DE102014224348A1 - Direct injection gas injector with improved opening and closing behavior - Google Patents

Abstract

The present invention relates to a gas injector for injecting fuel directly into a combustion chamber of an internal combustion engine, comprising a valve closure element (2) for releasing and closing a passage opening (3), a valve body (4), a first actuator (5) for actuating the valve closure element (Fig. 2), a sealing sleeve (6) which is movably arranged in the valve body (4), a first sealing seat (11) between the sealing sleeve (6) and the valve closing element (2), and a second sealing seat (12) between the sealing sleeve (6 ) and the valve body (4), wherein the valve closing element (2) is at least partially disposed in the sealing sleeve (6), and wherein the valve closing element (2) to be released and to be closed passage opening (3) is provided in the sealing sleeve 6.

Description

State of the art

The present invention relates to a direct-injection gas injector, which has an improved opening behavior and an improved closing behavior.

In addition to liquid fuels, gaseous fuels such as e.g. Natural gas or hydrogen, used. In direct injection gas injectors in a combustion chamber results in comparison to liquid fuel injection injectors due to the differently introduced volumes of fuels another opening and closing behavior. Also, the direct injection of gaseous fuels directly into a combustion chamber of a combustion engine still offers considerable potential for improvement. With gaseous fuels, larger fuel volumes must be introduced than in comparison with liquid fuels.

Disclosure of the invention

The direct injection gas injector according to the invention for injecting gaseous fuel directly into a combustion chamber of an internal combustion engine having the features of claim 1 has the advantage that an improved opening behavior and an improved closing behavior of the gas injector is achieved. In particular, switching times can be kept very small, so that a fast and safe response of the gas injector is possible. This is inventively achieved in that the gas injector comprises a valve closing element for releasing and closing a passage opening a sealing sleeve. The sealing sleeve is movably arranged in a valve body. A first actuator is provided to actuate the valve closure member. The valve closing element is at least partially disposed in the sealing sleeve. Furthermore, the to be closed by the valve closing element and to be closed passage opening in the sealing sleeve itself is provided. In this case, a first sealing seat between the sealing sleeve and the valve closing element is provided and a second sealing seat is provided between the sealing sleeve and the valve body. This makes it possible for fuel to flow through the passage opening and thereby through the interior of the sealing sleeve after opening the passage opening, as well as past the outer circumference of the sealing sleeve. This can ensure a high volume flow during the opening period.

The dependent claims show preferred developments of the invention.

Preferably, the gas injector comprises a downstream in the flow direction of the gas injector of the sealing sleeve pressure compensation chamber and injection holes. The spray holes are downstream of the pressure equalization chamber in the direction of flow of the gas injector. The gaseous fuel is then injected directly into the combustion chamber of the internal combustion engine via the injection holes. By the sealing sleeve downstream pressure compensation chamber, it is possible that in the open state, an almost equal pressure in the flow direction before and after the sealing sleeve is achieved. Thereby, the valve closing element can be operated at least temporarily pressure balanced. As a result, in particular, the valve closing element can be lifted out of the seat with only little force and thus a fast and reliable opening and closing behavior can be achieved. As a result, in particular switching times can be kept very short and switching times are met exactly.

A particularly fast pressure equalization in the Injektorbereichen before and after the sealing sleeve is achieved when there is a throttle point between the pressure equalization chamber and the spray holes. As a result, after the valve-closing element has been lifted off, a rapid increase in pressure in the pressure compensation chamber is achieved by the passage opening provided in the sealing sleeve, and thus a further opening operation of the valve-closing element can be possible without great force.

More preferably, the injection holes are formed directly in the valve body. This allows a very compact and simple construction.

According to a further preferred embodiment of the invention, a first diameter of the first sealing seat is smaller than a second diameter of the second sealing seat. By choosing a small diameter at the first sealing seat in particular a necessary opening force of the valve closing element opening force is significantly reduced.

In order to achieve a tightness in the closed state of the gas injector and an improved bounce behavior during the closing operation, the first and / or second sealing seat is preferably formed as an elastomer sealing seat with at least one elastomeric element, preferably with two elastomeric elements.

According to a further preferred embodiment of the present invention, the gas injector further comprises a third sealing seat between the sealing sleeve and the valve body. The third sealing seat is preferably a metal or ceramic sealing seat. As a result, by means of the third sealing seat, in particular protection of the first and / or or second sealing seat can be achieved before the high combustion chamber temperatures. The third elastomer-free sealing seat is preferably arranged closer to the combustion chamber than the first and second sealing seat.

In order to have a structure as compact and as small as possible, the valve closing element preferably has a driver in order to take along the sealing sleeve during an opening process of the gas injector after covering a predetermined free travel. This allows a very inexpensive and simple construction.

Alternatively, a second actuator is provided which is adapted to lift the sealing sleeve from its sealing seat. In this case, for example, the first actuator and the second actuator are controlled in dependence on one another by means of a control unit.

According to a further preferred embodiment of the present invention, the gas injector further comprises a first spring element which acts on the sealing sleeve to hold the sealing sleeve in the closed state. During the opening process, the spring force of the first spring element must then be overcome by means of the first actuator.

The gas injector preferably has a second spring element which acts on the closing element in order to hold the closing element in the closed state.

The valve closing element is preferably an inwardly opening valve closing element.

Furthermore, the present invention relates to an internal combustion engine comprising a combustion chamber and a gas injector according to the invention, wherein the gas injector is arranged directly on the combustion chamber to inject gaseous fuel directly into the combustion chamber.

drawing

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

1 a schematic sectional view of a direct-injection gas injector according to an embodiment of the invention in the closed state.

Preferred embodiment of the invention

The following is with reference to 1 a gas injector 1 according to a first preferred embodiment of the invention described in detail.

How out 1 can be seen, includes the gas injector 1 a valve closing element 2 which is a valve needle in this embodiment. XX denotes an axial direction of the gas injector. The valve closing element 2 gives a passage opening 3 free, which in this embodiment in a sealing sleeve 6 is provided.

How out 1 it can be seen, is the sealing sleeve 6 a sleeve-shaped element with a jacket region 60 and a floor 61 , wherein the passage opening 3 in the ground 61 is formed. Furthermore, on the sealing sleeve 6 another ring-shaped, inwardly directed stop 62 from the passage opening 3 opposite end of the sealing sleeve 6 intended.

The gas injector 1 further includes a magnetic actuator 5 with an anchor 50 , a coil 51 and a pole 52 , which is constructed in a known manner. Alternatively, a piezo actuator can also be used.

The anchor 50 is with the valve closing element 2 connected and allows when energizing the coil 51 a lifting of the valve closing element 2 from a first sealing seat 11 ,

How out 1 is apparent, is the first sealing seat 11 while between the valve closing element 2 and the sealing sleeve 6 at the passage opening 3 intended.

A second sealing seat 12 is between the sealing sleeve 6 and a valve body 4 intended. The valve body 4 itself has several spray holes 9 on.

On the valve closing element 2 is also a driver 20 formed, which with the stop 62 the sealing sleeve 6 comes after covering a predetermined free path F in contact. Thereby, during the opening operation of the valve closing element 2 After covering the free travel F, the sealing sleeve 6 also be moved.

The sealing sleeve 6 is by means of a first spring element 18 in the direction of a combustion chamber 10 an internal combustion engine biased.

Furthermore, a third sealing seat 13 between the sealing sleeve 6 and the valve body 4 intended. The third sealing seat 13 is an elastomer-free sealing seat and preferably has two metallic sealing partners.

For guiding the valve closing element 2 is also a guide disc 15 in the valve body 4 fixed. In the guide disc 15 are several holes 17 provided for passing gaseous fuel. The valve closing element 2 is at a leadership area 16 the guide disc 15 guided.

The valve closing element 2 is further by means of a second spring element 19 biased towards the combustion chamber. The guide disc 15 at the same time serves as a spring support for the first spring element 18 , The first sealing seat 11 comprises a first elastomeric element 31 , which in this embodiment on the sealing sleeve 6 is arranged. A second elastomeric element 32 is at the second sealing seat 12 provided, wherein on the sealing sleeve 61 an outwardly directed flange 63 is provided, which on the second elastomeric element 32 seals.

A first diameter D1 of the first sealing seat 11 is smaller than a second diameter D2 of the second sealing seat 12 , Furthermore, in the direction of flow of the gas injector 1 after the sealing sleeve 6 a pressure compensation room 7 provided (cf. 1 ). The pressure compensation room 7 lies between the sealing sleeve 6 and the combustion chamber end of the valve body 4 , The spray holes 9 in the valve body 4 are arranged in the valve body such that a throttle path 8th or just a gap in the flow path from the surge tank 7 to each injection hole 9 is available.

The operation of the gas injector according to the invention 1 is as follows. When an injection of gaseous fuel is made, the solenoid actuator becomes 5 activated and the anchor 50 against the inner pole 52 of the magnetic actuator tightened. This raises the valve closing element 2 which with the anchor 50 is firmly connected, from the first sealing seat 11 and gives the passage opening 3 free. This allows gaseous fuel through the interior of the sealing sleeve 6 past the valve closing element 2 through the passage opening 3 in the pressure equalization room 7 stream.

Due to the throttle point through the throttle path 8th between the pressure compensation room 7 and the spray holes 9 quickly becomes a predetermined pressure level in the surge tank 7 constructed, which is approximately equal to the pressure level of the gaseous fuel in front of the passage opening 3 , As a result, a pressure equalization in the region of the combustion chamber-side end of the valve closing element 2 achieved, so that a further opening operation of the valve closing element 2 without much effort is possible. In the opening case, the valve closing element 2 thus temporarily pressure balanced. When closed, the system pressure of the gaseous fuel assists the inwardly opening valve closure member in sealing.

The valve closing element 2 is partially in the sealing sleeve 6 arranged.

As the first diameter D1 of the first sealing seat 11 is relatively small, the lifting of the valve closing element 2 from the first seal seat 11 done with relatively little effort.

According to the invention is thus by the provision of the throttle path 8th during the opening process between the pressure equalization chamber 7 and the spray holes 9 an effectively pneumatically effective pressure differential across the port 9 between the combustion chamber side of the sealing sleeve 6 and the combustion chamber side facing away from the sealing sleeve 6 receive. As a result, after covering the free travel F thus the sealing sleeve 6 also be pulled with little pressure in the direction of arrow A, so now a large cross section for supplying gas to the spray holes 9 is present, the throttle point at the throttle path 8th with the movement (arrow B) of the sealing sleeve 6 expanding more and more, until it has completely disappeared and no throttle effect is present.

Thus, according to the invention, a gas injector for direct injection of gaseous fuel into a combustion chamber of an internal combustion engine can be provided, which has very short response times for both opening and closing. By providing a plurality of sealing seats is also a high density of the gas injector 1 ensured, in particular, the high pressure of the gaseous fuel, the sealing sleeve 6 in the second sealing seat 12 and the third sealing seat 13 suppressed. The third sealing seat 13 acts as a stop to limit a return travel of the sealing sleeve 6 , In this case, the gas injector according to the invention has a compact and inexpensive to produce structure without complicated components, so that the gas injector is particularly suitable for mass production.

Furthermore, according to the invention by different design of the length of the free path F of the gas injector 1 be relatively easily adjusted to different requirements and conditions for direct injection of gaseous fuel.

Claims (14)

Gas injector for injecting fuel directly into a combustion chamber of an internal combustion engine, comprising - a valve closing element ( 2 ) for releasing and closing a passage opening ( 3 ), - a valve body ( 4 ), - an actuator ( 5 ) for actuating the valve closing element ( 2 ), - a sealing sleeve ( 6 ), which are movable in the valve body ( 4 ) is arranged A first sealing seat ( 11 ) between the sealing sleeve ( 6 ) and the valve closing element ( 2 ), and - a second sealing seat ( 12 ) between the sealing sleeve ( 6 ) and the valve body ( 4 ), - wherein the valve closing element ( 2 ) at least partially in the sealing sleeve ( 6 ), and - wherein the valve closing element ( 2 ) to be released and closed passage opening ( 3 ) in the sealing sleeve ( 6 ) is provided. Gas injector according to claim 1, further comprising a in the flow direction of the gas injector of the sealing sleeve ( 6 ) downstream pressure compensation chamber ( 7 ) and at least one injection hole ( 9 ), wherein the injection hole ( 9 ) in the flow direction of the gas injector the pressure compensation chamber ( 7 ) is connected downstream. Gas injector according to claim 2, characterized in that between the pressure equalization chamber ( 7 ) and the injection hole ( 9 ) a throttle point ( 8th ) is provided. Gas injector according to claim 3, characterized in that the throttle point ( 8th ) between the sealing sleeve ( 6 ) and the valve body ( 4 ) is trained. Gas injector according to one of claims 2 to 4, characterized in that the injection hole ( 9 ) in the valve body ( 4 ) is provided. Gas injector according to one of the preceding claims, characterized in that a first diameter (D1) of the first sealing seat ( 11 ) is smaller than a second diameter (D2) of the second sealing seat ( 12 ). Gas injector according to one of the preceding claims, characterized in that the first sealing seat ( 11 ) and / or the second sealing seat ( 12 ) as Elastomerdichtsitz with at least one elastomeric element ( 31 . 32 ) is trained. Gas injector according to one of the preceding claims, further comprising a third sealing seat ( 13 ), wherein the third sealing seat ( 13 ) between the sealing sleeve ( 6 ) and the valve body ( 4 ) is provided. Gas injector according to claim 8, characterized in that the third sealing seat ( 13 ) is a metal sealing seat or a ceramic sealing seat. Gas injector according to claim 8 or 9, characterized in that the third sealing seat ( 13 ) closer to the combustion chamber than the first sealing seat ( 11 ) and the second sealing seat ( 12 ) is arranged. Gas injector according to one of the preceding claims, characterized in that the valve closing element ( 2 ) a driver ( 20 ) in order, in an opening operation of the gas injector after covering a predetermined free travel (F), the sealing sleeve ( 6 ). Gas injector according to one of claims 1 to 10, characterized by a second actuator, which is arranged, the sealing sleeve ( 6 ) from the second sealing seat ( 12 ). Gas injector according to one of the preceding claims, further comprising a first spring element ( 18 ), which on the sealing sleeve ( 6 ) acts to the sealing sleeve ( 6 ) in the closed state. Gas injector according to one of the preceding claims, characterized by a second spring element ( 19 ), which on the closing element ( 2 ) acts to the closing element ( 2 ) in the closed state.

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