JP4609351B2 - Injector - Google Patents

Description

  The present invention relates to an injector that receives fuel from a predetermined fuel supply source and injects it into an engine.

  2. Description of the Related Art Conventionally, an injector is mounted on a direct injection type engine such as a diesel engine, and is used to receive fuel from a fuel supply source such as a common rail and directly inject and supply it into a cylinder. This injector includes a needle that opens and closes a nozzle hole provided at the tip, and lifts the needle in the axial direction by guiding fuel so as to apply pressure to the needle in the direction of opening the nozzle hole (valve opening direction). Let the nozzle hole open.

  In recent years, in order to further increase the combustion efficiency by further atomizing the fuel spray injected from the injector, the fuel injection pressure by the injector has been increased. In addition to simply increasing the fuel supply pressure in the fuel supply source, studies are underway to increase pressure more positively by providing a pressure increasing mechanism in the injector.

  For example, the pressure increasing mechanism includes a pressure increasing piston having a pressure increasing surface on which a fuel as a pressure increasing medium exerts pressure, and a pressure increasing surface that exerts pressure on the fuel to be increased. The pressure of the fuel is increased according to the area ratio (see, for example, Patent Document 1). The increased fuel is guided to exert pressure on the needle in the valve opening direction, lifts the needle, and is injected and atomized from the opened nozzle hole (that is, in the valve opening direction with respect to the needle). The pressure of the working fuel corresponds to the injection pressure).

However, the higher the injection pressure, the stronger the needle at the time of valve opening receives pressure in the valve opening direction. For this reason, when it is necessary to shorten the opening period of the nozzle hole as in the case of micro injection, it is difficult to quickly stop the needle lift and to lower the needle to the nozzle hole side. As a result, when a small amount of fuel injection is required, fuel that is always larger than the target amount is injected, which may cause deterioration of fuel consumption, increase in smoke, and the like.
WO05 / 015000 pamphlet

  The present invention has been made to solve the above-described problems, and an object of the present invention is to make it possible to perform a micro injection by an injector with high accuracy even when the injection pressure is high.

[Means of Claim 1]
The injector according to claim 1 includes a needle that opens and closes a nozzle hole provided at a tip, and guides fuel so as to apply pressure to the needle in a valve opening direction, whereby the needle is lifted in an axial direction and the nozzle hole Is released.
The injector includes a needle interlocking member that is provided on the rear end side of the nozzle hole and is disposed in a fuel chamber in which fuel flows, and interlocks with the needle when the needle is lifted. When the needle is lifted from the fully closed state, the injector has a squeeze force of a predetermined strength or more between the tip end member surface of the needle interlocking member and the tip end wall surface forming the fuel chamber. The gap in the lift direction in the fully closed state between the tip-side member surface and the tip-side wall surface, and the effective diameter of the surface facing the tip-side wall surface in the tip-side member surface are set to occur. Yes.

Thereby, when the needle is lifted, the needle interlocking member receives a squeeze force of a predetermined strength or more in a direction in which the needle interlocking member is prevented from separating from the wall surface on the distal end side. That is, the squeeze force acts on the needle interlocking member in the direction opposite to the needle lift direction (that is, the valve opening direction) (the valve closing direction: the direction in which the nozzle hole is closed). For this reason, the needle interlocked with the needle interlocking member is also urged in the valve closing direction by transmitting this squeeze force. As a result, the urging force acting on the needle in the valve opening direction is weakened, so that the needle lift speed is reduced.
As described above, even if the injection pressure is high, a minute amount of injection by the injector can be performed with high accuracy.

Further, according to the injector of claim 1, the needle is provided continuously with the non-binding portion that allows movement of the needle interlocking member in the valve opening direction, and the distal end side of the non-binding portion. has an engaging portion which engages the distal end side, the needle interlocking member is in engagement with the engaging portion is biased distally by a predetermined biasing means are assembled to the needle, the needle When the needle moves in the valve closing direction, the needle connecting member moves away from the engaging portion.

A squeeze force is generated between the member surface on the distal end side and the wall surface on the distal end side not only when the needle is lifted but also when the needle is lowered. The squeeze force at the time of lowering acts on the needle interlocking member in the direction opposite to the squeeze force at the time of lift (that is, the valve opening direction). For this reason, when this squeeze force is transmitted to the needle at the time of lowering, the needle is urged in the valve opening direction to prevent the lowering.

On the other hand, according to the above configuration, the squeeze force acting in the valve opening direction is not transmitted to the needle. Furthermore, the needle interlocking member can be disengaged from the engaging portion and freely displaced toward the rear end side (that is, in the valve opening direction) by a squeeze force acting in the valve opening direction. For this reason, the needle can be lowered without being obstructed by the squeeze force acting in the valve opening direction.

Furthermore, according to said structure, the squeeze force at the time of the lift which acts on a valve closing direction is reliably transmitted to a needle from a needle interlocking member by engagement with a needle interlocking member and an engaging part. For this reason, the lift speed of the needle is reliably reduced by the squeeze force acting in the valve closing direction.

[Means of claim 2]
  According to the injector of the second aspect, the fuel chamber is provided so as to be biased to one side with respect to the axial center of the needle, and the needle interlocking member is assembled to the needle so as to be biased to the same side as the fuel chamber. .
  As a result, the effective diameter of the facing surface necessary for generating a squeeze force of a predetermined strength or more can be ensured reliably, and the fuel chamber is provided on the opposite side to the one side, A margin area that can be processed can be created. For this reason, a fuel flow path or the like can be provided in this marginal area.

[Means of claim 3]
  According to the injector of the third aspect, the fuel flow path is provided on the opposite side of the one side where the fuel chamber is provided, and the fuel flow path guides the fuel that exerts pressure in the valve opening direction on the needle. .
  This means discloses providing a fuel flow path in the marginal area. According to this means, the fuel flow path provided in the margin region guides the fuel that exerts pressure on the needle in the valve opening direction.

The injector of the best mode 1 includes a needle that opens and closes a nozzle hole provided at the tip, and guides fuel so as to apply pressure to the needle in the valve opening direction, thereby lifting the needle in the axial direction and opening the nozzle hole. Open.
The injector includes a needle interlocking member that is provided on the rear end side of the nozzle hole and is disposed in a fuel chamber in which fuel flows, and interlocks with the needle when the needle is lifted. When the needle is lifted from the fully closed state, the injector has a squeeze force of a predetermined strength or more between the tip end member surface of the needle interlocking member and the tip end wall surface forming the fuel chamber. The gap in the lift direction in the fully closed state between the tip-side member surface and the tip-side wall surface, and the effective diameter of the surface facing the tip-side wall surface in the tip-side member surface are set to occur. Yes.

  Further, according to this injector, the fuel chamber is provided so as to be biased to one side with respect to the axial center of the needle, and the needle interlocking member is assembled to the needle so as to be biased to the same side as the fuel chamber. Further, according to this injector, the fuel flow path is provided on the opposite side of the one side where the fuel chamber is provided, and this fuel flow path guides the fuel that exerts pressure on the needle in the valve opening direction.

Further, according to this injector, the needle is provided continuously from the unbound portion allowing the movement of the needle interlocking member in the valve opening direction and the distal end side of the unbound portion, and is engaged with the needle interlocking member from the distal end side. The needle interlocking member is assembled to the needle in a state where the needle interlocking member is urged toward the distal end side by the predetermined urging means and engaged with the engagement portion, and the needle is in the valve closing direction. When moving, the needle connecting member moves away from the engaging portion.

[Configuration of Example 1]
The structure of the injector 1 of Example 1 is demonstrated using FIG. 1 thru | or FIG.
For example, the injector 1 injects and supplies fuel to an engine (not shown) together with a fuel supply pump (not shown) for increasing the pressure of the fuel, a common rail for accumulating the fuel increased in pressure by the fuel supply pump in a high pressure state, and the like. An accumulator fuel injection device is configured. The injector 1 is mounted on the engine and injects fuel into the cylinder.

  The injector 1 includes, for example, a pressure-increasing mechanism 2 that increases the pressure of fuel received from a common rail, a nozzle 3 that is attached to the tip side of the pressure-increasing mechanism 2 and receives and injects the increased pressure, and a pressure-increasing mechanism 2. And an electromagnetic actuator 4 to be driven.

  The pressure-increasing mechanism 2 increases the fuel to be injected in accordance with the area ratio between the effective pressure increasing surface on which the fuel as the pressure increasing medium exerts pressure and the effective pressure increasing surface on which the pressure is increased. It is. That is, the pressure increasing mechanism 2 increases the pressure of the injected fuel by forming the effective pressure increasing surface in a larger area than the effective pressure increasing surface. The pressure increasing mechanism 2 includes a pressure increasing piston 6 having an effective pressure increasing surface on the front end side and an effective pressure increasing surface on the rear end side, and a control valve 7 for driving the pressure increasing piston 6.

  The pressure-increasing piston 6 is accommodated in a partially sliding manner in a cylinder provided so as to increase in diameter toward the rear end side. That is, the pressure-increasing piston 6 is provided so as to be in sliding contact with the cylinder at least at two positions, the front end side and the rear end side, so that the portion slidably contacting on the front end side is smaller in diameter than the portion slidably contacting on the rear end side. Yes. Thereby, the pressure increasing piston 6 can form an effective pressure increasing surface on the front end side and an effective pressure increasing surface having a larger area than the effective pressure increasing surface on the rear end side.

  The pressure-increasing piston 6 is housed in the cylinder as described above, so that the pressure-increasing chamber 8 into which fuel as a pressure-increasing medium flows in and out, and the pressure-increasing chamber into which the pressure-increasing fuel flows in and out. 9 and a pressure increase control chamber 10 through which fuel for controlling the pressure increase state flows in and out.

  The pressure increasing chamber 8 communicates with the common rail by the fuel flow path 12 and receives high-pressure fuel as a pressure increasing medium. Further, in the pressure increasing chamber 8, an effective pressure increasing surface is formed by projecting the rear portion of the pressure increasing piston 6. The pressure increasing chamber 8 accommodates a restoring spring 13 of the pressure increasing piston 6. The restoring spring 13 moves the pressure increasing piston 6 to the rear end side (that is, the direction in which the pressure increasing chamber 9 expands). In other words, the pressure is applied in the direction of reducing the pressure in the pressurized chamber 9.

The pressurized chamber 9 receives high-pressure fuel from the pressurized chamber 8 through the fuel flow path 14 provided in the pressurized piston 6. Moreover, the increasing chamber 9, so that the tip end surface of the booster piston 6 form an effective target increasing pressure surface is blocked from the rear side by the front part of the boosting piston 6. Note that a check valve 15 is disposed in the fuel flow path 14 to prevent the fuel whose pressure has been increased in the pressurized chamber 9 from flowing into the pressurized chamber 8.

  The pressure-increasing control chamber 10 is provided between the effective pressure-increasing surface and the effective pressure-increasing surface, and the fuel in the pressure-increasing control chamber 10 is a pressure-increasing piston according to the area difference between the effective pressure-increasing surface and the effective pressure-increasing surface. 6 is urged toward the rear end. That is, the pressure in the pressure increase control chamber 10 acts in a direction to reduce the pressure in the pressure increase chamber 9 with respect to the pressure increase piston 6.

  Here, the pressure increase control chamber 10 communicates with a control valve chamber 18 that accommodates the control valve 7 via the fuel flow path 16, and communicates with a fuel tank or a common rail depending on the position of the control valve 7. Or communicates with the pressure increasing chamber 8 leading to. As a result, the pressure in the pressure increase control chamber 10 is increased or decreased, and the pressure increasing piston 6 is displaced to the rear end side or the front end side. As a result, the fuel flows into and out of the pressure increasing chamber 8, and the pressure in the pressure increasing chamber 9 is controlled.

  The control valve 7 is housed in a control valve chamber 18 in which a fuel flow path 16 communicating with the pressure increase control chamber 10, a fuel flow path 19 communicating with the fuel tank, and a fuel flow path 20 communicating with the pressure increase chamber 8 are opened. The control valve 7 has an open state in which the fuel flow path 16 and the fuel flow path 19 communicate with each other and fuel flows out from the pressure increase control chamber 10 to the fuel tank, and the fuel flow path 16 and the fuel flow path 20 communicate with each other. It functions as a three-way valve that switches between a closed state in which fuel flows into the pressure increase control chamber 10 from the common rail via the pressure increase chamber 8.

  That is, the control valve 7 includes a high pressure side valve portion 22 that opens and closes between the fuel flow path 16 and the fuel flow path 20, a low pressure side valve portion 23 that opens and closes between the fuel flow path 16 and the fuel flow path 19, and It has a piston part 24 that receives a control pressure for driving the control valve 7. Here, the control pressure is the pressure in the control chamber 25 formed by sealing the rear end portion of the control valve chamber 18 by the piston portion 24. A fuel flow path 27 connected to the fuel flow path 19 and a fuel flow path 28 communicating with the pressure increasing chamber 8 are opened in the control chamber 25. In addition, the electromagnetic actuator 4 is disposed in the fuel flow path 27 and a throttle 29 is formed, and a throttle 30 is formed in the fuel flow path 28.

  When the electromagnetic actuator 4 is operated, the fuel flow path 27 is opened to allow communication between the control chamber 25 and the fuel flow path 19. Here, the throttles 29 and 30 are configured so that the flow rate of the fuel flowing out from the control chamber 25 to the fuel flow path 19 through the fuel flow path 27 is the amount of fuel flowing into the control chamber 25 from the pressure increasing chamber 8 via the fuel flow path 28. It is provided to be larger than the flow rate.

  For this reason, when the electromagnetic actuator 4 is operated, the pressure in the control chamber 25 is reduced, so that the control valve 7 is displaced from the closed position to the open position. As a result, fuel flows out from the pressure increase control chamber 10 to the fuel tank through the fuel flow path 16, the control valve chamber 18 and the fuel flow path 19, and the pressure in the pressure increase control chamber 10 is reduced. As a result, the pressure-increasing piston 6 is displaced to the front end side, fuel flows from the common rail into the pressure-increasing chamber 8 via the fuel flow path 12, and the fuel in the pressure-increasing chamber 9 is increased.

  When the electromagnetic actuator 4 stops operating, the fuel flow path 27 is closed, so that the flow of fuel from the control chamber 25 stops and only the flow of fuel from the fuel flow path 28 to the control chamber 25 continues. Therefore, when the electromagnetic actuator 4 stops operating, the pressure in the control chamber 25 is increased, and the control valve 7 is displaced from the open position to the closed position.

  As a result, high-pressure fuel flows from the common rail into the pressure increase control chamber 10 through the fuel flow path 12, the pressure increase chamber 8, the fuel flow path 20, the control valve chamber 18 and the fuel flow path 16. The pressure is increased. As a result, the pressure-increasing piston 6 is displaced to the rear end side, the pressure in the pressure-increasing chamber 9 is reduced, and fuel flows from the pressure-increasing chamber 8 into the pressure-increasing chamber 9 through the fuel flow path 14.

  The nozzle 3 includes a needle 33 that opens and closes a nozzle hole 32 provided at the tip. The needle 33 opens and closes the nozzle hole 32 by repeating the seating and separation between the seat part 34 provided at the tip part and the seat surface 35.

  Further, the nozzle 3 is pressurized in a direction (valve closing direction) for closing the nozzle hole 32 with respect to the nozzle chamber 37 and the needle 33 in which the fuel that exerts pressure flows in and out of the nozzle hole 32 (valve opening direction). A back pressure chamber 38 is formed to flow in and out of the fuel. The needle 33 is urged in the valve closing direction by the pressure in the back pressure chamber 38 and the restoring spring 39, and is urged in the valve opening direction by the pressure in the nozzle chamber 37.

  Here, the nozzle chamber 37 communicates with the pressurized chamber 9 through the fuel flow path 40, and the back pressure chamber 38 communicates with the pressure increase control chamber 10 through the fuel flow path 41. The fuel flow path 41 is provided with a throttle 43 and a bypass flow path that leads to the back pressure chamber 38 in parallel with the throttle 43, and pressure increase control from the back pressure chamber 38 is provided in this bypass flow path. A check valve 44 that prevents backflow into the chamber 10 is disposed. Furthermore, in order to collect the fuel leaked from the nozzle chamber 37 and the back pressure chamber 38 in the fuel tank, a fuel channel 45 is provided and communicates with the fuel channel 19.

  As a result, when the electromagnetic actuator 4 is actuated and pressure is increased by the pressure-increasing mechanism 2, the fuel increased in pressure from the pressure-increasing chamber 9 flows into the nozzle chamber 37 via the fuel flow path 40. At the same time, the fuel in the back pressure chamber 38 flows out to the fuel tank through the fuel flow path 41, the pressure increase control chamber 10, the fuel flow path 16, the control valve chamber 18 and the fuel flow path 19.

  As a result, the pressure in the nozzle chamber 37 is increased and the pressure in the back pressure chamber 38 is reduced, so that the urging force acting on the needle 33 in the valve opening direction acts on the needle 33 in the valve closing direction. It becomes stronger than the urging force, the needle 33 is lifted and the nozzle hole 32 is opened. In the fuel flow path 41, the fuel flows from the back pressure chamber 38 toward the pressure increase control chamber 10, so the check valve 44 is closed. For this reason, the outflow rate from the back pressure chamber 38 is regulated by the throttle 43.

  Further, when the electromagnetic actuator 4 stops operating and pressure increase by the pressure increase mechanism 2 is not performed, the increased fuel does not flow into the nozzle chamber 37. At the same time, the high pressure fuel is supplied from the common rail through the fuel flow path 12, the pressure increasing chamber 8, the fuel flow path 20, the control valve chamber 18, the fuel flow path 16, the pressure increasing control chamber 10 and the fuel flow path 41. It flows into the chamber 38.

  As a result, the pressure in the nozzle chamber 37 is reduced and the pressure in the back pressure chamber 38 is increased, so that the biasing force acting on the needle 33 in the valve closing direction acts on the needle 33 in the valve opening direction. It becomes stronger than the urging force, the needle 33 is lowered and the nozzle hole 32 is closed. In the fuel flow path 41, the fuel flows from the pressure increase control chamber 10 toward the back pressure chamber 38, so the check valve 44 is opened. For this reason, since the inflow flow rate to the back pressure chamber 38 is not regulated by the throttle 43, the pressure in the back pressure chamber 38 is quickly increased.

  Further, as shown in FIG. 2, the nozzle 3 includes a needle interlocking member 47 that interlocks with the needle 33 when the needle 33 lifts. And since the needle interlocking member 47 needs to generate a squeeze force having a predetermined strength or more, the back pressure chamber 38, which is one of the fuel chambers provided on the rear end side of the nozzle hole 32 and in which the fuel flows, is provided. Is arranged.

  The needle 33 is continuously provided on the distal end side of the unbound portion 48 that allows the needle interlocking member 47 to move in the valve opening direction, and is engaged with the needle interlocking member 47 from the distal end side. The needle interlocking member 47 is assembled to the needle 33 in a state where the needle interlocking member 47 is urged toward the distal end side by a predetermined restoring spring 50 and engaged with the engaging portion 49.

  That is, the rear end portion of the needle 33 is disposed so as to protrude into the back pressure chamber 38, and the unbound portion 48 and the engaging portion 49 are provided at the rear end portion of the needle 33. The unbound portion 48 and the engaging portion 49 are provided by reducing the diameter of the rear end portion of the needle 33 by a predetermined length in the axial direction. On the other hand, the needle interlocking member 47 is provided with a hole having a diameter larger than that of the unbound portion 48, and the unbound portion 48 is loosely inserted into the hole.

  Here, when the needle 33 is lifted, the squeeze force is such that the distal end side member surface (front end side member surface) 52 of the needle interlocking member 47 and the distal end side wall surface (front end side wall surface) 53 that forms the back pressure chamber 38. Occurs between. This squeeze force acts in a direction that prevents the needle interlocking member 47 from being engaged with the engaging portion 49 and lifting together with the needle 33 (ie, the valve closing direction) when the needle 33 is lifted.

  The needle interlocking member 47 is provided and arranged so that the squeeze force becomes a predetermined strength or more when the needle 33 is lifted from the fully closed state. That is, the lift direction clearance (valve at the time of valve closing) in the fully closed state between the distal end side member surface 52 and the distal end side wall surface 53 and the distal end side member surface 52 so that the squeeze force becomes a predetermined strength or more. The effective diameter (opposing surface effective diameter) of the opposing surface to the front end side wall surface 53 is set.

Here, the predetermined strength of the squeeze force, the clearance during valve closing, and the effective diameter of the facing surface can be obtained, for example, as follows.
First, when the squeeze force is expressed as Fsq, the lift speed of the needle 33 is expressed as V, the gap between the tip side member surface 52 and the tip side wall surface 53 is expressed as h, and the opposing surface effective diameter is expressed as r, the squeeze force Fsq is expressed as As expressed by Equation 1, it is expressed as a function of the lift speed V, the gap h, and the opposed surface effective diameter r.
[Formula 1]
Fsq = Fsq (V, h, r)

  Here, since the purpose of generating the squeeze force Fsq is to perform micro injection with high accuracy, the target value of the lift amount L of the needle 33 when performing micro injection is La, and the lift amount L is the target value La. Let Va be the target value of the lift speed V when it reaches. If the initial value of the gap h (that is, the valve closing gap) is h0, the gap h when the lift amount L reaches the target value La is h0 + La as shown in FIG.

When the lift amount L reaches the target value La, the urging force F acting on the needle 33 in the valve opening direction substantially coincides with the squeeze force Fsq acting on the valve closing direction. The target value Va, the valve closing clearance h0, the target value La, and the opposed surface effective diameter r are obtained so as to satisfy Formula 2.
[Formula 2]
F = Fsq (Va, h0 + La, r)

  The urging force F includes the pressure of the back pressure chamber 38, the effective pressure receiving area of the pressure of the back pressure chamber 38 received by the needle 33, the pressure of the nozzle chamber 37, the effective pressure receiving area of the pressure of the nozzle chamber 37 received by the needle 33, and the restoration. It can be determined based on the urging force of the spring 39, inertial force, fluid drag force other than the squeeze force Fsq, and the like. The pressure in the back pressure chamber 38 and the pressure in the nozzle chamber 37 can be determined according to the fuel pressure in the common rail, the area ratio between the effective pressure increasing surface and the effective pressure increasing surface, and the like.

  As described above, the valve closing clearance h0 and the opposing surface effective diameter r are obtained, and further, the target value Va, the valve closing clearance h0, the target value La, and the opposing surface effective diameter r are applied to the right side of Equation 2 to obtain the squeeze. A predetermined strength of the force Fsq can be obtained.

  The change over time in the lift amount L changes, for example, as shown in FIG. 3B due to the action of the squeeze force Fsq corresponding to the valve closing gap h0 and the opposed surface effective diameter r (in the figure, t is Time). As a result, the lift speed V (that is, dL / dt) decreases, and the time t for the lift amount L to reach the target value La increases.

  The back pressure chamber 38 is provided so as to be biased to one side with respect to the axial center of the needle 33, and the needle interlocking member 47 is eccentric to the needle 33 so as to be biased to the same side as the back pressure chamber 38. It is assembled. As a result, the opposing surface effective diameter r necessary to generate the squeeze force Fsq of a predetermined strength or more is ensured, and the back pressure chamber 38 is provided on the opposite side to the one side, There is a margin area that can be processed. A fuel flow path 40 that communicates the pressurized chamber 9 and the nozzle chamber 37 is provided in this marginal area.

[Operation of Example 1]
The operation of the injector 1 according to the first embodiment will be described.
First, when the electromagnetic actuator 4 is activated and the fuel whose pressure is increased flows into the nozzle chamber 37, the needle 33 starts to lift. The needle interlocking member 47 is engaged with the engaging portion 49 and starts moving in the valve opening direction together with the needle 33.

  At this time, a squeeze force Fsq acts between the distal end side member surface 52 and the distal end side wall surface 53, and this squeeze force Fsq acts on the needle interlocking member 47 in the valve closing direction. The squeeze force Fsq is transmitted from the needle interlocking member 47 to the needle 33 by the engagement of the needle interlocking member 47 and the engaging portion 49. For this reason, the lift speed V is reduced by the squeeze force Fsq acting in the valve closing direction.

  Eventually, when the electromagnetic actuator 4 stops operating and the fuel whose pressure is increased does not flow into the nozzle chamber 37, the needle 33 starts to descend. Even when the squeeze force Fsq is lowered, the squeeze force Fsq acts between the distal end side member surface 52 and the distal end side wall surface 53, but the squeeze force Fsq acts upon the needle interlocking member 47 in the valve opening direction.

  For this reason, the squeeze force Fsq is not transmitted from the needle interlocking member 47 to the needle 33. Further, by this squeeze force Fsq, the needle interlocking member 47 is detached from the engaging portion 49 and freely displaced to the rear end side. As a result, the needle 33 moves down without being affected by the squeeze force Fsq.

[Effect of Example 1]
According to the injector 1 of the first embodiment, the needle interlocking member 47 that interlocks with the needle 33 when the needle 33 lifts is disposed in the back pressure chamber 38. When the needle 33 is lifted, the valve-closing gap h0 and the opposing surface effective diameter are set so that a squeeze force Fsq of a predetermined strength or more is generated between the tip side member surface 52 and the tip side wall surface 53. r is set.
Thereby, when the needle 33 lifts, the needle interlocking member 47 receives a squeeze force Fsq of a predetermined strength or more in the valve closing direction. For this reason, the needle 33 interlocked with the needle interlocking member 47 is also urged in the valve closing direction by transmitting the squeeze force Fsq. As a result, since the urging force acting in the valve opening direction on the needle 33 is weakened, the lift speed V of the needle 33 is reduced. As described above, even when the injection pressure is high, it is possible to perform a minute amount of injection with high accuracy.

The back pressure chamber 38 is provided so as to be biased to one side with respect to the axial center of the needle 33, and the needle interlocking member 47 is assembled to the needle 33 so as to be biased to the same side as the back pressure chamber 38.
Thus, the effective diameter r of the facing surface necessary for generating the squeeze force Fsq of a predetermined strength or more can be ensured, and the back pressure chamber 38 is provided on the opposite side of the one side. In addition, it is possible to create a marginal area that can be processed. For this reason, the fuel flow path 40 can be provided in this marginal area.

The needle 33 is continuously provided on the distal end side of the unbound portion 48 that allows the needle interlocking member 47 to move in the valve opening direction, and is engaged with the needle interlocking member 47 from the distal end side. The needle interlocking member 47 is assembled to the needle 33 in a state in which the needle interlocking member 47 is urged toward the distal end side by the restoring spring 50 and engaged with the engaging portion 49.
Thereby, when the squeeze force Fsq acts in the valve opening direction (that is, when the needle 33 is lowered), the squeeze force Fsq is not transmitted to the needle 33. Furthermore, when the squeeze force Fsq acts in the valve opening direction, the needle interlocking member 47 can be disengaged from the engaging portion 49 by the squeeze force Fsq and can be freely displaced toward the rear end side (that is, in the valve opening direction). For this reason, the needle 33 can be lowered without being obstructed by the squeeze force Fsq acting in the valve opening direction.
Further, when the squeeze force Fsq acts in the valve closing direction (that is, when the needle 33 is lifted), the squeeze force Fsq is reliably connected to the needle interlocking member 47 by the engagement of the needle interlocking member 47 and the engaging portion 49. To the needle 33. For this reason, the lift speed V of the needle 33 is reliably reduced by the squeeze force Fsq acting in the valve closing direction.

[Modification]
According to the injector 1 of the first embodiment, the fuel chamber in which the needle interlocking member 47 is disposed is the back pressure chamber 38. However, the needle interlocking member 47 may be disposed in the nozzle chamber 37, and the restoring spring 39 is provided. You may arrange | position in the spring chamber to accommodate. When the injector 1 has a command piston on the rear end side of the needle 33 and the back pressure chamber 38 is formed on the rear end of the command piston, the needle interlocking member 47 may be assembled to the command piston.

It is explanatory drawing which shows the structure of an injector. It is explanatory drawing which shows the principal part structure of an injector. (A) is explanatory drawing which shows the setting item for determining squeeze force, (b) is explanatory drawing which shows the influence on the lift speed by squeeze force.

Explanation of symbols

1 Injector 32 Injection hole 33 Needle 38 Back pressure chamber (fuel chamber)
40 Fuel channel 47 Needle interlocking member 48 Non-binding part 49 Engaging part 50 Restoring spring (predetermined biasing means)
52 Tip side member surface (tip side member surface)
53 Side wall of the tip (wall on the tip side)
Fsq Squeeze force h0 Valve closing clearance (valve closing between the tip member surface and the tip wall)
r Effective diameter of facing surface (effective diameter of the facing surface of the member surface on the leading end side with the wall surface on the leading end side)

Claims (3)

Provided with a needle that opens and closes the nozzle hole provided at the tip,
In the injector that lifts the needle in the axial direction and opens the nozzle hole by guiding the fuel so as to exert pressure on the needle in the valve opening direction,
A needle interlocking member that is provided on the rear end side of the nozzle hole and disposed in a fuel chamber in which fuel flows, and interlocks with the needle when the needle lifts;
When the needle is lifted from the fully closed state, a squeeze force having a predetermined strength or more is generated between a member surface on the distal end side of the needle interlocking member and a wall surface on the distal end side forming the fuel chamber. In addition, a clearance in the lift direction in the fully closed state between the tip-side member surface and the tip-side wall surface, and an effective diameter of the surface of the tip-side member surface facing the tip-side wall surface are set. ,
The needle includes a non-binding portion that allows movement of the needle interlocking member in the valve opening direction, and an engagement that is provided continuously from the distal end side of the unconstrained portion and engages the needle interlocking member from the distal end side. Part
The needle interlocking member is assembled to the needle in a state where the needle interlocking member is urged toward the distal end side by a predetermined urging means and is engaged with the engagement portion ,
The injector, wherein the needle connecting member moves away from the engaging portion when the needle moves in a valve closing direction . The injector according to claim 1, wherein
The fuel chamber is provided so as to be biased to one side with respect to the axis of the needle,
The injector, wherein the needle interlocking member is assembled to the needle so as to be biased to the same side as the fuel chamber. Injector according to claim 2,
A fuel flow path is provided on the opposite side of the one side where the fuel chamber is provided,
The fuel flow path guides fuel that exerts pressure on the needle in a valve opening direction .

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