GB1243745A - Improvements in or relating to change-speed gear transmissions - Google Patents

Abstract

1,243,745. Change-speed control. HONDA GIKEN KOGYO K.K. 7 Feb., 1969 [9 Feb., 1968], No. 6884/69. Heading F2D. In an automatic change-speed motor-vehicle transmission giving three forward speeds and reverse, ratio selecting clutches 12, 13 are respectively applied for second and third speed shifts by fluid pressure controlled by 1-2 and 2-3 shift valves 52, 42 actuated by opposing fluid-pressures sensitive respectively to output speed (governor pressure) and engine torquedemand (TV pressure). Function summary.-Drive range, D, setting of a manual valve 41 (Fig. 3, not shown), gives automatic shifts between all three forward ratios first being one-way, Figs. 4 and 5 (not shown) illustrating 2 and 3 settings for second and third ratio hold, a first ratio hold being effected with the valve 41 in setting 1. TV pressure is sensed by engine throttle setting. Gear arrangement.-The change-speed gear 5, incorporated in a compact unitary assembly with an engine 1, torque-converter 3 and differential gear 28, has parallel driving and driven shafts 6, 7 carrying two spaced pairs of meshing gears 14, 15 and 16, 17 selectively connected to the driving shaft 6 for second and third speed by the clutches 12, 13 respectively, and two further gear trains 24, 22 and 27, 25, 26 respectively engaged for first and reverse speed, on release of clutches 12, 13, by a sliding dog clutch 20 operated by a fluid pressure servo 50, the first speed gear 22 incorporating a one-way clutch 23 whereby it free-wheels in the higher speeds. Fluid pressure supply and regulation.-A single engine-driven pump 29 supplies the system, and its line pressure 31 is regulated by a control valve 39 responsive to the stator reaction force in the torque converter 3. Control pressures. Governor.-An output-shaft mounted centrifugal governor valve 37, 38 is supplied through a restrictor 36d with line pressure 31 in all settings; and supplies governor pressure to the manual valve 41 via a line 36. TV pressure, 35 is supplied by a TV valve 34 fed with line pressure 31, via line 32, and loaded between opposing springs by a lever 33 subject to engine throttle setting. Shift valves.-Differentially landed 1-2 and 2-3 shift valves 52, 42 are loaded rightwards for upshift by governor pressure 36 and leftwards for downshift by TV pressure 35. Shift-timing.-In D setting, the 1-2 valve 52 upshifts by supplying line pressure 31 from a line 49 through a line 46 to the apply chamber of the second-speed clutch 12, which picks up from the overrunning clutch 23 of first speed. For the 2-3 upshift the 2-3 valve 42 simultaneously supplies line pressure, via line 48, to the third-speed clutch 13 and exhausts to atmosphere the second-speed clutch 12. In first speed setting (I), the left-hand ends of both shift valves 42, 52 are vented to atmosphere, whereby both valves are maintained in their first positions to hold first speed In second speed setting (II), the left-hand end of the 2-3 shift valve 42 only is vented to atmosphere whereby the valve 42 is maintained in its first position to hold second speed. In third speed setting (III), the left-hand end of the 2-3 shift valve 42 is connected to line pressure 31, whereby the valve is moved to its second position to hold third speed In reverse speed setting (R), the lines 32, 49 and 51 are vented to atmosphere and line pressure 31 supplied to the left-hand side of the reverse-first engaging servo piston 50, whereby the sliding dog clutch 20 is rightwardly moved to disengage first speed and engage reverse, the servo piston-rod incorporating a groove for fluid pressure control (i.e. disengagement) of the main clutch 4 during first-reverse shift.