JP2015121188A - Fuel injection valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a fact that because the impact force between a valve body and a valve seat is increased by increase of fuel pressure for improving injection quantity accuracy and an atomization characteristic of a fuel injection valve, a valve body is re-opened after closing the valve body, causing unintentional injection of an extremely small amount of fuel.SOLUTION: A fuel injection valve includes a mass damper which comes into contact with a valve body of an electromagnetic fuel injection valve, and a third elastic member which pushes mass damper in a close direction.

Description

  The present invention relates to a fuel injection valve used in an internal combustion engine, and more particularly, to a fuel injector that opens and closes a fuel passage by an electromagnetically driven mover.

  The internal combustion engine is provided with a fuel injection control device that performs an operation of converting an appropriate fuel amount corresponding to an operating state into an injection time of the fuel injection valve, and drives the fuel injection valve that supplies the fuel. The fuel injection valve injects fuel by operating a mover constituting the fuel injection valve by a magnetic force generated by a current flowing through an internal solenoid, and opening and closing the valve body. The amount of fuel to be injected is determined mainly by the pressure difference between the fuel pressure and the atmospheric pressure at the injection port of the fuel injection valve, and the time during which fuel is injected while the valve body is kept open.

  In recent years, since it has been required to further reduce the components contained in the exhaust gas of an internal combustion engine, it has been required to increase the fuel injection pressure as compared with the prior art. Attempts have also been made to reduce the amount of fuel consumed when the vehicle is mounted by reducing the displacement of the internal combustion engine in combination with the supercharger. In this case, since the specific output of the internal combustion engine is improved by supercharging intake air or the like, the fuel injection valve is required to increase the maximum injection amount without increasing the minimum injection amount. Also in this case, increasing the fuel injection pressure as compared with the prior art is an effective means for increasing the maximum injection amount.

  The fuel injection valve includes, for example, a mover having a cylindrical mover and a valve body positioned at the center of the mover, and a stator having a fuel introduction hole that guides fuel to the center. A gap is provided between the end surface of the movable element and the end surface of the mover, and an electromagnetic solenoid that supplies magnetic flux to a magnetic path including the gap is provided. The magnetic attraction force generated between the end face of the mover and the end face of the stator due to the magnetic flux passing through the gap drives the mover by attracting the mover to the stator side, and pulls the valve element away from the valve seat. It is comprised so that the fuel passage provided in may be opened.

  When energization of the electromagnetic solenoid is stopped, the magnetic attractive force acting on the mover disappears, and the pressure drop caused by the force of the elastic member that urges the valve body in the closing direction and the flow rate of the fuel flowing between the valve body and the valve seat As a result, the valve body and the mover move in the closing direction, and the valve body is seated on the valve seat to close the fuel passage.

  In the conventional fuel injection valve configured as described above, as the fuel pressure increases, the pressure drop caused by the flow velocity of the fuel flowing between the valve body and the valve seat increases, and the force for moving the valve body in the closing direction also increases. Therefore, the impact force when the valve body is seated on the valve seat increases, and the reaction causes the valve body to unintentionally leave the valve seat again, and a small amount of fuel is ejected, deteriorating the injection accuracy and particle size characteristics. It has been known.

   As an example of the prior art, in the fuel injection valve disclosed in Patent Document 1, a movable member composed of two parts loaded by a first return spring and a valve closing frictionally connected to the larger movable member. Disclosed is a fuel injection valve having a body, wherein a first mover portion is loaded by a first return spring in a closing direction, and a second mover portion is loaded by a second return spring in a closing direction. ing.

Since the entire two-piece movable element is remarkably small with respect to the entire contact surface formed with the inner pole, the entire movable element is quickly released from the inner pole and the closing operation is performed quickly. Furthermore, if the mass characteristics are well adjusted by using a mover consisting of two parts, the acceleration of the large mover part and the acceleration of the small mover part can be reduced when the excitation current is interrupted. The difference in the time between the two moves the mover parts in the opposite direction, so that the impact of the mover part that bounces back slightly can be eliminated, and unnecessarily opens again for a short time. This is avoided.
As another example of the prior art, in the fuel injection valves disclosed in Patent Documents 2 and 3, since the movable core is separate from the plunger, the plunger moves away from the movable core in the direction opposite to the movement of the movable core. Try this. At this time, fluid friction occurs between the outer periphery of the plunger and the inner periphery of the movable core, and the energy of the rebounding plunger is still moving in the opposite direction (valve closing direction) by the inertial force. Absorbed by mass.

  Since the movable core having a large inertial mass is separated from the plunger at the time of rebounding, the rebounding energy itself is also reduced.

  Moreover, since the inertial force of the movable core that has absorbed the rebound energy of the plunger is reduced by that amount, the energy for compressing the spring is reduced, and the repulsive force of the spring is reduced, and the plunger rebounds due to the rebound phenomenon of the movable core itself. The phenomenon of moving in the valve opening direction does not occur.

  Thus, the rebound of the plunger is minimized, and the so-called secondary injection phenomenon in which the valve is opened after the energization of the electromagnetic solenoid device is cut off and the fuel is randomly injected is suppressed.

Special table 2003-511604 gazette JP 2007-218205 A JP 2011-137442 A

  In the fuel injection valve of the first embodiment described in Patent Document 1, the sum of the mass of a part of the mover and the valve element itself becomes an impact force to the valve seat, although it is divided, against the increasing fuel pressure. This is not enough to prevent the valve body from opening again.

  In the fuel injection valve according to the second embodiment described in Patent Document 1 and the fuel injection valves described in Patent Documents 2 and 3, the mass of the mover is completely separated from the valve body at the time of collision with the valve seat. Therefore, the collision mass with the valve seat is only the valve body, which is more advantageous in preventing the phenomenon that the valve body is opened again than the fuel injection valve described in the first embodiment of Patent Document 1. However, from the viewpoint of increasing fuel pressure and reducing the amount of components contained in the exhaust gas, the valve body is opened again even by the impact force generated when only the valve body collides with the valve seat. It is difficult to prevent the fuel from being ejected.

  In order to solve the above-described problems, the fuel injection valve of the present invention has a mass damper disposed together with the valve body of the electromagnetic fuel injection valve, and an elastic member is provided upstream of the mass damper, thereby bringing the mass damper into contact with the valve body. . The load of the elastic member provided in the upstream part of the mass damper is sufficiently smaller than the load of the elastic member provided in the upstream part of the valve body.

  When the valve body collides with the valve seat, the valve body is pressed against the valve seat by an elastic member having a large load, and the mass damper is in contact with the valve body by an elastic member having a small load. The impact force transmitted to the valve body as a reaction from the valve seat propagates inside the valve body and is transmitted to the mass damper. At this time, due to the load of the elastic member acting on the valve body and the mass damper, the valve body abuts on the valve seat and maintains a stationary state. Instead, the mass damper receives an impact force and moves upstream of the fuel injection valve. By moving, the valve body is opened again after the valve body is closed, and an extremely small amount of fuel can be prevented from being unintentionally injected.

1 is an overall cross-sectional view of a fuel injection valve according to an embodiment of the present invention. It is a partial expanded sectional view at the time of valve opening of the fuel injection valve by embodiment of this invention. It is a partial expanded sectional view at the time of valve closing of the fuel injection valve by the embodiment of the present invention. It is a partial expanded sectional view immediately after valve closing of the fuel injection valve by embodiment of this invention.

  Hereinafter, the configuration of an embodiment of a fuel injection valve according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view of a fuel injection valve in the present embodiment. FIGS. 2 to 4 are partial enlarged views of FIG. 1, which are limited to components that are characteristic of the fuel injection valve in the present embodiment and simplified in shape. In FIGS. 2 to 4, the size of parts and the size of the gap are exaggerated from the actual ratio for easy understanding of the operation and functions, and unnecessary parts are omitted to explain the functions. In each embodiment, the same constituent elements are given the same reference numerals, and redundant descriptions are omitted.

  FIG. 1 is a longitudinal sectional view of a fuel injection valve in the present embodiment. The nozzle holder 101 includes a small diameter cylindrical portion 22 having a small diameter and a large diameter cylindrical portion 23 having a large diameter. An orifice cup 116 having a guide portion 115 and a fuel injection port 117 is inserted into the distal end portion of the small-diameter cylindrical portion 22, and the periphery is welded and fixed in a cylindrical shape. The guide part 115 guides the outer periphery of the tip part 114B of the valve body 114A. A conical valve seat 39 is formed on the orifice cup 116 on the side facing the guide portion 115. The valve seat 39 is in contact with the tip 114B of the valve body 114A to guide or block the flow of fuel to the fuel injection port. A groove is formed on the outer periphery of the nozzle holder 101, and a seal member typified by a resin chip seal 131 is fitted in the groove.

  A stepped portion 129 having a large outer diameter is provided at the end opposite to the tip 114B of the valve body 114A. A seating surface of the spring 110 is provided on the upper end surface of the stepped portion 129, and a spring guide projection 114C is formed at the center.

  The valve body 114 </ b> A passes through a through hole 128 at the center of the movable element 102, and a zero spring 112 is held between the movable element 102 and the rod guide 113.

  Since the diameter of the through hole 128 of the movable element 102 is smaller than the diameter of the stepped portion 129 of the valve body 114A, the biasing force of the spring 110 or the action of gravity that presses the valve body 114A toward the valve seat of the orifice cup 116. Below, the upper surface of the needle | mover 102 hold | maintained by the zero spring 112 and the lower end surface of the step part 129 of the valve body 114A contact | abut, and both are engaging. As a result, the two cooperate in response to the upward movement of the movable element 102 against the urging force or gravity of the zero spring 112 or the downward movement of the valve body 114A along the urging force of the zero spring 112 or gravity. It will move. However, when the force for moving the valve body 114A upward or the force for moving the mover 102 downward acts independently of each other regardless of the urging force or gravity of the zero spring 112, they may move in different directions. it can.

  A stator 107 is press-fitted into the inner peripheral portion of the large-diameter cylindrical portion 23 of the nozzle holder 101, and is welded and joined at the press-fit contact position. A gap formed between the inside of the large-diameter cylindrical portion 23 of the nozzle holder 101 and the outside air is sealed by this welding joint. In the center of the stator 107, a through hole 107D larger than the diameter of the stepped portion 129 of the valve body 114A is provided as a fuel introduction passage.

  The lower end surface of the stator 107 and the upper end surface of the mover 102 may be plated to improve durability. Even when relatively soft soft magnetic stainless steel is used for the stator 107 and the mover 102, durability reliability can be ensured by using hard chrome plating or electroless nickel plating.

  A gap is provided between the through hole 107D of the stator 107 and the outer periphery of the stepped portion 129 of the valve body 114A. This is to prevent magnetic flux leakage from the stator 107 to the valve body 114A and to smoothly pass the fuel that has passed through the through hole 107D.

  The lower end of the initial load setting spring 110 is in contact with the spring receiving surface formed on the upper end surface of the stepped portion 129 of the valve body 114A, and the other end of the spring 110 is inside the through hole 107D of the stator 107. By being received by the adjuster 54 that is press-fitted and fixed to the valve body 114, it is fixed between the stepped portion 129 of the valve body 114 </ b> A and the adjuster 54. By adjusting the fixing position of the adjuster 54, the urging force by which the spring 110 presses the valve body 114A against the valve seat 39 can be adjusted.

  A cup-shaped housing 103 is fixed to the outer periphery of the large-diameter cylindrical portion 23 of the nozzle holder 101. A through hole is provided in the center of the bottom of the housing 103, and the large diameter cylindrical portion 23 of the nozzle holder 101 is inserted through the through hole. A portion of the outer peripheral wall of the housing 103 forms an outer peripheral yoke portion facing the outer peripheral surface of the large-diameter cylindrical portion 23 of the nozzle holder 101. An annular or cylindrical electromagnetic solenoid 105 is disposed in a cylindrical space formed by the housing 103. The electromagnetic solenoid 105 is formed of an annular bobbin 104 having a U-shaped groove that opens outward in the radial direction and a copper wire wound around the groove. A rigid conductor 109 is fixed to the winding start and winding end portions of the solenoid 105. The outer periphery of the large-diameter cylindrical portion 23 of the conductor 109, the stator 107, and the nozzle holder 101 is molded by injecting insulating resin from the inner periphery of the upper end opening of the housing 103, and is covered with the resin molded body 121. Thus, a toroidal magnetic path is formed around the electromagnetic solenoid (104, 105).

  A plug for supplying power from a high-voltage power source and a battery power source is connected to the connector 43A formed at the tip of the conductor 109, and energization and de-energization are controlled by a controller (not shown). While the solenoid 105 is energized, a magnetic attractive force is generated between the mover 102 and the stator 107 by the magnetic flux passing through the magnetic circuit, and the mover 102 exerts a biasing force of the spring 110 and a fluid force acting on the valve body tip 114B. It moves upward by being sucked with a force exceeding. At this time, the valve body 114 </ b> A is engaged with the movable element 102 by the stepped portion 129 and moves upward together, and moves until the upper end surface of the movable element 102 collides with the lower end surface of the stator 107. As a result, the front end portion 114B of the valve body is separated from the valve seat 39, and fuel is injected from the injection port 117 at the front end of the orifice cup 116 into the combustion chamber of the internal combustion engine.

  When the energization to the electromagnetic solenoid 105 is cut off, the magnetic flux in the magnetic circuit disappears and the magnetic attractive force in the gap 136 disappears. In this state, the urging force of the spring 110 that pushes the stepped portion 129 of the valve body 114A in the downstream direction overcomes the urging force of the zero spring 112 and acts on the valve body 114A and the movable element 102. As a result, the tip 114B of the valve body 114A is pushed back to the closed position where it contacts the valve seat 39. At this time, the stepped portion 129 comes into contact with the upper surface of the movable element 102 and moves the movable element 102 to the rod guide 113 side by overcoming the urging force of the zero spring 112. When the tip 114B of the valve body 114A collides with the valve seat, the mover 102 is separate from the valve body 114A, and therefore continues to move in the direction of the rod guide 113 due to inertial force. Since the movable element 102 having a large inertial mass is separated from the valve body 114A, the energy itself that the valve body 114A rebounds again from the valve seat 39 in the valve opening direction is reduced. Further, since the kinetic energy of the movable element 102 decreases due to fluid resistance with the surrounding fluid during movement and the repulsive force received after compressing the zero spring 112 is reduced, the movable element 102 itself rebounds and the valve element 114A The collision with the stepped portion 129 again causes the phenomenon that the valve element 114A is moved again in the valve opening direction. Thus, the rebound of the valve body 114A is minimized, and the so-called secondary injection phenomenon, in which the valve is opened after the energization of the electromagnetic solenoids (104, 105) is cut off and the fuel is randomly injected, is the conventional phenomenon. It was suppressed in the range of fuel injection pressure.

  Hereinafter, features of the present embodiment will be described.

  FIG. 2 is a partially enlarged view when the fuel injection valve is opened during energization. A magnetic attraction force is generated between the mover 102 and the stator 107, and the mover 102 moves upward by being attracted by a force that exceeds the biasing force of the spring 110 and the fluid force acting on the tip 114B of the valve body 114A. . At this time, the valve body 114 </ b> A is engaged with the movable element 102 by the stepped portion 129 and moves upward together, and moves until the upper end surface of the movable element 102 collides with the lower end surface of the stator 107. As a result, the front end portion 114B of the valve body is separated from the valve seat 39, and fuel is injected from the injection port 117 at the front end of the orifice cup 116 into the combustion chamber of the internal combustion engine. A mass damper 200 is disposed on the upstream side of the valve body 114A, and an elastic member 201 is disposed between the stopper 202 that is press-fitted and fixed in the through hole 107D of the stator 107. The mass damper 200 is kept in contact with the upper end surface of the spring guide projection 114C by the urging force of the elastic member 201. The urging force of the elastic member 201 is smaller than the urging force of the spring 110.

  FIG. 3 shows the moment when the magnetic attractive force disappears after the solenoid is energized and the tip 114B of the fuel injection valve body 114A collides with the valve seat 39 of the orifice cup 116. The biasing force of the spring 110 that presses the valve body 114A in the downstream direction is larger than the biasing force of the zero spring 112 that presses the movable element 112 in the upstream direction. Therefore, when the current to the solenoid 104 is interrupted, the magnetic attractive force that has lifted the movable element 102 toward the stator 107 disappears, and the valve body 114A is pushed down toward the orifice cup 116 by the biasing force of the spring 110. . The movable element 102 is engaged with the valve body 114A by the stepped portion 129 of the valve body 114A and moves downward together. The mass damper 200 is kept in contact with the upper end surface of the spring guide projection 114C by the urging force of the elastic member 201. The tip 114B collides with the valve seat 39 of the orifice cup 116, and a gap 136 exists between the upper end surface of the movable element 112 and the lower end surface of the stator 107.

  FIG. 4 is a partial enlarged view of the fuel injection valve when the valve body 114A receives the reaction of the impact force when it collides with the valve seat 39 of the orifice cup 116 immediately after FIG. The movable element 102 moves away from the stepped portion 129 of the valve body 114A and independently moves in the downstream direction by its own inertial force. Therefore, the mass of the movable element 102 is not taken into consideration to the impact force when it collides with the valve seat 39 of the orifice cup 116, and at the same time, it is not taken into consideration to the impact force as a reaction to the valve body 114A. Since the mass damper 200 is in contact with the upper end surface of the spring guide projection 114C of the valve body 114A, the mass damper 200 receives an impact force transmitted through the valve body 114A. The urging force of the elastic member 201 pressing the mass damper 200 against the upper end surface of the spring guide projection 114C is set smaller than the urging force of the spring 110 pressing the valve body 114A downstream. Therefore, the impact force that has propagated through the valve body 114A propagates to the mass damper 200 and then pushes the mass damper 200 in the upstream direction. In other words, the impact reaction force between the valve body 114A and the mass damper 200 is mainly converted into the kinetic energy of the mass damper, so that the valve body 114A itself is brought into contact with the valve seat 39 of the orifice cup 116 by the biasing force of the spring 110. Maintain contact.

  In this way, in order to convert the impact reaction force from the valve seat 39 of the orifice cup 116 into the kinetic energy of the mass damper 200 by utilizing the propagation of the impact force and maintain the stationary state of the valve body 114A, the mass damper 200 and the valve body. It is desirable that the material, mass, and shape of 114A be equal. On the other hand, since there are various restrictions on the internal structure of the fuel injection valve, if it cannot be equivalent, by setting the magnitude of the biasing force of the elastic member 201 to 10% or less of the biasing force of the spring 110, for example, The stationary state of the body 114A can be maintained.

  In the known conventional invention, the valve body cannot be prevented from being opened again by the impact force acting on the valve body from the valve seat. In this embodiment, a mass damper is arranged on the upper part of the valve body, and the mass damper is biased in the direction of the valve body with a biasing force smaller than the biasing force of the spring biasing the valve body in the valve closing direction. The present invention proposes a structure of a fuel injection valve in which the valve body does not open again due to an impact force acting on the valve body from the seat.

  As described above, in this embodiment, the impact force acting on the valve body from the valve seat is converted into the kinetic energy of the mass damper, so that the valve body is opened again more than in the prior art, and an extremely small amount of fuel is unintentionally generated. It can be prevented from being injected again.

  In addition, a present Example is not limited to the said embodiment. Moreover, each component is not limited to the said structure unless the characteristic function of a present Example is impaired.

  As an example, in the present embodiment, a mass damper is disposed on the upper portion of the valve body, but a similar mass damper can be disposed in contact with the inside of the valve body or at another position. This is because the present embodiment is based on the viewpoint of propagation of impact force, the biasing direction of the elastic member, and the magnitude relationship. Even if the mass damper is arranged at any position, the principle of the present embodiment can be applied as long as the positional relationship between the valve body and the mass damper capable of propagating the impact reaction force is effective.

22 ... Nozzle holder small diameter cylindrical portion 23 ... Nozzle holder large diameter cylindrical portion 39 ... Valve seat 43A ... Connector 101 ... Nozzle holder 102 ... Movable element 103 ... Housing 104 ... Bobbin 105 ... Solenoid 107 ... Stator 107D ... Stator penetration Hole (fuel passage)
109 ... Conductor 110 ... Spring 112 ... Zero spring 113 ... Shoulder 114A ... Valve body 114B ... Valve body tip 114C ... Spring guide projection 115 ... Guide portion 116 ... Orifice cup 117 ... Fuel injection port 121 ... Resin molded body 126 ... Fuel passage 128 ... through hole 136 ... gap 200 ... mass damper 201 ... elastic member 202 ... stopper

Claims (3)

Magnetic attraction by energizing the stator, a solenoid disposed on the outer peripheral side of the stator, a mover facing the lower end of the stator, a valve element engaged with the mover, and the solenoid A force is generated so that the movable element is sucked into the stator, and the valve body is opened. The valve body is urged in a closing direction by a first elastic member, and the movable element is In the fuel injection valve urged in the release direction by the elastic member of
A fuel injection valve, comprising: a mass damper that contacts the valve body; and a third elastic member that biases the mass damper in a closing direction.   2. The fuel injection valve according to claim 1, wherein the urging force of the first elastic member is smaller than the urging force of the third elastic member.   The fuel injection valve according to claim 1 or 2, wherein a mass damper has a mass substantially equal to that of the valve body.