Patent Description:
The present invention additionally is directed to a testing system for assessing a quality parameter of a brake fluid.

The present invention also relates to a test device for such a testing system.

Moreover, the present invention is directed to a vehicle.

Furthermore, the present invention relates to a method for assessing a quality parameter of a brake fluid.

A brake system is an essential part of a vehicle ensuring safe operation thereof.

<CIT> discloses a multiple-circuit hydraulic brake system, in particular for automotive vehicles. The brake system comprises a servo-assisted brake-actuating device supplied with servo pressure from a supply system, several pressurisable working chambers for pressurisation of wheel-brake cylinders and a fast-fill cylinder inserted into a brake circuit. One end compartment of the fast-fill cylinder is connected via pressure lines to one pressure chamber of the brake-actuating device and the other end compartment of the fast-fill cylinder is connected by line to a brake line leading from the brake-actuating device to at least one wheel cylinder. A normally-open controlled non-return valve is arranged in the pressure line which valve closes its pressure-fluid passage upon failure of the servo supply system pressure acting in the pressure line and/or upon a sufficient rise of the pressure in the one working chamber and thus hydraulically locks the stepped piston of the fast-fill cylinder preventing displacement of the piston.

Known brake systems use a brake fluid in order to transfer a braking request from a brake pedal unit or a master cylinder unit to the actual brakes of the vehicle, i.e. the components actually decelerating the vehicle's wheels. Thus, it is important to ensure at all times that a quality of the brake fluid allows for a reliable operation of the braking system. In other words, all relevant quality parameters of the brake fluid need to be in a corresponding desired range.

This may be done by regularly changing the brake fluid.

In this context, a relevant quality parameter of the brake fluid is the water content. Thus, it has to be ensured that the water content of the brake fluid does not exceed a predefined threshold, e.g. <NUM>% of the volume of the brake fluid.

Instead of regularly changing the brake fluid, it is also known to change the brake fluid based on a measurement of the desired quality parameter of the brake fluid using a measurement apparatus. However, such measurement apparatuses are often complicated in use, especially if a relatively precise measurement result is needed. Alternatively, relatively simple measurements are usually not be precise enough.

It is an objective of the present invention to improve the assessment of a quality parameter of a brake fluid such that the quality parameter may be determined in a simple and reliable manner. The quality parameter is for example the water content.

The problem is at least partially solved or alleviated by the subject matter of the independent claims of the present invention, wherein further examples are incorporated in the dependent claims.

According to a first aspect, there is provided a brake system component for a vehicle. The brake system component comprises a channel for guiding a brake fluid and a sample outlet module for withdrawing a brake fluid sample from the channel. The sample outlet module is fluidically connected to the channel. Moreover, the sample outlet module comprises a non-return valve having a blocking direction being directed towards an environment of the sample outlet module. The sample outlet module also comprises a thrust piece for selectively opening the non-return valve. Using the sample outlet module, a brake fluid sample can be taken from the brake system component in a simple manner. To this end, the non-return valve may be opened by operating the thrust piece. Thus, the brake fluid sample can be withdrawn without the need to use tools. Moreover, it is not necessary to dismount parts in order to withdraw a brake fluid sample. Due to the properties of a non-return valve, the sample outlet module is reliably sealed with respect to the environment, if it is not used, i.e. if no brake fluid sample is withdrawn from the sample outlet module. Consequently, undesired leakage of brake fluid is reliably avoided.

In an example, the non-return valve comprises a spring-biased valve element. The valve element may be ball-shaped. In order to open such a valve, the valve element has to be pushed against the spring bias. Such non-return valves are structurally simple and may be operated in a reliable manner.

In an example, the thrust piece comprises a sampling channel for guiding the brake fluid sample to the environment. In this context, the sampling channel connects the channel and the environment if the non-return valve is in an open condition. If the non-return valve is closed, the sampling channel is blocked such that the channel and the environment are fluidically separated from one another. Thus, using a sampling channel, a brake fluid sample may be reliably withdrawn from the channel, if desired. Otherwise, the channel is reliably sealed with respect to the environment.

In an example, the thrust piece comprises a reservoir for receiving a predefined quantity of brake fluid. In this case, the reservoir may be filled with brake fluid if the non-return valve is opened. Then, the brake fluid may be withdrawn from the reservoir as a brake fluid sample. This has the effect that a quantity of the brake fluid sample is defined by the volume of the reservoir. This further facilitates taking a brake fluid sample from the brake system component.

In an example, the thrust piece comprises a hollow needle for fluidically connecting the thrust piece to a test device. In this context, the hollow needle may be fluidically connected to the reservoir and/or to the sampling channel. The test device may be a device for receiving the brake fluid sample and/or for analyzing the brake fluid sample. Using the hollow needle allows to reliably transfer the brake fluid sample to the test device.

In an example, the sample outlet module comprises a protection collar extending around the hollow needle and protruding over the hollow needle along a length direction of the hollow needle. This has the effect that an unintentional contact of a human being or a device with the hollow needle is blocked. Consequently, potential injuries of the human being and damages on the device are avoided.

In an example, the thrust piece comprises a pressure surface for applying a motive force to the thrust piece. Thus, the thrust piece can be reliably moved such that the non-return valve can be reliably opened and/or closed. In an exemplary case, the thrust piece is moved such that it acts on a valve element of the non-return valve against its blocking direction.

In an example, the hollow needle extends from the pressure surface. This configuration makes it simple to ensure that an appropriate test device is provided before the thrust piece is operated and the non-return valve is open.

In an example, the hollow needle extends from a center of the pressure surface.

In an example, the channel and the sample outlet module are coupled via a pair of mutually engaged screw threads. In simplified words, the sample outlet module is screwed into the part forming the channel. Thus, the channel and the sample outlet module may be coupled in a simple and reliable manner. The sample outlet module, more precisely the screw thread of the sample outlet module, may also be configured to be able to interact with known screw threats on the part comprising the channel.

In an example, the screw thread of the sample outlet module may have the same properties and dimensions as a known air screw. Consequently, a known air screw of a brake system component may be replaced by the sample outlet module. This has the effect that the sample outlet module may be retro-fitted to known brake system components.

In an example, the brake system component is a brake caliper or a brake system pipe or a pipe fitting. Consequently, using the sample outlet module, a brake fluid sample can be withdrawn from the brake caliper or the brake system pipe or a pipe fitting. The pipe fitting may also be called a connector part.

In an example in which the quality parameter to be assessed is a water content of the brake fluid, it is especially useful if the brake system component is a brake caliper. This is due to the phenomenon that within a brake system, usually, the highest water content occurs at the brake calipers. Thus, it can be ensured that the water content of the brake fluid stays below a predefined threshold with high reliability.

According to a second aspect, there is provided a testing system for assessing a quality parameter of a brake fluid. The testing system comprises a brake system component of the present invention and a test device. The test device comprises a receptacle and an operating surface for selectively operating the thrust piece, wherein an indicator fluid is provided in the receptacle. In other words, the thrust piece may be operated using the test device. Thus, by applying the test device to the thrust piece, the non-return valve is opened and the brake fluid sample is withdrawn from the channel. This has the effect that the brake fluid sample is directly led to the test device. The indicator fluid in the receptacle of the test device is adapted to the quality parameter of the brake fluid to be assessed. Altogether, the brake fluid sample may be directly led into the receptacle and may directly interact with the indicator fluid provided therein. Consequently, the quality parameter of the brake fluid may be assessed with high precision. At the same time, especially since the brake fluid sample does not need to be handled between the brake system component and the test device, withdrawing the brake fluid sample is simple.

In an example, the indicator fluid comprises anhydrous copper (II) or an acid with a pH indicator. Such an indicator fluid is especially suitable for assessing a water content of the brake fluid. The water content can be assessed by observing a color change of the indicator fluid. It is noted that an indicator fluid comprising anhydrous copper (II) may need to be stoichiometrically adapted to the specific type of brake fluid being used. In a case in which the brake fluid comprises borates and an indicator fluid comprising an acid with a pH indicator is used, the indicator fluid needs to be balanced to the specific borate content.

In an example, the receptacle may be formed as a vial. Especially, the vial may be of the CG-MS type.

According to a third aspect, there is provided a test device for a testing system according to the present invention. The test device comprises a receptacle and an operating surface for selectively operating the thrust piece, wherein an indicator fluid is provided in the receptacle. Using such a test device, a quality parameter of the brake fluid may be assessed in a simple and reliable manner. As has been explained before, the indicator fluid is adapted to the quality parameter to be assessed.

In an example, the receptacle is sealed with a pierceable sealing means. This is especially suitable if the sampling module comprises a hollow needle. In such a case, the hollow needle may pierce the sealing means in order to transfer the brake fluid sample into the receptacle, i.e. to mix the brake fluid sample with the indicator fluid.

In an example, the sealing means is a membrane or a foil covering an opening of the receptacle.

In an example, an inert gas is provided in the receptacle. In this context, the indicator fluid and the inert gas fully fill the receptacle. In other words, no air or other substances than inert gas and indicator fluid are present in the receptacle. This has the effect that undesired chemical or physical reactions of the indicator fluid are avoided. Consequently, the test device has a long shelf life.

According to a fourth aspect, there is provided a vehicle comprising a brake system having a brake system component of the present invention. Thus, using the sample outlet module, a brake fluid sample can be taken from the brake system component in a simple manner as has already been described above. Due to the properties of the non-return valve, the sample outlet module is reliably sealed with respect to the environment, if it is not used, i.e. if no brake fluid sample is withdrawn from the sample outlet module. Consequently, undesired leakage of brake fluid is reliably avoided. Altogether, a quality of the brake fluid of the vehicle can be checked in a simple and reliable manner.

In an example, the sample outlet module is arranged at a right rear brake caliper or in proximity to a right rear caliper if the vehicle is a left-handed vehicle. In a case in which the vehicle is a right-handed vehicle, the sample outlet module may be arranged at a left rear brake caliper or in proximity thereto. This arrangement is especially advantageous if the quality parameter to be assessed is a water content. The highest water content is usually measured at the brake calipers and, more precisely, the brake caliper being most remote from the master cylinder unit of the brake system. This is the case for the right rear brake caliper in a left-handed vehicle and the left rear caliper in a right-handed vehicle. Thus, by guaranteeing that the quality parameter is within the desired boundaries at these locations, the overall quality of the brake fluid is ensured.

In an example, the sample outlet module is arranged on the vehicle such that it can be accessed without dismounting any part of the vehicle, especially without needing to dismount a wheel.

According to a fifth aspect, there is provided a method for assessing a quality parameter of a brake fluid. The method comprises:.

This means that the non-return valve is temporarily opened by pressing the test device against the thrust piece. Consequently, the brake fluid sample is directly led into the receptacle of the test device. The observed property of the indicator fluid is for example a color of the indicator fluid. Based on a color change, the quality parameter of the brake fluid may be assessed. For performing this method, other than the brake system component of the present invention, only a test device of the present invention is needed. Put otherwise, no tools or further machinery is needed in order to perform the method. Consequently, the method is simple. At the same time, it can be performed practically anywhere, e.g. on a parking lot. At the same time, the assessment of the quality parameter is highly precise. This is mainly due to the fact that the brake fluid sample is directly mixed with the indicator fluid of the test device. Due to the fact that the test device is directly applied to the sampling module, the potential of contaminating the brake fluid sample while being transferred from the channel of the brake system into the test device is very small. Also the fact that for each brake fluid sample, a new test device may be used, renders the quality assessment precise and reliable.

These and other aspects of the present invention will become apparent from and elucidated with reference to the examples described hereinafter.

Examples of the invention will be described in the following with reference to the following drawings.

The Figures are merely schematic representations and serve only to illustrate examples of the invention.

<FIG> shows a vehicle <NUM> having four wheels 12a, 12b, 12c, 12d.

In the present example, wheels 12a and 12b form front wheels and wheels 12c and 12d form rear wheels.

The forward driving direction of the vehicle <NUM> is indicated by arrow D.

A brake disc 14a, 14b, 14c, 14d is connected to each of the wheels 12a, 12b, 12c, 12d respectively.

Moreover, a brake caliper 16a, 16b, 16c, 16d is associated to each of the brake discs 14a, 14b, 14c, 14d. This means that each of the brake calipers 16a, 16b, 16c, 16d is configured to frictionally engage the associated brake disc 14a, 14b, 14c, 14d in order to decelerate the wheel 12a, 12b, 12c, 12d to which the associated brake disc 14a, 14b, 14c, 14d is connected.

The vehicle <NUM> additionally comprises a master cylinder unit <NUM> and a brake pedal unit <NUM>. The brake pedal unit <NUM> is connected to the master cylinder unit <NUM>.

Moreover, each of the brake calipers 16a, 16b, 16c, 16d is fluidically connected to the master cylinder unit <NUM> via an associated brake system pipe 22a, 22b, 22c, 22d.

The brake discs 14a, 14b, 14c, 14d, the brake calipers 16a, 16b, 16c, 16d, the master cylinder unit <NUM>, the brake pedal unit <NUM> and the brake system pipes 22a, 22b, 22c, 22d together form a brake system <NUM>. The brake system pipes 22a, 22b, 22c, 22d may be connected to the respective brake calipers 16a, 16b, 16c, 16d by respective pipe fittings which also form part of the brake system <NUM>.

Thus, the brake calipers 16a, 16b, 16c, 16d, the master cylinder unit <NUM>, the brake pedal unit <NUM>, each of the brake system pipes 22a, 22b, 22c, 22d and each of the pipe fittings may also be referred to as a brake system component <NUM>.

In the following, the term brake system component <NUM> refers to the brake caliper 16d which is the brake caliper being associated to the right rear wheel 12d.

The brake caliper 16d, i.e. the brake system component <NUM>, is shown in more detail in <FIG>.

The brake system component <NUM> comprises a channel <NUM> for guiding a brake fluid BF.

More precisely, using the channel <NUM>, pressurized brake fluid BF may be guided to a piston which is connected to a brake pad in order to frictionally engage the corresponding brake disc 14d with the brake pad. This is generally known and, therefore, will not be explained in further detail.

On the brake system component <NUM>, i.e. on the brake caliper 16d, a threaded hole <NUM> is provided and a sample outlet module <NUM> is connected to the brake caliper 16d via the threaded hole <NUM>.

More precisely, the sample outlet module <NUM> comprises a threaded portion <NUM> which threadingly engages the threaded hole <NUM>.

In the present example, the threaded hole <NUM> has originally been configured to receive an air screw. Thus, the air screw has been replaced by the sample outlet module <NUM>.

The sample outlet module <NUM> is fluidically connected to the channel <NUM>.

Moreover, the sample outlet module <NUM> comprises a sampling channel <NUM> for selectively guiding a brake fluid sample to an environment of the brake system <NUM>.

At an end of the sampling channel <NUM> being remote from the channel <NUM>, a non-return valve <NUM> is arranged. The non-return valve <NUM> has a blocking direction being directed towards the environment of the sample outlet module <NUM>.

This means, that in a non-actuated condition of the non-return valve <NUM>, brake fluid BF cannot leave the brake system <NUM>, more precisely the channel <NUM> or the sample outlet module <NUM>.

In the present example, the non-return valve <NUM> comprises a ball-shaped valve element which is spring-biased against a conical valve seat.

The sample outlet module <NUM> also comprises a thrust piece <NUM>. The thrust piece <NUM>, the valve element of the non-return valve <NUM> and the sampling channel <NUM> are arranged coaxially.

Moreover, the thrust piece <NUM> is guided within the sample outlet module <NUM> such that it can only move in parallel a middle axis of the sampling channel <NUM>.

The thrust piece <NUM> is configured to selectively open the non-return valve <NUM>.

To this end, the thrust piece <NUM> comprises a main body with a reservoir <NUM> and a thrust collar <NUM> extending therefrom towards the valve element of the non-return valve <NUM>. An end of the thrust collar <NUM> abuts against the valve element <NUM>. Moreover, a plurality of thrust collar openings <NUM> are provided in the thrust collar <NUM>.

On a side opposite the thrust collar <NUM>, the thrust piece <NUM> comprises a pressure surface <NUM>.

In order to open the non-return valve <NUM>, a motive force may be applied to the pressure surface <NUM> and the thrust piece <NUM> may be moved in an opening direction of the non-return valve <NUM>. Thereby, the thrust piece <NUM> opens the non-return valve <NUM> by lifting the valve element form the valve seat. Consequently, a fluidic connection is created between the channel <NUM> and the reservoir <NUM>. In more detail, brake fluid BF can flow from the channel <NUM> through the sampling channel <NUM>, around the valve element and into the thrust piece <NUM> via the thrust collar openings <NUM> in order to reach the reservoir <NUM>.

Beyond that, the thrust piece <NUM> comprises a hollow needle <NUM> which is configured to fluidically connect the thrust piece <NUM> to a test device as will be explained later.

The hollow needle <NUM> extends from a center of the pressure surface <NUM>.

Consequently, the thrust collar openings <NUM>, the reservoir <NUM> and the hollow needle <NUM> may also be referred to as a sampling channel <NUM> of the thrust piece <NUM>.

In order to protect the hollow needle <NUM> from undesired contacts with other elements or humans, a protection collar <NUM> is provided on the sample outlet module <NUM>. The protection collar <NUM> extends coaxially to the hollow needle <NUM> and protrudes over the hollow needle <NUM> along a length direction of the hollow needle <NUM>.

Altogether, the sample outlet module <NUM> can be used for withdrawing a brake fluid sample from the channel <NUM>. This will be explained in more detail below.

In this context, the brake system component <NUM>, i.e. the brake caliper 16d comprising the sample outlet module <NUM> forms part of a testing system <NUM> for assessing a quality parameter of the brake fluid BF.

In the present example, the quality parameter to be assessed is the water content of the brake fluid BF.

A further component of the testing system <NUM> is a test device <NUM>.

The test device <NUM> is shown in more detail in <FIG>. Moreover, the test device <NUM> is indicated with dashed lines in <FIG>.

The test device <NUM> comprises a receptacle <NUM> which generally has the form of a bottle.

The receptacle <NUM> has a receptacle opening <NUM> which is delimited by a rim.

The receptacle opening <NUM> is sealed by a pierceable sealing means <NUM> which in the present example is a membrane. The membrane <NUM> is impermeable with respect to ambient air, but can be pierced using the hollow needle <NUM>.

On the rim of the receptacle <NUM>, which may be covered by the pierceable sealing means <NUM>, there is provided a ring-shaped operating surface <NUM>.

The operating surface <NUM> is configured to contact the pressure surface <NUM> of the thrust piece <NUM>.

Furthermore, in the interior of the receptacle <NUM>, there is provided an indicator fluid IF and inert gas IG.

The indicator fluid IF and the inert gas IG completely fill the interior of the receptacle <NUM>, i.e. no other substances are present therein.

Consequently, a water content of the brake fluid BF of the brake system <NUM> can be assessed using a testing system <NUM> comprising the brake system component <NUM> and the test device <NUM>.

A method for assessing a quality parameter over brake fluids, thus comprises the following steps.

In a first step, the brake system component <NUM> and the test device <NUM> are provided.

In a subsequent, second step, the non-return valve <NUM> is temporarily opened by applying a motive force to the thrust piece <NUM> via the operating surface <NUM> of the test device <NUM>.

This means that the test device <NUM> is located adjacent to the thrust piece <NUM> such that the operating surface <NUM> contacts the pressure surface <NUM>. When doing so, the hollow needle <NUM> pierces the pierceable sealing means <NUM>. In simplified words, the non-return valve <NUM> is opened by pushing the rim of the bottle-shaped test device <NUM> against the thrust piece <NUM>.

Due to the opening of the non-return valve, a fluid connection is provided between the channel <NUM> and the inside of the receptacle <NUM>. Consequently, a brake fluid sample is received inside the receptacle <NUM> in a third step S3. This brake fluid sample flows from the channel <NUM> through the sampling channel <NUM>, circumvents the valve element, flows through the thrust collar opening <NUM>, through the reservoir <NUM> and through the hollow needle <NUM> until it reaches the interior of the receptacle <NUM>.

In the interior of the receptacle <NUM>, the brake fluid sample interacts with the indicator fluid IF.

In the present example, the indicator fluid is an acid with a pH indicator which changes color as a function of the water content of the brake fluid BF.

Consequently, in a fourth step, a change of the color of the indicator fluid IF may be observed. Based on the color change, a water content may be assessed.

It is noted that the non-return valve <NUM> is just opened for a relatively short time, until a relatively small quantity of the brake fluid BF is received inside the receptacle <NUM>. To this end, the test device <NUM> is pushed against the thrust piece <NUM> for a relatively short time, for example <NUM> second.

Claim 1:
A brake system component (<NUM>) for a vehicle (<NUM>), comprising a channel (<NUM>) for guiding a brake fluid (BF) and a sample outlet module (<NUM>) for withdrawing a brake fluid sample from the channel (<NUM>),
wherein the sample outlet module (<NUM>) is fluidically connected to the channel (<NUM>),
wherein the sample outlet module (<NUM>) comprises a non-return valve (<NUM>) having a blocking direction being directed towards an environment of the sample outlet module (<NUM>), and
wherein the sample outlet module (<NUM>) comprises a thrust piece (<NUM>) for selectively opening the non-return valve (<NUM>).