EP0719201A1 - Systeme hydraulique - Google Patents

Systeme hydraulique

Info

Publication number
EP0719201A1
EP0719201A1 EP94927887A EP94927887A EP0719201A1 EP 0719201 A1 EP0719201 A1 EP 0719201A1 EP 94927887 A EP94927887 A EP 94927887A EP 94927887 A EP94927887 A EP 94927887A EP 0719201 A1 EP0719201 A1 EP 0719201A1
Authority
EP
European Patent Office
Prior art keywords
hydraulic
valve
port
pressure
oil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94927887A
Other languages
German (de)
English (en)
Inventor
Jerzy Janczak
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Husqvarna AB
Original Assignee
Husqvarna AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Husqvarna AB filed Critical Husqvarna AB
Publication of EP0719201A1 publication Critical patent/EP0719201A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G3/00—Cutting implements specially adapted for horticultural purposes; Delimbing standing trees
    • A01G3/02—Secateurs; Flower or fruit shears
    • A01G3/033—Secateurs; Flower or fruit shears having motor-driven blades
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
    • B23D15/00—Shearing machines or shearing devices cutting by blades which move parallel to themselves
    • B23D15/12—Shearing machines or shearing devices cutting by blades which move parallel to themselves characterised by drives or gearings therefor
    • B23D15/14—Shearing machines or shearing devices cutting by blades which move parallel to themselves characterised by drives or gearings therefor actuated by fluid or gas pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23D—PLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
    • B23D29/00—Hand-held metal-shearing or metal-cutting devices
    • B23D29/002—Hand-held metal-shearing or metal-cutting devices for cutting wire or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • B25F5/005—Hydraulic driving means

Definitions

  • the present invention relates to a hydraulic system for operating a working device, such as a hand-held tool, which is located at a distance from a hydraulic-oil pressure source and which is driven by a single-acting hydraulic cylinder, wherein the hydraulic system in order to enable the hydraulic cylinder of the working device to be connected to the system by means of a single supply line, includes a valve which is connected to the pressure source which has an associated tank.
  • the valve includes a valve chamber which has a pressure port for receiving hydraulic oil from the pressure source and a return port for delivering return oil to the tank, and a working port for delivering hydraulic oil to and receiving return oil from the hydraulic cylinder through the medium of a common pressure-and-return line connected between the valve and the cylinder.
  • Hydraulic systems have long been used in the performance of many different types of working and maneuvering operations, and are also being used to an ever increasing extent in the operation of manual tools of different kinds. It is important in this latter case that the equipment can be used easily, i.e. that the working movements are guided by simple means and that the tool has good maneuverability. It is particularly important in the case of tools fitted to long shafts or handles that the handle can be moved easily in the required manner and that the working movements of the tool can be controlled and guided without the tool operator needing to release his hold on the tool handle. Furthermore, it is necessary for the hydraulic-oil delivery line between the handle and the hydraulic-oil pressure source to be simple and constructed so as to minimize the risk of injury from the high oil pressure.
  • CH-A5-330590 describes a hydraulic system which includes several moveable parts and which requires the simultaneous activation of two different devices in order to achieve the desired function.
  • the main object of the present invention is to provide a simple hydraulic system which can be used with hand-held tools, including tools fitted on long handles, and which will enable the tool to be maneuvered with one hand and which includes the least possible number of parts, particularly moveable parts and sealing surfaces and lead-throughs or throughlets.
  • a hydraulic system of the kind defined in the first paragraph is mainly characterized in that the valve is adapted to be controlled automatically by the inlet pressure that acts on a pressure-controlled valve slide which is mounted in the valve chamber and which can be adjust ⁇ ed positionally against the action of a biassing spring, such that when in a rest position, i.e. at low inlet pressures, the slide will hold the pressure port closed while the working port communicates with the return port, whereas at higher inlet pressures the position of the valve slide is adjusted against the spring tension to a position in which the working port communicates with the pressure port and the return port is closed.
  • Such a hydraulic system will enable, for instance, a handle- mounted tool to be connected to the pressure source by means of one single line which will delivers high-pressure oil only during the actual working stage.
  • the tool can also be con- trolled by a switching on and off a hydraulic pump which thus need only generate a high pressure during the actual working stage. This lowers the extent to which the oil is heated and reduces the need for additional tank volume for the purpose of cooling the oil.
  • the hydraulic system obviates the need of a complicated, heavy valve assembly for the switching of a high oil pressure.
  • the hydraulic pump may be switched on and off with the aid of a speed-dependant coupling, conveniently a so-called centrifu ⁇ gal clutch, connected between the pump and the pump drive motor.
  • the pump may also be switched on and off by control- ling the speed of the drive motor, which in the case of an internal combustion motor, or engine, may be effected with the aid of a gas throttle mounted on an operating shaft.
  • the pressure dependant valve may conveniently be mounted directly on the hydraulic pump with the pressure port connected to the pump outlet and the return port connected to the tank to which the pump is coupled. This provides a very compact unit.
  • valve pressure port is suitably in the form of a hollow screw which can be screwed firmly into the pump outlet so as to firmly attach the valve to the pump while providing a direct flow connection between the pressure port and the pump outlet.
  • An extremely compact unit can be obtained by immersing the pump and the valve in the oil contained in the tank, the tank preferably being fully closed and provided with a filling opening located in a position which will prevent the tank from being filled completely.
  • Such a compact unit is very light in weight and can be readily handled by the tool operator.
  • the unit also has only one external hose connection, which results in a readily handled and flexible unit.
  • FIG 2 illustrates the drive motor and hydraulic pump used in the hydraulic system shown in Figure 1;
  • Figure 3 is a view corresponding to the view of Figure 2 but with the end-connection of the oil tank removed;
  • Figure 4 is a partially sectioned side-view of part of the equipment shown in Figure 2;
  • Figure 7 is a side view of the tool included in the equipment shown in Figure 1;
  • FIGS 8 and 9 are partial sectioned views of the tool illustrated in Figure 7 and show the tool in two different working stages;
  • Figures 10 and 11 illustrate the tool shown in Figure 7 from above and from beneath respectively.
  • Figures 12 and 13 illustrate fitting of a part of the tool illustrated in Figure 7.
  • Figure l illustrates a workman 1 cutting high branches from a tree with the aid of a pruning tool 3 fitted to a long handle 2.
  • the workman carries an internal combustion engine 4 and a hydraulic pump fitted thereto, for operating the tool.
  • the hydraulic pump is connected to the tool 3 by means of a single hose or delivery line 5, the the majority of which extends inside the handle 2, the tool being driven by a single-acting hydraulic cylinder in which the piston is returned by a spring.
  • the workman is able to adjust the engine or motor speed by means of a throttle control 6 which is connected to the engine 4 by a throttle cable 7.
  • Connected between the engine output shaft and the hydraulic pump is a speed-dependent coupling which will ensure that the pump is not activated until a predetermined speed is reached.
  • the workman 1 is thus able to control the working strokes of the tool 3 with the aid of the throttle control 6.
  • valve 17 (see Figures 5 and 6) being mounted directly on the pump 10 by means of a hollow screw 21, which is screwed directly into the pump outlet.
  • the screw 21 thus functions as a valve mounting device and also as an inlet port 22 to the valve chamber 23, in which a slide 24 can be moved against the action of a biassing spring 25.
  • the valve chamber 23 is also provided with the return port 19 and the working port 26 to which the connector nipple 18 of the line 5 is connected.
  • the system works as follows: when the engine 4 runs at a speed which is below the speed at which the centrifugal clutch 12 is activated, the pump 10 will be at rest. The valve slide 24 will then be located in its rest position, shown in Figure 5, in the absence of high pressure on the port 22. The working port 26 is therewith connected directly to the return port 19 via the valve chamber 23, which means that the system is essentially pressureless, wherein the tool 3 is held in its starting position by a return spring acting on the piston of an associated cylinder device.
  • valve 17 mounted on the pump 10 provides a very compact construction and eliminates the need for filters and like devices, since the entire unit is encapsula- ted and immersed in the oil. The requirement of only one single lead through to an external line also minimizes the risk of leakage.
  • the valve 17 can be replaced with a separate valve the pressure port and return port of which can be connected to a hydraulic pump and to an associated tank respectively by means of conventional lines, while connecting the working port to the tool concerned by means of one single line in the aforedescribed manner.
  • Figure 7 is a side view of the tool 3 shown in Figure 1 when used as a pruning tool.
  • the tool includes a reciprocatingly moveable knife 31 which coacts with a pad 33 fitted to a fixed anvil 32, the pad 33 being made of a softer material than the knife so as to enable thin fibers to be severed.
  • Figure 8 shows the cylinder in a pressureless state, with a branch 36 located between the knife 31 and the pad 33.
  • Figure 9 illustrates the tool at the end of a working stroke, wherewith hydraulic oil has moved the piston 35 so as to press the knife 31 against the pad 33 while severing the branch 36.
  • energy has been stored in the return spring 37 mounted between the cylinder housing 34 and the piston 35, this spring drawing the knife back to its starting position in preparation for the next working operation, when the hydraulic pressure falls.
  • the knife 31 is pivotally attached to the top of the piston 35 by means of a hinge pin 28.
  • the hinge pin 28 fits relatively loosely into a corresponding hole in the piston, so that force transmission from the piston to the knife 31 will take place essentially through the medium of mutually coacting surfaces 37 on the top of the piston and on the knife.
  • the knife 31 is restrained against vertical movement in the channel with the aid of two pins 41, 42 which pass through corresponding holes in the knife 31 and which are guided in longitudinally extending grooves 43, 44 provided in respective sidepieces 38, 39.
  • the device can also be used as a forest clearing or forest cleaning tool, a tree delimbing tool or for similar work. Both the knife and the anvil can be replaced with other tool-parts for carrying out other types of work.
  • inventive hydraulic system can be used in many other contexts irrespective of the construction of the tool. Because the system uses a single-acting hydraulic cylinder it must be seen that means are provided for returning the piston. This can be achieved with the aid of a spring force, as shown, or by some other returning force, such as the force of gravity. The piston may also be returned manually. As will be understood, the hydraulic system may also be used in conjunction with maneuvering and operating devices and like devices in addition to the tool. It will also be understood that the afore described and illus ⁇ trated exemplifying embodiment of an inventive hydraulic syst ⁇ em can be modified in several ways within the scope of the following claims.
  • the hydraulic pump can be driven by some other form of motor, for instance an electric motor, or the hydraulic pressure can be obtained through the medium of some other activatable and deactivatable pressure source.
  • the pump or valve can be enclosed in the tank, but may be separated therefrom in a conventional manner.
  • the valve may also be integral with the pump.
  • the drive unit is shown to be carried by means of a harness it will be understood that the unit may be moved around in some other way, for instance hanging from a raisable and lowerable working platform.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Ecology (AREA)
  • Forests & Forestry (AREA)
  • Environmental Sciences (AREA)
  • Fluid-Pressure Circuits (AREA)

Abstract

L'invention concerne un système hydraulique destiné à commander un dispositif de travail, tel qu'un outil à main, à une certaine distance d'une source de pression d'huile hydraulique, dans lequel le dispositif de travail est entraîné au moyen d'un cylindre hydraulique à simple effet. Afin de permettre la connexion du cylindre hydraulique au moyen d'un seul conduit, le système comprend une soupape (17) reliée à la source de pression (10), avec un réservoir associé (8), et présentant un orifice de pression destiné à recevoir de l'huile hydraulique de la source de pression (10), ainsi qu'un orifice de retour destiné à renvoyer l'huile au réservoir (8), et un orifice de service destiné à amener l'huile hydraulique au cylindre hydraulique et à recevoir l'huile de retour de ce dernier par l'intermédiaire d'un seul conduit commun de pression et retour reliant la soupape et le cylindre. La soupape (17) est adaptée pour être commandée par la pression d'admission agissant sur une coulisse de soupape dont on peut régler la position contre la force de tension d'un ressort, de manière que lorsque la coulisse de soupape se trouve en position de repos, c'est-à-dire à une pression de faible admission, l'orifice de service communique avec l'orifice de retour, tandis que lorsque la pression d'admission est diminuée la position de la coulisse est réglée contre l'action de force de sollicitation d'un ressort, de manière que l'orifice de service communique avec l'orifice de pression. Cet agencement permet de commander le cylindre hydraulique à l'aide d'un seul conduit (6), et de le réguler par la pression appliquée sur la soupape (17).
EP94927887A 1993-09-16 1994-09-05 Systeme hydraulique Withdrawn EP0719201A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9303017 1993-09-16
SE9303017A SE501941C2 (sv) 1993-09-16 1993-09-16 Hydraulsystem för drift av ett arbetsorgan
PCT/SE1994/000818 WO1995007801A1 (fr) 1993-09-16 1994-09-05 Systeme hydraulique

Publications (1)

Publication Number Publication Date
EP0719201A1 true EP0719201A1 (fr) 1996-07-03

Family

ID=20391113

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94927887A Withdrawn EP0719201A1 (fr) 1993-09-16 1994-09-05 Systeme hydraulique

Country Status (5)

Country Link
EP (1) EP0719201A1 (fr)
AU (1) AU7712494A (fr)
SE (1) SE501941C2 (fr)
WO (1) WO1995007801A1 (fr)
ZA (1) ZA947108B (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2737078B1 (fr) * 1995-07-24 1998-01-02 Daunot Daniel Elagueur portatif hydraulique
US20110194952A1 (en) * 2007-12-19 2011-08-11 Kiviahde Mark M Effort reducing start mechanism for hydraulically propelled vehicles
JP5884669B2 (ja) * 2012-07-24 2016-03-15 日立工機株式会社 携帯型作業機
GB2520045A (en) * 2013-11-07 2015-05-13 Univ Cape Town Hydraulic pruning shears

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH330590A (de) * 1955-03-12 1958-06-15 Brauchli Oskar Einspannvorrichtung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9507801A1 *

Also Published As

Publication number Publication date
SE501941C2 (sv) 1995-06-26
ZA947108B (en) 1995-05-15
WO1995007801A1 (fr) 1995-03-23
SE9303017L (sv) 1995-03-17
AU7712494A (en) 1995-04-03
SE9303017D0 (sv) 1993-09-16

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