WO2021192529A1

WO2021192529A1 - Fuel injection device

Info

Publication number: WO2021192529A1
Application number: PCT/JP2021/001183
Authority: WO
Inventors: 真士菅谷; 威生三宅; 泰介杉井; 拓矢渡井
Original assignee: 日立Astemo株式会社
Priority date: 2020-03-26
Filing date: 2021-01-15
Publication date: 2021-09-30
Also published as: JP2023062216A

Abstract

The purpose of the present invention is to provide a fuel injection device which can stably inject fuel by enabling stable sliding between a valve member and a sliding surface on which the valve member slides.　This fuel injection device 100 has a valve member 104 having, on one end side thereof, a valve body that opens/closes a flow path, and having, on the other end side thereof, a guided part 127d that is guided by making sliding contact with a guide part formed on an inner peripheral section 101a of a stator core 101. The valve member 104 has a curved part 127f which is provided on the side opposite to said one end side of the valve member 104 with respect to the guided part 127d, and which curves radially inward toward the side opposite to said one end side of the valve member 104 from the side of the guided part 127d. The radius of curvature R127f of the curved part 127f has a magnitude of 40% or greater with respect to the inner radius R101a of the guide part 101a formed on the stator core 101.

Description

Fuel injection device

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

As a background technology in this technical field, the fuel injection valve described in the pamphlet of International Publication No. 2016/042896 (Patent Document 1) is known. The fuel injection valve of Patent Document 1 includes a valve member, an anchor that can be displaced relative to the valve member, and a magnetic core having a through hole formed therein, and anchors are used as valve members on both the anchor and the valve member. On the other hand, in a fuel injection valve provided with an engaging portion that engages and regulates the displacement of the anchor in the valve opening direction when displaced in the valve opening direction, the engaging portion on the valve member side and the engaging portion on the anchor side. A gap forming member that forms a gap between the two, and an urging spring that urges the gap forming member in the valve closing direction are provided, and the outer diameter of the gap forming member, the outer diameter of the urging spring, and the maximum outer diameter of the valve member are provided. The diameter is made smaller than the inner diameter of the through hole (see summary).

This fuel injection valve has a first spring that urges the plunger rod in the valve closing direction, a second spring that urges the anchor in the valve opening direction, and a third spring that urges the anchor in the valve closing direction from the fixed core side. (See paragraphs 0017 and 0022). The plunger rod is urged in the valve closing direction by the urging force of the first spring, and the valve body provided at one end of the plunger rod comes into contact with the valve seat (see paragraph 0058). On the other hand, a cap is provided at the other end of the plunger rod (see paragraph 0016). The upper end surface of the cap constitutes a spring seat with which the first spring abuts (paragraph 0023).

Further, the cap has an outer peripheral surface that abuts on the inner peripheral surface of the through hole of the fixed core and is configured to slide with respect to the inner peripheral surface of the through hole at the time of the on-off valve (see paragraph 0114). That is, the inner peripheral surface of the through hole serves as a guide surface for guiding the movement of the outer peripheral surface of the cap in the on-off valve direction (paragraph 0115).

International Publication No. 2016/042896 Pamphlet

In the fuel injection valve (fuel injection device) of Patent Document 1, the inner peripheral surface of the through hole of the fixed core is configured to guide the movement of the cap as a guide surface. A sliding gap is formed between them. By forming this sliding gap, the central axis of the cap is inclined with respect to the central axis of the inner peripheral surface of the through hole serving as the guide surface.

Further, since the upper end surface of the cap constitutes a spring seat with which the first spring abuts, the first spring exerts a lateral force (in the direction perpendicular to the valve axis) with respect to the plunger rod when urging the plunger rod. Force) is applied. Due to this lateral force, the outer peripheral corner of the cap is strongly pressed against the inner peripheral surface of the through hole of the fixed core. Hereinafter, the members forming an integral structure with the valve body, including the valve body, the plunger rod, the cap, etc., will be referred to as a valve member.

In this case, the inclination of the valve member (cap) causes the sliding area between the outer peripheral corner of the cap and the inner peripheral surface of the through hole to become insufficient, resulting in a large sliding resistance on the sliding surface. Become. Further, the lateral force generated by the first spring increases the sliding resistance on the sliding surface. As a result, the inner peripheral surface of the through hole is worn due to repeated on-off valves. Further, when the sliding resistance of the sliding surface becomes large, the delay of the valve closing operation becomes large, so that the fuel injection amount becomes large and stable fuel injection is hindered.

An object of the present invention is to provide a fuel injection device capable of stably injecting fuel by enabling stable sliding between a valve member and a sliding portion on which the valve member slides. be.

In order to achieve the above object, the fuel injection device in the present invention is
A valve body for opening and closing the flow path is provided on one end side, and a guided portion provided on the other end side and guided by sliding contact with a guide portion formed on the inner peripheral portion of the fixed core is provided. A fuel injection device having a valve member
It is provided on the side opposite to the side of one end of the valve member with respect to the guided portion, and bends inward in the radial direction from the side of the guided portion toward the side opposite to the side of one end of the valve member. Has a curved part,
The radius of curvature of the curved portion has a size of 40% or more with respect to the inner radius of the guide portion of the fixed core.
Further, in order to achieve the above object, the fuel injection device in the present invention is used.
A valve body for opening and closing the flow path is provided on one end side, and a guided portion provided on the other end side and guided by sliding contact with a guide portion formed on the inner peripheral portion of the fixed core is provided. A fuel injection device having a valve member
It is provided on the side opposite to the side of one end of the valve member with respect to the guided portion, and bends inward in the radial direction from the side of the guided portion toward the side opposite to the side of one end of the valve member. Has a curved part,
The curved portion is formed so that the axial length is larger than the axial length of the guided portion.

According to the present invention, it is possible to provide a fuel injection device capable of stably injecting fuel by enabling stable sliding between a valve member and a sliding surface on which the valve member slides. can. Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is sectional drawing which shows typically the whole structure of the fuel-injection apparatus which concerns on one Example of this invention. It is a partially enlarged view of FIG. 1, and is the figure which shows the state (valve closed state) in which the drive voltage (current) is not applied to the electromagnetic coil of a fuel injection device. It is a figure explaining the increase of the fuel injection amount due to the delay of the valve closing operation of a valve member. It is a figure which showed schematicly about the valve member which concerns on one Example of this invention. It is sectional drawing which enlarges and shows the vicinity of the guided member (rod head) in which a curved portion is formed. It is a figure which shows an example of the calculation result of the surface pressure (Hertz surface pressure) which concerns on the inner peripheral surface when the guided portion of a valve member is pressed against the inner peripheral surface of a magnetic core (fixed core). It is a conceptual diagram explaining the fuel flow in the vicinity of the 1st spring and the guided member (rod head).

Hereinafter, examples of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a cross-sectional view schematically showing the overall configuration of the fuel injection device 100 according to the embodiment of the present invention. The cross section shown in FIG. 1 is a cross-sectional view parallel to the central axis 100a and including the central axis 100a.

The fuel injection device 100 is, for example, a fuel injection device for an in-cylinder direct injection type gasoline engine. In this embodiment, an electromagnetically driven fuel injection device that electromagnetically drives the valve body will be described as an example, but the valve member 104 and the winding spring (first spring) that urges the valve member 104 described below will be described. The present invention can be applied to a fuel injection device of another drive system as long as it is a fuel injection device including 118. The present invention is also applicable to a fuel injection device for a port injection engine and a fuel injection device for a diesel engine.

In the direction along the central axis 100a of the fuel injection device 100, the side closer to the fuel injection hole 112 (lower side in FIG. 1) is defined as the downstream side, and the side closer to the fuel supply port 111 (upper side in FIG. 1) is defined as the upstream side. Will be explained. This is based on the structure of the fuel passage formed inside the fuel injection device 100, and the fuel flows from the fuel supply port 111 toward the fuel injection hole 112 through the inside of the fuel injection device 100 substantially along the central axis 100a. It flows. In this embodiment, the centers of the valve member 104, the anchor 110, the first spring 118, the adjuster 119, the third spring 124, the magnetic core 101, the plunger rod 113, the intermediate member 125, the second spring 126, and the rod head 127. The axes are arranged so as to coincide with the central axis 100a. Therefore, the axial center (valve axial center) of the plunger rod 113 is along the central axis 100a, and the on-off valve direction, which is the moving direction of the valve member 104, is along the central axis 100a.

The end portion on the fuel injection hole 112 side (downstream side) may be referred to as the tip end portion, and the end portion on the fuel supply port 111 side (upper side in FIG. 1) may be referred to as the base end portion. Further, in the following description, the vertical direction may be specified, but this vertical direction is based on the vertical direction of FIG. 1, and the vertical direction in the state where the fuel injection device 100 is mounted is not specified. No.

The fuel injection device 100 is connected to an EDU (drive circuit) 121, which is a drive device for driving the fuel injection device 100, and an ECU (engine control unit) 120, which controls the EDU 121.

In the ECU 120, signals indicating the state of the engine (internal combustion engine: not shown) to be fuel-injected by the fuel injection device 100 are taken in from various sensors, and the appropriate drive pulse width and injection timing are taken according to the operating conditions of the engine. Perform the calculation of. The 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 a current to the electromagnetic coil 108. Further, the ECU 120 communicates with the EDU 121 through the communication line 122, controls the drive pulse according to the pressure of the fuel supplied to the fuel injection device 100 and the operating conditions, and can switch the drive voltage (current) generated by the EDU 121. It is possible. The EDU 121 can change the control constant by communicating 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 any device that generates the drive voltage of the fuel injection device 100, and for example, the ECU 120 and the EDU 121 may be integrated to form the drive device. However, as illustrated in this embodiment, the drive device may be configured by the EDU 121 alone.

The fuel injection device 100 includes a magnetic core (fixed core) 101 having a fuel supply port 111 to which fuel is supplied, a nozzle holder 102 provided on the downstream side of the magnetic core 101, and a downstream end portion of the nozzle holder 102. It has an injection hole member 103, which is located at the tip end portion) and forms a fuel injection hole 112. The injection hole member 103 is inserted inside the nozzle holder 102, and is welded and fixed to the tip of the nozzle holder 102 along the outer peripheral portion of the tip surface.

The injection hole member 103 is formed with a valve seat 103a to which the valve body 117 formed at one end of the valve member 104 comes into contact with each other. The injection hole member 103 seals the fuel when the valve body 117 is seated.
The valve body 117 abuts on the valve seat 103a to seal the fuel, and separates from the valve seat 103a to allow the flow of fuel. That is, the valve body 117 and the valve seat 103a cooperate to open and close the fuel passage.

Further, inside the injection hole member 103, a guide member 105 for guiding the outer peripheral surface of the valve body 117 configured at the downstream tip portion of the plunger rod 113 is fixed by press fitting or plastic coupling. The guide member 105 may be formed integrally with the injection hole member 103.

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

An electromagnetic coil 108 is provided on the outer peripheral portion (diameterally outer side) on the upstream side of the nozzle holder 102, and a housing 109 is provided on the outer peripheral side thereof so as to include the electromagnetic coil 108. A magnetic circuit is formed by the housing 109, the magnetic core 101, and the anchor (movable core) 110.

A groove 115 is formed on the outer peripheral portion (diameterally outside) on the downstream side of the nozzle holder 102, and a seal member 116 represented by a resin chip seal is fitted in the groove 115.

Inside the magnetic core 101 and the nozzle holder 102, a valve member 104, an anchor 110, a first spring 118, a regulator 119, and a third spring 124 are arranged. The valve member 104 adjusts the fuel injection amount by the fuel injection device 100 by moving in the axial direction (direction along the central axis 100a). The anchor 110 receives the attractive force of the magnetic core 101 and pulls up the valve member 104 in the valve opening direction. The anchor 110 is configured to be relatively displaceable in the axial direction (on-off valve direction) with respect to the plunger rod 113. The first spring 118 urges the valve member 104 and the anchor 110 in the downstream direction (valve closing direction). The regulator 119 supports the first spring 118 and adjusts the amount of compression (that is, the urging force) of the first spring 118. The third spring 124 is held by the nozzle holder 102 and urges the anchor 110 and the valve member 104 in the upstream direction (valve opening direction).

The valve member 104 of this embodiment is composed of a plunger rod 113, a valve body 117, an intermediate member 125, a second spring 126, and a rod head 127.

The intermediate member 125 is located near the end of the plunger rod 113 on the base end side (upstream side end side) and has a gap G2 between the anchor 110 and the stepped portion 128 of the plunger rod 113 (see FIG. 2). To form. The second spring 126 urges the anchor 110 to the downstream side via the intermediate member 125. The rod head 127 has seating surfaces for the first spring 118 and the second spring 126. Further, the rod head 127 has a sliding surface 127d (see FIG. 2) that slides facing the through hole 101a formed in the radial central portion of the magnetic core 101 and penetrating in the axial direction. The sliding surface 127d is composed of the outermost peripheral surface of the rod head 127. That is, the rod head 127 is provided at the upstream end of the plunger rod 113 and has a sliding surface 127d that slides in opposition to the through hole 101a of the magnetic core 101.

The inner peripheral surface of the through hole 101a constitutes a guide surface (sliding surface) that supports the upstream end of the plunger rod 113 in the radial direction via the rod head 127 and guides the plunger rod 113 in the on-off valve direction.
The through hole 101a constitutes a fuel passage, and the guide surface of the plunger rod 113 is formed inside the fuel passage of the magnetic core 101. Therefore, hereinafter, the inner peripheral surface of the through hole 101a is referred to as a guide surface (guide portion) or a sliding surface (sliding portion), and the sliding surface 127d is referred to as a guided surface (guided portion) or a sliding surface (guided portion) or a sliding surface (sliding portion). It will be called a sliding part).

In this embodiment, it has a plurality of winding springs supported by the rod head 127. As a plurality of winding springs, a first spring 118 whose one end is supported by the rod head 127 to urge the plunger rod 113 in the valve closing direction (downstream side) and an intermediate member 125 whose one end is supported by the rod head 127. A second spring 126 is provided to urge the valve in the valve closing direction (downstream side). That is, the rod head 127 constitutes a spring receiving portion in the valve member 104.

Here, the configurations of the valve member 104 and the anchor 110 will be described in detail with reference to FIG. FIG. 2 is a partially enlarged view of FIG. 1 and is a diagram showing a state (valve closed state) in which a driving voltage (current) of the fuel injection device 100 is not applied to the electromagnetic coil 108. The cross section shown in FIG. 2 is an enlarged view of the vicinity of the upper end portion of the valve member 104 in the cross-sectional view shown in FIG. Note that FIG. 2 shows a state in which the energization of the electromagnetic drive unit is turned off, the valve body 117 is seated on the valve seat 103a, and the anchor 110 is stationary.

The anchor 110 has a through hole 110c, and the plunger rod 113 of the valve member 104 is configured to insert the inner diameter of the through hole 110c. As a result, the anchor 110 and the valve member 104 are configured to be relatively displaceable in the axial direction.

The plunger rod 113 has a stepped portion 128 at the upstream end. The stepped portion 128 has an outer diameter larger than the diameter of the rod portion 113a penetrating the inner diameter (through hole) 110c of the anchor 110. The stepped portion 128 projects radially outward from the outer peripheral surface of the rod portion 113a in a brim shape. In the anchor 110, the upstream end surface 110a faces the lower end surface (downstream end surface) 128b of the stepped portion 128, and the upstream end surface 110a abuts on the lower end surface 128b of the stepped portion 128 during relative displacement, whereby the plunger rod The relative displacement to the upstream side (valve opening direction) with respect to 113 is regulated.

A protrusion 129 having a diameter smaller than that of the stepped portion 128 is provided above the upper end surface (upstream side end face) 128a of the stepped portion 128, and the upper end surface 129a of the protruding portion 129 is in the downstream direction (stepped portion 128 side). ) Is formed with a recessed hole (recess) 130. The plunger rod 113 is provided with an intermediate member 125 that engages with the stepped portion 128 on the upstream side. A recess 125c is formed on the lower end surface (downstream end surface) 125b of the intermediate member 125 toward the upstream side (upper surface 125a side), and the recess 125c has a diameter (inner diameter) and a depth in which the stepped portion 128 fits. doing. An axial through hole 125d is formed from the bottom surface 125e of the recess 125c to the upper end surface (upstream end surface) 125a of the intermediate member 125. A protrusion 129 is inserted through the through hole 125d.

A second spring 126 is supported on the upstream side of the intermediate member 125, and the upper end surface 125a of the intermediate member 125 constitutes a spring seat with which the downstream end of the second spring 126 abuts.

A rod head 127 is provided at the upstream end of the plunger rod 113. A flange portion 127c projecting in the radial direction is provided at the upper end portion of the rod head 127, and a spring seat is formed in which the upstream end portion of the second spring 126 abuts on the lower surface 127b of the collar portion 127c. The rod head 127 is provided with an upstream projection 131 having a diameter smaller than the inner diameter of the first spring 118. The upstream projection 131 projects upstream from the upper surface 127a of the flange 127c.

The rod head 127 receives the urging force (first spring force) of the first spring 118 from the upper side (upstream side) and the urging force (second spring force) of the second spring 126 from the lower side (downstream side). The first spring force is larger than the second spring force, and as a result, the urging force of the difference between the first spring force and the second spring force is applied to the rod head 127 on the upper end surface 129a of the protrusion 129 of the plunger rod 113. Act towards. Since no force is applied to the rod head 127 in the direction of coming out of the hole 130 of the plunger rod 113, it is sufficient to press-fit and fix the rod head 127 to the hole 130, and it is not necessary to weld the rod head 127.

The intermediate member 125 will be further described.

In the state shown in FIG. 2, the intermediate member 125 receives the urging force of the second spring 126, and the bottom surface 125e of the recess 125c is in contact with the upper end surface 128a of the stepped portion 128 of the plunger rod 113. That is, the size (dimension) of the gap G3 between the bottom surface 125e of the recess 125c and the upper end surface 128a of the stepped portion 128 is zero. The bottom surface 125e of the intermediate member 125 and the upper end surface 128a of the stepped portion 128 form a contact surface where the intermediate member 125 and the stepped portion 128 come into contact with each other.

On the other hand, the anchor 110 receives the urging force (third spring force) of the third spring 124 and is urged toward the magnetic core 101 side. Therefore, the upper end surface (upstream end surface) 110a of the anchor 110 comes into contact with the lower end surface (opening edge of the recess 125a) 125b of the intermediate member 125.
Since the urging force of the third spring 124 is weaker (smaller) than the urging force of the second spring 126, the anchor 110 cannot push back the intermediate member 125 urged by the second spring 126, and the intermediate member 125 and the second spring 126 cannot be pushed back. 2 The spring 126 can stop the upward movement (valve opening direction). The upper end surface 110a of the anchor 110 and the lower end surface 125b of the intermediate member 125 form a contact surface where the anchor 110 and the intermediate member 125 abut, respectively.

The intermediate member 125 has an engaging portion (stepped portion) of the plunger rod 113 when the lower end surface 125b comes into contact with the anchor 110 in a state where the intermediate member 125 is positioned on the upper end surface (reference position) 128a of the stepped portion 128 of the plunger rod 113. A gap G2 (G2> 0) is formed between the lower end surface of the 128) 128b and the contact portion (upper end surface 110a) of the anchor 110. The second spring 126 urges the intermediate member 125 in the valve closing direction so as to position the intermediate member 125 on the upper end surface 128a of the stepped portion 128. In the state of FIG. 2, the lower end surface 128b of the stepped portion 128 and the lower end surface 101b of the magnetic core 101 are separated by the distance of G1 in the valve axis 104a direction.

The intermediate member 125 is positioned at the upper end surface 128a of the stepped portion 128 when the bottom surface 125e of the recess 125 comes into contact with the upper end surface 128a of the stepped portion 128.

Here, the urging forces of the three

springs

118, 126, and 124 explained above will be explained again. Of the first spring 118, the third spring 124, and the second spring 126, the urging force of the first spring 118 is the largest, the urging force of the second spring 126 is the largest, and the urging force of the third spring 124 is the largest. small.

In this embodiment, the upper end surface 110a of the anchor 110 and the lower end surface 101b of the magnetic core 101 are described as being in contact with each other, but either the upper end surface 110a of the anchor 110 or the lower end surface 101b of the magnetic core 101 Alternatively, protrusions may be provided on both of them so that the protrusions and the end faces are in contact with each other or the protrusions are in contact with each other. In this case, the gap G1 + G2 becomes a gap between the contact portion on the anchor 110 side and the contact portion on the magnetic core 101 side.

Since the on-off valve operation in the fuel injection device 100 of this embodiment is the same as that of the fuel injection device of Patent Document 1, the description thereof will be omitted.

The problem of the fuel injection device will be described with reference to FIG. FIG. 3 is a diagram illustrating an increase in the fuel injection amount due to a delay in the valve closing operation of the valve member. FIG. 3A is a conceptual diagram of a drive pulse that controls the fuel injection device 100. The horizontal axis represents the time t, and the vertical axis represents the voltage V (ON, OFF) of the drive pulse. The lower figure (b) is a conceptual diagram showing the position (lift amount) of the valve body 117 in the on-off valve direction, the horizontal axis representing the time t, and the vertical axis representing the position X of the valve body 117 in the on-off valve direction. In FIG. 3, the pulse width (time to be ON) of the drive pulse is Tp.

The first spring 118 is compressed to an arbitrary set length in a state of being assembled to the fuel injection device 100, and exerts a desired urging force (set load) on the valve member 104. At this time, the valve member 104 that has received the urging force of the first spring 118 is stable in a state where the guided portion (outer peripheral surface of the rod head 127) 127d is in contact with the guide portion (inner peripheral surface of the through hole 101a) 101a. A clearance is provided between the guided portion 127d and the guide portion 101a.
Therefore, the valve axis 104a of the valve member 104 and the central axis of the plunger rod 113 are stable in a state of being tilted with respect to the central axis of the inner peripheral surface 101a of the magnetic core 101 which is the guide portion. As a result, the guided portion 127d and the guided portion 101a come into contact with each other at one place in the circumferential direction.

In this case, if the sliding area between the upper edge portion of the outer peripheral surface 127d of the rod head 127 and the inner peripheral surface of the through hole 101a is insufficient, the sliding resistance in the sliding portion increases. Further, the lateral force generated by the first spring 118 increases the sliding resistance in the sliding portion. As a result, the inner peripheral surface of the through hole 101a is worn by repeating the on-off valve.

Further, when the sliding resistance of the sliding portion increases, the delay Tb of the valve closing operation of the valve member 104 increases as shown by Tb', so that the fuel injection amount increases by ΔF, and stable fuel injection occurs. Will be hindered.

On the other hand, in this embodiment, a configuration is provided to suppress an increase in sliding resistance at the sliding portion between the rod head 127 forming the upper end portion of the valve member 104 and the inner peripheral surface of the through hole 101a.
This configuration will be described with reference to FIG. FIG. 4 is a diagram schematically showing a valve member 104 according to an embodiment of the present invention.

The outer peripheral surface of the flange portion 127d of the rod head 127 and the inner peripheral surface of the through hole 101a of the magnetic core 101 serve as a sliding surface that slides with each other, and guides the movement of the valve member 104 in the on-off valve direction. In the following description, reference numerals 101a are attached to both the through hole 101a and its inner peripheral surface.

The flange portion 127c of the rod head 127 is provided with a notch surface 127e, and the flange portion outer peripheral surface 127d facing the inner peripheral surface 101a of the magnetic core 101 is arranged at intervals in the circumferential direction. The notch surface 127e constitutes a fuel passage portion that communicates the fuel passages above and below the collar portion 127c.

The fuel injection device 100 includes a spring receiving portion (rod head) 127 provided on the upper portion of the valve member 104, and the spring receiving portion 127 is an outer periphery guided by an inner peripheral surface (inner peripheral portion) 101a of the cylindrical fuel passage. It has a surface (outer peripheral portion) 127d. The spring receiving portion (rod head) 127 has an upper surface 127a that comes into contact with the lower end portion of the first spring 118 arranged on the upstream side. Since the rod head 127 constitutes the spring receiving portion of the first spring 118, it may be referred to as a spring receiving member. Further, since the rod head 127 constitutes a guided portion (sliding portion) 127d, it may be referred to as a guided member (sliding member). In this case, it does not matter whether the guided member 127 is integrally molded with the valve member 104. However, when the second spring 126 is provided, it is preferable that the guided member 127 is formed separately from the plunger rod 113.

In the following description, the rod head 127 will be referred to as a guided member. The guided member 127 is provided at the upper end of the plunger rod 113 and constitutes the upper end of the valve member 104. The guided member 127 does not need to be provided at the uppermost end of the valve member 104, and another member may be formed above the guided member 127. However, it is preferable that the guided member 127 is provided as close to the uppermost end of the valve member 104 as possible.

The guided member 127 has a curved portion 127f connected to the upper surface 127a on the upper portion of the guided portion 127d. The curved portion 127f forms a curve in the direction along the valve axis (central axis 100a). That is, in this embodiment, the curved portion 127f forms a curved portion (curved surface) between the guided portion 127d of the flange portion 127c and the upper surface 127a. Since this curved portion is composed of the curved portion 127f, reference numeral 127f will be added in the same manner as the curved portion 127f. Since the curved portion 127f constitutes a portion that is in sliding contact with the guide portion 101a and is guided by the guide portion 101a, it can be regarded as a part of the guided portion 127d. In the following description, in order to clearly explain the action and effect of the curved portion 127f, the curved portion 127f will be described separately from the guided portion 127d.

The curved portion 127f will be described with reference to FIGS. 5 to 7.

FIG. 5 is an enlarged cross-sectional view showing the vicinity of the guided member (rod head) 127 on which the curved portion 127f is formed. The cross section shown in FIG. 5 is an enlarged view of the vicinity of the guided member 127 in the cross-sectional view shown in FIG.

The radius of the curved portion 127f gradually decreases (that is, the diameter is reduced) from the guided portion 127d side toward the upper surface 127a side, and the radius reduction rate gradually increases from the guided portion 127d side toward the upper surface 127a side. That is, the curved portion 127f bends inward in the radial direction from the guided portion (sliding surface) 127d side toward the upper side (upper surface 127a side).

In this embodiment, the curved portion 127f is formed so that the lower edge portion is connected to the upper edge portion of the guided portion 127d and the upper edge portion is connected to the outer peripheral edge of the upper surface 127a.

That is, the valve member 104 is a spring receiving portion (upper surface) of the spring member (first spring 118) that urges the valve member 104 in the valve closing direction at the other end on the opposite side to the one end where the valve body 117 is formed. 127a), the curved portion 127f is provided between the spring receiving portion 127a and the guided portion 127d in the axial direction. In this case, it is preferable that the curved portion 127f has an upper edge portion on the side of the spring receiving portion 127a connected to the spring receiving surface constituting the spring receiving portion 127a. Alternatively, the curved portion 127f may have a lower edge portion on the side of the guided portion 127d connected to the guided portion 127d. In this embodiment, in the curved portion 127f, the upper edge portion on the side of the spring receiving portion 127a is connected to the spring receiving surface constituting the spring receiving portion 127a, and the lower edge portion on the side of the guided portion 127d is the guided portion 127d. It is connected to the.

The curved portion 127f is not limited to the configuration of this embodiment, and the central axis of the guided portion 127d (that is, the central axis of the valve member 104) is tilted with respect to the central axis of the inner peripheral surface 101a of the magnetic core 101. The guided member 127 may be provided at least in a range in which it is in sliding contact with the guide surface (inner peripheral surface of the magnetic core 101) 101a (hereinafter, referred to as a sliding contact range).

That is, in the fuel injection device 100 of this embodiment, a valve body 117 for opening and closing the flow path is provided on one end side, and a guide provided on the other end side and formed on the inner peripheral portion 101a of the fixed core 101. It has a valve member 104 provided with a guided portion 127d that is slidably contacted with the portion to be guided. The valve member 104 is provided on the side opposite to the side of one end of the valve member 104 with respect to the guided portion 127d, and as it goes from the side of the guided portion 127d toward the side opposite to the side of one end of the valve member 104. It has a curved portion 127f that bends inward in the radial direction. The radius of curvature R127f of the curved portion 127f has a size of 40% or more with respect to the inner radius R101a of the guide portion 101a configured in the fixed core 101.

The surface pressure applied to the inner peripheral surface (guide portion) 101a of the magnetic core 101 will be described with reference to FIG. FIG. 6 shows an example of the calculation result of the surface pressure (Hertz surface pressure) related to the inner peripheral surface 101a when the guided portion 127d of the valve member 104 is pressed against the inner peripheral surface 101a of the magnetic core (fixed core) 101. It is a figure which shows.

The curved portion 127f of this embodiment is composed of a curved surface having a curvature at least in a range in which the guide portion (inner peripheral surface of the magnetic core 101) 101a is in sliding contact with the curved portion 127f. That is, the curved portion 127f is composed of a curved surface having a curvature. This curvature does not need to be set to a constant value, and the curvature of the curved portion 127f may change from the guided portion 127d side toward the upper surface 127a side. That is, the radius of curvature R127f of the curved portion 127f may change from the guided portion 127d side toward the upper surface 127a side.

However, the larger the radius of curvature R127f of the curved portion 127f, the smaller the surface pressure acting on the guide portion 101a, and the sliding resistance received by the curved portion 127f and the wear generated on the guide portion 101a can be reduced. Therefore, in this embodiment, the radius of curvature R127f of the curved portion 127f is set to a size of 40% or more with respect to the inner radius R101a of the guide portion 101a configured in the fixed core 101.

In FIG. 6, when the ratio (R127f / R101a) of the radius of curvature R127f of the curved portion 127f to the inner radius R101a of the guide portion 101a becomes 40% or more, the reduction rate of the Hertz surface pressure Po becomes substantially constant and the Hertz surface pressure Po Is a small value. In other words, when R127f / R101a is 40% or less, the Hertz surface pressure Po increases sharply as R127f / R101a becomes smaller. Therefore, R127f / R101a of this embodiment is set to a size of 40% or more.

When R127f / R101a becomes 60% or more, the change in the reduction rate of the Hertz surface pressure Po becomes more constant. Therefore, it is preferable that R127f / R101a is set to a size of 60% or more.

When the fixed core 101 is made of a soft magnetic material, the guide portion 101a of the fixed core 101 preferably has a surface pressure resistance of about 320 to 330 MPa in consideration of wear resistance and the like. From FIG. 6, it can be seen that the surface pressure resistance of the guide portion 101a can be set to a sufficiently large value by setting R127f / R101a of the guide portion 101a to 85% or more. That is, by setting R127f / R101a of the guide portion 101a to 85% or more, the surface pressure generated in the guide portion 101a of the fixed core 101 becomes smaller than the surface pressure resistance of the fixed core 101. As a result, it is possible to highly suppress the occurrence of wear due to the curved portion 127f sliding in contact with the guide portion 101a of the fixed core 101.

Further, since the diameter of the guided member 127 is smaller than the diameter of the inner peripheral surface 101a of the magnetic core 101, by setting R127f / R101a to a size of 40% or more, the curved portion with respect to the radius of the guided member 127. The ratio of the radius of curvature R127f of 127f is a value larger than 40%. Therefore, the radius of curvature R127f of the curved portion 127f of the present embodiment has a large radius of curvature as compared with general chamfering by setting R127f / R101a to a size of 40% or more.

Note that R127f / R101a can be set to a value larger than 100%. However, since the axial length of the guided member 127 is structurally limited, the axial length of the curved portion 127f is also limited. Within this limitation, the radius of curvature R127f of the curved portion 127f is such that when the valve member 104 is tilted with respect to the central axis of the inner peripheral surface 101a of the magnetic core 101, the curved portion 127f is formed on the guide portion 101a of the fixed core 101. Is limited to the size that can be slid.

Return to FIG. 5 for explanation. The upper surface 127a of the guided member 127 constitutes a spring receiving portion (spring seat) of the first spring 118. In this embodiment, the outer diameter of the upper surface 127a of the guided member 127 is φ127a, the outer diameter of the first spring 118 is φ118A, the inner diameter of the first spring 118 is φ118B, and the average diameter of the first spring 118 (spring average diameter). When φ118C is used, φ127a, φ118A and φ118C have a relationship of φ118C <φ127a <φ118A. This is so that the upper start point of the curved portion 127f connected to the spring receiving portion (upper surface of the guided member 127) 127a is located between the average diameter φ118C of the first spring 118 and the outer diameter φ118A of the first spring 118. Means to be formed. Note that φ118C is an intermediate value between φ118A and φ118B ((φ118A + φ118B) / 2).

This action and effect will be described with reference to FIG. FIG. 7 is a conceptual diagram illustrating a fuel flow in the vicinity of the first spring 118 and the guided member (rod head) 127.

In FIG. 7, (A) shows the guided member 127'when the chamfered portion 127 g is provided on the upstream side of the guided portion 127d, and (B) shows the curved portion 127f on the upstream side of the guided portion 127d. The guided member 127 of this embodiment provided is shown. In (A), the fuel flow FLa flowing through the notch surface 127e flows to the downstream side of the guided member 127, but the flow of the fuel flow FLb toward the portion formed by the guided portion 127d is stopped by the guided portion 127d. ..

On the other hand, in the case of (B), since the curved portion 127f is provided so as to have a relationship of φ127a <φ118A, the fuel flow FLb toward the portion where the guided portion 127d is formed is cut off via the curved portion 127f. It can flow to the notch surface 127e and to the downstream side of the guided member 127. Therefore, the pressure loss in the fuel flow can be reduced, the operating limit fuel pressure can be improved, and the minimum fuel injection amount can be reduced.

Return to FIG. 5 for explanation. In this embodiment, the valve member 104 is a regulating portion (spring guide portion) that regulates the radial operation of the first spring 118 on the side opposite to the side of one end portion where the valve body 117 is provided with respect to the spring receiving portion 127a. ) 127h is provided. As a result, it is possible to suppress the positional deviation between the valve axis of the valve member 104 and the central axis of the first spring 118 that urges the valve member 104 in the downward direction (valve closing direction), and the curved portion 127f serves as a guide portion. The surface pressure applied to the guide portion 101a at the time of sliding contact with the 101a can be reduced. As a result, it is possible to suppress the occurrence of wear due to the curved portion 127f sliding in contact with the guide portion 101a.

Further, in the present embodiment, the curved portion 127f is formed so that the axial length L127f is larger than the axial length L127d of the guided portion 127d. That is, the fuel injection device 100 of the present embodiment is provided with a valve body 117 for opening and closing the flow path on one end side, is provided on the other end side, and is configured on the inner peripheral portion 101a of the fixed core 101. It has a valve member 104 provided with a guided portion 127d that is slidably contacted with and guided by the guide portion. The valve member 104 is provided on the side opposite to the side of one end of the valve member 104 with respect to the guided portion 127d, and as it goes from the side of the guided portion 127d toward the side opposite to the side of one end of the valve member 104. It has a curved portion 127f that bends inward in the radial direction. The curved portion 127f is formed so that the axial length L127f is larger than the axial length L127d of the guided portion 127d.

As a result, the fuel flow FLb described with reference to FIG. 7 can easily flow to the notch surface 127e via the curved portion 127f. Therefore, the pressure loss in the fuel flow can be reduced, the operating limit fuel pressure can be improved, and the minimum fuel injection amount can be reduced.

The present invention is not limited to the above embodiment, and various modifications and other configurations can be combined within a range that does not deviate from the gist thereof. Further, the present invention is not limited to the one including all the configurations described in the above-described embodiment, and includes the one in which a part of the configurations is deleted.

100 ... Fuel injection device, 101 ... Fixed core (magnetic core), 101a ... Inner peripheral portion (guide portion) of fixed

core

101, 104 ... Valve member, 117 ... Valve body, 118 ... Spring member (first spring), 127a ... Spring member (first spring) 118 spring receiving portion (upper surface of guided member 127) 127d ... Guided portion 127f ... Curved portion 127h ... Restricting portion (spring guide portion), R101a ... Radius, R127f ... Curvature radius of curved portion 127f, φ118A ... Outer diameter of first spring 118, φ118B ... Inner diameter of first spring 118, φ118C ... Average diameter of first spring 118, φ127a ... Upper surface of guided member 127 (spring) Receiving part) Outer diameter of 127a.

Claims

A valve body for opening and closing the flow path is provided on one end side, and a guided portion provided on the other end side and guided by sliding contact with a guide portion formed on the inner peripheral portion of the fixed core is provided. A fuel injection device having a valve member
It is provided on the side opposite to the side of one end of the valve member with respect to the guided portion, and bends inward in the radial direction from the side of the guided portion toward the side opposite to the side of one end of the valve member. Has a curved part,
A fuel injection device having a radius of curvature of 40% or more with respect to the inner radius of the guide portion of the fixed core.
In the fuel injection device according to claim 1,
The valve member has a spring receiving portion of the spring member that urges the valve member in the valve closing direction at the other end.
The curved portion is a fuel injection device provided between the spring receiving portion and the guided portion in the axial direction.
In the fuel injection device according to claim 2.
The curved portion is a fuel injection device in which an upper edge portion on the side of the spring receiving portion is connected to a spring receiving surface constituting the spring receiving portion.
In the fuel injection device according to claim 2.
The curved portion is a fuel injection device in which a lower edge portion on the side of the guided portion is connected to the guided portion.
In the fuel injection device according to claim 2.
In the curved portion, the upper edge portion on the side of the spring receiving portion is connected to the spring receiving surface constituting the spring receiving portion, and the lower edge portion on the side of the guided portion is connected to the guided portion. Fuel injection device.
In the fuel injection device according to claim 3,
The outer diameter of the spring receiving surface is φ127a, the outer diameter of the spring member is φ118A, the inner diameter of the spring member is φ118B, and the spring member is an intermediate value between the outer diameter φ118A of the spring member and the inner diameter φ118B of the spring member. When the average diameter of φ118C is φ118C, φ127a, φ118A and φ118C are fuel injection devices having a relationship of φ118C <φ127a <φ118A.
In the fuel injection device according to claim 2.
The valve member is a fuel injection device including a regulating portion that regulates the radial operation of the spring member on a side opposite to the side of one end portion where the valve body is provided with respect to the spring receiving portion.
In the fuel injection device according to claim 5.
The curved portion is a fuel injection device formed so that the axial length is larger than the axial length of the guided portion.
A valve body for opening and closing the flow path is provided on one end side, and a guided portion provided on the other end side and guided by sliding contact with a guide portion formed on the inner peripheral portion of the fixed core is provided. A fuel injection device having a valve member
It is provided on the side opposite to the side of one end of the valve member with respect to the guided portion, and bends inward in the radial direction from the side of the guided portion toward the side opposite to the side of one end of the valve member. Has a curved part,
The curved portion is a fuel injection device formed so that the axial length is larger than the axial length of the guided portion.