JP3988192B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve that injects fuel into an internal combustion engine (hereinafter referred to as an engine).

  2. Description of the Related Art Conventionally, a fuel injection valve is known in which an electromagnetic driving force for driving a valve body that opens and closes an injection hole is generated by a plurality of coils (see, for example, Patent Document 1). In general, the fuel injection valve is required to adjust the fuel injection amount to be small when the engine is started, and the same applies to the fuel injection valve using a plurality of coils.

JP-A-11-148439

However, in the conventional fuel injection valve using a plurality of coils, since energization to each coil is simultaneously performed when opening the nozzle hole, generation and disappearance of both the drive current and magnetic flux of those coils are excessively delayed. In addition, the drive circuit response of the valve body is reduced due to magnetic interference between the magnetic circuits formed by the coils and the corresponding cores. Since the drive response of the valve body is lowered, the adjustment accuracy of the fuel injection amount is also lowered, so that the above-mentioned requirement cannot be met.
An object of the present invention is to provide a fuel injection valve capable of precisely adjusting the fuel injection amount.

  According to the first to third aspects of the present invention, the driving means for opening the nozzle hole by driving the valve element closing the nozzle hole against the force of the fuel pressure in the fuel passage is an electromagnetic drive for driving the valve element. It has a plurality of coils that individually form a magnetic circuit for generating force, and the number of coils to be energized increases as the fuel pressure in the fuel passage increases. Therefore, when the fuel pressure in the fuel passage becomes low, such as when the engine is started, the generation and disappearance of both the coil drive current and the magnetic flux can be accelerated by reducing the number of energized coils. Interference can be prevented. Thereby, since the drive responsiveness of the valve body is improved, the fuel injection amount can be adjusted precisely. Moreover, when the fuel pressure in the fuel passage becomes high, the electromagnetic driving force can be reliably increased by increasing the number of coils to be energized. In this way, the number of coils to be energized can be reduced at low fuel pressures where only a small electromagnetic driving force is required, and the number of coils to be energized can be increased at high fuel pressures where a large electromagnetic driving force is required. To do.

According to the invention described in claim 2, since the plurality of magnetic circuits are formed apart from each other in the driving direction of the valve body, mutual interference of the magnetic circuits when the number of energized coils increases can be reduced. .
According to the third aspect of the present invention, the action portions that the valve body has at a plurality of locations in the driving direction are displaced by the electromagnetic driving force generated by energizing the corresponding coils. According to the present invention, the operation efficiency of the electromagnetic driving force generated when the number of energized coils is increased is higher than when all the generated electromagnetic driving force is applied to one operating portion of the valve body. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A fuel injection valve according to an embodiment of the present invention is shown in FIG. The fuel injection valve 10 is for a direct injection gasoline engine and is mounted on an engine head (not shown). The fuel injection valve 10 includes a housing 20, a nozzle holder 40, a nozzle body 42, coils 50, 52 and 54, drive circuits 60, 62 and 64, an electronic control unit (ECU) 66, a fuel pressure sensor 68, and stators 100, 102 and 104. , Fixed cores 70, 72, 74, needle 80, movable cores 90, 92, 94, spring 96, and the like.

  The housing 20 has a cylindrical shape, and in order from the one end side in the axial direction toward the other end side, the first magnetic part 21, the first nonmagnetic part 22, the second magnetic part 23, the second nonmagnetic part 24, the first It has a three magnetic part 25, a third nonmagnetic part 26 and a fourth magnetic part 27. Each magnetic part 21,23,25,27 is formed with a magnetic material, and each nonmagnetic part 22,24,26 is formed with a nonmagnetic material. The first nonmagnetic portion 22 prevents a magnetic short circuit between the first magnetic portion 21 and the second magnetic portion 23. The second nonmagnetic part 24 prevents a magnetic short circuit between the second magnetic part 23 and the third magnetic part 25. The third nonmagnetic portion 26 prevents a magnetic short circuit between the third magnetic portion 25 and the fourth magnetic portion 27. Although not shown in the drawing, the nonmagnetic portion is used as an appropriate position of the second magnetic portion 23 or the third magnetic portion 25 sandwiched between two magnetic circuits described later, thereby further reducing mutual interference between the magnetic circuits. Can be small.

  A cylindrical inlet member 30 is attached to one end of the housing 20 in the axial direction. Fuel is supplied to a fuel inlet 31 formed by the inlet member 30 from a fuel pump (not shown). The fuel supplied to the fuel inlet 31 passes through the fuel filter 32 installed in the fuel inlet 31 and flows into the inner peripheral side of the housing 20. The fuel filter 32 removes foreign matters contained in the passing fuel. A cylindrical nozzle body 42 is attached to the other end of the housing 20 in the axial direction via a cylindrical nozzle holder 40. The nozzle body 42 has a valve seat 44 on a conical inner wall surface having a smaller diameter toward the opposite housing side, that is, toward the downstream side of the fuel flow. Further, the nozzle body 42 has a nozzle hole 46 penetrating between a portion on the downstream side of the valve seat 44 on the conical inner wall surface and the outer wall surface.

  The three coils 50, 52, 54 are mounted on the outer peripheral side of the housing 20 via spools 51, 53, 55, respectively. The three coils 50, 52 and 54 are arranged coaxially along the axial direction of the housing 20 and are separated from each other. The first coil 50 closest to the nozzle hole 46 is connected to the first drive circuit 60 via the first terminal 61. The second coil 52 on the side opposite to the injection hole of the first coil 50 is connected to the second drive circuit 62 through the second terminal 63. The third coil 54 on the side opposite to the first coil of the second coil 52 is connected to the third drive circuit 64 via the third terminal 65. The three drive circuits 60, 62, and 64 are connected to a common ECU 66, and energize the corresponding coils 50, 52, and 54 in accordance with control signals received from the ECU 66, respectively. A fuel pressure sensor 68 as detection means is connected to the ECU 66, detects the pressure of fuel supplied from the fuel pump to the fuel inlet 31, and transmits a detection signal of the fuel pressure to the ECU 66.

  The three stators 100, 102, and 104 are each formed of a magnetic material and cover the outer peripheral sides of the corresponding coils 50, 52, and 54 so as to be separated from each other in the axial direction of the housing 20. The first stator 100 is magnetically connected to the first magnetic part 21 and the second magnetic part 23. The second stator 102 is magnetically connected to the second magnetic part 23 and the third magnetic part 25. The third stator 104 is magnetically connected to the third magnetic part 25 and the fourth magnetic part 27.

  The three fixed cores 70, 72, and 74 are each formed in a cylindrical shape from a magnetic material, and are attached to the inner peripheral side of the housing 20. The three fixed cores 70, 72, 74 are arranged coaxially along the axial direction of the housing 20 and are separated from each other. The first fixed core 70 closest to the nozzle hole 46 is fixed to the inner peripheral side of the first coil 50 with the housing 20 in between. The second fixed core 72 on the side opposite to the injection hole of the first fixed core 70 is fixed to the inner peripheral side of the second coil 52 with the housing 20 interposed therebetween. The third fixed core 74 on the anti-first fixed core side of the second fixed core 72 is fixed to the inner peripheral side of the third coil 54 with the housing 20 in between.

  The needle 80 is coaxially disposed on the inner peripheral side of the housing 20, the nozzle holder 40, and the nozzle body 42, and can reciprocate in the axial direction. The needle 80 has an abutting portion 82 that can be seated on the valve seat 44 at an end near the nozzle hole 46. A fuel passage 84 is formed between the nozzle holder 40 and the nozzle body 42 and the needle 80 to allow fuel to flow toward the nozzle hole 46 side. That is, the needle 80 is accommodated in the fuel passage 84.

  The three movable cores 90, 92, and 94 are each formed in a cylindrical shape from a magnetic material, and are attached to the outer peripheral side of the needle 80 so as to be integrally movable. The three movable cores 90, 92, 94 are arranged coaxially along the axial direction of the needle 80, that is, the driving direction, and are separated from each other. The first movable core 90 closest to the contact portion 82 faces the first fixed core 70 on the nozzle hole 46 side from the first fixed core 70. The second movable core 92 on the side of the first movable core 90 opposite to the abutting portion faces the second fixed core 72 between the fixed cores 70 and 72 on the side of the injection hole 46 from the second fixed core 72. The third movable core 94 on the anti-first movable core side of the second movable core 92 faces the third fixed core 74 between the fixed cores 72, 74 on the injection hole 46 side from the third fixed core 74.

When the first coil 50 is energized, the first coil 50, the first stator 100, the first magnetic part 21, the first movable core 90, the first fixed core 70, and the second magnetic part 23 form a magnetic circuit. A magnetic attractive force that attracts the first movable core 90 toward the first fixed core 70 is generated. That is, a magnetic attractive force as an electromagnetic driving force generated by energizing the first coil 50 acts on the first movable core 90. When the second coil 52 is energized, a magnetic circuit is formed by the second coil 52, the second stator 102, the second magnetic part 23, the second movable core 92, the second fixed core 72, and the third magnetic part 25. A magnetic attractive force that attracts the second movable core 92 toward the second fixed core 72 is generated. That is, a magnetic attractive force as an electromagnetic driving force generated by energizing the second coil 52 acts on the second movable core 92. When the third coil 54 is energized, a magnetic circuit is formed by the third coil 54, the third stator 104, the third magnetic part 25, the third movable core 94, the third fixed core 74, and the fourth magnetic part 27. A magnetic attraction force that attracts the third movable core 94 toward the third fixed core 74 is generated. That is, a magnetic attractive force as an electromagnetic driving force generated by energizing the third coil 54 acts on the third movable core 94.
As described above, the coils 50, 52, 54, the drive circuits 60, 62, 64, the ECU 66 and the fixed cores 70, 72, 74 constitute drive means, and the needle 80 and the movable cores 90, 92, 94 constitute valve bodies. Each movable core 90, 92, 94 constitutes an action part.

  Each movable core 90, 92, 94 has fuel holes 91, 93, 95 penetrating between its inner wall surface and outer wall surface. The fuel flowing into the fuel inlet 31 flows into the inner peripheral side of the third movable core 94 via the fuel filter 32, the inner peripheral side of the adjusting pipe 97 described later and the inner peripheral side of the third fixed core 74. . The fuel flowing into the third movable core 94 passes through the fuel hole 95, between the third magnetic part 25 and the needle 80, and through the inner peripheral side of the second fixed core 72 to the inner peripheral side of the second movable core 92. Flow into. The fuel flowing into the second movable core 92 passes through the fuel hole 93, the second magnetic part 23 and the needle 80, and the inner peripheral side of the first fixed core 70 to the inner peripheral side of the first movable core 90. Flow into. The fuel flowing into the first movable core 90 flows into the fuel passage 84 via the fuel hole 91 and between the first magnetic part 21 and the needle 80. The pressure of the fuel flowing into the fuel passage 84 is substantially equal to the fuel pressure detected by the fuel pressure sensor 68.

  One end of the spring 96 as the urging means is locked to the end of the third movable core 94 on the side opposite to the second fixed core. The other end of the spring 96 is engaged with an adjusting pipe 97 that is press-fitted into the inner peripheral side of the third fixed core 74. The spring 96 biases the needle 80 toward the nozzle hole 46 (the lower side in FIG. 1) by applying a restoring force generated by elastic deformation to the third movable core 94.

  When energization of all the coils 50, 52, 54 is stopped, the needle 80 is biased toward the injection hole 46 by the restoring force of the spring 96, and the contact portion 82 is seated on the valve seat 44. Thereby, the communication between the fuel passage 84 and the injection hole 46 is blocked, and the fuel injection from the injection hole 46 is stopped. That is, the nozzle hole 46 is closed so that fuel cannot be injected. At this time, between the first fixed core 70 and the first movable core 90, between the second fixed core 72 and the second movable core 92, and between the third fixed core 74 and the third movable core 94. Are each formed with a gap of a predetermined size.

  When at least one coil 50, 52, 54 is energized, a magnetic attractive force acts on the movable cores 90, 92, 94 facing the fixed cores 70, 72, 74 on the inner peripheral side of the energized coils 50, 52, 54. To do. As a result, the movable cores 90, 92, and 94 on which the magnetic attractive force has acted are attracted and displaced toward the fixed cores 70, 72, and 74, that is, the counter-injection holes that face the movable cores. It is driven to the side opposite to the injection hole (upper side in FIG. 1) against the force of the fuel pressure and the biasing force of the spring 96. As a result, the abutting portion 82 is separated from the valve seat 44, so that the fuel passage 84 and the injection hole 46 communicate with each other, and the fuel in the fuel passage 84 is injected from the injection hole 46 to the outside. That is, the injection hole 46 is opened and fuel injection from the injection hole 46 is performed. Thereafter, when the energization of at least one of the coils 50, 52, 54 is stopped, the generation of the magnetic attractive force by the coils 50, 52, 54 energized until then stops, so that the needle 80 is moved by the urging force of the spring 96. It moves to the nozzle hole 46 side, and the contact part 82 is seated on the valve seat 44 again. Thus, one fuel injection operation is completed.

Here, an example of the fuel injection operation of the fuel injection valve 10 will be described in more detail.
In the fuel injection valve 10, one fuel injection is performed according to the flowchart of FIG. Specifically, first, in step S1, the fuel pressure detected by fuel pressure sensor 68 (hereinafter, detects fuel pressure that) P _d is whether lower than a predetermined first threshold value P _th1, determines the ECU 66. Here, the first threshold value P _th1 is set to a pressure lower than the maximum pressure (hereinafter referred to as the maximum fuel pressure) P _{max of} the fuel supplied to the fuel injection valve 10 and guided to the fuel passage 84. For example, when the magnetic attractive forces generated by energizing the coils 50, 52, and 54 are substantially the same, the first threshold value P _th1 is set to a pressure that is 1/3 or less of the maximum fuel pressure P _max , for example. The

In step S1, the detection pressure P _{when d} is determined to be lower than the first threshold value P _th1, the process proceeds to step S2, one of the coils of the coil 50, 52, for example, a first coil 50 Is energized, and then the energization is stopped. In step S2, the first threshold value P _th1 needs to be set in advance so that any one of the movable cores 90, 92, and 94 corresponding to the energized coil is reliably displaced. .
On the other hand, in step S1, when the detection fuel pressure P _d is determined to be the first threshold value P _th1 or more, the process proceeds to step S3.

In step S3, the detection fuel pressure P _d is whether lower than a predetermined second threshold value P _th2, determines the ECU 66. Here, the second threshold value P _th2 is set to a pressure higher than the first threshold value P _th1 and lower than the maximum fuel pressure P _max . For example, when the magnetic attractive force generated by energizing each of the coils 50, 52, and 54 is substantially the same, for example, the pressure is higher than the first threshold P _{th1 and not} more than 2/3 of the maximum fuel pressure P _max. A second threshold value P _th2 is set.

In step S3, if the detected fuel pressure P _d is determined to be lower than the second threshold value P _th2, the processing proceeds to step S4, including current target coil in the step S2 among the coils 50, 52, 54 Any two coils, for example, the first coil 50 and the second coil 52 are energized, and then the energization is stopped. In this step S4, it is necessary to set the second threshold value P _{th2 in} advance so that any two movable cores corresponding to the energized coil among the movable cores 90, 92, 94 are surely displaced. .

On the other hand, in step S3, if the detected fuel pressure P _d is determined to be the second threshold value P _th2 or more, the process proceeds to step S5, it energized all are three coils 50, 52, 54, then, The energization is stopped.
As described above, when the energization of the predetermined coils 50, 52, 54 is stopped in steps S2, S4, S5, one fuel injection is completed.

In this way the fuel injection valve 10, so as to increase the number of those that energization of the three coils 50, 52, 54 in a single fuel injection (hereinafter, referred to as the number of energizing coils), and the more detection fuel pressure P _d is increased I have to. Therefore, when the fuel pressure in the fuel passage 84 becomes low, such as when the engine is started, the number of energized coils is reduced, so that the generation and disappearance of both the coil drive current and the magnetic flux can be prevented from being excessively delayed and formed. Mutual interference of each magnetic circuit can be prevented. As a result, the drive responsiveness of the needle 80 is improved, and the fuel injection amount can be precisely adjusted. In addition, when the engine is continuously operated and the fuel pressure in the fuel passage 84 increases, the number of energizing coils is increased, thereby reliably increasing the magnetic attractive force for displacing the movable cores 90, 92, and 94 together with the needle 80. it can. As described above, the number of energizing coils is reduced and a large force is required to drive the valve body at a low fuel pressure that requires a small force to drive the valve body composed of the needle 80 and the movable cores 90, 92, and 94. Since the number of energizing coils is increased at high fuel pressure, energy efficiency is increased.

  Further, in the fuel injection valve 10, the three magnetic circuits are formed separately from each other in the axial direction of the housing 20, that is, in the driving direction of the needle 80 by the three coils 50, 52, 54, etc. The mutual interference of each magnetic circuit can be suppressed when the is increased. In addition, in the fuel injection valve 10, magnetic attraction generated by energization of the coils 50, 52, 54 that are different from each other with respect to the movable cores 90, 92, 94 mounted at three locations in the driving direction of the needle 80. Since the force is applied, the working efficiency is improved.

  In the above-described embodiment, the fuel pressure directly detected by the fuel pressure sensor is used to determine the number of energized coils. For example, the fuel pressure estimated based on the coolant temperature, the engine speed, the engine load, or the vehicle speed is used. The number of energizing coils may be determined using this. This is because, at the time of engine start when the fuel pressure is low, the coolant temperature and the engine speed are low, the engine load is small, and the vehicle speed is low, so the fuel pressure can be estimated based on these physical quantities. Because it becomes.

  In the above-described embodiment, an example in which the present invention is applied to a fuel injection valve having three coils has been described. However, the present invention is applied to a fuel injection valve having two coils or four or more coils. May be. Furthermore, in the above-described embodiment, the plurality of coils are arranged along the needle driving direction so as not to overlap in the radial direction, but the plurality of coils may be arranged to overlap in the radial direction.

Furthermore, in the above-described embodiment, the magnetic attraction force as the electromagnetic driving force generated by the plurality of coils arranged in the needle driving direction corresponds to the corresponding one of the plurality of movable cores arranged as the action portion in the needle driving direction. It is acting. On the other hand, you may make the electromagnetic drive force which generate | occur | produced with the some coil act on the same action part of a valve body.
Furthermore, in the above-described embodiment, the number of coils to be energized during one fuel injection operation is not changed. On the other hand, for example, when the fuel pressure changes during one fuel injection operation, the number of energized coils may be increased or decreased according to the change in the fuel pressure.

In addition, in the above-described embodiment, an example in which the present invention is applied to a fuel injection valve for a direct injection gasoline engine has been described. However, the present invention is applied to a fuel injection valve for a premixed gasoline engine or a diesel engine. May be.
In addition, in the above-described embodiment, the valve body that closes the nozzle hole is driven against the force caused by the fuel pressure in the fuel passage to open the nozzle hole so-called inwardly-open fuel injection valve. The invention was applied. On the other hand, in a so-called open-type fuel injection valve that has a plurality of coils and closes the nozzle hole by driving a valve element that opens the nozzle hole against the force of the fuel pressure in the fuel passage. The technical idea of increasing the number of energizing coils as the fuel pressure in the fuel passage increases may be adopted.

It is sectional drawing which shows the fuel injection valve by one Embodiment of this invention. It is a flowchart for demonstrating the fuel-injection action | operation of the fuel injection valve by one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel injection valve, 46 Injection hole, 50, 52, 54 Coil (drive means), 60, 62, 64 Drive circuit (drive means), 66 ECU (drive means), 68 Fuel pressure sensor, 70, 72, 74 Fixed core (Drive means), 80 needle (valve element), 84 fuel passage, 90, 92, 94 movable core (action part, valve element), 100, 102, 104 stator

Claims (3)

The nozzle hole,
A fuel passage for flowing fuel toward the nozzle hole,
A valve body housed in the fuel passage and opening and closing the nozzle hole;
Drive means for opening the nozzle hole by driving the valve element closing the nozzle hole against the force of fuel pressure of the fuel passage;
With
The driving means has a plurality of coils that individually form a magnetic circuit for generating an electromagnetic driving force that drives the valve body, and increases the number of coils that are energized as the fuel pressure in the fuel passage increases. A fuel injection valve characterized by:   The fuel injection valve according to claim 1, wherein the plurality of magnetic circuits are formed apart from each other in a driving direction of the valve body.   The valve body has action portions at a plurality of locations in a driving direction, and each action portion is displaced by an electromagnetic driving force generated by energizing the corresponding coil. 2. The fuel injection valve according to 2.

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