Device for water injection in a vehicle and method for operating such a device

Abstract

A device (2) for water injection in a vehicle, comprising a water tank (4) connected to a number of injection nozzles (8) via a supply line (10), a delivery mode for delivering water from the water tank (4) via the supply line (10) to the injection nozzles (8), a stationary mode in which the supply line (10) is a closed line system, and a drainage mode for draining the injection nozzles (8) and the supply line (10). A blocking device (16) is arranged along the supply line (10), which is open in delivery mode and closed in stationary mode, for blocking and keeping the supply line (10) dry. A control unit (14) is arranged for activating the blocking device (16) and for switching between the delivery mode and the drainage mode such that the blocking device (16) is opened when the vehicle is parked.and the drainage operation is switched on until the supply line (10) is only filled with air, and then the drainage operation is switched off and the locking device (16) is closed.,

Description

The invention relates to a device for water injection in a vehicle and to a method for operating such a device.A device for water injection is described, for example, | in DE 10 2014 222 463 A1. Further water injections are described in DE 10 2012 207 907 A1, DE 10 2012 206 979 A1 and DE 10. 2014 204 509 A1.For improvement: the operation of an internal combustion engine of a ". It is known to mix water into the fuel. For this purpose, a device for water injection is usually used, also referred to as a als© water injection system. Such a device usually comprises a pump which supplies water from a water container via suitable lines, i.e. via a connecting line, to a number of injection nozzles. By means of the injection nozzles, also referred to as injectors, water is then injected during operation, for example, into the intake tract in the vehicle. After the running operation is ended, water may remain in the injection nozzles and the supply line. In order to prevent damage to the device due to freezing of this water, the device is usually dewatered at the end of travel, for example as described in the aforementioned DE 10 2014 222 463 A1.Against this background, it is an object of the invention to provide an improved device for water injection which is protected in an improved manner against damage by freezing water.The object is achieved by a device having the features according to claim 1 and by a method having the features according to claim 7. The developments and advantages mentioned in connection with the device also apply analogously to the method and vice versa.The device is used for water injection in a vehicle, which in particular has an internal combustion engine for short. The device has a water container which is connected via a feed line to a number of injection nozzles. The device is operable in a delivery mode for delivering water from the water container via the feed line to the injection nozzles, i.e. for injecting water, e.g. into an intake tract of the vehicle. Furthermore, the device can also be operated in a dewatering mode for dewatering the injection nozzles and the feed line, i.e. for removing water from the injection nozzles and the feed line. The dewatering operation and the conveying operation are in particular mutually exclusive, i.e. only one of the two operations can be carried out at a given time. The delivery mode is used in particular exclusively in a driving mode, i.e. when the internal combustion engine is switched on and the vehicle is active.In a stationary operation, the feed line is a line system which is sealed off in particular with respect to the environment, as a result of which no pressure equalization with the environment is possible. In other words: the device is sealed off in particular in a pressure-tight manner when the vehicle is shut down, i.e. in the stationary mode. Die. The supply line is closed off on the one hand by the blocking device and on the other hand by the injection nozzles through which water is injected into the engine during operation, which however are expediently closed during stationary operation. In the stationary mode, the feed line is accordingly terminated in particular by the injection nozzles being closed, in particular since they are not required in the stationary mode and are therefore free of current.In particular, when the blocking device is open, the supply line is closed off on the one hand by the injection nozzles and on the other hand by the water container and thus also greenishally closed off from the environment. In a variant, an air intake for the dewatering operation forms a third end, which is expediently closed off by an air valve when no air is drawn in, i.e. when no dewatering takes place. The closure by the water container is in particular not necessarily pressure-tight, for example if the water container is connected to the environment by a pressure relief valve in an advantageous embodiment. In particular, however, the above-described problem of a possible negative pressure continues to exist.Along the feed line, i.e. in particular between the water container and the injection nozzles, a blocking device is arranged, which is open in the conveying operation and in the dewatering operation and which is closed in the stationary operation, for blocking and keeping the feed line dry. Stationary operation is understood in particular to mean that the internal combustion engine is switched off, for example when the vehicle is parked. In the stationary mode, no injection of water takes place. The blocking device then separates the water container from the injection nozzles.Other openings, for example for the intake of air for the purpose of dewatering in dewatering operation, are also expediently closed at least in standby operation. In the case of such a closed-off feed line, dirt is prevented in a particularly simple manner from penetrating into the device and ultimately blocking the injection nozzles or entering the intake tract or the engine. The blocking device then prevents undesired suction of water from the water container during stationary operation due to a pressure drop within the supply line closed off from the environment. In this respect, a closed-off feed line with a blocking device can safely also be exposed to low temperatures.When the vehicle is shut down, the blocking device is opened and the dewatering mode is switched on until the feed line is only filled with air, i.e. completely dewatered and is thus dry. Subsequently, the dewatering operation is switched off and the blocking device is closed. This ensures first that water possibly accumulated in the feed line is removed before the shut-off, before the feed line is then shut off. The feed line is thus first dried and then shut off. This takes place expediently when the stationary mode is initiated, i.e. when the vehicle is shut down and the stationary mode is activated. The engine is then switched off and the vehicle is, as it were, prepared for the stationary operation by first draining the supply line and then finally shutting it off.The invention is based in particular on the finding that even in the case of a dewatered feed line there is still the problem of possible damage by freezing water. This results in particular from the fact that when the device cools down and because of the completion of the feed line, the pressure in the same feed line drops and water is drawn from the water container into the feed line and possibly up to the injection nozzles. At correspondingly low external temperatures, i.e. below the freezing point of water, there is then the risk of the water unintentionally entering the feed line freezing. The resulting ice pressure can damage in particular the injection nozzles and their valve mechanism, and therefore the entire valve block.In principle, it is possible to heat the supply line in stationary operation in order to avoid a pressure drop. However, this disadvantageously requires energy, which is taken from the battery of the vehicle, for example, and correspondingly contributes to its discharge. Depending on the service life, a correspondingly strong discharge of the battery results.On the other hand, it is clearly more advantageous to use a blocking device which, in the stationary mode, blocks access to the water container and thus prevents water from penetrating in particular in a mechanical manner. An essential advantage of the invention is thus in particular that a. This is because damage to the device by freezing water is effectively and simply prevented in construction. This is achieved by the blocking device which prevents water from penetrating from the water container in the direction of the injection nozzles even if a pressure drop occurs in the feed line due to a cooling of the device. The blocking device acts as a barrier beyond which the water cannot penetrate any further into the feed line. Between the blocking device and the injection nozzles, the feed line is thus kept dry.The blocking device has in particular only two switching states, namely a closed state and an open state. In the open state, water can be conveyed through the blocking device; in the closed state, this is prevented.The blocking device is preferably designed as a shut-off valve. Such a configuration is particularly simple from a constructional point of view and overall also particularly cost-effective. The shut-off valve is in particular a simple valve with two connections which are connected to the feed line, so that the valve divides the feed line into two sections which are separated from one another in the closed state of the shut-off valve.5 Expediently, the blocking device is a separate, i.e. in particular independent, component and can thus be positioned freely along the feed line. In addition, the locking device in this embodiment is also easily retrofitted to existing devices.In a particularly suitable embodiment, the blocking device is electrically switched and closed in the non-energized state and opened in the energized state. For example, the blocking device is an electrically switchable valve. Because the blocking device is closed in the non-energized state, advantageously no energy supply is necessary for the blocking device in the stationary operation when the supply line is to be blocked. Energization is then necessary when the blocking device is opened, i.e. in the conveying operation and in the dewatering operation.Along the feed line, in particular, a pump is arranged for conveying water. The pump has a suction side and a pressure side. In the delivery mode, the suction side of the pump is connected to the water container for the suction of water therefrom. The pressure side is connected to the injection nozzles. In this case, the connections are formed in particular by the feed line. In a preferred embodiment, the suction side and the pressure side are identical in the delivery operation and in the dewatering operation, so that water flows through the pump in the same direction both in the delivery operation and in the dewatering operation. In other words: in the conveying operation, the suction side also corresponds to the suction side in the dewatering operation and the pressure side in the conveying operation also corresponds to the pressure side in the dewatering operation. In other words, in both operations, the pump is operated in the same direction. This makes it possible in particular to dispense with a reverse rotation of the pump. In this way, a dewatering operation is realized in the same direction as the conveying operation. The maintenance of the conveying direction of the pump in both operations advantageously also enables the use of pumps which are not suitable for reverse rotation. A particularly suitable pump is a low cost diaphragm pump and generally a pump which does not require lubrication. In principle, however, any type of pump can be used as the pump, in particular also a piston pump.For switching over between the conveying operation and the dewatering operation, the device has in particular a valve which is preferably not the blocking device or comprises it, but is instead designed as a separate component with respect to it. As a result, the changeover between conveying and dewatering operation is advantageously independent of the shutoff of the feed line. The valve is expediently arranged in such a way that only one pump is required for conveying water and for dewatering. For switching between the conveying operation and the dewatering operation, only the valve is switched. The dewatering operation is then in particular a suck-back operation, i.e. water is sucked back into the water container in the dewatering operation.A valve which is designed as a 4 / 2-way valve is particularly suitable for switching between conveying and dewatering operation. This variant is significantly simplified with regard to the number of valves, in particular only one valve is required for switching over, and thus enables a particularly compact configuration of the device. Variants with other valves, in particular: as described in DE 10 2014 222 463 A1 mentioned at the beginning, are possible in principlePreferably, the blocking device is arranged between the pump and the water container, i.e. on the suction side of the pump in the delivery mode. This advantageously prevents water from being drawn in as far as the pump and damaging the same when freezing. The same pump serves in particular both for conveying water in the conveying operation and for dewatering in the dewatering operation.Particularly advantageous is an embodiment in which the blocking device is arranged between the valve and the water container, so that the supply line can be blocked as effectively as possible, regardless of the switching state of the valve.Overall, it is advantageous to arrange the blocking device as close as possible to the water container in order to block as wide as possible parts of the feed line with respect to the water container. In other words, the blocking device is expediently arranged directly behind the water container. "Direct" is understood in particular to mean that no further components are arranged along the feed line between the water container and the blocking device. Such an optimally close positioning of the blocking device on the water container can be realized in a simple manner in particular if the blocking device is formed as a separate part and can be freely positioned accordingly in the design of the device.The method is used for operating a device for water injection in a vehicle, in particular a device as described above. In a delivery operation, water is delivered from a water container via a feed line to a number of injection nozzles. The supply line is a closed-off line system in a stationary mode. Furthermore, a blocking device is arranged, which is opened in the delivery mode and is closed in the stationary mode, for keeping the feed line between the blocking device and the injection nozzles dry. Keeping dry is understood in particular to mean that water is prevented from penetrating. Preferably, in a dewatering mode, the injection nozzles and the feed line are dewatered. The advantages of the method are derived correspondingly from the advantages of the apparatus described above.The blocking device is preferably opened only in the conveying operation and in the dewatering operation and is otherwise closed. In this way, it is ensured that water can only penetrate if water is also to be conveyed through the feed line and otherwise not. The feed line is thus shut off as standard and is only opened when water is to be injected or sucked back. In particular in the case of a valve which is de-energized in the closed state as a blocking device, the energy requirement of the device is also reduced as a result.Along the feed line, in particular, a pump is arranged, which in a preferred embodiment is switched on in the delivery mode and in the dewatering mode, wherein the blocking device is opened when the pump is switched on and is closed when the pump is switched off. The pump and the blocking device are thus coupled to one another. In other words: if the pump is active, the blocking device is open in order to allow a delivery of water, whereas if the pump is inactive, the blocking device is closed. In this embodiment, the power supply of the pump and the blocking device are expediently coupled to one another, so that when the pump is activated, the blocking device is also energized and correspondingly automatically opened and is otherwise free of flow and automatically closes.A control unit is arranged to actuate in particular the blocking device, the pump and / or the valve for switching between conveying and dewatering operation. This is, for example, an independent control unit of the device, but preferably a part of an engine control of the vehicle.An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. Therein, the single FIG. 1 schematically shows a water injection device for a vehicle.FIG. 1 shows a device 2 for water injection, i.e. a water injection system. The device 2 has a water container 4, from which water is pumped by means of a pump 6 to a number of injection nozzles 8 in the delivery mode. The water is conveyed via a feed line 10, along which the pump 6 is arranged. For switching between the delivery mode and a dewatering mode, a valve 12 is arranged along the feed line 10 between the water container 4 and the pump 6. This is connected to a suction side 6A and a pressure side 6B of the pump 6. In the exemplary embodiment shown, the changeover between conveying operation and dewatering operation is realized by a single 4 / 2-way valve 12.FIG. 1 shows the device 2 in a delivery mode in which the suction side 6A is connected to the water container 4 and the pressure side 6B is connected to the injection nozzles 8, In the dewatering mode, the suction side 6A is connected to the injection nozzles 8 and the pressure side 6B is connected to the water container 4. In this operation, the pump 6 then delivers air in the direction of the injection nozzles 8, as a result of which the feed line 10 and the injection nozzles 8 are dewatered and dried.When the vehicle is shut down, it is possible for the feed line 10 to cool, as a result of which a reduced pressure is generated and water is drawn from the water container 4 into the feed line 10 and in the direction of the injection nozzles 8. At low external temperatures of below 0° C., there is then the risk that this water will freeze and that the feed line 10 and / or the injection nozzles 8 8 will be damaged. In order to prevent this, a blocking device 16 is arranged along the feed line 10, which is designed here as a shut-off valve. The blocking device 16 is then closed in the stationary mode, so that no water is sucked into the feed line 10 despite a possibly low temperature.A particularly comprehensive protection of the feed line 10 is achieved in that the blocking device is arranged as close as possible and, as shown in FIG. 1, directly behind the water container 4 and still in front of the pump 6 and the valve 12. The blocking device 16 is furthermore designed as a separate part and is not integrated into the pump 6 or the valve 12. In particular, the blocking device 16 can thereby be operated independently of the valve 12.List of reference characters2 Device for water injection 4 Water container 6 Pump 6A Suction side 6B Pressure side 8 Injection nozzle 10 Feed line 12 Valve 14 Control unit 16 Blocking device

Claims

Device (2) for water injection in a vehicle, having a water container (4) which is connected via a feed line (10) to a number of injection nozzles (8), having a conveying operation, for conveying water from the water container (4) via the feed line (10) to the injection nozzles (8), having a stationary operation, in which the feed line (10) is a closed-off line system, having a dewatering operation, for dewatering the injection nozzles (8) and the feed line (10), wherein a blocking device (16), which is open in the conveying operation and which is closed in the stationary operation, is arranged along the feed line (10) for blocking and keeping the feed line (10) dry, wherein a control unit (14) is arranged for starting the blocking device (16) and for switching between the conveying operation and the dewatering operation in such a way, wherein the blocking device (16) is opened when the vehicle is shut off and the dewatering mode is activated until the feed line (10) is only filled with air, and subsequently the dewatering mode is deactivated and the blocking device (16) is closed.Device (2) according to the preceding claim, characterized in that the blocking device (16) is designed as a shut-off valve.Device (2) according to one of the preceding claims, characterized in that the blocking device (16) is designed as a separate component.Device (2) according to one of the preceding claims, characterized in that the blocking device (16) is electrically switchable and is closed in the non-energized state and is open in the energized state.Device (2) according to one of the preceding claims, characterized in that a pump (6) is arranged along the feed line (10), and in that the blocking device (16) is arranged between the pump (6) and the water container (4).Device (2) according to one of the preceding claims, characterized in that the blocking device (16) is arranged directly behind the water container (4).Method for operating a device (2) for water injection in a vehicle, - wherein in a delivery operation water is delivered from a water container (4) via a feed line (10) to a number of injection nozzles (8), - wherein the feed line (10) is a closed-off line system in a standing operation, - wherein a blocking device (16) is arranged, which is opened in the delivery operation and is closed in the standing operation, for keeping the feed line (10) between the blocking device (16) and the injection nozzles (8) dry, - wherein in a dewatering operation the injection nozzles (8) and the feed line (10) are dewatered, and - wherein when the vehicle is shut down the blocking device (16) is opened and the dewatering operation is switched on until the feed line (10) is filled only with air, and subsequently the dewatering mode is switched off and the blocking device (16) is closed.Method according to the preceding claim, characterized in that the blocking device (16) is opened only in the conveying operation and in the dewatering operation and is otherwise closed.Method according to either of Claims 7 and 8, characterized in that a pump (6) is arranged along the feed line (10), and in that the blocking device (16) is opened when the pump (6) is switched on and is closed when the pump (6) is switched off.

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