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* GB780055 (A)
Description: GB780055 (A) ? 1957-07-31
Improvements in or relating to devices for rapidly braking reversibl...
reversed in said other direction before the engine has stopped. In
this case the starting motor is extremely heavily loade...
the section 33 leaves it about 300 before top dead centre upon
rotation of the cam disc of the engine in the direction of ...
connected to contacts 42 and 43. their other ends being earthed.
Between the contacts 42, 43 is disposed a contact 44 whic...
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780055

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780055

  1. 1. * GB780055 (A) Description: GB780055 (A) ? 1957-07-31 Improvements in or relating to devices for rapidly braking reversible internal combustion engines Description of GB780055 (A) PATENT SPECIFICATION Date of Application and filing Complete Specification: Oct. 18, 1955. Application made in Germany on Oct. 23, 1954. Complete Specification Published: July 31, 1957. Index at acceptance:-Classes 7(4), B2D(10:11B); 7(5), B2F11G; International Classification:-FO2d, f, H02j. 780,055 No. 29642/55. and 38(4), A15B1. COMPLETE SPECIFICATION Improvements in or relating to Devices for Rapidly Braking Reversible Internal Combustion Engines We, ROBERT BoscHGMBH, a German i Company of 4, Breitscheidstrasse, StuttgartW, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - The present invention relates to engine braking and more particularly to a device for rapidly braking two-stroke internal combustion engines which are adapted to be optionally started and to run in either direction of rotation, under reversible spark ignition. The term "reversible ignition" as used herein and in the appended claims refers to ignition which may be changed over or reversed" when it is desired _to change the direction of running of the engine; this enables the ignition system to have a similar operative connection with the engine, relatively to the engine piston displacement, when running in either direction. In known systems including two-stroke internal combustion engines which are fitted with spark ignition and started by means of a reversible starting motor, it may happen when changing over from one direction of rotation to the other that the starting motor is already
  2. 2. reversed in said other direction before the engine has stopped. In this case the starting motor is extremely heavily loaded, having to oppose and neutralize the kinetic energy still remaining in the engine when the motor is reversed. According to the present invention a device for rapidly braking by means of an ignition pulse an engine adapted to be started in either direction and then to run in that direction under reversible spark ignition, includes two contact-breakers which are respectively associated with one or other of the two directions of rotation and are also associated with the ignition, either of said contact-breakers being optionally connectable by means of a change-over switch to a source of ignition [Price 316] current, and a control member driven by the engine and adapted to actuate the contactbreakers is so formed and disposed relatively to the contact-breakers that when the engine is running in a particular direction the contact-breaker associated with that direction will open at the most 35 before but not later than top dead centre, whilst the other contact-breaker will open at least 1600 before said top dead centre. 55 The present invention will now be further described by way of example with reference to the accompanying drawings, in which:Fig. 1 is a diagrammatic view of a twostroke internal combustion engine having a 60 separate reversible ignition system and a reversible starting motor; Figs. 2 and 3 diagrammatically illustrate the ignition system contact-breaker on an enlarged scale, in different positions; and 65 Fig. 4 shows a wiring diagram of a further development of the system. The two-stroke internal combustion engine shown in Fig. 1 is equipped with a sparking plug 11 which is supplied by the high 70 tension winding 12 of an ignition coil 13. One end of the primary winding 14 of the coil is connected by an ignition switch 15 with one terminal of an accumulator 16 whose other terminal is earthed. The other end of 75 the primary winding 14 is connected to one or other of two stationary contacts 19 and 20 by the switch member 17 of a change-over switch 18. A contact breaker lever 21 is connected to the contact 19; a second interrupter lever 22 is connected to the contact 20. These contact-breaker levers are respectively pivotally mounted on spindles 23 and 24, and respectively carry moving contacts 25 and 26. These moving contacts are operatively associated with fixed contacts 27 and 28 respectively; these fixed contacts are both earthed. Springs 29 and 30 respectively engage said contact-breaker levers and bias them towards a cam 32 fixed on the engine crank-shaft 31. 90 780,055 As may be seen more clearly in Fig. 2, the cam disc has a flattened section 33 with an included angle of about 1705, the so-called closure angle of the cam. The lever 21 is so arranged that
  3. 3. the section 33 leaves it about 300 before top dead centre upon rotation of the cam disc of the engine in the direction of the arrow A. At this point, the contacts 25, 27 will thus be opened. The other lever 22 is offset relative to the lever 21 by about 1300 in the opposite angular direction to the arrow A. Preferably the closure angle lies within the range of 1500 to 175 and the angular separation of the contact-breakers is at least 1200. To start the engine in the required direction of rotation a reversible electric starting motor 34 is used. The motor 34 can be connected to the battery 16 through a two-way switch 35. When this switch is in the position I the motor is connected for running clockwise and in the position II for running anticlockwise. The system operates in the following manner: Assuming that the engine is turning over in the direction of the arrow A (running anticlockwise), the switch member 17 of the change-over switch 18 is on contact 19 so that the lever 21 is connected to the ignition coil. The contact-breaker is opened as usual 300 before top dead centre, whereby the machine receives an ignition spark. When the driver wishes to drive the internal combustion engine in the opposite direc-35 tion, he places the switch member 17 on the contact 20. The contact lever 21 is thus replaced by the contact-lever 22 in the ignition circuit. If the internal combustion engine has not stopped at this time and, for example, makes another turning movement in the direction of the arrow A through top dead centre past the position shown in Fig. 2, the contact lever 22 moves on to the section 33 of the cam after about 600 engine rotation past the position of Fig. 2, i.e., 30 after top dead centre. The contacts 26, 28 are thus closed so that current flows from the battery through the primary winding 14 of the ignition coil. After a further rotation of 170 in the same direction, the contacts 26, 28 are opened and an ignition spark is produced. At this moment the engine piston is 1600 before top dead centre. The impulse produced by the combustion due to the ignition spark immediately brakes the engine and stops it. The driver now operates the twoway switch 35, moving it to the position I for clockwise running of the starting motor which starts the engine in the desired direction. In order to prevent reversing of the starting motor before the ignition change-over, it is expedient to control the two-way switch through the ignition change-over switch lever 17. Fig. 4 shows a wiring arrangement suitable for such an arrangement. The twoway switch 35 is actuated into one position or the other by the eneraisation of electromagnet 40 or 41 respectively. The energising windings of these electromagnets are respectively
  4. 4. connected to contacts 42 and 43. their other ends being earthed. Between the contacts 42, 43 is disposed a contact 44 which can be connected to the battery 16 through a press button 75 switch 45 used for actuating the starting motor. A switch bridge 46 connects the contact 44 with either contact 42 or with contact 43 according to which of its two operative positions the lever 17 is displaced, thus serving to reverse change-over switch 35 to reverse the engine ignition. The switch bridge 46 is secured on but insulated from the switch lever 17. * Sitemap * Accessibility * Legal notice * Terms of use * Last updated: 08.04.2015 * Worldwide Database * 5.8.23.4; 93p

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