Patent GB-891111-A (GB)
Title: Improvements in and relating to stepped-ratio change-speed gears
Filed: 1959-03-12
Abstract: 891,111. Change-speed control. ZAHNRADFABRIK FRIEDRICHSHAFEN A.G. March 12, 1959 [March 19, 1958], No. 8669/59. Class 80 (2). Change-speed control mechanism in a motor car is operated by oil under pressure fed through electromagnetically actuated valves to ratio selecting and establishing servomotors, the oil being put under pressure by a pump having an electrically initiated drive and a magnet stepping mechanism controlling the valves by manual actuation of an upshift press-button or a downshift pressbutton. Function summary.-A stepped ratio change-speed gear 12, Fig. 1, on a motor car preceded by the usual clutch has a cross-shift lever 130 and a ratio establishing lever 131 operated by hydraulic servo means 21 under the control of electromagnetic valves actuated for upshifts by successive depressions of a steering-column-mounted push-button 200, for downshifts by successive depressions of a push-button 201, for reverse by actuation of a push-button 203, and for direct restoration of neutral at any time by depression of a push-button 202. Indicating lamps 229 show which of the ratios, or neutral, has been established in the gearing. An output driven generator 215 is operative below 15 k.p.h. to cause downshifts in the gearing. The hydraulic servo means 21 is energized by a pump 25 driven from an electric motor 211 switched on only for ratio shifts, the pump 25 simultaneously supplying oil under pressure through pipes 28 to a servo 29 disengaging the main clutch by actuation of a lever 11. During ratio downshifts, the electric control means 20 energizes a solenoid 22 which reduces the setting of the throttle 13 of the car engine 10. The main clutch may be proceeded by a hydrodynamic clutch, for automatic starting. Hydraulic circuit.-The hydraulic servo 21, shown in two crosssections, Figs. 2, 3, receives oil through the pipe 30 from the pump 25 at a port 100, Fig. 2, whence it passes through passages 100<SP>1</SP>, 100<SP>11</SP> to a pressure relief valve 101 and return ports 102, 103. On starting the car, or restoring neutral in the gear, pressure oil is supplied through the port 30 and the port 100 to a groove 140, Fig. 3, closed by a valve 141 under the control of a solenoid 6. When the main clutch has been disengaged by the servo 29, a switch 232, Fig. 1, is closed, to energize the solenoid 6, Fig. 3, which opens the valve 141 so that oil under pressure can pass through a groove 142 to a port 104, Fig. 2. Oil under pressure passes thence through pipes 144, 145 to a space 123 between two ring pistons 146 slidably mounted upon the ratio establishing rod 131. The oil accordingly moves the ratio establishing rod 131 to the central, neutral, position shown. At the same time, oil under pressure in the pipes 144, 145 passes through a pipe 149 and a port 120 in the stem 108 of the establishing rod 131 to a port 148 and enters a space 105 at the end of a relay piston 106 biased rightwards by a spring. The relay piston 106 moves leftwards under oil pressure, and when it reaches the end of its travel, a pin 180 thereon closes a switch 112, Fig. 4, so that the neutral lamp 229, Fig. 1, lights up. In this position of the relay piston 106, Fig. 2, a port 110 open to the pipe 144 lies against a port 109 connected with a groove 113, Fig. 3, which communicates with valves 116, 117 under the control of solenoids 3, 4, and through a passage 118 with a valve 121 under the control of a solenoid 5. The closure of the switch 112, Fig. 4, simultaneously switches off the motor 211 driving the pump 25, so that no pressure is generated in the pipes 28, 30, &c. This condition always occurs when the car is started, or the gear is restored to neutral. By pressing the button 200, Fig. 1, for an upshift, the first ratio is established. The pump 211 operates so that the servo 29 disengages the main clutch. Simultaneously, the solenoid 5, Fig. 3, is energized to open the valve 121 so that oil under pressure from the pump, passing through the pipes 113 &c., passes through a port 124 to a space 126, Fig. 2, between two ring pistons 152, 153 upon the cross-shift rod 130. The port 124 also communicates with a pipe 128<SP>1</SP> which leads to a port 132 opened when the ratio selecting rod 130 is in the position shown. Oil pressure passes thence through pipes 133, 134 and a port (not shown) to a pipe 154, Fig. 3, leading to two valves 156, 158 controlled by solenoids 1, 2. For first ratio, the solenoid 1 is energized, so that the valve 156 is opened and oil under pressure passes therethrough to a passage 159, a pipe 160 and a cylinder 125, Fig. 2, which slides the ratio establishing rod 131 rightwards to establish the first ratio. A passage 161, Fig. 3, similarly connects the valve 158 to the space 150 at the right-hand end of the ratio establishing rod 131. Under the conditions described above, the oil under pressure slides the piston 146 rightwards and establishes the first ratio. Simultaneously, the rod 108 moves rightwards, so that a groove 120 therein coincides with ports 164, 165 through which oil under pressure from the pipes 144, 145, 149 passes to a pin 166 which closes a contact 127, Fig. 4, to light the lamp 229 showing that the first ratio has been established. Simultaneously, the switch 127 stops the motor 211 driving the pump 25. To establish the second ratio, the rod 131 is slidden to the left. To obtain a cross-shift for the selection of the third and fourth ratios, oil under pressure is admitted to the space 151 at the right-hand end of a ring piston 153 which then slides the selecting rod 130 leftwardly. The rod 131 is then slidden left or right, as before, to establish the third and fourth ratios. Electric circuit.-Closing the car ignition switch (not shown) connects a line 240, Fig. 4, to a source of current, thus energizing a line 241 leading through an opened holding relay 208 and a line 242 to a lamp 229 degrees, indicating that neutral is established, and also through the switch 112 operated by the relay 105, Fig. 2. Under these conditions, the electric motor 211 of the oil pump P is switched off, and the servo-mechanism is not under pressure. To obtain the first ratio, the push-button 200 is depressed. The positive line 240 is thereby connected through a rectifier 252 and a line 253 to a relay coil 205, which moves a switch 227 from the position shown to connect a relay coil 204 between the positive line 240 and an earth 255. Simultaneously, the switch 227 disconnects a multiple-arm rotary selector switch 228 from the earth 255. Energization of the relay coil 204 acts through a pawl mechanism 243 to step the rotary switch 228 one step in the clockwise direction, to the position corresponding to the first ratio. At the same time as this movement occurs, a switch 206 is closed by the relay 204 so that a relay 207 is connected between the positive line 240 and through a line 254 and the switch 227 to the earth 255. Energization of the relay 207 moves a switch 208 from the position shown so that current flows through the lines 240, 241 and the now closed switch to a relay 209 which closes a switch 210 and thus connects the pump drive motor 211 to a source of current. Accordingly, the pump P begins to operate. Simultaneously, closing the switch 210 connects the source of current through a line 249 to the rotary selector switch 228. By this time, the press-button 220 has been released, so that the relays 204, 205 have been de-energized. Accordingly, the solenoids 1, 5 are connected to the earth 255 through a line 244 and the switch 227. The other sides of the solenoids 1, 5 are connected through the rotary switch 228 to the positive line 249, and are energized to establish the first ratio as described above. The relay coil 207 is maintained energized by current flowing from the line 240, through the switch 208 to a line 245 and through a closed switch 127 to earth. When the main clutch has been disengaged by energization of the servomotor 29, the switch 232 is closed. The solenoid 6 is thereby energized and the selected first ratio established as described above. The relay coil 209 continues to receive current through the switch 208, so that the switch 210 is maintained closed. On completion of ratio establishment, the switch 127 is opened by the pin 166, Fig. 2, and the relay 207, Fig. 4, is therefore de-energized. Accordingly, the relay coil 209 is de-energized, and the switch 210 opens to stop operation of the motor drive pump 211. The switch 127 then closes again. The solenoids 1, 5, 6 become de-energized and the valves 156, 121, 141, Fig. 3, return to the positions shown. When the relay coil 207, Fig. 4, is de-energized, a lamp lights to show that the first ratio has been established. By further depression of the pushbutton 200, a shift is made up to the second ratio, and so on, to the fourth ratio. When the push-button 201 is depressed to initiate a ratio downshift, the positive line is connected through a rectifier 256 and the line 253 to the relay coil 205 which is, as before, energized, to actuate the switch 227 and disconnect the rotary switch 228 from the earth 255, simultaneously connecting a relay coil 204<SP>1</SP> to earth through the switch 227. Energization of the relay coil 204<SP>1</SP> acts through a pawl 247 to step the rotary switch 228 one step in the anti-clockwise direction, and simultaneously changes the state of the switch 223 to connect the earth 255 through lines 248, 254 to the relay coil 207. This actuates the switch 208 to energize the relay 209, and switch on the pump 211, as before. At the same time the rotary switch 228 receives current through the line 249 and passes it through contacts III, III<SP>1</SP> and the solenoids 1, 3 to the line 244, which is now connected to earth 255 through the switch 227, the push-button 201 having been released and the relay 205 de-energized. Following disengagement of the main clutch by the servo 29, the switch 2