EP1296054B1 - Injection valve for a combustion engine - Google Patents

Description

State of the art

The invention relates to an injection valve with the features of the preamble of claim 1.

Such injection valve is known from DE 198 32 826 A1 known. The injection valve shown there is as an injector trained and used in a common rail injection system used for internal combustion engines, which is a high-pressure fuel storage having, with a high pressure pump in Connection stands. The injection valve has a with the High-pressure fuel storage connected high-pressure fuel outlet, a low-pressure fuel port for connection to a fuel return device and an electrical Connection on, which for electrical control of a electrically actuatable control valve of the injection valve, For example, a solenoid valve is used. In the known Injection valve is a valve needle via a valve piston of prevailing in a control pressure chamber fuel pressure loaded in the closing direction. The control pressure chamber is arranged in a valve piece inserted into the valve housing and via an inlet channel provided with an inlet throttle and a drain channel provided with an outlet throttle with the high-pressure fuel connection, respectively connected to the fuel low pressure port. With a Valve member of a control valve, which as a drive, for example having a magnetic actuator or a piezo actuator, the drainage channel can be closed and opened and the fuel pressure in the control pressure chamber for the individual Actuating operations of the valve needle can be controlled. The Opening speed of the valve needle is opened Drain channel through the flow difference between inlet throttle and drain throttle and thus ultimately through the fixed set size ratio of inlet and outlet throttle certainly.

In the known injection valve, the inlet channel for High-pressure fuel formed in several parts and includes a introduced into a valve housing part of the injection valve Inlet bore, which in a surrounding the valve piece Annular space in an inner recess of the valve housing part opens. The inlet bore discharges with its entire Inner cross section in the inner recess. In practice has been shown that in the intersection of inlet bore and inner recess due to the high fuel pressure and the notch effect of inlet hole strong Tensile stresses occur in the circumferential direction, resulting in fractures and can cause cracking.

Advantages of the invention

The injection valve according to the invention with the Features of claim 1 has the advantage that the notch stresses in the intersection between the inner recess and the access hole are significantly reduced and thereby the strength of the injector is greatly increased. at the injection valve according to the invention cuts the inlet bore the inner recess of the valve housing part of the injection valve only with a part of its inner cross section. Reduce by changing the shape of the transition edge advantageous in the case of a high pressure in the circumferential direction acting material stresses. Without much extra effort in the production can so the life and reliability of the injectors are increased.

According to a further characterizing feature of claim 1 is the Inlet bore from a connection of the valve body part so far into the Valve housing part introduced that the inlet bore on the inner recess extends into the remote from the terminal part of the valve body part. As a result, a symmetrical shape of the transition edge of the inlet bore and inner recess, whereby the notch stresses reduced particularly strong become.

From DE 198 59 592 C1 is a fuel injection valve for a high-pressure injection of fuel from a central high-pressure accumulator into combustion chambers of a Internal combustion engine known. The high-pressure accumulator is above a Inlet throttle bore with a control chamber, which opens and closes a Injector controls, in operative connection. The inlet throttle bore is opposite to the Control room aligned eccentrically.

Advantageous embodiments and further developments of the invention are characterized by the in allows the features contained in the dependent claims.

It is particularly advantageous to extend beyond the inner recess Part of the inlet bore to connect to a supply bore, which with the Injection opening of the injection valve is in communication. About the inlet hole is Thus advantageous both the inner part of the valve surrounding the recess Valve housing part as well as connected to the injection port Supply bore supplied with high pressure fuel, so that the construction of the Injector can be simplified. Since no further drilling of the High pressure connection go out, coming from the high-pressure fuel storage Connecting line are screwed directly onto the valve body part and, for example the fuel filter are integrated into the valve housing part.

It is particularly advantageous for the transition edge between the at least one Inlet hole and the inner recess to round off the valve housing part. The rounding of the edge structure caused by the changed shape of the Transition edge improved high pressure resistance in the intersection area. Furthermore, it is advantageous that the transition edge during electrochemical or other processes, where a material processing tool in the Inner recess of the valve body part is introduced, in Compared to the prior art shaped differently and better is accessible.

drawings

Fig. 1a einen Querschnitt durch den oberen Teil eines aus dem Stand der Technik bekannten Einspritzventils,

Fig. 1b den unteren Teil des Einspritzventils aus Fig. 1a,

Fig. 2 einen vereinfachten Querschnitt durch ein Gehäuseteil des erfindungsgemäßen Einspritzventils längs der Linie II-II in Fig. 3,

Fig. 3 einen weiteren Querschnitt durch das erfindungsgemäße Einspritzventil,

Fig. 4 einen vergrößerten Teilquerschnitt durch das Einspritzventil senkrecht zur Zugangsbohrung.

Embodiments of the invention are illustrated in the drawings and will be explained in the following description. It shows

1a shows a cross section through the upper part of an injection valve known from the prior art,

1b shows the lower part of the injection valve of Fig. 1a,

2 shows a simplified cross section through a housing part of the injection valve according to the invention along the line II-II in Fig. 3,

3 shows a further cross section through the injection valve according to the invention,

Fig. 4 is an enlarged partial cross section through the injection valve perpendicular to the access hole.

Description of an embodiment

Figures 1a and 1b show one known from the prior art Fuel injection valve 1, which for use in a fuel injection system is determined with a High-pressure fuel storage is equipped by a High pressure pump continuously with high pressure fuel is supplied. The illustrated fuel injection valve 1 has a valve housing part 4 with an inner recess 20th on, which forms a longitudinal bore 5 on a part of its length, in which a valve piston 6 is arranged, with his an end to a arranged in a nozzle body 65 Valve needle 60 acts. The valve needle 60 is in one Pressure chamber 61 is arranged, which via a supply bore. 8 supplied with high-pressure fuel. At a Opening stroke of the valve piston 6 is the valve needle 60 by constantly on a pressure shoulder 68 of the valve needle counteracting fuel high pressure in the pressure chamber the closing force of a spring 63 is raised. By then with the injection chamber 7 connected to the pressure chamber, the injection takes place of the fuel into the combustion chamber of the internal combustion engine. By lowering the valve piston 6, the valve needle in the closing direction in the valve seat 62 of the injection valve pressed and the injection process ended.

As can be seen in Fig. 1a, the valve piston 6 is on his facing away from the valve needle end in a cylinder bore 11 out, which introduced into a valve piece 12 which is in a longitudinal bore 5 continuing coaxial Hole 15 is inserted with a wider diameter. The Valve piece 12 is fixed in a flange portion 22 via a Screw member 23 braced with the valve housing part 4. The Inner recess 20 of the valve housing part 4 also has an adjoining the bore 15 further bore with an even wider diameter, so that between the outer jacket of the valve member 12 and the cylindrical Inner wall 35 of the further bore an annular space in the inner recess 20 is created. In the cylinder bore 11 of Valve piece closes an end face 13 of the valve piston. 6 a control pressure chamber 14, which via an inlet channel with a high-pressure fuel port 3 is connected. The inlet channel is formed essentially in three parts. A radially through the wall of the valve member 12 leading bore 26, whose inner walls on a part of its length an inlet throttle form, is with the valve piece 12 circumferentially surrounding annulus constantly connected, which annulus sealed by a sealing ring 39 to the longitudinal bore 5 is and via an inlet bore 16 and a fuel filter 42 in constant communication with the high-pressure fuel connection 3 of a screwed into the valve housing part 4 Connecting piece 9 is. The inlet bore 16 opens at the known in the art injectors with their entire inner cross section in the inner recess 20 of the Valve housing part 4 a. Via the inlet channel with inlet throttle is the control pressure chamber 14 in the high-pressure fuel storage exposed to high fuel pressure. Coaxial to the valve piston 6 branches from the control pressure chamber fourteenth continue from a running in the valve piece 12 bore, the a provided with an outlet throttle 18 fuel drain passage 17 forms, which opens into a discharge space 19, which is connected to a fuel low-pressure connection 10 is, which in turn in a manner not shown connected to a fuel return. The exit the fuel drain passage 17 is made from the valve piece 12 in the region of a conically countersunk part 21 of the outer End face of the valve piece 12. In the conical Part 21 is a valve seat 24 is formed with the a control valve member 25 of the injection valve controlling Solenoid valve 30 cooperates. The control valve member 25th is coupled to an armature 27, which armature with a Solenoid of the solenoid valve 30 cooperates. The anchor 27 and the armature coupled to the control valve member 25th are constantly supported by a housing fixed Closing spring 31 is acted upon in the closing direction, so that the Control valve member 25 normally in the closed position on Valve seat 24 is present. Upon excitation of the electromagnet is the armature 27 moves towards the electromagnet, whereby the drainage channel 17 is opened to the discharge space 19 out.

The opening and closing of the injector will be as follows described controlled by the solenoid valve 30. Of the Anchor 27 is constantly closed by the closing spring 31 in the closing direction acted upon, so that the control valve member 25 at non-energized electromagnet in the closed position on the valve seat 24 is applied and the control pressure chamber 14 to the discharge side 19 is closed, so that there over the inlet channel very fast the high pressure builds up, which also in the Fuel high pressure accumulator is pending. About the area of Front side 13 generates the pressure in the control pressure chamber 14 a Closing force on the valve piston 6 and the associated standing valve needle 60, which is larger than the other in the opening direction due to the upcoming high pressure acting forces. If the control pressure chamber 14 through Opening the solenoid valve to the discharge side 19 out, the pressure builds up in the small volume of the control pressure chamber 14 very fast, as this over the inlet throttle is decoupled from the high pressure side. Consequently outweighs the valve needle in the opening direction acting force from the pending on the valve needle fuel high pressure, so that the valve needle 60 moves upward and at least one injection opening 7 for injection is opened. However, closes the solenoid valve 30th the fuel drain passage 17, the pressure in the control pressure chamber 14 through the nachfließenden over the inlet channel fuel be rebuilt so that the original Closing force is present and the valve needle of the fuel injection valve closes.

Fig. 2 and Fig. 3 each show a cross section through the injection valve according to the invention. Same reference numbers as in Fig. 1a and 1b mean the same parts. In Fig. 2 is the upper part of the valve housing part 4 is shown, the through-going Inner recess 20 through the longitudinal bore 5 and the coaxially adjoining bores 15 and 35 formed becomes. The holes 15 and 35 serve to receive the Valve piece 12, wherein the outer shell of the valve piece with the inner wall of the bore 35 forms an annular space. Of the High pressure port 3 is formed on a nozzle 9, which For example, by forging integrally with the valve housing part 4 is connected. The high pressure connection 3 has a receiving bore 33 for a fuel filter on, from which mounting hole out of an access hole 16 extends into the valve housing part 4. The access hole 16 intersects the inner recess 20 of the valve housing part 4 only with a part of its inner cross section 44, as best seen in FIGS. 3 and 4. The Access hole 16 intersects the inner recess 20 in the area the cylinder jacket-shaped wall 35 only with the part 45th its inner cross section 44, but not with the part 46 of the Inner cross section 44. This changes the shape of the Transition edge 38 between the inlet bore 16 and the inner wall 35 of the inner recess 20 to an elongated, narrow contour. If "r" is the radius of the access hole 16 is, "R" the radius of the cylinder jacket-shaped inner wall 35 of the inner recess 20 and "d" the distance of the central axis 50 of the access hole 16 from the central axis 51 of the inner recess 20, this is achieved if the following both geometric conditions are met simultaneously: 1) r + d> R and 2) d - r <R.

In the embodiment shown in Fig. 4, the distance d the central axis 50 of the access hole 16 of the Central axis 51 of the inner recess 20 equal to the radius R. the inner recess 20 in the region of the cylinder jacket-shaped Inner wall 35. The distance d can also be larger or smaller be as the radius R of the inner recess 20. Important is that the access hole, the inner recess only with a portion of its inner cross section 44 cuts.

As best seen in Fig. 3, the access hole is 16 of the receptacle 33 of the high pressure port 3 from so far introduced into the tubular body 1, that with a section 36 a little way over the inner recess 20 also in the of the high pressure port. 3 remote from the valve body part 4 extends where it is connected to the supply bore 8. In this one the embodiment shown, the access hole is the end connected to the supply hole. The supply hole 8 can also be T-shaped from the section 36 of Branch off access hole 16. The from the high-pressure fuel connection 3 outgoing access hole 16 thus supplies Advantageously, the inner recess 20 and the supply bore 8 with high pressure fuel.

Although the central axis 50 of the access hole 16 in the here shown preferred embodiment perpendicular to the central axis 51 of the inner recess 20 of the valve body part. 4 runs, it is also possible that the central axis 50 of the Access hole 16 at an angle other than 90 ° extends to the central axis 51 of the inner recess.

To the strength of the transition edge 38 in the intersection area the inner wall 35 and the access hole 16 to increase it is advantageous to round the transition edge 38 and thereby deburring what, for example, in an electrochemical Procedure can be done where a material removal Workpiece inserted into the inner recess 20 becomes. Due to the good accessibility of the transition edge 38 larger fillets can be made, resulting in again positive for the strength of the injection valve in the Intersection of inner recess and inlet bore effect.

The invention presented here is by no means to injection valves limited for common rail systems and can applied to all injectors for internal combustion engines where there is an access hole for high pressure fuel with an inner recess of the valve body part communicates. Due to the fact that the inner recess of the inlet hole is only cut and the access hole does not completely open into the inner recess, the structure of the transition edge changes advantageously such that notch stresses are reduced and the high pressure resistance of the injection valve is increased.

Claims (5)

1. Injection valve for an internal combustion engine, in particular injection valve for a common rail fuel injection system, comprising a valve-housing part (4) with an inner recess (20) having a substantially circular cross section, and comprising an inlet hole (16) for high-pressure fuel, the said inlet hole (16) opening into the inner recess (20), characterized in that the inlet hole (16) intersects with the inner recess (20) of the valve-housing part (4) only with a part (45) of its inner cross section (44), and the inlet hole (16), starting from a connection (3) of the valve-housing part (4), is made in the valve-housing part (4) to such an extent that the inlet hole (16) extends beyond the inner recess (20) into that part of the valve-housing part (4) which faces away from the connection (3).
2. Injection valve according to Claim 1, characterized in that a section (36) of the inlet hole (16) is connected to a supply hole (8) which is connected to an injection opening (7) of the injection valve, which section (36) extends beyond the inner recess (20) into that part of the valve-housing part (4) which faces away from the connection (3).
3. Injection valve according to one of the preceding claims, characterized in that the transition edge (38) between the at least one inlet hole (16) and the inner recess (20) of the valve-housing part (4) is rounded.
4. Injection valve according to one of the preceding claims, characterized in that a part of the inner cross section (44) of the inlet hole (16) intersects with the inner recess (20) of the valve-housing part (4) in the region of an inner wall (35) of the inner recess (20), which inner wall (35) is in the shape of a lateral wall of a cylinder.
5. Injection valve according to one of the preceding claims, characterized in that the centre axis (50) of the inlet hole (16) extends perpendicularly with respect to the centre axis (51) of the inner recess (20).

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