WO1993011000A1

WO1993011000A1 - Panic stop brake/hazard flasher

Info

Publication number: WO1993011000A1
Application number: PCT/AU1992/000624
Authority: WO
Inventors: Philip Mervin Gins
Original assignee: Bennett, David, Charles
Priority date: 1991-11-28
Filing date: 1992-11-24
Publication date: 1993-06-10

Abstract

A brake light circuit is disclosed for flashing the brake lights (23, 24) of a vehicle in response to emergency braking. The circuit includes an oscillator (25) energised by a motion sensor (20). The oscillator energises relays (RL1/1, RL2/1) for flashing the lights (23, 24).

Description

TITLE "PANIC STOP BRAKE/HAZARD FLASHER" FIELD OF THE INVENTION THIS INVENTION relates to brake light circuit 5 for vehicles. In particular the invention concerns an '* emergency brake light circuit for vehicles.

BACKGROUND OF THE INVENTION

Motor vehicles currently have rear brake lights which are illuminated when the driver of the vehicle

10 depresses the brake pedal. This provides an indication to the drivers of other vehicles that braking action has been initiated. The illumination of the brake lights does not indicate whether the vehicle is simply slowing down, stopping or whether a rapid emergency braking

15 operation is in progress. The brake lights are generally only visible from the rear of the vehicle. Vehicles are provided with hazard lights visible from both the front and the rear of the vehicle but such lights are usually only illuminated manually and then only while the vehicle

20 is stationary.

It is an object of the present invention to provide a brake light circuit for vehicles which at least minimise the disadvantages referred to above.

DISCLOSURE OF THE INVENTION 25 According to one aspect, the invention provides a brake light circuit for a vehicle having brake lights, the circuit including a sensor for detecting deceleration of the vehicle at a rate faster than a predetermined value and/or emergency actuation of the brakes of the 30 vehicle and an oscillator circuit for periodically flashing the brake lights of the vehicle in response to

_* emergency actuation of the brakes and/or deceleration at a rate faster than the predetermined value.

_* The sensor may comprise a motion sensor, one or 35 more wheel speed sensors, an hydraulic brake fluid sensor or pressure sensor. A typical motion sensor may consist of a mercury switch. One or more wheel speed sensors may be used where the vehicle is fitted with an electronic skid prevention circuit or an anti-skid braking system. Preferably one such speed sensor is associated with each wheel of the vehicle. Where an hydraulic brake fluid sensor is employed that sensor maybe responsive to changes in brake fluid pressure to provide an indication of emergency braking. A pressure sensor may also be used simply to detect pressure on the brake pedal.

The oscillator, where the vehicle has anti lockup electronic skid prevention circuits, may be provided by the computer normally forming part of the skid prevention circuits. Alternatively a separate oscillator may be present for flashing the brake lights. The oscillator may be used to control relays or other switching means interposed between it and the brake lights.

In another embodiment, the circuit of the invention also flashes the turn indicators or hazard lights in response to emergency braking. In that instance two oscillators may be used, one for controlling the brake lights, the other for controlling the indicator lights or hazard lights.

The frequency of oscillation may be any desired rate but should be sufficiently fast so as to attract attention but not too fast. It has been found that a rate of 2 or 3 cycles per second is adequate although the rate may be faster than this if desired.

DISCLOSURE OF THE DRAWINGS Particular preferred embodiments of the invention will now be described by way of example with reference to the drawings in which:

Figure 1 is a block diagram of a circuit according to an embodiment of the invention; and

Figure 2 is a detailed circuit diagram of a circuit according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS With reference to Figure 1, the wheels 10, 11, 12 and 13 are shown diagrammatically. Wheels 10, 11 are the front wheels while wheels 12, 13 are the rear wheels. Each wheel has a sensor 14 associated with it. These sensors, where the vehicle has anti lockup electronic skid prevention circuits and a computer for controlling the circuits may, comprise electronic speed detectors. An indication of decelerating can readily be obtained by differentiating the speed signal. If the rate of change of that signal exceeds a predetermined value indicative of heavy braking and the brake pedal microswitch 15 is operated, the computer 16 may then flash the brake lights to indicate heavy braking which would occur in an emergency braking situation. The computer can also be used to flash the hazard lights in such a situation. As operation of the brake lights so that they flash in an emergency braking situation is dependant upon the deceleration exceeding a predetermined value, the brake lights of the vehicle continue to function in the normal manner once heavy braking has ceased or during normal braking.

Figure 2 provides details of a circuit which may be used where the vehicle does not have computer controlled anti lockup electronic skid prevention circuits or where it is desired not to use those circuits with the circuit of the invention.

The circuit includes a motion sensor 20 which in this embodiment is a mercury switch. An alternative sensor may comprise a sensor for detecting braking force or effort. For example a pressure sensitive may be incorporated in the hydraulic braking circuit which would operate when the hydraulic pressure exceeds a predetermined value.

The circuit shows the left and right hazard lights 21, 22 as well as the left and right brake lights 23, 24. The brake lights are powered in the usual way. The circuit includes a twin timer 25 which in this embodiment is an LM556N timer configured as two astable oscillators. Capacitor and resistor Cl, Rl provide the time constant for one of the oscillators while capacitor and resistor C2, R2 provide the time constant for the other oscillator. One oscillator output is available at pin 9 and the other at pin 5.

Relay RL4/1 is connected between a reference potential (earth in this embodiment) and sensor 20. Sensor 20 is connected to a source of power as shown. When sensor 20 detects deceleration of the desired magnitude (indicative of emergency braking) the relay RL4/1 is energised and contact RL4 is closed. This provides power for timer 25.

An oscillating output at pin 9 of timer 25 causes relay RL3/1 to operate to alternately close and open contact RL3 at a desired rate typically about 2 to 3 cycles. This in turn operates and flashes the left and right hazard lights 21, 22 of the vehicle. Diode Dl is a protection diode for relay RL3/1 and diodes D2, D3 isolate the lights 21, 22 for normal hazard or turn indication operation. Series connected resistor R3 and capacitor C3 provide a spark quenching circuit.

An oscillating output at pin 5 is made available to relays RLl/1 and RL2/1. Both of these relays have protection diodes D4, D5. Relay RLl/1 is energised when pin 5 is high and RL2/1 operates when pin 5 is low. This causes an alternating action between RLl/1 and RL2/1. These relays control contacts RL1 and RL2 respectively and flash the lights 24 and 23.

Rear brake lights 23, 24 and the indicator lights 21, 22 will continue to flash while the brake pedal is depressed following an emergency braking action. When the pedal is released the power supply to the circuit is removed and relay RL4/1 will be de-energised and contact RL4 will open. The circuit will not re- operate until sensor 20 once again detects emergency braking.

The circuit may be conveniently mounted at the rear of the vehicle preferably in the boot of the vehicle and does not detract in any way from the normal function of the braking and indicator lights of the vehicle. The circuit provided additional information depending upon the rate of deceleration.

Claims

CLAIMS:

1. A brake light circuit for a vehicle having brake lights, the circuit including a sensor for detecting deceleration of the vehicle at a rate faster than a predetermined value and/or emergency actuation of the brakes of the vehicle and an oscillator circuit for periodically flashing the brake lights of vehicle in response to emergency actuation of the brakes and/or deceleration at a rate faster than the predetermined value.

2. The circuit of Claim 1 wherein the oscillator periodically flashes hazard or turn indicator lights as well as the brake lights when the sensor detects deceleration of the vehicle at a rate faster than the predetermined value and/or emergency actuation of the brakes of the vehicle.

3.- The circuit of Claim 1 or 2 wherein said sensor comprises one or more wheel speed sensors.

4. The circuit of Claim 1 or 2 wherein the sensors comprises an hydraulic brake fluid sensor.

5. The circuit of Claim 1 or 2 wherein the sensor comprises a motion sensor.

6. The circuit of Claim 5 wherein the motion sensor consists of a mercury switch.

7. The circuit of Claim 2 including two said oscillators, one said oscillator being operative for periodically flashing the brake lights and the other said oscillator being responsive for periodically flashing the turn indicator or hazard lights of the vehicle.

8. The circuit of Claim 7 including a first relay energised in response to the sensor for providing power to the or each said oscillator.

9. The circuit of Claim 8 including a second relay energised by the other said oscillator for flashing the hazard or turn indicator lights.

10. The circuit of Claim 9 including a third and a fourth relay associated with the one said oscillator for flashing a right said brake light and a left said brake light.

11. The circuit of Claim 7 or 8 wherein the or each said oscillator includes timing components for varying the time constant and hence the oscillation rate of the or each said oscillator.