Water discharge device

A water discharge device may include a water collection chamber including a water drainage valve. At least one water sensor may be arranged in a region of the water collection chamber for determining a water level in the water collection chamber and for controlling the water drainage valve. A device may be configured to maintain the water sensor in contact with the water by keeping a water level artificially high in the region of the water collection chamber at the water sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application 10 2010 022 195.3, filed on May 20, 2010, and International Patent Application PCT/EP2011/058034, filed on May 18, 2011, both of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a water discharge device, in particular in a fuel tank or in a filtration device. The invention also relates to a filtration device having such a water discharge device.

BACKGROUND

Fuel for internal combustion engines is usually filtered first before it is fed to the actual combustion process. The water contained in the fuel can damage the internal combustion engine itself or parts thereof, such as an injection system, for example by oxidation of metal parts, for which reason fuel filters are usually used, which are intended to filter out the highest possible proportion of the water contained in the fuel. In known fuel filters, a water collection chamber is arranged in the lower region, in which chamber the water collects owing to its higher specific density compared to fuel. At predefined times, or when predefined levels are reached, the water collection chamber is emptied and the water situated therein is drained. The disadvantage of known fuel filters is however that contamination of the environment with fuel can occur if a water discharge device for draining the water from the water collection chamber incorrectly detects a water level.

SUMMARY

The present invention is concerned with the problem of creating a water discharge device which in particular reduces the risk of contamination of the environment with hazardous substances such as fuel.

This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims.

The present invention is based on the general concept of, in a water discharge device having a water collection chamber and at least one water sensor for determining a water level in the said water collection chamber, arranging at least one water sensor in the water collection chamber in such a manner that it only comes into contact with water, i.e. in particular never with fuel or oil, under normal operating conditions. The at least one water sensor is arranged according to the invention in a bottom region of the water collection chamber, a device also being provided which keeps a water level artificially high in the region of the at least one water sensor and thereby ensures that the water sensor comes into contact with water under normal operating conditions, for example also during cornering or tilted positions up to 45°. The device according to the invention thus ensures that the water sensor is in contact with water in all operating states and thus in particular prevents malfunctions which [result in] an unintentional and undesirable drainage of oil or fuel. Such a device can for example be formed as a bottom sink in which the at least one water sensor is arranged. Then, what is known as a subvolume is provided in the bottom sink, which subvolume is only filled with water, as a result of which it can be ensured that the at least one water sensor is always in contact with water. A corresponding water drain is arranged on a bottom of the bottom sink. The water collected in the water collection chamber is drained at predefined time intervals and is stopped immediately if the at least one water sensor loses contact with water. Owing to the water which is still present in the bottom sink, however, a residual volume is always ensured in the water collection chamber, so it can reliably be ruled out that fuel or oil is inadvertently drained and contaminates the environment. In this connection, fuel or oil is often mentioned, so the water discharge device according to the invention can be arranged for example in a fuel tank or in a filtration device. Arrangement in any other apparatus, in which a heavy first fluid collects at the bottom, which fluid should be separated by drainage from a second fluid lying above it, is however of course also conceivable. Alternatively to the just proposed device, it can also be formed as a wall contour which at least partially surrounds the at least one water sensor, the said wall contour likewise ensuring that the water sensor stays in contact with the water or the first fluid to be separated out in all conceivable operating states. During driving off road, the wall contour also serves as splash protection to prevent ingress of fuel/diesel into a drainage line through the subvolume. When the liquid level is calm, the risk only exists if a tilted position of 45° is exceeded. During driving, however, the dynamics of all the liquid when there is no wall contour can result in flooding of the drainage line with diesel.

In an advantageous development of the solution according to the invention, the water sensor is configured to switch a valve device, by means of which water can be drained if required. The valve device is for example formed as an electric drainage valve and is opened either at certain time intervals or by the signal of a second water sensor. The valve device is closed immediately if the at least one water sensor begins to lose contact with the water collected in the water collection chamber. A loss of this contact indicates a reduction in the water level in the water collection chamber to below a predefined, in particular critical, limit value.

Further important features and advantages of the invention result from the sub-claims, from the drawings and from the associated description of the figures on the basis of the drawings.

It is to be understood that the previously mentioned features and the features which are still to be mentioned in the following, can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the context of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the drawings and are described in more detail in the description below, identical reference numbers referring to identical or similar or functionally identical components.

DETAILED DESCRIPTION

According toFIGS. 1 and 2, a water discharge device1according to the invention, which can be arranged in particular in a fuel tank or in a filtration device generally shown at11, has a water collection chamber2and at least one water sensor3for determining a water level5in the water collection chamber2and for controlling a water drainage valve. The at least one water sensor3is arranged in the bottom10of the water collection chamber2, above the water drainage valve8or a water drain9, a device4being provided which keeps a water level artificially high in the region of the at least one water sensor3and thereby ensures that the water sensor3remains in contact with the water to be drained under all conceivable operating conditions.

The device4can according to the invention be formed as a bottom sink6in which the at least one water sensor3is arranged. In addition or alternatively, the device4according to the invention can also be formed as a wall contour7which at least partially surrounds the at least one water sensor3, it being ensured independently of the configuration of the device4that the water level5in the water collection chamber2and in particular around the water sensor3does not fall below a predefined, undesirable limit value. During driving off road, the said wall contour7also serves as splash protection to prevent ingress of fuel into a drainage line through the subvolume. When the liquid level is calm, the risk only exists if a tilted position of 45° is exceeded. During driving, however, the dynamics of all the liquid if there is no wall contour7can result in flooding of the drainage line with fuel, which can lead to undesirable contamination of the environment.

The at least one water sensor3can be configured to switch the water drainage valve8(not shown in detail) by means of which water can be drained out of the water collection chamber2if required. It is also conceivable for a further, likewise not shown water sensor to be provided, which is situated above the at least one water sensor3and is configured to open the water drainage valve8if it detects water. The drainage process is continued until the water sensor3arranged in the bottom10of the water collection chamber2begins to lose contact with the water. Owing to the water volume being kept artificially high around the water sensor3, it can reliably be ensured that, when the at least one water drainage valve8is closed, no more fluid, in particular no fuel or oil, is drained as well, thereby making contamination of the environment likely. The drainage line, in which the at least one water drainage valve8is arranged, is arranged below the at least one water sensor3.

The valve device8can for example be opened electrically, but closed mechanically, in particular by means of a spring, as a result of which what is known as a fail-safe principle can be realised, which ensures that unintended drainage and thus contamination of the environment can be reliably avoided, in particular in the case of a power failure. The water discharge device1also ensures reliable detection of the water level5during cornering or tilting of a vehicle if the water discharge device1according to the invention is arranged for example in a fuel filter or fuel tank11of the vehicle.

Generally, a water collection chamber2and a water discharge device1is mentioned in both the claims and the description, it being of course clear that this restriction only represents one possible field of use, so the water discharge device1according to the invention can generally also be used for separating a first, heavy fluid from a second, comparatively lighter fluid. The main field of use for the water discharge device1according to the invention is however a fuel filter or an oil filter or a fuel tank11in a motor vehicle. The device4according to the invention can be formed in a cost-effective manner, regardless of whether it is a sink6or a wall contour7, so the significant advantages of the invention can be achieved at comparatively low cost. The sink6or the wall contour7, i.e. the device4, can in particular be produced together with the water collection chamber2, for example using a plastic injection moulding method.