KR20170092551A - Gas injector with improved contact surfaces - Google Patents

Abstract

The present invention relates to a gas injector for directly injecting gaseous fuel into a combustion chamber of an internal combustion engine, the gas injector comprising a valve closing element (2) for opening and closing a through hole (3) on a sealing sheet (4) A first part 5 having a hardness and a second part 6 having a second surface hardness. When the gas injector is in a predetermined state, the first component 5 contacts the second component 6, and the surface hardness of the first component 5 is greater than the surface hardness of the second component.

Description

≪ Desc / Clms Page number 1 > GAS INJECTOR WITH IMPROVED CONTACT SURFACES <

The present invention relates in particular to a gas injector for direct injection into a combustion chamber, with an improved contact surface between the inner pole of the gas injector and the armature.

In recent years, in addition to liquid fuels, gaseous fuels such as natural gas or hydrogen are also used in the automotive field. Due to the manufacturing tolerances of the components, the parts which are in contact during operation of the gas injector may not be in perfect geometry, for example the stops may not touch the entire contact surface. As a result, a high contact stress occurs when the parts collide with each other. This occurs especially between parts of the magnetic actuator, in particular between the armature and the inner pole. In the case of liquid fuels, the shape of the armature and inner pole is chosen such that only a relatively small proportion of the end face is actually in contact with the other part to prevent hydraulic bonding. As a result, a fast closing time of the injector can be achieved. In the case of liquid fuels, the actual contact surface of the components is as small as possible. However, the liquid fuel prevents too high a collision of the part just before the mechanical stop, because the liquid is squeezed out of the contact area and the moving part is delayed. Therefore, the moving speed of the moving part is lowered immediately before the collision, thereby reducing the static load. In the case of gaseous fuel, the compression effect does not occur and the moving part hits other parts without braking. This results in a larger contact load in the case of liquid fuels. In the case of gaseous fuels, however, no hydraulic bonding occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gas injector in which a front contact is made between two parts that are in contact with each other during operation.

A gas injector according to the present invention for direct injection of gaseous fuel into the combustion chamber of an internal combustion engine having the features of claim 1 can be used between two parts in contact with each other during operation, for example between an inner pole and an armature, And thus does not exhibit any disadvantages to the dynamics of the closing behavior and the opening behavior. As a result, the contact stress can be greatly reduced. Further, according to the present invention, since the manufacturing tolerances can be well compensated, reliable and long-lasting continuous operation of the gas injector is possible. This is achieved in accordance with the invention by a gas injector comprising a valve closing element for opening and closing a through hole on a sealing sheet, a first part having a first surface hardness and a second part having a second surface hardness. In a given state of the gas injector, the first and second parts are in contact. The predetermined state is preferably a fully opened state or a closed state. In this case, the hardness of the first part is larger than the hardness of the second part. Controlled abrasion of the softer surface is achieved because the hardness of the parts that come into contact with each other and then to each other, which are separated from each other, are different. Thus, a softer layer is sacrificed in part to provide tolerance compensation and the like. Plastic deformation may also occur in the softer layer of the surface. A softer surface thus forms a deformed surface. Wear or deformation of a softer surface occurs after a short inflow process, so that the contact surface between the first and second parts that are actually present during operation becomes larger and the contact stress between the first and second parts decreases. After a constant inflow time, a steady state without further wear or further plastic deformation is obtained.

The dependent claims present preferred improvements of the present invention.

Particularly preferably, there is a surface contact between the first and second parts in a predetermined state. As a result, a very low contact load can be achieved during contact between the parts.

Particularly preferably, the second component comprises a coating. The hardness of the coating is less than the surface hardness of the first component. As a result, the hardness difference between the parts can be achieved individually by simply coating one of the parts.

The first component is particularly preferably the inner pole of the magnetic actuator and the second component is the amateur of the magnetic actuator. The armature is connected to the valve closing member. Particularly preferably, the entire surface of the inner pole facing the combustion chamber is in contact with the surface of the armature. Alternatively or simultaneously, the entire surface of the armature away from the combustion chamber contacts the inner pole. As a result, a large contact surface is secured between the inner pole and the armature.

Alternatively, the first and second parts are each formed as a stop to limit the stroke of the gas injector. Also alternatively, the first and second components form a sealing sheet of the gas injector.

Also preferably, the surface hardness of the first component is at least 50% greater than the surface hardness of the second component. Preferably, the surface hardness of the first part is at most 500% greater than the surface hardness of the second part. The surface hardness of the first component is preferably about 1000 HV, and the surface hardness of the second component is preferably about 200 HV to 300 HV.

According to another preferred embodiment of the present invention, the thickness of the coating of the second part is in the range of 5 [mu] m to 30 [mu] m, in particular in the range of 5 [mu] m to 10 [mu] m.

More preferably, the gas injector comprises an inflow medium disposed between the first and second parts. The inflow medium promotes controlled wear or controlled deformation. As the infusion medium, for example, an emulsion such as a water / oil mixture, or a suspension, for example water or oil containing abrasive particles, may be used.

It is particularly preferred that the surface of the first component is a chrome surface. As the coating for the second part, there can be used tin, nickel, embedded attenuated particles, for example nickel, zinc, copper or copper alloy (bronze, brass) with PTFE and a softer chromium layer / RTI > The present invention also relates to an internal combustion engine comprising a combustion chamber and a gas injector according to the invention, wherein the gas injector is disposed directly in the combustion chamber for direct injection of gaseous fuel into the combustion chamber.

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

1 is a schematic cross-sectional view of a gas injector according to a first embodiment of the present invention.
Figure 2 is a schematic cross-sectional view of the contacting parts of Figure 1 prior to the inflow step.
Figure 3 is a schematic cross-sectional view of parts that come into contact after the inflow step.

A gas injector 1 according to a preferred embodiment of the present invention is described in detail below with reference to Figs.

As can be seen from Fig. 1, the gas injector 1 comprises a valve closing element 2 which in this embodiment is a valve needle. In this case, the valve closing element 2 opens or closes the through hole 3 in the sealing sheet 4.

The gas injector 1 is disposed directly in the combustion chamber 10. As a result, the gaseous fuel can be directly injected into the combustion chamber 10.

The armature 6 is arranged in the valve closing element 2. The armature 6 and the inner pole 5 together with the coil 9 form a magnetic actuator for operating the gas injector 1. The inner pole 5 forms the first part, and the armature 6 forms the second part, which are in contact with each other in a predetermined state of the gas injector, that is, in a completely open state.

The inner pole 5 comprises a first coating 11. The amateur 6 includes a second coating 12 and a third coating 13 disposed on the second coating 12. Thus, in the fully open state, the third coating 13 and the first coating 11 are in contact. The hardness of the third coating (13) is lower than the hardness of the first coating (11).

Reference numeral 8 denotes a restoration element, which restores the valve closing element 2 to the closed start position shown in Fig.

In order to open the gas injector 1, the magnetic actuator is operated in a known manner, so that the armature 6 is pulled in the direction of the arrow A with respect to the inner pole 5. Then, the armature 5 comes into contact with the inner pole 5 after overcoming the intermediate gap between the armature 6 and the inner pole 5. This is indicated by the arrow A in Fig.

Fig. 2 shows the state of the gas injector prior to the inflow stage in which there is a predetermined tilted position between the armature 6 and the inner pole 5 due to manufacturing tolerances. This is indicated by the conical gap 14 in Fig.

Controlled wear of the softer third coating 13 can be achieved due to the different hardness between the first coating 11 and the third coating 13 that come into contact with each other during operation. Thus, the third coating 13 forms a sacrificial layer that is partially sacrificed during the inflow process to compensate for manufacturing tolerances. The softer third coating 13 also undergoes plastic deformation, so that the third coating 13 can form a strained layer.

As shown in the comparison of FIG. 2 and FIG. 3, there is complete surface contact between the third coating 13 and the first coating 11 after the inflow step, i. E. Thus, a stable state is achieved without further wear. Due to the surface contact between the first and second parts, i.e. the inner pole 5 and the armature 6, the contact stress between the parts is reduced. Thus, wear and plastic deformation during the inflow process decreases until a stable final state of the contact geometry is achieved. In this case, the contact stress is minimal, because the actual contact surface is the maximum. Since gaseous fuel is used in accordance with the present invention, there is no risk of hydraulic adhesion due to the large contact surface, which may occur in the use of liquid fuel. No temperature dependence of the contact surface is also seen. The thickness of the third coating 13 is, for example, in the range of 5 탆 to 10 탆.

The first coating 11 on the inner pole 5 may be, for example, a chromium coating. The second coating 12 directly attached to the armature 6 may likewise be a chromium coating, preferably the same coating as the first coating on the inner pole 5. [ The third coating 13, which is a softer coating than the first coating 11, is for example a tin containing, nickel containing, zinc containing or copper containing coating.

To support the inflow process during controlled wear, a suspension with an infusion medium, for example an emulsion or abrasive particles, can preferably be used. Alternatively or additionally, additives which are used for the lubrication of the inflow process may be provided in the third coating 13, for example.

2 valve closing element
4 sealing sheet
5, 6 parts
10 combustion chamber

Claims (11)

A gas injector for injecting direct gaseous fuel into a combustion chamber of an internal combustion engine,
A valve closing element 2 for opening and closing the through hole 3 in the sealing sheet 4,
- a first part (5) having a first surface hardness, and
- a second part (6) having a second surface hardness,
- the first part (5) in contact with the second part (6) in a predetermined state of the gas injector,
- the surface hardness of the first part (5) is higher than the surface hardness of the second part (6). 2. The gas injector according to claim 1, wherein there is a surface contact between the first part (5) and the second part (6) in contact. 3. Gas injector according to claim 1 or 2, characterized in that the second part (6) comprises a coating (13). 4. A valve according to any one of claims 1 to 3, characterized in that the first part (5) is the inner pole of the magnetic actuator and the second part (6) is the inner pole of the magnetic actuator And the gas injector. 5. A method according to claim 4, characterized in that the entire surface of the inner pole towards the combustion chamber is in contact with the armature in contact and / or the entire surface of the armature away from the combustion chamber is in contact with the inner pole in contact Injector. 5. A method according to any one of claims 1 to 4, wherein the first part (5) and the second part (6) are formed as stop parts to limit the stroke of the gas injector, or the first part 5) and the second part (6) are formed as a sealing sheet of the gas injector. 7. Gas injector according to any one of claims 1 to 6, characterized in that the surface hardness of the first part (5) is at least 50% greater than the hardness of the second part (6). 8. A gas injector according to any one of claims 3 to 7, characterized in that the thickness of the coating (13) is in the range of 5 [mu] m to 30 [mu] m. 9. A gas injector according to any one of claims 1 to 8, characterized in that the gas injector further comprises an inflow medium disposed between the first part (5) and the second part (6). 10. A method according to any one of claims 3 to 9, wherein the coating (13) is a nickel coating or a copper coating or a copper alloy comprising tin coating or nickel coating or embedded attenuated particles or a coating having a hardness in the range of 300 to 500 HV Characterized in that it is a softer chrome coating. An internal combustion engine comprising a gas injector (1) and a combustion chamber (10) according to any one of claims 1 to 10, characterized in that the gas injector (1) is arranged to inject gaseous fuel directly into the combustion chamber And is disposed directly in the combustion chamber (10).

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