DE102015208480A1 - Water injection device of an internal combustion engine and method for operating such a water injection device - Google Patents

Abstract

The present invention relates to a water injection device of an internal combustion engine (2) having a water tank (5) for storing water, at least one water injector (6), a conveying element (3) for conveying the water, which via a suction line (7) and via a Return line (13) is connected to the water tank (3), and a first heating element (19 a) comprises, which is at least partially disposed on the suction line (7). According to the invention, the first heating element (19a) is arranged to thaw water which is frozen in the water tank (5) and / or in the suction line (7). Furthermore, the conveying element (3) according to the invention is adapted to convey the thawed water in the suction line (7) via the return line (13) back into the water tank (5). Another aspect of the invention relates to an internal combustion engine having a water injection device (1) according to the invention and to a method for operating the water injection device (1).

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.

One problem with known water injection systems is possible icing of water-bearing components of the water injection system. In order to operate the system even at temperatures below the freezing point of the water used in the water injection system, a heating element is used. A disadvantage of this heating element is that the heat is reduced to a small location around the heating element. This can result in a non-optimal thawing of the frozen components of the water injection system. In particular, when water is sucked due to a requested water injection from a partially thawed water tank, it may lead to a loss of contact of the heating element with the still frozen water. This is called "ice cave effect". This makes it possible that not enough water is available for further injection, which may cause an impairment of the operation of the internal combustion engine.

Disclosure of the invention

The water injection device of an internal combustion engine according to the invention with the features of claim 1 has the advantage over that thawing of icy components of the water injection device can be done safely and quickly. Furthermore, the so-called ice cave effect is avoided, which could otherwise lead to a significant reduction in the efficiency of the heating element. This is inventively achieved by a water injection device of an internal combustion engine, which comprises a water tank for storing water, at least one water injector, a conveying element for conveying the water, which is connected via a suction line and a return line to the water tank, and a first heating element, which at least partially disposed on the suction line. According to the invention, the first heating element is arranged to thaw water in the water tank and / or in the suction line, which is frozen, in order to convey the thawed water in the suction line via the return line back into the water tank. Due to the circulation of the thawed water, the heat generated by the heating element is distributed evenly in the water tank. Thus, a prior operational readiness of the water injection device at temperatures below the freezing point of the water and a safe thawing of the total amount of water of the water tank is made possible in a fast manner. As a result, the requirements for the first heating element can be reduced, resulting in a cost-effective and compact construction of the water injection device.

The dependent claims show preferred developments of the invention.

In order to assist the thawing of the frozen water, preferably, the water injection device further comprises a second heating element, which is at least partially disposed on the return line. The second heating element is arranged to additionally heat the water thawed by the first heating element. In addition, the second heating element can be turned on, even if water, which is located in the return line, is frozen. Thus, the water in the return line can be thawed by the waste heat of the second heating element in addition to the registered in already thawed water heat.

Further preferably, the water injection device comprises a delivery line, via which the delivery element is connected to the water injector, and on which a third heating element is at least partially arranged. The third heating element may act to assist the first heating element and / or the second heating element.

More preferably, the water injection device comprises a fourth heating element, which is arranged in the water tank. By providing the fourth heating element, a faster thawing of the iced water tank is achieved.

The first heating element and / or the second heating element and / or the third heating element and / or the fourth heating element may preferably be formed as a unit.

Particularly preferably, the first heating element and / or the second heating element and / or the third heating element and / or the fourth heating element to an electric heating element and / or a hydraulic heat exchanger. An electric heating element offers the advantage of easy control. On the other hand, a hydraulic heat exchanger can be adapted to the particular space and design requirements, resulting in optimum heat transfer to the frozen water.

The hydraulic heat exchanger is preferably arranged to use the cooling water of the internal combustion engine for thawing the frozen water. Thus, the heat contained in the cooling water by the cooling of the internal combustion engine can be reused.

Advantageously, the conveyor element is arranged to be operated in a non-optimal operating point of the conveyor element to generate heat. A non-optimal operating point is to be understood as the operating point at which a part of the electrical power in a drive of the conveying element is converted into heat.

When the conveyor element is designed as a pump, operation of the pump at a lower speed than that at an optimum operating point is desired, so that the generated heat of the conveyor element is transferred to the water.

The conveying element is furthermore preferably set up to be operated during an active water injection during the thawing process in such a way that a minimum amount of the thawed water remains in the water tank. Thus, the thawing of the remaining frozen water can be uninterrupted even if a large amount of water injection is required.

Another aspect of the present invention relates to an internal combustion engine comprising a water injection device according to the invention. The advantages obtained in relation to the water injection device according to the invention remain here as well.

In particular, 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 a combustion of gasoline or gasoline-air mixture takes place by spark ignition in the form of a spark plug. Since in such an internal combustion engine, the ignition timing is precisely predetermined by the spark ignition and the combustion is improved by the water injection, a fail-safe operation of the internal combustion engine is achieved by the circulation of the water thawed by the at least one intended heating element in the water injection device.

In particular, the water injection device according to the invention is used in an internal combustion engine with direct injection and turbocharging.

Furthermore, the present invention relates to a method for operating a water injection device with at least one water injector, and a conveying element for conveying the water, which is connected via a suction line and a return line to a water tank. According to the method according to the invention, water which is frozen in the water tank and / or in the suction line is thawed by a first heating element. The thawed water in the intake is conveyed according to the invention via the return line back into the water tank of the water injection device.

Preferably, the conveyor element is operated at a non-optimal operating point of the conveyor element to generate heat.

Preferably, the conveying element is operated during an active water injection during the thawing process so that a minimum amount of thawed water remains in the water tank.

Brief description of the drawings

Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein like or functionally identical parts are designated by the same reference numerals. In the drawing is:

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

3 a simplified schematic view of the water injection device according to a second embodiment,

4 a simplified schematic view of the water injection device according to a third embodiment, and

5 a simplified schematic view of the water injection device according to a fourth embodiment.

Embodiments 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 first 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 , which has a plurality of cylinders, as well as a part of the water injection device according to the invention 1 shown schematically. 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 an 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 pump element designed as a pumping element 3 and an electric drive 4 to drive the pump. Furthermore, there is a water tank 5 provided, which through a suction line 7 with the conveying element 3 connected is. A promotion line 8th connects the conveyor element 3 with a distributor 9 or a rail to which a plurality of water injectors 6 connected.

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 fed. For a condensate of an evaporator, not shown, an air conditioner is preferably used, including the water injection device according to the invention 1 a supply line 11 having.

Alternatively or in addition to the condensate, deionized water can be supplied via a refill line 12 in the water tank 5 be encouraged. In the refill line 12 Optionally, a sieve can be provided. Further, a pre-filter 16 in the first line 7 and a fine filter 17 in the promotion line 8th arranged, which can be optionally heated.

Will now via the control unit 10 , which is preferred as the control unit of the internal combustion engine 2 is designed to request a water injection under normal ambient temperatures, so by means of the conveying element 3 Water from the water tank 5 sucked. To set the desired system pressure in the manifold 9 is a pressure regulator 15 in the form of a shutter in a return line 13 arranged, which the delivery line 8th with the water tank 5 combines. According to an alternative embodiment of the invention, instead of a diaphragm, a check valve as the pressure regulator 15 to be used. For pressure control is also a pressure sensor 14 in the promotion line 8th intended.

If, however, the water injection device 1 at temperatures below the freezing point of the water of the water injection device 1 used, it can lead to icing of the water tank 5 and / or the suction line 7 to lead. This area of the water injection device 1 can be sensitive, even if the internal combustion engine 1 in operation, since this area is from the combustion chamber 22 can be removed. To icing the water tank 5 and / or the suction line 7 To recognize, for example, a temperature or level sensor 18 to be used.

To thaw the frozen water is a first heating element 19a in the intake pipe 7 arranged. The first heating element 19a is set up in the water tank 5 and / or in the suction line 7 thawed water which is frozen.

The conveying element 3 is further configured, the thawed water in the intake 7 and / or the water tank 5 via the return line 13 back to the water tank 5 to promote.

The first heating element 19a may be formed as an electrical heating element such as an electrical resistance and / or as a hydraulic heat exchanger. In this case, the hydraulic heat exchanger can be set up, cooling water of the internal combustion engine 2 to use to thaw the frozen water.

For as early as possible operational readiness of the water injection device 1 First, a small part of the water in the water tank 5 and / or in the suction line 7 of the conveyor element 3 thawed. Once this volume of water has thawed, the conveying element becomes 3 with still inactive water injection, ie with closed water injectors 6 , switched on. The thawed water is then returned via the return line 13 over the pressure regulator 15 to the water tank 5 fed.

There is thus a circulation of the thawed water, whereby the heat stuck in the water evenly in the water tank 5 is distributed. This may cause the deicing of the water tank 5 continue if it is not completely thawed. Thus, in the next circulation, a larger amount of water is available, which increases as the number of circulation operations increases. This results in a very fast thawing of the frozen water.

To enhance the effect of heating by circulation, the conveying element can 3 be operated in a non-optimal operating point. Preferably, the conveying element 3 be operated deliberately in a speed range in which the heat losses of the conveyor element 3 increase. That is, the efficiency of the conveyor element 3 at the non-optimal operating point is not maximum. This leads to further heating of the circulating water, which facilitates the thawing of the still frozen water.

Is due to the driving conditions during this optimized thawing a water injection by the internal combustion engine 2 requested, so first a water injection amount is allowed, so that enough thawed water is still in the partially iced water tank 5 remains. Thus, the thawing process can be carried out continuously.

If the allowable water injection amount is insufficient for the combustion relevant injection, that is, if the injection amount of water available is smaller than a minimum water injection amount needed for the combustion, the performance of the internal combustion engine becomes 2 reduced. Thus, problems in the operation of the internal combustion engine 2 , such as knocking, are avoided due to the reduced amount of water injection.

Once it is ensured that the water tank 5 remaining thawed amount of water is enough to continue the thawing process, even if that of the internal combustion engine 2 required water injection amount is injected, this water injection amount is actually released.

By the circulation of the through the first heating element 19a thawed water, the generated heat is optimally in the water tank 5 distributed. Thus, via the water injection device according to the invention 1 Thawing the frozen water in the water tank 5 as well as in the intake line 7 done faster. The water injection device 1 is thus ready earlier.

To assist the thawing of the frozen water, the water injection device can 1 according to a second embodiment ( 3 ) Further, a second heating element 19b exhibit. The second heating element 19b is on the return line 13 arranged. Thus, the already thawed water can be further heated during its circulation, to more heat in the water tank 5 initiate.

The second heating element 19b may also help if the return line 13 completely or partially frozen.

The 4 shows a third embodiment of the present invention. The third embodiment differs from the second embodiment basically in that a third heating element 19c in the promotion line 8th is arranged. Thus, more heat can be transferred to the thawed water. Preferably, the third heating element 19c in front of the return line 13 arranged in the conveying direction of the water.

Like from the 5 it can be seen, the water injection device 1 According to a fourth embodiment of the present invention, a fourth heating element 19d on.

The fourth heating element 19d is inside the water tank 5 arranged, on. By providing a fourth heating element, the frozen water in the water tank 5 thawed faster. Thus, the water injection device 1 be ready earlier.

It should be noted that the heating elements 19a . 19b . 19c and 19d can form a heating unit. Especially if the heating elements 19a . 19b . 19c and 19d are designed as hydraulic heat exchangers, the transfer of heat to the water can be done in a unitary cycle.

Furthermore, the heating elements 19a . 19b . 19c and 19d also as the heating of the heated filter elements 16 and 17 serve.

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 (14)

Water injection device of an internal combustion engine ( 2 ), comprising: - a water tank ( 5 ) for storing water, - at least one water injector ( 6 ), - a conveying element ( 3 ) for conveying the water, which via a suction line ( 7 ) and via a return line ( 13 ) with the water tank ( 5 ), and - a first heating element ( 19a ), which at least partially on the intake ( 7 ), - wherein the first heating element ( 19a ), in the water tank ( 5 ) and / or in the intake line ( 7 ), which is frozen, and - wherein the conveying element ( 3 ), the thawed water in the suction line ( 7 ) via the return line ( 13 ) back into the water tank ( 5 ) to promote. Apparatus according to claim 1, further comprising a second heating element ( 19b ), which at least partially on the return line ( 13 ) is arranged. Device according to one of the preceding claims, further comprising a delivery line ( 8th ), over which the conveying element ( 3 ) with the water injector ( 6 ), and to which a third heating element ( 19c ) is at least partially arranged. Device according to one of the preceding claims, further comprising a fourth heating element ( 19d ), which in the water tank ( 5 ) is arranged. Device according to one of the preceding claims, wherein the first heating element ( 19a ) and / or the second heating element ( 19b ) and / or the third heating element ( 19c ) and / or the fourth heating element ( 19d ) comprise an electrical heating element and / or a hydraulic heat exchanger. Apparatus according to claim 5, wherein the hydraulic heat exchanger is arranged, cooling water of the internal combustion engine ( 2 ) to use to thaw the frozen water. Device according to one of the preceding claims, wherein the conveying element ( 3 ) is set up, in a non-optimal operating point of the conveying element ( 3 ) to generate heat. Device according to one of the preceding claims, wherein the conveying element ( 3 ) is set up to be operated during an active water injection during the thawing process so that a minimum amount of thawed water in the water tank ( 5 ) remains. Internal combustion engine, comprising a water injection device ( 1 ) according to one of the preceding claims.  Internal combustion engine according to claim 9, which is adapted to be operated with gasoline and the Otto principle.  An internal combustion engine according to claim 9 or 10, which is arranged to be operated at reduced power when a reduced amount of water available for injection is smaller than a minimum water injection amount. Method for operating a water injection device ( 1 ) with at least one water injector ( 6 ) and a conveying element for conveying the water, which via a suction line ( 7 ) and via a return line ( 13 ) with a water tank ( 5 ), wherein in the water tank ( 5 ) and / or in the intake line ( 7 ), which is frozen, by a first heating element ( 19a ) is thawed, and the thawed water in the intake line ( 7 ) via the return line ( 13 ) back into the water tank ( 5 ). Method according to claim 12, wherein the conveying element ( 3 ) in a non-optimal operating point of the conveying element ( 3 ) is operated to generate heat. Method according to claim 12 or 13, wherein the conveying element ( 3 ) is operated during an active water injection during the thawing process so that a minimum amount of thawed water in the water tank ( 5 ) remains.

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