WO2018011016A1

WO2018011016A1 - Agricultural electric mower

Info

Publication number: WO2018011016A1
Application number: PCT/EP2017/066628
Authority: WO
Inventors: Wolfgang Breu
Original assignee: Agco International Gmbh
Priority date: 2016-07-14
Filing date: 2017-07-04
Publication date: 2018-01-18
Also published as: GB201612224D0

Abstract

A control system (12) for a mower (2, 3, 4) is attached to a tractor (t), wherein the said mower (2, 3, 4) comprises at least one rotor (8) to which at least one blade (9) is attached. The at least one rotor (8) comprises an electric motor (11) and electric current supplied to the rotor, indicative of the torque applied to the rotor, is measured by the control system (12). The rotor (8) and tractor (1) are maintained at constant respective operating speeds, and an increase in current detected by the control system (12) indicates a blunt knife and a driver warning (33) is given.

Description

DESCRIPTION

AGRICULTURAL ELECTRIC MOWER

This invention relates to an electrically driven rotatable mower which is attachable to a tractor.

Such an agricultural mower comprises a mower frame which is attachable to a tractor. The frame is fitted to the tractor transverse to the direction of travel of the tractor. The frame supports at least one rotor which is connected to a rotating shaft which rotates about an axis which is substantially vertical to the ground. Each rotor is provided with a mower blade. If the mower frame supports a plurality of rotors, then the rotors are usually mounted in a row across the length of the mower frame. Each rotor is driven by an electrical motor arrangement which is connected lo a power supply on the tractor. An example of an electric mower arrangement is given in the applicant's European patent application EP-A-314 1 100.

During use of the mower, the mower blades become blunt which necessitates sharpening, or replacing. If a mower frame comprises a plurality of rotors, the blades of each rotor may wear differently depending where within the arrangement a rotor is positioned. Typically, the inner rotor blades will wear quicker than the blades of an outer arranged rotor, since the central rotor blades wil l always be mowing fresh crop whereas the outer rotors may be mowing crop which may already have been cut. Mowing over a small amount of crop which has already been cut prevents a strip of unmown crop being left.

It is usual practice for a farmer to assess the sharpness of mower blades by either looking at the blades, or looking at the cut of the crop. This can be inaccurate and may result in blades being sharpened when not required, or blades not being sharpened when required. Where the mower comprises a plurality of rotors, it can also lead to the blades of some of the rotors being sharper than blades on other rotors which in turn leads to an uneven cut and inefficiency since the blunter blades will have to be rotated at a higher speed to give a similar cut to that of the sharper blades.

It is an aim of the invention to provide a system for monitoring the wear of mower blades on an electrical ly driven rotor which is attached to a tractor and which warns a tractor driver when the blades require sharpening. According to a first aspect of the invention there is provided a control system for a mower attached to a tractor wherein said mower comprises at least one rotor to which at least one knife blade is attached, said at least one rotor comprising an electric motor and wherein electric current supplied to the rotor indicative of the torque applied lo the rotor is measured by the control system and wherein when the rotor and tractor are maintained at constant respective operating speeds, an increase in current detected by the control system indicates a blunt knife and the control system is configured to trigger a driver warning.

An increase in torque is indicative of the knife (or knives) becoming blunt during mowing since the knife is meeting greater resistance in cutting the crop and therefore a greater torque is required to cut the crop.

Preferably, the mower comprises more than one rotor and the control system detects the motor current associated with each motor of each rotor. In this way the wear of knives associated with each rotor can be monitored individually. Depending on the location of the rotors in a mufti-rotor mower, the knives of each rotor may wear differently.

The rotors may be al l operated at the same speed and the motor current of each rotor is monitored and wherein if the motor current of one rotor is comparatively higher than the other rotors, the control system is configured to warn the driver about that specific rotor.

According to a further embodiment of the present invention there is provided a method of operating a mower attached to a tractor wherein said mower comprises at least one rotor to which at least one blade is attached and said at least one rotor comprises an electric motor, the method comprising:

- maintaining the rotor and tractor at constant respective operating speeds;

- measuring the electric current supplied to the rotor as indicative of the torque applied to the rotor; and

- triggering a driver warning indicating a blunt knife blade in response to an increase in the measured electric current.

Preferably, a reference current value/torque value is inputted into the system and when that value is reached or exceeded, the driver warning is given. This allows for a certain amount of wear to be permitted without alerting the driver, but when an unacceptable amount of wear is present the driver is warned. More preferably, one or more crop conditions is inputted into the system to adjust the reference current value/torque value. Such conditions may comprise one or more of the following, the type of crop being mowed (e.g cereal or grass), the condition of the crop (whether it is dry or moist), the weather conditions when mowing (whether it is wet or windy or dry) and the topography of the land to be mowed.

The control system may be provided with weather and/or topographical data to adjust the reference current/torque value.

Preferably, driver inputs are inputted via a terminal mounted in a cab of the tractor.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure i is a plan view from above of tractor and mower including a control system in accordance with the invention;

Figure 2 is a perspective view of a mower;

Figure 3 schematically represents components of a control system embodying the present invention; and

Figure 4 represents steps in a method of operating a mower in accordance with a further embodiment of the present invention.

In Figure 1 , a tractor I is shown filled with a front mower 2 and two rear mowers 3, 4. Front mower 2 is positioned centrally forward of the tractor. The two rear mowers 3, 4 are sometimes referred to as butterfly mowers and are arranged so that they extend laterally away from the sides of the tractor. The two rear mowers 3, 4 are each provided with a respective conveyor 5, 6 which serves to transfer cut grass cut laterally at the sides of the tractor towards the centre of the tractor to form a single swathe extending centrally of the tractor.

Referring additionally to Figure 2, which is a perspective view of rear mower 3, each mower

2, 3, 4 comprises a mower frame 7 which supports at least one rotor 8. Each rotor 8 is provided with a knife blade, or blades 9. The mower frames are attached to the tractor by respective linkages. Where a mower frame 7 comprises more than one rotor 8, the rotors 8 are arranged in a row along the length of the frame as shown.

Referring additionally to Figure 3, each rotor comprises an electric motor 1 1 of the type described in EP-A-3 14 1 100. Each motor is supplied with electricity VIN from the tractor.

Each rotor can be controlled separately from the others by the driver by means of a control system 12 which is operated by a terminal 13 mounted in the cab 10 of the tractor. The control system 12 is a programmable unit comprising a cenlral processing unit (CPU) 20 coupled to a storage device 22 (which storage device holds the operating software of the CPU) via an address and data bus 24. Further storage in the form of random access memory 26 is coupled to the CPU 20 (via bus 24) for storing e.g. data input by a user via the in-cab terminal 13, as will be described further below. As will be appreciated, other data storage devices such as disk drives or memory sticks may also be used. Also, although shown as a discrete unit in Figure 3, it will be appreciated thai the components may distributed, for example with the CPU functionality handled as a subset of an overall control system for the tractor and, where wireless communications are enabled, data storage may occur at a location remote from the tractor or in the cloud.

Also coupled to the CPU 20 via bus 24 are interfaces for control input/output 28, sensor input 30, and user input/output 32 as will be described further below. User input commands for control of each rotor may be provided to the control system via the user terminal 13 suitably a touch-screen display and input device) connected to user input/output 32. From control input/output 28, a respective control line runs from the control system 12 to each rotor motor I I . It will be understood that, rather than the separate supplies as shown, the control lines may also carry the supply V_iN to the motors 1 1.

By means of a respective sensor 14 coupled to the CPU 20 via sensor interface 30 and bus 24, which sensor 14 measures the respective current supplied to each motor 1 1 , the speed and the torque applied to each rotor 8 can be calculated in CPU 20 on the basis of a calculation routine stored in ROM 22.

In operation, as represented by the flowchart of Figure 4, in a first step 40 the tractor is moving at a constant speed whilst mowing and a rotor or rotors 8 of a specific mower 2,3,4 are operated to rotate at a set constant speed. In a subsequent step 42, a measured increase in corrent drawn by each electric motor 1 1 to maintain the constant speed of the respective rotor indicates an increase it torque applied to the respective rotor. The increase in torque is indicative of the knife or knives of that respective rotor becoming blunt during mowing since the knife is meeting greater resistance in cutting the crop and therefore a greater torque is required to cut the crop, if the rotor is to maintain its constant set speed.

In one embodiment of the invention where the mower 2, 3, 4 has a plurality of rotors 8, the rotors are specified (via the terminal 13) to operate at the same speed. Through sensors 14, the control system 12 monitors the current drawn by each motor 1 1 of a respective rotor. If one motor 1 1 is drawing a comparatively higher current than (he other motors, as determined at Figure 4 step 42, the control system 12 creates a signal to send a warning to the driver via the terminal 13 to check the rotor concerned for bluntness of the knives or knife blade of that rotor 8 (Figure 4 step 44). The warning may take the form of a visual warning on the terminal 13 screen and/or an aural warning, either via the terminal or through a separate alarm device 33 coupled to the control system 12 via user input/output interface 32,

In a second embodiment of the invention the terminal 13 is inputted with a reference value being a current or torque value for the electric motor{s), as represented in Figure 4 at step 48. This value represents an upper limit and, if it is reached or exceeded whilst mowing at a constant ground speed and whilst maintaining a constant rotor speed, the control system creates or triggers a warning signal for the driver as already described (Figure 4 steps 42, 44). Reaching, or exceeding the reference value indicates that the knife or knives require sharpening.

The type of crop being mowed (e.g. cereal or grass), the condition of the crop (whether it is dry or moist), the weather conditions when mowing (whether it is wet or windy or dry) and the topography of the land to be mowed impact on the torque required to rotate the rotor to maintain a set rotor speed. These factors will therefore affect the reference value lo be inputted. These factors (Figure 4 step 50) can be inputted into the control system by the driver so that they vary (Figure 4 step 52) the reference value accordingly. Alternatively, the control system 12 may access data of these factors from other sources, such as weather data from the internet, sensors on the tractor which detect the crop type and condition and/or map data already stored in the control system.

In the foregoing the applicants have described a system for detecting wear or bluntness of a knife blade, or knives, of a mower attached to a tractor and bringing this matter lo the attention of the driver of the tractor. A control system is provided for the mower attached to the tractor, wherein the mower comprises at least one rotor lo which at least one blade is attached. The at least one rotor comprises an electric motor and electric current supplied to the rotor, indicative of the torque applied to the rotor, is measured by the control system. The rotor and tractor are maintained at constant respective operating speeds, and an increase in current detected by the control system indicates a blunt knife and a driver warning is given.

From reading of the present disclosure, other modifications will be apparent to those skilled in the art. Such modifications may involve other features which are already known in the field of agricultural implements and componenl parts therefore and which may be used instead of or in addition to features described herein.

Claims

1. A control system ( 12) for a mower (2, 3, 4) attached to a tractor ( 1) wherein said mower (2, 3, 4) comprises at least one rotor (8) to which at least one knife blade (9) is attached, said at least one rotor (8) comprising an electric motor ( 1 1 ) and wherein electric current supplied to the rotor indicative of the torque applied to the rotor is measured by the control system ( 12) and wherein when the rotor (8) and tractor ( I ) are maintained at constanl respective operating speeds, an increase in current detected ( 14) by the control system ( 12) indicates a blunt knife blade (9) and the control system ( 12) is configured to trigger a driver warning ( 13, 33),

2. A control system as claimed in claim I , wherein the mower (2, 3, 4) comprises more than one rotor (8) and the control system ( 12) detects the motor current associated with the respective motor ( 1 1 ) of each rotor (8).

3. A control system as claimed in claim 2, wherein the rotors (8) are all operated at the same speed and the motor current of each rotor is monitored ( 14) and wherein if the motor current of one rotor (8) is comparatively higher than the other rotors, the control system ( 12) is configured to warn ( 13, 33) the driver about that specific rotor.

4. A control system as claimed in claim 1 or claim 2, wherein user input means ( 13) are provided for a reference current value/torque value to be inputted into the control system ( 12) and stored (26) therein, with a processor unit (20) of the control system being configured to determine when thai value is reached or exceeded and trigger the driver warning.

5. A control system as claimed in claim 4, wherein one or more crop conditions may be input into the control system ( 12) via the user input means ( 13), with the processor unit (20) of the control system being configured to adjust the reference current value/torque value in response.

6. A control system as claimed in claim 4 or claim 5, wherein the control system ( 12) is configured to adjust the reference current/torque value in response to received weather and/or topographical data.

7. A control system as claimed in any of claims 4 to 6, wherein driver inputs are inputted via a terminal ( 13) mounted in a cab ( 10) of the tractor ( 1 ).

8. A method of operating a mower attached to a tractor wherein said mower comprises at least one rotor to which at least one blade is attached and said at least one rotor comprises an electric motor, the method comprising:

- maintaining the rotor and tractor at constant respective operating speeds (40);

- measuring the electric current supplied to the rotor as indicative of the torque applied to the rotor (42); and

- triggering a. driver warning indicating a blunt knife blade in response to an increase in the measured electric current (44).

9. A method of operating a mower as claimed in claim 8, wherein the step of triggering occurs when the measured electric current value/torque value exceeds a user input (46) reference current value/torque value (42).

10. A method of operating a mower as claimed in claim 8 or claim 9, wherein one or more crop conditions is inputted by a user and the reference current value/torque value is adjusted in response.

1 1. A method of operating a mower as claimed in claim 8 or claim 9, wherein the reference current/torque value is adjusted in response to received weather and/or topographical data.