GB2485439A

GB2485439A - Hedge and Grass Cutter with Electronically Controlled Hydraulic Jacks

Info

Publication number: GB2485439A
Application number: GB1117210.3A
Authority: GB
Inventors: Pascal Gautron; Michael Peterschmitt
Original assignee: Kuhn Audureau SAS
Current assignee: Kuhn Audureau SAS
Priority date: 2010-11-10
Filing date: 2011-10-06
Publication date: 2012-05-16
Anticipated expiration: 2031-10-06
Also published as: GB2485439B; GB201117210D0; FR2967011A1; FR2967011B1

Abstract

A hedge and grass cutter comprises a frame and a cutting head 2 arranged at the end of an articulated arm 3. The hedge and grass cutter is characterized in that the cutting head and the articulated arm are moved in space by means of at least one hydraulic jack 8 the stroke of which is servo-controlled in a closed loop in speed and in position via a proportional control, the at least one hydraulic jack is associated with at least one sensor 9 and a control device for the purpose of electronic management. The electronic management makes possible to determine in real time the position of at least one hydraulic jack actuating the articulated arm. The electronic management allows end-of-travel damping of the hydraulic jack.

Description

Hedge and Grass Cutter The invention relates to a hedge and grass cutter with electronically controlled hydraulic jacks.

The maintenance of the banks of roads, railways, canals and verges is generally carried out with hedge and grass cutters. This type of machine comprises a frame supporting a movable cutting head carried by a displaceable arm and which is carried by a vehicle, which vehicle can be an agricultural tractor, for example.

The hedge and grass cutter comprises a cutting head constituted principally by a rotor provided with flails or hammers, a sensor roller, a hydraulic motor and a frame supporting the different elements and which is connected to the arm.

The offset cutting head of the hedge and grass cutters, as the offset tool of other machines, must be able to precisely follow the work surface and avoid obstacles when they arise, so as not to block the machine in its forward movement and so as not to damage the work tools.

For its operation, the cutting head is moved by means of hydraulic jacks, which are carried by the articulated arm connected to the frame. The jacks and the articulations of the arm are intended for allowing movements of the cutting head in as wide a space as possible, so as to solve all the problems set out by the configurations of use of the machine and of the terrains which are to be processed.

During the operation of the cutting head, the various elements actuated by the jacks move at variable speeds, in particular when the articulated arm is designated as "parallelogram", the movements of the boom and of the swinging arm are in relation with one another by means of a connecting rod. In particular with the parallelogram kinematics and more generally during a movement of the arm of a hedge and grass cutter, the lever arms of the jacks change and consequently the angular speeds of the arms change for a given inlet hydraulic flow, which brings about shocks at the ends-of-travel of the jacks, these shocks being damaging to the equipment as they accelerate wear, and unpleasant for the driver of the machine, who experiences the induced impacts and noises.

Although some jacks are equipped with end-of-travel shock-absorbers, the current devices are not sufficiently reliable and, furthermore, their cost is quite high. The use of these jacks therefore sets out an economic problem without entirely solving the technical problem of the damping of the shocks.

Another problem encountered with the hedge and grass cutters currently in use is that the cutting head is not precisely controlled in the environment of the machine.

No means other than visual means exist for the operator to allow him to know where the work tool is located and how the articulated arm is positioned. As a matter of fact, if the driver is distracted or if an orientation problem arises, the cutting head can damage the machine, even injure the driver. The safety of the user and of the equipment is therefore not optimum.

In the known hedge and grass cutters, the articulated arm carrying the cutting head is intended for working in an optimum manner in a position perpendicular to the direction of travel. Today this position is not precisely controlled, which sets out on the one hand a problem of working efficiency during the normal operation of the machine, and on the other hand a problem of safety particularly when the hedge and grass cutter is manoeuvred in reverse direction. In fact, if the driver operates the machine in reverse direction without having raised and folded back the articulated arm, the hydraulic jack can be torn off, which is extremely damaging.

In order to improve the operating safety of the hedge and grass cutters and to increase the lifetime of the equipment, it therefore appears necessary to precisely control the movement of the cutting head, i.e. to control the action of the hydraulic jacks which allow the mobility of the different segments of the articulated arm.

The invention therefore has the object of solving these main problems by proposing new control devices on hedge and grass cutters.

The present invention relates to a hedge and grass cutter comprising a cutting head placed at the end of an articulated arm, the hedge and grass cutter being characterized in that the said cutting head and the said articulated arm are moved in space by means of at least one hydraulic jack, the stroke of which is servo-controlled in a closed loop in speed and in position via a proportional control, and to which hydraulic jack are associated at least one sensor and a control device with the purpose of obtaining an electronic management. The electronic management makes it possible to determine in real time the position of at least one hydraulic jack actuating the said articulated arm. The electronic management is advantageously used on a pivot jack to allow at the same time the end-of-travel damping, the choice of a work position different from the end-of-travel, the automatic return to this work position in the case of movement towards the front or the rear. The electronic management is advantageously used on a parallelogram jack to allow control of the speed of the jack over its entire stroke and, in addition, to control the end-of-travel ofthesaidjack.

The advantages of the electronic management of the hydraulic jacks of the hedge and grass cutter according to the invention are multiple: -the displacement speeds of the jacks can be regulated and adapted as a function of the work which is to be provided, which allows a more flexible operation, -the end-of-travel of the jacks can be damped by avoiding shocks and the related wear problems, the machine also operates less noisily, -the knowledge of the position of the tools of the hedge and grass cutter in space makes it possible to define exclusion zones, if the tool approaches one of these zones, an alarm intended for the driver can be triggered, -the precise control of the movement of the articulated arm allows the risks of accident to be prevented, the existence of the exclusion zones and of the allowed movements makes the use of the hedge and grass cutter more safe, -the positioning of the articulated arm and of the cutting head can be communicated to the driver's cabin, for example through a display device, -the electronic management of the hydraulic jacks allows the use of standard jacks instead ofjacks with end-of-travel shock-absorbers, which constitutes an important economic advantage for the manufacturing of the hedge and grass cutter, whilst removing the drawbacks linked to this equipment.

Other features and advantages of the invention will emerge from the following description with respect to the attached drawings which are given only as non-restrictive examples. In these drawings: -Figure 1 is a rear view of a hedge and grass cutter according to the invention, having an articulated arm with an electronically controlled parallelogram jack.

-Figure 2 is a detail view of figure 1 showing the positioning of the position sensor of the articulated arm.

-Figure 3 illustrates a top view of a hedge and grass cutter having an electronically controlled pivot jack.

-Figure 4 is a detail view of figure 3 showing the positioning of an angle sensor of the articulated arm.

Figure 1 illustrates a hedge and grass cutter according to the invention, in a rear view, carried by a tractor (1) which allows it to be moved in the direction of travel (A) and to be operated. This hedge and grass cutter comprises a cutting head (2) placed at the end of an articulated arm (3) which is fixed on a rocker (4).

The rocker (4) allows the articulated arm to be folded back so as to bring the boom (5) in a raised position close to the vertical. The rocker (4) comprises a connecting rod (6) connected by one end to a connection part (7) on which the end of the boom (5) is fixed.

The displacement of the articulated arm is ensured by a hydraulic jack designated as parallelogram jack (8), which rests by one end on the boom (5) and by the other end on the rocker (4), in a configuration represented in figure 1.

Figure 2 shows the detail of the different elements described above at the level of the rocker (4).

In accordance with the invention, the cutting head (2) and the articulated arm (3) are moved in space by means of at least one hydraulic jack (8), the stroke of which is electronically controlled. In the case of figures 1 and 2, the jack (8) is a parallelogram jack allowing the articulated arm (3), carrying the cutting head (2), to be raised and lowered.

In accordance with the invention, the electronic management is achieved by means of at least one sensor (9) which makes it possible to determine the position of at least one hydraulic jack (8) actuating the articulated arm (3). The stroke of the said jack (8) is servo-controlled in a closed loop in speed and in position via a proportional control of a control device associated with the said sensor (9). In this way, it is possible to control the speed of the jack (8) over its entire stroke and, in addition its end-of-travel.

Several hydraulic jacks can be used on an articulated arm and several sensors can be arranged on each jack so as to precisely determine the positions of the articulated arm (3) and of the cutting head (2).

Figure 2 shows more precisely the positioning of a sensor (9) arranged on the rocker (4) and connected to the boom (5); advantageously according to the invention the angle sensor (9) is positioned between the rocker (4) and the boom (5) of the articulated arm (3).

In accordance with the invention, the sensor can also be a position sensor arranged on the hydraulic jack (8) itself, and different types of sensors can be used for the same purpose without departing from the scope of the invention.

Figure 3 illustrates a hedge and grass cutter according to the invention in top view with an articulated arm (3) carrying a cutting head (2) as in the preceding example.

The said articulated arm (3) is articulated on a base (11) of the frame of the machine by means of a substantially vertical axis (12). The depicted hedge and grass cutter is shown at the start of running in reverse direction, when the articulated arm (3) is no longer perpendicular to the direction of travel (A), i.e. when it is situated in a zone which is becoming dangerous. In this position, it is necessary to be able to have information on the angle of the machine with respect to the articulated arm (3) and for an alarm signal to be triggered or for a locking of the reverse running of the tractor to operate.

The articulated arm (3) is displaceable about the axis (12) by means of a pivot jack (13) connected to the base (11). The stroke of this jack (13) is servo-controlled in a closed loop in speed and in position via a proportional control. At least one sensor (10) and a control device are associated with the said jack (13) for the purpose of obtaining an electronic management. The electronic management is used on the pivot jack (13) to allow at the same time the end-of-travel damping, the choice of a work position which is different from the end-of-travel, the automatic return to this work position in the case of movement towards the front or the rear, for example in the case of actuation of a mechanical or hydraulic security.

Figure 4 is an enlarged view of the connection zone with the rocker (4) and the location of a sensor (10) which makes it possible to determine the angular position of the articulated arm (3) with respect to the base (11) of the frame and to the direction of travel (A). Advantageously, the articulated arm (3) has to be positioned perpendicularly to this same direction of travel, and the control means have to allow a warning to be given that the articulated arm (3) has to be folded back and raised if the driver engages reverse motion, which could lead to damage or a tearing off of the jack (13).

The angle sensor (10) of the articulated arm (3) gives out information which allows the cutting head (2) to operate in an optimum position and to avoid the accident potentially able to occur in the case of reverse motion of the hedge and grass cutter.

In accordance with the invention, the sensor(s) (9, 10), judiciously located for determining the position of the articulated arm (3), send their information to a control device suitable for providing an electronic management of the various hydraulic jacks concerned, via a proportional control.

According to the invention, at least one sensor (9, 10) provides information in real time to a control device acting on the stroke amplitude of at least one hydraulic jack (8, 13).

In the case of control of a single jack, the device is preferentially connected to the hydraulic jack (8) allowing the articulated arm (3) to be raised.

According to another aspect, at least one sensor (9, 10) provides information in real time to a control device acting on the displacement speed of at least one hydraulic jack (8, 13).

The information originating from a single sensor (9 or 10) can make it possible to determine the volume in which the cutting head (2) is located and allows, through the electronic management, an action on several jacks to keep the cutting head (2) in a secured zone.

A sensor (9) is advantageously placed on the rocker (4) as was previously described; it can also be envisaged to arrange sensors on several segments of the articulated arm (3), for example to place at the level of the cutting head (2) another sensor to control the hydraulic jack positioning the said cutting head (2). The information originating from the various sensors are able to be processed by the control device suitable for determining the position of the articulated arm (3) and of the cutting head (2) iii space and for determining the three-dimensional positioning of the elements inside the work space.

The control device is able to determine the locking of the various jacks (8, 13) in case the cutting head (2) would be displaced towards a zone being dangerous for the machine or its driver.

Thus, according to the invention, the control device comprises specifications on the work space for the cutting head (2) and on the possibilities for displacement of the articulated arm (3), which specifications correspond to authorized operating zones and to exclusion zones.

Advantageously, the control device comprises an alarm when the articulated arm (3) is positioned in an exclusion zone or in a configuration outside the safety area, in particular when the reverse motion of the vehicle is engaged.

According to the invention, the control device comprises a system for transmission of information concerning the position of the cutting head (2) and/or of the articulated arm (3) to the driver's cabin of the tractor.

This control device is preferably connected with a display system positioned in the driver's cabin of the tractor carrying the hedge and grass cutter, such that the driver can be visually aware of the position of the articulated arm (3) and/or of the cutting head (2) in real time.

Several variants are possible for the electronic management of the hydraulic jacks without departing from the scope of the invention; it can, for example, be envisaged to arrange a single sensor or several sensors on each hydraulic jack, as was previously described; sensors of different kinds and placed in different ways can also be envisaged, in order to very precisely determine the position of the articulated arm and of the cutting head.

Furthermore, the control of the jacks can be made greatly easier by limiting the strokes of the said jacks and by delimiting exclusion zones which are non-apparent to the driver of tile machine, or consist iii computer management, with display means and controls allowing the user to define to a certain extent the work conditions and the exclusion zones, all without departing from the scope of the invention.

The commumcation of the information, in particular when the articulated arm and the cutting head approach an exclusion zone or are in unsuitable conditions, can be carried out in a simple manner by a sound or light alarm, or be achieved in a more sophisticated manner on a display with complementary written or pictural information, without departing from the scope of the invention.

Claims

Claims 1-Hedge and grass cutter comprising a frame supporting a cutting head placed at the end of an articulated arm, the said cutting head and the said articulated arm being moved in space by means of at least one hydraulic jack to which are associated at least one sensor and a control device with the purpose of obtaining electronic management, wherein the stroke of the said hydraulic jack is servo-controlled in a closed ioop in speed and in position via a proportional control.

2-Hedge and grass cutter according to Claim 1, wherein the electronic management is used on a hydraulic jack to allow at the same time the end-of-travel damping, the choice of a work position different from the end-of-travel, the automatic return to this work position in the case of movement towards the front or the rear.

3-Hedge and grass cutter according to Claim 1 or Claim 2, wherein the electronic management is used on a hydraulic jack to allow control of the speed of the jack over its entire stroke and, in addition, to control the end-of-travel of the said jack.

4-Hedge and grass cutter according to any preceding claim, wherein the electronic management is achieved by means of at least one sensor which makes it possible to determine the position of at least one hydraulic jack actuating the articulated arm.

5-Hedge and grass cutter according to Claim 4, wherein at least one sensor provides information iii real time to a control device acting on the stroke amplitude of at least one hydraulic jack.

6-Hedge and grass cutter according to Claim 4 or Claim 5, wherein at least one sensor provides information in real time to a control device acting on the displacement speed of at least one hydraulic jack.

7-Hedge and grass cutter according to Claim 5 or Claim 6, wherein the control device comprises specifications on the work space for the cutting head and on the possibilities for displacement of the articulated arm, which specifications correspond to authorized operating zones and to exclusion zones.

8-Hedge and grass cutter according to Claim 7, wherein the control device comprises an alarm when the articulated arm is positioned in an exclusion zone or in a configuration outside the safety area, in particular when the reverse motion of the vehicle is engaged.

9-Hedge and grass cutter according to Claim 5 or Claim 6, wherein the control device comprises a system for transmission of information of the position of the cutting head and/or of the articulated arm to the driver's cabin of the tractor.

10-Hedge and grass cutter according to Claim 9, wherein the control device is r connected with a display system positioned in the driver's cabin of the tractor such that the driver of the machine can be visually aware of the position of the articulated arm and/or of the cutting head.

11 -Hedge and grass cutter according to any preceding claim, which comprises a rocker which carries the articulated arm and wherein one said sensor is an angle sensor positioned between the said rocker and the boom of the articulated anm 12-Hedge and grass cutter according to any preceding claim, wherein one said sensor is a position sensor placed on the hydraulic jack itself 13-Hedge and grass cutter according to any one of Claims 1 to 10, wherein one said sensor is an angle sensor positioned between the base of the frame and the articulated arm.