DE102017200046A1 - Water injection apparatus - Google Patents

Abstract

The present invention relates to a water injection device (1) of an internal combustion engine comprising a water tank (5) for storing water, a conveying element (3) for conveying the water, at least one water injector (6) for injecting water, which is connected to the conveying element (3 ), a recognition and / or determination device (14) and a control unit (10). The detection and / or determination device (14) is set up, a need for cooling the water injector (6) and / or another water-carrying component of the water injection device (1) from vapor formation outside operating ranges of the internal combustion engine (2) in which a combustion-related Water injection is necessary to determine. The control unit (10) is arranged to control the water injector (6) for injecting water when a result of the determination by the detection and / or determination device (14) is positive.

Description

State of the art

The present invention relates to a water injection device of an internal combustion engine and such an internal combustion engine. Another aspect of the invention relates to a method of operating such a water injection device.

Due to increasing demands on reduced carbon dioxide emissions, internal combustion engines are increasingly being optimized with regard to fuel consumption. However, known internal combustion engines can not be optimally operated in terms of consumption at operating points with high load, since the operation is limited by knock tendency and high exhaust gas temperatures. A possible measure to reduce the tendency to knock and to lower the exhaust gas temperatures is the injection of water. There are usually separate water injection systems available to allow the water injection. For example, from the WO 2014/080266 A1 a water injection system for an internal combustion engine with exhaust gas recirculation, in which the water is injected into the mass flow of the exhaust gas recirculation.

Between the operating points where the water injection system is activated, the pump used to convey the water is switched off. This means that the water is in the injectors and the lines of the water injection system. Due to the high temperatures of the parts of the internal combustion engine in the vicinity of the water injection system, the standing water can heat up and possibly evaporate. This effect is exacerbated when driving at high altitude, where the air pressure is lower. The formation of steam can lead to functional impairments when restarting the water injection system, since the system pressure can only be built up by the steam with a delay. Thus, the water injection system is delayed ready for operation. Due to this delayed operational readiness, temperature peaks in the exhaust gas as well as knocking events during combustion can occur during rapid load transients. Furthermore, the evaporating water can lead to possible deposits and thus to permanent functional impairments and / or damage to the components, in particular of the injection valve.

Disclosure of the invention

The water injection device according to the invention with the features of claim 1 has the advantage that a timely action is taken to protect the water injector and / or another water-bearing component of the water injection device from wear. "Timely" means that there was no steam until the action was taken. This is inventively achieved by a water injection device of an internal combustion engine having a water tank for storing water, a conveying element for conveying the water, at least one water injector for injecting water, which is connected to the conveying element, a detection and / or determination device, and a Control unit comprises. In this case, the detection and / or determination device is set up to determine a need for cooling the water injector and / or another water-carrying component of the water injection device from formation of steam outside operating ranges in which combustion-related water injection is necessary. If a result of the determination by the detection and / or determination means is positive, the control unit is arranged to control the water injector for injecting water. A positive result of the determination by the detection and / or determination means means that it has been determined that a cooling of the water injector and / or the other water-bearing component of the water injection device is necessary. The cooling can be effected by the water present in the water injector and / or in the other water-carrying component of the water injection device and / or in the line region between the conveying element and the water injector and / or by the conveying element from the water tank. It should be noted that determining the need for cooling also includes detecting the need. In other words, the detection and / or determination device is set up to determine a need for cooling the water injector and / or another water-carrying component of the water injection device against the formation of steam in operating areas in which a combustion-relevant water injection is not necessary. Preferably, the operating ranges in which water injection is necessary for combustion are high-load operating ranges. The amount of injected water per working cycle is preferably chosen so small that there is no negative effect on the combustion process, the injection thus runs torque neutral. If appropriate, the parameters of the combustion (fuel quantity, ignition point, air quantity) for this purpose are preferably adapted to the injected water quantity.

The dependent claims show preferred developments of the invention.

The detection and / or determination device may preferably be a pressure sensor comprise, which is arranged on the water injector and / or the other water-carrying component of the water injection device and / or in a line region between the conveying element and the water injector. Thus, the pressure prevailing in these areas of the water injection device pressure can be detected and also allows the detection and / or determination of a Kühlungsnotwendigkeit. In particular, the detected pressure is compared with a pressure threshold. If the detected pressure is greater than the pressure threshold, it is concluded that the pressure or the temperature at the water injector and / or the other water-carrying component of the water injection device and / or in the line region between the conveying element and the water injector has risen so that a cooling necessary is. In this case, the pressure threshold corresponds to a predetermined pressure value at which no vapor formation occurs or is to be expected. Thus, the pressure threshold is chosen such that the pressure threshold is less than a pressure indicating a vapor formation.

Alternatively or additionally, the detection and / or determination device may comprise a temperature sensor which is arranged on the water injector and / or the other water-conducting component of the water injection device and / or in a line region between the conveyor element and the water injector. Thus, the temperature prevailing in these areas of the water injection device temperature can be detected. In particular, the detected temperature is compared with a temperature threshold. If the detected temperature is greater than the temperature threshold, it is concluded that the temperature at the water injector and / or the other water-bearing component of the water injection device and / or in the line region between the conveyor element and the water injector has risen so that cooling is necessary. In this case, the temperature threshold preferably corresponds to a predetermined temperature value at which no vapor formation occurs or is to be expected. Thus, the temperature threshold is selected such that the temperature threshold is less than a temperature from which steam is generated or vapor formation in the water injection device 1 is expected.

Another alternative for determining the need for cooling is to use a combined pressure and temperature sensor.

Alternatively or additionally, the detection and / or determination device is set up to determine the need for cooling the water injector and / or the other water-carrying component of the water injection device based on a calculation model.

In this case, advantageously, the calculation model can be constructed so that a water injection takes place at predetermined time intervals. The predetermined time intervals correspond to time intervals, after which it is expected that the temperature at the water injector and / or at the other water-bearing component of the water injection device and / or in a line region between the conveyor element and the water injector has increased so that cooling is necessary.

According to a particularly preferred embodiment of the invention, the calculation model is set up to calculate an estimated temperature and / or pressure at the water injector and / or at the other water-bearing component of the water injection device and / or in the line region between the conveyor element and the water injector. For this purpose, parameters can be taken into account which have an influence on the temperature or the thermal state of the water injection device, in particular the vehicle speed, the engine speed of the internal combustion engine, the temperature of the internal combustion engine, the ambient temperature and the position of the water injector and / or the other water-carrying component in relation to the internal combustion engine. In this case, the calculation model preferably corresponds to a heat transfer model.

Further preferably, the amount of water in the water injection can be chosen so that the amount of water is between 5% and 20% of the injected amount of fuel. As a result, the amount of water is chosen on the one hand so small that the injected water in this operating range or operating point of the internal combustion engine has no negative impact on the smoothness, torque and wear (water entry in engine oil). On the other hand, therefore, the amount of water is chosen so large that a cooling effect in the water injector and / or in the other water-bearing component of the water injection device is achieved.

According to a particularly preferred embodiment of the invention, the water injection device comprises a plurality of water injectors. In this case, the control unit is set up to control the water injectors for injecting water cyclically, if the result of the determination by the detection and / or determination device is positive. "Cyclic" means that the water injectors in the row are activated one after the other. Due to the non-simultaneous control of the water injectors can be ensured that the entire amount of injected water is evenly distributed to the cylinder and thus the combustion is not greatly affected. Further is For example, when the operating requirements change, for example, when the engine rapidly shifts to a higher load operating point, it is possible to promptly provide combustion-relevant water injection.

Particularly preferably, a distributor or rail is provided, on which the water injectors are arranged. In this case, the detection and / or determination device, in particular the pressure sensor and / or the temperature sensor, can be arranged on the distributor or rail.

It is also possible that the detection and / or determination device has a plurality of pressure sensors and / or temperature sensors, wherein a pressure sensor and / or a temperature sensor are assigned to each water injector. Thus, a more accurate determination of the need for cooling is made possible with each water injector. However, it is expected that the water injectors will have almost the same temperature due to their close proximity to each other so that a need for cooling for each water injector will be determined at the same or almost the same time.

More preferably, the invention relates to an internal combustion engine comprising a water injection device described above.

Another aspect of the invention relates to a method of operating a water injection device comprising a conveying element for conveying the water, and a water injector for injecting water, which is connected to the conveying element. The method preferably includes the step of detecting and / or determining a need for cooling the water injector and / or another water-bearing component of the water injector from vapor formation outside of engine operating ranges where combustion-related water injection is necessary. Further, the method includes the step of injecting water via the water injector when a result of detecting and / or determining the need for cooling is positive.

The advantages and explanations mentioned with reference to the described water injection device also apply to the method for operating the water injection device.

Preferably, the detection and / or the determination of the need for cooling, in which a pressure and / or a temperature at the water injector and / or at the other water-bearing component of the water injection device and / or in a line region between the conveying element and the water injector are detected. Thus, the need for cooling may be requested via a temperature measured in the water injector and / or a pressure measured in the water injector.

Alternatively or additionally, the need for cooling may be determined based on a calculation model. By using a calculation model, the detection and / or the determination of the need for cooling are ensured even in the event of failure of the temperature sensor and / or pressure sensor.

More preferably, the water injection device comprises a plurality of water injectors, wherein the water injectors of the plurality of water injectors for injecting water are cyclically driven when a result of detecting and / or determining the need for cooling is positive.

list of figures

• 1 eine stark vereinfachte schematische Ansicht einer Brennkraftmaschine mit einer Wassereinspritzvorrichtung gemäß dem bevorzugten Ausführungsbeispiel der vorliegenden Erfindung, und
• 2 eine vereinfachte schematische Ansicht der Wassereinspritzvorrichtung gemäß dem bevorzugten Ausführungsbeispiel.

Hereinafter, a preferred embodiment of the invention will be described in detail with reference to the accompanying drawings. In the drawing is:

• 1 a highly simplified schematic view of an internal combustion engine with a water injection device according to the preferred embodiment of the present invention, and
• 2 a simplified schematic view of the water injection device according to the preferred embodiment.

Preferred embodiment of the invention

The following is with reference to the 1 and 2 a water injection device 1 an internal combustion engine 2 according to a preferred embodiment of the present invention described in detail. In particular, the internal combustion engine 2 operated according to the Otto principle and with gasoline direct injection.

In 1 is the internal combustion engine 2 schematically illustrated, which has a plurality of cylinders, and a part of the water injection device according to the invention 1 , The internal combustion engine 2 includes one cylinder per cylinder 20 in which a piston 21 is movable back and forth. Further, preferably, the internal combustion engine 2 two intake valves per cylinder 25 each with an inlet channel 22 on, via which air to the combustion chamber 20 is supplied. Exhaust gas is via an exhaust duct 23 dissipated. This is the exhaust duct 23 one outlet valve 26 arranged. The reference number 24 further denotes a fuel injection valve.

At every inlet channel 22 is also a water injector 6 arranged, which via a control unit 10 Water in the inlet channel 22 the internal combustion engine 2 injects. In this embodiment, two water injectors 6 per cylinder provided, which leads to better treatment or to increase the maximum amount of water per combustion cycle injectable. Alternatively, a water injector per cylinder may be arranged.

In 2 is the water injection device according to the invention 1 shown in detail. The water injection device 1 comprises a conveying element designed in the form of a pump 3 and an electric drive 4 for driving the conveying element 3 ,

Furthermore, there is a water tank 5 provided, which by a first line 7 with the conveyor element 3 connected is. A second line 8th connects the conveyor element 3 with a distributor 9 or a rail to which a plurality of water injectors 6 connected. The second line 8th with the distributor 9 corresponds to the line area between the conveyor element 3 and the water injectors 6 ,

For injecting water into the inlet channels 22 the internal combustion engine 2 gets water from the water tank 5 through the conveyor element 3 into the water injectors 6 promoted.

Further, a water level and / or temperature sensor 18 for that in the water tank 5 provided water.

The water injection device 1 further comprises a recognition and / or determination device 14 for determining a need for cooling the water injectors 6 in an operating range outside engine operating ranges where combustion-related water injection is necessary and before steam is generated.

In other words, the operating range in which, according to the present invention, a need for cooling is determined is an operating range where combustion-relevant water injection is not necessary, e.g. at partial load (less than 50% of full load).

"Combustion-relevant" or "combustion-related" means that a water injection is needed to improve the quality of a combustion. These preferably include the prevention of knocking or knocking, the reduction of exhaust gas temperatures and the reduction of fuel consumption.

The operating areas in which a combustion-relevant water injection is necessary, preferably correspond to operating areas in which the internal combustion engine is operated at high load or full load.

The recognition and / or determination device 14 preferably also serves a need for cooling of the conveyor element 3 the water injection device 1 in the above operating range.

Furthermore, the water injection device 1 a control unit 10 on which is set up, the water injectors 6 to trigger for the injection of water, if a result of the determination by the detection and / or determination means 14 is positive.

In addition, the control unit 10 set up, the water level and / or temperature sensor 18 , the electric drive 4 and the recognition and / or determination device 14 head for.

The detection and / or determination device preferably comprises 14 a pressure sensor 15 and a temperature sensor 16 ,

The pressure sensor 15 and the temperature sensor 16 are preferably in the second conduit 8th between the conveyor element 3 and the water injectors 6 arranged. Alternatively, the sensors 15 . 16 at the distributor 9 be positioned.

Through the pressure sensor 15 and the temperature sensor 16 can the pressure and the temperature in the second line 8th be recorded.

The temperature in the second line 8th is due to the close arrangement of the water injectors 6 approximately equal to the temperature at the water injectors 6 so that it can be decided based on whether cooling the water injectors 6 is required.

Accordingly, based on the detected pressure in the second conduit 8th be determined, whether cooling the water injectors 6 and / or the second line 8th necessary is. Although in this embodiment only one pressure sensor 15 and a temperature sensor 16 are also conceivable that to each water injector 6 a pressure sensor and / or a temperature sensor are assigned.

As an additional option or in case of failure of the pressure sensor 15 and / or the temperature sensor 16 a determination of the need for cooling is the detection and / or determination device 14 advantageously arranged to determine a decision based on a calculation model.

For this purpose, the recognition and / or determination device preferably comprises 14 a memory 11 in which the calculation model is stored. In particular, the memory 11 Part of the control device 10 , However, the memory can 11 be formed as a separate component.

Particularly preferred is the control unit 10 set up the water injectors 6 to trigger cyclically for the injection of water, if the result of the determination by the detection and / or determination device 14 is positive.

In this case, furthermore, the amount of water injected for cooling the water-conducting components in the case of water injection preferably lies in a range between 5% and 20% of the injected fuel quantity.

The following will describe the method of operating the water injection device 1 explained in more detail.

According to the present invention, when driving in operating areas outside operating areas where water injection must take place due to combustion, there is a need for cooling the water injector 1 certainly.

As a result, in the operating areas where combustion-relevant water injection is not necessary, water still flows through the water injectors 6 injected.

Preferably, the water injectors 6 cyclically, for example, one after the other, driven to inject water. Thus, besides the cooling of the water injection device 1 ensure that the total amount of injected water, the current combustion, which would otherwise require no water injection in this operating range of the internal combustion engine, will not affect, or at least not significantly.

For the same purpose, preferably the amount of water passing through each water injector 6 is injected, a value between X% and Y% of an amount of water in a combustion-related water injection.

By alternating control of the water injectors 6 and the targeted adjustment of the amount of water to be injected is also made possible that with a rapid change in the operating range, such as rapid load jumps, a combustion-relevant water injection can take place immediately.

The determination of the need for cooling preferably takes place by detecting a temperature and / or a pressure in the second line 8th via the temperature sensor 16 and / or pressure sensor 15 ,

If the detected temperature is greater than a predetermined temperature threshold and / or the detected pressure is greater than a predetermined pressure threshold, it can be concluded that cooling is necessary.

The decision as to whether cooling is necessary can preferably be additionally made by means of a calculation model. By the calculation model is advantageously an estimated temperature in the second line 8th certainly. If the estimated temperature is greater than the predetermined temperature threshold, the need for cooling is determined. This is particularly advantageous in case of failure of the temperature sensor 16 and / or pressure sensor 15 ,

The amount of water to be injected may further preferably based on data of the water level and / or temperature sensor 18 be adjusted. For example, the amount of water to be injected by each water injector 6 be reduced when through the water level and / or temperature sensor 18 it is determined that the water level is less than a predetermined water level threshold and / or the temperature of the water tank 5 water is greater than a water tank temperature threshold.

The inventive water injection device and the method according to the invention for operating the water injection device reduce the high temperatures in the water injection device 1 , especially in the water injectors 6 that can be caused by the waste heat of the internal combustion engine of the internal combustion engine. Thus, the wear of the water injectors 6 and the other water-bearing components of the water injection device 1 be reduced.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2014/080266 A1 [0002]

Claims (10)

Water injection device (1) of an internal combustion engine, comprising: - A water tank (5) for storing water; - A conveying element (3) for conveying the water; - At least one water injector (6) for injecting water, which is connected to the conveying element (3); - A detection and / or determination device (14) for determining a need for cooling of the water injector (6) and / or another water-bearing component of the water injection device (1) from vapor formation outside of operating ranges of the internal combustion engine (2), in which a combustion-related Water injection is necessary, and - A control unit (10) which is adapted to control the water injector (6) for injecting water, when a result of the determination by the detection and / or determination means (14) is positive. Water injector after Claim 1 , characterized in that the detection and / or determination device (14) comprises a pressure sensor (15) and / or a temperature sensor (16), wherein the pressure sensor (15) and / or the temperature sensor (16) on the water injector (6) and or on the other water-carrying component of the water injection device (1) and / or in a line region (8) between the conveying element (3) and the water injector (6) are arranged. Water injection device according to one of the preceding claims, characterized in that the detection and / or determination device (14) is arranged to determine the need for cooling the water injector (6) and / or a component of the water injection device (1) based on a calculation model. Water injection device according to one of the preceding claims, characterized in that an amount of water in the water injection for cooling the water-carrying components is between 5% and 20% of the injected fuel quantity. Water injection device according to one of the preceding claims, characterized by a plurality of water injectors (6), wherein the control unit is arranged to cyclically control the water injectors (6) of the plurality of water injectors (6) for injecting water, if the result of the determination by the detection - and / or determination device (14) is positive. Internal combustion engine (2) comprising a water injection device (1) according to one of the preceding claims. Method for operating a water injection device (1) of an internal combustion engine (2), comprising a conveying element (3) for conveying water, and a water injector (6) for injecting water, which is connected to the conveying element (3), the steps of Method include: Detecting and / or determining a need for cooling the water injector (6) and / or another water-bearing component of the water injection device (1) from vapor formation outside operating ranges of the internal combustion engine in which combustion-related water injection is necessary, and - Injecting water through the water injector (6) when a result of detecting and / or determining the need for cooling is positive. Method according to Claim 7 , characterized in that a pressure and / or a temperature at the water injector (6) and / or at the other water-carrying component of the water injection device (1) and / or in a line region (8) between the conveying element (3) and the water injector (6 ). Method according to one of Claims 7 or 8th , characterized in that the need for cooling is determined based on a calculation model. Method according to one of Claims 7 to 9 characterized in that the water injection device comprises a plurality of water injectors (6), the water injectors (6) of the plurality of water injectors (6) being cyclically driven to inject water, if a result of detecting and / or determining the need for cooling is positive.

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