Patent GB-190401374-A (GB)
Title: An Improved Method of and Means of Regulating Electric Motors.
Inventor: LANG JOHAN GUSTAF VIKTOR
Filed: 1904-01-19
Granted: 1904-10-06
Abstract: 1374. Lang, J. G. V. Jan. 19. Motors, controlling.-A controlling-switch for two or more motors having their field windings capable of being changed from a series to a compound condition or vice versÔ, such as that described in Specification No. 329, A.D. 1903, is arranged so that the current from the power circuit is not interrupted while the changes are made. The invention is particularly applicable to motors of the kind employed for driving vehicles in which the motors act as generators when retarding the vehicles. A number of series field windings are either retained in, or introduced into, the circuit until the change is made, and are then either cut out or retained as part of the series field windings. This arrangement minimizes sparking at the contacts. This closed - circuit principle is applied throughout all the changes. The reversing and field change contacts are arranged on one cylinder which is automatically turned through a small angle by the main cylinder when the motion of the latter is reversed. It is capable of being turned independently through 180‹ to reverse the switch when the main cylinder is in the off' position. Means are provided for preventing the main cylinder from being turned until the reversion is complete. As shown in Fig. 1, the main cylinder A<x> is provided with contact-strips, to engage fixed contacts A<1>. The reversing and field change cylinder Bx is provided with sets of contacts b<1Î>, b<2Î> to engage fixed contacts B', and b<1>, b<2> to engage fixed contacts B'. The contacts b<1>, b<1Î> come into engagement when the contacts b<2>, b<2>x are disengaged. The fixed contacts A', B', B<2> are connected as shown through the armatures d<1>, d<2>, d<3>, d<4>, groups of series windings e<1>, e', e<3>, e<4>, and f, starting - resistance s, higher and lower field resistances f and f<2>, and shunt resistances w<1>, w<2>. The windings e<1>, e<2>, e3, e<4> are of such dimensions as to allow them to serve as series windings when connected in parallel, and as shunt windings when connected in series. When the windings e<1> &c. are in parallel, the motors work like series-wound motors, but, when they are in series, the motors work as compound-wound machines. In the initial position of the switch, the windings e<1> to e<4> are arranged in parallel with each other, and in series with the armatures d' to d' and the resistance s. As the cylinder A<x> is turned, the resistance s is short-circuited and the resistances f<1>, f<2> are successively placed in parallel with the windings e<1> to e<4>. The field of one motor is next strengthened by cutting out the resistance f<2>, and the other motor is successively short-circuited, disconnected, and arranged in parallel with the first motor, both motors being at full field strength. After inserting resistances, the armatures of the motors are successively arranged in parallel, the resistances f<1>, f<2> being first cut out, and then again arranged in parallel. On turning the cylinder A<x> back, the cylinder B<x> is first turned to bring the strips b<2>, b<2Î> into operation, thus throwing the coils f in series with the armatures and then arranging the coils e<1> &c. in series with each other and in parallel with the armatures. The armatures are then successively arranged in series. Resistances w<2> thrown in the shunt circuit during the intermediate steps are cut out, and one set of armatures is short-circuited and arranged in series with the other. The coils e<1> &c. of the other motor are short-circuited during this operation, and the resistances w<2> are thrown in. These are successively cut out, the shunt circuit is broken, the resistance s is thrown in, and the coils e &c. thrown in parallel. On turning the cylinder Ax backwards before it has rotated to its high-speed position, the cylinder B<x> is rotated to bring the motors to their compounding condition, when they act as generators and supply the main current. Figs. 3, 5, and 11 show the operating-mechanism of the cylinders. The contacts b<1>, b<2>, Fig. 11, are arranged on the cylinder B<x> so that the rotation through a small angle carries the other set of contacts into engagement, while the rotation through 180‹ reverses the contacts. The axis B<2Î> of the cylinder B<Î> carries two discs B<3>, B<4>, either of which can be secured to the axle by a clutch g operated by a lever G from a disc A<3> on the axis A<2> of the cylinder A<x>. At the 'off' position of the latter the end of the lever G enters a slot in the disc A<3>, and moves the clutch g out of engagement with the disc B<4> and into engagement with the disc B<3>. Simultaneously, projections g<6>, g<7> on the lever lock the disc B<3> and release the disc B'. The cylinder B<x> can now be turned independently so as to reverse the motor. The cylinder Ax is locked until the reversal is complete, by a lug on the lever G engaging between jaws a<1>, a<2> on the disc A<3>, the lever G being pressed endwise against the action of a spring g' by an eccentric portion of the disc B<3>. Pawls b<3>, b<4> prevent unintentional movement of the discs B<3>, B<4>. The cylinder B<x> is moved through its small angle by a pinion b engaged with racks H, I pressed by springs h<4>, i<4> into engagement. The rack H is formed with cheeks h engaging each side of a disc A<4> on the axle A<2>, and with a slot which engages teeth formed on the disc A<4> in positions corresponding to the speed notches, so that each reversal of the cylinder A<x> operates the rack and pinion b, and throws the motors into or out of the braking condition. The end of the rack I is turned down at i<1>, to engage a pin on a disc A<5> on the axle A<2>, so that, when the cylinder A<x> is in its 'off' position, the pin operates the rack and turns the cylinder Bx.