JP2018013051A - Fuel injection valve - Google Patents

Abstract

Provided is a fuel injection valve in which the effect of suppressing the remaining of fuel is less likely to deteriorate even when time has elapsed. A fuel injection valve moves or approaches in a direction away from a valve body, a nozzle cap connected to the valve body, and a valve seat provided in the valve body. And a needle valve 19 that moves in the direction. A plurality of nozzle holes 14 are formed through the bottom wall 131 of the nozzle hole cap 13. When the opening of the nozzle hole 14 in the rear end surface 13A is used as the inlet and the opening of the nozzle hole 14 in the front end surface 13B is used as the outlet, each nozzle hole 14 is positioned so that the outlet is located radially inward of the inlet, or the outlet. Are inclined with respect to the central axis S of the valve body 12 so that their radial positions coincide with the radial position of the inlet. [Selection] Figure 1

Description

  The present invention relates to a fuel injection valve mounted on an internal combustion engine.

  As described in Patent Document 1, an injection hole plate in which a plurality of injection holes are formed is disposed at the tip of the combustion injection valve. And in the fuel injection valve of patent document 1, the coating is given to the wall surface of each nozzle hole, and the front end surface of a nozzle hole plate. By adopting such a configuration, it is difficult for fuel to remain in the nozzle hole or the tip surface of the nozzle hole plate after the fuel injection of the fuel injection valve is completed, and deposits resulting from such residual fuel are less likely to accumulate.

JP 2008-196362 A

  However, the properties of the coating applied to the wall surface of each nozzle hole and the tip surface of the nozzle hole plate may change over time. If the coating characteristics change in this manner, the effect of suppressing the fuel from remaining in the nozzle hole or the tip surface of the nozzle hole plate after the fuel injection of the fuel injection valve ends is reduced. It is easy for deposits to accumulate on the front end surface.

  An object of the present invention is to provide a fuel injection valve in which the effect of suppressing the remaining fuel is less likely to decrease even when time has elapsed.

  A fuel injection valve for solving the above-mentioned problems is a valve body, a nozzle plate facing the tip of the valve body, and a direction moving away from or approaching a valve seat provided in the valve body. And a fuel injection valve that injects fuel from a plurality of injection holes provided in the injection hole plate when the valve element is separated from the valve seat. In this fuel injection valve, the valve seat is inclined so as to be closer to the injection hole plate at a radially inner portion. Further, of both surfaces of the injection hole plate, the surface located on the valve body side is the rear end surface, the surface opposite to the rear end surface is the front end surface, the opening of the injection hole on the rear end surface is the inlet, and the injection surface on the front end surface is When the opening of the hole is used as an outlet, each nozzle hole has a center of the valve body such that the outlet is located radially inward of the inlet or the outlet radial position coincides with the inlet radial position. Each is inclined with respect to the axis.

  According to the above configuration, when the valve body is separated from the valve seat, the fuel flows along the valve seat inclined between the valve body and the valve seat as described above, and each of the nozzle holes provided in the nozzle hole plate is provided. It reaches near the entrance of the nozzle hole.

  When the fuel injection valve injects fuel, the fuel passes through the injection hole. In the nozzle hole, surface tension acts between the wall surface and the fuel. At this time, if the flow velocity of the fuel in the nozzle hole is small, the fuel tends to be left behind in the portion around the outlet of the nozzle hole and the nozzle hole on the rear end surface of the valve body due to the surface tension. That is, the smaller the fuel flow velocity in the nozzle hole, the larger the amount of residual fuel in the nozzle hole and the portion around the outlet of the nozzle hole on the rear end surface of the valve body.

  Here, a fuel injection valve having an injection hole configured such that the outlet is located radially outside the inlet is referred to as a fuel injection valve of the comparative example. In such a fuel injection valve of the comparative example, when the fuel flows into the injection hole at the time of fuel injection, the flow direction of the fuel changes greatly. That is, a large pressure loss occurs when the fuel flows into the nozzle hole. Therefore, the fuel flow velocity in the nozzle hole is significantly reduced as compared with that before flowing into the nozzle hole.

  On the other hand, in the above configuration, each nozzle hole has a central axis of the valve body such that the outlet is located radially inward of the inlet, or the radial position of the outlet coincides with the radial position of the inlet. Respectively. For this reason, the flow direction of the fuel is less likely to change between before the fuel flows into the nozzle hole and after the fuel flows into the nozzle hole, and the flow velocity of the fuel in the nozzle hole compared to before the fuel flows into the nozzle hole. Is suppressed. As a result, the flow rate of the fuel in the nozzle hole is increased as compared with the fuel injection valve of the comparative example. Therefore, it becomes difficult for the fuel to remain in the nozzle hole due to the surface tension. That is, the amount of fuel remaining in the injection hole after the fuel injection of the fuel injection valve is completed can be reduced.

  In the above configuration, the amount of fuel remaining in the nozzle hole is reduced by devising the inclination direction of each nozzle hole as described above. In contrast, even if the fuel injection valve is continuously used, the effect of reducing the amount of fuel remaining in the nozzle hole can be maintained. That is, according to the fuel injection valve, even if time elapses, the effect of suppressing the remaining of the fuel is unlikely to decrease.

Sectional drawing which shows one Embodiment of a fuel injection valve. The top view which shows the front end surface of the bottom wall of the nozzle hole cap in the fuel injection valve. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2. The schematic diagram which shows the positional relationship of the inlet_port | entrance of an injection hole and an exit in the fuel injection valve. The action figure which shows a mode that the fuel injection valve injects a fuel. The top view which shows the front end surface of the bottom wall of the nozzle hole cap in the fuel injection valve of another embodiment.

Hereinafter, an embodiment of a fuel injection valve mounted on an internal combustion engine will be described with reference to FIGS.
As shown in FIG. 1, the housing 11 of the fuel injection valve 10 of the present embodiment has a cylindrical main body 111 extending in the axial direction that is the vertical direction in the drawing. A valve body 12 having a substantially cylindrical shape is attached to the distal end portion (lower end portion in the figure) of the main body 111 so as to protrude downward in the figure. A valve seat 121 is provided at the distal end portion of the valve body 12, and the valve seat 121 is inclined so as to be closer to the distal end at a radially inner portion in the axial direction.

  The valve body 12 is joined with a nozzle cap 13 having a substantially bottomed cylindrical shape. The injection hole cap 13 has a bottom wall 131 as an injection hole plate facing the tip of the valve body 12 and a cylindrical portion 132 facing the outer peripheral surface of the valve body 12. Of the both surfaces of the bottom wall 131 of the nozzle hole cap 13, the surface (upper surface in the figure) facing the tip of the valve body 12 is referred to as “rear end surface 13A”, and the surface opposite to the rear end surface 13A (lower surface in the diagram). In the case of the “front end surface 13B”, the bottom wall 131 is formed with a plurality of injection holes 14 that open to both the rear end surface 13A and the front end surface 13B.

  A fixed iron core 15 made of a magnetic material is provided inside the main body 111 of the housing 11. The fixed iron core 15 is fixed so as not to move with respect to the housing 11, and a movable iron core 16 that slides in the axial direction is interposed between the fixed iron core 15 and the valve body 12 inside the main body 111. Is provided. The movable iron core 16 is urged by a coil spring 17 in a direction away from the fixed iron core 15, that is, in the distal end side.

  In addition, an electromagnetic coil 18 is provided on the outer peripheral side of the fixed core 15 inside the main body 111 of the housing 11. When an electromagnetic force is generated by energizing the electromagnetic coil 18, the movable iron core 16 slides in a direction approaching the fixed iron core 15 against the urging force from the coil spring 17. On the other hand, when no electromagnetic force is generated by the electromagnetic coil 18, the movable iron core 16 slides in a direction away from the fixed iron core 15 by the urging force from the coil spring 17.

  The fuel injection valve 10 also includes a needle valve 19 as a valve body that can move in the axial direction within the valve body 12. The needle valve 19 is connected to the movable iron core 16 and moves together with the movable iron core 16 in the axial direction. When the electromagnetic force is not generated by the electromagnetic coil 18, the needle valve 19 is seated on the valve seat 121, while when the electromagnetic force is generated by the electromagnetic coil 18, the needle valve 19 moves away from the valve seat 121. It is supposed to be.

Next, each nozzle hole 14 will be described with reference to FIGS.
As shown in FIG. 2, a plurality of (six in FIG. 2) nozzle holes 14 are arranged in the bottom wall 131 of the nozzle hole cap 13 along the circumferential direction around the central axis S of the valve body 12. Is provided. The opening of the nozzle hole 14 in the rear end surface 13A of the bottom wall 131 is referred to as an inlet 14A, and the opening of the nozzle hole 14 in the tip surface 13B is referred to as an outlet 14B. In the present embodiment, the positions of the inlets 14 </ b> A of the injection holes 14 are all the same in the radial direction around the central axis S of the valve body 12.

  The cross section shown in FIG. 3 is a cross-sectional view taken along the line 3-3 in FIG. 2, and includes the center of the inlet 14 </ b> A along both the extending direction of the central axis S of the valve body 12 and the direction orthogonal to the central axis S. Part of the cross section. And in this cross section, while passing through the end portion on the radially inner side of the valve seat 121, a point where a straight line LA (broken line in FIG. 3) extending in the inclined direction at the end portion on the inner side in the same radial direction intersects with the rear end face 13A Assume that point X is used. In this case, as shown in FIG. 3, the injection hole 14 is arranged such that the inlet 14 </ b> A is located on the radially inner side from the specified point X. In the radial direction centered on the central axis S, the position of the inlet 14A of the nozzle hole 14 other than the nozzle hole 14 shown in FIG. 3 coincides with the position of the inlet 14A of the nozzle hole 14 shown in FIG. Yes.

  As shown in FIG. 2, in all the nozzle holes 14, the outlets 14 </ b> B are displaced from the inlets 14 </ b> A in both the radial direction and the circumferential direction around the central axis S of the valve body 12. That is, the outlet 14B is located in the clockwise direction in the drawing with respect to the inlet 14A in the circumferential direction, and is located inward of the inlet 14A in the radial direction.

  Specifically, as shown in FIG. 5, the inclination angle of the valve seat 121 with respect to the central axis S of the valve body 12 is defined as “valve seat inclination angle αs”, and the extending direction of the nozzle hole 14 with respect to the central axis S of the valve body 12 Is assumed to be “injection hole inclination angle αh”, the injection hole inclination angle αh satisfies the following relational expression (formula 1).

10 ° ≦ αh ≦ αs + 15 ° (Formula 1)
When the injection hole inclination angle αh is less than 10 ° and when the injection hole inclination angle αh is larger than the sum of the valve seat inclination angle αs and 15 °, the injection hole inclination angle αh and the valve seat inclination angle αs The angle difference becomes too large. In this case, when fuel is injected from the fuel injection valve 10, there is a large difference between the flow direction of the fuel flowing along the valve seat 121 and the flow direction of the fuel in the injection hole 14. The pressure loss increases in the process of flowing into the nozzle hole 14, and the fuel flow rate in the nozzle hole 14 may be reduced. Therefore, each nozzle hole 14 is configured to satisfy the relational expression (Formula 1).

  Further, as shown in FIG. 4, when a straight line passing through the central axis S of the valve body 12 and the inlet 14A of the injection hole 14 is defined as a “reference straight line L1,” a reference straight line on a plane orthogonal to the central axis S is obtained. The inclination angle β in the extending direction of the nozzle hole 14 with respect to L1 is greater than 90 ° and less than 270 °. In this embodiment, the amount of deviation between the radial position of the inlet 14A and the radial position of the outlet 14B in each nozzle hole 14, that is, the inclination angle β is all the same.

Next, the operation of the fuel injection valve 10 according to the present embodiment will be described with reference to FIG.
When electromagnetic force is generated by energizing the electromagnetic coil 18, the needle valve 19 is separated from the valve seat 121. Then, as shown by an arrow in FIG. 5, the fuel flows between the needle valve 19 and the valve seat 121 along the inclined valve seat 121 and is provided on the bottom wall 131 of the injection hole cap 13. The fuel reaches the vicinity of the inlet 14A of each nozzle hole 14. In addition, since the valve seat 121 is inclined as described above, the flow direction of the fuel that has thus reached the vicinity of the inlet 14A includes a component that is directed radially inward.

  When the fuel injection valve 10 injects fuel, the fuel passes through the injection hole 14. In the nozzle hole 14, the surface tension generated between the wall surface and the fuel acts as a force for allowing the fuel to remain in the nozzle hole 14. At this time, the smaller the flow rate of the fuel in the nozzle hole 14, the greater the amount of residual fuel in the nozzle hole 14 after the end of fuel injection.

  Here, a fuel injection valve having an injection hole configured such that the outlet is located radially outside the inlet is referred to as a fuel injection valve of the comparative example. In such a fuel injection valve of the comparative example, when the fuel flows into the injection hole at the time of fuel injection, the flow direction of the fuel changes greatly. That is, a large pressure loss occurs when the fuel flows into the nozzle hole. Therefore, the fuel flow velocity in the nozzle hole is significantly reduced as compared with that before flowing into the nozzle hole.

  On the other hand, in the present embodiment, each nozzle hole 14 is inclined such that the outlet 14B is located radially inward of the inlet 14A. Therefore, the fuel can be caused to flow into the injection hole 14 without changing the flow direction of the fuel flowing along the valve seat 121 so much. Further, the flow direction of the fuel does not change much before the fuel flows into the nozzle hole 14 and after the fuel flows into the nozzle hole 14. As a result, a decrease in the flow rate of the fuel in the nozzle hole 14 is suppressed as compared to before flowing into the nozzle hole 14. As a result, the flow rate of the fuel in the nozzle hole 14 is increased as compared with the fuel injection valve of the comparative example. Therefore, it is difficult for the fuel to be left in the nozzle hole 14 due to the surface tension. That is, the amount of fuel remaining in the nozzle hole 14 after the fuel injection of the fuel injection valve 10 is completed can be reduced.

  In the present embodiment, since the amount of fuel remaining in the nozzle hole 14 is reduced by devising the inclination direction of each nozzle hole 14 as described above, the wall surface of the nozzle hole 14 is coated. Unlike the case where the fuel injection valve 10 is used, the effect of reducing the amount of fuel remaining in the nozzle hole 14 can be maintained even if the fuel injection valve 10 is continuously used. That is, even if time elapses, the effect of suppressing the remaining fuel is unlikely to decrease.

  Incidentally, when all the nozzle holes 14 are configured so that the circumferential position of the outlet 14B coincides with the circumferential position of the inlet 14A, that is, the inclination angle β is “180 °”, each nozzle hole It is difficult to diffuse the fuel injected from 14. In this regard, in this embodiment, all the nozzle holes 14 are configured such that the circumferential position of the outlet 14B is shifted from the circumferential position of the inlet 14A. Therefore, compared with the case where all the nozzle holes 14 are configured so that the circumferential position of the outlet 14B coincides with the circumferential position of the inlet 14A, the amount of residual fuel in each nozzle hole 14 is reduced and the fuel is reduced. The fuel injected from the injection valve 10 can be diffused.

The above embodiment may be changed to another embodiment as described below.
If both the above relational expression (Formula 1) is satisfied and the inclination angle β is greater than 90 ° and less than 270 ° are satisfied, the nozzle hole 14 is The configuration may be such that the radial position of 14B is inclined with respect to the central axis S of the valve body 12 so as to coincide with the radial position of the inlet 14A. Even in this case, the flow rate of the fuel in the injection hole 14 can be made larger than the flow rate of the fuel in the injection hole in the fuel injection valve of the comparative example. Therefore, the same operation and effect as the above embodiment can be obtained.

  -In the said embodiment, each nozzle hole 14 is comprised so that all the said inclination angles (beta) may become the same angle. However, if all the nozzle holes 14 are configured such that the outlets 14B are radially inward of the inlets 14A, the inclination angle β of some of the nozzle holes 14 among the nozzle holes 14 is It may be different from the inclination angle β of the other nozzle holes 14. Moreover, the said inclination | tilt angle (beta) may differ for every nozzle hole 14. FIG.

  If each nozzle hole 14 is configured to be inclined with respect to the central axis S of the valve body 12 so that the outlet 14B is positioned radially inward of the inlet 14A, for example, FIG. Like the nozzle hole 14 surrounded by the dotted line, the nozzle hole 14 in which the circumferential position of the outlet 14B coincides with the circumferential position of the inlet 14A, that is, the inclination angle β is “180 °”. It may be provided on the bottom wall 131 of the nozzle hole cap 13.

  If the radial position of the inlet 14 </ b> A of the injection hole 14 is located radially inward of the specified point X, the radial position of the inlet 14 </ b> A of some of the injection holes 14 is the inlet of another injection hole 14. It may be different from the radial position of 14A. Further, the radial position of the inlet 14 </ b> A may be different for each nozzle hole 14.

  In the above embodiment, the nozzle hole 14 is arranged so that the inlet 14A is positioned radially inward from the specified point X. However, the present invention is not limited to this, and the nozzle hole 14 is positioned at the radial position of the inlet 14A. You may make it arrange | position so that it may correspond with the radial direction position of the regulation point X. FIG. For example, all the nozzle holes 14 may be arranged so that the radial position of the inlet 14A coincides with the radial position of the specified point X, or only a part of the nozzle holes 14 may be disposed on the inlet 14A. You may make it arrange | position so that a radial direction position may correspond with the radial direction position of the regulation point X. FIG.

  Further, the nozzle hole 14 may be arranged such that the inlet 14A is located on the radially outer side from the specified point X. For example, all of the injection holes 14 may be arranged so that the inlets 14A are located radially outside the specified point X, or only some of the injection holes 14 may have the specified points X of the inlet 14A. You may make it arrange | position so that it may be located in the radial direction outer side.

  DESCRIPTION OF SYMBOLS 10 ... Fuel injection valve, 12 ... Valve body, 121 ... Valve seat, 131 ... Bottom wall, 13A ... Rear end surface, 13B ... Front end surface, 14 ... Injection hole, 14A ... Inlet, 14B ... Outlet, 19 ... Needle valve.

Claims (1)

A valve body, an injection hole plate facing the tip of the valve body, and a valve body that moves in a direction away from or in a direction toward the valve seat provided in the valve body,
In the fuel injection valve that injects fuel from a plurality of injection holes provided in the injection hole plate when the valve body is separated from the valve seat,
The valve seat is inclined so as to be closer to the nozzle hole plate toward a radially inner portion,
Of both surfaces of the nozzle hole plate, a surface located on the valve body side is a rear end surface, a surface opposite to the rear end surface is a front end surface, an opening of the nozzle hole in the rear end surface is an inlet, When the opening of the nozzle hole on the tip surface is the outlet,
Each nozzle hole has a central axis of the valve body such that the outlet is located radially inward of the inlet or the radial position of the outlet coincides with the radial position of the inlet. The fuel injection valve is characterized in that each is inclined.

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