Patent GB-756142-A (GB)
Title: New or improved means for regulating internal combustion engines
Inventor: FORSTER HANS-JOACHIM MAX
IPC: F02D29/00
Filed: 1951-11-08
Abstract: 756,142. Change-speed control. DAIMLER-BENZ AKT.-GES. Nov. 8, 1951, No. 26231/51. Addition to 718,016. Class 80(2) In the conjoint speed- and outputresponsive control for a stepwise changespeed gear for a vehicle described in the parent Specification, the speed- and outputresponsive members individually regulate pressures acting in opposition on differential selector slide-valves U1...U4 introducing the respective ratios, and the downward speed-responsive pressure is assisted by springs 174 &c., arranged in descending order of strength for successive ratios, that of the first speed valve U1 being the strongest, whereby that valve is the first to open on increase in speed. A resilient opposing pressure is also caused to act backwards on the operatorcontrolled output-demand member 101 at the downshift points whereby the operator can readily detect those points by feel. An engine braking range, with negative output selection is also provided. The four selector valves U1...U4 control pressure lines 137...140 leading respectively to cylinders introducing first, second, third and fourth speeds, the valve U4 also controlling a fifth speed line 141. A single continuously driven pump 106, with regulator R, or two pumps driven respectively by input and output shafts, supply the system, speed-responsive pressure being supplied to the upper faces of the selector valves U 1  &c., through a common line 117 and regulator-valve V loaded by a governor 115 driven by the output or other unspecified shaft. The springs 174 &c., assist the downward pressure on the selector valves U1 &c., and are graduated progressively weaker from that of the first valve U1. Output-responsive pressure acts upwardly on larger pistons of the selectorvalves U1, &c., through a common line 146 and regalator-valve V loaded by a goverator-controlled power-demand member 101. The latter 101 may be a pedal, which may control the engine output by adjusting a barometric capsule in the engine induction manifold acting on the engine throttle or other regulating member through a fluid servo in such a manner as to maintain constant output in any preset position, as described in the parent Specification. The gear-establishing lines 137...141 are supplied through the selector-valves U1 &c., from a common line 128 which communicates directly with the pump 106 through a manually-operable shut-off valve W. In second-speed, as shown, with the first selector valves U1 in its lower position and the others in their upper positions, the first, third, fourth and fifth speed lines 137, 139, 140 and 141 are exhausted at O through the valves U1; U3 and U2; U4 and U3; and U 4  respectively, whilst the second speed line 138 is pressurized through the valves U1 and U2. Increase in speed and/or reduction in power-demand causes corresponding changes in the opposing pressures whereby the next selector-valve U2 (i.e. the one with the next strongest spring) is moved downwards to exhaust the secondspeed line 138 at O and feed the third-speed line 139 from the line 128 through both selector-valves U2 and U3. Pressure passing through the space 156 of the valve U2, on its way to the third-speed line also, by acting on the differential pistons of the valve U2 increase the downward loading of the latter, whereby return upward movement of the valve for downshift can only occur at a correspondingly lower speed than the upshift. Further ascending speeds and, with reversed conditions, descending speeds are similarily automatically introduced. Downshifts are however accompanied by leftward movement of a detector piston 161, the stem 166 of which is thereby moved into abutting relationwith apart 167 of the power-demand pedal 101 which thus reacts on the operator to enable him to feel the downshift point. For this purpose the downshift-detector piston 161 is subjected to the same opposing pressures as the selector valves, V12 speed-responsive pressure in duct 169, assisted by a spring 165 acting rightwards and power-demand-responsive pressure in duct 159 acting leftwards on a piston 160 which acts on the detector piston 161 through two interposed pistons 162, 163 which, like the detector-piston 161 and an additional end-piston 164, communicate on their right faces with the respective lines 141, 140, 139 and 138 of the fifth, fourth, third and second speeds. These pistons 161... 164 are in descending order of magnitude, whereby the leftward thrust on the detector-piston 161 at the beginning of a downshift is progressively reduced with successive downshifts. The device to provide for an enginebraking range comprises a reversing rack- and-pinion and crank linkage 205, Fig. 2, between the operator-controlled power-demand lever 201 and the regulator-valve L, whereby backward movement y of the lever 201 (permitted by a supplementary lever 210) into the negative output range, acts in the same downshift-bias direction on the change-speed control as the normal forward movement y. The lever 201 operates the output control member through linkage 203 and the negative output range is indicated by a lamp 213. Reference has been directed by the Comptroller to Specification 522,881.