KR20190133108A - Water injection system for internal combustion engines with double check valve - Google Patents

Abstract

The present invention relates to a water injection system of an internal combustion engine, and comprises: a water tank (6); a water pump (3) designed to operate in two different directions; at least one water injector (4); a water pipe (5) connecting the water tank (6) and the water injector (4); and a double check valve (2) in the water pipe (5) disposed in a region of the water pipe between the water pump (3) and the water injector (4).

Description

Water injection system for internal combustion engines with double check valves {WATER INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES WITH DOUBLE CHECK VALVE}

The present invention relates to a water injection system of an internal combustion engine including a double check valve. The invention also relates to an internal combustion engine which sprays water directly into the combustion chamber of an internal combustion engine and / or into the suction region of the internal combustion engine.

In the prior art, internal combustion engines including water injection systems are known in a variety of configurations. Water injection can reduce knocking tendencies and lower exhaust gas temperatures. In general, separate water jet systems are known which achieve water jets. For example, DE 10 2015 208 476 A1 discloses an internal combustion engine with a water injection system in which the water injector sprays water in the direction of the inlet valve of the internal combustion engine in the intake region. In this case a water injector is arranged on the inlet channel for supplying combustion air into the combustion chamber of the internal combustion engine. In order to increase the amount of sprayable water per combustion cycle, two water injectors are preferably provided per cylinder. While such a system has been demonstrated in principle, other alternative water spray systems, in particular of reduced complexity and cost, would be desirable.

The object of the present invention is to provide a water injection system which is very simple, economical and especially easy to operate.

The water injection system of the internal combustion engine including the features of claim 1 has the advantage that the installation space can be reduced and the water injection system can be provided at a very low cost. In addition, the pressure retention function of the hydraulic pressure between the double check valve and the water injector can be achieved, and also the fast and reliable emptying of the components and pipes of the water injection system can be achieved, thus preventing freezing of water in the stationary state of the internal combustion engine. do. The water injection system includes a tank, a water pipe connecting the water tank and the water injector, and a water pump disposed in the water pipe. In addition, a double check valve is arranged in the area between the water pump and the water injector in the water pipe. The water pump is designed to operate in two directions.

The dependent claims present preferred embodiments of the invention.

Particularly preferably, the double check valve is designed to be unlocked by low pressure. The low pressure is preferably produced by a water pump operated in the opposite conveying direction, ie in the direction of the water tank. Thus, the unlocking of the double check valve can be realized simply and reliably as opposed to the original flow direction of the check valve. Automatic unlocking can be implemented from the arrival of a predetermined low pressure in the water pipe.

Particularly preferably, the double check valve comprises a control piston, a blocking element, a first return element, a second return element and a sealing sheet, the blocking element on the sealing sheet opening and closing the flow. The control piston is also designed to move the blocking element from the closed position on the sealing sheet to the open position on the sealing sheet. Thus, the unlocking of the check valve is performed, and water can be flowed back from the water pipe in the direction toward the water pump and the water tank.

Also preferably, the double check valve comprises a flexible seated sealing element disposed on the control piston. The flexible sheet sealing element is preferably an impermeable membrane. The flexible sheet-like sealing element is disposed on the control piston and separates the peripheral area from the water area in connection with the periphery on the control piston.

In order to provide a particularly compact structure of the double check valve, the blocking element and the control piston are arranged on a common axis. More preferably, the control piston and the blocking element are arranged to be movable in the axial direction. This realizes opening and closing on the sealing seat on the one hand by linear movement of the blocking element, and unlocking of the check valve on the other hand since the control piston is separated from the sealing seat by the linear movement of the blocking element. .

The sealing sheet is preferably formed on the housing of the double check valve.

Alternatively, a sealing sheet is formed on the control piston. In this way, a more compact configuration of the double check valve can be obtained.

The invention also relates to an internal combustion engine comprising a water injection system according to the invention. The water injection system may be designed to inject water directly into the combustion chamber of the internal combustion engine or into the suction region of the internal combustion engine. It is also possible for an emulsion of fuel and water to be injected into the combustion chamber and / or the intake zone. In this case, the water injection system is connected with the fuel injection system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of a water injection system of an internal combustion engine according to a first embodiment of the present invention,
FIG. 2 is a schematic cross sectional view of the double check valve of the water injection system of FIG. 1 in a closed state,
3 is a schematic cross-sectional view of the double check valve of FIG. 1 in a pressure raising operation with a water pump,
4 is a schematic cross-sectional view of the double check valve of FIG. 1 in an unlocked state, and
5 is a schematic cross-sectional view of a double check valve according to a second embodiment of the present invention in a closed state.

The water injection system 1 of the internal combustion engine will now be described in detail with reference to FIGS. 1 to 4.

As shown in FIG. 1, the water injection system 1 comprises a water tank 6, a water pipe 5, a water pump 3 and a plurality of water injectors 4. The combustion chamber 17 of the internal combustion engine for the water injector 4 is schematically shown, which injects water directly into the combustion chamber. This achieves an improved efficiency of the water jet and further water savings compared to the injection into the suction zone.

Also, as shown in FIG. 1, four water injectors 4 are arranged on the water rail 40. The water pipe 5 connects the water tank 6 and the water rail 40.

In addition, as shown in FIG. 1, a water pump 3 driven by a motor M is arranged in the water pipe 5. The water pump 3 can be operated in two conveying directions, thereby allowing backfeed from the water pipe 5, thus preventing freezing of water in the water pipe 5 and other components of the water injection system. This is explained in detail below.

In addition, in the water pipe, a filter 12 is arranged in the region between the water pump 3 and the water tank 6. The water injection system 1 also comprises a heating device 10 arranged in the region of the water tank 6 so as to achieve freezing or thawing of water after freezing.

In the water pipe 5, also a double check valve 2 is arranged. As shown in FIG. 1, the double check valve 2 is arranged in the region between the water pump 3 and the water injector 4 in the water pipe.

The return pipe 7 connects the water pipe 5 and the water tank 6. In the return pipe 7 a throttle 8 and a check valve 9 are provided. The check valve 9 opens at a predetermined pressure in the water pipe 5, thus preventing overpressure in the water pipe 5 and leading the water back to the water tank.

In addition, FIG. 1 schematically shows a collecting pipe 11 in which a filter 12 is arranged. In this case, for example, tap water or rain water is collected, filtered and guided to the water tank 6, so that the replenishment frequency of the water tank 6 is reduced.

A control unit 14 is provided for controlling the motor M of the water pump 3. The control unit 14 is connected with a pressure sensor 13, which detects the pressure in the water pipe 5 in the region between the double check valve 2 and the water injectors. The control unit 14 operates the water pump 3 according to the pressure level. The control unit 14 also controls back suction of water from the water pipe 5.

2 to 4 show in detail the double check valve 2 arranged in the water pipe 5. 2 shows the closed starting state of the double check valve 2.

As shown in FIG. 2, the double check valve 2 comprises a blocking element 20 and a control piston 23. The first return element 21 is arranged on the blocking element 20. The blocking element 20 seals on the sealing sheet 30 on the housing 25 of the check valve. As shown in FIG. 2, the blocking element 20 is formed as a hollow cylinder with a tapered sealing area, the tapered sealing area lying on the sealing sheet 30. The first return element 21 holds the blocking element 20 in the closed position.

As shown in FIG. 2, the blocking element 20 and the control piston 23 are arranged on a common axis X-X.

The second return element 22 is also provided on the control piston 23. The second return element 22 puts the control piston 23 in the starting state, ie when the water pump is inactive, a small distance A between the plunger area 23a of the control piston 23 and the blocking element 20. It is maintained in the position shown in FIG. Far from the blocking element 20, a flexible sheet-like sealing element 24 is arranged on the end of the control piston 23. The sealing element 24 seals from the peripheral region 15 a water region 16 which is filled with water in the operation of the water pump 3 in the normal operation of the water injection system. The peripheral region 15 is connected with the ambient air via an opening 27 in the cover 26 of the double check valve 2. The control piston 23 is adjacent to a plurality of ribs 26a disposed on the cover 26 so that ambient air can flow behind the membrane.

For easy assembly of the flexible sheet-like sealing element 24, the sealing element can be clamped, for example, between the cover 26 and the housing 25.

The flexible sheet sealing element is preferably a membrane comprising a central opening in which the control piston 23 is arranged.

As shown in FIG. 2, a first connection channel 28 is provided that connects the water region 16 with the first connection 31 facing the water pump. The second connection 32 of the check valve 2 is connected with a water pipe 5 which leads to water injectors 4. The first connecting portion 31 is arranged at an angle of 90 ° with respect to the second connecting portion 32. In this way a particularly compact structure can be obtained and the axial movement of the control piston 23 and the blocking element 26 can be realized simply.

On the housing 25 is also provided a guide region 29 through which the control piston 23 is guided. The blocking element 20 is guided in the second connection 32 by, for example, a plurality of protrusions (not shown) projecting radially outward.

3 shows the normal operating state of the double check valve 2 in which the water pump 3 is operated and the water from the tank 6 is conveyed into the water pipe 5 in the direction towards the water injectors 4. . In this case, water is transferred into the first connection 31 of the double check valve 2, as shown by arrow B in FIG. 3. As a result, the pressure in the region increases, so that the blocking element 20 is separated from the sealing sheet 30 from a predetermined pressure level that depends on the return force of the first return element 21. This is indicated by arrow C in FIG. 3. The water thus flows past the sealing sheet 30 and the blocking element 20, as indicated by arrow D, into the second connection 32 and from there into the water pipe 5 (arrow E).

In addition, since the recesses 20a are formed in the cylindrical region of the blocking element 20, as much water as possible with the smallest possible flow loss can be transferred to the water injectors 4. In this case, the increasing pressure in the first connection 31 acts on the flexible sealing element 24 via the connection channel 28 so that the control piston 23 does not move from the starting position shown in FIG. This is because the pressure in the water region 16 is greater than the ambient pressure in the peripheral region 15.

When the control unit 14 ends the transfer of the water pump 3, the pressure in the first connection 31 decreases, so that the pressure still present in the second connection 32 is reduced by the first return element 21. The blocking element 20 is returned back to the starting position shown in FIG. 2 with the spring force of. In this case, a constant pressure level is maintained in the region of the water pipe 5 between the double check valve 2 and the water injectors 4. In this way, rapid injection of water with high pressure and high dosing accuracy can be prepared without transfer through the water pump 3. The water pump 3 is only activated again when the pressure sensor 13 supplies the control unit 14 with a pressure level lower than a predetermined threshold.

The overpressure can be discharged into the tank 6 at any time through the return pipe 7 in which the throttle 8 and the check valve 9 are arranged (see FIG. 1).

However, when the internal combustion engine is stopped, the water pressure in the water pipe 5 between the double check valve 2 and the water injectors remains. This can cause, for example, the problem of freezing water at low temperatures in winter. In addition, corrosive damage can be caused by stopped water in components of the water injection system. Therefore, after the stop of the internal combustion engine, the components of the water injection system 1 and the water pipe 5 should be free of water. For this purpose, the control unit 14 drives the water pump 3 in the opposite direction, so that the conveying direction of the water pump is reversed. Thus, water from the water pipe can be returned into the water tank 6 via the water pump 3. In this case, the double check valve 2 is unlocked. This state is shown in FIG.

The low pressure is generated in the first connecting portion 31 by the reverse transfer of water by the change of direction of the water pump 3. As soon as the low pressure in the first connection 31 is lower than the pressure in the peripheral region 15, the control piston 23 is linearly moved in the direction of the arrow F. In this case, the return force of the second return element 22 and optionally the friction force on the guide region 29 must still be overcome. Since the control piston 23 is in contact with the blocking element 20, the blocking element 20 also moves linearly in the direction of the arrow F and separates from the sealing sheet 30. Thereby, as indicated by arrow G, water is introduced into the tank 5 through the water pump 3 which is actuated into the first connection 31 and vice versa through the sealing sheet 30 opened from the second connection 32. Reflux.

As shown in FIG. 4, the movement of the control piston 23 is achieved by the flexibility of the sealing element 24. As indicated by arrow H in FIG. 4, air flows from the periphery into the peripheral region 15.

Thus, the entire water pipe 5 is free of water and the components, in particular the water sprayer 4, can also be kept free of water. The control unit 14 controls the water injectors 4 in the open state in order to intake water back from the water injection system without problems, so that air can flow through the water injectors 4 into the water injection system.

In order to achieve a secure opening of the blocking element 20, the control piston 23 comprises a plunger region 23a which engages into the groove 20b on the blocking element 20 and is held in a shape-fitting manner and securely. . In this case, the water flowing back can pass through the long plunger region 23a without problems.

By this, the double check valve 2 can be unlocked by low pressure, water is removed from the water injection system, and the structure of the entire water injection system can be formed very simply. In this case, the double check valve 2 fulfills all functions in the case of normal water transfer through the water pump 3 and all functions in the case of emptying the water injection system. No other component is required for this. In particular, a complicated valve control or the like does not need to be made, and by the configuration according to the present invention of the double check valve 4, the unlocking by the low pressure generated by the water pump 3 can be achieved.

5 shows a double check valve 2 according to a second embodiment of the invention. FIG. 5 also shows a closed steady state, with the double check valve 2 in the closed state and the water pump 3 not in operation.

Unlike the first embodiment, the second embodiment is provided with a control piston 43 formed substantially as a hollow cylinder. The sealing sheet 30 is disposed on the free end of the control piston 43. Thus, the blocking element 20 seals directly on the control piston 43 directly. As shown in FIG. 5, a plurality of elongated openings 43a are formed in the control piston 43 in the region of the first connection 31. This allows water to flow from the outer diameter of the control piston 43 into the interior of the hollow cylinder and vice versa.

Furthermore, as in the first embodiment, a flexible sheet-like sealing element 24 in the form of an impermeable membrane is arranged on the control piston 43. However, the water region and the peripheral region on the sealing element 24 are opposite. As shown in FIG. 5, the connecting channel 28 is guided to the rear of the flexible sealing element 24. On the other hand, the side of the sealing element 24 facing the blocking element is connected to the periphery via the opening 27. Far from the blocking element 20, the end of the control piston 43 is closed by a ball 18.

As shown in FIG. 5, O rings 41 and 42 are disposed on the outer circumference of the control piston to seal the control piston 43. O-rings 41 and 42 seal on the interior of the housing 25. The openings 43a are arranged in the axis X-X direction in the region between the O rings 41 and 42.

When the water pump 3 is actuated, the pressure level in the region of the connection 31 is also increased on the rear region of the sealing element 24 via the connection channel 28. Hydraulic pressure also reaches through the openings 43a into the interior of the control piston 43 and pressurizes the blocking element 20, which blocks the sealing sheet 30 on the control piston 43 from a predetermined pressure level. From the spring force of the first return element 21. In this way, water is conveyed into the water pipe 5 towards the water injectors 4 via the double check valve 2. The control piston 43 stays in the rest position shown in FIG. 5 because the pressure on the sealing element 24 on the water region 16 is greater than on the peripheral region 15. The control piston is adjacent to the first stop 25a on the housing 25.

When the transfer of water through the water pump 3 is finished, the first return element 21 returns the blocking element 20 to the sealed starting position shown in FIG. 5, so that the double check valve 2 is blocked.

If the components of the water injection system 1 and the emptying of the water pipe 5 are now required, the water pump 3 is again operated in the opposite conveying direction, thereby creating a low pressure in the first connection 31. The low pressure propagates backwards on the water region 16 on the interior of the hollow control piston 43 and on the sealing element 24. Thus, since the pressure on the water region 16 is lower than the pressure on the peripheral region 15, the control piston 43 moves in the direction towards the cover 26 against the return force of the second return element 22. do. For the movement of the control piston 43, certain frictional forces appearing on the o-rings 41, 42 must still be overcome. The blocking element 20 touches the second stop 25b on the housing 25 and therefore does not move further in the axial direction, thereby opening the sealing sheet 30 and opening the water to the first connection 32 and the water pipe. It is possible to flow back into the water tank 6 into the first connection 31 through the opening 43a and through the opening 43a through the sealing sheet 30 opened from (5). Thus, the water pipe is emptied.

Thus, as shown in the two embodiments, a double check valve 2 is proposed, which is unlocked by the low pressure generated by the reversal of the feed direction of the water pump 3. Unlocking is done automatically by simply applying low pressure. Thus, a water spray system 1 which is very simple and economical and particularly easy to operate can be provided.

The water injection system according to the invention is preferably used for internal combustion engines, in particular for automotive internal combustion engines.

2: double check valve
3: water pump
4: water sprayer
5: water pipe
6: water tank
15: Surrounding area
16: water zone
20: blocking element
21: first return element
22: second return element
23, 43: control piston
30: sealing sheet
43a: opening

Claims (11)

As water injection system of internal combustion engine,
A water tank (6),
A water pump 3 designed to operate in two different directions,
At least one water sprayer (4),
A water pipe 5 connecting the water tank 6 and the at least one water injector 4, and
In the water pipe (5), a double check valve (2) disposed in the region of the water pipe between the water pump (3) and the water injector (4). 2. Water injection system according to claim 1, wherein the double check valve (2) is designed to be unlocked by low pressure. The double check valve (2) according to claim 1 or 2, wherein the double check valve (2) comprises a shutoff element (20), a first return element (21), a control piston (23), a second return element (22) and a sealing seat (30). And the control piston (23) is designed to move the blocking element (20) from the closed position on the sealing seat (30) to the unlocked open position. 4. The water dispensing system of claim 3, wherein the water injection system further comprises a flexible seated sealing element 24 disposed on the control piston 23, wherein the sealing element 24 on the control piston 23 has a periphery. A water injection system of an internal combustion engine, which separates the connected peripheral zone (15) from the water zone (16). 5. Water injection system according to claim 3 or 4, wherein the blocking element (20) and the control piston (23) are arranged on a common axis (X-X). The water injection system according to any one of claims 2 to 5, wherein the blocking element (20) and the control piston (23) are arranged to be linearly movable in the axis (X-X) direction. The water injection system according to any one of claims 3 to 6, wherein the sealing seat (30) is formed on a housing of the double check valve (2). 8. Water injection system according to claim 7, wherein the control piston (23) comprises a plunge region (23a) in contact with the blocking element (20). The water injection system according to any one of claims 3 to 6, wherein the sealing sheet (30) is formed on the control piston (43). 10. The water injection system according to claim 9, wherein the control piston (43) is a hollow cylinder with an opening (43a). An internal combustion engine, in particular for use in a vehicle, comprising the water injection system according to claim 1.

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