EP2791495B1

EP2791495B1 - An injection valve resistant to cavitation

Info

Publication number: EP2791495B1
Application number: EP12768793.7A
Authority: EP
Inventors: Alper COMERT; Suat SACARCELIK; Rahman CAKIR; Ozan DINCEL; Ediz ILHAN; Veyzat GAZI; Serkan ELMALL; Erhan KAYAR; Barkin ARAK; Nese YENIGUN; Tuna AYDIN; Dogan Vardar
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2011-10-01
Filing date: 2012-10-01
Publication date: 2016-08-24
Anticipated expiration: 2032-10-01
Also published as: EP2791495A1; WO2013045690A1

Description

TECHNICAL FIELD

The present invention relates to an injection valve utilized for spraying fuel into the combustion chamber in internal combustion engines and comprising an armature and a valve piece provided at the continuation of said armature.

PRIOR ART

Injection valves are used for spraying fuel into the combustion chamber in internal combustion engines. Injection valves are obtained by bringing pluralities of pieces together and the pieces are directly or indirectly in connection with each other. The injection valves comprise different members according to the operation principles thereof, and the injection valves comprising a valve piece is one of these injection valves.
Said injection valves comprise a valve piece, and armature and valve ball provided on the valve piece. Such injection valves are essentially disclosed in the patent WO 2011 051060 (A1 ). Moreover, in the patent application DE 10 2006 021 741 (A1 ), the improvements related to the valve piece and to the valve bearing thereon are disclosed. In order to provide the transfer of the high pressured fuel towards the armature and through the valve piece, there is a hole on the valve piece. The high pressured fuel, existing inside the valve piece, passes to the armature region through the hole. Particularly in cases like high way drive and under continuous pressure, valve ball keeps the hole open permanently and fuel transfer is provided through the hole towards the armature.
In the fuel, which is under the affect of high pressure, and particularly in overload conditions, cavitation bubbles are formed. These bubbles blow out on the valve bearing on the valve piece or during the passage from the valve piece to the armature and thereby said bubbles lead to cavitation and abrasions. This affects the usage lifetime of the valve piece and of the armature. Moreover, the abrasions and cavitation, which occur in the seating part, prevent sealing in required cases.
As a result, because of the abovementioned problems, an improvement is required in the related technical field.
Furthermore, the patent application DE 10 2006 000 256 A1 discloses an injection valve with a control valve, whereby the valve seating is surrounded by a ring shaped notch.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to an injection valve where sealing in the seating part existing between the valve piece and the armature is provided in a figurative manner and where cavitation is prevented, in order to eliminate the abovementioned problems and to bring new advantages to the related technical field.
The main object of the present invention is to provide an injection valve where the cavitation, formed between the valve piece and the armature, is prevented by means of formal precautions.
Another object of the present invention is to provide an injection valve where the sealing between the valve piece and the armature is provided by means of figurative precautions.
In order to realize all of the abovementioned objects and the objects which are to be obtained from the detailed description below, the present invention relates to an injection valve comprising an input region through which the fuel enters; an armature having a wide region which is provided at the continuation of said input region and having a narrow region with a seating surface at the continuation thereof; a valve piece which has a seating part and which is provided at the continuation of said armature and which is positioned so as to define a valve bearing in between; a control volume provided inside said valve piece; and a hole which is provided at said valve piece between said valve bearing and said control volume. Said injection valve comprises at least one seating region where the fuel, exiting from said hole towards the valve bearing, is sealed; a sealing surface, which has a linear cross section, of the part which at least covers the hole between the armature and the valve piece in said seating region; and cut-outs on the valve piece and on the armature so that the fuel, comprising cavitation bubbles exiting the hole, is able to flow substantially far away from the edges of the armature and of the valve piece inside the valve bearing.
In a preferred embodiment of the subject matter invention, the passage from said wide region, provided at the armature, to said narrow region comprises at least one inclined edge; the valve piece comprises angled edges with respect to each other in order to provide the free spreading of the fuel, exiting the hole of the seating region, in the valve bearing; and there is at least one passage edge which is embodied at the lower elevation at a certain distance in X direction from the point where the hole is opened into the valve bearing.
According to the invention, there is at least one seating edge between the seating region and the end of the hole at a vicinity of the seating region. In another preferred embodiment of the subject matter invention, said seating edge is curved.
In another preferred embodiment of the subject matter invention, the passage from said wide region, provided at the armature, to said narrow region comprises at least one inclined edge which is positioned in X direction and at a certain angle to said flat edge; at least one seating surface which is provided at the continuation of said inclined edge and which is positioned substantially parallel to the flat edge; at least one passage edge which is positioned substantially parallel to the flat edge and which is provided at the continuation of said second angled edge of said seating part which is provided at the valve piece; at least one third angled edge which is provided at the continuation of said passage edge and which is positioned in opposite direction to the X direction and so as to make a certain angle with the passage edge; at least one fourth angled edge which is provided at the continuation of said third angled edge and which is positioned so as to make a certain angle with the third angled edge; and at least one seating edge which is provided between said fourth angled edge and said hole and where the valve piece is in linear contact with the armature.
In order for the embodiment and the advantages of the subject matter invention to be understood in the best manner with the additional elements, it has to be evaluated with the detailed description and with the figures explained below.

BRIEF DESCRIPTION OF THE FIGURES

In Figure 1, a cross sectional view of an injection valve is given.
In Figure 2, the zoomed cross sectional view of an injection valve is given.
In Figure 3, the zoomed cross sectional view of an injection valve is given.
In Figure 4, the zoomed cross sectional view of the seating region belonging to an injection valve is given.

REFERENCE NUMBERS

 10 Injection Valve
     11 Input Region
     12 Needle Region
     13 Body
     14 Valve Bearing
     20 Seating Region
     21 Space
     30 Valve Piece
     31 High Pressure Part
     32 Control Volume
     33 Hole
            331 First Reg ion
            332 Intermediate Region
            333 Second Region
     34 Seating Part
            341 First Angled Edge
            342 Second Angled Edge
            343 Third Angled Edge
            344 Fourth Angled Edge
            345 Seating Edge
            346 Upper Edge
            347 Passage Edge
            40 Armature
     41 Wide Region
            411 Flat Edge
     42 Narrow Region
            421 Inclined Edge
            422 Seating Surface
            α : Angle Between Upper Edge - First Angled Edge
            θ : Angle Between First Angled Edge - Second Angled Edge
            β : Angle Between Passage Edge - Third Angled Edge
            µ : Angle Between Third Angled Edge - Fourth Angled Edge

THE DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, the subject matter improvement is explained with references to examples without forming any restrictive effect in order to make the subject more understandable. Accordingly, in the detailed description and in the figures below, an injection valve (10) is disclosed which is used for spraying fuel into the combustion chamber (not illustrated in the figure) in internal combustion engines (not illustrated in the figure) and where the sealing between the armature (40) and the valve piece (30) is provided by means of figurative precautions and where the cavitation formation in the valve bearing (14) part of the valve piece (30) is prevented.

With reference to Figure 1, an injection valve (10) is illustrated. Said injection valve (10) comprises an input region (11) through which the fuel enters, and a needle region (12) through which the fuel is sprayed to the combustion chamber. Said input region (11) and said needle region (12) are generally provided on a body (13) which has a circular cross section. At the continuation of the input region (11), an armature (40) in X direction is in connected form. Said armature (40) generally has a circular cross section and it is positioned so as to be coaxial with the injection valve (10). In general, the armature (40) comprises two parts. These parts are the wide region (41) and the narrow region (42). Said wide region (41) is positioned so as to correspond to the vicinity of the input region (11) of the injection valve (10). There is said narrow region (42) at the continuation of the wide region (41). The narrow region (42) is positioned so as to be coaxial with the wide region (41). The diameter of the narrow region (42) is smaller than the diameter of the wide region (41). The inclined edge (421) is in connection to the flat edge (411), which is defined on the wide region (41), at a certain angle. Said inclined edge (421) is embodied so as to have a certain length. A seating surface (422) is defined at the continuation of the inclined edge (421). Said seating surface (422) is positioned so as to make a certain angle with the inclined edge (421) and so as to be parallel to said flat edge (411). The inclined edge (421) and the seating surface (422) are provided on the narrow region (42).

A valve piece (30) is in connection to the injection valve (10) at the continuation of the armature (40) in the X direction and between the input region (11) and the needle region (12). Said valve piece (30) is coaxial with the injection valve (10) and with the armature (40). The valve piece (30) is positioned so as to separate the high pressure region (not illustrated in the figure) inside the injection valve (10) from the low pressure regions (not illustrated in the figure) and the valve piece (30) provides the sealing between said high pressure and low pressure regions. The part of the valve piece (30) which is at a vicinity of the high pressure region is defined as the high pressure part (31). There is a control volume (32) which is embodied at said high pressure part (31). Said control volume (32) is in the region where the high pressured fuel exists in the valve piece (30) and which is adjacent to the valve piston (not illustrated in the figure). The control volume (32) has a circular cross section and it is positioned inside the valve piece (30) so as to be smaller than the diameter of the high pressure part (31) and so as to be coaxial with the valve piece (30). On the valve piece (30), a seating part (34) is provided at the continuation of the high pressure part (31). Said seating part (34) is positioned so as to be adjacent to the armature (40) and to the low pressure region and so as to be in the opposite direction to direction X. The diameter of the seating part (34) is embodied so as to be greater than the diameter of the high pressure part (31). The seating part (34) has a W-like view when viewed from the cross section. The top edge of the seating part (34) at a vicinity of the input region (11) in opposite direction to direction X is defined as the upper edge (346). Said upper edge (346) exists in the same horizontal level with the flat edge (411) of the armature (40). The valve piece (30) rests onto the other members of the injection valve (10) by means of the upper edge (346). There is a first angled edge (341) which is in connection with the upper edge (346). Said first angled edge (341) is positioned at a vicinity of the armature (40) and in X direction and so as to make a certain angle with the upper edge (346). The angle between the first angled edge (341) and the upper edge (346) is defined as the α angle. At the continuation of the first angled edge (341), there is the second angled edge (342) in connection. The angle between the second angled edge (342) and the first angled edge (341) is defined as the θ angle. The θ angle is greater than the α angle. There is a passage edge (347) at the continuation of the second angled edge (342). Said passage edge (347) is positioned so as to be parallel to the upper edge (346) and to the flat edge (411). There is a third angled edge (343) connected at the continuation of the passage edge (347). Said third angled edge (343) is positioned so as to make a certain angle with the passage edge (347) and at an opposite direction to the X direction. The angle between the passage edge (347) and the third angled edge (343) is defined as the β angle. At the continuation of the third angled edge (343), there is a fourth angled edge (344) in connection. Said fourth angled edge (344) makes a certain angle with the third angled edge (343) and this angle is called the µ angle. The third angled edge (343) ends so as to be adjacent to the seating surface (422) of the armature (40). The third angled edge (343) and the fourth angled edge (344) extends towards the axis of the injection valve (10) from the passage edge (347).

With reference to Figure 3, a hole (33) is embodied to the valve piece (30). Said hole (33) is positioned so as to begin in an adjacent manner to the armature (40) on the valve piece (30) and so as to end in the control volume (32). The hole (33) is coaxial with the valve piece (30). The hole (33) essentially comprises three parts. These parts are the first region (331); the intermediate region (332) and the second region (333). The part of the hole (33) which is adjacent to the control volume (32) is defined as said first region (331). The hole (33) has a circular cross section in this region. There is said intermediate region (332) at the continuation of the first region (331). The intermediate region (332) exists in the opposite direction of the first region (331) in X direction. The diameter of the intermediate region (332) is embodied to be smaller than the diameter of the first region (331). There is said second region (333) at the continuation of the intermediate region (332). The diameter of the second region (333) is embodied to be greater than the diameter of the intermediate region (332) and embodied to be smaller than the diameter of the first region (331). The second region (333) ends so as to be adjacent to the fourth angled edge (344) and to the armature (40). There is a circularly embodied seating edge (345) between the fourth angled edge (344) and the second region (333). Said seating edge (345) is embodied in a convex manner so as to have a certain diameter. The valve piece (30) seats onto the seating surface (422) of the armature (40) by means of the seating edge (345). The region, which is provided by means of the seating edge (345) and which remains between the armature (40) and the second region (333) is defined as the space (21). The region, which is provided by means of the angled edges (341, 342, 343, 344) existing on the valve piece (30) and which is provided between the valve piece (30) and the armature (40), is defined as the valve bearing (14). Moreover, the region, where the seating edge (345) of the valve piece (30) and the seating surface (422) of the armature (40) contact with each other, is defined as the seating region (20). In said seating region (20), the sealing and tightness between the armature (40) and the valve piece (30) is provided by linear contact.

Injection valves (10) are essentially used for spraying fuel to the combustion chamber in internal combustion engines. The fuel enters into the injection valves (10) through the input region (11) and the fuel is transferred to the needle region (12) by means of the different members (not illustrated in the figure) and the spraying process is realized by the members (not illustrated in the figure) in the needle region (12). The valve piece (30) separates the high and low pressure regions inside the injection valve (10) from each other and it provides the sealing between these regions. The control volume (32) facilitates the transfer of the fuel to the needle region (12) in a controlled manner. The armature (40) covers the hole (33) of the valve piece (30) with the help of electrical systems (not illustrated in the figure) and prevents fuel discharge up to a certain pressure through the valve piece (30). In case the level of the fuel, existing inside the control volume (32), exceeds a certain level, the force formed by the fuel to the armature (40) overcomes the closing force of the armature (40) and thereby the fuel is discharged from the control volume (32) to the valve bearing (14).

Inside the injection valve (10), cavitation bubbles are formed in the high pressured fuel particularly in cases of overloads to the engine. The cavitation bubbles existing inside the fuel, which passes from the control volume (32) to the valve bearing (30) by means of the hole (33), blow out inside the hole (33), and in the passages of said bubbles to the region where the valve bearing (14) exists, they do not lead to any abrasion or cavitation on the outer face of the valve piece (14). Moreover, inside the fuel, after the cavitation bubbles which are not blown out inside the hole (33) pass to the valve bearing (14) part, thanks to the flow precautions which are created by the angled edges (341, 342, 343, 344) of the valve piece (30), the bubbles, which have not blown out, blow out before they approach the valve piece (30) and they do not give damage to the members (not illustrated in the figure) of the injection valve (10) which are adjacent to the valve bearing (14).

The hole (33), which is embodied so as to be longer when compared with the prior art, and particularly the second region (333) helps the cavitation bubbles to blow out inside the hole (33). Thanks to this, the valve bearing (14) is protected from cavitation during high engine loadings. Moreover, thanks to the angled edges (341, 342, 343, 344) corresponding to the valve bearing (14) part on the valve piece (30) and thanks to the convex surfaces, the cavitation bubbles reaching the valve bearing (14) part blow out before approaching the valve piece (30) and the cavitation problem is prevented. Problems may occur since the tightness, existing in the seating region (20) wherein seating is realized between the valve piece (30) and the armature (40), is provided by linear contact. These problems are the abrasion in the adhesive and material fatigue, which occur under high operation temperatures. In order to prevent these problems formed since the material hardness of the valve piece (30) and of the armature (40) is different, the narrow region (42) of the armature (40) is subject to hardening process using approximately 30 % nitrogen and the hardness of different materials which are in contact with each other is equalized. Moreover, as the length of the hole (33) existing on the valve piece (30) is increased, the control volume (32) also increases and this increase in the control volume (32) is compensated by decreasing the course length (not illustrated in the figure) of the injector needle (not illustrated in the figure), and the operation conditions of the injection valve (10) are preserved.

The protection scope of the present invention is set forth in the annexed Claims and cannot be restricted to the illustrative disclosures given above, under the detailed description. It is because a person skilled in the relevant art can obviously produce similar embodiments under the light of the foregoing disclosures, without departing from the main scope of the present invention, as defined in the appended claims.

Claims

An injection valve (10) comprising an input region (11) through which the fuel enters; an armature (40) having a wide region (41) which is provided at the continuation of said input region (11) and having a narrow region (42) with a seating surface (422) at the continuation thereof; a valve piece (30) which has a seating part (34) and which is provided at the continuation of said armature (40) and which is positioned so as to define a valve bearing (14) in between; a control volume (32) provided inside said valve piece (30); and a hole (33) which is provided at said valve piece (30) between said valve bearing (14) and said control volume (32), comprising at least one seating region (20) where the fuel, exiting from said hole (33) towards the valve bearing (14), is sealed; a sealing surface (345, 422), which has a linear cross section, the part of which at least covers the hole (33) between the armature (40) and the valve piece (30) in said seating region (20); and cut-outs on the valve piece (30) and on the armature (40) so that the fuel, comprising cavitation bubbles and exiting the hole (33), is able to flow substantially far away from the edges of the armature (40) and of the valve piece (30) inside the valve bearing (14), and there is at least one seating edge (345) between the seating region (20) and the end of the hole (33) at a vicinity of the seating region (20).
An injection valve (10) according to Claim 1, characterized in that the passage from said wide region (41), provided at the armature (40), to said narrow region (42) comprises at least one inclined edge (421); the valve piece (30) comprises angled edges (341, 342, 343, 344) with respect to each other in order to provide the free spreading of the fuel, exiting the hole (33) of the seating region (20), in the valve bearing (14); and there is at least one passage edge (347) which is embodied at the lower elevation at a certain distance in X direction from the point where the hole (33) is opened into the valve bearing (14).
An injection valve (10) according to Claim 1, characterized in that said seating edge (345) is curved.
An injection valve (10) according to Claim 2, characterized in that the passage from said wide region (41), provided at the armature (40), to said narrow region (42) comprises at least one inclined edge (421) which is positioned in X direction and at a certain angle to said flat edge (411); at least one seating surface (422) which is provided at the continuation of said inclined edge (421) and which is positioned substantially parallel to the flat edge (411); at least one passage edge (347) which is positioned substantially parallel to the flat edge (411) and which is provided at the continuation of said second angled edge (342) of said seating part (34) which is provided at the valve piece (30); at least 5 one third angled edge (343) which is provided at the continuation of said passage edge (347) and which is positioned in opposite direction to the X direction and so as to make a certain angle with the passage edge (347); at least one fourth angled edge (344) which is provided at the continuation of said third angled edge (343) and which is positioned so as to make a certain angle with the third angled edge (343); and at least one seating edge (345) which is provided between said fourth angled edge (344) and said hole (33) and where the valve piece (30) is in linear contact with the armature (40).