Patent GB-521352-A (GB)
Title: Improvements in or relating to controlling means for automotive vehicles
Filed: 1938-11-15
Abstract: 521,352. Controlling brakes and engine or like power on motor vehicles. MIEKLEJOHN, E. L. Nov. 15, 1938, No. 33156. [Class 79 (v)] [Also in Group XXXIV] A control system, in which a single member such as a pedal controls the brakes and the engine throttle or an equivalent member, comprises hydraulic mechanism which responds to movement of the single control member so as either to control the engine power or apply the brakes depending upon -the rate at which the control member is moved. Thus, if the control pedal is depressed comparatively slowly the throttle is opened until it reaches its maximum opening ; further depression of the pedal allows the throttle to close and applies the brakes. If the pedal, at any position, is rapidly depressed pressure is built up in the hydraulic mechanism and the brakes are applied, the throttle being allowed to close if it has been opened. In the construction shown in Figs. 1 and 2 a pedal 3 actuates a plunger 2 in a cylinder 1 connected by a pipe 29 to the brake cylinders (not shown) and by a pipe 9 to a valve A controlling the throttle lever 5. The valve controls conduits 9a, 10 leading respectively to a throttle-operating plunger 4 and a reservoir 6, and comprises two heads 7, 8 connected by a hollow .stem 8a having ports 8b therein. Normally the valve is held by a spring 11 in the position shown in Fig. 2, in which the pipes 9, 9a are connected. When the pedal 3 is depressed slowly the slight pressure rise in the system has no effect on the brakes, and the liquid passes by the valve head 7, which has a small clearance in its chamber, to operate plunger 4 and open the throttle against the resistance of the usual light spring 12. If the pedal movement is continued beyond 'that corresponding to maximum throttle opening the pressure rises and the valve heads 7, 8 are moved to cut off the plunger 4 from the pressure cylinder 1 and connect it to the reservoir 6, so that the throttle is closed by its spring 12 ; as the pressure rises the brakes are applied through the pipe 29. If the pedal 3 is depressed rapidly from the starting position the pressure builds up behind the valve head 7 and closes the latter so that the throttle plunger is cut off from the cylinder 1 and is not actuated ; the brakes are then applied. In order to obtain an approximately uniform resistance to throttle opening a balancing or dead-centre spring 25 acts on the throttle lever 5 in conjunction with the spring 12. In a modification, a single spring acting at an angle on the lever 5 is employed for this purpose. A spring stop 13, Fig. 2, may be employed to cause the valve 7, 8 to close only at a predetermined pressure; the spring of this stop may be adjusted by a driver's control 15 acting on a screw 14. The movement of the valve 7, 8 may be assisted by a solenoid 16 energised through contacts 17, closed by depression of the pedal 3, and contacts 18 closed by a member 19 when the valve has started to move In order to economise electricity a resistance 20 is inserted in the circuit when the valve has been operated, a rod 21 on the valve opening contacts 22. The solenoid may be independ ently energised at any time by a hand-operated switch 23, the pedal 3 then controlling the brakes only. In order to facilitate the closing movement of the throttle a bye-pass 26 provided with a one-way valve 27 may connect the throttle plunger cylinder and the master cylinder' 1. In the construction shown in Fig. 9 the pedal lever 3 carries a foot-plate 3a hinged thereto, the heel end of this plate bearing on a roller on a lever 35 pivoted at 35a and acting at its lower end on a double valve 7, 8. The lever 35 is normally urged by a spring 37 to the position shown. When the toe-end of the plate 3a is depressed the lever 3 is rocked and operates the plunger 2 so that liquid passes along pipe 9 past the open valve 7 through pipe 9a to the throttle-operating cylinder to open the throttle. On continued movement of the pedal beyond the position corresponding to maximum throttleopening, the consequent rise of pressure in the system operates a plunger 36 which rocks the lever 35 clockwise to close valve 7 and open valve 8, thus allowing the throttle to close ; the brakes are applied through the pipe 29, as before. Rapid movement of the pedal at any time also causes actuation of the plunger 36 to close the throttle, the pipe 9a having a small bore. When the heel end of the foot-pedal 3a is depressed the lever 35 is directly rocked to close valve 7 and open valve 8, thereby isolating the throttle plunger from the pressure cylinder 1. In a modification, the hydraulic brakes may be operated by a master cylinder co-axial with the pressure cylinder 1, the plunger 2 acting hydraulically on the plunger of the master cylinder but having an extension which acts mechanically in the case of failure of the pressure in the cylinder 1. In the construction shown in Fig. 4 the pedal arm 3 carries a lever 30 the ends of which are respectively connected by links 31, 32 to the plunger 2 controlling the throttle and to means operating hydraulic or mechanical brakes. When the pedal is depressed the resistance of the brake springs or the like causes the lever 30 to rock about the end of link 32 so as to operate plunger 2 and open the throttle. If, however, the pressure in cylinder 1 builds up sufficiently to close the valve 7 (not shown) further movement of the plunger 2 is prevented and the lever 30 then rocks about the end of link 31 to apply the brakes. In order to ensure that if one system breaks down the other will still operate limiting stops 33 are provided 'against which the lever 30 can abut. The valves 7, 8 may be arranged co-axially with the cylinder 1 and so as to be operated mechanically by the plunger 2 in case of a leak in the throttle system. A separate hand throttle control may be provided comprising a twist grip on the steering wheel connected by a cable through a strong spring to an extension of the lever 30, which in this case has a pin-and-slot connection with the pedal 3. With this arrangement the throttle can be set at any desired predetermined opening, but when the brakes are applied the throttle is closed and the twist grip which has only a frictional setting, is also returned to its closed position. To assist this closing movement a solenoid acting on the twist grip may be wired in parallel with the solenoid operating the valve 7, 8.