AU653741B2 - Control of brakes on vehicles - Google Patents

Description

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AUSTRALJIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT 00000.

0 0 0000 00 00 0 00 0 0 @0 Name of Applicant: Actual Inventor: Address for Service: BRUCE EDWARD FURSEY Bruce Edward Fursey PETER AWEL& ACSSO-I-ATL-S- Patent Trd ark At-rn-ey-s 255 Adela-de--St-reet 3S DRSIBA- QD4~O- S&eG (GP-O-Box ,,31-25-BR-SEBANF-4001) Invention Title: "Control Vehicles" of Brakes on Details of Associated Provisional Application No: Australian Patent Application No. PK2037 filed 30 August, 1990.

SAl The following statement is a full description of this invention., including the best method of peAr~7i -Y -w to me: THIS INVENTION relates to control of brakes on vehicles and in particular but not limited to control of brakes on trailers from within a towing vehicle.

It is customary to operate the brakes of a trailer in unison with the brakes of the vehicle towing the trailer (the towing vehicle). Thus, a trailer brake controller can be installed on the towing vehicle or on the trailer, the controller being activated by operation of the brakes of the towing vehicle.

In one known controller, a variable braking power setting can be employed. The maximum braking power can be preset depending on the nature of the load being towed.

0000 Where there is a small load, the braking required is less than for a heavier load and so forth. In one controller a finger operated switch is wired in parallel with the brake of light switch on the towing vehicle so that the brakes on the trailer can be operated independently of the brakes of the towing vehicle. Thus, the driver of the towing vehicle has two options, he can push his foot on to the brake pedal, thereby activating the brakes of both vehicles or he can o elect to operate the finger switch so the brakes of the trailer operate to the preset value while the brakes of the towing vehicle do not operate.

e• e• S° While the driver is presented with the two options, the finger operated switch is in fact superfluous as minimal foot pressure on the brake pedal will switch on the brake lights of the towing vehicle without activating the brakes of the towing vehicle. As the switching current for the controller

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-3is wired to the brake light switch, current will be delivered to the controller and the brakes of the trailer will operate. Thus, by placing enough pressure on the brake pedal, the brakes of the trailer can be operated without operating the finger switch or the brakes of the towing vehicle.

It is an object of the present invention to provide an alternative controller for the brakes of a trailer which offers advantages when compared to the aforementioned prior art.

In one aspect, the invention resides in a controller for the brakes of a trailer, the controller being of the type operated by a driver placing his foot on the brake Soo: pedal of the towing vehicle, characterised in that a e" 15 manual override switch is employed to alter the path of current through the controller such that the braking level on the brakes of the trailer can be changed independently of the operation of the brake pedal, by operation of the manual override switch, to a different level than when the brake pedal is operated.

Where the power level to the brakes of the trailer variable and can be preset, it is preferable that a potentiometer be used for this purpose. The *o potentiometer is preferably wired in series with the 25 brake light switch to enable the normal operating current of the controller to be preset for different braking levels. It is therefore preferable that a diode or other device be employed downstream of the potentiometer in order to prevent excessive back current that may damage the potentiometer when the manual override switch is activated.

As mentioned above, controllers are typically mounted S:20248A on the towing vehicle or on the trailer. It will be appreciated that where a controller is trailer mounted, the override switch is not required. It is therefore preferable that the controller be made using a circuit board which is compact and has the capability of having the manual override switch to be omitted for the purpose of trailer mounting.

Thus, it is preferred that the invention be embodied in a printed circuit board which is dual purpose. Advantageously, therefore in another aspect of the invention, there is provided a printed circuit board employed within a compact 0e e housing so that a main power transistor can be mounted at one ost.

end of the board, the board having capacity for the manual override switch and potentiometer connections so that the *0 OS *o o SS controller fits within the a package about 4cm to 6cm wide by 6cm to 8cm long and icm to 2cm deep. Taking into account the current loadings for the printed circuit board, it is possible, using the teachings of the present invention, to 0 S install the relevant controller connections on a printed eS S circuit board having side dimensions ranging from about 4cm 20 to In order that the invention can be more readily @000 ".o0 understood and be put into practical effect, reference will now be made to the accompanying drawings and wherein:- Figure 1 is a schematic circuit diagram illustrating the installation of a controller according to the present invention; Figure 2 is a circuit diagram illustrating one preferred embodiment of a controller according to the present invention; Figure 3 is a circuit diagram illustrating another preferred embodiment of a controller according to the present invention; and Figure 4 is a diagram illustrating a printed circuit board suitable for implementation of the circuits of Figures 2 or 3, the printed circuit board also being adaptable for a trailer mounted controller.

Referring to the drawings and initially to Figure 1, there is illustrated a controller 10 according to the present invention which can be mounted on a towing vehicle (not e g.

shown), the controller 10 being of the type operated by a S.. 0e 000 driver placing his foot on a brake pedal of the towing 0* OS 0009 SS vehicle in order to switch the brake light switch 11, the

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switch 11 supplies current to the existing brake lights of the towing vehicle along line 12 and to the trailer and also current to the controller 10 along line 13. When current is eee•• delivered to the controller 10 along line 13, current is in turn delivered to the brakes of the trailer via line 14. A 20 manual override switch illustrated at 15 is an intermittent switch which carl be operated by finger touch in order to o o divert current directly from the battery line 16 to the brake line 14 independent of the position of switch 11. Thus, by operating switch 15 a greater control current can be delivered and proportionally amplified to effect a change in braking power at the trailer.

Figures 2 and 3 illustrate detailed circuit diagrams of typical controllers 10 and referring to Figure 2, there is illustrated a circuit diagram of a controller 17 suitable for implementation in the arrangement of Figure i. Where appropriate, like numerals have been used to illustrate like features. In this embodiment, the manual override switch is a double pole, double throw switch 18 which is wired in parallel with a potentiometer 19. The potentiometer 19 allows manual presetting of the current drawn from the brake light switch along line 13. On activation of the brake light switch 11, when the driver of the towing vehicle places his foot on the brake pedal, a preset current will be delivered along line 13 through the potentiometer 19 to the base of *000 transistor 20 thereby switching transistor 20 on at a 0 predetermined current level determined by the current level flowing through potentiometer 19. This will in turn, determine the ultimate current level switched through power transistor 21 and thereby delivered to the output line 14 and thereby to the brakes of the trailer. Thus, the braking 0 0 power of the brakes on the trailer can be manually preset go I using potentiometer 19.

Activation of switch 18 will accomplish two results, firstly, current will be delivered to the brake lights of the e towing vehicle along lines 22 and 13 and secondly, full S. currenz will be delivered along line 23 to switch transistor on to its maximum level for the circuit shown, this in turn will cause transistor 21 to deliver maximum current for the circuit shown to the line 14 for maximum braking power at the trailer.

As a precaution and bearing in mind the possibility of low resistance levels being preset on potentiometer 19, a diode 24 is employed downstream of the potentiometer 19 to prevent reverse current flow which may cause damage to the potentiometer 19.

Figure 3 illustrates an embodiment of the invention similar to the Figure 2 embodiment and where appropriate, like numerals have been used to illustrate like features.

The controller in this case is numbered generally at 25 and in this embodiment, the double pole, double throw switch 18 of Figure 2 has been replaced by a single pole, single throw switch 26 and diode 27 combination. This arrangement has 0000 space saving features which enable the circuit of Figure 3 to

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be placed into a more compact package than the embodiment of 0 eon Figure 2 as the switch 18 takes up more space than the switch

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26. As for the embodiment of Figure 2, under normal operation of the Figure 3 embodiment, a preset current flow through potentiometer 19 enables a predetermined output along oi°i ro. line 14. On activation of the switch 26, current will be delivered through diode 27 along lines 22 and 13 to light the brake lights of the towing vehicle. At the same time, current will by-pass potentiometer 19 by travelling along oo line 23 to enable delivery of maximum current to the trailer brakes along line 14.

Clearly for operation inside the towing vehicle, the switches 18 and 26 in either case must be in close proximity to the driver so that he can easily activate the switch. In the case of a trailer mounted controller, the switches 18 and 26 and the diode 24 can be omitted. In the case of the Figure 3 embodiment, the diocde 27 will also be omitted, a conductive link will be installed in place of the diode 24 in each case. Thus, on the trailer mounted controller, the option for delivery of maximum current to the brakes of the trailer will be unavailable.

Referring to Figure 4, there is illustrated an enlarged scale diagram 31 of a printed circuit board suitable for implementation of the circuits of Figures 2 and 3 as well as being suitable for use in a trailer mounted controller. The overall dimensions of the printed circuit board illustrated in Figure 4 is about 4.5cm by 4.5cm and appropriate scaJing @000 applies. The earth connection of circuits 17 and 25 is made S to the board along conductor path 32 and for convenience, the 0 0 various circuit components depicted in Figures 2 and 3 are e.

drawn on Figure 4 but it will be understood that these are normally omitted in the normal printed circuit board prior to assembly of the circuit. Like numerals have been used to illustrate like features. The connections of transistor 21 to the printed circuit board are given at 33 which represents 20 the base connection, at 34 which represents the collector connection and at 35 which represents the emitter connection.

0 The connections of transistor 20 are given at 36 being the 0* OS base connection, 37 being the collector connection and 38 being the emitter connection. The switches 18 or 26 have their connections, in which either case applies at 39 and to the conductors 40 and 41 as the case applies, the conductor 41 is connected to line 16 and the conductor 40 being connected to line 13, the conductor 42 being connected to the output line 14. As can be seen, the compact size of the printed circuit board comes as a result of the design of the board which has a basic U-shape configuration defined by the conductor 42 and the connections to transistors 20 and 21 which surround the conductors 40 and 41.

From the foregoing, it will be appreciated that by employing the present invention, the driver of a towing vehicle has the option of delivering different braking power to the brakes of a trailer depending on whether he operates the brake pedal or the manual override switch. The manual override switch can deliver maximum braking power as in the 0el illustrated embodiment or by use of suitable resistors, the change in braking power delivered by this route can be altered if desired. Thus, in cases where maximum braking power is required for say, emergency reasons, this can be delivered to the trailer simply by activating the override switch. Under normal operation, the trailer brakes can be operated in unison with the brakes of the towing vehicle or eo by the driver lightly placing his foot on the brake pedal, he can selectively operate the brakes of the trailer to the preset level as set by potentiometer 19. Thus, according to 0666 the present invention, the driver has in fact three options S* for brake control.

Whilst the above has been given by way of illustrative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set forth in the appended claims.

Claims (4)

1. A controller for the brakes of a trailer, the controller being of the type operated by a driver placing his foot on the brake pedal of the towing vehicle, characterised in that a manual override switch is employed to alter the path of current through the controller such that the braking level on the brakes of the trailer can be changed independently of the operation of the brake pedal, by operation of the manual override switch, to a different level than when the brake pedal is operated.

2. A controller according to claim 1 including a potentiometer to enable the current passing through the controller to be preset for different braking levels.

3. A controller according to claim 2 wherein a diode or other device is employed downstream of the potentiometer :o in order to prevent excessive back current that may damage the potentiometer when the manual override switch is activated.

4. A controller substantially as described with reference to the accompanying drawings. o DATED this 4th day of August 1994 BRUCE EDWARD FURSEY By his Patent Attorneys GRIFFITH HACK CO. S:20248A ABSTRACT A controller (10) can be mounted on a towing vehicle and is of the type operated by a driver placing his foot on a brake pedal of the towing vehicle in order to switch the brake light switch the switch (11) supplies current to the existing brake lights of the towing vehicle along line (12) and to the trailer and also current to the controller along line When current is delivered to the controller (10) along line current is in turn So delivered to the brakes of the trailer via line A manual override switch illustrated at (15) is an intermittent switch which can be operated by finger touch in order to ,6 divert current directly from the battery line (16) to the 4. brake line (14) independent of the position of switch (11). Thus, by operating the switch a greater control current can be delivered and proportionally amplified to effect a change in braking power to the trailer and is particularly oo s suitable in case of emergency. V i eq U 0