JP5509901B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve for an internal combustion engine.

  2. Description of the Related Art Conventionally, a fuel injection valve in which fuel injection from an injection hole to an internal combustion engine is intermittently performed by reciprocating movement of a valve member in a state of being pressed against a support surface of the internal combustion engine by the pressure of fuel supplied from a fuel pipe has been widely used. Yes. For example, in the fuel injection valves disclosed in Patent Documents 1 and 2, the electromagnetic coil disposed on the outer peripheral side of the valve housing that accommodates the valve member is covered from the outer peripheral side by a coil housing supported on the support surface of the internal combustion engine, and the electromagnetic coil By generating a magnetic force by energizing the valve member, the valve member is accurately driven.

  In the fuel injection valves disclosed in Patent Documents 1 and 2, the valve housing is press-fitted into the coil housing, and the housings are welded to each other at the press-fitting location. According to this configuration, when the valve member is driven in response to energization of the electromagnetic coil, a magnetic circuit for generating the driving magnetic force is formed through each housing.

JP 2006-90278 A JP 2009-243466 A

  However, in the fuel injection valve disclosed in Patent Document 1, since the valve housing of the coil housing is press-fitted on the inner peripheral side and welded to the cylindrical portion forming the magnetic circuit, the cylindrical portion is deformed by welding heat. There is a risk of changing the magnetic flux density of the magnetic circuit due to welding variations. Such a change in magnetic flux density is undesirable because it varies the drive characteristics of the valve member due to the magnetic force.

  Furthermore, in the fuel injection valve of Patent Document 1, the cylindrical valve housing in which the pressing axial force acts on the support surface side due to the pressure of the fuel supplied from the fuel pipe is compared with the coil housing supported by the support surface The inner peripheral surface to be press-welded is only supported in the radial direction. Therefore, shear stress is generated at the weld interface between the valve housing and the coil housing, and there is a risk of causing fatigue failure of the weld interface. Such fatigue failure at the weld interface is undesirable because it reduces durability.

  On the other hand, in the fuel injection valve of Patent Document 2, the coil housing is provided with a portion that protrudes inward from the cylindrical portion to which the valve housing is press-welded and contacts the support surface, and the protrusion is opposite to the support surface. Engage with the valve housing on the side. According to such a configuration, the valve housing is supported by the protruding portion on the support surface side of the coil housing, so that the pressing axial force acting on the valve housing toward the support surface side can be received by the protruding portion. Therefore, durability can be secured by suppressing the occurrence of fatigue failure due to shear stress at the weld interface between the valve housing and the coil housing.

  However, as a result of intensive studies by the present inventors, even in the fuel injection valve of Patent Document 2, the cylindrical portion of the coil housing that is press-fitted into the valve housing to form a magnetic circuit is welded during welding. Thus, it has been found that there is a risk of causing variation in the drive characteristics of the valve member. Hereinafter, this problem will be described.

  Schematic diagram 8 relating to the fuel injection valve of Patent Document 2 shows a case where a pressing force due to press-fitting strongly acts on a welded portion 1002a of the cylindrical portion 1002 of the coil housing 1000 with the valve housing 1100. In this case, in the tubular portion 1002 of the coil housing 1000, the portion 1002b where the magnetic circuit is formed on the electromagnetic coil 1200 side from the portion 1002a where the force is strongly applied is extended from the valve housing 1100 to the outer peripheral side in the radial direction. Thermal deformation such as separation tends to occur. Here, if the formation location 1002b of the magnetic circuit is separated from the valve housing 1100 in the radial direction and the air gap 1300 is generated, the magnetic flux density of the magnetic circuit is reduced, so that the drive characteristics of the valve member due to the magnetic force deviate from the design characteristics. It ends up.

  Moreover, the schematic diagram 9 regarding the fuel injection valve of Patent Document 2 shows a portion 1002b of the cylindrical portion 1002 of the coil housing 1000 that is located on the opposite side of the protruding portion 1004 of the housing 1000 with the welded portion 1002a interposed therebetween. It shows the case where the tension force due to press-fitting acts strongly. In this case, thermal deformation is unlikely to occur in the tubular portion 1002 at the portion 1002b where the force is strongly applied and the welded portion 1002a in close contact with the valve housing 1100. Therefore, in the valve housing 1100, on the opposite side of the welded portion 1002a with respect to the strong acting portion 1002b, thermal deformation is likely to occur such that the protruding portion 1004 is separated from the valve housing 1100 in the axial direction. Here, when the protruding portion 1004 is separated from the valve housing 1100 and the gap 1302 is generated, it becomes difficult to receive the pressing axial force acting on the valve housing 1100 by the protruding portion 1004. As a result, a shear stress is generated at the weld interface between the valve housing 1100 and the welded portion 1002a, so that the durability ensuring effect as described above cannot be obtained.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a fuel injection valve that obtains high durability as well as stable driving characteristics of a valve member.

According to the first aspect of the present invention, the fuel injection in which fuel injection from the nozzle hole to the internal combustion engine is intermittently performed by the reciprocating movement of the valve member in a state of being pressed against the support surface of the internal combustion engine by the pressure of the fuel supplied from the fuel pipe. A valve member that houses the valve member and is arranged on the outer peripheral side of the valve housing, and a cylindrical valve housing in which a pressing axial force acts toward the support surface side by the pressure of fuel supplied from the fuel pipe, In the fuel injection valve, comprising: an electromagnetic coil that generates a magnetic force for driving the coil by energization; and a coil housing that covers the electromagnetic coil from the outer peripheral side and is supported by the support surface. The valve housing is press-fitted into the inner periphery, and a magnetic circuit for generating a magnetic force in response to energization of the electromagnetic coil is formed with the valve housing, and the first cylindrical portion is supported with respect to the first cylindrical portion. A second cylindrical part sandwiched between a second cylindrical part adjacent to the surface side and welded to the valve housing through a radial gap formed between the inner peripheral side valve housing and the first cylindrical part. possess a protrusion that engages the valve housing protrudes into the inner peripheral side than the parts, the radial thickness of the portion where the second cylindrical portion is welded through the radial clearance in the valve housing, in a valve housing It is characterized by being thicker than the thickness in the radial direction of the portion where the first cylindrical portion is press-fitted .

  As described above, according to the first aspect of the present invention, the electromagnetic coil disposed on the outer peripheral side of the valve housing is covered from the outer peripheral side, and the inner side of the first cylindrical portion of the coil housing supported by the support surface of the internal combustion engine. On the circumferential side, the valve housing is press-fitted on the support surface side of the electromagnetic coil. With this configuration, the magnetic circuit for generating the driving magnetic force of the valve member accommodated in the valve housing in response to the energization of the electromagnetic coil is formed through the first tubular portion and the press-fitted portion of the valve housing. The Rukoto.

  However, in the coil housing according to the first aspect of the present invention, the second cylindrical portion adjacent to the support surface side with respect to the first cylindrical portion forms a radial gap formed between the inner peripheral side valve housing. And welded to the valve housing. According to this configuration, the magnetic circuit formed by the first cylindrical portion together with the press-fitting portion of the valve housing is such that the second cylindrical portion separated from the electromagnetic coil to the support surface side than the first cylindrical portion is welded to the valve housing. It becomes difficult to be affected by welding variations from the weld interface formed between the two parts. In addition, even if the second cylindrical portion is welded to the valve housing in a state where the pressing force due to the press-fitting of the valve housing is applied to the first cylindrical portion, the deformation due to the welding heat is caused by the radial clearance between the valve housing and the valve housing. Therefore, it becomes easy to concentrate on the second cylindrical portion in which the action of the tightening force is reduced. According to this, since the deformation of the coil housing that reduces the magnetic flux density of the magnetic circuit by separating the first tubular portion from the valve housing is suppressed, it is possible to stabilize the drive characteristics of the valve member due to the magnetic force. It becomes.

According to the first aspect of the present invention, the protruding portion that protrudes toward the inner peripheral side of the second cylindrical portion welded to the valve housing in the coil housing is engaged with the valve housing. In such a configuration, it means that the valve housing is supported in the axial direction by the unit out collision, pressing axial force acting towards the supporting surface in the cylindrical valve housing may be received by the protrusion. Moreover, even if the second cylindrical portion is welded to the valve housing in a state where the pressing force due to the press-fitting is applied to the first cylindrical portion, the protruding portion is sandwiched between the first cylindrical portion and the second cylindrical portion. If the thermal deformation is concentrated as described above, the deformation that separates the protrusion from the valve housing is suppressed. Accordingly, it is possible to suppress the occurrence of fatigue failure due to shear stress at the weld interface between the valve housing and the second cylindrical portion, and to improve durability.

  According to the second aspect of the present invention, the valve housing has the reduced diameter portion that is reduced in diameter toward the support surface side, and the flange-like protrusion is engaged with the reduced diameter portion. According to this, the protrusion part which protrudes in the shape of a bowl to the inner peripheral side of the coil housing is engaged with the reduced diameter part of the valve housing which is reduced in diameter toward the support surface side, so that the valve It is possible to reliably receive the pressing axial force acting on the housing toward the support surface. Therefore, in combination with the concentrated action of thermal deformation on the second cylindrical portion, the occurrence of fatigue failure due to shear stress can be suppressed at the weld interface between the housing and the second cylindrical portion, so that high durability is achieved. It becomes possible to acquire.

  According to invention of Claim 3, the radial direction thickness of a 2nd cylindrical part is thinner than the radial direction thickness of a 1st cylindrical part. According to this, even when the second cylindrical portion is welded to the valve housing in a state where the pressing force due to press-fitting is applied to the first cylindrical portion, the action of the pressing force is reduced by the radial gap and the first cylindrical portion is welded. Thermal deformation can be reliably concentrated on the second cylindrical portion formed thinner in the radial direction than the cylindrical portion. Therefore, the coil housing is prevented from being deformed by causing the first cylindrical portion to be separated from the valve housing and causing a decrease in the magnetic flux density of the magnetic circuit, or by causing the protrusion to be separated from the valve housing and causing fatigue failure of the weld interface. Thus, it is possible to obtain a stable driving characteristic and high durability of the valve member.

  According to invention of Claim 4, the radial direction thickness of a 2nd cylindrical part is thinner than the radial direction thickness of the location where a 2nd cylindrical part is welded in a valve housing. According to this, even if the second cylindrical portion is welded to the valve housing in a state where the pressing force due to the press-fitting is applied to the first cylindrical portion, the action of the pressing force is reduced by the radial gap and the valve housing Thermal deformation can be reliably concentrated on the second cylindrical portion formed to be thinner in the radial direction than the welded portion. Therefore, the coil housing is prevented from being deformed by causing the first cylindrical portion to be separated from the valve housing and causing a decrease in the magnetic flux density of the magnetic circuit, or by causing the protrusion to be separated from the valve housing and causing fatigue failure of the weld interface. Thus, it is possible to achieve stable driving characteristics and high durability of the valve member. At the same time, it is possible to avoid the situation in which the valve member housed in the valve housing is hindered from being driven by deformation of the valve housing, and to stabilize the drive characteristics of the valve member.

  According to the invention described in claim 5, the radial gap between the second cylindrical portion and the valve housing is formed at an interval of half or less with respect to the radial thickness of the second cylindrical portion. As a result, the second cylindrical portion passes through the radial gap having a distance of half or less of the radial thickness of the second cylindrical portion, thereby concentrating the thermal deformation on the second cylindrical portion. It can be reliably welded to the valve housing without hindering. Therefore, the coil housing is prevented from being deformed by causing the first cylindrical portion to be separated from the valve housing and causing a decrease in the magnetic flux density of the magnetic circuit, or by causing the protrusion to be separated from the valve housing and causing fatigue failure of the weld interface. Thus, it is possible to obtain a stable driving characteristic and high durability of the valve member.

  According to the invention described in claim 6, the second cylindrical portion has a concave portion that is recessed toward the outer peripheral side with respect to the inner peripheral surface of the first cylindrical portion, and the outer peripheral surface of the valve housing that closes the opening of the concave portion, A radial gap is formed between the recess. As a result, the radial gap can be formed by closing the concave portion recessed toward the outer peripheral side of the first cylindrical portion with the outer peripheral surface of the valve housing in the second cylindrical portion. It is easy to ensure surface accuracy for the outer peripheral surface of the valve housing which is also the press-fitting surface. Accordingly, the deformation of the coil housing caused by the surface roughness of the outer peripheral surface of the valve housing and the first cylindrical portion being separated from the outer peripheral surface and causing a decrease in the magnetic flux density of the magnetic circuit is suppressed by the coil housing, and the valve member It becomes possible to stabilize the drive characteristics.

  According to the seventh aspect of the present invention, the valve housing has a concave portion that is recessed from the outer peripheral surface of the valve housing to the inner peripheral side, the inner peripheral surface of the second cylindrical portion that closes the opening of the concave portion, the concave portion, A radial gap is formed between the two. As a result, the radial gap can be formed by closing the concave portion recessed from the outer peripheral surface of the valve housing to the inner peripheral side with the inner peripheral surface of the second cylindrical portion, so that the concave portion is formed by processing the outer peripheral surface of the valve housing. It is possible to improve the productivity by facilitating the work to be performed.

It is sectional drawing which shows the fuel injection valve by 1st embodiment of this invention. It is sectional drawing which expands and shows the principal part of the fuel injection valve by 1st embodiment of this invention. It is a schematic diagram for demonstrating the characteristic of the fuel injection valve by 1st embodiment of this invention. It is a schematic diagram for demonstrating the effect of the fuel injection valve by 1st embodiment of this invention. It is a schematic diagram for demonstrating the effect of the fuel injection valve by 1st embodiment of this invention. It is sectional drawing which expands and shows the principal part of the fuel injection valve by 2nd embodiment of this invention. It is a schematic diagram for demonstrating the characteristic of the fuel injection valve by 1st embodiment of this invention. It is a schematic diagram for demonstrating the subject solved by this invention. It is a schematic diagram for demonstrating the subject solved by this invention.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In addition, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol to the corresponding component in each embodiment.

(First embodiment)
FIG. 1 shows a fuel injection valve 10 according to a first embodiment of the present invention. The fuel injection valve 10 is attached between the internal combustion engine 1 and the fuel pipe 2 and injects fuel supplied from the fuel pipe 2 into the cylinder chamber 1 a of the internal combustion engine 1. In this embodiment, the fuel injection valve 10 injects fuel into the cylinder chamber 1a of the gasoline internal combustion engine 1. For example, the fuel injection valve 10 injects fuel into an intake passage communicating with the cylinder chamber 1a of the gasoline internal combustion engine 1. Or what injects a fuel into the cylinder chamber 1a of the diesel internal combustion engine 1 etc. may be sufficient.

(Constitution)
First, the structure of the fuel injection valve 10 by 1st embodiment is demonstrated based on FIG. The fuel injection valve 10 includes a valve housing 11, a fixed core 20, a movable core 30, a valve member 40, elastic members 50 and 52, and a drive unit 60.

  The valve housing 11 includes a pipe member 12, an inlet member 13, a nozzle member 14, and the like. The pipe member 12 is formed in a cylindrical shape, and the first magnetic part 120, the nonmagnetic part 121, and the second magnetic part 122 are sequentially arranged in the axial direction from the cylinder head 1b side to the fuel pipe 2 side of the internal combustion engine 1. Have. The magnetic portions 120 and 122 made of a magnetic material and the nonmagnetic portion 121 made of a nonmagnetic material are coupled by, for example, laser welding. With such a coupling structure, the nonmagnetic portion 121 prevents the magnetic flux from being short-circuited between the first magnetic portion 120 and the second magnetic portion 122.

  A cylindrical inlet member 13 is fixed to the axial end of the second magnetic portion 122 opposite to the nonmagnetic portion 121. The inlet member 13 has a fuel inlet 15 formed on the inner peripheral side so that fuel supplied from a fuel pump (not shown) through the fuel pipe 2 flows. In this embodiment, a fuel filter 16 is accommodated on the inner peripheral side of the inlet member 13 in order to filter the fuel supplied to the fuel inlet 15.

  The nozzle member 14 is fixed to an axial end of the first magnetic part 120 opposite to the nonmagnetic part 121. The nozzle member 14 is formed in a bottomed cylindrical shape, and a fuel passage 17 through which fuel flows is formed in cooperation with the pipe member 12. The nozzle member 14 is inserted into the mounting hole 1c of the cylinder head 1b together with the first magnetic portion 120 of the pipe member 12 of the valve housing 11. The nozzle member 14 is provided with a nozzle hole 18 and a valve seat 19. A plurality of nozzle holes 18 communicating with the fuel passage 17 are provided at equal intervals around the central axis of the nozzle member 14 and are each formed in a cylindrical hole shape. The valve seat 19 is formed around the fuel passage 17 on the fuel upstream side of each nozzle hole 18.

  The fixed core 20 is formed in a cylindrical shape from a magnetic material, and is coaxially fixed to the inner peripheral surfaces of the nonmagnetic portion 121 and the second magnetic portion 122 in the pipe member 12 of the valve housing 11. The fixed core 20 is formed with a through hole 21 penetrating in the axial direction in a cylindrical hole shape in the central portion in the radial direction. The through hole 21 communicates with the fuel inlet 15 of the inlet member 13, and the supplied fuel flows into the inlet 15. A first elastic member 50 is accommodated in the inner peripheral side of the through hole 21 so as to be elastically deformable, and an adjusting pipe 22 for adjusting a set load of the elastic member 50 is fixed by press-fitting.

  The movable core 30 is formed of a magnetic material in a cylindrical shape, is coaxially accommodated on the inner peripheral side of the pipe member 12 of the valve housing 11, and has one axial end face 32 opposed to the fixed core 20. The movable core 30 is slidably guided on both sides in the axial direction by the nonmagnetic portion 121 of the pipe member 12 of the valve housing 11. Thereby, the axial end surface 32 of the movable core 30 can contact | abut to the said core 20 by the axial direction movement to the fixed core 20 side.

  The movable core 30 is formed with an axial hole 34 penetrating in the axial direction in the shape of a cylindrical hole in the central portion in the radial direction. In such a movable core 30, the axial hole 34 is open to an axial end face 32 on the fixed core 20 side and an axial end face 33 on the opposite side to the fixed core 20.

  The valve member 40 is formed of a nonmagnetic material into a needle shape having a circular cross section, and is accommodated coaxially on the inner peripheral side of the pipe member 12 and the nozzle member 14 of the valve housing 11. The valve member 40 has a seat portion 41 that faces the valve seat 19 of the nozzle member 14 at the end in the axial direction on the nozzle member 14 side. The valve member 40 opens each nozzle hole 18 with respect to the fuel passage 17 by moving the seat portion 41 away from the valve seat 19 by moving in the axial direction toward the fixed core 20. On the other hand, the valve member 40 closes each injection hole 18 with respect to the fuel passage 17 by seating the seat portion 41 on the valve seat 19 by moving in the axial direction opposite to the fixed core 20. Thus, the valve member 40 can intermittently inject fuel from the nozzle holes 18 to the cylinder chamber 1a by opening and closing each nozzle hole 18 by reciprocating movement in both axial directions.

  The valve member 40 has a columnar shaft portion 42 extending in the axial direction from the seat portion 41 toward the fixed core 20 side as a main body portion of the member 40. The shaft portion 42 is coaxially inserted into the axial hole 34 of the movable core 30 and is slidable on both sides in the axial direction with respect to the inner peripheral surface of the hole 34.

  The valve member 40 has a circular hook-shaped protrusion 44 protruding from the shaft portion 42 toward the outer peripheral side at an axial end portion on the fixed core 20 side. The protrusion 44 formed with a smaller diameter than the through hole 21 of the fixed core 20 is inserted into the hole 21 and is in contact with the first elastic member 50. Further, the protrusion 44 formed with a larger diameter than the axial hole 34 of the movable core 30 can come into contact with the axial end surface 32 of the core 30 from the fixed core 20 side.

  The valve member 40 has a fuel hole 46 across the shaft portion 42 and the protrusion 44. The fuel hole 46 is open to the contact surface of the protrusion 44 with the first elastic member 50 and the outer peripheral surface of the shaft portion 42 exposed from the axial hole 34. The fuel hole 46 communicates between the through hole 21 into which the protrusion 44 is inserted and the fuel passage 17 by such an opening form. Therefore, the fuel that has flowed into the through hole 21 from the fuel inlet 15 reaches the fuel passage 17 via the fuel hole 46.

  The first elastic member 50 is made of a metal compression coil spring and is coaxially accommodated on the inner peripheral side of the through hole 21 of the fixed core 20. One end of the first elastic member 50 is locked to the adjusting pipe 22, and the other end of the elastic member 50 is locked to the protrusion 44 of the valve member 40. With such a locking structure, the first elastic member 50 is compressed between the adjusting pipe 22 and the valve member 40 to be elastically deformed, thereby restoring force that biases the valve member 40 to the side opposite to the fixed core 20. Is generated.

  The second elastic member 52 is made of a metal compression coil spring, and is accommodated coaxially on the inner peripheral side of the first magnetic portion 120 of the pipe member 12 of the valve housing 11 and on the outer peripheral side of the shaft portion 42 of the valve member 40. Has been. One end portion of the second elastic member 52 is locked to the first magnetic portion 120, and the other end portion of the elastic member 52 is locked to the axial hole 34 of the movable core 30. With this locking structure, the second elastic member 52 is compressed between the valve housing 11 and the movable core 30 and elastically deformed, thereby restoring the restoring force that urges the movable core 30 toward the fixed core 20 side. It occurs smaller than the restoring force of the member 50.

  The drive unit 60 includes an electromagnetic coil 61, a resin bobbin 62, a connector 64, a coil housing 66, and the like. The electromagnetic coil 61 is formed by winding a metal wire around a resin bobbin 62. The electromagnetic coil 61 is coaxially disposed on the outer peripheral side of the nonmagnetic portion 121 and the second magnetic portion 122 on the outer peripheral side of the fixed core 20 in the pipe member 12 of the valve housing 11. The connector 64 has a terminal 64 a that electrically connects an external control circuit (not shown) and the electromagnetic coil 61, and energization of the electromagnetic coil 61 is controlled by the control circuit. .

  The coil housing 66 is formed in a cylindrical shape by a magnetic material, and is disposed on the outer peripheral side of the electromagnetic coil 61 and the valve housing 11 to cover the coil 61. At the same time, the coil housing 66 is supported in the axial direction in a pressed state against a stepped support surface 1d formed in the mounting hole 1c of the internal combustion engine 1 so as to expand to the fuel pipe 2 side. . Here, in particular, in the present embodiment, the inlet member 13 of the valve housing 11 is moved to the axial nozzle member 14 side, which is the support surface 1d side, by the pressure of fuel supplied from the fuel pipe 2 to the fuel inlet 15. A pressing axial force N is applied. Therefore, the fuel injection valve 10 according to the present embodiment intermittently injects fuel from each injection hole 18 under the state where the coil housing 66 is pressed against the support surface 1d by the action of the pressing axial force N.

  Here, when the electromagnetic coil 61 is excited by energization, the magnetic circuit C formed by the coil housing 66, the first magnetic part 120, the movable core 30, the fixed core 20, and the second magnetic part 122 is formed together (see FIG. 3). In addition, magnetic flux flows. As a result, a magnetic attractive force is generated between the movable core 30 and the fixed core 20 facing each other as a “magnetic force” that attracts and drives the movable core 30 toward the fixed core 20. On the other hand, when the electromagnetic coil 61 is demagnetized by stopping energization, the magnetic flux does not flow in the magnetic circuit C, so that the magnetic attractive force disappears between the movable core 30 and the fixed core 20.

  In the valve opening operation of the fuel injection valve 10 configured as described above, a magnetic attractive force acts on the movable core 30 in response to the start of energization of the electromagnetic coil 61. Due to the action of the magnetic attraction force, the movable core 30 receives the restoring force of the first elastic member 50, and the valve member 40 in which the protrusion 44 is in contact with the axial end surface 32 on the fixed core 20 side is used as the restoring force. Press against. As a result, the movable core 30 moves together with the valve member 40 toward the core 20 until the axial end surface 32 collides with the fixed core 20, so that the seat portion 41 moves away from the valve seat 19 and moves to the core 20 side. Fuel is injected from the nozzle hole 18.

  Further, in the valve closing operation of the fuel injection valve 10 after the valve opening operation, the magnetic attractive force acting on the movable core 30 disappears in response to the stop of energization of the electromagnetic coil 61. Due to the disappearance of the magnetic attractive force, the valve member 40 that receives a restoring force larger than that of the second elastic member 52 from the first elastic member 50 causes the projecting portion 44 to abut against the axial end surface 32 to fix the movable core 30 to the fixed core. 20 is pressed to the opposite side. As a result, since the seat portion 41 is seated on the valve seat 19, the movement of the valve member 40 is stopped, and the fuel injection from each nozzle hole 18 is also stopped.

(Feature)
Next, features of the fuel injection valve 10 according to the first embodiment will be described in detail. As shown in FIGS. 1 and 2, the first magnetic part 120 of the pipe member 12 of the valve housing 11 is reduced in diameter so as to reduce in diameter toward the nozzle member 14 in the axial direction that is the support surface 1 d side. 120a is formed. The reduced diameter portion 120 a is supported by the support surface 1 d via the coil housing 66. Here, in particular, the reduced diameter portion 120a of the present embodiment is formed in a stepped surface shape that gradually decreases in diameter, but may be formed in a tapered surface shape that gradually decreases in diameter, for example.

  The coil housing 66 has a coil housing portion 660, a first tubular portion 662, a second tubular portion 664, and a protruding portion 666 in order in the axial direction toward the nozzle member 14 as shown in FIG. Specifically, the bottomed cylindrical coil housing portion 660 covers and accommodates the electromagnetic coil 61 from the outer peripheral side in the radial direction.

  The cylindrical first tubular portion 662 is located closer to the support surface 1d than the electromagnetic coil 61 by being adjacent to the coil support portion 660 on the support surface 1d side in the axial direction. An inner peripheral surface 662a of the first cylindrical portion 662 is located at a portion 120b of the pipe member 12 of the valve housing 11 on the side opposite to the support surface 1d across the reduced diameter portion 120a. It is press-fitted into the outer peripheral surface 120c. As a result, the first cylindrical portion 662 responds to energization of the electromagnetic coil 61 with a magnetic circuit C for generating a magnetic attractive force that drives the valve member 40 as schematically shown in FIG. It forms with the 1st magnetic part 120.

  As shown in FIG. 2, the cylindrical second cylindrical portion 664 is adjacent to the first cylindrical portion 662 on the side of the support surface 1d in the axial direction, so that the electromagnetic coil 61 and the first cylindrical portion 662 are adjacent to each other. Is also located away from the support surface 1d. The second tubular portion 664 is provided with a recessed portion 665 so as to be recessed toward the outer peripheral side in the radial direction with respect to the inner peripheral surface 662a of the first tubular portion 662. In the present embodiment, the recess 665 is formed in an annular groove shape so as to extend over the entire region in the circumferential direction and the axial direction. Thereby, as shown in FIG. 3, the radial thickness T2 of the second cylindrical portion 664 is set to be thinner than the minimum radial thickness T1 of the first cylindrical portion 662.

  As shown in FIG. 2, the first magnetic part 120 located on the radially inner side of the pipe member 12 of the valve housing 11 with respect to the second cylindrical part 664 is press-fitted into the first cylindrical part 662. The outer peripheral surface 120c having a substantially constant diameter is provided from the location 120b to the reduced diameter portion 120a. Thereby, a diameter having a width that can be appropriately set to, for example, several tens of μm between the outer peripheral surface 120c of the first magnetic part 120 that closes the opening 665a of the concave part 665 of the second cylindrical part 664 and the concave part 665. The direction gap Gr is formed continuously in the circumferential direction. And the 2nd cylindrical part 664 is welded to the inner peripheral side 1st magnetic part 120 in the whole area of the circumferential direction through this radial direction clearance gap Gr.

  Here, as shown in FIG. 3, the interval Δr of the radial gap Gr is set to be equal to or less than half of the radial thickness T2 of the second cylindrical portion 664 described above. As a result, even if welding to the first magnetic part 120 is performed from the outer peripheral side of the second cylindrical part 664 through the radial gap Gr, the melt of the second cylindrical part 664 that is thicker than the interval Δr of the gap Gr is removed. Since the single magnetic part 120 can be reliably brought into contact with, it is possible to avoid poor welding at the welding interface W. In addition, for the portion 120d where the second cylindrical portion 664 is welded in the first magnetic portion 120, the minimum radial thickness Tvh is set to be thicker than the radial thickness T2 of the second cylindrical portion 664. Therefore, rigidity is ensured.

  Now, as shown in FIG. 2, the circular hook-shaped protruding portion 666 is located more radially than the second cylindrical portion 664 from a position adjacent to the second cylindrical portion 664 on the support surface 1d side in the axial direction. Projects to the inner periphery. Thus, the protruding portion 666 is positioned with the second cylindrical portion 664 sandwiched between it and the first cylindrical portion 662, and is interposed between the reduced diameter portion 120a of the first magnetic portion 120 and the support surface 1d. ing. The protruding portion 666 is supported on the entire support surface 1d by bringing the axial end surface 666a opposite to the first cylindrical portion 662 into contact with the support surface 1d. At the same time, the protruding portion 666 is engaged with the reduced diameter portion 120a on the entire circumference by bringing the axial end surface 666b opposite to the support surface 1d into contact with the reduced diameter portion 120a of the first magnetic portion 120. Yes.

  In the first embodiment having such a characteristic configuration, when the coil housing 66 is fixed to the pipe member 12 of the valve housing 11, first, the first magnetic portion 120 of the pipe member 12 is coiled from the coil housing portion 660 side. It press-fits into the inner peripheral side of the first tubular portion 662 of the housing 66. With this press fitting, the projecting portion 666 of the coil housing 66 is engaged with the reduced diameter portion 120 a of the first magnetic portion 120, and then the second cylindrical portion 664 of the coil housing 66 is moved into the tube of the first magnetic portion 120. It welds to the inner peripheral side location 120d of the shape part 664 via the radial direction gap Gr.

  Here, for example, in the present embodiment, laser light is irradiated in the radial direction from the outer peripheral side of the second cylindrical portion 664, and the second cylindrical portion 664 is melted by the light energy. At this time, the melt of the second cylindrical portion 664 comes into contact with the inner peripheral side portion 120d of the first magnetic portion 120 through the radial gap Gr and melts the portion 120d, so that welding is completed by subsequent cooling and solidification. Will do. For example, when the first magnetic part 120 and the coil housing 66 made of stainless steel as a magnetic material are welded through the radial gap Gr, a welding method using a YAG laser or the like is employed.

  In the welding according to the present embodiment, the second cylindrical portion in which the action of the pressing force is reduced by the radial gap Gr in a state where the pressing force due to the press-fitting of the first magnetic portion 120 is applied to the first cylindrical portion 662. It is performed between 664 and the first magnetic part 120. As a result, as shown in FIGS. 4 and 5, the thermal deformation of the coil housing 66 not only reduces the action of the tightening force, but also more than the welded portion 120 d of the first cylindrical portion 662 and the first magnetic portion 120. It becomes easy to concentrate on the thin second tubular portion 664. In other words, according to the low-rigidity second tubular portion 664 that is released from the press-fitting of the first magnetic portion 120, it is possible to absorb distortion due to welding heat. Here, FIG. 4 shows an example of the case where the second cylindrical portion 664 is thermally deformed toward the radial gap Gr on the inner peripheral side, and FIG. 5 shows the second cylindrical portion 664 and the radial gap Gr. Shows an example in the case of thermal deformation toward the opposite outer peripheral side.

  4 and 5, in the first cylindrical portion 662 on the working side of the tightening force and the press-fitted portion 120b of the first magnetic portion 120, heat that separates the peripheral surfaces 662a and 120c from each other. Since the deformation can be suppressed, the adhesion of the peripheral surfaces 662a and 120c can be maintained. Therefore, it is possible to avoid a decrease in the magnetic flux density of the magnetic circuit C due to the separation between the peripheral surfaces 662a and 120c, and to realize a stable driving characteristic of the valve member 40 by the magnetic attractive force generated by the circuit C. Become.

  Further, in the coil housing 66 having the protruding portion 666 with the second cylindrical portion 664 sandwiched between the first cylindrical portion 662 on which the tightening force acts, the first cylindrical portion 662 has the first cylindrical portion 664 so that the first cylindrical portion 664 has a heat deformation concentration on the second cylindrical portion 664. Such deformation that separates the protruding portion 666 from the reduced diameter portion 120a of the one magnetic portion 120 can be suppressed. As a result, the state in which the flange-like protruding portion 666 engages with the reduced diameter portion 120a all around and supports the valve housing 11 in the axial direction is ensured regardless of the deformation of the second cylindrical portion 664. As described above, when the valve housing 11 is axially supported by the protruding portion 666 on the support surface 1d side, the pressing axial force N acting on the support surface 1d acting on the valve housing 11 is reliably ensured by the protruding portion 666. I can take it. Therefore, at the welding interface W between the second cylindrical portion 664 and the first magnetic portion 120, fatigue failure due to shear stress due to the pressing axial force N is suppressed, and high durability is ensured. It becomes possible.

  In addition to the above, in the magnetic circuit C formed by the first cylindrical portion 662 together with the press-fit location 120b as shown in FIG. 3, the second cylindrical portion 664 that is further away from the electromagnetic coil 61 than the cylindrical portion 662 has the weld location 120d. It is difficult to be affected by welding variations from the weld interface W to be formed. In addition, since the concave portion 665 recessed from the inner peripheral surface 662a of the first cylindrical portion 662 in the second cylindrical portion 664 is closed by the outer peripheral surface 120c of the first magnetic portion 120, the radial gap Gr is formed. It is easy to ensure the surface accuracy of the outer peripheral surface 120c, which is also the press-fitting surface to the first cylindrical portion 662. Furthermore, according to the 1st magnetic part 120 in which the welding location 120d is formed thicker than the 2nd cylindrical part 664, and rigidity is ensured, it is hard to deform | transform with welding heat. According to these, the magnetic flux density reduction of the magnetic circuit C due to the welding variation of the welding interface W and the surface roughness of the outer peripheral surface 120c, and the drive inhibition of the valve member 40 due to the deformation of the first magnetic part 120, Either can be suppressed. Therefore, this also makes it possible to stabilize the drive characteristics of the valve member 40.

(Second embodiment)
As shown in FIGS. 6 and 7, the second embodiment of the present invention is a modification of the first embodiment. In the second embodiment shown in FIG. 6, the radial gap Gr between the second cylindrical portion 664 of the coil housing 66 and the first magnetic portion 120 of the valve housing 11 is not the second cylindrical portion 664 side but the first cylindrical portion 664. It is formed by a recess 125 provided on the one magnetic part 120 side.

  Specifically, the recess 125 is recessed from the outer peripheral surface 120 c of the first magnetic unit 120 toward the inner peripheral side in the radial direction. In the present embodiment, the concave portion 125 is formed in an annular groove shape that extends over the entire region in the circumferential direction and extends over the entire region of the inner peripheral side portion 120d of the second cylindrical portion 664 in the axial direction. . On the other hand, the inner peripheral surface 664a of the second cylindrical portion 664 is formed in a cylindrical hole shape having a substantially constant diameter throughout the entire axial direction. With this configuration, in the present embodiment, a radial gap continuous in the circumferential direction between the inner peripheral surface 664a of the second cylindrical portion 664 that closes the opening 125a of the concave portion 125 of the first magnetic portion 120 and the concave portion 125. Gr is formed. And the 2nd cylindrical part 664 is welded to the 1st magnetic part 120 of the inner peripheral side in the whole area of the circumferential direction through this radial direction clearance gap Gr.

  As shown in FIG. 7, in the present embodiment, the outer peripheral surface 664 b of the second cylindrical portion 664 is formed to be recessed from the outer peripheral surface 662 b of the first cylindrical portion 662. The radial thickness T2 of 664 is set to be thinner than the minimum radial thickness T1 of the first cylindrical portion 662. Further, with respect to the radial thickness T2 of the second cylindrical portion 664, the radial thickness of the welded portion 120d of the first magnetic portion 120 is set such that the interval Δr of the radial gap Gr is less than half. The length Tvh is set to be thin.

  According to the second embodiment described above, according to the first embodiment, stable driving characteristics and high durability of the valve member 40 can be obtained, and the outer peripheral surface 120c of the first magnetic part 120 is processed. This facilitates the forming operation of the recess 125 and increases the productivity.

(Other embodiments)
Although a plurality of embodiments of the present invention have been described above, the present invention is not construed as being limited to these embodiments, and can be applied to various embodiments without departing from the scope of the present invention. .

  Specifically, in the first and second embodiments, welding of the second cylindrical portion 664 of the coil housing 66 and the first magnetic portion 120 of the valve housing 11 is, for example, arc welding or plasma welding in addition to laser welding. Etc. may be performed. Moreover, the radial clearance between the second cylindrical portion 664 of the coil housing 66 and the first magnetic portion 120 of the valve housing 11 is obtained by combining the recess 665 of the first embodiment and the recess 125 of the second embodiment. Gr may be formed. Furthermore, in the second embodiment, the outer peripheral surface 664b of the second cylindrical portion 664 and the outer peripheral surface 662b of the first cylindrical portion 662 may be formed so as to be substantially cylindrical with a constant diameter. .

DESCRIPTION OF SYMBOLS 1 Internal combustion engine, 1c Mounting hole, 1d Support surface, 2 Fuel piping, 10 Fuel injection valve, 11 Valve housing, 12 Pipe member, 13 Inlet member, 14 Nozzle member, 18 Injection hole, 20 Fixed core, 30 Movable core, 40 Valve member, 50 First elastic member, 52 Second elastic member, 60 Drive portion, 61 Electromagnetic coil, 62 Resin bobbin, 64 Connector, 66 Coil housing, 120 First magnetic portion, 120a Reduced diameter portion, 120b Press-fit location, 120c Outer peripheral surface, 120d welding location, 121 non-magnetic portion, 122 second magnetic portion, 125, 665 recess, 125a, 665a opening, 660 coil housing portion, 662 first cylindrical portion, 662a inner peripheral surface, 662b outer peripheral surface, 664 Second cylindrical portion, 664a inner peripheral surface, 664b outer peripheral surface, 666 protruding portion, 666a, 666b Axial direction End face, C magnetic circuit, Gr radial clearance, N pressing axial force, W welding interface, Δr interval

Claims (7)

A fuel injection valve for intermittently injecting fuel from an injection hole to the internal combustion engine by reciprocating movement of a valve member under a state of being pressed against a support surface of the internal combustion engine by the pressure of fuel supplied from a fuel pipe;
A cylindrical valve housing that houses the valve member, and a pressing axial force acts toward the support surface by the pressure of fuel supplied from the fuel pipe;
An electromagnetic coil that is disposed on the outer peripheral side of the valve housing and generates a magnetic force for driving the valve member by energization;
A coil housing that covers the electromagnetic coil from the outer peripheral side and is supported by the support surface;
In the fuel injection valve comprising: the coil housing,
A first cylindrical shape in which the valve housing is press-fitted on the inner peripheral side closer to the support surface than the electromagnetic coil, and forms a magnetic circuit with the valve housing for generating the magnetic force in response to energization of the electromagnetic coil. And
A second tubular portion which is adjacent to the support surface side with respect to the first tubular portion and is welded to the valve housing through a radial gap formed between the valve housing and the inner peripheral side;
A protrusion for engaging the second tubular portion Kiben front housing protrudes into the inner circumferential side than sandwiching between said first cylindrical portion,
Have
The radial thickness of the portion where the second cylindrical portion is welded through the radial gap in the valve housing is thicker than the radial thickness of the portion where the first cylindrical portion is press-fitted in the valve housing. A fuel injection valve characterized by.   2. The fuel injection according to claim 1, wherein the valve housing has a reduced diameter portion that is reduced in diameter toward the support surface, and the flange-like protruding portion is engaged with the reduced diameter portion. valve.   3. The fuel injection valve according to claim 1, wherein a radial thickness of the second cylindrical portion is thinner than a radial thickness of the first cylindrical portion.   4. The radial thickness of the second cylindrical portion is thinner than a radial thickness of a portion where the second cylindrical portion is welded in the valve housing. The fuel injection valve described in 1.   The radial gap between the second cylindrical portion and the valve housing is formed at an interval of less than half of the radial thickness of the second cylindrical portion. The fuel injection valve as described in any one of -4.   The second cylindrical portion has a concave portion that is recessed toward the outer peripheral side with respect to the inner peripheral surface of the first cylindrical portion, and between the outer peripheral surface of the valve housing that closes the opening of the concave portion and the concave portion. The fuel injection valve according to any one of claims 1 to 5, wherein a radial gap is formed.   The valve housing has a recess that is recessed from the outer peripheral surface of the valve housing to the inner peripheral side, and the radial clearance between the inner peripheral surface of the second tubular portion that closes the opening of the recess and the recess. The fuel injection valve according to claim 1, wherein the fuel injection valve is formed.

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