Patent GB-1206221-A (GB)
Title: Improvements in hydraulic devices for controlling a stepped automatic transmission having three forward gears with under-torque shift and reverse
IPC: F16H61/62
Filed: 1968-03-29
Abstract: 1,206,221. Change speed control. REGIE NATIONALE DES USINES RENAULT, and AUTOMOBILES PEUGEOT. 29 March, 1968 [3 May, 1967], No. 15378/68. Heading F2D. An hydraulic device controls a stepped automatic transmission providing three forward gears with under-torque gear shift and one reverse gear such that failure of one element of the system automatically gives a lower reduction ratio. An eccentric gear pump 3, Fig. 1, supplies oil from reservoir 1 via an overpressure valve 5 through a constriction 25 to a port 24 of a pressure regulating valve 6 and also to a further port 18, a lubricating circuit G, a torque converter C, via a constriction 68 to the end chamber of an electrohydraulic valve 11 and to port 46 of a manual valve 10. The pressure regulating valve 6 controls the system pressure in dependence on the depression in the induction manifold 9 which is communicated through orifice 34<SP>1</SP> to the inside of a flexible sleeve 32, movements of which are transmitted through inter alia a rod 31 and springs 26, 27 to the valve member 16. In a modification, a sleeve (320), Fig. 5 (not shown), is secured to the rod 31 and to a vented casing (340) surrounding the sleeve 32. In operation, the fluid pressure at 24, or under some operative conditions also at 21, moves the valve member towards the left so that edge 36 opens port 18 until the leakage to the reservoir through port 19 balances the manifold pressure acting through the elastic connection and gives a stable operating pressure. The arrangement of dual springs 26, 27 gives a low operating pressure when the engine throttle is closed and a pressure which depends on the value of torque demand as the engine throttle is opened. The manual valve 10, which may have electrical automatic or semi-automatic operation, is associated with the valve 11 and controls either directly or through a relay valve 12 four hydraulic receivers R 1  . . . R 4 , of an epicyclic gear train (not described) consisting of friction devices capable of receiving a torque increasing in dependence on the fluid pressure supplied thereto. The valve 11 has electromagnetic valves 62, 63 to control the three positions of its slide valve member. When both valves 62, 63 are energized, ducts 64, 65 are closed by ball valves 66 to prevent controlled leakage. Surface 67 is acted on by the regulated pressure transmitted via constriction 68 and moves the valve member to the left until the surfaces 69 and 72 engage. When valve 63 alone is energized, surface 67 registers with port 73 to create a leakage at this port so that the fluid pressure acting on surface 67 is balanced by that acting on surface 69. When both valves 62, 63 are de-energized the surface 67 registers with port 74. Manual valve 10 has positions a . . . f corresponding to the following operative conditions:- (a) Imposed lowgear: Port 46 is connected with ports 48, 49 and 50 which supply respectively chamber 21, friction clutch R 1 , port 71 and port 76, whilst a port 54 vents the line 55 connected to the valves 11, 12. Valve member 58 is engaged with surface 72. Port 75 receives ambient pressure via port 54 and communicates with port 77, port 76 communicates with ports 78 and 103. Port 81 communicates with atmosphere via hole 82 and bore 83. Ports 103 and 105 communicate and the position of bearing 95 closes port 106. The pressure fluid whilst supplying receiver R 1  through line 52, keeps slide valve 90 in contact with end 104 and urges valve 91 to the left, thus reducing the free surface area between edge 109 of port 105 and the edge 110 of slide valve 91. A leakage output is produced at constriction 111 since port 106 is connected to atmosphere via port 54 and valve 91 assumes a balanced position in which a desired pressure is delivered to friction clutch R 3 . (b) Forbidden top gear: Port 46 supplies ports 48, 49 via groove 47, chamber 21 of the pressure regulating valve 6, friction clutch R 1 , and ports 71 and surface 67 of valve 11. The " forbidding " of top gear occurs when either or both electromagnetic valves 62 or 63 are energized which condition obtains in one or other of the following combinations:- (1) Low gear: Both valves 62, 63 are energized and surfaces 69, 72 are engaged. Ports 76, 78, 75, 77, 81 are vented to atmosphere and fluid is directed to friction clutch R 1 . (2) Intermediate gear: Valve 62 is energized and surface 67 registers with port 73. Ports 71, 81 interconnect with valve 12. Ports 79, 77, 75 and 76 are vented to atmosphere. Port 113, receives pressure from port 81 and connects via port 114 with friction clutch R 2  since valves 91 and 90 are engaged with the latter abutting end 104. Friction clutches R 3 , R 4  are vented to atmosphere. (c) Automatic or manual operation: The hydraulic connections are the same as in position (b) but de-energization of valves 62, 63 permits:- (1) Top gear: Valve 11 is in the position shown and ports 71, 81, 77 received pressure fluid which is directed to friction clutch R 4  and to port 117 via constriction 86. Friction clutch R 1  receives pressure fluid from port 49. Ports 76, 78, 79 are connected to ambient pressure. The areas of pistons 90, 91 are arranged so that these valves move to the left on attainment of a threshold pressure. When shifting from " intermediate " to " top " the pressure in chamber 101 and friction clutch R 4  has to reach a certain value before relay valve 12 cuts off the fluid to friction clutch R 2 . The reverse action is obtained on a down shift. (d) Neutral: This position only permits pressure fluid feed to chamber 21 via port 48 to permit the supply of fluid to torque converter circuit C and lubrication circuit G. Valves 62, 63 are energized to engage surfaces 69, 72 and ports 76, 71, 75, 81, 77, 78, 79 are connected to atmosphere so that fluid cannot flow beyond the valve 11. (e) Reverse: Bearing 39 isolates port 48 from port 46 and port 48 is vented to atmosphere. Port 54 is isolated from atmosphere by bearing 41 and is connected to port 46 via a duct 56. Chamber 21 is vented through port 48 and the pressure regulating valve 6 is balanced only by the pressure in chamber 24. Both valves 62, 63 are energized to engage surfaces 69 and 72. Pressure fluid is directed from port 54 to ports 117, 106 via ports 77, 75. Ports 79, 71, 81, 76 and 78 are vented to atmosphere. Valves 90, 91 are moved to the left and friction clutches R 3 , R 4  are supplied with pressure fluid. (f) Parking: Port 54 is vented to atmosphere and all other connections are in position (e). Valves 62 and 63 are energized with all ports of the hydro-electric valve vented to atmosphere. In a modification of the pressure regulating valve 6 a valve 206 supplies the lubricating circuit G and the hydraulic torque converter C in series in Fig. 3 or in parallel, Fig. 2 (not shown). The valve has three valve members 215, 216, 217 which are moved to the left by the pressure in chamber 224 during all gear shift operations so that edge 235 opens port 218 for pressures below a predetermined value. Increase supply pressure moves the valves 215, 216 and 217 to the left until the edge 222 uncovers port 219 connected by a duct to port 218 through which a regulated pressure is delivered to circuits G and C via groove 211 and port 231. The excess output is returned to the fluid reservoir via port 220.