METHOD

1 . FIELD OF THE INVENTION

The invention refers to a hydraulic system of an agricultural machine. The hydraulic system comprises an assembly for detecting a fluid connection between a fluid source and at least one machine part. In the case of an established fluid connection the machine part is supplied with a hydraulic fluid conveyed out of the fluid source. In particular the hydraulic system supplies a part of an agricultural implement with fluid wherein the implement is pulled by a tractor and the tractor comprises the fluid source which provides the fluid. The agricultural implement can be a haymaking machine, a baler, a self-loading wagon, a mower or a soil cultivating machine and can be connected or hitched to a tractor, e.g. The invention further refers to a method for automatically detecting such a fluid connection.

2. BACKGROUND OF THE INVENTION

In the field of agriculture many different types of machines are available for different types of work that must be done on the field. Many agricultural machines such as haymaking machines, balers, self-loading wagons, mowers, seeding machines, or soil cultivating machines need to be pulled over the field and for that reason they can be connected or hitched to a pulling vehicle such as a tractor. In this application the agricultural machine operates as an implement.

All such agricultural implements comprise working elements or moveable machine parts. At least some of those working elements or machine parts are powered by hydraulic energy or hydraulic motors. The hydraulic power source is often not mounted on board of the implement itself. In this case the agricultural implement has to be connected to the hydraulic system of the pulling vehicle which provides a source of hydraulic energy and/or working fluid and a fluid pump.

In order to connect an agricultural implement to the hydraulic system of a tractor or further pulling vehicle, the pulling vehicle is typically provided with a plurality of hydraulic pressure supply connecting devices to which hydraulic pressure lines, provided with suitable connectors (end pieces), of the agricultural implement can be connected. Before starting operation a human operator connects the connectors with the pressure supply connecting devices. Once these hydraulic lines are connected to the hydraulic pressure supply connecting devices of the pulling vehicle, the agricultural implement can be operated. The operator works in a driver's cabin of the pulling vehicle and triggers agricultural functions during operation.

US 201 10315234 A1 discloses an agricultural combination with a tractor 90 and an implement 10, cf. Fig. 1. For steering the implement 10, two actuating cylinders 38 and 40 can steer the two left wheels and the two right wheels 26 of the implement 10, resp., cf. Fig. 3. Therefore the implement 10 can selectively move in a curve to the right or to the left. Fig. 10 shows a hydraulic system for supplying the actuating cylinders 38 and 40 with hydraulic fluid. A hydraulic supply 96 mounted on board of the tractor 90 is connected with the implement by means of a first hydraulic conduit 98 and a second hydraulic conduit 100. Pressurized fluid is either supplied to the first conduit 98 or to the second conduit 100. The other conduit 100 or 98 serves as a return conduit to convey fluid back to the hydraulic supply 96. A controller 142 controls two selection control valves 102 and 100. The first selection control valve 102 selectively enables a flow between the first conduit 98 and the cylinders 38 and 40 in both directions or blocks a flow from the supply 96 to the cylinders 38 and 40. The second selection control valve 1 10 operates similarly for the second conduit 100. A first pressure sensor 138 measures the fluid pressure in the first conduit 98. A second pressure sensor 140 measures the fluid pressure in the second conduit 100. The controller 142 can thereby automatically determine which conduit 98 or 100 is supplied with pressure by selecting the conduit with the higher pressure. This information as well as the measured angle of the implement wheels 26 enables the controller 142 to automatically adjust the implement wheels 26 in a selected position. In addition the controller 142 can generate an alert to the operator if the fluid pressure within one conduit 98 or 100 is not sufficient for facilitate the desired or required rotation of the implement wheels 26.

In many applications the vehicle controller is pre-programmed in that a certain control action, for example by means of a computer on board of the pulling vehicle or by means of a manually operated lever, pressurizes or de- pressurizes a specific tractor-mounted connecting device. However, performing this operation does require that the proper implement part is supplied with fluid. To do so the correct connecting device of the pulling vehicle must supply fluid to this implement part. This means that in case that an incorrect connection has been made, the agricultural implement will not work at all or will not properly operate.

The desired function can only be performed or stopped if the pressurized or de-pressurized tractor-mounted connecting device is in fact connected to an implement part which performs a function or stops performing the function. Otherwise a malfunction may occur.

A simple solution would be that every hydraulic line of the implement can only be connected with exactly one tractor-mounted connecting device. But this solution would require a lot of different connecting devices and hydraulic line end pieces and would increase the costs for manufacturing and for supplying spare parts. Therefore it is desired to use standardized connecting devices and end pieces. A consequence is that one end piece can be connected with several connecting devices.

A known solution to assist the operator of the agricultural implement in connecting the implement to the tractor is as follows: The control unit uses a desired connecting scheme which assigns every hydraulic line to exactly one connecting device. The operator is assisted in connecting the hydraulic lines with the connecting devise according to this connecting scheme by providing the hydraulic connecting devices of the pulling vehicle and the hydraulic lines of the implement with two corresponding color coding systems. Every coding system comprises colored labels and/or colored lines. In this manner the operator is guided by the colored labels or lines to make sure that the hydraulic lines of the implement are in fact attached or connected to the intended connecting devices providing hydraulic pressure, i.e. that the given connecting scheme is properly considered.

A different solution which avoids the need of color coding is described in EP 2018981 B1 . According to this solution several hydraulic lines of the agricultural implement are provided with individual (RFID) transponders that can be connected to a respective mating connection for the supply of hydraulic energy on the tractor. The presence of a connection between a hydraulic line on the implement and a connection device on the tractor is detected by means of a so-called connection position detection apparatus implemented as an RFID reader. This RFID reader can read out the data stored in the transponders. The detection apparatus can supply the read out data to a controller on board of the tractor and by doing so provides said controller with the connection position information. After having received such information, the controller of the tractor can control the agricultural machine on the basis of the connection position information provided by the position detection apparatus.

3. SUMMARY OF THE INVENTION

A problem solved by the invention is to provide a hydraulic system with the features of the preamble of claim 1 and a fluid connection detecting method with the features of the preamble of claim 14 wherein a coding system with different colors or patterns needs not to be used and wherein the control unit can automatically identify that connecting device which is currently connected with the hydraulic line without the need of using several RFID chips or a further identification device which is necessarily subjected to dirt or rain.

This problem is solved by a hydraulic system with the features of claim 1 and by a fluid connection detecting method with the features of claim 14. Preferred embodiments are specified in the depending claims.

The hydraulic system according to the invention is for use on board of an agricultural machine and comprises

- at least one source for hydraulic fluid,

- a plurality of connecting devices,

- at least one hydraulic line,

- a control unit, and

- a detection device.

In the following the term "fluid" covers every kind of liquid or gas which can be conveyed from a source via at least one line to a fluid consumer on board of the agricultural machine. The term "fluid connection" denotes every kind of an assembly than can guide a fluid from a starting point to a target point.

A fluid connection between every connecting device and the or with one fluid source can be established. The or every hydraulic line is connectable with all or with some connecting devices or with at least one connecting device - one hydraulic line with one connecting device per time. On the other hand every connecting device of the plurality can be connected with the or with at least one hydraulic line. According to an intended use the hydraulic line can be disconnected from the connecting device. Actually connecting the or one hydraulic line with a connecting device and establishing a fluid connection between this connecting device and the or one fluid source establishes a fluid connection between this fluid source and this hydraulic line. A proper fluid connection between the hydraulic line and the fluid source can alternatively be established via several connecting devices.

The detection device can automatically detect whether or not at least one hydraulic line is supplied with fluid. If fluid supply is detected, the detection device generates a fluid supply detection signal. The control unit can receive and evaluate signals from the detection device. By evaluating received signals the control unit can automatically identify that or every connecting device of the plurality which is in fact connected with the or with one hydraulic line.

The connecting device which is in fact connected is automatically identified as follows:

- The control unit selects every connecting device of the plurality - one device after the other.

- The control unit establishes a fluid connection between the or one fluid source and the selected connecting device. Only this selected connecting device is currently in fluid connection with the or one fluid source. The other connecting devices are currently not in fluid connection while the detection step for the selected connecting device is performed. By this step a fluid connection between the fluid source and the hydraulic line via the selected connecting device is established - provided the hydraulic line is in fact connected with the currently selected connecting device.

- The detection device detects whether or not the or at least one hydraulic line is currently supplied with fluid.

- In the case that fluid supply is detected in this hydraulic line, the detection device generates a fluid supply detection signal.

- The control unit receives and evaluates signals from the detection device and detects what connection device is selected by the control unit when the fluid supply detection signal is received.

- The control unit identifies that connecting device as the connecting device being in fact connected with the or with one hydraulic line which is selected when the fluid supply detection signal is received. With other words: The control unit tries to establish on a trial base a fluid connection between the fluid source and the hydraulic line via the currently selected connecting device. This attempt is made for every connecting device of the plurality. If a fluid supply detection signal is received, the control unit automatically concludes that the trial was successful and that the selected connecting device is in fact connected with the hydraulic line. The fluid supply detection signal is only generated if a fluid connection between the or at least one hydraulic line and the or at least one fluid source is in fact established. 4. ADVANTAGES

The hydraulic system according to the invention can alternatively be operated in different operating states as the or one hydraulic line can alternatively be connected with several connecting devices of the plurality - one connecting device per time. Every operating state is a proper state, i.e. not an error or a malfunction. The hydraulic system of the embodiment can automatically detect which operating state currently occurs. This distinguishes the hydraulic system according to the invention from other systems which can only detect whether or not a malfunction has occurred.

The detecting method according to the invention releases the need to provide a connecting scheme which specifies for the or every hydraulic line one respective connecting device wherein the actual connections must be established according to this connecting scheme. In contrast several different connections lead to a proper operation as the actual connections are automatically detected.

Thanks to the invention it is not necessary to provide different kinds of connecting devices or different types of corresponding connectors (end pieces) at the hydraulic line(s) such that the or every hydraulic line can only be connected with exactly one connecting device of the plurality. Using only one kind of connecting devices and one kind of connectors makes it easier to manufacture and maintain the agricultural machine and reduces the set of required different spare parts. It is possible to use standardized parts such that the same agricultural implement subsequently with different pulling vehicles.

The hydraulic system according to the invention does not rely on the experience of an operator to connect the or every hydraulic line with a required or desired connecting device of the plurality. In contrast the hydraulic system automatically detects the used connecting device. The operator only needs to connect the or every hydraulic line with a mechanically mating connecting device of the plurality. No connecting scheme is necessary.

The invention provides a very robust solution that does not suffer from any of the disadvantages of the prior art. This will be explained below. The operator of the agricultural machine simply connects the or every hydraulic line of the plurality to one mechanically mating connecting device of the plurality. The or every connection is automatically detected. The control unit automatically performs the connection detection.

The drawbacks of known solutions are avoided by the invention.

Agricultural machines are used in rough situations and in dirty or moist environments and are subjected to all kinds of weather conditions. In particular in case of rainy weather or darkness or dirt on the machine or wear due to mechanical stress, different colors or different patterns of a coding system can often hardly be distinguished from each other. Labels with colors or patterns can be lost. A coding system only provides a limited set of sufficiently different colors or patterns and increases the number of different parts. In addition the rough conditions may quickly damage the electronics of an RFID system. For example the RFID tags may become damaged or dirty, which seriously affects their proper operation.

Another drawback of the use of an RF ID-based system is the following one: The connecting devices of a pulling and supplying vehicle (a tractor, e.g.) are located quite close to each other. This means that also the hydraulic lines with the RFID tags will be close to each other when attached to the vehicle. After connecting the hydraulic lines to the connecting devices the RFID tags will be close to neighboring RFID readers. This proximity may give rise to false readings and consequently give rise to incorrect connection information provided to the controller of the pulling vehicle. Proper functioning and control of the agricultural machine attached thereto will than not be possible. The invention avoids this disadvantage.

The hydraulic system according to the invention can automatically identify that connecting device which is in fact connected by using a detection device which can be positioned in the interior of the agricultural machine. This detection device is therefore less subjected to the environmental conditions. At least a part of the detection device can be positioned quite far away from the connecting devices and the corresponding connectors (end pieces) of the hydraulic lines.

The detection device according to the invention only needs to monitor the or every connectable hydraulic line but does not need to process signals from a sensor for the connecting devices. In particular no contact sensor is required wherein the contact sensor measures whether or not a connecting device is in fact connected with a hydraulic line. The control unit needs only to be connected with the detection device but does not require signals from a sensor for monitoring the connecting devices. Therefore the invention saves a sensor for the connecting devices.

In addition the detection device needs not to detect the fluid source. It suffices that the detection device decides whether or not the or every connectable hydraulic line is currently supplied with fluid. For this detection it suffices to monitor the hydraulic line itself. These features are in particular of advantage if the parts of the hydraulic system are distributed onto two different vehicles, e.g. onto a tractor and an implement, which can mechanically and hydraulically be connected with each other and can be disconnected again. The detecting device can entirely be mounted on board of the implement.

The hydraulic system according to the invention only requires a quite simple detection device. This detection device only needs to detect whether or not a hydraulic line is supplied with fluid. It is not necessary to measure the hydraulic pressure or even to compare measured hydraulic pressures in different parts of a machine or at different time points. Thereby the detection device only requires simple sensors. Often such sensors are already implemented on board of the agricultural machine.

The connection detection according to the invention does not restrict the number of connecting devices or hydraulic lines which can be used. Thereby the invention overcomes one disadvantage of a coding system.

It is possible to use the invention several times for different implements which are subsequently connected with the same pulling vehicle. In turn it is possible to use the invention several times for the same implement which is subsequently connected with different pulling vehicles. 5. PREFERED EMBODIMENTS

According to the invention the control unit establishes a fluid connection between the or one fluid source and the selected connecting device. Preferably the control unit blocks or interrupts the fluid connection between the fluid source and all other connecting devices of the plurality.

Different implementations are possible how a fluid connection between the fluid source and exactly one connecting device is established. In one implementation the control unit moves a switch in a hydraulic line or a switch for a port or actuates a multi-port valve positioned in a hydraulic connection between the fluid source and the connecting devices of the plurality. In a further implementation a plurality of fluid lines connects the fluid source with the connecting devices of the plurality. A respective valve is assigned to every fluid line. The control unit triggers these valves. After selecting a connecting device, the control unit opens the valve assigned to the fluid line guiding to the selected connecting device and closes or keeps closed every other valve assigned to an other fluid line. If the invention is used in a combination comprising a pulling vehicle and an implement, the connecting devices, the fluid lines, the valves, and the multi-port valve are preferably mounted on board of the pulling vehicle.

According to one embodiment of the invention use is made of the presence of hydraulic pressure in the or in at least one hydraulic line as an indicator that the hydraulic line is supplied with fluid. The control unit triggers a hydraulic pressure generator, e.g. a hydraulic pump, belonging to the fluid source. Thereby fluid is ejected under pressure out of the or at least one fluid source towards the connecting devices. For detecting the connection device connected with the hydraulic line, the control unit pressurizes one after the other in a subsequent manner the connecting devices, e.g. by positioning a multi-port valve or by opening and closing valves. This hydraulic pressure is transmitted to the or to at least one connected hydraulic line. A pressure detection signal is generated if a pressure above a given threshold is detected. Thereby the receipt of a pressure detection signal sent by the detection device will allow the control unit to positively detect what connecting device of the plurality is in fact connected to the or to one hydraulic line of the agricultural machine. This pressure detection signal serves as the fluid supply detection signal. According to the invention the detection device generates a fluid supply detection signal if the detection device detects that the or one hydraulic line is supplied with fluid. Preferably the detection device generates a non-detection signal if it is detected that a hydraulic line is not supplied with fluid. This embodiment enables to detect a malfunction: If the control unit neither receives the or at least one fluid supply detection signal nor the or at least one non-detection signal, a malfunction has occurred, e.g. a failure of the detection device or an interruption in the signal transmission. Receiving simultaneously several fluid supply detection signals can also be a clue for a malfunction. If the control unit receives only non-detection signals, it is clear that no hydraulic line is connected with a connection device.

According to an application of the invention the agricultural machine comprises a plurality of hydraulic lines that are each connectable to at least one connecting devices of the plurality - one hydraulic line with one connecting device per time. In one application the number of hydraulic lines is smaller than the number of available connecting devices. In a further application these two numbers are equal. In both applications at least one hydraulic line can properly be connected with several connecting devices - of course only with one connecting device per time.

Usually an agricultural implement, such as a haymaking machine or a rake or a baler or a loader wagon, is provided with more than one hydraulic line. For operating the implement every hydraulic line or at least several hydraulic lines needs to be connected to the or to one fluid source on board of a pulling vehicle. Therefore several connecting devices which are also mounted on the pulling vehicle will be connected with hydraulic lines. After being properly connected, the plurality of hydraulic lines guides fluid to several movable parts of the implement.

In one embodiment the detecting procedure is shortened. According to this embodiment the maximal number of hydraulic lines which are to be connected with connecting devices is given or is detected in advance. This number may even be 1 . The control unit counts the number of fluid supply detection signals. As soon as the received signal number reaches the given or detected maximal line number, the detection procedure is terminated. It is now clear for every hydraulic line to be connected the respective connecting device is detected. In one application of the invention the hydraulic lines and the detection device are arranged on board of the implement. Every implement- mounted hydraulic line guides fluid to at least one implement part to be supplied with fluid. The control unit is preferably arranged on board of a pulling vehicle, e.g. on board of a tractor.

In such a situation it is not enough to "know" which connecting device is indeed connected to a hydraulic line. In addition the control unit must also "know" which specific hydraulic line of the implement is connected to which connecting device on the pulling vehicle. If this requirement is fulfilled, the control unit can supply an implement part with fluid just by pressurizing one connecting device wherein the control unit does not need to obtain access directly to an implement part. It suffices that the control unit receives signals from the detection device.

In order to enable this automatic detection, data that is unique for each hydraulic line is included in every fluid supply detection signal that is provided to the control unit, e.g. to an tractor controller or implement controller. In this embodiment the detection device is arranged to include data unique for each hydraulic line in the fluid supply detection signal upon detection of a fluid connection in that hydraulic line. Preferably such data included in the fluid supply detection signal comprises hydraulic line identification data or sensor identification data so that each hydraulic line or sensor can automatically be identified.

In one implementation a respective fluid supply detection sensor is assigned to every hydraulic line, i.e. every hydraulic line has its own sensor. Every sensor has a unique identifier, i.e. an identifier which at least distinguishes this sensor from every other fluid supply detection sensor on board of this machine. If a sensor detects fluid supply, the identifier of this sensor is included into the generated fluid supply detection signal. A hydraulic line is identified by the identifier of the assigned sensor. In a further implementation the fluid supply detection signal includes an identifier of that implement part which is connected with the hydraulic line and is thereby in fact supplied with fluid. For sake of redundancy both implementations can be combined.

According to an embodiment the fluid supply detection signal can further comprise data characterizing a hydraulic part or assembly on the machine that is connected to a respective hydraulic line. In other words: The fluid supply detection signal comprises data relating to the type of hydraulic part or assembly on the agricultural machine or the specific hydraulic consumer of hydraulic energy that is to be supplied with fluid via the connecting devices. Such information will consequently, together with the fluid supply detection signal, be provided to the control unit.

Preferably the hydraulic part or assembly of the machine comprises at least one hydraulic piston-cylinder device or a group of hydraulic piston-cylinder devices. The transmitted data can characterize the required pressure or the required time span for activating the piston-cylinder device.

In one implementation the identifier of the implement part is determined as follows: A controller on board of the implement generates a computer-accessible table which assigns to every hydraulic line or to every fluid supply detection sensor assigned to a hydraulic line on board of the implement an identifier of the implement part or the parts connected with this hydraulic line. This implement-mounted table is generated before the first implement operation is performed. It remains constant as long as the construction and implementation of the implement remains unchanged. As long as the hydraulic assembly remains unchanged, the same table can be used for several implement operations. The table is updated if the hydraulic assembly on board of the implement is changed.

The embodiment that an implement part identifier is included into the fluid supply detection signal enables to design the implement as a black box: The control unit on board of the pulling vehicle does not need data about hydraulic connections on board of the implement. In particular any connecting information about hydraulic lines and valves on board of the implement is not needed. A sensor for detecting fluid supply needs not to be integrated into the implement part itself but can be connected with an implement-mounted hydraulic line.

According to an embodiment the agricultural machine comprises a plurality of hydraulic lines, a fluid pressure generator and a machine controller. The machine controller is arranged to control a connection between the or every hydraulic line of the plurality and the detection device. By arranging the controller such that it controls the connection between the hydraulic lines and the detection device it is possible to alternately connect the detection device to every hydraulic line of the plurality and thus to alternately sample the pressure (in general: the presence of fluid supply) in the connected hydraulic line. In one implementation the detection device comprises a single pressure sensor that is operatively connectable to each hydraulic line and is arranged to alternately sample the pressure in each hydraulic line. In this manner a very simple arrangement is provided that is able to sample or detect the presence of hydraulic pressure in the respective hydraulic lines, yielding a simple and robust system. Only one pressure sensor is needed.

According to an embodiment the detection device comprises multiple pressure sensors or further fluid supply detection sensors wherein each sensor is connected or is arranged to be connected or otherwise assigned to one hydraulic line of the plurality. This provides a system wherein each hydraulic line has its own dedicated fluid supply detection sensor which in turn provides an even further simplified system for connection detection.

According to an embodiment the agricultural machine comprises an operating device, i.e. a device that can be actuated by a human operator and can be used to control the operation of the agricultural machine and that is operatively connected to the control unit. The control unit assigns, on the basis of the fluid supply detection signal, a specific hydraulic fluid connection to a specific function of the machine and/or displays information relating thereto to the operator. In this way the fluid connection that is detected is used to assign specific functions to the control unit or operating device. For example, the command to actuate a certain hydraulic group or assembly is assigned to a certain control button or lever in a user terminal of the agricultural machine without the need for the operator to manually assign these functions or to test and try which control function has what effect on the machine. This greatly simplifies operation of the agricultural machine.

The intended use of the invention is that a machine part is connected with the hydraulic line and is supplied with fluid. In one application the machine part is driven by the hydraulic or pneumatic fluid which is supplied via the provided fluid connection. The hydraulic fluid is supplied to the machine part with a sufficient pressure. In further applications the fluid serves for greasing or lubricating or cooling or heating or washing or otherwise cleaning or drying or moistening the part. The fluid can be a liquid or a gas, e.g. an oil or a dissolving or cooling liquid or pressurized air.

The invention can be used on board of an agricultural combination comprising an agricultural implement and a pulling tractor or further pulling vehicle. The implement can be a non-propelled vehicle or an attachment without ground- engaging wheels and is mechanically connected with the pulling vehicle. The or every fluid source and the connecting devices are arranged on board of the pulling vehicle. The fluid source is connected to or is connectable with every connecting device belonging to the pulling vehicle. The or every hydraulic line belongs to the implement.

In one implementation the agricultural machine comprises a motorized vehicle and an attachment, e.g. an implement with or without wheels rolling over ground. The or every fluid source and every connecting device of the plurality are mounted on board of the vehicle. The or every hydraulic line and at least one part to be supplied with fluid are mounted on board of the implement or further attachment. Preferably the detection device is also mounted on board of the implement. The control unit can comprise an implement controller which is connected with the detecting device and a vehicle controller which can be connected with the implement controller. In a further embodiment all parts of the hydraulic system - or at least all mechanical parts - are arranged on board of the same vehicle which serves as the agricultural machine. It is also possible that the control unit is arranged on board of a remote device, e.g. on a portable computer.

These and other aspects of the invention and of the preferred embodiment will be even more apparent from the detailed embodiment as described below and will be elucidated in detail there.

6. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows schematically a block diagram of the hydraulic system;

Fig. 2 shows the operation of the control units and the detection device by means of a flow diagram.

7. DETAILED DESCRIPTION OF EMBODIMENT

In the embodiment the invention is used in an agricultural combination comprising a tractor 1 and an agricultural implement 2, cf. Fig. 1 . The implement 2 performs at least one agricultural function, e.g. picks up crop material from the ground and presses bales from the picked-up crop material or threshes the crop material or stores the picked up crop material in a storage room or makes hay or mows grass or processes the soil or distributes seed corns over the ground or distributes a substrate to the soil. The implement 2 performs the agricultural function by means of several rotated or otherwise moved parts which are driven by a pressurized hydraulic fluid.

In the embodiment the implement 2 does not comprise an own motor but is pulled by the tractor 1 . The implement 2 also does not comprise a source for pressurized hydraulic fluid. The implement 2 is connected with the pulling tractor 1 in several ways:

- The implement 2 is mechanically connected with the tractor 1 via an implement towing unit and a corresponding tractor hitch (not shown) such that the tractor 1 can pull or shift the implement 2 over ground.

- A PTO shaft of the tractor 1 rotates a connected input shaft (not shown) of the implement 2.

- The tractor 1 supplies some moved parts of the implement 2 with pressurized hydraulic fluid (to be explained below).

- A data connection (sketched in Fig. 1 ) is established between the control unit 7 of the tractor and the control unit 12 of the implement 2. Preferably this data connection operates according to the ISO bus standard (ISO 1 1783).

The block diagram of Fig. 1 shows schematically a tractor motor 21 and three moveable parts 1 1 .1 , 1 1 .2, and 1 1 .3 of the implement 2 which are hydraulically driven by the tractor motor 21 via fluid connections. Of course the invention can be used for every other number of driven parts on board of the implement 2.

Possible examples for such parts are piston-cylinder devices which drive or pivot a pick-up unit, a tailgate, a roller, a wrapping material holder, and/or a flap. One hydraulically driven part can also tension a pressing belt surrounding a drum-shaped bale forming chamber or a pivotal sidewall of a rectangular pressing channel or a crop material conveyor belt, e.g.

Every piston-cylinder device 1 1 .1 , 1 1.2, 1 1 .3 is only activated temporarily depending on the achieved progress while performing the agricultural function and/or depending on a corresponding input from a human operator.

For activating or otherwise moving a hydraulically driven implement part 1 1 .1 , 1 1 .2, 1 1.3, a fluid connection to a fluid source on board of the tractor 1 has to be established. The hydraulic system of the embodiment provides this fluid connection and comprises the following parts, cf. Fig. 1 :

- a source 3 for pressurized hydraulic fluid, the fluid source 3 comprising a fluid reservoir 4 and a fluid pump 5 wherein the fluid source 3 is mounted on board of the tractor 1 and the pump 5 is driven by the tractor motor 21 ,

- three connecting devices 6.1 , 6.2, 6.3 mounted in a rear wall of the tractor 1 ,

- three parallel hydraulic lines 14.1 , 14.2, 14.3 beginning in the fluid source 3 and mounted on board of the tractor 1 wherein every hydraulic line 14.x connects the fluid source 3 with one connecting device 6.y,

- three valves 13.1 , 13.2, 13.3 in the three tractor-mounted hydraulic lines 14.1 , 14.2, 14.3 - one valve per line wherein every valve 13.1 , 13.2, 13.3 can close the assigned line,

- three parallel hydraulic lines 10.1 , 10.2, 10.3 belonging to the implement 2 and guiding to the three driven implement parts 1 1 .1 , 1 1.2, 1 1.3,

- three connectors (end pieces) 9.1 , 9.2, 9.3 mounted at the free ends of the three implement-mounted lines 10.1 , 10.2, 10.3 - one connector per line,

- three pressure detection sensors 15.1 , 15.2, 15.3 in or at the implement- mounted hydraulic lines 10.1 , 10.2, 10.3 - one pressure detection sensor 15.1 , 15.2, 15.3 per implement-mounted hydraulic line 10.1 , 10.2, 10.3,

- a control unit 7 of the tractor 1 ,

- a control unit 12 of the implement 2, and

- an evaluating unit 20 mounted on board of the implement 2 and arranged to evaluate signals from the pressure detection sensors 15.1 , 15.2, 15.3 and to transmit signals to the implement control unit 12.

In the embodiment every connector 9.1 , 9.2, 9.3 of the implement 2 can be connected with every connecting device 6.1 , 6.2, 6.3 of the tractor 1 - of course only one connector 9.x with one connecting device 6.y per time.

Of course it is possible that a smaller or larger number of hydraulic lines 10.x with connectors 9.x on board of the implement 2 or a smaller or larger number of connecting devices 6.y on board of the tractor 1 are used. The number of tractor-mounted connecting devices 6.y can differ from the number of implement-mounted connectors 9.x. It is also possible that one line 10.x supplies several implement parts 1 1 .x1 , 1 1 .x2 with fluid. During operation the tractor control unit 7 selects and activates at least one hydraulically driven implement part 1 1.x. In the embodiment every implement part 1 1 .x is activated as follows:

- The implement part 1 1.x is connected with the fluid source 3 via the following fluid connection: assigned implement-mounted hydraulic line 10.x, connector 9.x of the line 10.x, a connection device 6.y currently connected with the connector 9.x, and the tractor-mounted hydraulic line 14.y wherein the assigned valve 13.y is open.

- By applying the detection method describe below the tractor control unit 7 "knows" what connecting device 6.y is currently connected with the connector 9.x.

- The tractor control unit 7 opens the tractor-mounted valve 13.y in the line 14.y guiding to this connecting device 6.y.

- Fluid is ejected out of the fluid source 3 and is guided from the fluid source 3 via the line 14.y, the connecting device 6.y, the connector 9.x, and the line

10.x to the selected implement part 1 1 .x. The implement part 1 1 .x is moved by the pressurized supplied fluid.

In the following the detection method of the embodiment is described. This detection method is performed after the human operator has connected every implement-mounted connector 9.1 , 9.2, ... with a mechanically mating connecting device 6.1 , 6.2, ... . In the embodiment the operator can arbitrarily connect the connectors with the connecting devices.

In one implementation every pressure detection sensor 15.1 , 15.2, 15.3 is implemented as a pressure valve which is positioned in the respective implement-mounted hydraulic line 10.1 , 10.2, 10.3. If hydraulic pressure is applied to the line 10.1 , 10.2, 10.3, the respective pressure valve 15.1 , 15.2, 15.3 is triggered and generates a pressure detection signal serving as a fluid supply detection signal. It is possible but not necessary that the pressure valve 15.1 , 15.2, 15.3 opens the assigned hydraulic line 10.1 , 10.2, 10.3 while the connection detection is performed. It is also possible that every pressure valve 15.1 , 15.2, 15.3 remains closed while the detection method is performed. After having finished the detection method the implement control unit 12 preferably opens every implement-mounted valve 15.1 , 15.2, ... In one embodiment the pressure detection sensor 15.1 , 15.2, 15.3 measures the achieved hydraulic pressure. The fluid supply detection signal for this line 10.1 , 10.2, 10.3 is generated if the measured pressure is above a given threshold.

The evaluating unit 20 receives signals from the pressure detection sensors 15.1 , 15.2, 15.3 and automatically evaluates these received signals. The evaluating unit 20 generates output signals depending on the received sensor signals and transmits the automatically generated output signals to the implement control unit 12. The implement control unit 12 receives output signals which are transmitted from the evaluating unit 20. The implement-mounted sensors 15.1 , 15.2, 15.3, the evaluation unit 20, and the implement control unit 12 are preferably connected by means of a data bus, e.g. a CAN bus, or by point-to-point data connections.

The implement control unit 12 transmits received output signals to the tractor control unit 7. The tractor control unit 7 and the implement control unit 12 are connected via a data connection, e.g. a connection according to the ISObus standard (ISO 1 1783). This connection is sketched in Fig. 1 . The connection can be established by means of a wired data connection to be established by the operator or in a wireless manner.

The tractor control unit 7 generates control inputs for the controllable valves 13.1 , 13.2, 13.3 in the tractor-mounted hydraulic lines 14.1 , 14.2, 14.3. Every control input opens or closes at least one valve 13.1 , 13.2, 13.3. In one implementation the tractor control unit 7 switches off the pump 5 if all valves 13.1 , 13.2, 13.3 are closed. The tractor control unit 7 switches on the pump 5 if it at least one valve 13.1 , 13.2, 13.3 is open or is to be opened. A fluid connection between the fluid source 3 and a connecting device 6.x is established by the event that the valve 13.x in the corresponding tractor-mounted hydraulic line 14.x is opened. It is possible that the tractor control unit 7 generates a confirmation message which is transmitted to the implement control unit 12.

When the implement 2 has just been connected with the tractor 1 , all controllable valves 13.1 , 13.2, 13.3 are closed. Before starting the required agricultural functions, a human operator manually connects the implement- mounted connectors 9.1 , 9.2, 9.3 with mechanically mating tractor-mounted connecting devices 6.1 , 6.2, 6.3. These connecting devices 6.1 , 6.2, 6.3 serve as hydraulic pressure supply connecting devices for the implements parts 1 1 .1 , 1 1 .2, 1 1 .3.

Different colors may help the operator to connect the connectors with the proper connecting devices. But the invention does not require using such colors. It is also possible that the operator connects the connectors 9.1 , 9.2, ... with the connecting devices 6.1 , 6.2, ... randomly or such that the lowest mechanical tension or stress is applied to the hydraulic lines 10.1 , 10.2, ... The control unit 7 automatically detects the created hydraulic connections between connectors and connecting devices.

As soon as the operator has connected the connectors with the connecting devices, the following steps are performed automatically for every tractor-mounted connecting device 6.1 , 6.2, 6.3 - for one connecting device 6.x after the other:

- The tractor control unit 7 selects the connecting device 6.x for being pressurized on a trial base.

- The tractor control unit 7 opens the corresponding valve 13.x in the tractor- mounted hydraulic line 14.x guiding from the fluid source 3 to the selected connecting device 6.x. The other tractor-mounted valves 13.z (z≠ x) remain closed.

- The fluid source 3 ejects fluid into the lines 14.1 , 14.2, 14.3. Fluid is guided through the opened valve 13.x to the selected connecting device 6.x, i.e. the selected connecting device 6.x is pressurized. Thanks to the closed further valves the further connecting devices 6.z (z≠ x) are not supplied with fluid.

- Later the tractor control unit 7 closes the valve 13.x again.

It is also possible that the valves 13.1 , 13.2, 13.3 are arranged in the interior of the connecting devices 6.1 , 6.2, 6.3.

Either exactly one connector 9.y is currently connected with the selected connecting device 6.x. Or no connector is currently connected with the selected connecting device 6.x - it is possible that there are more connecting devices than connectors or that the operator did not connect every connector with a connecting device.

In the case that the connecting device 6.x is in fact connected with an implement-mounted connector 9.y, fluid is guided from the fluid source 3 through the connecting device 6.x, the connector 9.y, and the corresponding implement- mounted hydraulic line 10.y to the corresponding pressure detection sensor 15.y. The assigned pressure detection sensor 15.y in the implement-mounted hydraulic line 10.y is triggered and generates a pressure detection signal. This pressure detection signal is transmitted to the evaluating unit 20. The evaluating unit 20 detects the pressure detection signal and further detects automatically what pressure detection sensor 15.y has generated this pressure detection signal.

In one implementation the evaluating unit 20 has one specific signal input port for every pressure detection sensor 15.z and detects that signal input port over which the pressure detection signal is transmitted. In Fig. 1 three signal input ports for the three exemplary sensors 15.1 , 15.2, 15.3 are shown.

In a further implementation (not shown) every pressure detection sensor 15.z (z = 1 , 2, ... ) has a unique identifier which distinguishes this pressure detection sensor 15.z from every other pressure detection sensor - at least from every other pressure detection sensor assigned to a hydraulic line 10.1 , 10.2, ... on board of the implement 2. The pressure detection sensor 15.1 , 15.2, 15.3 generates a pressure detection signal which includes the own identifier, i.e. the identifier of that pressure detection sensor 15.1 , 15.2, 15.3 having generated the signal. This pressure detection signal including the sensor identifier is transmitted to the evaluating unit 20 via a data bus, e.g. a CAN bus, or via a point-to-point connection on board of the implement 2 or via a wireless connection. The sensor identifier enables the evaluating unit 20 to identify that sensor 15.y which has generated the fluid supply detection signal. This implementation only needs one signal input port for the evaluating unit 20.

Preferably every other pressure detection sensor 15.z (z ≠ y) generates a non-detection signal in the case that no fluid pressure is detected in the assigned hydraulic line 10.z. This implementation enables that the evaluating unit 20 automatically detects a faulty pressure detection sensor which does not transmit signals or transmits wrong signals. If several pressure detection sensors simultaneously generate pressure detection signals, one sensor may malfunction. The evaluating unit 20 can further detect an undesired interruption of a signal transfer. The evaluating unit 20 distinguishes the case of a faulty pressure detection sensor or a faulty interruption from the non-faulty case that no connector 9.1 , 9.2, ... is connected with the selected connecting device 6.x. In this case every pressure detection sensor 15.1 , 15.2, ... delivers a non-detecting signal.

When receiving exactly one pressure detection signal, the evaluating unit 20 generates a fluid supply detection signal including an included identifier of the sending pressure detection sensor 15.y. This sensor identifier distinguishes the triggered and sending pressure detection sensor 15.y from every other pressure detection sensor 15.z (z≠ y). Preferably the evaluating unit 20 generates a non-detection signal - provided that every pressure detection signal has provided a non-detection signal.

The generated fluid supply detection signal including an included identifier or the generated non-detection signal is transmitted to the implement control unit 12. The implement control unit 12 evaluates the signals received from the evaluating unit 20.

In one implementation the implement control unit 12 generates a fluid supply detection signal including the sensor identifier of that pressure detection sensor 15.y which has detected pressure in the corresponding hydraulic line 10.y - or a non-detection signal.

In a further implementation the implement control unit 12 generates either a non-detection signal or a fluid supply detection signal including the identifier of an implement part 1 1.y which is currently supplied with fluid on a trial base. In one implementation the part identifier can distinguish this part item from all other parts on this implement 2.

In a preferred embodiment the part identifier comprises data characterizing the part, e.g. specifying a required hydraulic pressure or the time span over which hydraulic pressure has to be supplied. Two part items of the same part type or performing the same part function can have the same part identifier and the same characterizing data.

For including the part identifier into the fluid supply detection signal the implement control unit 12 evaluates a computer-accessible implement- mounted table providing a correspondence between the pressure detection sensors 15.1 , 15.2, ... and the corresponding implement parts 1 1 .1 , 1 1 .2, ...

Preferably this table is created before the first operation of the implement 2 takes place, namely when the pressure detection sensor 15.1 , 15.2, the hydraulic lines 10.1 , 10.2, ... , and the parts 1 1 .1 , 1 1.2, ... on board of the implement 2 are connected with each other. The table is updated if this connection is amended or if a pressure detection sensor 15.1 , 15.2, ... is replaced with a further one.

The evaluating unit 20 uses the identifier of the sensor 15.y which has detected a fluid connection as an entry into the table and obtains an identifier of the implement part 1 1 .y connected with this sensor 15.y. The evaluating unit 20 generates a fluid supply detection signal including an identifier for the identified part 1 1.y. This fluid supply detection signal including the identifier for the identified part 1 1 .y is transmitted to the implement control unit 12 and further to the tractor control unit 7. The tractor control unit 7 obtains this signal and automatically concludes that the implement part 1 1.y is connected with the currently selected and pressurized connecting device 6.x.

Preferably the implement control unit 12 generates a non-detection signal if no pressure detection signal was transmitted to the evaluating unit 20.

In one implementation the tractor control unit 7 uses the transmitted fluid supply detection signals for automatically creating a tractor-mounted assignment table which assigns to every implement part 1 1 .y the currently connected tractor-mounted connecting device 6.x. In the example of Fig. 1 this generated assignment table looks as follows:

This assignment table is automatically created after the connections between connectors 9.y and connecting devices 6.x are established during the detection method and before the implement 2 is operated.

During operation the assignment table is used as follows: If the tractor control unit 7 selects the implement part 1 1.y as to be supplied with fluid, the tractor control unit 7 determines the connected connecting device 6.x by evaluating the assignment table. The implement parts are the entries into this table. The tractor control unit 7 triggers the step that this connecting device 6.x is pressurized. In one implementation the control unit 7 opens the valve 13.x in the hydraulic line 14.x guiding from the fluid source 3 to the identified connecting device 6.x or in the connecting device 6.x itself. The tractor control unit 7 also uses this tractor-mounted assignment table for deactivating an implement part 1 1 .y.

An activation of the implement part 1 1 .y can be demanded by the operator or automatically be triggered by the tractor control unit 7 executing a control program. It is also possible that the implement control unit 12 triggers the activation of the implement part 1 1 .y and sends a control input request to the tractor control unit 7 via the data connection. This control input request comprises an identifier of the implement part 1 1.y. As a response the tractor control unit 7 pressurizes the connected connection device 6.x. It is possible that the tractor control unit 7 generates a request message for the operator and pressurizes the connection device 6.x after having obtained a releasing input from the operator.

In one implementation the amount of fluid required for driving an implement part 1 1 .y depends on the kind of the implement part 1 1 .y. In this implementation the tractor control unit 7 determines the required fluid pressure by determining the kind of the part 1 1 .y and pressurizes the assigned and connected connecting device 6.x with this pressure amount. This kind is determined by evaluating the tractor-mounted assignment table. The assignment table is created by evaluating the characterizing data included into the pressure detection signals.

Fig. 2 shows the operation of the control units 7, 12 and the detection device 15.1 , 15.2, 15.3, 20 by means of a flow diagram. The reference signs in Fig. 2 have the following meanings wherein S denotes a step and D a decision:

tractor control unit 7 selects connecting device 6.x, opens valve 13.x

S1 and closes the other valves 13.z (z≠ x) such that selected connecting device 6.x is supplied with pressurized fluid

assigned pressure detection sensor 15.y determines whether or not

S2 hydraulic pressure is present in implement-mounted hydraulic line

10.y.

pressure detection sensor 15.y generates pressure detection signal

S3

including identifier for this pressure detection sensor 15.y. pressure detection sensor 15.y generates non-detecting signal

S4

including identifier for this pressure detection sensor 15.y. fluid supply detection signal including sensor identifier for 15.y is

S5

transmitted to evaluating unit 20.

S6 non-detection signal including sensor identifier for 15.y is transmitted from sensor 15.y to evaluating unit 20.

evaluating unit 20 counts number of incoming signals from pressure

S7

detection sensors 15.1 , 15.2, 15.3

evaluating unit 20 evaluates received signals from the pressure

S8

detection sensors 15.1 , 15.2, ...

evaluating unit 20 evaluates implement-mounted table and detects identifier of part 1 1 .y connected with line 10.y to which pressure

S9

detection sensor 15.y sending the only pressure detection signal is assigned

S10 evaluating unit 20 generates non-detection signal

evaluating unit 20 generates fluid detection connection signal including

S1 1

identifier of connected implement part 1 1 .y.

fluid supply detection signal including part identifier for 1 1 .y is

S12

transmitted from evaluating unit 20 to implement control unit 12 fluid supply detection signal including part identifier for 1 1 .y is

S13

transmitted from implement control unit 12 to tractor control unit 7 control unit 7 adds the assignment 6.x to 1 1.y in the tractor-mounted

S14

assignment table

non-detection signal is transmitted from evaluating unit 20 to

S15

implement control unit 12

non-detection signal is transmitted from implement control unit 12 to

S16

tractor control unit 7

D1 hydraulic pressure in line 10.y detected by pressure sensor 15.y?

has every pressure detection sensor 15.y transmitted a signal to

D2

evaluating unit 20?

pressure detection signal obtained from how many pressure detection

D3

sensors 15.y?

Reference signs used in the claims will not limit the scope of the claimed invention. The term "comprises" does not exclude other elements or steps. The articles "a", "an", and "one" do not exclude a plurality of elements. Features specified in several depending claims may be combined in an advantageous manner. ENCE SIGNS

tractor

implement

fluid source, comprises the reservoir 4 and the pump 5 reservoir for hydraulic fluid

hydraulic pump, propelled by the tractor motor 21 , ejects hydraulic fluid out of the reservoir 4

connecting devices mounted at the rear wall of the tractor 1 control unit of the tractor 1

user terminal of the tractor 1 , includes an operating device connectors (end pieces) of the implement-mounted hydraulic lines 10.1 , 10.2, 10.3

implement-mounted hydraulic lines, guiding to the hydraulically driven implement parts 1 1 .1 , 1 1 .2, 1 1.3

hydraulically driven implement parts, supplied via the hydraulic lines 10.1 , 10.2, 10.3

control unit of the implement 2

controllable valves in the tractor-mounted hydraulic lines 14.1 , 14.2, 14.3

tractor-mounted hydraulic lines, connect the fluid source 3 with the connecting devices 6.1 , 6.2, 6.3

pressure detection sensors in the implement-mounted hydraulic lines 10.1 , 10.2, 10.3

evaluating unit of the detection device

tractor motor, drives the pump 5