GB1450816A - Hydraulic apparatus - Google Patents

Abstract

1450816 Change-speed and clutch control KOMATSU SEISAKUSHO KK 10 Jan 1974 01286/74 Headings F2D and F2L In a regulator, for controlling the rate of increase in hydraulic pressure supplied by an inlet 4 through an outlet 5 to a servomotor a, actuating a ratio-establishing clutch in a motor vehicle transmission, comprising a pressure regulator 12, e.g. inside a control valve 2, and a quick-release valve 3 for rapid disengagement, the pressure peak which would otherwise occur in a known arrangement (Fig. 1, not shown) on completion of filling of the servomotor prior to the start of controlled rate of pressure increase, and due to the slow response of the pressure regulator valve, is avoided by providing the quick-release valve 3 with three positions, in the first of which (shown) the outlet 5 is closed from direct communication with an inletconnected passage 23 by a land 3a; the second position (left extreme) in which the passage 23 communicates directly with outlet 5; in both the first and second positions unrestricted communication is closed by either a land 3b or 3c between the inlet-fed passage 23 and a pressure loading chamber b of the regulator valve 12; and the third (intermediate) position in which 23 and b communicate without restriction. Inlet pressure 4 is supported constantly to the passage 23 through valve ports 9. Action is as follows. In the position of initial engagement inlet-fed pressure 4, 23, closed at land 3b (first position), passes through a restrictor 25 to the outlet 5 and also acts on the large land 3a to shift the quick-release valve 3 fully left, providing unrestricted inlet communication to the servomotor a which fills rapidly. Inlet pressure then building up in the passage 23 acts on the valve land 3c to shift the quick-release valve 3 towards the right, first through an intermediate (third) position, in which the inlet passage 23 communicates without restriction through ports 8, 15 with the loading chamber b of the pressure regulator 12, which then responds without delay and regulates through a control valve port 10 to exhaust 6 against a constant spring load 14, avoiding any pressure peaking. When the quick-release valve 3 reaches its extreme rightward (second) position, shown, communication between the inlet-fed passage 23 and the port 8 is cut-off by the land 3b and now the outlet 5 supplies the regulator load chamber b only through a bore 26 and restrictor 28 in the quick-release valve 3, and, through the same bore and a restrictor 27, feeds a chamber 19 loading leftwards the control valve 2 against a spring 11. Pressure still fed to the outlet through the restrictor 25, now increases at a rate controlled by the ability of the regulator valve 12 to uncover the exhaust port 10 on the control valve 2, which is itself being moved in the leftward, pressure-increase, direction by pressure 19, the rate of such movement, and hence the size of the restrictors 27, 28, determining the rate of pressure increase, which latter continues until the control valve 2 reaches the leftward limit of its travel, whereupon the outlet pressure remains constant. On release of pressure from the servo a, the quick-release valve 3 is moved rapidly left by pressure 23, closing the passage 23 at land 3c and exhausting the load chambers b and 19 at exhaust 6. The springs 11, 14 then return the control and regulator valves 2, 12 to the rightward position shown, ready for the next pressurization. In a second embodiment, Fig. 5, not shown, in which the action is identical to that above, the control valve 2, with its moving regulator exhaust port 10, is replaced by a simple piston (2) which forms a movable abutment for a single loading spring (14) of the pressure regulator (12). In a known arrangement, Fig. 1, not shown, the quick-release valve 3 has only four lands and the port 15, Fig. 3, feeding the regulator load chamber b, is a restricted port (e), resulting in the slow regulator response above referred to.