Patent GB-1095344-A (GB)
IPC: E21B1/26
Abstract: 1,095,344. Clutch and brake control. REGIE NATIONALE DES USINES RENAULT. Feb. 5, 1965 [Feb. 14, 1964], No. 5223/65. Heading F2D. A ratio establishing clutch or brake servo 4 is controlled by a distributing valve 3 having differential lands 15, 8 in chambers 18, 17 permanently open to the pressure of a pump 5, chamber 18 being supplied through a restriction 21 and having an exhaust line 23 controlled by a solenoid-operated pilot valve 24. When the solenoid is energized valve 24 closes the exhaust line and valve 3 is shifted to the right so that the pump supplies to the servo cylinder 4. When the valve 24 is opened the valve 3 is shifted to the left until the land 15 blocks the exhaust line 23 sufficiently for the forces on the valve 3 to balance, in which position (shown) the servo cylinder is exhausted. In a modification the servo cylinder is supplied and exhausted in the left and right-hand positions of the valve 3. In a further modification, shown in Fig. 4, a distributing valve 45 has differential lands in a chamber 18<SP>2</SP> and an annular chamber 17<SP>2</SP>, the chamber 17<SP>2</SP> being directly connected to the pump 5 and the valve spool having a restricted bore 56, 55 leading from the chamber 17<SP>2</SP> to chamber 18<SP>2</SP> which has an exhaust line 23 controlled by a pilot valve 24. A three-speed and reverse control, see Fig. 5, is provided by clutch or brake servos El, E2, F1, F2, controlled by distributing valves D1- D3 and relay valves R1, R2. The distributing valves D1-D3 are controlled by solenoid pilot valves S1-S3, the associated distributing valve being open when the pilot valve is open. Liquid is supplied by a pump 60 which also supplies an hydraulic converter 101 of the transmission, the pressure of the pump being determined by a valve G loaded in accordance with the position of the accelerator pedal so as to increase the servo pressure with accelerator depression and being loaded by pressure in an annular chamber 99 when the pilot valve S2 is closed to augment the servo pressure for reverse drive. Neutral is obtained with the pilot valves S1-S3 closed, thus ensuring that the pump can produce an adequate delivery pressure even when the engine is idling. In neutral, servo F1 is pressurized and the other servos are exhausted, the pump delivery pressure supplied through a line 80 shifting the relay valve R1 to the left to open a passage through lines 79, 77 to the servo F1. For first gear pilot valves S1, S3 are closed and S2 opened so that servo El is energized through the valve D2, and valve D3 remaining closed the servo F1 remains pressurized. For second gear pilot valve S3 is open, valve S1 remaining closed, and the valve D3 is shifted to its lefthand position in which pump pressure is supplied through a line 75 to the left-hand end of relay valve R1 which is thereby shifted to the right to exhaust the servo F1. Valve D1 is in its closed position in which a line 71 is exhausted so that relay valve R2 is in its left-hand position and liquid is supplied from the line 75 to the servo F2. The relay valve R1 ensures that the servo F2 is pressurized before servo F1 is exhausted. Servo E1 remains pressurized. For third gear all the pilot valves are open, servo E1 remains pressurized, relay valve R2 is shifted to the left by pressure admitted to the line 71 through valve D1, so that servo E2 is pressurized via line 71 and servo F2 is exhausted, the valve R2 ensuring pressurizing of the servo E2 before the servo F2 is exhausted. For reverse valves S2 and S3 are closed so that servos E2 and Fl are subjected to augmented pressure.