WO2023276244A1

WO2023276244A1 - Fuel injection device

Info

Publication number: WO2023276244A1
Application number: PCT/JP2022/005961
Authority: WO
Inventors: 寛向井; 泰介杉井; 威生三宅; 明靖宮本; 真士菅谷; 直樹米谷
Original assignee: 日立Astemo株式会社
Priority date: 2021-07-01
Filing date: 2022-02-15
Publication date: 2023-01-05
Also published as: JP2023006921A

Abstract

This fuel injection device comprises a nozzle holder provided with an injection hole formation member, a fixed core disposed in the nozzle holder, an anchor, and a valve member. The anchor faces the fixed core and is disposed in an accommodating recess provided in the nozzle holder. An insertion hole into which the valve member is inserted is formed in the anchor. Gaps through which a fluid can pass are formed between the anchor and the nozzle holder and between the insertion hole and the valve member.

Description

fuel injector

The present invention relates to a fuel injection device.

Conventionally, as an internal combustion engine, an in-cylinder injection type internal combustion engine in which a fuel injection device directly injects fuel into the cylinder has been used. Further, in recent years, from the viewpoint of reducing exhaust emissions, it is required to be able to inject fuel in multiple stages at high pressure and to suppress variations in the amount of fuel injected during low pulses.

For example, Patent Document 1 describes a technology related to a conventional fuel injection device.

Patent Literature 1 describes a technique that includes a valve member, an anchor that is relatively displaceable with respect to the valve member, and a fixed core having a through hole. Both the anchor and the valve member are provided with an engaging portion that engages when the anchor is displaced in the valve opening direction with respect to the valve member to restrict the displacement of the anchor in the valve opening direction. Further, the gap forming member includes a gap forming member that forms a gap between the engaging portion on the valve member side and the engaging portion on the anchor side, and a biasing spring that biases the gap forming member in the valve closing direction. , the outer diameter of the urging spring, and the maximum outer diameter of the valve member are smaller than the inner diameter of the through hole.

WO2016/042896

In addition, in the technique described in Patent Document 1, since the anchor is slidably supported by the valve body, the gap formed between the stepped portion of the valve body and the gap forming member indicating the spacer is In the valve closed state, it was a closed space. When the closed state changes to the open state, the pressure in this gap fluctuates greatly, affecting the valve opening operation.

Furthermore, the size of the gap formed between the stepped part and the spacer was different for each individual fuel injection device due to the dimensional error of each individual fuel injection device. Due to the difference in the size of the gap, the size of the pressure fluctuation during the opening operation also varies from individual to individual. Then, an individual with a low pressure in the gap opens the valve faster, and an individual with a higher pressure opens the valve slower. As a result, in the technique described in Patent Document 1, the fuel injection amount varies.

An object of the present invention is to provide a fuel injection device capable of suppressing variations in fuel injection amount in consideration of the above problems.

In order to solve the above problems and achieve the object of the present invention, a fuel injection device includes a nozzle holder provided with an injection hole forming member, a fixed core arranged in the nozzle holder, an anchor, and a valve member. I have. The anchor faces the fixed core and is arranged in a housing recess provided in the nozzle holder. The valve member has a valve body that opens and closes the injection holes provided in the injection hole forming member.
The anchor has an insertion hole through which the valve member is inserted. Gaps through which fluid can pass are formed between the anchor and the nozzle holder and between the insertion hole and the valve member.

According to the fuel injection device configured as described above, it is possible to suppress variations in the amount of fuel injected.

1 is a sectional view showing a fuel injection device according to a first embodiment; FIG. FIG. 2 is an enlarged cross-sectional view showing the surroundings of spacers and anchors in the fuel injection device according to the first embodiment; 3A is a sectional view taken along the line A-A' shown in FIG. 2, and FIG. 3B is a sectional view showing the anchor of the fuel injection device according to the first embodiment. FIG. 4A shows an example in which the eccentricity is increased, and FIG. 4B shows an example in which the eccentricity is decreased. FIG. 4 is an enlarged cross-sectional view showing the periphery of the spacer and the anchor when the valve opening operation is completed in the fuel injection device according to the first embodiment; FIG. 8 is a cross-sectional view showing an anchor and a nozzle holder in the fuel injection device according to the second embodiment; FIG. 11 is a sectional view showing an anchor and a nozzle holder in a fuel injection device according to a third embodiment;

Embodiments of the fuel injection device will be described below with reference to FIGS. 1 to 7. FIG. In addition, the same code|symbol is attached|subjected to the member which is common in each figure.

1. First embodiment example 1-1. Configuration of Fuel Injection Apparatus First, the configuration of a fuel injection apparatus according to a first embodiment (hereinafter referred to as "this example") will be described with reference to FIG.
FIG. 1 is a cross-sectional view showing a fuel injection device.

The fuel injection device shown in FIG. 1 is used as an internal combustion engine in a four-cycle engine that repeats four strokes of an intake stroke, a compression stroke, a combustion (expansion) stroke, and an exhaust stroke. Further, the fuel injection device is applied to an in-cylinder injection type internal combustion engine that injects fuel into each cylinder.

As shown in FIG. 1, the fuel injection device 100 includes a fixed core (magnetic core) 101, a nozzle holder 102, an injection hole forming member 103, a valve member 104, an electromagnetic coil 108, a housing 109, an anchor ( movable core) 110 and a connecting portion 135 . The fuel injection device 100 also includes a first spring 118 , a second spring 124 and a third spring 126 .

[Nozzle holder]
The nozzle holder 102 is formed in a cylindrical shape. An injection hole forming member 103 is inserted or press-fitted to the tip of the nozzle holder 102 along the central axis 100a in the axial direction Da (hereinafter simply referred to as "axial direction Da"). An injection hole 112 for injecting fuel is formed in the injection hole forming member 103 .

Further, the injection hole forming member 103 is formed with a valve seat 103a on which a tip portion of a valve body 117 of the valve member 104 to be described later contacts and separates. By doing so, the fuel is sealed. Further, the valve element 117 seals the fuel by coming into contact with the valve seat 103a, and permits passage of the fuel by separating from the valve seat 103a.

A guide member 105 is fixed to the tip of the nozzle holder 102 by press fitting or plastic coupling. The guide member 105 supports the outer peripheral surface of the valve body 117 in the valve member 104 and guides movement of the valve body 117 .

A large-diameter portion 102a having an outer diameter larger than that of the tip portion is formed at the rear end portion, which is the other end portion of the nozzle holder 102 in the axial direction Da. A housing recess 102b is formed in the large diameter portion 102a. This accommodation recess 102b communicates with the tip portion through a communication hole 102c formed along the axial direction Da of the nozzle holder 102 .

The accommodation recess 102b is a bottomed recess that is open at the rear end side of the large diameter portion 102a and is recessed toward the front end side in the axial direction Da. An anchor 110, which will be described later, and a part of the fixed core 101 are arranged in the accommodation recess 102b. One end of the second spring 124 is accommodated in the central portion of the bottom of the accommodation recess 102b. The housing recess 102b slidably supports an anchor 110, which will be described later, on its inner wall surface along the axial direction Da.

In addition, a groove 115 is formed in the downstream outer peripheral portion (outside in the radial direction) of the nozzle holder 102 , and a sealing member 116 typified by a chip seal made of resin material is fitted in the groove 115 .

[Valve member]
A valve member 104 is arranged inside the nozzle holder 102 so as to be movable along the axial direction Da. Valve member 104 includes plunger rod 113 , spacer 125 , third spring 126 and rod head 127 . A detailed configuration of the valve member 104 will be described later.

[anchor]
Next, the anchor 110 will be explained. The anchor 110 is arranged in the housing recess 102b of the nozzle holder 102 between the spacer 125 of the valve member 104 and the bottom of the housing recess 102b. A small gap is formed between the outer peripheral surface of the anchor 110 and the inner peripheral surface of the housing recess 102b. Therefore, the anchor 110 is arranged movably along the axial direction Da within the accommodation recess 102b.

The anchor 110 is formed in a cylindrical shape. The anchor 110 is formed with an insertion hole 110c (see FIG. 2) and an eccentric through hole 110d. The insertion hole 110c and the eccentric through hole 110d are guide holes that penetrate from the front end portion to the rear end portion of the anchor 110 in the axial direction Da. A plunger rod 113 of the valve member 104 is inserted through the insertion hole 110c.

The eccentric through-hole 110 d is formed at a position eccentric from the central axis of the anchor 110 .
The eccentric through-hole 110 d communicates with the flow path formed by the through-hole 101 a of the fixed core 101 . The eccentric through-hole 110d forms a flow path through which fuel passes.

The rear end portion of the second spring 124 is in contact with the end face of the anchor 110 on the tip side in the axial direction Da. Therefore, the second spring 124 is interposed between the anchor 110 and the accommodation recess 102b of the nozzle holder 102. As shown in FIG. A fixed core 101 is arranged on the rear end side of the anchor 110 in the axial direction Da.

A detailed configuration of the anchor 110 will be described later.

[Fixed core]
The fixed core 101 is a member that attracts the anchor 110 by magnetic attraction. The fixed core 101 is formed in a substantially cylindrical shape having unevenness on the outer peripheral surface. The distal end portion of the fixed core 101 in the axial direction Da is press-fitted inside the large-diameter portion 102a of the nozzle holder 102, that is, inside the housing recess 102b. Then, the nozzle holder 102 and the fixed core 101 are joined by welding. Thereby, the gap between the nozzle holder 102 and the fixed core 101 is sealed, and the space inside the nozzle holder 102 is sealed.

In addition, the distal end portion 101b of the fixed core 101 faces the end surface of the anchor 110 arranged in the housing recess 102b on the other end side in the axial direction Da. The rear end side of the fixed core 101 in the axial direction Da protrudes from the housing recess 102b of the nozzle holder 102 toward the rear end in the axial direction Da.

A through hole 101 a is formed in the fixed core 101 . The through hole 101a is formed coaxially with the center axis 100a. The through hole 101a forms a flow path through which fuel passes. A fuel supply port 111 communicating with the through hole 101a is formed at the rear end portion of the fixed core 101 in the axial direction Da. Fuel is introduced from the fuel supply port 111 toward the through hole 101a.

Further, a first spring 118 and an adjusting member 119 are arranged on the tip end side of the through hole 101a in the axial direction Da. The first spring 118 is arranged closer to the distal end of the through hole 101 a than the adjustment member 119 is. The adjusting member 119 is press-fitted into the through hole 101 a and fixed inside the fixed core 101 . A rod head 127, a third spring 126 and a spacer 125 of the valve member 104 are inserted into the through hole 101a.
The through hole 101a slidably supports a rod head 127 of the valve member 104, which will be described later, along the axial direction Da.

The first spring 118 is interposed between the adjustment member 119 and the rod head 127 of the valve member 104 . The first spring 118 urges the valve member 104 toward the tip of the nozzle holder 102 in the axial direction Da.

Further, by adjusting the fixing position of the adjusting member 119 with respect to the fixed core 101, the biasing force of the first spring 118 on the valve member 104 can be adjusted. Thereby, the initial load that the valve body 117, which is the tip of the plunger rod 113 in the valve member 104, presses against the valve seat 103a provided in the injection hole forming member 103 of the nozzle holder 102 can be adjusted.

Here, the biasing force of the first spring 118 biasing the valve member 104 toward the tip of the nozzle holder 102 is greater than the biasing force of the second spring 124 biasing the anchor 110 toward the fixed core 101. is set.

A fuel filter (not shown) is provided on the upstream inner peripheral portion (inside in the radial direction) of the fixed core 101 . A seal member 106 represented by an O-ring is assembled to the upstream outer peripheral portion (diameter direction outer side) 114 of the fixed core 101, and a protection member 107 for protecting the seal member 106 is assembled to the downstream side thereof. The sealing member 106 seals the gap between the inner peripheral surface of the fuel pipe (not shown) and the upstream outer peripheral portion 114 of the fixed core 101 to prevent leakage of fuel flowing through the fuel pipe.

[coil]
Next, the electromagnetic coil 108 will be explained. The electromagnetic coil 108 is wound around a cylindrical coil bobbin. The electromagnetic coil 108 is wound around a coil bobbin and arranged so as to cover part of the outer peripheral surface of the large diameter portion 102 a of the nozzle holder 102 and part of the outer peripheral surface of the tip of the fixed core 101 . The winding start and winding end portions of the electromagnetic coil 108 are connected to power supply terminals of a connector 136 of a connecting portion 135 to be described later via wiring (not shown). A housing 109 is fixed around the outer circumference of the electromagnetic coil 108 .

[housing]
The housing 109 is formed in a cylindrical shape with a bottom. A fitting hole 109a is formed in the bottom portion of the housing 109, which is the tip portion in the axial direction Da. The fitting hole 109a is formed in the central portion of the bottom. The nozzle holder 102 is inserted into the fitting hole 109a. The opening edge of the fitting hole 109a and the outer peripheral surface of the nozzle holder 102 are welded, for example, over the entire circumference. The nozzle holder 102 is thereby fixed to the housing 109 .

Further, the housing 109 is arranged so as to surround the distal end side of the fixed core 101 , the coil bobbin, and the outer periphery of the electromagnetic coil 108 . The inner peripheral surface of the housing 109 faces the nozzle holder 102 and the electromagnetic coil 108 and forms an outer peripheral yoke portion. Thus, a magnetic circuit including the fixed core 101, the anchor 110, the nozzle holder 102 and the housing 109 is formed around the electromagnetic coil .

[Connection part]
The connecting portion 135 is made of resin. The connecting portion 135 is filled between the fixed core 101 and the housing 109 . Further, the connection portion 135 covers the outer peripheral surface of the fixed core 101 excluding the rear end portion of the fixed core 101 on the rear end side of the housing 109 in the axial direction Da. The connecting portion 135 is then molded to form a connector 136 having terminals for power supply. The terminals are connected to connection terminals of a plug (not shown). The fuel injector 100 is thereby connected to a high voltage power supply or battery power supply.

In addition, an EDU (drive circuit) 121 as a driving device for driving the fuel injection device 100 and an ECU (engine control unit) 120 that controls the EDU 121 are connected to the fuel injection device 100 .

The ECU 120 receives signals from various sensors indicating the state of the engine (internal combustion engine, not shown) to which fuel is to be injected by the fuel injection device 100, and determines an appropriate driving pulse width and injection timing according to the operating conditions of the engine. perform the calculation of A drive pulse output from the ECU 120 is input to the EDU 121 of the fuel injection device 100 through the signal line 123 .

The EDU 121 controls the voltage applied to the electromagnetic coil 108 of the fuel injection device 100 to supply current to the electromagnetic coil 108 . Also, the ECU 120 communicates with the EDU 121 through a communication line 122 and controls the drive pulse according to the pressure of the fuel supplied to the fuel injection device 100 and operating conditions. Then, it is possible to switch the drive voltage (current) generated by the EDU 121 . The EDU 121 can change the control constant through communication with the ECU 120, and the current waveform changes according to the control constant.

The ECU 120 and EDU 121 may be configured as an integral part. That is, the drive device for driving the fuel injection device 100 may be a device that generates a drive voltage for the fuel injection device 100, and for example, the ECU 120 and the EDU 121 may be integrated to form a drive device. Alternatively, the EDU 121 alone may constitute the drive device as exemplified in this embodiment.

1-2. Detailed Configuration of Valve Member and Anchor Next, the detailed configuration of the valve member 104 and the anchor 110 will be described with reference to FIGS. 1 and 2. FIG.
FIG. 2 is a cross-sectional view showing an enlarged view of spacer 125 and anchor 110 in fuel injection device 100. As shown in FIG. In addition, FIG. 2 shows the closed state.

As shown in FIG. 1, the plunger rod 113 is configured by a cylindrical rod-shaped member. As shown in FIG. 2, the plunger rod 113 is inserted through the insertion hole 110c of the anchor 110 and arranged in the communication hole 102c of the nozzle holder 102 (see FIG. 1).
As shown in FIG. 1, a valve body 117 is provided at the tip of the plunger rod 113 in the axial direction Da. The valve body 117 is supported by a guide member 105 provided on the nozzle holder 102 so as to be movable along the axial direction Dab. The valve body 117 releasably contacts the valve seat 103 a of the injection hole forming member 103 to open and close the injection hole 112 provided in the injection hole forming member 103 .

Further, as shown in FIG. 2, the plunger rod 113 has an engaging portion 128 that engages with the anchor 110. As shown in FIG. The plunger rod 113 is inserted through the insertion hole 110 c provided in the anchor 110 . The engaging portion 128 is formed closer to the rear end side in the axial direction Da than the anchor 110 . The diameter of the engaging portion 128 is larger than the diameter of the plunger rod 113 and the inner diameter 110b (see FIG. 3B) of the insertion hole 110c. The engaging portion 128 protrudes radially outward from the outer peripheral surface of the plunger rod 113 .

The engaging portion 128 faces the upper end surface of the anchor 110 . When the plunger rod 113 is in the closed state, there is a gap between the lower end surface of the engaging portion 128 on the one end side in the axial direction Da and the distal end portion of the fixed core 101 . Further, the lower end surface of the engaging portion 128 faces the upper end surface of the anchor 110 with a gap therebetween by a spacer 125 which will be described later.

Further, when the valve is opened, that is, when the positions of the anchor 110 and the plunger rod 113 are relatively displaced, the upper end surface of the anchor 110 contacts the lower end surface of the engaging portion 128, and the anchor 110 and the engaging portion 128 are brought into contact with each other. engage. As a result, the plunger rod 113 moves along with the anchor 110 toward the rear end side in the axial direction Da, that is, in the valve opening direction.

A rod head 127 is attached to the rear end side of the engaging portion 128 in the axial direction Da. The rod head 127 is formed in a substantially disc shape. A first spring 118 is in contact with the upper end surface of the rod head 127 . A third spring 126 is in contact with the lower end surface of the rod head 127 . A third spring 126 is interposed between rod head 127 and spacer 125 to bias spacer 125 toward anchor 110 .

A spacer 125 is arranged so as to surround the engagement portion 128 of the plunger rod 113 . The spacer 125 is formed in a substantially cylindrical shape. A third spring 126 abuts on the upper end portion of the spacer 125, which is the end face on the other end side in the axial direction Da. A lower end portion of the spacer 125 on the one end side in the axial direction Da contacts the upper end surface of the anchor 110 .

An engaging portion 128 is accommodated within the spacer 125 . The inner diameter of the spacer 125 is set larger than the diameter of the engaging portion 128 of the plunger rod 113 . Therefore, a gap is formed between the radially outer peripheral surface of the engaging portion 128 and the inner wall surface of the spacer 125 .

In addition, the length of the spacer 125 in the axial direction Da, that is, the length from the lower end portion to the upper surface portion is set longer than the length of the engaging portion 128 in the axial direction Da. Further, the spacer 125 is biased toward the anchor 110 by the third spring 126, so that the upper end surface of the engaging portion 128 contacts the upper surface portion inside the spacer 125 in the valve closed state.

In addition, the plunger rod 113 is inserted into a through hole formed on the rear end side of the spacer 125 in the axial direction Da. The inner diameter of the through hole is set larger than the diameter of the plunger rod 113 .

Here, the anchor 110 is biased toward the fixed core 101 side by the biasing force of the second spring 124 . Therefore, the upper end surface of the anchor 110 contacts the lower end of the spacer 125 . The biasing force of the second spring 124 is set smaller than the biasing force of the third spring 126 . Therefore, the anchor 110 is biased toward the distal end side in the axial direction Da by the third spring 126 via the spacer 125 . Thereby, the movement of the anchor 110 toward the rear end in the axial direction Da, that is, the movement in the valve opening direction is restricted by the spacer 125 and the third spring 126 .

In addition, when the valve is closed, the engagement portion 128 of the plunger rod 113 abuts against the upper surface of the spacer 125, so that the spacer 125 is placed at a predetermined position (reference position). The lower end portion of the spacer 125 contacts the upper end surface of the anchor 110 while the spacer 125 is arranged at the reference position. Thereby, a preliminary stroke can be provided between the lower end surface of the engaging portion 128 and the upper end surface of the anchor 110 .

Also, as described above, when the plunger rod 113 is in the valve closed state, there is a gap between the lower end surface of the engaging portion 128 and the tip portion of the fixed core 101 .

In this example, an example in which the third spring 126 is provided has been described, but the present invention is not limited to this, and the third spring 126 may not be provided.

Anchor 110 will now be described with reference to FIGS. 3A and 3B.
3A is a cross-sectional view taken along the line AA' shown in FIG. 2. FIG. 3B is a cross-sectional view of anchor 110. FIG.
As shown in FIGS. 3A and 3B, the insertion hole 110c of the anchor 110 is formed at a position eccentric to the centerline 110ac of the outer diameter 110a of the anchor 110. As shown in FIGS. Further, the center line 110ac of the outer diameter 110a of the anchor 110 is located at a position shifted leftward from the center line 102ac of the nozzle holder 102 by the length g1. A center line 110bc of the inner diameter 110b (insertion hole 110c) of the anchor 110 is formed at a position shifted rightward from the center line 102ac of the nozzle holder 102 by a length g2. Therefore, the inner diameter 110b (insertion hole 110c) of the anchor 110 is eccentric to the length g1+g2 with the outer diameter 110a of the anchor 110 as a reference.

Therefore, a gap 201 is formed between the insertion hole 110c of the anchor 110 and the valve member 104, as shown in FIG. 3A. A gap 202 is formed between the outer diameter 110 a of the anchor 110 and the valve member 104 .

Next, the amount of eccentricity of the anchor 110 will be described with reference to FIGS. 4A and 4B.
4A and 4B are explanatory diagrams showing the amount of eccentricity of the anchor 110. FIG. 4A shows a case where the eccentricity is large, and FIG. 4B shows a case where the eccentricity is small.

4A and 4B, the radius of the valve member 104 is Rr, the diameter (inner diameter) of the insertion hole 110c of the anchor 110 is Rai, the outer diameter of the anchor 110 is Rao, and the inner diameter of the receiving recess 102b of the nozzle holder 102 is Rni. .

As described above, the anchor 110 is arranged at an eccentric position with respect to the nozzle holder 102 and the valve member 104. Therefore, when the anchor 110 moves in a direction perpendicular to the axial direction Da, a biasing force acts on the rod head 127 and the guide member 105 in a direction perpendicular to the axial direction Da. When the valve member 104 moves in this state, wear progresses only in the urged portion. As a result, the valve seat 103a may be unevenly worn, leading to a valve opening failure.

The example shown in FIG. 4A is a diagram showing an example in which the amount of eccentricity of the anchor 110 is large. If the eccentricity is greater than the example shown in FIG. 4A, the anchor 110 will force the valve member 104 to the right. As for the amount of eccentricity g1+g2, a rightward biasing force acts on the valve member 104 from the anchor 110 when the relationship of the following formula 1 is established.
[Formula 1]
g1+g2>(Rni−Rao)+(Rai−Rr)

The example shown in FIG. 4B is a diagram showing an example in which the amount of eccentricity of the anchor 110 is small. If the amount of eccentricity is smaller than the example shown in FIG. 4B, the anchor 110 will push the valve member 104 leftward. As for the amount of eccentricity g1+g2, a leftward biasing force acts on the valve member 104 from the anchor 110 when the relationship of the following formula 2 is established.
[Formula 2]
g1+g2<(Rni-Rao)-(Rai-Rr)

Therefore, in order for the anchor 110 to come into contact with the valve member 104 and eliminate the urging force on the valve member 104, the eccentricity g1+g2 of the anchor 110 preferably satisfies the relationship of Equation 3 below. As a result, uneven wear of the valve seat 103a can be suppressed, and the occurrence of valve closing failure can be prevented.
[Formula 3]
(Rni-Rao)-(Rai-Rr)<g1+g2<(Rni-Rao)+(Rai-Rr)

1-3. Operation Example of Fuel Injection Apparatus Next, an operation example of the fuel injection apparatus 100 having the configuration described above will be described with reference to FIG.
FIG. 5 is a cross-sectional view showing an enlarged view of spacer 125 and anchor 110 when the valve opening operation is completed.

When the electromagnetic coil 108 is energized by the ECU, magnetic flux flows in the magnetic circuit formed by the fixed core 101 , the anchor 110 , the nozzle holder 102 and the housing 109 .
Then, a magnetic attractive force that attracts the anchor 110 is generated in the fixed core 101 . When the magnetic attraction force of fixed core 101 exceeds the biasing force of third spring 126 , anchor 110 presses spacer 125 and moves toward fixed core 101 . Therefore, the anchor 110 moves toward the rear end side in the axial direction Da. During this time, the tip of the plunger rod 113 is in contact with the valve seat 103 a of the injection hole forming member 103 .

As the anchor 110 moves toward the rear end side in the axial direction Da, the upper end surface of the anchor 110 approaches the lower end surface of the engaging portion 128 of the plunger rod 113 . Therefore, the gap between the upper end surface of the anchor 110 and the lower end surface of the engaging portion 128 is zero.

Furthermore, the size of the gap (magnetic attraction gap) between the anchor 110 and the fixed core 101 is reduced by the amount that the anchor 110 moves toward the rear end side in the axial direction Da. Furthermore, since the spacer 125 also moves toward the rear end in the axial direction Da, a gap is generated between the upper surface of the spacer 125 and the upper end surface of the engaging portion 128 .

Also, there is a gap between the anchor 110 and the engaging portion 128 immediately before the valve opening operation is started. Therefore, the anchor 110 abuts the engaging portion 128 after moving through the gap. As a result, the anchor 110 accelerates until it abuts against the engaging portion 128, that is, while moving through the gap. As a result, the anchor 110 can be brought into contact with the engaging portion 128 while the anchor 110 is accelerated.

In this way, the force applied from the anchor 110 to the plunger rod 113 via the engaging portion 128 can be increased, and the plunger rod 113 can quickly start moving toward the rear end side in the axial direction Da. As a result, the valve opening operation of the plunger rod 113 can be started quickly.

Also, as the upper end surface of the anchor 110 approaches the lower end surface of the engaging portion 128, a region 200 (see FIG. 2) formed by the lower end surface of the engaging portion 128, the upper end surface of the anchor 110, and the spacer 125 (see FIG. 2). volume decreases sharply. In the conventional fuel injection device, since the region 200 is a closed space, the pressure in the region 200 fluctuates greatly due to the change in the volume of the region 200 . In addition, the dimension of the region 200 varies from individual fuel injection device to fuel injection device due to manufacturing variations of the fuel injection device. Therefore, the amount of change in the pressure in the region 200 varies from individual to individual, and the valve opening timing and valve opening speed of the plunger rod 113 also vary. As a result, in the conventional fuel injection device, the injection amount varies from one fuel injection device to another.

When the valve is in the open state (full lift state), the anchor 110 abuts against the engaging portion 128 of the plunger rod 113 and a gap is formed between the upper end surface of the engaging portion 128 and the upper surface portion of the spacer 125 . When the valve is changed from the open state to the closed state, the volume of the region 200 decreases, so the pressure in the region 200 increases. As a result, the pressure acting on the plunger rod 113 changes, and the valve closing operation of the plunger rod 113 is also affected.

In contrast, in the fuel injection device 100 of the present embodiment, the anchor 110 is arranged at a position eccentric to the valve member 104 and the nozzle holder 102 to form the gap 201 between the valve member 104 and the insertion hole 110c. doing. As a result, fuel (fluid) in region 200 flows into gap 201 formed between valve member 104 and insertion hole 110c. As a result, it is possible to suppress pressure fluctuations caused by fluctuations in the volume of the region 200 . As a result, when the engaging portion 128 and the anchor 110 approach each other, the anchor 110 can be smoothly brought into contact with the engaging portion 128 without being affected by pressure fluctuations in the region 200 .

Furthermore, even if the volume of the region 200 varies from individual to individual, variations in the plunger rod 113, the valve opening timing, and the valve opening speed can be suppressed. As a result, variations in the injection amount for each fuel injection device 100 can be suppressed.

Further, when the anchor 110 moves to the rear end side in the axial direction Da, the anchor 110 and the engaging portion 128 are engaged. At this time, the length of the gap between the engaging portion 128 and the tip of the fixed core 101 is reduced. Then, the valve member 104 moves to the rear end side in the axial direction Da together with the anchor 110 .

As shown in FIG. 5, when the anchor 110, the spacer 125 and the plunger rod 113 move further toward the rear end in the axial direction Da, the tip of the valve body 117 separates from the valve seat 103a of the injection hole forming member 103. The valve is opened in which the injection hole 112 is opened. As a result, fuel injection from the injection hole 112 is started.

In addition, since the upper end surface of the anchor 110 abuts against the distal end portion of the fixed core 101, movement of the anchor 110 toward the rear end side in the axial direction Da is restricted. The plunger rod 113 moves toward the rear end side in the axial direction Da by inertia force, but is pushed back by the biasing force of the first spring 118 . Therefore, the plunger rod 113 stands still while the lower end surface of the engaging portion 128 is in contact with the upper end surface of the anchor 110 . As a result, the plunger rod 113 moves by a predetermined stroke amount, and the valve is in an open stationary state.

In the valve open stationary state, the anchor 110 is attracted to the fixed core 101 by magnetic attraction force, and the valve member 104 is biased in the valve closing direction by the biasing force of the first spring 118 . Therefore, the anchor 110 and the plunger rod 113 abut each other and are integrated. That is, the lower end surface of the engaging portion 128 of the plunger rod 113 contacts the upper end surface of the anchor 110, and the size of the gap becomes zero.

Furthermore, since the biasing force of the third spring 126 is smaller than the magnetic attraction force, the third spring 126 cannot push back the anchor 110 toward the distal end side in the axial direction Da via the spacer 125 . Therefore, the lower end of the spacer 125 contacts the upper end surface of the anchor 110, and the gap between the upper end surface of the engaging portion 128 and the upper surface of the spacer 125 is maintained.
Furthermore, since the anchor 110 is in contact with the fixed core 101, the size of the gap between the upper end surface of the anchor 110 and the distal end portion of the fixed core 101 is zero.

When the drive pulse is turned off in the valve open state (full lift state) shown in FIG. 5, the energization to the electromagnetic coil 108 is cut off. Therefore, the magnetic attractive force generated between the anchor 110 and the fixed core 101 disappears. Then, when the magnetic attraction force becomes smaller than the biasing force of the first spring 118, the valve member 104 starts to move toward the distal end side in the axial direction Da, that is, in the valve closing direction. After the valve member 104, which has started to move in the valve closing direction, is displaced together with the anchor 110, the tip of the valve element 117 is seated on the valve seat 103a. As a result, the valve is returned to the closed state shown in FIG. 2, and fuel injection by the fuel injection device 100 is stopped.

Furthermore, during the valve closing operation, the lower end surface of the engaging portion 128 separates from the upper end surface of the anchor 110, so the volume of the region 200 increases sharply. At this time, fuel (fluid) flows into the region 200 from the gap 201 formed between the valve member 104 and the insertion hole 110c. As a result, pressure fluctuations in the region 200 can be suppressed even during the valve closing operation. As a result, it is possible to realize a stable valve closing operation, and to suppress variations in the injection amount.

Furthermore, as the anchor 110 moves toward the tip side in the axial direction Da, the volume of the space 203 formed between the anchor 110, the nozzle holder 102, and the fixed core 101 increases. Fuel flows into the space 203 through the gap 202 between the anchor 110 and the nozzle holder 102 .

At this time, the anchor 110 is in close contact with the nozzle holder 102 due to the residual magnetic flux.
Then, the anchor 110 slides toward the distal end side in the axial direction Da while maintaining a tight contact state with the nozzle holder 102 . At this time, the variation in fluid resistance is caused by the variation in size of the gap 202, and the narrower the gap 202, the greater the variation in fluid resistance. As a result, variations occur in the descending speed of the anchor 110 (valve closing start timing).

On the other hand, in the fuel injection device 100 of this example, the center line 110ac of the outer diameter 110a of the anchor 110 is arranged at a position eccentric to the center line 102ac of the nozzle holder 102. This makes it possible to secure a wide gap 202 on one side (the right side in the example shown in FIG. 3) between the anchor 110 and the nozzle holder 102 . Furthermore, on the side opposite to the gap 202 between the anchor 110 and the nozzle holder 102 , a sliding portion where the anchor 110 comes into close contact with the nozzle holder 102 can be secured. As a result, while the anchor 110 is brought into close contact with the nozzle holder 102 and reliably slid, by setting the gap 202 large, it is possible to suppress variations in the fluid force.

2. Second Embodiment Next, a fuel injection device according to a second embodiment will be described with reference to FIG.
FIG. 6 is a sectional view showing the anchor and nozzle holder of the fuel injection device according to the second embodiment.

The fuel injection device according to the second embodiment differs from the fuel injection device according to the first embodiment in the shape of the anchor. Therefore, the parts common to the fuel injection device 100 according to the first embodiment are denoted by the same reference numerals, and redundant explanations are omitted.

As shown in FIG. 6, the anchor 110A is formed by two arcs with different curvatures. That is, the anchor 110A includes a first arc portion 110f having a radius of curvature smaller than the inner diameter of the housing recess 102b of the nozzle holder 102 and a second arc portion 110g having a radius of curvature larger than the inside diameter of the housing recess 102b of the nozzle holder 102. have. The first arc portion 110f and the second arc portion 110g are formed continuously along the circumferential direction of the anchor 110A.

Also, the insertion hole 110c formed in the anchor 110A is formed in the center of the anchor 110A. The inner diameter of the insertion hole 110 c is formed sufficiently larger than the diameter of the valve member 104 .

Also in the anchor 110A having such a shape, it is possible to ensure a large gap 201 between the insertion hole 110c and the valve member 104, like the anchor 110 according to the first embodiment. Furthermore, a large gap 202 between the anchor 110A and the nozzle holder 102 can be ensured.

Also, the anchor 110A contacts the nozzle holder 102 at a point (inflection point) C and a point (inflection point) D which are intersection points of the first arc portion 110f and the second arc portion 110g. Here, the magnitude of the radially outward electromagnetic force acting on the anchor 110 is inversely proportional to the square of the distance to the gap 202 . Therefore, the anchor 110A slides between points C and D where the gap with the nozzle holder 102 is the smallest.

When the anchor 110A exerts a radially outward force due to the electromagnetic force, the force of the first vector 206a acts on the nozzle holder 102 at point C, and the force of the second vector 207a acts on the nozzle holder 102 at point D. . The first vector 206a can be divided into a first force component 206b directed in a first direction and a second force component 206c directed in a second direction orthogonal to the first direction. Similarly, the second vector 207a can be divided into a first force component 207b directed in the first direction and a second force component 207c directed in the second direction.

Here, since the first force component 206b of the first vector 206a and the first force component 207b of the second vector 207a are directed in different directions, they can be canceled. As a result, the pressing forces at points C and D become

vectors

206d and 207d consisting of the second force component 206c and the second force component 207c. In this way, since the pressing force acting on the nozzle holder 102 can be reduced by the anchor 110A, the amount of wear of the anchor 110 and the nozzle holder 102 can be suppressed.

The rest of the configuration is the same as the fuel injection device 100 according to the first embodiment, so description thereof will be omitted. A fuel injection device having such an anchor 110A can also provide the same effects as the fuel injection device 100 according to the first embodiment described above.

Further, in the fuel injection device according to the second embodiment, the shape of the anchor 110A may be elliptical, or the shape of the accommodation recess 102b of the nozzle holder 102 may be formed of a plurality of arcs with different curvatures. good. The shape of the anchor 110</b>A may be any shape that has at least one portion where the radius of curvature is larger than the inner diameter of the nozzle holder 102 .

3. Third Embodiment Next, a fuel injection device according to a third embodiment will be described with reference to FIG.
FIG. 7 is a sectional view showing the anchor and nozzle holder of the fuel injection device according to the second embodiment.

The fuel injection device according to the third embodiment differs from the fuel injection device according to the first embodiment in the shape of the anchor. Therefore, the parts common to the fuel injection device 100 according to the first embodiment are denoted by the same reference numerals, and redundant explanations are omitted.

As shown in FIG. 7, the anchor 110B is formed of two circles with different curvatures, similar to the anchor 110A according to the second embodiment. That is, the anchor 110A includes a first arc portion 110m having a radius of curvature smaller than the inner diameter of the housing recess 102b of the nozzle holder 102 and a second arc portion 110k having a radius of curvature larger than the inside diameter of the housing recess 102b of the nozzle holder 102. have.

The curvature of the anchor 110B changes at points C and D, which are intersections of the first arc portion 110m and the second arc portion 110k. Also, the distance Ra1 from the center of the anchor 110B to the point C is set shorter than the distance Ra2 from the center of the anchor 110B to the point D (Ra1<Ra2).

As described above, the magnitude of the radially outward electromagnetic force acting on anchor 110 is inversely proportional to the square of the distance from gap 202, so anchor 110B first contacts nozzle holder 102 at point D. do. Anchor 110B then contacts nozzle holder 102 at point C. As shown in FIG. Therefore, a torque is generated in the anchor 110B with the vicinity of the center of the anchor 110B as the fulcrum of rotation. This torque slightly rotates the anchor 110B, and by repeating the valve opening operation and the valve closing operation, the sliding position of the anchor 110B with respect to the nozzle holder 102 can be changed. As a result, it is possible to prevent only a part of the nozzle holder 102 from being worn locally.

The rest of the configuration is the same as the fuel injection device 100 according to the first embodiment and the fuel injection device according to the second embodiment, so description thereof will be omitted. Even with a fuel injection device having such an anchor 110B, the same effects as those of the fuel injection device 100 according to the first embodiment and the fuel injection device according to the second embodiment can be obtained. can.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and various modifications are possible without departing from the gist of the invention described in the claims.

In this specification, words such as "parallel" and "perpendicular" are used, but these do not strictly mean only "parallel" and "perpendicular", but include "parallel" and "perpendicular". Furthermore, it may be in a "substantially parallel" or "substantially orthogonal" state within the range where the function can be exhibited.

100... Fuel injection device 101... Fixed core 101a... Through hole 101b... Tip part 102... Nozzle holder 102a... Large diameter part 102b... Concave part 102c... Communication hole 103... Injection hole forming member 103a Valve seat 104 Valve member 105 Guide member 108 Electromagnetic coil 109 Housing 109a Fitting hole 110 Anchor 110c Insertion hole 110d Eccentric through hole 111 Fuel supply port 112... Injection hole 113... Plunger rod 117... Valve element 118... First spring 124... Second spring 125... Spacer 126... Third spring 127... Rod head 128... Engaging

portion

201, 202... Gap part

Claims

a nozzle holder provided with an injection hole forming member;
a fixed core disposed in the nozzle holder;
an anchor facing the fixed core and arranged in a housing recess provided in the nozzle holder;
a valve member having a valve body for opening and closing the injection hole provided in the injection hole forming member;
The anchor is formed with an insertion hole through which the valve member is inserted,
A fuel injection device, wherein gaps through which a fluid can pass are formed between the anchor and the nozzle holder and between the insertion hole and the valve member.
2. The fuel injection device according to claim 1, wherein a center line of said insertion hole is formed at a position eccentric with respect to a center line of an outer diameter of said anchor.
The fuel injection device according to claim 2, wherein the centerline of the outer diameter of the anchor is formed at a position eccentric with respect to the centerline of the nozzle holder.
The amount of eccentricity with respect to the outer diameter of the anchor in the insertion hole satisfies the following formula: (inner diameter of the nozzle holder - outer diameter of the anchor) - (inner diameter of the insertion hole - radius of the valve member) < eccentricity < ( Inner diameter of the nozzle holder - Outer diameter of the anchor) + (Inner diameter of the insertion hole - Radius of the valve member)
4. A fuel injection system according to claim 3.
The fuel injection device according to claim 1, wherein the outer diameter of the anchor is formed by a plurality of arcs with different curvatures.
The fuel injection device according to claim 5, wherein the radius of curvature of at least one arc of the outer diameter of the anchor is larger than the inner diameter of the nozzle holder.