Patent GB-1335690-A (GB)
Title: Vehicle change-speed transmission
IPC: F16H61/30
Filed: 1970-11-02
Abstract: 1335690 Change-speed control AISIN SEIKI KK 2 Nov 1970 [31 Oct 1969 (5)] 52098/70 Heading F2D A vehicle change-speed transmission includes a cam selector disc 178, which is turned stepwise by an hydraulic motor 172 controlled by a valve 154, which, to change the ratio, is shifted by an hydraulic signal 176 representing a vehicle condition such as vehicle speed and/or engine torque or torque demand, and is returned to its initial position after shift by the cam selector disc to prevent further movement of the selector disc by the motor. In addition a main clutch 12<SP>1</SP> is controlled by the same valve 154 to disengage and re-engage hydraulically during each shift. In the synchromeshed four speed and reverse gear (Fig. 1, not shown) the 1-2 and 3-4 shift forks carry pins 184, 183 engage cam slots in the selector disc 178 which is secured to a shaft 188, which is turned, to move the shift-forks sequentially in opposite directions from neutral, by supplying hydraulic pressure selectively to an upshift or downshift chamber 173, 175, Fig. 7, of the motor 172 on opposite sides of a piston vane 187 secured to the cam-shaft 188, for clockwise upshift steps or anticlockwise downshift steps. Automatic shift valve 154 is normally maintained in a central position, shown, by balanced springs at each end, to exhaust both up and downshift servo chambers 173, 175, and is moved right to pressurize the upshift chamber 173 and left the down 175, and is returned back to the central position by a peripheral cam surface on the selector disc 178, bearing on a right end plug 180. The rightward upshift steps of the shift-valve 154 are produced by outputspeed-reaponsive governor pressure 176 acting at 167, leftward downshift steps being by the right end governor-opposing spring 181 and end plug 180. Governor pressure 176 acts in four stages in each of which the pressure is maintained constant (Fig. 8, not shown). The pressure stages are produced by an output-rotated centrifugal governor valve 129 and a stationary regulator valve 201. Line pressure 37<SP>1</SP> is fed to governor and regulator valve ports 200, 202 through restrictors 192, 208. First stage, zero governor pressure, is produced at low speeds when the centrifugal spool 195 of the governor valve is held radially inwards (shown) by its spring, to exhaust the governor supply line 193 at port 196, so that the regulator supply can move the regulator spool fully right, exhausting governor pressure 176 through a line 206 and governor valve port 197. In second stage the governor valve spool 195 moves centrifugally outwards, closing the exhaust port 196 and a port 199. Pressure in the feed line 193 now acts through a line 209 on a differential land 210 of the regulator valve 201 causing it to regulate a second stage governor pressure 176. At a higher speed, for third stage, the governor valve spool 195 moves further out, supplying pressure 193 to the port 199 and thence through a line 207 to act on a differential land 211 of the regulator valve 201, thus increasing its regulated governor pressure 176. At a higher speed, for fourth stage, the governor valve spool 195 pressurizes the previously exhausting line 206 so that governor pressure 176 rises to full line pressure. Main clutch control.-The main clutch 12<SP>1</SP> is disengaged by supplying line pressure 134 to a clutch line 160 in the rightward position, shown, of a clutch valve 135, and engaged by exhausting the clutch-line 160 at 147 in its leftward position. Rightward movement of the clutch valve is effected by supplying pressure to its left end 138, or (in its left position) at 145 to between separate end plugs 142, 143, or at 146 to between the plug 143 and valve spool 144. Shift sequence. Neutral.-In N setting, shown, of a manual RND valve 35<SP>1</SP>, pressure 34<SP>1</SP>, 221 shifts rightwards a piston 223 of a neutral control unit 222, which moves the cam selector disc 178 axially against spring pressure, so that a peripheral cam surface 179a now bears on the end-plug 180 maintaining the shift valve 154 central with its supply port 155 closed and the gear in neutral. The clutch valve 135 is maintained right, as shown, and release pressure 34<SP>1</SP>, 134, 160 passes to the main clutch 12<SP>1</SP>. Start.-When the manual valve 35<SP>1</SP> is moved to D, the line 221 is exhausted so that the neutral control unit 222 permits the cam selector disc 178 to return axially to bring a cam surface 179b under the end-plug 180, which is thereby shifted left to cause the shift valve 154 to pressurize a downshift chamber 175 of the vane motor 172, causing the vane 187 and cam selector disc 178 to turn anticlockwise to select first ratio. At the same time exhaust of a line 137 by the manual valve 35<SP>1</SP> permits the clutch valve 135 to move left and exhaust the clutch release line 160, causing clutch engagement. Shift.-When governor pressure 136 is high enough (or engine torque pressure low enough) to overcome the spring 181, the shift-valve 154 moves right, pressurizing an upshift servo chamber 173 and, through a line 156, pressurizing between the plugs 142, 143 of the clutch valve 135 (in its left position), which is thereby moved right (position shown) to pressurize the clutch-release line 160. As the selector camshaft 188 turns clockwise, the peripheral cam 178 also turns and, through the contacting endplug 180, returns the shift-valve 154 to the central position shown, leaving the cam-shaft 188 in second ratio setting, and exhausting the upshift chamber 173, and, with it the line 156, permitting the clutch-valve 135 to return left, exhausting the clutch-release line 160 for reengagement of the main clutch. 2-3 and 3-4 upshifts follow an identical sequence as the governor pressure stages are able to move the shift valve 154 at increasing speeds. Downshifts are similar as the leftward spring 181 overcomes decreasing governor pressure. Reverse.-In R setting the manual valve 35<SP>1</SP> directly shifts the reverse selector rod 190 by pressurizing a line 139. When reverse is established, pressure 139 passes through a line 161 to shift the clutch-valve 135 left, exhausting the clutch-line 160 for engagement of the main clutch. Modification.-Fig. 3 (not shown) has the following differences from Fig. 7 above. The governor and regulator details are not shown. The manual valve in D setting pressurizes an additional line acting on a left end plug of the shift valve to cause that valve to introduce first ratio on entering D setting. The end-plugs 142, 143 are omitted from the clutch valve, the various lines being isolated by two-way ball check valves. The neutral piston 222 is omitted, the clutch being engaged in N setting and disengaged by pressure from the upshift servo chamber when the latter is pressurized for first ratio, the clutch being then re-engaged when that chamber is exhausted after shift.