WO1996041701A1 - Portable screw or nut driver - Google Patents

Portable screw or nut driver

Info

Publication number
WO1996041701A1
WO1996041701A1 PCT/SE1996/000764 SE9600764W WO1996041701A1 WO 1996041701 A1 WO1996041701 A1 WO 1996041701A1 SE 9600764 W SE9600764 W SE 9600764W WO 1996041701 A1 WO1996041701 A1 WO 1996041701A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
handgrip
motor
tool housing
tool
device according
Prior art date
Application number
PCT/SE1996/000764
Other languages
French (fr)
Inventor
David Crafoord
John Grieves
Olle Torgny
Thomas Nilsson
Mikael Bergkvigt
Original Assignee
Ergonomi Design Gruppen 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

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25BTOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
    • B25B21/00Portable power-driven screw or nut setting or loosening tools; Attachments for drilling apparatus serving the same purpose
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B25HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25FCOMBINATION 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
    • B25F5/00Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • B25F5/02Construction of casings, bodies or handles

Abstract

The invention concerns a portable screw or nut driver (1) including a tool housing (2) which encloses a drive motor (8) and a transmission (9) which is connected thereto, a pistol type handgrip (3) and an output tool shaft (5) for rotating movement, wherein the drive motor (8) is placed axially behind the transmission (9) as seen from the output shaft. The invention is distinguished by: that the motor axis (11) and the tool housing (2) in the area of the motor are displaced in the direction from the handgrip (3) with respect to the output axis (5); and that the handgrip (3) is connected to the tool housing in the area between the motor and the transmission, whereby the handgrip (12) for a hand enclosing the handgrip on the side which is limited sidewards by the tool housing in the area of the motor likewise is displaced in the above direction so that said handgrip (12) comes closer to the extended output axis (5).

Description

PORTABLE SCREW OR NUT DRIVER

The invention concerns a portable screw or nut driver according to the preamble of claim 1.

Tools of this kind have up to now been badly adapted to a user as to ergonomics, i.a. because of the fact that their construction and control system cause that relatively great torque impulses appear and are transferred to the holder hand of the user. The torque impulses are transferred to the user because of the fact that the conventional pistol type grip is badly adapted to protect the user therefrom. The occurrence of torque impulses which are transferable to the user are greatly dependent upon time-consuming processes, e.g. prolonged tool braking upon shut down.

It is an aim of this invention according to a first aspect to reduce the impact of such torque impulses on a hand of a user and according to a second aspect of the invention also to reduce the transferable torque impulses emanating from the screw driver.

According to the first aspect of the invention the above problems in a screw driver according to the above are solved by the features of claim 1.

Hereby it is surprisingly achieved that pulling impulses appearing at torque growth or tool shut down, result in reduced impact to the hand of the user. By the handgrip being displaced closer to the extension of the output axis, and possibly even intersecting this axis, it is achieved that the harmful impact to the hand, the wrist and the forearm is reduced. As an extra effect it is also achieved that it will be essentially easier for the user to control and guide the driver towards the screw/nut to be driven since the output axis comes closer to the imaginary axis of the forearm of the user. Also this effect enhances the function of the tool and reduces strain in use and thus also a risk of the user being injured. 3y claim 2 it is achieved according to the second aspect of the invention, that transferable torque impulses are reduced since the time of the braking process is reduced.

By using a sensor device which is arranged in accordance with claim 3 it is achieved that also possible deformation of the house may be tolerated without thereby reducing the accuracy. This way a considerably weaker housing and weaker fastenings etc may be used which result in reduced weight of the resulting tool and thereby reduced strain to the user.

The feature according to claim 4 accentuates the usefulness of the tool for screw fastenings of different degree of hardness.

Claim 6 and particularly claim 7 concerns preferred embodiments of the tool housing giving the possibility to construct the device according to the invention as a light-weight tool.

The feature according to claim 8 gives a possibility to hold the tool in such a way that possible remaining impulse forces can be taken up with reduced harmful impact.

The invention will now be described on hand of an embodiment and with reference to the annexed drawing, wherein:

Fig. 1 shows diagrammatically in section a screw driver according to the invention.

The screw driver of Fig. 1 is a preferred embodiment of the invention and includes a tool housing 2, a handgrip 3 adjoining centrally thereto and a counter hold body 4, which on the side opposing the tool housing is provided with a (second) actuator button 7 to be used for example when holding the tool with two hands. The output axis is indicated with 5 and the pistol type actuator button 6. The tool housing contains a drive motor 8, which is arranged behind a transmission 9 and the motor axis is displaced the distance L in the direction from the handgrip with respect to the output axis by an arrangement with intermediate gear wheels 10 between the motor and the transmission. This displacement results in corresponding displacement of the portion of the tool housing which is in the area of the motor and thus that the pistol type hand grip (at 12) comes closer to the output axis and is possibly intersected by its extension in the rearward direction. Because of this displacement, a user holding the tool is subjected to reduced impact from harmful pulls that may appear at the same time as he is able to get better control over the alignment the tool, which in turn leads to more relaxed handling thereof.

The per see previously known transmission 9 is fastened to the front end of the tool housing over a sensor device 13 for sensing torque. In order to make it possible to use a tool housing 2 which is shaped as a shell structure from a thin, light-weight composite material, the sensor device 13 is divided at 14 in two parts which are rigidly connected to the tool housing and transmission respectively. The first of these parts is a defor able element which is shaped as a circular cylindric shell structure body having strain gauges fastened thereon and slot shaped cut-outs in order to increase its disposition for deformation. The parts are arranged so as to be rigidly joined to each other in a rotational direction but allowing a limited mutual axial movement. This way deformations of the housing 2 occurring during driving has reduced impact on the measurement results.

The control system inside the tool is comprised of a micro computer circuit, which controls feed supply to the driving motor so as to reverse the motor for allowing as effective braking as possible when a desired torque is obtained. Hereby so called power transistors are preferably used because of i.a. weight and space saving reasons. Possible after-running due to inertia of rotating parts is hereby considered.

The said circuit preferably contains a memory storing information about functions of torque and torque growth dependent upon driving time for different types of for example hard or soft fastenings. When calculating the time of stopping for the device, the received values are compared with the stored information for delivering a control signal which is related thereto to the feed circuit.

In order to avoid the need of torque adjustment means, the tool is preferably provided with means for sensing final torque information which is present on the different tool bits, said means being located in the tool bit receiving area. The information may be transferred magnetically, optically or mechanically. In case of mechanical sensing a preferred solution is based on each type of tool bit being provided with a unique axial length of the portion which is received in the tool bit holder. This may be realized by using a sensing rod centrally through the output shaft for sensing an axial protrusion, an axial hole of the like in the respective tool bit. The rod in turn effects a tool bit sensor 15, which is arranged axially behind the transmission. This solution is possible because of the displacement of the motor axis according to the above which allows the presence of the necessary space for said tool bit sensor.

For verifying that a fastening has been driven to the prescribed torque, accurate driving is verified by a quality signal.

Finally, it is important for avoiding transferable pulls that sufficient energy is transferred to the motor in such a way that the process is as fast as desired. In case the tool is battery operated the control system therefore emits a warning signal indicating too low battery charge level as seen from this aspect.

Claims

C L I M S
1. Portable screw or nut driver (1) including a tool housing (2) which encloses a drive motor (8) and a transmission (9) which is connected thereto, a pistol type handgrip (3) and an output tool shaft (5) for rotating movement, wherein the drive motor (8) is placed axially behind the transmission (9) as seen from the output shaft, c h a r a c t e r i z e d in
- that the motor axis (11) and the tool housing (2) in the area of the motor are displaced in the direction from the handgrip (3) with respect to the output axis (5) , and
- that the handgrip (3) is connected to the tool housing in the area between the motor and the transmission,
whereby the handgrip (12) for a hand enclosing the handgrip on the side which is limited sidewards by the tool housing in the area of the motor likewise is displaced in the above direction so that said handgrip (12) comes closer to the extended output axis
(5).
2. Device according to claim 1 further including a control circuit which computes signals emanating from a sensor device inside the housing, which signals are representative of driving torque for controlling the driving process, and a control circuit which computes said signals for controlling the driving process, c h a r a c t e r i z e d in that said control circuit is arranged to reverse the motor (8) so as to brake to essentially immediate stop at the end of the driving cycle in order to thereby reduce the occurrence of pulling impulses.
3. Device according to claim 2, c h a r a c t e r i z e d in a sensor device (13) which is rigidly connected to a part of the transmission (9) as well as to the housing (2) in a rotational direction, and sensor means arranged thereon for sensing deformation thereof to emit signals representative of this deformation to the control circuit, wherein the sensor device includes two parts (at 14) , one of which being a deformable element, which are connected so as to allow an essentially free mutual movement in an axial direction within a limited interval between the two parts so as to prevent that possible deformation of the housing (2) have influence on the signals from the sensor device.
4. Device according to claim 2 or 3, c h a r a c t e r i z e d in that the control circuit is arranged to calculate torque growth as a function of driving time, said function being compared with torque growth functions for fastenings of different hardness being stored in a memory, whereby the moment for reversing the motor (8) is based on if the fastening to be driven is a hard or a soft fastening.
5. Device according to any of the claims 2 - 4, c h a r a c t e r i z e d by a quality control device which is arranged to deliver a signal after driving a fastening to a calculated torque.
6. Device according to any of the previous claims, c h a r a c t e r i z e d in that said tool housing (2) is integral with said handgrip (3) for forming a shell structure of a thin wall light weight composite material.
7. Device according to claim 6, c h a r a c t e r i z e d in that said shell construction is divided essentially perpendicular to the output axis (5) and through the handgrip.
8. Device according to any of the previous claims, c h a r a c t e r i z e d in that an elongate counter hold body (4) is arranged for taking up sideward directed force at the end of the handgrip (3) that is turned from the tool housing (2), the longitudinal axis thereof being essentially parallel to or converging in a forward direction with the axis of the tool housing.
PCT/SE1996/000764 1995-06-13 1996-06-12 Portable screw or nut driver WO1996041701A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
SE9502144 1995-06-13
SE9502144-0 1995-06-13

Publications (1)

Publication Number Publication Date
WO1996041701A1 true true WO1996041701A1 (en) 1996-12-27

Family

ID=20398600

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1996/000764 WO1996041701A1 (en) 1995-06-13 1996-06-12 Portable screw or nut driver

Country Status (1)

Country Link
WO (1) WO1996041701A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2839931A1 (en) * 2013-08-22 2015-02-25 Etablissements Georges Renault Electric screwdriver with controlled tightening

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3938787A1 (en) * 1989-11-23 1991-05-29 Gardner Denver Gmbh Electric screwdriver with torque-monitoring and braking circuits - has strain-guage torque meter providing continuous braking signal during rapid deceleration of motor
GB2239834A (en) * 1990-01-10 1991-07-17 Bahco Verktyg Ab Battery-driven handtools
DE4024031A1 (en) * 1990-07-28 1992-01-30 Reich Maschf Gmbh Karl Hand screwdriver unit
DE4225157A1 (en) * 1992-07-30 1994-02-03 Reich Maschf Gmbh Karl Electric screwdriver for self tapping screws having drill tip and threaded part - has electronic sensor which is activated depending on current taken so that rpm of electric motor is reduced whilst thread is screwed in

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3938787A1 (en) * 1989-11-23 1991-05-29 Gardner Denver Gmbh Electric screwdriver with torque-monitoring and braking circuits - has strain-guage torque meter providing continuous braking signal during rapid deceleration of motor
GB2239834A (en) * 1990-01-10 1991-07-17 Bahco Verktyg Ab Battery-driven handtools
DE4024031A1 (en) * 1990-07-28 1992-01-30 Reich Maschf Gmbh Karl Hand screwdriver unit
DE4225157A1 (en) * 1992-07-30 1994-02-03 Reich Maschf Gmbh Karl Electric screwdriver for self tapping screws having drill tip and threaded part - has electronic sensor which is activated depending on current taken so that rpm of electric motor is reduced whilst thread is screwed in

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2839931A1 (en) * 2013-08-22 2015-02-25 Etablissements Georges Renault Electric screwdriver with controlled tightening
FR3009803A1 (en) * 2013-08-22 2015-02-27 Renault Georges Ets Electric screwdriver enslaved clamping

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