Patent GB-315819-A (GB)
Title: Improvements in or relating to vibratory or reciprocating electric motors and cooling devices therefor
IPC: H02K9/04
Filed: 1929-02-04
Abstract: 315,819. Weyandt, C. S. July 19, 1928, [Convention date]. Reciprocating motors; cooling, and ventilating; supporting and mounting. - A reciprocating electric motor for a percussive rock drill, sieve, &c. is cooled by a fan &c. driven by an electric motor separate from the reciprocating motor. The invention is shown applied to a rock-drill. The field-magnets 5, 6, 7 consist of bundles of laminations arranged radially around a non-magnetic tube 8 so as to leave longitudinal air passages between them. They are enclosed in a magnetic casing 1 and provided with pole-pieces passing through slots in the tube 8. Wedge-shaped pieces 9 engage with the bevelled ends of the laminations and secure them in position. The armature consists of a magnetic core 4 furnished with guide rods 11 one of which strikes against the shank of the tool 15 and actuates it against a spring 22 and elastic end plate 24. The other rod 11 strikes against a stop 32 bearing on a laminated spring 33. Air is supplied by a fan 44 enclosed in a casing connected to the casing 1 by tubes 40 having a telescopic joint. The fan is driven by an alternating current motor 42, preferably of the squirrel cage or other commutatorless type, the spindle of which bears on a resilient member 43b. Preferably the reciprocating motor is supplied with low frequency current and the motor 42 with current of a higher frequency. Fig. 4 shows a diagram of connections for supplying several motors at once. High frequency current is supplied to three slip-rings a, b, c and low frequency to rings b, d, e. The rings a, c are connected to the contacts a<2>, c<2> of sockets 73 - - 76 and the rings b to the contacts b<2> of these sockets and the heating transformers 71 of eight valves A - - D, A<1> - - D'. The ring d is connected to the other terminal of the transformer 71 of the valves A - - D and to the contacts P. G of the socket 73 through the valves A and C and to those of the socket 74 through the valves B and D, the valves being connected up as shown so as to transmit the current to the contacts P, G alternately. The ring e is connected in a similar way to the sockets 75, 76 through the valves A<1> - - D'. The contacts P, G engage the contacts P', G<1> of a plug 77 which are connected to the windings 2, 3 of the reciprocating motor. The windings 2, 3 have also a common terminal connected through the contact b<3> of the plug 77 to the contact b<2> of the sockets 73 &c. The contact b<3> is also connected to the winding of the motor 42, as are contacts a<3>, c<3> of the plug 77 corresponding to contacts a<2>, c<2> of the plugs 73 &c. Fig. 8 shows an arrangement for obtaining high frequency current for the blower motor and low frequency current for the reciprocating motor from the same mains. For this purpose the conducter 102 of a three-phase main is connected to the common terminals of the windings 2, 3 of two reciprocating motors M', M<2> and to the midpoints of the primary windings of P, P<1> of two transformers. The conducter 103 is connected through oppositely-placed valves V and V<1> to the other ends of the windings 2, 3 of the motor M<2> and to the extremities of the transformer winding P, the conductor 104 being similarly connected through valves V<2>, V<3> to the transformer winding P<1>, and the motor M<1>. The secondaries S, S' of the transformers are connected to the stator winding s, s<1> of the blower motor M. Alternatively the windings S, S<1> may be connected to a second frequency-raising device which supplies the motor M. Disk or other rectifying devices may be substituted for the valves in the various arrangements described. In a modification the high and low frequency currents may be generated by separate generators 91, 92, Fig. 5, mounted on a single shaft driven by a prime mover such as an internal combustion engine enclosed in a hood 95, the whole being mounted on a frame 96 moving on rollers 99 running on rails and rollers 100 for running on a smooth surface.