Background of the Invention

The invention refers to an open-loop and/or closed-loop control system for an agricultural utility vehicle according to the preamble of patent claim1. Furthermore, the invention refers to an agricultural utility vehicle according to claim16, as well as a method for controlling an agricultural utility vehicle according to claim17.

Such systems are used for agricultural vehicles for the application of materials such as fertilisers, plant protection agents or seeds. In order to spread the material efficiently and over a large area on the field soil to be worked, the agricultural utility vehicles have a distributor linkage with several spray nozzles. The distributor linkage extends transversely to the direction of travel and can have working widths of up to 40 m. The spray nozzles, which are mounted at regular intervals on the distributor linkage, are used for spreading the material on the ground to be worked. The distance between the distributor linkage and the ground should remain as constant as possible over the entire working width of the distributor linkage. This means that the distributor linkage is kept as parallel as possible to the ground to be worked.

As is well known, the distributor linkage has a centre part, for example a centrally located frame, and two lateral extension arms connected to the centre part, with several linkage sections, connected by joints, which can be folded in to one another in the transport position and folded out to the working position. The individual linkage sections can be pivoted about vertical axes via the corresponding joints and are mounted so that they can rotate about the respective vertical axis. By means of the fold-out linkage sections, the distributor linkage can thus be transferred from a space-saving transport position to a working position. The transport position describes the folded state of the distributor linkage. In contrast, the working position describes the condition of the distributor linkage in which all linkage sections are folded out. In other words, in the working position the distributor linkage has the entire working width and is in a completely horizontal starting position parallel to the ground.

When operating an agricultural utility vehicle with such a large working width, vibrations of the distributor linkage in or opposite to the direction of travel can occur, for example, due to driving over uneven ground, acceleration or braking of the utility vehicle. Due to such vibrations, very high forces can occur on the distributor linkage and homogeneous material output can no longer be guaranteed. It is therefore known, as an example from EP 2 829 177 B1, to arrange actuating and/or damping means between the centre part and the extension arm or between the linkage sections in such a way that on the one hand the distributor linkage can be transferred from a transport position into a working position and on the other hand damping of vibrations occurring on the distributor linkage can take place in the direction of travel. The positioning and/or damping means can be designed as hydraulically operating cylinders. As a result of vibrations of the distributor linkage, pressure differences arise in the hydraulic cylinders.

To control the damping of the vibrations, the positioning and/or damping means can therefore be controlled by a data processing unit. For this purpose, the data processing unit evaluates the signals from a plurality of sensors arranged on the distributor linkage for position and speed monitoring of the agricultural utility vehicle in order to generate a control signal for the hydraulic cylinders. The sensors, such as radar sensors or pulse generators, are used to determine the current type of movement of the agricultural utility vehicle, i.e. whether the utility vehicle is moving at a continuous speed or whether the utility vehicle is being accelerated or decelerated. The position of the distributor linkage can be monitored by means of an angle sensor.

For efficient material application and to avoid high mechanical loads on the distributor linkage, it is generally necessary to dampen vibrations as quickly as possible and independent of the type of movement of the agricultural utility vehicle. It is particularly desirable if the damping of the vibrations can be variably adjusted.

Summary of the Invention

The invention is therefore based on the object of providing a an open-loop and/or closed-loop control system for an agricultural utility vehicle, in which precise and variably adjustable damping of occurring vibrations in or opposite to the direction of travel can take place. The invention is also based on the object of providing an agricultural utility vehicle and a method for the open-loop and/or closed loop control of an agricultural utility vehicle.

This object is solved according to the invention by an open-loop and/or closed-loop control system comprising the features of claim1. With regard to the agricultural utility vehicle, the object is solved by the subject matter of claim16. Furthermore, with regard to the method, the object is solved by the subject matter of claim17.

The invention is based on the idea of providing an open-loop and/or closed-loop control system for an agricultural utility vehicle, with a distributor linkage for applying material such as fertiliser, plant protection agent or seeds, which extends transversely to the direction of travel and has a centre part and two lateral extension arms connected to the centre part, with a plurality of linkage sections connected by joints which can be folded in to one another in the transport position and folded out to the working position. At least one hydraulic device is associated with each extension arm, whereby the distributor linkage can be transferred from a transport position to a working position. The system further comprises at least one sensor and a data processing unit which is configured such that the signals of the at least one sensor are processed and on the basis of which a control signal for the hydraulic device is generated, and the hydraulic device is controllable for adjusting the damping of vibrations occurring on the distributor linkage in the direction of travel. The sensor is designed in such a way that a pressure change occurring at the hydraulic device due to vibrations of the distributor linkage can be determined.

The invention has the advantage that the data processing unit can be used to variably adjust and/or re-adjust the damping of the vibrations occurring on the distributor linkage. This means that stronger damping can occur with strong vibrations of the distributor linkage and correspondingly lower damping with low vibrations of the distributor linkage. Here it is of particular advantage that the pressure change at the hydraulic device can be determined by means of the sensor. Since the pressure change that occurs is known, the data processing unit can adjust the damping immediately and directly to the pressure change that occurs. The damping of vibrations is therefore adjusted precisely and as quickly as possible, irrespective of the current operating status of the utility vehicle. Therefore, it is not necessary to draw conclusions about the occurring pressure change from other measurement data of otherwise designed sensors, or to calculate the pressure change from other measurement data, but the pressure change can be determined directly. As a result, the vibrations that occur can be efficiently counteracted. Due to the direct determination of the pressure change at the hydraulic device, interference effects or superimpositions of measurement errors, which can have a negative effect on the measurement signals of other sensors, are already compensated.

The data processing unit preferably has a control and/or evaluation program which processes and evaluates the signals of at least one sensor as an input variable and, based on this, can generate a control signal for the respective hydraulic device.

Preferred embodiments of the invention are indicated in the subclaims.

In a preferred embodiment of the invention, the sensor is designed in such a way that a pressure difference can be measured at the hydraulic device. Accordingly, the pressure change occurring can be measured directly and immediately by means of the sensor. This means that the data processing unit receives a directly measured value for the pressure difference as the input variable for setting the damping. The advantage of measuring the pressure difference is that an exact value of the pressure change occurring on the hydraulic device is already known, and therefore the data processing unit can adapt, adjust and/or re-adjust the damping to the pressure difference measured by the sensor as quickly and precisely as possible.

Furthermore, the sensor is preferably designed as a pressure sensor for direct pressure measurement, in particular as a pressure transducer. The design of the sensor as a pressure sensor has the advantage that both a relative pressure and an absolute pressure can be determined. Furthermore, the sensor can preferably be designed as a differential pressure transducer for determining a differential pressure or an occurring pressure difference. The design of the sensor as a pressure transducer is particularly suitable for the use of hydraulic devices. Advantageously, the pressure transducer can record the pressure to be measured via a measuring diaphragm, which is converted mechanically depending on the respective pressure. This mechanical change is measured electronically and output as an analogue output signal and transmitted to the data processing unit. Preferably two sensors are assigned to a hydraulic device. This can also be used to determine a differential pressure. This has the advantage that pressure differences can be determined as precisely as possible.

Alternatively, it is also conceivable to draw indirect conclusions about an occurring pressure change in comparison to direct pressure measurement at the hydraulic device by means of a pressure sensor. The position or angle of the linkage sections can for instance be measured by a potentiometer. The potentiometer determines whether a single linkage section or the entire extension arm is deflected from its horizontal position due to a vibration and how its position changes. In principle, this can also be used to infer a change in pressure due to the deflection. However, the direct determination of the pressure change or the measurement of the pressure difference has the advantage that a robust and solid measured value and thus a reliable input variable without interference effects can be provided for the data processing unit.

Particularly preferably, the hydraulic device comprises a hydraulic cylinder, in particular a double-acting hydraulic cylinder, a hydraulic line which is connected to the hydraulic cylinder for supplying hydraulic fluid, and at least one hydraulic valve unit for regulating the hydraulic pressure, the valve unit being controllable via an actuating signal of the data processing unit. In general, the use of a hydraulic fluid has the advantage that the friction within the hydraulic device is reduced and corrosion protection can be guaranteed at the same time. The hydraulic device can generally be designed as an actuator in order to convert the electrical control signals of the data processing unit into a mechanical movement and thus to transfer the distributor linkage from a transport position to a working position as well as to ensure the damping of vibrations occurring on the distributor linkage in the direction of travel. The hydraulic valve unit advantageously provides a safe and fast acting overload protection of the hydraulic cylinder. Overall, the hydraulic pressure on the hydraulic cylinder can be optimally adjusted using the hydraulic valve unit, which can be controlled by the data processing unit using a control signal.

In another preferred embodiment, the at least one hydraulic valve unit is formed by a proportional valve, in particular a 4-way valve. The hydraulic valve unit can, for example, also include a pressure control valve or other circuits for changing the hydraulic pressure in the hydraulic device.

Preferably, the respective hydraulic valve unit can be adjusted based on a measured signal from the sensor or an actual value determined otherwise. It is generally conceivable that, in addition to the at least one sensor to determine a pressure change occurring on the hydraulic device, further sensors are used in order to determine the position of an individual linkage section or of the extension arm of the distributor linkage and to indirectly conclude that a pressure change is occurring. The determination of the occurring pressure change at the hydraulic device allows a precise adjustment of the damping of occurring vibrations. The pressure change can be measured directly by means of the sensor, or otherwise and indirectly determined by other sensors.

In another preferred embodiment, further sensors are arranged on the distributor linkage to detect rotation about a hinged axis and/or position detection of the respective linkage section and/or extension arm. These sensors can advantageously be designed as potentiometers and determine the position of the distributor linkage and/or the individual linkage sections. The potentiometer determines whether a single linkage section or the entire extension arm is deflected from its horizontal position due to a vibration and how its position changes. The hinged axis, around which the extension arm folding is carried out, is preferably vertically oriented but has at least one vertical component. The position determination can, for example, be implemented by measuring the deflection of the hydraulic cylinder.

In a further embodiment, the hydraulic device is adjustable based on a measured signal of the sensor with respect to a pressure change occurring at the hydraulic device and taking into account a pressure offset occurring due to a pitch inclination of the agricultural utility vehicle and/or based on the measured signals of the sensors with respect to a rotation occurring about a hinged axis and/or position detection of the respective linkage section and/or extension arm. As an example, the measured signal of the sensor can be evaluated by the data processing unit with regard to a pressure change occurring at the hydraulic device, taking into account a pressure offset. An external force acting on the distributor linkage can be taken into account by considering a pressure offset. Such forces can occur, for example, in the case of pitch inclinations of the agricultural utility vehicle in or in the opposite direction to the direction of travel. Thus the hydraulic valve unit can be adjusted by the data processing unit based on a combination of the pressure offset and the measurement of the pressure change occurring. Alternatively or additionally the rotation of the hinged axis of the respective linkage section and/or extension arm can, for example, be determined by means of a potentiometer. The data processing unit can carry out a target/actual value comparison with regard to the hinged axis and, based on the control difference and in combination with the pressure offset and the measurement of the pressure change occurring at the hydraulic device, set the hydraulic valve unit. The combination of different measured values in the data processing unit allows a very precise adjustment of the hydraulic valve unit. Any measurement inaccuracies that may occur can also be compensated.

In total, the data processing unit can control or adjust the associated hydraulic valve unit of the hydraulic device for damping vibrations occurring on the distributor linkage based on the measured signal of the sensor or the current position of the linkage section or extension arm. It is generally conceivable to use the measured signals of the sensor also in a control system as target value and for the adaptation of a target value. The data processing unit can be configured, or in other words have such a control and/or evaluation program, that, based on the measured signal of the at least one sensor, a corresponding target value for the respective hydraulic device is determined as an input value for the control, and the hydraulic device is controlled or set to the target value in such a way.

The hydraulic valve unit can also preferably be electronically controlled using a known characteristic curve. The characteristic curve of the valve unit generally reflects the functional dependence of the output signal on the input signal. Ideally the output signal will change linear with the occurring pressure as input signal. The ideal characteristic curve would therefore be a straight line. The measured, or in other words the real characteristic curve of the hydraulic valve unit cannot be exactly linear, but even at the start and end point of the pressure range the output signals deviate from the respective ideal values. It is therefore of particular advantage for a precise adjustment of the damping of vibrations occurring on the distributor linkage to adjust the hydraulic valve unit on the basis of its characteristic curve and therefore to adapt to and counteract the pressure change that occurs. Using the pressure sensors as an example, the characteristic curve of the valve unit can be used to determine how large the required control current must be switched to the valve unit in order to counteract the pressure change that occurs.

In a further embodiment, the at least one hydraulic valve unit of the respective hydraulic device can be adjusted and/or re-adjusted independently of the data processing unit. This means that the hydraulic valve unit of the associated hydraulic device of the respective extension arm can be controlled independently of each other via an electronic signal from the data processing unit. Therefore, the open-loop and/or closed-loop control system can be used efficiently for both symmetrical and asymmetrical distributor linkages. It is advantageous that the hydraulic line connected to the respective hydraulic cylinder is connected to at least one hydraulic accumulator. It is conceivable that the open-loop and/or closed-loop control system comprises a central hydraulic accumulator or, alternatively, one hydraulic accumulator each is assigned to the right-hand or left-hand extension arm of the distributor linkage. The hydraulic accumulator advantageously generates the hydraulic pressure acting in the hydraulic cylinder.

Furthermore, two pressure sensors in the hydraulic line are preferably assigned to the respective hydraulic cylinder in such a way that both the applied pressure on a piston surface and on an annular surface of the hydraulic cylinder can be determined. Thus a precise pressure measurement at the hydraulic cylinder, or in other words a precise determination of the pressure difference occurring at the hydraulic cylinder due to vibrations of the distributor linkage can be made.

In another embodiment, the hydraulic devices assigned to the respective extension arm form a closed hydraulic circuit, whereby the hydraulic cylinders of the hydraulic devices are connected by a common hydraulic line. Ideally, this means that there is no need to attach individual separate hydraulic lines and the sensors for determining any pressure changes that occur on the hydraulic equipment can also be attached to the common hydraulic line.

Advantageously, a pressure sensor is arranged in the common hydraulic line in such a way that the pressure on the annular surface of all hydraulic cylinders can be determined. In this case the pressure on the annular surfaces of the hydraulic cylinders is at least approximately identical.

In a preferred embodiment, the data processing unit forms a unit with the at least one sensor and the at least one hydraulic device. This implies a direct connection, for example via cable lines or wirelessly, between the sensor and the data processing unit, as well as the hydraulic equipment. Therefore, the measuring signal acquired by the sensor can be transmitted efficiently and as quickly as possible to the hydraulic vibration damping device via a control signal of the data processing unit.

In the context of this application, an agricultural utility vehicle is also claimed for the application of material such as fertilisers, plant protection agents or seeds with a open-loop and/or closed-loop control system according to one of the preceding embodiments.

Furthermore, a method for the open-loop and/or closed loop control of an agricultural utility vehicle is disclosed within the scope of the present application, having a distributor linkage for dispensing material, such as fertiliser, plant protection agents or seeds, which extends transversely to the direction of travel and has a centre part and two lateral extension arms connected to the centre part and having a plurality of linkage sections connected by joints which can be folded in relative to one another in the transport position and folded out in the working position. At least one hydraulic device is associated with each extension arm, whereby the distributor linkage can be transferred from a transport position to a working position. The system further comprises a sensor and a data processing unit which is configured such that the signals of the at least one sensor are processed and on the basis of which a control signal for a hydraulic device is generated, and the hydraulic device is controlled for adjusting the damping of vibrations occurring on the distributor linkage in the direction of travel. The sensor detects a pressure change at the hydraulic device caused by vibrations of the distributor linkage. In particular, the sensor, in particular the differential pressure transducer, measures a pressure difference at the hydraulic device. Alternatively, the pressure difference at the hydraulic device can be determined by a plurality of sensors.

Furthermore, preferably based on a measured signal of the sensor or an otherwise determined actual value, the at least one hydraulic device is adjusted and/or adjusted by means of the data processing unit.

It is advantageous that the respective hydraulic devices of the extension arms are adjusted and/or re-adjusted independently of each other.

With regard to the advantages of the method for controlling an agricultural utility vehicle, reference is made to the advantages explained in connection with the open-loop and/or closed-loop control system.

