GB2113321A

GB2113321A - Electromagnetic clutch mechanism

Info

Publication number: GB2113321A
Application number: GB08233967A
Authority: GB
Inventors: Jan Pajgrt; Miroslav Malousek
Original assignee: VYZK VYVOJOVY USTAV; ZVS Vyzkumnevyvojovy ustav
Current assignee: VYZK VYVOJOVY USTAV; ZVS Vyzkumnevyvojovy ustav
Priority date: 1981-12-15
Filing date: 1982-11-29
Publication date: 1983-08-03
Also published as: CH660775A5; GB2113321B; DE3242313C2; ATA448482A; CS232675B1; AT387437B; DE3242313A1

Abstract

An electromagnetic clutch mechanism, particularly for a weaving machine, has a pair of electromagnets (20, 21) between which a friction disc (12) is arranged, which is mounted axially displaceably on an output shaft (8) which is mounted inside the magnetic clutch mechanism in a bearing (7). A respective rotor (5, 13) with preferably a friction lining (6, 14) and mounted on a shaft (4, 15), is associated with each electromagnet. Between the rotor and/or disc and its shaft (4, 8, 15) is arranged a bridge (25, 26) with high reluctance. <IMAGE>

Description

SPECIFICATION Electromagnetic clutch mechanism The present invention relates to an electromagnetic clutch mechanism, particularly for a weaving machine. Such a mechanism may comprise a friction disc coupled to an output shaft and arranged to be brought into driving engagement with an input shaft by electromagnets.

An electromagnetic clutch mechanism may have the output shaft mounted in a bearing, which is arranged near the friction disc. A problem exists in ensuring the accurate location of the output and input shafts. When a bearing is provided between the output and input shaft the manufacturing inaccuracies of the positioning of the separate shafts in the clutch mechanism are manifested leastmost.

The bearing represents in the whole system a joint. During operation of the clutch mechanism, when one of the electromagnets is engaged, the bearing of the output shaft is stressed by the magnetic leakage flux coming out of the electromagnet and flowing via rotor and bearing into a friction disc coupling suitably an entraining disc, and therefrom into the friction disc.

This magnetic leakage flux considerably reduces the efficiency of the clutch mechanism in the clutch part as well as in the brake part.

This reduced efficiency is to be compensated by enhancing the electric input both to the clutch and the brake part of the clutch mechanism. The magnetic leakage flux reduces simultaneously the lifetime of the bearing, particularly at higher operation speed of the clutch mechanism. The bridge arrangements of the invention help to reduce or eliminate this problem.

An electromagnetic clutch according to the present invention comprises a pair of electromagnets arranged to act on a rotatable friction disc axially displaceably mounted between the electromagnets, the disc being mounted to an output shaft so as to drive the shaft, a bearing being provided for the output shaft, a second shaft to which is fixedly mounted a first rotor carrying one of the electromagnets wherein the disc and /or rotor is connected to its shaft by means of a high reluctance bridge.

A further advantage of the electromagnetic clutch mechanism according to the present invention consists in a substantial reduction of the electric input necessary for both the clutch and the brake part of the clutch mechanism, and also, as proved by tests, a substantial enhancing of the lifetime of the output shaft bearing.

An electromagnetic clutch mechanism according to the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is an axial cross-section from the side of the clutch mechanism, and Figure 2 is a front view of a rotor of the mechanism of Fig. 1.

The electromagnetic clutch mechanism is provided with a housing 1 with a lid 2. In the lid 2, in bearings 3, is mounted control shaft 4, to which is fastened, inside housing 1, rotor 5, which is provided at its front part with an annular friction lining 6. At the end part of control shaft 4, another bearing 7 is situated, in which one end of output shaft 8 is mounted, of which the opposite end is mounted in a not represented bearing of a weaving machine. Bearing 7 makes possible minor deviations of the output shaft 8 in the whole system. Inside housing 1, a friction disc 1 2 of ferromagnetic material is mounted longitudinally displaceably, relative to output shaft 8, on transverse projections 11 provided on the periphery of entraining disc 10.The friction disc 1 2 is parallel to rotor 5, and the entraining disc 10 is mounted on output shaft 8 and is coupled to the shaft by pins 9. On the opposite side of friction disc 12, a second rotor 1 3 with a further annular friction lining 14 is arranged oppoiste to rotor 5. The second rotor 1 3 is fixed to a hollow shaft 15, which freeiy surrounds output shaft 8 and which is mounted at the bottom 1 6 of housing 1 in a system of bearings 1 7. The opposite end of hollow shaft 1 5 can be connected to some movable parts of the weaving machine, or possibly to its main shaft.One of the rotors 5 or 13, in this particular embodiment the second rotor 13, is provided on its circumference with a worm wheel 18, which is in engagement with a worm 1 9 connected to a not represented electric motor. Electromagnets 20, 21 with windings 22, 23 are respectively attached to rotors 5 and 1 3. One electromagnet 20 is fixed to lid 2 of housing 1, while the other electromagnet 21 is fixed to bottom 16 of housing 1.Each of the rotors 5, 13 is provided, at the level of the electromagnet 20, 21 attached thereto, with a discontinuous annular opening 24 with spoke-like portions 25 connecting mechanically the outer and inner parts of rotors 5, 1 3. Each of said rotors 5, 1 3 is connected to its shaft 4, 1 5 by means of a bridge with high reluctance, said bridge being formed, in the embodiment shown in Fig. 2, by spoke-like portions 26 connecting mechanically rotors 5, 1 3 with their shafts 4, 1 5. In the base of each portion 25, 26 openings 27 are made for enhancing reluctance. A bridge with high reluctance can be also formed of solid material with high reluctance, e.g. aluminium, copper, plastic material, or similar.

The electromagnetic clutch mechanism according to the present invention operates as follows: Upon supplying electric current to a not represented electric driving motor, control shaft 4 and, together therewith, first rotor 5 with friction lining 6 start rotating. Upon supplying electric current into the winding of the first electromagnet 20 attached thereto, friction disc 1 2 is attracted to the friction lining 6 of first rotor 5, and is entrained together therewith. The rotary motion of friction disc 1 2 is transmitted, by means of transverse projections 11, to the entraining disc 10 and therefrom, via pins 9, to the output shaft 8 of the clutch mechanism, and therefrom to the not represented main shaft of the weaving machine.

Upon supplying electric current into winding 22 of the first electromagnet 20, a magnetic field is formed which acts, on one hand, as the force attracting the friction disc 1 2 to the first rotor 5, forming on the other hand a magnetic leakage flux which is, however, intensely braked on its path by the bridge with high reluctance.

Upon supplying electric current into winding 23 of the second electromagnet 21, and simultaneously interrupting the supply to winding 22 of the first electromagnet 20, friction disc 1 2 is attracted to friction lining 14 of the second rotor 13, which is secured against rotary motion by self-locking of the worm wheel 18 with worm 1 9. In this manner, the rotary motion of output shaft 8 and the main shaft of the weaving machine is braked.

Also in that case, the magnetic leakage flux is intensely braked, this causing also a reduction of the necessary input and enhanding the efficiency of the actual magnetic operating flux, whilst also enhancing of the lifetime of bearing 7. Openings 27 also contribute in achieving these effects. These openings 27 diminish the magnetic intersection of portions 25, 26 without reducing their mechanical strength.

An analogous effect can be also obtained by modifying anologously the entraining disc 10.

Claims

1. An electromagnetic clutch mechanism, particularly for a weaving machine comprising a pair of electromagnets arranged to act on a rotatable friction disc axially displaceably mounted between the electromagnets, the disc being mounted to an output shaft so as to drive the shaft, a bearing being provided for the output shaft, a second shaft to which is fixedly mounted a first rotor carrying one of the electromagnets wherein the disc and/or rotor is connected to its shaft by means of a high reluctance bridge.

2. A mechanism as claimed in Claim 1 wherein the other electromagnet is mounted on a second rotor connected to a third shaft by means of a high reluctance bridge.

3. A mechanism as claimed in Claim 1 or 2 wherein a bearing is provided between the output and second shaft.

4. A mechanism as claimed in Claim 2 wherein the second rotor is provided with braking means.

5. A mechanism as claimed in Claim 2 or 4 wherein the third shaft is coaxial with the output shaft.

6. A mechanism as claimed in any one of Claims 1 to 5 wherein the friction disc is coupled to the output shaft by means of intercooperating projections between the disc and output shaft.

7. A mechanism as claimed in any one of Claims 1 to 6 wherein the bridge is formed by spoke-like portions which mechanically connect the or each rotor or disc to its shaft.

8. A mechanism as claimed in Claim 7 wherein in the base of each portion, openings are provided for enhancing reluctance.

9. A mechanism as claimed in any one of Claims 1 to 8 wherein the bridge is made of a high reluctance material preferably aluminium, copper or plastics material.

10. An electromagnetic clutch substantially as described with reference to the accompanying drawings.