JP5723671B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve for an automobile internal combustion engine.

  In order to improve the oil tightness of the sheet, it is generally required to perform ultra-precise machining of the contact surfaces of the two members that form the sheet part, and it is necessary to finish the surface roughness to the very best state. Will increase. Moreover, in order not to increase the sheet part processing accuracy more than necessary, a method such as devising the shape of the sheet part (Patent Document 1) may be taken.

  In a direct injection type engine in which fuel is directly injected into the combustion chamber, the fuel injection valve is not operated in a closed state except for the injection timing normally controlled by the engine control unit (this is referred to as a non-operation period). However, since the fuel pressure inside the fuel injection valve remains high during the non-operation period, the fuel leaks into the combustion chamber if the oil tightness of the seat portion is poor. Therefore, improvement of the oil tightness performance in the seat portion of the fuel injection valve is required.

  Therefore, in the fuel injection valve described in Patent Document 1, a protruding portion is formed on either the abutting portion or the valve seat of the valve member, and the protruding portion is formed by repeatedly seating the abutting portion on the valve seat. To improve the oil-tight performance.

JP 2001-12330 A

  In the structure of Patent Document 1, it is considered that the stroke performance of the valve member is deteriorated with time because the contact portion of the valve member or the protrusion formed on the valve seat is positively deformed. The stroke of the valve member directly affects the injection amount characteristic which is the basic performance of the fuel injection valve. Since the injection quantity characteristic is closely related to engine control, a change in the stroke of the valve member causes a change in the injection quantity characteristic and, in turn, a change in the engine control characteristic, which may cause problems such as engine stall. There is sex.

  An object of the present invention is to provide a fuel injection valve that improves seat oil tightness and reduces changes in injection quantity characteristics.

In order to achieve the above-described object, the present invention provides a valve seat portion that is provided on the upstream side of the nozzle hole and is configured as a substantially conical valve seat that tapers from the upstream side to the downstream side, and the valve A valve body that opens and closes a fuel passage in cooperation with a seat and is in a valve-closed state by contacting the valve-seat seat part, and is opened by being separated from the valve-seat sheet part In the fuel injection valve provided with a valve body having a surface, the surface roughness interval in the vicinity of the valve seat portion is Sm ₁ , the height (mountain-valley) constituting the surface roughness is H ₁ , and the vicinity of the valve seat portion When the surface roughness interval is Sm ₂ and the peak height constituting the surface roughness is H ₂ ,
Sm ₁ ≈n × Sm ₂ ,
H ₁ ≈n × H ₂ (n is an arbitrary natural number)
It is possible to improve the seat oil tightness in a state where the valve seat portion and the valve seat portion are in contact with each other in a state where an electric signal is not given to the fuel injection valve. Become.

Alternatively, the following relationship may be established.
Sm ₂ ≈n × Sm ₁ ,
H ₂ ≈n × H ₁ (where n is an arbitrary natural number)

Further, the shape of the peaks and valleys constituting the valve body and the seat portion of the valve seat is uniform in the vicinity of the seat portion, and the angle formed by the peaks and valleys in the vicinity of the seat portion of the valve body and the valve seat is θ ₁ , If θ ₂
θ ₁ ≈ θ ₂
It is good to comprise so that.

  According to the present invention, it is possible to easily and inexpensively manufacture the surface shapes of the valve body and the seat portion of the valve seat, and it is possible to improve the seat oil-tight performance. Further, since there is almost no need to consider the deformation that occurs in the vicinity of the seat portion, the amount of change in the valve body stroke is small, and there is almost no deterioration in the injection amount characteristics due to the deformation in the vicinity of the seat portion of the valve body and the valve seat over time. That is, it is possible to provide a fuel injection valve that is extremely unlikely to cause a change in engine control characteristics because the injection amount characteristics hardly change while realizing an improvement in seat oil tightness at a low cost.

1 is a longitudinal sectional view showing the overall configuration of a fuel injection valve according to an embodiment of the present invention. The longitudinal cross-sectional view which shows the sheet | seat part vicinity. The detailed enlarged view of the longitudinal cross-sectional view of FIG. Sectional drawing which shows the valve closing state of the seat part vicinity of FIG. The figure which shows the relationship between the contact width b shown in FIG. 4, and the biting amount h. The figure which defined the parameter which forms a sheet surface. Is an example of a sheet _{surface, Sm 1 ≒ Sm 2, H} 1 ≒ H 2, shows a θ ₁ ≒ θ _2. The figure which shows the case where the contact position has shifted | deviated in FIG. The figure which shows the case where the magnitude | sizes of the peak side R shape and the valley side R shape which are examples of a sheet surface differ. FIG. 4 is a diagram illustrating an example of a sheet surface where Sm ₁ ≈n × Sm ₂ and H ₁ ≈n × H ₂ (where n = 2).

  Embodiments according to the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing the overall configuration of a fuel injection valve according to an embodiment of the present invention. The fuel injection valve of the present embodiment is a fuel injection valve that directly injects fuel such as gasoline into an engine cylinder (combustion chamber).

  The fuel injection valve body 1 includes a hollow fixed core 2, a yoke 3 that also serves as a housing, a mover 4, and a nozzle body 5. The mover 4 includes a movable core 40 and a movable valve body 41. Here, the fixed core 2, the yoke 3 and the movable core 40 are components of the magnetic circuit.

  The yoke 3, the nozzle body 5, and the fixed core 2 are joined by welding. There are various coupling modes. In this embodiment, the nozzle body 5 and the fixed core 2 are welded and joined in a state where a part of the inner periphery of the nozzle body 5 is fitted to a part of the outer periphery of the fixed core 2. Has been. Further, the nozzle body 5 and the yoke 3 are joined by welding so that the yoke 3 surrounds a part of the outer periphery of the nozzle body 5. An electromagnetic coil 6 is incorporated inside the yoke 3. The electromagnetic coil 6 is covered with a yoke 3, a resin cover 23, and a part of the nozzle body 5 while maintaining a sealing property.

  The mover 4 is incorporated in the nozzle body 5 so as to be movable in the axial direction 24. An orifice cup 7 which is a part of the nozzle body is fixed to the tip of the nozzle body 5 by welding.

  Inside the fixed core 2, a spring 8 that presses the movable element 4 against the seat portion 7B, an adjuster 9 that adjusts the spring force of the spring 8, and a filter 10 are incorporated.

  A guide member 12 that guides the movement of the movable element 4 in the axial direction 24 is provided inside the nozzle body 5 and the orifice cup 7. The guide member 12 is fixed to the orifice cup 7. A guide member 11 that guides the movement of the mover 4 in the axial direction 24 near the movable core 40 is provided. The mover 4 is moved in the axial direction 24 by the guide members 11 and 12 arranged vertically. Guided.

  The valve body (valve rod) 41 of the present embodiment is a needle type with a tapered tip, but may be of a type in which a sphere is provided at the tip.

  The fuel passage in the fuel injection valve includes an inside of the fixed core 2, a plurality of holes 13 provided in the movable core 40, a plurality of holes 14 provided in the guide member 11, the inside of the nozzle body 5, and the guide member 12. And a conical surface 7A including the sheet portion 7B.

  The resin cover 23 is provided with a connector portion 23A for supplying an exciting current (pulse current) to the electromagnetic coil 6, and a part of the lead terminal 18 insulated by the resin cover 23 is located in the connector portion 23A.

  When the electromagnetic coil 6 accommodated in the yoke 3 is excited by the external drive circuit (not shown) via the lead terminal 18, the fixed core 2, the yoke 3 and the movable core 40 form a magnetic circuit, and the movable element 4 Is magnetically attracted to the fixed core 2 side against the force of the spring 8. At this time, the valve body 41 is separated from the seat portion 7B and is in an open state, and the fuel in the fuel injection valve body 1 that has been pressurized (1 MPa or more) in advance by an external high-pressure pump (not shown) 72 (see FIG. 2).

  When the excitation of the electromagnetic coil 6 is turned off, the valve element 41 is pressed against the seat portion 7B side by the force of the spring 8, and the valve is closed.

  Next, the detailed configuration of the main part of the fuel injection valve according to the present embodiment will be described with reference to FIGS.

  FIG. 2 is a cross-sectional view of the vicinity of the seat portion of the fuel injection valve. A plurality of nozzle holes 71 and 72 and a conical surface 7A including the sheet portion 7B are formed in the orifice cup 7 on the downstream side of the sheet portion 7B. FIG. 3 is an enlarged view of FIG. FIG. 4 shows a partially enlarged view of the vicinity of the sheet portion 7B in FIG. 3 surrounded by an ellipse. In FIG. 4, the valve body 41 is shown on the upper side, and the orifice cup 7 is shown on the lower side, showing a closed state. In this state, the contact portion between the valve body 41 and the orifice cup 7 is elastically deformed, and therefore is accompanied by an amount of biting h and a contact width b due to the deformation. In the fuel injection valve of the embodiment, the biting amount h is 0.1 to 0.6 um, and the contact width b is about 20 to 80 um. FIG. 5 shows the relationship between the biting amount h and the contact width b.

  In FIG. 3, the seat portion 7B is a valve seat portion configured as a substantially conical valve seat (conical surface 7A) that tapers from the upstream side toward the downstream side, and comes into contact with the seat portion 7B. A valve body sheet portion is formed in the valve body 41. The valve body seat part overlaps with the seat part 7B in FIG.

  Moreover, although the present Example shows the case where there are two nozzle holes, it may be one or three or more.

  FIG. 6 shows an enlarged state so that the surface state of the contact portion between the valve body 41 and the orifice cup 7 shown in FIG. 4 can be seen. Here, the valve body 41 and the orifice cup 7 are separated so that the explanation of the figure can be easily understood.

In the sheet surface shape, peaks and valleys are regularly arranged, the interval between the peaks and the peaks is Sm, the height of the peaks and valleys is H, and the angle between the peaks or valleys is θ. Assume that the valve body 41 side is Sm ₁ , H ₁ , θ ₁ , and the orifice cup side is Sm ₂ , H ₂ , θ ₂ .

  Next, the mechanism for improving the oil tightness of the seat according to this embodiment will be described with reference to FIGS.

FIG. 7 shows a case where Sm ₁ ≈Sm ₂ , H ₁ ≈H ₂ , θ ₁ ≈θ ₂ ≈90 degrees. In this case, since the surface state on the valve body 41 and the orifice cup 7 side is substantially the same, a plurality of ridges and valleys on the other side are engaged in a closed state. Therefore, since a plurality of minute gaps composed of peaks and valleys overlap, a pressure drop can be expected due to the labyrinth effect, and an improvement in seat oil tightness can be expected.

  However, as shown in FIG. 8, there may be a case where peaks and valleys are not accurately bitten. In this case, the slopes of the valve body 41 and the orifice cup 7 on the crests and troughs form a contact portion, and the surface oil tightness can be improved by increasing the surface pressure.

  Further, as shown in FIG. 9, it is also assumed that the tip shapes of the crests and troughs of the valve body 41 or the orifice cup 7 are different. When the surface state formed by processing is taken into consideration, the peak side R tends to be larger than the size of the valley side R as shown in FIG. At this time, as shown in the detailed view of part A of FIG. 9, the height H ′ of the top 7d formed on the peak side R is a peak and valley that are the reference in which the size of the valley side R and the size of the peak side R are equal. It is desirable to be higher than half of the height H of the top 7d 'to be formed. Thereby, since the contact part of the slope concerning the peak and trough of the valve body 41 and the orifice cup 7 is obtained stably, an effect is seen in seat oil-tight performance improvement. The relationship between the peaks and valleys on the valve body 41 side can be considered in the same manner as the relationship between the peaks and valleys on the orifice cup 7 side.

  Moreover, the state where the peak side R shown in FIG. 9 is larger than the valley side R can take into account the wear caused by the so-called valve body 41 and orifice cup 7 repeating the operation over time. If the peak height H ′ formed on the peak side R is higher than half of the reference height H as described above, the slopes of the valve body 41 and the orifice cup 7 on the peaks and valleys regardless of the wear on the peak. The contact portion sheet position between them hardly changes.

  Therefore, the seat oil-tight performance does not deteriorate over time, and the stroke performance of the valve body 41 is not changed, so that it can be said that the engine control performance hardly changes.

As another form of the present embodiment, the states of Sm ₁ ≈2 × Sm ₂ and H ₁ ≈2 × H ₂ are shown (that is, the case where n≈2 in the above formula). In this case, the contact portion formed by the slopes over the peaks and valleys of the valve body 41 and the orifice 7 is reduced to ½ compared to the case of n = 1, but the surface formed by the contact between the slopes. Since the effect of increasing the pressure can be expected, an improvement in seat oil tightness can be expected.

DESCRIPTION OF SYMBOLS 1 Injection valve main body 2 Fixed core 3 Yoke 4 Movable element 5 Nozzle body 6 Electromagnetic coil 7 Orifice cup 7A Conical surface 7B Sheet | seat part 7C Convex curved surface part 8 Spring 9 Adjuster 10 Filter 11, 12 Guide member 13 Several provided in the movable core Holes 14 provided in the guide member 11 holes 15 provided in the guide member 12 lead terminals 23 resin cover 40 movable core 41 valve bodies 71 to 76 injection holes (orifices)
81-86 recess

Claims (3)

A valve seat provided on the upstream side of the nozzle hole; a valve body that is closed by contact with the valve seat; and a valve that is opened by being separated from the valve seat; and the valve In a fuel injection valve used for an internal combustion engine of an automobile, comprising a substantially conical cone-shaped portion formed with a seat seat portion and tapering from the upstream side toward the downstream side,
Between the surface roughness interval Sm ₁ on the contact surface of the valve seat portion with the valve seat portion and the surface roughness interval Sm ₂ on the contact surface of the valve seat portion with the valve seat portion ,
A fuel injection valve having a relationship of either Sm ₁ = n × Sm ₂ or Sm ₂ = n × Sm ₁ (n is an arbitrary natural number). The fuel injection valve according to claim 1, wherein
The relationship of Sm ₁ ≧ Sm ₂ is established, and the surface roughness H ₁ of the contact surface of the valve seat portion with the valve seat portion and the contact surface of the valve seat portion with the valve seat portion It has a relationship of H ₁ = n × H ₂ (n is an arbitrary natural number) with the surface roughness H ₂ .
Alternatively, a relationship of Sm ₂ ≧ Sm ₁ is established, and H ₂ = n × H ₁ (n is optional) between the valve seat surface roughness H ₁ and the valve seat surface roughness H ₂ (Natural number) relationship, a fuel injection valve. The fuel injection valve according to claim 1 or 2,
Crests and valleys forming a surface roughness H ₁ at the contact surface of the valve seat portion with the valve seat portion and a surface roughness H ₂ at the contact surface of the valve seat portion with the valve seat portion. A fuel injection valve having a relationship of θ ₁ = θ ₂ between the angles θ ₁ and θ ₂ .

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