Patent Application
20210204465
The invention refers to the detection of loads acting on the boom of a boom working device.
With such a boom working device, loads are often transferred from the work head to the boom during work, not only by the weight of the work head, especially in dynamic operation, but often because the work head is in contact with the environment during work, and thus, for example, resistance forces are transferred from the environment to the work head and from there to the boom.
A typical example is a boom mower that is used to mow the vegetation on the verge next to a road. The working head is then a mowing head, and usually rests on the ground with one or more sensing rollers and is moved forward by the forward movement of the carrier vehicle.
Depending on the contact force on the ground, the contour of the ground in the direction of travel, the type and quantity of vegetation and other factors, this results in very different loads on the boom.
By knowing these loads, not only the position of the mowing head can be changed, e.g. with regard to the height or inclination of the mowing head in relation to the ground, and for this purpose the positioning elements, which set the relative position of the usually several arm parts of the boom to each other, can be adjusted, but also other parameters, such as the speed of the blade shaft of the mowing head.
Similar tasks also arise with other working devices such as a washing head with rotating brushes as a working head for cleaning the surfaces of sound insulation walls or tunnels.
Often a different working head is attached to the boom for different tasks.
It is well known that sensors for recording the load are placed directly on the working head.
The disadvantage is that a sensor equipment is required at each individual working head used and additionally a data connection from the working head to the boom, unless the data connection from the working head to the control of the boom working device is wireless, which in practice, however, is often failure-prone.
The advantage of this method is that the loads can be measured very close to the place where they occur, i.e. between the ground and the working head.
It is therefore the object according to the invention to create a boom working device which, despite a simple and only one-time construction of the sensor technology, reliably measures the loads at least on the boom, as well as a self-propelled working machine equipped in this sense with such a boom working device.
The object also consists of proposing a method for detecting the loads acting on the boom of a boom working device.
This object is solved by the features of claims 1, 18 and 19. Advantageous forms of embodiments result from the subclaims.
With regard to the boom working device, this initially comprises the boom itself, which usually consists of several arm parts connected pilotable to each other and whose rear end is designed for attachment to a carrier vehicle.
In addition, at its front end the boom has an arm end which can be pivoted in relation to the rest of the boom by means of a Z-joint about an axis known as the Z-axis, and to which the working head can be attached by means of its head end facing the boom, by screwing or locking.
In addition, an X-joint can be provided in the front end area of the boom, by means of which two arm parts can be pivoted relative to each other about an X-axis running transversely, in particular perpendicularly, to the Z-axis. The X-joint can be arranged in front of or behind the Z-joint in the direction of the boom.
Such a boom working device has one, especially only one, load measuring unit with at least one load sensor to detect the loads acting on the boom.
According to invention this load measuring unit is arranged
This has the advantage that the required sensor equipment only has to be available once on the boom working device, especially on the boom, and thus away from the damage-intensive working head.
Although it can only be used to measure the loads acting on the boom, it can be used to draw meaningful conclusions as to how high the loads are that act on the working head from the environment.
Since the load is to be measured not only in one but more in different directions, the load measuring unit contains either several sensors, each measuring the load in only one direction, or at least one load sensor, which can measure the load in several directions, for example the X and Y direction perpendicular to the Z direction.
It is preferable to know all loads acting on the boom at its front end, and therefore the load measuring unit, especially the one or more load sensors, should measure both the forces in X, Y and Z directions and the torsional load, i.e. moments around these three spatial directions.
If the head end of the working head facing the boom is—as is usually the case—fixed to the arm end of the jib in a rotationally fixed manner, the measuring directions of the one or more load sensors always remain the same in their alignment to the working head, so that conclusions can also be drawn about the type and direction of the forces and loads acting on the working head.
Since different working heads can be attached to the boom, which behave quite differently with regard to the loads, it is important that the control unit controlling the boom working device also knows the relevant parameters of the working head, i.e. at least knows which type of working head is currently attached to the boom, in particular which specific working head is involved.
This is because even two mowing heads of the same type can introduce different loads into the boom due to different manufacturing tolerances or different wear conditions when mowing the same vegetation.
For this reason there is at least one detection sensor to detect the working head attached to the boom arm, again
Preferably, there is then a detection sensor in the effective range of this detection sensor at the working head, especially at or in its head end, which the detection sensor can analyze and which contains the desired information regarding the attached working head.
Then, when attaching a working head, there is no longer any need to manually enter such working head-dependent parameters into the controller, which speeds up the work and avoids input errors.
Preferably one of the load sensors with such a detection sensor is functionally cleaned, which reduces the number of necessary sensors and thus the risk of damage.
If the load measuring unit is located on or in the boom, it is preferred
The former option has the advantage that the alignment of the load measuring unit relative to the working head always remains the same, independent of the pivot position of the Z-joint and thus of the front end of the boom, which greatly facilitates the evaluation and analysis of the measured loads with regard to their direction of action on the working head.
The second possibility, i.e. behind the Z-joint, comprises several possibilities if there is an additional X-joint in front:
Individual load sensors or even entire load measuring units can also be present at different locations, especially at a distance along the boom arm, which then preferably measure forces or moments in different spatial directions.
The load measuring unit can also be located between the boom and the working head.
This can be useful if the working head is positively attached to the boom arm by means of a removable connecting element, e.g. a push-in connecting bolt, because then this removable connecting element can support the load measuring unit or be the load measuring unit itself.
The at least one load sensor of the load measuring unit can be a strain gauge or any other electrical sensor that changes its voltage or electrical resistance when loaded.
In order to protect such strain gauges well from damage, they can be arranged in recesses, especially in the front side of the arm end facing the working head or the rear side facing away from it, and in particular they can also be cast in them.
The strain gauges available with different orientations can be connected to each other via an electrical bridge circuit, which, if appropriately arranged, not only allows the loads to be determined linearly in the individual spatial directions, but also torsional loads, i.e. torques, around these three spatial directions can be determined.
Since both strain gauges and related external circuits, especially bridge circuits, are known and can be purchased at low cost, this results in a low-cost load measuring unit.
Instead of installing individual strain gauges, load measuring pins can also be used for the load measuring unit. These can also be purchased on the market and measure the force applied to the load measuring pin preferably in at least one of the transverse directions to the main direction of extension of the load measuring pin and, in particular, output it to the control. On or in such a loadcell, individual strain gauges can be installed as load sensors or other types of load sensors can be used.
Already one single load measuring pin can form such a load measuring unit.
This makes it easier and faster to set up the load measuring unit and of course to change it.
Often a locking pin is used to connect the working head and the boom. This pin is fixed to one of the two parts, usually the boom, and is inserted into a corresponding recess in the other part to couple the two parts, and in this position the two parts are locked together, for example by means of a movable locking element such as a swivel lever, which can preferably be operated from the boom.
This locking pin can then be designed directly as a load measuring pin, for example by mounting a purchased load measuring pin on the supporting components.
With this solution, the total number of existing components of the cantilever-type work unit is not increased by the load measuring unit, and the cantilever-arm-side connection from the load measuring pin to the control unit does not have to be modified when changing the work head.
Occasionally, a removable connecting element, such as a connecting bolt, which connects the two parts positively, is used to connect the working head and boom. This connecting element is inserted through aligned passage openings of bearing blocks, which are attached to the working head on the one hand and the boom on the other hand.
Then again a load measuring bolt can be used as such a connecting bolt without increasing the total number of components.
By arranging preferably several pairs of through-holes and load measuring pins inserted through them, the working head can be arranged in this way at the end of the arm so that it cannot rotate, and further mechanical fasteners can be dispensed with.
Since—especially the low-cost load pins only measure loads in one direction transverse to their longitudinal direction, at least two load pins and thus pairs of through holes will be arranged in two different transverse directions of the X-Y plane perpendicular to the Z-direction, preferably even two redundant load pins in each of these transverse directions.
Depending on the design, load measuring pins can also measure the tensile forces prevailing in their main direction of extension. For this purpose, the load measuring pin must of course be installed in such a way that it has corresponding stops at both ends in order to load it in the longitudinal direction, for example by designing the load measuring pin as a bolt with a nut to be screwed on.
Another possibility is to use a so-called ring force transducer for force measurement and/or torque measurement within the measuring device, which are available on the market.
This is a—usually cylindrical—component, to whose opposite end faces those components can be fastened, usually screwed, so that the ring force transducer measures those forces—in axial direction and/or at least one of the transverse directions to it—which prevail at this connection point between the two components to be connected with each other.
The two end faces of the ring force transducer are usually designed as rings or plates, which are connected to each other by webs or other connecting elements, on or in which the corresponding forces are measured, so that torques about at least one of the radial directions of the ring force transducer, if necessary instead or additionally also about the axial direction of the ring force transducer can be determined from them.
Such a ring force transducer is preferably bolted with its axial direction aligned with the longitudinal direction of the Z-joint between the arm end of the boom and the head end of the working head.
With regard to a self-propelled working machine equipped with a previously described boom working device and where the load measuring unit is arranged and/or designed as described above, the control can thus control the self-propelled working machine on the basis of the signals of the load measuring unit, in particular the load sensors and/or the at least one detection sensor, by
This avoids a damage-endangered arrangement of sensors on the working head itself and it is not necessary to have a separate sensor equipment on each working head.
With regard to the method of detecting the loads acting on the jib arm of a jib working device, especially in the case of a jib working device according to one of the preceding claims,
the load is measured
This also provides the above mentioned advantages.
Types of embodiments according to the invention are described in more detail below as examples. It shows:
For attachment—seen in direction of—vof the working head 2 to be attached, shown in dashed line, is pushed towards the arm end 18a from the right as viewed in the direction of
Arm end 18a and head end 18b must not yet be in the position with their surfaces facing each other, as the working head 2 can still be pivoted around the locking pins 15 in this state.
The working head 2 is only positioned and fixed positively and in a fixed position to the boom 4 by screw connection 25 between arm end 18a and head end 18b, preferably on the other side of the arm end 18a facing away from the locking pin 15.
In this case, the pivoting is effected by means of two positioning elements 60 in the form of hydraulic cylinders, one end of which acts on the arm part 4.3, joint part 12.b, at different points of the circumference.
Each mowing head 2a or 2b is driven by a mowing head motor 22 mounted on it.
Both booms 3, 4 are attached with their rear end to a stem 8 attached to the front of the carrier vehicle 7, in that the stem 8 carries a transverse offset rail 5 on its front side, along each of which a sliding shoe 23, 24 can be moved in transverse direction 19 and can be moved in a controlled manner during operation. One of the booms 4, 3 is attached to each sliding shoe 23, 24.
The booms 3, 4 each consist of several arm parts:
For example, the boom 4 consists of an arm part 4.1, which rises from the sliding shoe 23 approximately in the direction of vertical 11 and can be rotated around a vertical axis and from the free end of which another arm part 4.2 projects and can be rotated around a transverse axis and, analogously, another arm part 4.3.
The angular position of the arm parts to each other is controlled by hydraulic cylinders arranged in between, whereby the respective mowing heads 2a, b, which are additionally articulated around a Z-joint 12 at the front end of the boom 4, can be adjusted to any desired position with regard to direction of travel 10 (X-direction), horizontal cross direction 19 (Y-direction) here towards, as well as rotational position around the Z-axis. By means of a usually existing further X-joint in the boom 3, 4 near its free end, each mowing head 2a, b is additionally pivotable around the direction of travel 10, the X-axis, and can thus be pivoted around all three spatial directions and positioned in all 3 spatial directions as far as the dimensions of the boom 3, 4 allow.
As best shown in
Due to this division, obstacles 9, which are in the area between the mowing widths of the two mowing heads 2a, b, such as road marker posts, can also be mowed around on both sides.
For this purpose, there is usually a feeler bar 21 on the front edge of the front mower head 2a, which is swiveled towards the mower head 2a when striking such an obstacle 9 and thus causes this mower head 2a to fold in around the Z-joint located on the vehicle-side face of this mower head 2a in relation to the boom 3 carrying it.
This mowing head 2b has a housing 16, which is attached in the transverse center via this Z-joint 12 to the free end of the boom 4 so that it can swivel around the Z-axis, which is usually a vertical axis.
Inside the housing 16, which is open at the bottom, a blade shaft 17 is mounted with each of its two ends around a blade shaft axis 17′ in a front flange of the housing 16.
The two locking pins 15—or even just one—are embodied as load measuring bolts 53 and measure the loads acting on these pins.
On or in each of the load-measuring bolts 53, preferably strain gauges 57 are arranged for this purpose, preferably distributed over the circumference, preferably several, in particular in each case in the axial length region, in that the locking elements 20 rest against the locking pin 15, which is designed as a load-measuring bolt 53, so that each of the load-measuring bolts 53 can measure loads occurring on it in the two transverse directions to its longitudinal direction 53′.
By appropriate electronic interconnection of the signals of the strain gages 57, not only forces in these two transverse directions can be measured, but also moments around these two transverse directions and/or around its longitudinal direction 53′ if required.
In a side view,
The load measuring unit 50 may consist of one or preferably several strain gauges 57—then electronically connected to each other via an evaluation circuit—or may comprise one or several load measuring bolts 53—no matter according to which functional principle they function—or may be embodied in any other way, in particular as shown in
Possible positions for arranging such a load measuring unit 50—individually or in total—are shown:
According to
This is a—mostly cylindrical and/or plate-shaped—component 61 available on the market, which can measure forces, depending on the design, mostly in its axial direction and/or also in at least one of its two transverse directions to this, but above all can also measure torques around its longitudinal axis 61′.
In this case, such a ring-shaped force transducer 61 must only be screwed between the e.g. plate-shaped arm end 18a and the e.g. also mostly plate-shaped head end 18b, and the signal line 61a leading away from the ring-shaped force transducer 61 must be connected to the control 1* of the boom working device 1.
The load measuring unit comprises 50 load measuring bolts 53, which are pushed through alternate through-holes of bearing supports, whereby in this case three bearing supports 54, 55, 56 are arranged in series.
As
The bearing support 55 projects between the other two bearing supports 54, 56 in such a way that the through-openings 54a, 55a, 56a in each of the bearing pedestals are aligned with each other, so that the load bolt 53, which fits exactly in there, extends through all three and thus connects the arm end 18a to the arm end 18b at one point.
In the axial direction, axial spacer rings 59 are arranged between the bearing supports 54, 55, 56, which position the bearing blocks and thus the arm end 18a and head end 18b against each other in the axial direction of the load measuring bolts 53.
With only one such connection, this would be a still pivoting connection.
For this reason—as especially shown in the view of
The load measuring bolts 53 thus also serve here as positive-locking connecting elements 58 between head end 18b and arm end 18a.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102019133069.6 | Dec 2019 | DE | national |
