DE102008002626B3 - Pneumatic pruning shear for plantation pomiculture in communal tree care area, has central guide tube whose ends are connected to handrail and cutting head, respectively, and fixing unit for fixing pneumatic cylinder and circular saw - Google Patents

Abstract

The shear has a handrail (8) and a cutting head (9) comprising shear blades (4, 5). The cutting head is formed from a central guide tube (1) and an exterior pneumatic cylinder (2) that is coaxially arranged to the central guide tube. A circular-ring shaped piston comprises a front piston (10), a rear piston (11) and an intermediate circular saw (12), and is formed in the pneumatic cylinder. An end of the guide tube is connected to the handrail, and another end of the guide tube is connected to the head. A fixing unit e.g. thread section, fixes the pneumatic cylinder and the circular saw.

Description

The The invention relates to a pneumatic pruner with handlebar and cutting head with shear blades for cutting branches and branches.

Under a pruning shears should generally be understood as a tool which is used for the cutting of branches and branches of trees and priority based on the shear action as a pair of scissors, but also on the wedge effect. If the shear effect is used, two cutting edges act in such a way, that a shear stress on the material to be cut to its breakage leads. If the wedge effect is used, only one cutting edge acts on the material to be cut against a dull counterpart.

at a secateurs are usually a cutting tool, with the branches and branches to be separated from a tree. Since the work is also in larger heights are to be carried out, is an extension required in the form of a handlebar. At the bottom of the handlebar are For this purpose controls are arranged, with which the scissors at the upper end can be served. To facilitate the work carries one as easy as possible Scissors, which is well manipulated with the rod and a premature fatigue of the workforce prevented.

Pruning shears come next to the wood care especially in fruit growing used. The crop yield in orchards depends essentially from professional pruning at the beginning of each season. The pruning must be in a short Time window of the months March and April become. To organize this is not just a meteorological problem, but also a labor problem. When handling pneumatically operated scissors then count the factors weight, power, largest diameter of knifes, Cutting quality, Range, tool life and reliability the pneumatic drive in the complex. In practice, come hand-operated Lever shears, pneumatic hand shears and with battery operated scissors for use. Depending on the conditions of use the technology to the use of lifting platforms or to the use additional Aids, such as telescopic boom, knotted.

enforced have worked in professional pruning in large orchards pneumatically operated shears. Such scissors are as basic handsets from the ground off, for operation from the mobile lifting platform or as an attachment Telescopic or simple rod holders used as handlebars. These application criteria lead on special requirements for design, handling and drive system and require lightweight construction principles.

Consists the requirement to have greater branch thicknesses in Hochentastung in greater heights on the tree to cut, it is only possible in the prior art, chainsaw plow use. These are gasoline-powered and bring problems on the part of occupational safety. In addition, the resulting cut unclean.

For professional usable pruning shears, nominal in the cutting performance up to 50 mm branch strength are designated, comes the pneumatic drive by means of pneumatic Drive power supply via a compressed air hose from an entrained mobile compressor station for use. These devices are designed very stable due to their stress and therefore because of the high operating weight of more than 5 kg hardly suitable for continuous use.

Devices that separate even stronger branches can, are based on the one rejected in fruit growing because of the risk of infection fraying saw cut.

restrictive Health and safety regulations for the Day and shift use in plantations put in the execution of Pruning shears, previously used to develop mobile, pneumatic operated compact scissors have led to a maximum of 50 mm to be cut branch strength. This represents a compromise with regard to the maximum cuttable branch strength, the Sectional view and the weight of the secateurs.

Commercially available pneumatic pruning shears with push rod and guide tube bring by the large forces acting on the scissor drive and the necessary buckling relatively high masses in the system, whereby the reach of the secateurs mostly at 1.5 to 2.0 m and with additional rod extension to a maximum of 3 m is limited. The weight of the entire system is about 5 kg for a secateurs with a 3 m long handlebar. The scissor drive is based on the pneumatic cylinder, which is arranged either at the lower end of the handle or in the scissor head. In the first case, this results in disadvantages for the flexible conversion of the scissors to other ranges. In the second case, arrangement of the pneumatic cylinder in the scissor head, while it is advantageous that compressed air in the flexible tube are easily transferred. This advantage is particularly evident in comparison with an expandable rod system with a changed range length. The technical optimum and better use value are in the variant of the arrangement of the piston near the blade, but the requirement for a low weight of scissors and drive be special consideration requires.

electrical or pruning shears powered by a rechargeable battery have become professional fruit trees not enforced. These systems are used in viticulture. Technically, the scissors are designed to 30 mm and can with one by the operator Battery Belt or backpack over the entire eight-hour shift are operated. The disadvantage is the weight of the battery with about 4.5 kg and the high noise level operational. In addition to the limited capacity are the acquisition costs very high and the electric shears are, for example, in the rain only limited usable.

The available in the market pneumatic devices have a fixed and a driven cutting edge. To the force effect of the triggered Pneumatic piston over the leverage ratios to transfer to the moving edge, are long pull rods with big ones Deflection necessary or push rods, however, are at risk buckling. This usual But design way leads to the main disadvantage of unilaterally acting lateral forces. The The consequence is the strong dimensioning of the scissor head and associated weight penalties and performance degradation due to the limited lever dimensions.

in the State of the art are various pneumatic pruning shears with different Known concepts.

In the DE 203 16 206 U1 is a secateurs with telescopic rod described. The cutting edge of the scissors is driven by a compressed air piston and pressed against the fixed counter blade. The return stroke of the piston takes place after the working stroke by a spring which acts above the piston. The compressed air is routed through the telescope area to avoid loss of pressure in a spiral air hose.

adversely in this pruning shears is the low cutting force, which is the application area the pruning shears with regard to the cuttable branch thicknesses narrow limits are set. Although could through a larger cylinder generates more power and cuts thicker branches with a larger pair of scissors but according to the principle used, the weight would be of the cutting head grow so that the telescopic rod, in particular in the extended state, would not be manipulated.

The DD 276 617 A1 describes a pneumatic drive, especially for hand shears. Here, a working cylinder with several successively arranged pressure chambers is used. The force is transmitted by a coupling of the piston rods via ball joints on a single torque tube as a piston rod. The push tubes also serve to direct the compressed air from one pressure chamber to the next. These are hollow and have at the top overflow on. The pressure chambers are mounted in the handle area at the lower end of the handlebar. The power transmission to the scissors is done by means of a push rod through the interior of the handle bar.

adversely In this arrangement, the spring-driven return stroke for returning the piston to the starting position. This is due to lack of functional reliability when cutting larger branch thicknesses to go out, since it can come to jamming the scissors. moreover In the working stroke, a part of the force for tensioning the spring is needed and stands the cutting process is no longer available.

In the DE 199 23 727 C1 is a pneumatic pruner with external pneumatic cylinder described. To limit the closed position and for noise damping an adjustable rubber buffer is arranged on the linkage. However, the rubber buffer wears off and requires frequent adjustment, which is to be regarded as a disadvantage of this arrangement.

After DE 8134762 U1 An arrangement is known in which the pruner is driven by a Gelenkparallelogramm. The shears sit on a pivot pin; Intermediate links form a variable joint triangle and ensure the deflection of the movement of the piston in the cutting movement. The drive has two pistons, which are connected to each other via a piston rod. Between both pistons there is a partition with gas-tight passage through which the piston rod passes. A tension spring pulls both pistons in the starting position, alternatively, compression springs are arranged in the cylinder chambers.

Such an arrangement has the disadvantage that the pistons can not be actively withdrawn, which would be necessary in the case of a clamping blade. In addition, the construction has numerous massive parts that suggest a high weight of the pruning shears. Thus, the cylinder is firmly closed on both sides, which in the lower area for the maintenance of the cylinder according to the construction according to the DE 8134762 U1 is required. The top cover of the cylinder is essential as a guide for the piston rod. The high weight of pruning shears makes handling especially difficult when an extension in the form of a handle bar for Schneidarbei used at higher altitudes.

The FR 1534936 A describes a pneumatic scissors, in which the compressed air drive unit is arranged in close proximity to the shearing device. The pneumatic drive unit is arranged centrally and concentrically constructed, the scissors is mounted laterally thereof at the front end of the pneumatic drive unit. As a result, the compressed air drive unit is subjected to bending during operation and must be given a corresponding stability, which results in a high weight.

moreover is by the big one Diameter of the working cylinder the view on the cutting edges and the Workspace impeded.

The Object of the present invention is a pneumatic pruning shears available too put, the branches greater thickness to be able to cut at a low weight.

The Task is by a pneumatic pruner with handle bar and cutting head with shear blades solved, wherein the cutting head consists of a central guide tube and an outer, coaxial with the central guide tube arranged pneumatic cylinder is formed with annular piston. The annular Piston is as a double piston with front piston, rear piston and intermediate disc formed double acting. To is located in the pneumatic cylinder corresponding to a rear Working room and a front working room. The central guide tube The cutting head is at one end with the handlebar and the other End configured with the fork head connectable with the shear blades. Furthermore, means for fixing the pneumatic cylinder, for example in the form of a threaded portion, and means for fixing the pneumatic cylinder and the cutting disc, for example in the form of a stop provided.

To a constructive development of the invention is the front and the rear piston of the double piston by at least one two radially arranged rods existing linkage spaced apart, wherein the linkage the function of the piston rod the rear piston takes over as part of the double piston.

The linkage penetrates axially in the guide tube Fixed cutting disc during the movement of the double piston. Functionally, this must be linkage Therefore, be formed sealed to the cutting disc.

From particular advantage is the formation of a double-acting Lever kinematics with five joints for power transmission from the double piston over a thrust sleeve acting as a piston rod on the shear blades a further embodiment of the invention.

The double - acting lever kinematics and the cutting edge geometry of the Shear leaves moving toward one another act in such a way that at maximum cutting opening and the maximum branch diameter always at right angles to the branch center point acting cutting force and a drawn cut is realized.

The pneumatic according to the invention Pruning shears use a compound cylinder with centric scissors operation. Always equal parallel pull rods, which are part of both sides acting lever kinematics of the scissors system are less demanding Space and weight.

One important utility value is in addition to the power and the operating weight the cut quality. to Achievement of the "pulled Schnitt "is in the connection with the two-sided mirrored lever kinematics one Cutting edge geometry has been developed at maximum cutting edge and the nominal cutting capacity of 65 mm is always a right angle unfolds to the branch center acting cutting force. The from the pneumatic piston outgoing cutting force thus acts with minimal losses and the Cut becomes evenly smooth.

Especially It is advantageous that the central guide tube is designed in the interior as a pressure buffer chamber and to the feeder the compressed air to the Arbeitshubräumen the pneumatic cylinder connecting holes are provided.

The Design of the sliding sleeve As a coaxial cylinder to the central guide tube is particularly cost-effective and structurally simple and robust in design.

A Further development of the pneumatic according to the invention Pruning shears, between the rear piston and the cutting disc a Rückbewegungshubraum in the pneumatic cylinder for the active return stroke for pneumatic opening the shearer blades and an associated one Connecting hole in the central guide tube with means for Compressed air supply for the return stroke is provided leads to the additional Advantage that the return stroke actively executable is. This is especially helpful in jamming the shear blades.

The design of an effective, wear-free cushioning can be realized in principle in two different ways, on the one hand by elastically acting damping elements, which are installed in the piston or in the system of lever kinematics, without causing a wear-free Operation is possible. On the other hand, the particularly advantageous solution according to the invention has been found which consists of a control system which allows the construction of an air cushion before reaching the piston end position.

According to one advantageous embodiment of the invention are in front of the end position of Piston both in Rückhubstellung as well as in working position on the outer side of the central guide tube damping slots for pneumatic motion damping via air cushions intended.

The central guide tube is because of its functional integration and the associated mechanical to be processed functional surfaces as well as tribological considerations made of metal. In In a preferred embodiment, it is made of aluminum.

to Task-related weight reduction the pruner according to the invention the pneumatic cylinder is made of a lightweight composite material, in an alternative embodiment also of aluminum or other suitable materials.

To the concept of the invention receives the pneumatic pruner as drive energy compressed air. These is supplied with a flexible lightweight tube and passed over by hand Control valve with pressure relief valve and compressed air hose on Handle controlled. The cutting system according to the invention realized the drawn section and acts with regard to the direction of the force of cutting forces compensating, outward neutral and therefore closely related. An overhead pneumatic Telescopic working cylinder, according to a preferred embodiment made of fiber-reinforced composite material is crafted, acts differentiated and is in the development of forces tuned to be the highest Force development at 40% cutting opening at the moment of the largest cutting force requirement is unfolded.

• • Pneumatikzylinder in der bevorzugten Ausführungsform als GFK-Kompaktzylinder mit Zentralführungsstange;
• • Schubhülse;
• • beidseitig wirkende Hebelkinematik mit Übertragungshebeln;
• • Gabelkopf mit Scheren- bzw. Messerhebel;
• • Steuereinheit mit Druckbegrenzungsventil und Druckluftschlauch.

The pneumatic pruner according to the invention consists of the following main components:

• • Pneumatic cylinder in the preferred embodiment as a GFK compact cylinder with central guide rod;
• • push sleeve;
• • Bilateral lever kinematics with transmission levers;
• • Clevis with scissors or knife lever;
• • Control unit with pressure relief valve and compressed air hose.

By the use of lightweight composite materials, such as carbon fiber or fiberglass-reinforced Plastic and aluminum liners, it is at full use and load characteristics possible, a powerful and especially lightweight device as standard for disposal to deliver.

there comes a completely new kinematic operating principle for the two cutting modules for one so far only by sawing implemented application area. Furthermore, a two-stage Pneumatic drive and other device components implemented in consistent plastic composite lightweight construction.

Of the Compact cylinder made of glass fiber reinforced plastic (GRP) can as a composite construction using a thin aluminum sheet inliner or wear-resistant Plastic are made. The stiffness and strength arises through the GRP winding composite, whereby further technological construction and manufacturing variants can be used.

For the piston with push sleeve alternative materials can be used, if necessary material combinations, the lightweight properties with punctual load requirements connect.

As an alternative embodiment of the cutting edges high-strength sheet materials are used, taking into account maximum allowable deformation limits and wear on the cutting limbs, which already have the ultimate strength of about 1,000 N / mm ² . As an advantageous development, the components are annealed after mechanical processing.

at the design of the cutting tools is in an advantageous embodiment the by-pass principle for realized a smooth cutting result. This constructive principle is characterized in that the cutting edges simultaneously as a support with almost flat contact surfaces and as active cutting are formed. When cutting the cutting tools are flat to each other past. With the curved cutting edge design, the radius is based on the maximum branch diameter, the Fixed branch to be cut. The cutting surfaces should be considered as a prerequisite for the Compliance with a minimum cutting gap to be plane-parallel. This Principle ensures energy-saving and qualitative benefits, such as lower Cutting forces less bruising and smoother parting surfaces.

The Cutting tools are designed to be changed quickly can be nachschleifbar and re-usable without renewed surface coating. An integrated system for automatic cutting gap adjustment ensures a consistent cut surface quality on the tree.

lightweight principles also come in the development of a lighter and stiffer handlebar for use. In this case, in an advantageous embodiment a necessary bar stability by an integrated chamber or cell structure under weight criteria achieved and the inclusion of the media line allows. Handlebars different Length, in an alternative embodiment two and three meters, allow the gradual adaptation to different working heights. The Compact scissors are at 8 to 12 bar compressed air as drive medium designed. Depending on the usage concept or the requirements On-site, the medium may consist of a vehicle-mounted compressed air system, from a mobile compressor or via pressure reducer from bottles be removed. Acoustically relevant noise limits when relaxing the compressed air could arise are prevented with a valve system.

To A preferred embodiment of the invention are embodiments of the pneumatically driven base unit as a manageable short device or with an extension on 4.5 m with the correspondingly long handlebar as suitable for kroner upgraded.

To An advantageous development of the invention is the handlebar an electrically insulating rod made of glass fiber reinforced plastic for work near of power transmission lines.

To Another embodiment of the invention is a knife quick-change system used to minimize necessary service interruptions.

One Advantage of the conception according to the invention persists in that various cutting modules as essay assemblies for specific applications and be used with specific cutting geometry.

• • flexibler Einsatz im Scherverfahren je nach Holzart bis 65 mm, Schere zur Hochentastung bis 5 m Höhe;
• • Funktions- und Handhabungssicherheit im Einsatz auch bei 5 m Schnitthöhe;
• • als modifizierungsfähiges Gerät Einsatz im Plantagenobstbau, im kommunalen Baumpflegebereich sowie bei der Hochentastung in der Freileitungswartung;
• • Leichtbauweise durch Einsatz von faserverstärkten Verbundwerkstoffen im Gerätegerüst und in den Kräfteübertragungselementen;
• • mit minimiertem Einsatzgewicht geringe Handhabungsmasse im Hochleistungsbereich;
• • elektrisch isolierender Griffstab aus Glasfaser für Arbeiten nahe bei Energiefreileitungen;
• • der zweistufige Pneumatikantrieb in extra kurzer Bauweise auf der Basis eines Doppelkolbens hat nur etwa 100 mm Hubweg;
• • die Schneidenfunktionskinematik erzeugt in dem Moment, in dem der höchste Schnittkraftbedarf besteht, bei 40% der Schneidenöffnung maximale Schnittkraftentfaltung;
• • parallel wirkende Zugstangen, die Bestandteil der beidseitig wirkenden Hebelkinematik des Scherensystems sind, erfordern weniger Platz und haben ein geringeres Gewicht;
• • das Scherenfunktionsprinzip ermöglicht, dass die Schnittkräfte innerhalb des kinematischen Systems aufgenommen und damit die Biegemomente weitestgehend von der Trägerstange ferngehalten werden;
• • die Schneidengeometrie realisiert in der Verbindung mit den kinematischen Antriebsverhältnissen auch im Bereich des maximalen Schnittbereiches von 65 mm den „gezogenen Schnitt";
• • pneumatische Kompaktschere in Modulbauweise als Basisgerät bzw. als Scherenantriebsvorrichtung und Scherenaufsatz;
• • die erfindungsgemäße Baumschere verfügt über eine beidseitige Endlagendämpfung im Pneumatikzylinder;
• • ein geringer Außendurchmesser des Pneumatikzylinders lässt freie Sicht auf den Schneidenansatz zu, wenn mit der Verlängerung des Griffes gearbeitet werden muss und Sicht- sowie Gerätefunktionslinie nahe beieinander liegen.

The advantages of the device according to the invention can be summarized as follows:

• • flexible use in the shearing process, depending on the type of wood up to 65 mm, scissors for high-keying up to 5 m in height;
• • Functional and handling safety in use, even at 5 m cutting height;
• • as a modifiable device used in plantation fruit growing, in the municipal tree care sector as well as in the overhead keying in the overhead line maintenance;
• • Lightweight construction through the use of fiber-reinforced composites in the scaffold and in the force transmission elements;
• • minimized use weight low handling mass in the high performance area;
• • electrically insulating fiberglass handle for work close to overhead power lines;
• • The two-stage pneumatic actuator with extra short design based on a double piston only has a stroke of approx. 100 mm;
• • The cutting function kinematics generates maximum cutting force development at 40% of the cutting edge opening at the moment when the highest cutting force requirement is required;
• • Parallel pull rods, which are part of the bilateral lever kinematics of the scissors system, require less space and weight;
• • The scissor function principle allows the cutting forces to be absorbed within the kinematic system, thus keeping the bending moments as far as possible from the carrier bar;
• • In combination with the kinematic drive conditions, the cutting edge geometry also realizes the "drawn cut" in the area of the maximum cutting area of 65 mm;
• • compact pneumatic scissors in modular design as basic unit or as scissors drive device and scissors attachment;
• • The pruner according to the invention has a double-end cushioning in the pneumatic cylinder;
• • A small outer diameter of the pneumatic cylinder allows a clear view of the cutting edge when working with the extension of the handle and the visual and device function lines are close to each other.

Especially It should be stressed that compressed air is an energy source Leakage and safety aspects is completely harmless and almost no precautionary measures in terms of occupational safety.

Further Details, features and advantages of the invention will become apparent the following description of embodiments with reference on the associated Drawings. Show it:

1 : Cutting head in sectional view;

2 : Cutting head in plan view;

3 : central guide tube with double piston and cutting disc;

4 : central guide tube sectional view;

5 : front piston with push sleeve.

In 1 the exemplary embodiment of a cutting head according to the subject invention is shown in section. The cutting head is essentially from the central guide tube 1 , the pneumatic cylinder 2 and the clevis 9 with the blades 4 and 5 educated.

An essential element of the design is the central guide tube 1 is, which at its lower end a connecting piece 21 for the handlebar 8th with integrated connections for the compressed air supply. At the upper end of the central guide tube 1 is the clevis 9 arranged and according to the illustrated advantageous embodiment of the invention, this closes the central guide tube 1 at the upper end, by means of a thread in the central guide tube 1 screwed in and optionally gas and pressure-tight glued.

The central guide tube 1 is hollow in its interior and thereby forms a pressure buffer chamber 20 out. Thus, the pressure-tight completion of the central guide tube 1 Functionally required at the ends and the connecting piece 21 as well as the clevis 9 Be pressure tight with the central guide tube 1 connected. The pneumatic cylinder 2 is designed as a GRP cylinder and coaxial with the central guide tube 1 spaced. Between the coaxial pneumatic cylinder and the central guide tube 1 Thus, an annular gap is formed with an annular cross-section, in which the double piston is axially guided. The pneumatic cylinder 2 tapers in its lower part to a mounting area on the central guide tube 1 and is open at the top.

In the annular gap between the pneumatic cylinder 2 and the central guide tube 1 performs the double piston his working movements from bottom to top and the resetting movements from top to bottom, actively controlled by a compressed air system, from. The double piston is made up of a rear piston 11 and a front piston 10 , The pistons 10 . 11 themselves are designed as annular pistons which are connected to each other by a linkage 13 are spaced. Between the pistons 10 . 11 is a cutting disc 12 arranged and on the central guide tube 1 fixed. The linkage 13 of the double piston is through the cutting disc 12 passed through, wherein in the cutting disc 12 a seal to the linkage 13 is provided.

The linkage 13 thus fulfills the function of a piston rod of the rear piston 11 and is at the same time the connection to the front piston 10 for the training of the double piston. The front piston 10 is with a push sleeve 3 connected the movement of the double piston to the lever kinematics 6 transfers. The bilateral lever kinematics 6 is via a toggle with five joints 19 formed, which is designed such that the shear blades 4 . 5 during the movement of the push sleeve 3 to the front end of the central guide tube 1 towards each other.

The push sleeve 3 is formed according to the illustrated embodiment as a cylindrical tube and coaxial with the central guide tube 1 and slidably mounted on this stored.

The joints 19 connect the individual elements of the double-acting lever kinematics 6 and are by bolts 7 completed.

In the circular cylindrical volume between the pneumatic cylinder 2 and the central guide tube 1 are different cavities through the double piston and the cutting disc 12 educated.

Between the rear piston 11 and the connecting portion of the tapered pneumatic cylinder 2 as well as the central guide tube 1 is with a small dead volume of the rear power stroke 22 educated. This rear power stroke 22 is through a connecting hole (rear working stroke) 15 in the central guide tube 1 from the pressure buffer chamber 20 pressurized with compressed air. Another working stroke, the front working stroke 23 , is between the front piston 10 and the cutting disc 12 educated. This upper working stroke is also with the pressure buffer chamber 20 of the central guide tube 1 through a connecting bore (front working stroke) 14 for compressed air supply in connection.

Between the cutting disc 12 and the rear piston 11 is the return stroke 24 educated. The return movement hub 24 is via a connection hole (Rückbewegungshubraum) 16 acted upon by a separate compressed air supply. The separate compressed air supply is from the connection bore (Rückbewegungshubraum) 16 over one in the pressure buffer chamber 20 laid hose to the lower end of the central guide tube 1 guided and there in the connecting piece 21 involved.

The connecting piece 21 has two compressed air connections. A compressed air connection serves to supply the pressure buffer chamber 20 with compressed air for the working movement and the second compressed air connection is used to supply the Rückbewegungshubraums 24 with compressed air for active return movement of the double piston and the associated opening of the shear blades 4 and 5 , Particularly advantageous in the illustrated embodiment of the invention is that as a means for compressed air supply for the return stroke 17 a hose from the connecting piece 21 is provided for connecting bore to Rückbewegungshubraum. This is particularly advantageous because in this way all compressed air Supply lines mechanically protected inside the central guide tube 1 and after transition at the connecting piece 21 inside the handlebar 8th extend to the operating area with the required pneumatic valves and the pneumatic supply.

Likewise, the pneumatic hose runs for the compressed air of the pressure buffer chamber 20 from the connecting piece 21 inside the handlebar 8th ,

In the area of the rear or lower end position of the front piston 10 are on the outside area of the central guide tube 1 damping slots 18 provided for damping movement of the double piston when reaching the end position, both the working and the return stroke.

Just before reaching or striking the front piston 10 or the rear piston 11 on the cutting disc 12 is closed in the vented working or Rückhubraum the exhaust hole. Due to the now only very small outflow cross-section builds on the still ongoing movement of the piston, an air cushion, which slows down the forward and backward movement.

In 2 the cutting head is shown in plan view. At its lower or rear end is the connection piece 21 at the central guide tube 1 , Follow the course of the central guide tube 1 up, then closes the pneumatic cylinder 2 which, by means of a cup-like taper in the lower area with the central guide tube 1 connected and upwards, however, is designed to be open.

The bilateral lever kinematics 6 is, as far as visible, with the two front joints 19 and the associated levers and clevis 9 with shear blade (knife) 4 and shear blade (counter blade) 5 finally shown the cutting head. The clevis 9 closes the central guide tube 1 with the pressure buffer chamber 20 pressure tight at the distal end.

Another view of the embodiment is in 3 shown. The central guide tube 1 is without the pneumatic cylinder 2 imaged, creating the double piston with the cutting disc 12 and the push sleeve 3 with the complete bilateral lever kinematics 6 and the clevis 9 are shown from the side.

The connecting piece 21 closes the central guide tube 1 with the pressure buffer chamber 20 pneumatically sealed at its lower and rear ends. The double piston consists of rear piston 11 and front piston 10 which through the linkage 13 spaced apart from each other. The double piston moves axially on the central guide tube 1 , where the linkage 13 of the double piston through recesses in the cutting disc 12 slides. The recesses are sealed, since displacements with different pressures between the rear piston 11 and the cutting disc 12 and the cutting disc 12 and the front piston 10 are formed. The double piston is with its front piston 10 on the one hand with the cylindrical sliding sleeve 3 firmly connected and on the other side, the push sleeve 3 two joints 19 on, over which the bilateral lever kinematics 6 with the sliding sleeve 3 connected is. Upon movement of the double piston to the upper or front end of the central guide tube 1 becomes the push sleeve 3 thus moved up and the double-acting lever kinematics 6 causes the working or cutting or shearing movement of the blade (knife) 4 to the shear blade (counter blade) 5 towards, which is around the distal joint 19 of the fork head move towards each other.

In 4 is the central guide tube 1 shown in section. It will be the connecting piece 21 for the pneumatic systems for working stroke and return stroke at one end of the central guide tube 1 shown and in this representation, it is very clear that a compressed air connection of the connecting piece 21 direct compressed air into the pressure buffer chamber 20 of the central guide tube 1 while the second compressed air connection via a hose as means for compressed air supply for the return stroke 17 the compressed air through the pressure buffer chamber 20 passes through a deflection piece and the connection bore (Rückbewegungshubraum) 16 in the central guide tube 1 the compressed air for the return movement of the shear blades 4 . 5 to provide. Furthermore, the connection holes (front working stroke) 14 and (rear working stroke) 15 shown for the front and rear working stroke in the cutting motion, through which the compressed air from the pressure buffer chamber 20 in the central guide tube 1 be routed to the respective workrooms.

In 5 is the front piston 10 in its connection with the sliding sleeve 3 and the connections for the joints 19 shown in section. The circular cylindrical front piston 10 is on the equally cylindrical sliding sleeve 3 fixed in a form-fitting manner.

The double piston is from the rear piston 11 and the front piston 10 educated. Through the linkage 13 are both pistons 10 . 11 rigidly connected. The double piston transmits the movement by means of the push sleeve 3 on the at the joints 19 attached bilateral lever kinematics and on this on the clevis 9 with the blades 4 and 5 ,

• – Die Scherblätter 4 und 5 befinden sich in geöffneter Stellung.
• – Über geeignete Betätigungseinrichtungen wird Druckluft über den Anschlussstutzen 21 in die Druckpufferkammer 20 im zentralen Führungsrohr 1 eingeleitet.
• – Zugleich wird der Rückbewegungshubraum 24 gegen die Umgebung entlüftet.
• – Die Druckluft gelangt über die Verbindungsbohrungen (vorderer Arbeitshubraum) 14 und (hinterer Arbeitshubraum) 15 in den hinteren und vorderen Arbeitshubraum 22, 23. Die Arbeitshubräume 22, 23 sind in dem Ringspalt zwischen dem Pneumatikzylinder und dem zentralen Führungsrohr 1 ausgebildet.
• – Der Doppelkolben aus hinterem Kolben 11 und vorderem Kolben 10 wird nach oben bzw. zum vorderen Ende des Pneumatikzylinders 2 durch die Expansion der Druckluft in den Arbeitsräumen 22, 23 bewegt.
• – Durch die Bewegung des Doppelkolbens wird die sich daran anschließende Schubhülse 3 mitbewegt, an deren oberem Ende die beidseitig wirkende Hebelkinematik 6 über Gelenke 19 bewegt wird.
• – Das Scherblatt (Messer) 4 bewegt sich auf das Scherblatt (Gegenschneide) 5 zu und ein dazwischen liegender Ast wird zerschnitten.
• – Kurz vor Schnittende bzw. dem Anschlagen der hinteren Kolbenscheibe an der Trennscheibe wird durch den Dämpfungsschlitz 18 im Rückbewegungshubraum 24 ein Luftpolster aufgebaut, welches aufgrund des geringen Drosselquerschnitts nur langsam entweicht.
• – Nach der Beendigung des Schnittes wird Druckluft über das Steuerventil zum zweiten Druckluftanschluss im Anschlussstutzen 21 und in die Mittel zur Druckluftzuführung für den Rückhub 17, beispielsweise einen Schlauch, geleitet.
• – Die Druckluft wird im Schlauch durch die Druckpufferkammer 20 hindurchgeleitet und schließlich über die Verbindungsbohrung (Rückbewegungshubraum) 16 für den Rückbewegungshubraum 24 in diesen eingeleitet. Dabei wird der Doppelkolben aus seiner vorderen und oberen Stellung in die hintere und untere Stellung bewegt und die beidseitig wirkende Hebelkinematik 6 öffnet sich aktiv gesteuert durch die Druckluftzuführung in den Rückbewegungshubraum 24.
• – Zum Ende des Rückhubs hin wird die Bewegung des Doppelkolbens mittels der Dämpfungsschlitze 18 zum Druckausgleich gebremst, um einen harten Anschlag der Schubhülse 3 an der Trennscheibe 12 zu verhindern.

The sequence of a cut with the pneumatic pruner is briefly outlined in the following steps:

• - The shear blades 4 and 5 are in open position.
• - Compressed air is supplied via the connecting piece via suitable actuating devices 21 in the pressure buffer chamber 20 in the central guide tube 1 initiated.
• - At the same time the Rückbewegungshubraum 24 vented against the environment.
• - The compressed air passes through the connecting bores (front working stroke) 14 and (rear working stroke) 15 in the rear and front power stroke 22 . 23 , The workhouses 22 . 23 are in the annular gap between the pneumatic cylinder and the central guide tube 1 educated.
• - The double piston from the rear piston 11 and front piston 10 goes up or to the front end of the pneumatic cylinder 2 by expanding the compressed air in the work spaces 22 . 23 emotional.
• - The movement of the double piston is the adjoining thrust sleeve 3 moved, at the upper end of the two-sided lever kinematics 6 over joints 19 is moved.
• - The shear blade (knife) 4 moves on the shear blade (counter blade) 5 to and an intervening branch is cut.
• - Shortly before cutting end or striking the rear piston disc on the cutting disc is through the damping slot 18 in the return movement hub 24 built an air cushion, which escapes only slowly due to the small throttle cross-section.
• - After completing the cut, compressed air is supplied via the control valve to the second compressed air connection in the connecting piece 21 and in the means for compressed air supply for the return stroke 17 , For example, a hose, passed.
• - The compressed air is in the hose through the pressure buffer chamber 20 passed through and finally via the connection bore (Rückbewegungshubraum) 16 for the Rückbewegungshubraum 24 initiated in these. In this case, the double piston is moved from its front and top position to the rear and lower positions and the double-acting lever kinematics 6 opens actively controlled by the compressed air supply in the Rückbewegungshubraum 24 ,
• - Towards the end of the return stroke, the movement of the double piston by means of the damping slots 18 braked to equalize the pressure to a hard stop of the sliding sleeve 3 on the cutting disc 12 to prevent.

1

central guide tube

2

pneumatic cylinder

3

push sleeve

4

Scherblatt (Knife)

5

Scherblatt (Bedknife)

6

lever kinematics (double-acting)

7

bolt

8th

Grab bars

9

clevis

10

front piston

11

rear piston

12

cutting wheel

13

linkage

14

connecting bore (front working stroke)

15

connecting bore (rear working stroke)

16

connecting bore (Return movement displacement)

17

medium for compressed air supply for the return stroke

18

damping slot

19

joint

20

Pressure buffer chamber

21

spigot

22

rear working stroke

23

front working stroke

24

Return movement displacement

Claims (10)

Pneumatic secateurs with handle bar and cutting head with shear blades ( 4 . 5 ), characterized in that - the cutting head consists of a central guide tube ( 1 ) and an outer, coaxial with the central guide tube ( 1 ) arranged pneumatic cylinder ( 2 ) is formed with an annular piston and - that the annular piston as a double piston with front piston ( 10 ), rear piston ( 11 ) and intermediate separating disc ( 12 ) is double-acting and in the pneumatic cylinder ( 2 ) corresponding to a rear working stroke ( 22 ) and a front working stroke ( 23 ) is formed and - that the central guide tube ( 1 ) of the cutting head at one end with the handle bar ( 8th ) and at the other end with a clevis ( 9 ) with the shear blades ( 4 . 5 ) is configured connectable and - that further means for fixing the pneumatic cylinder ( 2 ) and the cutting disc ( 12 ) are provided. Pneumatic pruner according to claim 1, characterized in that the front and rear pistons ( 10 . 11 ) of the double piston by a rod consisting of at least two radially arranged rods ( 13 ) spaced apart are. Pneumatic pruner according to claim 2, characterized in that the linkage ( 13 ) axially the cutting disc ( 12 ) is formed penetrating movable and sealed. Pneumatic pruner according to one of claims 1 to 3, characterized in that a sliding sleeve ( 3 ) and a double-acting lever kinematics ( 6 ) with five joints ( 19 ) for transmitting power from the double piston to the shear blades ( 4 . 5 ) are provided. Pneumatic secateurs according to claim 4, characterized in that the double-acting lever kinematics ( 6 ) and the cutting geometry of the shear blades ( 4 . 5 ) cooperate in such a way that at maximum edge opening and the maximum branch diameter always acting at right angles to the branch center cutting force and a drawn section is realized. Pneumatic pruner according to one of claims 1 to 5, characterized in that the central guide tube ( 1 ) in the interior as a pressure buffer chamber ( 20 ) is executed and for supplying the compressed air to the Arbeitsshubräumen ( 22 . 23 ) of the pneumatic cylinder ( 2 ) the connection bore (front working stroke) ( 14 ) and the connection bore (rear working stroke) ( 15 ) are provided. Pneumatic pruner according to one of claims 1 to 6, characterized in that the thrust sleeve ( 3 ) as a coaxial cylinder to the central guide tube ( 1 ) is trained. Pneumatic pruner according to one of claims 1 to 7, characterized in that between the rear piston ( 11 ) and the cutting disc ( 12 ) a Rückbewegungshubraum ( 24 ) in the pneumatic cylinder ( 2 ) for the active return stroke for the pneumatic opening of the shear blades ( 4 . 5 ) and an associated connection bore (return stroke) ( 16 ) in the central guide tube ( 1 ) are provided with means for supplying compressed air for the return stroke. Pneumatic pruner according to one of claims 1 to 8, characterized in that before each end position of the piston ( 10 . 11 ) on the outer side of the central guide tube ( 1 ) Attenuation slots ( 18 ) are provided for pneumatic motion damping over air cushion. Pneumatic pruner according to one of claims 1 to 9, characterized in that the pneumatic cylinder ( 2 ) consists of a lightweight composite material.