As used herein, the singular forms following "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0039] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0040] As used herein, spatially relative terms, such as "beneath," "below," "lower," "bottom," "above," "upper," "top," "front," "rear," "left," "right," and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation depicted in the figures.

[0041] As used herein, the term "substantially" in reference to a given parameter, property, or condition means and includes to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met with a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, or even at least 99.9% met.

[0042] As used herein, the term "about" used in reference to a given parameter is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the given parameter).

[0043] Embodiments of the disclosure will now be described with reference to an agricultural planter 12. However, the teachings herein can be applied any agricultural implement configured to be towed by a tractor or other suitable vehicle, where the implement has a frame supported on the ground by a plurality of tires and a plurality of row units supported on the frame for movement between a lowered position in which they are brought into contact with the ground and a raised position in which they are lifted clear of the ground. Non-limiting examples of such agricultural implements include strip till rigs, air seeders / drills, and the like. In this regard, the term "row unit" should be understood ascovering any suitable unit which can be moved between a lowered position where it engages the ground and a raised position in which the amount of weight of the implement transferred to the ground through the unit is reduced in comparison to that transferred to the ground when the unit is in the raised position. As illustrated in FIG. 4, the disclosure is also relevant to CTIS on apparatus comprising a combination of a towed agricultural implement 12 and a towing vehicle or machine, such as a tractor 9.

[0044] With reference to FIGs. 1 and 2, an agricultural planter 12 is provided with a CTIS 10 and a weight distribution system 14.

[0045] The planter 12 includes a frame 16 and a hitch 18 for attachment to a tractor 9 or other towing vehicle or machine (Fig. 4). In the following, the towing vehicle will be assumed to be a tractor but it should be understood that references to a tractor can be replaced by any suitable vehicle or machine capable of towing the planter unless the context requires otherwise.

[0046] In the illustrated embodiment, the planter 12 is configured for planting row crop seeds and has a number of row units 20 mounted to a transverse toolbar 22 forming part of the frame. The toolbar in this embodiment is divided into three sections, a central section 22a and a pair of wing sections 22b, 22c, the wing sections located at opposite lateral ends of the central section 22a. Each section 22a, 22b, 22c has a two-part construction consisting of a main toolbar 24 and a secondary or seed toolbar 26 which holds the row units. The position of each of the row units 20 is independently adjustable relative to the respective secondary 26 and the position of each of the secondary 26 is adjustable relative to the respective main toolbar 24. The central section 22a extends in a transverse direction of the planter and the wing sections 22b, 22c are each movable between a working position as shown where they extend in the transverse direction, generally in-line with the central section 22a, and a transport or folded position in which they extend generally in a longitudinal direction X of the planter 12.

[0047] A planter 12 having multiple toolbar sections 22a, 22b, 22c according to the embodiment shown in the drawings can support many row units 20 and is particularly suitable for working large fields. However, the present disclosure is not limited to planters 12 or other implements having this number of toolbar sections. In other embodiments, a planter may have only one toolbar section for supporting a smaller number of row units or may have fewer or more than three toolbar sections. A planter in accordance with the disclosure could, forexample, have one, two, three, four, five or more toolbar sections. Furthermore, the disclosure is not limited to implements where each toolbar section has a two-part construction consisting of a main toolbar 24 and a secondary toolbar 26 which holds the row units. Accordingly, in other embodiments the, or each, toolbar section may comprise only a single toolbar to which the row units are mounted.

[0048] The planter 12 is supported for movement over the ground by a number of wheels 30, 30', each having a pneumatic tire 32. The main toolbar 24 of the central section is supported on four centre section wheels 30 arranged in two tandem pairs including a right front wheel 30a, a right rear wheel 30b, a left front wheel 30c, and a left rear wheel 30d. The main toolbar 24 of each wing section 22b, 22c is supported on a single wing wheel 30', denoted as 30'a, 30'b on either wing section. In other embodiments, each wing section may be supported by more than one wing wheel 30'.

[0049] The weight distribution system 14 includes fluid actuators (e.g., hydraulic cylinders) 40, each operative between the central section 22a of the toolbar and a respective one of the wing sections 22b, 22c to vary the weight distribution across the toolbar and hence the loading on the various wheels 30, 30'.

[0050] Each row unit 20 includes seed delivering elements such as seed hoppers 42 and seed metering discs of conventional design. Furthermore, main seed hoppers 44 and one or more storage tanks 46 for fluids (e.g., fertilizer and / or weedkiller) for delivery by the row units 20 may be supported on the frame 16.

[0051] The weight distribution system 40 and the seed and fluid delivery arrangements of the planter 12 are not described in detail as they are not relevant to the present disclosure.

[0052] The CTIS 10 includes a source of pressurised air 50, which may be an accumulator or reservoir, a manifold 52, and a rotary coupling 56 for each wheel 30, 30'. The accumulator 50 may be supplied with pressurised air from a pressurised air source which may be located on the tractor 9 or on the implement 12. In an embodiment, the planter 12 is towed by a tractor 9 having a pressurised air supply system connectable to the accumulator via a hose 58 and releasable connector 60 in a known manner. Alternatively, a compressor may be provided on the planter to supply the accumulator 58. This may be necessary for use with tractors not equipped with a suitable pressurised air supply. Such a compressor may behydraulically or electrically driven. It will be appreciated that any suitable source of pressurised air can be used, especially for applications other than a planter.

[0053] Each rotary coupling 56 fluidly connects a respective pneumatic wheel line 61 to an interior reservoir 62 of the pneumatic tire 32 on the respective wheel 30, 30'. In a known manner, each rotary coupling 56 enables air to flow into and out of the interior reservoir 62 to inflate and deflate the tire 32. In an embodiment, each rotary coupling 56 may be provided as part of a unit or weighing cell including a sensor for measuring the load on the wheel and hence the weight supported by a tire on the wheel.

[0054] Details of the CTIS will now be described with reference principally to FIG.3.

[0055] The main valve manifold 52 has a pressurised air supply passage 64 having an inlet 66 connected with the accumulator 50 by an air supply line 68 and an air exhaust passage 70 having an outlet 72. The air exhaust passage 70 is connected with an exhaust outlet or vent 94 through which air is exhausted to atmosphere. The exhaust outlet 94 may be termed an atmospheric exhaust outlet and may be connected with the outlet 73 of the air exhaust passage 70 by a fluid passage or line 104.

[0056] The main valve manifold 52 includes a number of valves configured to enable each of the wheel lines 61 (and hence the interior reservoir 62 of the respective tire 32 on the associated wheel 30, 30') to be selectively connected with the air supply passage 64 in order to inflate the respective tire 32 or with the air exhaust passage 70 in order to deflate the respective tire 32. All the valves in the main valve module may be electronically controllable two position solenoid valves movable between a closed position, as shown, in which flow through the valve is prevented and an open position in which flow through the valve is permitted. In the embodiment shown, the valves are each biased to the closed position and actuated by means of a solenoid to the open position. The valves in the main valve manifold are divided into a centre section module (indicated by broken line 74) which is used to regulate the pressure of the tires of the centre section wheels 30a, 30b, 30c, 30d, and a wing section wheel module (indicated by broken line 76) which is used to regulate the pressures of the tires of the wing wheels 30'a, 30'b.

[0057] The centre section module 74 has a first intermediate flow passage 78, a first inflation valve 80, and a first deflation valve 82. The first inflation valve 80 is operable in use to selectively connect the first intermediate flow passage 78 with the air supply passage 64 when open and to disconnect the first intermediate flow passage 78 from the air supplypassage 64 when closed. In a similar manner, the first deflation valve 82 is operable in use to selectively connect the first intermediate flow passage 78 with the air exhaust passage 70 when open and to disconnect the first intermediate flow passage 78 from them air exhaust passage 70 when closed. The centre section module includes four centre section wheel valves 84a, 84b, 84c, 84d, each being operative to selectively connect a respective one of the wheel lines 61a, 61b, 61c, 61d to the first intermediate flow passage 78 when open and to disconnect the respective wheel line from the first intermediate flow passage 78 when closed. By appropriate actuation of the first inflation valve 80, the first deflation valve 82, and the centre section wheel valves 84a, 84b, 84c, 84d, the interior reservoir of any one of more of the tires 32 on the centre section wheels can be connected to the air supply passage 64 to be inflated or to the air exhaust passage 70 to be deflated.

[0058] In normal use, the first inflation valve 80 and first deflation valve 82 remain closed and the wheel valves 84a-84d are opened so that the wheel lines 61a-61d are fluidly connected to the intermediate flow passage 78. In this configuration, the air pressures between the tires of the centre section wheels 30a-30d are equalised. If it is necessary to inflate the tires on the centre section wheels 30a-30d, the first inflation valve 80 is opened to connect the first intermediate flow passage 78 with the air supply passage 64 and the source of pressurised air 50 whilst the first deflation valve 82 remains closed. When the tires 32 on the centre section wheels reach the desired pressure, the first inflation valve 80 is closed. If it is necessary to deflate the tires 32 on the centre section wheels, the first deflation valve is opened whilst the first inflation valve 80 remains closed to connect the first intermediate flow passage 78 to the air exhaust passage 70 and hence the exhaust outlet 94 to atmosphere. When the tires 32 on the centre section wheels reach the desired pressure, the first deflation valve 80 is closed.

[0059] A first pressure sensor 86 may be fluidly connected to the first intermediate flow passage 78 to sense the pressure in the first intermediate flow passage 78. With the centre section wheel valves 84a-84d opened and the first inflation valve 80 and the first deflation valve 82 closed, the pressure in the first intermediate flow passage 78 is indicative of the pressure of the tires of the centre section wheels. Accordingly, the first pressure sensor 86 can be used to monitor the tire pressures of the centre section wheels 30a-30d.

[0060] The wing section module 76 is constructed and operates in a similar manner to the centre section module 74 but has only two wing section wheel valves 84'a, 84'b, onefor each of the wing wheels 30'a, 30'b. In alternative embodiments where the wing sections have more than one wheel each, the wing section module 76 will have a corresponding number of wing section wheel valves. The wing section module 76 has a second intermediate flow passage 78', a second inflation valve 80', and a second deflation valve 82'. The second inflation valve 80' is operable in use to selectively connect the second intermediate flow passage 78' with the air supply passage 64 when open and to disconnect the second intermediate flow passage 78' from the air supply passage 64 when closed. In a similar manner, the second deflation valve 82' is operable in use to selectively connect the second intermediate flow passage 78' with the air exhaust passage 70 when open and to disconnect the second intermediate flow passage 78' from the air exhaust passage 70 when closed. The wing section wheel valves 84'a, 84'b are each operative to selectively connect a respective one of the wing section wheel lines 61'a, 61'b to the second intermediate flow passage 78' when open and to disconnect the respective wing section wheel line from the second intermediate flow passage 78' when closed. By appropriate actuation of the second inflation valve 78', the second deflation valve 82', and the wing section wheel valves 84'a, 84'b any one or both of the tires 32 on the wing section wheels 30'a, 30'b can be connected to the air supply passage 64 to be inflated or to the air exhaust passage 70 to be deflated.

[0061] Operation of the valves in the wing section wheel module 76 to inflate or deflate the tires on the wing wheels 30'a, 30'b is similar to that of the centre section module 74. In normal use on a field, the second inflation valve 80' and second deflation valve 82' remain closed and the wing wheel valves 84'a and 84'b are opened so that the wheel lines 61'a and 61'b are fluidly connected to the second intermediate flow passage 78'. In this configuration, the pressures of the tires of the wing section wheels 30'a, 30'b are equalised. If it is necessary to inflate the tires on the wing section wheels 30'a, 30'b, the second inflation valve 80' is opened to connect the second intermediate flow passage 78' with the air supply passage 64 and the source of pressurised air 50 whilst the second deflation valve 82' remains closed. When the tires 32 on the wing section wheels reach the desired pressure, the second inflation valve 80' is closed. If it is necessary to deflate the tires 32 on the wing section wheels, the second deflation valve 82' is opened whilst the second inflation valve 80' remains closed to connect the second intermediate flow passage 78' to the air exhaust passage 70 and hence the exhaust outlet 94 to atmosphere. When the tires 32 on the wing section wheels reach the desired pressure, the second deflation valve 80' is closed.

[0062] A second pressure sensor 86' may be fluidly connected to the second intermediate flow passage 78' to sense the pressure in the second intermediate flow passage 78'. At least when the wing section wheel valves 84'a, 84'd are opened and the second inflation and deflation valves 80' 82' closed, the pressure in the second intermediate flow passage 78' is indicative of the pressure in the tires of the wing wheels 30'a, 30'b. Accordingly, the second pressure sensor 86' can be used to monitor the tire pressures of the wing wheels.

[0063] A third pressure sensor 86'' may be fluidly connected with the air supply passage 64 to monitor the air pressure in the air supply passage 64. The third pressure sensor 86'' can be used to monitor system pressure. For example, when the pressurised air is supplied by a towing tractor, the system pressure will need to be maintained above a predetermined minimum (e.g., 6.9 bar or 100 psi) as required to keep the air brakes on the tractor unlocked and / or to meet other system requirements.

[0064] The valves may be electronically controllable valves operatively connected with an electronic controller (indicated schematically at 90). The valves may be two position solenoid valves. The controller 90 may comprise, or be connected with a HMI, indicated schematically at 92. The HMI 92 may include a display screen visible to an operator of the machine and may include user input means. The display screen may be a touch screen through which the operator is able to provide inputs or other user input means may be provided which could be physically separate from the display screen. The controller 90 provides the control logic for the CTIS functionality. The controller 90 may be provided on the planter 12 or on a tractor to which the planter is connected and may be part of larger control system for the planter 12 and / or tractor. The controller 90 may include a first controller 90 on the planter and a second controller on the tractor. In an embodiment, the controller 90 is provided on the planter, or other agricultural implement, and is in communication with a HMI 92 on the tractor. However, in other embodiments, the controller 90 is not in communication with a HMI or the HMI may be for displaying for displaying functionality of the CTIS only. Where a HMI is provided on the tractor, this may be part of a control system of the tractor or it may a stand-alone display mounted in the tractor but not forming part of the original equipment of the tractor.

[0065] In one embodiment, the controller 90 comprises one or more processors, such as processor 90a, input / output (I / O) interface(s), and memory 90b, all coupled to one or more data busses. The memory 90b may include any one or a combination of volatile memoryelements (e.g., random-access memory RAM, such as DRAM, and SRAM, etc.) and non-volatile memory elements (e.g., ROM, hard drive, tape, CDROM, etc.). The memory 90b may store a native operating system, one or more native applications, emulation systems, or emulated applications for any of a variety of operating systems and / or emulated hardware platforms, emulated operating systems, etc. In one embodiment the memory comprises an operating system and CTIS (tire pressure) control software. It should be appreciated by one having ordinary skill in the art that in some embodiments, additional or fewer software modules (e.g., combined functionality) may be stored in the memory 90b or additional memory. In some embodiments, a separate storage device may be coupled to the data bus, such as a persistent memory (e.g., optical, magnetic, and / or semiconductor memory and associated drives).

[0066] Each of the pressure sensors 86, 86', 86” provides an input signal to the controller 90 indicative a detected pressure in the respective flow passage 78, 78', 64.

[0067] Electronic communications among the various components of the CTIS 12 and / or the tractor 9 may be achieved over a controller area network (CAN) bus or via a communications medium using other standard or proprietary communication protocols (e.g., RS 232, etc.). Communication may be achieved over a wired medium, wireless medium, or a combination of wired and wireless media.

[0068] The processor 90a may be embodied as a custom-made or commercially available processor, a central processing unit (CPU) or an auxiliary processor among several processors, a semiconductor based microprocessor (in the form of a microchip), a macro processor, one or more application specific integrated circuits (ASICs), a plurality of suitably configured digital logic gates, and / or other well-known electrical configurations comprising discrete elements both individually and in various combinations to coordinate the overall operation of the controller 90.

[0069] Use of separate valve modules 74, 76 to control the pressures in the centre section wheels 30a-30d and the wing wheels 30'a, 30'b makes it possible to monitor and adjust the tire pressures of the wing wheels independently of the centre section wheels and can, for example, allow the tires on the wing wheels to be inflated whilst deflating the tires on the centre section wheels or vice versa. The tires of the centre section wheels 30a, 30b, 30c, 30d can be considered a first group of tires and the tires of the wing wheels 30'a, 30'b can be considered a second group of tires.

[0070] As noted above, in the embodiment illustrated, each rotary coupling 56 may be provided as part of a unit or weighing cell including a sensor for measuring the load on the wheel and hence the weight supported by a tire on the wheel. The weight sensors 63 are indicated schematically in FIG. 3 at 63a to 63f. The weight sensors 63a to 63f each provide an input to the controller in the form of a signal indicative of the weight supported by their respective tire.

[0071] In addition to the weight sensors 63, other sensors may provide an input to the CTIS controller 90. These may include a speed sensor indicated schematically at 96 for generating a signal indicative of the speed of the implement across the ground. The speed sensor 96 can be any suitable sensor for providing a signal to the CTIS controller indicative of the speed of the planter across the ground. The speed sensor 96 may be provided on the planter itself but could alternatively be provided on the towing tractor.

[0072] In use when traversing a field, the controller of a conventional CTIS monitors weight data from the tire weight sensors 63 and ground speed data from the ground speed sensor 96 and issues control signals to the valves 80, 82, 84 in the main valve manifold 52 to adjust the tire pressures such that they are kept as low as possible without going below a minimum tire pressure required to avoid damaging the tires forthe weight supported and the ground speed. Data correlating required (e.g., recommended) minimum tire pressures, weight supported, and ground speed may be provided by a tire manufacture. Such data may be stored in a look up table or the like in a memory 90b to which the processor 90a has access. Alternatively, such data may be analysed to generate an equation or algorithm that relates required tire pressure to speed and weight. The equation or algorithm may be stored to memory 90b accessible to the controller processor such that the controller 90a can determine the required minimum tire pressure from the weight and speed data using the equation.

[0073] In an example, the highest weight supported by any of the tires and reported to the controller 90 is used to determine the required minimum tire pressure. Where the tires on the implement are assigned to different groups and where the pressure of tires in each group can be adjusted independently of the tires in the other group or groups, the pressure of the tires in each group will be adjusted based on the highest weight supported by any one of the tires in that group as reported by the tire weight sensors 63. For example, in the present example, the pressure in the tires 32 on the central section wheels 30a to 30d may be adjusted in dependence on the highest weight supported by any of the central section tires32 and the pressure in the tires 32 on the wing section wheels 30'a, 30'b may be adjusted in dependence on the highest weight supported by the wing section tires. In this case, a different required minimum tire pressure may be set for the centre section tires than for the wing tires.

[0074] The tire pressures are adjusted considering changes in the weight of the implement, for example due to consumables being deposited on the field or replenished and taking into account changes in speed.

[0075] In an example, the CTIS is configured to apply a field mode of use when the wing sections 22b, 22c are deployed in their working positions to extend transversely, generally in-line with the central section 22a and to apply a road mode of use when the wing sections 22b, 22c are folded to their transport position in which they extend generally in a longitudinal direction X of the planter. Suitable sensors may be used to provide signals indicative of the configuration of the wing sections or data may be provided from a control system used to move the wing sections between their working and transport positions. However, other suitable arrangements for causing the CITS to switch between a field mode of use and a road mode of use can be adopted. For example, particularly but not exclusively for a planter having only one toolbar section, a user input may be used to select either field or road mode of use, the speed of the vehicle could be used, indeed many other triggers indicative of field or road use can be adopted as will be clear to those skilled in the art.

[0076] The weight supported by the tires 32 changes depending on whether the row units 20 are lowered to engage the ground or raised clear of the ground. When the row units 20 are in the raised position, the weight supported by the tires is increased compared to when the row units 20 are in the lowered position, all other things remaining the same. The CTIS will take these changes into account to adjust the tire pressures. However, when the row units 20 are raised at the end of a run across the field to execute a headland turn, the conventional CTIS may not be able to increase the tire pressures sufficiently quickly to ensure they are kept at or above the recommended minimum required tire pressure for the weight supported and ground speed as the turn is executed. This may lead to tire damage.

[0077] To overcome this issue, a CTIS according to an example of the disclosure is configured to determine the minimum tire pressure required to avoid tire damage based on the weight supported by tires with the row units raised and to set this as a system minimum tire pressure, which may be stored to memory 90b. The controller 90 applies the system minimum tire pressure at least during subsequent use of the implement in the field.Determining the system minimum tire pressure may take into account both the weight supported by the tires 32 with the row units 20 raised and also the ground speed of the implement at the time the system minimum tire pressure is being set. In an example, a predefined ground speed is used to determine the system minimum tire pressure in the event that the implement is traveling at a speed below the pre-defined ground speed at the time the system minimum tire pressure is set. The pre-defined ground speed may be selected based on an expected speed at which the implement will undertake a headland turn or other similar manoeuvre. Use of a pre-defined ground speed should ensure that the system minimum tire pressure is set at a level that is sufficient to support the weight of the implement with the row units raised during a headland turn or similar manoeuvre without damaging the tires. In a non-limiting example, a pre-defined ground speed in the range of 10 to 16 kph may be used.

[0078] During subsequent use of the implement in a field, the CTIS will operate to monitor tire pressures, the weight supported by the tires, and ground speed and to adjust the tire pressures so that they are kept as low as possible without falling below a higher of the currently set system minimum tire pressure and the required minimum tire pressure for the current weight and speed. When the row units 20 are lowered, it is expected that the tire pressures will be maintained at the system minimum tire pressure, but they may be raised above this if the speed and / or other conditions (e.g., soft ground) require a higher tire pressure to avoid tire damage. With this system, the pressure in the tires will always be set at a pressure that is suitable for performing a headland turn with the row units 20 raised and so avoids the problem that the CTIS is unable to raise the tire pressures quickly enough when the row units 20 are raised to perform a headland turn. It will be appreciated that the tire pressures may also be raised above the system minimum tire pressure during a headland turn or at other times when the row units 20 are raised if the conditions (e.g., weight supported by the tires and ground speed) require a higher tire pressure to avoid tire damage according to the manufacturer's recommendations.

[0079] In an example, the highest weight supported by any of the tires and reported to the controller 90 with the row units 20 raised is used to determine the system minimum tire pressure. Where the tires on the implement are assigned to different groups and where the pressure of tires in each group can be adjusted independently of the tires in the other group or groups, a respective system minimum tire pressure can be determined and set foreach group of tires based on the highest weight supported by any one of the tires in that group as reported by the tire weight sensors 63 with the row units 20 raised. For example, in the present example, a first system minimum tire pressure may be determined and set for the tires 32 on the central section wheels 30a to 30d in dependence on the highest weight supported by any of the central section tires 32 and a second system minimum tire pressure, which may be different from the first, may be determined and set for the tires 32 on the wing section wheels 30'a, 30'b in dependence on the highest weight supported by the wing section tires.

[0080] The system minimum tire pressure may be updated periodically when the row units 20 are raised. In an example, the system minimum tire pressure is updated each time the row units are raised. This allows the system minimum tire pressure to be adjusted to take into account changes in the overall weight of the implement (say as consumables are dispensed on the field or replenished) and changes in the speed the implement is moving with the row units raised.

[0081] The system may be configured such that the system minimum tire pressure can only be changed by a limited amount each time it is reset to prevent excessive variations in the system minimum tire pressures that might arise in the event of an anomalous detection of the weight supported by the tires or some other fault in the system. In an example, the system is configured such that any change in the system minimum tire pressure is limited to a predetermined percentage of the currently set system minimum tire pressure. Alternatively, the permitted change may be limited to a percentage change of an average of the currently set system minimum tire pressure and a predetermined number of the immediately previously set system minimum tire pressures. In either case, a suitable percentage may be in the region of 5% to 10%, for example. However, a change in the system minimum tire pressure above the usual limit might be permitted in certain circumstances, such as for the first time the system minimum tire pressure is reset after consumables, such as seed and / or fertilizer, have been introduced on to the implement. In this case, the controller 90 may be operative in response to an input indicative that consumables have been added to allow a larger than normal change to the system minimum tire pressure. A suitable input may be a user input provided through a user interface or an input from one or more sensors, for example.

[0082] To determine whetherthe row units 20 are raised or lowered, the implement 12 may have at least one row unit position sensor, indicated schematically at 98. The at least one row unit position sensor can be any suitable sensor for providing a signal to the CTIS controller 90 indicative that one or more of the row units are in the raised position. A respective row unit position sensor 98 may be provided for each row unit 20. Alternatively, a single row unit position sensor 98 may be provided for a group of row units, especially where they are configured to be moved between lowered and raised positions simultaneously. For example, a single row unit position sensor 98 may be associated with the row units mounted to the secondary 26 of each of the central and wing sections. In a still further example, a single row unit position sensor 98 may be provided for all the row units. In one example, the, or each, row unit position sensor 98 may be a proximity sensor capable of detecting when a row unit, a part thereof, or a part of the frame of the implement to which the row units are mounted is in a position adopted when the row units 20 are in their raised position. In an alternative example, the, or each, row unit position sensor 98 may be a load sensor for sensing a load on a row unit, a part thereof, or on a part of the frame of the implement to which the row units are mounted, where the sensed load changes depending on whetherthe row unit(s) is / are in a lowered position in contact with the ground or a raised position clear of the ground. In a further example, the, or each, row unit position sensor 98 may be associated with an actuation system used to move the row units 20 between their lowered and raised positions. In the example shown in FIG. 1, hydraulic actuators in the form of hydraulic cylinders 100 are operative between the main tool bar 24 and the seed tool bar 26 of each of the central and wing sections to move the seed tool bar 26 relative to the main tool bar 24 and so raise and lower the row units 20 mounted to the seed tool bar. In this type of arrangement, the, or each, row unit position sensor 98 may be configured to detect a characteristic of an actuator 100 indicative that the row units 20 are in the raised position. In a still further example, a row unit position sensor 98 could take the form of a camera or device for capturing images of the implement, and especially the row units, from which the raised or lowered position of the row units 20 can be determined.

[0083] It should also be noted that an input to the CTIS control 90 indicative that the row units 20 are raised need not come from a sensor but may come from a control system on the implement or the towing tractor which is operative to control movement of the row units between their raised and lowered positions. In an example, the CTIS may be configuredto determine that the row units 26 are raised based on receipt of a signal from such a control system that raising of the row units from the lowered position has been initiated. A suitable time-delay could be applied after a signal to raise the row units as been provided to the actuation system to allow time for them to reach a raised position before the control unit determines the weight acting on the tires for setting of a system minimum tire pressure in accordance with the present disclosure.

[0084] When the CTIS is operating in a road mode, the tire pressures are generally kept towards a higher end limit of the recommended tire pressures for the speed and weight supported by the tires. This would usually be well above the system minimum tire pressure and so a system minimum tire pressure may not be set, or if one is still set may not be applied. A new system minimum tire pressure may be set each time the implement is placed in a suitable configuration for use in a field and the CTIS operated in a field mode of use. For example, where the toolbar has multiple sections that unfold from the transport position to the field use position, a system minim tire pressure could be set after the toolbar is unfolded with the row units raised or some other input provided to indicate that the planter is about to be used in a field.

[0085] FIG. 4 illustrates schematically a tractor 9 towing a planter 12 having a CITIS as described above with reference to FIGs. 1 to 3. The tractor 9 is towing the planter 12 across a field in the direction of arrow F. In the embodiment illustrated, the tractor has a controller 200 having one or more processors, such as processor 200a, input / output (I / O) interface(s), and memory 200b, all coupled to one or more data busses. The tractor may also have a HMI 92 which may be a touch screen, or it may be a combination of a display system and other user input devices, or just a display screen. In an embodiment, the HMI is part of the control system of the tractor and the CTIS controller 90 on the planter 12 is in communication with the controller 200 and HMI 92 on the tractor so that data relating to the CTIS can be displayed to the driver. The driver may also be able to input data or instructions for the CTIS. In other embodiments, the CTIS controller 90 could be provided on the tractor or divided across the planter and tractor. In another embodiment, the HMI 92 does not form part of the tractor control system and the CTIS controller 90 communicates with the HMI 92 without going through the tractor controller 200. Electronic communication between components on the tractor 9 and those on the planter 12 may be over a controller area network (CAN) bus or via a communications medium using other standard or proprietary communication protocols(e.g., RS 232, etc.). Communication may be achieved over a wired medium, wireless medium, or a combination of wired and wireless media.

[0086] Electrical power for the CTIS on the planter 12 may be provided from the tractor 9.

[0087] Various modifications can be made to embodiments described as will be clear to those skilled in the art. For example, alternative valve arrangements can be adopted to enable any one or more tires to be selectively connected to a source of pressurised air 50 to be inflated or to an exhaust outlet 94 to be deflated.

Claims

CLAIMSWhat is claimed is:

1. An implement for working an agricultural field, the implement comprising a frame supported on the ground by a plurality of tires and a plurality of row units carried by the frame, the row units configured for movement between a lowered position in which they are brought into contact with the ground and a raised position in which they are lifted clear of the ground, and at least one weight sensor for generating a signal indicative of the weight supported by at least one the tires, the implement having a central tire inflation system for monitoring and adjusting the air pressure of the tires, the central tire inflation system including at least one processor and at least one non-transitory computer-readable storage medium storing instructions thereon that, when executed by the at least one processor, cause the central tire inflation system to receive weight data indicative of the weight supported by the at least one the tires from the at least one weight sensor when the row units are in the raised position and to set a system minimum tire pressure based at least in part on the received weight data and to subsequently monitor and adjust the pressure of the air in the tires without allowing the tire pressures to fall below the currently set system minimum tire pressure.

2. The implement of claim 1, wherein the implement further includes instructions that, when executed by the at least one processor, cause the central tire inflation system to receive row unit position data indicative that the row units are in a raised position and to initiate setting of the system minimum tire pressured on receipt of the row unit position data.

3. The implement of claim 1 or claim 2, wherein the implement further includes instructions that, when executed by the at least one processor, cause the central tire inflation system to receive data indicative of the ground speed of the implement and to set the system minimum tire pressure based at least in part both on the weight data and the speed data and wherein, optionally, the implement further includes instructions that, when executed by the at least one processor, cause the central tire inflation system to set the system minimum tire pressure based at least in part on the weight data and a predefined minimum speed in the event the speed data indicatesthat the implement is travelling at or below the predefined minimum speed when setting the system minimum tire pressure.

4. The implement of any one of claims 1 to 3, wherein the implement has more than one weight sensor, each weight sensor for detecting a weight indicative of the weight supported by an associated one of the tires, and the implement further includes instructions that, when executed by the at least one processor, cause the central tire inflation system to set the system minimum tire pressure based at least in part on weight data received from the weight sensors that is indicative of a highest weight supported by any one of the associated tires.

5. The implement of any one of claims 1 to 4, wherein the tires are assigned to at least two distinct groups and the implement further includes instructions that, when executed by the at least one processor, causes the central tire inflation system to set a respective system minimum tire pressure for each group based at least in part on weight data received from a respective weight sensor associated with at least one tire in that group.

6. The implement of any one of claims 1 to 5, wherein the implement further includes instructions that, when executed by the at least one processor, cause the central tire inflation system to update the set system minimum tire pressure periodically when the row units are raised and wherein, optionally, the instructions, when executed by the at least one processor, cause the central tire inflation system to update the stored system minimum tire pressure each time the row units are raised.

7. The implement of claim 6, wherein the implement further includes instructions that, when executed by the at least one processor, cause the central tire inflation system when updating the system minimum tire pressure to apply a predefined limit to the amount by which the system minimum tire pressure is changed each time it is updated.

8. The implement of claim 7, wherein the predefined limit is a percentage of one of: a. the currently set minimum tire pressure; and b. an average of the currently stored system minimum tire pressure and a predetermined number of previously stored system minimum tire pressures.

9. The implement of any one of claims 1 to 8, wherein the implement further comprises instructions that, when executed by the at least one processor, cause the central tireinflation system when subsequently monitoring and adjusting the pressure of the air in the tires as the implement traverses a field to not allow the tire pressure to fall below a minimum tire pressure required to prevent tire damage for the weight supported and implement ground speed.

10. A combination of an implement according to any one of claims 1 to 9 and a towing vehicle.

11. The combination of claim 10, wherein the at least one processor is in communication with a HMI and / or a speed sensor located on the towing vehicle.

12. A computer implemented method of automatically adjusting the tire pressures of an implement for working an agricultural field, the implement comprising a frame supported on the ground by a plurality of tires and a plurality of row units carried by the frame, the row units configured for movement between a lowered position in which they are brought into contact with the ground and a raised position in which they are lifted clear of the ground, the method comprising receiving weight data indicative of the weight supported by at least one of the tires when the row units are in the raised position from a weight sensor system and setting a system minimum pressure based at least in part on the received weight data, the method further comprising subsequently monitoring and controlling the tire pressures when the implement is traversing a field without allowing the pressure in the tires to fall below a currently set system minimum tire pressure.

13. The method of claim 12, wherein the method comprises setting the system minimum tire pressure based at least in part both on the weight supported by the tires and the speed of the implement across the ground, and wherein, optionally, the method comprises setting the system minimum tire pressure based at least in part on the weight supported by the tires and a predefined minimum speed in the event the implement is travelling at or below the predefined minimum speed at the time the system minimum tire pressure is being set.

14. The method of claim 12 or claim 13, wherein the method comprises updating the system minimum tire pressure periodically when the row units are raised and, optionally, updating the system minimum tire pressure each time the row units are raised.

15. The method of claim 14, wherein the method comprises apply a predefined limit to the amount by which the system minimum tire pressure is changed each time it is updated.

16. The method of claim 15, wherein the predefined limit is a percentage of one of: a. the currently set minimum tire pressure; and b. an average of the currently stored system minimum tire pressure and a predetermined number of previously stored system minimum tire pressures.

17. The method of claim 15 or claim 16, wherein the method comprises permitting a change in the system minimum tire pressure which exceeds the predefined limit depending on the operational status of the implement.

18. The method of any one of claims 12 to 17, wherein the method comprises assigning the tires to least two groups of tires and setting a respective system minimum tire pressure for each group.

19. The method of claim one of claims 12 to 18, wherein subsequently monitoring and controlling the tire pressures without allowing the pressure in any of the tires to fall below the currently set system minimum tire pressure comprises monitoring and adjusting the tire pressures as the implement traverses a field dependent at least in part on the weight supported by the tires and the speed of the implement over the ground to maintain the tire pressures as low as possible without falling below a highest of the currently set system minimum tire pressure and a minimum tire pressure required to prevent damage to the tires for the weight supported and implement ground speed.

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