JP4184741B2 - Injection valve for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an injection valve for an internal combustion engine, particularly an injection valve for a common rail fuel injection system, which has a valve casing portion having an inner notch having a substantially circular cross section, and opens into the inner notch. The present invention relates to a type in which an inflow hole for high-pressure fuel is provided.
[0002]
[Prior art]
An injection valve of this type is known from German Offenlegungsschrift DE 19283826. This known injection valve is used in a common rail injection device for an internal combustion engine, which is formed as an injector and has a high-pressure fuel accumulator connected to a high-pressure pump. The injection valve has a fuel high pressure connection connected to the fuel high pressure accumulator, a fuel low pressure connection for connection to the fuel return device, and an electrical connection. Serves to electrically control an electrically actuated control valve of an injection valve, for example an electromagnetic valve. In known injection valves, the valve needle is loaded in the closing direction by the fuel pressure in the control pressure chamber via the valve piston. The control pressure chamber is arranged in a valve member inserted in the valve casing and is connected to the fuel high pressure connection or the fuel low pressure connection via a supply passage with a supply throttle and a discharge passage with a discharge throttle. Connected to the department. The discharge passage can be opened and closed by a valve component of the control valve, for example having an electromagnetic adjustment device or a piezoelectric adjustment device as the drive device, and the fuel pressure in the control pressure chamber is controlled by the individual operation of the valve needle. Can be controlled for the process. The opening speed of the valve needle is defined by the through-flow difference between the supply throttle and the discharge throttle when the discharge passage is opened, and thus the dimension ratio adjusted to the immobility between the supply throttle and the discharge throttle.
[0003]
In the known injection valve, the supply passage for the high-pressure fuel is formed from a plurality of parts, and has an inflow hole provided in the valve casing part of the injection valve, and this inflow hole is formed inside the valve casing part. In the notch, it opens to the ring chamber surrounding the valve member. In this case, the inflow hole is open to the internal notch in its entire internal cross section. The following is known in the field. That is, in the known injection valve, a strong tensile stress is generated in the circumferential direction based on the notch effect of the inflow hole and high fuel pressure in the intersection region between the inflow hole and the internal notch. Otherwise, damage or crack formation may occur.
[0004]
[Patent Document 1]
German Federal Republic of Patent Publication No. 1882826 Specification
[Problems to be solved by the invention]
Therefore, the object of the present invention is to improve the injection valve of the type described at the beginning, and to reliably avoid generation of strong tensile stress in the intersecting region between the inflow hole and the internal notch, and thus breakage and crack formation in the region. It is to provide an injection valve.
[0006]
[Means for Solving the Problems]
In order to solve this problem, in the configuration of the present invention, the inflow hole intersects with the internal notch of the valve casing part and only a part of the internal cross section.
[0007]
【The invention's effect】
The injection valve according to the present invention configured as described above has the following advantages. That is, in the injection valve according to the present invention, the notch stress in the crossing region between the internal notch and the inflow hole is remarkably reduced, thereby significantly increasing the strength of the injection valve. In the injection valve according to the invention, the inflow hole only intersects with an internal notch in the valve casing part of the injection valve at a part of its internal cross section. By changing the shape of the transition edge, the material stress acting in the circumferential direction during high pressure loads is advantageously reduced. In this way, the useful life and certainty of the injection valve can be increased without significant effort or expense during manufacture.
[0008]
Another advantageous configuration of the invention is described in the subclaims.
[0009]
In an advantageous configuration of the invention, the inflow hole is provided in the valve casing part from the connection part of the valve casing part, and the part of the valve casing part opposite to the connection part passes through the internal notch. It extends to. If comprised in this way, the transition edge part from an inflow hole to an internal notch can be symmetrically provided, and notch stress can be reduced especially strongly by this.
[0010]
In a particularly advantageous configuration of the invention, the inflow hole is connected to the supply hole in a section extending beyond the internal notch, which supply hole is connected to the injection opening of the injection valve. If comprised in this way, a high pressure fuel can be advantageously supplied to the internal notch which surrounds the valve member of a valve casing part, and the supply hole connected to the injection opening via an inflow hole. Therefore, the configuration of the injection valve can be simplified. Since no other holes extend from the high-pressure connection, the connection conduit extending from the fuel high-pressure accumulator can be screwed directly to the valve casing part and, for example, a fuel filter is integrated into the valve casing part. Can do.
[0011]
In a particularly advantageous configuration of the invention, the transition edge between the at least one inlet hole and the internal notch of the valve casing part is rounded and chamfered. By forming a rounded portion at the edge and changing the shape of the transition edge, improved high pressure strength is obtained in the intersection region. In yet another advantage, during the electrochemical or other method of introducing a material processing tool into the internal notch of the valve body portion, the transition edge is shaped differently than in the prior art, And good accessibility.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0013]
1a and 1b show a known fuel injection valve 1 based on the prior art, which comprises a high-pressure fuel accumulator to which high-pressure fuel is continuously supplied by a high-pressure feed pump. It is used in a fuel injection device. The illustrated fuel injection valve 1 has a valve casing part 4 provided with an internal notch 20, which has a longitudinal hole 5 formed in a part of its entire length. A valve piston 6 is disposed in the hole 5, and one end of the valve piston 6 acts on a valve needle 60 disposed in the nozzle body 65. The valve needle 60 is disposed in the pressure chamber 61, and fuel under high pressure is supplied to the pressure chamber 61 through the supply hole 8. During the opening stroke of the valve piston 6, the valve needle 60 is lifted against the closing force of the spring 63 by the high fuel pressure in the pressure chamber that always acts on the pressure shoulder 68 of the valve needle. The fuel is injected into the combustion chamber of the internal combustion engine through the injection opening 7 connected to the pressure chamber. As the valve piston 6 moves down, the valve needle is pushed into the valve seat 62 of the injection valve in the closing direction, and the injection process ends.
[0014]
As can be seen from FIG. 1 a, the valve piston 6 is guided in a cylindrical hole 11 at the end opposite to the valve needle, and this cylindrical hole 11 is provided in the valve member 12. The longitudinal hole 5 is extended and inserted into a coaxial hole 15 having a large diameter. The valve member 12 is firmly fastened to the valve casing part 4 via a screw member 23 in the flange region 22. The inner notch 20 of the valve casing part 4 further has another term connected to the hole 15 and having a larger diameter, so that the outer peripheral wall of the valve member 12 and the cylindrical inner wall of another hole In between, a ring chamber is formed in the inner notch 20. In the cylindrical hole 11 of the valve member, the end face 13 of the valve piston 6 closes the control pressure chamber 14, and the control pressure chamber 14 is connected to the fuel high-pressure connection 3 via the supply passage. The supply passage is formed of approximately three parts. The hole 26 extending radially through the wall of the valve member 12 has a supply restrictor formed in the inner wall in a part of its entire length, and always has a ring chamber surrounding the entire circumference of the valve member 12. The ring chamber is connected to the longitudinal bore 5 via a seal ring 39 and is connected to the valve casing part 4 via a supply restrictor 16 and a fuel filter 42. 9 is always connected to the fuel high pressure connection 3. In the injection valve known in the prior art, the inflow hole 16 opens into the inner notch 20 of the valve casing part 4 over the entire internal cross section. The control pressure chamber 14 is exposed to high fuel pressure in the fuel high-pressure accumulator through a supply passage provided with a supply throttle. A hole extending in the valve member 12 is branched from the control pressure chamber 14 coaxially with the valve piston 6, and this hole forms a fuel discharge passage 17 having a discharge throttle 18. The fuel discharge passage 17 is open to a pressure release chamber 19 which is connected to a fuel low pressure connection 10 which further returns the fuel in a manner not shown. Connected to the road. Outflow of the fuel discharge passage 17 from the valve member 12 is performed in the region of the conical concave portion 21 on the end surface located outside the valve member 12. A valve seat 24 is formed in the conical portion 21, and a control valve member 25 of an electromagnetic valve 30 that controls the injection valve cooperates with the valve seat 24. The control valve member 25 is connected to a mover 27, and the mover 27 cooperates with the electromagnet of the electromagnetic valve 30. Since the movable element 27 and the control valve member 25 connected to the movable element are always loaded in the closing direction by a closing spring 31 that is immovably supported with respect to the casing, the control valve member 25 is normally closed. It contacts the valve seat 24 in the position. When the electromagnet is excited, the mover 27 is moved toward the electromagnet, whereby the discharge passage 17 is opened toward the pressure release chamber 19.
[0015]
The opening and closing of the injection valve is controlled by the electromagnetic valve 30 as described below. Since the movable element 27 is always loaded in the closing direction by the closing spring 31, the control valve member 25 is in contact with the valve seat 24 in the closed position when the electromagnet is not excited, and the control pressure chamber 14 is released. Closed to the pressure side 19. As a result, a high pressure is formed very quickly there via the supply passage, which is also present in the fuel high-pressure accumulator. Due to the area of the end face 13, the pressure in the control pressure chamber 14 causes a closing force on the valve piston 6, and thus on the valve needle 60 coupled thereto, which is caused by the high pressure present on the other side. It is greater than the force acting in the opening direction. When the control pressure chamber 14 is opened toward the pressure release side 19 by opening the electromagnetic valve, the pressure in the small volume of the control pressure chamber 14 drops very quickly. This is because the control pressure chamber 14 is blocked from the high pressure side via the supply throttle. As a result, a force acting in the opening direction on the valve needle based on the high fuel pressure in the valve needle dominates, so that the valve needle 60 is moved towards information and at least one injection opening 7 is for injection. Released. However, when the solenoid valve 30 closes the fuel discharge passage 17, the pressure in the control pressure chamber 14 can be increased again by the fuel replenished through the supply passage, so that the original closing force is generated and the fuel injection valve is generated. The valve needle closes the injection opening.
[0016]
2 and 3 each show a sectional view of an injection valve according to the present invention. The same symbols are used for the same members as in FIGS. 1a and 1b. FIG. 2 shows the upper part of the valve casing part 4, and an internal notch 20 passing through the casing part 4 is provided with a longitudinal hole 5, a hole 15 connected coaxially to the longitudinal hole 5, 35. The holes 15, 35 serve to receive the valve member 12, in which case the outer peripheral wall of the valve member forms a ring chamber together with the inner peripheral wall of the hole 35. The high-pressure connecting part 3 is formed in a pipe piece 9, and this pipe piece 9 is integrally coupled to the valve casing part 4 by forging, for example. The high-pressure connection 3 has a receiving hole 33 for the fuel filter, from which an inflow hole 16 extends through the valve casing part 4. As best seen in FIGS. 3 and 4, the inflow hole 16 crosses the internal notch 20 of the valve casing portion 4 only at a portion of its internal cross section 44. The inflow hole 16 crosses the inner notch 20 in the region of the cylindrical peripheral wall 35 only at a part of the inner cross section 44, that is, the part 45, and does not cross the part 46 of the inner cross section 44. As a result, the shape of the transition edge 38 between the inflow hole 16 and the inner wall 35 of the internal notch 20 changes to a vertically long thin outline. “R” is the radius of the inflow hole 16, “R” is the radius of the cylindrical inner wall 35 of the inner notch 20, and “d” is the center axis 50 of the inflow hole 16 and the center axis of the inner notch 20. This is obtained if the following two geometrical conditions are met simultaneously:
1) r + d> R and 2) d−r <R
In the embodiment shown in FIG. 4, the distance d between the center axis 50 of the inflow hole 16 and the center axis 51 of the inner notch 20 is the radius R of the inner notch 20 in the region of the cylindrical inner wall 35. be equivalent to. The distance d can however also be larger or smaller than the radius R of the inner notch 20. What is important is that the inflow hole simply crosses the internal notch at a portion of its internal cross section 44.
[0017]
As can be seen best from FIG. 3, the inflow hole 16 enters the tubular base body 1 from the receiving portion 33 of the high-pressure connection 3 as follows. That is, in this case, the inflow hole 16 is a section 36 and extends in the section of the valve body portion 4 on the side opposite to the high pressure connection portion 3 to some extent beyond the internal notch 20, where the inflow hole 16 or the section 36 thereof is , Connected to the supply hole 8. In the illustrated embodiment, the inlet hole is connected to the supply hole at the end. However, the supply hole 8 may also branch off from the section 36 of the inflow hole 16 in a T-shape. An inflow hole 16 extending from the high-pressure fuel connection 3 supplies the high-pressure fuel to the internal notch 20 and the supply hole 8 in an advantageous manner thereby.
[0018]
In the preferred embodiment shown, the central axis 50 of the inflow hole 16 extends perpendicular to the central axis 51 of the internal notch 20 of the valve body part 4, however, the central axis 50 of the inflow hole 16 is also internal. A configuration is also possible in which the center axis 51 of the notch 20 extends at an angle different from 90 °.
[0019]
In order to increase the strength of the transition edge 38 in the region of intersection of the inner wall 35 and the inlet hole 16, it is advantageous to round and chamfer the transition edge 38 and deburr it. Such processing can be performed, for example, in an electrochemical method, in which a tool for removing material is introduced into the internal notch 20. Based on the good accessibility to the transition edge 38, a relatively large rounding can be formed, which is positive for the strength of the injection valve at the intersection of the internal notch and the inlet. Act on.
[0020]
The present invention is not limited to an injection valve for a common rail system, and is used in all injection valves for an internal combustion engine in which an inflow hole for high-pressure fuel is connected to an internal notch of a valve body portion. Can do. The internal notch of the inflow hole is simply cut out, and the inflow hole is not completely open to the internal notch, thereby advantageously changing the structure of the transition edge and reducing the notch stress. The high pressure strength of the injection valve can be increased.
[Brief description of the drawings]
FIG. 1a is a cross-sectional view showing the upper part of a known injection valve according to the prior art.
FIG. 1b is a cross-sectional view showing a lower portion of the injection valve shown in FIG. 1a.
2 is a cross-sectional view taken along the line II-II in FIG. 3 of the casing portion of the injection valve according to the present invention.
FIG. 3 is another cross-sectional view showing a casing portion of an injection valve according to the present invention.
FIG. 4 is a cross-sectional view of an injection valve according to the present invention perpendicular to an inflow hole.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel injection valve, 3 High pressure connection part, 4 Valve casing part, 5 Longitudinal hole, 6 Valve piston, 7 Injection opening, 8 Supply hole, 9 Connection pipe piece, 10 Fuel low pressure connection part, 11 Cylindrical hole, 12 Valve member , 13 end face, 14 control pressure chamber, 15 holes, 16 supply throttle or inflow hole, 17 fuel discharge passage, 18 discharge throttle, 19 pressure release chamber, 20 internal notch, 21 part, 22 flange area, 23 screw member, 24 Valve seat, 25 control valve member, 26 holes, 27 mover, 30 solenoid valve, 31 closing spring, 35 holes, 36 section, 38 transition edge, 42 fuel filter, 44 internal cross section, 45, 46 part, 60 valve Needle, 61 Pressure chamber, 62 Valve seat, 63 Spring, 65 Nozzle body, 68 Pressure shoulder

Claims (4)

An injection valve for an internal combustion engine, comprising a valve casing part (4) with an internal notch (20) having a substantially circular cross section, and an inflow for high pressure fuel opening into the internal notch (20) In the type in which the hole (16) is provided, the inflow hole (16) intersects with the internal notch (20) of the valve casing part only at a part (45) of the internal cross section (44). And the inflow hole (16) is provided in the valve casing part from the connection part (3) of the valve casing part (4), and the inflow hole (16) extends beyond the internal notch (20) to the valve casing part ( 4) extends to the opposite side of the connecting part (3), and the inflow hole (16) extends beyond the inner notch (20) to the connecting part (3) of the valve casing part (4). ) In a section (36) extending to the opposite side of the supply hole (8) Be connected with, characterized in that the feed hole (8) is connected to the injection opening of the injection valve (7), the injection valve for an internal combustion engine. At least transition edge between the-out internal notches (20) of one inlet hole (16) and the valve casing part (4) (38) are rounded, claim 1 injection valve according. The inflow hole (16) is a part of its internal cross section (44) and intersects in the region of the internal notch (20) of the valve casing part and the cylindrical peripheral wall-like inner wall (35) of the internal notch (20). The injection valve according to claim 1 or 2 . The central axis (50) is-out internal notches (20) central axis (51) extends perpendicularly to the injection valve of any one of claims 1 to 3 for the inlet (16).

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