EP0292752B1 - Hydraulically impulsed screwdriver - Google Patents

Hydraulically impulsed screwdriver Download PDF

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Publication number
EP0292752B1
EP0292752B1 EP88107194A EP88107194A EP0292752B1 EP 0292752 B1 EP0292752 B1 EP 0292752B1 EP 88107194 A EP88107194 A EP 88107194A EP 88107194 A EP88107194 A EP 88107194A EP 0292752 B1 EP0292752 B1 EP 0292752B1
Authority
EP
European Patent Office
Prior art keywords
cylinder
bore
valve
output shaft
screwdriver
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.)
Expired - Lifetime
Application number
EP88107194A
Other languages
German (de)
French (fr)
Other versions
EP0292752A2 (en
EP0292752A3 (en
Inventor
Heinz Gerhard Anders
Konrad Karl Kettner
Eugen Mattheiss
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.)
Deutsche Gardner Denver GmbH
Original Assignee
Gardner Denver Deutschland GmbH
Deutsche Gardner Denver GmbH
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Publication date
Application filed by Gardner Denver Deutschland GmbH, Deutsche Gardner Denver GmbH filed Critical Gardner Denver Deutschland GmbH
Publication of EP0292752A2 publication Critical patent/EP0292752A2/en
Publication of EP0292752A3 publication Critical patent/EP0292752A3/en
Application granted granted Critical
Publication of EP0292752B1 publication Critical patent/EP0292752B1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B23/00—Details of, or accessories for, spanners, wrenches, screwdrivers
    • B25B23/14—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers
    • B25B23/145—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers
    • B25B23/1453—Arrangement of torque limiters or torque indicators in wrenches or screwdrivers specially adapted for fluid operated wrenches or screwdrivers for impact wrenches or screwdrivers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B21/00—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
    • B25B21/02—Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose with means for imparting impact to screwdriver blade or nut socket

Definitions

  • the invention relates to a hydro impulse wrench according to the preamble of claim 1, cf. e.g. EP-A-0 070 325.
  • the trigger piston is mounted in a central bore of the drive shaft.
  • the hole is designed as a blind hole.
  • the actuating rod is acted upon by an externally adjustable compression spring.
  • the hydraulic pressure acting on the control rod must overcome the spring force in order to actuate the switch-off device.
  • a pressure relief valve between the cylinder chamber and the pressure chamber is not provided.
  • the invention has for its object to design a generic hydraulic impulse wrench in such a way that with a structurally simple structure of the pressure relief valve, an adjustment of the torque is possible quickly and easily.
  • the object is achieved according to the characterizing features of claim 1. Due to the structural arrangement of the pressure relief valve in the central through hole, simple and inexpensive manufacture is ensured.
  • the adjusting screw is screwed into the end of the bore facing the screwdriver head and is therefore accessible axially from the free end face of the drive shaft. The adjusting screw can therefore be easily reached, so that the shutdown torque can be set quickly.
  • the constructive design ensures that the compressed air motor of the screwdriver is always switched off according to the set torque, with premature termination of the screwing process being reliably avoided.
  • the hydraulic impulse wrench has a housing 1 with a handle 2.
  • a compressed air motor 3 and a striking mechanism 4 are accommodated in the housing 1.
  • a switch 5 is mounted in the handle 2, with which a toggle valve 6 can be actuated. It lies in a compressed air supply 7 in the handle 2. It has a compressed air connection (not shown) in a known manner.
  • the compressed air supply 7 opens into a compressed air chamber 8 in the housing 1, which can be closed against the compressed air motor 3 by a shut-off valve 10 which is axially displaceable on a motor shaft 9.
  • the shut-off valve 10 can be displaced into its closed position against the force of a compression spring 11 surrounding the motor shaft 9.
  • the motor shaft 9 is rotatably mounted in the housing 1 via two roller bearings 12 and 13.
  • a sleeve-shaped end part 15 of a striking mechanism cover 14 of the striking mechanism 4 is seated on the motor shaft 9 in a rotationally fixed manner connected. It is mounted with a sleeve-shaped end part 18 on an output shaft 19, on which the end part 15 of the striking mechanism cover 14 is also mounted.
  • the output shaft 19 ends at a short distance from the motor shaft 9.
  • the two striking mechanism covers 14, 17 and the cylinder part 16 are surrounded by a cylindrical holding part 20 which overlaps the striking mechanism cover 17 at the radially outer edge with a radially inwardly directed collar 21 and has a recess 22 at the opposite end, into which a clamping ring 23 is screwed which the striking mechanism cover 14, 17 and the cylinder part 16 are braced against the collar 21 and against each other.
  • the striking mechanism covers 14 and 17 and the cylinder part 16 delimit a cylinder space 24 (FIG. 2) which is provided eccentrically in the cylinder of the striking mechanism 4 formed by the striking mechanism covers 14, 17 and the cylinder part 16.
  • the output shaft 19 passes through this cylinder space 24 and is arranged eccentrically with respect to the axis of this cylinder space 24.
  • the output shaft 19 is formed in the area within the cylinder space 24 as a striking anvil, which has the shape shown in FIGS. 2 and 4. In the area outside the cylinder space 24, the output shaft is cylindrical.
  • the output shaft 19 has a recess 25 within the cylinder space 24 (FIG. 2), which extends over the length of the cylinder space 24 and in which a lamella 26 is accommodated in a radially displaceable manner.
  • compression springs 27 (FIG. 1) which press the lamella 26 radially outward against the inner wall 28 (FIG. 2) of the cylinder part 16.
  • the compression springs 27 have one end in recesses 29 in the lamella 26.
  • the cylinder part 16 is surrounded by the housing 1 to form an annular gap 30.
  • the output shaft 19 is rotatably mounted in the housing 1 with roller bearings 31, 32.
  • a receptacle 33 for example a chuck, for screwing tools sits on the end of the output shaft 19 protruding from the housing 1.
  • the output shaft 19 is rotatable relative to the striking mechanism covers 14, 17 and the cylinder part 16.
  • the cylinder space 24 is completely filled with pressure medium, preferably with pressure oil.
  • the switch 5 is pressed so that the toggle valve 6 reaches its open position and compressed air can reach the compressed air chamber 8 via the compressed air supply 7.
  • the shut-off valve 10 is held in its open position by a locking ball 34, which is mounted in the motor shaft 9 in a radially displaceable manner and is held in the locking position by a locking piston 35.
  • the compressed air can thus reach the compressed air motor 3 through the opened shut-off valve 10 and drive it in a known manner.
  • the motor shaft 9 of the compressed air motor 3 drives the striking mechanism covers 14 and 17 and the cylinder part 16 directly.
  • the output shaft 19 is also rotatably carried along by the pressure medium in the cylinder space 24.
  • the screwing tool inserted into the receptacle 33 is thus rotated and a screw or nut is screwed into the respective component.
  • the motor shaft 9 and the output shaft 19 rotate together.
  • the output shaft 19 experiences a counterforce.
  • the motor shaft 9 with the striking mechanism covers 14, 17 and the cylinder part 16 can be rotated with respect to the output shaft 19, the motor shaft is still rotatably driven, so that the cylinder 14, 16, 17 rotates relative to the output shaft 19.
  • two radially inwardly projecting and diametrically opposed sealing strips 36 and 37 are provided on the inner wall 28 of the cylinder part 16, which are formed in one piece with the cylinder part 16 and have an end face which acts coaxially with the cylindrical inner wall 28 and acts as a sealing surface Have 38 and 39.
  • the hydraulic medium in the cylinder chamber 24 ' is pressurized because the medium can no longer escape into the cylinder chamber 24''.
  • the pressure that builds up here is transmitted to the part of the output shaft 19 located in the cylinder space, which is then jerkily rotated in the direction of rotation of the cylinder part 16.
  • the edge 40 of the output shaft 19 is free from the sealing strip 36, so that the hydraulic medium from the cylinder chamber 24 'can get back into the cylinder chamber 24''. Since during the sealing position (Fig. 4) the hydraulic medium can not or only very slowly be displaced from the cylinder chamber 24 ', the cylinder part 16 and thus the compressed air motor 3 is braked.
  • the screwdriver is provided with a torque setting device 41 (FIG. 1) with which, depending on the hydraulic pressure in the cylinder space 24, the screwdriver is automatically switched off correctly when the predetermined limit torque is reached.
  • the torque setting device 41 has an adjusting screw 42 which is screwed into a coaxial threaded bore 43 in the output shaft 19. As a result of this arrangement, the adjusting screw 42 is easily accessible for setting the switch-off time of the screwdriver.
  • the adjusting screw 42 extends with a thread-free section into a central bore 44 adjoining the threaded bore 43 and penetrating the output shaft 19.
  • the end of the adjusting screw 42 located in the bore 44 is designed as a valve seat 45 on which a valve ball 46 is applied under the force a compression spring 47.
  • the compression spring 47 also lies in the central bore 44 of the output shaft 19 and is supported on the end opposite the valve ball 46 on a shoulder 48 of the output shaft.
  • the adjusting screw 42 in the area between the valve seat 45 and the screw-in end is smaller in diameter than the bore 44 of the output shaft 19.
  • the bore 50 is located in the bottom of a depression 51 which receives a compression spring 27 for the lamella 26 in the part of the output shaft 19 located in the cylinder space 24.
  • the annular space 49 is sealed in both axial directions of the adjusting screw 42, so that it comes out of the cylinder space 24 in the hydraulic medium entering the annular space 49 cannot reach the outside or the screwdriver via the bore 44 of the output shaft 19.
  • the annular space 49 is connected via at least one, in the exemplary embodiment via two diametrically opposite bores 52 (FIG. 3) to a valve bore 53 which runs centrally in the adjusting screw 42 and which opens into the valve seat 45.
  • a trigger piston 54 adjoins the compression spring 47 for the valve ball 46 and is sealingly guided in the bore 44 of the output shaft 19.
  • the trigger piston 54 bears against a plunger 55 which is arranged in a bore 56 which penetrates the motor shaft 9 centrally.
  • the plunger 55 also abuts the locking piston 35, which is under the force of a compression spring 57 accommodated in the bore 56.
  • the output shaft 19 is rotated in a pulse-like manner when the screw or nut is seated on the parts to be screwed. As the angle of rotation increases, the torque to be applied also increases. That can now be done with the torque setting device 41 Limit torque can be set, when the screwdriver is automatically switched off.
  • valve bore 53 and the trigger piston 54 are selected such that the trigger piston 54 is displaced in the described manner in the bore 44 of the output shaft 19 as soon as the predetermined pressure of the hydraulic medium is reached.
  • the force of the compression spring 57 is set so that the trigger piston 54 over the Tappet 55 can move the locking piston 35 properly.
  • the output shaft 19 stops immediately, so that the screwing tool is actually stopped at the desired limit torque, so that the screw or nut to be tightened is not over-tightened.
  • the compression spring 11 pushes the shut-off valve 10 back into its release position, while the compression spring 57 pushes the locking piston 35 and, via the tappet 55, the release piston 54 back into the starting position shown in FIGS. 1 and 3.
  • the compression spring 47 finally pushes the valve ball 46 back into the valve seat 45. The screwdriver is thus ready for a next screwing operation.
  • the switch-off time and thus the limit torque can be set continuously with the adjusting screw 42.
  • the compression spring 47 is preloaded accordingly, so that the pressure of the hydraulic medium required for lifting the valve ball 46 can be set precisely depending on the desired limit torque and thus the switch-off time.
  • the annular space 49 is so long that there is still a line connection via the bore 50 to the cylinder space 24 in both directions even with the maximum adjustment path of the adjusting screw 42.
  • the air motor 3 is preferably a reversible motor, so that the motor shaft 9 and the output shaft 19 can also be driven in the opposite direction of rotation, so that screws and nuts can also be loosened.
  • the hydraulic pressure builds up in the other cylinder chamber 24 ′′ as soon as the screwdriver is switched on when the sealing position according to FIG. 4 is reached on.
  • the cylinder chamber 24 ′′ is connected via a bore 59 (FIGS. 4 and 5) to the bore 44 of the output shaft 19 in the area between the adjusting screw 42 and the trigger piston 54.
  • the hydraulic pressure acting in the cylinder chamber 24 '' during reverse running thus has an effect on the valve ball 46 via the bore 59 and presses it firmly into the valve seat 45, so that the screwdriver is reliably switched off during reverse running, ie when screws and nuts are removed is prevented.
  • the bore 59 in the output shaft 19 is dimensioned such that the amount of oil flowing through the bore 44 of the output shaft 19 is not sufficient to displace the trigger piston 54. Since the sealing strips 36, 37 are relatively narrow compared to the circumference of the inner wall 28 of the cylinder part 16, the pressure in the cylinder chamber 24 ′′ during backward rotation is only a very short time compared to the time required for the remaining rotation of the cylinder part 16 .
  • the screwdriver is switched off in reverse in a known manner in that the switch 5 is released, whereby the toggle valve 6 is closed and the compressed air supply is prevented.
  • compensating bores 60 and 61 In the housing part 16 there are two compensating bores 60 and 61 (FIG. 2) in a reinforced wall area, which are also filled with the hydraulic medium. Both compensation bores 60, 61 are connected to one another, while the compensating bore 60 is also connected to the cylinder space 24 via a bore 62.
  • the compensation bores 60, 61 can receive hydraulic medium from the cylinder space 24 if it expands as a result of an increase in temperature. In addition, losses in hydraulic medium can be compensated for by leaks via the compensating holes.
  • a piston 63 is screwed into the compensating bore 60 at one end (FIG. 1). In the compensating bore 61, a further piston (not shown) is provided at the opposite end, which closes this compensating bore at the free end.
  • One compensating bore 60 is completely filled with hydraulic medium, while the other compensating bore is only partially filled with the hydraulic medium.
  • the piston (not shown) of one compensating bore can move in accordance with the amount of hydraulic medium in this bore.
  • the impact frequency of the striking mechanism 4 can be kept at a favorable value with the screwdriver, at which a temperature increase of the hydraulic medium does not occur or only occurs very little.
  • the viscosity of the hydraulic medium remains almost constant during the working time of the screwdriver.
  • the hydraulic medium becomes thinner due to a temperature rise, then there is a risk that the required pressure to open the valve ball 46 in the cylinder chamber 24 'is not reached during the screwing process, so that the screwdriver is also not automatically switched off.
  • the screwdriver works with an optimal number of strokes in relation to the heating of the hydraulic medium, the viscosity of the hydraulic medium remains approximately constant, so that the screwdriver switches off at the specified torque with certainty.
  • the annular gap 30 is provided between the screw housing 1 and the holding part 20.
  • the compressed air motor 3 generates an air flow which can reach the annular gap 30 via the roller bearings 13, 32. Since it is very narrow, of the order of magnitude of only a few tenths of a millimeter, the air flows through this annular space 30 at a relatively high speed and thus intensively cools the holding part 20 and thus also the cylinder part 16. The air then flows forward over it Rolling bearing 31 and the passage point for the output shaft 19 from the screw housing 1. Of course, it is also possible to provide additional grooves in the holding part 20 for increasing the surface area for the cooling air.

Description

Die Erfindung betrifft einen Hydroimpulsschrauber nach dem Oberbegriff des Anspruchs 1, vgl. z.B. EP-A-0 070 325.The invention relates to a hydro impulse wrench according to the preamble of claim 1, cf. e.g. EP-A-0 070 325.

Aus der EP-A-70 325 ist ein Hydroimpulsschrauber bekannt, dessen Ventil zur Drehmomentbegrenzung im Zylinder selbst angeordnet ist, der die Abtriebswelle umgibt. Der vom Auslösekolben der Stellstange begrenzte zentrale Druckraum muß daher über eine Vielzahl von Bohrungen mit dem Druckentlastungsventil und der Zylinderkammer verbunden werden. Da die Zylinderwandung nicht sehr stark ist, ist die Anordnung der Bohrungen aufwendig und teuer.From EP-A-70 325 a hydro impulse wrench is known, the valve for torque limitation is arranged in the cylinder itself, which surrounds the output shaft. The central pressure chamber bounded by the actuating piston of the actuating rod must therefore be connected to the pressure relief valve and the cylinder chamber via a large number of bores. Since the cylinder wall is not very strong, the arrangement of the bores is complex and expensive.

Bei dem Hydroimpulsschrauber nach der US-A-3 334 487 ist der Auslösekolben in einer zentralen Bohrung der Antriebswelle gelagert. Die Bohrung ist als Sackloch ausgeführt.In the hydro impulse screwdriver according to US-A-3 334 487, the trigger piston is mounted in a central bore of the drive shaft. The hole is designed as a blind hole.

Zur Drehmomentbegrenzung ist die Stellstange von einer von außen einstellbaren Druckfeder beaufschlagt. Der auf die Stellstange wirkende hydraulische Druck muß die Federkraft überwinden um die Abschaltvorrichtung zu betätigen. Ein Druckentlastungsventil zwischen der Zylinderkammer und dem Druckraum ist nicht vorgesehen.To limit the torque, the actuating rod is acted upon by an externally adjustable compression spring. The hydraulic pressure acting on the control rod must overcome the spring force in order to actuate the switch-off device. A pressure relief valve between the cylinder chamber and the pressure chamber is not provided.

Der Erfindung liegt die Aufgabe zugrunde, einen gattungsgemäßen Hydroimpulsschrauber derart auszubilden, daß bei konstruktiv einfachem Aufbau des Druckentlastungsventils eine Einstellung des Drehmomentes schnell und einfach möglich ist.The invention has for its object to design a generic hydraulic impulse wrench in such a way that with a structurally simple structure of the pressure relief valve, an adjustment of the torque is possible quickly and easily.

Die Aufgabe wird erfindungsgemäß nach den kennzeichnenden Merkmalen des Anspruchs 1 gelöst. Aufgrund der konstruktiven Anordnung des Druckentlastungsventils in der zentralen durchgehenden Bohrung ist eine einfache und kostengünstige Herstellung gewährleistet. Die Einstellschraube ist in dem dem Schrauberkopf zugewandten Ende der Bohrung eingedreht und daher axial von der freien Stirnseite der Antriebswelle aus zugänglich. Die Einstellschraube kann also leicht erreicht werden, so daß eine rasche Einstellung des Abschalt-Drehmomentes möglich ist. Die konstruktive Ausbildung gewährleistet, daß der Druckluftmotor des Schraubers immer entsprechend dem eingestellten Drehmoment abgeschaltet wird, wobei ein vorzeitiger Abbruch des Schraubvorgangs sicher vermieden ist.The object is achieved according to the characterizing features of claim 1. Due to the structural arrangement of the pressure relief valve in the central through hole, simple and inexpensive manufacture is ensured. The adjusting screw is screwed into the end of the bore facing the screwdriver head and is therefore accessible axially from the free end face of the drive shaft. The adjusting screw can therefore be easily reached, so that the shutdown torque can be set quickly. The constructive design ensures that the compressed air motor of the screwdriver is always switched off according to the set torque, with premature termination of the screwing process being reliably avoided.

Weitere Merkmale der Erfindung ergeben sich aus den weiteren Ansprüchen, der Beschreibung und den Zeichnungen, in der ein nachfolgend im einzelnen beschriebenes Ausführungsbeispiel der Erfindung dargestellt ist.
Es zeigen:

Fig. 1
einen Schnitt durch einen erfindungsgemäßen Hydroimpulsschrauber,
Fig. 2
einen Schnitt durch ein Schlagwerk des Hydroimpulsschraubers, das eine Lage einnimmt, in der auf die Abtriebswelle kein Schlag ausgeübt wird,
Fig. 3
in vergrößerter Darstellung und im Schnitt die Lage einer Drehmomenteinstelleinrichtung bei der in Fig. 2 dargestellten Lage des Schlagwerkes,
Fig. 4 und 5
in Darstellungen entsprechend den Fig. 2 und 3 das Schlagwerk und die Drehmomenteinstelleinrichtung in einer Lage, in der auf die Abtriebswelle ein Schlag ausgeübt wird.
Further features of the invention result from the further claims, the description and the drawings, in which an embodiment of the invention described in detail below is shown.
Show it:
Fig. 1
4 shows a section through a hydro impulse screwdriver according to the invention,
Fig. 2
a section through a striking mechanism of the hydraulic impulse wrench, which assumes a position in which no impact is exerted on the output shaft,
Fig. 3
in an enlarged representation and in section, the position of a torque setting device in the position of the striking mechanism shown in FIG. 2,
4 and 5
in representations corresponding to FIGS. 2 and 3, the striking mechanism and the torque setting device in a position in which a shock is exerted on the output shaft.

Der Hydro-Impulsschrauber hat ein Gehäuse 1 mit einem Griff 2. Im Gehäuse 1 sind ein Druckluftmotor 3 und ein Schlagwerk 4 untergebracht. Im Griff 2 ist ein Schalter 5 gelagert, mit dem ein Kippventil 6 betätigt werden kann. Es liegt in einer Druckluftzuführung 7 im Griff 2. Er weist in bekannter Weise einen (nicht dargestellten) Druckluftanschluß auf. Die Druckluftzuführung 7 mündet in eine Druckluftkammer 8 im Gehäuse 1, die durch ein auf einer Motorwelle 9 axial verschiebbares Absperrventil 10 gegen den Druckluftmotor 3 geschlossen werden kann. Das Absperrventil 10 ist gegen die Kraft einer die Motorwelle 9 umgebenden Druckfeder 11 in seine Schließstellung verschiebbar. Die Motorwelle 9 ist über zwei Wälzlager 12 und 13 im Gehäuse 1 drehbar gelagert. Auf dem vom Absperrventil 10 abgewandten Ende sitzt auf der Motorwelle 9 drehfest ein hülsenförmiger Endteil 15 eines Schlagwerkdeckels 14 des Schlagwerkes 4. Der Schlagwerkdeckel 14 liegt senkrecht zur Achse der Motorwelle 9 und ist am radial äußeren Ende durch einen Zylinderteil 16 mit einem gegenüberliegenden Schlagwerkdeckel 17 drehfest verbunden. Er ist mit einem hülsenförmigen Endteil 18 auf einer Abtriebswelle 19 gelagert, auf der auch der Endteil 15 des Schlagwerkdeckels 14 gelagert ist. Die Abtriebswelle 19 endet mit geringem Abstand von der Motorwelle 9. Die beiden Schlagwerkdeckel 14, 17 und der Zylinderteil 16 werden von einem zylindrischen Halteteil 20 umgeben, der den Schlagwerkdeckel 17 am radial äußeren Rand mit einem radial nach innen gerichteten Bund 21 übergreift und am gegenüberliegenden Ende eine Vertiefung 22 aufweist, in die ein Spannring 23 geschraubt ist, mit dem die Schlagwerkdeckel 14, 17 und der Zylinderteil 16 gegen den Bund 21 und gegeneinander verspannt werden.The hydraulic impulse wrench has a housing 1 with a handle 2. A compressed air motor 3 and a striking mechanism 4 are accommodated in the housing 1. A switch 5 is mounted in the handle 2, with which a toggle valve 6 can be actuated. It lies in a compressed air supply 7 in the handle 2. It has a compressed air connection (not shown) in a known manner. The compressed air supply 7 opens into a compressed air chamber 8 in the housing 1, which can be closed against the compressed air motor 3 by a shut-off valve 10 which is axially displaceable on a motor shaft 9. The shut-off valve 10 can be displaced into its closed position against the force of a compression spring 11 surrounding the motor shaft 9. The motor shaft 9 is rotatably mounted in the housing 1 via two roller bearings 12 and 13. On the end facing away from the shut-off valve 10, a sleeve-shaped end part 15 of a striking mechanism cover 14 of the striking mechanism 4 is seated on the motor shaft 9 in a rotationally fixed manner connected. It is mounted with a sleeve-shaped end part 18 on an output shaft 19, on which the end part 15 of the striking mechanism cover 14 is also mounted. The output shaft 19 ends at a short distance from the motor shaft 9. The two striking mechanism covers 14, 17 and the cylinder part 16 are surrounded by a cylindrical holding part 20 which overlaps the striking mechanism cover 17 at the radially outer edge with a radially inwardly directed collar 21 and has a recess 22 at the opposite end, into which a clamping ring 23 is screwed which the striking mechanism cover 14, 17 and the cylinder part 16 are braced against the collar 21 and against each other.

Die Schlagwerkdeckel 14 und 17 sowie der Zylinderteil 16 begrenzen einen Zylinderraum 24 (Fig. 2), der exzentrisch in dem von den Schlagwerkdeckeln 14, 17 und dem Zylinderteil 16 gebildeten Zylinder des Schlagwerkes 4 vorgesehen ist. Die Abtriebswelle 19 durchsetzt diesen Zylinderraum 24 und ist exzentrisch in bezug auf die Achse dieses Zylinderraumes 24 angeordnet. Die Abtriebswelle 19 ist im Bereich innerhalb des Zylinderraumes 24 als Schlagamboß ausgebildet, der die in den Fig. 2 und 4 dargestellte Form hat. Im Bereich außerhalb des Zylinderraumes 24 ist die Abtriebswelle zylindrisch ausgebildet. Die Abtriebswelle 19 weist innerhalb des Zylinderrraumes 24 eine Vertiefung 25 auf (Fig. 2), die sich über die Länge des Zylinderraumes 24 erstreckt und in der eine Lamelle 26 radial verschiebbar untergebracht ist. Sie steht unter der Kraft von zwei Druckfedern 27 (Fig. 1), welche die Lamelle 26 radial nach außen gegen die Innenwandung 28 (Fig. 2) des Zylinderteiles 16 drücken. Die Druckfedern 27 liegen mit einem Ende in Vertiefungen 29 in der Lamelle 26.The striking mechanism covers 14 and 17 and the cylinder part 16 delimit a cylinder space 24 (FIG. 2) which is provided eccentrically in the cylinder of the striking mechanism 4 formed by the striking mechanism covers 14, 17 and the cylinder part 16. The output shaft 19 passes through this cylinder space 24 and is arranged eccentrically with respect to the axis of this cylinder space 24. The output shaft 19 is formed in the area within the cylinder space 24 as a striking anvil, which has the shape shown in FIGS. 2 and 4. In the area outside the cylinder space 24, the output shaft is cylindrical. The output shaft 19 has a recess 25 within the cylinder space 24 (FIG. 2), which extends over the length of the cylinder space 24 and in which a lamella 26 is accommodated in a radially displaceable manner. It is under the force of two compression springs 27 (FIG. 1) which press the lamella 26 radially outward against the inner wall 28 (FIG. 2) of the cylinder part 16. The compression springs 27 have one end in recesses 29 in the lamella 26.

Der Zylinderteil 16 wird unter Bildung eines Ringspaltes 30 vom Gehäuse 1 umgeben. Die Abtriebswelle 19 ist im Gehäuse 1 mit Wälzlagern 31, 32 drehbar gelagert. Auf dem aus dem Gehäuse 1 ragenden Ende der Abtriebswelle 19 sitzt drehfest eine Aufnahme 33, beispielsweise ein Spannfutter, für Schraubwerkzeuge.The cylinder part 16 is surrounded by the housing 1 to form an annular gap 30. The output shaft 19 is rotatably mounted in the housing 1 with roller bearings 31, 32. A receptacle 33, for example a chuck, for screwing tools sits on the end of the output shaft 19 protruding from the housing 1.

Die Abtriebswelle 19 ist relativ zu den Schlagwerkdeckeln 14, 17 und zum Zylinderteil 16 drehbar. Der Zylinderraum 24 ist vollständig mit Druckmedium, vorzugsweise mit Drucköl, gefüllt.The output shaft 19 is rotatable relative to the striking mechanism covers 14, 17 and the cylinder part 16. The cylinder space 24 is completely filled with pressure medium, preferably with pressure oil.

Zum Starten des Hydro-Impulsschraubers wird der Schalter 5 gedrückt, so daß das Kippventil 6 in seine Offenstellung gelangt und Druckluft über die Druckluftzuführung 7 in die Druckluftkammer 8 gelangen kann. Das Absperrventil 10 wird durch eine Sperrkugel 34, die radial verschieblich in der Motorwelle 9 gelagert und durch einen Sperrkolben 35 in der Sperrstellung gehalten ist, in seiner Offenstellung gehalten. Die Druckluft kann somit durch das geöffnete Absperrventil 10 zum Drucklufmotor 3 gelangen und ihn in bekannter Weise antreiben. Die Motorwelle 9 des Druckluftmotors 3 treibt die Schlagwerkdeckel 14 und 17 und den Zylinderteil 16 unmittelbar an. Über das im Zylinderraum 24 befindliche Druckmedium wird hierbei auch die Abtriebswelle 19 rotierend mitgenommen. Somit wird das in die Aufnahme 33 eingesetzte Schraubwerkzeug gedreht und eine Schraube oder Mutter in den jeweiligen Bauteil geschraubt. Solange der Schraubenkopf oder die Mutter noch nicht aufliegt, drehen die Motorwelle 9 und die Abtriebswelle 19 gemeinsam. Sobald jedoch der Schraubenkopf bzw. die Mutter aufsitzt, erfährt die Abtriebswelle 19 eine Gegenkraft. Zum Anziehen der Schraube oder der Mutter ist es nunmehr notwendig, daß mit der Abtriebswelle 19 ein Drehmoment auf die Schraube oder die Mutter aufgebracht wird. Da die Motorwelle 9 mit den Schlagwerkdeckeln 14, 17 und dem Zylinderteil 16 gegenüber der Abtriebswelle 19 drehbar ist, wird die Motorwelle weiterhin drehbar angetrieben, so daß sich der Zylinder 14, 16, 17 relativ zur Abtriebswelle 19 dreht.To start the hydraulic pulse screwdriver, the switch 5 is pressed so that the toggle valve 6 reaches its open position and compressed air can reach the compressed air chamber 8 via the compressed air supply 7. The shut-off valve 10 is held in its open position by a locking ball 34, which is mounted in the motor shaft 9 in a radially displaceable manner and is held in the locking position by a locking piston 35. The compressed air can thus reach the compressed air motor 3 through the opened shut-off valve 10 and drive it in a known manner. The motor shaft 9 of the compressed air motor 3 drives the striking mechanism covers 14 and 17 and the cylinder part 16 directly. The output shaft 19 is also rotatably carried along by the pressure medium in the cylinder space 24. The screwing tool inserted into the receptacle 33 is thus rotated and a screw or nut is screwed into the respective component. As long as the screw head or the nut is not yet in contact, the motor shaft 9 and the output shaft 19 rotate together. However, as soon as the screw head or nut is seated, the output shaft 19 experiences a counterforce. To tighten the screw or the nut, it is now necessary that a torque is applied to the screw or the nut with the output shaft 19. Since the motor shaft 9 with the striking mechanism covers 14, 17 and the cylinder part 16 can be rotated with respect to the output shaft 19, the motor shaft is still rotatably driven, so that the cylinder 14, 16, 17 rotates relative to the output shaft 19.

Wie Fig. 2 zeigt, sind an der Innenwandung 28 des Zylinderteiles 16 zwei radial nach innen ragende und diametral einander gegenüberliegende Dichtleisten 36 und 37 vorgesehen, die einstückig mit dem Zylinderteil 16 ausgebildet sind und eine koaxial zur zylindrischen Innenwandung 28 verlaufende, als Dichtfläche wirkende Stirnseite 38 und 39 haben.As shown in FIG. 2, two radially inwardly projecting and diametrically opposed sealing strips 36 and 37 are provided on the inner wall 28 of the cylinder part 16, which are formed in one piece with the cylinder part 16 and have an end face which acts coaxially with the cylindrical inner wall 28 and acts as a sealing surface Have 38 and 39.

Infolge der exzentrischen Anordnung der Abtriebswelle 19 im Zylinderraum 24 ist während des größten Teils der Rotation des Zylinderteiles 16 nur die Lamelle 26 der Abtriebswelle 19 mit der Innenwandung 28 des Zylinderteiles 16 in Berührung. Durch die Druckfedern 27 wird die Lamelle 26 federnd gegen die Innenwand 28 gedrückt, an der sie während der Rotation des Zylinderteiles 26 stets anliegt. Sobald der Zylinderteil 16 in die in Fig. 4 dargestellte Lage relativ zur Abtriebswelle 19 gelangt, sind gleichzeitig die Lamelle 26 und die gegenüberliegende Außenseite 40 der Abtriebswelle 19 in Berührung mit den Dichtleisten 36 und 37. Der Zylinderraum 24 ist dadurch in zwei Zylinderräume 24′, 24'' aufgeteilt, die durch die Lamelle 26 und die Abtriebswelle 19 gegeneinander abgedichtet sind. Das Hydraulikmedium in der Zylinderkammer 24′ wird unter Druck gesetzt, weil das Medium nicht mehr in die Zylinderkammer 24'' ausweichen kann. Der hierbei sich aufbauende Druck wird auf den im Zylinderraum befindlichen Teil der Abtriebswelle 19 übertragen, die dadurch ruckartig in Drehrichtung des Zylinderteiles 16 gedreht wird. Sobald die in Fig. 4 dargestellte Dichtstellung überfahren wird, kommt der Rand 40 der Abtriebswelle 19 von der Dichtleiste 36 frei, so daß das Hydraulikmedium aus der Zylinderkammer 24′ wieder in die Zylinderkammer 24'' gelangen kann. Da während der Dichtstellung (Fig. 4) das Hydraulikmedium nicht bzw. nur sehr langsam aus der Zylinderkammer 24′ verdrängt werden kann, wird der Zylinderteil 16 und damit der Druckluftmotor 3 abgebremst. Sobald die Dichtstellung jedoch überfahren wird und der Druck abgebaut werden kann, beschleunigt der Druckluftmotor 3 wieder, bis nach einer Umdrehung wiederum die in Fig. 4 dargestellte Dichtstellung erreicht ist. Auf diese Weise wird die Abtriebswelle 19 und damit das jeweilige Schraubewerkzeug impulsartig gedreht.As a result of the eccentric arrangement of the output shaft 19 in the cylinder chamber 24, only the lamella 26 of the output shaft 19 is in contact with the inner wall 28 of the cylinder part 16 during most of the rotation of the cylinder part 16. By means of the compression springs 27, the lamella 26 is pressed resiliently against the inner wall 28, against which it always bears during the rotation of the cylinder part 26. As soon as the cylinder part 16 reaches the position shown in FIG. 4 relative to the output shaft 19, the lamella 26 and the opposite outer side 40 of the output shaft 19 are in contact with the sealing strips 36 and 37 at the same time. The cylinder space 24 is thereby in two cylinder spaces 24 ' , 24 '', which are sealed against each other by the lamella 26 and the output shaft 19. The hydraulic medium in the cylinder chamber 24 'is pressurized because the medium can no longer escape into the cylinder chamber 24''. The pressure that builds up here is transmitted to the part of the output shaft 19 located in the cylinder space, which is then jerkily rotated in the direction of rotation of the cylinder part 16. As soon as the sealing position shown in Fig. 4 is passed, the edge 40 of the output shaft 19 is free from the sealing strip 36, so that the hydraulic medium from the cylinder chamber 24 'can get back into the cylinder chamber 24''. Since during the sealing position (Fig. 4) the hydraulic medium can not or only very slowly be displaced from the cylinder chamber 24 ', the cylinder part 16 and thus the compressed air motor 3 is braked. Once the sealing position However, if the vehicle is run over and the pressure can be reduced, the compressed air motor 3 accelerates again until after one revolution the sealing position shown in FIG. 4 is reached again. In this way, the output shaft 19 and thus the respective screwing tool is rotated in pulses.

Da Schrauben oder Muttern bis zu einem vorgegebenen Drehmoment angezogen werden müssen, ist es notwendig, daß der Schraubvorgang exakt bei diesem vorgegebenen Grenzdrehmoment abgebrochen wird. Beim Hydro-Impulsschrauber wird der im Zylinderraum 24 in der Dichtstellung der Abtriebswelle 19 sich aufbauende Druck zur Bestimmung des Abschaltzeitpunktes bei dem vorgegebenen Grenzdrehmoment herangezogen. Der Schrauber ist zu diesem Zweck mit einer Drehmomenteinstelleinrichtung 41 versehen (Fig. 1), mit der in Abhängigkeit vom Hydraulikdruck im Zylinderraum 24 der Schrauber bei Erreichen des vorgegebenen Grenzdrehmomentes einwandfrei automatisch abgeschaltet wird. Die Drehmomenteinstelleinrichtung 41 hat eine Einstellschraube 42, die in eine koaxiale Gewindebohrung 43 in der Abtriebswelle 19 geschraubt ist. Infolge dieser Anordnung ist die Einstellschraube 42 bequem zur Einstellung des Abschaltzeitpunktes des Schraubers zugänglich. Die Einstellschraube 42 erstreckt sich mit einem gewindefreien Abschnitt in eine zentrische, an die Gewindebohrung 43 anschließende und die Abtriebswelle 19 durchsetzende Bohrung 44. Das in der Bohrung 44 befindliche Ende der Einstellschraube 42 ist als Ventilsitz 45 ausgebildet, auf dem eine Ventilkugel 46 unter der Kraft einer Druckfeder 47 liegt. Die Druckfeder 47 liegt ebenfalls in der zentrischen Bohrung 44 der Abtriebswelle 19 und stützt sich an dem der Ventilkugel 46 gegenüberliegenden Ende an einem Absatz 48 der Abtriebswelle ab.Since screws or nuts have to be tightened to a predetermined torque, it is necessary that the screwing process is stopped exactly at this predetermined limit torque. In the hydraulic impulse wrench, the pressure building up in the cylinder chamber 24 in the sealing position of the output shaft 19 is used to determine the switch-off time at the predetermined limit torque. For this purpose, the screwdriver is provided with a torque setting device 41 (FIG. 1) with which, depending on the hydraulic pressure in the cylinder space 24, the screwdriver is automatically switched off correctly when the predetermined limit torque is reached. The torque setting device 41 has an adjusting screw 42 which is screwed into a coaxial threaded bore 43 in the output shaft 19. As a result of this arrangement, the adjusting screw 42 is easily accessible for setting the switch-off time of the screwdriver. The adjusting screw 42 extends with a thread-free section into a central bore 44 adjoining the threaded bore 43 and penetrating the output shaft 19. The end of the adjusting screw 42 located in the bore 44 is designed as a valve seat 45 on which a valve ball 46 is applied under the force a compression spring 47. The compression spring 47 also lies in the central bore 44 of the output shaft 19 and is supported on the end opposite the valve ball 46 on a shoulder 48 of the output shaft.

Wie Fig. 3 deutlich zeigt, ist die Einstellschraube 42 im Bereich zwischen dem Ventilsitz 45 und dem einschraubseitigen Ende (Fig. 1) im Durchmesser kleiner als die Bohrung 44 der Abtriebswelle 19. Dadurch wird ein die Einstellschraube 42 umgebender Ringraum 49 gebildet, der über eine Bohrung 50 in der Abtriebswelle 19 mit dem Zylinderraum 24 verbunden ist. Die Bohrung 50 befindet sich im Boden einer die eine Druckfeder 27 für die Lamelle 26 aufnehmenden Vertiefung 51 in dem im Zylinderraum 24 befindlichen Teil der Abtriebswelle 19. Der Ringraum 49 ist in beiden Axialrichtungen der Einstellschraube 42 abgedichtet, so daß das aus dem Zylinderraum 24 in den Ringraum 49 gelangende Hydraulikmedium nicht über die Bohrung 44 der Abtriebswelle 19 nach außen bzw. in den Schrauber gelangen kann.As clearly shown in FIG. 3, the adjusting screw 42 in the area between the valve seat 45 and the screw-in end (FIG. 1) is smaller in diameter than the bore 44 of the output shaft 19. This forms an annular space 49 surrounding the adjusting screw 42, which over a bore 50 in the output shaft 19 is connected to the cylinder space 24. The bore 50 is located in the bottom of a depression 51 which receives a compression spring 27 for the lamella 26 in the part of the output shaft 19 located in the cylinder space 24. The annular space 49 is sealed in both axial directions of the adjusting screw 42, so that it comes out of the cylinder space 24 in the hydraulic medium entering the annular space 49 cannot reach the outside or the screwdriver via the bore 44 of the output shaft 19.

Der Ringraum 49 ist über wenigstens eine, im Ausführungsbeispiel über zwei diametral einander gegenüberliegende Bohrungen 52 (Fig. 3) mit einer zentrisch in der Einstellschraube 42 verlaufenden Ventilbohrung 53 verbunden, die in den Ventilsitz 45 mündet. An die Druckfeder 47 für die Ventilkugel 46 schließt ein Auslösekolben 54 an, der dichtend in der Bohrung 44 der Abtriebswelle 19 geführt ist. Der Auslösekolben 54 liegt an einem Stößel 55 an, der in einer die Motorwelle 9 zentrisch durchsetzenden Bohrung 56 angeordnet ist. Der Stößel 55 liegt außerdem am Sperrkolben 35 an, der unter der Kraft einer in der Bohrung 56 untergebrachten Druckfeder 57 steht. Wenn der Hydro-Impulsschrauber läuft, nehmen der Auslösekolben 54 und der Sperrkolben 35 die in Fig. 1 dargestellte Lage ein. Beim Schraubvorgang wird in der beschriebenen Weise die Abtriebswelle 19 impulsartig gedreht, wenn die Schraube oder die Mutter auf den zu verschraubenden Teilen aufsitzt. Mit zunehmendem Verdrehwinkel nimmt auch das aufzubringende Drehmoment zu. Mit der Drehmomenteinstelleinrichtung 41 kann nun dasjenige Grenzdrehmoment eingestellt werden, bei dessen Erreichen der Schrauber automatisch abgeschaltet wird. Bei jeder Umdrehung des Zylinderteiles 16 nimmt der Druck in der Zylinderkammer 24′ in der Dichtstellung der Abtriebswelle 19 zu. Da die Zylinderkammer 24′ über die Bohrung 50 mit dem Ringraum 49 und über die Bohrungen 52 mit der Ventilbohrung 53 in Leitungsverbindung ist, wirkt sich der in der Zylinderkammer 24′ herrschende Druck auch auf die Ventilkugel 46 auf. Sie wird durch die Druckfeder 47 mit einer vorgegebenen Kraft in den Ventilsitz 45 gedrückt. Mit zunehmender Zahl von Schlägen über die Abtriebswelle 16 steigt der Druck des Hydraulikmediums in der Zylinderkammer 24′ und damit auch in der Ventilbohrung 53. Sobald dieser Druck die auf die Ventilkugel 46 wirkende Federkraft überschreitet, wird die Ventilkugel vom Ventilsitz 45 abgehoben, so daß ein kleiner Teil des Hydraulikmediums aus der Ventilbohrung 53 in die Bohrung 44 der Abtriebswelle 19 im Bereich zwischen der Einstellschraube 42 und dem Auslösekolben 54 gelangt. Er wird durch das Hydraulikmedium in Fig. 1 nach rechts verschoben, wodurch über den Stößel 55 der Sperrkolben 35 gegen die Kraft der Druckfeder 57 verschoben wird. Der Sperrkolben 35 hat eine Ringnut 58, die hierbei in den Bereich der Sperrkugel 34 gelangt, die dadurch radial nach innen ausweichen kann und das Absperrventil 10 freigibt. Infolge des in der Druckluftkammer 8 herrschenden Druckes wird das Absperrventil 10 gegen die Kraft der Druckfeder 11 in seine Schließstellung gedrückt. Dadurch wird die Druckluftzufuhr zum Motor 3 unterbrochen und der Schrauber augenblicklich abgeschaltet.The annular space 49 is connected via at least one, in the exemplary embodiment via two diametrically opposite bores 52 (FIG. 3) to a valve bore 53 which runs centrally in the adjusting screw 42 and which opens into the valve seat 45. A trigger piston 54 adjoins the compression spring 47 for the valve ball 46 and is sealingly guided in the bore 44 of the output shaft 19. The trigger piston 54 bears against a plunger 55 which is arranged in a bore 56 which penetrates the motor shaft 9 centrally. The plunger 55 also abuts the locking piston 35, which is under the force of a compression spring 57 accommodated in the bore 56. When the hydraulic pulse screwdriver is running, the trigger piston 54 and the locking piston 35 assume the position shown in FIG. 1. During the screwing process, the output shaft 19 is rotated in a pulse-like manner when the screw or nut is seated on the parts to be screwed. As the angle of rotation increases, the torque to be applied also increases. That can now be done with the torque setting device 41 Limit torque can be set, when the screwdriver is automatically switched off. With each revolution of the cylinder part 16, the pressure in the cylinder chamber 24 'increases in the sealing position of the output shaft 19. Since the cylinder chamber 24 'is in line connection via the bore 50 with the annular space 49 and via the bores 52 with the valve bore 53, the pressure prevailing in the cylinder chamber 24' also acts on the valve ball 46. It is pressed into the valve seat 45 by the compression spring 47 with a predetermined force. With increasing number of blows on the output shaft 16, the pressure of the hydraulic medium in the cylinder chamber 24 'and thus also in the valve bore 53. As soon as this pressure exceeds the spring force acting on the valve ball 46, the valve ball is lifted off the valve seat 45, so that a Small part of the hydraulic medium from the valve bore 53 enters the bore 44 of the output shaft 19 in the area between the adjusting screw 42 and the trigger piston 54. It is shifted to the right by the hydraulic medium in FIG. 1, whereby the locking piston 35 is displaced against the force of the compression spring 57 via the tappet 55. The locking piston 35 has an annular groove 58, which in this case reaches the area of the locking ball 34, which can thereby move radially inwards and releases the shut-off valve 10. As a result of the pressure prevailing in the compressed air chamber 8, the shut-off valve 10 is pressed into its closed position against the force of the compression spring 11. As a result, the compressed air supply to motor 3 is interrupted and the screwdriver is switched off immediately.

Die Abmessungen der Ventilbohrung 53 und des Auslösekolbens 54 sind so gewählt, daß unmittelbar bei Erreichen des vorgegebenen Druckes des Hydraulikmediums der Auslösekolben 54 in der beschriebenen Weise in der Bohrung 44 der Abtriebswelle 19 verschoben wird. Die Kraft der Druckfeder 57 ist so eingestellt, daß der Auslösekolben 54 über den Stößel 55 den Sperrkolben 35 einwandfrei verschieben kann. Nach dem Abschalten des Druckluftmotors 3 steht die Abtriebswelle 19 augenblicklich still, so daß auch tatsächlich bei dem gewünschten Grenzdrehmoment das Schraubwerkzeug stillgesetzt wird, so daß die anzuziehende Schraube oder Mutter nicht überdreht wird. Nach dem Abschalten erfolgt ein Druckabbau im Zylinderraum 24 sowie in der Druckluftkammer 8, so daß die die Abschaltung des Schraubers bewirkenden Teile wieder in ihre in Fig. 1 dargestellte Ausgangslage zurückgeschoben werden. Die Druckfeder 11 schiebt das Absperrventil 10 in seine Freigabestellung zurück, während die Druckfeder 57 den Sperrkolben 35 und über den Stößel 55 den Auslösekolben 54 in die in den Fig. 1 und 3 dargestellte Ausgangslage zurückschieben. Die Druckfeder 47 schließlich drückt die Ventilkugel 46 wieder in den Ventilsitz 45. Der Schrauber ist damit bereit für einen nächsten Schraubgang.The dimensions of the valve bore 53 and the trigger piston 54 are selected such that the trigger piston 54 is displaced in the described manner in the bore 44 of the output shaft 19 as soon as the predetermined pressure of the hydraulic medium is reached. The force of the compression spring 57 is set so that the trigger piston 54 over the Tappet 55 can move the locking piston 35 properly. After switching off the compressed air motor 3, the output shaft 19 stops immediately, so that the screwing tool is actually stopped at the desired limit torque, so that the screw or nut to be tightened is not over-tightened. After switching off, there is a reduction in pressure in the cylinder chamber 24 and in the compressed air chamber 8, so that the parts causing the screwdriver to be switched off are pushed back into their starting position shown in FIG. 1. The compression spring 11 pushes the shut-off valve 10 back into its release position, while the compression spring 57 pushes the locking piston 35 and, via the tappet 55, the release piston 54 back into the starting position shown in FIGS. 1 and 3. The compression spring 47 finally pushes the valve ball 46 back into the valve seat 45. The screwdriver is thus ready for a next screwing operation.

Der Abschaltzeitpunkt und damit das Grenzdrehmoment kann mit der Einstellschraube 42 stufenlos eingestellt werden. Durch Verdrehen der Einstellschraube 42 wird die Druckfeder 47 entsprechend vorgespannt, so daß je nach gewünschtem Grenzdrehmoment und damit Abschaltzeitpunkt der zum Abheben der Ventilkugel 46 notwendige Druck des Hydraulikmediums genau eingestellt werden kann. Der Ringraum 49 ist so lang, daß auch bei maximalem Verstellweg der Einstellschraube 42 in beiden Richtungen noch eine Leitungsverbindung über die Bohrung 50 zum Zylinderraum 24 gegeben ist.The switch-off time and thus the limit torque can be set continuously with the adjusting screw 42. By turning the adjusting screw 42, the compression spring 47 is preloaded accordingly, so that the pressure of the hydraulic medium required for lifting the valve ball 46 can be set precisely depending on the desired limit torque and thus the switch-off time. The annular space 49 is so long that there is still a line connection via the bore 50 to the cylinder space 24 in both directions even with the maximum adjustment path of the adjusting screw 42.

Der Druckluftmotor 3 ist vorzugsweise ein reversibler Motor, so daß die Motorwelle 9 und die Abtriebswelle 19 auch in entgegengesetzter Drehrichtung angetrieben werden können, so daß sich Schrauben und Muttern auch lösen lassen können. In diesem Falle baut sich sofort nach Einschalten des Schraubers in der anderen Zylinderkammer 24'' bei Erreichen der Dichtstellung gemäß Fig. 4 der Hydraulikdruck auf. Die Zylinderkammer 24'' ist über eine Bohrung 59 (Fig. 4 und 5) mit der Bohrung 44 der Abtriebswelle 19 im Bereich zwischen der Einstellschraube 42 und dem Auslösekolben 54 verbunden. Der in der Zylinderkammer 24'' beim Rückwärtslauf wirkende Hydraulikdruck wirkt sich somit über die Bohrung 59 auf die Ventilkugel 46 aus und drückt sie fest in den Ventilsitz 45, so daß eine Abschaltung des Schraubers beim Rückwärtslauf, d.h. beim Herausdrehen von Schrauben und Muttern, zuverlässig unterbunden wird. Die Bohrung 59 in der Abtriebswelle 19 ist so dimensioniert, daß die Ölmenge, die durch die Bohrung 44 der Abtriebswelle 19 strömt, nicht ausreicht, den Auslösekolben 54 zu verschieben. Da die Dichtleisten 36, 37 verhältnismäßig schmal sind im Vergleich zum Umfang der Innenwandung 28 des Zylinderteiles 16, steht der Druck in der Zylinderkammer 24'' beim Rückwärtslauf nur eine sehr geringe Zeit an, verglichen mit der für die übrige Drehung des Zylinderteiles 16 notwendigen Zeit. Während dieser verhältnismäßig langen Zeit kann die Ölmenge in der Bohrung 44 wieder in die Zylinderkammer 24 zurückströmen, so daß sich bei der nächsten Impulsbeaufschlagung der Abtriebswelle 19 keine Summierung der gleichen Ölmenge ergibt. Dadurch wird zuverlässig verhindert, daß sich beim Rückwärtslauf in der Zylinderkammer 24'' ein stetig sich vergrößerndes Volumen aufbaut, das den Auslösekolben 54 verschieben und damit einen Abschaltvorgang auslösen würde.The air motor 3 is preferably a reversible motor, so that the motor shaft 9 and the output shaft 19 can also be driven in the opposite direction of rotation, so that screws and nuts can also be loosened. In this case, the hydraulic pressure builds up in the other cylinder chamber 24 ″ as soon as the screwdriver is switched on when the sealing position according to FIG. 4 is reached on. The cylinder chamber 24 ″ is connected via a bore 59 (FIGS. 4 and 5) to the bore 44 of the output shaft 19 in the area between the adjusting screw 42 and the trigger piston 54. The hydraulic pressure acting in the cylinder chamber 24 '' during reverse running thus has an effect on the valve ball 46 via the bore 59 and presses it firmly into the valve seat 45, so that the screwdriver is reliably switched off during reverse running, ie when screws and nuts are removed is prevented. The bore 59 in the output shaft 19 is dimensioned such that the amount of oil flowing through the bore 44 of the output shaft 19 is not sufficient to displace the trigger piston 54. Since the sealing strips 36, 37 are relatively narrow compared to the circumference of the inner wall 28 of the cylinder part 16, the pressure in the cylinder chamber 24 ″ during backward rotation is only a very short time compared to the time required for the remaining rotation of the cylinder part 16 . During this relatively long time, the amount of oil in the bore 44 can flow back into the cylinder chamber 24, so that the next time the output shaft 19 receives impulses, there is no summation of the same amount of oil. This reliably prevents a steadily increasing volume from building up in the cylinder chamber 24 ″ during reverse travel, which would displace the trigger piston 54 and thus trigger a shutdown process.

Der Schrauber wird beim Rückwärtslauf in bekannter Weise dadurch abgeschaltet, daß der Schalter 5 freigegeben wird, wodurch das Kippventil 6 geschlossen wird und die Druckluftzufuhr unterbindet.The screwdriver is switched off in reverse in a known manner in that the switch 5 is released, whereby the toggle valve 6 is closed and the compressed air supply is prevented.

Im Gehäuseteil 16 befinden sich in einem verstärkten Wandbereich zwei Ausgleichsbohrungen 60 und 61 (Fig. 2), die ebenfalls mit dem Hydraulikmedium gefüllt sind. Beide Ausgleichsbohrungen 60, 61 sind miteinander verbunden, während die Ausgleichsbohrung 60 außerdem über eine Bohrung 62 mit dem Zylinderraum 24 verbunden ist. Die Ausgleichsbohrungen 60, 61 können Hydraulikmedium aus dem Zylinderraum 24 aufnehmen, wenn es sich infolge einer Temperaturerhöhung ausdehnt. Außerdem können über die Ausgleichsbohrungen Verluste an Hydraulikmedium durch Leckagen ausgeglichen werden. In die Ausgleichsbohrung 60 ist an einem Ende ein Kolben 63 geschraubt (Fig. 1). In der Ausgleichsbohrung 61 ist am gegenüberliegenden Ende ein (nicht dargestellter) weiterer Kolben vorgesehen, der diese Ausgleichsbohrung am freien Ende abschließt. Die eine Ausgleichsbohrung 60 ist vollständig mit Hydraulikmedium gefüllt, während die andere Ausgleichsbohrung nur teilweise mit dem Hydraulikmedium gefüllt ist. Je nach der Menge des Hydraulikmediums in den beiden Ausgleichsbohrungen kann sich der (nicht dargestellte) Kolben der einen Ausgleichsbohrung entsprechend der Menge des Hydraulikmediums in dieser Bohrung verschieben. Bei dem beschriebenen Hydro-Impulsschrauber ändern sich die Dichtverhältnisse zwischen Abtriebswelle 19 und Gehäuseteil 16 beim Arbeiten mit dem Schrauber nicht, weil die automatische Abschaltung des Schraubers über die in der Abtriebswelle untergebrachte Drehmomenteinstelleinrichtung 41 erreicht wird. Dadurch arbeitet dieser Schrauber unabhängig davon, ob weiche oder harte Teile miteinander verschraubt werden sollen, mit der gleichen Schlagfrequenz. Dadurch kann mit dem Schrauber die Schlagfrequenz des Schlagwerkes 4 auf einem günstigen Wert gehalten werden, bei der eine Temperaturzunahme des Hydraulikmediums nicht oder nur sehr wenig auftritt. Dadurch bleibt die Viskosität des Hydraulikmediums während der Arbeitsdauer des Schraubers annähernd konstant. Würde infolge einer Temperaturerwärmung das Hydraulikmedium dünner werden, dann besteht die Gefahr, daß der zum Öffnen der Ventilkugel 46 notwendige Solldruck in der Zylinderkammer 24′ während des Schraubvorganges nicht erreicht wird, so daß der Schrauber auch nicht automatisch abgeschaltet wird. Da der Schrauber jedoch mit einer in bezug auf die Erwärmung des Hydraulikmediums optimalen Schlagzahl arbeitet, bleibt die Viskosität des Hydraulikmediums annähernd konstant, so daß mit Sicherheit der Schrauber beim vorgegebenen Drehmoment abschaltet.In the housing part 16 there are two compensating bores 60 and 61 (FIG. 2) in a reinforced wall area, which are also filled with the hydraulic medium. Both compensation bores 60, 61 are connected to one another, while the compensating bore 60 is also connected to the cylinder space 24 via a bore 62. The compensation bores 60, 61 can receive hydraulic medium from the cylinder space 24 if it expands as a result of an increase in temperature. In addition, losses in hydraulic medium can be compensated for by leaks via the compensating holes. A piston 63 is screwed into the compensating bore 60 at one end (FIG. 1). In the compensating bore 61, a further piston (not shown) is provided at the opposite end, which closes this compensating bore at the free end. One compensating bore 60 is completely filled with hydraulic medium, while the other compensating bore is only partially filled with the hydraulic medium. Depending on the amount of hydraulic medium in the two compensating bores, the piston (not shown) of one compensating bore can move in accordance with the amount of hydraulic medium in this bore. In the described hydraulic impulse screwdriver, the sealing conditions between the output shaft 19 and the housing part 16 do not change when working with the screwdriver, because the automatic shutdown of the screwdriver is achieved via the torque setting device 41 accommodated in the output shaft. This means that this screwdriver works with the same impact frequency regardless of whether soft or hard parts are to be screwed together. As a result, the impact frequency of the striking mechanism 4 can be kept at a favorable value with the screwdriver, at which a temperature increase of the hydraulic medium does not occur or only occurs very little. As a result, the viscosity of the hydraulic medium remains almost constant during the working time of the screwdriver. Would the hydraulic medium become thinner due to a temperature rise, then there is a risk that the required pressure to open the valve ball 46 in the cylinder chamber 24 'is not reached during the screwing process, so that the screwdriver is also not automatically switched off. However, since the screwdriver works with an optimal number of strokes in relation to the heating of the hydraulic medium, the viscosity of the hydraulic medium remains approximately constant, so that the screwdriver switches off at the specified torque with certainty.

Um die Erwärmung des Hydraulikmediums weiter zu verringern, ist der Ringspalt 30 zwischen dem Schraubergehäuse 1 und dem Halteteil 20 vorgesehen. Der Druckluftmotor 3 erzeugt einen Luftstrom, der über die Wälzlager 13, 32 in den Ringspalt 30 gelangen kann. Da er sehr schmal ist, in der Größenordnung von nur einigen zehntel Millimetern liegt, strömt die Luft mit einer verhältnismäßig hohen Geschwindigkeit durch diesen Ringraum 30 und kühlt somit intensiv den Halteteil 20 und damit auch den Zylinderteil 16. Die Luft strömt dann nach vorne über das Wälzlager 31 und die Durchtrittsstelle für die Abtriebswelle 19 aus dem Schraubergehäuse 1. Selbstverständlich ist es möglich, für die Kühlluft auch zusätzliche Nuten im Halteteil 20 zur Oberflächenvergrößerung vorzusehen.In order to further reduce the heating of the hydraulic medium, the annular gap 30 is provided between the screw housing 1 and the holding part 20. The compressed air motor 3 generates an air flow which can reach the annular gap 30 via the roller bearings 13, 32. Since it is very narrow, of the order of magnitude of only a few tenths of a millimeter, the air flows through this annular space 30 at a relatively high speed and thus intensively cools the holding part 20 and thus also the cylinder part 16. The air then flows forward over it Rolling bearing 31 and the passage point for the output shaft 19 from the screw housing 1. Of course, it is also possible to provide additional grooves in the holding part 20 for increasing the surface area for the cooling air.

Claims (11)

  1. Hydraulically impulsed screwdriver with a compressed-air motor (3) as the drive and a hydraulic striking mechanism (4) consisting of a cylinder connected in a non-rotary manner to a motor shaft (9) and an output shaft (19) able to rotate relative to the cylinder, which penetrates the cylinder, lies eccentrically with respect to the cylinder axis and comprises a bar (26), which bears under spring force against the inner wall (28) of the cylinder, and with a switching-off device for the screwdriver, which consists of a valve (10) disposed in the compressed air line to the motor (3), which valve, by way of an adjusting rod (55) disposed centrally in the motor shaft (9), defines a pressure chamber, which is connected by way of an adjustable pressure relief valve (45, 46) to one cylinder chamber of the cylinder, which is under pressure at the time of rotation of the motor shaft (9), the pressure relief valve (45, 46) being located in a bore (44, 56) on the output side, into which an adjusting screw (42) is rotated, by which the contact pressure of the valve member (46), opening towards the pressure chamber, on a valve seat is adjustable, characterised in that the pressure chamber lies in a central continuous bore (44, 56) of the output shaft (19) and the pressure relief valve is located in this central bore, the adjusting screw being axially accessible from the end of the output shaft (19) holding the screwing tool.
  2. Screwdriver according to Claim 1, characterised in that the valve seat (45) is provided at the end of the adjusting screw (42) lying in the bore (44, 56) and opening out in the valve seat (45) is a valve bore (53) connected by a line to the cylinder chamber (24).
  3. Screwdriver according to Claim 2, characterised in that the valve bore (53) extends centrally in the adjusting screw (42).
  4. Screwdriver according to Claim 2 or 3, characterised in that the adjusting screw (42) is surrounded over part of its length by an annular chamber (49), which is surrounded radially on the outside by the wall of the bore (44) of the drive shaft (19) and is connected to the cylinder chamber (24) and the valve bore (53).
  5. Screwdriver according to Claim 4, characterised in that the cylinder chamber (24') which is under pressure upon the application of a torque to the output shaft (19), is connected by way of the annular chamber (49) to the valve bore (53).
  6. Screwdriver according to one of Claims 1 to 4, characterised in that during the release of screws or nuts, the cylinder chamber (24''), which is under pressure, is connected by a line to the part of the bore (44) of the output shaft (19) located between the pressure relief valve (45, 46) and the adjusting rod end (54).
  7. Screwdriver according to Claim 6, characterised in that the cylinder chamber (24'') is connected by way of at least one bore (59) in the output shaft (19) to its central bore (44).
  8. Screwdriver according to one of Claims 1 to 7, characterised in that the cylinder chamber (24) is connected to at least one hydraulic medium reservoir (60, 61).
  9. Screwdriver according to Claim 8, characterised in that the hydraulic medium reservoir (60, 61) is provided in the cylinder (14, 16, 17).
  10. Screwdriver according to one of Claims 1 to 9, characterised in that cooling air circulates at least partly around the cylinder (14, 16, 17), which cooling air preferably flows in an annular chamber (30) between the cylinder (14, 16, 17) and the screwdriver casing (1).
  11. Screwdriver according to Claim 10, characterised in that the cooling air is produced by the rotating compressed-air motor (3).
EP88107194A 1987-05-26 1988-05-05 Hydraulically impulsed screwdriver Expired - Lifetime EP0292752B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873717630 DE3717630A1 (en) 1987-05-26 1987-05-26 HYDRO IMPULSE SCREWDRIVER
DE3717630 1987-05-26

Publications (3)

Publication Number Publication Date
EP0292752A2 EP0292752A2 (en) 1988-11-30
EP0292752A3 EP0292752A3 (en) 1990-01-24
EP0292752B1 true EP0292752B1 (en) 1994-04-13

Family

ID=6328388

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88107194A Expired - Lifetime EP0292752B1 (en) 1987-05-26 1988-05-05 Hydraulically impulsed screwdriver

Country Status (3)

Country Link
EP (1) EP0292752B1 (en)
DE (2) DE3717630A1 (en)
ES (1) ES2050676T3 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0699508A1 (en) 1994-08-18 1996-03-06 Cooper Industries Inc. Hydraulic impact screwdriver especially for tightening threaded connection

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3931634A1 (en) * 1989-09-22 1991-04-04 Telefunken Electronic Gmbh SEMICONDUCTOR COMPONENT
DE4218816C2 (en) * 1992-06-06 2002-09-05 Cooper Power Tools Gmbh & Co Hydro pulse tools
US5421240A (en) * 1993-08-06 1995-06-06 Fuji Kuuki Kabushiki Kaisha Autoshut-off device for oil pressure type pulse wrench
EP1920887B1 (en) 2006-11-13 2009-12-23 Cooper Power Tools GmbH & Co. Tool with hydraulic percussion mechanism
DE202013000454U1 (en) 2013-01-17 2013-10-07 Michaela Harth Hazmat warning sign

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3334487A (en) * 1965-09-07 1967-08-08 Ingersoll Rand Co Impulse tool with improved cut-off device
SE343231B (en) * 1969-02-28 1972-03-06 Atlas Copco Ab
EP0070325B1 (en) * 1981-07-17 1985-06-12 Giken Kogyo Kabushiki Kaisha Fluid impulse torque tool
DE3347016A1 (en) * 1983-12-24 1985-07-18 Bijon 7433 Dettingen Sarkar Impulse screwdriver
US4604943A (en) * 1985-02-04 1986-08-12 Ingersoll-Rand Company Impulse tool having shut off system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0699508A1 (en) 1994-08-18 1996-03-06 Cooper Industries Inc. Hydraulic impact screwdriver especially for tightening threaded connection
US5567886A (en) * 1994-08-18 1996-10-22 Cooper Industries, Inc. Hydraulic impulse screwdriver particularly for tightening screw connections

Also Published As

Publication number Publication date
EP0292752A2 (en) 1988-11-30
EP0292752A3 (en) 1990-01-24
ES2050676T3 (en) 1994-06-01
DE3717630A1 (en) 1988-12-15
DE3889006D1 (en) 1994-05-19

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