WO2018233992A1

WO2018233992A1 - Water injection device of an internal combustion engine

Info

Publication number: WO2018233992A1
Application number: PCT/EP2018/064130
Authority: WO
Inventors: Pascal Gladel; Ingmar Burak; Peter Schenk
Original assignee: Robert Bosch Gmbh
Priority date: 2017-06-22
Filing date: 2018-05-30
Publication date: 2018-12-27
Also published as: KR20200018474A; CN110785554A; EP3642469A1; BR112019027222A2; DE102017210487A1

Abstract

The invention relates to a water injection device for an internal combustion engine (2), comprising a water tank (5) for storing water, at least one water injector (6) for injecting the water into the internal combustion engine (2), at least one conveying element (3) for conveying water from the water tank (5) into the water injector (6). According to the invention, the water injection device (1) also comprises a shut-off element (11) which is arranged between the water tank (5) and the conveying element (3) and which is designed to maintain a system pressure at a level between the shut-off element (11) and the water injector (6) in order to prevent the water evaporating between the water tank (5) and the conveying element (3).

Description

description

title

Water injection device of an internal combustion engine

The present invention relates to a water injection device of a

Internal combustion engine and such an internal combustion engine.

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

Knock tendency and high exhaust gas temperatures is limited. One 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

DE 10 2015 208 476 A1 discloses a water injection system for an internal combustion engine.

In water injection systems for internal combustion engines, a water tank is normally provided so that at any time water for injection into the intake manifold or the

Combustion chamber of the internal combustion engine is available. In addition, in such water injection systems, water can be obtained by means of a water extraction plant

For example, be obtained from the exhaust system of the internal combustion engine in the motor vehicle or from the environment of the motor vehicle and, for example, also supplied to the water tank. From the water tank, for example, water can be conveyed by means of a pump via a distributor device to injection valves, through which the water is then injected, for example, into a suction pipe or a combustion chamber of the internal combustion engine. For this purpose, as in fuel injection systems, the distributor device can be provided to store water and to distribute it to a plurality of injectors, through which the water can then be injected. 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 water injectors and the lines of the water injection system. Due to the high temperatures of the parts of the internal combustion engine near the

Water injection system can heat the stagnant water and eventually vaporize. 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 be built up only delayed by the steam. 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.

Disclosure of the invention

According to the invention, a water injection device of an internal combustion engine is proposed. The water injection device comprises a water tank for storing water, at least one water injector for injecting the water into the internal combustion engine, a conveying element for conveying water from the water tank into the water injector. According to the invention, the water injection device further comprises a shut-off element, which is arranged between the water tank and the conveying element, and which is set up, a system pressure between the

Keep shut-off and the water injector at a level to prevent evaporation of the water between the water tank and the conveyor element located water.

Advantages of the Invention Compared to the prior art, the water injection device has a

Internal combustion engine has the advantage that the shut-off can be closed when the area between shut-off and water injectors is filled with water. The closed shut-off element forms a closed region between the shut-off element and the water injectors. Thus, the system pressure in this area between shut-off and water injectors in inactive Phases of the water injection device can be kept above the vapor pressure of the water. Thus, a vapor formation of the water is avoided and ensures short pressure build-up times and a fast injection release. The holding of the system pressure can be supported, for example, by an additional pressure accumulator and / or by elastic elements in water injection device, which work as a pressure accumulator.

The shut-off element can also be advantageously opened when the vehicle is parked, so that the area between the shut-off element and the water injectors can be emptied of water by conveying the conveying element backwards, so that the water injectors and the lines are protected from damage by freezing and expanding water.

Since the shut-off element is arranged between the water tank and the conveying element, the conveying element can advantageously be protected from flooding by water by closing the shut-off element after emptying the area between the shut-off element and water injectors. The connection from the conveyor element to

Water tank can be advantageously interrupted by closing the shut-off, so that the conveying element can not be flooded by water from the water tank. As a result, for example, the pump can also be arranged below a height of the water level of the water in the water tank without the pump being flooded by water from the water tank. Thus, a greater degree of freedom in the

Vehicle integration allows. This is especially important in systems with a water tank and a conveyor element in the rear of the vehicle, since the space available in the vertical space is very limited.

Further advantageous embodiments and modifications of the invention are made possible by the features specified in the subclaims. According to an advantageous embodiment, it is provided that the

Shut-off is designed as a shut-off valve. The shut-off valve ensures that water is in the area between the shut-off valve and the water injector.

According to an advantageous embodiment, it is provided that the

Barrier is set, the system pressure between the shut-off and the water injector at a level greater than 3 x 10 ⁵ Pa, preferably greater than 5 x 10 ⁵ Pa, more preferably greater than 5 x 10 ⁵ Pa and less than 10 x 10 ⁵ Pa to keep. Thus, on the one hand, vapor formation in the region between the shut-off element and the water injector can be avoided and, on the other hand, wall wetting of the water at the inlet channel can be avoided when water is injected into an inlet channel of an internal combustion engine. During active water injection, the components of the water injection system are cooled by inflowing water from the tank. At high temperatures and standing medium water in the

Water injection system, however, the temperature rises until the formation of steam. This effect is exacerbated in altitude, for example when traveling uphill, due to the falling air pressure and the resulting lower boiling temperature. If the system pressure between the shut-off element and the water injector at a level greater than 3 × 10 ⁵ Pa, preferably greater than 5 × 10 ⁵ Pa and less than 10 × 10 ⁵ Pa, the effect of steam formation is counteracted and it can even with deactivated water injection steam formation be prevented, since then the boiling temperature of the water rises to up to 140 ° Celsius.

According to an advantageous embodiment, it is provided that the

Shut-off is set to be brought into an open position with active water injection, in particular by energization. The shut-off valve is

preferably designed as an electrically operated shut-off valve, which can be controlled by a control unit in a simple and accurate manner. With active water injection, the shut-off valve is energized and thus enables the

Water delivery from the water tank into the water injector. When deactivating the water injection, the shut-off valve is also de-energized and keeps the system pressure thus at a pressure level sufficient for that

warming water does not boil.

According to an advantageous embodiment, it is provided that the

Shut-off is set to be normally closed. That's how it works

Shut-off, for example, be closed by a restoring force, for example by a spring element. This results in the advantage that with deactivated water injection, the pressure in the area between the shut-off valve and the water injectors can be maintained. In operation with active water injection, the shut-off valve can then be energized and thereby opened to promote the To allow water from the water tank. When the vehicle is parked after emptying the area between the shut-off element and the water injectors, the shut-off element is normally closed and thus provides protection against flooding for the conveying element.

According to an advantageous embodiment, it is provided that an accumulator is provided between the conveying element and the water injector. Such a pressure accumulator can keep the system pressure through the closed

Advantageously support shut-off.

According to an advantageous embodiment, it is provided that the

Water Injector comprises a return line, wherein the return line is arranged to return water from a region between the conveying element and the water injector in the water tank. The return line serves as a bypass for water, can flow through the water from the area between the conveyor element and the water injectors on the conveyor element and the shut-off valve back into the water tank.

According to an advantageous embodiment, it is provided that in the

Return line is arranged a check valve. The check valve leaves the

Flow of water only in the direction of the area between the conveying element and the water injectors to the water tank. By designing the check valve, that is, for example, by the pressure required to open the check valve, advantageously, the system pressure between the shut-off valve and the water injectors can be set.

According to an advantageous embodiment, it is provided that the

Water injector comprises a plurality of water injectors, which are connected to a manifold, wherein the manifold between the shut-off element and the water injectors is arranged.

According to an advantageous embodiment, it is provided that the

Is set when a change in the operating direction of

Conveying element, in particular by energization, brought into the open position to become. Thus, by a simple control of the shut-off water can be fed back into the water tank.

Also advantageous is an internal combustion engine comprising a water injection device according to the invention for the injection of water. The advantages obtained in relation to the water injection device according to the invention are also obtained. Particularly preferably, the internal combustion engine is operated according to the Otto principle and with gasoline. As an internal combustion engine, which is operated according to the Otto principle, the internal combustion engine is to be understood, in which a combustion of gasoline or gasoline-air mixture takes place by means of spark ignition in the form of a spark plug. Since in such an internal combustion engine, the ignition by the spark ignition is precisely predetermined, which can be compared with respect to the inventive

Water injector described advantages are fully exploited. Due to the short pressure build-up times and the rapid injection release of the water injection device according to the invention a tendency to knock can be avoided even with rapid load jumps.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it

1 is a highly simplified schematic view of an internal combustion engine with a water injection device according to a first embodiment of the present invention,

2 is a simplified schematic view of the water injection device according to the first embodiment,

Fig. 3 is a simplified schematic view of the water injection device according to a second embodiment of the present invention.

Embodiments of the invention Hereinafter, with reference to Figures 1 and 2 a

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

1 shows schematically the internal combustion engine 2, which has a multiplicity of cylinders, as well as a part of the water injection device 1 according to the invention. 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 per cylinder has an inlet channel 22, via which air is supplied to the combustion chamber 20. Exhaust gas is removed via an exhaust duct 23. For this purpose, at the inlet channel 22 a

Inlet valve 25 and the exhaust passage 23, an outlet valve 26 is arranged. The

Reference numeral 24 denotes a fuel injection valve. At the inlet channel 22, a water injector 6 is further arranged, which via a

Control unit 10 injects water into the inlet channel 22 of the internal combustion engine 2. In this embodiment, a water injector 6 per cylinder is provided. Alternatively, two water injectors per cylinder can be arranged for better treatment or to increase the maximum amount of water injectable per combustion cycle.

Further, the water injection device 1, for example, as a pump

trained conveying element 3 and an electric drive 4 for driving the conveyor element 3 on. As can be seen from FIG. 1 and FIG. 2, a water tank 5 for storing water, which is connected to the conveying element 3 by a first line 7, is furthermore provided. A second line 8 connects the

Conveying element 3 with a manifold 9 and a rail to which a plurality of water injectors 6 is connected. Between the water tank 5 and the conveying element 3, a shut-off element 1 1 is arranged, which divides the first line 7 into a first line section 7a and a second line section 7b and is controlled by the control unit 10.

The shut-off element 1 1 is set up, a system pressure between the

Shut off 1 1 and the water injector 6 to maintain a level at which a Evaporation of water located between the water tank 5 and the conveying element 3 is not evaporated. The shut-off 1 1, for example, a shut-off valve 1 1 a, for example, be an electrically operated shut-off valve 1 1 a. The shut-off valve 1 1 a is for example a 2/2 way valve.

In particular, the shut-off element 1 1 is set up to maintain the system pressure in the region between the shut-off element 1 1 and the water injectors 6 at a level greater than 3 × 10 ⁵ Pa, preferably greater than 5 × 10 ⁵ Pa. To be optimal

To allow water injection and thus also optimal combustion, the shut-off valve 1 1 a is arranged so that the system pressure in the area between the shut-off 1 1 and the water injectors 6 is kept smaller than 10 x 10 ⁵ Pa.

In particular, the shut-off valve 11a is designed to be de-energized e.g. is closed by a closing force of a spring element 12. When disabled

Water injection, the shut-off valve 1 1 a is normally closed and holds the

System pressure thus on a level sufficient to avoid steam formation (first switching position of the shut-off valve 1 1 a). Upon activation of the

Water injection, the shut-off valve 1 1 a is energized and thus allows a promotion of the water from the water tank 5 to the water injectors 6 (second switching position of the shut-off valve 1 1 a).

The check valve 1 1 a is also set to be opened by energization when changing the operating direction of the conveyor element 3, so for example a change in the direction of rotation of the pump, water is fed back into the water tank 5 (second switching position of the check valve 1 1 a ).

The water injection device 1 comprises a plurality of water injectors 6. For this purpose, a distributor 9, for example a water rail, is provided in the water injection device 1, to which the plurality of water injectors 6 can be connected and which distributes the water to the water injectors 6.

In Figure 2, the check valve 1 1 a is in the first switching position, ie the closed position. By providing a shut-off element 1 1 between the water tank 5 and the conveying element 3, vapor formation in the water injection device 1 in the area between the shut-off element 1 1 and the conveying element 3 can be prevented. Thus, the water injection device 1 is operable at inactive operating points and can be brought into use quickly when the combustion of the

Internal combustion engine 2 requests a water injection.

In addition, the water injection device 1 in this embodiment, a pressure accumulator 14. Accumulator 14 is intended to compensate for pressure fluctuations and can assist in closed shut-off valve 1 1 maintain the system pressure in the area between shut-off 1 1 and 6 water injectors. For this purpose, the pressure accumulator 14 may be arranged, for example, between the conveying element 3 and the water injector 6. But it can also elastic components in the water injection device 1, for example, elastic parts of the manifold 9 act as a pressure accumulator 14.

The second embodiment of the water injection device 1 according to the invention of Figure 3 differs from the first embodiment in that in the second embodiment of the water injection device 1, a return line 15 is provided. Via the return line 15, water can flow back from a region between the conveying element 3 and the water injector 6 into the water tank 5. In this embodiment, a check valve 16 is disposed in the return line 15. The check valve 16 allows water from the area between the

Conveying element 3 and the water injector 6 coming back flow into the water tank 5 but blocked simultaneously in the other direction. The check valve 16 is

set up, de-energized by a pressure of water in the area between

Conveying element 3 and water injectors 6, which against against. a force of one

Spring element 13 acts to be opened (open position of the check valve 16). When the pressure in the area between the conveyor element 3 and water injectors 6 can no longer overcome the force of the spring element 13, the check valve 16 closes (closed position). In Figure 3, the check valve 16 is in the closed position.

Of course, other embodiments and hybrid forms of the illustrated embodiments are possible.

Claims

claims

1 . Water injection device of an internal combustion engine (2), comprising:

a water tank (5) for storing water,

- At least one water injector (6) for injecting the water in the

Internal combustion engine (2),

a conveying element (3) for conveying water from the water tank (5) into the water injector (6),

characterized in that the water injection device (1) further comprises a shut-off element (1 1), which between the water tank (5) and the

Conveying element (3) is arranged, and which is adapted to maintain a system pressure between the shut-off (1 1) and the water injector (6) at a level to evaporate the between the water tank (5) and the conveying element (3) located To avoid water.

2. Water injection device according to claim 1, characterized in that the shut-off element (1 1) as a shut-off valve (1 1 a) is formed.

3. Water injection device according to one of the preceding claims, characterized in that the shut-off (1 1) is set, the system pressure between the shut-off (1 1) and the water injector (6) at a level greater than 3 x10 ⁵ Pa, preferably greater than 5 x 10 ⁵ Pa and less than 10 x 10 ⁵ Pa, to hold.

4. Water injection device according to one of the preceding claims, characterized in that the shut-off element (1 1) is set, when active

Water injection, in particular by energization, to be brought into an open position.

5. Water injection device according to one of the preceding claims, characterized in that the shut-off element (1 1) is arranged to be normally closed.

6. Water injection device according to one of vorhergien claims, characterized

in that an accumulator (14) is provided between the conveying element (3) and the water injector (6).

7. Water injection device according to one of the preceding claims, characterized in that the water injection device (1) comprises a return line (15), wherein the return line (15) is arranged, water from an area between the conveying element (3) and the water injector (6). attributed to the water tank (5).

8. Water injection device according to claim 7, characterized in that in the return line (15) a check valve (16) is arranged.

9. Water injection device according to one of the preceding claims, characterized in that the water injection device (1) a plurality of

Water injectors (6), which are connected to a manifold (9), wherein the manifold (9) between the shut-off (1 1) and the water injectors (6) is arranged.

10. Water injection device according to one of the preceding claims, characterized in that the shut-off element (1 1) is adapted to be brought in a change in the operating direction of the conveying element (3), in particular by energization, in the open position.

1, an internal combustion engine, comprising a water injection device (1) for injecting water according to one of the preceding claims.