JP2018123720A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce bound of a valve element occurring at the time of valve close, in a fuel injection device used for an internal combustion engine.SOLUTION: A fuel injection device includes: a valve element coming into contact with a valve seat to seal; a movable iron core for driving the valve element; and a stationary iron core disposed while facing the movable iron core. The valve element has a density that is lower than a density of the valve seat.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a fuel injection device.

  There exists a thing of patent document 1 (Unexamined-Japanese-Patent No. 2010-14124) as a prior art of this invention. As shown in Patent Document 1, a fuel injection device that injects fuel from an injection hole using a magnetic attraction generated by energization of a coil is known. In such a fuel injection device, when a coil is energized, a magnetic attractive force is generated between the fixed iron core and the movable iron core. In addition, the valve body integrated with the movable iron core attracts the movable iron core toward the fixed iron core due to the magnetic attraction generated between the movable iron core and the fixed iron core, and transmits the force to the valve element. Move in the direction of separation. The movement of the integrated movable core and valve body is restricted by colliding with the fixed core, and the stop position is determined.

  In this case, the movable iron core integrated with the valve body collides with the fixed iron core, and the movable iron core rebounds from the fixed iron core due to the impact of the collision. When energization of the coil is stopped, the magnetic attractive force acting between the movable iron core and the fixed iron core disappears, and if the elastic force of the elastic member urged by the valve body becomes smaller, the valve body That is, the valve closing direction movement is started. When the valve body and the movable iron core collide with each other, the movement is restricted, and the stationary position is determined. In this case, since the valve body collides with the valve seat, the valve body moves in a direction away from the valve seat due to the impact of the collision, and if a gap is generated between the valve body and the valve seat, the fuel is injected as uncontrollable fuel. It is ejected from the hole to the outside.

  In order to suppress such uncontrollable fuel injection, a configuration in which the movable iron core and the valve body are separated as disclosed in Patent Document 1 has been proposed.

JP 2010-14124 A

  In a fuel injection device that opens and closes the valve body by switching between energization and de-energization as in the prior art, when the valve body bounces due to elastic deformation due to collision between the valve body and the valve seat when the valve is closed There is.

  Therefore, an object of the present invention is to reduce the bounce caused by elastic deformation at the time of a collision between a valve body and a valve seat.

  In order to solve the above-described problem, a fuel injection device 100 of the present invention is arranged to face a valve body 101 that contacts and seals a valve seat 102, a movable iron core 106 that drives the valve body 101, and the movable iron core. And the density of the valve body 101 is smaller than the density of the valve seat 102.

  Thereby, since the valve body 101 becomes lightweight, when the valve body 101 closes, the kinetic energy at the time of colliding with the valve seat 102 can be reduced. For this reason, the amount of deformation of the valve seat 102 when the valve body 101 closes and collides with the valve seat 102 can be reduced. For this reason, the elastic energy received by the valve body 101 when returning to the original shape by the restoring force from the deformation of the valve seat 102 is reduced, and the bounce amount of the valve body 101 after the valve body 101 is separated from the valve body 102 is reduced. It becomes possible.

It is sectional drawing which shows embodiment of the fuel-injection apparatus which concerns on the 1st Example of this invention. It is the figure which showed the behavior at the time of the bounding of the valve body of the fuel-injection apparatus which concerns on 1st Example of this invention. It is the figure which showed the motion at the time of the bounding of the valve body of the fuel injection apparatus which concerns on 1st Example of this invention. It is the figure which showed the behavior at the time of the bounding of the valve body of the fuel-injection apparatus which concerns on 1st Example of this invention. It is sectional drawing of the valve body which shows embodiment of the fuel-injection apparatus which concerns on the 1st Example of this invention. It is sectional drawing of the valve body which shows embodiment of the fuel-injection apparatus which concerns on the 1st Example of this invention. It is the figure which showed the bounce amount of the valve body with respect to the density ratio of the valve body of the fuel injection apparatus which concerns on 1st Example of this invention, and a valve seat, and the reduction rate of the bounce. It is the figure which showed the behavior at the time of the bounding of the valve body of the fuel-injection apparatus which concerns on 1st Example of this invention.

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

  FIG. 1 is a cross-sectional view showing an example of an electromagnetic fuel injection device as an example of a fuel injection device according to the present invention. In this embodiment, it is called a fuel injection device, but it may be called a fuel injection valve or an injector.

  In FIG. 1, fuel is supplied from a fuel supply port 112 and supplied into the fuel injection device. The electromagnetic fuel injection device 100 has a valve body 101 inside, and a valve seat 102 is provided at a position facing the valve body 101. The valve seat 102 has a fuel injection hole (not shown). Further, the valve body 101 has a flange portion 113 on the upstream side, a spring 110 is provided so as to be in contact with the flange portion 113, and the valve body 101 is connected via a biasing force transmission surface 114 provided on the flange portion 113. Energized in the valve closing direction. Furthermore, the valve body 101 has a seat portion 115 that forms a seal seat in contact with the valve seat 102. When the coil 108 is not energized, the valve body 101 is pressed against the valve seat 102 by the spring 110, and the fuel It has a structure that seals.

  In the description of the present invention, the fuel supply port side will be described as the upstream side and the valve seat side as the downstream side with respect to the axial direction of the fuel injection device 100.

  When the coil 108 shown in FIG. 1 is energized, a magnetic flux is generated in the fixed iron core 107, the yoke 109, and the movable iron core 106 constituting the magnetic circuit of the solenoid valve, and the gap between the fixed iron core 107 and the movable iron core 106 having a gap is generated. Magnetic attraction is generated. When the magnetic attractive force becomes larger than the force of the urging force of the spring 110 and the fuel pressure, the valve body 101 is attracted to the fixed iron core 107 side by the movable iron core 106 and is opened.

  On the other hand, when energization of the coil 108 is stopped, the magnetic flux generated in the fixed iron core 107 disappears, the magnetic attractive force acting on the movable iron core 106 also decreases, and eventually disappears. As a result, when the force of the biasing spring 110 acting on the valve body 101 becomes larger than the magnetic attractive force acting on the movable core 106, the valve body 101 is displaced downstream, and the valve body 101, the seat member 102, Comes into contact with each other and the valve is closed.

  The above explains the basic operation of the electromagnetic fuel injection device. The fuel injection device controls the fuel injection amount by controlling the time during which the valve element 101 is in the open state by controlling the energization time to the coil 108.

  However, in the fuel injection device that opens and closes the valve body 101 by switching between energization and non-energization of the coil 108 in this way, when the valve is closed, due to elastic deformation due to the collision between the valve body 101 and the valve seat 102, the valve body 101 Bound may occur.

  Here, a phenomenon in which the valve body bounces in the fuel injection device will be described with reference to FIGS. 2, D1 indicates the displacement of the flange portion 113 of the valve body 101, and D2 indicates the displacement of the seat portion 115 of the valve body.

  As shown in FIGS. 2 and 3, both the flange portion 113 and the seat portion 115 of the valve body that have collided with the valve seat 102 at time T <b> 1 move in the direction of the valve seat 102. Thereafter, at time T2, the displacement of the flange 113 of the valve body is minimized, and the kinetic energy stored immediately before the collision is converted into the elastic energy of the valve body 101.

  After the displacement of the flange portion 113 of the valve body 101 is minimized, the flange portion 113 starts to move away from the valve seat 102, that is, in the valve opening direction. The collar portion 113 reaches the maximum speed at the time T3, the position of balance by the urging force of the spring 110, the fuel pressure acting in the vicinity of the seat portion 115, and the restoring force accompanying the expansion and contraction of the valve body 101 and the seat portion 115. The seat portion 115 is separated from the valve seat 102 by the force due to inertia, and bouncing occurs at time T4. The bound amount is a distance G1 in the axial direction between the seat portion 115 and the valve seat 102. Although it is possible to reduce the initial energy of the valve body 101 by dividing the movable iron core 113, the bouncing phenomenon generated by the expansion and contraction of the valve body 101 cannot be suppressed. Reduction of bounce accompanying expansion and contraction has been an issue.

  Then, the present inventors have not been able to suppress the restoring force resulting from the elastic deformation of the valve seat 102 caused by the collision of the valve body 101 and the bouncing phenomenon generated by the expansion and contraction of the valve body 101 after intensive studies. It has been found that it is necessary to reduce the restoring force of the valve seat 102 and the bounce accompanying the expansion and contraction of the valve body 101.

  From the above, the problem to be solved by the present invention is to reduce the bounce caused by the elastic deformation at the time of collision between the valve body 101 and the valve seat 102. The fuel injection device of the present embodiment for solving this problem will be described below.

<Content of Claim 1>
The fuel injection device 100 of the present embodiment includes a valve body 101 that contacts and seals the valve seat 102, a movable core 106 that drives the valve body 101, and a fixed core that is disposed to face the movable core. Prepared. In this embodiment, the density of the valve body 101 is configured to be smaller than the density of the valve seat 102.

<Operation and Effect of Claim 1>
The operation and effect of this embodiment will be described with reference to FIG. R1 and R2 in FIG. 4 indicate the displacement after the collision of the seat portion 115 of the valve body 101 obtained when the collision analysis between the valve body 101 and the valve seat 102 is performed. R1 indicates the displacement when the valve body 101 not using this embodiment is used, and R2 indicates the displacement when the density of the valve body 101 is 1/3. In addition, this time, the displacement is shown when an aluminum alloy (density: one third of R1, rigidity: one third of R1) is used as R2.

  L1 and L2 are maximum values that have advanced downstream from the collision position due to elastic deformation of the valve seat 102 when the valve body 101 collides with the valve seat 102. That is, after the valve body 101 collides with the valve seat 102, the valve body 101 is recessed downstream due to the elastic deformation of the valve seat 102. The retraction of the valve body 101 into the valve seat 102 causes a force that the valve seat 102 tries to restore upstream, thereby increasing the amount of bounce of the valve body 101 upstream. Actually, L3 and L4 are the maximum values of the bounce amount that the valve body 101 is separated from the valve seat 102 after the collision and bounces upstream.

  Therefore, in this embodiment, as shown in FIG. 4, the valve body 101 is lightened by reducing the density of the valve body 101. Thereby, the kinetic energy at the time of the collision of the valve body 101 and the valve seat 102 can be reduced. Therefore, it is possible to reduce the amount of displacement of the valve body 101, which corresponds to the amount of deformation of the valve seat 102 after the collision, as shown in FIG. 4 (L2 → L1).

  As a result, the elastic energy received by the valve body 101 when the valve seat 102 returns to the original shape by the restoring force from the deformation of the valve seat 102 becomes small, and after the collision after the valve body 101 leaves the valve body 102 as shown in FIG. The amount of bound to the upstream side of the valve body 101 can be reduced (L4 → L3). Therefore, since variation in valve closing completion timing can be suppressed, the fuel injection amount can be controlled with high accuracy.

<Contents and effects of claims 2 and 3>
FIG. 5 shows a specific configuration of the valve body 101 of this embodiment. The valve body 101a shown in the left diagram of FIG. 5 is configured by a seal portion 202 that contacts and seals the upstream valve body upper portion 201 when the fuel supply port side is the upstream side and the valve seat 102 side is the downstream side. The In addition, as shown to the valve body 101b of the right figure of FIG. 5, you may comprise the valve body upper part 201 and the valve body front-end | tip part 202 integrally.

  The valve body 101a shown in the left figure of FIG. 5 is composed of a valve body upper portion 201 formed integrally with a seal portion 202 that contacts and seals with the valve seat 102, and the density of the valve body upper portion 201 is at least partially. It is configured to be smaller than the density of the valve seat 102.

  Also in the valve body 101 (101a, 101b) of this configuration, the entire valve body 101 (101a, 101b) including the valve body tip portion 202 is lightweight, so that the kinetic energy at the time of collision with the valve seat 102 is small. Thus, the elastic energy accompanying the elastic deformation of the valve seat 102 after the collision is reduced, and the bounce of the valve body 101 (101a, 101b) is reduced.

  Further, when the density of the seal portion 202 and the valve body upper portion 201 of the valve body 101 (101a, 101b) of this configuration is configured to be smaller than the density of the valve seat 102, the density of only the valve body upper portion 201 is reduced. Compared with the case where it does, the bigger bounce reduction effect is acquired.

<Contents and effects of claim 4>
Further, it is desirable that the density of the valve body upper portion 201 of the valve body 101a constituted by the valve body upper portion 201 formed integrally with the seal portion that contacts and seals with the valve seat 102 is smaller than that of the seal portion 202. . This is because the valve body upper portion 201 has a larger volume than the seal portion 202, and thus the entire valve body can be reduced in weight. Therefore, the kinetic energy when the valve body 101 collides with the valve seat 102 can be reduced, and the bounce of the valve body 101 can be suppressed.

<Contents and effects of claim 5>
In addition, as shown in FIG. 6, the portion where the valve body 101a contacts and seals the valve seat 102 is joined to the ball-shaped portion 301 and the portion other than the portion formed integrally is a rod-shaped portion 302. Similar effects and actions can be obtained. Moreover, in the case of this shape, it becomes possible to suppress manufacturing cost.

<Contents and effects of claim 6>
In the present embodiment, it is desirable that the density of the valve body 101 is about 4/5 or less of the density of the valve seat 102. The effect | action and effect by this are demonstrated based on FIG. FIG. 7 shows the density ratio between the valve body 101 and the valve seat 102, the bounce amount of the valve body 101, the density ratio, and the bounce reduction rate. In the analysis, the rigidity of the valve body 101 used for the analysis is the same value as that of the conventional member. As shown in FIG. 7, the density ratio is 0.8 or less, that is, the density of the valve seat 101 is the density of the valve seat 102. By setting it to 4/5 or less, the bound amount of the valve element can be reduced by 20% or more. As a result, variation in valve closing completion timing can be suppressed, so that the fuel injection amount can be accurately controlled.

<Contents and effects of claim 7>
In the above description, the density is focused on the bounce reduction of the valve body 101, but hereinafter, the description will be focused on the rigidity.

  The rigidity of the valve body 101 is configured to be greater than the rigidity of the valve seat 102 of the fuel injection device 100. By making the rigidity of the valve body 101 greater than that of the valve body 102, when the valve body 101 collides when the valve seat 102 is closed, the valve body undergoes elastic deformation, but the rigidity of the valve body 101 is greater than that of the valve seat 102. Also, the elastic deformation of the valve body 101 at the time of a collision can be suppressed. Thereby, the expansion and contraction of the valve body 101 itself is suppressed, and the valve body bounding caused by the expansion and contraction after the collision of the valve body 101 can be reduced.

<Contents and effects of claim 8>
Further, in the valve body 101a constituted by the valve body upper portion 201 formed integrally with the seal portion that contacts and seals with the valve seat 102 as shown in FIG. The rigidity of the valve seat 102 is desirably smaller than that of the valve seat 102. This is because, when the valve body 101 collides with the valve seat 102, the valve body 101 undergoes elastic deformation, but the elastic energy generated by the elastic deformation is transferred to the valve body upper part 201, and the expansion and contraction of the valve body upper part 201 occurs. Become. Thereby, when the valve body 101 bounces after the collision with the valve seat 102, the expansion and contraction of the seal portion 202 after the collision with the valve seat 102 of the seal portion 202 is suppressed, and the bounce of the valve body 101 can be reduced.

<Contents and effects of claim 9>
Further, the rigidity of the valve body upper portion 201 of the valve body 101a formed of the valve body upper portion 201 formed integrally with the seal portion that contacts and seals with the valve seat 102 as shown in FIG. It is desirable to be smaller. Even in this case, the elastic energy generated by the elastic deformation of the valve body 101 when the valve body 101 collides with the valve seat 102 can be transferred to the valve body upper portion 201. Thereby, expansion / contraction of the seal part 202 after the collision with the valve seat 102 of the seal part 202 is suppressed, and the bounce of the valve body 101 can be reduced.

  In addition, as shown in FIG. 6, the portion where the valve body 101a contacts and seals the valve seat 102 is joined to the ball-shaped portion 301 and the portion other than the portion formed integrally is a rod-shaped portion 302. Similar effects and actions can be obtained. Moreover, in the case of this shape, it becomes possible to suppress manufacturing cost.

<Contents and effects of claim 10>
Further, the density and rigidity of the valve body 101 described above are configured so that the density is lower and the rigidity is higher than the density and rigidity of the valve seat 102.

  8 shows that the density and rigidity of the valve body 101 are smaller than the density and rigidity of the valve seat 102 in the bounding displacements R1 and R2 of the valve body 101 after the collision in FIG. 1) The bounce displacement R3 after the collision when the rigidity is increased (about 1.5 times that of the valve body 101) is added. L1, L2, and L5 are the maximum values that have advanced downstream due to the elastic deformation of the valve seat 102 when the valve body 101 collides, and L3, L4, and L6 are separated from the valve seat 102 after the collision of the valve body 101 and upstream. This is the maximum bounce amount bound to the side.

  By making the density of the valve body 101 smaller than the density of the valve seat 102, the valve body 101 becomes light and the kinetic energy at the time of the collision with the valve seat 102 can be reduced. Further, by making the rigidity of the valve body 101 larger than the rigidity of the valve seat 102, the expansion and contraction of the valve body 101 due to the elastic deformation of the valve body 101 when the valve body 101 collides with the valve seat 102 can be reduced.

  As shown in the enlarged view on the right side of FIG. 8, due to these two actions and effects, the amount of displacement advanced in the downstream direction of the valve body 101 after the collision between the valve body 101 and the valve seat 102 is as shown in FIG. It is possible to reduce the size (L2 → L1 → L5). As a result, the elastic energy received by the valve body 101 when the valve seat 102 returns to its original shape by the restoring force from the deformation of the valve seat 102 is reduced, and the bounce amount due to the expansion and contraction of the valve body 101 can also be reduced. Therefore, as shown in the left diagram of FIG. 8, compared to the case where the density of the valve body 101 is made smaller than the density of the valve seat 102 or the case where the rigidity of the valve body 101 is made larger than the rigidity of the valve seat 102. The bound amount of the valve body 101 after the collision after the valve body 101 is separated from the valve body 102 can be further reduced (L4 → L3 → L6). As a result, variation in valve closing completion timing can be suppressed, so that the fuel injection amount can be controlled with higher accuracy.

Valve body ... 101, 101a, 101b, 101c
Valve seat ... 102,
Movable iron core 106,
Fixed iron core 107,
Coil ... 108,
York ... 109,
Spring ... 110,
Fuel supply port 112,
Brim part 113,
Transmission surface of urging force ... 114
Sheet part ... 115
Upper part of valve body ... 201
Seal part ... 202
Ball-shaped part ... 301
Rod-shaped part ... 302

Claims (10)

A valve body that seals in contact with the valve seat;
The movable iron core for driving the valve body;
In a fuel injection device comprising a fixed iron core disposed opposite to the movable iron core,
A fuel injection device, wherein the density of the valve body is smaller than the density of the valve seat. The fuel injection device according to claim 1,
The valve body is configured by a seal portion that contacts and seals with the valve seat, and a portion that is integrally formed by joining with the seal portion, and the density of the portion is smaller than the density of the valve seat. The fuel-injection apparatus characterized by the above-mentioned. The fuel injection device according to claim 1,
The valve body includes a seal portion that contacts and seals with the valve seat, and a portion that is integrally formed by joining with the seal portion, and the density of the seal portion and the portion is the density of the valve seat. A fuel injection device characterized by being smaller than density. The fuel injection device according to claim 1,
The valve body is configured by a seal portion that contacts and seals with the valve seat, and a portion that is integrally formed with the seal portion, and the density of the portion is smaller than the density of the seal portion. The fuel-injection apparatus characterized by the above-mentioned. The fuel injection device according to any one of claims 2 to 4,
The fuel injection device according to claim 1, wherein the seal portion is configured in a ball shape, and the portion joined to the seal portion is configured in a rod shape. The fuel injection device according to claim 1,
The fuel injection device according to claim 1, wherein the density of the valve body is about 4/5 or less of the density of the valve seat. A valve body that seals in contact with the valve seat;
The movable iron core for driving the valve body;
In a fuel injection device comprising a fixed iron core disposed opposite to the movable iron core,
A fuel injection device characterized in that the rigidity of the valve body is greater than the rigidity of the valve seat. The fuel injection device according to claim 7, wherein
The valve body is composed of a seal part that contacts and seals with the valve seat, and a part that is integrally formed with the seal part.
The fuel injection device according to claim 1, wherein a rigidity of the portion joined to the seal portion is smaller than a rigidity of the valve seat. The fuel injection device according to claim 7, wherein
The valve body is composed of a seal part that contacts and seals with the valve seat, and a part that is integrally formed with the seal part.
A fuel injection device, wherein the seal portion is configured to have a rigidity greater than that of the portion. The fuel injection device according to claim 7, wherein
A fuel injection device, wherein the density of the valve body is smaller than the density of the valve seat.

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