GB2328092A - Vehicle braking intensity indicator - Google Patents

Abstract

A pressure sensing device 47 is linked to a motor vehicle's braking system and causes a rearwardly directed visual display unit 1a, 1b to indicate the intensity of braking. A plunger 16 coupled to the brake pedal 12, or another part of the brake operating linkage, moves a contact 15 into engagement with different ones of fixed contacts 14 as braking pressure increases. The contacts 14 are connected to a control unit 10 comprising diodes 9 which cause increasing numbers of lamps 7 to be energised as braking intensity increases. A different form of pressure sensor has an elongate movable contact (21, Fig.8) which contacts increasing numbers of the fixed contacts 14 with increasing brake pressure, so that the diode array 9 is not then required. Braking intensity may alternatively be indicated by varying the intensity of brake lights 7 by means of a variable resistor (25, Figs.12-14) linked to the brake pedal. A further form of sensor may be a brake fluid pressure sensor (33, Fig.18,19). A sensor of the variable resistor or fluid pressure sensing type may be connected to a bargraph driver IC (39, Fig.19) to cause increasing numbers of brake lamps to be energised with increasing braking intensity. The driver IC may also operate an LED display unit (41) mounted on the dashboard.

Description

BRAKING INTENSITY INDICATOR The invention relates to a variable braking intensity visual display or indicator1 Rear brake lights are fitted as standard to motor vehicles throughout the world. Brake lights as they are now are either on or off, they are activated when the driver is braking and are off when the brake pedal is not in use.

Rear brake lights, however, cannot show the intensity of braking or any nuance in a driver's braking behaviour, thus it is impossible to tell from the present lights alone if a driver is "trimming" the speed of a motor vehicle, or if an emergency stop is being performed.

According to the present invention there is provided a rear braking intensity indicator comprising of a rear display unit made of segmented lightable sections arranged sequentially; a mechanical, electrical or electronic means of ensuring the cumulative and sequential illumination of the display lights; and a sensing device for gauging the intensity of braking.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 shows in perspective a single rear indicator unit.

Figure 2 illustrates the internal arrangement of lamps, reflective surfaces and red lens.

Figure 3 shows a typical wiring diagram for the unit.

Figure 4 shows the lamp control circuitry.

Figure 5 illustrates the braking pressure sensing device2 47.

Figure 6 shows the pressure switch circuit diagram.

Figure 7 shows an overall schematic representation of the whole system.

Referring to the drawing, the system comprises of two of the rear indicator units 1 wired in parallel made from a housing unit 4 and a red lens 2. The internal segmentary divisions are indicated 3. Inside the unit the lamps 6 are held in place by internal reflective surfaces 5 and horizontal divider mountings 6. The lamps are wired in parallel, on the one side they connect to ground 8, on the other the leads are available 9 to connect to the control circuit 10, labelled a - e.

These lines a to e are wired into an array 10 of diodes 11 as in figure 4. These ensure that as each new pair of lamps are lit in sequence all the preceding lamps remain lit.

1 hereafter the word "display" and "indicator" are interchangeable.

2 hereafter referred to as the pressure switch.

The parallel arrangement of diodes between each wire ensures minimal voltage loss.

Alternative arrangements will be described later.

The pressure switch is fixed to the brake pedal 12 and the floor of the car 13. The switch 47 comprises of an inner plunger 16 and an outer tube 17, mountings 18 and 19 and contacts 1 4a - e and 15. The pressure switch can swivel about the basal mounting 18 and is fixed at the top to the brake pedal 19. As the brake is depressed further, the plunger is pushed further down into the outer tube. The copper brush (contact) 15 makes contact with the equally spaced copper brushes 14 on the outer tube as the brake pedal is depressed. The outer copper brushes are wired a to e sequentially, e being the contact nearest the brake pedal. The plunger brush is wired to the battery 20.

With particular reference to figure 7 there now follows a brief description of the working of the whole system: Initially, as the brake pedal 12 is depressed only a very small amount, the brush 15 does not touch the first ofthe brushes 14e. As the brake is pushed further, it makes contact with 14e and the first pair of bottom rear lamps are illuminated. Left and right rear indicator units are shown la and lb. As the' pressure on the brake pedal is further increases the brush comes into contact with the next contact 14d. This causes the illumination of the next vertically adjacent pair of lamps and because of the diode between wires dand e, the previous pair of lamps remain illuminated as well. With increasing pressure the process is repeated so that each time a new pair of vertically adjacent lamps are illuminated, the previous lamps remain illuminated. Thus the effect is that increasing pressure on the brake pedal results in an increasingly large surface area of illuminated red area. Finally, with full braking pressure applied the final contact 14a is reached, current flows through all of the diodes in the array 10, and all of the lamps are illuminated. The reverse happens with decreasing braking pressure. Provision is also made for the circuit to be wired into the motor vehicles brake light circuitry 48, if appropriate.

In this particular embodiment, the effect is analogous to an illuminated bar chart or graph in which the single illuminated bar changes size directly in proportion to the degree of braking pressure exerted by the driver.

APPENDICES A description of a variety of arrangements that achieve the same end will now be given.

Figure 8 illustrates the first modified pressure switch.

Figure 9 shows a pressure switch adapted to work from the brake connecting servo rod.

Figure 10 shows the pressure switch miniaturised and directly replacing the standard brake light switch.

Figure 11 illustrates the use of a variable resistance surface replacing the outside copper contacts.

Figure 12 illustrates the arrangement shown in figure 11 as a wiring diagram.

Figure 13 now formally recognises the pressure switch as a variable resistor in this instance.

Figure 14 illustrates a rudimentary circuit diagram for use with a variable resistance pressure switch.

Figure 15 shows the circuit diagram for wiring two diode control circuits in parallel.

Figure 16 illiterates the use of relays in the control circuitry.

Figure 17 illustrates the use of solid state voltage dependant resistance devices such as bi-directional trigger diodes to control illumination of the lamps.

Figure 18 Illustrates the use of a MY 1 00ASP pressure sensor connected to the hydraulic portion ofthe braking system.

Figure 19 shows the use of the MXIOOAP pressure sensor and the solid state Lem3916 Bargraph Display Integrated Circuit in a typical circuit arrangement.

Figure 20 shows an alternative indicator housing Figure 21 illustrates a second possible indicator housing Figure 22 illustrates a range of possible rear mounting sites for the indicators.

Figure 23 illustrates a rear boot mounted version of the indicator.

A modified pressure switch illustrated by filre 8 may be used to obviate the need for an array of diodes or other lamp control circuitry. The brush 21 is now elongated to ensure the cumulative and sequential illumination of the lamps. In this instance as the elongated brush comes into contact with the first contact 1 6e and then the remainder of the brush series, it remains in contact with all the previous brushes, keeping all previously illuminated lamps alight. Thus the cumulative and sequential illumination of lamps is ensured mechanically.

A pressure switch 47 may be attached to any of the moving components of the braking system. Commonly the brake pedal arm 23 will act on a servo connecting rod 22 which can be utilised in the operation of the sensing device. Figure 9 shows the switch attached to the broke connecting servo rod. In this case, the inner plunger 16 is secured directly to the servo rod with the outer cylinder 17 secured to the body of the car 13 as before. As a miniaturised version as illustrated in figure 10 the pressure switch 47 is used to directly replace the standard brake light switch and is attached directly to the bracket 24 provided for the standard version.

Sequential contacts may replaced by a carbon, wire-wound or other, resistance surface 25. This is illustrated in figure 11. For convenience this arrangement is shown on the floor mounted version figure 12 but may be used on any of the aforementioned pressure switches. In this case the pressure switch has effectively become a variable resistor as shown in figure 13. The crudest arrangement for this type of switch is shown in figure 14. Left and right rear indicator units are shown la and lb. Attention is specifically drawn to the fact that the rear indicators are no longer segmented.

Breaking intensity is now indicated by the intensity of the illumination of the rear lamps 7 in response to the amount of resistance surface through which the current in the circuit figure 14 must flow. It is also possible, however, to combine any variable resistance arrangement with a cumulative and sequential illumination of segmented rear units by combing the variable resistance pressure switch with the solid state LM3916 Bargraph Display Integrated Circuit and that will be described later.

Under certain circumstances the cumulative sequential illumination of lamps results in a decrease of the potential difference across the lamps causing a reduced brightness with each sequential illumination. In addition to the obviation of this effect brought about by the elongated inner brush 21 as described in figure 8 (there being no need of any array of silicone devices and therefore no resistance induced decrease in potential difference across the lamps) three further methods are now described. Figure 15 illustrates the principle of the addition of duplicate diode arrays 10 into the circuit in parallel as a means of decreasing the net resistance between each wire a - e. This is the result of the resistance being equal to the reciprocal of the sum of the reciprocals of each resistive component. While this process of adding diode arrays 10 in parallel may be continued ad infirntum two other methods are also indicated. Figure 16 illustrates the use of relays 16 triggered by a series of single diodes 9. In this instance voltage decrease across the diode series is bypassed through relays which switch the lamps on and off. Being of negligible resistance there is negligible decrease in lamp brightness as a result. The relay devices are directly replaceable with voltage dependant resistance devices such as the Bi-directional Trigger Diode (Diac) type STD 27 as illustrated in figure 17.

As the braking system includes a hydraulic component for the transmission of braking pressure it is also it is possible to detect braking intensity information from this source as well. Figure 18 illustrates this principle with respect to a brake calliper 34 but may as easily be implanted or connected into the main brake cylinder or any other part of the hydraulic component of the braking system.. In this illustration brake fluid from the brake cylinder 28 travelling along brake pipe 29 pushes the piston 32 which pushes brake pads 31 onto the disk 30 thus affecting braking. As additional brake fluid enters the reservoir 35 increased pressure acts upon the pressure sensor 33 an example being type MPX100AP. An additional hole 35 specifically to accommodate the pressure sensor 33 has been introduced into the hydraulic component of the braking system.

The unit has seals 36 to ensure that brake fluid cannot leak. The pressure sensor 33 is fixed 37 relative to the calliper 34. In this instance the pressure sensor is shown implanted into the hydraulic system, however, a pressure sensing device could also be attached to the break pad mounting as shown 33b. The pressure sensor 33 produces a variable output voltage in response to changes in pressure in a manner analogous to the aforementioned variable resistance switches. However, it is also possible to replace the pressure sensor 33 with a further miniaturised version ofthe sequential contact pressure switch 47 as described in figure 10.

Any of the aforementioned variable resistance pressure switches or sensors may be combined with the solid state LM3916 Bargraph Display Integrated Circuit 39 or equivalent as shown in figure 19. The LM3916 is specifically designed to provide cumulative and sequential illumination of Light Emitting Diodes 40. Also in figure 19 Light Emitting Diodes (L.E.D.'s) 40 are shown wired in parallel to the out put wires a - e. This arrangement is used to provide an internal dashboard mounted LED, or other indicator system, display 41 that displays braking information simultaneously to the rear indicator units. A 2.2 pF Tantalum or aluminium electrolytic capacitor C1 45 is necessary because of the length of the LED leads. The LED display can be combined with any of the previously described cumulative and sequential illumination arrangements. The LM3916 device is calibrated using resistors R1 43 and R2 44. The mode switch 42 is shown in the bar graph configuration. The input is from the pressure sensor 33 in this case, however any variable resistance device can be connected to the input wires as encircled 46. With the use ofthe LM3916 device 39 the output wires a e are connected to a control circuit as shown in figure 16 or figure 17. In both cases the diode series is surplus to requirements whist the LM3916 is in bar mode but may be retained when the dot mode is enabled. The circuit illustrated by figure 19 is a typical example only.

Claims (7)

1. A rearward facing, interior or exterior mounted motor or other vehicle display or indicator system which is capable of visually displaying the intensity of a driver's braking, comprising of at least one rear mounted unit, a pressure sensing device connected to the motor vehicle's braking system, and appropriate control circuitry.

2. A rearward facing braking intensity indicator as claimed in Claim 1 wherein the rear indicator units increase or decrease in brightness in response to breaking intensity; or:

3. A rearward facing braking intensity indicator as claimed in Claim 1 or Claim 2 wherein the rear indicator units are comprised of at least two discrete sections which are illuminated sequentially and cumulatively in discrete response to braking pressure.

4. A rearward facing braking intensity indicator as claimed in Claim 3 wherein a braking intensity is gauged by a sequential contact pressure switch or a variable resistance device connected to the mechanical or hydraulic component of the motor vehicle's braking system.

5. A rearward facing braking intensity indicator as claimed in Claim 3 or Claim 4 wherein appropriate control circuitry is provided to ensure the changing illumination of single lamp units or the sequential and cumulative illumination of segmented sections in response to breaking intensity information from the sensing unit.

6. A rearward facing braking intensity indicator as claimed in Claim 5 that activates an internal mounted Light Emitting Diode, or other, display wired cooperably to rear lamps in the segmentary units.

7. A rearward facing braking intensity indicator substantially as described herein with reference to figures 1 - 19 of the accompanying drawing.