EP3292295A1

EP3292295A1 - Device for injecting water of an internal combustion engine and method for operating a device of this type

Info

Publication number: EP3292295A1
Application number: EP16717328.5A
Authority: EP
Inventors: Ingmar Burak; Peter Schenk
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-05-06
Filing date: 2016-04-13
Publication date: 2018-03-14
Also published as: CN107567539B; CN107567539A; WO2016177543A1

Abstract

The present invention relates to a device for injecting water into an internal combustion engine (2), comprising: a water tank (5) for storing water; a conveying element (3) for conveying the water, wherein the conveying element (3) is connected to the water tank (5); at least one water injector (6) for injecting water, which is connected with the conveying element (5); a drive (4) for driving the conveyor element (3); and a control unit (10) which is configured to detect a power consumption of the drive (4) in order to determine a system pressure in a line region (8) between the conveying element (3) and the water injector (6). A further aspect of the present invention relates to an internal combustion engine (2) comprising a device (1) according to the invention. The invention further relates to a method for operating a device (1) according to the invention.

Description

Description title

Device for injecting water of an internal combustion engine and

Method for operating such a device

State of the art

The present invention relates to a device for injecting water of an internal combustion engine and such an internal combustion engine. Another aspect of the invention relates to a method of operating such a 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 operated optimally 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, 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 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 during this time, 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 to vapor formation. This effect is exacerbated when driving at high altitude, where the air pressure is lower. The formation of steam prevents rapid pressure build-up when the pump is switched on again fast operational readiness of water injection. This can be too

Functional impairment when restarting the water injection system lead. Due to this delayed readiness for operation, temperature peaks in the exhaust gas as well as knocking events in the combustion could occur during rapid load jumps.

Disclosure of the invention

The inventive device for injecting water of a

Internal combustion engine with the features of claim 1 has the advantage over that the operational readiness of the water injection device can be determined quickly and inexpensively. This is inventively achieved by detecting a current consumption of a drive of the conveying element, since the current consumption is related to the torque of the electric drive of the conveying element and thus dependent on

System pressure of the water injection device is. Here, the

Inventive device for injecting water

Internal combustion engine, a water tank for storing water, a conveying element for conveying the water, wherein the conveying element is connected to the water tank, at least one water injector for injecting water, which is connected to the conveying element, a drive for driving the conveying element, and a control unit which is arranged to detect a current consumption of the drive in order to determine a system pressure in a line region between the conveying element and the water injector. By evaluating the current consumption of the drive, it is possible to indirectly draw conclusions about the system pressure. If no

Steam formation is detected, the requirement for faster

Ready for operation of the water injection are met. In the presence of steam formation, the release of the injection can take place at the earliest possible date and / or measures can be taken to prevent further vapor formation and to initiate a condensation of the vapor. Furthermore, in the invention according to the invention can be dispensed with an additional pressure sensor.

The dependent claims show preferred developments of the invention. Preferably, the drive is a DC motor or brushless

DC motor trained. As a DC motor or commutator is a rotating electric machine to understand, which is operated with DC. As a brushless DC motor is the engine to understand, which contrary to its naming not on the operating principle of a

DC machine is based, but how a three-phase synchronous machine with excitation by permanent magnets is constructed.

For determining the system pressure, the control unit may preferably be set up to provide a phase current of at least one coil of the brushless one

DC motor to capture. Particularly preferably, the control unit is set up, a phase current of all coils of the brushless

DC motor to capture. When the current consumption is equal to or greater than a first predefined

Is current value, the control unit is advantageously set up

To open water injector for injecting water. The first predefined current value may be pre-stored in the control unit and corresponds to the situation in which the delivery element has built up a pressure required to inject water.

More preferably, the control unit is configured to determine a vapor formation when the conveyor element is switched on when the current consumption of the drive is equal to or less than a second predefined current value. The second predefined current value can be pre-stored in the control unit and corresponds to the situation in which the conveying element due to

Water evaporation has not yet built up the required pressure.

In particular, the first predefined current value and the second predefined current value are the same.

If vapor formation is detected, the control unit is preferably set up to control combustion of the internal combustion engine so that further vapor formation is reduced in order to allow the fastest possible pressure build-up by the conveying element. Thus, in an advantageous manner, the control unit can be set up to operate the conveying element and the water injector in such a way that the steam in the line region between the conveying element and the water injector is removed by the water injector. Alternatively or additionally, the control unit may preferably be configured to carry out one or more targeted, non-combustion-relevant water injections. As a result, the temperature in the line region between the conveying element and the water injector can be reduced, which leads to a further development of steam ceasing.

The control unit may preferably have an external conveyor element control unit. Alternatively or additionally, a

Engine control unit serve as the control unit according to the invention.

Another aspect of the invention relates to an internal combustion engine comprising a device according to the invention for injecting water. Thus, the advantages described in relation to the device according to the invention are connected.

Particularly preferably, the internal combustion engine is set up to be operated with gasoline and according to the Otto principle. As such an internal combustion engine, the internal combustion engine is to be understood, in which combustion takes place by means of spark ignition in the form of a spark plug. In such a

Internal combustion engine, the ignition is exactly predetermined by the spark ignition. Thus, when requested water injection by the power consumption of the drive specific system pressure the

Water injection or the ignition timing can be selected so that an optimal combustion takes place. As a result, temperature peaks in the exhaust gas and knocking events in the combustion can be avoided.

Furthermore, the present invention relates to a method for operating a device for injecting water, which at least one

A water injector, a conveying element for conveying water and a drive for driving the conveying element, wherein a current consumption of the drive is detected to determine a system pressure in a line region between the conveying element and the water injector.

Preferably, a phase current of at least one coil of a brushless DC motor is detected to determine the system pressure. The water injector is opened according to the invention for injecting water when the current consumption is equal to or greater than a first predefined

Current value is.

More preferably, when the conveyor element is switched on, vapor formation is determined when the current consumption of the drive is equal to or less than a second predefined current value.

Advantageously, a combustion of the internal combustion engine is controlled so that a further formation of steam is reduced to a

To allow the fastest possible pressure build-up by the conveyor element.

Brief description of the drawings

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

Figure 1 is a greatly simplified schematic view of a

Internal combustion engine with a device for injecting water according to the preferred embodiment of the present invention,

Figure 2 is a simplified schematic view of the device for

Injecting water according to the preferred

Embodiment, and

Figure 3 is a diagram in which a time course of

Power consumption of the engine and a corresponding course of the pressure in a line region of the device according to the invention are shown.

Preferred embodiment of the invention

Hereinafter, referring to FIGS. 1 to 3, an apparatus 1 for injecting water of an internal combustion engine 2 according to a preferred embodiment of the present invention will be described in detail described. 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 having 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 fuel injection valve.

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.

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

Furthermore, a water tank 5 is provided, which is connected by a first line 7 with 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 second line 8 with the

Distributor 9 corresponds to the line area between the conveying element 3 and the water injectors 6.

For injecting water into the inlet channels 22 of the internal combustion engine 2, water from the water tank 5 through the conveyor element 3 in the

Promoted water injectors 6. For a condensate of an evaporator, not shown, an air conditioner is preferably used, including the Inventive device 1 for injection of water a supply line

1 1 has.

Alternatively or in addition to the condensate, deionized water can be conveyed into the water tank 5 via a refill line 12. In the refill line

12 can optionally be provided a sieve. Further, a pre-filter 16 in the first conduit 7 and a fine filter 17 in the second conduit 8 are arranged. The pre-filter 16 and the fine filter 17 are optionally heated. Further, a

Water level and / or temperature sensor 18 is provided for the water in the water tank 5, which is controllable via the control unit 10.

The control unit 10 is formed as an external conveyor element control unit. Alternatively or additionally, the control unit 10 a

Have engine control unit. Thus, the control of the drive 4 and the water injectors 6 by the conveyor element control unit and / or the engine control unit can be carried out.

In order to determine a system pressure in the second line 8 between the conveying element 3 and the water injectors 6, the control unit 10 is set up to detect a current consumption of the drive 4. In particular, the electric drive 4 is designed as a brushless DC motor with a plurality of coils. In this case, a phase current of the coils of the brushless DC motor is detected.

If the current consumption of the drive 4 is greater than or equal to a first predefined current value, it is recognized that there is no vapor formation in the second line 8. In such a case, the

Water injectors 6 are opened to inject water when a

Water injection for combustion e.g. through the

Internal combustion engine control unit is required.

If there is vapor formation in the second conduit 8, eg after long intermediate phases during which no water injection has taken place, this is recognized by the fact that the current consumption of the drive 4 is equal to or less than a second predefined current value. If in the meantime a combustion-relevant water injection is requested, the release of the injection takes place at the earliest possible time. To postpone this time in time, the combustion of the internal combustion engine 2 can be adjusted so that no further formation of steam in the second line 8 is formed. A possible

Measure is, for example, a reduction in the performance of

Internal combustion engine, whereby the temperature of the internal combustion engine can drop.

Alternatively or additionally, the control unit 10 may be configured to control the conveying element 3 and the water injectors 6 in order to control the flow in the

Line region 8 between the conveyor element 3 and the water injectors 6 existing steam to remove. Furthermore, one or more, for combustion not relevant, water injections take place, whereby the line region 8 between the conveyor element 3 and the water injectors 6 is cooled. Thus, a pressure build-up by the conveying element 3 can be made possible as quickly as possible.

3 shows a diagram in which a time course t in seconds, t (s), a detected system pressure P (Pa) in the second line 8 at the distributor 9 and a time profile of the current consumption l (A) of the drive 4 according to the preferred embodiment are shown.

The time profile of the current consumption, which has fluctuations, is denoted by the reference numeral 15 and the time profile of the detected system pressure by the reference numeral 16. Both parameters each have a first region I and a second region II. The x-axis denotes the time t in s and the y-axis the current I in A and the detected pressure P x 10 ⁵ in Pa.

Furthermore, an average value 15 'of the current of the drive 4 in the first region I and an average value 15 "of the current of the drive 4 in the second region II are shown in the diagram of FIG.

As can be seen from FIG. 3, the first region I designates the case in which vapor formation is present in the line region 8 between the conveying element 3 and the water injectors 6. On the other side the second region II the case in which in the second line 8 and the manifold 9 pressure is already built up by the conveying element 3.

When the pressure level in the second line 8 and the distributor 9 is in the second region I, in particular when the flow of the drive 4 is less than the mean value 15 'when the delivery element 3 and the closed water injectors 6 are switched on, it is recognized that the pressure due to the present Steam formation in the line region 8 between the conveyor element 3 and the water injectors 6 is built up delayed. In this regard, can

Measures are taken, by which further vapor formation can be reduced or eliminated. Thereafter, a combustion-related water injection may occur at an earliest possible time when the sensed current is greater than the average value 1 5 ". Instead of using the averages 15 'and 1 5", vapor formation in the water may occur

Line region 8 between the conveyor element 3 and the water injectors 6 are determined based on a maximum current value of the region I. When the detected current with the delivery element 3 and

closed water injectors 6 is smaller than the maximum current value of the region I, it can be concluded that steam has formed in the second line 8 and the distributor 9. On the other hand, when the detected current is larger than the maximum current value of the region I, a water injection required for the combustion can be quickly realized.

The mean values 1 5 'and 15 "and the maximum current value of the region I are pre-stored in the control unit.

The device 1 according to the invention for the injection of water offers the advantage of a quick exchange of their operational readiness and the release of the injection at the required system pressure. Furthermore, a delayed pressure buildup can be quickly detected when steaming. For this purpose, additional components, such as e.g. to be dispensed with a pressure sensor, resulting in a more cost-effective and compact design of the device 1 according to the invention.

Claims

Device for injecting water into an internal combustion engine (2), comprising:

- a water tank (5) for storing water;

- a conveying element (3) for conveying the water, which

Conveying element (3) with the water tank

(5) is connected,

- at least one water injector (6) for injecting water, which is connected to the conveying element (3),

- a drive (4) for driving the conveying element (3), and

- A control unit (10), which is set up to record a current consumption of the drive (4) in order to determine a system pressure in a

Line area (8) between the conveying element (3) and the

Determine water injector (6).

Device according to one of the preceding claims, wherein the drive (4) is designed as a direct current motor or brushless direct current motor.

Device according to claim 2, wherein the control unit (10) is set up to generate a phase current of at least one coil of the brushless

DC motor to determine the system pressure.

Device according to one of the preceding claims, wherein the control unit (10) is set up to open the water injector (6) to inject water when the current consumption is greater than or equal to a first predefined current value.

Device according to one of the preceding claims, wherein the control unit (10) is set up to determine steam formation when the

Current consumption of the drive (4) when the conveying element (3) is switched on and the water injector (6) is closed is equal to or less than a second predefined current value.

6. The device according to claim 5, wherein the control unit (10) is set up to control combustion of the internal combustion engine (2) in such a way that further steam formation is reduced in order to enable the fastest possible pressure build-up through the conveying element (3).

7. Internal combustion engine, which has a device (1) according to one of the

includes previous claims.

8. Internal combustion engine according to claim 7, which is set up to be operated with gasoline and according to the Otto principle.

9. Method for operating a device (1) for injecting

Water, which comprises at least one water injector (6), a conveying element (3) for conveying water and a drive (4) for driving the conveying element (3), wherein a current consumption of the drive (4) is detected in order to determine a system pressure in a To determine the line area (8) between the conveying element (3) and the water injector (6).

10. The method according to claim 9, wherein for determining the system pressure a phase current of at least one coil of a brushless

DC motor is detected.

1 1 . Apparatus according to claim 9 or 10, wherein the water injector (6) is opened to inject water when the current consumption is greater than or equal to a first predefined current value.