WO2018127316A1

WO2018127316A1 - Water injection device

Info

Publication number: WO2018127316A1
Application number: PCT/EP2017/078318
Authority: WO
Inventors: Ingmar Burak; Peter Schenk
Original assignee: Robert Bosch Gmbh
Priority date: 2017-01-04
Filing date: 2017-11-06
Publication date: 2018-07-12
Also published as: DE102017200045A1

Abstract

The present invention relates to a water injection device of an internal combustion engine comprising a water tank (5) for storing water, a conveying element (3) for conveying water, and at least one water injector (6) for injecting water, said water injector being connected to the conveying element (3). The conveying element (3) can be operated in a first operating direction (B1) to convey water to the water injector (6), and can be operated in a second operating direction (B2) to convey water from the water injector (6) to the water tank (5). The conveying element (3) comprises a rotating positive displacement pump. The invention also relates to an internal combustion engine comprising a water injection device of this kind, and a method for operating a water injection device of this kind.

Description

description

title

Water injection device prior art

The present invention relates to a water injection device of a

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 by knocking tilt and high exhaust gas temperatures is limited. 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, e.g. from WO 2014/080266 A1 discloses 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 pressure control.

A problem with known water injection systems is one possible

Icing of water-bearing components of the water injection system. To keep the system at temperatures below the freezing point of the

Could operate water injection system used water

For example, antifreeze components the water of the

Water injection system can be added. However, these components affect the combustion behavior of the internal combustion engine and require additional

Supplies. Disclosure of the invention

The water injection device according to the invention an internal combustion engine with the features of claim 1 has the advantage that damage to the water-bearing components of the water injection device, in particular the water injectors can be avoided by icing, without the components are designed ice pressure resistant. Neither additional components nor the combined use of a frost protection component and a fuel are required. This is inventively by a

A water injection device of an internal combustion engine comprising a water tank for storing water, a feed element for conveying water, and at least one water injector for injecting water connected to the feed element. The feed element is operable in a first operating direction to convey water to the water injector , Furthermore, the conveyor element is operable in a second operating direction to convey water from the water injector and / or other water-carrying components to the water tank. The Fürderelement preferably comprises a rotary positive displacement pump. In this case, the first operating direction of the conveying element corresponds to a first direction of rotation of the rotating positive displacement pump and the second operating direction of the conveying element corresponds to a second direction of rotation of the rotating positive displacement pump. When using a rotary positive displacement pump can be changed by the simple reversal of the direction of rotation, the water flow direction, that is, there is no need for a second conveyor element or a second pump and / or a changeover valve. Thus, at least a subset of water can be removed from the water injector and / or the other water-bearing components of the water injection device, so that even with icing the water injector and / or the other water-carrying components are not damaged.

The dependent claims show preferred developments of the invention.

Preferably, the positive displacement pump is designed as a gear pump. A gear pump offers the advantage of a uniform delivery of the medium to be pumped. Alternatively, the positive displacement pump as

Vietzellenpumpe, "gerotor" pump, internal gear pump, screw pump,

Roots blower, rotary piston pump, scroll pump, flywheel pump,

Barrier pump, or liquid ring pump may be formed. A Any combination of these types of pumps is also possible within the scope of the invention.

Further preferably, the positive displacement pump is arranged in the water tank or outside the water tank. By positioning the positive displacement pump in the

Water tank is achieved a space-saving arrangement. If the

Positive displacement pump is located outside of the water tank, easy access to the positive displacement pump, for example for maintenance, possible. In addition, the provision of the positive displacement pump outside of the water tank is gentle on the positive displacement pump in the event of icing in the water tank, with a eisdruckfeste configuration of the positive displacement pump is not needed.

The positive displacement pump is further preferably configured to suck in air. The positive displacement pump is advantageously self-priming. So can the

Positive displacement pump without further concerns outside the water tank. The positive displacement pump can also be started with a water injection device that is not or only partially filled with water. Furthermore, the positive displacement pump is preferably designed such that the

Positive displacement pump in the second direction of operation is tarnish. Thus, even in the displacement pump itself located water from the

Displacement pump are removed, whereby the positive displacement pump is protected against icing. Thus, damage to the positive displacement pump at low temperatures, e.g. less than 0 ° C at ambient conditions.

Further preferably, the positive displacement pump is designed such that the positive displacement pump is freeze-filled. This means that the

Positive displacement pump is designed such that their nature after a

Freezing is not affected. In this case, preferably the

Material properties of the positive displacement pump, in particular the

Young's modulus, the strength and the yield strength, chosen so that the positive displacement pump can withstand the volumetric expansion of the water and / or the ice pressure in the event of icing. Another aspect of the present invention relates to an internal combustion engine comprising a water injection device as described above.

The present invention further relates to a method of operating a Wasseremspritzvorricrttung an internal combustion engine, wherein the

Water injection device comprises a water tank for storing water, a conveying element for conveying water, and at least one water injector for injecting water, which is connected to the conveying element, wherein the conveying element is operable in a first operating direction to convey water to the water injector. The method includes the step of operating the conveyor element in a second operating direction to convey water from the water injector to the water tank, the conveyor element comprising a rotary positive displacement pump. The advantages mentioned with reference to the already described water injection device are also given here.

The operation of the positive displacement pump in the second operating direction is preferably carried out after switching off the internal combustion engine. This is particularly advantageous because after switching off the internal combustion engine no

(incineration-relevant) water injection takes place, which would otherwise stop the water in the water injection. This could be at low temperatures below freezing point of the water

Damage to the components of the water injection device, in particular the water injector, cause due to icing.

In the second operating direction, the positive displacement pump is preferably sucked empty of water, wherein the positive displacement pump is arranged to suck in air. In the first operating direction sucks advantageously emptied

Positive displacement pump first air, after which the positive displacement pump is filled with water. Thus, a filling of the water injection device takes place, even if there is air in the water injection device. Furthermore, it can be ensured that the air in the water injection device is removed during the filling of the water injection device. Thereby, potential cavitations in the components of the water injection device can be eliminated. Short description of the drawing

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

Drawing is a simplified schematic view of a

Internal combustion engine with a water injection device according to the preferred embodiment of the present invention, and a simplified schematic view of the water injection device according to the preferred

Embodiment in a first mode of operation, and a simplified schematic view of the water injection device according to the preferred

Embodiment in a second mode of operation.

Preferred embodiment of the invention

Hereinafter, with reference to Figures 1 to 3 a

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

In Figure 1, the internal combustion engine 2 is shown schematically, which has a plurality of cylinders, and a part of the invention

Water injection device 1. The internal combustion engine 2 comprises per cylinder a combustion chamber 20, in which a piston 21 is movable back and forth. Furthermore, the internal combustion engine 2 preferably has two inlet valves 25 per cylinder, each with an inlet channel 22, via which air is supplied to the combustion chamber 20. Exhaust gas is removed via an exhaust duct 23. This is on

Exhaust duct 23 an outlet valve 26 is arranged. The reference numeral 24 also designates a Kraftstoffeinspritzverrtil. At each inlet channel 22, a water injector 6 is further arranged, which via a control unit 10 water in the inlet channel 22 of the

Internal combustion engine 2 injects. In this embodiment, two water injectors 6 per cylinder are provided, which can be injected for better treatment or to increase the maximum per combustion cycle

Amount of water leads. Alternatively, a water injector per cylinder may be arranged.

FIG. 2 shows in detail the water injection device 1 according to the invention. The water injection device 1 comprises a rotating one

Positive displacement pump formed conveying element 3 and an electric drive 4 for driving the conveying element 3. Furthermore, a water tank 5 is provided, which through a first line

7 is connected to the conveying element 3. A second line 8 connects the conveying element 3 with a distributor 9 or a rail, to which a plurality of water injectors 6 is connected. The number of water injectors may vary depending on the design of the engine and requirements of the

Combustion vary.

The rotary positive displacement pump is operable in a first operating direction B1 to the water in a first conveying direction X1 to the

To promote water injectors 6. Furthermore, the rotary positive displacement pump in a second operating direction B2 is operable to water in a second

Promote conveying direction from the water injectors to the water tank 5. Thus, at least a subset of water may be removed from the water injectors and / or from the second conduit 8. This has the advantage that damage to the water injectors and / or the second line 8 can be avoided by icing.

The rotary displacement pump is particularly preferably designed as a gear pump. However, other types of rotary positive displacement pumps are also conceivable within the scope of the invention.

The rotary displacement pump is in this embodiment in

advantageously arranged outside of the water tank 5. In addition, preferably, the rotating positive displacement pump is arranged to suck in air or the rotary positive displacement pump is self-priming.

The positive displacement pump is furthermore preferably configured such that the positive displacement pump is emptyable in the second operating direction B2.

FIG. 2 shows the water injection device 1 according to the invention in a first operating mode or in normal operation. A normal operation is understood to mean the operation in which water is supplied from the water tank 5 to the water injectors 6 in the first forking direction X1, so that the water is injected into the intake passages 22 of the engine 2. As already mentioned, the first conveying direction X1 corresponds to the first one

Operating direction B1 of the conveying element. 3

If now via the control unit 10, which is preferably designed as the control unit of the internal combustion engine 2, a water injection under normal ambient temperatures requested so by means of the conveying element 3 water is sucked from the water tank 5. The rotating positive displacement pump is operated in the first operating direction B1 or in the first

Rotated direction of rotation For the sake of completeness, the second operating direction B2 of the positive displacement pump is also shown in dashed line in FIG.

However, if the water injection device 1 at temperatures below the freezing point of the water when driving or parking the

Internal combustion engine is deactivated, it may be due to in the

Water injection device 1 standing water lead to icing of water-bearing components and in particular the water injectors 6.

In order to avoid such icing, the water, which is located in the water injectors 6 in particular in Abstellfall the internal combustion engine 2, sucked from the water injectors 6 (Figure 3). For this purpose, the drive 4 of the conveying element 3 is controlled via the control unit 10 to change the operating direction of the conveying element 3, so that the water in a second

Delivery direction X2 through the second line 8 and the first line 7 to the water tank 5 is supplied. The rotary positive displacement pump in the operated second operating direction B2 or rotated in the second direction of rotation. The water injection device is operated here in a second operating mode. Analogously to FIG. 2, the sake of completeness in FIG. 3 is the first one

Operating direction B1 drawn with dashed line.

In the second operating direction B2, preferably the positive-displacement pump is sucked empty by the water, the positive-displacement pump sucking in the air located in the second line 8, which is emptied of water

In a later filling of the water injection device 1 is the

Positive displacement pump operated again in the first operating direction B1, the positive displacement pump first sucks the air in the, emptied of water, the first line 7 located air.

By the water injection device 1 according to the invention are the

Water injectors 6 from freezing, in particular In Abstellfall the internal combustion engine 2, protected A fail-safe Funktionswelse the water injection device 1 and thus the internal combustion engine 2 is thereby ensured. Fem he can by using the rotating

Positive displacement pump of the present invention to other components, such as an additional pump can be omitted.

Claims

Claims 1. A water injection device of an internal combustion engine, comprising:

a water tank (5) for storing water,

- A conveying element (3) for the promotion of water;

- At least one water injector (6) for injecting water, which is connected to the Fürderelement (3);

- wherein the conveying element (3) in a first operating direction (B1) is operable to convey water to the water injector (6), and in a second operating direction (B2) is operable to remove water from the water injector (6) to the water tank (5 ) to promote,

- Wherein the conveying element (3) comprises a rotary positive displacement pump.

2. Water injection device according to claim 1, characterized in that the positive displacement pump is designed as a gear pump.

3. Water injection device according to one of the preceding claims, characterized in that the displacement pump in the water tank (5) or outside of the water tank (5) is arranged

4. Water injection device according to one of the preceding claims, characterized in that the positive displacement pump is arranged to suck in air.

5. Water injection device according to one of the preceding claims,

characterized in that the positive displacement pump is designed such that the positive displacement pump in the second operating direction (B2) is emptied

6. Internal combustion engine, comprising a water injection device according to one of claims 1 to 5.

A method of operating a water injection device (1) of an internal combustion engine (2), wherein the water injection device (2) comprises a water tank (5) for storing water, a feeder element (3) for conveying water, and at least one water injector (6) Injecting water which is connected to the conveying element (3), wherein the conveying element (3) is operable in a first operating direction (B1) to convey water to the water injector (6), the method comprising:

- Operating the conveying element (3) in a second operating direction (B2) to promote water from the water injector (6) to the water tank (5), wherein the conveying element (3) comprises a rotary positive displacement pump

8. The method according to claim 7, characterized in that the operation of the positive displacement pump in the second operating direction (B2) after switching off the internal combustion engine (2)

9. The method according to claim 8, characterized in that in the second operating direction (B2), the positive displacement pump is emptied of water, wherein the positive displacement pump is arranged to suck in air.

10. The method according to claim 9, characterized in that in the first operating direction (B1), the emptied positive displacement pump first sucks air and then filled with water.