JP5892372B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve that injects and supplies fuel to an internal combustion engine.

  2. Description of the Related Art Conventionally, there is known an electromagnetic fuel injection valve that injects fuel, which is pressurized and pressurized from a fuel tank by a high-pressure pump, and accumulated in a delivery pipe into an internal combustion engine. During the valve opening operation, the fuel injection valve attracts the movable core to the fixed core side by electromagnetic attraction generated by energizing the coil, and the needle that moves together with the movable core separates from the valve seat to inject fuel. . Further, during the valve closing operation, when the energization to the coil is stopped and the electromagnetic attractive force is lost, the needle comes into contact with the valve seat and stops the fuel injection.

  In the fuel injection valve, the residual suction force generated by the magnetic flux remaining after the energization of the coil is stopped during the valve closing operation attracts the movable core toward the fixed core. For this reason, the state where the needle is separated from the valve seat is maintained, and fuel is injected excessively, and the amount of fuel injection injected by one valve opening increases. Patent Document 1 includes an electromagnetic valve that includes a magnetic restrictor through which a magnetic path passes, and that reduces a residual attractive force that is generated when driving a large current value in a coil (hereinafter referred to as “high pulse driving”). Have been described.

JP 2006-138325 A

  However, in the electromagnetic valve described in Patent Document 1, all the magnetic paths that generate the electromagnetic attractive force pass through the magnetic restrictor, so that the magnetic restrictor is configured for high pulse drive. In this case, a large residual attraction force is generated in the drive when a current having a small current value flows through the coil (hereinafter referred to as “low pulse drive”). For this reason, the time from when the distance between the needle and the valve seat (hereinafter referred to as “lift amount”) becomes maximum until the time when the valve closing operation starts becomes longer, and the fuel injection that is injected by one opening of the valve The amount increases.

  An object of the present invention is to provide a fuel injection valve capable of reducing the fuel injection amount when driven with a small current value.

The present invention is a fuel injection valve comprising a magnetic throttle member provided in the vicinity of a coil on the outer side in the radial direction of the housing and a magnetic path forming member provided on the opposite side of the coil of the magnetic throttle member on the outer side in the radial direction of the housing. When the coil is energized, a short magnetic path having a relatively short magnetic path length through the magnetic aperture member, and a long magnetic path having a magnetic path length longer than the short magnetic path length through the magnetic path forming member A path is formed.

In the low pulse drive, when energization to the coil is started, a short magnetic path passing through the magnetic aperture member is first formed, and an electromagnetic attractive force is generated between the fixed core and the movable core. When the current flowing through the coil increases, the magnetic diaphragm member becomes magnetically saturated and generates a constant attractive force. On the other hand, a new magnetic attractive force is generated by a long magnetic path formed at a position away from the coil, and the lift amount is maximized. To. Since the time variation of the electromagnetic attraction force due to the long magnetic path is small compared to the time variation of the electromagnetic attraction force due to the short magnetic path, the electromagnetic attraction force when the lift amount is maximized is smaller than that of the conventional fuel injection valve. Become. Further, when the current value of the current flowing through the coil decreases from the maximum value, the electromagnetic attractive force of the long magnetic path decreases faster than the electromagnetic attractive force of the short magnetic path. Decrease. Thereby, compared with the conventional fuel injection valve, the valve closing operation in which the lift amount changes from the maximum to 0 can be started earlier. In addition, in high pulse drive, when energization of the coil is started, a long magnetic path is formed following the short magnetic path, so that sufficient electromagnetic attraction force is generated to attract the movable core toward the fixed core. can do.
Therefore, a sufficient electromagnetic attractive force can be generated in the high pulse driving and the valve closing operation can be started early in the low pulse driving, so that the fuel injection amount injected by one valve opening can be reduced.

It is sectional drawing of the fuel injection valve by 1st Embodiment of this invention. It is a principal part expanded sectional view of the fuel injection valve by 1st Embodiment of this invention. It is a principal part expanded sectional view explaining the magnetic path formed in the fuel injection valve by 1st Embodiment of this invention. It is a characteristic view which shows the time change of the action | operation in the case of the low pulse drive of the fuel injection valve by 1st Embodiment of this invention. It is a characteristic view which shows the time change of the action | operation in the case of the high pulse drive of the fuel injection valve by 1st Embodiment of this invention. It is a principal part expanded sectional view of the fuel injection valve by 2nd Embodiment of this invention. It is a principal part expanded sectional view of the fuel injection valve by 3rd Embodiment of this invention. It is a principal part expanded sectional view explaining the magnetic path formed in the fuel injection valve by 3rd Embodiment of this invention.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A fuel injection valve according to a first embodiment of the present invention is shown in FIG. The fuel injection valve 1 is used, for example, in a fuel injection device of a direct injection gasoline engine (not shown), and injects and supplies gasoline as fuel to the engine.

  The fuel injection valve 1 includes a housing 20, a needle 40, a movable core 50, a fixed core 60, a coil 70, a first magnetic member 81, a second magnetic member 82, a spring 91, a spring 92, and the like.

  As shown in FIG. 1, the housing 20 includes a first cylinder member 21, a second cylinder member 22, a third cylinder member 23, and an injection nozzle 30. The first cylinder member 21, the second cylinder member 22, and the third cylinder member 23 are all formed in a substantially cylindrical shape, and are coaxial in the order of the first cylinder member 21, the second cylinder member 22, and the third cylinder member 23. Arranged and connected to each other.

  The 1st cylinder member 21 and the 3rd cylinder member 23 are formed, for example with magnetic materials, such as ferritic stainless steel, and the magnetic stabilization process is performed. The first cylinder member 21 and the third cylinder member 23 have a relatively low hardness. On the other hand, the second cylindrical member 22 is formed of a nonmagnetic material such as austenitic stainless steel, for example. The hardness of the second cylinder member 22 is higher than the hardness of the first cylinder member 21 and the third cylinder member 23.

  The injection nozzle 30 is provided at the end of the first cylinder member 21 opposite to the second cylinder member 22. The injection nozzle 30 is made of a metal such as martensitic stainless steel. The injection nozzle 30 is subjected to a quenching process so as to have a predetermined hardness.

  The injection nozzle 30 is formed in a substantially bottomed cylindrical shape and has a bottom portion 31 and a cylindrical portion 32. The bottom portion 31 closes one end portion of the cylindrical portion 32. An injection hole 311 that connects the inner wall and the outer wall is formed in the bottom 31. An annular valve seat 312 is formed on the inner wall of the bottom 31 so as to surround the nozzle hole 311. The cylinder portion 32 is connected to the first cylinder member 21 such that the outer wall is fitted to the inner wall of the first cylinder member 21. The fitting part of the cylinder part 32 and the 1st cylinder member 21 is welded.

  The needle 40 is formed in a rod shape from a metal such as martensitic stainless steel. The needle 40 is quenched to have a predetermined hardness. The hardness of the needle 40 is set substantially equal to the hardness of the injection nozzle 30.

  The needle 40 is accommodated in the housing 20 so as to be reciprocally movable in the axial direction of the housing 20. The needle 40 includes a main body 41, a seal portion 42, a large diameter portion 44, a spring contact portion 48, and the like. The main body 41 is formed in a substantially cylindrical rod shape. The seal portion 42 is formed at the end of the main body 41 on the valve seat 312 side, and can contact the valve seat 312.

  The large diameter portion 44 is formed on the opposite side of the seal portion 42 of the main body 41. The large diameter portion 44 has a larger outer diameter than the main body 41 and is formed integrally with the main body 41. An annular first step surface 45 is formed between the large diameter portion 44 and the main body 41 so as to be perpendicular to the axis of the large diameter portion 44.

  The spring contact portion 48 is formed on the opposite side to the main body 41 of the large diameter portion 44. The spring contact portion 48 has a smaller outer diameter than the large diameter portion 44 and is formed integrally with the large diameter portion 44.

  Further, a sliding contact portion 46 is formed in the vicinity of the seal portion 42 of the main body 41. The sliding contact portion 46 is formed in a substantially cylindrical shape, and a part of the outer wall 461 is chamfered. The slidable contact portion 46 can be slidably contacted with the inner wall 321 of the cylindrical portion 32 of the injection nozzle 30 at a portion where the outer wall 461 is not chamfered. As a result, the needle 40 is guided to reciprocate at the tip of the nozzle hole 311 side.

  The needle 40 opens and closes the nozzle hole 311 when the seal portion 42 is separated from the valve seat 312 or abuts against the valve seat 312. Hereinafter, as shown in FIG. 1, a direction in which the needle 40 is separated from the valve seat 312 is referred to as a valve opening direction, and a direction in which the needle 40 contacts the valve seat 312 is referred to as a valve closing direction. The end of the main body 41 of the needle 40 on the large diameter portion 44 side and the large diameter portion 44 are formed in a hollow cylindrical shape. A hole 411 that connects the inner wall and the outer wall is formed at the end of the main body 41 on the large diameter portion 44 side.

  The movable core 50 is formed in a substantially cylindrical shape by a magnetic material such as ferritic stainless steel. The movable core 50 is subjected to a magnetic stabilization process. The hardness of the movable core 50 is relatively low and is substantially equal to the hardness of the first cylindrical member 21 and the third cylindrical member 23 of the housing 20.

The movable core 50 has a large-diameter inner wall surface 51, a small-diameter inner wall surface 52, a step surface 53, and the like. The inner diameter of the large-diameter inner wall surface 51 formed on the fixed core 60 side is larger than the outer diameter of the large-diameter portion 44 of the needle 40. The small-diameter inner wall surface 52 is formed on the inner wall on the seal portion 42 side with respect to the large-diameter inner wall surface 51 among the inner walls of the movable core 50. The inner diameter of the small-diameter inner wall surface 52 is smaller than the inner diameter of the large diameter inner wall 51, and larger than the outer diameter of the body 4 1 of the needle 40. An annular step surface 53 is formed between the small-diameter inner wall surface 52 and the large-diameter inner wall surface 51 so as to be perpendicular to the axis of the small-diameter inner wall surface 52.

  The fixed core 60 is formed in a substantially cylindrical shape by a magnetic material such as ferritic stainless steel. The fixed core 60 is subjected to a magnetic stabilization process. The fixed core 60 has a relatively low hardness and is approximately equal to the hardness of the movable core 50. The fixed core 60 is provided so as to be fixed inside the housing 20. The fixed core 60 and the third cylinder member 23 of the housing 20 are welded.

  The first magnetic member 81 is formed of a magnetic material such as ferritic stainless steel, for example, and is provided on the radially outer side of the third cylindrical member 23. More specifically, the coil 70 is provided away from the coil 70 on the opposite side to the valve seat 312 side in the axial direction of the housing 20. The first magnetic member 81 is formed in a substantially annular shape, and the axial length of the housing 20 is a length d1 as shown in FIG. The first magnetic member 81 corresponds to a “magnetic diaphragm member” recited in the claims.

The second magnetic member 82 is formed of the same material as the first magnetic member 83 , for example, a magnetic material such as ferritic stainless steel, and is provided on the radially outer side of the third cylindrical member 23. More specifically, the coil 70 is provided away from the coil 70 on the side opposite to the valve seat 312 side in the axial direction of the housing 20, and further away from the coil 70 than the first magnetic member 81. ing. The second magnetic member 82 is formed in a substantially annular shape, and the axial length d2 of the housing 20 is longer than the length d1. The first magnetic member 81 and the second magnetic member 82 are provided apart from each other by a resin member that covers the radially outer side of the third cylindrical member 23. The second magnetic member 82 corresponds to a “magnetic path forming member” recited in the claims.

  The coil 70 is formed in a substantially cylindrical shape and is provided so as to surround the radially outer side of the second cylinder member 22 and the third cylinder member 23 of the housing 20. The coil 70 generates a magnetic flux when a current flows. When the coil 70 generates magnetic flux, two magnetic paths are formed in the fuel injection valve 1 as shown in FIG. The first magnetic path M <b> 1 as the “short magnetic path” passes through the fixed core 60, the third cylindrical member 23, the first magnetic member 81, the holder 17, the first cylindrical member 21, and the movable core 50 to return to the fixed core 60. Return magnetic path. The second magnetic path M2 as the “long magnetic path” is a large diameter of the fixed core 60, the third cylindrical member 23, the second magnetic member 82, the holder 17, the first cylindrical member 21, the movable core 50, and the needle 40. This is a magnetic path that returns to the fixed core 60 again through the portion 44. The magnetic path length of the second magnetic path M2 is longer than the magnetic path length of the first magnetic path M1.

  One end of the spring 91 is provided so as to contact the spring contact portion 48 of the needle 40. The other end of the spring 91 as “biasing means” abuts on one end of the adjusting pipe 11 that is press-fitted and fixed inside the fixed core 60. The spring 91 urges the needle 40 together with the movable core 50 in the valve closing direction.

  The spring 92 is provided so that one end is in contact with the stepped surface 54 of the movable core 50. The other end of the spring 92 abuts on an annular step surface 211 formed inside the first cylindrical member 21 of the housing 20. The spring 92 urges the movable core 50 together with the needle 40 in the valve opening direction.

  In the fuel injection valve 1 according to the first embodiment, the biasing force due to the elasticity of the spring 91 is set larger than the biasing force due to the elasticity of the spring 92. Therefore, the urging force that the springs 91 and 92 act on the needle 40 is a resultant force obtained by subtracting the urging force due to the elasticity of the spring 92 from the urging force due to the elasticity of the spring 91 (hereinafter referred to as “spring urging force”). When no current flows through the coil 70, the seal portion 42 of the needle 40 is brought into contact with the valve seat 312 by a spring biasing force, that is, in a closed state.

  As shown in FIG. 1, a substantially cylindrical fuel introduction pipe 12 is press-fitted and welded to the end of the third cylinder member 23 opposite to the second cylinder member 22. A filter 13 is provided inside the fuel introduction pipe 12. The filter 13 collects foreign matters in the fuel that has flowed from the introduction port 14 of the fuel introduction pipe 12.

  The radially outer sides of the fuel introduction pipe 12 and the third cylinder member 23 are molded with resin. A connector 15 is formed in the mold part. The connector 15 is insert-molded with a terminal 16 for supplying electric power to the coil 70. Further, a cylindrical holder 17 is provided outside the coil 70 in the radial direction so as to cover the coil 70.

  The fuel that has flowed from the introduction port 14 of the fuel introduction pipe 12 flows into the fixed core 60, the adjusting pipe 11, the spring contact portion 48 of the needle 40, the inside of the large diameter portion 44 and the main body 41, the hole 411, and the first cylinder member 21. Between the injection nozzle 30 and the needle 40 and led to the vicinity of the injection hole 311. That is, a fuel passage 18 through which fuel flows is formed inside the housing 20. Note that when the fuel injection valve 1 is operated, the periphery of the movable core 50 is filled with fuel.

  Next, the operation of the fuel injection valve 1 will be described with reference to FIGS. Here, description will be given by dividing into two driving states of low pulse driving and high pulse driving depending on the magnitude of the current flowing in the coil 70.

  First, the behavior of the needle 40 in the low pulse drive will be described mainly based on FIG. FIG. 4A shows a time change of the current value of the current flowing through the coil 70. FIG. 4B shows a time change of the electromagnetic attractive force acting between the movable core 50 and the fixed core 60. FIG. 4C shows a change over time in the lift amount. 4 (b) and 4 (c) show changes over time in the electromagnetic attraction force and lift amount in the fuel injection valve of the comparative example, along with solid lines L10 and L20 showing the time change in electromagnetic attraction force and lift amount of the fuel injection valve 1. The alternate long and short dash lines L11 and L21 are also shown. The fuel injection valve of the comparative example includes a magnetic member having a sufficient length in the axial direction of the housing 20 instead of the first magnetic member 81.

  When energization of the coil 70 is started at time t <b> 10, the coil 70 generates a magnetic flux, and the fuel injection valve 1 generates an electromagnetic attractive force by the first magnetic path M <b> 1 formed near the coil 70. Since the magnetic path length of the first magnetic path M1 is shorter than that of the second magnetic path M2, the magnetic path is formed quickly, and the time change of the electromagnetic attractive force is large. Note that, in the fuel injection valve of the comparative example, similarly to the fuel injection valve 1, an electromagnetic attractive force is generated. The value of the current flowing through the coil 70 increases monotonously from time t10 to time t12.

At time t11, since the first magnetic member 81 through which the first magnetic path M1 passes becomes “magnetic saturation” in which the magnetization does not change regardless of the increase in magnetic flux, the magnitude of the electromagnetic attractive force by the first magnetic path M1 is large. The height reaches a peak at the magnitude of the acting force F1. In the present embodiment, the magnitude of the acting force F1 is the fuel pressure at which the pressure of the fuel in the fuel passage 18 immediately before the fuel is injected from the injection hole 311 acts on the seat where the seal portion 42 and the valve seat 312 abut, And the magnitude of the resultant force of the spring biasing force is the same.
Since the current value of the current flowing through the coil 70 increases monotonously until time t12, the second magnetic path M2 passing through the second magnetic member 82 is formed by the magnetic saturation of the first magnetic member 81. At time t11, the movable core 50 moves to the fixed core 60 side, that is, starts the valve opening operation, and the lift amount increases from 0 as shown in FIG.

From time t11 to time t12, the magnitude of the electromagnetic attractive force by the first magnetic path M1 remains the same as the magnitude of the acting force F1, whereas the electromagnetic attractive force by the second magnetic path M2 increases. Since the magnetic path length of the second magnetic path M2 is longer than the magnetic path length of the first magnetic path M1, the time change of the electromagnetic attraction force by the second magnetic path M2 is the electromagnetic attraction by the first magnetic path M1. Not as big as the time change by force. As a result, as shown in FIG. 4B, the lift amount gradually increases between time t11 and time t12.
On the other hand, in the fuel injection valve of the comparative example, the magnetic member through which the magnetic path passes is not magnetically saturated, as indicated by the one-dot chain line L11 in FIG. The lift amount also increases.

  At time t12, the current value A1 is the maximum current value. In the fuel injection valve 1, the electromagnetic attractive force by the first magnetic path M1 and the second magnetic path M2 is the maximum attractive force Fm1, and the lift amount is also maximum. On the other hand, in the fuel injection valve of the comparative example, since the electromagnetic attraction force monotonously increases from time t10 to time t12, the attraction force Fm2 is greater than the attraction force Fm1, and the lift amount is also maximized.

  In the low pulse driving, the current value starts decreasing immediately after time t12 and becomes zero. For this reason, both the fuel injection valve 1 and the fuel injection valve of the comparative example reduce the electromagnetic attraction force, so the lift amount also decreases. Here, the acting force that must be applied to the movable core 50 in order to maintain the lift amount at a maximum is defined as an acting force F2. The magnitude of the acting force F2 is the resultant force of the fuel pressure and the spring biasing force that acts on the seat where the seal portion 42 and the valve seat 312 come into contact with the pressure of the fuel in the fuel passage 18 after the fuel is injected from the injection hole 311. Is smaller than the acting force F1.

  After time t12, the magnitude of the electromagnetic attractive force of the fuel injection valve 1 gradually decreases from the attractive force Fm1, and becomes the same as the magnitude of the acting force F2 at time t13. In the fuel injection valve 1, since the lift amount starts decreasing at time t13, that is, the valve closing operation starts, the time from when the lift amount reaches the maximum until the valve closing operation starts is the time t12 and the time 13 is a time P <b> 1.

  On the other hand, in the fuel injection valve of the comparative example, as shown in FIG. 4B, the magnitude of the electromagnetic attractive force becomes the same as the magnitude of the acting force F2 at time t14. In the fuel injection valve of the comparative example, since the valve closing operation starts at time t14, the time from when the lift amount reaches the maximum until the valve closing operation starts is the time between time t12 and time 14. P2, which is longer than time P1.

  Thereafter, the lift amount of the fuel injection valve 1 decreases as indicated by the solid line L20 shown in FIG. 4C, and the lift amount becomes zero at time t15. Further, the lift amount of the fuel injection valve of the comparative example decreases as indicated by the alternate long and short dash line L21, and the lift amount becomes 0 at time t16. The time variation of the lift amount from when the lift amount reaches the maximum to 0 is the same between the fuel injection valve 1 and the fuel injection valve of the comparative example.

  Next, the behavior of the needle 40 in the high pulse drive will be described mainly based on FIG. FIG. 5A shows a change over time of the current value of the current flowing through the coil 70. FIG. 5B shows a change over time of the electromagnetic attractive force acting between the movable core 50 and the fixed core 60. FIG. 5C shows a change over time in the lift amount. FIGS. 5B and 5C show one point indicating the time variation of the electromagnetic attraction force of the fuel injection valve of the comparative example, along with solid lines L30 and L40 indicating the time variation of the electromagnetic attraction force and the lift amount of the fuel injection valve 1. The chain lines L31 and L41 are also shown.

  When energization of the coil 70 is started at time t20, the coil 70 generates a magnetic flux, and an electromagnetic attraction force is generated in the fuel injection valve 1 by the first magnetic path M1 formed near the coil 70. . The magnetic path formation of the first magnetic path M1 is faster than the magnetic path formation of the second magnetic path M2, and the time variation of the electromagnetic attractive force is larger in the first magnetic path M1 than in the second magnetic path M2. Is the same as in the case of low pulse driving. The current value of the current flowing through the coil 70 increases monotonously from time t20 to time t22, and at time t22, a current having a current value A2 larger than the current value A1 energized by low pulse driving flows through the coil 70.

At time t21, in the fuel injection valve 1, the magnitude of the electromagnetic attraction force by the first magnetic path M1 reaches a peak at the magnitude of the acting force F1 as in the case of the low pulse driving described above, and the second magnetic field is reached after time t21. An electromagnetic attractive force is generated by the path M2. In the fuel injection valve 1, at time t21, the movable core 50 starts moving toward the fixed core 60, and the lift amount increases from 0 as shown in FIG.
On the other hand, the fuel injection valve of the comparative example increases after time t21 as well as between time t20 and time t21. In the fuel injection valve of the comparative example, the magnitude of the electromagnetic attractive force is the same as the magnitude of the acting force F1 at time t21, so that the lift amount increases from 0 as shown in FIG.

  At time t22, the current value of the current flowing through the coil 70 becomes the maximum current value A2. In the fuel injection valve 1, the magnitude of the electromagnetic attraction force by the first magnetic path M1 and the second magnetic path M2 becomes the maximum attraction force Fm3 at time t22, and the lift amount becomes the maximum. In the fuel injection valve of the comparative example, since the electromagnetic attractive force monotonously increases from time t20 to time t22, the attractive force Fm4 is larger than the attractive force Fm3, and the lift amount is also maximized.

  In the high pulse driving, the current decreases to a constant current value A3 after time t22 when the current value becomes the maximum, and the coil 70 is continuously supplied with the current having the constant current value A3. Thereby, a valve opening state is maintained. In the fuel injection valve 1, the second magnetic path M <b> 2 disappears due to a decrease in the current value, and an electromagnetic attractive force is generated only by the first magnetic path M <b> 1. At this time, the electromagnetic attractive force of the fuel injection valve 1 is an acting force F3. As shown in FIG. 5B, the acting force F3 is a suction force that is smaller than the acting force F1 and larger than the acting force F2, and is a suction force that can maintain the maximum lift amount. Similarly, the fuel injection valve of the comparative example also has the acting force F3 and maintains the maximum lift amount.

When the current value of the current flowing through the coil 70 decreases from the current value A3 at time t23, the electromagnetic attractive force of both the fuel injection valve 1 and the fuel injection valve of the comparative example decreases. When the magnitude of the electromagnetic attractive force between the movable core 50 and the fixed core 60 becomes the same as the magnitude of the acting force F2 at time t24, as indicated by the solid line L40 and the alternate long and short dash line L41 in FIG. The valve closing operation starts.
Thereafter, the lift amount of both the fuel injection valve 1 and the fuel injection valve of the comparative example similarly decreases according to the decrease of the electromagnetic attractive force, and the lift amount becomes zero when the electromagnetic attractive force becomes zero. In fuel injection with high pulse drive, the time from when the lift amount in the fuel injection valve 1 reaches the maximum (time t22) to when the valve closing operation starts (time t23) is the same as that in the fuel injection valve of the comparative example. This is the same as the time from when the lift amount reaches the maximum to when the valve closing operation starts.

  Since the first magnetic member 81 included in the fuel injection valve 1 of the first embodiment has a relatively small magnetic path area depending on the axial length d1 of the housing 20, it is likely to be magnetically saturated. When the first magnetic path M1 is magnetically saturated, a second magnetic path M2 that passes through the second magnetic member 82 that is farther from the first magnetic member 81 than the coil 70 is formed. Time is secured until the lift amount of the needle 40 separated from the valve seat 312 is maximized by the electromagnetic attraction force by the first magnetic path M <b> 1 according to the formation order of such magnetic paths. In addition, since the magnetic path length of the second magnetic path M2 is longer than the magnetic path length of the first magnetic path M1, the magnitude of the electromagnetic attraction force when the lift amount is maximized compared to the conventional fuel injection valve. Make it smaller. Thereby, the electromagnetic attraction force remaining when the current value of the current flowing through the coil 70 is reduced from the maximum value becomes small. Therefore, the time from when the lift amount becomes maximum in the low pulse drive to when the valve closing operation starts can be shortened.

  Further, in the high pulse drive, the second magnetic path M2 passing through the second magnetic member 82 in addition to the first magnetic path M1 is formed, so that the electromagnetic force sufficient to attract the movable core 50 toward the fixed core 60 is obtained. A suction force can be generated. Therefore, the fuel injection valve 1 can generate an electromagnetic attractive force necessary for high pulse driving, and shorten the time from when the lift amount becomes maximum in low pulse driving to when the valve closing operation starts. The injection amount in one fuel injection can be reduced.

(Second Embodiment)
Next, the fuel injection valve by 2nd Embodiment of this invention is demonstrated based on FIG. Unlike the first embodiment, the second embodiment differs in the magnetic properties of the materials forming the two magnetic members. Here, “magnetic property” refers to a magnetic property exhibited by a material when the material is magnetized. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted.

The fuel injection valve 2 of 2nd Embodiment has the 1st magnetic member 83 and the 2nd magnetic member 84, as shown in FIG.
The first magnetic member 83 is formed of a material having a relatively low magnetic permeability, and is provided away from the coil 70 on the opposite side to the valve seat 312 side in the axial direction of the housing 20 with respect to the coil 70. The length of the first magnetic member 83 in the axial direction of the housing 20 is a length d3 as shown in FIG. The first magnetic member 83 corresponds to a “magnetic diaphragm member” recited in the claims.

  The second magnetic member 84 is formed of a material having a higher magnetic permeability than the first magnetic member 83, and the first magnetic member 83 is on the opposite side of the coil 70 from the valve seat 312 side in the axial direction of the housing 20. It is provided apart from the coil 70. The second magnetic member 84 is formed in a substantially annular shape, and the length of the housing 20 in the axial direction is the same length d3 as that of the first magnetic member 83. The second magnetic member 84 corresponds to a “magnetic path forming member” recited in the claims.

  The first magnetic member 83 having a relatively low magnetic permeability is likely to be magnetically saturated. When the value of the current flowing through the coil 70 increases, a magnetic path passing through the second magnetic member 84 is formed after the first magnetic member 83 is magnetically saturated. Thereby, the fuel injection valve 2 of the second embodiment is similar to the fuel injection valve 1 of the first embodiment in order to reduce the magnitude of the electromagnetic attraction force when the lift amount is maximized compared to the conventional one. The electromagnetic attraction force remaining when the current value of the current flowing through the coil 70 decreases from the maximum value can be reduced. Therefore, the fuel injection valve 2 of the second embodiment has the same effect as the first embodiment.

(Third embodiment)
Next, the fuel injection valve by 3rd Embodiment of this invention is demonstrated based on FIG. Unlike the first embodiment, the third embodiment is provided with only one magnetic member through which a magnetic path passes. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted.

The fuel injection valve 3 of the third embodiment has a third magnetic member 85 as shown in FIG.
The third magnetic member 85 is formed in a substantially annular shape from a magnetic material such as ferritic stainless steel, for example, and is provided away from the coil 70 on the opposite side of the coil 70 from the valve seat 312 side in the axial direction. ing. An air gap 86 is formed in the third magnetic member 85.

  As shown in FIG. 7, the air gap 86 is formed from the end 87 of the third magnetic member 85 on the side opposite to the coil 70 side to the approximate center of the third magnetic member 85. The third magnetic member 85 corresponds to a “magnetic diaphragm member” recited in the claims.

  When current flows through the coil 70 and magnetic flux is generated, two magnetic paths are virtually formed in the fuel injection valve 3 as shown in FIG. The third magnetic path M3 as the “short magnetic path” includes the fixed core 60, the third cylindrical member 23, the end portion 88 of the third magnetic member 85 on the coil 70 side, the holder 17, the first cylindrical member 21, and the movable core 50. The magnetic path passes through the fixed core 60 again. The fourth magnetic path M4 as the “long magnetic path” includes the fixed core 60, the third cylindrical member 23, the end 87 of the third magnetic member 85, the holder 17, the first cylindrical member 21, the movable core 50, and the needle. This is a magnetic path that returns to the fixed core 60 again through the 40 large-diameter portions 44.

  In the fuel injection valve 3 of the third embodiment, when a current flows through the coil 70, the third magnetic path M3 is first formed. The third magnetic member 85 through which the third magnetic path M3 passes has a small magnetic path area because the air gap 86 is formed. When the value of the current flowing through the coil 70 increases, the end portion 88 through which the third magnetic path M3 passes is magnetically saturated. When the end portion 88 is magnetically saturated, a fourth magnetic path M4 passing through the end portion 87 is formed, and the moving time of the needle 40 separated from the valve seat 312 is secured. Thereby, the fuel injection valve 3 of 3rd Embodiment has the same effect as 1st Embodiment.

(Other embodiments)
(A) In the above-described embodiment, the magnitude of the electromagnetic attractive force generated when the magnetic saturation occurs is the same as the magnitude of the force required to move the needle away from the valve seat. However, the magnitude of the electromagnetic attractive force generated when magnetic saturation occurs is not limited to this.

  (A) In the first embodiment and the second embodiment described above, two magnetic members are provided. In the third embodiment, one magnetic member is provided. However, the number of magnetic members provided is not limited to this. Three or more may be provided. At this time, the magnetic member closest to the coil may be the “magnetic diaphragm member” described in the claims.

  (C) In the above-described embodiment, the magnetic member is provided away from the coil on the side opposite to the valve seat side in the axial direction of the housing with respect to the coil. However, the position where the magnetic member is provided is not limited to this. You may provide in the valve seat side of the axial direction of a housing with respect to a coil, and may be provided in the radial direction outer side of a coil.

  (D) In the above-described embodiment, the valve opening operation is started at the time when the first magnetic member is magnetically saturated. However, the time for starting the valve opening operation is not limited to this. The valve opening operation may be started before the first magnetic member is magnetically saturated, or the valve opening operation may be started after the first magnetic member is magnetically saturated.

  (E) In the second embodiment described above, the magnetic permeability of the material forming the first magnetic member is lower than the magnetic permeability of the material forming the second magnetic member. However, the magnetic properties of the material forming the first magnetic member are not limited to this. The magnetic characteristic of the material forming the first magnetic member may be lower than the magnetic characteristic of the material forming the second magnetic member. For example, the specific resistance of the material forming the first magnetic member may be higher than the specific resistance of the material forming the second magnetic member.

  (F) In the third embodiment described above, the air gap is formed up to substantially the center of the third magnetic member. However, the position where the air gap is formed is not limited to this. The air gap should just be formed in the edge part on the opposite side to the coil side of a 3rd magnetic member.

  As mentioned above, this invention is not limited to such embodiment, It can implement with a various form in the range which does not deviate from the summary.

1, 2, 3 ... fuel injection valve,
20 ・ ・ ・ Housing,
40 ... Needle,
50 ... movable core,
60 ・ ・ ・ Fixed core,
70: Coil,
91 ・ ・ ・ Spring (biasing means),
81, 83 ... 1st magnetic member (magnetic diaphragm member),
82, 84 ... second magnetic member (magnetic path forming member)
85 ... third magnetic member (magnetic diaphragm member),
86 ・ ・ ・ Air gap,
M1 ... 1st magnetic path (short magnetic path),
M2 ... 2nd magnetic path (long magnetic path),
M3 ... third magnetic path (short magnetic path),
M4: Fourth magnetic path (long magnetic path).

Claims (7)

Injection hole fuel formed in the axial end is ejected (311), a valve seat formed in the counter-outlet side of said injection hole (312), and the fuel passage fuel to the injection hole flows (18) A cylindrical housing (20) forming
A needle (40) provided in the housing so as to be capable of reciprocating in the axial direction of the housing, and opening or closing the nozzle hole by being separated from or in contact with the valve seat;
A movable core (50) provided on the valve seat side of the needle and capable of reciprocating in the axial direction of the housing together with the needle;
A fixed core (60) provided in the housing and fixed to the side opposite to the valve seat side of the movable core;
A coil (70) that generates an electromagnetic attractive force between the movable core and the fixed core by energization, and attracts the movable core in a valve opening direction;
Biasing means (91) for biasing the needle in the valve closing direction;
A magnetic throttle member (81, 83 ) provided in the vicinity of the coil on the radially outer side of the housing;
Magnetic path forming members (82, 84) provided on the outer side in the radial direction of the housing on the opposite side of the coil of the magnetic diaphragm member;
With
When the coil is energized, a short magnetic path (M1 ) having a relatively short magnetic path length through the magnetic throttle member and a magnetic path length of the short magnetic path through the magnetic path forming member A fuel injection valve characterized in that a long magnetic path (M2 ) longer than the magnetic path length is formed.   The fuel injection valve according to claim 1, wherein the magnetic throttle member is provided in an axial direction of the housing with respect to the coil.   3. The fuel injection valve according to claim 1, wherein the needle is separated from the valve seat when the magnetic throttle member is magnetically saturated by energization of the coil. The fuel injection valve according to any one of claims 1 to 3, wherein the magnetic throttle member has a magnetic path area smaller than a magnetic path area of the magnetic path forming member. The fuel injection valve according to any one of claims 1 to 4 , wherein a magnetic characteristic of a material forming the magnetic throttle member is lower than a magnetic characteristic of a material forming the magnetic path forming member. The fuel injection valve according to any one of claims 1 to 4 , wherein a magnetic permeability of a material forming the magnetic throttle member is smaller than a magnetic permeability of a material forming the magnetic path forming member. The fuel injection valve according to any one of claims 1 to 4 , wherein a specific resistance of a material forming the magnetic throttle member is higher than a specific resistance of a material forming the magnetic path forming member.

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