Patent GB-1153831-A (GB)
Title: Hydraulic Braking Systems
Inventor: MIZUNO AKIRA
IPC: B60T11/10
Filed: 1967-02-07
Abstract: 1,153,831. Hydraulic brakes. GOSHI KAISHA MIZUNO KOGEISHA. 7 Feb., 1967 [17 Nov., 1966], No. 5857/67. Heading F2F. [Also in Division H1] In an hydraulic braking system for vehicles, a non-return solenoid valve 3 is disposed between the master cylinder 2 and the wheel cylinders 6, 8 of the brake system, motion detecting means 10, 11 adapted to operate during travelling of a vehicle is in the form of an alternating current signal generator 10 consisting of a rotary magnet 10 and a reed switch 12, a control circuit being provided across the motion detecting means and the non-return solenoid valve 3 for passing a signal generated by the motion detecting means to the solenoid valve 3 to place the valve in a position in which it allows brake fluid to flow therethrough in both directions during motion of the vehicle and an accelerator operated switch 17 is operatively connected to the non-return solenoid valve 3 to bring the valve into a non-return position during starting of the vehicle. When the vehicle is at rest and the brake pedal 1 is applied, fluid is prevented from returning to the master cylinder by the action of the solenoid valve 3 and will remain in effect until the accelerator is pressed and the vehicle moves forward. Fig. 2 shows the electrical circuit to control the hydraulic circuit and a permanent magnet 10 having four poles is mounted on a rotary shaft 11 operatively associated with a flexible shaft which drives the speedometer of the vehicle so that it is rotated at a rate proportional to the speed of the vehicle. Arranged adjacent to the rotatable permanent magnet 10 is a reed switch 12 which is opened and closed repeatedly as the permanent magnet 10 rotates to form an alternating current generator. A battery 13 supplies current through an ignition switch 14 and a contact 4<SP>1</SP> of an hydraulic pressure switch 4 which is connected to an accelerator operated switch 17. One terminal of the accelerator switch 17 is connected to a terminal 19 of a solenoid 3<SP>1</SP> of the non-return solenoid valve 3. When the brake pedal 1 is actuated during movement of the vehicle, brake fluid is supplied to the wheel brake cylinders and at the same time the contact 4<SP>1</SP> of an hydraulic switch 4 is closed to supply power to the transistor circuit causing the reed switch 12 to be opened and closed by the rotating permanent magnet 10, the transistor 32 being brought into conductive state to permit the solenoid 3<SP>1</SP> to be energized. The non-return solenoid valve 3 is then brought into an open position to permit the brake fluid to flow back into the master cylinder when pressure is removed from the accelerator pedal during motion of the vehicle. The control circuit is composed of a capacitor 22, diodes 23 and 24, resistances 25 and 26, capacitor 27, resistances 28, 29 and 30, transistors 31 and 32 and a capacitor 33. Instead of providing an accelerator switch which is operatively connected to the accelerator mechanism, a microswitch may be actuated by the movement of a pressure sensing diaphragm provided in association with the suction manifold of the engine and adapted to sense negative pressure developed in the suction manifold, the microswitch being closed upon actuation of the accelerator by an increasing suction negative pressure developed in the engine. When a force is exerted on the brake pedal during movement of the vehicle and is continuously applied to the brake pedal until the vehicle is brought to a halt, the opening and closing action of the reed switch 12 stops coincidently with the stoppage of the vehicle and, as a result, the transistor 32 becomes non-conductive and the solenoid 3 1  is thus released from excitation to place the valve 3 in a non-return position to keep the hydraulic pressure in the wheel brake cylinders at the elevated level to retain the wheels in a braked condition. When a force is applied to the accelerator pedal the accelerator switch 17 is closed and the current is allowed to flow from the battery 3 to the solenoid 3<SP>1</SP> through switch 14, contact 4<SP>1</SP> and switch 17 to bring the non- return solenoid valve 3 into an open position to provide for the flow of brake fluid in both directions so that the wheels are released from the brake condition automatically.