JP7171448B2 - fuel injector - Google Patents

Description

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

In recent years, the number of fuel injection valves equipped with a preliminary stroke mechanism has been increasing in order to cope with demands for higher speed and higher fuel pressure. A typical fuel injection valve has a structure in which a movable element positioned in a valve closed state by a first spring is attracted by an electromagnet. The mover consists of an anchor that generates force according to the magnetic flux produced by the electromagnet, and a plunger rod that is driven by the anchor and has a valve structure at its end. The reserve stroke is the space (play) provided between the anchor and the plunger rod.

The fuel injection valve equipped with a preliminary stroke mechanism has a structure that is less likely to receive the reaction force from the plunger rod while the anchor is moving through the preliminary stroke due to the electromagnetic force acting on it. can impact the plunger rod. Therefore, in the fuel injection valve provided with the preliminary stroke mechanism, not only the electromagnetic energy acting on the anchor but also the kinetic energy of the anchor contribute to the acceleration of the plunger rod, making it possible to open the valve at high speed. On the other hand, in a valve structure in which fuel pressure acts on the plunger rod (a structure that receives reaction force from the plunger rod), it is necessary to apply energy to the plunger rod to open the valve against the fuel pressure when the valve is opened. It can be said that a valve structure having a stroke is suitable for high fuel pressure.

For example, International Publication No. 2016/042896 pamphlet (Patent Document 1) discloses a fuel injection valve equipped with a preliminary stroke mechanism. is ensured. The spring force of the third spring that supports the intermediate member from the plunger rod is set to be greater than the spring force of the first spring that presses the plunger rod in the valve closing direction and greater than the spring force of the second spring that presses the anchor against the plunger rod. This enables high-speed operation while suppressing secondary injection due to anchor vibration.

Further, for example, in Japanese Patent Application Laid-Open No. 2014-208998 (Patent Document 2), the plunger rod and the movable plate (corresponding to the intermediate member of Patent Document 1) are moved to the valve closing side by using the first spring without using the third spring. A preliminary stroke similar to that of Patent Document 1 is ensured with a structure that presses against.

International Publication No. 2016/042896 Pamphlet JP 2014-208998 A

In order to handle high speed and high fuel pressure, it is necessary to increase the driving force (or moving speed) of the anchor by strengthening the electromagnetic force. There are concerns about the occurrence of an overshoot in which the anchor jumps up in the valve-opening direction together with the intermediate member (movable plate), and the occurrence of an undershoot in which the anchor largely sinks in the valve-closing direction when the valve is closed. If overshoot or undershoot occurs, not only will the injection characteristics be adversely affected by the secondary injection, etc., but also the intermediate member and the anchor that have once separated due to overshoot or undershoot will contact again, causing wear and tear on the intermediate member. Deformation is a concern.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection valve capable of suppressing overshoot and undershoot.

In order to achieve the above object, the fuel injection valve of the present invention comprises:
A plunger rod having a valve body provided at its tip, an anchor provided to be relatively displaceable in the axial direction with respect to the plunger rod, and an intermediate member interposed between the plunger rod and the anchor ,
The plunger rod has a stepped portion that engages with the anchor to restrict the relative displacement of the anchor when the anchor is displaced relative to the plunger rod in the valve opening direction,
When the valve is closed, the plunger rod , the anchor, and the intermediate member engage the stepped portion and the anchor that engages the stepped portion by abutting the anchor and the intermediate member in the axial direction. In a fuel injection valve in which an axial gap is formed between the
a first sliding portion in which the plunger rod and the anchor slide axially; a second sliding portion in which the stepped portion and the intermediate member slide axially; and the anchor and the intermediate member and a third sliding portion that slides in the axial direction,
A first minute gap formed in the first sliding portion and a second minute gap formed in the second sliding portion are connected to a closed space surrounded by the plunger rod, the anchor and the intermediate member,
The third minute gap formed in the third sliding portion is formed by releasing the contact between the anchor and the intermediate member in the axial direction during the valve opening operation and the valve closing operation. , is connected to a closed space surrounded by the anchor and the intermediate member, the first sliding portion constitutes a guide portion that guides the axial movement of the plunger rod,
The interval dimension of the second micro-gap and the interval dimension of the third micro-gap are equal to or less than the interval dimension of the first micro-gap .

According to the present invention, the expansion and contraction of the volume of the space surrounded by the anchor, plunger rod, and intermediate member is inhibited by increasing the fluid resistance when fuel flows into and out of the space surrounded by the anchor, plunger rod, and intermediate member. As a result, the occurrence of overshoot and undershoot can be suppressed, and wear and deformation of the intermediate member due to re-contact between the anchor and the intermediate member can be suppressed. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a cross-sectional view parallel to a central axis 100a showing the structure of a fuel injection valve 100 according to an embodiment of the present invention; FIG. FIG. 2 is a partially enlarged view (sectional view) showing the vicinity of the anchor 102 of FIG. 1; FIG. 3 is a partially enlarged view (cross-sectional view) further enlarging the vicinity of an intermediate member 133 of FIG. 2; FIG. 3 is a cross-sectional view similar to FIG. 2 showing the state of the mover 114 during the valve opening operation; FIG. 3 is a cross-sectional view similar to FIG. 2 showing a state in which the anchor 102 has collided with the stationary core 107; 3 is a cross-sectional view similar to FIG. 2 showing an overshoot condition in which plunger rod 114A separates from anchor 102 and operates alone; FIG. FIG. 3 is a cross-sectional view similar to FIG. 2 showing an undershoot condition in which anchor 102 separates from stepped portion 129 of plunger rod 114A and operates alone; FIG. 5 is an explanatory diagram comparing features of an embodiment according to the present invention with a comparative example in opening and closing valve operations of an anchor 102, a plunger rod 114A and an intermediate member 133; FIG. 5 is an explanatory diagram comparing features of an embodiment according to the present invention with a comparative example in opening and closing valve operations of an anchor 102, a plunger rod 114A and an intermediate member 133;

The construction of an embodiment of a fuel injection valve according to the present invention will be described below with reference to FIGS. 1, 2 and 3. FIG. FIG. 1 is a cross-sectional view parallel to a central axis 100a showing the structure of a fuel injection valve 100 according to one embodiment of the present invention. FIG. 2 is a partially enlarged view (sectional view) showing the vicinity of the anchor 102 in FIG. FIG. 3 is a partially enlarged view (sectional view) further enlarging the vicinity of the intermediate member 133 of FIG.

The fuel injection valve 100 of this embodiment urges the valve body 114B in the valve closing direction by a spring (first spring) 110, electromagnetically drives the mover 114 to open the fuel passage, and injects fuel. It is a type fuel injection valve. 1 and 2 show a state in which the electromagnetic drive section is de-energized, the valve is closed, and the mover 114 is stationary.

In the following description, the vertical direction is defined based on FIGS. 1 and 2. FIG. This vertical direction does not necessarily match the vertical direction when the fuel injection valve 100 is mounted. Further, in the fuel injection valve 100, the fuel supply port 118 side may be referred to as the proximal end side, and the fuel injection hole 10 side may be referred to as the distal end side. That is, the fuel supply port 118 is provided at the proximal end of the fuel injection valve 100 and the fuel injection hole 10 is provided at the distal end of the fuel injection valve 100 . In this embodiment, the center axis 100a of the fuel injection valve 100 is defined as shown in FIG. 100a. In the following description, the direction along the central axis 100a will be referred to as the axial direction.

The nozzle holder 101 includes a small-diameter tubular portion 101A and a large-diameter large-diameter tubular portion 101B. A guide member 115 and an orifice cup (fuel injection forming member) 116 having a fuel injection hole 10 are inserted into the tip portion of the small-diameter cylindrical portion 101A. The guide member 115 is provided inside the orifice cup 116 and fixed to the orifice cup 116 by press fitting or plastic coupling. The orifice cup 116 is welded and fixed to the distal end portion of the small-diameter cylindrical portion 101A along the outer peripheral portion of the distal end surface. The guide member 115 axially guides the outer periphery of a valve body 114B provided at the tip of a plunger rod (valve member) 114A that constitutes a movable element 114, which will be described later. A conical valve seat 39 is formed on the side of the orifice cup 116 facing the guide member 115 . A valve body 114B provided at the tip of the plunger 114A abuts against the valve seat 39 to introduce or block the flow of fuel to the fuel injection hole 10. As shown in FIG. A groove is formed in the outer periphery of the nozzle holder 101, and a sealing member represented by a chip seal 184 made of a resin material is fitted in the groove.

Here, the configuration of mover 114 will be described in detail with reference to FIG.

The end (base end) of the plunger rod 114A opposite to the end (distal end) where the valve element 114B is provided is stepped with an outer diameter larger than the diameter of the plunger rod 114A. A head 114C having a portion 129 is provided. The stepped portion (flange portion) 129 constitutes a flange portion protruding like a flange from the outer peripheral surface of the plunger rod 114A. A projecting portion 131 having a diameter smaller than that of the stepped portion 129 is provided from the upper end surface of the stepped portion 129 to the upper portion. That is, a head portion 114C composed of a stepped portion 129 and a projection portion 131 is provided at the proximal end portion of the plunger rod 114A. A cap 132 having a seating surface for the spring (first spring) 110 is provided at the upper end of the protrusion 131 . The cap 132 is press-fitted and fixed to the protrusion 131 .

The armature 114 has an anchor 102 with a central through hole 128 through which the plunger rod 114A passes. A zero spring (second spring) 112 is held between the anchor 102 and the nozzle holder 101 . One end of the zero spring 112 is supported by the main body of the fuel injection valve 100 (nozzle holder 101 in this embodiment), and the other end is in contact with the lower end surface 102B of the anchor 102. energized. This biasing force (set load) acts on the anchor 102 in a direction opposite to the biasing force (set load) of the first spring 110 . That is, the first spring 110 biases the plunger rod 114A in the valve closing direction, and the second spring 112 biases the anchor 102 from the opposite side of the fixed core 107 in the valve opening direction. One end of the first spring 110 is supported by the main body of the fuel injection valve 100 (the adjuster 54 in this embodiment), and the other end is supported by the cap 132 .

A concave portion 102C is formed in the upper end surface 102A of the anchor 102 toward the lower end surface 102B side, and an intermediate member 133 is provided inside the concave portion 102C. A concave portion 133A is formed on the lower surface side of the intermediate member 133, and the concave portion 133A has a diameter (inner diameter) and a depth that accommodate the stepped portion 129 of the head portion 114C. That is, the diameter (inner diameter) of recess 133A is greater than the diameter (outer diameter) of stepped portion 129, and the depth dimension of recess 133A is greater than the dimension between upper end surface 129A and lower end surface 129B of stepped portion 129. big. A through hole 133B through which the projection 131 of the head 114C penetrates is formed in the bottom of the recess 133A.

In this embodiment, the anchor 102 is axially displaceable relative to the plunger rod 114A. The stepped portion 129 of the plunger rod 114A engages with the anchor 102 to restrict relative displacement of the anchor 102 when the anchor 102 is displaced relative to the plunger rod 114A in the valve opening direction.

A spring (third spring) 134 is held between the intermediate member 133 and the cap 132, and an upper end surface 133C of the intermediate member 133 constitutes a spring seat against which one end of the third spring 134 abuts. The third spring 134 urges the anchor 102 in the valve closing direction from the fixed core 107 side via the intermediate member 133 .

A flange portion 132A projecting radially outward is formed on the upper end portion of the cap 132 positioned above the intermediate member 133, and the other end portion of the third spring 134 contacts a lower end surface 132B of the flange portion 132A. A seat is formed, and a spring seat is formed in which one end (lower end) of the first spring 110 abuts against the upper end surface 132I of the flange portion 132A. A tubular portion 132C is formed downward from the lower end surface of the collar portion 132A of the cap 132, and the projecting portion 131 is press-fitted and fixed to the inner circumference of the tubular portion 132C.

Since the cap 132 and the intermediate member 133 each form a spring seat for the third spring 134 , the diameter (inner diameter) of the through hole 133B of the intermediate member 133 is smaller than the diameter (outer diameter) of the flange 132A of the cap 132 . Therefore, the intermediate member 133 and the third spring 134 are assembled to the plunger rod 114A before the cap 132 and the protrusion 131 are press-fitted.

The cap 132 receives the biasing force of the first spring 110 from above and the biasing force (set load) of the third spring 134 from below. As will be described later, the biasing force of the first spring 110 is greater than the biasing force of the third spring 134, and as a result, the cap 132 is biased by the difference between the biasing force of the first spring 110 and the biasing force of the third spring 134. It is pressed against the protrusion 131 by force. Since no force is applied to the cap 132 in a direction to remove it from the projection 131, it is sufficient to press-fit and fix the cap 132 onto the projection 131, and welding is not necessary.

The intermediate member 133 will be explained again. The state shown in FIGS. 2 and 3 is a state in which the plunger rod 114A receives the biasing force of the first spring and no electromagnetic force acts on the anchor 102. FIG. In this state, the valve body 114B is in contact with the valve seat 39, the fuel injection valve 100 is closed, and the mover 114 is stationary and stable.

In this state, the intermediate member 133 receives the biasing force of the third spring 134, and the bottom surface 133A2 of the recess 133A contacts the upper end surface 129A of the stepped portion 129 of the plunger rod 114A. That is, the size (dimension) of the gap G3 between the bottom surface 133A2 of the recessed portion 133A and the upper end surface 129A of the stepped portion 129 is zero. The bottom surface 133A2 of the intermediate member 133 and the upper end surface 129A of the stepped portion 129 respectively constitute contact surfaces with which the intermediate member 133 and the stepped portion 129 of the plunger rod 114A come into contact.

On the other hand, the anchor 102 receives the biasing force of the zero spring (second spring) 112 and is biased toward the fixed core 107 side. Therefore, the bottom surface 102C2 of the recess 102C of the anchor 102 contacts the lower end surface of the intermediate member 133 (the opening edge of the recess 133A) 133D. Since the biasing force of the second spring 112 is weaker (smaller) than the biasing force of the third spring 134, the anchor 102 cannot push back the intermediate member 133 biased by the third spring 134, and the intermediate member 133 and the third spring 134 stop the upward movement (in the valve opening direction). The bottom surface 102C2 of the anchor 102 and the lower end surface 133D of the intermediate member 133 constitute contact surfaces with which the anchor 102 and the intermediate member 133 come into contact.

Since the depth dimension of the recessed portion 133A of the intermediate member 133 is larger than the dimension between the upper end surface 129A and the lower end surface 129B of the stepped portion 129, in the state shown in FIG. 129, and the gap G2 between the bottom surface 102C2 and the lower end surface 129B has a size (dimension) of D2. The gap G2 is smaller than the size (dimension) D1 of the gap G1 between the upper end surface (surface facing the fixed core 107) 102A of the anchor 102 and the lower end surface (surface facing the anchor 102) 107B of the fixed core 107. (D2<D1). As described here, the intermediate member 133 is a member that forms a gap G2 of size D2 between the bottom surface 102C2 of the anchor 102 and the lower end surface 129B of the stepped portion 129, and is called a gap forming member. It's okay.

The intermediate member (gap forming member) 133 is positioned on the stepped portion upper end surface (reference position) 129A of the plunger rod 114A, and the lower end surface 133D comes into contact with the anchor 102, so that the engagement portion of the plunger rod 114A ( A gap D2 is formed between the stepped portion lower end surface 129B and the engaging portion of the anchor 102 (recess bottom surface 102C2). The third spring 134 biases the intermediate member 133 in the valve closing direction so as to position it on the stepped portion upper end surface (reference position) 129A. The intermediate member 133 is positioned on the stepped portion upper end surface (reference position) 129A by the recess bottom surface 133A2 coming into contact with the stepped portion upper end surface (reference position) 129A.

Here, the urging forces of the three springs explained above will be explained again. Among the first spring 110, the second spring 112, and the third spring 134, the spring force (biasing force) of the first spring 110 is the largest, and the spring force (biasing force) of the third spring 134 is second largest. The spring force (biasing force) of the second spring 112 is the smallest.

In the mover 114 of this embodiment, the diameter of the through-hole 128 formed in the anchor 102 is smaller than the diameter of the stepped portion 129 of the head 114C (see FIG. 1), so that the valve is changed from the closed state to the open state. During the valve opening operation that transitions or during the valve closing operation that transitions from the valve open state to the valve closed state, the lower end surface 129B of the stepped portion 129 of the plunger rod 114A engages with the bottom surface 102C2 of the anchor 102, and the anchor 102 It will move in cooperation with the plunger rod 114A. However, when the force that moves the plunger rod 114A upward (valve opening direction) or the force that moves the anchor 102 downward (valve closing direction) acts independently, the plunger rod 114A and the anchor 102 move in different directions. be able to. The operation of mover 114 will be described later in detail.

In this embodiment, the anchor 102 is guided in movement in the vertical direction (in the opening/closing valve direction) by the outer peripheral surface of the anchor 102 coming into contact with the inner peripheral surface of the large-diameter cylindrical portion 101B of the nozzle holder 101 . Furthermore, the plunger rod 114A is guided in movement in the vertical direction (opening/closing valve direction) by contacting the inner peripheral surface of the through hole 128 of the anchor 102 with the outer peripheral surface 114A1 thereof. That is, the inner peripheral surface of the large-diameter tubular portion 101B of the nozzle holder 101 functions as a guide when the anchor 102 moves in the axial direction, and the inner peripheral surface of the through hole 128 of the anchor 102 moves the plunger rod 114A in the axial direction. It works as a guide when moving. The tip of the plunger rod 114A is guided by the guide hole of the guide member 115, and is guided by the guide member 115, the large-diameter cylindrical portion 101B of the nozzle holder 101, and the through hole 128 of the anchor 102 so as to reciprocate straight. ing.

The lower end surface 102B of the anchor 102 faces the stepped surface between the large-diameter tubular portion 101B and the small-diameter tubular portion 101A of the nozzle holder 101, but the second spring 112 is interposed to prevent the two from coming into contact with each other. no.

A lower end surface (collision surface) 107B of the core 107, an upper end surface (collision surface) 102A of the anchor 102, upper and lower end surfaces (contact surfaces) 133C and 133D of the intermediate member 133, and an upper and lower end surface (contact surface) 129A of the stepped portion 129. , 129B may be appropriately plated to improve durability. Even when relatively soft soft magnetic stainless steel is used for the anchor 102, durability and reliability can be ensured by using hard chrome plating or electroless nickel plating.

Note that the impact force on the contact surface between the anchor 102 and the intermediate member 133 and the contact surface between the intermediate member 133 and the stepped portion 129 is far greater than the impact force on the contact surface between the anchor 102 and the fixed core 107. The contact surface between the anchor 102 and the intermediate member 133 and the contact surface between the intermediate member 133 and the stepped portion 129 need plating less than the need for plating on the contact surface between the anchor 102 and the fixed core 107. sex is much smaller.

In this embodiment, it is assumed that the top surface 102A of the anchor 102 and the bottom surface 107B of the fixed core 107 are in contact with each other, but either the top surface 102A of the anchor 102 or the bottom surface 107B of the fixed core 107 is used. On the other hand, there is also a case in which protrusions are provided on both the upper end surface 102A of the anchor 102 and the lower end surface 107B of the fixed core 107, and the protrusions and the end surfaces or the protrusions abut against each other. In this case, the gap G1 described above is the gap between the contact portion on the anchor 102 side and the contact portion on the fixed core 107 side.

Returning to FIG. 1 again, description will be made. A fixed core 107 is press-fitted into the inner peripheral portion of the large-diameter tubular portion 101B of the nozzle holder (housing member) 101 and welded at the press-fit contact position. The fixed core 107 is a component that applies a magnetic attraction force to the anchor 102 to attract the anchor 102 in the valve opening direction. A gap formed between the inside of the large-diameter cylindrical portion 101B of the nozzle holder 101 and the outside air is sealed by the welding connection of the fixed core 107 . A through hole 107A having a diameter slightly larger than that of the intermediate member 133 is provided in the center of the fixed core 107 as a fuel passage. A head portion 131 and a cap 132 of the plunger rod 114A are inserted through the inner periphery of the lower end portion of the through hole 107A in a non-contact state.

The lower end of the first spring 110 for setting the initial load is in contact with the spring receiving surface formed on the upper end surface of the cap 132 provided on the head 131 of the plunger rod 114A, and the other end of the first spring 110 is fixed. The first spring 110 is fixed between the cap 132 and the adjuster 54 by being received by the adjuster 54 press-fitted into the through hole 107</b>A of the core 107 . By adjusting the fixing position of the adjuster 54, the initial load with which the first spring 110 presses the plunger rod 114A against the valve seat 39 can be adjusted.

The stroke of the mover 114 is adjusted by setting the anchor 102 inside the large-diameter cylindrical portion 101B of the nozzle holder 101, and then rotating the electromagnetic coil 105 wound around the bobbin 104 around the outer circumference of the large-diameter cylindrical portion 101B of the nozzle holder 101 and the housing. After mounting 103 , the plunger rod 114 A assembled with the cap 132 , the intermediate member 133 and the third spring 134 is inserted through the anchor 102 through the through hole 107 A of the fixed core 107 . In this state, the plunger rod 114A is pressed to the valve closing position by a jig, and the press-fit position of the orifice cup 116 is determined while detecting the stroke of the plunger rod 114 when the coil 105 is energized. Adjust the stroke to any position.

With the initial load of the spring 110 adjusted, the lower end surface 107B of the fixed core 107 faces the upper end surface 102A of the anchor 102 of the mover 114 across a magnetic attraction gap G1 of approximately 70 to 150 microns. is configured to It should be noted that in the drawing, the size ratio is disregarded and the display is enlarged.

Next, operation of the mover 114 will be described with reference to FIGS. 2 to 8 (8A and 8B).

FIG. 2 shows the state before the anchor 102 starts moving in the valve-opening direction (the initial position when the valve is still closed). Plunger rod 114A and anchor 102 are separated by a first gap (first sliding part) 141 (gap gap Ga in FIG. 3), and plunger rod stepped part 129 and intermediate member 133 are separated by a second gap ( It has a slidable structure via a second sliding portion 142 (gap portion Gb in FIG. 3). Between the anchor 102 and the intermediate member 133, there is also a third gap (third sliding part) 143 (gap portion Gc in FIG. 3) consisting of surfaces parallel to the movement direction and in close contact with each other. The first minute gap of the first gap, the second minute gap of the second gap, and the third minute gap of the third gap are each independently connected to the closed space 144 .

A pressure chamber (closed space) 144 surrounded by the plunger rod stepped portion 129, the anchor 102 and the intermediate member 133 is filled with fuel. Expand, shrink. At this time, fuel flows into and out of the pressure chamber 144 through the first gap 141 , the second gap 142 and the third gap 143 . In addition, through at least one of the first minute gap of the first gap portion 141, the second minute gap of the second gap portion 142, and the third minute gap of the third gap portion 143, the fuel is introduced between the closed space 144 and the outside. as long as it is possible to distribute

A connector 43A formed at the tip of the conductor 109 is connected to a plug for supplying power from a high-voltage power supply or a battery power supply, and energization/non-energization is controlled by a controller (not shown). While the coil 105 is energized, a magnetic attraction force is generated between the anchor 102 of the mover 114 and the fixed core 107 in the magnetic attraction gap G1, and the anchor 102 is attracted by a force exceeding the biasing force of the third spring 134. to start moving upwards.

In this state, there is a gap G1=D1 between the impact surface (upper end surface 102A) on the anchor 102 side and the impact surface (lower end surface 107B) on the fixed core 107 side, and the gap G1=D1 exists below the stepped portion 129 of the plunger rod 114A. A gap G2=D2 exists between the end surface 129B and the bottom surface 102C2 of the recess of the anchor 102. The recess bottom surface 133A2 of the intermediate member 133 and the upper end surface 129A of the stepped portion 129 are in contact, and the lower end surface 133D of the intermediate member 133 and the recess bottom surface 102C2 of the anchor 102 are in contact. The plunger rod 114A is biased in the valve closing direction by the biasing force of the first spring 110, and the valve body 114B is in contact with the valve seat 39. As shown in FIG.

In the state shown in FIG. 2, the anchor 102 is urged downward in the figure by the third spring 134 via the intermediate member 133 . Since the current flowing through the coil 105 gradually increases with time after energization, the biasing force of the third spring 134 is greater than the magnetic attraction force immediately after the start of energization of the coil 105, and the anchor 102 does not move.

When the magnetic attraction force exceeds the biasing force of the third spring 134, the anchor 102 begins to move.

Using FIG. 8A, the operation of the mover 114 of this embodiment will be compared with that of the comparative example. FIG. 8A is an explanatory diagram comparing features of an embodiment according to the present invention with a comparative example in opening and closing valve operations of the anchor 102, plunger rod 114A and intermediate member 133. FIG. In FIG. 8A, (b) shows an example of the present invention, and (a) shows a comparative example. A comparative example configuration corresponding to plunger rod 114A, stepped portion 129, anchor 102 and intermediate member 133 of the present example is shown as plunger rod 114A', stepped portion 129', anchor 102' and intermediate member 133'. The state in FIG. 2 corresponds to the state (1) in FIG. 8A.

FIG. 4 is a cross-sectional view similar to FIG. 2, showing the state of the mover 114 during the valve opening operation. FIG. 4 shows a state in which a certain period of time has passed since the start of energization of the coil 105, and the bottom surface 102C2 of the recessed portion of the anchor 102 has reached the lower end surface 129B of the stepped portion 129 of the plunger rod.

In the state of FIG. 4, the gap G2=0. The gap G3 is G3=D2 because the intermediate member 133 is pushed up by the distance D2. Also, the gap G1 is reduced by the distance D2 and becomes D3 (=D1-D2). The pressure chamber 144 shrinks as the state shifts from FIG. 3 to FIG. During this process, the fuel in the pressure chamber 144 leaks out of the pressure chamber 144 through the first gap 141 , the second gap 142 and the third gap 143 . This outflow velocity is proportional to the moving velocity of the anchor 102. In the first to third gaps 141 to 143, a pressure loss proportional to the square of the outflow velocity occurs, and the pressure in the pressure chamber 144 is However, since the compressibility of the fuel is very small, there is no pressure difference between the outside and the inside of the pressure chamber 144 when the volume of the pressure chamber 144 does not change. The state of FIG. 4 corresponds to the state shown in (2) of FIG. 8A.

FIG. 5 is a cross-sectional view similar to FIG. 2 showing anchor 102 impacting fixed core 107. FIG. FIG. 5 shows the positional relationship of the plunger rod stepped portion 129 (plunger rod 114A), the anchor 102 and the intermediate member 133 in a state in which time has passed since the state of FIG. It shows the positional relationship of each member at the time of arrival. At this stage, the gap G1 becomes 0, and at the same time the upward moving speed of the anchor 102 instantly becomes zero. At this time, G2 and G3 maintain the same state as in FIG. 5, the plunger rod stepped portion 129 and the intermediate member 133 continue to rise due to inertia against the anchor 102 that has stopped moving upward, jumping up from the upper end surface 102A of the anchor 102. It will be in an overshoot state.

The initial state of the overshoot state corresponds to the state shown in (3) of FIG. 8A. That is, the state shown in (3) of FIG. 8A is an intermediate state between the state shown in FIG. 5 and the state shown in FIG. Only plunger rod 114A is separated from anchor 102 and overshoots. In this embodiment, a negative pressure area is formed in the pressure chamber 144 from this stage, and the effect of suppressing the overshoot of the plunger rod 114A and the intermediate member 133 is obtained from the point of time when the negative pressure area is formed. In particular, the intermediate member 133 having a small mass has a small inertial force contributing to separation from the anchor 102 and jumping, and is less likely to jump from the anchor 102 due to the influence of the negative pressure region.

On the other hand, in the comparative example, a large gap is formed between the plunger rod stepped portion 129', the anchor 102', and the intermediate member 133', and a pressure chamber cannot be configured, and the space 144' is set to a negative pressure. unable to maintain. In the comparative example at this stage, the effect of suppressing the overshoot of the plunger rod 114A' is not obtained.

FIG. 6 is a cross-sectional view similar to FIG. 2 showing an overshoot condition in which plunger rod 114A separates from anchor 102 and operates alone. FIG. 6 shows the positional relationship of the plunger rod stepped portion 129, the anchor 102 and the intermediate member 133 in the overshoot state in which more time has passed since the state of FIG. continues to rise and the gap G2 increases (G2=D4 in FIG. 6). Here, since the pressure chamber 144 continues to expand in volume, it has a negative pressure. flows in. This inflow velocity is proportional to the moving velocity of the plunger rod stepped portion 129 and the intermediate member 133, and a pressure loss proportional to the square of the inflow velocity occurs in the first to third gaps 141 to 143. , the pressure in the pressure chamber 144 becomes a negative pressure. This negative pressure acts on the plunger rod stepped portion 129 and the intermediate member 133 as a force in the direction of preventing them from being detached from the anchor 102, thus contributing to the reduction of overshoot.

The overshoot state shown in FIG. 6 corresponds to the state shown in (4) of FIG. 8A, in which both the plunger rod 114A and the intermediate member 133 are separated from the anchor 102 and are in the overshoot state. The overshoot state shown in (4) of FIGS. 6 and 8A is a state in which the plunger rod 114A and the intermediate member 133 are rising, and is in a rising state in the overshoot state. In this embodiment, a negative pressure region is formed in the pressure chamber 144 even at this stage, and an effect of suppressing overshoot of the plunger rod 114A and the intermediate member 133 is obtained.

On the other hand, in the comparative example, the contact between the plunger rod stepped portion 129' and the intermediate member 133' causes the space 144' to become a pressure chamber, and a negative pressure region is formed in the pressure chamber 144'. In the comparative example, from this stage, the effect of suppressing overshoot of the plunger rod 114A' and the intermediate member 133' is obtained.

Since the plunger rod 114A is biased in the valve closing direction by the biasing force of the first spring 110, the plunger rod stepped portion 129 and the intermediate member 133 move downward after rising by a certain distance. After the descent starts, the volume of the pressure chamber 144 starts to decrease, and the fuel flows out of the pressure chamber 144 through the first gap 141, the second gap 142, and the third gap 143. This outflow velocity is proportional to the moving velocity of the plunger rod stepped portion 129 and the intermediate member 133, and a pressure loss proportional to the square of the outflow velocity occurs in the first to third gaps 141 to 143. , the pressure in the pressure chamber rises. This increased pressure acts on the intermediate member 133 and has the effect of pushing back the intermediate member 133 in a situation where the biasing force of the third spring 134 is greater, reducing the speed at which the intermediate member 133 collides with the anchor 102 .

This state corresponds to the state shown in (5) of FIG. 8A, a positive pressure region is formed in the pressure chamber 144, and the speed of the plunger rod 114A and the intermediate member 133 during overshoot descent is suppressed.

After the overshoot of plunger rod 114A and intermediate member 133 converges, the state of FIG. 5 is maintained while power is being supplied to coil 105. FIG. After the power supply to the coil 105 is stopped, the plunger rod 114A, the intermediate member 133 and the anchor 102 start to descend and once return to the initial state of FIG. abruptly stop. This state corresponds to the state shown in (6) in FIG. 8A ((6) in FIG. 8B). In this case, the anchor 102 cannot maintain the state shown in FIG. 2 due to the inertial force, and sinks from the state shown in FIG. 2, resulting in an undershoot state.

FIG. 7 is a cross-sectional view similar to FIG. 2 showing an undershoot condition in which anchor 102 separates from stepped portion 129 of plunger rod 114A and operates alone. FIG. 7 shows the positional relationship among the plunger rod stepped portion 129, the anchor 102, and the intermediate member 133 in the undershoot state, where the anchor 102 continues to descend and the gap G2 increases (G2=D6 in FIG. 7). . This state corresponds to the state shown in (9) in FIG. 8B, and the state shown in (6) in FIG. 8B passes through the states shown in (7) and (8) to reach the state shown in (9).

In this embodiment, a negative pressure region is formed in the pressure chamber 144 from the state shown in (7) of FIG. 8B. That is, from the time the anchor 102 separates from the plunger rod stepped portion 129, a negative pressure region is formed in the pressure chamber 144, and an effect of suppressing the undershoot of the anchor 102 is obtained.

On the other hand, in the comparative example, a large gap is formed between the plunger rod stepped portion 129', the anchor 102', and the intermediate member 133', and a pressure chamber cannot be configured, and the space 144' is set to a negative pressure. unable to maintain. In the comparative example at this stage, the effect of suppressing the undershoot of the anchor 102' is not obtained.

In the states shown in (9) and (10) of FIG. 8B, the pressure chamber 144 of the present embodiment continues to expand in volume, so that the pressure is negative. Fuel flows into the pressure chamber 144 from outside through the third gap 143 . This inflow velocity is proportional to the moving velocity of the anchor 102. In the first to third gaps 141 to 143, a pressure loss proportional to the square of the inflow velocity occurs, and the pressure in the pressure chamber 144 is negative pressure. This negative pressure acts on the anchor 102 as a force in the direction of preventing it from being detached from the plunger rod stepped portion 129 and the intermediate member 133, thereby contributing to the reduction of undershoot.

On the other hand, in the comparative example, the contact between the plunger rod stepped portion 129' and the intermediate member 133' causes the space 144' to become a pressure chamber, and a negative pressure region is formed in the pressure chamber 144'. In the comparative example, the effect of suppressing the undershoot of the plunger rod 114A' and the intermediate member 133' is obtained from this stage. However, when the state shown in (10) of FIG. 8B is reached, the anchor 102' is separated from the intermediate member 133', the pressure chamber 144' is opened to the outside, the negative pressure area disappears, and the effect of suppressing undershoot is obtained. will not be

In this embodiment, the anchor 102 returns to the initial position shown in FIG. 2 after the undershoot is converged (undershoot climb), and the pressure in the pressure chamber 144 also rises at this time. This pressure increase acts on anchor 102 to counteract the biasing force of second spring 112 . As a result, the speed at which the anchor 102 rising by the biasing force of the second spring 112 collides with the lower end surface 133D of the intermediate member 133 is reduced. That is, as shown in (11) of FIG. 8B, a positive pressure region is formed in the pressure chamber 144, and the rising speed of the anchor 102 is suppressed.

On the other hand, in the comparative example, since the anchor 102' is separated from the intermediate member 133' in most of the range of the undershoot of the anchor 102', a positive pressure region is formed in the pressure chamber 144' at the anchor 102'. is just before returning to its initial position. Therefore, in the comparative example, it is difficult to obtain the effect of reducing the speed when the anchor 102' collides with the intermediate member 133'.

In this embodiment, due to the effects described above, the overshoot and undershoot of the plunger rod 114A, the anchor 102 and the intermediate member 133 can be reduced, and the characteristics of the valve are improved. Furthermore, since the collision speed between the intermediate member 133 and the anchor 102 can be reduced, there is an effect of suppressing wear of the intermediate member 133 .

In this embodiment, as shown in FIG. 3, in order to configure the pressure chamber 144, a ring-shaped projection (protrusion) 102E is provided in the recess 102C of the anchor 102. As shown in FIG. The protrusion 102E is formed to protrude radially inward from a side surface (inner peripheral surface) 102C1 of the recess 102C and to protrude upward (toward the opening of the recess 102C) from a bottom surface 102C2 of the recess 102C. The convex portion 102E has a side surface (inner peripheral surface) 102E1 and an upper end surface 102E2. A side surface (inner peripheral surface) 102E1 faces an outer peripheral surface 133E of the intermediate member 133 and forms a third gap 143. As shown in FIG.

The gap Ga of the first gap portion 141 is set to a minute gap to guide the plunger rod 114A with the anchor 102, and is set to a minute gap sufficient to form the pressure chamber 144. As shown in FIG. The gap Gb of the second gap 142 and the gap Gc of the third gap 143 are the same as or smaller than the gap Ga of the first gap 141 in order to form the pressure chamber 144. preferable.

Furthermore, the height dimension of the protrusion (protrusion) 102E is determined when the plunger rod 114A and the intermediate member 133 overshoot the anchor 102 and when the anchor 102 undershoots the plunger rod 114A and the intermediate member 133. In this case, the dimension is set so that the outer peripheral surface 133E of the intermediate member 133 and the side surface 102E1 of the convex portion 102E face each other. The height dimension of the projection (protrusion) 102E is the distance in the axial direction between the upper end surface 102E2 of the projection 102E and the bottom surface 102C2 of the recess 102C.

In addition, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments are detailed descriptions for easy understanding of the present invention, and are not necessarily limited to those having all the configurations. Moreover, it is possible to add, delete, or replace a part of the configuration of the embodiment with another configuration.

The fuel injection valve 100 of this embodiment has the following configuration.

(1) A plunger rod 114A having a valve body 114B at its tip, and an anchor 102 provided to be relatively displaceable in the axial direction with respect to the plunger rod 114A,
The plunger rod 114A has a stepped portion 129 that engages with the anchor 102 to restrict the relative displacement of the anchor 102 when the anchor 102 is displaced relative to the plunger rod 114A in the valve opening direction,
When the valve is closed, the plunger rod 114A and the anchor 102 are provided with an axial gap G2 by the intermediate member 133 between the stepped portion 129 and the engaging portion (upper end surface 102A) of the anchor 102 that engages with the stepped portion 129. is formed in the fuel injection valve 100,
A first sliding portion 141 in which the plunger rod 114A and the anchor 102 slide in the axial direction, a second sliding portion 142 in which the stepped portion 129 and the intermediate member 133 slide in the axial direction, and the anchor 102 and the intermediate and a third sliding portion 143 on which the member 133 slides in the axial direction,
The first minute gap formed in the first sliding portion 141, the second minute gap formed in the second sliding portion 142, and the third minute gap formed in the third sliding portion 143 are formed by the plunger rod 114A, It is connected to closed space 144 surrounded by anchor 102 and intermediate member 133 .

(2) The first minute gap, the second minute gap, and the third minute gap are each independently connected to the closed space 144 .

(3) At least one of the first minute gap, the second minute gap, and the third minute gap allows fuel to flow between the closed space and the outside.

(4) the anchor 102 has a recess 102C that accommodates the stepped portion 129 and the intermediate member 133;
The concave portion 102C has a convex portion 102E having an inner peripheral surface 102E1 facing the outer peripheral surface 133E of the intermediate member 133,
A third minute gap is formed between the outer peripheral surface 133E of the intermediate member 133 and the inner peripheral surface 102E1 of the recess 102C.

(5) The projection 102E protrudes radially inward from the inner peripheral surface 102C1 of the recess 102C, protrudes from the bottom surface 102C2 of the recess 102C toward the opening of the recess 102C, and is formed in an annular shape.

(6) The first sliding portion 141 constitutes a guide portion that guides the movement of the plunger rod 114A in the axial direction,
The interval dimension Gb of the second micro-gap and the interval dimension Gc of the third micro-gap are equal to or less than the interval dimension Ga of the first micro-gap.

DESCRIPTION OF SYMBOLS 102...Anchor 102C...Recessed part of anchor 102 102E...Convex part 102E1...Internal peripheral surface of convex part 102E 114A...Plunger rod 114B...Valve body 129...Stepped part of plunger rod 114A 133...Intermediate member , 133E... the outer peripheral surface of the intermediate member 133, 141... the first sliding portion (the first clearance), 142... the second sliding portion (the second clearance), 143... the third sliding portion (the third clearance) ), 144... Closed space.

Claims (5)

A plunger rod having a valve body provided at its tip, an anchor provided to be relatively displaceable in the axial direction with respect to the plunger rod, and an intermediate member interposed between the plunger rod and the anchor ,
The plunger rod has a stepped portion that engages with the anchor to restrict the relative displacement of the anchor when the anchor is displaced relative to the plunger rod in the valve opening direction,
When the valve is closed, the plunger rod , the anchor, and the intermediate member engage the stepped portion and the anchor that engages the stepped portion by abutting the anchor and the intermediate member in the axial direction. In a fuel injection valve in which an axial gap is formed between the
a first sliding portion in which the plunger rod and the anchor slide axially; a second sliding portion in which the stepped portion and the intermediate member slide axially; and the anchor and the intermediate member and a third sliding portion that slides in the axial direction,
A first minute gap formed in the first sliding portion and a second minute gap formed in the second sliding portion are connected to a closed space surrounded by the plunger rod, the anchor and the intermediate member,
The third minute gap formed in the third sliding portion is formed by releasing the contact between the anchor and the intermediate member in the axial direction during the valve opening operation and the valve closing operation. , connected to a closed space surrounded by the anchor and the intermediate member ,
The first sliding portion constitutes a guide portion that guides the movement of the plunger rod in the axial direction,
The fuel injection valve , wherein the interval dimension of the second minute gap and the interval dimension of the third minute gap are equal to or less than the interval dimension of the first minute gap . In the fuel injection valve according to claim 1,
The fuel injection valve, wherein the first minute gap, the second minute gap, and the third minute gap are each independently connected to the closed space. In the fuel injection valve according to claim 2,
The fuel injection valve, wherein at least one of the first minute gap, the second minute gap and the third minute gap allows fuel to flow between the closed space and the outside. In the fuel injection valve according to claim 3,
the anchor includes a recess that accommodates the stepped portion and the intermediate member;
The concave portion includes a convex portion having an inner peripheral surface facing the outer peripheral surface of the intermediate member,
The fuel injection valve, wherein the third minute gap is formed between the outer peripheral surface of the intermediate member and the inner peripheral surface of the recess. In the fuel injection valve according to claim 4,
The fuel injection valve, wherein the projection protrudes radially inward from an inner peripheral surface of the recess, protrudes from a bottom surface of the recess toward an opening side of the recess, and forms an annular shape. .

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