Power wrench with a multi core cable connection means

Abstract: A power wrench provided with a torque and/or rotation angle sensing and signal generating means which are associated with the output spindle (14) of the wrench and supported on the wrench housing (10, 24), and a cable connection means (20) for connecting an electric multi core cable (19) to the sensing and signal generating means, which connection means (20) comprises a connection member (26) secured to the wrench housing (10, 24) and carrying a multi contact jack (27), and a multi contact cable connector plug (28) carried on the multi core cable (19), wherein the connection member (26) comprises an open ring element (29) encircling a wrench housing portion (24) and a longitudinally divided tubular coupling portion (30) which is formed with an internal socket (40) for retaining the multi contact jack (27) and an external thread (37) to be engaged by a threaded coupling sleeve (39) being a part of the cable connector plug (28).

Description: The invention relates to a power wrench according to the preamble of claim 1 (see, for example, DE-A-42 10 201), this power wrench being provided with sensing means for producing electric signals in response to the instantaneous value or values of one or more parameters like torque and angle of rotation significant for the tightening process performed by the wrench. In particular, the invention concerns a power wrench having torque and/or rotation angle sensing and signal generating means associated with the output spindle of the wrench, and a connection means for a multi core cable carried on the wrench housing and including on one hand a connection member secured on the housing and supporting a multi contact jack which communicates with the sensing and signal generating means, and on the other hand a multi contact cable connector plug. A power wrench of this type is previously disclosed in US Patent No. 5,181,575. In this prior art wrench a torque transducer is connected to a remotely located signal processing unit by means of an electric conductor leaving the wrench through the pistol handle. This means that the electric conductor is routed through the wrench housing and, accordingly, the wrench housing has to be designed to provide space for the conductor. In order to avoid the demand for a specially designed wrench housing enabling an internal routing of the signal conducting cables, there may be used an external cable connection mounted directly on the transducer part of the wrench housing. DE-A-42 10 201, which represents the most relevant prior art, discloses a power wrench of this type. A second handle is connected to a tubular front section of the housing, with one operation parameter sensing and signal generating means associated with the output spindle of the power wrench. A cable connection means is carried in this second handle and is arranged to connect these sensing and signal generating means to a multi-cove cable. The problem to be solved in such an application is to prevent the wrench from increasing in weight and size and to protect the connection means from mechanical damage. A power wrench according to this invention is defined in claim 1. The primary object of the invention is to accomplish a light, compact, uncomplicated and rugged cable connection which is easily mounted on the wrench housing and which provides a well protected multi contact connection between the cable and the tightening parameter sensing means, for instance a torque transducer and/or a rotation angle encoder. A further object of the invention is to provide a power wrench with a torque transducer and a cable connection means, wherein the cable connection means comprises a light signal delivering means for informing the operator of certain operational conditions of the power wrench. A preferred embodiment of the invention is hereinbelow described in detail with reference to the accompanying drawing figures. In the drawings: Fig.1 shows a side view of a power wrench according to the invention. Fig. 2 shows, on a larger scale and partly in section, the front part of the power wrench in Fig.1. Fig.3 shows parts of the cable connection in a disconnected condition. Fig.4 shows a front end view of the connection member occupying its normal closed position. Fig.5 shows the same view as Fig.4, but illustrates the connection member in its open mounting position. The power wrench shown in Fig.1 is a pistol type impulse wrench comprising a housing 10 with a handle 11, a rotation motor and a hydraulic impulse generator (not shown) located in the housing 10. The power wrench further comprises a power supply connection 12 communicating with the motor, a power control means maneuvered by a trigger button 13, and an output spindle 14 connected directly to the impulse generator and provided with a square end 15 for carrying a nut socket. Associated with the output spindle 14, the wrench is provided with a torque transducer 17 for producing electric signals in response to the magnitude of the pulsating torque delivered by the output spindle 14. The torque transducer is connected to a process controlling and monitoring unit 18 via a multi-core cable 19. The latter is connected to the wrench by means of a cable connection means 20. As shown in Fig. 2, the torque transducer 17 is of a contact free type including an output spindle portion 21 of a magnetostrictive material provided with groups of inclined surface grooves 22 arranged in a certain pattern, and exiting coils 23 disposed around this spindle portion 21. The exiting coils 23 are connected to the control and monitoring unit 18 via the connection means 20 and the cable 19. The transducer 17 is of a previously well known type which is described in for instance the above mentioned US Patent No. 5,181,575 as a part of a power wrench or in general in US Patent No. 4,933,580. The torque transducer is not in itself a part of this invention and is, therefore, not described in further detail. The housing 10 is provided with a tubular front section 24 which is rigidly secured to the housing 10 and which forms on its inside a support for the exiting coils 23. On its outside, the front section 24 forms a support for the cable connection means 20. On the outside of the front section 24, there are also mounted a number of electronic components for treating the signals delivered by the transducer 17 and for emitting light signals in response to the delivered signals corresponding to predetermined target values or not. These electronic components are not shown explicitly since they can be arranged in several alternative ways and do not by themselves form a part of the invention. The housing section 24 is clamped to the housing 10 and rotationally locked thereto by means of a lock pin 16. See Fig. 2. The housing section 24 is provided with a number of circumferentially spaced holes (not shown) for alternative engagement with the lock pin 16, which means that the housing section 24 may be secured to the housing 10 in a number of different angular positions. The cable connection means 20 comprises a connection member 26 for mounting on the housing front section 24, a multi-contact jack 27 and a multi-contact cable connector plug 28. The jack 27 is connected to the electronic components via a wiring 25. The connection member 26 is made of an electrically insulating and elastically resilient material like plastic and comprises an open ring element 29 and a coupling portion 30. The latter is divided along an axial plane into two halves 31, 32, and the ring element 29 has two end portions 33, 34 each carrying one of the coupling portion halves 31, 32. See Figs. 4 and 5. When mounted on the housing front portion 24, the connection member 26 is rotationally locked thereto by a radial lock pin 35. Accordingly, the connection member 26 is positively locked in a predetermined angular positions relative to the housing section 24. In order to retain properly the multi-contact jack 27 within the socket 40 before the coupling sleeve 39 is threadedly engaged with the coupling portion 30, the two halves 31,32 of the latter are clamped together by a transverse screw 36. On its outside, the coupling portion 30 is formed with a thread 37 for engagement with an internally threaded portion 38 of a coupling sleeve 39 of the cable connector plug 28. On its inside, the coupling portion 30 is formed with a socket means 40 for receiving and retaining the multi-contact jack 27. For making the light emitting electronic components visible from outside, the ring element 29 is provided with one or more radial through openings or windows 41. As an alternative to these openings 41, the ring element 29 may made of a light penetrating material, for instance an unpigmented plastic. In Fig 3, the connection member 26 is shown separated from the cable connector plug 28 as well as from the wrench housing. For illustration purposes, the connection member 26 still supports the jack 27, although the latter is disconnected from the wiring 25 and the electronic components carried on the housing section 24. Apart from the coupling sleeve 39, the cable connector plug 28 comprises a multi-contact unit 42 for engagement with the multi-contact jack 27 and a mounting sleeve 43 for retaining the contact unit 42. The mounting sleeve 43 consists of two semi-tubular shells 46,47 which together form an internal socket 48 for supporting the contact unit 42. The shells 46,47 also form together an external annular shoulder 50 to be engaged by an internal shoulder 49 in the coupling sleeve 39 for accomplishing an axial clamping force between the connector plug 28 and the connection member 26. The shells 46, 47 are kept together by a retaining sleeve 52. Moreover, the coupling sleeve 39 is formed with a tubular skirt portion 51 which extends rearwardly from the threaded portion 38 and the internal shoulder 49 to form a protective cover around the contact unit 42 and the closest part of the cable 19. This end part of the cable 19 is also covered by a resilient tubing 45 for protecting the cable 19 against mechanical wear. For mounting the connection member 26 on the front housing section 24, the connection member 26 has to be "opened", i.e. the two connection portion halves have to be elastically bent apart as illustrated in Fig. 5. The reason for that is to accomplish an easier mounting on the housing. The most important reason, however, is to be able to pre-mount the coils with the electronic components and the wiring 25 on the housing portion 24 together with the contact jack 27 before the connection member 26 is fitted, because it would be very difficult to connect the wiring 25 to the multi-contact jack 27, for instance by soldering, after mounting of the connection member 26 on the housing section 24. As the connection member 26 is properly mounted on the housing it is rotationally locked in a desired angular position by the radial pin 35, and the coupling portion halves 31,32 are clamped together by transverse screw 36. The cable connector plug 28 is assembled firstly by connecting, for instance by soldering, the cores of the cable 19 to the contact unit 42 and then by fixing the contact unit 42 between the two shells 46,47 forming the mounting sleeve 43 and introducing this assembly into the coupling sleeve 39. As the internal shoulder 49 on the coupling sleeve 39 engages the external shoulder 50 on the mounting sleeve 43 an axial locking of the contact unit 42 is obtained. Putting together the contact unit 42 and the multi-contact jack 27 and having the coupling sleeve 39 engage the thread 37 on the connection member 26 and to be tightened thereon, the cable connection is completed. For protecting the cores of the cable 19 from being exposed to tension strain, the cable 19 comprises a non-conductive tension cord (not shown), which is secured to the mounting sleeve 43 via radial openings 54,55 in the shells 46,47. Again, it is to be noted that the invention is not limited to a power wrench having just a torque transducer as in the above described example. The power wrench according to the invention may very well also comprise a rotation sensing means in the form of a rotation angle encoder associated with the output spindle. Also such a rotation angle sensing means generates electric signals which are communicated to the process controlling and monitoring unit via the multi-core cable and the multi-contact cable connection. Accordingly, signals representing parameters significant for the screw joint tightening process are communicated from the power wrench to a remotely located control and monitoring unit via a multi-core cable which is connectable to the wrench by means of a multi-contact cable connection as recited in the claims.

Claims: Power wrench, comprising a housing (10) with a tubular front section (24), a motor, an output spindle (14) connected to said motor, at least one operation parameter sensing and signal generating means associated with said output spindle (14), and a cable connection means (20) carried on said front section (24) and arranged to connect said at least one sensing and signal generating means to a multi-core cable (19), said cable connection means (20) comprises: a mounting member (26) secured to said front section (24) and supporting a multi-contact jack (27), and a multi-contact cable connector plug (28) which can be carried on said cable (19) and including a coupling sleeve (39) formed with an internal thread (38), characterized in that said mounting member (26) consists of an elastically resilient material and comprises: an open ring portion (29) with two end portions (33, 34) to be mounted around said front section (24), and a tubular coupling portion (30) extending laterally from said ring portion (29) and being divided along an axial plane into two halves (31,32), each of these two halves carried by respectively each end portion (33,34) said coupling portion halves (31,32) form together an internal socket (40) for receiving and retaining said multi-contact jack (27), and an external thread (37) for co-operation with said internal thread (38) of said coupling sleeve (39) at interconnection of said cable connector plug (28) and said mounting member (26), and said ring portion (29) and said coupling portion halves (31,32) are elastically expandable to facilitate assemblage of said connection means (20). Power wrench according to claim 1, wherein said coupling sleeve (39) comprises an internal shoulder (49) forming an axial support for components (46,47,48,42,43) of said connector plug (28), a tubular skirt portion (51) extending rearwardly from said threaded portion (38) and said internal shoulder (49) forming a mechanical protection means for componens (46,47,48,42,43) of said connector plug (28) and for an end part of said cable (19), when said cable (19) is connected to said connector plug (28). Power wrench according to claim 2, wherein said connector plug (28) comprises a multi-contact unit (42) which is electrically connectable to the cores of said cable (19), and a mounting sleeve (43) which is mechanically connectable to said cable (19) and consists of two semi-tubular shells (46,47) which together form an internal socket (48) for retaining said multi-contact unit (42), and an external shoulder (50) for positive engagement with said internal shoulder (49) of said coupling sleeve (39). Power wrench according to claim 2, wherein electronic signal treating components are located on the outside of said front section (24), and said open ring portion (29) forms a protective cover for said components. Power wrench according to claim 4, wherein said electronic components comprise one or more light emitting devices, said ring portion (29) is provided with one or more radial through openings (41), whereby said light emitting devices are visible from outside said ring portion (29) through said opening or openings (41). Power tool according to claim 4, wherein said electronic components comprise one or more light emitting devices, said ring portion (29) consists of a light penetrating resinous material through which said light emitting devices are visible from outside said ring portion (29). Power wrench according to anyone of claims 1 - 6, wherein said housing (10) is formed with a pistol type handle (11), said mounting member (26) is secured in a predetermined angular position relative to said front section (24), whereas said front section (24) is affixable to said housing (10) in a number of alternative angular positions for enabling alternative cable connection directions relative to the direction of said handle (11).

Inventors: SCHOEPS KNUT CHRISTIAN, SCHOEPS, KNUT CHRISTIAN
Applicants: ATLAS COPCO TOOLS AB
Application year: 1997
Main classification: B25B23
IPC codes: B25F5, B25B23, B25B21