GB2352011A - Adjusting a newly assembled brake system in a motor vehicle - Google Patents

Abstract

In a newly assembled brake system comprising a master cylinder 2 coupled to brake cylinders 3 through a pipe network 4, any slack in the system is eliminated upon application of a single pulse or a sequence of pressure pulses from a pressurisation mechanism 5 under the control of a controller 6 through the master cylinder 2 and the pipe network 4 to the brake cylinders 3, and the brake cylinders are retained in their adjusted configuration. Thus, a handbrake can be adjusted following adjustment of the brake cylinders 3, and it is unnecessary for an operative to provide a one-off or repeated pumping of the brake pedal to effect initial brake adjustment. The pressurisation means can supply compressed air or other gas, or hydraulic fluid, and, for adjustment, hydraulic fluid and/or compressed air may be contained in the brake system.

Description

2352011 An Apvaratus and Method of Brake Setting within a Motor Vehicle

The present invention relates to an apparatus and a method of brake setting within a motor vehicle and in particular the hand or parking brake of such a vehicle.

Clearly, upon initial manufacture of a motor vehicle it is necessary to adjust various control mechanisms in order to take up slack and provide operational function. Thus, with regard to the brake system of a vehicle it is necessary to set the system in order that both the service and hand brakes are operational. It will be understood that initially the brake callipers or drums must be adjusted to be operational upon displacement of a foot pedal.

The present invention relates in particular to adjusting the hand brake settings of a brake system within a vehicle. Traditionally, upon production of a new motor vehicle an operative will be asked to either provide a one-off or repeated operation of the brake pedal in order that the brake system and in particular calliper or brake drum shoe stand-off is adjusted in order that the brake system is operational. Thus, with regard to the present invention where handbrake adjustment is required it will be understood that such adjustment of the brake calliper or drum brake is necessary before the handbrake cable and lever is set. If the handbrake is set before calliper or brake drum adjustment is performed, then clearly, when the calliper or brake drum adjusts the result can be over- adj ustment with perhaps potentially binding of the vehicle brakes.

Typically, the handbrake is coupled to the brakes through a cable such that this cable upon deployment about a lever pivot can be tensioned in order to bring the brake system into operation.

As intimated previously, there are in principle two techniques with regard to adjusting the brake system. In a first technique of a "one- shot" type, the service (foot) brake pedal is displaced once normally by an operative's hand such that calliper or drum brake off-set is eliminated. Alternatively, in a second adjustment manner, there is an incremental adjustment of the brake system such that the service (foot) brake pedal is repeatedly operated until calliper or drum brake offset is eliminated. With the respective brake components thus, in close association, it will be understood that further operation of the service (foot) brake pedal provides braking force as required.

As the operation of the service (foot) brake pedal is conducted by an operative, typically by hand, and potentially repeatedly in order that there is a ratchet takeup, it will be understood that these prior arrangements and methods of brake system adjustment are tiring, unreliable and potentially erroneous. Furthermore, it will be understood that in order to provide the necessary adjustment of the brake system prior to handbrake setting, that it is necessary to fill the brake system with an hydraulic fluid which may be inconvenient for that particular stage of motor vehicle manufacture.

It is an object of the present invention to provide an arrangement and method of brake system adjustment which substantially relieves the above mentioned problems.

In accordance with the present invention there is provided a brake adjustment arrangement for a motor vehicle, the arrangement including a master cylinder and a plurality of slave cylinders coupled together through a pipe network, the slave cylinders include a displacement means to provide, in use, a brake function when forced into engagement with a brake actuator by a brake force applied through the pipe network from a brake force applicator whilst said 3- master cylinder is coupled to pressurisation means in order to initially pressurise the pipe work and slave cylinders whereby each displacement means is initially displaced to be adjacent to its brake actuator to allow adjustment of the brake force applicator for direct application of the brake force without off-set 5 therebetween.

Typically, the pressurisation means will be arranged to provide single or multiple pressure pulses for initial pressurisation to the pipe work and slave cylinders.

The pressurisation means may use compressed air or hydraulic fluid or a combinatlion thereof to provide pressurisation to the network and master and slave cylinders.

Alternatively, the present invention comprises a method of brake actuation adjustment in a master/slave cylinder brake arrangement including; a. coupling a pressurisation device to the master cylinder of the brake arrangement; b. initially applying pressurisation fluid to the arrangement such that any off-set between the displaceable means and the brake actuator for each slave cylinder is eliminated so that these displaceable means and the actuator are adjacent; and, c. adjusting the arrangement to retain that adjacent configuration between the displaceable means and the brake actuator.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawing in which a schematic illustration of a brake arrangement is depicted.

Most brake arrangements used within a motor vehicle comprise a master cylinder and respective slave cylinders for each wheel of the vehicle. The master cylinder and slave cylinders being coupled together through a pipe network such that a hydraulic pressure can activate the brakes through appropriate actuator means. Thus, essentially each slave cylinder incorporates a displaceable piston which acts against an actuator in order to provide a braking function. The master cylinder acts as a central distributor for hydraulic fluid and is appropriately activated by a brake force applicator such as a foot pedal within a vehicle.

The present invention essentially relates to handbrake adjustment upon initial manufacture of a motor vehicle.

It will be understood that upon initial manufacture of a motor vehicle the respective displaceable cylinder and brake actuator will typically not be arranged consistently and with an acceptable configuration therebetween. Thus, as indicated previously, it is normal for the brake arrangement to be adjusted to achieve adequate brake function performance.

With regard to the handbrake, it will be understood that the brake cable between that handbrake and the slave cylinder combination of displaceable piston and brake actuator will be trimmed once appropriate configuration is achieved in the slave cylinders. For information, normally only the rear wheels and thus the rear slave cylinders will be actuated by the handbrake through its brake cable.

Clearly, as indicated previously one approach to ensuring appropriate configuration in the slave cylinders is to pump or stroke the brake force applicator such as a foot pedal in order that the system through the pipe network forces the displaceable piston and the actuator into an adjacent close configuration as required for normal brake function. However, as indicated previously such manual actuation of the brake force applicator is time consuming, tiring to a vehicle production operative and also due to the variation in operator stroking prone to providing erroneous results.

In view of the above depicted in the drawing is a brake arrangement 1 in which initialisation or set-up adjustment can be made without operative stroking of the brake arrangement 1 force applicator. This brake arrangement 1 comprises a master cylinder 2 which is coupled to slave cylinders 3 through a pipe network 4. Thus, a hydraulic fluid located in the pipe network 4 and master cylinder 2 along with slave cylinders 3 can be pressurised in order to provide respective brake function in each brake cylinder 3 with regard to an associated wheel of a vehicle.

In accordance with the present invention associated with the master cylinder 2 is a pressurising mechanism 5 controlled by a controller 6. This pressurising - mechanism 5 provides a pressure to the master cylinder 2 such that a fluidic pressure is presented to each slave cylinder 3 in order to bring that slave cylinder 3 into the appropriate configuration for brake function actuation.

It will be understood that the present brake adjustment arrangement will typically be utilised at the point of vehicle manufacture. Thus, at an appropriate point in motor vehicle assembly the pressurising mechanism 5 will be secured to the master cylinder of the brake arrangement such that appropriate fluidic pressure is presented within the brake arrangement.

- 6 " Those skilled in the art will appreciate there are a variety of manners by which this fluidic pressure can be presented within the brake arrangement and in particular the master cyhnder 2 along with pipe network 4 and slave cylinders 3. However, the present invention inherently due to the consistency of the pressurising mechanism 5 ensures there is only limited variability in the arrangement 1 such that there is a consistent adjustment and therefore setting of the brake arrangement 1 for better performance. Essentially, the slave cyhnders 3 are pressurised through the master cylinder 2 in order to bring each slave cylinder 3 into appropriate conformity for normal brake operation. Once in such appropriate configuration the handbrake lever/cable can be adjusted to provide direct operation when required.

I It will be understood that once the initiahsed fluidic pressurisation of the slave cylinders 3 is removed by the mechanism 5 that the clisplaceable piston and brake actuator will be in close association but without forced engagement such that there win be hmited if any braking function therebetween. However, once a brake force is applied through a brake force appheator then forced engagement will be achieved and a braking function provided with respect to its associated wheel of a vehicle.

With the appropriate configuration within the slave cyhnder 3 as indicated previously a handbrake cable will be adjusted such that once released that cable will not actuate the slave cyhnders 3 associated therewith. However, in order to provide a braking function to hold the vehicle when parked or otherwise, it will be understood that the cable will be retracted or pulled in order to bring the slave cylinders 3, normally only the rear cyhnders 3, into operation.

in a first embodiment of the present brake adjustment arrangement 1 the pressurisation mechanism acts during the so-called evacuation and fill process for the brake arrangement 1. Thus, as hydraulic fluid is forced into the master cylinder 2 under pressure, generally around 3 Bar, each displaceable piston is moved towards the brake actuator within its respective slave cylinder 3 until they are adjacent with regard to each other. Once the fill process has finished, the controller 6 will be arranged to provide through the pressurisation mechanism 5 a specific pressure pulse or series of pressure pulses of sufficient magnitude to ensure adjustment of the brake arrangement 1 is full and complete prior to topping-up of any brake arrangement reservoirs with brake fluid etc.

It will be understood to ensure there is adequate adjustment for appropriate configuration within the respective slave cylinders 3 that the pressure pulse provided by the pressurisation mechanism 5 should be of sufficient magnitude to exceed the threshold pressure of the respective slave cylinders 3 within the network 4 collectively referred to as the foundation brake. Typically, the threshold pressure of foundation brakes is normally below 2 bar thus, generally, a pressure pulse up to 6 bar will be adequate to ensure full adjustment of the brake arrangement I and in particular correct configuration of the respective slave cylinders 3. It will be understood normally the limiting factor upon pulse pressure will be the inherent damping effect of the hydraulic fluid reservoir associated with - the brake arrangement and in particular the master cylinder 2.

In a second embodiment of the present invention the brake arrangement 1 is adjusted prior to filling with brake fluid. Thus, the master cylinder 2, brake cylinders 3 and pipe network 4 are pressurised using compressed air, or other gas.

A simple seal coupling between the pressurisation mechanism 5 and the master cylinder 2 is provided in order to ensure the brake arrangement I is pressurised to the required level for a specific period of time to ensure displacement of the displaceable piston towards the brake actuator within the respective slave cylinders 3.

As indicated previously, operation of the pressurisation mechanism will be controlled by the controller 6. Thus, a single pressure pulse or plurality of sequential pressure pulses may be provided in order to adjust the brake arrangement 1.

Clearly, with regard to gas pressurisation it is important to ensure the brake arrangement I is not contaminated. Thus, any gas or air supply will be appropriately filtered and passed through a drier before presentation within the brake arrangement I for adjustment of that brake arrangement I in accordance with the present invention. Furthermore, by utilising gas pressurisation it will be appreciated that an appropriate leak detection facility can be provided as it is easier to detect leaks from the brake arrangement 1 with such pressurised gas rather than in a vacuum or through hydraulic fluid leaks. Thus, any leakage to the brake arrangement 1 can be identified and rectified prior to filling the system with brake fluid.

The embodiments of the present invention described above have essentially described in the first embodiment pressurisation of the existing brake fluid and in the second embodiment pressurisation through a gas within the brake arrangement specifically used for brake arrangement 1 adjustment. However, in a third embodiment it will be appreciated that a combination of both fluidic pressure mediums can be used in order to provide brake arrangement 1 adjustment. Thus, after filling the brake arrangement 1, and in particular the master cylinder 2, slave cylinders 3 and pipe network 4, with brake fluid the pressurisation mechanism is arranged to present compressed air to that brake fluid in order to pressurise it. Clearly, to ensure the brake fluid is not dispersed by the compressed air, a simple baffle or deflector is used but essentially the manner of operation is similar to that described with regard to the second embodiment described above. In such circumstances, a single pressure pulse of sufficient magnitude to provide brake adjustment may be used or alternatively a sequence or succession of appropriate pressure pulses may be provided in order to bring the respective slave cylinders 3 into appropriate adjacent component configuration.

With regard to motor vehicle manufacture it is known to use automatic handbrake lever setting devices which trim the handbrake lever by removing any slack within the cable between the handbrake lever and the slave cylinders upon which that lever operates. Thus, in accordance with the present invention it will be appreciated that this automatic handbrake lever setting tool should be interlocked with the present brake adjustment arrangement to ensure that adjustment of the brake arrangement is completed before automatic handbrake lever setting is conducted.

It will be understood that each embodiment described above has its own merits. Thus, the first embodiment requires probably the least adaptation of conventional vehicle manufacturing processes but will add to process time. The second embodiment is a more complete and independent process but will require a greater volume of compressed air and better control. The third embodiment has a reduced pressurisation gas volume but it is necessary that the brake arrangement is filled with brake fluid which will act as an intermediate carrier of pressurisation pulses for adjustment of the brake arrangement and in particular the slave cylinders 3. P Typically, the pressure range for pulses used for brake adjustments according to the present invention will be in the range of between 0 bar and 10 Bar with a preference for the range 0 to 6 Bar. Furthermore, as indicated previously, a single one-shot pressure pulse may be used or alternatively incremental and sequential pressure pulses provided where required dependent upon the specific adjust regime or ratchet arrangement for brake arrangement 1 adjustment or setting. Typically, in the order of 8 to 10 sequential pressure pulses will be used.

With regard to the embodiments in the present invention utilising compressed gas it will be appreciated that the closer the source of such compressed gas is to the master cylinder 2 the less gas compression that is required and it will be also be understood that pressure pulse definition will be more easily achieved.

In such circumstances, it will also be understood that by utilising a pressurisation mechanism 5 rather than an operative that the pressure pulse loading for adjustment will be more consistent and may be more specifically tuned to the ne6essary adjustment regime for the brake arrangement 1.

The pressurisation mechanism 5 and in particular the controller 6 can be configured to ensure that there is always an adequate number of pressure pulses presented to the brake arrangement for adjustment. Any variation between the various adjustment regimes for the brake arrangements 1 should be reduced through the inherent repeatability of adjustment by the controller 6 and pressurisation mechanism 5 combination.

As indicated above, typically the present adjustment regime will included sequential pulse of pressurisation in order to incrementally ratchet the brake arrangement in steps rather than in one step. Thus, lower pulse pressures may be used which are more acceptable for the braking arrangement in terms of the inherent burst pressures of the various arrangement components i.e. the reservoir. As already stated it is known to pressure or vacuum fill brake arrangements but such filling regimes will not ensure adjustment due to their one shot nature and probable low and unevenly distributed pressure pulse.

The present invention also includes a method of brake adjustment in which pulses of pressure of over pressure are presented in the brake arrangement from a pressurisation mechanism. Thus, the present invention also comprises a method of brake actuation adjustment in a master/slave cylinder brake arrangement 5 including; a. coupling a pressurisation device to the master cylinder of the brake arrangement; b. initially applying pressurisation fluid to the arrangement such that any off-set between the displaceable means and the brake actuator for each slave cylinder "is eliminated so that these displaceable means and the actuator are adjacent; and, c. adjusting the arrangement to retain that adjacent configuration between the displaceable means and the brake actuator.

The fluid can be pressurised repeatedly at the same, increasing or decreasing values and at the same or extending or shortening time periods in order to achieve adequate brake arrangement. Thus, particularly where the arrangement includes ratchet adjustment then each pressurisation of the fluid will incrementally step the adjustment to that desired for operational brake performance without overstraining the brake arrangement components in terms of their burst pressure.

Claims (10)

1. A brake adjustment arrangement for a motor vehicle, the arrangement including a master cylinder and a plurality of slave cylinders coupled together through a pipe network, the slave cylinders including displaceable means to provide, in use, a brake function when forced into engagement with a brake actuator by a brake force applied through the pipe network from a brake force applicator whilst said master cylinder is coupled to pressurisation means in order to initially pressurise the pipe work and slave cylinders whereby each displaceable means is initially displaced to be adjacent to its brake actuator to allow adjustment of the brake pulse applicator for direct application of brake force without offset therebetween.

2. An arrangement as claimed in Claim I wherein the pressurisation means is arranged to provide a single pressurisation pulse to the pipe network and slave cylinders through the master cylinder.

3. An arrangement as claimed in Claim I wherein the pressurisation means is arranged to provide a multitude of sequential pressure pulses to the pipe network and slave cylinders through the master cylinder.

4. An arrangement as claimed in any preceding claim wherein the pressurisation means is arranged to present compressed gas to the pipe network and slave cylinders through the master cylinder.

5. An arrangement as claimed in Claim 4 wherein the pressurisation means is a arranged to present the compressed gas to a hydraulic fluid within the pipe network and slave cylinders through the master cylinder.

6. An arrangement as claimed in any of Claims 1 to 3 wherein the pressurisation means is arranged to provide pressurisation of a brake fluid within the pipe network and slave cylinders through the master cylinder.

7. A brake adjustment arrangement substantially as hereinbefore described with reference to the accompanying drawing.

8. A method of brake adjustment in a master and slave cylinder brake arrangement including the steps of:

a) coupling a pressurisation device to the master cylinder of the brake arrangement, b) initially applying pressurisation to the arrangement such that any offset between displaceable means and brake actuation means for each respective slave cylinder is eliminated so that these displacement means and brake actuators are adjacent one another; c) adjusting the arrangement to retain that adjacent configuration between each respective displacement means and its brake actuator.

9. A method as claimed in Claim 8 wherein a multiplicity of sequential pressure pulses is provided to eliminate any off-set between the displaceable means and the brake actuator.

10. A method of brake adjustment in a master and slave cylinder brake arrangement substantially as hereinbefore described with reference to the accompanying drawing.